Veeco AFM DiInnova USER MANUAL-B (004-1005-000).pdf

Document Revision History

Revision Date Section(s) Affected Ref. DCR Approval

02A 5/2007 Pre-Release Draft N/A D.Kasai

A 1/2008 Initial Release N/A D.Kasai

B 11/3/08 New Updates N/A D. Paszkeicz

Copyright © [2008] Veeco Instruments Inc.All rights reserved.

User ManualFor SPM and Software

004-1005-000 (Standard)004-1005-100 (Cleanroom)

Notices: The information in this document is subject to change without notice. NO WARRANTY OF ANY KIND IS MADE WITH REGARD TO THIS MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. No liability is assumed for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of this material. This document contains proprietary information which is protected by copyright. No part of this document may be photocopied, reproduced, or translated into another language without prior written consent.Copyright: Copyright © 2004 Veeco Instruments Inc. All rights reserved. Trademark Acknowledgments: The following are registered trademarks of Veeco Instruments Inc. All other trademarks are the property of their respective owners.

Product Names:NanoScope®

MultiMode®

Dimension®

BioScope®

BioScope® IICP® IIAtomic Force Profiler® (AFP®)Dektak®

Innova®

Caliber®

Software Modes:TappingMode®

Tapping®

TappingMode+®

LiftMode®

AutoTune®

TurboScan®

Fast HSG®

PhaseImaging®

DekMap 2®

HyperScan®

StepFinder®

SoftScan®

Hardware Designs:TrakScan®

StiffStage®

Hardware Options:TipX®

Signal Access Module® and SAM®

Extender®

TipView®

Interleave®

LookAhead®

Quadrex®

Software Options:NanoScript®

Navigator®

FeatureFind®

Miscellaneous:NanoProbe®

WARRANTY INFORMATION

This product is covered by the terms of the Veeco standard warranty as in effect on the date of shipment and as reflected on Veeco's Order Acknowledgement and Quote. While a summary of the warranty statement is provided below, please refer to the Order Acknowledgement or Quote for a complete statement of the applicable warranty provisions. In addition, a copy of these warranty terms may be obtained by contacting Veeco.

WARRANTY. Seller warrants to the original Buyer that new equipment will be free of defects in material and workmanship for a period of one year commencing (x) on final acceptance or (y) 90 days from shipping, whichever occurs first. This warranty covers the cost of parts and labor (including, where applicable, field service labor and travel required to restore the equipment to normal operation). Seller warrants to the original Buyer that replacement parts will be new or of equal functional quality and warranted for the remaining portion of the original warranty or 90 days, whichever is longer.Seller warrants to the original Buyer that software will perform in substantial compliance with the written materials accompanying the software. Seller does not warrant uninterrupted or error-free operation.Seller’s obligation under these warranties is limited to repairing or replacing at Seller’s option defective non-expendable parts or software. These services will be performed, at Seller’s option, at either Seller’s facility or Buyer’s business location. For repairs performed at Seller’s facility, Buyer must contact Seller in advance for authorization to return equipment and must follow Seller’s shipping instructions. Freight charges and shipments to Seller are Buyer’s responsibility. Seller will return the equipment to Buyer at Seller’s expense. All parts used in making warranty repairs will be new or of equal functional quality. The warranty obligation of Seller shall not extend to defects that do not impair service or to provide warranty service beyond normal business hours, Monday through Friday (excluding Seller holidays). No claim will be allowed for any defect unless Seller shall have received notice of the defect within thirty days following its discovery by Buyer. Also, no claim will be allowed for equipment damaged in shipment sold under standard terms of F.O.B. factory. Within thirty days of Buyer’s receipt of equipment, Seller must receive notice of any defect which Buyer could have discovered by prompt inspection. Products shall be considered accepted 30 days following (a) installation, if Seller performs installation, or (b) shipment; unless written notice of rejection is provided to Seller within such 30-day period.Expendable items, including, but not limited to, lamps, pilot lights, filaments, fuses, mechanical pump belts, V-belts, wafer transport belts, pump fluids, O-rings and seals ARE SPECIFICALLY EXCLUDED FROM THE FOREGOING WARRANTIES AND ARE NOT WARRANTED. All used equipment is sold ‘AS IS, WHERE IS,’ WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED. Seller assumes no liability under the above warranties for equipment or system failures resulting from (1) abuse, misuse, modification or mishandling; (2) damage due to forces external to the machine including, but not limited to, acts of God, flooding, power surges, power failures, defective electrical work, transportation, foreign equipment/attachments or Buyer-supplied replacement parts or utilities or services such as gas; (3) improper operation or maintenance or (4) failure to perform preventive maintenance in accordance with Seller’s recommendations (including keeping an accurate log of preventive maintenance). In addition, this warranty does not apply if any equipment or part has been modified without the written permission of Seller or if any Seller serial number has been removed or defaced. No one is authorized to extend or alter these warranties on Seller’s behalf without the written authorization of Seller.

THE ABOVE WARRANTIES ARE EXPRESSLY IN LIEU OF ANY OTHER EXPRESS OR IMPLIED WARRANTIES (INCLUDING THE WARRANTY OF MERCHANTABILITY), AND OF ANY OTHER OBLIGATION ON THE PART OF SELLER. SELLER DOES NOT WARRANT THAT ANY EQUIPMENT OR SYSTEM CAN BE USED FOR ANY PARTICULAR PURPOSE OR WITH ANY PARTICULAR PROCESS OTHER THAN THAT COVERED BY THE APPLICABLE PUBLISHED SPECIFICATIONS.

NO CONSEQUENTIAL DAMAGES. LIMITATION OF LIABILITY. Seller shall not be liable for consequential damages, for anticipated or lost profits, incidental, indirect, special or punitive damages, loss of time, loss of use, or other losses, even if advised of the possibility of such damages, incurred by Buyer or any third party in connection with the equipment or services provided by Seller. In no event will Seller’s THE ABOVE WARRANTIES ARE EXPRESSLY IN LIEU OF ANY OTHER EXPRESS OR IMPLIED WARRANTIES (INCLUDING THE WARRANTY OF MERCHANTABILITY), AND OF ANY OTHER OBLIGATION ON THE PART OF SELLER. SELLER DOES NOT WARRANT THAT ANY EQUIPMENT OR SYSTEM CAN BE USED FOR ANY PARTICULAR PURPOSE OR WITH ANY PARTICULAR PROCESS OTHER THAN THAT COVERED BY THE APPLICABLE PUBLISHED SPECIFICATIONS.

NO CONSEQUENTIAL DAMAGES. LIMITATION OF LIABILITY. Seller shall not be liable for consequential damages, for anticipated or lost profits, incidental, indirect, special or punitive damages, loss of time, loss of use, or other losses, even if advised of the possibility of such damages, incurred by Buyer or any third party in connection with the equipment or services provided by Seller. In no event will Seller’s liability in connection with the equipment or services provided by Seller exceed the amounts paid to Seller by Buyer hereunder.

Service

Field service is available nationwide. Service and installations are performed by factory trained Veeco service personnel. Contact the Veeco Metrology sales/service office for prompt service.

Veeco Instruments Inc.112 Robin Hill Road Santa Barbara CA 93117 Attn.: Service Center

Phone: (805) 967-2700 Fax: (805) 967-7717

www.veeco.com

Disclaimer:Some images contained in this document may differ from installed equipment. The differences are usually cosmetic only and still provide useful references for the accompanying text.

Table of ContentsCh. 1 - Introduction 1

1.1 Overview of Manual ................................................................................................ 1

1.2 Safety ....................................................................................................................... 1

1.3 Microscope Specifications ....................................................................................... 21.3.1 Special Hardware Requirements.....................................................................21.3.2 Scanner Types.................................................................................................21.3.3 Scanning Techniques ......................................................................................2

1.4 SPM Fundamentals .................................................................................................. 41.4.1 Terminology....................................................................................................41.4.2 SPM Overview................................................................................................51.4.3 The Feedback Loop ........................................................................................61.4.4 Scan Size, Scan Rate, Feedback Parameters (gains) and Setpoint .................71.4.5 Main menu items ..........................................................................................111.4.6 Z Position Bar: Monitoring the Scanner's Position......................................141.4.7 Feedback Signal: Monitoring the Feedback Signal and Setpoint Values ....151.4.8 Setpoint: Setting the Reference Signal for the Feedback Loop ...................151.4.9 Setting the Gain of the Feedback Loop ........................................................161.4.10 Feedback Checkbox: Setting the Scanner's Z Position..............................17

Ch. 2 - Advanced Imaging 19

2.1 Advanced Imaging ................................................................................................. 19

2.2 Advanced Methods: ............................................................................................... 202.2.1 Scanning Thermal Microscopy (SThM) .......................................................202.2.2 Conductive AFM (C-AFM) ..........................................................................212.2.3 Liquid Imaging: ............................................................................................222.2.4 Electrostatic Force Microscopy (EFM) ........................................................232.2.5 Magnetic Force Microscopy (MFM) ............................................................242.2.6 Force Modulation Microscopy (FMM).........................................................252.2.7 Low Current STM.........................................................................................252.2.8 Scanning Capacitance Microscopy (SCM)..................................................262.2.9 Piezo Response Microscopy .........................................................................262.2.10 Electrochemistry .........................................................................................272.2.11 Surface Potential Microscopy (Kelvin Probe Microscopy) ........................27

2.3 Accessories and documents ................................................................................... 282.3.1 Heater Cell ....................................................................................................28

Table of ContentsCh. 3 - Safety 29

3.1 Operating Safety .................................................................................................... 293.1.1 Safety Symbols .............................................................................................293.1.2 Definitions: Warning, Caution, and Note .....................................................303.1.3 Summary of Warnings and Cautions ............................................................313.1.4 Grounding Innova .........................................................................................323.1.5 Setting the Line Voltage ...............................................................................32

3.2 Laser Safety ........................................................................................................... 33

3.3 Specifications and Performance............................................................................. 35

3.4 Innova User Documentation .................................................................................. 373.4.1 Innova User’s Guide ....................................................................................373.4.2 SPMLab Display and Image Analysis ..........................................................37

Ch. 4 - Installation and Set-Up 39

4.1 Overview:............................................................................................................... 39

4.2 Facilities................................................................................................................. 394.2.1 Acoustic/Vibration Specifications ................................................................404.2.2 Space requirements .......................................................................................40

4.3 Cable Connections ................................................................................................. 42

4.4 Removing and Installing the Scanner .................................................................... 44

4.5 Starting Innova....................................................................................................... 46

4.6 Loading a Sample .................................................................................................. 47

4.7 Installing a Chip Carrier ........................................................................................ 49

4.8 Loading a Probe Cartridge ..................................................................................... 53

4.9 Using the WinTV32............................................................................................... 534.9.1 Using the Innova Optics ...............................................................................53

4.10 Aligning the Deflection Sensor............................................................................ 574.10.1 Aligning the Laser Spot ..............................................................................57

Table of Contents4.10.2 Aligning the Deflection Sensor...................................................................58

4.11 Troubleshooting Tips ........................................................................................... 59

4.12 Typical startup ..................................................................................................... 59

4.13 Deflection Sensor................................................................................................. 624.13.1 Alignment Knobs ........................................................................................624.13.2 Laser Indicators...........................................................................................64

4.14 Motor stage controls ............................................................................................ 66

4.15 Engage ................................................................................................................. 67

Ch. 5 - Realtime Controls 69

5.1 The Scanning Control Dialog Window: ................................................................ 69

5.2 Area Scanning........................................................................................................ 69

5.3 Line Scanning ........................................................................................................ 71

5.4 Scanning Window Tools........................................................................................ 73

5.5 Probe Positioning................................................................................................... 78

5.6 LiftMode Settings .................................................................................................. 79

5.7 Scanning Conditions Window ............................................................................... 81

5.8 Point Spectroscopy Window.................................................................................. 81

5.9 IV Curves ............................................................................................................... 82

5.10 Signal Tracing Window ....................................................................................... 83

5.11 Probe Position Window ....................................................................................... 83

Ch. 6 - Menus 85

6.1 File Menu............................................................................................................... 85

Table of Contents6.2 Setup Menu ............................................................................................................ 86

6.3 Real Time Control Menu ....................................................................................... 87

6.4 Tools Menu ............................................................................................................ 88

6.5 Window Menu ....................................................................................................... 896.5.1 Control Pane Info Menu ...............................................................................90

6.6 Toolbuttons ............................................................................................................ 90

6.7 Other Controls........................................................................................................ 91

Ch. 7 - Contact Mode Imaging 93

7.1 Overview................................................................................................................ 937.1.1 Special Hardware Requirements:..................................................................93

7.2 Startup .................................................................................................................... 937.2.1 Cold start.......................................................................................................937.2.2 Warm Start ....................................................................................................94

7.3 Approaching the Sample........................................................................................ 967.3.1 Aligning Laser and Performing a Manual Approach....................................967.3.2 Engaging .......................................................................................................98

7.4 Taking a Contact Mode Image............................................................................. 100

7.5 Taking Better Images........................................................................................... 1027.5.1 Before Beginning........................................................................................1027.5.2 Setting Scan Parameters..............................................................................1027.5.3 Adjusting Feedback Parameters..................................................................103

7.6 LFM Imaging....................................................................................................... 1057.6.1 Taking an LFM Image ................................................................................1067.6.2 How LFM Works........................................................................................108

Ch. 8 - TappingMode Imaging 113

8.1 Overview.............................................................................................................. 1138.1.1 Special Hardware Requirements.................................................................113

Table of Contents8.2 Startup .................................................................................................................. 114

8.3 Cantilever Tuning - Manual Tuning Method...................................................... 115

8.4 Autotune............................................................................................................... 123

8.5 Engage ................................................................................................................. 127

8.6 Scanning Windows .............................................................................................. 130

Ch. 9 - STM Imaging 135

9.1 Overview.............................................................................................................. 1359.1.1 Special Hardware Requirements.................................................................135

9.2 Preparing and Loading STM Tips ....................................................................... 1359.2.1 Using Wire Cutters to Make STM Tips......................................................1369.2.2 Using the STM Cartridge............................................................................1379.2.3 To Insert a Tip Into the STM Cartridge:.....................................................1389.2.4 To Store an STM Cartridge with a Tip Loaded: .........................................1399.2.5 To Remove a Tip from an STM Cartridge: ................................................139

9.3 Taking an STM Image ......................................................................................... 1409.3.1 Startup.........................................................................................................1409.3.2 Troubleshooting ..........................................................................................1429.3.3 Preparing for Engage .................................................................................1439.3.4 Engaging .....................................................................................................1449.3.5 Starting a Scan and Optimizing STM Scan Parameters .............................146

9.4 Considerations While Taking an STM Image ..................................................... 1489.4.1 Sample Characteristics................................................................................1489.4.2 Optimizing Image .......................................................................................1489.4.3 Increased Risk of Sample/Tip Damage ......................................................148

Ch. 10 - Single Point Spectroscopy 149

10.1 Overview............................................................................................................ 14910.1.1 Special Hardware Requirements...............................................................149

10.2 Startup ................................................................................................................ 149

10.3 Align Laser ........................................................................................................ 152

Table of Contents10.4 Engage ............................................................................................................... 153

10.5 Prepare to Ramp................................................................................................. 154

10.6 Ramp.................................................................................................................. 156

10.7 Sample Session with Probe Positioning............................................................. 158

Ch. 11 - MFM Imaging 161

11.1 Overview............................................................................................................ 161

11.2 Special Hardware Requirements........................................................................ 161

11.3 Startup ................................................................................................................ 162

11.4 Cantilever Tuning .............................................................................................. 16411.4.1 Manual Cantilever Tuning: .......................................................................16411.4.2 Cantilever Tune with Autotune.................................................................167

11.5 Engage ............................................................................................................... 168

Ch. 12 - EFM Imaging 173

12.1 Overview:........................................................................................................... 173


12.3 Startup ................................................................................................................ 174

12.4 Cantilever Tuning .............................................................................................. 176

12.5 Engage ............................................................................................................... 181

12.6 Set Tip Bias Voltage .......................................................................................... 184

Ch. 13 - Nanolithography 187

13.1 Overview:........................................................................................................... 18713.1.1 Special Hardware Requirements...............................................................187

Table of Contents13.2 Startup ................................................................................................................ 187

13.3 Additional Instructions and Information............................................................ 188

13.4 Nanolithography - A Sample Session................................................................ 188

Ch. 14 - Calibration 193

14.1 Overview............................................................................................................ 193


14.3 Test the X and Y Detector: ................................................................................ 194

14.4 Calibrating X and Y Measurements: ................................................................. 195

14.5 Calibrating Z Measurement: ............................................................................. 19714.5.1 Calibrating the Z-Linearizer: ...................................................................198

Ch. 15 - Thermal Tune 199

15.1 Overview............................................................................................................ 199

15.2 Set-up ................................................................................................................. 19915.2.1 Calibrate Sensitivity..................................................................................200

15.3 Thermal Tune..................................................................................................... 203

15.4 Additional Options............................................................................................. 20915.4.1 Input Gain .................................................................................................21015.4.2 Check for Aliases......................................................................................211

Ch. A - Synchronizer 213

A.1 Introduction:........................................................................................................ 213

A.2 Set-up .................................................................................................................. 214A.2.1 Handshaking Out-put Signals ....................................................................214A.2.2 Set Up Handshaking Input Signals ............................................................217

A.3 Configure Software ............................................................................................. 220

Table of ContentsA.4 Run Synchronizer................................................................................................ 222

Ch. B - Open Hardware 223

B.1 Introduction ......................................................................................................... 223

B.2 Software Setup .................................................................................................... 224

B.3 Open Hardware System Diagram........................................................................ 226B.3.1 Innova Systems Diagram ...........................................................................226B.3.2 Open Hardware Access Controls ...............................................................228

B.4 Input/Output Signal Access................................................................................. 229

B.5 Open Hardware Functions................................................................................... 229B.5.1 Feedback Control .......................................................................................229B.5.2 Multiplexer Control....................................................................................230B.5.3 DAC and ADC Control ..............................................................................235B.5.4 Tip/Sample Voltage Control ......................................................................236B.5.5 IOMod+ Control.........................................................................................238B.5.6 Innova Interface Board Control .................................................................240B.5.7 High Voltage Board Control ......................................................................241

B.6 Examples ............................................................................................................. 244B.6.1 Changing a Signal on a Channel ................................................................244B.6.2 Changing the Lock-in Output to Amplitude Times Cos (Phase) ...............246B.6.3 Turning on the 2kHz Low Pass Filter for a Measurement Channel...........247B.6.4 Z-Feedback on a Different or External Channel ........................................248B.6.5 Switching to Deflection Mode Feedback During Tapping Mode Imaging248B.6.6 Nanomanipulation at Contact Force...........................................................250B.6.7 Second-Harmonic Detection ......................................................................251

Ch. 1 - IntroductionOverview of Manual

Rev. B Innova User Manual - Ch. 1, Introduction 1

Chapter 1 Introduction

1.1 Overview of Manual

This manual provides information specific to the Innova system. This manual describes installation procedures and provides information on the operation of the SPMLab program. The information includes description of several modes of operation and imaging as well as real time data analysis. Some chapters are for reference only and describe modes and capabilities which are not included in the basic Innova system. Applications modules are required to obtain these additional capabilities.

Innova uses a stationary probe and samples are scanned back and forth beneath the probe. Typically, Innova samples are attached to round metal disks (pucks) which are magnetically attached to the top of the scanner tube. The scanner moves the sample in the x,y and z direction and the probe obtains information from the sample. The type of information will depend on the data channels chosen.

Figure 1.1a Innova system components

1.2 Safety

The Innova system is designed with features intended to safeguard operators from injury, prevent damage to the test samples and to be robust against damage from normal use. As with any electrical, mechanical device, some hazard is inevitable. Chapter 3 provides important safety information which should be read and understood by all users.

Dual MonitorsInnova

Isolation table

NanoDriveController

PC

Ch. 1 - IntroductionMicroscope Specifications

2 Innova User Manual - Ch. 1, Introduction Rev. B

1.3 Microscope Specifications

1.3.1 Special Hardware Requirements

Refer to the Veeco Probes catalog or visit www.veecoprobes.com for a listing and descriptions of the complete line of probes and other accessories.

1.3.2 Scanner Types

Two scanner options are available: Small Area and Large Area scanner

Figure 1.3a Scanner options

1.3.3 Scanning Techniques

Innova can operate in several SPM modes, including: Contact mode, TappingMode and STM. Many of these modes are listed below. Some of these modes employ Veeco proprietary methods.

• Contact Mode Imaging - Measures height by sliding a probe tip across and in contact with the sample in either air or liquid. LFM (Lateral Force Microscopy) characterizes frictional effects. See Chapter 7.

Small Area

Large Area

Ch. 1 - IntroductionMicroscope Specifications


• TappingMode Imaging (patented)- Measures height by tapping the surface with an oscillating tip. TappingMode eliminates shear forces that can damage soft samples and reduce image resolution. TappingMode is available in air and fluids. This is the technique of choice for most work and enables the use of phase imaging which can provide information about material properties such as adhesion and viscoelasticity. See Chapter 8.

• STM Imaging - Scanning Tunneling Microscopy. Utilizes tunneling current which varies with probe to sample separation for feedback to produce extremely high resolution imaging of flat conductive samples. See Chapter 9.

• Single Point Spectroscopy - Provides single point measurements for a detailed characterization of local electrical or mechanical properties. See Chapter 10.

• MFM Imaging - Magnetic Force Microscopy. Measures magnetic force gradient distribution above the sample surface. Performed using LiftMode (TappingMode height followed by a retrace with controlled spacing). See Chapter 11.

• EFM Imaging - Electric Force Microscopy. Measures electric force gradient distribution above the sample surface. Performed using an electrically biased probe in LiftMode (TappingMode height followed by a retrace with controlled spacing). See Chapter 12.

• Nanolithography - May use a probe tip to scribe or indent a sample surface by mechanical pressure or may employ anodic oxidation to alter the chemistry of the sample. Nanolithography is used to generate patterns, test for microhardness, etc. See the NanoPlot reference manual. See Chapter 13.

These imaging techniques are described in this manual. Additional information may be available in support notes (See Chapter 2). Contact Veeco if additional information is desired.

Ch. 1 - IntroductionSPM Fundamentals


1.4 SPM Fundamentals

1.4.1 Terminology

This section contains a brief list of terms and abbreviations to assist the reader. Other terms and abbreviations are referred to in the Index at the end of this manual.

AFM—Atomic force microscopy; atomic force microscope (see SPM).

bias—Electrical potential applied to a tip or sample which causes electron flow from one to the other.

calibration—Measurement of known features to ensure accuracy of SPM images.

cantilever—Flexible portion of probe extending from the substrate and to which the tip is attached.

cantilever tune—Process of finding a cantilever’s natural, resonant frequency by exciting the cantilever through a range of frequencies until maximum amplitude (resonance) is obtained.

DSP—Digital signal processor. Computer processor used to control SPM feedback loop.

drive amplitude—Amplitude of the signal used to oscillate a tip in TappingMode.

drive frequency—Frequency of the signal used to oscillate a tip in TappingMode.

engagement—Process of bringing a probe tip and sample together in a controlled manner such that useful information about the surface is obtained without damaging either the tip or the sample.

error—Difference between feedback signal value and feedback setpoint.

false engagement—Condition where probe is not racking the sample surface while in feedback. It may be caused by long range interactions or air damping. Selecting a more positive setpoint (contact mode) or smaller amplitude setpoint (TappingMode) may correct the problem

feedback—Process of self-correction of the error signal.

fluid cell—Accessory used for imaging materials in fluid.

integral gain—The multiplier of correction applied in response to the average error signal.

probe—The mechanical device (usually a integrated substrate, cantilever and tip) used for imaging.

probe holder—Removable appliance for mounting SPM probes.

proportional gain—The multiplier of correction applied in response to the error signal in direct proportion to the error.

PSPD - Position Sensitive Photo Detector. Produces output based on the position and intensity of a laser spot. The Innova AFM utilizes a quad photodetector (QPD) form of pspd.



QPD - Quad Photo Detector. A form of PSPD consisting of a four photodetector segment array. The output of each segment varies with the total intensity of the laser spot (or portion of laser spot) incident on the segment. The outputs of the four segments may be “summed or differenced” to determine the position of the laser spot on the array. In TappingMode operation, the laser spot oscillates across segment boundaries so the output of the QPD is an AC voltage.

RMS amplitude—Root mean square (RMS) signal measured at the detector. (TappingMode only.)

SPM—Scanning probe microscopy; scanning probe microscope. A general term encompassing all types of microscopy which utilize a scanned micro-sharpened probe and feedback circuitry to image nanoscale phenomena. SPM modes of operation include AFM, ECSTM, EFM, MFM, STM, and many others.

sensitivity—Amount of movement produced by a scanner piezo by a specific input voltage.

setpoint—Operator-selected threshold used as the target of the feedback control loop.

spring constant—Amount of force required to bend a cantilever a specific amount (typical units are N/m).

tipholder—See probe holder

1.4.2 SPM Overview

Figure 1.4a Contact Mode Detection Method



An atomic force microscope (AFM) operating in contact mode, touches the surface of a sample with a sharp tip (~2 µm long and often less than 5 nm radius), which is located at the free end of a cantilever 100-200µm long. The cantilever has a spring constant lower than the forces binding the atoms of the sample. As the scanner moves the sample under the tip, the contact force causes the cantilever to bend or deflect in response to changes in height.

A detection scheme measures the cantilever deflection as the sample moves relative to the tip. This detection scheme consists of a laser reflected off the back of the cantilever and onto a position sensitive photodetector (QPD). The measured cantilever deflections are used by the computer to generate a map of surface height.

1.4.3 The Feedback Loop

This section describes how the z feedback loop operates and introduces the feedback parameters that are adjusted to get the best images.

The z feedback loop operates to maintain tip-sample interaction at a target (setpoint) value. The signal at the QPD is compared to a reference signal (the setpoint value). The difference, or Error signal, is amplified by the gain parameters and then used by the feedback system to generate a voltage that is sent to the piezoelectric tube scanner. The voltage causes the scanner to extend or retract as needed to minimize the Error signal. Since the scanner position tracks the sample height, the signal sent to the scanner can be used to generate an image of height. The scan generator causes the scanner tube to move the sample in the x and y directions in a raster pattern.

The definitions of the probe signal and the reference quantity (the setpoint parameter) depend on the SPM mode being used. Various operating modes have been mentioned in section 1.3.3.

In Contact mode, the probe signal is the DC signal from the QPD (quad photo detector) that represents the vertical bending or deflection of the cantilever as the cantilever responds to surface height. The setpoint is the reference value for cantilever deflection (which relates directly to the force between the tip and the sample).

In TappingMode, the probe signal represents the amplitude of cantilever vibration. In these modes, the probe signal is determined from the AC signal from the QPD. The setpoint is the reference value for the amplitude of cantilever vibration.

In STM, the probe signal is the tunneling current. The setpoint is the reference value for the tunneling current.

In LFM, standard contact mode feedback is used while lateral force signals are monitored passively.



1.4.4 Scan Size, Scan Rate, Feedback Parameters (gains) and Setpoint

Scan and feedback parameters are adjusted to obtain satisfactory imaging which depends on obtaining a stable signal trace, free of noise or spurious signals. Iterative adjustment of some of the parameters described in this section is usually required to produce a high quality image. All parameters can be adjusted in real-time during a scan, without lifting the tip.

Scan Size

The scan size refers to the area of the sample which is being imaged. Since all scans are square, scan width alone is specified to set the scan size. The scan size selected depends on the features of interest and the size of the scanner.

For the standard Large Area scanner, the maximum scan size is >90 μm. When using the 10 μm grating included with the Large Area scanner, a scan size of 30 μm will display about three rows of the grating. With a scan size of 10 μm, only one row of the grating will be displayed.

A scan size may be chosen so that the features of interest are represented in reasonable proportions. For example, using a 1 μm calibration grating, a scan size of 5 to 10 μm will display several rows of the grating.

Generally, scan size should be selected to be greater than the lateral resolution multiplied by the number of data points per scan line, i.e., the spacing between the pixels should be larger or comparable in size to the area covered by each data point. Selecting a smaller scan size will result in adjacent data points containing redundant information.

Scan Rate

The scan rate sets the frequency of the back and forth rastering of the sample beneath the probe. Scan rate can be adjusted while acquiring an image. In general, as the scan size is increased, the scanning velocity also increases (a longer line is scanned at the same scan rate, so the tip travels faster over the sample). Large scan sizes usually are better imaged by decreasing the scan rate in order to decrease the tip to sample scanning velocity.

Generally, slower scan rates give better resolution because the feedback system has time to respond, while faster scan rates save time. If the scan rate is too fast, the feedback loop may not respond appropriately to changes in height. As a result, the image may appear smeared (poor surface tracking) or the tip may crash into protrusions on the surface, possibly damaging the tip and/or sample. The scan rate setting interacts with the gain setting (see the following section). The higher the gain setting, the faster the system can track the height and the faster the scan rate may be set and still obtain good images.

The scan rate also depends on the type of image being taken. For images of height using a scan size from 1 to 10 μm and with feedback enabled, typical scan rates are from 1 to 4 Hz.

To determine which scan rate is best for a particular set of scan conditions, take several scans at different rates and use a scan rate below the rate at which image quality begins to degrade.



Gain & Setpoint

How Z Feedback Works

When the feedback loop is optimized, the scanner motion matches surface height. The Z feedback loop operates to keep the cantilever deflection (in contact mode) constant by adjusting the Z position of the probe. The hardware components and signal pathways for Contact mode operation are shown in Figure 1.4b.

Figure 1.4b Hardware components and signal pathways for contact mode.

The cantilever deflection is compared to the setpoint value in the setpoint scrollbox (the reference value for the z feedback loop), and an error signal is generated. The error signal is sent to the feedback electronics, which generates a feedback voltage. This feedback voltage controls the scanner tube, causing it to extend or retract. The probe to sample spacing is controlled to maintain a constant cantilever deflection which minimizes the error signal. The feedback signal can be used to generate an image of sample height.

Gain

The magnitude of the error signal is often insufficient to cause the z scanner to respond properly. To obtain better response, a gain is specified. The gain (of the feedback loop) is a multiplier applied to the Error signal to generate the feedback signal to the scanner. This parameter must be optimized for each set of scan conditions. Higher gain values mean that the feedback loop is more responsive to changes in deflection of the cantilever. Proper gain settings are required for good imaging.

If the gain is too high, the feedback signal will over react to small changes and the system will oscillate. Feedback oscillations appear on the signal trace as fringes or ripples. If the gain is set too low, the z feedback will not track surface height properly. When surface tracking is poor, surface features can appear lopsided or the tip can damage features on the surface or be damaged by the sample.

Deflection Signal

DeflectionSetpoint



Set gain by beginning with the default value. Gradually increase the value until the system begins to show oscillation and reduce the gain until the oscillation ceases. An acceptable gain setting usually will lie within a range of settings rather than at a single value.

Figure 1.4c shows the signal trace on the Profile Display in the scanning window. As the gain is increased from the default value, the contours of the grating lines will be reestablished on the Oscilloscope Display.

Figure 1.4c The signal trace on the oscilloscope display.

As the gain is increased further, oscillations and overshoots appear superimposed on the signal trace of the grating as shown in Figure 1.4d. Gain should be reduced until the overshoots and oscillations disappear.

Figure 1.4d Feedback optimized



When scan conditions change (for instance, at different portions of the sample), the gain parameter should be verified as still optimized. If oscillations appear, lower the gain until the system is just below the oscillation point.

Setpoint

In contact imaging mode, setpoint represents the amount of cantilever bending, or deflection. High setpoint produces higher contact force between the tip and sample in contact mode. When the z feedback loop is enabled, the system operates to keep the amount of cantilever bending constant by moving the sample up or down. In TappingMode, setpoint represents the amplitude of cantilever oscillation. High setpoint produces lower contact force between the tip and sample and because the oscillation is less affected by interaction with the sample. The high setpoint relates to a high RMS voltage resulting from higher amplitude oscillation of the cantilever. The remainder of this discussion deals with contact mode setpoint. Additional discussion of TappingMode setpoint is contained in Chapter 8.

The optimal value of the setpoint parameter depends on a number of factors, the most influential is the sample. If horizontal streaking occurs in an image, the setpoint is too high (the cantilever is exerting more force against the sample surface), and “dirt” (unidentified particles, material, etc.) is being dragged on the sample. If streaking remains after reducing the setpoint value, the sample is probably too soft to examine using contact mode -- or a softer cantilever may be needed. Setpoint can be adjusted during a scan so that its effect may be observed in real time. When optimizing the setpoint, it is useful to compare the forward and reverse traces on the oscilloscope display, as described in Chapter 7.

If the setpoint is too low, the probe will not be able to track the sample height. Check the signal trace on the profile display in the scanning window to see if it realistically represents the height. When imaging the calibration grating with a setpoint value that is too low, the shape of the signal trace will appear to flatten out, indicating that the probe is unable to follow the height.

Number of Data Points

The number of data points contained in an image can be specified: 16 x 16, 32 x 32, 64 x 64, 128 x 128, 256 x 256, 512 x 512, or 1024 x 1024. The default is 512 x 512.

In general, a larger number of data points results in higher resolution. For example, for the same scan size, a 512 x 512 image contains 64 times the number of data points as a 64 x 64 image and therefore has a higher resolution, however, collecting a 512 x 512 image takes more time.

Note: An efficient way to increase the resolution of an image is to zoom in on a smaller region to take a scan. This increases the number of data points per scan size.



1.4.5 Main menu items

Scan Size

Scan size—Size of the scan along one side of a square.

X and Y Offsets

X offset; Y offset—These controls allow selection of the center of the area to be scanned.

Scan Angle

Scan angle—Combines X-axis and Y-axis drive voltages, enabling the piezo to scan the sample at variable X-Y angles.

Scan Rate

Scan rate—Sets the number of lines scanned per second.

Leveling

Leveling is used when the average surface of the sample is not parallel to the scanning plane. The leveling options are:

• None

• 1DAC - subtracts the average from the signal for each line

• 1D line fit - subtracts a 1st order least mean square fit for each line

• 1D bow removal - subtracts a 2nd order least mean square fit for each line

• 2D AC - subtracts the average for all the date acquired at the time

• 2D plane - plane tilt removal for all data acquired at the time

Taking Images in Low Gain Mode

CAUTION: The high gain range is ~0 to 400 volts and the low gain range is ~0 to 100 volts. If switching from high gain to low gain mode, avoid damage to the probe tip and sample in by raising the Z stage a short distance using the z direction pad to ensure that the probe tip clears the sample surface.



Both high- and low-gain modes are available on Innova. High gain mode accommodates most applications. Low gain mode produces the best noise performance for ultra flat samples a atomic resolution with the large area scanner. It is not usually necessary to select the low gain mode when using the small area scanner.

High gain mode applies the full voltage range to the scanner to produce xy and z motion and is most often used for scan sizes in the micron range. The maximum scan size in high gain mode is limited by the available range of scanner motion. The maximum xy range of a Large Area scanner is nominally 90 μm. The maximum z range of a Large Area scanner is nominally 7.5 μm.

Low gain mode uses only a portion of the scanner xy and z range and is generally used for smaller scans—on the order of tens to hundreds of nanometers. The range of xy motion is reduced to ~1/4 of its full range, and the range of z motion is reduced to ~1/3 of its full range. For example, the xy range of a Large Area scanner is reduced to ~25 μm, and the z range is reduced to ~2.5 μm.

This section explains why low gain mode is important for obtaining improved lateral resolution with smaller scan sizes and gives step-by-step instructions for switching from high gain to low gain mode.

Using Low Gain Mode for Lateral Resolution

Low gain mode can be useful to look at smaller features on a sample. Without low gain mode, it would not be possible to obtain the highest lateral resolution (below approximately 50 nm) for small scan sizes.

The main factors limiting the lateral resolution of images are:

• the scan size divided by the number of data points per scan line

• the effective tip radius

• the x-y detector resolution (if Closed Loop is enabled)

• the scan DAC resolution

If a 10 μm image is taken with 256 x 256 data points, then one data point is taken every 10 μm/256, or 39 nm, which represents the limit of the lateral resolution. Lateral resolution will be better by a factor of 2 for a 10 μm image taken with 512 x 512 data points, however, it will take twice as long because there are twice as many lines of data.

In order to improve the lateral resolution as limited by the scan size without increasing the time to take an image, use a smaller scan size. For example, for a 256 x 256 image and a scan size of 50 nm (0.05 μm), the lateral resolution limit improves to 50 nm/256, or 0.195 nm.

The lateral resolution is no better than the largest limiting factor. For small scan sizes (below 5 μm), the largest limiting factor is not likely to be the scan size divided by the number of data points per scan line. In general, do not select a scan size that is smaller than the lateral resolution (as limited by any of the factors described here) multiplied by the number of data points per scan line. Selecting a smaller scan size will result in adjacent data points containing redundant information.



In most cases, the primary limiting factor to the lateral resolution is the interaction area between the tip and the sample, or the effective tip radius. The interaction area is affected by type of imaging being performed, the characteristics of the surface being imaged (height, chemistry, surface fluids, field effects). The sharpness and geometry of the tip also influence the interaction area and lateral resolution.

In STM mode, the exponential relationship between tunneling current and tip-to-sample spacing isolates the interaction between the tip and the sample to atoms at the very end of the tip. Thus, even a very blunt tip with a radius on the order of 100 nm can be used in STM mode to achieve atomic resolution when the tip has a single atom that protrudes more than its neighbors. This same tip, however, may not be able to resolve features that are wide if those features are also very deep (high aspect ratio features).

For other modes, the lateral resolution as limited by the effective tip radius is on the order of nanometers to tens of nanometers. Factors such as tip wear and deformation increase the interaction area for contact mode operation. The response of the measured signal to changes in tip-to-sample spacing affects the lateral resolution for tapping (lift) modes. The way to determine the smallest features that can be imaged using a particular tip in a particular operating mode is to optimize all of the other factors that limit the lateral resolution and then experiment imaging small features on a sample.

Assuming a small scan size and good tip conditions, the factor next most likely to limit the lateral resolution is the resolution of the x-y detector, which is on the order of 1 nm. This limit applies only if Closed Loop is on. Thus, the highest lateral resolution for small scan sizes is obtained with Closed Loop off.

Note: Closed Loop is not available with small area scanners.

Finally, the digitized step size of the scanner limits the lateral resolution. The voltage applied to the scanner is digitized, and the number of possible voltage values depends on the number of bits of the digital-to-analog converter (the DAC) used to send the voltage signal to the scanner. Innova uses 20-bit DACs for sending the voltage signal to the scanner, so the voltage can be expressed as a 20-bit number, which has 220 possible values. The total range of motion of the scanner can therefore be divided into 220 digitized steps. In low gain mode with a Large Area scanner, the minimum step size of the scanner is 25 μm/220 steps = ~0.025 nm/step. For a Large Area scanner and a 20-bit digital-to-analog converter, the resolution as limited by the step size of the scanner is always 0.025 nm -- substantially smaller than the length of a typical chemical bond.

The feedback controls and displays used to optimize operation of the Z feedback loop are listed in the following table and are described in the later sections



.

1.4.6 Z Position Bar: Monitoring the Scanner's Position

The Z Position bar is a tool for monitoring the scanner extension and retraction in response to the feedback voltage. It is displayed on the left side of the main SPMLab window. The Z Piezo bar is shown in the figure below.

Figure 1.4e The Z Piezo bar.

Control Function

Z Position Bar Graphically represents the scanner z position within the total range of scanner motion and the working range of the scanner for the last line of data collected.

Feedback signal Graphically represents the probe signal and setpoint values.

Setpoint Specifies the reference signal for the z feedback loop. In contact mode, the setpoint sets the vertical force between the probe and the sample that results in cantilever bending. For STM, the setpoint sets the tunneling current between the probe and the sample. In TappingMode, MFM and EFM, the setpoint sets the amplitude of cantilever vibration.

PID Gains Specifies the gains (multipliers) applied to the feedback signal for proportional, integral and derivative feedback.

Feedback Box When highlighted and checked indicates feedback is active. Used to turn the z feedback loop on and off. When the feedback loop is off, the Z position check scrollbox allows the scanner to be extended or retracted.

Cartoon Window Displays the cantilever/tip status (withdrawing, engaging, engaged)



The bottom end of the Z Position bar represents the scanner's position when it is fully retracted. The top end of the Z Piezo bar represents the scanner's position when it is fully extended. The scanner tube retracts when the probe tip encounters peaks in the surface and extends when the tip encounters valleys in the sample surface.

1.4.7 Feedback Signal: Monitoring the Feedback Signal and Setpoint Values

The Feedback Signal bar is displayed to the left of the Z Position bar. The Probe Signal bar is a graphical representation of the setpoint value and the probe signal. The numerical value of the setpoint parameter is displayed in a scrollbox above the probe signal bar. The Probe Signal bar is illustrated in Figure 1.4f. The appearance of the bar may vary depending upon the SPM operating mode.

Figure 1.4f The Feedback Signal bar.

1.4.8 Setpoint: Setting the Reference Signal for the Feedback Loop

The setpoint scrollbox is used for specifying the setpoint, which is the reference signal for the feedback loop that is maintained during an auto engage and a scan. For Contact mode, the setpoint represents cantilever deflection, or force between the tip and the sample. For TappingMode, MFM and EFM, the setpoint controls the amplitude of cantilever vibration. For STM, the setpoint represents tunneling current. For LFM, the setpoint value also has an effect on the lateral force due to friction. Increasing the setpoint value increases the force between the probe tip and sample. The allowed range of values of the setpoint depend on the operating mode and the system calibration parameter values.

In general, the setpoint value is increased (i.e., the value becomes more positive) the distance between the probe and the sample decreases. In contact mode, increasing the setpoint value decreases the tip-to-sample spacing in order to achieve a greater cantilever deflection, or vertical force, between the probe and the sample. For STM, increasing the setpoint value, brings the probe and the sample surface closer together to produce a higher tunneling current. During a scan, a signal from the feedback loop is sent to the scanner, causing the scanner to retract or extend so that



the feedback signal matches the setpoint value. For TappingMode, increasing the setpoint value results in a higher amplitude and a lower amount of force applied to the sample.

To enter a setpoint value: Enter a new value in the setpoint scrollbox and then press the [Enter] key. Or, use the scrollbox arrows to scroll through a range of values. The increment of the scroll box can be changed by double clicking inside the scroll box.

1.4.9 Setting the Gain of the Feedback Loop

Feedback is required to correct piezo positioning to accommodate changes in the sample. The gain parameters control how much the feedback signal is amplified before being sent to the scanner. The range of gain values is in arbitrary units scaled with the scanner z range of motion.

The optimum values for the gain parameters depend on a number of factors, including the scan rate, the scan size, and the sample height. Higher gain values make the feedback loop more sensitive to changes in the feedback signal. Usually, surface features can be tracked more closely when higher gain values are used, however, if gain is set too high, the feedback signal will fluctuate in overreacting to small changes.

CAUTION: Do not lower the gain to zero. When the gain is set to zero, the feedback loop is disabled, and the system will not track changes in surface features. If the feedback is completely disabled, the tip can be damaged if the sample surface is very rough. For STM, some finite feedback response is needed to prevent the tip from crashing into the sample.

To adjust gains: Enter a value in the Gain scrollbox and then press the [Enter] key. Or, use the scrollbox arrows to scroll through a range of values.

Integral, Proportional and Derivative Gain

These settings affect the response time of the feedback loop. The feedback loop adjusts the z piezo voltage to minimize the error signal (difference between the setpoint value and actual value). Piezoelectric transducers have a characteristic response time to the feedback voltage applied. The gains are multipliers of the feedback error signals. The large (multiplied) compensation causes the piezo scanner to move faster in Z and compensates for the mechanical hysteresis of the piezo element. The effect is smoothed because the piezo receives feedback at four or more times the rate of the image display. The integral feedback signal is based on the sum of previous errors (this method will correct a continuing set of errors too small to be corrected by other feedback methods). The proportional feedback signal is based on the difference between the current signal and the target. The derivative feedback signal is based on the difference between the current error signal and the preceding error signal. The gains are multipliers for each of these feedback signals but the units for gain are arbitrary. In most cases, the integral gain value has the largest effect in optimizing feedback behavior in scanning probe microscopy.



1.4.10 Feedback Checkbox: Setting the Scanner's Z Position

The Z feedback toolbutton is used to enable or disable the z feedback loop. The feedback loop is enabled when the toolbutton is engaged and disabled when not engaged. When the feedback loop is disabled, a Z position scrollbox is displayed below the toolbutton. This scrollbox may be used to manually extend or retract the scanner. Z position may be used to monitor the scanner position. By default, the scanner extension is in microns (µm).

The primary uses for manual control of the z position of the scanner are lithography and manipulation. Refer to the NanoPlot manual for additional details

To manually extend or retract the scanner: Unclick the feedback toolbutton. The Z(µm) scrollbox should be displayed below the checkbox. Enter a value in the Z position scrollbox and then press the [Enter] key, or use the scrollbox arrows to scroll through a range of values. Monitor scanner extension on the Z Piezo bar.

CAUTION: Be careful when using the Z(µm) scrollbox to manually extend the scanner. Extending the scanner too far will cause the probe to crash into the sample surface. A probe crash can damage the probe, the scanner, and the sample.



Rev. B Innova User Manual - Ch. 2, Advanced Imaging 19

Chapter 2 Advanced Imaging

2.1 Advanced Imaging

The standard configuration of Innova has the ability to produce nanoscale images using Contact mode, TappingMode and STM (Scanning Tunneling Microscopy) mode for many sample types in a typical laboratory environment. Lateral force microscopy and phase imaging are included in the standard configuration and provide contrast mechanisms based upon material properties. These capabilities give access to information beyond simple topography. Optional enhancements for the Innova system provide additional capabilities including the capability of probing additional material properties as well as enabling operation in a fluid and/or temperature controlled environment to perform imaging of samples under relevant conditions (viz. biological samples, electrochemical reactions, etc.).

This section provides brief descriptions of several advanced imaging modes and accessories, however, development continues to produce additional methods and improve existing ones. To order any of the options or to obtain information on these items or more recently developed methods, contact your Veeco representative.

Advanced ImagingAdvanced Methods:

20 Innova User Manual - Ch. 2, Advanced Imaging Rev. B

2.2 Advanced Methods:

2.2.1 Scanning Thermal Microscopy (SThM)

Description

The Scanning Thermal Microscopy (SThM) package for Innova provides the capability of imaging thermal conductivity (using conductivity contrast mode) and sample temperature (using temperature contrast mode). The principle component of the SThM package is a thermal probe with a resistive element. Thermal monitoring and control are performed by the Thermal Control Unit (TCU). In conductivity contrast mode, the thermal probe is kept at a constant temperature. Changes in sample thermal conductivity affect the heat flow between the self-heating probe and the sample. This heat flow is monitored by measuring the voltage necessary to maintain a constant probe temperature. In temperature contrast mode, temperature is monitored using a bridge circuit to measure the probe resistance.

The SThM package consists of:

• Box of SThM probes

• Thermal Control Unit (TCU)

• BNC cable to connect the Thermal Control Unit to the NanoDrive Controller.

• BNC-type cable to connect the Thermal Control Unit to the thermal probe

• 15V Power supply

• Cable to connect the power supply to Thermal Control Unit

• Test sample for conductivity contrast imaging

Option Part Number: INST-3

Support Note Number: 013-426-000



2.2.2 Conductive AFM (C-AFM)

Description

Conductive Atomic Force Microscopy (C-AFM) is a secondary imaging mode derived from Contact mode that characterizes conductivity variations across semiconducting materials and across conducting or semiconducting material covered with a thin dielectric layer (on the order of a nanometer). C-AFM performs general-purpose measurements, and has a current range of sub pico amperes (pA) to micro amperes (µA). The current amplifier can also support mA current levels although these are rarely used in C-AFM analyses. C-AFM employs a conductive probe tip. Typically, a DC bias is applied between the tip and the sample. While the z feedback signal is used to generate a normal Contact mode topography image, the current passing between the tip and sample is measured to generate the conductive AFM image which shows the conductivity variations of the materials under test.

The Conductive AFM Imaging package includes:

• Unmounted conductive imaging chip carrier with BNC connector

• Low current amplifier and power supply

• Amplifier mount

• C-AFM cable

• 10 MΩ surface-mount resistor sample

• 10 SCM-PIC unmounted Pt/Ir coated probes

Option Part Number: INCA-3

Support Note number: 013-427-000



2.2.3 Liquid Imaging:

Description

The MicroCell Kit enables imaging in liquids. Imaging of samples in liquid is a growing application of AFM technology. This growth derives from a desire to minimize surface forces on delicate samples, the need to observe biological specimens in their natural, fluid environments. Imaging samples under fluid can eliminate attractive forces due to surface tension. This enables the sample surface to be imaged with a minimum of cantilever tip force, which is advantageous when imaging biological specimens and delicate materials. The need to observe biological samples in liquid is readily understood since the property and dynamics of many living structures can be preserved only under conditions that are as close as possible to their natural states. A separate accessory is available for electrochemical AFM and STM applications (refer to Electrochemistry: Section 2.2.10).

The MicroCell kit consists of the following components:

• MicroCell

• Open liquid cell

• 1ml syringe

• Plastic tubing

• Viton rubber shrouds

• Innova scanner shield

• Chip mounting fixture

• Spare glass

• Unmounted AFM Probes

Option Part Number: INLC-3




2.2.4 Electrostatic Force Microscopy (EFM)

Description

Electrostatic Force Microscopy (EFM) is a secondary imaging mode derived from TappingMode imaging. EFM maps the electrostatic force gradient above the sample surface. Mapping is performed using a patented two-pass technique, LiftMode. LiftMode separately measures topography and another selected property (magnetic force, electric force, etc.) with the two-pass procedure. During the first pass, the probe tip is controlled to track the surface so that topographical information is obtained. During the second pass, the topographical information is used to move the probe tip along the same track but keep it at a constant height (Lift Height) above the sample surface.

In EFM, a voltage bias is applied to the probe tip. While scanning, the cantilever resonance frequency or phase is influenced by the tip to sample separation. The influence of electrostatic force is measured using the principle of force gradient detection. EFM can be used to image both naturally occurring static charge domains and deliberately DC biased structures.

A more complete description of EFM operation is contained in Chapter 12

The following items are required for Innova EFM operation:

• TappingMode cartridge

• Unmounted probe chip carrier (00-107-0142)

• Probe: conductive tips required, ie., DDESP, MPP-11150-10, etc.

The EFM package includes:

• Unmounted chip carrier for EFM

• Sample bias holder for optional external bias

• 10 SCM-PiT Pt/Ir coated probes

• EFM test sample

Option Part Number INEF-3




2.2.5 Magnetic Force Microscopy (MFM)

Description

Magnetic Force Microscopy (MFM) is a secondary imaging mode derived from TappingMode imaging. MFM maps the magnetic force gradient above the sample surface. MFM is performed using a patented two-pass technique, LiftMode. LiftMode separately measures topography and another selected property (magnetic force, electric force, etc.) with a two-pass procedure. During the first pass, topographical information is obtained. During the second pass, the topographical information is used to move the probe tip along the same track but keep it at a constant height (Lift Height) above the sample surface as determined during the first pass.

In MFM, the probe tip is coated with a ferromagnetic thin film. While scanning, it is the magnetic force that induces changes in the cantilever resonance frequency or phase. MFM can be used to image both naturally occurring and deliberately written domain structures in magnetic materials.

A more complete description of MFM operation is contained in Chapter 11.

The following hardware items are required for Innova MFM operation and are included in the MFM Tool Kit:

• 10 MFM probes (MESP)

• MFM tip magnetizer

• Non-magnetic sample holder

• MFM test sample

Option Part Number: INMF-3




2.2.6 Force Modulation Microscopy (FMM)Description

Force Modulation Microscopy enables collecting simultaneous topographic and material-properties data. Force Modulation Microscopy is based on Contact mode feedback integrated with phase imaging and can serve to complement TappingMode phase imaging. Specifically, the force modulation mode offers both amplitude and phase detection for mapping variations in the mechanical properties of a sample surface. Surface elasticity, adhesion, and related properties may be analyzed. Variations in composition can also be distinguished, based on differences in surface properties.

The Force Modulation Package consists of the following components:

• FM Cartridge probe holder (p/n: 860-012-714)

• TiO2 paint chip sample (p/n: 00-110-1106)

• Also needed to perform FMM (not included in package) are probes suitable for FMM such as FESP.

Option Part Number: INFM-3


2.2.7 Low Current STMDescription

The Low Current STM option extends the STM capability included in the default configuration of Innova to permit STM imaging samples which produce lower tunneling currents than are needed to produce acceptable images using the default capability. Current noise levels below 1.0 pA can be achieved. The low current STM option requires the (separate) purchase of the C-AFM option (see Conductive AFM (C-AFM): Section 2.2.2).

The Low Current STM package includes:

• LCSTM Cartridge

• 10 STM probes (Pt/Ir)

Option Part Number INLO-3




2.2.8 Scanning Capacitance Microscopy (SCM)

Description

SCM characterizes the capacitance properties of the sample and provides a means for 2D dopant profiling. The images are useful in analyzing doped semiconductor materials where the dopant distributions are not readily determined by other means. The SCM option offered with Innova provides a fully integrated hardware and software solution which maximizes setup efficiency. The option includes closed-loop SCM Imaging to ensure a constant depletion volume.

The Innova SCM package includes:

• SCM sensor

• SCM cartridge

• SCM probes (SCSI-ptmt-cp)

• SCM Cable

• SCM sensor fixture

• PI expansion board (installed in Nanodrive controller by Veeco personnel)

Option Part Number INSC-3


2.2.9 Piezo Response Microscopy

Description

Piezo Response Microscopy (PZR), also known as piezoresponse force microscopy (PFM) characterizes the local piezoelectric properties of a sample. An AC bias voltage is applied between tip and sample during contact mode imaging with a conductive tip. The Magnitude and phase of the response are recorded. The piezo response option is fully integrated in hardware and software so that no external devices are required.

Option Part Number: INPR-3




2.2.10 Electrochemistry

Description

The Innova Electrochemistry option permits in situ Contact mode or STM studies of surfaces in a controlled electrochemical environment. The electrochemistry option combines an electrochemistry cell and probe cartridge designed for Innova and uses the VersaSTAT-3 potentiostat from Ametek/Princeton Applied Research.

Scans and electrochemical measurements can be taken simultaneously. An electrochemical measurement can be interrupted or altered without affecting the progress of the scan, and a scan can be interrupted or altered without affecting the electrochemical measurements. The V3 Studio electrochemical software provided with the potentiostat displays the data in real-time in a window separate from the SPMLab screen. This window can be hidden in the background while still controlling the potentiostat.

The following components are included in the Electrochemistry option:

• Electrochemistry probe cartridge

• Open electrochemistry cell with protective scanner cover

• VersaSTAT3-200

• V3 Studio Electrochemical software package, installed in Innova computer

• Potentiostat to Innova cable

• Package of Unmounted MicroLever Probes (MLCT-AUNM)

Option Part Number:

• INEC-30 - includes potentiostat

• INEC-31 - does not include potentiostat


2.2.11 Surface Potential Microscopy (Kelvin Probe Microscopy)

Description

Surface Potential Microscopy (SPoM) or Kelvin Probe Microscopy (KPM) allows the determination of the local electrostatic potential of the sample surface. This is achieved by applying a combination of AC and DC bias such that the cantilever response at frequency ω of the AC bias

Advanced ImagingAccessories and documents


drives the magnitude and sign of the applied DC bias. The implementation of surface potentiol microscopy on Innova is exceptionally well integrated in hardware and software, yet exceptionally flexible. Dual-frequency, single-pass potential measurements are enabled by the 2 full lock-in amplifiers integrated in the control electronics. This approach minimizes topographic artifacts by matching the electrostatic potential while in feedback. Additionally, Veeco’s patented Lift Mode can be employed in a dual-pas, single-frequency approach to maximize the signal-to-noise ratio of the potential measurement.

Option Part Number: INSP-3


2.3 Accessories and documents

2.3.1 Heater Cell

Description

The heater components are used to heat the sample to a desired temperature within the range of ambient to 60ºC.

The Heater kit consists of:

• A 60ºC heater element

• Thermal Applications Controller

Option Part Number: INHTR-A60


Ch. 3 - SafetyOperating Safety

Rev. B Innova User Manual - Ch. 3, Safety 29

Chapter 3 Safety

3.1 Operating Safety

This section includes important information about the Innova system. It describes procedures related to the operating safety of Innova and must be read and understood before operating the Innova system.

WARNING: The protection provided by the Innova system may be circumvented if the procedures described in this User Guide are not followed. Personal injury or equipment damage may result.

3.1.1 Safety Symbols

Table 3.1a lists symbols that appear throughout this User Guide and on the Innova system. Become familiar with the symbols and their meanings. The symbols are used to emphasize operating safety matters of the Innova system.

Table 3.1a Safety Symbols and Functions.

SYMBOL FUNCTION

Direct current source

Alternating current source

Direct and alternating current source

Three-phase alternating current

Ground (earth) terminal

Protective conductor terminal


30 Innova User Manual - Ch. 3, Safety Rev. B

3.1.2 Definitions: Warning, Caution, and Note

There are three terms that are used in this Uses Guide related to the operating safety of Innova: Warning, Caution, and Note. These terms are defined in Table 3.1b.

It is important to read all warnings, cautions, and notes. Warnings, cautions, and notes include information that are important to the operating safety of Innova system.

Frame or chassis terminal

Equipotentiality

Power on

Power off

Equipment protected by double or reinforced insulation

Refer to system documentation

Electric shock risk

Table 3.1b Safety Terms and Definitions.

TERM DEFINITION

WARNING Alerts of possible serious injury. Do not proceed beyond a warning until conditions are fully understood and appropri-ate actions taken.

CAUTION Calls attention to possible equipment or facility damage.Note Emphasizes or provides additional information.

Table 3.1a Safety Symbols and Functions.

SYMBOL FUNCTION



3.1.3 Summary of Warnings and Cautions

This section includes warnings and cautions that must be followed whenever operating Innova.

WARNING: Innova must be properly grounded before applying power. The mains power cord must be inserted into an outlet with a protective earth ground contact.

WARNING: The line voltage selection must be checked before applying power to Innova system components. The line voltage selector switch is on the front panel of the NanoDrive beneath the front cover and protective clear shield. The line voltage selector switches can be set to the following voltages: 100 V, 120 V, 220 V, and 240 V. See section 3.1.5.

WARNING: Do not open Innova. The NanoDrive and the base unit use hazardous voltages and therefore present serious electric shock hazards.

WARNING: Periodically inspect the cables of the Innova system to ensure they are not frayed, loose, or damaged. Cables that are frayed, loose, or damaged must be reported immediately to a local Veeco service representative. Do not operate Innova when wires are frayed, loose, or damaged.

WARNING: Do not connect or disconnect cables or components when power is applied. Physical injury and/or equipment damage may result.

CAUTION: All Innova system components must be handled with care. System components contain delicate electromechanical components that can be damaged easily by improper handling.

CAUTION: The power to the NanoDrive must be turned OFF before removing or installing the scanner.

CAUTION: When removing and installing the scanner, personnel and equipment must be grounded to ensure that the scanner is not damaged. The scanner is sensitive to electrostatic discharge.

CAUTION: The four screws that connect the scanner to the base unit must be securely fastened to ensure proper grounding. When the four screws are securely fastened vibrations are reduced and maximum instrument performance is ensured.

CAUTION: To preserve safety and EMC compliance, Innova must be used with the EMI filter supplied with the Innova system.

CAUTION: Operation of Innova without the cover may reduce EMC.



3.1.4 Grounding Innova

Innova must be properly grounded before applying power to its components. The main power cord must be inserted into an outlet with a protective earth ground contact. If there is no access to an outlet with a protective earth ground contact, the Innova system must be grounded using the ground connection of the NanoDrive. The location of the ground connection is shown in Figure 3.1a.

Figure 3.1a NanoDrive Rear Panel, Showing Ground Connection.

3.1.5 Setting the Line Voltage

The line voltage selection must correspond to the line voltage of the facility where the Innova system is operated. The line voltage selection is made by setting 6 voltage selectors. These selectors are located beneath the front cover of NanoDrive. The available line voltage settings are: 100V, 120V, 220V, or 240V.

To change the line voltage selection:

1. Ensure the power switch to the NanoDrive is turned off.

2. Unplug the NanoDrive power cord from the power outlet or back panel.

3. Remove the front cover.

Ground Connection

Ch. 3 - SafetyLaser Safety


4. Remove the clear shield cover protecting the line voltage selector switches.

Figure 3.1b NanoDrive Voltage Selectors

5. Set the line voltage on each of the six (6) selectors to the desired value: 100V, 110V, 220V, or 240V.

6. Replace the clear plastic shield and front cover.

The line voltage is now set to the appropriate value.

3.2 Laser Safety

Innova contains a diode laser powered by a low voltage supply with a maximum output of 0.2 mW CW in the wavelength range 600 to 700 nm. Diode laser power up to 0.2 mW at ~670 nm could be accessible in the interior. Innova should always be operated with the probe head properly installed.

(Front cover and clear plastic shield have been removed)

Selector switches (6)

Power On/Off

Ch. 3 - SafetyLaser Safety


WARNING: Use of controls or adjustments or performance of procedures other than those specified herein could result in hazardous laser light exposure.

Figure 3.2a shows the warning labels located on the Innova probe head. Strict observance of these warning labels is required.

Figure 3.2a Warning Labels on the Probe Head.

The Caution label in Figure 3.2a specifies that the probe head is a Class II laser product.

The aperture label is located in the cutout cavity of probe head and indicates that laser light is emitted from the aperture indicated.

Ch. 3 - SafetySpecifications and Performance


Figure 3.2b shows the location of the laser safety compliance label on the rear panel of the NanoDrive electronics module.

Figure 3.2b NanoDrive Rear Panel, Showing Location of Laser safety Compliance Label.

3.3 Specifications and Performance

System Configurations

Probe Head Operates in Contact mode, TappingModeand STM modes.

Measurement Performance

StandardScanner Large Area (>90 μm) piezoelectric scanner.Scan range Maximum lateral scan range: >90 μm.

Maximum vertical scan range: 7.5 μm.

Ch. 3 - SafetySpecifications and Performance


OptionalScanner Small area piezoelectric scanner.Scan range Maximum lateral scan range: 5 μm.

Maximum vertical scan range: 1.5 μm.

Microscope Stage

Translation range 6 mm x 6 mm.Sample size ~45 mm x ~45 mm x 18 mm (thick).Tip-sample approach Automatic with 3 independent stepper motors.Optical microscope Optional on-axis microscope with color video

monitor for probe tip and sample view. 5:1 zoom, ~250 μm field of view.Standard 10X objective.

System power 115/230 V AC, 50/60 Hz, 600 W.

Dimensions and Weights

Innova 15 in. (380 mm) x 14 in. (355 mm) x 14 (355 mm); 26 lb (12 kg).NanoDrive 14 in. (585 mm) x 23 in. (191 mm) x

23 in. (585 mm); 50 lb (23 kg).Computer 17 in. (432 mm) x 7.5 in. (191 mm) x

17.5 in. (445 mm); 27 lb (12 kg).

Operating Environment

Temperature 0°C to 30°C, 32°F to 112°F.Humidity 60%; non condensing.

Cleaning Agents

Base unit Isopropyl alcohol.Probe head Isopropyl alcohol.AEM and computer Isopropyl alcohol.

WARNING: To avoid risk of electric shock, do not clean Innova system components when power is applied.

CAUTION: Do not use acetone to clean Innova system components. Acetone may damage important safety warning labels.

Ch. 3 - SafetyInnova User Documentation


3.4 Innova User Documentation

3.4.1 Innova User’s Guide

Innova User manual is a complete guide to operating the Innova instrument in: Contact mode, TappingMode, STM, MFM and EFM modes. It provides an overview of the instrument system, including important safety information, and provides all the necessary steps for setting up the instrument and performing imaging and single point spectroscopy in air and in liquid. The manual describes how to perform scanner calibration procedures and provides a brief tutorial in Nanolithography using the Nanoplot applet.

3.4.2 SPMLab Display and Image Analysis

Document 004-1006 provides description and instruction on use of the analysis capabilities in the Image Analysis application portion of the SPMLab software. Some of the capabilities are: surface flattening, distance measurements, FFT analysis and many others.

Ch. 3 - SafetyInnova User Documentation


Ch. 4 - Installation and Set-UpOverview:

Rev. B Innova User Manual - Ch. 4, Installation & Setup 39

Chapter 4 Installation and Set-Up

4.1 Overview:

This chapter describes how to prepare the Innova instrument to take an image in Contact mode, which is used for imaging the height of a sample. The sample in these tutorials is the 10 µm calibration grating provided with the Large Area scanner. The sample has been selected because its features are relatively easy to identify.

Further details and background information related to many of the procedures in this chapter are provided in Chapter 7 and Chapter 8.

This chapter assumes familiarity with Chapter 1. Before following the procedures in this chapter, also ensure that:

• The Innova instrument has been properly installed by a Veeco representative.

• The computer components and control electronics, have been installed and set up properly.

• The cables are properly connected between the system components and the power cords are plugged in.

WARNING: This instrument contains a laser. Use of controls or adjustments or performance of procedures other than those specified in this manual could result in hazardous laser light exposure.

4.2 Facilities

The basic requirements for facilities, including utilities and floor space requirements are listed in this section. Innova is designed to operate acceptably in what would be considered a typical laboratory environment in terms of temperature and humidity. A user supplied vibration isolation table (VT-GB or equivalent) is required for Innova and critical applications may require additional protection against mechanical or acoustic vibration (including air buffeting).

Ch. 4 - Installation and Set-UpFacilities

40 Innova User Manual - Ch. 4, Installation & Setup Rev. B

4.2.1 Acoustic/Vibration Specifications

The following conditions must be met in order to achieve 1.0 angstrom RMS noise specifications:

• Acoustic: Acoustic noise should not exceed 75dBC (Note “C” weighting).

• Vibration: Vibration of the AFM mounting surface should not exceed VC-D in any direction.

Figure 4.2a Vibration Criteria Plot

4.2.2 Space requirements

The following diagrams depict the minimum space requirements for the Innova system components. An additional minimum of 6” (15 cm) is recommended around the controller and SPM to provide adequate cooling airflow. The PC is a standard tower (mini or midi) configuration. The PC and the PC system components (keyboard, mouse, monitors) are commonly used components and are not discussed in this section. Innova must be mounted on a suitable vibration isolation table but all other components may be placed on “normal” furniture and the NanoDrive is commonly placed directly on the floor or a small riser.

Velo

city

Lev

el in

dB

re 1

mic

ro-in

ch/s

ec

One-Third Octave Band Frequency in Hz

Workshop (ISO)

Residential Day (ISO)

Perception Threshold (ISO)

Operating Theater (ISO)

BBN Criterion A

BBN Criterion B

BBN Criterion C

BBN Criterion D

BBN Criterion E

32,000

16,000

8,000

4,000

2,000

1,000

500

250

125

100

90

80

70

60

50

16

20

25

31.5

40

50

63

80

100

125

1604

5

6.3

8 12.5

10

Office (ISO)

BBN Criterion A - Probe Test Equipment. 100X MicroscopesBBN Criterion B - 500X Microscopes. Aligners, Steppers to 5m GeometriesBBN Criterion C - 1000X Microscopes. Aligners, Steppers to 1.5m GeometriesBBN Criterion D - Steppers, E-Beams to 0.3m Geometries, CD Inspection Equipment. Most SEMs to 50,000XBBN Criterion E - Anticipated Adequate for Future Fabrication and Test Equipment for Low Submicron Geometries

1959-940-A

40

Ch. 4 - Installation and Set-UpFacilities


Innova

Figure 4.2b SPM Space Requirement

NanoDrive

Figure 4.2c Controller Space Requirement

Ch. 4 - Installation and Set-UpCable Connections


4.3 Cable Connections

The cable connections described in this section should have been made by the authorized Veeco representative who initially installed the system. Nevertheless, it is prudent to perform a check by noting the following steps, which will also serve as familiarization with the system.

Figure 4.3a Cable Connections for Innova System Components.

1. Ensure that all system components are turned off.

2. Set up the computer components, including the keyboard, mouse, and monitor.

a. Connect the keyboard cable to the keyboard connector on the back panel of the computer unit.

b. Connect the mouse cable to the mouse connector on the back panel of the computer unit.

Ch. 4 - Installation and Set-UpCable Connections


c. Connect the computer monitor cables to the computer monitor connectors on the back panel of the computer unit.

3. Connect the Veeco supplied USB cable between the NanoDrive Controller and the back panel of the PC.

4. Connect the 68 pin Low Voltage cable between the low voltage connector on the back panel of the Innova microscope and the low voltage connector on the IO-I board of the NanoDrive Controller. This cable carries low voltages signals (e.g. the setpoint) to the Innova instrument.

5. Connect the 13 pin High Voltage cable between the high voltage connector on the back panel of the Innova microscope and the high voltage connector on the IO-HV board of the NanoDrive Controller. This cable carries high voltage signals that are applied to the piezoelectric scanner.

6. Connect the 50-pin motor control cable between the motor control connector on the back panel of the Innova instrument and the NanoDrive controller. The motor control cable carries low-voltage signals to the stage.

7. Connect the video cable from the video BNC connection at the back panel of the Innova microscope to the frame grabber card connector at the back of the PC.

Figure 4.3b NanoDrive Cabling Locations

Ch. 4 - Installation and Set-UpRemoving and Installing the Scanner


4.4 Removing and Installing the Scanner

CAUTION: The scanner is extremely fragile. The piezoelectric ceramic tube is easily broken/damaged by mechanical shock. Use extreme care when handling the scanner. Do not apply any pressure to the sample holder on the top surface of the scanner since this may result in scanner tube damage/breakage

CAUTION: Ensure the head is not installed and the optics are moved out of the way before removing or installing the scanner.

CAUTION: The power to the NanoDrive must be turned OFF before removing or installing the scanner.

Figure 4.4a Scanner

To remove the scanner:

1. Move the optics out of the way.

2. Remove the Innova head.

3. If a sample is loaded, remove it from the sample holder.

4. Turn off the software

5. Turn off the NanoDrive controller

6. Loosen the four hex-head capscrews at the corners of the scanner using a 3/32" allen wrench.

7. Lift the screws to verify that they are not engaged (the screws are captive with the scanner and will not be entirely removed. See Figure 4.4b.

Sample holder above Scanner tube

Mounting Screws (4)

Connector

Ch. 4 - Installation and Set-UpRemoving and Installing the Scanner


Figure 4.4b Cover and Head Removed to Expose Scanner.

8. Taking care to avoid damaging the scanner, pry the scanner up using the fingerholds on the left and right sides of the scanner to disconnect the electrical connector from the Innova stage. Using the allen wrench in the loosened screw, the scanner may be pried up very gently. As a third alternative, remove the scanner by pulling the screws (use two diagonally opposite screws).

CAUTION: Do not allow the top of the scanner—especially the sample holder—to come into contact with another surface. If the scanner contacts another surface, the scanner tube may break.

9. After the electrical connector is disengaged, lift the scanner and tilt it to remove it from the Innova stage.

10. Store the scanner on its side in the box originally supplied.

To install a scanner:

1. Insert the four hex-head screws into the scanner (as required).

2. Orient the scanner to align the scanner connector with the stage connector and insert the scanner into the opening on the Innova stage. There is only one correct fit. The scanner should fit snugly.

CAUTION: The four screws that connect the scanner to the Innova base unit must be securely fastened to ensure proper grounding. When the four screws are securely fastened, vibration is reduced and imaging is improved.

Scanner Mounting Screws (4)

Ch. 4 - Installation and Set-UpStarting Innova


3. Tighten the four hex-head screws with a 3/32" allen wrench until the scanner is firmly seated.

Note: Whenever the scanner is changed, the system software must be reconfigured to be consistent with the hardware.

4.5 Starting Innova

1. Turn the computer and monitors on. The computer on/off switch is located on the front panel of the computer unit. The computer monitor on/off button is located on the front of the monitor below the screen. Windows starts automatically and displays the desktop.

2. Turn on the NanoDrive. The on/off rocker switch is located on the lower left portion of the front panel of the controller.

3. From the Windows START button, select All PROGRAMS→VEECO→SPMLAB XP→ SPMLAB or double click the desktop icon for SPMLab.

To Remove the Probe Head:

1. Rotate the swing arm of the Innova Optics to move the objective lens away from the probe head before moving the stage.

2. Use the motor stage controls to provide clearance between the probe and the sample.

3. If a probe cartridge is installed in the probe head, it can be removed by grasping the handling prong and sliding the cartridge out of the head, as shown in Figure 4.5a.

Figure 4.5a Removing the Probe cartridge from the Probe Head.

Ch. 4 - Installation and Set-UpLoading a Sample


4. Set the probe cartridge on a flat surface with the cantilever facing up.

5. Disconnect the electrical connector from the stage before removing the head.

Figure 4.5b Removing the Probe Head

6. Place the probe head on a flat surface or in its original box.

To install the probe head

1. Place the head on the three point motor stage mounts.

CAUTION: Ensure that the head is properly seated on the three point mount.

2. Insert the electrical connector from the probe head into the connector on the stage, as shown in Figure 4.5b.

4.6 Loading a Sample

1. Move the Innova Optics objective lens away from the probe head by rotating the swing arm.

Connector

Ch. 4 - Installation and Set-UpLoading a Sample


CAUTION: The objective lens must be out of the way before loading a sample. Otherwise, raising the probe head will hit the objective lens, damaging both the probe head and the lens.

2. Open the Motors Stage window either by clicking the toolbutton or using the menu as shown in Figure 4.6a.

Figure 4.6a Menu to Open Motors Stage Window

3. Use the up arrow in the Motor Stage window to raise the probe head to provide ample clearance for loading the sample.

Figure 4.6b Motor Stage Window Control to Position Probe Height

4. Secure the sample to one of the sample mounting disks supplied with the instrument.

CAUTION: Do not let the sample mounting disk snap down hard on the magnetic sample stub. The piezoelectric scanner (mounted underneath the sample holder) is a ceramic material that can easily break under mechanical shock.

Raise probe

Lower probe

Note: The Motor Stage window may be displayed in “Simplified or “Extend”ed form by clicking

Simplified

Extended the corresponding toolbutton.

Ch. 4 - Installation and Set-UpInstalling a Chip Carrier


5. Slide the mounting disk gently onto the sample holder (the small round stub attached to the top of the scanner) as shown in Figure 4.6c.

6. Position the mounting disk so that the sample is centered on the sample holder. The sample holder magnet holds the sample mounting disk securely in place.

Figure 4.6c Sliding the Sample Mounting Disk Onto the Sample Holder.

7. Use the down arrow in the Motor Stage window, refer to Figure 4.6b to lower the probe head to within several millimeters of the sample surface.

8. Move the Innova Optics objective lens into position over the sample.

4.7 Installing a Chip Carrier

The chip carrier, with pre-mounted cantilever probe, is installed on the probe cartridge. The size of the cantilevers in Figure 4.7a is greatly exaggerated. The probe cartridge is then installed in the probe head.

Figure 4.7a Microfabricated cantilever Chip Mounted on Chip Carrier.



Figure 4.7b The AFM Probe Cartridge

The spring clip on the cartridge holds the slots in the chip carrier securely against the three balls in the three-point mount of the probe cartridge. The spring clip has two small notches for the prongs of the spring clip tool.

A special spring tool, shown in Figure 4.7c, must be used to lift the spring clip for removing and installing a carrier.

Figure 4.7c The Spring Tool.

Note: The spring tool should be kept in a secure place when not in use. If the tool is lost, a charge will be made for a replacement.

1. Place the probe cartridge on a flat surface with the handling prongs facing to one side and the spring clip facing up.

Contact for Head (3x)

Chip Carrier

Handling prong

Spring clip



CAUTION: Hold the chip carrier by the ceramic plate. Do not touch the microfabricated cantilever chip. The cantilever chip is extremely fragile and can be damaged or broken easily.

2. Remove a new chip carrier from the box of chip carriers.

3. Ensure that the cantilevers have not broken off.

4. While holding the chip carrier, also hold the probe holder so that it will remain steady as the chip carrier is inserted.

5. Place the chip carrier near the three-point mount, as shown in Figure 4.7d.

Figure 4.7d Lifting the Spring Clip.

6. Place the spring tool prongs under the spring clip, as shown in Figure 4.7d. The curved side of the tool prongs should face down, and the flat side of the prongs should engage the notches in the spring clip.

7. Gently lift the spring clip by pressing down on the handle of the clip tool.

CAUTION: Do not bend the spring clip beyond its normal range.



8. Slide the chip carrier under the lip of the spring clip, as shown in Figure 4.7e, until the balls engage the slots.

Figure 4.7e Inserting the Chip Carrier.

9. Wiggle the chip carrier from side to side to ensure that all three balls fit snugly. A correctly installed chip carrier is shown in Figure 4.7f.

Figure 4.7f Correctly Inserted Chip Carrier.

10. Raise the handle of the spring clip tool to lower the spring clip to clamp the chip carrier.

11. Disengage the spring tool from the notches in the clip spring, and put the tool in a secure place.

Ch. 4 - Installation and Set-UpLoading a Probe Cartridge


4.8 Loading a Probe Cartridge

CAUTION: Use only approved probe cartridges in the Innova head. An incorrect probe cartridge may damage the instrument.

A chip carrier should be installed in the probe cartridge, as described above.

1. Grasp the probe cartridge by the handling prong.

2. Insert the probe cartridge into the probe head with the tip facing downward.

3. Ensure the probe cartridge clicks into place in the probe head (indicating that the 3-point contacts are positioned correctly).

4.9 Using the WinTV32

WinTV displays an image of the sample seen through the optical microscope of Innova. The following instructions show how to enable the Innova Optics and WinTV32.

4.9.1 Using the Innova Optics

This procedure assumes that the Innova Optics and the video monitor are properly installed and that a probe head, a chip carrier, and a sample are already loaded.

CAUTION: A stop inside the swing arm limits the arm rotation. Rotate the swing arm slowly to avoid striking the probe head in the event that it or the head is not properly adjusted.

1. Rotate the Innova Optics swing arm slowly until the objective lens fits between the two arms of the probe head.

2. The lens should be positioned directly over the cantilever and sample.

Ch. 4 - Installation and Set-UpUsing the WinTV32


3. Start WinTV32 by Start > All Programs > Hauppauge WinTV > WinTV32.

Figure 4.9a Start WinTV32 Directions

4. The sample will be illuminated with light from the Innova Optics. The video monitor representation will brighten and display a blurry image.



5. Zoom out to the widest field of view by moving the camera slider control fully to the left and adjust the light intensity by sliding the light intensity control to obtain the best possible image.

Figure 4.9b Light and Zoom Slide Controls

Figure 4.9c Innova Optics Controls.

CAUTION: Coarse focus moves the lens up and down. To avoid damaging the probe head and the lens, do not drive the objective lens down into the probe head.

6. Adjust the coarse and fine focus adjustments to focus on the sample, refer to Figure 4.9c.

Light intensitycontrol slider

Camera slider

Optics Swing Arm

Focus knobs

X-directionY-direction

Optics Stage Adjustments

FineCoarse



7. Monitor the focus adjustment by looking at the WinTV display. The cantilever chip with triangular-shaped cantilevers should be seen.

Figure 4.9d WinTV View of Cantilevers

8. Adjust the position of the cantilever until it is approximately centered in the view by using the two optics stage position adjustments attached to the Innova Optics support plate to move the Innova Optics relative to the base. See Figure 4.9e.

Figure 4.9e Stage Adjustments

9. Using the stage adjustments may cause the optical image to wobble. The Innova instrument has built-in vibration isolation so the wobble will stop after making micrometer adjustments.

10. Adjust the fine focus using the small focusing knob (see Figure 4.9c) until the cantilever is clearly visible and in focus.

Ch. 4 - Installation and Set-UpAligning the Deflection Sensor


4.10 Aligning the Deflection Sensor

4.10.1 Aligning the Laser Spot

Aligning the laser spot involves adjusting the laser spot onto the cantilever and then positioning the reflected laser spot onto the desired portion of the QPD. The deflection sensor scheme is described in SPM Overview: Section 1.4.2.

WARNING: Use of controls or adjustments or performance of procedures other than those specified may result in hazardous laser light exposure.

1. Ensure that the power to the probe head is on.

2. Turn the LASER ON/OFF switch to ON.

Figure 4.10a Laser On

3. Use the laser (cantilever) alignment controls (Figure 4.10b) to move the laser beam spot onto the cantilever chip. An intense red reflection indicates the laser spot is at the front of the cantilever chip above the cantilever.

Ch. 4 - Installation and Set-UpAligning the Deflection Sensor


4.10.2 Aligning the Deflection Sensor

Figure 4.10b Probe Head Alignment Controls and Laser Indicators.

1. Focus on the cantilever with the Innova Optics.

2. Adjust the laser spot to the end of the cantilever.

3. Center the laser spot on the end of the cantilever.

4. Adjust the QPD (Detector) alignment knobs to align the laser spot while watching the laser position indicators on the front of the probe head (see Figure 4.10b). The central green LED should be brightly illuminated and none of the red LEDs illuminated. It is normal to make several adjustments, alternating between up/down and left/right to obtain proper alignment. Near the correct position, the red lights are very sensitive, and some practice is needed to make the adjustments so that all the red lights are off.

Figure 4.10c QPD Alignment LED Indicators

QPD Laser

Head

Head

5 LEDs (center green)

Ch. 4 - Installation and Set-UpTroubleshooting Tips


4.11 Troubleshooting Tips

• Aligning the QPD may be especially difficult if the probe is defective. Residual strains may cause a cantilever to bow and make alignment difficult. It may be advisable to replace the probe.

• If it is not possible to position the laser properly on the detector, insure the probe is properly mounted or attempt aligning to the second cantilever.

• The laser power is not on. -- Ensure that the head is properly connected to the stage and check that the LASER ON/OFF toolbutton in the main window is clicked ON.

• The laser spot doesn’t come into view in the optics. -- It is important to ensure that the laser spot is in the vicinity of the cantilever. Move the optics out of the way and adjust the laser positioning controls until the spot can be seen near the cantilever.

• It isn’t clear what direction the steering knobs move the laser spot. -- Observe the position of the spot on the sample surface and experiment with the knobs.

• The brightness of the laser spot on the cantilever in the optical view is maximized, but the laser intensity indicator does not illuminate. -- Do not try to maximize the brightness of the laser spot in the optical view. The goal is to maximize the reflected light to the QPD. When the spot is positioned so that the QPD is receiving the maximum reflected light, the laser spot on the cantilever may not appear bright in the optical view.

• The cartridge is not properly inserted in the probe head. -- Wiggle the cartridge in and out to ensure that all three contact zones are engaged by the three balls on the cartridge. The cartridge should feel firmly mounted when it is correctly positioned over the contact zones.

• The chip carrier is not properly inserted in the cartridge mount. -- Remove the cartridge from the head and wiggle the chip carrier from side-to-side to ensure that all three balls on the cartridge mount are engaged by the three slots on the chip carrier. The chip carrier should “click” into place.

• The cantilevers are broken. -- Examine the probe either visually or using the optical microscope view to determine if the cantilever(s) are broken. Replace the probe as required.

4.12 Typical startup

1. Power should be applied to the system components in the following sequence:

a. PC

b. Monitors (2)

c. Controller (which supplies power to the microscope)

Ch. 4 - Installation and Set-UpTypical startup


2. To start the SPMLab software, double-click the SPMLab startup icon on the computer desktop. Select Yes when asked to load DSP Code, see figure Figure 4.12a. The SPMLab software window appears and may span one or two monitor displays. This large window will contain all the areas and panels needed to control the microscope and analyze results.

Figure 4.12a System Status

3. After the DSP code is loaded, the System Configuration Window will appear. Select the appropriate microscope and scanner. The example in figure Figure 4.12b shows Tapping selected.

Figure 4.12b System Configuration Example

The SPMLab and controller systems allow up to 20 simultaneous image channels.

4. Select the scanner (Scanners).

5. Select Apply after inputting all microscope parameters.

Ch. 4 - Installation and Set-UpTypical startup


6. Select Yes when asked to “Would you like to turn the HV on”.

7. The main SPMLab window, Figure 4.12c displays the toolbuttons for all functions and feedback controls in the left portion of the window.

Figure 4.12c Main SPMLab Window

Note: Individual sections may be turned on/off by right clicking on the left toolbar which will open a selection window for the sections to be displayed.

Figure 4.12d Section Selection Window

Function toolbuttons

Laser on/off

Feedback controls

Optical Microscope light and intensity

Camera zoom

Engage Indicator

Tip bias controls

Ch. 4 - Installation and Set-UpDeflection Sensor


4.13 Deflection Sensor

The probe head must detect extremely small movements of the cantilever as it interacts with the surface of the sample. A deflection sensor measures these movements. The deflection sensor reflects a laser beam off the back of the cantilever onto a position-sensitive photodetector (QPD). This technique is known as “beam bounce” detection. As the cantilever bends, the position of the laser spot on the QPD shifts. The shift in spot position indicates how much the cantilever has deflected. In most implementations, the laser beam is directed (“aimed” or “positioned”) by adjusting mirrors to locate the beam and spot as required. (Refer to Figure 4.13b.) For proper Contact mode operation, two conditions must be met:

1. The laser spot must be positioned on the end of the cantilever as shown in Figure 4.13a.

2. The intensity of the reflected laser beam at the QPD must be above a certain level.

Figure 4.13a Correct Laser Spot Position.

When the laser spot is properly aligned on the QPD, the laser intensity indicator on the front of the probe head is bright green, and none of the red laser position indicators are illuminated. It is possible to accidentally align the deflection sensor with the laser spot reflecting off one of the legs of the cantilever, the cantilever chip, or the sample surface. Under these conditions, the alignment indicators may show the deflection sensor is aligned properly, but the instrument will not work properly.

4.13.1 Alignment Knobs

The deflection sensor is aligned while the probe is not in contact with the sample surface, i.e., before performing an approach. When the deflection sensor is properly aligned, the laser beam reflects off the back of the cantilever and onto the correct position on the QPD. The Innova probe head uses two adjustable mirrors to position the laser beam in the deflection sensor: the cantilever mirror and the detector mirror. The cantilever mirror positions the laser beam onto the cantilever and the detector mirror positions the reflected beam from the cantilever onto the QPD.



The angle of each positioning mirror can be changed with two sets of alignment knobs shown in Figure 4.13b.

Figure 4.13b Probe Head Alignment Controls

The laser (cantilever) alignment knobs position the laser spot onto the cantilever. The laser spot moves in the direction indicated by the arrows on the up/down (U/D) knob and the left/right (L/R) knob.

The QPD (detector) alignment knobs position the laser spot onto the QPD deflection sensor. The laser spot moves in the direction indicated by the arrows on the up/down (U/D) knob and the left/right (L/R) knob.

HeadHead

(QPD)(Laser)Detector

Cantilever



4.13.2 Laser Indicators

The laser position and intensity indicators located on the probe head are shown in Figure 4.13c and Figure 4.10c. The indicators display the results of the mirror adjustments made with the alignment knobs.

Figure 4.13c Laser Position and Intensity Indicators.

(red)

(red)

(red)(red)

(green)



The Laser Alignment window in the SPMLab program provides a visual representation of the laser

spot on the QPD. Open the Laser Alignment window either by clicking the toolbutton or using the menu as shown in Figure 4.13d.

Figure 4.13d Menu Selection for Laser Alignment Window

Fine align the laser using the laser alignment window indicator, Figure 4.13e and use the adjustments on the head (ref. Figure 4.13b) to adjust the laser spot location (the pink spot) to the center of the window.

Figure 4.13e Image of Centered Laser Spot

The voltage readout on the bottom left indicates the voltage sum of the four quadrants of the QPD and indicates the intensity of the reflected spot -- a large value is desirable (depending upon the cantilever, values between 0.5 and 5V are typical). The values on the axes indicate lack of centering of the spot -- values near zero are desirable.

Ch. 4 - Installation and Set-UpMotor stage controls


4.14 Motor stage controls

The motor stage window is used to control the distance between the probe and the sample. If the probe is too close to the sample, it may be dragged across the sample and damage both the probe and the sample. To avoid damaging either the probe or sample, set the probe to sample distance to provide a safe clearance. Probe spacing can be adjusted using the controls in the Motors stage panel.

Figure 4.14a Motors Stage Panel

Motor speed is adjusted by selecting Fast, Middle or Slow. Alternatively, enabling the Distance scroll box and inputting a value in the input box permits incremental Z motion by the input value when clicking the up or down toolbuttons.

The four quadrant arrow toolbuttons in the Control Mode portion of the window are used to align the scanning plane and sample. By clicking on the arrows, pitch and roll can be adjusted.

The Stage Reset tool causes the stage to return to its default level position. Whatever tilt or roll is inherent in the sample or sample mounting is ignored.

CAUTION: Frequent or repeated use of Stage Reset may cause a safety shutdown due to controller overheating. Stage motors will be disabled (several minutes) until the controller temperature is restored to a safe range.

Select to enabledistance scroll

Ch. 4 - Installation and Set-UpEngage


4.15 Engage

Approaching the sample is a two-part process. First, the motor stage controls (as described in section 4.14) are used to perform a manual approach to move the probe close to the sample surface. Then, auto engage is used to bring the probe to the distance required for imaging. When an auto engage has succeeded, the probe is said to be “in feedback” at the surface. The greater the distance between probe tip and sample, the longer the auto engage process will require.

The Engage dialog box is shown in Figure 4.15a in two configurations. The configuration can be changed between “Simplify” and “Extend” by clicking the toolbutton in the lower right of the window.

Figure 4.15a The Engage Panel

• The engage process involves adjusting the sewing voltage, the motor step (0.4 µm min.) and the delay time (delay between motor step and sewing range).

• The settings for these parameters are specified in the “Extend” window, however, the default values will generally produce good results.

• The Z Center checkbox causes the piezo range to be set at midrange after an autoengage has been completed and the probe is in feedback.

• The Auto Scanning checkbox causes scanning to occur immediately following a successful engage (the probe scans but no data is produced).

• The piezo/tip interaction distance can be adjusted manually using the 2 step buttons (up and down). A right mouse click opens a window where the desired Z adjustment can be entered.

Autoengage

Stop engage/ Disengage

“Simplify Window”

“Extend Window”

Ch. 4 - Installation and Set-UpEngage


• Clicking the down arrow in either window initiates an automatic approach/engage using the settings which are in the “Extend” window.

• To autoengage, stop the engage process or disengage, click the appropriate toolbutton as

indicated in Figure 4.15a. Right clicking on the disengage tool opens a window where the retreat step distance may be entered.

Ch. 5 - Realtime ControlsThe Scanning Control Dialog Window:

Rev. B Innova User Manual - Ch. 5, Real Time 69

Chapter 5 Realtime Controls

5.1 The Scanning Control Dialog Window:

Figure 5.1a Main Scanning Window

The scanning control window controls all the real time parameters used for scanning an image. The main window supports 3 scanning options:

1. Area scanning (highlight square)

2. Line scanning (highlight line box)

3. Point probe positioning (highlight point probe icon)

5.2 Area Scanning

The area scan window allows setting of:

• Number of data points: (min. = 16x16 pixels, max = 1024x1024 pixels).

Ch. 5 - Realtime ControlsArea Scanning

70 Innova User Manual - Ch. 5, Real Time Rev. B

• Scan rate: sets the number of lines scanned per second in the x direction. (min. = 0.1 Hz, max = 100.0 Hz).

• Scan range: size of the scan along one side of a square (min. = 0 µm, max = 5.0 µm for 5.0 scanner and 90 µm for 90 µm scanner).

• Rotation: combines x and y drive voltages such that the piezo scans the sample at variable x –y angles (scanning angle 0 to 360).

• X and Y offset: these controls allows entering an offset of x and y from the center of the full xy scan range.

Figure 5.2a Profile and Power Spectrum

The profile and power spectrum display shows typical parameters for an area scan of a 10.0 µm grid. The profile shown on the figure depicts a height vs. scan range plot for the current line being scanned. The vertical axis can be scaled automatically by selecting the A button or manually set by highlighting either the X2 or divide /2 button. The power spectrum which describes how the power of the signal is distributed with frequency can be displayed by highlighting the “power spectrum button”. The scales for the power spectrum display can be adjusted with the tools on the right hand side of the screen (log, auto, x2 or divided by 2).

Automatic

PowerSpectrumTool

Scan Area Tool

Divide by 2Multiply by 2

Scaling

Ch. 5 - Realtime ControlsLine Scanning


Once an image has been obtained, measurements can be made as follows:

1. Select the scan area toolbutton at the top of the scanning window. See Figure 5.2a.

2. Drag the image from the image window to the scan area window. See Figure 5.2a and Figure 5.3a.

3. Use the tools on the right hand side of the window to measure squares, distance or angles. See figure Figure 5.3a.

5.3 Line Scanning

Any line scan can be obtained from a scanned image. Line scans can be obtained as follows:

1. Highlight the scan area icon on top of the scanning window.

2. Drag the image from the image window into the scan area window in the scanning window.

Figure 5.3a Image Dragged Into Scan Area Window

Ch. 5 - Realtime ControlsLine Scanning


3. Click on the Line Scan toolbutton . Draw the line for the scan in the scan area window. The line scan window will appear. Select the channels desired by clicking the acquire icon.

Figure 5.3b Scan Line Drawn

Line Scan tool

Drawn line

Ch. 5 - Realtime ControlsScanning Window Tools


4. Level the Line Scan signal by selecting a leveling option (AC only, 1D 1st order or 1D 2nd order) And press start in the main scanning window.

Figure 5.3c Scan Leveled

5.4 Scanning Window Tools

A toolbar is on the right side of the Scanning window and contains five (5) toolbuttons (see Figure 5.4a) which are used to obtain information about the scanned image/sample.

1. Click the Area Scanning toolbutton to activate area scanning instead of line scanning.

Leveling Options

Start scan



2. The Zoom toolbutton is used to select a portion of the scan to be enlarged. After clicking on the toolbutton, click and drag a square on the desired portion of the scanned image as illustrated in Figure 5.4a.

Figure 5.4a Zoom Area Selected

Toolbuttons

Zoom Toolbutton



3. Right click in the center of the zoom square to display the zoomed image of the selected area.

Figure 5.4b Zoomed (Magnified) Image.

4. Press the Start scan tool to perform a new scan of the selected area.

5. To revert to the original scan area, click the UndoZoom toolbutton .

6. The Distance Measurement toolbutton is used to perform linear distance measurements on the scanned image.



7. After selecting the Distance Measurement toolbutton, click and drag a measurement line on the scanned image and the distance will be displayed as shown in Figure 5.4c.

Figure 5.4c Distance Measurement Line Drawn with Click and Drag

8. The Angle Measurement tool permits angular measurements to be made on the scanned image.



9. After selecting the Angle Measurement tool, click and drag a line for one side of the angle, then right click and drag the other side of the angle to display the angle as shown in Figure 5.4d.

Figure 5.4d Angle Measurement

10. The Cross Section toolbutton is used to produce the height along a specified line analogous to a cross section.

11. After selecting the Cross Section toolbutton, click and drag to define a line on the image for cross sectioning.

12. When the line has been drawn, the Cross Section window will open and display the sample height along the line.

Figure 5.4e The Cross Section Window

Ch. 5 - Realtime ControlsProbe Positioning


13. Clicking on the cross section plot at points of interest (see the blue triangular markers in Figure 5.4e) will display information about the markers and their relative positions.

5.5 Probe Positioning

1. Select the probe position icon Move the cursor to the desired probe position. The coordinates will appear on the left hand side of the scanning window.

Figure 5.5a Probe Position

2. A circle will appear to indicate the current probe position.

3. Click and drag the circle to reposition the probe.

4. For addition information on probe positioning, refer to Chapter 10.

Probe position

Ch. 5 - Realtime ControlsLiftMode Settings


5.6 LiftMode Settings

The scanning window contains real time controls for the LiftMode. The LiftMode is used in MFM and EFM and will be described in detail in Chapter 11 and Chapter 12.

1. Figure 5.6a shows the LiftMode window for MFM.

Figure 5.6a LiftMode for MFM

2. The (four) parameters to specify are: start height, lift height, start delay and end delay. This mode also allows the user to turn off the laser or disable the Tapping Drive on the lift trace.

Ch. 5 - Realtime ControlsLiftMode Settings


3. Figure 5.6b shows the LiftMode window for EFM. The parameters in the LiftMode section are the same as used with MFM. Select the Double Bias tab, select Enabled and choose to apply a voltage bias to either the tip or the sample and enter the appropriate bias voltages.

Figure 5.6b LiftMode for EFM

4. Figure 5.6c shows the selection window that allows one to ground the sample or tip during forward or backward trace.

Figure 5.6c Selection Window

Ch. 5 - Realtime ControlsScanning Conditions Window


5.7 Scanning Conditions Window

The high gain and low gain settings are selected from this window. The low gain settings should be used for atomic scale imaging with the large area scanner. There is also a HV on/off button. Additionally overscanning (% of maximum) and x and y scanning movements can be selected in this window. If the synchronizer option has been enabled, the synchronizer control will show up on the right side of the scan conditions window.

Figure 5.7a Scanning Conditions

5.8 Point Spectroscopy Window

This window allows specifying parameters for measuring: Signal distance curves, IV curves (signal vs. bias voltage) and to turn on/off the z linearizer and thresholds. Figure Figure 5.8a shows a typical signal-distance curve. The following parameters can be specified:

• Resolution (number of data points, the minimum is 16 pixels, maximum 1024 pixels).

• Z start and Z end.

• Approach and retreat rate

• Cycle Hold time

• Thresholds

Ch. 5 - Realtime ControlsIV Curves


• Cycle hold time

Figure 5.8a Point Spectroscopy Signal-Distance

5.9 IV Curves

1. The signal current to voltage curve (bias line on tip or sample) is generated in the Point Spectroscopy window. The following inputs may be made but the default values will usually produce good results:

• Resolution (number of data points, the minimum is 16 pixels, maximum 1024 pixels)

• Approach and retreat rates

• Z Start/End range

• Cycle hold time

• Bias line (tip or sample)

• Thresholds - Trigger on deflection or height signals

2. The scaling for the graphs displayed on the right are adjusted by selecting full, auto or manual on the left and right signal scales.

Ch. 5 - Realtime ControlsSignal Tracing Window


5.10 Signal Tracing Window

The Signal Tracing window allows a plot of a channel as a function of a driving signal. See Figure 5.10a.

Figure 5.10a Signal Tracing Window

5.11 Probe Position Window

1. Scan an image and drag the image to the scan area of the Scanning window.

Figure 5.11a Image Dragged from Channel to Scanning

Image channels

Image from Tapping Amplitude - Backward draggedinto Scanning window

Ch. 5 - Realtime ControlsProbe Position Window


2. Open the Probe Positioning window by clicking the Probe position toolbutton .

3. Select the Probe toolbutton to add individual locations, the Line toolbutton to add

a line of locations or the Frame toolbutton to add a 2D array of locations.

4. The selected probe positions will be shown in the image and listed by coordinates in the probe location window.

Figure 5.11b Probe Positioning

Coordinates of selected points

Selected points on image

Ch. 6 - MenusFile Menu

Rev. B Innova User Manual - Ch. 6, Menus 85

Chapter 6 Menus

The menu bar contains a list of menus. Menus contain menu items that provide access to instrument controls. The menus and menu items of SPMlab are depicted in the figures below.

6.1 File Menu

Figure 6.1a File Menu

Menu item Function

Save data Saves a copy of the images acquired. It is necessary to specify the filename and location to save the file

Exit Exits the program and returns to the desktop

Ch. 6 - MenusSetup Menu

86 Innova User Manual - Ch. 6, Menus Rev. B

6.2 Setup Menu

Figure 6.2a Setup Menu

Menu Item Function

Microscope Opens the system configuration window. Allows selecting the microscope mode and allows selection of the type of scanner.

Laser Opens the laser alignment window

Tapping Opens the cantilever tuning window

Stage motors Opens the stage motors window and allows moving the head assembly

Closed Loop Opens the closed loop window where x and y linearizer are turned on and off and gains are specified

Engage Opens the engage window and allows engaging, withdrawing and selection of engage mode parameters

Recalibration Enables the scanner calibration functions for xy or z.

Ch. 6 - MenusReal Time Control Menu


6.3 Real Time Control Menu

Figure 6.3a Realtime Control Menu

Menu Item Function

Scan Control Opens the scanning window. Specifications include: the imag-ing channels, input scan parameters, activate LiftMode, activate bias voltages for tip bias and sample bias, overscanning, closed loop on/of, high/low gain HV and X/Y axis moves and control scanning conditions.

Point Spectroscopy

Used to measure force-distance curves and IV curves.

Signal Tracing

A more generic version of the point spectroscopy capability which allows selection of any available driving signal while monitoring any available channel.

Probe positioning

Allows recording specific coordinates and moving the probe to the specified coordinates

Multimeter Opens a digital multimeter and to monitor specified channels

Oscilloscope Opens an oscilloscope window

Ch. 6 - MenusTools Menu


6.4 Tools Menu

Figure 6.4a Tools Menu

Menu Item Function

Image Analysis

Opens the SPMLab analysis software

NanoPlot Opens NanoPlot Software

Ch. 6 - MenusWindow Menu


6.5 Window Menu

Figure 6.5a Window Menu

Menu Item Function

Cascade Displays window stacked on each other (see menu icon)

Tile Horizontally

Displays windows with priority given to displaying width (see menu icon)

Tile Vertically

Displays windows with priority to height (see menu icon)

Ch. 6 - MenusToolbuttons


6.5.1 Control Pane Info Menu

Figure 6.5b Info Menu

6.6 Toolbuttons

Figure 6.6a Toolbuttons

Menu Item Function

About… Provides information on the software release

System info Provides system status information:Microscope mode, scanner type and the number of activated channels. It also gives a DSP status and DSP error status

Ch. 6 - MenusOther Controls


6.7 Other Controls

Figure 6.7a Main Window Controls

Laser on/off

Z-position (if feedback

Feedback on/off

Gains

Feedback signal

Piezo position indicator

Engage indicator

Bias voltage controls

Optical microscope light

Optical camera zoom

{

is off)

Slide control

Slide Control

Microscope light on/off

Ch. 6 - MenusOther Controls


Right clicking on a section of the Main Window controls will open a window which permits selection of which control sections will be displayed or hidden.

Figure 6.7b Display/Hide Control Sections

The incremental values of the scroll controls may be modified by double clicking in the

parameter window.

Ch. 7 - Contact Mode ImagingOverview

Rev. B Innova User Manual - Ch. 7, Contact Imaging 93

Chapter 7 Contact Mode Imaging

7.1 Overview

This chapter assumes setup of Innova as described in Chapter 4. Further details and background information related to many of the procedures in this chapter are provided in other chapters.

The Innova system is comprised of the piezo scanner, Optics and the AFM detection system and the NanoDrive controller. The scanner houses the piezoelectric transducer. The piezo element physically moves the sample in the X, Y and Z direction. The force detection system consists of a laser which generates a spot of light that is reflected off of a microfabricated cantilever onto a mirror and finally into a photodetector. The position of the spot is determined by circuitry which generates a voltage from the difference between the photodiode segments. The circuit outputs a voltage ranging from +10V to -10V depending upon the position of the spot on the photodiodes.

The Innova system maintains the tip at the end of the cantilever in contact with the sample surface. The sample is scanned under the tip in X and Y. Features on the sample surface deflect the cantilever, which changes the position of the laser spot on the photodiodes. This position change is read by the feedback loop. The feedback loop moves the sample in Z to restore the spot to its original position.

WARNING: This instrument contains a laser. Use of controls or adjustments or performance of procedures other than those specified could result in hazardous laser light exposure.

7.1.1 Special Hardware Requirements:

Probes: DNP, NP or MLCT probes (General purpose Silicon Nitride cantilevers)

7.2 Startup

7.2.1 Cold start

If the system is already powered up and running skip to Warm Start: Section 7.2.2.

1. Turn the computer and monitors on. The computer on/off switch is located on the front panel of the computer unit. The computer monitor on/off button is located on the front of the monitor below the screen. Windows starts automatically and displays the desktop.

2. Turn on the NanoDrive. The on/off rocker switch is located on the lower left portion of the front panel of the controller.

Ch. 7 - Contact Mode ImagingStartup

94 Innova User Manual - Ch. 7, Contact Imaging Rev. B

3. From the Windows START button, select All PROGRAMS→VEECO→SPMLAB XP→ SPMLAB or double click the desktop icon for SPMLab.

4. SPMLab will launch and display a System Status window shown in Figure 7.2a.

Figure 7.2a System Status Window

5. Click OK to proceed.

7.2.2 Warm Start

1. If system has previously been powered on with SPMLab running, SPMLab will launch and display the system status window shown in Figure 7.2b.

Figure 7.2b Load DSP Code Again

2. Click OK to proceed.

3. SPMLab will launch in the same configuration as was last used. If this is not the desired configuration, modify the configuration as described below.

Ch. 7 - Contact Mode ImagingStartup


4. Select SETUP→MICROSCOPE, or click the Microscope toolbutton , to open the SPMLab System Configuration dialog box.

Figure 7.2c System Configuration

5. Configure the system software by making the following selections in the SPMLab System Configuration dialog box.

• MICROSCOPE: Innova

• Mode: Contact

• SELECT SCANNER: Select the menu item for the scanner that is currently installed (“Large” or “Small” Area).

6. Click to load the files corresponding to the configurations settings.

7. When the window asking “Turn HV on” appears, select Yes.

Figure 7.2d High Voltage Option Window

Ch. 7 - Contact Mode ImagingApproaching the Sample


7.3 Approaching the Sample

1. Before attempting to approach the sample, ensure that the sample is properly mounted and located as described in Loading a Sample: Section 4.6.

2. Before performing laser alignment, ensure that the chip carrier and probe cartridge are properly installed as described in Installing a Chip Carrier: Section 4.7.

3. A tip-to-sample approach brings the probe tip into contact with the sample so an image can be scanned.

7.3.1 Aligning Laser and Performing a Manual Approach

1. Enable the microscope optics and make necessary adjustments as described in Using the WinTV32: Section 4.9.

2. Turn on the laser by clicking on the laser toolbutton.

Figure 7.3a Laser On/Off Toolbutton

in = Onout = Off



3. Click on the Laser Alignment toolbutton to open the Laser Alignment window and check the alignment of the deflection sensor by looking at the laser position and intensity indicators on the probe head.

Figure 7.3b Laser Spot Centered

4. If realignment is necessary, follow the procedures in Aligning the Deflection Sensor: Section 4.10 and Deflection Sensor: Section 4.13.

5. Bring the cantilever into the optics field of view.

6. Focus on the sample.

CAUTION: Do not lower the probe head too far. If the probe tip hits the sample surface, both the probe tip and the sample will be damaged.

7. Open the Motor Stage window by clicking on the Motor Stage toolbutton and use the motor stage buttons to lower the probe until the cantilever begins to come into focus in the optical view. At this point, the cantilever will be close to, but not touching, the sample surface. To avoid damage to the tip (a “crash”), use “Slow” when the tip is near the sample.

Figure 7.3c Motor Stage Control Window



8. Choose a setpoint for the deflection feedback. The setpoint must be a larger positive value than the force deflection. If the laser has been aligned in the center, corresponding to a force deflection of approx. zero, a setpoint of +2.0 V may be appropriate. See Figure 7.3d.

9. Perform Auto engage as described in the following section

7.3.2 Engaging

CAUTION: Once the tip and sample are in contact, raise the probe head before turning off the power to the probe head. When the system is engaged, the Scan window (see Figure 7.3d) will appear.

A successful engage process will bring the probe into contact with the sample surface.

1. Ensure the auto engage mode is activated and click the Engage toolbutton .

2. During the engage process, the Z position bar (which represents Z piezo movement) will be “sewing” and the cantilever icon will indicate “Engaging”.

3. Use the default P, I and D gains in the feedback control window (see Figure 7.3d) these values may be optimized at a later time as described in Adjusting Feedback Parameters: Section 7.5.3.



4. The engage process is completed when the feedback signal bar shows the setpoint value and the Z position piezo bar is near mid range. The cantilever icon will indicate “Engaged” and the scanning window will be open.

Figure 7.3d Engage Completed

CAUTION: Improperly set Size and Gain parameters could result in damage to the tip or sample.

5. Ensure the Gain parameters are set to their default values.

Ch. 7 - Contact Mode ImagingTaking a Contact Mode Image


7.4 Taking a Contact Mode Image

1. Click anywhere on the Scan window to bring it to the top.

2. Check that the proper channels are selected and click OK.

Figure 7.4a Channels Selected in Acquire Panel

3. Review the Area scan parameters (i.e., Scan range, Scan rate, etc.). Scan rates of 1-2 Hz are typical.

4. Click the start button.

5. Activate the Profile option. Select the channel for display.

Figure 7.4b Scanning Window Profile Option

Ch. 7 - Contact Mode ImagingTaking a Contact Mode Image


6. Move the scan window to the second monitor.

7. Click Windows in the menu bar and select Tile Horizontally. The images from the selected channels will be displayed in the main window.

Figure 7.4c Selected Channels in Main Window

8. Select the proper realtime processing option to remove, for example, “tilt”, as desired.

9. To cancel the scan before it is finished, check the start button again.

Select desired option(s)

Ch. 7 - Contact Mode ImagingTaking Better Images


7.5 Taking Better Images

7.5.1 Before Beginning

This tutorial explains how to optimize the scan and feedback parameters to get the best image.

Before following the steps in this chapter, perform an auto approach and take an image. Scan parameters can then be adjusted. The Feedback controls are located on the left side of the SPMLab main window and Scan controls are located in the scanning window.

7.5.2 Setting Scan Parameters

SCAN RANGE

1. Position the cursor over the number in the SCAN RANGE (μm) textbox, and double-click to highlight that number. Alternatively, click and drag the cursor to select the number.

2. Type in a new scan size in microns, and then press the [Enter] key. Alternatively, use the scrollbox arrows to scroll through a range of values. It is unnecessary to type “μm” for the units.

3. A new scan with this scan size will start automatically.

4. Try a smaller scan with a scan width approximately half as wide.

The scan image should change. By choosing successively smaller scans, it is possible to zoom in on the region of interest.

SCAN RATE

1. Position the cursor over the number in the Rate textbox and double-click to highlight the old text. Alternatively, click and drag the cursor to select the number.

2. Type in a new scan rate in Hertz (= scan lines per second), and then press the [Enter] key.

3. A new scan will start automatically.

The scan rate can be adjusted while an image is being acquired. Image quality can be monitored as the scan rate is adjusted. When the optimum scan rate is determined, take a new image using that scan rate.



LEVELING

A tilted signal trace on the profile display indicates that the sample is tilted. The following steps describe how to adjust for this tilt.

1. Select the image window containing the image to be leveled.

2. Click the scroll box and select the leveling type

3. The available leveling types are:

• None

• 1DAC = zeroth order, line by line fit

• 1D line fit = first order, line by line fit

• 2DAC = zeroth order, plane fit

• 2D plane fit = 1st order, plane fit

7.5.3 Adjusting Feedback Parameters

The purpose of adjusting the feedback parameters is to obtain stable imaging conditions. These parameters are described in greater detail in other chapters.

OPTIMIZING THE PROPORTIONAL, INTEGRAL AND DERIVATIVE GAIN

CAUTION: Severe oscillation may damage the probe and/or sample.

1. Begin with the default gain value.

2. Click proportional gain in the feedback window. The gain value will increase in 0.001 increments.

3. Click the scroll up tool until the system begins to oscillate.

4. Stop when oscillations begin appearing superimposed on the signal trace of the grating in the Oscilloscope Display.

5. Lower the gain incrementally by clicking the scroll down tool until the oscillations disappear. The goal is to be close to, but not beyond, the point at which oscillation appears. The proportional gain value is now optimized.

6. Repeat this procedure for integral gain. Usually integral gain changes produce the greatest effect.

7. Derivative gain setting may be experimented with to attempt to improve the trace.



SETPOINT

1. Position the cursor over the number in the setpoint scrollbox, and double-click to highlight the old value. Alternatively, click and drag the cursor to select the number.

2. Type in a new setpoint value, and then press the [Enter] key. Alternatively, use the scrollbox arrows to scroll through the range of setpoint values.

3. Click the start scan toolbutton to begin a new scan.

4. Adjust the setpoint while a scanning to see the immediate effect.

OPTIMIZING THE SETPOINT

1. Ensure that both the forward and reverse scan checkboxes are checked for the height signal in the channel selection tab of the scanning window.

2. To adjust the setpoint, type a new value in the setpoint scrollbox, and then press the [Enter] key.

Alternatively, use the scrollbox arrows to scroll through the range of setpoint values.

The setpoint can be changed while scanning is progress.

3. Compare the forward and reverse traces on the line profile display.

When the setpoint is optimized, the two traces will be nearly identical.

SELECTING THE NUMBER OF DATA POINTS

1. Activate the scan window and ensure the area scan is activated by clicking on the scan area button.

2. Use the resolution scrollbox to select the image pixel size.

Figure 7.5a Scanning Window Controls

Scan Area Button

Resolution ScrollboxCapture tool

Continuous Capture

Continuous Scan

Scan

Ch. 7 - Contact Mode ImagingLFM Imaging


3. Experiment by taking images using several different numbers of data points.

CAPTURING IMAGES

1. All images are saved to the computer hard drive as long as the capture tool (see Figure 7.5a) is enabled.

2. To perform continuous scans, enable the Continuous Scan toolbutton (Figure 7.5a).

3. To save all images continuously, enable the Capture Tool and Continuous Capture tool (Figure 7.5a).

4. Alternatively, a single frame scan can be saved after it is complete by the menu sequence: File > Save.

7.6 LFM Imaging

Lateral Force Microscopy (LFM) is an extension of Contact mode that can provide additional information about the sample surface by measuring the torsional deformation of the cantilever (represented by the LFM signal) as well as the vertical bending (represented by the deflection signal).

After completing performing Contact mode imaging, LFM images may be taken without interrupting the imaging session. Since the LFM signal is always available during Contact mode operation, monitor it by the following:

• Open Scan window

• Select Channels tab

• Select Lateral signal - Forward and/or Backward

Figure 7.6a Lateral Signal - Backward Selected



WARNING: Observe all Warning and Caution statements in Chapters 1-4 when using the Innova system.

This section assumes familiarity with taking Contact mode images with Innova and that the system is installed and set up.

7.6.1 Taking an LFM Image

A “good” LFM image is relatively easy to identify when imaging the 10 µm calibration grating. Also, image quality is not as sensitive to scan parameter adjustment as it might be for other samples. While it might seem that a grating would only show contrast due to changes in height, there are sometimes contaminants on the grating surface that are “sticky.” These contaminants produce contrast in LFM images due to changes in frictional coefficients.

When taking an LFM image, it is often useful to view both height and LFM data collected from both the forward and reverse sweeps of the scanner in order to distinguish between frictional and topographic information.

Setting Up the System

1. Place a calibration grating on the scanner sample mount.

2. Install the probe head.

3. Make the following selections in the Microscope database configuration dialog box:

4. Select SETUP→MICROSCOPE, or click the Microscope toolbutton , to open the SPMLab System Configuration dialog box.

5. Configure the system software by making the following selections in the SPMLab System Configuration dialog box.

• MICROSCOPE: Innova

• MODE: Contact

• SELECT SCANNER: Select the file that has the scanner calibration values for the scanner that is currently installed.

6. Click to load the files corresponding to the configurations settings.Apply



7. When the window asking “Turn HV on” appears, select Yes.

Figure 7.6b High Voltage Control Window

8. Align the deflection sensor.

9. Perform an approach to bring the tip into feedback at the sample surface.

Selecting the LFM Signal

1. Open the Scan window and select channel height (forward and backward) and Lateral signal (forward and backward).

Figure 7.6c Channels Selected in Acquire Window

This selection of channels generates both left-to-right and right-to-left LFM and height data.



7.6.2 How LFM Works

An instrument producing LFM data is equipped with a cantilever detection scheme that measures both vertical and lateral bending of the cantilever. In Contact mode, vertical bending of the cantilever is measured, representing changes in sample height. By measuring lateral bending (or twisting) of the cantilever as well, LFM data is used to monitor motions arising from forces on the cantilever that are parallel to the plane of the sample surface. Such forces can arise from changes in the frictional coefficient of a region on the sample surface or from onsets of changes in height. LFM is therefore useful for measuring lack of homogeneity in surface materials and producing images with enhanced edges of topographic features.

The LFM Signal

As with Contact mode, LFM uses a beam-bounce detection scheme, employing a QuadPhotoDetector (QPD) to measure the bending of the cantilever. In LFM, the QPD is used to detect both lateral and vertical deflection of the cantilever. Figure 7.6d illustrates a QPD.

Figure 7.6d A QuadPhotoDetector (QPD)

LFM is able to collect both topographic (Contact mode) and frictional (LFM) information during a single scan. The topographic information is represented by vertical deflection of the cantilever, which produces a difference upper and lower quadrants of the QPD. This signal difference is termed the “A-B” or deflection signal, referring to the upper and lower halves of the QPD in Contact mode, and is represented by:

Deflection signal = (A+C) – (B+D)

Topographic information is also represented by the height signal, which is a function of the A-B signal.

Frictional information (the LFM signal) is represented by torsional deflection of the cantilever, which is measured as the difference between the left and right quadrants of the QPD:

LFM signal = (A+B) – (C+D)

By acquiring both the height and LFM signals, an instrument operating in LFM can produce height andLFM images simultaneously.



LFM Tip-Sample Interaction

This section describes how LFM images correlate with changes in frictional coefficients and height on a sample surface. This description will helps to compare and interpret the information in LFM and Contact mode images.

Figure 7.6e illustrates how a cantilever responds to changes in height, and how that response correlates with the resulting LFM and height data. Vertical motion of the cantilever is depicted as a change in the vertical position of the cantilever. Lateral motion of the cantilever is depicted as a change in the angle of the tip with respect to the horizontal.

Figure 7.6e shows that a change in sample height creates both vertical and lateral changes in cantilever position. The lateral component is not reflected in the height image, which is based on the feedback loop driven by the vertical bending of the cantilever. Figure 7.6eb shows the topography signal trace that would result from the height of Figure 7.6ea.

Figure 7.6e Cantilever Response to Change In Height with Corresponding Topography and LFM Signal Traces.

Figure 7.6ec shows the LFM signal trace that would result from the height of Figure 7.6ea. As the figure shows, the LFM data reflects only the lateral components of bending (e.g., bending to the right at the rise in height produces a positive signal and bending to the left at the drop in height produces a negative signal).

Figure 7.6f illustrates how a cantilever responds to changes in frictional coefficients and how that response correlates with the resulting LFM and height data.

Figure 7.6fa shows a change in frictional coefficient that causes the cantilever to bend to the right for a scan that is taken from left to right. If the scan is taken from right to left, as illustrated in Figure 7.6fb, the cantilever bends to the left as it passes over the change in frictional coefficient. A change in height causes the same type of cantilever bending illustrated in Figure 7.6e.

Figure 7.6fc shows a topography signal trace resulting from the surface of Figure 7.6fa: the data only reflect the change in sample height. Figure 7.6fd shows the LFM signal trace that would result from a scan taken from left to right. Figure 7.6fe shows the LFM signal trace that would result from a scan taken from right to left. The sign of the LFM signal flips for the change in friction, but not



for the change in height. Changes in height appear on an LFM image as adjacent dark/bright regions. By identifying these adjacent dark/bright regions, and by viewing data from two scan directions, a user looking at an LFM image can distinguish between contrast changes due to changes in frictional coefficient and those due to changes in height. Image subtraction, available in the SPMLab analysis software, can be used to reduce topographic effects in LFM images.

Figure 7.6f Cantilever Response to Change in Frictional Coefficient and Height, and Corresponding Contact Mode (AFM) and LFM Signal Traces.

Side-by-side height and LFM data therefore provide complementary information. By monitoring the LFM signal, the contribution of lateral cantilever bending to a Contact mode image can be inferred. Conversely, having the Contact mode information available confirms that contrast changes on an LFM image that are due to changes in height, rather than frictional coefficient.

When scanning, the fast scan direction to be selected to be x or y (horizontal or vertical). As an image is being taken, the scanner rasters back and forth over each scan line in the fast scan direction, and then advances to the next line in the slow scan direction. To maximize LFM signals, choose the scan angle so that the fast scan direction is perpendicular to the cantilever axis (scan angle 0 or 180 degrees. Once a fast scan direction has been selected, forward or reverse sweep data can be selected for viewing. For example, if fast scanning is x scan, data collected from the



right-to-left sweep of the scanner, or from the left-to-right sweep of the scanner, or from both sweep directions may be selected for viewing.

Figure 7.6g Fast Scan for Optimum LFM Data

Fast Scan Direction



Ch. 8 - TappingMode ImagingOverview

Rev. B Innova User Manual - Ch. 8, Tapping AFM 113

Chapter 8 TappingMode Imaging

8.1 Overview

This chapter describes an example of a TappingMode imaging session. Briefly, TappingMode imaging is performed by monitoring the oscillation amplitude and phase of an oscillating cantilever probe. The probe to sample distance is set so that the probe tip lightly contacts (“taps”) the sample surface during the cantilever oscillation. As the probe interacts with the surface of a sample, the oscillation amplitude or phase relation to the exciting signal changes in response to the interaction. The interaction provides the basis for producing an image of the sample.Throughout this chapter, many of the settings used are default values of the program. Experienced users may wish to override the defaults based on their knowledge of the sample and imaging requirements. In general, the default settings are acceptable starting points for most applications.

One advantage of TappingMode AFM is reduction of frictional forces which exert torque on the cantilever. Unlike traditional Contact mode which maintains a constant cantilever deflection, the TappingMode feedback loop keeps the cantilever oscillating at a constant amplitude. The tip on the cantilever is oscillated at a frequency near or at the cantilever resonance. A laser beam is reflected off a microfabricated cantilever, onto a mirror, then onto a photodiode. As the cantilever vibrates, the laser spot oscillates across the photodiode and produces an AC voltage. The signal from the photodiode is rectified, then lowpass filtered into a DC voltage (measuring the RMS Amplitude). The RMS amplitude is proportional to the amount of cantilever motion.

The feedback system compares the RMS amplitude to the setpoint voltage. The two voltages are kept equal by controlling the amplitude of cantilever movement. The sample surface is in close proximity to the cantilever such that the tip touches the surface only at the lowest point of its oscillation. The RMS voltage is reduced to the setpoint voltage by the feedback loop moving the sample nearer to the tip. The sample reduces the cantilever movement until the desired RMS voltage is reached. The oscillation amplitude of the cantilever is held constant by the piezo moving the sample in Z as it is simultaneously translated in X and Y.

Engagement in TappingMode AFM requires that the setpoint voltage be smaller than the RMS voltage when the probe to sample distance is large (far from engaged). The tip to sample spacing is reduced until the RMS amplitude is at the setpoint.


Probes: TESP, RTESP (Silicon cantilevers) for general purpose imaging -- employed in this example. FESP for light tapping on soft samples LTESP for hard tapping on soft samples

Ch. 8 - TappingMode ImagingStartup

114 Innova User Manual - Ch. 8, Tapping AFM Rev. B

8.2 Startup

1. Set up with the appropriate probe and cartridge for TappingMode operation. Refer to Chapter 4.

2. With the system properly installed and turned on, launch SPMLab by double clicking the desktop icon and select Yes when asked to load the DSP code.

Figure 8.2a System Status Window

3. The System Configuration window will appear and show the previous configuration settings. To perform TappingMode imaging, select settings as shown in the figure. These settings provide a reasonable set of initial settings and may be changed later as desired. When the appropriate selections have been made, select Apply to proceed.

Figure 8.2b System Configuration

4. The Turn HV on panel will appear. Select Yes.

Figure 8.2c Turn HV (High Voltage) On

Ch. 8 - TappingMode ImagingCantilever Tuning - Manual Tuning Method


5. Laser alignment is described in Aligning the Deflection Sensor: Section 4.10 and Deflection Sensor: Section 4.13 in this manual. Ensure the alignment is proper before proceeding with this exercise.


Note: A explanation of most toolbuttons will appear when the mouse cursor is hovered over the button.

7. A representation of the laser spot will be displayed. The spot should be centered on the cross hairs using mechanical controls on the SPM.

Figure 8.2d Laser Spot Centered

8.3 Cantilever Tuning - Manual Tuning Method

Tuning consists of determining the proper frequency, amplitude and phase of the signal used to oscillate the cantilever. This section describes the manual tuning process. Cantilever tuning can also be accomplished automatically using the autotune function which is described in the following section (8.4).

1. Click on the Cantilever tuning dialog toolbutton to open the Cantilever Tuning window.



2. Set the Range setting to 0 - 600 kHz or select an appropriate range for the probe in use (the

resonance of TESP probes is near 300 kHz so 600kHz is appropriate) and click the

Start/Stop Frequency Sweep toolbutton.

Figure 8.3a Set-up and Start Scan



3. An initial plot of amplitude and phase vs. frequency will be generated.

Figure 8.3b Initial Plot of Response vs. Frequency

4. To expand the area of interest, select the Pan/Zoom option and click and drag a zoom box on the plot area.



Note: The zoom box must be drawn from “Northwest” (10 o’clock) to “Southeast” (4 o’clock) in order to zoom. If drawn in other directions, the result is an “unzoom” to the original plot.

Figure 8.3c Zoom Box Dragged on Plot



5. When the mouse button is released, the zoom box expands and the zoomed plot is shown.

Figure 8.3d Plot expanded to zoom box

6. Repeat dragging zoom boxes as required to obtain an expanded display of the amplitude and phase plots.

Figure 8.3e Zoom Again



7. Continue to zoom until the peak response is displayed over some width on the plot.

Figure 8.3f Peaks Exhibit Width

8. Click the Start/Stop Frequency Sweep toolbutton to regenerate the plot over the zoomed frequency range then select Set Frequency.

Figure 8.3g Select Frequency



9. Position the mouse cursor at the peak of the amplitude curve and click to select the peak frequency.

Figure 8.3h Select Amplitude Peak

10. Position the cursor at the peak so that a dotted vertical line is displayed and note where it crosses the phase curve (in this example, the vertical line crosses the phase plot at a phase value of approximately 1 volt).

Figure 8.3i Phase Value at Amplitude Peak



11. Adjust phase by clicking the Phase Autonulling toolbutton . The Phase scroll box will display the phase value (in degrees) where the phase signal is 0 volts (at the specified frequency).

Figure 8.3j Adjust Phase

Note: Phase adjustment is not required for basic tapping mode imaging because the feedback loop utilizes amplitude, not phase. Phase adjustment is, however, required to obtain the desired contrast in “Phase Imaging”, that is, when selecting the Phase as a channel to be recorded.

Phase Autonulling ToolbuttonPhase Scrollbox

Ch. 8 - TappingMode ImagingAutotune


12. The setpoint value is automatically calculated (60% of peak amplitude).

Figure 8.3k Setpoint Voltage Calculated

Note: Typical peak amplitudes should be 5-6V. This can be accomplished by either increasing/decreasing the drive amplitude and/or by either increasing/decreasing the input gain. The input gain represents a gain applied to the cantilever signal. Working at high input gain values (20 or greater) implies small amplitude oscillation of the cantilever.

8.4 Autotune

Autotune automates much of the cantilever tuning process. It automatically selects the cantilever tune frequency based on the maximum response within a specified frequency sweep range. If selected, autotune also adjusts drive amplitude and phase. The results of autotune, based on user specifications usually produces good results and is easier than the manual tune process previously described (see 8.3). The procedure for autotuning is:

Note: Throughout this procedure for autotune, accepting the default values in any window will generally provide good results. The example screens are for illustrative purposes.



1. Select the frequency range for the autotune sweep, refer to Figure 8.4a (the maximum response will be found within this range).

Figure 8.4a Drop Down Selection of Frequency Range



2. Drive amplitude for cantilever oscillation can be set in either of two ways. The Drive Amplitude value may be scrolled up/down as shown in Figure 8.4b

Figure 8.4b Drive Amplitude Selection

3. Another way of setting the drive amplitude is by enabling the Adjust Drive Amplitude check box and entering a value in the Target Tapping Signal input box as illustrated in



Figure 8.4c. When a value is entered for the Target Tapping Signal and autotune is performed, any value in the Drive Amplitude box will be overridden.

Figure 8.4c Autotune Drive Amplitude Setting

Ch. 8 - TappingMode ImagingEngage


4. Autotuning is performed by clicking the Scan toolbutton and will produce a display similar to that of Figure 8.4d.

Figure 8.4d Autotune Scan Performed

8.5 Engage

Engage is the process of moving the sample and tip closer to each other until a desired degree of interaction occurs. The Setpoint defines whether or not the SPM is engaged/operating in TappingMode. When the cantilever is oscillating freely, a characteristic ac voltage results. As the cantilever nears a sample and begins to interact with it, the oscillation amplitude (and the corresponding ac voltage) is reduced. In this illustrated example, the free oscillation corresponds to 5.75 volts and 3.5 volts defines the value at which the tip is “engaged” with the sample and which feedback will attempt to maintain as the sample height changes. A setpoint of greater than 5.75 volts would imply that the tip is held far enough away from the sample that there is no interaction (therefore no imaging). A setpoint of 0 volts would occur when the cantilever is not oscillating because it is in solid contact with the sample. Lower setpoints imply higher contact forces between tip and sample with consequently higher probability of damage to the tip or sample. The suggested setpoint value of 60-70% of the free amplitude is a rough starting value and depends upon the sample.



1. Click the Engage control dialog toolbutton

Figure 8.5a Engage Control Dialog Toolbutton

2. The Engage window opens. Use Setpoint = 3.5

Figure 8.5b Engage Window



3. Click on the Engage tip: auto toolbutton

Figure 8.5c The Engage Window and Engage Toolbutton

4. During the engage process, the scanning and channel windows appear automatically

Figure 8.5d Scanning and Channel Windows

Ch. 8 - TappingMode ImagingScanning Windows


8.6 Scanning Windows

1. The channel windows display images based on different criteria and many channels are available. The available channels can be viewed by opening the Channel window.

Figure 8.6a Menu Selection to Open Acquire Window

2. The desired display channels can be selected in the Acquire window. The figure shows the default selections and they will be used in this example

Figure 8.6b Acquire Window



3. For ease in viewing, drag the Scanning window onto the second monitor screen.

Figure 8.6c Scanning Window on Second Monitor

4. Again, for viewing ease, select Window - Tile Horizontal (or Tile Vertical)

Figure 8.6d Menu to “Tile” Windows



5. Tiled windows permit all window to be viewed simultaneously.

Figure 8.6e Windows “Tiled”



6. In the Scanning window, click on the Start/Stop Scanning toolbutton.

Figure 8.6f Begin Scan

7. Select Profile and the current line being scanned will appear in the display.

8. Figure Figure 8.6f shows the height channel selected. Use the scroll window to select the desired channel for display.

9. Scanning will begin and images will appear in the channel windows. Beside each channel window a drop down window allows leveling to be selected. The figure shows one of the

Start/StopScanning

Profile selected

Height selected



drop down menus and 1D Line Fit leveling specified, which is a common choice, especially for height data.

Figure 8.6g Initial Scan and Set Leveling

Figure 8.6h Scans Shown with Histograms on Leveled Images

10. Use either the image data or the profile view in the scanning window to optimize scan and feedback parameters.

Ch. 9 - STM ImagingOverview

Rev. B Innova User Manual - Ch. 9, STM Imaging 135

Chapter 9 STM Imaging

9.1 Overview

This chapter describes STM imaging and includes information on STM tips used to take STM images. The instructions in this chapter assume familiarity with setting up the system and taking an image.

WARNING: Follow all Warning and Caution statements in User’s Guide when using the Innova system.

9.1.1 Special Hardware Requirements• Probes: CLST-PTBO or 20 mil or 0.5 mm tungsten or PtIr wire

• STM Cartridge: see Figure 9.2c

• Wire cutter (for cutting probe wire)

• 1/16” hex allen wrench

9.2 Preparing and Loading STM Tips

STM tips can be prepared using several different methods. This section describes the commonly used method of cutting a wire. A new STM tip must be prepared when first setting up for STM and also whenever the tip being used becomes damaged or oxidized.

STM imaging of a surface with high aspect ratio features (sharp or steep) requires etched tips, which have a much higher aspect ratio than tips made using wire cutters. With a relatively blunt cut wire tip, a tunneling current may occur between the side of the tip and the side of a surface feature, resulting in tip imaging effects in the STM image.

For STM imaging of an atomically flat surface—e.g., the surface of graphite—blunt cut wire tips may be more stable over time than etched tips and result in better STM images. However, blunt tips can also cause multiple tip imaging effects.

Ch. 9 - STM ImagingPreparing and Loading STM Tips

136 Innova User Manual - Ch. 9, STM Imaging Rev. B

9.2.1 Using Wire Cutters to Make STM Tips

Reasonably good tips can be produced by cutting tungsten or PtIr wire at a 45° angle with a pair of sharp wire cutters. The recommended wire diameter to use is 0.020" (20 mil wire or 0.5 mm wire).

The following items are required:

• 20 mil or 0.5 mm tungsten or PtIr wire

• a strong pair of wire cutters (appropriate for the type/gage of wire)

• a pair of needle-nose pliers

To make a tip by cutting wire:

1. Cut off a piece of wire between 1 and 1.5" long using a strong pair of wire cutters.

2. Grip one end of the wire tightly with a pair of needle-nose pliers.

3. Orient the wire cutters at a 45° angle relative to the wire, as shown in Figure 9.2a.

WARNING: STM tips are very sharp. Be careful when handling an STM cartridge with a tip loaded. Avoid leaving the STM cartridge on a table or other work surface with the exposed tip pointing up. Store the STM cartridge and tip in a container with a lid.

Cut the wire by using the wire cutters to pull and twist the end of the wire while snipping.

Figure 9.2a Holding Wire Cutters at a 45° Angle to Cut an STM Tip.



The resulting tip may not appear as sharp as it is. Tungsten STM tips oxidize fairly quickly and should be discarded after 1 to 2 days. Platinum iridium STM tips, on the other hand, do not readily oxidize and may be kept and used for a much longer time before degradation affects image quality.

The overall shape of tips made using wire cutters is not well-defined. STM images taken using these relatively blunt tips can show multiple tip imaging effects. Sharper, higher aspect ratio tungsten tips can be made using a tip etcher.

9.2.2 Using the STM Cartridge

STM imaging requires a specially designed STM cartridge, which contains a small hole for inserting an STM tip, as shown in Figure 9.2c and Figure 9.2d.

Figure 9.2b Side View of STM Cartridge with Tip Inserted.

Figure 9.2c STM Cartridge Photos and Schematic

STM tip

0.020" tungsten tipinserted into cartridge

set screw fortightening tip

Front Back



On the top side of the cartridge, a round metal contact pad delivers the tunneling current signal to the control electronics.

CAUTION: Keep the area around the metal contact pad clean.

The tip is tilted relative to the sample instead of pointing straight down. The tilt allows seeing the tip using the on-axis optical view.

The STM cartridge is installed in the probe head in the same way as the AFM cartridge, with the tip pointing down. The instructions below explain how to insert STM tips into the STM cartridge.

WARNING: STM tips are very sharp. Be careful when handling an STM cartridge with a tip loaded. Avoid leaving the STM cartridge on a table or other work surface with the exposed tip pointing up. Store the STM cartridge and tip in a container with a lid.

Use a tip that has been made using wire cutters or an etched tip. Insert the back end of the tip first.

Note: It is not necessary to be able to see the tip using the on-axis optical view. However, to see the tip in the on-axis view, have the sharp end of the tip extend from the STM cartridge approx. as far as the AFM cantilever chip on the AFM cartridge. If the tip is too long or too short, locating the tip using the on-axis optical view may be difficult.

9.2.3 To Insert a Tip Into the STM Cartridge:

1. Use a 1/16” hex allen wrench to loosen the set screw on the top side of the STM cartridge.

2. Grip the STM tip near its middle using a pair of needle-nose pliers.

3. Feed the back end of the tip through the hole in the underside of the cartridge, as shown in Figure 9.2d below. The underside of the cartridge is the side with the three embedded silver balls.

4. Keep feeding the tip through the hole until only approximately 3 mm of the sharp end shows. Keep the wire as straight as possible when feeding it through the hole. Quite often, the back end of a tungsten tip splinters and becomes difficult to fit through the hole. If this happens, trim the end with wire cutters to remove the splinter.



5. Check that the tip length is about right by comparing the STM cartridge with an AFM cartridge that has a cantilever chip loaded. The STM tip should extend out about as far as the AFM cantilever chip does on the AFM cartridge. It is usually easier to see the tip in the on-axis optical view if the vertical distance between the tip and the underside of the cartridge is between 2 and 3 mm.

Figure 9.2d Inserting a Tip Into the STM Cartridge.

6. Tighten the set screw on the top side of the STM cartridge using an allen wrench. The set screw is a 1/16" allen head.

7. Cut the back end of the tip with wire cutters after the tip is inserted and the set screw is tightened. The back end of the tip should not extend more than about 5 mm. Otherwise, the back end of the wire may scratch the objective lenses of the optical view.

CAUTION: Be careful to cut the back end of the wire short enough to avoid scratching the objective lens.

9.2.4 To Store an STM Cartridge with a Tip Loaded:

1. Place the cartridge in a container with a lid with the sharp tip pointing up.

2. Close the lid of the container.

9.2.5 To Remove a Tip from an STM Cartridge:

1. Loosen the set screw on the cartridge.

2. Grip either end of the tip with needle-nose pliers, and pull the wire out of the hole.

Ch. 9 - STM ImagingTaking an STM Image


9.3 Taking an STM Image

STM mode is often used for taking images with atomic resolution, however this type of imaging can be difficult for instruments operating in air, as an STM is highly sensitive to surface contaminants and water layers.

STM can be used to image metals as well as semiconductors without thick insulating oxide layers. For example, STM images can be taken of gold, graphite, and semiconducting oxides. STM cannot be used to look at insulating samples (e.g., Al2O3) because no tunneling current will flow between the tip and an insulating sample, and the tip will crash into the sample surface during engage.

Two examples of samples that can be used to demonstrate the capabilities of an STM operating in air are a gold-coated calibration grating and a highly oriented pyrolytic graphite (HOPG). The large, easily identifiable features of a calibration grating make it a good sample for a first image. Graphite is easily cleaved and is often used to demonstrate atomic resolution in air. Both samples provide a reflective surface that make it easier to perform a manual approach.

9.3.1 Startup

1. Install a small area scanner as described in Chapter 4. STM studies usually are concerned with atomic resolution. Although the large area scanner can also achieve atomic resolution, the small area scanner is recommended.

2. Click on the Microscope Set-up tool and select Scanners to insure that the Small area scanner is specified.

Figure 9.3a Select Small Area Scanner



3. Select Scanning Window and inspect Conditions settings to insure that HV gains are set appropriately. “High” is recommended for the Small area scanner; “Low” is strongly recommended for the large area scanner.

Figure 9.3b HV Gains Set Low

4. Load an HOPG (graphite) sample.

5. Ensure that the closed loop controls are off. (Not applicable for the small area scanner).

Figure 9.3c Closed Loop Off



6. Use the following scan parameters:

• Setpoint: 1 nA (or more if required to bring the sample into feedback)

• Bias: Sample, 100 mV

• Scan Rate: 12-25 Hz

• Scan Size: 4.0 to 8.0 nm

• Gains: Low values, e.g., 0.1

9.3.2 Troubleshooting

Check the electrical resistance of the path between the STM tip and the probe head using a multimeter on the Ohms setting.

1. Place one probe of the multimeter on the right brass screw of the two brass screws on the probe head which are positioned directly above the probe cartridge, which connects to the metal contact pad of the STM cartridge.

2. Place the other probe of the multimeter on the metal cylinder of the STM cartridge that holds the STM tip wire.

The resistance between the probe head and the tip should be small for STM operation, typically ~0.2 Ω.

If the STM cartridge is too loose or too tight, the conducting path may be disrupted. Try adjusting the position of the probe cartridge to establish good contact. If this does not help, call Veeco Customer Support for help in diagnosing the problem.



9.3.3 Preparing for Engage

Figure 9.3d shows settings preparatory to performing auto engage.

• Refer to “Use the following scan parameters:” on page 142.

• Setpoint is 1.0000 nA

• Integral and Proportional Gains are set as shown.

Figure 9.3d Settings Prior to Engage

Other parameters, such as the number of pixels per scan line, are set to default values that need not be changed. The default number of pixels per scan line is 256.

The high scan rates and low gains employed here will cause significant contrast to appear in the error signal (current image). The limiting case of very high scan rates and low gains, where all the information is contained in the current image, is sometimes called “constant height mode”. The opposite limit of slower scan rates and higher gain, where the error signal is minimized and most information is in the height image, is called “Constant Current” mode. On flat samples, it is often easiest to begin in constant height mode and gradually adjust parameters toward settings for constant current mode, once the desired contrast begins to appear.

Before initiating an approach, move the tip as close to the sample as possible by eye. However, be careful that the tip does not touch the sample surface. The closer the tip is to the sample surface, the less time the approach will require.

If using the Innova on-axis optics, the focus of the tip will be used for approach. If using separate optics, it is easiest to perform a tip-to-sample approach using the oblique view.



To bring the tip close to the sample using the optical view. The following steps refer toFigure 9.3e:

Figure 9.3e Preparing for Engage

1. Click the Motor Stage window

2. Use the positioning controls on the head to find the cantilever tip in the optical view and then focus on it.

3. Adjust the coarse and fine focus knobs on Innova to focus on the sample surface.

4. Move the tip toward the sample using the z direction pad.

5. On the TV monitor, watch for the shadow of the tip on the sample surface as the probe engages the sample.

6. Watch the tip approach close to the sample while using the down arrow tool.

7. Stop the approach when the tip is within a few millimeters of the sample surface.

9.3.4 Engaging

If desired, open a multimeter window and set it to display AL3-STM signal. This display allows viewing the STM current signal in raw (volts) units.

Figure 9.3f Second (AL3-STM Signal) Multimeter Window



Note: It is important to select “Fine” in the engage dialog window because the STM current generally becomes immeasurably small within a few nm of the surface. For this reason, tip sewing is needed throughout the engage process.

Click the Engage tool to begin an auto approach. In STM mode, this initiates the following sequence of steps:

• The scanner extends, moving the sample toward the tip with feedback enabled.

• The system monitors the tunneling current, checking for the setpoint value as the scanner extends.

• If the setpoint value is obtained, then the engage process stops.

• If the setpoint value is not obtained with the scanner fully extended, then the system retracts the scanner and lowers the probe head one step (of the stepper motor) toward the sample.

The above steps are repeated until the tunneling current matches the setpoint value.

The engage sequence is a slow process. The reflection of the tip may flicker in the optical view with each step. The Current signal in the multimeter window display should approach the setpoint value, and then stop.

When the approach stops, the tip will be within 1 nm of the surface but will not actually be in contact. After a successful engage, the green Piezo bar should show that the scanner has stopped moving and is extended to about half of its full range.

Note: The tip should never touch the surface in STM mode. If the tip makes contact, both the tip and the sample will be damaged. Contact between the tip and the sample, referred to as a tip “crash,” is indicated by an increased current reading on the multimeter display. If the tip crashes, it must be changed before proceeding.

Note: Operating at low currents in ambient STM is inherently challenging. It is not uncommon for contamination to produce unstable feedback and/or false engages. Should a false engage occur, i.e., a spike in current causes the system to enter an engaged state, clicking the approach button again will restart the approach process.



When the engage has been successful, the display should appear similar to:

Figure 9.3g Engage Successful

The AL3-STM signal multimeter will show a non-zero voltage and the status tool will indicate the SPM to be engaged.

9.3.5 Starting a Scan and Optimizing STM Scan Parameters

The following steps describe how to take a constant-current mode STM image. This section describes how to optimize the current and bias parameters used for taking an STM scan. The optimal values of these parameters depend on a number of factors, including the sample, whether it is semiconducting, and what type of semiconductor it is. Optimizing these parameters is usually a trial-and-error process.

The setpoint parameter sets the tunneling current during an STM scan. The tunneling current is given in nanoamps (= 10-9 amps). The tunneling current between the tip and the sample in STM is analogous to the force interaction between the tip and the sample in AFM. With feedback enabled and the feedback setting optimized, the system operates to keep the tunneling current constant by raising or lowering the sample.



Since the tunneling current varies exponentially with tip-to-sample spacing, the setpoint current basically controls the tip-to-sample spacing during a scan. Raising the setpoint value brings the tip closer to the sample, while lowering the setpoint value moves the tip farther from the surface.

Ideally, the tip should never come into contact with the surface during an STM scan, as both the tip and the sample surface will be damaged; e.g., the tip can leave a small pinhole or dent in the surface if it is driven into the surface.

Typically, the setpoint is less than 5 nanoamps for STM.

The tip-to-sample bias during a scan is set using the sample bias and tip bias parameters. If the sample is biased negative relative to the tip, then the STM image will represent tunneling from filled electronic states on the sample surface. If the sample is biased positive relative to the tip, then the STM image will represent tunneling into empty electronic states on the sample surface. The tip and sample biases are given in volts.

The bias settings have an indirect effect on the tip-to-sample spacing. In constant-current mode with feedback optimized, the system attempts to maintain a constant tunneling current by varying the tip-to-sample spacing. If the tip-to-sample bias is increased, the tunneling current also increases. The system therefore pulls the sample away from the tip to maintain constant tunneling current.

Typically, the bias between the tip and the sample should be lower than about 2 V in air. If the bias is larger than about 2 V, the STM will not be operating in the tunneling regime. The optimal bias to use depends on whether the sample is conducting or semiconducting. With conducting samples, a lower bias setting may be used. With semiconducting samples, use higher bias settings, but less than 2 volts. A typical bias range for STM is from about 0.1 to 2 V.

Figure 9.3h shows typical settings for an STM scan using the small area scanner on HOPG.

Figure 9.3h Typical Scan Settings for Atomic Resolution Imaging Using STM or Contact Mode AFM

Ch. 9 - STM ImagingConsiderations While Taking an STM Image


Figure 9.3i STM Image Showing Atomic Resolution on HOPG. 4nm x 4nm Image Size, 100mV Bias, 1nA Current Setpoint.

9.4 Considerations While Taking an STM Image

9.4.1 Sample Characteristics

Ideally, for a relatively flat, featureless sample, each signal trace should look similar to the one before. If scanning a sample with closely spaced periodic features (for instance, a 1 µm gold grating), look for features with the same spacing in the signal trace.

9.4.2 Optimizing Image

A signal trace that jumps erratically or that is jagged indicates that the scan parameters are not optimized. For instance, a saw-tooth signal trace might be an indication that the tip is tapping the surface as the sample is scanned. To increase the tip-to-sample spacing, decrease the tunneling current by lowering the setpoint value. As usual, scans size, offsets and angle can be important in achieving the desired image content.

9.4.3 Increased Risk of Sample/Tip Damage

Since the STM tip is held rigidly in place on the STM cartridge, it is much easier to damage both the tip and sample surface during a scan if the tip makes contact. (The AFM tip, on the other hand, is mounted on a flexible cantilever.)

Ch. 10 - Single Point SpectroscopyOverview

Rev. B Innova User Manual - Ch. 10, Spectroscopy 149

Chapter 10 Single Point Spectroscopy

10.1 Overview

Spectroscopy is performed by ramping either tip/sample separation or bias voltages with the tip at a single XY location. This can serve to analyze mechanical or electrical properties of the sample at a single point. Different elements or compounds will produce different attraction/repulsion signatures. This chapter provides an illustrative spectroscopy analysis session using z-ramping (i.e., force distance curves). Settings for specific analyses may vary from the illustration and may require some experimentation to produce suitable results. The program default settings usually provide reasonably useful starting values.


Probes: Typically the same probe which is used to obtain an image of the sample so that the point spectroscopy site can be selected.

10.2 Startup

1. Double click the SPMLab icon to launch the program.

2. If NanoDrive is not turned on, the following message will appear.

Figure 10.2a Cold Start Message

3. After NanoDrive is turned on, click OK to proceed.

Ch. 10 - Single Point SpectroscopyStartup

150 Innova User Manual - Ch. 10, Spectroscopy Rev. B

4. The system configuration panel will appear. The panel will typically display the previous setting and should be changed to Contact mode and the Apply toolbutton clicked.

Figure 10.2b Select System Configuration

5. The Turn HV on window will appear. Click Yes.

Figure 10.2c Turn HV On

Ch. 10 - Single Point SpectroscopyStartup


6. Start WinTV32 by Start > All Programs > Hauppauge WinTV > WinTV32.

Figure 10.2d Turn on WinTV32

Ch. 10 - Single Point SpectroscopyAlign Laser


7. The WinTV32 window will open.

Figure 10.2e WinTV32 Window

10.3 Align Laser

1. Use the adjustments on the Innova head to align the laser as described below.

Figure 10.3a Adjustments on Innova Head

QPD Laser

Head Position

Head PositionLeft/Right

Front/Back

Positioning Positioning

Ch. 10 - Single Point SpectroscopyEngage


2. Align the laser by:

a. Use stage positioning controls to position the cantilever in the field of view.

b. Use laser positioning controls to place the laser spot on the end of the cantilever.

c. Use QPD controls to center the representation of the spot onto the crosshairs in the laser alignment window

Figure 10.3b Laser Spot on Cantilever and Centered on QPD

10.4 Engage

1. Use the focusing adjustment on Innova to focus onto the surface of the sample, then use the Motors Stage controls to lower the cantilever until it begins to come into focus.

Figure 10.4a Focus on Sample and Lower Cantilever to Near Focus

2. Open the Engage window by clicking the Engage Control toolbutton .

a

b

c

Ch. 10 - Single Point SpectroscopyPrepare to Ramp


3. Select Z Adjustment in the engage window and click on the Engage toolbutton

Figure 10.4b AutoEngage, Z Adjust Selected

4. During the engage process, the scanning and image windows appear automatically.

Figure 10.4c Engage Successful

10.5 Prepare to Ramp

1. Select the point mode tool and the scan area tab in the Scanning window in order to view the current probe position. If desired, image data can be dragged from one of the image display windows into the scanning window and the probe position can be changed interactively (by click-and-drag), so that the single point spectroscopy will be performed at the point of interest.

Engagetoolbutton

Ch. 10 - Single Point SpectroscopyPrepare to Ramp


2. Drag the Scanning window and reposition the WinTV window to suit personal preference. To display the image windows simultaneously, use Windows > Tile Horizontally.

Figure 10.5a Tile Screens Horizontally

3. Open the Point Spectroscopy window by clicking the Point Spectroscopy Control dialog toolbutton .

Figure 10.5b Point Spectroscopy Screen Opened

4. In the Point Spectroscopy window, specify the Z start and Z end values (maximum and minimum Z voltage range).

Ch. 10 - Single Point SpectroscopyRamp


Note: If values outside the permissible/possible range are entered for Z start and Z end, the program will correct the values to acceptable ones.

Figure 10.5c Specify Z Range

10.6 Ramp

1. Begin ramping by clicking the Start/Stop Scanning toolbutton .

Figure 10.6a Perform Line Scan

Ch. 10 - Single Point SpectroscopyRamp


2. To obtain the “standard” trace in the figure, select the Z Inverse option

Figure 10.6b Specify Z Inverse

Note: Refer to the support note for additional details.

3. The response of piezo positioning devices is inherently non-linear. The non-linear response can be characterized and compensated for in hardware and software. This scanner linearization feature is activated by enabling the Z piezo linearizer (= closed-loop Z mode).

Figure 10.6c Enable Z Piezo Linearizer if Desired

Ch. 10 - Single Point SpectroscopySample Session with Probe Positioning


4. Since the probe has usually been brought into feedback before ramping, the Z-position maintained during feedback is usually a useful reference point. The “relative Z-position” refers the Z-start and Z-end positioning to the feedback point instead of referring it to zero volts of the Z-DAC drive voltage

10.7 Sample Session with Probe Positioning

This sample session describes how to obtain force distance curves for multiple sites:

Note: Obtaining force distance curves at multiple sites follows procedures previously described in Probe Position Window: Section 5.11. The descriptions in this section are somewhat abbreviated versions of the earlier instructions.

1. Scan the area containing the site(s) of interest.

2. Drag the scanned image into Scanning window.

3. Open the Probe Positioning window and click on the scanned image in the Scanning window at the locations to measure force distance curves. As the locations are selected, the coordinates of the locations will appear in the Probe Positioning window.

Figure 10.7a Probe Positioning and Scanning Window

Location Coordinates

Selected locations



4. Open the Point Spectroscopy window and enable Merged to Probe Position.

Figure 10.7b Select Merged to Probe Position

5. Click Move probe in the Probe Positioning window to start or stop the force distance curve measurements at the specified sites.

Figure 10.7c Perform Force Distance Measurements and Save Results



6. When the force distance curves have been produced, save the data by clicking the Save toolbutton in the Probe Positioning window. This will open a typical windows to specify the file name and location for the saved data.

7. The saved data file is a text file (with the default file extension: “.pos”) which may be used for analysis.

8. Use the Table toolbutton to display the force curve data as a table. Clicking on a column heading selects a force curve for display when the probe positioning tool has been used to acquire a series of curves which results in a table with multiple columns.

Ch. 11 - MFM ImagingOverview

Rev. B Innova User Manual - Ch. 11, MFM Imaging 161

Chapter 11 MFM Imaging

11.1 Overview

MFM (Magnetic Force Microscopy) requires a separate accessory which is not included in the basic Innova system. This chapter provides a basic description of MFM. A detailed support note is included with the accessory.

MFM imaging utilizes the Interleave and LiftMode procedures. LiftMode is also used in EFM (see Chapter 12). In MFM, a tapping cantilever with a magnetized tip is scanned over the sample in TappingMode to obtain topographic information. Using LiftMode, the tip is then raised above the sample surface. Surface height from the initial scan is added to the lift height to maintain constant separation during the lifted scan. The influence of magnetic force is measured using the principle of force gradient detection. In the absence of magnetic forces, the cantilever has a resonant frequency f0. This frequency is shifted by an amount Δf proportional to vertical gradients in the magnetic forces on the tip. The shifts in resonant frequency tend to be very small, typically in the range 1-50Hz for cantilevers having a resonant frequency f0 ~100kHz. The shift in resonant frequency produces a change in both amplitude and phase (for a given drive frequency). These frequency shifts can be detected using: phase detection, which measures the cantilever’s phase of oscillation relative to the piezo drive and amplitude detection, which tracks variations in oscillation amplitude. Phase detection usually produces results that are superior to amplitude detection.

This chapter contains an illustrative example of program setup and imaging in MFM. It is assumed that the Innova system and MFM applications module are properly installed and powered up as described in the Innova user manual. Detailed information on probe preparation and installation is contained in the MFM support note which is included with the accessory.

11.2 Special Hardware Requirements

Probes: MESP Series probes (cobalt/chrome coated)

MFM Tool Kit INMF-3 which includes

• MFM Probe magnetizer

• non-magnetic sample holder

• MFM standard sample

• MESP probes

Ch. 11 - MFM ImagingStartup

162 Innova User Manual - Ch. 11, MFM Imaging Rev. B

11.3 Startup

1. Launch the SPMLab program by double clicking the program icon. The System Status window will appear.


2. Load the DSP code by clicking the Yes toolbutton and select the correct microscope configuration (Tapping).


Ch. 11 - MFM ImagingStartup


3. When the appropriate selections have been made, click Apply and the Turn HV on window will appear.


4. Turn on HV by clicking the Yes toolbutton.


Note: Some procedure details have been omitted and are described in the MFM support note.

6. The Laser Alignment display provides a representation of the laser spot location on the QPD (quad photo detector). Make adjustments on Innova as required to center the spot.

Figure 11.3d Laser Alignment

Ch. 11 - MFM ImagingCantilever Tuning


11.4 Cantilever Tuning

Cantilever tuning can be performed manually or using Autotune. Both procedures are described.

11.4.1 Manual Cantilever Tuning:

1. Open the Cantilever Tuning window by clicking on the Cantilever tuning dialog toolbutton

Figure 11.4a Cantilever Tuning

Cantilever Tuning



2. Generate a response plot by clicking the Start/Stop Frequency Sweep toolbutton.

Figure 11.4b Initial Response Plot

3. Select the Pan/Zoom option and drag a selection box over a frequency range around the lower peak response. (Typical resonance frequencies for MFM tips are in the 60-70kHz range.)

Note: Drag the box from a “NorthWest” to “SouthEast” (10 o’clock to 4 o’clock) direction to zoom, any other direction to revert to the original plot.

Figure 11.4c Pan/Zoom on Low Frequency Peak

Start/StopFrequencySweep

Pan/Zoom option



4. Continue to draw selection boxes until the peak exhibits some width and click on the Start/Stop Frequency Sweep toolbutton to produce a new scan within the range of interest.

5. Select the Set Frequency mode and move the cursor to the peak of the amplitude curve. This will display the value of the amplitude as well as the frequency indicated by the cursor. In this example, the amplitude is 6.695 volts at a frequency of 67.635 kHz.

Figure 11.4d Check Peak Amplitude Voltage and Frequency

Adjust the phase setting and re-scan as required until the phase voltage at the frequency for peak amplitude is approximately 0 volts. In this example, the phase was changed from 190 degrees (see figure Figure 11.4d) to 310 degrees.

Figure 11.4e Adjust Phase to Align 0 Volts at Peak Amplitude

Set Frequency

Adjust phase



11.4.2 Cantilever Tune with Autotune

As illustrated inFigure 11.5f

1. Select Autotune

2. Select an appropriate frequency Range (24-300 kHz for MESP probes).

3. Enable Use Current Frequency Range.

4. Enable Adjust Drive Amplitude.

Figure 11.4f Cantilever Tuning Window Settings for AutoTune

5. Click the Start/stop Scan toolbutton.

Start/stop scan

Ch. 11 - MFM ImagingEngage


6. When AutoTune is completed, peak frequency and phase will be optimized.

Figure 11.4g AutoTune Completed

11.5 Engage

1. Using the adjustments on Innova, adjust the focus so that the WinTV2000 image shows the sample surface to be in focus.

Note: Most surfaces being scanned in MFM are highly polished and it may be difficult to focus on the surface. Usually slight scratches, blemishes or contaminants exist to assist focusing.

2. Use the Motor stage controls to lower the probe until it begins to come into focus and select the engage toolbutton.

Figure 11.5a Focus on Sample Surface

Engage toolbutton



3. In the Engage window, set the engage mode to Auto, select Z center and click the engage toolbutton.

Figure 11.5b Engage

4. When engage is completed, the channel screens will appear and WinTV will show the sample surface in focus and the probe in sharper focus than before engage.

Figure 11.5c Engaged, Optics Focused

5. Click the stop/start button to begin a scan. Ensure that the scan and feedback settings result in satisfactory surface tracking.

6. Stop the scan and select Mode in the scanning window, select the Lift tab and enable lift mode. Choose a lift height (30-60 nm is typical depending upon the sample and scanning conditions). Click Ok to exit the dialog and activate the settings. The lifting occurs during the “backward” probe motion.

Auto

Engage

Z Center



Note: The “start height” parameter is usually not needed. It allows a higher initial lift height when needed to overcome adhesion on “sticky” samples.

Figure 11.5d Initial Scan to Check Setup

7. Click the menu selection Channels in the Scanning window and select appropriate channels for viewing MFM.

Note: The “backward” channels now carry the remark “(Liftmode)” Choose “Tapping > Phase > Backward (Liftmode)” to observe the MFM data.

Figure 11.5e Select Channels for MFM

LiftModeEnabled

Start/Stop Scan

SelectChannels



8. Tile channel windows and click Start/Stop Scan toolbutton to obtain MFM images.

Figure 11.5f Completed MFM Scan

9. To increase MFM contrast, reduce the lift height setting. A lift height setting too small will introduce strong artifacts from mechanical contact with the sample during the lift mode scan. These artifacts usually appear as pronounced spots or horizontal streaks in the backward (lift) phase line.



Ch. 12 - EFM ImagingOverview:

Rev. B Innova User Manual - Ch. 12 - EFM Imaging 173

Chapter 12 EFM Imaging

12.1 Overview:

EFM (Electric Force Microscopy) requires a separate accessory which is not included in the basic Innova system. This chapter provides a basic description of EFM. A detailed support note is included with the accessory.

EFM imaging utilizes the LiftMode procedure. LiftMode is included with the basic Innova system and is also used in MFM (see Chapter 11). In EFM, a tapping cantilever with a special conductive metal coated tip is first scanned over the sample in TappingMode to obtain topographic information. Using LiftMode, the tip is then raised above the sample surface while bias is being applied. Surface height from the initial scan is added to the lift height to maintain constant separation during the lifted scan. The influence of electric forces is measured. In the absence of electric forces, the cantilever has a resonant frequency f0. This frequency is shifted by an amount Δf proportional to electric forces on the tip. The shifts in resonant frequency tend to be very small, typically in the range 1-50Hz for cantilevers having a resonant frequency f0 ~100kHz. The shift in resonant frequency produces a change in both amplitude and phase (for a given drive frequency). These frequency shifts can be detected using: phase detection, which measures the cantilever’s phase of oscillation relative to the piezo drive and amplitude detection, which tracks variations in oscillation amplitude. Phase detection usually produces results that are superior to amplitude detection.

This chapter contains an illustrative example of program setup and imaging in EFM. It is assumed that the Innova system and the accessory is properly installed and powered up as described in the Innova user manual. Detailed information on probe preparation and installation is contained in the support note. A special probe carrier is required which permits the probe to be electrically biased through a connection (red colored socket) on the Innova stage.

Ch. 12 - EFM ImagingSpecial Hardware Requirements

174 Innova User Manual - Ch. 12 - EFM Imaging Rev. B


Electric Field Microscopy kit which includes:

• Unmounted chip carrier with lead (00-107-0142)

• Sample holder with external bias lead

• EFM sample

• SCM-PIT probes

Probes: SCM-PIT

Figure 12.2a Carrier Connection for EFM Plugs Into Black Socket at Front of Microscope Base

12.3 Startup

This section describes starting the program and making initial adjustments to Innova.

1. Launch the SPMLab program by double clicking the program icon. The System Status window will appear.


Carrier with Attached Cable

Ch. 12 - EFM ImagingStartup


2. Load the DSP code by clicking the Yes toolbutton and select the correct microscope configuration (Tapping).


3. When the appropriate selections have been made, click Apply and the Turn HV on window will appear.


4. Turn on HV by clicking the Yes toolbutton and on the Main window click on the toolbutton to Display Laser Alignment.

Figure 12.3d Display Laser Alignment

Ch. 12 - EFM ImagingCantilever Tuning


5. The Laser Alignment display provides a representation of the laser spot location on the QPD (quad photo detector). Make adjustments on Innova as required to center the spot.

Figure 12.3e Laser Alignment

12.4 Cantilever Tuning

1. Open the Cantilever Tuning window by clicking on the Cantilever tuning dialog toolbutton

Figure 12.4a Cantilever Tuning

Cantilever Tune



Generate a response plot by clicking the Start/Stop Frequency Sweep toolbutton.

Figure 12.4b Initial Response Plot

2. Select the Pan/Zoom option and drag a selection box over the lower peak response.

Start/StopFrequencySweep



Note: Drag the box from a “NorthWest” to “SouthEast” (10 o’clock to 4 o’clock) direction to zoom, any other direction to revert to the original plot.

Figure 12.4c Pan/Zoom on Low Frequency Peak

Pan/Zoom Option



3. Continue to draw selection boxes until the peak exhibits some width and click on the Start/Stop Frequency Sweep toolbutton to produce a new scan within the range of interest. The new scan will appear approximately as shown

Figure 12.4d Zoomed Response Plot



4. Select the Set Frequency mode and move the cursor to the peak of the amplitude curve. This will display the value of the amplitude as well as the frequency indicated by the cursor. In this example, the amplitude is 6.695 volts at a frequency of 67.635 kHz.

Figure 12.4e Check Peak Amplitude Voltage and Frequency

Set Frequency

Ch. 12 - EFM ImagingEngage


Adjust the phase setting and re-scan as required until the phase voltage at the frequency for peak amplitude is approximately 0 volts. In this example, the phase was changed from 190 degrees (see figure Figure 12.4e) to 310 degrees.

Figure 12.4f Adjust Phase to Align 0 Volts at Peak Amplitude

12.5 Engage

1. Using the adjustments on Innova, adjust the focus so that the WinTV2000 image shows the sample surface to be in focus.

Note: Most surfaces being scanned in EFM will be highly polished and it may be difficult to focus on the surface however, there will usually be slight scratches, blemishes or contaminants to assist focusing.

Adjust phase



2. Use the Motor stage controls to lower the probe until it begins to come into focus and select the engage toolbutton.

Figure 12.5a Focus on Sample Surface

3. In the Engage window, set the engage mode to Auto, select Z adjust and click the engage toolbutton.

Figure 12.5b Engage

Engage toolbutton

Auto

Engage

Z Center



4. The channel screens will appear automatically during the engage process and WinTV will show the sample surface in focus and the probe in sharper focus than before engage.

Figure 12.5c Engaged, TV Focused

5. Click the stop/start button to begin a scan. Ensure that the scan and feedback settings result in satisfactory surface tracking.

6. Stop the scan and select Mode in the scanning window, select the Lift tab and enable lift mode. Choose a lift height (30-60 nm is typical depending upon the sample and scanning conditions). Click Ok to exit the dialog and activate the settings. The lifting occurs during the “backward” probe motion.

7. The “start height” parameter is usually not needed. It allows a h.

Figure 12.5d Initial Scan to Check Setup

LiftMode,Enabled

Ch. 12 - EFM ImagingSet Tip Bias Voltage


8. Click the menu selection Channels in the Scanning window and select appropriate channels for viewing EFM. Select Tapping Phase - Backward (LiftMode) to obtain EFM data

Figure 12.5e Select Channels for EFM

9. Begin scanning and modify settings (range, rate, etc.) as required to produce desired images.

10. Tile channel windows and click Start/Stop Scan toolbutton to obtain EFM images

12.6 Set Tip Bias Voltage

EFM can be utilized to map conductive regions in composite samples. Applying a bias voltage between probe and sample will create electric fields and field gradients based on the distribution of the conductive component(s).

1. In the main panel on the left of the screen, enable the bias line and select tip or sample bias as desired.

2. In the Scan window, select Mode and select Double Bias

Figure 12.6a Select Double Bias



3. Click the check box for Enabled.

4. Enter the desired Bias Voltage(s). It may be desirable to select a non-zero bias as a second voltage (during the lift line) and a zero voltage as first voltage (during the main line), so that the bias voltage is being applied only when the probe is not touching the sample.



Ch. 13 - NanolithographyOverview:

Rev. B Innova User Manual - Ch. 13 - Nanolithography 187

Chapter 13 Nanolithography

13.1 Overview:

NanoPlot is an optional application which may be purchased separately and embedded within SPMLab to facilitate nanolithography applications. NanoPlot provides tools to produce line drawings and geometries and utilities to permit importing of graphics produced using other graphics generating software.

Nanolithography utilizes the precise positioning controls of the SPM to produce graphic images at the nanoscale. The images which can be produced range from simple geometries and line figures to false grey scale two dimensional graphics. Images may be produced by engraving the sample with the point of the SPM probe (scratching) or by applying an electrical potential to the probe and utilizing an electrochemical process (anodic oxidation) with the sample.


Probes: The probe type will depend upon the particular mode of lithography and the sample material. Commonly used probes include:

• SCM-PIT, MESP and DDESP-FM for anodic oxidation

• TESP for scratching

13.2 Startup

With SPMLab running,

1. From the menu bar, select: Tools > NanoPlot

Figure 13.2a Start NanoPlot Application

Ch. 13 - NanolithographyAdditional Instructions and Information

188 Innova User Manual - Ch. 13 - Nanolithography Rev. B

2. The NanoPlot window will open.

Figure 13.2b NanoPlot Application in SPMLab

13.3 Additional Instructions and Information

Detailed descriptions of the features of NanoPlot and using NanoPlot for nanolithography are contained in the separate user manual NanoPlot Software User Guide p/n 004-1002.

13.4 Nanolithography - A Sample Session

Nanolithography is typically accomplished in either of two modes: Scratching or anodic oxidation. Scratching, as the name implies, forces the probe tip into the sample to create an indentation by displacing the sample material. Scratching involves dragging the probe in Contact mode and is like drawing with a stick in the sand. Oxidation requires electrical biases to be applied to the probe tip or sample and the reaction in the fluid layer which is present under ambient conditions on the sample surface forms an oxidation layer on the sample. Anodic oxidation can be performed using either Contact or TappingMode AFM and is like creating an image by making a series of dots on paper with a pen. Oxidation may also be performed in Contact mode. In either scratching or oxidation modes, the tip/sample location is controlled using closed-loop piezo positioning so that very small and very precise lithography can be produced.

This section describes a nanolithography session using the oxidation mode. The sample session assumes familiarity with earlier sections of this manual and omits some details which have been discussed previously.

Ch. 13 - NanolithographyNanolithography - A Sample Session


1. Load a conductive tip with proper electrical contacts to permit applying an electrical bias.

Figure 13.4a Anodic Oxidation Chip Carrier and Stage Connection

2. Setup for TappingMode operation for 5 µm scan range + 1Hz scan rate + 256 pixel resolution.

3. Scan the sample.

4. Open NanoPlot.

5. Enable Bias Line and Tip.

Connection



6. Menu Tools > Setup in NanoPlot to enter SetPoint and Tip Bias.

Figure 13.4b Select or Set Circled Items

7. Use NanoPlot tools to draw or import graphics.

8. Click Etch.

9. Scan the sample to view results of nanolithography



Note: The procedure for scratching nanolithography parallels the preceding example except no bias is being applied and the “Z-Depth” function is used to decrease the probe to sample distance sufficiently so the probe is in permanent contact with the sample during the lithography move. When performing scratching lithography in contact mode, the setpoint function can be employed alternatively to obtain the required increase in force during the lithography move.

Figure 13.4c Nanolithography Sample w/Settings



Ch. 14 - CalibrationOverview

Rev. B Innova User Manual - Ch. 14, Calibration 193

Chapter 14 Calibration

14.1 Overview

This chapter describes how the scanner of the Innova instrument works and how to calibrate the scanner to maintain its optimal performance.

The scanner is a crucial component of the Innova system. The precision of the scanner motion is largely responsible for the quality and reliability of data. Understanding both the scanner's role in producing images as well as how to calibrate the scanner is therefore an important part of operating the instrument.

Typically, a Large Area scanner is provided with the Innova system. An optional small area scanner, which is useful for high resolution applications, is also available for use with Innova. This chapter focuses on the most common case of calibrating the large area scanner in high-gain, closed-loop mode. Analogous procedures apply for low gain mode, for open-loop operation and for the (open-loop) small area scanner.

Open loop scans may exhibit more nonlinearity and hysteresis.


PG Platinum coated calibration grating

STR-10 Surface height Reference Die

STS2 Surface height Standard

Ch. 14 - CalibrationTest the X and Y Detector:

194 Innova User Manual - Ch. 14, Calibration Rev. B

14.3 Test the X and Y Detector:

Upon starting the system, it is a good idea to check the status of the X and Y Linearizer signals to make sure they are behaving normally. This will be useful for the next step (XY Calibration) which depends upon the Linearization detectors working normally. To check the X-Linearizer signal, open the Signal Tracing window (Realtime Control > Signal Tracing). Select “DAC 0 X Channel” from the Driving Signal pull down menu, and check the Bi-Direction box below it. Then select the X Linearizer data channel checkbox to plot the signal. The expectation is that the scanner range will be approximately 100 microns and that this corresponds to voltage numbers larger than ±5V on the linearizer. The example here shows a typical symmetrical X signal trace, producing about ±8V on the linearizer. The same procedure can be used to evaluate the Y Linearizer. Just select DAC1 Y Channel from the Driving Signal pull down menu and select the Y Linearizer checkbox from the Channel list. If the signals look normal, then proceed to the next step.

Figure 14.3a Signal Tracing Window

If the linearizer signals are clipped (horizontal) near the end of the DAC voltages, the linearizer may require alignment. Refer to the scanner alignment support note (013-432-000) for details.

Ch. 14 - CalibrationCalibrating X and Y Measurements:


14.4 Calibrating X and Y Measurements:

With the Closed Loop controls for X and Y on, acquire a large area scan (close to maximum value: 100µ) of the 10µ XY Pitch, 200nm Z Height calibration grid standard that is supplied with the system accessories. Make sure that it is aligned as close to perpendicular orientation as possible so that the structure features appear to be parallel to the edges of the scan window. After the image is acquired, Left Click & Drag the image over into the Scanning control window. From the main application window menu bar, under the Setup pull down menu, choose Recalibration > XY Recalibration. Select the Angle Measurement Tool to the right of the image. Draw the X and Y axis lines along the edges of the grid pattern to measure the angle of the image skew. To start the X axis line, left click on the origin point and drag from right to left. Release the left mouse button. Then place the cursor back on the origin point and right click the mouse. Drag the Y axis line along the vertical features and release the button at the end of the desired line. The angle value is displayed in the window as the current measurement. If the value is significantly different from 90 degrees, then click the red and blue down arrow tool that opens the input dialog box. Type in the desired angle and press Enter. The crosstalk factor is calculated and displayed. (If the coefficient value reported is a positive number, change it to a negative number.) Select the ‘Use It’ arrow tool as the option to save the measurement, and the crosstalk correction factor will be entered into the scanner file. See example:

Figure 14.4a Horizontal and Vertical Reference Lines Dragged Onto Image

Ch. 14 - CalibrationCalibrating X and Y Measurements:


It is a good idea to rescan the sample at this point to make sure that the correction works properly. If further correction is necessary, continue the angle / crosstalk correction process. Collect a suitable scan of the standard grid and drag it into the Scanning control window. Choose Setup / Recalibration / XY Recalibration and activate the Distance Measurement dialog by clicking the button with the line segment icon on the right side of the Scanning window. The label “XY Recalibration” should appear on the left side of the window under the parameters input section. Click on the downward pointing red/blue arrows. To perform the X axis calibration make sure that the X radio button is selected and then draw a horizontal line across a set of features (known distance) in the image. The software will show the measured distance in the display box above the arrows. Type in the correct (nominal) distance in the Distance dialog box. Example: If your line covers 8 pitches, type in 80µ, if it covers 9 pitches type in 90µ. Repeat this procedure to calibrate the Y axis, by selecting the Y radio button and drawing the line vertically. Once completed, rescan the standard sample image and check the results.

Figure 14.4b X-axis Calibration Line Drawn

Ch. 14 - CalibrationCalibrating Z Measurement:


14.5 Calibrating Z Measurement:

Z axis calibration is performed using the Line Scan feature. First, select Z Recalibration from the Setup > Recalibration menu. Select the Line Scan mode icon from the Scanning control window. Enter the line scan parameters manually or choose a line position graphically on the image displayed in the Scanning control window using the previously acquired image of the grid. Start the Line Scan. In the Line Scan window, select the 1-D Line Fit option to avoid tilt in the line scan data. Click on the distance measurement icon on the right side of the Line Scan control window. Click on the Z Recalibration item in the Line Scan menu bar to bring up the Z Height calibration dialog box. Select the Distance Measurement icon on the right and click on the lines in the graph to select 2 cursor positions. Note that the cursors can be set on either the forward or reverse trace lines, but both cursors need to be set on the same trace to obtain a measurement. The Z Height calibration dialog will display the current measured height. Type in the known height of the reference standard (0.2 microns or 200 nm in this case) in the "New" dialog box (not in the "Range" box). Press Enter to have the value accepted by the software.

Figure 14.5a Before Typing In New Measured Height:

Figure 14.5b After Typing In the Nominal (known) Z Height:

Ch. 14 - CalibrationCalibrating Z Measurement:


14.5.1 Calibrating the Z-Linearizer:

Follow the same procedure to calibrate the Z-Linearizer.

Note: Z-Linearizer data may be inverted from height. In addition to the "Z-Linearizer" data channel, a channel named "Height Sensor" also exists on the list of available signals, which provides linearized Z measurements without the inversion. “Z-linearizer” data is always in volts while “Height Sensor” data is in nm, reflecting the current calibration factor. “Z-linearizer”, not “Height Sensor” is the data type used in the calibration procedure.

In the example below we can see a Z Lin value of 104.2mV per 200nm. This results in a factor of 1.92nm/mV.

Figure 14.5c Z-Linearizer Calibration

Ch. 15 - Thermal TuneOverview

Rev. B Innova User Manual - Ch. 15, Thermal Tune 199

Chapter 15 Thermal Tune

15.1 Overview

This chapter describes the method of Thermal Tune characterization of the probe prior to performing imaging or analysis that depends upon the spring constant of the probe or its mechanical resonance in liquid. The Thermal Tune method observes and monitors the oscillation of the probe which occurs from environmental excitation (i.e., thermal effects) which is less subject to outside influences which are present when the excitation is produced by piezo stimuli.

Various analyses or measurements such as point spectroscopy require that the spring constant of the probe be known. It may be important to have an accurate value for the spring constant to avoid damage to the sample or to avoid confounding results from one or more samples that require a change in probe. Often it is sufficient to use the spring constant information which is supplied with the probe, however, a set of probes will invariably exhibit variation. Critical applications may benefit from the Thermal tune method of determining the spring constant.

Tapping mode applications stimulate the probe at a frequency near its mechanical resonance. Determining the resonance is often difficult when imaging in liquids. Exciting the probe through a range of frequencies applied through the piezo device usually produces multiple or vague resonance peaks at several frequencies because of the damping effect of the liquid. The Thermal tune method determines the resonant frequency by determining a response peak due to thermal stimulation of the probe. This peak is a good indication of the probe resonance and the frequency may be used as a drive frequency for imaging in liquid.

Note: Thermal tune is available in SPMLab 7.11 or later. Contact Veeco if an upgrade is required.

15.2 Set-up

The thermal tune procedure is the same whether the experiment will be performed in contact mode or tapping mode. It should be noted that tapping mode imaging in liquid typically uses a probe which is also used for contact imaging in air and liquid. The probes commonly used for tapping mode imaging have high resonant frequencies in air but liquid damps the oscillation. The common choice of probe for tapping mode imaging in liquid is the short, narrow-legged DNP or DNPs. Even softer cantilevers can be used for contact mode but typically these do not perform well for tapping mode imaging in liquid.

1. Mount the specimen to be imaged. If the imaging is to be performed in liquid, the thermal tune procedure is performed with the specimen in the liquid.

2. Set-up Innova to perform contact mode imaging as described in Chapter 7 up to engaging.

Ch. 15 - Thermal TuneSet-up

200 Innova User Manual - Ch. 15, Thermal Tune Rev. B

15.2.1 Calibrate Sensitivity

Before performing Thermal tune, it is necessary to calibrate sensitivity using the procedure in Point Spectroscopy. See Chapter 10.

1. After engage is complete, select the Point Spectroscopy tool

Figure 15.2a Select Point Spectroscopy

2. This will open the Point Spectroscopy window

Figure 15.2b Point Spectroscopy Window



3. For later reference, click on the drop down window to see what the display options are. Note that only two y-axis options are available: V or µm.

Figure 15.2c Y-axis options

4. Refer to Chapter 10 if required and change the parameters in the left portion of the window as needed and generate a good force/distance plot

Figure 15.2d Produce a Force/Distance Plot

Options



5. Select the Slope/Angle measurement tool

Figure 15.2e Slope/Angle Measurement Tool

6. Move the cursor onto the slope and click, then select a second point on the slope and click again. When the second point is selected, a value for sensitivity will appear. In this example, the value is 0.0195 and it is “pasted” into the Thermal Tune procedure and will be seen again in the next section. The exact value will depend upon the cantilever type and laser adjustment. Deflection sensitivity values between 0.01 µm/V to 0.1 µm/V are typical.

Figure 15.2f Select Points to Determine Sensitivity

Point 1

Point 2

Ch. 15 - Thermal TuneThermal Tune


7. Click the Calibrate toolbutton and a Deflection Sensitivity Calibration message window will appear.

Figure 15.2g Deflection Sensitivity Calibration Completed

8. Click OK to close the window.

9. Disengage

15.3 Thermal Tune

1. Ensure that the probe is disengaged

2. Make the menu selection: Setup > Thermal Tune.

Figure 15.3a Select Thermal Tune



3. The Thermal Tune window will open. Notice that the sensitivity value 0.0195, which was determined in the previous section, is shown in this window. The spring constant value which is displayed is a remnant from some earlier analysis and is not valid. A correct spring constant will be determined later in this procedure.

Figure 15.3b The Thermal Tune Window.

Note: In the Acquisition section of the Thermal Tune window, Average is selected by default and the Continuous Scan toolbutton is also selected by default. With these settings, the spectrum analysis of probe oscillation will be performed repeatedly and a running average of the analysis displayed. For some applications it may be desired to specify a specific number of iterations by entering that number in the window in the Acquisition section. The default value of “0” results in continuously repeating/averaging spectrum analysis until the acquisition is manually stopped.



4. Clicking the Start/Stop toolbutton will begin to perform/average spectrum analyses and display the number of analyses performed in window at the bottom of the screen until the toolbutton is again clicked. The example was stopped at 209 iterations.

Figure 15.3c Example Scan

Note: The acquisition is usually permitted to continue until the average response produces a fairly smooth peak.



5. After the acquisition has been stopped, select the measurement tool in the upper right corner of the window.

Figure 15.3d Select Measurement Tool

6. Click and drag a zoom window around the response peak

Figure 15.3e Click/Drag a Zoom Window

Zoom window



7. Release the mouse button and the selected zoom area will be displayed. As the cursor is moved on the response curve the values of the curve are displayed at the bottom of the screen.

Figure 15.3f Zoomed Area Display

8. Click the Fit toolbutton to produce a curve fit of the response and display the frequency peak and Q of the response.

Figure 15.3g Curve Fit and Statistics



Note: If desired/needed, the curve fit may be removed and redrawn by clicking on the Fit toolbutton.

Note: When performing thermal tune in liquid, the observed resonant frequency is typically 1/3 to 1/2 the resonant frequency in air and Q is typically less than 100.

9. Click the Calibrate toolbutton and the spring constant value will be updated

Figure 15.3h Calibrate and Get Spring Constant

10. If the sample is to be imaged in liquid, record the peak frequency (in this example, 30.8098 kHz) as a reference for determining the tapping drive frequency. For Point Spectroscopy, the spring constant value has been “pasted” and provides an additional option in Point

Ch. 15 - Thermal TuneAdditional Options


Spectroscopy as shown in the revised window. This option allows force curves to be displayed and saved in force units.

Figure 15.3i Point Spectroscopy Option Includes μN

15.4 Additional Options

There are additional options/controls available in Thermal Tune. To access these options, click on the Extend Acquisition tool.

Figure 15.4a Extend Acquisition Tool



Additional controls are displayed

Figure 15.4b Extended Acquisition Control Options Shown

15.4.1 Input Gain

1. If Data Capture is toggled, raw data (not spectrum analysis) is displayed. The raw data should be displayed without exceeding the screen range (clipping, saturation) as shown in the example.

Figure 15.4c Gain Good



2. If the data extends out of the screen range, the input gain is set too high and must be adjusted to produce an acceptable level as illustrated in Figure 15.4c

Figure 15.4d Gain Too High

15.4.2 Check for Aliases

Unless a specific frequency range has been specified, spectrum analysis is performed from zero to the Nyquist frequency (half the sampling rate). If the peak response occurs beyond the upper limit of the range, the peak response is reflected around the upper limit. For instance, if the upper limit of frequency is 50kHz and the actual peak is at 57 kHz (that is, 7 kHz higher than the upper limit), the spectrum analysis will indicate a peak (an “alias”) at 43 kHz (i.e., 7 kHz lower than the upper limit).

To detect aliasing, enable the option Check for aliases and perform a scan. Multiple scans are performed with the sampling rate incremented upward for each scan. If aliasing is present, the

Adjustas needed



reflected peak will occur at different locations. Peaks truly located below the Nyquist frequency will appear at the same frequency (their true frequency) regardless of the sampling rateµm.

Figure 15.4e Example of Check for Aliases Display with No Aliasing

Rev. B Innova User Manual 213

Appendix A Synchronizer

Notice:

This section describes specialized applications for advanced users. Operation of the Innova system does not require familiarity with the contents of this section except for those specialized applications. In general, the majority of users may skip this section unless, and until, the Synchronizer capability is known to be required.

A.1 Introduction:

Veeco Innova Synchronizer is an option which provides the capability to synchronize the image scanning operations of an Innova AFM with the operation of another device. The synchronization is performed by handshaking signals between the two instruments. The Nanodrive controller can output handshaking signals with designated voltage levels and durations. It can also accept input handshaking signals with designated voltage levels.

The Innova synchronizer requires no additional hardware. The handshaking signals are fed in and out via the interface board installed in the standard configuration Nanodrive controller. The Synchronizer option requires SPMLab Version 7.11or higher. Contact Veeco to purchase the Synchronizer option functionality and refer to option part number INSYNC.

Appendix A: SynchronizerSet-up

214 Innova User Manual Rev. B

A.2 Set-up

A.2.1 Handshaking Out-put Signals

1. Use a BNC cable to connect the “OUT2” output on the NanoDrive back panel to the accepting terminal of the synchronizing device.

Figure A.2a BNC Connections

OUT2



2. Select Realtime Control > Synchronizer Control.

Figure A.2b Menu Selection for Synchronizer Window.

3. In the Synchronizer window, specify the pulse required by the synchronizing device.

Check boxes:

• Active: checked.

• Handshake: unchecked.

• Test: checked. (Changes the Apply button to Run for testing synchronization handshaking. When imaging, Test should be unchecked.)

Figure A.2c Synchronizer Window Output Checkboxes



Pulse Characteristics: (see Figure • and Figure A.2d)

• High level: the upper level of the output voltage pulse.

• Low level: the lower level of the output voltage pulse.

• Pulse width: the duration of the voltage pulse (in milliseconds.

Figure A.2d Output Pulse Illustration

CAUTION: Ensure the output voltage levels are compatible with the receiving device to prevent electronics damage.

4. When the Run button is clicked, the NanoDrive controller outputs a single pulse. During the output, the Synchronizer window becomes temporarily busy, depending on the pulse width, then returns to the idle state.



A.2.2 Set Up Handshaking Input Signals

1. Connect a BNC cable between "IN2" connector on the NanoDrive back panel to the output terminal of the synchronizing device.

Figure A.2e IN2 BNC Connection on Nanodrive

IN2



2. In the Synchronizer window, define the Nanodrive input handshaking pulse.

Checkboxes: (see Figure A.2f)

• Active: checked.

• Handshake: checked.

• Tuning: checked.

Figure A.2f Synchronizer Window Input Checkboxes

“LED” indicator



3. Pulse characteristics: (see Figure A.2g)

• High level: the upper level of the input handshaking pulse. Maximum: 10V.

• Low level: the lower level of the input handshaking pulse. Minimum: -10V.

• Rising Edge: When checked, the rising edge is used for handshaking, otherwise, the falling edge is used.

Figure A.2g Handshake Sequence (a) Rising Edge and (b) Trailing Edge

4. Click Run. The NanoDrive controller should immediately output a voltage specified by “high level” in the “Pulse Out” section, then wait for the handshake signal to lower the output to the “low level”. The small LED (see Figure A.2f) indicates the status of the handshake signal. It has three states:

• green: ready to use the handshake

• red: waiting for handshaking signal.

• gray: inactive (handshake cannot be used).

HandshakeOutput Signal

HandshakeInput Signal

Appendix A: SynchronizerConfigure Software


A.3 Configure Software

1. Specify the handshaking signals as described in the preceding sections.

2. Un-check the Tuning selection and click Apply to activate the synchronizer.

Figure A.3a Activate the Synchronizer

3. Open the Scanning Conditions window using the menu selection Conditions.

Figure A.3b Menu Select Conditions

Appendix A: SynchronizerConfigure Software


4. In the "Scanning conditions" window, select the operations to be synchronized.

Figure A.3c Select Synchronization Operations

5. The available operations include:

Image operations:

Beginning: When checked, the Nanodrive controller outputs a specified handshaking output signal when it is ready to begin a new image scan. If Handshake is enabled (see the checkbox in Figure A.3a), Nanodrive will wait for a handshaking input signal to start the scan.

End: When checked, the Nanodrive controller outputs a specified handshaking output signal when it finishes scanning an image.

Forward line:

Beginning: When checked, the Nanodrive controller outputs a specified handshaking output signal when it is ready to begin a scan line in the forward direction. If Handshake is enabled (see the checkbox in Figure A.3a), Nanodrive will wait for a handshaking input signal to start the scan.

End: When checked, the Nanodrive controller outputs a specified handshaking output signal when it finishes scanning a line in the forward direction.

Pixels: When checked, the Nanodrive controller outputs a specified handshaking output signal when it is ready to move to the next pixel in the forward direction. If Handshake is enabled (see the checkbox in Figure A.3a), Nanodrive will wait for a handshaking input signal to start the scan.

Backward line:

Beginning: When checked, the Nanodrive controller outputs a specified handshaking output signal when it is ready to begin a scan line in the backward direction. If Handshake is enabled (see the checkbox in Figure A.3a), Nanodrive will wait for a handshaking input signal to start the scan.

End: When checked, the Nanodrive controller outputs a specified handshaking output signal when it finishes scanning a line in the backward direction.

Appendix A: SynchronizerRun Synchronizer


Pixels: When checked, the Nanodrive controller outputs a specified handshaking output signal when it is ready to move to the next pixel in the backward direction. If Handshake is enabled (see the checkbox in Figure A.3a), Nanodrive will wait for a handshaking input signal to start the scan.

Note: Since the end of a forward line is usually also the beginning of the next backward line, Nanodrive will output two handshaking pulses when both checked. The same is true for the end of backward line and the beginning of forward line.

5. Click OK to apply the selected synchronizations.

A.4 Run Synchronizer

1. In the Scanning control window, click the Start/Stop scanning button to start scanning and synchronization will be performed.

Figure A.4a Start Scanning Will Apply the Synchronization Setup

2. To change synchronization operations, stop scanning and change parameters described in Section A.3.

3. To change synchronization signal levels, change values in the synchronizer window and click Apply.


Appendix B Open Hardware

Note:

This section describes specialized applications for advanced users. Operation of the Innova systemdoes not require familiarity with the contents of this section except for those specializedapplications. Even advanced modes such as Scanning Capacitance Microscopy do not usuallyrequire Open Hardware features. In general, the majority of users may skip this section unless, anduntil, the Open Hardware capability is known to be required.

B.1 Introduction

The included Open Hardware feature provides wide flexibility in the configuration of the Innova system. The Open Hardware option provides access to the configurable electronics including: DACs, ADCs, Multiplexers, lock-in amplifiers, signal generators, and others. With Open Hardware access, the various accessible items may be configured as needed for special requirements of imaging or testing.

It is important to understand several aspects of the Open Hardware feature:

• Any changes made are implemented immediately.

• The default SPMLab values will appear in the various control windows until Get Parameters is executed.

• There are no safeguards. Reversing feedback or other actions can cause the system to behave erratically and may result in damage to the probe and/or sample.

• None of the changes made using Open Hardware controls will be saved. By closing and re-opening SPMLab, all normal default conditions will be restored.

Open Hardware is available in SPMLab Vr. 7.10 r1 or later.

Open HardwareSoftware Setup


B.2 Software Setup

1. Menu select: Tools > Open HW Access.

Figure B.2a Open Hardware Access Selection

2. Note the caution in the pop up message window. When ready to proceed, click Yes. If No is clicked, the operation will be stopped.

Figure B.2b Caution: Open Hardware Access for Advanced Users!

Open HardwareSoftware Setup

Rev. G Innova User Manual 225

3. The Open hardware tool bar will display on the right side of the SPMLab main window.

Figure B.2c Toolbar for Open Hardware Access

The tool button functions are:

Feedback control

Multiplexers control

DAC and ADC control

Tip voltage control

IOMOD control (dual channel lock-in)

Innova Interface board control (IO-I)

Innova High Voltage board control (IO-HV)

Open HardwareOpen Hardware System Diagram


B.3 Open Hardware System Diagram

The Open Hardware functions allow the user to take direct control of electronics hardware in the NanoDrive controller. The following section describes the Innova system and NanoDrive controller in great detail.

B.3.1 Innova Systems Diagram

Figure B.3a displays the main components of the Innova system. The three main components are the SPM Instrument, the NanoDrive Controller and the PC. During normal operation, the DSP inside the NanoDrive controller controls the Instrument, receives commands from the PC and sends data back to the PC.

Figure B.3a Innova Systems Diagram

O

pti

on

al e

xte

rnal

sig

nal

acc

ess

SPM

Instrument(Innova)

PC

HV Board

(IO-HV)

NanoDrive Controller (configured for Innova)

DSP Board

(DSP & FPGA)

Dig

ita

l B

us

Data Acquisition

Board

Interface

Board

(IO-I)

Lock-in

Board (IO-MOD+)

Optional Boards:

IO-X signal access An

alo

g B

us

USB



The sub-functions of the NanoDrive controller are split over a number of modular boards:

1. Data Acquisition board:

• This board handles most of the Analog to Digital conversions (ADC) and a number of the Digital to Analog conversions (DAC). It interacts with the other boards through the digital and analog bus.

2. IO-I Interface board:

• This board interacts directly with the Innova SPM instrument and handles all of the low voltage signals coming and going to the instrument.

3. IO-MOD+ Lock-in board:

• This is a two channel lock-in board that is, as an example, used during Tapping mode to generate the Tapping drive and determine the Tapping amplitude and phase. It normally interacts with the other boards through the analog and digital bus, but has powerful input and output capabilities through the BNCs mounted on its front panel.

4. IO-HV High Voltage board:

• This board generates all the high voltages needed for the scan motion.

5. Optional boards:

• Additional boards, such as the IO-X Signal Access board, can be placed in the NanoDrive controller and interact with the other boards through the analog and digital bus.



B.3.2 Open Hardware Access Controls

The Open Hardware feature in the software allows for direct interaction with the different boards in the NanoDrive controller, outside of the normal SPMLab software routine. The diagram in Figure B.3b gives an overview of the Open Hardware functions and where they interact with the NanoDrive controller.

Figure B.3b Open Hardware Functions Diagram

HV Board High voltage enable/disable

switchable High/Low gain

Monitor connections to bus

Z-Voltage source selection

NanoDrive Controller (configured for Innova)

DSP Board Main clock

XYZ Feedback selection and

settings

Dig

ita

l B

us

Data AcquisitionBoard 8 ADC channels with input selection with filters, gain,

offset

64-to-1 multiplexer for monitoring selection

13 DAC channels (24bit(x1), 16bit(x4), 12bit(x8)

Tip voltage control

Interface Board(IO-I) Switchable connections to the bus

Switchable BNC outputs

Dither drive selection

Tip sample bias selectors

Lock-in Board Two lock-in channels with drive signal generation,

amplitude control, variable gains and filters, switchable

bus inputs and outputs, switchable BNC outputs

Optional Boards:

IO-X signal access

An

alo

g B

us

Open HardwareInput/Output Signal Access


B.4 Input/Output Signal Access

The Open Hardware functionality includes the ability to access input and output signals using BNC connectors situated on the backside of the NanoDrive controller as described in the following section.

Additional access points exist on the back of the Innova microscope base via four BNC connectors, however, the BNC connectors on the microscope base are used almost exclusively for electrochemistry. Thus, they do not play a significant role for the Open Hardware functionality described in the following section.

In particular, AUX1 on the back of the microscope base provides STM bias options in electrochemistry, AUX2 is connected to sample bias (work electrode in electrochemistry), AUX3 is connected to tip bias (black pin on microscope stage, serves as counter electrode in electrochemistry), and AUX4 is used as reference electrode access in electrochemistry (via red pin on stage, through a buffer amplifier). When not in electrochemistry mode, AUX4 functions as floating differential input that can be configured using Open Hardware Access and connected to an ADC via AL3. However, AUX4 cannot be used with STM as AL3 serves as STM current line. The outside shells of BNCs 1 to 3 are connected to analog ground.

For general purpose input and output, use the BNC connectors on the backside of the NanoDrive controller, rather than those on the backside of the microscope.

B.5 Open Hardware Functions

B.5.1 Feedback Control

Open the Feedback Control window by clicking on the Feedback Control toolbutton.

Open HardwareOpen Hardware Functions


Figure B.5a Feedback Control Window

Feedback controls/Parameters:

• DSP Clock: Main FB period in µsec. This changes the overall speed of the controller. At values below 10.0 µsec. (= 100kHz), errors may occur on some applications

• X/Y/Z Channel: For each of the Z, Y and X Channel sections, the PID Coefficients are different from the feedback values in the SPMLab main window GUI. The values in this window are the actual values applied to the hardware feedback loops while the values in the GUI are scaled for convenience.

• Inverse: When checked, the polarity of the feedback signal is reversed.

Note: Reversing the feedback loop will cause system oscillation.

• On: When unchecked, the feedback loop is inactive. When checked, the feedback operation is active. The value is the actual value of the target under feedback control (feedback input signal).

• Setpoint: The set point value for the feedback loop.

• ADC: The ADC used to measure the input signal that is under feedback control.

• DAC: The DAC used to output a signal to exercise control

• Get Parameters Button: When clicked all the parameters in the window are updated to display the current status of all the parameters in the window. To change any parameter or setting, change the parameter and <Enter> from keyboard.

B.5.2 Multiplexer Control

Open the Multiplexers Control window by clicking the Multiplexers control toolbutton.

Figure B.5b Multiplexers Control Window



This dialog permits setting the multiplexers present on the data acquisition board. There are two types of multiplexers. The first type has 16 inputs and the output feeds an ADC channel. The second is a 64-to-1 multiplexer that can be used to access more signal lines and is primarily used in the Oscilloscope and Multimeter functions.

The 16-to-1 ADC Multiplexers

Each ADC channel has one 16-to-1 multiplexer. Since there are 8 ADC channels there are also 8 such multiplexers. Seven of them, those that are associated with ADCs 0 through 6, are freely accessible through the multiplexer dialog. See the upper section of the dialog shown in Figure B.5b. Since all of these ADC channels have identical functions, their control is combined in that upper section. The general functions of the selection boxes in the dialog are shown in Figure B.5c.

Figure B.5c ADC Multiplexer Diagram

LPF

50 kHz

10

kH

z

2 k

Hz

Gai

n

+

×1

×9

Off

set

Offset

DAC

Lin

e

MUX

AL

0..

AL

15

ADC

0..6



In standard SPM applications the analog lines (AL) have pre-defined signals on them, generated by the different boards in the NanoDrive controller. Table B.5d lists the signals on the AL lines per application. It also lists the default ADC that is used by the SPMLab software to monitor those signals. The actual ADC number assigned to a certain signal can vary depending on software configuration.

Table B.5d Analog Lines with Default ADC Selections

So the multiplexer dialog can be used to change signal lines assigned to a certain ADC. For example, when in Tapping Mode, ADC5 can be switched over from AL0 to AL9. Now instead of reading the deflection signal it will read the signal that is input on BNC IN1 on the IO-I board. Be aware that the SPMLab software will still name the signal as “deflection” signal even though it will show the IN1 signal as it is unaware of any changes made through the Open Hardware controls.

Modes:

Analog

LineSignal

Con

tact

Mod

e

Tapp

ing

Mod

e

STM

LC

STM

EC

-con

tact

EC

-tap

ping

EC

-ST

M

C-A

FM

SCM

Piez

o R

espo

nse

Forc

e M

odul

atio

n

Surf

ace

Pote

ntia

l

AL0 Deflection Signal ADCO ADC5 ADC0 ADC5 ADC0 ADC0 ADC0 ADC0AL1 Lateral Signal ADC1 ADC1 ADC0 ADC4 ADC4AL2 SUM

AL3 STM Sensor ADC0/4 ADC0/4

AL4

Tapping Amplitude ADC0 ADC0 ADC ADC0SCM Phase ADC5

LC-STM Sensor ADC0/4C-AFM Signal ADC5

PRM Signal ADC6FMM Phase ADC6

AL5SCM Feedback Bias ADC6

SEPM Potential ADC6AL6 X LIN ADC3 ADC3 ADC3 ADC3 ADC3 ADC3 ADC3 ADC3 ADC2 ADC3 ADC3 ADC3AL7 Y LIN ADC2 ADC2 ADC2 ADC2 ADC2 ADC2 ADC2 ADC2 ADC1 ADC2 ADC2 ADC2AL8 Z LIN ADC1 ADC1 ADC1 ADC1 ADC1 ADC1 ADC1 ADC1 ADC1 ADC1 ADC1AL9 IN 1 ADC5 ADC5 ADC5 ADC5 ADC5AL10 IN 2 ADC6 ADC6 ADC6 ADC6 ADC6

AL11

Tapping Phase ADC4 ADC4SCM Amplitude ADC5PRM Amplitude ADC5FMM Amplitude ADC5

SEPM Error ADC5

AL12SCM Detector ADC3Tapping Phase ADC4

AL13T_B Fast Filtered √

SCM Sensor √AL14 T-B Fast √ √ √ √ √AL15 ADC6 ADC6 ADC6



ADC7 and the Monitor Multiplexer

The eighth 16-to-1 multiplexer, which is associated with ADC 7, is typically used for the built-in oscilloscope function. That means its channel setting is automatically changed to access all channels sequentially. To control this multiplexer manually, the “Oscope Enable” button must be unchecked (see middle section of Multiplexer Control dialog shown in Figure B.5b). The second type of multiplexer has 64 inputs. It too is typically controlled by the oscilloscope function. To control it manually, the “Oscope Enable” button must be unchecked. The output of the 64-to-1 multiplexer is driven onto AL15. Hence, to read any of its inputs, one of the 16-to-1 multiplexers must be set to AL15 and the corresponding ADC must be read via software. It is also possible to access AL15 electrically through several of the signal access BNCs. The following table lists the input functions of the 64-to-1 multiplexer.

Table B.5e Monitor Line Assignments

The Gmon and HVmon signals come from interface boards. Unless they are enabled there, these signals are open inputs. When open, they are not constrained and typically drift towards a rail.

NR Description NR Description0 GMon0 (must be enabled elsewhere) 32 DACmon0 (VTIP)1 GMon1 (must be enabled elsewhere) 33 DACmon12 GMon2 (must be enabled elsewhere) 34 DACmon23 GMon3 (must be enabled elsewhere) 35 DACmon34 GMon4 (must be enabled elsewhere) 36 DACmon45 GMon5 (must be enabled elsewhere) 37 DACmon56 GMon6 (must be enabled elsewhere) 38 DACmon67 GMon7 (must be enabled elsewhere) 39 DACmon78 GMon8 (must be enabled elsewhere) 40 DACmon89 GMon9 (must be enabled elsewhere) 41 DACmon910 GMon10 (must be enabled elsewhere) 42 DACmon1011 GMon11 (must be enabled elsewhere) 43 DACmon1112 GMon12 (must be enabled elsewhere) 44 DACmon1213 GMon13 (must be enabled elsewhere) 45 3.3 V digital supply14 GMon14 (must be enabled elsewhere) 46 5.0 V digital supply15 GMon15 (must be enabled elsewhere) 47 DGnd digital ground reference16 HVMon0 (must be enabled elsewhere) 48 +15V analog supply (div. by 2)17 HVMon1 (must be enabled elsewhere) 49 -15V analog supply (div. by 2)18 HVMon2 (must be enabled elsewhere) 50 +5V supply of DACs19 HVMon3 (must be enabled elsewhere) 51 -5V supply of DACs20 HVMon4 (must be enabled elsewhere) 52 5.00V reference for calibration21 HVMon5 (must be enabled elsewhere) 53 -5.00V reference for cal. verification22 HVMon6 (must be enabled elsewhere) 54 2.50V reference for cal. verification23 HVMon7 (must be enabled elsewhere) 55 AGnd analog signal reference24 HVMon8 (must be enabled elsewhere) 56 5V supply of ADC0 and ADC125 HVMon9 (must be enabled elsewhere) 57 5V supply of ADC2 and ADC326 HVMon10 (must be enabled elsewhere) 58 5V supply of ADC4 and ADC527 HVMon11 (must be enabled elsewhere) 59 5V supply of ADC6 and ADC728 HVMon12 (must be enabled elsewhere) 60 +15V digital supply (div. by 2)39 HVMon13 (must be enabled elsewhere) 61 -15V digital supply (div. by 2)30 HVMon14 (must be enabled elsewhere) 62 Unused, open31 HVMon15 (must be enabled elsewhere) 63 Unused, open



Detailed Control Descriptions

The Multiplexer Control window is divided into three sections:

Section 1 = 0-6 ADC muxes: ADCs from no.0 to no.6 can be configured to take different signals for each ADC. Additionally, each ADC can also be individually configured for offset, gain and filters.

• ADC channel: Selects the ADC to configure.

• Line: Selects the signal to be routed to the ADC

• Offset: When checked, offset to ADC signal is enabled.

• Gain: When checked, gains to ADC signal are enabled.

• 10 kHz filter: When checked, the 10 kHz filter is enabled.

• 2 kHz filter: When checked, the 2 kHz filter is enabled.

• Red arrow button : When clicked, applies the settings to the selected ADC.

• Question Mark button : When clicked, retrieves the settings for the selected ADC channel. Whenever a new ADC is selected, the Question Mark button must be clicked to display settings for that ADC.

Section 2 = 7th ADC muxes: ADC no.7 can be set up to take different signals. This is implemented by configuring the mux. Additionally, the output of this ADC can also be configured to display on the oscilloscope window.

• Line: Selects the signal to be routed to this ADC

• Disable: When checked, ADC 7 is disabled.

• Oscope Enable: When checked, data is displayed in the oscilloscope window.


• Question Mark button : When clicked, retrieves the settings for ADC #7.

Section 3 = 64x1 mux: Multiplexer controls which signal is routed to AL15 (which can then be measured by an ADC.

• Line: Selects the signal to be routed to AL15.

• Disable: When checked, routing is disabled.


• Question Mark button : When clicked, retrieves the settings for ADC #7.



B.5.3 DAC and ADC Control

This window allows one to directly set certain DAC outputs and read the ADC values. Table B.5f lists the DACs that can be set. Some DACs are continuously updated through the regular SPMLab software and will not retain the value set by this dialog. For example, in the closed-loop XY operation setting, the X-DAC will momentarily set the X-DAC to a different value, but 10µsec later the closed-loop feedback will correct the position offset and change the X-DAC output correspondingly.

Note: When the tip is engaged or close to the sample, changing the DAC values can result in tip or sample damage.

Table B.5f Available DACs with Description

DAC# DescriptionDAC0 - XDac Low Voltage XDAC1 - YDac Low Voltage YDAC2 - ZDac Low Voltage Z

DAC3 - VTip Dac Tip or Sample Bias VoltageDAC4 - Aux Dac1 Auxiliary DAC1DAC5 - Aux Dac2 Auxiliary DAC2DAC6 - Aux Dac3 Auxiliary DAC3DAC7 - Aux Dac4 Auxiliary DAC4DAC8 - Aux Dac5 Auxiliary DAC5DAC9 - Aux Dac6 Auxiliary DAC6DAC10 - Aux Dac7 Auxiliary DAC7DAC11 - Aux Dac8 Auxiliary DAC8DAC12 - Aux Dac9 Auxiliary DAC9

DAC13 - Aux Dac10 Auxiliary DAC10DAC14 - Aux Dac11 Auxiliary DAC11DAC15 - Aux Dac12 Auxiliary DAC12DAC16 - Offset Dac0 Offset DAC for ADC0DAC17 - Offset Dac1 Offset DAC for ADC1DAC18 - Offset Dac2 Offset DAC for ADC2DAC19 - Offset Dac3 Offset DAC for ADC3DAC20 - Offset Dac4 Offset DAC for ADC4DAC21 - Offset Dac5 Offset DAC for ADC5DAC22 - Offset Dac6 Offset DAC for ADC6DAC23 - Offset Dac7 Special purpose



Open the DACs & ADCs window by clicking .

Figure B.5g DACs & ADCs Window

• DAC: Use the drop down list to select the desired DAC and move the slider control to adjust the DAC output for each DAC of interest. The output range is from –10V to +10V for each DAC.

• ADC: Use the drop down list to select the desired ADC. Enable the ADC readout by

clicking the red LED button . When enabled the LED button will turn green

and the value of the ADC will be displayed.

B.5.4 Tip/Sample Voltage Control

Use this dialog to set the tip or sample bias voltage directly, or to add a modulation voltage to the tip or sample bias. The VTMOD signal allows one to add a modulation signal to the tip or sample bias. The VTMOD amplitude and frequency are set in the IOMod Control dialog and the VTMOD signal needs to be enabled in the IOMod Control dialog. By selecting both “Enable” and “VMOD” the bias voltage will have both the DC and AC components.

A schematic diagram of the controls is shown in Figure B.5h.

Figure B.5h Tip/Sample Bias Control Diagram

VTIP DAC

Enable

+VMOD/100

+VMOD

VTIP

VTMOD

/100



Open the VTIP Control window by clicking on the toolbutton.

Figure B.5i VTIP Control Window

• Slider: Adjust to desired tip voltage. Range is from –10V to +10V.

• + VMOD/100: Green = Routing to +VMOD/100. Red = Inactive.

• + VMOD: Green = Routing to +VMOD. Red = Inactive.

• Enable: Green = Active. Red = Inactive.

• Get Parameters: Retrieves the status of tip voltage control.



B.5.5 IOMod+ Control

This dialog allows for the full control of the dual channel lock-in. Any changes made in this dialog are applied instantaneously, however, the parameters are not updated if the window is already open and some of the values are changed using the regular SPMLab software controls (like the cantilever tuning window). Use the “Get Parameters” button when switching back and forth between the IOMod Control dialog and the regular SPMLab functions.

Open the IOMOD Control window by clicking the toolbutton.

Figure B.5j IOMod Control Window

• Sections 1&2: Controls for Lock-in amplifiers A or B.

• Amplitude: The lock-in drive signal amplitude (peak-to-peak).

• Frequency: The lock-in operating frequency.

• Drive Phase: The lock-in reference signal phase.

• Demod phase: The phase lag for the lock in amplifier.

• Source: The signal to be analyzed by this channel.

• Input BNC Shell is Grounded: When checked, input BNC shell is grounded.

• Input Gain: Gain applied to input signal before performing lock-in analysis.

• Post Gain: Gain applied to input signal after performing lock-in analysis.

• Filter select: Types of filters to be applied.

• Filter Freq: Filter cut off frequency.



• Section 3: Analog Lines.

• AL4: Signal to be routed to AL4.



• Section 4: BNC.

• BNC1: Signal to be output through BNC1 on the IOMod+ board (at rear of Nanodrive controller).

• BNC2: Signal to be output through BNC2.



• Section 5: Modulating Signal Enable.

• Z_BI_MOD: Green = Apply the Drive of Channel A to the Z-BI-MOD line. Use the “Dither Drive Source” in the IOI Board control window to connect that line to the dither piezo. Red = Disabled.

• Z-MOD: Green = Apply the Drive of Channel A to the Z-MOD line. Use the “Z-Voltage Sources” selector in the IO-HV Control window to connect the Z-MOD line to the Z-piezo, or as addition to the regular Z-DAC voltage. Red = Disabled.

• VTMOD: Green = Apply the Drive of Channel A to the VTMOD line. Use the “VTIP Control” window to add this modulation voltage to the regular tip or sample bias. Red = Disabled.



B.5.6 Innova Interface Board Control

This dialog controls the Innova Interface Board (IO-I board). It allows for putting certain signals on analog lines (AL), selecting the sources for generic output BNCs and selecting the sources for the dither and bias voltages. Always avoid turning on multiple signals for the same AL line. Turn off connections first, before making new connections.

Open the Innova Interface Board window by clicking the toolbutton.

Figure B.5k Innova Interface Board Control

• Input →AL Connections: Controls the routing of signals. Mark check boxes of desired options.

• Out BNCs: Controls the routing of signals to the two BNCs on the IO-I board (at rear of NanoDrive controller).

• Out 1: Signal to be output through OUT1 BNC.

• Out 2: Signal to be output through OUT2 BNC.

• Dither Drive Sources: Controls the routing of signals to be applied to the dither piezo.

• ZMOD BNC to dither: Green = overrides the dither drive source selection and connects the dither to the ZMOD BNC on the IO-I panel. Red = disabled.

• Bias Voltage Sources: This is to select the control of tip/sample/STM bias.

• Tip: Controls the tip voltage.

• Sample: Controls the sample voltage.

• STM/NC: Controls the STM voltage.

• Get Parameters? Updates the status of all parameters in this window.



B.5.7 High Voltage Board Control

This dialog controls the Innova High Voltage board (IO-HV board). It allows selection of the low voltage Z sources (which is the input of the high voltage amplifier), enabling of monitor lines, selection of the high voltage gain and enabling or disabling of individual xyz outputs.

Schematic diagrams of the high voltage controls are shown in Figure B.5l through Figure B.5p.

Figure B.5l High Voltage Controls Diagram 1

Figure B.5m High Voltage Controls Diagram 2



Figure B.5n High Voltage Controls Diagram 3

Figure B.5o High Voltage Controls Diagram 4



Figure B.5p High Voltage Controls Diagram 5

Open the High Voltage Board window by clicking the toolbutton.

Figure B.5q Innova High Voltage Board, PRIMARY

• Z voltage Source: Selects the voltage source applied to the piezo tube for Z motion. The selected checkbox source is activated.

• Monitor Lines: Selects the signals to be monitored. The checkbox activates the selected signal (group).

• HV Enable: Enable / Disable the high voltage.

• When pressed, enables the high voltage output for all X/Y/Z.

• When pressed, enables the high voltage output for Z.

• When pressed, enables the high voltage output for Y.

• When pressed, enables the high voltage output for X.

• Low Gain: This is to enable / Disable the low gain option for X/Y/Z.

Open HardwareExamples


• X: When checked, enables the low gain option for X.

• Y: When checked, enables the low gain option for Y.

• Z: When checked, enables the low gain option for Z.

• Get parameters? Updates the status of all the parameters in this window.

B.6 Examples

B.6.1 Changing a Signal on a Channel

This example shows how to reconfigure an ADC input to another source. It is a way to add external signals to the measurement channels or look at signals that are not configured by default. This example shows how to use IN2 on the IO-I board as input during Tapping Mode imaging.

Note: The input signal always has to be between -10V and +10V!

Start with the assumption that the system is configured for Tapping Mode. From Table B.5d, it can be seen that by default the IN2 channel or the IO-I board is not being measured. Another way to see is by opening up the channels list in the scanning control window, see Table B.6a.

Figure B.6a Default Channel Selection for Tapping Mode

To add IN2 as one of the measurement channels, the following steps need to be executed:

1. First open the Open Hardware panel, if it is not already open.



2. Open the IO-I board control and enable IN AUX2 to AL10.

Figure B.6b Enable AUX IN2

3. From Table B.6a choose a signal that will be replaced with the IN2 signal. For example, since we are in Tapping Mode we can safely replace the TM Deflection signal with IN2. Be careful, especially if you are replacing one of the critical signals, such as Tapping Amplitude, which is used for feedback.

4. From Table B.5d, it can be seen that the Deflection signal in Tapping Mode by default is assigned to ADC5. Open the Multiplexer Control window and verify by selecting first ADC Channel 5, and then clicking on the “?”.

Figure B.6c Multiplexer control with ADC5 Queried

5. Figure B.6c shows that by default ADC5 was assigned to AL0, which is the deflection signal. Now change the line to AL10 (=IN2) and press the arrow button to apply the change.

Figure B.6d Multiplexers with AL10 assigned to ADC5

6. Depending on the signal type additional filters can be applied. Figure B.6d shows an additional 2kHz low pass filter applied to the input.



7. All that is left if to connect the external signal (between -10V and 10V) to IN2 of the IO-I board.

8. The “TM Deflection” signal now will show the IN2 signal. However, the regular SPMLab software is not aware of the changes, so the default names will still be listed as “AL0 - TM Deflection” even though it now really is “AL10 - IN2”.

Figure B.6e Reconfigured Signal

9. By changing modes or restarting SPMLab, the default configuration will be reloaded and all changes made with the Open Hardware panel are overwritten.

B.6.2 Changing the Lock-in Output to Amplitude Times Cos (Phase)

In Tapping Mode, by default, the system feeds back on the Amplitude of the cantilever oscillation. This can be easily changed using the Open Hardware panels.

This example assumes that everything was already setup correctly to do regular Tapping Mode imaging using the SPMLab default settings. Follow the next steps to change the z-feedback from Amplitude to Amplitude x cos(phase):

1. It is highly recommended to withdraw the tip from the surface. Changing feedback signals can easily lead to instable feedback loops and result in tip or sample damage.

2. Open the Open Hardware panel if that is not already open.

3. Open the IOMod+ Control window and select “Get Parameters” to fill in the current parameters.

Figure B.6f IOMod+ Control Dialog Before Making Modifications

4. In Tapping Mode, by default, the system is set to feedback on Amplitude, which is AL4. See Table B.5d for details.



5. The quickest way to change this to Amplitude x cos(phase) is to click the selection box in the top right of the IOMod+ Control dialog and select “Signal x COS (phase)” as the AL4 line signal.

Figure B.6g IOMod+ Control Dialog Showing the Options for AL4

6. Verify that the feedback loop still has the correct sign, e.g. z is retracted when the signal is smaller than the setpoint, and re-engage to the sample. Feedback polarity can be switched in the “Feedback Controls” dialog, see Section B.5.1.

B.6.3 Turning on the 2kHz Low Pass Filter for a Measurement Channel

This example shows how to change the default filter settings in front of the ADC measurement channels. The first step is to find out which ADC carries the signal on which to apply the extra filtering. Use Table B.5d to determine which analog line and which (default) ADC carry the signal.

For example, to add a filter to the IN1 signal in contact mode:

1. Open the Open Hardware control panels

2. Open the Multiplexer Control dialog

3. Verify that AL9 (=IN1) is connected to ADC5 by selecting ADC channel 5 and pressing the “?” button. This will also list the default filter settings for that channel.

Figure B.6h Default ADC5 Settings in Contract Mode



4. Now select the filter settings you want to use and hit the arrow button to apply the change.

Figure B.6i ADC5 with Additional 2kHz Low Pass Filter Set

B.6.4 Z-Feedback on a Different or External Channel

This example shows how to change the z-feedback to a different or external signal. If the switch over has to happen while the tip is engaged on the surface, it is highly recommended to do a “dry run” with the tip disengaged from the surface, in order to make sure all feedback settings are correct.

There are a few options on how to switch feedback signal through the Open Hardware panels:

1. Change the feedback ADC# in the Feedback Control window

2. Change the AL line assignment to the feedback ADC using the Multiplexer Control dialog

3. Change the signal on the AL line, for example through the IOMOD+ control dialog.

B.6.5 Switching to Deflection Mode Feedback During Tapping Mode Imaging

1. Open the Open Hardware panels.



2. Open The Feedback Control dialog and press the Get parameters button.

Figure B.6j Feedback Control Dialog During Tapping Mode

3. Figure B.6j shows that in Tapping Mode the default z-feedback ADC is #0, and that the “Inverse” box is unchecked during Tapping Mode.

4. In contact mode the “inverse” box for this dialog is checked. This discrepancy is due to the difference in behavior of the deflection versus amplitude signal. The deflection signal increases with increasing bend of the cantilever (=decreasing tip-sample distance) whereas the amplitude decreases with decreasing tip-sample distance.

5. From Table B.5d it can be seen that during Tapping Mode the deflection signal is present on AL0 and assigned to ADC5 by default. It is good practice to verify the assignment by opening up the Multiplexer Control dialog. Select ADC channel 5 and press the “?” button.

Figure B.6k Verification of the ADC5 to AL0 Assignment

6. In order to switch the feedback over from Tapping Amplitude to TM Deflection, go back to the Feedback Control window:

a. Temporarily disable feedback by deselecting the “On” box.



b. Check the “inverse” box.

c. Change the Z-channel ADC to #5.

d. Change the setpoint to an appropriate value for contact mode feedback.

e. Change the PID parameters if needed.

f. Turn the feedback back on by checking the “on” box.

Figure B.6l Feedback Control Dialog with Feedback on ADC5

B.6.6 Nanomanipulation at Contact Force

The example described in 5.5 can be used to do Nanomanipulation at a contact force.

1. First take an image in Tapping Mode or the sample.

2. Now use section 5.5 to switch to contact mode.

3. Drag and drop the previously taken image in the Scanning Control window.

ba, fcd

e



4. Switch to tip positioning.

5. By moving the tip position around you can manually scratch or press on the surface. The setpoint will determine the mount of force applied.

6. Reversing the steps of section 5.5 will turn the system back into Tapping Mode.

7. Now you can take another image to see the results of the nanomanipulation.

B.6.7 Second-Harmonic Detection

This example shows how to use the 2nd channel of the lock-in to detect the 2nd harmonic component of the cantilever oscillation.

First, setup the system for regular Tapping mode, and take an image. By default it will use the first lock-in channel (channel A) to measure the amplitude of the cantilever oscillation. The second channel (channel B) is not used, so that channel can be configured to look at the second harmonic of the cantilever oscillation.

Use the following steps to set this up:

1. Open the Open Hardware panels.

2. Open the IOMod+ control dialog.

3. The Tapping drive frequency is displayed in the Channel A - frequency box. However, the number of digits at which the frequency is displayed is less than the accuracy at which was set using the Tuning window. So in order to accurately set the 2nd harmonic we must first set the Channel A frequency to an exact value. For example, the cantilever frequency in Figure B.6m was set to



328.2845 kHz but in order to know the frequency exactly a value of 328.29 was typed into the frequency box of Channel A.

Figure B.6m IOMOD+ Control Dialog Set-up for 2nd Harmonic Detection

4. Now, multiply the frequency of Channel A by a factor 2 and use that as the frequency of Channel B.

5. Switch the Source for Channel B to AL14. This is the fast deflection signal and the same source as Channel A.

6. In the “Analog Lines” section of the IOMod+ Control dialog, switch the AL12 line to the Amplitude of Channel B.

7. Open up a Multimeter window and display AL12.

Figure B.6n Multimeter Displaying the Second Harmonic Signal on AL12

8. Set the Post Gain for Channel B to x2.

9. Increase Input Gain for the Channel until the reading on the Multimeter shows a reasonable signal, somewhere between 1V and 5V is recommended.

10. The 2nd harmonic signal is now available on AL12 and all that is left is to connect AL12 to one of the measurement ADCs. For example, the TM Deflection signal can be swapped with AL12.



For this, open up the Multiplexer Control window and find the ADC that is looking at the TM Deflection signal. By default this is ADC5 connected to AL0.

Figure B.6o ADC5 connected to AL12 with additional filtering applied

11. Connect ADC5 to AL12 by setting the values as shown in Figure B.6o and clicking the arrow button

12. Now the SPMLab software “TM Deflection” signal will show the Amplitude of the 2nd harmonic of the cantilever oscillation



IndexAAFM probe cartridge 50Align Laser 152Aligning Laser 96Alignment Knobs 62anodic oxidation 188Area scanning 69Auto Approach 143

BBias Line 189

CCable Connections 42Calibration 193, 199Calibration References 193cantilever 4Cantilever Tuning 115, 176Channel 130Channel Selection 100, 184chip carrier 52Closed Loop 86, 141Contact AFM principles 93Contact Imaging 93Contact Information iv

DDeflection Sensor 58, 62

EEFM Imaging 173Engage 86, 99, 127, 153

Ffeedback 4Feedback Loop 6, 16Feedback Signal 15

GGains 16

Hhigh gain 81

IIndentation 188Installing a Chip Carrier 49Integral Gain 16, 103, 143IV curves 82

LLaser Indicators 64Laser on/off 57Leveling 103LFM Imaging 105LFM Signal 107Lift Mode 79, 161Line scanning 71Loading a Sample 47low gain 81

MMFM 161, 173MFM Imaging 161Mode 161Motor Speed 66Motor Stage 97Motor stage 66Multimeter 87

NNanoPlot 88, 187Number of Data Points 10, 104

OOscilloscope 87Other Controls 91oxidation mode 188

PPan/Zoom 117, 165phase curve 121phase detection 161, 173phase setting 166Point Spectroscopy 81, 87Point Spectroscopy window 155Probe Position 87Probe positioning 78

IndexProbe Positioning Window 83, 158, 160Profile 100, 133Proportional Gain 4, 16, 103, 143

SScan angle 11Scan Parameters 102Scan Range 102Scan Rate 7, 11, 102Scan Size 7, 11Scanner 2, 44Scanning conditions 81Scanning Window 141, 158Select Frequency 120Set Frequency 166, 180Setpoint 5, 10, 14, 15, 104Signal Tracing 87Signal Tracing window 83Single Point Spectroscopy 3Space requirements 40Spectroscopy 149SPM 5spring tool 50Stage adjustments 56Stage Reset 66Start/Stop Frequency Sweep 165STM Cartridge 137STM Image 140, 148STM Tips 135System Configuration 60, 114

TTapping AFM 113These 11Tip Bias Voltage 184

VVeeco Contact Information iv

WWinTV32 53, 151

XX and Y offsets 11

ZZ piezo linearizer 157Z Position Bar 14zoom box 117

Documents

Veeco AFM DiInnova USER MANUAL-B (004-1005-000).pdf