EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 1/14
SEM MERLIN Manual
Reservation Policy:
2 booking slots maximum per day and per person (i.e. 1h).
6 booking slots maximum per week and per person (i.e. 3h).
Reservation names must correspond to the operators
Contents:
I. System description
a. Overview
b. The GEMINI II column
c. Available detectors
II. Access conditions
III. Basic operations
a. Starting with the ZeissSmartSEM software
b. Loading – Unloading
c. Stage motions
d. Sample observation
e. Useful keyboard shortcuts
EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 2/14
I. System description
a. Overview
1. Electron optical column GEMINI II
2. Specimen chamber
3. Semi-automatic loadlock
4. Control monitors
5. Dual joystick
6. Control panel
The CMi SEM MERLIN is composed of a GEMINI II column, a process chamber with a 5-axes
motorized stage (X, Y, Z, Tilt and Rotation) and a semi-automatic airlock. The stage is eucentric,
which means that all rotation axes intersect the same point. The specimen surface is located at the
eucentric point, where the tilt axis meets the beam axis. This guarantees that the focus is maintained
when the specimen is tilted at a certain working distance.
Three different holders are available: mono samples, cleaved samples and full 4inch wafer.
1
2 3
4
5
6
EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 3/14
The SEM is controlled by the ZeissSmartSEM software operated via a graphical user interface. The
system is also fitted with a dual joystick for stage control and specimen navigation and with a main
keyboard control panel for direct access to 14 of the most frequently used functions on the SEM.
b. The GEMINI II column
The GEMINI II column is the area of the Field Emission SEM, where electrons are emitted,
accelerated, bundled, focused and deflected. Main characteristics of the GEMINI II optics are the so-
called beam booster and an objective lens that consists of a combined electrostatic/electromagnetic
lens doublet.
A Schottky field emitter serves as gun (1). Electrons are emitted from the heated filament while an
electrical field is excited by applying the extractor (Uext) voltage. To suppress unwanted thermoionic
emission from the shank of the Schottky field emitter, a suppressor voltage (Usup) is applied as well.
The emitted electrons are accelerated by the acceleration voltage (Ueht).
EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 4/14
The beam booster (Ub, booster voltage), which is always at a high potential when the acceleration
voltage is at most 20kV, is integrated directly after the anode. This guarantees that the energy of the
electrons in the entire beam path is always much higher than the set acceleration voltage. This
considerably reduces the sensitivity of the electron beam to magnetic stray fields and minimizes the
beam broadening.
Column mode Characteristics Beam path
High Resolution
High resolution
imaging
The upper condenser (1) has a low excitation which is varied in order to adjust the probe current in a limited range.
Electrons interaction effect is minimized
High spatial resolution is guaranteed
Probe current range is limited
Analyzer
Non-
conductive materials and
polymers imaging
The upper condenser (1) focuses the beam and creates a crossover above the ebeam-limiting anode aperture (2). The upper condenser is adjusted to modify the probe current. The lower condenser (3) is used for aperture matching of the objective lens (4) for optimum spatial resolution.
Whole probe current range is accessible
Depth of Field
High topography
imaging
The upper condenser (1) focuses the beam and creates a crossover above the ebeam-limiting anode aperture (2). The upper condenser is adjusted to modify the probe current. The lower condenser is operated at a higher excitation than in the two modes describes above. This results in a smaller aperture semi-angle. Thus, the depth of field is increased with a slightly reduced spatial resolution.
Provide a high depth of field
Useful to investigate high aspect ratio samples or to navigate on a tilted specimen
Fish-eye
Overall view of the sample
This mode enables you to view the entire 4inch wafer with electrons (EHT on). Useful for finding you sample or test patterns on the wafer
c. Available detectors
The interaction products most frequently used for generation of images in scanning electron
microscopy are secondary electrons (SEs) and backscattered electrons (BSEs). For that purpose,
three different detectors are fitted to the system.
Detectors Typical application
In-Lens (annular detector)
Surface structure
HE-SE2 (Everhart-Thornley detector)
Topography
EsB with filtering grid (in-column detector)
Pure material contrast
EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 5/14
The In-Lens detector is a high efficiency detector for high resolution SE imaging. It is located
above the objective lens and detects directly in the beam path.
The efficiency of the In-Lens detector is mainly determined by the electric field of the electrostatic
lens, which is decreasing exponentially with the distance. Thus, the working distance WD is one of
the most important factors affecting the signal-to-noise ratio of the In-Lens. As the tilt angle of the
specimen surface affects the emission angle of the electrons, you should avoid strong specimen
tilting.
The HE-SE2 detector is sensitive to SEs as well as BSEs.
Electrons moving to the detector are attracted by the collector and directed to the scintillator. The
collector voltage can be varied in the range between -1000V and +1000V. The collector voltage
generates an electrical field in front of the detector thus directing the low energy SEs towards the
scintillator. For all standard applications, the collector bias should be set at +300V.
Selecting a negative collector voltage generates a field deflecting the low energy SEs so that they
cannot reach the scintillator and do not contribute to the signal. Only high-energy BSEs contribute to
the image generation. This produces a so-called pseudo-backscattered inage, which shows
pronounced topography, but largely cancels surface properties (edge contrast).
The EsB detector is an Energy Selective Backscattered detector suitable for compositional
contrast. It is an annular in-column detector that is located above the In-Lens detector. It can
detect SEs and BSEs.
The SEs and BSEs generated at the impact point of the primary electron beam are intercepted by the
low electrical field of the column. These electrons are accelerated by the field of the electrostatic lens.
A small amount of SEs passes through the hole of the In-Lens detector and would be observed by the
EsB detector. To prevent detection of the SEs, a filtering grid is installed in front of the EsB detector.
By switching on the filtering grid voltage, the SEs will be rejected and only BSEs will be detected.
Below a landing energy of 1.5kV, the filtering grid has the additional function of selecting the desired
energy of BSEs. The operator can select the threshold energy of inelastically scattered BSEs to
enhance contrast and resolution.
EsB
In-Lens
Plasma
cleaner
EDX
HE-SE2
EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 6/14
II. Access conditions
1. The CMi SEM MERLIN is reserved to the regular CMI users.
2. It is exclusively reserved to the control of processes which have been done with the CMI
installation.
3. The maximal booking time per day is 1 hour (so 2 slots).
4. Saved pictures are available on STI network (EPFL local or VPN): "\\sti1files\cmi-
transfert\Z15-Zeiss-Merlin".
5. SEM training is focused on safe loading/unloading + main possibilities of the SmartSEM User
Interface + basic alignments procedures for quick and easy imaging. Images + detector
settings optimizations are not part of the training. Also, EDX analysis is only possible upon
additional training and only after SEM imaging is fully confirmed.
III. Basic operations
a- Starting with the ZeissSmartSEM software
First, the tool needs to be activated by logging onto CMi Zone15 computer with personal access rights.
On the SEM local computer, the Windows operating system is always open and running through
standard CMi session.
The EM Server, implementing the internal communication between software and hardware, is always
running too. It is sometimes minimized to a small element (icon) on the right side of the Windows task
bar.
Note: If the EM Sever was closed by the last User, Starting the ZeissSmartSEM software will first
reload the EM server and recover software/hardware communication.
EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 7/14
Double click on ZeissSmartSEM icon.
Alternatively, select Start/Programs/SmartSEM/SmartSEM User Interface. The EM Server Lon
On dialogue appears.
By logging, the SmartSEM user interface opens and is ready to operate the tool. By default, a TV
view inside the specimen chamber is shown.
Data zone Annotation bar
Status bar
Tool bar
SEM control tabs
EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 8/14
The data zone is a special and useful group of annotation objects which are used to display useful
parameters. If it is not open, select View/Data Zone/Show Data Zone from the menu.
Alternatively, type <Ctrl+D> to toggle the data zone
All icons from the toolbar run a specific action on the tool:
Specimen change via the loadlock
Left click Middle click
Live scanning Continuous averaging 2
Pixel averaging 3 Continuous averaging 4
Pixel averaging 6 Continuous averaging 6
Pixel averaging 9 Frame integration 5
Frame integration 7 Frame integration 9
Faster and slower scanning command
Freeze / Unfreeze command
Normal scanning command
Reduced area activation
Screen splitting to get two detectors viewing on the same window
Brightness and contrast adjustment (with mouse)
Chamber scope (TV view) activation
Toggle In-Lens / SE2 detectors
Magnification and focus adjustment (with mouse)
Save image to folder
EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 9/14
b- Loading
Press Exchange on the keyboard.
Follow and perform all instructions of the macro message before clicking OK.
Clicking OK will start pumping in the airlock and will open the gate.
The Vent button is used to ventilate the loadlock.
Be sure the holder is correctly loaded! Be sure to screw the rod on the holder!
EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 10/14
Close the door and click OK on the macro message for the pumping to start. When correct vacuum is reached, the gate will automatically open.
Check from the window when the gate is open. The light inside the chamber is automatically
switched on. Load the sample onto the stage and retract the rod all the way out. When loading, visually check from the window what you are doing!
Be sure the holder is steady on the stage and that it doesn't move when the rod is turned
counterclockwise and then retracted.
Click OK on the previous macro message and click Resume on the keyboard to close the gate.
Here, there is no need to ventilate the airlock: just click OK on this message.
Click OK to finish the loading sequence and to proceed with SEM imaging.
EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 11/14
c- Unloading
Press Exchange on the keyboard.
Click OK on the macro message (there is no need to ventilate the airlock now).
Clicking OK will start pumping in the airlock and will open the gate.
Check from the window when the gate is open. The light inside the chamber is automatically
switched on. Unload the sample from the stage and retract the rod all the way out.
When unloading, visually check from the window what you are doing!
Be sure the holder is steady in the airlock with the rod fully retracted.
Click OK on the previous macro message and click Resume on the keyboard to close the gate. Follow instructions before clicking OK on the following message.
EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 12/14
The Vent button is used to ventilate the loadlock.
Unload the sample.
Close the door and click Store on the airlock for the pumping to start. Validate the previous message by clicking OK.
EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 13/14
Click OK to finish the unloading sequence.
d- Stage settings and motions
The Stage Navigation window can be used to initiate XY movement of the stage by double-clicking
on the sample holder top view. Be sure to select the correct holder from the list and to adjust the zoom
view sliding bar to your needs. All five axes coordinates are reported in this window in order to save
specific positioning on the sample if needed.
The STOP button on the Stage Navigation window or the Break button on the dual joystick can be
clicked at any time to quickly stop any engaged motion of the stage.
Finding your way on the sample is mainly done by the use of the dual joystick panel, where all five
axes can be actuated.
e- Sample observation
The following table may help to find the required settings for your application:
Detector EHT Typical
WD Detector settings Remarks
In-Lens
3kV – 20 kV 3 – 6mm
None
Avoid strong specimen
tilting.
Surface structure
100V – 3kV 2 – 3mm
100V Max 4mm
HE-SE2
1kV – 30kV Min. 4mm Collector bias adjustable from -
1000V to +1000V.
Standard applications: +300V
None.
Topography
1kV – 5kV 4 – 6mm
5kV – 30kV Min. 6mm
Left joystick (Z and T) has to be
used with great care: a risk of
damaging the tool and/or the
specimen is present if hitting the
objective lens while driving the
stage. Watch the moving stage
in TV mode.
EPFL Center of MicroNanoTechnology SEM MERLIN Users Manual
November, 2013 14/14
Pseudo BSE image: -1000V to 0V
EsB
1kV – 5kV Max. 4mm EsB grid adjustable from 0V to
+1500V.
Value depends on type of
electrons to be detected (approx.):
<800V : SE +BSE
>800V: BSE
Avoid strong specimen
tilting.
Materials contrast 100V – 1kV 1 – 2mm
f- Useful keyboard shortcuts
Ctrl + d : display/hide data zone
+ (numerical keyboard) : increase the scanning rate - (numerical keyboard) : decrease the scanning rate
tab : fine/coarse mode
Ctrl + tab : center the sample when click on the picture
Ctrl + shift + tab : drag a rectangle on the picture and the system will automatically zoom in and center the sample into it
Ctrl + A : annotation tools
Please, avoid using the arrow keys at the edges of
the sliding bar when selecting column current! Use
either the slide bar, or type the desired valued in
directly.