Advanced Process Monitoring and Control: Stable and Repeatable Plasma-based Deposition Processes

8/12/2019 Advanced Process Monitoring and Control: Stable and Repeatable Plasma-based Deposition Processes

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1Martynas Audronis and 2Mike Hou

1Nova Fabrica Ltd.2

Beijing Ailan Technology Ltd.

12014-07-16ThinFilms2014, Chongqing. CONFIDENTIAL. DO NOT

DISTRUBUTE.

BOOTH #2


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SME based in Lithuania (NorthEU).

Vision: increasing efficiency andeconomy of thin film production

plants.

Mission: supply effectiveprocess components andtechnology solutions at anaffordable cost.

Worldwide presence:comprehensive sales network inall major industrial countries:P.R.C, Taiwan, S. Korea, Japan &EU.

22014-07-16 ThinFilms2014, Chongqing. CONFIDENTIAL. DO NOT DISTRUBUTE.


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2014-07-16 ThinFilms2014, Chongqing. CONFIDENTIAL. DO NOT DISTRUBUTE. 3


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Image courtesy of Mustang Vacuum Inc.Source: www.reactive-sputtering.info

Image courtesy of Leybold Optics GmbH. Source: www.reactive-sputtering.info

In-line coater

Roll-to-roll coater

Image courtesy of Kolzer Srl. Source: www.reactive-sputtering.info

Box coater


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MFC


FloTron

Reactivegas control

Real time optical monitoring

OptaTron

Power Supply

EnerPulse Duo

1

2

3

4

5

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1) Stem from the need to meet product (coating, surface treatment)specifications and2) Reduce the cost of ownership of equipment.



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1. Process stability

Stable operation with no or little deviation from anygiven set-point. (e.g. within 1% or better)

2. Process reproducibility

Run-to-run,

Batch-to-batch.



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PRODUCTION

Dictated by stringent

product specificationrequirements, e.g.

Optical: T%, R%, , color

Electrical: resistivity and

conductivity, Physical thickness,

Coating uniformity

Large area

R&D

Dictated by the need to carryout well controlled

experiments, tests andproduce reliable data.

Chemical composition,

Precisely controlled gradients ormulti-layers,

Physical, optical, electrical, etc.properties,

Crystallographic structure,

etc.



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Encountered often across a wide range of PVD and PECVD processes


Stable, but not desired

Unstable,desired states


10/39102014-07-16 ThinFilms2014, Chongqing. CONFIDENTIAL. DO NOT DISTRUBUTE.

Process instability can occur as a result of

1. Physical or chemical process nature,

2. Environment or hardware related events.


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1. Process specific

Fast transition phenomena in reactive magnetron sputtering

2. Hardware specific

Moving plasma (FFE cathodes, Vacuum Arc)

Pulsed plasma (HIPIMS) Target erosion (Sputtering, Vacuum arc)

3. Drifts (short and long term)

Environmental changes in the process chamber Temperature Partial pressure of gases

4. Disturbances Moving substrates Substrate outgassing Entrance (gate) valve open/close (sudden pressure change) Arcing (magnetron sputtering)

5. Process scale Gas distribution non-uniformity


Transition phenomena - target poisoning

during Reactive Sputtering (after B. Sproul).

Plasma shifts due to target erosion

Plasma is moving due to rotating

magnets


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Production

Reject,

Lost time,

Exhausting process development,

Low production team morale,

Low customer satisfaction.

R&D Lost time,

Difficult to interpret data,

Unreliable, unrepeatable data.



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A cost effective and easy to deploy solution to many process issues- denotes cost saving features


Put a finger on your process issues with FloTron

Stable,

long term


14/392014-07-16 ThinFilms2014, Chongqing. CONFIDENTIAL. DO NOT DISTRUBUTE. 14

Channel 1 (Algo1)Optical or Voltage input 1

Optical or Voltage input 2

Optical or Voltage input 3 Channel 2 (Algo2)

Optical or Voltage input nChannel n (Alg0 n)

Actuator output 1

Actuator output 2

Actuator output n

(a) SENSOR ::: (b) CONTROL ALGO ::: (c) ACTUATOR

Number and type of optical inputs is flexible and dependsFloTron size and application.

Process A

Process B


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(a) SENSOR INPUTS ::: (b) CONTROL ALGO ::: (c) ACTUATOR OUTPUTS

3, 5 & 9 channel standard versions


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INPUTS 4 analog voltage inputs (BNC, 0-

10V),

2 PMT-based optical inputs,

1 CCD spectrometer-based optical

inputs,

OUTPUTS 5 or 9 actuator (e.g. MFC) outputs.

A more flexible system than eitherPMT or CCD spectrometer -basedones.

2 P.E.M. technologies in one system


PMTs (+ filters)

Spectrometer


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FEEDBACK-BASEDCONTROL

Process stability

Process-to-process reproducibility

as required for manufacturing andcontrolled experimenting

ALGORITHMS (proprietary) PID

(proprietary)PDF

Other algorithms


The concept of closed-loop controlled system


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1. Magnetron sputtering FFE

HIPIMS

4. Magnetron plasmasource


2. Plasma assistedEB evaporation

3. Vacuum Arc

5. PECVD

All 3 shown exhibit different challenges in terms of process monitoring & control


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New HIPIMS power supply technologies ->complex pulse patterns.

Intelligent HIPIMS plasma discharge monitoring

Provides excellent signal for a wide range ofHIPIMS pulse frequencies

will deal comfortably with pulses coming in atirregular intervals.

The signal provided by the NF HIPIMS PEM sensoris straight forward to interpret and convenient touse.

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Conventional HIPIMS voltage/current pulse and acorresponding light burst.

After Audronis et. al 2010 SCT paper.

Schematic of HIPIMS exhibit multiple pulses

V

HIPIMS discharge. Source: inplas.de

2014-05-26 Nova Fabrica Ltd. CONFIDENTIAL. DO NOT DISTRIBUTE.


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1. Reactive Magnetron Sputtering --- control

e.g. large area Dual Magnetron MF AC of SiO2, Al2O3, TiO2, Nb2O5, AZO,ITO,

e.g. precision optical coating deposition: HfO2, ZrO2, SiO2, Nb2O5, mixedoxides,

e.g. functional coating deposition: V2O5, WO3, MgO2, Cr-O-N, Ti-O-N, etc.

2. Plasma/Ion treatments --- control, monitoring e.g. magnetron based reactive plasma treatment process control and

monitoring,

e.g. Linear Ion Source discharge stabilisation and gas control.

3. Plasma Enhanced CVD --- monitoring, control

Process monitoring & control, QA

4. Reactive EB evaporation --- control, monitoring1. Reactive gas p.p. CrN, TiN, AlCrN, TiAlN -- gas flow control

2. deposition rate -- EB gun power supply control

5. End-point detection (OES-based) --- control, monitoring

6. Plasma OES diagnostics, fault finding, optimisation, etc.

Plasma parameters evaluation, insights into plasma characteristics.



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1. High accuracy process control providing required levels of stability and process-to-processrepeatability,

Reactive Magnetron Sputtering (RMS).

2. Accurate process and plasma monitoring,

PAPVD (magnetron sputtering, EB evaporation), PECVD, ...

3. Increase production rate,

1. 2-3 times typical for most materials in reactive sputtering.

4. Improve plant economy,

1. Sputter target lifetime -> less frequent target change, more coating produced from the same targetvolume (e.g. Si ...),

2. Cheaper and/or more less fragile sputter targets can be used,

3. Return of Investment (RoI) on a FloTron system is typically < 5 weeks in RS based production plant.

5. Improve coating uniformity (large area coating),

6. Improve coating physical properties(process set-point),

7. Help reduce defects(e.g. from arcing).212014-05-26 Nova Fabrica Ltd. CONFIDENTIAL. DO NOT DISTRIBUTE.


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1. Accurate process characterisation,

explore/identify process window.

2. High accuracy process control at any set-point within a processwindow,

3. Real-time process and plasma monitoring,

4. Plasma OES studies

Electron temperature, electron density, particle densities, real-time monitoring

5. Fine tune (optimise) coating chemical composition

6. Fine tune (optimise) plasma treatments

7. Record (log) all process and plasma OES data for analysis



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SENSORS



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1. Sputtering Target Voltage(plasma discharge impedance),

2. Plasma Emission Monitoring (P.E.M.),a) Direct (monitors the sputter cathode),

b) Indirect (monitors a remote plasma source),

3. Partial pressure (p.p.) of reactive gas.



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Sputtering Target Voltage

Invented in 1978 (36 years ago) J. Chapin [Applied Films Lab (US), US4166784, 1978]

Advantages

Inexpensive

Disadvantages Not suitable for multi-zone monitoring,

Works well for some materials (Al, Si) only,

Sputtering flux composition is unknown.

New development Harmonic analysis (B. Szyska & N. Malkomes, US6797128,

EP1232293 cover CH, GB, DE, FR, US)

Can cover wider range of materials and reduce long term drifts

Could be made available in FloTron

252014-07-16 ThinFilms2014, Chongqing. CONFIDENTIAL. DO NOT DISTRUBUTE.FloTron X system with 4voltage inputs

Pulse-DC power supply with ananalog voltage output


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Plasma Emission Monitoring (P.E.M.)

an OES technique [Von Ardenne (DE) 1982, Bell Labs (US) 1981]

Single wavelength PMT + narrow-band-pass filter

Broadband/multiple wavelength CCD/CMOS Spectrometer

OES/P.E.M. advantages High speed, Excellent signal,

Wide process window,

Sensitivity, Suitable for large area multi-zone processing, Low cost.

Disadvantages Prone to disturbances and drifts due to moving substrate, target erosion, etc.


FloTron X3 system with 1

spectrometer input

FloTron L system with 5

optical inputs


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Monitoring

1 wavelength permonitoring point

Multiple point PEM(M-PEM) [only]

Or M-PEM combinedw Voltage Control Dual-sensor mode

Gas control Master/Slave setup,

1+ Master actuatorsw Slave actuators.



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Robust design and low cost makeFloTron S, M & L systems a preferredprocesses controller in large area massproduction lines where monitoring onewavelength is enough.

a typical examples are reactive SiO2,Nb2O5 and TiO2,

the photograph on the right shows aFloTron L system controlling 3-zonelarge area reactive SiO2 sputteringprocesses in a vertical in-line coatingsystem.

Rugged enclosure design makesFloTron suitable for less than idealenvironments.

2014-05-26 Nova Fabrica Ltd. CONFIDENTIAL. DO NOT DISTRIBUTE. 28


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A ration between two OES emissions (e.g. A*/B*) inone monitoring pointcan be used advantageously forprocess control

e.g. Ti*

/Ar*

, Mo*

/Ar*

, etc. -- metal over Ar, e.g. In*/O*, V*/O* -- metal over reactive gas.

Benefits

1. Cancelation or minimization of long term process drifts(e.g. due to target erosion),

2. More precise thin film stoichiometry(i.e. chemicalcomposition) and property control.



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4 (max) analog voltage inputs (BNC, 0-10V).

3, 5 or 9 actuator (e.g. MFC) outputs.

Multiple optical inputs (SMA905) available

up to 8 CCD spectrometer channels can be added onrequest.

UV-VIS-NIR CCD spectrometer; detectorrange

A) 180 1040 nm.

B) 200 850 nm.

10-20 ms integration time typical for mostsputtering plasmas, even on 3 or 4cathodes.

2014-05-26 Nova Fabrica Ltd. CONFIDENTIAL. DO NOT DISTRIBUTE. 30


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Monitoring

Real-time spectramonitoring

Multiple species (max 5)

per point Multiple point PEM (M-

PEM)

M-PEM combined wVoltage Control Dual-sensor mode

Gas control

Master/Slave setup,

1+ Master actuators wSlave actuators.



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High signal resolution- 16 bit, 0-65k counts,thus very high processsensitivity.

Select plasma emissionsfor monitoring and control

Standard spectralresolution:1 6 nm (customer choice& depends on application)

Easy wavelength andbandwidth selection forprocess monitoring andcontrol.

Spectrometer calibrationconstants


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Multiple species monitoredin a single channel window

Process control information

Flexible adjustment of s/div


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Partial pressure of reactive gas

Mass spectrometer [Bill Sproul, 1983] Good performance,

Too big , complicated and expensive.

Loxygen sensor

Detects O2 only

Slow, needs constant air reference, heating,external power source and electronics,

Difficult to locate,

Poor Process Window resolution,

Works with some materials and processparameters only

Surface & Coatings Technology 206 (2012) 49304939

Surface & Coatings Technology 204 (2010) 21592164

Some designs can lead to limited life time

Reliability issues and field failures



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Very highdeposition rate,

Very tightprocess control,

Enhancedopticalproperties.


Vacuum 107 (2014) 159-163


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ACTUATORS :: MFC [gas flow], Power supply, [discharge power]



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MicroFlo Features & Benefits Flow Range: up to 1000 SCCM

Linearity Error: 0.05% FS

Repeatability: 0.15% FS

Response Time: 40ms (analog)

Economy solution

540.00 EUR /piece* * - Terms and Conditions apply.


Pneucleus MFCs


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1. Adequately designed process control can effectivelyeliminate or minimise process instabilities

Short and long term stability

Process reproducibility

2. The state-of-the-art hardware and software provide

convenience,

rapid and easy implementation,

all at a very affordable cost.



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www.novafabrica.biz

[email protected] #2

Documents

Advanced Process Monitoring and Control: Stable and Repeatable Plasma-based Deposition Processes