mid infrared absorption spectroscopy system for plasma … · r. wilcox, 13. august 2009, san jose...
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1R. Wilcox, 13. August 2009, San Jose
Q-MACS Team
in cooperation with INP Greifswald
2009
www.neoplas-control.de
Mid Infrared Absorption Spectroscopy System for Plasma Monitoring
2R. Wilcox, 13. August 2009, San Jose
Content
Introduction
QCLAS Technology
Applications of the Q-MAC System
• Plasmas in Surface Treatment Industry
• Plasmas in Semiconductor Industry
• Q-MACS Multi Component
3R. Wilcox, 13. August 2009, San Jose
Q-MACS Technology
Quantum-Cascade-Measurement and Control System – Q-MACS®
problem: real-time and in-situ control of plasma processes and trace gas analysis with a detection limit up to ppt
idea: application of a new class of infrared lasers: quantum-cascade-laser (QCL)
result: development of compact and easy to use systems for industrial and scientific applications
Q-MACS: Quantum Cascade Laser Measuring and Control System
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Measuring Principle
Leff
Analysis
LaserI0 I
Plasma / Gasmolecules
Inte
nsity
Wavenumber ν
I0 IeffL)(n
0 e)(I)(I να−⋅ν=ν
governed by Lambert Beer‘s Law
n
Principle: Absorption of the laser beam by plasma / gas molecules Result: On-line concentration of molecules
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Why in the Mid IR?
many molecules ...- only detectable in the (3 ... 20) µm spectral range (MIR)- with higher absorption cross sections (compared to VIS, NIR, ...)
1.0
0.8
0.6
0.4
0.2
0.0
Tran
smitt
ance
56789103
23456789104 Wavenumber ν [cm-1]
12 3 4 5 6 7 8 9
102
Wavelength λ [µm]
CO2NO
NIR MIR
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Comparison of Methods
IR - TDLAS IR - QCLAS CRDS FT - IR
sensitivity(I0-I)/I0
☺ (10-3...10-5) ☺ (10-3...10-5) ☺ (10-3...10-5)
☺ (10-4...10-3) cm-1
(1...10) cm-1
s…ms
needs highlyreflective mirrors
mirrors selectedfor single
wavelength
(10-2...10-3)
selectivity∆ν
☺ (10-4...10-3) cm-1
☺ (10-3...10-2) cm-1 0.1 cm-1
tunability(10...100) cm-1 (1...10) cm-1 ☺ whole MIR
time resolution∆t
ms (... µs) ☺ ms...ns min...s
operation/detection
(20 - 130) KLN2 detectors
☺ near room T☺ TE detectors
☺ room TLN2
detectors
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Q-MACS Technology — wide spread applications
Plasma Industry /Exhaust Gas Treatment / Environmental Technology
Process Control in Deposition and Etching ReactorsSemiconductor IndustryCar IndustryMedicine TechniqueCombustion Fusion DevicesUF6 enrichment …
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Q-MACS Technology
Technology
• quantum cascade laser – absorption – spectrometer
• identifies gases and plasma species and quantifies their concentrations
• very low detection limits (up to ppt)
• enables in-situ measurements
• very high temporal resolution (real-time, ns – ms - s)
• works at room temperature
1 cm
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Product Portfolio
Product variants for customized high performance diagnostics
Q-MACS Basic
key component, laser head with
control- and supply unit
Q-MACS Process
high sensitive real-time gas and plasma
sensing
Q-MACS Trace compact
trace gas detection and environmental
monitoring
Q-MACS Process Fibre
measurement and control system for
plasma etch systems
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Product Portfolio
Q-MACS Basic
• key component for all Q-MAC Systems
• for operation with pulsed and cw QCLs
• laser head with control and supply unit for applications in spectroscopy
Q-MACS head
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Product Portfolio
TO-3 Packaging of QCL in Q-MACS Applications
For robust handling in industrial environment
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Product Portfolio
Q-MACS Multipass optics
• efficient solution to increase the effective absorption length
• include a robust and compact set of gold coated mirrors
• flange mounted for in-situ installation at plasma chambers
• allow a wide range of possible absorption lengths
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Applications of Q-MACS
Q-MACS Process with IR-fibre coupled to the industrial plasma reactor for surface treatment
detector unitplasma reactor
Q-MACS ProcessIR-fibre
beamincoupling
IR-fibre
plasma reactor
reactor-fibre-coupling module
Q-MACS head with fibre-coupling
detector-module
Scheme Photo at EltroPuls GmbH, Baesweiler, Germany
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Applications of Q-MACS
Change of the BCl3 signal in an industrial plasma process
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Applications of Q-MACS
Q-MACS Process Fibre - concept
• optical coupling of theradiation at the process chamber via IR fiber
• reflective elementsin-situ (mirror, wafer) for detecting via single view port
• optic board with multi channels for referencing the laser emission
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Applications of Q-MACS
Q-MACS Process Fibre
Development objectives
• monitoring of species concentration relevant for silicon plasma etch processes via Quantum Cascade Laser Measuring and Control System(Q-MACS)
• adaptation of Q-MACS for in-situ application at process tools with single access (one window)
• process control via IR laser absorption spectroscopy
• monitoring of the etch progress via online depth control measurements
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Applications of Q-MACS
Q-MACS Process Fibre
• realization of a tool for in-situ monitoring of silicon plasma etching
• development and design of a compact and integrable product
• process control with Q-MAC System possible
• enables strong improvements in process stability and reproducibility
at a HART III plasma etch system
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Applications of Q-MACS
Q-MACS Process fibre - 2008 edition (overall view)control unit - optical unit - process coupling unit with IR fibre
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Applications of Q-MACS
Q-MACS Process fibre - 2008 editionprocess coupling unit with IR fibre
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Applications of Q-MACS
Q-MACS Process Fibre - Dilution of SiF4 with Arp= 50 mTorr, SiF4 flow = 200 sccm
black numbers:% step size of Ar-MFC-FSRFSR: 400 sccm
red numbers:% change of Ar concentration
600 720 840 960 10800.4
0.5
0.6
0.7
0.8
10
10
105
55
5
10
10
8
8
73
33
4
8
8
SiF
4 co
ncen
tratio
n, 1
015cm
-3
time, s
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Applications of Q-MACS
Q-MACS Process Fibre – etch monitoring
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Applications of Q-MACS
Q-MACS Process Fibre with 2 QCL Heads
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Applications of Q-MACS
Active Controlling of Gas Mixture of N2, SiF4 und C4F6, p= 0.3mbar
15:00 15:30 16:00 16:30 17:00 17:30 18:00 18:300
5
10
15
0
50
100
150
SiF4 target 6 x1014cm-3
C4F6 target 4x 1014cm-3
conc
entra
tion,
1014
cm-3
time, mm:ss
N2 flow manuallyincreased / decreased
control increasesSiF4 flow
PID control gas
flow
, scc
m
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Applications of Q-MACS
Active Controlling of SiF4 Concentration in Plasma Reactor, p= 0.3 mbar
0 1 2 3 4 5 60.0
2.0
4.0
6.0
8.0
10.0
12.0
0
10
20
30
40
plasma offplasma on
SiF
4 con
cent
ratio
n [1
014cm
-3]
rel. time [min]
concentration target 5 x1014cm-3 gas flow
SiF
4 flow
[scc
m]
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Future Developments of Q-MACS Technology
Examples of optimized and compact Q-MAC Systems
miniature detectors
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Summary
Principle of QCLAS
Q-MACS Technology
Applications of the Q-MAC System
• Surface Treatment Industry – time resolved in-situ species monitoring
• Semiconductor Industry – process monitoring
• Q-MACS Multi Component – multiple species monitoring, MFC calibration
• CxHy, CO, CO2, NO, NO2, N2O, NH3, NF3, BCl3, B2H6, SiF4, C4F6, COCl2, PH3, H2O, O3, SO2, OH, HF, HCl, OCS, HCN, COF2, H2O2, SF6, SO3, HNO3, CH3CL, H2CO, CH3OH and many others