mid infrared absorption spectroscopy system for plasma … · r. wilcox, 13. august 2009, san jose...

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


Content

Introduction

QCLAS Technology

Applications of the Q-MAC System

• Plasmas in Surface Treatment Industry

• Plasmas in Semiconductor Industry

• Q-MACS Multi Component


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


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


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


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


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 …


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


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


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


Product Portfolio

TO-3 Packaging of QCL in Q-MACS Applications

For robust handling in industrial environment


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


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



Change of the BCl3 signal in an industrial plasma process



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




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




• 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



Q-MACS Process fibre - 2008 edition (overall view)control unit - optical unit - process coupling unit with IR fibre



Q-MACS Process fibre - 2008 editionprocess coupling unit with IR fibre



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



Q-MACS Process Fibre – etch monitoring



Q-MACS Process Fibre with 2 QCL Heads



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



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]


Future Developments of Q-MACS Technology

Examples of optimized and compact Q-MAC Systems

miniature detectors


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

mid infrared absorption spectroscopy system for plasma … · r. wilcox, 13. august 2009, san jose...

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