AVS 45th International Symposium
    Partial Pressure Measurements and Process Control Topical Conference Friday Sessions
       Session PC-FrM

Paper PC-FrM6
In situ Measurement of Moisture Contamination in Reactive Process Atmospheres

Friday, November 6, 1998, 10:00 am, Room 317

Session: Process Monitoring and Control
Presenter: J.J.F. McAndrew, Air Liquide
Authors: J.J.F. McAndrew, Air Liquide
R.S. Inman, Air Liquide
D. Znamensky, Air Liquide
J.-M. Girard, Air Liquide, France
G. Goltz, France Telecom
J.-M. Flan, SGS-Thomson, France
Correspondent: Click to Email
In situ measurement of molecular contamination in semiconductor processing is important for (i) early detection of contamination events to avoid accidental misprocessing (ii) real-time control of purging procedures to improve tool utilization, and (iii) understanding of actual contamination levels in process atmospheres. In the present work the primary goal is to simplify chamber qualification and process more wafers between maintenance. Semiconductor processing applications use reactive atmospheres with which in situ monitoring equipment must be compatible. Achieving real benefits in a manufacturing environment requires a sensor which is user-friendly and reliable, even under demanding conditions. Absence of drift and reliability of calibration are also important. In order to simplify implementation, it is desirable to monitor as few species as necessary to obtain the desired information. Water vapor may be used as a general diagnostic of ambient contamination, because it is present in relatively high concentration in air and is often the most difficult species to eliminate from the process atmosphere. The implementation of Tunable Diode Laser Absorption Spectroscopy (TDLAS) for in situ monitoring of water vapor in a Rapid Thermal Processor (RTP) has been described previously.@footnote 1@ That work did not address compatibility with reactive atmospheres, as the RTP uses only nitrogen as process gas. Here, we will describe the implementation of TDLAS in aggressive environments, including application to silicon nitride CVD and other processes. Implementation of the TDLAS system in a CVD process poses significant challenges, as deposition of reaction products on the sensor optics must be carefully limited. In silicon nitride CVD, appropriate heating of the optics has been found to be critical. Water vapor levels measured during processing and their impact on process parameters will also be described, as will the use of real-time contamination measurement to improve tool-utilization by simplifying chamber qualification. @FootnoteText@ @footnote 1@J.J.F. McAndrew R. S. Inman, A. Haider and J. Brookshire, 44th International Symposium of the AVS (1997) Abstract Number: 1159: Program Number: MS+VT-ThA7 (submitted to JVST A)