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Proceedings Paper

Measurement of low molecular weight silicon AMC to protect UV optics in photo-lithography environments
Author(s): Jürgen M. Lobert; Charles M. Miller; Anatoly Grayfer; Anne M. Tivin
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Paper Abstract

A new analytical method for semiconductor-specific applications is presented for the accurate measurement of low molecular weight, silicon-containing, organic compounds TMS, HMDSO and D3. Low molecular weight / low boiling point silicon-containing compounds are not captured for extended periods of time by traditional chemical filters but have the same potential to degrade exposure tool optical surfaces as their high molecular weight counterparts. Likewise, we show that capturing these compounds on sample traps that are commonly used for organic AMC analysis does not work for various reasons. Using the analytical method described here, TMS, HMDSO and D3 can be measured artifact-free, with at least a 50:1 peak-to-noise ratio at the method detection limit, determined through the Hubaux-Vos method and satisfying a conservative 99% statistical confidence. Method detection limits for the compounds are 1-6 ppt in air. We present calibration curve, capacity, capture efficiency, break-through and repeatability data to demonstrate robustness of method. Seventy-one real-world samples from 26 projects taken in several fab environments show that TMS is found in concentrations 100 times higher than those of HMDSO and D3. All compounds are found in all environments in concentrations ranging from zero to 12 ppm, but most concentrations were below 50 ppb. All compounds are noticeably higher in litho-bays than in sub-fabs and we found all three compounds inside of two exposure tools, suggesting cleanroom and/or tool-internal contamination sources.

Paper Details

Date Published: 23 March 2009
PDF: 12 pages
Proc. SPIE 7272, Metrology, Inspection, and Process Control for Microlithography XXIII, 727222 (23 March 2009); doi: 10.1117/12.816277
Show Author Affiliations
Jürgen M. Lobert, Entegris, Inc. (United States)
Charles M. Miller, Entegris, Inc. (United States)
Anatoly Grayfer, Entegris, Inc. (United States)
Anne M. Tivin, Entegris, Inc. (United States)

Published in SPIE Proceedings Vol. 7272:
Metrology, Inspection, and Process Control for Microlithography XXIII
John A. Allgair; Christopher J. Raymond, Editor(s)

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