Whole Air Canister Sampling Coupled with Preconcentration GC/MS Analysis of Part-per-Trillion Levels of Trimethylsilanol in Semiconductor Cleanroom Air

Author(s): Jason S. Herrington
Restek Corporation

Published By: Analytical Chemistry

Issue: 85 (16)

Year of Publication: 2013

Link: http://pubs.acs.org/doi/abs/10.1021/ac401522p

Abstract: The costly damage airborne trimethylsilanol (TMS) exacts on optics in the semiconductor industry has resulted in the demand for accurate and reliable methods for measuring TMS at trace levels (i.e., parts per trillion, volume per volume of air [pptv] [ng/m3]). In this study I developed a whole air canister-based approach for field sampling trimethylsilanol in air, as well as a preconcentration gas chromatography/mass spectrometry laboratory method for analysis. The results demonstrate clean canister blanks (0.06 pptv [0.24 ng/m3], which is below the detection limit), excellent linearity (a calibration relative response factor relative standard deviation [RSD] of 9.8%) over a wide dynamic mass range (1–100 pptv), recovery/accuracy of 93%, a low selected ion monitoring method detection limit of 0.12 pptv (0.48 ng/m3), replicate precision of 6.8% RSD, and stability (84% recovery) out to four days of storage at room temperature. Samples collected at two silicon wafer fabrication facilities ranged from 10.0 to 9120 pptv TMS and appear to be associated with the use of hexamethyldisilazane priming agent. This method will enable semiconductor cleanroom managers to monitor and control for trace levels of trimethylsilanol.

Whole Air Canister Sampling and Preconcentration GC-MS Analysis for pptv Levels of Trimethylsilanol in Semiconductor Cleanroom Air

Author(s): Jason S. Herrington
Restek Corporation

Published By: Restek Corporation

Year of Publication: 2013

Link: http://www.restek.com/Technical-Resources/Technical-Library/Air-Sampling/env_EVAN1788-UNV

Abstract: The costly damage trimethylsilanol (TMS) in cleanrooms exacts on scanner lenses in the semiconductor industry has resulted in the demand for accurate and reliable methods for measuring TMS at trace levels (i.e., parts-per-trillion, volume-per-volume of air [pptv] [~ng/m3]. This study developed a whole air canister-based approach for field sampling trimethylsilanol in air, as well as a preconcentration gas chromatography–mass spectrometry (GC-MS) laboratory method for analysis. Results demonstrate clean canister blanks (0.06 pptv [0.24 ng/m3], which is below detection limit [BDL]); excellent linearity (a calibration relative response factor [RRF] relative standard deviation [RSD] of 9.8%) over a wide dynamic mass range (1.0 to 100 pptv); recovery/accuracy of 93%; a low selected ion monitoring (SIM) method detection limit (MDL) of 0.12 pptv (0.48 ng/m3); replicate precision of 6.8% RSD; and stability (84% recovery) out to four days of storage at room temperature. These performance levels should meet the demands of the semiconductor industry for monitoring trace levels of trimethylsilanol in cleanrooms.