AVS 46th International Symposium
    Manufacturing Science and Technology Group Monday Sessions
       Session MS-MoA

Paper MS-MoA5
Standardization of the Method to a Moisture Concentration in Hydrogen Chloride Gas with Diode Laser Absorption Spectrometry

Monday, October 25, 1999, 3:20 pm, Room 611

Session: Ultra-Clean Society and Contamination Free Manufacturing
Presenter: Y. Ishihara, UC Standardization Committee, Japan
Authors: Y. Ishihara, UC Standardization Committee, Japan
Y. Sakakibara, NTT Advance Technology Corporation, Japan
Y. Kunii, Kokusai Electric Co., Ltd., Japan
K. Hasumi, Hitachi Tokyo Electronics Co., Ltd., Japan
I. Matsuda, Showa Denko K.K., Japan
N. Miki, Ultraclean Technology Research Institute, Japan
A. Ohki, Oosaka Sanso Kogyo Ltd., Japan
Y. Shirai, Tohoku University, Japan
Correspondent: Click to Email
A standard method is proposed, using diode LASER absorption spectroscopy, to measure the moisture (H@sub 2@O) in hydrogen chloride (HCl) gas at concentrations between 100 ppb to 0.1%. This standard is laid down to measure trace H@sub 2@O in HCl at point of use. In this standard, HCl with H@sub 2@O of unknown concentration (sample gas) is introduced into a laser absorption spectrometer which is kept at reduced pressure. Measurement is performed in the range of 1370 nm to 1389 nm in wavelength, and the second-derivative absorption intensity of H@sub 2@O is calculated. Using the second-derivative absorption intensity and pre-defined calibration curve, the H@sub 2@O concentration is determined. The determination limit, which was defined as 3 times of the standard deviation of the second-derivative intensity, was found to be 100 ppb when a program for noise cancellation was employed. For verification of calibration curve, calibration curves which were prepared at different timings at different places by different people showed good agreement of over 95%. Moreover, it is proved that calibration curve of H@sub 2@O in HCl can be substituted by that of H@sub 2@O in N@sub 2@ which is corrected with a correction coefficient.