Determination of Trace Anions in High-Purity Gases in Semiconductor Processes

Abstract

This study involves testing for trace quantities of anions in highpurity gases (N2, H2, O2, Ar, He, HCI, CO2, NH3, SiH4, PH 3, and AsH3) used in the electronics industry. A set of gas sampling devices is designed and constructed using membrane filtration (0.45 μm) in conjunction with solution absorption. In order to increase the detection sensitivity, the detection system was improved by using a large volume sampler (480 μL) instead of the conventional concentrator column. The ion chromatography method in this study is successful in determining F–, CI–, NO3–, HPO 4 2– , and SO 4 2– in 11 types of high-purity gases. This method is sensitive and accurate and meets the needs of anion-contamination control during the production of high-purity gases and very-large-scale integration processing.