The performance of two purification media in their removal of impurities from inert gases

Ultra-high-purity (UHP) inert gases such as N/sub 2/ and Ar are utilized in the semiconductor industry as purge and carrier gases for IC manufacturing processes. High quality product production is extremely dependent on process gas purity at the point-of-use (POU). Removal of impurities such as moisture, O/sub 2/, CO/sub 2/, and CO is highly critical at the POU due to the detrimental effects of these chemicals on the final product. The ramifications of a poorly purified gas are particle generation due to corrosion from moisture reacting with specialty gases and poor film growth due to the impregnation of impurities such as O/sub 2/ in film growth processes. There are a variety of POU purifiers that remove impurities based on different chemistries. With one type of purifier based on metallized Ni pellets, impurities are removed from the gas via multiple chemical pathways, e.g. chemisorption, oxidative and absorption processes. Another purification medium utilizes reactive micro matrices (RMMs), which remove impurities based strictly on chemisorption. In this paper, experimental results from evaluating these two purifiers are presented. Overall purifier performance and cleanliness were determined by analysis of downstream cleanliness using APIMS and particle shed testing. Also, safety aspects of accidental exposure of these purifiers to compressed air are examined. In general, results show the RMM-based purifier performed better overall. Initial installation of the RMM-based purifier showed an initial moisture spike four times lower than the Ni-based purifier. The Ni purifier also released undesirable nickel carbonyls under CO removal.