Anal. Chem. 2003, 75, 698-700
Improvement in Analysis of O2 in N2 by Using Ar Drift Gas in an Ion Mobility Spectrometer S. Dheandhanoo* and S. N. Ketkar
Air Products and Chemicals, Inc., 7201 Hamilton Boulevard, Allentown, Pennsylvania 18195
Ion mobility spectrometry (IMS) is capable of providing real-time analysis of several impurities in inert gases. Because of its poor peak resolution, the IMS is susceptible to peak interferences. Previous study has shown that the detection limit and accuracy of O2 measurement in N2 suffers from peak interference. In many applications, the interference can be avoided by selecting a proper drift gas. For N2 analysis, we have demonstrated that the peak interference of O2 can be eliminated by using Ar as a drift gas. The use of Ar changes the chemical reactions that occur inside the drift region and results in different product ions. The peaks of new product ions are wellseparated and do not coincide with the peak representing O2. Impurity specification in high-purity bulk gases used in semiconductor fabrication process has become more stringent as integrated circuits (ICs) become smaller. The 2001 edition of the International Technology Roadmap for Semiconductors (ITRS)1 suggests that impurities in N2 should be
