ICP-MS: A Universally Sensitive GC Detection Method for Specialty and Electronic Gas Analysis

摘要

Inductively coupled plasma-mass spectrometry has been investigated as a detector for gas chromatography and applied to analysis of trace impurities in specialty and electronic gases. Several key attributes, including high sensitivity, near-universal nature, ease of interfacing to gas chromatography, tolerance to matrix gases, and use of wet-plasma conditions to facilitate indirect calibration for a gas species for which a gas standard is unavailable, are discussed. Examples such as sulfur speciation in hydrocarbon gases at low part-per-billion levels demonstrate its use for specialty gas analysis. A more detailed case study is given on detection of trace impurities in arsine, including silane, carbonyl sulfide, hydrogen sulfide, germane, and hydrogen selenide. Under optimized conditions, detection of germane is possible down to 5 ppt. As microelectronic devices become more complex and the features shrink, there has been increased demand for higher purity process gases. Some impurities, even if present at trace levels, can become incorporated into deposited layers and affect device performance significantly. Similar purity levels are required in other industrial specialty gas applications, such as for polymer manufacture, where trace impurities in monomer raw materials can affect catalyst activity significantly. This need to measure impurities at parts-per-billion and even parts-per-trillion levels has driven the development and use of highly sensitive and selective instrumental methods such as gas chromatography with inductively coupled plasma-mass spectrometry (GC-ICP-MS) and atomic emission detection (GC-AED).