Analysis of Gas Phase Metallic Impurities in Hydrolysable Gases
Publication Date: 2005-Sep-15
The IP.com Prior Art Database
The current practice of sampling for metallic impurities in hydrolysable gases is to hydrolyze the gas and analyze the hydrolysis solution using either ICPMS or ICPOES. This implicitly assumes that all the volatile metallic species in the sample gas will dissolve in the hydrolysis solution. Impurities that do not dissolve in the hydrolysis solution can not be detected. The semiconductor industry has stringent requirements for metallic impurities in gases. The semiconductor process is susceptible to all gas phase impurities, whether they can be dissolved in hydrolysis solution or not. For the case of ammonia there are reports that the industry can detect elemental impurities like S, Si, and Ge in their films although the analysis of hydrolysis solution of the gas fails to detect these impurities.
One can couple the hydrolysis apparatus to the ICPMS or ICPOES used to analyze for trace metallic impurities. The sample gas will be mixed with a stream of particle filtered argon. The metallic impurities that do not dissolve in the hydrolysis solution will be carried by the stream of argon into the plasma of an ICPMS or ICPOES. The gas phase metallic impurities will be atomized and ionized in the plasma and be subsequently detected.