Abstract
A method was developed to measure total hydrocarbons (THCs) to 1 part-per-trillion (ppt) concentration levels using gas chromatography. This method was applied to measuring THCs in a front opening universal pod (FOUP) under static and purge conditions. XCDA® purge gas was used for this experiment. XCDA gas is clean dry air (CDA) purified with Aeronex® purification technology to remove moisture to less than 1 part-per-billion (ppb) and hydrocarbons, sulfur, and siloxane contaminants to less than 1ppt. The experiment reveals that a FOUP's environment contains ppb levels of THCs under static conditions and ppt concentration levels of THCs under purge conditions. This test demonstrates that ppt purity gas can be delivered to and maintained in a FOUP. Finally, a silicon wafer is exposed to a FOUP environment under static and purge conditions. Desorption studies show that hydrocarbon contamination on the wafer is reduced under purge conditions.
Published Version
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