PFC Stack Emissions Testing
(WaferTech, Camas WA)
The goal of this testing was to determine if stack testing could be used to replace recipe specific testing required in the federal reporting rule. During February of 2011, the SIA stack testing subcommittee developed the various stack testing options for testing emissions from electronic manufacturing Fabs. Various test methods were considered with the criteria determined to be 1-10 ppb detection level . This equated to Fab emission of 1,000 to 40,000 MT CO2 eq depending on the Fab’s exhaust rate. Our site used GM/MS method to determine the concentrations of PFC’s and collection the samples using Summa containers. This method requires one-two days of onsite sample collection by a local emission testing company. Our process PFC emissions are routed to five acid scrubber stacks. In April of 2011, we tested the five acid scrubbers simultaneously to reduce any variability of the site wide data. During the collection of the samples daily PFC gas usage data was collected and tier 2 emissions were compared to stack test results. The daily rate was also compared to the prior year’s usage rate to determine if the test was representative of the annual usage rate. The GC/MS analyst was done at a remote certified lab with additional QC procedures to validate the method. The testing included duplicate samples, blanks, ambient samples, and spiked samples. These samples are also part of a stability study. The laboratory results demonstrate that the samples are accurate, stable and reproducible. The process data indicates that the tests were done while the plant was operating a 90-110% of the annual PFC gas usage rate compared to the prior year. Part of the cost of the study was paid for by ISMI.