Developing a Fluorinated Greenhouse Gas Stack Testing Method Using FTIR
Gilliland, Tina; Laush, Curtis
(Texas Instruments, Inc. and IMACC)
Texas Instruments Incorporated (TI) is interested in identifying an alternative method to more accurately estimate Greenhouse Gas (GHG) emissions from their semiconductor fabrication operations(fabs) to reduce the cost burden of the final Mandatory Reporting Rule, Subpart I (40CFR98). In order to accomplishment this goal, TI proposes estimating emissions using a facility wide mass balance approach based on emissions characterization using familiar analytical equipment such as the Fourier Transform InfraRed mass spectrometer (FTIR) and production metrics. Historical data using FTIR at the end of line exhaust stacks indicated that many of the process greenhouse gas (GHG) concentrations were below typical FTIR detection limits of 50 parts per billion by volume (ppbv). IMACC, a company that specializes in designing and manufacture of FTIR monitoring systems for industry and government, understood the challenges of measuring these compounds at sub-ppbv levels and performed experiments in their lab with a modified FTIR to achieve lower detection limits. The primary objective of this study was to measure in the field exhaust stacks at a typical operating semiconductor fab to demonstrate the feasibility of measuring GHGs at sub-ppbv. IMACC, using their enhanced FTIR and approved EPA Methods 301 and 320, successfully measured stack level emissions at three TI fabs with detection limits in the parts per trillion by volume (pptv), thus demonstrating the feasibility at both 200mm and 300mm semiconductor fabs. The second objective of this study was to reasonably correlate the semiconductor fab operational parameters with measurements at the exhaust stack. The field data is currently being evaluated and the non-confidential information available will be shared for this presentation. Members of the semiconductor industry desire to use this stack testing methodology to develop facility wide emissions factors for each GHG so that semiconductor fab GHG emissions can be estimated in a more accurate and cost effective manner.