Reducing GHG Emissions from Heat Transfer Fluids
Subpart I of 40CFR part 98 requires semiconductor fabs to file annual reports of greenhouse gas emissions to U.S. EPA. New Global Warming Potential (GWP100) numbers published by EPA have made fluorinated heat transfer fluids (F-HTFs) a much more significant piece of total fab emissions. In 2013, F-HTFs were 0.1% of total 300mm fab emissions while in 2014, with the GWP100 values assigned, they have risen to 29% of total 300mm emissions. This large reported increase in emissions can cause challenges in meeting greenhouse gas permit limits as well as increase the total GHG emissions that companies are reporting to the public. As regulatory and public attention on greenhouse gases increases, the issue is likely to become of greater importance to the semiconductor industry. This paper will look at options for reducing F-GHG emissions from heat transfer fluids including chemical substitution, equipment replacement or repair, and other emissions reductions options. These methods can result in significant emissions reductions and can be implemented with no capital expenditure and most often no or only slight changes to the process. For example swapping low boiling point F-HTFs (3Ms FC-3283 and Solvay’s HT110, HT135) to high boilers F-HTFs ( 3Ms FC-40, Solvay’s HT170, HT200) result in reductions in both emissions and in costs. This substitution has been shown to be transparent to the process, and for many process steps provides a ready means of reducing emissions. After many years of GHG reductions focused on fluorinated gases, the fluorinated heat transfer fluids are among the best remaining options for making additional reductions.