Surface Wave Plasma Abatement of CHF3 and CF4 Containing Semiconductor Process Emissions

Abstract

Projected exponential growth in semiconductor device manufacture over the next few years demands technology to reduce the corresponding increase in etchants such as perfluorocompounds (PFCs), CHF3, and SF6 that would be emitted into the atmosphere. These compounds are a cause for concern because of their large global warming potentials relative to CO2 and of their long lifetimes in the atmosphere, often tens of thousands of years. We demonstrate that a plasma-based technology can yield effective (up to 99.9%) destruction and removal efficiencies (DREs) for CF4 and CHF3 present in etch recipes widely used in the semiconductor industry. Specifically, we report application of surface wave plasmas at 2.45 GHz for this purpose. Post-plasma effluent analysis included the determination of DREs and product distributions, simultaneously by gas-phase FTIR and QMS. Application of microwave powers from 500 to 1950 W were investigated and DREs for CF4 and CHF3 reported. Final product analysis indicated that PFC conversion was limited to low molecular weight gases such as CO2, CO, COF2, H2O, and HF. These investigations demonstrate that surface wave plasma destruction of the referenced PFCs at the output of semiconductor etch tools is a viable nonintrusive point of use abatement technology.