Global warming gas emission during plasma cleaning process of silicon nitride using c-C4F8O/O2 chemistry with additive Ar and N2

Abstract

In this work, the cyclic perfluorinated ether (c-C4F8O) with very high destructive removal efficiencies (DREs) was used as an alternative process gas for cleaning of the silicon nitride chemical vapor deposition chamber. Direct plasma cleaning of silicon nitrides in a capacitively coupled plasma mode using the gas mixtures of c-C4F8O/O2, c-C4F8O/O2+Ar, and c-C4F8O/O2+N2 was investigated in order to evaluate the effects of additive gases (Ar and N2) on the global warming. Emitted net volumes of perfluorocompounds during cleaning of silicon nitride were quantitatively measured by Fourier transform-infrared spectroscopy. The effects of additive Ar and N2 on the DRE and the million metric tons of carbon equivalent (MMTCE) values were evaluated from the volumetric emission of effluents. MMTCE value for the optimized c-C4F8O/O2 cleaning was decreased by ≅64% compared to that of the C2F6/O2 chemistry as a result of decreased emission of CF4. During the cleaning process using c-C4F8O/O2 gas mixtures with additive Ar and N2, the DRE value as high as ≅98% was obtained and MMTCE values were reduced by ≅78% and ≅81% compared to those of C2F6/O2 cleaning, respectively, as a combined result of the decreased CF4 emission and increased cleaning rate.