Mass spectrometric study of SF6-N2 plasma during etching of silicon and tungsten

Abstract

The reaction products in the SF6-N2 mixture rf plasma during reactive ion etching of Si and W have been measured by a mass spectrometric method. Two kinds of cathode materials were used in this work; they were stainless steel for the Si etching, and SiO2 for the W etching. The main products detected in the etching experiments of Si and W included SF4, SF2, SO2, SOF2, SOF4, SO2F2, NSF, NF3, N2F4, NxSy, NO2, and SiF4. In the W etching with the SiO2 cathode, additional S2F2, N2O, and WF6 molecules were also obtained. The formation reactions about the novel NSF compound and the sulfur oxyfuorides were discussed.