Silicon nitride etching performance of CH2F2 plasma diluted with argon or krypton

Etching rates of silicon nitrides (SiN), SiO2, and poly-Si films for CH2F2 plasmas diluted with rare gases are presented by comparing the effects of flow rates of CH2F2 and dilution gases (Ar and Kr). The SiO2 etching rate was considered to be controlled by ion fluxes of the incident CHF2+ and CH2F+ under the conditions for the selective etching of SiO2 and SiN over poly-Si. Interestingly, the SiN etching rate was considerably affected by the dilution gas used. The SiN surface reaction was promoted by F-rich chemistry in the Ar-diluted CH2F2 plasma with a relatively high density of F atoms.