Selective SiN/SiO2 Etching by SF6/H2/Ar/He Plasma

This paper presents the experimental data about SiN and SiO2 etching by SF6/H-2/Ar/He plasma discharge. It has been shown that SiN etch rate increases if add small amount of He (less than 5 sccm) into the discharge. The SiO, etch rate does not depend on Ile content in the plasma discharge and is almost the constant. The possible role of helium appears in reactions with H, species. Namely, He or metastable He* increases rate of H-atoms production. It is known from the previous publications that H-atoms enhance SiN etching Thus, helium can help to selectively etch silicon nitride over silicon oxide.