Selective etching of SiO2 relative to Si by plasma reactive sputter etching

Abstract

Plasma reactive sputter etching, sputter etching using Freon (CF4, C2F6, etc.) instead of argon as the etching gas, has been investigated. It has been found that there exists an etching reaction caused by energetic ions (CFn+ etc.) different from reactions found in conventional methods. Selective etching of SiO2 and Si3N4 on Si has been realized by enhancing the etching reaction with the effects of etching table materials (Teflon, carbon) and mixing gas (C2H4, CH4, etc.). Pattern transfer from mask to underlying substance, at least in selective SiO2 etching, can be performed uniformly without undercutting and with almost no lateral shift of pattern edges, with higher accuracy than in conventional plasma and sputter etching.