Plasmaless dry etching of silicon with fluorine-containing compounds

Abstract

Silicon is rapidly etched by the gas-phase halogen fluorides ClF3, BrF3, BrF5, and IF5, in analogy to XeF2 etching silicon. Nearly complete selectivity over SiO2 is achieved in all cases. By contrast, ClF and Groups III and V fluorides such as NF3, BF3, PF3, and PF5 do not spontaneously etch either Si or SiO2 under the same experimental conditions. These relatively inexpensive interhalogens can be applied to pattern silicon and more generally to remove silicon or polysilicon layers without a plasma. Low-temperature plasmaless gasification of substrates by these fluorine-containing interhalogens is an economically attractive alternative to fluorine-based plasma etching.