Selective Chemical Wet Etching of Si_0.8Ge_0.2/Si Multilayer

Abstract

We investigate the effect of the ageing time and etching time on the etching rate of SiGe mixed etching solution, namely 1 vp HF (6%), 2 vp H₂O₂ (30%) and 3 vp CH₃COOH (99.8%). For this etching solution, we found that the etch rate of SiGe layer is saturated after the ageing time of 72 hours, and the selectivity of Si<SUB>0.8</SUB>Ge<SUB>0.2</SUB> layer and Si layer is 20:1 at ageing time of 72 hours. The collapse was appeared at the etching time of 9min with etching solution of after saturation ageing time.