Selective vapor phase etching of SiGe versus Si by HCl

Abstract

Chemical vapor phase etching of SiGe versus Si by HCl was investigated using a single wafer reduced pressure CVD (RPCVD) system. The etch rate of SiGe layer was higher than that of Si and it is increasing with increasing Ge concentration, that means selectivity of etch rate of SiGe to Si is increasing with increasing Ge concentration. The etching process of Si seems to be anisotropic because etching of [110] direction was observed whereas the etching of [100] direction was negligible. Activation energy of etch rate of Si and SiGe with 10, 20 and 30% were estimated to ~ 2.1 eV (~ 48 kcal/mol). The combination of differential Si/SiGe growth, selective polycrystalline Si/SiGe etching and epitaxial SiGe etching in one process was demonstrated.