A Novel Etching Method of Single Crystalline A1₂o₃ Film on Si and Sapphire Using Si Ion Implantation

Abstract

A new etching method for a single crystalline ΑI₂O₃(100) film grown on Si(100) by LPCVD and a sapphire wafer is established for the first time using Si ion-implantation and buffered hydrofluoric acid (HF+H2O) chemical etchant to develop many applications of the SOI structure. Line and space patterns of resist were transferred to sharp A1₂O₃ and Si patterns. An etching of 0.12/μm-thick-Al₂O₃ films on Si substrates and sapphire wafers was observed very clearly. The etch rate is lOOÂ/min under implanted conditions of 80kV and 3×10¹⁵ cm^-2.The implanted ΑI₂O₃ surfaces are investigated by SIMS and XPS. The change from AI₂O₃ to Al₂O₃ SiO₂ (aluminosilicate), which can be easily etched HF+H₂O, is considered to be a main reason, though bonds broken by implantation are also effective for this etching.