Method of forming a shallow trench isolation region in strained silicon layer and in an underlying on silicon - germanium layer

摘要

A process for forming a shallow trench isolation (STI), region in a strained silicon layer and in a top portion of an underlying, relaxed silicon-germanium layer, has been developed. The process features definition of a first opening in a silicon nitride stop layer via an anisotropic RIE procedure, using a photoresist shape as an etch mask. A following RIE procedure using HBr-Cl2-O2 as an etchant is next performed, defining a second opening, or a shallow trench shape opening in a strained silicon layer and in a top portion of the underlying relaxed silicon-germanium layer.