Selective oxidation for making relaxed silicon germanium on insulator structures

Abstract

Methods and devices are provided to fabricate semiconductor devices with, e.g., SiGe-on-insulator structures. For example, a method for fabricating a semiconductor device includes forming a crystalline buffer layer on a substrate, forming an epitaxial semiconductor layer on the crystalline buffer layer, patterning the epitaxial semiconductor layer to form a patterned epitaxial semiconductor layer, and oxidizing a surface region of the crystalline buffer layer selective to the patterned epitaxial semiconductor layer to convert the surface region of the crystalline buffer layer to an insulating layer. The insulating layer insulates the patterned epitaxial semiconductor layer from the crystalline buffer layer. In one example structure, the substrate is a silicon substrate, the crystalline buffer layer is formed of germanium, the epitaxial semiconductor layer is formed of silicon-germanium, and the insulating layer is formed of amorphous germanium-oxide.