Patent ID: 7183172

Claim:
A method of forming an SOI semiconductor substrate comprising: forming a porous silicon layer on a support substrate; sequentially forming an epitaxial layer, a buffer insulating layer and a diffusion barrier layer on the porous silicon layer; forming a buried oxide layer on a handle substrate; after forming the diffusion barrier layer, contacting the diffusion barrier layer with the buried oxide layer to be bonded; etching the support substrate until the porous silicon layer is exposed; and etching the porous silicon layer until the epitaxial layer is exposed, wherein the diffusion barrier layer is formed of an insulating layer having a lower boron diffusion coefficient as compared with the buried oxide layer, wherein the buffer insulating layer is silicon oxide formed by thermal oxidation or CVD, wherein the buffer insulating layer alleviates stress due to a difference between thermal expansion coefficients of the diffusion barrier and epitaxial layers, and wherein the diffusion barrier layer is composed of either one of a silicon nitride layer or a silicon oxynitride layer.