Method for forming soi substrate

Abstract

A method for forming SOI substrates including a SOI layer containing germanium and a strained silicon layer disposed on the SOI layer, comprises forming a relaxed silicon-germanium layer on a first silicon substrate using an epitaxial growth method, and forming a porous silicon-germanium layer thereon. A silicon-germanium epitaxial layer is formed on the porous silicon-germanium layer, an oxide layer is formed on a second silicon substrate, the second silicon substrate is bonded where the oxide layer is formed to the first silicon substrate where the silicon-germanium epitaxial layer is formed. Layers are removed to expose the silicon-germanium epitaxial layer and a strained silicon epitaxial layer is formed thereon. The porous silicon-germanium layer prevents lattice defects of the relaxed silicon-germanium layer from transferring to the silicon-germanium epitaxial layer. Therefore, it is possible to form the silicon-germanium layer and the strained silicon layer of the SOI layer without defects.