Patent ID: 7198997

Claim:
A method for producing a semiconductor substrate in which a SiGe layer is formed on a Si substrate, said method comprising: repeating, a plurality of times, a process of epitaxially growing a SiGe gradient composition layer of which a Ge composition ratio is gradually increased from a Ge composition ratio of a base material and a process of epitaxially growing a SiGe constant-composition layer on said gradient composition layer at a final Ge composition ratio of said gradient composition layer, thereby depositing a SiGe layer of which a Ge composition ratio changes in a film deposition direction, in a step-like manner with a gradient; performing heat treatment at a temperature exceeding a temperature of said epitaxial growth either during or after formation of said SiGe layer; and polishing to remove irregularities on a surface of said SiGe layer which arise in said heat treatment after formation of said SiGe layer.