SEMICONDUCTOR SUBSTRATE AND FIELD EFFECT TRANSISTOR, AND MANUFACTURING METHOD THEREOF

摘要

PROBLEM TO BE SOLVED: To form a SiGe layer which has through dislocation density and low surface roughness on an SOI structure as to a semiconductor device and a field effect transistor, and a manufacturing method for them. SOLUTION: An SOI substrate 1 equipped with an insulating layer 1b on an Si substrate 1a and an Si layer 1c on the insulating layer is equipped with SiGe layers 2 and 3 on the Si layer of the SOI substrate, and the SiGe layer partially has a slanting composition area 2 whose Ge composition ratio is gradually increased toward the surface.