SEMICONDUCTOR SUBSTRATE, SEMICONDUCTOR SUBSTRATE MANUFACTURING METHOD AND COMPOSITE SUBSTRATE MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To reduce surface roughness of a group IV semiconductor crystal layer formed on a semiconductor crystal layer formation substrate of a group III-V compound semiconductor via a sacrificial layer to a degree necessary for transfer.SOLUTION: A semiconductor substrate in which a semiconductor crystal layer formation substrate, a sacrificial layer, an intermediate layer and a semiconductor crystal layer are located in the order of the semiconductor crystal layer formation substrate, the sacrificial layer, the intermediate layer and the semiconductor crystal layer, in which the semiconductor crystal layer formation substrate is composed of a group III-V compound semiconductor crystal, and the sacrificial layer is obtained by etching by an etchant for etching the sacrificial layer at an etching rate larger than that in the case where the semiconductor crystal layer is etched, and the intermediate layer has decreased surface roughness of the semiconductor crystal layer in comparison with the case where the semiconductor crystal layer is directly formed on the sacrificial layer, and the semiconductor crystal layer is composed of a group IV semiconductor crystal.