Method for manufacturing semiconductor substrate and semiconductor substrate

A method for manufacturing a semiconductor substrate by forming an insulator film and a semiconductor single crystal layer successively on a surface of a silicon single crystal substrate to manufacture a semiconductor substrate having the semiconductor single crystal layer on the insulator film, the method comprising at least the steps of:

• forming a silicon nitride film having an epitaxial relationship with the silicon single crystal substrate on the surface of the silicon single crystal substrate as the insulator film by subjecting the silicon single crystal substrate to a heat treatment under a nitrogen gas-containing atmosphere;
• and
• forming the semiconductor single crystal layer on the silicon nitride film by epitaxial growth.

A semiconductor substrate having an insulator film and a semiconductor single crystal layer on the insulator film on a surface of a silicon single crystal substrate, wherein

• the insulator film is a silicon nitride film having an epitaxial relationship with the silicon single crystal substrate and
• the semiconductor single crystal layer is an epitaxial growth layer.