Methods for manufacturing semiconductor substrates in which a semiconductor layer for forming semiconductor device therein is formed on a supporting substrate with an insulating film interposed between, with which in forming the semiconductor layer on a substrate on which a buried pattern structure has been formed it is possible to greatly increase the film thickness uniformity of the semiconductor layer and the film thickness controllability, particularly when the semiconductor layer is being formed as an extremely thin film. As a result, it is possible to achieve improved quality and characteristics of the semiconductor substrates and make possible the deployment of such semiconductor substrates to various uses.