Method for manufacturing an insulated-gate semiconductor element

摘要

An insulated-gate semiconductor element having a high breakdown voltage is provided. The surface of a silicon carbide substrate is etched to form a concave portion. A particle beam, for example an ion beam, is irradiated from above, and a defect layer is formed at least in a bottom surface of the concave portion. The substrate is heated in an oxidation atmosphere, and an oxide film is formed at least on a side surface and the bottom surface of the concave portion. A gate electrode is formed on the oxide film. The oxide film at the bottom surface is thicker than at the side surfaces, so that a high breakdown voltage can be ensured, even when the surface of the silicon carbide layer is a face with which a superior epitaxial layer can be attained, such as the (111) Si-face of beta -SiC or the (0001) Si-face of alpha -SiC. <IMAGE>