Patent ID: 7125787
Filing Date: 2006-10-24
Classification: H01L

Abstract:
1. A method of manufacturing an insulated gate semiconductor device, comprising: forming a first gate oxide film on a semiconductor substrate of a first conductivity type; forming a first silicon layer on the first gate oxide film; forming an oxidation protection film having a predetermined pattern on the first silicon layer; forming a field oxidation film and a second gate oxide film through selective oxidation by using the oxidation protection film as a mask, the second gate oxide film being in contact with the first gate oxide film; forming a second silicon layer covering the first silicon layer remaining after the selective oxidation, the second gate oxide film and the field oxidation film after removing the oxidation protection film; isolating a portion of the second silicon layer by etching so that the isolated portion of the second silicon layer covers at least part of the second gate oxide film and a portion of the remaining first silicon layer; and forming a source layer or a drain layer which is of a second conductivity type, wherein the formation of the field oxidation film and the second gate oxide film is always performed after the formation of the first silicon layer, and the formation of the second silicon layer is always performed after the formation of the field oxidation film and the second gate oxide film.