Patent ID: 9337288
Filing Date: 2016-05-10
CPC Classification: H01L

Claim Text:
1. A method of manufacturing a MOS-type semiconductor device, comprising: an oxide film forming step of forming a first thermal oxide film on one principal surface of a drift layer of a first conductivity type and patterning the first thermal oxide film; a well region forming step of selectively implanting impurity ions of a second conductivity type by using the first thermal oxide film as a mask and performing a heat treatment to form a well region of the second conductivity type having a higher impurity concentration than the drift layer; a source region forming step of providing a resist film above a surface of the well region so as to be separated from the first thermal oxide film, implanting impurity ions of the first conductivity type by using the resist film and the first thermal oxide film as a mask, removing the resist film, and performing a heat treatment to form a source region of the first conductivity type having a higher impurity concentration than the well region; a second oxide film forming and removing step of removing the first thermal oxide film, and after removing the first thermal oxide film, forming a second thermal oxide film, and then removing the second thermal oxide film from at least a region over which a gate electrode will be formed; and a MOS gate forming step of forming a gate oxide film so as to cover surfaces of the source region, the well region, and the drift layer which are adjacent to each other and forming the gate electrode on a surface of the gate oxide film.