Patent ID: 8367536

Claim:
A method for manufacturing a silicon carbide semiconductor device including a silicon carbide drift layer of a first conductivity type positioned on a main surface of a silicon carbide substrate, a base region of a second conductivity type positioned in an upper layer part of said silicon carbide drift layer, a source region of the second conductivity type positioned in a surface of said base region, and a gate electrode positioned above said source region, said base region and said silicon carbide drift layer through a gate insulating film, in which an outer edge of said source region is positioned on an inner side than an outer edge of said base region, and a region of said base region positioned outside of the outer edge of said source region and positioned directly below said gate electrode corresponds to a channel region, the method comprising the steps of: (a) forming, on said silicon carbide drift layer, a first ion implantation mask and a second ion implantation mask individually by photolithography to form a third ion implantation mask, said first ion implantation mask having a mask region corresponding to the channel region and having a first opening corresponding to said source region, said second ion implantation mask being positioned in contact with an outer edge of said first ion implantation mask and configured to form a base region; (b) implanting impurities of the first conductivity type from said first opening with an ion beam using said third ion implantation mask to form said source region in the upper layer part of said silicon carbide drift layer; (c) removing said first ion implantation mask after the formation of said source region; and (d) implanting impurities of the second conductivity type with an ion beam from a second opening formed in said second ion implantation mask after the removal of said first ion implantation mask to form said base region deeper than said source region in the upper layer part of said silicon carbide drift layer.