Patent ID: 8299548

Claim:
A method for manufacturing a semiconductor device, comprising: simultaneously forming a first field insulating film and at least one second field insulating film on a front face side of a semiconductor layer, the at least one second field insulating film being separated from the first field insulating film and thinner than the first field insulating film; forming a drift region of a first conductivity type in a region of the semiconductor layer including the first field insulating film and the second field insulating film; forming a gate insulating film on a front face of the semiconductor layer; forming a gate electrode on the gate insulating film; forming a drain region of the first conductivity type in the front face of the semiconductor layer on a side of the first field insulating film, the drain region having a first conductivity type impurity concentration higher than a first conductivity type impurity concentration of the drift region; and forming a source region of the first conductivity type in the front face of the semiconductor layer on a side of the second field insulating film.