Patent ID: 7692239

Claim:
A MIS-type semiconductor device comprising: a base region of a second conductivity; a source region of a first conductivity type in the surface of the base region; a drift region of the first conductivity type in the surface of the base region and laterally spaced from the source region; a gate insulation film on the surface of the base region between the source region and the drift region; and a gate electrode formed on the gate insulation film, wherein the base region in contact with the gate insulation film has an impurity concentration peak positioned more closely to the drift region than to the source region, and wherein the drift region comprises a first drift region and a second drift region, the first drift region being doped heavier than the second drift region, at least a part the surfaces of the first drift region and the gate electrode overlap each other, and an edge of the second drift region is positioned farther from the gate electrode than the first drift region so that the second drift region is not exposed to the surface of the base region beneath the gate electrode.