Patent ID: 8637928

Claim:
A semiconductor device comprising: a base region of a second conductivity type including a source region of a first conductivity type; a drift region of the first conductivity type adjacent to the base region; an insulating layer provided from a surface to inside of the drift region; a drain region of the first conductivity type provided in the surface of the drift region and opposed to the source region across the base region and the insulating layer; a gate oxide film provided on a surface of the base region; and a gate electrode provided on the gate oxide film; as viewed in a direction perpendicular to the surface of the base region, the base region being surrounded by the drift region and the insulating layer, the source region and at least a part of the drain region extending generally parallel in a line shape, a length of a portion of the drift region sandwiched between the insulating layer and the base region being shorter in the generally parallel extending direction than in a direction generally perpendicular to the generally parallel extending direction.