Patent ID: 6972458

Claim:
A semiconductor device comprising: a source region of a first conductivity type; a base region of a second conductivity type formed in a surface layer portion on a principal surface in a semiconductor substrate of a first conductivity type, the source region being formed to be shallower than the base region in the surface layer portion on the principal surface in the base region; a drain region of the first conductivity type formed in a position apart from the base region in the surface layer portion on the principal surface; a well region of the first conductivity type disposed in the surface layer portion on the principal surface and formed to be deeper than the drain region and to have a higher concentration than the semiconductor substrate in a region including the drain region and in contact with the base region; a trench formed in the principal surface of the semiconductor substrate to penetrate the base region in a direction toward the drain region from the source region as a planar structure thereof; a gate electrode formed via a gate insulating film in the inside of the trench; a source electrode electrically connected to the source region; and a drain electrode electrically connected to the drain region.