Patent ID: 8058686

Claim:
A semiconductor device comprising: a plurality of field effect transistors each including a semiconductor substrate of a first conductivity type, a semiconductor layer of the first conductivity type formed over a major surface of the semiconductor substrate and higher in resistance than the semiconductor substrate, a base region of a second conductivity type formed in a predetermined region of a surface layer portion of the semiconductor layer, a source region of the first conductivity type formed in a predetermined region of a surface layer portion of the base region, a source electrode formed so as to contact the base region and the source region, a gate electrode formed over the semiconductor layer and the base region through a gate insulating film interposed therebetween, and a drain electrode formed over a back surface of the semiconductor substrate, said field effect transistors being provided side by side with one another; a columnar intermediate region of the second conductivity type formed in a predetermined region of the surface layer portion of the semiconductor layer placed below each gate electrode, the columnar intermediate region being disposed to not contact the base regions; and connection regions of the second conductivity type respectively formed in predetermined regions of the surface layer portion of the semiconductor layer so as to contact the intermediate region and the base regions.