Patent ID: 8378413

Claim:
A semiconductor device including a semiconductor substrate, a MISFET formed within a MISFET forming region of the semiconductor substrate, a first insulating film formed in the semiconductor substrate so as to surround the MISFET forming region, a well region a first conductivity type formed in the semiconductor substrate and arranged below the first insulating film so as to surround the MISFET forming region, the MISFET comprising: a semiconductor layer of a second conductivity type opposed to the first conductivity type formed in the semiconductor substrate, which serves as a drain region; a base region of the first conductivity type formed in the semiconductor substrate such that the base region is formed over the semiconductor layer, in which a channel is to be formed; a source region of the second conductivity type formed in the semiconductor substrate such that the source region is formed over the base region, which a side surface and an upper surface; a trench formed in the semiconductor substrate, which has contacts with the semiconductor layer, the base region and the source region; a gate insulating film formed inside the trench; a gate electrode formed over the gate insulating film and inside the trench; a second insulating film formed over the gate electrode and the upper surface of the source region; a contact hole formed in the second insulating film and the semiconductor substrate, whose bottom is located lower than the upper surface of the source region, the contact hole having contacts with the source region and the base region; and a source wiring formed in the contact hole electrically connected with the source region and the base region, wherein the source wiring has contacts with the upper surface of the source region and the side surface of the source region, and wherein the trench and the gate electrode extend in the well region such that a termination portion of the gate electrode extends over the first insulating film so as to extend a depletion layer gently below the first insulating film.