Patent ID: 7727831

Claim:
A semiconductor device having a field effect transistor, comprising: a semiconductor layer; a first trench formed in the semiconductor layer; a gate electrode provided within the first trench via a gate insulating film intervening therebetween; a second trench formed in the semiconductor layer; a first insulating film provided in an interior of the second trench; a protection element provided in the second trench via the first insulating film, the protection element having a first node and a second node; a second insulating film provided inside the second trench and covering the protection element, the second insulating film having a first via corresponding to the first node and a second via corresponding to the second node; a source region provided in the semiconductor layer; a source electrode connected to the source region; and a drain electrode provided on a back surface of the semiconductor layer, wherein a bottom surface of the second trench is positioned to be lower than a bottom surface of the first trench, and wherein the first node of the protection element is electrically connected to the gate electrode via the first via of the second insulating film and the second node of the protection element is connected to the source electrode via the second via of the second insulating film.