Patent ID: 7829946

Claim:
A semiconductor device including a MOSFET, comprising: a semiconductor substrate of an n-type, the semiconductor substrate having a main surface and a back surface opposite to the main surface; a plurality of transistor cell regions disposed on the semiconductor substrate, each of the plurality of transistor cell regions including: a plurality of first trenches disposed in the main surface of the semiconductor substrate, a well region of a p-type, in which a channel of the MOSFET is formed, disposed between the plurality of first trenches, a first gate insulating film of the MOSFET disposed in each of the plurality of first trenches, a first gate electrode of the MOSFET disposed on the first gate insulating film in each of the plurality of first trenches, and a source region of the MOSFET disposed in each well region, the source region being an n-type; a Schottky cell region disposed between the plurality of transistor cell regions in the semiconductor substrate, the Schottky cell region including: a plurality of second trenches disposed in the main surface of the semiconductor substrate, a second gate insulating film of the MOSFET disposed in each of the plurality of second trenches, a second gate electrode of the MOSFET disposed in each of the plurality of second trenches, gate lead-out wiring disposed over the main surface of the semiconductor substrate and connected to each second gate electrode, and a plurality of guard ring regions, which are p-type semiconductor regions, disposed in the main surface of the semiconductor substrate so as to enclose the respective second trenches; a source electrode of the MOSFET disposed over the main surface of the semiconductor substrate, the source electrode being electrically connected to the source region in each of the plurality of transistor cell regions, the source electrode being in contact with the main surface of the semiconductor substrate so as to form a Schottky junction in the Schottky cell region; and a drain electrode of the MOSFET disposed over the back surface of the semiconductor substrate and electrically connected to the semiconductor substrate.