Patent ID: 7432579

Claim:
A semiconductor device comprising a MOS field-effect transistor and a Schottky barrier diode, the MOS field-effect transistor including: a semiconductor substrate of a first-conductivity type; a semiconductor layer of a second-conductivity type on the semiconductor substrate; a base region of the first-conductivity type provided in a surface portion of the semiconductor layer; a source region of the second-conductivity type provided in a surface portion of the base region; a drain region of the second-conductivity type provided in a surface portion of the semiconductor layer separately from the source region; a resurf layer of the second-conductivity type provided in a surface portion of the semiconductor layer between the source region and the drain region, the resurf layer having a lower impurity concentration than the drain region; a gate insulation film provided on the base region between the source region and the resurf layer; and a gate electrode provided on the gate insulation film, the Schottky barrier diode including: a Schottky electrode provided on the source region and the semiconductor layer, wherein the drain region is part of both the MOS field-effect transistor and the Schottky barrier diode, the Schottky electrode is in contact with the semiconductor layer, and the device further includes a second semiconductor region of the first-conductivity type provided near the base region under the Schottky electrode, the second semiconductor region extending to a deeper position than the base region.