Abstract: A semiconductor device comprises a field effect transistor and a schottky-barrier diode mounted in the same semiconductor substrate, the semiconductor device having buried doped layers buried at a predetermined interval in a drift layer of a first conductivity type in a schottky-barrier diode region so as to have a predetermined depth, the buried doped layers having a second conductivity type.

Abstract: A semiconductor device comprises a first semiconductor layer of a first conductivity type provided on a semiconductor substrate of the first conductivity type, a base layer of a second conductivity type provided in the first semiconductor layer, for defining a vertical MISFET including source regions and a gate electrode on a gate insulation film, a Schottky barrier diode (SBD)-forming region provided in the first semiconductor layer around the base layer, a guard ring region of the second conductivity type provided around SBD-forming region, a first main electrode disposed above the first semiconductor layer and provided in common as both a source electrode of the MISFET and an anode of the SBD, a surface gate electrode disposed above the first semiconductor layer, and a second main electrode provided in common as a drain electrode of the MISFET and a cathode of the SBD.