Semiconductor device with MOS transistors each containing trenches and schottky junctions

A semiconductor device that includes a semiconductor layer having a first main surface and a second main surface opposite to the first main surface, a source electrode provided on a side of the first main surface, and a drain electrode provided on a side of the second main surface, and gate electrodes that control a current flowing between the source electrode and the drain electrode by a voltage applied to the gate electrodes, the semiconductor device comprising:

• a sense source electrode provided separately from the source electrode and provided on the side of the first main surface of the semiconductor layer;
• a drift layer of a first conductivity type forming a main portion of the semiconductor layer;
• sense well regions of a second conductivity type selectively provided in a surface layer of the drift layer and electrically connected to the sense source electrode;
• sense source regions of the first conductivity type each selectively provided in a surface layer of each of the sense well regions and electrically connected to the sense source electrode;
• dummy sense well regions of the second conductivity type selectively provided in the surface layer of the drift layer separately from the sense well regions and electrically connected to the sense source electrode, and having no channel formed therein;
• gate insulating films provided between the dummy sense well regions and the gate electrodes;
• and
• diodes provided between the sense source electrode and the drift layer, each having a turn-on voltage lower than an operating voltage of a p-n diode formed of each of the sense well regions and the drift layer or of each of the dummy sense well regions and the drift layer, and allowing a current to flow from the sense source electrode toward the drain electrode, wherein
• the diodes are provided in such a way that they are mixed with facing areas in a dummy sense region in which the dummy sense well regions and the diodes are disposed, the facing areas each being an area in which one of the dummy sense well regions faces one of the gate electrodes via one of the gate insulating films.