Patent ID: 7319257

Claim:
A power semiconductor device comprising: a first base layer of a first conductivity type; a collector layer of a second conductivity type disposed on the first base layer; a trench disposed in the first base layer at a position remote from the collector layer; a second base layer of the second conductivity type disposed on the first base layer and in contact with the trench; an emitter layer of the first conductivity type disposed on the second base layer; a gate electrode disposed in the trench to face, through a gate insulating film, a portion of the second base layer sandwiched between the first base layer and the emitter layer; a collector electrode disposed on the collector layer; an emitter electrode disposed on the second base layer and the emitter layer; a barrier layer of the first conductivity type disposed between the first base layer and the second base layer, and having an impurity concentration higher than that of the first base layer, the barrier layer providing, in an on-state of the device, an increase in resistance against flow of carriers of the second conductivity type from the first base layer into the emitter electrode through the second base layer, thereby improving injection efficiency of carriers of the first conductivity type from the emitter layer into the first base layer; a diverter layer of the second conductivity type disposed on the first base layer, to exhaust carriers of the second conductivity type from the first base layer; and a rectifying element including a portion of the first conductivity type electrically connected to the emitter electrode, and a portion of the second conductivity type electrically connected to the diverter layer, the rectifying element becoming conductive by a change in potential of the diverter layer, thereby exhausting carriers of the second conductivity type from the diverter layer into the emitter electrode, in process of turn-off of the device.