Patent ID: 8912632

Claim:
A semiconductor device comprising: a first electrode; a first base layer provided on the first electrode and having a first conductivity type; a second base layer provided on the first conductivity type base layer and having a second conductivity type; a first semiconductor layer provided on the second conductivity type base layer and having the first conductivity type; a gate electrode having a first end at a first level that is closer to a first interface between the first semiconductor layer and the second base layer than to a second interface between the first base layer and the second base layer, and a second end at a second level that is closer to the second interface than to the first interface; a gate insulating film provided between the gate electrode and the second base layer; and a second electrode provided on the first semiconductor layer and electrically connected to the first semiconductor layer, wherein an impurity concentration in the first semiconductor layer is such that a concentration of minority carriers in the second base layer is not greater than an impurity concentration in the second base layer when a forward bias is applied across a pn junction between the second base layer and the first semiconductor layer.