Patent ID: 8169034

Claim:
A semiconductor device comprising: a drift layer of a first conductivity type; a base layer of a second conductivity type provided on the drift layer; an emitter layer of the first conductivity type provided in part of an upper portion of the base layer; a buffer layer of the first conductivity type provided below the drift layer and having a higher effective impurity concentration than the drift layer; a high-resistance layer of the first conductivity type provided below the buffer layer and having a higher resistivity than the buffer layer; a collector layer of the second conductivity type provided in a partial region on a lower surface of the high-resistance layer; a contact layer of the first conductivity type provided in another partial region on the lower surface of the high-resistance layer; an emitter electrode connected to the base layer and the emitter layer; a trench gate electrode extending through the emitter layer and the base layer into the drift layer; a gate insulating film provided between the emitter layer, the base layer, and the drift layer on one hand and the trench gate electrode on the other; and a collector electrode connected to the collector layer and the contact layer.