Patent ID: 7622754

Claim:
A semiconductor device comprising: a first base layer of a first conductivity type having high resistivity; a collector layer of a second conductivity type formed on a reverse side of the first base layer; a second base layer of the second conductivity type formed on an obverse side of the first base layer; an emitter layer of the first conductivity type formed on a surface of the second base layer; a set of gate electrodes formed inside trenches extending in a first direction and intruding through the emitter layer and the second base layer into intermediate depths of the first base layer, with gate insulating films in between; a collector electrode connected to the collector layer; and an emitter electrode connected to the emitter layer and the second base layer, wherein the emitter layer comprises: a set of first emitter layers extending along the trenches in the first direction; and a set of second emitter layers extending in a second direction perpendicular to the first direction for a ladder form interconnection between first emitter layers, and the semiconductor device comprises a base contact layer having a higher impurity density than the second base layer of the second conductivity type, and configured to envelope second emitter layers.