Patent ID: 8487343

Claim:
A semiconductor device, comprising: a semiconductor substrate of a first conductivity-type having a main surface on one side of said semiconductor substrate; an oxide film, which is provided in a part of said main surface of the semiconductor substrate; a separated region, being provided in said main surface of said semiconductor substrate and separated with insulation from other regions in said main surface of said semiconductor substrate, is surrounded by an oxide film groove provided in the semiconductor substrate of the first conductivity-type; two or more base regions of a second conductivity-type including an emitter region of the first conductivity-type, which are selectively formed in a surface region of said main surface within said separated region; a gate electrode, which is formed on the base regions between said semiconductor substrate of the first conductivity-type and the emitter region of the first conductivity-type; and a collector region of the second conductivity-type, wherein said two or more base regions of the second conductivity-type put said collector region of the second conductivity-type therebetween, said collector region of the second conductivity-type is disposed at a central portion of the separated region surrounded by the oxide film groove, and said emitter region of the first conductivity-type is disposed on a side of said oxide film groove, the gate electrode on a side of said oxide film groove is shorter than the gate electrode on said collector side, and wherein a high-density region of the first conductivity-type which is higher in density than said semiconductor substrate of the first conductivity-type is provided between said base regions of the second conductivity-type and below said base regions of the second conductivity-type, and does not exist below said gate electrode on the side of said oxide film groove.