Patent ID: 8421157

Claim:
A horizontal semiconductor device, comprising: a plurality of unit transistors, a first one of the plurality of unit transistors abutting and adjacent to a second one of the plurality of unit transistors, each of the plurality of unit transistors including a semiconductor substrate of a first conductivity type; a semiconductor region of a second conductivity type formed on said semiconductor substrate; a collector layer of the first conductivity type formed within said semiconductor region; an endless base layer of the first conductivity type formed within said semiconductor region such that said endless base layer is off said collector layer but surrounds said collector layer; an endless first emitter layer of the second conductivity type formed in said endless base layer; and an emitter electrode electrically connected with the endless first emitter layer, wherein a movement of carriers between said endless first emitter layer and said collector layer is controlled in a channel region formed in said endless base layer, an insulation film is disposed between said semiconductor substrate and said semiconductor region, and a region of the first conductivity type is disposed in said semiconductor region to contact with a surface of said endless base layer nearest said semiconductor substrate, the emitter electrode extending farther toward the collector layer than the region of the first conductivity type extends toward the collector layer.