Patent ID: 7816741

Claim:
A semiconductor device including an insulated gate bipolar transistor, comprising: a first semiconductor layer of a first conductivity type impurity region; a second semiconductor layer of a second conductivity type impurity region formed on the first semiconductor layer; a plurality of trench formed regions formed through the second semiconductor layer from the main surface thereof; a gate insulating film and a gate electrode formed within the respective trench formed regions; a contact layer of the second conductivity type impurity region formed on the main surface of the second semiconductor layer; an emitter layer of the first conductivity type impurity region formed on the main surface of the second semiconductor layer; a plurality of third semiconductor layers of the second conductivity type impurity region which is formed spaced apart from the second semiconductor layer on the main surface of the first semiconductor layer; and a fourth semiconductor layer of the first conductivity type impurity region formed between the second semiconductor layer and the first semiconductor layer within an area contained in the second semiconductor layer in plane view, formed only inside an edge of the second semiconductor layer in plane view, and formed continuously across a plurality of the trench formed regions.