Patent ID: 7768066

Claim:
A semiconductor device comprising: a first semiconductor layer of a first conductivity type; a second semiconductor layer formed on the first semiconductor layer, having a lower impurity concentration than that of the first semiconductor layer, and constituting a drift region of the first conductivity type; a third semiconductor layer of a second conductivity type opposite to the first conductivity type, the third semiconductor being formed on the second semiconductor layer, a junction being formed between the second semiconductor layer and the third semiconductor layer; a fourth semiconductor layer of the first conductivity type, the fourth semiconductor layer being formed on the third semiconductor layer; a trench at least extending through the third semiconductor layer and forming a recessed portion connected with the second semiconductor layer; an insulating layer formed on a side surface and a bottom surface of the trench; a semiconductor region of the second conductivity type, the semiconductor region being formed in the second semiconductor layer and located around and outside a bottom portion of the trench; a channel region of the first conductivity type, the channel region being formed on the side surface of the trench, extending from the fourth semiconductor layer to the semiconductor region provided in the second semiconductor layer, and having a higher impurity concentration than that of the second semiconductor layer constituting the drift region; and a gate electrode insulated by the insulating layer formed on the side surface and the bottom surface of the trench, at least a part of the gate electrode being formed in the trench.