Patent ID: 8283721

Claim:
A semiconductor device comprising: a semiconductor layer having a first face provided with a trench and a second face opposite to the first face; a gate electrode provided in the trench; and an insulating layer provided in the trench so as to insulate the semiconductor layer and the gate electrode from each other; wherein the semiconductor layer includes a first semiconductor layer of a first conductivity type, and a second semiconductor layer of a second conductivity type opposite to the first conductivity type, wherein the trench is formed so as to penetrate through the second semiconductor layer and to reach the first semiconductor layer, wherein the second semiconductor layer includes a close portion closer to the second face of the semiconductor layer than the trench is, wherein the semiconductor layer further includes a semiconductor region formed around the trench, wherein a recessed portion is provided at the first semiconductor layer, the second semiconductor layer, or the semiconductor region, and wherein the close portion and the recessed portion are disposed so as to overlap in a widthwise direction perpendicular to a depthwise direction of the trench.