Patent ID: 7573096

Claim:
A semiconductor device comprising: a first semiconductor layer, which has a first main surface and a second main surface which face each other, and is made of a semiconductor of a first conductive type; a second semiconductor layer, which is exposed onto the first main surface, is made of a semiconductor of the first conductive type, and has an impurity concentration lower than that of the first semiconductor layer; a plurality of trenches formed in a surface of the second semiconductor layer; a gate insulating film formed in each of the trenches; a gate electrode surrounded by the gate insulating film; a first area of a second conductive type, which is formed in the surface of the second semiconductor layer, between two of the trenches; second areas of the first conductive type, which are formed in a surface of the first area, and have an impurity concentration higher than that of the second semiconductor layer, wherein the second areas interpose an area of the second conductive type, which has an impurity concentration higher than that of the first area; a third area of the second conductive type, which is formed in the surface of the second semiconductor layer, between one of the trenches, which is adjacent to the first area, and another one of the trenches, in a manner such that said one of the trenches, which is adjacent to the first area, is interposed between the first area and the third area; a first electrode, which contacts surfaces of the second and third areas; a second electrode, which contacts the second main surface, wherein: the total amount of impurities, which function as impurities of the second conductive type in the first area, is larger than the total amount of impurities, which function as impurities of the second conductive type in the third area.