Patent ID: 8421151

Claim:
A semiconductor device comprising a plurality of unit cells that are arranged either one-dimensionally or multi-dimensionally, each said unit cell comprising: a substrate, which is made of a wide-bandgap semiconductor of a first conductivity type; a drift layer, which is arranged on the substrate and which is made of the wide-bandgap semiconductor of the first conductivity type; a body region of a second conductivity type, which is defined in the drift layer; a first doped region of the first conductivity type, which is defined in the body region; a second doped region of the first conductivity type, which is arranged adjacent to the body region and defined in a surface region of the drift layer; a third doped region of the first conductivity type, which is arranged between the second doped region of the first conductivity type and an adjacent unit cell's second doped region of the first conductivity type and defined in the surface region of the drift layer so as to be in contact with the second doped region of the first conductivity type; a fourth doped region of the first conductivity type, which is defined in the drift layer adjacent to the third doped region of the first conductivity type and includes a vertex of the unit cell when viewed from over the surface of the drift layer; a gate insulating film, which is arranged so as to contact with the surface of the drift layer at least between the first and second doped regions of the first conductivity type; a gate electrode, which is arranged on the gate insulating film; a first ohmic electrode, which is electrically connected to the first doped region of the first conductivity type; and a second ohmic electrode, which is electrically connected to the other surface of the substrate that is opposite to its surface with the drift layer, wherein the dopant concentration of the third doped region of the first conductivity type is lower than that of the second doped region of the first conductivity type and equal to or higher than that of the drift layer, and wherein the dopant concentration of the fourth doped region of the first conductivity type is lower than that of the third doped region of the first conductivity type, and wherein the fourth doped region of the first conductivity type is not provided where two sides of two adjacent unit cells are in contact with each other.