Patent ID: 8598652

Claim:
A semiconductor device comprising: a first conductive type drift region; a second conductive type body region disposed on a front surface side of the drift region; a plurality of gate trenches disposed in a predetermined direction with an interval between one another, each of the plurality of gate trenches penetrating the body region and extending to the drift region; a gate electrode disposed within each of the plurality of gate trenches and opposing the body region; an insulator disposed within each of the plurality of gate trenches, each insulator being disposed between the gate electrode and a wall surface of the gate trench; and a second conductive type diffusion region provided at a bottom portion of each of the plurality of gate trenches to surround the bottom portion, each diffusion region being surrounded by the drift region, wherein an impurity concentration of each diffusion region is higher than that of the body region, and wherein in the drift region, an impurity concentration of a part near a side wall surface of the gate trench in the predetermined direction is lower than that of a central part between adjacent diffusion regions.