Patent ID: 8169021

Claim:
A trench gate semiconductor device, comprising: a semiconductor layer of a first conductivity type; a diffusion region of a second conductivity type formed as a planar structure on the semiconductor layer of the first conductivity type; a diffusion region of the first conductivity type positioned selectively on an upper side of the diffusion region of the second conductivity type so as to be in contact with the diffusion region of the second conductivity type; a gate electrode provided in a first trench via a gate insulation film, the first trench being formed in plurality in substantially one direction and each being formed to face the diffusion region of the first conductivity type and to penetrate through the diffusion region of the second conductivity type to reach the semiconductor layer of the first conductivity type; and a first semiconductor region of the second conductivity type provided at a position, at a first depth internally in the semiconductor layer of the first conductivity type, apart in a lateral direction from the diffusion region of the second conductivity type; a second semiconductor region of the second conductivity type provided at a position, at a second depth internally in the diffusion region of the second conductivity type, between adjacent trenches among the first trenches, the second depth being close to a depth of a boundary of the diffusion region of the second conductivity type and the semiconductor layer of the first conductivity type, and the first depth being substantially same as the second depth; and a main electrode formed in contact with the semiconductor layer of the first conductivity type and the diffusion region of the first conductivity type.