Patent ID: 8659065

Claim:
A semiconductor device comprising: a first conductivity-type drift layer; a second conductivity-type base layer on a front side of the drift layer; a plurality of trench gate structures, each trench gate structure including a trench reaching the drift layer by penetrating the base layer, a gate insulation layer on a wall surface of the trench, and a gate electrode on the gate insulation layer, the trench gate structure having a length direction parallel to a planar direction of the drift layer, a width direction parallel to the planar direction of the drift layer and perpendicular to the length direction, and a depth direction perpendicular to the planar direction of the drift layer; a first conductivity-type emitter layer located in a surface portion of the base layer and located adjacent to the trench gate structure; a second conductivity-type collector layer located across the drift layer from the emitter layer, and a second conductivity-type contact layer located in the surface portion of the base layer and located between adjacent trench gate structures across the emitter layer, wherein the trench gate structure has a bottom portion and an opening portion, the bottom portion defining a bottom of the trench gate structure, the opening portion located on an opposite side of the trench gate structure from the bottom portion in the depth direction, the bottom portion of the trench gate structure is located in the drift layer and expands in the width direction so that a distance between the bottom portions of adjacent trench gate structures is less than a distance between the opening portions of adjacent trench gate structures in the width direction, a thickness of the gate insulation layer on the wall surface of the trench of the bottom portion is greater than a thickness of the gate insulation layer on the wall surface of the trench of the opening portion, the contact layer is located facing the drift layer between the bottom portions of adjacent trench gate structures, a depth of the contact layer is greater than a depth of the emitter layer from a surface of the base layer in the depth direction, and a width of the contact layer is greater than the distance between the bottom portions of adjacent trench gate structures in the width direction.