Patent ID: 7800168

Claim:
A semiconductor device comprising: a base layer of a first conductivity type; a barrier layer of the first conductivity type formed above the base layer; a well layer of a second conductivity type formed above said barrier layer; a first trench formed within the barrier layer so as to extend from the top surface of the well layer toward the base layer; a second trench formed within the barrier layer adjacent to the first trench; a gate electrode formed in the trenches via a gate insulating film; a source layer of the first conductivity type selectively formed in a surface portion of the well layer so as to contact a side wall of the gate insulating film in the trenches; and a first main electrode electrically connected to the well layer and the source layer, wherein the distance between the first trench and the second trench is 2 μm or less and an impurity density of said barrier layer is higher than an impurity density of the base layer, the barrier layer extends to a region deeper than a bottom surface of the trenches, an emitter layer of the second conductivity type formed under the surface of the base layer on a side opposite to a side on which the first main electrode is formed, a second main electrode formed on the emitter layer and electrically connected to the emitter layer, and a total sum Qn of impurity densities in the region between the first trench and the second trench follows a relationship Qn≧ 2×10 12 cm −2 .