Power semiconductor device

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≧2×1012 cm−2.