Patent ID: 8564028

Claim:
A wide band gap semiconductor device comprising: a first conductivity type semiconductor substrate having a high impurity concentration; a first conductivity type drift layer having a lower impurity concentration than the semiconductor substrate and formed on one principal surface of the semiconductor substrate; a second conductivity type base layer having a higher impurity concentration than the drift layer and formed on the drift layer; and a first conductivity type source region selectively disposed on a principal surface of the base layer; a first trench having a depth extending from a principal surface of the source region to reach the drift layer; a control electrode which is filled through a gate insulating film in the first trench so as to be located in a position facing the source region, the base layer and the drift layer; a second trench provided near the first trench and having a depth extending from the principal surface of the base layer to reach the drift layer so as to be deeper than the first trench, wherein the second trench has a circular pattern so that a surface pattern of the first trench is surrounded by a surface of the second trench; a first main electrode which is disposed in the second trench to form a Schottky junction between the first main electrode and a surface of the drift layer located in the second trench so that the first main electrode covers both the principal surface of the source region and the principal surface of the base layer; and a second main electrode which is disposed on the other principal surface of the first conductivity type semiconductor substrate.