Silicon carbide semiconductor device

A silicon carbide semiconductor device that includes an element region provided with a semiconductor element and a non-element region other than the element region, and in which a main current flows in a thickness direction of a silicon carbide substrate in the element region, the silicon carbide semiconductor device comprising:

• a semiconductor layer of a first conductivity type, the semiconductor layer being provided on a first main surface of the silicon carbide substrate;
• a first well region of a second conductivity type, the first well region being provided as an upper layer portion of the semiconductor layer in the element region;
• a first impurity region of the first conductivity type, the first impurity region being provided as an upper layer portion of the first well region;
• a first well contact region of the second conductivity type, the first well contact region being provided as the upper layer portion of the first well region and having a side surface bonded to the first impurity region;
• a gate insulating film provided on an end portion of the first impurity region, and on the first well region and the semiconductor layer;
• a gate electrode provided on the gate insulating film;
• a first contact brought into ohmic contact with the first impurity region and the first well contact region, and electrically connected to a first main electrode provided above the semiconductor layer;
• a second well region of the second conductivity type, the second well region being provided as an upper layer portion of the semiconductor layer of the non-element region;
• a second impurity region of the first conductivity type, the second impurity region being provided as an upper layer portion of the second well region;
• a second well contact region of the second conductivity type, the second well contact region being provided as the upper layer portion of the second well region and having a side surface bonded to the second impurity region;
• a field insulating film provided on the second well region, and
• at least one second contact passed through the field insulating film to form an ohmic contact with the second impurity region and the second well contact region, and electrically connected to the first main electrode;
• a boundary gate insulating film provided across a range between an end portion of the second impurity region and the end portion of the first impurity region, the end portion of the second impurity region being an end portion on a side nearer to a boundary between the element region and the non-element region, and the end portion of the first impurity region being an end portion of the first well region that is adjacent to the boundary;
• a boundary gate electrode provided on the boundary gate insulating film;
• and
• a second main electrode provided on a second main surface of the silicon carbide substrate, the second main surface being on an opposite side of the first main surface, wherein
• the second well contact region extends from below the at least one second contact toward the element region side, and
• the second impurity region extends from below the at least one second contact toward the non-element region side.