Reverse conducting semiconductor device and method for manufacturing reverse conducting semiconductor device

A reverse conducting semiconductor device having an insulated gate bipolar transistor region and a diode region, the reverse conducting semiconductor device comprising:

• a semiconductor substrate included in the insulated gate bipolar transistor region and the diode region, the semiconductor substrate having a first principal surface and a second principal surface opposite to the first principal surface, the semiconductor substrate including
• a drift layer extending over the insulated gate bipolar transistor region and the diode region and having a first conductivity type,
• a base layer arranged between the drift layer and the first principal surface in the insulated gate bipolar transistor region, the base layer having a second conductivity type different from the first conductivity type,
• an emitter layer arranged between the base layer and the first principal surface in the insulated gate bipolar transistor region, the emitter layer having the first conductivity type,
• a base contact layer arranged between the base layer and the first principal surface in the insulated gate bipolar transistor region, the base contact layer forming a part of the first principal surface, the base contact layer having the second conductivity type,
• a collector layer arranged between the drift layer and the second principal surface in the insulated gate bipolar transistor region, the collector layer having the second conductivity type,
• an anode layer arranged between the drift layer and the first principal surface in the diode region, the anode layer having the second conductivity type,
• an anode contact region arranged between the anode layer and the first principal surface in the diode region, the anode contact region forming a part of the first principal surface, the anode contact region having a second conductivity type impurity concentration peak value higher than that of the anode layer, the anode contact region having the second conductivity type, and
• a cathode layer arranged between the drift layer and the second principal surface in the diode region, the cathode layer having the first conductivity type;
• an insulated gate structure for forming, with the base layer, a channel for controlling an electrical path between the emitter layer and the drift layer;
• a collector electrode electrically connected to the collector layer and the cathode layer;
• and
• an emitter electrode in contact with the base contact layer and the anode contact region,
• wherein the anode contact region includes a first anode contact layer having a lower net concentration and a higher first conductivity type impurity concentration than the base contact layer.