Semiconductor device, and method for manufacturing the same

A SiC semiconductor device comprising:

• a layer of semiconductor made of silicon carbide having a first face provided with at least one trench and a second face opposite to the first face;
• a gate electrode provided in the trench;
• and
• an insulating layer provided in the trench so as to insulate the layer of semiconductor and the gate electrode from each other,
• wherein the layer of semiconductor includes an n-type SiC semiconductor substrate with a high-concentration impurity, an n-type SiC semiconductor layer with a low-concentration impurity provided on the n-type SiC semiconductor substrate, a p-type SiC semiconductor layer provided on the n-type SiC semiconductor layer,
• wherein the trench is formed so as to penetrate through the p-type SiC semiconductor layer and to reach the n-type SiC semiconductor layer,
• wherein the p-type SiC semiconductor layer includes a close portion closer to the second face of the semiconductor layer than the trench is,
• the p-type SiC semiconductor layer includes a channel region that is formed along the trench and held in contact with the n-type SiC semiconductor layer,
• impurity concentration of the channel region is lower than impurity concentration of the close portion, and
• the n-type SiC semiconductor layer and the close portion of the p-type SiC semiconductor layer define a bottom boundary at a lower level than the trench, with a field concentration taking place at the bottom boundary when a reverse bias is applied, thereby causing a breakdown of the insulating layer to be avoided.