Silicon carbide semiconductor device and process for its preparation

The silicon carbide semiconductor device comprising: a semiconductor substrate (1), which is made of single-crystal silicon carbide and a main surface (1a) and one of the main surface (1a) opposite the back surface (1b); a drift layer (2), which is made of silicon carbide of a first conductivity type on the principal surface (1a) of the semiconductor substrate (1) and having a doping concentration which is lower than a doping concentration of the semiconductor substrate (1); a base region (3a, 3b) having a second conductivity type, on a predetermined region of the drift layer (2) is arranged and has a predetermined thickness; a source region (4a, 4b) having the first conductivity type, on a predetermined surface portion of the base region (3a, 3b) and shallower than the depth of the base region (3a, 3b); a surface channel layer (5), which is made of silicon carbide of the first conductivity type on the surface portions of both the drift layer (2) and the base region (3a, 3b) and having a predetermined concentration and a predetermined thickness (for a connection between the source region 4a , 4b) and the drift layer (2); a gate insulating film (7) which is arranged on a surface of the surface channel layer (5), wherein the gate insulating film comprises a film (7a) having a high dielectric constant; a gate electrode (8) which is arranged on the gate insulating film (7); (4a, 4b) is arranged a source electrode (10) formed on the source region; and a back electrode (11) formed on the back surface (1b) of the semiconductor substrate (1) is arranged, wherein the major surface (1a) includes at least two surfaces, one of which is inclined from a (0001) Si surface by an angle in a range between 10 degrees and 20 degrees and the other is the (0001) Si surface.