Silicon carbide semiconductor device

A method for manufacturing a silicon carbide semiconductor device comprising the steps of:

• preparing a substrate made of silicon carbide having a hexagonal crystal structure and having a main surface;
• forming a silicon carbide layer of a first conductivity type on said main surface of said substrate;
• forming a body region of a second conductivity type having an impurity density of 5×1016 cm−3 or greater at said silicon carbide layer;
• forming a trench having a side wall inclined relative to said main surface to extend through said body region using a thermal etching;
• forming a gate insulating film on said side wall of said trench;
• and
• forming a gate electrode on said gate insulating film such that said gate electrode has a threshold voltage which allows a weak inversion layer to be formed in said body region, said threshold voltage being 2 V or greater in a temperature range of not less than a room temperature and not more than 100° C. and such that channel mobility of electrons is 30 cm2/Vs or greater at a room temperature.