Semiconductor device and manufacturing method for the same

A semiconductor device comprising:

• an SiC substrate having first and second planes;
• a first conductive type SiC layer formed on the first plane side of the SiC substrate;
• a second conductive type first SiC region provided at a surface of the SiC layer;
• a first conductive type second SiC region provided at a surface of the first SiC region;
• a gate insulating film provided continuously on the surfaces of the SiC layer and the first SiC region, the gate insulating film including an oxide film or an oxynitride film in contact with the surface of the first SiC region, the oxide film or the oxynitride film containing at least one element selected from B (boron), Al (aluminum), Ga (gallium), In (indium), Sc (scandium), Y (yttrium), La (lantern), Mg (magnesium), Ca (calcium), Sr (strontium), and Ba (barium), a concentration peak of the element in the gate insulating film being on the first SiC region side of the gate insulating film, the concentration peak of the element being in the oxide film or the oxynitride film, the gate insulating film having a region with a concentration of the element of not higher than 1×1016 cm−3 on the opposite side to the SiC layer with the concentration peak of the element;
• a gate electrode formed on the gate insulating film;
• a first electrode formed on the second SiC region;
• and
• a second electrode formed on the SiC substrate.

A semiconductor device manufacturing method, comprising:

• forming, on an SiC layer, a first insulating film made of an oxide film or an oxynitride film that contains at least one element selected from B (boron), Al (aluminum), Ga (gallium), In (indium), Sc (scandium), Y (yttrium), La (lantern), Mg (magnesium), Ca (calcium), Sr (strontium), and Ba (barium);
• forming, on the first insulating film, a second insulating film with a concentration of the element being lower than that of the first insulating film;
• and
• forming a gate electrode on the second insulating film.