Method of manufacturing semiconductor device

A method of manufacturing a semiconductor device which comprises:

• a semiconductor substrate body;
• a hetero semiconductor region which is in contact with a major surface of the semiconductor substrate body, and whose bandgap is different from that of the semiconductor substrate body;
• a gate electrode arranged in a junction part between the hetero semiconductor region and the semiconductor substrate body with the gate insulating film interposed between the gate electrode and the junction part;
• a source electrode connected to the hetero semiconductor region;
• and a drain electrode ohmically connected with the semiconductor substrate body,
• the method comprising:
• forming a hetero semiconductor layer on at least the major surface of the semiconductor substrate body of a first conductivity type;
• etching the hetero semiconductor layer selectively by use of a mask layer having openings in way that the hetero semiconductor layer remains to be not etched with a predetermined thickness;
• oxidizing an exposed parts of the hetero semiconductor layer;
• forming the hetero semiconductor region by etching a oxidized film formed in the oxidizing;
• and
• forming the gate insulating film in a way that the gate insulating film makes an intimate contact with the hetero semiconductor region and the semiconductor substrate body.