Method of manufacturing semiconductor device

A method of manufacturing a semiconductor device, comprising:

• providing a device intermediate comprising a semiconductor substrate of a first general conductivity type, a semiconductor layer of the first general conductivity type disposed on a surface of the semiconductor substrate and a first insulating film disposed on the semiconductor layer;
• forming on the first insulating film a gate electrode having an opening therein;
• implanting a first impurity for the first general conductivity type into part of the semiconductor layer through the opening of the gate electrode;
• implanting a second impurity for a second general conductivity type into part of the semiconductor layer that is outside the gate electrode using the gate electrode as a mask;
• heating the device intermediate so that the first and second impurities are diffused so as to form an impurity region and a channel region that have an junction interface perpendicular to the surface of the semiconductor substrate;
• wherein during the heating of the device intermediate the impurity region of the first impurity and the channel region of the second impurity are formed simultaneously;
• forming a source region of the first general conductivity type in the channel region;
• and
• forming a second insulating film covering the gate electrode.