Silicon carbide semiconductor device and method of manufacturing the same

A silicon carbide semiconductor device comprising:

• a drift layer of a first conductivity-type provided on a top surface side of a silicon carbide substrate of the first conductivity-type;
• a base region of a second conductivity-type provided on a top surface side of the drift layer;
• a main region of the first conductivity-type provided on the top surface side of the drift layer so as to be in contact with the base region;
• an insulated gate electrode structure provided to be in contact with the main region and the base region;
• a lifetime killer region provided to cover a bottom surface of the drift layer and including a recombination center having a point defect;
• and
• a buffer layer of the first conductivity-type provided between the silicon carbide substrate and the drift layer and having a higher impurity concentration than the drift layer,
• wherein a peak position of a concentration of the point defect in a depth direction is located inside the buffer layer.

A method of manufacturing a silicon carbide semiconductor device, comprising:

• epitaxially growing a drift layer of a first conductivity-type on a top surface side of a silicon carbide substrate of the first conductivity-type;
• forming a base region of a second conductivity-type on a top surface side of the drift layer;
• forming a main region of the first conductivity-type on the top surface side of the drift layer so as to be in contact with the base region;
• forming a gate insulating film so as to be in contact with the base region and the main region;
• forming a gate electrode so as to be in contact with the base region and the main region with the gate insulating film interposed:
• and
• forming a lifetime killer region at a depth covering a bottom surface of the drift layer by irradiating the top surface side of the drift layer with a lifetime killer after the epitaxially growing the drift layer and before the forming the gate insulating film.