Semiconductor device and circuit having the same

A semiconductor device with a wide gap semiconductor, comprising:

• a vertical MISFET including:
• a semiconductor substrate that includes
• a back surface layer having a first conductivity type, arranged on a back surface side, and made of the wide gap semiconductor with a high impurity concentration and
• a drift layer having the first conductivity type, arranged on a front surface side, and made of the wide gap semiconductor with a lower impurity concentration than that of the back surface layer;
• a body layer having a second conductivity type, arranged over the drift layer, and made of the wide gap semiconductor;
• a source region having the first conductivity type, arranged in an upper layer portion of the body layer, and made of the wide gap semiconductor having a higher impurity concentration than that of the drift layer;
• a trench gate structure that is arranged in a trench disposed from a surface of the source region to a depth deeper than the body layer, and includes a gate insulating film arranged on an inner wall surface of the trench and a gate electrode arranged on the gate insulating film;
• a source electrode that is electrically connected to the source region;
• a drain electrode that is electrically connected to the back surface layer of the semiconductor substrate on the back surface side;
• and
• an interlayer insulating film sandwiched between the source electrode and the gate electrode in a depth direction of the trench, the source region being formed between the interlayer insulating film and the body layer,
• wherein:
• the gate insulating film is made of a material having a barrier against a minority carrier in the body layer and having no barrier against a minority carrier in the drift layer, and
• the gate insulating film directly contacts the drift layer.