Patent ID: 8772788

Claim:
A semiconductor device comprising: a semiconductor substrate having a principal surface and a reverse surface; a first silicon carbide semiconductor layer located on the principal surface of the semiconductor substrate, the first silicon carbide semiconductor layer including a drift region of a first conductivity type, a body region of a second conductivity type located on the drift region, and an impurity region of the first conductivity type located on the body region; a trench provided in the first silicon carbide semiconductor layer, running through the body region so as to reach inside of the drift region; a second silicon carbide semiconductor layer of the first conductivity type located at least on a side surface of the trench so as to be in contact with at least a portion of the drift region and at least a portion of the impurity region; a gate insulating film located on the second silicon carbide semiconductor layer; a gate electrode located on the gate insulating film; a first ohmic electrode in contact with the impurity region; and a second ohmic electrode located on the reverse surface of the semiconductor substrate; the body region includes a first body region which is in contact with the impurity region and in contact with the second silicon carbide semiconductor layer on the side surface of the trench, and a second body region which is in contact with the drift region and in contact with the second silicon carbide semiconductor layer on the side surface of the trench and has a smaller average impurity concentration than the first body region; potentials to be applied to the second ohmic electrode and the gate electrode with respect to the first ohmic electrode are Vds and Vgs, respectively, and a gate threshold voltage is Vth; where Vgs≧Vth, a current flows from the second ohmic electrode to the first ohmic electrode through the second silicon carbide semiconductor layer; and where 0 volt≦Vgs<Vth, a current flows from the first ohmic electrode to the second ohmic electrode through the second silicon carbide semiconductor layer before a current starts to flow from the body region to the drift region, as Vds becomes less than 0 volt.