Patent ID: RE40705

Claim:
A high-breakdown-voltage semiconductor apparatus comprising: a first-conductivity-type base layer; a second-conductivity-type base layer formed on a surface of the first-conductivity-type base layer; a first-conductivity-type source layer formed on a surface of the second-conductivity-type base layer; a gate electrode provided over that portion of the second-conductivity-type base layer, which is interposed between the first-conductivity-type source layer and the first-conductivity-type base layer, with a gate insulation film interposed between the gate electrode and the interposed portion of the second-conductivity-type base layer; a second-conductivity-type drain layer formed on a surface of the first-conductivity-type base layer, which is opposed to the surface thereof on which the second-conductivity-type base layer; a drain electrode put in contact with the second-conductivity-type drain layer; and a source electrode put in contact with the first-conductivity-type source layer and the second-conductivity-type base layer, wherein when a gate capacitance of that portion of the gate electrode, under which a channel is formed, is Cg [F], a resistance in a channel length direction of that portion of the gate electrode, under which the channel is formed, is Rg [Ω], a threshold voltage, which is to be applied to the gate electrode and application of which permits flow of a drain current, is Vth [V], a voltage to be applied to the gate electrode to cut off the drain current is Voff [V], and a ratio of increase in the drain voltage per unit time at the time of cutting off the drain current is dV/dt [V/s], the following condition is satisfied: |Vth−Voff|≧0.5·Cg·Rg·(dV/dt)