Patent ID: 7825449

Claim:
A silicon carbide semiconductor device, which is an inversion-type trench gate structure MOSFET, comprising: a first or second electrically conductive type substrate made of 4H silicon carbide and having a surface on one of a (000-1) c-plane and a (0001) Si-plane; a drift layer formed on the substrate with the first electrically conductive type silicon carbide having a lower impurity concentration than that of the substrate; a trench formed with a surface of the drift layer and having sidewalls formed with surfaces extending in one of a [11-20] direction and a [1-100] direction; base regions, formed in the drift layer in areas on both sides of the trench such that the trench is sandwiched and held in contact with the sidewalls of the trench, the base regions being made of the second electrically conductive type silicon carbide; source regions, formed on upper layer portions of the base regions in contact with the sidewalls of the trench such that the trench is sandwiched, which are made of the first electrically conductive type silicon carbide having a higher concentration than that of the drift layer; a gate oxide film, formed on an upper area of a bottom wall of the trench upon thermally oxidizing a surface of the trench, which has a thickness greater than that of each sidewall of the trench; a gate electrode formed in the trench in an area above the gate oxide film; a first electrode electrically connected to the source regions, respectively; a second electrode formed on the substrate at a rear surface thereof; second electrically conductive type deep layers formed on the drift layer in areas spaced from the trench with the base regions being intervened each in a depth equal to or greater than a depth of the trench and having a concentration equal to or greater than that of the base regions; and channel regions formed on surface areas of the base regions to allow an electric current to flow between the first and second electrodes via the source regions and the drift layer and upon controlling a voltage applied to the gate electrode.