Patent ID: 8754422

Claim:
A semiconductor device comprising: a semiconductor substrate having a principal surface and a reverse surface; a first silicon carbide layer arranged on the principal surface of the semiconductor substrate; a first impurity region of a first conductivity type arranged in the first silicon carbide layer; a body region of a second conductivity type arranged adjacent to the first impurity region in the first silicon carbide layer; a contact region of the second conductivity type which is arranged at a position deeper than the first impurity region in the body region and which contains an impurity of the second conductivity type at a higher concentration than the body region; a drift region of the first conductivity type arranged in a region of the first silicon carbide layer other than the body region and the first impurity region; and a first ohmic electrode in ohmic contact with the first impurity region and the contact region, wherein: a contact trench, which penetrates through the first impurity region, is provided in the first silicon carbide layer, the contact trench having a bottom surface and a side wall, and the side wall of the contact trench including a side wall lower portion present at a position deeper than a bottom surface of the first impurity region and a side wall upper portion present at a position at the same level or shallower than the bottom surface of the first impurity region; the first ohmic electrode is arranged in the contact trench and in contact with the contact region on at least a portion of the side wall lower portion and the bottom surface of the contact trench; and the side wall lower portion of the contact trench extends from a plane parallel to an upper surface of the first silicon carbide layer toward the upper surface of the first silicon carbide layer at an inclination angle α of less than 90 degrees with respect to the plane parallel to the upper surface of the first silicon carbide layer, and the side wall upper portion of the contact trench extends from another plane parallel to the upper surface of the first silicon carbide layer toward the upper surface of the first silicon carbide layer at an inclination angle β of less than 90 degrees with respect to the another plane parallel to the upper surface of the first silicon carbide layer and the inclination angle β is greater than the inclination angle α.