Patent ID: 7893467

Claim:
A silicon carbide semiconductor device comprising: a substrate made of silicon carbide, having a first conductivity type, and having a principal surface and a rear surface opposite to each other; a drift layer made of silicon carbide, having a first conductivity type, and disposed on the principal surface of the substrate, wherein an impurity concentration of the drift layer is lower than that of the substrate; an insulating layer disposed on the drift layer and including an opening, wherein a part of the substrate and a part of the drift layer define a cell, which is positioned between the opening of the insulating layer and the rear surface of the substrate; a Schottky electrode contacting the drift layer through the opening of the insulating layer to provide a Schottky contact; an ohmic electrode disposed on the rear surface of the substrate; a Schottky barrier diode provided by the ohmic electrode and the Schottky electrode; a resurf layer disposed in a surface portion of the drift layer, having a second conductivity type, and surrounding the cell, wherein the resurf layer provides a termination structure; a plurality of second conductivity type layers disposed in another surface portion of the drift layer, contacting the Schottky electrode, surrounded by the resurf layer, and separated from one another, wherein: the drift layer and the plurality of second conductivity type layers provide a plurality of PN diodes; each second conductivity type layer has a radial width with respect to a center of a contact region between the Schottky electrode and the drift layer; the radial width of one of the plurality of second conductivity type layers is smaller than that of another one of the plurality of second conductivity type layers, the another one being disposed closer to the center of the contact region than the one of the plurality of second conductivity type layers; the plurality of second conductivity type layers includes a center member, which is disposed at the center of the contact region between the Schottky electrode and the drift layer; the plurality of second conductivity type layers further includes a plurality of ring members, each of which surrounds the center member; one of the plurality ring members is defined as a innermost ring member, which is disposed adjacent to the center member; and a width of the innermost ring member is larger than that of the center member and that of the plurality of ring member except the innermost ring member.