Patent ID: 8222648
Filing Date: 2012-07-17
Classification: H01L

Abstract:
1. A silicon carbide semiconductor device, comprising: a silicon carbide substrate of a first conductivity type; a base area of a second conductivity type formed in a surface layer of the silicon carbide substrate; source areas of the first conductivity type formed in a surface layer of the base area; a base contact area of the second conductivity type formed in a surface layer of the base area, the base contact area being shallower than the base area and being sandwiched between the source areas; a source contact electrode configured to realize an ohmic contact simultaneously with the source areas and the base contact area; a drain electrode configured to realize an ohmic contact with the silicon carbide substrate; gate electrodes made of polycrystalline silicon, the gate electrodes being placed above the surface layer of the silicon carbide substrate at which at least the base area is exposed; and ONO insulating films sandwiched between the silicon carbide substrate and the gate electrode to thereby form gate structures, the ONO insulating films including the followings formed sequentially from the silicon carbide substrate, respectively: a first oxide silicon film (O) formed directly on the silicon carbide substrate, a SiN film (N) formed directly on the first oxide silicon film (O), a SiN sideface thermally-oxidized film being disposed on an edge sideface of the SiN film (N), and a SiN thermally-oxidized film (O) formed directly on the SiN film (N), wherein nitrogen is included in at least one of the following places: in the first oxide silicon film (O) and in a vicinity of the silicon carbide substrate, and in an interface between the silicon carbide substrate and the first oxide silicon film (O).