Silicon carbide semiconductor device and method of manufacturing silicon carbide semiconductor device

A method of manufacturing a silicon carbide semiconductor device having, in a plan view thereof, an active region and a termination region surrounding a periphery of the active region, the method comprising:

• providing a semiconductor substrate containing silicon carbide, the semiconductor substrate having a first main surface and a second main surface;
• forming a first-conductivity-type region in the semiconductor substrate, a surface of the first-conductivity-type region forming the first main surface of the semiconductor substrate;
• selectively forming a plurality of first second-conductivity-type regions in the active region, the plurality of first second-conductivity-type regions being formed in the semiconductor substrate at the first main surface thereof, and being in contact with the first-conductivity-type region;
• forming a second second-conductivity-type region in the termination region, surrounding the active region;
• forming an oxide film on the first main surface of the semiconductor substrate, covering the first-conductivity-type region and the first second-conductivity-type regions;
• forming a plurality of openings in the oxide film, to thereby expose the first second-conductivity-type regions, by selectively removing the oxide film;
• forming a metal material film in the openings of the oxide film and in contact with first main surface of the semiconductor substrate, by sequentially stacking a first nickel film, an aluminum film, and a metal film having a melting point higher than that of aluminum;
• generating a compound layer on the first main surface of the semiconductor substrate through a first heat treatment that causes the metal material film and the semiconductor substrate to react, to thereby form the compound layer by self-alignment in the openings of the oxide film using the oxide film as a mask;
• removing an excess part of the metal material film excluding the compound layer;
• generating a nickel silicide in the compound layer to form a silicide film in ohmic contact with the semiconductor substrate, by a second heat treatment at a temperature higher than that of the first heat treatment;
• forming a contact hole connecting the openings by removing the oxide film in the active region after forming the silicide film;
• forming a first electrode on the first main surface of the semiconductor substrate in the contact hole, by sequentially stacking a titanium film and a metal electrode film containing aluminum, the first electrode being in contact with the first-conductivity-type region to form a plurality of Schottky regions, in contact with the silicide film to form a plurality of ohmic regions, and in contact with the first second-conductivity-type regions to form a plurality of non-operating regions;
• and
• forming a second electrode on the second main surface of the semiconductor substrate, wherein
• each of the openings is formed to have a width that is smaller than a width of each of the first second-conductivity-type regions, and
• the ohmic regions, the non-operating regions, and the Schottky regions are in the active region and are formed in a striped pattern, and
• the second second-conductivity-type region is connected to ohmic regions and the non-operating regions in the termination region.