Silicon carbide semiconductor device and method of manufacturing silicon carbide semiconductor device
A silicon nitride film having a thickness in a range from 1 [nm] to 3 [nm] is deposited on a front surface of a silicon carbide semiconductor base, by an ALD method. Next, on the silicon nitride film, for example, a silicon oxide film having a thickness in a range from 20 [nm] to 100 [nm] is deposited. After deposition of the silicon oxide film, for example, heat treatment is performed at a temperature in a range from 1100 degrees C. to 1350 degrees C., in a gas atmosphere that includes oxygen. By this heat treatment, nitrogen surface density of an interface of the silicon carbide semiconductor base and the silicon oxide film (gate insulating film) is increased, reducing interface state density of the interface of the silicon carbide semiconductor base and the silicon nitride film.
1. A silicon carbide semiconductor device, comprising:
a semiconductor base including silicon carbide; and
a gate insulating film provided on a surface of the semiconductor base, wherein
a nitrogen surface density at an interface of the semiconductor base and the gate insulating film is in a range of 6×10 14 /cm 2 to 1.2×10 15 /cm 2 , wherein
a half width of a peak of a nitrogen profile in a thickness direction in a region including the interface of the semiconductor base and the gate insulating film, is in a range of 2 nm to 4 nm.
2. The silicon carbide semiconductor device according to claim 1 , wherein
hydrogen volume densities in the gate insulating film and at the interface of the semiconductor base and the gate insulating film are 1×10 21 /cm 3 or less.
3. The silicon carbide semiconductor device according to claim 2 , wherein
the hydrogen volume densities in the gate insulating film and at the interface of the semiconductor base and the gate insulating film are 1×10 20 /cm 3 or less.
4. The silicon carbide semiconductor device according to claim 1 , wherein
the surface of the semiconductor base, forming the interface with the gate insulating film, is in a (0001) plane, a (000-1) plane, a (1-100) plane, or a (11-20) plane.
5. A method of manufacturing a silicon carbide semiconductor device, the method comprising:
forming on a front surface of a semiconductor base including silicon carbide, a silicon nitride film having a thickness in a range of lnm to 3 nm;
forming on the silicon nitride film, a gate insulating film; and
causing nitrogen atoms in the silicon nitride film to react with the semiconductor base by a heat treatment in an atmosphere that includes oxygen, after the forming of the gate insulating film.
6. The method according to claim 5 , wherein causing the nitrogen atoms to react with the semiconductor base includes performing the heat treatment at a temperature in a range of 1100 degrees C. to 1350 degrees C.
7. The method according to claim 5 , wherein the forming the silicon nitride film includes forming the silicon nitride film by a chemical vapor disposition method that includes an atomic layer deposition method.