Method for forming identification marks on silicon carbide single crystal substrate, and silicon carbide single crystal substrate

1. A method for forming an identification mark on a silicon carbide single crystal substrate, comprising:

(a) scanning a principal surface of a silicon carbide single crystal substrate with a laser beam at a first energy density such that a groove is formed in the principal surface of the silicon carbide single crystal substrate, thereby forming an identification mark which is constituted of one or more grooves in the principal surface of the silicon carbide single crystal substrate; and

(b) scanning an inside of the groove formed in the principal surface of the silicon carbide single crystal substrate with a laser beam at a second energy density that is lower than the first energy density.

2. The method of claim 1 , wherein a width of the groove is not less than 50 μm, and a depth of the groove is not less than 20 μm.

3. The method of claim 1 wherein, at least at a bottom surface of an internal surface of the groove, the surface roughness Ra is not more than 1 μm.

4. The method of claim 1 , further comprising

(c) after step (b), performing mechanical polishing on the principal surface of the silicon carbide single crystal substrate.

5. The method of claim 4 wherein, after step (c), gas phase etching is performed on the principal surface of the silicon carbide single crystal substrate.

6. The method of claim 1 , wherein the surface roughness Ra of the principal surface of the silicon carbide single crystal substrate is not less than 0.1 nm and not more than 2.0 nm.