Silicon carbide epitaxial substrate and method of manufacturing silicon carbide epitaxial substrate
A silicon carbide epitaxial substrate having a main surface (second main surface) includes: a base substrate; and a silicon carbide epitaxial layer formed on the base substrate and including the main surface (second main surface), the second main surface having a surface roughness of 0.6 nm or less, a ratio of standard deviation of a nitrogen concentration in the silicon carbide epitaxial layer at a surface layer including the main surface (second main surface) within a plane of the silicon carbide epitaxial substrate to an average value of the nitrogen concentration in the silicon carbide epitaxial layer at the surface layer within the plane of the silicon carbide epitaxial substrate being 15% or less.
1. A method of manufacturing a silicon carbide epitaxial substrate, comprising the steps of:
preparing a base substrate;
placing said base substrate in a silicon carbide growth device; and
forming a silicon carbide epitaxial layer on said base substrate by supplying said base substrate with a source material gas used to form said silicon carbide epitaxial layer and heating said base substrate to an epitaxial growth temperature,
said silicon carbide growth device including a member having a coating that is exposed to said source material gas and that is heated to said epitaxial growth temperature,
wherein the member includes a substrate holder supporting the base substrate, a heat generator positioned around the substrate holder, and the coating on the substrate holder and the heat generator,
wherein a nitrogen concentration of the substrate holder, the heat generator, and the coating is 10 ppm or less.
2. The method of manufacturing the silicon carbide epitaxial substrate according to claim 1 , wherein in the step of forming said silicon carbide epitaxial layer, said source material gas includes ammonia gas as a dopant gas.
3. The method of manufacturing the silicon carbide epitaxial substrate according to claim 1 , wherein said base substrate prepared in the step of preparing said base substrate has an outer diameter of 100 mm or more.
4. The method of manufacturing the silicon carbide epitaxial substrate according to claim 1 , wherein the coating encompasses the substrate holder.
5. The method of manufacturing the silicon carbide epitaxial substrate according to claim 1 , wherein the coating covers the surface of the heat generator that is exposed to said source material gas.
6. The method of manufacturing the silicon carbide epitaxial substrate according to claim 1 , wherein the coating covers the surface of the member that is exposed to said source material gas.