Silicon carbide epitaxial substrate and method of manufacturing silicon carbide epitaxial substrate

Abstract

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.

What is claimed is: 
     
         1 . A silicon carbide epitaxial substrate having a main surface, comprising:
 a base substrate; and   a silicon carbide epitaxial layer formed on said base substrate and including said main surface,   said main surface having a surface roughness of 0.6 nm or less,   a ratio of standard deviation of a nitrogen concentration in said silicon carbide epitaxial layer at a surface layer including said main surface within a plane of said silicon carbide epitaxial substrate to an average value of said nitrogen concentration in said silicon carbide epitaxial layer at said surface layer within the plane of said silicon carbide epitaxial substrate being 15% or less.   
     
     
         2 . The silicon carbide epitaxial substrate according to  claim 1 , wherein a background concentration of the nitrogen in said silicon carbide epitaxial layer is 1×10 15  cm −3  or less. 
     
     
         3 . The silicon carbide epitaxial substrate according to  claim 1 , wherein the nitrogen concentration in said silicon carbide epitaxial layer is 2×10 16  cm −3  or less. 
     
     
         4 . The silicon carbide epitaxial substrate according to  claim 1 , wherein the silicon carbide epitaxial substrate has an outer diameter of 100 mm or more.