Silicon carbide substrate, silicon carbide epitaxial substrate, method for producing silicon carbide semiconductor device, and method for producing silicon carbide crystal

Abstract

This silicon carbide substrate has a first main surface and a second main surface that is on the reverse side of the first main surface. First voids are present in the first main surface. The surface density of the first voids is less than 0.04 voids per cm2. When viewed along a straight line perpendicular to the first main surface, the width of the first voids is 10-100 μm. When viewed along a straight line parallel to the first main surface, the width of the first voids increases from the first main surface toward the second main surface. When viewed along a straight line parallel to the first main surface, the depth of the first voids is smaller than the thickness of the silicon carbide substrate. The first main surface is a carbon surface or a surface that is inclined to the carbon surface at an off angle of 8° or less.