Abstract: A connected substrate having a supporting portion and first and second silicon carbide substrates is prepared. The first silicon carbide substrate has a first backside surface connected to the supporting portion, a first front-side surface, and a first side surface connecting the first backside surface and the first front-side surface to each other. The second silicon carbide substrate has a second backside surface connected to the supporting portion, a second front-side surface, and a second side surface connecting the second backside surface and the second front-side surface to each other and forming a gap between the first side surface and the second side surface. A filling portion for filling the gap is formed. Then, the first and second front-side surfaces are polished. Then, the filling portion is removed. Then, a closing portion for closing the gap is formed.

Abstract: A first single crystal substrate has a first side surface and it is composed of silicon carbide. A second single crystal substrate has a second side surface opposed to the first side surface and it is composed of silicon carbide. A bonding portion connects the first and second side surfaces to each other between the first and second side surfaces, and it is composed of silicon carbide. At least a part of the bonding portion has polycrystalline structure. Thus, a large-sized silicon carbide substrate allowing manufacturing of a semiconductor device with high yield can be provided.

Abstract: A silicon carbide substrate includes: a base substrate having a diameter of 70 mm or greater; and a plurality of SiC substrates made of single-crystal silicon carbide and arranged side by side on the base substrate when viewed in a planar view. In other words, the plurality of SiC substrates are arranged side by side on and along the main surface of the base substrate. Further, each of the SiC substrates has a main surface opposite to the base substrate and having an off angle of 20° or smaller relative to a {0001} plane.

Abstract: A first silicon carbide substrate has a first backside surface connected to a supporting portion, a first front-side surface opposite to the first backside surface, and a first side surface connecting the first backside surface and the first front-side surface to each other. A second silicon carbide substrate has a second backside surface connected to the supporting portion, a second front-side surface opposite to the second backside surface, and a second side surface connecting the second backside surface and the second front-side surface to each other and forming a gap between the first side surface and the second side surface. A closing portion closes the gap. Thereby, foreign matters can be prevented from remaining in a gap between a plurality of silicon carbide substrates provided in a combined substrate.

Abstract: A method for producing a silicon carbide single crystal substrate according to the present invention includes steps of: (A) preparing a silicon carbide single crystal substrate having a mechanically polished main face; (B) performing chemical mechanical polishing on the main face of the silicon carbide single crystal substrate using a polishing slurry containing abrasive grains dispersed therein to finish the main face as a mirror surface; (C?1) oxidizing at least a part of the main face finished as a mirror surface by a gas phase to form an oxide; and (C?2) removing the oxide.