Method for manufacturing SiC composite substrate, and method for manufacturing semiconductor substrate

A method for manufacturing an SiC composite substrate having a single-crystal SiC layer on a polycrystalline SiC substrate, comprising:

• providing a single-crystal SiC layer on one surface of a holding substrate made of Si to prepare a single-crystal SiC layer carrier, thereafter
• (i) causing warp in the single-crystal SiC layer carrier by applying physical damage to a surface opposite to the single-crystal SiC layer-carrying surface of the holding substrate in the single-crystal SiC layer carrier, and then depositing polycrystalline SiC on the single-crystal SiC layer by a physical or chemical means to prepare an SiC laminate in which the single-crystal SiC layer and the polycrystalline SiC substrate are laminated on the holding substrate, or
• (ii) depositing polycrystalline SiC on the single-crystal SiC layer by physical or chemical means to prepare an SiC laminate in which the single-crystal SiC layer and the polycrystalline SiC substrate are laminated on the holding substrate, and then applying physical damage to a surface opposite to a surface of the polycrystalline SiC substrate abutting with the single-crystal SiC layer in the SiC laminate to prepare an SiC laminate in which the single-crystal SiC layer and the polycrystalline SiC substrate are laminated on the holding substrate,
• and thereafter
• removing the holding substrate physically and/or chemically.