Method for producing single crystal SiC substrate and single crystal SiC substrate produced by the same

A single crystal SiC substrate is produced with low cost in which a polycrystalline SiC substrate with relatively low cost is used as a base material substrate where the single crystal SiC substrate has less strain, good crystallinity and large size. The method including a P-type ion introduction step for implanting P-type ions from a side of a surface Si layer 3 into an SOI substrate 1 in which the surface Si layer 3 and an embedded oxide layer 4 having a predetermined thickness are formed on an Si base material layer 2 to convert the embedded oxide layer 4 into a PSG layer 6 to lower a softening point, and an SiC forming step for heating the SOI substrate 1 having the PSG layer 6 formed therein in an atmosphere hydrocarbon-based gas to convert the surface Si layer 3 into SiC, and thereafter, cooling the resulting substrate to form a single crystal SiC layer 5 on a surface thereof.