A process for producing a semiconductor substrate

A process for producing a semiconductor substrate comprising: (A) a step of growing a first epitaxial film (61) on the surface of a substrate body (63); (B) a step of partially etching the first epitaxial film (61) to form a plurality of first trenches (64) with a depth B and a width A; (C) a step of growing a second epitaxial film (62) throughout the interior of the plurality of the first trenches (64) and on the surface of the first epitaxial film (61) except the plurality of first trenches (64); (D) a step of polishing of the second epitaxial film (62) for exposing the surface of the first epitaxial film (61) and leveling the upper side of the second epitaxial film (62) buried in the entire interior of the plurality of first trenches (64) ; (E) a step of further growing a third epitaxial film (66) having the same composition as that of the first epitaxial film ...