PURPOSE: To enhance an epitaxial film in uniformity of resistivity and to lessen a carrier concentration profile on a high impurity concentration buried layer in protrusion height by a method wherein impurity ion implantation and a heat treatment are carried out after an epitaxial growth operation is executed.

CONSTITUTION: A non-doped silicon epitaxial film 3 as thick as 1μm or below is grown on a silicon substrate 1 provided with a high concentration Sb buried layer 2, P+ ions 4 are implanted into the, epitaxial film 3, and the substrate 1 is thermally treated in an adequate atmosphere of N2-O2. By implanting P+ ion, all the surface of the epitaxial film 3 is uniformly doped with P+ ion, and Sb is restrained from protruding into the epitaxial film 3 from the high concentration Sb buried layer 2 by devising thermal treatment conditions.