Patent ID: 7364980

Claim:
A method for manufacturing a semiconductor substrate comprising growing an epitaxial layer ( 11 ) on the surface of a silicon substrate ( 13 ), forming a trench ( 14 ) in the epitaxial layer ( 11 ), and circulating a gas to grow the epitaxial film ( 12 ) in the inside of the trench ( 14 ) and filling the inside of the trench ( 14 ) with the epitaxial film ( 12 ), wherein the aspect ratio (B/A) of the trench ( 14 ) formed in the epitaxial layer ( 11 ) is less than 10 wherein A is the width of the trench ( 14 ), and B is the depth of the trench ( 14 ), the gas is a mixed gas prepared by mixing a halogenoid gas into a silicon source gas and the gas is circulated as a material gas at least in the final step of filling the inside of the trench ( 14 ) with the epitaxial film ( 12 ), and when the standard flow rate of the halogenoid gas is defined as Xslm, and the film formation speed of the epitaxial film ( 12 ) formed by the circulation of silicon source gas is defined as Yμm/min, the following expression (1) is satisfied: Y< 0.2 X +0.10 (1).