Patent ID: 7811907

Claim:
A method for manufacturing a semiconductor device comprising steps of: forming a trench on a main surface of a silicon substrate; forming a first epitaxial film on the main surface of the silicon substrate and in the trench by using a mixed gas of a silicon source gas and a halide gas so that the trench is filled with the first epitaxial film; and forming a second epitaxial film on the first epitaxial film by using another mixed gas of the silicon source gas and the halide gas, wherein the step of forming the first epitaxial film has a first process condition with a first growth rate of the first epitaxial film growing on the main surface of the silicon substrate, wherein the step of forming the second epitaxial film has a second process condition with a second growth rate of the second epitaxial film growing on the main surface of the silicon substrate, wherein the second growth rate of the second epitaxial film is larger than the first growth rate of the first epitaxial film, wherein in the step of forming the first epitaxial film, the halide gas is flown with a standard flow rate, which defined as X in slm unit, and the first epitaxial film is grown with a growth rate, which is defined as Y in unit of micron per minute, wherein the trench has an aspect ratio larger than 10, and the standard flow rate of the halide gas and the growth rate of the first epitaxial film has a relationship of: Y< 0.2 X +0.1.