Patent ID: RE44236

Claim:
A method for manufacturing a semiconductor device comprising the steps of: forming a trench in a semiconductor substrate; and forming an epitaxial film on the substrate including a sidewall and a bottom of the trench so that the epitaxial film is filled in the trench, wherein the step of forming the epitaxial film includes a final step before the trench is filled with the epitaxial film, the final step has a forming condition of the epitaxial film in such a manner that a mixture of a silicon source gas and a halogenide gas is used for forming the epitaxial film, the step of forming the epitaxial film further includes a first step, the first step is such that the epitaxial film having an impurity doped in the epitaxial film is formed on the bottom and the sidewall of the trench to have a predetermined thickness, the final step is such that the epitaxial film having no impurity doped or a low concentration impurity doped in the epitaxial film is formed to fill an inside of the trench, and the low concentration impurity of the epitaxial film in the final step has an impurity concentration lower than that in the first step.