Patent ID: 7651922

Claim:
A method for fabricating a semiconductor device, comprising: forming a first silicon nitride film on a base body; forming a silicon film on said first silicon nitride film; forming a second silicon nitride film on said silicon film; forming at least one groove extending from said second silicon nitride film to inside of said base body; forming by high-density plasma-enhanced chemical vapor deposition a silicon-containing dielectric film in said groove and on said second silicon nitride film in such a way that a silicon-rich layer is formed at a height position spaced apart from said base body within said groove, said silicon-rich layer being higher in silicon content than remaining silicon-containing dielectric film; removing by etching a portion of said silicon-containing dielectric film above said second silicon nitride film and a portion of said remaining silicon-containing dielectric film above said silicon-rich layer, if any; after having removed said silicon-containing dielectric film, removing by etching said second silicon nitride film; and after having removed said second silicon nitride film, removing by etching said silicon-rich layer and said silicon film.