Patent ID: 7759215

Claim:
A method of manufacturing a semiconductor device, comprising: (a) forming a pattern on a surface of a semiconductor substrate, said pattern including a first silicon nitride film and a cover layer formed on the first silicon nitride film, and having a window to be used for forming an isolation trench; (b) etching said semiconductor substrate by using said pattern as a mask, to form the isolation trench; (c) depositing a second silicon nitride film covering an inner surface of said isolation trench and the cover layer, wherein said first and second silicon nitride films have different etching characteristics from those of said cover layer; (d) forming a first silicon oxide film covering said second silicon nitride film and burying said isolation trench; (f) etching said first silicon oxide film to remove said first silicon oxide film in an upper region of said isolation trench, and to expose a part of the second silicon nitride film in the upper region of the isolation trench and above the surface of the semiconductor substrate; (g) etching and removing the exposed part of said second silicon nitride film, retracting an upper edge of the second silicon nitride film below the surface of the semiconductor substrate in the isolation trench, and exposing the cover layer; (h) after exposing the cover layer, forming a second silicon oxide film burying said isolation trench and covering the cover layer; (i) chemical-mechanical-polishing said second silicon oxide film and the cover layer by using said first silicon nitride film as a stopper to expose the first silicon nitride film; and (j) after chemical-mechanical polishing, etching and removing said first silicon nitride film exposed.