Patent ID: 7018927

Claim:
A method for forming an isolation film for semiconductor devices, the method comprising the steps of: successively forming a pad oxide film and a pad nitride film on a silicon substrate having an active region and a field region; etching the pad nitride film, the pad oxide film and the silicon substrate to form a trench in the active region of the substrate; forming a sidewall oxide film on the surface of the trench; removing the pad nitride film; forming a linear nitride film on the sidewall oxide film and the pad oxide film; subjecting the linear nitride film to CMP such that a portion of the pad oxide film on the field region of the substrate is exposed; removing the exposed pad oxide film to expose the field region of the substrate; oxidizing the exposed field region of the substrate to form an oxide film to the same depth as the bottom of the trench; removing the linear nitride film; removing the sidewall oxide film to expose the active region of the substrate; and forming a silicon epitaxial layer serving as an active layer on the exposed active region of the substrate to the same height as the oxide film.