Patent ID: 6962856

Claim:
A method for forming a device isolation film, comprising the steps of: (a) sequentially forming a pad oxide film and a pad nitride film on a semiconductor substrate; (b) selectively etching the pad nitride film to form a nitride film pattern; (c) etching the pad oxide film and a predetermined thickness of the semiconductor substrate using the nitride film pattern as a hard mask to form a trench; (d) forming a thermal oxide film on the surface of the trench; (e) performing an annealing process under NH 3 atmosphere to form an oxide nitride film on the surface of the thermal oxide film; (f) forming a liner nitride film on the oxide nitride film and the pad nitride film to improve interface characteristic between the thermal oxide film and said liner nitride film; (g) forming an oxide film filling the trench on the entire surface; and (h) performing a planarization process.