Patent ID: 7091105

Claim:
A method of forming an isolation film in a semiconductor device, comprising: forming a stack structure of a pad oxide film and a photoresist pattern on a semiconductor substrate on which an isolation region is defined, the isolation region having one or more comers and a central portion, the photoresist pattern containing silicon; implementing an over etch so that polymer is formed at the corners of the isolation region to form an etch slant face at one or more corners of the isolation region while etching the semiconductor substrate at the central portion of the isolation region; forming a trench at the central portion of the isolation region; oxidizing a surface of the photoresist pattern to form a surface oxide film; forming an insulating material layer on the entire structure to bury the trench; and implementing a polishing process until the photoresist pattern has a given thickness and then removing the photoresist pattern and the pad oxide film.