Method for forming isolation region in semiconductor device

摘要

Disclosed is a method for forming an isolation region in a semiconductor device. Pad oxide and nitride films are sequentially formed on a silicon substrate. Photoresist pattern is formed on the pad nitride film, the photoresist pattern. Respectively predetermined parts of the pad oxide and nitride films and the silicon substrate are etched by using the photoresist pattern as a mask to form a shallow trench. Field implant process is performed on a lower surface of the shallow trench, by using the photoresist pattern as a mask to form a field stop implant film. Photoresist pattern is removed. The inside of the shallow trench is washed. The inside of the shallow trench is thermally enlarged to form a first oxide film. Second oxide film is deposited on the first oxide film and chemical mechanical polishing process for the second oxide film is performed to form the isolation region.