Fabrication of element isolation film of semiconductor device is fabricated by using aluminum oxide film of high wet etch rate as pad oxide film, and making edges of trench rounded while removing some of the oxide film by cleaning

摘要

An element isolation film of a semiconductor device is fabricated by using an aluminum oxide film of a high wet etch rate as a pad oxide film, forming a trench, and making the top and bottom edges of the trench rounded while removing some of the aluminum oxide film by a cleaning process. Formation of an element isolation film of a semiconductor device involves: (a) forming a pad oxide film and a pad nitride film on a semiconductor substrate (11); (b) etching a region of the pad nitride film (13) and the pad oxide film (12) and then etching the semiconductor substrate to form a trench (15); (c) performing a cleaning process to make top and bottom edges of the trench rounded while removing a portion of the pad oxide film; (d) forming an oxide film (16) on the entire surface so that the trench is buried; and (e) polishing the oxide film and then removing the oxide film, the pad nitride film, and the pad oxide film.