Formation of wall oxide films in flash memory device by performing oxidation process in gas atmosphere comprising hydrogen and oxygen in in-situ steam generation oxidation mode

摘要

Formation of wall oxide films in flash memory device includes providing a semiconductor substrate in which trenches are formed, and performing an oxidation process in a gas atmosphere comprising hydrogen and oxygen in an in-situ steam generation (ISSG) oxidation mode to form wall oxide films on sidewalls of the trenches. An independent claim is also included for formation of isolation film in a flash memory device by providing a semiconductor substrate (10) in which a pad oxide film (11a) is formed; depositing a pad nitride film (12) on the pad oxide film; etching the pad nitride film and pad oxide film, and contemporaneously recessing some of a top of the substrate to form first trenches; forming spacers (16a) on the sidewalls of first trenches; performing first oxidation process in ISSG oxidation mode in a gas atmosphere comprising hydrogen and oxygen to oxidize the top of semiconductor substrate which is exposed between the spacers; etching the semiconductor substrate through the first trenches to form second trenches; performing a second oxidation process in ISSG oxidation mode in a gas atmosphere comprising hydrogen and oxygen to form wall oxide films (18) on sidewalls of the second trenches; and forming an isolation film to fill the second trenches.