Patent ID: 7122443
Filing Date: 2006-10-17
Classification: H01L

Abstract:
1. A method of fabricating a flash memory device, comprising the steps of: sequentially forming a tunnel oxide film, a polysilicon film and a hard mask film on a semiconductor substrate in which a first region where the gate size is small and a second region where the gate size is great are defined; etching a predetermined region of the hard mask film, the polysilicon film and the tunnel oxide film in the second region, and then etching the semiconductor substrate at a given depth to form a first trench; forming a first wall oxide film on the first trench; forming a first insulating film on the entire surface so that the first trench is buried; etching a predetermined region of the hard mask film, the polysilicon film and the tunnel oxide film in the first region, and then etching the semiconductor substrate at a given depth to form a second trench; forming a second wall oxide film on the first trench; forming a second insulating film on the entire surface so that the second trench is buried; and polishing the first and second insulating films and then removing the hard mask film.