Method of manufacturing a flash memory device

Abstract

A method of manufacturing a flash memory device includes the steps of sequentially forming a tunnel oxide film and a first polysilicon layer on a semiconductor substrate in which a device separation film is formed and then patterning the tunnel oxide film and the first polysilicon layer to form a floating gate; forming a mask so that a portion in which a source region will be formed can be exposed and then removing the device separation film at the exposed portion; forming a dielectric film including a lower oxide film, a nitride film, and an upper oxide film on the entire structure; performing an annealing process; then forming a second polysilicon layer on the dielectric film; sequentially removing the polysilicon layer, the upper oxide film, and the nitride film in a portion in which a source region and a drain region will be formed, and injecting impurity ions into the semiconductor substrate at a portion in which the lower oxide film remains to form a source region and a drain region; after removing the remaining lower oxide film, sequentially forming a third polysilicon layer and a tungsten silicide layer on the entire structure and then patterning the third polysilicon layer and the tungsten silicide layer to form a control gate; and performing an annealing process for activating the impurity ions injected into the source region and the drain region.

Dependencies are inferred from the claim text.