Patent ID: 6509225
Filing Date: 2003-01-21
Classification: H01L

Abstract:
A method of manufacturing a semiconductor device, the method comprisinga first film forming step of successively forming, on a semiconductor substrate, a first insulating film having a relatively large thickness and a polysilicon film; a first patterning step of patterning the polysilicon film and the first insulating film to form a first-layer gate insulating film of a flash memory and a dummy gate insulating film, each being composed of the first insulating film, and to form a floating gate electrode of the flash memory and a dummy gate electrode, each being composed of the polysilicon film; a sidewall forming step of forming sidewalls on each of the floating gate electrode and the dummy gate electrode; an insulating film removing step of depositing an interlayer insulating film over the entire surface of the semiconductor substrate, removing the portions of the interlayer insulating film overlying the floating gate electrode and the dummy gate electrode, and thereby exposing the floating gate electrode and the dummy gate electrode; an etching step of forming, on the interlayer insulating film, a second insulating film covering the floating gate electrode and exposing the dummy gate electrode, performing etching by using the second insulating film to remove the dummy gate electrode and the dummy gate insulating film, and thereby forming a depressed portion internally of the sidewalls of the dummy gate electrode; a second film forming step of successively forming, over the entire surface of the semiconductor substrate, a third insulating film having a relatively small thickness and a metal film such that the depressed portion is filled therewith; and a second patterning step of patterning the second insulating film, the third insulating film, and the metal film to form a second-layer gate insulating film of the flash memory composed of the second and third insulating films, a gate insulating film of a FET composed of the third insulating film, a control electrode of the flash memory composed of the metal film, and a gate electrode of the FET composed of the metal film.