Method of making a MOS semiconductor device

Claim 1

A method of making a semiconductor device, comprising the steps of: providing a semiconductor substrate; forming a first insulation film on said semiconductor substrate along with insulating separating elements which are thicker than a thickness of said first insulation film; forming a first film on said first insulation film, said first film having an etching resistance which is different than said first insulation film; successively etching the first film, first insulation film, and the substrate to form a trench in the substrate, said trench having inside walls and a floor; forming a second insulation film along said inside walls and floor of said trench, said second insulation film having inside walls and a floor; forming a first electrically conductive film along said inside walls and floor of said second insulation film within said trench, said first electrically conductive film having inside walls and a floor; filling in a space defined by said inside walls and floor of said first electrically conductive film in said trench with an electrically conductive material serving as an embedded gate electrode in said trench; removing portions of the first electrically conductive film and embedded gate electrode protruding above the trench and above the first film by chemical mechanical polishing using the first film as an etching stopper; removing the first film from above the first insulation film and around upper portions of said first electrically conductive film and embedded electrode which project above the first insulation film; after removing said first thin film, forming a second electrically conductive film on the first insulation film and then conducting an etching of the second electrically conductive film so as to form respective side walls directly abutting and alongside opposite portions of the first electrically conducting film extending above said first insulation film, and selecting a thickness of said side walls for defining a distance between said shallow trench and said source and drain zones to be later provided in said substrate, edges of the source and drain zones adjacent the trench being spaced outwardly from said inside walls of said trench; and introducing impurities into said semiconductor substrate between said insulating separating elements and said trench using said embedded gate electrode and said first and second electrically conductive films as a mask to form respective source and drain zones.

Claim 2

A method of making a semiconductor device, comprising the steps of: providing a semiconductor substrate; forming a first insulation film on said semiconductor substrate along with insulating separating elements which are thicker than a thickness of said first insulation film; forming a first film on said first insulation film, said first film having an etching resistance which is different than said first insulation film; successively etching the first film, first insulation film, and the substrate to form a trench in the substrate, said trench having inside walls and a floor; forming a second insulation film along said inside walls and floor of said trench, said second insulation film having inside walls and a floor; forming a first electrically conductive film along said inside walls and floor of said second insulation film within said trench, said first electrically conductive film having inside walls and a floor; filling in a space defined by said inside walls and floor of said first electrically conductive film in said trench with an electrically conductive material serving as an embedded gate electrode in said trench; removing portions of the first electrically conductive film and embedded gate electrode protruding above the trench and above the first film by chemical mechanical polishing using the first film as an etching stopper; removing the first film from above the first insulation film and around upper portions of said first electrically conductive film and embedded electrode which project above the first insulation film; after removing said first thin film, forming a second electrically conductive film on the first insulation film and then conducting an etching of the second electrically conductive film so as to form respective side walls directly abutting and alongside opposite portions of the first electrically conducting film extending above said first insulation film, and selecting a thickness of said side walls for defining a distance between said shallow trench and said source and drain zones to be later provided in said substrate, edges of the source and drain zones adjacent the trench being spaced outwardly from said inside walls of said trench; and introducing impurities into said semiconductor substrate between said insulating separating elements and said trench using said embedded gate electrode and said first and second electrically conductive films as a mask to form respective source and drain zones.