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US 2004/0002219 A1Published application
Method of forming isolation film
AssigneeFujitsu Limited
InventorKenji Sawamura
Life of this patent
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Abstract
A silicon oxide film and a silicon nitride film are formed on a silicon substrate. Then, isotropic etching is performed to the silicon nitride film by the total thickness of the silicon oxide film and a sacrifice oxide film after trenches for element isolation have been formed in the silicon substrate. Subsequently, a high-voltage operation section is covered with a resist film, and isotropic etching is performed to the silicon oxide film in a low-voltage operation section by a thickness of one gate oxide film.
Claims25
A method of forming an isolation film, comprising the steps of:
- forming a first silicon oxide film on a semiconductor substrate;
- forming a silicon nitride film on said first silicon oxide film;
- performing patterning to said silicon nitride film;
- etching said first silicon oxide film and said semiconductor substrate using said silicon nitride film as a mask and forming trenches severally in a first region and a second region of said semiconductor substrate;
- a first isotropic etching in which isotropic etching is performed to said silicon nitride film;
- a second isotropic etching in which said first region is protected by a first resist film and isotropic etching is performed to said silicon nitride film in said second region;
- removing said first resist film;
- depositing silicon oxide over the entire upper surface of said semiconductor substrate and forming a second silicon oxide film;
- removing said second silicon oxide film until said silicon nitride film exposes;
- removing said silicon nitride film;
- oxidizing the surface of said semiconductor substrate and forming a third silicon oxide film;
- a third isotropic etching in which said third silicon oxide film is removed and performing isotropic etching to said remaining second silicon oxide film;
- oxidizing the surface of said semiconductor substrate and forming a fourth silicon oxide film;
- a fourth isotropic etching in which said first region is protected by a second resist film, said fourth silicon oxide film in said second region is removed, and isotropic etching is performed to said second oxide film in said second region;
- removing said second resist film;
- and
- oxidizing the surface of said semiconductor substrate and forming a fifth silicon oxide film.
14 more elements
A method of forming an isolation film, comprising the steps of:
- forming a first silicon oxide film on a semiconductor substrate;
- forming a silicon nitride film on said first silicon oxide film;
- performing patterning to said silicon nitride film;
- etching said first silicon oxide film and said semiconductor substrate using said silicon nitride film as a mask and forming trenches severally in a first region and a second region of said semiconductor substrate;
- a first isotropic etching in which isotropic etching is performed to said silicon nitride film;
- depositing silicon oxide over the entire upper surface of said semiconductor substrate and forming a second silicon oxide film;
- removing said second silicon oxide film until said silicon nitride film exposes;
- removing said silicon nitride film;
- a second isotropic etching in which said second region is protected by a first resist film and isotropic etching is performed to said second silicon oxide film in said first region;
- removing said first resist film;
- oxidizing the surface of said semiconductor substrate and forming a third silicon oxide film;
- a third isotropic etching in which said third silicon oxide film is removed and performing isotropic etching to remaining said second silicon oxide film;
- oxidizing the surface of said semiconductor substrate and forming a fourth silicon oxide film;
- a fourth isotropic etching in which said first region is protected by a second resist film, said fourth silicon oxide film in said second region is removed, and isotropic etching is performed to said second oxide film in said second region;
- removing said second resist film;
- and
- oxidizing the surface of said semiconductor substrate and forming a fifth silicon oxide film.
14 more elements
A method of forming an isolation film, comprising the steps of:
- forming a first silicon oxide film on a semiconductor substrate;
- forming a silicon nitride film on said first silicon oxide film;
- performing patterning to said silicon nitride film and said first silicon oxide film and forming opening portions at which said semiconductor substrate exposes severally in a first region and a second region;
- forming sidewalls composed of silicon oxide on the side portions of said silicon nitride film;
- a first isotropic etching in which said second region of said semiconductor substrate is protected by a first resist film and isotropic etching is performed to said sidewalls in said first region;
- removing said first resist film;
- etching said semiconductor substrate using said silicon nitride film and said sidewalls as a mask and forming trenches severally in said first region and said second region;
- depositing silicon oxide over the entire upper surface of said semiconductor substrate and forming a second silicon oxide film;
- removing said second silicon oxide film until said silicon nitride film exposes;
- removing said silicon nitride film;
- a second isotropic etching in which said first silicon oxide film is removed and isotropic etching is performed to remaining said second silicon oxide film;
- oxidizing the surface of said semiconductor substrate and forming a third silicon oxide film;
- a third isotropic etching in which said third silicon oxide film is removed and performing isotropic etching to said second silicon oxide film;
- oxidizing the surface of said semiconductor substrate and forming a fourth silicon oxide film;
- a fourth isotropic etching in which said first region is protected by a second resist film, said fourth silicon oxide film in said second region is removed, and isotropic etching is performed to said second oxide film in said second region;
- removing said second resist film;
- and
- oxidizing the surface of said semiconductor substrate and forming a fifth silicon oxide film.
15 more elements
A method of forming an isolation film, comprising the steps of:
- forming a first silicon oxide film on a semiconductor substrate;
- forming a silicon nitride film on said first silicon oxide film;
- performing patterning to said silicon nitride film and said first silicon oxide film and forming opening portions at which said semiconductor substrate exposes severally in a first region and a second region;
- forming sidewalls composed of silicon oxide on the side portions of said silicon nitride film;
- etching said semiconductor substrate using said silicon nitride film and said sidewalls as a mask and forming trenches severally in said first region and said second region;
- depositing silicon oxide over the entire upper surface of said semiconductor substrate and forming a second silicon oxide film;
- removing said second silicon oxide film until said silicon nitride film exposes;
- removing said silicon nitride film;
- a first isotropic etching in which said first silicon oxide film is removed and isotropic etching is performed to remaining said second silicon oxide film;
- a second isotropic etching in which said second region is protected by a first resist film and isotropic etching is performed to said second silicon oxide film in said first region;
- removing said first resist film;
- oxidizing the surface of said semiconductor substrate and forming a third silicon oxide film;
- a third isotropic etching in which said third silicon oxide film is removed and performing isotropic etching to said second silicon oxide film;
- oxidizing the surface of said semiconductor substrate and forming a fourth silicon oxide film;
- a fourth isotropic etching in which said first region is protected by a second resist film, said fourth silicon oxide film in said second region is removed, and isotropic etching is performed to said second oxide film in said second region;
- removing said second resist film;
- and
- oxidizing the surface of said semiconductor substrate and forming a fifth silicon oxide film.
15 more elements
A method of forming an isolation film, comprising the steps of:
- forming a first silicon oxide film on a semiconductor substrate;
- forming a silicon nitride film on said first silicon oxide film;
- performing patterning to said silicon nitride film and said first silicon oxide film and forming an opening portion at which said semiconductor substrate exposes in a first region;
- etching said semiconductor substrate in said first region using said silicon nitride film as a mask and forming a first trench;
- a first isotropic etching in which isotropic etching is performed to said silicon nitride film;
- protecting said first region by a first resist film formed on said semiconductor substrate and etching said silicon nitride film and said first silicon oxide film on a second region of said semiconductor substrate via the opening portion of said first resist film;
- etching the second region of said semiconductor substrate via the opening portion of said first resist film and forming a second trench;
- a second isotropic etching in which isotropic etching is performed to said silicon nitride film in said second region via the opening portion of said first resist film;
- removing said first resist film;
- depositing silicon oxide over the entire upper surface of said semiconductor substrate and forming a second silicon oxide film;
- removing said second silicon oxide film until said silicon nitride film exposes;
- removing said silicon nitride film;
- a third isotropic etching in which said first silicon oxide film is removed and performing isotropic etching to remaining said second silicon oxide film;
- oxidizing the surface of said semiconductor substrate and forming a third silicon oxide film;
- a fourth isotropic etching in which said third silicon oxide film is removed, and isotropic etching is performed to said second silicon oxide film;
- oxidizing the surface of said semiconductor substrate and forming a fourth silicon oxide film;
- a fifth isotropic etching in which said second region is protected by a second resist film, said fourth silicon oxide film in said first region is removed, and isotropic etching is performed to said second silicon oxide film in said first region;
- removing said second resist film;
- and
- oxidizing the surface of said semiconductor substrate and forming a fifth silicon oxide film.
17 more elements
Dependencies are inferred from the claim text.