Claims
- 1. A method for manufacturing a semiconductor device, comprising the steps of:preparing a semiconductor substrate having an element region defined by an isolation region; forming a nitrogen-containing gate oxide film and a conductive film successively on said element region and subjecting said films to an etching selectively to form a gate electrode; forming a first dielectric film containing nitrogen to cover entirely said gate electrode and effecting an anisotropic etching to leave said first dielectric film only at a side wall of said gate electrode; implanting impurity into said semiconductor substrate to form source and drain regions; forming a second dielectric film containing nitrogen so as to cover at least said gate electrode, said first dielectric film and said source and drain regions; implanting nitrogen ions into said second dielectric film; and forming a silicon nitride film so as to cover said second dielectric film and said underlying first dielectric film and said source and drain regions to prevent outward diffusion of nitrogen from said gate electrode during subsequent thermal annealing steps.
- 2. A method as recited in claim 1, wherein said step of forming a silicon nitride film comprises forming said silicon nitride film by means of a low pressure chemical vapor deposition process.
- 3. A method as recited in claim 1, wherein said step of forming a first dielectric film comprises forming a silicon oxide film containing nitrogen by means of a chemical vapor deposition process.
- 4. A method as recited in claim 1, wherein said first dielectric film contains nitrogen in a concentration greater than that of said nitrogen-containing gate oxide film.
- 5. A method as recited in claim 1, wherein said nitrogen containing gate oxide film contains nitrogen in an amount of 3×1018−7×1018 cm−3, and said first dielectric film contains nitrogen in an amount of 5−×1018−5×1019 cm−3.
- 6. A method as recited in claim 4, wherein said first dielectric film contains nitrogen in an amount of about 1019 cm−3.
- 7. A method as recited in claim 5, wherein said first dielectric film is formed of silicon nitride.
- 8. A method as recited in claim 4, wherein said nitrogen-containing gate oxide film contains nitrogen in the amount of about 5×1018 cm−3.
Priority Claims (1)
Number |
Date |
Country |
Kind |
9-007137 |
Jan 1997 |
JP |
|
Parent Case Info
This is a divisional of application Ser. No. 09/008,941 filed on Jan. 20, 1998 now U.S. Pat. No. 5,994,749.
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