Patent US6720610B2 successfully refreshed from Google Patents.
US6720610B2
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Nonvolatile semiconductor memory device and its manufacturing method
Assignee: Toshiba Corp
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Filing: 2000-12-11
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Granted: 2004-04-13
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Expires: 2020-12-11
Abstract
Abstract A non-volatile semiconductor memory device, which is intended to prevent data destruction by movements of electric charges between floating gates and thereby improve the reliability, includes element isolation/insulation films buried into a silicon substrate to isolate stripe-shaped element-forming regions. Formed on the substrate area floating gate via a first gate insulating film and further a control gate via a second gate insulating film. Source and drain diffusion layers are formed in self-alignment with control gates. The second gate insulating film on the floating gate is divided and separated together with the floating gate by slits above the element isolation/insulation films into discrete portions of individual memory cells.
Inventors
- 👤 Tadashi Iguchi
- 👤 Yoshiaki Himeno
- 👤 Hiroaki Tsunoda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:12
CPC Classifications
H; H10; H10B; H10B41/00; H10B41/30; H10B41/35; H10B69/00; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/0411
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
157 words
A nonvolatile semiconductor memory device comprising: a semiconductor substrate; a plurality of element-forming regions partitioned by element isolation/insulation films in said semiconductor substrate; floating gates formed in said element-forming regions via a first gate insulating film and separated for individual of said element-forming regions, a level of a top surface of said first gate insulating film being lower than a level of a top surface of said element isolation/insulation film and a part of said floating gates reaching a side surface of said element isolation/insulation films; a second gate insulating film formed on said floating gates, at least a part of said second gate insulating film reaching a top surface of said element isolation/insulation films; control gates formed on said floating gates by said second gate insulating films; and source and drain diffusion layers formed in self-alignment with said control ages, wherein said second gate insulating film is divided and separated only above said element isolation/insulation films.
Claim 2
Dependent Claim
157 words
A nonvolatile semiconductor memory device comprising: a semiconductor substrate; a plurality of element-forming regions partitioned by element isolation/insulation films in said semiconductor substrate; floating gates formed in said element-forming regions via a first gate insulating film and separated for individual of said element-forming regions, a level of a top surface of said first gate insulating film being lower than a level of a top surface of said element isolation/insulation film and a part of said floating gates reaching a side surface of said element isolation/insulation films; a second gate insulating film formed on said floating gates, at least a part of said second gate insulating film reaching a top surface of said element isolation/insulation films; control gates formed on said floating gates by said second gate insulating films; and source and drain diffusion layers formed in self-alignment with said control ages, wherein said second gate insulating film is divided and separated only above said element isolation/insulation films.
Claim 3
Dependent Claim
29 words
The nonvolatile semiconductor memory device according to claim 1 , wherein each said second gate insulating film is a multi-layered film including silicon oxide film/silicon nitride film/silicon oxide film.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2007-04-13 | 2007-10-13 | 2008-04-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2011-04-13 | 2011-10-13 | 2012-04-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2015-04-13 | 2015-10-13 | 2016-04-13 | $7700.00 | Window Closed / Lapsed |