US4808261A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fabrication process for EPROM cells with oxide-nitride-oxide dielectric
Assignee: STMicroelectronics SRL
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Filing: 1987-04-20
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Granted: 1989-02-28
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Expires: 2007-04-20
Abstract
Abstract The process calls for covering of the dielectric with a thin additional layer of polysilicon which has the function of protecting the dielectric from any defects which would otherwise be introduced from the subsequent masking.
Inventors
- 👤 Gabriella Ghidini
- 👤 Giuseppe Crisenza
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 17:37
CPC Classifications
H; H10; H10B; H10B69/00; H10D; H10D64/00; H10D64/01; H10D64/031; H10D64/035
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
102 words
A process for fabricating EPROM cells comprising (a) depositing a dielectric with a triple oxide-nitride-oxide layer on a first layer of polysilicon laid over a substrate having a gate oxide, (b) depositing an additional layer of polysilicon on the dielectric to protect the dielectric from a protective mask, (c) applying a protective mask directly onto said additional polysilicon layer, said mask capable of covering selected portions of said dielectric, (d) removing said additional polysilicon layer and said dielectric from portions of the cell surface not protected by the mask, (e) removing said protective mask, and (f) depositing a second layer of polysilicon.
Claim 2
Dependent Claim
102 words
A process for fabricating EPROM cells comprising (a) depositing a dielectric with a triple oxide-nitride-oxide layer on a first layer of polysilicon laid over a substrate having a gate oxide, (b) depositing an additional layer of polysilicon on the dielectric to protect the dielectric from a protective mask, (c) applying a protective mask directly onto said additional polysilicon layer, said mask capable of covering selected portions of said dielectric, (d) removing said additional polysilicon layer and said dielectric from portions of the cell surface not protected by the mask, (e) removing said protective mask, and (f) depositing a second layer of polysilicon.
Claim 3
Dependent Claim
25 words
Process in accordance with claim 1, wherein said additional layer of polysilicon deposited in step (b) has a thickness on the order of 300-2000 Å.
Claim 4
Dependent Claim
19 words
Process in accordance with claim 1, wherein said dielectric has a total thickness on the order of 200-1000 Å.
Claim 5
Dependent Claim
24 words
Process in accordance with claim 3, wherein said dielectric has a top layer of oxide with a thickness on the order of 20-100 Å.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-02-28 | 1992-08-29 | 1993-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-28 | 1996-08-29 | 1997-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-28 | 2000-08-29 | 2001-02-28 | $7700.00 | Window Closed / Lapsed |