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US5312781A
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US
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Flash EEPROM fabrication process that uses a selective wet chemical etch
Assignee: Nokia Bell Labs
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Filing: 1991-11-12
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Granted: 1994-05-17
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Expires: 2011-11-12
Abstract
Abstract A method for wet etching disposable spacers in silicon integrated circuits is provided. Illustratively, a pair of spacers is formed over a polysilicon substrate. A second pair of spacers is formed from doped silicon dioxide over the first pair of spacers. Then the second pair of spacers is etched away with NH 4 OH/H 2 O 2 , thus providing a means for defining the underlying polysilicon layer, e.g., by etching.
Inventors
- 👤 Richard W. Gregor
- 👤 Chung W. Leung
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:56
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283; Y; Y10; Y10S; Y10S438/00; Y10S438/978
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
40 words
A method of fabricating a semiconductor device comprising: forming a first dielectric layer of BPTEOS overlying polysilicon substrate; wet etching said first dielectric layer; CHARACTERIZED IN THAT said wet etching is accomplished with NH 4 OH/H 2 O 2 .
Claim 2
Independent Claim
40 words
A method of fabricating a semiconductor device comprising: forming a first dielectric layer of BPTEOS overlying polysilicon substrate; wet etching said first dielectric layer; CHARACTERIZED IN THAT said wet etching is accomplished with NH 4 OH/H 2 O 2 .
Claim 3
Dependent Claim
19 words
The method of claim 1 in which a second dielectric is formed between said first dielectric and said substrate.
Claim 4
Dependent Claim
13 words
The method of claim 2 in which said second dielectric layer is TEOS.
Claim 5
Dependent Claim
19 words
The method of claim 1 in which said wet etching is carried out at a temperature of 87°±3° C.
Claim 6
Dependent Claim
28 words
The method of claim 2 in which said second dielectric layer comprises a first spacer and said first dielectric layer comprises a second spacer overlying said first spacer.
References Cited (Backward Citations)
US4113551A
Cited
US4652334A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-05-16 | 1997-11-15 | 1998-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-05-16 | 2001-11-15 | 2002-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-05-16 | 2005-11-15 | 2006-05-17 | $7700.00 | Window Closed / Lapsed |