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US5502009A
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Method for fabricating gate oxide layers of different thicknesses
Assignee: United Microelectronics Corp
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Filing: 1995-02-16
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Granted: 1996-03-26
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Expires: 2015-02-16
Abstract
Abstract A method for fabricating gate oxide layers of different thicknesses on a silicon substrate. A field oxide layer is formed on a predetermined portion of the silicon substrate to define first active regions and second active regions. A first gate oxide layer is formed over the first and second active regions. A barrier layer is formed to cover a portion of the first gate oxide layer within the first active regions. The portion of the first gate oxide layer within the second active regions is then removed utilizing the barrier layer as masking. A second gate oxide layer is then formed over the second active regions.
Inventors
- 👤 Jengping Lin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:57
CPC Classifications
H; H10; H10D; H10D84/00; H10D84/01; H10D84/0123; H10D84/0126; H10D84/0144; H10D84/02; H10D84/03; H10D84/038; Y; Y10; Y10S; Y10S438/00; Y10S438/981
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
119 words
A method for fabricating gate oxide layers of different thicknesses on a silicon substrate comprising the steps of: (a) forming a field oxide layer on said substrate to define a plurality of first active regions and second active regions therebetween; (b) forming a first gate oxide layer over said plurality of first active regions and said second active regions; (c) forming a silicon nitride layer onto an overall surface; (d) patterning and etching said silicon nitride layer to remove a portion of said silicon nitride layer within said second active regions; (e) removing a portion of said first gate oxide layer within said second active regions; and (f) forming a second gate oxide layer over said second active regions.
Claim 2
Independent Claim
119 words
A method for fabricating gate oxide layers of different thicknesses on a silicon substrate comprising the steps of: (a) forming a field oxide layer on said substrate to define a plurality of first active regions and second active regions therebetween; (b) forming a first gate oxide layer over said plurality of first active regions and said second active regions; (c) forming a silicon nitride layer onto an overall surface; (d) patterning and etching said silicon nitride layer to remove a portion of said silicon nitride layer within said second active regions; (e) removing a portion of said first gate oxide layer within said second active regions; and (f) forming a second gate oxide layer over said second active regions.
Claim 3
Dependent Claim
20 words
The method of claim 1, wherein said silicon nitride layer has a thickness ranging between 100 Å to 1000 Å.
Claim 4
Dependent Claim
15 words
The method of claim 1, wherein the step (d) is performed by reactive ion etching.
Claim 5
Dependent Claim
49 words
The method of claim 1, wherein the step of forming said first gate oxide layer and the step of forming said second gate oxide layer each include the step of performing dry oxidation at a temperature range of 750° C. to 1000° C. for 10 minutes to 2 hours.
Claim 6
Dependent Claim
49 words
The method of claim 1, wherein the step of forming said first gate oxide layer and the step of forming said second gate oxide layer each include the step of performing wet oxidation at a temperature range of 750° C. to 1000° C. for 10 minutes to 2 hours.
Claim 7
Dependent Claim
24 words
The method of claim 1, further comprising, between step (a) and (b), the step of performing an implantation process for adjusting the threshold voltage.
Claim 8
Dependent Claim
14 words
The method of claim 1, wherein the step (e) is performed by hydrofluoric acid.
Claim 9
Independent Claim
148 words
A method for fabricating gate oxide layers of different thicknesses on a silicon substrate comprising the steps of: (a) forming a field oxide layer on said substrate to define a plurality of first active regions and second active regions therebetween; (b) forming a first gate oxide layer over said plurality of first active regions and said second active regions; (c) forming a silicon nitride layer onto an overall surface; (d) forming a silicon oxide layer over said silicon nitride layer; (e) removing a portion of said silicon oxide layer within said second active regions; (f) etching said silicon nitride layer to remove a portion of said silicon nitride layer within said second active regions; (g) removing said silicon oxide layer; (h) removing a portion of said first gate oxide layer within said second active regions; and (i) forming a second gate oxide layer over said second active regions.
Claim 10
Independent Claim
148 words
A method for fabricating gate oxide layers of different thicknesses on a silicon substrate comprising the steps of: (a) forming a field oxide layer on said substrate to define a plurality of first active regions and second active regions therebetween; (b) forming a first gate oxide layer over said plurality of first active regions and said second active regions; (c) forming a silicon nitride layer onto an overall surface; (d) forming a silicon oxide layer over said silicon nitride layer; (e) removing a portion of said silicon oxide layer within said second active regions; (f) etching said silicon nitride layer to remove a portion of said silicon nitride layer within said second active regions; (g) removing said silicon oxide layer; (h) removing a portion of said first gate oxide layer within said second active regions; and (i) forming a second gate oxide layer over said second active regions.
Claim 11
Dependent Claim
20 words
The method of claim 8, wherein said silicon oxide layer has a thickness ranging between 50 Å and 1000 Å.
Claim 12
Dependent Claim
20 words
The method of claim 8, wherein said silicon nitride layer has a thickness ranging between 100 Å to 1000 Å.
Claim 13
Dependent Claim
14 words
The method of claim 8, wherein the step (f) is performed by phosphoric acid.
Claim 14
Dependent Claim
49 words
The method of claim 8, wherein the step of forming said first gate oxide layer and the step of forming said second gate oxide layer each include the step of performing dry oxidation at a temperature range of 750° C. to 1000° C. for 10 minutes to 2 hours.
Claim 15
Dependent Claim
49 words
The method of claim 8, wherein the step of forming said first gate oxide layer and the step of forming said second gate oxide layer each include the step of performing wet oxidation at a temperature range of 750° C. to 1000° C. for 10 minutes to 2 hours.
Claim 16
Dependent Claim
24 words
The method of claim 8, further comprising between step (a) and (b), the step of performing an implantation process for adjusting the threshold voltage.
Claim 17
Dependent Claim
13 words
The method of claim 8, wherein step (h) is performed by hydrofluoric acid.
References Cited (Backward Citations)
US4859619A
Cited
US5254489A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1999-03-26 | 1999-09-25 | 2000-03-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-03-26 | 2003-09-25 | 2004-03-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-03-26 | 2007-09-25 | 2008-03-26 | $7700.00 | Window Closed / Lapsed |