Patent US6090670A successfully refreshed from Google Patents.
US6090670A
Expired / Lapsed
US
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Highly efficient transistor for fast programming of flash memories
Assignee: Micron Technology Inc
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Filing: 1997-09-05
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Granted: 2000-07-18
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Expires: 2017-09-05
Abstract
Abstract In a semiconductor fabrication method for forming a transistor structure upon a semiconductor substrate, a nitride layer is also formed over the semiconductor substrate. A gate oxide layer is formed over a region of the semiconductor substrate. The gate oxide layer has a relatively thinner oxide region over the nitride layer and a relatively thicker oxide region over the substrate adjacent the nitride layer. A transistor gate is formed extending over the relatively thinner oxide region and over the relatively thicker oxide region. The transistor thus formed is therefore asymmetric. A first transistor active region is formed in the vicinity of the relatively thicker oxide region and a second transistor active region is formed in the vicinity of the relatively thinner oxide region. The nitride layer can be formed by rapid thermal nitridization of the semiconductor substrate. The relatively thinner oxide region can be one-half as thick as the relatively thinner oxide region. The surface of the semiconductor substrate can be curved in the vicinity of the drain of the asymmetric transistor in order to permit the momentum of the charge carriers to facilitate penetration of the charge carriers into the gate.
Inventors
- 👤 Gurtej Singh Sandhu
- 👤 Pierre Fazan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:57
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/60; H10D30/68; H10D30/681; H10D30/684; H10D30/685; H10D30/6891
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
157 words
A semiconductor fabrication method for forming a transistor upon a semiconductor substrate, comprising the steps of: (a) growing a field oxide layer on said semiconductor substrate to define an area for forming said transistor, and thereby forming a sloped surface on said semiconductor substrate; (b) forming a nitride layer over said semiconductor substrate; (c) forming a gate oxide layer over said semiconductor substrate, said gate oxide layer having a relatively thinner oxide region over said nitride layer and a relatively thicker oxide region adjacent said relatively thinner oxide region, wherein said relatively thicker oxide region is formed upon said sloped surface on said semiconductor substrate; (d) forming a transistor gate extending over said relatively thinner oxide region and over said relatively thicker oxide region; (e) forming a first transistor active region in the vicinity of said relatively thicker oxide region; and (f) forming a second transistor active region in the vicinity of said relatively thinner oxide region.
Claim 2
Dependent Claim
157 words
A semiconductor fabrication method for forming a transistor upon a semiconductor substrate, comprising the steps of: (a) growing a field oxide layer on said semiconductor substrate to define an area for forming said transistor, and thereby forming a sloped surface on said semiconductor substrate; (b) forming a nitride layer over said semiconductor substrate; (c) forming a gate oxide layer over said semiconductor substrate, said gate oxide layer having a relatively thinner oxide region over said nitride layer and a relatively thicker oxide region adjacent said relatively thinner oxide region, wherein said relatively thicker oxide region is formed upon said sloped surface on said semiconductor substrate; (d) forming a transistor gate extending over said relatively thinner oxide region and over said relatively thicker oxide region; (e) forming a first transistor active region in the vicinity of said relatively thicker oxide region; and (f) forming a second transistor active region in the vicinity of said relatively thinner oxide region.
Claim 3
Dependent Claim
20 words
The semiconductor fabrication method of claim 1, wherein said field oxide layer has a thickness of approximately two thousand angstroms.
Claim 4
Dependent Claim
19 words
The semiconductor fabrication method of claim 1, wherein step (b) comprises performing rapid thermal nitridization of said semiconductor substrate.
Claim 5
Dependent Claim
15 words
The semiconductor fabrication method of claim 1, wherein step (c) comprises performing rapid thermal oxidation.
Claim 6
Dependent Claim
25 words
The semiconductor fabrication method of claim 1, wherein said relatively thicker oxide region has a thickness of between approximately 50 angstroms and approximately 150 angstroms.
Claim 7
Dependent Claim
20 words
The semiconductor fabrication method of claim 5, wherein said relatively thicker oxide region has a thickness of approximately 100 angstroms.
Claim 8
Dependent Claim
27 words
The semiconductor fabrication method of claim 1, wherein said relatively thinner oxide region has a thickness of approximately one-half the thickness of said relatively thicker oxide region.
Claim 9
Dependent Claim
23 words
The semiconductor fabrication method of claim 1, wherein said relatively thinner oxide region includes a single oxide layer disposed upon said nitride layer.
Claim 10
Dependent Claim
23 words
The semiconductor fabrication method of claim 1, wherein said relatively thinner oxide region includes oxide layers disposed upon and below said nitride layer.
Claim 11
Dependent Claim
18 words
The semiconductor fabrication method of claim 1, wherein said relatively thinner oxide region includes a layer of oxynitride.
Claim 12
Dependent Claim
24 words
The semiconductor fabrication method of claim 1, wherein step (d) comprises depositing a polysilicon layer and defining said transistor gate from said polysilicon layer.
Claim 13
Dependent Claim
19 words
The semiconductor fabrication method of claim 11, wherein said transistor gate has a thickness of approximately two thousand angstroms.
Claim 14
Dependent Claim
17 words
The semiconductor fabrication method of claim 1, wherein said first transistor active region comprises a transistor drain.
Claim 15
Dependent Claim
17 words
The semiconductor fabrication method of claim 13, wherein said second transistor active region comprises a transistor source.
Claim 16
Dependent Claim
19 words
The semiconductor fabrication method of claim 13, comprising the further step of forming a contact adjacent said transistor drain.
Claim 17
Dependent Claim
49 words
The semiconductor fabrication method of claim 15, wherein the step of forming said contact comprises the steps of depositing a layer of insulating material over said semiconductor substrate and forming an opening extending from the surface of said layer of insulating material to the surface of said semiconductor substrate.
Claim 18
Dependent Claim
25 words
The semiconductor fabrication method of claim 1, wherein said relatively thinner gate oxide region and said relatively thicker gate oxide region form an asymmetric transistor.
Claim 19
Dependent Claim
153 words
A semiconductor fabrication method for forming a transistor upon a semiconductor substrate, comprising the steps of: (a) growing a field oxide layer on said semiconductor substrate to define an area for forming said transistor, and thereby forming a sloped surface on said semiconductor substrate; (b) forming a nitride layer over said semiconductor substrate; (c) forming a gate oxide layer over said semiconductor substrate, said gate oxide layer having a relatively thinner oxide region over said nitride layer and a relatively thicker oxide region adjacent said relatively thinner oxide region, wherein said relatively thicker oxide region is self-aligned with said sloped surface; (d) forming a transistor gate extending over said relatively thinner oxide region and over said relatively thicker oxide region; (e) forming a first transistor active region in the vicinity of said relatively thicker oxide region; and (f) forming a second transistor active region in the vicinity of said relatively thinner oxide region.
Claim 20
Dependent Claim
153 words
A semiconductor fabrication method for forming a transistor upon a semiconductor substrate, comprising the steps of: (a) growing a field oxide layer on said semiconductor substrate to define an area for forming said transistor, and thereby forming a sloped surface on said semiconductor substrate; (b) forming a nitride layer over said semiconductor substrate; (c) forming a gate oxide layer over said semiconductor substrate, said gate oxide layer having a relatively thinner oxide region over said nitride layer and a relatively thicker oxide region adjacent said relatively thinner oxide region, wherein said relatively thicker oxide region is self-aligned with said sloped surface; (d) forming a transistor gate extending over said relatively thinner oxide region and over said relatively thicker oxide region; (e) forming a first transistor active region in the vicinity of said relatively thicker oxide region; and (f) forming a second transistor active region in the vicinity of said relatively thinner oxide region.
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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) | 2003-07-18 | 2004-01-17 | 2004-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-07-18 | 2008-01-17 | 2008-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-07-18 | 2012-01-17 | 2012-07-18 | $7700.00 | Window Closed / Lapsed |