Patent US5843826A successfully refreshed from Google Patents.
US5843826A
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US
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Deep submicron MOSFET device
Assignee: United Microelectronics Corp
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Filing: 1997-08-27
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Granted: 1998-12-01
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Expires: 2017-08-27
Abstract
Abstract A FET is formed that occupies a reduced surface area on a substrate because it incorporates elevated source/drain contacts provided at least partially over the field oxide regions. A silicon nitride mask is formed over the substrate and the mask is used for defining field oxide regions. Trenches are etched on either side of the mask and then thermal oxidation grows field oxide regions in the trenches so that the surface of the field oxide regions are approximately even with the original surface of the substrate. With the silicon nitride mask still in place, polysilicon is deposited over the substrate. The device is then planarized to remove the polysilicon from surfaces of the substrate, exposing the surface of the mask and leaving polysilicon structures on the field oxide regions on either side of mask. The mask is stripped and a layer of silicon is deposited over the polysilicon structures and on the active device region of the substrate, where the deposited silicon is epitaxial. A gate oxide layer is formed by oxidation of the epitaxial silicon and then a gate electrode is formed. The gate electrode can be spaced closer to the field oxide regions than is typically possible because contacts to the source/drain regions of the FET are formed through the first and second conductive structures.
Inventors
- 👤 Gary Hong
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 14:17
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/10; H10D62/13; H10D62/149; H10D62/151; H10D30/00; H10D30/01; H10D30/021; H10D30/027; H10D30/0278; H10D62/17; H10D62/213; H10D62/221; H10D62/235; H10D62/292; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10D64/20; H10D64/23; H10D64/251; H10D64/258
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
276 words
A method of forming an integrated circuit device comprising the steps of: providing a substrate having first and second insulating device isolation structures on a surface of the substrate, a portion of the surface of the substrate between the first and second insulating device isolation structures providing at least a portion of an active device region for the integrated circuit device; forming first and second conductive structures on the corresponding first and second device isolation structures; depositing a layer of silicon material over the active device region and connecting the first and second conductive structures to portions of the active device region; forming a gate oxide layer and a gate electrode on the layer of silicon over the active device region, the gate electrode positioned at least partially between the first and second conductive structures; and forming first and second source/drain regions at least partially within the layer of silicon over the active device region, the first and second conductive structures electrically connected to and providing contacts for the respective first and second source/drain regions; wherein the device isolation structures are provided by forming a mask over the substrate and providing insulating device isolation regions aligned with first and second edges of the mask; and wherein the step of forming first and second conductive structures includes the steps of: depositing a polysilicon layer over surfaces of the first and second insulating device isolation regions and over the mask; and planarizing the polysilicion layer so that the polysilicon layer is removed from over the mask and first and second polysilicon structures extend over the first and second insulating device isolation structures on either side of the mask.
Claim 2
Independent Claim
276 words
A method of forming an integrated circuit device comprising the steps of: providing a substrate having first and second insulating device isolation structures on a surface of the substrate, a portion of the surface of the substrate between the first and second insulating device isolation structures providing at least a portion of an active device region for the integrated circuit device; forming first and second conductive structures on the corresponding first and second device isolation structures; depositing a layer of silicon material over the active device region and connecting the first and second conductive structures to portions of the active device region; forming a gate oxide layer and a gate electrode on the layer of silicon over the active device region, the gate electrode positioned at least partially between the first and second conductive structures; and forming first and second source/drain regions at least partially within the layer of silicon over the active device region, the first and second conductive structures electrically connected to and providing contacts for the respective first and second source/drain regions; wherein the device isolation structures are provided by forming a mask over the substrate and providing insulating device isolation regions aligned with first and second edges of the mask; and wherein the step of forming first and second conductive structures includes the steps of: depositing a polysilicon layer over surfaces of the first and second insulating device isolation regions and over the mask; and planarizing the polysilicion layer so that the polysilicon layer is removed from over the mask and first and second polysilicon structures extend over the first and second insulating device isolation structures on either side of the mask.
Claim 3
Dependent Claim
21 words
The method of claim 1, wherein the mask comprises silicon nitride and the polysilicon layer is planarized by chemical mechanical polishing.
Claim 4
Dependent Claim
34 words
The method of claim 2, wherein the first and second insulating device isolation structures are formed by forming trenches in the substrate on either side of the mask and filling the trenches with oxide.
Claim 5
Dependent Claim
13 words
The method of claim 3, wherein the trenches are filled by thermal oxidation.
Claim 6
Dependent Claim
12 words
The method of claim 3, wherein the trenches are formed by etching.
Claim 7
Dependent Claim
18 words
The method of claim 1, wherein the layer of silicon is provided in a selective epitaxial growth process.
Claim 8
Dependent Claim
25 words
The method of claim 6, wherein the layer of silicon comprises epitaxial silicon on the active device region and polysilicon deposited over the conductive structures.
Claim 9
Dependent Claim
19 words
The method of claim 7, wherein the gate oxide layer is grown by thermal oxidation of the epitaxial silicon.
Claim 10
Dependent Claim
66 words
The method of claim 6, wherein the layer of silicon is doped by ion implantation after the gate electrode is provided, so that portions of the conductive layer provided over the first and second conductive structures are comparatively heavily doped to a first conductivity type and a portion of the conductive layer provided under the gate electrode is comparatively lightly doped to a second conductivity type.
Claim 11
Dependent Claim
46 words
The method of claim 6, wherein portions of the layer of silicon in contact with the first and second conductive structures are converted to metal silicide while a portion of the layer of silicon over the active device region is not converted to a metal silicide.
Claim 12
Dependent Claim
12 words
The method of claim 10, wherein the metal silicide is titanium silicide.
Claim 13
Dependent Claim
43 words
The method of claim 1, further comprising the steps of: depositing a layer of insulating material over the first and second conductive structures; and etching a contact opening through the layer of insulating material to expose a surface of the first conductive structure.
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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) | 2001-11-30 | 2002-06-01 | 2002-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-11-30 | 2006-06-01 | 2006-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-11-30 | 2010-06-01 | 2010-12-01 | $7700.00 | Window Closed / Lapsed |