US5318924A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nitridation of titanium-tungsten interconnects
Assignee: Avago Technologies International Sales Pte Ltd
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Filing: 1993-01-22
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Granted: 1994-06-07
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Expires: 2013-01-22
Abstract
Abstract A method of forming interconnects for submicron integrated circuits that allows use of titanium-tungsten as the interconnect material. The inherent instability of titanium-tungsten to oxidation is addressed by a nitridation process that includes exposing the interconnect to an ambient containing nitrogen (NH 3 ) at an elevated temperature. Typically, the process is a rapid thermal anneal. A local interconnect may be formed, whereafter an insulating layer can be deposited at a high temperature without causing oxidation within the local interconnect that would adversely affect the resistivity of the material.
Inventors
- 👤 Jung Lin
- 👤 John E. Turner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:44
CPC Classifications
H; H10; H10W; H10W20/00; H10W20/01; H10W20/031; H10W20/0698
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
151 words
A method of providing a single-layer local interconnect within an integrated circuit comprising, providing a semiconductor wafer having spaced apart first and second electrode regions, forming a layer of titanium atop said semiconductor wafer, heating said semiconductor wafer, whereby first surface portions of said titanium react to form a silicide and second surface portions of said titanium remain unreacted, removing said second surface portions of said titanium, leaving said silicide, depositing a titanium-tungsten layer on said semiconductor wafer such that said titanium-tungsten contacts said silicide, patterning said titanium-tungsten layer such that a single-layer local interconnect is formed from said first electrode region to said second electrode region, nitriding said patterned titanium-tungsten layer, including heating said patterned titanium-tungsten layer and exposing said patterned titanium-tungsten layer to an ambient containing ammonia, thereby forming a nitrided titanium-tungsten interconnect, and depositing an insulator layer on said titanium-tungsten interconnect, whereby a single-layer local interconnect is formed.
Claim 2
Independent Claim
151 words
A method of providing a single-layer local interconnect within an integrated circuit comprising, providing a semiconductor wafer having spaced apart first and second electrode regions, forming a layer of titanium atop said semiconductor wafer, heating said semiconductor wafer, whereby first surface portions of said titanium react to form a silicide and second surface portions of said titanium remain unreacted, removing said second surface portions of said titanium, leaving said silicide, depositing a titanium-tungsten layer on said semiconductor wafer such that said titanium-tungsten contacts said silicide, patterning said titanium-tungsten layer such that a single-layer local interconnect is formed from said first electrode region to said second electrode region, nitriding said patterned titanium-tungsten layer, including heating said patterned titanium-tungsten layer and exposing said patterned titanium-tungsten layer to an ambient containing ammonia, thereby forming a nitrided titanium-tungsten interconnect, and depositing an insulator layer on said titanium-tungsten interconnect, whereby a single-layer local interconnect is formed.
Claim 3
Dependent Claim
26 words
The method of claim 1 wherein said step of nitriding includes rapid thermal annealing at a temperature in the range of 600° C. to 900° C.
Claim 4
Dependent Claim
42 words
The method of claim 2 wherein said step of nitriding includes directing said ambient containing ammonia to said titanium-tungsten layer at a flow rate in the range of 3-10 liters/min and for a period in the range of 30 to 90 seconds.
Claim 5
Independent Claim
124 words
A method of forming a local interconnect in a semiconductor integrated circuit comprising, providing a semiconductor wafer having a plurality of electrode regions thereon, depositing a layer of titanium over said electrode regions, forming a silicide on said electrode regions, depositing an interconnect layer of titanium-tungsten on said semiconductor wafer, including depositing said interconnect layer directly onto said silicide, patterning said interconnect layer, including leaving a single-layer local interconnect extending from a first electrode region to a second electrode region, exposing said local interconnect to a heated ammonia-containing ambient, thereby forming at least a portion of said local interconnect into a nitrided titanium-tungsten local layer, and coating said local interconnect with an insulating layer, said insulating layer being deposited directly onto said local interconnect.
Claim 6
Independent Claim
124 words
A method of forming a local interconnect in a semiconductor integrated circuit comprising, providing a semiconductor wafer having a plurality of electrode regions thereon, depositing a layer of titanium over said electrode regions, forming a silicide on said electrode regions, depositing an interconnect layer of titanium-tungsten on said semiconductor wafer, including depositing said interconnect layer directly onto said silicide, patterning said interconnect layer, including leaving a single-layer local interconnect extending from a first electrode region to a second electrode region, exposing said local interconnect to a heated ammonia-containing ambient, thereby forming at least a portion of said local interconnect into a nitrided titanium-tungsten local layer, and coating said local interconnect with an insulating layer, said insulating layer being deposited directly onto said local interconnect.
Claim 7
Dependent Claim
34 words
The method of claim 4 wherein said step of exposing is a step of rapid thermal annealing said local interconnect in a flow of ammonia, said flow being free of gases other than ammonia.
Claim 8
Dependent Claim
39 words
The method of claim 4 wherein said step of patterning includes leaving said local interconnect along an electrical path from a first electrode region and atop a field oxide region of said semiconductor wafer to a second electrode region.
Claim 9
Dependent Claim
20 words
The method of claim 4 wherein said step of forming said silicide is a step of forming self-aligned titanium disilicide.
Claim 10
Dependent Claim
20 words
The method of claim 4 wherein said step of depositing said interconnect layer is a step of sputter depositing titanium-tungsten.
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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) | 1997-06-06 | 1997-12-06 | 1998-06-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-06-06 | 2001-12-06 | 2002-06-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-06-06 | 2005-12-06 | 2006-06-07 | $7700.00 | Window Closed / Lapsed |