US5318924A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nitridation of titanium-tungsten interconnects
Assignee: Avago Technologies International Sales Pte Ltd
•
Filing: 1993-01-22
•
Granted: 1994-06-07
•
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 19:37
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.
References Cited (Backward Citations)
US4429011A
Cited
US4632725A
Cited
US4701349A
Cited
US4920071A
Cited
US4676866A
Cited
US4855798A
Cited
US4782380A
Cited
US4884123A
Cited
US4994402A
Cited
US4784973A
Cited
US4787958A
Cited
US4957590A
Cited
US4847111A
Cited
US4927505A
Cited
US5047367A
Cited
US5190893A
Cited
US5164331A
Cited
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 |