Patent US4502209A successfully refreshed from Google Patents.
US4502209A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Forming low-resistance contact to silicon
Assignee: Nokia Bell Labs
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Filing: 1983-08-31
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Granted: 1985-03-05
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Expires: 2003-08-31
Abstract
Abstract Annealing a titanium-rich carbide film deposited on silicon produces, in a single processing step, both a stable titanium silicide contact and a titanium carbide diffusion barrier between the silicide and a subsequently formed overlying layer of aluminum. Reliable low-resistance contacts to VLSI devices are thereby provided in a cost-effective fabrication sequence. Other metallization systems, comprising a silicide and a diffusion barrier to aluminum formed in a single processing step, are also described.
Inventors
- 👤 Moshe Eizenberg
- 👤 Shyam P. Murarka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:28
CPC Classifications
H; H10; H10W; H10W20/00; H10W20/01; H10W20/031; H10W20/032; H10W20/033; H10D; H10D62/00; H10D62/80; H10D62/83; H10D64/00; H10D64/01; H10D64/011; H10D64/0111; H10D64/0112; H10D64/60; H10D64/62; H10W20/40; H10W20/41; H10W20/425
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
103 words
A method of making a semiconductor device, comprising the steps of depositing a film of A x B on a surface of a device structure that includes silicon surface regions, where A is selected from the group consisting of titanium, hafnium, zirconium, tantalum and niobium, and B is selected from the group consisting of carbon, nitrogen and boron, and heating said structure to convert those portions of the film that overlie silicon surface regions into a two-layer metallization comprising a layer of ASi 2 and an overlying layer of A y B, where x is both greater than one and greater than y.
Claim 2
Independent Claim
103 words
A method of making a semiconductor device, comprising the steps of depositing a film of A x B on a surface of a device structure that includes silicon surface regions, where A is selected from the group consisting of titanium, hafnium, zirconium, tantalum and niobium, and B is selected from the group consisting of carbon, nitrogen and boron, and heating said structure to convert those portions of the film that overlie silicon surface regions into a two-layer metallization comprising a layer of ASi 2 and an overlying layer of A y B, where x is both greater than one and greater than y.
Claim 3
Dependent Claim
39 words
A method as in claim 1 wherein 1<x<5, and further comprising depositing a layer of aluminum on said film, and correspondingly patterning said layer and unconverted portions of said underlying film to form composite-metallization electrical connections in said device.
Claim 4
Dependent Claim
13 words
A method as in claim 2 wherein said film comprises Ti x C.
Claim 5
Dependent Claim
64 words
A method as in claim 3 wherein said film is deposited in a reactive radio-frequency sputtering system in an argon-methane gas mixture in which the methane molar percentage in the mixture is in the range of about 0.1-to-6, the total sputtering gas pressure is in the range of about 5-to-20 milliTorr and the radio-frequency power in the system is maintained at about 200-to-800 watts.
Claim 6
Dependent Claim
40 words
A method as in claim 4 wherein the heating step is carried out at a temperature in the range of approximately 600-to-900 Celsius for one-half-to-one hour in a vacuum or in an oxygen-free ambient such as argon, hydrogen or nitrogen.
Claim 7
Dependent Claim
32 words
A method as in claim 4 wherein x=3.1, the methane molar percentage is about 2, the total sputtering gas pressure is about 10 milliTorr and the radio-frequency power is about 500 watts.
Claim 8
Dependent Claim
29 words
A method as in claim 6 wherein the heating step is carried out at a temperature of approximately 750 degrees Celsius for 30 minutes in 10 -6 Torr vacuum.
Claim 9
Independent Claim
105 words
A method of making a semiconductor device that includes electrical connections to silicon, each connection including a silicide layer on the silicon, a diffusion-barrier layer on the silicide layer and a layer of aluminum on the diffusion-barrier layer, said method comprising the steps of forming a film of Ti x C on the silicon, in a single heating step, converting said film to a TiSi 2 layer on the silicon and a layer of Ti y C on the TiSi 2 layer, where x is both greater than one and greater than y, and forming a layer of aluminum on the Ti y C layer.
Claim 10
Independent Claim
105 words
A method of making a semiconductor device that includes electrical connections to silicon, each connection including a silicide layer on the silicon, a diffusion-barrier layer on the silicide layer and a layer of aluminum on the diffusion-barrier layer, said method comprising the steps of forming a film of Ti x C on the silicon, in a single heating step, converting said film to a TiSi 2 layer on the silicon and a layer of Ti y C on the TiSi 2 layer, where x is both greater than one and greater than y, and forming a layer of aluminum on the Ti y C layer.
Claim 11
Dependent Claim
8 words
A method as in claim 8 wherein 1<x<5.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-03-04 | 1988-09-03 | 1989-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-03-04 | 1992-09-03 | 1993-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-03-04 | 1996-09-03 | 1997-03-05 | $7700.00 | Window Closed / Lapsed |