US5045502A
Expired / Lapsed
US
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PdIn ohmic contact to GaAs
Assignee: CALIFORNIA 300 LAKESIDE DR 22ND FLR OAKLAND CA 94612-3550 A CORP OF, University of, Regents of
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Filing: 1990-05-10
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Granted: 1991-09-03
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Expires: 2010-05-10
Abstract
Abstract An ohmic contact to a semiconductor such as GaAs and its method of making in which a thin layer of Pd is overlaid preferably with a layer of Group-IV element such as Ge followed by another layer of Pd. This structure is then overlaid with a layer of Pd and In. The atomic ratio of the Pd and In in the entire structure lies between 0.9 and 1.5. This structure is then annealed at a temperature between 350 DEG C. and 675 DEG C. There results a very thin crystalline layer of Ge-doped InGaAs adjacent the GaAs and an overlying PdIn alloy layer providing a contact resistance in the range of 0.1-1 OMEGA -mm.
Inventors
- 👤 Silvanius S. Lau
- 👤 Timothy D. Sands
- 👤 Long-Ching Wang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 23:22
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/01; H10D64/011; H10D64/0116; H10D62/00; H10D62/80; H10D62/85; H10D64/60; H10D64/62; H10W; H10W72/00; H10W72/50; H10W72/551; H10W72/552; H10W72/5522; H10W72/59; H10W72/90; H10W72/951; H10W72/952
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
94 words
A method of forming an ohmic contact, comprising the steps of: a first step of depositing a lower layer comprising palladium on a surface of an n-type semiconductor comprising gallium and arsenic; a second step of depositing an upper layer comprising palladium and indium on said lower layer, wherein a ratio of a total atomic amount of palladium to a total atomic amount of indium contained in a combination of said upper and lower layers lies in a range of 0.9 to 1.5; and annealing said lower and upper layers at an annealing temperature.
Claim 2
Independent Claim
94 words
A method of forming an ohmic contact, comprising the steps of: a first step of depositing a lower layer comprising palladium on a surface of an n-type semiconductor comprising gallium and arsenic; a second step of depositing an upper layer comprising palladium and indium on said lower layer, wherein a ratio of a total atomic amount of palladium to a total atomic amount of indium contained in a combination of said upper and lower layers lies in a range of 0.9 to 1.5; and annealing said lower and upper layers at an annealing temperature.
Claim 3
Dependent Claim
18 words
A method as recited in claim 1, wherein said annealing temperature is no higher than approximately 700° C.
Claim 4
Dependent Claim
55 words
A method as recited in claim 1, wherein said first step comprises: depositing a first layer comprising palladium on said surface; depositing a second layer comprising a group-IV element on said first layer, said group-IV element chosen from the group consisting of germanium, silicon and tin; said lower layer comprising said first and second layers.
Claim 5
Dependent Claim
18 words
A method as recited in claim 3, wherein said second layer is less than 10 nm in thickness.
Claim 6
Dependent Claim
22 words
A method as recited in claim 4, wherein said first layer has a thickness in a range of 5 to 50 nm.
Claim 7
Dependent Claim
31 words
A method as recited in claim 1, wherein said lower layer deposited by said first step further comprises a group-IV element chosen from the group consisting of germanium, silicon and tin.
Claim 8
Dependent Claim
13 words
A method as recited in claim 5, wherein said group-IV element comprises germanium.
Claim 9
Dependent Claim
18 words
A method as recited in claim 5, wherein said annealing temperature lies between 350° C. and 675° C.
Claim 10
Independent Claim
80 words
A method of forming an ohmic contact, comprising the steps of: depositing on an n-type semiconductor comprising gallium and arsenic a first layer comprising palladium and a group-IV element chosen from the group consisting of silicon, germanium and tin, at least a portion of said palladium being deposited at least as close to said semiconductor as all of said group-IV element; depositing on said first layer a second layer comprising palladium and indium; and annealing at least said second layer.
Claim 11
Independent Claim
80 words
A method of forming an ohmic contact, comprising the steps of: depositing on an n-type semiconductor comprising gallium and arsenic a first layer comprising palladium and a group-IV element chosen from the group consisting of silicon, germanium and tin, at least a portion of said palladium being deposited at least as close to said semiconductor as all of said group-IV element; depositing on said first layer a second layer comprising palladium and indium; and annealing at least said second layer.
Claim 12
Dependent Claim
42 words
A method as recited in claim 9, wherein a ratio of a total atomic amount of palladium to a total atomic amount of indium contained in a combination of said first and second layers lies in a range between 0.9 and 1.5.
Claim 13
Dependent Claim
51 words
A method as recited in claim 9, wherein said step of depositing said first layer comprises depositing a third layer no thicker than 50 nm and comprising palladium on said semiconductor and depositing a fourth layer of thickness less than 10 nm and comprising said group-IV element on said third layer.
Claim 14
Dependent Claim
13 words
A method as recited in claim 9, wherein said group-IV element comprises Ge.
Claim 15
Dependent Claim
16 words
A method as recited in claim 12, wherein said semiconductor comprises GaAs as a principal component.
Claim 16
Dependent Claim
42 words
A method as recited in claim 11, wherein a ratio of a total atomic amount of palladium to a total atomic amount of indium contained in a combination of said first and second layers lies in a range between 0.9 and 1.5.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1994-09-02 | 1995-03-04 | 1995-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-02 | 1999-03-04 | 1999-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-02 | 2003-03-04 | 2003-09-03 | $7700.00 | Window Closed / Lapsed |