US3926747A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Selective electrodeposition of gold on electronic devices
Assignee: AT&T Inc
•
Filing: 1974-02-19
•
Granted: 1975-12-16
•
Expires: 1994-02-19
Abstract
Abstract In metallizing semiconductor devices of the beam-lead type, electrode and connector surfaces are fabricated by depositing a first layer of titanium on the semiconductor surface, followed by depositing a second layer of either platinum or palladium on the titanium. After a photoresist step in which the second layer is patterned to bare portions of the titanium layer, gold is then selectively electrodeposited on the second layer by limiting the maximum potential that may be attained during plating. Masking the titanium layer during gold electrodeposition is thereby avoided.
Inventors
- 👤 Kenneth Russ Newby
- 👤 Earl Dallas Winters
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:34
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/40; H10P14/46; H10P14/47; C; C25; C25D; C25D3/00; C25D3/02; C25D3/48; C25D5/00; C25D5/02; H10W; H10W20/00; H10W20/40; H05; H05K; H05K3/00; H05K3/22; H05K3/24; H05K3/243; Y; Y10; Y10S; Y10S204/00; Y10S204/07
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
83 words
A METHOD OF ELECTRODEPOSITING FROM SOLUTION A GOLD LAYER ONTO A PLATINUM OF PALLADIUM LAYER, WHERE THE PLATINUM OR PALLADIUM LAYER COVERS PORTIONS OF A TITAMIUM LAYER, LEAVING PORTIONS OF THE TITANIUM LAYER EXPOSED TO THE SOLUTION, CHARACTERIZED IN THAT THE TITANIUM LAYER IS BIASED CATHODIC WITH RESPECT TO AN IMMERSED COUNTER ELECTRODE, SUCH THAT THE CATHODE POTENTIAL AT THE TITANIUM LAYER DOES NOT EXCEED A MAXIMUM VALUE DURING ELECTRODEPOSITION, WHEREBY THE GOLD SELECTIVELY DEPOSITS SUBSTANTIALLY ONLY ON THE PLATINUM OR PALLADIIUM LAYER.
Claim 2
Independent Claim
83 words
A METHOD OF ELECTRODEPOSITING FROM SOLUTION A GOLD LAYER ONTO A PLATINUM OF PALLADIUM LAYER, WHERE THE PLATINUM OR PALLADIUM LAYER COVERS PORTIONS OF A TITAMIUM LAYER, LEAVING PORTIONS OF THE TITANIUM LAYER EXPOSED TO THE SOLUTION, CHARACTERIZED IN THAT THE TITANIUM LAYER IS BIASED CATHODIC WITH RESPECT TO AN IMMERSED COUNTER ELECTRODE, SUCH THAT THE CATHODE POTENTIAL AT THE TITANIUM LAYER DOES NOT EXCEED A MAXIMUM VALUE DURING ELECTRODEPOSITION, WHEREBY THE GOLD SELECTIVELY DEPOSITS SUBSTANTIALLY ONLY ON THE PLATINUM OR PALLADIIUM LAYER.
Claim 3
Dependent Claim
16 words
The method of claim 1 in which the gold layer is electrodeposited onto a platinum layer.
Claim 4
Dependent Claim
39 words
The method of claim 2 in which the value of maximum potential at the titanium layer ranges from about -750 millivolts to -950 millivolts (relative to a saturated calomel reference electrode) in the pH range of 7.5 to 10.
Claim 5
Dependent Claim
16 words
The method of claim 1 in which the gold layer is electrodeposited onto a palladium layer.
Claim 6
Dependent Claim
40 words
The method of claim 4 in which the value of the maximum potential at the titanium layer ranges from about -700 millivolts to -950 millivolts (relative to a saturated calomel reference electrode) in the pH range of 7.5 to 10.
Claim 7
Dependent Claim
14 words
The method of claim 1 in which the titanium layer covers a semiconductor body.
Claim 8
Dependent Claim
71 words
The method of claim 6 including the steps of (a) depositing an oxide on a semiconductor surface, (b) forming apertures therethrough to expose a portion of the surface (c) depositing the titanium layer on the surface of the oxide, (d) depositing the platinum of palladium layer onto portions of the titanium layer, leaving portions of the titanium layer exposed, and (e) electrodepositing the gold layer onto the platinum or palladium layer.
Claim 9
Dependent Claim
24 words
The method of claim 7 in which a photoresist layer is formed on the exposed portions of the titanium layer prior to the electrodeposition.
Claim 10
Dependent Claim
45 words
The method of claim 1 in which the value of the cathode potential is maintained by a procedure which includes monitoring the potential at the titanium layer relative to a reference electrode and adjusting the applied current between the titanium layer and the counter electrode.
References Cited (Backward Citations)
US1862231A
Cited
US1750418A
Cited
US2367314A
Cited
US3122817A
Cited
US3287612A
Cited
US3274670A
Cited
US3388048A
Cited
US3514379A
Cited
US3663279A
Cited
US3708403A
Cited
US3809625A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-15 | 1979-06-16 | 1979-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-15 | 1983-06-16 | 1983-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-15 | 1987-06-16 | 1987-12-16 | $7700.00 | Window Closed / Lapsed |