US3848330A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electromigration resistant semiconductor contacts and the method of producing same
Assignee: Motorola Solutions Inc
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Filing: 1973-03-16
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Granted: 1974-11-19
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Expires: 1993-03-16
Abstract
Abstract A technique of reducing the susceptibility of aluminum semiconductor contacts to electromigration. Aluminum contacts containing a small percentage of copper therein are formed on a semiconductor device by evaporation techniques. Subsequently the device is heated to a temperature of greater than 400*C to alloy the copper into the aluminum and quickly cooled to form copper rich precipitates between the grains of aluminum along the grain boundaries and triple points thereof for the purpose of reducing electromigration along grain boundaries.
Inventors
- 👤 E Hall
- 👤 E Philofsky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 12:40
CPC Classifications
C; C23; C23C; C23C14/00; C23C14/58; C23C14/06; C23C14/14; C23C14/18; H; H10; H10P; H10P95/00; Y; Y10; Y10S; Y10S438/00; Y10S438/927
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
105 words
THE METHOD OF PRODUCING A METALLIC CONTACT FOR A SEMICONDUCTOR DEVICE COMPRISING THE STEPS OF: EVAPORATING A LAYER OF CONTACT METAL COMPRISING ALUMINUM AND AT LEAST A 1 PERCENT PORTION OF COPPER ONTO SAID SEMICONDUCTOR DEVICE; HEATING SAID DEVICE TO A TEMPERATURE SUFFICIENTLY HIGH TO CAUSE SAID COPPER TO GO INTO SOLUTION WITH SAID ALUMINUM AND RAPIDLY COOLING SAID DEVICE AT A RATE OF AT LEAST 50*C PER SECOND TO PRECIPITATE COPPER RICH PRECIPITATES OUT OF SOLUTION TO FORM A FINE GRAIN STRUCTURE HAVING ALUMINUM GRAINS AND GRAINS OF COPPER RICH PRECIPITATES INTERSPERSED BETWEEN SAID ALUMINUM GRAINS ALONG THE GRAIN BOUNDARIES AND TRIPLE POINTS THEREOF.
Claim 2
Independent Claim
105 words
THE METHOD OF PRODUCING A METALLIC CONTACT FOR A SEMICONDUCTOR DEVICE COMPRISING THE STEPS OF: EVAPORATING A LAYER OF CONTACT METAL COMPRISING ALUMINUM AND AT LEAST A 1 PERCENT PORTION OF COPPER ONTO SAID SEMICONDUCTOR DEVICE; HEATING SAID DEVICE TO A TEMPERATURE SUFFICIENTLY HIGH TO CAUSE SAID COPPER TO GO INTO SOLUTION WITH SAID ALUMINUM AND RAPIDLY COOLING SAID DEVICE AT A RATE OF AT LEAST 50*C PER SECOND TO PRECIPITATE COPPER RICH PRECIPITATES OUT OF SOLUTION TO FORM A FINE GRAIN STRUCTURE HAVING ALUMINUM GRAINS AND GRAINS OF COPPER RICH PRECIPITATES INTERSPERSED BETWEEN SAID ALUMINUM GRAINS ALONG THE GRAIN BOUNDARIES AND TRIPLE POINTS THEREOF.
Claim 3
Dependent Claim
45 words
The method recited in claim 1 wherein said heating step includes the step of heating said device in a die bonding apparatus and said cooling step includes the steps of removing said device from said die bonding apparatus and cooling said device in ambient air.
Claim 4
Independent Claim
200 words
The method of producing a metallic contact for a semiconductor device comprising the steps of: forming a protective insulating layer on a surface of said device; forming an opening in a predetermined area of said insulating area to expose a portion of the surface of the semiconductor material of said device as a contact area; depositing a layer of contact metal comprising aluminum and at least a 1 percent portion of copper over said insulating layer and onto said contact area; removing said metal except for metal on said contact area and conductor lines and terminals therefrom; heating said semiconductor device to alloy a predetermined amount of semiconductor material and contact metal together in said contact area; further heating said device to a temperature of at least 400* C to cause said copper to go into solution with said aluminum; and rapidly cooling said device at a rate of at least 50* C per second to precipitate copper rich precipitates out of solution to form a fine grain structure having aluminum grains and grains of copper rich precipitates having a diameter no greater than approximately 1,000 Angstroms interspersed between said aluminum grains along the grain boundaries and triple points thereof.
Claim 5
Independent Claim
200 words
The method of producing a metallic contact for a semiconductor device comprising the steps of: forming a protective insulating layer on a surface of said device; forming an opening in a predetermined area of said insulating area to expose a portion of the surface of the semiconductor material of said device as a contact area; depositing a layer of contact metal comprising aluminum and at least a 1 percent portion of copper over said insulating layer and onto said contact area; removing said metal except for metal on said contact area and conductor lines and terminals therefrom; heating said semiconductor device to alloy a predetermined amount of semiconductor material and contact metal together in said contact area; further heating said device to a temperature of at least 400* C to cause said copper to go into solution with said aluminum; and rapidly cooling said device at a rate of at least 50* C per second to precipitate copper rich precipitates out of solution to form a fine grain structure having aluminum grains and grains of copper rich precipitates having a diameter no greater than approximately 1,000 Angstroms interspersed between said aluminum grains along the grain boundaries and triple points thereof.
Claim 6
Dependent Claim
33 words
The method as recited in claim 3 wherein said layer of contact metal is deposited by evaporating an alloy comprising aluminum and a 1 to 10 percent portion of copper onto said device.
Claim 7
Dependent Claim
21 words
The method as recited in claim 4 wherein said layer of contact metal is deposited by simultaneously evaporating aluminum and copper.
Claim 8
Dependent Claim
45 words
The method recited in claim 5 wherein said heating step includes the step of heating said device in a die bonding apparatus and said cooling step includes the steps of removing said device from said die bonding apparatus and cooling said device in ambient air.
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) | 1977-11-18 | 1978-05-20 | 1978-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-18 | 1982-05-20 | 1982-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-18 | 1986-05-20 | 1986-11-19 | $7700.00 | Window Closed / Lapsed |