US3617348A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for the evaporation of chromium-silver
Assignee: Motorola Solutions Inc
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Filing: 1969-10-15
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Granted: 1971-11-02
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Expires: 1989-10-15
Abstract
Abstract Disclosed is a method and apparatus for the vacuum evaporation of chromium-silver metallization on a silicon substrate by which the chromium adherence is improved and by which very large quantities of silver may be deposited in a short time. The evaporative system described will form a chromium-silver multilayer which adheres tightly to a substrate such as silicon. This system is feasible for the fast large-scale production formation of chromium-silver layers on silicon. The fast evaporative rate of the silver is accomplished by the use of a silver wettable insert in a silver nonwettable crucible.
Inventors
- 👤 Dale T Kelley
- 👤 Billy E Smith
- 👤 Richard W Wilson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 23:24
CPC Classifications
C; C23; C23C; C23C14/00; C23C14/22; C23C14/24; C23C14/243; C23C14/06; C23C14/14; C23C14/16; Y; Y10; Y10S; Y10S438/00; Y10S438/903
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
188 words
A method for the vacuum evaporation of a chromium-silver metallization system on a substrate comprising the steps of evacuating a closed system to a reduced pressure, passing liquid nitrogen through coils in said closed system to further reduce the pressure and remove contaminants therefrom, heating the substrate to a temperature sufficient to remove impurities from the surface thereof, melting silver at a temperature sufficient to remove the impurities therefrom, heating the chromium to a temperature sufficient to remove the impurities thereof, evaporating chromium to form a layer of chromium on said substrate whereby said chromium layer has a resistance of about 12 plus or minus 2 ohms per square, evaporating silver and chromium simultaneously for a period to form an intermediate silver-chromium layer on said chromium layer, evaporating silver from a crucible made from a nonwetting material and containing an insert on the bottom thereof made of a metal taken from the group consisting of tantalum and molybdenum to form a layer of silver on top of said chromium layer, removing the liquid nitrogen from said coil, and passing gas through said coil to warm said closed system.
Claim 2
Dependent Claim
26 words
A method as described in claim 2 whereby said silver evaporation step is continued until a layer of about 1.5 to 2.5 microns thick is obtained.
Claim 3
Independent Claim
52 words
An apparatus adapted for the vacuum evaporation of a chromium-silver metallization system on a substrate comprising a crucible for the silver to be evaporated, said crucible made of a material which is not wetted by silver, and an insert positioned in said crucible made of a material which is wetted by silver.
Claim 4
Dependent Claim
14 words
An apparatus as described in claim 4 wherein said insert is made of tantalum.
Claim 5
Dependent Claim
14 words
An apparatus as described in claim 4 wherein said insert is made of molybdenum.
Claim 6
Dependent Claim
14 words
An apparatus as described in claim 4 wherein said crucible is made of carbon.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-01 | 1975-05-03 | 1975-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-01 | 1979-05-03 | 1979-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-01 | 1983-05-03 | 1983-11-02 | $7700.00 | Window Closed / Lapsed |