US3900598A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ohmic contacts and method of producing same
Assignee: Motorola Solutions Inc
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Filing: 1973-07-09
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Granted: 1975-08-19
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Expires: 1993-07-09
Abstract
Abstract A technique for reducing the solubility of a semiconductor material into an aluminum layer making ohmic contact thereto. A small percentage of another metal, such as, iron, magnesium, chromium, manganese, nickel, cobalt and titanium is codeposited with the aluminum metallization to prevent excessive dissolution of the semiconductor material into the metallization during heating of the device.
Inventors
- 👤 Edward L Hall
- 👤 Elliott M Philofsky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 07:44
CPC Classifications
H; H10; H10P; H10P95/00; H10P95/50
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
118 words
A METHOD OF MAKING AN OHMIC CONTACT TO A SEMICONDUCTOR DEVICE COMPRISING THE STEPS OF: FORMING A PROTECTIVE INSULATING MATERIAL PATTERN ON THE SURFACE OF SAID DEVICE WITH CONTACT AREAS OF SILICON LEFT EXPOSED, EVAPORATING A LAYER OF CONTACT METAL COMPRISING ALUMINUM WITH A RELATIVELY SMALL PERCENTAGE OF AT LEAST ANOTHER METAL SELECTED FROM THE GROUP CONSISTING OF IRON, MAGNESIUM, CHROMIUM, MANGANESE AND COBALT ON SAID PATTERN AND ONTO SAID CONTACT AREA, AND HEATING SAID DEVICE TO FORM AN OHMIC CONTACT BETWEEN SAID CONTACT METAL AND SAID CONTACT AREAS OF SILICON, WHEREBY THE NATURE OF THE MATERIAL OF THE DEVICE AT SAID CONTACT AREAS REMAINS SUBSTANTIALLY UNAFFECTED DURING THE HEATING FORMING THE OHMIC CONTACT AND DURING SUBSEQUENT HEATING.
Claim 2
Independent Claim
118 words
A METHOD OF MAKING AN OHMIC CONTACT TO A SEMICONDUCTOR DEVICE COMPRISING THE STEPS OF: FORMING A PROTECTIVE INSULATING MATERIAL PATTERN ON THE SURFACE OF SAID DEVICE WITH CONTACT AREAS OF SILICON LEFT EXPOSED, EVAPORATING A LAYER OF CONTACT METAL COMPRISING ALUMINUM WITH A RELATIVELY SMALL PERCENTAGE OF AT LEAST ANOTHER METAL SELECTED FROM THE GROUP CONSISTING OF IRON, MAGNESIUM, CHROMIUM, MANGANESE AND COBALT ON SAID PATTERN AND ONTO SAID CONTACT AREA, AND HEATING SAID DEVICE TO FORM AN OHMIC CONTACT BETWEEN SAID CONTACT METAL AND SAID CONTACT AREAS OF SILICON, WHEREBY THE NATURE OF THE MATERIAL OF THE DEVICE AT SAID CONTACT AREAS REMAINS SUBSTANTIALLY UNAFFECTED DURING THE HEATING FORMING THE OHMIC CONTACT AND DURING SUBSEQUENT HEATING.
Claim 3
Dependent Claim
61 words
A method as recited in claim 1, wherein said layer of contact metal is evaporated onto said device by the further steps of: placing an alloy comprising aluminum and a 0.1 to 1 percent portion of a metal from said group into a vacuum chamber with said device, and heating said alloy to a sufficiently high temperature to vaporize said alloy.
Claim 4
Independent Claim
135 words
A method of making an ohmic contact to 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 layer 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 with a small percentage addition of at least one other metal selected from the group consisting of iron, magnesium, chromium, manganese, and cobalt over said insulating layer and onto said contact area; removing said metal layer except for metal on said contact area and conductor lines and terminals therefrom; and heating said semiconductor device to alloy a predetermined amount of semicondUctor material from said surface into said metal over said contact area.
Claim 5
Independent Claim
135 words
A method of making an ohmic contact to 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 layer 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 with a small percentage addition of at least one other metal selected from the group consisting of iron, magnesium, chromium, manganese, and cobalt over said insulating layer and onto said contact area; removing said metal layer except for metal on said contact area and conductor lines and terminals therefrom; and heating said semiconductor device to alloy a predetermined amount of semicondUctor material from said surface into said metal over said contact area.
Claim 6
Dependent Claim
37 words
A method as recited in claim 3, wherein said layer of contact metal is deposited by evaporating an alloy comprising aluminum and a 0.1 to 1 percent portion of a metal from said group onto said device.
Claim 7
Dependent Claim
25 words
A method as recited in claim 3, wherein said layer of contact metal is deposited by simultaneously evaporating aluminum and a metal from said group.
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) | 1978-08-18 | 1979-02-17 | 1979-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-18 | 1983-02-17 | 1983-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-18 | 1987-02-17 | 1987-08-19 | $7700.00 | Window Closed / Lapsed |