Patent US1954868A successfully refreshed from Google Patents.
US3889359A
Expired / Lapsed
US
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Ohmic contacts to silicon
Assignee: AT&T Inc
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Filing: 1973-12-10
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Granted: 1975-06-17
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Expires: 1993-12-10
Abstract
Abstract Ohmic contact to relatively high resistivity n-type silicon is made by forming a thin layer of platinum on the silicon surface by means of chemical vapor deposition (CVD) using a phosphorus compound of platinum. The structure then is sintered by heating at about 700* C. for from five to ten minutes thereupon forming a good ohmic contact of the platinum silicide type without the necessity of the separate impurity diffusion treatment usually required to increase the surface impurity concentration.
Inventors
- 👤 Myron Joel Rand
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 03:42
CPC Classifications
H; H10; H10P; H10P95/00; H10P95/50; Y; Y10; Y10S; Y10S148/00; Y10S148/018; Y10S148/02; Y10S148/147
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
144 words
IN THE FABRICATION OF A SILICON SEMICONDUCTOR DEVICE WHICH INCLUDES THE STEP OF INTRODUCING INTO A PORTION OF A PTYPE CONDUCTIVITY SILICON SEMICONDUCTOR BODY AN N-TYPE IMPURITY TO CONVERT THE CONDUCTIVITY TYPE OF SAID PORTION TO AN NTYPE CONDUCTIVITY ZONE, THE FURTHER STEPS OF FORMING A SILICON OXIDE MASK ON THE SURFACE OF SAID PORTION TO DEFINE A CONTACT AREA THERETO AND PROCEDDING DIRECTLY AS A NEXT STEP TO DEPOSIT ON SAID MASKED SURFACE PORTION BY THE PROCESS OF CHEMICAL VAPOR DEPOSITION A THIN LAYER OF PLATINUM, SAID PROCESS COMPRISING EXPOSING SAID MASKED SURFACE PORTION TO A GASEOUS AMBIENT CONTANING A VAPOR OF A PHOSPHOROUS COMPOUND OF PLATINUM WHILE SAID SEMICONDUCTOR BODY IS AT A TEMPERATURE OF BETWEEN 100* AND 500*C., FOLLOWED BY HEATING SAID BODY AT A TEMPERATURE OF FROM ABOUT 675*C. TO 750*C, FOR A PERIOD OF FROM 5 TO 10 MINUTES.
Claim 2
Dependent Claim
144 words
IN THE FABRICATION OF A SILICON SEMICONDUCTOR DEVICE WHICH INCLUDES THE STEP OF INTRODUCING INTO A PORTION OF A PTYPE CONDUCTIVITY SILICON SEMICONDUCTOR BODY AN N-TYPE IMPURITY TO CONVERT THE CONDUCTIVITY TYPE OF SAID PORTION TO AN NTYPE CONDUCTIVITY ZONE, THE FURTHER STEPS OF FORMING A SILICON OXIDE MASK ON THE SURFACE OF SAID PORTION TO DEFINE A CONTACT AREA THERETO AND PROCEDDING DIRECTLY AS A NEXT STEP TO DEPOSIT ON SAID MASKED SURFACE PORTION BY THE PROCESS OF CHEMICAL VAPOR DEPOSITION A THIN LAYER OF PLATINUM, SAID PROCESS COMPRISING EXPOSING SAID MASKED SURFACE PORTION TO A GASEOUS AMBIENT CONTANING A VAPOR OF A PHOSPHOROUS COMPOUND OF PLATINUM WHILE SAID SEMICONDUCTOR BODY IS AT A TEMPERATURE OF BETWEEN 100* AND 500*C., FOLLOWED BY HEATING SAID BODY AT A TEMPERATURE OF FROM ABOUT 675*C. TO 750*C, FOR A PERIOD OF FROM 5 TO 10 MINUTES.
Claim 3
Dependent Claim
22 words
The process in accordance with claim 1 in which the platinum layer has a thickness of from about 500 to 700 angstroms.
Claim 4
Dependent Claim
24 words
The process in accordance with claim 2 in which said portion has a resistivity in the range from about 2 to 10 ohms centimeters.
Claim 5
Dependent Claim
20 words
The process in accordance with claim 1 in which the phosphorous compound of platinum is tetrakis (trifluorophosphine) platinum, Pt (PF3)4.
Claim 6
Dependent Claim
36 words
The process in accordance with claim 4 in which the temperature of the semiconductor body during the chemical vapor deposition step is about 225* C. and the deposition period is for about 5 to 10 minutes.
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) | 1978-06-16 | 1978-12-16 | 1979-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-16 | 1982-12-16 | 1983-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-16 | 1986-12-16 | 1987-06-17 | $7700.00 | Window Closed / Lapsed |