Patent US4231809A successfully refreshed from Google Patents.
US4231809A
Expired / Lapsed
US
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Method of removing impurity metals from semiconductor devices
Assignee: AT&T Inc
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Filing: 1979-05-25
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Granted: 1980-11-04
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Expires: 1999-05-25
Abstract
Abstract A process is disclosed for gettering deleterious metal impurities, particularly the transition metals such as Cu, Fe, Co, Ni and Cr from silicon wafers by high temperature treatment for a comparatively short time in a hydrogen chloride vapor at low oxygen pressure. The low oxygen pressure inhibits the oxide growth on the silicon surfaces to thicknesses of not more than about 150 Angstroms, sufficient to protect the silicon surface but not so thick as to constitute a barrier to outdiffusion of the gettered impurities. This particular process may be preceded and followed by other previously known gettering techniques.
Inventors
- 👤 Paul F. Schmidt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:44
CPC Classifications
H; H10; H10P; H10P36/00; H10P36/03; Y; Y10; Y10S; Y10S148/00; Y10S148/003; Y10S148/024
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
69 words
In a process for gettering transition metal impurities from a body of silicon semiconductor material which comprises heating the body in an ambient which includes hydrogen chloride and oxygen the improvement comprising the ambient contains oxygen in a percentage by volume of from about 0.5 and 1.0 to grow a silicon oxide film on the surface of said body to a thickness of not more than about 150 Angstroms.
Claim 2
Dependent Claim
69 words
In a process for gettering transition metal impurities from a body of silicon semiconductor material which comprises heating the body in an ambient which includes hydrogen chloride and oxygen the improvement comprising the ambient contains oxygen in a percentage by volume of from about 0.5 and 1.0 to grow a silicon oxide film on the surface of said body to a thickness of not more than about 150 Angstroms.
Claim 3
Dependent Claim
22 words
The process in accordance with claim 1 in which the hydrogen chloride is present in a percentage by volume of about 0.5.
Claim 4
Dependent Claim
24 words
The process in accordance with claim 2 in which the body is heated in the range from 900 degrees C. to 1300 degrees C.
Claim 5
Dependent Claim
35 words
The process in accordance with claim 3 in which said body is placed in a furnace at 900 degrees C. and then ramped up to 1250 degrees C. in a period of about 20 minutes.
Claim 6
Dependent Claim
25 words
The process in accordance with claim 3 in which said body is heated at a temperature of about 1250 degrees C. for about 10 minutes.
Claim 7
Dependent Claim
54 words
In a process for gettering transition metal impurities from a body of silicon semiconductor material which comprises heating the body in an ambient which includes hydrogen chloride and dry oxygen the improvement comprising the ambient comprises by volume, hydrogen chloride about 0.5 percent, oxygen from about 0.5 to 1.0 percent, and the balance argon.
Claim 8
Dependent Claim
54 words
In a process for gettering transition metal impurities from a body of silicon semiconductor material which comprises heating the body in an ambient which includes hydrogen chloride and dry oxygen the improvement comprising the ambient comprises by volume, hydrogen chloride about 0.5 percent, oxygen from about 0.5 to 1.0 percent, and the balance argon.
Claim 9
Dependent Claim
36 words
The method in accordance with claim 6 in which the body is placed in a furnace at about 900 degrees C. and ramped up to a temperature of about 1250 degrees C. in about 20 minutes.
Claim 10
Dependent Claim
25 words
The process in accordance with claim 6 in which said body is heated at a temperature of about 1250 degrees C. for about ten minutes.
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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) | 1983-11-04 | 1984-05-05 | 1984-11-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-11-04 | 1988-05-05 | 1988-11-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-11-04 | 1992-05-05 | 1992-11-04 | $7700.00 | Window Closed / Lapsed |