Patent US4668330A successfully refreshed from Google Patents.
US4668330A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Furnace contamination
Assignee: SunEdison Inc
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Filing: 1985-12-05
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Granted: 1987-05-26
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Expires: 2005-12-05
Abstract
Abstract The invention described herein describes certain test wafers to be used in diagnosing heavy metal contamination in furnaces used in the manufacture of electronic devices and the method of referencing such wafers to a common wafer source for establishing an accurate baseline for a furnace to determine if it is functioning adequately or if an impurity or contaminant problem exists.
Inventors
- 👤 Paul F. Golden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 14:51
CPC Classifications
H; H10; H10P; H10P72/00; H10P72/04; H10P72/0431; H10P72/0434; Y; Y10; Y10S; Y10S148/00; Y10S148/007; Y10S438/00; Y10S438/974
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
104 words
The method of detecting heavy metal impurities and contamination in furnaces used in the manufacture of electronic devices comprising determining the relative susceptibility of semiconductor test wafers to oxygen induced stacking fault defects to the oxygen induced stacking fault defects of standard or reference wafers to provide a reference ratio, processing said test wafers in the furnace to be used to manufacture electronic devices and determine the amount of oxygen induced stacking faults under the furnace operating conditions and multiplying such determined defects by the reference ratio supplied with the test wafers to determine if a base level of heavy metal contamination is present.
Claim 2
Independent Claim
104 words
The method of detecting heavy metal impurities and contamination in furnaces used in the manufacture of electronic devices comprising determining the relative susceptibility of semiconductor test wafers to oxygen induced stacking fault defects to the oxygen induced stacking fault defects of standard or reference wafers to provide a reference ratio, processing said test wafers in the furnace to be used to manufacture electronic devices and determine the amount of oxygen induced stacking faults under the furnace operating conditions and multiplying such determined defects by the reference ratio supplied with the test wafers to determine if a base level of heavy metal contamination is present.
Claim 3
Dependent Claim
44 words
The method of claim 1 wherein when the oxygen induced stacking fault defects, calculated from the test wafers processed in the furnace using the reference ratio, deviate 50% from the base level for the furnace the heavy metal impurity or contamination condition has changed.
Claim 4
Dependent Claim
12 words
The method of claim 1 wherein the test wafers are silicon wafers.
Claim 5
Dependent Claim
17 words
The method of claim of claim 1 wherein the test wafers are silicon N type (100) wafers.
References Cited (Backward Citations)
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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) | 1990-05-25 | 1990-11-24 | 1991-05-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-25 | 1994-11-24 | 1995-05-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-25 | 1998-11-24 | 1999-05-26 | $7700.00 | Window Closed / Lapsed |