US4804633A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Silicon-on-insulator substrates annealed in polysilicon tube
Assignee: STMicroelectronics NV
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Filing: 1988-02-18
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Granted: 1989-02-14
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Expires: 2008-02-18
Abstract
Abstract A silicon-on-insulator substrate having a very low threading dislocation density is made by implanting oxygen ions into a silicon substrate while heating the substrate to form a layer of silicon dioxide buried in the silicon substrate and annealing the implanted substrate at high temperature in a novel furnace incorporating a polysilicon tube to constrain the annealing temperature to be uniform over the entire substrate. The silicon-on-insulator substrate is particularly useful for the manufacture of semiconductor devices formed in thin silicon films.
Inventors
- 👤 Thomas W. MacElwee
- 👤 Iain D. Calder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 05:02
CPC Classifications
H; H10; H10P; H10P30/00; H10P30/20; H10P30/208; H10P30/209; H10P72/00; H10P72/04; H10P72/0431; H10P72/0436; H10P95/00; H10P95/90
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
58 words
A method for making a silicon-on-insulator substrate comprising: implanting oxygen ions into a bare silicon substrate while heating the substrate to form a layer of silicon dioxide buried in the silicon substrate; placing the implanted substrate within a polysilicon tube; and maintaining the tube and the substrate at a temperature exceeding 1300 degrees Celsius to anneal the substrate.
Claim 2
Independent Claim
58 words
A method for making a silicon-on-insulator substrate comprising: implanting oxygen ions into a bare silicon substrate while heating the substrate to form a layer of silicon dioxide buried in the silicon substrate; placing the implanted substrate within a polysilicon tube; and maintaining the tube and the substrate at a temperature exceeding 1300 degrees Celsius to anneal the substrate.
Claim 3
Dependent Claim
37 words
A method as defined in claim 1, comprising implanting 1.5×10 18 oxygen ions per square centimeter at an energy of 150 keV and a beam current of 60 mA while maintaining the substrate at 520 degrees Celsius.
Claim 4
Dependent Claim
28 words
A method as defined in claim 2, comprising implanting the oxygen ions in a direction inclined 14 degrees to a direction normal to a surface of the substrate.
Claim 5
Dependent Claim
27 words
A method as defined in claim 1, comprising maintaining the tube and the substrate at 1330 degrees Celsius for at least 6 hours to anneal the substrate.
Claim 6
Dependent Claim
63 words
A method as defined in claim 4, comprising heating the polysilicon tube to 800 degrees Celsius before inserting the implanted substrate therein, increasing the tube temperature to 1330 degrees Celsius, maintaining the tube temperature at 1330 degrees Celsius for at least 6 hours to anneal the substrate, decreasing the tube temperature to 800 degrees Celsius, and removing the annealed substrate from the tube.
Claim 7
Dependent Claim
23 words
A method as defined in claim 5, comprising forming a cap layer of silicon dioxide on the implanted substrate before annealing the substrate.
Claim 8
Dependent Claim
35 words
A method as defined in claim 6, comprising maintaining the tube temperature at 1000 degrees Celsius with an oxygen ambient therein for at least thirty minutes before increasing the tube temperature to 1330 degrees Celsius.
Claim 9
Dependent Claim
31 words
A method as defined in claim 6, comprising densifying the cap layer and forming a thermal oxide at the interface of the cap layer and the substrate before annealing the substrate.
Claim 10
Dependent Claim
20 words
A method as defined in claim 1, comprising monitoring the optical reflectivity of the substrate during annealing of the substrate.
Claim 11
Independent Claim
73 words
A method for making a silicon-on-insulator substrate, comprising implanting oxygen ions into a bare silicon substrate while heating the substrate to form a layer of silicon dioxide buried in the silicon substratae, and annealing the implanted substrate at a temperature exceeding 1300 degrees Celsius while constraining the temperature of the substrate to be uniform during annealing to within one degree Celsius over the entire substrate by heating the substrate within a polysilicon tube.
Claim 12
Independent Claim
73 words
A method for making a silicon-on-insulator substrate, comprising implanting oxygen ions into a bare silicon substrate while heating the substrate to form a layer of silicon dioxide buried in the silicon substratae, and annealing the implanted substrate at a temperature exceeding 1300 degrees Celsius while constraining the temperature of the substrate to be uniform during annealing to within one degree Celsius over the entire substrate by heating the substrate within a polysilicon tube.
References Cited (Backward Citations)
US3867497A
Cited
US4040849A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-02-14 | 1992-08-15 | 1993-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-14 | 1996-08-15 | 1997-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-14 | 2000-08-15 | 2001-02-14 | $7700.00 | Window Closed / Lapsed |