Patent US4545849A successfully refreshed from Google Patents.
US4545849A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for control of oxygen in silicon crystals
Assignee: Motorola Solutions Inc
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Filing: 1983-03-03
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Granted: 1985-10-08
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Expires: 2003-03-03
Abstract
Abstract An improved process is disclosed for controlling the oxygen content of a Czochralski grown silicon crystal pulled from a silicon melt contained in a silica crucible. High, uniform oxygen concentrations are achieved by attaching an additional piece of silica to the inside of the crucible bottom. Preferably the additional silica is formed from a silica rod bent to a toroid shape. The toroid has about the diameter of the crystal being pulled and is located substantially coaxial with the growing crystal.
Inventors
- 👤 F. Secco d'Aragona
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:58
CPC Classifications
C; C30; C30B; C30B15/00; C30B15/02; C30B15/04
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
87 words
An improved process for pulling a silicon crystal having an elongate axis from a melt contained in a silica crucible to achieve a crystal substantially uniformly doped along said axis with oxygen at a concentration greater than about 1.6×10 18 cm -3 wherein the improvement comprises: attaching to the bottom of the interior of said crucible, substantially coaxial with said axis , a toroidal shaped piece of silica; and rotating said crystal during growth to drive oxygen from said toroidal shaped piece of silica to said crystal.
Claim 2
Dependent Claim
87 words
An improved process for pulling a silicon crystal having an elongate axis from a melt contained in a silica crucible to achieve a crystal substantially uniformly doped along said axis with oxygen at a concentration greater than about 1.6×10 18 cm -3 wherein the improvement comprises: attaching to the bottom of the interior of said crucible, substantially coaxial with said axis , a toroidal shaped piece of silica; and rotating said crystal during growth to drive oxygen from said toroidal shaped piece of silica to said crystal.
Claim 3
Dependent Claim
20 words
The improved process of claim 1 wherein said toroidal shaped piece of silica is formed by bending a silica rod.
Claim 4
Dependent Claim
21 words
The improved process of claim 1 wherein said toroidal shaped piece of silica has substantially the same diameter as said crystal.
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) | 1988-10-07 | 1989-04-08 | 1989-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-07 | 1993-04-08 | 1993-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-07 | 1997-04-08 | 1997-10-08 | $7700.00 | Window Closed / Lapsed |