Patent US4556784A successfully refreshed from Google Patents.
US4556784A
Expired / Lapsed
US
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Method for controlling vertically arranged heaters in a crystal pulling device
Assignee: Sumitomo Electric Industries Ltd
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Filing: 1983-10-07
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Granted: 1985-12-03
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Expires: 2003-10-07
Abstract
Abstract In the pulling of a single crystal from a melt by the Czochralski method the temperature of the melt and the crystal is controlled by a plurality of heaters surrounding the crucible in vertically disposed relation relative to each other. The lowermost heater is controlled by an automatic temperature controller in response to the temperature of the bottom of the crucible and the remaining heaters are controlled by the selectring a specific ratio for the power supply of each of the remaining heaters with respect to the power supply of the lowermost heater.
Inventors
- 👤 Ryusuke Nakai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:35
CPC Classifications
C; C30; C30B; C30B15/00; C30B15/14; C30B15/20
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
76 words
In a method for pulling a single crystal from a melt in a crucible surrounded by a plurality of vertically disposed electrical heaters connected to respective sources of controlled electrical power comprising controlling one of said heaters by means of an automatic temperature controller and controlling the remaining heaters by maintaining a predetermined power ratio of the controlled power for the remaining heaters with respect to the controlled power for said one of said one heaters.
Claim 2
Dependent Claim
76 words
In a method for pulling a single crystal from a melt in a crucible surrounded by a plurality of vertically disposed electrical heaters connected to respective sources of controlled electrical power comprising controlling one of said heaters by means of an automatic temperature controller and controlling the remaining heaters by maintaining a predetermined power ratio of the controlled power for the remaining heaters with respect to the controlled power for said one of said one heaters.
Claim 3
Dependent Claim
25 words
A method as set forth claim 1 further comprising operating said automatic temperature controller in response to the temperature of the bottom of said crucible.
Claim 4
Dependent Claim
38 words
A method as set forth in claim 1 wherein the lowermost heater adjacent the bottom of the crucible for controlling the single crystal diameter and wherein the temperature gradient in the crucible corresponds to said power supply ratio.
References Cited (Backward Citations)
US3086385A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-12-02 | 1989-06-03 | 1989-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-12-02 | 1993-06-03 | 1993-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-12-02 | 1997-06-03 | 1997-12-03 | $7700.00 | Window Closed / Lapsed |