Patent US3798007A successfully refreshed from Google Patents.
US3798007A
Expired / Lapsed
US
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Method and apparatus for producing large diameter monocrystals
Assignee: International Business Machines Corp
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Filing: 1969-12-05
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Granted: 1974-03-19
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Expires: 1989-12-05
Abstract
Abstract An improved method and apparatus for producing large diameter semiconductor crystals by the Czochralski process wherein a relatively flat temperature profile is maintained within the melt by adding heat to the sides and top of the melt while simultaneously removing heat from the melt through the crystal being pulled and the lower portion of the melt. In the apparatus, the temperature profile is maintained with a deflector to direct heat energy to the top surface of the melt about the crystal being pulled, a heat exchange element to facilitate removal of heat through the crystal being pulled, and means to remove heat through the lower portion of the crucible containing the melt.
Inventors
- 👤 R Bochman
- 👤 R Dessauer
- 👤 D Jen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 16:45
CPC Classifications
C; C30; C30B; C30B15/00; C30B15/20; C30B15/22; C30B15/14; Y; Y10; Y10S; Y10S117/00; Y10S117/90; Y10T; Y10T117/00; Y10T117/10; Y10T117/1024; Y10T117/1032; Y10T117/1068
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
20 words
The method of claim 1 wherein heat is removed from the bottom of the melt through a heat exchange means.
Claim 2
Dependent Claim
40 words
The method of claim 1 wherein a proportionately larger amount of heat is directed to the top of the melt by providing a more efficient insulation about the heating element in the region of the top surface of the melt.
Claim 3
Dependent Claim
18 words
The method of claim 3 wherein relative rotation is provided between the melt and the crystal being grown.
Claim 4
Dependent Claim
19 words
The method of claim 3 wherein heat is removed from the center portion of the melt through the crystal.
Claim 5
Dependent Claim
21 words
The method of claim 5 wherein a heat exchange means is provided to conduct heat away from the crystal being grown.
Claim 6
Dependent Claim
30 words
The method of claim 5 wherein a lower hot zone over the melt, and an upper overlying cooler zone is maintained, and the crystal is withdrawn upwardly through said zones.
Claim 7
Dependent Claim
37 words
The method of claim 7 wherein said hot zone is formed at least in part by directing heat from a heating element inwardly and downwardly toward the melt, and shielding the cooler zone from the heating element.
Claim 8
Dependent Claim
28 words
The method of claim 8 wherein the heater temperature is gradually increased as the length of the crystal increases to compensate for increasing heat transfer through the crystal.
Claim 9
Dependent Claim
158 words
In an apparatus for producing a large diameter substantially defect-free single semiconductor crystal by the Czochralski process having a container for the melt, a hEater disposed about the side of said container, and a mechanism for supporting and lifting the crystal formed in the melt, the improvement comprising; a means to direct a greater porportion of heat energy to the top region of the melt than to the bottom, including an annular shield positioned above the heater to direct radiant heat energy from said heater downwardly and inwardly toward the top surface of the melt, and preventing at least in part radiant heat energy from impinging on the upper portion of the crystal, a heat exchange means to remove heat from the lower portion of the melt, said annular shield and heat exchange means adapted to establish and maintain a relatively flat temperature profile in the melt in the region slightly below the top surface of the melt.
Claim 10
Dependent Claim
31 words
The apparatus of claim 10 wherein said means to remove heat from the lower portion of the container includes a support shaft and a heat exchange means to cool said shaft.
Claim 11
Dependent Claim
36 words
The apparatus of claim 10 wherein said means to remove heat from the upper portion of the melt includes a heat exchange means adapted to effectively cool the crystal as it is withdrawn from the melt.
Claim 12
Dependent Claim
23 words
The apparatus of claim 10 wherein said annular shield a ring of anisotropic material which directs heat inwardly and restricts upward heat transfer.
Claim 13
Dependent Claim
14 words
The apparatus of claim 13 wherein said annular shield is formed of pyrolytic graphite.
Claim 14
Dependent Claim
50 words
The apparatus of claim 10 wherein said means to direct heat energy to the top region of the melt includes insulation means surrounding the upper portion of the crucible and shaped to deflect a proportionately greater amount of heat toward the upper portion of the crucible than the bottom portion.
Claim 15
Dependent Claim
44 words
The apparatus of claim 15 wherein said insulation means includes a layer of pyrolytic graphite tape surrounding substantially the entire outside area of the heater, and a layer of insulation covering the upper portion of the heater, in the region of the melt surface.
Claim 16
Dependent Claim
16 words
The apparatus of claim 16 wherein said layer of insulation is a layer of graphite felt.
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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) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |