Patent JPS4947742A successfully refreshed from Google Patents.
US4868013A
Expired / Lapsed
US
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Fluidized bed process
Assignee: Albemarle Corp
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Filing: 1988-03-07
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Granted: 1989-09-19
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Expires: 2008-03-07
Abstract
Abstract Undesirable conversion of a silicon source, such as silane, in the freeboard above a fluidized bed of silicon particles in a fluidized bed reactor, can be reduced by cooling the gas within the freeboard. Preferably, the reduction in temperature is achieved by introducing into the freeboard, a stream of relatively cool quench gas such as hydrogen, which also reduces the concentration of silane in the freeboard. As a result of these two factors, the invention improves the service factor of the fluidized bed apparatus, and reduces the amount of silane conversion to undesired by-products.
Inventors
- 👤 Robert H. Allen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 20:00
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/02; C01B33/021; C01B33/027; C01B33/029; B; B01; B01J; B01J8/00; B01J8/18; B01J8/1836; B01J2208/00; B01J2208/00008; B01J2208/00017; B01J2208/00026; B01J2208/00035; B01J2208/00088; B01J2208/00327; B01J2208/00336; B01J2208/00353; B01J2208/00371; B01J2208/00389; B01J2208/00407; Y; Y10; Y10S; Y10S118/00; Y10S118/05
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
162 words
A fluidized bed process for the preparation of polysilicon, said process comprising (i) fluidizing a bed of silicon particles, within a reactor having a bed zone for said particles and a freeboard above said bed zone, with a motive stream of deposition gas comprising a silicon source, said bed zone being at a temperature above the thermal decomposition temperature of said silicon source, whereby a portion of said silicon source is decomposed in said bed zone to deposit silicon metal on said bed of silicon particles, and a remaining portion of said silicon source exits said bed zone and enters said freeboard, and (ii) introducing a flow of quench gas at a temperature below about 200° C. into said freeboard above the upper boundary of said bed zone, said flow of quench gas being sufficient to reduce the temperature and concentration of said silicon source in said freeboard, and thereby reduce the amount of decomposition of said silicon source in said freeboard.
Claim 2
Dependent Claim
162 words
A fluidized bed process for the preparation of polysilicon, said process comprising (i) fluidizing a bed of silicon particles, within a reactor having a bed zone for said particles and a freeboard above said bed zone, with a motive stream of deposition gas comprising a silicon source, said bed zone being at a temperature above the thermal decomposition temperature of said silicon source, whereby a portion of said silicon source is decomposed in said bed zone to deposit silicon metal on said bed of silicon particles, and a remaining portion of said silicon source exits said bed zone and enters said freeboard, and (ii) introducing a flow of quench gas at a temperature below about 200° C. into said freeboard above the upper boundary of said bed zone, said flow of quench gas being sufficient to reduce the temperature and concentration of said silicon source in said freeboard, and thereby reduce the amount of decomposition of said silicon source in said freeboard.
Claim 3
Dependent Claim
11 words
The method of claim 1, wherein said silicon source is silane.
Claim 4
Dependent Claim
20 words
The method of claim 2, wherein the temperature within said bed zone is from about 620° to about 650° C.
Claim 5
Dependent Claim
28 words
The method of claim 3, wherein the flow rate of said motive stream of deposition gas has a U/U min ratio of from about 1.5 to about 3.5.
Claim 6
Dependent Claim
40 words
The method of claim 4, wherein said quench gas is at ambient temperature and the amount of quench gas introduced into said freeboard is sufficient to reduce the temperature of gas within said freeboard to at least about 400° C.
Claim 7
Dependent Claim
24 words
The method of claim 5, wherein said quench gas is selected from the class consisting of hydrogen, helium, argon, and neon, and mixtures thereof.
Claim 8
Dependent Claim
11 words
The method of claim 6, wherein said quench gas is hydrogen.
Claim 9
Dependent Claim
26 words
The method of claim 1, wherein the flow rate of quench gas is within the range of 25-100 percent of the flow rate of deposition gas.
Claim 10
Dependent Claim
19 words
The method of claim 1, wherein the bed particles after silicon deposition have a d ps of 300-2000 microns.
Claim 11
Dependent Claim
20 words
The method of claim 9, wherein said particles have a d ps of from about 600 to about 800 microns.
Claim 12
Dependent Claim
22 words
The method of claim 1, wherein said silicon source is selected from the class consisting of silane, monochlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane.
Claim 13
Dependent Claim
22 words
The method of claim 11, wherein said silicon source is dichlorosilane and the temperture within said bed zone is about 800°-900° C.
Claim 14
Dependent Claim
23 words
The method of claim 11, wherein said silicon source is trichlorosilane and the temperature within said bed zone is from about 1000°-1100° C.
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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) | 1992-09-18 | 1993-03-20 | 1993-09-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-09-18 | 1997-03-20 | 1997-09-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-09-18 | 2001-03-20 | 2001-09-19 | $7700.00 | Window Closed / Lapsed |