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EP0450393A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Improved polysilicon and process therefor

Assignee: Ethyl Corp
•
Filing: 1991-03-19
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Granted: —
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Expires: 2011-03-19
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Abstract

Abstract Semiconductor grade polysilicon in the form of free flowing, approximately spherical particles produced in a fluidized bed, and having a reduced surface silicon dust content and hydrogen content. Such products are formed in two operations utilizing fluidized beds. In the first operation, silicon is deposited on polysilicon seed particles. In the second operation, trichlorosilane or other halogenated silane is decomposed at an elevated temperature to provide a thin silicon coat, which binds the silicon fines to the larger particles. While the particles are exposed to the decomposition temperature employed, hydrogen diffuses out of the particles resulting in a reduction in hydrogen content and producing a polysilicon particle with a smooth shiny surface.

Inventors

  • 👤 Robert Hall Allen

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-07 15:04
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/02; C01B33/021; C01B33/027; C01B33/029

Claims Analysis

Total Claims: 10
Claim 1
Independent Claim 48 words
Semiconductor grade polysilicon in bead or bead-like particulate form having a hydrogen content of less than 30 ppma and a surface essentially free of silicon dust, said polysilicon having a center portion of high purity silicon and an outer layer of a dense silicon on the center portion.
Claim 2
Dependent Claim 9 words
The polysilicon of Claim 1 having a shiny surface.
Claim 3
Dependent Claim 19 words
The polysilicon of Claim 1 or 2 having a surface silicon dust content of less than 0.005 weight percent.
Claim 4
Dependent Claim 41 words
The polysilicon of any of the preceding claims wherein the outer layer of dense silicon on the center portion is from 0.1 to 5 microns in thickness and the center portion ranges in average size from 80 microns to 2000 microns.
Claim 5
Dependent Claim 18 words
The polysilicon of Claim 4 having a center portion ranging in average size from 600 to 1000 microns.
Claim 6
Dependent Claim 136 words
A fluidized bed process for reducing the surface silicon dust content and hydrogen content of semiconductor grade polysilicon, comprising the steps of (a) fluidizing in a reaction zone, a bed of semiconductor grade, silane derived polysilicon in bead or bead-like particulate form at a temperature of from 1000° to 1200°C, with a carrier gas admixed with from 0.1 to 5.0 mole percent of a silane compound having the formula SiH 4-n X n , wherein n is an integer of 1 to 4, and X is a halogen selected from the group consisting of chlorine, bromine, and iodine, and (b) recovering from the reaction zone a semiconductor grade polysilicon product having a reduced surface silicon dust content and hydrogen content and having an outer layer of dense silicon on a center portion of high purity silicon.
Claim 7
Dependent Claim 13 words
The process of Claim 6 where said polysilicon product has a shiny surface.
Claim 8
Dependent Claim 33 words
The process of Claim 6 or 7 wherein the carrier gas is hydrogen, the silane compound is trichlorosilane, and the outer layer of dense silicon is from 0.1 to 5 microns in thickness.
Claim 9
Dependent Claim 23 words
The process of any of claims 6-8 wherein the polysilicon product has a surface dust content of less than about 0.005 weight percent.
Claim 10
Dependent Claim 22 words
The process of any of claims 6-9 wherein the polysilicon product has a surface dust content of less than 0.005 weight percent.

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