Core wire for use in silicon deposition, method for producing said core wire, and method for producing polycrystalline silicon

Patent metadata

Field	Value
Publication number	US-2020002178-A1
Application number	US-201816484065-A
Country	US
Kind code	A1
Filing date	Feb 14, 2018
Priority date	Feb 20, 2017
Publication date	Jan 2, 2020
Grant date	—

Abstract

Efficiency of producing polycrystalline silicon is improved. A silicon filament ( 11 ) is constituted by a rod-shaped member made of polycrystalline silicon. The polycrystalline silicon has an interstitial oxygen concentration of not less than 10 ppma and not more than 40 ppma. On a side surface, in a lengthwise direction, of the rod-shaped member, crystal grains each having a crystal grain size of not less than 1 mm are observed.

First claim

1 . A silicon deposition filament,
the silicon deposition filament being constituted by a rod-shaped member made of polycrystalline silicon, the polycrystalline silicon having an interstitial oxygen concentration of not less than 10 ppma and not more than 40 ppma, on a side surface, in a lengthwise direction, of the rod-shaped member, crystal grains each having a crystal grain size of not less than 1 mm being observed.

2 . The silicon deposition filament as set forth in claim 1 , wherein distribution, in the lengthwise direction of the rod-shaped member, of the interstitial oxygen concentration of the polycrystalline silicon is such that, in a case where the interstitial oxygen concentration at any location in the lengthwise direction is regarded as a reference, the interstitial oxygen concentration varies by not more than ±5 ppma/m with respect to the reference.

3 . The silicon deposition filament as set forth in claim 1 , wherein the silicon deposition filament has a yield stress of not less than 150 MPa per square centimeter at 900° C.

4 . The silicon deposition filament as set forth in claim 1 , wherein a total concentration of phosphorus and boron, which are contained in the polycrystalline silicon, is not more than 1 ppba.

5 . The silicon deposition filament as set forth in claim 1 , wherein:
a cross-sectional area of the silicon deposition filament is not less than 0.1 cm 2 and not more than 6 cm 2 ; and a length of the silicon deposition filament is not less than 0.5 m.

6 . A method for producing a silicon deposition filament, the method comprising the steps of:
producing a polycrystalline silicon ingot, which contains crystal grains each having a crystal grain size of not less than 1 mm and which has an interstitial oxygen concentration of not less than 10 ppma and not more than 40 ppma, by a Czochralski method in which polycrystalline silicon is used as a seed crystal; and processing the polycrystalline silicon ingot into a rod-shaped member.

7 . A method for producing polycrystalline silicon, the method comprising the steps of:
connecting a silicon deposition filament, recited in claim 1 , to at least one pair of electrodes provided on a bottom plate of a chemical reactor for producing polycrystalline silicon; and depositing silicon on a surface of the silicon deposition filament by supplying electric power to the silicon deposition filament so that the silicon deposition filament is heated, while feeding a source gas, containing (i) a gas of a silane compound and (ii) hydrogen, to the chemical reactor.

Assignees

• Tokuyama Corp

Inventors

• Nishikawa Masayoshi
• Inoue Yuji

Classifications

• C01B33/035 Primary

  by decomposition or reduction of gaseous or vaporised silicon compounds in the presence of heated filaments of silicon, carbon or a refractory metal, e.g. tantalum or tungsten, or in the presence of heated silicon rods on which the formed silicon is deposited, a silicon rod being obtained, e.g. Siemens process · CPC title

• C23C16/24

  Deposition of silicon only · CPC title

• C30B29/06

  Silicon · CPC title

• C30B25/005

  Growth of whiskers or needles · CPC title

• C01B33/02

  Silicon (forming single crystals or homogeneous polycrystalline material with defined structure C30B) · CPC title