Polycrystalline silicon rod, method for producing polycrystalline silicon rod, and single-crystalline silicon

Patent metadata

Field	Value
Publication number	US-10865498-B2
Application number	US-201816157858-A
Country	US
Kind code	B2
Filing date	Oct 11, 2018
Priority date	May 7, 2014
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

Abstract

In the present invention, once a polycrystalline silicon rod is grown by the Siemens process, the polycrystalline silicon rod is heat-treated within a temperature range from 750° C. to 900° C. to relieve residual stress in the crystal. According to the experiment of the present inventors, residual stress can be relieved satisfactorily by heat treatment at the above-described low temperature, and in addition, metal contamination cannot be induced and the physical properties of the polycrystalline silicon rod cannot be changed. The above heat treatment can be conducted inside a furnace used to grow the polycrystalline silicon rod, and can also be conducted outside a furnace used to grow the polycrystalline silicon rod. According to the present invention, a polycrystalline silicon rod with residual stress (σ) of not more than +20 MPa evaluated by a 2θ-sin2Ψ diagram can be obtained.

First claim

The invention claimed is:

1. A method of producing a polycrystalline silicon rod, comprising:
(i) growing a polycrystalline silicon rod by a Siemens process, and
(ii) after said growing, heat-treating the polycrystalline silicon rod, which was grown, at a temperature ranging from 750° C. to 900° C. for stress relief,
wherein said heat-treating is conducted inside a furnace in which the polycrystalline silicon rod was grown and
wherein said heat-treating occurs in absence of growing the polycrystalline silicon rod.

Assignees

• Shinetsu Chemical Co

Inventors

• Miyao Shuichi
• Netsu Shigeyoshi
• Okada Tetsuro

Classifications

• C30B29/06

  Silicon · CPC title

• C01P2002/70

  defined by measured X-ray, neutron or electron diffraction data · CPC title

• 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

• C30B13/08 Primary

  adding crystallising materials or reactants forming it in situ to the molten zone · CPC title

• C30B15/02

  adding crystallising materials or reactants forming it in situ to the melt · CPC title