Core wire holder and method for producing silicon

• US 10,640,385 B2
• Filed: 10/30/2015
• Issued: 05/05/2020
• Est. Priority Date: 11/04/2014
• Status: Active Grant

• Current Assignee: Tokuyama Corporation
• Original Assignee: Tokuyama Corporation
• Inventors: Ishida, Haruyuki
• Primary Examiner(s): Carter, Monica S
• Assistant Examiner(s): Nejad, Mahdi H
• Application Number:
  US15/523,919
• Publication Number:
  US 20170341944A1
• Time in Patent Office: 1,649 Days
• CPC Class Codes: C01B 33/035 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 Class Codes: C23C 16/24 Deposition of silicon only
• CPC Class Codes: C23C 16/4418 Methods for making free-standing articles C23C16/01 takes precedence

Abstract

A core wire holder 3 attached on an electrode 2 placed on a bottom panel of a device 20 for producing silicon by Siemens process includes a silicon core wire holding portion 9 being generally circular truncated cone-shaped, and holding and energizing a silicon core wire 4. The silicon core wire holding portion 9 includes a generally circular truncated cone having an upper surface formed with a silicon core wire insertion hole 7 for holding the silicon core wire 4, and the silicon core wire holding portion 9 includes an upper surface and a side surface, which form a ridge having a curved surface and serving as a chamfered portion 8.

Claims

1. A core wire holder attached on a metal electrode placed on a bottom panel of a device for producing silicon by Siemens process, the core wire holder comprising:

a silicon core wire holding portion being generally circular truncated cone-shaped, and configured to hold and energize a silicon core wire, wherein;

the silicon core wire holding portion is inscribed and includes a generally circular truncated cone having an upper surface formed with a silicon core wire insertion hole for holding the silicon core wire,

the circular truncated cone includes an upper surface in a shape of a first circle with a diameter “

a”

,

the circular truncated cone includes a bottom surface in a shape of a second circle with a diameter “

b”

,

the circular truncated cone has a height “

h”

,

the silicon core wire holding portion includes a chamfered portion having a curved surface formed on a ridge formed by the upper surface and a side surface of the silicon core wire holding portion,

the curved surface has a radius “

R”

of curvature, and

“

a”

, “

b”

, “

h”

, and “

R”

satisfy the following conditions;

a<

b, a≤

h≤

(15*a), and (a/10)≤

R≤

(2*b) such that a possibility in growth of cracking of a silicon rod formed by depositing polysilicon on the silicon core wire is reduced.

2. The core wire holder of claim 1, further comprising:

a cylindrical-shaped or circular truncated cone-shaped base portion.

3. The core wire holder of claim 1, wherein the core wire holder is made of carbon.

4. The core wire holder of claim 1, wherein a material for the core wire holder has a coefficient of thermal expansion at a ratio of 0.7-1.7, and wherein a coefficient of thermal expansion of the silicon rod is 1.

5. A method for producing polysilicon by Siemens process, comprising:

using the core wire holder of claim 1, and

depositing the polysilicon on the silicon core wire.

6. A method for producing polysilicon by Siemens process, comprising:

using the core wire holder of claim 2, and

depositing the polysilicon on the silicon core wire.

7. A method for producing polysilicon by Siemens process, comprising:

using the core wire holder of claim 3, and

depositing the polysilicon on the silicon core wire.

8. A method for producing polysilicon by Siemens process, comprising:

using the core wire holder of claim 4, and

depositing the polysilicon on the silicon core wire.