Polycrystalline silicon rod, production method therefor, and FZ silicon single crystal

Patent metadata

Field	Value
Publication number	US-10343922-B2
Application number	US-201515548569-A
Country	US
Kind code	B2
Filing date	Dec 10, 2015
Priority date	Feb 19, 2015
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A plate-shaped sample with a cross-section perpendicular to a radial direction of a polycrystalline silicon rod as a principal surface is sampled from a region from a center (r=0) of the polycrystalline silicon rod to R/3. Then, the sample is disposed at a position at which a Bragg reflection from a (111) Miller index plane is detected. In-plane rotation with a rotational angle φ on the sample is performed with a center of the sample as a rotational center such that an X-ray irradiation region defined by a slit performs φ-scanning on the principal surface of the sample to obtain a diffraction chart indicating dependency of a Bragg reflection intensity from the (111) Miller index plane on a rotational angle of the sample. A ratio (Sp/St) between an area Sp of a peak part appearing in the diffraction chart and a total area St of the diffraction chart is calculated.

First claim

The invention claimed is:

1. A production method for a polycrystalline silicon rod having a radius R of 65 mm or more by a chemical vapor deposition method, the production method comprising
causing the polycrystalline silicon rod to grow under a condition set such that a feed gas amount is reduced by 2% or more in a second region from r=R/3 to r=R/2, and furthermore, the feed gas amount is reduced by 5% or more in a third region from r=R/2 to r=R in a deposition step of the polycrystalline silicon rod, where the feed gas amount at the start of deposition is set to be 100, and r=0 at a center of the polycrystalline silicon rod.

2. A polycrystalline silicon rod produced by the method according to claim 1 , wherein
an area ratio S p /S t of the polycrystalline silicon rod is 2% or less, the area ratio S p /S t being measured by an X-ray diffraction method comprising:
(1a) sampling a plate-shaped sample with a cross-section perpendicular to a radial direction of the polycrystalline silicon rod as a principal surface from a region extending from a center (r=0) of the polycrystalline silicon rod to R/3;
(1b) disposing the plate-shaped sample at a position at which a Bragg reflection from a (111) Miller index plane is detected;
(1c) performing in-plane rotation with a rotational angle ϕ on the plate-shaped sample with a center of the plate-shaped sample as a rotational center such that an X-ray irradiation region defined by a slit performs ϕ-scanning on the principal surface of the plate-shaped sample to obtain a diffraction chart indicating dependency of a Bragg reflection intensity from the (111) Miller index plane on a rotational angle of the plate-shaped sample; and
(1d) calculating a ratio (S p /S t ) between an area S p of a peak part appearing in the diffraction chart and a total area S t of the diffraction chart.

3. The polycrystalline silicon rod according to claim 2 , wherein the peak part is defined to have an S/N ratio of 3 or more.

4. An FZ silicon single crystal obtained by being caused to grow with the polycrystalline silicon rod according to claim 2 as a raw material.

5. A polycrystalline silicon rod produced by the method according to claim 1 , wherein
an average value of area ratios S p /S t of the polycrystalline silicon rod is 0.5% or less, the average value of area ratios S p /S t being measured by an X-ray diffraction method comprising:
(2a) sampling at least one plate-shaped sample with a cross-section perpendicular to a radial direction of the polycrystalline silicon rod as a principal surface from each region of a first region extending from a center (r=0) of the polycrystalline silicon rod to r=R/3, a second region extending from r=R/3 to r=R/2, and a third region extending from r=R/2 to r=R;
(2b) disposing the plate-shaped sample at a position at which a Bragg reflection from a (111) Miller index plane is detected;
(2c) performing in-plane rotation with a rotational angle ϕ on the plate-shaped sample with a center of the plate-shaped sample as a rotational center such that an X-ray irradiation region defined by a slit performs ϕ-scanning on the principal surface of the plate-shaped sample to obtain a diffraction chart indicating dependency of a Bragg reflection intensity from the (111) Miller index plane on a rotational angle of the plate-shaped sample;
(2d) calculating a ratio (S p /S t ) between an area S p of a peak part appearing in the diffraction chart and a total area S t of the diffraction chart; and
(2e) calculating an average value of the area ratios S p /S t for the plurality of plate-shaped samples.

6. The polycrystalline silicon rod according to claim 5 , wherein the peak part is defined to have an S/N ratio of 3 or more.

7. An FZ silicon single crystal obtained by being caused to grow with the polycrystalline silicon rod according to claim 5 as a raw material.

8. The production method for a polycrystalline silicon rod according to claim 7 , wherein the condition is set such that the feed gas amount is reduced by 2% to 5% in the second region from r=R/3 to r=R/2, and furthermore, the feed gas amount is reduced by 5% to 8% in the third region from r=R/2 to r=R.

9. A polycrystalline silicon rod produced by the method according to claim 8 , wherein
an area ratio S p /S t of the polycrystalline silicon rod is 2% or less, the area ratio S p /S t being measured by an X-ray diffraction method being:
(1a) sampling a plate-shaped sample with a cross-section perpendicular to a radial direction of the polycrystalline silicon rod as a principal surface from a region extending from a center (r=0) of the polycrystalline silicon rod to R/3;
(1b) disposing the plate-shaped sample at a position at which a Bragg reflection from a (111) Miller index plane is detected;
(1c) performing in-plane rotation with a rotational angle ϕ on the plate-shaped sample with a center of the plate-shaped sample as a rotational center such that an X-ray irradiation region defined by a slit performs ϕ-scanning on the principal surface of the plate-shaped sample to obtain a diffraction chart indicating dependency of a Bragg reflection intensity from the (111) Miller index plane on a rotational angle of the plate-shaped sample; and
(1d) calculating a ratio (S p /S t ) between an area S p of a peak part appearing in the diffraction chart and a total area S t of the diffraction chart.

10. The polycrystalline silicon rod according to claim 9 , wherein the peak part is defined to have an S/N ratio of 3 or more.

11. An FZ silicon single crystal obtained by being caused to grow with the polycrystalline silicon rod according to claim 9 as a raw material.

12. A polycrystalline silicon rod produced by the method according to claim 8 , wherein
an average value of area ratios S p /S t of the polycrystalline silicon rod is 0.5% or less, the average value of area ratios S p /S t being measured by an X-ray diffraction method comprising:
(2a) sampling at least one plate-shaped sample with a cross-section perpendicular to a radial direction of the polycrystalline silicon rod as a principal surface from each region of a first region extending from a center (r=0) of the polycrystalline silicon rod to r=R/3, a second region extending from r=R/3 to r=R/2, and a third region extending from r=R/2 to r=R;
(2b) disposing the plate-shaped sample at a position at which a Bragg reflection from a (111) Miller index plane is detected;
(2c) performing in-plane rotation with a rotational angle ϕ on the plate-shaped sample with a center of the plate-shaped sample as a rotational center such that an X-ray irradiation region defined by a slit performs ϕ-scanning on the principal surface of the plate-shaped sample to obtain a diffraction chart indicating dependency of a Bragg reflection intensity from the (111) Miller index plane on a rotational angle of the plate-shaped sample;
(2d) calculating a ratio (S p /S t ) between an area S p of a peak part appearing in the diffraction chart and a total area S t of the diffraction chart; and
(2e) calculating an average value of the area ratios S p /S t for the plurality of plate-shaped samples.

13. The polycrystalline silicon rod according to claim 12 , wherein the peak part is defined to have an S/N ratio of 3 or more.

14. An FZ silicon single crystal obtained by being caused to grow with the polycrystalline silicon rod according to claim 12 as a raw material.

Assignees

• Shinetsu Chemical Co

Inventors

• Miyao Shuichi
• Netsu Shigeyoshi

Classifications

• C30B29/06

  Silicon · CPC title

• C01B33/02

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

• C01P2002/78

  by stacking-plane distances or stacking sequences · CPC title

• C01P2002/74

  by peak-intensities or a ratio thereof only · 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