Apparatus of producing silicon single crystal and method of producing silicon single crystal

Patent metadata

Field	Value
Publication number	US-9284660-B2
Application number	US-201113314503-A
Country	US
Kind code	B2
Filing date	Dec 8, 2011
Priority date	Dec 13, 2010
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

An apparatus of producing a silicon single crystal including: an imaging device; a heat shield that has a circular opening; a first operation unit that operates the imaging device and takes a real image of the heat shield and a mirror image of the heat shield reflected on a surface of the silicon melt, measures a spacing between the real image and the mirror image, and calculates a position of a melt-surface; a second operating unit that operates the imaging device and takes an image of a bright-zone in the vicinity of the solid-liquid interface, and calculates a position of the melt-surface based on the image of the bright zone; and a controlling unit that refers a data of the position of the silicon melt obtained by the first operation unit and the second operation unit, and controls the position of the silicon melt.

First claim

What is claimed is:

1. An apparatus of producing a silicon single crystal by pulling a silicon single crystal from a silicon melt formed in a crucible, comprising:
an imaging device that takes an image of a region including a surface of the silicon melt from a direction that is inclined with a predetermined angle about a pulling axis of the silicon single crystal;
a heat shield that is disposed so as to cover a partial surface of the silicon melt and that has a circular opening through which the silicon single crystal during pulling penetrates;
a first operator that operates the imaging device and takes a real image of the heat shield including the opening and a mirror image of the heat shield reflected on the surface of the silicon melt, measures a spacing between the real image and the mirror image, and calculates a position of the surface of the silicon melt;
a second operator that operates the imaging device and takes an image of a bright-zone appearing in the vicinity of an interface between the silicon melt and the silicon single crystal, and calculates a position of the surface of the silicon melt based on a center position of the silicon single crystal that is determined based on the image of the bright zone; and
a controller that refers a data of the position of the surface of the silicon melt obtained by the first operator and a data of the position of the surface of the silicon melt obtained by the second operator, and controls the position of the surface of the silicon melt in during the pulling of the silicon single crystal, wherein
the first operator transforms contours of the real image and the mirror image of the heat shield obtained by the imaging device to project the contours of the real image and the mirror image to a plane corresponding to a lower end position of the heat shield,
the first operator calculates a center position of the projected real image of the heat shield through circular approximation of the contour of the opening of the real image of the heat shield that appears as an elliptic shape,
the first operator calculates a center position of the projected mirror image of the heat shield through circular approximation of the contour of the opening of the mirror image of the heat shield, and
the first operator measures the spacing between the real image and the mirror image based on a spacing between the center positions of the projected real image and the projected mirror image of the heat shield.

2. The apparatus of producing a silicon single crystal according to claim 1 , wherein the first operator determines the contours of the real image and the mirror image of the heat shield based on differential data of the real image and the mirror image taken by the imaging device.

3. The apparatus of producing a silicon single crystal according to claim 1 ,
wherein the first operator selects a contour from contours of each of the real image and the mirror image obtained by the imaging device such that the selected contour encloses an area of not smaller than a predetermined area and the first operator uses the selected contour in calculation of the center position of each of the real image and the mirror image of the heat shield.

4. The apparatus of producing a silicon single crystal according to claim 1 , wherein the imaging device takes an image from an angle such that a deviation between the contour of each of the real image and the mirror image of the heat shield and a circular approximated image of the opening of the heat shield is minimized.

5. The apparatus of producing a silicon single crystal according to claim 1 , wherein in an initial stage of pulling a silicon single crystal, the first operator performs setting of the position of the surface of the silicon melt based on the spacing between the real image and the mirror image of the heat shield;
from the end on the initial stage to a stage where a diameter of the silicon single crystal reaches a predetermined value, the first operator controls the position of the surface of the silicon melt through the controller based on the spacing between the real image and the mirror image of the heat shield; and
in a stage after the diameter of the silicon single crystal reaches the predetermined value, the second operator controls the position of the surface of the silicon melt through the controller based on the center position of the silicon single crystal determined from the image of the bright zone.

6. The apparatus of producing a silicon single crystal according to claim 1 , wherein, at the timing when the diameter of the silicon single crystal reaches a predetermined value, difference between the position of the surface of the silicon melt determined by the first operator and the position of the surface of the silicon melt determined by the second operator is calibrated.

Assignees

• Takanashi Keiichi
• Hamada Ken
• Sumco Corp

Inventors

• Takanashi Keiichi
• Hamada Ken

Classifications

• C30B29/06 Primary

  Silicon · CPC title

• C30B15/26 Primary

  using television detectors; using photo or X-ray detectors · CPC title

• Y10T117/1008

  with responsive control means · CPC title