Method for measuring three-dimensional shape of silica glass crucible, and method for producing monocrystalline silicon

Patent metadata

Field	Value
Publication number	US-9810526-B2
Application number	US-201214365544-A
Country	US
Kind code	B2
Filing date	Oct 31, 2012
Priority date	Dec 27, 2011
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A method for measuring a three-dimensional shape of an inner surface of a vitreous silica crucible which enables the measurement of the three-dimensional shape of the inner surface of the crucible without contaminating the inner surface of the crucible, is provided. According to the present invention, a method for measuring a three-dimensional shape of a vitreous silica crucible, including a fogging step to form a fog onto an inner surface of the vitreous silica crucible, a three-dimensional shape measuring step to measure a three-dimensional shape of the inner surface, by measuring a reflected light from the inner surface irradiated with light, is provided.

First claim

The invention claimed is:

1. A method for measuring a three-dimensional shape of a vitreous silica crucible having a cylindrical sidewall portion having an opening with a rim portion, a mortar-shaped bottom portion, and a corner portion connecting the sidewall portion and the bottom portion, said corner portion having a curvature larger than a curvature of the bottom portion, wherein the crucible comprises a transparent vitreous silica layer at an inner surface side, and a bubble containing layer at an outer surface side, said method comprising the steps of:
forming a fog onto an inner surface of all portions of the vitreous silica crucible constituted by the sidewall portion, the corner portion, and the mortar-shaped bottom portion,
moving an internal ranging section along the inner surface of all the portions of the vitreous silica crucible in a contactless manner;
measuring a distance between the internal ranging section and the inner surface of the transparent vitreous silica layer as a distance from the inner surface, by subjecting the inner surface of the crucible to irradiation with single laser light and then detecting a reflected light from the inner surface, the laser light being emitted from the internal ranging section in an oblique direction with respect to the inner surface, and the measurement being conducted at a plurality of measuring points along a course of a movement of the internal ranging section, wherein the plurality of measuring points include points at the sidewall portion, the corner portion, and the bottom portion;
obtaining a three-dimensional shape of the inner surface of the crucible, by associating three-dimensional coordinates of each of the measuring points with the distance from the inner surface;
measuring a distance between the internal ranging section and an interface between the transparent vitreous silica layer and the bubble containing layer, as a distance from the interface by using the single laser light and detecting light reflected by the interface with the internal ranging section;
obtaining a three-dimensional shape of the interface by associating three-dimensional coordinates of each of the measuring points with the distance from the interface;
wherein the single laser light emitted from the internal ranging section is partially reflected at the inner surface of the transparent vitreous silica layer and partially reflected at the interface so that two peaks corresponding to the reflected lights from the inner surface and the interface are observed when the reflected lights are measured by a laser displacement gauge provided in the internal ranging section, wherein the internal ranging section is moved closer to or away from the inner surface and/or the internal ranging section is tilted to alter the outgoing direction of the laser light so as to search a position and an angle which allows the observation of the two peaks;

moving an external ranging section along an outer surface of all the portions of the vitreous silica crucible in a contactless manner;
measuring a distance between the external ranging section and the outer surface as a distance from the outer surface, by subjecting the outer surface of the crucible to irradiation with laser light and then detecting a reflected light from the outer surface, the laser light being emitted from the external ranging section in an oblique direction with respect to the outer surface, and the measurement being conducted at a plurality of measuring points along a course of a movement of the external ranging section, wherein the plurality of measuring points include points at the sidewall portion, the corner portion, and the bottom portion;
obtaining a three-dimensional shape of the outer surface of the crucible, by associating three-dimensional coordinates of each of the measuring points with the distance from the outer surface; and
evaluating the crucible based on whether the obtained three-dimensional shape of the inner surface and the obtained three-dimensional shape of the outer surface is a shape within a range defined as being between a shape of a crucible having minimum thickness satisfying a predetermined dimension tolerance and a shape of a crucible having maximum thickness satisfying the predetermined dimension tolerance.

2. The method of claim 1 , wherein the fog is formed by cooling the vitreous silica crucible.

3. The method of claim 1 , wherein the fog is formed by increasing an amount of water vapor contained in an atmosphere around the vitreous silica crucible.

4. The method of claim 1 , wherein an angle of incidence of the laser light emitted from the internal ranging section is 30 to 60 degrees with respect to the inner surface.

5. The method of claim 1 , further comprising a step of: outputting coordinate data of the inner surface three-dimensional shape and the interface three-dimensional shape.

6. The method of claim 1 , wherein
the measurement of the inner surface three-dimensional shape is conducted by holding the crucible with a robot arm for conveyance, the robot arm for conveyance conveying the crucible to a measuring area, and
the entire inner surface of the crucible is measured by repeating the steps of conducting a measurement for a particular position of the crucible with respect to a circumferential direction of the crucible by moving a tip of the internal robot arm between a bottom portion and an opening portion of the crucible and rotating the crucible by the robot arm for conveyance in the circumferential direction of the crucible.

7. The method of claim 6 , wherein the crucible is rotated by the robot arm for conveyance by 6.3 degrees or less.

8. The method of claim 6 , wherein
the robot arm for conveyance holds the crucible by a holding section, and
the holding section holds the crucible by pressing arms against a side surface of the crucible from at least four directions, each of the arms being provided with an elastic member at a surface contacting the crucible.

9. A method for manufacturing a monocrystalline silicon, comprising a monocrystalline silicon pulling step to pull a monocrystalline silicon from a silicone melt contained in a vitreous silica crucible,
wherein conditions for pulling the monocrystalline silicon is determined in accordance with a three-dimensional shape of the vitreous silica crucible, the three-dimensional shape being determined by the method of claim 1 .

Assignees

• Sumco Corp

Inventors

• Sudo Toshiaki
• Sato Tadahiro
• Kitahara Ken

Classifications

• C30B15/20

  Controlling or regulating (controlling or regulating in general G05) · CPC title

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• C30B29/06

  Silicon · CPC title

• C30B15/10

  Crucibles or containers for supporting the melt · CPC title

• C03B19/095

  by centrifuging, e.g. arc discharge in rotating mould (crucibles for crystal pulling in general C30B15/10, C30B35/002) · CPC title