US 9,809,902 B2
Method for evaluating silica glass crucible, method for producing silicon single crystals
Toshiaki Sudo, Akita (JP); Tadahiro Sato, Akita (JP); Ken Kitahara, Akita (JP); Eriko Kitahara, Akita (KR); and Makiko Kodama, Akita (JP)
Assigned to SUMCO CORPORATION, Tokyo (JP)
Appl. No. 14/365,523
Filed by SUMCO CORPORATION, Minato-ku, Tokyo (JP)
PCT Filed Oct. 31, 2012, PCT No. PCT/JP2012/078260
§ 371(c)(1), (2) Date Jun. 13, 2014,
PCT Pub. No. WO2013/094318, PCT Pub. Date Jun. 27, 2013.
Claims priority of application No. 2011-282404 (JP), filed on Dec. 22, 2011; application No. 2011-282406 (JP), filed on Dec. 22, 2011; application No. 2011-282408 (JP), filed on Dec. 22, 2011; application No. 2011-282409 (JP), filed on Dec. 22, 2011; application No. 2011-282410 (JP), filed on Dec. 22, 2011; application No. 2011-282411 (JP), filed on Dec. 22, 2011; and application No. 2011-282412 (JP), filed on Dec. 22, 2011.
Prior Publication US 2014/0326172 A1, Nov. 6, 2014
This patent is subject to a terminal disclaimer.
Int. Cl. C30B 15/26 (2006.01); C30B 29/06 (2006.01); G01B 11/00 (2006.01); C30B 15/10 (2006.01); G01B 11/06 (2006.01); G01B 11/245 (2006.01); G01B 11/24 (2006.01); G01J 3/42 (2006.01); G01J 5/58 (2006.01)
CPC C30B 15/26 (2013.01) [C30B 15/10 (2013.01); C30B 29/06 (2013.01); G01B 11/005 (2013.01); G01B 11/06 (2013.01); G01B 11/24 (2013.01); G01B 11/245 (2013.01); G01J 3/42 (2013.01); G01J 5/58 (2013.01)] 21 Claims
OG exemplary drawing
 
1. A method for evaluating 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:
moving an internal ranging section along 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, 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 portions of the vitreous silica crucible constituted by the sidewall portion, the corner portion, and the mortar-shaped bottom portion, 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;
determining a shape of the crucible based on the three-dimensional shape of the inner surface and the three-dimensional shape of the outer surface of the crucible; and
evaluating the crucible based on whether the shape of the crucible determined from the three-dimensional shape of the inner surface and the 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.