US 12,227,872 B2
Single-crystal pulling apparatus and single-crystal pulling method
Kiyotaka Takano, Annaka (JP); Wataru Yajima, Nishigo-mura (JP); Kosei Sugawara, Nishigo-mura (JP); Hiroyuki Kamada, Nishigo-mura (JP); and Tomohiko Ohta, Shirakawa (JP)
Assigned to SHIN-ETSU HANDOTAI CO., LTD., Tokyo (JP)
Appl. No. 17/605,399
Filed by SHIN-ETSU HANDOTAI CO., LTD., Tokyo (JP)
PCT Filed Mar. 19, 2020, PCT No. PCT/JP2020/012164
§ 371(c)(1), (2) Date May 16, 2022,
PCT Pub. No. WO2020/225985, PCT Pub. Date Nov. 12, 2020.
Claims priority of application No. 2019-088473 (JP), filed on May 8, 2019.
Prior Publication US 2023/0175166 A1, Jun. 8, 2023
Int. Cl. C30B 15/20 (2006.01); C30B 29/06 (2006.01); C30B 30/04 (2006.01)
CPC C30B 15/20 (2013.01) [C30B 29/06 (2013.01); C30B 30/04 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A single-crystal pulling apparatus comprising:
a pulling furnace which has a heater and a crucible containing a molten single crystal material arranged therein, and which has a central axis; and
a magnetic field generation device which is arranged around the pulling furnace and has superconducting coils and a cryostat incorporating the superconducting coils,
the single-crystal pulling apparatus applying a horizontal magnetic field to the molten single crystal material by energization to the superconducting coils to suppress convection of the molten single crystal material in the crucible,
wherein the magnetic field generation device has four of the superconducting coils, all coil axes of the four superconducting coils being arranged so as to be included in a single horizontal plane,
when a direction of lines of magnetic force at the central axis in the horizontal plane is determined as an X axis, two of the superconducting coils are arranged in each of a first region and a second region divided by a cross section that includes the X axis and the central axis of the pulling furnace,
the four superconducting coils are arranged to have line symmetry about the cross section,
the four superconducting coils are all arranged so that the coil axes have an angle within a range of more than −30° and less than 30° in the horizontal plane relative to a Y axis, the Y axis being perpendicular to the X axis,
the direction of the lines of magnetic force generated by the four superconducting coils have line symmetry about the cross section, and
in each of the first region and the second region, the two superconducting coils generate lines of magnetic force in opposite directions.