US 12,188,153 B2
Single-crystal pulling apparatus with saddle-shaped superconducting coils and single-crystal pulling method
Kiyotaka Takano, Annaka (JP); Kosei Sugawara, Nishigo-mura (JP); Hiroyuki Kamada, Nishigo-mura (JP); Takahide Onai, Nishigo-mura (JP); and Tomohiko Ohta, Shirakawa (JP)
Assigned to SHIN-ETSU HANDOTAI CO., LTD., Tokyo (JP)
Appl. No. 17/907,875
Filed by SHIN-ETSU HANDOTAI CO., LTD., Tokyo (JP)
PCT Filed Feb. 22, 2021, PCT No. PCT/JP2021/006610
§ 371(c)(1), (2) Date Aug. 29, 2022,
PCT Pub. No. WO2021/187017, PCT Pub. Date Sep. 23, 2021.
Claims priority of application No. 2020-046021 (JP), filed on Mar. 17, 2020; and application No. 2020-178960 (JP), filed on Oct. 26, 2020.
Prior Publication US 2023/0138632 A1, May 4, 2023
Int. Cl. C30B 15/20 (2006.01); C30B 30/04 (2006.01)
CPC C30B 30/04 (2013.01) [C30B 15/20 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A single-crystal pulling apparatus comprising:
a pulling furnace which has a heater and a crucible containing a molten semiconductor raw 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, the single-crystal pulling apparatus applying a horizontal magnetic field to the molten semiconductor raw material by energization to the superconducting coils to suppress convection of the molten semiconductor raw material in the crucible,
wherein the superconducting coils of the magnetic field generation device are saddle-shaped and are curved by a curvature larger than a curvature of a shape along an outer shape of the pulling furnace, two pairs of the saddle-shaped superconducting coils being arranged around the pulling furnace to face each other,
when axes running through centers of the pairs of the superconducting coils arranged to face each other are determined as coil axes,
the two coil axes in the two pairs of the superconducting coils are included in a single horizontal plane, and
when a direction of lines of magnetic force at the central axis of the pulling furnace in the horizontal plane is determined as an X axis, a center angle α having the X axis sandwiched between the two coil axes is 100 degrees or more and 120 degrees or less,
wherein a ratio of the curvature of the saddle-shaped superconducting coils to the curvature of the shape along the outer shape of the pulling furnace is 1.2 or more and 2.0 or less.