JPS60239390A - Process for holding seed crystal for growing single crystal - Google Patents

Abstract

PURPOSE:To hold a seed crystal securely even in a case for growing a large sized single crystal by fitting a tapered notched part expanded toward the top end of a rotary shaft at the bottom part of the rotary shaft to a tapered part of a seed crystal, and surrounding the fitted part with a cylindrical body. CONSTITUTION:A tapered notched part 12 expanded toward an end of a bar- shaped rotary shaft 11 is provided to the bottom of the rotary shaft 11. Further, a tapered part 14 which can be fitted to said notched part 12 is provided to a side surface of square columnar seed crystal 13. The notched part 12 is fitted to the tapered part 14, and the seed crystal 13 is attached to the rotary shaft 11, and the rotary shaft 11 and the seed crystal 13 are surrounded by a cylindrical body 15 at the fitted part. 16 in the figure is a retaining wire for preventing sliding down of the seed crystal 13. By this constitution, sliding down of the seed crystal is surely prevented, and the seed crystal, even for the growth of a large- sized single crystal, is definitely retained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for holding a seed crystal used for single crystal growth by a rotational pulling method.

Most semiconductor single crystals or oxide single crystals that make up integrated circuits, optical communication devices, etc. are manufactured by the rotational pulling method, and in recent years their shapes have become larger. It has even reached the point where it is manufactured. When growing such a large single crystal, it is necessary to securely attach the seed crystal to the rotating shaft so that it can support the weight of the grown crystal and maintain rotation.

Conventionally, when growing a small single crystal, as shown in FIG. 1, a prismatic seed crystal 2 was housed in a fan-shaped cutout at the lower end of a rotating shaft 1, and a metal wire 3 was wound around the seed crystal to hold the seed crystal.

However, if this holding method using a metal wire is applied directly to the case of growing a large single crystal, the metal wire will loosen due to the tensile force due to the weight of the grown crystal and expansion due to high temperature, resulting in the seed crystal falling off and the grown crystal. At the same time, there were many accidents involving falling into the melt.

Furthermore, when a high-frequency heating method is used to prepare the melt, the rotating shaft must be made of a non-metallic material such as an oxide sintered body, but the sintered body is relatively difficult to process. For example, when providing the notch shown in FIG. 1, the machining is complicated.

An object of the present invention is to provide a method that can reliably hold a seed crystal even when growing a large single crystal by a rotational pulling method.

Another object of the present invention is to provide a method that can securely hold a seed crystal by performing relatively simple processing on a rotating shaft or the like.

The above purpose is to fit a seed crystal having a tapered part that fits into the notch into a rotating shaft having a thick taper-like notch at the bottom, and to fit this fitted part into a rotating shaft when growing a single crystal by the rotational pulling method. This is achieved by a method for holding a seed crystal for single crystal growth, characterized in that the rotating shaft and the seed crystal are surrounded by a cylindrical body.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a diagram showing an example of the shape of a rotating shaft and a seed crystal used in the present invention. A notch 12 in the shape of a tapered shaft is provided at the bottom of the rotary shaft 11 in the shape of a round rod, and a tapered portion 1 that fits into the notch 12 is provided on one side of the prismatic seed crystal 1°3.
4 is provided. The notch 12 and the chip/base 14 can be easily obtained by cutting, and even if the rotating shaft 11 is a sintered body of alumina, zirconia, etc., the machining is not complicated, and the splintered seed crystal can be used as a conventional prismatic seed. It is possible to use crystals.
1, as shown in FIG.
2 and Q/9 portion 14, the seed crystal 13 is brought into contact with the rotating shaft 11, and the rotating shaft 11 and the seed crystal 1 are connected at this fitting part.
3 and are surrounded by the cylindrical body 15. The cylindrical body 15 can be made of metal, sintered oxide, or the like. In the figure, reference numeral 16 denotes a mooring wire for further preventing the seed crystal 13 from being worn down. In this way, the Theno base portion 14 and the cylindrical body 16
If the seed crystal 13 is held using the rotation shaft 11, the seed crystal 13 is held between the rotation shaft 11 and the cylinder 15 near the lower end of the rotation shaft 11, and the seed crystal can be reliably prevented from falling.

According to the method of the present invention, for example, the diameter is 80 m + and the length is 150 m.
When growing a large single crystal such as a TrrM lithium niobate single crystal weighing 5 kg, the seed crystal can be held securely.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a conventional method of holding a seed crystal, Fig. 2 is a diagram showing an example of the shape of the rotating shaft and seed crystal used in the present invention, and Fig. 3 is a state in which the seed crystal shown in Fig. 2 is held. FIG. 1.11... Rotating axis, 2.13... Seed crystal, 3...
・Metal wire, 12... Notch, 14... 4 pieces of steel,
15... Cylindrical body, 16... Mooring wire. Chest 1

Claims (1)

[Claims] When growing a single crystal by the rotational pulling method, a seed crystal having a tapered part that fits into the notch is fitted onto a rotating shaft that has a thick tip-shaped notch at the bottom, and the seed crystal is connected to the rotating shaft at this fitted part. A method for holding a seed crystal for single crystal growth, comprising surrounding the seed crystal in a cylindrical body.