JPH06128075A - Growing method for single crystal - Google Patents

Abstract

PURPOSE:To provide the subject method so designed that, in growing high- melting single crystal by pull method, iridium crucible breakage is prevented due to its abnormal expansion caused by the ambient gas trapped therein in solidifying residual melt after completing the growth. CONSTITUTION:On cooling a grown single crystal while immersing it in the residual melt even after completing its growth, the residual melt can be solidified while providing it with crystallinity, resulting in volume contraction of the melt and developing a gap between the crucible and the solidified melt, thus facilitating the ambient gas' escape and preventing crack developments etc. in the crucible without applying excessive stress thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for growing a high melting point single crystal such as yttrium silicate single crystal (hereinafter referred to as YSO single crystal) by a pulling method.

[0002]

2. Description of the Related Art Conventionally, the Czochralski method is generally used to grow a YSO single crystal. That is, in the Czochralski method, crystal raw materials such as yttrium oxide (Y ₂ O ₃ ) and silicon oxide (SiO ₂ ) are taken in a desired single crystal ratio, and the crystal raw materials are melted in a crucible to form a raw material melt. , A seed crystal is fixed to a sapphire seed crystal support rod, immersed in the raw material melt while applying a predetermined rotation, and pulled up at a predetermined speed to grow a single crystal, and at the end of the growth, grow from the raw material melt in the crucible The single crystal was completely cut off to lower the temperature and solidify. Expensive iridium is used as the crucible material.

[0003]

In the above-mentioned growing method, when the residual raw material melt is solidified in the iridium crucible, the raw material melt is solidified from the surface, so that a large amount of N ₂ or the like contained in the melt can be obtained. Atmospheric gas is confined inside and cannot be escaped in the upper direction in an attempt to escape to the outside.Therefore, pressure is applied to the side surface and downward direction of the remaining raw material melt, and stress is concentrated on the crucible wall. There was a problem that the crucible was easily damaged. An object of the present invention is to facilitate the escape of the atmospheric gas contained in the residual raw material melt and control the rapid volume change to prevent the crucible from being damaged.

[0004]

[Means for Solving the Problems] That is, in a method of pulling a single crystal from a melt by using a seed crystal to grow the single crystal, after the growth of the single crystal, the lower part of the grown single crystal is cooled while being attached to the remaining melt. Then, the problem is solved by a single crystal growing method characterized by preventing the crucible from being damaged by making the residual melt have crystallinity and solidifying.

[0005]

[Function] To crystallize the raw material melt by cooling and solidifying the remaining raw material melt after the growth of the YSO single crystal, with the grown single crystal lower part being attached to the residual raw material melt. The volume shrinks as compared to the state where the temperature is lowered and solidified, and a gap can be created between the crucible wall and the crucible wall, and the atmosphere gas such as N ₂ contained in the melt can be easily discharged to the outside. Since stress is not concentrated on the crucible, the damage of the expensive iridium crucible can be suppressed.

[0006]

EXAMPLES The present invention will be described below with reference to examples of the present invention and comparison with a conventional method for growing a single crystal. Figure 1 is Y
It is explanatory drawing which shows the schematic structure of the method of pulling up and growing SO single crystal. In FIG. 1, an iridium crucible 1 (hereinafter referred to as an Ir crucible) is filled with Y ₂ O ₃ and SiO _2, and the Ir crucible is heated by a high frequency induction heating coil 3 wound around the Ir crucible. , About 2050
Melting at a temperature of ℃. On the upper surface of the molten raw material, the growing single crystal 4 is pulled up while being rotated through the seed crystal 5 to form a crystal. Zirconia (ZrO ₂ ) powder 8 is filled between the Ir crucible 1 and the crucible heat insulating material 7, and the upper surfaces thereof are double-coated with heat insulating cylinders 9 and 10.
In the crystal materials according to the examples of the present invention, the temperature gradient on the melt surface during the crystal growth of the yttrium / silicon oxide single crystal is such that the temperature gradient is from 30 ° C. to 40 ° C. per 10 mm length. The structure of the furnace and the layout of the high frequency induction heating coil have been devised.

[0007]

[Embodiment 1] Next, an embodiment of the present invention will be specifically described. First, the raw materials Y ₂ O ₃ and SiO ₂ were weighed and mixed at a ratio of 1: 1 to obtain I of φ50 × 50 ^H × 1.5 ^t mm.
Fill the crucible and fire to make 3 fired bodies. Using this as a starting material, the temperature is raised and melted in a nitrogen atmosphere gas at a flow rate of 1 liter / min. After that, diameter 6mm, total length 200
10 to 20 rpm by attaching the seed crystal 4 set on the seed crystal support rod 6 of mm through the platinum / rhodium wire 11 to the melt.
At a speed of 1.5 to 2.5 mm / hr to grow crystals. As a result of lowering the temperature and solidification with the lower portion of the single crystal thus obtained attached to the residual raw material melt, no damage such as cracks was found in the iridium crucible, and reproducibility was good. When the lower part of the single crystal is separated from the raw material melt and the temperature is lowered and solidified as usual, 10
It was damaged with a 0% chance.

[0008]

As described above, according to the present invention, the generation of cracks in the crucible made of a relatively expensive iridium material is eliminated.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an outline of a method for growing a single crystal according to the present invention.

[Explanation of symbols]

 1 Iridium crucible 2 Yttrium / silicon oxide raw material 3 High-frequency heating coil 4 Single crystal 5 Seed crystal 6 Seed crystal support rod 7 Crucible heat insulating material 8 Zirconia powder 9,10 Heat insulating tube 11 Platinum / rhodium wire

Claims (1)

[Claims] 1. A method of pulling and growing a single crystal from a melt using a seed crystal, wherein after the growth of the single crystal, the grown lower part of the single crystal is cooled while being attached to the remaining melt, A method for growing a single crystal, wherein crucible damage is prevented by imparting crystallinity to and solidifying.