JPS63166785A - Apparatus for producing single crystal - Google Patents

Abstract

PURPOSE:To improve the yield and quality of a single crystal, by covering the bottom and a part of retaining part of the main body of a crucible in the production of a single crystal using Bridgman method. CONSTITUTION:The objective single crystal-production apparatus is an apparatus for producing a single crystal using Bridgman method and is provided with a crucible composed of a crucible main body 1 and a retaining part 3 connected to the main body 1. The bottom 2 of the main part 1 and a part of the retaining part 3 are covered with a heat-insulation cylinder 4 filled with a heat-insulation material 5 to prevent the lowering of the temperature. The yield and quality of single crystal can be improved by the use of the above apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Industrial Application The present invention relates to a heat-insulating structure for a crucible used when growing a single crystal by the Bridgman method.

(2) Prior Art When producing single crystals, the Bridgman method is generally used. In this Bridgman method, a raw material is placed in a crucible, the raw material is melted in the crucible, and then the crucible is moved vertically in an electric furnace with a predetermined temperature gradient in the vertical direction. This is a method of gradually solidifying raw materials to produce single crystals.

For single crystal growth using the Bridgman method, a V-bottomed platinum crucible is used as shown in Figure 3. It is equipped with storage nozzles 4 and 3 in which seed crystals can be placed.

(3) Problems to be Solved by the Invention When crystal growth is performed using the above-mentioned V-bottom platinum crucible, the temperature distribution inside the crucible during crystal growth is as shown by the broken line d in Fig. 4(b). , the temperature in the upper part of the crucible storage nozzle 3 and the lower end of the main body 1, that is, in the vicinity of the bottom part (2) becomes lower. Therefore, the temperature rise outside the vicinity of the bottom is large. Temperature drop near the bottom of this V.

■The rise in temperature outside the vicinity of the bottom prevents single-nucleus growth, which is crystal growth in the same direction as the seed crystal.

As a result, nuclei with different orientations tend to grow, resulting in a polycrystal with a defined orientation different from that of the primary crystal. Therefore, there is a problem that it leads to a decrease in single crystallization yield.

By the way, since it is difficult to commercialize these polycrystals with defined orientation, it is necessary to prevent polycrystals with defined orientation, improve the single crystallization yield, and grow larger crystals.

It is necessary to make the temperature distribution in the temperature decreasing section described above as smooth as possible, like the temperature distribution in the air furnace (shown by the solid line in FIG. 4(b)). One solution to this problem is to raise the crystal growth temperature. However, when the temperature is raised, impurities such as platinum and rhodium used in the crucible material are increasingly mixed into the raw material, making it difficult to obtain high-quality single crystals.

If the overall temperature is raised in this way, the yield of single crystallization will be improved, but another problem arises in that impurities are mixed in and good quality single crystals cannot be obtained.

An object of the present invention is to improve the yield of single crystallization.

Moreover, it is an object of the present invention to provide a manufacturing apparatus that can obtain high quality single crystals with less contamination of impurities.

(4) Means for Solving the Problems According to the present invention, the crucible body and the 9
In a production apparatus for producing single crystals by the Bridgman method, which includes a crucible having a storage section in which a seed crystal is housed, the method for producing oligocrystals among the crucibles described above is obtained.

(5) Examples The present invention will be explained below with reference to Examples.

As shown in FIG. 1(a), the crucible used in the present invention includes a cylindrical crucible body 1 with a V-shaped bottom 2 and a bottomed storage pipe 3 connected to the crucible body 1. . As shown in the figure, a heat insulating cylinder 4 is attached to a part of the V bottom part 2 and the storage nozzle 3 of the crucible, and the heat insulating cylinder 4 is filled with a heat insulating material 5.

When we investigated the temperature distribution inside this acupuncture point, we found that Fig. 4 (b)
The temperature distribution was as shown in a. ■There was no temperature drop at the bottom, and the temperature distribution was flat. When producing a single crystal, raw materials are filled into a crucible and melted, and then 3
Single crystals were obtained by lowering the crucible at a rate of ˜711 IllI/hr.

Figure 1 shows the yield of single crystals and the number of platinum particles in the single crystal after crystal growth using the production equipment according to the present invention.For comparison, when a conventional platinum crucible is used, ■ Shows the single crystal yield and the number of platinum particles in the single crystal when the bottom and part of the storage/arm part are covered only with a heat insulating tube (by the way, in order to improve the yield .

Since the single crystal was grown at a high temperature of 1700°C, the density λ of platinum particles mixed in the single crystal was as large as 30 particles/1M2 as shown in Fig. Since the production equipment was able to prevent the temperature inside the crucible from decreasing, it was possible to produce single crystals at a high yield of 80 to 90% as shown in Figure 2 even when crystals were grown at temperatures as low as 1650°C. moreover.

The density of platinum particles mixed in the single crystal can also be reduced to 5 particles/1M2 or less, compared to conventional methods.

(6) Effects of the Invention As described above, according to the single crystal manufacturing apparatus of the present invention,
Since it is possible to prevent a temperature drop near the bottom of the crucible body, the yield of single crystals is improved, and since the single crystal growth temperature can be lowered than before, it is possible to prevent platinum particles from being mixed into the single crystal. This makes it possible to efficiently grow high-quality single crystals.

[Brief explanation of the drawing]

Figure 1 (,) is a diagram showing the structure of the crucible used in the single crystal manufacturing apparatus according to the present invention, Figure 1 (b) is a diagram showing the relationship between crucible position and temperature, and Figure 2 is a diagram showing the single crystallization step. Figure 3 is a diagram showing the shape of the crucible; Figures 4 (,) and (b) are diagrams showing the crucible and the relationship between crucible position and temperature, respectively. be. Figure 1 (a) (b) Figure 2 Figure 3 Figure 4 (a) (b) Temperature

Claims (1)

[Claims] 1. In a manufacturing apparatus for producing a single crystal by the Bridgman method, which includes a crucible having a crucible body and a storage part connected to the crucible body, at least a part of the bottom of the crucible body and a part of the storage part of the crucible. 1. A single crystal production device characterized in that the crystal is covered with a heat insulating means.