JPS5836997A - Producing device for single crystal - Google Patents

Abstract

PURPOSE:To grow a long single crystal by using double crucibles, supplying a raw material from an automatic raw material supplying device into the outer crucible and pulling the single crystal by using the inner crucible connected to the outer crucible through melt flow holes. CONSTITUTION:The weight of a melt 16 which is melted by induction heating by a high frequency coil provided on the outer side of a protecting tube 7 is weighed with a load cell 9, and said weighing is interlocked to a raw material supplying device 12, whereby the weight of the melt 16 in double crucibles 1 is maintained at a set weight automatically. While a holding bar 11 is rotated in an inner crucible 4, the bar is pulled upward and a single crystal is pulled up from the melt 16 by the seed crystal 10 attached to the tip of the rod 11. According to said device, there is no possibility for deposition of the unmolten raw material onto the crystal under pulling up, and since the level of the melt is maintained constant, the growth of the long single crystal is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a single crystal manufacturing apparatus equipped with an automatic raw material supply device.

Various single crystals are used in parts for electronic devices. For example, lithium niobate (L) is used as a substrate for surface acoustic wave devices.
iNbOs) = Lithium tantalate (LiTaOs)
) etc. are also used as substrates for magnetic bubble elements (Gd, Gap Ot*).
), etc. So these crystals have a melting point of LI
1253°C for NbOs.

In the case of L I T a O@, the temperature is as high as 1650℃, so high melting point precious metals such as platinum (PT), iridium (!R), or platinum-rhodium alloy (Pt-Rhl) are used as crucibles, each at a temperature close to the melting point of the crystal to be grown. A sintered body powder mixed in a stoichiometric ratio with silicate is placed in a crucible together with a flux and melted by high frequency heating, while a single crystal is grown by a pulling device using a seed crystal.

In this case, the crystal substrate needs to be as large as possible from the viewpoint of batch production of electronic circuits, and therefore crystals are grown using crucibles with a large diameter. Longer lengths are desired from the viewpoint of lower manufacturing costs.

However, when using a normal crucible, its capacity is limited,
Therefore, it is difficult to grow long crystals with large diameters.

The purpose of the present invention is to develop a manufacturing device for growing a long single crystal.As a method, the crucible for melting the raw material has a double structure, and the raw material powder is supplied to the outer crucible by an automatic feeding device to grow the crystal. It is possible to increase the length by keeping the amount of elongation constant.

The automatic feeder for raw materials is already known, such as a metal evaporation device.The device according to the present invention is characterized in that it performs crystal growth in conjunction with a load cell, and also has a double Crucibles are also known, but the conventional purpose is to specify the diameter of the crucible used for crystal growth, and because it is easy to adjust the crystal growth, the capacity can be increased compared to conventional crucibles by providing an inner crucible with holes for the flow of melt. The present invention also realizes a crucible with a small apparent capacity, and the main purpose of the present invention is to prevent the separately supplied raw material powder from depositing on the crystal during direct growth of a single crystal. It is said that

Hereinafter, the present invention will be explained using LiNbO5 single crystal growth as an example.

FIG. 1 is a block diagram of a single crystal production apparatus according to the present invention, and FIG. 2 is a perspective view of a double crucible I used therein.

An inner crucible 4 with a communicating hole 3 is formed, in this case PT.

This double crucible IKdLINbOs') raw material powder is placed in a predetermined weight.

This is LiNb0. The raw material powder is lithium carbonate (x, s
, Cow)
were mixed in a stoichiometric ratio of 0.94:117) and heated to 1ooo℃.
It is made from pulverized material after being sintered nearby.

As shown in the figure, the double crucible 1 carrying the
d There is a protective tube 7 made of transparent quartz, Vycor glass, etc., and a high frequency coil 8 is placed on the outside of the protective tube 7, so that induction heating is performed by a high frequency power source.

In this way, the total weight of the refractory porcelain 6 with the double crucible 1 in the center f15 is set as a trap so that it can be measured even during crystal growth using the dowel cell 9.In this embodiment, the measurement accuracy is a maximum weight of 20
It has a detection accuracy of 0.5g per kg.

Next, the seed crystal for pulling a single crystal is secured using a holding rod 11KPt-Rh, such as a 10 #i naphiya or aluminum holder, and after hanging Ks in the melt, the holding rod 11 is rotated from the crystal pulling atK. However, by pulling the crystal, a liquid-phase grown single crystal can be obtained.

Next, the raw material supply device 12 according to the present invention is installed outside the furnace, and the tip of the supply pipe 15 passes through the holes provided in the outer cover 13 and the inner cover 14 to the upper part of the outer crucible 2. The outer crucible is now ready to be supplied with 2KI material.

The main point of this device having such a configuration is that the weight of the molten material 16 in the double crucible 1 is weighed by the load cell 9 and is linked to the raw material supply device 12. The weight is automatically maintained at the set weight value.

For this purpose, it is necessary that the raw material supplied from the raw material supply device 12 is smoothly supplied to the outer 1 Ift# pot 2 for 1 second through the supply pipe, and for ξ, a vibrator is required in the supply pipe 15. Apply slight vibration using
Since the temperature of the melt exceeds 1250° C., it is necessary that the supply pipe 15 in the furnace be made of PT.

When pulling a single crystal from a seed crystal using the liquid phase method in C~, the temperature maintenance of the melt 16, the rotation speed of the holding rod 11, the pulling speed 1, etc. are important factors for single crystal growth. Adjustment is difficult and the temperature of the t-stage treatment is as high as 1200° C. or higher, and therefore, long crystals have been desired, but conventional crystal growth has not been carried out by automatic supply of raw materials.

The present invention uses a double crucible to prevent the raw materials from being deposited on the unmelted crystals being pulled when feeding them into the melt 16, thereby preventing the growth of the defective crystals described above. The advantage of 4I lies in that the liquid level is kept constant by interlocking the liquid cell 9 and the raw material supply device 12 to prevent fluctuations in the melt liquid level, and by implementing the present invention, It has become possible to grow single crystals that are much longer than before.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a single crystal manufacturing apparatus according to the present invention, and FIG.
The figure is a perspective view of a double crucible used in this device. In the figure, 1#i double crucible, 2 outer crucible, 3 communicating hole, 4 inner crucible, 9 load cell, Io#i seed crystal, 11 holding rod, ]2 raw material supply device, 15 supply pipe , 16 is a melt. Figure 1: 2TAS

Claims (1)

[Claims] In a single crystal growth device that grows a single crystal by a pulling method using a seed crystal from a melt melted by high-frequency heating, a double crucible is used as a crucible for melting raw materials, and raw materials are supplied to an outer crucible by an automatic raw material supply device. A single-crystal manufacturing device that supplies crystals and pulls crystals using inner crucibles that are interconnected through melt flow holes.