JP2831906B2 - Single crystal manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal manufacturing apparatus suitable for manufacturing a single crystal useful as a substance such as an oxide magnetic material, an oxide dielectric material, and a semiconductor material.

[0002]

2. Description of the Related Art When a high-quality single crystal is produced by using a CZ (Czochralski) method known as a production method for growing a single crystal from a melt, the composition of the single crystal to be produced is determined by the melting point. Must be equal to the composition of the liquid. If the composition of the target single crystal is different from the composition of the melt, the composition of the single crystal to be grown changes, and as a result, strain occurs in the crystal, and a high-quality single crystal can be manufactured. Absent.

As is well known, the composition of a liquid phase and a solid phase, which coexist stably in a substance that decomposes and melts and a non-congruent substance, differ from each other. Absent. Therefore, the FZ (floating zone) method has conventionally been used for producing high quality single crystals of these substances. The production method of the decomposition melt by the FZ method is TSFZ (Traveling Solvent Floating Zon).
e) As a method of applying the principle of the TSFZ method to the FZ method of the condensing heating type, for example, a method of manufacturing a YIG (yttrium iron garnet) single crystal is described in JP-B-55-16120. It has been disclosed. Also Y
A method for producing a solid solution single crystal of IG is described in
-27479. Also, a method for producing a substance having a non-congruent composition is described in, for example, Journal of the Japanese Association for Crystal Growth Vol. 14 No. 2 (1987) 16
There is a proposal on pages 3-171.

Further, as a pulling-down method, a method of forming a molten zone between a seed crystal and a horizontal plate and growing a single crystal while dropping a raw material powder on the plate is disclosed in, for example, J. Mol.
Sci. Instr. , 42, p114 (196
Proposed in 5).

[0005]

In the conventional FZ method, the growth is started by specifying and controlling the composition of the melt at the initial stage of the growth. After the growth is started, the raw material rod having a constant composition is melted to grow the crystal, so that stable growth is possible only when growing a single crystal having the same amount and composition as the melted raw material.

[0006] However, in actual growth, various factors, particularly the melt penetrates into the raw material rod, change the amount and composition of the melt during growth.

[0007] The composition of a liquid layer stably coexisting with a substance that decomposes and melts or a non-congruent substance varies depending on the temperature. When growing a single crystal by the FZ method, the melt permeates into the grain boundaries of the polycrystal constituting the raw material rod due to the temperature gradient near the growth area, reacts with the polycrystal, and responds to the temperature at that location. Changes to the composition of the melt. Therefore, the composition and amount of the melt change. In particular, when a component not included in the single crystal is used for the melt, the composition and amount of the melt significantly change.

As described above, if the composition and amount of the melt change during the growth, the conventional method of melting a raw material rod having a constant composition cannot return the composition and the amount of the melt to a stable one. Impossible. Therefore, it is difficult to stably grow a high-quality single crystal.

Further, the conventionally known pulling-down method is a method of directly heating the plate. In this method, it is difficult to control the temperature in the vicinity of the growing area, so that the solid-liquid interface is disturbed and it is extremely difficult to grow a high-quality single crystal. Have difficulty.

In the case of increasing the diameter of a decomposed melt or a non-congruent substance such as YIG, the amount of a stable melt required when the diameter is small at the initial stage of growth and the amount of the melt when the diameter becomes large Since the amount of the stable melt is different, conventional methods such as the TSFZ method and the pull-down method, which constantly supply the raw material having the composition of the single crystal to be grown, cannot be grown.

In view of the problems and limitations of the conventional method as described above, the present invention makes it possible to easily adjust the composition and amount of the melt even if it becomes necessary during the growth. It is an object to provide a single crystal manufacturing apparatus capable of obtaining a single crystal of high quality.

[0012]

An object of the present invention is to provide a spheroid mirror, a heat source disposed at one focal point of the spheroid mirror, and a single crystal disposed at the other focal point of the spheroid mirror. In the condensing heating type single crystal manufacturing apparatus provided with a growing unit, the single crystal growing unit, a plate having a seed crystal and a fine hole horizontally placed above the seed crystal, and the seed crystal and the plate The problem is solved by a single crystal manufacturing apparatus characterized by comprising a molten zone formed between them and a pulverized substance supply pipe disposed above the plate.

[0013]

By using the manufacturing apparatus according to the present invention, when growing a decomposition melt or a non-congruent substance, only a necessary amount of raw material is supplied to the melt, and the raw material rod is brought into direct contact with the melt. Therefore, the melt does not penetrate into the raw material rod as in the prior art.

Further, by using the apparatus according to the present invention, the amount and shape of the melt during growth are observed in real time, and the amount of the melt decreases during growth, making it difficult to maintain the molten zone. In such a case, the molten zone can be returned to an optimal state by supplying a raw material having an appropriate composition and amount.

Further, when growing a large-diameter single crystal of a decomposition melt or a non-congruent substance by the apparatus according to the present invention, as the diameter of the crystal becomes larger, the raw material having an appropriate composition and amount is added while the raw material having an appropriate composition and amount is added. The amount can be increased, and the amount of the melt can be adjusted stably in accordance with the diameter, so that a stable large-diameter single crystal can be grown.

The plate used in the manufacturing apparatus is preferably made of a material which does not react with the melt, for example, platinum Pt for YIG.

The supply pipe also does not react with the melt and has a high melting point, for example, an alumina pipe is preferred.

The raw material to be supplied is more effective if it is sintered, reacted, and then pulverized, because it is stuck to the supply pipe and is not clogged.

[0020]

By performing the manufacturing process with the manufacturing apparatus according to the present invention, crystals can be grown stably even when the melt and the single crystal to be grown are not in equilibrium, and stable conditions (melt of the melt) can be obtained. Quantity and composition) can be found quickly.
It is also possible to increase the diameter of the decomposition melt by the TSFZ method.

[0021]

FIG. 1 shows an embodiment of the apparatus for producing and growing a single crystal according to the present invention. Heating furnaces are configured to face each other such that the respective focal points F ₀ , F ₀ of the two symmetric spheroidal mirrors 1, 2 coincide with each other. The reflecting surfaces of the spheroid mirrors 1 and 2 may be subjected to gold plating to reflect infrared rays at a high reflectance. Halogen lamps 3 and 4 are fixedly disposed in the vicinity of the other first and second focal points F ₁ and F ₂ of the spheroid mirrors 1 and 2. Further, at the position of the common focal point F ₀ , the solvent portion 5
There is a crystal rod 7 directly below the crystal rod 7 fixed to the upper end of a rotating shaft 6 extending vertically upward from below, and a platinum plate 8 (0.3 m) having pores above the solvent part 5.
(m thickness × 30 mm diameter) is positioned horizontally, and further above that, an alumina tube 9 (inner diameter 10 mm) is arranged. A space in which the alumina tube 9 and the crystal rod 7 are arranged and the halogen lamps 3 and 4 are partitioned by a quartz plate 10.
The sample space in which the alumina tube 9 and the crystal rod 7 formed by this section are arranged is filled with an atmosphere gas suitable for crystal production and growth. Plate 8 is quartz plate 1
It is fixed to 0. Using this device, the following Example 1
And 2 were performed.

EXAMPLE 1 A 50 g powder of yttrium oxide Y ₂ O ₃ , ferric oxide Fe ₂ O ₃ and bismuth oxide Bi ₂ O ₃ was used to obtain a composition in which 10 mol% of yttrium of YIG was replaced by bismuth. Adjusted and wet mixed with ethanol three times in an agate mortar. The raw material is packed in a rubber tube, and the hydrostatic pressure is 10
Press at 100kg / cm ² and 100mm at 10mm diameter
Into a cylindrical shape having a length of This was placed in a vertical tubular furnace composed of an alumina tube having an inner diameter of 30 mm and a length of 600 mm, and oxygen was passed through the inside of the tube at a rate of 0.5 liter / hr from below the tube. Sintering was performed for 1.5 hours, and oxygen was continued to flow until the sintering was completed to produce a raw material rod.

In addition, yttrium oxide Y
₂ O ₃ 5%, ferric oxide Fe ₂ O ₃ 50%, bismuth oxide B
10 g of powder adjusted to 30% of i ₂ O _{3 and} 15% of barium oxide was wet-mixed with 1 ml of ethanol in an agate mortar.
I went there. The raw material was packed in a rubber tube and pressed at a hydrostatic pressure of 1000 kg / cm ² to a diameter of 7 mm and a diameter of 40 mm.
Into a cylindrical shape having a length of This was placed in a vertical tubular furnace composed of an alumina tube having an inner diameter of 30 mm and a length of 600 mm, and oxygen was passed through the inside of the tube at a rate of 0.5 L / hr from below the tube. Sintering was performed for 1.5 hours, and oxygen was continued to flow until sintering was completed to produce pellets.

The raw material rods and pellets prepared as described above were each pulverized in an agate mortar into granules of about 1 mm.

In the apparatus for producing and growing a single crystal shown in FIG. 1, the alumina tube 9 is placed 10 m above the platinum plate 8.
m so that the tip would come near. 10mm diameter
The YIG grown in the (111) direction was fixed as a seed crystal on the rotating shaft 6 and 60 mg of the pellet obtained by the above operation was put on the seed crystal.

When the voltage of the halogen lamps 3 and 4 as heat sources was gradually increased, the pellets on the seed crystal were melted and turned into a liquid. Next, the rotating shaft 6 was raised to bring the liquid into contact with the plate 8. Then, as shown in FIG. 2, a molten zone was formed between the plate and the seed crystal. Further, the granular raw material prepared as described above was supplied through the alumina tube 9 onto the plate. Then, the melt in the melting zone and the raw material reacted through the pores of the plate 8, and the amount of the melt decreased. Then, the granular pellets were supplied onto the plate 8 while checking the amount of the melt. Then, a melt was formed at the upper part of the plate 8 and moved to the lower part of the plate 8 as a replenisher, and the amount of the melt in the melting zone formed by the plate 8 and the seed crystal was recovered.

By repeating the above operation and adjusting the amount of melt in the melting zone between the plate 8 and the crystal,
It was lowered at mm / hr. After growing for about 2 hours, about 1 mm of new crystal was crystallized on the seed crystal. Then, the voltage was lowered to separate the melt from the plate 8 and the crystal, and then cooled to room temperature over 8 hours.

The structure of the crystallized crystal is determined by the X-ray diffraction method.
Examination of the composition with MA revealed that YIG was bismuth substituted with 6% yttrium.

Comparative Example 1 Raw material rods and pellets were produced in the same manner as in Example 1.

The raw material rod obtained in this manner is fixed to the upper sample rotating shaft of a known floating zone method single crystal manufacturing apparatus employing an infrared condensing heating method, and similarly has a diameter of 10 m.
The YIG grown in the (111) direction at m was fixed as a seed crystal on the lower sample rotation axis, and 60 mg of the pellet obtained by the above operation was placed on the seed crystal. Oxygen gas was supplied as a growth atmosphere at a rate of 1.5 liter / hr through a fused quartz tube into a crystal growth chamber isolated from the outside air, and the upper rotating shaft and the lower rotating shaft were rotated at 33 rpm in opposite directions.

When the voltage of the heat source lamp was gradually increased, the pellet on the seed crystal was melted and turned into a liquid.
When the raw material rod is brought into contact with the liquid by lowering the upper rotating shaft, the liquid is gradually absorbed by the raw material rod, the liquid is rapidly reduced, and the remaining liquid is solidified, so that a molten zone cannot be formed. Was.

Under the same conditions, a molten zone could not be formed even when the amount of pellets was 200 mg. Also,
If more pellets were used, the liquid could not be maintained on the seed crystal and the liquid dropped.

Example 2 50 g of a powder composed of yttrium oxide Y ₂ O ₃ and ferric oxide Fe ₂ O ₃ was adjusted to a YIG composition, and wet mixing of ethanol was performed three times in an agate mortar. The raw material was packed in a rubber tube, pressed at a hydrostatic pressure of 1000 kg / cm ² , and formed into a column having a diameter of 10 mm and a length of 100 mm. This was placed in a vertical tubular furnace consisting of an alumina tube having an inner diameter of 30 mm and a length of 600 mm, and oxygen was passed through the inside of the tube at a rate of 0.5 liter / hr from below the tube. Sintering was performed for 1.5 hours, and oxygen was continued to flow until the sintering was completed to produce a raw material rod.

In addition, yttrium oxide Y
₂ O ₃ 15%, the powder 10g adjusted to ferric Fe ₂ O ₃ 85% oxidation was carried out once wet mixing ethanol in an agate mortar. The raw material is packed in a rubber tube,
It was pressed at 000 kg / cm ² and formed into a column having a diameter of 7 mm and a length of 40 mm. This is 30 mm in inner diameter and 6 in length
It was placed in a vertical tubular furnace consisting of a 00 mm alumina tube, oxygen was passed through the inside of the tube at 0.5 liter / hr from the bottom, and after 4 hours, it was sintered at 1300 ° C. for 1.5 hours. Pellets were produced by continuously flowing oxygen until the end of sintering.

The raw material rods and the pellets prepared as described above were each pulverized in an agate mortar into granules of about 1 mm.

The pellets obtained by the above operation were set in the apparatus shown in FIG. 1 in the same manner as in Example 1, and the voltage was gradually increased. Then, the pellet on the seed crystal melted out and became liquid. Next, the rotating shaft 6 was raised to bring the liquid into contact with the plate 8. As a result, a molten zone was formed between the plate 8 and the seed crystal. Next, the granular raw material prepared as described above was supplied onto the plate 8 through the alumina tube 9. At this time, the amount of the melt in the melting zone was reduced.
The amount was small compared to. In this state, set the voltage to 1
When the voltage was increased by 1.2 V over about 0 minutes, the amount of the melt increased. In this state, the rotating shaft 6 was lowered at 1 mm / hr.
When the raw material remaining as a solid on the plate 8 became small, the raw material was supplied through an alumina tube 9. When the amount of the melt became small, granulated pellets were supplied. When this operation was repeated and the amount of the melt was kept constant for 2 hours, a single crystal having the same diameter as the seed crystal was grown. When the voltage was then gradually increased in this state, the amount of the melt decreased. At this time, the granular pellets were supplied in a slightly larger amount to form a slightly larger melt than in the stable state. When this operation was repeated while increasing the voltage, the diameter of the crystal became large, and the diameter became about 15 mm after 5 hours.

Comparative Example 2 Raw material rods and pellets were produced in the same manner as in Example 2.

The raw material rod obtained in this manner was fixed to the upper sample rotating shaft of a known floating zone method single crystal manufacturing apparatus employing an infrared light heating method, and similarly, the diameter was 10 m.
The YIG grown in the (111) direction at m was fixed as a seed crystal on the lower sample rotation axis, and 60 mg of the pellet obtained by the above operation was placed on the seed crystal. Oxygen gas was supplied as a growth atmosphere at a rate of 1.5 liter / hr through a fused quartz tube into a crystal growth chamber isolated from the outside air, and the upper rotating shaft and the lower rotating shaft were rotated at 33 rpm in opposite directions.

When the voltage of the heat source lamp was gradually increased, the pellets began to melt and became liquid. The raw material rod was brought into contact with the liquid by lowering the upper rotating shaft, and a molten zone was formed between the raw material rod and the seed crystal. In order to increase the diameter, the upper sample rotation axis is 3 mm / hr, and the lower sample rotation axis is 1 mm / hr.
Lowered at hr. About 30 minutes thereafter, the amount of the melt in the melting zone decreased, and the width of the melting zone became narrower. After a while, the raw material rod and the seed crystal came into contact in the melting zone, and the melt dripped due to the vibration.

[Brief description of the drawings]

FIG. 1 is a schematic view of a condensing heating type single crystal manufacturing apparatus according to the present invention.

FIG. 2 is a conceptual diagram showing how a single crystal is manufactured in the apparatus of FIG.

[Explanation of symbols]

 1, 2 spheroid mirror 3, 4 heat source 5 solvent part 6 rotation axis 8 plate 9 supply pipe

Claims (1)

(57) [Claims] 1. A condensing device comprising: a spheroid mirror; a heat source disposed at one focal point of the spheroid mirror; and a single crystal growing unit disposed at the other focal point of the spheroid mirror. In the heating type single crystal manufacturing apparatus, the single crystal growing unit, a plate having a seed crystal and a fine hole horizontally placed above the seed crystal, and a molten zone formed between the seed crystal and the plate Wherein a pulverized material supply pipe is disposed above the plate.