TW201422858A - Single-crystal manufacturing device - Google Patents

Abstract

The present invention provides a single-crystal manufacturing device that uses the Czochralski technique to manufacture a single oxide crystal from a molten liquid obtained by heating and melting a feedstock inside a crucible. Said single-crystal manufacturing device is provided with the following: a heater that heats the feedstock inside the crucible; and a main chamber in which the crucible is placed. This single-crystal manufacturing device is characterized in that the crucible is held by a graphite holding tool via a sacrificial material consisting of a metal having a high melting point. A single-crystal manufacturing device for manufacturing single oxide crystals in which the usable life of the crucible can be extended even with the use of a graphite holding tool is thus provided.

Description

Single crystal manufacturing device

The present invention relates to a single crystal manufacturing apparatus which is used in the production of an oxide single crystal such as a sapphire single crystal by a Czochralski (CZ) method.

In the manufacture of sapphire single crystals which are demanding as LED substrates, various growth methods are used, such as edge-defined film-fed growth method, Bridgman method. (Bridgman method) and Kyropoulos method.

In the recently developed Kjeldahl method, a sapphire single crystal is grown using a high melting point metal (tungsten, molybdenum, etc.), but the following problems occur: the c-axis crystal required for the LED substrate cannot be obtained, and is utilized. After the method of producing the a-axis crystallization, it is necessary to dig the crystal from the right angle to obtain the c-axis crystallization, and the productivity and the yield are very poor.

Therefore, recently, the Czochralski method (CZ method) has attracted attention due to the crystal growth of the c-axis, and high-frequency induction heating and resistance heating have been used, and various crystal growth methods have been tried. In the CZ method using a high-frequency induction heating method, a growth furnace is formed of a heat insulating material made of cerium and zirconia to carry out crystal growth, but since the price of ruthenium is very high, it is a hindrance to reduce the crystallization cost. factor. Therefore, it is expected to produce niobium using a high melting point metal (tungsten, molybdenum, etc.) which is inexpensive and versatile, and to reduce the cost by repeated use.

[Previous Technical Literature] (Patent Literature)

Patent Document 1: Japanese Patent Laid-Open Publication No. 2008-7353

Patent Document 1 discloses a method in which a crucible made of molybdenum or tungsten is supported by a crucible made of tantalum or tungsten. However, due to the use of high-priced tanning, it is limited in terms of cost reduction.

Therefore, in the single crystal manufacturing apparatus, a graphite material is used as a component in the furnace, and in particular, a graphite material is used to hold the high melting point metal crucible, which is advantageous in terms of cost reduction and thermal conductivity.

However, the inventors have found that there is a problem in such a device that since the high-melting-point metal material is carbonized (carburized) below the melting point of a raw material such as alumina, significant deterioration and deformation of the crucible occur, resulting in longevity. reduce.

Tungsten absorbs carbon in the range of 850 ° C to 1600 ° C and carbonizes, and molybdenum is carbonized at 1100 ° C or higher. Therefore, even at a temperature lower than the raw material, that is, the melting point of alumina of 2050 ° C, embrittlement and deformation due to carbonization cannot be avoided.

The high-melting-point metal ruthenium is made of a brittle material, and at a high temperature, the contact portion with the graphite material accelerates embrittlement due to carbonization, and deterioration such as cracking becomes remarkable. Therefore, the number of uses of ruthenium is significantly reduced, and the production cost is significantly increased.

The present invention has been made in view of the above problems, and an object thereof is to provide a single crystal manufacturing apparatus which can improve the life of a crucible even if a crucible holder made of graphite is used.

In order to achieve the above object, the present invention provides a single crystal manufacturing apparatus which produces an oxide single crystal by a melt obtained by heating and melting a raw material in a crucible by a CZ method, and the single crystal manufacturing apparatus is characterized in that: a heater and a main chamber for heating the raw material in the crucible, wherein the main chamber is provided with the crucible; and the crucible is held by a graphite holder through a sacrificial material of a high melting point metal .

In this way, if the crucible is held by the graphite retainer via the sacrificial material of the high melting point metal, since the crucible does not directly contact the graphite retainer, it is possible to suppress cracks and the like due to carbonization of the crucible. , can improve the life of the cockroach. Further, by using a graphite holder, the cost can be reduced. Therefore, the device can achieve both a reduction in cost and an increase in the life of the crucible.

In this case, it is preferable that the material of the crucible is at least one of tungsten, molybdenum, and rhenium as a main component.

If it is such a flaw, it is a device that can further reduce the cost because the material is relatively low.

In this case, it is preferable that the heater is a resistance heater.

In the apparatus of the present invention, such an electric resistance heater can be used.

In this case, it is preferable that the sacrificial material of the high melting point metal contains at least one of tungsten, molybdenum and rhenium as a main component.

In the case of such a sacrificial material, the sacrificial material of the device does not melt even at a high temperature, and becomes a device which does not contaminate the melt.

In this case, it is preferred that the oxide single crystal is a sapphire single crystal.

The apparatus of the present invention can be used as a device for manufacturing a sapphire single crystal.

In this case, it is preferable that the thickness of the sacrificial material of the high melting point metal is 2 mm or more.

With such a thickness, it is possible to surely prevent carburization of the crucible, and it is a device which can more effectively suppress the deterioration of the crucible.

As described above, according to the present invention, it is possible to simultaneously achieve an increase in the life of the crucible and a reduction in the cost of the apparatus.

10‧‧‧Single crystal manufacturing equipment

11‧‧‧ main chamber

12‧‧‧ gate valve

13‧‧‧Sub-chamber

14‧‧‧坩埚

15‧‧‧ melt

16‧‧‧Insulation materials

17‧‧‧ single crystal

18‧‧‧ Keeper

19‧‧‧坩埚 Support shaft

20‧‧‧Tip shaft

21‧‧‧ seed crystal holder

22‧‧‧heater

23‧‧‧Sacrificial materials

25‧‧‧ gas introduction tube

26‧‧‧ gas discharge pipe

27‧‧‧Vacuum pump

28‧‧‧ gas discharge pipe

Fig. 1 is a schematic view showing an example of a single crystal production apparatus of the present invention.

Fig. 2 is a view showing the deterioration state of the bottom of the crucible.

Hereinafter, the present invention will be described in detail with reference to the drawings as an example of the embodiment, but the present invention is not limited to the embodiment.

Fig. 1 is a schematic view of a single crystal production apparatus of the present invention.

The single crystal manufacturing apparatus 10 of the present invention in the first embodiment is a device for pulling up and producing an oxide single crystal 17 such as a sapphire single crystal by a melt 15 obtained by heating and melting a raw material in a crucible 14 by a CZ method. .

The single crystal manufacturing apparatus 10 includes a heater 22 that heats a raw material in the crucible 14 , a main chamber 11 in which a crucible 14 is disposed, and a sub chamber (lifting) A pull chamber 13 is attached to the main chamber 11 in such a manner as to be separable by the gate valve 12.

Further, as shown in Fig. 1, the apparatus 10 includes a gas introduction pipe 25 and a gas discharge pipe 26, and for example, in the case of single crystal growth, the gas can be introduced from the upper side of the sub-chamber 13 via the gas introduction pipe 25. An inert gas or the like is introduced thereinto, and the introduced gas is discharged to the outside of the furnace by the gas discharge pipe 26 at the bottom of the main chamber 11 by a vacuum pump 27 or the like. On the other hand, when a raw material or the like is added, the gate valve 12 is closed, and an operation such as adding a raw material is performed in the sub-chamber 13, and thereafter, the gas discharge pipe 28 for the sub-chamber and the gas introduction pipe 25 can be used to make the sub-chamber Gas exchange is carried out within 13.

Further, the apparatus 10 includes a heat insulating material 16 such as a graphite-based felt material, which surrounds the crucible 14 and the heater 22, a pulling shaft 20 for pulling up the single crystal 17, and a seed crystal holder 21 which holds the crystal A graphite holder 18 supporting the crucible 14 and a crucible support shaft 19 supporting the crucible 14 via a graphite holder 18.

In the apparatus 10 of the present invention, the crucible 14 is held by the graphite holder 18 via the sacrificial material 23 of the high melting point metal. For example, between the bottom of the crucible 14 and the upper surface of the graphite holder 18, the sacrificial material 23 is inserted and disposed.

In this way, if the crucible 14 is held by the graphite holder 18 via the sacrificial material 23 of the high melting point metal, the crucible 14 is held in a state where it does not contact the graphite holder 18, and the crucible 14 can be prevented. The cracking or the like caused by the carbonization deteriorates, and the life of the crucible 14 can be effectively improved. Further, by using the graphite material and the carbon composite material for the holder 18 holding the crucible 14 When made of graphite, the thermal conductivity is good and the cost can be reduced. Therefore, it is possible to achieve both a reduction in cost and an increase in the life of the crucible 14 at the same time. Here, when the graphite holder 18 supports the crucible 14 in such a manner as to surround the side surface of the crucible 14, the bottom surface of the crucible 14 and the side surface are not in direct contact with the graphite holder 18 by the sacrificial material 23. Keep it in the way.

In Fig. 2, an image showing the deterioration state of ruthenium in the case of contact with a graphite holder at a high temperature is shown. As shown in Fig. 2(a), when the crucible is directly held on the graphite holder, the bottom surface of the crucible is cracked and it is difficult to use it repeatedly. Further, as shown in Fig. 2(b), when the graphite retainer contacts the side surface of the crucible, a reaction occurs, which expands and deforms. In the present invention, deterioration of such defects can be effectively prevented.

Moreover, it is preferable that the heater 22 is a resistance heater, and the material of the crucible 14 is a metal crucible containing at least one of tungsten, molybdenum, and rhenium as a main component.

As the heater 22 of the apparatus 10 of the present invention, a high-frequency heater can be used, and ruthenium 14 can also be used. However, in the present invention, it is preferable to use inexpensive tungsten, molybdenum, and niobium as main components. After that. At this time, since the oxidation resistance is lower than that of ruthenium, the carbon heat insulating material 16 is used; since carbon is a good conductor, if the high frequency heating method is used, the thermal efficiency is inferior, and it is preferable to use a resistance heater. Thereby, the cost can be further reduced.

Preferably, the sacrificial material 23 of the high melting point metal is composed of at least one of tungsten, molybdenum and rhenium.

If such a sacrificial material 23 is used, it does not melt even at a high temperature, and there is no contamination of the molten metal 15 . At this time, it is better to sacrifice the material of the material 23 Set to be different from the material of 坩埚14. If it is the same material, the sacrificial material 23 may be welded (diffused and welded) to the bottom of the crucible due to the diffusion welding phenomenon, so that the crucible and the sacrificial material are made of different materials, which can further improve the life of the crucible 14 and sacrifice Material 23 can also be used repeatedly.

The sacrificial material 23 of the high melting point metal may be, for example, a disk shape, and preferably has a thickness of 2 mm or more, particularly 3 mm or more.

With such a thickness, carburization of the crucible 14 can be surely prevented, and deterioration of the crucible 14 can be more effectively suppressed. In this case, the upper limit of the thickness of the sacrificial material 23 is not particularly limited. However, since the sacrificial material 23 needs to be replaced when the deterioration is observed, for example, when the thickness is 20 mm or less, the operation is easy, and the cost due to replacement may be used. The rise inhibition is lower.

By using the single crystal manufacturing apparatus of the present invention as described above, an oxide single crystal such as a sapphire single crystal can be produced, and since helium can be repeatedly used, the cost of the apparatus can be reduced, and the manufacturing cost of the oxide single crystal can be reduced. .

[Examples]

Hereinafter, the present invention will be more specifically described by way of examples and comparative examples, but the invention is not limited to the examples.

(Examples, Comparative Examples)

The sapphire single crystal production was carried out using the single crystal production apparatus of the present invention shown in Fig. 1.

As an example, a tungsten and molybdenum disc (thickness: 2 mm) was inserted and placed between the bottom of the tungsten crucible and the graphite holder, and a molybdenum and tungsten disc (thickness: 2 mm) was inserted and placed in the molybdenum. The deterioration of the crucible in the above two cases was confirmed between the bottom of the crucible and the graphite holder.

In addition, as a comparative example, the single crystal was produced in the same manner as in the Example except that the tungsten and the molybdenum were directly held by the graphite holder, and the deterioration of the crucible was confirmed.

At this time, the size of the crucible was set to an outer diameter of 250 mm, a bottom plane portion diameter of 170 mm, and a height of 200 mm, and the size of the disc, that is, the disc, was set to have an outer diameter of 160 mm and a thickness of 2 mm. Further, the circular plate is inserted between the bottom of the crucible and the graphite holder in consideration of concentricity.

Table 1 is a result of confirming the deterioration state of the base of each of the materials of the crucible and the material of the disc (sacrificial material) in the examples, and the results of confirming the deterioration of the bottom of the crucible in the comparative example.

In the case of the embodiment in which the holding was carried out through the circular plate, the state of the bottom of the bottom after the completion of the pulling was observed, and the deterioration of the bottom was not observed.

In the case of the comparative example of the unpaved disc, even in one batch, the change in the bottom surface of the crucible was large, and cracking, deformation, and the like were found to be deteriorated.

Further, in the case where a molybdenum crucible was inserted into a disc made of molybdenum, no deterioration of niobium was observed, but the disc may be welded to the bottom of the crucible due to the diffusion welding phenomenon. Therefore, it is known that the crucible and the disc (sacrificial material) are made of different materials, and it can be used stably.

Further, the present invention is not limited to the above embodiment. Implementation above The embodiment is substantially the same as the technical idea described in the claims of the present invention, and the technical effects of the same effects are all included in the technical scope of the present invention.

10‧‧‧Single crystal manufacturing equipment

11‧‧‧ main chamber

12‧‧‧ gate valve

13‧‧‧Sub-chamber

14‧‧‧坩埚

15‧‧‧ melt

16‧‧‧Insulation materials

17‧‧‧ single crystal

18‧‧‧ Keeper

19‧‧‧坩埚 Support shaft

20‧‧‧Tip shaft

21‧‧‧ seed crystal holder

22‧‧‧heater

23‧‧‧Sacrificial materials

25‧‧‧ gas introduction tube

26‧‧‧ gas discharge pipe

27‧‧‧Vacuum pump

28‧‧‧ gas discharge pipe

Claims (19)

A single crystal manufacturing apparatus for producing an oxide single crystal by a melt obtained by heating and melting a raw material in a crucible by a CZ method, the single crystal manufacturing apparatus comprising: a heater and a main chamber; The heater heats the raw material in the crucible, and the main chamber is provided with the crucible; and the crucible is held by a graphite cage through a sacrificial material of a high melting point metal. The single crystal manufacturing apparatus according to claim 1, wherein the material of the crucible is at least one of tungsten, molybdenum and rhenium as a main component. The single crystal manufacturing apparatus according to claim 1, wherein the heater is a resistance heater. The single crystal manufacturing apparatus according to claim 2, wherein the heater is a resistance heater. The single crystal manufacturing apparatus according to claim 1, wherein the sacrificial material of the high melting point metal is at least one of tungsten, molybdenum and rhenium as a main component. The single crystal manufacturing apparatus according to claim 2, wherein the sacrificial material of the high melting point metal is at least one of tungsten, molybdenum and rhenium as a main component. The single crystal manufacturing apparatus according to claim 3, wherein the sacrificial material of the high melting point metal is at least one of tungsten, molybdenum and rhenium as a main component. The single crystal manufacturing apparatus according to claim 4, wherein the sacrificial material of the high melting point metal is at least one of tungsten, molybdenum and rhenium as a main component. The single crystal manufacturing apparatus according to claim 1, wherein the material of the sacrificial material of the high melting point metal is different from the material of the crucible. The single crystal manufacturing apparatus according to claim 2, wherein the material of the sacrificial material of the high melting point metal is different from the material of the crucible. The single crystal manufacturing apparatus according to claim 3, wherein the material of the sacrificial material of the high melting point metal is different from the material of the crucible. The single crystal manufacturing apparatus according to claim 4, wherein the material of the sacrificial material of the high melting point metal is different from the material of the crucible. The single crystal manufacturing apparatus according to claim 5, wherein the material of the sacrificial material of the high melting point metal is different from the material of the crucible. The single crystal manufacturing apparatus according to claim 6, wherein the material of the sacrificial material of the high melting point metal is different from the material of the crucible. The single crystal manufacturing apparatus according to claim 7, wherein the material of the sacrificial material of the high melting point metal is different from the material of the crucible. The single crystal manufacturing apparatus according to claim 8, wherein the material of the sacrificial material of the high melting point metal is different from the material of the crucible. The single crystal manufacturing apparatus according to any one of claims 1 to 3, wherein the oxide single crystal is a sapphire single crystal. The single crystal manufacturing apparatus according to any one of claims 1 to 3, wherein the sacrificial material of the high melting point metal has a thickness of 2 mm or more. The single crystal manufacturing apparatus according to claim 17, wherein the sacrificial material of the high melting point metal has a thickness of 2 mm or more.