Apparatus and method for growing oxide single crystals

Abstract

To provide an apparatus and method for growing a single crystal, using an oxide crucible formed of the same material as a raw material melt.SOLUTION: An apparatus for growing a single crystal includes: an apparatus body 10 including a cylindrical heat chamber 1, an oxide crucible 2 provided in the heat chamber, a high frequency induction coil 3 provided in the periphery of a side wall of the heat chamber and a cylindrical metal heater 5 built in the oxide crucible and induction-heated by the coil; and first, second and third polymerization chambers 20, 30 and 40 provided above the apparatus body, having the lower end side opening parts superimposed on the upper end side opening part of the heat chamber and moved by transfer means in the chamber. Openings 22 and 42 for crystal pulling shafts 21 and 41 and crystal storage parts 23 and 43 are provided in the first and third polymerization chambers; the second polymerization chamber includes raw material supply means 31; the upper end side opening part of the heat chamber and each lower end side opening part of the first, second and third polymerization chambers include partition plates 6, 24, 32 and 44 attachably / detachably provided; and a crystal can be taken from the oxide crucible without lowering a crucible temperature, and a crystal raw material can be added.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a growth apparatus and a growth method capable of continuously growing an oxide single crystal such as lithium tantalate by a pulling method.

Background Art

[0002] As a method for growing an oxide single crystal, a crucible filled with a raw material that becomes an oxide single crystal is heated to a high temperature to melt the raw material. After bringing a seed crystal into contact with the raw material melt surface in the crucible from above, the seed crystal is rotated and raised to grow an oxide single crystal having the same orientation as the seed crystal (also referred to as the Chokralski method). This pulling method is widely used.

[0003] In an apparatus for growing an oxide single crystal by the pulling method, as shown in FIG. 15, a high-frequency induction coil 101 is arranged around the side wall of a crucible 100. By passing a high-frequency current through the high-frequency induction coil 101, eddy currents are generated in the crucible 100, causing the crucible 100 to generate heat and melt the raw material. Further, as the pulling progresses, the upper part of the oxide single crystal is cooled through a seed rod (crystal pulling axis) 102. However, when the heating element is only the crucible 100, the temperature distribution in the single crystal during growth becomes large. Therefore, a metal ring-shaped reflector 103 is arranged at the open end of the crucible 100, and a metal after-heater 104 is arranged at the upper end of the crucible 100. In FIG. 15, reference numeral 105 denotes a seed crystal, reference numeral 106 denotes a raw material melt, reference numerals 107 and 108 denote heat insulating materials, reference numeral 109 denotes a CP crucible (porous alumina crucible), and reference numeral 110 denotes a heat insulating crucible stand.

[0004] By the way, in recent years, the market for oxide single crystals, particularly lithium tantalate, as surface acoustic wave device materials has been expanding, and the pulling length and diameter of single crystals have gradually increased to ensure production volume. Along with this increase in size, the crucibles used for crystal growth have become larger. <0​​Furthermore, since crucibles must be conductive to conduct high-frequency currents, and also have a high melting point to withstand high temperatures and do not degrade in an oxidizing atmosphere in order to melt the crystal raw materials, crucibles used for crystal growth are often made of precious metals such as iridium, platinum, and rhodium, or their alloys.

[0006] However, when growing single crystals using a precious metal crucible, there was a problem in that the crucible deformed. This is because the cylindrical precious metal crucible 100 shown in Figure 16(A) expands as shown in Figure 16(B) when the raw material is melted, and when it cools, the solidified part of the raw material molten 106 stretches and deforms as shown in Figure 16(C), which is due to the difference in expansion rates between the precious metal crucible and the oxide molten material.

[0007] To prevent deformation of this precious metal crucible, it is effective to grow long crystals in the straight section to reduce the number of times the molten raw material solidifies. However, when long crystals in the straight section are pulled up, the molten raw material solidifies at the bottom of the crucible because the molten level inside the crucible decreases as the crystal grows. Furthermore, the crucible generates heat, and the radiant heat from the crucible walls causes distortion, twisting, and other problems in the crystal being grown.

[0008] Therefore, Patent Document 1 proposes a crucible of precious metals in which a reinforced precious metal plate made of the same precious metal material as the crucible, to which zirconium oxide or the like has been added, is tightly attached to the outer circumference of the crucible body to prevent deformation of the crucible. Patent Document 2 proposes a growth device in which the periphery of the crucible is covered with a cylindrical molded insulating material such as alumina to suppress deformation of the crucible. Furthermore, Patent Document 3 proposes a crucible for single crystal growth in which a ring-shaped frame is fitted to the outer circumference of the side wall of the crucible to prevent deformation, and Patent Document 4 proposes an iridium crucible in which the thickness of the plate on the bottom of the crucible is thinner than the thickness of the plates on the sides to allow deformation to escape to the bottom side.

[0009] However, even with any of the countermeasures proposed in Patent Documents 1 to 4, it was difficult to prevent deformation of the crucible, and in particular, the amount of deformation of the crucible becomes large when growing large oxide single crystals, so a more effective countermeasure was needed.

[0010] Against this technological backdrop, focusing on the fact that lowering the crucible temperature when removing the grown crystal from the crucible or adding crystal raw materials to the crucible causes crucible deformation, Patent Document 5 proposes a growth apparatus using a pulling method that allows the grown crystal to be removed from the crucible without lowering the crucible temperature, and also allows crystal raw materials to be added to the crucible.

[0011] In other words, the growth apparatus described in Patent Document 5, as shown in Figure 17, consists of a main chamber 300 having a precious metal crucible 301 and a high-frequency induction coil 302 for inductively heating the precious metal crucible 301; a first upper chamber 400 provided above the main chamber 300 and having a temperature control heater 401 and a poling electrode (also used as a crystal pulling axis) 402; a second upper chamber 500 also provided above the main chamber 300 and having a temperature control heater 501 and a poling electrode (also used as a crystal pulling axis) 502; and a raw material charging unit 600a also provided above the main chamber 300 and supplying crystal raw materials to the precious metal crucible 301 in the main chamber 300. The first upper chamber 400, the second upper chamber 500, and the raw material charging unit 600a are movable by means of moving equipment not shown. In Figure 17, reference numeral 403 indicates a polling electrode, reference numeral 404 indicates a lower cover for the first upper chamber 400, and reference numeral 503 indicates a polling electrode, and reference numeral 504 indicates a lower cover for the second upper chamber 500.

[0012] Then, as shown in Figure 18(A), the first upper chamber 400 with the lower cover 404 removed is inserted into the main chamber 300 and crystal growth is performed by the pulling method. After the grown crystal 600 is housed in the first upper chamber 400 as shown in Figure 18(B), the first upper chamber 400 is pulled upward and withdrawn from the main chamber 300 as shown in Figure 18(C).

[0013] Next, as shown in Figure 19, the lower cover 404 is fitted into the opening of the first upper chamber 400 which has been pulled out from the main chamber 300. Then, the crystals 600 housed in the first upper chamber 400 are annealed and polled, and a raw material charge unit 600a is inserted into the main chamber 300 to supply the crystal raw material 601 to the precious metal crucible 301 inside the main chamber 300.

[0014] Next, while the annealing and polling processes of the first upper chamber 400 are being carried out, the second upper chamber 500, with its lid 504 removed as shown in Figure 20, is inserted into the main chamber 300, and crystal growth is performed using the pulling method with the second upper chamber 500.

[0015] Furthermore, according to the growth apparatus shown in Figure 17, in which a first upper chamber 400, a second upper chamber 500, and a raw material charging unit 600a are provided above the main chamber 300, as long as crystal growth is carried out continuously, the grown crystals can be removed from the precious metal crucible 301 without lowering the crucible temperature, and crystal raw materials can be added to the precious metal crucible 301, thereby preventing deformation of the crucible. [Prior art documents] [Patent Documents]

[0016] [Patent Document 1] JP-A-10-338593 (see claim 1) [Patent Document 2] Japanese Patent Publication No. 2020-164339 (see Claim 1) [Patent Document 3] Japanese Patent Publication No. 2019-112240 (see Claim 1) [Patent Document 4] Japanese Patent Publication No. 2012-250874 (see Claim 1) [Patent Document 5] Japanese Patent Publication No. 2009-007203 (see Claim 1, paragraph 0039) [Overview of the project]

Problems to be Solved by the Invention

[0017] When the growth apparatus described in Patent Document 5 is applied, as long as crystal growth is continuously carried out, it is certainly possible to prevent deformation of the crucible.

[0018] However, it is necessary to stop crystal growth due to maintenance inspection, etc. of the growth apparatus. Even if the number of stops is minimized, as long as a noble metal crucible is used, deformation cannot be suppressed. Therefore, a new growth apparatus replacing the growth apparatus described in Patent Document 5 is demanded. <​​​​​​​​​​​​​​​​​​​​​A partition plate for closing each opening is detachably attached to the upper end side opening of the cylindrical heating chamber and the lower end side openings of the first polymerization chamber, the second polymerization chamber, and the third polymerization chamber.

[0021] Also, the 2 invention according to the present invention is In the oxide single crystal growth apparatus according to the first invention, the partition plate has a two-layer structure of a metal material and a heat insulating material, The 3 invention is In the oxide single crystal growth apparatus according to any one of the first invention to the 2 invention, the oxide single crystal is any one of a lithium niobate single crystal, a lithium tantalate single crystal, and a yttrium aluminum garnet single crystal, The 4 invention is In the oxide single crystal growth apparatus according to any one of the first invention to the 3 invention, the cylindrical metal heater is made of any one of platinum, iridium, rhodium, or an alloy thereof, The 5 invention is In the oxide single crystal growth apparatus according to any one of the first invention to the 4 invention, a ceramic crucible that covers the outer bottom surface and the periphery of the side wall of the oxide crucible is provided.

[0022] Next, the 6 invention according to the present invention is In a method for growing an oxide single crystal using the growth apparatus according to the first invention, The crystal growth process involves overlapping the upper open end of a cylindrical heating chamber, which is closed with a partition plate, with the lower open end of a first polymerization chamber, which is also closed with a partition plate, then removing the partition plates to connect the space of the cylindrical heating chamber and the space of the first polymerization chamber, lowering a crystal pulling axis from the first polymerization chamber to grow an oxide single crystal by the pulling method, and then housing the grown oxide single crystal in the crystal housing section of the first polymerization chamber, after which the partition plates are reattached to the upper open end of the cylindrical heating chamber and the lower open end of the first polymerization chamber to close the upper open end of the cylindrical heating chamber and the lower open end of the first polymerization chamber, respectively, and moving the first polymerization chamber horizontally from the main body of the apparatus with the upper open end of the cylindrical heating chamber and the lower open end of the first polymerization chamber closed. The raw material supply process involves overlapping the upper open end of a cylindrical heating chamber, which is closed with a partition plate, with the lower open end of a second polymerization chamber, which is also closed with a partition plate, then removing the partition plates to connect the space of the cylindrical heating chamber and the space of the second polymerization chamber, introducing crystalline raw material from the second polymerization chamber into the oxide crucible, and inductively heating the cylindrical metal heater with a high-frequency induction coil to melt the introduced crystalline raw material, then reattaching the partition plates to the upper open end of the cylindrical heating chamber and the lower open end of the second polymerization chamber to close the upper open end of the cylindrical heating chamber and the lower open end of the second polymerization chamber respectively, and moving the second polymerization chamber horizontally from the main body of the apparatus with the upper open end of the cylindrical heating chamber and the lower open end of the second polymerization chamber closed, and The crystal growth process involves overlapping the upper open end of a cylindrical heating chamber, which is closed with a partition plate, with the lower open end of a third polymerization chamber, which is also closed with a partition plate; then removing the partition plates to connect the space of the cylindrical heating chamber and the space of the third polymerization chamber; lowering a crystal pulling axis from the third polymerization chamber to grow an oxide single crystal by the pulling method; and after housing the grown oxide single crystal in the crystal housing section of the third polymerization chamber, reattaching partition plates to the upper open end of the cylindrical heating chamber and the lower open end of the third polymerization chamber to close them, and then moving the third polymerization chamber horizontally from the main body of the apparatus with the upper open end of the cylindrical heating chamber and the lower open end of the third polymerization chamber closed. The method is characterized by continuously growing oxide single crystals by repeatedly performing a crystal growth process using the first polymerization chamber and a crystal growth process using the third polymerization chamber, with the above raw material supply process in between. The 7 The invention is The 6 In the method for growing oxide single crystals described in the invention, The apparatus is characterized by having a cooling step during the raw material supply step, or during the raw material supply step and the subsequent crystal growth step, in which the oxide single crystal in the crystal housing section of the first polymerization chamber or third polymerization chamber, which moves horizontally from the main body of the apparatus and whose lower end opening is closed by a partition plate, is cooled. Also, the 8 The invention is The 6 Invention or the 7 In the method for growing oxide single crystals described in the invention, The above oxide single crystal is characterized by being one of the following: lithium niobate single crystal, lithium tantalate single crystal, or yttrium aluminum garnet single crystal. [Effects of the Invention]

[0023] According to the oxide single crystal growth apparatus of the present invention, The apparatus has an oxide crucible, a high-frequency induction coil, and a cylindrical metal heater, and above the main body are a first polymerization chamber and a third polymerization chamber, each equipped with an opening for a crystal pulling axis and a crystal housing section, and a second polymerization chamber equipped with a raw material supply means. As long as crystal growth is performed continuously, the grown crystal can be removed from the oxide crucible without lowering the crucible temperature, and crystal raw materials can be added to the oxide crucible.

[0024] Furthermore, since an oxide crucible made of the same material as the raw material molten is used as a means of storing and holding the raw material molten, deformation of the crucible can be suppressed. Also, during the growth of oxide single crystals, the cylindrical metal heater is sandwiched between the raw material molten inside and the raw material molten outside the cylindrical metal heater, thus suppressing thermal deformation of the cylindrical metal heater.

[0025] Therefore, it has the effect of enabling the stable and continuous growth of oxide single crystals of the same quality. [Brief explanation of the drawing]

[0026] [Figure 1] Diagram illustrating the configuration of the cultivation device according to the present invention. [Figure 2] A diagram illustrating the configuration of the moving mechanism for horizontally moving the first polymerization chamber, the second polymerization chamber, and the third polymerization chamber. [Figure 3] An explanatory diagram showing the manufacturing process of the main body of the apparatus according to the present invention. [Figure 4] An explanatory diagram showing the manufacturing process of the main body of the apparatus according to the present invention. [Figure 5] An explanatory diagram showing the manufacturing process of the main body of the apparatus according to the present invention. [Figure 6] An explanatory diagram showing the crystal growth process according to the present invention. [Figure 7] An explanatory diagram showing the crystal growth process according to the present invention. [Figure 8] An explanatory diagram showing the crystal growth process according to the present invention. [Figure 9] An explanatory diagram showing the crystal growth process according to the present invention. [Figure 10] An explanatory diagram showing the crystal growth process according to the present invention. [Figure 11] This diagram illustrates the state in which the crystal pulling axis, which holds the oxide single crystal housed in the crystal housing section of the first or third polymerization chamber, is fixed by a fixing jig. [Figure 12] An explanatory diagram of the raw material supply means according to the present invention. [Figure 13] An explanatory diagram showing the raw material supply process according to the present invention. [Figure 14] An explanatory diagram showing the raw material supply process according to the present invention. [Figure 15] An explanatory diagram of a conventional growth method using a growth apparatus that utilizes a precious metal crucible as a means of storing and holding the molten raw material. [Figure 16] Figure 16(A) is a cross-sectional view of a precious metal crucible, Figure 16(B) is a cross-sectional view of the precious metal crucible during the melting of the added crystal raw materials, and Figure 16(C) is a cross-sectional view of the precious metal crucible after it has been deformed as the molten raw material has solidified. [Figure 17] Diagram illustrating the configuration of the cultivation device described in Patent Document 5. [Figure 18] Figures 18(A) to (C) are explanatory diagrams showing the process of growing oxide single crystals using the pulling method with the main chamber and first upper chamber of the growth apparatus described in Patent Document 5. [Figure 19] An explanatory diagram of the raw material charging unit of the growth apparatus described in Patent Document 5. [Figure 20] An explanatory diagram showing the process of growing an oxide single crystal by the pulling method using the main chamber and second upper chamber of the growth apparatus described in Patent Document 5. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described in detail below with reference to the drawings.

[0028] 1. Conventional cultivation equipment and cultivation methods (1) Conventional cultivation device and cultivation method using this device As a conventional crystal growth apparatus, as described above, a device is known that includes a chamber 200 (see Figure 15) containing a CP crucible (porous alumina crucible) 109, a crucible 100, an insulating crucible stand 110, a ring-shaped reflector 103, an afterheater 104, insulating materials 107 and 108, a seed rod (crystal pulling axis) 102, and a high-frequency induction coil 101. As for the crucible 100 used for high-temperature crystal growth, crucibles of high-melting-point metals such as tungsten and tantalum, precious metal crucibles such as platinum, rhodium and iridium, and non-metallic crucibles such as alumina, magnesia, carbon and PBN (Pyrolytic Boron Nitride) are known.

[0029] By the way, lithium niobate (LiNbO3: hereafter abbreviated as LN), lithium tantalate (LiTaO3: hereafter abbreviated as LT), yttrium aluminum garnet (Y3Al5O 12When growing oxide single crystals such as YAG (hereinafter abbreviated as YAG), tungsten, tantalum, and carbon, which are easily oxidized, cannot be used because an oxygen-containing growth atmosphere is required. Similarly, alumina and magnesia cannot be used because they react with the oxide melt, and PBN is expensive and difficult to use in creating large crucibles.

[0030] For this reason, when growing oxide single crystals, crucibles made of precious metals such as platinum, rhodium, and iridium are used, as these metals are not oxidized and do not crack, preventing the leakage of the raw material molten metal.

[0031] (2) Conventional challenges However, as shown in Figures 16(A) to (C), the precious metal crucible undergoes thermal expansion during the melting of the raw materials, and deforms when the residue of the molten raw materials solidifies due to the different thermal expansion rates of the oxide and the precious metal. Due to this deformation, in the case of high-frequency induction heating, the heat generation state changes, which alters the growth conditions, and as the deformation of the crucible progresses, a problem arises in that single crystals cannot be obtained.

[0032] Furthermore, even in the crystal growth apparatus described in Patent Document 5, which allows for the removal of grown crystals from the crucible without lowering the crucible temperature and also allows for the addition of crystal raw materials to the crucible, there is a problem in that, as long as a precious metal crucible is used, the deformation of the crucible cannot be suppressed because it is necessary to stop crystal growth for maintenance and inspection of the growth apparatus.

[0033] 2. The growth apparatus of the present invention The crystal growth apparatus of the present invention, which uses the pulling method (Czochralski method), is used for producing oxide single crystals such as LN, LT, and YAG grown in air or an oxygen-containing inert gas atmosphere. The Czochralski method is a method of growing a single crystal with the same orientation as the seed crystal by immersing the tip of a single crystal, usually processed into a rod shape and cut according to a certain crystal orientation, into a raw material molten with the same composition, and gradually pulling it up while rotating it.

[0034] To solve the problems of the past, the inventors have found an apparatus and method for growing oxide single crystals using an oxide crucible made of the same material as the raw material molten, as a means of storing and holding the raw material molten, as an alternative to a deformable precious metal crucible.

[0035] (1) Cultivation device (1-1) The cultivation device according to the present invention is As shown in Figure 1, a cylindrical heating chamber 1 with an open upper end, and an oxidizing chamber provided inside the cylindrical heating chamber 1. material The apparatus body 10 includes an oxide crucible 2 made of material and capable of storing and holding molten raw material, a high-frequency induction coil 3 provided around the side wall of a cylindrical heating chamber 1, and a cylindrical metal heater 5 incorporated inside the oxide crucible 2 and inductively heated by the high-frequency induction coil 3, with its upper end held by a heater fixing rod (fixing means) 4 attached to the cylindrical heating chamber 1. The apparatus body 10 is provided above the main body of the apparatus, and within the chamber (not shown), there are three polymerization chambers (not shown) which have a lower end opening that overlaps with the upper end opening of the cylindrical heating chamber 1, and which are each movable horizontally by a moving means (not shown), and, The first polymerization chamber 20 and the third polymerization chamber 40 are provided with openings 22 and 42 for crystal pulling shafts 21 and 41 and crystal housing sections 23 and 43 for housing grown oxide single crystals (not shown), and the second polymerization chamber 30 is provided with a raw material supply means 31 for supplying crystal raw materials into the oxide crucible 2 of the apparatus body 10, The upper end opening of the cylindrical heating chamber 1 and the lower end openings of the first polymerization chamber 20, second polymerization chamber 30, and third polymerization chamber 40 are detachably fitted with partition plates 6, 24, 32, and 44 that close each opening. Furthermore, the lower end 3a of the high-frequency induction coil 3 in the main body of the apparatus 10 is positioned below the lower end 5a of the cylindrical metal heater 5, so that the lower end 5a of the cylindrical metal heater 5 is also induction heated.

[0036] In Figure 1, reference numeral 7 denotes a ring-shaped reflector, reference numeral 8 denotes an afterheater, reference numeral 9 denotes a ceramic crucible (PC crucible), and reference numeral 10a denotes a support base. Reference numerals 25 and 45 denotes insulating material, reference numerals 26 and 46 denotes support rods that support insulating material 25 and 45, reference numeral 33 denotes insulating material, reference numeral 34 denotes a push rod that pushes out the crystalline raw material 31a inside the heat-resistant holding container 37, and reference numeral 35 denotes a container lifting shaft that moves the heat-resistant holding container 37 up and down.

[0037] (1-2) According to the cultivation device of the present invention, The apparatus body 10, which has an oxide crucible 2, a high-frequency induction coil 3, and a cylindrical metal heater 5, is equipped with a first polymerization chamber 20 and a third polymerization chamber 40, which have openings 22 and 42 for crystal pulling shafts 21 and 41 and crystal housing sections 23 and 43, and a second polymerization chamber 30 equipped with a raw material supply means 31. By repeating the crystal growth process using the first polymerization chamber 20 and the crystal growth process using the third polymerization chamber 40, with the raw material supply process using the second polymerization chamber 30 in between, it is possible to remove grown crystals from the oxide crucible 2 without lowering the crucible temperature and to add crystal raw materials to the oxide crucible 2.

[0038] Furthermore, since an oxide crucible 2 made of the same material as the raw material molten is used as a means of storing and holding the raw material molten, deformation of the crucible can be suppressed. Also, during the growth of the oxide single crystal, the cylindrical metal heater 5 is sandwiched between the raw material molten inside the cylindrical metal heater 5 and the raw material molten outside the cylindrical metal heater 5, so thermal deformation of the cylindrical metal heater 5 can also be suppressed.

[0039] Therefore, it has the effect of enabling the stable and continuous growth of oxide single crystals of the same quality.

[0040] (2) Means of transportation Next, as a moving means 50 provided within the chamber and for moving the first polymerization chamber 20, second polymerization chamber 30, and third polymerization chamber 40 in the horizontal direction, an example is provided in Figure 2, which consists of two arc-shaped running rails 51, 51 on which the first polymerization chamber 20, second polymerization chamber 30, and third polymerization chamber 40 are mounted with their lower end openings facing downwards, a shaft 52 erected in the center of the arc-shaped running rails 51, 51, a rotating body 53 that can rotate clockwise and counterclockwise (i.e., forward and reverse directions) around the shaft 52, and a rotating arm 54 that connects the rotating body 53 to each polymerization chamber 20, 30, and 40. In Figure 2, reference numeral 55 indicates a cooling support stand that supports the first polymerization chamber 20 or the third polymerization chamber 40 when the grown crystals contained in the crystal housing sections 23, 43 of the first polymerization chamber 20 or the third polymerization chamber 40 are being cooled.

[0041] (3) Manufacturing of the main body of the device The apparatus body 10, which constitutes a part of the cultivation apparatus according to the present invention and is housed in the chamber 60, is manufactured, for example, as follows.

[0042] First, as shown in Figure 3, the ceramic crucible (CP crucible) 9 incorporated into the cylindrical heating chamber 1 leaves an upper space 11. oxides Add material 12a. oxides As for material 12a oxides Material powder or oxides A material block is shown as an example.

[0043] Next, a cylindrical metal heater 5 is incorporated into the upper space 11 of the ceramic crucible (CP crucible) 9, and the upper end 5b of the cylindrical metal heater 5 is fixed by a heater fixing rod (fixing means) 4 attached to the cylindrical heating chamber 1.

[0044] Then, as shown in Figure 4, the cylindrical metal heater 5 is incorporated into the upper space 11 of the ceramic crucible (CP crucible) 9. oxides Material 12a is added to the inside of the cylindrical metal heater 5 and the upper space 11 of the ceramic crucible (CP crucible) 9. oxides Fill with material 12a.

[0045] Next, as shown in Figure 5, a ring-shaped reflector 7 is placed on the upper end 5b of the cylindrical metal heater 5, which is held by a heater fixing rod (fixing means) 4, and an afterheater 8 is placed on the ring-shaped reflector 7.

[0046] Then, the cylindrical metal heater 5 is inductively heated by the high-frequency induction coil 3 provided around the side wall of the ceramic crucible (CP crucible) 9, and the inside of the cylindrical metal heater 5 oxides Material 12a and the vicinity of the side wall and lower end 5a of the cylindrical metal heater 5 oxides The material 12a is melted to form a raw material molten liquid 12, and the portion away from the side wall of the cylindrical metal heater 5 and the portion away from the lower end 5a oxides The apparatus body 10 can be manufactured by flowing molten raw material 12 between materials 12a to form a continuous oxide layer 2c, and then forming an oxide crucible 2 having the oxide layer 2c on its inner surface and capable of storing and holding the molten raw material 12.

[0047] (4) Oxide crucibles and ceramic crucibles The above oxide layer 2c is present on the inner surface and oxides The oxide crucible 2, composed of the material, does not need to be composed entirely of a single crystal. It is preferable that the entire crucible be composed of a sintered body or polycrystalline body, but it may also be partially in powder form. Furthermore, the oxide layer 2c of the oxide crucible 2 is separated from the oxide layer 2c. oxides The unmelted portion of the material functions similarly to the insulating material 108 and insulating crucible stand 110 in the conventional growth apparatus shown in Figure 15.

[0048] Furthermore, as the material for the ceramic crucible that covers the outer bottom surface 2b and the surrounding side walls of the oxide crucible 2, sintered refractories such as alumina, zirconia, magnesia, and calcia are preferred.

[0049] (5) Metal heaters, ring-shaped reflectors, afterheaters The shape of the metal heater described above is arbitrary as long as high-frequency induction heating is possible. However, when growing high-quality crystals using the Czochralski method, it is desirable that the raw material melt has rotational symmetry with respect to the seed crystal. For this reason, it is preferable that the metal heater also has a rotationally symmetrical shape and is cylindrical.

[0050] Furthermore, the metal heater is preferably made of a material that does not oxidize in an oxygen-containing atmosphere and can perform high-frequency heating without cracking. Specifically, it is desirable to make it from platinum, iridium, rhodium, or alloys thereof.

[0051] Furthermore, as a means of fixing the upper end of the metal heater, a heater fixing rod 4 attached inside the cylindrical heating chamber 1 shown in Figure 5 is exemplified. The upper end of the metal heater is fixed by passing it through the rod 4, and it is preferable that there be 2 to 6 heater fixing rods 4.

[0052] Furthermore, the material of the ring-shaped reflector placed on the upper end of the metal heater, and the afterheater placed on the ring-shaped reflector, is preferably the same material as that of the metal heater, specifically, platinum, iridium, rhodium in elemental form, or alloys thereof.

[0053] (6) Partition plate As the material for the partition plate that closes the upper end opening of the cylindrical heating chamber 1 and the lower end openings of the first polymerization chamber 20, the second polymerization chamber 30, and the third polymerization chamber 40, a metal material such as SUS, which has excellent strength, is preferred. However, an insulating material is preferred to block radiant heat from the high-temperature molten raw material and pulled crystals. For this reason, it is preferable to have a two-layer structure of a metal material and an insulating material. As the insulating material, alumina, zirconia, calcia, etc. can be used, but alumina and calcia are preferred as lightweight materials. Also, as the metal material, Fe-based materials such as SUS can be used.

[0054] 3. The present invention's method for growing plants A method for growing oxide single crystals using the growth apparatus according to the present invention comprises the following crystal growth steps using the first polymerization chamber 20, the following raw material supply steps using the second polymerization chamber 30, and the following crystal growth steps using the third polymerization chamber 40. The method is characterized by continuously growing oxide single crystals by repeatedly performing the crystal growth process using the first polymerization chamber 20 and the crystal growth process using the third polymerization chamber 40, with the raw material supply process using the second polymerization chamber 30 in between.

[0055] The growth method of the present invention will be explained below with reference to the drawings.

[0056] (1) Crystal growth process in which the first polymerization chamber 20 is used (1-1) Overlapping process of cylindrical heating chamber 1 and first polymerization chamber 20 As shown in Figure 6, the lower end of the first polymerization chamber 20, which has a lower end closed by a partition plate 24, is superimposed on the upper end of the cylindrical heating chamber 1, which has an oxide crucible 2 inside in which the raw material molten liquid 12 is stored and whose upper end is closed by a partition plate 6.

[0057] (1-2) Removal process of partition plates 6 and 24 Next, the partition plates 6 and 24 are removed to connect the space of the cylindrical heating chamber 1 with the space of the first polymerization chamber 20, as shown in Figure 7. At the same time, the crystal pulling shaft 21, which is attached to a vertical movement and rotation mechanism (not shown), is lowered to bring the seed crystal 27 into contact with the raw material melt 12 of the oxide crucible 2. After that, as shown in Figure 8, the crystal pulling shaft 21 is rotated and raised to grow the oxide single crystal 70.

[0058] (1-3) Installation process for partition plates 6 and 24 Next, as shown in Figure 9, the grown oxide single crystal 70 is placed in the crystal housing section 23 of the first polymerization chamber 20. Then, as shown in Figure 10, the partition plates 6 and 24 are reattached to the upper opening of the cylindrical heating chamber 1 and the lower opening of the first polymerization chamber 20 to close the upper opening of the cylindrical heating chamber 1 and the lower opening of the first polymerization chamber 20, respectively. Furthermore, the crystal pulling shaft 21 is removed from the vertical movement and rotation mechanism so that the first polymerization chamber 20 can move horizontally. The crystal pulling shaft 21, which has been removed from the vertical movement and rotation mechanism, is fixed by the fixing jig 28 shown in Figure 11.

[0059] (1-4) Transfer process between the first polymerization chamber 20 and the second polymerization chamber 30 Next, with the upper end opening of the cylindrical heating chamber 1 and the lower end opening of the first polymerization chamber 20 closed, the first polymerization chamber 20 is moved from the main body 10 clockwise to the position of the cooling support base 55 using the moving means 50 shown in Figure 2. The standby second polymerization chamber 30 is also moved clockwise, and the lower end opening of the second polymerization chamber 30, which is closed by the partition plate 32, is aligned with the upper end opening of the cylindrical heating chamber 1. Then, the container lifting shaft 35 of the second polymerization chamber 30 is attached to the vertical movement and rotation mechanism (however, only the vertical movement mechanism operates and the rotation mechanism is stopped).

[0060] (1-5) Cooling process Next, during the raw material supply process in which the second polymerization chamber 30 is used, or during the crystal growth process in which the raw material supply process and the subsequent third polymerization chamber 40 are used, the oxide single crystal 70 in the first polymerization chamber 20, which has been moved to the cooling support stand 55, is cooled to a predetermined temperature while an oxygen-containing gas is flowed through the first polymerization chamber 20, and then removed from the first polymerization chamber 20. The first polymerization chamber 20 from which the oxide single crystal 70 has been removed is left as an empty polymerization chamber until the crystal growth process using the third polymerization chamber 40 is completed.

[0061] (2) Raw material supply process in which the second polymerization chamber 30 is used As an example of a raw material supply means 31 used in the raw material supply process, as shown in Figures 12 to 13, the main part of which is composed is a heat-resistant holding container 37 having a raw material supply port 36 at its lower end and containing crystalline raw material 31a inside, and which can be folded approximately in the middle, a push rod 34 for pushing out the crystalline raw material 31a inside the heat-resistant holding container 37, and a container lifting shaft 35 for moving the heat-resistant holding container 37 up and down. If a large amount of crystalline raw material 31a is supplied to the oxide crucible 2 at once, the molten raw material inside the oxide crucible 2 may be rapidly cooled, or the oxide crucible 2 may be damaged, so a structure that allows adjustment of the supply amount is preferable. As for the material of the heat-resistant holding container 37, a material that does not react with the molten raw material and is not prone to oxidation is preferable, and materials such as Ir, Pt, Rh and their alloys, or high melting point oxide materials such as alumina, zirconia, and calcia are preferred.

[0062] (2-1) Overlapping process of cylindrical heating chamber 1 and second polymerization chamber 30 As shown in Figure 13, the lower end of the second polymerization chamber 30, which has a raw material supply means 31 and a lower end closed by a partition plate 32, is superimposed on the upper end of the cylindrical heating chamber 1, which has an oxide crucible 2 in which the raw material molten 12 remains and whose upper end is closed by a partition plate 6. This superimposing process is performed in synchronization with the timing when the first polymerization chamber 20, which houses the oxide single crystal 70 in the crystal housing section 23 as described above, is moved to the position of the cooling support base 55 by the moving means 50.

[0063] (2-2) Removal process of partition plates 6 and 32 Next, the partition plates 6 and 32 are removed to connect the space of the cylindrical heating chamber 1 with the space of the second polymerization chamber 30, as shown in Figure 14. The heat-resistant holding container 37 is then lowered by the container lifting shaft 35 attached to the vertical movement and rotation mechanism and placed near the oxide crucible 2. Crystal material 31a is then introduced into the oxide crucible 2 from the raw material supply port 36 of the heat-resistant holding container 37, and the cylindrical metal heater 5 is induction heated by the high-frequency induction coil 3 to melt the crystal material 31a.

[0064] (2-3) Installation process of partition plates 6 and 32 After the raw material supply is complete, the heat-resistant holding container 37 is lifted by the container lifting shaft 35 and placed inside the second polymerization chamber 30. Then, the partition plates 6 and 32 are reattached to the upper opening of the cylindrical heating chamber 1 and the lower opening of the second polymerization chamber 30 to close the upper opening of the cylindrical heating chamber 1 and the lower opening of the second polymerization chamber 30, respectively. At the same time, the container lifting shaft 35 is removed from the vertical movement and rotation mechanism, allowing the second polymerization chamber 30 to move horizontally. The container lifting shaft 35, which has been removed from the vertical movement and rotation mechanism, is also fixed by a fixing jig, similar to the crystal lifting shaft.

[0065] (2-4) Transfer process between the second polymerization chamber 30 and the third polymerization chamber 40 Next, with the upper end opening of the cylindrical heating chamber 1 and the lower end opening of the second polymerization chamber 30 closed, the second polymerization chamber 30 is moved clockwise from the main body 10 by the moving means 50, and the standby third polymerization chamber 40 is also moved clockwise so that the lower end opening of the third polymerization chamber 40, whose lower end opening is closed by the partition plate 44, is superimposed on the upper end opening of the cylindrical heating chamber 1. Then, the crystal pulling shaft 41 of the third polymerization chamber 40 is attached to the vertical movement and rotation mechanism.

[0066] Furthermore, the second polymerization chamber 30, which has been moved by the transport means 50, remains in its new position until the crystal growth process using the third polymerization chamber 40 is completed, and the consumed crystal raw material 31a is replenished in the heat-resistant holding container 37.

[0067] (3) Crystal growth process in which the third polymerization chamber 40 is used (3-1) Overlapping process of cylindrical heating chamber 1 and third polymerization chamber 40 Similar to the case where the first polymerization chamber 20 is used, the lower end of the third polymerization chamber 40, which has a lower end closed by a partition plate 44, is superimposed on the upper end of the cylindrical heating chamber 1, which has an oxide crucible inside in which the raw material molten liquid is stored and whose upper end is closed by a partition plate 6. This superimposing process is performed in synchronization with the timing when the second polymerization chamber 30, which has finished supplying raw materials as described above, is moved by the moving means 50.

[0068] (3-2) Removal process of partition plates 6 and 44 Next, the partition plates 6 and 44 are removed to connect the space in the cylindrical heating chamber 1 with the space in the third polymerization chamber 40, and the crystal pulling shaft 41 attached to the vertical movement and rotation mechanism is lowered to bring the seed crystal 27 into contact with the raw material molten in the oxide crucible. After that, the crystal pulling shaft 41 is raised while rotating to grow an oxide single crystal.

[0069] (3-3) Installation process for partition plates 6 and 44 Next, after the grown oxide single crystal is placed in the crystal housing section 43 of the third polymerization chamber 40, the partition plates 6 and 44 are reattached to the upper opening of the cylindrical heating chamber 1 and the lower opening of the third polymerization chamber 40 to close the upper opening of the cylindrical heating chamber 1 and the lower opening of the third polymerization chamber 40, respectively. At the same time, the crystal pulling shaft 41 is removed from the vertical movement and rotation mechanism so that the third polymerization chamber 40 can move horizontally. The crystal pulling shaft 41, which has been removed from the vertical movement and rotation mechanism, is also fixed by a fixing jig, similar to the crystal pulling shaft 21.

[0070] (3-4) Transfer process between the third polymerization chamber 40 and the second polymerization chamber 30 Next, with the upper end opening of the cylindrical heating chamber 1 and the lower end opening of the third polymerization chamber 40 closed, the moving means 50 moves the third polymerization chamber 40 from the main body of the apparatus to the position of the cooling support base 55 in a counterclockwise direction. The standby second polymerization chamber 30 is also moved in a counterclockwise direction, and the lower end opening of the second polymerization chamber 30, which is closed by the partition plate 32, is aligned with the upper end opening of the cylindrical heating chamber 1. Then, the container lifting shaft 35 of the second polymerization chamber 30 is attached to the vertical movement and rotation mechanism (however, only the vertical movement mechanism operates and the rotation mechanism is stopped).

[0071] (3-5) Cooling process Next, during the raw material supply process in which the second polymerization chamber 30 is used, or during the crystal growth process in which the raw material supply process and the subsequent first polymerization chamber 20 are used, the oxide single crystals in the third polymerization chamber 40 that have been moved to the cooling support stand 55 are cooled to a predetermined temperature while an oxygen-containing gas is flowed through the third polymerization chamber 40, and then removed from the third polymerization chamber 40. The third polymerization chamber 40 from which the oxide single crystals have been removed is left as an empty polymerization chamber until the crystal growth process using the first polymerization chamber 20 is completed. [Examples]

[0072] The embodiments of the present invention will be described in detail below with reference to comparative examples (conventional examples).

[0073] [Example 1] 1. Growing apparatus according to Example 1 (1) Manufacturing of the main body of the device 10 In the cylindrical heating chamber 1 shown in Figure 3, a ceramic crucible (CP crucible) 9 with an inner diameter of 270 mm and an internal height of 340 mm is incorporated, leaving an upper space 11, and lithium tantalate powder ( oxides Material 12a was added.

[0074] Next, an iridium cylindrical metal heater 5 with an inner diameter of 170 mm, a height of 170 mm, and a thickness of 2 mm was installed in the upper space 11 of the ceramic crucible (CP crucible) 9, and the upper end 5b of the cylindrical metal heater 5 was fixed by a heater fixing rod 4 attached inside the cylindrical heating chamber 1.

[0075] Then, as shown in Figure 4, lithium tantalate powder is placed in the upper space 11 of the ceramic crucible (CP crucible) 9 into which the cylindrical metal heater 5 is incorporated. oxides Material 12a is added, and lithium tantalate powder is placed inside the cylindrical metal heater 5 and in the upper space 11 of the ceramic crucible (CP crucible) 9. oxides Material 12a was filled in.

[0076] Next, as shown in Figure 5, a ring-shaped reflector 7 was placed on the upper end 5b of the cylindrical metal heater 5, which was held by the heater fixing rod 4, and an afterheater 8 was placed on the ring-shaped reflector 7.

[0077] Then, the cylindrical metal heater 5 is inductively heated by the high-frequency induction coil 3 provided around the side wall of the ceramic crucible (CP crucible) 9, and the lithium tantalate powder inside the cylindrical metal heater 5 ( oxides Material) 12a and lithium tantalate powder near the side wall and lower end 5a of the cylindrical metal heater 5 ( oxides Material) 12a is melted to make raw material melt 12, and lithium tantalate powder is removed from the portion away from the side wall of the cylindrical metal heater 5 and the portion away from the lower end 5a. oxides The apparatus body 10 according to Example 1 was manufactured by flowing molten raw material 12 between material 12a to form a continuous oxide layer 2c, and forming an oxide crucible 2 having the oxide layer 2c on its inner surface and capable of storing and holding the molten raw material 12.

[0078] Furthermore, lithium tantalate powder ( oxides When melting material 12a to form the oxide layer 2c, the input power of the high-frequency induction coil 5 is set 10% higher than during crystal growth in order to increase the amount of molten material on the outside of the cylindrical metal heater 5. This allows lithium tantalate powder ( oxides The raw material molten liquid flows between the material 12a layers, forming a continuous oxide layer 2c.

[0079] Furthermore, the partition plate 6 that closes the open upper end of the cylindrical heating chamber 1 is a two-layer structure made of metal (SUS) and insulating material (alumina).

[0080] (2) First polymerization chamber 20 and third polymerization chamber 40 used for crystal growth The first polymerization chamber 20 and the third polymerization chamber 40, which have a lower end opening that overlaps the upper end opening of the cylindrical heating chamber 1 shown in Figure 1, and have openings 22 and 42 for crystal pulling axes 21 and 41 and crystal housing sections 23 and 43 for housing the grown oxide single crystals, and have insulating materials 25 and 45 supported by support rods 26 and 46 inside, are made of SUS cylindrical bodies with a height of 60 mm, and the partition plates 24 and 44 that close the lower end openings are made of a two-layer structure of metal material (SUS) and insulating material (alumina), similar to the cylindrical heating chamber 1.

[0081] (3) Second polymerization chamber 30 used for raw material supply The second polymerization chamber 30, which has a lower opening that overlaps the upper opening of the cylindrical heating chamber 1 shown in Figure 1, and has a raw material supply means 31 inside, and an insulating material 33 provided at the lower opening, is also made of a SUS cylindrical body, and the partition plate 32 that closes the lower opening is a two-layer structure of metal material (SUS) and insulating material (alumina), similar to the cylindrical heating chamber 1. The raw material supply means 31 consists of a heat-resistant holding container 37 which has a raw material supply port 36 at its lower end and contains crystalline raw material 31a inside and is bendable approximately in the middle, a push rod 34 that pushes out the crystalline raw material 31a inside the heat-resistant holding container 37, and a container lifting shaft 35 which is attached to an up-and-down movement and rotation mechanism (not shown) and moves the heat-resistant holding container 37 up and down.

[0082] (4) Means of transportation As shown in Figure 2, the moving means 50 according to this embodiment consists of two arc-shaped running rails 51, 51 on which the first polymerization chamber 20, the second polymerization chamber 30, and the third polymerization chamber 40 are mounted with the lower end open portion facing downwards, a shaft 52 erected in the center of the arc-shaped running rails 51, 51, a rotating body 53 that can rotate clockwise and counterclockwise around the shaft 52, and a rotating arm 54 that connects the rotating body 53 to each of the polymerization chambers 20, 30, and 40.

[0083] 2. Growth of lithium tantalate single crystals (1) Crystal growth using the first polymerization chamber 20 After overlapping the upper opening of the cylindrical heating chamber 1, whose upper opening is closed by a partition plate 6, with the lower opening of the first polymerization chamber 20, whose lower opening is closed by a partition plate 24, the partition plates 6 and 24 were removed to connect the space of the cylindrical heating chamber 1 with the space of the first polymerization chamber 20, and the crystal pulling shaft 21, which is attached to the vertical movement and rotation mechanism, was lowered to bring the seed crystal 27 into contact with the raw material molten in the oxide crucible 2. Thereafter, the crystal pulling shaft 21 was raised while rotating to grow a lithium tantalate single crystal with a diameter of 4 inches and a straight body length of approximately 50 mm.

[0084] Next, the grown lithium tantalate single crystal was placed in the crystal housing section 23 of the first polymerization chamber 20. Then, the partition plates 6 and 24 were reattached to the upper opening of the cylindrical heating chamber 1 and the lower opening of the first polymerization chamber 20 to close them, respectively. Furthermore, the crystal pulling shaft 21 was removed from the vertical movement and rotation mechanism so that the first polymerization chamber 20 could be moved horizontally.

[0085] Next, with the upper end opening of the cylindrical heating chamber 1 and the lower end opening of the first polymerization chamber 20 closed, the first polymerization chamber 20 was moved by the moving means 50 from the main body of the apparatus 10 to the position of the cooling support base 55 in a clockwise direction. The standby second polymerization chamber 30 was also moved in a clockwise direction, and the lower end opening of the second polymerization chamber 30, which was closed by the partition plate 32, was aligned with the upper end opening of the cylindrical heating chamber 1. Then, the vertical movement and rotation mechanism was attached to the container lifting shaft 35.

[0086] Then, the lithium tantalate single crystal in the first polymerization chamber 20, which had been moved to the cooling support stand 55, was cooled, and a lithium tantalate single crystal with a diameter of 4 inches and a straight body length of approximately 50 mm was extracted.

[0087] (2) Raw material supply using the second polymerization chamber 30 At the same time that the first polymerization chamber 20 is moved to the cooling support base 55, the lower end opening of the second polymerization chamber 30, whose lower end opening is closed by a partition plate 32, is superimposed on the upper end opening of the cylindrical heating chamber 1, whose upper end opening is closed by a partition plate 6. Then, the partition plates 6 and 32 are removed to connect the space of the cylindrical heating chamber 1 and the space of the second polymerization chamber 30. At the same time, the heat-resistant holding container 37 is lowered by the container lifting shaft 35 attached to the vertical movement and rotation mechanism to introduce the crystal raw material into the oxide crucible 2, and the cylindrical metal heater 5 is inductively heated by the high-frequency induction coil 3 to melt the crystal raw material.

[0088] Next, after the raw material supply is completed, the heat-resistant holding container 37 is lifted by the container lifting shaft 35 and placed inside the second polymerization chamber 30. Then, the partition plates 6 and 32 are reattached to the upper opening of the cylindrical heating chamber 1 and the lower opening of the second polymerization chamber 30 to close the upper opening of the cylindrical heating chamber 1 and the lower opening of the second polymerization chamber 30, respectively. At the same time, the container lifting shaft 35 is removed from the vertical movement and rotation mechanism so that the second polymerization chamber 30 can be moved horizontally.

[0089] Next, with the upper end opening of the cylindrical heating chamber 1 and the lower end opening of the second polymerization chamber 30 closed, the second polymerization chamber 30 was moved clockwise from the main body 10 using the moving means 50, and the standby third polymerization chamber 40 was also moved clockwise so that the lower end opening of the third polymerization chamber 40, which is closed by a partition plate 44, was superimposed on the upper end opening of the cylindrical heating chamber 1. Then, the vertical movement and rotation mechanism was attached to the crystal pulling shaft 41 of the third polymerization chamber 40. The second polymerization chamber 30, which was moved by the moving means 50, was kept on standby until the crystal growth process using the third polymerization chamber 40 was completed, and the consumed crystal raw material was replenished in the heat-resistant holding container 37.

[0090] (3) Crystal growth using the third polymerization chamber 40 In sync with the movement of the second polymerization chamber 30, the lower end opening of the third polymerization chamber 40, whose lower end opening is closed by a partition plate 44, was superimposed on the upper end opening of the cylindrical heating chamber 1, whose upper end opening is closed by a partition plate 6. Then, the partition plates 6 and 44 were removed to connect the space of the cylindrical heating chamber 1 and the space of the third polymerization chamber 40. At the same time, the crystal pulling shaft 41, which is attached to the vertical movement and rotation mechanism, was lowered to bring the seed crystal into contact with the raw material molten in the oxide crucible. After that, the crystal pulling shaft 41 was raised while rotating to grow a lithium tantalate single crystal with a diameter of 4 inches and a straight body length of approximately 50 mm.

[0091] Next, the grown lithium tantalate single crystal was placed in the crystal housing section 43 of the third polymerization chamber 40. Then, the partition plates 6 and 44 were reattached to the upper opening of the cylindrical heating chamber 1 and the lower opening of the third polymerization chamber 40 to close them, respectively. Furthermore, the crystal pulling shaft 41 was removed from the vertical movement and rotation mechanism so that the third polymerization chamber 40 could be moved horizontally.

[0092] Next, with the upper end opening of the cylindrical heating chamber 1 and the lower end opening of the third polymerization chamber 40 closed, the moving means 50 moves the third polymerization chamber 40 from the main body of the apparatus to the position of the cooling support base 55 in a counterclockwise direction. The standby second polymerization chamber 30 is also moved in a counterclockwise direction, and the lower end opening of the second polymerization chamber 30, which is closed by the partition plate 32, is aligned with the upper end opening of the cylindrical heating chamber 1. Then, the vertical movement and rotation mechanism is attached to the container lifting shaft 35.

[0093] Then, the lithium tantalate single crystal in the third polymerization chamber 40, which had been moved to the cooling support stand 55, was cooled, and a lithium tantalate single crystal with a diameter of 4 inches and a straight body length of approximately 50 mm was extracted.

[0094] (4) Continuous training Then, after supplying raw materials using the second polymerization chamber 30, the process of growing crystals using the first polymerization chamber 20 and the third polymerization chamber 40 was repeated 50 times. As a result, 48 lithium tantalate single crystals with a diameter of 4 inches and a straight body length of approximately 50 mm were grown, and the remaining 2 were lithium tantalate polycrystalline crystals.

[0095] Furthermore, after the continuous growth process was completed, no significant deformation was observed in the oxide crucible 2 inside the cylindrical heating chamber 1.

[0096] [Comparative Example (Conventional Example)] Using the conventional growth apparatus shown in Figure 15, and employing a crucible 100 made of iridium with a diameter of 170 mm and a height of 170 mm, a lithium tantalate single crystal with a diameter of 4 inches and a straight body length of approximately 50 mm was grown using the pulling method (Czochralski method).

[0097] After repeating the crystal growth process 30 times, lithium tantalate single crystals were obtained in 21 out of 30 attempts; single crystals were not obtained from the 22nd attempt onward.

[0098] This was because the crucible 100 had become significantly deformed after the 22nd use. [Industrial applicability]

[0099] According to the present invention, oxide single crystals of the same quality can be repeatedly and stably grown, and therefore has industrial applicability as an apparatus for growing oxide single crystals such as lithium tantalate single crystals used as surface acoustic wave device materials. [Explanation of Symbols]

[0100] 1. Cylindrical heating chamber 2. Oxide Crucible 2b Outer bottom surface 2c oxide layer 3. High-frequency induction coil 3a Bottom end 4. Heater fixing rod (fixing means) 5. Cylindrical metal heater 5a Lower end 5b Upper end 6 partition plates 7 Ring-shaped reflector 8 Afterheater 9. Ceramic Crucible (PC Crucible) 10 Main unit of the device 10a support stand 11 Upper space 12 Raw material melt 12a oxides material 20 First polymerization chamber 21 Crystal pulling axis 22 Aperture 23 Crystal housing section 24 partition plates 25 Insulation 26 Support rod 27 Seed Crystal 28 Fixing fixture 30 Second polymerization chamber 31 Raw material supply means 31a Crystal raw material 32 partition plates 33. Insulation 34 Push rod 35 Container lifting shaft 36 Raw material supply port 37 Heat-resistant holding container 40 Third polymerization chamber 41 Crystal pulling axis 42 Aperture 43 Crystal housing section 44 partition plates 45 Insulation 46 Support rod 50 Means of Transportation 51. Arc-shaped running rail 52 shaft 53. Solids of revolution 54 Rotating Arms 55 Cooling support stand 60 Chambers 70 Oxide single crystal 100 Crucible 101 High-frequency induction coil 102 Seed rod (crystal pulling axis) 103 Ring-shaped reflector 104 Afterheater 105 Seed Crystal 106 Raw material melt 107 Insulation 108 Insulation 109 CP Crucible (Porous Alumina Crucible) 110 Insulated Crucible Stand 200 chambers 300 Main Chamber 301 Precious metal crucible 302 High-frequency induction coil 400 First Upper Chamber 401 Temperature control heater 402 Polling electrode (also serves as a crystal pulling axis) 403 Polling electrodes 404 Lower lid 500 Second Upper Chamber 501 Temperature control heater 502 Polling electrode (also serves as a crystal pulling axis) 503 Polling electrodes 504 Lower lid 600 crystals 600a Raw Material Charging Unit 601 Crystallized raw materials

Claims

1. In an apparatus for growing oxide single crystals by the pulling method, The apparatus body comprises a cylindrical heating chamber with an open upper end, an oxide crucible provided within the cylindrical heating chamber and made of the oxide material and capable of storing and holding the raw material molten liquid, a high-frequency induction coil provided around the side wall of the cylindrical heating chamber, and a cylindrical metal heater incorporated within the oxide crucible and inductively heated by the high-frequency induction coil, with its upper end held by a fixing means provided above the oxide crucible. The apparatus is provided with a first polymerization chamber, a second polymerization chamber, and a third polymerization chamber within the chamber, each having a lower opening that overlaps with the upper opening of the cylindrical heating chamber and being movable horizontally by a moving means, and, The first and third polymerization chambers are provided with openings for crystal pulling axes and crystal housing sections for housing the grown oxide single crystals, and the second polymerization chamber is provided with a raw material supply means for supplying crystal raw materials into the oxide crucible of the apparatus body, An apparatus for growing oxide single crystals, characterized in that a partition plate for closing each opening is detachably attached to the upper end opening of the cylindrical heating chamber and the lower end openings of the first polymerization chamber, second polymerization chamber, and third polymerization chamber.

2. The apparatus for growing oxide single crystals according to claim 1, characterized in that the partition plate has a two-layer structure of a metal material and an insulating material.

3. The apparatus for growing oxide single crystals according to any one of claims 1 to 2, characterized in that the oxide single crystal is one of lithium niobate single crystal, lithium tantalate single crystal, or yttrium aluminum garnet single crystal.

4. The apparatus for growing oxide single crystals according to any one of claims 1 to 3, characterized in that the cylindrical metal heater is composed of platinum, iridium, rhodium, or an alloy thereof.

5. An apparatus for growing oxide single crystals according to any one of claims 1 to 4, characterized in that it comprises a ceramic crucible covering the outer bottom surface and the periphery of the side walls of the oxide crucible.

6. A method for growing an oxide single crystal using the growth apparatus described in claim 1, The crystal growth process involves overlapping the upper open end of a cylindrical heating chamber, which is closed with a partition plate, with the lower open end of a first polymerization chamber, which is also closed with a partition plate, then removing the partition plates to connect the space of the cylindrical heating chamber and the space of the first polymerization chamber, lowering a crystal pulling axis from the first polymerization chamber to grow an oxide single crystal by the pulling method, and then housing the grown oxide single crystal in the crystal housing section of the first polymerization chamber, after which the partition plates are reattached to the upper open end of the cylindrical heating chamber and the lower open end of the first polymerization chamber to close the upper open end of the cylindrical heating chamber and the lower open end of the first polymerization chamber, respectively, and moving the first polymerization chamber horizontally from the main body of the apparatus with the upper open end of the cylindrical heating chamber and the lower open end of the first polymerization chamber closed. The raw material supply process involves overlapping the upper open end of a cylindrical heating chamber, which is closed with a partition plate, with the lower open end of a second polymerization chamber, which is also closed with a partition plate, then removing the partition plates to connect the space of the cylindrical heating chamber and the space of the second polymerization chamber, introducing crystalline raw material from the second polymerization chamber into the oxide crucible, and inductively heating the cylindrical metal heater with a high-frequency induction coil to melt the introduced crystalline raw material, then reattaching the partition plates to the upper open end of the cylindrical heating chamber and the lower open end of the second polymerization chamber to close the upper open end of the cylindrical heating chamber and the lower open end of the second polymerization chamber respectively, and moving the second polymerization chamber horizontally from the main body of the apparatus with the upper open end of the cylindrical heating chamber and the lower open end of the second polymerization chamber closed, and The crystal growth process involves overlapping the upper open end of a cylindrical heating chamber, which is closed with a partition plate, with the lower open end of a third polymerization chamber, which is also closed with a partition plate; then removing the partition plates to connect the space of the cylindrical heating chamber and the space of the third polymerization chamber; lowering a crystal pulling axis from the third polymerization chamber to grow an oxide single crystal by the pulling method; and after housing the grown oxide single crystal in the crystal housing section of the third polymerization chamber, reattaching partition plates to the upper open end of the cylindrical heating chamber and the lower open end of the third polymerization chamber to close them, and then moving the third polymerization chamber horizontally from the main body of the apparatus with the upper open end of the cylindrical heating chamber and the lower open end of the third polymerization chamber closed. A method for growing oxide single crystals, characterized by continuously growing oxide single crystals by repeatedly performing a crystal growth process using the first polymerization chamber and a crystal growth process using the third polymerization chamber, with the above-mentioned raw material supply process in between.

7. The method for growing an oxide single crystal according to claim 6, characterized in that during the raw material supply process, or during the raw material supply process and the subsequent crystal growth process, the oxide single crystal in the crystal housing section of the first polymerization chamber or third polymerization chamber, which moves horizontally from the main body of the apparatus and whose lower end opening is closed by a partition plate, is cooled.

8. The method for growing an oxide single crystal according to claim 6 or 7, characterized in that the oxide single crystal is one of lithium niobate single crystal, lithium tantalate single crystal, or yttrium aluminum garnet single crystal.

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