JP2002226299A - Apparatus and method for manufacturing single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing apparatus for a single crystal wherein cooling of the single crystal and growing of the subsequent single crystal are carried out at the same time. SOLUTION: The manufacturing apparatus for the single crystal is provided with at least a growing furnace in which the single crystal is grown, a drawing pivot, an annealing furnace in which the grown single crystal is stored and cooled, and a raw material supplier with which the raw material of the single crystal is supplied to a precious metal crucible. The growing furnace is provided with at least the precious metal crucible in which the raw material melt is stored, a refractory crucible which is arranged along outside of the precious metal crucible, and a growing furnace top cover which has a through-hole for the drawing pivot and is opened and shut freely. In a state that a bottom part of the annealing furnace comes into close contact with the upper part of the growing furnace top cover, the single crystal in the growing furnace is transferred to the annealing furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal manufacturing apparatus and a single crystal manufacturing method, and more particularly to a single crystal manufacturing apparatus having a growth furnace for growing a single crystal and an insulated furnace for cooling the grown single crystal. The present invention relates to a single crystal manufacturing method for growing a next single crystal while cooling the single crystal.

[0002]

2. Description of the Related Art Conventionally, lithium tantalate (LiTaO)
₃), Lithium niobate (LiNbO) ₃) Etc.
Since crystals have a relatively high melting point, platinum (Pt), platinum-b
Noble metal made of indium or iridium (Ir)
Use acupoints to create an atmosphere of an inert gas such as nitrogen or argon.
In an ambient atmosphere, production by the Czochralski method is one
Generally done.

FIG. 17 is a sectional view showing the structure of a conventional oxide single crystal manufacturing apparatus. The noble metal crucible 105 contains a melted single crystal raw material (raw material melt) 113, and the seed crystal 1 is removed from the surface of the raw material melt 113 under a predetermined temperature condition.
By pulling up the single crystal 117 below the seed crystal 116
Can be nurtured.

[0004] The grown single crystal 117 is supplied to the growing furnace 101.
In the process, so-called slow cooling, in which cooling is performed for a long time together with half of the raw material melt left in the crucible 105, is performed. Usually, cooling a single crystal requires one or more days. When one oxide single crystal is grown, about half of the raw material melt in the noble metal crucible 105 is consumed. The consumed single crystal raw material 113 is replenished with powdered sintering raw material, and preparation for the next single crystal growth is made. Further, since the noble metal crucible 105 made of iridium or the like is easily oxidized in a high temperature state, the crystal growth is generally performed by housing the growth furnace 101 in a SUS chamber 124.

[0005]

However, the single crystal 11
Since the cooling of 7 is performed in the growth furnace 101, the half of the raw material melt 113 left in the noble metal crucible 105 is simultaneously cooled and solidified. If the raw material melt 113 in the noble metal crucible 105 is solidified every time an oxide single crystal grows, the noble metal crucible 105 is deformed at an early stage, and the crucible must be frequently recast and remade. Further, if a heat cycle such as heating and cooling of the entire growth furnace 101 is repeatedly performed for each growth of the oxide single crystal, the refractory used as a heat insulating material in the growth furnace 101 easily causes heat shock cracking. As a result, the life of the refractory and the life of the growth furnace 101 are shortened. Therefore, the consumption rate of these device parts is increased, and as a result, the production cost of the single crystal is increased.

[0006] In addition, the oxide single crystal after growth is broken by thermal stress when a sudden temperature change is given (cracks are generated), so that cooling requires a long time. Also,
In order to cool the oxide single crystal in the growth furnace 101, start preparing for growing the next oxide single crystal until the cooling of one oxide single crystal is completed and taken out of the growth furnace 101. Can not. Therefore, only one or less oxide single crystal can be manufactured per day, which reduces the production efficiency of the apparatus and increases the unit cost of manufacturing the oxide single crystal.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a single crystal manufacturing apparatus and a single crystal manufacturing method capable of reducing the unit cost of single crystal production. It is to provide.

It is another object of the present invention to provide a single crystal manufacturing apparatus and a single crystal manufacturing method with high single crystal production efficiency.

Another object of the present invention is to provide a single crystal manufacturing apparatus and a single crystal manufacturing method capable of maintaining the life of the device parts for a long time.

Another object of the present invention is to provide a single crystal manufacturing apparatus and a single crystal manufacturing method capable of simultaneously cooling a single crystal and growing the next single crystal.

[0011]

Means for Solving the Problems In order to achieve the above object, a first feature of the present invention is to provide a growth furnace for growing a single crystal, a pulling shaft, and a single crystal containing the grown single crystal. The present invention is a single crystal manufacturing apparatus having at least a heat retaining furnace for cooling a crystal and a raw material supply device for supplying a single crystal raw material into a noble metal crucible. Here, the growth furnace includes at least a noble metal crucible containing a raw material melt, and a refractory crucible arranged along the outer periphery of the noble metal crucible. A seed crystal is arranged at the tip of the pulling shaft, and a single crystal is grown below the seed crystal by pulling the seed crystal from the liquid surface of the raw material melt. The insulated furnace can move with the pull axis in directions parallel and perpendicular to the pull axis. The raw material supply device has a function of adjusting the supply rate of the single crystal raw material.

A single crystal can be grown under the seed crystal by bringing the seed crystal into contact with the liquid surface of the raw material melt accommodated in the noble metal crucible and pulling up the pulling axis. The single crystal grown to a predetermined length is cut off from the liquid surface of the raw material melt. Then, the single crystal is moved from the growth furnace to the heat insulating furnace and stored in the heat insulating furnace.

According to the first feature of the present invention, since the single crystal is cooled in the insulated furnace, the raw material melt in the noble metal crucible is not solidified every time the single crystal is cooled, and the entire growth furnace is cooled. It is no longer necessary to repeat the heat cycle such as temperature rise and cooling for each single crystal growth. Therefore, early deformation of the noble metal crucible and early deterioration of the refractory contained in the growth furnace can be prevented.

Further, when cooling a single crystal in an insulated furnace,
By moving the insulated furnace along with the single crystal and the pulling axis in a direction perpendicular to the pulling axis, different pulling axes can be arranged in the growth furnace. Therefore, preparation for growing the next single crystal can be started while the single crystal is being cooled. As one of preparations for growing the next single crystal, in order to replenish the consumed single crystal raw material into the noble metal crucible, using a raw material supply device having a function of adjusting the supply rate of the single crystal raw material, What is necessary is just to supply the consumed single crystal raw material into the noble metal crucible.

[0015] In a first aspect of the present invention, the growing furnace comprises:
It is desirable to further include an openable and closable growth furnace upper lid having a hole through which the pulling shaft is provided, which is disposed on the refractory crucible. Further, it is desirable that the bottom of the heat retaining furnace can be brought into close contact with the upper part of the growth furnace upper lid. The single crystal is stored in the insulated furnace from the growth furnace while the bottom of the insulated furnace is in close contact with the upper part of the upper lid of the growth furnace. Store inside. Further, by closing the growth furnace upper lid during the growth of the single crystal, it is possible to prevent a falling object from above the growth furnace from entering the noble metal crucible and prevent the purity of the raw material melt from lowering. In addition, by closing the growth furnace upper lid even after storing the single crystal in the insulated furnace, falling objects in the noble metal crucible can be prevented as in the case of growing the single crystal.

It is desirable that the length in the pulling axis direction in the heat retaining furnace is substantially four times the length of the single crystal in the pulling axis direction. The length of the pulling axis direction in the insulated furnace is sufficiently longer than the length of the pulling axis direction of the single crystal, and from the upper end to the lower end of the single crystal when the center of the single crystal is arranged at the center of the insulated furnace. The temperature fluctuation range on the pulling axis in the region can be set to 50 ° C. or less.

It is desirable that the single crystal manufacturing apparatus further include a heat insulator surrounding the upper periphery of the growth furnace and the lower periphery of the heat insulation furnace, respectively. Temperature distribution on the pulling axis in the area where the single crystal is moved from the growth furnace to the heat retaining furnace when the temperature at the center of the heat retaining furnace is set to 0.7 to 1 times the melting point (absolute temperature) of the single crystal. Can be reduced monotonically from the growth furnace to the heat-retention furnace.

It is desirable that the apparatus for producing a single crystal further include a heat insulation furnace bottom cover for closing the bottom of the heat insulation furnace. By closing the bottom of the growth furnace containing the single crystal with the thermal insulation bottom lid, the whole single crystal can be cooled at a uniform rate without cooling the part near the bottom of the single crystal growth furnace first. it can. further,
It is desirable to arrange a powder of the same component as the single crystal at the top of the bottom lid of the insulated furnace. The single crystal stored in the insulated furnace lands on the insulated furnace bottom lid. By placing powder of the same component as the single crystal at the top of the insulated furnace bottom lid, a reaction between the high-temperature single crystal and the insulated furnace bottom lid is suppressed, and the cooled single crystal It is possible to prevent deterioration or cracks from occurring in the bottom portion.

It is desirable that the inner surface of the insulated furnace is covered with a heat-resistant, hardly deteriorating substance, so that the inner surface of the insulated furnace is unlikely to peel off during the pulling of the single crystal. The peeled inner surface of the insulated furnace can be prevented from falling into the noble metal crucible, and a decrease in the purity of the raw material melt can be avoided.

The second feature of the present invention is that (1) a single crystal raw material contained in a noble metal crucible disposed inside a growth furnace for growing a single crystal is melted to form a raw material melt. A first step, and (2) a second step of bringing a seed crystal disposed at the tip of the pulling shaft into contact with the liquid surface of the raw material melt,
(3) a third step of growing a single crystal below the seed crystal by pulling the pulling axis; and (4) a fourth step of separating the single crystal from the liquid surface after the single crystal reaches a predetermined length. Step, (5) a fifth step of moving the single crystal from the growth furnace to the insulated furnace at a predetermined speed and storing the single crystal in the insulated furnace, and (6) removing the single crystal, the pulling shaft, and the insulated furnace. A sixth step of moving in a direction perpendicular to the pulling axis synchronously;
(7) a seventh step of cooling the single crystal in the insulated furnace;
(8) An eighth step of replenishing the raw material of the single crystal in the noble metal crucible.

Here, the seventh step can be performed simultaneously with the eighth step. That is, the eighth step does not need to be performed after the completion of the cooling of the single crystal in the seventh step, and can be performed before or after the start of the cooling. Usually, cooling of a single crystal differs depending on its size, material, and the like, but may require about 10 hours. Eighth during cooling of the single crystal
When the supply of the step is completed, the process returns to the first step,
The supplied raw material may be melted again together with the raw material left after being pulled up to form a raw material melt. Furthermore, in the sixth step, since the pulling axis is moved in a direction perpendicular to the axis together with the single crystal, another pulling axis can be prepared after the first step, and the second and subsequent steps can be continuously performed.

In the third step, the apparatus is placed on a growth furnace,
It is desirable that the process be performed with the openable and closable growth furnace upper lid having a hole through which the pulling shaft penetrates closed, and further comprising a step of opening the growth furnace upper lid between the fourth step and the fifth step. Here, it is sufficient that the growth furnace top is in a closed state at least in the third step, and it is preferable that the top lid is also in the closed state in the first, second, and fourth steps.

In the fifth step, it is desirable that the distance from the bottom of the heat retaining furnace to the top of the growth furnace top is not more than 20 mm. More desirably, the bottom of the insulated furnace is in close contact with the top of the growth furnace top.

In the fifth step, the temperature of the center of the insulated furnace is set to a temperature of 0.7 to 1 times the melting point (absolute temperature) of the single crystal, and the temperature on the pulling shaft from the growing furnace to the insulated furnace is set. It is desirable that the predetermined speed in a region where the temperature is lower than the temperature at the center of the heat retaining furnace is higher than the predetermined speed in other regions.

In the fifth step, the speed is desirably 5 mm or less per minute until the vicinity of the center of the single crystal reaches a point where the temperature distribution in the pulling axial direction reaches a point near the center temperature of the insulated furnace.

In the five steps, it is desirable that the center of the single crystal accommodated in the heat insulating furnace is located above the center of the heat insulating furnace.

[0027] Between the fifth step and the seventh step, a step of mounting a bottom plate of a heat-retaining furnace in which powder of the same component as that of the single crystal is placed at the bottom of the heat-retaining furnace; Landing on the hearth lid. Here, these steps are performed in the fifth step.
It suffices if it is between the step and the seventh step, and it is preferably performed after the sixth step.

A third feature of the present invention is that a growing furnace for growing a single crystal, a pulling shaft, a heat-retaining furnace for storing the grown single crystal and cooling the single crystal, and a growing furnace. It is a single crystal production apparatus having at least a hermetic container for shielding from outside air and a gas inlet for introducing an inert gas into the hermetic container. The growth furnace includes at least a noble metal crucible containing a raw material melt. A seed crystal is arranged at the tip of the pulling shaft, and the single crystal is grown under the seed crystal by pulling the seed crystal from the liquid surface of the raw material melt. A hole through which the pulling shaft is formed is formed at an upper part of the insulated furnace, and the insulated furnace can move with the pulling shaft in directions parallel and perpendicular to the pulling shaft. The airtight container includes a growth furnace storage container surrounding the side and bottom surfaces of the growth furnace, and an airtight opening / closing lid that is in close contact with an upper portion of the growth furnace storage container and has a hole through which a pull-up shaft passes. The bottom of the insulated furnace can be in close contact with the top of the airtight opening / closing lid.

The hermetic container shields the growing furnace, which has a noble metal crucible relatively easily oxidized in a high temperature state, from the outside air. On the other hand, the insulated furnace and the single crystal housed in the insulated furnace are exposed to the atmosphere. By bringing the bottom of the insulated furnace into close contact with the upper part of the hermetic opening / closing lid, almost all the inert gas introduced into the hermetic container flows into the insulated furnace, and passes through the hole formed in the upper part of the insulated furnace. Released into the atmosphere.

According to the third feature of the present invention, the surroundings of the growth furnace having the noble metal crucible which is relatively easily oxidized in a high temperature state can be efficiently cut off from the outside atmosphere,
(1) The productivity is greatly improved by substantially improving the driving rate of the apparatus, and (2) the manufacturing cost can be reduced by extending the life of the noble metal crucible and the refractory member.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of the present invention will be described below with reference to the drawings. In the description of the drawings, parts similar to those of the related art are denoted by similar reference numerals. FIG. 1 is a cross-sectional view illustrating a configuration of a single crystal manufacturing apparatus according to the first embodiment of the present invention. The single crystal manufacturing apparatus includes a growth furnace 1 in which a single crystal 17 is grown, an insulated furnace 2 in which the grown single crystal 17 is accommodated and the single crystal 17 is gradually cooled, and a single crystal in which the seed crystal 16 is melted. A pulling shaft (14 to 16) for growing a single crystal 17 by pulling it from a liquid surface 26 of a crystal raw material (raw material melt) 13 is provided.

The growth furnace 1 includes a noble metal crucible 5 containing a raw material melt 13, a ring-shaped reflector 11 made of a noble metal disposed on the noble metal crucible 5, and a reflector 11. An after-heater 12 made of a noble metal, a refractory crucible 6 made of a heat-insulating material containing a refractory disposed on the outer periphery of the noble metal crucible 5, a heat-insulating tower 7 arranged on the refractory crucible 6, and a heat-insulating tower 7 And an openable and closable furnace top 8 having a hole 24 through which the pulling shafts (15, 16) pass. The growth furnace top lid 8 has a split structure, and the growth furnace top lid 8 can be opened and closed from outside the apparatus by moving the growth furnace top lid 8 left and right, respectively. The refractory crucible 6, the heat retention tower 7, and the growth furnace top lid 8
It is composed of thermal insulation. Precious metal crucible 5, reflector 1
1. On the outer periphery of the noble metal member such as the after heater 12,
An induction heating coil 10 is arranged at a predetermined distance from the refractory crucible 6. The induction heating coil 10 heats and raises the temperature of the noble metal members (5, 11, 12), and
The raw material of the single crystal in the furnace is melted, and the single crystal 1
7 to form a temperature distribution suitable for growing. The growing furnace 1 is supported by a column 18.

As the noble metal crucible 5, a crucible made of iridium (Ir) having a diameter of 180 mm and a height of 150 mm is used. Instead of iridium (Ir), platinum (Pt),
A platinum rhodium (Pt-Rb) alloy or the like may be used as a material. The raw material of the single crystal contained in the noble metal crucible 5 is made of a sintered material obtained by weighing and sintering powders of lithium carbonate (Li ₂ CO ₃ ) and tantalum oxide (Ta ₂ O ₅ ). The weight of the sintered material is 7 to 10 kg, and the total weight of the noble metal crucible 5 and the sintered material is 15 kg. In addition, lithium carbonate (Li ₂ CO ₃ ) and tantalum oxide (T
a ₂ O ₅ ) are distributed such that the composition ratio of lithium (Li) and tantalum (Ta) is Li / Ta = 0.943 (molar ratio).

The heat retaining furnace 2 is disposed above the growing furnace 1,
An opening for accommodating the single crystal 17 from the growth furnace is formed at the bottom thereof. The insulated furnace 2 pulls the single crystal 17, that is, a direction parallel to the pulling axis (14 to 16) (hereinafter referred to as “pulling axis direction”), and a direction perpendicular to the pulling axis (14 to 16). (Hereinafter referred to as a “pull-up axis perpendicular direction”). A lifting means 25 for moving the growing furnace 2 in the pulling axial direction is connected to the upper part of the growing furnace 2. By using the lifting means 25, the bottom of the heat retaining furnace 2 can be brought into close contact with the growth furnace top lid 8.

The material forming the heat insulating furnace 2 includes a heat insulating material and has a function of maintaining the temperature in the heat insulating furnace 2. Further, the heat retaining furnace 2 further has a heating means for forming a high temperature state necessary for storing the single crystal 17.
The inner surface of the heat-retaining furnace 2 is covered with a heat-resistant, hardly deteriorating substance, for example, a KM tube (Nikkato). Since the insulated furnace 2 is disposed above the growth furnace 1, the insulated furnace 2
The inner surface is prevented from peeling and mixing into the noble metal crucible 5, and the purity of the raw material melt 13 is prevented from lowering. Further, in order to form a wide region (uniform heat region) in which the temperature is uniform in the insulated furnace 2, the length of the furnace in the pulling axial direction is limited to the single crystal 17.
Is desirably at least three times the length of. In the first embodiment, since the length of the single crystal 17 is about 10 cm, the length of the insulated furnace 2 is set to 40 cm. When the temperature of the center of the heat-retaining furnace 2 is set to 1300 ° C. by using the heating means of the heat-retaining furnace 2, the temperature of the region 15 cm in the direction of the pulling axis from the center of the heat-retaining furnace 2 is in the range of 1300 ± 50 ° C. It was confirmed that a uniform soaking area was formed.

The pulling shaft is composed of the pulling rod 14 and the alumina rod 1
5 and a seed crystal 16. One end of the pulling rod 14 is connected to one end of the alumina rod 15. Alumina rod 15
Is connected to a seed crystal 16 at the other end. Lifting rod 14
, The alumina rod 15 and the seed crystal 16 are connected linearly. The other end of the pulling rod 14 is connected to a load cell 22 having a function of measuring the weight of the single crystal 17. The alumina rod 15 is provided in the heat insulating furnace 2 and the hole 24 in the growth furnace upper lid 8.
Through the seed crystal 16 disposed at the tip of the pulling shaft,
It can be brought into contact with the liquid surface 26 of the raw material melt 13 accommodated in the noble metal crucible 5.

The growth furnace 1, the heat insulation furnace 2, and the pulling shaft (14 to 1)
6) is disposed in a metal container (SUS chamber) 35. The inside of this container is a gas inlet 23
And is filled with an inert gas such as nitrogen or argon introduced from the furnace. Outside the metallic container, a raw material supply device 19 having a function of adjusting the supply speed of the raw material of the single crystal 17 and a weight sensor is arranged. A raw material supply pipe 20 is connected between the raw material supply device 19 and the growth furnace 1. The sintered material 21 can be supplied from the raw material supply device 19 to the noble metal crucible 5 in the growth furnace 1. The sintered material 21 in the raw material supply device 19 is a powder or a granular raw material.

A round plate-shaped or rectangular-shaped lid 4 is placed outside the metal container, and a heat-insulating furnace bottom cover 3 attached to the bottom of the heat-insulating furnace 2 is disposed on the lid 4. . The insulated furnace bottom lid 3 can be inserted into the metal container together with the lid 4. The insulated furnace bottom lid 3 has a built-in heating means and can control its own temperature.

Next, a method of manufacturing a single crystal using the single crystal manufacturing apparatus shown in FIG. 1 will be described with reference to FIGS. FIGS. 1 to 4 are cross-sectional views of the apparatus showing main manufacturing steps in a series of single crystal manufacturing steps from the growth of the single crystal 17 to the cooling of the grown single crystal 17.
FIG. 5 is a flowchart showing a method for manufacturing a single crystal.

(A) First, in step S01 shown in FIG. 5, the tip of the raw material supply pipe 20 is extended so as to come over the noble metal crucible 5, and the L
The sintering material 21 obtained by weighing and sintering the powders of i ₂ CO ₃ and Ta ₂ O ₅ is passed through a raw material supply pipe 20 to a noble metal crucible 5.
To supply. In addition, while rotating the noble metal crucible 5,
It is desirable to supply the sintering raw material 21. Precious metal crucible 5
It takes a certain amount of time until the sintering raw material 21 supplied to the sintering material is melted. If the sintering raw material 21 is continuously supplied without rotating, the sintering raw material 2
This is because 1 may accumulate and the sintering raw material 21 may not be melted smoothly.

(B) Next, in step S02, the power applied to the induction heating coil 10 is increased to heat the noble metal members (5, 11, 12) in the growth furnace 1. The sintering raw material is completely melted to form a raw material melt 13. And
By controlling the electric power applied to the induction heating coil 10, the temperature of the liquid surface 26 of the raw material melt 13 is adjusted to a temperature suitable for growing a single crystal. Further, by keeping the growth furnace top lid 8 closed, the temperature distribution in the growth furnace 1 is moderated, and a temperature distribution suitable for growing a single crystal is formed.

(C) Next, in step S 03, the pulling shafts (14 to 16) are moved toward the raw material melt 13, and the seed crystal 16 at the tip of the pulling shaft is moved to the liquid level 2 of the raw material melt 13.
6 is contacted. Next, in step S04, FIG.
As shown in (1), the single crystal 17 is grown under the seed crystal 16 by pulling up while rotating the pulling shafts (14 to 16) with the growth furnace top lid 8 closed.

(D) Next, in step S05, after the single crystal 17 has been grown to a predetermined length, the single crystal 17 is cut off from the liquid surface 26. The separation of the single crystal 17 is 10
The pulling shafts (14 to 16) may be pulled up to a predetermined distance at a high speed such as 100 mm / min. Also, a crystal tail is formed at the lower end of the single crystal 17 to form a liquid surface 26.
A method of separating more may be used.

(E) Next, preparations are made for moving the grown single crystal 17 from the growth furnace 1 to the heat retaining furnace 2. First, the temperature in the insulated furnace 2 is set to a predetermined temperature necessary for storing the single crystal 17 in a high temperature state immediately after being grown. That is, the temperature at the center of the heat retaining furnace 2 is set to a temperature of 0.7 Tm or more and less than Tm when the melting point of the single crystal 17 is represented by Tm in absolute temperature display. Here, the case where the temperature of the center of the heat retaining furnace 2 is set to 1300 ° C. will be described. In the first embodiment, the grown single crystal 1
Preparation for moving the furnace 7 from the growing furnace 1 to the insulated furnace 2 is performed after step S05, but is not limited to this, of course. Prior to step S05, it may be performed while growing the single crystal 17.

(F) Next, in step S06, the growth furnace upper lid 8 is opened right and left. Next, in step S07, as shown in FIG. 2, the single crystal 17 is moved from the growing furnace 1 to the insulated furnace 2 at a predetermined speed, and the single crystal 17 is stored in the insulated furnace 2. At this time, the bottom of the heat retaining furnace 2 is in close contact with the upper part of the growing furnace upper lid 8 in an open state. The movement of the single crystal is performed by pulling the pulling shafts (14 to 16) at a predetermined speed.

(G) Next, in step S08 shown in FIG. 6, the growth furnace top lid 8 is closed. Next, step S09
, The single crystal 17, the pulling shafts (14 to 16), and the heat retaining furnace 2 are synchronously moved (up) in the pulling axis direction. Next, in step S10, the thermal insulation furnace bottom cover 3 is attached to the bottom of the thermal insulation furnace 2 as shown in FIG. Specifically, the single crystal 17, the pulling shaft (14 to 16), and the insulated furnace 2 are moved (elevated) until the bottom of the insulated furnace 2 is located above the bottom lid 3 of the insulated furnace. The bottom lid 3 is moved in the vertical direction of the pulling axis together with the round plate-shaped lid 4, and is disposed below the heat insulating furnace 2. Then, the single crystal 17 and the pulling shaft (14 to
16) And, by lowering the insulated furnace 2, the insulated furnace bottom cover 3 is mounted on the bottom of the insulated furnace 2. Next, in step S11, the single crystal 17 is landed on the bottom lid 3 of the heat-retaining furnace.

(H) Next, in step S12, the single crystal 17, the pulling shafts (15, 16), and the heat retaining furnace 2 are moved in the vertical direction of the pulling shaft in synchronization. Specifically, first, the heat retaining furnace 2 and the lifting means 25 are separated, and the pulling rod 14 and the alumina rod 15 are separated. Then, an alumina rod 15, a seed crystal 16, a single crystal 17, an insulating furnace bottom cover 3,
The lid 4 and the insulated furnace 2 are synchronously moved in the vertical direction of the pulling axis and taken out of the metal container.

Next, in step S13, the single crystal 17 is cooled in the heat retaining furnace 2. Specifically, the temperature of the heat retaining furnace 2 is lowered to room temperature at a constant speed over about 10 hours. Then, after the cooling of the single crystal 17 is completed, the single crystal 17 is taken out of the heat retaining furnace 6 hours later.
Next, in step S14, it is determined whether to grow the next single crystal at the same time as step S13. When the next single crystal is grown (YE in step S14)
S), the process proceeds to step S15, in which the single crystal raw material (sintering raw material) 21 consumed by growing the single crystal 17 is supplied into the noble metal crucible 5. Since the weight of the raw material melt 13 consumed by growing the single crystal 17 is the weight of the single crystal 17 measured by the load cell 22, the sintering raw material 21 having the same weight as the single crystal 17 is supplied. . At this time, the sintering raw material 21 is supplied while rotating the noble metal crucible 5 (while rotating the support bar 18).

(G) Next, in step S16, as shown in FIG.
Then, the seed crystal 16 is mounted, and the next pulling shaft is prepared.
Then, the process returns to step S02, and returns to step S02.
To S13) are repeated. On the other hand, when the next single crystal growth is not performed (NO in step S14), the series of single crystal manufacturing methods ends.

FIG. 7A is a graph showing the temperature distribution on the pulling axis from the growing furnace 1 to the heat retaining furnace 2 in step S07. The vertical axis indicates the vertical distance from the liquid surface 26 of the raw material melt 13, and the horizontal axis indicates the temperature on the pulling axis. The temperature on the pulling shaft is set by opening the growth furnace top lid 8 and setting the core temperature to 1.
The measurement was performed using a thermocouple in a state where the growth furnace set at 300 ° C. was in close contact with the growth furnace top lid 8. FIG.
7B is a cross-sectional view illustrating a part of the single crystal manufacturing apparatus illustrated in FIG. 1 and illustrates a position of the single crystal 17 at a main temperature in a graph illustrated in FIG.

As shown in FIG. 7A, the temperature of the liquid surface 26 of the raw material melt 13 is about 1650 degrees, and the temperature on the pulling axis decreases with the vertical distance. The temperature falls below 1300 ° C. near the upper part of the heat retaining tower 7, forms a kink (minimum value) 27 of the temperature distribution near the bottom part of the growing furnace 2, and rises to 1300 ° C. at the center of the heat retaining furnace 2. In FIG. 7B, the single crystal 17A has a liquid level 26 at step S05.
Indicates a state in which it has been disconnected from. The single crystal 17B shows a state in which the center 29 of the single crystal 17 is arranged in a portion where the temperature on the pulling axis is 1300 ° C. near the upper end of the heat retaining tower 7.
The single crystal 17C is placed at the center of the heat insulating furnace 2 at the center 2 of the single crystal 17.
9 shows a state where it is arranged.

In the first embodiment of the present invention, the moving speed from the growing furnace 1 to the insulated furnace 2 in step S07 is such that the temperature on the pulling shaft is equal to the temperature at the center of the insulated furnace 2 (13).
00 ° C) and the other regions are different,
The region in the center of the insulated furnace 2 where the temperature is lower than the furnace temperature (1300 ° C.) is faster. That is, in FIG. 7B, the moving speed from the state of single crystal 17B to the state of single crystal 17C is faster than the moving speed from the state of single crystal 17A to the state of single crystal 17B. Specifically, the single crystal 17A
From the state of the single crystal 17B to the state of the single crystal 17B, and from the state of the single crystal 17B to the state of the single crystal 17C at a speed of 50 to 100 mm / min. In addition,
Although the movement time from the state of the single crystal 17A to the state of the single crystal 17B is set to 1 hour, it is preferable to move the single crystal 17 over a longer time from the viewpoint of reducing the thermal stress applied to the single crystal 17 and preventing cracks.

As described above, according to the first embodiment of the present invention, since the single crystal 17 is cooled in the insulated furnace 2, the raw material melt 13 in the noble metal crucible 5 It is not solidified each time it is cooled, and the temperature of the entire growth furnace 1 rises.
It is not necessary to repeat a heat cycle such as cooling every time the single crystal 17 is grown. Therefore, early deformation of the noble metal crucible 5 and early deterioration of the refractory contained in the growth furnace 1 can be prevented. Thus, it is possible to simultaneously improve the production capacity of the single crystal 17 and substantially reduce the production cost.

When cooling the single crystal 17 in the heat insulating furnace 2, the heat insulating furnace 2 is moved to the single crystal 17 and the pulling shaft (15, 1).
By moving the pulling shaft in the vertical direction with respect to the pulling shaft together with 6), different pulling shafts can be arranged in the growth furnace 1. Therefore, preparation for growing the next single crystal can be started while the single crystal 17 is being cooled. Therefore, continuous crystal pulling is at a practical level.
A single crystal manufactured at a rate of one crystal in two days can be manufactured at a rate of one crystal per day, and the production efficiency of the single crystal manufacturing apparatus is doubled as compared with the conventional one.

Further, the single crystal 17 is stored from the growing furnace 1 into the insulated furnace 2 while the bottom of the insulated furnace 2 is in close contact with the upper part of the growing furnace upper cover 8. The heat in the furnace can hardly escape from the gap. That is, the single crystal 17 is moved from the growth furnace 1 into the heat insulating furnace 2 without forming a local low-temperature portion near the gap between the growth furnace upper lid 8 and the heat insulating furnace 2 and without applying a large thermal stress to the single crystal 17. To store. Therefore, the incidence of single crystal cracking can be significantly reduced.

Further, by closing the growth furnace upper lid 8 during the growth of the single crystal 17, falling objects from above the growth furnace 1 are prevented from entering the noble metal crucible 5, and the raw material melt 1 is prevented.
3 can be prevented from lowering in purity. In addition, by closing the growth furnace upper lid 8 even after storing the single crystal 17 in the heat insulating furnace 2, falling objects into the noble metal crucible 5 can be prevented as in the case of growing the single crystal 17. .

Furthermore, by closing the growth furnace upper lid 8 when preparing the growth of the single crystal 17, the temperature distribution inside the growth furnace 1 is relaxed in the vertical direction, and the furnace is suitable for growing the single crystal 17. Environment can be formed. Moreover, since the growth furnace upper lid 8 has the hole 24 through which the pulling shafts (14 to 16) pass, the single crystal 17 can be grown by closing the growth furnace upper lid 8. Therefore, even when the single crystal 17 is grown, a furnace environment suitable for growing the single crystal 17 can be maintained, and the thermal stress applied to the single crystal 17 can be reduced.

(First Experimental Example) Next, an experimental example according to the first embodiment of the present invention will be described. First, in the first experimental example, when the single crystal 17 is moved from the growth furnace 1 to the insulated furnace 2, the distance from the bottom of the insulated furnace 2 to the upper part of the growth furnace top lid 8 is examined. In the embodiment, the case where the bottom of the heat retaining furnace 2 is in close contact with the upper part of the growth furnace upper lid 8, that is, the case where the distance from the bottom of the heat retaining furnace 2 to the upper part of the growth furnace upper lid 8 is 0 mm is shown. In the first experimental example, this distance (distance between the insulated furnace and the growth furnace) was set to 0, 10, 2
Under the four conditions of 0 and 40 mm, the heating furnace 2
The single crystal 17 was moved up to this point. Three single crystals 17 were grown for each condition, and the crack free ratio of the single crystal 17 after cooling and the crack free ratio after the poling step were measured. In this measurement, those deviating from the ideal state in the crystal pulling step were excluded from the crack-free rate count. Table 1 shows the measurement results.

[0059]

[Table 1] As shown in Table 1, the crack-free rate after cooling was 0,
Good results were obtained under the conditions of 10 and 20 mm.
Further, although the crack free ratio after the poling decreased under the condition of 20 mm, good results were obtained under the conditions of 0 and 10 mm. Therefore, in step S07 shown in FIG. 5, it was found that the generation of cracks can be prevented by setting the distance from the top of the growth furnace top lid 8 to the bottom of the heat retaining furnace 2 to 10 mm or less. Also, it was found that even when this distance was set to 20 mm or less, the effect of preventing cracks had already appeared.

FIG. 8A is a graph showing the temperature distribution on the pulling axis from the growing furnace 1 to the heat retaining furnace 2 in step S07, similarly to FIG. 7A. FIG. 8B is a cross-sectional view showing a part of the single crystal manufacturing apparatus, similarly to FIG. 7B, and shows the position of the single crystal 17 at the main temperature in the graph shown in FIG. I have. However, the growth furnace top lid 8
The distance from the top of the insulated furnace 2 to the bottom is not 0 mm,
That is, the temperature distribution is shown in a state where the upper part of the growth furnace top lid 8 and the bottom part of the heat retaining furnace 2 are not in close contact. As shown in FIG. 8A, a gap 28 is formed between the upper part of the growth furnace top lid 8 and the bottom part of the insulated furnace 2, so that heat in the furnace escapes from the gap 28, and Temperature will drop. On the other hand, the temperature of the liquid surface 26 of the raw material melt 13 and the center temperature of the insulated furnace 2 do not change from FIG. As a result, as shown in FIG. 8A, the kink 27 of the temperature distribution formed near the gap 28 between the upper part of the growth furnace top lid 8 and the bottom part of the heat retaining furnace 2 becomes large, and the single crystal 17 When passing through the kink 27 having the temperature distribution, a large thermal stress is applied, and there is a fear that cracks may occur.

(Second Experimental Example) Next, in a second experimental example, the moving speed of the single crystal 17 when the single crystal 17 is moved from the growth furnace 1 to the heat retaining furnace 2 will be examined. In the embodiment, in step S07, as shown in FIG. 7B, the moving speed from the state of single crystal 17A to the state of single crystal 17B is lower than the moving speed from single crystal 17B to single crystal 1B.
The moving speed up to the state of 7C was faster. As a result, the thermal stress applied to the single crystal 17 by the temperature distribution kink 27 could be reduced.

In the comparative example of the second experiment, the single crystal 17 was moved at a constant moving speed from a state in which the single crystal 17 was separated from the liquid surface 26 to a state in which the center 29 of the single crystal 17 was located at the center of the insulated furnace 2. The moving speed was 1.5 mm per minute, and the moving took about 300 minutes.

On the other hand, the moving speed of the single crystal according to the first embodiment is as follows. That is, the moving speed in the region (17A to 17B) in which the temperature on the pulling shaft is equal to or higher than the in-furnace temperature (1300 ° C.) at the center of the insulated furnace 2 is 1.
5 mm and moved over about 85 minutes. Then, the temperature on the pulling shaft is the furnace temperature (1300
C), the moving speed in the region (17B to 17C) is 100 mm / min. Ten single crystals 17 were grown for each, and the crack free ratio after cooling was examined. Table 2 shows the results.

[0064]

[Table 2] As shown in Table 2, when the single crystal 17 is slowly moved over time (moving speed is constant) according to the second experimental example, the crack-free ratio is 4/10, and the case according to the embodiment is performed. (Fast-forward after the temperature of the heat-retaining furnace), and the crack-free rate was 8/10. In other words, the probability that no crack would occur in the case of rapid traverse after the temperature of the insulated furnace was twice that in the case where the moving speed was constant. This consists of the heat insulation furnace 2 and the growth furnace top lid 8.
And a cooling portion having a low temperature (kink 27 of temperature distribution) is locally formed between them, and if this cooling portion is moved slowly, the temperature of single crystal 17 is affected by this cooling portion. . That is, it is considered that the temperature of the single crystal 17 sharply decreases, the internal stress of the single crystal 17 increases, and cracks easily occur.

On the other hand, as shown in the first embodiment,
The temperature on the pulling shaft is the temperature at the center of the insulated furnace 2 (1300
C)), by rapidly moving the region (17B to 17C) that is less than the local cooling portion, the influence of the local cooling portion on the temperature of the single crystal 17 is small, and the temperature is maintained while the temperature of the single crystal 17 is maintained at a somewhat high temperature. It can be stored in the furnace 2. Therefore, since the thermal stress applied to the single crystal 17 is small, it is considered that the probability of occurrence of cracks can be reduced.

In the second experimental example, in addition to a single crystal of lithium tantalate (LiTaO ₃ ), similar experiments were performed on lithium niobate (LiNbO ₃ ), and similar results were obtained.

(Third Experimental Example) FIGS. 7A and 7
(B) As shown in FIG.
Even when the bottoms of the pulleys are in close contact with each other, the kink 17 is formed in the temperature distribution on the pulling shaft in the close contact portion. As shown in the second experimental example, in order to reduce the thermal stress applied to the single crystal 17, the single crystal 17 is moved at high speed in the kink 27 having this temperature distribution. Therefore, in the third experimental example, the growth furnace 1
The device on the apparatus for making the temperature distribution on the pulling shaft up to the monotonously decreasing shape from the growing furnace 1 to the heat retaining furnace 2 without forming the kink 27 will be examined.

FIG. 9B is a sectional view showing a part (characteristic part) of the configuration of the single crystal apparatus according to the third experimental example.
As shown in FIG. 9B, the single crystal manufacturing apparatus according to the third experimental example has an outer periphery of the upper part of the heat retaining tower 7 and an outer periphery of the lower part of the heat retaining furnace 2 different from the apparatus shown in FIG. It further has a heat insulating material 30 surrounding each. Here, an alumina-based heat insulating material is used as the heat insulating material 30. FIG.
5 is a graph showing a temperature distribution on a pulling axis in the device configuration shown in FIG. As shown in FIG. 9 (a), by disposing the heat insulating material 30, the upper part of the growth furnace upper lid 8 and the heat insulating furnace 2
The temperature on the pulling shaft can be reduced monotonously from the liquid surface 26 of the raw material melt 13 to the center of the heat-retaining furnace 2 without forming a kink of the temperature distribution in a portion where the bottom portion is in close contact.

In the state shown in FIGS. 9A and 9B, ten single crystals 17 were grown and the crack-free ratio of the single crystal 17 after cooling was increased, as in the second experimental example. It was measured. The moving speed at this time was a constant speed of 2 mm per minute until the upper end of the single crystal 17 reached the vicinity of the bottom of the insulated furnace 2, and thereafter moved at a rapid feed rate of 100 mm per minute. Table 3 shows the measurement results.

[0070]

[Table 3] As shown in Table 3, by improving the temperature distribution, the crack-free rate after cooling increased to 9/10, and Table 2
It was found that the crack-free rate was improved as compared with 8/10 in the case of fast-forwarding after the temperature of the heat-retaining furnace.

The moving speed until the upper end of the single crystal 17 reaches the vicinity of the bottom of the insulated furnace 2 is set to 1, 3, 5, 7 per minute.
Under four conditions of mm, three single crystals were grown, respectively.
The crack-free rate after cooling was measured. Table 4 shows the measurement results.
Shown in

[0072]

[Table 4] As shown in Table 4, cracks did not occur under the conditions of 1 mm per minute and 3 mm per minute, and there were few cracks under the conditions of 5 mm per minute. However, under the condition of 7 mm / min or more, cracks were observed in all the single crystals 17. This is probably because the cooling rate of the single crystal 17 was increased, the thermal stress was increased, and cracks were more likely to occur.

(Fourth Experimental Example) Next, the handling of the single crystal 17 after being stored in the insulated furnace 2 will be described. As described in the embodiment, by setting the length in the pulling axis direction in the insulated furnace 2 to 40 cm, which is three times or more the length of the single crystal 17 (about 10 cm), the temperature in the insulated furnace 2 is increased. Can uniformly form a wide area (heat uniforming area). Therefore, by storing the single crystal 17 in the heat retaining furnace 2 so that the center of the single crystal 17 and the center of the heat retaining furnace coincide with each other, the entire single crystal 17 can be uniformly cooled.

However, when the length of the insulated furnace 2 cannot be made sufficiently long, the following problems occur. That is, from the time when the single crystal 17 is stored in the insulated furnace 2 in step S07 to the time when the insulated furnace bottom cover 3 is attached to the bottom of the insulated furnace in step S10, the single crystal 17 is in a state where the bottom is open Is stored in the heat retaining furnace 2. In addition, in step S09, the heat retaining furnace 2 is moved (elevated) in a direction parallel to the pulling axis, and its bottom is released from the upper part of the growth furnace upper lid 8. Therefore, step S07
From Step S10 to Step S10, the temperature distribution in the insulated furnace 2 has a shape in which the temperature near the bottom is lowered, and the single crystal 17
There is a concern that the lower end side is cooled first and cracks occur.

FIG. 10A is a graph showing the temperature distribution on the pulling axis when the bottom of the heat retaining furnace 2 is open. FIG. 10B is a cross-sectional view showing the growth furnace 2 with the bottom opened and the single crystal 17 stored in the growth furnace 2. As shown in FIG. 10A, when the length in the pulling axis direction in the heat retaining furnace 2 cannot be made sufficiently long, it is understood that the temperature near the bottom is low when the bottom is open. In the temperature distribution shown in FIG.
Is arranged such that the center 29 and the center 34 of the insulated furnace 2 coincide with each other, the temperature difference between the upper end 31 and the lower end 32 of the single crystal 17 increases, and the lower end 32 side of the single crystal 17 is cooled first, Cracks may occur.

Therefore, as shown in FIG. 10B, the single crystal 17 is housed in the growth furnace 2 such that the center 29 of the single crystal 17 is located above the center 34 of the heat retaining furnace 2. Alternatively, the single crystal 17 is housed in the growth furnace 2 such that the distance between the bottom of the heat insulating furnace 2 and the lower end of the single crystal 17 is about the inner diameter of the heat insulating furnace 2 or more. Thereby, the temperature difference between the upper end 31 and the lower end 32 of the single crystal 17 can be kept small, the single crystal 17 is placed in a uniform temperature environment, and the occurrence of cracks can be suppressed.

(Fifth Experimental Example) Next, the material of the uppermost part of the thermal insulation furnace bottom cover 3 will be examined. Generally, an oxide single crystal is
Under high temperature conditions, it tends to react with substances of different materials. In particular, this tendency is strong in oxide single crystals containing lithium (Li), and at least LiTaO ₃ ,
It has been confirmed that a single crystal of LiNbO ₃ reacts with alumina in a high temperature state.

More specifically, high-purity alumina wool was placed on the top of the heat retaining furnace bottom cover 3, and the single crystal 17 was landed on the heat retaining furnace bottom cover 3 and cooled in step S11.
After cooling, white fogging or cracking sometimes occurred at the lower portion of the single crystal 17 which was in contact with the heat retaining furnace bottom lid 3.

Then, with the powder of the same component as that of the single crystal placed on the platinum foil at the uppermost part of the heat retaining furnace bottom cover 3, the single crystal 17 was landed on the heat retaining furnace bottom cover 3 and cooled. After cooling, no trace of the reaction was observed at the lower portion of the single crystal 17 which was in contact with the heat retaining furnace bottom cover 3, and no crack was generated.
As is evident from the above, it is desirable to use a material having the same component as the single crystal 17 in the portion of the apparatus that is in contact with the single crystal 17 in the high temperature state. Also, a sufficient effect can be expected even if only a material such as platinum foil, which is clearly not reacting with the single crystal 17, is arranged on the uppermost portion of the heat retaining furnace bottom cover 3.

In the first embodiment of the present invention, only LiTaO ₃ and LiNbO ₃ are referred to as oxide single crystals, but other single crystals of oxide such as langasite-type compounds may be used. On the other hand, the effects described above can be sufficiently expected. Further, the present invention is not limited only to the oxide single crystal. This invention is also effective for other single crystals that are easily cracked and require a long time for cooling, and similar effects such as improvement in production efficiency, reduction in manufacturing cost, and long life of equipment parts can be expected. .

(Second Embodiment) In the first embodiment, in order to prevent oxidation of a member made of a noble metal such as the noble metal crucible 5, the reflector 11, or the after heater 12, only the growth furnace 1 is used. The heat insulating furnace 2 is also housed in an airtight SUS chamber 35, and the noble metal member (5, 1
1 and 12) have been described in which the crystal is pulled without touching the atmosphere.

However, since the grown single crystal 17 is an oxide single crystal, no major problem occurs even if it is exposed to the atmosphere. If the insulated furnace 2 also has a structure that does not itself contain a substance that is easily oxidized, no major problem occurs even if it is exposed to the air atmosphere. Therefore, the grown single crystal 1
Strict airtightness is not required for 7 and insulated furnace 2. Only the growth furnace 1 having a noble metal member such as a noble metal crucible 5 that is easily oxidized in a high temperature state requires airtightness.

Therefore, in the second embodiment of the present invention,
A single crystal manufacturing apparatus capable of continuously pulling a crystal with a relatively simple structure by blocking the growth furnace from the outside air and disposing the growth furnace in the atmosphere will be described.

FIG. 11 is a sectional view showing a structure of a single crystal manufacturing apparatus according to the second embodiment of the present invention. The single crystal manufacturing apparatus according to the second embodiment includes a growth furnace 51 for growing a single crystal, a pulling shaft (14 to 16), and cooling of the single crystal 17 by housing the grown single crystal 17. Is carried out, an airtight container for shutting off the growth furnace 51 from the outside air, and a gas inlet 73 for introducing an inert gas into the airtight container.

The growth furnace 51 has at least a noble metal crucible 5 in which the raw material melt 13 is stored. Precious metal crucible 5
Is made of a noble metal such as iridium, platinum and platinum rhodium which is easily oxidized at a high temperature. Here, an iridium crucible having a diameter of 180 mmφ and a height of 150 mm is used. The growth furnace 51 is provided with a reflection plate 11 made of a noble metal.
And an after-heater 12, a refractory crucible 6, a refractory heat-insulating tower 7, a refractory ring 61 disposed on the refractory heat-insulating tower 7, and a growth furnace top 58 disposed on the refractory ring 61. And further comprising: The refractory ring 61 is made of a heat insulating material containing a refractory, like the refractory crucible 6 or the refractory heat retaining tower 7. The growth furnace upper lid 58 has a hole through which the pulling shaft 15 can penetrate, and has a structure that can be opened and closed so that the grown single crystal 17 can pass through.
The structure of the breeding furnace top lid 58 will be described later with reference to each drawing in FIG. An induction heating coil 10 is arranged on the outer periphery of the noble metal member (5, 11, 12).

The pulling shafts (14 to 16) are
, An alumina rod 15 and a seed crystal 16. A seed crystal 16 is arranged at one end of the pulling shaft.
By pulling up from the liquid surface of No. 3, the single crystal 1
7 are raised. A load cell 22 is connected to the other end of the pulling shaft.

The heat retaining furnace 52 is disposed above the growth furnace 51, and has an opening formed at the bottom for receiving the single crystal 17 from the growth furnace 51. The heat retaining furnace 52 can move in the pulling axis direction and the pulling axis vertical direction. A hole through which the alumina rod 15 can penetrate is formed in the upper part of the heat retaining furnace 52. The heat retaining furnace 52 can move in synchronization with the pulling shaft. Above the hole of the heat-retaining furnace 52, a heat-retaining furnace upper lid 60 which is in close contact with the hole and has a thin tube capable of penetrating the pulling shaft (alumina rod) 15 is arranged. The diameter of the thin tube is small enough to allow the alumina rod 15 to penetrate it, and is smaller than the diameter of the hole of the heat retaining furnace 52.

The airtight container includes a growth furnace storage container (54, 55) surrounding the side and bottom surfaces of the growth furnace 51, and an airtight opening / closing lid 59, which is in close contact with the upper part of the growth furnace storage container 54 via a quartz ring 57. At least. The hermetic opening / closing lid 59 has a hole 74 through which the pulling shaft 15 can pass, and has a structure that can be opened and closed so that the grown single crystal 17 can pass through. The structure of the airtight opening / closing lid 59 will be described later with reference to each drawing in FIG. In the second embodiment, the growth furnace storage container includes a cylindrical growth furnace storage cylinder 54 disposed on the outer periphery of the growth furnace 51, and a growth furnace 5.
1 and a base 55 closely attached to a lower portion of the growth furnace storage cylinder 54. The growth furnace storage cylinder 54 is made of quartz. The base 55 is made of refractory or water-cooled SUS (stainless steel). The induction heating coil 10 is arranged on the outer periphery of the growth furnace storage cylinder 54. The upper surface of the hermetic opening / closing lid 59 is a flat surface, and the bottom of the heat insulating furnace 52 is in close contact with the upper portion of the hermetic opening / closing lid 59. Of course, the bottom of the heat retaining furnace 52 also has a flat structure in order to ensure close contact with the upper surface of the airtight opening / closing lid 59.

The gas inlet 73 is arranged in a part of the growth furnace housing cylinder 54. The gas introduced from the gas inlet 73 is an inert gas such as argon, nitrogen, and krypton.

As described above, the lower part of the growth furnace housing cylinder 54 is in close contact with the base 55, and the airtight opening / closing lid 59 is in close contact with the upper part of the growth furnace housing cylinder 54 via the quartz ring 57. The bottom of the heat insulating furnace 52 is in close contact with the upper part of the airtight opening / closing lid 59. Therefore, the inert gas introduced from the gas inlet 73 is introduced into the hermetic container including the inside of the growth furnace 51, introduced into the insulated furnace 52 through the hole 74 of the hermetic opening / closing lid 59, Is released to the atmosphere from the gap between the alumina rod 15 and the alumina. The inside of the airtight container, the airtight opening / closing lid 59 and the heat insulation furnace 52 is provided with a gas inlet 73.
Except for the gap between the heat-retaining furnace upper lid 60 and the alumina rod 15, the air-tight state is maintained. Only an inert gas is introduced from the gas inlet 73. On the other hand, since the inert gas is discharged from the gap between the furnace upper cover 60 and the alumina rod 15, it is possible to almost prevent the outside air from entering through the gap. Therefore, the inside of the growth furnace 51 can be isolated from the atmosphere. In other words, the gas inlet 73
, The internal pressure of the airtight container, the airtight opening / closing lid 59 and the heat retaining furnace 52 is kept higher than the atmospheric pressure, and the heat retaining furnace upper lid 60 and the alumina rod 15
Can be prevented from flowing into the air from the gap between the air and the air.

FIG. 15 is a plan view showing the structure of the growth furnace top lid 58, and shows the growth furnace top lid 58 as viewed from the pulling-up axis direction.
2 shows a planar shape. FIG. 15A shows a state in which the growth furnace upper cover 58 is closed, and FIG.
8 shows the open state. As shown in FIG. 15A, the growth furnace upper lid 58 has a pair of openable and closable blades 58b slidable in a direction perpendicular to the pulling axis, and a predetermined direction in a direction perpendicular to the sliding direction of the openable and closable blade 58b. A pair of fixed blades 58a spaced apart. The growth furnace top lid 58 plays a role in creating a furnace temperature environment suitable for crystal growth. 4 blades (5
8a, 58b) are arranged on the refractory ring 61.

An arcuate fixed blade 58 a arranged along the inner periphery of the growth furnace housing cylinder 54 is in close contact with the refractory ring 61. The openable and closable blade 58b disposed between the pair of fixed blades 58a is a refractory ring 6.
1 (a circle shown by a dotted line in FIG. 15A). A hole 58c is formed in the center of the mating portion of the pair of openable / closable blades 58b so that the alumina rod 15 can penetrate therethrough. The openable and closable blade 58b has a semicircular cut at a substantially central portion of the straight portions facing each other. The semi-circular cut forms a circular hole 58c through which the alumina rod 15 passes through the center of the growth furnace upper lid 58 when the growth furnace upper lid 58 is closed and the two openable blades 58b are combined. Become.

As shown in FIG. 15B, by sliding a pair of openable / closable blades 58b right and left on the refractory ring 61, the inner periphery of the refractory ring 61 (FIG.
A circle shown by a solid line in FIG. The opening of the refractory ring 61 has such a size that the grown single crystal can pass through.

FIG. 16 is a plan view showing the structure of the hermetic opening / closing lid 59, and shows the plan shape of the hermetic opening / closing lid 59 when viewed from the pulling-up axis direction. FIG. 16A shows a state in which the airtight opening / closing lid 59 is closed, and FIG. 16B shows a state in which the airtight opening / closing lid 59 is open. As shown in FIG. 16A, the airtight opening / closing lid 59 includes a pair of openable / closable blades 59b slidable in a direction perpendicular to the pulling-up axis, similarly to the growth furnace upper lid 58, and a pair of openable / closable blades 59b. It has a pair of fixed blades 59a arranged at predetermined intervals in a direction perpendicular to the sliding direction. The four blades (59a, 59b) are arranged on the quartz ring 57.

The arc-shaped fixed blade 59a is in close contact with the quartz ring 57. A pair of fixed blades 5
An openable / closable blade 59b disposed between the nozzles 9a covers the inner periphery of the quartz ring 57 (a circle shown by a dotted line in FIG. 16A). A hole 59c is formed in the center of the joint of the pair of openable / closable blades 59b so that the alumina rod 15 can pass therethrough. Retractable blade 59b
Has a semicircular cut in the approximate center of the straight portions facing each other. The semicircular cut forms a circular hole 59c in the center of the airtight opening / closing lid 59 through which the alumina bar 15 passes when the airtight opening / closing lid 59 is closed and the two opening / closing blades 59b are combined. Will be.

As shown in FIG. 16B, by sliding a pair of openable / closable blades 59b right and left on the quartz ring 57, the inner periphery of the quartz ring 57 (FIG.
A circle shown by a solid line in FIG. The opening of the quartz ring 57 has such a size that the grown single crystal can pass through.

(Single Crystal Manufacturing Method) Next, a single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. 11 will be described with reference to FIGS. 11 to 14
FIG. 4 is an apparatus cross-sectional view showing main manufacturing steps in a series of single crystal manufacturing steps from the growth of the single crystal 17 to the cooling of the grown single crystal 17.

(A) First, the composition ratio is Li / Ta = 0.9.
Li (molar ratio) ₂CO₃And Ta₂
O₅Sintering material weighing 10 kg and weighing 10 kg
The material is supplied into the noble metal crucible 5. Induction heating coil 1
Noble metal members in the growth furnace 1 by increasing the power applied to
(5,11,12) is heated and the weight is 15kg
A melt 13 is formed. Then, the heat is applied to the induction heating coil 10.
Control the electric power of the raw material melt 13
Adjust to a temperature suitable for crystal growth.

The step of melting the sintered material to form the raw material melt 13 and adjusting the temperature to a temperature suitable for growing a single crystal is referred to as a “furnace heating step”. In the furnace temperature raising step, the growth furnace upper lid 58 shown in FIG. 15 and the hermetic opening / closing lid 59 shown in FIG. 16 are in a closed state. The temperature distribution in the growth furnace 51 is moderated to form a temperature distribution suitable for growing a single crystal. Further, the bottom of the heat insulating furnace 52 is in close contact with the upper part of the airtight opening / closing lid 59, and an inert gas is continuously introduced from the gas inlet 73.

(B) Next, the pulling shaft (14 to 16) is moved toward the raw material melt 13, and the seed crystal 1 at the tip of the pulling shaft is moved.
6 is brought into contact with the liquid surface of the raw material melt 13. As shown in FIG. 11, the single crystal 17 is grown under the seed crystal 16 by pulling while rotating the pulling shafts (14 to 16). After the single crystal 17 has been grown to a predetermined length, the single crystal 17 is cut off from the liquid surface. Separation of the single crystal 17 is performed at 10 to 1
The pulling shafts (14 to 16) may be pulled up to a predetermined distance at a high speed such as 00 mm / min. Alternatively, a method of forming a crystal tail at the lower end of the single crystal 17 and separating from the liquid surface may be used. In this way, a lithium tantalate (LiTaO ₃ ) single crystal 17 having a straight copper diameter of 105 to 110 mmφ and a weight of 6 to 7 kg is grown.

The process from the contact of the seed crystal 16 to the liquid surface to the separation of the single crystal 17 from the liquid surface is referred to as a “single crystal growing process”. Also in the single crystal growing step, the growing furnace upper lid 58 and the airtight opening / closing lid 59 are in a closed state. Further, the bottom of the heat insulating furnace 52 is in close contact with the upper part of the airtight opening / closing lid 59, and an inert gas is continuously introduced from the gas inlet 73.

(C) Next, as shown in FIG. 12, preparations are made for moving the grown single crystal 17 from the growth furnace 51 to the insulated furnace 52. First, the temperature in the heat-retaining furnace 52 is set to a predetermined temperature necessary for storing the single crystal 17 in a high-temperature state immediately after being grown. In the second embodiment as well, preparation for moving the grown single crystal 17 from the growth furnace 51 to the insulated furnace 52 is performed after the single crystal growth step. It may be performed during the operation. Next, the openable / closable blade 58b of the growth furnace upper cover 58 shown in FIG.
Open the openable blade 59b of the airtight opening / closing lid 59 shown in FIG.

(D) Next, the single crystal 17 is moved at a predetermined speed from the growing furnace 51 to the insulated furnace 52, and the single crystal 17 is stored in the insulated furnace 2. Then, the opening / closing blade 58b of the growth furnace upper lid 58 is closed, and the opening / closing blade 59b of the airtight opening / closing lid 59 is closed. The process from the preparation process for moving the single crystal 17 to the storage of the single crystal 17 in the heat insulating furnace 52 and closing of the lids (58, 59) is referred to as “crystal heat insulating furnace storage process”. In the process of storing the crystal insulated furnace,
The bottom of the heat-retaining furnace 52 is in close contact with the top of the airtight opening / closing lid 59, and an inert gas is continuously introduced from the gas inlet 73.

In the second embodiment, the distance between the growth furnace upper lid 58 and the hermetic opening / closing lid 59 in the direction of the pulling axis is made as short as possible in consideration of the step of storing the crystal in the heat insulating furnace. When the single crystal 17 passes through the growth furnace upper lid 58 and the airtight opening / closing lid 59, the four surfaces are made of four blades (58 a, 58 b) made of refractory material of the growth furnace upper lid 58 and the quartz made by the airtight opening / closing lid 59. 4 blades (59a, 5
9b), the bottom of the heat-retaining furnace 52 is in close contact with the top of the airtight opening / closing lid 59. Therefore, there is almost no place for heat to escape in the vertical direction of the pulling axis. for that reason,
The single crystal 17 is stored in the heat retaining furnace 52 without being cooled.

(E) Next, the single crystal 17 and the pulling shaft (14
16), and the heat retaining furnace 52 is moved (elevated) in the pulling axis direction in synchronization. Then, as shown in FIG. 13, a heat insulation furnace bottom cover 53 is attached to the bottom of the heat insulation furnace 52. At this time,
The flow rate of the inert gas introduced from the gas inlet 73 is increased to prevent the air from entering the airtight container through the hole 59c of the airtight opening / closing lid 59. Specifically, until the bottom of the insulated furnace 52 is higher than the insulated furnace bottom lid 53, the single crystal 17,
After moving (raising) the pulling shafts (14 to 16) and the heat retaining furnace 52, the heat retaining furnace bottom cover 53 is moved in the vertical direction of the pulling axis and attached to the bottom of the heat retaining furnace 52. After that, the heating furnace 52
And the insulated furnace bottom cover 53. Then, the single crystal 17 is landed on the thermal insulation furnace bottom cover 53, and the alumina rod 15 is separated from the pulling rod. Single crystal 17, pulling shaft (15, 1
6) The insulated furnace 52 and the insulated furnace bottom cover 53 are moved in the vertical direction of the pulling axis. At the same time, the power to the induction heating coil 10 is increased, and the temperature of the noble metal crucible 5 is increased. In order to prevent the air from entering the airtight container from the hole 59c of the airtight opening / closing lid 59, the hole 59c of the airtight opening / closing lid 59 is provided with heat resistance and heat shock resistance immediately after the movement (up) of the insulated furnace 52. A lid may be used with a certain plate shape.
It takes about one day (24 hours) or more time to cool the single crystal 17 after the pulling.

(F) Next, the single crystal 1
At the same time as the cooling of 7, a single crystal raw material (sintering raw material) 21 consumed by growing the single crystal 17 is supplied into the noble metal crucible 5. The raw material supply device has a raw material supply container 69 for storing the sintering raw material 21 and a raw material supply pipe 70 that can be arranged at the center of the noble metal crucible 5 so as to be substantially parallel to the pulling axis direction. One end of the raw material supply pipe 70 is connected to the raw material melt 13.
The raw material supply pipe 70 penetrates through the hole 58c of the upper lid 58 of the growing furnace and the hole 59c of the airtight opening / closing lid 59 in a closed state. From the other end, the sintering raw material 21 is supplied into the crucible 5 at a predetermined supply speed.

The weight of the raw material melt 13 consumed by the growth of the single crystal 17 is determined by the single crystal 1 measured by the load cell.
Since the weight is 7, the sintering raw material 21 having the same weight as the single crystal 17 is supplied. Then, a raw material melt 13 having a total weight of 15 kg is formed. At this time, the sintering raw material 21 is supplied while rotating the noble metal crucible 5 (while rotating the support bar). Since the heat retaining furnace 52 can be moved in the pulling axis (vertical) direction and the pulling axis vertical (left / right) direction, the workability is very good. Further, since the raw material supply pipe 70 is disposed in the pulling shaft (vertical) direction, the sintering raw material 21 is not clogged in the middle of the raw material supply pipe 70 as compared with the case shown in FIG.

(G) Next, as shown in FIG. 14, the bottom of the new heat-retaining furnace 52b to which the heat-retaining furnace upper lid 60 is attached is brought into close contact with the upper part of the airtight opening / closing lid 59. The alumina rod 15 and the seed crystal 16 are placed in the narrow tube of the heat-retaining furnace upper cover 60, the closed airtight opening / closing cover 59 and the holes (58 c, 59) of the growing furnace upper cover 58.
After passing through c), the tip of the seed crystal 16 extends to the liquid surface of the raw material melt 13, and the next crystal is grown. Oxide single crystals are generally easily broken, and cooling after pulling requires about 10 hours or more. However, most of the long-term cooling is performed by the insulated furnace 52a placed outside the hermetic container.
Within. Removal of insulated furnace 52a and new insulated furnace 5
2b, attachment and removal of the raw material supply pipe 70,
The workability of resetting the seed crystal 16 is very good because there is no spatial restriction.

By repeatedly performing the above procedure,
Although ten crystals were pulled continuously, all of the single crystals did not suffer from defects such as cracks and the like.
No tube clogging occurred. Furthermore, deterioration of the refractory in the growth furnace was hardly observed.

As described above, according to the second embodiment of the present invention, the description of “Improvement and production of equipment by extending the life of refractory and precious metal members” described in the first embodiment. In addition to the operation and effect relating to “cost reduction”, the following other operation and effect can be achieved. (1) Since only the growth furnace 51 is housed in the airtight container, the airtight container itself can be made smaller.

(2) In the “furnace heating step”, “single crystal growing step” and “crystal storage furnace storing step”, no outside air enters the growing furnace 51 in a high temperature state. The oxidation of the noble metal member disposed in the growth furnace 51 can be prevented.

(3) It is not necessary to replace the insulated furnace 52a for accommodating the single crystal 17 to be gradually cooled and the empty insulated furnace 52b for accommodating the next single crystal inside the hermetic chamber, which is realized. The driving device (such as the lifting means 25) is not required.

(4) Because the sintering raw material 21 is not supplied from outside the large airtight chamber (see FIG. 4), the sintering raw material 21 is supplied by using the raw material supply pipe 70 which is vertically arranged right above the noble metal crucible 5. In addition, the distance between the raw material supply container 69 and the noble metal crucible 5 does not increase, and the sintering raw material 21 does not clog in the middle of the tube 70.

As described above, the present invention has been described with reference to the first and second embodiments and the first to fifth experimental examples. However, the description and drawings constituting a part of this disclosure explain the present invention. It is not to be understood as limiting. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.

In the embodiment, lithium tantalate (LiTaO ₃ ), which is a typical oxide single crystal, has been described. However, lithium niobate (LiNbO ₃ ) or other broadly defined compounds such as langasite-type compounds are used. Similar effects are expected for oxide single crystals. Further, the present invention is not limited to the oxide single crystal, and since a noble metal member such as a crucible disposed in a manufacturing apparatus to be used is easily oxidized at a high temperature or a crack is easily generated in a pulled crystal, a long time is required for cooling. Even for other single crystals that require time (for example, about 24 hours), it is possible to improve the substantial driving rate of an apparatus for manufacturing the single crystal.

[0116]

As described above, according to the present invention, it is possible to provide a single crystal manufacturing apparatus and a single crystal manufacturing method which can keep the unit cost of single crystal low.

Further, according to the present invention, it is possible to provide a single crystal manufacturing apparatus and a single crystal manufacturing method with high single crystal production efficiency.

Further, according to the present invention, it is possible to provide a single crystal manufacturing apparatus and a single crystal manufacturing method capable of maintaining a long life of the device parts.

Further, according to the present invention, it is possible to provide a single crystal manufacturing apparatus and a single crystal manufacturing method capable of simultaneously cooling a single crystal and growing the next single crystal.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a single crystal manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view showing main manufacturing steps in a single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. 1 (part 1).

FIG. 3 is a cross-sectional view showing main manufacturing steps in a single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. 1 (part 2).

FIG. 4 is a sectional view showing main manufacturing steps in a single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. 1 (part 3).

FIG. 5 is a flowchart illustrating a single crystal manufacturing method using the single crystal manufacturing apparatus illustrated in FIG. 1 (part 1).

FIG. 6 is a flowchart illustrating a single crystal manufacturing method using the single crystal manufacturing apparatus illustrated in FIG. 1 (part 2).

FIG. 7A is a graph showing a temperature distribution on a pulling axis from a growing furnace to a heat-retaining furnace in step S07 shown in FIG. 5; FIG. 7B is a cross-sectional view showing a part of the single crystal manufacturing apparatus shown in FIG. 1, and shows the position of the single crystal at the main temperature in the graph shown in FIG. 7A.

FIG. 8 (a) shows the temperature on the pulling shaft from the growing furnace to the insulated furnace when the bottom of the insulated furnace and the top of the growing furnace lid are not in close contact with each other according to the first experimental example. It is a graph which shows distribution. FIG. 8B is a cross-sectional view showing a part of the single crystal manufacturing apparatus shown in FIG. 1, and shows the position of the single crystal at the main temperature in the graph shown in FIG.

FIG. 9A is a graph showing a temperature distribution on a pulling axis from a growing furnace to a heat-retaining furnace according to a third experimental example. FIG. 9B is a cross-sectional view showing a part of the single crystal manufacturing apparatus shown in FIG. 1, and shows the position of the single crystal at the main temperature in the graph shown in FIG. 9A.

FIG. 10 (a) is a graph showing a temperature distribution on a pulling axis in a state where the bottom of an insulated furnace is open according to a fourth experimental example. FIG. 10 (b) is a cross-sectional view showing the growth furnace with the bottom open and the single crystal stored in the growth furnace.

FIG. 11 is a cross-sectional view illustrating a configuration of a single crystal manufacturing apparatus according to a second embodiment of the present invention.

12 is a cross-sectional view illustrating main manufacturing steps in a single crystal manufacturing method using the single crystal manufacturing apparatus illustrated in FIG. 11 (part 1).

13 is a cross-sectional view showing main manufacturing steps in a single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. 11 (part 2).

FIG. 14 is a sectional view showing main manufacturing steps in a single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. 11 (part 3).

15 is a plan view showing the configuration of the growth furnace upper lid shown in FIG. 11, wherein FIG. 15 (a) shows a state where the growth furnace upper lid is closed, and FIG. 15 (b) shows a state where the growth furnace upper lid is opened. Is shown.

16 is a plan view showing the configuration of the hermetic opening / closing lid shown in FIG. 11; FIG. 16 (a) shows a state in which the hermetic opening / closing lid is closed; FIG. Indicates an open state.

FIG. 17 is a cross-sectional view showing a configuration of a single crystal manufacturing apparatus according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 51 Growth furnace 2, 52 Heat insulation furnace 3, 53 Heat insulation furnace bottom cover 4 Lid 5 Precious metal crucible 6 Refractory crucible 7 Heat insulation tower 8, 58 Growth furnace top lid 10 Induction heating coil 11 Reflector plate 12 After heater 14 Pulling rod 15 Alumina Rod 16 Seed crystal 17, 17A, 17B, 17C Single crystal 18 Prop 19 Raw material supply device 20, 70 Raw material supply pipe 21 Sintered raw material 23, 73 Gas inlet 24, 58c, 59c Hole 25 Lifting means 26 Liquid level 27 Temperature distribution Kink 28 Gap 29 Center 30 Insulation material 54 Growth furnace storage cylinder 55 Base 57 Quartz ring 59 Airtight opening / closing lid 60 Thermal insulation furnace top lid 61 Refractory ring 69 Raw material supply container

Claims (22)

[Claims] A precious metal crucible containing a raw material melt;
A growth furnace for growing a single crystal, at least comprising a refractory crucible arranged along the outer periphery of the noble metal crucible; a seed crystal arranged at the tip, By pulling from the surface, a pulling axis for growing the single crystal under the seed crystal, and the pulling axis can move together with the pulling axis in a direction parallel and perpendicular to the pulling axis, and An insulated furnace that stores the crystal and cools the single crystal, and has a function of adjusting a supply rate of the raw material of the single crystal;
A raw material supply device for supplying the single crystal raw material into the noble metal crucible; and the growing furnace is disposed on the refractory crucible, and has a hole through which the pulling shaft can be opened and closed. An apparatus for producing a single crystal, further comprising a growth furnace upper lid, wherein a bottom portion of the heat insulation furnace can be brought into close contact with an upper part of the growth furnace upper lid. 2. A length of the single crystal in the pulling axis direction in the heat retaining furnace is sufficiently longer than a length of the single crystal in the pulling axis direction, and a center of the single crystal is arranged at a center of the heat retaining furnace. The single crystal manufacturing apparatus according to claim 1, wherein the temperature fluctuation range on the pulling axis in a region from the upper end to the lower end of the single crystal in the case of performing the above is 50 ° C. or less. 3. The length of the single crystal in the direction of the pulling axis in the heat retaining furnace is substantially three times as long as the length of the single crystal in the direction of the pulling axis. Single crystal manufacturing equipment. 4. The single crystal moves from the growing furnace to the heat insulating furnace when the temperature of the center of the heat insulating furnace is set to a temperature 0.7 to 1 times the melting point (absolute temperature) of the single crystal. The single crystal manufacturing apparatus according to claim 1, wherein the temperature distribution on the pulling axis in the region to be reduced monotonously decreases from the growing furnace to the insulated furnace. 5. The apparatus for producing a single crystal according to claim 4, further comprising a heat insulating material surrounding an outer periphery of an upper portion of said growing furnace and an outer periphery of a lower portion of said heat insulating furnace, respectively. 6. The apparatus for producing a single crystal according to claim 1, further comprising a heat insulation furnace bottom cover for closing a bottom of the heat insulation furnace. 7. The apparatus for producing a single crystal according to claim 6, further comprising a powder having the same component as that of said single crystal disposed on the uppermost portion of said thermal insulation furnace bottom cover. 8. A first step of melting a raw material of the single crystal contained in a noble metal crucible disposed inside a growth furnace for growing a single crystal to form a raw material melt; A second step of bringing a seed crystal disposed at the tip of the pulling axis into contact with the liquid surface of the third crystal; a third step of growing a single crystal below the seed crystal by pulling the pulling axis; After reaching a predetermined length, a fourth step of separating the single crystal from the liquid surface, moving the single crystal from the growing furnace to the insulated furnace at a predetermined speed, and placing the single crystal in the insulated furnace A fifth step of vertically moving the single crystal, the pulling shaft, and the heat retaining furnace in a direction perpendicular to the pulling axis; and cooling the single crystal in the heat retaining furnace. The seventh step to be performed, and in the noble metal crucible Eighth to replenish the raw materials of the serial single crystal
And a step of producing a single crystal. 9. The third step is carried out in a state in which an openable and closable growth furnace upper lid having a hole through which the pull-up shaft is provided is closed on the growth furnace and the fourth step and the fifth step are performed. The method for producing a single crystal according to claim 8, further comprising a step of opening the growth furnace top cover between the steps. 10. In the fifth step, the distance from the bottom of the heat-retaining furnace to the top of the growth furnace top is 20 m.
10. The method for producing a single crystal according to claim 9, wherein m is not more than m. 11. The single crystal manufacturing method according to claim 10, wherein in the fifth step, a bottom portion of the heat insulating furnace is in close contact with an upper portion of the growth furnace upper cover. 12. In the fifth step, the temperature at the center of the heat-retaining furnace is set to a temperature of 0.7 to 1 times the melting point (absolute temperature) of the single crystal, and the temperature from the growing furnace to the heat-retaining furnace is set. 9. The single crystal according to claim 8, wherein the predetermined speed in a region where the temperature on the pulling shaft is lower than the temperature of the center of the heat retaining furnace is higher than the predetermined speed in other regions. Production method. 13. In the fifth step, the predetermined speed until the vicinity of the center of the single crystal reaches a point where the temperature distribution in the axial direction of pulling reaches a point near the center temperature of the insulated furnace is 5 mm or less per minute. The method for producing a single crystal according to claim 8, wherein 14. The single crystal according to claim 8, wherein, in the fifth step, the center of the single crystal housed in the insulated furnace is located above the center of the insulated furnace. Production method. 15. A step of attaching, to the bottom of the heat-retaining furnace, a heat-insulating furnace bottom lid in which powder having the same component as the single crystal is disposed at the top between the fifth step and the seventh step. 9. The method for producing a single crystal according to claim 8, further comprising: landing the single crystal on the bottom lid of the heat-retaining furnace. 16. A growth furnace for growing a single crystal, comprising at least a noble metal crucible accommodating a raw material melt, a seed crystal arranged at a tip, and the seed crystal being moved from the liquid level of the raw material melt. By pulling, a pulling axis for growing the single crystal below the seed crystal, a hole through which the pulling axis penetrates is formed in the upper part, and together with the pulling axis in a direction parallel and perpendicular to the pulling axis. An insulated furnace that can be moved and accommodates the grown single crystal and cools the single crystal; a growth furnace storage container surrounding side and bottom surfaces of the growth furnace; and an upper part of the growth furnace storage container A hermetic container for closing the growth furnace from the outside air, the hermetic container being provided with an openable and closable airtight cover having a hole through which the pulling shaft penetrates, and a gas for introducing an inert gas into the airtight container. Fewer inlets And also has a bottom portion of the heat retaining furnace, a single crystal manufacturing apparatus characterized by can be closely above the airtight lid. 17. The apparatus according to claim 1, further comprising a heat-insulating furnace upper lid having a small tube capable of closing the hole formed in the upper part of the heat-insulating furnace and allowing the pull-up shaft to pass therethrough.
7. The single crystal production apparatus according to 6. 18. The airtight opening / closing lid is provided with a pair of openable / closable blades slidable in a direction perpendicular to the pulling shaft and at a predetermined interval in a direction perpendicular to the sliding direction of the openable / closable blade. 17. The single crystal manufacturing apparatus according to claim 16, comprising a fixed blade arranged. 19. The growth furnace according to claim 16, wherein the growth furnace further comprises a freely openable and closable growth furnace upper lid disposed above the refractory crucible and having a hole through which the pulling shaft passes. Crystal manufacturing equipment. 20. The growth furnace upper lid is disposed with a pair of openable and closable blades slidable in a direction perpendicular to the pulling axis and at a predetermined interval in a direction perpendicular to the sliding direction of the openable and closable blade. 20. The apparatus for producing a single crystal according to claim 19, further comprising a fixed blade. 21. The single crystal source according to claim 16, further comprising a raw material supply device for supplying the single crystal raw material into the noble metal crucible, having a function of adjusting a supply speed of the single crystal raw material. Crystal manufacturing equipment. 22. The single crystal producing apparatus according to claim 21, wherein the raw material supply apparatus supplies the single crystal raw material through a tube arranged on a substantially central axis of the growing furnace.