KR100448923B1 - Apparatus and method for producing a single crystal - Google Patents

Abstract

The present invention relates to a single crystal production apparatus and a single crystal production method, and more particularly, to a single crystal production apparatus having a growth furnace in which single crystals are grown and a heat retention furnace for cooling the grown single crystals, wherein single crystal production is performed to grow the next single crystal while cooling the single crystal. A method of manufacturing a single crystal comprising: a growing furnace in which single crystals are grown, a lifting shaft, a warming furnace in which the grown single crystals are stored, and a raw material supply device for supplying raw materials of single crystals into a precious metal crucible; The growing furnace has at least a top opening cover for freely opening and closing with a precious metal crucible containing a raw material melt, a refractory crucible disposed along the outer circumference of the precious metal crucible, and a refractory crucible disposed therein and having a hole through which the lifting shaft penetrates. The bottom part of the heating furnace is brought into close contact with the upper part of the upper cover of the furnace. It is to provide a single crystal manufacturing apparatus capable of simultaneously carrying out the cooling of the single crystal and the growth of the next single crystal at the bottom of the heat retention furnace to receive the single crystal from the growth furnace in close contact with the upper portion of the upper cover of the growth furnace. It features.

Description

Single crystal manufacturing device and single crystal manufacturing method {APPARATUS AND METHOD FOR PRODUCING A SINGLE CRYSTAL}

The present invention relates to a single crystal production apparatus and a single crystal production method, and more particularly, to a single crystal production apparatus having a growing furnace for growing single crystals and a heat retention furnace for cooling the grown single crystals, and producing single crystals for growing the next single crystal while cooling the single crystals. It is about a method.

Conventionally, since oxide single crystals such as lithium tantalate (LiTaO ₃ ) and lithium niobate (LiNbO ₃ ) have a relatively high melting point, nitrogen or a noble metal crucible made of platinum (Pt), platinum-rhodium, or iridium (Ir) is used. Production by the Czochralski method in the atmosphere of inert gas, such as argon, is generally performed.

17 is a cross-sectional view showing the structure of a conventional apparatus for producing an oxide single crystal. In the precious metal crucible 105, a molten single crystal raw material (raw material melt) 113 is accommodated, and under a predetermined temperature condition, the seed crystal 116 is pulled up from the surface of the raw material melt 113 and placed below the seed crystal 116. The single crystal 117 can be grown.

The grown single crystal 117 is subjected to so-called slow cooling, which is cooled for a long time with about half of the raw material melt remaining in the crucible 105 in the growth furnace 101. Usually, one day or more time is required for cooling of a single crystal. 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 supplied as a powdery sintered raw material, and the preparation of the next single crystal is prepared. In addition, since the noble metal crucible 105 made of iridium or the like is easily oxidized at a high temperature, the growth furnace 101 is generally housed in the SUS chamber 124 to form crystal growth.

By the way, since the cooling of the single crystal 117 is performed in the growth furnace 101, half of the raw material melt 113 left in the noble metal crucible 105 is also simultaneously cooled and solidified. When the raw material melt 113 in the noble metal crucible 105 is solidified for each growth of the oxide single crystal, deformation of the noble metal crucible 105 occurs at an early stage, and the crucible must be opened frequently and made again. When the heat cycle of the temperature increase-cooling of the entire growth furnace 101 is repeatedly performed for each growth of the oxide single crystal, the refractory used as the thermal insulation material in the growth furnace 101 is likely to cause heat short cracking, The lifespan, moreover, shortens the lifespan of the development furnace 101. Therefore, the consumption speed of these device components is increased, and as a result, the manufacturing cost of the single crystal increases.

In addition, the oxide single crystal after growth is cracked due to thermal stress when a sudden temperature change is applied (cracking occurs), and thus the cooling requires a long time. In addition, since cooling of the oxide single crystal is performed in the growth furnace 101, preparation for growing the next oxide single crystal cannot be started until the cooling of one oxide single crystal is completed and taken out of the growth furnace 101. Therefore, only one or less oxide single crystals can be produced per day, the production efficiency of the device is low, and the production cost of the oxide single crystals increases. Reference numeral 106 denotes a refractory crucible, 110 an induction heating coil, 111 a reflector tube, 112 an after-motor, 114 an impression rod, 115 an alumina rod, 122 a load cell, and 123 a gas introduction port.

The present invention has been made to solve the problems of the prior art, and an object thereof is to provide a single crystal production apparatus and a single crystal production method which can suppress the production cost of a single crystal low.

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

It is another object of the present invention to provide a single crystal manufacturing apparatus and a single crystal manufacturing method capable of maintaining a long life of the device component.

Another object of the present invention is to provide a single crystal production apparatus and a single crystal production method which can simultaneously perform cooling of single crystal and growth of the next single crystal.

1 is a cross-sectional view showing the configuration of a single crystal production apparatus according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view showing a main manufacturing process in the single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. 1 (of which 1);

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

4 is a cross-sectional view showing a main manufacturing process in the single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. 1 (of which 3);

FIG. 5 is a flowchart (1 of them) showing a single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. 1;

FIG. 6 is a flowchart (2 of them) showing a single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. 1;

FIG. 7A is a graph showing the temperature distribution on the lifting shaft from the growing furnace to the warming furnace in step S07 shown in FIG. 5, and FIG. 7B is a view of the single crystal manufacturing apparatus shown in FIG. A cross-sectional view showing a portion, showing a position of a single crystal at a major temperature of the graph shown in FIG.

FIG. 8A is a graph showing the temperature distribution on the lifting shaft from the growth furnace to the insulation furnace in a state where the bottom of the insulation furnace and the upper part of the growth furnace upper cover are not in close contact with each other according to the first experimental example. (B) shows the position of the single crystal at the main temperature of the graph shown in (a) of FIG. 8, and is a cross-sectional view showing a part of the single crystal manufacturing apparatus shown in FIG.

9A is a graph showing the temperature distribution on the lifting shaft from the growth furnace to the warming furnace in accordance with the third experimental example, and FIG. 9B is a single crystal at the main temperature of the graph shown in FIG. A cross-sectional view showing a position of the single crystal manufacturing apparatus shown in FIG.

(A) is a graph which shows the temperature distribution on a lifting shaft in the state which opened the bottom part of the heat retention furnace which concerns on 4th experiment example, and FIG. 10 (b) shows the growth path and the growth path of the state which opened the bottom part. Cross-sectional view showing a single crystal housed,

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

FIG. 12 is a cross-sectional view showing a main manufacturing process in the single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG.

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

FIG. 14 is a cross-sectional view showing a main manufacturing process in the single crystal manufacturing method using the single crystal manufacturing apparatus shown in FIG. 11 (of which 3);

FIG. 15 is a plan view showing the configuration of the upper furnace top cover shown in FIG. 11, and FIG. 15A illustrates a state in which the upper furnace cover is closed, and FIG. 15B is a state in which the upper furnace cover is opened. Drawing,

FIG. 16 is a plan view showing the structure of the airtight opening and closing cover shown in FIG. 11, and FIG. 16A shows a state where the airtight opening and closing cover is closed, and FIG. 16B is a state where the airtight opening and closing cover is opened. Drawing, and

It is sectional drawing which shows the structure of the single crystal manufacturing apparatus which concerns on a prior art.

Explanation of symbols on the main parts of the drawings

1, 51: nurturing furnace 2, 52: warming furnace

3, 53: insulation bottom cover 4: lid

5: precious metal crucible 6: refractory crucible

7: insulation tower 8, 58: upper cover

10: induction heating coil 11: reflector

12: after heater 14: lifting rod

15: alumina rod 16: seed crystal

17, 17A, 17B, 17C: Monocrystalline 18: Shoring

19: raw material supply device 20, 70: raw material supply pipe

21: sintered raw material 23, 73: gas inlet

24, 58c, 59c: hole 25: suspension

26: liquid level 27: kink of temperature distribution

28: interval 29: center

30: thermal insulation material 54: nurturing furnace storage container

55: base 57: quartz ring

59: airtight opening and closing cover 60: heat insulation top cover

61: refractory ring 69: raw material supply container

In order to achieve the above object, a first feature of the present invention is to provide a raw material for single crystal in a growth furnace in which single crystals are grown, a lifting shaft, a heated single crystal, and a thermal furnace in which single crystals are cooled, and a precious metal crucible. It is a single crystal manufacturing apparatus having at least a raw material supply site. The growth furnace includes at least a precious metal crucible in which the raw material melt is accommodated, and a refractory crucible disposed along the outer circumference of the precious metal crucible. A seed crystal is arranged at the tip of the lifting shaft, and the seed crystal is pulled from the liquid level of the raw material melt to grow a single crystal under the seed crystal. The thermal furnace can move with the lifting shaft in directions parallel and perpendicular to the lifting shaft. The raw material feeder has a function of controlling the feed rate of the single crystal raw material.

The seed crystals are brought into contact with the liquid level of the raw material melt contained in the noble metal crucible to raise the lifting shaft to grow single crystals under the seed crystals. The single crystal grown to a predetermined length is cut off at the liquid level of the raw material melt. The single crystal is moved from the growth furnace into the heat retention furnace and stored in the heat retention furnace.

According to the first aspect of the present invention, since the single crystal is cooled in the thermal furnace, the heat cycle of temperature-cooling of the entire growth furnace is repeatedly performed for each growth of the single crystal without the raw material melt in the noble metal crucible being solidified for each cooling of the single crystal. There is no need to do it. Therefore, it is possible to prevent premature deformation of the precious metal crucible and premature deterioration of the refractory contained in the growth furnace.

When the single crystal is cooled in the heat retaining furnace, another lifting shaft can be arranged in the growth furnace by moving the heat retaining furnace vertically with respect to the lifting shaft together with the single crystal and the lifting shaft. Therefore, preparation for growing the next single crystal can be started while cooling the single crystal. In addition, in order to replenish the single crystal raw material consumed in the precious metal crucible as one of preparations for fostering the next single crystal, use a raw material supply device having a function of controlling the feed rate of the single crystal raw material and use the single crystal raw material for It is good to supply in the inside.

In the first aspect of the present invention, it is preferable that the growth path further has a free-opening growth top cover having a hole through which the lifting shaft disposed on the refractory crucible passes. In addition, it is preferable that the bottom part of the heat retention furnace can be brought into close contact with the upper portion of the upper cover of the furnace. In the state close to the upper part of the upper cover of the growth furnace, the single crystal is accommodated from the growth furnace into the insulation furnace to store the single crystal from the growth furnace into the insulation furnace without applying significant thermal stress to the single crystal. In addition, when the single crystal is grown, the top of the growth furnace is closed to prevent the falling objects from above the growth furnace from infiltrating into the noble metal crucible and to prevent a decrease in the purity of the raw material melt. In addition, even after the single crystal is stored in the heat storage furnace, the growth top cover is closed to prevent falling objects into the precious metal crucible at the same time as the growth of the single crystal.

It is preferable to make the length of the lifting axis direction in a heat retention path substantially 4 times the length of the lifting axis direction of a single crystal. The length of the lifting axis in the heating furnace is sufficiently long compared with the length of the lifting axis of the single crystal, and the temperature fluctuation width on the lifting shaft in the region from the top to the bottom of the single crystal when the center of the single crystal is arranged in the center of the heating furnace is It can be 50 degrees C or less.

It is preferable that the single crystal manufacturing apparatus also have a heat insulating material which surrounds the outer periphery of the upper part of the growth furnace and the outer periphery of the lower part of the heat keeping furnace, respectively. If the center temperature of the heating furnace is set to a temperature of 0.7 to 1 times the melting point (absolute temperature) of the single crystal, the temperature main body on the lifting shaft in the area where the single crystal is moved from the growing furnace to the heating furnace is moved from the growing furnace to the heating furnace. It can be reduced monotonously.

In addition, it is preferable that the single crystal manufacturing apparatus further have a heat insulation bottom cover that blocks the bottom of the heat insulation furnace. The bottom of the growth furnace containing the single crystals can be closed with the bottom of the insulation furnace to cool the entire single crystal at a uniform speed without first cooling the portion near the bottom of the growth furnace of the single crystal. Moreover, it is preferable to arrange | position the powder of the same component as a single crystal on the uppermost part of a bottom of a heat insulation furnace. The single crystal housed in the thermal furnace is landed on the bottom cover of the thermal furnace. Placing powder of the same composition as single crystal on the top of the bottom of the heating furnace prevents reaction between the single crystal in the high temperature state and the bottom cover of the heating furnace, and deteriorates or cracks are generated in the bottom of the single crystal after cooling. You can prevent it.

It is preferable that the inner surface of the thermal insulation furnace is covered with a heat resistant hard to deteriorate material, and the inner surface of the thermal insulation furnace has a configuration in which peeling is unlikely to occur during lifting of the single crystal. The inner surface of the peeled thermal insulation furnace can prevent the fall into the noble metal crucible and can avoid the fall of the purity of the raw material melt.

The second feature of the present invention

(1) a first step of forming a raw material melt by melting a single crystal raw material housed in a noble metal crucible disposed inside a growth furnace in which single crystals are grown;

(2) a second step of bringing the seed crystal disposed at the tip of the lifting shaft into contact with the liquid surface of the raw material melt;

(3) the third step of raising the lifting axis to grow a single crystal under the seed crystal;

(4) a fourth step of cutting the single crystal off the liquid level after the single crystal reaches the predetermined length,

(5) a fifth step of moving the single crystal from the growth furnace to the heat retention furnace at a predetermined speed and storing the single crystal in the heat retention furnace;

(6) a sixth step of synchronizing the single crystal, the lifting shaft and the heat retaining furnace and moving in the vertical direction with respect to the lifting shaft;

(7) a seventh step of cooling the single crystal in the heating furnace, and

(8) It is a single crystal manufacturing method which has at least the 8th step of replenishing a raw material of single crystal in a noble metal crucible.

Here, the seventh step can be performed simultaneously with the eighth step. That is, the eighth step need not be carried out after the cooling of the single crystal of the seventh step is completed, and can be performed before and after the cooling start. Usually, cooling of a single crystal differs depending on the size, material, etc., but may require about 10 hours. When the replenishment of the eighth step is completed during the cooling of the single crystal, the replenishment of the replenished raw material may be performed again with the remaining raw material after lifting to form the raw material melt. In addition, in the sixth step, the lifting shaft is moved together with the single crystal in the direction perpendicular to the axis, so that a separate lifting shaft can be prepared after the first step, and the second step can be continuously performed.

The 3rd step is arrange | positioned on a build-up path, it is carried out in the state which closed the free-opening development top cover which has a hole which a lifting shaft penetrates, and opens the growth top cover between a 4th step and a 5th step. It is desirable to have. Here, the growth furnace upper cover may be in a closed state at least in the third step, and preferably in the closed state in the first and second steps and the fourth step.

In a 5th step, it is preferable that the distance from the bottom part of a heat retention furnace to the upper part of a growth furnace upper cover is 20 mm or less. More preferably, the bottom portion of the heat retention furnace is in close contact with the upper portion of the upper cover of the growth furnace.

In the fifth step, the center temperature of the heating furnace is set at a temperature of 0.7 to 1 times the melting point (absolute temperature) of the single crystal, and in the region where the temperature on the lifting shaft from the growth furnace to the heating furnace is less than the temperature of the center of the heating furnace. The predetermined speed is preferably faster than the predetermined speed in other areas.

In the fifth step, the speed is preferably 5 mm or less per minute until the vicinity of the center of the single crystal reaches the point near the center temperature of the heat retaining furnace.

In the 5th step, it is preferable that the center of the single crystal accommodated in the heat retention furnace is located above the center of a heat retention furnace.

Between the fifth step and the seventh step, a step of mounting the bottom cover of the heat insulating furnace in which powder of the same component is disposed on the top of the bottom of the heat holding furnace and a step of landing of the single crystal on the bottom cover of the heating furnace; It is desirable to have. Here, these steps should just be between a 5th step and a 7th step, and it is preferable to implement after a 6th step.

The third aspect of the present invention is to provide a growth furnace for growing single crystals, a heating shaft for holding the lifting shaft and the grown single crystals to cool the single crystals, an airtight container for blocking the growth furnaces from outside air, and an inside of the airtight container. It is a single crystal manufacturing apparatus which has at least the gas introduction port which introduces an inert gas into a furnace. The growth furnace includes at least a noble metal crucible containing the raw material melt. A seed crystal is arranged at the tip of the lifting shaft, and the seed crystal is lifted from the liquid level of the raw material melt to grow the single crystal under the seed crystal. A hole through which the lifting shaft penetrates is formed in an upper portion of the heating furnace, and the heating furnace can move together with the lifting shaft in a direction parallel and perpendicular to the lifting shaft. The airtight container includes a growth path storage container surrounding side and bottom surfaces of the growth path, and an airtight opening / closing cover that is close to an upper portion of the growth path storage container and has a hole through which the lifting shaft passes. The bottom of the heating furnace may be in close contact with the top of the airtight opening and closing cover.

The hermetic container shuts off the growth furnace with a precious metal crucible that is relatively oxidized at high temperatures. On the other hand, the warming furnace and the single crystal housed in the heating furnace are exposed to the atmosphere. By bringing the bottom of the heat retention furnace close to the upper part of the airtight opening and closing cover, approximately the entire inert gas introduced into the airtight vessel flows into the interior of the heat retention furnace and is released into the atmosphere from the hole formed in the top of the heat retention furnace.

According to the third aspect of the present invention, it is possible to efficiently block the surroundings of the growth furnace including the noble metal crucible which is relatively easy to oxidize in a high temperature state from the outside air atmosphere. As the life of the (2) precious metal crucible and the refractory member becomes longer, the manufacturing cost can be reduced.

(1st embodiment)

Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, similar parts are denoted by similar parts to the prior art. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the structure of the single crystal manufacturing apparatus which concerns on 1st Embodiment of this invention. The single crystal manufacturing apparatus accommodates the growth furnace 1 in which the single crystals 17 are grown, the thermal crystal furnace 2 and the seed crystals 16 in which the slow growth of the single crystals 17 is carried out by storing the grown single crystals 17. Lifting shafts 14 to 16 which are pulled up from the liquid surface 26 of a single crystal raw material (raw material melt) 13 to grow the single crystal 17 are provided.

The growth furnace 1 consists of a noble metal crucible 5 in which the raw material melt 13 is accommodated, a ring-shaped reflecting plate 11 made of a noble metal disposed on the noble metal crucible 5, and a noble metal disposed on the reflecting plate 11. After-heater (12), refractory crucible (6) consisting of a heat insulating material including a refractory disposed on the outer periphery of the noble metal crucible (5), a thermal insulation tower (7) disposed on the refractory crucible (6) and thermal insulation The top cover 8 is provided with a free-opening growth path having a hole 24 disposed on the tower 7 and through which the lifting shafts 15 and 16 pass. The growth furnace upper cover 8 has a structure divided into two, and can move the growth furnace upper cover 8 to the left and right to operate the opening and closing of the growth furnace upper cover 8 from the outside of the apparatus. The refractory crucible 6, the heat insulation tower 7, and the growth furnace upper cover 8 are comprised by the heat insulating material. Induction heating coils 10 are arranged on the outer periphery of precious metal members such as the precious metal crucible 5, the reflecting plate 11, the after heater 12, and at a predetermined interval from the refractory crucible 6. The induction heating coil 10 heats and heats up the precious metal members 5, 11, and 12, melts the raw material of the single crystal in the precious metal crucible 5, and is suitable for growing the single crystal 17 in the growth furnace 1. Form a distribution. The growth path 1 is supported by a support 18.

The noble metal crucible 5 uses the crucible made from iridium (Ir) of diameter 180mm (phi) and height 150mm. Instead of iridium (Ir), a platinum (Pt), a platinum rhodium (Pt-Rb) alloy, or the like may be used as the material. The single crystal raw material contained in the noble metal crucible 5 consists of a sintered material sintered by weighing powders of lithium carbonate (Li ₂ CO ₃ ) and tantalum oxide (Ta ₂ O ₅ ). The weight of the sintered material is 7 ~ 10kg, the total weight of the precious metal crucible (5) and the sintered material is 15kg. In addition, lithium carbonate (Li ₂ CO ₃ ) and tantalum oxide (Ta 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 insulating furnace 2 is arrange | positioned above the growth furnace 1, and the opening part for accommodating the single crystal 17 in a growth furnace is formed in the bottom part. The heat retaining furnace 2 is a direction in which the single crystal 17 is pulled up, that is, a direction parallel to the lifting shafts 14 to 16 (hereinafter referred to as the "lifting shaft direction") and perpendicular to the lifting shafts 14 to 16. It can move to a phosphorus direction (henceforth a "lifting axis vertical direction"). A suspending means 25 for moving the growth path 1 in the lifting axis direction is connected to the upper portion of the growth path 1. By using this suspending means 25, the bottom of the heat retaining furnace 2 can be brought into close contact with the growth top cover 8.

Moreover, the heat insulating material is contained in the material which comprises the heat retention furnace 2, and has a function which maintains the temperature in the heat retention furnace 2. As shown in FIG. In addition, the heat retaining furnace 2 has heating means for forming a high temperature state necessary for storing the single crystal 17. The inner surface of the heat retainer 2 is covered with a heat resistant hard to deteriorate material, such as a KM tube (manufactured by Nikkato Co., Ltd.). Since the heat retaining furnace 2 is disposed above the growth furnace 1, the inner surface of the heat retaining furnace 2 is prevented from peeling off and mixed into the precious metal crucible 5, and the purity of the raw material melt 13 is lowered. Prevent it. In addition, in order to form a wide area | region (cracking area) with a uniform temperature in the heat retention furnace 2, it is preferable that the furnace length of a lifting axis direction is three times or more of the length of the single crystal 17. As shown in FIG. In 1st Embodiment, since the length of the single crystal 17 was about 10 cm, the length of the furnace of the heat retention furnace 2 was 40 cm. When the center temperature of the heat retainer 2 is set to 1300 ° C. by using the heating means of the heat retainer 2, the temperature of an area of 15 cm from the center of the heat retainer 2 in the lifting axis direction is 1300 ± 50. It was confirmed that a crack region staying in the range of ° C was formed.

The lifting shaft consists of a lifting rod 14, an alumina rod 15, and a seed crystal 16. One end of the alumina rod 15 is connected to one end of the lifting rod 14. The seed crystal 16 is connected to the other end of the alumina rod 15. The lifting rod 14, the alumina rod 15, and the seed crystal 16 are connected in a linear shape. The other end of the lifting 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 penetrates the hole 24 of the heat retaining furnace 2 and the growth furnace upper cover 8, and receives the seed crystal 16 disposed at the tip of the lifting shaft in the precious metal crucible 5 The liquid surface 26 of 13 can be contacted.

The growth furnace 1, the heat retention furnace 2, and the lifting shafts 14-16 are arrange | positioned in the metal container (chamber made from SUS) 35. As shown in FIG. The inside of this container is filled with inert gas, such as nitrogen and argon, which are introduced from the gas inlet 23. On the outside of the metallic container, a raw material supply device 19 having a function of controlling the supply speed of the raw material of the single crystal 17 and a weight sensor is disposed. 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 precious metal crucible 5 in the growth furnace 1. The sintered material 21 in the raw material supply device 19 is a powder or granular raw material.

Further, a round plate-shaped or rectangular-shaped lid 4 is placed outside the metallic container, and an insulating furnace bottom lid 3 mounted on the lid 4 at the bottom of the insulating furnace 2 is disposed. The warming bottom lid 3 can be inserted together with the lid 4 into the metallic container. Thermal insulation bottom cover 3 has a built-in heating means, it can control its temperature.

Next, a method of producing a single crystal using the single crystal manufacturing apparatus shown in FIG. 1 will be described with reference to FIGS. 1 to 11. 1 to 4 are device cross-sectional views showing the 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. 5 is a flowchart showing a method for producing a single crystal.

(A) First, in step S01 shown in FIG. 5, the tip of the raw material supply pipe 20 extends so as to be on the noble metal crucible 5, and Li ₂ CO ₃ and Ta _{2 in the} raw material supply device 19. The powder of O ₅ is weighed and sintered, and the sintered material 21 is supplied to the noble metal crucible 5 through the raw material supply pipe 20. In addition, it is preferable to supply the sintered raw material 21 while rotating the precious metal crucible 5. When the sintered raw material 21 supplied to the noble metal crucible 5 takes some time to melt and is continuously supplied without rotation, the sintered raw material 21 is sequentially turned on the sintered raw material 21 before melting. This is because there is a case that the sintered raw material 21 does not melt smoothly.

(B) Next, in step S02, the electric power applied to the induction heating coil 10 is increased, and the precious metal members 5, 11, 12 in the growth furnace 1 are heated. The sintered raw material is melted completely and the raw material melt 13 is formed. Then, the electric power applied to the induction heating coil 10 is controlled, and the temperature of the liquid surface 26 of the raw material melt 13 is adjusted to a temperature suitable for growing single crystals. In addition, the temperature distribution in the growth furnace 1 is smoothed in a state in which the growth furnace upper cover 8 is covered to form a temperature distribution suitable for growth of the single crystal.

(C) Next, in step S03, the lifting shafts 14 to 16 are moved toward the raw material melt 13, and the seed crystal 16 at the tip of the lifting shaft is moved to the liquid level 26 of the raw material melt 13. ). Next, in step S04, as shown in FIG. 1, the lifting top 14 is closed while the lifting shafts 14 to 16 are rotated while the upper cover 8 is closed, and the single crystal 17 is below the seed crystal 16. As shown in FIG. Foster).

(D) Next, after the single crystal 17 is grown to a predetermined length in step S05, the single crystal 17 is cut off from the liquid surface 26. The cutting of the single crystal 17 may be performed by lifting the lifting shafts 14 to 16 to a predetermined distance at a high speed of 10 to 100 mm / min. Further, a method of forming a crystal tail at the lower end of the single crystal 17 and cutting it off from the liquid surface 26 may be used.

(E) Next, preparation for moving the grown single crystal 17 from the growth furnace 1 to the heat retention furnace 2 is performed. First, the temperature in the heat retention furnace 2 is set to the predetermined temperature required for accommodating the single crystal 17 in the high temperature state immediately after the growth. That is, when the melting point of the single crystal 17 is Tm in the absolute temperature display, the center temperature of the heat keeping furnace 2 is set to a temperature of 0.7Tm or more and less than Tm. Here, description is continued about the case where the temperature of the center of the heat retention furnace 2 is set to 1300 degreeC. In addition, in 1st Embodiment, although preparation for moving the grown single crystal 17 from the growth furnace 1 to the heat retention furnace 2 is performed after step S05, it is not limited to this, of course. You may carry out in the middle of growing the single crystal 17 before step S05.

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

(G) Next, in step S08 shown in FIG. 6, the growth furnace upper cover 8 is closed. Next, in step S09, the single crystal 17, the lifting shafts 14 to 16, and the heat retaining furnace 2 are synchronized (moving) in the lifting axis direction. Next, in step S10, as shown in FIG. 3, the heat insulation bottom cover 3 is attached to the bottom part of the heat insulation furnace 2. As shown in FIG. Specifically, after the single crystal 17, the lifting shafts 14 to 16, and the heat retaining furnace 2 are moved (rising) until the bottom of the heat retaining furnace 2 is above the heat retaining bottom cover 3, the heat retaining furnace The bottom cover 3 is moved together with the round plate-shaped cover 4 in the vertical direction of the lifting shaft, and is disposed below the heat retaining furnace 2. Then, the single crystal 17, the lifting shafts 14 to 16, and the heat retaining furnace 2 are lowered, and the heat retainer bottom cover 3 is attached to the bottom of the heat retaining furnace 2. Next, in step S11, the single crystal 17 is landed on the bottom cover 3 of the heat retention furnace.

(H) Next, in step S12, the single crystal 17, the lifting shafts 15 and 16, and the heat retaining furnace 2 are synchronized with each other to move in the vertical direction of the lifting shaft. Specifically, first, the heat retaining furnace 2 and the suspension means 25 are cut off, and the lifting rod 14 and the alumina rod 15 are cut off. Then, the alumina rod 15, the seed crystal 16, the single crystal 17, the heat insulating bottom cover 3, the lid 4 and the heat holding furnace 2 are moved in the vertical direction of the lifting shaft in synchronization with each other. Move it out.

(I) Next, in step S13, the single crystal 17 is cooled in the heat retention furnace 2. Specifically, the temperature of the heating furnace 2 is dropped to room temperature at a constant rate over about 10 hours. Then, after cooling of the single crystal 17 is completed, the single crystal 17 is taken out of the heat retaining furnace 2 six hours later. Next, in step S14, it is determined whether to grow the next single crystal simultaneously with step S13. When the next single crystal growth is carried out (YES in step S14), the flow advances to step S15, in which the amount of the single crystal raw material (sintered raw material) 21 consumed by the growth of the single crystal 17 is noble metal. It is replenished in the crucible 5. Since the weight of the raw material melt 13 consumed by the growth of the single crystal 17 is the weight of the single crystal 17 measured by the load cell 22, the same weight of the sintered raw material 21 as the single crystal 17 is obtained. Disseminate. At this time, the sintered raw material 21 is replenished while rotating the precious metal crucible 5 (while rotating the supporting rod 18).

(D) Next, in step S16, as shown in Fig. 4, a new alumina rod 15 and seed crystal 16 are mounted on the lifting rod 14, and the next lifting shaft is prepared. Then, the process returns to step S02 and the above steps S02 to S13 are repeated. On the other hand, when the next single crystal growth is not carried out (NO in step S14), the series of single crystal production methods is completed.

FIG. 7A is a graph showing the temperature distribution on the lifting shaft from the growth furnace 1 to the heat retention furnace 2 in step S07. The vertical axis represents the vertical distance at the liquid level 26 of the raw material melt 13, and the horizontal axis represents the temperature on the lifting axis. The temperature on the lifting shaft is measured by using a thermocouple in a state in which the growth furnace upper cover 8 is opened and the growth furnace in which the core temperature is set to 1300 ° C. is in close contact with the growth furnace upper cover 8. 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 17 at the main temperature of the graph shown in FIG. 7A.

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 lifting shaft decreases with the vertical distance. It is less than 1300 degreeC near the upper part of the thermal insulation tower 7, and forms the kink (minimum value) 27 of temperature distribution in the vicinity of the bottom part of the growth furnace 2, and at the center of the thermal insulation furnace 2 It is rising to 1300 degreeC. In FIG.7 (b), single crystal 17A shows the state cut | disconnected by the liquid level 26 in step S05. The single crystal 17B shows a state in which the center 29 of the single crystal 17 is arranged at a portion where the temperature on the lifting shaft becomes 1300 ° C. near the upper end of the thermal insulation tower 7. The single crystal 17C represents a state in which the center 29 of the single crystal 17 is disposed at the center of the heat keeping furnace 2.

In the first embodiment of the present invention, in step S07, the moving speed from the growth furnace 1 to the heat retention furnace 2 is a region where the temperature on the lifting shaft is less than the temperature (1300 ° C.) at the center of the heat retention furnace 2, and It differs in the other area | region, and the area | region below the inside temperature (1300 degreeC) of the heat-retaining furnace 2 center is faster. That is, in FIG. 7B, the moving speed from the state of the single crystal 17B to the state of the single crystal 17C is faster than the moving speed from the state of the single crystal 17A to the state of the single crystal 17B. Specifically, it took 1 hour from the state of single crystal 17A to the state of single crystal 17B, and rapidly moved from the state of single crystal 17B to the state of single crystal 17C at a speed of 50 to 100 mm per minute. In addition, although the movement time was 1 hour from the state of the single crystal 17A to the state of the single crystal 17B, it is preferable to move for a longer time from the viewpoint of reducing the thermal stress and preventing the crack that the single crystal 17 receives. .

As described above, according to the first embodiment of the present invention, the raw material melt 13 in the noble metal crucible 5 is fixed for each cooling of the single crystal 17 in order to cool the single crystal 17 in the heating furnace 2. It is not necessary to repeat the heat cycle of temperature raising and cooling of the entire growth furnace 1 for each growth of the single crystal 17. Therefore, premature deformation of the precious metal crucible 5 and premature deterioration of the refractory contained in the growth furnace 1 can be prevented. Thereby, the improvement of the production capacity of the single crystal 17 and the substantial reduction of the production cost can be achieved simultaneously.

In addition, when cooling the single crystal 17 in the heat retaining furnace 2, the heat retaining furnace 2 is moved together with the single crystal 17 and the lifting shafts 15 and 16 in the vertical direction with respect to the lifting shaft. Other lifting shafts can be arranged in the build furnace 1. Therefore, preparation for growing the next single crystal can be started while cooling the single crystal 17. Therefore, continuous crystal lifting becomes a practical level, and it is possible to manufacture single crystals produced at one ratio in conventional two days at one ratio per day, so that the production efficiency of the single crystal manufacturing apparatus is doubled conventionally.

In addition, in the state in which the bottom part of the heat retaining furnace 2 is in close contact with the upper part of the growing furnace upper cover 8, the single crystal 17 is stored in the heat retaining furnace 2 in the growing furnace 1, and The heat in a furnace can make it hard to run away from the space | interval with the thermal furnace 2. That is, the single crystal 17 is not grown in the vicinity of the gap between the growth top cover 8 and the heat retaining furnace 2, and the single crystal 17 is grown without applying a large thermal stress to the single crystal 17. Housed in the thermal furnace (2). Therefore, the incidence rate of single crystal cracks can be greatly reduced.

In addition, when the single crystal 17 is grown, the growth furnace upper lid 8 is closed to prevent falling objects from entering the precious metal crucible 5 from the upper portion of the growth furnace 1 and to improve the purity of the raw material melt 13. The fall can be prevented. Also, after storing the single crystal 17 in the heat retaining furnace 2, the growth top lid 8 is closed to prevent falling objects into the precious metal crucible 5 in the same manner as the single crystal 17 is grown. have.

In addition, when preparing the growth of the single crystal 17, the upper cover 8 of the growth furnace is closed to alleviate the temperature distribution inside the growth furnace 1 in the longitudinal direction, thereby creating a furnace environment suitable for the growth of the single crystal 17. Can be formed. In addition, since the growth furnace upper cover 8 has a hole 24 through which the lifting shafts 14 to 16 penetrate, the growth furnace upper cover 8 can be closed to grow the single crystal 17. Therefore, even in the growth of the single crystal 17, it is possible to maintain the furnace environment suitable for the growth of the single crystal, and to reduce the thermal stress that the single crystal 17 receives.

(Example 1)

Next, an experimental example according to the first embodiment of the present invention will be described. First, in the first experimental example, the distance from the bottom of the heat retaining furnace 2 to the top of the growing furnace upper cover 8 when the single crystal 17 is moved from the growing furnace 1 to the heat retaining furnace 2 is described. Review. In the embodiment, the bottom of the heat retaining furnace 2 is in close contact with the upper part of the growth furnace upper cover 8, that is, the distance from the bottom of the heat retaining furnace 2 to the top of the growth furnace upper cover 8 is 0 mm. One case is shown. In the first experimental example, the single crystal 17 was moved from the growth furnace 1 to the insulation furnace 2 under four conditions of 0, 10, 20, and 40 mm in this distance (the distance between the insulation furnace and the growth furnace). . Three single crystals 17 were grown for each condition, and the crack free rate of the single crystal 17 after cooling and the crack free rate after the polling step were measured. In this measurement, the deviation from the ideal state in the crystal lifting step was excluded from the count of the crack free rate. The measurement results are shown in Table 1.

Distance between insulation furnace and upbringing furnace Crack Free Rate After Cooling Crack Free Rate after Polling 40 mm 1/3 1/1 20 mm 3/3 2/3 10 mm 3/3 3/3 0 mm 3/3 3/3

As shown in Table 1, favorable results were obtained for the crack free rate after cooling on the conditions of 0, 10, and 20 mm. Moreover, although the crack free rate after polling was falling on 20 mm conditions, the favorable result was obtained on 0 and 10 mm conditions. Therefore, it can be seen that in step S07 shown in FIG. 5, the occurrence of cracks can be prevented by setting the distance from the upper part of the growth furnace upper cover 8 to the bottom of the heat retention furnace 2 to 10 mm or less. have. Moreover, it turned out that the crack prevention effect is already exhibited even if this distance is set to 20 mm or less.

FIG. 8A is a graph showing the temperature distribution on the lifting shaft from the growth furnace 1 to the heat retention furnace 2 in step S07 in the same manner as in 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 of the graph shown in FIG. 8A. . However, the distance from the upper part of the upper part of the growth furnace upper cover 8 to the bottom part of the heat retention furnace 2 is not 0 mm, that is, the upper part of the upper part of the growth furnace upper cover 8 and the bottom part of the thermal insulation furnace 2 are not in close contact. It shows the temperature distribution in the absence state. As shown in FIG. 8A, a gap 28 is formed between the upper part of the growth furnace upper cover 8 and the bottom of the heat retaining furnace 2 so that heat in the furnace can escape from the gap 28. This lowers the temperature on the lifting shaft. On the other hand, the temperature of the liquid level 26 of the raw material melt 13 and the center temperature of the heat retention path 2 do not change with respect to 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 upper part of the growth furnace upper cover 8 and the bottom part of the heating furnace 2 becomes large. When the single crystal 17 passes through the kink 27 of this temperature distribution, there is a possibility that a large heat stress is generated and cracks are generated.

(Example 2)

Next, in the 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 retention furnace 2 is examined. In the embodiment, in step S07, as shown in Fig. 7B, the state of the single crystal 17C in the single crystal 17B state is higher than the moving speed from the state of the single crystal 17A to the state of the single crystal 17B. I was speeding up the speed of movement. Thereby, the thermal stress which the single crystal 17 receives in the kink 27 of temperature distribution was able to be reduced.

In the second experimental comparative example, the single crystal 17 was cut off at the liquid level 26 and moved at a constant moving speed to the state where the center 29 of the single crystal 17 was located at the center of the heating furnace 2. The moving speed was 1.5 mm per minute and moved over about 300 minutes.

In addition, the moving speed of the single crystal which concerns on 1st Embodiment is as follows. In other words, the moving speed in the regions 17A to 17B where the temperature on the lifting shaft was at least 1300 ° C. in the center of the heating furnace 2 was 1.5 mm per minute, and moved over about 85 minutes. Then, the moving speed in the regions 17B to 17C where the temperature on the lifting shaft is lower than the center furnace temperature (1300 ° C.) of the heat keeping furnace 2 is quickly sent to 100 mm per minute. Ten single crystals 17 were grown each, and the crack free rate after cooling was examined. The results are shown in Table 2.

Crack free rate Moving speed 4/10 Sent quickly after the furnace temperature 8/10

As shown in Table 2, when the single crystal 17 was slowly moved over time according to the second experimental example (moving speed constant), the crack free rate was 4/10, and the embodiment (after the furnace temperature) Sent quickly), crack free rate was 8/10. That is, the probability that cracks did not occur when sent quickly after the temperature of the heating furnace was twice that of a constant moving speed. This is a cooling part (the kink 27 of temperature distribution) with a locally low temperature is formed between the heat retention furnace 2 and the growth furnace upper cover 8, and when this cooling part is moved slowly, a single crystal ( The temperature of 17) is affected by this cooling part. That is, it is thought that the temperature of the single crystal 17 decreases rapidly, the internal stress of the single crystal 17 increases, and cracks tend to occur.

On the other hand, as shown in the first embodiment, the temperature on the lifting shaft rapidly moves the regions 17B to 17C where the temperature on the lifting shaft 2 is less than the center temperature (1300 ° C) of the heating furnace 2, so that the local cooling portion is the temperature of the single crystal 17. The influence on the surface is small and can be stored in the heat storage furnace 2 while maintaining the temperature of the single crystal 17 at a high temperature to some extent. Therefore, it is thought that since the thermal stress received by the single crystal 17 is small, the probability of cracking can be reduced.

In addition, in the second experimental example, the same experiment was performed on lithium niobate (LiNbO ₃ ) in addition to the single crystal of lithium tantalate (LiTaO ₃ ), and the same result was obtained.

(Third Experimental Example)

As shown in FIGS. 7A and 7B, even when the upper part of the upper part of the growth furnace upper cover 8 and the bottom part of the heat retaining furnace 2 are in close contact with each other, the kink on the temperature distribution on the lifting shaft is in close contact therewith. (27) is formed. As shown in the second experimental example, in order to reduce the thermal stress that the single crystal 17 receives, the single crystal 17 is quickly moved in the temperature distribution kink 27. Thus, in the third experimental example, the temperature distribution on the lifting shaft from the growth furnace 1 to the insulation furnace 2 is monotonously reduced from the growth furnace 1 to the insulation furnace 2 without forming the kink 27. The devise on the apparatus for making a shape is examined.

FIG. 9B is a cross-sectional view showing a part (feature part) of the configuration of the single crystal device according to the third experimental example. As shown in (b) of FIG. 9, the single crystal manufacturing apparatus according to the third experimental example has an outer circumference of the upper portion of the thermal insulation tower 7 and an outer circumference of the lower portion of the thermal insulation furnace 2 as compared with the apparatus of FIG. 1. It also has a heat insulating material 30 surrounding each. Here, an alumina type heat insulating material is used as the heat insulating material 30. FIG. 9A is a graph showing the temperature distribution on the lifting shaft in the apparatus configuration shown in FIG. 9B. As shown in Fig. 9A, the insulation material 30 is disposed so that the kink of the temperature distribution is not formed at the portion where the upper portion of the upper cover 8 of the growth furnace upper cover 8 and the bottom of the insulation furnace 2 are in close contact with each other. From the liquid level 26 of (13), the temperature on a lifting shaft can be monotonously reduced across the center of the heat retention furnace 2.

In the states shown in Figs. 9A and 9B, as in the second embodiment, ten single crystals 17 were grown, and the crack free rate of the single crystals 17 after cooling was measured. At this time, the moving speed moved at a constant speed of 2 mm per minute until the upper end of the single crystal 17 reached near the bottom of the heat retaining furnace 2, and then moved to a rapid sending of 100 mm per minute. Table 3 shows the measurement results.

Crack Free Rate After Cooling After improving temperature distribution 9/10

As shown in Table 3, by improving the temperature distribution, the crack free rate after cooling rose to 9/10, and it was found that the crack free rate was improved compared to 8/10 of the case where the heat was quickly sent after the temperature of the heat keeping furnace of Table 2. .

In addition, three single crystals were grown at four speeds of 1, 3, 5, and 7 mm per minute, respectively, at a moving speed until the upper end of the single crystal 17 reached near the bottom of the heat retaining furnace 2, and after cooling, The crack free rate was measured. Table 4 shows the measurement results.

Ascent rate Crack Free Rate After Cooling 1mm / m 3/3 3mm / m 3/3 5mm / m 2/3 7mm / m 0/3

As shown in Table 4, no crack is generated under the conditions of 1 mm per minute and 3 mm per minute, and there are few cracks under the condition of 5 mm per minute. However, cracks were observed in all single crystals 17 in a condition of 7 mm or more per minute. This is considered to be because the cooling rate of the single crystal 17 is increased, the thermal stress is increased, and cracks are likely to occur.

(Example 4)

Next, the handling of the single crystal 17 after being stored in the heat retaining furnace 2 will be described. As also shown in the embodiment, the length in the lifting axis direction in the thermal furnace 2 is set to 40 cm, which is three times or more the length (about 10 cm) of the single crystal 17, and the temperature is uniform in the thermal furnace 2. The crack area can be formed widely. Therefore, the single crystal 17 can be uniformly cooled by being accommodated in the heat retention furnace 2 so that the center of the single crystal 17 and the center of the heat retention furnace coincide.

However, when the furnace length of the heat retention furnace 2 cannot be made long enough, the problem shown below arises. That is, in step S07, the single crystal 17 is accommodated in the heat retaining furnace 2, and after the single crystal 17 is attached to the bottom of the heat retaining furnace at the step S10, the single crystal 17 is mounted. The silver is housed in the heat retaining furnace 2 in the open state. In addition, in step S09, the heat retention path 2 is moved (rising) in parallel with respect to a lifting shaft, and the bottom part is released from the upper part of the upper part of the upper part of the growth path 8. Therefore, the temperature distribution in the heat retention path 2 between step S07 and step S10 has a shape in which the temperature near the bottom portion has decreased, and the lower end side of the single crystal 17 is cooled first, It may occur.

FIG. 10A is a graph showing the temperature distribution on the lifting shaft in the state where the bottom portion of the heat keeping furnace 2 is opened. FIG. 10B is a cross-sectional view showing the growth path 1 and the single crystal 17 housed in the growth path 1 having the bottom portion opened. As shown in Fig. 10A, when the length of the lifting shaft direction in the heat retaining furnace 2 cannot be lengthened sufficiently, it can be seen that the temperature near the bottom is low in the open state of the bottom. In the temperature distribution shown in (a) of FIG. 10, when the single crystal 17 is arranged so that the center 29 and the center 34 of the heat retaining furnace 2 coincide with each other, the upper end 31 of the single crystal 17 is arranged. There is a risk that the temperature difference between the lower end 32 and the lower end 32 becomes large, the lower end 32 side of the single crystal 17 is first cooled, and cracks may occur.

Thus, as shown in FIG. 10B, the single crystal 17 is stored in the growth furnace 1 such that the center 29 of the single crystal 17 is disposed above the center 34 of the heat keeping furnace 2. do. Alternatively, the single crystal 17 is stored in the growth furnace 2 such that the distance between the bottom of the heat retention furnace 2 and the lower end of the single crystal 17 is equal to or greater than the inner diameter of the heat retention furnace 2. As a result, the temperature difference between the upper end 31 and the lower end 32 of the single crystal 17 can be suppressed to be small, and the single crystal 17 can be placed in a uniform temperature environment, whereby the occurrence of cracks can be suppressed.

(Example 5)

Next, the uppermost material of the heat insulating bottom cover 3 is examined. In general, oxide single crystals tend to react with materials of other materials at high temperatures. In particular, this tendency is strong with respect to oxide single crystals containing lithium (Li), and it has been confirmed that at least the single crystals of LiTaO ₃ and LiNbO ₃ react with alumina in a high temperature state.

Specifically, high-purity alumina wool was placed on the top of the heat insulating bottom cover 3, and in step S11, the single crystal 17 was landed on the heat insulating bottom cover 3 and cooled. After cooling, white blooms or cracks were sometimes generated in the lower portion of the single crystal 17 which was in contact with the bottom cover 3 of the thermal insulation furnace.

Therefore, the single crystal 17 was landed on the heat insulating bottom cover 3 and cooled in the state which arrange | positioned the powder of a single crystal and the same component on the platinum foil in the upper part of the heat insulating bottom cover 3, and cooled. After cooling, no trace of any reaction was seen in the lower portion of the single crystal 17 which was in contact with the bottom cover 3 of the heating furnace, and no crack was generated. As can be seen from this, it is preferable to use a material having the same component as that of the single crystal 17 in the part of the device configuration in contact with the single crystal 17 in the high temperature state. Moreover, sufficient effect can be expected even if only the clear substance which does not react with single crystal 17, such as a platinum foil, is arrange | positioned on the upper part of the bottom cover 3 of a heat insulation furnace.

In the first embodiment of the present invention, only LiTaO ₃ and LiNbO ₃ are mentioned as oxide single crystals, but the above-described effects can also be sufficiently expected for a wide range of other oxide single crystals such as Langasite compounds. In addition, this invention is not limited only to an oxide single crystal. The invention is also effective for other single crystals that tend to cause cracks and require a long time for cooling, and the same effects can be expected such as improvement in production efficiency, reduction in manufacturing cost, and long life of device components.

(2nd 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 plate 11, or the after heater 12, not only the growth furnace 1 but also the heat retention furnace 2 is airtight SUS. The case where crystal lifting is carried out by accommodating the first chamber 35 and preventing the precious metal members 5, 11 and 12 from reaching the atmosphere has been described.

However, since the grown single crystal 17 is an oxide single crystal, there is no big problem even when exposed to the atmosphere. Even if the heat-retaining furnace 2 has a structure that does not contain a substance that is easy to oxidize itself, even if it is exposed to an air atmosphere, there is no big problem. Therefore, the exact tightness is not necessary for the grown single crystal 17 and the heat retention furnace 2. It is only the growth furnace 1 which has precious metal members, such as the precious metal crucible 5 which is easy to be oxidized at high temperature.

Therefore, in the second embodiment of the present invention, a single crystal production apparatus capable of interrupting the growth furnace from the outside air, arranging the growth furnace in the air atmosphere, and allowing continuous crystal lifting with a relatively simple structure will be described.

It is sectional drawing which shows the structure of the single crystal manufacturing apparatus which concerns on 2nd Embodiment of this invention. The single crystal manufacturing apparatus according to the second embodiment accommodates the growing furnace 51 in which the single crystals are grown, the lifting shafts 14 through 16, and the grown single crystals 17, and the insulating furnace 52 in which the single crystals 17 are cooled. ) And at least one gas inlet 73 for introducing an inert gas into the inside of the hermetic container 56.

The growth furnace 51 is provided with at least the precious metal crucible 5 in which the raw material melt 13 was accommodated. The noble metal crucible 5 is made of a noble metal which is easy to oxidize in a high temperature state such as iridium, platinum or platinum rhodium. Here, an iridium crucible with a diameter of 180 mm phi and a height of 150 mm is used. The growth path 51 includes a refractory plate 61 made of a noble metal, an after heater 12, a refractory crucible 6, a refractory thermal insulation tower 7, a refractory thermal insulation tower 7, and a refractory ring 61. It also has a build top top cover 58 disposed on the ring 61. The refractory ring 61 is made of a heat insulating material containing refractory material in the same way as the refractory crucible 6 or the refractory thermal insulation tower 7. The growth furnace upper cover 58 has a hole through which the lifting shaft 15 can pass, and has a structure that can be opened and closed so that the grown single crystal 17 can pass therethrough. The structure of the growth furnace upper cover 58 will be described later with reference to the respective views in FIG. 15. Induction heating coils 10 are arranged on the outer circumference of the precious metal members 5, 11, 12.

The lifting shafts 14 to 16 are formed of a lifting rod 14, an alumina rod 15, and a seed crystal 16. The seed crystal 16 is disposed at one end of the lifting shaft, and the seed crystal 16 is pulled from the liquid level of the raw material melt 13 to grow the single crystal 17 under the seed crystal 16. The load cell 22 is connected to the other end of the lifting shaft.

The heat insulation path 52 is arrange | positioned above the growth path 51, and the opening part for accommodating the single crystal 17 in the growth path 51 is formed in the bottom part. The heat retention path 52 can move in a lifting axis direction and a lifting axis vertical direction. A hole through which the alumina rod 15 can penetrate is formed in the upper part of the heat retention furnace 52. The warming furnace 52 may move in synchronization with the lifting shaft. Moreover, on the hole of the heat-retaining furnace 52, the heat-retaining upper part cover 60 which has a tubule which is close to a hole and through which the lifting shaft (alumina rod) 15 can penetrate is arrange | positioned. The diameter of the tubular tube is thin enough that the alumina rod 15 can penetrate, and is smaller than the diameter of the hole of the heat keeping furnace 52.

The airtight container includes a growth path storage container including a growth path storage container 54 and a base 55 surrounding the side and bottom surfaces of the growth path 51, and a quartz ring 57 on the upper part of the development path storage container 54. At least one airtight opening / closing cover 59 is provided through (). The airtight opening and closing cover 59 has a hole 59c through which the lifting shaft 15 can penetrate, and has a structure that can be opened and closed so that the grown single crystal 17 can pass therethrough. The structure of the airtight opening and closing cover 59 will be described later with reference to the drawings of FIG. 16. In the second embodiment, the growth path storage container is disposed below the cylindrical growth path storage container 54 and the growth path 51 disposed on the outer circumference of the development path 51, and the growth path storage container 54 is provided. It is provided with a base 55 in close contact with the bottom. The growth furnace housing 54 is made of quartz. The base 55 is made of refractory or water-cooled SUS (stainless steel). Induction heating coil 10 is disposed on the outer circumference of the growth furnace housing (54). The upper surface of the airtight opening and closing cover 59 is a flat surface, and the bottom portion of the heat insulating passage 52 is in close contact with the upper portion of the airtight opening and closing cover 59. Of course, in the bottom part of the heat insulation path 52, in order to ensure closeness with the upper surface of the airtight opening and closing cover 59, it has a flat structure.

The gas introduction port 73 is disposed in one portion of the growth passage storage cylinder 54. The gas introduced from the gas inlet 73 is an inert gas such as argon, nitrogen, or krypton.

As described above, the lower part of the growth furnace storage container 54 is in close contact with the base 55, and the airtight opening and closing cover 59 is closely connected to the upper portion of the development furnace storage container 54 through the quartz ring 57. . Moreover, the bottom part of the heat retention path 52 is in close contact with the upper part of the airtight opening / closing cover 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, and introduced into the heat keeping furnace 52 through the hole 59c of the hermetic opening / closing cover 59. It is discharged | emitted to air | atmosphere from the space | interval of the heat retention upper lid 60 and the alumina rod 15. The inside of the airtight container, the airtight opening / closing cover 59 and the heat insulating furnace 52 is kept in a gas tight state, except for the gap between the gas inlet 73 and the heat cover upper cover 60 and the alumina rod 15. It is. Only the inert gas is introduced from the gas inlet 73. On the other hand, since an inert gas is discharged from the space | interval of the heat-cover upper cover 60 and the alumina rod 15, it can hardly prevent outside air from entering from the space | interval. Therefore, the interior of the growth path 51 can be shut off from the atmosphere. In other words, by continuously introducing an inert gas from the gas inlet 73, the internal pressures of the airtight container, the airtight opening and closing cover 59, and the heat retaining furnace 52 are kept higher than atmospheric pressure, and the heat retaining furnace upper cover 60 is provided. The air can be prevented from flowing out from the interval between the alumina rod and the alumina rod 15.

FIG. 15 is a plan view showing the configuration of the growth furnace upper cover 58, and shows the planar shape of the growth furnace upper cover 58 when viewed from the lifting axis direction. FIG. 15A illustrates a state in which the growth furnace upper cover 58 is closed, and FIG. 15B illustrates a state in which the growth furnace upper cover 58 is opened. As shown in Fig. 15A, the growth path upper cover 58 is in a direction perpendicular to the sliding direction of the pair of retractable blades 58b and the retractable blades 58b, which are slidable in a direction perpendicular to the lifting axis. It has a pair of stationary blades 58a arranged at predetermined intervals. The growth furnace top cover 58 achieves the role of creating the furnace temperature environment suitable for crystal growth. Four blades 58a, 58b are disposed on the refractory ring 61.

An arc-shaped fixed blade 58a disposed along the inner circumference of the growth passage accommodating cylinder 54 is in close contact with the refractory ring 61. The open / close blades 58b disposed between the pair of fixed blades 58a block the inner circumference of the refractory ring 61 (circles indicated by the point islands in FIG. 15A). In the center of the fitting portion of the pair of opening and closing blades 58b, holes 58c are formed so that the alumina rod 15 can penetrate. The retractable blade 58b has a semicircular cutout at a substantially center portion of the straight portions facing each other. The semicircular incision forms a circular hole 58c through which the alumina rod 15 penetrates in the center of the upper cover 58 when the upper cover 58 is closed and the two openable blades 58b are combined. Done.

As shown in FIG. 15 (b), the inner circumference of the refractory ring 61 is indicated by a solid line in the refractory ring 61 by sliding a pair of the retractable blades 58b from side to side on the refractory ring 61. Circle) is opened. The opening of the refractory ring 61 is large enough to allow the grown single crystal to pass through.

FIG. 16: is a top view which shows the structure of the airtight opening and closing cover 59, and shows the planar shape of the airtight opening and closing cover 59 when seen from the lifting axial direction. FIG. 16A shows a state where the airtight opening and closing cover 59 is closed, and FIG. 16B shows a state where the airtight opening and closing cover 59 is open. As shown in Fig. 16A, the airtight opening / closing cover 59 has a pair of retractable blades 59b and retractable blades 59b which can slide in a direction perpendicular to the lifting shaft in the same way as the upper cover 58 of the growth path. Has a pair of fixed blades (59a) arranged at predetermined intervals in the direction perpendicular to the slide direction. Four blades 59a and 59b are disposed on the quartz ring 57.

The arc-shaped fixed blade 59a is in close contact with the quartz ring 57. The retractable blade 59b disposed between the pair of fixed blades 59a blocks the inner circumference of the quartz ring 57 (circles shown by dotted lines in Fig. 16A). In the center of the fitting portion of the pair of openable blades 59b, a hole 59c is formed so that the alumina rod 15 can penetrate. The retractable blade 59b has a semicircular cutout at a substantially central portion of the straight portions facing each other. The semicircular incision cuts a circular hole 59c through which the alumina rod 15 penetrates the center of the airtight opening and closing cover 59 when the airtight opening and closing cover 59 is closed and the two opening and closing blades 59b are combined. To form.

As shown in FIG. 16B, the pair of open and close blades 59b are slid left and right over the quartz ring 57 so that the inner circumference of the quartz ring 57 is solid (in FIG. 16B). Circle shown) is opened. The opening of the quartz ring 57 is large enough to allow the grown single crystal to pass through.

(Single crystal production method)

Next, the manufacturing method of the single crystal using the single crystal manufacturing apparatus shown in FIG. 11 is demonstrated with reference to FIGS. 11 to 14 are device cross-sectional views showing the 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, a sintered material having a weight of 10 kg weighed by sintering Li ₂ CO ₃ and Ta ₂ O ₅ so as to have a composition ratio of Li / Ta = 0.943 (molar ratio) is fed into the precious metal crucible 5. The power applied to the induction heating coil 10 is increased to heat the precious metal members 5, 11, 12 in the growth furnace 1 and form a raw material melt 13 having a weight of 15 kg. Then, the power applied to the induction heating coil 10 is controlled, and the temperature of the liquid level of the raw material melt 13 is adjusted to a temperature suitable for growing single crystals.

In addition, the process of melting a sintering material to form the raw material melt 13, and adjusting a temperature to the temperature suitable for growth of a single crystal is called "in-house temperature rising process." In the furnace temperature raising process, the growth furnace upper cover 58 shown in FIG. 15 and the airtight opening / closing cover 59 shown in FIG. 16 are in a closed state. The temperature distribution in the growth furnace 51 is smoothed to form a temperature distribution suitable for growing single crystals. Moreover, the bottom part of the heat retention path 52 is close to the upper part of the airtight opening / closing cover 59, and the inert gas is continuously introduced from the gas introduction port 73. As shown in FIG.

(B) Next, the lifting shafts 14 to 16 are moved toward the raw material melt 13 so that the seed crystal 16 at the tip of the lifting shaft is brought into contact with the liquid level of the raw material melt 13. As shown in Fig. 11, the lifting shafts 14 to 16 are pulled up while being rotated to form single crystals 17 below the seed crystals 16. After the single crystal 17 is grown to a predetermined length, the single crystal 17 is cut off at the liquid level. The cutting of the single crystal 17 may be performed by lifting the lifting shafts 14 to 16 to a predetermined distance at a high speed of 10 to 100 mm / min. In addition, a method of forming a crystal tail at the lower end of the single crystal 17 and cutting it off from the liquid surface may be used. In this way, a lithium tantalate (LiTaO ₃ ) single crystal 17 having a linear diameter of 105 to 110 mmφ and a weight of 6 to 7 kg is grown.

The process from the above contact of the seed crystal 16 to the liquid level to the cutting off of the single crystal 17 at the liquid level is referred to as a "single crystal growth process". Also in the single crystal growth process, the growth path upper cover 58 and the airtight opening and closing cover 59 are in a closed state. Moreover, the bottom part of the heat retention path 52 is close to the upper part of the airtight opening / closing cover 59, and the inert gas is continuously introduced from the gas introduction port 73. As shown in FIG.

(C) Next, preparation for moving the grown single crystal 17 from the growth furnace 51 to the heat retention furnace 52 is performed as shown in FIG. First, the temperature in the heat retention furnace 52 is set to the predetermined temperature required for accommodating the single crystal 17 in a high temperature state immediately after being grown. Also in the second embodiment, preparation for moving the grown single crystal 17 from the growth furnace 51 to the heat retention furnace 52 is performed after the single crystal growth step, but of course, the single crystal 17 is grown. You may carry out in the meantime. Next, the retractable blade 58b of the upper cover 8 of the growth path shown in FIG. 15 is opened left and right, and the retractable blade 59b of the airtight opening and closing cover 59 shown in FIG. 16 is opened left and right.

(D) Next, the single crystal 17 is moved from the growth furnace 51 to the heat retention furnace 52 at a predetermined speed, and the single crystal 17 is stored in the heat retention furnace 2. Then, the closing blade 58b of the growth furnace upper cover 58 is closed, and the closing blade 59b of the airtight opening and closing cover 59 is closed. In the preparation process for moving the single crystal 17, the process of storing the single crystal 17 in the heat retaining furnace 52 and covering the lids 58 and 59 is referred to as "crystal heat retaining process". Even in the step of accommodating the crystal insulated furnace, the bottom of the insulated furnace 52 is in close contact with the upper part of the airtight opening and closing cover 59, and the inert gas is continuously introduced from the gas inlet 73.

In the second embodiment, the distance in the lifting axis direction between the growth furnace upper lid 58 and the airtight opening / closing lid 59 is made as short as possible in consideration of the crystal lathe storage step. When the single crystal 17 passes through the growth furnace top cover 58 and the airtight opening and closing cover 59, the slope is four blades 58a and 58b made of refractories of the growth furnace top cover 58 and the airtightness. It is surrounded by the four blades 59a and 59b made of quartz which the opening and closing cover 59 has, and the bottom part of the heat insulation path 52 is in close contact with the upper part of the airtight opening and closing cover 59. Therefore, there is little place for heat to run off in the vertical direction of the lifting axis. Therefore, the single crystal 17 is accommodated in the heat retention path 52 without being cooled.

(E) Next, the single crystal 17, the lifting shafts 14 to 16, and the heat retaining furnace 52 are synchronized (moving) in the lifting axis direction. Then, as shown in FIG. 13, the bottom cover 53 is attached to the bottom of the heat retaining furnace 52. At this time, the flow rate of the inert gas introduced from the gas introduction port 73 is increased to prevent air from entering the airtight container from the hole 59c of the airtight opening and closing cover 59. Specifically, after the single crystal 17, the lifting shafts 14 to 16 and the heat retaining furnace 52 are moved (rising) until the bottom of the heat retaining furnace 52 is above the heat retaining bottom cover 53, the heat retaining furnace The bottom cover 53 is moved in the vertical direction of the lifting shaft to be mounted on the bottom of the heat insulating furnace 52. Thereafter, the thermal insulation chamber 52 and the thermal insulation bottom cover 53 are connected. Then, the single crystal 17 is landed on the bottom cover 53 of the heating furnace, and the alumina rod 15 is cut off from the lifting rod. The single crystal 17, the lifting shaft 15. 16, the heat retaining furnace 52, and the heat retaining bottom cover 53 are moved in the vertical direction of the lifting shaft. At the same time, the power to the induction heating coil 10 is increased to increase the temperature of the precious metal crucible 5. Further, in order to prevent air from entering the hermetic container from the hole 59c of the hermetic opening / closing cover 59, the hole 59c of the hermetic opening / closing cover 59 immediately after the movement (rising) of the heat insulating furnace 52. May be covered with a plate having a heat resistance and heat shock resistance. In addition, cooling of the single crystal 17 after lifting takes about one day (24 hours) or longer.

(F) Next, the single crystal 17 is cooled in the heat storage 52, and a single crystal raw material (sintered raw material) 21 consumed by the growth of the single crystal 17 is noble metal crucible (5). Please replenish. The raw material supply device has a raw material supply container 69 for accommodating the sintered raw material 21 and a raw material supply pipe 70 that can be disposed substantially parallel to the lifting axis direction at the center of the precious metal crucible 5. One end of the raw material supply pipe 70 is disposed very close to the liquid level of the raw material melt 13, and the raw material supply pipe 70 is a hole 58c of the upper cover 58 and the airtight opening and closing cover 59 for the growth path in a closed state. Penetrates through the hole 59c. From the other end, the sintered raw material 21 is supplied into the crucible 5 at a predetermined feed rate.

Since the weight of the raw material melt 13 consumed by the growth of the single crystal 17 is the weight of the single crystal 17 measured by the load cell, the same amount of sintered raw material 21 as the single crystal 17 is supplied. And the raw material melt 13 whose gross weight is 15 kg is formed. At this time, the sintered raw material 21 is replenished while rotating the noble metal crucible 5 (while rotating the supporting rod). Since the heat insulation path 52 is movable in a lifting axis (up-down) direction and a lifting axis vertical (left-right) direction, workability is quite good. Further, since the raw material supply pipe 70 is arranged in the lifting axis (up and down) direction, the sintered raw material 21 is not blocked 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 part of the new heat insulation furnace 52b in which the heat insulation furnace top cover 60 was mounted is made close to the upper part of the airtight opening / closing cover 59. As shown in FIG. Pass the alumina rod 15 and the seed crystal 16 through the tubules of the upper cover 60 of the heating furnace, the airtight opening and closing cover 59 in the closed state, and the holes 58c and 59c of the upper cover 58 of the growth furnace. The tip of the seed crystal 16 extends to the liquid level of the raw material melt 13, and the next crystal growth is performed. Oxide single crystals are generally prone to cracking and require long time around 10 hours or more for cooling after lifting. However, most of this long time cooling is performed in the heat retention furnace 52a arrange | positioned outside the airtight container. The workability is considerably improved since the removal of the heat retainer 52a and the installation of a new heat retainer 52b, the installation and removal of the raw material supply pipe 70, and the resetting of the seed crystal 16 are not restricted in space. .

Although repeating the above procedure, 10 crystals were lifted in succession, no problems such as cracking occurred in all single crystals, and no clogging of the raw material supply pipe 70 occurred. In addition, there was almost no deterioration of the refractory in the growth furnace.

As described above, according to the second embodiment of the present invention, not only has the effect of "improving the productivity of the apparatus and reducing the production cost as the life of the refractory and the precious metal member becomes longer" described in the first embodiment, It also has other effect shown below. In other words

(1) Since only the growth path 51 is accommodated in the hermetic container, the hermetic container itself can be made small.

(2) In the " inner furnace temperature raising step ", " single crystal growing step " and " crystal insulation furnace accommodating step " Oxidation of the noble metal member disposed in the growth furnace 51 can be prevented.

(3) It is unnecessary to replace the heat keeping furnace 52a in which the single crystal 17 which needs to be cooled slowly and the empty heat keeping furnace 52b for accommodating the next single crystal in the hermetic chamber is not necessary. An apparatus (hanging means 25, etc.) becomes unnecessary.

(4) Since the supply of the sintered raw material 21 is carried out using the raw material supply pipe 70 vertically disposed directly above the precious metal crucible 5 without carrying out from the outside of the large airtight chamber (see FIG. 4). The distance between the supply container 69 and the precious metal crucible 5 does not fall, and the sintered raw material 21 does not become blocked in the middle of the pipe 70.

As mentioned above, although this invention was described by the 1st and 2nd embodiment and the 1st-5th experiment example, the description and drawings which form a part of this indication are not to be understood as limiting this invention. Those skilled in the art will recognize various alternative embodiments, examples and operational techniques from this disclosure.

In the embodiment, although lithium tantalate (LiTaO ₃ ), which is a typical oxide single crystal, has been described, the same effect can be expected for a wide range of other oxide single crystals such as lithium niobate (LiNbO ₃ ) or langasite compounds. Furthermore, the present invention is not limited to an oxide single crystal, and a noble metal member such as a crucible disposed in a manufacturing apparatus to be used is likely to be oxidized at a high temperature, or a crack is likely to occur in the lifting crystal. It is possible to improve the substantial drive ratio of the apparatus for producing the single crystal also for other single crystals requiring ().

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

Moreover, according to this invention, the single crystal manufacturing apparatus and single crystal manufacturing method with high single crystal production efficiency can be provided.

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

According to the present invention, it is possible to provide a single crystal production apparatus and a single crystal production method capable of simultaneously cooling single crystals and growing the next single crystal.

Claims (22)

delete delete delete delete delete delete delete A first step of melting a raw material of the single crystal contained in a noble metal crucible disposed inside a growing furnace in which the single crystal is grown, to form a raw material melt, A second step of bringing the seed crystal disposed at the tip of the lifting shaft into contact with the liquid level of the raw material melt; A third step of raising the lifting shaft to grow a single crystal under the seed crystal, A fourth step of cutting off the single crystal from the liquid surface after the single crystal reaches a predetermined length, A fifth step of moving the single crystal from the growth furnace to the warming furnace at a predetermined speed and storing the single crystal in the warming furnace, A sixth step of synchronously moving said single crystal, said lifting shaft and said heat retaining path with respect to said lifting shaft; A seventh step of cooling the single crystal in the heat retention furnace, and And a eighth step of replenishing the raw material of the single crystal in the noble metal crucible. The method of claim 8, The third step is disposed on the growth path, and is carried out in a state where the opening and closing free growth path upper cover having a hole through which the lifting shaft penetrates is closed, And a step of opening the upper cover of the growth path between the fourth step and the fifth step. The method of claim 9, And the distance from the bottom of said heat retaining furnace to the top of said growth furnace upper cover in said fifth step is 20 mm or less. The method of claim 10, The bottom part of the said heat insulation furnace in the said 5th step is in close contact with the upper part of the said growth furnace upper cover. The method of claim 8, In the fifth step, the center temperature of the heating furnace is set to a temperature of 0.7 to 1 times the melting point (absolute temperature) of the single crystal, And the predetermined speed in an area where the temperature on the lifting shaft from the growth furnace to the heat retention furnace is smaller than the temperature of the center of the heat retention furnace is faster than the predetermined speed in other areas. The method of claim 8, And the predetermined speed until the lifting axial temperature distribution near the central portion of the single crystal reaches a point near the center temperature of the heating furnace in the fifth step is 5 mm or less per minute. The method of claim 8, And a center of the single crystal accommodated in the heat keeping furnace in the fifth step is located above the center of the heat keeping furnace. The method of claim 8, A step of attaching a bottom cover of the heat insulating furnace in which powder of the same component as the single crystal is placed on the top of the bottom of the heat holding furnace between the fifth step and the seventh step; And a step of landing the single crystal on the bottom cover of the thermal insulation furnace. A growth furnace having a precious metal crucible in which the raw material melt is accommodated, and wherein single crystals are grown; A lifting shaft disposed at the tip of the seed crystal, for lifting the seed crystal from the liquid level of the raw material melt to grow the single crystal under the seed crystal; An insulation furnace formed with a hole through which the lifting shaft penetrates, and which can move together with the lifting shaft in a direction parallel and perpendicular to the lifting shaft, and accommodates the grown single crystal to cool the single crystal; The growth path including a growth path storage container surrounding side and bottom surfaces of the growth path, and an airtight opening / closing cover which is close to an upper portion of the growth path storage container and has a hole through which the lifting shaft passes. Airtight containers to block from the outside air; And A gas inlet for introducing an inert gas into the hermetic container, Single crystal manufacturing apparatus characterized in that the bottom portion of the heat insulating furnace can be in close contact with the upper portion of the airtight opening and closing cover. The method of claim 16, A single crystal manufacturing apparatus, further comprising: an upper cover of the heat insulating furnace, the upper cover of which closes the hole formed in the upper portion of the heat insulating furnace, and has a tubule that can pass through the lifting shaft. The method of claim 16, The airtight opening and closing cover includes a pair of retractable blades slidable in a direction perpendicular to the lifting shaft, and a fixed blade disposed at predetermined intervals in a direction perpendicular to the sliding direction of the retractable blade. Single crystal manufacturing device. The method of claim 16, The growth path is disposed above the refractory crucible, characterized in that the single crystal manufacturing apparatus further comprises a free-opening growth top cover having a hole through which the lifting shaft passes. The method of claim 19, The growth path upper cover includes a pair of retractable blades slidable in a direction perpendicular to the lifting axis, and a fixed blade disposed at predetermined intervals in a direction perpendicular to the slide direction of the retractable blade. Single crystal manufacturing device. The method of claim 16, And a raw material supply device for supplying the raw material of the single crystal into the precious metal crucible, the function of adjusting the supply speed of the single crystal raw material. The method of claim 21, And the raw material supply device supplies the single crystal raw material through a tube disposed on a substantially central axis of the growth furnace.