JP2010241646A - Single crystal pulling device - Google Patents

Abstract

A pulling apparatus capable of simultaneously growing a plurality of single crystals is provided.
A plurality of pulling-down crucibles 11 equally distributed around a predetermined central axis, and a plurality of heating coil parts 17a, 17b, 17c around which each of the crucibles 11 is wound, and a heating coil part 17a , 17b, 17c are connected in series so that current flows in the same direction with respect to the axis of each of the coil portions 17a, 17b, 17c, and a plurality of heating coil portions 17a, 17b, Power is applied to the circuit having 17c.
[Selection] Figure 1

Description

  The present invention relates to an apparatus for producing single crystals such as oxides, fluorides, and metal alloys used for so-called laser optical elements, nonlinear optical elements, medical scintillators, piezoelectric elements, giant magnetostrictive elements, and the like. More specifically, a pulling method for obtaining a desired crystal material while drawing a raw material melt from a hole provided at the lower end of the crucible, particularly a so-called micro pulling (μ-pD) method for obtaining a fiber-like single crystal. The present invention relates to a single crystal pulling apparatus that can cope with a crystal manufacturing method and simultaneously pull down a plurality of single crystals.

  A pull-out hole is formed in the lower end of the crucible holding the heated and melted raw material, crystal nuclei (hereinafter referred to as seeds) are brought into contact with the raw material melt leaked from the hole, and leakage of the raw material from the hole is caused. A so-called reduction method is known in which a single crystal that grows with the seed as a nucleus is obtained by lowering the seed. A single crystal obtained by this method has a smaller crystal diameter than that of a single crystal obtained by a so-called pulling method represented by a conventionally known CZ method. However, as a method for obtaining a single crystal having a short time required for crystal growth and excellent in crystallinity at a low cost as compared with the CZ method, it is necessary to modify the actual manufacturing equipment in terms of hardware and various single units. Application to crystals has been studied.

  In the pulling method, there is the above-described so-called micro pulling method (see Patent Document 1) as a method for obtaining a fiber crystal having higher crystallinity and maintaining a high crystal growth rate. Using this method, production conditions for oxide single crystals such as alumina and calcia have been studied. In the single crystal pulling device disclosed in Patent Document 1, high frequency power is applied to a coil wound around the crucible, and the heating element or the crucible body disposed between the crucible and the coil is heated by the high frequency power, The raw material melt inside the crucible is dissolved. Also, a cylindrical so-called after-heater made of a conductive material is disposed at the lower part of the crucible, and by controlling the magnitude of the temperature gradient in the raw material melt that is pulled down from the crucible by causing the after-heater to generate heat, Crystal growth conditions are obtained.

JP 2006-347789 A

  In the above-described micro-pulling-down method, a rod-shaped single crystal is generally manufactured using various materials. However, in the actual manufacturing process, filling the crucible with raw materials, attaching the crucible to the device, exhausting the inside of the device and introducing a predetermined gas as needed, heating and melting the raw material, seed for the raw material melt leaking from the crucible The following operations are carried out in sequence: proper contact of the substrate, pulling down of the seed at an appropriate speed, slow cooling of the obtained single crystal and the device, opening of the device and removal of the single crystal. In consideration of the development of the obtained single crystal on a commercial basis, it is also required to shorten these process times. In particular, in the case where the crystal must be grown in a specific atmosphere such as an inert gas or an oxidizing gas, the time required to open and close the so-called chamber for housing the crucible and the coil is large. Time reduction is required.

  The present invention has been made in view of the above situation, and by arranging a plurality of crucibles in a single chamber, it is possible to grow a plurality of single crystals substantially simultaneously, and an operator of a manufacturing apparatus. It is an object of the present invention to provide a single crystal pulling apparatus that can grow and produce a single crystal that is suitable and stable.

  In order to solve the above problems, a single crystal pulling device according to the present invention has a cylindrical shape that becomes a closed portion with a closed bottom portion, and has a through hole that penetrates the closed portion from the inside of the cylindrical shape to the outside. The raw material melt held in the crucible is leaked from the through hole, and the seed that determines the crystal orientation when the raw material melt is crystallized is brought into contact with the leaked raw material melt, and the seed is used as a predetermined pulling shaft. The present invention relates to a single crystal pulling apparatus that obtains a single crystal that grows with a seed as a base point by pulling down along a plurality of crucibles that are equally distributed around a predetermined central axis, and each crucible coaxially with the crucible. A plurality of heating coil sections arranged in a wound manner, the plurality of heating coil sections being connected in series, and power is supplied from a single introduction end to the plurality of heating coil sections. It is characterized by

Regarding the above-described pulling-down device, the coil axes that are the central axes of the plurality of heating coil parts are parallel to each other, and the flow direction of the current flowing through the heating coil parts is the same when the coil axis is used as a reference. It is preferable that the winding direction of the coil in the plurality of heating coil portions is determined. Alternatively, the plurality of heating coil portions may be configured to be wound so that the directions of the magnetic fields formed by each of the heating coil portions are parallel and in the same direction. In addition, the plurality of heating coil portions have a predetermined center so that the coil axes do not overlap even when the coil axis that is the central axis of the heating coil portion is moved around the predetermined central axis. It is more preferable that the respective heating coil portions are arranged to be shifted in the axial direction. Further, the plurality of heating coil portions have a heating coil portion made of a coil in which at least one of the number of turns of the coil, the winding diameter, the winding interval, and the coil length is different from that of the other coil portions. Is more preferable. Furthermore, the pulling device further includes a chamber that has a heating coil part and a crucible inside to form a sealed space, and an imaging means that can observe the lower part of the crucible,
The chamber has a plurality of observation windows on the wall surface of the chamber closest to each crucible so that the imaging means can observe the lower part from the outside of the chamber.

  In the present invention, it is possible to arrange a plurality of crucibles in a single chamber and simultaneously pull down the single crystal from these crucibles. Moreover, all the heating coil parts which heat-generate a crucible are connected in series, and the heating mechanism is comprised as an integrated circuit. According to the present invention, since only a single high-frequency power introduction unit is required for the chamber, the configuration related to the application of high-frequency power, such as a so-called high-frequency power supply, power supply introduction end, and high-frequency coil, is simplified, and the apparatus configuration Can be obtained, and the cost required for constructing the apparatus can be reduced. In addition, because of this configuration, unlike the case where high frequency power is applied from different power sources from a plurality of introduction units, it is easy to cope with the interaction of high frequency power introduced from each power source, so-called matching operation, Power supply control when applying high-frequency power becomes easy. Further, since the axes of the high-frequency coils are arranged so as to be equidistant with respect to a specific (predetermined) central axis, the high-frequency coils also interact with each other and the chamber wall that contains them And the like, and the heating conditions of each crucible can be equalized.

  Further, according to the present invention, the winding direction of each heating coil is all the same with respect to the axial direction (the extending direction of the coil axis that is the central axis when the central axis of the coil is used as a reference), The flow direction of the current flowing through the heating coil is the same. As a result, the directions of the induction magnetic fields formed when the high frequency power is applied to each heating coil are all the same, and heating under the condition that the influence of self induction is constant is possible. Further, in the present invention, the heating coils in the vertical direction are arranged with a so-called step by sequentially shifting upward or downward. This makes it possible to minimize the length of a portion that exists as a wiring that does not affect the heating that exists between the heating coils, thereby minimizing current loss. For example, when adopting an apparatus configuration for increasing productivity such as an increase in the length of the crucible or an increase in the number of crucibles, the reduction of the portion that causes such a current loss greatly suppresses the load on the power source. It will be. Further, by arranging the stepped portions, the arrangement of the solid-liquid boundary portion (meniscus) that becomes a boundary where the raw material melt formed in the crucible lower part is crystallized is also shifted in the vertical direction. . Therefore, when observing the meniscus with a CCD or the like, it is possible to reliably capture individual meniscus without causing overlapping on the image.

It is a figure which shows the state which looked at the structure of the principal part from the upper direction regarding the pulling-down apparatus of the single crystal which concerns on one Embodiment of this invention. It is a figure which shows the state which looked at the principal part structure of the pulling-down apparatus of the single crystal shown in FIG. 1 from the side. FIG. 3 is an explanatory diagram in which only a crucible and a heating coil are extracted from the configuration group illustrated in FIG. 2. It is a figure which shows typically the state which looked at the structure relevant to the crucible simple substance from the side regarding the pulling-down apparatus of the single crystal shown in FIG.

  An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an outline of main components of a single crystal pulling apparatus according to an embodiment of the present invention as viewed from above. 2 is a diagram showing an outline when the configuration shown in FIG. 1 is viewed from the side. Further, FIG. 3 is a diagram showing only the crucible and the heating coil extracted from the configuration shown in FIG. In the present embodiment, three heating coil portions connected in series are formed from one high-frequency transmission wiring connected to one high-frequency power source. A crucible is arranged inside each heating coil section so that the axis of the coil axis, which is the central axis of the heating coil section, coincides with the axis. Therefore, since each heating coil part and the related structure are the same, it does this paying attention to a single heating coil part regarding the detailed description of these related structures. Further, common configurations will be described using the same reference numerals. FIG. 4 is a so-called partial enlargement schematically showing a related configuration of the crucible alone shown in FIG. 1 and the like and one of the heating coil portions (first heating coil portion) provided thereto as viewed from the side. It is a figure equivalent to a figure. Before describing the embodiment of the present invention, first, a structure associated with a single crucible, that is, a first crystal growth unit among the first to third will be described below with reference to FIG.

  The crystal growth unit 3 (first crystal growth unit) includes, as main components, a seed 5, a crucible 11, an after heater 13, a heating coil 17 (first heating coil portion 17a), a crucible stage 19, an outer tube 25, A seed holder 31 and a seed drive mechanism 33 are provided. Further, as a configuration shared by the first to third crystal growth units 3, a CCD camera 35 and a control device 39 are provided. The first heating coil portion 17a (and other second and third heating coil portions) heats the raw material (in this embodiment, the main heated material is not the raw material crucible 11) and melts the raw material by high-frequency induction. ing. The high-frequency power is transmitted from the high-frequency power source to the object to be heated and the like through the first heating coil portion 17a in which a metal tube capable of conducting cooling water or the like is formed in a coil shape having a predetermined inner diameter. Is done. The crucible 11 in which the raw material is held and melted has a cylindrical shape with a closed bottom surface (lower end surface), and is made of carbon or a refractory metal (for example, Re, Ir, W, Ta, Mo, Pt, or These alloys). At the center of the bottom surface of the crucible 11, a through hole is provided along the central axis of the crucible so as to penetrate the bottom surface, which is a closed portion of the cylinder, from the inside of the crucible 11 to the outside. The raw material held inside the crucible 11 is melted mainly by the heat generated by the crucible 11, and the raw material melt generated by melting inside the crucible 11 leaks out below the crucible through the through hole. The crucible 11 is coaxial with the coil axis, which is the central axis of the first heating coil portion 17a, and is disposed at the central portion in the longitudinal direction of the first heating coil portion 17a. That is, the heating coil portions 17a are arranged so as to wind the crucible 11.

  When the crystallization of the raw material melt progresses in contact with the raw material melt, the seed 5 has a function of forming a crystal orientation and determining a crystal orientation. The seed 5 is supported by a seed holder 31 that extends along the central axis of the crucible 11 and can move up and down along the central axis, and is disposed vertically below the through hole. The leaked raw material melt comes into contact with the seed 5 to start crystallization, and the seed 5 is pulled down along the above-mentioned central axis to promote crystal growth and growth. Below the crucible 11, a cylindrical after-heater 13 that contacts the vicinity of the outer periphery of the lower end of the crucible 11 and supports the crucible 11 is disposed. The after heater 13 is made of the same material as that of the crucible and is arranged so as to be coaxial with the crucible 11. When the raw material is heated, the after-heater 13 also generates heat by high-frequency induction, and the raw material melt that leaks from the lower end of the crucible 11 can be heated. Further, the length of the after-heater 13 is set so that the crucible 11 disposed at the center portion in the longitudinal direction of the first heating coil portion 17a and the after-heater 13 are placed in contact with each other. The after-heater 13 is set to be accommodated in the effective heating area in the portion 17a. By installing the after heater 13, the soaking area in the pulling-down direction can be expanded, and the conditions for crystal growth can be made wider.

  In the present embodiment, the after heater 13 is supported by the upper surface of the annular crucible stage 19 at the lower end thereof. The crucible stage 19 is made of a material having insulation properties against high-frequency induction used for heating, such as ceramics and quartz. The crucible stage 19 is supported on the lower surface by an upper end portion of a cylindrical outer tube 25 made of the same material as the crucible stage 29. The crucible 11, the after heater 13, the crucible stage 19 and the outer tube 25 are arranged so as to be coaxial, and the crystal pulling operation is performed along the axis. The seed 5 is held by the upper end portion of the seed holder 31, and the rod-like seed holder 31 is connected to the seed drive mechanism 33 at the lower end thereof. The seed 5 is movable up and down in accordance with the vertical movement of the seed holder 31 in the axial direction by the seed drive mechanism 33. The CCD camera 35 is used for observing the state of meniscus formation. The after-heater 13 is provided with a through-window 13a for meniscus observation, and the CCD camera 35 can capture an image of the meniscus formation region through the through-window. The image obtained from the CCD camera 35 is transmitted to the control device 39, the state of the meniscus is determined based on the obtained image, and the pulling-down speed of the seed 5 is controlled according to the determination result. That is, the seed drive device 33 is controlled in accordance with the meniscus image, and operations such as deceleration of the ascending operation of the seed 5, stop or change to descending, and adjustment of the descending speed are performed.

  The configuration described in the crystal growth unit 3 described above is an example, and various modifications can be made depending on the raw material, for example. Specifically, a cylindrical member made of a conductive material that becomes a further heating element may be disposed between the crucible 11 and the first heating coil portion 17a. The crucible 11 itself may not be configured to generate heat, and the cylindrical member may be configured to generate heat. Alternatively, the structure may be such that the after heater is eliminated, the after heater has a double structure, or the positional relationship between the after heater and the first heating coil portion 17a can be modified. . Further, the form of the crucible 11, in particular, the form of the through hole at the lower end is not limited to the exemplified form, and the shape of the cross section perpendicular to the axial direction of the single crystal to be sought, such as generation of protrusions, multiple through holes, Various modifications can be made accordingly. In addition, although the seed drive device 33 and the control device 39 are shared by all crystal growth units, they may be arranged independently for each crystal unit. In this case, the apparatus configuration is complicated and the productivity may be reduced. However, it is possible to modify the pulling conditions more finely according to the aspect of the meniscus, and a higher quality single crystal is stable. May be obtained.

  Next, with reference to FIGS. 1-3, the specific characteristic of the pulling-down apparatus which concerns on one Embodiment of this invention is demonstrated. The pulling device 1 according to the present embodiment has three crystal growth units 3 described above. As for the heating coil 17, a first heating coil portion 17a, a second heating coil 17b, and a third heating coil 17c are formed as a single body from a single coil material (for example, a copper tube or the like). These heating coil portions are arranged so that the winding directions are all the same with respect to the coil axial direction, and the heating coil portions are connected in series. The pulling device 1 has a cylindrical chamber 4 whose upper and lower portions are closed, and the crystal growth unit 3 is all installed inside the chamber 4. The chamber 4 is accompanied by an exhaust system and a gas introduction system (not shown), and the internal space is exhausted to a so-called vacuum state, or a predetermined pressure is applied with a specific inert gas, fluorinated gas, oxidizing gas, or the like. It can be maintained. The heating coil 17 is connected to the high-frequency introduction end 21 and is connected to a high-frequency power source (not shown) disposed outside the chamber 4 via the high-frequency introduction end 21. In the present invention, since each heating coil part is connected in series, by providing only one high-frequency introduction end 21 for the chamber 4, high-frequency power can be applied to all these heating coil parts. Possible

  The first to third crystal growth units 3 are installed equally around the central axis of the cylindrical chamber 4. Accordingly, the positional relationship between the crystal growth units 3 and the positional relationship between each crystal growth unit 3 and the inner wall of the chamber 4 are all the same. In general, when high-frequency power is applied to a coil and a member disposed inside the coil generates heat by induction current, the power consumed by the object to be heated takes into account various current losses that occur when high-frequency power is applied. Then, it becomes a very small value in practice. More specifically, there are a loss at the connection portion that occurs in the vicinity of the introduction terminal of the high-frequency power, a loss due to various configurations required for coil cooling, a loss caused by the interaction between the plurality of coils, and the like. As in the present invention, each of the heating coil portions is integrated with a single wiring, and power is supplied to the coil portions collectively from a single power source, thereby reducing these various losses. . In addition, since the power consumed by the object to be heated is actually smaller than the total supply power, even if multiple crucibles are targeted, the power consumption actually reduced can be reduced. The loss power to be increased increases, and by using a single coil configuration, effective heating with a smaller power source becomes possible.

  In addition, as shown in FIG. 2, in this embodiment, the heating coil having a sufficient length is left with a coil portion having a predetermined length, and the coil is partially wound in a plane perpendicular to the central axis of the coil. A plurality of coil portions are obtained in a manner that is extended in a continuous manner. More specifically, the upper end of the winding portion of the first heating coil portion 17a and the lower end portion of the winding portion of the second heating coil portion 17b start from the same height in the central axis direction of the coil, and the second heating coil Each heating coil part is connected in series in such a manner that the lower end part of the winding part of the third heating coil part 17c starts from the same height as the upper end part of the winding part of the part 17b. That is, as shown in FIG. 2 or FIG. 3, the heating coil portions and the crucible are sequentially shifted in the axial direction along the length of each heating coil portion. As a result, even when the coil axis that is the central axis of the heating coil portion is moved around the predetermined central axis that is the central axis of the chamber 4, the coil axes do not overlap each other. The heating coil portions are arranged so as to be shifted in the extending direction of the predetermined central axis. Therefore, the structures associated with the individual crucibles 11 such as the seed holder 31 and the seed drive mechanism 33 are arranged as clearly shown in FIG. 3 in consideration of the steps caused by the coil length. A region connecting the coil portions exists only for conducting a high-frequency current, and does not contribute to heating the crucible 11 or the like. However, high-frequency radiation is also emitted from the region, and power loss corresponding to the radiation occurs. As in this embodiment, each heating coil portion is provided with a step corresponding to the length of the heating coil portion so as to be sequentially shifted in the axial direction, and thus exists to simply connect the respective coil portions. It is possible to minimize the area. As a result, for example, even when the high-frequency current to be applied to the individual coils becomes large, it is possible to suppress the loss and effectively heat the raw material.

  In the present embodiment, the meniscus in each crystal growth unit 3 is imaged by a single CCD camera 35. Therefore, the CCD camera 35 is slidably supported on the camera support rail 41 by the annular camera support rail 41 disposed on the outer periphery of the chamber 4. In the chamber 4, a viewing window 4 a is provided on the wall of the chamber 4 closest to the meniscus generating portion so that the meniscus generated in the lower part of the crucible 11 disposed inside can be observed. The CCD camera 35 is supported via a support table 41a so as to be movable relative to the camera support rail 41. The support table 41a is accompanied by a camera swing mechanism 41b composed of a known motor or the like, and the CCD camera 35 can swing within a plane extending in the vertical direction around the swing shaft 41c. It is said. Accordingly, the CCD camera 35 is moved on the camera support rail 41 by a driving mechanism composed of a known motor or the like, stopped at a position where the nearest meniscus can be observed through the observation window 4a, and a camera swing mechanism. The photographing optical axis is leveled by 41b, and the image of the meniscus is acquired. In addition, since each meniscus is formed so as to have a step in the axial direction, the camera support rail 41 is installed so as to have an inclination corresponding to the step of each heating coil portion. Note that a motor (not shown) that drives the CCD camera 35, the camera mechanism 41b, and the like are connected to the control device 39 described above, and sequentially according to a meniscus image discrimination end signal in the control device 38. The CCD camera 35 is moved so as to change the target viewing window 4.

  Next, the actual single crystal growth process will be described. First, a predetermined raw material is put into each crucible 11, and each crucible 11 is installed at a predetermined position in the corresponding heating coil portion. Subsequently, pressure control is performed by exhausting the space inside the chamber 4 and introducing a specific gas as necessary. After this pressure control is completed or in parallel with the pressure control, high-frequency power is applied to the heating coil 17, and the crucible 11 is heated to start melting the raw materials. When the raw material melts and becomes a raw material melt, the raw material melt leaks from the through hole. At that time, the seed 5 is disposed immediately below the through hole by the seed drive mechanism 33. The leaked raw material melt comes into contact with the seed 5 to form a so-called seed touch state, and generates a meniscus that becomes a solid-liquid boundary at the contact portion. Each crystal growing unit 3 performs these operations almost simultaneously. Here, the state of meniscus generation in each crystal growth unit 3 is imaged by the CCD camera 35, and the appropriateness of the start of the pull-down operation is determined by the control device 39. For the crystal growth unit 3 that is determined to be appropriate to start the pulling operation, the seed drive mechanism 33 starts to pull down the seed 5 and the single crystal 9 is grown (see FIG. 3). In this embodiment, since the heating state and the like in each crystal growth unit 3 are basically the same, the pulling-down operation in the three crystal growth units 3 is expected to be performed simultaneously. Therefore, the seed drive mechanism 33 may have a single configuration, and all the seeds 5 may be simultaneously pulled down by the single seed drive mechanism 33. By this operation, it becomes possible to grow a plurality of single crystals having the same quality.

  In the above-described embodiment, the heating coil unit and the viewpoint of obtaining a clear image during meniscus imaging and the reduction of power loss in the region due to the increase of the region for connection of each heating coil unit and The accompanying structures such as the crucible 11 are shifted in height in the pull-down axis direction, and these are arranged so as to have a level difference. However, when the length of the crucible 11 is increased in order to obtain a long single crystal, or when the number of crystal growth units is increased, the lower end portion of the first heating coil portion to the upper end portion of the last heating coil portion. As a result, the chamber 4 becomes large, which may cause problems in exhaust efficiency, installation area, and the like. In this case, all the heating coil sections and thus the crystal growth unit may be installed at the same height on the pulling shaft without providing the above-described steps. In this case, by reducing the depth of focus of the CCD camera 35, it is possible to compensate for a decrease in the resolution due to other overlapping meniscus images. In addition, in the case of the arrangement, since there is no difference in arrangement between the first unit and the other unit that only the last unit had when the step was added, the crystal growth caused by the arrangement is eliminated. There is also an advantage that the characteristics of the unit can be made uniform. In the above-described embodiment, each heating coil section has the same number of turns, winding diameter, winding interval, coil length, and the like. However, for example, as described above, when the characteristics of the first unit and the last unit are not the same due to differences in arrangement with other units, etc., the number of turns of the coil for the heating coil in a specific unit, It is good also as matching the loss part of each coil part by making at least any one of a winding diameter, a winding space | interval, and coil length different from another coil. This makes it easy to equalize the loss caused by the arrangement. Furthermore, in the present embodiment, the case where the number of the crucibles 11 and the corresponding configurations is three is illustrated, but in the present invention, these configurations may be two or further increased.

  In the present embodiment, the apparatus is configured such that a single CCD camera 35, a single high-frequency introduction end 21, a single high-frequency power source, and a single heating coil 17 are disposed in the chamber 4. It is intended to simplify the configuration and reduce the cost required for device construction. In particular, when the number of crystal growth units to be used is increased, it may be difficult to dispose the CCD camera together. However, when the number of crystal growth units is several as in this embodiment, individual CCD cameras may be arranged so as to correspond to the individual crystal growth units. As a result, there is no time lag when acquiring the meniscus image between the crystal growing units. For example, when the seed 5 is pulled down by the single seed drive mechanism 33, the pulling down is preferably started for a plurality of crystals. The timing can be obtained.

  As described above, according to the present invention, in a manufacturing process for simultaneously growing a plurality of single crystals, a plurality of crystal growth units arranged in the same chamber are used to generate a high frequency signal at a time using a single high frequency power source. By applying electric power, it becomes possible to grow single crystals that are more suitable and stable than the plurality of single crystal growth units. Accordingly, a plurality of single crystals can be simultaneously produced with good reproducibility.

1: Pulling device, 3: Crystal growth unit, 4: Chamber, 5: Seed, 9: Single crystal, 11: Crucible, 13: After heater, 17: Heating coil, 19: Crucible stage, 21: High-frequency introduction end, 25 : Outer tube, 31: seed holder, 33: seed drive mechanism, 35: CCD camera, 39: control device, 41: camera support rail, 41a: support table, 41b: camera swing mechanism, 41c: swing shaft

Claims (6)

Leakage of raw material melt held in the crucible having a cylindrical shape that becomes a closed portion with a closed bottom portion, and having a through hole that penetrates the closed portion from the inside of the cylindrical shape to the outside from the through hole The seed that determines the crystal orientation when the raw material melt is crystallized is brought into contact with the leaked raw material melt, and the seed is pulled down along a predetermined pulling axis to grow the seed as a base point. A single crystal pulling device for obtaining a crystal,
A plurality of the crucibles arranged equally around a predetermined central axis;
A plurality of heating coil portions arranged by winding each of the crucibles coaxially with the crucible,
The plurality of heating coil units are connected in series, and electric power is supplied to the plurality of heating coil units from a single introduction end.   The coil axes that are the central axes of the plurality of heating coil portions are parallel to each other, and the flow directions of the currents flowing through the heating coil portions are the same when the coil axis is used as a reference. 2. The apparatus for pulling down a single crystal according to claim 1, wherein a winding direction of the coil in the portion is determined.   The plurality of heating coil portions are each configured to be wound so that directions of magnetic fields formed by the respective heating coil portions are parallel and in the same direction. A device for pulling down a single crystal according to claim 1.   Even when the plurality of heating coil portions move a coil axis that is a central axis of the heating coil portion around the predetermined central axis, the coil axes do not overlap each other. The single crystal pulling device according to any one of claims 1 to 3, wherein the single crystal pulling device is arranged so as to be shifted from each other in a predetermined central axis direction.   The plurality of heating coil portions include a heating coil portion made of a coil in which at least one of the number of turns of the coil, the winding diameter, the winding interval, and the coil length is different from that of the other coil portions. The single crystal pulling device according to any one of claims 1 to 4, characterized in that: The heating coil unit and the crucible inside, further comprising a chamber constituting a sealed space, and an imaging means capable of observing the lower part of the crucible,
6. The chamber according to claim 1, wherein the chamber has a plurality of observation windows on a wall surface of the chamber closest to each of the crucibles so that the imaging unit can observe the lower part from the outside of the chamber. Single crystal pulling device.

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