JP3585731B2 - Magnetic field application type single crystal manufacturing equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for producing, for example, a silicon single crystal used as a semiconductor material, and more particularly to a magnetic field applying type single crystal producing apparatus provided with a magnetic field generator for applying a magnetic field to a crystal raw material melt.
[0002]
[Prior art]
FIG. 9 is a configuration diagram of a conventional single crystal manufacturing apparatus described in, for example, a CZ method (Czochralski method) described in Japanese Patent Publication No. 3-63030.
As shown in the figure, a crucible 2 filled with a single crystal raw material melt 1 (hereinafter, referred to as melt 1) is heated by a heater 3, and the single crystal material is always kept in a molten state. When the seed crystal 4 is inserted into the melt 1 and the seed crystal 4 is pulled up at a certain speed by the pulling drive mechanism 5, the crystal grows in the solid-liquid interface boundary layer 6 and the single crystal 7 Is generated.
At this time, the liquid motion of the melt 1 induced by the heating of the heater 3, that is, the heat convection 8 is generated.
[0003]
The cause of the generation of the heat convection 8 is explained as follows. That is, the thermal convection 8 generally occurs when the balance between the buoyancy due to the thermal expansion of the fluid and the viscous force of the fluid is broken. The dimensionless quantity representing the balance between the buoyancy and the viscous force is the Grashof number N_GrIt is.
[0004]
N_Gr＝ g ・ α ・ △ T ・ R³/ Ν²
Where g: gravity acceleration
α: coefficient of thermal expansion of the melt
ΔT: Crucible radial temperature difference
R; crucible radius
ν: kinematic viscosity coefficient of the melt
[0005]
In general, the Grashof number N_GrExceeds a critical value determined by the geometric dimensions of the melt 1, thermal boundary conditions, and the like, a thermal convection 8 occurs in the melt 1. Usually N_Gr> 10⁶, The convection 8 of the melt 1 becomes turbulent,_Gr> 10⁹Then it is in a disturbed state. Under the current melt conditions for pulling a single crystal having a diameter of 7.62 to 10.16 cm (3 to 4 inches), N_Gr> 10⁹The melt 1 is in a disturbed state, and the surface of the melt, that is, the solid-liquid interface boundary layer 6 is in a wavy state.
[0006]
When the heat convection 8 in such a disturbed state exists, temperature fluctuation in the melt 1, particularly in the solid-liquid interface boundary layer 6 becomes severe, and the thickness and the position and time of the solid-liquid interface boundary layer 6 become large. The fluctuation is severe, and the microscopic remelting of the growing crystal becomes remarkable, and dislocation loops, stacking faults, and the like occur in the grown single crystal 7. In addition, this defective portion is generated non-uniformly in the single crystal pulling direction due to irregular fluctuations of the solid-liquid interface boundary layer 6.
Further, impurities 9 dissolved in the melt 1 are conveyed to the heat convection 8 from the inner surface of the crucible 2 with which the high-temperature melt 1 (for example, about 1500 ° C.) is in contact, and dispersed throughout the melt 1. The impurities 9 serve as nuclei, causing dislocation loops, defects, growth stripes, and the like in the single crystal 7 to degrade the quality of the single crystal 7. For this reason, when an LSI wafer is manufactured from such a single crystal 7, the wafer including the defective portion cannot be used because the electrical characteristics are deteriorated, and the yield is deteriorated.
[0007]
In the future, the diameter of the single crystal 7 will gradually increase, but as can be seen from the above equation of Grashof number, as the diameter of the crucible 2 increases, the number of Grashof increases, and the heat convection 8 of the melt 1 increases. The intensity is further increased, and the quality of the single crystal 7 continues to deteriorate. Therefore, a method of applying a DC magnetic field to the melt 1 has been proposed in order to suppress the thermal convection 8 and perform single crystal pulling under growth conditions close to a thermally and chemically equilibrium state.
FIG. 10 is a configuration diagram of a conventional magnetic field application type single crystal manufacturing apparatus. As shown in the drawing, the magnet 10 is arranged on the outer periphery of the crucible 2 so that a uniform magnetic field is applied to the melt 1 in the direction of arrow 11 which is a direction orthogonal to the single crystal pulling direction. The melt 1 of the single crystal 7 is generally a conductor having electric conductivity σ. When a fluid having electrical conductivity moves by thermal convection 8, the fluid moving in a direction not parallel to the magnetic field application direction 11 receives a magnetoresistive force according to Lenz's law. Therefore, the motion of the heat convection 8 is stopped. In general, the magnetoresistance when a magnetic field is applied, that is, the magnetic viscosity coefficient ν_cfiIs
[0008]
ν_cfi= (ΜHD)²σ / ρ
Here, μ; permeability of the melt
H: magnetic field strength
D: Crucible diameter
σ: electric conductivity of the melt
ρ; density of melt
[0009]
When the magnetic field strength increases, the magnetic viscosity coefficient ν_cfiAnd the Grashof number N shown above_GrBecomes larger, and the Grashof number decreases rapidly, and the Grashof number can be made smaller than the critical value by a certain magnetic field strength. Thereby, the heat convection of the melt 1 is completely suppressed. By applying the magnetic field in this way, the thermal convection 8 is suppressed, so that the above-mentioned impurity contained in the single crystal 7, the occurrence of dislocation loops, the occurrence of defects, and the occurrence of growth stripes are eliminated, and the uniformity in the single crystal pulling direction is uniform. A single crystal 7 of high quality is obtained, and the quality and yield of the single crystal 7 are improved.
[0010]
In recent years, a method of applying a cusp magnetic field has been proposed as a magnetic field application type single crystal manufacturing apparatus having the above characteristics. The cusp magnetic field is a magnetic field that is optimal for generating a high-quality single crystal by generating a horizontal magnetic field that is symmetrical with respect to the melt in the crucible.
FIG. 11 is a configuration diagram of a conventional magnetic field application type single crystal manufacturing apparatus using a cusp magnetic field described in, for example, JP-A-61-222984. In addition, 1-4, 6 and 7 in a figure are the same as that shown in FIG. 9 and FIG.
As shown in the figure, an upper coil 12 is disposed above the crucible 2 and a lower coil 13 is disposed below the crucible 2 so that the same poles are opposed to each other. The upper coil 12 is attached to a guide body 14 installed in parallel with the two axes of the crucible so as to be movable in the vertical direction, and the lower coil 13 is fixed to a fixed end. With such a magnet arrangement, a cusp magnetic field indicated by the magnetic field application direction 15 is generated in the melt 1 in the crucible 2.
[0011]
When such a cusp magnetic field is used, as the single crystal 7 is pulled up, the surface of the melt 1 decreases and the amount of the melt 1 decreases, and the optimum magnetic field distribution changes accordingly. For this reason, by moving the upper coil 12 in the vertical direction, the cusp magnetic field applied to the raw material melt 1 in the crucible 2 is always kept optimal, and a high-quality single crystal is manufactured.
[0012]
Further, as another example of a conventional magnetic field application type single crystal manufacturing apparatus by applying a cusp magnetic field, both the upper coil 12 and the lower coil 13 are fixed and the exciting current of at least one of the coils 12 and 13 is made variable. There is also shown one in which the magnetomotive forces of 12, 13 are adjusted so that the cusp magnetic field applied to the raw material melt 1 in the crucible 2 is always kept optimal.
[0013]
[Problems to be solved by the invention]
Since the conventional magnetic field applying type single crystal manufacturing apparatus by applying a cusp magnetic field is configured as described above, the coil 12 is moved or the coil 12 is moved in accordance with the state of the melt 1 which fluctuates as the single crystal is pulled up. , 13 are variable, and an optimum cusp magnetic field is always applied.
However, moving the coil 12 requires a mechanical position adjusting mechanism, which makes the device itself complicated and expensive, and the cusp magnetic field used for pulling a single crystal as described above is relatively strong. A magnetic force was required, and the movement of the coil 12 required precise position fluctuation against such a strong magnetic force, and it was not easy to keep the cusp magnetic field at an optimum.
Further, in order to adjust the magnetomotive force of the coils 12 and 13 by making the exciting currents of the coils 12 and 13 variable, a large power supply for the coils 12 and 13 is required, and the power supply cost is high and the apparatus is expensive. Was to become.
[0014]
The present invention has been made in order to solve the above problems, and can easily adjust a cusp magnetic field applied to a raw material melt in a crucible at the time of pulling a single crystal so as to always be optimal. It is an object of the present invention to provide an inexpensive and simple magnetic field applying type single crystal manufacturing apparatus capable of manufacturing a high quality single crystal.
[0015]
[Means for Solving the Problems]
A magnetic field application type single crystal manufacturing apparatus according to claim 1 of the present invention includes a single crystal pulling unit that generates a single crystal by inserting a seed crystal into a raw material melt in a crucible and pulling the seed crystal. A magnetic field generating unit for applying a radial cusp magnetic field to the raw material melt in the crucible, which is equiaxially symmetric with respect to the crucible axis, wherein the magnetic field generating units are disposed oppositely above and below the crucible. , A pair of main coils connected in series, and one sub-coil arranged coaxially with the main coil, the direction and magnitude of the exciting current thereof being variable and having a smaller magnetomotive force than the main coil. It is a thing.
[0016]
According to a second aspect of the present invention, there is provided a magnetic field applying type single crystal manufacturing apparatus as set forth in the first aspect, wherein a distance between the main coils is set to about half of a diameter of the main coil, and a magnetomotive force of the sub coil is generated by the main coil. It does not exceed 0.3 times the magnetic force.
[0017]
According to a third aspect of the present invention, there is provided a magnetic field applying type single crystal manufacturing apparatus according to the first or second aspect, wherein the pair of main coils and the sub-coil are formed of a superconducting coil, and the sub-coil is a center between the pair of main coils. It is arranged in.
[0018]
According to a fourth aspect of the present invention, there is provided a magnetic field application type single crystal manufacturing apparatus according to any one of the first to third aspects, wherein the pair of main coils and the sub-coil comprise a superconducting coil maintained at a very low temperature. The current lead of the coil and the current lead of the main coil are partially shared to reduce heat generation.
[0019]
According to a fifth aspect of the present invention, there is provided a magnetic field applying type single crystal manufacturing apparatus according to any one of the first to fourth aspects, wherein the sub-coil is disposed at the center between the pair of main coils, and The outer periphery is covered with a magnetic shield.
[0020]
According to a sixth aspect of the present invention, there is provided a magnetic field applying type single crystal manufacturing apparatus according to the fifth aspect, wherein a pair of the main coil and the sub-coil are formed of a superconducting coil, and a magnetic shield is a part of a vacuum vessel accommodating the superconducting coil. It is what it was.
[0021]
According to a seventh aspect of the present invention, there is provided a magnetic field applying type single crystal manufacturing apparatus according to the fifth or sixth aspect, wherein the magnetic shield is balanced with the first cutout for connection to the outside and the electromagnetic force. A second notch, wherein the first and second notches are arranged with vertical symmetry and rotational symmetry about the axis a plurality of times.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram of a magnetic field application type single crystal manufacturing apparatus according to Embodiment 1 of the present invention. In the figure, 16 is a crucible, 17 is a single crystal raw material melt filled in the crucible 16 (hereinafter referred to as melt 17), 18 is a heater for heating the crucible 16, and 19 is inserted into the melt 17. A seed crystal, 20 is a solid-liquid interface boundary layer on the surface of the melt 17, and 21 is a generated single crystal. A single crystal pulling section is constituted by these 16-21 and a single crystal pulling drive mechanism (not shown). 22a and 22b are a pair of main coils arranged above and below the crucible 16 so that the same poles are opposed to each other, and 23 is arranged between the main coils 22a and 22b and adjacent to one main coil 22a. The sub-coils are provided, and these coils 22a, 22b, and 23 constitute a magnetic field generating unit.
Reference numeral 24 denotes a direction in which the cusp magnetic field applied to the melt 17 in the crucible 16 by the main coils 22a and 22b and the sub coil 23, and 25 denotes a point where the magnetic field is zero. Numeral 26 denotes thermal convection, which is a liquid motion of the melt 17 induced by heating of the heater.
[0023]
FIG. 2 is a diagram showing connection between the main coils 22a and 22b and the sub coil 23 and the power supply. As shown in the figure, the pair of main coils 22a and 22b are connected in series and connected to one main coil power supply 27. On the other hand, the sub-coil 23 is connected to a sub-coil power supply 28 via a polarity switch 29, and is configured to have both polarities and a variable amount of current. The main coils 22a and 22b generate a magnetomotive force of, for example, about 100 kA, and the sub coil 23 generates a magnetomotive force of about ± 10 kA.
The pair of main coils 22a and 22b are energized in the opposite direction, are excited so that the same poles are opposed to each other, and in the separately excited sub coil 23, by adjusting the direction and magnitude of the exciting current, The vertical position of the point 25 of the magnetic field 0 of the cusp magnetic field is adjusted.
[0024]
Next, the operation will be described.
The crucible 16 is heated by the heater 18, and the single crystal raw material filled in the crucible 16 is always kept in the state of the melt 17. When the seed crystal 19 is inserted into the melt 17 and the seed crystal 19 is pulled up by a pulling drive mechanism at a certain speed, the crystal grows in the solid-liquid interface boundary layer 20 and a single crystal 21 is formed. Is done. Further, as shown by the magnetic field application direction 24, the main coils 22 a and 22 b and the sub-coil 23 generate a radial cusp magnetic field which is equiaxially symmetric with respect to the crucible 16 axis in the melt 17 in the crucible 16. . In FIG. 1, the point 25 of the magnetic field 0 is set on the solid-liquid interface boundary layer 20 which is the surface of the melt 17.
When the single crystal 21 is pulled up, as the single crystal 21 is pulled up, the surface of the melt 17 and the amount of the melt 17 decrease, and the optimum magnetic field distribution changes accordingly. Therefore, by adjusting the exciting current of the sub-coil 23, the point 25 of the magnetic field 0 is lowered as the single crystal 21 is pulled up, and the cusp magnetic field applied to the melt 17 in the crucible 16 is always kept optimal. In this case, by adjusting the exciting current of the sub-coil 23, the position 25 of the magnetic field 0 can be moved up and down within a range of ± about 25 mm.
[0025]
In this way, by always applying the optimal cusp magnetic field to the melt 17 in the crucible 16, the thermal convection 26 is effectively suppressed, and the inclusion of impurities in the single crystal 21, the generation of dislocation loops, the occurrence of defects, and Generation is eliminated, and a high-quality single crystal 7 uniform in the single crystal pulling direction is obtained.
[0026]
In this embodiment, a cusp magnetic field is generated by a pair of main coils 22a and 22b connected in series and a sub coil 23 having a smaller magnetomotive force, and the direction and magnitude of the exciting current of the sub coil 23 are reduced. Adjustment was made so that the cusp magnetic field was always kept optimal when the single crystal 21 was pulled up. For this reason, a mechanical position adjusting mechanism is not necessary unlike the conventional method of moving the coil 12 against magnetic force, and the apparatus can be inexpensive and simple, and the optimal cusp magnetic field can be easily adjusted electrically. And a high quality single crystal can be produced.
Also, since the pair of main coils 22a and 22b are connected in series, only one large power supply for the main coils 22a and 22b is required, and the separately provided power supply for the sub-coil 23 is the main coil 22a. , 22b, the power supply cost can be reduced, and the apparatus cost can be further reduced.
[0027]
In the above embodiment, the sub coil 23 is arranged between the main coils 22a and 22b and adjacent to one main coil 22a. However, the position of the sub coil 23 is not limited to this, and the main coil 22a, A similar effect can be obtained at any position between the coils 22b and at a close position outside the main coils 22a and 22b.
[0028]
Embodiment 2 FIG.
In the first embodiment, the distance between the pair of main coils 22a and 22b is usually about half the diameter of the main coils 22a and 22b. In this case, the magnetomotive force of the sub coil 23 is smaller than that of the main coils 22a and 22b. What does not exceed 0.3 times of the one is sufficient.
For example, when the pair of main coils 22a and 22b have a diameter of about 2.2 m and an interval of about 1.1 m, the relationship between the magnetomotive force of the sub-coil 23 and the positional change of the point 25 of the magnetic field 0 is shown in FIG. As shown in the figure, when the magnetomotive force of the sub coil 23 is ± 30% of that of the main coils 22a and 22b, the point 25 of the magnetic field 0 can be displaced within a range of ± 0.2 m.
As described above, if the distance between the pair of main coils 22a and 22b is about half the diameter of the main coils 22a and 22b and the magnetomotive force of the sub coil 23 is 0.3 times that of the main coils 22a and 22b, the magnetic field The position of the zero point 25 can be adjusted within a range of about ± 10% of the diameter of the main coils 22a and 22b, and this adjustment range is sufficient for the crucible 16. For this reason, by making the magnetomotive force of the sub coil 23 not more than 0.3 times that of the main coils 22a and 22b, the power supply cost can be effectively reduced, and the cusp by adjusting the position of the point 25 of the magnetic field 0 can be effectively reduced. The magnetic field can be optimized.
[0029]
Embodiment 3 FIG.
FIG. 4 is a configuration diagram of a magnetic field application type single crystal manufacturing apparatus according to Embodiment 3 of the present invention. As shown in the figure, the main coils 30a and 30b and the sub coil 31 are constituted by superconducting coils, and the superconducting sub coil 31 is disposed at the center between the pair of superconducting main coils 30a and 30b. The connections between the superconducting main coils 30a and 30b and the superconducting subcoil 31 and the power supply are the same as those in FIG. 2 shown in the first embodiment.
Generally, in a superconducting coil, a phenomenon called quench may occur in which the excited state of the coil disappears in a short time. In this embodiment, the superconducting main coils 30a and 30b are connected in series and arranged so that the same poles oppose each other. Therefore, when a quench occurs in one of the superconducting main coils 30a, 30b, the excitation state disappears in both superconducting main coils 30a, 30b, but the superconducting sub-coil disposed in the center between the superconducting main coils 30a, 30b Since opposing induced electromotive forces from the two superconducting main coils 30a and 30b work and cancel each other, no induced electromotive force is generated in the superconducting auxiliary coil 31. Conversely, even if quench occurs in the superconducting sub-coil 31, no induced electromotive force occurs in the superconducting main coils 30a, 30b.
Normally, a protection circuit such as a resistor or a diode is inserted to protect the coil from the induced electromotive force generated at the time of quenching. However, in this embodiment, generation of the induced electromotive force at the time of quench can be prevented. In addition, the protection circuit can be simplified.
[0030]
Embodiment 4 FIG.
FIG. 5 is a connection diagram of a magnetic field application type single crystal manufacturing apparatus according to Embodiment 4 of the present invention. The superconducting coils 30a, 30b, and 31 are housed in a cold container or the like that is kept in a cryogenic state with liquid helium or the like in a vacuum container, and are provided with a current lead 32 laid at room temperature to be placed in a room temperature room. 28 and 29. As shown in the figure, the current lead 32 of the superconducting sub-coil 31 and the current lead 32 of the superconducting main coils 30a and 30b are partially shared to reduce the amount of heat generated, so that the current lead 32 to the cryogenic temperature region is reduced. The heat penetration can be reduced, and the superconducting coils 30a, 30b, 31 can be reliably maintained in the superconducting state.
[0031]
Embodiment 5 FIG.
FIG. 6 is a configuration diagram of a magnetic field application type single crystal manufacturing apparatus according to Embodiment 5 of the present invention. As shown in the figure, the superconducting sub-coil 31 is disposed at the center between the pair of superconducting main coils 30a and 30b. The superconducting coils 30a, 30b, 31 are housed in a vacuum container 33, and a magnetic shield 34 made of a ferromagnetic material such as iron is provided on the outer periphery of the container 33. Thereby, the leakage magnetic field can be reduced.
Also, even if the quench occurs in the superconducting main coils 30a, 30b, since the pair of superconducting main coils 30a, 30b are connected in series, the fluctuation of the exciting current is the same, and the magnetic shield 34 and the superconducting main coil 30a , 30b are balanced. Further, since the superconducting sub-coil 31 is installed at the center of the magnetic shield 34 in the vertical direction, even when the exciting current of the superconducting sub-coil 31 changes or quench occurs, the unbalanced electromagnetic force does not work, and the The balanced state of the electromagnetic force between the superconducting sub-coil 31 is maintained. Therefore, the superconducting coils 30a, 30b, 31 are easily supported, and the electromagnetic force supporting structure is simplified.
[0032]
In the above embodiment, the superconducting coils 30a, 30b and 31 are used. However, the normal conducting coil is used, and the normal conducting sub-coil is arranged at the center between the pair of normal conducting main coils. A magnetic shield 34 may be provided on the outer periphery of the device, so that a balanced state of the electromagnetic force can be maintained and the leakage magnetic field can be reduced.
[0033]
Embodiment 6 FIG.
FIG. 7 is a configuration diagram of a magnetic field application type single crystal manufacturing apparatus according to Embodiment 6 of the present invention. In the fifth embodiment, the superconducting coils 30a, 30b, and 31 are used, and the magnetic shield 34 is partially used for the outer peripheral portion of the vacuum vessel 33 as shown in FIG.
As a result, the magnetic shield 34 and the vacuum vessel 33 can be partially used in common, and the apparatus can be reduced in size and cost can be reduced.
[0034]
Embodiment 7 FIG.
FIG. 8 is a configuration diagram of a magnetic field application type single crystal manufacturing apparatus according to Embodiment 7 of the present invention. The magnetic shield 34 may be provided with a notch for evacuation of an evacuation port, extraction of a measurement line, extraction of a current lead, and the like. As shown in the figure, in order to draw out the measurement line 35 and to provide the vacuum valve 36 in the magnetic shield 34 in the fifth or sixth embodiment, the measurement line notch 37a and the first notch are used as the first notch. A notch 37b for a vacuum valve is provided, and a second notch is formed between the notches 37a and 37b at a position having vertical symmetry and a position having, for example, four-fold rotational symmetry about an axis. As the notches, symmetrically arranged notches 38a and 38b are provided. In addition, the notch portions 37 and 38 are provided with lids 39 for vacuum sealing, respectively.
Thereby, the unbalanced electromagnetic force can be reduced, and the balanced state of the electromagnetic force generated between the superconducting coils 30a, 30b, 31 and the magnetic shield 34 is maintained, and the superconducting coils 30a, 30b, 31 are easily supported. Therefore, the electromagnetic force supporting structure is simplified.
[0035]
Note that the symmetrically arranged notches 38a and 38b are provided at a position having vertical symmetry and a position having, for example, four times rotational symmetry around the axis. However, the rotational symmetry is not limited to four times. Instead, any material may be used as long as it is arranged at equal intervals in the circumferential direction of the magnetic shield 34.
[0036]
【The invention's effect】
As described above, the magnetic field application type single crystal manufacturing apparatus according to claim 1 according to the present invention provides a single crystal that forms a single crystal by inserting a seed crystal into a raw material melt in a crucible and pulling up the seed crystal. A lifting part, and a magnetic field generating part for applying a radial cusp magnetic field to the raw material melt in the crucible in a radially equiaxed manner with respect to the crucible axis, wherein the magnetic field generating part is vertically positioned around the crucible. A pair of main coils arranged in the same direction and connected in series, and one sub coil arranged coaxially with the main coil, the direction and magnitude of the exciting current being variable and having a magnetomotive force smaller than the main coil. Because it is composed of coils, the optimal cusp magnetic field can be easily adjusted and maintained electrically easily, high-quality single crystals can be manufactured, and power supply costs can be reduced, and an inexpensive and simple device configuration is provided. it can.
[0037]
According to a second aspect of the present invention, there is provided a magnetic field applying type single crystal manufacturing apparatus according to the first aspect, wherein a distance between the main coils is set to about half of a diameter of the main coil, and a magnetomotive force of the sub coil is set to a value of the main coil. Since it does not exceed 0.3 times the magnetomotive force, a high-quality single crystal can be manufactured and the power supply cost can be effectively reduced.
[0038]
According to a third aspect of the present invention, there is provided a magnetic field applying type single crystal manufacturing apparatus according to the first or second aspect, wherein the pair of main coils and the sub coil are formed of a superconducting coil, and the sub coil is disposed between the pair of main coils. Since it is arranged at the center, the generation of induced electromotive force at the time of quenching can be prevented, so that the protection circuit can be simplified.
[0039]
According to a fourth aspect of the present invention, there is provided a magnetic-field-applied single-crystal manufacturing apparatus according to any one of the first to third aspects, wherein the pair of main coils and the sub-coils are each formed of a superconducting coil maintained at an extremely low temperature. Since the current lead of the sub coil and the current lead of the main coil are partially shared to reduce the amount of heat generated, heat penetration from the current lead to the cryogenic region can be reduced, and the superconducting coil can be reliably maintained in the superconducting state. it can.
[0040]
According to a fifth aspect of the present invention, there is provided a magnetic field applying type single crystal manufacturing apparatus according to any one of the first to fourth aspects, wherein the sub coil is disposed at the center between the pair of main coils, and the main coil and the sub coil are arranged. Since the outer circumference of the coil is covered with a magnetic shield, the electromagnetic force between the magnetic shield and the coil can be kept in a balanced state, the structure for supporting the electromagnetic force of the coil can be simplified, the cost can be reduced, and the leakage magnetic field can be reduced. Can be.
[0041]
According to a sixth aspect of the present invention, there is provided a magnetic field applying type single crystal manufacturing apparatus according to the fifth aspect, wherein a pair of the main coil and the sub coil are formed of a superconducting coil, and a magnetic shield is provided in the vacuum container for accommodating the superconducting coil. As a result, the size of the device can be reduced, the cost can be reduced, and the leakage magnetic field can be reduced.
[0042]
According to a seventh aspect of the present invention, there is provided a magnetic field applying type single crystal manufacturing apparatus according to the fifth or sixth aspect, wherein the magnetic shield is provided with a first cutout for connection to the outside, and an electromagnetic force balance. And a second notch for maintaining the coil and the magnetic shield, since the first and second notches are arranged with vertical symmetry and rotational symmetry about the axis a plurality of times. Thus, an equilibrium state of the electromagnetic force generated between the coils can be maintained, and an inexpensive device configuration with a simple electromagnetic force supporting structure for the coil can be provided.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a magnetic field application type single crystal manufacturing apparatus according to a first embodiment of the present invention.
FIG. 2 is a connection diagram of the magnetic field application type single crystal manufacturing apparatus according to the first embodiment of the present invention.
FIG. 3 is a diagram for explaining a descent of a magnetic field application type single crystal manufacturing apparatus according to a second embodiment of the present invention.
FIG. 4 is a configuration diagram of a magnetic field application type single crystal manufacturing apparatus according to a third embodiment of the present invention.
FIG. 5 is a connection diagram of a magnetic field application type single crystal manufacturing apparatus according to a fourth embodiment of the present invention.
FIG. 6 is a configuration diagram of a magnetic field application type single crystal manufacturing apparatus according to a fifth embodiment of the present invention.
FIG. 7 is a configuration diagram of a magnetic field application type single crystal manufacturing apparatus according to a sixth embodiment of the present invention.
FIG. 8 is a configuration diagram of a magnetic field application type single crystal manufacturing apparatus according to a seventh embodiment of the present invention.
FIG. 9 is a configuration diagram of a conventional single crystal manufacturing apparatus.
FIG. 10 is a configuration diagram of a conventional magnetic field application type single crystal manufacturing apparatus.
FIG. 11 is a configuration diagram of a magnetic field application type single crystal manufacturing apparatus according to another conventional example.
[Explanation of symbols]
16 crucible, 17 raw material melt, 19 seed crystal, 21 single crystal,
22a, 22b main coil, 23 sub coil, 24 cusp magnetic field application direction,
29 polarity switcher, 30a, 30b superconducting main coil,
31 superconducting auxiliary coil, 32 current lead, 33 vacuum vessel,
34 magnetic shield, 37a notch for measurement line as first notch, 37b notch for vacuum valve as first notch,
38a, 38b Symmetrically arranged notches as second notches.

Claims (7)

A seed crystal is inserted into the raw material melt in the crucible, and a single crystal pulling unit that generates a single crystal by pulling up the seed crystal, and the raw material melt in the crucible is equiaxially symmetric with respect to the crucible axis. And a magnetic field generating unit for applying a radial cusp magnetic field, wherein the magnetic field generating unit is disposed above and below the crucible so as to face each other and connected in series, and a pair of main coils connected in series, and coaxial with the main coil. A magnetic field applying type single crystal manufacturing apparatus, comprising: a single sub-coil arranged so as to be variable in direction and magnitude of an exciting current and having a smaller magnetomotive force than the main coil. 2. The magnetic field according to claim 1, wherein the distance between the main coils is about half the diameter of the main coil, and the magnetomotive force of the sub coil does not exceed 0.3 times the magnetomotive force of the main coil. Applied single crystal manufacturing equipment. 3. A magnetic field applying type single crystal manufacturing apparatus according to claim 1, wherein the pair of main coils and the sub coil are formed of a superconducting coil, and the sub coil is disposed at the center between the pair of main coils. A pair of main coil and sub-coil are composed of a superconducting coil that is kept in a cryogenic state, and the current lead of the sub-coil and the current lead of the main coil are partially shared to reduce heat generation. The magnetic field application type single crystal manufacturing apparatus according to claim 1. The magnetic field applying type single crystal according to any one of claims 1 to 4, wherein the sub-coil is disposed at the center between the pair of main coils, and the outer circumference of the main coil and the sub-coil is covered with a magnetic shield. manufacturing device. The magnetic field application type single crystal manufacturing apparatus according to claim 5, wherein the pair of main coils and sub-coils are composed of superconducting coils, and the magnetic shield is a part of a vacuum container that houses the superconducting coils. The magnetic shield is provided with a first notch for connection to the outside and a second notch for maintaining the balance of electromagnetic force, and the first and second notches are vertically symmetric. 7. The magnetic field applying type single crystal manufacturing apparatus according to claim 5, wherein the magnetic field applying type single crystal manufacturing apparatus is arranged with a plurality of rotational symmetries around the axis.

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