JP3535343B2 - Magnetic field application type single crystal manufacturing equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal manufacturing apparatus for pulling and manufacturing, for example, a silicon crystal used as a semiconductor device material from a crystal raw material melt, and particularly to a magnetic field for applying a magnetic field to the crystal raw material melt in the crystal pulling portion. The present invention relates to a magnetic field application type single crystal manufacturing apparatus having a generator.

[0002]

2. Description of the Related Art FIG. 10 is a block diagram showing a conventional single crystal pulling apparatus by the CZ method (Czochralski method) described in Japanese Patent Publication No. 3-61630. In this conventional single crystal pulling apparatus, the single crystal raw material melt 1 (hereinafter,
The melt is filled in the crucible 2. A heater 3 is arranged outside the crucible 2, and the single crystal raw material contained in the crucible 2 is melted by the heating of the heater 3 and is always kept in a molten state. Then, after the seed crystal 4 is immersed in the melt 1, the pull-up drive mechanism 5
When the seed crystal 4 is pulled up at a constant rate by the above, the crystal grows in the solid-liquid interface boundary layer 6, and the single crystal 7
Is generated. At this time, the fluid movement of the melt 1, that is, the thermal convection 8 is induced by the heating of the heater 3.

The cause of generation of the thermal convection 8 will be explained as follows. That is, the thermal convection 8 generally occurs when the balance between the buoyant force due to the thermal expansion of the fluid and the viscous force of the fluid is broken.
A non-dimensional amount representing the balance between the buoyancy and the viscous force is the Grashof number N _Gr . NGr = g · α · ΔT · R ³ / ν ² where g: acceleration of gravity, α: coefficient of thermal expansion of melt, ΔT:
Crucible radial direction temperature difference, R: crucible radius, ν: melt kinematic viscosity coefficient.

Generally, when the Grashof number N _Gr exceeds a critical value determined by the geometrical dimensions of the melt 1, thermal boundary conditions, etc., thermal convection 8 is generated in the melt 1. Usually N
_{When Gr} > 10 ^6, the thermal convection 8 of the melt 1 becomes a turbulent state,
When N _Gr > 10 ⁹ , it is in a disturbed state. Under the melt conditions for pulling a single crystal having a diameter of 3 to 4 inches, which is currently performed, N _Gr > 10 ⁹ (according to the formula of N _Gr ) and the inside of the melt 1 is disturbed, and the surface of the melt 1 is That is, the solid-liquid interface boundary layer 6 becomes wavy.

The presence of such convective thermal convection 8 causes severe temperature fluctuations in the melt 1, especially in the solid-liquid interface boundary layer 6, and the thickness of the solid-liquid interface boundary layer 6 varies in position. In addition, the temporal fluctuation is severe, microscopic redissolution of the crystal during growth becomes remarkable, and dislocation loops, stacking faults, etc. occur in the grown single crystal 7. Moreover, this defective portion is nonuniformly generated in the single crystal pulling direction due to the irregular fluctuation of the solid-liquid interface boundary layer 6.

Further, a high temperature melt 1 (for example, 1500
Due to a chemical change between the melt 1 and the crucible 2 on the inner surface of the crucible 2 which is in contact with (° C.), The impurities 9 dissolved in the melt 1 from the inner surface of the crucible 2 are transferred to the thermal convection 8 and melt
Dispersed throughout the interior of. The impurities 9 serve as nuclei to generate dislocation loops, defects, growth fringes, etc. in the single crystal 7 and deteriorate the quality of the single crystal 7. Therefore, LSI (Large Scale Integratio
(n: large-scale integrated circuit), a wafer including a defective portion cannot be used because its electrical characteristics are deteriorated, resulting in poor yield.

In the future, the diameter of the single crystal 7 will become larger and larger, but as can be seen from the above equation of the Grashof number, the larger the diameter of the crucible 2, the larger the Grashof number,
The thermal convection 8 of the melt 1 becomes more violent, and the quality of the single crystal 7 will continue to deteriorate. Therefore, heat convection 8
A method of applying a DC magnetic field to the melt 1 has been proposed in order to suppress the above and pull the single crystal under the growth condition that is close to the equilibrium state thermally and chemically.

FIG. 11 is a block diagram showing a conventional single crystal pulling apparatus by applying a magnetic field. In the figure, the same parts as those of the single crystal pulling apparatus of FIG. In the conventional single crystal pulling apparatus shown in FIG. 11, the magnet 10 is arranged on the outer circumference of the crucible 2 and a uniform magnetic field in the direction indicated by an arrow 11 in the figure, that is, the direction perpendicular to the single crystal pulling direction is melted. It is adapted to be applied in the liquid 1. The melt 1 of the single crystal 7 is generally a conductor having an electric conductivity σ. Therefore, when the fluid having electric conductivity moves due to the thermal convection 8, the fluid moving in a direction not parallel to the magnetic field applying direction 11 receives a magnetic resistance force according to Lenz's law. Therefore, the movement of the thermal convection 8 is prevented. Generally, the magnetic resistance force when the magnetic field is changed, that is, the magnetic viscosity coefficient ν _{cf i} is expressed by the following equation. ν _cfi = (μHD) ² σ / ρ where μ: permeability of melt, H: magnetic field strength, D: diameter of crucible, σ: electrical conductivity of melt, ρ: density of melt.

Therefore, when the magnetic field strength is increased, the magnetic viscosity coefficient ν _cfi is increased, and ν in the above equation of the Grashof number N _Gr is increased, the Grashof number is rapidly decreased, and a certain magnetic field is generated. Depending on the strength, the Grashof number can be made smaller than the critical value. As a result, the thermal convection of the melt 1 8
Is completely suppressed. As described above, since the thermal convection 8 is suppressed by applying the magnetic field, the inclusion of impurities in the single crystal 7, the occurrence of dislocation loops, the occurrence of defects and growth stripes, etc. are eliminated, and the single crystal 7 is pulled in the pulling direction. A single crystal 7 of uniform quality is obtained, and the quality and yield of the single crystal 7 can be improved.

On the other hand, as a single crystal pulling apparatus for applying a magnetic field which exhibits such characteristics, there is one that employs a superconducting magnet which has been attracting attention in recent years.

12 and 13 are views showing a conventional single crystal pulling apparatus equipped with a superconducting magnet device. FIG. 12 is a configuration diagram viewed from the front direction, and FIG. 13 is a configuration diagram viewed from the top direction. Is. In each figure, the same parts as those of the single crystal pulling apparatus of FIG. In the conventional single crystal pulling apparatus shown in FIGS. 12 and 13, a cylindrical superconducting coil is used to apply a magnetic field in the direction of arrow 11 in FIG. Nos. 13 and 14 are installed outside the pulling apparatus chamber 12 at positions shown in the drawing in which the transverse magnetic field direction 11 and the coil central axis coincide with each other.

The superconducting coils 13 and 14 have an inner tank 16 filled with cryogenic (eg 4.2k) liquid helium 15.
It is housed inside and kept superconducting. Cooling container 17 for keeping the superconducting coils 13 and 14 in a cryogenic state
Each of a and 17b is composed of an inner tank 16 and an outer tank 18, and a radiation shield plate 19 which is installed between them and reduces the amount of heat entering from the outside. Small refrigerators 50a, 5
0b, 60a and 60b are cold storage containers 17a and 1a, respectively.
It is attached directly to 7b.

The compact refrigerators 50a and 50b are compressor units 5 for compressing refrigerating refrigerants (helium, for example) 51a and 51b circulating in the compact refrigerators 50a and 50b.
2a and 52b, and the frozen refrigerant 51 compressed by these
Expanders 53a and 5 for adiabatically expanding and cooling a and 51b
3b (53b is not shown) and the freezing stages 54a, 54 cooled to the radiation shield temperature (for example, 80K).
b (54b not shown) and helium recondenser 55 cooled to helium liquefaction temperature (eg 4.2K).
a and 55b (55b is not shown).

The small refrigerators 60a and 60b have a structure similar to that of the small refrigerators 50a and 50b.
61b, compressor units 62a and 62b, and expander 6
3a, 63b (63b is not shown), the freezing stages 64a, 64b (64b are not shown) having a radiation shield temperature, and the freezing stages 65a, 65b (65b are cooled to an extremely low temperature (for example, 20K)). And (not shown).

The superconducting coils 13 and 14 are connected in series by a power lead 20 laid at room temperature (for example, 300K), and an exciting current is supplied from a power source 21. The heat entering the outside from the power lead 20 is the small refrigerator 60.
a, 60b freezing stages 64a, 64b, 65a, 6
Removed by 5b. The helium gas in the inner tank 16 evaporated with the coil excitation is recondensed (liquefied) by the helium recondensers 55a and 55b of the small refrigerators 50a and 50b.
To be done. In this way, the cold containers 17a, 17b are always filled with liquid helium, and the superconducting coil 13,
14 can keep the superconducting state.

Also in the conventional single crystal pulling apparatus equipped with this superconducting magnet device, since the transverse magnetic field can be applied in the melt 1, the thermal convection 8 in the melt 1 is suppressed, and FIG.
Similar to the conventional single crystal pulling apparatus shown in FIG. 1, the single crystal 7 does not contain impurities, the generation of dislocation loops, the occurrence of defects and growth fringes, and the single crystal having a uniform quality in the pulling direction of the single crystal. 7 is obtained, and the quality and yield of the single crystal 7 can be improved.

Generally, the single crystal pulling apparatus has a crucible 2 and a pulling apparatus chamber 1 each time the pulling operation is completed.
It is necessary to clean the inner surface of 2. In a conventional single crystal pulling apparatus equipped with a superconducting magnet device, this cleaning is carried out in the following procedure. First, the support rod 22 installed to support the cold insulation containers 17a and 17b on which the electromagnetic force generated from the superconducting magnet device acts is removed. Then,
A cradle 29a holding the cold containers 17a and 17b,
The floor fixing rail 23 laid at the bottom of 29b is moved in the horizontal direction 24 to a fixed position (indicated by 25 in FIG. 13) to completely separate the main body of the single crystal pulling apparatus and the superconducting magnet apparatus. . In this state, crucible 2 and chamber 1
Perform 2 cleaning.

Further, for example, in the conventional single crystal pulling apparatus disclosed in Japanese Patent Publication No. 3-61630, as shown in FIGS. 14 and 15, the crucible 2 is connected by a U-shaped pipe. A magnetic field is applied to the melt 1 of the crucible 2 by a superconducting magnet arranged so as to surround it. The coils of this superconducting magnet are connected in series so that current is supplied from one power source. Further, this superconducting magnet can have a structure capable of moving in the horizontal direction (direction of arrow 24 in FIG. 15).

However, in the single crystal pulling apparatus for applying a transverse magnetic field in the melt 1 described above, convection occurs because a non-axisymmetric magnetic field (transverse magnetic field) is generated with respect to axisymmetric thermal convection. It has no effect on the flow in the radial direction that matches the magnetic field direction, and non-axial symmetry occurs in the thermal convection, and a single crystal with a uniform circular cross section cannot be obtained. There is a problem that the crystallinity is not uniform over the entire cross section. Therefore, in order to obtain a single crystal having a uniform circular cross section, and further, to obtain a single crystal having uniform crystallinity over the entire circular cross section, a radial cusp magnetic field is applied in the melt 1 in an equiaxial symmetry. The method of doing is proposed.

FIG. 16 shows, for example, Japanese Patent Laid-Open No. 58-217493.
FIG. 16A is a view showing a thermal convection and a magnetic field in a melt in a conventional single crystal pulling apparatus described in Japanese Patent Laid-Open Publication No. 16A, and FIG. 16A is a vertical sectional view and FIG. 16B is an upper sectional view. In this conventional single crystal pulling apparatus, superconducting magnets are provided above and below the crucible 2 so that an equiaxially symmetric and radial cusp magnetic field 11a is formed in the melt 1. Therefore,
A radial cusp magnetic field 11a is applied in the vicinity of the center of the melt 1 part of the crucible 2 to cause thermal convection 8 in the melt 1.
Are uniformly suppressed, and the properties of the grown crystal can be improved.

In the conventional single crystal pulling apparatus shown in FIG. 17 of Japanese Patent Laid-Open No. 61-222984, the coil 26 causes the surface of the melt portion of the crucible 2 to be equiaxially symmetric and have a radial cusp magnetic field. It has been shown that the properties of the grown crystal can be improved by applying 11a.

Further, the conventional superconducting magnet 110 described in Japanese Patent Laid-Open No. 322408/1988 is shown in FIG.
, The side superconducting coils 101a, 1
01b and center side superconducting coils 102a, 102
The coil structure is divided into four parts of b, and the self magnetic shield 106 is provided around the coil structure. Then, these divided coils are, as shown in FIG. 18, side-side superconducting coils 101a and 101b, center-side superconducting coils 102a and 102b, respectively, connected in series, and these coil pairs are further connected in series, Coil protection elements 103e and 103f are connected in parallel between both ends of each coil pair. Further, a permanent current switch 105 is connected between both ends of the coils connected in series to form a closed circuit. Therefore, since the coils are connected in series to each other at symmetrical positions, the current distribution is symmetrical regardless of which superconducting coil the normal conducting dislocation occurs, so that the unbalanced electromagnetic force is not generated.

[0023]

Since the conventional magnetic field applying type single crystal pulling apparatus is constructed as described above, it has the following problems. In the method of applying the transverse magnetic field in the melt 1, the transverse magnetic field is a non-axisymmetric magnetic field with respect to the axisymmetric thermal convection. Against the effect. Therefore, there has been a problem that non-axial symmetry occurs in the thermal convection, a single crystal having a uniform circular cross section cannot be obtained, and further, the uniformity of crystallinity cannot be obtained in the entire circular cross section. Further, in the method of applying the cusp magnetic field to the melt 1, the cusp magnetic field 11a having an axisymmetric and radial shape is provided in the vicinity of the center of the melt 1 portion of the crucible 2.
Is applied, the thermal convection 8 in the melt 1 is uniformly suppressed, the problem in the method of applying the transverse magnetic field is eliminated, and the property of the grown crystal can be improved. However,
The air-core type coil shown in FIG. 17 has a problem that the leakage magnetic field to the outside of the device is large. A magnetic shield may be provided as a means of reducing the leakage magnetic field, but if the coils are not in symmetrical positions with respect to the magnetic shield, or if the energization currents of the pair of coils are different, the magnetic shield and the coil A large unbalanced electromagnetic force will work between. Therefore, there is a problem that it is difficult to support the coil because it is necessary to increase the size of the structure for supporting the coil cooled to the extremely low temperature. Also, if the coil support structure becomes large in order to support a large electromagnetic force, the amount of heat that penetrates into the coil cooled to a cryogenic temperature via the coil support structure will increase, making it difficult to cool the coil. There was also a problem that the consumption of liquid helium and electric power for the battery would become large.

The present invention has been made in order to solve the above-mentioned problems, and is of a magnetic field application system capable of reducing the unbalanced electromagnetic force acting between the magnetic shield and the coil and achieving simplification of the structure. The purpose is to obtain an apparatus for producing a single crystal.

[0025]

The apparatus for producing a single crystal of a magnetic field application system according to the present invention produces a single crystal by inserting a seed crystal into a single crystal raw material melt filled in a crucible and pulling the crystal. A single crystal pulling apparatus main body, a vacuum container arranged so as to surround the single crystal pulling apparatus main body, and the vacuum so as to surround the single crystal pulling apparatus main body vertically separated from each other. In a magnetic field application type single crystal manufacturing apparatus, which is housed in a container and comprises at least two superconducting coils for applying a cusp magnetic field to the single crystal raw material melt portion, and a magnetic shield installed on the outer periphery of the vacuum container. The at least two superconducting coils are connected in series, and the magnetic shield has upper and lower flange portions that cover the upper and lower end surfaces of the vacuum container and are formed with an inner diameter equal to the central diameter of the superconducting coil.

A magnetic field applying type single crystal manufacturing apparatus according to the present invention is a single crystal pulling apparatus for producing a single crystal by inserting a seed crystal into a single crystal raw material melt filled in a crucible and pulling the crystal. A main body and a vacuum container arranged so as to surround the main body of the single crystal pulling device, and are housed in the vacuum container so as to surround the main body of the single crystal pulling device while being vertically separated from each other, In a magnetic field application type single crystal manufacturing apparatus comprising at least two superconducting coils for applying a cusp magnetic field to the single crystal raw material melt portion, and a magnetic shield installed on the outer periphery of the vacuum container, the at least two superconducting coils The coils are connected in series, and the magnetic shield has upper and lower flange portions that cover the upper and lower end surfaces of the vacuum container and are formed with an inner diameter smaller than the central diameter of the superconducting coil.

A magnetic field application type single crystal manufacturing apparatus according to the present invention is a single crystal pulling apparatus for producing a single crystal by inserting a seed crystal into a single crystal raw material melt filled in a crucible and pulling the crystal. A main body and a vacuum container arranged so as to surround the main body of the single crystal pulling device, and are housed in the vacuum container so as to surround the main body of the single crystal pulling device while being vertically separated from each other, In a magnetic field application type single crystal manufacturing apparatus comprising at least two superconducting coils for applying a cusp magnetic field to the single crystal raw material melt portion, and a magnetic shield installed on the outer periphery of the vacuum container, the at least two superconducting coils The coils are connected in series, and the magnetic shield is formed such that upper and lower flange portions covering the upper and lower end surfaces of the vacuum container are magnetically saturated with respect to a rated magnetic field.

Further, annular end members made of a non-magnetic material are airtightly joined to the upper and lower flange portions of the magnetic shield,
The magnetic shield and the vacuum container are integrally configured.

Further, an annular end member made of the same material as the magnetic shield and made of a thin plate is hermetically joined to the upper and lower flange portions of the magnetic shield to integrally form the magnetic shield and the vacuum container. .

A magnetic field application type single crystal producing apparatus according to the present invention is a single crystal pulling apparatus for producing a single crystal by inserting a seed crystal into a single crystal raw material melt filled in a crucible and pulling the crystal. A main body and a vacuum container arranged so as to surround the main body of the single crystal pulling device, and are housed in the vacuum container so as to surround the main body of the single crystal pulling device while being vertically separated from each other, In a magnetic field application type single crystal manufacturing apparatus comprising at least two superconducting coils for applying a cusp magnetic field to the single crystal raw material melt portion, and a magnetic shield installed on the outer circumference of the vacuum container, the magnetic shield comprises: The upper magnetic shield and the lower magnetic shield are arranged symmetrically with respect to the central horizontal plane.

Further, the cooling / energizing port of the superconducting coil is attached to the vacuum container through between the upper magnetic shield and the lower magnetic shield.

Further, a magnetic shield moving means for adjusting a gap between the upper magnetic shield and the lower magnetic shield is provided.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1. 1 is a cross-sectional view showing the structure of a magnetic field application type single crystal manufacturing apparatus according to Embodiment 1 of the present invention. In the figure, the same parts as those of the conventional single crystal pulling apparatus shown in FIGS. 10 to 19 are designated by the same reference numerals, and the description thereof will be omitted. In the figure, the crystal pulling apparatus main body 100 is
A crucible 2 filled with the melt 1, a heater 3 arranged on the outer periphery of the crucible 2, a pulling apparatus chamber 12 in which the crucible 2 and the heater 3 are housed, and a pulling crystal for pulling a seed crystal 4 at a constant speed. It is composed of the upper drive mechanism 5. The crucible 2 is arranged so as to be located substantially at the axial center of the pulling apparatus chamber 12, and the pulling drive mechanism 5 pulls the seed crystal 4 in the axial direction. A superconducting magnet 200 for applying a cusp magnetic field 11a to the melt 1 is arranged on the outer periphery of the crystal pulling apparatus body 100.

Next, the structure of the superconducting magnet 200 will be described. The vacuum container 17 is made of a non-magnetic material, such as stainless steel, and has a hollow ring shape with a rectangular cross section, and is coaxially arranged on the outer circumference of the crystal pulling apparatus body 100. The superconducting coils 31 and 32 are manufactured to have the same size by winding the same superconducting element wire in a ring shape with the same number of turns. Then, the superconducting coils 31 and 32 are coaxially arranged on the outer circumference of the crystal pulling apparatus main body 100 so as to face the upper and lower sides of the crucible 2 in the vacuum container 17, and are connected in series. Further, the superconducting coils 31 and 32 are respectively supported by the support member 42 on the inner wall surface of the vacuum container 17 in the axial direction, that is, in the vertical direction, and by the support member 41 on the inner wall surface of the vacuum container 17 in the radial direction, that is, the horizontal direction. It is supported. Furthermore, the support member 43 is the superconducting coil 31,
The space between 32 is supported vertically. These support members 4
A plurality of 1, 42, 43 are provided at predetermined intervals in the circumferential direction. The magnetic shield 40 is made of a magnetic material, for example, pure iron, into a ring shape having a U-shaped cross section.
It is arranged so as to surround the outer circumference of 7. In the magnetic shield 40, the inner diameters of the upper and lower flange portions 40a are equal to the central diameters of the superconducting coils 31 and 32. Although not shown, the superconducting magnet 200 is provided in the vacuum container 17 to suppress heat from entering the coil portion, and in the vacuum container 17 to cool the heat shield and the coil. It is equipped with a cooling mechanism such as a small refrigerator and a current lead for energizing the coil. The center diameter of the coil referred to here corresponds to the center diameter between the inner diameter and the outer diameter of the coil, that is, (coil inner diameter + coil outer diameter) / 2.

Next, the operation of the single crystal manufacturing apparatus thus configured will be described. By heating the heater 3,
The single crystal raw material, such as silicon, contained in the crucible 2 is melted. Then, the impurities 9 are dissolved in the melt 1 from the inner surface of the crucible 2 in contact with the high-temperature silicon melt 1. Further, thermal convection 8 is induced in the melt 1 by heating the heater 3. On the other hand, the superconducting coils 31 and 32 are cooled to a cryogenic temperature by a small refrigerator (not shown), and current is passed through current leads (not shown). Then, a radial cusp magnetic field 11a is applied to the melt 1 in an equiaxial symmetry. Since the superconducting coils 31 and 32 have the same number of turns and the same dimensions, the same magnetomotive force is generated. The thermal convection 8 induced by the heating of the heater 3 is suppressed in the magnitude of the convection due to the magnetic resistance generated by the cusp magnetic field 11a. Therefore, the impurities 9 dissolved in the melt 1 from the inner surface of the crucible 2 stay on the inner surface side of the crucible 2 and the dispersion of the melt 1 in the entire inside is suppressed. Furthermore, temperature fluctuations in the solid-liquid interface boundary layer 6 due to the thermal convection 8 are suppressed. Therefore, a factor that deteriorates the quality of the single crystal is suppressed, and a high quality single crystal can be manufactured with high yield.

Here, the position and the value of the cusp magnetic field 11a which are optimum for manufacturing the crystal are selected by simulation or experiment. Further, the magnetic field generated by the superconducting coils 31 and 32 only needs to act on the melt 1, and is preferably as small as possible in other regions. The magnetic shield 40 suppresses the magnetic field leaking from the superconducting magnet to the outside and reduces the necessary magnetomotive force for the magnetic field required for the melt 1.

Between the superconducting coil 31 and the magnetic shield 40, in a typical example, an electromagnetic force of several thousand kgf (attracting force attracting each other) acts. Similarly, an electromagnetic force in the opposite direction acts between the superconducting coil 32 and the magnetic shield 40 with the same value. Since the superconducting coils 31 and 32 are fixed to each other by the supporting member 43, as long as the coils are symmetrical with respect to the magnetic shield 40, the force acting on the structure including the superconducting coils 31 and 32 and the supporting member 43 is It becomes 0. Since the superconducting coils 31 and 32 are cooled to a low temperature in order to make them superconducting, the support member 43 is also cooled to a low temperature. Therefore, the support member 43 supports the superconducting coils 31 and 32 from the room temperature portion.
Unlike the above, a sufficiently strong support member can be obtained.
However, since the supporting members 41 and 42 support the superconducting coils 31 and 32 cooled to a low temperature from the room temperature portion, the supporting members 41 and 42 are sufficiently thin so as not to impair the cooling performance of the coils and have a small amount of heat penetration. There is a need to.

In this type of superconducting magnet, as described above, as pointed out in Japanese Patent Laid-Open No. 322408/1988, it is known that an unbalanced electromagnetic force is generated due to the displacement of the coil. Has been. Therefore, in order to make the support members 41, 42 thin, the superconducting coil 3
It is also necessary to reduce the weight of the parts cooled to a low temperature, such as 1, 32 and the support member 43, and to reduce the unbalanced electromagnetic force caused by the displacement of the superconducting coils 31, 32.

Here, the superconducting magnet in which the superconducting coils 31 and 32 are displaced in the axial direction (vertical direction) and the superconducting magnet in which the superconducting coils 31 and 32 are displaced in the radial direction (horizontal direction). 2, the inner diameter (diameter) of the flange portion 40a of the magnetic shield 40 was changed, and the unbalanced electromagnetic force generated between the coil and the magnetic shield was measured. The result is shown in FIG. In addition, in FIG. 2, the horizontal axis represents the inner diameter of the flange portion 40a, the vertical axis represents the unbalanced electromagnetic force, and the curve A represents the unbalanced electromagnetic force in the superconducting magnet that is displaced in the axial direction. B indicates the unbalanced electromagnetic force in the superconducting magnet that is displaced in the radial direction. It can be seen from FIG. 2 that the unbalanced electromagnetic force is affected by the inner diameter of the flange portion 40a of the magnetic shield 40. Then, the flange portion 40 against the generated unbalanced electromagnetic force is different between when the coil is displaced in the axial direction and when it is displaced in the radial direction.
It can be seen that the effect of the inner diameter of a acts in reverse. Therefore,
When the coils are displaced in the axial direction and the radial direction, it can be seen that the unbalanced electromagnetic force generated can be minimized by matching the inner diameter of the flange portion 40a with the center diameter of the coil.

In the first embodiment, the magnetic shield 40
Since the inner diameter of the flange portion 40a is matched with the center diameter of the superconducting coils 31 and 32, the unbalanced electromagnetic force caused by the positional deviation of the coils can be reduced. Moreover, since the superconducting coils 31 and 32 are connected in series, the distribution of the current flowing through the coils is symmetrical, and the generation of unbalanced electromagnetic force due to the fluctuation of the current distribution is suppressed. Therefore, the support members 41, 4
2 can be made thin, heat intrusion through the supporting members 41, 42 is suppressed, and a high-performance single crystal manufacturing apparatus with cooling characteristics can be obtained.

Embodiment 2. FIG. 3 is a sectional view showing the structure of a magnetic field application type single crystal manufacturing apparatus according to Embodiment 2 of the present invention. In the second embodiment, the magnetic shield 4
The thicknesses of the upper and lower flange portions 40a of 0 are reduced so that the inner diameter of the flange portion 40a matches the inner diameter of the vacuum container 17, and the other configurations are the same as those of the first embodiment. According to the second embodiment, the upper and lower flange portions 40
The thickness of a is designed to be magnetically saturated with respect to the rated cusp magnetic field 11a. Therefore, even if the superconducting coils 31 and 32 are displaced, the unbalanced electromagnetic force acting between the magnetic shield 40 and the superconducting coils 31 and 32 can be minimized. Therefore, also in the second embodiment, the same effect as in the first embodiment can be obtained.

Embodiment 3. FIG. 4 is a sectional view showing the structure of a magnetic field application type single crystal manufacturing apparatus according to Embodiment 3 of the present invention. In the third embodiment, the magnetic shield 4
The inner diameters of the upper and lower flange portions 40a of 0 are made equal to the inner diameter of the vacuum container 17, and the support member 41 is omitted. Other configurations are the same as those in the first embodiment. According to the third embodiment, the inner diameter of the flange portion 40a extends to the inner diameter position of the vacuum container 17. It can be seen from the curve B in FIG. 2 that when the coil is displaced in the radial direction, a force that suppresses the displacement, that is, a force that returns the coil to the symmetrical position acts on the coil. Therefore, it is possible to omit the supporting member 41 that supports the coil in the horizontal direction, and it is possible to further suppress heat intrusion from the room temperature portion into the coil portion.

Fourth Embodiment FIG. 5 is a sectional view showing the configuration of a magnetic field application type single crystal manufacturing apparatus according to Embodiment 4 of the present invention. In the fourth embodiment, a ring-shaped end member 17a having a U-shaped cross section with a non-magnetic material, such as stainless steel, is used as the upper and lower flange portions 40a of the magnetic shield 40. It is joined and integrated with the inner peripheral edge portion by welding 44, and other configurations are the same as those in the first embodiment. According to the fourth embodiment, since the magnetic shield 40 and the end member 17a which are joined and integrated by the welding 44 function as a vacuum container,
The outer peripheral portion of the vacuum container 17 required in the first embodiment can be omitted, and the size and weight of the device and the cost can be reduced. Although the fourth embodiment is applied to the single crystal manufacturing apparatus of the first embodiment, the same effect can be obtained even when applied to the single crystal manufacturing apparatus of the second and third embodiments. .

Embodiment 5. In the fourth embodiment described above, the vacuum container is configured by integrally joining the end member 17a made of the non-magnetic material and the magnetic shield 40 made of the magnetic material by welding. However, in the fifth embodiment, FIG. , The end member 17b is made of the same magnetic material as the magnetic shield 40 with a sufficiently thin thickness.
b and the magnetic shield 40 are joined and integrated by welding to form a vacuum container. According to the fifth embodiment, the magnetic material is used for the end member 17b,
Since it is made thin enough, the superconducting coils 31, 32
The magnetic field generated in 1 is applied to the melt 1 and does not hinder the suppression of the size of the thermal convection 8. On the other hand, since the magnetic shield 40 is made sufficiently thick as in the fourth embodiment, a sufficient shielding effect can be obtained. Therefore,
The outer peripheral portion of the vacuum container 17 can be omitted, and the size and weight of the device and the cost can be reduced.

Sixth Embodiment FIG. 7 is a sectional view showing the structure of a magnetic field application type single crystal manufacturing apparatus according to Embodiment 6 of the present invention. In the sixth embodiment, the upper and lower magnetic shields 40A, 40B made of a magnetic material, for example, pure iron, in a ring shape having an L-shaped cross section face each other while being separated by a predetermined distance in the axial direction. That is, they are arranged so as to surround the outer circumference of the vacuum container 17 symmetrically with respect to the central horizontal plane. Then, the upper and lower magnetic shields 40A, 4
The inner diameter of each flange portion 40a of 0B matches the center diameter of the coil. That is, the upper and lower magnetic shields 40
A and 40B are superconducting coils 31 of the magnetic shield 40,
It corresponds to a portion surrounding 32. The rest of the configuration is similar to that of the first embodiment. In the sixth embodiment, since the upper and lower magnetic shields 40A and 40B are arranged facing each other with a predetermined distance in the axial direction, a gap is formed between the upper and lower magnetic shields 40A and 40B. Has occurred. However, the amount of magnetic force lines passing through the gap is small, and the magnetic shield effect is hardly affected. Therefore, in the divided upper and lower magnetic shields 40A and 40B, the gap between the upper and lower magnetic shields 40A and 40B can be omitted as compared with the magnetic shield 40, and the weight of the superconducting magnet 200 can be reduced accordingly.

Embodiment 7. In the seventh embodiment, as shown in FIG. 8, the cooling / energizing port 45 is provided in the vacuum container 17 through the gap between the upper and lower magnetic shields 40A and 40B. The other structure is the same as that of the sixth embodiment. According to the seventh embodiment, the cooling / energizing port 45 for taking out piping / wiring required for cooling / energizing the superconducting coils 31 and 32 is horizontally extended from between the upper and lower magnetic shields 40A and 40B. Therefore, the height dimension of the superconducting magnet 200 can be reduced.

Embodiment 8. In the eighth embodiment, as shown in FIG. 9, a jack bolt 46 as a magnetic shield moving means includes a pair of upper and lower magnetic shields 40.
It is arranged between A and 40B. The other structure is the same as that of the sixth embodiment. According to the eighth embodiment, the gap between the upper and lower magnetic shields 40A and 40B can be adjusted by the jack bolt 46. Therefore, the upper and lower magnetic shields 40A,
By adjusting the gap between 40B, the cusp magnetic field 11
The distribution of a can be finely adjusted, and the thermal convection 8 can be efficiently suppressed. The magnetic shield moving means is not limited to the jack bolt 46, but may be a hydraulic drive mechanism.

[0048]

Since the present invention is constituted as described above, it has the following effects.

According to the present invention, a single crystal pulling apparatus main body for producing a single crystal by inserting a seed crystal into a single crystal raw material melt filled in a crucible, and pulling the single crystal pulling apparatus main body A vacuum container arranged so as to surround the apparatus main body, and is housed in the vacuum container so as to surround the single crystal pulling apparatus main body while being vertically separated from each other. In a magnetic field application type single crystal manufacturing apparatus comprising at least two superconducting coils for applying a cusp magnetic field and a magnetic shield installed on the outer periphery of the vacuum container, the at least two superconducting coils are connected in series, Since the upper and lower flanges of the magnetic shield that cover the upper and lower end surfaces of the vacuum container are formed to have an inner diameter equal to the central diameter of the superconducting coil, the unbalanced electromagnetic generated due to the displacement of the superconducting coil is generated. The can be reduced, simplifying the support structure of the superconducting coil is reduced, the amount of heat penetration is reduced, it is possible to obtain a single crystal manufacturing apparatus of high performance magnetic field application method for cooling characteristics.

According to the present invention, a single crystal pulling apparatus main body for producing a single crystal by inserting a seed crystal into the single crystal raw material melt filled in the crucible and pulling the crystal, and the single crystal pulling apparatus A vacuum container arranged so as to surround the apparatus main body, and is housed in the vacuum container so as to surround the single crystal pulling apparatus main body while being vertically separated from each other. In a magnetic field application type single crystal manufacturing apparatus comprising at least two superconducting coils for applying a cusp magnetic field and a magnetic shield installed on the outer periphery of the vacuum container, the at least two superconducting coils are connected in series, Since the upper and lower flanges of the magnetic shield that cover the upper and lower end surfaces of the vacuum container are formed to have an inner diameter smaller than the central diameter of the superconducting coil, the magnetic shield is generated due to the horizontal displacement of the superconducting coil. Unbalanced electromagnetic force acts to return the superconducting coils symmetrically positioned, enables the small-diameter reduction or omission of the support member for supporting the superconducting coil in a horizontal direction,
The structure can be simplified and the amount of heat penetration can be reduced.
It is possible to obtain a high-performance magnetic field application type single crystal manufacturing apparatus with high cooling performance.

According to the present invention, a single crystal pulling apparatus main body for producing a single crystal by inserting a seed crystal into a single crystal raw material melt filled in a crucible and pulling this crystal, and the single crystal pulling apparatus main body A vacuum container arranged so as to surround the apparatus main body, and is housed in the vacuum container so as to surround the single crystal pulling apparatus main body while being vertically separated from each other. In a magnetic field application type single crystal manufacturing apparatus comprising at least two superconducting coils for applying a cusp magnetic field and a magnetic shield installed on the outer periphery of the vacuum container, the at least two superconducting coils are connected in series, Since the upper and lower flanges of the magnetic shield that cover the upper and lower end surfaces of the vacuum container are formed to a thickness that magnetically saturates against the rated magnetic field, the imbalance that occurs due to the displacement of the superconducting coil Magnetic force can be reduced, simplifying the support structure of the superconducting coil is reduced, the amount of heat penetration is reduced,
It is possible to obtain a magnetic field application type single crystal manufacturing apparatus having a high performance of cooling characteristics and a small height dimension of a superconducting magnet.

Further, annular end members made of a non-magnetic material are airtightly joined to the upper and lower flange portions of the magnetic shield,
Since the magnetic shield and the vacuum container are integrally formed, the outer peripheral portion of the vacuum container is omitted, and the size and weight are reduced and the cost is reduced.

Further, since the annular end members made of the same material as the magnetic shield and made of a thin plate are hermetically joined to the upper and lower flange portions of the magnetic shield, the magnetic shield and the vacuum container are integrally formed, so that the vacuum Since the outer peripheral part of the container can be omitted, the size and weight can be reduced and the cost can be reduced.

According to the present invention, a single crystal pulling apparatus main body for producing a single crystal by inserting a seed crystal into a single crystal raw material melt filled in a crucible, and pulling the single crystal pulling apparatus main body A vacuum container arranged so as to surround the apparatus main body, and is housed in the vacuum container so as to surround the single crystal pulling apparatus main body while being vertically separated from each other. In a magnetic field application type single crystal manufacturing apparatus comprising at least two superconducting coils for applying a cusp magnetic field and a magnetic shield installed on the outer circumference of the vacuum container, the magnetic shields are arranged symmetrically with respect to a central horizontal plane. Since it is composed of the upper magnetic shield and the lower magnetic shield, a light-weight magnetic field applying system single crystal manufacturing apparatus can be obtained.

Further, since the cooling / energizing port of the superconducting coil is attached to the vacuum container through between the upper magnetic shield and the lower magnetic shield, the height of the superconducting magnet can be reduced. .

Further, since the magnetic shield moving means for adjusting the gap between the upper magnetic shield and the lower magnetic shield is provided, the magnetic field distribution can be finely adjusted and the thermal convection can be effectively suppressed.

[Brief description of drawings]

FIG. 1 is a sectional view showing a single crystal manufacturing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a change in an unbalanced electromagnetic force caused by a positional deviation of a superconducting coil with respect to an inner diameter of a flange portion of a magnetic shield.

FIG. 3 is a sectional view showing a single crystal manufacturing apparatus according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a single crystal manufacturing apparatus according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing a single crystal manufacturing apparatus according to Embodiment 4 of the present invention.

FIG. 6 is a sectional view showing a single crystal manufacturing apparatus according to Embodiment 5 of the present invention.

FIG. 7 is a sectional view showing a single crystal manufacturing apparatus according to Embodiment 6 of the present invention.

FIG. 8 is a sectional view showing a single crystal manufacturing apparatus according to Embodiment 7 of the present invention.

FIG. 9 is a sectional view showing a single crystal manufacturing apparatus according to Embodiment 8 of the present invention.

FIG. 10 is a configuration diagram showing a conventional single crystal pulling apparatus.

FIG. 11 is a configuration diagram showing a conventional transverse magnetic field applying system single crystal pulling apparatus.

FIG. 12 is a structural view of a conventional single crystal pulling apparatus of a transverse magnetic field applying type using a superconducting magnet apparatus as seen from the front direction.

FIG. 13 is a configuration view of a conventional single crystal pulling apparatus of a transverse magnetic field applying system using a superconducting magnet apparatus as viewed from the top surface direction.

FIG. 14 is a configuration diagram of another example of a conventional single crystal pulling apparatus of a transverse magnetic field applying system using a superconducting magnet apparatus as viewed from the front direction.

FIG. 15 is a configuration view of another example of a conventional single crystal pulling apparatus of a transverse magnetic field applying system using a superconducting magnet apparatus as viewed from the top surface direction.

FIG. 16 is a diagram illustrating a conventional cusp magnetic field application type single crystal pulling apparatus.

FIG. 17 is a diagram for explaining another example of the conventional single crystal pulling apparatus of the cusp magnetic field applying system.

FIG. 18 is a connection diagram showing an example of connection in a conventional superconducting magnet device.

FIG. 19 is a sectional view showing a coil arrangement in a conventional superconducting magnet device.

[Explanation of symbols]

1 melt of single crystal raw material, 2 crucible, 4 seed crystal, 7 single crystal, 17 vacuum container, 17a, 17b end member, 3
1, 32 superconducting coil, 40 magnetic shield, 40a
Flange portion, 40A upper magnetic shield, 40B lower magnetic shield, 45 cooling / energizing port, 46 jack bolt (magnetic shield moving means), 100 single crystal pulling apparatus main body.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A 64-33093 (JP, A) JP-A 10-167875 (JP, A) JP-A 10-279394 (JP, A) JP-A 58- 217493 (JP, A) JP 61-222984 (JP, A) JP 63-222408 (JP, A) JP 8-333190 (JP, A) JP 10-120485 (JP, A) Japanese Patent Publication No. 3-61630 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) C30B 1/00-35/00

Claims (8)

(57) [Claims] 1. A single crystal pulling apparatus main body for producing a single crystal by inserting a seed crystal into a single crystal raw material melt filled in a crucible and surrounding the single crystal pulling apparatus main body. And a vacuum container arranged so as to be vertically separated from each other and housed in the vacuum container so as to surround the main body of the single crystal pulling apparatus, and apply a cusp magnetic field to the single crystal raw material melt portion. In a magnetic field application type single crystal manufacturing apparatus comprising at least two superconducting coils and a magnetic shield installed on the outer periphery of the vacuum container, the at least two superconducting coils are connected in series, and the magnetic shield is An apparatus for producing a single crystal by a magnetic field application method, wherein upper and lower flange portions covering upper and lower end surfaces of a vacuum container are formed to have an inner diameter equal to a central diameter of the superconducting coil. 2. A single crystal pulling apparatus main body for producing a single crystal by inserting a seed crystal into a single crystal raw material melt filled in a crucible and surrounding the single crystal pulling apparatus main body. And a vacuum container arranged so as to be vertically separated from each other and housed in the vacuum container so as to surround the main body of the single crystal pulling apparatus, and apply a cusp magnetic field to the single crystal raw material melt portion. In a magnetic field application type single crystal manufacturing apparatus comprising at least two superconducting coils and a magnetic shield installed on the outer periphery of the vacuum container, the at least two superconducting coils are connected in series, and the magnetic shield is An apparatus for producing a single crystal by a magnetic field application method, wherein upper and lower flange portions that cover upper and lower end surfaces of a vacuum container are formed with an inner diameter smaller than a central diameter of the superconducting coil. 3. A single crystal pulling apparatus main body for producing a single crystal by inserting a seed crystal into a single crystal raw material melt filled in a crucible and surrounding the single crystal pulling apparatus main body. And a vacuum container arranged so as to be vertically separated from each other and housed in the vacuum container so as to surround the main body of the single crystal pulling apparatus, and apply a cusp magnetic field to the single crystal raw material melt portion. In a magnetic field application type single crystal manufacturing apparatus comprising at least two superconducting coils and a magnetic shield installed on the outer periphery of the vacuum container, the at least two superconducting coils are connected in series, and the magnetic shield is An apparatus for producing a single crystal by a magnetic field application method, wherein upper and lower flange portions that cover upper and lower end surfaces of a vacuum container are formed to have a thickness that is magnetically saturated with respect to a rated magnetic field. 4. The magnetic shield and the vacuum container are integrally formed by air-tightly joining annular end members made of a non-magnetic material to the upper and lower flange portions of the magnetic shield. A magnetic field application type single crystal manufacturing apparatus according to claim 3. 5. A magnetic shield and a vacuum container are integrally formed by air-tightly joining annular end members made of a thin plate of the same material as the magnetic shield to upper and lower flange portions of the magnetic shield. The magnetic field applying system single crystal manufacturing apparatus according to claim 1. 6. A single crystal pulling apparatus main body for producing a single crystal by inserting a seed crystal into a single crystal raw material melt filled in a crucible and surrounding the single crystal pulling apparatus main body. And a vacuum container arranged so as to be vertically separated from each other and housed in the vacuum container so as to surround the main body of the single crystal pulling apparatus, and apply a cusp magnetic field to the single crystal raw material melt portion. In a magnetic field application type single crystal manufacturing apparatus comprising at least two superconducting coils and a magnetic shield installed on the outer periphery of the vacuum container, the magnetic shield is an upper magnetic field symmetrically arranged with respect to a central horizontal plane. A magnetic field application type single crystal manufacturing apparatus comprising a shield and a lower magnetic shield. 7. A cooling / energizing port for a superconducting coil,
7. The vacuum container is attached through a space between the upper magnetic shield and the lower magnetic shield.
A magnetic field application type single crystal manufacturing apparatus as described. 8. The magnetic field applying single crystal manufacturing apparatus according to claim 6, further comprising a magnetic shield moving means for adjusting a gap between the upper magnetic shield and the lower magnetic shield.