JP2013193946A - Superconducting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superconducting device for single crystal pulling units which decreases the space of the peripheral devices of a superconducting electric magnet to current superconducting electric magnet of the same size.SOLUTION: A superconducting electric magnet 10A for single crystal pulling units is provided with a plurality of cooling vessels 13 containing a superconducting coil 11 which is cooled with a coolant, respective cooling vessels 13 are connected with each other via a communicating tube 14 and the communicating tube 14 is configured to enable the coolant supplied from a cooling device 20 to be supplied to each cooling vessel 13.

Description

  The present invention relates to a superconducting device, and more particularly, to a superconducting device for a single crystal pulling device that suppresses melt convection by applying a magnetic field in the single crystal pulling device.

  In the semiconductor field that supports IT technology, semiconductor wafers such as silicon (Si) and gallium arsenide (GaAs) are listed as the base material. Although these semiconductor materials were originally manufactured with a small diameter, the large diameter has been advanced in the demand for further high integration and high functionality in semiconductor devices, and mass and inexpensive production thereof.

  In manufacturing a large-diameter silicon single crystal, it is a very important technique to suppress melt convection in a crucible that causes crystal defects during the growth process. Currently, a single crystal refining apparatus using a method called Cz method (chocoral ski method) as a technique for suppressing melt convection has been developed and manufactured.

  In the Cz method, when the crystallized material is pulled up from the molten raw material, a Helmholtz superconducting magnet arranged so as to face each other with the molten raw material sandwiched therebetween is used in the crucible in a direction transverse to the pulling direction. This is a method for producing a large-diameter and high-quality semiconductor by generating a strong magnetic field and thereby suppressing thermal convection of the solution.

  In addition, in order to meet the demand for higher capacity, lower cost and higher quality of semiconductor devices, the pulling of silicon single crystals has been increased to 8 inches and 12 inches. Accordingly, a superconducting electromagnet that can generate a magnetic field in a large space is desired.

  On the other hand, superconducting electromagnets capable of generating a magnetic field in a large space tend to be large, and there is a problem that the single crystal pulling device is large and expensive. In addition, superconducting electromagnets that can generate a magnetic field in a large space cannot ignore the effects of external leakage magnetic fields, and are required per crucible to avoid the effects of leakage magnetic fields on the human body and peripheral equipment. There is also a problem that the area to be increased becomes large.

  Against this background, various techniques have been proposed in order to save space and reduce the price of a superconducting electromagnet applied to a single crystal pulling apparatus or a single crystal pulling apparatus. For example, Japanese Patent Application Laid-Open No. 10-139599 (Patent Document 1) describes a superconducting magnet that requires only N + 1 superconducting coils when the number of lifting furnaces is N (N is a natural number).

JP-A-10-139599

  In conventional techniques such as the technique described in Patent Document 1, one power supply and cooling facility, which is a peripheral device of a superconducting electromagnet, is installed for each superconducting electromagnet. In addition, as described above, since the superconducting electromagnet tends to increase in size when responding to a request for generating a magnetic field in a large space, the same applies to the power supply and cooling equipment that are peripheral devices as the superconducting electromagnet increases in size. Tend to be larger.

  However, there is a demand for space saving of a superconducting electromagnet applied to a single crystal pulling device or a single crystal pulling device while generating a magnetic field in a large space, and a power supply and a cooling facility that are peripheral devices of the superconducting magnet It is desired that the space required for this is kept as small as possible.

  Further, from the viewpoint of price, as the superconducting electromagnet becomes larger, the attractive force generated between the superconducting coils and the leakage magnetic field to the surroundings cannot be ignored. In particular, with respect to the leakage magnetic field, the area of the safety area required for an area of 50 gauss or more, such as the European standard, will increase several times as the expected size of the apparatus increases to 18 inches. . For this reason, it is necessary to further secure a strong mechanical support and a surrounding space to cope with the attractive force generated between the superconducting coils and the leakage magnetic field with respect to the surroundings.

  The present invention has been made in view of the above circumstances, and provides a superconducting device for a single crystal pulling apparatus that reduces the space for peripheral devices of a superconducting magnet relative to a superconducting magnet of the same size as a conventional one. For the purpose.

  In order to solve the above-described problem, a superconducting device according to an embodiment of the present invention includes a plurality of cooling containers that contain superconducting coils that are cooled by a refrigerant, and the cooling containers are connected by a communication pipe, and the communication The pipe is configured to be able to supply a coolant supplied from a cooling facility to each of the cooling containers.

  ADVANTAGE OF THE INVENTION According to this invention, the space of peripheral devices, such as a power supply of superconducting electromagnet and cooling equipment, can be reduced.

The longitudinal cross-sectional view which shows the structure of the superconducting electromagnet for single crystal pulling apparatuses which concerns on the 1st Embodiment of this invention. The top view which shows the structure of the superconducting electromagnet for single crystal pulling apparatuses which concerns on the 2nd Embodiment of this invention. The top view which shows the structure of the superconducting electromagnet for single crystal pulling apparatuses which concerns on the 3rd Embodiment of this invention. The top view which shows the structure of the superconducting electromagnet for single crystal pulling apparatuses which concerns on the 4th Embodiment of this invention.

  Hereinafter, superconducting devices according to embodiments of the present invention will be described with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a longitudinal sectional view showing a configuration of a first superconducting electromagnet 10A for a single crystal pulling apparatus, which is an example of a superconducting apparatus according to the first embodiment of the present invention.

  The superconducting electromagnet 10A for the first single crystal pulling apparatus includes, for example, a plurality of cryostats 13 (13a to 13e) as cooling containers for accommodating therein the refrigerant container 12 in which the superconducting coil 11 is immersed in the refrigerant. The refrigerant containers 12 of the plurality of cryostats 13 a to 13 e are communicated by a communication pipe 14. The configuration inside each cryostat 13 is the same as that of a conventional cryostat except that the cryostats 13 are connected by the communication pipe 14.

  The communication pipe 14 has a heat insulating structure and is configured to be able to supply a refrigerant to each of the refrigerant containers 12. The heat insulating structure of the communication pipe 14 serves as a radiation shield. Superconducting coil 11 is reinforced with a reinforcing ring.

  Further, in the first superconducting electromagnet 10A for single crystal pulling apparatus, magnetic bodies 18 constituted by blocks or plates are installed on the end portions of the cryostats 13a and 13e located at both ends.

  In the first superconducting electromagnet 10A for single crystal pulling apparatus, a set of power supply equipment 19 and cooling equipment 20 are connected to the communication pipe 14. The cooling facility 20 that operates by receiving power supply from the power supply facility 19 supplies the refrigerant to the communication pipe 14 and cools the superconducting coil 11 in each cryostat 13 (13a to 13e).

  In the single crystal pulling apparatus to which the first single crystal pulling apparatus superconducting magnet 10A is applied, the pulling furnace 1 is disposed between each superconducting coil 11 (cryostat 13) of the first single crystal pulling apparatus superconducting magnet 10A. . In the pulling furnace 1, the semiconductor material 4 is melted inside the crucible 3 by the heat from the heater 2 installed in the pulling furnace 1.

  The thermal convection induced by the heating of the heater 2 is suppressed by a transverse magnetic field generated by a pair of superconducting coils 11 placed so as to face each other with the crucible 3 interposed therebetween, and the direction of the inserted seed crystal (in FIG. 1) A high quality single crystal grows in the solid-liquid boundary layer as it is pulled upward.

  According to the superconducting electromagnet 10A for the first single crystal pulling apparatus configured as described above, the superconducting coil 11 in the plurality of cryostats 13 (13a to 13e) is cooled by the one set of power supply equipment 19 and cooling equipment 20. Therefore, a plurality of pulling furnaces 1 can be operated.

  As a result, in the conventional single crystal pulling apparatus, the power supply equipment 19 and the cooling equipment 20 that are installed one by one for each crucible 3 apply the first superconducting electromagnet 10A for single crystal pulling apparatus. In the single crystal pulling apparatus, the power supply equipment 19 and the cooling equipment 20 can be converged one by one as the whole apparatus, and the power supply equipment 19 and the cooling equipment 20 can be largely eliminated.

  Further, by installing the magnetic body 18 at both ends of the superconducting electromagnet 10A for the first single crystal pulling apparatus, it is possible to suppress the attractive force and the leakage magnetic field generated by the excitation.

  In FIG. 1, as an example, the communication pipe 14 and the cooling equipment 20 are connected at a position outside the cryostat 13 a located at the extreme end of the multiple cryostats 13 a to 13 e. 1 is not limited to the position illustrated in FIG. 1, and can be communicated at any position of the refrigerant flow path constituted by the communication pipe 14 as long as the refrigerant supplied from the cooling facility 20 can circulate through the communication pipe 14. The pipe | tube 14 and the cooling equipment 20 should just be connected.

[Second Embodiment]
FIG. 2 is a top view showing a configuration of a second superconducting electromagnet 10B for a single crystal pulling apparatus, which is an example of the superconducting apparatus according to the second embodiment of the present invention.

  The second superconducting electromagnet 10B for the single crystal pulling apparatus is different from the first superconducting electromagnet 10A for the single crystal pulling apparatus by removing the magnetic bodies 18 at both ends and separating the cryostat 13 containing the superconducting coil 11 in an annular shape. The communication pipes 14 are connected in an annular shape.

  According to the second single-crystal pulling apparatus superconducting magnet 10B configured as described above, in addition to the same effects as the first single-crystal pulling apparatus superconducting magnet 10A, the cryostat 13 housing the superconducting coil 11 is provided. In the conventional and first superconducting electromagnet 10A for the single crystal pulling apparatus, N + 1 superconducting coils 11 are required for the pulling furnace 1 having N installed (N is a natural number). This can be replaced with N superconducting coils 11.

  Further, according to the second single-crystal pulling apparatus superconducting magnet 10B, the attractive force caused by the superconducting coil 11 can be obtained without the magnetic bodies 18 arranged at both ends of the first single-crystal pulling apparatus superconducting magnet 10A. Can be offset. Therefore, a person can enter the space inside the communication pipe 14 connected in an annular shape, and can be used effectively by, for example, arranging the maintenance area of the apparatus, the cooling facility 20 or the like.

  In addition, in FIG. 2, although the example of the 2nd superconducting electromagnet 10B for single crystal pulling apparatuses arrange | positioned as an example on the outer peripheral side of the communication pipe 14 to which the cooling facility 20 is connected in an annular shape is shown. The cooling facility 20 may be disposed on the inner peripheral side of the communication pipe 14.

[Third Embodiment]
FIG. 3 is a top view showing a configuration of a third superconducting electromagnet 10C for a single crystal pulling apparatus which is an example of the superconducting apparatus according to the third embodiment of the present invention.

  For example, as shown in FIG. 3, the third single-crystal pulling apparatus superconducting magnet 10 </ b> C is formed at the center of each superconducting coil 11 of the second single-crystal pulling apparatus superconducting magnet 10 </ b> B configured to be connected in an annular shape. Further, a magnetic field correcting iron core 23 is further arranged.

  According to the third superconducting electromagnet 10C for single crystal pulling apparatus configured as described above, the same effect as that of the second superconducting electromagnet 10B for single crystal pulling apparatus is obtained, and in addition, the cryostat 13 housing the superconducting coil 11 is provided. It is possible to suppress the gradient of the magnetic field in the radial direction in the crucible 3 that occurs when the is placed in an annular shape. That is, the magnetic field gradient in the radial direction can be corrected and a flat transverse magnetic field can be maintained.

  In addition, in FIG. 3, although the example of the 3rd superconducting electromagnet 10C for single crystal pulling apparatuses arrange | positioned on the outer peripheral side of the communicating pipe 14 to which the cooling facility 20 is connected to an annular shape is shown as an example, The cooling facility 20 may be disposed on the inner peripheral side of the communication pipe 14.

[Fourth Embodiment]
FIG. 4 is a top view showing a configuration of a fourth superconducting electromagnet 10D for a single crystal pulling apparatus as an example of the superconducting apparatus according to the fourth embodiment of the present invention.

  For example, as shown in FIG. 4, the fourth single crystal pulling apparatus superconducting magnet 10 </ b> D includes the first single crystal pulling apparatus superconducting magnet 10 </ b> A in two semicircular arcs at both ends of two parallel straight lines. Arranged in a connected shape (so-called racetrack shape).

  The fourth single-crystal pulling apparatus superconducting magnet 10D configured as described above has the same effects as the first single-crystal pulling apparatus superconducting magnet 10A, and in addition, for the conventional and first single-crystal pulling apparatus. Compared to the superconducting electromagnet 10A, a space-saving and highly efficient apparatus system can be constructed.

  FIG. 4 shows an example of a fourth superconducting electromagnet 10D for a single crystal pulling apparatus arranged on the outer peripheral side of the communication pipe 14 to which the cooling facility 20 is connected in a racetrack shape as an example. The cooling facility 20 may be disposed on the inner peripheral side of the communication pipe 14.

  Also, in FIG. 4, as an example, a fourth single crystal in which the same number of cryostats 13 are arranged to face each other at two straight portions of the communication pipe 14 connected in a racetrack shape. Although an example of the superconducting electromagnet 10D for the lifting device is shown, the number of the cryostats 13 is not necessarily the same. For example, one may be four and the other may be five.

  As described above, according to the superconducting electromagnets 10A to 10D for the first to fourth single crystal pulling apparatuses, one cooling facility for supplying cold to a cryostat as a cooling vessel for cooling the superconducting coil and one power supply facility for each. (1 set) can be converged, and cooling equipment and power supply equipment can be greatly reduced.

  Further, in the first to fourth single-crystal pulling apparatus superconducting magnets 10A to 10D, the leakage magnetic field can be suppressed by the arrangement of the magnetic body, etc., so that a constant magnetic field is obtained as compared with the conventional single-crystal pulling apparatus superconducting magnet. It is possible to greatly reduce the above-mentioned space where entry is prohibited. Therefore, the space for preventing entry of a certain magnetic field or more and the first to fourth superconducting magnets 10A to 10D for the single crystal pulling apparatus, which are required to be secured in the single crystal pulling apparatus to which the conventional single crystal pulling apparatus superconducting magnet is applied, are applied. A space that is different from a space that is not allowed to enter beyond a certain magnetic field that must be secured by the single crystal pulling apparatus can be used effectively, and the work can be made more efficient.

  Further, in the second and third superconducting electromagnets 10B and 10C for the single crystal pulling apparatus, when the number of the pulling furnaces 1 is N (N is a natural number), N superconducting coils 11 are sufficient, so that The number of superconducting coils 11 can be reduced. Furthermore, by reducing the number of superconducting coils 11, it is possible to reduce the number of strong mechanical supports required as a countermeasure against the generated attractive force.

  It should be noted that the present invention is not limited to the above-described embodiment as it is, and can be implemented in various forms other than the above-described examples in the implementation stage, and various modifications can be made without departing from the spirit of the invention. Can be omitted, added, replaced, or changed. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Pulling furnace, 2 ... Heater, 3 ... Crucible (crucible), 4 ... Semiconductor material, 10 (10A, 10B, 10C, 10D) ... Superconducting electromagnet for single crystal pulling device, 11 ... Superconducting coil, 12 ... Refrigerant container , 13 (13a to 13e) ... cryostat, 14 ... communication tube, 18 ... magnetic body, 19 ... power supply equipment, 20 ... cooling equipment, 23 ... iron core for magnetic field correction.

Claims (5)

Arranging a plurality of cooling containers containing superconducting coils cooled by the refrigerant,
The cooling container is communicated by a communication pipe,
The superconducting device, wherein the communication pipe is configured to be able to supply a coolant supplied from a cooling facility to each of the cooling containers. 2. The superconducting device according to claim 1, wherein among the plurality of cooling containers arranged, a magnetic material is arranged on an end side of the cooling container located at both ends. 3. The superconducting device according to claim 2, wherein the cooling containers are arranged in a racetrack shape. The superconducting device according to claim 1, wherein the cooling container is arranged in an annular shape. 5. The superconducting device according to claim 4, wherein a magnetic field correcting iron core is inserted in the center of the superconducting coil in the cooling vessel.

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