Superconducting magnet and single crystal furnace equipment

Abstract

The invention relates to the technical field of single crystal growth, in particular to a superconducting magnet and single crystal furnace equipment, the superconducting magnet comprises a vacuum Dewar, a cold shield and a superconducting coil, a closed first annular cavity is formed in the vacuum Dewar, and a vacuum environment can be formed in the first annular cavity; the cold shield is arranged in the first annular cavity, a second annular cavity is formed in the cold shield, and a low-temperature environment can be formed in the second annular cavity; the two superconducting coils are respectively arranged at the upper part and the lower part of the second annular cavity and are used for forming a hook-shaped magnetic field; when the radial distance L between the superconducting magnet and the middle plane of the superconducting magnet is larger than 400 mm, the magnetic field intensity Br is larger than 1000 GS. By optimizing the structural design and magnetic field distribution of the superconducting magnet, the superconducting magnet has the specific magnetic field intensity at the specific radial distance, and the appropriate superconducting magnet can be matched or the superconducting magnet can be adaptively regulated and controlled according to the size of a single crystal furnace (or a crucible) and / or the growth efficiency requirement and the crystal pulling quality requirement of magnetic control straight pulling single crystals.

Description

Technical Field

[0001] This application relates to the field of single crystal growth technology, and in particular to a superconducting magnet and a single crystal furnace device. Background Technology

[0002] Magnetron Czochralski (MCS) single crystal growth furnaces play a crucial role in the field of semiconductor material preparation. With the continuous development of semiconductor technology, the requirements for the quality and performance of MCS single crystals are constantly increasing. In the MCS single crystal growth process, the superconducting magnet plays a key role, influencing not only the convection state of the melt but also directly determining the growth rate and crystal quality of the single crystal. Therefore, optimizing the superconducting magnet structure design and magnetic field distribution to improve the growth efficiency and crystal quality of MCS single crystals has become one of the important research focuses. Summary of the Invention

[0003] This application provides a superconducting magnet and a single crystal furnace device to improve the growth efficiency and crystal quality of magnetron Czochralski single crystals.

[0004] On one hand, this application provides a superconducting magnet, comprising: A vacuum Dewar has a closed first annular cavity inside, which can create a vacuum environment. The cold screen is set inside the first annular cavity, which has a second annular cavity inside, and a low-temperature environment can be formed in the second annular cavity. Two superconducting coils are provided, one in the upper part and one in the lower part of the second annular cavity, respectively, to form a hook-shaped magnetic field; When the magnetic field strength Br is located on the midplane of the superconducting magnet and the radial distance L from the central axis of the superconducting magnet is greater than 400 mm, the magnetic field strength Br is greater than 1000 GS.

[0005] In one possible design, when the radial distance L between the magnetic field located on the midplane of the superconducting magnet and the central axis of the superconducting magnet satisfies 400mm < L < 1000mm, the magnetic field strength Br satisfies 1000GS < Br < 10000GS.

[0006] In one possible design, when the radial distance L between the superconducting magnet and the central axis of the superconducting magnet is 400mm < L < 600mm, the magnetic field strength Br satisfies 1000GS < Br < 3000GS.

[0007] In one possible design, when the radial distance L between the superconducting magnet and the central axis of the superconducting magnet is 410mm < L < 500mm, the magnetic field strength Br satisfies 1200GS < Br < 1800GS. When the radial distance L between the superconducting magnet and the central axis of the superconducting magnet is 500mm < L < 560mm, the magnetic field strength Br satisfies 1800GS < Br < 2500GS.

[0008] In one possible design, a magnetic shield is also included, which covers the outer wall, upper end face, and lower end face of the vacuum Dewar. When the radial distance L1 from the outer wall of the magnetic shield is greater than 1300 mm, the magnetic field strength Br1 is less than 50 GS. When the axial distance L2 from the upper / lower end face of the magnetic shield is greater than 1400 mm, the magnetic field strength Br2 is less than 150 GS.

[0009] In one possible design, the operating current I of the superconducting coil satisfies 150A < I < 500A.

[0010] In one possible design, the operating current I of the superconducting coil satisfies 250A < I < 420A.

[0011] In one possible design, the operating current I of the superconducting coil satisfies 260A < I < 320A.

[0012] In one possible design, the number of turns n of the superconducting coil satisfies 1200N < n < 1800N.

[0013] In one possible design, the inner diameter R of the superconducting coil and the distance L3 between the two superconducting coils satisfy 2.4 < R / L3 < 3.0.

[0014] On the other hand, this application also provides a single crystal furnace apparatus, comprising: A single crystal furnace, containing a crucible for holding molten silicon; The superconducting magnets described above are coaxially fitted around the periphery of the single crystal furnace to form a hook-shaped magnetic field inside the crucible. The magnetic field strength Br3 at the intersection of the midplane of the superconducting magnet and the crucible wall satisfies 1000GS < Br3 < 3000GS.

[0015] In one possible design, the magnetic field strength Br3 at the intersection of the midplane of the superconducting magnet and the crucible wall satisfies 1200GS < Br3 < 2500GS.

[0016] The beneficial effects of this application are as follows: By optimizing the structural design and magnetic field distribution of superconducting magnets, they can have specific magnetic field strengths at specific radial distances. This allows for the matching of suitable superconducting magnets or adaptive control of superconducting magnets based on the size of the single crystal furnace (or crucible) and / or the growth efficiency and crystal pulling quality requirements of magnetron Czochralski single crystals.

[0017] By reasonably controlling the ratio range between the inner diameter of the superconducting coil and the distance between the two superconducting coils, the size, volume, weight, stability, and reliability of the superconducting magnet can be reasonably controlled while ensuring the required magnetic field strength.

[0018] The single crystal furnace equipment provided in this application incorporates the superconducting magnet described in this application, and therefore also incorporates all the aforementioned advantages of the superconducting magnet. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 A schematic diagram of the structure of the superconducting magnet provided in the embodiments of this application. Figure 1 ; Figure 2 A schematic diagram of the structure of the superconducting magnet provided in the embodiments of this application. Figure 2 .

[0021] Figure label: 1. Vacuum Dewar; 2. Cold shield; 3. Upper superconducting coil; 4. Lower superconducting coil; 5. Magnetic shield; 6. Coil frame; 7. Crucible; S - mid-plane; m - central axis. Detailed Implementation

[0022] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] The following is combined with Figures 1-2 This application describes the superconducting magnet and single crystal furnace equipment provided in the embodiments of this application.

[0024] Reference Figure 1As shown, the superconducting magnet provided in this embodiment includes a vacuum Dewar 1, a magnetic shield 5, a cold shield 2, a superconducting coil, and a refrigerator. The vacuum Dewar 1 has a closed first annular cavity inside, which creates a vacuum environment to isolate external heat and provide a stable low-temperature environment for the superconducting coil, ensuring its operation below the critical temperature and thus generating a stable magnetic field. The magnetic shield 5 is disposed on the outer wall, upper surface, and lower surface of the vacuum Dewar 1 to shield the leakage magnetic field generated by the superconducting magnet, reducing electromagnetic interference to surrounding equipment and protecting operators from the strong magnetic field. The cold shield 2 is located inside the first annular cavity of the vacuum Dewar 1, and a second annular cavity is formed inside the cold shield 2. This creates a low-temperature environment inside the cold shield 2, which can shield external heat radiation and further reduce the temperature of the environment surrounding the superconducting coil, thereby improving the operating efficiency and stability of the superconducting coil. The superconducting coil is located inside the cold shield 2. By precisely designing the number of turns, inner diameter, and spacing of the superconducting coil, the superconducting coil can generate a hook-shaped magnetic field that meets the requirements, thereby optimizing the growth process of magnetron Czochralski single crystal, improving growth efficiency and crystal pulling quality. The refrigerator is located outside the vacuum Dewar 1, which can provide continuous low-temperature cooling for the superconducting coil, thereby ensuring that the superconducting magnet operates in a stable low-temperature environment.

[0025] More specifically, the vacuum dewar 1 includes an upper end plate, a lower end plate, an outer cylinder, and an inner cylinder. The upper and lower end plates are welded to the upper and lower ends of the outer and inner cylinders, respectively, to form a closed, hollow, annular cylindrical structure. The vacuum dewar 1 has a through-hole in its center, or in other words, a through-hole is provided inside the inner cylinder, which is used to accommodate the single crystal furnace. The vacuum dewar 1 can be made of non-magnetic materials such as stainless steel.

[0026] More specifically, magnetic shielding bodies 5 are provided on the outer wall of the outer cylinder of the vacuum Dewar 1, the upper surface of the upper end plate, and the lower surface of the lower end plate. The magnetic shielding bodies 5 are made of magnetic materials so that the strong magnetic field generated by the superconducting magnet is confined to a certain area outside the magnetic shielding bodies 5.

[0027] In this embodiment, when the radial distance L1 from the outer wall of the magnetic shield 5 is greater than 1300 mm, the magnetic field strength Br1 is less than 50 GS. When the axial distance L2 from the upper or lower end face of the magnetic shield 5 is greater than 1400 mm, the magnetic field strength Br2 is less than 150 GS. That is, when the radial distance from the outer wall of the magnetic shield 5 exceeds 1300 mm and the axial distance from the upper or lower end face of the magnetic shield 5 exceeds 1400 mm, the magnetic field strength generated by the superconducting magnet is greatly reduced and reduced to within the safe threshold range.

[0028] In some embodiments, the upper end plate, lower end plate, and outer cylinder of the vacuum Dewar 1 can be made of magnetic materials to form a magnetic shield 5, while the inner cylinder is still made of non-magnetic materials, in order to simplify the structure of the superconducting magnet and reduce the weight of the superconducting magnet.

[0029] More specifically, the cold screen 2 includes an upper cover plate, a lower cover plate, an outer cylinder, and an inner cylinder. The upper and lower ends of the outer cylinder and the inner cylinder are respectively welded with upper and lower cover plates to form a hollow annular cylindrical structure. The cold screen 2 is housed inside the vacuum Dewar 1, that is, the outer cylinder of the cold screen 2 is located close to the outer cylinder of the vacuum Dewar 1, the inner cylinder of the cold screen 2 is located close to the inner cylinder of the vacuum Dewar 1, the upper cover plate of the cold screen 2 is located close to the upper end plate of the vacuum Dewar 1, and the lower cover plate of the cold screen 2 is located close to the lower end plate of the vacuum Dewar 1. In other words, the superconducting magnet is a double-layer hollow annular cylindrical structure.

[0030] More specifically, the superconducting coil includes an upper superconducting coil 3 and a lower superconducting coil 4, which are respectively located in the upper and lower parts of the cold screen 2, and the mid-planes of the upper superconducting coil 3 and the lower superconducting coil 4 are aligned with the mid-plane of the superconducting magnet. Furthermore, a coil frame 6 is provided within the cold screen 2, and the upper superconducting coil 3 and the lower superconducting coil 4 are wound around the upper and lower parts of the coil frame 6, respectively, and are connected in series.

[0031] In this embodiment, the superconducting coil can be spirally wound using high-temperature superconducting tape, and the number of turns of the upper superconducting coil 3 and the number of turns of the lower superconducting coil 4 can be the same or different.

[0032] More specifically, the refrigeration unit includes a primary cold head and a secondary cold head. The primary cold head can be connected to the cold screen 2 for heat conduction to reduce the temperature of the cold screen 2 to between 50-90K. The secondary cold head can be connected to the superconducting coil for heat conduction to reduce the temperature of the superconducting coil to below 20K, so as to ensure that the superconducting coil operates below the critical temperature.

[0033] In the embodiments of this application, the installation location, number of installations, and specific cooling connection method of the refrigerator can be adaptively adjusted and improved based on the existing technology according to the layout of the superconducting magnet and the single crystal furnace, the cooling requirements of the superconducting magnet, and the internal structure of the superconducting magnet, and no restrictions are imposed here.

[0034] In addition, the superconducting magnet also includes current leads connected to the superconducting coil. These current leads are connected to the excitation power supply to provide the required operating current to the superconducting coil according to the magnetic field strength requirements.

[0035] Furthermore, the superconducting magnet also includes tie rods that fix the superconducting coil within the cold shield 2 and the vacuum dewar 1 to ensure the stability of the superconducting coil's position within the superconducting magnet and prevent displacement or vibration during operation, thereby ensuring that the superconducting coil can stably generate the required magnetic field. Of course, the number, material, and shape of the tie rods can be adaptively adjusted and improved according to the overall structure of the superconducting magnet, the weight of the superconducting coil, and the operating environment of the superconducting magnet, and are not limited here.

[0036] In this embodiment, when the radial distance L from the midplane of the superconducting magnet to its central axis is greater than 400 mm, the magnetic field strength Br is greater than 1000 GS. When the midplane of the superconducting magnet coincides with the midplane of the two superconducting coils, the magnetic field strength Br is greater than 1000 GS when the radial distance L from the midplane of the two superconducting coils to its central axis is greater than 400 mm.

[0037] Furthermore, when a single-crystal furnace is installed in the through-hole of the superconducting magnet (i.e., vacuum Dewar 1), the magnetic field strength Br > 1000GS at the radial distance L > 400mm from the mid-plane of the superconducting magnet (or the central axis of the single-crystal furnace). The radial distance can be set to the location of the crucible 7 wall in the single crystal furnace, and the magnetic field strength can be set to the maximum magnetic field strength at the location of the crucible 7 wall in the single crystal furnace, that is, the magnetic field strength Br at the intersection of the mid-plane of the superconducting magnet and the crucible 7 wall is greater than 1000GS. For example, the magnetic field strength Br at the intersection of the mid-plane of the superconducting magnet and the crucible 7 wall can be 1100GS, 1200GS, 1300GS, 1400GS, 1500GS, 1600GS, 1700GS, 1800GS, 1900GS, 2000GS, 2100GS, 2200GS, 2300GS, 2400GS, 2500GS, 2600GS, 2700GS, 2800GS, 2900GS, 3000GS, 3100GS, 3200GS, etc.

[0038] More preferably, when the radial distance L between the mid-plane of the superconducting magnet and its central axis satisfies 400mm < L < 1000mm, the magnetic field strength Br satisfies: 1000GS < Br < 10000GS. When a single crystal furnace is installed in the through-hole of the superconducting magnet, when the radial distance between the mid-plane of the superconducting magnet and its central axis satisfies 400mm < L < 1000mm, the magnetic field strength Br satisfies: 1000GS < Br < 10000GS. That is, the magnetic field strength at the intersection of the mid-plane of the superconducting magnet and the wall of the crucible 7 satisfies: 1000GS < Br < 10000GS. For example, the magnetic field strength Br at the intersection of the mid-plane of the superconducting magnet and the wall of the crucible 7 is 1100GS, 1200GS, 1300GS, or 1400GS. S, 1500GS, 1600GS, 1700GS, 1800GS, 1900GS, 2000GS, 2100GS, 2200GS, 2300GS, 2400GS, 2500GS, 2600GS, 2700GS, 2800GS, 2900GS, 3000GS, 3100GS, 3200GS, etc., wherein the radial distance from the location of the crucible 7 wall to the central axis of the crucible 7 satisfies 400mm < L < 1000mm, that is, the size of the crucible 7 is approximately 32-78 inches.

[0039] More preferably, when the radial distance L between the mid-plane of the superconducting magnet and its central axis satisfies 400mm < L < 600mm, the magnetic field strength Br inside the superconducting magnet satisfies: 1000GS < Br < 3000GS. When a single crystal furnace is installed in the through-hole of the superconducting magnet, when the radial distance between the mid-plane of the superconducting magnet and its central axis satisfies 400mm < L < 600mm, the magnetic field strength Br satisfies: 1000GS < Br < 3000GS. That is, the magnetic field strength at the intersection of the mid-plane of the superconducting magnet and the wall of the crucible 7 satisfies: 1000GS < Br < 3000GS. For example, the magnetic field strength Br at the intersection of the mid-plane of the superconducting magnet and the wall of the crucible 7 is 1100GS, 1200GS, or 130GS. 0GS, 1400GS, 1500GS, 1600GS, 1700GS, 1800GS, 1900GS, 2000GS, 2100GS, 2200GS, 2300GS, 2400GS, 2500GS, 2600GS, 2700GS, 2800GS, 2900GS, etc., wherein the radial distance from the location of the crucible 7 wall to the central axis of the crucible 7 satisfies 400mm < L < 600mm, that is, the size of the crucible 7 is approximately 32-47 inches.

[0040] More preferably, when the radial distance L between the superconducting magnet and its central axis is 410mm < L < 500mm at the mid-plane of the superconducting magnet, the magnetic field strength Br inside the superconducting magnet satisfies 1200GS < Br < 1800GS. When a single crystal furnace is installed in the through-hole of a superconducting magnet, the magnetic field strength Br at the mid-plane of the superconducting magnet and the radial distance from the central axis of crucible 7 satisfies 410mm < L < 500mm, which satisfies 1200GS < Br < 1800GS. That is, the magnetic field strength at the mid-plane of the superconducting magnet and the intersection with the wall of crucible 7 satisfies 1000GS < Br < 1800GS. For example, the magnetic field strength Br at the intersection of the mid-plane of the superconducting magnet and the wall of crucible 7 is 1300GS, 1400GS, 1500GS, 1600GS, 1700GS, etc., where the radial distance from the position of the wall of crucible 7 to the central axis of crucible 7 satisfies 410mm < L < 500mm, that is, the size of crucible 7 is approximately 33-39 inches. For example, if the size of crucible 7 is 36 inches (the radial distance from the position of the wall of crucible 7 to the central axis of crucible 7 is approximately 450mm), the size of the single crystal rod that can be prepared is 12-14 inches.

[0041] When the radial distance L between the mid-plane of the superconducting magnet and its central axis satisfies 500mm < L < 560mm, the magnetic field strength Br inside the superconducting magnet satisfies 1800GS < Br < 2500GS. When a single-crystal furnace is installed in the through-hole of the superconducting magnet, when the radial distance between the mid-plane of the superconducting magnet and its central axis satisfies 500mm < L < 560mm, the magnetic field strength Br satisfies 1800GS < Br < 2500GS. That is, the magnetic field strength at the intersection of the mid-plane of the superconducting magnet and the wall of the crucible 7 satisfies 1800GS < Br < 2500GS. For example, if the magnetic field strength Br at the intersection of the mid-plane of the superconducting magnet and the wall of the crucible 7 is 1900G... S, 1950GS, 2000GS, 2100GS, 2200GS, 2300GS, 2400GS, etc., wherein the radial distance from the position of the crucible 7 wall to the central axis of the crucible 7 satisfies 500mm < L < 560mm, that is, the size of the crucible 7 is approximately 40-44 inches. For example, if the size of the crucible 7 is 42 inches (the radial distance from the position of the crucible 7 wall to the central axis of the crucible 7 is approximately 530mm), etc., the size of the single crystal rod that can be prepared is 14-16 inches.

[0042] In the embodiments of this application, the operating current I of the superconducting coil satisfies 150A < I < 500A. More preferably, the operating current I of the superconducting coil satisfies 250A < I < 420A. For example, the operating current I of the superconducting coil is 260A, 270A, 280A, 290A, 300A, 310A, 320A, 330A, 340A, 350A, 360A, 370A, 380A, 390A, 400A, 410A, etc. Furthermore, the operating current I of the superconducting coil satisfies 260A < I < 320A. For example, the operating current I of the superconducting coil is 270A, 275A, 280A, 290A, 300A, 310A, etc.

[0043] In a specific embodiment, the operating currents of the two superconducting coils may be the same or different, and the specific magnitude of the operating currents of the two superconducting coils can be adjusted according to the requirements of magnetic field strength and magnetic field distribution; at the same time, the maximum operating current of the two superconducting coils is related to the critical current of the superconducting coils themselves and the operating temperature required by the superconducting tape.

[0044] In this embodiment, the number of turns n of the superconducting coil satisfies 1200N < n < 1800N. For example, the number of turns n of the superconducting coil can be 1300N, 1400N, 1500N, 1600N, 1700N, etc. In a specific embodiment, the number of turns n of the upper superconducting coil 3 can be any one of 1300N, 1400N, 1500N, 1600N, 1700N, etc., and the number of turns n of the lower superconducting coil 4 can be any one of 1300N, 1400N, 1500N, 1600N, 1700N, etc. That is, the number of turns of the upper superconducting coil 3 and the lower superconducting coil 4 can be the same or different, specifically determined according to the requirements of magnetic field strength and magnetic field distribution. For example, the more turns the superconducting coil has, the greater the magnetic field strength generated under the same operating current; however, increasing the number of turns also leads to increased manufacturing costs and cooling... However, the difficulty increases. Therefore, under the premise of meeting the magnetic field strength requirements, the number of turns n of the superconducting coil should be reasonably selected to satisfy 1200N < n < 1800N. At the same time, the radial and axial number of turns of the upper superconducting coil 3 and the lower superconducting coil 4 can be determined according to the requirements of magnetic field strength, magnetic field distribution, magnet structure, single crystal furnace structure, etc. For example, the radial number of turns can be any one of 50, 55, 60, 65, 70, 75, 80, 85, 90, etc., and the axial number of turns can be any one of 15, 20, 25, 30, etc. There are no restrictions here. Only the total number of turns of the upper superconducting coil 3 and the lower superconducting coil 4 is restricted and explained.

[0045] In this embodiment, the inner diameter R of the superconducting coil and the distance L3 between the two superconducting coils satisfy 2.4 < R / L3 < 3.0. For example, the ratio of the inner diameter R of the superconducting coil to the distance L3 between the two superconducting coils can be 2.5, 2.6, 2.7, 2.8, 2.9, etc., where the inner diameter of the superconducting coil is set as its center diameter, and the distance between the two superconducting coils is set as the axial distance between their centers. In a specific embodiment, the ratio of the inner diameter R of the superconducting coil to the distance L3 between the two superconducting coils is related to the required magnetic field strength and distribution. When the ratio of the inner diameter R of the superconducting coil to the distance L3 between the two superconducting coils is within the above range, the distribution of the magnetic field within the superconducting magnet can be optimized, so that when the radial distance from the mid-plane of the superconducting magnet to its central axis meets a specific range, the magnetic field strength and distribution can meet the conditions required for single crystal growth.

[0046] This application optimizes the structural design and magnetic field distribution of superconducting magnets to enable them to have specific magnetic field strengths at specific radial distances. It can match suitable superconducting magnets or adaptively control superconducting magnets according to the size of the single crystal furnace (or crucible 7) and / or the growth efficiency requirements and crystal pulling quality requirements (such as the oxygen content, resistivity, impurity concentration, etc. of the crystal rod).

[0047] Secondly, this application also provides a single crystal furnace device, including a single crystal furnace and a superconducting magnet. The single crystal furnace is used to melt silicon raw materials and pull single crystal rods. The single crystal furnace includes a crucible 7 for containing the molten silicon material, a heater for heating and melting the silicon material and continuously heating the molten silicon, a crucible drive assembly for driving the crucible 7 to rotate and move, and a seed crystal pulling assembly for pulling the single crystal rods. The superconducting magnet is coaxially sleeved around the single crystal furnace to provide the required magnetic field environment for the single crystal furnace, such as a hook-shaped magnetic field environment.

[0048] In this embodiment, the main furnace chamber of the single crystal furnace is inserted through the through hole of the superconducting magnet, and the crucible 7 in the single crystal furnace is located near the mid-plane of the superconducting magnet, so as to ensure that the location of the crucible 7 wall can obtain a suitable magnetic field strength and magnetic field distribution during the single crystal rod pulling process, thereby improving the growth quality and growth efficiency of the single crystal rod.

[0049] In some embodiments, the magnetic field strength Br3 at the intersection of the mid-plane of the superconducting magnet and the crucible wall satisfies 1000GS < Br3 < 3000GS. For example, when the crucible size is 32-47 inches, the magnetic field strength Br3 at the intersection of the mid-plane of the superconducting magnet and the crucible wall is 1100GS, 1200GS, 1300GS, 1400GS, 1500GS, 1600GS, 1700GS, 1800GS, 1900GS, 2000GS, 2100GS, 2200GS, 2300GS, 2400GS, 2500GS, 2600GS, 2700GS, 2800GS, 2900GS, etc. More preferably, the magnetic field strength Br3 at the intersection of the mid-plane of the superconducting magnet and the crucible wall satisfies 1200GS < Br3 < 2500GS. When the crucible size is 33-44 inches, the magnetic field strength Br3 at the intersection of the mid-plane of the superconducting magnet and the wall of the crucible is 1300GS, 1400GS, 1500GS, 1600GS, 1700GS, 1800GS, 1950GS, 1900GS, 2000GS, 2100GS, 2200GS, 2300GS, 2400GS, etc., and the size of the single crystal rod that can be prepared is 12-16 inches.

[0050] Table 1 shows the correlation between different design parameters and the magnetic field strength at the intersection of the plane and the crucible wall in the superconducting magnet.

[0051] Example 1: When it is necessary to prepare a 16-inch single crystal rod, a 42-inch crucible 7 (the radial distance from the wall of crucible 7 to the central axis at the plane of the superconducting magnet is about 530 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1600 turns, the number of turns of the lower superconducting coil 4 is set to 1600 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.5, and the operating current of the superconducting coil is 300A. This can generate a magnetic field strength of 2000GS at the intersection of the plane of the superconducting magnet and the crucible wall. This magnetic field strength can meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0052] Example 2: When it is necessary to prepare a 16-inch single crystal rod, a 42-inch crucible 7 (the radial distance from the wall of crucible 7 to the central axis at the plane of the superconducting magnet is about 530 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1600 turns, the number of turns of the lower superconducting coil 4 is set to 1600 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.5, and the operating current of the superconducting coil is 275A. This can generate a magnetic field strength of 1900GS at the intersection of the plane of the superconducting magnet and the crucible wall. This magnetic field strength can meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0053] Example 3: When it is necessary to prepare a 16-inch single crystal rod, a 42-inch crucible 7 (the radial distance from the wall of crucible 7 to the central axis at the plane of the superconducting magnet is about 530 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1400 turns, the number of turns of the lower superconducting coil 4 is set to 1600 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.5, and the operating current of the superconducting coil is 300A. This can generate a magnetic field strength of 1950GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength can meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0054] Example 4: When it is necessary to prepare a 16-inch single crystal rod, a 42-inch crucible 7 (the radial distance from the wall of crucible 7 to the central axis at the plane of the superconducting magnet is about 530 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1500 turns, the number of turns of the lower superconducting coil 4 is set to 1500 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.5, and the operating current of the superconducting coil is 300A. This can generate a magnetic field strength of 1900GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength can meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0055] Example 5: When it is necessary to prepare a 16-inch single crystal rod, a 42-inch crucible 7 (the radial distance from the wall of crucible 7 to the central axis at the plane of the superconducting magnet is about 530 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1600 turns, the number of turns of the lower superconducting coil 4 is set to 1600 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.7, and the operating current of the superconducting coil is 300A. This can generate a magnetic field strength of 1900GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength can meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0056] Comparative Example 1: When it is necessary to prepare a 16-inch single crystal rod, a 42-inch crucible 7 (the radial distance from the wall of crucible 7 to the central axis at the plane of the superconducting magnet is about 530 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1600 turns, the number of turns of the lower superconducting coil 4 is set to 1600 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.5, and the operating current of the superconducting coil is 200A. At this time, since the operating current is less than the design requirement, the superconducting magnet can only generate a magnetic field strength of 1400GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength is less than the design requirement and cannot meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0057] Comparative Example 2: When it is necessary to prepare a 16-inch single crystal rod, a 42-inch crucible 7 (the radial distance from the wall of crucible 7 at the plane of the superconducting magnet to the central axis is about 530 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1500 turns, the number of turns of the lower superconducting coil 4 is set to 1500 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.5, and the operating current of the superconducting coil is 200A. At this time, since the operating current is less than the design requirement, the superconducting magnet can only generate a magnetic field strength of 1350GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength is less than the design requirement and cannot meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0058] Comparative Example 3: When it is necessary to prepare a 16-inch single crystal rod, a 42-inch crucible 7 (the radial distance from the wall of crucible 7 to the central axis at the plane of the superconducting magnet is about 530 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1600 turns, the number of turns of the lower superconducting coil 4 is set to 1600 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 3.5, and the operating current of the superconducting coil is 300A. At this time, since the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is greater than the design requirement, the superconducting magnet can only generate a magnetic field strength of 1700GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength is less than the design requirement and cannot meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0059] In summary, in Examples 1-5, since the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils, the number of turns of the superconducting coil, and the operating current of the superconducting coil all meet the design requirements, the magnetic field strength generated by the superconducting magnet at the intersection of the plane within the superconducting magnet and the crucible wall can meet the requirements for the crystal pulling quality and efficiency of the single crystal rod. However, in Comparative Examples 1-3, since the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils, or the operating current of the superconducting coil, or the number of turns of the superconducting coil does not meet the design requirements, the magnetic field strength generated by the superconducting magnet at the intersection of the plane within the superconducting magnet and the crucible wall cannot meet the requirements for the crystal pulling quality and efficiency of the single crystal rod.

[0060] Example 6: When it is necessary to prepare a 12-inch single crystal rod, a 36-inch crucible 7 (the radial distance from the wall of crucible 7 at the plane of the superconducting magnet to the central axis is about 450 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1600 turns, the number of turns of the lower superconducting coil 4 is set to 1600 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.5, and the operating current of the superconducting coil is 300A. This can generate a magnetic field strength of 1500GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength can meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0061] Example 7: When it is necessary to prepare a 12-inch single crystal rod, a 36-inch crucible 7 (the radial distance from the wall of crucible 7 to the central axis at the plane of the superconducting magnet is about 450 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1600 turns, the number of turns of the lower superconducting coil 4 is set to 1600 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.5, and the operating current of the superconducting coil is 275A. This can generate a magnetic field strength of 1400GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength can meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0062] Example 8: When it is necessary to prepare a 12-inch single crystal rod, a 36-inch crucible 7 (the radial distance from the wall of crucible 7 to the central axis at the plane of the superconducting magnet is about 450 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1400 turns, the number of turns of the lower superconducting coil 4 is set to 1600 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.5, and the operating current of the superconducting coil is 300A. This can generate a magnetic field strength of 1400GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength can meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0063] Example 9: When it is necessary to prepare a 12-inch single crystal rod, a 36-inch crucible 7 (the radial distance from the wall of crucible 7 at the plane of the superconducting magnet to the central axis is about 450 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1500 turns, the number of turns of the lower superconducting coil 4 is set to 1500 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.5, and the operating current of the superconducting coil is 300A. This can generate a magnetic field strength of 1400GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength can meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0064] Example 10: When it is necessary to prepare a 12-inch single crystal rod, a 36-inch crucible 7 (the radial distance from the wall of crucible 7 to the central axis at the plane of the superconducting magnet is about 450 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1600 turns, the number of turns of the lower superconducting coil 4 is set to 1600 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.7, and the operating current of the superconducting coil is 300A. This can generate a magnetic field strength of 1300GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength can meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0065] Comparative Example 4: When it is necessary to prepare a 12-inch single crystal rod, a 36-inch crucible 7 (the radial distance from the wall of crucible 7 at the plane of the superconducting magnet to the central axis is about 450 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1600 turns, the number of turns of the lower superconducting coil 4 is set to 1600 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.5, and the operating current of the superconducting coil is 200A. At this time, since the operating current is less than the design requirement, the superconducting magnet can only generate a magnetic field strength of 1100GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength is less than the design requirement and cannot meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0066] Comparative Example 5: When it is necessary to prepare a 12-inch single crystal rod, a 36-inch crucible 7 (the radial distance from the wall of crucible 7 to the central axis at the plane of the superconducting magnet is about 450 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1500 turns, the number of turns of the lower superconducting coil 4 is set to 1500 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 2.5, and the operating current of the superconducting coil is 200A. At this time, since the operating current is less than the design requirement, the superconducting magnet can only generate a magnetic field strength of 1000GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength is less than the design requirement and cannot meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0067] Comparative Example 6: When it is necessary to prepare a 12-inch single crystal rod, a 36-inch crucible 7 (the radial distance from the wall of crucible 7 at the plane of the superconducting magnet to the central axis is about 450 mm) can be used. At the same time, the number of turns of the upper superconducting coil 3 is set to 1600 turns, the number of turns of the lower superconducting coil 4 is set to 1600 turns, the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is 3.5, and the operating current of the superconducting coil is 300A. At this time, since the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils is greater than the design requirement, the superconducting magnet can only generate a magnetic field strength of 1100GS at the intersection of the plane of the superconducting magnet and the wall of crucible 7. This magnetic field strength is less than the design requirement and cannot meet the requirements of crystal pulling quality and crystal pulling efficiency of the single crystal rod.

[0068] In summary, in Examples 6-10, since the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils, the number of turns of the superconducting coil, and the operating current of the superconducting coil all meet the design requirements, the magnetic field strength generated by the superconducting magnet at the intersection of the plane within the superconducting magnet and the crucible wall is sufficient to meet the requirements for the crystal pulling quality and efficiency of the single crystal rod. However, in Comparative Examples 4-6, since the ratio of the inner diameter of the superconducting coil to the distance between the two superconducting coils, or the operating current of the superconducting coil, or the number of turns of the superconducting coil does not meet the design requirements, the magnetic field strength generated by the superconducting magnet at the intersection of the plane within the superconducting magnet and the crucible wall is insufficient to meet the requirements for the crystal pulling quality and efficiency of the single crystal rod.

[0069] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0070] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0071] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0072] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0073] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A superconducting magnet, characterized in that, include: A vacuum Dewar has a closed first annular cavity inside, which can create a vacuum environment. The cold screen is set inside the first annular cavity, which has a second annular cavity inside, and a low-temperature environment can be formed in the second annular cavity. Two superconducting coils are provided, one in the upper part and one in the lower part of the second annular cavity, respectively, to form a hook-shaped magnetic field; When the magnetic field strength Br is located on the midplane of the superconducting magnet and the radial distance L from the central axis of the superconducting magnet is greater than 400 mm, the magnetic field strength Br is greater than 1000 GS.

2. The superconducting magnet according to claim 1, characterized in that, When the radial distance L between the superconducting magnet and the central axis of the superconducting magnet is 400mm < L < 1000mm, the magnetic field strength Br satisfies 1000GS < Br < 10000GS.

3. The superconducting magnet according to claim 2, characterized in that, When the radial distance L between the superconducting magnet and the central axis of the superconducting magnet is 400mm < L < 600mm, the magnetic field strength Br satisfies 1000GS < Br < 3000GS.

4. The superconducting magnet according to claim 3, characterized in that, When the radial distance L between the superconducting magnet and the central axis of the superconducting magnet is 410mm < L < 500mm, the magnetic field strength Br satisfies 1200GS < Br < 1800GS. When the radial distance L between the superconducting magnet and the central axis of the superconducting magnet is 500mm < L < 560mm, the magnetic field strength Br satisfies 1800GS < Br < 2500GS.

5. The superconducting magnet according to any one of claims 1-4, characterized in that, It also includes a magnetic shield, which covers the outer wall, upper end face and lower end face of the vacuum Dewar. When the radial distance L1 to the outer wall of the magnetic shield is greater than 1300 mm, the magnetic field strength Br1 is less than 50 GS. When the axial distance L2 to the upper / lower end face of the magnetic shield is greater than 1400 mm, the magnetic field strength Br2 is less than 150 GS.

6. The superconducting magnet according to any one of claims 1-4, characterized in that, The operating current I of the superconducting coil satisfies 150A < I < 500A.

7. The superconducting magnet according to claim 6, characterized in that, The operating current I of the superconducting coil satisfies 250A < I < 420A.

8. The superconducting magnet according to claim 7, characterized in that, The operating current I of the superconducting coil satisfies 260A < I < 320A.

9. The superconducting magnet according to claim 6, characterized in that, The number of turns n of the superconducting coil satisfies 1200N < n < 1800N.

10. The superconducting magnet according to claim 9, characterized in that, The inner diameter R of the superconducting coil and the distance L3 between the two superconducting coils satisfy 2.4 < R / L3 < 3.

0.

11. A single crystal furnace device, characterized in that, include: A single crystal furnace, containing a crucible for holding molten silicon; The superconducting magnet according to any one of claims 1-10 is coaxially sleeved around the periphery of a single crystal furnace for forming a hook-shaped magnetic field inside the crucible; The magnetic field strength Br3 at the intersection of the midplane of the superconducting magnet and the crucible wall satisfies 1000GS < Br3 < 3000GS.

12. A single crystal furnace apparatus according to claim 11, characterized in that, The magnetic field strength Br3 at the intersection of the midplane of the superconducting magnet and the crucible wall satisfies 1200GS < Br3 < 2500GS.

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