Single crystal silicon production apparatus, superconducting magnet, and method for adjusting magnetic field of superconducting magnet

Abstract

The application discloses a single crystal silicon production equipment, a superconducting magnet and a magnetic field adjusting method thereof. The superconducting magnet comprises a superconducting magnetic group and a power supply. The superconducting magnetic group comprises at least two superconducting magnetic groups and at least two coils. At least two first coils in the at least two superconducting magnetic groups are arranged in an axial direction of the first coil. The at least two first coils are located above a first plane. The second coil in the at least two superconducting magnetic groups is symmetrically arranged with the corresponding first coil relative to the first plane. The power supply corresponds to the superconducting magnetic group one by one. The first coil and the second coil in the superconducting magnetic group are connected in series on a power supply loop of the corresponding power supply. The superconducting magnet provided by the application has the advantages that the convection inhibition effect on the silicon melt is better, and the oxygen content of the single crystal rod formed by drawing is low.

Description

Technical Field

[0001] This invention relates to the field of superconducting magnet technology, specifically to a single-crystal silicon production equipment, a superconducting magnet, and a method for adjusting its magnetic field. Background Technology

[0002] Chips are the core components of smart electronic devices. The basic material for chips is monocrystalline silicon, which is mostly prepared using the Czochralski method. In the process of growing semiconductor monocrystalline silicon using the Czochralski method, a crucible in a monocrystalline furnace is filled with polycrystalline silicon. After being heated, the polycrystalline silicon becomes a silicon melt. The silicon melt tumbles up and down in the crucible, forming thermal convection. The thermal convection washes over the crucible wall, causing oxygen molecules in the crucible to precipitate and enter the silicon melt. This increases the oxygen content in the pulled monocrystalline silicon rod, seriously affecting the quality of the monocrystalline silicon.

[0003] In related technologies, such as Figure 1 As shown, a hook-shaped magnetic field is typically installed around the periphery of single-crystal silicon in a superconducting magnet used for Czochralski (CZ) single crystal pulling. This typically includes a pair of superconducting solenoid coils spaced vertically, with currents of the same magnitude but opposite directions flowing through them to generate a hook-shaped magnetic field inside the coils. The magnetic field component perpendicular to the crucible wall in this hook-shaped magnetic field effectively suppresses the flow (convection) of the molten silicon, preventing it from eroding the crucible wall and thus preventing oxygen molecules from entering the molten silicon. However, the magnetic field component perpendicular to the crucible wall generated by this superconducting magnet gradually weakens from top to bottom along the crucible wall, meaning it has the strongest convection suppression effect on the surface of the molten silicon and the weakest at the bottom. Therefore, the convection suppression effect on the molten silicon is not complete, resulting in a single crystal rod with excessively high oxygen content. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose a superconducting magnet that has the advantages of better convection suppression effect on silicon melt and low oxygen content in the pulled single crystal rod.

[0006] Embodiments of the present invention also propose a monocrystalline silicon production equipment.

[0007] The embodiments of the present invention further propose a method for adjusting the magnetic field of a superconducting magnet.

[0008] According to an embodiment of the present invention, a superconducting magnet includes a superconducting magnetic assembly and a power supply. The superconducting magnetic assembly has at least two components and includes a first coil and a second coil. At least two of the first coils in the at least two superconducting magnetic assemblies are arranged at intervals along the axial direction of the first coil, and both of the at least two first coils are located above the first plane. The second coils in the at least two superconducting magnetic assemblies are arranged symmetrically with respect to the first plane relative to the corresponding first coil. The power supply corresponds one-to-one with the superconducting magnetic assembly, and the first coil and the second coil in the superconducting magnetic assembly are connected in series in the power supply circuit of the corresponding power supply.

[0009] According to the superconducting magnet of the present invention, different output currents are supplied to the corresponding superconducting magnetic groups by different power supplies, so that the current of the first coil near the first plane is always less than the current of the first coil far from the first plane. This allows the hook-shaped magnetic field formed by at least two superconducting magnetic groups to form a larger magnetic field component perpendicular to the crucible wall at a position further away from the first plane, which can better suppress convection at the bottom of the silicon melt. As a result, the overall convection suppression effect of the silicon melt is better, thereby effectively preventing oxygen molecules from the crucible from entering the silicon melt. The resulting single crystal rod has a lower oxygen content and better quality.

[0010] In some embodiments, the number of both the superconducting magnetic array and the power source is two.

[0011] In some embodiments, the superconducting magnet further includes a first shaft for winding the first coil and a second shaft for winding the second coil, both the first shaft and the second shaft being cylindrical structures adapted to be fitted around the outer periphery of a single crystal furnace.

[0012] In some embodiments, there is one first shaft and one second shaft, at least two first coils are wound on the first shaft, at least two second coils are wound on the second shaft, a first partition is provided on the outer periphery of the first shaft, a second partition is provided on the outer periphery of the second shaft, the first partition is located between any two adjacent first coils, and the second partition is located between any two adjacent second coils.

[0013] In some embodiments, both the first partition and the second partition are insulating ring plates.

[0014] According to an embodiment of the present invention, a single crystal silicon production apparatus includes a single crystal furnace and a superconducting magnet as described in any of the above embodiments. The first coil and the second coil are both sleeved on the outer periphery of the single crystal furnace and arranged at intervals along the height direction of the single crystal furnace.

[0015] The technical advantages of the monocrystalline silicon production equipment according to the embodiments of the present invention are the same as those of the superconducting magnets in the above embodiments, and will not be repeated here.

[0016] In some embodiments, the single crystal furnace is equipped with a crucible for holding molten silicon, the surface of which is coplanar with the first plane.

[0017] In some embodiments, the crucible is movably connected to the single crystal furnace along the height direction of the single crystal furnace.

[0018] The magnetic field adjustment method of the superconducting magnet according to embodiments of the present invention, using a superconducting magnet as described in any of the above embodiments, includes the following steps:

[0019] The first and second coils in the superconducting magnetic assembly are connected in series in the power supply circuit of the corresponding power source, so that the current in the first and second coils is in opposite directions.

[0020] While ensuring that the total current of at least two first coils is I, the output current of each power supply is controlled so that in any two adjacent first coils, the current of the first coil near the first plane is always less than the current of the first coil far from the second plane.

[0021] By adjusting the output current of each power source, different current ratios can be obtained between any two adjacent first coils, thus forming hook-shaped magnetic fields of different shapes.

[0022] The magnetic field adjustment method of the superconducting magnet according to the embodiments of the present invention has the same technical advantages as the superconducting magnet in the above embodiments, and will not be repeated here.

[0023] In some embodiments, there are two superconducting magnetic groups and two power sources. Among the two first coils, the current of the first coil adjacent to the first plane is 0.5I-α, and the current of the first coil away from the second plane is 0.5I+α, where 0<α≤0.25I. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of existing monocrystalline silicon production equipment.

[0025] Figure 2 This is a schematic diagram of a monocrystalline silicon production equipment according to an embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the thermal convection direction inside the crucible and a diagram showing the magnitude and location distribution of the magnetic field inside the crucible in a single-crystal silicon production equipment according to an embodiment of the present invention.

[0027] Figure label:

[0028] 1. First coil; 2. Second coil; 3. First partition; 4. Second partition; 5. Crucible; 51. Silicon melt; 52. First plane; 53. Single crystal rod; 6. Single crystal furnace; 7. Hook-shaped magnetic field. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0030] The following is combined with Figures 1-3 A superconducting magnet according to an embodiment of the present invention is described.

[0031] According to an embodiment of the present invention, a superconducting magnet includes a superconducting magnetic assembly and a power supply. The superconducting magnetic assembly has at least two components and includes a first coil 1 and a second coil 2. At least two first coils 1 in the at least two superconducting magnetic assemblies are arranged at intervals along the axial direction of the first coil 1. The at least two first coils 1 are all located above a first plane 52. The second coils 2 in the at least two superconducting magnetic assemblies are symmetrically arranged with respect to the first plane 52 relative to the corresponding first coil 1. The power supply corresponds one-to-one with the superconducting magnetic assembly. The first coil 1 and the second coil 2 in the superconducting magnetic assembly are connected in series in the power supply circuit of the corresponding power supply.

[0032] According to the superconducting magnet of the present invention, different output currents are supplied to the corresponding superconducting magnetic groups by different power supplies, so that the current of the first coil 1 near the first plane 52 is always less than the current of the first coil 1 far from the first plane 52. As a result, the hook-shaped magnetic field 7 formed by at least two superconducting magnetic groups can form a larger magnetic field component perpendicular to the wall of the crucible 5 at a position further away from the first plane 52. That is, it can better suppress the convection at the bottom of the silicon melt 51. As a result, the overall convection suppression effect of the silicon melt 51 is better, thereby effectively preventing oxygen molecules from the crucible 5 from entering the silicon melt 51. The resulting single crystal rod 53 has a lower oxygen content and better quality.

[0033] It should be noted that the power supply is a DC constant current power supply. The multiple first coils 1 located above the first plane 52 are formed by equally dividing the upper coil of two coils in related technologies. That is, in this embodiment, the upper coil in related technologies is divided into multiple parts along the axial direction to form multiple first coils 1. In addition, when the superconducting magnet is working, the current in the first coil 1 and the corresponding second coil 2 is the same but in opposite directions. Figure 3 As shown, the arrows with dotted lines represent newly added magnetic field components, and the arrows with straight lines represent existing magnetic field components. The longer the straight line, the higher the magnetic field strength at the corresponding position. The multiple hollow arrows inside the silicon melt 51 represent the convection direction. At this time, the newly added magnetic field component can be located at the bottom of the silicon melt 51 to achieve convection suppression at the bottom of the silicon melt 51.

[0034] In some embodiments, the number of superconducting magnets and power sources are both two.

[0035] Thus, the hook-shaped magnetic field 7 formed by the superconducting magnet ensures the convection suppression effect on the silicon melt 51 in the crucible 5, while the superconducting magnet has a simple structure and is easy to install.

[0036] Specifically, in actual use, while ensuring that the current of the first coil 1 adjacent to the first plane 52 is less than the current of the first coil 1 far from the first plane 52, the output current of the two power supplies can be flexibly adjusted to adjust the current ratio of the two first coils 1, thereby obtaining a hook-shaped magnetic field 7 that has a better convection suppression effect on the silicon melt 51.

[0037] In some embodiments, the superconducting magnet further includes a first shaft for winding the first coil 1 and a second shaft for winding the second coil 2 (not shown in the figure), both the first shaft and the second shaft being cylindrical structures and adapted to be fitted around the outer periphery of the single crystal furnace 6.

[0038] The first axis ensures support for the first coil 1, and the second axis ensures support for the second coil 2. The connection between the first axis and the second axis and the single crystal furnace 6 ensures the relative fixation of the positions of the first coil 1 and the second coil 2 relative to the crucible 5 inside the single crystal furnace 6, thereby ensuring the convection suppression effect of the hook-shaped magnetic field 7 on the silicon melt 51.

[0039] In some embodiments, such as Figure 2 As shown, there is one first shaft and one second shaft. At least two first coils 1 are wound on the first shaft and at least two second coils 2 are wound on the second shaft. A first partition 3 is provided on the outer periphery of the first shaft and a second partition 4 is provided on the outer periphery of the second shaft. The first partition 3 is located between any two adjacent first coils 1 and the second partition 4 is located between any two adjacent second coils 2.

[0040] The first partition 3 separates the two first coils 1 located on the first axis, and the second partition 4 separates the two second coils 2 located on the second axis, thereby effectively preventing the two first coils 1 or the two second coils 2 from accidentally contacting and short-circuiting, which would affect the formation of the hook-shaped magnetic field 7.

[0041] In some embodiments, the first partition 3 and the second partition 4 are both insulating ring plates. Thus, the first partition 3 provides better separation and insulation for the two first coils 1 on the first shaft, and the second partition 4 provides better separation and insulation for the two second coils 2 on the second shaft.

[0042] Specifically, the inner circumferential surface of the first partition 3 is bonded to the outer circumferential surface of the first shaft, and the radial dimension of the first partition 3 is greater than or equal to the radial dimension of the first coil 1. The inner circumferential surface of the second partition 4 is bonded to the outer circumferential surface of the second shaft, and the radial dimension of the second partition 4 is greater than or equal to the radial dimension of the second coil 2.

[0043] According to an embodiment of the present invention, a single crystal silicon production equipment includes a single crystal furnace 6 and a superconducting magnet as described in any of the above embodiments. The first coil 1 and the second coil 2 are both sleeved on the outer periphery of the single crystal furnace 6 and arranged at intervals along the height direction of the single crystal furnace 6.

[0044] The technical advantages of the monocrystalline silicon production equipment according to the embodiments of the present invention are the same as those of the superconducting magnets in the above embodiments, and will not be repeated here.

[0045] In some embodiments, such as Figure 2 As shown, a crucible 5 for holding silicon melt 51 is installed inside the single crystal furnace 6, and the liquid surface of silicon melt 51 is coplanar with the first plane 52.

[0046] Therefore, the hook-shaped magnetic field 7 formed by the superconducting magnet has the largest magnetic field component perpendicular to the wall of the crucible 5 at the first plane 52, which has a better convection suppression effect on the silicon melt 51 and the quality of the formed single crystal rod 53 is higher.

[0047] In some embodiments, the crucible 5 is movably connected to the single crystal furnace 6 along the height direction of the single crystal furnace 6.

[0048] As the single crystal rod 53 is gradually pulled into shape, the liquid level of the silicon melt 51 will gradually decrease. At this time, the crucible 5 can gradually move upward relative to the single crystal furnace 6 to ensure that the liquid level of the silicon melt 51 is always coplanar with the first plane 52, thereby better ensuring the convection suppression effect of the superconducting magnet on the silicon melt 51.

[0049] The magnetic field adjustment method for a superconducting magnet according to embodiments of the present invention, using a superconducting magnet as described in any of the above embodiments, includes the following steps:

[0050] The first coil 1 and the second coil 2 in the superconducting magnetic assembly are connected in series in the power supply circuit of the corresponding power source, so that the current in the first coil 1 and the second coil 2 are in opposite directions.

[0051] While ensuring that the total current of at least two first coils 1 is I, the output current of each power supply is controlled so that in any two adjacent first coils 1, the current of the first coil 1 near the first plane 52 is always less than the current of the first coil 1 far from the second plane.

[0052] By adjusting the output current of each power source, different current ratios can be obtained for any two adjacent first coils 1, and hook-shaped magnetic fields 7 of different shapes can be formed.

[0053] The magnetic field adjustment method of the superconducting magnet according to the embodiments of the present invention has the same technical advantages as the superconducting magnet in the above embodiments, and will not be repeated here.

[0054] In some embodiments, there are two superconducting magnetic groups and two power sources. Among the two first coils 1, the current of the first coil 1 adjacent to the first plane 52 is 0.5I-α, and the current of the first coil 1 away from the second plane is 0.5I+α, where 0<α≤0.25I.

[0055] Compared to the hook-shaped magnetic field 7 in related technologies, the hook-shaped magnetic field 7 formed within the above range can always achieve a better convection suppression effect on the silicon melt 51, ensuring the quality of the pulled single crystal rod 53.

[0056] Specifically, in the related technology, the current of each of the two coils is I. The current of the first coil 1 adjacent to the first plane 52 can be 0.5I, 0.75I, and 0.9I, etc., and correspondingly, the current of the first coil 1 away from the first plane 52 can be 1.5I, 1.25I, and 1.1I, etc.

[0057] In the description of this invention, 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," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0058] 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 invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0059] In this invention, unless otherwise explicitly 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 them; 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 explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0060] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0061] In this invention, 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 the invention. 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.

[0062] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A superconducting magnet, characterized in that, include: A superconducting magnetic assembly, wherein there are at least two superconducting magnetic assemblies and each superconducting magnetic assembly includes a first coil and a second coil, wherein at least two of the first coils in the at least two superconducting magnetic assemblies are arranged at intervals along the axial direction of the first coil, and both of the at least two first coils are located above a first plane, and both of the second coils in the at least two superconducting magnetic assemblies are arranged symmetrically with respect to the first plane relative to the corresponding first coil. and The power supply corresponds one-to-one with the superconducting magnetic group. The first coil and the second coil in the superconducting magnetic group are connected in series in the power supply circuit of the corresponding power supply. On the basis of ensuring that the total current of at least two first coils is I, the output current of each power supply is controlled so that in any two adjacent first coils, the current of the first coil near the first plane is always less than the current of the first coil far from the first plane.

2. The superconducting magnet according to claim 1, characterized in that, The number of superconducting magnetic assemblies and the number of power sources are both two.

3. The superconducting magnet according to claim 1, characterized in that, The superconducting magnet also includes a first shaft for winding the first coil and a second shaft for winding the second coil. Both the first shaft and the second shaft are cylindrical structures and are adapted to be sleeved on the outer periphery of the single crystal furnace.

4. The superconducting magnet according to claim 3, characterized in that, There is one first shaft and one second shaft. At least two first coils are wound on the first shaft and at least two second coils are wound on the second shaft. A first partition is provided on the outer periphery of the first shaft and a second partition is provided on the outer periphery of the second shaft. The first partition is located between any two adjacent first coils and the second partition is located between any two adjacent second coils.

5. The superconducting magnet according to claim 4, characterized in that, Both the first partition and the second partition are insulating ring plates.

6. A monocrystalline silicon production equipment, characterized in that, It includes a single crystal furnace and a superconducting magnet as described in any one of claims 1-5, wherein the first coil and the second coil are both sleeved on the outer periphery of the single crystal furnace and arranged at intervals along the height direction of the single crystal furnace.

7. The monocrystalline silicon production equipment according to claim 6, characterized in that, The single crystal furnace is equipped with a crucible for holding molten silicon, and the surface of the molten silicon is coplanar with the first plane.

8. The monocrystalline silicon production equipment according to claim 7, characterized in that, The crucible is movably connected to the single crystal furnace along the height direction of the single crystal furnace.

9. A method for adjusting the magnetic field of a superconducting magnet, characterized in that, The method of using a superconducting magnet as described in any one of claims 1-5 includes the following steps: The first and second coils in the superconducting magnetic assembly are connected in series in the power supply circuit of the corresponding power source, so that the current in the first and second coils is in opposite directions; While ensuring that the total current of at least two first coils is I, the output current of each power supply is controlled so that in any two adjacent first coils, the current of the first coil near the first plane is always less than the current of the first coil far from the second plane. By adjusting the output current of each power source, different current ratios can be obtained between any two adjacent first coils, thus forming hook-shaped magnetic fields of different shapes.

10. The method for adjusting the magnetic field of a superconducting magnet according to claim 9, characterized in that, There are two superconducting magnetic groups and two power sources. Among the two first coils, the current of the first coil adjacent to the first plane is 0.5I-α, and the current of the first coil farther from the second plane is 0.5I+α, where 0<α≤0.25I.

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