Superconducting magnet and single crystal silicon production apparatus

Abstract

The application discloses a superconducting magnet and a single crystal silicon production device. The superconducting magnet comprises a first superconducting magnetic group and a second superconducting magnetic group for forming a hook-shaped magnetic field. The first superconducting magnetic group comprises two first coils which are arranged at intervals along the axial direction of the first coils and are symmetrically arranged relative to a first plane. The second superconducting magnetic group comprises two second coils which are both located between the two first coils and are symmetrically arranged relative to the first plane. The number of turns of the second coils is less than that of the first coils. The superconducting magnet has the advantages that the convection of the silicon melt is better inhibited, and the oxygen content of the drawn single crystal rod is low.

Description

Technical Field

[0001] This invention relates to the field of superconducting magnet technology, specifically to a superconducting magnet and a single-crystal silicon production equipment. 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] According to an embodiment of the present invention, a superconducting magnet includes a first superconducting magnetic group and a second superconducting magnetic group for forming a hook-shaped magnetic field. The first superconducting magnetic group includes two first coils, which are arranged at intervals along the axial direction of the first coils and are symmetrically arranged with respect to a first plane. The second superconducting magnetic group includes two second coils, which are located between the two first coils and are symmetrically arranged with respect to the first plane. The number of turns of the second coils is less than the number of turns of the first coils.

[0008] According to the superconducting magnet of the present invention, the number of turns of the two second coils closer to the first plane is less than the number of turns of the two first coils farther from the first plane. As a result, in the new hook-shaped magnetic field formed by the superposition of the hook-shaped magnetic field formed by the two first coils and the hook-shaped magnetic field formed by the two second coils, a larger magnetic field component perpendicular to the crucible wall can be formed at a position farther away from the first plane. That is, it 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, which effectively prevents oxygen molecules from entering the silicon melt from the crucible. The resulting single crystal rod has a lower oxygen content and better quality.

[0009] In some embodiments, the superconducting magnet includes a power source, with the two first coils and the two second coils connected in series in the power supply circuit of the power source.

[0010] In some embodiments, the number of turns of the first coil is W+α, and the number of turns of the second coil is W-α, where 0<α≤0.5W.

[0011] In some embodiments, the first coil and the second coil are arranged axially spaced along the first coil, with the second coil located above the first plane adjacent to the first coil located above the first plane.

[0012] In some embodiments, the superconducting magnet further includes a first shaft and a second shaft respectively disposed above and below the first plane. The first coil and the second coil located above the first plane are both wound on the first shaft, and the first coil and the second coil located below the first plane are both wound on the second shaft. The first shaft and the second shaft are both cylindrical structures and are adapted to be sleeved on the outer periphery of the single crystal furnace.

[0013] In some embodiments, 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 the first coil and the second coil on the first shaft, and the second partition is located between the first coil and the second coil on the second shaft.

[0014] In some embodiments, both the first partition and the second partition are insulating ring plates.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] In some embodiments, the crucible is movably connected to the single crystal furnace along the height direction of the single crystal furnace. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of monocrystalline silicon production equipment in related technologies.

[0020] Figure 2 This is a schematic diagram of a monocrystalline silicon production equipment according to an embodiment of the present invention.

[0021] 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.

[0022] Figure label:

[0023] 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

[0024] 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.

[0025] The following is combined with Figures 1-3 A superconducting magnet according to an embodiment of the present invention is described.

[0026] The superconducting magnet according to an embodiment of the present invention includes a first superconducting magnetic group and a second superconducting magnetic group for forming a hook-shaped magnetic field 7. The first superconducting magnetic group includes two first coils 1, which are spaced apart along the axial direction of the first coils 1 and are symmetrically arranged with respect to a first plane 52. The second superconducting magnetic group includes two second coils 2, which are located between the two first coils 1 and are symmetrically arranged with respect to the first plane 52. The number of turns of the second coils 2 is less than the number of turns of the first coils 1.

[0027] According to the superconducting magnet of the present invention, the number of turns of the two second coils 2 closer to the first plane 52 is less than the number of turns of the two first coils 1 farther from the first plane 52. As a result, in the new hook-shaped magnetic field 7 formed by the superposition of the hook-shaped magnetic field 7 formed by the two first coils 1 and the hook-shaped magnetic field 7 formed by the two second coils 2, a larger magnetic field component perpendicular to the wall of the crucible 5 can be formed at a position farther 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.

[0028] It should be noted that in the related technology, the number of turns in each of the two coils is the sum of the number of turns in the first coil 1 and the second coil 2. That is, in this embodiment, the coils in the related technology are divided into a first coil 1 and a second coil 2 with different numbers of turns. Furthermore, when the superconducting magnet is working, the currents in the two first coils 1 are the same but in opposite directions, and the currents in the two second coils 2 are the same but in opposite directions. For example... 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 suppress convection at the bottom of the silicon melt 51.

[0029] In some embodiments, the superconducting magnet includes a power source (not shown), with two first coils 1 and two second coils 2 connected in series in the power supply circuit of the power source.

[0030] This means that only one power supply is needed for excitation to ensure that the current in the first coil 1 and the second coil 2 is the same, thereby eliminating the need for a power supply and simplifying external excitation control. At the same time, the hook-shaped magnetic field 7 formed in this state can achieve a greater convection suppression effect on the silicon melt 51.

[0031] Specifically, the power supply is a DC power supply.

[0032] It should be noted that excitation refers to the magnetic field strength required for the growth of semiconductor single crystal silicon, which is increased from the Earth's magnetic field strength when the first coil 1 and the second coil 2 are powered by the power supply.

[0033] In some embodiments, the number of turns of the first coil 1 is W+α, and the number of turns of the second coil 2 is W-α, where 0<α≤0.5W.

[0034] Compared to the hook-shaped magnetic field 7 in related technologies, the hook-shaped magnetic field 7 formed within the above range can always better achieve the convection suppression effect on the silicon melt 51, ensuring the quality of the pulled single crystal rod 53.

[0035] Specifically, in the related technology, the total number of turns of each of the two coils is 2W. The number of turns of the first coil 1 can be 1.5W, 1.25W, and 1.1W, etc., and correspondingly, the number of turns of the second coil 2 can be 0.5W, 0.75W, and 0.9W, etc.

[0036] In some embodiments, the first coil 1 and the second coil 2 are arranged at an axial distance from the first coil 1, with the second coil 2 located above the first plane 52 adjacent to the first coil 1 located above the first plane 52.

[0037] Specifically, the first coil 1 and the second coil 2 located above the first plane 52 are connected in series by a wire, and the first coil 1 and the second coil 2 located below the first plane 52 are also connected in series by a wire. In this case, the first coil 1 located on the same side of the first plane 52 is adjacent to the second coil 2, which facilitates the electrical connection between the two. At the same time, the spaced arrangement of the first coil 1 and the second coil 2 also avoids short circuits caused by contact between the two at other locations, ensuring the stability of the finally formed hook-shaped magnetic field 7.

[0038] In some embodiments, the superconducting magnet further includes a first axis and a second axis respectively disposed above and below the first plane 52. The first coil 1 and the second coil 2 located above the first plane 52 are both wound on the first axis, and the first coil 1 and the second coil 2 located below the first plane 52 are both wound on the second axis. The first axis and the second axis are both cylindrical structures and are adapted to be sleeved on the outer periphery of the single crystal furnace 6.

[0039] That is, the inner diameter of the first coil 1 is equal to the inner diameter of the second coil 2. At this time, the first coil 1 and the second coil 2, which are located on the same side of the first plane 52, are both wound on the same axis, which ensures the positional stability of the first coil 1 and the second coil 2, thereby ensuring the stability of the formed hook-shaped magnetic field 7 and ensuring the stable suppression effect on the silicon melt 51.

[0040] Specifically, the first and second axes have the same structure and are arranged symmetrically relative to the first plane 52. After the first coil 1 is wound on the first axis, the second coil 2 can be wound directly. At this time, the first coil 1 and the second coil 2 are automatically connected in series, which makes the later assembly of the superconducting magnet easier.

[0041] In some embodiments, such as Figure 2 As shown, 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 the first coil 1 and the second coil 2 on the first shaft, and the second partition 4 is located between the first coil 1 and the second coil 2 on the second shaft.

[0042] The first partition 3 separates the first coil 1 and the second coil 2 located on the first axis, and the second partition 4 separates the first coil 1 and the second coil 2 located on the second axis, thereby effectively preventing the first coil 1 and the corresponding second coil 2 from accidentally contacting and short-circuiting, which would affect the formation of the hook-shaped magnetic field 7.

[0043] 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 first coil 1 and the second coil 2 on the first shaft, and the second partition 4 provides better separation and insulation for the first coil 1 and the second coil 2 on the second shaft.

[0044] 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 first coil 1.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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 first superconducting magnetic assembly for forming a hook-shaped magnetic field, the first superconducting magnetic assembly includes two first coils, the two first coils are arranged at intervals along the axial direction of the first coils, and the two first coils are arranged symmetrically with respect to a first plane; and A second superconducting magnetic assembly for forming a hook-shaped magnetic field, the second superconducting magnetic assembly includes two second coils, both of which are located between two first coils. The two second coils are arranged symmetrically with respect to the first plane, and the number of turns of the second coils is less than the number of turns of the first coils. The superconducting magnet includes a power source, with the two first coils and the two second coils connected in series in the power supply circuit of the power source; The number of turns of the first coil is W+α, and the number of turns of the second coil is W-α, where 0<α≤0.5W.

2. The superconducting magnet according to claim 1, characterized in that, The first coil and the second coil are arranged at an axial distance along the first coil, with the second coil located above the first plane adjacent to the first coil located above the first plane.

3. The superconducting magnet according to claim 2, characterized in that, The superconducting magnet also includes a first shaft and a second shaft respectively disposed above and below the first plane. The first coil and the second coil located above the first plane are both wound on the first shaft, and the first coil and the second coil located below the first plane are both wound on the second shaft. The first shaft and the second shaft are both cylindrical structures and are suitable for being sleeved on the outer periphery of the single crystal furnace.

4. The superconducting magnet according to claim 3, characterized in that, The first shaft has a first partition plate on its outer periphery, and the second shaft has a second partition plate on its outer periphery. The first partition plate is located between the first coil and the second coil on the first shaft, and the second partition plate is located between the first coil and the second coil on the second shaft.

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.

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