Coil assembly of CUSP superconducting magnetic field generating device for crystal pulling of single crystal furnace

Abstract

The utility model belongs to the technical field of auxiliary equipment for crystal pulling and growth of single crystal furnaces, and particularly relates to a coil assembly of a CUSP superconducting magnetic field generating device for crystal pulling of a single crystal furnace, which comprises a coil framework and two coil groups, the inner layer coils of the two coil groups are connected in series and are connected with the same external direct-current power supply, and the outer layer coils of the two coil groups are connected in series and are connected with the other external direct-current power supply. According to the utility model, the position of a zero magnetic surface and the size of a magnetic field can be adjusted by controlling the size and the direction of the current of each layer of coil, so that the requirements of different single crystal pulling processes can be well met. According to the utility model, the superconducting magnetic field generating device can effectively inhibit the fluctuation of silicon melt under most working conditions, reduce the oxygen content of monocrystalline silicon crystals, improve the impurity uniformity of the monocrystalline silicon crystals and remarkably improve the quality of silicon wafers, and is scientific and reasonable in design, compact in structure, safe and reliable.

Description

Technical Field

[0001] The utility model belongs to the technical field of single crystal furnace crystal pulling growth auxiliary equipment, in particular to a coil component of a CUSP superconducting magnetic field generating device for single crystal furnace crystal pulling. Background Art

[0002] With the rapid development of Czochralski single crystal technology, mainstream single crystal manufacturers are increasingly increasing the size of their single crystal ingots to enhance their market competitiveness. Larger silicon ingots require larger crucibles and more material. The more silicon solution in the crucible, the greater the fluctuations in the solution under the influence of the thermal field. Furthermore, during the crystal pulling process, the silicon solution level slowly drops. To maintain a relative height that matches the crystal pulling process, crystal pullers have traditionally used a method of synchronously raising the crucible. However, this crucible raising inevitably exacerbates silicon solution fluctuations. The combined effects of these two factors lead to dramatic fluctuations in the silicon solution, which can negatively impact wafer quality, particularly the oxygen content and impurity uniformity within the wafers.

[0003] To improve the quality of single crystal growth in single crystal furnaces, existing technologies employ CUSP superconducting magnetic field generators to suppress fluctuations in the silicon solution within the furnace. Different crystal pulling process requirements may require the superconducting magnetic field generator to produce different zero magnetic plane positions and magnetic field magnitudes. However, the coil assemblies in existing CUSP superconducting magnetic field generators are often unable to adjust these positions and magnitudes. Utility Model Content

[0004] In view of the above problems, the purpose of the present invention is to provide a coil assembly for a CUSP superconducting magnetic field generating device for crystal pulling in a single crystal furnace.

[0005] The purpose of this utility model is achieved through the following technical solutions:

[0006] A coil assembly of a CUSP superconducting magnetic field generating device for crystal pulling in a single crystal furnace comprises a coil skeleton and two coil groups, each of the coil groups being divided into an inner coil and an outer coil, the inner coil of each coil group being wound around the coil skeleton, the outer coil of each coil group being arranged on the outer periphery of the inner coil of the same coil group, the arrangement positions of the inner coils of the two coil groups corresponding to each other in upper and lower directions, the arrangement positions of the outer coils of the two coil groups also corresponding to each other in upper and lower directions, the inner coils of the two coil groups being connected in series with each other and connected to the same external DC power supply, and the outer coils of the two coil groups being connected in series with each other and connected to another external DC power supply.

[0007] The coil frame is provided with an annular coil mounting groove, and each coil group is respectively arranged in a corresponding annular coil mounting groove.

[0008] The outer circumference of the inner coil of each coil group is wrapped with at least one full circle of low-temperature insulation tape, and the outer coil of each coil group is wound on the low-temperature insulation tape on the outer circumference of the inner coil of the same coil group.

[0009] The outer periphery of the outer coil of each coil group is wrapped with a binding.

[0010] The inner coils of each coil group are connected in parallel with a plurality of quench protection modules, and the outer coils of each coil group are also connected in parallel with a plurality of quench protection modules.

[0011] All the quench protection modules are mounted on the outside of the coil frame by bolts.

[0012] The advantages and positive effects of this utility model are:

[0013] 1. The utility model controls two independent external DC power supplies to pass forward or reverse current to the inner coil and outer coil of the two coil groups respectively. By controlling the current size and direction of each layer of coil, the zero magnetic surface position and magnetic field size can be adjusted, thereby adapting well to different single crystal pulling process requirements.

[0014] 2. The utility model enables the superconducting magnetic field generating device to effectively suppress the fluctuation of silicon melt, reduce the oxygen content of single crystal silicon crystals, and improve the impurity uniformity of single crystal silicon crystals under most working conditions, which can significantly improve the quality of silicon wafers. It has a scientific and reasonable design, a compact structure, and is safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of the utility model in a superconducting magnetic field generating device;

[0016] Figure 2 for Figure 1 Enlarged view of point A.

[0017] In the figure: 1 is the coil skeleton, 101 is the annular coil installation groove, 2 is the coil group, 201 is the inner coil, 202 is the outer coil, and 3 is the binding. DETAILED DESCRIPTION

[0018] The following is combined with Figure 1-2 The utility model is further described in detail.

[0019] A coil assembly of a CUSP superconducting magnetic field generating device for single crystal furnace pulling, such as Figure 1-2As shown, this embodiment includes a coil bobbin 1, the installation structure of the coil bobbin 1 in the superconducting magnetic field generating device adopts existing technology; it also includes two coil groups 2, each of which is divided into an inner coil 201 and an outer coil 202. The inner coil 201 of each coil group 2 is wound on the coil bobbin 1, and the outer coil 202 of each coil group 2 is arranged around the outer periphery of the inner coil 201 of the same coil group 2. The inner coils 201 of the two coil groups 2 are arranged in a vertically corresponding position, and the outer coils 202 of the two coil groups 2 are also arranged in a vertically corresponding position. The inner coils 201 of the two coil groups 2 are connected in series and connected to the same external DC power supply, and the outer coils 202 of the two coil groups 2 are connected in series and connected to another external DC power supply. The two external DC power supplies in this embodiment can both adopt the existing technology of programmable power supply modules, which can achieve high precision and high efficiency while also being small and light. In this embodiment, the connection method between the two coil assemblies 2 and the cryogenic vacuum system of the superconducting magnetic field generating device for providing vacuum and low-temperature conditions adopts existing technology. The cryogenic vacuum system generally includes a refrigerator, a vacuum dewar, a cold plate, a cold shield, and a tie rod. The refrigerator is the core of the cryogenic vacuum system, providing a cold source for the entire magnet. The vacuum dewar is responsible for maintaining the vacuum and low-temperature conditions required for magnet operation. The cold plate transfers the cold energy from the refrigerator to the coil assembly and the cold shield. The cold shield is used to reduce the radiative heat leakage of the coil assembly to the external environment. The coil assembly and the cold shield are both positioned and fixed by the tie rods on the vacuum dewar. The vacuum dewar is equipped with lifting lugs, which can be used to lift the equipment during installation and transportation. In this embodiment, the specific number of turns of the outer coils 202 of the two coil assemblies 2 is substantially the same, and the specific number of turns of the outer coils 202 of the two coil assemblies 2 is also substantially the same, or can be arbitrarily adjusted according to specific usage requirements.

[0020] Specifically, the outer circumference of the inner coil 201 of each coil assembly 2 is wrapped with at least one full turn of low-temperature insulating tape (omitted in the accompanying drawings). The outer coil 202 of each coil assembly 2 is wound around the outer circumference of the inner coil 201 of the same coil assembly 2. In this embodiment, the low-temperature insulating tape is commercially available. By placing low-temperature insulating tape between the inner coil 201 and the outer coil 202, good insulation between the inner coil 201 and the outer coil 202 is ensured, preventing interlayer breakdown and ensuring the insulation performance of the coil assembly 2.

[0021] like Figure 2 As shown, each coil assembly 2 has its outer coil 202 wrapped with a binding 3. In this embodiment, the binding 3 utilizes existing technology. By providing the outer coil 202 with binding 3, a preload is applied to the coil assembly 2, effectively preventing displacement due to thermal expansion and contraction.

[0022] In this embodiment, the coil bobbin 1 is provided with an annular coil mounting groove 101. Each coil assembly 2 is positioned in a corresponding annular coil mounting groove 101, facilitating the positioning, support, and installation of the coil assembly 2. When winding each coil assembly 2, the conductive wire of the inner coil 201 is first wound into the annular coil mounting groove 101 of the coil bobbin 1. Low-temperature insulation tape is then wrapped around the outer surface of the inner coil 201. The conductive wire of the outer coil 202 is then wrapped around this low-temperature insulation tape. Finally, a pre-tightened binding 3 is wrapped around the outer surface of the outer coil 202. The annular coil mounting groove 101 simultaneously supports and protects the inner coil 201, the outer coil 202, and the binding 3.

[0023] Specifically, in the present embodiment, the inner coil 201 of each coil group 2 is all connected in parallel with several quench protection modules, and the outer coil 202 of each coil group 2 is also all connected in parallel with several quench protection modules. In the present embodiment, the quench protection module also all adopts the quench protection module structure of prior art, and the quantity of the quench protection modules in parallel is determined by the coil stored energy. All quench protection modules are all installed on the outside of the coil bobbin 1 by bolts, and disassembly and maintenance are easy. By the setting of the quench protection module, each layer of coil can be independently carried out quench protection, ensure that when magnet quench occurs, most of the energy is discharged by the quench protection module, reduce the local maximum voltage and temperature when the magnet quenches, in order to avoid permanent damage to the magnet.

[0024] Working principle:

[0025] When in use, by controlling two independent external DC power supplies, forward or reverse current can be passed through the inner coil 201 and the outer coil 202 of the two coil groups 2 respectively, wherein the current magnitude and direction of the outer coil 202 of the two coil groups 2 are the same, and the current magnitude and direction of the inner coil 201 of the two coil groups 2 are the same. By controlling the current magnitude and direction of each layer of coil, the zero magnetic surface position and the magnetic field magnitude can be adjusted to meet different crystal pulling process requirements.

Claims

1. A coil assembly for a CUSP superconducting magnetic field generator for a single crystal furnace, comprising a coil skeleton (1), characterized in that: The invention also comprises two coil groups (2), each of the coil groups (2) being divided into an inner coil (201) and an outer coil (202), the inner coil (201) of each coil group (2) being wound on the coil frame (1), the outer coil (202) of each coil group (2) being arranged on the outer periphery of the inner coil (201) of the same coil group (2), the arrangement positions of the inner coils (201) of the two coil groups (2) corresponding to each other up and down, and the arrangement positions of the outer coils (202) of the two coil groups (2) also corresponding to each other up and down, the inner coils (201) of the two coil groups (2) being connected in series with each other and connected to the same external DC power supply, and the outer coils (202) of the two coil groups (2) being connected in series with each other and connected to another external DC power supply.

2. The coil assembly of the CUSP superconducting magnetic field generator for single crystal furnace pulling according to claim 1, characterized in that: An annular coil mounting groove (101) is provided on the coil frame (1), and each coil group (2) is respectively arranged in a corresponding annular coil mounting groove (101).

3. The coil assembly of the CUSP superconducting magnetic field generator for single crystal furnace pulling according to claim 1, characterized in that: The outer circumference of the inner coil (201) of each coil group (2) is wound with at least one full circle of low-temperature insulating tape, and the outer coil (202) of each coil group (2) is wound on the low-temperature insulating tape on the outer circumference of the inner coil (201) of the same coil group (2).

4. The coil assembly of the CUSP superconducting magnetic field generator for single crystal furnace pulling according to claim 1, characterized in that: The outer periphery of the outer coil (202) of each coil group (2) is further wound with a binding (3).

5. The coil assembly of the CUSP superconducting magnetic field generator for single crystal furnace pulling according to claim 1, characterized in that: The inner coil (201) of each coil group (2) is connected in parallel with a plurality of quench protection modules, and the outer coil (202) of each coil group (2) is also connected in parallel with a plurality of quench protection modules.

6. The coil assembly of the CUSP superconducting magnetic field generator for single crystal furnace pulling according to claim 5, characterized in that: All the quench protection modules are mounted on the outside of the coil frame (1) by means of bolts.

Images