Superconducting magnet coil structure for large-size magnetic control czochralski silicon

Abstract

The utility model discloses a superconducting magnet coil structure for large-size magnetic control Czochralski monocrystalline silicon, which relates to the technical field of superconducting magnet magnetic control Czochralski monocrystalline silicon and comprises a magnetic shielding vacuum cavity, a solenoid CUSP superconducting coil, a saddle-shaped superconducting coil, a first current lead, a second current lead, a first superconducting power supply, a second superconducting power supply and a programmable controller. The solenoid CUSP superconducting coil is used for generating an axial magnetic field with the central area field intensity being zero and the upper area and the lower area being opposite in direction, and the saddle-shaped superconducting coil is used for generating a transverse magnetic field. The composite superconducting magnet coil structure is constructed by combining the solenoid CUSP superconducting coil and the saddle type superconducting coil, so that a composite magnetic field with high direction adjustment flexibility and high uniformity can be generated in the crucible for pulling the single crystal by adjusting the working current of the two superconducting coils; and the requirements of large-size magnetic control czochralski silicon such as 300mm silicon wafers and next-generation 450mm silicon wafers can be met.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of superconducting magnet magnetic control Czochralski single crystal technology, in particular to a superconducting magnet coil structure for large-size magnetic control Czochralski single crystal silicon. BACKGROUND

[0002] For the preparation of large-size silicon wafers, especially 300mm silicon wafers and the next generation of 450mm silicon wafers, the traditional single-current magnetic field controlled crystal quality has bottlenecks. The core pain point of the traditional magnetic control Czochralski silicon process lies in the control of the thermal convection of molten silicon. First, the electrical conductivity of molten silicon will significantly affect the effect of the magnetic field, and second, the crystal growth interface needs an extremely stable thermal environment. Although the traditional CUSP magnet can suppress axisymmetric convection, it cannot precisely control asymmetric turbulence, and the saddle-shaped coil is just the opposite. Therefore, the superconducting magnet coil structure for large-size magnetic control Czochralski single crystal silicon needs to be researched.

[0003] In the prior art, Chinese patent CN117524692A discloses a control circuit, a superconducting magnet and a magnetic control Czochralski crystal pulling device. The control circuit comprises: a superconducting coil in a ring structure, the superconducting coil comprising two independent coil parts, and the two coil parts being arranged opposite to each other; current leads, a group of current leads being electrically connected with the two coil parts respectively; and a power supply, electrically connected with the current leads, the power supply inputting excitation current to the superconducting coil to generate a magnetic field by the coil, and after the connection relationship between the current leads and the coil parts changes, the excitation current input by the power supply adjusts the magnetic field formed by each coil part as required.

[0004] However, the above prior art only adopts a saddle-shaped coil, although the magnetic field thereof is adjustable, but cannot generate a composite magnetic field with high flexibility of direction adjustment and high uniformity, and it is difficult to meet the demand of large-size magnetic control Czochralski single crystal silicon such as 300mm silicon wafers and the next generation of 450mm silicon wafers. Practical new type content

[0005] The application provides a superconducting magnet coil structure for large-size magnetic control Czochralski single crystal silicon, to solve the problem that the existing superconducting magnet magnetic control Czochralski single crystal technology cannot generate a composite magnetic field with high flexibility of direction adjustment and high uniformity, and it is difficult to meet the demand of large-size magnetic control Czochralski single crystal silicon such as 300mm silicon wafers and the next generation of 450mm silicon wafers.

[0006] In one aspect, the application provides a superconducting magnet coil structure for large-size magnetic control Czochralski single crystal silicon, comprising: a magnetic shielding vacuum cavity, a solenoid CUSP superconducting coil, a saddle-shaped superconducting coil, a first current lead, a second current lead, a first superconducting power supply, a second superconducting power supply and a programmable controller.

[0007] The magnetic shielding vacuum cavity is a concentric cylinder.

[0008] The solenoid CUSP superconducting coil comprises a solenoid CUSP first superconducting coil and a solenoid CUSP second superconducting coil, which are two annular solenoid CUSP coils symmetrically distributed up and down, and are fixedly arranged inside the magnetic shielding vacuum chamber.

[0009] The saddle type superconducting coil comprises a saddle type first superconducting coil and a saddle type second superconducting coil, which are two saddle type circular arc coils symmetrically distributed left and right, and are fixedly arranged inside the magnetic shielding vacuum chamber and between the solenoid CUSP first superconducting coil and the solenoid CUSP second superconducting coil.

[0010] The first current lead is a current lead of the solenoid CUSP superconducting coil, and the second current lead is a current lead of the saddle type superconducting coil, and the first current lead and the second current lead are both insulatively mounted on the top of the magnetic shielding vacuum chamber.

[0011] The solenoid CUSP first superconducting coil and the solenoid CUSP second superconducting coil are connected in series, one end of the solenoid CUSP first superconducting coil away from the solenoid CUSP second superconducting coil is connected to a positive electrode of a first current lead, and one end of the solenoid CUSP second superconducting coil away from the solenoid CUSP first superconducting coil is connected to a negative electrode of the first current lead.

[0012] The saddle type first superconducting coil and the saddle type second superconducting coil are connected in series, one end of the saddle type first superconducting coil away from the saddle type second superconducting coil is connected to a positive electrode of a second current lead, and one end of the saddle type second superconducting coil away from the saddle type first superconducting coil is connected to a negative electrode of the second current lead.

[0013] The first superconducting power supply is respectively connected to the positive electrode of the first current lead and the negative electrode of the first current lead, and the second superconducting power supply is respectively connected to the positive electrode of the second current lead and the negative electrode of the second current lead.

[0014] The programmable controller is in communication connection and / or electrical connection with the first superconducting power supply and the second superconducting power supply.

[0015] The solenoid CUSP superconducting coil is used to generate an axial magnetic field with zero central area field strength and opposite directions in the upper and lower areas, and the saddle type superconducting coil is used to generate a transverse magnetic field.

[0016] In a possible implementation, the programmable controller is in communication connection and / or electrical connection with a monitor.

[0017] In a possible implementation, the number of the first current lead and the second current lead is one set, and each set has two.

[0018] In a possible implementation, the solenoid CUSP superconducting coil is wound with NbTi superconducting wire, and the NbTi superconducting wire is coated with a polyimide insulating layer.

[0019] In a possible implementation, the solenoid CUSP superconducting coil is wound in a layered and dense manner, glass cloth insulation is used between layers, and epoxy resin is used for curing.

[0020] In a possible implementation, the inner diameter of the solenoid CUSP superconducting coil is greater than the outer diameter of the crucible, and the bending radius of the saddle-shaped superconducting coil matches the distance from the center of the crucible to the saddle-shaped superconducting coil.

[0021] In a possible implementation, the center plane of the solenoid CUSP superconducting coil coincides with the center plane of the saddle-shaped superconducting coil.

[0022] The superconducting magnet coil structure for large-size magnetic control Czochralski silicon in the application has the following advantages:

[0023] By combining the solenoid CUSP superconducting coil and the saddle-shaped superconducting coil to construct a composite superconducting magnet coil structure, the working current of the two types of superconducting coils can be adjusted to generate a composite magnetic field in the crucible for growing single crystals, which has high direction adjustment flexibility and high uniformity, and can meet the needs of large-size magnetic control Czochralski silicon such as 300 mm silicon wafers and the next generation of 450 mm silicon wafers.

[0024] In the field of magnetic control Czochralski technology, it can provide three-dimensional convection suppression effect, solve the problem of complex turbulent flow of large-size melt, accurately control the oxygen content to meet the requirements of semiconductor-grade high-purity silicon, realize the growth of ultra-stable silicon crystal interface, improve the integrity of the crystal, and reduce the defect density, and support the growth of 450 mm silicon wafers, breaking through the bottleneck of future technology nodes.

[0025] In the field of superconducting magnets, a highly uniform and directionally controllable magnetic field is synthesized in the target area, especially the central area. The ability to effectively combine the axial magnetic field generated by the solenoid CUSP superconducting coil and the transverse magnetic field generated by the saddle-shaped superconducting coil improves the space utilization and compactness of the entire magnet system, and provides stronger dynamic adjustment flexibility of the magnetic field. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0027] Figure 1 A large-size magnetic control Czochralski silicon superconducting magnet coil structure schematic diagram is provided for the embodiments of the present application;

[0028] Figure 2 A large-size magnetic control Czochralski silicon superconducting magnet coil structure circuit connection schematic diagram is provided for the embodiments of the present application;

[0029] Figure 3 A large-size magnetic control Czochralski silicon superconducting magnet coil structure magnetic field configuration schematic diagram is provided for the embodiments of the present application.

[0030] Explanation of reference signs:

[0031] 101-magnetic shielding vacuum chamber, 1021-solenoid CUSP first superconducting coil, 1022-solenoid CUSP second superconducting coil, 1031-saddle type first superconducting coil, 1032-saddle type second superconducting coil, 1041-first current lead positive, 1042-first current lead negative, 1051-second current lead positive, 1052-second current lead negative, 2011-first superconducting power supply, 2012-second superconducting power supply, 202-programmable controller, 203-monitor. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0033] As shown in Figure 1 , Figure 2 The embodiments of the present application provide a large-size magnetic control Czochralski silicon superconducting magnet coil structure, which comprises a magnetic shielding vacuum chamber 101, a solenoid CUSP superconducting coil, a saddle type superconducting coil, a first current lead, a second current lead, a first superconducting power supply 2011, a second superconducting power supply 2012, and a programmable controller 202.

[0034] The magnetic shielding vacuum chamber 101 is a concentric cylinder.

[0035] The solenoid CUSP superconducting coil comprises a solenoid CUSP first superconducting coil 1021 and a solenoid CUSP second superconducting coil 1022, which are two annular solenoid CUSP coils symmetrically distributed above and below, and the solenoid CUSP superconducting coil is fixedly arranged inside the magnetic shielding vacuum chamber 101.

[0036] The saddle-shaped superconducting coil includes a saddle-shaped first superconducting coil 1031 and a saddle-shaped second superconducting coil 1032, which are two left-right symmetrical saddle-shaped circular arc coils, and is fixedly arranged inside the magnetic shielding vacuum chamber 101 and between the solenoid CUSP first superconducting coil 1021 and the solenoid CUSP second superconducting coil 1022.

[0037] The first current lead is a current lead of the solenoid CUSP superconducting coil, and the second current lead is a current lead of the saddle-shaped superconducting coil, and the first current lead and the second current lead are both insulated and mounted on the top of the magnetic shielding vacuum chamber 101.

[0038] The solenoid CUSP first superconducting coil 1021 and the solenoid CUSP second superconducting coil 1022 are connected in series, and the end of the solenoid CUSP first superconducting coil 1021 away from the solenoid CUSP second superconducting coil 1022 is connected to the first current lead positive electrode 1041, and the end of the solenoid CUSP second superconducting coil 1022 away from the solenoid CUSP first superconducting coil 1021 is connected to the first current lead negative electrode 1042.

[0039] The solenoid CUSP first superconducting coil 1021 and the solenoid CUSP second superconducting coil 1022 are connected in series, and the end of the solenoid CUSP first superconducting coil 1021 away from the solenoid CUSP second superconducting coil 1022 is connected to the first current lead positive electrode 1041, and the end of the solenoid CUSP second superconducting coil 1022 away from the solenoid CUSP first superconducting coil 1021 is connected to the first current lead negative electrode 1042.

[0040] The first superconducting power supply 2011 is respectively connected to the first current lead positive electrode 1041 and the first current lead negative electrode 1042, and the second superconducting power supply 2012 is respectively connected to the second current lead positive electrode 1051 and the second current lead negative electrode 1052.

[0041] The programmable controller 202 is respectively connected to the first superconducting power supply 2011 and the second superconducting power supply 2012 in communication and / or electrical connection.

[0042] The solenoid CUSP superconducting coil is used to generate an axial magnetic field with zero central area field strength and opposite directions in the upper and lower areas, and the saddle-shaped superconducting coil is used to generate a transverse magnetic field.

[0043] Specifically, in this embodiment, the inside of the vacuum chamber of the magnetic shielding vacuum chamber 101 is a vacuum sealed environment, and the outer wall is a magnetic conductive material to reduce external leakage magnetic field.

[0044] In the embodiment, the solenoid CUSP superconducting coil is wound on the coil support cylinder, and the saddle type superconducting coil is mechanically fixed on the support frame, both of which adopt existing superconducting coil fixing technology, which will not be described in detail here.

[0045] In the embodiment, the programmable controller 202 is in communication connection with the first superconducting power supply 2011 and the second superconducting power supply 2012 respectively.

[0046] By accurately designing the geometric size, position and current ratio of the two coils, the axial magnetic field (Bz) and the transverse magnetic field (Bx / By) can be vector superimposed in a specific region in space. This makes it possible to generate a composite magnetic field with adjustable direction and high uniformity in the target region (single crystal crucible region).

[0047] For the single crystal furnace crucible region of 300mm / 450mm single crystal silicon rod preparation, the composite magnetic field uniform region of the composite superconducting magnet completely covers the melt and the crystal growth interface in the crucible.

[0048] Exemplarily, the programmable controller 202 is in communication connection and / or electrical connection with a monitor 203.

[0049] Specifically, in the embodiment, the monitor 203 is in communication connection with the programmable controller 202.

[0050] Exemplarily, the number of the first current lead and the second current lead is one set, and each set has two.

[0051] Exemplarily, the solenoid CUSP superconducting coil is wound with NbTi superconducting wire, and the NbTi superconducting wire is coated with a polyimide insulation layer.

[0052] Exemplarily, the winding structure of the solenoid CUSP superconducting coil is layered and densely wound, glass cloth insulation is used between layers, and epoxy resin is used for curing.

[0053] Exemplarily, the inner diameter of the solenoid CUSP superconducting coil is greater than the outer diameter of the crucible, and the bending radius of the saddle type superconducting coil matches the distance from the center of the crucible to the saddle type superconducting coil.

[0054] Specifically, a thermal insulation layer and a mechanical support space are reserved between the solenoid CUSP superconducting coil and the crucible. The span between the saddle type superconducting coil and the crucible ensures the uniformity of the transverse magnetic field in the height direction of the crucible.

[0055] Exemplarily, the center plane of the solenoid CUSP superconducting coil coincides with the center plane of the saddle type superconducting coil.

[0056] Specifically, the center plane of the solenoid CUSP superconducting coil (i.e. the plane where the crucible solid-liquid interface is located) coincides with the center plane of the saddle superconducting coil, ensuring the uniformity of the transverse magnetic field in the key area.

[0057] In the present embodiment, the two ends of the solenoid CUSP superconducting coil are connected to the axial support column through annular flanges, and each coil of the axial magnetic field is fixed on the annular support of the inner wall of the solenoid CUSP superconducting coil through 4 radial support arms.

[0058] By independently controlling the current of the solenoid CUSP superconducting coil and the saddle superconducting coil through power supply, the direction of the composite magnetic field is adjustable and the uniformity is optimized.

[0059] Specifically, in the present embodiment, the application process of the superconducting magnet coil structure for large-size magnetic control Czochralski single crystal silicon is as follows:

[0060] During the operation of the single crystal furnace, according to the silicon rod specifications (300mm / 450mm) and the crystal growth stage (seed introduction, shoulder release, constant diameter), the magnetic field mode is preset. The seed introduction stage is the initial stage of single crystal silicon growth, and the goal is to form a defect-free seed to lay the foundation for subsequent crystal growth. At this time, the transverse magnetic field (Bx / By) is dominant, and the initial convection of the melt is inhibited by the strong damping of the Lorentz force, and the zero-field center of the CUSP axial magnetic field is used to avoid dislocation generation when the seed is contacted. The angle between the composite magnetic field and the axial magnetic field (Bz) is controlled at 60°-90°, that is, the saddle superconducting coil generates a rated magnetic field, and the solenoid CUSP superconducting coil generates a smaller or no magnetic field. The magnetic field is mainly the transverse component, which inhibits the convection of the melt and reduces the initial defects; the constant diameter stage is the growth stage of the single crystal silicon rod, and the goal is to balance the oxygen content and dislocation density, and to ensure the radial uniformity. At this time, the composite magnetic field (Bz and Bx / By) needs to consider multiple requirements: therefore, the angle between the composite magnetic field and the axial magnetic field (Bz) is controlled at 30°-45°, that is, both the saddle superconducting coil and the solenoid CUSP superconducting coil need to generate a magnetic field to balance the oxygen content and dislocation density, and to ensure the uniformity of the single crystal silicon melt pool.

[0061] The programmable controller 202 is realized by monitoring the monitor 203 to achieve the composite magnetic field instruction, the programmable controller 202 outputs the axial magnetic field component working current required by the composite magnetic field to the first superconducting power supply 2011, and outputs the transverse magnetic field component working current to the second superconducting power supply 2012. The positive and negative poles of the first superconducting power supply 2011 are connected to the positive pole of the first current lead 1041 and the negative pole of the first current lead 1042 respectively, and the solenoid CUSP superconducting coil in the superconducting magnet is energized to generate a magnetic field at a constant speed, and when the working current is reached, it is kept stable. The positive and negative poles of the second superconducting power supply 2012 are connected to the positive pole of the second current lead 1051 and the negative pole of the second current lead 1052 respectively, and the saddle-shaped superconducting coil in the superconducting magnet is energized to generate a magnetic field at a constant speed, and when the working current is reached, it is kept stable. The magnetic field configuration of the composite magnetic field generated by the two coils together is as shown in the figure. Figure 3

[0062] The embodiment of the present application combines the solenoid CUSP superconducting coil and the saddle-shaped superconducting coil to construct a composite superconducting magnet coil structure. By adjusting the working currents of the two superconducting coils, a composite magnetic field with high direction adjustment flexibility and high uniformity can be generated in the crucible for pulling single crystals, which can meet the needs of large-size magnetic control Czochralski silicon such as 300mm silicon wafer and next-generation 450mm silicon wafer.

[0063] In the aspect of magnetic control Czochralski single crystal technology, it can provide three-dimensional convection suppression effect, solve the problem of complex turbulent flow of large-size melt, accurately control the oxygen content to meet the requirements of semiconductor-grade high-purity silicon, realize the growth of ultra-stable silicon crystal interface, improve the integrity of the crystal and reduce the defect density, and support the growth of 450mm silicon wafer, breaking through the bottleneck of future technology nodes.

[0064] In the aspect of superconducting magnet, a highly uniform and direction-controllable magnetic field is synthesized in the target area (especially the central area). The ability to effectively combine the axial magnetic field generated by the solenoid CUSP superconducting coil and the transverse magnetic field generated by the saddle-shaped superconducting coil improves the space utilization and compactness of the entire magnet system, and provides stronger dynamic adjustment flexibility of the magnetic field.

[0065] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0066] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.​

Claims

1. A superconducting magnet coil structure for large-size magnetic -control Czochralski single crystal silicon, characterized by comprising: The application relates to a magnetic shielding vacuum chamber, a solenoid CUSP superconducting coil, a saddle type superconducting coil, a first current lead, a second current lead, a first superconducting power supply, a second superconducting power supply and a programmable controller. The magnetic shielding vacuum chamber is a concentric cylinder. The solenoid CUSP superconducting coil comprises a solenoid CUSP first superconducting coil and a solenoid CUSP second superconducting coil, and is two annular solenoid CUSP coils which are symmetrically distributed upwards and downwards; the solenoid CUSP superconducting coil is fixedly arranged in the interior of the magnetic shielding vacuum chamber. The saddle type superconducting coil comprises a saddle type first superconducting coil and a saddle type second superconducting coil, and is two horse-saddle circular arc type coils which are symmetrically distributed leftwards and rightwards; the saddle type superconducting coil is fixedly arranged in the interior of the magnetic shielding vacuum chamber and is located between the solenoid CUSP first superconducting coil and the solenoid CUSP second superconducting coil. The first current lead is a current lead of the solenoid CUSP superconducting coil, the second current lead is a current lead of the saddle type superconducting coil, and the first current lead and the second current lead are both insulatively arranged on the top of the magnetic shielding vacuum chamber. The solenoid CUSP first superconducting coil and the solenoid CUSP second superconducting coil are connected in series; one end of the solenoid CUSP first superconducting coil, which is far away from the solenoid CUSP second superconducting coil, is connected with a positive pole of the first current lead; and one end of the solenoid CUSP second superconducting coil, which is far away from the solenoid CUSP first superconducting coil, is connected with a negative pole of the first current lead. The saddle type first superconducting coil and the saddle type second superconducting coil are connected in series; one end of the saddle type first superconducting coil, which is far away from the saddle type second superconducting coil, is connected with a positive pole of the second current lead; and one end of the saddle type second superconducting coil, which is far away from the saddle type first superconducting coil, is connected with a negative pole of the second current lead. The first superconducting power supply is connected with the positive pole and the negative pole of the first current lead respectively; and the second superconducting power supply is connected with the positive pole and the negative pole of the second current lead respectively. The programmable controller is in communication connection and / or electrical connection with the first superconducting power supply and the second superconducting power supply. The solenoid CUSP superconducting coil is used for generating an axial magnetic field with a central area field strength of zero and opposite directions in upper and lower areas; and the saddle type superconducting coil is used for generating a transverse magnetic field. The programmable controller is in communication connection and / or electrical connection with a monitor.

2. A superconducting magnet coil structure for large-size magnetic- control Czochralski silicon single crystal drawing apparatus according to claim 1, characterized by The number of the first current lead and the second current lead is one set, and each set is two.

3. The superconducting magnet coil structure for a large-size magnetic- control Czochralski silicon single crystal according to claim 1, characterized by The solenoid CUSP superconducting coil is wound by NbTi superconducting wire, and the NbTi superconducting wire is coated with a polyimide insulating layer.

4. The superconducting magnet coil structure for a large-size magnetic- control Czochralski silicon single crystal according to claim 1, characterized by The winding structure of the solenoid CUSP superconducting coil is layered and densely wound; glass silk cloth insulation is used between layers, and epoxy resin is used for curing.

5. The superconducting magnet coil structure for a large-size magnetic- control Czochralski silicon single crystal according to claim 1, characterized by The inner diameter of the solenoid CUSP superconducting coil is greater than the outer diameter of a crucible; and the bending radius of the saddle type superconducting coil matches the distance from the center of the crucible to the saddle type superconducting coil.

6. A superconducting magnet coil structure for large-size magnetic- control Czochralski silicon single crystal drawing apparatus according to claim 1, characterized by The central plane of the solenoid CUSP superconducting coil coincides with the central plane of the saddle type superconducting coil.

7. The superconducting magnet coil structure for large-size magnetic- control Czochralski silicon single crystal drawing according to claim 1, characterized in that, ​

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