A magnetic field switching system for a superconducting magnet for large-size magnetic control Czochralski silicon single crystal

Abstract

The application discloses a magnetic field switching system of a superconducting magnet for large-size magnetic control Czochralski monocrystalline silicon, and relates to the technical field of superconducting magnet magnetic control Czochralski monocrystalline silicon, comprising a magnetic shielding vacuum cavity, a solenoid CUSP superconducting coil, a saddle type superconducting coil, a first high-temperature superconducting current lead, a second high-temperature superconducting current lead, a copper terminal current lead, a first superconducting switch, a second superconducting switch, a third superconducting switch, a fourth superconducting switch, a superconducting power supply and a programmable controller. The application constructs the circuit connection structure of the superconducting switch and the superconducting magnet coil on the basis of combining the solenoid CUSP superconducting coil and the saddle type superconducting coil to construct the composite superconducting magnet coil structure, guarantees the flexibility of multi-magnetic field switching, strengthens the system reliability, and adapts to the demand of magnetic field dynamic regulation and control for 300mm / 450mm silicon wafer preparation.

Description

TECHNICAL FIELD

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

[0002] For the preparation of large-size silicon wafers, especially 300mm silicon wafers and next-generation 450mm silicon wafers, the traditional single-current magnetic field control has bottlenecks in crystal quality. At present, the superconducting magnet for magnetic control Czochraski silicon single crystal has horizontal field, CUSP hook-shaped field and the like, which can obviously reduce the influence of melt thermal convection on single crystal quality when arranged on a single crystal furnace, so more and more magnetic control Czochraski single crystal equipment is configured with a superconducting magnet for magnetic control Czochraski single crystal. A single superconducting magnet can only meet one fixed magnetic field type and cannot switch the magnetic field type. Moreover, a single magnet can only be used with one single crystal furnace; for the production of large-size (for example, 450mm in diameter) single crystal silicon rods, different types of superconducting magnets may need to be applied to achieve this, which makes the wafer factory need to be equipped with different types of superconducting magnets and single crystal furnaces to meet the needs of different requirements of single crystal silicon rods. However, a single superconducting magnet and a single crystal furnace are expensive, which greatly increases the production investment. Therefore, it is necessary to study the magnetic field switching system of a superconducting magnet for large-size magnetic control Czochraski silicon single crystal.

[0003] In the prior art, Chinese patent CN117995505A discloses a switchable field shape magnetic control crystal pulling superconducting magnet, comprising: a superconducting magnet body and a rotating mechanism; the rotating mechanism is used for supporting the superconducting magnet body and allowing the superconducting magnet body to rotate in a normal vertical plane; the superconducting magnet body comprises: a magnetic shielding vacuum cavity, a cold shield, a first superconducting coil, a second superconducting coil, a pull rod, a refrigerator, a current lead and a superconducting power supply; the first superconducting coil and the second superconducting coil are two oppositely distributed annular coils, which are arranged inside the cold shield; the superconducting power supply is switchably connected with the first superconducting coil and the second superconducting coil through the current lead, so that the first superconducting coil and the second superconducting coil are connected in series or in reverse series.

[0004] However, the above prior art realizes the switching of vertical field, horizontal field and CUSP hook-shaped field by adjusting the magnet mechanical station and the electrical connection mode, and the multi-magnetic field switching flexibility and system reliability are poor, which is difficult to adapt to the demand of 300mm / 450mm silicon wafer preparation for magnetic field dynamic regulation. SUMMARY

[0005] The present application provides a magnetic field switching system of a superconducting magnet for large-size magnetic control Czochraski silicon single crystal, to solve the problem of poor multi-magnetic field switching flexibility and system reliability of the existing superconducting magnet magnetic control Czochraski single crystal technology, which is difficult to adapt to the demand of 300mm / 450mm silicon wafer preparation for magnetic field dynamic regulation.

[0006] In one aspect, the application provides a magnetic field switching system of a superconducting magnet for large-size magnetic control Czochralski silicon single crystal, comprising: a magnetic shielding vacuum chamber, a solenoid CUSP superconducting coil, a saddle-shaped superconducting coil, a first high-temperature superconducting current lead, a second high-temperature superconducting current lead, a copper terminal current lead, a first superconducting switch, a second superconducting switch, a third superconducting switch, a fourth superconducting switch, a superconducting power supply, and a programmable controller.

[0007] The magnetic shielding vacuum chamber 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 above and below, and are fixedly arranged inside the magnetic shielding vacuum chamber.

[0009] The saddle-shaped superconducting coil comprises a saddle-shaped first superconducting coil and a saddle-shaped second superconducting coil, which are two saddle-shaped 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] One end of the first high-temperature superconducting current lead is connected to the first superconducting switch and the third superconducting switch, respectively, and the outgoing line of the solenoid CUSP first superconducting coil is connected through the first superconducting switch, and the outgoing line of the saddle-shaped first superconducting coil is connected through the third superconducting switch; the other end of the first high-temperature superconducting current lead is connected to the positive electrode of the copper terminal current lead.

[0011] One end of the second high-temperature superconducting current lead is connected to the outgoing line of the solenoid CUSP second superconducting coil and the incoming line of the saddle-shaped second superconducting coil, respectively; the other end of the second high-temperature superconducting current lead is connected to the negative electrode of the copper terminal current lead.

[0012] The two ends of the second superconducting switch are respectively connected to the outgoing line of the solenoid CUSP first superconducting coil and the outgoing line of the solenoid CUSP second superconducting coil.

[0013] The two ends of the fourth superconducting switch are respectively connected to the outgoing line of the saddle-shaped first superconducting coil and the incoming line of the saddle-shaped second superconducting coil.

[0014] The superconducting power supply is connected to the positive electrode and the negative electrode of the copper terminal current lead, respectively.

[0015] The programmable controller is in communication connection and / or electrical connection with the superconducting power supply.

[0016] In a possible implementation, the wire-in of the solenoid CUSP first superconducting coil is connected with the wire-out of the solenoid CUSP second superconducting coil, that is, the solenoid CUSP first superconducting coil and the solenoid CUSP second superconducting coil are electrically connected in positive series.

[0017] The wire-in of the saddle first superconducting coil is connected with the wire-out of the saddle second superconducting coil, that is, the saddle first superconducting coil and the saddle second superconducting coil are electrically connected in positive series.

[0018] In a possible implementation, the first high-temperature superconducting current lead and the second high-temperature superconducting current lead are both insulated and installed on the top of the magnetic shielding vacuum cavity.

[0019] In a possible implementation, the programmable controller is communicatively and / or electrically connected with a monitor.

[0020] 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 insulation layer.

[0021] 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.

[0022] In a possible implementation, the first superconducting switch is provided with a first superconducting switch heater.

[0023] The second superconducting switch is provided with a second superconducting switch heater.

[0024] The third superconducting switch is provided with a third superconducting switch heater.

[0025] The fourth superconducting switch is provided with a fourth superconducting switch heater.

[0026] In a possible implementation, each superconducting switch heater is located in an inner layer of the corresponding superconducting switch, and an outer layer is sequentially formed by a polyimide film and a NbTi superconducting wire layer.

[0027] In a possible implementation, the magnetic field switching system of the superconducting magnet for large-size magnetic control Czochralski silicon further includes a refrigerator and a cold-copper plate.

[0028] The refrigerator is fixedly arranged on the top of the magnetic shielding vacuum cavity, a secondary cold head of the refrigerator is connected with the cold-copper plate, and the cold-copper plate is connected with the solenoid CUSP superconducting coil and the saddle superconducting coil through a soft connection copper belt.

[0029] The first superconducting switch, the second superconducting switch, the third superconducting switch and the fourth superconducting switch are fixedly arranged on the cold-copper plate.

[0030] The magnetic field switching system of the superconducting magnet for large-size magnetic control Czochralski silicon has the following advantages:

[0031] By constructing the circuit connection structure of the superconducting switch and the superconducting magnet coil on the basis of constructing the composite superconducting magnet coil structure by combining the CUSP superconducting coil and the saddle-shaped superconducting coil, the system reliability is strengthened while the flexibility of multi-magnetic field switching is ensured, and the demand of the preparation of 300mm / 450mm silicon wafer for the dynamic regulation and control of the magnetic field is adapted.

[0032] By cooperation of the four superconducting switches and the two kinds of superconducting coils, the smooth switching operation of the CUSP hook-shaped field, the horizontal field and the mixed field can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0034] Figure 1 A circuit connection schematic diagram of the magnetic field switching system of the superconducting magnet for large-size magnetic control Czochralski silicon is provided for the embodiments of the present application.

[0035] Figure 2 A coil structure schematic diagram of the magnetic field switching system of the superconducting magnet for large-size magnetic control Czochralski silicon is provided for the embodiments of the present application.

[0036] Figure 3 A superconducting switch layout schematic diagram located at the secondary cold head of the refrigerator is provided for the embodiments of the present application.

[0037] Figure 4 A CUSP hook-shaped field schematic diagram of the magnetic field switching system of the superconducting magnet for large-size magnetic control Czochralski silicon is provided for the embodiments of the present application.

[0038] Figure 5 A horizontal field schematic diagram of the magnetic field switching system of the superconducting magnet for large-size magnetic control Czochralski silicon is provided for the embodiments of the present application.

[0039] Figure 6 A mixed field schematic diagram of the magnetic field switching system of the superconducting magnet for large-size magnetic control Czochralski silicon is provided for the embodiments of the present application.

[0040] Reference signs:

[0041] 101 - magnetic shielded vacuum chamber, 1021 - solenoid CUSP first superconducting coil, 1022 - solenoid CUSP second superconducting coil, 1031 - saddle first superconducting coil, 1032 - saddle second superconducting coil, 1041 - first high temperature superconducting current lead, 1042 - second high temperature superconducting current lead, 1051 - copper terminal current lead positive, 1052 - copper terminal current lead negative, 106 - refrigerator, 107 - cold conducting copper plate, 2011 - first superconducting switch, 2012 - second superconducting switch, 2021 - third superconducting switch, 2022 - fourth superconducting switch, 20111 - first superconducting switch heater, 20121 - second superconducting switch heater, 20211 - third superconducting switch heater, 20221 - fourth superconducting switch heater, 301 - superconducting power supply, 302 - programmable controller, 303 - monitor. DETAILED DESCRIPTION

[0042] 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.

[0043] As shown in the drawings, Figures 1 to 3 The present application provides a magnetic field switching system of a superconducting magnet for large-size magnetic control Czochralski silicon, which comprises: a magnetic shielded vacuum chamber 101, a solenoid CUSP superconducting coil, a saddle superconducting coil, a first high temperature superconducting current lead 1041, a second high temperature superconducting current lead 1042, a copper terminal current lead, a first superconducting switch 2011, a second superconducting switch 2012, a third superconducting switch 2021, a fourth superconducting switch 2022, a superconducting power supply 301, and a programmable controller 302.

[0044] The magnetic shielded vacuum chamber 101 is a concentric cylinder.

[0045] 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 shielded vacuum chamber 101.

[0046] 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 the saddle-shaped superconducting coil is fixedly arranged inside the magnetic shielding vacuum cavity 101 and located between the solenoid CUSP first superconducting coil 1021 and the solenoid CUSP second superconducting coil 1022.

[0047] One end of the first high-temperature superconducting current lead 1041 is connected to the first superconducting switch 2011 and the third superconducting switch 2021 respectively, and the outgoing line of the solenoid CUSP first superconducting coil 1021 is connected through the first superconducting switch 2011, and the outgoing line of the saddle-shaped first superconducting coil 1031 is connected through the third superconducting switch 2021; the other end of the first high-temperature superconducting current lead 1041 is connected to the copper terminal current lead positive 1051.

[0048] One end of the second high-temperature superconducting current lead 1042 is connected to the outgoing line of the solenoid CUSP second superconducting coil 1022 and the incoming line of the saddle-shaped second superconducting coil 1032 respectively; the other end of the second high-temperature superconducting current lead 1042 is connected to the copper terminal current lead negative 1052.

[0049] The two ends of the second superconducting switch 2012 are respectively connected to the outgoing line of the solenoid CUSP first superconducting coil 1021 and the outgoing line of the solenoid CUSP second superconducting coil 1022.

[0050] The two ends of the fourth superconducting switch 2022 are respectively connected to the outgoing line of the saddle-shaped first superconducting coil 1031 and the incoming line of the saddle-shaped second superconducting coil 1032.

[0051] The superconducting power supply 301 is connected to the copper terminal current lead positive 1051 and the copper terminal current lead negative 1052 respectively.

[0052] The programmable controller 302 is in communication connection and / or electrical connection with the superconducting power supply 301.

[0053] Specifically, through the above-mentioned circuit connection structure, a closed loop is formed by the superconducting power supply 301 to ensure stable transmission of current.

[0054] Specifically, in the present embodiment, the inside of the magnetic shielding vacuum cavity 101 is a vacuum sealed environment, and the outer wall is a magnetic conductive material to reduce external leakage magnetic field.

[0055] The solenoid CUSP first superconducting coil 1021 and the solenoid CUSP second superconducting coil 1022 are wound on the coil support cylinder; the saddle type first superconducting coil 1031 and the saddle type second superconducting coil 1032 are mechanically fixed on the support frame. Existing superconducting coil fixing technology is adopted, and no more details are given here.

[0056] In the embodiment, the programmable controller 302 is in communication connection with the superconducting power supply 301. The superconducting power supply 301 is a high-precision direct-current superconducting power supply, with an output current range of 0-200A, an output voltage of 0-20V, a stability of not more than 10ppm / h, and a fast current rising and falling capability (rate 0-10A / s adjustable), which provides excitation current for all working coils.

[0057] Exemplarily, the incoming line of the solenoid CUSP first superconducting coil 1021 is connected with the incoming line of the solenoid CUSP second superconducting coil 1022, i.e., the solenoid CUSP first superconducting coil 1021 and the solenoid CUSP second superconducting coil 1022 are electrically reversely connected in series.

[0058] The incoming line of the solenoid CUSP first superconducting coil 1021 is connected with the outgoing line of the solenoid CUSP second superconducting coil 1022, i.e., the solenoid CUSP first superconducting coil 1021 and the solenoid CUSP second superconducting coil 1022 are electrically reversely connected in series.

[0059] Specifically, in the embodiment, the solenoid CUSP first superconducting coil 1021 and the solenoid CUSP second superconducting coil 1022 have equal number of turns and symmetrical geometric parameters; the saddle type first superconducting coil 1031 and the saddle type second superconducting coil 1032 are respectively located on the left and right sides of the refrigerator 106, and the saddle type first superconducting coil 1031 and the saddle type second superconducting coil 1032 have equal number of turns and symmetrical geometric parameters.

[0060] Exemplarily, the first high-temperature superconducting current lead 1041 and the second high-temperature superconducting current lead 1042 are both insulated and installed on the top of the magnetic shielding vacuum cavity 101.

[0061] Exemplarily, the programmable controller 302 is in communication connection and / or electrical connection with the monitor 303.

[0062] Specifically, in the embodiment, the monitor 303 is in communication connection with the programmable controller 302. In other possible embodiments, the monitor 303 can be replaced by a single crystal furnace host computer.

[0063] Exemplarily, the solenoid CUSP superconducting coil is wound with NbTi superconducting wire, and the NbTi superconducting wire is coated with a polyimide insulating layer.

[0064] Exemplarily, the winding structure of the solenoid CUSP superconducting coil is layered and densely wound, and glass cloth is used for insulation between layers, and epoxy resin is used for curing.

[0065] Specifically, in the present embodiment, the central plane of the solenoid CUSP superconducting coil (i.e. the plane where the crucible solid-liquid interface is located) coincides with the central plane of the saddle-shaped superconducting coil, ensuring the uniformity of the transverse magnetic field in the key area.

[0066] In the present embodiment, the two ends of the solenoid CUSP superconducting coil are connected to the axial support column through the annular flange, 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.

[0067] Exemplarily, the first superconducting switch 2011 is provided with a first superconducting switch heater 20111.

[0068] The second superconducting switch 2012 is provided with a second superconducting switch heater 20121.

[0069] The third superconducting switch 2021 is provided with a third superconducting switch heater 20211.

[0070] The fourth superconducting switch 2022 is provided with a fourth superconducting switch heater 20221.

[0071] Specifically, in the present embodiment, the four superconducting switch heaters draw the connecting wires from the superconducting magnet to four different heating power sources of the control system through electrical interfaces, and the heating power sources are controlled by the output of the programmable controller 302. When the programmable controller 302 outputs an electrical signal to the first superconducting switch heater 20111, the first superconducting switch 2011 changes from a superconducting state to a non-superconducting state, at which time the first superconducting switch 2011 no longer has a zero resistance effect, but becomes a resistor and no longer flows current, and the loop current flows to the loop with lower resistance. The second superconducting switch 2012, the third superconducting switch 2021, and the fourth superconducting switch 2022 are the same.

[0072] Exemplarily, each superconducting switch heater is located in the inner layer of the corresponding superconducting switch, and the outer layer is polyimide film and niobium-titanium superconducting wire layer in turn.

[0073] Specifically, in the embodiment, the framework of each superconducting switch is made of T2 copper with good thermal conductivity, glass cloth is used for insulation on the framework roll, the inner layer is a heating layer (i.e. superconducting switch heater) wound by constantan wire, and the outer layer is polyimide film, niobium-titanium superconducting wire layer, the total number of niobium-titanium superconducting wire layers is even, the number of turns of odd layers and even layers is equal, jumper posts are left at the end of the framework, and the niobium-titanium superconducting wire is back-folded and wound at the jumper posts after the completion of the odd layers to form the even layers, so that the niobium-titanium superconducting wire of the superconducting switch is wound into a non-inductive coil. The niobium-titanium superconducting wire is polyimide-coated superconducting wire, has good mechanical properties, high toughness, and is not prone to insulation layer damage, and has an electrical insulation performance greater than 1000V.

[0074] Exemplarily, the magnetic field switching system of the superconducting magnet for large-size magnetic control Czochralski silicon further comprises a refrigerator 106 and a cold-copper plate 107.

[0075] The refrigerator 106 is fixedly arranged at the top of the magnetic shielding vacuum cavity 101, a secondary cold head of the refrigerator 106 is connected to the cold-copper plate 107, and the cold-copper plate 107 is connected to the solenoid CUSP superconducting coil and the saddle-shaped superconducting coil through a soft connection copper belt.

[0076] The first superconducting switch 2011, the second superconducting switch 2012, the third superconducting switch 2021 and the fourth superconducting switch 2022 are fixedly arranged on the cold-copper plate 107.

[0077] Specifically, in the embodiment, two refrigerators 106 are arranged, and the temperature of the cold-copper plate 107 cooled by the secondary cold head of the refrigerator 106 is lower than 4K, wherein the first superconducting switch 2011 and the second superconducting switch 2012 are close to the secondary cold head of one refrigerator 106, and the third superconducting switch 2021 and the fourth superconducting switch 2022 are close to the secondary cold head of the other refrigerator 106.

[0078] In a possible embodiment, the switching process of the magnetic field switching system of the superconducting magnet for large-size magnetic control Czochralski silicon provided by the application is as follows:

[0079] For the single crystal furnace crucible area of 300mm / 450mm and the single crystal silicon rod, the synthesized magnetic field uniform area composed of the solenoid CUSP superconducting coil and the saddle-shaped superconducting coil completely covers the melt and the crystal growth interface in the crucible. At this time, the superconducting magnet is in a low-temperature superconducting state. A magnetic field can be generated by electric current. The control system (monitor 303 or single crystal furnace upper computer) sends a switching instruction according to the demand of the single crystal silicon rod growth stage.

[0080] During the operation of the single crystal furnace, according to the growth stage (seed pulling, shoulder placing, equal diameter) of the single crystal silicon rod, the seed pulling and shoulder placing stage is dominated by horizontal field, and the magnetic field distribution is as shown inFigure 5 As shown, that is, the saddle type superconducting coil generates rated magnetic field, solenoid CUSP superconducting coil does not generate magnetic field, the magnetic field is mainly the transverse component, inhibiting melt convection, reducing initial defects; the equal diameter stage is the growth stage of the single crystal silicon rod, which needs to meet multiple requirements in cooperation, that is, both the saddle type superconducting coil and the solenoid CUSP superconducting coil need to generate magnetic field, and the magnetic field distribution is as shown in Figure 6 As shown, balancing oxygen content and dislocation density, ensuring the uniformity of the single crystal silicon melt pool. In this magnetic field transformation process, the monitor 303 or the single crystal furnace upper computer gives the magnetic field instruction to the programmable controller 302, and the programmable controller 302 gives the instruction to the superconducting power supply 301 to output current, so as to provide working current for the required superconducting coil to generate the required magnetic field.

[0081] Before the seeding stage, the programmable controller 302 controls the superconducting switch heater, so that the first superconducting switch 2011 and the fourth superconducting switch 2022 are in the resistance state, and the third superconducting switch 2021 and the second superconducting switch 2012 are in the superconducting state. That is, the first superconducting switch heater 20111 and the fourth superconducting switch heater 20221 receive an electrical signal to start heating, and the third superconducting switch heater 20211 and the second superconducting switch heater 20121 do not receive an electrical signal and do not heat. According to the current command of the magnetic field response of the superconducting power supply 301 given by the programmable controller 302, the positive output current of the superconducting power supply 301 passes through the first high-temperature superconducting current lead 1041, then passes through the third superconducting switch 2021, and the current continues to flow through the saddle-shaped superconducting coil, returns to the negative electrode of the superconducting power supply 301 through the second high-temperature superconducting current lead 1042, and forms a current loop. At this time, the saddle-shaped superconducting coil generates a horizontal field through the current. After reaching the required magnetic field of the crystal growth process, the single crystal furnace starts to seed. When the seeding shoulder stage ends, the diameter-keeping stage begins. According to the requirement of the crystal growth process, the strength of the horizontal field is adjusted by adjusting the current of the saddle-shaped superconducting coil. After adjusting the strength of the horizontal field to the required horizontal field of the diameter-keeping stage, the programmable controller 302 gives an instruction to close the power switch of the fourth superconducting switch heater 20221, and the fourth superconducting switch heater 20221 stops working. The fourth superconducting switch 2022 returns to the superconducting state. In this way, the current required in the diameter-keeping stage forms a closed loop between the saddle-shaped superconducting coil and the fourth superconducting switch 2022. Then the superconducting power supply 301 withdraws the current to zero. The programmable controller 302 gives an instruction to open the power switch of the third superconducting switch heater 20211, and the third superconducting switch heater 20211 starts working. The third superconducting switch 2021 is in the resistance state. Then the programmable controller 302 gives an instruction to close the power of the first superconducting switch heater 20111, and the first superconducting switch 2011 is in the superconducting state. The programmable controller 302 gives an instruction to open the power of the second superconducting switch heater 20121, and the second superconducting switch 2012 is in the resistance state. At this time, the first superconducting switch 2011 and the fourth superconducting switch 2022 are in the superconducting state, and the third superconducting switch 2021 and the second superconducting switch 2012 are in the resistance state. According to the current command of the magnetic field response of the superconducting power supply 301 given by the programmable controller 302, the positive output current of the superconducting power supply 301 passes through the first high-temperature superconducting current lead 1041, then passes through the first superconducting switch 2011, and the current continues to flow through the CUSP solenoid superconducting coil, returns to the negative electrode of the superconducting power supply 301 through the second high-temperature superconducting current lead 1042, and forms a current loop. At this time, the CUSP solenoid superconducting coil generates a CUSP hook-shaped field through the rated current. In this way, the composite magnetic field of the diameter-keeping state is generated, which meets the requirement of the diameter-keeping. Further, the programmable controller 302 gives an instruction to close the second superconducting switch heater 20121, and the second superconducting switch 2012 returns to the superconducting state.The current required by such an equiaxial stage forms a closed loop between the solenoid CUSP superconducting coil and the second superconducting switch 2012. Then the superconducting power supply 301 is de-energized to zero current, and the superconducting magnet works in a closed loop operating state. When the single crystal silicon rod equiaxial growth is completed, the magnetic field of the solenoid CUSP superconducting coil is first exited, and then the magnetic field of the saddle-shaped superconducting coil is exited, and the exiting steps are just the opposite of the previous operation. In this way, the crystal pulling of a large-size silicon rod is completed.

[0082] In addition, the magnetic field switching system of the large-size magnetic control Czochralski single crystal silicon superconducting magnet of the present application can also realize the CUSP hook-shaped field or the horizontal field alone. When the CUSP hook-shaped field is realized alone by giving an instruction to the programmable controller 302 through the monitor 303 or the single crystal furnace upper computer, before the seeding shoulder growth stage, the programmable controller 302 controls the superconducting switch heater, so that the third superconducting switch 2021 and the second superconducting switch 2012 are in a resistive state, and the first superconducting switch 2011 and the fourth superconducting switch 2022 are in a superconducting state. According to the requirements of the crystal pulling process, the programmable controller 302 gives the superconducting power supply 301 a current instruction of the magnetic field, and the positive output current of the superconducting power supply 301 flows through the first high-temperature superconducting current lead 1041, then to the first superconducting switch 2011, and then continues to flow through the solenoid CUSP superconducting coil, and returns to the negative of the superconducting power supply 301 through the second high-temperature superconducting current lead 1042, forming a current loop, which is kept stable when the working current is reached, and the superconducting magnet realizes the CUSP hook-shaped field distribution. At this time, the saddle-shaped superconducting coil does not generate a magnetic field. The magnetic field configuration is as shown in Figure 4 Of course, the magnetic field can be operated in a closed loop, or can be operated in an open loop with the power supply.

[0083] When the horizontal field is realized alone by giving an instruction to the programmable controller 302 through the monitor 303 or the single crystal furnace upper computer, before the seeding shoulder growth stage, the programmable controller 302 controls the superconducting switch heater, so that the first superconducting switch 2011 and the fourth superconducting switch 2022 are in a resistive state, and the third superconducting switch 2021 and the second superconducting switch 2012 are in a superconducting state. According to the requirements of the crystal pulling process, the programmable controller 302 gives the superconducting power supply 301 a current instruction of the magnetic field, and the positive output current of the superconducting power supply 301 flows through the first high-temperature superconducting current lead 1041, then to the third superconducting switch 2021, and then continues to flow through the saddle-shaped superconducting coil, and returns to the negative of the superconducting power supply 301 through the second high-temperature superconducting current lead 1042, forming a current loop, which is kept stable when the working current is reached, and the superconducting magnet realizes the horizontal field distribution. At this time, the solenoid CUSP superconducting coil does not generate a magnetic field. The magnetic field configuration is as shown in Figure 5 Of course, the magnetic field can be operated in a closed loop, or can be operated in an open loop with the power supply.

[0084] The embodiment of the application constructs the circuit connection structure of the superconducting switch and the superconducting magnet coil on the basis of combining the solenoid CUSP superconducting coil and the saddle type superconducting coil to construct a composite superconducting magnet coil structure, thereby ensuring the flexibility of multi-magnetic field switching, strengthening the system reliability, and adapting to the demand of the magnetic field dynamic regulation for the preparation of 300mm / 450mm silicon wafers.

[0085] Through the cooperation of the four superconducting switches and the two superconducting coils, the smooth switching operation of the CUSP hook-shaped field, the horizontal field and the mixed field can be realized.

[0086] Although the preferred embodiments of the application have been described, those skilled in the art who, once aware of the basic inventive concept, can make further changes and modifications to these embodiments. 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 application.

[0087] Obviously, those skilled in the art can make various modifications and variations to the application without departing from the spirit and scope of the application. Thus, if these modifications and variations of the application fall within the scope of the claims of the application and their equivalent technologies, the application also intends to include these modifications and variations.

Claims

1. A magnetic field switching system for a superconducting magnet for large-size magnetically controlled Czochralski silicon single crystals, characterized in that The device comprises a magnetic shielding vacuum chamber, a solenoid CUSP superconducting coil, a saddle-shaped superconducting coil, a first high-temperature superconducting current lead, a second high-temperature superconducting current lead, a copper terminal current lead, a first superconducting switch, a second superconducting switch, a third superconducting switch, a fourth superconducting switch, a 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, which are two annular solenoid CUSP coils symmetrically distributed above and below, and are fixedly arranged inside the magnetic shielding vacuum chamber. The saddle-shaped superconducting coil comprises a saddle-shaped first superconducting coil and a saddle-shaped second superconducting coil, which are two horse-saddle 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. One end of the first high-temperature superconducting current lead is connected to the first superconducting switch and the third superconducting switch, respectively, and the first superconducting switch is connected to the outgoing line of the solenoid CUSP first superconducting coil, and the third superconducting switch is connected to the outgoing line of the saddle-shaped first superconducting coil; the other end of the first high-temperature superconducting current lead is connected to the positive electrode of the copper terminal current lead. One end of the second high-temperature superconducting current lead is connected to the outgoing line of the solenoid CUSP second superconducting coil and the incoming line of the saddle-shaped second superconducting coil, respectively; the other end of the second high-temperature superconducting current lead is connected to the negative electrode of the copper terminal current lead. The two ends of the second superconducting switch are connected to the outgoing line of the solenoid CUSP first superconducting coil and the outgoing line of the solenoid CUSP second superconducting coil, respectively. The two ends of the fourth superconducting switch are connected to the outgoing line of the saddle-shaped first superconducting coil and the incoming line of the saddle-shaped second superconducting coil, respectively. The incoming line of the solenoid CUSP first superconducting coil is connected to the incoming line of the solenoid CUSP second superconducting coil, i.e., the solenoid CUSP first superconducting coil and the solenoid CUSP second superconducting coil are reversely connected in series. The incoming line of the saddle-shaped first superconducting coil is connected to the outgoing line of the saddle-shaped second superconducting coil, i.e., the saddle-shaped first superconducting coil and the saddle-shaped second superconducting coil are connected in series in positive direction. The superconducting power supply is connected to the positive electrode and the negative electrode of the copper terminal current lead, respectively. The programmable controller is in communication connection and / or electrical connection with the superconducting power supply. The first superconducting switch is provided with a first superconducting switch heater. The second superconducting switch is provided with a second superconducting switch heater. The third superconducting switch is provided with a third superconducting switch heater. The fourth superconducting switch is provided with a fourth superconducting switch heater. The device further comprises a refrigerator and a cold-conducting copper plate. The refrigerator is fixedly arranged on the top of the magnetic shielding vacuum chamber, the secondary cold head of the refrigerator is connected to the cold-conducting copper plate, and the cold-conducting copper plate is connected to the solenoid CUSP superconducting coil and the saddle-shaped superconducting coil through a soft connection copper belt. ​ The first superconducting switch, the second superconducting switch, the third superconducting switch and the fourth superconducting switch are fixedly arranged on the cold lead copper plate.

2. The magnetic field switching system for a superconducting magnet for large-size magnetic -control Czochralski silicon single crystals according to claim 1, characterized in that The first high-temperature superconducting current lead and the second high-temperature superconducting current lead are insulatively arranged on the top of the magnetic shielding vacuum cavity.

3. The magnetic field switching system of a superconducting magnet for a large-size magnetic -control Czochralski silicon single crystal according to claim 1, characterized by The programmable controller is communicatively and / or electrically connected with a monitor.

4. The magnetic field switching system of a superconducting magnet 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.

5. The magnetic field switching system of a superconducting magnet 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 cloth insulation is used between layers, and epoxy resin is used for curing.

Images