Crystal growth apparatus and method of using a crystal growth apparatus

Abstract

This invention provides a crystal growth apparatus and a method for using the crystal growth apparatus. The crystal growth apparatus includes a crystal furnace and a lifting unit. The lifting unit can switch between reaching outside the crystal furnace and extending into the crystal furnace. It also includes a hoisting unit, which includes a crucible platform disposed inside the crystal furnace; a hydraulic drive station connected to the hoisting unit for driving the hoisting unit to move up and down; a micro-motion zone is preset inside the crystal furnace. When the lifting unit reaches outside the crystal furnace, the crucible platform can drive the crucible to move up and down within the micro-motion zone, and when the lifting unit extends into the crystal furnace, it can drive the crucible to move up and down in the area below the micro-motion zone.

Description

Technical Field

[0001] This invention relates to the field of crystal preparation technology, and in particular to a crystal growth device and a method of using the crystal growth device based on the crystal growth device. Background Technology

[0002] Crystal growth equipment is an industrial facility that heats raw materials in a crucible to a molten state and prepares crystals using the Czochralski method, the Czochralski method, or a modified Czochralski method. It includes a crystal furnace to house the crucible and a thermal zone within the furnace. The key to successful crystal growth lies in precisely controlling the relative positions of the crucible and the thermal zone to ensure that the molten material within the crucible is in a suitable temperature environment according to the requirements of the crystal preparation process.

[0003] Existing crystal growth equipment mostly uses rigid connections and rigid transmission methods to adjust the height of the crucible within the crystal furnace to regulate the relative position of the crucible and the thermal field. For example, a screw mechanism is used to drive the crucible lifting assembly to move up and down. This connection and transmission method determines that the crucible will gradually rise at a basically fixed rate during the crystal growth process. This makes it impossible for the crucible to flexibly change its height and movement parameters in real time according to the temperature fluctuations of the thermal field, and it is difficult for the molten material inside to be in the most suitable temperature environment for crystal growth. Summary of the Invention

[0004] In view of this, the present invention provides a crystal growth apparatus that can dynamically and rapidly adjust the height position and motion parameters of the crucible in the crystal furnace according to the temperature fluctuation of the thermal field, thereby changing the relative position between the crucible and the thermal field in real time.

[0005] The crystal growth apparatus provided by the present invention includes a crystal furnace and a lifting unit. The lifting unit can switch between reaching outside the crystal furnace and extending into the crystal furnace. It also includes a lifting unit, including a crucible platform disposed inside the crystal furnace; and a hydraulic drive station connected to the lifting unit for driving the lifting unit to move up and down.

[0006] The crystal furnace is pre-set with a micro-motion zone. When the lifting unit reaches the outside of the crystal furnace, the crucible platform can drive the crucible to move up and down in the micro-motion zone, and when the lifting unit extends into the crystal furnace, it can drive the crucible to move up and down in the area below the micro-motion zone.

[0007] Compared with existing technologies, the crystal growth equipment provided by this invention uses hydraulic drive to move the lifting unit relative to the crystal furnace, replacing the existing rigid connection transmission scheme. This allows the crucible to move at varying speeds and directions by allocating different hydraulic driving forces to the hydraulic drive station. For example, it enables the crucible to stop abruptly, start rapidly, return quickly to its original position, reciprocate lifting, and variable-speed lifting within the crystal furnace. Furthermore, based on the real-time temperature gradient distribution and thermal power changes within the crystal furnace, the height and movement parameters of the crucible can be adjusted in real time, preventing the molten material from missing the optimal temperature range for crystal growth, thus improving the quality of the final crystal.

[0008] Furthermore, the crystal growth apparatus of the present invention can also use a hydraulically driven lifting unit to move the crucible within a micro-motion range, allowing the crucible to switch between supporting the crystal rod and detaching from the crystal rod. When the crucible is detached from the crystal rod by a certain distance, the problem of the crucible being scratched by the bottom of the crystal rod due to the shaking of the crystal rod during the seed crystal cutting process can be avoided. This better protects the crucible and prevents contamination of the molten material inside the crucible after damage, thus improving the quality of the subsequently obtained crystal.

[0009] In one embodiment, the lifting unit further includes a lifting shaft, one of which has a centering slot and the other has a centering block fixed thereon, and the centering block and the inner wall of the centering slot form a guide fit along the axial direction of the lifting shaft.

[0010] With this configuration, the lifting shaft and the crucible platform can be precisely connected through a guide fit. After they are connected and fixed, they are set coaxially, which can improve the rotational synchronization of the crucible platform when it follows the lifting shaft and eliminate the adverse effects of coaxiality deviation between the crucible platform and the lifting shaft on the rotational accuracy of the crucible platform.

[0011] In one embodiment, a centering slot is provided at the end of the lifting shaft that is relatively close to the top of the crystal furnace, and a centering block is fixed at the end of the crucible platform that is away from the top of the crystal furnace. The outer wall of the centering block and the inner wall of the centering slot have the same shape, and both are conical surfaces centered on the axis of the lifting shaft; and / or,

[0012] The lifting shaft includes a first shaft and a second shaft that are fixedly connected. The second shaft is fixedly connected to the crucible platform. The second shaft is a graphite shaft, a molybdenum shaft, or a tungsten shaft.

[0013] This design ensures a more stable connection between the lifting shaft and the crucible platform, preventing relative wobbling and allowing for a secure fit between the centering block and the inner wall of the centering slot. The lifting shaft features a split yet fixedly connected structure, with the first shaft receiving the input power and the second shaft exhibiting better heat resistance. This design overcomes the defects of thermal expansion and deformation or decreased mechanical properties of the lifting shaft after being heated by the crucible platform, enabling the crucible to rotate smoothly.

[0014] The present invention also provides a method of using a crystal growth apparatus, wherein the crystal growth apparatus is the crystal growth apparatus of the present invention, and the method includes:

[0015] Adjust the movement state of the lifting unit so that after the lifting unit reaches the outside of the crystal furnace, the crucible is in the micro-motion range inside the crystal furnace;

[0016] The driving lifting unit brings the crucible to the lower limit position of the micro-motion range so that a clearance gap is formed between the crucible and the crystal rod;

[0017] Shear force is applied to the seed crystal with clearance gaps until the seed crystal breaks, and the crystal rod is supported by a crucible.

[0018] The crystal growth apparatus provided by this invention allows for the suspension of the crystal rod relative to the crucible during the seed crystal cutting process. The suspension height of the crystal rod relative to the crucible is the height of the micro-motion zone. This helps protect the crucible from scratches by the crystal rod, especially during the seed crystal cutting process where the crystal rod's movement can cause scratches and cracks inside the crucible. This prevents debris and material components from diffusing into the melt after crucible damage, thus maintaining the purity of the melt and reducing impurities, thereby ensuring the quality of the obtained crystal.

[0019] In one embodiment, a shear force is applied to the seed crystal while a clearance gap is formed until the seed crystal breaks, and the crystal rod is supported by a crucible, including:

[0020] The cutting unit moves relatively close to the seed crystal to shear the seed crystal;

[0021] The cutting unit moves relative to the seed crystal, causing the seed crystal to abut against the cutting unit at the position it was in before being sheared.

[0022] With this configuration, the cutting unit achieves multifunctional integration, which can both apply shearing force to the seed crystal and resist the seed crystal to allow the crystal rod to stop shaking and return to stillness as soon as possible, so that the crucible can support the crystal rod as quickly as possible.

[0023] In one embodiment, a shear force is applied to the seed crystal while a clearance gap is formed until the seed crystal breaks, and the crystal rod is supported by a crucible, including:

[0024] Monitor the shaking of the crystal rod;

[0025] When the crystal rod stops shaking, the cutting unit moves relatively close to the seed crystal to cut the seed crystal, and the same part of the seed crystal is cut multiple times.

[0026] With this setup, the seed crystal can return to its original position after the crystal rod stops shaking, which is the position the seed crystal was in before it was first sheared. Then, applying force to the seed crystal ensures that the force is applied to the same location as the location where the seed crystal was first sheared, thereby accelerating the breakage of the seed crystal.

[0027] In one embodiment, monitoring the wobbling of the crystal rod includes:

[0028] The force sensor is used to contact the lifting unit, and the force of the lifting unit's reaction force on the force sensor is measured.

[0029] If the amplitude of the force signal change measured by the force sensor is less than the preset amplitude range, the shaking of the crystal rod is determined to stop.

[0030] This setup allows for a simpler and more intuitive determination of crystal rod swaying based on the swaying of the lifting unit.

[0031] In one embodiment, the method of using the crystal growth apparatus further includes:

[0032] The lifting unit is driven to lift the crucible and follow the movement of the pulling unit, so that the crystal rod follows the movement of the pulling unit; and

[0033] The driving lifting unit moves the crucible to the lower limit position of the micro-motion range to create a clearance gap between the crucible and the crystal rod, including:

[0034] The lifting unit is driven to descend so that the crucible moves from the upper limit position of the micro-motion range to the lower limit position of the micro-motion range.

[0035] In one embodiment, adjusting the movement state of the lifting unit so that after the lifting unit reaches outside the crystal furnace, the crucible is in the micro-motion range inside the crystal furnace includes:

[0036] Calculate the outward bulge height of the lower redundant section;

[0037] When the pulling unit reaches outside the crystal furnace, the estimated height and the convex height are summed, and the summation result is determined as the distance from the upper limit position of the micro-motion range to the top of the crystal furnace.

[0038] The lower redundant part is located at the end of the crystal rod that is relatively far away from the seed crystal. The outward convex height is the dimension of the lower redundant part in the axial direction of the crystal rod. The estimated height is the sum of the dimensions of the main body of the crystal rod and the seed crystal located in the crystal furnace in the axial direction of the crystal rod.

[0039] This setup makes it easier to determine the exact location of the micro-motion range within the crystal furnace by defining the upper limit position.

[0040] In one embodiment, calculating the outward convex height of the lower redundant portion includes:

[0041] The actual weight of the seed crystal and the crystal rod is measured to obtain the measured weight value;

[0042] The difference between the measured weight value and the estimated weight value is used to obtain the deviation weight value, while the estimated weight value is obtained based on the crystal growth process.

[0043] The volume of the lower redundant part is calculated based on the deviation weight value and the density of the crystal rod.

[0044] The outer diameter of the crystal rod is used as the base diameter of the fitted cone, and the height of the fitted cone is calculated based on the volume of the redundant part at the lower end, which is then used as the convex height. The fitted cone is an imaginary cone with the axis of the crystal rod as the center line and the outer diameter of the crystal rod as the base diameter. Attached Figure Description

[0045] Figure 1 This is a cross-sectional view of a crystal growth apparatus according to an embodiment of the present invention;

[0046] Figure 2 This is a partial structural schematic diagram of a crystal growth apparatus according to an embodiment of the present invention;

[0047] Figure 3 for Figure 2 Axonometric view of the crystal growth equipment shown after it has been cut open;

[0048] Figure 4 This is a partial structural schematic diagram of the truncation unit according to an embodiment of the present invention;

[0049] Figure 5 This is a partial structural schematic diagram of the truncation unit according to an embodiment of the present invention.

[0050] Explanation of reference numerals in the attached figures:

[0051] 10. Crystal furnace; 11. Furnace lid; 111. Lifting opening; 12. Furnace body; 13. Furnace cavity; 14. Crucible; 15. Furnace bottom; 151. Lifting opening; 16. Furnace felt;

[0052] 20. Lifting unit; 21. Upper shaft; 22. Seed crystal connection section;

[0053] 31. Hollow tube; 32. First sealing joint; 33. Second sealing joint; 34. Lifting sealing tube; 35. First connecting piece; 36. Second connecting piece;

[0054] 40. Lifting unit; 41. Lifting cantilever; 42. Crystal drive component; 43. Lifting guide rail;

[0055] 50. Lifting unit; 51. Crucible platform; 511. Centering block; 52. Lifting shaft; 521. Centering slot; 522. First shaft; 523. Second shaft;

[0056] 60. Hydraulic drive unit; 61. Lifting carriage; 62. Column; 63. Lifting guide rail;

[0057] 70. Frame; 80. Pressure locking unit;

[0058] 90. Cut-off unit; 91. Lateral extrusion component; 911. Protruding ridge end; 92. Lateral abutment component; 921. Shearing groove; 922. Abutment receiving groove; 93. Extrusion drive component; 94. Abutment drive component;

[0059] 210. Seed crystal; 220. Crystal rod; 231. Upper redundant part; 232. Lower redundant part. Detailed Implementation

[0060] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0062] This application provides a crystal growth device, which is an industrial facility that can obtain artificial crystals by heating and melting raw materials through processes such as the Czochralski method, the Czochralski method, and the modified Czochralski method. It can be used to manufacture sapphire, silicon single crystals, or other metal compound or non-metal compound crystals. For example, sapphire crystals produced by the crystal growth device can be used as raw materials for the photovoltaic industry or the semiconductor industry.

[0063] Please see Figures 1-2The crystal growth equipment includes a crystal furnace 10, a pulling unit 20, and a lifting unit 40. The crystal furnace 10 houses a crucible 14 and a heating field. The crucible 14 holds the raw materials required for crystal growth, and the heating field heats the crucible 14 to melt the crystal growth materials. The pulling unit 20 extends into the crystal furnace 10 to guide the crystal growth. It then connects to the precipitated seed crystal 210 and moves the seed crystal 210 and crystal rod 220 up and down. After being lifted outside the crystal furnace 10, the seed crystal 210 can be cut by the cutting unit 90, thus separating the seed crystal 210 and crystal rod 220. The lifting unit 40 connects to the pulling unit 20 and applies a driving force to it. The driving force applied to the pulling unit 20 includes a pulling force that moves the pulling unit 20, seed crystal 210, and crystal rod 220 up and down along the axial direction of the pulling unit 20, and a rotational force that rotates the pulling unit 20, seed crystal 210, and crystal rod 220 around the axis of the pulling unit 20.

[0064] The crystal growth equipment also includes a lifting unit 50, which extends into the crystal furnace 10 and carries the crucible 14. After the raw material in the crucible 14 melts, the lifting unit 50 can move up or down to move the crucible 14 up and down within the crystal furnace 10. It is worth noting that the up and down movement of the crucible 14 is not random. It must be ensured that the crucible 14 and the lifting unit 20 move with the same orientation and maintain a basically the same pace and rhythm. That is, the crucible 14 must move up and down synchronously with the lifting unit 20 so that the crystal rod 220 inside the crucible 14 moves with the lifting unit 20. Furthermore, the height of the crucible 14 within the crystal furnace 10 must correspond to the temperature environment required for the crystal growth process, so that the molten material is within the temperature range most suitable for crystal growth.

[0065] The crystal furnace 10 includes a hollow furnace body 12, a furnace bottom 15 and a furnace cover 11 located at both ends of the furnace body 12. The furnace bottom 15 and the furnace cover 11 are sealed to the edges of the openings at both ends of the furnace body 12, and the three together form a furnace cavity 13. A crucible 14 and a heat field are disposed within the furnace cavity 13. In addition, a furnace felt 16 is provided inside the furnace cavity 13 surrounding the crucible 14. The furnace cover 11 has a lifting opening 111 that communicates with the furnace cavity 13, allowing a lifting unit 20 to pass through the outside of the furnace cover 11 and extend into the furnace cavity 13. The furnace bottom 15 has a lifting opening 151 that communicates with the furnace cavity 13, allowing a lifting unit 50 to pass through the outside of the furnace bottom 15 and extend into the furnace cavity 13. To facilitate the installation of the lifting unit 50 and the crystal furnace 10, the crystal growth equipment also includes a frame 70, on which the crystal furnace 10 is supported and suspended relative to the ground.

[0066] The lifting unit 20 includes a fixedly connected upper shaft 21 and a seed crystal connecting section 22. The axis of the upper shaft 21 serves as the axis of the lifting unit 20. The upper shaft 21 is suspended relative to the furnace bottom 15 of the crystal furnace 10. The seed crystal connecting section 22 is fixedly connected to one end of the upper shaft 21 that is relatively close to the furnace bottom 15 of the crystal furnace 10. The lifting unit 20 can switch between extending into the crystal furnace 10 and reaching outside the crystal furnace 10. When the lifting unit 20 extends into the crystal furnace 10 through the lifting opening 111, either at least part of the seed crystal connecting section 22 can extend into the crystal furnace 10, or all of the seed crystal connecting section 22 and part of the upper shaft 21 can extend into the crystal furnace 10. As crystal growth proceeds, the lifting unit 20 is driven upward by the lifting unit 40, gradually reducing its length within the crystal furnace 10 until it reaches outside the furnace 10. At this point, the end of the seed crystal connecting section 22 that is relatively far from the upper shaft 21 is not lower than the outer side of the furnace cover 11 and exits the lifting opening 111. When the lifting unit 20 reaches outside the crystal furnace 10, it means that crystal growth has ended and the crystal rod 220 has taken shape. To facilitate the cutting of the seed crystal 210 by the cutting unit 90, the seed crystal connecting section 22 is preferably higher than the outer side of the furnace cover 11, so that part of the seed crystal 210 can be lifted to the outside of the furnace cover 11.

[0067] The lifting unit 40 includes a lifting cantilever 41 that is suspended relative to the furnace cover 11 of the crystal furnace 10 and can be raised and lowered. It also includes a lifting guide rail 43 that slides with the lifting cantilever 41. The lifting cantilever 41 moves linearly along the lifting guide rail 43, driving the lifting unit 20, seed crystal 210, and crystal rod 220 to translate along a linear trajectory. Optionally, the furnace body 12 has a hollow cylindrical or hollow prismatic structure. The axis of the furnace body 12 is the same as the axis of the crystal furnace 10, extending vertically. The furnace cover 11 and furnace bottom 15 extend horizontally. The axis of the crystal furnace 10 coincides with the axis of the lifting opening 111 and the axis of the lifting opening 151. The portion of the lifting unit 50 extending into the furnace body 12 can horizontally support the crucible 14. Both the lifting unit 20 and the lifting unit 50 can move up and down along the axis of the crystal furnace 10. The lifting guide rail 43 extends vertically and is parallel to the axis of the crystal furnace 10.

[0068] Furthermore, the upper shaft 21 and the seed crystal connecting section 22 can be coaxially and fixedly connected. The lifting unit 40 also includes a crystal rotation drive component 42 installed on the lifting arm 41 and drivenly connected to the upper shaft 21. The crystal rotation drive force can drive the lifting unit 20 to rotate around the axis of the upper shaft 21.

[0069] Furthermore, the crystal growth equipment also includes a hollow tube 31 fitted with the lifting unit 20, and a first sealing joint 32 and a second sealing joint 33 respectively connected to both ends of the hollow tube 31. The first sealing joint 32 is fixedly connected to the lifting cantilever 41 and forms a sealed fit. The second sealing joint 33 is detachably connected to the crystal furnace 10. When the second sealing joint 33 is connected to the crystal furnace 10, a fixed sealed fit is formed between them. At this time, the lifting cantilever 41, the hollow tube 31, the first sealing joint 32, the second sealing joint 33, and the crystal furnace 10 jointly seal and surround the lifting unit 20. After the crystal rod 220 is grown, the second sealing joint 33 is detached from the crystal furnace 10, at which time the seed crystal connecting section 22 and part of the seed crystal 210 can be exposed so that the cutting unit 90 can cut off the seed crystal 210. Optionally, the hollow tube 31 is a corrugated tube with elastic expansion capability, and the second sealing joint 33 is detachably connected to the edge of the lifting opening 111 on the furnace cover 11. The crystal growth equipment also includes a pressure locking unit 80 installed in the crystal furnace 10. The pressure locking unit 80 is capable of abutting the second sealing mating part 33 and applying pressure to it so that the contact pressure between the second sealing mating part 33 and the edge of the lifting opening 111 is sufficient to form a reliable sealing fit.

[0070] The crystal growth apparatus provided by this invention also includes a hydraulic drive station 60, which is connected to a lifting unit 50 and used to hydraulically drive the lifting unit 50 to move up and down. The hydraulic drive station 60 can be located below the frame 70, that is, below the outer side of the furnace bottom 15 of the crystal furnace 10. The lifting unit 50 includes a crucible platform 51 disposed within the crystal furnace 10. The crucible platform 51 has a horizontally extended platform for horizontally supporting the crucible 14. The crucible platform 51 moves up and down within the crystal furnace 10 as driven by the hydraulic drive station 60. In addition, the lifting unit 50 also includes a lifting shaft 52, which is fixed to the crucible platform 51 by a plug-in connection. After plugging in, the two are coaxially connected. The axis of the lifting shaft 52 coincides with the axis of the crystal furnace 10, and the lifting unit 50 can move up and down along the axis of the lifting shaft 52.

[0071] Optionally, the lifting shaft 52 includes a first shaft 522 and a second shaft 523 coaxially fixedly connected. The hydraulic drive station 60 drives and connects to the first shaft 522, and the end of the second shaft 523 that is relatively far away from the first shaft 522 is fixedly inserted into the crucible platform 51. The first shaft 522 can be a steel shaft, and the second shaft 523 can be a graphite shaft, or a molybdenum shaft, tungsten shaft, or other shaft made of heat-resistant material.

[0072] Further, please refer to Figure 3The lifting shaft 52 has a centering slot 521 at the end that is closer to the top of the crystal furnace 10, that is, at the end of the second shaft 523 that is farther away from the first shaft 522. The crucible platform 51 also includes a centering block 511 protruding from the platform on the side opposite to the top of the crystal furnace 10. The inner wall of the centering block 511 and the centering slot 521 have the same shape. Both are conical surfaces centered on the axis of the lifting shaft 52. Thus, the centering block 511 and the centering slot 521 can form a guiding fit along the axis of the lifting shaft 52. Of course, the positions of the centering block 511 and the centering slot 521 can also be interchanged. The crucible platform 51 is always located inside the furnace body 12. When the lifting unit 50 descends to its lowest point, the crucible platform 51 is located at the furnace bottom 15. At this time, the distance between the crucible 14 and the furnace cover 11 reaches its maximum, and the centering block 511 is partially inserted through the lifting opening 151. The end of the centering block 511 that is relatively far from the platform can extend out of the crystal furnace 10.

[0073] Furthermore, the hydraulic drive station 60 includes a hydraulic drive assembly, a column 62 disposed below the bottom of the crystal furnace 10, a lifting guide rail 63 mounted on the column 62 and extending in a straight direction, and a lifting carriage 61 that slides in cooperation with the lifting guide rail 63. The hydraulic drive assembly is connected to the lifting carriage 61 and can distribute hydraulic driving forces of different magnitudes, directions, or durations according to system control commands to drive the lifting carriage 61 to rise, fall, translate, or change the speed of movement along the lifting guide rail 63. The end of the lifting unit 50 that is relatively far from the top of the crystal furnace 10, that is, the end of the first shaft 522 that is relatively far from the crucible platform 51, is connected to the lifting carriage 61. Optionally, the lifting guide rail 63 extends in a vertical direction and is parallel to the axis of the crystal furnace 10.

[0074] Furthermore, the crystal growth equipment also includes a lifting sealing tube 34 that houses the lifting unit 50, and a first docking member 35 and a second docking member 36 respectively connected to both ends of the lifting sealing tube 34. The first docking member 35 is fixedly connected to the outer side of the furnace bottom 15 of the crystal furnace 10 to form a sealed fit. Preferably, the first docking member 35 is fixedly connected to the edge of the lifting opening 151 and forms a sealed fit. The second docking member 36 is fixedly connected to the lifting slide 61 to form a sealed fit. The lifting sealing tube 34 is preferably a corrugated tube capable of expansion and contraction to adapt to changes in the distance between the lifting slide 61 and the furnace bottom 15 of the crystal furnace 10. Thus, the lifting slide 61, the second docking member 36, the lifting sealing tube 34, the first docking member 35, and the crystal furnace 10 seal and surround the lifting unit 50.

[0075] Furthermore, in one embodiment of the present invention, the crystal growth apparatus further includes a cutting unit 90. The cutting unit 90 can be disposed outside the crystal furnace 10 for external cutting of the seed crystal 210, or disposed inside the crystal furnace 10 for internal cutting of the seed crystal 210. The cutting unit 90 includes a lateral extrusion member 91 and a lateral abutment member 92, which are disposed facing each other. It also includes an extrusion drive member 93 that connects to and drives the lateral extrusion member 91 to move closer to the lateral abutment member 92, and an abutment drive member 94 that connects to and drives the lateral abutment member 92 to move closer to the lateral extrusion member 91. The lateral extrusion member 91 is used to extrude the seed crystal 210 to apply shear force to the seed crystal 210, and the lateral abutment member 92 is used to abut against the seed crystal 210 to ensure that the seed crystal 210 does not deviate so that it can be accurately extruded by the lateral extrusion member 91 to form a shear notch. At the same time, the lateral abutment member 92 and the lateral extrusion member 91 form an interlocking fit.

[0076] Optional, please refer to Figures 4-5 The lateral extrusion member 91 has a protruding end 911 for extruding the seed crystal 210 at one end relative to the lateral abutment member 92. The lateral abutment member 92 has a shearing groove 921 at one end relative to the lateral extrusion member 91. The protruding end 911 can be inserted into and fixedly fitted with the shearing groove 921. The edge of the protruding end 911 extends horizontally, and the groove of the shearing groove 921 also extends horizontally. In addition, the lateral abutment member 92 also has a vertically extending abutment receiving groove 922 at one end relative to the lateral extrusion member 91. The abutment receiving groove 922 intersects and communicates with the shearing groove 921 to receive the seed crystal 210. The position where the seed crystal 210 is extruded to form a shearing notch is located in the area formed by the intersection of the abutment receiving groove 922 and the shearing groove 921.

[0077] Taking the external cutting method of seed crystal 210 as an example, after the crystal rod 220 is grown and formed, the lifting arm 41 drives the lifting unit 20 to rise to its highest point. At this time, the lifting unit 20 reaches the outside of the crystal furnace 10. Then, the second sealing docking part 33 is disassembled from the crystal furnace 10. The hollow tube 31 elastically contracts, causing the second sealing docking part 33 to detach from the furnace cover 11 and move closer to the lifting arm 41 to reset, so that the seed crystal connecting section 22 and part of the seed crystal 210 are exposed. At this time, the seed crystal 210 extending out of the furnace cover 11 is located between the lateral extrusion member 91 and the lateral abutment member 92. Then, the lateral extrusion member 91 and the lateral abutment member 92 cooperate to cut off the seed crystal 210.

[0078] It is understood that in other embodiments, the lateral abutment 92 can be replaced with another lateral extrusion member 91, and the two lateral extrusion members 91 can work together to move in opposite directions to extrude the seed crystal 210 until it breaks. Alternatively, only one lateral extrusion member 91 can be provided, and the extrusion drive member 93 can drive it to repeatedly impact the seed crystal 210 to break the seed crystal 210.

[0079] It should be noted that the present invention does not limit the specific form and location of the cutting unit 90. The cutting unit 90 can be a constituent unit in the crystal growth equipment, which can be used to automatically cut the seed crystal 210, or it can be a manual tool independent of the crystal growth equipment, in which personnel manually apply force to the cutting unit 90 to complete the cutting operation of the seed crystal 210.

[0080] Compared to current solutions that use rigid connection transmission methods such as ball screws to drive the lifting assembly to raise and lower the crucible 14, the crystal growth equipment provided by this invention uses a hydraulic drive to drive the lifting assembly. This allows the crucible 14 to perform rapid stops, rapid starts, rapid returns, reciprocating lifting, and variable-rate lifting movements within the crystal furnace 10, according to the needs of the crystal growth process. This enables flexible, precise, and real-time adjustments to the height of the crucible 14 within the crystal furnace 10, based on real-time monitoring of the temperature gradient distribution and thermal power changes. This ensures that the crystal growth material within the crucible 14 is always within the optimal temperature range for crystal ingot 220 growth, allowing the crucible 14 to dynamically track the optimal height position for crystal growth. Ultimately, this significantly improves the quality of the resulting crystal ingot 220.

[0081] More importantly, hydraulically driven lifting unit 50 allows for high-frequency lifting and lowering of both the lifting unit 50 and the crucible 14 within a very small height range. This not only allows for rapid and minute changes in the height of the crucible 14 but also eliminates mechanical wear. In contrast, the transmission precision of commonly used ball screws is inferior to that of hydraulic drives, leading to inaccurate and insensitive responses of the crucible 14 to system control commands. This results in inconsistencies between the displacement of the crucible 14, the displacement of the lifting assembly, and the displacement required by the system commands. Furthermore, the clearance in rigid connection transmission schemes causes sluggish displacement of the crucible 14, preventing it from responding to system control commands in real time and causing the molten material inside the crucible 14 to frequently miss its optimal temperature range. Moreover, high-frequency lifting and lowering within a very small stroke range increases the clearance of the ball screw, exacerbating transmission errors.

[0082] The present invention also provides a method for using a crystal growth apparatus based on the above-mentioned crystal growth equipment, the method comprising the following steps:

[0083] S10, the hydraulically adjusted lifting unit 50 is used to adjust the movement state of the lifting unit 20 so that after the lifting unit 20 reaches the outside of the crystal furnace 10, the crucible 14 is in the micro-motion range inside the crystal furnace 10.

[0084] S20, the hydraulically driven lifting unit 50 brings the crucible 14 to the lower limit position of the micro-motion range so that a clearance gap is formed between the crucible 14 and the crystal rod 220.

[0085] S30. Apply shear force to the seed crystal 210 while the clearance gap is formed until the seed crystal 210 breaks, and use the crucible 14 to support the crystal rod 220.

[0086] Please refer to it again. Figure 4 , Figure 4 The diagram illustrates the structure of the seed crystal 210 and the crystal rod 220 after growth. One end of the crystal rod 220 connected to the seed crystal 210 forms a generally conical or frustum-shaped upper redundant portion 231. The other end of the crystal rod 220, relatively away from the seed crystal 210, also forms a generally conical or frustum-shaped lower redundant portion 232. The crystal rod 220 also includes a crystal rod body located between the upper redundant portion 231 and the lower redundant portion 232, and the crystal rod body is generally cylindrical. After the crystal rod 220 is grown, the crucible 14 supports the crystal rod 220 by supporting the lower redundant portion 232. Since residual molten material remains in the crucible 14 after the crystal rod 220 is grown, at least a portion of the lower redundant portion 232 will be immersed in this molten material.

[0087] The micro-motion range mentioned in the above steps is a height range determined according to the crystal growth process and crystal specifications. This range is located inside the crystal furnace 10 and has an upper limit position relatively close to the furnace cover 11 and a lower limit position relatively close to the furnace bottom 15, which are set vertically. When the crucible 14 is in the upper limit position, the crucible 14 contacts the lower redundant part 232 and carries the crystal rod 220. When the crucible 14 is in the lower limit position, a clearance gap is formed between the crucible 14 and the lower redundant part 232. The width of the clearance gap, that is, the distance of the clearance gap along the axis of the crystal furnace 10, is the span of the micro-motion range in the vertical direction, and is also the stroke of the crucible 14 from the upper limit position to the lower limit position / from the lower limit position to the upper limit position.

[0088] The reason for setting a lower limit position, so that the crucible 14 forms a clearance gap with the lower redundant part 232 when it is in the lower limit position, is that when a shearing force is applied to the seed crystal 210 to cut it off, the crystal rod 220 will wobble relative to the pulling unit 20. This will cause the lower redundant part 232 to slide relative to the crucible 14, or the lower redundant part 232 will tend to rub against the crucible 14. This wobbling or rubbing tendency will cause the lower redundant part 232 to scratch the inner wall of the crucible 14 and form scratches. The material components of the crucible 14 that detach from the scratches will diffuse into the molten material, affecting the subsequent crystal growth and causing impurities to be mixed in the subsequently obtained crystal rod 220, resulting in a decrease in purity. Setting a lower limit position, so that the crucible 14 is separated from the lower redundant part 232 when it is in the lower limit position, can prevent the crystal rod 220 from scratching the crucible 14 due to wobbling.

[0089] The vertical span of the micro-motion zone, i.e., the width of the clearance gap, is determined based on the crystal hardness, crystal density, and shape / volume. In principle, it must ensure that when the crucible 14 is at its lower limit position, the crystal rod 220, after separating from the seed crystal 210, falling into the crucible 14 will not damage it. Since some molten material remains inside the crucible 14 after the crystal rod 220 has grown, this molten material can buffer the impact of the crystal rod 220, thus protecting the crucible 14 from cracks caused by the impact. The height of the micro-motion zone within the crystal furnace 10 can be determined by determining the height of the upper limit position within the crystal furnace 10. The method for determining the height of the upper limit position within the crystal furnace 10 will be explained in detail later.

[0090] Step S10, adjusting the motion state of the lifting unit 50 includes the following situations:

[0091] (i) First, the hydraulic drive station 60 drives the lifting unit 50 to rise along with the lifting unit 20. Then, the hydraulic drive component changes the hydraulic drive force to make the lifting unit 50 decelerate and rise. Finally, before the lifting unit 20 reaches the outside of the crystal furnace 10, the lifting unit 50 stops moving first, and the crucible 14 stays at the lower limit position of the micro-motion range. In this case, the crucible 14 will not reach or pass the upper limit position, and can be selected to stay at the lower limit position until the seed crystal 210 breaks and the seed crystal 210 and the crystal rod 220 are separated.

[0092] (II) First, the lifting unit 50 is driven by the hydraulic drive station 60 to rise along with the lifting unit 20. When the lifting unit 20 reaches outside the crystal furnace 10, the crucible 14 is also moved to the upper limit position of the micro-motion range and pauses briefly. Then, the hydraulic drive assembly changes the direction of the hydraulic drive force, and the lifting unit 50 is driven by the hydraulic drive station 60 to fold back and descend until the crucible 14 reaches the lower limit position of the micro-motion range from the upper limit position. After that, the lifting unit 50 can be kept fixed, so that the crucible 14 continues to stay at the lower limit position until the seed crystal 210 breaks and the seed crystal 210 and the crystal rod 220 are separated. Thus, the method of using the crystal growth equipment also includes:

[0093] S40, the hydraulically driven lifting unit 50 lifts the crucible 14 and moves with the lifting unit 20, so that the crystal rod 220 moves with the lifting unit 20;

[0094] Step S20, namely, the hydraulically driven lifting unit 50 bringing the crucible 14 to the lower limit position of the micro-motion range so as to form a clearance gap between the crucible 14 and the crystal rod 220, includes:

[0095] S21, the hydraulically driven lifting unit 50 moves downward so that the crucible 14 moves from the upper limit position of the micro-motion range to the lower limit position of the micro-motion range.

[0096] This invention does not specifically limit the number of times the seed crystal 210 is subjected to the shearing force of the cutting unit 90. The seed crystal 210 can be broken by multiple short impacts, by multiple compressions, or by a combination of compressions and short impacts. It can even be cut by first compressing or impacting the seed crystal 210, and then cutting along the impact or compression marks. However, it is important to note that each time shearing force is applied to the seed crystal 210, regardless of whether the force is applied by compression, impact, or sawing, it must be done with a clearance gap in place.

[0097] Furthermore, as mentioned above, when a shearing force is applied to the seed crystal 210, the crystal rod 220 will sway relative to the lifting unit 20, causing the seed crystal 210 to sway along with it. This is very disadvantageous in situations where force is repeatedly applied to the seed crystal 210 to break it, because the swaying of the seed crystal 210 will cause the position of the seed crystal 210 under subsequent force to be inconsistent with the position of the seed crystal 210 under initial or first force application, making it difficult for the seed crystal 210 to break quickly. To overcome the adverse effects of the swaying of the crystal rod 220 on the subsequent shearing of the seed crystal 210, step S30, applying a shearing force to the seed crystal 210 with a clearance gap formed until the seed crystal 210 breaks, and using the crucible 14 to support the crystal rod 220, includes:

[0098] S31, drive the cutting unit 90 to move relatively close to the seed crystal 210 to shear the seed crystal 210;

[0099] S32, drive the cutting unit 90 to move relative to the seed crystal 210, so that the seed crystal 210 abuts against the cutting unit 90 at the position it was in before being sheared;

[0100] S33. Monitor the shaking of crystal rod 220;

[0101] S34. When the crystal rod 220 stops shaking, the cutting unit 90 is driven to move relatively close to the seed crystal 210 to cut the seed crystal 210. The position of the seed crystal 210 is the same for multiple cuts.

[0102] The specific execution method of step S31 is not particularly limited. It can either use the lateral extrusion member 91 to apply extrusion force to the seed crystal 210 for several seconds, or use the convex end 911 of the lateral extrusion member 91 to briefly impact the seed crystal 210 for no more than 0.2 seconds.

[0103] Step S32 can be achieved using the lateral extrusion member 91. After applying shear force to the seed crystal 210, the lateral extrusion member 91 moves a certain distance away from the axis of the lifting unit 20. At this point, the lateral extrusion member 91 is in contact with the seed crystal 210, which was stationary before receiving the shear force, and there is no contact pressure between them. As the seed crystal 210 wobbles back to its position before being sheared, it is stopped and limited by the lateral extrusion member 91. After the lateral extrusion member 91 stops and limits the seed crystal 210 multiple times, the wobbling of the seed crystal 210 and the crystal rod 220 tends to stop. Applying shear force to the seed crystal 210 afterwards ensures that the subsequent force application point is consistent with the initial force application point of the seed crystal 210. Alternatively, step S32 can also be achieved using the lateral abutment member 92. Because of the abutment receiving groove 922, the time required for the seed crystal 210 and the crystal rod 220 to stop wobbling is shorter.

[0104] Furthermore, in order to more conveniently and promptly determine the swaying of the crystal rod 220 and to promptly know when the crystal rod 220 returns to a stationary state, step S33 includes:

[0105] S331. Using a force sensor to contact the lifting unit 20, measure the force of the lifting unit 20 acting on the force sensor.

[0106] S332. If the amplitude of the force signal change measured by the force sensor is less than the preset amplitude range, it is determined that the shaking of the crystal rod 220 will stop.

[0107] Using a force sensor to monitor the swaying of the lifting unit 20 not only allows the force sensor to be placed outside the crystal furnace 10, protecting it from the residual heat inside the furnace 12, but also makes the monitoring results easier for personnel to access. Since the swaying of the lifting unit 20 is approximately equivalent to the swaying of the seed crystal 210 and the crystal ingot 220, the determination of crystal swaying is easier. Using the force data received by the force sensor as an indicator of the swaying amplitude of the lifting unit 20 makes the state when the crystal ingot 220 stops swaying closer to its state when it is completely still, resulting in a more reliable judgment. Given that it takes a long time for the seed crystal 210 and the crystal ingot 220 to completely return to stillness, step S332 can shorten the waiting time for the seed crystal 210 and the crystal ingot 220 to stop swaying, as long as the swaying amplitude of the seed crystal 210 and the crystal ingot 220 is within an acceptable range and does not significantly affect the subsequent shearing of the seed crystal 210.

[0108] Furthermore, in order to determine the height of the upper limit position within the crystal furnace 10, and thus determine the position of the micro-motion range within the crystal furnace 10, step S10 includes:

[0109] S11. Calculate the outward convex height of the lower redundant part 232;

[0110] S12. When the lifting unit 20 reaches outside the crystal furnace 10, the estimated height and the convex height are summed, and the summed result is used as the distance from the upper limit position of the micro-motion range to the top of the crystal furnace 10.

[0111] As mentioned above, the lower redundant portion 232 is located at the end of the crystal rod body that is relatively far from the seed crystal 210. The outward protrusion height is the dimension of the lower redundant portion 232 in the direction of the crystal rod 220 axis. The estimated height is the sum of the dimensions of the crystal rod body, the upper redundant portion 231, and the portion of the seed crystal 210 located in the crystal furnace 10 in the direction of the crystal rod 220 axis. In other words, the estimated height can be considered as the dimension of the crystal portion that is still located in the crystal furnace 10 along the direction of the crystal rod 220 axis when the pulling unit 20 reaches outside the crystal furnace 10, excluding the lower redundant portion 232.

[0112] Since the lifting stroke of the lifting unit 20 during its upward movement can be measured, the lengths of the seed crystal 210, the upper redundant part 231, and the crystal rod body along the axial direction of the crystal rod 220 can be determined according to the crystal growth process and crystal preparation requirements. Therefore, when the lifting unit 20 reaches outside the crystal furnace 10, the seed crystal 210 and the crystal rod 220 have both reached their respective highest positions. In other words, at this time, the estimated height along the axial direction of the crystal rod 220 can be obtained and is at its shortest. Therefore, it is only necessary to determine the convex height of the lower redundant part 232, and then sum the estimated height with the convex height to obtain the distance from the crucible 14 to the furnace cover 11 when it is at its upper limit position. Here is a method for calculating the estimated height: Estimated height = Length of seed crystal 210 + Length of crystal rod body + Height of upper redundant part 231 - Lifting stroke of lifting unit 20, where the length refers to the dimension along the axial direction of the crystal rod 220, and the height of the upper redundant part 231 is the dimension of the upper redundant part 231 along the axial direction of the crystal rod 220.

[0113] Further, step S11 includes:

[0114] S111. Measure the actual weight of seed crystal 210 and crystal rod 220 to obtain the measured weight value;

[0115] S112. The difference between the measured weight value and the estimated weight value is used to obtain the deviation weight value. The estimated weight value is obtained according to the crystal growth process and crystal preparation requirements.

[0116] S113. Calculate the volume of the lower redundant part 232 based on the deviation weight value and the density of the crystal rod 220.

[0117] S114. Using the outer diameter of the crystal rod 220 as the base diameter of the fitted cone, calculate the height of the fitted cone based on the volume of the lower redundant part 232, and use it as the outward convex height. The fitted cone is an imaginary cone with the axis of the crystal rod 220 as the center and the outer diameter of the crystal rod 220 as its base diameter.

[0118] Based on current crystal fabrication processes, the final crystal rod 220 will have a roughly conical lower redundant portion 232 at its end furthest from the seed crystal 210. Since the actual lower redundant portion 232 is not a standard cone, its outer wall will have a certain curvature, making it difficult to accurately obtain the actual convex height of the lower redundant portion 232. This invention provides a scheme to obtain an approximate convex height: the shape of the lower redundant portion 232 is assumed to be a standard cone, and the height of this hypothetical cone is used as the theoretical convex height, which is greater than or equal to the actual convex height.

[0119] The actual weight of the seed crystal 210 and the crystal rod 220 can be measured by sensors installed on the lifting unit 20 or the lifting cantilever 41. The density of the seed crystal 210 and the crystal rod 220 can be obtained according to the crystal preparation requirements, and the estimated weight can be obtained according to the crystal growth process and crystal preparation requirements. Specifically, the estimated weight can be regarded as the sum of the weight of the seed crystal 210 and the portion of the crystal rod 220 excluding the lower redundant part 232. Its specific value can be obtained by multiplying the density and the estimated volume. The estimated volume can be calculated based on the size data of the seed crystal 210, the size data of the upper redundant part 231, and the size data of the crystal rod body.

[0120] The difference between the measured weight and the estimated weight is the weight of the lower redundant part 232. Next, the volume of the assumed standard cone can be obtained, and then the height of the assumed standard cone can be calculated. This result is taken as the theoretical convex height. Since the actual shape of the lower redundant part 232 is close to that of a standard cone, it is permissible to approximate the theoretical convex height as the actual convex height of the lower redundant part 232.

[0121] The technical features of the above-described embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0122] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any appropriate changes and variations made to the above embodiments within the essential spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for using a crystal growth apparatus, the crystal growth apparatus comprising a crystal furnace (10), a pulling unit (20), a lifting unit (50) and a driving station, the crystal furnace (10) comprising a furnace bottom (15) and a furnace cover (11), the pulling unit (20) being switchable between reaching outside the crystal furnace (10) and extending into the crystal furnace (10), the lifting unit (50) comprising a crucible table (51) arranged in the crystal furnace (10), the driving station being configured to drive the lifting unit (50) to move up and down; a micro-motion interval being predefined in the crystal furnace (10), the micro-motion interval having an upper limit position and a lower limit position arranged along a vertical direction, the upper limit position being relatively close to the furnace cover (11), and the lower limit position being relatively close to the furnace bottom (15); when the crucible is at the upper limit position, the crucible carries a crystal rod; when the crucible is at the lower limit position, an avoiding gap is formed between the crucible and the crystal rod, the avoiding gap having a width equal to a span of the micro-motion interval along the vertical direction; the method comprising: adjusting a movement state of the lifting unit (50) such that, after the pulling unit (20) reaches outside the crystal furnace (10), the crucible (14) is located in the micro-motion interval in the crystal furnace (10); driving the lifting unit (50) to bring the crucible (14) to the lower limit position of the micro-motion interval, so as to form the avoiding gap between the crucible (14) and the crystal rod (220); applying a shearing force to a seed crystal (210) in a state where the avoiding gap is formed, until the seed crystal (210) is broken, and using the crucible (14) to carry the crystal rod (220). The method for applying a shearing force to a seed crystal (210) in a state where the avoiding gap is formed, until the seed crystal (210) is broken, and using the crucible (14) to carry the crystal rod (220) comprises: moving a cutting-off unit (90) relatively close to the seed crystal (210) to shear the seed crystal (210); moving the cutting-off unit (90) relative to the seed crystal (210) such that the seed crystal (210) abuts against the cutting-off unit (90) at a position where the seed crystal (210) is before being sheared. The method for applying a shearing force to a seed crystal (210) in a state where the avoiding gap is formed, until the seed crystal (210) is broken, and using the crucible (14) to carry the crystal rod (220) comprises: monitoring a wobble of the crystal rod (220); in a case where the wobble of the crystal rod (220) stops, moving the cutting-off unit (90) relatively close to the seed crystal (210) to shear the seed crystal (210). The method for monitoring a wobble of the crystal rod (220) comprises: contacting the pulling unit (20) with a force sensor to measure a force of the pulling unit (20) acting on the force sensor; in a case where a variation amplitude of a force signal measured by the force sensor is smaller than a preset amplitude range, determining that the wobble of the crystal rod (220) stops. The method for using the crystal growth apparatus further comprises: ​ ​ ​ 2. The method of using a crystal growing apparatus of claim 1, wherein, ​ ​ ​ 3. The method of using a crystal growing apparatus of claim 2, wherein, ​ ​ ​ 4. The method of using a crystal growing apparatus of claim 3, wherein, ​ ​ ​ 5. The method of using a crystal growing apparatus of claim 1, wherein, ​ The lifting unit (50) is driven to lift the crucible (14) and move along with the pulling unit (20) so that the crystal bar (220) moves along with the pulling unit (20); and The lifting unit (50) is driven to bring the crucible (14) to the lower limit position of the micro-motion range so that the crucible (14) forms a clearance with the crystal bar (220), comprising: The lifting unit (50) is driven to move downward so that the crucible (14) reaches the lower limit position of the micro-motion range from the upper limit position of the micro-motion range.

6. The method of using a crystal growing apparatus of claim 1, wherein, The movement state of the lifting unit (50) is adjusted so that, after the pulling unit (20) reaches outside the crystal furnace (10), the crucible (14) is in the micro-motion range in the crystal furnace (10), comprising: The outer protruding height of the lower end redundant part (232) is calculated; In the case that the pulling unit (20) reaches outside the crystal furnace (10), the estimated height and the outer protruding height are summed up, and the obtained sum is determined as the distance from the upper limit position of the micro-motion range to the top of the crystal furnace (10); The lower end redundant part (232) is located at an end of the crystal bar (220) far away from the seed crystal (210), the outer protruding height is the size of the lower end redundant part (232) in the axial direction of the crystal bar (220), and the estimated height is the sum of the size of the body part of the crystal bar (220) and the size of the seed crystal (210) in the axial direction of the crystal bar (220) in the crystal furnace (10).

7. The method of using a crystal growing apparatus of claim 6, wherein, The outer protruding height of the lower end redundant part (232) is calculated, comprising: The actual weight of the seed crystal (210) and the crystal bar (220) is measured to obtain an actual weight value; The actual weight value and an estimated weight value are subtracted to obtain a deviation weight value, and the estimated weight value is obtained according to a crystal growth process; According to the deviation weight value and the density of the crystal bar (220), the volume of the lower end redundant part (232) is calculated; The outer diameter size of the crystal bar (220) is taken as the base diameter of a fitting conical body, the height of the fitting conical body is calculated according to the volume of the lower end redundant part (232), and the height is taken as the outer protruding height; the fitting conical body is a conical body with the axis of the crystal bar as the center line and with the outer diameter of the crystal bar as the base diameter.

Images