Remelting control method and equipment for crystal bar, crystal pulling furnace and medium

Abstract

The invention provides a remelting control method and device for a crystal bar, a crystal pulling furnace and a medium. The remelting control method comprises the following steps: S1, in the process of remelting the shoulder part of a crystal bar in a silicon melt in a quartz crucible, melting the bottom part of the shoulder part until the surface on which the shoulder part is positioned is convex.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor manufacturing technology, and in particular to a method and device for controlling the melting back of a crystal rod, a crystal pulling furnace, and a medium. Background Art

[0002] The Czochralski method (CZ method for short) is a widely used method for producing crystal rods. It involves placing polysilicon raw materials in a quartz crucible of a crystal pulling furnace and heating and melting them to form a silicon melt. Subsequently, the seed crystal is immersed in the silicon melt to guide the silicon melt to grow along the seed crystal. By precisely controlling the process steps of seeding, shoulder placement, shoulder rotation, equal diameter, and finishing, a crystal rod product is finally pulled. However, during the pulling process of the crystal rod, changes in environmental factors or improper operation may cause the crystal rod to break (also known as "broken edge").

[0003] At present, during the process of pulling a crystal rod, if the crystal rod is broken, the pulled part of the crystal rod is usually extended into a quartz crucible for melting back several times until the pulled part is completely melted and then the crystal rod is re-pulled. In contrast to the process of pulling a crystal rod, the melting back process of a crystal rod starts from the tail of the crystal rod and gradually melts back to the shoulder of the crystal rod. During the melting back process, the shoulder of the crystal rod is more prone to silicon melt sputtering (hereinafter referred to as "silicon sputtering"), which will not only interfere with the subsequent crystal rod pulling process, but may also cause damage to the crystal pulling furnace.

[0004] Based on this, there is an urgent need to provide a method for controlling the melting back of a crystal rod that can reduce silicon sputtering. Summary of the invention

[0005] The present disclosure provides a method and equipment for controlling the melting back of a crystal rod, a crystal pulling furnace and a medium; the melting back process of the crystal rod can be automatically controlled, and the problem of silicon splashing easily occurring at the shoulder of the crystal rod during the melting back process in the related art can be solved.

[0006] The technical solution of the present disclosure is achieved as follows: In a first aspect, the present disclosure provides a method for controlling the melting back of a crystal rod, the method comprising step S1: during the melting back of the shoulder of the crystal rod in the silicon melt in a quartz crucible, the bottom of the shoulder is melted so that the surface on which the shoulder is located is convex.

[0007] In some possible implementations, the distance between the highest point and the lowest point of the surface where the bottom of the shoulder is located in the axial direction of the crystal rod is in a range of 10 mm to 30 mm.

[0008] In some possible implementations, the remelting control method further includes step S2: controlling the remaining portion of the shoulder to move downward to remelt the remaining portion in the silicon melt, and repeating steps S1 and S2 until the shoulder is remelted.

[0009] In some possible implementations, during the process of melting back the shoulder of the crystal rod in the silicon melt in the quartz crucible, the bottom of the shoulder is melted so that the surface on which the shoulder is located is convex, including: During the remelting of the shoulder in the silicon melt, the first time length of the shoulder portion in the silicon melt is controlled to be within a range of 2 minutes to 10 minutes, so that the bottom of the shoulder is melted into a convex surface.

[0010] In some possible implementations, during the process of melting back the shoulder of the crystal rod in the silicon melt in the quartz crucible, before the bottom of the shoulder is melted so that the surface on which the shoulder is located is convex, the melting back control method further includes: When the equal-diameter section of the crystal rod is melted back to a point where the distance difference between the bottom of the equal-diameter section and the bottom of the shoulder is a set first distance, the quartz crucible is controlled to descend so that the distance between the liquid level of the silicon melt in the quartz crucible and the guide tube is a set second distance.

[0011] In some possible implementations, the second distance is in the range of 40 mm to 80 mm.

[0012] In some possible implementations, during the process of melting back the shoulder of the crystal rod in the silicon melt in the quartz crucible, before the bottom of the shoulder is melted so that the surface on which the shoulder is located is convex, the melting back control method further includes: When the equal-diameter section of the crystal rod is melted back so that the distance difference between the bottom of the equal-diameter section and the bottom of the shoulder is the first distance, controlling the rotation speed of the crystal rod to be within a range of 2 rpm to 5 rpm; Controlling the rotation speed of the quartz crucible to be within the range of 1 rev / min to 3 rev / min; and The magnetic induction intensity of the horizontal magnetic field is controlled to be in the range of 800Gs to 2000Gs.

[0013] In some possible implementations, corresponding to each drop of the shoulder, the magnetic induction intensity of the horizontal magnetic field increases by 100 Gs to 500 Gs, until the magnetic induction intensity of the horizontal magnetic field is in the range of 2000 Gs to 3000 Gs.

[0014] In some possible implementations, during the process of melting back the shoulder of the crystal rod in the silicon melt in the quartz crucible, before the bottom of the shoulder is melted so that the surface on which the shoulder is located is convex, the melting back control method further includes: When the equal-diameter section of the crystal rod is melted back to a point where the distance difference between the bottom of the equal-diameter section and the bottom of the shoulder is a set third distance, the inert gas is controlled to purge the furnace and continue to purge for a second time period; wherein the third distance is smaller than the first distance.

[0015] In some possible implementations, the flow rate of the inert gas when purging the furnace is in a range of 120 slpm to 150 slpm, and the second time period is in a range of 2 min to 5 min.

[0016] In some possible implementations, after the inert gas stops purging the furnace, the remelting control method further includes: When the crystal rod is controlled to descend until the bottom of the shoulder contacts the liquid surface of the silicon melt, the bottom heater is controlled to be turned off; and The temperature in the furnace corresponding to the process of melting back the shoulder is controlled to be 50° C. to 150° C. higher than the temperature in the furnace corresponding to the process of seeding the crystal rod.

[0017] In some possible implementations, the temperature in the furnace corresponding to the process of melting back the shoulder is controlled to be in the range of 1500° C. to 1700° C.

[0018] In a second aspect, the present disclosure provides a remelting control device for a crystal rod, the remelting control device for a crystal rod comprises a remelting control part; wherein, The remelting control part is configured to melt the bottom of the shoulder into a convex shape when the shoulder of the crystal rod is remelted in the silicon melt in the quartz crucible.

[0019] In a third aspect, the present disclosure provides a melt-back control device for a crystal rod, the melt-back control device for a crystal rod comprising: a processor and a memory; the processor is used to execute instructions stored in the memory to implement the melt-back control method for a crystal rod according to the first aspect.

[0020] In a fourth aspect, the present disclosure provides a crystal pulling furnace, comprising: a crystal rod pulling device, a crucible lifting device, and a remelting control device for the crystal rod according to the second aspect or the third aspect.

[0021] In a fifth aspect, the present disclosure provides a computer storage medium, wherein at least one instruction is stored in the computer storage medium, and when the at least one instruction is executed, the method for controlling the melting back of the crystal rod according to the first aspect is implemented.

[0022] The present disclosure provides a method and equipment for controlling the melting back of a crystal rod, a crystal pulling furnace and a medium. During the melting back of the shoulder of the crystal rod in a silicon melt in a quartz crucible, the bottom of the shoulder is melted into a convex surface, thereby avoiding the occurrence of silicon splashing during the melting back of the shoulder. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a crystal pulling furnace in the related technology.

[0024] Figure 2 Schematic diagram of the shoulder of the crystal rod breaking during the remelting process.

[0025] Figure 3 A flow chart of a method for controlling the melting back of a crystal rod provided in an embodiment of the present disclosure.

[0026] Figure 4 A schematic diagram showing that the bottom of the shoulder of the crystal rod provided in an embodiment of the present disclosure is melted and becomes convex.

[0027] Figure 5 A flow chart of another method for controlling the melting back of a crystal rod provided in an embodiment of the present disclosure.

[0028] Figure 6 A flow chart of another method for controlling the melting back of a crystal rod provided in an embodiment of the present disclosure.

[0029] Figure 7 A flow chart of another method for controlling the melting back of a crystal rod provided in an embodiment of the present disclosure.

[0030] Figure 8 A schematic diagram of the distance difference between the bottom of the equal-diameter section and the bottom of the shoulder of the crystal rod provided in an embodiment of the present disclosure.

[0031] Fig. 9 A schematic diagram of the composition of a remelting control device for a crystal rod provided in an embodiment of the present disclosure.

[0032] Fig.10 A structural block diagram of a remelting control device for a crystal rod provided in an embodiment of the present disclosure.

[0033] Fig.11 A schematic structural diagram of a crystal pulling furnace provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0034] The technical solutions in the present disclosure will be described clearly and completely below in conjunction with the accompanying drawings in the present disclosure.

[0035] It should be noted that, for the sake of clarity, not all features of a specific implementation are described and illustrated in the specification and drawings, and in order to avoid unnecessary details that obscure the technical solution that the present disclosure focuses on, only the device structures and parts that are closely related to the technical solution of the present disclosure are described and illustrated in the specification and drawings, while other details that are not closely related to the technical content of the present disclosure and are known to those skilled in the art are omitted.

[0036] Unless otherwise defined, the technical terms used in the present disclosure should be understood as the common meanings known to those of ordinary skill in the art to which the present disclosure belongs. The terms "first", "second", etc. in the present disclosure do not indicate any order, but are only used for distinction.

[0037] See also Figure 1 , which shows a crystal pulling furnace 1 in the related art. The crystal pulling furnace 1 mainly includes the following components.

[0038] The furnace body 10 is provided with a cavity 101 therein.

[0039] The quartz crucible 20 is disposed at the bottom of the cavity 101 inside the furnace body 10 and is used to contain solid polycrystalline silicon raw materials (or “polycrystalline silicon melt”) in the initial stage of pulling the crystal rod S.

[0040] The graphite crucible 30 is wrapped around the outer periphery of the quartz crucible 20 and is used to provide support for the quartz crucible 20 during the process of heating the polycrystalline silicon raw material.

[0041] The main heater 40 is distributed around the quartz crucible 20 .

[0042] A bottom heater 50, which is disposed between the bottom of the graphite crucible 30 and the bottom of the furnace body 10; The guide tube 60 is disposed above the quartz crucible 20. On the one hand, the guide tube 60 is mainly used to isolate the heat radiation of the main heater 40 and the bottom heater 50 to the crystal rod S, to ensure the temperature gradient required for the growth of the crystal rod S, and further to ensure the crystallization rate of the crystal rod S; on the other hand, the guide tube 60 is used to guide the inert gas such as argon from top to bottom to the top of the silicon melt in the quartz crucible 20 to accelerate the gas flow rate on the liquid surface, thereby accelerating the transportation of volatile impurities.

[0043] In a specific implementation process, after a set mass of polysilicon raw materials are placed in the quartz crucible 20 , the polysilicon raw materials in the quartz crucible 20 are heated and melted by the main heater 40 and the bottom heater 50 to form a silicon melt.

[0044] Of course, the crystal pulling furnace 1 also includes a seed crystal cable 70, a crystal rod pulling device 80 and a crucible lifting device 90. The seed crystal cable 70 is arranged above the quartz crucible 20, and is used to control the seed crystal cable 70 to drop the seed crystal to the solid-liquid interface of the silicon melt and start the processes of seeding, necking, shouldering, equal diameter growth and tailing after the polycrystalline silicon raw material in the quartz crucible 20 is melted to form a silicon melt and the temperature of the solid-liquid interface is stabilized, and finally pull a crystal rod S of a certain length. The crucible lifting device 90 is arranged at the bottom of the graphite crucible 30, and is used to drive the lifting and rotation of the quartz crucible 20 during the process of pulling the crystal rod S.

[0045] As mentioned above, in the process of pulling the crystal rod S using the crystal pulling furnace 1, when a wire breakage or the like occurs, the part of the pulled crystal rod needs to be melted back. However, when melting back to the shoulder S10 of the crystal rod S, the probability of silicon splashing is high. This is because the shoulder of the crystal rod is the part where the diameter gradually increases from the seed crystal, and the rapid change in diameter and the influence of the temperature gradient easily cause the shoulder to generate a large thermal stress during the melting back process. Once the thermal stress exceeds the strength limit of the silicon material, silicon splashing may occur. In addition, when melting back to the shoulder, the size of the crystal rod is significantly reduced and the shape becomes more irregular, which leads to uneven temperature gradient in this case. If the local temperature is too high or the temperature fluctuates greatly, the surface tension of the silicon melt will decrease, thereby increasing the risk of silicon splashing. In addition, the instability of the flow of silicon melt is also one of the important factors leading to the occurrence of silicon splashing. This is mainly caused by factors such as the presence of bubbles, impurities or excessive temperature gradient differences in the silicon melt in the silicon melt in the quartz crucible 20. Finally, the shape and position of the shoulder can also cause silicon splashing. When melting back to the shoulder, the ingot becomes thinner, resulting in lower strength. Figure 2 The shoulder S10 shown is more likely to break, causing silicon melt to sputter out from the break of the shoulder, as shown in FIG. Figure 2 As shown by the dotted arrow in .

[0046] It is understandable that when silicon splashing occurs, the silicon melt may splash onto the components above the quartz crucible 20, causing the silicon melt to cool rapidly and form solid silicon droplets. The longer silicon droplets among these silicon droplets will come into contact with the silicon melt in the quartz crucible 20 during the equal-diameter growth stage of the re-pulling of the crystal rod S, causing the liquid surface of the silicon melt to crystallize, thereby seriously affecting the pulling of the crystal rod S. Moreover, these silicon droplets may fall during the process of re-pulling the crystal rod S due to the gas flow in the furnace and other factors, thereby further increasing the probability of the crystal rod breaking. Finally, the silicon melt splashed onto the various components in the furnace may cause damage to the various components in the furnace, such as the main heater 40, the guide tube 60, etc., to affect the production cycle and increase production costs.

[0047] Based on this, the present disclosure provides a method for controlling the melting back of a crystal rod to reduce the problem of silicon splashing easily occurring at the shoulder of the crystal rod during the melting back process. Figure 3 As shown, the remelting control method specifically includes step S1.

[0048] In step S1 , during the process of melting back the shoulder of the crystal rod in the silicon melt in the quartz crucible 20 , the bottom of the shoulder S10 is melted so that the surface thereof is convex.

[0049] Specifically, if Figure 4 As shown, the convex shape of the surface where the bottom of the shoulder S10 is located means that the surface where the bottom of the shoulder S10 is located faces the silicon melt and presents a convex shape. In this case, the risk of the shoulder S10 breaking due to the concentration of thermal stress can be reduced by changing the distribution of thermal stress on the shoulder S10 during the remelting process, and the strength of the shoulder S10 can be enhanced, thereby reducing the possibility of silicon splashing.

[0050] It should be noted that in Figure 3 In the process, the preceding step before step S1 may include a process of regulating the temperature field in the furnace before the shoulder S10 is melted back; and the subsequent step after step S1 may include a process of continuing to melt back the remaining part of the shoulder S10 after the part of the shoulder S10 in the silicon melt is melted back.

[0051] for Figure 3 In the technical solution shown, in some possible implementations, the distance Δd1 between the highest point and the lowest point of the surface where the bottom of the shoulder S10 is located in the axial direction of the crystal rod S is in the range of 10 mm to 30 mm.

[0052] In the present disclosure, by limiting the range of the distance Δd1 between the highest point and the lowest point of the surface where the bottom of the shoulder S10 is located in the axial direction of the crystal rod S, the shape of the shoulder S10 during the remelting process can be accurately controlled to ensure that the surface where the bottom of the shoulder S10 is located forms a convex shape, thereby improving the remelting quality and avoiding silicon splashing.

[0053] for Figure 3 In some possible implementations of the technical solution shown, Figure 5 As shown, the remelting control method further includes step S2: controlling the remaining portion of the shoulder S10 to move downward to remelt the remaining portion in the silicon melt, and repeating steps S1 and S2 until the remelting of the shoulder S10 is completed.

[0054] During the remelting process of the shoulder S10 of the crystal rod S, the shoulder S10 needs to be extended into the silicon melt in the quartz crucible 20 for multiple times for remelting treatment. Therefore, in the present disclosure, after the bottom of the remaining portion of the shoulder S10 is melted in the silicon melt, the remaining portion is continuously controlled to move downward in the axial direction to remelt the portion of the remaining portion in the silicon melt.

[0055] It can be understood that in the present disclosure, step S1 and step S2 are repeatedly performed until the shoulder S10 of the crystal rod S is melted back, that is, the melting back of the crystal rod S is completed.

[0056] It can be understood that in the present disclosure, the shoulder S10 of the crystal rod S is subjected to multiple remelting methods to ensure that the melting of the shoulder S10 is more uniform. In the specific implementation process, by accurately controlling the descending distance and speed of the shoulder S10 to control the number of remelting of the shoulder S10, the remelting depth and remelting rate of the shoulder S10 can be effectively controlled, thereby ensuring the stability of the remelting process. In addition, multiple remelting of the shoulder S10 is also conducive to eliminating the stress concentration area that may exist in the shoulder S10, further improving the quality and reliability of the remelting.

[0057] In some examples, the descending distance of the shoulder S10 each time may be 5 mm to 20 mm, which may be determined according to actual conditions.

[0058] for Figure 3 According to the technical solution shown, in some possible embodiments, during the process of melting back the shoulder S10 in the silicon melt, the first time length of the portion of the shoulder S10 in the silicon melt is controlled to be within the range of 2 minutes to 10 minutes, so that the bottom of the shoulder S10 is melted into a convex surface.

[0059] It can be understood that in this case, the contact time between the shoulder S10 in the silicon melt and the silicon melt can be ensured during each remelting process, so that the shoulder S10 in the silicon melt can be fully melted, which helps the bottom of the shoulder S10 to be melted into a convex shape.

[0060] for Figure 3 In some possible implementations of the technical solution shown, Figure 6 As shown, during the process of the shoulder S10 of the crystal rod S being melted back in the silicon melt in the quartz crucible 20, before the bottom of the shoulder S10 is melted into a convex surface, the melt back control method also includes step S3: when the equal-diameter section S20 of the crystal rod S is melted back so that the distance difference between the bottom of the equal-diameter section S20 and the bottom of the shoulder S10 is a set first distance, the quartz crucible 20 is controlled to descend so that the distance between the liquid level of the silicon melt in the quartz crucible 20 and the guide tube 60 is a set second distance.

[0061] In some examples, the first distance is set in the range of 15 mm to 40 mm. This is because when the equal diameter section S20 is melted back to a distance difference of 15 mm to 40 mm between its bottom and the bottom of the shoulder S10, the quartz crucible 20 is controlled to descend to increase the distance between the liquid surface of the silicon melt in the quartz crucible 20 and the guide tube 60 to control the heat field distribution in the furnace, so as to reduce the local overheating or temperature unevenness during the melting process, thereby reducing the risk of flow instability of the silicon melt due to temperature unevenness and reducing the risk of silicon splashing. In some examples, the second distance is in the range of 40 mm to 80 mm.

[0062] for Figure 3 In some possible implementations of the technical solution shown, during the process of melting back the shoulder S10 of the crystal rod S in the silicon melt in the quartz crucible 20, before the bottom of the shoulder S10 is melted into a convex surface, the melting back control method further includes: When the equal diameter section S20 of the crystal rod S is melted back to a point where the distance difference between the bottom of the equal diameter section S20 and the bottom of the shoulder S10 is the first distance, the rotation speed of the crystal rod S is controlled within a range of 2 rpm to 5 rpm. Controlling the rotation speed of the quartz crucible 20 to be within a range of 1 rpm to 3 rpm; and The magnetic induction intensity of the horizontal magnetic field is controlled to be in the range of 800Gs to 2000Gs.

[0063] In the present disclosure, by controlling the rotation speed of the crystal rod S to 2 rpm to 5 rpm, the smooth progress of the melting process can be ensured, and the drastic fluctuation of the temperature gradient of the silicon melt caused by the rapid change of the rotation speed of the crystal rod S can be reduced, thereby effectively avoiding the occurrence of silicon splashing.

[0064] In addition, reducing the rotation speed of the quartz crucible 20 during the remelting process can accurately control the flow and temperature gradient distribution of the silicon melt in the quartz crucible 20, thereby optimizing the remelting quality of the crystal ingot S.

[0065] It should be noted that, in the present disclosure, the mechanical center of the horizontal magnetic field is 0mm to 30mm higher than the liquid level of the silicon melt during the equal-diameter growth process when pulling the crystal rod S. Usually, in the specific implementation process, the horizontal magnetic field is arranged on the outside of the main furnace chamber of the crystal pulling furnace 1. It can be understood that the magnetic induction intensity of the horizontal magnetic field can significantly affect the convection intensity of the silicon melt in the quartz crucible 20. Therefore, in the present disclosure, by adjusting the magnetic induction intensity of the horizontal magnetic field, the convection of the silicon melt can be effectively reduced, which helps to maintain the stability and uniformity of the silicon melt during the remelting process, reduce the uneven heat distribution and temperature gradient differences caused by convection, and thus reduce the occurrence of silicon splashing.

[0066] In some examples, corresponding to each decrease of the shoulder S10 , the magnetic induction intensity of the horizontal magnetic field increases by 100 Gs to 500 Gs, until the magnetic induction intensity of the horizontal magnetic field is in the range of 2000 Gs to 3000 Gs.

[0067] Since the diameter of the shoulder S10 of the crystal rod S gradually decreases during the remelting process, the change in the temperature gradient of the silicon melt has a more significant impact on its remelting process, increasing the risk of silicon splashing. In order to solve this technical problem, with each descent of the shoulder S10, the flow state of the silicon melt is regulated by increasing the intensity of the horizontal magnetic field, reducing the change in the temperature gradient, thereby reducing the probability of silicon splashing and promoting uniform remelting of the shoulder S10.

[0068] for Figure 3 In some possible implementations of the technical solution shown, Figure 7 As shown, during the process of the shoulder S10 of the crystal rod S being melted back in the silicon melt in the quartz crucible 20, before the bottom of the shoulder S10 is melted into a convex surface, the melt-back control method also includes step S4: when the equal-diameter section S20 of the crystal rod S is melted back so that the distance difference between the bottom of the equal-diameter section S20 and the bottom of the shoulder S10 is a set third distance, controlling the inert gas to purge the furnace and continue to purge for a second time period; wherein the third distance is smaller than the first distance.

[0069] As mentioned above, silicon splashing is likely to occur when the shoulder S10 of the crystal rod S is melted back. Figure 8 As shown, in the present disclosure, when the equal-diameter section S20 is melted back to a distance difference Δd2 between its bottom and the bottom of the shoulder S10 that is a set third distance, controlling the inert gas to purge the furnace can firstly effectively reduce the surface tension of the liquid surface of the silicon melt and reduce the occurrence of silicon splashing. Secondly, the purge of the inert gas helps to reduce bubbles, impurities, etc. in the silicon melt in the quartz crucible 20, further reducing the possibility of silicon splashing. Finally, by continuously purging the furnace with inert gas, the uniformity of the thermal field in the furnace can be improved, and the phenomenon of excessively high local temperatures or large temperature fluctuations can be reduced, thereby reducing the risk of unstable flow of the silicon melt due to uneven temperature and improving the silicon splashing phenomenon.

[0070] In some examples, the inert gas is argon.

[0071] It should be noted that the third distance is within the range of 5 mm to 15 mm. In the present disclosure, by defining the third distance, it is helpful to timely purge the furnace with inert gas before the shoulder S10 starts to melt back, so that the thermal field distribution in the furnace can be more accurately controlled to ensure good heat exchange between the shoulder S10 and the silicon melt at the initial stage of the melting back of the shoulder S10, thereby more effectively controlling the distribution of thermal stress, preventing the shoulder S10 from cracking, and reducing the possibility of silicon splashing.

[0072] For the above embodiments, in some examples, the flow rate of the inert gas during purging of the furnace is in a range of 120 standard liters per minute (slpm) to 150 slpm, and the second time period is in a range of 2 min to 5 min.

[0073] By limiting the purge flow rate and purge duration of the inert gas, the bubbles and impurities in the silicon melt can be purged in time with the inert gas, and the surface tension of the silicon melt can be controlled in time before the shoulder S10 meltback begins, further avoiding the occurrence of silicon splashing.

[0074] for Figure 3 In some possible implementations of the technical solution shown, after the inert gas stops purging the furnace, the remelting control method further includes: When the crystal rod S is controlled to descend to the bottom of the shoulder S10 and to contact the liquid surface of the silicon melt in the quartz crucible 20, the bottom heater 50 is controlled to be turned off; and The temperature in the furnace corresponding to the process of melting back the shoulder portion S10 is controlled to rise to 50° C. to 150° C. higher than the temperature in the furnace corresponding to the process of seeding the crystal ingot S.

[0075] It is understandable that during the remelting process, if the heating rate is too fast, it may cause uneven melting of the bottom of the shoulder S10 in the silicon melt, thereby causing the strength of the shoulder S10 to become lower, which may also cause the shoulder S10 to crack and trigger the sputtering of the silicon melt. Therefore, in the specific implementation process, the bottom heater 50 is turned off to reduce the heating rate.

[0076] In addition to the aforementioned situations, during the remelting process of the shoulder S10, the temperature in the furnace has an important influence on the remelting process. On the one hand, by controlling the temperature in the furnace during the remelting process, the remelting speed of the shoulder S10 can be ensured, ensuring its smooth remelting and improving the remelting efficiency. On the other hand, by controlling the temperature in the furnace during the remelting process, it can help to improve the uniformity of the temperature gradient distribution of the silicon melt and reduce the convection caused by the temperature gradient difference, thereby obtaining a more uniformly flowing melt and avoiding silicon splashing. In some examples, the furnace temperature corresponding to the remelting shoulder S10 process is controlled to be in the range of 1500°C to 1700°C.

[0077] See Table 1, which shows the data comparison of Examples 1 to 4 and Comparative Examples 1 to 4. Among them, Examples 1 to 4 are crystal rods of different sizes that are melted back at the shoulders of the crystal rods using the technical solution of the present disclosure, and Comparative Examples 1 to 4 are crystal rods of different sizes that are melted back at the shoulders of the crystal rods without using the technical solution provided by the present disclosure. It can be seen from Table 1 that in Examples 1 to 4, the number of silicon splashing phenomena when the shoulder S10 is melted back is greatly reduced, and the average yield is improved.

[0078] It should be noted that the average yield of each of the above embodiments refers to the yield of the crystal rod re-pulled after silicon splashing occurs during the process of melting back the shoulder in the embodiment.

[0079]

[0080] Table 1 Based on the same inventive concept as the above technical solution, see Fig. 9 , which shows a remelting control device 100 for a crystal rod provided by the present disclosure, the remelting control device 100 for a crystal rod comprises: a remelting control unit 110; wherein, The remelting control unit 110 is configured to melt the bottom of the shoulder S10 into a convex shape when the shoulder S10 of the crystal rod S is remelted in the silicon melt in the quartz crucible 20 .

[0081] It should be noted that for the specific implementation methods or implementation examples of the functions configured by the above-mentioned components, please refer to the corresponding steps, implementation methods and examples of the aforementioned technical solutions, and this disclosure will not elaborate on them here.

[0082] It can be understood that in this embodiment, the "part" can be a part of the circuit, a part of the processor, a part of the program or software, etc., and of course it can also be a unit, a module, or a non-modular one.

[0083] In addition, each component in this embodiment may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit may be implemented in the form of hardware or in the form of software function modules.

[0084] If the integrated unit is implemented in the form of a software function module and is not sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this embodiment is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to perform all or part of the steps of the method described in this embodiment.

[0085] Therefore, an embodiment of the present disclosure provides a computer-readable storage medium, which stores at least one instruction. When the at least one instruction is executed, the method for controlling the melting back of a crystal rod according to the aforementioned technical solution is implemented.

[0086] See also Fig.10 , which shows a structural block diagram of a remelting control device 100 for a crystal rod provided by an exemplary embodiment of the present disclosure. In some examples, the remelting control device 100 for a crystal rod can be at least one of a smart phone, a smart watch, a desktop computer, a laptop, a virtual reality terminal, an augmented reality terminal, a wireless terminal, and a laptop portable computer. The remelting control device 100 for a crystal rod has a communication function and can be connected to a wired network or a wireless network. The remelting control device 100 for a crystal rod can generally refer to one of a plurality of terminals, and those skilled in the art can know that the number of the above terminals can be more or less. It can be understood that the remelting control device 100 for a crystal rod undertakes the calculation and processing work of the technical solution of the present disclosure, and the present disclosure does not limit this.

[0087] like Fig.10 As shown, the remelting control device 100 for a crystal ingot in the present disclosure may include one or more of the following components: a processor 130 and a memory 140. The processor 130 is used to execute instructions stored in the memory 140 to implement the remelting control method for a crystal ingot according to the above technical solution.

[0088] Optionally, the processor 130 uses various interfaces and lines to connect various parts of the entire computing device, and executes various functions of the computing device and processes data by running or executing instructions, programs, code sets or instruction sets stored in the memory 140, and calling data stored in the memory 140. Optionally, the processor 130 can be implemented in at least one hardware form of digital signal processing (DSP), field-programmable gate array (FPGA), and programmable logic array (PLA). The processor 130 can integrate one or a combination of a central processing unit (CPU), a graphics processing unit (GPU), a neural network processor (NPU), and a baseband chip. Among them, the CPU mainly processes the operating system, user interface, and application programs; the GPU is responsible for rendering and drawing the content that needs to be displayed on the touch display; the NPU is used to implement artificial intelligence (AI) functions; and the baseband chip is used to process wireless communications. It is understandable that the above baseband chip may not be integrated into the processor 130, but may be implemented by a separate chip.

[0089] The memory 140 may include a random access memory (RAM) or a read-only memory (ROM). Optionally, the memory 140 includes a non-transitory computer-readable storage medium. The memory 140 may be used to store instructions, programs, codes, code sets, or instruction sets. The memory 140 may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function (such as a touch function, a sound playback function, an image playback function, etc.), instructions for implementing the above various method embodiments, etc.; the data storage area may store data created according to the use of the computing device, etc.

[0090] In addition, those skilled in the art can understand that the structure of the computing device shown in the above drawings does not constitute a limitation on the computing device, and the computing device may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently. For example, the computing device also includes a display screen, a camera assembly, a microphone, a speaker, a radio frequency circuit, an input unit, a sensor (such as an acceleration sensor, an angular velocity sensor, a light sensor, etc.), an audio circuit, a WiFi module, a power supply, a Bluetooth module and other components, which will not be described in detail here.

[0091] Finally, see Fig.11 The present disclosure further provides a crystal pulling furnace 1, which includes: a crystal rod pulling device 80, a crucible lifting device 90, and a remelting control device 100 for the crystal rod according to the above technical solution.

[0092] It should be noted that the technical solutions described in the present disclosure can be combined arbitrarily without conflict.

[0093] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for controlling the melting back of a crystal rod, characterized in that: The remelting control method comprises step S1: during the remelting process of the shoulder of the crystal rod in the silicon melt in the quartz crucible, the bottom of the shoulder is melted so that the surface on which the shoulder is located is convex.

2. The method for controlling the melting back of a crystal rod according to claim 1, characterized in that: The distance between the highest point and the lowest point of the surface where the bottom of the shoulder is located in the axial direction of the crystal rod is in the range of 10 mm to 30 mm.

3. The method for controlling the melting back of a crystal rod according to claim 1 or 2, characterized in that: The remelting control method further includes step S2: controlling the remaining portion of the shoulder to move downward to remelt the portion of the remaining portion in the silicon melt, and repeating steps S1 and S2 until the remelting of the shoulder is completed.

4. The method for controlling the melting back of a crystal rod according to claim 1 or 2, characterized in that: During the process of melting back the shoulder of the crystal rod in the silicon melt in the quartz crucible, the bottom of the shoulder is melted so that the surface on which the shoulder is located is convex, including: During the remelting of the shoulder in the silicon melt, the first time length of the shoulder portion in the silicon melt is controlled to be within a range of 2 minutes to 10 minutes, so that the bottom of the shoulder is melted into a convex surface.

5. The method for controlling the melting back of a crystal rod according to claim 1 or 2, characterized in that: During the process of melting back the shoulder of the crystal rod in the silicon melt in the quartz crucible, before the bottom of the shoulder is melted so that the surface on which the shoulder is located is convex, the melting back control method further includes: When the equal-diameter section of the crystal rod is melted back to a point where the distance difference between the bottom of the equal-diameter section and the bottom of the shoulder is a set first distance, the quartz crucible is controlled to descend so that the distance between the liquid level of the silicon melt in the quartz crucible and the guide tube is a set second distance.

6. The method for controlling the melting back of a crystal rod according to claim 5, characterized in that: The second distance is in the range of 40 mm to 80 mm.

7. The method for controlling the melting back of a crystal rod according to claim 5, characterized in that: During the process of melting back the shoulder of the crystal rod in the silicon melt in the quartz crucible, before the bottom of the shoulder is melted so that the surface on which the shoulder is located is convex, the melting back control method further includes: When the equal-diameter section of the crystal rod is melted back so that the distance difference between the bottom of the equal-diameter section and the bottom of the shoulder is the first distance, controlling the rotation speed of the crystal rod to be within a range of 2 rpm to 5 rpm; Controlling the rotation speed of the quartz crucible to be within the range of 1 rev / min to 3 rev / min; and The magnetic induction intensity of the horizontal magnetic field is controlled to be in the range of 800Gs to 2000Gs.

8. The method for controlling the melting back of a crystal rod according to claim 7, characterized in that: Corresponding to each descent of the shoulder, the magnetic induction intensity of the horizontal magnetic field increases by 100 Gs to 500 Gs, until the magnetic induction intensity of the horizontal magnetic field is in the range of 2000 Gs to 3000 Gs.

9. The method for controlling the melting back of a crystal rod according to claim 5, characterized in that: During the process of melting back the shoulder of the crystal rod in the silicon melt in the quartz crucible, before the bottom of the shoulder is melted so that the surface on which the shoulder is located is convex, the melting back control method further includes: When the equal-diameter section of the crystal rod is melted back to a point where the distance difference between the bottom of the equal-diameter section and the bottom of the shoulder is a set third distance, the inert gas is controlled to purge the furnace and continue to purge for a second time period; wherein the third distance is smaller than the first distance.

10. The method for controlling the melting back of a crystal rod according to claim 9, characterized in that: When purging the furnace, the flow rate of the inert gas is in the range of 120 slpm to 150 slpm, and the second time period is in the range of 2 min to 5 min.

11. The method for controlling the melting back of a crystal rod according to claim 9, characterized in that: After the inert gas stops purging the furnace, the remelting control method further includes: When the crystal rod is controlled to descend until the bottom of the shoulder contacts the liquid surface of the silicon melt, the bottom heater is controlled to be turned off; and The temperature in the furnace corresponding to the process of melting back the shoulder is controlled to be 50° C. to 150° C. higher than the temperature in the furnace corresponding to the process of seeding the crystal rod.

12. The method for controlling the melting back of a crystal rod according to claim 11, characterized in that: The temperature in the furnace corresponding to the process of melting back the shoulder is controlled to be in the range of 1500° C. to 1700° C.

13. A melting back control device for a crystal rod, characterized in that: The remelting control device includes a remelting control unit; wherein, The remelting control part is configured to melt the bottom of the shoulder into a convex shape when the shoulder of the crystal rod is remelted in the silicon melt in the quartz crucible.

14. A remelting control device for a crystal rod, characterized in that: The remelting control device comprises: a processor and a memory; the processor is used to execute instructions stored in the memory to implement the remelting control method for a crystal rod according to any one of claims 1 to 12.

15. A crystal pulling furnace, characterized in that: The crystal pulling furnace comprises: a crystal rod pulling device, a crucible lifting device, and a remelting control device for the crystal rod according to claim 13 or 14.

16. A computer storage medium, characterized in that: At least one instruction is stored in the computer storage medium. When the at least one instruction is executed, the method for controlling the melting back of a crystal rod according to any one of claims 1 to 12 is implemented.

Images