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, controlling the quartz crucible to descend for a first distance within a first duration after a part of a crystal bar in a silicon melt in the quartz crucible is fused from the crystal bar; s2, controlling the residual part of the crystal bar to descend until the bottom of the crystal bar is in contact with the liquid level of the silicon melt, and keeping for a second duration; and S3, controlling the remaining part to descend by a second distance, so that the bottom is melted in the silicon melt to enable a third distance between the highest point and the lowest point of the surface where the bottom is located in the axial direction of the crystal bar to be smaller than a fourth distance.

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 the quartz crucible for melting back several times until the pulled part is completely melted and then the crystal rod is re-pulled. However, during the process of melting back the crystal rod, if the operation is improper, it may cause silicon melt sputtering (hereinafter referred to as "silicon sputtering"), which will not only interfere with the subsequent crystal rod pulling process, but also may 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 during the melting back process of the crystal rod 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 melting back control method comprising: Step S1: within a first time period after a portion of the crystal rod in the silicon melt in the quartz crucible is melted off the crystal rod, controlling the quartz crucible to descend a first distance; Step S2: controlling the remaining portion of the crystal rod to descend so that its bottom contacts the liquid surface of the silicon melt and remains in contact with the liquid surface for a second time period; Step S3: Control the remaining part to descend a second distance so that the bottom is melted in the silicon melt and the third distance between the highest point and the lowest point of the surface where the bottom is located in the axial direction of the crystal rod is less than the fourth distance; wherein the fourth distance is the distance between the highest point and the lowest point of the surface where the bottom of the crystal rod is located in the axial direction before the crystal rod is melted back.

[0007] In some possible implementations, the third distance is less than or equal to 3 mm.

[0008] In some possible implementations, the remelting control method further includes: Step S4: controlling the remaining portion to move downward along the axial direction to remelt the portion of the remaining portion in the silicon melt, and repeating steps S1 to S4 until the remelting of the crystal rod is completed.

[0009] In some possible implementations, the first duration and the second duration are both in the range of 10 s to 120 s, the first distance is in the range of 20 mm to 60 mm, and the second distance is in the range of 15 mm to 100 mm.

[0010] In some possible implementations, within a first time period after the portion of the crystal rod in the silicon melt in the quartz crucible is melted off from the crystal rod, before controlling the quartz crucible to descend a first distance, the remelting control method further includes: Controlling the rotation speed of the crystal rod to be reduced to 10% to 40% of the rotation speed of the crystal rod corresponding to when the crystal rod is pulled; The rotation speed of the quartz crucible is controlled to be adjusted to 0.5 rpm to 2 rpm; Controlling the magnetic induction intensity of the horizontal magnetic field to be reduced to 0 to 30% of the magnetic induction intensity corresponding to pulling the crystal rod; The heating power of the main heater is controlled to be reduced to 5% to 20% of the heating power corresponding to the main heater when pulling the crystal rod, and the heating power of the bottom heater is controlled to be reduced to 5% to 20% of the heating power corresponding to the bottom heater when pulling the crystal rod.

[0011] In some possible implementations, the reduced rotation speed of the crystal rod is in a range of 1 rpm to 3 rpm.

[0012] In some possible implementations, the reduced magnetic induction intensity of the horizontal magnetic field is in the range of 0 Gs to 1000 Gs.

[0013] In some possible implementations, the reduced heating power of the main heater is in the range of 105 kW to 120 kW, and the reduced heating power of the bottom heater is in the range of 10 kW to 20 kW.

[0014] In some possible implementations, within a first time period after the portion of the crystal rod in the silicon melt in the quartz crucible is melted off from the crystal rod, before controlling the quartz crucible to descend a first distance, the remelting control method further includes: The temperature in the furnace corresponding to the process of remelting the crystal rod is controlled to rise to 150° C. to 300° C. higher than the temperature in the furnace corresponding to the seeding process when pulling the crystal rod.

[0015] In some possible implementations, the furnace temperature corresponding to the process of remelting the crystal rod is in the range of 1950° C. to 2200° C.

[0016] In some possible implementations, the portion of the crystal rod in the silicon melt in the quartz crucible that is melted off the crystal rod and the contact between the bottom of the remaining portion of the crystal rod and the liquid surface of the silicon melt are monitored in real time by a contact sensing device.

[0017] In a second aspect, the present disclosure provides a remelting control device for a crystal rod, the remelting control device for a crystal rod comprising: a descending control unit and a holding control unit; wherein, The descending control unit is configured to control the quartz crucible to descend a first distance within a first time period after a portion of the crystal rod in the silicon melt in the quartz crucible is melted off from the crystal rod; and Controlling the remaining portion of the crystal rod to descend so that its bottom contacts the liquid surface of the silicon melt; The holding control unit is configured to control the bottom to maintain contact with the liquid surface of the silicon melt for a second time period; The descent control unit is further configured to control the remaining part to descend a second distance so that the bottom is melted in the silicon melt so that a third distance between the highest point and the lowest point of the surface where the bottom is located in the axial direction of the crystal rod is less than a fourth distance; wherein the fourth distance is the distance between the highest point and the lowest point of the surface where the bottom of the crystal rod is located in the axial direction before the crystal rod is melted back.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] The present disclosure provides a remelting control method for a crystal rod and its equipment, a crystal pulling furnace and a medium; within a first period of time after a portion of the crystal rod in the silicon melt in a quartz crucible is melted off from the crystal rod, the quartz crucible is controlled to descend a first distance, and then the remaining portion of the crystal rod is controlled to descend so that its bottom contacts the liquid surface of the silicon melt and is maintained for a second period of time, and finally the remaining portion is controlled to descend a second distance, so that the bottom is melted in the silicon melt so that the third distance between the highest point and the lowest point of the surface where the bottom of the crystal rod is located in the axial direction of the crystal rod is less than the fourth distance, and the fourth distance is the distance between the highest point and the lowest point of the surface where the bottom of the crystal rod is located in the axial direction before the crystal rod is remelted, thereby ensuring that after the portion of the crystal rod in the silicon melt is melted off from the main body of the crystal rod, the bottom of the remaining portion can be melted into a relatively flat state, thereby avoiding the occurrence of silicon splashing caused by the rupture of defects such as bubbles in the process of continuing to remelt the remaining portion of the crystal rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of a crystal pulling furnace in the related technology.

[0023] Figure 2 Schematic diagram of the convex solid-liquid interface of silicon melt in a quartz crucible.

[0024] 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.

[0025] Figure 4 A schematic diagram of the shape of the bottom of the remaining portion of the crystal rod after the portion of the crystal rod in the silicon melt in the quartz crucible is melted off the crystal rod is provided for an embodiment of the present disclosure.

[0026] 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.

[0027] Figure 6 A schematic diagram of the composition of a remelting control device for a crystal rod provided in an embodiment of the present disclosure.

[0028] Figure 7A structural block diagram of a remelting control device for a crystal rod provided in an embodiment of the present disclosure.

[0029] Figure 8 A schematic structural diagram of a crystal pulling furnace provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] The technical solutions in the present disclosure will be described clearly and completely below in conjunction with the accompanying drawings in the present disclosure.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] The furnace body 10 is provided with a cavity 101 therein.

[0035] 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.

[0036] 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.

[0037] The main heater 40 is distributed around the quartz crucible 20 .

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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 pulled crystal rod portion needs to be melted back. However, on the one hand, in the process of pulling the crystal rod S, due to the continuous change of the thermal field environment, it is difficult for the solid-liquid interface of the silicon melt in the quartz crucible 20 to always remain in a planar shape. Specifically, when the heat loss rate is lower than the heat input rate, the solid-liquid interface of the silicon melt in the quartz crucible 20 will present the following Figure 2 This is mainly because in the final stage of the crystal ingot S pulling, the heat dissipation conditions deteriorate, resulting in a decrease in the temperature gradient, and then a decrease in the supercooling of the solid-liquid interface of the silicon melt, causing the solid-liquid interface of the silicon melt to bulge toward the inside of the crystal ingot S with a lower temperature, thus forming Figure 2The convex solid-liquid interface in the crystal rod S. This convex solid-liquid interface will affect the bottom shape of the crystal rod S. Specifically, if the crystal growth rate in a certain direction is relatively slow, or the silicon melt in this direction is insufficient, it is possible that the bottom of the crystal rod S will form a concave shape that matches the convex solid-liquid interface. On the other hand, during the remelting process of the crystal rod S, if the temperature gradient difference causes the temperature of the silicon melt corresponding to the bottom area of ​​the crystal rod S to be higher than the temperature of the silicon melt corresponding to other parts, the silicon melt corresponding to the bottom area will flow faster to the surrounding area with lower temperature, which may also easily cause the bottom of the crystal rod S to form a concave shape during the remelting process. In addition, during the remelting process of the crystal rod S, the convection of the silicon melt may carry away the silicon melt corresponding to the bottom area of ​​the crystal rod S, thereby reducing the silicon melt in this area, causing the bottom of the crystal rod S to easily form a concave shape during the remelting process.

[0042] During the remelting process, when the bottom of the crystal ingot S is concave, as the crystal ingot S descends, some defects, such as bubbles, may gather at the concave portion of the bottom and expand downward during the remelting process of the crystal ingot S. When these bubbles gather at the bottom of the crystal ingot S, as the crystal ingot S is pressed downward, these bubbles are squeezed into the silicon melt, and as the crystal ingot S is pressed downward, they burst and cause the silicon melt to sputter.

[0043] 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.

[0044] Based on this, the present disclosure provides a method for controlling the melting back of a crystal rod to reduce the silicon splashing phenomenon during the melting back of the crystal rod. Figure 3 As shown, the remelting control method specifically includes the following steps.

[0045] In step S1 , within a first time period after a portion of the crystal ingot S in the silicon melt in the quartz crucible 20 is melted off from the crystal ingot S, the quartz crucible 20 is controlled to descend by a first distance.

[0046] It should be noted that in the related art, after the portion of the crystal rod S in the silicon melt in the quartz crucible 20 is melted off from the crystal rod S, the bottom of the remaining portion of the crystal rod S is concave, as shown in FIG. Figure 4 shown.

[0047] In step S1, after the portion of the crystal rod S in the silicon melt in the quartz crucible 20 is melted from the main body of the crystal rod S, the operation of the first duration is randomly started. During this first duration, the quartz crucible 20 is controlled to descend a first distance by the crucible lifting device 90. In this case, the liquid level distance of the silicon melt in the quartz crucible 20 can be increased, that is, the distance between the liquid surface of the silicon melt and the bottom of the guide tube 60, for example, is increased. The increase in the liquid level distance helps to reduce the convection effect between the surface of the silicon melt and other components in the furnace, because convection is caused by the difference in temperature gradient. Therefore, the increase in the liquid level distance can reduce this temperature gradient difference, reduce the convection intensity, and help stabilize the temperature gradient inside the silicon melt. This can prevent the temperature of the silicon melt corresponding to the bottom of the crystal rod S from being higher than other areas during the remelting process, thereby minimizing the risk of the bottom of the crystal rod S forming a concave shape during the remelting process.

[0048] In step S2, the remaining part of the crystal rod S is controlled to descend so that its bottom contacts the liquid surface of the silicon melt and is kept there for a second time period.

[0049] In step S2, by allowing the bottom of the remaining part of the crystal rod S to contact the liquid surface of the silicon melt and maintain it for a certain period of time, the temperature gradient and convection between the surface and the bottom of the remaining part of the crystal rod S can be utilized to make the heat distribution at the bottom of the remaining part of the crystal rod S more uniform, which helps to make the bottom of the remaining part of the crystal rod S relatively flat and avoid the above-mentioned concave shape.

[0050] Step S3: Control the remaining part to descend a second distance so that the bottom is melted in the silicon melt and the third distance between the highest point and the lowest point of the surface where the bottom is located in the axial direction of the crystal rod S is less than the fourth distance; wherein the fourth distance is the distance between the highest point and the lowest point of the surface where the bottom of the crystal rod is located in the axial direction before the crystal rod is melted back.

[0051] Through step S2, the heat distribution at the bottom of the remaining part of the crystal rod S can be made more uniform. On this basis, step S3 is performed, and due to the reduction of the temperature gradient difference and the reduction of the convection intensity, the bottom of the remaining part is uniformly melted in the silicon melt in the quartz crucible 20, so that the third distance between the highest point and the lowest point of the surface where the bottom of the remaining part of the crystal rod S is located in the axial direction of the crystal rod S after being melted in the silicon melt is smaller than the fourth distance before the crystal rod S is remelted, so that the bottom of the remaining part after melting can be made smoother, and then when the remaining part is further remelted, the occurrence of silicon splashing caused by the rupture of defects such as bubbles can be avoided.

[0052] In the present disclosure, within a first period of time after the portion of the crystal rod S in the silicon melt in the quartz crucible 20 is melted off from the crystal rod S, the quartz crucible 20 is controlled to descend a first distance, and then the remaining portion of the crystal rod S is controlled to descend so that its bottom contacts the liquid surface of the silicon melt and is maintained for a second period of time, and finally the remaining portion is controlled to descend a second distance, so that the bottom is melted in the silicon melt so that the third distance between the highest point and the lowest point of the surface where the bottom of the crystal rod S is located in the axial direction of the crystal rod S is smaller than the fourth distance between the highest point and the lowest point of the surface where the bottom of the crystal rod S is located in the axial direction before the crystal rod S is melted back. This ensures that after the portion of the crystal rod S in the silicon melt is melted off from the main body of the crystal rod S, the bottom of the remaining portion can be melted into a relatively flat state, thereby avoiding the occurrence of silicon splashing caused by the rupture of defects such as bubbles in the process of continuing to melt back the remaining portion of the crystal rod S.

[0053] for Figure 3 In the technical solution shown, in some possible implementations, the third distance is less than or equal to 3 mm.

[0054] According to the disclosure, Figure 4 As shown, when the bottom of the remaining part of the crystal rod S is melted in the silicon melt and the third distance Δd between the highest point and the lowest point of the surface where the bottom is located in the axial direction of the crystal rod S is less than 3 mm, the bottom is considered to be flat in the present disclosure. In this flat state, since there are no defects such as bubbles at the bottom of the crystal rod S, when the crystal rod S is continuously controlled to descend to continue to remelt the remaining part of the crystal rod S, the sputtering of the silicon melt caused by the bursting of bubbles can be effectively avoided, thereby preventing the occurrence of silicon sputtering.

[0055] for Figure 3 In some possible implementations of the technical solution shown, Figure 5 As shown, the remelting control method also includes the following steps.

[0056] In step S4, the remaining part is controlled to move downward in the axial direction to remelt the portion of the remaining part in the silicon melt, and steps S1 to S4 are repeated until the remelting of the crystal rod is completed.

[0057] During the remelting process of the crystal rod S, the crystal rod S needs to be inserted into the silicon melt in the quartz crucible 20 for remelting treatment for many times. Therefore, in the present disclosure, after the bottom of the remaining part is melted in the silicon melt, the remaining part is continuously controlled to move downward in the axial direction to remelt the portion of the remaining part in the silicon melt.

[0058] It can be understood that in the present disclosure, steps S1 to S4 are repeatedly performed until the crystal rod S is melted back.

[0059] for Figure 3 In some possible implementations of the technical solution shown, the first duration and the second duration are both in the range of 10 s to 120 s, the first distance is in the range of 20 mm to 60 mm, and the second distance is in the range of 15 mm to 100 mm.

[0060] In the present disclosure, by setting the first time duration within the range of 10 s to 120 s and the first distance within the range of 20 mm to 60 mm, the height position of the quartz crucible 20 can be quickly adjusted after the portion of the crystal ingot S in the silicon melt is melted from the main body of the crystal ingot S. Such a quick adjustment helps to stabilize the temperature gradient inside the silicon melt.

[0061] In the present disclosure, by setting the second time duration in the range of 10s to 120s and the second distance in the range of 15mm to 100mm, on the one hand, the contact time between the bottom of the remaining part of the crystal rod S and the silicon melt can be accurately controlled, and on the other hand, the length of the remaining part in the silicon melt can be controlled. In this case, the heat distribution at the bottom of the remaining part of the crystal rod S can be made more uniform, which helps to make the bottom of the remaining part of the crystal rod S flat.

[0062] It should be noted that, as the number of remelting increases, the corresponding second distance that the crystal rod S descends may gradually increase.

[0063] In addition, for crystal rods S with different diameters, as the diameter of the crystal rod S increases, the corresponding second descending distance of the crystal rod S decreases.

[0064] for Figure 3 In some possible implementations of the technical solution shown, within a first time period after the portion of the crystal rod in the silicon melt in the quartz crucible is melted off the crystal rod, before the quartz crucible is controlled to descend a first distance, the remelting control method further includes: Controlling the rotation speed of the crystal rod S to be reduced to 10% to 40% of the rotation speed of the crystal rod S corresponding to when the crystal rod S is pulled; The rotation speed of the quartz crucible 20 is controlled to be adjusted to 0.5 rpm to 2 rpm; The magnetic induction intensity of the horizontal magnetic field is controlled to be reduced to 0 to 30% of the magnetic induction intensity corresponding to when the crystal rod S is pulled; The heating power of the main heater 40 is controlled to be reduced to 5% to 20% of the heating power corresponding to the main heater 40 when the crystal rod S is pulled, and the heating power of the bottom heater 50 is controlled to be reduced to 5% to 20% of the heating power corresponding to the bottom heater 50 when the crystal rod S is pulled.

[0065] In the present disclosure, by reducing the rotation speed of the crystal rod S to 10% to 40% of the rotation speed when the crystal rod S is pulled, the smooth melting process can be ensured, and the drastic fluctuation of the temperature gradient of the silicon melt caused by the excessively fast change of the rotation speed of the crystal rod S can be reduced, thereby effectively avoiding the occurrence of silicon splashing. In some examples, the reduced rotation speed of the crystal rod S is in the range of 1 rpm to 3 rpm.

[0066] 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.

[0067] 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 reducing the magnetic induction intensity of the horizontal magnetic field, the convection of the silicon melt can be effectively reduced, thereby helping to maintain the stability and uniformity of the silicon melt during the remelting process, and reducing the uneven heat distribution and potential silicon splashing caused by convection. In some examples, the magnetic induction intensity of the reduced horizontal magnetic field is in the range of 0 Gs to 1000 Gs.

[0068] In addition to the aforementioned situations, during the remelting process, if the heating rate is too fast, the bottom of the crystal rod S may be unevenly melted in the silicon melt, resulting in a concave bottom. This uneven melting and the concave structure of the bottom may cause silicon melt sputtering during the subsequent remelting process. Therefore, in some examples, the reduced heating power of the main heater 40 is in the range of 105 kW to 120 kW, and the reduced heating power of the bottom heater 50 is in the range of 10 kW to 20 kW.

[0069] for Figure 3 In some possible implementations of the technical solution shown, within a first time period after the portion of the crystal rod in the silicon melt in the quartz crucible is melted off the crystal rod, before the quartz crucible is controlled to descend a first distance, the remelting control method further includes: The temperature in the furnace during the process of melting back the crystal rod is controlled to rise to 150° C. to 300° C. higher than the temperature in the furnace during the seeding process when pulling the crystal rod.

[0070] It is understandable that during the melting back of the crystal rod S, the temperature in the furnace has an important influence on the melting back of the crystal rod S. On the one hand, by controlling the temperature in the furnace during the melting back process, the melting back speed of the crystal rod S can be ensured, the smooth melting back of the crystal rod S can be ensured, and the melting back efficiency can be improved; on the other hand, by controlling the temperature in the furnace during the melting back process, it can help improve the uniformity of the temperature gradient distribution of the silicon melt, reduce the convection caused by the temperature gradient difference, thereby obtaining a more uniform melt and avoiding silicon splashing. In some examples, the furnace temperature corresponding to the melting back of the crystal rod is in the range of 1950°C to 2200°C.

[0071] for Figure 3 In some possible implementations of the technical solution shown, the portion of the crystal rod in the silicon melt in the quartz crucible is melted off the crystal rod and the contact between the bottom of the remaining portion of the crystal rod and the liquid surface of the silicon melt is monitored in real time by a contact sensing device.

[0072] It should be noted that, in some examples, the contact sensing device is used to determine whether the portion of the crystal rod S in the silicon melt in the quartz crucible is melted from the crystal rod S and whether the bottom of the remaining portion of the crystal rod S is in contact with the liquid surface of the silicon melt based on the changes in the monitored resistance value.

[0073] It can be understood that by real-time monitoring of the melting process of the crystal ingot S through the contact sensing device, the moment when the portion of the crystal ingot S in the silicon melt in the quartz crucible 20 is melted off from the crystal ingot S and the entire melting process can be accurately controlled, thereby ensuring the melting quality of the crystal ingot S and improving the safety of the melting process. In some examples, when the displayed value of the contact sensing device reaches 4000 to 6000, it indicates that the portion of the crystal ingot S in the silicon melt has been melted off from the main body of the crystal ingot S, and when the displayed value of the contact sensing device is greater than 7000, it indicates that the remaining portion of the crystal ingot S has dropped to the point where its bottom contacts the liquid surface of the silicon melt.

[0074] Based on the same inventive concept as the above technical solution, see Figure 6 , 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 descending control part 110 and a holding control part 120; wherein, The descending control unit 110 is configured to control the quartz crucible to descend a first distance within a first time period after the portion of the crystal rod in the silicon melt in the quartz crucible is melted off the crystal rod; and Controlling the remaining part of the crystal rod to descend so that its bottom contacts the liquid surface of the silicon melt; The holding control unit 120 is configured to control the bottom to be in contact with the liquid surface of the silicon melt for a second time period; The descent control unit 110 is also configured to control the remaining part to descend a second distance so that the bottom is melted in the silicon melt and the third distance between the highest point and the lowest point of the surface where the bottom is located in the axial direction of the crystal rod is less than the fourth distance; wherein the fourth distance is the distance between the highest point and the lowest point of the surface where the bottom of the crystal rod is located in the axial direction before the crystal rod is melted back.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] See also Figure 7, 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.

[0081] like Figure 7 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] Finally, see Figure 8 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.

[0086] It should be noted that the technical solutions described in the present disclosure can be combined arbitrarily without conflict.

[0087] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention 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: within a first time period after a portion of the crystal rod in the silicon melt in the quartz crucible is melted off the crystal rod, controlling the quartz crucible to descend a first distance; Step S2: controlling the remaining portion of the crystal rod to descend so that its bottom contacts the liquid surface of the silicon melt and remains in contact with the liquid surface for a second time period; Step S3: Control the remaining part to descend a second distance so that the bottom is melted in the silicon melt and the third distance between the highest point and the lowest point of the surface where the bottom is located in the axial direction of the crystal rod is less than the fourth distance; wherein the fourth distance is the distance between the highest point and the lowest point of the surface where the bottom of the crystal rod is located in the axial direction before the crystal rod is melted back.

2. The method for controlling the melting back of a crystal rod according to claim 1, characterized in that: The third distance is less than or equal to 3 mm.

3. The method for controlling the melting back of a crystal rod according to claim 1, characterized in that: The remelting control method further comprises: Step S4: controlling the remaining portion to move downward along the axial direction to remelt the portion of the remaining portion in the silicon melt, and repeating steps S1 to S4 until the remelting of the crystal rod is completed.

4. The method for controlling the melting back of a crystal rod according to any one of claims 1 to 3, characterized in that: The first duration and the second duration are both in the range of 10 s to 120 s, the first distance is in the range of 20 mm to 60 mm, and the second distance is in the range of 15 mm to 100 mm.

5. The method for controlling the melting back of a crystal rod according to any one of claims 1 to 3, characterized in that: Within a first time period after the portion of the crystal rod in the silicon melt in the quartz crucible is melted off from the crystal rod, before controlling the quartz crucible to descend a first distance, the remelting control method further includes: Controlling the rotation speed of the crystal rod to be reduced to 10% to 40% of the rotation speed of the crystal rod corresponding to when the crystal rod is pulled; The rotation speed of the quartz crucible is controlled to be adjusted to 0.5 rpm to 2 rpm; Controlling the magnetic induction intensity of the horizontal magnetic field to be reduced to 0 to 30% of the magnetic induction intensity corresponding to pulling the crystal rod; The heating power of the main heater is controlled to be reduced to 5% to 20% of the heating power corresponding to the main heater when pulling the crystal rod, and the heating power of the bottom heater is controlled to be reduced to 5% to 20% of the heating power corresponding to the bottom heater when pulling the crystal rod.

6. The method for controlling the melting back of a crystal rod according to claim 5, characterized in that: The reduced rotation speed of the crystal rod is in the range of 1 rev / min to 3 rev / min.

7. The method for controlling the melting back of a crystal rod according to claim 5, characterized in that: The magnetic induction intensity of the reduced horizontal magnetic field is in the range of 0 Gs to 1000 Gs.

8. The method for controlling the melting back of a crystal rod according to claim 5, characterized in that: The reduced heating power of the main heater is in the range of 105 kW to 120 kW, and the reduced heating power of the bottom heater is in the range of 10 kW to 20 kW.

9. The method for controlling the melting back of a crystal rod according to any one of claims 1 to 3, characterized in that: Within a first time period after the portion of the crystal rod in the silicon melt in the quartz crucible is melted off from the crystal rod, before controlling the quartz crucible to descend a first distance, the remelting control method further includes: The temperature in the furnace corresponding to the process of remelting the crystal rod is controlled to rise to 150° C. to 300° C. higher than the temperature in the furnace corresponding to the seeding process when pulling the crystal rod.

10. The method for controlling the melting back of a crystal rod according to claim 9, characterized in that: The corresponding furnace temperature during the process of remelting the crystal rod is in the range of 1950°C to 2200°C.

11. The method for controlling the melting back of a crystal rod according to any one of claims 1 to 3, characterized in that: The portion of the crystal rod in the silicon melt in the quartz crucible that is melted off the crystal rod and the contact between the bottom of the remaining portion of the crystal rod and the liquid surface of the silicon melt are monitored in real time by a contact sensing device.

12. A remelting control device for a crystal rod, characterized in that: The remelting control device for the crystal rod comprises: a descending control part and a holding control part; wherein, The descending control unit is configured to control the quartz crucible to descend a first distance within a first time period after a portion of the crystal rod in the silicon melt in the quartz crucible is melted off from the crystal rod; and Controlling the remaining portion of the crystal rod to descend so that its bottom contacts the liquid surface of the silicon melt; The holding control unit is configured to control the bottom to maintain contact with the liquid surface of the silicon melt for a second time period; The descent control unit is further configured to control the remaining part to descend a second distance so that the bottom is melted in the silicon melt so that a third distance between the highest point and the lowest point of the surface where the bottom is located in the axial direction of the crystal rod is less than a fourth distance; wherein the fourth distance is the distance between the highest point and the lowest point of the surface where the bottom of the crystal rod is located in the axial direction before the crystal rod is melted back.

13. A melting back control device for a crystal rod, characterized in that: The remelting control device for a crystal rod 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 11.

14. 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 12 or 13.

15. 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 11 is implemented.

Images