Crystal pulling furnace, control method thereof and computer readable storage medium

Abstract

The invention provides a crystal pulling furnace, a control method of the crystal pulling furnace and a computer readable storage medium. The crystal pulling furnace comprises a furnace body, a heat preservation unit, a guide cylinder, a guide cylinder lifting rod and an insulating part. A joint hole is formed in the furnace body; the heat preservation unit is arranged in the furnace body; the guide cylinder is arranged in the furnace body and at least partially located above the heat preservation unit, and the guide cylinder makes contact with the upper end of the heat preservation unit or is separated from the heat preservation unit; one part of the guide cylinder lifting rod is arranged in the furnace body and is connected with the guide cylinder, and the other part of the guide cylinder lifting rod penetrates through the joint hole and extends out of the furnace body; the insulating part is arranged between the guide cylinder lifting rod and the hole wall of the joint hole; the control method comprises the following steps: when the furnace body is grounded and the furnace body is connected in series with the guide cylinder lifting rod, the power supply supplies power to a circuit where the furnace body and the guide cylinder lifting rod are located; acquiring an electric signal between the furnace body and the guide cylinder lifting rod; judging whether the guide cylinder contacts with the upper end of the heat preservation unit according to the electric signal. The execution of the method can timely identify whether the guide cylinder is in contact with the upper end of the heat preservation unit.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of semiconductor production, and particularly relates to a crystal pulling furnace, a control method thereof and a computer readable storage medium. BACKGROUND

[0002] When growing silicon single crystal by using a crystal pulling furnace, because the density of liquid silicon is greater than that of solid silicon, the crucible cannot be filled with polycrystalline silicon raw material at one time when the polycrystalline silicon raw material is charged into the crystal pulling furnace, and a two-time charging method needs to be used. After the two-time charging, the polycrystalline silicon raw material is accumulated to a high level, so the flow guide cylinder needs to be lifted from the heat preservation unit, and then the flow guide cylinder is lowered to contact the upper end of the heat preservation unit after the polycrystalline silicon raw material is melted.

[0003] During the lowering of the flow guide cylinder, it is necessary to determine whether the flow guide cylinder contacts the upper end of the heat preservation unit in time, so as to avoid the flow guide cylinder from continuously lowering and damaging the heat preservation unit. In the prior art, an observer observes the lowering of the flow guide cylinder through a transparent window on the crystal pulling furnace, and determines whether the flow guide cylinder is lowered to the position according to the position of the scale on the lifting mechanism of the flow guide cylinder. This determination method has the problem of inaccurate manual determination. Moreover, in actual production, the height of the upper end of the heat preservation unit changes with different single crystals, and correspondingly, the lowering height of the flow guide cylinder also changes. If the observer does not identify the change in time, the flow guide cylinder will continue to lower after contacting the upper end of the heat preservation unit. SUMMARY

[0004] The present application aims to provide a crystal pulling furnace, a control method thereof and a computer readable storage medium, which are used for determining whether the flow guide cylinder contacts the upper end of the heat preservation unit in time during the lowering of the flow guide cylinder.

[0005] To achieve the above-mentioned purpose, the present application provides a control method of a crystal pulling furnace, the crystal pulling furnace comprising a furnace body, a heat preservation unit, a flow guide cylinder, a flow guide cylinder lifting rod and an insulating piece; the furnace body is provided with a joint hole; the heat preservation unit is located in the furnace body; the flow guide cylinder is located in the furnace body and at least partially above the heat preservation unit, and the flow guide cylinder contacts the upper end of the heat preservation unit or is separated from the heat preservation unit; a part of the flow guide cylinder lifting rod is located in the furnace body and connected with the flow guide cylinder, and the other part of the flow guide cylinder lifting rod extends to the outside of the furnace body through the joint hole, and the insulating piece is arranged between the flow guide cylinder lifting rod and the hole wall of the joint hole; the control method of the crystal pulling furnace comprises the following steps:

[0006] When the furnace body is grounded and the furnace body and the flow guide cylinder lifting rod are connected in series, a power supply supplies power to the circuit in which the furnace body and the flow guide cylinder lifting rod are located;

[0007] An electric signal between the furnace body and the flow guide cylinder lifting rod is acquired;

[0008] determining whether the draft tube is in contact with the upper end of the heat preservation unit according to the electrical signal.

[0009] Optionally, the electrical signal is in a first range when the draft tube is separated from the heat preservation unit, and the electrical signal is in a second range when the draft tube is in contact with the upper end of the heat preservation unit, the first range being different from the second range.

[0010] The step of determining whether the draft tube is in contact with the upper end of the heat preservation unit according to the electrical signal comprises:

[0011] Determining whether the draft tube is in contact with the upper end of the heat preservation unit according to the relationship between the electrical signal and the first range and the second range.

[0012] Optionally, the step of determining whether the draft tube is in contact with the upper end of the heat preservation unit according to the relationship between the electrical signal and the first range and the second range comprises:

[0013] When the electrical signal is in the first range, it is determined that the draft tube is separated from the heat preservation unit.

[0014] When the electrical signal is in the second range, it is determined that the draft tube is in contact with the upper end of the heat preservation unit.

[0015] Optionally, the second range has a standard variation amount relative to the first range.

[0016] The step of determining whether the draft tube is in contact with the upper end of the heat preservation unit according to the relationship between the electrical signal and the first range and the second range comprises:

[0017] Calculating an actual variation amount of the electrical signal relative to the first range.

[0018] Calculating a deviation of the actual variation amount from the standard variation amount.

[0019] Determining whether the deviation is within a preset deviation range, and if so, determining that the draft tube is in contact with the upper end of the heat preservation unit.

[0020] Optionally, the standard variation amount is calculated by formula (1) as follows:

[0021] ;

[0022] The actual variation amount is calculated by formula (2) as follows:

[0023] ;

[0024] wherein, represents the standard variation amount, represents the actual variation amount, represents the equivalent value of the first range, represents the equivalent value of the second range, represents the measured value of the electrical signal.

[0025] Optionally, the control method is executed in a process that the draft tube lifting rod drives the draft tube to move in a vertically downward direction.

[0026] The control method further comprises:

[0027] When it is determined that the draft tube is in contact with the upper end of the heat preservation unit, the movement of the draft tube lifting rod is controlled to stop.

[0028] Optionally, the electrical signal is a resistance signal or a current signal.

[0029] To achieve the above-mentioned purposes, the present application further provides a computer readable storage medium, which stores a program, when the program is executed, the control method of the crystal pulling furnace is executed.

[0030] To achieve the above-mentioned purposes, the present application further provides a crystal pulling furnace, comprising:

[0031] a furnace body, wherein a joint hole is arranged on the furnace body;

[0032] a heat preservation unit arranged in the furnace body;

[0033] a draft tube arranged in the furnace body and at least partially located above the heat preservation unit;

[0034] a draft tube lifting rod, wherein a part of the draft tube lifting rod is located in the furnace body and connected with the draft tube, and the other part of the draft tube lifting rod passes through the joint hole and extends to outside of the furnace body;

[0035] an insulating piece arranged between the draft tube lifting rod and the hole wall of the joint hole;

[0036] a signal acquisition module, comprising a power supply and a signal acquisition device, wherein the power supply, the furnace body and the draft tube lifting rod are connected in series to form a circuit, and the signal acquisition device is configured to acquire the electrical signal; and

[0037] a controller, which is communicatively connected with the signal acquisition element and is configured to execute the control method of the crystal pulling furnace.

[0038] Optionally, the signal acquisition device is a resistance detector or a current detector.

[0039] Compared with the prior art, the crystal pulling furnace, the control method thereof and the computer readable storage medium have the following advantages: the crystal pulling furnace comprises a furnace body, a heat preservation unit, a flow guide cylinder, a flow guide cylinder lifting rod and an insulating piece; the furnace body is provided with a joint hole; the heat preservation unit is located in the furnace body; the flow guide cylinder is located in the furnace body and at least partially above the heat preservation unit, and the flow guide cylinder is in contact with the upper end of the heat preservation unit or separated from the heat preservation unit; one part of the flow guide cylinder lifting rod is located in the furnace body and connected with the flow guide cylinder, and the other part extends to the outside of the furnace body through the joint hole, and the insulating piece is arranged between the flow guide cylinder lifting rod and the hole wall of the joint hole; the control method of the crystal pulling furnace comprises the following steps: when the furnace body is grounded and the furnace body and the flow guide cylinder lifting rod are connected in series, an electric power supply is used to supply power to a circuit in which the furnace body and the flow guide cylinder lifting rod are located; an electric signal between the furnace body and the flow guide cylinder lifting rod is acquired; and whether the flow guide cylinder is in contact with the upper end of the heat preservation unit is determined according to the electric signal. The control method of the crystal pulling furnace can be executed by a computer program, that is, the position of the flow guide cylinder is determined by executing the computer program instead of manually, so that whether the flow guide cylinder is in contact with the upper end of the heat preservation unit is identified in time during the process of lowering the flow guide cylinder after secondary feeding and melting of the polysilicon raw material, and the problem of crushing the heat preservation unit by the flow guide cylinder due to untimely identification is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0040] The accompanying drawings are used to better understand the present application and do not constitute an improper limitation on the present application. Among them:

[0041] Figure 1 is a structural schematic diagram of a crystal pulling furnace in the prior art;

[0042] Figure 2 is a structural schematic diagram of a crystal pulling furnace provided by the present application according to an embodiment;

[0043] Figure 3 is Figure 2 is an enlarged schematic diagram of the crystal pulling furnace at A shown in the figure;

[0044] Figure 4 is a flow chart of a control method of a crystal pulling furnace provided by the present application according to an embodiment;

[0045] Figure 5 is a partial flow chart of a control method of a crystal pulling furnace provided by the present application according to an embodiment.

[0046] [Reference signs are explained as follows]: 10, 100 - crystal pulling furnace, 11 - furnace body, 12 - crucible, 13 - crucible driving mechanism, 14 - heating unit, 15 - heat insulating unit, 16 - crystal pulling unit, 17 - convection cylinder, 171 - cylinder body, 172 - supporting part, 18 - convection cylinder lifting rod, 181 - cooling water flow channel, 19 - convection cylinder lifting rod driving mechanism, 21 - insulating member, 22 - signal acquisition module, 221 - power supply, 222 - signal collector, 23 - control unit. DETAILED DESCRIPTION

[0047] Other advantages and effects of the present application can be easily understood by those skilled in the art from the above description. The present application can also be implemented or applied in other different embodiments, and the details in the present description can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the drawings provided in the present embodiments only schematically illustrate the basic concepts of the present application, and thus the drawings only show the components related to the present application without drawing the components number, shape and size as in actual implementation. The actual implementation of each component type, number and proportion can be arbitrarily changed, and the component layout type can also be more complex.

[0048] In addition, each embodiment of the following description has one or more technical features, but this does not mean that the user must simultaneously implement all technical features in any embodiment, or can only separately implement one or all technical features in different embodiments. In other words, under the premise of implementation, those skilled in the art can selectively implement part or all of the technical features in any embodiment, or selectively implement a combination of part or all of the technical features in multiple embodiments, thereby increasing the flexibility of the implementation of the present application according to the disclosure of the present application, and according to the design specification or implementation requirements.

[0049] As used in this specification, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. As used in this specification, the term "or" is generally employed in its sense of "and / or" unless the content clearly dictates otherwise, and the term "have" or "has" is generally employed in its sense of "have or has at least one" or "has or has at least one" unless the content clearly dictates otherwise. The term "install," "connected," "connection" should be given the broadest possible interpretation including but not limited to fixedly connected, detachably connected, or integrally connected. It can be a mechanical connection, or an electrical connection. It can be a direct connection, or an indirect connection via an intermediate medium. It can be a communication within two elements, or an interaction between two elements. The relative terms "first," "second," and the like in the context of this specification are used merely to distinguish one entity or action from another, without necessarily requiring or implying any such actual relationship or order between or by them. It should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are merely used for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0050] For the convenience of understanding, the structure of the crystal pulling furnace in the prior art will be first described below in combination with the drawings. It should be noted that the drawings are very simplified and use non-precise proportions, only for the purpose of facilitating and clearly assisting the description of the embodiments of the present application. The same or similar reference numerals in the drawings represent the same or similar parts.

[0051] Figure 1 A structural schematic diagram of a crystal pulling furnace 10 in the prior art is shown. As shown in Figure 1 The crystal pulling furnace 10 in the prior art includes a furnace body 11, a crucible 12, a crucible driving mechanism 13, a heating unit 14, a heat preservation unit 15, a crystal pulling unit 16, a flow guide cylinder 17, a flow guide cylinder lifting rod 18, a flow guide cylinder lifting rod driving mechanism 19, and the like.

[0052] The furnace body 11 is a hollow structure, and the furnace body 11 is provided with a joint hole (not labeled in the drawing).

[0053] The crucible 12 is disposed in the furnace body 11 and can include a quartz crucible and a graphite crucible, with the quartz crucible being located in the graphite crucible.

[0054] The crucible driving mechanism 13 is partially located in the furnace body 11 and is used to drive the crucible 12 to ascend and descend and rotate.

[0055] The heating unit 14 is disposed in the furnace body 11 and is used to heat the crucible 12. The heating unit 14 can be a graphite heater.

[0056] The heat-insulating unit 15 is disposed in the furnace body 11 and is located between the crucible 12 and the furnace body 11. The heat-insulating unit 15 is usually made of carbon felt and is used to maintain the temperature in the furnace body 11.

[0057] The crystal pulling unit 16 is partially disposed in the furnace body 11.

[0058] The draft tube 17 is a graphite-made inverted conical shield disposed in the furnace body 11 and at least partially located above the heat-insulating unit 15 and arranged around the crystal growth area. Specifically, the draft tube 17 includes a tube body 171 and a supporting portion 172 connected to the outer circumferential surface of the upper end of the tube body 171. The outer diameter of the tube body 171 is smaller than the inner diameter of the heat-insulating unit 15, and the outer diameter of the supporting portion 172 is not smaller than the inner diameter of the heat-insulating unit 15. The tube body 171 can be at least partially located inside the heat-insulating unit 15, and the supporting portion 172 is located above the heat-insulating unit 15 and in contact with the upper end of the heat-insulating unit 15 or is spaced apart from the upper end of the heat-insulating unit 15. When the supporting portion 172 is in contact with the upper end of the heat-insulating unit 15, the draft tube 17 is in contact with the upper end of the heat-insulating unit 15, and when the supporting portion 172 is spaced apart from the upper end of the heat-insulating unit 15, the draft tube 17 is separated from the heat-insulating unit 15.

[0059] The draft tube lifting rod 18 is partially located in the furnace body 11 and connected to the draft tube 17, and the other part extends out of the furnace body 11 through the joint hole and is connected to the draft tube lifting rod driving mechanism 19. The draft tube lifting rod 18 is used to move in the vertical direction under the drive of the draft tube lifting rod driving mechanism 19 to drive the draft tube 17 to move in the vertical direction.

[0060] When a single crystal ingot is grown using the crystal pulling furnace, the polycrystalline silicon raw material is loaded in the quartz crucible, the heating unit 14 heats the crucible 12 to melt the polycrystalline silicon raw material into a melt and keep it in a molten state. A seed crystal connected to the crystal pulling unit 16 is inserted into the surface of the melt to be welded, the crystal pulling unit 16 rotates the seed crystal, the crucible driving mechanism 13 drives the crucible 12 to rotate in the opposite direction, and the crystal pulling unit 16 also slowly lifts the seed crystal upwards, and after the processes of seeding, shoulder opening, shoulder turning, diameter growth, and tailing, a crystal ingot with the desired diameter and length is finally grown. Those skilled in the art know that argon is continuously introduced into the furnace body 11 during the crystal growth process.

[0061] During the growth of the crystal ingot, the supporting part 172 is in contact with the upper end of the heat preservation unit 15, so that the flow guide cylinder 17 is in contact with the upper end of the heat preservation unit 15, which adjusts the flow direction and flow rate of argon, concentrates the downward blowing argon near the crystal growth interface, and prevents the high-temperature liquid surface and the crucible 12 from radiating heat to the cooling crystal, thereby improving the heat output of the crystal surface to the surrounding and the temperature gradient of the crystal side.

[0062] Because the density of liquid silicon is greater than that of solid silicon, when the crystal pulling furnace is loaded, the crucible 12 cannot be filled at one time, and a two-time loading method needs to be used. After two-time loading, the polycrystalline silicon raw material is accumulated on the melt. In order to avoid the flow guide cylinder 17 from being scratched by the accumulated polycrystalline silicon raw material, the flow guide cylinder lifting rod driving mechanism 19 is used to drive the flow guide cylinder lifting rod 18 to move upwards, and the flow guide cylinder 17 is moved upwards by a certain distance, which causes the supporting part 172 to be spaced above the heat preservation unit 15 before the polycrystalline silicon raw material is melted, and the flow guide cylinder 17 is separated from the heat preservation unit 15. Accordingly, after the polycrystalline silicon raw material is melted, the flow guide cylinder lifting rod driving mechanism 19 is used to drive the flow guide cylinder lifting rod 18 to move downwards to move the flow guide cylinder 17 downwards until the flow guide cylinder 17 is in contact with the upper end of the heat preservation unit 15 again.

[0063] In the prior art, whether the flow guide cylinder 17 is in contact with the upper end of the heat preservation unit 15 during the descent of the flow guide cylinder 17 is determined by artificial observation. This method cannot timely identify the contact between the flow guide cylinder 17 and the upper end of the heat preservation unit 15, which may cause the flow guide cylinder 17 to crush the heat preservation unit 15.

[0064] The inventor of the present application has found that, when the furnace body 11 is grounded, if the flow guide cylinder lifting rod 18 is insulated from the furnace body 11 at the joint hole, and a power supply is connected in series with the flow guide cylinder lifting rod 18 and the furnace body 11 to form a circuit, and the power supply is powered, the resistance or current between the flow guide cylinder lifting rod 18 and the furnace body 11 is significantly different when the flow guide cylinder 17 is separated from the heat preservation unit 15 and when the flow guide cylinder 17 is in contact with the upper end of the heat preservation unit 15. Based on this, the inventor considers that the change of the resistance or current between the flow guide cylinder lifting rod 18 and the furnace body 11 can be used to determine whether the flow guide cylinder 17 is separated from the heat preservation unit 15 or in contact with the upper end of the heat preservation unit 15 during the process of moving the flow guide cylinder 17 downward by the flow guide cylinder lifting rod 18.

[0065] Therefore, the embodiment of the present application provides a crystal pulling furnace 100 as shown in Figure 2 and Figure 3 As shown in Figure 2 and Figure 3 The crystal pulling furnace 100 includes the furnace body 11, the heating unit 14, the heat preservation unit 15, the flow guide cylinder 17, the flow guide cylinder lifting rod 18, the flow guide cylinder lifting rod driving mechanism 19, and the like, and further includes an insulating piece 21, a signal acquisition module 22, and a control unit 23.

[0066] The specific structure and arrangement of the furnace body 11, the heating unit 14, the heat preservation unit 15, the flow guide cylinder 17, the flow guide cylinder lifting rod 18, and the flow guide cylinder lifting rod driving mechanism 19 can refer to the prior art described above, which will not be described again here.

[0067] The insulating piece 21 is arranged between the flow guide cylinder lifting rod 18 and the hole wall of the joint hole, so that the flow guide cylinder lifting rod 18 is insulated from the furnace body 11 at the joint hole.

[0068] The signal acquisition module 22 includes a power supply 221 and a signal acquisition device 222, and the power supply 221, the flow guide cylinder lifting rod 18, and the furnace body 11 are connected in series through any suitable conductive member such as a wire. The signal acquisition device 222 is configured to acquire the electrical signal between the flow guide cylinder lifting rod 18 and the furnace body 11 when the power supply 221 is powered.

[0069] The control unit 23 is communicatively connected to the signal acquisition module 22 and is configured to execute a control method for a crystal pulling furnace. The control method is executed when the furnace body 11 is grounded and the guide tube lifting rod drive mechanism 19 drives the guide tube lifting rod 18 to move vertically downwards, thereby moving the guide tube 17 vertically downwards. The flow of the control method is as follows: Figure 4 As shown, it includes the following steps S1, S2 and S3.

[0070] Step S1 includes: energizing the power supply 221.

[0071] Step S2 includes: acquiring the electrical signal between the furnace body 11 and the guide tube lifting rod 18.

[0072] Step S3 includes: determining whether the guide tube 17 is in contact with the upper end of the heat preservation unit 15 based on the electrical signal.

[0073] If the judgment result of step S3 is "yes", then the guide tube lifting rod drive mechanism 19 is controlled to stop driving the guide tube lifting rod 18 to move downward in any suitable way. If the judgment result of step S3 is "no", then the process returns to step S2.

[0074] By executing the control method, it is possible to determine in a timely manner whether the guide tube 17 is in contact with the upper end of the insulation unit 15, and thus control the guide tube 17 to stop descending in a timely manner. This avoids the situation where the guide tube 17 continues to move downward after it has already contacted the upper end of the insulation unit 15 due to untimely identification during manual observation, which could result in the insulation unit 15 being crushed.

[0075] In this embodiment of the invention, the electrical signal can be either a resistance signal or a current signal. It is understood that when the electrical signal is a resistance signal, the signal acquisition device 222 is a resistance detector. When the electrical signal is a current signal, the signal acquisition device 222 is a current detector. Furthermore, the insulating component 21 can be made of any suitable insulating material, such as Teflon.

[0076] It can also be understood that the communication connection between the control unit 23 and the signal acquisition module 22 includes the communication connection between the control unit 23 and the power supply 221 so that the control unit 23 can control the power supply 221 to supply power or stop supplying power, and the communication connection between the control unit 23 and the signal acquisition device 222 so that the control unit 23 can receive the electrical signal acquired by the signal acquisition device 222.

[0077] The skilled in the art knows that the cooling water flow channel 181 is arranged in the draft tube lifting rod 18 for the cooling water flow, and the cooling water is approximately pure water, which has a large resistance. When the draft tube 17 is separated from the heat preservation unit 15, the furnace body 11 is grounded, and the insulating member 21 exists, so that the electric energy flows to the cooling water. In this case, the resistance between the draft tube lifting rod 18 and the furnace body 11 is approximately equal to the sum of the resistance of the draft tube lifting rod 18 and the resistance of the cooling water, which has a large value, and accordingly, the current between the draft tube lifting rod 18 and the furnace body 11 is small. As described above, the draft tube 17 is made of graphite, and the material of the heat preservation unit 15 is carbon felt, both of which have good conductivity, and the resistance is much smaller than that of pure water. This makes the electric energy no longer flow to the cooling water when the upper end of the draft tube 17 contacts the heat preservation unit 15, but flow among the draft tube lifting rod 18, the draft tube 17, the heat preservation unit 15 and the furnace body 11, so that the resistance between the draft tube lifting rod 18 and the furnace body 11 is approximately equal to the sum of the resistance of the draft tube lifting rod 18 and the resistance of the heat preservation unit 15. That is, when the upper end of the draft tube 17 contacts the heat preservation unit 15, the resistance between the draft tube 17 and the heat preservation unit 15 is small, and the current is large.

[0078] When the draft tube 17 is separated from the heat preservation unit 15, the electric signal between the draft tube lifting rod 18 and the furnace body 11 is called the first electric signal, and when the upper end of the draft tube 17 contacts the heat preservation unit 15, the electric signal between the draft tube lifting rod 18 and the furnace body 11 is called the second electric signal. Thus, when the electric signal is a resistance signal, the first electric signal is greater than the second electric signal; when the electric signal is a current signal, the first electric signal is smaller than the second electric signal.

[0079] In practice, due to the quality of the cooling water and other factors, the first electric signal also fluctuates within a certain range, which is called the first range. The contact area between the draft tube 17 and the heat preservation unit 15 may fluctuate due to equipment vibration or other reasons, resulting in the second electric signal also fluctuating within a certain range, which can be called the second range. It is easy to understand that the second range is different from the first range.

[0080] The operation of the step S3 can include judging whether the draft tube 17 contacts the upper end of the heat preservation unit 15 according to the relationship between the electric signal and the first range and the second range.

[0081] In an optional example, the operation of the step S3 more specifically comprises: determining that the flow guide cylinder 17 is separated from the heat preservation unit 15 when the electrical signal is in the first range. Determining that the flow guide cylinder 17 is in contact with the upper end of the heat preservation unit 15 when the electrical signal is in the second range.

[0082] Further preferably, the electrical signal is in the second range within a preset time length, it is determined that the flow guide cylinder 17 is in contact with the upper end of the heat preservation unit 15. In this way, the judgment accuracy can be improved to avoid misjudgment.

[0083] In a specific embodiment, the electrical signal is a resistance signal, and the first range is 1.9MΩ-2MΩ, and the second range is 15Ω-200Ω. It can be seen that the first range and the second range are significantly different. In an actual operation, the resistance values measured before t1 time are all in the first range, the resistance value measured at t1 time is 115Ω, and the resistance values measured in the next preset time length are all between 20Ω-100Ω. Therefore, it can be determined that the flow guide cylinder 17 is in contact with the upper end of the heat preservation unit 15.

[0084] In another optional example, the second range has a standard variation relative to the first range, and the flow of the step S3 is as shown in Figure 5 , comprising steps S31, S32 and S33.

[0085] The step S31 comprises: calculating the actual variation of the electrical signal relative to the first range.

[0086] The step S32 comprises: calculating the deviation ΔA between the actual variation and the standard variation.

[0087] The step S33 comprises: judging whether the deviation ΔA is within a preset deviation range, if yes, determining that the flow guide cylinder 17 is in contact with the upper end of the heat preservation unit 15, if not, determining that the flow guide cylinder 17 is separated from the heat preservation unit 15.

[0088] Wherein, the standard variation is calculated by formula (1), formula (1) is: The actual variation is calculated by formula (2), formula (2) is: Wherein, represents the standard variation, represents the actual variation, represents the equivalent value of the first range, represents the equivalent value of the second range, represents the measured value of the electrical signal.

[0089] Optionally, the deviation ΔA between the actual variation and the standard variation can be a percentage of the absolute value of the difference between the actual variation and the standard variation relative to the standard variation, i.e., The deviation range is, for example, within ±a%, a being a constant, which is set according to actual conditions.

[0090] In a preferred example, when all the deviations within the preset time length are within the deviation range, it is determined that the draft tube 17 is in contact with the upper end of the heat preservation unit 15. In this way, the misjudgment can be reduced, and the judgment accuracy can be improved.

[0091] It should be understood that the first range and the second range can both be determined by actual measurement before the control method is performed. In the process of measuring the first range, the draft tube 17 is separated from the heat preservation unit 15; in the process of measuring the second range, the draft tube 17 is in contact with the upper end of the heat preservation unit 15.

[0092] In some examples, the equivalent value X1 of the first range is the median value of the first range, and the equivalent value X2 of the second range is the median value of the second range. It should be known that the median value of a range is equal to the average value of the upper limit value and the lower limit value of the range.

[0093] In other examples, the equivalent value X1 of the first range is the average value of a plurality of the electrical signals measured when the first range is determined, and the equivalent value X2 of the second range is the average value of a plurality of the electrical signals measured when the second range is determined.

[0094] In addition, it should be noted that in practice, the quality of the cooling water meets the set qualified standard, and in this case, the first range can remain unchanged. However, when the quality of the cooling water changes significantly, for example, when the qualified standard changes, the first range should be re-determined.

[0095] In further embodiments, as shown in Figure 2 The control unit 23 is also in communication connection with the draft tube lifting rod driving mechanism 19, and as shown in Figure 4 The control method further includes a step S4 performed when the determination result of the step S3 is “Yes”, and the step S4 includes: controlling the draft tube lifting rod driving mechanism 19 to stop driving the draft tube lifting rod 18 to move downward. In this way, the draft tube lifting rod 18 does not need to be manually controlled to stop moving.

[0096] The second purpose of the embodiments of the present application is to provide a control method of a crystal pulling furnace, which comprises at least the steps S1, S2 and S3 as described above, and can further comprise the step S4.

[0097] The third purpose of the embodiments of the present application is to provide a computer readable storage medium, which stores a program, when the program is executed, the control method of the crystal pulling furnace as described above is executed.

[0098] Although the present application has been disclosed as above, it is not limited thereto. Those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for controlling a crystal pulling furnace, characterized in that, The crystal pulling furnace includes a furnace body, a heat preservation unit, a flow guide tube, a flow guide tube lifting rod, and an insulating component; the furnace body is provided with a joint hole; the heat preservation unit is located inside the furnace body; the flow guide tube is located inside the furnace body and is at least partially located above the heat preservation unit, the flow guide tube is in contact with or separate from the heat preservation unit; a portion of the flow guide tube lifting rod is located inside the furnace body and connected to the flow guide tube, and another portion passes through the joint hole and extends to the outside of the furnace body; The insulating component is disposed between the guide tube lifting rod and the wall of the connecting hole; the control method of the crystal pulling furnace includes: When the furnace body is grounded and the furnace body is connected in series with the guide tube lifting rod, a power source supplies power to the circuit where the furnace body and the guide tube lifting rod are located; Acquire the electrical signal between the furnace body and the guide tube lifting rod; The electrical signal is used to determine whether the guide tube is in contact with the upper end of the insulation unit.

2. The control method for a crystal pulling furnace according to claim 1, characterized in that, When the guide tube separates from the insulation unit, the electrical signal is within a first range; when the guide tube contacts the upper end of the insulation unit, the electrical signal is within a second range, and the first range is different from the second range. The step of determining whether the guide tube is in contact with the upper end of the insulation unit based on the electrical signal includes: Based on the relationship between the electrical signal and the first range and the second range, it is determined whether the guide tube is in contact with the upper end of the heat preservation unit.

3. The control method for a crystal pulling furnace according to claim 2, characterized in that, The step of determining whether the guide tube is in contact with the upper end of the heat preservation unit based on the relationship between the electrical signal and the first range and the second range includes: When the electrical signal is within the first range, it is determined that the guide tube and the heat preservation unit are separated; When the electrical signal is within the second range, it is determined that the guide tube is in contact with the upper end of the heat preservation unit.

4. The control method for a crystal pulling furnace according to claim 2, characterized in that, The second range has a standard variation relative to the first range; The step of determining whether the guide tube is in contact with the upper end of the heat preservation unit based on the relationship between the electrical signal and the first range and the second range includes: Calculate the actual change of the electrical signal relative to the first range; Calculate the deviation between the actual change and the standard change; Determine whether the deviation is within a preset deviation range. If so, determine that the guide tube is in contact with the upper end of the insulation unit.

5. The control method for a crystal pulling furnace according to claim 4, characterized in that, The standard variation is calculated using the following formula (1): ； The actual change is calculated using the following formula (2): ； in, This represents the standard change. This represents the actual amount of change. This represents the equivalent value within the first range. This represents the equivalent value of the second range. This represents the measured value of the electrical signal.

6. The control method for a crystal pulling furnace according to claim 1, characterized in that, The control method is executed during the process of the guide tube lifting rod driving the guide tube to move in a vertically downward direction; The control method further includes: When it is determined that the guide tube is in contact with the upper end of the insulation unit, the lifting rod of the guide tube is controlled to stop moving.

7. The control method for a crystal pulling furnace according to claim 1, characterized in that, The electrical signal is a resistance signal or a current signal.

8. A computer-readable storage medium having a program stored thereon, characterized in that, When the program is executed, the control method for the crystal pulling furnace as described in any one of claims 1-7 is performed.

9. A crystal pulling furnace, characterized in that, include: Furnace body, wherein the furnace body is provided with a connecting hole; The heat preservation unit is installed inside the furnace body; A flow guide tube is disposed inside the furnace body and is located at least partially above the insulation unit; A guide tube lifting rod, a portion of which is located inside the furnace body and connected to the guide tube, and another portion passing through the joint hole and extending outside the furnace body; An insulating component is disposed between the lifting rod of the guide tube and the wall of the connecting hole; The signal acquisition module includes a power supply and a signal acquisition device. The power supply, the furnace body, and the guide tube lifting rod are connected in series to form a circuit. The signal acquisition device is configured to acquire the electrical signal. as well as, The controller is communicatively connected to the signal acquisition element and is configured to perform the control method for the crystal pulling furnace as described in any one of claims 1-7.

10. The crystal pulling furnace according to claim 8, characterized in that, The signal acquisition device is a resistance detector or a current detector.

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