Single crystal furnace and crystal pulling method

Abstract

The embodiment of the invention relates to the technical field of monocrystalline silicon material preparation, and provides a single crystal furnace and a crystal pulling method, and the single crystal furnace comprises a furnace body auxiliary chamber with a temperature measurement interface; the first end of the temperature measuring device is provided with a temperature measuring part, the first end of the temperature measuring device extends into the through hole of the seed crystal from the clamping end of the seed crystal and extends out of the growth end of the seed crystal, the second end of the temperature measuring device is electrically connected with the temperature measuring interface through a signal line, and the first end and the second end of the temperature measuring device are two opposite ends; wherein the central axis of the through hole is parallel to the central axis of the seed crystal. The solar cell provided by the embodiment of the invention at least can improve the photoelectric conversion efficiency of the solar cell. According to the single crystal furnace, temperature and temperature gradient information is obtained through actual measurement of the temperature measuring device, the accuracy is greatly improved, temperature values of different positions in a solution and on the central axis of a crystal in the actual crystal pulling process can be measured, and an accurate data basis is provided for seed crystal growth.

Description

Technical Field

[0001] This application relates to the photovoltaic field, and in particular to a single crystal furnace and a crystal pulling method. Background Technology

[0002] Temperature is the most fundamental and important parameter in Czochralski crystal growth. It is the driving force for silicon melting and crystallization, and it determines crystal quality such as oxygen content and micro-defect density by affecting melt flow and crystal thermal stress. However, in existing technologies, temperature measurements during crystal pulling are limited in number and accuracy. Summary of the Invention

[0003] This application provides a single crystal furnace and a crystal pulling method, which at least solves the problem that in the prior art, temperature measurement during the crystal pulling process has not only few measurement points but also low accuracy.

[0004] According to some embodiments of this application, one aspect of this application provides a single crystal furnace, including: a furnace sub-chamber having a temperature measuring interface; a temperature measuring device, the first end of the temperature measuring device having a temperature measuring part, the first end of the temperature measuring device extending from the clamping end of the seed crystal into the through hole of the seed crystal and extending out from the growth end of the seed crystal, the second end of the temperature measuring device being electrically connected to the temperature measuring interface via a signal line, the first end and the second end of the temperature measuring device being opposite ends; wherein, the central axis of the through hole is parallel to the central axis of the seed crystal.

[0005] In some embodiments, the temperature measuring device includes a plurality of thermocouples, one end of each thermocouple passing through the through hole and extending from the growth end of the seed crystal, the end of each thermocouple extending from the growth end of the seed crystal forming a temperature measuring point, and the temperature measuring points of the plurality of thermocouples forming the temperature measuring part; there are a plurality of temperature measuring interfaces, and the plurality of temperature measuring interfaces are arranged one-to-one with the plurality of thermocouples, and the end of each thermocouple away from the temperature measuring point is connected to the corresponding temperature measuring interface through a signal line; wherein, the temperature measuring points of the plurality of thermocouples are distributed along the axial direction of the seed crystal.

[0006] In some embodiments, the temperature measuring device includes a first thermocouple and a second thermocouple. The end of the first thermocouple extending from the growth end of the seed crystal is a first temperature measuring point, and the end of the second thermocouple extending from the growth end of the seed crystal is a second temperature measuring point. The distance between the first temperature measuring point and the growth end of the seed crystal is greater than the distance between the second temperature measuring point and the growth end of the seed crystal. The temperature measuring interface is at least two, including a first temperature measuring interface and a second temperature measuring interface. The end of the first thermocouple furthest from the first temperature measuring point is connected to the first temperature measuring interface via a signal line, and the end of the second thermocouple furthest from the second temperature measuring point is connected to the second temperature measuring interface via a signal line.

[0007] In some embodiments, each thermocouple includes: a first coupling wire, a second coupling wire, a first insulating layer, and a second insulating layer. The end of the first coupling wire that contacts the second coupling wire is the temperature measuring point. The first insulating layer is wrapped around the first coupling wire and the second coupling wire, and the second insulating layer is located between the first coupling wire and the second coupling wire.

[0008] In some embodiments, the temperature measuring device further includes an outer sheath for completely enclosing the plurality of thermocouples.

[0009] In some embodiments, the single crystal furnace further includes an adhesive layer located between the outer sheath and the sidewall of the through hole.

[0010] In some embodiments, the single crystal furnace further includes a temperature measuring instrument, which is electrically connected to the temperature measuring device via the temperature measuring interface, and is used to convert the electrical signal of the temperature measuring device into a digital signal.

[0011] According to some embodiments of this application, another aspect of this application provides a crystal pulling method, including: performing crystal pulling using any of the single crystal furnaces described above; during the crystal pulling process, using a temperature measuring device of the single crystal furnace to detect the temperature data in real time during the crystal pulling process, and determining the crystal pulling parameters of the crystal pulling process based on the temperature data, the crystal pulling process including a fusion stage, a crystal pulling stage, a shoulder forming stage, a shoulder turning stage, a constant diameter stage, and a finishing stage, the temperature data including at least the melt temperature, the solid-liquid interface temperature, and the crystal temperature, and the crystal pulling parameters including at least the crystal rotation speed, the crucible rotation speed, and the crystal pulling speed.

[0012] In some embodiments, the temperature measuring device includes a first thermocouple and a second thermocouple. The end of the first thermocouple extending from the growth end of the seed crystal is a first temperature measuring point, and the end of the second thermocouple extending from the growth end of the seed crystal is a second temperature measuring point. The distance between the first temperature measuring point and the growth end of the seed crystal is greater than the distance between the second temperature measuring point and the growth end of the seed crystal. During the crystal pulling process, the temperature measuring device of the single crystal furnace is used to detect the temperature data in real time during the crystal pulling process, and the crystal pulling parameters of the crystal pulling process are determined based on the temperature data. This includes: acquiring the temperature data of the first temperature measuring point and the temperature data of the second temperature measuring point during the crystal pulling process to obtain first temperature data and second temperature data, respectively; acquiring the distance between the temperature measuring points and determining the difference between the first temperature data and the second temperature data as a temperature difference value, wherein the distance between the temperature measuring points is the distance between the first temperature measuring point and the second temperature measuring point along the central axis direction of the seed crystal; determining the ratio between the temperature difference value and the distance between the temperature measuring points as a temperature gradient, and determining the crystal pulling parameters of the crystal pulling process based on the temperature gradient.

[0013] In some embodiments, during the welding stage, the first temperature data is a first melt temperature, the second temperature data is a second melt temperature, the temperature gradient is a melt temperature gradient, and determining the crystal pulling parameters of the crystal pulling process based on the temperature gradient includes: determining the melt flowability parameters based on the melt temperature gradient; and determining the crystal rotation speed, the crucible rotation speed, the heater length, and the heater position based on the melt flowability parameters.

[0014] In some embodiments, during the shoulder formation stage, the first temperature data is a first solid-liquid interface temperature, the second temperature data is a second solid-liquid interface temperature, and the temperature gradient is a solid-liquid interface temperature gradient. Determining the crystal pulling parameters based on the temperature gradient includes: determining the crystal pulling speed based on the solid-liquid interface temperature gradient, such that the difference between the crystal growth parameter ratio and a preset ratio is within a preset range, wherein the growth parameter ratio is the ratio of the crystal growth speed to the temperature gradient, and the crystal pulling speed is directly proportional to the solid-liquid interface temperature gradient.

[0015] In some embodiments, during the constant diameter stage, the temperature data includes the crystal temperature. Determining the crystal pulling parameters based on the temperature data includes: determining the cooling parameters of the crystal based on the crystal temperature. The cooling parameters include the installation position of the cooling device and the cooling temperature of the cooling device, and the crystal temperature and the cooling temperature of the cooling device have a corresponding relationship.

[0016] The technical solution provided in this application has at least the following advantages: A single crystal furnace includes a furnace sub-chamber with a temperature measurement interface; a temperature measuring device, the first end of which has a temperature measuring section, extending from the clamping end of the seed crystal into the through hole of the seed crystal and extending out from the growth end of the seed crystal; the second end of which is electrically connected to the temperature measurement interface via a signal line; the first end and the second end of the temperature measuring device are opposite ends; wherein, the central axis of the through hole is the central axis of the seed crystal. This single crystal furnace obtains temperature and temperature gradient information through actual measurement using the temperature measuring device, significantly improving accuracy. It can also measure temperature values ​​at different positions in the melt and along the crystal's central axis during the actual crystal pulling process, providing an accurate data basis for seed crystal growth and solving the problem in the prior art where temperature measurement during crystal pulling involves few measurement points and low accuracy. Attached Figure Description

[0017] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the drawings in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the structure of a single crystal furnace according to an embodiment of this application is shown;

[0019] Figure 2 A schematic diagram of another single crystal furnace provided according to an embodiment of this application is shown;

[0020] Figure 3 A schematic flowchart of a crystal pulling method according to an embodiment of this application is shown;

[0021] Figure 4 A schematic diagram of the welding stage in a crystal pulling process according to an embodiment of this application is shown;

[0022] Figure 5 A schematic diagram of a shoulder formation stage in a crystal pulling process according to an embodiment of this application is shown;

[0023] Figure 6 A schematic diagram of the constant diameter stage in a crystal pulling process provided according to an embodiment of this application is shown.

[0024] The above figures include the following reference numerals:

[0025] 10. Furnace body sub-chamber; 11. Temperature measuring interface; 111. First temperature measuring interface; 112. Second temperature measuring interface; 20. Temperature measuring device; 21. First thermocouple; 211. First temperature measuring point; 212. First electrical coupling wire; 213. Second electrical coupling wire; 214. First insulation layer; 215. Second insulation layer; 22. Second thermocouple; 23. Outer sheath; 221. Second temperature measuring point; 30. Seed crystal; 31. Clamping end; 32. Through hole; 33. Growth end; 40. Melt; 50. Solid-liquid interface. Detailed Implementation

[0026] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0027] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0028] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0029] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0030] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0031] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0032] In the accompanying drawings corresponding to the embodiments of this application, the thickness and area of ​​the layers are enlarged for better understanding and ease of description. When describing a component (such as a layer, film, region, or substrate) on or on the surface of another component, the component may be "directly" located on the surface of the other component, or there may be a third component between the two components. Conversely, when describing a component on the surface of another component, or when another component is formed or disposed on the surface of a component, it indicates that there is no third component between the two components. Furthermore, when describing a component as being "generally" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a portion of the edge of the entire surface.

[0033] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included. Furthermore, when a component such as a layer, film, region, or plate is referred to as being "on / located" on another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may be present therein. Moreover, when a component such as a layer, film, region, or plate is "directly located" on another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it indicates that no other components are located therein.

[0034] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the term "part" is also intended to include the plural form unless the context clearly indicates otherwise. Components include layers, films, regions, or plates, etc.

[0035] As the background technology shows, temperature is the most fundamental and important parameter in the Czochralski method of crystal growth. Temperature is not only the driving force for silicon melting and melt crystallization, but also determines the crystal quality such as oxygen content and micro-defect density by affecting melt flow and crystal thermal stress.

[0036] The ratio of the temperature difference between two points to the distance between the two points, the temperature gradient, and the axial temperature gradient at the solid-liquid interface directly determine the upper limit of the crystallization rate that the solution can achieve. In addition, the ratio of the crystal growth rate to the axial temperature gradient at the interface (V / G) also determines the number and distribution of crystal defect sources—vacancy and interstitial atoms.

[0037] Regarding temperature, the current photovoltaic monocrystalline silicon industry generally uses CCD imaging to estimate temperature, but only estimates the temperature of the central region of the melt surface. As for temperature gradient, there is no effective method for measuring temperature gradient in existing technologies; typically, the temperature gradient inside the furnace is estimated through numerical calculations. That is, existing technologies use the grayscale value of the CCD image during welding (considered to be 1412℃) as a calibration value, and then estimate the temperature value corresponding to other grayscale values. The principle of obtaining temperature / temperature gradient in existing technologies is to abstract the actual growth furnace into a 2D axisymmetric structure, assign different physical properties to each geometric shape to represent actual materials such as crystals, melts, and soft felts, and discretize the geometric mesh. Then, using the finite volume or finite element method, partial differential equations for physicochemical processes such as flow, heat transfer, mass transfer, and phase transitions are solved on these meshes, and finally, the temperature gradient value is calculated using the obtained temperature information.

[0038] The existing technology of obtaining temperature information through CCD imaging has the following problems: 1. Too few measurement points, only the liquid surface temperature value can be obtained, while the temperature of important locations such as crystals / melts still cannot be obtained; 2. Low accuracy, the gray value of the image during fusion as the calibration value of 1412℃ itself has a large error, because the transition state from melting to crystallization corresponds to a temperature range rather than a certain value, and the relationship between temperature and liquid surface brightness is not strictly linear.

[0039] Furthermore, existing technologies for obtaining temperature / temperature gradient information through numerical simulation have the following problems: 1. High technical difficulty: It requires a foundation in numerical heat transfer, fluid mechanics, and other professional knowledge, as well as licensing of commercial software such as CGSim and Fluent, and the ability to operate the software in order to obtain information such as temperature gradients through numerical simulation; 2. Low reliability: The simplification of dimensions and physicochemical processes, and the lack of accurate high-temperature physical properties of various materials, greatly reduce the accuracy of numerical simulation. The results obtained can only reflect a certain trend, but cannot accurately reflect the actual situation.

[0040] To address the problem that temperature measurement in the prior art during crystal pulling is not only limited in number of measurement points but also has low accuracy, embodiments of this application provide a single crystal furnace and a crystal pulling method.

[0041] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0042] Figure 1 This is a schematic diagram of the structure of a single crystal furnace provided in an embodiment of this application, as shown below. Figure 1 As shown, the single crystal furnace includes: a furnace sub-chamber 10 with a temperature measuring interface 11; a temperature measuring device 20, the first end of which has a temperature measuring part, the first end of which extends from the clamping end 31 of the seed crystal 30 into the through hole 32 of the seed crystal 30 and extends out from the growth end 33 of the seed crystal 30, the second end of which is electrically connected to the temperature measuring interface via a signal line, the first end and the second end of which are opposite ends; wherein, the central axis of the through hole 32 is parallel to the central axis of the seed crystal 30.

[0043] In some embodiments, the aforementioned through hole is a central through hole, and the central axis of the through hole is the central axis of the seed crystal. During the crystal pulling process, the temperature measuring device and the seed crystal are located together inside the auxiliary chamber of the furnace body, and the temperature measuring device is electrically connected to the temperature measuring interface on the auxiliary chamber of the furnace body.

[0044] The temperature measuring device in the aforementioned single-crystal furnace moves upwards with the crystal growth, thereby measuring the temperature of the melt, solid-liquid interface, and within the crystal, and finally calculating the temperature gradient at different locations. In this embodiment, the temperature measuring device in the single-crystal furnace can directly measure the temperature within the crystal and melt. By arranging thermocouples in the through-hole of the seed crystal, the first end of the temperature measuring device extends from the growth end of the seed crystal and penetrates into the crystal growth environment, while the second end is electrically connected to the temperature measuring interface of the furnace sub-chamber, realizing real-time transmission of temperature data. As a direct-contact temperature measuring element, the thermocouple's temperature measurement results are not affected by image grayscale values, providing more accurate temperature readings compared to the indirect estimation of CCD imaging. Furthermore, the thermocouple can acquire multi-point temperature information during the crystal growth process, including the temperature of the melt, solid-liquid interface, and different locations within the crystal, thereby enabling the calculation of a more precise axial temperature gradient. Therefore, it significantly improves the accuracy and coverage of temperature measurement, providing more reliable data support for the growth control of single-crystal silicon, helping to optimize crystal growth rate, reduce crystal defects, and improve crystal quality. This improvement overcomes the technical difficulties and low reliability of temperature information acquisition in existing technologies, and promotes the progress of crystal growth technology in the photovoltaic monocrystalline silicon industry.

[0045] The single crystal furnace described in this application includes: a furnace sub-chamber with a temperature measurement interface; a temperature measurement device, the first end of which has a temperature measuring section, extending from the clamping end of the seed crystal into the through hole of the seed crystal and extending from the growth end of the seed crystal; the second end of which is electrically connected to the temperature measurement interface via a signal line, the first and second ends of which are opposite ends; wherein the central axis of the through hole is the central axis of the seed crystal. The solar cell provided by the embodiments of this application can at least improve the photoelectric conversion efficiency of the solar cell. This single crystal furnace obtains temperature and temperature gradient information through actual measurement by the temperature measurement device, which greatly improves the accuracy. It can also measure the temperature values ​​at different positions in the melt and on the central axis of the crystal during the actual crystal pulling process, providing an accurate data basis for seed crystal growth, and solving the problem that the temperature measurement in the crystal pulling process in the prior art is not only limited in the number of measurement points but also has low accuracy.

[0046] In some embodiments, the temperature measuring device includes multiple thermocouples, one end of each thermocouple passing through the through hole and extending from the growth end of the seed crystal. The end of each thermocouple extending from the growth end of the seed crystal forms a temperature measuring point, and the temperature measuring points of the multiple thermocouples form the temperature measuring part. There are multiple temperature measuring interfaces, and each of the multiple temperature measuring interfaces is arranged in a one-to-one correspondence with the multiple thermocouples. The end of each thermocouple away from the temperature measuring point is connected to the corresponding temperature measuring interface through a signal line. The temperature measuring points of the multiple thermocouples are distributed along the axial direction of the seed crystal.

[0047] The thermocouples mentioned above require materials that can withstand temperatures exceeding 1600°C for extended periods; the higher the temperature resistance, the better. Types S, R, B, or C can be selected. Type S thermocouples (platinum-rhodium 10-platinum): Type S thermocouples have a measurement range of -200°C to 1600°C, offering excellent accuracy and stability, and are commonly used in laboratories and applications requiring high-precision temperature measurement. Type R thermocouples (platinum-rhodium 13-platinum): Type R thermocouples have a similar measurement range to Type S, also -200°C to 1600°C, but their long-term operating temperature can reach 1800°C. Their performance is comparable to Type S, but they exhibit better thermoelectric properties at high temperatures. Type B thermocouples (platinum-rhodium 30-platinum-rhodium 6): Type B thermocouples have a measurement range of 0°C to 1800°C, with short-term use reaching 2000°C. They perform excellently in high-temperature environments and are commonly used for furnace temperature measurement and heat treatment of high-temperature materials. Type C thermocouples (Tungsten-Rhenium 5-Tungsten-Rhenium 26): Type C thermocouples are used for the highest temperature range, with a measurement range of -200°C to 2300°C, and up to 2600°C for short-term use. They exhibit excellent stability under extreme high-temperature conditions and are suitable for temperature measurement in high-temperature furnaces, combustion chambers, and other high-temperature environments.

[0048] The choice of different types of thermocouples depends primarily on the temperature range to be measured and environmental conditions, such as oxidizing, reducing, or inert atmospheres. In high-temperature environments such as single-crystal furnaces, thermocouples with a maximum measuring temperature exceeding 1800℃, such as Type B platinum-rhodium 30 or Type C tungsten-rhenium 5, are typically selected, offering better thermoelectric performance and stability.

[0049] In this embodiment, the temperature measuring device integrates multiple thermocouples. One end of each thermocouple passes through a through-hole in the seed crystal and extends from the growth end, forming its own temperature measuring point. This ensures accurate temperature monitoring at different depths during crystal growth. Multiple temperature measuring interfaces are also designed, matching the number of thermocouples. Signal lines connect the ends of each thermocouple to their corresponding temperature measuring interfaces, enabling real-time data transmission and processing. The temperature measuring points of the multiple thermocouples are evenly distributed along the axial direction of the seed crystal, increasing the coverage of temperature measurement and capturing subtle changes in the temperature gradient during crystal growth. As the crystal grows, the thermocouple positions adjust accordingly, dynamically acquiring temperature data at different growth stages. This provides crucial experimental evidence for optimizing the quality of single-crystal silicon materials, significantly improving measurement accuracy and data comprehensiveness. This helps to gain a deeper understanding of the thermodynamic behavior during crystal growth, guiding the optimization of process parameters and significantly improving the microstructure and performance of the crystal material. Furthermore, the distribution of multiple thermocouple measuring points along the axial direction of the seed crystal ensures continuous temperature measurement and accurate capture of the axial gradient. By adjusting the distance between thermocouples, such as setting it to 3-8 mm, more detailed temperature change curves can be obtained at different stages of crystal growth. This is crucial for studying the thermal environment during crystal growth and understanding the defect formation mechanism. It overcomes the limitations of CCD imaging temperature measurement and the uncertainties of numerical simulation, while also enabling direct measurement of the internal temperature field and temperature gradient of the crystal.

[0050] In some embodiments, such as Figure 2 As shown, the temperature measuring device 20 includes a first thermocouple 21 and a second thermocouple 22. The end of the first thermocouple 21 extending from the growth end 33 of the seed crystal 30 is a first temperature measuring point 211, and the end of the second thermocouple 22 extending from the growth end 33 of the seed crystal 30 is a second temperature measuring point 221. The distance between the first temperature measuring point 211 and the growth end 33 of the seed crystal 30 is greater than the distance between the second temperature measuring point 221 and the growth end 33 of the seed crystal 30. At least two temperature measuring interfaces 11 are included, including a first temperature measuring interface 111 and a second temperature measuring interface 112. The end of the first thermocouple 21 furthest from the first temperature measuring point 211 is connected to the first temperature measuring interface 111 via a signal line, and the end of the second thermocouple 22 furthest from the second temperature measuring point 221 is connected to the second temperature measuring interface 112 via a signal line.

[0051] The temperature gradient is calculated using the formula G = (T1 - T2) / L. 12 G represents the temperature gradient, T1 is the temperature measured at the first temperature measuring point, T2 is the temperature measured at the second temperature measuring point, and L... 12 This represents the axial distance between the first and second temperature measuring points. The axial distance between the first and second temperature measuring points is generally set to 3-8 mm. According to the temperature gradient calculation formula, at least two temperature points are required to calculate the temperature gradient value. Therefore, at least two thermocouples are used to measure the temperature at two points simultaneously (avoiding interference from time fluctuations). The axial distance between the first and second temperature measuring points needs to ensure a certain temperature difference between the two points; therefore, it cannot be too close, but it must also avoid being too far apart and missing the temperature gradient at crucial points.

[0052] In this embodiment, the temperature measuring device, through the configuration of a first thermocouple and a second thermocouple, achieves precise measurement of the axial temperature of the melt and crystal within the single crystal furnace. The first temperature measuring point of the first thermocouple and the second temperature measuring point of the second thermocouple are located at different heights; the first temperature measuring point is farther from the seed crystal growth end, while the second temperature measuring point is relatively closer. This design allows for continuous monitoring of temperature changes on both sides of the solid-liquid interface at different stages of single crystal growth. At least two temperature measuring interfaces are designed, including a first temperature measuring interface and a second temperature measuring interface, which are connected to the first and second thermocouples respectively via signal lines, ensuring that the two sets of temperature data can be independently acquired and processed. In the early stages of crystal growth, when the seed crystal is immersed in the melt, both the first and second temperature measuring points are within the melt, enabling real-time measurement of the temperature distribution inside the melt. As the crystal continues to grow, the second temperature measuring point will first contact the solid-liquid interface and enter the crystal interior, thus beginning simultaneous measurement of the temperature of both the melt and the crystal, until the first temperature measuring point also enters the crystal. During this process, the measured data can be used to accurately calculate the axial temperature gradient at the interface, providing direct and reliable information for optimizing single-crystal silicon growth conditions and improving crystal quality. Furthermore, the thermocouples are made of type B platinum-rhodium 30 or type C tungsten-rhenium 5 materials, capable of withstanding extreme high temperatures up to 1800℃, ensuring the stability and accuracy of the measurements. The sheaths are made of high-purity alumina or high-purity silicon dioxide, further enhancing the heat resistance and corrosion resistance of the temperature measuring device, ensuring the normal operation of the thermocouples in harsh environments.

[0053] In some embodiments, such as Figure 2As shown, each of the above thermocouples includes: a first electrical coupling wire 212, a second electrical coupling wire 213, a first insulating layer 214, and a second insulating layer 215. The end of the first electrical coupling wire 212 that is in contact with the second electrical coupling wire 213 is the temperature measuring point. The first insulating layer 214 is wrapped around the first electrical coupling wire 212 and the second electrical coupling wire 213. The second insulating layer 215 is located between the first electrical coupling wire 212 and the second electrical coupling wire 213.

[0054] The diameter of the electrocoupler wire needs to be set by comprehensively considering both the measurement response speed and mechanical strength. Specifically, the thinner the electrocoupler wire, the faster the measurement response speed; the thicker the electrocoupler wire, the higher the mechanical strength. Therefore, the diameter of the electrocoupler wire needs to simultaneously meet the requirements of response speed and mechanical strength. In some embodiments, the diameters of the first and second electrocoupler wires can be set to 0.4-0.6 mm, the thicknesses of the first and second insulating layers can be set to 0.3-0.5 mm, the diameter of a single thermocouple is generally 2.5-3 mm, and the outer diameter of the sheath accommodating two thermocouples can be set to 6-8 mm. The conventional seed crystal size is approximately 230 mm in length, the diameter of the thicker end of the seed crystal's clamping end is approximately 28 mm, the diameter of the thinner end of the seed crystal's growth end is approximately 18 mm, and the diameter of the through hole drilled along the central axis of the seed crystal is approximately 7-8 mm. The sheath containing the two thermocouples is then passed through the through hole. Additionally, the thermocouple is approximately 4-5 meters long. The thermocouple measuring end extends about 60-80 mm beyond the lower growth end of the seed crystal. The other end of the thermocouple passes through the upper clamping end of the seed crystal and continues through the clamp, finally exiting from the flange with the thermocouple interface in the furnace sub-chamber to the temperature measuring instrument. The second insulating layer between the thermocouple wires is made of alumina-resistant ceramic. Alumina ceramic provides electrical signal insulation and is heat-resistant, hence its use as the insulating layer between the thermocouple wires.

[0055] In this embodiment, the temperature measuring device includes a dual thermocouple temperature measuring system. Each thermocouple consists of a first thermocouple wire and a second thermocouple wire, with their contact ends serving as the actual temperature measuring point to accurately capture temperature information. A first insulating layer covers the outside of the thermocouple wires, ensuring electrical insulation while resisting oxidation under high-temperature environments. The second insulating layer is placed between the two thermocouple wires, enhancing the overall stability and temperature measuring accuracy of the device. This design allows the temperature measuring point to move axially during crystal growth, thereby enabling continuous temperature measurement at different depths of the melt and crystal within the single-crystal furnace. By accurately measuring the temperature at the bottom of the melt, the solid-liquid interface, and inside the crystal, key temperature gradient parameters can be calculated, which is crucial for optimizing crystal growth conditions and reducing crystal defects. The selection and structural design of the thermocouples in this embodiment, especially the configuration of the insulating layer, significantly enhance the durability and safety of the temperature measuring device, enabling it to operate stably in extreme high-temperature environments and obtain accurate temperature data. This direct measurement method, rather than indirect estimation, greatly improves the accuracy and practicality of temperature and temperature gradient measurements, providing strong support for the quality control of Cz single-crystal silicon materials. In addition, the axial distance design of the thermocouples not only facilitates installation but also ensures that the measurement range covers the critical areas of crystal growth.

[0056] In some embodiments, such as Figure 2 As shown, the temperature measuring device also includes an outer sheath 23, which is used to completely enclose the plurality of thermocouples.

[0057] The outer sheath is made of high-purity alumina or high-purity silicon dioxide. Because the temperature measuring end needs to be inserted into the molten silicon, the sheath must minimize contamination of the molten silicon and be resistant to high temperatures. Silicon dioxide is the same material as the crucible and has been proven in practice, so high-purity silicon dioxide is selected for the sheath.

[0058] In this embodiment, the temperature measuring device also includes an outer sheath for completely enclosing multiple thermocouples. The choice of the outer sheath is crucial; its material should possess high purity and excellent high-temperature stability, such as high-purity alumina or high-purity silicon dioxide, to ensure the accuracy and safety of the thermocouples under extreme high-temperature environments. This design not only protects the thermocouples from harsh environments but also ensures precise alignment of the measuring point with the central axis of the crystal / melt, thereby improving the accuracy of temperature measurement. Furthermore, the sheath reduces heat exchange between the thermocouples and the surrounding medium, minimizing interference from external factors and ensuring more reliable data. During crystal growth, as the thermocouples rise with the crystal, the outer sheath 23 maintains the overall structural stability of the device, ensuring that the measuring point remains unaffected by the crystal's own weight, even when the crystal has grown to several meters in length, continuously providing accurate temperature information. Therefore, the outer sheath not only enhances the practicality of the temperature measuring device but also strengthens its applicability and measurement accuracy during single-crystal silicon growth.

[0059] In some embodiments, the single crystal furnace further includes an adhesive layer located between the outer sheath and the sidewall of the through hole.

[0060] In this embodiment, an adhesive layer is added to the temperature measuring device inside the single crystal furnace, located between the outer sheath and the sidewall of the through hole. The introduction of the adhesive layer aims to enhance the connection stability between the temperature measuring device and the seed crystal, ensuring that the thermocouple can be accurately positioned and follow the crystal's lifting motion during crystal growth, thereby obtaining more accurate temperature measurements and temperature gradient information. Through this design, the adhesive layer not only fills the gap between the through hole sidewall and the outer sheath, enhancing the overall structure's sealing and durability, but also effectively reduces heat loss during heat conduction, improving the sensitivity and accuracy of temperature measurement. This improvement is significant for in-depth research into crystal growth mechanisms, optimizing growth conditions, and improving crystal quality, especially in the modern photovoltaic industry pursuing higher efficiency and lower defect crystal materials, providing more reliable measured data support for adjusting process parameters. Furthermore, the adhesive layer design considers the matching of the materials' thermal expansion coefficients, avoiding loosening or damage to the device due to differences in the thermal expansion coefficients of different materials, ensuring the stability and safety of the temperature measuring device throughout the entire growth cycle.

[0061] In some embodiments, the single crystal furnace further includes a temperature measuring instrument, which is electrically connected to the temperature measuring device via the temperature measuring interface, and is used to convert the electrical signal of the temperature measuring device into a digital signal.

[0062] In this embodiment, the device for measuring the axial temperature of the melt / crystal within the single-crystal furnace is combined with a temperature measuring instrument to form a complete temperature data acquisition system. The temperature measuring device includes two high-precision thermocouples, which are precisely arranged and electrically connected to an external temperature measuring instrument via thermocouple interfaces. The temperature measuring instrument is responsible for converting the continuous electrical signal from the temperature measuring device into a digital signal that is easy to analyze and process, thereby monitoring and recording the temperature changes at different axial positions during crystal growth in real time. This design overcomes the limitation of traditional CCD imaging, which can only estimate the liquid surface temperature, and provides more comprehensive and accurate temperature gradient information, which has a significant promoting effect on optimizing the growth conditions of Czochralski single-crystal silicon and improving crystal quality. Through direct measurement, the temperature dynamics during the initial stage of crystal growth, the shoulder formation stage, and the subsequent cooling process can be obtained, enabling the preparation of higher-quality single-crystal silicon materials.

[0063] This embodiment also provides a crystal pulling method. Figure 3 This is a flowchart of a crystal pulling method according to an embodiment of this application. For example... Figure 3 As shown, it includes the following steps:

[0064] Step S101: Crystal pulling is performed using any of the single crystal furnaces described above;

[0065] Step S102: During the crystal pulling process, the temperature measurement device of the single crystal furnace is used to detect the temperature data in real time during the crystal pulling process, and the crystal pulling parameters are determined based on the temperature data. The crystal pulling process includes the fusion stage, the crystal pulling stage, the shoulder forming stage, the shoulder turning stage, the equal diameter stage, and the finishing stage. The temperature data includes at least the melt temperature, the solid-liquid interface temperature, and the crystal temperature. The crystal pulling parameters include at least the crystal rotation speed, the crucible rotation speed, and the crystal pulling speed.

[0066] The aforementioned crystal pulling method first employs any of the aforementioned single-crystal furnaces for crystal pulling. Then, during the crystal pulling process, a temperature measuring device within the single-crystal furnace is used to monitor the temperature data in real time. Based on this temperature data, crystal pulling parameters are determined for the fusion stage, seeding stage, shoulder formation stage, shoulder turning stage, equal diameter stage, and finishing stage. This method obtains temperature and temperature gradient information through actual measurement using a temperature measuring device, significantly improving accuracy. Furthermore, it can measure temperature values ​​at different locations within the melt and along the crystal's central axis during the actual crystal pulling process, providing an accurate data foundation for seed crystal growth. Based on the temperature data during the crystal pulling process, crystal pulling parameters such as crystal rotation speed, crucible rotation speed, and crystal pulling speed can be accurately determined, solving the problem in existing technologies where temperature measurements during crystal pulling are limited in number and have low accuracy.

[0067] The crystal pulling method provided in this application primarily utilizes a temperature measuring device containing two thermocouples arranged in a single crystal furnace to monitor temperature data in real time during the crystal pulling process. This method continuously acquires key temperature information such as melt temperature, solid-liquid interface temperature, and crystal temperature at different stages of crystal pulling, such as fusion, crystal introduction, shoulder formation, shoulder rotation, equal diameter stage, and finishing stage. Based on this temperature data, crystal pulling parameters such as crystal rotation speed, crucible rotation speed, and crystal pulling speed can be precisely adjusted to optimize crystal growth conditions. This significantly improves the accuracy of temperature control and the consistency of crystal growth, greatly enhancing the understanding and control of the core parameter of temperature gradient during crystal growth. This contributes to further improving the quality and performance of the crystal, especially demonstrating significant advantages in suppressing crystal defect formation and optimizing crystal purity.

[0068] In some embodiments, the temperature measuring device includes a first thermocouple and a second thermocouple. The first thermocouple extends from the growth end of the seed crystal as a first temperature measuring point, and the second thermocouple extends from the growth end of the seed crystal as a second temperature measuring point. The distance between the first temperature measuring point and the growth end of the seed crystal is greater than the distance between the second temperature measuring point and the growth end of the seed crystal. During the crystal pulling process, the temperature measuring device of the single crystal furnace is used to monitor the temperature data in real time, and the crystal pulling parameters are determined based on the temperature data, including the following steps:

[0069] Step S201: During the crystal pulling process, the temperature data of the first temperature measuring point and the temperature data of the second temperature measuring point are obtained to obtain the first temperature data and the second temperature data respectively.

[0070] Step S202: Obtain the distance between the temperature measuring points, and determine the difference between the first temperature data and the second temperature data as the temperature difference value. The distance between the temperature measuring points is the distance between the first temperature measuring point and the second temperature measuring point along the central axis of the seed crystal.

[0071] Step S203: The ratio between the temperature difference and the distance between the temperature measuring points is determined as the temperature gradient, and the crystal pulling parameters of the crystal pulling process are determined based on the temperature gradient.

[0072] In this embodiment, a temperature gradient measurement device for the Czochralski method of single-crystal silicon pulling process is proposed. This device consists of a first thermocouple and a second thermocouple, respectively positioned at different axial positions on the seed crystal growth end, i.e., a first temperature measuring point and a second temperature measuring point. The first temperature measuring point is located relatively far from the seed crystal growth end, while the second temperature measuring point is located closer to the seed crystal growth end. During the crystal pulling process, as the pulling progresses, the device can monitor and record the temperature data of the first and second temperature measuring points in real time. By collecting the temperature data and combining it with the axial distance between the two points, the axial temperature gradient at the solid-liquid interface can be accurately calculated, providing more reliable and detailed temperature information. This significantly helps in optimizing crystal pulling parameters, such as power, pulling speed, and rotation speed, thereby improving the crystal quality of single-crystal silicon and reducing oxygen content and micro-defect density. Furthermore, since the device can measure the temperature changes at different locations during the cooling process of the crystal, it can also provide strong data support for studying the thermal stress distribution inside the crystal and further improving the performance of crystalline silicon materials.

[0073] In some embodiments, during the welding stage, the first temperature data is the first melt temperature, the second temperature data is the second melt temperature, and the temperature gradient is the melt temperature gradient. Determining the crystal pulling parameters based on the temperature gradient includes the following steps:

[0074] Step S2031: Determine the melt flowability parameters based on the above melt temperature gradient;

[0075] Step S2032: Based on the above melt flowability parameters, determine the crystal rotation speed, the crucible rotation speed, the heater length, and the heater position.

[0076] Among them, the temperature distribution information in the melt can help determine the strength of the melt flow, and thus assist in judging the rationality of processes such as crystal and crucible rotation speed, as well as the thermal field structure such as heater length and position, providing an important basis for growth process and thermal field design.

[0077] In this embodiment, when the first temperature data is the first melt temperature, the second temperature data is the second melt temperature, and the temperature gradient is the melt temperature gradient, the temperature measuring device can accurately capture the temperature changes within the melt during the welding stage. This design allows for the fine-tuning and optimization of crystal pulling parameters based on the melt temperature gradient. Specifically, this includes determining the melt flowability parameters based on the melt temperature gradient, as these parameters directly affect the heat transfer efficiency and crystal quality during crystal growth. Subsequently, based on the optimized flowability parameters, the crystal rotation speed, crucible rotation speed, heater length, and heater position can be scientifically adjusted to achieve the ideal crystal growth rate and quality. This method enables precise temperature control during crystal growth, effectively suppressing defects such as oxygen content and micro-defect density, and significantly improving the overall performance and consistency of the crystal material.

[0078] In some embodiments, during the shoulder-forming stage, the first temperature data is a first solid-liquid interface temperature, the second temperature data is a second solid-liquid interface temperature, and the temperature gradient is a solid-liquid interface temperature gradient. Determining the crystal pulling parameters based on the temperature gradient includes: determining the crystal pulling speed based on the solid-liquid interface temperature gradient, such that the difference between the crystal growth parameter ratio and a preset ratio is within a preset range, wherein the growth parameter ratio is the ratio of the crystal growth speed to the temperature gradient, and the crystal pulling speed is directly proportional to the solid-liquid interface temperature gradient.

[0079] Among them, the temperature data of the solid-liquid interface can be used to directly determine whether the timing of seed crystal fusion is appropriate; the temperature gradient of the solid-liquid interface can be used to determine a suitable pulling rate, so that the V / G value is close to the critical V / G value, thereby making the number of vacancies and interstitial atoms equal and thus completely recombine and annihilate, ultimately obtaining a high-quality crystal. V is the crystal growth rate, and G is the temperature gradient.

[0080] In this embodiment, when the first temperature data is the first solid-liquid interface temperature and the second temperature data is the second solid-liquid interface temperature, the temperature gradient is defined as the solid-liquid interface temperature gradient. By monitoring the solid-liquid interface temperature gradient in real time, the crystal pulling speed can be dynamically adjusted to ensure that the deviation between the crystal growth parameter ratio and the preset ratio is controlled within a preset range. This ratio is the ratio of the crystal growth speed to the solid-liquid interface temperature gradient, where the crystal pulling speed and the solid-liquid interface temperature gradient are directly proportional. This allows for precise control of crystal growth conditions, optimization of the generation and distribution of point defects within the crystal, and further improvement of the quality of the crystal material. Simultaneously, the adjustment of the crystal growth speed directly responds to changes in the solid-liquid interface temperature gradient, achieving precise management of the crystal growth process, which helps reduce defects in crystal growth and improve the yield.

[0081] In some embodiments, during the constant diameter stage, the temperature data includes the crystal temperature. Determining the crystal pulling parameters based on the temperature data includes determining the cooling parameters of the crystal based on the crystal temperature. The cooling parameters include the installation position of the cooling device and the cooling temperature of the cooling device. The crystal temperature and the cooling temperature of the cooling device have a corresponding relationship.

[0082] Among them, mastering the temperature data when the crystal rod arrives at each position in the furnace can serve as an important basis for optimizing the crystal rod cooling process. For example, the temperature range of 800-600℃ during the crystal cooling process is the period of oxygen precipitation nucleus formation. Air cooling or water cooling devices can be added at the corresponding positions to shorten the residence time of the crystal rod in the 800-600℃ temperature range, thereby inhibiting the formation of oxygen precipitation nuclei and improving crystal quality.

[0083] In this embodiment, when the single crystal furnace enters the constant diameter stage, the thermocouples in the temperature measuring device continuously monitor the temperature changes inside the crystal, collecting detailed crystal temperature data. Based on this temperature data, the crystal pulling parameters during the crystal pulling process can be precisely adjusted, especially the crystal cooling parameters, including but not limited to the installation position and cooling temperature of the cooling device. There is a direct correlation between the crystal temperature and the cooling temperature of the cooling device. By monitoring the crystal temperature in real time, the cooling strategy can be dynamically adjusted to ensure that the crystal obtains optimal cooling conditions during growth, thereby effectively controlling the thermal stress of the crystal, reducing the generation of micro-defects, improving the overall quality of the crystal, providing strong support for the research and development of crystal materials, helping to deepen the understanding of crystal growth mechanisms, and promoting the advancement of single crystal silicon material preparation technology.

[0084] In some alternative embodiments, such as Figure 4 , Figure 5 and Figure 6As shown, during the initial fusion, the growth end of the seed crystal 30 is submerged in the melt 40 by approximately 404-8 mm, and the temperature measuring device 20 (i.e., the thermocouple) is submerged in the melt 40 by approximately 64-88 mm. At this point, the temperature and temperature gradient distribution along the central axis within the melt 40 can be measured. As the crystal grows, the thermocouple measuring end gradually moves from the melt through the solid-liquid interface 50 into the crystal. It is foreseeable that at some point during the shoulder formation stage, temperature measuring point B will enter the crystal while temperature measuring point A will still be in the melt. At this time, the temperature measuring device can simultaneously measure the temperature of the melt 40 and the crystal along the axis, thereby obtaining the axial temperature gradient at the solid-liquid interface 50. Once the temperature measuring point has completely entered the crystal, the temperature at different locations during the cooling process after the crystal leaves the liquid surface can be recorded. For example, the crystal temperature is ~1400℃ near the liquid surface, drops to 1000℃~1300℃ inside the water-cooled jacket, and drops to 500~700℃ at the throat.

[0085] It is worth noting that the above embodiments are intended to obtain temperature information that is difficult to obtain in actual production, rather than to pull high-quality crystal rods. Therefore, the raw and auxiliary materials (silicon, crucible, soft felt, etc.) and crystal pulling process parameters (power, crystal / crate rotation speed, pulling speed, etc.) are consistent with those in actual production, but are not subject to other constraints such as dislocation-free and low-defect conditions. Thus, equal-diameter welding is used during fusion instead of diameter-reduction welding, thereby ensuring crystal strength. Furthermore, the crystal can be pulled to 2-3 meters before being stopped, ensuring that the seed crystal portion is sufficient to support the entire crystal weight.

[0086] Furthermore, existing methods in the photovoltaic field that indirectly estimate liquid surface temperature using CCD imaging not only lack the theoretical basis for accurate calculation but also only obtain the temperature of a portion of the liquid surface. While numerical simulations for calculating temperature and temperature gradients are technically challenging and only provide trends rather than reliable guidance, the single-crystal furnace and crystal pulling method proposed in this embodiment significantly improve accuracy by obtaining temperature and temperature gradient information through actual thermocouple measurements. Moreover, thanks to the device design, temperature values ​​at different locations within the melt and along the crystal's central axis can be measured during the actual crystal pulling process.

[0087] In other embodiments, a system for actively controlling the temperature gradient is also included, such as using heating elements or heat exchange devices to dynamically adjust the temperature distribution near the crystal growth interface. By precisely controlling the temperature gradient at the solid-liquid interface, the V / G value can be optimized without changing the crystal growth rate, thereby improving crystal quality. An intelligent temperature gradient control system is developed by combining machine learning techniques. This system can predict and adjust the temperature gradient at the solid-liquid interface based on various sensor data during crystal growth (including but not limited to temperature, pressure, rotational speed, etc.) to optimize the V / G value. Through continuous learning and iteration, the system can automatically adapt to different growth conditions, improving the consistency and repeatability of crystal growth.

[0088] In other embodiments, the temperature measuring device can be integrated with the automated control system for crystal growth to achieve real-time data feedback and control adjustments. For example, when the temperature gradient detected during crystal growth deviates from a preset value, the automated system can instantly adjust the crystal pulling speed or heating power to restore the optimal V / G value, thereby ensuring that the crystal quality is not affected.

[0089] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A single crystal furnace, characterized in that, The single crystal furnace includes: The auxiliary chamber of the furnace body has a temperature measurement interface; A temperature measuring device, wherein the first end of the temperature measuring device has a temperature measuring part, the first end of the temperature measuring device extends from the clamping end of the seed crystal into the central through hole of the seed crystal and extends out from the growth end of the seed crystal, and the second end of the temperature measuring device is electrically connected to the temperature measuring interface through a signal line, wherein the first end and the second end of the temperature measuring device are opposite ends; wherein, the central axis of the through hole is parallel to the central axis of the seed crystal.

2. The single crystal furnace according to claim 1, characterized in that, The temperature measuring device includes multiple thermocouples, one end of each thermocouple passing through the through hole and extending from the growth end of the seed crystal. The end of each thermocouple extending from the growth end of the seed crystal forms a temperature measuring point, and the temperature measuring points of the multiple thermocouples form the temperature measuring section. There are multiple temperature measuring interfaces, and each of the multiple temperature measuring interfaces is arranged in a one-to-one correspondence with the multiple thermocouples. The end of each thermocouple away from the temperature measuring point is connected to the corresponding temperature measuring interface through a signal line. The temperature measuring points of the multiple thermocouples are distributed along the axial direction of the seed crystal.

3. The single crystal furnace according to claim 1, characterized in that, The temperature measuring device includes a first thermocouple and a second thermocouple. The end of the first thermocouple extending from the growth end of the seed crystal is a first temperature measuring point, and the end of the second thermocouple extending from the growth end of the seed crystal is a second temperature measuring point. The distance between the first temperature measuring point and the growth end of the seed crystal is greater than the distance between the second temperature measuring point and the growth end of the seed crystal. The device includes at least two temperature measuring interfaces, each including a first temperature measuring interface and a second temperature measuring interface. The end of the first thermocouple furthest from the first temperature measuring point is connected to the first temperature measuring interface via a signal line, and the end of the second thermocouple furthest from the second temperature measuring point is connected to the second temperature measuring interface via a signal line.

4. The single crystal furnace according to claim 2, characterized in that, Each thermocouple includes: a first coupling wire, a second coupling wire, a first insulating layer, and a second insulating layer. The end of the first coupling wire that contacts the second coupling wire is the temperature measuring point. The first insulating layer is wrapped around the first coupling wire and the second coupling wire, and the second insulating layer is located between the first coupling wire and the second coupling wire.

5. The single crystal furnace according to claim 2, characterized in that, The temperature measuring device also includes an outer sheath, which is used to completely enclose the plurality of thermocouples.

6. The single crystal furnace according to claim 5, characterized in that, The single crystal furnace also includes: An adhesive layer is located between the outer sheath and the sidewall of the through hole.

7. The single crystal furnace according to claim 1, characterized in that, The single crystal furnace also includes: A temperature measuring instrument, which is electrically connected to the temperature measuring device through the temperature measuring interface, is used to convert the electrical signal of the temperature measuring device into a digital signal.

8. A crystal pulling method, characterized in that, include: Crystal pulling is performed using the single crystal furnace described in any one of claims 1 to 7; During the crystal pulling process, the temperature measurement device of the single crystal furnace is used to detect the temperature data in real time, and the crystal pulling parameters are determined based on the temperature data. The crystal pulling process includes a fusion stage, a crystal pulling stage, a shoulder forming stage, a shoulder turning stage, a constant diameter stage, and a finishing stage. The temperature data includes at least the melt temperature, the solid-liquid interface temperature, and the crystal temperature. The crystal pulling parameters include at least the crystal rotation speed, the crucible rotation speed, and the crystal pulling speed.

9. The crystal pulling method according to claim 8, characterized in that, The temperature measuring device includes a first thermocouple and a second thermocouple. The end of the first thermocouple extending from the growth end of the seed crystal is a first temperature measuring point, and the end of the second thermocouple extending from the growth end of the seed crystal is a second temperature measuring point. The distance between the first temperature measuring point and the growth end of the seed crystal is greater than the distance between the second temperature measuring point and the growth end of the seed crystal. During the crystal pulling process, the temperature measuring device of the single crystal furnace is used to monitor the temperature data in real time, and the crystal pulling parameters are determined based on the temperature data, including: During the crystal pulling process, temperature data from the first temperature measuring point and temperature data from the second temperature measuring point are acquired to obtain first temperature data and second temperature data, respectively. The distance between the temperature measuring points is obtained, and the difference between the first temperature data and the second temperature data is determined as the temperature difference value. The distance between the temperature measuring points is the distance between the first temperature measuring point and the second temperature measuring point along the central axis of the seed crystal. The ratio between the temperature difference and the distance between the temperature measuring points is determined as the temperature gradient, and the crystal pulling parameters of the crystal pulling process are determined based on the temperature gradient.

10. The crystal pulling method according to claim 9, characterized in that, In the welding stage, the first temperature data is the first melt temperature, the second temperature data is the second melt temperature, the temperature gradient is the melt temperature gradient, and the crystal pulling parameters of the crystal pulling process are determined based on the temperature gradient, including: The melt flowability parameters are determined based on the melt temperature gradient. Based on the melt's fluidity parameters, the crystal rotation speed, the crucible rotation speed, the heater length, and the heater position are determined.

11. The crystal pulling method according to claim 9, characterized in that, In the shoulder-forming stage, the first temperature data is the first solid-liquid interface temperature, the second temperature data is the second solid-liquid interface temperature, and the temperature gradient is the solid-liquid interface temperature gradient. The crystal pulling parameters for the crystal pulling process are determined based on the temperature gradient, including: The crystal pulling speed is determined based on the solid-liquid interface temperature gradient, so that the difference between the crystal growth parameter ratio and the preset ratio is within a preset range. The growth parameter ratio is the ratio of the crystal growth speed to the temperature gradient, and the crystal pulling speed is directly proportional to the solid-liquid interface temperature gradient.

12. The crystal pulling method according to claim 8, characterized in that, In the constant diameter stage, the temperature data includes the crystal temperature, and the crystal pulling parameters for the crystal pulling process are determined based on the temperature data, including: The cooling parameters of the crystal are determined based on the crystal temperature. The cooling parameters include the installation position of the cooling device for the crystal and the cooling temperature of the cooling device. The crystal temperature and the cooling temperature of the cooling device have a corresponding relationship.

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