Single crystal furnace, preparation method of single crystal silicon rod and silicon wafer

Abstract

The invention relates to the technical field of photovoltaics, in particular to a single crystal furnace, a preparation method of a single crystal silicon rod and a silicon wafer. The single crystal furnace comprises a guide cylinder and a crucible, wherein the guide cylinder is positioned on the top side of the crucible; the adjusting mechanism is provided with a first adjusting part and a second adjusting part, one end of the first adjusting part is rotatably connected to the outer side wall of the bottom of the guide cylinder, and the other end of the first adjusting part is rotatably connected to the second adjusting part; the second adjusting part can move in the preset direction, and the preset direction is parallel to the direction from the top side of the guide cylinder to the bottom side of the guide cylinder. By controlling the second adjusting piece to move, the first adjusting piece can be driven to rotate, so that the form of a gas channel between the guide cylinder and the crucible is adjusted, the gas flow distribution in the furnace is optimized, the quality of a prepared monocrystalline silicon rod is improved, and the resistivity measurement accuracy is further improved.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a single crystal furnace, a method for preparing single crystal silicon rods, and silicon wafers. Background Technology

[0002] The Czochralski method is a major technology for the preparation of monocrystalline silicon and is widely used in the photovoltaic field. Resistivity, as a core parameter characterizing the electrical properties of monocrystalline silicon, directly determines the effectiveness of material performance evaluation and the reliability of end devices through its measurement accuracy. However, during the Czochralski growth of monocrystalline silicon, resistivity measurements are prone to distortion, resulting in a need to improve the quality of the pulled crystals. Summary of the Invention

[0003] Therefore, it is necessary to provide a single crystal furnace, a method for preparing single crystal silicon rods, and silicon wafers to improve the accuracy of resistivity measurement, thereby improving the quality of crystal pulling.

[0004] According to one aspect of this application, an embodiment of this application provides a single crystal furnace, including a flow guide tube, a crucible, and an adjustment mechanism.

[0005] The flow guide tube is located on the top side of the crucible.

[0006] The adjustment mechanism includes a first adjustment member and a second adjustment member. One end of the first adjustment member is rotatably connected to the outer side wall of the bottom of the guide tube, and the other end of the first adjustment member is rotatably connected to the second adjustment member. The second adjustment member is configured to move relative to the guide tube in a preset direction, and the preset direction is parallel to the direction from the top side of the guide tube to the bottom side of the guide tube.

[0007] In one embodiment, the first adjusting member has a first surface disposed toward the guide tube, the shape of the first surface being adapted to the shape of the outer wall of the guide tube.

[0008] In one embodiment, the adjusting mechanism further includes a third adjusting member;

[0009] One end of the third adjusting member is rotatably connected to the first adjusting member, and the other end of the third adjusting member is rotatably connected to the second adjusting member.

[0010] In one embodiment, the outer wall of the bottom of the guide tube includes an inclined section;

[0011] The first adjusting element is rotatably mounted on the inclined section.

[0012] In one embodiment, the inclined segment has a first end close to the crucible and a second end away from the crucible;

[0013] The angle between the direction from the first end to the second end and the preset direction is the first angle.

[0014] The direction of the first adjusting member connecting to the guide tube is [0°, 45°] and the angle between the direction of the first adjusting member connecting to the second adjusting member and the direction of the first end pointing to the second end is [0°, 45°].

[0015] In one embodiment, the first adjusting member is connected to one end of the guide tube, and the direction pointing to the first adjusting member is connected to one end of the second adjusting member, and the angle range between the first adjusting member and the preset direction is [45°, 90°].

[0016] According to another aspect of this application, embodiments of this application provide a method for preparing a single-crystal silicon rod. Using the aforementioned single-crystal furnace, the method for preparing the single-crystal silicon rod includes:

[0017] During the crystal pulling process, the position of the second adjusting element is controlled to adjust the position of the first adjusting element relative to the guide tube.

[0018] In one embodiment, during the crystal pulling process, controlling the second adjusting member to move along a preset direction to adjust the position of the first adjusting member relative to the guide tube includes:

[0019] During the shoulder-laying process, the second adjusting component is controlled to be in the first position, while the first adjusting component is kept in the second position; wherein, the end of the first adjusting component connected to the guide tube points in the direction of the end of the first adjusting component connected to the second adjusting component, and the angle formed with the preset direction is the preset angle; the first adjusting component is in the second position, and the preset angle is the initial angle;

[0020] During the equal diameter growth process, the second adjusting member is controlled to move along a preset direction, so that the preset angle decreases from the initial angle to 0° and remains unchanged until the equal diameter growth process ends.

[0021] In one embodiment, the initial angle ranges from [75°, 90°], and during the constant diameter growth process, the preset angle is reduced to 0° at a rate of 1° every 10 to 25 minutes.

[0022] In one embodiment, the method for preparing a single-crystal silicon rod further includes:

[0023] During the constant diameter growth process, the argon flow rate in the single crystal furnace is reduced.

[0024] In one embodiment, reducing the argon flow rate in the single crystal furnace includes a first flow reduction stage, a second flow reduction stage, and a third flow reduction stage performed sequentially.

[0025] The argon flow rate in the first flow reduction stage is greater than that in the second flow reduction stage, and the argon flow rate in the second flow reduction stage is greater than that in the third flow reduction stage.

[0026] In one embodiment, the method for preparing a single-crystal silicon rod further includes:

[0027] During constant diameter growth, reduce the furnace pressure inside the single crystal furnace; or...

[0028] During the constant diameter growth process, the furnace pressure is kept constant.

[0029] In one embodiment, reducing the furnace pressure within the single crystal furnace includes a first pressure reduction stage and a second pressure reduction stage performed sequentially.

[0030] In one embodiment, the method for preparing a single-crystal silicon rod further includes:

[0031] During the cooling process, the second adjusting component is controlled to move along a preset direction to adjust the preset angle to the initial angle.

[0032] According to another aspect of this application, an embodiment of this application provides a silicon wafer cut from a single-crystal silicon rod prepared by a method for preparing a single-crystal silicon rod.

[0033] This application provides a single-crystal furnace, a method for preparing single-crystal silicon rods, and silicon wafers. The single-crystal furnace includes a flow guide tube and a crucible, with the flow guide tube located on the top side of the crucible. It also includes an adjustment mechanism with a first adjustment member and a second adjustment member. One end of the first adjustment member is rotatably connected to the outer wall of the bottom of the flow guide tube, and the other end is rotatably connected to the second adjustment member. The second adjustment member can move along a preset direction, which is parallel to the direction from the top side of the flow guide tube to the bottom side. By controlling the movement of the second adjustment member, the first adjustment member can be rotated, thereby adjusting the gas channel morphology between the flow guide tube and the crucible, optimizing the gas flow distribution within the furnace, improving the quality of the prepared single-crystal silicon rod, and thus improving the accuracy of resistivity measurement of the single-crystal silicon rod. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a single crystal furnace in a working state, provided for some embodiments of this application.

[0035] Figure 2 This is a schematic diagram of the gas flow direction inside a single crystal furnace in a working state, provided for some embodiments of this application.

[0036] Figure 3 This is a schematic diagram of the structure of a single crystal furnace in another working state, as provided in some embodiments of this application.

[0037] Figure 4 This is a schematic diagram of the gas flow direction inside a single crystal furnace in another operating state, provided for some embodiments of this application.

[0038] Figure 5 This is a structural schematic diagram of a single crystal furnace in another working state, provided in some embodiments of this application.

[0039] Figure 6 This is a process flow diagram of a method for preparing a single-crystal silicon rod provided for some embodiments of this application.

[0040] Figure 7 A process flow diagram of another method for preparing a single-crystal silicon rod provided for some embodiments of this application.

[0041] Figure 8 This is a process flow diagram of another method for preparing a single-crystal silicon rod provided in some embodiments of this application.

[0042] The reference numerals in the detailed embodiments are as follows:

[0043] 10. Flow guide tube; 11. Outer wall; 111. Inclined section; 1111. First end; 1112. Second end;

[0044] 20. Crucible; 21. Gas passage;

[0045] 30. Adjustment mechanism; 31. First adjusting member; 311. First surface; 312. Second surface; 32. Second adjusting member; 33. Third adjusting member; 331. First side; 332. Second side; 34. Fourth adjusting member;

[0046] 40. Drive mechanism;

[0047] F1, first direction; F2, second direction; F3, third direction. Detailed Implementation

[0048] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0049] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0050] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0051] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., 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, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0052] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0053] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0054] According to some embodiments of this application, see [link / reference]. Figure 1 and Figure 2 , Figure 1 and Figure 2A schematic diagram of the single crystal furnace under different operating conditions is shown. Some embodiments of this application provide a single crystal furnace including a flow guide tube 10, a crucible 20, and an adjustment mechanism 30. The flow guide tube 10 is located on the top side of the crucible 20. The adjustment mechanism 30 includes a first adjustment member 31 and a second adjustment member 32. One end of the first adjustment member 31 is rotatably connected to the outer side wall 11 of the bottom of the flow guide tube 10, and the other end of the first adjustment member 31 is rotatably connected to the second adjustment member 32. The second adjustment member 32 is configured to move relative to the flow guide tube 10 along a preset direction, which is parallel to the direction from the top side of the flow guide tube 10 to the bottom side of the flow guide tube 10.

[0055] In this application, the flow guide tube 10 is a cylindrical structure installed above the crucible to guide the flow path of the gas (such as argon) inside the furnace; the crucible 20 is a container for holding silicon material, continuously supplying molten silicon material for the growth of the crystal rod during the crystal pulling process. Exemplarily, the flow guide tube 10 is vertically installed above the crucible 20, its cylindrical body extending axially downwards, with its bottom corresponding vertically to the upper edge of the crucible 20.

[0056] See Figure 3 and Figure 4 , Figure 3 and Figure 4 The diagram shows the gas flow direction inside the single crystal furnace in different operating states. The adjustment mechanism 30 refers to the movable component located on the outer side wall 11 of the guide tube 10, which is used to adjust the shape of the gas channel 21 between the guide tube 10 and the crucible 20.

[0057] The shape of the gas channel 21 refers to the geometric shape of the space formed between the bottom of the guide tube 10 and the upper edge of the crucible 20, which is used for gas flow in the furnace. This mainly includes the size of its flow cross-sectional area and the airflow guiding angle. By changing the position of components such as the first adjusting member 31 and the first adjusting member 32 through the adjusting mechanism 30, the geometric shape of the aforementioned space can be dynamically adjusted, thereby changing the flow rate, velocity, direction, and flow state of the gas passing through the channel. This achieves optimized control of the airflow distribution and volatile discharge path within the furnace, thereby improving the crystal quality of the single-crystal silicon rod.

[0058] For example, the preset direction is parallel to the first direction F1, and the first direction F1, the second direction F2, and the third direction F3 intersect each other. For example, the first direction F1, the second direction F2, and the third direction F3 are perpendicular to each other.

[0059] According to some embodiments of this application, in conjunction with Figure 3 and Figure 4The adjustment mechanism 30 can dynamically change the shape of the gas channel 21 below the guide tube 10 during the crystal pulling process. For example, when the second adjustment member 32 moves along a preset direction, it can drive the first adjustment member 31 to move, thereby changing the position of the first adjustment member 31 relative to the guide tube 10. This change in position will directly affect the shape of the gas channel 21 between the guide tube 10 and the crucible 20, thereby controlling the discharge path of volatiles and the gas flow state in the single crystal furnace.

[0060] It is important to understand that the oxygen in the single-crystal rod mainly originates from the reaction between the crucible 20 and the molten silicon within it at high temperatures, generating volatile silicon monoxide gas. During the Czochralski single-crystal growth process, the crucible 20 is continuously subjected to thermal erosion, and some of the generated silicon monoxide gas dissolves in the silicon melt and enters the crystal lattice through the solid-liquid interface during crystal growth. Furthermore, process conditions such as melt convection, argon gas flow field, furnace pressure, and crucible 20 rotation speed also affect the dissolution, transport, and volatilization of oxygen, ultimately determining the oxygen content and distribution in the rod. The presence of oxygen in the single-crystal silicon rod affects its quality. While a fixed-angle external guide structure can maintain basic crystal pulling stability, it cannot effectively control the oxygen volatilization path, easily leading to oxygen donor formation, which in turn causes problems such as distorted resistivity measurements and increased rod defects. This application, however, adjusts the morphology of the gas channel 21 through the adjustment mechanism 30, enabling directional guidance and constraint of the gas flow at different crystal pulling stages. This dynamic adjustment mechanism enables controllable intervention in the oxygen volatilization pathway, thereby reducing the oxygen content in the monocrystalline silicon rod while ensuring the stability of crystal pulling, ultimately achieving the goal of improving the quality and electrical performance of the monocrystalline silicon rod.

[0061] Combination Figure 4 When the second adjusting element 32 moves away from the crucible 20 along a preset direction, the gas passage 21 between the guide tube 10 and the crucible 20 expands, reducing the airflow resistance inside the furnace, which facilitates the rapid passage of volatiles and enhances the discharge efficiency of volatiles. Figure 3 When the second adjusting member 32 moves towards the crucible 20 along a preset direction, the gas channel 21 between the guide tube 10 and the crucible 20 narrows, which can form a more stable gas flow layer near the crystal growth interface. The setting of the single crystal furnace adjustment mechanism 30 makes the shape of the gas channel 21 in the furnace adjustable, thereby flexibly optimizing the process environment at different crystal pulling stages, improving the quality of the prepared single crystal silicon rod, and thus further improving the overall performance of the material.

[0062] In conventional single-crystal furnace structures, gas channels 21 employ fixed geometric configurations or can only be adjusted via simple on / off switching. This single or discrete adjustment method is difficult to adapt to the dynamically changing thermal field conditions during crystal pulling, and it also fails to meet the process requirements for refined and continuous control of oxygen volatilization. The generation and volatilization of oxygen is a continuous process that changes over time. Especially during the constant-diameter growth stage, the temperature field at the crystal interface, the melt convection state, and the oxygen release rate are all constantly evolving. If the shape of gas channels 21 cannot be adjusted in a corresponding continuous and refined manner, it can easily lead to local airflow turbulence, obstruction of oxygen volatilization paths, or excessive dissipation, resulting in uneven distribution of oxygen content in the axial and radial directions of the crystal rod, ultimately affecting the consistency of resistivity and crystal quality.

[0063] This application achieves real-time matching between the morphology of the gas channel 21 and the crystal growth process by setting up a continuously and precisely adjustable adjustment mechanism 30, so that the oxygen volatilization path is always in an optimized state, which is also the key to achieving stable preparation of high-quality, low-oxygen-content single-crystal silicon rods.

[0064] According to some embodiments of this application, see [link / reference]. Figure 5 The first adjusting member 31 has a first surface 311 facing the guide tube 10, and the shape of the first surface 311 is adapted to the shape of the outer wall 11 of the guide tube 10.

[0065] Shape matching refers to the fact that the contour curvature of the first surface 311 and the contour of the outer wall 11 in the area where they connect are highly consistent or mutually matched. This design allows the first adjusting member 31 to remain in close or near-close contact with the outer wall of the guide tube 10 during rotation, reducing the gap between them and effectively avoiding the generation of local eddies. This allows the airflow to flow smoothly and orderly along the guide surface formed by the first adjusting member 31. This closely matched structure not only improves the accuracy and stability of airflow guidance, which is conducive to the formation of a controllable airflow field, but also reduces the temperature fluctuations in the furnace caused by structural mismatch, further optimizing the thermal environment of the crystal growth interface and playing a positive role in suppressing the formation of defects in the crystal rod.

[0066] Furthermore, because the first surface 311 and the outer wall 11 of the guide tube 10 maintain a high degree of dynamic fit, every minute displacement of the first adjusting component 31 during rotation can be precisely and smoothly translated into a continuous change in the shape of the gas channel 21. This seamless motion characteristic eliminates the airflow steps and disturbances caused by component separation or abrupt gap changes in traditional discrete adjustment methods, thus allowing for fine, gradual, and stable real-time adjustments to parameters such as channel opening and airflow guiding angle according to the needs of the crystal pulling process. It is precisely based on this high-precision continuous adjustment capability that this application can dynamically adapt to the different requirements of the airflow field at each stage of crystal growth, achieve fine control of the oxygen volatilization path, and provide a reliable guarantee for obtaining single-crystal silicon rods with low oxygen content and high uniformity.

[0067] For example, the single crystal furnace of this application also includes a furnace body, a heater, a heat preservation system, a pulling mechanism, a rotating mechanism, an atmosphere control system, and an exhaust system. The furnace body provides space for the entire crystal growth process; the heater is used to heat the silicon material in the crucible 20 to a molten state; the heat preservation system is used to maintain the uniformity and stability of the temperature distribution inside the furnace. The pulling mechanism is used to drive the seed crystal to perform steps such as crystal pulling, shoulder formation, and constant diameter growth. The rotating mechanism can drive the seed crystal and the crucible 20 to rotate independently. By adjusting the rotation direction and speed of the two, the thermal field distribution and flow state in the melt are improved, thereby enhancing the stability of the crystal growth interface. The atmosphere control system, by adjusting the gas intake and furnace pressure, works in conjunction with the exhaust system to maintain a clean and stable gas environment inside the furnace, thereby effectively controlling the volatilization process of impurities. In addition, the single crystal furnace also includes a monitoring and control system to monitor key process parameters such as temperature, pressure, pulling speed, and rotation speed in real time.

[0068] These components work in conjunction with the flow guide tube 10, crucible 20, and adjustment mechanism 30 to provide a reliable equipment foundation for the reproducible preparation of high-quality, low-oxygen-content single-crystal silicon rods.

[0069] It should be noted that the drawings described in this application (including) Figures 1 to 5 All figures are semi-sectional schematic diagrams, intended only to clearly and concisely illustrate the structural principles, relative positions of components, and gas flow direction of the embodiments of this application, and do not represent the precise proportions, dimensions, shapes, or structural details of actual devices or components. Some features in the figures may be simplified, enlarged, or schematically represented, and some conventional components or structures may be omitted to highlight the innovative points of this application. Those skilled in the art can make reasonable adjustments to the specific implementation methods of the illustrated embodiments based on common knowledge in the field and actual process requirements.

[0070] Based on some embodiments of this application, continuing to combine Figure 5The first adjusting member 31 has a second surface 312 disposed opposite to the guide tube 10, and the second surface 312 is arc-shaped. The second surface 312 is arc-shaped, meaning that the cross-sectional profile of the surface along its extension direction presents a smooth arc curve with continuous curvature.

[0071] In this application, the arc shape of the second surface 312 of the first regulating member 31 facilitates the smooth transition of the gas flow in the furnace along the second surface 312, thereby forming a more stable gas flow layer between the guide tube 10 and the crucible 20. It can also effectively guide the volatiles to be discharged in an orderly manner along a predetermined direction, avoiding their retention or backflow near the interface, further suppressing the diffusion of oxygen into the crystal, and helping to achieve the growth of low-oxygen, low-defect single-crystal silicon rods.

[0072] According to some embodiments of this application, the first adjusting member 31 and / or the second adjusting member 32 are made of a high-temperature resistant material. Exemplarily, the first adjusting member 31 and / or the second adjusting member 32 are composed of at least one of carbon, molybdenum, tungsten, or other alloy materials with a surface coated with a high-temperature resistant coating.

[0073] Using high-temperature resistant materials ensures that the regulating component maintains good structural stability and mechanical strength in the high-temperature environment of the crystal pulling process, preventing dimensional changes due to thermal deformation and thus guaranteeing the stability of the gas channel 21 morphology adjustment. The high-temperature resistant material regulating component possesses a stable structure, which helps maintain the morphology of the gas channel 21, making the oxygen volatilization path controllable and providing a reliable structural foundation for continuously obtaining high-quality single-crystal silicon rods with low oxygen and low impurities. Simultaneously, it extends the service life of the regulating mechanism 30 and reduces maintenance costs.

[0074] Based on some embodiments of this application, continuing to combine Figure 1 and Figure 5 The adjustment mechanism 30 also includes a third adjustment member 33. One end of the third adjustment member 33 is rotatably connected to the first adjustment member 31, and the other end of the third adjustment member 33 is rotatably connected to the second adjustment member 32.

[0075] The third adjusting member 33 is an auxiliary component in the adjusting mechanism 30, located between the first adjusting member 31 and the second adjusting member 32. In this application, the third adjusting member 33 enhances the rigidity and motion stability of the overall adjusting mechanism 30.

[0076] For example, the third adjusting member 33 is a chain structure or a linkage mechanism. Through this chain structure or linkage mechanism, the linear displacement of the second adjusting member 32 can be more accurately and smoothly converted into the planar motion of the first adjusting member 31. This design helps reduce the wobbling or gaps that may exist at a single hinge point, thereby improving the accuracy of position adjustment of the first adjusting member 31 during high-temperature, long-duration crystal pulling processes. This enables fine adjustment of the gas channel 21's shape, providing more reliable mechanical support for optimizing furnace airflow and stabilizing the discharge path of volatiles.

[0077] Based on some embodiments of this application, continuing to combine Figure 5 The third adjusting member 33 has a first side 331 disposed away from the crucible 20 and a second side 332 disposed opposite to the first side 331. The third adjusting member 33 is recessed from the first side 331 to the second side 332. For example, the second side 332 of the third adjusting member 33 is constructed as an arc surface.

[0078] In this application, the recessed design of the third adjusting member 33 from the first side 331 to the second side 332, and the arcuate design of the second side 332, provides stable support and guidance for the first adjusting member 31. Simultaneously, the arcuate second side 332 guides the airflow through a smooth transition, reducing airflow disturbances or eddies caused by structural changes.

[0079] Based on some embodiments of this application, continuing to combine Figure 5 The outer wall 11 at the bottom of the guide tube 10 includes an inclined section 111, and the first adjusting member 31 is rotatably disposed on the inclined section 111. By disposing the first adjusting member 31 on the inclined section 111, the positional change of the first adjusting member 31 can directly and effectively change the shape and gas flow angle of the gas channel 21 between the end of the guide tube 10 and the crucible 20, thereby achieving precise control of the oxygen volatilization path.

[0080] Based on some embodiments of this application, continuing to combine Figure 5 The inclined section 111 has a first end 1111 near the crucible 20 and a second end 1112 away from the crucible 20. The angle between the direction of the first end 1111 pointing to the second end 1112 and a preset direction is a first angle. The direction of the first adjusting member 31 connected to one end of the guide tube 10 and the direction of the first adjusting member 31 connected to one end of the second adjusting member 32, forms an angle within the range of [0°, 45°] with the direction of the first end 1111 pointing to the second end 1112. For example, the direction of the first adjusting member 31 connected to one end of the guide tube 10 and the direction of the first adjusting member 31 connected to one end of the second adjusting member 32 is parallel to the second direction F2.

[0081] For example, the first adjusting member 31 is rotatably disposed at the lowest edge of the inclined section 111. For instance, the first adjusting member 31 is rotatably disposed at the first end 1111.

[0082] The lowest edge refers to the position on the inclined section 111 closest to the bottom edge or end of the crucible 20. Rotating the first adjusting member 31 at this location maximizes the guiding effect of the inclined section 111. This position directly determines the initial shape of the gas channel 21, allowing the rotational adjustment of the first adjusting member 31 to most effectively act on the flow region near the melt surface, thereby enhancing the control over the volatile discharge path and the gas flow environment at the crystal growth interface.

[0083] For example, the direction in which the first adjusting member 31 is connected to one end of the guide tube 10 and the direction in which the first adjusting member 31 is connected to the second adjusting member 32 form an angle range of 0°, 15°, 30°, and 45° with the direction in which the first end 1111 points to the second end 1112. Of course, it can also be any other value within the range of 0° to 45°, and no specific limitation is made here.

[0084] Combination Figure 3 and Figure 4 This angle range allows the first adjusting member 31 to be flexibly adjusted within a range from being attached to the inclined section 111 of the guide tube 10 to forming a 45° angle with it. When the angle is 0°, the first adjusting member 31 is attached to the inclined section 111, and the flow area of ​​the gas channel 21 is at its maximum; when the angle increases to 45°, the first adjusting member 31 expands outward, and the flow area of ​​the gas channel 21 is at its minimum. This controllable angle change can adapt to the requirements of airflow speed and distribution at different crystal pulling stages, thereby helping to reduce the oxygen content in the single crystal silicon rod.

[0085] For example, the first angle is in the range of [30°, 60°]. This range defines the inherent structural inclination angle of the bottom inclined section 111 of the guide tube 10.

[0086] When the adjustment mechanism 30 is not installed in the single crystal furnace, the inherent structural tilt angle of the inclined section 111 at the bottom of the guide tube 10 can provide stable guidance for the initial airflow. When the adjustment mechanism 30 is installed in the single crystal furnace, the tilt angle range of the inclined section 111 works in conjunction with the adjustable first adjustment element 31 to provide a reliable structural basis for the dynamic optimization of the gas channel 21 throughout the crystal pulling process.

[0087] For example, the first angle can be 30°, 40°, 50°, or 60°. Of course, the first angle can also be any other value within the range of 30° to 60°, without any specific limitation.

[0088] For example, the first angle is 45°. The 45° tilt angle provides sufficient adjustment space and mechanical rationality for the subsequent position adjustment of the first adjusting member 31, allowing it to flexibly change within the range of 0° to 45° on this reference.

[0089] Continue to combine Figure 5 In one embodiment, the first adjusting member 31 is connected to one end of the guide tube 10, and the direction pointing to the end of the first adjusting member 31 connected to the second adjusting member 32 is within the angle range of [45°, 90°] with the preset direction.

[0090] For example, the direction in which the first adjusting member 31 is connected to one end of the guide tube 10 and points towards the end of the first adjusting member 31 connected to the second adjusting member 32 can be at an angle of 45°, 60°, 75° or 90° with respect to a preset direction. Of course, the angle in which the direction in which the first adjusting member 31 is connected to one end of the guide tube 10 and points towards the end of the first adjusting member 31 connected to the second adjusting member 32 can be any other value within the range of 45° to 90°, and no specific limitation is made here.

[0091] According to some embodiments of this application, in conjunction with Figure 1 The adjustment structure also includes a fourth adjustment member 34, one end of which is rotatably connected to the first adjustment member 31, and the other end of which is rotatably connected to the guide tube 10.

[0092] The fourth adjusting member 34 is an auxiliary component in the adjusting mechanism 30, and is located between the first adjusting member 31 and the guide tube 10.

[0093] In this application, the fourth adjusting member 34 realizes the positional change of the first adjusting member 31 relative to the guide tube 10 and can effectively share the thermal stress and mechanical load borne by the first adjusting member 31, preventing it from shifting or vibrating in a high-temperature environment, which helps to improve the accuracy and repeatability of angle adjustment. At the same time, this design enhances the structural stability and reliability of the adjusting mechanism 30 during long-term crystal pulling, making the control of the gas channel 21 more stable, thereby ensuring the stable implementation of crystal pulling.

[0094] According to some embodiments of this application, in conjunction with Figure 1 The single crystal furnace also includes a drive mechanism 40, which is connected to the second adjustment member 32. The drive mechanism 40 is used to drive the second adjustment member 32 to move along a preset direction.

[0095] For example, the drive mechanism 40 is one of an electric actuator, a servo motor, a pneumatic device, or a hydraulic device, and achieves precise displacement and speed control through a control system.

[0096] The drive mechanism 40 automates and programs the adjustment of the position of the second adjusting member 32, allowing the angle between the first adjusting member 31 and the tilting section 111 to be dynamically adjusted according to the preset crystal pulling process. Automated control not only eliminates the uncertainty of manual intervention and ensures high repeatability of process parameters, but also facilitates coordination with other process parameters within the furnace (such as argon flow rate and furnace pressure) to support the stable and efficient preparation of low-oxygen, low-impurity single-crystal silicon rods.

[0097] According to some embodiments of this application, please refer to Figure 6 This application also provides a method for preparing a single-crystal silicon rod, wherein the single-crystal silicon rod is prepared using any of the single-crystal furnaces described above, and the preparation method includes the following steps:

[0098] Step S110: During the crystal pulling process, control the position of the second adjusting member to adjust the position of the first adjusting member relative to the guide tube.

[0099] In step S110, the position of the second adjusting member 32 is adjusted to change the position of the first adjusting member 31 relative to the guide tube 10, thereby changing the shape of the gas channel 21 to match different stages of crystal pulling.

[0100] This step, by actively regulating the gas channel 21, can reduce the oxygen content in the single crystal silicon rod while maintaining the stability of the crystal pulling process, thereby improving the accuracy of resistivity measurements of the single crystal silicon rod.

[0101] According to some embodiments of this application, please refer to Figure 7 During the crystal pulling process, controlling the second adjusting member 32 to move along a preset direction to adjust the position of the first adjusting member 31 relative to the guide tube 10 includes the following steps:

[0102] Step S111: During the shoulder placement process, control the second adjusting member to be in the first position, and keep the first adjusting member in the second position; wherein, the end of the first adjusting member connected to the guide tube points to the direction of the end of the first adjusting member connected to the second adjusting member, and the angle between the first adjusting member and the preset direction is the preset angle; the first adjusting member is in the second position, and the preset angle is the initial angle;

[0103] Step S112: During the equal diameter growth process, control the second adjusting member to move along the preset direction, so that the preset angle decreases from the initial angle to 0° and remains unchanged until the equal diameter growth process ends.

[0104] In step S111, the shoulder formation process refers to the initial stage of crystal pulling. At this time, the second adjusting member 32 of the adjusting mechanism 30 is fixed in the first position, thereby driving the first adjusting member 31 to remain in the corresponding second position. In this state, the line connecting one end of the first adjusting member 31 to the guide tube 10 and the end connecting the first adjusting member 31 to the second adjusting member 32 forms a specific angle with a preset direction. This angle is defined as the preset angle, and when the first adjusting member 31 is in the second position, this preset angle is the initial angle.

[0105] By stabilizing the first adjusting member 31 at the initial angle position, a suitable gas channel 21 shape can be formed during the shoulder formation stage, providing a basis for dynamic adjustment in the subsequent constant diameter growth process. At the same time, maintaining a stable gas flow environment in the early stage of crystal growth is beneficial to suppressing the diffusion of oxygen into the crystal, providing a good process starting point for the preparation of high-quality single crystal silicon rods.

[0106] In step S112, during the constant diameter growth process of crystal pulling, the second adjusting member 32 is controlled to move along a preset direction, gradually driving the first adjusting member 31 to rotate, so that the preset angle gradually decreases from its initial angle to 0°. When the preset angle reaches 0°, the first adjusting member 31 is basically in contact with the outer wall of the guide tube 10, and the shape of the gas channel 21 tends to the maximum flow cross-section. Thereafter, this angle is kept unchanged until the constant diameter growth process is completed.

[0107] This adjustment method can effectively guide the flow of gas and volatiles in the single crystal furnace along the gas channel 21 during the constant diameter growth process, avoiding stagnation near the growth interface of the single crystal silicon rod. This helps to reduce the diffusion of oxygen into the crystal rod, inhibit the formation of oxygen donors, and improve the authenticity and accuracy of the crystal rod resistivity measurement.

[0108] In one embodiment, the initial angle ranges from [75° to 90°], and the preset angle is the initial angle. During the constant diameter growth process, the preset angle is reduced to 0° at a rate of 1° every 10 to 25 minutes.

[0109] For example, the initial angle can be 75°, 80°, 85°, or 90°. Of course, the initial angle can also be any other value within the range of 75° to 90°, without any specific limitation.

[0110] For example, during the constant diameter growth process, the preset angle can be gradually adjusted to 0° at a rate of 1° decrease every 10 minutes, 15 minutes, 20 minutes, or 25 minutes. Of course, any time period within the range of 10 minutes to 25 minutes can also be selected to complete the angle adjustment, and the specific adjustment speed is not limited.

[0111] During constant-diameter growth, gradually reducing the preset angle to 0° at a relatively slow and uniform rate allows for a smooth transition in the gas channel 21's shape, reducing airflow disturbances or temperature fluctuations that may be caused by abrupt angle changes. This angle adjustment strategy, in conjunction with the silicon rod growth rate, gradually adjusts the airflow guidance effect between the guide tube 10 and the crucible 20, enhancing continuous control over the oxygen volatilization path. This effectively suppresses oxygen diffusion into the silicon rod throughout the constant-diameter growth process, contributing to obtaining single-crystal silicon rods with more uniform oxygen content distribution and higher resistivity consistency. Simultaneously, this rate range balances process operability and adjustment precision, providing a reliable and flexible parameter window for actual production.

[0112] According to some embodiments of this application, please refer to Figure 6 The preparation method of single-crystal silicon rods also includes the following steps:

[0113] Step S120a: During the constant diameter growth process, reduce the argon flow rate in the single crystal furnace.

[0114] In step S120a, the flow rate of argon gas in the single crystal furnace can be reduced simultaneously, that is, as the crystal grows stably, the flow rate of argon gas introduced into the furnace is gradually reduced.

[0115] By gradually reducing the argon flow rate during the constant-diameter growth process, it is possible to coordinate with the adjustment of the gas channel 21 morphology to further optimize the gas flow inside the furnace. As the constant-diameter growth stage of the single-crystal silicon rod continues, the growth interface tends to stabilize. Appropriately reducing the argon flow rate helps to form a more stable gas flow below the guide tube 10, reducing temperature fluctuations and interface disturbances caused by large gas flow rates.

[0116] This flow control strategy, combined with the morphology adjustment of gas channel 21, enables precise control over the oxygen transport path and volatilization efficiency, further reducing the oxygen content in the monocrystalline silicon rod.

[0117] According to some embodiments of this application, reducing the argon flow rate in a single crystal furnace includes a first flow reduction stage, a second flow reduction stage, and a third flow reduction stage executed sequentially. The argon flow rate in the first flow reduction stage is greater than the argon flow rate in the second flow reduction stage, and the argon flow rate in the second flow reduction stage is greater than the argon flow rate in the third flow reduction stage.

[0118] The first, second, and third flow reduction stages refer to the continuous process of gradually and progressively reducing the argon flow rate from a high initial value to a lower target value during the constant diameter growth process. For example, these three stages are executed sequentially, with each stage corresponding to a flow range. For instance, starting from the constant diameter growth, the first flow reduction stage adjusts the argon flow rate from the initial flow rate to the first flow range; then the second flow reduction stage further adjusts the flow rate to a lower second flow range; finally, the third flow reduction stage adjusts the flow rate to the predetermined minimum flow range and maintains it until the end of that growth stage.

[0119] For example, the initial flow rate range during the constant diameter growth process is [120 lpm, 140 lpm], the argon flow rate range during the first flow rate reduction stage is [110 lpm, 120 lpm], the argon flow rate range during the second flow rate reduction stage is [100 lpm, 110 lpm], and the argon flow rate range during the third flow rate reduction stage is [90 lpm, 100 lpm].

[0120] By gradually reducing the argon flow rate in stages, precise and progressive control of the gas flow within the furnace is achieved. Dividing the flow rate reduction process into three successively decreasing stages helps to achieve a smooth transition of the gas flow within the furnace, reducing disturbances to the crystal growth interface caused by rapid changes in argon flow rate. A higher initial flow rate helps maintain a strong volatile carrying capacity in the early stages of constant-diameter growth; as the growth process progresses, the gradual reduction in stages allows the gas flow to gradually become gentler, which is conducive to more stable crystal growth. At the same time, the staged adjustment provides a clear operating window, enhancing the repeatability and stability of the preparation method.

[0121] According to some embodiments of this application, please refer to Figure 8 The preparation method of single-crystal silicon rods also includes the following steps:

[0122] Step S120b: During the constant diameter growth process, reduce the furnace pressure inside the single crystal furnace; or, during the constant diameter growth process, keep the furnace pressure constant.

[0123] In step S120b, two furnace pressure control strategies can be adopted: one is to gradually reduce the furnace pressure inside the single crystal furnace; the other is to keep the furnace pressure constant. Specific control strategies are not limited here.

[0124] Regardless of whether a voltage reduction or stabilization strategy is chosen, it can be coordinated with the aforementioned measures such as the adjustment of gas channel 21 and argon flow control to jointly construct a stable and controllable crystal growth environment, so as to effectively suppress oxygen content and defects in the constant diameter stage, and ultimately improve the electrical performance and resistivity measurement accuracy of the single crystal silicon rod.

[0125] According to some embodiments of this application, reducing the furnace pressure in a single crystal furnace includes a first pressure reduction stage and a second pressure reduction stage performed sequentially.

[0126] For example, the initial furnace pressure ranges from [6 torr, 7 torr] during the constant diameter growth process, the furnace pressure ranges from [5 torr, 6 torr] during the first depressurization stage, and the furnace pressure ranges from [4 torr, 5 torr] during the second depressurization stage.

[0127] During the constant-diameter growth process, the furnace pressure is reduced in stages, gradually decreasing from an initial 6-7 torr to 5-6 torr, and finally to 4-5 torr. This is because lower furnace pressure results in a faster argon gas flow rate, which strengthens the purging effect on the melt surface, effectively carrying away silicon oxide gas from the melt and thus reducing the oxygen content in the single-crystal silicon rod. Continuing to reduce the furnace pressure during the constant-diameter stage further enhances this effect, making it suitable for single-crystal silicon rods with extremely high oxygen content requirements.

[0128] Furthermore, in the later stages of constant-diameter formation, the melt volume decreases and the liquid level drops, increasing the exposed area of ​​crucible 20 and potentially increasing oxygen release. Gradually reducing the furnace pressure can continuously enhance argon convection, suppress oxygen accumulation, and make the oxygen content of the entire crystal rod more uniform. The staged pressure reduction method allows for a smooth transition, avoiding the impact of sudden pressure changes on the stability of the growth interface, and enhancing the controllability and repeatability of the preparation method.

[0129] If the furnace pressure is kept constant during the constant diameter growth process, the operation process can be simplified, which is suitable for growth scenarios that require process stability.

[0130] For example, the parameters for argon flow rate and furnace pressure during the shoulder release process are set as shown in Table 1:

[0131] Table 1

[0132]

[0133] Table 1 lists exemplary settings for process parameters during the shoulder formation stage. During this stage, the parameters are gradually adjusted with the shoulder length to match the crystal diameter expansion process. The argon flow rate remains constant at 130 lpm during this stage to maintain sufficient gas flow carrying capacity; the furnace pressure is increased from 6 Torr to 7 Torr in the later stages of shoulder formation; crystal rotation and crucible rotation are set at 6 rpm and 4.5 rpm, respectively; the crucible rise begins to gradually increase in the later stages of shoulder formation to compensate for the drop in liquid level. These parameters work synergistically to lay a stable flow field foundation for constant-diameter crystal growth.

[0134] For example, the parameters for argon flow rate and furnace pressure during the constant diameter growth process are shown in Table 2:

[0135] Table 2

[0136]

[0137] Table 2 lists exemplary settings for process parameters during the constant diameter growth stage. In this stage, parameters are adjusted step-by-step according to the constant diameter length to meet the requirements of continuous and stable crystal growth. The pulling speed is gradually increased from the initial to the middle stages of constant diameter growth to maintain a stable crystal diameter, and then slightly reduced in the later stages to compensate for the decrease in melt volume. The argon flow rate is gradually reduced in stages, from an initial 130 lpm to 100 lpm. This reduction process is coordinated with the adjustment of the gas channel to achieve a smooth transition of the gas flow field and optimize the oxygen volatilization path. The furnace pressure is gradually reduced from 7 Torr to 5 Torr during the constant diameter stage. By reducing the pressure, the carrying effect of argon on volatiles is enhanced, further suppressing oxygen diffusion into the crystal. The crucible rotation is gradually increased as the growth progresses to enhance melt stirring and improve oxygen distribution uniformity. This set of parameters, together with the morphology adjustment of gas channel 21, constitutes a complete constant diameter growth control strategy, aiming to achieve stable preparation of single-crystal silicon rods with low oxygen content and high uniformity.

[0138] It should be noted that the power values ​​(unit: kW) listed in Tables 1 and 2 are adjustments to the base power during the crystal pulling process. The base power is set within the range of 40kW to 55kW according to process requirements. The values ​​shown in the "Power" column of the tables (e.g., -0.5, -1, -3.7, 4, etc.) indicate the number of kilowatts that need to be added or reduced from this base value. For example, if the base power is set to 45kW and a power value in the table is marked as "-1", then the actual applied power is 44kW. This notation method clarifies the relativity of power adjustment; the actual operating power is the algebraic sum of the base value and the adjustment amount in the table.

[0139] According to some embodiments of this application, please refer to Figure 6 or Figure 8 The preparation method of single-crystal silicon rods also includes the following steps:

[0140] Step S130: During the cooling process, control the second adjusting member to move along the preset direction so that the preset angle is adjusted to the initial angle.

[0141] In step S130, the second adjusting member 32 is controlled to move along a preset direction, causing the first adjusting member 31 to gradually rotate, so that the preset angle gradually recovers from 0° at the end of the equal diameter growth to the initial angle set in the shoulder-growing stage.

[0142] Adjusting the preset angle to the initial angle prepares the material for subsequent crystal pulling and helps keep the position of the adjustment mechanism 30 consistent across multiple process cycles. This supports the stability and repeatability of the single crystal silicon rod preparation process, providing a solid foundation for the long-term and continuous production of high-quality single crystal silicon rods.

[0143] The preparation process of single-crystal silicon rods will be described in general below with reference to some specific adjustment methods illustrated in the above embodiments.

[0144] For example, a method for preparing a single-crystal silicon rod includes the following steps:

[0145] Step S01: During the shoulder-laying process, control the second adjusting member to be in the first position, and keep the first adjusting member in the second position; wherein, the end of the first adjusting member connected to the guide tube points to the direction of the end of the first adjusting member connected to the second adjusting member, and the angle between the first adjusting member and the preset direction is the preset angle; the first adjusting member is in the second position, and the preset angle is the initial angle;

[0146] Step S02: During the constant diameter growth process, control the second adjusting member to move along the preset direction, so that the preset angle decreases from the initial angle to 0° and remains unchanged until the constant diameter growth process ends; during the constant diameter growth process, reduce the argon flow rate in the single crystal furnace; during the constant diameter growth process, reduce the furnace pressure in the single crystal furnace; or, during the constant diameter growth process, keep the furnace pressure constant.

[0147] Step S03: During the cooling process, control the second adjusting member to move along the preset direction so that the preset angle is adjusted to the initial angle.

[0148] In step S01, the shoulder-forming stage is the initial forming period of crystal growth. This step stabilizes the first adjusting member 31 in the corresponding second position by fixing the second adjusting member 32 in the first position. At this time, the angle formed between the first adjusting member 31 and the preset direction is defined as the preset angle, which remains at the initial angle (e.g., within the range of 75° to 90°) during the shoulder-forming stage. This setting can establish a suitable gas channel 21 shape in the early stage of growth, providing stable initial conditions for dynamic adjustment in the subsequent constant diameter growth stage, while also helping to maintain the stability of the airflow near the crystal growth interface, laying the foundation for the growth of high-quality single-crystal silicon rods.

[0149] For example, the initial angle is 90°. When the initial angle is 90°, the line connecting one end of the first adjusting member 31 to the guide tube 10 and the end connecting the second adjusting member 32 is parallel to the second direction F2, and at this time the first adjusting member 31 is in a horizontally extended state. This design keeps the gas channel 21 formed between the guide tube 10 and the crucible 20 in a relatively narrow shape during the shoulder formation process and the early stage of constant diameter growth. Its design principle is mainly based on the following points: First, the horizontally extended first adjustment component 31 can effectively guide the argon gas to flow closely against the outer wall of the guide tube 10, forming a stable and concentrated gas flow layer near the melt surface, enhancing the constraint and guidance effect on volatiles, and suppressing their re-dissolution, thereby creating favorable conditions for controlling the initial oxygen content of the crystal; Second, this angle setting can provide strong gas flow stability in the early stage of crystal pulling, which helps to buffer thermal field fluctuations, maintain the stability of the liquid surface, and improve the survival rate and structural integrity of the crystal nucleation and shoulder formation stages; In addition, setting the initial angle to the upper limit of the adjustable range provides sufficient control space for the continuous and gradual angle adjustment in the subsequent constant diameter growth stage, which is conducive to achieving a smooth transition of the gas flow environment from "high constraint and high stability" to "high flow and strong exhaust", adapting to the differentiated needs of oxygen control and thermal management in different growth stages. In step S02, by controlling the second adjusting member 32 to move along a preset direction, the first adjusting member 31 is driven to rotate gradually, so that the preset angle is reduced from the initial angle to 0°, thereby realizing the regulation of the shape of the gas channel 21, thereby optimizing the airflow distribution and strengthening the guidance of the oxygen volatilization path.

[0150] Meanwhile, by gradually reducing the argon flow rate in stages (e.g., through the first, second, and third flow reduction stages sequentially), the gas flow velocity inside the furnace can be slowed down, which, in conjunction with the change in channel morphology, further stabilizes the growth interface. The first, second, and third flow reduction stages refer to the continuous process of gradually and in stages reducing the argon flow rate from a relatively high initial value to a lower target value during the constant diameter growth process.

[0151] For example, these three stages are executed sequentially in chronological order, with each stage corresponding to a flow range. For instance, starting from the constant diameter growth stage, the first stage of flow reduction begins, adjusting the argon flow rate from the initial flow rate to the first flow range; then the second stage of flow reduction begins, further adjusting the flow rate to a lower second flow range; finally, the third stage of flow reduction begins, adjusting the flow rate to the predetermined minimum flow range and maintaining it until the end of the growth stage.

[0152] In the first flow reduction stage, a larger initial angle is used to improve the crystal growth success rate. This larger angle design increases the saturated vapor pressure of silicon vapor and reduces surface fluctuations. In the second flow reduction stage, the angle is gradually reduced by controlling the adjustment mechanism 30. This gradual adjustment strategy aims to create smooth transition conditions for subsequent crystal growth with low oxygen content. Slow adjustment aims to maintain the thermodynamic and kinetic stability of the crystal growth interface, avoiding melt disturbances induced by sudden changes in airflow or thermal field, thereby preventing the unintended nucleation and growth of stray crystal nuclei, ensuring the integrity and uniformity of the single crystal structure, and effectively suppressing the risk of polymorphism. In the third flow reduction stage, the crystal pulling process generally stabilizes. At this point, the angle is gradually reduced to 0° to allow silicon vapor to evaporate as much as possible, resulting in a single crystal silicon rod with even lower oxygen content.

[0153] For example, the initial flow rate range during the constant diameter growth process is [120 lpm, 140 lpm], the argon flow rate range during the first flow rate reduction stage is [110 lpm, 120 lpm], the argon flow rate range during the second flow rate reduction stage is [100 lpm, 110 lpm], and the argon flow rate range during the third flow rate reduction stage is [90 lpm, 100 lpm].

[0154] During the constant diameter growth process, the furnace pressure can be gradually reduced (e.g., through the first and second depressurization stages in sequence) or kept constant: reducing the furnace pressure helps to enhance the carrying capacity of argon for volatiles, while keeping the furnace pressure is beneficial to the stability of the process operation.

[0155] For example, the initial furnace pressure ranges from [6 torr, 7 torr] during the constant diameter growth process, the furnace pressure ranges from [5 torr, 6 torr] during the first depressurization stage, and the furnace pressure ranges from [4 torr, 5 torr] during the second depressurization stage.

[0156] During the constant-diameter growth process, the furnace pressure is reduced in stages, gradually decreasing from an initial 6-7 torr to 5-6 torr, and finally to 4-5 torr. This is because lower furnace pressure results in a faster argon gas flow rate, which strengthens the purging effect on the melt surface, effectively carrying away silicon oxide gas from the melt and thus reducing the oxygen content in the single-crystal silicon rod. Continuing to reduce the furnace pressure during the constant-diameter stage further enhances this effect, making it suitable for single-crystal silicon rods with extremely high oxygen content requirements.

[0157] Furthermore, in the later stages of constant diameter growth, the melt volume decreases and the liquid level drops, increasing the exposed area of ​​crucible 20 and potentially increasing oxygen release. Gradually reducing the furnace pressure can continuously enhance argon convection, suppress oxygen accumulation, and make the oxygen content of the entire crystal rod more uniform. The staged pressure reduction method allows for a smooth transition, avoiding the impact of sudden pressure changes on the stability of the growth interface, and enhancing the controllability and repeatability of the preparation method. During constant diameter growth, maintaining a constant furnace pressure simplifies the operation process and is suitable for growth scenarios where process stability is paramount.

[0158] The above measures work together to suppress the diffusion of oxygen into the crystal and improve the consistency of crystal quality and resistivity.

[0159] It should also be noted that during the actual crystal pulling process, the pumping speed of the dry pump in the furnace is usually kept constant, and the total amount of gas it carries away is also basically constant. However, the shape of the gas channel 21 directly affects the gas flow rate and local pressure in that area. With the dry pump's pumping volume remaining constant, the larger the gas channel 21, the higher the gas flow rate, and the lower the local pressure in that area. The reduction in local pressure is beneficial for enhancing the carrying effect of argon gas on volatiles (such as silicon monoxide) on the melt surface, promoting their rapid discharge, and thus effectively reducing the oxygen content in the single crystal silicon rod. This application dynamically changes the size of the gas channel 21 through the adjustment mechanism 30, thereby actively reducing the local pressure in the area above the liquid surface of the crucible 20 without increasing the dry pump load. This avoids equipment wear and stability degradation caused by long-term high-load operation of the dry pump, and provides a reliable process control method for continuously obtaining low-oxygen-content, high-quality single crystal silicon rods.

[0160] In step S03, by controlling the movement of the second adjusting member 32, the first adjusting member 31 is driven to restore the preset angle from 0° to the initial angle set during the shoulder-forming stage. This operation resets the position of the adjusting mechanism 30, providing the same initial state for the next crystal pulling cycle, which helps maintain the consistency of parameters between multiple process cycles and supports the repeatability and long-term stable production of the preparation process.

[0161] It should be noted that the above steps can be adjusted and combined. The parameter settings for each stage (such as initial angle, adjustment rate, argon flow range, furnace pressure value, etc.) can be selected within the range given in the corresponding embodiments to achieve coordinated control of the gas channel 21 morphology, argon flow rate and furnace pressure, thereby supporting the stable preparation of high-quality, low-oxygen-content single crystal silicon rods.

[0162] This application provides a silicon wafer cut from a single-crystal silicon rod prepared by the single-crystal silicon rod preparation method in any of the above embodiments.

[0163] The monocrystalline silicon rods prepared by the above-described method have lower oxygen content and fewer defects. Furthermore, the silicon wafers provided in this application are also suitable for the fabrication of photovoltaic cells and photovoltaic modules.

[0164] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0165] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A single crystal furnace, characterized in that, include: A flow guide tube and a crucible, wherein the flow guide tube is located on the top side of the crucible; and The adjustment mechanism includes a first adjustment member and a second adjustment member. One end of the first adjustment member is rotatably connected to the outer side wall of the bottom of the guide tube, and the other end of the first adjustment member is rotatably connected to the second adjustment member. The second adjustment member is configured to move relative to the guide tube in a preset direction, the preset direction being parallel to the direction from the top side of the guide tube to the bottom side of the guide tube.

2. The single crystal furnace according to claim 1, characterized in that, The first adjusting member has a first surface facing the guide tube, the shape of which is adapted to the shape of the outer wall of the guide tube.

3. The single crystal furnace according to any one of claims 1-2, characterized in that, The adjustment mechanism also includes a third adjustment element; One end of the third adjusting member is rotatably connected to the first adjusting member, and the other end of the third adjusting member is rotatably connected to the second adjusting member.

4. The single crystal furnace according to any one of claims 1-2, characterized in that, The outer wall of the bottom of the guide tube includes an inclined section; The first adjusting member is rotatably disposed on the inclined section.

5. The single crystal furnace according to claim 4, characterized in that, The inclined section has a first end close to the crucible and a second end away from the crucible; The angle between the direction from the first end to the second end and the preset direction is the first angle; The first adjusting member is connected to one end of the guide tube, and the direction of the first adjusting member being connected to one end of the second adjusting member, and the angle between the direction of the first end and the direction of the second end is [0°, 45°].

6. The single crystal furnace according to any one of claims 1-2, characterized in that, The first adjusting member is connected to one end of the guide tube, and the direction pointing to the first adjusting member is connected to one end of the second adjusting member, and the angle range between the first adjusting member and the preset direction is [45°, 90°].

7. A method for preparing a single-crystal silicon rod, characterized in that, The method for preparing the single crystal silicon rod using the single crystal furnace as described in any one of claims 1 to 6 includes: During the crystal pulling process, the position of the second adjusting member is controlled to adjust the position of the first adjusting member relative to the guide tube.

8. The preparation method according to claim 7, characterized in that, During the crystal pulling process, controlling the second adjusting member to move along a preset direction to adjust the position of the first adjusting member relative to the guide tube includes: During the shoulder-laying process, the second adjusting member is controlled to be in the first position, while the first adjusting member is kept in the second position; wherein, the end of the first adjusting member connected to the guide tube points in the direction of the end of the first adjusting member connected to the second adjusting member, and the angle formed with the preset direction is the preset angle; the first adjusting member is in the second position, and the preset angle is the initial angle; During the constant diameter growth process, the second adjusting member is controlled to move along the preset direction, so that the preset angle decreases from the initial angle to 0° and remains unchanged until the constant diameter growth process ends.

9. The preparation method according to claim 8, characterized in that, The initial angle is in the range of [75°, 90°]. During the constant diameter growth process, the preset angle is reduced to 0° at a rate of 1° every 10 to 25 minutes.

10. The preparation method according to any one of claims 8-9, characterized in that, The method for preparing the single-crystal silicon rod further includes: During the constant diameter growth process, the argon gas flow rate inside the single crystal furnace is reduced.

11. The preparation method according to claim 10, characterized in that, The reduction of argon flow rate in the single crystal furnace includes a first flow reduction stage, a second flow reduction stage, and a third flow reduction stage executed sequentially. The argon flow rate in the first flow reduction stage is greater than the argon flow rate in the second flow reduction stage, and the argon flow rate in the second flow reduction stage is greater than the argon flow rate in the third flow reduction stage.

12. The preparation method according to any one of claims 8-9, characterized in that, The method for preparing the single-crystal silicon rod further includes: During the constant diameter growth process, the furnace pressure inside the single crystal furnace is reduced; or, During the constant diameter growth process, the furnace pressure is kept constant.

13. The preparation method according to claim 12, characterized in that, The reduction of furnace pressure in the single crystal furnace includes a first pressure reduction stage and a second pressure reduction stage executed sequentially.

14. The preparation method according to any one of claims 8-9, characterized in that, The method for preparing the single-crystal silicon rod further includes: During the cooling process, the second adjusting member is controlled to move along the preset direction, so that the preset angle is adjusted to the initial angle.

15. A silicon wafer, characterized in that, The single crystal silicon rod prepared by the method of any one of claims 7-14 is cut into pieces.

Images