Single crystal furnace and crystal pulling method

Abstract

This disclosure relates to the field of photovoltaic equipment technology, providing a single-crystal furnace and crystal pulling method, which can at least solve problems such as difficulty in controlling oxygen content and significant attenuation of the effect of gas flow on the melt surface. The single-crystal furnace includes: a furnace body and at least two sets of gas conveying components; wherein, a crucible is provided in the furnace body, and a side chamber is formed between the outer peripheral surface of the crucible and the inner wall of the furnace body; at least two sets of gas conveying components are located in the side chamber, and at least two sets of gas conveying components are arranged sequentially along the axial direction of the crucible, wherein the distance between the gas conveying component near the furnace bottom and the gas conveying component near the furnace top is greater than or equal to the upward stroke of the crucible.

Description

Technical Field

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

[0002] The Czochralski method is the mainstream method for preparing solar-grade monocrystalline silicon. With the popularization of N-type cell technology, higher requirements have been placed on the oxygen content of monocrystalline silicon rods. At the same time, under the "dual carbon" goal, reducing the energy consumption of monocrystalline growth has gradually become a core challenge for the industry. Currently, the industry generally adopts the "downward exhaust" furnace type. Since the thermal field direction in the monocrystalline furnace is upward, there is a problem that the main airflow direction is opposite to the natural convection of the thermal field. This easily leads to problems such as: impurity gases such as silicon oxide tend to stay above the melt, making it difficult to control the oxygen content; and as crystal pulling proceeds and the crucible rises, the effect of the airflow on the melt surface is significantly reduced. Summary of the Invention

[0003] This application provides a single crystal furnace and crystal pulling method, which at least helps to solve problems such as difficulty in controlling oxygen content and significant attenuation of the effect of gas flow on the melt surface.

[0004] According to some embodiments of this application, one aspect of this disclosure provides a single crystal furnace, which includes: a furnace body and at least two sets of gas conveying components; wherein, a crucible is provided in the furnace body, and a side chamber is formed between the outer peripheral surface of the crucible and the inner wall of the furnace body; at least two sets of gas conveying components are located in the side chamber, and at least two sets of gas conveying components are arranged sequentially along the axial direction of the crucible, wherein the distance between the gas conveying component near the furnace bottom and the gas conveying component near the furnace top is greater than or equal to the upward stroke of the crucible.

[0005] In some embodiments of this application, each group of gas delivery components includes a nozzle that is inclined toward the bottom of the furnace body, and the angle between the axis of the nozzle and the horizontal plane is the inclination angle of the nozzle; in a first direction, the inclination angle of the nozzle in at least two groups of gas delivery components gradually increases, and the first direction is the direction along the axial direction of the crucible from the bottom of the crucible to the top of the crucible.

[0006] In some embodiments of this application, the gas delivery assembly further includes an annular pipe, which is sleeved on the outside of the crucible, and at least two sets of the annular pipes are arranged sequentially along the axial direction of the crucible; each set of the gas delivery assembly includes at least two nozzles, which are in communication with the annular pipe body, and the at least two nozzles are arranged sequentially along the circumference of the annular pipe body.

[0007] In some embodiments of this application, the annular tube is provided with at least two baffles, which are arranged sequentially along the circumference of the annular tube to divide the internal chamber of the annular tube into at least two flow distribution chambers, and each flow distribution chamber is connected to a nozzle; the gas delivery assembly further includes at least two flow distribution pipes, which are respectively connected to at least two flow distribution chambers, and the flow distribution pipes are used to connect to the gas supply equipment.

[0008] In some embodiments of this application, each of the diversion tubes is provided with a flow regulating valve and a flow sensor. The flow regulating valve is used to regulate the flow rate of the gas in the diversion tube, and the flow sensor is used to detect the flow rate of the gas in the diversion tube.

[0009] In some embodiments of this application, the single crystal furnace further includes a position sensor, a temperature sensor, and a controller. The flow regulating valve, flow sensor, position sensor, and temperature sensor are all electrically connected to the controller. The position sensor is used to detect the position of the crucible. Multiple temperature sensors are provided, and multiple temperature measuring points are provided inside the furnace. The multiple temperature sensors are respectively set at the multiple temperature measuring points, and the temperature sensors are used to detect the temperature at the temperature measuring points. The controller is used to control the flow regulating valve to adjust the flow rate in the split pipe based on the detection signal of at least one of the flow sensor, position sensor, and temperature sensor, or to control at least one of the at least two sets of gas supply components to supply gas or stop gas supply.

[0010] In some embodiments of this application, the furnace body is further provided with a heat-insulating barrel, which is sleeved on the outside of the crucible. The heat-insulating barrel includes an inner wall layer and an outer wall layer that are sleeved on each other. There is a gap between the inner wall layer and the outer wall layer to form an annular airflow channel layer. At least two sets of the gas conveying components are disposed in the annular airflow channel layer.

[0011] In some embodiments of this application, in at least two sets of the gas delivery assemblies, the nozzle tilt angle is 30° to 60°.

[0012] In some embodiments of this application, the furnace body is further provided with a concave reflector, the concave reflector including a concave surface facing the crucible and used to reflect thermal radiation inside the furnace body.

[0013] In some embodiments of this application, the furnace body is further provided with a bottom heater, and the crucible, the bottom heater and the concave reflector are arranged in sequence from top to bottom, with the concave surface facing the bottom heater.

[0014] In some embodiments of this application, the radius of curvature of the concave surface is 300mm~400mm.

[0015] In some embodiments of this application, a first reflective coating is provided on the concave surface, the first reflective coating being used to reflect thermal radiation inside the furnace; and / or, the concave reflective plate is made of a heat-reflective material.

[0016] In some embodiments of this application, the furnace body is further provided with a heat-insulating barrel, which is sleeved on the outside of the crucible. The inner wall of the heat-insulating barrel is provided with a second reflective coating, which is used to reflect the heat radiation inside the furnace body; the concave reflector and the heat-insulating barrel form a heat-reflecting cavity.

[0017] According to some embodiments of this application, another aspect of this disclosure also provides a crystal pulling method, which includes: a loading stage, a melting stage, a crystal pulling stage, a shoulder forming stage, a constant diameter stage, and a finishing stage; wherein, in the crystal pulling stage, the shoulder forming stage, the constant diameter stage, and the finishing stage, the crucible is controlled to rise, and based on the position of the crucible, the gas supply component of at least two sets of gas supply components is controlled to supply gas or stop gas supply, wherein the target gas supply component is one or more of the at least two sets of gas supply components; the gas supply flow rate of the target gas supply component is controlled to be 100-150 slpm.

[0018] In other embodiments of this application, each group of gas delivery components includes at least two flow distribution cavities distributed sequentially along the circumference of the crucible. The crystal pulling method further includes: controlling the gas flow rate in at least one flow distribution cavity of the target gas delivery component to be 50-100 slpm and controlling the gas pressure in at least one flow distribution cavity of the target gas delivery component to be 0.1-0.2 MPa based on at least one of the following information: the position of the crucible, the temperature of the temperature measuring point inside the furnace, and the gas flow rate in each flow distribution cavity.

[0019] The technical solution provided in this disclosure has at least the following advantages: The single-crystal furnace provided in this application is equipped with at least two sets of gas conveying components. These components are arranged sequentially along the axial direction of the crucible. The distance between the uppermost and lowermost gas conveying components along the axial direction is set to be greater than or equal to the crucible's upward stroke, allowing the gas conveying components to adapt to the crucible's movement throughout the entire process. This configuration, with at least two sets of gas conveying components, dynamically enhances blowing based on the crucible's position, compensates for uneven thermal field, and precisely guides silicon oxide gas into the main exhaust duct to reduce oxygen levels. This reduces unit product energy consumption to a specific range and stably controls oxygen content within a specific range. Attached Figure Description

[0020] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures 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 disclosure or the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of a single crystal furnace according to this application; Figure 2 for Figure 1 Sectional view in; Figure 3 for Figure 2 A schematic diagram of the structure of the insulated bucket; Figure 4 for Figure 3 Internal structure diagram; Figure 5 This is a schematic diagram of the connection structure between the annular tube and the nozzle; Figure 6 This is a schematic flowchart of the crystal pulling method in the embodiments of this application.

[0022] Explanation of reference numerals in the attached figures: 1-Furnace body; 2-Crucible; 3-Side chamber; 4-Gas delivery assembly; 5-Nozzle; 6-Annular pipe; 7-Insulation barrel; 8-First air inlet; 9-Second air inlet; 10-First heat exchange screen; 11-Second heat exchange screen; A-First direction. Detailed Implementation

[0023] As the background technology shows, the outer layer of the insulation container in most existing single crystal furnaces is covered with adhesive-based soft felt. Adhesive-based soft felt is a high-purity carbonaceous high-temperature insulating soft felt made from viscose fiber through needle punching, carbonization, and graphitization. Furthermore, the insulation container lacks a bottom reflector. Argon gas is introduced into the single crystal furnace from the top of the auxiliary chamber.

[0024] Therefore, relying on passive insulation materials such as carbon felt cannot effectively block radiative heat loss, especially at the bottom where a "thermal black hole" forms, causing severe energy loss. This results in uneven thermal field, high power consumption, and is prone to causing uneven corrosion of the quartz crucible, becoming a source of oxygen content fluctuations. Furthermore, in downdraft furnaces, the main gas flow conflicts with the natural upward trend of impurities, forming stagnation zones. Existing single crystal furnaces, relying on the main gas flow in the auxiliary chamber, cannot accurately remove oxides from the melt surface, and lack localized fine-tuning methods for the core thermal field.

[0025] In summary, the industry urgently needs a single crystal furnace and crystal pulling method that, through an integrated system solution, can significantly reduce the energy consumption of single crystal growth while effectively controlling the oxygen content of the crystal, adapt to the dynamic process requirements of the entire growth cycle, and improve the thermal stability and crystal quality.

[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. Similarly, "multiple sets" refers to two or more sets (including two sets), and "multiple pieces" refers to two or more pieces (including two pieces).

[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 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," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of 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. Therefore, they should not be construed as limitations on the embodiments of this application. For example, if the device or element in the illustration is inverted, then the element described as "below," "under," "below," or "bottom" of other elements or features will be oriented "above" or "top" of said other elements or features. Therefore, the term "below" may cover both above and below orientation depending on the context in which the term is used, which will be obvious to those skilled in the art. Materials may be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0030] In the description of the embodiments of this application, unless otherwise expressly specified and limited, 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.

[0031] In the description of the embodiments of this application, "electrically connected to one component" means that both components are made of conductive materials, and the two components are in direct contact and connected or connected via other conductive materials, so that current flows between the two components when the photovoltaic module is generating electricity. "Electrically contacting one component to another" means that the two components are not only in contact, but also that, since both components are made of conductive materials, current flows between the two components when the photovoltaic module is generating electricity.

[0032] In the description of embodiments of this application, the terms "about," "approximately," "roughly," or "about" for a numerical value referring to a specific parameter include the numerical value, and those skilled in the art will understand that the deviation from the numerical value is within the acceptable tolerance of the specific parameter. For example, "about" or "about" for a numerical value may include additional numerical values ​​that are in the range of 90.0% to 110.0% of the numerical value, such as in the range of 95.0% to 105.0%, 97.5% to 102.5%, 99.0% to 101.0%, 99.5% to 100.5%, or 99.9% to 100.1%.

[0033] In the accompanying drawings corresponding to the embodiments of this application, the thickness and / or area of ​​layers, films, panels, regions, etc., are enlarged for better understanding and ease of description. Throughout the specification, the same reference numerals denote the same elements. 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.

[0034] In the description of embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and may be further included. 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 an intermediate component between the two components. Conversely, when describing a component on the surface of another component, or a component "directly" on another component, or a component surface on which another component is formed or disposed, it indicates that there is no intermediate component between the two components. For simplicity and clarity, various components may be drawn at any scale. In the drawings, some components may be omitted for simplicity.

[0035] 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 "the component" is also intended to include the plural form unless the context clearly indicates otherwise.

[0036] The “components” mentioned above can refer to layers, membranes, regions, parts, plates, or structures, etc.

[0037] The embodiments of this disclosure 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 disclosure to facilitate a better understanding of the disclosure. However, the technical solutions claimed in this disclosure can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0038] This application provides a single crystal furnace, which can be a Czochralski type single crystal furnace or the like. The single crystal furnace can be used to prepare single crystal silicon rods. Some embodiments of the single crystal furnace provided in this application are shown in the figure.

[0039] Please see Figures 1-6 In some embodiments, the single crystal furnace includes: a furnace body 1 and at least two sets of gas conveying components 4; wherein, a crucible 2 is provided inside the furnace body 1, and a side chamber 3 is formed between the outer peripheral surface of the crucible 2 and the inner wall of the furnace body 1; at least two sets of gas conveying components 4 are located in the side chamber 3, and at least two sets of gas conveying components 4 are arranged sequentially along the axial direction of the crucible 2, and the distance between the gas conveying component 4 near the furnace bottom and the gas conveying component 4 near the furnace top is greater than or equal to the upward stroke of the crucible 2.

[0040] For example, the single crystal furnace includes a furnace body 1, and a crucible 2 is installed inside the furnace body 1. The axial direction of the crucible 2 is parallel or nearly parallel to the axial direction of the furnace body 1, that is, the axial direction of the crucible 2 extends vertically. The crucible 2 can be connected to the inner bottom surface of the single crystal furnace via a drive structure, and the crucible 2 can be controlled to move along the axial direction of the single crystal furnace by the drive mechanism. A side chamber 3 is formed between the outer peripheral surface of the crucible 2 and the inner sidewall of the furnace body 1, through which gas inside the furnace body 1 can circulate.

[0041] In another example, the single crystal furnace includes at least two sets of gas supply components 4. For example, it may include six, seven, or eight sets of gas supply components 4. In this embodiment, the number of gas supply components 4 is not specifically limited and can be set according to the actual situation. This embodiment uses eight sets of gas supply components 4 as an example for explanation and illustration. The structures of the eight sets of gas supply components 4 are similar.

[0042] Among them, eight gas conveying components 4 are arranged at intervals along the axial direction of the crucible 2. The distance between the gas conveying components 4 near the top of the furnace and the gas conveying components 4 near the bottom of the furnace is greater than or equal to the upward stroke of the crucible 2. That is, the eight gas conveying components 4 can fully cover the upward stroke of the crucible 2, thereby blowing the crucible 2 at different heights.

[0043] In the above embodiment, at least two sets of gas conveying components 4 are sequentially arranged along the axial direction of the crucible 2. Furthermore, the distance between the uppermost and lowermost gas conveying components 4 along the axial direction is set to be greater than or equal to the upward stroke of the crucible 2, allowing the gas conveying components 4 to adapt to the movement of the crucible 2 throughout its movement. This arrangement, with at least two sets of gas conveying components 4, allows for dynamic enhancement of blowing based on the position of the crucible 2, compensation for uneven thermal field, and precise guidance of silica gas into the main exhaust duct to reduce oxygen levels. This reduces the energy consumption per unit product to a specific range and stably controls the oxygen content within a specific range.

[0044] In some embodiments of this application, each gas delivery assembly 4 includes a nozzle 5, the nozzle 5 is inclined toward the bottom of the furnace body 1, and the angle between the axis of the nozzle 5 and the horizontal plane is the inclination angle of the nozzle 5; in the first direction A, the inclination angle of the nozzle 5 in at least two gas delivery assemblies 4 gradually increases, the first direction A is the direction along the axial direction of the crucible 2 from the bottom of the crucible 2 to the top of the crucible 2.

[0045] For example, taking eight gas delivery assemblies 4 as an example, each gas delivery assembly 4 is provided with a nozzle 5. The opening direction of the nozzle 5 is inclined towards the bottom of the furnace body 1, that is, there is an angle between the axial direction of the nozzle 5 opening and the horizontal plane. This angle can be understood as the tilt angle of the nozzle 5. The tilt angle of the nozzle 5 on different gas delivery assemblies 4 is different. Among them, along the axial direction of the crucible 2 from the bottom of the crucible 2 to the top of the crucible 2, the tilt angle of the nozzle 5 gradually increases.

[0046] For example, the nozzles 5 on the group of gas conveying components 4 closest to the furnace bottom are tilted downwards at an angle of approximately 30°. Along the axial direction from the furnace bottom to the furnace top, the nozzles 5 on the fourth group of gas conveying components 4 are tilted downwards at an angle of approximately 45°, and the nozzles 5 on the group of gas conveying components 4 closest to the furnace top are tilted downwards at an angle of approximately 60°-65°. For example, the tilt angles can be 60°, 61°, 62°, 63°, 64°, 65°, etc. The downward tilt angles of the nozzles 5 on the other groups of gas conveying components 4 can be set according to the angles of the bottommost, fourth, and topmost groups of nozzles 5 mentioned above, increasing sequentially from bottom to top. Furthermore, in this embodiment, the tilt angle of the nozzles 5 on each group of gas conveying components 4 is not specifically limited, but is set according to the actual situation.

[0047] In the above embodiments, the multiple sets of gas delivery components 4 can cover the entire journey of the crucible 2 from its initial position to its apex, and the tilt angle of the nozzles 5 on each set of gas delivery components 4 increases from top to bottom, ensuring that the nozzles 5 activated at different stages can always guide the gas flow to the surface of the melt at a better angle.

[0048] In some embodiments of this application, the gas delivery assembly 4 further includes an annular pipe 6, which is sleeved on the outside of the crucible 2, and at least two sets of annular pipes 6 are arranged sequentially along the axial direction of the crucible 2; each set of gas delivery assembly 4 includes at least two nozzles 5, which are in communication with the body of the annular pipe 6, and at least two nozzles 5 are arranged sequentially along the circumference of the body of the annular pipe 6.

[0049] The annular pipe 6 is provided with at least two baffles, which are arranged sequentially along the circumference of the annular pipe 6 to divide the internal chamber of the annular pipe 6 into at least two flow chambers. Each flow chamber is connected to a nozzle 5. The gas delivery assembly 4 also includes at least two flow pipes, which are respectively connected to at least two flow chambers. The flow pipes are used to connect to the gas supply equipment.

[0050] For example, taking eight sets of gas delivery components 4 as an example, each set of gas delivery components 4 is provided with an annular pipe 6, and the interior of the annular pipe 6 is a hollow structure. The annular pipe 6 is sleeved on the outside of the crucible 2, and the eight annular pipes 6 are arranged sequentially at intervals along the axial direction of the crucible 2. In this embodiment of the application, the distance between two adjacent annular pipes 6 is not specifically limited, and is set according to the actual situation.

[0051] Each annular tube 6 is provided with at least two nozzles 5, such as three, four, or five, taking eight nozzles 5 as an example; the openings of all eight nozzles 5 are connected to the annular tube 6, that is, the gas inside the annular tube 6 can be ejected through the nozzles 5, and the eight nozzles 5 are arranged at intervals along the circumference of the annular tube 6. In this embodiment of the application, the number of nozzles 5 and the spacing between two adjacent nozzles 5 are not specifically limited, and are set according to the actual situation.

[0052] In another example, each annular tube 6 is provided with eight baffles, which are distributed at intervals along the circumference of the annular tube 6. The eight baffles divide the interior of the annular tube 6 into eight flow chambers, each of which is connected to a nozzle 5. Each flow chamber is also connected to a flow pipe, which is connected to a gas supply device. The gas supply device delivers the gas to the corresponding space, and then it is ejected through the nozzle 5 in the corresponding space.

[0053] It is understood that each branch pipe can be connected to a separate gas supply device; alternatively, multiple branch pipes can be connected to the same gas supply device, which can supply gas to one or more branch pipes. In this embodiment, the number of baffles is not specifically limited, and the number of baffles corresponds to the number of nozzles 5; similarly, the number of gas supply devices is not specifically limited and can be set according to actual conditions.

[0054] In the above embodiment, the multiple nozzles 5 can eject gas from outside the crucible 2 at different positions in the circumferential direction. Compared to a single nozzle 5, which can only eject gas from a fixed position, this arrangement improves the uniformity of the ejected gas. The eight flow-dividing chambers and eight nozzles 5 correspond one-to-one, allowing for individual control of each nozzle 5, thereby achieving precise control of a specific nozzle 5.

[0055] In some embodiments of this application, each branch pipe is equipped with a flow regulating valve and a flow sensor. The flow regulating valve is used to regulate the flow rate of gas in the branch pipe, and the flow sensor is used to detect the flow rate of gas in the branch pipe. The single crystal furnace also includes a position sensor, a temperature sensor, and a controller. The flow regulating valve, flow sensor, position sensor, and temperature sensor are all electrically connected to the controller. The position sensor is used to detect the position of the crucible 2. Multiple temperature sensors are provided, and multiple temperature measuring points are provided inside the furnace body 1. Multiple temperature sensors are respectively set at multiple temperature measuring points, and the temperature sensors are used to detect the temperature at the measuring points. The controller is used to control the flow regulating valve to regulate the flow rate in the branch pipe based on the detection signal of at least one of the flow sensor, position sensor, and temperature sensor, or to control at least one of the at least two sets of gas supply components 4 to supply gas or stop gas supply.

[0056] For example, each manifold is equipped with a flow regulating valve and a flow sensor; the flow rate of the gas in the manifold is regulated by the flow regulating valve, and the flow rate of the gas in the manifold is detected by the flow sensor.

[0057] In another example, the single crystal furnace is also equipped with a position sensor, a temperature sensor, and a controller. The flow regulating valve, the position sensor, and the temperature sensor are all electrically connected to the controller. The position sensor and / or the temperature sensor transmit signals to the controller, which controls the opening and closing of the flow regulating valve.

[0058] The position sensor is installed on the side wall of the furnace body 1 at a position corresponding to the crucible 2. The position sensor detects the position of the crucible 2 and transmits this information to the controller, allowing for the automatic selection of the gas delivery component 4 to be activated based on the crucible 2's position. Multiple temperature sensors can be configured, corresponding to multiple temperature measurement points within the furnace body 1. Each temperature measurement point corresponds to a specific temperature sensor, which is installed at the designated measurement point to detect the temperature at that point.

[0059] Furthermore, the controller can control the opening and closing of the flow regulating valve and control the flow rate in the diverter pipe based on detection signals from one or more of the flow sensor, position sensor, and temperature sensor. Alternatively, it can control at least one of the eight gas delivery components 4 to deliver or stop gas delivery.

[0060] In the above embodiments, when the crucible 2 rises and the system automatically switches from the low-position nozzle 5 to the high-position nozzle 5, the argon supply flow rate and pressure of that row of nozzles 5 are simultaneously increased according to a preset model. For example, the flow rate increase can reach 20%-100%, such as 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, etc. In this embodiment, the value of the flow rate increase is not specifically limited and is set according to the actual situation. This setting can accurately compensate for the gas flow rate attenuation caused by the increase in the vertical distance between the nozzle 5 and the melt surface, achieving the effect of "rising melt surface without diminishing blowing effect," thereby solving the problem of gas flow failure in the later stages of crystal growth.

[0061] Furthermore, each branch pipe is equipped with multiple branch chambers, each with an independent flow regulating valve and sensor, which can be independently programmed and controlled by the control system. This configuration allows the system to fine-tune the airflow in specific locations based on real-time feedback from the thermal field temperature measurement points, in order to compensate for circumferential non-uniformity of the thermal field or to respond to local disturbances caused by operations such as feeding or observation, achieving smooth "pixel-level" fine management.

[0062] Furthermore, the position sensor can receive signals from the crucible 2 position encoder, calculate in real time, and automatically activate the 1-3 rows of "optimal" nozzles 5 closest to the current melt surface. Through a multivariate coordination algorithm, information such as the crucible 2 position and growth stage is integrated to dynamically optimize the total flow rate, pressure, and flow distribution ratio of each activated row, as well as each zone. This ensures that the airflow control strategy matches the thermal state of the reflective thermal field, avoiding negative interference to the thermal field stability caused by excessive or uneven airflow, and achieving positive synergy between the two subsystems.

[0063] In some embodiments of this application, the furnace body 1 is further provided with a heat preservation barrel 7, which is sleeved on the outside of the crucible 2. The heat preservation barrel 7 includes an inner wall layer and an outer wall layer that are sleeved on each other. There is a gap between the inner wall layer and the outer wall layer to form an annular airflow channel layer. At least two sets of gas conveying components 4 are disposed in the annular airflow channel layer.

[0064] For example, a heat preservation barrel 7 is provided inside the furnace body 1. The heat preservation barrel 7 can be configured to include an inner wall layer and an outer wall layer. Both the inner wall layer and the outer wall layer are fitted onto the outer wall of the crucible 2, and the outer wall layer is fitted onto the outer side of the inner wall layer. That is, the inner wall layer is located between the outer wall layer and the crucible 2. There is a gap between the outer wall layer and the inner wall layer. This gap forms an annular airflow channel layer. Multiple sets of gas conveying components 4 are placed inside the annular airflow channel layer.

[0065] In another example, a concave reflector is also provided inside the furnace body 1. The concave reflector has a concave surface facing the crucible 2 and is installed inside the furnace body 1 to reflect the heat radiation inside the furnace body 1. In addition, a bottom heater is also provided inside the furnace body 1. Along the axial direction of the crucible 2, the crucible 2, the bottom heater, and the concave reflector are arranged sequentially from top to bottom, with the concave surface of the concave reflector facing the bottom heater.

[0066] The radius of curvature of the concave surface can be 300mm-400mm, for example, it can be 300mm, 310mm, 320mm, 330mm, 340mm, 350mm, 360mm, 370mm, 380mm, 390mm, 400mm, etc. In this embodiment, the radius of curvature of the concave surface is not specifically limited and can be set according to actual conditions. A first reflective coating can also be applied to the concave surface to reflect the heat radiation inside the furnace body 1. And / or, the concave reflector can be made of heat-reflective material.

[0067] In another example, a second reflective coating can be provided on the inner wall of the heat-insulating barrel 7 to reflect the heat radiation inside the furnace body 1. The concave reflector and the heat-insulating barrel 7 enclose a heat-reflecting cavity.

[0068] Accordingly, another embodiment of this disclosure also provides a crystal pulling method, which can prepare solar-grade monocrystalline silicon using the monocrystalline furnace provided in the above embodiments. The manufacturing method of the crystal pulling method provided in another embodiment of this disclosure will be described in detail below with reference to the accompanying drawings. For parts that are the same as or corresponding to the previous embodiment, please refer to the corresponding descriptions of the foregoing embodiments; detailed descriptions will not be repeated below.

[0069] Specifically, the crystal pulling method is divided into six major processes: charging, melting, crystal pulling, shoulder forming, equal diameter forming, and finishing. Based on at least one of the following information: the position of the crucible 2, the temperature of the temperature measuring point inside the furnace 1, and the gas flow rate in each branch cavity, the gas flow rate in at least one branch cavity of one or more gas conveying components 4 is controlled to compensate for uneven thermal field, reduce the energy consumption per unit product to a specific range, and stably control the oxygen content within a specific range.

[0070] During the charging stage: the first heat exchange screen 10 and the second heat exchange screen 11 are raised to their upper limit positions to fully expand the visible space inside the furnace, ensuring a clear and unobstructed real-time observation view inside the furnace, which facilitates the accurate completion of silicon material filling operations; at the same time, the furnace body 1 is slowly and gradually heated to effectively avoid the sudden heat absorption of low-temperature components inside the furnace, which can generate thermal stress, prevent the equipment welds from cracking and breaking due to uneven thermal expansion and contraction, and ensure the integrity of the equipment structure and the stability of the operating conditions in the early stage of production.

[0071] Melting Stage: The melting stage mainly involves heating and melting the silicon material. The molten silicon surface fluctuates greatly, and there are many volatiles, making it easy for oxygen-containing impurities to enter the furnace. Therefore, the air flow rates at both the first air inlet 8 and the second air inlet 9 are controlled at 50 LPM-70 LPM. This dual-path synchronous medium-volume gas supply quickly replaces the existing air in the furnace, rapidly establishing a stable protective atmosphere, effectively suppressing oxygen intrusion, and simultaneously quickly removing volatile impurities generated during the melting process, creating a clean furnace environment for subsequent crystal growth.

[0072] Before crystal growth begins in the melting stage, the first heat exchanger 10 and the second heat exchanger 11 mainly play the role of airflow guidance. They can accurately guide the protective gas directly to the surface of the silicon liquid, greatly improving the efficiency of the protective gas in purging and removing oxide impurities on the liquid surface, efficiently removing oxides generated during the melting process, and purifying the growth atmosphere inside the furnace.

[0073] During the melting stage, the air flow rate of the first air inlet 8 can be 50 LPM, 51 LPM, 52 LPM, 53 LPM, 54 LPM, 55 LPM, 56 LPM, 57 LPM, 58 LPM, 59 LPM, 60 LPM, 61 LPM, 62 LPM, 63 LPM, 64 LPM, 65 LPM, 66 LPM, 67 LPM, 68 LPM, 69 LPM, or 70 LPM. The air flow rate of the second air inlet 9 can be 50 LPM, 51 LPM, 52 LPM, 53 LPM, 54 LPM, 55 LPM, 56 LPM, 57 LPM, 58 LPM, 59 LPM, 60 LPM, 61 LPM, 62 LPM, 63 LPM, 64 LPM, 65 LPM, 66 LPM, 67 LPM, 68 LPM, 69 LPM, or 70 LPM.

[0074] Crystal growth, shoulder formation, and equal diameter stages: After entering the formal crystal growth stage, the crystal morphology gradually takes shape. It is necessary to strengthen the protection of the main airflow and appropriately weaken the auxiliary gas supply. Therefore, the airflow of the first air inlet 8 is set to 80 LPM~90 LPM to increase the main air volume and form a stable mainstream gas curtain from top to bottom, which closely adheres to the outer wall of the crystal rod to form an isolation barrier. The airflow of the second air inlet 9 is adjusted to 30 LPM~40 LPM, with small flow auxiliary gas supply as the main method. This not only fills the local airflow gaps but also avoids the auxiliary airflow from disturbing the main airflow direction, ensuring a stable and orderly airflow during the crystal growth process.

[0075] During the crystal pulling, shoulder formation, and equal diameter stages, the airflow rate of the first air inlet 8 can be 80 LPM, 81 LPM, 82 LPM, 83 LPM, 84 LPM, 85 LPM, 86 LPM, 87 LPM, 88 LPM, 89 LPM, or 90 LPM, etc. The airflow rate of the second air inlet 9 can be 30 LPM, 31 LPM, 32 LPM, 33 LPM, 34 LPM, 35 LPM, 36 LPM, 37 LPM, 38 LPM, 39 LPM, or 40 LPM, etc.

[0076] Shoulder Formation Stage: During the shoulder formation stage, the crystal diameter gradually expands, and the crystal form is in a critical transition period. Higher requirements are placed on the stability of the thermal and flow fields. At this time, the airflow rates at the first inlet 8 and the second inlet 9 are simultaneously reduced to slow the airflow velocity and decrease the impact and disturbance of the airflow on the nascent crystal. This effectively avoids problems such as crystal form distortion and lattice disorder caused by airflow impact, ensuring a regular and smooth shoulder formation and a stable transition to the constant-diameter growth stage. As the crystal rod leaves the heat exchanger area, the airflow rates at the first inlet 8 and the second inlet 9 are gradually reduced to zero.

[0077] During the crystal pulling stage, shoulder formation stage, equal diameter stage, and finishing stage, the crucible 2 is controlled to rise. Based on the position of the crucible 2, one or more of the at least eight gas conveying components 4 are controlled to supply gas or stop gas supply. The gas flow rate of one or more gas conveying components 4 is controlled to be 100-150 slpm, for example, the gas flow rate can be 100 slpm, 110 slpm, 120 slpm, 130 slpm, 140 slpm, 150 slpm, etc. Meanwhile, each gas delivery assembly 4 includes at least two flow distribution cavities distributed sequentially along the circumference of the crucible 2; the crystal pulling method further includes: controlling the gas flow rate in at least one flow distribution cavity of one or more gas delivery assemblies 4 to be 50-100 slpm based on at least one of the following information: the position of the crucible 2, the temperature of the temperature measuring point inside the furnace 1, and the gas flow rate in each flow distribution cavity; for example, the gas flow rate can be 50 slpm, 60 slpm, 70 slpm, 80 slpm, 90 slpm, 100 slpm, etc.; controlling the gas pressure in at least one flow distribution cavity of one or more gas delivery assemblies 4 to be 0.1-0.2 MPa; for example, the gas pressure can be 0.1 MPa, 0.11 MPa, 0.12 MPa, 0.13 MPa, 0.14 MPa, 0.15 MPa, 0.16 MPa, 0.17 MPa, 0.18 MPa, 0.19 MPa, 0.2 MPa, etc.

[0078] It needs to be explained that during the melting stage, high-power heating can be used to completely melt the silicon material; during the crystallization stage, the temperature can be fine-tuned to find the critical crystallization temperature. Taking the melting point of silicon as an example, which is 1412℃, the critical crystallization temperature is slightly higher than the melting point; during the constant diameter stage, heat dissipation is compensated by slowly reducing the power to maintain the stability of the solid-liquid interface. The melt temperature is generally controlled between 1415-1430℃. For example, the melt temperature can be 1415℃, 1416℃, 1417℃, 1418℃, 1419℃, 1420℃, 1421℃, 1422℃, 1423℃, 1424℃, 1425℃, 1426℃, 1427℃, 1428℃, 1429℃, 1430℃, etc. The melt temperature can be the necessary temperature difference at the solid-liquid interface, typically 2-8℃, for example, 2℃, 3℃, 4℃, 5℃, 6℃, 7℃, 8℃, etc. Too low a temperature promotes polycrystalline growth, while too low a temperature leads to slow crystal growth. Furthermore, during the crystallization stage, the crystal rotation speed can be controlled at 8-15 rpm, for example, 8 rpm, 9 rpm, 10 rpm, 11 rpm, 12 rpm, 13 rpm, 14 rpm, 15 rpm, etc. During the shoulder-forming and diameter-constraining stages, the crystal rotation speed can be controlled at 12-16 rpm, for example, 12 rpm, 13 rpm, 14 rpm, 15 rpm, 16 rpm, etc. The crucible rotation direction is generally opposite to the crystal rotation direction, typically 2-8 rpm, for example, 2 rpm, 3 rpm, 4 rpm, 5 rpm, 6 rpm, 7 rpm, 8 rpm, etc.

[0079] In addition, during the crystal pulling stage, the crystal pulling speed can be controlled between 1.8-3.0 mm / min, for example, 1.8 mm / min, 1.9 mm / min, 2.1 mm / min, 2.2 mm / min, 2.3 mm / min, 2.4 mm / min, 2.5 mm / min, 2.6 mm / min, 2.7 mm / min, 2.8 mm / min, 2.9 mm / min, 3.0 mm / min, etc.; during the shoulder formation stage, the pulling speed is gradually reduced to 1.2-2.2 mm / min, for example, 1.2 mm / min, 1.3 mm / min, 1.4 mm / min, 1.5 mm / min, 1.6 mm / min, 1.7 mm / min, 1.8 mm / min, 1.9 mm / min, 2.0 mm / min, 2.1 mm / min, 2.2 mm / min, etc. For example, during the constant diameter growth stage, if the single crystal rod diameter is 8 inches, the pulling speed should be controlled between 1.2 and 2.2 mm / min, for example, 1.2 mm / min, 1.3 mm / min, 1.4 mm / min, 1.5 mm / min, 1.6 mm / min, 1.7 mm / min, 1.8 m / min, 1.9 mm / min, 2.0 mm / min, 2.1 mm / min, 2.2 mm / min, etc. If the diameter is 12 inches, the pulling speed should be controlled between 0.6 and 1.2 mm / min, for example, 0.6 mm / min, 0.7 mm / min, 0.8 mm / min, 0.9 mm / min, 1.0 mm / min, 1.1 mm / min, 1.2 m / min, etc. In the final stage, the pulling speed should be gradually increased and the crystal diameter reduced to decrease the probability of crystallization cracking.

[0080] Furthermore, during the heating and melting stage, the power of the main heater can be 110-155KW, for example, 110KW, 120KW, 130KW, 140KW, 150KW, etc.; after all the silicon material has melted, the power is gradually reduced to 95-120KW, for example, 95KW, 100KW, 105KW, 110KW, 115KW, 120KW, etc.; during the crystal pulling stage, the power of the main heater can be 85-105KW, for example, 85KW, 90KW, 95KW, 100KW, 105KW, etc.; during the shoulder formation stage, the power of the main heater can be 75-95KW, for example, 75KW, 80KW, 85KW, etc. 90KW, 95KW, etc.; Equal diameter growth stage: The heating power at the beginning of equal diameter growth can be 70-88KW, for example, 75KW, 80KW, 85KW, etc.; The heating power in the middle of equal diameter growth can be 55-72KW, for example, 55KW, 60KW, 65KW, 70KW, etc.; The heating power in the later stage of equal diameter growth can be 42-58KW, for example, 42KW, 50KW, 55KW, etc.; In the final stage, the power is slightly increased again by 3-10KW, for example, 3KW, 4KW, 5KW, 6KW, 7KW, 8KW, 9KW, 10KW, etc.; At the same time, the pulling speed is increased to shrink the crystal diameter and reduce the probability of crystal breakage.

[0081] Those skilled in the art will understand that the above embodiments are specific examples of implementing this disclosure, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of this disclosure. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this disclosure; therefore, the scope of protection of this disclosure should be determined by the scope defined in the claims.

Claims

1. A single crystal furnace, characterized in that, include: A furnace body, wherein a crucible is provided inside the furnace body, and a side chamber is formed between the outer peripheral surface of the crucible and the inner wall of the furnace body; At least two sets of gas conveying components are provided, both of which are located in the side chamber and are arranged sequentially along the axial direction of the crucible. The distance between the gas conveying component near the bottom of the furnace and the gas conveying component near the top of the furnace is greater than or equal to the upward stroke of the crucible.

2. The single crystal furnace according to claim 1, characterized in that, Each of the gas delivery components includes a nozzle that is inclined toward the bottom of the furnace body, and the angle between the axis of the nozzle and the horizontal plane is the inclination angle of the nozzle. In a first direction, the tilt angle of the nozzles in at least two sets of gas delivery assemblies gradually increases, the first direction being the direction along the axial direction of the crucible from the bottom of the crucible to the top of the crucible.

3. The single crystal furnace according to claim 1 or 2, characterized in that, The gas delivery assembly also includes an annular pipe, which is sleeved on the outside of the crucible, and at least two sets of the annular pipes are arranged sequentially along the axial direction of the crucible. Each gas delivery assembly includes at least two nozzles, both of which are in communication with the annular pipe, and the at least two nozzles are arranged sequentially along the circumference of the annular pipe.

4. The single crystal furnace according to claim 3, characterized in that, The annular tube is provided with at least two baffles, which are arranged sequentially along the circumference of the annular tube to divide the internal chamber of the annular tube into at least two flow-diverting chambers, and each flow-diverting chamber is connected to a nozzle; The gas delivery assembly further includes at least two branch pipes, each of which is connected to at least two branch cavities. The branch pipes are used to connect to the gas supply equipment.

5. The single crystal furnace according to claim 4, characterized in that, Each of the diverter tubes is equipped with a flow regulating valve and a flow sensor. The flow regulating valve is used to regulate the flow rate of the gas in the diverter tube, and the flow sensor is used to detect the flow rate of the gas in the diverter tube.

6. The single crystal furnace according to claim 5, characterized in that, The single crystal furnace also includes a position sensor, a temperature sensor, and a controller, and the flow regulating valve, flow sensor, position sensor, and temperature sensor are all electrically connected to the controller; The position sensor is used to detect the position of the crucible; The furnace body is provided with multiple temperature sensors and multiple temperature measuring points. The multiple temperature sensors are respectively set at the multiple temperature measuring points, and the temperature sensors are used to detect the temperature at the temperature measuring points. The controller is used to control the flow regulating valve to adjust the flow rate in the diverter pipe based on the detection signal of at least one of the flow sensor, position sensor and temperature sensor, or to control at least one of the at least two sets of gas delivery components to deliver or stop gas delivery.

7. The single crystal furnace according to claim 4, characterized in that, The furnace body is also provided with a heat preservation barrel, which is sleeved on the outside of the crucible. The heat preservation barrel includes an inner wall layer and an outer wall layer that are sleeved on each other. There is a gap between the inner wall layer and the outer wall layer to form an annular airflow channel layer. At least two sets of the gas conveying components are disposed in the annular airflow channel layer.

8. The single crystal furnace according to claim 2, characterized in that, In at least two of the aforementioned gas delivery assemblies, the nozzle tilt angle is 30° to 60°.

9. The single crystal furnace according to claim 1, characterized in that, The furnace body is also provided with a concave reflector plate, which includes a concave surface facing the crucible and used to reflect the thermal radiation inside the furnace body.

10. The single crystal furnace according to claim 9, characterized in that, The furnace body is also equipped with a bottom heater. The crucible, the bottom heater and the concave reflector are arranged in sequence from top to bottom, with the concave surface facing the bottom heater.

11. The single crystal furnace according to claim 9, characterized in that, The radius of curvature of the concave surface is 300mm~400mm.

12. The single crystal furnace according to claim 9, characterized in that, The concave surface is provided with a first reflective coating, which is used to reflect the thermal radiation inside the furnace. And / or, the concave reflector is made of a heat-reflective material.

13. The single crystal furnace according to claim 9, characterized in that, The furnace body is also equipped with a heat preservation barrel, which is fitted over the outside of the crucible. The inner wall of the heat preservation barrel is provided with a second reflective coating, which is used to reflect the heat radiation inside the furnace body. The concave reflector and the heat-insulating barrel form a heat-reflecting cavity.

14. A crystal pulling method, characterized in that, For a single crystal furnace as described in any one of claims 1 to 13, the crystal pulling method includes a charging stage, a melting stage, a crystal pulling stage, a shoulder forming stage, a constant diameter stage, and a finishing stage; During the crystal pulling stage, shoulder forming stage, equal diameter stage, and finishing stage, the crucible is controlled to rise. Based on the position of the crucible, the target gas conveying component in at least two gas conveying components is controlled to convey gas or stop conveying gas. The target gas conveying component is one or more of the at least two gas conveying components. The gas flow rate of the target gas delivery component is controlled to be 100-150 slpm.

15. The crystal pulling method according to claim 14, characterized in that, Each gas delivery assembly includes at least two flow distribution cavities sequentially distributed along the circumference of the crucible, and the crystal pulling method further includes: Based on at least one of the following information: the position of the crucible, the temperature of the temperature measuring point inside the furnace, and the gas flow rate in each branch chamber, the gas flow rate in at least one branch chamber of the target gas delivery assembly is controlled to be 50-100 slpm, and the gas pressure in at least one branch chamber of the target gas delivery assembly is controlled to be 0.1-0.2 MPa.

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