Single crystal furnace

Abstract

The invention discloses a single crystal furnace. The single crystal furnace comprises: a thermal insulation cylinder, the top of which is provided with a mounting port and the bottom of which is provided with a first gas outlet; the crucible edge is movably arranged in the heat preservation cylinder in the vertical direction, and the top of the crucible edge is open; the guide cylinder assembly is arranged at the mounting opening and located on the upper side of the crucible side, a first air inlet is formed in the top of the guide cylinder assembly, and the lower end of the guide cylinder assembly is located on the inner circumferential side of the crucible side and communicated with the crucible side; the heater is arranged in the heat preservation cylinder and surrounds the crucible edge, the heater and the crucible edge are spaced to define an annular flow channel, and the annular flow channel is communicated with the first air outlet; the gas sealing ring is mounted at the upper end of the crucible edge, and the gas sealing ring comprises an annular plate. Therefore, the oxygen-containing gas can be guided, the dissipation space of the oxygen-containing gas is reduced, the discharge rate of the oxygen-containing gas is increased, and the oxygen content in the single crystal furnace is further reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of single crystal furnace, in particular to a single crystal furnace. BACKGROUND

[0002] At present, N-type single crystal becomes the core product of photovoltaic industry production, is the hope of the battery end to pursue the ultimate efficiency, and is the inevitable choice of technical direction. However, the yield of N-type single crystal is accompanied by the exposure of its shortcomings, that is, the requirement for oxygen content is more demanding, the generation rate of oxygen precipitation concentric circle caused by oxygen in N-type single crystal increases obviously, and the oxygen precipitation concentric circle will affect the minority carrier lifetime of single crystal silicon wafer, and then affect the conversion efficiency and yield of the battery. Therefore, reducing the oxygen content of N-type single crystal is a difficult problem to be solved.

[0003] The following two schemes are generally used in the industry to reduce the oxygen content in the single crystal furnace: One is to add a deoxygenation ring, and cooperate with shortening the length of the heater heating area, reduce the temperature at the bottom of the crucible, and reduce the oxygen precipitation rate, so as to realize the reduction of product oxygen content. However, the installation position of the deoxygenation ring and the deoxygenation technology of the heating area have reached the limit of the existing technology, which has obviously restricted the effect of further reducing the oxygen content.

[0004] The second is to adjust the shape of the flow guide cylinder. However, the structure point of the flow guide cylinder affecting the oxygen content is too close to the liquid surface of the crucible, which limits the airflow distribution and reduces the oxygen carrying efficiency.

[0005] Therefore, the above two schemes have very limited effect on reducing the oxygen content of N-type single crystal, and need to be further improved. SUMMARY

[0006] Therefore, the present application provides a single crystal furnace which can guide the oxygen-containing gas, reduce the escape space of the oxygen-containing gas, accelerate the discharge rate of the oxygen-containing gas, and thus reduce the oxygen content in the single crystal furnace.

[0007] To achieve the above objectives, the present invention proposes a single crystal furnace, comprising: a heat-insulating cylinder having an installation port at the top and a first air outlet at the bottom; a crucible assembly movably disposed within the heat-insulating cylinder in a vertical direction, the top of the crucible assembly being open; a flow guide assembly disposed at the installation port, the flow guide assembly being located on the upper side of the crucible assembly, the top of the flow guide assembly having a first air inlet, the lower end of the flow guide assembly being located on the inner circumference of the crucible assembly and communicating with the crucible assembly; and a heater disposed within the heat-insulating cylinder and surrounding the crucible assembly. The heater is spaced apart from the crucible to define an annular flow channel, which communicates with the first air outlet. A sealing ring is installed at the upper end of the crucible and includes an annular plate comprising a first sealing portion located on the inner circumference of the crucible and a second sealing portion located on the outer circumference of the crucible. An exhaust passage is defined between the sealing ring and the upper end of the crucible, or the sealing ring forms an exhaust passage extending through it along the distribution direction of its inner and outer circumferential surfaces. The exhaust passage communicates with the annular flow channel and the interior of the crucible.

[0008] According to the single crystal furnace provided in the embodiments of the present invention, the high-temperature environment inside the insulation cylinder triggers a chemical reaction of oxygen-containing compounds, continuously generating oxygen. When a protective gas (such as argon) is continuously introduced into the insulation cylinder, the gas carries the oxygen and other volatiles generated in the crucible and escapes outward from the gap between the crucible and the guide cylinder assembly. However, due to the restriction of the first sealing part, most of the gas is guided into the exhaust channel by the first sealing part, thereby reducing the probability of direct diffusion to other areas, and thus reducing the amount of oxygen retained in the cavity between the insulation cylinder and the guide cylinder assembly. After the gas flows into the annular flow channel through the exhaust channel, the second sealing part further restricts the airflow path, further reducing the possibility of gas escape, causing the gas to flow downward in a directional manner along the annular flow channel. Finally, the gas is efficiently discharged through the first outlet, forming a continuous gas guiding path of "exhaust channel - annular flow channel - first outlet". By restricting the directional flow of gas, reducing the gas escape area, shortening the residence time and amount of gas in the insulation cylinder, and accelerating the gas discharge rate, the purpose of rapid discharge is achieved, thereby effectively reducing the oxygen content and improving the efficiency of reducing oxygen content.

[0009] In addition, the single crystal furnace proposed in the application may also have the following additional technical features: In one possible implementation of this application, the sealing ring includes: a connecting cylinder connected to the end face of the annular plate facing the crucible and connected to the upper end face of the crucible, wherein the first sealing part and the second sealing part are located on both sides of the connecting cylinder; wherein an exhaust channel is defined between the connecting cylinder and the upper end face of the crucible, or the connecting cylinder forms the exhaust channel.

[0010] In one possible implementation of this application, the crucible has a lower limit position, in which, along the vertical direction, the annular plate is located between the upper end of the heater and the lower end of the guide tube assembly; in the direction of movement perpendicular to the crucible, the distance between the outer circumferential surface of the annular plate and the inner circumferential surface of the heater is greater than or equal to 15 mm and less than or equal to 29 mm; and / or, in the direction of movement perpendicular to the crucible, the minimum distance between the inner circumferential surface of the annular plate and the outer circumferential surface of the guide tube assembly is greater than or equal to 5 mm and less than or equal to 15 mm.

[0011] In one possible implementation of this application, a furnace body and a gas-gathering cylinder are also included, wherein the top of the furnace body has a second air inlet and the heat-insulating cylinder is located inside the furnace body; The gas-gathering cylinder is located inside the furnace body and is installed on top of the insulation cylinder. The gas-gathering cylinder is connected to the second air inlet and the first air inlet.

[0012] In one possible implementation of this application, a portion of the peripheral wall of the gas-gathering cylinder is recessed in a direction away from the central axis of the gas-gathering cylinder to define a clearance groove, the clearance groove extending axially along the gas-gathering cylinder to both ends of the gas-gathering cylinder. The single crystal furnace includes a cooling screen and a cooling screen water pipe. The cooling screen is located inside the guide tube assembly, and the cooling screen water pipe passes through the clearance groove and supplies water to the cooling screen.

[0013] In one possible implementation of this application, the inner diameter of the gas-gathering cylinder is larger than the outer diameter of the flow guide assembly.

[0014] In one possible implementation of this application, the single crystal furnace further includes a heat insulation element disposed inside the heat insulation cylinder, located below and spaced apart from the heater, and situated on the outer periphery of the crucible and spaced apart from the crucible.

[0015] In one possible implementation of this application, at least one flow guide groove is provided on the inner circumferential surface of the insulation member facing the crucible, the flow guide groove extends along the axial direction of the crucible and extends along the axial direction of the crucible to the upper end face of the insulation member to form an air inlet opening.

[0016] In one possible implementation of this application, the width of the air inlet of the guide channel is greater than the width of the lower end of the guide channel.

[0017] In one possible implementation of this application, the flow channel includes a flared channel and a guide channel; The flared groove is located above the guide groove and is connected to the guide groove, and the air intake opening is formed in the flared groove; The flared groove gradually decreases in width from top to bottom; and / or the guide groove gradually decreases in width from top to bottom. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a cross-sectional structural schematic diagram of a single crystal furnace according to some embodiments of the present invention.

[0021] Figure 2 This is a cross-sectional structural diagram of a single crystal furnace according to another perspective of the present invention.

[0022] Figure 3 In accordance with the present invention Figure 1 A magnified structural diagram of area A in the middle.

[0023] Figure 4 This is a schematic diagram of the sealing ring structure according to some embodiments of the present invention.

[0024] Figure 5 This is a schematic diagram of the structure of a gas-gathering cylinder according to some embodiments of the present invention.

[0025] Figure 6 This is a schematic diagram of the structure of a thermal insulation component according to some embodiments of the present invention.

[0026] As shown in the figure: 10. Insulation cylinder; 100. First air outlet; 101. Upper insulation cylinder; 102. Lower insulation cylinder; 103. Air guide cover; 104. Mounting port; 1010. Vent hole; 20. Wok base; 21. Support rod; 30. Draft tube assembly; 300. First air inlet; 301. Outer draft tube; 302. Inner draft tube; 40. Heater; 400. Annular flow channel; 50. Sealing ring; 500. Annular plate; 501. First sealing section; 502. Second sealing section; 503. Connecting cylinder; 5030. Exhaust passage; 60. Furnace body; 600. Second air inlet; 70. Air-gathering cylinder; 700. Clearance groove; 80. Cooling screen water pipes; 90. Thermal insulation component; 900. Flow guide groove; 901. Flared groove; 902. Guide groove. Detailed Implementation

[0027] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0028] In this application, the accompanying drawings are not necessarily drawn to scale, and local features may be enlarged or reduced to more clearly show the details of the local features.

[0029] Unless otherwise stated, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0030] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified. In the description of this application, "several" means one or more, unless otherwise explicitly specified.

[0031] In the description of this application, the terms “length”, “width”, “thickness”, “inner”, “outer”, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the purpose of simplifying the description of this application and do not indicate that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. In other words, they should not be construed as limitations on this application.

[0032] In the description of this application, unless otherwise expressly defined, the terms "installation," "connection," "linking," "fixing," "setting," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0033] In the description of this application, unless otherwise expressly defined, the terms "above," "over," "on top of," "below," "below," "under," or "below" for "first feature over second feature" can refer to the first and second features being in direct contact, or to the first and second features being in indirect contact through an intermediate medium. Furthermore, "above," "below," and "over" for "first feature over second feature" can mean the first feature is directly above or diagonally above the second feature, or simply indicates that the horizontal height of the first feature is higher than the horizontal height of the second feature. Similarly, "below," "below," and "below" for "first feature over second feature" can mean the first feature is directly below or diagonally below the second feature, or simply indicates that the horizontal height of the first feature is lower than the horizontal height of the second feature.

[0034] In related technologies, the industry generally adopts the following two methods to reduce the oxygen content in single crystal furnaces: One approach is to reduce the oxygen content of the product by adding an oxygen-reducing ring and shortening the length of the heater's heating zone, thereby decreasing the temperature at the bottom of the crucible and reducing the rate of oxygen evolution. However, the installation location of the oxygen-reducing ring and the oxygen-reducing technology in the heating zone are approaching the limits of existing technology, which significantly restricts the effectiveness of further reducing the oxygen content.

[0035] Secondly, the shape of the guide tube was adjusted. However, the structural points of the guide tube that affect the oxygen content are too close to the liquid surface of the crucible, which restricts the airflow distribution and reduces the oxygen removal efficiency.

[0036] Therefore, the above two methods have very limited effect on reducing the oxygen content of N-type single crystals and need further improvement.

[0037] To address the aforementioned technical problems, this application provides a single crystal furnace that can guide oxygen-containing gas, reduce the space for the oxygen-containing gas to escape, accelerate the discharge rate of the oxygen-containing gas, and thereby reduce the oxygen content in the single crystal furnace.

[0038] The single crystal furnace of the present invention will now be described with reference to the accompanying drawings.

[0039] like Figure 1 , Figure 2 and Figure 3As shown, the single crystal furnace of this embodiment of the invention may include a heat preservation cylinder 10, a crucible liner 20, a flow guide cylinder assembly 30, a heater 40, and a sealing ring 50.

[0040] The top of the insulation cylinder 10 has a mounting port 104. The mounting port 104 is used to provide a mounting position for the flow guide assembly 30.

[0041] For example, the mounting port 104 may be a stepped hole.

[0042] The bottom of the heat insulation cylinder 10 has a first air outlet 100, which is used to discharge the oxygen-containing gas inside the heat insulation cylinder 10.

[0043] For example, the insulation cylinder 10 includes an upper insulation cylinder 101 and a lower insulation cylinder 102, wherein the upper insulation cylinder 101 is connected to the upper end of the lower insulation cylinder 102. In other examples, the insulation cylinder 10 may also be a single piece.

[0044] The crucible 20 is internally connected to a crucible. The crucible holds the melt required for single-crystal silicon growth. The crucible 20 is movably disposed within the insulation cylinder 10 in a vertical direction. The top of the crucible 20 is open. This allows the crucible 20 to move along the insulation cylinder 10, changing its height position within the cylinder. Specifically, during the single-crystal silicon pulling process, as the melt in the crucible is continuously consumed, the liquid level continuously drops. To maintain a constant relative height between the melt level and the seed crystal, and to ensure uniform crystal rod diameter, the position of the crucible needs to be changed. In this application, the position of the crucible is changed by altering the height of the crucible 20 within the insulation cylinder 10, thereby ensuring the relative height between the melt level and the seed crystal in the crucible.

[0045] In some embodiments, the single crystal furnace includes a support rod 21 and a drive mechanism. The support rod 21 is movable vertically relative to the insulation cylinder 10. One end of the support rod 21 extends into the insulation cylinder 10 and connects to the bottom of the crucible liner 20, while the other end extends to the outside of the insulation cylinder 10 and connects to an external drive mechanism (not shown in the figure). The drive mechanism is configured to drive the support rod 21 to move vertically, thereby using the drive mechanism to drive the support rod 21 to push the crucible liner 20 vertically. For example, the drive mechanism may be a hydraulic or pneumatic lifting mechanism.

[0046] The flow guide tube assembly 30 is located at the mounting port 104. Exemplarily, the assembly relationship between the flow guide tube assembly 30 and the insulation cylinder 10 includes, but is not limited to, snap-fit ​​or overlapping. For example, the mounting port 104 may be a stepped hole, and the portion of the flow guide tube assembly 30 that contacts the mounting port 104 is adapted to the stepped hole.

[0047] In some embodiments, the guide tube assembly 30 includes an outer guide tube 301 and an inner guide tube 302. The upper end of the outer guide tube 301 is located at the mounting port 104, forming an upper fixed end. The inner guide tube 302 is coaxially arranged within the internal cavity of the outer guide tube 301. The upper end of the inner guide tube 302 is press-fitted to the upper end of the outer guide tube 301, ensuring axial connection between the two. Since the detailed structure and working principle of the guide tube assembly 30 are mature technologies in the industry, their specific construction will not be elaborated upon here.

[0048] The guide tube assembly 30 is located on the upper side of the crucible 20. The top of the guide tube assembly 30 has a first air inlet 300, and the lower end of the guide tube assembly 30 is located on the inner circumference of the crucible 20 and communicates with the crucible 20.

[0049] This design utilizes the flow guide assembly 30 to construct a directional flow channel for the protective gas. During the production of single crystals in the single crystal furnace, the protective gas can enter the flow guide assembly 30 through the first gas inlet 300, and be transported downwards to the inner cavity of the crucible liner 20, and then into the crucible. The protective gas forms a stable gas protective layer inside the crucible, continuously and rapidly carrying away the oxygen and other byproducts generated in the reaction from the reaction interface, effectively maintaining the stability of the reaction environment inside the crucible.

[0050] For example, protective gases include, but are not limited to, inert gases such as argon or helium.

[0051] The heater 40 is located inside the insulation cylinder 10 and is arranged around the crucible 20.

[0052] For example, the single crystal furnace includes a corner plate bracket (not shown in the figure), through which the heater 40 can be connected to the insulation cylinder 10.

[0053] The heater 40 can be a closed ring extending circumferentially along the crucible 20, forming a ring around the crucible 20, which can uniformly heat the crucible.

[0054] For example, heater 40 can generate high temperature through resistance heating (graphite heater) or electromagnetic induction heating (induction heater) and heat crucible 20 by thermal radiation to transfer heat to the crucible so that the polycrystalline silicon raw material in the crucible is heated above the melting point of silicon, thereby creating a temperature field in the crucible that meets the process requirements.

[0055] The heater 40 and the crucible 20 are spaced apart to define an annular flow channel 400, which is connected to the first air outlet 100.

[0056] Please see Figure 3 and Figure 4The sealing ring 50 is installed on the upper end of the crucible liner 20. For example, the sealing ring 50 can be installed on the upper end of the crucible liner 20 by direct overlap, or by other detachable connection methods. There are no restrictions here, and the specific choice can be made according to the actual situation.

[0057] The sealing ring 50 includes an annular plate 500.

[0058] The annular plate 500 includes a first sealing portion 501 located on the inner periphery of the crucible 20 and a second sealing portion 502 located on the outer periphery of the crucible 20. It can be understood that the inner periphery of the crucible 20 refers to the radially inner region of the crucible 20 facing the guide tube assembly 30, while the outer periphery of the crucible 20 refers to the radially outer region of the crucible 20 away from the guide tube assembly 30. The first sealing portion 501, located on the inner periphery of the crucible 20, is positioned at the gap between the crucible 20 and the guide tube assembly 30, restricting gas flow and reducing oxygen escape. The second sealing portion 502, located on the outer periphery of the crucible 20, reduces the gap between the crucible 20 and the heater 40, restricting oxygen flow and reducing the area where oxygen escapes.

[0059] In some embodiments, an exhaust channel 5030 is defined between the sealing ring 50 and the upper end of the crucible 20, and the exhaust channel 5030 connects the annular flow channel 400 and the interior of the crucible 20. It should be noted that the sealing ring 50 and the upper end of the crucible 20 cooperate to define the exhaust channel 5030. Specifically, there are three possibilities: First, the exhaust channel 5030 can be designed as a through-groove formed at the upper end of the crucible 20. This through-groove penetrates the crucible 20 along the distribution direction of its inner and outer circumferential surfaces, and the upper opening of the through-groove is closed by the sealing ring 50, thereby forming an exhaust channel 5030 for gas flow. Second, the exhaust channel 5030 can also be a through-groove formed on the sealing ring 50, which also penetrates the sealing ring 50 along the distribution direction of its inner and outer circumferential surfaces, and the lower opening of the through-groove is closed by the crucible 20, thus constituting the exhaust channel 5030. Third, the exhaust passage 5030 can also be composed of through grooves respectively formed on the sealing ring 50 and the crucible 20. These two through grooves are interconnected, thus forming the gas exhaust passage 5030.

[0060] It should be noted that the sealing ring 50 and the upper end of the crucible 20 cooperate to define the exhaust channel 5030. In order to ensure the smooth exhaust of the exhaust channel 5030, the height of the crucible needs to be lower than the height of the exhaust channel 5030, so as to avoid the crucible blocking the exhaust channel 5030 and causing the exhaust to be obstructed.

[0061] In other embodiments, the sealing ring 50 has an exhaust channel 5030 extending through the sealing ring 50 along the distribution direction of its inner and outer circumferential surfaces. The exhaust channel 5030 connects the annular flow channel 400 and the interior of the crucible 20. It should be noted that, compared to the exhaust channel 5030 in the above embodiments, the exhaust channel 5030 in this embodiment has an optimized structural design, with no opening at its bottom end. This eliminates the need to rely on the crucible 20 to seal the bottom opening and limit the exhaust channel 5030, simplifying the overall structure and design requirements.

[0062] Specifically, during the operation of the single crystal furnace, the high-temperature environment inside the insulation cylinder 10 triggers a chemical reaction of oxygen-containing compounds, continuously generating oxygen. When a protective gas (such as argon) is continuously introduced into the insulation cylinder 10, the gas carries the oxygen and other volatiles generated in the crucible 20 and escapes outward from the gap between the crucible 20 and the guide cylinder assembly 30. However, due to the restriction of the first sealing section 501, most of the gas is guided into the exhaust channel 5030 by the first sealing section 501, thereby reducing the probability of direct diffusion to other areas (the cavity between the insulation cylinder 10 and the guide cylinder assembly 30), and thus reducing the amount of oxygen retained in the cavity between the insulation cylinder 10 and the guide cylinder assembly 30.

[0063] After the gas flows into the annular flow channel 400 through the exhaust channel 5030, the second sealing section 502 further constrains the airflow path, further reducing the possibility of gas escape, causing the gas to flow downwards along the annular flow channel 400. Finally, the gas is efficiently discharged through the first outlet 100, forming a continuous gas guiding path of "exhaust channel 5030 - annular flow channel 400 - first outlet 100". By restricting the directional flow of gas, reducing the gas escape area, and shortening the residence time and amount of gas in the insulation cylinder 10, the purpose of rapid discharge is achieved, thereby effectively reducing the oxygen content in the single crystal furnace.

[0064] Please continue reading. Figure 4 In some embodiments, the sealing ring 50 further includes a connecting cylinder 503. The connecting cylinder 503 is connected to the end face of the annular plate 500 facing the crucible 20 and is connected to the upper end face of the crucible 20. The connection between the connecting cylinder 503 and the crucible 20 includes, but is not limited to, overlapping, snap-fit, and other connection methods.

[0065] The first sealing part 501 and the second sealing part 502 are located on both sides of the connecting cylinder 503. The first sealing part 501 and the second sealing part 502 can be integrally molded with the connecting cylinder 503 to improve the structural strength of the sealing ring 50.

[0066] For example, when an exhaust passage 5030 is defined between the sealing ring 50 and the upper end of the crucible 20, the exhaust passage 5030 may be defined between the connecting cylinder 503 and the upper end face of the crucible 20. For example, when the sealing ring 50 is formed with an exhaust passage 5030 that extends through the sealing ring 50 along the distribution direction of the inner and outer circumferential surfaces of the sealing ring 50, the exhaust passage 5030 may be formed in the connecting cylinder 503. In this way, it is not necessary to use the crucible 20 to close the axial opening of the exhaust passage 5030, and its structure is simpler.

[0067] In some embodiments of the present invention, such as Figure 3 As shown, the crucible 20 has a lower limit position, which refers to the lowest position that the crucible 20 can reach by moving in the vertical direction. At the lower limit position, the annular plate 500 is located between the upper end of the heater 40 and the lower end of the guide tube assembly 30 in the vertical direction. In the direction perpendicular to the movement of the crucible 20, the distance W1 between the outer circumferential surface of the annular plate 500 and the inner circumferential surface of the heater 40 is greater than or equal to 15 mm and less than or equal to 29 mm, i.e., W1 satisfies 15 mm ≤ W1 ≤ 29 mm. This distance ensures, on the one hand, a safe distance between the annular plate 500 and the heater 40, avoiding the risk of discharge and sparking caused by thermal radiation or electromagnetic induction between the heater 40 and the annular plate 500 under high-temperature conditions; on the other hand, this distance also prevents the annular plate 500 from being squeezed when the insulation cylinder 10 undergoes slight deformation, thereby extending the service life of the annular plate 500 and maintaining structural stability, facilitating the smooth movement of the crucible 20.

[0068] Based on this, in some embodiments, when the insulation cylinder 10 includes an upper insulation cylinder 101 and a lower insulation cylinder 102, the heater 40 and the upper insulation cylinder 101 are arranged coaxially, and their inner diameters are the same. This means that there is also a radial distance W1 between the outer circumferential surface of the annular plate 500 and the inner circumferential surface of the upper insulation cylinder 101. When the annular plate 500 moves upward with the crucible 20 and enters the cavity of the upper insulation cylinder 101, a certain gap will still remain between it and the upper insulation cylinder 101, thus effectively preventing them from colliding.

[0069] In some embodiments of the present invention, such as Figure 3As shown, the crucible 20 has a lower limit position, which refers to the lowest position that the crucible 20 can reach in the vertical movement direction. In the lower limit position, the annular plate 500 is located between the upper end of the heater 40 and the lower end of the guide tube assembly 30 in the vertical direction. In the direction perpendicular to the movement of the crucible 20, the minimum distance W2 between the inner circumferential surface of the annular plate 500 and the outer circumferential surface of the guide tube assembly 30 is greater than or equal to 5 mm and less than or equal to 15 mm, that is, W2 satisfies 5 mm ≤ W2 ≤ 15 mm. This minimum distance setting can ensure that there is a gap between the annular plate 500 and the guide tube assembly 30, so that the annular plate 500 will not scrape against the crucible 20 during its movement, and can also reduce the overflow of gas through the gap between the annular plate 500 and the guide tube assembly 30.

[0070] It should be noted that, since a sealing ring 50 has been added to the crucible liner 20, in order to ensure the distance between the bottom of the guide tube assembly 30 and the liquid surface of the crucible, the length of the insulation tube 10 and the length of the outer guide tube 301 need to be adjusted accordingly to increase the height of the upper edge of the crucible liner 20.

[0071] Optionally, the bottom end of the outer guide tube 301 has an inclined surface, which surrounds the inner guide tube 302. The inclined surface slopes downward toward the inner guide tube 302, and the angle of inclination is 13°-18°, preferably 15°. This allows for thermal field and melt convection below the guide tube assembly 30, thereby optimizing the utilization efficiency of silicon material in the crucible. This ensures that the bottom material in the crucible crystallizes into a single crystal and avoids excessive residue at the bottom of the crucible.

[0072] In other embodiments of the present invention, the crucible 20 has a lower limit position, which refers to the lowest safe position that the crucible 20 can reach in the vertical movement direction. In the lower limit position, in the vertical direction, the annular plate 500 is located between the upper end of the heater 40 and the lower end of the guide tube assembly 30. In the movement direction perpendicular to the crucible 20, the distance between the outer circumferential surface of the annular plate 500 and the inner circumferential surface of the heater 40 is greater than or equal to 15 mm and less than or equal to 29 mm. Furthermore, in the movement direction perpendicular to the crucible 20, the minimum distance between the inner circumferential surface of the annular plate 500 and the outer circumferential surface of the guide tube assembly 30 is greater than or equal to 5 mm and less than or equal to 15 mm. In other words, this design ensures a safe distance between the annular plate 500 and the heater 40, avoiding the risk of discharge and sparking caused by thermal radiation or electromagnetic induction between the heater 40 and the annular plate 500 under high-temperature conditions. It also prevents the insulation cylinder 10 from compressing the annular plate 500 when it deforms, thereby extending the service life of the annular plate 500 and maintaining structural stability. At the same time, the addition of a minimum spacing ensures that there is a gap between the annular plate 500 and the guide tube assembly 30, so that the annular plate 500 will not scrape against the guide tube assembly 30 as it moves with the crucible 20, and also reduces the overflow of gas through the gap between the annular plate 500 and the guide tube assembly 30.

[0073] In some embodiments, such as Figure 1 As shown, the single crystal furnace also includes a furnace body 60 and a gas concentrator 70. The top of the furnace body 60 has a second air inlet 600. The insulation cylinder 10 is located inside the furnace body 60. The gas concentrator 70 is located inside the furnace body 60 and is installed on top of the insulation cylinder 10. The gas concentrator 70 is connected to the second air inlet 600 and the first air inlet 300. The gas concentrator 70 is located inside the furnace body 60 and is installed on top of the insulation cylinder 10.

[0074] For example, the material of the air-gathering cylinder 70 can be solid felt or carbon fiber, which can be selected according to the actual situation.

[0075] This means that the gas-concentrating cylinder 70 is installed in the cavity formed by the insulation cylinder 10 and the top of the furnace body 60. Its function is to achieve efficient oxygen reduction through the dual effects of space occupation and airflow guidance. Specifically, the gas-concentrating cylinder 70 compresses the volume of gas escaping from the cavity by physically occupying space. Combined with its connection design with the second air inlet 600 and the first air inlet 300, it constructs a guiding air path, guiding the protective gas to the guide cylinder assembly 30 at high speed along a preset path, significantly reducing the ineffective diffusion in traditional designs without a gas-concentrating cylinder.

[0076] Compared to the condition without a gas-gathering cylinder, the protective gas, after entering through the second inlet 600, tends to freely dissipate within the top cavity, forming a large-area vortex zone. This results in a sharp decrease in gas velocity, and in some areas, gaseous impurities may even become trapped and circulate. At this point, oxygen-containing impurities, such as silica (SiO) volatiles, easily condense in the vortex zone and fall back into the melt, decomposing to generate a secondary oxygen source. Simultaneously, the low-speed airflow prolongs the contact time between impurities and the silicon melt and graphite hot zone components, intensifying the oxidation reaction and making it difficult to control the oxygen concentration within the furnace body 60.

[0077] By designing the gas-concentrating cylinder 70, which occupies the core area of ​​the cavity, the originally dispersed airflow is constrained into a directional high-speed jet, significantly increasing the argon gas flux through the melt surface per unit time. The high-speed airflow not only accelerates the removal efficiency of oxygen-containing impurities (such as SiO), but also reduces the diffusion residence time of impurities in the furnace body 60, inhibiting their secondary reactions with the silicon melt and graphite components, thus achieving the purpose of oxygen reduction.

[0078] Optionally, the gas-gathering cylinder 70 is located inside the furnace body 60, and the end of the gas-gathering cylinder 70 away from the insulation cylinder 10 can directly abut against the inner top wall of the furnace body 60 or be spaced apart.

[0079] The advantage of having the gas-gathering cylinder 70 in contact with the furnace body 60 is that when the end of the gas-gathering cylinder 70 furthest from the insulation cylinder 10 is sealed against the inner top wall of the furnace body 60, this design forms a completely closed gas flow channel through the tight contact between surfaces. This completely blocks the escape path of the protective gas to the cavity between the outer periphery of the gas-gathering cylinder 70 and the top wall of the furnace body 60, effectively suppressing eddy formation and improving gas flow efficiency and oxygen impurity discharge rate.

[0080] The design of separating the end of the gas-gathering cylinder 70 away from the insulation cylinder 10 from the inner top wall of the furnace body 60 by 5-10mm allows for a small amount of gas bypass, causing a small amount of gas to escape along the gap. However, this design significantly improves assembly adaptability. The tolerance design avoids assembly stress caused by manufacturing tolerances and thermal expansion differences between the insulation cylinder 10 and the furnace body 60, and prevents the gas-gathering cylinder 70 from being deformed due to forced compression, which would affect the structural lifespan.

[0081] Furthermore, such as Figure 1 As shown, the inner diameter of the gas-gathering cylinder 70 is larger than the outer diameter of the guide cylinder assembly 30. During assembly or when adding raw materials, the guide cylinder assembly 30 can move relative to the gas-gathering cylinder 70. Since the inner diameter of the gas-gathering cylinder 70 is larger than the outer diameter of the guide cylinder assembly 30, the movement of the guide cylinder assembly 30 is not affected by the gas-gathering cylinder 70. This allows the gas-gathering effect to be achieved without affecting the operation of the guide cylinder assembly 30. The height, inner diameter, and other dimensions of the gas-gathering cylinder 70 can be adjusted according to the furnace type and the size of the hot zone.

[0082] In some embodiments, the single crystal furnace includes a cooling screen water pipe 80 and a lifting device (not shown in the figure), forming a vertical drive unit of the guide tube assembly 30. The lifting device is arranged outside the furnace body 60, and the drive end of the lifting device is connected to one end of the cooling screen water pipe 80. A through hole is pre-set at the upper end of the furnace body 60, and the other end of the cooling screen water pipe 80 passes through the through hole into the furnace body 60 and is connected to the outer guide tube 301 through a chain (not shown in the figure). When the lifting device performs a lifting action, the axial displacement of the cooling screen water pipe 80 is transmitted, and the outer guide tube 301 is moved upward synchronously through the chain, thereby driving the entire guide tube assembly 30 to achieve vertical adjustment. The lifting device can be a hydraulic rod. The integrated design of the cooling screen water pipe 80 and the lifting device, as well as the transmission connection relationship between the two and the guide tube assembly 30, are all prior art and will not be described in detail.

[0083] Please continue reading. Figure 5 In some embodiments, a portion of the peripheral wall of the gas-gathering cylinder 70 is recessed away from the central axis of the gas-gathering cylinder 70 to define a clearance groove 700, which extends axially along the gas-gathering cylinder 70 to both ends of the gas-gathering cylinder 70. Exemplarily, the clearance groove 700 may be a rectangular groove, a U-shaped groove, etc. The single crystal furnace includes a cooling screen (not shown in the figure) and a cooling screen water pipe 80. The cooling screen is disposed inside the guide tube assembly 30, and the cooling screen water pipe 80 passes through the clearance groove 700 and supplies water to the cooling screen, allowing cooling water to circulate inside the cooling screen, thereby cooling the crystal rods that pass through the cooling screen axially. The connection relationship and structure between the cooling screen and the cooling screen water pipe 80 are prior art and will not be described in detail here.

[0084] In this embodiment of the application, by providing a clearance groove 700 on the air-gathering cylinder 70, sufficient clearance space is reserved for the cooling screen water pipe 80, and the cooling screen water pipe 80 can move freely along the clearance groove 700 without being restricted by the structure of the air-gathering cylinder 70.

[0085] like Figure 2 and Figure 6 As shown, in some embodiments, the single crystal furnace may further include a heat insulation component 90, which is disposed inside the heat insulation cylinder 10. The heat insulation component 90 is located below the heater 40 and spaced apart from the heater 40. The heat insulation component 90 is located on the outer periphery of the crucible 20 and spaced apart from the crucible 20. The spaced heat insulation component 90 from the crucible 20 can prevent the crucible 20 from moving up and down during operation, thus avoiding the risk of powder falling due to mutual friction and sparking.

[0086] In this embodiment, the heat insulation element 90 replaces the oxygen reduction ring in the prior art. Since oxygen atoms play a decisive role in the quality of the single crystal rod during the single crystal pulling process, and the main source of oxygen is the oxygen precipitated from the quartz crucible at high temperatures, which then diffuses into the molten silicon. Furthermore, the rate of oxygen precipitation increases with temperature. By arranging the heat insulation element 90 below the heater 40, maintaining a certain distance from it, and placing it on the outer periphery of the crucible liner 20, the heat insulation element 90 effectively blocks the heat radiation generated by the heater 40, reducing the amount of heat radiated to the bottom of the crucible. This lowers the crucible temperature, reducing the rate of oxygen precipitation and thus achieving the purpose of oxygen reduction.

[0087] On the other hand, the insulation component 90 fills the cavity between the insulation cylinder 10 and the crucible liner 20, which can compress the lower space of the thermal field, reduce the gas escape area and the gas vortex. In this way, the gas can flow quickly through the gap between the insulation component 90 and the crucible liner 20, significantly increasing the gas flow velocity.

[0088] For example, the insulation component 90 may be made of a solid felt material and extend around the crucible 20 to increase the coverage area and improve the filling effect of the space.

[0089] In addition, the insulation component 90 compresses the lower thermal field space, reducing the heat transfer time and distance in the thermal field and reducing heat loss within the furnace body 60, thereby achieving the effect of reducing power consumption.

[0090] For example, two insulation elements 90 may be provided, with a certain gap between them. The gap area can provide clearance for the corner plate bracket connected to the heater 40, thereby facilitating the installation of the corner plate bracket (not shown in the figure) inside the insulation cylinder 10.

[0091] like Figure 6 As shown, in some embodiments, at least one flow guide groove 900 is provided on the inner circumferential surface of the insulation member 90 facing the crucible 20. The flow guide groove 900 extends along the axial direction of the crucible 20 and extends to the upper end face of the insulation member 90 to form an air inlet. There may be multiple flow guide grooves 900, such as 2, 3, 4, etc., and the multiple flow guide grooves 900 are arranged at equal intervals to facilitate the flow of more gas.

[0092] In the embodiments of this application, by setting the flow guide trough 900, the flow direction of the gas can be guided, reducing gas turbulence and accelerating gas flow, thereby achieving the purpose of reducing oxygen.

[0093] Furthermore, such as Figure 6As shown, the width of the air inlet opening of the guide channel 900 is greater than the width of the lower end of the guide channel 900. On the one hand, the wider air inlet opening allows more gas to flow in. On the other hand, the width of the lower end of the guide channel 900 becomes narrower, the smaller the cross-sectional area, and the greater the gas flow velocity. Therefore, it can accelerate the gas, thereby improving the gas discharge efficiency and achieving the purpose of reducing oxygen.

[0094] In some embodiments, such as Figure 6 As shown, the guide channel 900 includes a flared channel 901 and a guide channel 902. The flared channel 901 is located above the guide channel 902 and is connected to the guide channel 902. The air inlet is formed in the flared channel 901. The width of the flared channel 901 gradually decreases from top to bottom. In this way, by utilizing the gradually decreasing width of the flared channel 901 from top to bottom, on the one hand, the larger opening at the upper end of the flared channel 901 allows more gas to enter, and on the other hand, as the gas flows in, the width of the flared channel 901 gradually decreases, which can accelerate the gas, thereby improving the gas discharge efficiency and achieving the purpose of reducing oxygen.

[0095] In other embodiments, the guide channel 900 includes a flared channel 901 and a guide channel 902. The flared channel 901 is located above the guide channel 902 and is connected to the guide channel 902. An air inlet is formed in the flared channel 901. The guide channel 902 gradually narrows in width from top to bottom. As a result, gas flows into the guide channel 902 through the flared channel 901. As the guide channel 902 gradually narrows in width from top to bottom, it can accelerate the gas, thereby improving the gas discharge efficiency and achieving the purpose of reducing oxygen.

[0096] In other embodiments, the guide channel 900 includes a flared channel 901 and a guide channel 902. The flared channel 901 is located above and connected to the guide channel 902. An air inlet is formed in the flared channel 901. The width of the flared channel 901 gradually decreases from top to bottom, and the width of the guide channel 902 also gradually decreases from top to bottom. As a result, the gas is accelerated for the first time when flowing through the flared channel 901 and accelerated a second time when flowing through the guide channel 902, forming a double acceleration effect, which further improves the gas discharge efficiency and achieves the purpose of reducing oxygen.

[0097] Optionally, the lower end of the flared groove 901 has the same width as the upper end of the guide groove 902, which can reduce the resistance during gas flow and improve the smoothness of gas flow.

[0098] In some embodiments, such as Figure 2As shown, the insulation cylinder 10 has a first air outlet 100 at its bottom. The single crystal furnace also includes a gas guide hood 103, which is located inside the insulation cylinder and covers the first air outlet 100. The gas guide hood 103 has a vent hole 1010. The lower end of the guide channel 900 is at the same horizontal level as the vent hole 1010. It can be understood that when the lower end of the guide channel 900, i.e., its air outlet, is at the same horizontal level as the vent hole 1010, the gas discharged from the guide channel 900 can directly and smoothly enter the gas guide hood 103 through the vent hole 1010 and be quickly discharged. This design effectively shortens the gas discharge path and greatly reduces the gas escape phenomenon during the discharge process.

[0099] Optionally, the single crystal furnace may also include a gas extraction device (not shown in the figure), which is configured to extract gas. The gas extraction device has an extraction end that can be inserted into the gas guide hood 103. By extracting gas, the flow rate of the gas is increased, the residence time of oxygen is reduced, and the purpose of deoxygenation is achieved.

[0100] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0101] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A single crystal furnace, characterized in that, include: The heat insulation cylinder (10) has an installation port (104) at the top and a first air outlet (100) at the bottom. The crucible (20) is movably disposed inside the heat preservation cylinder (10) in the vertical direction, and the top of the crucible (20) is open. A flow guide tube assembly (30) is provided at the mounting port (104). The flow guide tube assembly (30) is located on the upper side of the crucible (20). The top of the flow guide tube assembly (30) has a first air inlet (300). The lower end of the flow guide tube assembly (30) is located on the inner circumference of the crucible (20) and communicates with the crucible (20). A heater (40) is disposed inside the insulation cylinder (10) and surrounding the crucible (20). The heater (40) is spaced apart from the crucible (20) to define an annular flow channel (400), which is connected to the first air outlet (100). A sealing ring (50) is installed at the upper end of the crucible (20). The sealing ring (50) includes an annular plate (500), which includes a first sealing portion (501) located on the inner periphery of the crucible (20) and a second sealing portion (502) located on the outer periphery of the crucible (20). An exhaust passage (5030) is defined between the sealing ring (50) and the upper end of the crucible (20). Alternatively, the sealing ring (50) is formed with an exhaust passage (5030) that extends through the sealing ring (50) along the distribution direction of the inner and outer peripheral surfaces of the sealing ring (50). The exhaust passage (5030) connects the annular flow channel (400) and the interior of the crucible (20).

2. The single crystal furnace according to claim 1, characterized in that, The sealing ring (50) includes: a connecting cylinder (503), which is connected to the end face of the annular plate (500) facing the crucible (20) and connected to the upper end face of the crucible (20); the first sealing part (501) and the second sealing part (502) are located on both sides of the connecting cylinder (503); Wherein, an exhaust channel (5030) is defined between the connecting cylinder (503) and the upper end face of the crucible (20), or the connecting cylinder (503) is formed with the exhaust channel (5030).

3. The single crystal furnace according to claim 1, characterized in that, The crucible (20) has a lower limit position, in which the annular plate (500) is located between the upper end of the heater (40) and the lower end of the guide tube assembly (30) in the vertical direction; In the direction of movement perpendicular to the crucible (20), the distance between the outer peripheral surface of the annular plate (500) and the inner peripheral surface of the heater (40) is greater than or equal to 15 mm and less than or equal to 29 mm; and / or, in the direction of movement perpendicular to the crucible (20), the minimum distance between the inner peripheral surface of the annular plate (500) and the outer peripheral surface of the guide tube assembly (30) is greater than or equal to 5 mm and less than or equal to 15 mm.

4. The single crystal furnace according to claim 1, characterized in that, It also includes a furnace body (60) and an air-gathering cylinder (70), the top of which has a second air inlet (600), and the heat-insulating cylinder (10) is located inside the furnace body (60); The gas-gathering cylinder (70) is located inside the furnace body (60) and installed on top of the insulation cylinder (10). The gas-gathering cylinder (70) is connected to the second air inlet (600) and the first air inlet (300).

5. The single crystal furnace according to claim 4, characterized in that, A portion of the peripheral wall of the gas-gathering cylinder (70) is recessed in a direction away from the central axis of the gas-gathering cylinder (70) to define a clearance groove (700), the clearance groove (700) extending axially along the gas-gathering cylinder (70) to both ends of the gas-gathering cylinder (70). The single crystal furnace includes a cooling screen and a cooling screen water pipe (80). The cooling screen is located inside the guide tube assembly (30), and the cooling screen water pipe (80) passes through the clearance groove (700) and supplies water to the cooling screen.

6. The single crystal furnace according to claim 4 or 5, characterized in that, The inner diameter of the gas-gathering cylinder (70) is larger than the outer diameter of the flow guide assembly (30).

7. The single crystal furnace according to claim 1, characterized in that, It also includes a heat insulation component (90), which is disposed inside the heat insulation cylinder (10). The heat insulation component (90) is located below the heater (40) and spaced apart from the heater (40). The heat insulation component (90) is located on the outer periphery of the crucible (20) and spaced apart from the crucible (20).

8. The single crystal furnace according to claim 7, characterized in that, At least one flow guide groove (900) is provided on the inner circumferential surface of the insulation component (90) facing the crucible (20). The flow guide groove (900) extends along the axial direction of the crucible (20) and extends along the axial direction of the crucible (20) to the upper end face of the insulation component (90) to form an air inlet opening.

9. The single crystal furnace according to claim 8, characterized in that, The width of the air inlet of the guide channel (900) is greater than the width of the lower end of the guide channel (900).

10. The single crystal furnace according to claim 9, characterized in that, The flow channel (900) includes a flared channel (901) and a guide channel (902); The flared groove (901) is located above the guide groove (902) and is connected to the guide groove (902), and the air intake opening is formed in the flared groove (901). The flared groove (901) gradually decreases in width from top to bottom; and / or the guide groove (902) gradually decreases in width from top to bottom.

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