Crystal pulling system and control method thereof

Abstract

The invention discloses a crystal pulling system and a control method thereof. The crystal pulling system comprises a crucible assembly which comprises an outer crucible and an inner crucible, the outer crucible surrounds the outer portion of the inner crucible, and a crystal growing area is formed in the inner crucible; the feeding pipe is located above the crucible assembly, and the lower end of the feeding pipe extends to the position between the outer crucible and the inner crucible; the air curtain device is located between the feeding pipe and the inner crucible in the radial direction, and the air curtain device is used for supplying air to the position between the feeding pipe and the inner crucible so as to form shielding airflow surrounding the inner crucible. Therefore, the probability that the dust is in contact with the growing single crystal silicon rod is reduced, defects and dislocation caused by the dust are avoided, and the quality of the produced single crystal silicon is greatly improved compared with the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of single crystal silicon production, and in particular to a crystal pulling system and a control method thereof. Background Art

[0002] With the widespread application of single crystal silicon, the preparation process of single crystal silicon has gradually developed, from multiple crystal pulling technology (Recharged Czocharlski, referred to as RCZ) to continuous Czocharlski single crystal technology (Continuous Czocharlski, referred to as CCZ).

[0003] At present, when growing single crystal silicon by CCZ method, solid raw materials are first continuously added to the quartz crucible of the crystal pulling system for melting to form silicon melt, and then the seed crystal is lowered into the melt and slowly rises from the melt, so that the melt solidifies on the seed crystal and grows a single crystal silicon rod. During this period, the following technical difficulties are faced: the added solid raw materials may be suspended in the air due to dust, mutual collision and other reasons. These solid raw materials suspended in the air can be generally defined as "dust"; during the growth of single crystal silicon, these dusts are very likely to move toward the growing crystal rod, thereby contacting the growing crystal rod, and then causing defects and dislocations in the grown single crystal silicon.

[0004] Therefore, in the preparation of single crystal silicon, how to prevent dust from contacting the growing crystal rod is of great significance to improving the quality of single crystal silicon. Summary of the invention

[0005] The object of the present invention is to provide a crystal pulling system and a control method thereof, so as to solve the problem of defects and dislocations in single crystal silicon caused by dust.

[0006] To achieve the above-mentioned purpose, an embodiment of the present invention provides a crystal pulling system. The crystal pulling system comprises:

[0007] A crucible assembly, comprising an outer crucible and an inner crucible, wherein the outer crucible surrounds the outside of the inner crucible, and the interior of the inner crucible forms a crystal growth zone;

[0008] A feeding pipe, which is located above the crucible assembly and has a lower end extending between the outer crucible and the inner crucible;

[0009] An air curtain device is located between the feeding tube and the inner crucible in the radial direction, and is used for supplying air between the feeding tube and the inner crucible to form a shielding airflow surrounding the inner crucible.

[0010] As a further improvement of an embodiment, the air curtain device includes a plurality of air inlet pipes, and the plurality of air inlet pipes circumferentially surround the radial outer side of the inner crucible;

[0011] Alternatively, the air curtain device comprises:

[0012] An inner cylinder surrounding the radially outer side of the inner crucible;

[0013] an outer cylinder, which is sleeved on the outer side of the inner cylinder and spaced apart from the inner cylinder; and

[0014] An air intake passage is defined by the inner wall of the outer cylinder and the outer wall of the inner cylinder.

[0015] As a further improvement of an embodiment, the inner wall of the outer crucible and the outer wall of the inner crucible jointly define a melting zone, and the melting zone and the crystal growth zone are connected through an opening at the lower part of the inner crucible; the feeding pipe extends downward toward the melting zone, and the shielding airflow is formed directly above the melting zone;

[0016] Alternatively, the crucible assembly also includes a middle crucible, which is surrounded by the inner crucible and the outer crucible, the inner wall of the outer crucible and the outer wall of the middle crucible jointly define a melting zone, the inner wall of the middle crucible and the outer wall of the inner crucible jointly define a transition zone, the melting zone and the crystal growth zone are connected via the transition zone; the feeding pipe extends downward toward the melting zone, and the wind curtain device is radially located between the outer crucible and the middle crucible, so that the shielding airflow is formed directly above the transition zone.

[0017] As a further improvement of one embodiment, the lower end of the air curtain device is lower than at least one of the upper edge of the inner crucible and the upper edge of the middle crucible.

[0018] As a further improvement of one embodiment, the crystal pulling system further includes:

[0019] A first air supply device, which is connected to the feeding pipe to supply a feed air flow to the feeding pipe;

[0020] a second gas supply device, used for supplying a cooling gas flow to the top of the crucible assembly;

[0021] a guide tube, which is axially located between the exhaust port of the second gas supply device and the crucible assembly and guides the cooling gas flow to the middle of the inner crucible;

[0022] a third air supply device, which is connected to the air curtain device to supply a shielding airflow to the air curtain device;

[0023] A control device is electrically connected to and controls the first air supply device, the second air supply device and the third air supply device.

[0024] As a further improvement of one embodiment, the control device controls the feeding air flow rate v1 of the first gas supply device, the cooling air flow rate v2 of the second gas supply device, and the shielding air flow rate v3 of the third gas supply device, so that an airflow from the inside to the outside is formed at the upper edge of the inner crucible or the upper edge of the middle crucible.

[0025] As a further improvement of one embodiment, the feed air flow rate v1 of the first air supply device, the cooling air flow rate v2 of the second air supply device, and the shielding air flow rate v3 of the third air supply device meet 0.4v2 2 -0.8v2+0.2v3 2 -0.3v3-0.5v1 2 +v1-1≥k;

[0026] Where k ≥ 0 and is a constant, and the unit of v1, v2 and v3 is m / s.

[0027] As a further improvement of one embodiment, the crystal pulling system further includes:

[0028] A furnace body, wherein a furnace cavity is formed inside the furnace body, and the crucible assembly, the feeding pipe, the air curtain device and the guide tube are arranged in the furnace cavity;

[0029] an exhaust pipeline having an air inlet and an air outlet, wherein the air inlet is located above the melting zone and radially between the feeding pipe and the outer crucible, and the air outlet is connected to the outside of the furnace body;

[0030] An exhaust device is connected to the exhaust pipeline and is used to form an exhaust air flow from the air inlet to the air outlet.

[0031] To achieve the above-mentioned purpose, an embodiment of the present invention provides a control method of the crystal pulling system. The control method comprises:

[0032] Controlling the first air supply device to supply a feed air flow with a flow rate v1 to the feed pipe;

[0033] Control the second gas supply device to supply a cooling gas flow with a flow rate v2, and make the cooling gas flow flow from top to bottom toward the crystal growth area;

[0034] Control the third air supply device to supply air to the air curtain device at an air flow rate v3;

[0035] Among them, 0.4v2 2 -0.8v2+0.2v3 2 -0.3v3-0.5v1 2 +v1-1≥k, k≥0 and is a constant, the unit of v1, v2 and v3 is m / s.

[0036] As a further improvement of one implementation mode, 0.4v2 2 -0.8v2+0.2v3 2 -0.3v3-0.5v1 2 +v1-1≤k1, k1≤5 and is a constant.

[0037] Compared with the prior art, the beneficial effects of one embodiment are:

[0038] (1) In one embodiment, the air curtain device forms a barrier between the feeding tube and the inner crucible by shielding the airflow, so that even if the solid raw material flowing out of the feeding tube becomes dust floating in the air, it will first hit the shielding airflow when moving inward, and then it will be difficult to move into the inner crucible, thereby reducing the probability of dust contacting the growing single crystal silicon rod, avoiding defects and dislocations caused by dust, and thus greatly improving the quality of the produced single crystal silicon compared with the prior art;

[0039] (2) In another embodiment, by controlling v1, v2 and v3, an airflow from inside to outside is formed at the upper edge of the middle crucible (and / or at the upper edge of the inner crucible), which can prevent dust at the feeding pipe from moving inward to the single crystal silicon rod and promote the transfer of foreign matter around the single crystal silicon rod to the feeding pipe, thereby greatly improving the cleanliness of the air around the growing single crystal silicon rod and ensuring the quality of the single crystal silicon; and, according to the actual production situation, when adjusting the cooling air flow rate v2 based on the cooling demand of the thermal field and / or adjusting the feed air flow rate v1 according to the output demand and the thermal field temperature, the shielding air flow rate v3 is adjusted in a timely, rapid and accurate manner, thereby ensuring the stability of the air flow rate and flow direction at the upper edge of the middle crucible (and / or at the upper edge of the inner crucible), thereby ensuring the cleanliness of the air around the single crystal silicon rod and ensuring the quality of the single crystal silicon throughout the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1a is a schematic structural diagram of a crystal pulling system according to an embodiment of the present invention;

[0041] Figure 1b yes Figure 1a A partial enlarged view of the middle B area;

[0042] Figure 2 is a schematic structural diagram of an air curtain device and a crucible assembly of a crystal pulling system according to an embodiment of the present invention, viewed from a top view;

[0043] Figure 3 It is a schematic structural diagram of an air curtain device and a crucible assembly of a crystal pulling system according to a modified embodiment of the present invention, viewed from a top view;

[0044] Figure 4ais a schematic structural diagram of a crystal pulling system according to a modified embodiment of the present invention;

[0045] Figure 4b yes Figure 4a A partial enlarged view of the middle A area;

[0046] Figure 5 It is a module schematic diagram of a control device and various air supply devices and exhaust devices in one embodiment of the present invention. DETAILED DESCRIPTION

[0047] The technical solution of the present invention is further introduced below in conjunction with the accompanying drawings and specific implementation methods.

[0048] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0049] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0050] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] Ginseng Figure 1a and Figure 1b An embodiment of the present invention provides a crystal pulling system 100 for the continuous production of straight-pulled single crystal silicon, and can solve the technical problem of dust contacting the growing crystal rod faced in the prior art, and can greatly reduce the defects and dislocations of the single crystal silicon and improve the product quality.

[0052] In general, the crystal pulling system 100 includes a crucible assembly 10 , a feeding tube 21 , and an air curtain device 52 .

[0053] The crucible assembly 10 includes an outer crucible 11 and an inner crucible 12 .

[0054] The outer crucible 11 surrounds the outer portion of the inner crucible 12 , that is, the inner crucible 12 is located inside the outer crucible 11 , and the inner diameter of the outer crucible 11 is greater than the outer diameter of the inner crucible 12 .

[0055] A crystal growth zone 102 is formed inside the inner crucible 12, and the crystal growth zone 102 is also the region where the single crystal silicon rod is grown. That is, when preparing single crystal silicon, the seed crystal enters the melt in the inner crucible 12 and slowly rises from the melt, so that the melt solidifies on the seed crystal and grows a single crystal silicon rod.

[0056] The feeding pipe 21 is located above the crucible assembly 10, and the lower end of the feeding pipe 21 extends between the outer crucible 11 and the inner crucible 12, so that solid raw materials are added to the crucible assembly 10 through the feeding pipe 21. Specifically, the solid raw materials are added between the outer crucible 11 and the inner crucible 12 through the feeding pipe 21. In this way, in the production of single crystal silicon, after the solid raw materials added between the outer crucible 11 and the inner crucible 12 are melted, the melt eventually flows into the inner crucible 12, and the growth of single crystal silicon rods is achieved in the inner crucible 12.

[0057] As described above, in the production of single crystal silicon, when the solid raw materials of the crystal pulling system 100 are fed to the outside of the inner crucible 12 through the feeding pipe 21, if the generated dust moves inward to the inside of the inner crucible 12, it will cause defects and dislocations in the growing single crystal silicon rod.

[0058] In order to solve this technical problem, in the present application, an air curtain device 52 is added to the crystal pulling system 100 .

[0059] Specifically, the air curtain device 52 is located between the feeding tube 21 and the inner crucible 12 in the radial direction, that is, in the radial direction of the inner crucible 12 , the air curtain device 52 is located outside the inner crucible 12 and inside the feeding tube 21 .

[0060] The air curtain device 52 can supply air between the feeding tube 21 and the inner crucible 12 to form a shielding airflow surrounding the inner crucible 12. In this way, the air curtain device 52 forms a barrier between the feeding tube 21 and the inner crucible 12 through its shielding airflow, so that even if the solid raw material flowing out of the feeding tube 21 becomes dust floating in the air, it will first hit the shielding airflow when moving inward, and then it will be difficult to move into the inner crucible 12, thereby reducing the probability of dust contacting the growing single crystal silicon rod, avoiding defects and dislocations caused by dust, and thus greatly improving the quality of the produced single crystal silicon compared with the prior art.

[0061] Ginseng Figure 2 In a preferred embodiment, the air curtain device 52 may specifically include an inner cylinder 521 , an outer cylinder 522 and an air inlet passage 523 .

[0062] The inner cylinder 521 surrounds the radial outer side of the inner crucible 12 .

[0063] The outer cylinder 522 is sleeved on the outer side of the inner cylinder 521 and is spaced apart from the inner cylinder 521 .

[0064] The air intake passage 523 is defined by the inner wall of the outer cylinder 522 and the outer wall of the inner cylinder 521 . To put it another way, the gap between the outer cylinder 522 and the inner cylinder 521 constitutes at least a part of the air intake passage 523 .

[0065] From the example in the figure, the inner cylinder 521 is configured as a cylindrical cylinder structure whose inner diameter is larger than the outer diameter of the inner crucible 12, and the outer cylinder 522 is also configured as a cylindrical cylinder structure whose inner diameter is larger than the outer diameter of the inner cylinder 521, and the air inlet channel 523 is a circular annular channel radially outside the inner crucible 12 and surrounding the inner crucible 12. Accordingly, the shielding airflow flowing out of the air inlet channel 523 is roughly in a circular annular shape. Of course, the present application is not limited thereto.

[0066] Ginseng Figure 3 In a variation, the air curtain device 52 includes a plurality of air inlet pipes 520. The plurality of air inlet pipes 520 surround the inner crucible 12 in a radial direction, that is, any air inlet pipe 520 is located in a radial direction outside the inner crucible 12, and the air inlet pipes 520 are arranged in a circumferential direction. Thus, the airflows blown out from the air inlet pipes 520 form a circular air curtain around the inner crucible 12 as a whole, that is, the shielding airflow.

[0067] pass Figure 2 and Figure 3 Two different implementations of the air curtain device 52 are illustrated, but it can be understood that under the technical purpose of the present application, the specific structure of the air curtain device 52 is not limited thereto, and any feasible method in the art to construct a shielding airflow around the inner crucible 12 does not deviate from the technical purpose of the present application.

[0068] Furthermore, in one embodiment, the crucible assembly 10 is specifically configured as a three-layer structure.

[0069] For example, Figures 1a to 3 In addition to the inner crucible 12 and the outer crucible 11 , the crucible assembly 10 further includes a middle crucible 13 , which is surrounded between the inner crucible 12 and the outer crucible 11 .

[0070] The inner wall of the outer crucible 11 and the outer wall of the middle crucible 13 jointly define a melting zone 101, the inner wall of the middle crucible 13 and the outer wall of the inner crucible 12 jointly define a transition zone 103, and the melting zone 101 and the crystal growth zone 102 are connected via the transition zone 103. For example, the melting zone 101 and the transition zone 103 are connected by an opening at the bottom of the middle crucible 13, and the melting zone 101 and the crystal growth zone 101 are connected by an opening at the bottom of the inner crucible 12.

[0071] The feeding tube 21 extends downward toward the melting zone 101 , that is, the solid raw material fed by the feeding tube 21 directly enters the melting zone 101 and melts in the melting zone 101 , and then the melt flows into the transition zone 103 and then into the crystal growth zone 101 to grow into a single crystal silicon rod in the crystal growth zone 101 .

[0072] Furthermore, the air curtain device 52 is radially located between the outer crucible 11 and the middle crucible 13, so that the shielding airflow is formed just above the transition zone 103. In this way, on the one hand, the shielding airflow formed can prevent the dust on the upper part of the melting zone 101 from entering the inner crucible 12, thereby ensuring the quality of the grown single crystal silicon rods; on the other hand, the shielding airflow formed can be located above the transition zone 103 and appropriately away from the melting zone 101, thereby preventing the shielding airflow from causing the formation of a chaotic airflow above the melting zone 101, thereby stabilizing the stability of the dust above the melting zone 101.

[0073] In this embodiment, preferably, the lower end of the air curtain device 52 can be set to be lower than at least one of the upper edge of the inner crucible 12 and the upper edge of the middle crucible 13. In this way, not only can the diffusion direction of the shielding airflow be appropriately limited, but also a physical barrier can be constructed by the air curtain device 52 itself to prevent dust from moving from the outside to the inside of the inner crucible 12. For example, when the dust moves inward in a disorderly manner, it will hit the air curtain device 52, and it will be difficult to move into the inner crucible 12.

[0074] Of course, the present application is not limited thereto. For example, the air curtain device 52 may also be higher than the upper edge of the inner crucible 12 and the upper edge of the middle crucible 13 as a whole, so as to shield the airflow.

[0075] The above describes a three-layer crucible assembly 10 structure, but the structure of the crucible assembly 10 of the present application is not limited thereto. Figure 4a and Figure 4b A two-layer crucible assembly 10 structure is shown.

[0076] Specifically, in Figure 4a and Figure 4bIn a variation shown in the figure, the inner wall of the outer crucible 11 and the outer wall of the inner crucible 12 together define a melting zone 101 , and the melting zone 101 and the crystal growth zone 102 are connected through an opening at the bottom of the inner crucible 12 .

[0077] The feeding tube 21 extends downward toward the melting zone 101 , and a shielding airflow is formed directly above the melting zone 101 , so that the shielding airflow can be used to prevent dust around the feeding tube 21 from moving inward to the interior of the inner crucible 12 .

[0078] In this embodiment, preferably, the lower end of the air curtain device 52 can be set to be lower than the upper edge of the inner crucible 12. Therefore, the air curtain device 52 itself can be used to form a physical barrier to prevent dust from moving from the outside to the inside of the inner crucible 12. Of course, the air curtain device 52 can also be higher than the upper edge of the inner crucible 12 as a whole.

[0079] certainly, Figure 1a and Figure 4a Each of the figures illustrates an optional specific structure of the crucible assembly 10 , but the structure of the crucible assembly 10 is not limited thereto, and can also be implemented with other feasible structures in the art.

[0080] Next, Figures 1a to 3 Or Figure 4a and Figure 4b , combined with Figure 5 The crystal pulling system 100 further includes a first gas supply device 22 , a second gas supply device 32 , a guide tube 41 , a third gas supply device 54 and a control device 90 .

[0081] The first gas supply device 22 is connected to the feeding pipe 21 to supply a feeding airflow to the feeding pipe 21. It can be understood that the feeding airflow can flow downward along the feeding pipe 21, thereby driving the solid material in the feeding pipe 21 to be quickly added to the crucible assembly 10.

[0082] The second gas supply device 32 is used to supply cooling air flow to the top of the crucible assembly 10 .

[0083] The guide tube 41 is matched with the second gas supply device 32 and is axially located between the second gas supply device 32 and the crucible assembly 10 , and guides the cooling gas flow to the middle of the inner crucible 12 .

[0084] In this way, through the arrangement of the second gas supply device 32 and the guide tube 41, the cooling airflow provided by the second gas supply device 32 can flow downward into the inner crucible 12 under the guidance of the guide tube 41, so that, on the one hand, a relatively low temperature area is formed above the crystal growth zone 102 of the inner crucible 12 to provide growth power for crystal growth; on the other hand, the cooling airflow can be guided into the heat field to effectively cool the crystal rod and accelerate the release of latent heat of crystallization.

[0085] The third air supply device 54 is connected to the air curtain device 52 to supply shielding airflow to the air curtain device 52 .

[0086] The control device 90 is electrically connected to the first air supply device 22, the second air supply device 32 and the third air supply device 54, and can control the first air supply device 22, the second air supply device 32 and the third air supply device 54. For example, it controls the start, stop and operation status of the first air supply device 22, the second air supply device 32 and the third air supply device 54.

[0087] In a preferred embodiment, the first air supply device 22, the second air supply device 32 and the third air supply device 54 can be specifically configured as air flow drivers such as fans and air pumps, which can generate negative pressure or positive pressure to drive the generation of airflow, and can also controllably adjust the operating state to change the flow rate of the supplied airflow, for example, the fan increases the airflow rate by increasing the rotation speed. However, the present application is not limited to this, and any device that can drive the flow of airflow and can adjust the flow rate of airflow can be applied to the present application to construct the first air supply device 22, the second air supply device 32 and the third air supply device 54.

[0088] In one embodiment, the control device 90 controls the feed airflow velocity v1 of the first air supply device 22, the cooling airflow velocity v2 of the second air supply device 32, and the shielding airflow velocity v3 of the third air supply device 54, so that an airflow from the inside to the outside is formed at the upper edge of the middle crucible 13. Thus, not only can the shielding airflow be used to block the inward movement of dust, but also, an airflow is formed on the upper part of the crucible assembly 10 as a whole, which flows radially outward from the growing single crystal silicon rod, over the inner crucible 12 and the middle crucible 13, and then flows to the outside of the middle crucible 13, thereby preventing the dust at the feeding pipe 21 from moving inward to the single crystal silicon rod, and promoting the transfer of foreign matter around the single crystal silicon rod to the feeding pipe 21, greatly improving the cleanliness of the air around the growing single crystal silicon rod, and ensuring the quality of the single crystal silicon.

[0089] Furthermore, the control device 90 controls the feed air flow rate v1 of the first air supply device 22, the cooling air flow rate v2 of the second air supply device 32, and the shielding air flow rate v3 of the third air supply device 54 so that the three satisfy 0.4v2 2 -0.8v2+0.2v3 2 -0.3v3-0.5v1 2 +v1-1≥k.

[0090] Where k ≥ 0 and is a constant, and the unit of v1, v2 and v3 is m / s.

[0091] So, when 0.4v2 2 -0.8v2+0.2v3 2 -0.3v3-0.5v1 2When the condition of +v1-1≥k≥0 is met, an airflow from the inside to the outside is formed at the upper edge of the middle crucible 13 (and / or at the upper edge of the inner crucible 12), which can prevent the dust at the feeding pipe 21 from moving inward to the single crystal silicon rod, and promote the transfer of foreign matter around the single crystal silicon rod to the feeding pipe 21, thereby greatly improving the air cleanliness around the growing single crystal silicon rod and ensuring the quality of the single crystal silicon; and, based on the design of this relationship, when adjusting the cooling airflow velocity v2 based on the cooling demand of the thermal field and / or adjusting the feeding airflow velocity v1 according to the output demand and the thermal field temperature (it can be understood that the change in the feeding airflow velocity can change the feeding amount) according to the actual production situation, the shielding airflow velocity v3 can be adjusted in time, quickly and accurately, thereby ensuring the stability of the airflow velocity and flow direction at the upper edge of the middle crucible 13, and thus ensuring the air cleanliness around the single crystal silicon rod throughout the production process and ensuring the quality of the single crystal silicon.

[0092] Preferably, under the control of the control device 90, the feed air flow rate v1, the cooling air flow rate v2, and the shielding air flow rate v3 can also satisfy 0.4v2 2 -0.8v2+0.2v3 2 -0.3v3-0.5v1 2 +v1-1≤k1.

[0093] Wherein, k<k1≤10 and k1 is a constant, preferably, k1≤8, and more preferably, k1≤5. In this way, not only can a stable airflow from inside to outside be formed at the upper edge of the middle crucible 13, solving the problem of dust contacting the growing single crystal silicon rod, but also the flow rate of the airflow can be controlled and stable, avoiding excessive airflow speed, that is, avoiding strong and rapid turbulence, thereby facilitating the stability of the thermal field and the liquid level stability of the melt, and ensuring the success rate of crystal pulling and production efficiency.

[0094] In one embodiment, 0.4v2 2 -0.8v2+0.2v3 2 -0.3v3-0.5v1 2 +v1-1 can roughly represent the flow rate of the gas flow from inside to outside formed at the upper edge of the middle crucible 13 (and / or at the upper edge of the inner crucible 12), and the unit is m / s. Through the definition of k and k1, that is, the upper edge of the middle crucible 13 not only forms a gas flow from inside to outside, but also has a flow rate between 0 and 10 m / s, or preferably between 0 and 8 m / s, or even between 0 and 5 m / s.

[0095] Furthermore, the crystal pulling system 100 further includes a furnace body 60 and a support base 70 .

[0096] The furnace body 60 forms a furnace cavity inside to accommodate other components and construct a production site. The support seat 70, the crucible assembly 10, the feeding pipe 21, the air curtain device 52 and the guide tube 41 are arranged in the furnace cavity.

[0097] The support seat 70 is rotatably connected to the furnace body 60 around the central axis of the crucible assembly 10 . The crucible assembly 10 can be fixedly supported on the support seat 70 and can rotate together with the support seat 70 .

[0098] The upper end of the guide tube 41 can be fixedly connected to the furnace body 60 and suspended above the crucible assembly 10 ; the lower end of the guide tube 41 extends to the interior of the inner crucible 12 .

[0099] In one embodiment, the inner side surface of the guide tube 41 is in an inverted cone shape, that is, the upper diameter is large and the lower diameter is small, so as to guide the cooling air flow supplied by the second gas supply device 32 downward to the middle of the inner crucible 12 .

[0100] Furthermore, the crystal pulling system 100 may also include a gas supply pipeline 31. The gas supply pipeline 31 may be fixed to the top of the furnace body 60 and extend vertically directly above the center of the inner crucible 12. The second gas supply device 32 is connected to the gas supply channel 31. In this way, the cooling airflow supplied by the second gas supply device 32 flows downward along the gas supply channel 31 into the furnace cavity in the furnace body 60, and flows to the middle of the inner crucible 12 under the guidance of the guide tube 41.

[0101] In one embodiment, the cooling gas flow, feed gas flow and shielding gas flow are all inert gases, such as argon.

[0102] Furthermore, the crystal pulling system 100 may further include a support ring 42 . The support ring 42 is fixedly sleeved on the outer circumference of the guide tube 41 and is covered above the crucible assembly 10 .

[0103] In one embodiment, the feeding tube 21 and the air curtain device 52 can be fixedly arranged on the support ring 42, and can extend downward from the support ring 42 toward the crucible assembly 10. Of course, the present application is not limited thereto, and can be implemented as any assembly structure that can achieve the fixing of the feeding tube 21 and the air curtain device 52.

[0104] In addition, the support ring 42 can also be sealed and matched with the guide tube 41 to form a cover located above the crucible assembly 10. The cover can prevent the gas between the crucible assembly 10 and the cover from flowing upward over the cover to the top of the furnace chamber, that is, it limits the gas to only bend and flow under the cover.

[0105] Furthermore, the crystal pulling system 100 may further include an exhaust pipeline 51 and an exhaust device 53 for exhausting the gas in the furnace chamber out of the furnace chamber and maintaining a stable gas pressure in the furnace chamber.

[0106] Preferably, the exhaust pipe 51 has an air inlet and an air outlet.

[0107] The gas inlet is located above the melting zone 101 and radially between the feeding pipe 21 and the outer crucible 11, that is, the gas inlet is open toward the melting zone 101. In the figure, the gas inlet is also the lower end of the exhaust pipe 51.

[0108] The gas outlet is communicated with the outside of the furnace body 60 .

[0109] The exhaust device 53 is connected to the exhaust pipeline 51 and is used to form an exhaust airflow from the air inlet to the air outlet.

[0110] In this way, through the setting of the exhaust pipe 51 and the exhaust device 53, not only can the gas in the furnace chamber be discharged out of the furnace chamber and the air pressure in the furnace chamber be maintained stable; but also through the position setting of the air inlet of the exhaust pipe 51, the dust above the melting zone 101 can be promoted to be discharged out of the furnace chamber, thereby further improving the cleanliness around the growing single crystal silicon, improving the success rate of crystal pulling and product quality.

[0111] In one embodiment, the exhaust device 53 can be specifically configured as an airflow driver such as a fan or an air pump, which can generate negative pressure or positive pressure to drive the airflow, and can also controllably adjust the operating state to change the flow rate of the exhaust airflow. For example, the control device 90 is electrically connected to the exhaust device 53 and controls the start, stop and operating state of the exhaust device, so as to maintain a constant air pressure in the furnace chamber, for example, at about 1000Pa.

[0112] In one embodiment, the exhaust device 53 may also be fixedly disposed on the support ring 42, and may extend downward from the support ring 42 toward the crucible assembly 10. Of course, the present application is not limited thereto.

[0113] Next, one embodiment further provides a control method for the crystal pulling system 100 .

[0114] Specifically, the control method includes:

[0115] Controlling the first air supply device 22 to supply a feed air flow with a flow rate v1 to the feed pipe 21;

[0116] Control the second gas supply device 32 to supply a cooling gas flow with a flow rate v2, and make the cooling gas flow flow from top to bottom toward the crystal growth area 102;

[0117] Control the third air supply device 54 to supply air to the air curtain device 52 at an air flow rate v3;

[0118] Among them, 0.4v2 2 -0.8v2+0.2v3 2 -0.3v3-0.5v12 +v1-1≥k, k≥0 and is a constant, the unit of v1, v2 and v3 is m / s.

[0119] In this way, the control method can form an airflow from the inside to the outside at the upper edge of the middle crucible 13 (and / or at the upper edge of the inner crucible 12) by controlling v1, v2 and v3, which can prevent the dust at the feeding pipe 21 from moving inward to the single crystal silicon rod, and promote the transfer of foreign matter around the single crystal silicon rod to the feeding pipe 21, thereby greatly improving the air cleanliness around the growing single crystal silicon rod and ensuring the quality of the single crystal silicon; and, according to the actual production situation, when adjusting the cooling air flow rate v2 based on the cooling demand of the thermal field and / or adjusting the feeding air flow rate v1 according to the output demand and the thermal field temperature, the shielding air flow rate v3 can be adjusted in time, quickly and accurately to ensure that the air flow rate and flow direction of the air flow at the upper edge of the middle crucible 13 (and / or at the upper edge of the inner crucible 12) are stable, thereby ensuring the air cleanliness around the single crystal silicon rod throughout the production process and ensuring the quality of the single crystal silicon.

[0120] Furthermore, the relationship between v1, v2 and v3 also satisfies 0.4v2 2 -0.8v2+0.2v3 2 -0.3v3-0.5v1 2 +v1-1≤k1.

[0121] Wherein, k<k1≤10 and k1 is a constant, preferably, k1≤8, and more preferably, k1≤5. In this way, not only can a stable airflow from inside to outside be formed at the upper edge of the middle crucible 13 (and / or at the upper edge of the inner crucible 12), solving the problem of dust contacting the growing single crystal silicon rod, but also the flow rate controllability and stability of the airflow can be ensured, avoiding excessive airflow speed, that is, avoiding strong and rapid turbulence, thereby facilitating the stability of the thermal field and the liquid level stability of the melt, and ensuring the success rate of crystal pulling and production efficiency.

[0122] In one embodiment, the flow rate v1 can be characterized as the air flow rate of the exhaust port of the first air supply device 22, the flow rate setting value of the first air supply device 22, etc., the flow rate v2 can be characterized as the air flow rate of the exhaust port of the second air supply device 32, the flow rate setting value of the second air supply device 32, etc., and the flow rate v3 can be characterized as the air flow rate of the exhaust port of the third air supply device 54, the flow rate setting value of the third air supply device 54, etc. However, the present application is not limited thereto.

[0123] Furthermore, the control device 90 may specifically include a collector, a memory and a processor.

[0124] The collector can specifically be an input device such as a keyboard, touch screen, touchpad, mouse, camera, microphone, sensor, etc., which can be used to at least collect flow velocities v1, v2 and v3, and can also be used to collect the air pressure value in the furnace cavity.

[0125] The memory may be used to store various collected data, including but not limited to flow rates v1, v2 and v3, the gas pressure value, and may also store programs for operation of the crystal pulling system 100, such as various step programs of the control method of the crystal pulling system 100. The memory may be specifically configured as a read-only memory (ROM), a random access memory (RAM), and the like.

[0126] The processor can read data from the memory and execute various programs in the memory. The processor can specifically be a central processing unit, a graphics processing unit, etc.

[0127] The control device 90 may be integrated into one electronic device or distributed in different electronic devices. For example, the control device 90 may be partially or completely integrated into an industrial computer, PLC or other device for implementation, but is not limited thereto.

[0128] In addition, other configurations and operations of the crystal pulling system 100 according to the embodiment of the present invention are known to those skilled in the art and will not be described in detail herein.

[0129] In summary, the present invention has the following beneficial effects: the wind curtain device 52 forms a barrier between the feeding tube 21 and the inner crucible 12 by shielding the airflow, so that even if the solid raw material flowing out of the feeding tube 21 becomes dust floating in the air, it will first collide with the shielding airflow when moving inward, and then it will be difficult to move into the inner crucible 12, thereby reducing the probability of dust contacting the growing single crystal silicon rod, avoiding defects and dislocations caused by dust, and thus greatly improving the quality of the produced single crystal silicon compared with the prior art.

[0130] In the description of this specification, the description with reference to the terms "an implementation mode", "an embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0131] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A crystal pulling system, comprising: A crucible assembly, comprising an outer crucible and an inner crucible, wherein the outer crucible surrounds the outside of the inner crucible, and the interior of the inner crucible forms a crystal growth zone; A feeding pipe, which is located above the crucible assembly and has a lower end extending between the outer crucible and the inner crucible; characterized in that the crystal pulling system further includes: An air curtain device is located between the feeding tube and the inner crucible in the radial direction, and is used for supplying air between the feeding tube and the inner crucible to form a shielding airflow surrounding the inner crucible.

2. The crystal pulling system according to claim 1, characterized in that: The air curtain device includes a plurality of air inlet pipes, and the plurality of air inlet pipes circumferentially surround the radial outer side of the inner crucible; Alternatively, the air curtain device comprises: An inner cylinder surrounding the radially outer side of the inner crucible; an outer cylinder, which is sleeved on the outer side of the inner cylinder and spaced apart from the inner cylinder; and An air intake passage is defined by the inner wall of the outer cylinder and the outer wall of the inner cylinder.

3. The crystal pulling system according to claim 1 or 2, characterized in that: The inner wall of the outer crucible and the outer wall of the inner crucible jointly define a melting zone, and the melting zone and the crystal growth zone are connected through an opening at the lower part of the inner crucible; the feeding pipe extends downward toward the melting zone, and the shielding airflow is formed directly above the melting zone; Alternatively, the crucible assembly also includes a middle crucible, which is surrounded by the inner crucible and the outer crucible, the inner wall of the outer crucible and the outer wall of the middle crucible jointly define a melting zone, the inner wall of the middle crucible and the outer wall of the inner crucible jointly define a transition zone, the melting zone and the crystal growth zone are connected via the transition zone; the feeding pipe extends downward toward the melting zone, and the wind curtain device is radially located between the outer crucible and the middle crucible, so that the shielding airflow is formed directly above the transition zone.

4. The crystal pulling system according to claim 3, characterized in that: The lower end of the air curtain device is lower than at least one of the upper edge of the inner crucible and the upper edge of the middle crucible.

5. The crystal pulling system according to claim 3, characterized in that: The crystal pulling system further comprises: A first air supply device, which is connected to the feeding pipe to supply a feed air flow to the feeding pipe; a second gas supply device, used for supplying a cooling gas flow to the top of the crucible assembly; a guide tube, which is axially located between the exhaust port of the second gas supply device and the crucible assembly and guides the cooling gas flow to the middle of the inner crucible; a third air supply device, which is connected to the air curtain device to supply a shielding airflow to the air curtain device; A control device is electrically connected to and controls the first air supply device, the second air supply device and the third air supply device.

6. The crystal pulling system according to claim 5, characterized in that: The control device controls the feed air flow rate v1 of the first gas supply device, the cooling air flow rate v2 of the second gas supply device, and the shielding air flow rate v3 of the third gas supply device, so that an airflow from the inside to the outside is formed at the upper edge of the inner crucible or the upper edge of the middle crucible.

7. The crystal pulling system according to claim 5, characterized in that: The feed air flow rate v1 of the first air supply device, the cooling air flow rate v2 of the second air supply device, and the shielding air flow rate v3 of the third air supply device meet 0.4v2 2 -0.8v2+0.2v3 2 -0.3v3-0.5v1 2 +v1-1≥k; Where k ≥ 0 and is a constant, and the unit of v1, v2 and v3 is m / s.

8. The crystal pulling system according to claim 5, characterized in that: The crystal pulling system further comprises: A furnace body, wherein a furnace cavity is formed inside the furnace body, and the crucible assembly, the feeding pipe, the air curtain device and the guide tube are arranged in the furnace cavity; an exhaust pipeline having an air inlet and an air outlet, wherein the air inlet is located above the melting zone and radially between the feeding pipe and the outer crucible, and the air outlet is connected to the outside of the furnace body; An exhaust device is connected to the exhaust pipeline and is used to form an exhaust air flow from the air inlet to the air outlet.

9. A control method for a crystal pulling system according to any one of claims 1 to 8, characterized in that: The control method comprises: Controlling the first air supply device to supply a feed air flow with a flow rate v1 to the feed pipe; Control the second gas supply device to supply a cooling gas flow with a flow rate v2, and make the cooling gas flow flow from top to bottom toward the crystal growth area; Control the third air supply device to supply air to the air curtain device at an air flow rate v3; Among them, 0.4v2 2 -0.8v2+0.2v3 2 -0.3v3-0.5v1 2 +v1-1≥k, k≥0 and is a constant, the unit of v1, v2 and v3 is m / s.

10. The control method of the crystal pulling system according to claim 9, characterized in that: 0.4v2 2 -0.8v2+0.2v3 2 -0.3v3-0.5v1 2 +v1-1≤k1, k1≤5 and is a constant.

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