Continuous crystal growth method and system

Abstract

The invention provides a continuous crystal growth method and system, and the method comprises the steps: selecting a corresponding quartz crucible according to the size of a single crystal to be drawn, and controlling the distance between the edge of the single crystal and the inner wall of the quartz crucible to be greater than a distance preset value; and in the equal-diameter stage, continuous re-feeding is carried out, and the rotating speed of the quartz crucible, the rotating speed of the single crystal and the position of the quartz crucible are controlled, so that stable growth of the single crystal is controlled. The method has the beneficial effects that the single crystal quality can be effectively improved, the resistivity consistency is improved, the optimal resistivity interval proportion is increased, and the product efficiency is improved; the damage to the stability of a crystal growth area in the continuous re-feeding process can be effectively solved, the crystal growth survival rate is increased, and the feasibility of the continuous re-feeding technology is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of silicon single crystal preparation, and particularly relates to a method and system for continuous crystal growth. Background Art

[0002] As the main method for preparing single crystal silicon, due to the resistivity segregation characteristics, during the pulling process of a single crystal silicon rod, as the molten material gradually decreases, impurity deposition causes the resistivity to decay rapidly, severely limiting the length of the pulled single crystal. The proportion of the high-efficiency resistivity range is relatively small, affecting the resistivity concentration and the efficiency performance at the battery end. Currently, in the industry, the method of taking segments and re-investing is usually used to shorten the length of each single crystal and pull multiple single crystals to solve the resistivity decay, improve the resistivity concentration, increase the proportion of the high-efficiency resistivity range, and improve the battery end efficiency.

[0003] After the traditional re-investment technology completes the crystal pulling production of one batch of raw materials, a lot of complicated and ineffective work needs to be done to prepare for the production of a new batch, including processes such as cooling, taking the single crystal, feeding materials, melting materials, stabilizing the temperature, seeding, and shoulder broadening. These complicated preliminary works lead to an increase in non-effective crystal growth working hours, seriously affecting the production efficiency and production cost of single crystal silicon. Currently, the market has started to use the CCZ continuous growth technology to achieve continuous feeding during the crystal growth process, effectively solving the related technical bottlenecks of the pulled rod length and product quality. However, limited by the current CCZ technology's auxiliary material cost and the technical bottleneck of auxiliary materials that has not been overcome, there is currently no CCZ continuous re-investment technology in the industry that can carry out mass production. Summary of the Invention

[0004] In view of the above problems, the present invention provides a method and system for continuous crystal growth to solve the above or other previous problems existing in the prior art.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: A method for continuous crystal growth, including,

[0006] According to the size of the single crystal to be pulled, select the corresponding quartz crucible, and control the distance between the edge of the single crystal and the inner wall of the quartz crucible to be greater than a preset value;

[0007] Perform crystal pulling. During the equal diameter stage, perform continuous re-investment, and control the rotation speed of the quartz crucible, the rotation speed of the single crystal, and the position of the quartz crucible to control the stable growth of the single crystal.

[0008] Further, the preset value of the distance is 340 mm.

[0009] Further, the distance between the edge of the single crystal and the quartz crucible includes a crystal formation area distance and a feeding area distance sequentially arranged along the direction from the edge of the single crystal to the inner wall of the quartz crucible, and control the crystal formation area distance to be greater than the first preset value of the distance.

[0010] Further, the preset value of the first distance is 270 mm.

[0011] Further, during the continuous refeeding process, the position of the quartz crucible is controlled to be unchanged.

[0012] Further, continuous refeeding starts from the initial stage of the isodiametric stage. During the continuous refeeding process, the distance between the liquid outlet and the crucible is controlled to be unchanged, and the distance between the liquid outlet and the crucible is 10 - 50 mm.

[0013] Further, in the isodiametric stage, when the length of the single crystal is greater than the first length, continuous refeeding starts. During the continuous refeeding process, the distance between the liquid outlet and the crucible is controlled to be unchanged. The first length is 50 mm, and the distance between the liquid outlet and the crucible is 10 - 50 mm.

[0014] Further, doping is carried out synchronously during the continuous refeeding process, and the distance from the liquid surface of the silicon melt to the upper edge of the quartz crucible is controlled to be unchanged, so that the doping amount of the dopant in the silicon melt satisfies the segregation law required for single crystal production.

[0015] Further, in the isodiametric stage, when the length of the single crystal is greater than the first length, continuous refeeding starts, the distance between the liquid outlet and the crucible is controlled to be unchanged, and the quartz crucible is controlled to rise, so that the doping amount of the dopant in the silicon melt satisfies the segregation law required for single crystal production.

[0016] Further, the first length is 50 mm, and the distance between the liquid outlet and the crucible is 10 - 50 mm.

[0017] Further, the rotation speed of the quartz crucible is greater than 4 rpm, and the rotation speed of the single crystal is less than 16 rpm.

[0018] Further, during the continuous refeeding process, the flow rate of the protective gas and the furnace pressure of the single crystal furnace are also controlled to control the stable growth of the single crystal.

[0019] Further, the flow rate of the protective gas is greater than 40 slpm, and the furnace pressure of the single crystal furnace is less than 30 torr.

[0020] Further, when carrying out continuous refeeding, a continuous refeeding device is used for refeeding, and the particle size of the refeed material is less than 10 mm.

[0021] A continuous crystal growth system includes a single crystal furnace device and a continuous refeeding device arranged outside the single crystal furnace device. The continuous refeeding device is communicated with the single crystal furnace device so that the refeed material in the continuous refeeding device can enter the single crystal furnace device for continuous refeeding of the refeed material; the single crystal furnace device includes a quartz crucible, and the quartz crucible is arranged such that the distance between the edge of the single crystal to be drawn and the inner wall of the quartz crucible is greater than the preset distance value.

[0022] Further, the preset distance value is 340 mm.

[0023] Further, the furnace device includes a partition component. The partition component is provided with a partition part extending into the silicon melt. The partition part is located between the single crystal and the inner wall of the quartz crucible, so that the silicon melt is divided into a crystal formation area and a feeding area.

[0024] Further, the distance between the partition part and the edge of the single crystal is greater than a preset first distance value, and the preset first distance value is 270 mm.

[0025] Further, the partition component is arranged inside the quartz crucible; or, the partition component is detachably connected to the guide cylinder, and the partition component and the guide cylinder are coaxially arranged.

[0026] Further, the partition component is provided with a feeding hole corresponding to the feeding area of the silicon melt, so that when re-feeding, the re-fed material enters the feeding area of the silicon melt through the feeding hole.

[0027] Further, the partition component is provided with a shielding part located outside the carbon-carbon crucible, and the shielding part is arranged along the axial direction of the quartz crucible.

[0028] Further, the single crystal furnace device includes a guide component arranged inside the quartz crucible. The guide component is detachably connected to the continuous re-feeding device, and the guide component is arranged along the axial direction of the quartz crucible. The guide component corresponds to the discharge port of the continuous re-feeding device to guide the re-fed material entering the quartz crucible.

[0029] Further, the guide component includes a guide tube. The feeding end of the guide tube has a variable diameter structure, and the discharging end of the guide tube has an inclined mouth structure.

[0030] Further, the inclination angle of the inclined mouth structure is not greater than 45°.

[0031] Due to the adoption of the above technical solutions, before crystal pulling, according to the size of the single crystal to be pulled, a quartz crucible of a corresponding size is selected, and the distance between the edge of the single crystal and the inner wall of the quartz crucible is controlled to be greater than the preset distance value. And during the crystal pulling process, in the isodiametric stage, continuous re-feeding is carried out, and the position of the quartz crucible is controlled to be unchanged. At the same time, the rotation speed of the quartz crucible and the rotation speed of the single crystal are controlled, so that during continuous re-feeding, the re-fed material falls into the feeding area of the silicon melt in the quartz crucible, reducing the impact on the Taylor column area during the re-feeding process, maintaining the stable melt area required for crystal growth, enhancing the stability of crystal growth during crystal pulling, which can not only solve the resistivity attenuation, improve the resistivity concentration, increase the proportion of the high-efficiency resistivity range, improve the cell end efficiency, but also realize continuous crystal growth, thereby increasing the effective crystal growth working hours and increasing the output;

[0032] By adopting this continuous crystal growth method, the quality of single crystals can be effectively improved, the resistivity consistency can be enhanced, the proportion of the optimal resistivity range can be increased, and the product efficiency can be improved; it can effectively solve the damage to the stability of the crystal growth area during the continuous recharging process, improve the crystal growth survival rate, and realize the feasibility of the continuous recharging technology; it can effectively reduce the ineffective crystal growth time such as recharging, slow temperature reduction, segment extraction, temperature stabilization, crystal seeding, and shoulder expansion, and increase the output; it can effectively improve the oxygen content of single crystals. A large crucible diameter ratio promotes the volatilization of oxygen content, reduces the oxygen content of the crystal, and at the same time, the melt height remains unchanged, which helps to solve the problems of the increase in the oxygen content at the tail of the crystal bar and the poor crystal formation at the tail.

[0033] A separation component is provided, which can effectively separate the crystal growth area of the silicon melt from the feeding area, reduce the melt fluctuation caused by the recharged material dropping to the liquid surface during the continuous recharging process. The separation component is provided with a feeding hole, which can realize the entry of the recharged material and the volatilization of the oxygen content of the melt liquid surface.

[0034] A diversion component is provided to receive the recharged material output by the continuous recharging device, so that the recharged material moves along the diversion component, preventing the recharged material from splashing outside the crystal growth area during feeding and damaging the stability during the crystal growth process. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic structural diagram of the crystal growth area and the feeding area between the quartz crucible and the single crystal in an embodiment of the present invention;

[0036] Figure 2 It is a schematic structural diagram of a single crystal furnace device provided with a separation component in an embodiment of the present invention;

[0037] Figure 3 It is Figure 2 a top view structural diagram of a separation component of one of the structures in

[0038] Figure 4 It is Figure 2 a cross-sectional structural diagram of a separation component of one of the structures in

[0039] Figure 5 It is a schematic structural diagram of another single crystal furnace device provided with a separation component in an embodiment of the present invention;

[0040] Figure 6 It is Figure 5 a top view structural diagram of another separation component of one of the structures in

[0041] Figure 7 It is Figure 5 a cross-sectional structural diagram of another separation component of one of the structures in

[0042] Figure 8 It is a schematic structural diagram of a single crystal furnace device provided with a diversion component in an embodiment of the present invention;

[0043] Figure 9 It is a schematic structural diagram of the diversion component of an embodiment of the present invention.

[0044] In the figure:

[0045] 1. Quartz crucible 2. Single crystal 3. Continuous recharging device

[0046] 4. Partition component 400. Support part 401. Partition part

[0047] 402. Feeding hole 403. Shielding part 5. Diversion component

[0048] 500. Pipe main body 501. Feed end 502. Discharge end Detailed implementation manners

[0049] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0050] Figure 1 A schematic structural diagram of an embodiment of the present invention is shown. This embodiment relates to a method and system for continuous crystal growth, which is used in the process of pulling single crystals directly. According to the size of the single crystal to be pulled, a quartz crucible with a corresponding size is selected, the distance between the edge of the single crystal and the inner wall of the quartz crucible is controlled, and continuous recharging is carried out in the isodiameter stage. By controlling the crystal rotation speed and the crucible rotation speed, continuous feeding during the crystal growth process is realized, effectively solving the problems of the length of the pulled rod and the product quality. At the same time, the stability during the continuous crystal growth process is realized, which is convenient for mass production promotion and cost reduction.

[0051] A method for continuous crystal growth, which is used in the process of directly pulling single crystal 2, realizes continuous crystal growth and maintains the stability during the continuous crystal growth process. As Figure 1 shown, it includes,

[0052] According to the size of the single crystal 2 to be pulled, a corresponding quartz crucible 1 is selected, and the distance between the edge of the single crystal 2 and the inner wall of the quartz crucible 1 is controlled to be greater than a preset value. Before the crystal pulling starts, that is, before loading, according to the diameter size of the single crystal 2 to be pulled, a corresponding quartz crucible 1 is selected. When the quartz crucible 1 is selected, its size is set such that the distance between the edge of the single crystal 2 and the inner wall of the quartz crucible 1 is greater than the preset value, so as to ensure the crystal formation area distance and the feeding area distance in the silicon melt of the quartz crucible 1, reduce the impact of the recharged material on the Taylor column area during the recharging process, enhance the crystal growth stability during the crystal pulling process, increase the crucible diameter ratio (the ratio of the diameter of the quartz crucible 1 to the diameter of the single crystal 2), which is beneficial to the volatilization of SIO and reduces the oxygen content of the crystal bar;

[0053] Crystal pulling is carried out. During the equal-diameter stage, continuous multiple feeding is performed, and the rotation speed of the quartz crucible 1, the rotation speed of the single crystal 2, and the position of the quartz crucible 1 are controlled so that the rotation speed of the quartz crucible 1 is coordinated with the rotation speed of the single crystal 2, and combined with the position of the quartz crucible 1 to control the stable growth of the single crystal 2.

[0054] Currently, during the crystal pulling process, there are mainly four convection modes in the silicon melt in the quartz crucible 1: surface tension convection, thermal convection, forced convection, and natural convection. During the actual crystal growth process, the crystal and the quartz crucible 1 perform relative motion, forming a Taylor column region below the solid-liquid interface. The formation of the Taylor column hinders the diffusion of melt impurities and forms a relatively stable region below the crystal growth region, which is beneficial to the stable growth of the crystal.

[0055] Therefore, by controlling the distance between the edge of the single crystal 2 and the inner wall of the quartz crucible 1, compared with the existing crystal pulling process, increasing the distance between the edge of the single crystal 2 and the inner wall of the quartz crucible 1, increasing the crucible diameter ratio, and combining continuous multiple feeding to reduce the impact of the multiple feed material on the Taylor column region during the multiple feeding process can effectively increase the stability of the Taylor column region and improve the survival rate of continuous multiple feeding and continuous crystal growth.

[0056] Specifically, in the crystal pulling system, the quartz crucible 1 is filled with silicon melt, and during the crystal pulling process, the single crystal 2 and the quartz crucible 1 are coaxially arranged. The distance from the edge of the above-mentioned single crystal 2 to the inner wall of the quartz crucible 1 is; among the inner walls corresponding to both ends of any diameter line of the quartz crucible 1, the distance from the end point of the diameter line of the single crystal 2 that coincides with this diameter of the quartz crucible 1 to the inner wall of the quartz crucible 1 opposite to this end point, that is, Figure 1 The distance represented by H1 in, and the distances from each point on the circumference of the single crystal 2 to the inner wall of the quartz crucible 1 opposite to this point are all the same.

[0057] Select a quartz crucible 1 with a larger size. Then, for pulling a single crystal 2 of the same size, the larger the crucible diameter ratio, the more it can reduce the impact of the multiple feed material on the Taylor column region during the multiple feeding process, the more it can enhance the stability of crystal growth during the crystal pulling process, and at the same time, it is beneficial to the volatilization of SIO and reduces the oxygen content of the single crystal. When the size of the quartz crucible 1 is determined, according to the size of the quartz crucible 1, the size of the thermal field that can be used in combination with this quartz crucible 1 can be selected. This thermal field satisfies that the distance from the edge of the single crystal 2 to the inner wall of the quartz crucible 1 during the crystal growth process exceeds the preset value, so that the thermal field meets the requirements of the crystal pulling process.

[0058] In some feasible embodiments, the above preset value of the distance is 340 mm, and the distance between the edge of the single crystal 2 and the corresponding inner wall of the quartz crucible 1 is controlled to be greater than 340 mm.

[0059] In order to achieve continuous recharging during the crystal pulling process and maintain the stable growth of single crystal 2 during continuous recharging, it is necessary to control the relative distance between the recharging position and the edge of single crystal 2. The relative position between the recharging position and the edge of single crystal 2 is Figure 1 the distance H2 shown in Figure 1 . The region of the silicon melt corresponding to the distance between the recharging position and the edge of single crystal 2 is the crystal formation region. This crystal formation region contains the stable melt region required for crystal growth. During the recharging process, maintaining the stability of the silicon melt in the crystal formation region can maintain the stability of the Taylor column region, thereby enhancing the crystal growth stability during the crystal pulling process.

[0060] The distance between the recharging position and the inner wall of quartz crucible 1 is Figure 1 the distance H3 shown in Figure 1 . The region of the silicon melt corresponding to the distance between the recharging position and the inner wall of quartz crucible 1 is the feeding region. During continuous recharging, the recharged material continuously enters this feeding region. The recharged material impacts the silicon melt in the feeding region. During the crystal growth process, if most or all of the impact of the recharged material on the silicon melt is maintained in the feeding region, then it is possible to reduce the impact of the recharged material on the silicon melt in the crystal formation region, and further reduce the impact of the recharged material on the silicon melt in the Taylor column region, enhancing the crystal growth stability during the crystal pulling process.

[0061] According to the positional relationship between single crystal 2 and quartz crucible 1, it can be known that the distance between the edge of single crystal 2 and the corresponding inner wall of quartz crucible 1 includes the crystal formation region distance and the feeding region distance arranged in sequence along the direction from the edge of single crystal 2 to the inner wall of quartz crucible 1. That is, the sum of the distance from the edge of single crystal 2 to the recharging position and the distance from the recharging position to the inner wall of quartz crucible 1 is the distance from the edge of single crystal 2 to the corresponding inner wall of quartz crucible 1. Controlling the distance from the edge of single crystal 2 to the corresponding inner wall of quartz crucible 1 can be achieved by controlling the distance between the edge of single crystal 2 and the recharging position. That is, controlling the crystal formation region distance, and controlling the crystal formation region distance to be greater than the first distance preset value, where the first distance preset value is less than the distance preset value.

[0062] In some feasible embodiments, the first distance preset value is 270 mm.

[0063] When the size of the quartz crucible 1 is determined, the size of the heat field can be determined. The size of the heat field is not less than 36 inches, that is, the size of the heat field can be 36 inches and above, such as: 46-inch heat field, 48-inch heat field, etc., which is selected according to the size of the quartz crucible 1. After the size of the quartz crucible 1 and the heat field are determined, the material is loaded and the single crystal 2 is pulled. The processes of material chemistry, temperature stabilization, crystal seeding, shoulder expansion, shoulder rotation, and equal diameter are carried out in sequence. During the pulling process of the single crystal 2, when entering the equal diameter process, continuous re-feeding is carried out, so that during the equal diameter process, the re-feeding continues to enter the quartz crucible 1 and the re-feeding continues to enter the feeding area. When the equal diameter process is completed, the continuous re-feeding is stopped, and there is no need to do a lot of complicated and ineffective work to prepare for the production of a new single crystal 2 after completing the production of a single crystal 2.

[0064] In the equal diameter stage, in conjunction with continuous re-throwing, the rotation speeds of the quartz crucible 1 and the single crystal 2 are controlled so that the rotation speeds of the quartz crucible 1 and the single crystal 2 are matched to increase the stability of the Taylor column region and improve the survival rate of continuous re-throwing and continuous crystal growth.

[0065] In some feasible embodiments, the rotation speed of the quartz crucible 1 is greater than 4 rpm. The rotation speed of the quartz crucible 1 is selected according to actual needs and no specific requirements are made here.

[0066] In some feasible embodiments, the rotation speed of the single crystal 2 is less than 16 rpm. The rotation speed of the single crystal 2 is selected according to actual needs and no specific requirements are made here.

[0067] To further optimize the solution, in the equal diameter stage, in conjunction with continuous re-investment, the protective gas flow rate and the single crystal furnace pressure can also be controlled. By controlling the protective gas flow rate, volatile impurities can be taken away, and the single crystal furnace pressure can be controlled at the same time. In combination with the rotation speed of the quartz crucible 1 and the rotation speed of the single crystal 2, the stability of the Taylor column area can be increased, and the survival rate of continuous re-investment and continuous crystal growth can be improved to control the stable growth of the single crystal.

[0068] In some feasible embodiments, the protective gas is an inert gas, which may be argon, which will not introduce new impurities and protect the quality of the single crystal 2. The flow rate of the protective gas is greater than 40slpm. The flow rate of the protective gas is selected according to actual needs and no specific requirements are made here.

[0069] In some feasible embodiments, the furnace pressure of the single crystal furnace is less than 30 torr. The furnace pressure of the single crystal furnace is selected according to actual needs and no specific requirements are made here.

[0070] When continuous reinvestment is carried out in the equal-diameter stage, it can be carried out in the entire equal-diameter stage, or it can be carried out in stages. The starting timing of continuous reinvestment is selected according to actual needs.

[0071] Specifically, it can be as follows: continuous recharging is carried out during the isodiameter stage, which can ensure that the liquid level of the silicon solution in the quartz crucible 1 remains unchanged and ensure the smooth progress of single crystal growth. Therefore, during the isodiameter stage, the lifting of the quartz crucible 1 can be not carried out, and the position of the quartz crucible 1 can be kept unchanged.

[0072] When the position of the quartz crucible 1 remains unchanged, the starting time of continuous recharging can be: continuous recharging is carried out starting from the initial stage of the isodiameter stage, that is, from the start to the end of the isodiameter stage, continuous recharging is carried out throughout the isodiameter stage, and during the continuous recharging process, the liquid port distance is controlled to be unchanged. The liquid port distance is the height from the lower edge of the deflector tube to the liquid level of the silicon melt, that is, during the continuous recharging process, the height from the lower edge of the deflector tube to the liquid level of the silicon melt remains unchanged. The liquid port distance is 10 - 50 mm, and the size of the liquid port distance is selected and set according to actual requirements.

[0073] Doping is carried out synchronously during the continuous recharging process. The dopant is mixed with the recharged material. During the continuous recharging process, the dopant enters the silicon melt along with the recharged material for dopant doping. During the isodiameter stage, as the crystal growth progresses, the silicon melt in the quartz crucible 1 will gradually decrease. Therefore, during the crystal growth process, continuous recharging is carried out. During the continuous recharging process, the distance from the liquid level of the silicon melt to the upper edge of the quartz crucible is controlled to be unchanged, that is, during the crystal growth process, the amount of the silicon melt in the quartz crucible 1 is continuously supplemented at all times to keep the position of the liquid level of the silicon melt unchanged to ensure the smooth progress of crystal growth. And with the doping of the dopant, the concentration of the dopant in the silicon melt is controlled so that the doping amount of the dopant in the silicon melt meets the segregation law required for single crystal production, ensuring that the resistivity of the single crystal is within the range required for production and ensuring the quality of the single crystal.

[0074] Or, when the position of the quartz crucible 1 remains unchanged, the starting time of continuous recharging can also be: during the isodiameter stage, continuous recharging is started when the single crystal length is greater than the first length. During the continuous recharging process, the liquid port distance is controlled to be unchanged. The first length is 50 mm, that is, during the isodiameter stage, when the length of the single crystal is greater than 50 mm, continuous recharging is started, and during the continuous recharging process, the liquid port distance is controlled to be unchanged. The liquid port distance is 10 - 50 mm, and the size of the liquid port distance is selected according to actual requirements.

[0075] During continuous recharging, doping is carried out synchronously. The dopant is mixed with the recharged material. During continuous recharging, the dopant enters the silicon melt with the recharged material for dopant doping. In the isodiameter stage, as crystal growth progresses, the silicon melt in the quartz crucible 1 gradually decreases. Therefore, during crystal growth, when the single crystal grows to the first length, continuous recharging is carried out. During continuous recharging, the distance from the liquid surface of the silicon melt to the upper edge of the quartz crucible is controlled to be constant, that is, the position of the liquid surface of the silicon melt is kept unchanged to ensure the smooth progress of crystal growth. And with the doping of the dopant, the concentration of the dopant in the silicon melt is controlled so that the doping amount of the dopant in the silicon melt meets the segregation law required for single crystal production, ensuring that the resistivity of the single crystal is within the production requirements and ensuring the quality of the single crystal.

[0076] Or, it can be: continuous recharging is carried out in the isodiameter stage, and the lifting of the quartz crucible 1 is carried out during continuous recharging. Specifically, in the isodiameter stage, when the single crystal length is greater than the first length, continuous recharging starts, and during continuous recharging, the liquid orifice distance is controlled to be constant. The first length is 50 mm, that is, in the isodiameter stage, when the length of the single crystal is greater than 50 mm, continuous recharging starts, and during continuous recharging, the liquid orifice distance is controlled to be constant. The liquid orifice distance is 10 - 50 mm, and the size of the liquid orifice distance is selected according to actual needs.

[0077] During continuous recharging, doping of the dopant is not carried out. At the same time, the quartz crucible is controlled to rise to control the concentration of the dopant in the silicon melt so that the doping amount of the dopant in the silicon melt meets the segregation law required for single crystal production, ensuring that the resistivity of the single crystal is within the production requirements and ensuring the quality of the single crystal.

[0078] When carrying out continuous recharging, a continuous recharging device 3 is used for recharging. The continuous recharging device 3 is arranged outside the single crystal furnace and is used to continuously supply the recharged material into the quartz crucible 1 to achieve continuous recharging of the recharged material. In order to reduce the splashing of the silicon melt caused by the falling of the recharged material and the influence on the melt stability of the silicon melt, it is necessary to control the particle size of the recharged material and select recharged material with a smaller particle size.

[0079] In some embodiments of the embodiments, the particle size of the recharged material is less than 10 mm. The particle size of the recharged material is selected according to actual needs and no specific requirements are made here.

[0080] The above-mentioned continuous recharging device 3 is prior art and will not be elaborated here.

[0081] A continuous crystal growth system is used when implementing the above-mentioned continuous crystal growth method, such as Figure 1-7As shown, it includes a single crystal furnace device and a continuous refeeding device 3 arranged outside the single crystal furnace device. The continuous refeeding device 3 is connected to the single crystal furnace device so that the refeeding material in the continuous refeeding device 3 can enter the single crystal furnace device. And under the action of the continuous refeeding device 3, the refeeding material can continuously enter the quartz crucible 1 for continuous refeeding of the refeeding material.

[0082] The above-mentioned single crystal furnace device includes a quartz crucible 1, and the quartz crucible 1 is arranged such that the distance between the edge of the single crystal 2 to be drawn and the inner wall of the quartz crucible 1 is greater than a preset distance value. That is, the size of the quartz crucible 1 is selected according to the size of the single crystal 2 to be drawn. When selecting the quartz crucible 1, it is controlled that the distance between the edge of the single crystal 2 and the corresponding inner wall of the quartz crucible 1 is greater than the preset distance value. In some feasible embodiments, the preset distance value is 340 mm.

[0083] For a further optimized solution, as Figure 2-4 shown, in some feasible embodiments, in order to further reduce the impact of the refeeding material on the Taylor column region and enhance the stability of crystal growth during the crystal pulling process, the single crystal furnace device includes a partition component 4, and the partition component 4 is provided with a partition part 401 extending into the silicon melt. The partition part 401 is located between the single crystal 2 and the inner wall of the quartz crucible 1 so that the silicon melt is separated into a crystal growth area and a feeding area. The setting of the partition component 4 can effectively isolate the crystal growth area and the feeding area, and reduce the melt fluctuation caused after the refeeding material drops to the liquid surface of the silicon melt during the continuous refeeding process.

[0084] Therefore, it is necessary to control the distance between the partition part 401 and the inner wall of the quartz crucible 1 so that the area between the partition part 401 and the inner wall of the quartz crucible 1 is the feeding area. The distance between the partition part 401 and the edge of the single crystal 2 is greater than a first preset distance value, and the first preset distance value is 270 mm.

[0085] When installing the partition component 4, it can be arranged on the quartz crucible 1, or the partition component 4 is arranged inside the quartz crucible 1, or the partition component 4 is connected to the deflector cylinder, and it is selected according to the structure of the partition component 4.

[0086] When the partition component 4 is arranged inside the quartz crucible 1, the partition part 401 is a ring structure with a certain length. The partition part 401 is arranged along the axial direction of the quartz crucible 1. The partition part 401 can be inserted into the inside of the quartz crucible 1. In this structure, the partition part 401 can be provided with a plurality of through holes for the flow of the silicon melt on both sides of the partition part 401. The length of the partition part 401 is selected and set according to actual needs; or, the partition part 401 is arranged inside the quartz crucible 1, and the length of the partition part 401 is less than the depth of the quartz crucible 1, and the partition part 401 floats in the silicon melt.

[0087] When the separation component 4 is connected to the flow guide cylinder, the separation component 4 is coaxially arranged with the flow guide cylinder. Specifically, the separation part 401 is connected to the lower end of the flow guide cylinder (the end of the flow guide cylinder facing the silicon melt). In this structure, the end of the separation part 401 located in the silicon melt does not contact the quartz crucible 1, realizing the flow between the silicon melts on both sides of the separation part 401. When the separation part 401 is connected to the lower end of the flow guide cylinder, it can be connected by threads. An annular connecting piece is formed on the outer side of the lower end of the flow guide cylinder along the axial direction of the flow guide cylinder. The annular connecting piece is provided with an external thread, and the end of the separation part 401 connected to the flow guide cylinder is provided with an internal thread, so that the separation part 401 and the flow guide cylinder can be connected by threads; the separation part 401 and the lower end of the flow guide cylinder can also be connected by insertion. When connected by insertion, a slot is provided at the lower end of the flow guide cylinder, and the end of the separation part 401 connected to the flow guide cylinder is provided with a jack. The position of the jack on the separation part 401 corresponds to the position of the slot on the flow guide cylinder. Through the insertion piece, the insertion piece passes through the jack on the separation part 401 and inserts into the slot on the flow guide cylinder to realize the insertion connection between the separation part 401 and the flow guide cylinder.

[0088] When the separation component 4 is arranged on the quartz crucible 1, the separation component 4 is sleeved on the upper end of the quartz crucible 1, and the separation component 4 is of an annular structure to avoid interference with the growth of the single crystal 2 during the crystal pulling process. The separation component 4 includes a connected support part 400 and a separation part 401. The support part 400 is of a groove structure, having a set of side walls arranged oppositely and a bottom wall connected to the set of side walls. The set of side walls is arranged on the same side of the bottom wall, and two of the set of side walls are arranged at both sides of the bottom wall, constructing a support part 400 structure in an inverted U shape. The shape of the support part 400 is adapted to the shape of the top end of the quartz crucible 1, which is circular. The distance between the two side walls is greater than the distance of the feeding area, the sum of the wall thickness of the quartz crucible 1 and the wall thickness of the carbon-carbon crucible, so that the support part 400 is buckled on the top end of the quartz crucible 1, and the outer wall of the carbon-carbon crucible contacts one side wall of the support part 400, and the other side wall is located inside the quartz crucible 1 and above the silicon melt. The bottom wall part between this side wall and the inner wall of the quartz crucible 1 corresponds to the feeding area of the silicon melt. The setting of the support part 400 enables the separation component 4 to be installed on the top end of the quartz crucible 1. The connection relationship between the two side walls and the bottom wall of the support part 400 is a fixed connection, and this fixed connection method is preferably integrally formed.

[0089] In order to enable the re-charged material to accurately and smoothly enter the silicon melt in the charging area, the support portion 400 is provided with a charging hole 402. The charging hole 402 corresponds to the charging area of the silicon melt, so that the re-charged material enters the charging area of the silicon melt through the charging hole 402 during re-charging. The charging hole 402 is located on the bottom wall of the support portion 400, and the charging hole 402 has a certain length. In order to realize the connection between the two side walls of the support portion 400, a plurality of charging holes 402 are provided on the bottom wall, and the plurality of charging holes 402 are arranged in sequence along the circumferential direction of the support portion 400, so that during the crystal pulling process, when the quartz crucible 1 rotates, the re-charged material can enter the charging area of the silicon melt through the charging holes 402. The setting of the charging holes 402 can realize the entry of the re-charged material and the volatilization of the oxygen content in the melt surface.

[0090] In some feasible embodiments, preferably, the number of the charging holes 402 is two.

[0091] The partition portion 401 is a ring structure with a certain length, and the partition portion 401 is arranged along the axial direction of the quartz crucible 1. One end of the partition portion 401 is connected to the side wall of the support portion 400 corresponding to the silicon melt, and the other end of the partition portion 401 extends into the silicon melt along the axial direction of the quartz crucible 1 to partition the silicon melt, realizing an effective partition between the crystal formation area and the charging area of the silicon melt. In this structure, the end of the partition portion 401 located in the silicon melt does not contact the quartz crucible 1, realizing the flow between the silicon melts on both sides of the partition portion 401. The connection relationship between the partition portion 401 and the support portion 400 is a fixed connection, and the fixed connection is preferably integrally formed.

[0092] Further optimized solution, as Figure 5-7 shown, in the existing crystal pulling process, the quartz crucible 1 moves upward during the equal diameter process, and the same position of the quartz crucible 1 will not be continuously baked in the heating area. However, in the continuous crystal pulling and continuous re-charging crystal pulling process, the position of the quartz crucible 1 can be fixed. Therefore, the separation assembly 4 is provided with a shielding portion 403. The shielding portion 403 is located outside the carbon-carbon crucible. The shielding portion 403 is arranged along the axial direction of the quartz crucible 1, that is, one end of the shielding portion 403 is connected to a side wall of the support portion 400 located outside the carbon-carbon crucible, and the other end of the shielding portion 403 extends along the axial direction of the quartz crucible 1 towards the bottom of the quartz crucible 1. And the shielding portion 403 is a ring structure with a certain length, effectively blocking the impact of the heater on the quartz crucible 1, reducing the generation of oxygen content and increasing the single service life of the quartz crucible 1.

[0093] The materials of the above-mentioned support portion 400, partition portion 401 and shielding portion 403 are all quartz, which will not introduce new impurities during the crystal pulling process and will not affect the quality of the single crystal 2.

[0094] When the continuous crystal growth system is in use, according to the size of the single crystal 2 to be drawn and the minimum distance between the edge of the single crystal 2 and the inner wall of the quartz crucible 1, a quartz crucible 1 with a corresponding size is selected, so that the distance between the edge of the single crystal 2 and the inner wall of the quartz crucible 1 is greater than the preset value; after the selection of the quartz crucible 1 is completed, the size of the thermal field corresponding to the quartz crucible 1 is selected to determine the thermal field to be used. After the thermal field size is determined, the quartz crucible 1 is charged, and the charged quartz crucible 1 is installed in the single crystal furnace, and then the separation component 4 is installed at the top of the quartz crucible 1.

[0095] Crystal pulling is carried out. In the isodiameter stage, the position of the quartz crucible 1 is controlled to remain unchanged, and the continuous feeding device 3 operates. The re-fed material enters the quartz crucible 1 through the feeding hole 402 on the separation component 4 and enters the feeding area of the silicon melt for continuous re-feeding. At the same time, the rotation speed of the quartz crucible 1, the rotation speed of the single crystal 2, the flow rate of the protective gas, and the furnace pressure of the single crystal furnace are controlled for crystal growth.

[0096] After the isodiameter stage ends, the feeding of the re-fed material is stopped, and the finishing is carried out to complete the pulling of a single crystal for one time.

[0097] Then, the pulling of the second single crystal is carried out. The procedures such as temperature stabilization and crystal seeding are carried out in sequence for crystal pulling. In the isodiameter stage, the continuous feeding device 3 operates for continuous re-feeding of the re-fed material. After the isodiameter stage ends, the re-feeding of the re-fed material is stopped, and the finishing is carried out; the above steps are repeated, and then the pulling of the next single crystal is carried out.

[0098] Embodiment 2

[0099] Compared with Embodiment 2, in the structure of the continuous crystal growth system of this embodiment, there is no separation component 4, but there is a diversion component 5. Specifically, as Figure 8-9 shown, the single crystal furnace device includes a diversion component 5. The diversion component 5 is arranged at the discharge end of the continuous feeding device 3 and is arranged along the axial direction of the quartz crucible 1. The diversion component 5 corresponds to the discharge port of the continuous feeding device 3 to guide the re-fed material entering the quartz crucible 1 and prevent the re-fed material from splashing out to the crystal growth area during the re-feeding process and damaging the stability during the crystal growth process.

[0100] The above-mentioned diversion component 5 includes a diversion pipe. The diversion pipe is a pipe structure with a certain length. The diversion pipe is arranged along the axial direction of the quartz crucible 1. One end of the diversion pipe is connected to the discharge end 502 of the continuous feeding device 3, and the other end is close to or extends below the liquid level of the silicon melt, so that the re-fed material flowing out of the continuous feeding device 3 directly enters the diversion pipe and flows along the diversion pipe and directly enters the silicon melt after flowing out of the diversion pipe.

[0101] The above-mentioned diversion tube includes a tube main body 500, and a feed end 501 and a discharge end 502 provided at both ends of the tube main body 500. The feed end 501 has a variable diameter structure. The diameter of the end of the feed end 501 connected to the tube main body 500 is smaller than that of the other end. Along the axial direction of the tube main body 500, from the end of the feed end 501 connected to the tube main body 500 to the other end, the diameter gradually increases, so that the shape of the feed end 501 is trumpet-shaped, enabling the feed end 501 to effectively receive the repeatedly fed materials output by the continuous repeated feeding device 3.

[0102] The feed end 501 is detachably connected to the end of the discharge pipe of the continuous repeated feeding device 3. This detachable method can be plug-in connection. For example, a first plug-in member is provided on the outer side wall of the feed end 501, and a second plug-in member is provided at the corresponding position on the outer side wall of the discharge pipe of the continuous repeated feeding device 3. The second plug-in member is provided with a plug-in hole, so that the first plug-in member can be inserted into the plug-in hole to realize the plug-in connection between the feed end 501 and the discharge pipe of the continuous repeated feeding device 3; or, this detachable connection method can be a sleeve connection. For example, a collar is provided on the feed end 501, and the collar is sleeved on the discharge pipe of the continuous repeated feeding device 3; or it can be other detachable connection methods, which are selected according to actual needs.

[0103] The discharge end 502 of the diversion tube has an inclined mouth structure, that is, along the radial direction of the quartz crucible 1, the side surface of the discharge end 502 close to the single crystal 2 is a straight-line structure, and this side surface is arranged parallel to the axis of the quartz crucible 1 of the single crystal 2. The side surface of the discharge end 502 close to the inner wall of the quartz crucible 1 is an inclined-line structure, and this side surface intersects with the axis of the quartz crucible 1, so that the projected shape of the discharge end 502 in the vertical plane is triangular.

[0104] In order to enable the repeatedly fed materials to enter the melt when approaching the liquid surface position, the inclination angle of this inclined mouth structure is not greater than 45°, that is, the included angle between the side surface of the discharge end 502 close to the single crystal 2 and the side surface of the discharge end 502 close to the inner wall of the quartz crucible 1 is not greater than 45°. The size of this included angle is selected according to actual needs and no specific requirements are made here. The setting of the inclined mouth structure can prevent the problem of material jamming during the descent of the raw materials, and also prevent the repeatedly fed materials from splashing into the crystal growth area during the process of entering the silicon melt, maintaining the stability of the melt during the crystal growth process.

[0105] When the continuous crystal growth system is in use, according to the size of the single crystal 2 to be drawn and the minimum distance between the edge of the single crystal 2 and the inner wall of the quartz crucible 1, a quartz crucible 1 with a corresponding size is selected, so that the distance between the edge of the single crystal 2 and the inner wall of the quartz crucible 1 is greater than the preset value; after the quartz crucible 1 is selected, the size of the thermal field corresponding to the quartz crucible 1 is selected to determine the thermal field to be used. After the thermal field size is determined, the quartz crucible 1 is charged, and the charged quartz crucible 1 is installed in the single crystal furnace. Then, the diversion assembly 5 is installed at the end of the discharge pipe of the continuous multi-charge device 3, so that the diversion assembly 5 corresponds to the discharge end of the discharge pipe of the continuous multi-charge device 3.

[0106] Crystal pulling is carried out. In the isodiametric stage, the position of the quartz crucible 1 is controlled to remain unchanged, and the continuous multi-charge device 3 operates. The multi-charge material enters the quartz crucible 1 through the feed end 501, the pipe body 500 and the discharge end 502 of the diversion assembly 5 and the feed hole 402, enters the feeding area of the silicon melt, and continuous multi-charging is carried out. At the same time, the rotation speed of the quartz crucible 1, the rotation speed of the single crystal 2, the flow rate of the protective gas and the furnace pressure of the single crystal furnace are controlled to grow crystals.

[0107] After the isodiametric stage ends, the feeding of the multi-charge material is stopped, and the finishing work is carried out to complete the pulling of a single crystal for one time.

[0108] Then, the pulling of the second single crystal is carried out. The processes such as temperature stabilization and seed crystal introduction are carried out in sequence to carry out crystal pulling. In the isodiametric stage, the continuous multi-charge device 3 operates to carry out continuous multi-charging of the multi-charge material. After the isodiametric stage ends, the recharging of the multi-charge material is stopped, and the finishing work is carried out; the above steps are repeated, and then the pulling of the next single crystal is carried out.

[0109] When the pulling of multiple single crystals is completed and the furnace is disassembled, the diversion assembly 5 is disassembled.

[0110] Due to the adoption of the above technical solution, before crystal pulling, a quartz crucible with a corresponding size is selected according to the size of the single crystal to be pulled, and the distance between the edge of the single crystal and the inner wall of the quartz crucible is controlled to be greater than a preset value. During the crystal pulling process, in the isodiameter stage, continuous recharging is carried out, and the position of the quartz crucible is controlled to remain unchanged. At the same time, the rotation speed of the quartz crucible and the rotation speed of the single crystal are controlled so that during continuous recharging, the recharged material falls into the feeding area of the silicon melt in the quartz crucible, reducing the impact on the Taylor column area during the recharging process, maintaining the stable melt area required for crystal growth, enhancing the stability of crystal growth during crystal pulling, which can not only solve the resistivity attenuation, improve the resistivity concentration, increase the proportion of the high-efficiency resistivity range, improve the battery end efficiency, but also achieve continuous crystal growth, thereby improving the effective crystal growth working hours and increasing the output; adopting this continuous crystal growth method can effectively improve the quality of single crystals, improve the resistivity consistency, increase the proportion of the optimal resistivity range, and improve the product efficiency; it can effectively solve the damage to the stability of the crystal growth area during the continuous recharging process, improve the crystal growth survival rate, and realize the feasibility of the continuous recharging technology; it can effectively reduce the non-effective crystal growth time such as recharging, slow cooling, section taking, temperature stabilization, seed introduction, and shoulder expansion, and increase the output; it can effectively improve the oxygen content of single crystals. A larger crucible diameter ratio promotes the volatilization of oxygen content, reduces the oxygen content of the crystal. At the same time, the melt height remains unchanged, which helps to solve the problem of the increase in the oxygen content at the tail of the crystal rod and the poor crystal formation at the tail; a separation component is provided, which can effectively separate the crystal formation area and the feeding area of the silicon melt, reducing the melt fluctuation caused by the recharged material falling to the liquid surface during the continuous recharging process. The separation component is provided with a feeding hole, which can realize the entry of the recharged material and the volatilization of the oxygen content on the melt liquid surface; a diversion component is provided to receive the recharged material output by the continuous recharging device, so that the recharged material moves along the diversion component, preventing the recharged material from splashing outside the crystal formation area range during feeding and damaging the stability during the crystal growth process.

[0111] The above has described the embodiments of the present invention in detail, but the content described is only the preferred embodiments of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. A method for continuous crystal growth, characterized in that: Including, According to the size of the single crystal to be pulled, select a corresponding quartz crucible, and control the distance between the edge of the single crystal and the inner wall of the quartz crucible to be greater than a preset distance value; Perform crystal pulling. In the equal-diameter stage, perform continuous recharging, and control the rotation speed of the quartz crucible, the rotation speed of the single crystal, and the position of the quartz crucible to control the stable growth of the single crystal.

2. The method for continuous crystal growth according to claim 1, characterized in that: The preset distance value is 340 mm.

3. The method for continuous crystal growth according to claim 1, wherein: The distance between the edge of the single crystal and the quartz crucible includes a crystal formation area distance and a feeding area distance arranged in sequence along the direction from the edge of the single crystal to the inner wall of the quartz crucible, and control the crystal formation area distance to be greater than a first preset distance value.

4. The method for continuous crystal growth according to claim 3, characterized in that: The first preset distance value is 270 mm.

5. The method for continuous crystal growth according to any one of claims 1-4, characterized in that: During the continuous recharging process, control the position of the quartz crucible to remain unchanged.

6. The method for continuous crystal growth according to claim 5, wherein: Start continuous recharging from the beginning of the equal-diameter stage. During the continuous recharging process, control the liquid level distance to remain unchanged, and the liquid level distance is 10 - 50 mm.

7. The method for continuous crystal growth according to claim 5, characterized in that: In the equal-diameter stage, start continuous recharging when the length of the single crystal is greater than a first length. During the continuous recharging process, control the liquid level distance to remain unchanged. The first length is 50 mm, and the liquid level distance is 10 - 50 mm.

8. The method for continuous crystal growth according to claim 6 or 7, characterized in that: During the continuous recharging process, doping is carried out synchronously, and control the distance between the liquid surface of the silicon melt and the upper edge of the quartz crucible to remain unchanged, so that the doping amount of the dopant in the silicon melt satisfies the segregation law required for single crystal production.

9. The method for continuous crystal growth according to any one of claims 1-4, characterized in that: In the equal-diameter stage, start continuous recharging when the length of the single crystal is greater than a first length, control the liquid level distance to remain unchanged, and control the quartz crucible to rise, so that the doping amount of the dopant in the silicon melt satisfies the segregation law required for single crystal production.

10. The method for continuous crystal growth according to claim 9, characterized in that: The first length is 50 mm, and the liquid level distance is 10 - 50 mm.

11. The method for continuous crystal growth according to any one of claims 1-4, 6-7 and 10, characterized in that: The rotation speed of the quartz crucible is greater than 4 rpm, and the rotation speed of the single crystal is less than 16 rpm.

12. The method for continuous crystal growth according to any one of claims 1-4, 6-7 and 10, characterized in that: During the continuous recharging process, also control the flow rate of the protective gas and the furnace pressure of the single crystal furnace to control the stable growth of the single crystal.

13. The method for continuous crystal growth according to claim 12, characterized in that: The flow rate of the protective gas is greater than 40 slpm, and the furnace pressure of the single crystal furnace is less than 30 torr.

14. The method for continuous crystal growth according to claim 1, characterized in that: When performing continuous recharging, use a continuous recharging device for recharging, and the particle size of the recharged material is less than 10 mm.

15. A system for continuous crystal growth, characterized in that: Including a single crystal furnace device and a continuous recharging device arranged outside the single crystal furnace device. The continuous recharging device is communicated with the single crystal furnace device, so that the recharged material in the continuous recharging device can enter the single crystal furnace device for continuous recharging of the recharged material; the single crystal furnace device includes a quartz crucible, and the quartz crucible is set to: the distance between the edge of the single crystal to be pulled and the inner wall of the quartz crucible is greater than a preset distance value.

16. The continuous crystal growth system according to claim 15, wherein: The preset distance value is 340 mm.

17. The continuous crystal growth system according to claim 15, wherein: The single crystal furnace device includes a partition component, and the partition component is provided with a partition part extending into the silicon melt. The partition part is located between the single crystal and the inner wall of the quartz crucible, so that the silicon melt is divided into a crystal formation area and a feeding area.

18. The continuous crystal growth system according to claim 17, wherein: The distance between the partition part and the edge of the single crystal is greater than a first preset distance value, and the first preset distance value is 270 mm.

19. The continuous crystal growth system according to claim 17 or 18, characterized in that: The partition component is arranged in the quartz crucible; or, the partition component is detachably connected to the guide cylinder, and the partition component is coaxially arranged with the guide cylinder.

20. The continuous crystal growth system according to claim 17, wherein: The separation component is provided with a feeding hole, and the feeding hole corresponds to the feeding area of the silicon melt so that when re-feeding is carried out, the re-fed material enters the feeding area of the silicon melt through the feeding hole.

21. The continuous crystal growth system according to claim 17 or 18 or 20, characterized in that: The separation component is provided with a shielding part, the shielding part is located outside the carbon-carbon crucible, and the shielding part is arranged along the axial direction of the quartz crucible.

22. The continuous crystal growth system according to claim 15 or 16, characterized in that: The single crystal furnace device includes a flow guiding component arranged in the quartz crucible. The flow guiding component is detachably connected to the continuous re-feeding device, and the flow guiding component is arranged along the axial direction of the quartz crucible. The flow guiding component corresponds to the discharge port of the continuous re-feeding device to guide the re-fed material entering the quartz crucible.

23. The continuous crystal growth system according to claim 22, characterized in that: The flow guiding component includes a flow guiding pipe. The feeding end of the flow guiding pipe is of a variable diameter structure, and the discharging end of the flow guiding pipe is of an inclined port structure.

24. The continuous crystal growth system according to claim 23, characterized in that: The inclination angle of the inclined port structure is not greater than 45°.

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