Single crystal silicon rod production method based on czochralski method

Abstract

The invention relates to the field of monocrystalline silicon preparation, particularly provides a monocrystalline silicon rod production method based on a czochralski method, and aims to solve the problem of how to improve the crystallization rate of monocrystalline silicon. In order to achieve the purpose, the single crystal silicon rod production method based on the czochralski method comprises the step of adjusting the flow / flow velocity of inert gas and the liquid opening distance from the lower edge of a guide cylinder to the liquid level of molten silicon in an equal-diameter growth stage based on the equal-diameter growth length of single crystals. On the basis of the equal-diameter growth length of single crystals, the flow / flow velocity of inert gas and the liquid opening distance from the lower edge of a guide cylinder to the liquid level of molten silicon are adjusted, so that the heat convection phenomenon between the inert gas and the molten silicon is controlled, the longitudinal temperature gradient in the single crystal furnace is further controlled, and sufficient heat dissipation capability in crystal growth is ensured; the heat released when the molten silicon is converted into the solid silicon is taken away in time, so that the necessary supercooling degree is formed on the interface of the molten silicon and the solid silicon, the single crystal has enough growth power to keep normal growth, and the crystal forming rate of the single crystal is improved.

Description

Technical Field

[0001] The invention relates to the technical field of single crystal silicon preparation, and specifically provides a single crystal silicon rod production method based on the Czochralski method. Background Art

[0002] The transition from liquid to solid phase during the pulling process of single crystal silicon rods is a complex and critical physical phenomenon, especially in the Czochralski method. The Czochralski method is widely used to manufacture high-purity single crystal silicon required for semiconductors and solar panels. In this process, single crystal silicon is gradually pulled out from the molten silicon liquid, cooled layer by layer and solidified into solid single crystal silicon. In this process, a large amount of latent heat of crystallization is released along with the phase change from liquid to solid. This latent heat release has a significant effect on the temperature distribution of the melt, resulting in changes in the temperature field. If the temperature field is not uniform, it may cause instability in the temperature gradient, which will reduce the crystallization rate of single crystal silicon.

[0003] Accordingly, the art needs a new method for producing single crystal silicon rods based on the Czochralski method to solve the above problems. Summary of the invention

[0004] The present invention aims to solve the above technical problem, namely, to solve the problem of how to improve the crystallization rate of single crystal silicon.

[0005] In a first aspect, the present invention provides a method for producing single crystal silicon rods based on the Czochralski method, characterized in that the method comprises: in the isodiametric growth stage, based on the isodiametric growth length of the single crystal, adjusting the inert gas flow rate / flow velocity and the liquid inlet distance from the lower edge of the guide tube to the molten silicon liquid surface.

[0006] When adopting the above technical scheme, based on the equal-diameter growth length of the single crystal, the inert gas flow rate / flow velocity and the liquid mouth distance from the lower edge of the guide tube to the molten silicon liquid surface are adjusted to control the thermal convection phenomenon between the inert gas and the molten silicon, and then control the longitudinal temperature gradient in the single crystal furnace, ensure that there is sufficient heat dissipation capacity during crystal growth, and promptly take away the heat released when the molten silicon is converted into solid silicon, so that the interface between the molten silicon and the solid silicon forms the necessary supercooling, so that the single crystal has sufficient growth momentum to maintain normal growth, thereby improving the crystallization rate of the single crystal.

[0007] In the optional technical solution of the above-mentioned single crystal silicon rod production method based on the direct pulling method, it is characterized in that the step of "adjusting the inert gas flow rate / flow velocity and the liquid inlet distance from the lower edge of the guide tube to the molten silicon liquid surface based on the equal-diameter growth length of the single crystal" further includes: when the growth length of the single crystal is less than or equal to the first preset length, the inert gas flow rate / flow velocity and the liquid inlet distance from the lower edge of the guide tube to the molten silicon liquid surface are increased every time the single crystal increases by the second preset length; the second preset length is less than the first preset length.

[0008] When the above technical solution is adopted, in the equal-diameter growth stage, when the growth length of the single crystal is less than or equal to the first preset length, when the equal-diameter growth length of the single crystal becomes longer and longer, the silicon material in the crucible will be reduced. Since there is less silicon material in the crucible but the heating power remains unchanged, the temperature in the furnace will increase. In this case, if only the inert gas flow rate / flow velocity is controlled to increase, the supercooling of the silicon liquid will increase, affecting the growth of the single crystal. If only the liquid mouth distance is controlled to increase, the latent heat of the silicon liquid interface cannot be dissipated in time. Therefore, the present invention increases the liquid mouth distance and the inert gas flow rate / flow velocity at the same time, which can quickly remove the surface temperature, ensure the formation of supercooling, reduce the longitudinal temperature gradient of the single crystal silicon rod, especially reduce the temperature gradient at the interface between the single crystal silicon rod and the molten silicon, and ensure the dislocation-free and stable growth of the single crystal silicon rod.

[0009] In the optional technical solution of the above-mentioned single crystal silicon rod production method based on the direct pulling method, it is characterized in that the step of "adjusting the inert gas flow rate / flow velocity and the liquid inlet distance from the lower edge of the guide tube to the molten silicon liquid surface based on the equal-diameter growth length of the single crystal" further includes: when the single crystal growth length is greater than the first preset length, the inert gas flow rate / flow velocity and the liquid inlet distance remain unchanged.

[0010] When the above technical solution is adopted, in the later stage of equal diameter growth, the growth of the crystal has formed a certain growth law and a stable growth environment. Stable inert gas flow / flow rate and liquid inlet distance help maintain a constant temperature environment and maintain high crystal quality. However, too many changes in process parameters may lead to unstable growth rate, which in turn affects the uniformity and quality of the crystal.

[0011] In the optional technical solution of the above-mentioned single crystal silicon rod production method based on the direct pulling method, it is characterized in that when the single crystal growth length is less than or equal to the first preset length, the ratio of the increase in the inert gas flow rate / flow velocity each time to the increase in the liquid mouth distance is the same.

[0012] In the case of adopting the above technical solution, during the growth of single crystal silicon, the ratio of the increase in the inert gas flow / flow velocity to the increase in the liquid mouth distance is the same each time, which can optimize the fluid dynamics environment in the furnace, making the flow of molten silicon liquid more stable, thereby facilitating uniform heat conduction and cooling, and avoiding temperature fluctuations and crystal growth defects caused by uneven flow. Since changes in temperature gradients can cause thermal stress, if the ratio of the increase in the inert gas flow / flow velocity to the increase in the liquid mouth distance is the same each time, the temperature gradient can be better controlled, reducing the thermal stress caused by temperature changes, thereby reducing stress defects in the crystal.

[0013] In the optional technical solution of the above-mentioned single crystal silicon rod production method based on the Czochralski method, it is characterized in that when the single crystal growth length is less than or equal to the first preset length, the increase in the inert gas flow rate / flow velocity each time is the same.

[0014] In the optional technical solution of the above-mentioned single crystal silicon rod production method based on the Czochralski method, it is characterized in that when the single crystal growth length is less than or equal to the first preset length, the increase value of the liquid mouth distance is the same each time.

[0015] When the above technical solution is adopted, the same increase in inert gas flow / velocity and liquid mouth distance each time can ensure stable control of temperature and supercooling. During the growth of single crystal silicon, slight fluctuations in temperature will affect the quality of the crystal. The present invention, by setting a unified increment value, can ensure that each adjustment can bring the expected effect and avoid temperature instability caused by inconsistent parameter changes. In this way, the longitudinal temperature gradient of the single crystal silicon rod can be effectively controlled, especially the temperature gradient at the interface between the single crystal silicon rod and the molten silicon can be made more uniform, thereby reducing the generation of internal defects and dislocations in the crystal and ensuring the high quality and stable growth of the single crystal silicon rod.

[0016] In the optional technical solution of the above-mentioned single crystal silicon rod production method based on the direct pulling method, it is characterized in that the method also includes: in the final stage, keeping the inert gas flow rate / flow velocity unchanged and increasing the liquid mouth distance; or in the final stage, reducing the inert gas flow rate / flow velocity and keeping the liquid mouth distance unchanged.

[0017] When the above technical solution is adopted, in the final stage, the amount of molten silicon is relatively small. At this time, the inert gas flow rate / flow velocity is kept unchanged and the liquid mouth distance is increased, or the inert gas flow rate / flow velocity is reduced and the liquid mouth distance is kept unchanged. This can slow down the cooling rate and maintain an appropriate degree of supercooling, ensuring that the molten silicon liquid does not solidify quickly, thereby facilitating the uniform growth of the crystal and ensuring normal finishing.

[0018] In the optional technical solution of the above-mentioned single crystal silicon rod production method based on the Czochralski method, it is characterized in that the value range of the first preset length is 2800mm-3000mm; and / or the value range of the second preset length is 400mm-600mm.

[0019] In the case of adopting the above technical solution, by setting a reasonable first preset length and second preset length, the inert gas flow rate can be increased and the liquid nozzle distance can be adjusted at an appropriate time point to maintain temperature stability. Through experimental data and production experience, it can be determined that within these length ranges, increasing the inert gas flow rate and adjusting the liquid nozzle distance can most effectively control the temperature and quality during the single crystal growth process.

[0020] In the optional technical solution of the above-mentioned single crystal silicon rod production method based on the Czochralski method, it is characterized in that, in the equal-diameter growth stage, the initial value of the inert gas flow rate is in the range of 80slpm-100slpm, or the initial value of the inert gas flow rate is 32dm / min-40dm / min; and / or in the equal-diameter growth stage, the initial value of the liquid mouth distance is in the range of 25mm-30mm; and / or the ratio is in the range of 1.5-6.

[0021] In the case of adopting the above technical solution, by setting the above gas flow range, sufficient gas flow can be provided to effectively remove impurities and heat generated during the growth of the single crystal. This optimized flow range can ensure the purity of the single crystal growth environment and the stability of the temperature, which helps to reduce defects and dislocations inside the crystal, thereby improving the quality of the single crystal silicon rod. The initial value of the liquid mouth distance is in the range of 25mm-30mm, which can ensure that the heat exchange efficiency between the silicon liquid and the single crystal interface is optimal during the growth of the single crystal. The appropriate liquid mouth distance can dissipate heat in time, avoid overheating or overcooling, maintain the temperature uniformity of the silicon liquid, promote the uniform growth of the single crystal, and ensure the dislocation-free growth and high quality of the single crystal. The above ratio (the ratio of the inert gas flow rate to the liquid mouth distance) is in the range of 1.5-6, which can establish a balance between the gas flow rate and the liquid mouth distance. This balance can ensure that when the gas flow rate is increased, the liquid mouth distance can also be adjusted accordingly to avoid overcooling or overheating. A reasonable ratio range helps to optimize the heat exchange process, maintain the stability of the single crystal growth environment, and ensure the efficiency and stability of the growth process.

[0022] In the optional technical solution of the above-mentioned single crystal silicon rod production method based on the Czochralski method, it is characterized in that the value range of the increased inert gas flow rate is 8slpm-12slpm, or the value range of the increased inert gas flow rate is 3dm / min-5dm / min.

[0023] In the case of adopting the above technical solution, a moderate increase in the inert gas flow rate and flow rate helps to accurately control the temperature in the single crystal growth environment. By increasing the appropriate amount of gas flow rate or flow rate at each adjustment, it can be ensured that while maintaining the cooling effect, it will not cause drastic temperature fluctuations. This precise control can effectively avoid single crystal defects caused by overcooling or overheating, and improve the quality and purity of single crystal silicon rods. It helps to keep the growth interface smooth and uniform, reduce the generation of internal stress and defects in the crystal, and help improve the consistency and reliability of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0025] Figure 1It is a partial structural schematic diagram of the single crystal furnace of the present invention.

[0026] Description of reference numerals:

[0027] 1- flow guide tube; 2- crucible; 3- molten silicon interface; 4- surface tension convection. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make adjustments as needed to adapt to specific applications. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention.

[0029] The Czochralski method for preparing crystals is to place the raw polycrystalline silicon block into a quartz crucible, then heat the quartz crucible to melt the polycrystalline silicon in the quartz crucible, then insert the seed crystal into the melt surface for welding, rotate the seed crystal at the same time, and then reverse the crucible. The seed crystal is slowly lifted upward, and the crystal rod is prepared through processes such as seeding, enlargement, shoulder rotation, equal diameter growth, and finishing.

[0030] In the isodiameter growth stage, as the single crystal silicon gradually grows, there will be a transition from liquid phase to solid phase. When this transition occurs, latent heat of crystallization will be released, and as the single crystal silicon continues to grow, the liquid level of polycrystalline silicon will also drop. At this time, the distance from the bottom edge of the guide tube to the liquid level of molten silicon (i.e., the liquid mouth distance d) changes. The heat convection generated by the inert gas and molten silicon will cause the liquid surface temperature gradient to fluctuate, which will eventually affect the single crystal to have structural defects or difficult crystallization problems. During the single crystal pulling process, if the distance from the bottom edge of the guide tube to the liquid level of molten silicon is too far or too close, that is, the liquid mouth distance is too large or too small, the longitudinal temperature gradient of the single crystal will be too small or too large. If it is too small, it will not have enough heat dissipation capacity to take away the latent heat generated during crystallization, so that the single crystal cannot grow normally; if it is too large, it is easy to produce dislocations and cause broken edges, thereby affecting the crystallization rate of single crystal silicon.

[0031] Based on the above problems, the present invention provides a method for producing a single crystal silicon rod based on the Czochralski method. The method includes adjusting the inert gas flow rate and the liquid inlet distance based on the equal-diameter growth length of the single crystal during the equal-diameter growth stage. The inert gas can be an inert gas such as argon, helium, neon, xenon, etc. Since the inert gas flow rate and the liquid inlet distance are adjusted according to the equal-diameter length of the single crystal, the thermal convection phenomenon between the inert gas and the molten silicon is controlled, and then the longitudinal temperature gradient in the single crystal furnace is controlled, ensuring sufficient heat dissipation capacity during crystal growth, and timely taking away the heat released when the molten silicon is converted into solid silicon, so that the interface between the molten silicon and the solid silicon forms the necessary supercooling, so that the single crystal has sufficient growth power to maintain normal growth, thereby improving the crystallization rate of the single crystal.

[0032] Specifically, when the growth length of the single crystal is less than or equal to the first preset length, the inert gas flow rate and the liquid port distance are increased each time the single crystal increases by a second preset length, wherein the second preset length is less than the first preset length.

[0033] In the isodiametric growth stage, when the single crystal growth length is less than or equal to the first preset length, when the single crystal isodiametric growth length becomes longer and longer, the silicon material in the crucible will be reduced. Since there is less silicon material in the crucible but the heating power remains unchanged, the temperature in the furnace will increase. In this case, if only the inert gas flow rate is controlled to increase, the supercooling of the silicon liquid will increase, affecting the growth of the single crystal. If only the liquid mouth distance is controlled to increase, the latent heat of the silicon liquid interface cannot be dissipated in time. Therefore, the present invention increases the liquid mouth distance and the inert gas flow rate at the same time, which can quickly remove the surface temperature, ensure the formation of supercooling, reduce the longitudinal temperature gradient of the single crystal silicon rod, and especially reduce the temperature gradient at the interface between the single crystal silicon rod and the molten silicon, thereby ensuring the dislocation-free and stable growth of the single crystal silicon rod.

[0034] Among them, by setting a reasonable first preset length and a second preset length, the inert gas flow rate can be increased and the liquid mouth distance can be adjusted at an appropriate time point to maintain temperature stability. Possibly, the value range of the first preset length is 2800mm-3000mm, and the value range of the second preset length is 400mm-600mm, preferably 500mm. These data can be determined based on actual experiments and a large amount of production experience. Through experimental data and production experience, it can be determined that within these length ranges, increasing the inert gas flow rate and adjusting the liquid mouth distance can most effectively control the temperature and quality during the single crystal growth process.

[0035] Further, when the single crystal growth length is less than or equal to the first preset length, the ratio of the inert gas flow rate increase to the liquid port distance increase is the same each time. For example, when the single crystal isodiameter growth length is in the range of 500mm-1000mm, the inert gas flow rate increase is 10slpm, the liquid port distance increase is 2mm, and the ratio of the two is 5. Then, when the single crystal growth length is in the range of 1000mm-1500mm, the ratio of the inert gas flow rate increase to the liquid port distance increase is still 5, and so on.

[0036] During the growth of single crystal silicon, the ratio of the increase in inert gas flow rate to the increase in liquid mouth distance is the same each time, which can optimize the fluid dynamics environment in the furnace, making the flow of molten silicon liquid more stable, thereby facilitating uniform heat conduction and cooling, and avoiding temperature fluctuations and crystal growth defects caused by uneven flow. Since changes in temperature gradients can cause thermal stress, if the ratio of the increase in inert gas flow rate to the increase in liquid mouth distance is the same each time, the temperature gradient can be better controlled, reducing thermal stress caused by temperature changes, thereby reducing stress defects in the crystal.

[0037] Further, when the single crystal growth length is less than or equal to the first preset length, the increase value of the inert gas flow rate each time is the same, and the increase value of the liquid inlet distance each time is the same.

[0038] The same increase in the inert gas flow rate and the liquid mouth distance each time can ensure the stable control of temperature and supercooling. During the growth of single crystal silicon, slight fluctuations in temperature will affect the quality of the crystal. The present invention can ensure that each adjustment can bring the expected effect by setting a unified increment value, avoiding temperature instability caused by inconsistent parameter changes. In this way, the longitudinal temperature gradient of the single crystal silicon rod can be effectively controlled, especially making the temperature gradient at the interface between the single crystal silicon rod and the molten silicon more uniform, thereby reducing the generation of internal defects and dislocations in the crystal, and ensuring the high quality and stable growth of the single crystal silicon rod.

[0039] As a possible implementation manner, when the growth length of the single crystal is greater than the first preset length, the inert gas flow rate and the liquid inlet distance remain unchanged.

[0040] In the later stage of equal diameter growth, the growth of crystals has formed certain growth rules and a stable growth environment. Stable inert gas flow and liquid inlet distance help maintain a constant temperature environment and maintain high crystal quality. Excessive changes in process parameters may lead to unstable growth rate, which in turn affects the uniformity and quality of the crystal.

[0041] As a possible implementation method, in the final stage, the inert gas flow rate is kept unchanged and the liquid inlet distance is increased.

[0042] In the final stage, the amount of molten silicon is relatively small. At this time, keeping the inert gas flow rate unchanged and increasing the liquid inlet distance can slow down the cooling rate, maintain an appropriate degree of supercooling, and ensure that the molten silicon does not solidify quickly, thereby contributing to the uniform growth of the crystal and ensuring normal finishing.

[0043] As an alternative implementation, in the final stage, the inert gas flow rate can be reduced to keep the liquid mouth distance unchanged. This production method can also slow down the cooling speed, maintain an appropriate degree of supercooling, and ensure that the molten silicon liquid does not solidify quickly, thereby facilitating the uniform growth of the crystal and ensuring normal finalization.

[0044] Possibly, in the isodiameter growth stage, the initial value of the inert gas flow rate is in the range of 80slpm-100slpm, preferably 90slpm. The initial value of the liquid port distance is in the range of 25mm-30mm, preferably 28mm. The ratio of the increase in the inert gas flow rate each time to the increase in the liquid port distance is in the range of 1.5-6, preferably 5. The increase in the inert gas flow rate is in the range of 8slpm-12slpm, preferably 10slpm.

[0045] Preferably, the single crystal growth length is divided into the following five stages: 0mm-500mm, 500mm-1000mm, 1000mm-1500mm, 1500mm-3000mm, and 3000mm-end. The changes in the inert gas flow rate and the liquid mouth distance in each stage are different and the ranges are 90slpm-120slpm and 28mm-36mm, respectively. The changes in the inert gas flow rate and the liquid mouth distance within the above range reduce the thermal convection phenomenon between the inert gas and the molten silicon, that is, reduce the surface tension convection phenomenon (surface tension convection refers to the convection form caused by the difference in surface tension caused by the temperature gradient of the liquid surface), and promptly take away the latent heat of crystallization released when the molten silicon is transformed into solid silicon, so that the interface between the molten silicon and the solid silicon forms the necessary supercooling, ensuring that the single crystal can grow normally, thereby improving the crystallization rate of the single crystal and reducing production costs.

[0046] The parameters of the embodiments of the present invention and the comparative examples, as well as the experimental results of the wire breakage rate (%) and the crystallization rate (%) are compared with the following table. The difference between the present invention and the comparative example is only the adjustment of the inert gas flow rate and the liquid port distance parameters, and the other parameters remain unchanged.

[0047] Embodiment 1:

[0048] Comparative Example 1:

[0049] After the single crystal is pulled using the above process, the detailed crystal pulling data is as follows: Experimental items Wire breakage rate (%) Crystallization rate (%) Comparative Example 1 43 83 Embodiment 1 30 90

[0050] Embodiment 2:

[0051] Comparative Example 2:

[0052] After the single crystal is pulled using the above process, the detailed crystal pulling data is as follows: Experimental items Wire breakage rate (%) Crystallization rate (%) Comparative Example 2 47 79 Embodiment 2 37 85

[0053] Embodiment three:

[0054] Comparative Example 3:

[0055] After the single crystal is pulled using the above process, the detailed crystal pulling data is as follows: Experimental items Wire breakage rate (%) Crystallization rate (%) Comparative Example 3 44 81 Embodiment 3 35 86

[0056] Through experimental comparison, the inert gas flow rate and liquid mouth distance from the lower edge of the guide tube to the molten silicon liquid surface were adjusted according to the change of the single crystal growth length. The breakage rate of the single crystal silicon rod decreased, and the crystallization rate increased significantly. This shows that this process method controls the longitudinal temperature gradient of the single crystal to a value suitable for the normal growth of the single crystal, and promptly takes away the crystallization latent heat released when the molten silicon is transformed into solid silicon, thus solving the problem of difficult crystallization.

[0057] It should be noted that although the present invention is introduced by taking the inert gas flow rate as an example, its specific form is not unique. For example, the inert gas flow rate can be replaced by the inert gas flow rate. These adjustments do not deviate from the principle of the present invention and are within the protection scope of the present invention. When it is the inert gas flow rate, its initial value in the equal diameter growth stage can be 32dm / min-40dm / min. The value range of its increase each time can be 3dm / min-5dm / min, preferably 4dm / min. The value range of the ratio of the increase in the inert gas flow rate each time to the increase in the liquid mouth distance is 1.5-6, preferably 2.

[0058] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A method for producing a single crystal silicon rod based on a Czochralski method, characterized in that: The method comprises: During the isodiametric growth stage, the inert gas flow rate / velocity and the liquid inlet distance from the lower edge of the guide tube to the molten silicon liquid surface are adjusted based on the isodiametric growth length of the single crystal.

2. The method for producing a single crystal silicon rod based on the Czochralski method according to claim 1, characterized in that: The step of "adjusting the inert gas flow rate / flow velocity and the liquid inlet distance from the lower edge of the guide tube to the molten silicon liquid surface based on the single crystal equal diameter growth length" further includes: When the growth length of the single crystal is less than or equal to the first preset length, the inert gas flow rate / flow velocity and the liquid inlet distance from the lower edge of the guide tube to the molten silicon liquid surface are increased every time the single crystal increases the second preset length; The second preset length is smaller than the first preset length.

3. The method for producing a single crystal silicon rod based on the Czochralski method according to claim 2, characterized in that: The step of "adjusting the inert gas flow rate / flow velocity and the liquid inlet distance from the lower edge of the guide tube to the molten silicon liquid surface based on the single crystal equal diameter growth length" further includes: When the single crystal growth length is greater than the first preset length, the inert gas flow rate / flow velocity and the liquid inlet distance remain unchanged.

4. The method for producing a single crystal silicon rod based on the Czochralski method according to claim 2, characterized in that: When the single crystal growth length is less than or equal to the first preset length, the ratio of the increase in the inert gas flow rate / flow velocity each time to the increase in the liquid port distance is the same.

5. The method for producing a single crystal silicon rod based on the Czochralski method according to claim 2, characterized in that: When the single crystal growth length is less than or equal to the first preset length, the increase value of the inert gas flow rate / flow velocity is the same each time.

6. The method for producing a single crystal silicon rod based on the Czochralski method according to claim 2 or 5, characterized in that: When the single crystal growth length is less than or equal to the first preset length, the increase value of the liquid mouth distance is the same each time.

7. The method for producing a single crystal silicon rod based on the Czochralski method according to claim 1, characterized in that: The method further comprises: In the final stage, the inert gas flow rate / flow velocity is kept constant and the liquid port distance is increased; or In the final stage, the inert gas flow rate / flow velocity is reduced to keep the liquid-to-mouth distance unchanged.

8. The method for producing a single crystal silicon rod based on the Czochralski method according to any one of claims 2 to 4, characterized in that: The first preset length has a value range of 2800 mm-3000 mm; and / or The second preset length has a value range of 400 mm-600 mm.

9. The method for producing a single crystal silicon rod based on the Czochralski method according to claim 4, characterized in that: In the isodiameter growth stage, the initial value of the inert gas flow rate is in the range of 80slpm-100slpm, or the initial value of the inert gas flow rate is in the range of 32dm / min-40dm / min; and / or In the isodiameter growth stage, the initial value of the liquid-to-mouth distance is in the range of 25 mm to 30 mm; and / or The ratio ranges from 1.5 to 6.

10. The method for producing a single crystal silicon rod based on the Czochralski method according to claim 9, characterized in that: The value range of the inert gas flow rate increase value is 8slpm-12slpm, or the value range of the inert gas flow rate increase value is 3dm / min-5dm / min.

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