Liquid port distance control method

Abstract

The invention belongs to the technical field of monocrystalline silicon manufacturing, and particularly relates to a liquid port distance control method, which comprises the following steps of: horizontally dividing a quartz crucible into a plurality of areas along the height direction in sequence, obtaining the height Hi and the weight Wi of a solution in each area, setting deformation, and calculating a reference Ratio value by combining with other parameters, calculating the weight M of the grown single crystal according to the average seed crystal growth speed in unit time, and calculating the compensation height H of the quartz crucible when the liquid level rises or falls by combining the height Hi and weight Wi parameters of the corresponding area; the actual position change value CP of the quartz crucible is compared with the compensation height Hi to obtain a difference value Zi, the ascending speed of the quartz crucible is adjusted by combining the ascending speed Fi of the liquid level, so that the actual liquid level change meets the expectation, the stability of the liquid opening distance is ensured, the difference value influence of the previous unit time is considered when crystal growth is not completed, and further optimization and adjustment are performed. Therefore, the continuous changing conditions in the whole crystal growth process can be adapted, and the deviation of the liquid opening distance can be more stably controlled to be below 0.5%.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of single crystal silicon manufacturing, and particularly relates to a liquid port distance control method. BACKGROUND

[0002] In the production and manufacturing process of single crystal silicon, crystal originated particles (COP) are one of the key factors affecting the quality of single crystal silicon. The size, quantity and distribution of COP have a crucial influence on the performance and reliability of semiconductor devices ultimately made of single crystal silicon.

[0003] Research has found that the control of COP is closely related to the V / G value in the crystal growth process. Among them, V represents the growth rate, and G represents the temperature gradient during growth. In the single crystal silicon growth process, the growth rate V can usually be controlled in a certain range or specific value by motor control combined with corresponding control logic. For example, by adjusting the speed and motion parameters of the motor, precise adjustment of the growth rate of single crystal silicon can be realized to meet the growth requirements under different process conditions.

[0004] However, the control of temperature gradient G faces many challenges. Temperature gradient is influenced by many complex factors, even if the growth heat field is fixed, it will change due to changes in factors such as liquid port distance (Gap). The liquid port distance (Gap) refers to the distance from the bottom of the heat shield to the surface of the solution, and the structure, material and heating method of the heat zone will all affect the temperature gradient. The liquid port distance (Gap) plays a crucial role in the control of COP. The size of this value directly determines the cooling speed and cooling time of the single crystal after solidification in different defect growth intervals. Different cooling speeds and cooling times will cause different types of defects to form inside the single crystal, thereby affecting the distribution and characteristics of COP. For example, when the liquid port distance (Gap) is too large, the cooling speed of the single crystal after solidification may be slow, and the cooling time is long, which may cause some defects to be more easily generated and aggregated; on the contrary, when the liquid port distance (Gap) is too small, the fast cooling speed and short cooling time may cause other types of defect problems. Therefore, precise control of the liquid port distance (Gap) is crucial for effective control of COP in single crystal silicon, and is a key link to improve the quality of single crystal silicon.

[0005] At present, the commonly used method for controlling the liquid gap (Gap) in the industry is to use a Gap Sensor instrument. The instrument controls the liquid gap (Gap) by detecting the distance between the bottom of the heat shield and the surface of the solution. However, this method has obvious limitations. The Gap Sensor instrument is highly dependent on the shape of the heat shield and the reflection of the heat shield on the surface of the solution. In actual production, when using an inappropriate heat shield shape for crystal growth, the shape of the heat shield and its reflection on the surface of the solution will change, causing the Gap Sensor instrument to be unable to accurately control the liquid gap (Gap), thereby facing the risk of out-of-control Gap control. SUMMARY

[0006] In view of this, the present application provides a liquid gap control method to solve the limitations of using a Gap Sensor instrument to control the liquid gap in the prior art, i.e., when using an inappropriate heat shield shape for crystal growth, the shape of the heat shield and its reflection on the surface of the solution will change, causing the Gap Sensor instrument to be unable to accurately control the liquid gap, thereby solving the above technical problems.

[0007] To achieve the above purpose, the following solutions are adopted in the present application:

[0008] A liquid gap control method, comprising the following steps:

[0009] S10. Dividing a quartz crucible into several regions along the height direction in sequence, and obtaining the height H of the solution in each region i and the weight W i , wherein i is the number of the corresponding region, i = 0, 1, 2, 3, …, Y;

[0010] Setting the deformation amount of the quartz crucible, and obtaining the reference Ratio value according to the deformation amount of the quartz crucible and the solution diameter b i in each region, and calculating the rising speed F of the liquid surface in the crucible when the liquid surface in the crucible is in the region according to the Ratio value i ;

[0011] S20. Setting a unit time T, and obtaining the average seed crystal growth speed S in the unit time T, calculating the weight M of the single crystal grown in the unit time T according to the unit time T and the average seed crystal growth speed S, and calculating the compensation height AH of the quartz crucible when the liquid surface rises or falls according to the weight M of the single crystal, the height H of the solution in each region i , and the weight W i of the height of the solution in each region;

[0012] S30. Detecting the actual position change value ACp of the quartz crucible in the unit time T;

[0013] S40. Set the initial loop count j = 1, and calculate ΔCP, ΔH, and F within the current unit time T. i Calculate the difference Z j Z j =△CP - △H, store Z j The value is determined by the rising speed F of the liquid level inside the crucible. i Sum and difference Z j The actual lifting speed of the quartz crucible is adjusted using the following formula: C j =F i +Z j +Z j-1 If crystal growth is complete after the unit time ends, the operation ends; otherwise, if crystal growth is not complete after the unit time ends, increment j by one and jump to step S10 to recalculate the rising speed F of the liquid level in the crucible. i Then, perform steps S30-S40.

[0014] Preferably, in step S10, the step of "dividing the quartz crucible into several regions horizontally along the height direction" includes: determining the quartz crucible into region A and region B, where region A is a straight-arm region and the inner diameter of the quartz crucibles in region A is consistent, and region B is a region with an R-angle radius R2, and dividing region B into Y regions, where Y is 15-20.

[0015] Preferably, the method for confirming region B includes: pre-setting region C based on the radius R1 of the bottom of the quartz crucible; region B being the area between region A and region C; confirming region C based on angle α, where angle α is the angle between the centerline and a fixed angle line; and the crucible area corresponding to angle α is region C. The angle α is calculated using the following formula:

[0016] sinα=(D / 2-R2) / (R1-R2), where D is the inner diameter of the quartz crucible.

[0017] Preferably, in step S10, the height H of each region is... i Calculated using the following formula:

[0018] H i =V i / (D / 2)2*π, where V: volume of solution in quartz crucible, D: inner diameter of quartz crucible.

[0019] Preferably, in step S10, the weight W of each region is... i Calculated using the following formula:

[0020] W i =V i *2.533 / 10 6 In the formula, V is the volume of the solution inside the quartz crucible.

[0021] Preferably, in the S10 step, the Ratio value is obtained according to the following formula:

[0022] Ratio = d 2 / b i 2 *(1-e), wherein: d: single crystal diameter, e: deformation amount 6%-8%.

[0023] b i = 2*√(R2 2 -(H B *X / Y) 2 +(D / 2)-R2, wherein X: value range 0-Y, H B : height value of each region after the B region is evenly divided into Y regions.

[0024] Preferably, in the S10 step, the rising speed F i of the liquid surface in the crucible is calculated by the following formula:

[0025] F i = Ratio*Z, wherein Z: seed crystal rising speed.

[0026] Preferably, in the S20 step, the single crystal weight M grown in the unit time T is calculated by the following formula:

[0027] M = T*S*(d / 2) 2 *π*2.329 / 10 -6 , wherein: d: single crystal diameter.

[0028] Preferably, in the S20 step, the compensation height ΔH is calculated by the following formula:

[0029] ΔH = M*(H i / W i ).

[0030] Preferably, in the S20 step, the unit time T is an integer multiple of the instantaneous seed crystal growth speed, and the integer multiple is ≤5.

[0031] In the above liquid level distance control method, the quartz crucible is first divided into a plurality of regions according to the inner diameter characteristics. Through the division of the regions, the influence of each region on the liquid level distance can be more accurately analyzed. Then, by setting the deformation amount and combining other parameters, the reference Ratio value is calculated, which provides a basis for the subsequent calculation of the rising speed F i of the liquid surface in the crucible. The average seed crystal growth speed in the unit time reflects the growth speed of the single crystal. According to this, the grown single crystal weight M is calculated, and then combined with the height H i and weight W iThe parameters are used to calculate the compensation height AH of the quartz crucible when the liquid level rises or falls; the actual position change value ACp of the quartz crucible is compared with the compensation height AH i , to obtain a difference value Z i , and the liquid level rising speed F i in the crucible is combined to adjust the rising speed of the quartz crucible, so that the actual liquid level change meets the expectation and the meniscus distance is stable . When the crystal growth is not completed, the difference value of the previous unit time is considered to further optimize and adjust, that is, the difference value of the previous unit time needs to be increased to adapt to the changing conditions in the entire crystal growth process. Through the method provided in the application, the deviation of the meniscus distance can be more stably controlled below 0.5%, thereby improving the quality and stability of single crystal growth, reducing crystal defects caused by improper control of the meniscus distance, and improving the yield and performance of single crystal products. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The figure is a schematic diagram of the quartz crucible A and B regions in the application.

[0033] Figure 2 The figure is a detection result diagram in the embodiment of the application.

[0034] Figure 3 The figure is a detection result diagram in the comparative example of the application. DETAILED DESCRIPTION

[0035] In order to facilitate the understanding of the application, the application will be described more fully below with reference to the accompanying drawings. And the preferred embodiments of the application are given. However, the application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the application more thorough and comprehensive.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application belongs. The terms used in the specification of the application herein are only for the purpose of describing the specific embodiments and are not intended to limit the application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0037] Please refer to Figure 1 , in a specific embodiment, a meniscus distance control method, comprising the following steps:

[0038] A meniscus distance control method, comprising the following steps:

[0039] S10. The quartz crucible is sequentially divided into several regions along the height direction, and the height H i and weight W of the solution in each region are obtainedi wherein i is the number of the corresponding region, i = 0, 1, 2, 3,... Y;

[0040] Setting the deformation amount of the quartz crucible, according to the deformation amount of the quartz crucible and the solution diameter b i Obtaining the reference Ratio value, according to the Ratio value calculating the rising speed F of the liquid surface in the quartz crucible when the liquid surface is in the region i ;

[0041] S20. Setting a unit time T, and obtaining the average seed crystal growth speed S in the unit time T, according to the unit time T and the average seed crystal growth speed S calculating the weight M of the single crystal grown in the unit time T, according to the weight M of the single crystal, the height H i of the solution in each region and the weight W i of the solution in each region calculating the compensation height AH of the quartz crucible when the liquid surface rises or falls;

[0042] S30. Detecting the actual position change value ACp of the quartz crucible in the unit time T;

[0043] S40. Setting the initial cycle number j = 1, according to the ACp, AH and F i in the current unit time T, calculating the difference value Z j : Z j = ACp-AH, storing the value of Z j , according to the rising speed F i of the liquid surface in the crucible and the difference value Z j adjusting the actual rising speed of the quartz crucible, the specific adjustment formula is: C j = F i + Z j + Z j-1 / T, if the single crystal growth is completed after the unit time ends, the work is completed, if the single crystal growth is not completed after the unit time ends, j is added by one, and jumps to step S10 to recalculate the rising speed F i of the liquid surface in the crucible, and executes steps S30-S40.

[0044] For the convenience of understanding, the formula: C j = F i + Z j - Z j-1 / T is specifically explained, for example, in the first unit time, C1 = F1 + Z1-Z0 / T, then in the next unit time, C2 = F2 + Z1 / T, in the next unit time, C3 = F3 + Z2 / T, and so on, and no longer listed.

[0045] Since the physical properties (such as diameter variation) of the solution in different regions of the quartz crucible affect the liquid level change and the single crystal growth, the quartz crucible is divided into different regions according to the inner diameter characteristics in the application, and the influence of each part on the meniscus distance can be more accurately analyzed by subdividing the regions; the quartz crucible deformation, the seed crystal rising speed and the solution diameter of the region are related to each other and jointly affect the liquid level rising speed, according to the quartz crucible deformation, the predetermined seed crystal rising speed and the solution diameter b i of each region, the reference Ratio value is calculated respectively, which provides a basis for the calculation of the subsequent liquid level rising speed F i of the crucible; the average seed crystal growth speed per unit time reflects the growth speed of the single crystal, and the grown single crystal weight M is calculated accordingly, and combined with the solution height H i and weight W i parameters in each region, the compensation height △H of the quartz crucible when the liquid level rises or falls is calculated; by comparing the actual position change value △CP of the quartz crucible with the compensation height △H, the difference value Z i is obtained, Z i =△CP-△H, combined with the liquid level rising speed F i of the crucible, the rising speed of the quartz crucible is adjusted to make the actual liquid level change meet the expectation and ensure the stability of the meniscus distance. When the crystal growth is not completed, the difference value of the previous unit time is considered to further optimize the adjustment, that is, the difference value of the previous unit time needs to be increased to adapt to the changing conditions in the whole crystal growth process. It should be noted that △CP is obtained by detection, for example, it can be detected by a sensor.

[0046] Through the method provided in the application, the deviation of the meniscus distance can be more stably controlled below 0.5%, thereby improving the quality and stability of the single crystal growth, reducing the crystal defects caused by improper control of the meniscus distance, and improving the pass rate and performance of the single crystal product. In addition, the control effect of the method provided in the application is also good in the case of quartz crucible deformation.

[0047] It should be noted that the quartz crucible will deform due to wear, thermal expansion and contraction, etc. after the quartz crucible deforms, it is more difficult to control the meniscus distance of the quartz crucible compared with the standard quartz crucible, that is, after the quartz crucible deforms, the deviation of the meniscus distance is larger when the meniscus distance is controlled by the general method, which is not accurate enough. In order to reflect the effect of the method, a quartz crucible deformation amount is set.

[0048] In one specific embodiment, in step S10, the quartz crucible is divided into several regions along the height direction, including: determining the quartz crucible as an A region and a B region, the A region is a straight arm region, the inner diameter of the quartz crucible in the A region is consistent, the B region is an R angle radius R2 region, the B region is divided into Y regions, Y is 15-20, Y regions can be divided from top to bottom in turn as B1 to B Y Number.

[0049] The confirmation method of the B region includes: according to the quartz crucible bottom radius R1 region, a C region is preset, the B region is between the A region and the C region, the C region is confirmed according to the alpha angle, the alpha angle is the included angle between the center line and the fixed angle line, the crucible region corresponding to the alpha angle is the C region, and the alpha angle is calculated by the following formula:

[0050] sinα=(D / 2-R2) / (R1-R2), wherein D is the inner diameter of the quartz crucible.

[0051] The physical properties of different regions of the quartz crucible, such as the change of the inner diameter, have an important influence on the meniscus distance. The method provided by the application directly confirms the A region and the B region by the solution in the quartz crucible. If the region division is not accurate, it will cause deviation in subsequent calculation and adjustment, and then affect the stability of the meniscus distance. The confirmation method reduces the control error caused by incorrect region division through geometric definition and quantitative calculation, so that the meniscus distance can be controlled in the ideal range, and the stability and consistency of the single crystal growth process are ensured.

[0052] In the S10 step of the above method, the height H of each region is i calculated by the following formula:

[0053] H i =V i / (D / 2)2*π, wherein V is the volume of the solution in the quartz crucible, and D is the inner diameter of the quartz crucible.

[0054] In the S10 step of the above method, the weight W of each region is i calculated by the following formula:

[0055] W i =V i *2.533 / 10 6 , wherein V is the volume of the solution in the quartz crucible.

[0056] In the S10 step of the above method, the Ratio value is obtained according to the following formula:

[0057] Ratio=d 2 / b i2 (1-e), wherein: d: single crystal diameter, e: deformation amount 6%-8%;

[0058] b i = 2*sqrt(R2 2 -(H B *X / Y) 2 +(D / 2)-R2, wherein X: value range 0-Y, H B : height value of each region after B region is evenly divided into Y regions.

[0059] In the above method S10 step, the rising speed F i is calculated by the following formula:

[0060] F i = Ratio*Z, wherein Z: seed crystal rising speed.

[0061] In the above method S20 step, the single crystal weight M grown in unit time T is calculated by the following formula:

[0062] M = T*S*(d / 2) 2 *π*2.329 / 10 -6 , wherein: d: single crystal diameter.

[0063] In the above method S20 step, the compensation height ΔH is calculated by the following formula:

[0064] ΔH = M*(H i / W i ).

[0065] In the above method S20 step, the unit time T is an integer multiple of the instantaneous seed crystal growth speed, and the integer multiple is ≤5.

[0066] The technical solutions and technical effects of the present application are further illustrated by specific experimental examples. It should be noted that the following experimental examples are only for further explaining the present application and do not limit the technical solutions of the present application.

[0067] Embodiment

[0068] The liquid gap is controlled by using the liquid gap control method provided in the present application, including the following steps:

[0069] Step one, determine A region and B region according to the inner diameter of the solution in the quartz crucible, the A region is a straight arm region, the inner diameter of the quartz crucible in the A region is consistent, the B region is an R angle radius R2 region, the B region is evenly divided into Y regions, Y is 20, the Y regions are sequentially numbered from top to bottom as B1 to B 20 Y, and the height H of each region is calculated according to the formulai and weight W i , where i is the number of the corresponding region: i = 0, 1, 2, 3...20, the initial cycle number is set to j = 1, and a unit time T is set; the method for confirming region B in this step includes: confirming region C based on angle α, region C is the region with bottom radius R1, angle α is the angle between the center line and the fixed angle line, the crucible region corresponding to angle α is region C, and the region between region A and region C is region B. The angle α is calculated by the following formula: sinα = (D / 2 - R2) / (R1 - R2), where D is the inner diameter of the quartz crucible;

[0070] Step 2: Set the deformation of the quartz crucible to 6%-8%, based on this deformation, the predetermined seed crystal rising speed, and the solution diameter b in this region. i The reference Ratio values ​​are calculated separately. Based on the real-time value of the seed crystal's rising speed and the Ratio value within that region, the rising speed F of the liquid surface in the quartz crucible when it is in that region is calculated. i ;

[0071] Step 3: Detect the average seed crystal growth rate S within a unit time T. Calculate the weight M of the single crystal grown within that unit time T based on the unit time T and the average seed crystal growth rate S. Calculate the compensation height ΔH of the quartz crucible that needs to be adjusted to accommodate the rise in liquid level based on the single crystal weight M, the height Hi of the corresponding region of the single crystal, and the weight Wi of the corresponding region of the single crystal.

[0072] Step 4: Detect the actual position change ΔCP of the quartz crucible within a unit time T using a sensor;

[0073] Step 5: Based on ΔCP, ΔH, and F within the current unit time T i Calculate the difference Z j Z j =△CP - △H, store Z j The value of C is used to adjust the actual lifting speed of the quartz crucible. The specific adjustment formula is: C j =F i +Z j +Z j-1 / T, and repeat steps two through five 20 times, and use a liquid gate distance tester to measure the liquid gate distance when the single crystal length is 200mm-1700mm. The test results are as follows. Figure 2 As shown.

[0074] Comparative Example

[0075] The liquid gate distance is controlled using this method: An initial gap value is given before crystal pulling, and the accurate gap value is confirmed through position adjustment before crystal pulling. The parameters include a crucible ratio, which is calculated using the crystal rod diameter, crucible diameter, and feed rate. The specific control logic is: Ratio = crucible rising speed / seed crystal rising speed. The crucible rising speed is calculated from the real-time value of the seed crystal rising speed and the Ratio value within this range. The liquid gate distance is controlled by this crucible rising speed. The liquid gate distance is measured using a liquid gate distance tester when the single crystal length is 200mm-1700mm. The test results are as follows: Figure 3 As shown.

[0076] Figure 2 The liquid outlet distance deviation for single crystals ranging from 200mm to 1700mm is less than 0.5% and relatively stable, without abnormal fluctuations; while Figure 3 The liquid nozzle distance deviation for single crystals with a length of 200mm-1700mm is about 4% and fluctuates greatly. Therefore, the liquid nozzle distance control method provided in this application can more stably and accurately control the liquid nozzle distance deviation to below 0.5%.

[0077] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. A method for controlling the distance between liquid outlets, characterized in that, Includes the following steps: S10. Divide the quartz crucible horizontally into several regions along the height direction, and obtain the height H of the solution in each region. i and weight W i , where i is the number of the corresponding region, i = 0, 1, 2, 3...Y; The deformation amount of the quartz crucible is set, based on the deformation amount of the quartz crucible and the solution diameter b in each region. i Obtain the baseline Ratio value, and calculate the rising velocity F of the liquid level in the quartz crucible when the liquid level is in that region based on the Ratio value. i ; S20. Set a unit time T and obtain the average seed crystal growth rate S within the unit time T. Calculate the weight M of the single crystal grown within the unit time T based on the unit time T and the average seed crystal growth rate S. Then, calculate the weight M of the single crystal grown within that unit time T based on the single crystal weight M and the height H of the solution in each region. i and the weight W of the solution height in each region. i Calculate the compensation height ΔH of the quartz crucible when the liquid level rises or falls; S30. Detect the actual position change value △CP of the quartz crucible within the unit time T; S40. Set the initial loop count j = 1, and calculate ΔCP, ΔH, and F within the current unit time T. i Calculate the difference Z j Z j =△CP - △H, store Z j The value is determined by the rising speed F of the liquid level inside the crucible. i Sum and difference Z j The actual lifting speed of the quartz crucible is adjusted using the following formula: C j =F i +Z j +Z j-1 If crystal growth is complete after the unit time ends, the operation ends; otherwise, if crystal growth is not complete after the unit time ends, increment j by one and jump to step S10 to recalculate the rising speed F of the liquid level in the crucible. i Then, perform steps S30-S40.

2. The liquid outlet distance control method according to claim 1, characterized in that, In step S10, "dividing the quartz crucible into several regions horizontally along the height direction" includes: determining the quartz crucible as region A and region B, where region A is a straight-arm region and the inner diameter of the quartz crucibles in region A is consistent, and region B is a region with an R-angle radius R2, and dividing region B into Y regions, where Y is 15-20.

3. The liquid outlet distance control method according to claim 2, characterized in that, The method for confirming region B includes: pre-setting region C based on the radius R1 of the bottom of the quartz crucible; region B being the area between region A and region C; confirming region C based on angle α, where angle α is the angle between the centerline and a fixed angle line; the crucible area corresponding to angle α is region C; and angle α is calculated using the following formula: sinα=(D / 2-R2) / (R1-R2), where D is the inner diameter of the quartz crucible.

4. The liquid outlet distance control method according to claim 1, characterized in that, In step S10, the height H of each region i Calculated using the following formula: H i =V i / (D / 2)2*π, where V: volume of solution in quartz crucible, D: inner diameter of quartz crucible.

5. The liquid outlet distance control method according to claim 4, characterized in that, In step S10, the weight W of each region i Calculated using the following formula: W i =V i *2.533 / 10 6 In the formula, V is the volume of the solution inside the quartz crucible.

6. The liquid outlet distance control method according to claim 2, characterized in that, In step S10, the Ratio value is obtained according to the following formula: Ratio = d 2 / b i 2 *(1-e), where: d: single crystal diameter, e: deformation amount 6%-8%; b i =2*√(R2) 2 -(H B *X / Y) 2 +(D / 2)-R2, where X: ranges from 0 to Y, H B The height value of each region after region B is divided into regions Y.

7. The liquid outlet distance control method according to claim 6, characterized in that, In step S10, the rising speed F of the liquid level inside the crucible i Calculated using the following formula: F i =Ratio*Z, where Z: seed crystal rising speed.

8. The liquid outlet distance control method according to claim 5, characterized in that, In step S20, the "weight M of single crystal grown per unit time T" is calculated using the following formula: M = T * S * (d / 2) 2 *π*2.329 / 10 -6 In the formula: d: single crystal diameter.

9. The liquid outlet distance control method according to claim 8, characterized in that, In step S20, the "compensation height △H" is calculated using the following formula: △H=M*(H i / W i )。 10. The liquid outlet distance control method according to claim 1, characterized in that, In step S20, the unit time T is an integer multiple of the instantaneous seed crystal growth rate, and this integer multiple is ≤5.

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