Method and system for controlling growth of multiple continuously pulled single crystal silicon

Abstract

The application discloses a multi-continuous single crystal silicon growth control method and system, and belongs to the technical field of single crystal silicon rod drawing. The method dynamically allocates the constant diameter length of each single crystal rod according to the impurity accumulation characteristics of the melt, and determines the secondary supplementary feeding amount according to the allocated length, so that the melt quality after the last time of supplementary feeding is always less than the previous time. Specifically, the planned continuous drawing total number and the standard length are set, the theoretical maximum total drawing length is determined according to the thermal field structure; the length of each crystal rod is unevenly allocated in a manner that the front length is longer and the rear length is shorter; the supplementary feeding amount is determined according to the allocated length; the melt quality after supplementary feeding is controlled to be not more than the melt quality after the last time of supplementary feeding of the previous crystal rod, so that the initial liquid level height of the next crystal rod is always not higher than the previous one. Through the synergistic effect of length uneven allocation and liquid level height descending control, the application effectively reduces the impurity flushing introduction of the crucible wall, reduces the NG rate in the continuous drawing process, and improves the single crystal silicon rod drawing yield and the whole rod rate.

Description

Technical Field

[0001] This invention belongs to the field of single-crystal silicon rod pulling technology, specifically relating to a method and system for controlling the growth of multi-rod single-crystal silicon rods. Background Technology

[0002] In recent years, with the rapid development of the semiconductor industry and the increasing demand for semiconductor silicon components, the requirements for the production efficiency of monocrystalline silicon rods have also gradually increased. At present, monocrystalline silicon rods are mainly pulled from molten polycrystalline silicon using the Czochralski (CZ) method. This method has become the mainstream due to its high efficiency and controllability. In order to further reduce costs and improve efficiency, the industry has begun to adopt the "multi-rod pulling" technology.

[0003] For example, the prior art with patent application number 202610301294.4 and invention title: Method for pulling multiple 6-inch heavily doped crystal rods using a 24-inch hot field provides the following technical solution: S1: In the MCZ process based on a 24-inch hot field, the pulling speed, crystal rotation speed, and crucible rotation speed of crystal rods with different equal diameter lengths are preset during the equal diameter process; during the equal diameter crystal pulling process, multiple crystal rods are pulled according to the preset pulling speed, crystal rotation speed, and crucible rotation speed of crystal rods with different equal diameter lengths, so as to suppress complex thermal convection, avoid loss of control of doping uniformity, and systematically reduce the introduction and transport efficiency of oxygen.

[0004] In the above-mentioned technology, by controlling the pulling speed of the crystal rod, the rotation speed of the crystal, and the rotation speed of the crucible during the pulling process of multiple crystal rods, the generation of thermal convection is suppressed and the introduction of oxygen impurities is avoided. However, the following technical problems still exist: During the pulling of single crystal silicon, impurities in the silicon melt will continue to accumulate on the wall surface of the contact crucible. When replenishing the material, the melt disturbance caused by the melting of the new material will wash away the inner wall of the crucible. Impurities on the crucible wall are washed into the melt, resulting in the gradual accumulation of impurities in the melt. Excessive impurities cause no good (NG) during the pulling process of single crystal silicon rods, which seriously affects the pulling yield of continuous single crystal silicon rods. Summary of the Invention

[0005] In view of this, the present invention provides a method for controlling the growth of multi-strand single-crystal silicon to solve the problem that the crystal rods pulled after re-pulling are prone to NG (non-completion) during the continuous pulling process of single-crystal silicon rods.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] This invention provides a method for controlling the growth of multi-strand monocrystalline silicon. The method dynamically allocates the equal diameter length of each monocrystalline rod according to the characteristics of melt impurity accumulation, and determines the amount of secondary material replenishment for each monocrystalline rod based on the allocated monocrystalline rod length. This ensures that the melt mass after replenishment is less than the initial material replenishment mass when pulling the second monocrystalline rod, and that the melt mass after subsequent replenishment is less than the melt mass after previous replenishment when pulling subsequent monocrystalline rods.

[0008] The present invention also provides a method for controlling the growth of multi-strand single-crystal silicon, comprising the following steps:

[0009] S1. Set the total number N of single-crystal silicon rods to be continuously pulled in a single crucible and the standard single-rod pulling length L. std The theoretical maximum total tensile length L is determined based on the thermal field structure. total ;

[0010] S2, based on the maximum total drawing length L total Total number of single-crystal silicon rods N, standard single-rod drawing length L std According to predetermined standards, the length of each monocrystalline silicon rod is non-uniformly distributed with a longer front and shorter back to obtain the length L of each monocrystalline silicon rod. I ;

[0011] S3. Based on the pulling length L of each single-crystal silicon rod I Determine the quality of supplementary material M add After each single-crystal silicon rod is pulled, the remaining melt volume W is obtained. RESIDUE ;

[0012] S4, according to W RESIDUE +M add ≤W TOTAL The strategy controls the continuous pulling of multiple monocrystalline silicon rods to ensure that the initial liquid level height during the growth of the next rod is never higher than the initial liquid level height during the growth of the previous rod; where W TOTAL The mass of the melt in the crucible after adding material when pulling the next single-crystal silicon rod.

[0013] Preferably, the maximum total drawing length L mentioned in step S1 total The calculation formula is , of which M total For total feed amount, M residue ρ represents the remaining feed amount, ρ represents the melt density, and A represents the cross-sectional area of ​​the pulled crystal rod.

[0014] Preferably, the predetermined standard in step S2 is: the drawing length L of the tail bar monocrystalline silicon rod. LAST Satisfy L LAST ≤L std The drawing length L of a non-tailed single-crystal silicon rod PRE Satisfy L PRE ≥L std And the length L of each single-crystal silicon rod I The sum is approximately equal to the maximum total drawing length L. total .

[0015] Preferably, the M mentioned in step S3 add The calculation formula is M add =M(LI )+ΔM loss , where M(L I ) for L I Mass of a single-crystal silicon rod of length, ΔM loss This is for compensation of volatiles and residues.

[0016] Preferably, the ΔM loss Satisfy the following condition: The shorter the planned length of the single-crystal silicon rod, the greater the amount of residual material compensation ΔM. loss The fewer.

[0017] The present invention also provides a multi-strand continuous single crystal silicon growth control system, comprising: a maximum total pulling length determination module, a single single crystal silicon rod length allocation module, a material replenishment amount determination module, and a continuous pulling control module;

[0018] The maximum total drawing length determination module is configured to set the total number N of single-crystal silicon rods to be continuously drawn in a single crucible and the standard single-rod drawing length L. std The theoretical maximum total tensile length L is determined based on the thermal field structure. total ;

[0019] The single-crystal silicon rod length allocation module is configured to allocate lengths based on the maximum total drawing length L. total Total number of single-crystal silicon rods N, standard single-rod drawing length L std According to predetermined standards, the length of each monocrystalline silicon rod is non-uniformly distributed with a longer front and shorter back to obtain the length L of each monocrystalline silicon rod. I ;

[0020] The replenishment amount determination module is configured to determine the amount of material added based on the pulling length L of each single crystal silicon rod. I Determine the quality of supplementary material M add After each single-crystal silicon rod is pulled, the remaining melt volume W is obtained. RESIDUE ;

[0021] The continuous drawing control module is configured to follow W RESIDUE +M add ≤W TOTAL The strategy controls the continuous pulling of multiple monocrystalline silicon rods to ensure that the initial liquid level height during the growth of the next rod is never higher than the initial liquid level height during the growth of the previous rod; where W TOTAL The mass of the melt in the crucible after adding material when pulling the next single-crystal silicon rod.

[0022] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the above-described multi-strand single-crystal silicon growth control method.

[0023] The present invention also provides a computing device, including a memory and a processor, wherein the memory stores executable code, and when the processor executes the executable code, it implements the above-described method for controlling the growth of multi-strand single-crystal silicon.

[0024] In the aforementioned method and system for controlling the growth of multi-strand monocrystalline silicon, the amount of material added before pulling each monocrystalline silicon rod is determined based on its pulling length. Furthermore, the melt height before pulling each monocrystalline silicon rod is limited to be lower than the melt height before pulling the previous monocrystalline silicon rod. This addresses the problem of melt disturbance scouring the inner wall of the crucible, which washes impurities accumulated on the inner wall into the melt, leading to an increased NG rate during the monocrystalline silicon rod pulling process. Moreover, under the constraint that the sum of the total pulling lengths of the monocrystalline silicon rods is approximately equal to the maximum pulling length, the pulling length of each monocrystalline silicon rod is non-uniformly distributed by setting the pulling length of the tail rod to be less than the standard pulling length and the pulling length of the non-tail rods to be greater than the standard pulling length. This ensures that longer monocrystalline silicon rods are pulled when the impurity content is low before melt replenishment, and that the pulling length of subsequent monocrystalline silicon rods is reduced after melt replenishment when the impurity content increases, thereby lowering the NG probability of subsequent monocrystalline silicon rods. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the melt height after multiple feedings according to the present invention.

[0026] Figure 2 This is a schematic diagram illustrating the multiple pulling processes of each crystal rod in this invention.

[0027] Figure 3 This is a schematic diagram showing the yield of single-crystal silicon rods in embodiments and comparative examples of the present invention. Detailed Implementation

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Please refer to Figures 1 to 2 This invention provides a method for controlling the growth of multi-strand monocrystalline silicon. The method dynamically allocates the equal diameter length of each monocrystalline rod according to the characteristics of melt impurity accumulation, and determines the amount of secondary material replenishment for each monocrystalline rod based on the allocated monocrystalline rod length. This ensures that the melt mass after replenishment is less than the initial material replenishment mass when the second rod is pulled, and that the melt mass after subsequent replenishment is less than the melt mass after previous replenishment when pulling subsequent rods.

[0030] Furthermore, the present invention also provides a method for controlling the growth of multi-strand single-crystal silicon, comprising the following steps:

[0031] S1. Set the total number N of single-crystal silicon rods to be continuously pulled in a single crucible and the standard single-rod pulling length L. std The theoretical maximum total tensile length L is determined based on the thermal field structure. total The formula for calculating the theoretical maximum total drawing length is as follows: M total For total feed amount, M residue Where ρ is the remaining feed amount, ρ is the melt density, and A is the cross-sectional area of ​​the pulled crystal rod;

[0032] S2, based on the maximum total drawing length L total Total number of single-crystal silicon rods N, standard single-rod drawing length L std According to the drawing length L of the tail bar single crystal silicon rod LAST ≤L std The drawing length L of a non-tailed single-crystal silicon rod PRE ≥L std Furthermore, the constraint condition ∑L is satisfied. I ≈L total That is, the length L of each single-crystal silicon rod I The sum is approximately equal to the maximum total drawing length L. total In this process, by limiting the pulling length of each single-crystal silicon rod under certain constraints, non-uniform distribution of the single-crystal silicon rods is achieved, thereby obtaining the pulling length L of each single-crystal silicon rod. I ;

[0033] S3. Based on the length L drawn for each single-crystal silicon rod I Determine the quality of supplementary material M add After each single-crystal silicon rod is pulled, the remaining melt volume W is obtained. RESIDUE , of which M add =M(L I )+ΔM loss , where M(L I ) for L I Mass of a single-crystal silicon rod of length, ΔM loss ΔM is the amount of volatile matter and residual material compensation. loss The shorter the planned length of the single-crystal silicon rod, the greater the amount of residual material compensation ΔM. loss The less;

[0034] S4, according to W RESIDUE +M add ≤W TOTAL The strategy controls the continuous pulling of multiple monocrystalline silicon rods to ensure that the initial liquid level height during the growth of the next rod is never higher than the initial liquid level height during the growth of the previous rod; where W TOTAL The mass of the melt in the crucible after adding material when pulling the next single-crystal silicon rod.

[0035] Furthermore, the present invention also provides a multi-strand continuous single crystal silicon growth control system, including: a maximum total pulling length determination module, a single single crystal silicon rod length allocation module, a material replenishment amount determination module, and a continuous pulling control module;

[0036] The maximum total drawing length determination module is configured to set the total number N of single-crystal silicon rods to be continuously drawn in a single crucible and the standard single-rod drawing length L. std The theoretical maximum total tensile length L is determined based on the thermal field structure. total ;

[0037] The single-crystal silicon rod length allocation module is configured to allocate lengths based on the maximum total drawing length L. total Total number of single-crystal silicon rods N, standard single-rod drawing length L std According to predetermined standards, the length of each monocrystalline silicon rod is non-uniformly distributed with a longer front and shorter back to obtain the length L of each monocrystalline silicon rod. I ;

[0038] The replenishment amount determination module is configured to determine the amount of material added based on the pulling length L of each single crystal silicon rod. I Determine the quality of supplementary material M add After each single-crystal silicon rod is pulled, the remaining melt volume W is obtained. RESIDUE ;

[0039] The continuous drawing control module is configured to follow W RESIDUE +M add ≤W TOTAL The strategy controls the continuous pulling of multiple monocrystalline silicon rods to ensure that the initial liquid level height during the growth of the next rod is never higher than the initial liquid level height during the growth of the previous rod; where W TOTAL The mass of the melt in the crucible after adding material when pulling the next single-crystal silicon rod.

[0040] Furthermore, the present invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed in a computer, causes the computer to perform the above-described multi-strand single-crystal silicon growth control method.

[0041] Furthermore, the present invention also provides a computing device, including a memory and a processor, wherein the memory stores executable code, and when the processor executes the executable code, it implements the above-mentioned multi-strand single-crystal silicon growth control method.

[0042] For step S1, the total number N of single-crystal silicon rods to be continuously pulled in a single crucible and the standard single-rod pulling length L are set. std The theoretical maximum total tensile length L is determined based on the thermal field structure. total The formula for calculating the theoretical maximum total drawing length is as follows: M total For total feed amount, M residue ρ represents the remaining feed amount, ρ represents the melt density, and A represents the cross-sectional area of ​​the pulled crystal rod.

[0043] In this step, the maximum total drawing length of the single-crystal silicon rod is calculated based on the thermal field structure, and the total number of single-crystal silicon rods to be drawn in a single crucible and the standard drawing length of a single rod are set to determine the basic parameters for drawing multiple single-crystal silicon rods in a row.

[0044] For step S2, based on the maximum total drawing length L total Total number of single-crystal silicon rods N, standard single-rod drawing length L std According to the drawing length L of the tail bar single crystal silicon rod LAST ≤L std The drawing length L of a non-tailed single-crystal silicon rod PRE ≥L std Furthermore, the constraint condition ∑L is satisfied. I ≈L total That is, the length L of each single-crystal silicon rod I The sum is approximately equal to the maximum total drawing length L. total In this process, by limiting the pulling length of each single-crystal silicon rod under certain constraints, non-uniform distribution of the single-crystal silicon rods is achieved, thereby obtaining the pulling length L of each single-crystal silicon rod. I .

[0045] In this step, when allocating the pulling length for each single-crystal silicon rod, it is considered that as the pulling of the single-crystal silicon rod proceeds, impurities gradually accumulate in the melt inside the crucible. The increase in impurities increases the NG rate of single-crystal silicon rod pulling. To solve this problem, the pulling length of each single-crystal silicon rod is approximately equal to the theoretical maximum total pulling length L. total Under the constraints, the pulling length of the tail-bar monocrystalline silicon rod is made shorter than the standard pulling length, while the pulling length of the non-tail-bar monocrystalline silicon rod is longer than the standard pulling length. This achieves a non-uniform distribution of pulling length. That is, when there are not many impurities accumulated in the melt in the crucible, a longer crystal rod is selected for pulling, and when there are many impurities accumulated in the melt in the crucible, a shorter crystal rod is selected for pulling. This is to achieve a high-quality output of non-tail-bars by sacrificing part of the tail-bar length while ensuring that the total output does not decrease. At the same time, it reduces the NG rate of each monocrystalline silicon rod pulling process.

[0046] For step S3, based on the pulling length L of each single-crystal silicon rod I Determine the quality of supplementary material M add After each single-crystal silicon rod is pulled, the remaining melt volume W is obtained. RESIDUE , of which M add =M(L I )+ΔM loss , where M(LI ) for L I Mass of a single-crystal silicon rod of length, ΔM loss ΔM is the amount of volatile matter and residual material compensation. loss The shorter the planned length of the single-crystal silicon rod, the greater the amount of residual material compensation ΔM. loss The fewer.

[0047] In this step, the amount of material to be added is calculated based on the pulling length of each monocrystalline silicon rod. Considering the losses during the pulling process, after calculating the standard amount of material to be added for each monocrystalline silicon rod, a residual material compensation amount ΔM is added. loss Furthermore, the shorter the pulling length of the single-crystal silicon rod, the greater the increase in residual material compensation ΔM. loss The fewer.

[0048] For step S4, according to W RESIDUE +M add ≤W TOTAL The strategy controls the continuous pulling of multiple monocrystalline silicon rods to ensure that the initial liquid level height during the growth of the next rod is never higher than the initial liquid level height during the growth of the previous rod; where W TOTAL The mass of the melt in the crucible after adding material when pulling the next single-crystal silicon rod.

[0049] In this step, considering that during the single-crystal silicon rod pulling process, impurities in the melt will accumulate on the surface where the melt contacts the inner wall of the crucible, and as the single-crystal silicon rod is pulled and the melt height decreases, impurities will adhere to the inner wall of the crucible. During the feeding process, the disturbance of the melt will wash away the inner wall of the crucible, washing the impurities on the inner wall of the crucible into the melt. With the continuous pulling of single-crystal silicon rods, more and more impurities accumulate in the melt. Excessive impurities seriously affect the quality of the pulled single-crystal silicon rods and increase the NG rate of the single-crystal silicon rod pulling process. Therefore, the liquid level height after feeding is limited so that the initial liquid level height of the next crystal rod growth is never higher than the initial liquid level height of the previous crystal rod growth, in order to avoid the melt washing away the impurities attached to the inner wall of the crucible and reduce the amount of impurities accumulated in the melt.

[0050] Thus, this invention reduces the no-noise rate (NG) in the continuous pulling process by non-uniformly distributing the length of each single-crystal silicon rod. This is achieved when there is less impurity accumulation in the melt, resulting in longer, higher-quality single-crystal silicon rods, and when there is more impurity accumulation in the melt, resulting in shorter single-crystal silicon rods. Furthermore, by strictly limiting the melt level during each replenishment, the melt is prevented from washing away impurities adhering to the inner wall of the crucible, reducing the amount of impurities accumulated in the melt. Through these methods, the overall NG rate of continuously pulled single-crystal silicon rods is reduced.

[0051] To facilitate understanding of the technical concept and patentability of this application, the following embodiments are further provided:

[0052] Example 1

[0053] This embodiment provides a method for controlling the pulling of two connected single-crystal silicon rods, the specific steps of which are as follows:

[0054] S1. Set the total number of single-crystal silicon rods to be continuously pulled in a single crucible to N=2, divided into rod A and rod B, with a standard single-rod pulling length L. std The theoretical maximum total tensile length L is determined based on the thermal field structure. total The formula for calculating the theoretical maximum total drawing length is as follows: M total For total feed amount, M residue Where ρ is the remaining feed amount, ρ is the melt density, and A is the cross-sectional area of ​​the pulled crystal rod;

[0055] S2, based on the maximum total drawing length L total Total number of single-crystal silicon rods N=2, standard single-rod drawing length L std According to the drawing length L of bar B B ≤L std The drawing length L of rod A A ≥L std Furthermore, the constraint condition ∑L is satisfied. I ≈L total L A +L B ≈L total To obtain the drawing length L of rods A and B. A and L B ;

[0056] S3. Based on the drawing length L of rods A and B. A and L B Determine the quality of supplementary material M add After rod A is drawn, the remaining melt volume W is obtained. RESIDUE , of which M add =M(L I )+ΔM loss , where M(L I ) for L I Mass of a single-crystal silicon rod of length, ΔM loss ΔM is the amount of volatile matter and residual material compensation. loss The shorter the planned length of the single-crystal silicon rod, the greater the amount of residual material compensation ΔM. loss The less;

[0057] S4, according to W RESIDUE +M add ≤W TOTALThe strategy controls the continuous pulling of multiple monocrystalline silicon rods to ensure that the initial liquid level height during the growth of rod B is not higher than the initial liquid level height during the growth of rod A; where W TOTAL The mass of the melt in the crucible after adding material when pulling the next single-crystal silicon rod.

[0058] Example 2

[0059] This embodiment provides a method for controlling the pulling of three interconnected single-crystal silicon rods, the specific steps of which are as follows:

[0060] S1. Set the total number of single-crystal silicon rods to be continuously pulled in a single crucible to N=3, divided into rods A, B and C, with a standard single-rod pulling length L. std The theoretical maximum total tensile length L is determined based on the thermal field structure. total The formula for calculating the theoretical maximum total drawing length is as follows: M total For total feed amount, M residue Where ρ is the remaining feed amount, ρ is the melt density, and A is the cross-sectional area of ​​the pulled crystal rod;

[0061] S2, based on the maximum total drawing length L total Total number of single-crystal silicon rods N=3, standard single-rod drawing length L std According to the drawing length L of C rod C ≤L std The drawing length L of rod A A ≥L std The drawing length L of bar B std ≤L B ≤L A Furthermore, the constraint condition ∑L is satisfied. I ≈L total L A +L B +L C ≈L total To obtain the drawing length L of rods A, B, and C. A L B and L C ;

[0062] S3. Based on the drawing length L of rods A, B, and C. A L B and L C Determine the quality of supplementary material M add After each single-crystal silicon rod is pulled, the remaining melt volume W is obtained. RESIDUE , of which M add =M(L I )+ΔM loss , where M(L I ) for L IMass of a single-crystal silicon rod of length, ΔM loss ΔM is the amount of volatile matter and residual material compensation. loss The shorter the planned length of the single-crystal silicon rod, the greater the amount of residual material compensation ΔM. loss The less;

[0063] S4, according to W RESIDUE +M add ≤W TOTAL The strategy controls the continuous pulling of multiple monocrystalline silicon rods to ensure that the initial liquid level height during the growth of rod B is no higher than that during the growth of rod A, and the initial liquid level height during the growth of rod C is no higher than that during the growth of rod B; where W TOTAL The mass of the melt in the crucible after adding material when pulling the next single-crystal silicon rod.

[0064] Comparative Example 1

[0065] This comparative example provides a traditional method for controlling the pulling of two connected monocrystalline silicon rods. The specific steps are as follows:

[0066] S1. Set the total number of single-crystal silicon rods to be continuously pulled in a single crucible to N=2, divided into rod A and rod B, with a standard single-rod pulling length L. std The theoretical maximum total tensile length L is determined based on the thermal field structure. total The formula for calculating the theoretical maximum total drawing length is as follows: M total For total feed amount, M residue Where ρ is the remaining feed amount, ρ is the melt density, and A is the cross-sectional area of ​​the pulled crystal rod;

[0067] S2, based on the maximum total drawing length L total Total number of single-crystal silicon rods N=2, standard single-rod drawing length L std According to the drawing length L of rod A A ≤L std The drawing length L of bar B B ≥L std ;

[0068] S3. Based on the drawing length L of rods A and B. A and L B Determine the quality of supplementary material M add After rod A is drawn, the remaining melt volume W is obtained. RESIDUE , of which M add =M(L I )+ΔM loss , where M(L I ) for L I Mass of a single-crystal silicon rod of length, ΔM loss ΔM is the amount of volatile matter and residual material compensation. lossThe shorter the planned length of the single-crystal silicon rod, the greater the amount of residual material compensation ΔM. loss The fewer.

[0069] Comparative Example 2

[0070] This comparative example provides a traditional method for controlling the pulling of three interconnected single-crystal silicon rods. The specific steps are as follows:

[0071] S1. Set the total number of single-crystal silicon rods to be continuously pulled in a single crucible to N=3, divided into rods A, B and C, with a standard single-rod pulling length L. std The theoretical maximum total tensile length L is determined based on the thermal field structure. total The formula for calculating the theoretical maximum total drawing length is as follows: M total For total feed amount, M residue Where ρ is the remaining feed amount, ρ is the melt density, and A is the cross-sectional area of ​​the pulled crystal rod;

[0072] S2, based on the maximum total drawing length L total Total number of single-crystal silicon rods N=3, standard single-rod drawing length L std According to the drawing length L of rod A A ≤L std The drawing length L of the C-bar C ≥L std The drawing length L of bar B std ≥L B ≥L A To obtain the drawing length L of rods A, B, and C. A L B and L C ;

[0073] S3. Based on the drawing length L of rods A, B, and C. A L B and L C Determine the quality of supplementary material M add After each single-crystal silicon rod is pulled, the remaining melt volume W is obtained. RESIDUE , of which M add =M(L I )+ΔM loss , where M(L I ) for L I Mass of a single-crystal silicon rod of length, ΔM loss ΔM is the amount of volatile matter and residual material compensation. loss The shorter the planned length of the single-crystal silicon rod, the greater the amount of residual material compensation ΔM. loss The fewer.

[0074] Please refer to Figure 3Under a two-drawing process, the comparative yield was 74.30%, while the drawing yield of this embodiment was 83.10%, an increase of 8.8 percentage points, with a whole bar yield of 80.00%. Under a three-drawing process, the comparative yield was 75.80%, while the drawing yield of this embodiment was 85.30%, an increase of 9.5 percentage points, with a whole bar yield of 83.30%. Furthermore, while significantly improving the yield, the whole bar yield also increased synchronously with the increase in the number of drawn bars, proving that the high yield did not come at the expense of product integrity, but rather achieved a dual synergistic optimization of yield and quality.

[0075] In summary, this invention employs a non-uniform "longer at the beginning, shorter at the end" distribution of the length of each continuously pulled single-crystal silicon rod. This allows for a longer pulling process in the initial stage when impurities are less accumulated, while proactively shortening the pulling length in the later stage when impurities are more concentrated. This effectively reduces the risk of individual rods being scrapped due to excessive impurities, while maintaining overall yield. Simultaneously, this invention strictly limits the mass of the melt in the crucible after a second feeding to no more than the mass of the melt after feeding the previous rod. This ensures that the initial liquid level of the subsequent rod is never higher than that of the previous rod, preventing excessive scouring of impurities on the crucible wall by feeding disturbances and reducing impurity accumulation in the melt. Through the synergistic effect of these two core mechanisms, the no-no (NG) rate of continuously pulled single-crystal silicon rods is reduced.

[0076] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that all or part of the processes for implementing the above embodiments and equivalent variations made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for controlling the growth of multi-strand continuous single-crystal silicon, characterized in that, The equal diameter length of each single crystal rod is dynamically allocated according to the characteristics of melt impurity accumulation, and the amount of secondary replenishment material for drawing each single crystal rod is determined according to the allocated single crystal rod length, so that the melt mass after replenishment material is less than the mass of the first replenishment material when drawing the second crystal rod, and the melt mass after the second replenishment material is less than the melt mass after the first replenishment material when drawing subsequent crystal rods.

2. A method for controlling the growth of multi-strand continuous single-crystal silicon, characterized in that, Includes the following steps: S1. Set the total number N of single-crystal silicon rods to be continuously pulled in a single crucible and the standard single-rod pulling length L. std The theoretical maximum total tensile length L is determined based on the thermal field structure. total ; S2, based on the maximum total drawing length L total Total number of single-crystal silicon rods N, standard single-rod drawing length L std According to predetermined standards, the length of each monocrystalline silicon rod is non-uniformly distributed with a longer front and shorter back to obtain the length L of each monocrystalline silicon rod. I ; S3. Based on the pulling length L of each single-crystal silicon rod I Determine the quality of supplementary material M add After each single-crystal silicon rod is pulled, the remaining melt volume W is obtained. RESIDUE ; S4, according to W RESIDUE +M add ≤W TOTAL The strategy controls the continuous pulling of multiple monocrystalline silicon rods to ensure that the initial liquid level height during the growth of the next rod is never higher than the initial liquid level height during the growth of the previous rod; where W TOTAL The mass of the melt in the crucible after adding material when pulling the next single-crystal silicon rod.

3. The method for controlling the growth of multi-strand single-crystal silicon according to claim 2, characterized in that, The maximum total drawing length L mentioned in step S1 total The calculation formula is , of which M total For total feed amount, M residue ρ represents the remaining feed amount, ρ represents the melt density, and A represents the cross-sectional area of ​​the pulled crystal rod.

4. The method for controlling the growth of multi-strand single-crystal silicon according to claim 2, characterized in that, The predetermined standard mentioned in step S2 is: the drawing length L of the tail bar single crystal silicon rod. LAST Satisfy L LAST ≤L std The drawing length L of a non-tailed single-crystal silicon rod PRE Satisfy L PRE ≥L std And the length L of each single-crystal silicon rod I The sum is approximately equal to the maximum total drawing length L. total .

5. The method for controlling the growth of multi-strand single-crystal silicon according to claim 2, characterized in that, The replenishment mass M mentioned in step S3 add The calculation formula is M add =M(L I )+ΔM loss , where M(L I ) for L I Mass of a single-crystal silicon rod of length, ΔM loss This is for compensation of volatiles and residues.

6. The method for controlling the growth of multi-strand single-crystal silicon according to claim 2, characterized in that, The ΔM loss Satisfy the following condition: The shorter the planned length of the single-crystal silicon rod, the greater the amount of residual material compensation ΔM. loss The fewer.

7. A multi-strand continuous single-crystal silicon growth control system, characterized in that, include: Maximum total drawing length determination module, single monocrystalline silicon rod length allocation module, material replenishment amount determination module, continuous drawing control module; The maximum total drawing length determination module is configured to set the total number N of single-crystal silicon rods to be continuously drawn in a single crucible and the standard single-rod drawing length L. std The theoretical maximum total tensile length L is determined based on the thermal field structure. total ; The single-crystal silicon rod length allocation module is configured to allocate lengths based on the maximum total drawing length L. total Total number of single-crystal silicon rods N, standard single-rod drawing length L std According to predetermined standards, the length of each monocrystalline silicon rod is non-uniformly distributed with a longer front and shorter back to obtain the length L of each monocrystalline silicon rod. I ; The replenishment amount determination module is configured to determine the amount of material added based on the pulling length L of each single crystal silicon rod. I Determine the quality of supplementary material M add After each single-crystal silicon rod is pulled, the remaining melt volume W is obtained. RESIDUE ; The continuous drawing control module is configured to follow W RESIDUE +M add ≤W TOTAL The strategy controls the continuous pulling of multiple monocrystalline silicon rods to ensure that the initial liquid level height during the growth of the next rod is never higher than the initial liquid level height during the growth of the previous rod; where W TOTAL The mass of the melt in the crucible after adding material when pulling the next single-crystal silicon rod.

8. A computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the method as described in any one of claims 1-6.

9. A computing device, comprising a memory and a processor, wherein executable code is stored in the memory, and when the processor executes the executable code, it implements the method as described in any one of claims 1-6.

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