Crystal pulling method of single crystal silicon rod and single crystal silicon rod

Abstract

The crystal pulling method of the single crystal silicon rod comprises the following steps that polycrystalline silicon is put into a crucible of a crystal pulling furnace to be melted, seed crystal rotation and upward pulling are carried out, crystal guiding is completed, shouldering is carried out, in the shouldering process, the shouldering diameter dn and the shouldering length Ln are measured, the current pulling speed is SLn, and after t0 time, the current pulling speed is SLn; measuring the shouldering diameter dn + 1 and the shouldering length Ln + 1, calculating the shouldering slope delta p according to a formula delta p = (dn + 1-dn) / (Ln + 1-Ln), when the shouldering length is a preset length L, delta p is greater than or equal to a preset slope, or delta p is increased to the preset slope within t1, judging that the silicon single crystal rod is split, and when the shouldering length is the preset length L, if the shouldering slope delta p is smaller than the preset slope, judging that the silicon single crystal rod is split. When the delta p is larger than or equal to the preset slope and lasts for t1, it is judged that the single crystal silicon rods are not split, the current pulling speed SLn + 2 is controlled to be smaller than SLn + 1 till delta p is larger than or equal to the preset slope, and the shoulder shapes of the single crystal silicon rods machined in different machining batches are kept consistent through the method.

Description

Technical Field

[0001] The invention relates to the technical field of single crystal silicon, in particular to a crystal pulling method for a single crystal silicon rod and a single crystal silicon rod. Background Art

[0002] The traditional shouldering process adjusts the shouldering parameters according to the crystal growth temperature and the actual crystal growth pulling speed. At present, in the actual production shouldering process, the crucible lifting speed is often a fixed value, and the activation time of the fixed crucible lifting affects the shouldering opening timing, which in turn affects the shoulder shape and subsequent shoulder breaking probability. Therefore, it is easy to cause different batches of crystal rods to have different opening times during the production process, which in turn causes the risk of inconsistent shoulder shapes, increasing the risk of inconsistent production data of single crystal silicon rods due to process changes. Summary of the invention

[0003] The present application provides a single crystal silicon rod pulling method and a single crystal silicon rod, which are used to solve the problem that different batches of crystal rods produced in the shouldering process have different fork opening times and inconsistent shoulder shapes.

[0004] In a first aspect, the present application provides a method for pulling a single crystal silicon rod, the method comprising the following steps: Put polysilicon into the crucible of the crystal pulling furnace to melt; The seed crystal is rotated and pulled upward to complete the seeding and shoulder release; During the shoulder release process, measure the shoulder release diameter d n And shoulder length L n , and the current pulling speed is SL n After t0 time, measure the shoulder diameter d n+1 And shoulder length L n+1 , and the current pulling speed is SL n+1 ; According to the formula Δp=(d n+1 -d n ) / (L n+1 -L n ), calculate the shoulder slope Δp; When the shoulder length is the preset length L, Δp is greater than or equal to the preset slope, or, within t1, Δp increases to the preset slope, it is determined that the single crystal silicon rod is forked; When the shoulder length is the preset length L, if the shoulder slope Δp is less than the preset slope and lasts for t1, it is determined that the single crystal silicon rod is not forked, and the current pulling speed SL is controlled. n+2 <SL n+1 , until Δp is greater than or equal to the preset slope.

[0005] In this scheme, the shoulder slope Δp value of the single crystal silicon rod is used to determine whether the single crystal silicon rod is forked, so that the pulling speed can be adjusted in time to control the shoulder and fork timing of the single crystal silicon rod, and then the fork timing of the single crystal silicon rods in different furnaces can be adjusted in time. Therefore, the shoulder and fork of the single crystal silicon rod are judged and adjusted to be consistent through the above method, so that the shoulder shape of the single crystal silicon rods processed from different processing batches is consistent, thereby improving the consistency and reproducibility of the single crystal silicon rods of the same specification processed from different processing batches, and making the shapes of the same positions of different single crystal silicon rods consistent, that is, the data uniformity of the single crystal silicon rods of the same specification can be improved, thereby improving the production quality and data accuracy of the single crystal silicon rods. At the same time, in the use of different shoulder release processes, the above method can avoid the risk of reduced production data of single crystal silicon rods due to process changes.

[0006] In this solution, 50mm≤L≤60mm.

[0007] In this solution, the preset slope is 1.1.

[0008] In this solution, 0.4s≤t0≤0.6s, and / or, 25s≤t1≤35s.

[0009] In this scheme, during the shoulder release process, the real-time crucible lifting speed CL satisfies:

[0010] Where D is the inner diameter of the crucible, d is the current shoulder diameter, and SL is the current pulling speed.

[0011] In this solution, when the shoulder length is the preset length L and equal to 55 mm, the actual shoulder diameter is 45.9 mm, the simulated crucible heel ratio is 0.0023, the actual crucible lifting speed is 0.13 mm / hr, and the actual pulling speed is 58 mm / hr.

[0012] In this solution, during the shoulder release process, the crystal pulling method further includes: The actual pulling speed of the single crystal silicon rod is adjusted by a proportional-integral-differential control system so that the real-time crucible lifting speed CL matches the current pulling speed SL of the single crystal silicon rod.

[0013] In this scheme, adjusting the actual pulling speed of the single crystal silicon rod by a proportional integral differential control system includes the following steps: Calculate the difference between the current shoulder diameter slope and the basic shoulder diameter slope; If the difference between the current shoulder diameter slope and the basic shoulder diameter slope is less than a preset value, the proportional integral differential control system controls the current pulling speed of the single crystal silicon rod to increase, and the current pulling speed is the pulling speed corresponding to the current shoulder slope; If the difference between the current shoulder diameter slope and the basic shoulder diameter slope is greater than a preset value, the proportional integral differential control system controls the current pulling speed of the single crystal silicon rod to decrease, and the current pulling speed is the pulling speed corresponding to the current shoulder slope.

[0014] In this scheme, the distance between the liquid inlet and outlet is M, which satisfies 30mm≤M≤32mm, and the average pulling speed of the crystal is V, which satisfies 260mm / hr≤V≤300mm / hr.

[0015] A second aspect of the present application provides a single crystal silicon rod, which is prepared by the above-mentioned single crystal silicon rod pulling method.

[0016] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of a crystal pulling method provided in the present application in a specific embodiment; Figure 2 A shoulder slope curve diagram of a single crystal silicon rod provided in the present application in a specific embodiment; Figure 3 A furnace pulling speed curve diagram of a specific embodiment of preparing a single crystal silicon rod in the prior art; Figure 4 A graph showing a furnace pulling speed in a specific embodiment of preparing a single crystal silicon rod by the crystal pulling method provided by the present application; The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application. DETAILED DESCRIPTION

[0018] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0019] In a specific embodiment, the present application is further described in detail below through specific embodiments and in conjunction with the accompanying drawings.

[0020] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0021] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0022] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0023] It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described at the angles shown in the accompanying drawings and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0024] The crystal pulling process for preparing single crystal silicon rods usually includes seeding, shouldering, shoulder rotation, equal diameter, and finishing. Seeding is to heat and melt the polycrystalline silicon in the quartz crucible, and enter the melt through the seed crystal, and then pull the seed crystal out of the crystal. Shouldering is to control the crystal to the required diameter. Shoulder rotation means to increase the pulling speed after shouldering is completed to make the crystal grow longitudinally. Equal diameter means to control the equal diameter growth of the crystal to the required length according to the conditions of the melt and the crystal pulling furnace. Finishing means to gradually reduce the diameter, leave the melt, and then complete the preparation of single crystal silicon rods.

[0025] In the process of producing single crystal silicon rods of the same specification, it is often necessary to process them through different furnaces, that is, different processing batches are required to process single crystal silicon rods of the same specification. However, in the process of shouldering, since the speed of the crucible lifting is often a fixed value, the timing of the activation of the crucible lifting affects the timing of shouldering and forking of the single crystal silicon rods, which may easily lead to different forking timings of the same batch of single crystal silicon rods produced by different furnaces during the shouldering and forking process, thereby increasing the risk of inconsistent shoulder shapes of the same batch of single crystal silicon rods, and increasing the risk of inconsistent production data of single crystal silicon rods due to process changes, which is not conducive to the production quality and precision of single crystal silicon rods, and also increases the subsequent shouldering breakage rate of single crystal silicon rods.

[0026] The crucible lifting speed refers to the speed at which the quartz crucible rises. Shoulder breakage is manifested as a broken crystal line, which causes the growth process of the single crystal silicon rod to stop or restart, thereby reducing the production efficiency of the single crystal silicon rod. Forking refers to the process of controlling the change in the growth direction of the single crystal, so that the crystal changes from the initial vertical growth to oblique or horizontal growth. This step is used to improve the quality, precision size, etc. of the single crystal silicon rod.

[0027] The present application provides a method for pulling a single crystal silicon rod, and the method for pulling a single crystal silicon rod comprises the following steps: S1: Put polysilicon into the crucible of the crystal pulling furnace to melt; S2: The seed crystal is fixed on the rotating seed crystal rod, and the seed crystal is rotated and pulled upward to form a single crystal silicon to complete the seeding, and then the shoulder is released; S3: During the shoulder release process, measure the shoulder release diameter d n And shoulder length L n , and the current pulling speed is SL n After t0 time, measure the shoulder diameter d n+1 And shoulder length L n+1 , and the current pulling speed is SL n+1 ; S4: According to the formula Δp=(d n+1 -d n ) / (L n+1 -L n ), calculate the shoulder slope Δp; S5: When the shoulder length is the preset length L, Δp is greater than or equal to the preset slope, or, within t1, Δp increases to the preset slope, it is determined that the single crystal silicon rod is forked; When the shoulder length is the preset length L, if the shoulder slope Δp is less than the preset slope and lasts for t1, it is determined that the single crystal silicon rod is not forked, and the current pulling speed SL is controlled. n+2 <SL n+1 , until Δp is greater than or equal to the preset slope.

[0028] It should be noted that the pulling speed SL is the lifting speed of the single crystal silicon rod, that is, the pulling speed of the furnace.

[0029] In this embodiment, if Figure 2As shown, the shoulder slope Δp value of the single crystal silicon rod is used to determine whether the single crystal silicon rod is forked, so that the pulling speed can be adjusted in time to control the shoulder and fork timing of the single crystal silicon rod, and then the fork timing of the single crystal silicon rods in different furnaces can be adjusted in time. Therefore, the shoulder and fork of the single crystal silicon rod are judged and adjusted to be consistent through the above method, so that the shoulder shape of the single crystal silicon rods processed from different processing batches is consistent, thereby improving the consistency and reproducibility of the single crystal silicon rods of the same specification processed from different processing batches, and making the shapes of the same positions of different single crystal silicon rods consistent, that is, the data uniformity of the single crystal silicon rods of the same specification can be improved, thereby improving the production quality and data accuracy of the single crystal silicon rods. At the same time, in the use of different shoulder release processes, the above method can avoid the risk of reduced production data of single crystal silicon rods due to process changes.

[0030] Among them, when the shoulder length is the preset length L, if the shoulder slope Δp is less than the preset slope and lasts for t1, it is judged that the single crystal silicon rod is not forked, and the current pulling speed SL is controlled n+2 <SL n+1 , until Δp is greater than or equal to the preset slope. In this method, the current pulling speed SL is controlled n+2 <SL n+1 The pulling speed can be controlled by manual operation or other automatic speed control systems.

[0031] At the same time, the crystal pulling method also includes the following steps: S6: After the shoulder is released, the shoulder is rotated and the pulling speed is increased to make the crystal grow longitudinally.

[0032] S7: Equal diameter, reduce the crystal rotation speed, increase the crucible rotation speed, so that the crystal grows at a fixed diameter.

[0033] S8: Finishing to complete the preparation of single crystal silicon rods.

[0034] In a specific embodiment, when shouldering, the speed of the shouldering crucible can be 5rpm, the speed of the shouldering crystal can be 9rpm, the pressure in the crystal pulling furnace is set to 7torr, the argon flow rate can be 90slpm, and the shouldering temperature reduction can be 9kw. When rotating the shoulder, when the diameter of the crystal is 242mm, the shouldering is started, the speed of the shouldering crucible can be 5rpm, the speed of the shouldering crystal can be 9rpm, the pressure in the crystal pulling furnace is set to 7torr, the argon flow rate can be 90slpm, and the shouldering is completed when the diameter of the crystal grows to 260mm.

[0035] When the diameter is equal, the equal-diameter liquid mouth distance can be 18mm, the equal-diameter crystal diameter can be 260mm, the equal-diameter crucible retention rate can be 30%, the equal-diameter crucible speed can be 5rpm-6rpm, the equal-diameter crystal speed can be 9rpm-8rpm, the pressure in the crystal pulling furnace is set to 7torr, and the argon flow rate can be 90slpm.

[0036] In a possible implementation, 50 mm ≤ L ≤ 60 mm, wherein the preset length may be 50 mm, 51 mm, 52 mm, 53 mm, 54 mm, 55 mm, 56 mm, 57 mm, 58 mm, 59 mm, 60 mm, etc.

[0037] In this embodiment, if the preset length is too small, the single crystal silicon rod is shouldered and split in advance, that is, the diameter growth rate of the single crystal silicon rod is too fast at this time, and manual intervention is required to make the shoulder shape of each single crystal silicon rod consistent, which affects the shoulder release survival rate; if the preset length is too large, the single crystal silicon rod is shouldered and split later, that is, the diameter growth rate of the single crystal silicon rod is too slow at this time, and manual intervention is also required to make the shoulder shape of each single crystal silicon rod consistent, which affects the shoulder release survival rate. Therefore, by satisfying 50mm≤L≤60mm, the single crystal silicon rod is automatically split at the preset length L, without the need for operators to intervene in the subsequent process, reducing the dependence on personnel experience and technical level in the shoulder release process, and is conducive to improving the shoulder release survival rate.

[0038] In a possible implementation manner, the preset slope is 1.1.

[0039] In this embodiment, the preset slope is the value of the minimum shoulder split of the single crystal silicon rod. If the preset slope is less than 1.1, that is, when the shoulder length is the preset length L, and the preset slope is less than 1.1, the shoulder splits, because the current diameter growth trend of the single crystal silicon rod is too slow, if the split occurs at this time, it is easy to cause the risk of shoulder breakage, reduce the production quality of the single crystal silicon rod, and also cause the shoulder shape repeatability of the same specification of the single crystal silicon rod processed in different processing batches to be poor, which is not conducive to the data uniformity of the single crystal silicon rod.

[0040] Therefore, the preset slope is 1.1, which can reduce the risk of shoulder breakage of the single crystal silicon rod and ensure that the single crystal silicon rod has better production quality and data accuracy.

[0041] In a possible implementation manner, 0.4s≤t0≤0.6s, and / or, 25s≤t1≤35s.

[0042] Among them, t0 can be 0.4s, 0.45s, 0.5s, 0.55s, 0.6s, etc., and t1 can be 25s, 30s, 35s, etc.

[0043] In this embodiment, t0 is the interval time for measuring the shoulder diameter and shoulder length data. If the measurement interval t0 is too small, there is a risk that the shoulder slope Δp calculated during the shouldering process of the single crystal silicon rod cannot always be greater than the preset slope, resulting in the risk of being unable to judge the timing of shouldering forking; if the measurement interval t0 is too large, there is a risk that the changes in the shoulder diameter and shoulder length cannot be measured in time, resulting in the risk of missing the opportunity to judge the shouldering forking, increasing the risk of inconsistent shoulder shapes of single crystal silicon rods in different processing batches. Therefore, satisfying 0.3s≤t0≤0.6s is conducive to improving the timeliness and accuracy of the crystal pulling method for judging whether the single crystal silicon rod is forked, and is also conducive to improving the reliability of producing single crystal silicon rods with consistent shoulder shapes.

[0044] In this embodiment, t1 is the waiting time for judging the fluctuation of the shoulder release slope. Since the shoulder release slope Δp is a fluctuating value during the shoulder release process, the waiting time t1 is preset to increase the accuracy of judging whether the single crystal silicon rod is currently shouldered and split. If t1 is too small, that is, the waiting time is too short, there is a risk that the single crystal silicon rod may split in a short period of time and it is judged that it is not currently split, and then the pulling speed is reduced, causing the shoulder release diameter to grow too fast, resulting in a greatly increased shoulder release wire breakage rate; if t1 is too large, that is, the waiting time is too long, it is easy to miss the opportunity to adjust the pulling speed, and then miss the opportunity to split, which is easy to cause the risk of inconsistent splitting time of single crystal silicon rods in different boilers, and then the risk of inconsistent shoulder shape. Therefore, satisfying 25s≤t1≤35s is conducive to improving the accuracy of the method for judging whether the single crystal silicon rod is split, and at the same time is conducive to improving the reliability of producing single crystal silicon rods with consistent shoulder shape.

[0045] In a possible implementation manner, during the shoulder release process, the real-time crucible lifting speed CL satisfies:

[0046] Where D is the inner diameter of the crucible, d is the current shoulder diameter, and SL is the current pulling speed.

[0047] In this embodiment, during the shoulder release process, the crystal pulling method may further include: Real-time measurement of the current shoulder diameter and current pulling speed, and according to the formula:

[0048] The value CL that the real-time crucible lifting speed should meet is calculated, and the actual crucible lifting speed is adjusted to the calculated CL value, so that during the shouldering process, the crucible lifting speed can be adjusted in real time according to the current shouldering diameter and the current pulling speed, reducing the risk of mismatch between the crucible lifting speed and the current shouldering diameter and the current pulling speed, thereby reducing the shouldering wire breakage rate. At the same time, during the shouldering process, there is no need for personnel to manually adjust the crucible lifting speed, reducing the dependence on personnel experience and technical level during the shouldering process, and improving the shouldering survival rate.

[0049] It should be noted that It is the crucible-to-heel ratio. During the shoulder releasing process, as the current shoulder releasing diameter increases, the crucible-to-heel ratio gradually increases, and then the crucible lifting speed is adjusted in real time to meet the crucible lifting requirements required in the shoulder releasing process.

[0050] In a possible implementation manner, during the shoulder release process, the crystal pulling method further includes: The actual pulling speed of the single crystal silicon rod is adjusted by a proportional integral derivative (PID) control system so that the real-time crucible lifting speed CL matches the current pulling speed SL of the single crystal silicon rod.

[0051] In this embodiment, after adjusting the real-time crucible lifting speed CL by the actual diameter d, after a short period of time, the pulling speed is adjusted again by the real-time crucible lifting speed CL and the actual diameter d through the PID system, that is, the real-time crucible lifting speed CL is adjusted by the actual diameter d and the current pulling speed SL, and at the same time, the real-time crucible lifting speed CL and the actual diameter d can in turn adjust the current pulling speed SL, so that in the shouldering process, the data of the actual diameter d, the current pulling speed SL and the real-time crucible lifting speed CL affect each other and can be adjusted to a state of dynamic equilibrium, so that the real-time crucible lifting speed CL and the actual diameter d can match the current pulling speed SL of the single crystal silicon rod. Therefore, since the shouldering diameter is gradually increased, and the crucible heel ratio is also gradually increased, the crucible lifting speed changes slowly with the crucible heel ratio, and the crucible lifting speed fluctuates less, which helps to reduce the fluctuation of the pulling speed and make the pulling speed change smoothly, thereby providing a more stable shouldering environment and further reducing the shouldering wire breakage rate.

[0052] also, Figure 3 The variation of pulling speed shown is relative to Figure 4 The variation of the drawing speed shown is small, that is, the drawing speed adjusted by the above method has a small fluctuation, thereby reducing the shoulder breakage rate. Figure 3 and Figure 4 The middle horizontal axis is marked with the actual length L of the single crystal silicon rod. Since the actual length L and the actual diameter change at the same time, the change in the actual length L can also reflect the change in the actual diameter length d of the single crystal silicon rod, and then the change in pulling speed can be reflected by the actual length L and the actual pulling speed SL.

[0053] In a possible implementation, adjusting the actual pulling speed of the single crystal silicon rod by a proportional-integral-differential control system includes the following steps: Calculate the difference between the current shoulder diameter slope and the basic shoulder diameter slope.

[0054] If the difference between the current shoulder diameter slope and the basic shoulder diameter slope is less than a preset value, the proportional integral differential control system controls the current pulling speed of the single crystal silicon rod to increase, and the current pulling speed is the pulling speed corresponding to the current shoulder slope.

[0055] If the difference between the current shoulder diameter slope and the basic shoulder diameter slope is greater than a preset value, the proportional integral differential control system controls the current pulling speed of the single crystal silicon rod to decrease, and the current pulling speed is the pulling speed corresponding to the current shoulder slope.

[0056] In this embodiment, the shouldering diameter slope is measured by the PID system, and the difference between the current shouldering diameter slope and the basic shouldering diameter slope is compared with the preset value, and then the pulling speed is adjusted to make the current pulling speed the pulling speed corresponding to the current shouldering slope, that is, the current shouldering diameter is matched with the current pulling speed, and then the current crucible heel ratio is matched with the current pulling speed, and then the crucible lifting speed is matched with the current pulling speed. Through the above method, during the shouldering process, there is no need for personnel to adjust the pulling speed, which is easy to operate.

[0057] Among them, in this embodiment, the preset value is related to the specifications of the machine executing the PID system. This application does not specifically limit this value, as long as the PID system controls the current pulling speed to the pulling speed corresponding to the current shoulder slope through the above method.

[0058] In summary, as shown in the following Table 1, Table 1 is the actual simulation quantity in the shouldering process of the single crystal silicon rod in the same experiment.

[0059] Specifically, in a specific embodiment, the actual length of the single crystal silicon rod is 10 mm, the actual shoulder diameter is 12.6 mm, the actual shoulder cooling amount is -1.5 kw, the simulated crucible toe ratio is about 0.0002, the actual pulling speed SL is about 55 mm / hr, and the actual crucible lifting speed CL is about 0.01 mm / hr. Subsequently, the single crystal silicon rod grows to an actual length of 20 mm, an actual shoulder diameter of 18.0 mm, an actual shoulder cooling amount is -1.9 kw, the simulated crucible toe ratio is about 0.0004, the actual pulling speed SL is about 56 mm / hr, and the actual crucible lifting speed CL is about 0.02 mm / hr. Subsequently, the single crystal silicon rod continues to grow to an actual length of 40 mm, an actual shoulder diameter of 29.4 mm, an actual shoulder cooling amount is -2.5 kw, the simulated crucible toe ratio is about 0.0010, the actual pulling speed SL is about 58 mm / hr, and the actual crucible lifting speed CL is about 0.06 mm / hr. Then the single crystal silicon rod continued to grow to an actual length of 55mm, an actual shoulder diameter of 45.9mm, an actual shoulder cooling amount of -3.3kw, a simulated crucible to heel ratio of about 0.0023, an actual pulling speed SL of about 58mm / hr, and an actual crucible lifting speed CL of about 0.13mm / hr. Then the single crystal silicon rod continued to grow to an actual length of 60mm, an actual shoulder diameter of 46.7mm, an actual shoulder cooling amount of -3.5kw, a simulated crucible to heel ratio of about 0.0024, an actual pulling speed SL of about 60mm / hr, and an actual crucible lifting speed CL of about 0.14mm / hr. Then the single crystal silicon rod continued to grow to an actual length of 80mm, an actual shoulder diameter of 65.5mm, an actual shoulder cooling amount of -4.5kw, a simulated crucible to heel ratio of about 0.0047, an actual pulling speed SL of about 53mm / hr, and an actual crucible lifting speed CL of about 0.25mm / hr. Then the single crystal silicon rod continued to grow to an actual length of 90mm, an actual shoulder diameter of 88.2mm, an actual shoulder cooling amount of -5.7kw, a simulated crucible to heel ratio of about 0.0086, an actual pulling speed SL of about 55mm / hr, and an actual crucible lifting speed CL of about 0.47mm / hr. Then the single crystal silicon rod continued to grow to an actual length of 100mm, an actual shoulder diameter of 103.5mm, an actual shoulder cooling amount of -6.9kw, a simulated crucible to heel ratio of about 0.0118, an actual pulling speed SL of about 62mm / hr, and an actual crucible lifting speed CL of about 0.73mm / hr. Then the single crystal silicon rod continued to grow to an actual length of 110mm, an actual shoulder diameter of 118.6mm, an actual shoulder cooling amount of -7.5kw, a simulated crucible to heel ratio of about 0.0155, an actual pulling speed SL of about 65mm / hr, and an actual crucible lifting speed CL of about 1.01mm / hr.Then the single crystal silicon rod continued to grow to an actual length of 120mm, an actual shoulder diameter of 134.0mm, an actual shoulder cooling amount of -8.3kw, a simulated crucible to heel ratio of about 0.0198, an actual pulling speed SL of about 63mm / hr, and an actual crucible lifting speed CL of about 1.25mm / hr. Then the single crystal silicon rod continued to grow to an actual length of 130mm, an actual shoulder diameter of 164.2mm, an actual shoulder cooling amount of -9kw, a simulated crucible to heel ratio of about 0.0297, an actual pulling speed SL of about 68mm / hr, and an actual crucible lifting speed CL of about 2.02mm / hr. Then the single crystal silicon rod continued to grow to an actual length of 140mm, an actual shoulder diameter of 189.5mm, an actual shoulder cooling amount of -9kw, a simulated crucible to heel ratio of about 0.0396, an actual pulling speed SL of about 65mm / hr, and an actual crucible lifting speed CL of about 2.57mm / hr. Then the single crystal silicon rod continued to grow to an actual length of 150mm, an actual shoulder diameter of 215.3mm, an actual shoulder cooling amount of -9kw, a simulated crucible to heel ratio of about 0.0511, an actual pulling speed SL of about 58mm / hr, and an actual crucible lifting speed CL of about 2.96mm / hr. Then the single crystal silicon rod continued to grow to an actual length of 160mm, an actual shoulder diameter of 242.2mm, an actual shoulder cooling amount of -9kw, a simulated crucible to heel ratio of about 0.0647, an actual pulling speed SL of about 62mm / hr, and an actual crucible lifting speed CL of about 4.01mm / hr.

[0060]

[0061] Table 1 In a possible implementation, as shown in the simulated data in Table 1 above, when the shoulder length is the preset length L and equal to 55 mm, the actual shoulder diameter is 45.9 mm, the simulated crucible heel ratio is 0.0023, the actual pulling speed is 58 mm / hr, and the actual crucible lifting speed is 0.13 mm / hr.

[0062] In this embodiment, when the shoulder length is the preset length L and is equal to 55 mm, according to the formula Δp=(d n+1 -d n ) / (L n+1 -L n ), the shoulder slope Δp is calculated to be 1.1, and it is judged that the shoulder of the single crystal silicon rod is split, and the split can improve the shoulder survival rate when the shoulder length is 55mm. In addition, during the shoulder release process, the speed of the crucible is adjusted in real time, even if the speed of the crucible is sufficient to meet the current shoulder release diameter, and the speed of the crucible during the process fluctuates less, further reducing the risk of shoulder breakage.

[0063] In a possible implementation, the size of the single crystal silicon rod is 10 inches, the distance between the lead and discharge liquids is M, which satisfies 30mm≤M≤32mm, and the average pulling speed of the seeding is V, which satisfies 260mm / hr≤V≤300mm / hr. Among them, the distance between the lead and discharge liquids, M, can be 30mm, 30.5mm, 31mm, 31.5mm, 32mm, and the average pulling speed V of the seeding can be 260mm / hr, 265mm / hr, 270mm / hr, 275mm / hr, 280mm / hr, 285mm / hr, 290mm / hr, 295mm / hr, 300mm / hr, etc.

[0064] In this embodiment, when the distance M between the liquid outlet and the discharge port is too large or too small, it is not conducive to accurately controlling the growth rate of the crystal, resulting in the risk of large diameter fluctuations or abnormal shapes of the single crystal silicon rod, reducing the survival rate of the shoulder release, and also increasing the risk of defects in the single crystal silicon rod, such as dislocations, micropipes or impurity segregation, reducing production quality. Therefore, satisfying 30mm≤M≤32mm is conducive to accurately controlling the change of the shoulder release slope, so as to improve the survival rate of the shoulder release and improve the production quality of the single crystal silicon rod.

[0065] If the average seeding speed V is too large or too small, the rapid growth rate of the single crystal silicon rod will be too fast or too slow, which is not conducive to the precise control of the diameter of the single crystal silicon rod, and also leads to the risk of diameter fluctuation or irregular shape, reducing the survival rate of shoulder release. Therefore, meeting 260mm / hr≤V≤300mm / hr is conducive to the precise control of the change of the shoulder release slope to improve the survival rate of the shoulder release.

[0066] Among them, the liquid mouth distance is the vertical distance between the heat conduction tube in the crystal pulling furnace and the liquid surface of the melt in the crystal pulling furnace.

[0067] The present application also provides a single crystal silicon rod, which is prepared by the crystal pulling method for the single crystal silicon rod in any of the above embodiments.

[0068] In this embodiment, whether the single crystal silicon rod is forked is judged by the shoulder slope Δp value of the single crystal silicon rod, so that the pulling speed can be adjusted in time to control the timing of shouldering and forking of the single crystal silicon rod, and then the forking timing of the single crystal silicon rods in different furnaces can be adjusted, and the above method is used to further judge and adjust so that the shoulder shape of the single crystal silicon rods processed by different processing batches remains consistent, thereby improving the consistency and reproducibility of single crystal silicon rods of the same specification processed by different processing batches, and making the shapes of the same positions of different single crystal silicon rods consistent, that is, the data uniformity of single crystal silicon rods of the same specification can be improved, thereby improving the production quality and data accuracy of single crystal silicon rods.

[0069] The above is only a specific implementation of the embodiment of the present application, but the protection scope of the embodiment of the present application is not limited thereto, and any changes or replacements within the technical scope disclosed in the embodiment of the present application should be included in the protection scope of the embodiment of the present application. Therefore, the protection scope of the embodiment of the present application should be based on the protection scope of the claims.

Claims

1. A method for pulling a single crystal silicon rod, characterized in that: The method for pulling a single crystal silicon rod comprises the following steps: Put polysilicon into the crucible of the crystal pulling furnace to melt; The seed crystal is rotated and pulled upward to complete the seeding and shoulder release; During the shoulder release process, measure the shoulder release diameter d n And shoulder length L n , and the current pulling speed is SL n After t0 time, measure the shoulder diameter d n+1 And shoulder length L n+1 , and the current pulling speed is SL n+1 ; According to the formula Δp=(d n+1 -d n ) / (L n+1 -L n ), calculate the shoulder slope Δp; When the shoulder length is the preset length L, Δp is greater than or equal to the preset slope, or, within t1, Δp increases to the preset slope, it is determined that the single crystal silicon rod is forked; When the shoulder length is the preset length L, if the shoulder slope Δp is less than the preset slope and lasts for t1, it is determined that the single crystal silicon rod is not forked, and the current pulling speed SL is controlled. n+2 <SL n+1 , until Δp is greater than or equal to the preset slope.

2. The method for pulling a single crystal silicon rod according to claim 1, characterized in that: 50mm≤L≤60mm.

3. The method for pulling a single crystal silicon rod according to claim 1, characterized in that: The default slope is 1.

1.

4. The method for pulling a single crystal silicon rod according to claim 1, characterized in that: 0.4s≤t0≤0.6s, and / or, 25s≤t1≤35s.

5. The method for pulling a single crystal silicon rod according to claim 1, characterized in that: During the shoulder release process, the real-time crucible lifting speed CL satisfies: Where D is the inner diameter of the crucible, d is the current shoulder diameter, and SL is the current pulling speed.

6. The method for pulling a single crystal silicon rod according to claim 1, characterized in that: When the shoulder length is the preset length L and equal to 55 mm, the actual shoulder diameter is 45.9 mm, the simulated crucible heel ratio is 0.0023, the actual crucible lifting speed is 0.13 mm / hr, and the actual pulling speed is 58 mm / hr.

7. The method for pulling a single crystal silicon rod according to any one of claims 1 to 6, characterized in that: During the shoulder release process, the crystal pulling method further includes: The actual pulling speed of the single crystal silicon rod is adjusted by a proportional-integral-differential control system so that the real-time crucible lifting speed CL matches the current pulling speed SL of the single crystal silicon rod.

8. The method for pulling a single crystal silicon rod according to claim 7, characterized in that: Adjusting the actual pulling speed of the single crystal silicon rod by the proportional integral derivative control system includes the following steps: Calculate the difference between the current shoulder diameter slope and the basic shoulder diameter slope; If the difference between the current shoulder diameter slope and the basic shoulder diameter slope is less than a preset value, the proportional integral differential control system controls the current pulling speed of the single crystal silicon rod to increase, and the current pulling speed is the pulling speed corresponding to the current shoulder slope; If the difference between the current shoulder diameter slope and the basic shoulder diameter slope is greater than a preset value, the proportional integral differential control system controls the current pulling speed of the single crystal silicon rod to decrease, and the current pulling speed is the pulling speed corresponding to the current shoulder slope.

9. The method for pulling a single crystal silicon rod according to any one of claims 1 to 6, characterized in that: The distance between the liquid inlet and outlet is M, which satisfies 30mm≤M≤32mm; the average pulling speed of the crystal is V, which satisfies 260mm / hr≤V≤300mm / hr.

10. A single crystal silicon rod, characterized in that: The single crystal silicon rod is prepared by the single crystal silicon rod pulling method according to any one of claims 1 to 9.

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