Manufacturing method for monocrystalline silicon ingot, and monocrystalline silicon ingot

Abstract

Disclosed in the present disclosure are a manufacturing method for a monocrystalline silicon ingot, and a monocrystalline silicon ingot. The manufacturing method may comprise: selecting a preset position of a target monocrystalline silicon ingot, wherein a first distance from the preset position to the head portion of the monocrystalline silicon ingot is n times a machining length of a wire cutting machine, and a second distance from the preset position to the tail portion of the monocrystalline silicon ingot is m times the machining length of the wire cutting machine, n and m being positive integers; determining a target resistivity at the preset position, calculating a doping amount of a dopant for a silicon melt on the basis of the target resistivity, adding the dopant to the silicon melt on the basis of the calculated doping amount of the dopant, and pulling a target monocrystalline silicon ingot by using the Czochralski process; and cutting the target monocrystalline silicon ingot at the preset position, the silicon ingot segment between the head portion of the target monocrystalline silicon ingot and the preset position being used for preparing a first battery product, and the silicon ingot segment between the preset position and the tail portion of the target monocrystalline silicon ingot being used for preparing a second battery product. The present solution can effectively improve the yield of manufactured monocrystalline silicon ingots, and prevent the problem of waste when monocrystalline silicon ingots are cut.

Description

Method for preparing single crystal silicon rod and single crystal silicon rod

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese patent application No. 202411237656.5, filed on September 4, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to a method for preparing a single crystal silicon rod and a single crystal silicon rod. BACKGROUND

[0004] For the technology of drawing a single crystal silicon rod by using the Czochralski method (also known as the direct pulling single crystal method), the amount of dopant in the silicon solution affects the resistivity of the single crystal silicon rod. Based on this, at present, the amount of dopant in the silicon solution is mainly regulated by detecting the resistivity of the head of the single crystal silicon rod, in order to achieve the purpose of regulating the resistivity of the single crystal silicon rod.

[0005] However, due to the relatively high oxygen content in the head of the single crystal silicon rod, the detected resistivity of the single crystal silicon rod is relatively low, which causes a relatively large deviation in regulating the amount of dopant in the silicon solution based on the detected resistivity, resulting in that only part of the segments of the drawn single crystal silicon rod can meet the product requirements, and the yield of the single crystal silicon rod is relatively low, causing a relatively large loss. In addition, at present, the cutting line of the silicon rod segment is determined based on the resistivity of the single crystal silicon rod, and the silicon rod segment cut based on the cutting line often needs to be further cut or multiple silicon rod segments need to be spliced, in order to meet the processing requirements of the cutting machine, resulting in a low cutting efficiency of the single crystal silicon rod.

[0006] SUMMARY

[0007] Therefore, the present disclosure provides a method for preparing a single crystal silicon rod and a single crystal silicon rod, which can effectively improve the yield of the produced single crystal silicon rod and avoid the problem of waste in cutting the single crystal silicon rod.

[0008] To solve the above technical problems, the present disclosure provides the following technical solutions:

[0009] In a first aspect, the present disclosure provides a method for preparing a single crystal silicon rod, comprising:

[0010] Step 1, selecting a preset position of a target single crystal silicon rod, wherein a first distance from the preset position to the head of the single crystal silicon rod is n times of the processing length of a wire cutting machine, and a second distance from the preset position to the tail of the single crystal silicon rod is m times of the processing length of the wire cutting machine, wherein n and m are positive integers;

[0011] Step 2, determining a target resistivity at the preset position, calculating a doping amount of the dopant in the silicon solution according to the target resistivity at the preset position, and adding the dopant to the silicon solution according to the calculated doping amount of the dopant, and then drawing a target single crystal silicon rod by using a Czochralski method;

[0012] Step 3, cutting the target single crystal silicon rod at the preset position, wherein a rod segment between a head of the target single crystal silicon rod and the preset position is used to prepare a first battery product, and a rod segment between the preset position and a tail of the target single crystal silicon rod is used to prepare a second battery product.

[0013] In a second aspect, the embodiments of the present disclosure provide a single crystal silicon rod prepared based on the method for preparing a single crystal silicon rod provided in the first aspect.

[0014] The technical solution of the first aspect of the above disclosure has the following advantages or beneficial effects:

[0015] The technical solution provided in the embodiments of the present disclosure selects a preset position of a target single crystal silicon rod, determines a target resistivity at the preset position, calculates a doping amount of a dopant in a silicon solution according to the target resistivity at the preset position, and can reduce the influence of high oxygen content in the head of the single crystal silicon rod on the detection result of the resistivity, improve the accuracy of the resistivity regulation of the drawn target single crystal silicon rod, and effectively improve the yield of the produced single crystal silicon rod.

[0016] In addition, compared with the prior art that only regulates the doping amount of the dopant according to the resistivity of the head of the single crystal silicon rod, resulting in the uncertainty of the segmentation line that meets the first battery product and meets the second battery product (which makes the length of the single crystal silicon rod after cutting not match the processing length of the cutting machine, not only affecting the processing efficiency of the wire cutting machine, but also easily causing the waste of single crystal silicon), the present technical solution cuts the single crystal silicon rod at the preset position, the rod segment between the head of the target single crystal silicon rod and the preset position is used to prepare the first battery product, and the rod segment between the preset position and the tail of the target single crystal silicon rod is used to prepare the second battery product, which not only makes the resistivity of the target single crystal silicon rod meet the needs of the two battery products, but also makes the first distance from the preset position to the head of the single crystal silicon rod and the second distance from the preset position to the tail of the single crystal silicon rod both meet the processing length of the wire cutting machine, so that the segmentation position of the single crystal silicon rod that meets the first battery product and meets the second battery product is located at the preset position, and the two segments of the single crystal silicon rod after cutting both exactly meet the processing length of the cutting machine, which can reduce or even avoid the waste of single crystal silicon, improve the utilization rate of the single crystal silicon rod, and improve the processing efficiency of the wire cutting machine. BRIEF DESCRIPTION OF DRAWINGS

[0017] FIG. 1 is a main flowchart of a method for preparing a single crystal silicon rod according to an embodiment of the present disclosure;

[0018] FIG. 2 is a schematic diagram of a cross-sectional structure of a single crystal silicon rod according to an embodiment of the present disclosure;

[0019] FIG. 3 is a main flowchart of a method for adjusting the resistivity of a single crystal silicon rod according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0020] As described in the background, for a single crystal silicon rod drawn by the Czochralski method, the resistivity of the head of the single crystal silicon rod is generally detected, and the doping amount of the silicon solution is adjusted, which can cause the resistivity of the single crystal silicon rod to be too low. In addition, the resistivity of the single crystal silicon rod drawn by the Czochralski method has a certain trend in the axial direction (i.e., the resistivity decreases from the head to the tail of the single crystal silicon rod), and the low resistivity superimposes the distribution trend of the resistivity in the axial direction. Therefore, when the single crystal silicon rod is cut by the current conventional process (a single crystal silicon rod is only cut into one type of silicon wafer, which is applied to one type of battery product), the silicon rod segment whose resistivity does not meet the product requirements needs to be removed, such as removing the head or tail of the single crystal silicon rod, which causes waste of the single crystal silicon rod. For example, the current various types of batteries such as TOPCON batteries, BC batteries, HJT batteries, etc. have different requirements for the resistivity, oxygen content, and minority carrier lifetime of silicon wafers. For example, the TOPCON battery is a high-temperature process, and the high-oxygen portion of the silicon wafer is prone to form concentric circles during the high-temperature process, thereby affecting the battery efficiency. Therefore, the TOPCON battery has a significantly lower requirement for the resistivity and oxygen content of the silicon wafer. A normal TOPCON single crystal silicon rod needs to have the head portion with high resistivity and high oxygen content removed directly, and the removed portion is treated as raw material for re-drawing a single crystal, which causes waste of the drawn crystal product and increases the production cost of the drawn crystal.

[0021] Although in order to improve the utilization rate of the single crystal silicon rod, the current process cuts a single crystal silicon rod into silicon rod segments that meet the requirements of two types of battery products, but the scheme of adjusting the doping amount of the dopant according to the resistivity of the head of the single crystal silicon rod leads to uncertainty of the division line that meets the requirements of the first battery product and the second battery product (the scheme makes the length of the single crystal silicon rod after cutting not match the processing length of the cutting machine, which not only affects the processing efficiency of the wire cutting machine, but also easily causes waste of the single crystal silicon), which leads to low cutting efficiency and still cannot avoid the problem of waste of the single crystal silicon rod.

[0022] To solve the above problems in the prior art, the present disclosure provides a single crystal silicon rod preparation method and a single crystal silicon rod. The single crystal silicon rod preparation method can draw a single crystal silicon rod that meets the needs of two battery products, and the cut silicon rod segment meets the processing needs of the two battery products, to solve the problems of low yield of drawn single crystal silicon rods, cutting waste, low cutting efficiency, and high crystal pulling production cost.

[0023] Specifically, as shown in FIG. 1, the single crystal silicon rod preparation method provided by the present disclosure can include the following steps:

[0024] Step S101: selecting a preset position of a target single crystal silicon rod, wherein a first distance from the preset position to a head of the single crystal silicon rod is n times the processing length of a wire cutting machine, and a second distance from the preset position to a tail of the single crystal silicon rod is m times the processing length of the wire cutting machine, wherein n and m are positive integers;

[0025] The target single crystal silicon rod generally refers to a silicon rod segment from the starting position to the end position of the isodiametric growth of the single crystal silicon rod, which is generally used to cut into two segments to meet the needs of two battery products.

[0026] As shown in FIG. 2, the single crystal silicon rod, wherein the head H of the single crystal silicon rod generally refers to the starting position of the isodiametric growth of the single crystal silicon rod; the tail T of the single crystal silicon rod generally refers to the end position of the isodiametric growth of the single crystal silicon rod, that is, the diameter of the head H of the single crystal silicon rod is generally equal to or close to the diameter of the tail T of the single crystal silicon rod. The distance from the head H of the single crystal silicon rod to the tail T of the single crystal silicon rod is an integer multiple of the processing length of the wire cutting machine. The target single crystal silicon rod is between the head H of the single crystal silicon rod and the tail T of the single crystal silicon rod.

[0027] The preset position of the target single crystal silicon rod refers to the position of the cutting line for cutting the single crystal silicon rod into two segments. In the axial direction of the target single crystal silicon rod, the first distance from the preset position of the target single crystal silicon rod to the head of the single crystal silicon rod is n times the processing length of the wire cutting machine, and the first distance is generally a fixed value; in the axial direction of the target single crystal silicon rod, the second distance from the preset position of the target single crystal silicon rod to the tail of the single crystal silicon rod is m times the processing length of the wire cutting machine, and the second distance is also generally a fixed value, wherein n and m are positive integers, n can be equal to m, and n can also not be equal to m. That is, the circumferential position of the preset position is relatively fixed relative to the head of the single crystal silicon rod and / or the tail of the single crystal silicon rod. The first distance and the second distance can meet the size requirements of the battery products, and the utilization rate of the single crystal silicon rod can be further improved during the processing of the single crystal silicon rod, and the waste of the single crystal silicon rod can be reduced.

[0028] For example, the target single crystal silicon rod shown in FIG. 2, the preset position of this step can be any one or more positions on the circumference corresponding to P1 as identified in FIG. 2, or any one or more positions on the circumference corresponding to P2 as identified in FIG. 2, but after being selected in step S101, the preset position becomes a fixed position. For the case where any one or more positions on the circumference corresponding to P1 as identified in FIG. 2 is the preset position, the first distance is x1 as identified in FIG. 2, and the second distance is y1 as identified in FIG. 2; for the case where any one or more positions on the circumference corresponding to P2 as identified in FIG. 2 is the preset position, the first distance is x2 as identified in FIG. 2, and the second distance is y2 as identified in FIG. 2.

[0029] In addition, for the above-mentioned preset position, in addition to the first distance and the second distance both satisfying the processing length of the wire cutting machine (i.e. the first distance from the preset position to the head of the single crystal silicon rod is n times the processing length of the wire cutting machine, and the second distance from the preset position to the tail of the single crystal silicon rod is m times the processing length of the wire cutting machine, where n and m are positive integers), preferably, the preset position selected in step S101 can be further selected based on at least one of the following two conditions:

[0030] Condition 1: the oxygen content of the target single crystal silicon rod at the preset position is less than or equal to 5.5 x 10 17 atoms / cm 3 ;

[0031] Condition 2: the pulling speed at the preset position during the pulling of the target single crystal silicon rod is greater than or equal to 1.5 mm / min.

[0032] More preferably, the first distance from the preset position to the head of the single crystal silicon rod is n times the processing length of the wire cutting machine, and the second distance from the preset position to the tail of the single crystal silicon rod is m times the processing length of the wire cutting machine, and at the same time, the preset position also satisfies the above two conditions.

[0033] It is found through research that the oxygen content at the detection position affects the accuracy of the detection result. Specifically, the resistivity detection currently relies on the doping concentration or amount of metal-doped elements, that is, the resistivity is affected by the doping concentration or amount of metal-doped elements. As a donor, one oxygen atom can provide two electrons, and the electrons can affect the true doping concentration or true amount of metal-doped elements, thereby affecting the accuracy of the detection. The higher the oxygen content, the greater the impact on the detection (specifically, it can make the detected resistivity of the P-type single crystal silicon rod too high and the detected resistivity of the N-type single crystal silicon rod too low). In the axial direction of the single crystal silicon rod, the oxygen content decreases from the head of the single crystal silicon rod to the tail of the single crystal silicon rod, and when the oxygen content decreases to a certain extent, the oxygen content no longer shows a significant change trend. It is found through further research that when the oxygen content is less than or equal to 5.5 x 1017 atoms / cm 3 Afterwards, oxygen has a relatively small impact on the accuracy of the detection results. Based on this, in the process of selecting the preset position in step S101 above, while ensuring that the first distance from the preset position to the head of the monocrystalline silicon rod is n times the processing length of the wire cutting machine, and the second distance from the preset position to the tail of the monocrystalline silicon rod is m times the processing length of the wire cutting machine, priority is given to selecting an oxygen content less than or equal to 5.5 × 10⁻⁶. 17 atoms / cm 3 The location.

[0034] Generally, increasing the pulling speed corresponds to a decrease in solution temperature, which in turn indicates a reduction in oxygen content. During the single-crystal silicon rod pulling process, in the constant diameter stage, the initial pulling speed is initially increased from 1.0 to 1.3 mm / min. For lengths exceeding 300 mm, the average pulling speed per 100 mm (from this position to the first 100 mm) can reach 1.5 mm / min or higher. Field measurements show that the accuracy of resistivity tests improves when the average pulling speed per 100 mm is greater than or equal to 1.5 mm / min. Based on this, and ensuring that the first distance from the preset position to the head of the single-crystal silicon rod is n times the processing length of the wire EDM machine, and the second distance from the preset position to the tail of the single-crystal silicon rod is m times the processing length of the wire EDM machine, the position with a pulling speed greater than or equal to 1.5 mm / min is preferentially selected as the aforementioned preset position.

[0035] Furthermore, the target resistivity at the preset position satisfies the following: the resistivity of the silicon rod segment from the preset position to the head of the monocrystalline silicon rod satisfies the requirements of the first battery product, and the resistivity of the silicon rod segment from the preset position to the tail of the monocrystalline silicon rod satisfies the requirements of the second battery product.

[0036] For the target single-crystal silicon rod in this step, the silicon solution used in the pulling process can contain only one type of dopant or multiple dopants. The doping elements contained in one or more dopants are generally the same; for example, they can be N-type dopants (such as dopants containing phosphorus) or P-type dopants (such as dopants containing boron).

[0037] Step S102: Determine the target resistivity at the preset position, calculate the doping amount of the dopant in the silicon solution based on the target resistivity at the preset position, add the dopant to the silicon solution based on the calculated doping amount, and then pull the target single crystal silicon rod using the Czochralski method.

[0038] The target resistivity of the preset position can be determined according to the requirements of the two battery products, and the target resistivity can be a preset range, which can allow a certain adjustment error of the target single crystal silicon rod, reduce the adjustment difficulty, and ensure the yield of the target single crystal silicon rod. The specific implementation process of this step will be described in detail below, and will not be repeated here.

[0039] Step S103: cutting the target single crystal silicon rod at the preset position, wherein the silicon rod segment between the head of the target single crystal silicon rod and the preset position is used to prepare the first battery product, and the silicon rod segment between the preset position and the tail of the target single crystal silicon rod is used to prepare the second battery product.

[0040] Generally, there is also an overlapping interval between the first resistivity control range of the silicon wafer required by the first battery product and the second resistivity control range of the silicon wafer required by the second battery product, and the target resistivity of the preset position of the target single crystal silicon rod is within the overlapping interval. By limiting the target resistivity of the preset position to be within the overlapping interval between the first resistivity control range and the second resistivity control range, the preset position can be selected within a range, ensuring that the preset position has certain selection flexibility, and the resistivity of the drawn single crystal silicon rod can fluctuate within the resistivity control range, reducing the process precision of the single crystal silicon rod drawing process, improving the single crystal silicon rod yield, and enabling the preset position to be used as a cutting line for cutting the single crystal silicon rod, while meeting the first battery product and the second battery product, without single crystal silicon regions that do not meet the battery product, effectively improving the utilization rate of the single crystal silicon rod.

[0041] It is worth noting that the selection of the first battery product and the second battery product of the embodiments of the present disclosure is based on experience, market demand, process demand, etc., and only needs to ensure that there is an overlapping interval between the first resistivity control range of the silicon wafer required by the first battery product and the second resistivity control range of the silicon wafer required by the second battery product, in order to ensure the utilization rate of the single crystal silicon rod. Accordingly, after the target single crystal silicon rod resistivity does not meet the requirements, the target single crystal silicon rod resistivity can be adjusted based on the above step S102.

[0042] In addition, the first battery product can be determined first, the head of the target monocrystalline silicon rod is made to meet the first battery product, and the second battery product is selected according to the distribution of the doping concentration in the axial direction of the target monocrystalline silicon rod. That is, the second battery product can also be selected based on the first battery product and the distribution of the resistivity of the target monocrystalline silicon rod meeting the first battery product in the axial direction. After the first battery product and the second battery product are determined, the doping amount of the target monocrystalline silicon rod is controlled based on the above steps S101 to S102 to achieve the purpose of controlling the resistivity of the target monocrystalline silicon rod, and the silicon rod segments required for the first battery product and the silicon rod segments required for the second battery product are prepared through the above step S103, so as to ensure the utilization rate of the monocrystalline silicon rod.

[0043] The first battery product and the second battery product provided by the technical scheme of the embodiments of the present disclosure are not simply obtained by the user according to the demand freely or arbitrarily, but are combined with the distribution of the resistivity or the doping concentration of the target monocrystalline silicon rod in the axial direction, so that the selected battery product is more suitable for the target monocrystalline silicon rod, and the cutting waste of the monocrystalline silicon rod is further reduced. And based on the first battery product and the distribution of the doping concentration in the axial direction of the target monocrystalline silicon rod, the second battery product is determined, which can adapt the crystal growth process to the target monocrystalline silicon rod growth, improve the crystal growth rate, improve the yield, and further improve the yield and reduce the production cost.

[0044] Therefore, by detecting the resistivity of the preset position, and subsequently regulating the doping amount of the dopant in the silicon solution based on the detected resistivity of the preset position, compared with the prior art of detecting the resistivity of the head of the monocrystalline silicon rod and regulating the doping amount of the dopant in the silicon solution based on the resistivity of the head, the influence of the high oxygen content of the head of the monocrystalline silicon rod on the detection result of the resistivity can be reduced, the accuracy of the resistivity regulation of the drawn target monocrystalline silicon rod can be improved, and the yield of the produced monocrystalline silicon rod can be effectively improved.

[0045] In addition, compared with the prior art which only adjusts the doping amount of the dopant according to the resistivity of the head of the single crystal silicon rod to cause the split line between the first battery product and the second battery product to have uncertainty (which causes the length of the single crystal silicon rod after cutting to be inconsistent with the processing length of the cutting machine, thereby affecting the processing efficiency of the wire cutting machine and easily causing waste of the single crystal silicon), the technical solution cuts the single crystal silicon rod at the preset position, and the rod segment between the head of the target single crystal silicon rod and the preset position is used to prepare the first battery product, and the rod segment between the preset position and the tail of the target single crystal silicon rod is used to prepare the second battery product, so that the resistivity of the target single crystal silicon rod can meet the requirements of the two battery products, and because the first distance from the preset position to the head of the single crystal silicon rod and the second distance from the preset position to the tail of the single crystal silicon rod both meet the processing length of the wire cutting machine, the split position of the single crystal silicon rod that meets the first battery product and the second battery product is located at the preset position, and the two single crystal silicon rods after cutting both meet the processing length of the cutting machine, so that the waste of the single crystal silicon rod can be reduced or even avoided, the utilization rate of the single crystal silicon rod is improved, and the processing efficiency of the wire cutting machine is improved.

[0046] For the above step S102, the target resistivity of the preset position is generally directly used to adjust the doping amount of the dopant in the silicon solution. Specifically, the specific implementation of adjusting the doping amount of the dopant in the silicon solution is as follows: the target resistivity of the preset position is used to calculate the doping concentration of the head of the target single crystal silicon rod; and the doping amount of the dopant in the silicon solution is calculated according to the calculated doping concentration of the head of the target single crystal silicon rod, so that the head of the target single crystal silicon rod drawn from the adjusted silicon solution meets the first battery product.

[0047] Compared with the prior art of directly detecting the resistivity of the head of the single crystal silicon rod, the disclosure provides that the target resistivity of the preset position is used to calculate the doping concentration of the head of the target single crystal silicon rod, which can reduce or even avoid the influence of oxygen on the detection result, so that the calculated doping concentration of the head of the target single crystal silicon rod can be more accurate. Further, because the resistivity of the head of the single crystal silicon rod and the doping concentration have a relatively strong correlation with the initial doping amount of the dopant in the silicon solution, the technical solution can more accurately adjust the doping amount of the dopant in the silicon solution according to the doping concentration of the head of the target single crystal silicon rod.

[0048] The specific implementation of calculating the doping concentration of the head of the target single crystal silicon rod is as follows:

[0049] The target doping concentration of the preset position is calculated by using the conversion relationship between the resistivity and the doping concentration and the target resistivity. Different conversion relationships are selected for different doping elements. The conversion relationship is described in detail below by taking phosphorus and boron as the doping elements.

[0050] For example, for the doping element being phosphorus element, the corresponding conversion relationship is shown in the following calculation formula group (A).

[0051] wherein, N D represents the target doping concentration of the doping element being phosphorus element; p represents the target resistivity; A0=-3.1083; A1=-3.2626; A2=-1.2196; A3=-0.13923; B1=1.0265; B2=0.38755; B3=0.041833.

[0052] For example, for the doping element being boron element, the corresponding conversion relationship is shown in the following calculation formula group (1).

[0053] wherein, N D represents the target doping concentration of the doping element being boron element; p represents the target resistivity.

[0054] After the target doping concentration is calculated, the specific implementation of calculating the doping concentration of the head of the target single crystal silicon rod can be as follows by using the target doping concentration, the solidification rate of the silicon solution corresponding to the preset position, and the segregation coefficient of the dopant.

[0055] The doping concentration of the head of the single crystal silicon rod is calculated by using the following calculation formula (2).

[0056] wherein, N t represents the calculated doping concentration of the head of the target single crystal silicon rod; N s represents the target doping concentration of the preset position of the target single crystal silicon rod; ω s represents the solidification rate of the silicon solution corresponding to the preset position; A represents the segregation coefficient of the dopant; wherein, the solidification rate of the silicon solution corresponding to the preset position generally refers to the proportion of the silicon solution that has been crystallized after the single crystal silicon rod is drawn to the preset position to the total solution before drawing. In addition, the segregation coefficient of the dopant is determined by the dopant itself, and is a constant value in the case of the dopant being determined.

[0057] Further, the specific implementation of calculating the doping amount of the dopant in the silicon solution is as follows: the initial doping concentration of the silicon solution for drawing the target single crystal silicon rod is calculated by using the following calculation formula (3).

[0058] wherein, N y represents the initial doping concentration of the silicon solution for drawing the target single crystal silicon rod; N trepresents the doping concentration of the head of the target single crystal silicon rod; A represents the segregation coefficient of the dopant; wherein the initial doping concentration of the silicon solution for drawing the target single crystal silicon rod refers to the doping concentration that the silicon solution needs to reach before drawing the target single crystal silicon rod.

[0059] On the basis of calculating the initial doping concentration of the silicon solution for drawing the target single crystal silicon rod, the doping amount of the dopant in the silicon solution is calculated by using the calculated initial doping concentration of the silicon solution and the volume of the silicon solution. Specifically, the product between the initial doping concentration and the volume of the silicon solution can be directly used to obtain the doping amount of the dopant, that is, the doping amount of the dopant is directly related to the volume of the silicon solution.

[0060] In addition, other indicators of the target single crystal silicon rod, such as oxygen content, minority carrier lifetime, carbon content, etc., can be controlled on the basis of the resistivity, by controlling the environmental conditions such as pressure, temperature, pulling rate, original purity, auxiliary material purity, etc., so that these other indicators can also meet the requirements of the first battery product and the second battery product while the resistivity meets the requirements of the first battery product and the second battery product.

[0061] Further, after the above step S103, the cut single crystal silicon rod segment can also be divided into two battery product lines for processing such as square bar processing, grinding and polishing, etc. In this process, since the single crystal silicon rod segment can meet the requirements of the corresponding battery product, the single crystal silicon rod segment can be maximally used without needing to be cut off to remove the part that does not meet the requirements of the battery product, thereby ensuring the utilization rate of the single crystal silicon rod.

[0062] Further, the disclosure embodiment also provides a resistivity control method of a single crystal silicon rod. As shown in FIG. 3, the resistivity control method of the single crystal silicon rod can include the following steps:

[0063] Step S301: selecting a preset position of a target single crystal silicon rod, wherein a first distance from the preset position to the head of the single crystal silicon rod is n times of the processing length of the wire cutting machine, and a second distance from the preset position to the tail of the single crystal silicon rod is m times of the processing length of the wire cutting machine, wherein n and m are positive integers;

[0064] The target single crystal silicon rod generally refers to the silicon rod segment from the starting position to the ending position of the isodiametric growth of the single crystal silicon rod, which is generally used to cut into two segments to meet the requirements of two battery products.

[0065] The preset position of the target single crystal silicon rod refers to a position of a cutting line used to cut the single crystal silicon rod into two segments. In the axial direction of the target single crystal silicon rod, a first distance from the preset position of the target single crystal silicon rod to the head of the single crystal silicon rod is n times the processing length of the wire cutting machine, and the first distance is generally a fixed value; in the axial direction of the target single crystal silicon rod, a second distance from the preset position of the target single crystal silicon rod to the tail of the single crystal silicon rod is m times the processing length of the wire cutting machine, and the second distance is also generally a fixed value, where n and m are positive integers. That is, the circumferential position of the preset position is relatively fixed relative to the head of the single crystal silicon rod and / or the tail of the single crystal silicon rod. The first distance and the second distance can meet the size requirements of the battery product, further improve the utilization rate of the single crystal silicon rod during processing of the single crystal silicon rod, and reduce waste of the single crystal silicon rod.

[0066] In addition, for the above-mentioned preset position, in addition to meeting the above-mentioned first distance and second distance meeting the processing length of the wire cutting machine (i.e., the first distance from the preset position to the head of the single crystal silicon rod is n times the processing length of the wire cutting machine, and the second distance from the preset position to the tail of the single crystal silicon rod is m times the processing length of the wire cutting machine, where n and m are positive integers), preferably, the preset position selected in step S101 can be further selected based on at least one of the following two conditions:

[0067] Condition 1: the oxygen content of the target single crystal silicon rod at the preset position is less than or equal to 5.5*10 17 atoms / cm 3 ;

[0068] Condition 2: the pulling speed at the preset position is greater than or equal to 1.5 mm / min when the target single crystal silicon rod is pulled.

[0069] More preferably, the first distance from the preset position to the head of the single crystal silicon rod is n times the processing length of the wire cutting machine, and the second distance from the preset position to the tail of the single crystal silicon rod is m times the processing length of the wire cutting machine, and at the same time, the preset position also meets the above two conditions.

[0070] Step S302: determining the target resistivity at the preset position, calculating the doping amount of the dopant in the silicon solution based on the target resistivity at the preset position, adding the dopant to the silicon solution based on the calculated doping amount of the dopant, and then pulling the target single crystal silicon rod by using the Czochralski method.

[0071] The target resistivity at the preset position can generally be determined according to the requirements of two battery products. The target resistivity can be a pre-set range, which can allow a certain adjustment error in pulling the target single crystal silicon rod, reduce the adjustment difficulty, and ensure the yield of the pulled target single crystal silicon rod.

[0072] Specifically, the target resistivity of the preset position is generally directly used to control the doping amount of the dopant in the silicon solution in the step S302. Specifically, the implementation of controlling the doping amount of the dopant in the silicon solution includes: calculating the doping concentration of the head of the target single crystal silicon rod according to the target resistivity of the preset position; and calculating the doping amount of the dopant in the silicon solution according to the calculated doping concentration of the head of the target single crystal silicon rod, so that the head of the target single crystal silicon rod drawn by the adjusted silicon solution meets the first battery product. Compared with the existing direct detection of the resistivity of the head of the single crystal silicon rod, the calculation of the doping concentration of the head of the target single crystal silicon rod according to the target resistivity of the preset position can reduce or even avoid the influence of oxygen on the detection result, so that the calculated doping concentration of the head of the target single crystal silicon rod is more accurate. Further, since the resistivity and the doping concentration of the head of the single crystal silicon rod have a relatively strong correlation with the initial doping amount of the dopant in the silicon solution, the technical solution can more accurately control the doping amount of the dopant in the silicon solution according to the doping concentration of the head of the target single crystal silicon rod.

[0073] The implementation of calculating the doping concentration of the head of the target single crystal silicon rod includes:

[0074] The target doping concentration of the preset position is calculated according to the conversion relationship between the resistivity and the doping concentration and the target resistivity; and the doping concentration of the head of the target single crystal silicon rod is calculated according to the target doping concentration, the solidification rate of the silicon solution corresponding to the preset position, and the segregation coefficient of the dopant. The conversion relationship between the resistivity and the doping concentration and the calculation formula of the doping concentration of the head of the target single crystal silicon rod have been described in detail in the above embodiments, and will not be repeated here.

[0075] Further, the implementation of calculating the doping amount of the dopant in the silicon solution includes: calculating the initial doping concentration of the silicon solution for drawing the target single crystal silicon rod according to the above calculation formula (3). The calculation formula (3) has been described in detail in the above embodiments, and will not be repeated here.

[0076] Subsequently, the initial doping concentration of the silicon solution and the volume of the silicon solution are used to calculate the doping amount of the dopant in the silicon solution. The product of the initial doping concentration and the volume of the silicon solution can be directly used to obtain the doping amount of the dopant, that is, the doping amount of the dopant is directly related to the volume of the silicon solution.

[0077] Compared with the resistivity of the head of the existing single crystal silicon rod, the technical scheme provided by the embodiment of the present disclosure can reduce the influence of high oxygen content on the resistivity detection result by detecting the target resistivity of the preset position, effectively improve the accuracy of the detected resistivity, and then based on the detected target resistivity of the preset position, adjust and control the doping amount of the dopant in the silicon solution, which can improve the accuracy of the resistivity adjustment of the target single crystal silicon rod.

[0078] Further, the embodiment of the present disclosure also provides a single crystal silicon rod. The single crystal silicon rod is prepared based on the preparation method of the single crystal silicon rod provided in the above embodiment.

[0079] The single crystal silicon rod can meet the needs of two battery products, that is, the single crystal silicon rod can be cut from the preset position, and the two cut single crystal silicon rod segments meet the needs of different battery products, so that the single crystal silicon rod can be used optimally and the waste of the single crystal silicon rod is reduced.

[0080] The above steps are provided only to help understand the method, structure and core idea of the present disclosure. For those skilled in the art in the technical field, some improvements and modifications can be made to the present disclosure without departing from the principles of the present disclosure, and these improvements and modifications also belong to the protection scope of the claims of the present disclosure.

Claims

1. A method for preparing a single crystal silicon rod, comprising: Step 1, selecting a preset position of a target single crystal silicon rod, wherein a first distance from the preset position to a head of the single crystal silicon rod is n times of a processing length of a wire cutting machine, and a second distance from the preset position to a tail of the single crystal silicon rod is m times of the processing length of the wire cutting machine, wherein n and m are positive integers; Step 2, determining a target resistivity at the preset position, calculating a doping amount of a dopant in a silicon solution according to the target resistivity at the preset position, adding the dopant into the silicon solution according to the calculated doping amount of the dopant, and then drawing the target single crystal silicon rod by using a Czochralski method; Step 3, cutting the target single crystal silicon rod at the preset position, wherein a rod segment between the head of the target single crystal silicon rod and the preset position is used to prepare a first battery product, and a rod segment between the preset position and the tail of the target single crystal silicon rod is used to prepare a second battery product.

2. The method of producing a single crystal silicon ingot according to claim 1, wherein The calculating of the doping amount of the dopant in the silicon solution according to the target resistivity at the preset position comprises: calculating a doping concentration of the head of the target single crystal silicon rod according to the target resistivity at the preset position; calculating the doping amount of the dopant in the silicon solution according to the calculated doping concentration of the head of the target single crystal silicon rod.

3. The method of producing a single crystal silicon ingot according to claim 2, wherein The calculating of the doping concentration of the head of the target single crystal silicon rod according to the target resistivity at the preset position comprises: calculating a target doping concentration at the preset position by using a conversion relationship between resistivity and doping concentration and the target resistivity; calculating the doping concentration of the head of the target single crystal silicon rod by using the target doping concentration, a solidification rate of the silicon solution corresponding to the preset position, and a segregation coefficient of the dopant.

4. The method of producing a single crystal silicon ingot according to any one of claims 1 to 3, wherein The oxygen content of the target single crystal silicon rod at the preset position is less than or equal to 5.5 x 10 17 atoms / cm 3 .

5. The method of producing a single crystal silicon ingot according to any one of claims 1 to 3, wherein A pulling speed at the preset position is greater than or equal to 1.5 mm / min when the target single crystal silicon rod is drawn.

6. The method of producing a single crystal silicon ingot according to any one of claims 1 to 3, wherein The target resistivity at the preset position satisfies that a resistivity of a rod segment from the preset position to the head of the single crystal silicon rod satisfies the first battery product, and a resistivity of a rod segment from the preset position to the tail of the single crystal silicon rod satisfies the second battery product. 7.The method according to claim 6, wherein, a first resistivity control range of a silicon wafer required by the first battery product and a second resistivity control range of a silicon wafer required by the second battery product have an overlapping interval, the target resistivity at the preset position of the target single crystal silicon rod is within the overlapping interval.

8. The method of producing a single crystal silicon ingot according to claim 1, wherein The head of the target single crystal silicon rod and the tail of the single crystal silicon rod are start and end positions of an equal diameter stage.

9. A single crystal silicon ingot, wherein, The single crystal silicon rod is prepared based on the method for preparing a single crystal silicon rod according to any one of claims 1 to 8.

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