Simulation method of dopant evaporation, crystal bar, battery piece and computer program product

Abstract

The invention relates to a dopant evaporation simulation method, a crystal bar, a battery piece and a computer program product, and the method comprises the steps: obtaining the axial resistivity which comprises the axial resistivity of the crystal bar after a predetermined amount of dopant is added and an equal-diameter stage is carried out under the conditions of a predetermined furnace pressure and a predetermined argon flow. The difference value between the axial resistivity and the expected axial resistivity is obtained, and the evaporation capacity of the dopant is calculated according to the difference value. And obtaining an evaporation constant according to the evaporation capacity of the dopant. Parameters of the crystal bar equal-diameter stage are obtained. And relevant parameters related to the evaporation constant in the parameters of the crystal bar equal-diameter stage are screened. And obtaining a relational expression between the relevant parameters and the evaporation constants. By adopting the method provided by the embodiment of the invention, the evaporation constant of the crystal bar in the equal-diameter stage can be obtained, so that the evaporation capacity of the dopant in the equal-diameter process is obtained, and the electrical characteristics of the crystal bar are favorably adjusted and the quality of the crystal bar is improved by calculating the evaporation capacity of the dopant in the equal-diameter process.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to a simulation method for dopant evaporation, a crystal rod, a battery cell and a computer program product. Background Art

[0002] With the development of technology, photovoltaic modules have become an important energy device in people's daily life. Manufacturing silicon rods is an important step in the production of photovoltaic modules. Usually, when manufacturing silicon rods, dopants need to be added to the silicon material to adjust the electrical properties of the silicon rods. However, at the stage of equal diameter of the crystal rod, the dopant will evaporate, resulting in a change in the ratio of dopant to silicon material in the crystal rod, affecting the electrical properties of the crystal rod. Summary of the invention

[0003] In view of this, the present application provides a simulation method for dopant evaporation, a crystal rod, a battery cell and a computer program product to facilitate the calculation of the evaporation amount of the dopant in the equal diameter stage.

[0004] In a first aspect, an embodiment of the present application provides a simulation method for dopant evaporation, the simulation method for dopant evaporation comprising:

[0005] Obtaining axial resistivity, wherein the axial resistivity includes the axial resistivity of a crystal rod after a predetermined amount of dopant is added and the crystal rod passes through a constant diameter stage under conditions of a predetermined furnace pressure and a predetermined argon gas flow rate;

[0006] Obtaining a difference between the axial resistivity and the expected axial resistivity, and calculating the dopant evaporation amount according to the difference;

[0007] Obtaining an evaporation constant according to the evaporation amount of the dopant;

[0008] Obtaining parameters of the crystal rod equal diameter stage;

[0009] Screening the parameters related to the evaporation constant among the parameters of the crystal rod equal diameter stage;

[0010] Obtain the relationship between relevant parameters and evaporation constant.

[0011] In a possible implementation manner, the predetermined furnace pressure ranges from 3 Torr to 15 Torr, and the predetermined argon gas flow rate ranges from 35 L / min to 170 L / min;

[0012] The mass of the dopant is m, the mass of the silicon material of the crystal rod is n, and 0.000015≤m / n≤0.000025.

[0013] In a possible implementation manner, the step of obtaining a difference between the axial resistivity and the expected axial resistivity and calculating the dopant evaporation amount according to the difference includes:

[0014] Measuring the resistivity of the crystal rod at intervals of 30 mm to 70 mm along the axial direction of the crystal rod to obtain the axial resistivity at the corresponding position;

[0015] According to the relationship between the expected axial resistivity and the expected length, the expected axial resistivity at the corresponding position along the axial direction of the crystal rod is obtained, the axial resistivity at the same position is compared with the expected axial resistivity to obtain a difference, and the dopant evaporation amount is calculated according to the difference.

[0016] In a possible implementation manner, the step of obtaining the parameters of the crystal rod equal diameter stage includes:

[0017] Obtain at least one of the following parameters: crystal length, weight of remaining material in the furnace, growth rate setting, crystal growth rate, main heater power, diameter value, actual argon flow rate, main chamber pressure value, actual crystal pulling speed, crystal weight, sub-chamber pressure value, crucible speed output, crystal speed output, average furnace pressure, average liquid surface temperature, actual crucible speed, actual crystal speed, water flow rate of water cooling jacket, liquid surface temperature measurement, and equal diameter time.

[0018] In a possible implementation manner, the step of screening the parameters related to the evaporation constant in the parameters of the crystal rod equal diameter stage includes:

[0019] Calculating the correlation coefficient p between various parameters of the crystal rod equal diameter stage and the evaporation constant;

[0020] When the correlation coefficient of the parameter satisfies p≤0.05, the corresponding parameter is the correlation parameter;

[0021] When the correlation coefficient of the parameter satisfies p>0.05, the corresponding parameter is not the correlation parameter.

[0022] In a possible implementation manner, the step of screening the parameters related to the evaporation constant in the parameters of the crystal rod equal diameter stage includes:

[0023] At least two related parameters related to the evaporation constant are screened and obtained.

[0024] In a possible implementation manner, the relevant parameters include crystal length, weight of remaining material in the furnace, actual argon flow rate, main chamber pressure value, average liquid surface temperature, and equal diameter time. The step of obtaining a relationship between the relevant parameters and the evaporation constant includes:

[0025] Obtaining a relationship between the crystal length, the weight of the remaining material in the furnace, the actual argon flow rate, the main chamber pressure value, the average liquid surface temperature, the equal diameter time and the evaporation constant;

[0026] The relationship between the crystal length, the weight of the remaining materials in the furnace, the actual argon flow rate, the main chamber pressure value, the average liquid surface temperature, the equal diameter time and the evaporation constant is processed by regression analysis to obtain the relationship between the final related variables and the evaporation constant;

[0027] The final related variable is the weight of the remaining material in the furnace. The relationship between the weight of the remaining material in the furnace and the actual evaporation constant is: E V =a+bW+cW 2 +dW 3 , where E -5 ≤a≤E -3 , -E -12 ≤b≤-E -10 , E -16 ≤a≤E -14 , -E -22 ≤d≤-E -20 , where E V is the evaporation constant, and W is the weight of the remaining material in the furnace.

[0028] A second aspect of the present application provides an electronic device, including:

[0029] A processor and a memory, wherein the memory is used to store at least one instruction, and when the instruction is loaded and executed by the processor, the electronic device executes the simulation method of dopant evaporation as described in any one of the above.

[0030] A third aspect of the present application provides a crystal rod, wherein the manufacturing parameters of the crystal rod are adjusted according to the evaporation constant of the dopant during the processing of the crystal rod, and the evaporation constant of the dopant when the crystal rod is in the shoulder release stage and the equal diameter stage is calculated by the simulation method of dopant evaporation described in any one of the above items.

[0031] A fourth aspect of the present application provides a battery cell, the battery cell comprising a silicon wafer, and the silicon wafer is processed from the crystal rod described above.

[0032] The present application relates to a simulation method for dopant evaporation, a crystal rod, a battery cell and a computer program product. The simulation method for dopant evaporation includes: obtaining axial resistivity, wherein the axial resistivity includes the axial resistivity of the crystal rod after a predetermined amount of dopant is added and the crystal rod passes through the equal diameter stage under the conditions of a predetermined furnace pressure and a predetermined argon gas flow rate. Obtain the difference between the axial resistivity and the expected axial resistivity, and calculate the dopant evaporation amount based on the difference. Obtain an evaporation constant based on the dopant evaporation amount. Obtain the parameters of the crystal rod equal diameter stage. Screen the relevant parameters related to the evaporation constant in the parameters of the crystal rod equal diameter stage. Obtain the relationship between the relevant parameters and the evaporation constant. By adopting the method provided in the embodiment of the present application, the evaporation constant of the crystal rod in the equal diameter stage can be obtained, thereby obtaining the evaporation amount of the dopant in the equal diameter process. By calculating the evaporation amount of the dopant in the equal diameter process, it is beneficial to adjust the electrical properties of the crystal rod and improve the quality of the crystal rod.

[0033] 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

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0035] Figure 1 A flow chart of a simulation method for dopant evaporation provided in an embodiment of the present application;

[0036] Figure 2 A relationship diagram between the simulated impurity number, the measured impurity number and the antimony evaporation amount provided in the examples of the present application;

[0037] Figure 3 A schematic diagram of the relationship between the axial resistivity and the length of the crystal rod obtained by measurement provided in an embodiment of the present application;

[0038] Figure 4 A schematic diagram showing the relationship between the simulated resistivity and the measured resistivity provided in the embodiment of the present application;

[0039] Figure 5 A relationship diagram between the axial resistivity and the crystal length after fitting provided in the embodiment of the present application;

[0040] Figure 6 A relationship diagram between the evaporation constant and the length of the crystal rod provided in the embodiment of the present application;

[0041] Figure 7 A flowchart of screening related variables provided in an embodiment of the present application;

[0042] Figure 8 A schematic diagram of the relationship between the relevant parameters and the evaporation constant provided in the embodiment of the present application;

[0043] Fig. 9 This is a relationship diagram between the weight of the remaining material in the furnace and the evaporation constant provided in the embodiment of the present application. DETAILED DESCRIPTION

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] In the process of photovoltaic module processing, it is usually necessary to manufacture crystal rods, and then process the crystal rods to obtain solar cells. In the process of processing the crystal rods, it is necessary to add specific impurity atoms to change the electrical properties of the material, thereby improving the photoelectric conversion efficiency of the solar cell. Usually, the commonly used dopants in photovoltaic cells mainly include n-type dopants and p-type dopants. N-type dopants usually include phosphorus (P) and antimony (Sb). By adding n-type dopants, additional free electrons can be introduced into the silicon lattice, thereby increasing the electron concentration of the material. P-type dopants usually include boron (B) and gallium (Ga). By adding p-type dopants, holes, that is, positions where electrons are missing, can be introduced into the silicon lattice, thereby increasing the hole concentration of the material.

[0049] Take antimony doping as an example. Antimony is a pentavalent element. During the doping process, it replaces atoms in the crystal lattice of semiconductor materials (such as silicon Si or germanium Ge), thereby introducing additional free electrons. In semiconductor materials such as silicon or germanium, each atom usually has four valence electrons, and they share electrons with adjacent atoms to form covalent bonds. When pentavalent antimony atoms are doped, since the silicon or germanium atom has one more valence electron, this extra electron will not participate in the formation of covalent bonds, so it can move freely in the lattice. These free electrons form conductive carriers in the doped semiconductor, which increases the conductivity of the material. Since these free electrons carry negative charges, the doped semiconductor is also called an N-type semiconductor (N stands for negative charge carriers, i.e., electrons). The conductivity of antimony-doped N-type semiconductors is enhanced. Compared with pure semiconductor materials, the conductivity of N-type semiconductors is better due to the increased concentration of self-retained electrons. The doping concentration will affect the guiding properties of N-type semiconductors. Generally, the higher the doping concentration, the higher the concentration of free electrons, and the better the conductivity of N-type semiconductors.

[0050] Take the dopant as antimony as an example, in the process of calculating the manufacturing of the crystal rod. When calculating the evaporation amount of the dopant in the equal diameter stage, multiple factors need to be involved. Usually, the evaporation characteristics of antimony, such as saturated vapor pressure, evaporation rate, etc., need to be considered, which needs to be determined through time data or theoretical calculations, and the process is relatively complicated. At the same time, the conditions of the doping process need to be considered. The temperature, pressure, doping time and other conditions in the doping process will affect the evaporation amount of antimony. These conditions need to be set according to the specific doping process, and the optimization of process conditions often needs to be determined through experiments. In the actual production process, these factors are all changing, so it is difficult to determine. At the same time, the uniformity of doping is also an important indicator in the doping process. The uniformity of doping depends not only on the control of the evaporation amount, but also on the temperature distribution and airflow distribution in the doping process. Due to the complexity of the doping process, theoretical calculations often need to be verified by experiments. Experimental verification not only takes time, but also requires corresponding experimental equipment and materials. In order to calculate the evaporation amount, it may be necessary to establish a complex physical model, including thermodynamic models, kinetic models, etc. The establishment and solution of these models require professional knowledge and skills, and it is difficult to establish models. Therefore, it is difficult to calculate the evaporation amount. When calculating the expected resistivity of the crystal rod, the evaporation amount is usually not calculated. In the equal diameter stage of the crystal rod, the dopant will evaporate, causing the ratio of the dopant to the silicon material to change, which in turn causes a difference between the resistivity of the crystal rod and the expected resistivity, affecting the performance of the photovoltaic cell.

[0051] like Figure 1As shown, the embodiment of the present application provides a simulation method for dopant evaporation, which can be used to obtain the evaporation constant of the dopant of the crystal rod after the equal diameter stage, and then the evaporation amount of the dopant of the crystal rod in the equal diameter stage can be obtained according to the evaporation constant. The simulation method for dopant evaporation includes:

[0052] The axial resistivity is obtained, wherein the axial resistivity includes the axial resistivity of the crystal rod after a predetermined amount of dopant is added and the crystal rod passes through a constant diameter stage under the conditions of a predetermined furnace pressure and a predetermined argon gas flow rate.

[0053] The difference between the axial resistivity and the expected axial resistivity is obtained, and the dopant evaporation amount is calculated based on the difference.

[0054] The evaporation constant is obtained according to the evaporation amount of the dopant.

[0055] Get the parameters of the crystal rod equal diameter stage.

[0056] Screen the parameters related to the evaporation constant in the parameters of the crystal rod equal diameter stage.

[0057] Obtain the relationship between relevant parameters and evaporation constant.

[0058] The crystal rod obtained after the equal-diameter stage can usually be the crystal rod after the equal-diameter stage, or it can be the crystal rod after the finishing stage, that is, the crystal pulling is completed. The crystal rod after the equal-diameter stage has been basically formed, so the axial resistivity of the crystal rod can be measured. In the equal-diameter stage of the crystal rod, the argon flow rate and furnace pressure are important factors affecting the quality of the crystal rod, so the argon flow rate and furnace pressure need to be controlled. The expected axial resistivity of the crystal rod is the axial resistivity of the crystal rod calculated based on data such as the feed ratio of the dopant and the silicon material. When calculating the expected resistivity, the evaporation amount of the dopant is not taken into account. After collecting and measuring the axial resistivity of the crystal rod, the measured axial resistivity is compared with the expected axial resistivity, and the difference in resistivity is obtained. The evaporation amount of the dopant in the equal-diameter stage can be calculated based on the difference in axial resistivity. The evaporation constant can be calculated based on the evaporation amount. The relationship between the evaporation amount of the dopant in the equal-diameter stage and the evaporation constant is N=E V AC1, where N is the dopant evaporation amount, A is the melt evaporation surface area, C1 is the dopant concentration in the melt, and E Vis the dopant evaporation constant, and the evaporation constant can be calculated according to the relationship. Collect the parameters of the crystal rod in the equal diameter stage. The purpose of collecting the parameters is to find out the parameters related to the evaporation constant. Therefore, when collecting the parameters of the crystal rod pulling in the equal diameter stage, collect as many as possible. After collecting the parameters, it is necessary to screen the parameters, delete the parameters that are not related to the evaporation constant, and obtain the parameters related to the evaporation constant. The parameters related to the evaporation constant are the relevant parameters, so as to reduce the variables in the relationship between the relevant parameters and the evaporation constant, and reduce the difficulty of obtaining the relationship. After obtaining the relevant parameters, obtain the relationship between the relevant parameters and the evaporation constant.

[0059] The method of calculating the evaporation amount of the dopant is to use the expected impurity number n1 obtained by simulation and the actual impurity number n2 to calculate, and n1-n2 can get the evaporation amount of the dopant. The impurity number can be calculated by impurity concentration * residual material volume, and the impurity concentration can be calculated by the formula Calculate, where N D is the dopant concentration in cubic centimeters (cm -3 ), ρ is the resistivity, the unit is ohm-centimeter (Ω·cm),

[0060] x=l gρ, A0=-3.1083, A1=-3.2626, A2=-1.2196, A3=-0.13923, B1=1.0265, B2=0.38755,

[0061] B3 = 0.041833. When calculating the evaporation amount, the dopant concentration can be calculated based on the resistivity. After the impurity number is calculated based on the dopant concentration, the expected impurity number and the actual impurity number can be obtained by respectively substituting the expected resistivity and the actual resistivity. The evaporation amount of the dopant can be obtained by the difference between the two. In a possible implementation, the dopant is antimony. The relationship between the expected impurity number (simulated impurity number), the actual impurity number (measured impurity number) and the evaporation amount of antimony is as follows: Figure 2 shown.

[0062] After obtaining the relationship between the relevant parameters and the evaporation constant, in the subsequent crystal rod manufacturing process, the values ​​of the relevant parameters corresponding to the crystal rod can be obtained, and the evaporation constant of the crystal rod can be obtained according to the relationship between the relevant parameters and the evaporation constant. Then, the evaporation amount of the crystal rod in the equal diameter stage can be calculated according to the relationship between the evaporation constant and the evaporation amount, so that when calculating the expected axial resistivity of the crystal rod, the evaporation amount can be introduced for calculation, which is conducive to improving the accuracy of the expected axial resistivity of the crystal rod, and can better predict the electrical characteristics of the crystal rod, so as to improve the quality of the crystal rod. In the process of batch production of crystal rods, it is conducive to keeping the doping concentration of each crystal rod consistent, improving the consistency and reliability of the doping concentration between different crystal rods, and then improving the quality of photovoltaic cells processed by crystal rods. By calculating the evaporation constant and evaporation amount of the crystal rod in the equal diameter stage, it is conducive to optimizing the doping process, adjusting the parameters of the crystal rod in the processing process according to the evaporation amount of the dopant in the equal diameter stage, which is conducive to avoiding excessive use of dopants and reducing waste of dopants, thereby helping to reduce costs.

[0063] Through the scheme provided in the embodiment of the present application, the evaporation behavior of different equal diameter conditions can be simulated and predicted through the relationship between the relevant parameters and the evaporation constant, and the expected doping effect can be obtained, which is conducive to reducing the number of experiments and costs during crystal rod processing. By obtaining the relationship between the relevant parameters and the evaporation constant in the equal diameter stage, the difficulty of calculating the evaporation amount of the dopant in the equal diameter stage of the crystal rod can be reduced, which is more in line with actual production needs.

[0064] In a possible implementation, the predetermined furnace pressure ranges from 3Tprr to 15Torr, and the argon flow rate ranges from 35L / min to 170L / min. When manufacturing the crystal rod, the mass of the dopant used is m, the mass of the silicon material is n, and 0.000015≤m / n≤0.000025.

[0065] The mass of the dopant can be the mass of antimony element, and the mass of the silicon material can be the mass of the polysilicon that can be put in. By limiting the ratio of the dopant to the silicon material, the expected axial resistivity of the crystal rod can be obtained, so as to compare it with the axial resistivity obtained by actual processing, and then the evaporation amount of the dopant can be obtained through corresponding calculation according to the difference between the actual axial resistivity and the expected axial resistivity.

[0066] The feeding amount of polysilicon can range from 800kg to 1000kg, and the feeding amount of polysilicon is 800kg, 820kg, 840kg, 860kg, 880kg, 900kg, 920kg, 940kg, 960kg, 980kg, 1000kg, etc. The mass of antimony can range from 15g to 20g, and the mass of antimony can be 15g, 16g, 17g, 18g, 19g, 20g, etc. In a possible implementation, in the process of obtaining the relationship between the relevant parameters and the evaporation constant, the feeding amount of polysilicon of the manufactured crystal rod can be 920kg, and the mass of antimony can be 17g. The specific ratio of polysilicon and antimony can be adjusted according to the electrical characteristics of the crystal rod actually produced.

[0067] The furnace pressure can be 3 Torr, 4 Torr, 5 Torr, 6 Torr, 7 Torr, 8 Torr, 9 Torr, 10 Torr, 11 Torr, 12 Torr, 13 Torr, 14 Torr, 15 Torr, etc. The argon flow rate can be 35 L / min, 45 L / min, 55 L / min, 65 L / min, 75 L / min, 85 L / min, 95 L / min, 105 L / min, 115 L / min, 125 L / min, 135 L / min, 145 L / min, 155 L / min, 165 L / min, 170 L / min, etc. By limiting the argon flow rate and furnace pressure, the manufacturing conditions of the crystal rod equal diameter stage can be restricted. After obtaining the relationship between the relevant parameters and the evaporation parameters, when the crystal rod is equalized in diameter under the same argon flow rate and furnace pressure conditions, the corresponding evaporation constant can be obtained according to the relationship between the relevant parameters and the evaporation constant, and then the evaporation amount of the dopant can be obtained, which is conducive to calculating the expected axial resistivity of the crystal rod and improving the accuracy of the calculation results.

[0068] In a possible implementation manner, the step of obtaining a difference between the axial resistivity and the expected axial resistivity and calculating the dopant evaporation amount according to the difference includes:

[0069] The resistivity of the crystal rod is measured at intervals of 30 mm to 70 mm along the axial direction of the crystal rod to obtain the axial resistivity at the corresponding position.

[0070] According to the relationship between the expected axial resistivity and the expected length, the expected axial resistivity at the corresponding position along the axial direction of the crystal rod is obtained, the axial resistivity at the same position is compared with the expected axial resistivity to obtain a difference, and the dopant evaporation amount is calculated according to the difference.

[0071] When obtaining the axial resistivity, the detection distance can be 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, etc. The specific selection can be based on the actual measurement requirements. By measuring the resistivity at different positions of the crystal rod, multiple data can be obtained. In subsequent calculations, the difference between multiple axial resistivities and expected axial resistivities can be obtained, and then multiple data can be obtained, which can improve the richness of the data, thereby facilitating the improvement of the accuracy of subsequent calculations.

[0072] Before manufacturing the crystal rod, the expected resistivity of the crystal rod is usually predicted based on the proportion of dopant and silicon material, and the relationship between the expected axial resistivity and the expected length of the crystal rod is obtained. The relationship between the expected axial resistivity and the expected length and the relationship between the actually measured axial resistivity and the actual length can be modeled separately. By comparing the two models, the difference between the expected axial resistivity and the actual axial resistivity can be obtained. This method is conducive to obtaining the difference between multiple expected axial resistivities and measured axial resistivities. The evaporation amount of the crystal rod in the equal diameter stage is calculated through multiple sets of data, which is conducive to improving the accuracy of the evaporation amount calculation. Figure 3 As shown in the figure, the relationship between the axial resistivity and the length of the crystal rod based on the actual measurement provided by the embodiment of the present application is established, wherein the horizontal axis is the length of the crystal rod, in mm, and the vertical axis is the axial resistivity of the crystal rod, in Ω·cm. The relationship between the expected resistivity (simulated resistivity) and the actual resistivity (measured resistivity) is shown in the figure. Figure 4 As shown in the figure, since the evaporation amount is not introduced when calculating the expected resistivity, there will be a difference between the expected resistivity and the actual resistivity. By simulating and calculating the evaporation constant and evaporation amount of the dopant at different lengths, and adding the evaporation amount to the calculation of the expected resistivity, the evaporation constant is adjusted to make the expected resistivity curve close to the actual resistivity, and improve the fit between the expected axial resistivity and the expected crystal rod length curve and the measured axial resistivity and crystal rod length curve. Usually, the fit needs to be improved to no less than 99.8%. Figure 5 The relationship between the axial resistivity and the crystal length after fitting is shown in Figure 2. Since the fitting degree is not less than 99.8%, the two curves almost overlap. According to the calculation, we can get the following: Figure 6 The relationship between the evaporation constant and the length of the crystal rod is shown, wherein the horizontal axis is the length of the crystal rod, in cm, and the vertical axis is the evaporation constant, in cm / s.

[0073] In one possible embodiment, obtaining the parameters of the crystal rod in the equal-diameter stage includes obtaining the crystal length, the weight of the remaining material in the furnace, the growth rate setting, the crystal growth rate, the main heater power, the diameter value, the actual argon flow rate, the main chamber pressure value, the actual crystal pulling speed, the crystal weight, the auxiliary chamber pressure value, the crucible speed output, the crystal speed output, the average furnace pressure, the average liquid surface temperature, the actual crucible speed, the actual crystal speed, the water flow rate of the water-cooling jacket, the liquid surface temperature measurement, and at least one of the parameters of the equal-diameter time.

[0074] In the data collection stage, the richer the data collected, the more conducive it is to finding the parameters that can affect the evaporation constant, and thus to obtaining the relationship between the relevant parameters and the evaporation constant.

[0075] like Figure 7 As shown, in a possible implementation manner, the step of screening the parameters related to the evaporation constant in the parameters of the crystal rod equal diameter stage includes:

[0076] Calculate the correlation coefficient p between each parameter and the evaporation constant at the stage of equal diameter of the crystal rod;

[0077] When the correlation coefficient of a parameter satisfies p≤0.05, the corresponding parameter is a relevant parameter;

[0078] When the correlation coefficient of a parameter satisfies p>0.05, the corresponding parameter is not a relevant parameter.

[0079] By calculating the correlation coefficient between each parameter and the evaporation constant, the correlation between each parameter and the evaporation constant can be obtained. The higher the correlation with the evaporation constant, the greater the influence of the corresponding parameter on the evaporation constant, and the smaller the correlation with the evaporation constant, the smaller the influence of the corresponding parameter on the evaporation constant. Further, the greater the influence of the parameter on the evaporation constant, the greater the influence of the parameter on the evaporation amount of the dopant, and the smaller the influence of the parameter on the evaporation constant, the smaller the influence of the parameter on the evaporation amount of the dopant. When calculating the correlation coefficient, an appropriate threshold range can be set. When the correlation coefficient of the parameter is within the threshold range, the correlation between the parameter and the evaporation constant and the evaporation amount is large. When the correlation coefficient of the parameter is not within the threshold range, the correlation between the parameter and the evaporation constant and the evaporation amount is small, and its influence on the evaporation constant and the evaporation amount can be ignored. The threshold of the correlation coefficient can be set with 0.05 as the boundary. When the correlation coefficient of the parameter is ≤0.05, it is considered that the parameter is related to the evaporation constant. When the correlation coefficient of the parameter is >0.05, it is considered that the parameter is not related to the evaporation constant, and the parameter related to the evaporation constant is the relevant parameter.

[0080] As shown in Table 1 below, in a possible implementation, when calculating the relevant parameters, relevant analysis software, including but not limited to SPSS, Minitab, SPSSAU and other software, can be used to place the evaporation amount in the equal diameter stage in the dependent variable Y of the analysis item, and the remaining items in the analysis item X. In a possible implementation, after actual sampling and calculation, the following Table 1 is obtained. When the correlation between the parameter and the evaporation amount is high, the correlation between the parameter and the evaporation constant is also relatively high; when the correlation between the parameter and the evaporation amount is low, the correlation between the parameter and the evaporation constant is also relatively low, so the correlation between the parameter and the evaporation constant can be obtained through the correlation between the parameter and the evaporation amount.

[0081] Table 1

[0082]

[0083]

[0084] Table 1 shows the correlation between each parameter and the evaporation amount in the equal diameter process, and thus the correlation between each parameter and the evaporation constant. The parameters marked with "*" are those with a correlation parameter p less than 0.05, and the parameters marked with "**" are those with a correlation parameter p less than 0.01. It should be noted that the data in the table are not the values ​​of the correlation parameter p, but another form of expression of the correlation parameter. A positive value indicates that the corresponding parameter is positively correlated with the evaporation amount, and a negative value indicates that the corresponding parameter is negatively correlated with the evaporation amount. Parameters related to the evaporation amount can be considered to be related to the evaporation constant.

[0085] The collected parameters can be screened by calculating the relevant parameters of the coefficients, so as to obtain the relevant parameters related to the evaporation constant. When obtaining the relationship, the relationship between the relevant parameters and the evaporation constant can be obtained. This method is conducive to reducing the number of parameters in the relationship, so that the relationship can be simplified. When calculating the evaporation constant of the crystal rod in the equal diameter stage, it is sufficient to collect the data of the relevant parameters, and it is not necessary to collect all the parameters in the manufacturing process, which is conducive to reducing the difficulty of calculating the evaporation constant and improving the calculation efficiency. When modeling the relationship between the parameters and the evaporation constant, the number of parameters can be reduced by screening, which is conducive to reducing the difficulty of modeling.

[0086] In a possible implementation, the step of screening the parameters related to the evaporation constant in the parameters of the crystal rod equal diameter stage includes:

[0087] At least two relevant parameters related to the evaporation constant were screened.

[0088] When there is only one relevant parameter obtained through correlation coefficient screening, the relationship between the relevant parameter and the evaporation constant can be obtained.

[0089] In order to improve the accuracy of the calculation of the evaporation constant, at least two relevant parameters related to the evaporation constant are obtained by screening, which can reduce the difficulty of modeling and calculation and improve the accuracy of the calculation of the evaporation constant.

[0090] like Figure 8 As shown, in a possible implementation manner, the relevant parameters may include crystal length, weight of remaining materials in the furnace, actual argon flow rate, main chamber pressure value, average liquid surface temperature, and equal diameter time. The step of obtaining the relationship between the relevant parameters and the evaporation constant includes:

[0091] Obtain the relationship between crystal length, weight of remaining material in the furnace, actual argon flow rate, main chamber pressure value, average liquid surface temperature, equal diameter time and evaporation constant.

[0092] The relationship between crystal length, weight of remaining materials in the furnace, actual argon flow rate, main chamber pressure value, average liquid surface temperature, equal diameter time and evaporation constant was processed through regression analysis to obtain the relationship between the final related variables and the evaporation constant.

[0093] The final related variable is the weight of the remaining material in the furnace. The relationship between the weight of the remaining material in the furnace and the actual evaporation constant is: E V =a+bW+cW 2 +dW 3 , where E -5 ≤a≤E -3 , -E -12 ≤b≤-E -10 , E -16 ≤a≤E -14 , -E -22 ≤d≤-E -20 , where E V is the evaporation constant, and W is the weight of the remaining material in the furnace.

[0094] In a possible implementation, the relationship between the weight of the remaining material in the furnace and the actual evaporation constant can be: E V =0.000301638354296996+(-2.84707976156801E -11 W)+2.37401312033123E -15 W 2 +(-2.82524056437763E -21 W 3 ), where E V is the evaporation constant, and W is the weight of the remaining material in the furnace.

[0095] When screening the collected parameters, the crystal length, the weight of the remaining materials in the furnace, the actual argon flow rate, the main chamber pressure value, the average liquid surface temperature, and the equal diameter time are obtained. Through mathematical integration, the relationship between each related parameter and the evaporation constant can be integrated into a relationship. During manufacturing, the evaporation constant can be obtained through the corresponding data, and the evaporation amount of the dopant can be calculated based on the evaporation constant. The relationship between the evaporation constant and the related variables is as follows: Fig. 9 As shown, Fig. 9 It is the relationship between the weight of the remaining material in the furnace and the evaporation constant, where the horizontal axis is the weight of the remaining material in the furnace, the unit is g, and the vertical axis is the evaporation constant, the unit is cm / s.

[0096] After obtaining the relationship between the relevant variables and the evaporation constant, the obtained relationship can be optimized by regression analysis, and the obtained relationship is processed by model setting, data collection, data preprocessing, parameter estimation, model diagnosis, model verification, result analysis and other steps. After processing, some relevant parameters will become constant terms in the relationship, that is, they will not affect the evaporation constant. After actual calculation, the relevant parameters that become constant terms include actual argon flow, main chamber pressure, and average liquid surface temperature. Then, the variance expansion factor (variance expansion factor, VIF) is processed, and the crystal length and equal diameter time in the relevant variables can be deleted. The remaining relevant parameters are the final relevant variables, and the relationship between the final relevant variables and the evaporation constant is obtained. In the scheme provided in the embodiment of the present application, after regression analysis, the final relevant variable obtained is the weight of the remaining material in the furnace, and the relationship finally obtained is the relationship between the weight of the remaining material in the furnace and the evaporation constant. The relationship between the relevant parameters and the evaporation constant can be further optimized by regression analysis, and the number of relevant variables in the relationship can be reduced, thereby reducing the difficulty of calculation and modeling, improving the efficiency of obtaining the evaporation constant, and more in line with actual production needs.

[0097] After obtaining the relationship between the relevant variables and the evaporation constant, in the subsequent crystal rod manufacturing process, the evaporation constant of the crystal rod in the equal-diameter process can be obtained according to the relationship, and then the evaporation amount of the dopant can be obtained according to the evaporation constant. Before production, the expected axial resistivity of the crystal rod after the equal-diameter stage can be calculated, and the evaporation amount can be added in the calculation process, which is conducive to improving the accuracy of the calculation and better obtaining the electrical characteristics of the crystal rod after processing, so that the manufacturing process parameters of the crystal rod can be adjusted according to needs to improve the production quality of the crystal rod.

[0098] As shown in Table 2 below, the process parameters of the crystal rod equalizing stage before the manufacturing process parameters of the crystal rod provided in the embodiment of the present application are adjusted:

[0099] Table 2

[0100]

[0101] In Table 2 above, length refers to the change in length of the crystal rod in the crystal rod equal diameter stage, in mm, and growth setting refers to the rate of the crystal rod during the growth process, in mm / hr. Crucible rotation refers to the rotation rate of the crucible in the equal diameter stage, in rpm. Crystal rotation refers to the rotation rate of the crystal in the equal diameter stage, in rpm. Argon flow rate refers to the flow rate of argon in the crystal rod equal diameter stage, in L / min. Pressure setting refers to the furnace pressure in the crystal rod equal diameter stage, in Torr. Diameter refers to the diameter size of the crystal rod in the equal diameter stage, in mm. Power change refers to temperature compensation by adjusting the power in the crystal rod equal diameter stage. In the crystal rod equal diameter process, the melt temperature may be insufficient. Therefore, it is necessary to adjust the power for temperature compensation so that the equal diameter process can continue and reduce the risk of wire breakage. Temperature change refers to the change in melt temperature. Bottom power refers to the power of the bottom heater. Liquid mouth distance refers to the distance from the lower edge of the guide tube to the liquid surface in the crucible, in mm. The maximum value of liquid level control is compensated according to the value of liquid-to-mouth distance. In the process of crystal rod manufacturing, the liquid-to-mouth distances in the shoulder release stage and the equal-diameter stage are different. After entering the equal-diameter stage from the shoulder release stage, the liquid-to-mouth distance needs to be adjusted. During the adjustment process, the adjustment rate of the liquid-to-mouth distance is controlled by the maximum value of liquid level control.

[0102] Since the process parameters of the crystal rod in the equal diameter stage in Table 2 are process parameters without considering the evaporation amount of the dopant, the solution provided in the embodiment of the present application can obtain the evaporation constant of the crystal rod in the equal diameter stage. After obtaining the evaporation constant of the equal diameter stage, the evaporation amount of the dopant in the equal diameter stage can be calculated, so that the process parameters of the equal diameter stage can be adjusted according to the evaporation amount of the dopant in the equal diameter stage. The adjusted process parameters are shown in Table 3 below:

[0103] Table 3

[0104]

[0105] In the equal diameter stage, the crucible rotation, argon flow rate and pressure setting can be adjusted. The argon flow rate and pressure setting can change with the growth of the crystal rod. By adjusting the crucible rotation, argon flow rate and pressure setting, it is helpful to reduce the evaporation of dopants, thereby improving the electrical properties of the crystal rod. At the same time, by adjusting the above parameters, it is also helpful to reduce the oxygen content of the crystal rod and improve the quality of the crystal rod.

[0106] Based on the simulation method of dopant evaporation involved in the above embodiments, the embodiment of the present application also provides a crystal rod. During the processing of the crystal rod, the manufacturing parameters of the crystal rod in the equal diameter process can be adjusted according to the evaporation constant of the dopant, so as to adjust the electrical characteristics of the crystal rod. When calculating the evaporation constant of the dopant, the above simulation method of dopant evaporation can be used for calculation. The embodiment of the present application also provides a battery cell, which includes a silicon wafer, and the silicon wafer can be processed by the above silicon rod.

[0107] Based on the simulation method of dopant evaporation involved in the above embodiments, the embodiment of the present application also provides a computer program product, which includes executable instructions. When the executable instructions are executed on a computer, the computer executes the simulation method of dopant evaporation involved in any of the above embodiments.

[0108] The embodiment of the present application provides a simulation method for dopant evaporation, a crystal rod, a battery cell and a computer program product. The simulation method for dopant evaporation includes: obtaining axial resistivity, wherein the axial resistivity includes the axial resistivity of the crystal rod after a predetermined amount of dopant is added and the crystal rod passes through the equal diameter stage under the conditions of a predetermined furnace pressure and a predetermined argon gas flow rate. Obtain the difference between the axial resistivity and the expected axial resistivity, and calculate the dopant evaporation amount based on the difference. Obtain an evaporation constant based on the dopant evaporation amount. Obtain the parameters of the crystal rod equal diameter stage. Screen the relevant parameters related to the evaporation constant in the parameters of the crystal rod equal diameter stage. Obtain the relationship between the relevant parameters and the evaporation constant. By adopting the method provided in the embodiment of the present application, the evaporation constant of the crystal rod in the equal diameter stage can be obtained, thereby obtaining the evaporation amount of the dopant in the equal diameter process. By calculating the evaporation amount of the dopant in the equal diameter process, it is beneficial to adjust the electrical properties of the crystal rod and improve the quality of the crystal rod.

[0109] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for simulating dopant evaporation, characterized in that: The simulation method of dopant evaporation comprises: Obtaining axial resistivity, wherein the axial resistivity includes the axial resistivity of a crystal rod after a predetermined amount of dopant is added and the crystal rod passes through a constant diameter stage under conditions of a predetermined furnace pressure and a predetermined argon gas flow rate; Obtaining a difference between the axial resistivity and the expected axial resistivity, and calculating the dopant evaporation amount according to the difference; Obtaining an evaporation constant according to the evaporation amount of the dopant; Obtaining parameters of the crystal rod equal diameter stage; Screening the parameters related to the evaporation constant among the parameters of the crystal rod equal diameter stage; Obtain the relationship between relevant parameters and evaporation constant.

2. The method for simulating dopant evaporation according to claim 1, characterized in that: The predetermined furnace pressure ranges from 3 Torr to 15 Torr, and the predetermined argon gas flow rate ranges from 35 L / min to 170 L / min; The mass of the dopant is m, the mass of the silicon material of the crystal rod is n, and 0.000015≤m / n≤0.000025.

3. The method for simulating dopant evaporation according to claim 1, characterized in that: The step of obtaining the difference between the axial resistivity and the expected axial resistivity and calculating the dopant evaporation amount according to the difference comprises: Measuring the resistivity of the crystal rod at intervals of 30 mm to 70 mm along the axial direction of the crystal rod to obtain the axial resistivity at the corresponding position; According to the relationship between the expected axial resistivity and the expected length, the expected axial resistivity at the corresponding position along the axial direction of the crystal rod is obtained, the axial resistivity at the same position is compared with the expected axial resistivity to obtain a difference, and the dopant evaporation amount is calculated according to the difference.

4. The method for simulating dopant evaporation according to claim 1, characterized in that: The step of obtaining the parameters of the crystal rod equal diameter stage includes: Obtain at least one of the following parameters: crystal length, weight of remaining material in the furnace, growth rate setting, crystal growth rate, main heater power, diameter value, actual argon flow rate, main chamber pressure value, actual crystal pulling speed, crystal weight, sub-chamber pressure value, crucible speed output, crystal speed output, average furnace pressure, average liquid surface temperature, actual crucible speed, actual crystal speed, water flow rate of water cooling jacket, liquid surface temperature measurement, and equal diameter time.

5. The method for simulating dopant evaporation according to claim 1, characterized in that: The step of screening the parameters related to the evaporation constant in the parameters of the crystal rod equal diameter stage includes: Calculating the correlation coefficient p between various parameters of the crystal rod equal diameter stage and the evaporation constant; When the correlation coefficient of the parameter satisfies p≤0.05, the corresponding parameter is the correlation parameter; When the correlation coefficient of the parameter satisfies p>0.05, the corresponding parameter is not the correlation parameter.

6. The method for simulating dopant evaporation according to any one of claims 1 to 5, characterized in that: The step of screening the parameters related to the evaporation constant in the parameters of the crystal rod equal diameter stage includes: At least two related parameters related to the evaporation constant are screened and obtained.

7. The method for simulating dopant evaporation according to claim 6, characterized in that: The relevant parameters include crystal length, weight of remaining materials in the furnace, actual argon flow rate, main chamber pressure value, average liquid surface temperature, and equal diameter time. The step of obtaining the relationship between the relevant parameters and the evaporation constant includes: Obtaining a relationship between the crystal length, the weight of the remaining material in the furnace, the actual argon flow rate, the main chamber pressure value, the average liquid surface temperature, the equal diameter time and the evaporation constant; The relationship between the crystal length, the weight of the remaining materials in the furnace, the actual argon flow rate, the main chamber pressure value, the average liquid surface temperature, the equal diameter time and the evaporation constant is processed by regression analysis to obtain the relationship between the final related variables and the evaporation constant; The final related variable is the weight of the remaining material in the furnace. The relationship between the weight of the remaining material in the furnace and the actual evaporation constant is: E V =a+bW+cW 2 +dW 3 , where E -5 ≤a≤E -3 , -E -12 ≤b≤-E -10 , E -16 ≤a≤E -14 , -E -22 ≤d≤-E -20 , where E V is the evaporation constant, and W is the weight of the remaining material in the furnace.

8. A crystal rod, characterized in that: During the processing of the crystal rod, the manufacturing parameters of the crystal rod are adjusted according to the evaporation constant of the dopant, and the evaporation constant of the dopant when the crystal rod is in the shoulder release stage and the equal diameter stage is calculated by the simulation method of dopant evaporation according to any one of claims 1 to 7.

9. A battery cell, characterized in that: The battery cell comprises a silicon wafer, and the silicon wafer is processed from the crystal rod according to claim 8.

10. A computer program product, characterized in that The computer program product comprises executable instructions, and when the executable instructions are executed on a computer, the computer is caused to execute the simulation method of dopant evaporation according to any one of claims 1 to 7.

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