Manufacturing method of silicon single crystal rod and silicon wafer

Abstract

The invention relates to the technical field of monocrystalline silicon manufacturing, provides a manufacturing method of a monocrystalline silicon rod and a silicon wafer, and at least facilitates the control of the resistivity uniformity of the monocrystalline silicon rod. The method comprises the steps that a test single crystal silicon rod is prepared, an initial doping concentration model is simulated according to the test single crystal silicon rod, and the initial doping concentration model is characterized in that in the equal-diameter process, the change trend of the concentration of a doping agent in the test single crystal silicon rod along with time is tested; the initial doping concentration model is optimized according to the target concentration interval to obtain a prediction model, the prediction model represents the variation trend of the concentration of the doping agent in the single crystal silicon rod along with time under the condition of multiple times of doping agent supplementation in the equal-diameter process, the prediction model comprises multiple concentration inflection points and multiple doping supplementation time points, and the concentration inflection points are different from the doping supplementation time points; each supplementary doping time point is correspondingly prior to a concentration inflection point; and preparing a target single crystal silicon rod, and in the equal-diameter process of preparing the target single crystal silicon rod, supplementing the dopant according to the supplementing time point.

Description

Technical Field

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

[0002] During the growth of single crystal silicon, dopants such as boron (B), phosphorus (P), arsenic (As), antimony (Sb), etc. may be used to adjust the resistivity of the single crystal silicon rod. In the melting process, the dopant is put into a crucible together with the polycrystalline silicon raw material, and the dopant is melted together with the polycrystalline silicon by heating with a heater, thereby producing a single crystal silicon rod including the silicon ingot dopant.

[0003] However, due to the influence of the segregation coefficient and volatility of the dopant, the resistivity of different positions of the single crystal silicon rod is different. For example, the segregation coefficient of phosphorus in silicon is small and the evaporation rate is low, which causes the resistivity of the single crystal silicon rod to gradually decrease from the head to the tail, and the resistivity difference between the head and the tail of the single crystal silicon rod is large; due to the fast evaporation rate of antimony, the antimony concentration in the silicon melt decreases during the crystal pulling process, which in turn causes the resistivity of the tail of the single crystal silicon rod to increase. Summary of the invention

[0004] The embodiments of the present application provide a method for manufacturing a single crystal silicon rod and a silicon wafer, which are at least beneficial for controlling the resistivity uniformity of the single crystal silicon rod.

[0005] According to some embodiments of the present application, on the one hand, the embodiments of the present application provide a method for manufacturing a single crystal silicon rod, including: preparing a test single crystal silicon rod, adding a dopant in the melting process of preparing the test single crystal silicon rod; simulating an initial doping concentration model, the initial doping concentration model being characterized by the concentration trend of the dopant in the test single crystal silicon rod over time in the equal diameter process; setting a target concentration interval, the minimum value of the target concentration interval being a first concentration, and the maximum value of the target concentration interval being a second concentration; optimizing the initial doping concentration model according to the target concentration interval to obtain a prediction model, the prediction model being characterized by , in the equal-diameter process, when the dopant is added multiple times, the concentration of the dopant in the single crystal silicon rod changes with time, and the concentration of the dopant in the single crystal silicon rod is always between the first concentration and the second concentration. The prediction model includes multiple concentration inflection points and multiple supplementary doping time points. The supplementary doping time point is the time point when the dopant is added, and the concentration inflection point is the time point when the dopant concentration in the single crystal silicon rod begins to increase or decrease after the dopant is added. Each supplementary doping time point corresponds to a concentration inflection point. Prepare the target single crystal silicon rod, and in the equal-diameter process of preparing the target single crystal silicon rod, add the dopant according to the supplementary doping time point.

[0006] In some embodiments, at each supplementary doping time point, the mass of the supplementary dopant is the same; or the time difference between any two consecutive supplementary doping time points is the same.

[0007] In some embodiments, the initial doping concentration model is optimized according to the target concentration range to obtain a prediction model, including: calculating a preset supplementary doping dosage based on the first concentration and the second concentration; obtaining the first time point when the concentration of the dopant in the test single crystal silicon rod reaches the first concentration or the second concentration for the first time in the initial doping concentration model; optimizing the initial doping concentration model for the first time in combination with the evaporation coefficient and segregation coefficient of the dopant and the preset supplementary doping dosage, and during the first optimization process, repeatedly adjusting the first supplementary doping time point so that the concentration inflection point is within the target concentration range; re-optimizing the previously optimized initial doping concentration model in chronological order, adjusting the corresponding supplementary doping time points on the condition that the mass of the dopant added before the concentration of the dopant in the initial doping concentration model reaches the first concentration or the second concentration each time, so as to obtain a prediction model.

[0008] In some embodiments, the preset supplementary doping amount is greater than or equal to 1 / 3 of the difference between the second concentration and the first concentration, and less than or equal to 2 / 3 of the difference between the second concentration and the first concentration.

[0009] In some embodiments, optimizing the initial doping concentration model according to the target concentration range to obtain a prediction model includes: obtaining the first time point in the initial doping concentration model when the concentration of the dopant in the test single crystal silicon rod reaches the first concentration or the second concentration for the first time; calculating the first supplementary doping time point according to the first time point and the start time point of the equal diameter process, and the time difference between the first supplementary doping time point and the start time point of the equal diameter process is the supplementary doping time difference; optimizing the initial doping concentration model for the first time in combination with the first supplementary doping time point and the evaporation coefficient and segregation coefficient of the dopant, and in the process of the first optimization, repeatedly adjusting the mass of the first dopant so that the concentration inflection point is within the target concentration range; re-optimizing the initial doping concentration model optimized previously in chronological order, and adjusting the mass of the corresponding dopant on the condition that the time difference between the previous supplementary doping time point and the next supplementary doping time point is equal to the supplementary doping time difference, so as to obtain a prediction model.

[0010] In some embodiments, the time difference between the first supplementary doping time point and the start time point of the equal diameter process is the initial time difference, and the supplementary doping time difference is greater than 1 / 3 of the initial time difference and less than 2 / 3 of the initial time difference.

[0011] In some embodiments, as the time of the equal diameter process increases, the time difference between different supplementary doping time points and the corresponding concentration inflection points gradually decreases.

[0012] In some embodiments, after preparing the target single crystal silicon rod, the method further includes: obtaining an actual concentration variation curve of the dopant in the target single crystal silicon rod, and correcting the prediction model based on the actual concentration variation curve.

[0013] In some embodiments, the particle size of the dopant is 2 mm to 10 mm.

[0014] According to some embodiments of the present application, another aspect of the embodiments of the present application provides a silicon wafer, which is cut from a single crystal silicon rod, and the single crystal silicon rod is prepared by the method for preparing the single crystal silicon rod in the above embodiment.

[0015] The technical solution provided by the embodiments of the present application has at least the following advantages:

[0016] The method for preparing a single crystal silicon rod provided in an embodiment of the present application first prepares a test single crystal silicon rod, simulates an initial doping concentration model based on the process parameters and performance parameters of the test single crystal silicon rod, so as to characterize the change trend of the dopant concentration in the test single crystal silicon rod over time; further optimizes the initial doping concentration model according to the set target concentration range to obtain a prediction model, which can predict the change trend of the dopant concentration in the single crystal silicon rod over time when the dopant is added multiple times in the equal diameter process, and the prediction model includes multiple concentration inflection points and multiple supplementary doping time points, each supplementary doping time point corresponds to a concentration inflection point, so as to alleviate the problem of delayed change of the dopant concentration in the single crystal silicon rod after the addition of the dopant, which is conducive to keeping the dopant concentration in the single crystal silicon rod always between the first concentration and the second concentration; thereby, the target single crystal silicon rod actually prepared subsequently can better meet the target resistivity range, and improve the controllability of the resistivity uniformity of the single crystal silicon rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, the pictures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments are 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 work.

[0018] Figure 1 A flowchart corresponding to the method for manufacturing a single crystal silicon rod provided in an embodiment of the present application;

[0019] Figure 2 A predicted dopant concentration variation trend diagram of a single crystal silicon rod provided in an embodiment of the present application;

[0020] Figure 3 A schematic diagram of the structure of a supplementary doping device provided in an embodiment of the present application;

[0021] Figure 4A schematic diagram of the structure of a supplementary doping device provided in an embodiment of the present application applied in a single crystal furnace. DETAILED DESCRIPTION

[0022] The production process of single crystal silicon rods usually includes: melting process, seeding process, shoulder release process, shoulder rotation process, equal diameter process and finishing process. In the melting process, the polysilicon raw material and dopant need to be placed in a crucible for heating and melting; when the silicon material is completely melted and the melt is stable, the seed crystal is lowered for the seeding process; then the diameter of the single crystal silicon rod is enlarged to the target diameter through the shoulder release process; when the shoulder release diameter is close to the predetermined target diameter, the crystal pulling rate needs to be increased to perform the shoulder rotation process; in the equal diameter process, the single crystal silicon rod gradually enters the equal diameter growth state; after the single crystal silicon rod grows to the target length, the finishing process is performed.

[0023] Affected by the segregation coefficient and volatility of the dopant, the resistivity at different positions of the single crystal silicon rod is different, which leads to low resistivity uniformity of the single crystal silicon rod.

[0024] The embodiment of the present application provides a method for manufacturing a single crystal silicon rod, which is at least beneficial for controlling the resistivity uniformity of the single crystal silicon rod.

[0025] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0026] In the description of the embodiments of the present application, “plurality” means more than two, unless otherwise clearly and specifically defined.

[0027] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0028] The following will describe the various embodiments of the present application in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present application, many technical details are provided in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution claimed in the present application can be implemented.

[0029] Figure 1 This is a flow chart corresponding to the method for manufacturing a single crystal silicon rod provided in an embodiment of the present application.

[0030] refer to Figure 1 The method for manufacturing a single crystal silicon rod provided in an embodiment of the present application comprises:

[0031] S101: preparing a test single crystal silicon rod, and adding a dopant during the melting process of preparing the test single crystal silicon rod.

[0032] In the process of preparing the test single crystal silicon rod, a dopant is added in the melting process, wherein the dopant may be at least one of boron, phosphorus, arsenic or antimony.

[0033] S102: simulating an initial doping concentration model, where the initial doping concentration model is characterized by testing a change trend of the concentration of the dopant in the single crystal silicon rod over time in the equal diameter process.

[0034] According to the dopant concentration of the test single crystal silicon rod at different equal diameter lengths, the resistivity of the test single crystal silicon rod at the corresponding equal diameter length can be calculated. In the initial doping concentration model, the change trend of the dopant concentration of the test single crystal silicon rod over time can reflect the volatilization status of the dopant in the actual equal diameter process at different equal diameter lengths and the impact on the resistivity change of the initial single crystal silicon rod.

[0035] In some embodiments, the simulated initial doping concentration model may adopt a neural network model, for example, the neural network model includes a BP network (Back propagation network), a Hopfield network (Hopfield network), an ART network (Adaptive resonance theory network), an RBF network (Radial basis function network) or a self-organizing feature mapping network (Self-Organizing Feature Mapping), etc.

[0036] The simulation of the initial doping concentration model includes a data preparation step and a data training step. The data preparation step includes obtaining the production data in the initial single crystal silicon rod preparation step, and dividing the production data into training data and verification data. The production data includes but is not limited to the process parameters of the crystal pulling system and the performance parameters of the initial single crystal silicon rod. The production data can be the data of the crystal pulling system in the past period of time, for example, it can be the data generated in the past 3 months, 5 months or 10 months. The data training step uses the training data as the basic data for training the neural network model to learn the production mode of the crystal pulling system through the neural network model. The verification data can be used to verify the trained neural network model. The verification data is divided into an input part and a verification part. The data of the input part is input into the trained neural network model. If the overlap rate of the output result of the neural network model and the verification part is greater than or equal to 85%, for example, 85%, 88%, 90% or 100%, it is determined that the output result of the neural network model meets the requirements; otherwise, it is determined that the output result of the neural network model does not meet the requirements and needs to continue training.

[0037] The production data may also be real-time data generated when the crystal pulling system is running. The real-time data is input as an input parameter into the trained neural network model, and the output result of the neural network model is used as the prediction data.

[0038] S103: Setting a target concentration interval, wherein the minimum value of the target concentration interval is the first concentration, and the maximum value of the target concentration interval is the second concentration.

[0039] Since the concentration of the dopant in the single crystal silicon rod affects the resistivity of the single crystal silicon rod, the higher the concentration of the dopant in the single crystal silicon rod, the smaller the resistivity of the corresponding single crystal silicon rod; the lower the concentration of the dopant in the single crystal silicon rod, the larger the resistivity of the corresponding single crystal silicon rod. According to the required resistivity of the target single crystal silicon rod, a resistivity variation range that meets the requirements is set, and then the corresponding first concentration and second concentration of the dopant can be calculated respectively according to the maximum value and minimum value of the resistivity variation range.

[0040] S104: Optimizing the initial doping concentration model according to the target concentration range to obtain a prediction model, wherein the prediction model is characterized by, in the equal diameter process, when the dopant is added multiple times, the concentration of the dopant in the single crystal silicon rod changes with time, and the concentration of the dopant in the single crystal silicon rod is always between the first concentration and the second concentration. The prediction model includes multiple concentration inflection points and multiple supplementary doping time points, wherein the supplementary doping time point is the time point when the dopant is added, and the concentration inflection point is the time point when the dopant concentration in the single crystal silicon rod starts to increase or decrease after the dopant is added, and each supplementary doping time point corresponds to a concentration inflection point.

[0041] The initial doping concentration model obtained from the test single crystal silicon rod is the change trend of the dopant concentration in the single crystal silicon rod when no dopant is added. The initial doping concentration model is further optimized according to the target concentration range to obtain the change trend of the dopant concentration in the single crystal silicon rod when the dopant is added in the equal diameter process. On the one hand, multiple additions of dopants can help keep the concentration of the dopant in the single crystal silicon rod always between the first concentration and the second concentration. On the other hand, after the dopant is added, the dopant needs to be melted into the silicon melt first, and then enter the single crystal silicon rod through the length growth of the single crystal silicon rod. After the dopant is added, it takes a period of time to affect the dopant concentration in the single crystal silicon rod. Therefore, the prediction model also includes multiple concentration inflection points and multiple supplementary doping time points, and each supplementary doping time point corresponds to a concentration inflection point. This can alleviate the problem of delayed change of the dopant concentration in the single crystal silicon rod after the addition of dopants, thereby avoiding the dopant concentration in the single crystal silicon rod exceeding the target concentration range due to the hysteresis problem during the actual crystal pulling process.

[0042] In some embodiments, the types of dopants added multiple times may be the same or different.

[0043] In some embodiments, at each supplementary doping time point, the mass of the supplementary dopant is the same, and the time difference between any two supplementary doping time points may be different; in other embodiments, the time difference between any two consecutive supplementary doping time points is the same, and the mass of the supplementary dopant may be different at different supplementary doping time points. By adding the dopant at a fixed time or adding the dopant in a fixed amount, it is beneficial to improve the convenience of adding the dopant in the equal diameter process.

[0044] When the mass of the added dopant is the same at each supplementary doping time point, the initial doping concentration model is optimized according to the target concentration range to obtain a prediction model, including: calculating a preset supplementary doping amount based on the first concentration and the second concentration; obtaining the first time point when the concentration of the dopant in the test single crystal silicon rod reaches the first concentration or the second concentration for the first time in the initial doping concentration model; optimizing the initial doping concentration model for the first time in combination with the evaporation coefficient and segregation coefficient of the dopant and the preset supplementary doping amount, and repeatedly adjusting the first supplementary doping time point during the first optimization process so that the concentration inflection point is within the target concentration range; re-optimizing the previously optimized initial doping concentration model in chronological order, and adjusting the corresponding supplementary doping time points on the condition that the mass of the dopant added before the concentration of the dopant in the initial doping concentration model reaches the first concentration or the second concentration each time, so as to obtain a prediction model.

[0045] That is to say, a fixed preset supplementary doping dosage is first set, and the initial doping concentration model is adjusted according to the preset supplementary doping dosage and the evaporation coefficient and segregation coefficient of the dopant as variables, and the supplementary doping time point is adjusted according to the time point when the concentration of the dopant in the tested single crystal silicon rod reaches the first concentration or the second concentration, so that the concentration inflection point is within the target concentration range. The prediction model can predict the trend of the concentration change of the dopant in the process of the equal diameter process of the single crystal silicon rod, and when the same dosage of dopant is added at multiple supplementary doping time points set according to the prediction model, the dopant concentration change of the single crystal silicon rod is always within the range of the target concentration range, so that the resistivity change of the single crystal silicon rod is within the target range. In the subsequent actual preparation process of the target single crystal silicon rod, it is easier to obtain the target single crystal silicon rod that meets the target resistivity range, and improve the controllability of the resistivity uniformity of the single crystal silicon rod.

[0046] When the mass of the additional dopant is the same at each additional doping time point, the preset additional doping amount is greater than or equal to 1 / 3 of the difference between the second concentration and the first concentration, and less than or equal to 2 / 3 of the difference between the second concentration and the first concentration. Since a small amount of additional dopant does not significantly change the concentration of the dopant in the single crystal silicon rod, while a large amount of additional dopant is likely to cause the concentration of the dopant in the single crystal silicon rod to increase too much and exceed the target concentration range, the preset additional doping amount needs to be adjusted within a reasonable range.

[0047] When the time difference between any two consecutive supplementary doping time points is the same, the initial doping concentration model is optimized according to the target concentration range to obtain a prediction model, including: obtaining the first time point in the initial doping concentration model when the concentration of the dopant in the test single crystal silicon rod reaches the first concentration or the second concentration for the first time; calculating the first supplementary doping time point according to the first time point and the start time point of the equal diameter process, and the time difference between the first supplementary doping time point and the start time point of the equal diameter process is the supplementary doping time difference; optimizing the initial doping concentration model for the first time in combination with the first supplementary doping time point and the evaporation coefficient and segregation coefficient of the dopant, and in the process of the first optimization, repeatedly adjusting the mass of the first dopant so that the concentration inflection point is within the target concentration range; re-optimizing the initial doping concentration model optimized previously in chronological order, and adjusting the mass of the corresponding dopant on the condition that the time difference between the previous supplementary doping time point and the next supplementary doping time point is equal to the supplementary doping time difference, so as to obtain a prediction model.

[0048] That is to say, when the supplementary doping time difference is the time difference between the first supplementary doping time point and the start time point of the equal diameter process, the doping amount of each supplementary doping is adjusted so that the concentration inflection point is within the target concentration range. The prediction model can predict the trend of the concentration change of the dopant in the process of the equal diameter process of the single crystal silicon rod. When the supplementary doping time interval is set to be the same according to the prediction model, the dopant concentration change of the single crystal silicon rod is always kept within the range of the target concentration range, thereby making the resistivity change of the single crystal silicon rod within the target range. In the subsequent actual preparation process of the target single crystal silicon rod, it is easier to obtain the target single crystal silicon rod that meets the target resistivity range, thereby improving the controllability of the resistivity uniformity of the single crystal silicon rod.

[0049] When the time difference between any two supplementary doping time points is the same, the time difference between the first supplementary doping time point and the start time point of the equal diameter process is the initial time difference, and the supplementary doping time difference is greater than 1 / 3 of the initial time difference and less than 2 / 3 of the initial time difference. If the first supplementary doping time point is too early, it is easy to cause the concentration of the dopant in the single crystal silicon rod to exceed the target concentration range when the supplementary doping amount is small; if the first supplementary doping time point is too late, it is easy to cause the concentration of the dopant in the single crystal silicon rod to exceed the target concentration range due to the hysteresis problem when the supplementary doping amount is large. Therefore, the first supplementary doping time needs to be adjusted within a reasonable range.

[0050] S105: preparing a target single crystal silicon rod, and in the equal diameter process of preparing the target single crystal silicon rod, adding dopant according to the supplementary doping time point.

[0051] The prediction model can predict the trend of dopant concentration change of the single crystal silicon rod during the equal diameter process. According to the prediction model, the dopant concentration change of the single crystal silicon rod is always kept within the target concentration range when the dopant is added at a fixed time or in a quantitative manner. The resistivity change of the single crystal silicon rod is then kept within the target range. The target single crystal silicon rod actually prepared can better meet the target resistivity range, thereby improving the controllability of the resistivity uniformity of the single crystal silicon rod.

[0052] Figure 2 A predicted dopant concentration variation trend diagram of a single crystal silicon rod provided in an embodiment of the present application. Figure 2 Curve a in FIG. 1 represents the variation trend of the dopant concentration of the single crystal silicon rod without supplementary doping; Figure 2 Curve b in the figure represents the predicted change trend of the dopant concentration of the single crystal silicon rod in the case of multiple supplementary doping. The horizontal axis represents the solidification ratio, the vertical axis represents the concentration of the dopant in the single crystal silicon rod, and the solidification ratio represents the mass ratio of the solidified single crystal silicon rod to the total mass ratio of the initial silicon melt. As the solidification ratio increases, the equal diameter length of the single crystal silicon rod increases accordingly, and different solidification ratios correspond to different equal diameter lengths of the single crystal silicon rod.

[0053] refer to Figure 2 , taking the test of the concentration of dopants in the single crystal silicon rod gradually decreasing with the solidification ratio as an example, as the time of the equal diameter process increases, the time difference between different supplementary doping time points and the corresponding concentration inflection points gradually decreases. Due to the large amount of silicon melt in the early stage, the addition of supplementary dopants has little effect on the dopant concentration of the silicon melt, so the time interval between the supplementary doping time point and the concentration inflection point is small; as the equal diameter process proceeds, the amount of silicon melt decreases, and the addition of supplementary dopants has a more obvious effect on the dopant concentration of the silicon melt. In order to avoid a sudden change in the dopant concentration in the single crystal silicon rod, the time interval between the supplementary doping time point and the concentration inflection point gradually increases.

[0054] It should be noted that in Figure 2 In the example, the concentration of the dopant in the test single crystal silicon rod gradually decreases with the solidification ratio, and at each supplementary doping time point, the concentration of the dopant in the single crystal silicon rod increases after the dopant is added. In other embodiments, with the influence of the evaporation coefficient and segregation coefficient of the dopant, the concentration of the dopant in the test single crystal silicon rod can gradually increase or first increase and then decrease, etc., and after the dopant is added, the concentration of the dopant in the single crystal silicon rod can increase or decrease. Those skilled in the art can set the type of dopant to be added at different supplementary doping time points according to the concentration change trend of the test single crystal silicon rod combined with the evaporation coefficient and segregation coefficient of the dopant, and set the timed or quantitative supplementary doping in combination with the method for manufacturing the single crystal silicon rod provided in the embodiment of the present application, so that the dopant concentration of the single crystal silicon rod in the prediction model is always within the target concentration range, so as to improve the resistivity uniformity of the single crystal silicon rod actually prepared.

[0055] In some embodiments, after preparing the target single crystal silicon rod, the method further includes: obtaining an actual concentration variation curve of the dopant in the target single crystal silicon rod, and correcting the prediction model based on the actual concentration variation curve. That is, after multiple supplementary doping according to the parameters in the prediction model, the target single crystal silicon rod actually obtained can be used to verify the accuracy of the prediction model, and correcting the prediction model based on the actual concentration variation curve can be more conducive to controlling the uniformity of the resistivity of the target single crystal silicon rod prepared next time.

[0056] In some embodiments, the particle size of the dopant is 2 mm to 10 mm, and the particle size refers to the width range of a single dopant passing through the center of gravity, for example, it can be 2 mm, 4 mm, 6 mm, 8 mm or 10 mm. The particle size of the dopant affects the speed at which the dopant melts in the silicon melt. The particle size of the dopant needs to be within an appropriate range to reduce the impact on the dopant concentration in the single crystal silicon rod.

[0057] The method for preparing a single crystal silicon rod provided in an embodiment of the present application first prepares a test single crystal silicon rod, simulates an initial doping concentration model based on the process parameters and performance parameters of the test single crystal silicon rod, so as to characterize the change trend of the dopant concentration in the test single crystal silicon rod over time; further optimizes the initial doping concentration model according to the set target concentration range to obtain a prediction model, which can predict the change trend of the dopant concentration in the single crystal silicon rod over time when the dopant is added multiple times in the equal diameter process, and the prediction model includes multiple concentration inflection points and multiple supplementary doping time points, each supplementary doping time point corresponds to a concentration inflection point, so as to alleviate the problem of delayed change of the dopant concentration in the single crystal silicon rod after the addition of the dopant, which is conducive to keeping the dopant concentration in the single crystal silicon rod always between the first concentration and the second concentration; thereby, the target single crystal silicon rod actually prepared subsequently can better meet the target resistivity range, and improve the controllability of the resistivity uniformity of the single crystal silicon rod.

[0058] According to some embodiments of the present application, another aspect of the embodiments of the present application provides a silicon wafer, which is cut from a single crystal silicon rod, and the single crystal silicon rod is prepared by the method for preparing the single crystal silicon rod in the above embodiment.

[0059] According to some embodiments of the present application, another aspect of the embodiments of the present application further provides a supplementary doping device, which is applied to the above-mentioned method for preparing the single crystal silicon rod, so as to facilitate the addition of dopants in the equal diameter process of the single crystal silicon rod.

[0060] Figure 3 A schematic diagram of the structure of a supplementary doping device provided in an embodiment of the present application; Figure 4 A schematic diagram of the structure of a supplementary doping device provided in an embodiment of the present application applied in a single crystal furnace.

[0061] refer to Figure 3 and Figure 4 The supplementary doping device 200 includes: a housing 201, a feeding pipe 202, a dopant storage 203 and a dopant dispenser 204. The feeding pipe 202 runs through the housing 201 along the length direction of the housing 202; the dopant storage 203 is located at one end of the housing 201; and the dopant dispenser 204 is connected between the feeding pipe 202 and the dopant dispenser 204. The dopant storage 203 can control the mass of the dopant falling into the dopant dispenser 204. After the dopant falls into the dopant dispenser 204, the dopant delivery time point can be controlled by the dopant dispenser 204. After the dopant dispenser 204 is turned on at the supplementary doping time point, the dopant falls into the crucible through the feeding pipe 202.

[0062] In some embodiments, the material of the feeding tube 202 is quartz glass.

[0063] In some embodiments, the surface of the shell 201 away from the dopant storage 203 has a protective layer 205, and the material of the protective layer 205 includes inorganic materials, organic materials or nano materials, etc. The inorganic materials include ceramic materials, silicates or phosphates, etc.; the organic materials include silicone resin materials or fluororesin materials, etc.

[0064] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present application, and in practical applications, various changes may be made to the embodiments in form and detail without departing from the spirit and scope of the present application. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application, and therefore the scope of protection of the present application shall be subject to the scope defined in the claims.

Claims

1. A method for manufacturing a single crystal silicon rod, characterized in that: include: preparing a test single crystal silicon rod, and adding a dopant during a melting process of preparing the test single crystal silicon rod; Simulating an initial doping concentration model, wherein the initial doping concentration model is characterized by a change trend of the concentration of the dopant in the test single crystal silicon rod over time in a constant diameter process; Setting a target concentration interval, wherein the minimum value of the target concentration interval is a first concentration and the maximum value of the target concentration interval is a second concentration; The initial doping concentration model is optimized according to the target concentration range to obtain a prediction model, wherein the prediction model is characterized by a change trend of the concentration of the dopant in the single crystal silicon rod over time when the dopant is added multiple times in the equal diameter process, and the concentration of the dopant in the single crystal silicon rod is always between the first concentration and the second concentration, and the prediction model includes a plurality of concentration inflection points and a plurality of supplementary doping time points, wherein the supplementary doping time point is a time point at which the dopant is added, and the concentration inflection point is a time point at which the concentration of the dopant in the single crystal silicon rod begins to increase or decrease after the dopant is added, and each of the supplementary doping time points corresponds to a concentration inflection point prior to the addition of the dopant; A target single crystal silicon rod is prepared, and in a process of equalizing the diameter of the target single crystal silicon rod, dopants are added according to the supplementary doping time point.

2. The method for manufacturing a single crystal silicon rod according to claim 1, characterized in that: At each of the supplementary doping time points, the mass of the supplementary dopant is the same; or the time difference between any two consecutive supplementary doping time points is the same.

3. The method for manufacturing a single crystal silicon rod according to claim 2, characterized in that: At each time point of the supplementary doping, the mass of the supplementary dopant is the same, and the initial doping concentration model is optimized according to the target concentration range to obtain the prediction model, including: Calculating a preset supplementary doping amount based on the first concentration and the second concentration; Obtaining a first time point when the concentration of the dopant in the test single crystal silicon rod reaches the first concentration or the second concentration for the first time in the initial doping concentration model; The initial doping concentration model is optimized for the first time in combination with the evaporation coefficient and the segregation coefficient of the dopant and the preset supplementary doping amount. During the first optimization, the first supplementary doping time point is repeatedly adjusted so that the concentration inflection point is within the target concentration range. The previously optimized initial doping concentration model is optimized again in chronological order, and the corresponding supplementary doping time points are adjusted on the condition that the mass of the dopant added before the concentration of the dopant in the initial doping concentration model reaches the first concentration or the second concentration each time, so as to obtain the prediction model.

4. The method for manufacturing a single crystal silicon rod according to claim 3, characterized in that: The preset supplementary doping amount is greater than or equal to 1 / 3 of the difference between the second concentration and the first concentration, and less than or equal to 2 / 3 of the difference between the second concentration and the first concentration.

5. The method for manufacturing a single crystal silicon rod according to claim 2, characterized in that: The time difference between any two consecutive supplementary doping time points is the same, and the initial doping concentration model is optimized according to the target concentration range to obtain the prediction model, including: Obtaining a first time point when the concentration of the dopant in the test single crystal silicon rod reaches the first concentration or the second concentration for the first time in the initial doping concentration model; Calculating the first supplementary doping time point according to the first time point and the starting time point of the equal diameter process, the time difference between the first supplementary doping time point and the starting time point of the equal diameter process is the supplementary doping time difference; The initial doping concentration model is optimized for the first time in combination with the first supplementary doping time point and the evaporation coefficient and segregation coefficient of the dopant, and during the first optimization process, the mass of the first dopant is repeatedly adjusted so that the concentration inflection point is within the target concentration range; The previously optimized initial doping concentration model is optimized again in chronological order, and the quality of the corresponding dopant is adjusted under the condition that the time difference between the previous supplementary doping time point and the next supplementary doping time point is equal to the supplementary doping time difference to obtain the prediction model.

6. The method for manufacturing a single crystal silicon rod according to claim 5, characterized in that: The time difference between the first supplementary doping time point and the start time point of the equal diameter process is the initial time difference, and the supplementary doping time difference is greater than 1 / 3 of the initial time difference and less than 2 / 3 of the initial time difference.

7. The method for manufacturing a single crystal silicon rod according to claim 1, characterized in that: As the time of the equal diameter process increases, the time difference between the different supplementary doping time points and the corresponding concentration inflection points gradually decreases.

8. The method for manufacturing a single crystal silicon rod according to claim 1, characterized in that: After preparing the target single crystal silicon rod, the method further includes: obtaining an actual concentration variation curve of the dopant in the target single crystal silicon rod, and correcting the prediction model based on the actual concentration variation curve.

9. The method for manufacturing a single crystal silicon rod according to claim 1, characterized in that: The particle size of the dopant is 2 mm to 10 mm.

10. A silicon wafer, characterized in that: The silicon slices are cut from single crystal silicon rods, and the single crystal silicon rods are prepared by the method for preparing single crystal silicon rods according to any one of claims 1 to 9.

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