Preparation method of silicon single crystal rod and silicon wafer

Abstract

The embodiment of the invention relates to the field of semiconductor manufacturing, and provides a preparation method of a silicon single crystal rod and a silicon wafer. The preparation method of the silicon single crystal rod comprises the following steps: establishing a first corresponding relationship, wherein the first corresponding relationship is a corresponding relationship between the equal-diameter length of the silicon single crystal rod and evaporation parameters of a dopant in a crucible in a historical preparation process; according to the first corresponding relation, the segmentation principle of the single crystal silicon rod in the equal-diameter process is determined, the segmentation principle comprises a plurality of equal-diameter stages and equal-diameter length ranges corresponding to the equal-diameter stages, and the equal-diameter stages comprise the equal-diameter initial stage, the equal-diameter middle stage and the equal-diameter later stage; according to the segmentation principle and the actual equal-diameter length of the single crystal silicon rod in the current preparation process, the current equal-diameter stage of the single crystal silicon rod is determined; and according to the current equal-diameter stage of the single crystal silicon rod, controlling the growth of the single crystal silicon rod by adopting a control strategy corresponding to the current equal-diameter stage. According to the invention, the problem that the single crystal silicon rod is easy to break in the equal-diameter growth process is solved.

Description

TECHNICAL FIELD

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

[0002] In the Czochralski (CZ) growth process, the constant diameter growth stage is one of the key steps in the production of single crystal silicon rods. The goal of this stage is to maintain the diameter of the growing single crystal silicon rod within the specified range while ensuring the quality of the crystal, usually requiring a minimal deviation between the crystal diameter and the target diameter.

[0003] The problem of broken lines (or broken petals) has always been a key factor affecting production efficiency and crystal quality. Broken lines (or broken petals) during the constant diameter growth stage refer to the interruption of crystal growth due to various factors during this process, which not only reduces production efficiency, but also affects the quality of the crystal, causing material waste and increased costs. SUMMARY

[0004] The present application provides a method for preparing a single crystal silicon rod and a silicon wafer, which at least solves the problem of broken lines of the single crystal silicon rod during the constant diameter growth process in the prior art.

[0005] According to some embodiments of the present application, the present application provides a method for preparing a single crystal silicon rod, comprising: establishing a first correspondence relationship between the constant diameter length of a single crystal silicon rod in a historical preparation process and the evaporation parameters of a dopant in a crucible; determining a segmentation principle for the single crystal silicon rod during the constant diameter process according to the first correspondence relationship, the segmentation principle including a plurality of constant diameter stages and the corresponding constant diameter length range of each constant diameter stage, the plurality of constant diameter stages including an early constant diameter stage, a middle constant diameter stage, and a late constant diameter stage; determining the current constant diameter stage of the single crystal silicon rod according to the segmentation principle and the actual constant diameter length of the single crystal silicon rod in the current preparation process; and controlling the growth of the single crystal silicon rod according to the current constant diameter stage of the single crystal silicon rod using the control strategy corresponding to the current constant diameter stage.

[0006] In some embodiments, the establishing the first correspondence relationship comprises: obtaining a second correspondence relationship and a third correspondence relationship, the second correspondence relationship being a correspondence relationship between a first resistivity of the single crystal silicon rod and the constant diameter length, the first resistivity being a resistivity of the single crystal silicon rod only considering a segregation behavior of the dopant, the third correspondence relationship being a correspondence relationship between a second resistivity of the single crystal silicon rod and the constant diameter length in the historical preparation process, the second resistivity being a measured resistivity of the single crystal silicon rod considering the segregation behavior and an evaporation behavior of the dopant; and determining the first correspondence relationship according to the second correspondence relationship and the third correspondence relationship.

[0007] In some embodiments, the determining the first correspondence relationship according to the second correspondence relationship and the third correspondence relationship comprises: calculating a change of a difference between the second resistivity and the first resistivity with the constant diameter length according to the second correspondence relationship and the third correspondence relationship; and converting the difference between the second resistivity and the first resistivity into an evaporation amount and / or an evaporation constant of the dopant to obtain the first correspondence relationship representing a change of the evaporation amount and / or the evaporation constant with the constant diameter length.

[0008] In some embodiments, the determining the segmentation principle of the single crystal silicon rod in the constant diameter process according to the first correspondence relationship comprises: determining, according to a maximum value of the evaporation parameter in the first correspondence relationship, that the constant diameter middle stage corresponds to a constant diameter length range of [a first length, a second length], the first length being a constant diameter length corresponding to a difference between the maximum value and a predetermined percentage of the maximum value in the first correspondence relationship, the second length being a constant diameter length corresponding to a sum of the maximum value and the predetermined percentage of the maximum value in the first correspondence relationship, the predetermined percentage being in a range of 5% to 15%; determining, according to the first length, that the constant diameter early stage corresponds to a constant diameter length range less than the first length; and determining, according to the second length and a maximum constant diameter length in the first correspondence relationship, that the constant diameter late stage corresponds to a constant diameter length range of (the second length, the maximum constant diameter length].

[0009] In some embodiments, according to the first correspondence relationship, the segmentation principle of the single crystal silicon rod in the constant diameter process is determined, including: calculating the evaporation parameter change rate in the first correspondence relationship, determining that the constant diameter length corresponding to the evaporation parameter change rate with an absolute value less than or equal to 5e18 is the constant diameter length range corresponding to the middle stage of the constant diameter; determining that the constant diameter length range corresponding to the early stage of the constant diameter is less than a third length, the third length being the minimum value of the constant diameter length range corresponding to the middle stage of the constant diameter; determining that the constant diameter length range corresponding to the late stage of the constant diameter is greater than a fourth length and less than or equal to the maximum constant diameter length in the first correspondence relationship, the fourth length being the maximum value of the constant diameter length range corresponding to the middle stage of the constant diameter.

[0010] In some embodiments, according to the current constant diameter stage of the single crystal silicon rod, a control strategy corresponding to the current constant diameter stage is used to control the growth of the single crystal silicon rod, including: in the case that the current constant diameter stage is the early stage of the constant diameter, at least controlling the heating power of the heater of the crucible to decrease with the increase of the constant diameter length; in the case that the current constant diameter stage is the middle stage of the constant diameter, adjusting the crystal transition speed of the single crystal silicon rod according to the fluctuation of the pulling speed of the single crystal silicon rod; in the case that the current constant diameter stage is the late stage of the constant diameter, adjusting the heating power according to the heating power fluctuation of the middle stage of the constant diameter relative to the early stage of the constant diameter.

[0011] In some embodiments, the crystal transition speed of the single crystal silicon rod is adjusted according to the fluctuation of the pulling speed of the single crystal silicon rod, including: in the case that the change rate of the pulling speed is greater than a predetermined threshold, uniformly reducing the crystal transition speed at a predetermined frequency; in the case that the change rate of the pulling speed is less than or equal to the predetermined threshold, uniformly increasing the crystal transition speed at the predetermined frequency.

[0012] In some embodiments, the heating power is adjusted according to the heating power fluctuation of the middle stage of the constant diameter relative to the early stage of the constant diameter, including: in the case that the heating power change rate of the middle stage of the constant diameter relative to the early stage of the constant diameter satisfies (0, 2%], controlling the heater to work at a set power; in the case that the heating power change rate satisfies (2%, 5%], controlling the heater to work at a first multiple of the set power, the first multiple being greater than 1; in the case that the heating power change rate is greater than 5%, controlling the heater to work at a second multiple of the set power, the second multiple being greater than the first multiple.

[0013] In some embodiments, the control of the heating power of the heater of the crucible decreases with the increase of the constant diameter length, including: keeping the control of the meniscus length of the single crystal silicon rod unchanged, and controlling the heating power of the heater of the crucible to decrease with the increase of the constant diameter length.

[0014] According to some embodiments of the present application, another aspect of the embodiments of the present application provides a silicon wafer obtained by cutting a single crystal silicon rod, wherein the single crystal silicon rod is prepared by any one of the methods for preparing a single crystal silicon rod, and the single crystal silicon rod has a wire breakage rate of less than or equal to 0.2 during the constant diameter process.

[0015] The technical solutions provided by the embodiments of the present application have at least the following advantages: in the method for preparing a single crystal silicon rod, a first correspondence relationship between the constant diameter length of the single crystal silicon rod and the evaporation parameters of the dopant is first established; then, according to the first correspondence relationship, a segmentation principle including the constant diameter stage and the corresponding constant diameter length range is determined; then, according to the segmentation principle and the actual constant diameter length of the single crystal silicon rod, the constant diameter stage currently occupied by the single crystal silicon rod is determined; finally, a control strategy suitable for the constant diameter stage currently occupied by the single crystal silicon rod is used to control the growth of the single crystal silicon rod in the constant diameter stage. According to the correspondence relationship between the constant diameter length and the evaporation parameters of the dopant, the constant diameter stage is segmented. Since the evaporation parameters of the dopant are directly related to the thermal equilibrium state, the segmentation principle of the constant diameter stage is more scientific and reasonable, avoiding the subjectivity of artificially and empirically segmenting the constant diameter stage. The corresponding control strategy is executed in each constant diameter stage to control the growth of the single crystal silicon rod, ensuring that the growth of the single crystal silicon rod in each constant diameter stage is stable and controllable, thereby reducing the wire breakage rate of the single crystal silicon rod in the constant diameter process, reducing the production cost of the single crystal silicon rod, and improving the material utilization rate in the growth process of the single crystal silicon rod. BRIEF DESCRIPTION OF DRAWINGS

[0016] One or more embodiments are illustrated by way of example in the figures that form a part of this disclosure and which are shown by way of illustration in the drawings. Together with the description, the drawings serve to explain principles of embodiments. In the drawings:

[0017] Figure 1 A flowchart of a method for preparing a single crystal silicon rod according to an embodiment of the present application is shown in FIG. 1.

[0018] Figure 2A single crystal silicon rod in each constant diameter stage before and after the embodiment of the present application provides a broken line rate comparison chart of the single crystal silicon rod in each constant diameter stage;

[0019] Figure 3 A schematic diagram of the corresponding relationship between the constant diameter length and the resistivity of the single crystal silicon rod in the embodiment of the present application is provided;

[0020] Figure 4 A corresponding relationship diagram between the constant diameter length and the evaporation of the single crystal silicon rod in the embodiment of the present application is provided;

[0021] Figure 5 A corresponding relationship diagram between the constant diameter length and the evaporation constant of the single crystal silicon rod in the embodiment of the present application is provided;

[0022] Figure 6 A corresponding relationship diagram between the constant diameter length and the evaporation amount of the single crystal silicon rod in the embodiment of the present application is provided. DETAILED DESCRIPTION

[0023] As can be known from the background art, the current often relies on the experience of the operator, and the initial stage, the middle stage and the late stage of the constant diameter growth are artificially divided, which causes the unreasonable process control of the single crystal silicon rod in different constant diameter growth stages, and the single crystal silicon rod is prone to broken line.

[0024] Based on the technical problem, the embodiment of the present application provides a single crystal silicon rod preparation method and a silicon wafer. The single crystal silicon rod preparation method comprises: establishing a first corresponding relationship, the first corresponding relationship is a corresponding relationship between the constant diameter length of the single crystal silicon rod in the historical preparation process and the evaporation parameter of the dopant in the crucible; determining the segmentation principle of the single crystal silicon rod in the constant diameter process according to the first corresponding relationship, the segmentation principle comprises a plurality of constant diameter stages and the constant diameter length range corresponding to each constant diameter stage, and the plurality of constant diameter stages comprise the initial stage, the middle stage and the late stage of the constant diameter; determining the current constant diameter stage of the single crystal silicon rod according to the segmentation principle and the actual constant diameter length of the single crystal silicon rod in the current preparation process; and controlling the growth of the single crystal silicon rod according to the current constant diameter stage of the single crystal silicon rod by using the control strategy corresponding to the current constant diameter stage.

[0025] In the description of the embodiments of the present application, the technical terms "first", "second" and the like 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. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0026] Reference to“an embodiment” herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase“in an embodiment” in various places in the specification are not necessarily referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. As will be apparent to those of ordinary skill in the art, embodiments described herein can be combined with other embodiments.

[0027] In the description of the embodiments of the application, the term“and / or” is merely an association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of existence of A, existence of A and B, and existence of B. In addition, the character“ / ” herein generally represents an“or” relationship between the front and rear associated objects.

[0028] In the description of the embodiments of the application, the term“a plurality of” refers to two or more (including two), and similarly, “a plurality of groups” refers to two or more groups (including two groups), and “a plurality of pieces” refers to two or more pieces (including two pieces).

[0029] In the description of the embodiments of the application, the technical terms“center”,“longitudinal”,“transverse”,“length”,“width”,“thickness”,“upper”,“lower”,“front”,“rear”,“left”,“right”,“vertical”,“horizontal”,“top”,“bottom”,“inner”,“outer”,“clockwise”,“counterclockwise”,“axial”,“radial”,“circumferential” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the application.

[0030] In the description of the embodiments of the application, unless otherwise explicitly specified and limited, the technical terms“mounting”,“connection”,“connection”,“fixing” and the like should be understood broadly, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meaning of the terms in the embodiments of the application can be understood according to the specific circumstances.

[0031] In the drawings corresponding to the embodiments of the present application, the thickness and area of a layer are exaggerated for clarity and ease of description. When a component (such as a layer, film, region, or substrate) is described as being "on" or "at" another component, it can be "directly on" the other component (i.e., located between the other component and no other component) or there can be a third component between the two components. Conversely, when a component is described as being "formed on" or "formed at" another component, it is meant that there are no third components between the two components. In addition, when a component is described as being "formed substantially on" another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a partial edge of the entire surface.

[0032] In the description of the embodiments of the present application, when a component "includes" another component, unless otherwise specified, other components can also be included, and other components can also be further included. In addition, when a layer, film, region, or plate, and the like, is referred to as "on / over" another component, it can be "directly on" the other component (i.e., located between the other component and no other component), or there can be another component therebetween. In addition, when a layer, film, region, plate, and the like, is "directly on" another component, or when a layer, film, region, plate, and the like, is on the surface of another component, it is meant that there are no other components therebetween.

[0033] The terms used in the description of various described embodiments herein are for the purpose of describing particular embodiments only and are not intended to be limiting. As used in the description of various embodiments described and the appended claims, "the part" is also intended to include the plural, unless the context clearly indicates otherwise. Among them, the components include layers, films, regions, or plates, and the like.

[0034] The embodiments of the present application will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art can understand that in the embodiments of the present application, many technical details are presented in order to enable the reader to better understand the present application. However, the technical solutions claimed by the present application can be implemented even without these technical details and based on various changes and modifications of the following embodiments.

[0035] The embodiments of the present application provide, on the one hand, a method for preparing a single crystal silicon rod, Figure 1 is a flowchart of the method for preparing a single crystal silicon rod according to the embodiments of the present application. As Figure 1 indicated, the method includes the following steps:

[0036] Step S201, a first correspondence relationship is established, the first correspondence relationship is the correspondence relationship between the constant diameter length of the single crystal silicon rod in the historical preparation process and the evaporation parameter of the dopant in the crucible;

[0037] Specifically, by the dopant, specific impurity atoms are introduced into the silicon lattice to change the conductivity type and / or resistivity of the silicon to meet the device requirements. The evaporation parameter refers to the evaporation behavior of the dopant during the growth of the single crystal silicon rod. The evaporation parameter can include at least one of the evaporation amount and the evaporation constant.

[0038] In step S202, according to the first correspondence, a segmentation principle of the single crystal silicon rod in the constant diameter process is determined, the segmentation principle including a plurality of constant diameter stages and a constant diameter length range corresponding to each of the constant diameter stages, the plurality of constant diameter stages including a constant diameter early stage, a constant diameter middle stage and a constant diameter late stage.

[0039] Optionally, the constant diameter early stage can be a transition period from the end of the shoulder (the crystal diameter of the single crystal silicon rod reaches the target value) to the complete stabilization of the diameter (the error of the crystal diameter with the target value is less than a very small threshold value); the constant diameter middle stage can be a main growth stage of the constant diameter growth after the complete stabilization of the diameter; the constant diameter late stage can be a stage where the constant diameter growth is close to the end and the remaining amount of the melt is small (usually less than 20% to 30% of the initial melt). Optionally, the segmentation principle can be composed of the constant diameter early stage and the corresponding constant diameter length range, the constant diameter middle stage and the corresponding constant diameter length range, and the constant diameter late stage and the corresponding constant diameter length range.

[0040] In step S203, according to the segmentation principle and the actual constant diameter length of the single crystal silicon rod in the current preparation process, a current constant diameter stage of the single crystal silicon rod is determined.

[0041] Specifically, the actual constant diameter length refers to the length of the crystal actually grown in the constant diameter stage, and the current constant diameter stage refers to the constant diameter stage corresponding to the actual constant diameter length. Optionally, according to the actual constant diameter length of the single crystal silicon rod, the constant diameter length range in which the actual constant diameter length is located is determined from the segmentation principle, and the constant diameter stage corresponding to the constant diameter length range is the current constant diameter stage.

[0042] In step S204, according to the current constant diameter stage of the single crystal silicon rod, a control strategy corresponding to the current constant diameter stage is used to control the growth of the single crystal silicon rod.

[0043] Optionally, the control strategies corresponding to any two of the constant diameter stages are different.

[0044] By the embodiment, firstly, a first correspondence between the constant diameter length of a single crystal silicon rod and the evaporation parameter of a dopant is established; then, according to the first correspondence, a segmentation principle including a constant diameter stage and a corresponding constant diameter length range is determined; then, according to the segmentation principle and the actual constant diameter length of the single crystal silicon rod, a constant diameter stage currently occupied by the single crystal silicon rod is determined; finally, a control strategy adapted to the constant diameter stage currently occupied is used to control the growth of the single crystal silicon rod in the constant diameter stage. According to the correspondence between the constant diameter length and the evaporation parameter of the dopant, the constant diameter stage is segmented. Since the evaporation parameter of the dopant is directly related to the thermal equilibrium state, the segmentation principle of the constant diameter stage is more scientific and reasonable, avoiding the subjectivity of artificially and empirically segmenting the constant diameter stage. The corresponding control strategy is executed in each constant diameter stage to control the growth of the single crystal silicon rod, ensuring that the growth of the single crystal silicon rod in each constant diameter stage is more stable and controllable, thereby reducing the breakage rate of the single crystal silicon rod during the constant diameter process, reducing the production cost of the single crystal silicon rod, and improving the material utilization rate during the growth of the single crystal silicon rod.

[0045] Specifically, in the growth process of a single crystal silicon rod crystal, the growth interface needs to be stable and the temperature needs to be constant to efficiently grow high-quality crystals. In the Czochralski crystal growth process, the heat sources in the temperature system are mainly the heater and the release of crystallization latent heat during crystallization. The constant diameter growth process needs to control the changes of the two heat sources and the dynamic system balance of heat dissipation. The process is divided into three stages in the application:

[0046] Stage one, early constant diameter: the crystallization rate of the crystal slowly increases, accompanied by the rise of crystallization latent heat. The system changes from a binary balance of the heater and dissipation to a ternary system of the heater, crystallization latent heat and dissipation. To ensure the dynamic balance of the heat system, the heater power needs to be slowly decreased, i.e., ΔE heater + ΔE crystallization latent heat > ΔE dissipation;

[0047] Stage two, middle constant diameter: with the decrease of the heater power, ΔE heater = ΔE crystallization latent heat is reached, and ΔE heater + ΔE crystallization latent heat = ΔE dissipation is satisfied, then the system enters a balanced state, at which the crystal can grow stably with high quality;

[0048] Stage three, late constant diameter: with the increase of the crystal length, the crystal surface area continuously increases, resulting in the increase of ΔE dissipation ability, i.e., ΔE heater + ΔE crystallization latent heat < ΔE dissipation. At this time, to ensure the dynamic balance of the heat system, the power of the heater must be increased to balance the dissipation.

[0049] It should be noted that since the evaporation of the dopant occurs at the free surface of the melt, the evaporation interface and the growth interface are basically at the same level, so when the equal-diameter power, furnace pressure and other variables are constant, the change of the evaporation parameters (such as the evaporation amount) can directly reflect the change of the melt temperature. Therefore, the evaporation parameters of the dopant can directly reflect the thermal equilibrium state of the single crystal silicon rod during the equal-diameter process. According to the change of the ΔE heater (directly acting on the melt) in the three stages in the crystal growth principle, the equal-diameter length range can be segmented.

[0050] In a specific application process, the dopant can include at least one of phosphorus, arsenic and antimony.

[0051] In some optional solutions, establishing the first correspondence relationship includes: obtaining a second correspondence relationship and a third correspondence relationship, the second correspondence relationship being a simulated correspondence relationship between a first resistivity of the single crystal silicon rod and the equal-diameter length, and the third correspondence relationship being a correspondence relationship between a second resistivity of the single crystal silicon rod and the equal-diameter length in the historical preparation process, wherein the first resistivity is the resistivity of the single crystal silicon rod only considering the segregation behavior of the dopant, and the second resistivity is the measured resistivity of the single crystal silicon rod considering the segregation behavior and the evaporation behavior of the dopant; and determining the first correspondence relationship according to the second correspondence relationship and the third correspondence relationship.

[0052] In the embodiments, the evaporation parameters of the dopant are indirectly reflected by the change of the resistivity, and considering that the segregation behavior and the evaporation behavior will both affect the resistivity of the single crystal silicon rod, the correspondence relationship between the equal-diameter length and the resistivity corresponding to the segregation behavior of the dopant is established, and the correspondence relationship between the equal-diameter length and the resistivity corresponding to the segregation behavior + evaporation behavior of the dopant is also established, and then according to the two relationships, the accurate correspondence relationship between the equal-diameter length and the evaporation parameters of the dopant can be obtained, which provides a quantitative basis for the segmentation in the equal-diameter process, so that the process parameters can be adjusted according to the equal-diameter stage, the equal-diameter growth process of the single crystal silicon rod can be effectively controlled and optimized, the production cost can be reduced, the crystal quality can be improved, and the occurrence of wire breakage can be reduced.

[0053] Exemplarily, the resistivity of the single crystal silicon rod under different equal-diameter lengths is obtained by simulation test only considering the segregation behavior of the dopant.

[0054] Exemplarily, after the surface oxide layer of the single crystal silicon rod is removed and polished flat, the resistivity of the single crystal silicon rod is measured using a portable four-probe, and the resistivity corresponding to different equal-diameter lengths is obtained. Specifically, the resistivity is measured at every 120° of the circumference of the single crystal silicon rod, and the resistivity of three points on the circumference is repeatedly measured every 50 mm in the axial direction.

[0055] In some embodiments of the present application, the first corresponding relationship is determined according to the second corresponding relationship and the third corresponding relationship, including: calculating the change of the difference between the second resistivity and the first resistivity with the equal-diameter length according to the second corresponding relationship and the third corresponding relationship; and converting the difference between the second resistivity and the first resistivity into the evaporation amount and / or evaporation constant of the dopant to obtain the first corresponding relationship representing the change of the evaporation amount and / or evaporation constant with the equal-diameter length. In this embodiment, by calculating the change of the difference between the second resistivity and the first resistivity with the equal-diameter length, the influence of the segregation behavior on the resistivity can be eliminated, and the change of the resistivity affected only by the evaporation behavior with the equal-diameter length is obtained. Then, the resistivity is converted into the evaporation amount and / or evaporation constant, and the first corresponding relationship representing the change trend of the evaporation amount and / or evaporation constant with the equal-diameter length is obtained, which further ensures that a more accurate first corresponding relationship can be obtained.

[0056] Exemplarily, the resistivity can be converted into the concentration according to the content of GBT 13389-2014 Conversion of Resistivity to Doping Concentration for Boron, Phosphorus and Arsenic Doped Silicon Single Crystals. Specifically, the specific process of converting the difference between the second resistivity and the first resistivity into the evaporation amount and / or evaporation constant of the dopant is as follows: the doping concentration corresponding to the first resistivity and the doping concentration corresponding to the second resistivity are calculated according to the formula for converting the resistivity to the doping concentration in the single crystal silicon:

[0057]

[0058] In the formula, ρ is the resistivity, unit: Ω·cm, N D is the doping concentration, unit: cm- 3 ,

[0059] x = lgρ; A0 = -3.1083; A1 = -3.2626; A2 = -1.2196; A3 = -0.13923; B1 = 1.0265; B2 = 0.38755; B3 = 0.041833.

[0060] The difference between the two doping concentrations obtained above is multiplied by the volume of the single crystal silicon rod per unit length to obtain the evaporation amount.

[0061] Then, the evaporation constant is calculated according to the evaporation amount, and the specific formula is as follows:

[0062] The concentration formula after evaporation is C=C0e^-(Ev*A / W);

[0063] The evaporation amount formula is N=(C0-C)*V;

[0064] In the above formula, C is the concentration after time t; C0 is the initial concentration of impurities; A is the evaporation surface area of the melt; Ev is the evaporation rate constant of impurities cm / s; W is the mass (weight) of molten silicon; and V is the excess material volume cm 3 The evaporation constant Ev can be obtained by substituting the evaporation amount into the above formula.

[0065] According to some embodiments of the present application, according to the first correspondence relationship, the segmentation principle of the single crystal silicon rod in the equal diameter process is determined, including: according to the maximum value of the evaporation parameter in the first correspondence relationship, determining that the equal diameter middle period corresponds to the equal diameter length range [first length, second length], the first length is the equal diameter length corresponding to the difference between the maximum value and the predetermined percentage of the maximum value in the first correspondence relationship, the second length is the equal diameter length corresponding to the sum of the maximum value and the predetermined percentage of the maximum value in the first correspondence relationship, and the predetermined percentage ranges from 5% to 15%; according to the first length, determining that the equal diameter early period corresponds to the equal diameter length range less than the first length; and according to the second length and the maximum equal diameter length in the first correspondence relationship, determining that the equal diameter late period corresponds to the equal diameter length range [second length, maximum equal diameter length].

[0066] In the embodiments, the equal diameter length corresponding to the equal diameter middle period, the equal diameter early period and the equal diameter late period is determined in turn according to the maximum value of the evaporation parameter and its fluctuation range, which realizes segmentation of the equal diameter process based on physical parameters rather than fuzzy experience, helps to more accurately identify and locate different equal diameter stages, which is conducive to real-time monitoring and mastering of key nodes of crystal growth by technicians, and timely taking measures to adjust process parameters such as power of the heater, crystal pulling speed, liquid port distance compensation, etc., to maintain the stability of crystal growth and improve the quality of the crystal, and further avoid the adjustment blindness and invalidity caused by unclear segmentation principle in the traditional method.

[0067] For example, the predetermined percentage can be 5%, 10%, or 15%, etc.

[0068] In some other embodiments, according to the first correspondence relationship, the segmentation principle of the single crystal silicon rod in the constant diameter process is determined, including: calculating the evaporation parameter change rate in the first correspondence relationship, determining that the constant diameter length corresponding to the evaporation parameter change rate with an absolute value less than or equal to 5e18 is the constant diameter length range corresponding to the constant diameter middle period; determining that the constant diameter length range corresponding to the constant diameter early period is less than a third length, the third length being the minimum value of the constant diameter length range corresponding to the constant diameter middle period; determining that the constant diameter length range corresponding to the constant diameter late period is greater than a fourth length and less than or equal to the maximum constant diameter length in the first correspondence relationship, the fourth length being the maximum value of the constant diameter length range corresponding to the constant diameter middle period.

[0069] In the embodiments, the constant diameter length corresponding to the constant diameter middle period, the constant diameter early period and the constant diameter late period is determined in sequence according to the change rate of the evaporation parameter, which realizes segmentation of the constant diameter process based on physical parameters instead of fuzzy experience, helps to more accurately identify and locate different constant diameter stages, which is beneficial for technicians to monitor and master the key nodes of crystal growth in real time, and timely take measures to adjust the process parameters such as the power of the heater, the crystal pulling speed, the liquid port distance compensation, etc., to maintain the stability of crystal growth and improve the crystal quality, and further avoid the blindness and invalidity of adjustment caused by unclear segmentation principle in the traditional method.

[0070] Further, according to the current constant diameter stage of the single crystal silicon rod, the growth of the single crystal silicon rod is controlled by using the control strategy corresponding to the current constant diameter stage, including: in the case that the current constant diameter stage is the constant diameter early period, at least controlling the heating power of the heater of the crucible to decrease with the increase of the constant diameter length; in the case that the current constant diameter stage is the constant diameter middle period, adjusting the crystal pulling speed of the single crystal silicon rod according to the fluctuation of the pulling speed of the single crystal silicon rod; in the case that the current constant diameter stage is the constant diameter late period, adjusting the heating power according to the heating power fluctuation of the constant diameter middle period relative to the constant diameter early period. Since the thermodynamic equilibrium conditions of the constant diameter early period, the constant diameter middle period and the constant diameter late period are different, different measures need to be taken to maintain the stability of the growth interface, and the embodiments propose differentiated control strategies according to the characteristics of different constant diameter stages, which realizes accurate regulation and control of the crystal growth process, can effectively reduce the breakage rate, and improve the continuity and consistency of crystal growth.

[0071] According to some embodiments of the present application, the crystal rotation speed of the single crystal silicon rod is adjusted according to the fluctuation of the pulling speed of the single crystal silicon rod, including: in the case that the change rate of the pulling speed is greater than a predetermined threshold, the crystal rotation speed is uniformly reduced at a predetermined frequency; in the case that the change rate of the pulling speed is less than or equal to the predetermined threshold, the crystal rotation speed is uniformly increased at the predetermined frequency. Since the problem of imbalance of the heat system mainly exists in the isodiametric middle period due to the oscillation of the crystal pulling speed or power, in the embodiment, the fluctuation of the pulling speed is monitored in real time, and when the fluctuation exceeds the predetermined threshold, the crystal rotation speed compensation is triggered to change the forced convection strength to quickly balance and match the crystal pulling speed and the isodiametric power, which can effectively suppress the influence of the heat system oscillation caused by the mismatch of the two on the crystal growth, and further reduce the breakage rate of the single crystal silicon rod in the initial isodiametric period.

[0072] Exemplarily, the predetermined threshold can be ±8%. The predetermined frequency can be 45 min / time. The crystal rotation speed value adjusted in each period can be 1.

[0073] In another embodiment of the present application, the heating power is adjusted according to the fluctuation of the heating power in the isodiametric middle period relative to the isodiametric initial period, including: in the case that the change rate of the heating power in the isodiametric middle period relative to the isodiametric initial period satisfies (0, 2%], the heater is controlled to work at a set power; in the case that the change rate of the heating power satisfies (2%, 5%], the heater is controlled to work at a first multiple of the set power, and the first multiple is greater than 1; in the case that the change rate of the heating power is greater than 5%, the heater is controlled to work at a second multiple of the set power, and the second multiple is greater than the first multiple. Since the problem of insufficient or excessive power compensation mainly exists in the isodiametric later period, in the embodiment, the heater power is compensated according to the change of the heating power in the isodiametric middle period relative to the isodiametric initial period, which not only superimposes the cumulative error of the isodiametric initial period and the isodiametric middle period in the isodiametric later period, so that the control accuracy of the whole isodiametric growth process is high, but also further ensures the thermal stability of the crystal in the isodiametric later period, and further reduces the breakage problem caused by insufficient or excessive compensation of the heat source in the isodiametric later period.

[0074] In some embodiments, the first multiple is greater than 1 and less than 1.5. The change rate of the heating power is greater than 5% and less than 20%.

[0075] Exemplarily, the first multiple can be 1.1, and the second multiple can be 1.2.

[0076] In some other optional embodiments, at least the heating power of the crucible's heater is controlled to decrease as the equal-diameter length increases, including: controlling the liquid mouth distance of the single crystal silicon rod to remain unchanged, and controlling the heating power of the crucible's heater to decrease as the equal-diameter length increases. The liquid mouth distance refers to the distance from the melt surface to the seed crystal or seed crystal. In the early stage of equal diameter, there are problems such as the melt temperature being too high and the growth interface stress being too large. This technical solution balances the equal-diameter power and the liquid mouth distance compensation rate to maintain the liquid mouth distance unchanged. The constant liquid mouth distance helps to maintain the temperature gradient of the growth interface. On this basis, it ensures that the power is reduced in time when the pulling speed slowly increases, avoids the problem of single crystal silicon rod breakage caused by excessive heat input, and improves the continuity of crystal growth.

[0077] The comparison of the breakage rate of the obtained single crystal silicon rods at each equal diameter stage is shown in the figure below: Figure 2 As shown, Figure 2 In the figure, the vertical axis represents the disconnection rate, which is given by Figure 2 As can be seen, this solution significantly improves wire breakage at each stage of equal diameter compared to non-implementation. Calculations show that this solution reduces the wire breakage rate by 43.1% compared to the manual segmentation solution, and reduces the time required to resolve wire breakages to less than two weeks.

[0078] Another aspect of an embodiment of the present application further provides a silicon wafer, which is obtained by cutting a single crystal silicon rod using a cutting process, and the single crystal silicon rod is prepared using any of the single crystal silicon rod preparation methods described above, and the single crystal silicon rod has a wire breakage rate of less than or equal to 0.2 during the equal diameter process.

[0079] In the embodiment, the single crystal silicon rods cut to form silicon wafers are prepared using the preparation method. Through this method, the breakage rate of the single crystal silicon rods during the equal-diameter growth process can be controlled below 0.2, thereby reducing the overall production cost of the silicon wafers and improving the material utilization and production efficiency of the silicon wafers.

[0080] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the implementation process of the method for preparing a single crystal silicon rod of the present application will be described in detail below with reference to specific embodiments.

[0081] This embodiment provides a method for preparing a single crystal silicon rod, which specifically includes the following steps:

[0082] A 263 mm single crystal silicon rod is pulled according to the scheme that the polycrystal is pure feeding, the feeding amount is 920 Kg, the hot zone size is 36 inches, the crystal diameter is 263 mm, the argon flow rate is 901 pm, the furnace pressure is 7 Torr, the crucible rotation speed is 4-7 rpm, the crystal rotation speed is 8 rpm, and the single element feeding amount of antimony dopant is 4.5 g, and then the resistivity of the single crystal silicon rod is measured every 50 mm, and the curve of the constant diameter length and the resistivity of the single crystal silicon rod is established as shown in Figure 3 , Figure 3 In the figure, the abscissa represents the constant diameter length, in mm, and the ordinate represents the resistivity, in Ω·cm, Figure 3 The first curve and the second curve are shown, the first curve represents the corresponding relationship between the first resistivity (i.e. the resistivity corresponding to the segregation) and the constant diameter length (i.e. the second corresponding relationship), and the second curve represents the corresponding relationship between the second resistivity (i.e. the resistivity corresponding to the segregation and evaporation) and the constant diameter length (i.e. the third corresponding relationship);

[0083] According to the first curve and the second curve in Figure 3 , the evaporation constant and the evaporation amount of antimony at different constant diameter lengths along the axial direction of the crystal are simulated and calculated, so that the fitting degree of the first curve and the second curve is ≥ 99.8%, a corresponding relationship graph representing the constant diameter length and the resistivity corresponding to the evaporation of the single crystal silicon rod is obtained as shown in Figure 4 , and a corresponding relationship graph representing the constant diameter length and the evaporation constant of the single crystal silicon rod is obtained as shown in Figure 5 , and / or a corresponding relationship graph representing the constant diameter length and the evaporation amount of the single crystal silicon rod is obtained as shown in Figure 6 Thus, the first corresponding relationship is obtained, wherein, Figure 4 In the figure, the abscissa represents the constant diameter length, in mm, and the ordinate represents the resistivity, in Ω·cm, Figure 5 In the figure, the abscissa represents the constant diameter length, in cm, and the ordinate represents the evaporation constant, in cm / s, Figure 6 In the figure, the abscissa represents the constant diameter length, in cm, and the ordinate represents the evaporation amount, in atoms;

[0084] According to the first corresponding relationship, the segmentation principle of the single crystal silicon rod during the constant diameter process is as follows:

[0085] Early constant diameter: constant diameter length 0-1500 mm;

[0086] Middle constant diameter: constant diameter length 1500-2500 mm (excluding the left end point);

[0087] Late constant diameter: constant diameter length > 2500 mm;

[0088] The isodiametric growth process of 36-inch hot field down-drawing 263mm crystal can be completed by the embodiment, and the operation needs to be repeated for segmentation of other different thermal fields and different products.

[0089] Finally, the parameters are adaptively controlled according to the isodiametric stage of the single crystal silicon rod:

[0090] In the early isodiametric stage, the latent heat of crystallization rises, and the heater power needs to be reduced to maintain thermal balance (ΔE heater + ΔE latent heat of crystallization > ΔE dissipation). The common phenomenon is that the melt temperature is too high, which is caused by excessive stress of the growth interface. Therefore, the isodiametric power and the liquid port distance compensation rate need to be balanced; the crystal pulling rate is slowly increased, and the power is timely reduced;

[0091] In the middle isodiametric stage, the thermal system reaches balance (ΔE heater = ΔE latent heat of crystallization, and the total heat input = dissipation). The common phenomenon is that the pulling rate oscillates or the power oscillates after the break, and the main reason is that the thermal system oscillates due to the failure of the isodiametric power and the isodiametric pulling rate to match in time;

[0092] In the late isodiametric stage, the heater power needs to be increased (ΔE heater + ΔE latent heat of crystallization < ΔE dissipation) due to the increase of the dissipation caused by the increase of the crystal surface area. The common phenomenon is that the heater power compensation is insufficient or excessive, which causes the thermal system to collapse. The main reason is that the cumulative control error in the early and middle isodiametric stages and the unreasonable temperature compensation setting cause the problem.

[0093] Further, for the early isodiametric stage, the core problem is that the melt temperature is too high and the growth interface stress is too large. The improvement measure can be to balance the isodiametric power and the liquid port distance compensation rate, to ensure that the power is timely reduced when the pulling rate slowly increases, and to avoid excessive heat input. For example, in the conventional isodiametric parameters, the power change column is 0 before the crystal length is less than or equal to 1500mm, and the optimized isodiametric parameters are shown in Table 1. In Table 1, the negative value of the power represents the decrease of the power.

[0094] Table 1

[0095]

[0096]

[0097] For the middle isodiametric stage, the core problem is that the pulling rate or power oscillation causes the thermal system to be out of balance. The improvement measure can be to monitor the matching of the pulling rate and the power in real time, and to set a dynamic compensation algorithm. For example, when the pulling rate fluctuation exceeds ±8% of the set value, the system automatically triggers the compensation of the crystal rotation speed (i.e., the crystal rotation speed-1 is triggered when the pulling rate fluctuation exceeds +8% of the set value, and the crystal rotation speed+1 is triggered when the pulling rate fluctuation exceeds -8% of the set value), and the compensation frequency is 45min / time. The forced convection strength is changed to quickly balance the pulling rate and the power;

[0098] For the constant diameter late stage, the core problem is insufficient or excessive power compensation, superimposed with the cumulative error of the initial / intermediate stage, and the improvement measures can be monitoring the constant diameter power a of 0 mm and the constant diameter power b of 1500 mm, when 0% < (a-b) / a < 2%, the power change value of the crystal length ≥ 2500 mm is compensated by the current value * 1.0 times coefficient; when 2% < (a-b) / a < 5%, the power change value of the crystal length ≥ 2500 mm is compensated by the current value * 1.1 times coefficient; when (a-b) / a > 5%, the power change value of the crystal length ≥ 2500 mm is compensated by the current value * 1.2 times coefficient.

[0099] The application associates the disconnection phenomenon with the dynamic change of the thermal system, avoids the one-sidedness of relying only on the apparent feature classification, and can accurately locate the thermal imbalance stage; through the evaporation parameter interval division, the process adjustment has a clear phased goal, for example, the initial stage focuses on balancing the power and the liquid port distance, and the late stage focuses on the cumulative error of power compensation, which can improve the process debugging efficiency; for different thermal fields / products, only the process of "pulling crystal-measuring resistivity-fitting evaporation parameters" needs to be repeated to establish the corresponding interval, which breaks through the equipment limitation of experience classification and has strong reproducibility. The application realizes the following functions:

[0100] Strong correlation between the evaporation amount of antimony and temperature: antimony evaporates on the free surface of the melt, and its evaporation rate is exponentially related to the melt temperature (the evaporation constant increases with the increase of temperature). When the thermal system is unbalanced, temperature fluctuation directly leads to the change of evaporation amount, and through the difference between the measured resistivity curve (containing evaporation effect) and the simulation curve, the real-time state of the melt temperature can be deduced;

[0101] Scientific rationality: through the numerical division of evaporation constant and evaporation amount, the subjectivity of human experience is avoided, and the process adjustment has a quantitative basis, which can improve the control accuracy in the production process;

[0102] Mapping of parameters and process adjustment: for example, if the measured resistivity of a certain length is lower than the simulation value, it indicates that the antimony evaporation amount is small, the melt temperature is low, and the heater power needs to be increased; otherwise, the power needs to be reduced;

[0103] Logical closed loop: "thermal balance state → antimony evaporation behavior → resistivity difference → interval division → process adjustment" forms a complete causal chain, which is more rigorous in logic and more efficient than the existing technology "apparent feature → trial and error adjustment".

[0104] The technical features of the above-described embodiments can be combined in any way. To make the description concise, not all possible combinations of the technical features in the embodiments are described, but as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present disclosure.

[0105] From the above description, it can be seen that the embodiments described in the application achieve the following technical effects:

[0106] 1) In the preparation method of the single crystal silicon rod, first, a first corresponding relationship between the constant diameter length of the single crystal silicon rod and the evaporation parameters of the dopant is established; then, according to the first corresponding relationship, a segmentation principle including the constant diameter stage and the corresponding constant diameter length range is determined; then, according to the segmentation principle and the actual constant diameter length of the single crystal silicon rod, the constant diameter stage currently occupied by the single crystal silicon rod is determined; finally, a control strategy suitable for the constant diameter stage currently occupied is used to control the growth of the single crystal silicon rod in the current constant diameter stage. According to the corresponding relationship between the constant diameter length and the evaporation parameters of the dopant, the constant diameter stage is divided. Since the evaporation parameters of the dopant are directly related to the thermal equilibrium state, the segmentation principle of the constant diameter stage is more scientific and reasonable, avoiding the subjectivity of artificially experienced division of the constant diameter stage. The corresponding control strategy is executed in each constant diameter stage to control the growth of the single crystal silicon rod, ensuring that the growth of the single crystal silicon rod in each constant diameter stage is more stable and controllable, thereby reducing the breakage rate of the single crystal silicon rod during the constant diameter process, reducing the production cost of the single crystal silicon rod and improving the material utilization rate during the growth process of the single crystal silicon rod.

[0107] 2) The silicon wafer is obtained by cutting the single crystal silicon rod, and the single crystal silicon rod is prepared by the preparation method. Through the method, the breakage rate of the single crystal silicon rod during the constant diameter growth process can be controlled to be less than 0.2, thereby reducing the overall production cost of the silicon wafer, improving the material utilization rate and production efficiency of the silicon wafer.

[0108] Those skilled in the art can understand that the embodiments described are specific embodiments of the application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the application, therefore the protection scope of the application should be limited by the scope defined in the claims.

Claims

1. A method for preparing a single crystal silicon rod, characterized in that: include: Establishing a first corresponding relationship, wherein the first corresponding relationship is a corresponding relationship between the equal diameter length of the single crystal silicon rod and the evaporation parameter of the dopant in the crucible during the historical preparation process; Determining, based on the first corresponding relationship, a segmentation principle for the single crystal silicon rod in a diameter equalization process, the segmentation principle including a plurality of diameter equalization stages and a diameter equalization length range corresponding to each of the diameter equalization stages, the plurality of diameter equalization stages including an early diameter equalization stage, a middle diameter equalization stage, and a late diameter equalization stage; Determining a current equal-diameter stage of the single crystal silicon rod according to the segmentation principle and an actual equal-diameter length of the single crystal silicon rod during the current preparation process; According to the current equal-diameter stage of the single crystal silicon rod, the growth of the single crystal silicon rod is controlled by adopting a control strategy corresponding to the current equal-diameter stage.

2. The method for preparing a single crystal silicon rod according to claim 1, wherein: Establishing the first correspondence includes: Obtaining a second corresponding relationship and a third corresponding relationship, wherein the second corresponding relationship is a simulated corresponding relationship between the first resistivity of the single crystal silicon rod and the equal diameter length, and the third corresponding relationship is a corresponding relationship between the second resistivity of the single crystal silicon rod and the equal diameter length during the historical preparation process, wherein the first resistivity is the resistivity of the single crystal silicon rod when only the segregation behavior of the dopant is considered, and the second resistivity is the resistivity of the single crystal silicon rod measured when both the segregation behavior and the evaporation behavior of the dopant are considered; The first corresponding relationship is determined according to the second corresponding relationship and the third corresponding relationship.

3. The method for preparing a single crystal silicon rod according to claim 2, wherein: Determining the first corresponding relationship according to the second corresponding relationship and the third corresponding relationship includes: Calculating, based on the second corresponding relationship and the third corresponding relationship, how the difference between the second resistivity and the first resistivity changes with the constant diameter length; The difference between the second resistivity and the first resistivity is converted into the evaporation amount and / or evaporation constant of the dopant to obtain the first corresponding relationship characterizing the change of the evaporation amount and / or evaporation constant with the equal diameter length.

4. The method for preparing a single crystal silicon rod according to claim 1, wherein: Determining, based on the first corresponding relationship, a segmentation principle of the single crystal silicon rod in a process of equalizing diameters includes: Determining, based on the maximum value of the evaporation parameter in the first corresponding relationship, a range of the equal-diameter length corresponding to the mid-equal-diameter period as [first length, second length], where the first length is the equal-diameter length corresponding to a difference between the maximum value and a predetermined percentage of the maximum value in the first corresponding relationship, and the second length is the equal-diameter length corresponding to a sum of the maximum value and a predetermined percentage of the maximum value in the first corresponding relationship, where the predetermined percentage ranges from 5% to 15%; According to the first length, determining that the constant diameter length range corresponding to the initial constant diameter stage is smaller than the first length; According to the second length and the maximum equal-diameter length in the first corresponding relationship, the equal-diameter length range corresponding to the later equal-diameter period is determined to be (second length, maximum equal-diameter length).

5. The method for preparing a single crystal silicon rod according to claim 1, wherein: Determining, based on the first corresponding relationship, a segmentation principle of the single crystal silicon rod in a process of equalizing diameters includes: Calculating the evaporation parameter change rate in the first corresponding relationship, and determining that the constant diameter length corresponding to the evaporation parameter change rate having an absolute value less than or equal to 5e18 is the constant diameter length range corresponding to the middle constant diameter period; Determining that the equal-diameter length range corresponding to the initial equal-diameter stage is smaller than a third length, and the third length is a minimum value of the equal-diameter length range corresponding to the mid-stage equal-diameter stage; Determine that the equal-diameter length range corresponding to the late equal-diameter stage is greater than the fourth length and less than or equal to the maximum equal-diameter length in the first corresponding relationship, and the fourth length is the maximum value of the equal-diameter length range corresponding to the middle equal-diameter stage.

6. The method for preparing a single crystal silicon rod according to claim 1, wherein: According to the current equal diameter stage of the single crystal silicon rod, the growth of the single crystal silicon rod is controlled by adopting a control strategy corresponding to the current equal diameter stage, including: When the current equal-diameter stage is the initial equal-diameter stage, at least controlling the heating power of the crucible heater to decrease as the equal-diameter length increases; When the current equal-diameter stage is the middle equal-diameter stage, adjusting the rotation speed of the single crystal silicon rod according to fluctuations in the pulling speed of the single crystal silicon rod; When the current equal-diameter stage is the late equal-diameter stage, the heating power is adjusted according to the fluctuation of the heating power in the middle equal-diameter stage relative to the early equal-diameter stage.

7. The method for preparing a single crystal silicon rod according to claim 6, wherein: Adjusting the crystal rotation speed of the single crystal silicon rod according to the fluctuation of the pulling speed of the single crystal silicon rod includes: When the rate of change of the pulling speed is greater than a predetermined threshold, uniformly reducing the crystal rotation speed according to a predetermined frequency; When the rate of change of the pulling speed is less than or equal to the predetermined threshold, the crystal rotation speed is uniformly increased according to the predetermined frequency.

8. The method for preparing a single crystal silicon rod according to claim 6, wherein: Adjusting the heating power according to the fluctuation of the heating power in the middle stage of equal diameter relative to the early stage of equal diameter includes: When the heating power change rate of the middle stage of the equal diameter relative to the initial stage of the equal diameter satisfies (0, 2%), the heater is controlled to operate at a set power; When the heating power change rate satisfies (2%, 5%), controlling the heater to operate at a first multiple of the set power, the first multiple being greater than 1; When the heating power change rate is greater than 5%, the heater is controlled to operate at a second multiple of the set power, where the second multiple is greater than the first multiple.

9. The method for preparing a single crystal silicon rod according to claim 6, wherein: At least controlling the heating power of the heater of the crucible to decrease as the constant diameter length increases, comprising: The liquid mouth distance of the single crystal silicon rod is controlled to remain unchanged, and the heating power of the heater of the crucible is controlled to decrease as the equal diameter length increases.

10. A silicon wafer, characterized in that: The silicon wafer is obtained by cutting a single crystal silicon rod using a cutting process, and the single crystal silicon rod is prepared using the method for preparing a single crystal silicon rod according to any one of claims 1 to 9, and the wire breakage rate of the single crystal silicon rod in the equal diameter process is less than or equal to 0.2.

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