Determining whether the crystal seeding temperature of a single crystal furnace is stable and a method for preparing single crystal silicon by Czochralski method

Abstract

The present application discloses a method for determining the seeding temperature of a single crystal furnace and a method for preparing single crystal silicon by a Czochralski method. The method comprises: measuring the temperature of the melt used for seeding in the single crystal furnace before seeding, and obtaining a temperature-time curve; performing Fourier analysis on the temperature-time curve to obtain a frequency-amplitude curve; after judging that the melt temperature has not changed dramatically according to the temperature-time curve, using the frequency-amplitude curve with a stable seeding temperature as a standard reference curve, and comparing the obtained frequency-amplitude curve with the standard reference curve to judge whether the seeding temperature is stable. The method described in the present application improves the accuracy of judging the stability of the seeding temperature and reduces the wire breakage rate caused by misjudgment of the seeding temperature through Fourier analysis assistance and time-temperature curve.

Description

Technical Field

[0001] The present application relates to the field of single crystal silicon preparation, and in particular to a method for determining whether the crystal seeding temperature of a single crystal furnace is stable and preparing single crystal silicon by a Czochralski method. Background Art

[0002] The industry usually uses the Czochralski method to prepare large-sized semiconductor-grade single crystal silicon. The Czochralski method for preparing single crystal silicon has the following processes: chemical reaction, temperature stabilization, seeding, shouldering, equal diameter, finishing, cooling, and rod removal. Among them, the solution temperature needs to be stabilized at the seeding temperature before seeding. Generally, the seed crystal is immersed in the silicon melt, and the brightness and shape of the aperture at the contact point between the seed crystal and the melt are observed to observe whether the seeding temperature is appropriate. When the seeding temperature is not appropriate, the temperature needs to be adjusted manually.

[0003] However, when using the Czochralski method to prepare large-sized semiconductor-grade single crystal silicon, a magnetic field is usually used to control melt convection to control crystal defects, oxygen content and impurity distribution. The added magnetic field inhibits melt convection, and the hot melt at the crucible wall is difficult to quickly reach the liquid surface. Manually adjusting the temperature to the liquid surface temperature will have a lag of up to several hours, resulting in a lot of time spent in the process of finding the seeding temperature, affecting production capacity.

[0004] Due to the periodicity of melt flow and the temperature fluctuation caused by turbulence, the temperature at the location of the seed crystal is not a constant, but fluctuates within a certain range, and the measurement accuracy of the infrared thermometer used in industry is limited. Therefore, it is difficult to determine whether the melt temperature is stable by conventionally looking at the temperature curve. Usually, the time average method is used to deal with temperature fluctuations to obtain a gentle curve, but the method will lose the periodic characteristics of fluid flow.

[0005] Therefore, improvements are needed to solve the above problems. Summary of the invention

[0006] In view of the problems existing in the prior art, the present application provides a method for determining the seeding temperature of a single crystal furnace, the method comprising:

[0007] Before seeding, the temperature of the melt used for seeding in the single crystal furnace is measured to obtain a temperature-time curve;

[0008] Performing Fourier analysis on the temperature-time curve to obtain a frequency-amplitude curve;

[0009] After judging that the melt temperature has no drastic change according to the temperature-time curve, the frequency-amplitude curve of the stable seeding temperature is used as the standard reference curve, and the obtained frequency-amplitude curve is compared with the standard reference curve to judge whether the seeding temperature is stable.

[0010] Optionally, determining whether the seeding temperature is stable includes:

[0011] The position and amplitude value of the amplitude peak appearing in the obtained frequency-amplitude curve are compared with the position and amplitude value of the corresponding amplitude peak in the standard reference curve. If the position and amplitude value of the amplitude peak in the frequency-amplitude curve and the standard reference curve correspond to each other, the seeding temperature is stable.

[0012] Optionally, the method comprises:

[0013] First, determine whether the position where the amplitude peak appears in the frequency-amplitude curve corresponds to the position of the corresponding amplitude peak in the standard reference curve;

[0014] If the amplitude peaks in the frequency-amplitude curve and the standard reference curve correspond to each other, it is further determined whether the difference between the amplitude values ​​of the specific amplitude peaks in the frequency-amplitude curve and the standard reference curve is within a preset threshold. If it is within the preset threshold, the seeding temperature is stable; if it exceeds the preset threshold, the seeding temperature is unstable.

[0015] Optionally, determining whether the amplitude peaks in the frequency-amplitude curve and the standard reference curve correspond to each other includes:

[0016] If the difference between the position of the amplitude peak in the frequency-amplitude curve and the position of the amplitude peak in the standard reference curve is within a set threshold, it is determined that the amplitude peaks in the frequency-amplitude curve and the standard reference curve correspond to each other;

[0017] If the difference between the position of the amplitude peak in the frequency-amplitude curve and the position of the amplitude peak in the standard reference curve exceeds a set threshold, it is determined that the amplitude peaks in the frequency-amplitude curve and the standard reference curve do not correspond to each other.

[0018] Optionally, the temperature of the melt used for seeding in the single crystal furnace is measured at predetermined time intervals, and a temperature-time curve is obtained.

[0019] Optionally, the temperature of the melt is the temperature at a measurement time point or the average temperature within a set time period.

[0020] Optionally, Fourier analysis is performed on the obtained temperature-time curve at preset time intervals to obtain a frequency-amplitude curve.

[0021] Optionally, Fourier analysis is performed on the temperature-time curve obtained at any previous time point at preset time intervals to obtain a frequency-amplitude curve.

[0022] Optionally, the no drastic change in the melt temperature means that the change difference of the melt temperature is within an error threshold range.

[0023] The present application also provides a method for preparing single crystal silicon by the Czochralski method, the method comprising determining the seeding temperature based on the method for determining the seeding temperature of the single crystal furnace as described above.

[0024] In order to solve the existing technical problems, the present application provides a method for determining the seeding temperature of a single crystal furnace and a method for preparing single crystal silicon by a Czochralski method, in which Fourier analysis is introduced to analyze the period of temperature fluctuations to assist in judging the stability of the solution temperature. Before seeding, the parameters in the single crystal furnace are usually unchanged to maintain the stability of the melt temperature, and the solution temperature fluctuations are caused by fluid instability. The instability shows a certain periodicity when the parameters in the single crystal furnace remain unchanged, so the temperature fluctuations will also show a certain periodicity. Therefore, the period of melt temperature fluctuations in each stage can be observed using Fourier analysis, thereby judging the stability of the seeding temperature. The method described in the present application improves the accuracy of judging the stability of the seeding temperature through the assistance of Fourier analysis and time-temperature curves, and reduces the disconnection rate caused by misjudgment of the seeding temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other purposes, features and advantages of the present invention will become more apparent by describing the embodiments of the present invention in more detail in conjunction with the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings, the same reference numerals generally represent the same components or steps. In the accompanying drawings,

[0026] Figure 1 A schematic flow chart of a method for determining the seeding temperature of a single crystal furnace described in an embodiment of the present application;

[0027] Figure 2 A schematic diagram of a temperature-time curve described in an embodiment of the present application;

[0028] Figure 3 A schematic diagram of a frequency-amplitude curve in an embodiment of the present application;

[0029] Figure 4 FIG. 1 is a schematic diagram of a frequency-amplitude curve used as a standard reference curve in an embodiment of the present application. DETAILED DESCRIPTION

[0030] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present application. However, it is apparent to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features well known in the art are not described.

[0031] It should be understood that the present application can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present application to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0032] It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as a second element, component, region, layer or part.

[0033] Spatially relative terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used herein for convenience of description to describe the relationship of one element or feature to other elements or features shown in the figures. It should be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation shown in the figures.

[0034] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0035] Embodiments of the invention are described herein with reference to cross-sectional views as schematic diagrams of ideal embodiments (and intermediate structures) of the present application. Thus, variations from the shapes shown due to, for example, manufacturing techniques and / or tolerances can be expected. Therefore, embodiments of the present application should not be limited to the specific shapes of the zones shown herein, but include shape deviations due to, for example, manufacturing. Therefore, the zones shown in the figures are schematic in nature, and their shapes are not intended to display the actual shapes of the zones of the device and are not intended to limit the scope of the present application.

[0036] In order to solve the existing problems, the solution adopted is that the temperature is equal to the freezing point when the solid-liquid coexistence state is achieved. In the process of material transformation, when the temperature is detected to be unchanged for more than 5 minutes, the temperature is set to the seeding temperature. In the later stage of material transformation, the temperature is stabilized at the seeding temperature for more than 20 minutes using automatic power control, and then seeding is started. However, the method does not explain how to determine whether the seeding temperature is stable in the case of drastic temperature fluctuations after adding a magnetic field to suppress fluid convection.

[0037] When preparing large-sized semiconductor-grade single crystal silicon by the Czochralski method, a magnetic field is usually used to control melt convection to control crystal defects, oxygen content and impurity distribution. The added magnetic field inhibits melt convection, and the hot melt at the crucible wall is difficult to quickly reach the liquid surface. Manually adjusting the temperature to the liquid surface temperature will have a lag of up to several hours, resulting in a lot of time spent in the process of finding the seeding temperature, affecting production capacity. The introduction of the magnetic field will also increase the degree of melt temperature fluctuation.

[0038] In order to solve the problem of the present application, the present invention provides a method for determining the seeding temperature of a single crystal furnace, such as Figure 1 As shown, the method includes:

[0039] Step S1: before seeding, measuring the temperature of the melt used for seeding in the single crystal furnace, and obtaining a temperature-time curve;

[0040] Step S2: performing Fourier analysis on the temperature-time curve to obtain a frequency-amplitude curve;

[0041] Step S3: after judging that the melt temperature has no drastic change according to the temperature-time curve, the frequency-amplitude curve of the stable seeding temperature is used as the standard reference curve, and the obtained frequency-amplitude curve is compared with the standard reference curve to judge whether the seeding temperature is stable.

[0042] Fourier analysis is introduced in the method to analyze the cycle of temperature fluctuations, and the stability of solution temperature is assisted in judging. Before seeding, usually the parameters in the single crystal furnace are unchanged to maintain the stability of the melt temperature, and the solution temperature fluctuation is caused by fluid instability. The instability shows a certain periodicity when the parameters in the single crystal furnace are unchanged, and thus the temperature fluctuation will also show a certain periodicity. Therefore, the cycle of melt temperature fluctuations in each stage can be observed using Fourier analysis, so as to judge the stability of seeding temperature. The method described in the present application improves the accuracy of seeding temperature stability judgment by Fourier analysis assistance and time-temperature curve, and reduces the disconnection rate caused by misjudging the seeding temperature.

[0043] The headset of the present application is described in detail below in conjunction with the accompanying drawings, wherein: Figure 1 A schematic flow chart of a method for determining the seeding temperature of a single crystal furnace described in an embodiment of the present application; Figure 2 A schematic diagram of a temperature-time curve described in an embodiment of the present application; Figure 3 A schematic diagram of a frequency-amplitude curve in an embodiment of the present application; Figure 4 FIG. 1 is a schematic diagram of a frequency-amplitude curve used as a standard reference curve in an embodiment of the present application.

[0044] The method for determining the seeding temperature of a single crystal furnace described in the present application is applied to preparing single crystals in a single crystal furnace by the Czochralski method, but it should be noted that the method is also applied to other Czochralski methods.

[0045] In step S1, raw silicon material is heated in a single crystal furnace to form a melt. Specifically, the single crystal furnace has a main furnace chamber and a control system, a heating device for heating the silicon material in the crucible is provided in the main furnace chamber, and a temperature measuring device is installed outside the main furnace chamber, and the temperature measuring device can be an infrared thermometer.

[0046] When measuring the temperature of the melt in this step, the temperature of the melt can be measured continuously in real time to obtain a temperature-time curve;

[0047] In addition, the temperature of the melt used for seeding in the single crystal furnace is measured at predetermined time intervals, and the predetermined time is a fixed time period. For example, in one embodiment, the temperature is measured once every 10 seconds.

[0048] After measuring the temperature of the melt, the temperature measurement result can be output in real time, for example, the temperature is measured once every 10 seconds, and the temperature of each temperature measurement time point is output in real time, and a temperature-time curve is established according to the time and temperature.

[0049] In addition, the average temperature within a set time period can also be output. For example, in one embodiment, the temperature is measured every 10 seconds, but the temperature of each temperature measurement time point is not output in real time. Instead, the average value of the 12 temperatures collected within 2 minutes is calculated and the calculated average temperature is output. A temperature-time curve is established based on the time and average temperature.

[0050] In one embodiment, if Figure 2 The temperature-time diagram shown is the temperature 2 hours before seeding started. The data used is the average temperature over 2 minutes.

[0051] from Figure 2 From the temperature-time curve shown, there is an obvious drop in temperature in the first hour, so the temperature is not stable in the first hour. There is a slight fluctuation in the second hour, but it is still difficult to determine whether the temperature has stabilized.

[0052] To this end, step S2 is executed to perform Fourier analysis on the obtained temperature-time curve to obtain a frequency-amplitude curve.

[0053] In this step, the obtained temperature-time curve is subjected to Fourier analysis at preset time intervals to obtain a frequency-amplitude curve. For example, the obtained temperature-time curve is subjected to Fourier analysis every 10 seconds.

[0054] Optionally, the temperature-time curve obtained at any time point before is subjected to Fourier analysis at a preset time interval to obtain a frequency-amplitude curve. In one embodiment of the present application, the melt temperature change in the previous hour is subjected to Fourier analysis at regular intervals to obtain an image of the frequency-amplitude curve. By observing the peak position according to the frequency-amplitude curve, the period of temperature fluctuation can be clearly known.

[0055] In step S3, firstly, it is determined based on the temperature-time curve whether the melt temperature has no drastic change. When it is determined that the melt temperature has no drastic change, the frequency-amplitude curve can be further combined to determine whether the melt temperature is stable.

[0056] The method for determining whether the melt temperature has a drastic change is to pre-set an acceptable temperature error threshold range, and if the change difference of the melt temperature is within the error threshold range, it is determined that the melt temperature has no drastic change.

[0057] Specifically, the crystal seeding temperature fluctuation period of a single crystal furnace is used as a reference, and when the same periodicity appears and the time-averaged temperature is stable, the crystal seeding can be started. In one embodiment, the frequency-amplitude curve of the stable crystal seeding temperature is used as the standard reference curve, and the obtained frequency-amplitude curve is compared with the standard reference curve to obtain a comparison result.

[0058] In the present application, the frequency-amplitude curve of the stable seeding temperature is detected and recorded as a reference for the seeding temperature fluctuation period, and the seeding temperature fluctuation period obtained in real time is compared with the reference to determine whether the temperature is stable.

[0059] The step of comparing the obtained frequency-amplitude curve with the standard reference curve includes:

[0060] The position and amplitude value of the amplitude peak appearing in the obtained frequency-amplitude curve are compared with the position and amplitude value of the corresponding amplitude peak in the standard reference curve. If the position and amplitude value of the amplitude peak in the frequency-amplitude curve and the standard reference curve correspond to each other, the seeding temperature is stable; if they do not correspond, the seeding temperature is unstable.

[0061] In another embodiment, comparing the obtained frequency-amplitude curve with a standard reference curve comprises:

[0062] First, determine whether the position where the amplitude peak appears in the frequency-amplitude curve corresponds to the position where the amplitude peak appears in the standard reference curve, and then determine whether the magnitudes of the amplitude peaks correspond;

[0063] After the positions of the amplitude peaks in the frequency-amplitude curve and the standard reference curve correspond to each other, it can be determined whether the sizes of all the amplitude values ​​correspond. In order to simplify the steps, in one embodiment, it is not necessary to compare the sizes of all the amplitude values. It is only necessary to determine whether the amplitude value difference of a specific amplitude peak in the amplitude peaks of the frequency-amplitude curve and the standard reference curve is within a preset threshold, wherein the amplitude peak at a position close to 0 is usually selected. When the amplitude value difference of a specific amplitude peak in the amplitude peaks of the frequency-amplitude curve and the standard reference curve is within the preset threshold, the seeding temperature is stable. If it exceeds the preset threshold, the seeding temperature is unstable.

[0064] In the present application, the method and standard for determining whether the amplitude peaks in the frequency-amplitude curve and the standard reference curve correspond to each other are:

[0065] A preset threshold value of the position difference of the amplitude peak is preset, and if the difference between the position of the amplitude peak in the frequency-amplitude curve and the position of the amplitude peak in the standard reference curve is within the preset threshold value, it is determined that the amplitude peaks in the frequency-amplitude curve and the standard reference curve correspond to each other;

[0066] If the difference between the position of the amplitude peak in the frequency-amplitude curve and the position of the amplitude peak in the standard reference curve exceeds a set threshold, it is determined that the amplitude peaks in the frequency-amplitude curve and the standard reference curve do not correspond to each other.

[0067] Combine the following Figure 2 and Figure 3 A specific embodiment of the present application is described in detail.

[0068] In this embodiment, the infrared thermometer can output the temperature at 10 second intervals and the average temperature over 2 minutes. Figure 2 This is the temperature-time curve 2 hours before seeding begins, and the data used is the average temperature over 2 minutes. Figure 3 This is a frequency distribution diagram of different time periods within this period, and the data used is the temperature at intervals of 10 seconds.

[0069] From the temperature-time curve, the temperature drops significantly in the first hour, and the difference exceeds the error threshold, so it is determined that the temperature is not stable in the first hour. There is a slight fluctuation in the second hour, and the difference is within the error threshold, but it is difficult to determine whether the temperature has stabilized.

[0070] From the distribution diagram of the frequency-amplitude curve, the frequencies (peak amplitude) 1-3 represent the periodicity of the melt flow, while the frequency (peak amplitude) 4 is close to 0, and the stronger it is, the more non-periodic the melt flow is.

[0071] At 0-1h, the frequencies (peak amplitudes) 1 and 4 are both strong, and the melt has a certain periodicity, but is unstable.

[0072] At 0.5-1.5h, frequencies (peak amplitudes) 2 and 3 appear, frequency (peak amplitude) 4 decreases, and the periodicity of the melt increases.

[0073] At 1-2h, frequency (peak amplitude) 4 further decreased, and frequencies (peak amplitude) 2 and 3 were more significant.

[0074] Will Figure 3 The obtained frequency-amplitude curve and Figure 4 By comparing with the standard reference curve in the frequency-amplitude curve, it can be found that the positions of the amplitude peaks 1-4 in the frequency-amplitude curve correspond to the amplitude peaks 1'-4' in the standard reference curve, and the difference between the specific amplitude peak 4 in the frequency-amplitude curve and the specific amplitude peak 4' in the standard reference curve is within the preset threshold. At this time, the melt tends to be stable and can be seeded.

[0075] In order to solve the existing technical problems, the present application provides a method for determining the seeding temperature of a single crystal furnace and a method for preparing single crystal silicon by a Czochralski method, in which Fourier analysis is introduced to analyze the period of temperature fluctuations to assist in judging the stability of the solution temperature. Before seeding, the parameters in the single crystal furnace are usually unchanged to maintain the stability of the melt temperature, and the solution temperature fluctuations are caused by fluid instability. The instability shows a certain periodicity when the parameters in the single crystal furnace remain unchanged, so the temperature fluctuations will also show a certain periodicity. Therefore, the period of melt temperature fluctuations in each stage can be observed using Fourier analysis, thereby judging the stability of the seeding temperature. The method described in the present application improves the accuracy of judging the stability of the seeding temperature through the assistance of Fourier analysis and time-temperature curves, and reduces the disconnection rate caused by misjudgment of the seeding temperature.

[0076] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0077] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0078] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed.

[0079] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0080] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with features less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.

[0081] It will be understood by those skilled in the art that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0082] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0083] It should be noted that the above embodiments illustrate rather than limit the present application, and that those skilled in the art may devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets should not be constructed as a limitation to the claims. The present application may be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In a unit claim that lists several devices, several of these devices may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names.

Claims

1. A method for determining whether the seeding temperature of a single crystal furnace is stable, characterized in that: The method comprises: Before seeding, the temperature of the melt used for seeding in the single crystal furnace is measured to obtain a temperature-time curve; Fourier analysis is performed on the temperature-time curve to obtain a frequency-amplitude curve; After judging that the change difference of the melt temperature is within the preset temperature error threshold range according to the temperature-time curve, the frequency-amplitude curve of the stable seeding temperature is used as the standard reference curve, and the position and amplitude value of the amplitude peak appearing in the obtained frequency-amplitude curve are compared with the position and amplitude value of the corresponding amplitude peak in the standard reference curve. If the position and amplitude value of the amplitude peak in the frequency-amplitude curve and the standard reference curve correspond to each other, the seeding temperature is stable.

2. The method according to claim 1, characterized in that The method comprises: First, determine whether the position where the amplitude peak appears in the frequency-amplitude curve corresponds to the position of the corresponding amplitude peak in the standard reference curve; If the amplitude peaks in the frequency-amplitude curve and the standard reference curve correspond to each other, it is further determined whether the difference between the amplitude values ​​of the amplitude peaks at the frequency close to 0 position in the frequency-amplitude curve and the standard reference curve is within a preset threshold. If it is within the preset threshold, the seeding temperature is stable; if it exceeds the preset threshold, the seeding temperature is unstable.

3. The method according to claim 2, characterized in that Determining whether the amplitude peaks in the frequency-amplitude curve and the standard reference curve correspond to each other includes: If the difference between the position of the amplitude peak in the frequency-amplitude curve and the position of the amplitude peak in the standard reference curve is within a set threshold, it is determined that the amplitude peaks in the frequency-amplitude curve and the standard reference curve correspond to each other; If the difference between the position of the amplitude peak in the frequency-amplitude curve and the position of the amplitude peak in the standard reference curve exceeds a set threshold, it is determined that the amplitude peaks in the frequency-amplitude curve and the standard reference curve do not correspond to each other.

4. The method according to claim 1, characterized in that: The temperature of the melt used for seeding in the single crystal furnace is measured at predetermined time intervals, and a temperature-time curve is obtained.

5. The method according to claim 4, characterized in that The temperature of the melt is the temperature at the measurement time point or the average temperature within a set time period.

6. The method according to claim 1, characterized in that The obtained temperature-time curve is subjected to Fourier analysis at preset time intervals to obtain a frequency-amplitude curve.

7. The method according to claim 6, characterized in that The temperature-time curve obtained at any previous time point is subjected to Fourier analysis at preset time intervals to obtain a frequency-amplitude curve.

8. A method for preparing single crystal silicon by Czochralski method, characterized in that: The method comprises determining whether the seeding temperature is stable based on the method for determining the seeding temperature of a single crystal furnace according to any one of claims 1 to 7.

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