Preparation method and device of silicon single crystal rod and silicon wafer

Abstract

The invention relates to a preparation method and device of a silicon single crystal rod and a silicon wafer. The method comprises the steps that the diameter change trend of a crystal bar and the temperature change trend of melt are monitored, and a regulation and control starting time point is recognized; and at least one of the heating power of the melt and the lifting speed of the crystal bar is adjusted when the diameter change trend and / or the temperature change trend meet the preset adjustment condition and the adjustment and control starting time point is met. The diameter and the temperature trend are monitored in real time, the regulation and control points are identified, and the power or the pulling speed is adjusted at the initial stage of deviation of the technological parameters, so that line breakage post-processing is converted into active prevention based on data driving, the technological stability is improved, the line breakage risk is reduced, and the production efficiency and the consistency of the crystal quality are improved.

Description

Technical Field

[0001] This application relates to the field of monocrystalline silicon technology, and in particular to a method, apparatus and wafer for preparing monocrystalline silicon rods. Background Technology

[0002] Monocrystalline silicon, as a semiconductor material, has wide applications in integrated circuits, solar cells, sensors, optoelectronic devices, and other fields. Currently, the main method for growing monocrystalline silicon is the Czochralski process (CZ), whose basic steps include melting raw materials, seed crystal welding, pulling single crystals, finishing, and cutting.

[0003] In traditional technology, after a single crystal silicon wire breaks, the single crystal furnace must immediately stop the pulling process. Operators must interrupt the current production process to handle the wire breakage before restarting production, which reduces equipment utilization and production efficiency.

[0004] Therefore, it is necessary to avoid wire breakage during the preparation of monocrystalline silicon. Summary of the Invention

[0005] Therefore, it is necessary to provide a method, apparatus, and silicon wafer for preparing single-crystal silicon rods that can reduce the probability of wire breakage, in order to address the above-mentioned technical problems.

[0006] In a first aspect, this application provides a method for preparing a single-crystal silicon rod, comprising: in a constant diameter growth stage:

[0007] Monitor the diameter change trend of the crystal rod and the temperature change trend of the melt to identify the control start-up time point;

[0008] When the diameter change trend and / or the temperature change trend meet the preset adjustment conditions, and when the control start time point is met, at least one of the heating power of the melt and the lifting speed of the crystal rod is adjusted.

[0009] In one embodiment, monitoring the diameter change trend of the crystal rod and the temperature change trend of the melt includes:

[0010] Obtain the time-series data of the diameter of the crystal rod and the time-series data of the temperature of the melt;

[0011] The rate of change of the diameter time series data per unit time is calculated to obtain the diameter change trend; the rate of change of the temperature time series data per unit time is calculated to obtain the temperature change trend.

[0012] In one embodiment, the step of adjusting at least one of the heating power of the melt and the lifting speed of the crystal rod when the diameter change trend and / or the temperature change trend meet preset adjustment conditions, and when the control start-up time point is met, includes:

[0013] When the current diameter change rate of the crystal rod exceeds the diameter change rate threshold range, the heating power of the melt and the lifting speed of the crystal rod are adjusted simultaneously.

[0014] When the current temperature change rate of the melt exceeds the temperature fluctuation threshold range, the heating power of the melt is adjusted.

[0015] In one embodiment, the lower limit of the diameter change rate threshold range is a first change rate threshold, and the upper limit is a second change rate threshold; the step of simultaneously adjusting the heating power of the melt and the lifting speed of the crystal rod when the current diameter change rate of the crystal rod exceeds the diameter change rate threshold range includes:

[0016] If the current diameter change rate corresponding to the diameter change trend is less than the first change rate threshold, then reduce the heating power and increase the lifting speed of the crystal rod.

[0017] If the current diameter change rate corresponding to the diameter change trend is greater than the second change rate threshold, then increase the heating power and decrease the crystal rod lifting speed.

[0018] In one embodiment, the lower limit of the temperature fluctuation threshold range is a first fluctuation threshold, and the upper limit is a second fluctuation threshold; adjusting the heating power of the melt when the current temperature change rate of the melt exceeds the temperature fluctuation threshold range includes:

[0019] If the current temperature change rate corresponding to the temperature change trend is less than the first fluctuation threshold, then increase the heating power;

[0020] If the current temperature change rate corresponding to the temperature change trend is greater than the second fluctuation threshold, then the heating power is reduced.

[0021] In one embodiment, identifying the control initiation time point includes:

[0022] Once the constant diameter growth stage begins, the moment when the temperature of the melt is first maintained within the target temperature range for a first preset duration and the diameter of the crystal rod is maintained within the target diameter range for a second preset duration is determined as the control start time.

[0023] In one embodiment, the method further includes: continuously heating the molten material to melt at a first power during the melt stage to obtain the melt;

[0024] The heating power includes main heating power and bottom heating power. The main heating power of the first power is 115kW-125kW, and the bottom heating power of the first power is 95kW-105kW.

[0025] In one embodiment, after the melting stage is completed, the heating power is reduced from a first power to a second power, and the constant diameter growth stage is entered.

[0026] The main heating power of the second power is 75kW-85kW, and the bottom heating power of the second power is 65kW-75kW.

[0027] Secondly, this application also provides an apparatus for preparing a single-crystal silicon rod, comprising:

[0028] The monitoring module is used to monitor the diameter change trend of the crystal rod and the temperature change trend of the melt during the constant diameter growth stage, and to identify the control start-up time point.

[0029] An adjustment module is used to adjust at least one of the heating power of the melt and the lifting speed of the crystal rod when the diameter change trend and / or the temperature change trend meet preset adjustment conditions and the adjustment start time point is met.

[0030] Thirdly, this application also provides a silicon wafer, which is formed by preparing and dividing a single-crystal silicon rod using the method described in the first aspect.

[0031] The aforementioned method, apparatus, and wafer for preparing single-crystal silicon rods monitor the diameter change trend of the rod and the temperature change trend of the melt, identifying and controlling the start-up time point. When the diameter change trend and / or temperature change trend meet preset adjustment conditions, and when the control start-up time point is met, at least one of the heating power of the melt and the lifting speed of the rod is adjusted. By monitoring the diameter and temperature trends in real time and identifying the control point, the power or pulling speed is adjusted at the initial stage of process parameter deviation, thereby transforming post-wire breakage processing into data-driven proactive prevention, improving process stability, reducing the risk of wire breakage, and increasing production efficiency and crystal quality consistency. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the complete process for preparing single-crystal silicon rods;

[0034] Figure 2 This is a schematic flowchart of a method for preparing a single-crystal silicon rod in one embodiment;

[0035] Figure 3This is a schematic flowchart of a method for preparing a single-crystal silicon rod in another embodiment;

[0036] Figure 4 This is a schematic flowchart of a method for preparing a single-crystal silicon rod in another embodiment;

[0037] Figure 5 This is a schematic flowchart of a method for preparing a single-crystal silicon rod in another embodiment;

[0038] Figure 6 This is a schematic flowchart of a method for preparing a single-crystal silicon rod in another embodiment;

[0039] Figure 7 This is a structural block diagram of a device for preparing a single-crystal silicon rod in one embodiment. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0041] It should be understood that although the terms “first,” “second,” etc., may be used herein to describe various elements, this does not indicate any order, quantity, or importance, but is merely used to distinguish different components. These terms are used only to distinguish one element from another. For example, without departing from the scope of this application, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. Words such as “comprising” or “including” mean that the element or object preceding the word covers the element or object listed following the word and its equivalents, without excluding other elements or objects.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0043] Czochralski Single Crystal Silicon (CZ-Si) is a silicon material with a single crystal structure produced by the Czochralski method. CZ-Si can be used as a basic material for integrated circuits, supporting the production of devices such as microprocessors and memory chips; it can also be used in high-efficiency solar panels to improve photoelectric conversion efficiency; or it can be used in optoelectronic devices such as LEDs and lasers, relying on the substrate material properties of single crystal silicon to achieve photoelectric conversion.

[0044] In the Czochralski method, polycrystalline silicon is melted in a quartz crucible. A single-crystal silicon seed, fixed to a seed crystal axis, is then brought into contact with the molten silicon surface. By precisely controlling the temperature, seed crystal rotation, and upward pulling speed, the molten silicon arranges itself according to the atomic structure of the seed crystal, gradually solidifying and growing into a complete cylindrical single-crystal silicon rod at the lower end of the seed crystal. During the growth process, the growing crystal may suddenly break, causing it to fall into the molten silicon or interrupting growth, a phenomenon known as crystal pulling wire breakage. After a crystal pulling wire breakage, the single-crystal furnace must immediately stop the pulling process. Operators must interrupt the current production flow to handle the breakage. Before restarting production, it is necessary to reload, remelt, and pull the crystal, leading to an extended single-furnace production cycle and reduced equipment utilization and production efficiency.

[0045] Therefore, it is necessary to reduce the probability of wire breakage during the preparation of monocrystalline silicon.

[0046] In the embodiments of this application, such as Figure 1 As shown, the method for preparing a single-crystal silicon rod includes several stages performed sequentially, specifically including:

[0047] S1, Melting Stage. High-purity polycrystalline silicon raw material and an appropriate amount of dopant are loaded into a high-purity quartz crucible, which is then placed in the graphite heating furnace within the single-crystal furnace. After starting the graphite heating system, while maintaining an appropriate vacuum and stable pressure within the single-crystal furnace, the temperature is gradually increased to above the melting temperature of silicon, generally reaching or exceeding a certain value to ensure that the polycrystalline silicon and dopant are fully melted.

[0048] For example, in conventional technology, the main heating power range for the melt stage is (95kW, 105kW), the bottom heating power range is (85kW, 95kW) to between; the argon flow rate range is (115pm, 125pm); and the crystal rotation rate range is (7rpm, 8rpm).

[0049] S2, Temperature Adjustment Stage. After melting, sensors monitor the liquid surface temperature and fluctuations at the crucible edge and surface. Based on the monitoring results, the crucible is precisely raised to the appropriate seed crystal position. The temperature adjustment stage is used to accurately control the temperature, providing the necessary conditions for subsequent seed crystal introduction.

[0050] For example, in conventional technology, the crucible rotation rate during the temperature control stage ranges from 4.5 rpm to 5.5 rpm.

[0051] S3, Welding Stage. Once the temperature of the polycrystalline silicon melt has stabilized, the seed crystal is slowly lowered to a specific distance from the surface of the molten silicon, then paused briefly to bring the seed crystal temperature as close as possible to the molten silicon, minimizing the risk of thermal shock. Next, the seed crystal is immersed in the molten silicon, allowing a small amount of the seed crystal tip to dissolve and form a clear solid-liquid interface with the molten silicon, completing the welding of the seed crystal and the molten silicon.

[0052] S4, Seed crystal growth stage. After fusion, the seed crystal begins to guide crystal growth. During the seed crystal growth stage, thermal stress caused by the temperature gradient and surface tension of the melt can cause dislocations in the seed crystal lattice, which can be eliminated by a necking process. For example, by rapidly pulling the seed crystal upwards, the crystal growth rate is accelerated, and the diameter of the newly crystallized single-crystal silicon is smaller than that of the seed crystal, forming a narrow neck whose length is approximately a certain multiple of the current crystal diameter, and the rotation rate also has a corresponding range.

[0053] For example, in traditional technology, the main heating power range during the crystallization stage is (50kW, 60kW), the bottom heating is turned off, and the bottom heating power is 0; the crystal rotation rate range is (7rpm, 8rpm); and the crucible rotation rate range is (4.5rpm, 5.5rpm).

[0054] S5, Shoulder Formation Stage. After the crystal is pulled to the target length, the crystal pulling speed is slowed down and the temperature is finely adjusted to rapidly increase the crystal diameter. The shoulder shape is adjusted by coordinating the diameter and temperature until the crystal diameter reaches the preset target diameter.

[0055] For example, in traditional technology, the main heating power range during the shoulder-setting stage is (40kW, 50kW), the bottom heating is turned off, and the bottom heating power is 0; the crystal rotation rate range is (7rpm, 8rpm); and the crucible rotation rate range is (4.5rpm, 5.5rpm).

[0056] S6, Constant Diameter Growth Stage. Once the shoulder reaches the predetermined crystal diameter, the constant diameter growth stage begins. At this stage, the crystal growth rate accelerates and remains almost constant, ensuring the crystal grows to a fixed diameter. During this stage, strict control of the solid-liquid interface temperature gradient and the pulling rate is necessary to guarantee crystal quality.

[0057] For example, in conventional technology, the main heating power range for the constant diameter growth stage is (40kW, 50kW), the bottom heating is turned off, and the bottom heating power is 0; the crystal rotation rate range is (7rpm, 8rpm); and the crucible rotation rate range is (5rpm, 6rpm).

[0058] S7, Final Stage. As crystal growth nears completion, to avoid a large number of dislocations caused by thermal stress from sudden detachment from the liquid surface, the crystal pulling speed needs to be increased and the crystal diameter gradually reduced to form a cone shape, ultimately allowing the crystal to leave the liquid surface.

[0059] S8, the cutting stage. After the finishing process is completed, the grown single-crystal silicon rod is slowly raised into the auxiliary chamber for cooling, thus completing the entire preparation process of single-crystal silicon from raw material to finished product.

[0060] In one embodiment, such as Figure 2 As shown, in Figure 1The method for preparing a single-crystal silicon rod in the constant-diameter growth stage shown includes:

[0061] S201 monitors the diameter change trend of the crystal rod and the temperature change trend of the melt to identify the control start-up time point.

[0062] The diameter of the crystal rod can change in the direction of either increasing or decreasing; or, the diameter can change within a preset time period. Similarly, the temperature of the melt can change in the direction of either increasing or decreasing; or, the temperature can change within a preset time period.

[0063] In this embodiment, during the constant diameter growth stage of the crystal rod, the diameter of the crystal rod and the temperature of the melt are continuously monitored in real time using a monitoring component. The control start-up time point can be the moment when the duration of entering the constant diameter growth stage reaches a preset first growth duration; or, the control start-up time point can be the moment when the diameter of the crystal rod reaches a preset diameter and the temperature of the melt remains at a preset growth temperature for a preset second growth duration; or, the initial moment when the diameter or liquid temperature begins to fluctuate unexpectedly is determined based on the obtained real-time monitoring values, or the critical moment when the diameter or liquid temperature is about to deviate from the process window is determined based on a prediction model, i.e., the control start-up time point is identified.

[0064] Optionally, the monitoring component may include at least one of a liquid temperature sensor, a weight sensor, and an image acquisition component.

[0065] Optionally, the real-time diameter of the crystal rod can be determined by measuring the weight change of the crystal rod using a weight sensor, as well as by the known crystal density and the change in the pulling position. Thus, the trend of the crystal rod's diameter change can be determined by measuring the real-time diameter at multiple moments.

[0066] Optionally, a liquid temperature sensor can be installed at at least one location on the crucible. The real-time temperature of the melt can be determined based on at least one liquid temperature sensor, thereby determining the temperature change trend of the melt through real-time temperatures at multiple moments. Alternatively, the liquid temperature can be measured by a thermocouple located at a preset position, and the temperature change trend of the melt can be obtained based on the real-time measurement value.

[0067] S202, when the diameter change trend and / or temperature change trend meet the preset adjustment conditions, and when the control start-up time point is met, adjust at least one of the heating power of the melt and the lifting speed of the crystal rod.

[0068] The preset adjustment conditions can be that the diameter continuously increases or decreases within a preset time, or the fluctuation value of the liquid temperature within a preset time is greater than the stable threshold.

[0069] In the embodiments of this application, if the diameter change trend shows that the diameter is continuously decreasing, the lifting speed of the crystal rod is reduced, and / or the heating power is increased, so that more heat is obtained at the solid-liquid interface to suppress diameter shrinkage; if the diameter change trend shows that the diameter is continuously increasing, the lifting speed of the crystal rod is increased, and / or the heating power is reduced, so that the diameter shrinks.

[0070] Optionally, if the diameter trend shows that the diameter is continuously decreasing, the lifting speed of the crystal rod is reduced to allow more heat to be obtained at the solid-liquid interface to suppress diameter shrinkage; if the diameter trend shows that the diameter is continuously increasing, the lifting speed of the crystal rod is increased to cause diameter shrinkage.

[0071] Optionally, if the diameter change trend shows that the diameter is continuously decreasing, the heating power is increased to allow more heat to be obtained at the solid-liquid interface to suppress diameter shrinkage; if the diameter change trend shows that the diameter is continuously increasing, the heating power is decreased to allow the diameter to shrink.

[0072] Optionally, if the diameter trend shows that the diameter is continuously decreasing, the lifting speed of the crystal rod is reduced and the heating power is increased to obtain more heat at the solid-liquid interface to suppress diameter shrinkage; if the diameter trend shows that the diameter is continuously increasing, the lifting speed of the crystal rod is increased and the heating power is reduced to cause diameter shrinkage.

[0073] In this embodiment, if the temperature change trend shows that the liquid temperature is less than the stable threshold range within a preset time, the lifting speed of the crystal rod is reduced, and / or the heating power is increased to obtain more heat at the solid-liquid interface; if the temperature change trend shows that the liquid temperature is greater than the stable threshold range within a preset time, the lifting speed of the crystal rod is increased, and / or the heating power is reduced.

[0074] Optionally, if the temperature change trend shows that the liquid temperature is less than the stable threshold range within a preset time, the lifting speed of the crystal rod is reduced; if the temperature change trend shows that the liquid temperature is greater than the stable threshold range within a preset time, the lifting speed of the crystal rod is increased.

[0075] Optionally, if the temperature change trend shows that the liquid temperature is less than the stable threshold range within a preset time, the heating power is increased; if the temperature change trend shows that the liquid temperature is greater than the stable threshold range within a preset time, the heating power is decreased.

[0076] Optionally, if the temperature trend shows that the liquid temperature is less than the stable threshold range within a preset time, the lifting speed of the crystal rod is reduced and the heating power is increased to obtain more heat at the solid-liquid interface; if the temperature trend shows that the liquid temperature is greater than the stable threshold range within a preset time, the lifting speed of the crystal rod is increased and the heating power is reduced.

[0077] In the aforementioned method for preparing single-crystal silicon rods, during the constant-diameter growth stage, the diameter change trend of the rod and the temperature change trend of the melt are monitored to identify the control start-up time point. When the diameter change trend and / or temperature change trend meet preset adjustment conditions, and when the control start-up time point is met, at least one of the melting power and the rod lifting speed is adjusted. By monitoring the diameter and temperature trends in real time and identifying the control point, the power or pulling speed is adjusted at the initial stage of process parameter deviation, thereby transforming post-wire breakage processing into data-driven proactive prevention, improving process stability, reducing the risk of wire breakage, and increasing production efficiency and crystal quality consistency.

[0078] In one embodiment, one implementation of the above-described S201 is provided, such as... Figure 2 As shown, the aforementioned "monitoring of the diameter variation trend of the crystal rod and the temperature variation trend of the melt" includes:

[0079] S301, acquire the timing data of the crystal rod diameter and the timing data of the melt temperature.

[0080] In this embodiment, raw data is continuously acquired via integrated sensors. For the ingot diameter, the real-time weight of the ingot measured by a weight sensor and the seed crystal lifting height recorded by a seed crystal axis position encoder are acquired at a fixed frequency. Based on this, the crystal density, crystal growth geometry, ingot weight, and seed crystal lifting height are used to calculate the crystal diameter value at each moment, forming diameter time-series data. Furthermore, the temperature of the melt region is acquired by a temperature sensor installed near the heater or at the bottom of the crucible, forming a temperature time-series data synchronized with the diameter data timestamp. For example, the fixed frequency can be, for instance, once per second.

[0081] For example, multiple temperature sensors can be set at different locations in the melt, and the current real-time temperature can be obtained by averaging the temperatures from multiple sensors.

[0082] S302, calculate the rate of change of diameter time series data per unit time to obtain the diameter change trend; calculate the rate of change of temperature time series data per unit time to obtain the temperature change trend.

[0083] In this embodiment, for diameter time-series data, the diameter value at the current moment and the previous unit time interval are taken, the difference between the two diameter values ​​is calculated and divided by the unit time to obtain the diameter change rate at the current moment; or, for diameter time-series data, the diameter value at the current moment and a set diameter standard value are taken, the difference between the two diameter values ​​is calculated and divided by the unit time to obtain the diameter change rate at the current moment. For example, the unit of diameter change rate can be millimeters per minute. If the diameter change rate is positive, it indicates that the diameter is showing a "thickening" trend; if the diameter change rate is negative, it indicates that the diameter is showing a "thinning" trend.

[0084] In this embodiment of the application, the same processing is performed on the temperature time series data to calculate the temperature change rate, such as ℃ / minute, to determine whether the liquid temperature is rising, falling or stable.

[0085] In the above-mentioned embodiments, the original sensor data is converted in real time into diameter and temperature change rates that directly characterize the stability of the process state, providing reliable data support for subsequent decision-making and control, thereby upgrading process monitoring from lagging judgments that rely on experience to data-based preventive control.

[0086] In one embodiment, one implementation of S202 above is provided, such as... Figure 4 As shown, the aforementioned "adjusting at least one of the heating power of the melt and the lifting speed of the crystal rod when the diameter change trend and / or temperature change trend meet the preset adjustment conditions, and when the control start-up time point is met" includes:

[0087] S401, when the current diameter change rate of the crystal rod exceeds the diameter change rate threshold range, simultaneously adjust the heating power of the melt and the lifting speed of the crystal rod.

[0088] In this embodiment, when the calculated real-time diameter change rate exceeds a preset diameter change rate threshold range, a collaborative adjustment strategy is invoked. For example, if the diameter change rate indicates an increase in diameter, the heating power is reduced to cool the solid-liquid interface, while the crystal rod lifting speed is increased to suppress the diameter expansion trend; if the diameter change rate indicates a decrease in diameter, the heating power is increased and the pulling speed is reduced.

[0089] S402, when the current temperature change rate of the melt exceeds the temperature fluctuation threshold range, adjust the heating power of the melt.

[0090] In this embodiment, when the calculated rate of temperature change exceeds the temperature fluctuation threshold range, a single adjustment strategy is invoked. For example, if the rate of temperature change indicates a temperature increase, the heating power is reduced to cool the solid-liquid interface; if the rate of temperature change indicates a temperature decrease, the heating power is increased.

[0091] Optionally, when the current temperature change rate of the melt exceeds the temperature fluctuation threshold range, the heating power of the melt and the lifting speed of the crystal rod can be adjusted simultaneously.

[0092] In the above-mentioned embodiments, the diameter deviation is strongly corrected by adjusting the power and pulling speed in synergy, and the temperature fluctuation is calmed by adjusting the power, covering the main types of disturbances that cause wire breakage, realizing the transformation from trend warning to early suppression, thereby reducing the probability of wire breakage.

[0093] In one embodiment, an implementation of S401 is provided, wherein the lower limit of the diameter change rate threshold range is a first change rate threshold, and the upper limit is a second change rate threshold; as shown... Figure 5 As shown, the above-mentioned "when the current diameter change rate of the crystal rod exceeds the diameter change rate threshold range, simultaneously adjust the heating power of the melt and the lifting speed of the crystal rod" includes:

[0094] S501, if the current diameter change rate corresponding to the diameter change trend is less than the first change rate threshold, then reduce the heating power and increase the lifting speed of the crystal rod.

[0095] In this embodiment, the first rate of change threshold can be negative, representing the rate of change of the diameter of the crystal rod. If the current rate of change of diameter is less than the set first rate of change threshold, that is, the actual thinning rate has exceeded the expected control target, the heating power of the melt is reduced to reduce the heat input of the thermal field to crystal growth, causing the melt temperature at the solid-liquid interface to drop slightly, thereby slowing down the crystal solidification rate. At the same time, the lifting speed of the crystal rod is increased, and the crystal is pulled away from the high temperature region more quickly through the lifting action. The two work together to cause the solid-liquid interface to retreat, effectively suppressing further reduction of diameter and causing the diameter to return to the set standard value.

[0096] Optionally, the first rate of change threshold is used to define a reasonable range of rates of change for the reduction in crystal rod diameter. The range of the first rate of change threshold can be [-5 mm / min, 0). If the current rate of change in diameter is less than the first rate of change threshold, it indicates that the crystal rod diameter is abnormally reduced, and the process parameters need to be adjusted.

[0097] For example, if the current diameter is smaller than the set standard value (278mm), and the first rate of change threshold is -3mm / min, and the diameter changes to 276mm per unit time, then the current diameter change rate is -2mm / min. Since this rate of change is greater than the first rate of change threshold, no changes to the heating power or lifting speed are needed. However, if the set standard value is 278mm, and the first rate of change threshold is -3mm / min, and the diameter changes to 274mm per unit time, then the current diameter change rate is -4mm / min. Since this rate of change is less than the first rate of change threshold, the heating power should be reduced and the crystal rod lifting speed increased. The set standard value for the diameter must be set according to production requirements.

[0098] S502, if the current diameter change rate corresponding to the diameter change trend is greater than the second change rate threshold, then increase the heating power and decrease the crystal rod lifting speed.

[0099] In this embodiment, the second change rate threshold can be a positive value, representing the rate of change of the crystal rod's diameter. If the current diameter change rate is greater than the set second change rate threshold, that is, the actual thickening rate is too fast and has exceeded the expected control target, the heating power of the melt is increased to raise the temperature of the thermal field, providing more heat to the solid-liquid interface and promoting the maintenance or expansion of the melt. At the same time, the lifting speed of the crystal rod is reduced, so that the crystal rod stays in the high-temperature region for a longer time, slowing down the speed at which the crystal rod is pulled away. The two work together to advance the solid-liquid interface, effectively suppressing further increase in diameter and prompting the diameter to return to the set standard value.

[0100] Optionally, the second rate of change threshold is used to define a reasonable range of rates of change for increasing the crystal rod diameter. The range of the second rate of change threshold can be (0, 5 mm / min). If the current rate of change of diameter is greater than the second rate of change threshold, it indicates that the crystal rod diameter has increased abnormally, and the process parameters need to be adjusted.

[0101] For example, if the current diameter is larger than the set standard value (278mm), and the second rate of change threshold is 3mm / min, and the diameter changes to 280mm per unit time, then the current diameter change rate is 2mm / min. Since the current diameter change rate is less than the second rate of change threshold, no changes to the heating power or lifting speed are needed. However, if the set standard value is 278mm, the second rate of change threshold is 3mm / min, and the diameter changes to 283mm per unit time, then the current diameter change rate is 5mm / min. Since the current diameter change rate is greater than the second rate of change threshold, the heating power should be increased and the crystal rod lifting speed decreased. The set standard value for the diameter must be set according to production requirements.

[0102] In the above-mentioned embodiments, a reverse linkage control scheme is preset for the two opposite trends of diameter deviation, which realizes rapid control of crystal growth diameter, ensures the stability of diameter during the constant diameter growth stage, and thus prevents wire breakage caused by diameter loss of control.

[0103] In one embodiment, an implementation of S402 is provided, wherein the lower limit of the temperature fluctuation threshold range is a first fluctuation threshold, and the upper limit is a second fluctuation threshold; as shown... Figure 6 As shown, the above-mentioned "adjusting the heating power of the melt when the current temperature change rate of the melt exceeds the temperature fluctuation threshold range" includes:

[0104] S601, if the current temperature change rate corresponding to the temperature change trend is less than the first fluctuation threshold, then increase the heating power.

[0105] In this embodiment, the first fluctuation threshold can be negative, representing the rate of temperature decrease of the melt. When the rate of temperature change is less than the set first fluctuation threshold, it indicates that the actual cooling rate has exceeded the control target, and the thermal field is rapidly losing heat. To prevent the continuous temperature drop from disrupting the thermal balance of the growth interface, the output of heating power is increased. By enhancing the heat input to the melt, the downward trend of temperature is countered, thereby rapidly slowing down and ultimately reversing the cooling process, allowing the melt temperature to return to and stabilize at the set standard value of liquid temperature. This avoids the abrupt change in crystal growth rate or the surge in thermal stress caused by excessively low temperature, which could lead to wire breakage.

[0106] Optionally, the first fluctuation threshold is used to define a reasonable range for the melt temperature drop. The range of the first fluctuation threshold can be [-5℃ / min, 0). For example, when the current liquid temperature is lower than the set standard value, if the set standard value is 1650℃ / min and the first fluctuation threshold is -2℃ / min, and the temperature changes to 1649℃ / min per unit time, then the current temperature change rate is -1℃ / min, which is greater than the first fluctuation threshold, and no change in heating power is needed. If the set standard value is 1650℃ / min and the first fluctuation threshold is -2℃ / min, and the temperature changes to 1645℃ / min per unit time, then the current temperature change rate is -5℃ / min, which is less than the first fluctuation threshold, and the heating power should be increased. The set standard value for the liquid temperature needs to be set according to production requirements.

[0107] S602, if the current temperature change rate corresponding to the temperature change trend is greater than the second fluctuation threshold, then reduce the heating power.

[0108] In this embodiment, the second fluctuation threshold can be a positive value, representing the rate of temperature change of the melt. When the rate of temperature change is greater than the set second fluctuation threshold, it indicates that the actual heating rate has exceeded the control target, and the heat in the thermal field is accumulating too quickly. To prevent excessively high temperatures from causing intensified melt convection or crystal remelting, the output of heating power is reduced. By reducing the output of the heat source, the heat dissipation in the thermal field is greater than the heat generation, thereby curbing the rapid rise in temperature and causing the melt temperature to steadily drop back to the set standard value of the liquid temperature, ensuring that the crystal continues to grow in a stable thermal environment.

[0109] Optionally, the second fluctuation threshold is used to define a reasonable range for the melt temperature rise. The range of the second fluctuation threshold can be (-5℃ / min, 0). For example, when the current liquid temperature is higher than the set standard value, if the set standard value is 1650℃ / min and the second fluctuation threshold is 2℃ / min, and the temperature changes to 1652℃ / min per unit time, then the current temperature change rate is 2℃ / min, which is not less than the second fluctuation threshold, and no change in heating power is needed. If the set standard value is 1650℃ / min and the second fluctuation threshold is ℃ / min, and the temperature changes to 1654℃ / min per unit time, then the current temperature change rate is 4℃ / min, which is greater than the second fluctuation threshold, and the heating power should be reduced. The set standard value for the liquid temperature needs to be set according to production requirements.

[0110] In the above-mentioned embodiments, the liquid temperature is regulated by power control to stabilize the melt temperature at a set standard value, thereby ensuring the constant thermal environment for crystal growth and avoiding the risk of wire breakage caused by drastic temperature changes.

[0111] In one embodiment, an implementation of the above S201 is provided, wherein the "identification and control start time point" includes: starting from the constant diameter growth stage, determining the moment when the temperature of the melt is first identified as being maintained within the target temperature range for a first preset time and the diameter of the crystal rod is maintained within the target diameter range for a second preset time as the control start time point.

[0112] In this embodiment, after the crystal growth enters the constant diameter growth stage, continuous monitoring and status assessment are performed, i.e., the melt temperature and the crystal rod diameter are continuously monitored, and it is determined whether the melt temperature and the crystal rod diameter simultaneously enter and remain in a stable state. For example, the melt temperature is first identified as consistently stable within a preset target temperature range, and this stable state needs to be maintained for a first preset duration, for example, 30 seconds; simultaneously, the crystal rod diameter is first identified as consistently stable within a preset target diameter range, and this stable state needs to be maintained for a second preset duration, for example, 20 seconds. When it is detected that the above two conditions are simultaneously met at a certain moment, that moment is determined as the control start time point.

[0113] In the above-mentioned embodiments, by setting clear stable state criteria, the control start time point is determined, avoiding unnecessary or erroneous intervention in the early stage when crystal growth is not yet stable, thereby improving the effectiveness and stability of automatic control.

[0114] In one embodiment, the method for preparing the above-mentioned single-crystal silicon rod further includes: continuously heating the molten material to melt at a first power during the melt stage to obtain a melt.

[0115] The heating power includes main heating power and bottom heating power. The main heating power of the first power is 115kW-125kW, and the bottom heating power of the first power is 95kW-105kW.

[0116] In this embodiment, a composite thermal field comprising a main heating power and a bottom heating power is used for heating. The main heating power is set in the range of 115kW to 125kW, while the bottom heating power is set in the range of 95kW to 105kW. This power combination is used to continuously and stably heat the polycrystalline silicon material in the quartz crucible until all the solid silicon material is completely melted, forming a uniform silicon melt that meets the process requirements.

[0117] For example, during the melting stage, the main heating power can be 120kW and the bottom heating power can be 110kW; or, the main heating power can be 123kW and the bottom heating power can be 97kW.

[0118] Optionally, the target holding time for the first power is in the range of (415 min, 425 min).

[0119] Optionally, after the melting stage is completed, the heating power is reduced from the first power to the second power to enter the constant diameter growth stage; wherein, the main heating power of the second power is 75kW-85kW, and the bottom heating power of the second power is 65kW-75kW.

[0120] In this embodiment, after the silicon material is completely melted and the thermal field is homogenized, the thermal power is adjusted to transition to the constant-diameter growth stage of crystal growth. The heating power is reduced from a higher first power used in the melt stage to a second power suitable for stable crystal growth. The main heating power of the second power is adjusted to the range of 85kW to 75kW, while the bottom heating power is adjusted to the range of 75kW to 65kW. This establishes an axial and radial temperature gradient more suitable for the steady-state growth of single crystals.

[0121] For example, after the melting stage is completed, the main heating power can be 80kW and the bottom heating power can be 70kW; or, the main heating power can be 82kW and the bottom heating power can be 68kW.

[0122] Optionally, the target duration of the second power is in the range of [295 min, 305 min].

[0123] Optionally, argon gas is used in the melting stage to remove released impurities and oxygen, with the argon gas flow rate ranging from 175 pm to 185 pm.

[0124] In conventional techniques, the main heating power during the melt stage is between 95kW and 105kW, the bottom heating power is between 85kW and 95kW, and the argon flow rate ranges from 115pm to 125pm. During the crystal growth stage, the main heating power is between 50kW and 60kW, the bottom heating is off, and the bottom heating power is 0. During the shoulder formation stage, the main heating power is reduced to between 40kW and 50kW, the bottom heating is off, and the bottom heating power is 0. During the constant diameter growth stage, the main heating power is maintained between 40kW and 50kW, the bottom heating is off, and the bottom heating power is 0. However, in this embodiment, the main heating power is increased to (115kW, 125kW) and the bottom heating power is increased to (95kW, 105kW) during the melt stage. Compared to conventional techniques, this increases the high-power holding time, thereby releasing impurities and oxygen from the silicon material and crucible earlier, and increasing the argon flow rate further removes the released impurities and oxygen.

[0125] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0126] Based on the same inventive concept, this application also provides an apparatus for preparing a single-crystal silicon rod to implement the above-described method for preparing a single-crystal silicon rod. The solution provided by this apparatus is similar to the solution described in the above-described method. Therefore, the specific limitations of one or more embodiments of the apparatus for preparing a single-crystal silicon rod provided below can be found in the limitations of the method for preparing a single-crystal silicon rod described above, and will not be repeated here.

[0127] In one embodiment, such as Figure 7 As shown, an apparatus for preparing a single-crystal silicon rod is provided, comprising: a detection module 10 and an adjustment module 11, wherein:

[0128] The monitoring module 10 is used to monitor the diameter change trend of the crystal rod and the temperature change trend of the melt during the constant diameter growth stage, and to identify the control start-up time point.

[0129] The adjustment module 11 is used to adjust at least one of the heating power of the melt and the lifting speed of the crystal rod when the diameter change trend and / or temperature change trend meet the preset adjustment conditions and the control start time point is met.

[0130] In one embodiment, the monitoring module 10 includes: an acquisition unit and a calculation unit, wherein:

[0131] The acquisition unit is used to acquire the timing data of the crystal rod's diameter and the timing data of the melt's temperature.

[0132] The calculation unit is used to calculate the rate of change of diameter time series data per unit time to obtain the diameter change trend; and to calculate the rate of change of temperature time series data per unit time to obtain the temperature change trend.

[0133] In one embodiment, the adjustment module 11 includes: a first adjustment unit and a second adjustment unit, wherein:

[0134] The first adjustment unit is used to simultaneously adjust the heating power of the melt and the lifting speed of the crystal rod when the current diameter change rate of the crystal rod exceeds the diameter change rate threshold range.

[0135] The second adjustment unit is used to adjust the heating power of the melt when the current temperature change rate of the melt exceeds the temperature fluctuation threshold range.

[0136] In one embodiment, the first adjustment unit is specifically used to reduce the heating power and increase the crystal rod lifting speed when the current diameter change rate corresponding to the diameter change trend is less than a first change rate threshold; and to increase the heating power and decrease the crystal rod lifting speed when the current diameter change rate corresponding to the diameter change trend is greater than a second change rate threshold.

[0137] In one embodiment, the second adjustment unit is specifically used to increase the heating power when the current temperature change rate corresponding to the temperature change trend is less than the first fluctuation threshold, and to decrease the heating power when the current temperature change rate corresponding to the temperature change trend is greater than the second fluctuation threshold.

[0138] In one embodiment, the monitoring module 10 includes: an identification unit, configured to determine the moment when the temperature of the melt is first identified as being maintained within the target temperature range for a first preset duration and the diameter of the crystal rod is maintained within the target diameter range for a second preset duration, starting from the beginning of the constant diameter growth stage, as the control start time point.

[0139] In one embodiment, the above-mentioned single-crystal silicon rod preparation apparatus further includes: a heating module for continuously heating the molten material to melt at a first power during the melt stage to obtain a melt; wherein the heating power includes a main heating power and a bottom heating power, the main heating power of the first power is 115kW-125kW, and the bottom heating power of the first power is 95kW-105kW.

[0140] In one embodiment, the heating module is further configured to reduce the heating power from the first power to the second power after the melting stage is completed, and enter the constant diameter growth stage; wherein the main heating power of the second power is 75kW-85kW, and the bottom heating power of the second power is 65kW-75kW.

[0141] Each module in the aforementioned single-crystal silicon rod fabrication apparatus can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the operations corresponding to each module.

[0142] In one embodiment, this application provides a silicon wafer, which is formed by preparing and slicing using any of the above-described methods for preparing single-crystal silicon rods.

[0143] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0144] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for preparing a single-crystal silicon rod, characterized in that, The method includes: during the constant diameter growth stage: Monitor the diameter change trend of the crystal rod and the temperature change trend of the melt to identify the control start-up time point; When the diameter change trend and / or the temperature change trend meet the preset adjustment conditions, and when the control start time point is met, at least one of the heating power of the melt and the lifting speed of the crystal rod is adjusted.

2. The method for preparing a single-crystal silicon rod according to claim 1, characterized in that, The step of adjusting at least one of the heating power of the melt and the lifting speed of the crystal rod when the diameter change trend and / or the temperature change trend meet preset adjustment conditions, and when the control start time point is met, includes: When the current diameter change rate of the crystal rod exceeds the diameter change rate threshold range, the heating power of the melt and the lifting speed of the crystal rod are adjusted simultaneously. When the current temperature change rate of the melt exceeds the temperature fluctuation threshold range, the heating power of the melt is adjusted.

3. The method for preparing a single-crystal silicon rod according to claim 2, characterized in that, The lower limit of the diameter change rate threshold range is a first change rate threshold, and the upper limit is a second change rate threshold; when the current diameter change rate of the crystal rod exceeds the diameter change rate threshold range, simultaneously adjusting the heating power of the melt and the lifting speed of the crystal rod includes: If the current diameter change rate corresponding to the diameter change trend is less than the first change rate threshold, then reduce the heating power and increase the lifting speed of the crystal rod. If the current diameter change rate corresponding to the diameter change trend is greater than the second change rate threshold, then increase the heating power and decrease the crystal rod lifting speed.

4. The method for preparing a single-crystal silicon rod according to claim 2, characterized in that, The lower limit of the temperature fluctuation threshold range is the first fluctuation threshold, and the upper limit is the second fluctuation threshold; When the current temperature change rate of the melt exceeds the temperature fluctuation threshold range, adjusting the heating power of the melt includes: If the current temperature change rate corresponding to the temperature change trend is less than the first fluctuation threshold, then increase the heating power; If the current temperature change rate corresponding to the temperature change trend is greater than the second fluctuation threshold, then reduce the heating power.

5. The method for preparing a single-crystal silicon rod according to claim 1, characterized in that, The monitoring of the diameter variation trend of the crystal rod and the temperature variation trend of the melt includes: Obtain the time-series data of the diameter of the crystal rod and the time-series data of the temperature of the melt; The rate of change of the diameter time series data per unit time is calculated to obtain the diameter change trend; the rate of change of the temperature time series data per unit time is calculated to obtain the temperature change trend.

6. The method for preparing a single-crystal silicon rod according to any one of claims 1-5, characterized in that, The identified control activation time point includes: Once the constant diameter growth stage begins, the moment when the temperature of the melt is first maintained within the target temperature range for a first preset duration and the diameter of the crystal rod is maintained within the target diameter range for a second preset duration is determined as the control start time.

7. The method for preparing a single-crystal silicon rod according to any one of claims 1-5, characterized in that, The method further includes: continuously heating the molten material to melt at a first power during the melt stage to obtain the melt; The heating power includes main heating power and bottom heating power. The main heating power of the first power is 115kW-125kW, and the bottom heating power of the first power is 95kW-105kW.

8. The method for preparing a single-crystal silicon rod according to claim 6, characterized in that, After the melting stage is completed, the heating power is reduced from the first power to the second power, and the constant diameter growth stage begins. The main heating power of the second power is 75kW-85kW, and the bottom heating power of the second power is 65kW-75kW.

9. An apparatus for preparing a single-crystal silicon rod, characterized in that, The device includes: The monitoring module is used to monitor the diameter change trend of the crystal rod and the temperature change trend of the melt during the constant diameter growth stage, and to identify the control start-up time point. An adjustment module is used to adjust at least one of the heating power of the melt and the lifting speed of the crystal rod when the diameter change trend and / or the temperature change trend meet preset adjustment conditions and the adjustment start time point is met.

10. A silicon wafer, characterized in that, The silicon wafer is prepared and diced using the method for preparing a single-crystal silicon rod according to any one of claims 1-8.

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