Crystal furnace control method and system based on feedback regulation

Abstract

The invention discloses a crystal furnace control method and system based on feedback regulation, and relates to the technical field of crystal furnace control, and the method comprises the steps: controlling a seed chuck to execute a predetermined detection action, and obtaining the rotation feedback force of the seed chuck and a seed head region image; determining stress interference uniformity based on the feedback force in the rotation direction, and analyzing stress growth characteristics of the growing crystal based on the seed crystal head area image; determining a stress interference characterization value based on the stress interference uniformity and the stress growth characteristics, and judging the stress interference type of the current growing crystal; determining crystal growth parameters based on the stress interference type of the currently grown crystal; and controlling the crystal furnace based on the target crystal growth parameter, monitoring the contour change condition of the growing crystal after the target time period and the temperature change condition along the pulling direction, and judging whether the crystal growth process meets a preset standard or not. According to the invention, the uniformity and growth efficiency of crystals can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal furnace control, and particularly to a crystal furnace control method and system based on feedback regulation. Background Art

[0002] The Czochralski method, also known as the Cz method, is a method invented by J. Czochralski in 1917 for pulling high-quality single crystals from a melt. In the 1960s, the Czochralski method was further developed into a more advanced shaped crystal growth method - the melt guiding mold method, a growth technique for directly pulling crystals with various cross-sectional shapes from a melt, which not only eliminates the heavy machining of artificial crystals in industrial production but also effectively saves raw materials and reduces production costs. The Czochralski crystal furnace adjusts the thermal field through main and auxiliary electromagnetic induction coils and a retractable heat shield, and is commonly used to prepare bulk crystals. Due to the real-time changes in various operating environments inside the crystal furnace, it is often difficult to maintain the real-time operating state inside the crystal furnace stable and controllable, resulting in poor uniformity in the growth of crystals. In order to ensure the uniformity of the crystals, there is a situation of sacrificing the crystal growth efficiency, which disrupts the operating state of the crystal furnace. In order to maintain the stable operating state of the crystal furnace and improve the uniformity and growth efficiency of the crystals, accurate control of the crystal furnace is required. In the prior art, the crystal furnace control system does not optimize the crystal growth parameters but directly uses the crystal growth parameters obtained by rough calculation. This method has disadvantages such as low control accuracy, poor control effect, and poor control stability, which will not only reduce the growth efficiency of the crystal furnace but also damage the uniformity of the crystals.

[0003] Chinese Patent Application Publication No. CN119320988A discloses a crystal furnace operation control method, device, equipment, and medium. The control method includes: obtaining a first image inside the crystal furnace; the first image is used to reflect the state of the seed crystal held at the end of the seed crystal holder; when the seed crystal held by the seed crystal holder has contacted the melt raw material, obtaining a first clamping force applied by the seed crystal holder to the seed crystal; determining whether the first clamping force is greater than a preset clamping threshold. If so, obtaining the crystal growth type and calling a preset speed calibration database to obtain a rotation speed corresponding to the first clamping force and the crystal type; if not, sending a first prompt signal for prompting the user that the seed crystal has a risk of falling off.

[0004] The prior art has the following problems: In the prior art, only the clamping force of the seed crystal by the seed crystal holder and the crystal growth type are used to determine the corresponding rotation speed, and the crystal growth process is not monitored. It is impossible to perform feedback regulation according to the changes during the crystal growth process, and it is difficult to ensure the uniformity and growth efficiency of the crystals. Summary of the Invention

[0005] To this end, the present invention provides a crystal furnace control method and system based on feedback regulation to overcome the problems in the prior art that it is difficult to ensure the uniformity and growth efficiency of crystals.

[0006] To achieve the above object, on the one hand, the present invention provides a crystal furnace control method based on feedback regulation, including: Controlling the seed crystal chuck to perform a predetermined detection action to obtain the rotational feedback force of the seed crystal chuck and the image of the seed crystal head area, wherein the predetermined detection action includes controlling the seed crystal chuck to rotate a predetermined number of turns at a predetermined height; Determining the stress interference uniformity based on the rotational feedback force, and analyzing the stress growth characteristics of the growing crystal based on the image of the seed crystal head area, where the stress growth characteristics include the texture spacing and the maximum width of the growing crystal on the melt surface; Determining the stress interference characterization value based on the stress interference uniformity and the stress growth characteristics, and determining the stress interference category of the currently growing crystal, where the stress interference category includes a strong stress interference influence category and a weak stress interference influence category; If the stress interference category of the currently growing crystal is the strong stress interference influence category, then determining the target crystal growth parameters based on the stress interference characterization value and the initial crystal growth parameters; If the stress interference category of the currently growing crystal is the weak stress interference influence category, then determining the initial crystal growth parameters as the target crystal growth parameters; Controlling the crystal furnace based on the target crystal growth parameters, monitoring the contour change of the growing crystal and the temperature change along the pulling direction after the target time period, and determining whether the crystal growth process meets the preset standard. If not, re-determining the crystal growth parameters; Among them, the crystal growth parameters include the pulling speed and the rotation speed.

[0007] Further, the determining the stress interference uniformity includes: Constructing a feedback force time-domain curve based on the rotational feedback force and identifying the specific rising segment of the feedback force time-domain curve; Determining the stress interference uniformity based on the smoothness of the specific rising segment of the feedback force time-domain curve.

[0008] Further, the determining the stress interference characterization value includes: Determining the first characteristic value based on the comparison result of the stress interference uniformity and the preset uniformity; Determining the second characteristic value based on the texture spacing and the maximum width of the growing crystal on the melt surface; Determining the stress interference characterization value based on the first characteristic value and the second characteristic value.

[0009] Further, determining the stress interference category of the currently growing crystal includes: Determining the stress interference category of the currently growing crystal based on the comparison result between the stress interference characterization value and a preset characterization value; Wherein, if the stress interference characterization value is greater than the preset characterization value, it is determined that the stress interference category of the currently growing crystal is a strong stress interference influence category; If the stress interference characterization value is less than or equal to the preset characterization value, it is determined that the stress interference category of the currently growing crystal is a weak stress interference influence category.

[0010] Further, determining the target crystal growth parameters based on the stress interference characterization value and the initial crystal growth parameters includes: Determining a characterization adjustment parameter based on the comparison result between the stress interference characterization value and the preset characterization value; Determining the target crystal growth parameters based on the characterization adjustment parameter and the initial crystal growth parameters.

[0011] Further, determining whether the crystal growth process meets a preset standard includes: Determining a profile characteristic value based on the profile change of the grown crystal after the target time period; Determining a temperature characteristic value based on the temperature change along the pulling direction; Determining whether the crystal growth process meets the preset standard based on the profile characteristic value and the temperature characteristic value.

[0012] Further, determining the profile characteristic value includes: Determining a number of profile mutation regions based on the profile change of the grown crystal after the target time period; Determining the profile characteristic value based on the area and the maximum diameter length of each profile mutation region.

[0013] Further, determining the temperature characteristic value includes: Constructing a seed-melt temperature gradient change curve based on the temperature change along the pulling direction; Determining a number of temperature key points based on the seed-melt temperature gradient change curve; Determining the temperature characteristic value based on the comparison result of each temperature key point.

[0014] Further, the crystal growth process meeting the preset standard means that the profile characteristic value is less than the preset profile characteristic value and the temperature characteristic value is less than the preset temperature characteristic value.

[0015] On the other hand, the present invention also provides a crystal furnace control system, including: A pre-detection module, which is used to control the seed crystal chuck to perform a predetermined detection action, obtain the rotational feedback force of the seed crystal chuck and the image of the seed crystal head area, wherein the predetermined detection action includes controlling the seed crystal chuck to rotate a predetermined number of turns while maintaining a predetermined height; A stress interference analysis module, which is used to determine the stress interference uniformity based on the rotational feedback force, analyze the stress growth characteristics of the growing crystal based on the image of the seed crystal head area, and determine the stress interference characterization value based on the stress interference uniformity and the stress growth characteristics, and determine the stress interference category of the current growing crystal, wherein the stress growth characteristics include the texture spacing and the maximum width of the growing crystal on the melt surface, and the stress interference category includes a strong stress interference influence category and a weak stress interference influence category; A parameter determination module, which is used to determine the target crystal growth parameters based on the stress interference characterization value and the initial crystal growth parameters if the stress interference category of the current growing crystal is the strong stress interference influence category; if the stress interference category of the current growing crystal is the weak stress interference influence category, determine the initial crystal growth parameters as the target crystal growth parameters; wherein the crystal growth parameters include the pulling speed and the rotation speed; A monitoring and analysis module, which is used to grow crystals based on the target crystal growth parameters, monitor the contour change of the growing crystal and the temperature change along the pulling direction after a target time period, and determine whether the crystal growth process meets the preset standard, wherein if not, re-determine the crystal growth parameters.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows. By controlling the seed crystal chuck to perform a predetermined detection action, the stress loading conditions are ensured to be consistent, the rotational feedback force of the seed crystal chuck can be accurately determined, and the stress growth characteristics of the growing crystal can be accurately analyzed according to the image of the seed crystal head area, and the stress distribution can be quantified, providing an initial basis for subsequent stress analysis. By fusing the mechanical feedback (stress interference uniformity) with the morphological characteristics (stress growth characteristics of the growing crystal) to determine the stress interference characterization value and determine the stress interference category of the current growing crystal, the stress distribution can be comprehensively and quantitatively evaluated, and classification control can be realized, reducing the risk of misjudgment. Determining the crystal growth parameters based on the stress interference category of the current growing crystal can realize adaptive parameter optimization. The strong stress interference influence category is vulnerable to stress, which may lead to poor uniformity of crystal growth during the pulling process. Therefore, the crystal growth parameters are adjusted based on the stress interference characterization value to improve the uniformity of crystal growth. The weak stress interference influence category is not easily affected by stress, and growing crystals based on the initial crystal growth parameters can reduce the control complexity, avoid process fluctuations caused by excessive adjustment, and improve the growth efficiency. By monitoring the contour change of the growing crystal and the temperature change along the pulling direction during the crystal growth process to determine whether the crystal growth process meets the preset standard, real-time feedback control can be realized, abnormal rapid response can be achieved, defect accumulation can be avoided, the uniformity of crystal growth can be improved, and the crystal quality can be improved.

[0017] Furthermore, the present invention constructs a time-domain curve of the feedback force and identifies a specific rising segment of the time-domain curve. The specific rising segment indicates the region where the transient stress gradually increases during the rotation of the seed chuck. Usually, in the initial stage, the stress interference uniformity is determined by the smoothness of the specific rising segment, which can improve the calculation efficiency and accuracy. The stress interference uniformity can reflect the degree of stress change, realizing precise evaluation.

[0018] Furthermore, the present invention determines a number of contour mutation regions based on the contour change of the grown crystal after the target time period, can capture the crystal growth change trend in real time, realizes the correlation analysis of multiple contour mutation regions, and determines the contour characteristic value based on the area and the maximum diameter length of each contour mutation region, which can quantitatively evaluate the degree of contour change. As one of the evaluation criteria, it can improve the uniformity of crystal growth.

[0019] Furthermore, the present invention constructs a temperature gradient change curve of the seed-melt, can map the crystal thermal field distribution in real time. Through multi-point temperature monitoring along the pulling direction (i.e., the crystal growth direction), a continuous temperature gradient curve can be constructed. The temperature gradient directly affects the crystal growth rate and stress distribution. The slope change of the curve can reveal local thermal field anomalies. By identifying the temperature key points, the key positions affecting crystal growth can be located, reducing the amount of data processing. By determining the temperature characteristic value based on the temperature key points, the stability of the thermal field can be quantitatively evaluated, reflecting the fluctuation degree of the temperature gradient. As one of the evaluation criteria, it can improve the uniformity of crystal growth. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic flow chart of the crystal furnace control method based on feedback regulation according to an embodiment of the present invention; Figure 2 is a schematic flow chart of determining the stress interference characterization value according to an embodiment of the present invention; Figure 3 is a logical decision diagram for determining the stress interference category of the currently grown crystal according to an embodiment of the present invention; Figure 4 is a structural block diagram of the crystal furnace control system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] In order to make the objectives and advantages of the present invention clearer, the present invention will be further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principle of the present invention and do not limit the protection scope of the present invention.

[0023] It should be noted that in the description of the present invention, the terms indicating directions or positional relationships such as "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings. This is only for convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0024] In addition, it should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0025] In the implementation, the process of pulling and growing single crystals includes raw material preparation and furnace loading (crushing and cleaning the raw materials, removing impurities, putting the raw materials into the crystal furnace, fixing the seed crystal on the seed crystal chuck, evacuating and filling with high-purity protective gas to protect the melt), heating and melting the materials (heating the crystal furnace to completely melt the raw materials to form a stable melt), seeding (lowering the seed crystal to the surface of the melt, controlling the rotation of the seed crystal to form a stable solid-liquid interface and avoiding the generation of multiple crystal nuclei), necking (increasing the pulling speed to reduce the diameter of the crystal neck and eliminate the extension of the seed crystal dislocation), shoulder opening (lowering the pulling speed and increasing the rotation speed to gradually expand the crystal diameter to the target value), equal-diameter growth (maintaining the pulling speed and rotation speed to keep the crystal diameter stable), and ending (lowering the pulling speed and rotation speed to gradually reduce the tail of the crystal to a sharp point, avoiding fracture caused by stress concentration, turning off the heating power supply, and taking out the crystal after it cools to room temperature with the furnace).

[0026] Please refer to Figure 1 as shown, which is a schematic flowchart of the crystal furnace control method based on feedback regulation according to an embodiment of the present invention; an embodiment of the present invention provides a crystal furnace control method and system based on feedback regulation, including: Step S1, controlling the seed crystal chuck to perform a predetermined detection action, and obtaining the rotational feedback force of the seed crystal chuck and the image of the seed crystal head area, wherein the predetermined detection action includes controlling the seed crystal chuck to maintain a predetermined height and rotate a predetermined number of turns; In implementation, the seed crystal chuck is a device used to fix the seed crystal during the crystal growth process, and the seed crystal is stably fixed in the crystal furnace through mechanical clamping. The rotational feedback force is the acting force opposite to the rotational motion direction generated during the rotation of the seed crystal chuck holding the seed crystal.

[0027] In implementation, the predetermined height is the distance between the bottom of the seed crystal and the melt interface, the predetermined number of turns is the number of turns of the seed crystal chuck holding the seed crystal to rotate, and the predetermined detection action is to maintain the rotation for a predetermined number of turns at the predetermined height after lifting with the initial crystal growth parameters after the seed crystal contacts the melt. The actual implementer can determine the predetermined height and the predetermined number of turns based on the actual situation or limited experiments. Preferably, the value range of the predetermined height is 5 mm to 20 mm, and the value range of the predetermined number of turns is 5 to 8.

[0028] In implementation, there is no specific limitation on the method and equipment for obtaining the rotational feedback force of the seed crystal chuck and the image of the seed crystal head area. For example, a strain gauge is pasted on the rotation axis of the seed crystal chuck. When a torque acts, the resistance change of the strain gauge is converted into a voltage signal through a Wheatstone bridge, or the rotational feedback force is calculated by monitoring the change of the current of the motor driving the rotation of the seed crystal and combining the motor torque constant. A number of image devices are arranged inside the crystal furnace, and the image of the seed crystal head area includes the image of the connection part between the seed crystal and the crystal, that is, the image of the initial crystal growth area.

[0029] In implementation, the rotational feedback force of the seed crystal chuck and the image of the seed crystal head area are collected once every preset time interval. Preferably, the value range of the preset time interval is set to 2 s to 5 s.

[0030] Step S2, determining the stress interference uniformity based on the rotational feedback force, and analyzing the stress growth characteristics of the growing crystal based on the image of the seed crystal head area, where the stress growth characteristics include the texture spacing and the maximum width of the growing crystal on the melt surface; In implementation, the texture spacing and the maximum width of the growing crystal on the melt surface can be determined based on the images captured by a number of image devices arranged inside the crystal furnace, and there is no limitation on the specific determination method.

[0031] Step S3, determining a stress interference characterization value based on the stress interference uniformity and the stress growth characteristics, and determining the stress interference category of the currently growing crystal, where the stress interference category includes a strong stress interference influence category and a weak stress interference influence category; If the stress interference category of the currently growing crystal is the strong stress interference influence category, then determining the target crystal growth parameters based on the stress interference characterization value and the initial crystal growth parameters; If the stress interference category of the currently growing crystal is the weak stress interference influence category, then determining the initial crystal growth parameters as the target crystal growth parameters; Step S4: Control the crystal furnace based on the target crystal growth parameters, monitor the profile change of the grown crystal and the temperature change along the pulling direction after a target time period, and determine whether the crystal growth process meets the preset standard. If not, re-determine the crystal growth parameters. Among them, the crystal growth parameters include the pulling speed and the rotation speed.

[0032] In implementation, if not, re-execute step S1.

[0033] The present invention controls the seed chuck to perform a predetermined detection action, ensures consistent stress loading conditions, can accurately determine the rotational feedback force of the seed chuck, and can accurately analyze the stress growth characteristics of the grown crystal based on the image of the seed head region, can quantify the stress distribution, and provides an initial benchmark for subsequent stress analysis. By fusing the mechanical feedback (stress interference uniformity) with the morphological characteristics (stress growth characteristics of the grown crystal) to determine the stress interference characterization value and determine the stress interference category of the current grown crystal, it can comprehensively quantify and evaluate the stress distribution and achieve classification control, reducing the risk of misjudgment. Determining the crystal growth parameters based on the stress interference category of the current grown crystal can adaptively optimize the parameters. The stress interference strong influence category is susceptible to stress, which may lead to poor uniformity of crystal growth during the pulling process. Therefore, the crystal growth parameters are adjusted based on the stress interference characterization value to improve the uniformity of crystal growth. The stress interference weak influence category is not easily affected by stress. Crystal growth is carried out based on the initial crystal growth parameters, which can reduce the control complexity, avoid process fluctuations caused by excessive adjustment, and improve the growth efficiency. By monitoring the profile change of the grown crystal and the temperature change along the pulling direction during the crystal growth process to determine whether the crystal growth process meets the preset standard, it can provide real-time feedback control, achieve rapid response to anomalies, avoid defect accumulation, improve the uniformity of crystal growth, and improve the crystal quality.

[0034] Specifically, in step S2, the determination of the stress interference uniformity includes: Step S21: Construct a feedback force time-domain curve based on the rotational feedback force, and identify the specific rising segment of the feedback force time-domain curve. Step S22: Determine the stress interference uniformity based on the smoothness of the specific rising segment of the feedback force time-domain curve.

[0035] In implementation, a feedback force time-domain curve is constructed based on the rotational feedback force, with the acquisition time as the abscissa and the rotational feedback force as the ordinate, and the region where the slope of the feedback force time-domain curve is greater than the preset slope and the duration is greater than the preset duration is determined as the specific rising segment.

[0036] In implementation, the smoothness of the specific rising segment is determined based on the fluctuation of the difference in the rotational feedback force at adjacent acquisition times in the specific rising segment. For example, the rotational feedback forces in the specific rising segment are: YJ1, YJ2, …, YJ i , …, YJ n , then the smoothness S of the specific rising segment = (∑ n i=1 ((YJ i+1 - YJ i ) - (∑ n i=1 (YJ i+1 - YJ i ) / n)) 2 ) / n, where i = 1, 2, …, n, n is the number of acquisitions in the specific rising segment, YJ i is the rotational feedback force at the i-th acquisition time, and the smoothness of the specific rising segment is determined as the stress interference uniformity.

[0037] In implementation, the actual implementer can determine the preset slope based on the average slope of the specific rising segments of the rotational feedback force curves that pass the qualification test in the historical data, and the actual implementer can set the preset duration based on the average duration of the specific rising segments of the rotational feedback force curves that pass the qualification test in the historical data. Preferably, the value range of the preset slope is set to 0.8 - 1.5, and the value range of the preset duration is set to 20s - 30s.

[0038] The present invention constructs a feedback force time-domain curve and identifies the specific rising segment of the time-domain curve. The specific rising segment indicates the region where the transient stress gradually rises during the rotation of the seed chuck. Usually, in the initial stage, the stress interference uniformity is determined by the smoothness of the specific rising segment, which can improve the calculation efficiency and accuracy. The stress interference uniformity can reflect the degree of stress change and achieve accurate evaluation.

[0039] Please refer to Figure 2 shown, which is a schematic flow chart for determining the stress interference characterization value in an embodiment of the present invention; specifically, in the step S3, the determination of the stress interference characterization value includes: Step S31, determining a first eigenvalue based on the comparison result between the stress interference uniformity and the preset uniformity; Step S32, determining a second eigenvalue based on the texture spacing and the maximum width of the growing crystal on the melt surface; Step S33, determining the stress interference characterization value based on the first eigenvalue and the second eigenvalue.

[0040] In implementation, the stress interference uniformity reflects the degree of uniformity of the stress distribution during crystal growth. The lower the stress interference uniformity, the more uneven the stress distribution, indicating a greater stress concentration inside the crystal, which will lead to more serious stress interference problems. That is to say, the stress interference characterization value is negatively correlated with the stress interference uniformity. The smaller the stress interference uniformity, the larger the stress interference characterization value. A smaller texture spacing indicates that the stress changes during crystal growth are more frequent and intense, the stress distribution inside the crystal is more complex, the stress interference phenomenon is more serious, and the stress interference characterization value is negatively correlated with the texture spacing. The smaller the texture spacing, the larger the stress interference characterization value. The maximum width of the growing crystal on the melt surface reflects the lateral expansion of the crystal during growth. A larger maximum width means that the melt flow and heat transfer are more complex, and the external influencing factors on the crystal increase, resulting in an aggravation of the stress interference problem. The stress interference characterization value is positively correlated with the maximum width of the growing crystal on the melt surface. The larger the maximum width of the growing crystal on the melt surface, the larger the stress interference characterization value.

[0041] In implementation, the ratio of the stress interference uniformity to the preset uniformity can be determined as the first eigenvalue, the ratio of the maximum width of the growing crystal on the melt surface to the texture spacing can be determined as the second eigenvalue, and the ratio of the second eigenvalue to the first eigenvalue can be determined as the stress interference characterization value. For example, the first eigenvalue YT = GD / YD, the second eigenvalue ET = ZK / WJ, and the stress interference characterization value YB = YT / ET, where GD is the stress interference uniformity, YD is the preset uniformity, ZK is the maximum width of the growing crystal on the melt surface, and WJ is the texture spacing.

[0042] In implementation, the actual implementer can set the preset uniformity based on the average value of the stress interference uniformity that passes the qualification test in the historical data. Preferably, the value range of the preset uniformity is set to 0.8 - 2.

[0043] Please refer to Figure 3 as shown, which is the logical decision diagram for determining the stress interference category of the current growing crystal in the embodiment of the present invention; specifically, in the step S3, determining the stress interference category of the current growing crystal includes: Determining the stress interference category of the current growing crystal based on the comparison result between the stress interference characterization value and the preset characterization value; Among them, if the stress interference characterization value is greater than the preset characterization value, it is determined that the stress interference category of the current growing crystal is the strong stress interference influence category; If the stress interference characterization value is less than or equal to the preset characterization value, it is determined that the stress interference category of the current growing crystal is the weak stress interference influence category.

[0044] In implementation, the actual implementer can set a preset characterization value based on the actual situation or the mean value of the stress interference characterization values that pass the qualification test in historical data. Preferably, the value range of the preset characterization value is set to 1.2 to 1.8.

[0045] Specifically, in the step S4, the determining the target crystal growth parameters based on the stress interference characterization value and the initial crystal growth parameters includes: Step S41, determining a characterization adjustment parameter based on the comparison result between the stress interference characterization value and the preset characterization value; Step S42, determining the target crystal growth parameters based on the characterization adjustment parameter and the initial crystal growth parameters.

[0046] In implementation, the ratio of the stress interference characterization value to the preset characterization value is determined as the characterization adjustment parameter. For the stress interference strong influence category, if the characterization adjustment parameter is greater than 1, then the ratio of the pulling speed to the characterization adjustment parameter is determined as the target pulling speed, and the product of the rotation speed and the characterization adjustment parameter is determined as the target rotation speed.

[0047] In implementation, the initial crystal growth parameters can be determined based on the comparison result between the preset crystal growth parameters and the first eigenvalue. For example, the product of the preset pulling speed and the first eigenvalue is determined as the initial pulling speed, and the product of the preset rotation speed and the first eigenvalue is determined as the initial rotation speed.

[0048] In implementation, the actual implementer can set the preset pulling speed and the preset rotation speed based on the actual situation. Preferably, the value range of the preset pulling speed is set to 1 mm / min to 3 mm / min, and the preset rotation speed is 10 rpm to 30 rpm.

[0049] Specifically, in the step S5, the determining whether the crystal growth process meets the preset standard includes: Step S51, determining a contour feature value based on the contour change situation of the grown crystal after the target time period; Step S52, determining a temperature feature value based on the temperature change situation along the pulling direction; Step S53, determining whether the crystal growth process meets the preset standard based on the contour feature value and the temperature feature value.

[0050] Specifically, in the step S51, the determining the contour feature value includes: Step S511, determining a number of contour mutation regions based on the contour change situation of the grown crystal after the target time period; Step S512, determining the contour feature value based on the area and the maximum diameter length of each contour mutation region.

[0051] In implementation, the contour change of the growing crystal is the change difference of the outer contour of the growing crystal after the target time period. The surface of the growing crystal is divided into several regions along the pulling direction, and the ratio of the maximum diameter (the maximum distance between any two region edge points) to the minimum diameter (the distance between two region edge points in the direction perpendicular to the maximum diameter) of each region is determined as the third eigenvalue, and the curvature of each region is determined as the fourth eigenvalue. If the third eigenvalue corresponding to any region is greater than the preset ratio and the fourth eigenvalue is greater than the preset curvature, the corresponding region is determined as the contour mutation region.

[0052] In implementation, the ratio of the maximum area of each contour mutation region to the maximum diameter length is determined as the contour eigenvalue.

[0053] In implementation, the actual implementer can set the preset ratio based on the actual situation or based on the ratio of the maximum diameter to the minimum diameter of each region of the crystal that passes the qualification test in the historical data. The actual implementer can set the preset curvature based on the actual situation or based on the curvature of the crystal that passes the qualification test in the historical data. Preferably, the value range of the preset ratio is 0.01 - 0.1, and the value range of the preset curvature is set to 0.5 mm - 1 mm.

[0054] The present invention can determine several contour mutation regions based on the contour change of the growing crystal after the target time period, can capture the crystal growth change trend in real time, realize the correlation analysis of multiple contour mutation regions, and determine the contour eigenvalue based on the region area and the maximum diameter length of each contour mutation region, which can quantitatively evaluate the contour change degree. As one of the judgment criteria, it can improve the uniformity of crystal growth.

[0055] Specifically, in the step S52, the determining the temperature eigenvalue includes: Step S521, constructing a seed-melt temperature gradient change curve based on the temperature change along the pulling direction; Step S522, determining several temperature key points based on the seed-melt temperature gradient change curve; Step S523, determining the temperature eigenvalue based on the comparison result of each temperature key point.

[0056] In implementation, the temperature change is the temperature difference of each position of the crystal along the pulling direction. Several temperature measurement points are set along the pulling direction, and the temperature measurement method is not specifically limited. For example, a thermocouple or an infrared thermal imager. The axial gradient is: T = (T j+1 - T j ) / (z j+1 - z j ), z j is the distance between the jth temperature measurement point and the set point along the pulling direction, and T jis the temperature at the j-th temperature measurement point along the pulling direction, where j = 1, 2, …, m - 1, and m is the number of temperature measurement points. Here, the set point is the crystal growth end point near the first temperature measurement point. In actual application, the actual implementer can set the number of temperature measurement points according to the actual situation or the crystal length.

[0057] In implementation, the position point with a gradient change rate of 0 is determined as the temperature key point, and the standard deviation of the temperatures of several temperature key points is determined as the temperature characteristic value.

[0058] The present invention can construct a seed-melt temperature gradient change curve to map the crystal thermal field distribution in real time. Through multi-point temperature monitoring along the pulling direction (i.e., the crystal growth direction), a continuous temperature gradient curve can be constructed. The temperature gradient directly affects the crystal growth rate and stress distribution. The slope change of the curve can reveal local thermal field anomalies. By identifying the temperature key points, the key positions affecting crystal growth can be located, reducing the amount of data processing. By determining the temperature characteristic value based on the temperature key points, the stability of the thermal field can be quantitatively evaluated, reflecting the fluctuation degree of the temperature gradient. As one of the evaluation criteria, it can improve the uniformity of crystal growth.

[0059] Specifically, if the crystal growth process meets the preset standard, there is no need to re-determine the crystal growth parameters; wherein, the preset standard is that the profile characteristic value is less than the preset profile characteristic value and the temperature characteristic value is less than the preset temperature characteristic value.

[0060] In implementation, the actual implementer can set the preset profile characteristic value based on the actual situation or the average value of the profile characteristic values of the crystals passing the qualification test in historical data. The actual implementer can set the preset temperature characteristic value based on the actual situation or the average value of the temperature characteristic values of the crystals passing the qualification test in historical data. Preferably, the value range of the preset profile characteristic value is set to 0.5 - 1, and the value range of the preset temperature characteristic value is set to 0.1 - 0.3.

[0061] Please refer to Figure 4 as shown, which is the structural block diagram of the crystal furnace control system according to the embodiment of the present invention; The embodiment of the present invention also provides a crystal furnace control system, including: A pre-detection module, configured to control the seed chuck to perform a predetermined detection action, and obtain the rotational feedback force of the seed chuck and the image of the seed head area. Here, the predetermined detection action includes controlling the seed chuck to maintain a predetermined height and rotate a predetermined number of turns; A stress interference analysis module, which is used to determine the stress interference uniformity based on the rotation feedback force, analyze the stress growth characteristics of the growing crystal based on the seed head region image, and determine the stress interference characterization value based on the stress interference uniformity and the stress growth characteristics, and determine the stress interference category of the current growing crystal, where the stress growth characteristics include the texture spacing and the maximum width of the growing crystal on the melt surface, and the stress interference category includes a strong stress interference influence category and a weak stress interference influence category; A parameter determination module, which is used to determine the target crystal growth parameters based on the stress interference characterization value and the initial crystal growth parameters if the stress interference category of the current growing crystal is the strong stress interference influence category; and determine the initial crystal growth parameters as the target crystal growth parameters if the stress interference category of the current growing crystal is the weak stress interference influence category; where the crystal growth parameters include the pulling speed and the rotation speed; A monitoring and analysis module, which is used to grow a crystal based on the target crystal growth parameters, monitor the contour change of the growing crystal and the temperature change along the pulling direction after a target time period, and determine whether the crystal growth process meets a preset standard, where if it does not meet the standard, the crystal growth parameters are re-determined.

[0062] Specifically, the crystal furnace control method based on feedback regulation provided by the embodiments of the present invention can be applied to the above crystal furnace control system to achieve the same technical effects, which will not be elaborated here. Among them, the system is introduced relatively simply, and the same or similar content can be referred to in the method embodiments, and the specific details will not be elaborated here.

[0063] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

Claims

1. A crystal furnace control method based on feedback regulation, characterized in that, Including: Controlling the seed crystal chuck to perform a predetermined detection action, obtaining the rotational feedback force of the seed crystal chuck and an image of the seed crystal head area, wherein the predetermined detection action includes controlling the seed crystal chuck to rotate a predetermined number of turns while maintaining a predetermined height; Determining the stress interference uniformity based on the rotational feedback force, and analyzing the stress growth characteristics of the growing crystal based on the image of the seed crystal head area, the stress growth characteristics including the texture spacing and the maximum width of the growing crystal on the melt surface; Determining a stress interference characterization value based on the stress interference uniformity and the stress growth characteristics, and determining the stress interference category of the currently growing crystal, the stress interference category including a strong stress interference influence category and a weak stress interference influence category; If the stress interference category of the currently growing crystal is the strong stress interference influence category, determining target crystal growth parameters based on the stress interference characterization value and the initial crystal growth parameters; If the stress interference category of the currently growing crystal is the weak stress interference influence category, determining the initial crystal growth parameters as the target crystal growth parameters; Controlling the crystal furnace based on the target crystal growth parameters, monitoring the contour change of the growing crystal and the temperature change along the pulling direction after a target time period, and determining whether the crystal growth process meets a preset standard, wherein if not, re-determining the crystal growth parameters; Wherein, the crystal growth parameters include the pulling speed and the rotation speed.

2. The crystal furnace control method based on feedback regulation according to claim 1, wherein The determining of the stress interference uniformity includes: Constructing a feedback force time-domain curve based on the rotational feedback force, and identifying a specific rising segment of the feedback force time-domain curve; Determining the stress interference uniformity based on the smoothness of the specific rising segment of the feedback force time-domain curve.

3. The crystal furnace control method based on feedback regulation according to claim 1, wherein The determining of the stress interference characterization value includes: Determining a first characteristic value based on the comparison result between the stress interference uniformity and a preset uniformity; Determining a second characteristic value based on the texture spacing and the maximum width of the growing crystal on the melt surface; Determining the stress interference characterization value based on the first characteristic value and the second characteristic value.

4. The crystal furnace control method based on feedback regulation according to claim 1, characterized in that The determining of the stress interference category of the currently growing crystal includes: Determining the stress interference category of the currently growing crystal based on the comparison result between the stress interference characterization value and a preset characterization value; Wherein, if the stress interference characterization value is greater than the preset characterization value, determining the stress interference category of the currently growing crystal as the strong stress interference influence category; If the stress interference characterization value is less than or equal to the preset characterization value, determining the stress interference category of the currently growing crystal as the weak stress interference influence category.

5. The crystal furnace control method based on feedback regulation according to claim 1, characterized in that The determining of the target crystal growth parameters based on the stress interference characterization value and the initial crystal growth parameters includes: Determining a characterization adjustment parameter based on the comparison result between the stress interference characterization value and the preset characterization value; Determining the target crystal growth parameters based on the characterization adjustment parameter and the initial crystal growth parameters.

6. The crystal furnace control method based on feedback regulation according to claim 1, wherein, The determining of whether the crystal growth process meets the preset standard includes: Determining a contour characteristic value based on the contour change of the growing crystal after the target time period; Determining a temperature characteristic value based on the temperature change along the pulling direction; Determining whether the crystal growth process meets the preset standard based on the contour characteristic value and the temperature characteristic value.

7. The crystal furnace control method based on feedback regulation according to claim 6, characterized in that, The determining of the contour characteristic value includes: Determine a number of contour mutation regions based on the contour change of the grown crystal after the target time period; Determine the contour characteristic value based on the area and the maximum diameter length of each of the contour mutation regions.

8. The crystal furnace control method based on feedback regulation according to claim 6, wherein The determination of the temperature characteristic value includes: Construct a seed crystal-melt temperature gradient change curve based on the temperature change along the pulling direction; Determine a number of temperature key points based on the seed crystal-melt temperature gradient change curve; Determine the temperature characteristic value based on the comparison results of each of the temperature key points.

9. The crystal furnace control method based on feedback regulation according to claim 1, wherein The crystal growth process conforming to the preset standard means that the contour characteristic value is less than the preset contour characteristic value and the temperature characteristic value is less than the preset temperature characteristic value.

10. A crystal furnace control system, characterized in that, It includes: A pre-detection module, configured to control the seed crystal chuck to perform a predetermined detection action, and obtain the rotational feedback force of the seed crystal chuck and the image of the seed crystal head region, wherein the predetermined detection action includes controlling the seed crystal chuck to maintain a predetermined height and rotate a predetermined number of turns; A stress interference analysis module, configured to determine the stress interference uniformity based on the rotational feedback force, analyze the stress growth characteristics of the grown crystal based on the image of the seed crystal head region, and determine the stress interference characterization value based on the stress interference uniformity and the stress growth characteristics, and determine the stress interference category of the current grown crystal, wherein the stress growth characteristics include the texture spacing and the maximum width of the grown crystal on the melt surface, and the stress interference category includes a strong stress interference influence category and a weak stress interference influence category; A parameter determination module, configured to, if the stress interference category of the current grown crystal is the strong stress interference influence category, determine the target crystal growth parameters based on the stress interference characterization value and the initial crystal growth parameters; if the stress interference category of the current grown crystal is the weak stress interference influence category, determine the initial crystal growth parameters as the target crystal growth parameters; wherein the crystal growth parameters include the pulling speed and the rotational speed; A monitoring and analysis module, configured to grow crystals based on the target crystal growth parameters, monitor the contour change of the grown crystal after the target time period and the temperature change along the pulling direction, and determine whether the crystal growth process conforms to the preset standard, and if not, re-determine the crystal growth parameters.

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