Ingot growth control method

Abstract

The present invention discloses a method for controlling the growth of a crystal rod, comprising: detecting all growth edges of the crystal rod in the equal diameter growth stage; detecting the actual diameter of the crystal rod when all growth edges of the crystal rod are not broken; adjusting the growth process of the crystal rod according to the detected actual diameter of the crystal rod; wherein detecting the actual diameter of the crystal rod comprises: obtaining the arc length of the set arc segment corresponding to the growth edge at each position, calculating the diameter of the crystal rod at the corresponding growth edge position according to the arc length of the set arc segment; eliminating outlier data in the diameter data at the position where the growth edge is located, and obtaining the actual diameter of the crystal rod according to the remaining diameter data. According to the method for controlling the growth of a crystal rod in an embodiment of the present invention, the crystal rod diameter data obtained in this way is more accurate, thereby making it more accurate to adjust the growth process of the crystal rod.

Description

Technical Field

[0001] The invention relates to the field of single crystal production and manufacturing, and in particular to a crystal rod growth control method. Background Art

[0002] In the related art, the growth process of the crystal rod is usually adjusted according to the actual diameter of the crystal rod, so as to control the growth quality of the crystal rod. However, the data for detecting the actual diameter of the crystal rod in the related art is inaccurate, resulting in inaccurate adjustment of the crystal rod growth process according to the detected actual diameter of the crystal rod, which affects the stability of the process. In addition, the control system of the crystal rod growth (including the detection sensor and the computer control system) will cause incorrect control when receiving incorrect diameter information, which will cause the risk of wire breakage and quality abnormality, thereby resulting in poor quality of the grown crystal rod. Therefore, there is room for improvement. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the present invention is to propose a crystal rod growth control method, by taking multiple detection positions on the crystal rod to detect the diameter of the crystal rod, and the multiple detection positions include the positions where all the growth edges are located, by eliminating the outlier data in the diameter data at the position where the growth edge is located, and obtaining the actual diameter of the crystal rod based on the remaining diameter data, the crystal rod diameter data obtained in this way is more accurate, and based on this, the crystal rod growth process is adjusted in time, the stability of the growth process is maintained, and the risk of wire breakage and quality abnormalities occurring during the growth process is reduced.

[0004] According to an embodiment of the present invention, a method for controlling the growth of a crystal rod comprises: in a constant diameter growth stage, detecting all growth edges of the crystal rod; when all growth edges of the crystal rod are not broken, detecting the actual diameter of the crystal rod; and adjusting the growth process of the crystal rod according to the detected actual diameter of the crystal rod; wherein detecting the actual diameter of the crystal rod comprises: obtaining an arc segment corresponding to the growth edge at each position, the set arc segment being located on the circumference of the crystal rod, the growth edge being located within the set arc segment, and calculating the diameter of the crystal rod at the corresponding growth edge position according to the arc length of the set arc segment; eliminating outlier data in the diameter data at the position where the growth edge is located, and obtaining the actual diameter of the crystal rod according to the remaining diameter data.

[0005] According to the crystal rod growth control method of the embodiment of the present invention, a plurality of detection positions are taken on the crystal rod to detect the diameter of the crystal rod, and the plurality of detection positions include the positions where all the growth edges are located, and the outlier data in the diameter data at the positions where the growth edges are located are eliminated, and the actual diameter of the crystal rod is obtained according to the remaining diameter data, so as to serve as the basis for adjusting the crystal rod growth process. The crystal rod diameter data obtained in this way is more accurate, so that the growth process of the adjusted crystal rod is more accurate, and the risk of wire breakage and quality abnormality occurring during the growth process of the crystal rod is reduced, thereby making the quality of the grown crystal rod stable and of better quality.

[0006] According to some embodiments of the present invention, the width of the growth edge corresponding to the outlier data is detected, and the growth process of the crystal rod is adjusted according to the actual diameter of the crystal rod and the width of the growth edge corresponding to the outlier data.

[0007] According to some embodiments of the present invention, the growth process of the crystal rod is adjusted according to the actual diameter of the crystal rod and the width of the growth edge corresponding to the outlier data, including: first adjusting the growth process of the crystal rod according to the actual diameter of the crystal rod; and then further adjusting the growth process of the crystal rod according to the width of the growth edge corresponding to the outlier data.

[0008] According to some embodiments of the present invention, when the deviation between the actual diameter of the crystal rod and the set diameter value is greater than or equal to 3%, the growth process of the crystal rod is first adjusted according to the actual diameter of the crystal rod, and then the growth process of the crystal rod is further adjusted according to the width of the growth edge corresponding to the outlier data; or, when the deviation between the actual diameter of the crystal rod and the set diameter value is less than 3%, the growth process of the crystal rod is adjusted according to the width of the growth edge corresponding to the outlier data.

[0009] According to some embodiments of the present invention, the growth process of the crystal rod is adjusted according to the width of the growth edge corresponding to the outlier data, including: determining a width threshold according to the length of the equal-diameter section of the current crystal rod; and adjusting the growth process of the crystal rod according to the relationship between the width of the growth edge corresponding to the current outlier data and the width threshold.

[0010] According to some embodiments of the present invention, when it is detected that the width of the growth edge corresponding to the outlier data is greater than the width threshold, the solid-liquid interface temperature is increased;

[0011] When it is detected that the width of the growth edge corresponding to the outlier data is smaller than the width threshold, the solid-liquid interface temperature is reduced.

[0012] According to some embodiments of the present invention, determining a width threshold according to the length of the current equal-diameter segment of the crystal rod includes: dividing the equal-diameter segment of the target length into a first segment, a second segment, and a third segment arranged in sequence in a direction from the starting position of the equal-diameter segment to the end position of the equal-diameter segment, the length of the first segment is b1, the sum of the length of the first segment and the length of the second segment is b2, and the target length is b3, wherein (0, b1] is a first length interval, (b1, b2] is a second length interval, (b2, b3] is a third length interval, the first length interval corresponds to a first width threshold, the second length interval corresponds to a second width threshold, the third length interval corresponds to a third width threshold, and the first width threshold and the third width threshold are both smaller than the second width threshold;

[0013] The width threshold is determined according to a length interval in which an actual length of the equal-diameter section of the current crystal rod lies.

[0014] According to some embodiments of the present invention, the length of the first segment is 40% of the target length, and the corresponding first width threshold is L1, wherein 1㎜≤L1≤5㎜; the length of the second segment is 20% of the target length, and the corresponding second width threshold is L2, wherein 2㎜≤L2≤10㎜; the length of the third segment is 40% of the target length, and the corresponding third width threshold is L3, wherein 1㎜≤L3≤5㎜.

[0015] According to some embodiments of the present invention, the growth process of the crystal rod is adjusted according to the detected actual diameter of the crystal rod, which at least includes the following process steps: adjusting the pulling speed and adjusting the heater power; wherein, the adjusting the pulling speed includes: when the actual diameter of the crystal rod is greater than the diameter setting value, increasing the pulling speed; when the actual diameter of the crystal rod is less than the diameter setting value, reducing the pulling speed; the adjusting the heater power includes: when the actual diameter of the crystal rod is greater than the diameter setting value, increasing the heater power; when the actual diameter of the crystal rod is less than the diameter setting value, reducing the heater power.

[0016] According to some embodiments of the present invention, the central angle of the set arc segment is 10°-30°.

[0017] According to some embodiments of the present invention, the diameter of the crystal rod at the location of the growth edge is detected as D, and the calculation formula of D is: D = {X 2 +4Y 2} 1 / 2 , X is the arc length of the set arc segment, and Y is the distance between the chord corresponding to the set arc segment and the central axis of the crystal rod.

[0018] According to some embodiments of the present invention, if at least one growth edge of the crystal rod is broken, the growth of the crystal rod is stopped.

[0019] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0021] Figure 1 yes <111> Schematic diagram of the cross section of the crystal rod;

[0022] Figure 2 is a flow chart of a method for controlling crystal ingot growth according to an embodiment of the present invention;

[0023] Figure 3 yes Figure 2 Flow chart for detecting the actual diameter of the crystal rod;

[0024] Figure 4 The graph is a graph showing the change in diameter of the obtained crystal rod with the length of the crystal growth, in which the growth of the crystal rod is controlled using the crystal rod growth control method of Example 1 and Example 2 of the crystal rod growth control method according to an embodiment of the present invention and the crystal rod growth control method of Comparative Example 1 in the related art.

[0025] Reference numerals:

[0026] 20. Crystal rod; 10. Growth edge; 11. Wide surface growth edge; 12. Set arc segment. DETAILED DESCRIPTION

[0027] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0028] Reference below Figure 1-Figure 4 The growth control method of the crystal rod 20 according to an embodiment of the present invention is described. The crystal rod 20 in this embodiment may be a single crystal silicon crystal rod 20 .

[0029] The method for controlling the growth of the crystal rod 20 according to an embodiment of the present invention refers to Figure 2 ,include:

[0030] In the isodiameter growth stage, all growth edges 10 of the crystal rod 20 are detected;

[0031] When all the growth edges 10 of the crystal rod 20 are not broken, the actual diameter of the crystal rod 20 is detected;

[0032] The growth process of the crystal ingot 20 is adjusted according to the detected actual diameter of the crystal ingot 20 .

[0033] It should be noted that the disappearance of the ridgeline during the equal diameter stage of the crystal growth process is called wire breakage in the industry. When wire breakage occurs, the lattice arrangement inside the crystal rod 20 changes, resulting in the loss of the single crystal structure to polycrystalline, which cannot be restored.

[0034] When all the growth edges 10 of the crystal rod 20 are not broken, it can be understood that during the entire stage of equal diameter growth, all the growth edges 10 of the crystal rod 20 are distributed in the circumferential direction of the crystal rod 20 from beginning to end, and no growth edges 10 are broken or part of the growth edges 10 are broken. Crystal rods 20 with different crystal orientations have different numbers of growth edges 10, such as <111> The growth ridges 10 of the crystal rod 20 are three main crystal lines and are evenly distributed in the circumference of the crystal rod 20. <110> The growth ridges 10 of the crystal rod 20 are two main crystal lines and are evenly distributed in the circumference of the crystal rod 20. <100> The production edges of the crystal rod 20 are four main crystal lines which are evenly distributed in the circumferential direction of the crystal rod 20 .

[0035] If the growth edges 10 are distributed on the crystal rod 20 at the beginning of production, and the growth edges 10 disappear in the later stage of production, or the number of growth edges 10 detected on the crystal rod 20 does not match the crystal direction, it is a case of broken growth edges 10. When at least one growth edge 10 of the crystal rod 20 is detected to be broken, the growth of the crystal rod 20 is stopped, and the drawn crystal rod 20 is returned to the furnace to reduce the growth cost. In other words, when at least one growth edge 10 of the crystal rod 20 is broken, the crystal rod 20 has lost its single crystal structure and needs to be handled in time to reduce production losses.

[0036] In addition, in the actual growth process of the single crystal silicon rod, it is necessary not only to monitor in real time whether the crystal rod 20 is broken, but also to monitor in real time the diameter of the crystal rod 20. If the diameter is too large or too small, the subsequent rounding process of the crystal rod 20 is not suitable, and even the crystal rod 20 may be scrapped. Therefore, the inventor proposes to detect the arc length of the circumference of the crystal rod 20 corresponding to the growth edge 10 while detecting whether the growth edge 10 of the crystal rod 20 exists, so as to obtain the actual diameter of the crystal rod 20 in the equal diameter stage.

[0037] Among them, reference Figure 3 , detecting the actual diameter of the crystal rod 20, including:

[0038] S1: Obtain the arc length of the set arc segment 12 corresponding to the growth edge 10 at each position, the set arc segment 12 is located on the circumference of the crystal rod 20, and the growth edge 10 is located in the set arc segment 12, and calculate the diameter of the crystal rod 20 at the corresponding position of the growth edge 10 according to the arc length of the set arc segment 12;

[0039] For specific diameter calculation, please refer to Figure 1 , such as Figure 1 As shown in the figure, X is the arc length of the set arc segment 12, and Y is the distance between the chord corresponding to the set arc segment 12 and the central axis of the crystal rod 20. The diameter of the detected crystal rod 20 at the location of the growth edge 10 is D, and the calculation formula of D is: D = {X 2 +4Y 2} 1 / 2 By using D = {X 2 +4Y 2} 1 / 2 To calculate the diameters at the locations where all growth edges 10 are located, the diameter data at the locations where all growth edges 10 are located can be obtained.

[0040] It can be understood that the detection mechanism, such as a CCD camera, first captures the growth edge 10 on the crystal rod 20, and calculates the diameter of the crystal rod 20 at the growth edge 10 based on the arc length of the circumference of the crystal rod 20 at the location of the growth edge 10 and the distance between the arc length and the central axis of the crystal rod 20. In the process of detecting the diameter of the crystal rod 20, multiple detection positions are taken, and the multiple detection positions include the positions where all the growth edges 10 are located. <111> The growth edges 10 of the crystal rod 20 are three main crystal lines, so the detection mechanism detects the diameter of the crystal rod 20 at the location of the three growth edges 10. If the rotation period of the crystal rod 20 is T, the detection is performed once every T / 3 interval, and the diameter of the crystal rod 20 corresponding to different growth edges 10 can be detected in real time.

[0041] S2: Eliminate outlier data from the diameter data at the location of the growth edge 10, and obtain the actual diameter of the crystal rod 20 based on the remaining diameter data.

[0042] Specifically, according to step S1, the diameter of the crystal rod 20 can be obtained according to the arc length of the set arc segment 12 corresponding to the different growth edges 10 detected in real time. In order to obtain a more accurate actual diameter of the crystal rod 20, it is necessary to remove outlier data in the diameter data. Outlier data refers to data points in the data set that deviate significantly from other data, and can generally be determined by standard deviation, variance, etc. For example, the data with the largest standard deviation can be used as outlier data. After removing the outlier data, the actual diameter of the crystal rod 20 can be obtained based on the average value of the remaining diameter data. In the equal-diameter growth stage, the above steps can be used to detect the actual diameter of the single crystal silicon rod in real time. At this time, the control system of the single crystal furnace adjusts the growth process in time according to the actual diameter of the crystal rod 20 detected in real time to stabilize production.

[0043] In the above two steps of detecting the actual diameter of the crystal rod 20, during the growth of the crystal rod 20, since the crystal rod 20 grows in a certain growth direction, growth edges 10 will appear on the crystal rod 20. For example, in the equal diameter stage, the crystal direction <111> Produce 3 growth edges 10, crystal direction <110> Generate 2 growth edges 10, crystal direction <100> Four growth edges 10 are generated. During the growth of the crystal ingot 20, since the growth edges 10 are easy to capture, such as by using a CCD camera to capture the growth edges 10, by capturing the arc length of the set arc segment 12 at the location of the growth edges 10, and according to the arc length of the set arc segment 12 at which the growth edges 10 are located, the diameter of the crystal ingot 20 at the corresponding location of the growth edges 10 is calculated, which facilitates the detection and tracking of changes in the actual diameter of the crystal ingot 20.

[0044] It should be noted that the arc length of the set arc segment 12 at the location of the growth edge 10 is the length of the curve near the location of the growth edge 10 (refer to Figure 1 The width of the growth ridge 10 is the straight-line distance between the two end points of the circle where the growth ridge 10 and the crystal rod 20 intersect (refer to Figure 1 The width a of the growth edge 10 in the figure, the width of the growth edge 10 and the arc length of the set arc segment 12 at the location of the growth edge 10 are different.

[0045] In fact, since there is a certain difference between the curve of the position where the growth ridge 10 on the crystal rod 20 is located and the curve of the circle where the crystal rod 20 is located, when the width of the growth ridge 10 increases, the difference between the curve of the position where the growth ridge 10 with increased width is located and the curve of the circle where the crystal rod 20 is located will increase, and relative to other growth ridges 10, the diameter data of the crystal rod 20 detected at the position where the significantly widened growth ridge 10 is located will be greatly different from the actual diameter of the crystal rod 20. For example, the curve of the position where the significantly widened growth ridge 10 is located may be close to a straight line, and the curve at the detected position may be far from the curve of the actual circle, and the measured diameter data is not accurate enough. On the contrary, if the width of the growth ridge 10 becomes narrower, the growth ridge 10 may be broken and the single crystal structure may be lost.

[0046] Therefore, the present invention realizes that there may be outlier data in the diameter data at the location of the growth edge 10 of the crystal rod 20. In the process of calculating the actual diameter of the crystal rod 20, the present invention removes the outlier data in the diameter data at the location of the growth edge 10. By removing the outlier data, the influence of the outlier data at the location of the growth edge 10 on the actual diameter of the obtained crystal rod 20 can be reduced, so that the detected diameter data of the crystal rod 20 is more accurate. In addition, in the process of detecting the actual diameter of the crystal rod 20, multiple detection positions are taken, and the multiple detection positions include the locations of all the growth edges 10. By removing the outlier data in the diameter data at the location of the growth edge 10, and obtaining the actual diameter of the crystal rod 20 based on the remaining diameter data, the obtained diameter data of the crystal rod 20 can be made more accurate.

[0047] For the convenience of description, the production edge corresponding to the outlier data is named the wide surface growth edge 11. When calculating the actual diameter of the crystal rod 20, the diameter of the crystal rod 20 corresponding to the wide surface growth edge 11 is eliminated, and the actual diameter of the crystal rod 20 is calculated based on the diameter data corresponding to the remaining growth edges 10 at other positions.

[0048] like Figure 1 In the example, the crystal rod 20 is arranged in the crystal direction <111> In the growth direction, three growth edges 10 will appear on the crystal rod 20 in the equal diameter stage, among which the growth edge 10 corresponding to the outlier data is the wide surface growth edge 11.

[0049] In summary, the control method of the present invention adjusts the growth process conditions of the crystal rod 20 in real time according to the actual diameter of the crystal rod 20 obtained in real time. Since the actual diameter obtained is more accurate, the stability of the growth process is guaranteed and the quality of the single crystal rod 20 is improved.

[0050] In the growth process of single crystal silicon rods, temperature is a crucial factor, especially the temperature of the solid-liquid interface, but there is currently no way to directly measure and monitor this temperature. Low temperature may cause redistribution of stress inside the crystal. Due to the particularity of the lattice structure within the crystal, growth edges 10 in different directions correspond to different stress states. When the temperature drops, the crystal may release or redistribute stress by adjusting its internal structure, which causes the growth edges 10 in certain directions to widen to adapt to the new stress state. Based on the general speculation of crystal growth, when the temperature becomes lower, only one growth edge 10 will widen (called the wide-surface growth edge 10). The inventors further discovered that the temperature can be monitored by detecting the width of the wide-surface growth edge 10, thereby timely adjusting the growth process of the single crystal silicon rod.

[0051] In some embodiments, the growth control method provided by the present invention comprises:

[0052] First, the width of the growth edge 10 corresponding to the outlier data is detected.

[0053] Thirdly, the growth process of the single crystal silicon rod is adjusted according to the actual diameter of the crystal rod 20 and the width of the growth edge line 10 corresponding to the outlier data.

[0054] Specifically, the width of the growth ridge 10 corresponding to the outlier data is detected, and the temperature is monitored to see if it is appropriate based on the width of the wide growth ridge 10. If the temperature is not appropriate, the temperature can be adjusted by adjusting the growth process of the crystal rod 20, such as the heater power, the distance between the guide tube and the solid-liquid interface, and the position of the heater and the crucible, and then the width of the wide growth ridge 10 is adjusted, so that the width of the wide growth ridge 10 matches the appropriate temperature. Based on the relationship between the actual diameter of the crystal rod 20 and the threshold diameter detected in real time, the growth process of the crystal rod 20, such as the pulling speed and the heater power, is adjusted in time. In short, based on the actual diameter of the real-time crystal rod 20 and the width of the wide growth ridge 10, the growth process of the crystal rod 20 is adjusted in time, the diameter of the crystal rod 20 and the width of the wide growth ridge 10 are controlled, the crystallization rate is improved, and the process is maintained stable.

[0055] According to some embodiments of the present invention, the growth process of the crystal ingot 20 is adjusted according to the actual diameter of the crystal ingot 20 and the width of the growth edge line 10 corresponding to the outlier data, including:

[0056] First, the growth process of the crystal rod 20 is adjusted according to the actual diameter of the crystal rod 20;

[0057] The growth process of the crystal rod 20 is further adjusted according to the width of the growth edge line 10 corresponding to the outlier data.

[0058] In a specific embodiment, a crystal rod 20 of 310±5 mm is pulled by the growth control method of the present invention. In the equal diameter growth stage, in order to ensure that the actual diameter of the pulled crystal rod 20 is closer to the preset diameter of 310±5 mm, the diameter of the crystal rod 20 is first calculated based on the arc length of the circumference of the crystal rod 20 at the position of the growth edge 10 detected in real time, and the actual diameter of the crystal rod 20 is obtained based on the remaining diameter data after removing the outlier data. The control system can accurately adjust the growth process in real time based on the actual diameter; then, the temperature at the solid-liquid interface is monitored based on the width of the growth edge 10 corresponding to the outlier data, that is, the width of the wide growth edge 10. If the temperature is too cold, the wide growth edge 10 will be too wide, and the growth process of the crystal rod 20 is fine-tuned to increase the temperature. If the temperature is too hot, the wide growth edge 10 will be too narrow, or even broken, and the growth process of the crystal rod 20 is fine-tuned accordingly to reduce the temperature.

[0059] Therefore, the above-mentioned growth control method of the present invention adjusts the growth process parameters of the crystal rod 20 in real time according to the actual diameter of the crystal rod 20 obtained in real time, and then monitors the temperature at the solid-liquid interface in real time through the width of the wide surface growth ridge 10 under the premise of ensuring that the actual diameter of the crystal rod 20 is close to the preset diameter, and then further fine-tunes the production process parameters to prevent the temperature from overheating and causing the wire to break, or the temperature from being too cold so that the width of the wide surface growth ridge 10 is too wide and cannot be rounded. The growth process of the crystal rod 20 is essentially a cyclic process of continuously adjusting the production process in real time according to the actual diameter of the crystal rod 20 obtained in real time, and then monitoring the temperature at the solid-liquid interface according to the width of the wide surface growth ridge 10, and fine-tuning the production process in real time.

[0060] Among them, adjusting the growth process of the crystal rod 20 according to the width of the growth edge 10 corresponding to the outlier data may include: monitoring the temperature of the solid-liquid interface according to the width of the growth edge 10 corresponding to the outlier data. The formation of the growth edge 10 on the crystal rod 20 is closely related to its growth process. In the growth process of the crystal rod 20, temperature is a crucial factor. Temperature not only affects the diffusion rate of silicon atoms, but also affects the stability and growth direction of the crystal structure. If only the growth edge 10 in a certain direction is significantly affected by the temperature reduction, then this growth edge 10 may become wider due to the change in growth rate. While controlling the growth process of the crystal rod 20 according to the actual diameter of the crystal rod 20, monitoring the temperature of the solid-liquid interface according to the width of the growth edge 10 corresponding to the outlier data can better avoid the low temperature of the solid-liquid interface causing the growth edge 10 to become significantly wider and affect the growth quality of the crystal rod 20.

[0061] According to some embodiments of the present invention, when the deviation between the actual diameter of the crystal rod 20 and the set diameter value is greater than or equal to 3%, the growth process of the crystal rod 20 is first adjusted according to the actual diameter of the crystal rod 20, and then the growth process of the crystal rod 20 is further adjusted according to the width of the growth edge 10 corresponding to the outlier data. When the deviation between the actual diameter of the crystal rod 20 and the set diameter value is greater than or equal to 3%, it means that the actual diameter of the crystal rod 20 has a large deviation from the set diameter value, and the growth process of the crystal rod 20 must be adjusted according to the actual diameter of the crystal rod 20, and then the growth process of the crystal rod 20 must be further adjusted according to the width of the growth edge 10, so as to achieve precise adjustment of the growth process of the crystal rod 20, stabilize the production of the crystal rod 20, and make the quality of the final output crystal rod 20 better.

[0062] According to some embodiments of the present invention, when the deviation between the actual diameter of the crystal rod 20 and the set diameter value is less than 3%, the growth process of the crystal rod 20 is adjusted according to the width of the growth edge line 10 corresponding to the outlier data. When the deviation between the actual diameter of the crystal rod 20 and the set diameter value is less than 3%, it means that the deviation between the actual diameter of the crystal rod 20 and the set diameter value is small, and the growth process of the crystal rod 20 can be fine-tuned according to the width of the growth edge line 10 corresponding to the outlier data.

[0063] According to some embodiments of the present invention, adjusting the growth process of the crystal rod 20 according to the width of the growth edge line 10 corresponding to the outlier data includes:

[0064] Determine a width threshold according to the length of the equal-diameter section of the current crystal ingot 20;

[0065] The growth process of the crystal rod 20 is adjusted according to the relationship between the width of the growth edge line 10 corresponding to the current outlier data and the width threshold.

[0066] The above scheme can be understood as that when the crystal rod 20 is at different lengths in the equal diameter growth stage, the width of the growth edge 10 changes relatively regularly with the length of the equal diameter section. By determining the width threshold according to the length of the equal diameter section of the current crystal rod 20, that is, the setting of the width threshold can be performed according to the different length positions of the crystal rod 20 in the equal diameter growth stage, so that the crystal rod 20 can correspond to a more matching width threshold at different lengths of the equal diameter section. According to the relationship between the width of the growth edge 10 corresponding to the current outlier data and the width threshold, the growth process of the adjusted crystal rod 20 is more accurate and more matched, which is more conducive to better controlling the growth process of the crystal rod 20 within the length range of different equal diameter sections, so that the growth quality of the crystal rod 20 in different equal diameter sections can be better controlled.

[0067] According to some embodiments of the present invention, a width threshold is determined based on the length of the equal-diameter section of the current crystal rod 20, including: in the direction from the starting position of the equal-diameter section to the end position of the equal-diameter section, the equal-diameter section of the target length is divided into a first section, a second section and a third section arranged in sequence, the length of the first section is b1, the sum of the length of the first section and the length of the second section is b2, the target length is b3, wherein (0, b1] is a first length interval, (b1, b2] is a second length interval, (b2, b3] is a third length interval, the first length interval corresponds to a first width threshold, the second length interval corresponds to a second width threshold, the third length interval corresponds to a third width threshold, and the first width threshold and the third width threshold are both less than the second width threshold; the width threshold is determined based on the length interval in which the actual length of the equal-diameter section of the current crystal rod 20 is located.

[0068] Since the width of the growth edge 10 increases relatively regularly as the length of the equal-diameter section of the crystal rod 20 increases from narrow to wide to narrow, by making the first width threshold and the third width threshold both smaller than the second width threshold, the setting of the width threshold can be made more accurate, and the growth process of the crystal rod 20 adjusted according to the relationship between the width of the growth edge 10 corresponding to the current outlier data and the width threshold is more precise, the growth process is more stable, and the quality of the produced crystal rod 20 is more stable.

[0069] According to some embodiments of the present invention, the length of the first section is 40% of the target length, and the corresponding first width threshold is L1, where 1㎜≤L1≤5㎜; the length of the second section is 20% of the target length, and the corresponding second width threshold is L2, where 2㎜≤L2≤10㎜; the length of the third section is 40% of the target length, and the corresponding third width threshold is L3, where 1㎜≤L3≤5㎜. According to the growth characteristics of different sections of the crystal rod 20 in the equal diameter stage, the lengths of different sections are determined so that different sections match more appropriate width thresholds, so that the growth of different sections of the crystal rod 20 in the equal diameter stage can be better controlled, so that the diameter stability of the crystal rod 20 is better overall during the entire equal diameter growth stage, and the overall growth quality of the crystal rod 20 is better.

[0070] It can be understood that the first section is within 40% of the target length, and the corresponding first width threshold is L1; the second section is within 20% of the target length, and the corresponding second width threshold is L2; ​​the third section is within 40% of the target length, and the corresponding third width threshold is L3. According to some embodiments of the present invention, when the width of the growth edge 10 corresponding to the detected outlier data is greater than the width threshold, the solid-liquid interface temperature is increased; when the width of the growth edge 10 corresponding to the detected outlier data is less than the width threshold, the solid-liquid interface temperature is reduced. When the width of the growth edge 10 corresponding to the detected outlier data is greater than the width threshold, the temperature of the solid-liquid interface is increased, so that the temperature of the growth environment of the crystal rod 20 is increased, and the actual width of the growth edge 10 is reduced, so that the actual width of the growth edge 10 is close to the width threshold; when the width of the growth edge 10 corresponding to the detected outlier data is less than the width threshold, the temperature of the solid-liquid interface is reduced, so that the temperature of the growth environment of the crystal rod 20 is reduced, and the actual width of the growth edge 10 is increased, so that the actual width of the growth edge 10 is close to the width threshold.

[0071] In a specific embodiment, in order to timely adjust the width of the growth edge 10 corresponding to the outlier data to the corresponding width threshold, the heater power may be adjusted as follows:

[0072] When the ridge width W is greater than the threshold value L, the adjustment is as follows: the width growth ridge 10 of the first section is detected as W1, when 5%<(W1-L1) / L1<20%, ​​the heater power is increased by 1kw, when 20%≤(W1-L1) / L1<50%, the heater power is increased by 3kw, when 50%≤(W1-L1) / L1, the heater power is increased by 5kw; the width growth ridge 10 of the second section is detected as W2, when 5%<(W2-L2) / L2<10%, the heater power is increased 1kw, when 10%≤(W2-L2) / L2<30%, the heater power increases by 3kw, when 30%≤(W2-L2) / L2, the heater power increases by 5kw; the width growth edge 10 of the third section is detected as W3, when 5%<(W3-L3) / L3<15%, the heater power increases by 1kw, when 15%≤(W3-L3) / L3<40%, the heater power increases by 3kw, when 40%≤(W3-L3) / L3, the heater power increases by 5kw.

[0073] When the ridge width W is less than the threshold value L, the adjustment is as follows: the width growth ridge 10 of the first section is detected as W1, when -20%<(W1-L1) / L1<-5%, the heater power is reduced by 1kw, when -50%<(W1-L1) / L1≤-20%, the heater power is reduced by 3kw, when (W1-L1) / L1≤-50%, the heater power is reduced by 5kw; the width growth ridge 10 of the second section is detected as W2, when -10%<(W2-L2) / L2<-5%, the heater power is reduced 1kw, when -30%<(W2-L2) / L2≤-10%, the heater power is reduced by 3kw, when (W2-L2) / L2≤-30%, the heater power is reduced by 5kw; the width growth edge 10 of the third section is detected as W3, when -15%<(W3-L3) / L3<-5%, the heater power is reduced by 1kw, when -40%<(W3-L3) / L3≤-15%, the heater power is reduced by 3kw, when (W3-L3) / L3≤-40%, the heater power is increased by 5kw.

[0074] According to some embodiments of the present invention, adjusting the growth process of the crystal rod 20 according to the detected actual diameter of the crystal rod 20 includes at least the following process steps:

[0075] Adjust the pulling speed and heater power;

[0076] The adjusting of the pulling speed includes: when the actual diameter of the crystal rod 20 is greater than the diameter setting value, increasing the pulling speed; when the actual diameter of the crystal rod 20 is less than the diameter setting value, reducing the pulling speed.

[0077] When it is detected that the actual diameter of the crystal rod 20 is greater than the set diameter value, the pulling speed is increased. At this time, the crystal rod 20 is prevented from growing radially at the solid-liquid interface, which can reduce the actual diameter of the crystal rod 20, thereby making the actual diameter of the crystal rod 20 closer to the set diameter value; when it is detected that the actual diameter of the crystal rod 20 is less than the set diameter value, the pulling speed is reduced. At this time, the crystal rod 20 grows radially at the solid-liquid interface, which can increase the actual diameter of the crystal rod 20, thereby making the actual diameter of the crystal rod 20 closer to the set diameter value.

[0078] The heater power is adjusted, including: when the actual diameter of the crystal rod 20 is greater than the diameter setting value, the heater power is increased; when the actual diameter of the crystal rod 20 is less than the diameter setting value, the heater power is reduced.

[0079] When it is detected that the actual diameter of the crystal rod 20 is greater than the diameter setting value, increasing the heater power can increase the temperature of the growth environment of the crystal rod 20, reduce the actual diameter of the crystal rod 20, and thus bring the actual diameter of the crystal rod 20 closer to the diameter setting value; when it is detected that the actual diameter of the crystal rod 20 is less than the diameter setting value, reducing the heater power can reduce the temperature of the growth environment of the crystal rod 20, increase the actual diameter of the crystal rod 20, and thus bring the actual diameter of the crystal rod 20 closer to the diameter setting value.

[0080] According to some embodiments of the present invention, the center angle of the arc segment 12 is set to α, and the value range of α is 10°-30°. By setting the value range of α to 10°-30°, such as α can be 10°, 13°, 15°, 17°, 20°, 22°, 25°, 28°, 30°, the diameter of the crystal rod 20 at the corresponding position of the growth edge 10 calculated according to the arc length of the set arc segment 12 can be made more accurate. Because the set arc segment 12 where the growth edge 10 is located may jump during the production process, in order to ensure that the measured arc length of the set arc segment 12 is more accurate, the center angle of the set arc segment 12 is selected to be at least 10°. If the center angle α of the set arc segment 12 is greater than 30°, the error of the detected arc length of the set arc segment 12 will be larger.

[0081] According to some embodiments of the present invention, a PID control module is used to monitor the width of the growing ridge 10 and control the solid-liquid interface temperature. The PID control module has the advantages of simple structure, good stability, reliable operation and convenient adjustment. The control of the PID control module includes three parameters: kP (proportional parameter), kD (differential parameter) and kI (integral parameter). For example, the preset diameter and the preset ridge width can be input into the PID control module, and the actual diameter of the crystal rod 20 and the width of the growing ridge 10 can be detected in real time. According to the relationship between the actual diameter of the crystal rod 20 and the diameter setting value and the relationship between the width of the growing ridge 10 and the width threshold, the pulling speed of the crystal rod 20 and the heating power of the heater are controlled by the PID control module to achieve the purpose of adjusting the diameter and the solid-liquid interface temperature.

[0082] kP (proportional parameter): When there is a gap between the quantity to be controlled (such as solid-liquid interface temperature) and the target value, adjust the regulation intensity according to the size of the gap.

[0083] kD (differential parameter): It mainly plays a role similar to "damping", making the "change rate" of the controlled physical quantity approach 0.

[0084] kI (integral parameter): It is used to reduce the error in static conditions and make the quantity to be controlled (such as solid-liquid interface temperature) as close to the target value as possible.

[0085] By using the PID control module to adjust the temperature of the solid-liquid interface, the temperature of the solid-liquid interface can be adjusted more accurately and effectively, and the diameter stability of the crystal rod 20 finally produced can be made higher; and the adjustment process can also be made simpler.

[0086] The growth control method of the crystal rod 20 according to the embodiment of the present invention is further described below in combination with some embodiments and comparative examples.

[0087] Embodiment 1: The growth of the crystal rod 20 is controlled by using the growth control method of the crystal rod 20 in the embodiment of the present invention.

[0088] Embodiment 2: The growth control method of the crystal rod 20 in the embodiment of the present invention is used to control the growth of the crystal rod 20. The difference from Embodiment 1 is that the relevant parameters of the PID control module are adjusted.

[0089] Comparative Example: A method for controlling the growth of the crystal rod 20 in the related art is used to control the growth of the crystal rod 20. For example, a method for controlling the growth of the crystal rod 20 by using the pulling speed. The control system in the growth control method used in the comparative example is used to control the process parameters, and generally adopts closed-loop feedback control. The diameter of the crystal rod 20 is read by a detection device such as a CCD camera, and the read diameter value is sent to the control system. In order to control the diameter, the control system will output a signal to adjust the pulling speed and temperature.

[0090] Table 1

[0091]

[0092] Referring to Table 1, Table 1 is a table showing the changes in the diameter of the crystal rod 20 and the width of the growth edge line 1011 along with the length of the equal diameter segment obtained by controlling the growth of the crystal rod 20 using the crystal rod 20 growth control methods of Example 1, Example 2 and Comparative Example 1 respectively.

[0093] refer to Figure 4 , Figure 4 The growth of the crystal rod 20 is controlled by using the growth control methods of the crystal rod 20 of Example 1, Example 2 and Comparative Example 1, respectively, to obtain a graph showing the change in the diameter of the crystal rod 20 with the length of the equal diameter section. The diameters of the crystal rods 20 of Examples 1 and 2 are more stable and closer to the set diameter value than those of the comparative example, indicating that the growth control method of the crystal rod 20 in the embodiment of the present invention can make the detected diameter data of the crystal rod 20 more accurate and the diameter of the crystal rod 20 more stable.

[0094] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0095] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for controlling crystal rod growth, characterized in that: include: In the isodiameter growth stage, detecting all growth edges of the crystal rod; When all growth edges of the crystal rod are not broken, detecting the actual diameter of the crystal rod; adjusting the growth process of the crystal ingot according to detecting the actual diameter of the crystal ingot; Wherein, detecting the actual diameter of the crystal rod includes: Obtaining a set arc segment corresponding to the growth edge line at each position, wherein the set arc segment is located on the circumference of the crystal rod, and the growth edge line is located within the set arc segment, and calculating the diameter of the crystal rod at the corresponding position of the growth edge line according to the arc length of the set arc segment; Outlier data in the diameter data at the location of the growth edge are eliminated, and the actual diameter of the crystal rod is obtained based on the remaining diameter data.

2. The method for controlling the growth of a crystal rod according to claim 1, characterized in that: The width of the growth edge corresponding to the outlier data is detected, and the growth process of the crystal ingot is adjusted according to the actual diameter of the crystal ingot and the width of the growth edge corresponding to the outlier data.

3. The method for controlling the growth of a crystal rod according to claim 2, characterized in that: According to the actual diameter of the crystal rod and the width of the growth edge corresponding to the outlier data, the growth process of the crystal rod is adjusted, including: First, adjusting the growth process of the crystal rod according to the actual diameter of the crystal rod; The growth process of the crystal rod is further adjusted according to the width of the growth edge corresponding to the outlier data.

4. The method for controlling the growth of a crystal rod according to claim 3, characterized in that: When the deviation between the actual diameter of the crystal ingot and the set diameter value is greater than or equal to 3%, firstly adjusting the growth process of the crystal ingot according to the actual diameter of the crystal ingot, and then further adjusting the growth process of the crystal ingot according to the width of the growth ridge corresponding to the outlier data; Alternatively, when the deviation between the actual diameter of the crystal rod and the set diameter value is less than 3%, the growth process of the crystal rod is adjusted according to the width of the growth edge corresponding to the outlier data.

5. The method for controlling the growth of a crystal rod according to any one of claims 2 to 4, characterized in that: Adjusting the growth process of the crystal rod according to the width of the growth edge corresponding to the outlier data includes: Determining a width threshold according to the length of the equal-diameter section of the current crystal rod; The growth process of the crystal rod is adjusted according to the relationship between the width of the growth edge corresponding to the current outlier data and the width threshold.

6. The method for controlling the growth of a crystal rod according to claim 5, characterized in that: When the width of the growth edge corresponding to the outlier data is detected to be greater than the width threshold, increasing the solid-liquid interface temperature; When it is detected that the width of the growth edge corresponding to the outlier data is smaller than the width threshold, the solid-liquid interface temperature is reduced.

7. The method for controlling the growth of a crystal rod according to claim 5, characterized in that: Determining a width threshold according to the length of the equal-diameter section of the current crystal ingot includes: In the direction from the starting position of the equal-diameter segment to the end position of the equal-diameter segment, the equal-diameter segment of the target length is divided into a first segment, a second segment and a third segment arranged in sequence, the length of the first segment is b1, the sum of the length of the first segment and the length of the second segment is b2, and the target length is b3, wherein (0, b1] is a first length interval, (b1, b2] is a second length interval, (b2, b3] is a third length interval, the first length interval corresponds to a first width threshold, the second length interval corresponds to a second width threshold, the third length interval corresponds to a third width threshold, and the first width threshold and the third width threshold are both smaller than the second width threshold; The width threshold is determined according to a length interval in which an actual length of the equal-diameter section of the current crystal rod lies.

8. The method for controlling the growth of a crystal rod according to claim 7, characterized in that: The length of the first section is 40% of the target length, and the corresponding first width threshold is L1, where 1 mm≤L1≤5 mm; The length of the second section is 20% of the target length, and the corresponding second width threshold is L2, where 2㎜≤L2≤10㎜; The length of the third section is 40% of the target length, and the corresponding third width threshold is L3, wherein 1㎜≤L3≤5㎜.

9. The method for controlling the growth of a crystal rod according to claim 1, characterized in that: According to the detected actual diameter of the crystal rod, adjusting the growth process of the crystal rod at least includes the following process steps: adjusting the pulling speed and adjusting the heater power; Wherein, adjusting the pulling speed includes: When the actual diameter of the crystal rod is greater than the set diameter value, the pulling speed is increased; When the actual diameter of the crystal rod is smaller than the set diameter value, the pulling speed is reduced; The step of adjusting the heater power comprises: When the actual diameter of the crystal rod is greater than the set diameter value, the heater power is increased; When the actual diameter of the crystal rod is smaller than the set diameter value, the heater power is reduced.

10. The method for controlling the growth of a crystal rod according to claim 1, characterized in that: The central angle of the set arc segment is 10°-30°.

11. The method for controlling the growth of a crystal rod according to claim 1, characterized in that: The diameter of the crystal rod at the location of the growth edge is detected as D, and the calculation formula of D is: D = {X 2 +4Y 2 } 1 / 2 , X is the arc length of the set arc segment, and Y is the distance between the chord corresponding to the set arc segment and the central axis of the crystal rod.

12. The method for controlling the growth of a crystal rod according to claim 1, characterized in that: If at least one growth edge of the crystal rod is broken, the growth of the crystal rod is stopped.

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