Method for controlling growth of single crystal silicon and device for controlling growth of single crystal silicon

Abstract

The invention provides a growth control method of monocrystalline silicon and a growth control device of monocrystalline silicon. The growth control method of the monocrystalline silicon comprises the following steps: in a pulling process of a monocrystalline silicon rod, acquiring a real-time pulling speed v of the monocrystalline silicon rod, and acquiring a real-time temperature gradient G at a solid-liquid growth interface of the monocrystalline silicon rod; and the real-time ratio of the real-time pulling speed v to the real-time temperature gradient G is calculated. And comparing the real-time ratio with a preset ratio range, and adjusting the real-time pulling speed v and / or the real-time temperature gradient G according to a comparison result, so that the real-time ratio is within the preset ratio range. According to the growth control method of the monocrystalline silicon, in-situ feedback control of the monocrystalline silicon in the growth process is realized, and the method is suitable for various different single crystal furnaces and crystal pulling processes. And exploration time and material consumption can be saved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a growth control method and a growth control device for single crystal silicon. Background Art

[0002] Single crystal silicon is a semiconductor material commonly used in integrated circuits and solar cells. Currently known methods for manufacturing single crystal silicon can generally be divided into the Czochralski method, the zone melting method and the epitaxial method. Among them, the Czochralski method can produce single crystal silicon of larger size and has become a commonly used method for producing single crystal silicon. The principle of the Czochralski method is: inserting a seed crystal into the molten silicon, and the seed crystal absorbs the molten silicon to form a new crystal layer after contacting the molten silicon. At the same time, the seed crystal is pulled upward from the molten silicon and rotated around its own axis to ensure that the silicon atoms in the molten silicon are evenly deposited on the seed crystal, thereby forming a large-sized single crystal silicon rod with the same crystal orientation.

[0003] Single crystal defects are an important factor affecting the quality of single crystal silicon. In the process of manufacturing single crystal silicon by the Czochralski method, the growth rate of the crystal and the axial temperature gradient near the solid-liquid interface are important factors affecting the amount of defects. The growth rate of the crystal can be controlled by the pulling speed of the single crystal silicon. During the crystal pulling process, as the single crystal continues to grow, the axial temperature gradient will gradually decrease. This is mainly because as the crystal grows, the length of the crystal increases, the volume increases, the heat dissipation resistance near the solid-liquid interface increases, and the axial temperature gradient inside the crystal decreases. In order to obtain single crystal silicon products with fewer single crystal defects, traditional technologies usually rely on experience or use professional software simulation to iterate and form a set of suitable process parameters. However, this method requires re-exploring suitable process parameters for new structures and new processes every time, which has a limited scope of application and is time-consuming and labor-intensive. Summary of the invention

[0004] Based on this, it is necessary to provide a growth control method and a growth control device for single crystal silicon that can improve the quality of single crystal silicon.

[0005] According to some embodiments of the present disclosure, a method for controlling growth of single crystal silicon is provided, which comprises the following steps:

[0006] During the pulling process of the single crystal silicon rod, obtaining the real-time pulling speed v of the single crystal silicon rod and obtaining the real-time temperature gradient G at the solid-liquid growth interface of the single crystal silicon rod;

[0007] Calculating a real-time ratio of the real-time pulling speed v to the real-time temperature gradient G; and,

[0008] The real-time ratio is compared with a preset ratio range, and the real-time pulling speed v and / or the real-time temperature gradient G are adjusted according to the comparison result so that the real-time ratio is within the preset ratio range.

[0009] In some embodiments of the present disclosure, a method for obtaining the real-time temperature gradient G at the solid-liquid growth interface of the single crystal silicon rod includes:

[0010] Simultaneously monitoring the temperatures of a plurality of temperature measuring points sequentially distributed in the vertical direction in the molten silicon;

[0011] The real-time temperature gradient G is calculated based on the temperatures of the multiple temperature measuring points and the distances between the multiple temperature measuring points.

[0012] In some embodiments of the present disclosure, among the multiple temperature measuring points, the distance between the temperature measuring point closest to the solid-liquid growth interface and the solid-liquid growth interface is ≤20 mm, and the distance between the temperature measuring point farthest from the solid-liquid growth interface and the solid-liquid growth interface is ≤150 mm.

[0013] In some embodiments of the present disclosure, the distance between any two adjacent temperature measurement points is 10 mm to 50 mm.

[0014] In some embodiments of the present disclosure, there are three temperature measurement points, which are respectively recorded as point A, point B and point C. Point B is located between point A and point C. The temperatures measured at point A, point B and point C are respectively recorded as T A 、T B 、T C , the distance between point A and point B is recorded as D AB , the distance between point B and point C is recorded as D BC ;

[0015] The real-time temperature gradient G is calculated using the following formula:

[0016]

[0017] In some embodiments of the present disclosure, the preset ratio range is 0.135 mm 2 / (min·K)~0.140mm 2 / (min·K).

[0018] In some embodiments of the present disclosure, in the step of adjusting the real-time pulling speed v and / or adjusting the real-time temperature gradient G according to the comparison result, the real-time pulling speed v is kept unchanged, and only the real-time temperature gradient G is adjusted. The step of adjusting the real-time temperature gradient G includes:

[0019] When the real-time ratio is greater than a preset ratio range, increasing the gas flow rate into the single crystal furnace and / or increasing the heating power of the single crystal furnace;

[0020] When the real-time ratio is less than a preset ratio range, the gas flow rate introduced into the single crystal furnace is reduced and / or the heating power of the single crystal furnace is reduced.

[0021] In some embodiments of the present disclosure, in the process of increasing or decreasing the gas flow rate introduced into the single crystal furnace, the rate of change of the gas flow rate over time is controlled to be ≤0.4 slm / s;

[0022] In the process of increasing or decreasing the heating power of the single crystal furnace, the rate of change of the heating power over time is controlled to be ≤0.35 kW / h.

[0023] Furthermore, the present disclosure also provides a growth control device for single crystal silicon, the device comprising:

[0024] An information acquisition module, used to acquire the real-time pulling speed v of the single crystal silicon rod and the real-time temperature gradient G at the solid-liquid growth interface of the single crystal silicon rod during the pulling process of the single crystal silicon rod;

[0025] A ratio calculation module, used to calculate the real-time ratio of the real-time pulling speed v to the real-time temperature gradient G;

[0026] A ratio comparison module, used for comparing the real-time ratio with a preset ratio range;

[0027] The control module is used to adjust the real-time pulling speed v and / or the real-time temperature gradient G according to the comparison result so that the real-time ratio is within the preset ratio range.

[0028] In some embodiments of the present disclosure, the information acquisition module includes a temperature acquisition submodule and a temperature gradient calculation submodule. The temperature acquisition submodule is used to simultaneously monitor the temperatures of multiple temperature measuring points distributed in sequence in the vertical direction in the molten silicon, and the temperature gradient calculation submodule is used to calculate the real-time temperature gradient G through the temperatures of the multiple temperature measuring points and the distances between the multiple temperature measuring points.

[0029] In view of the problem that the axial temperature gradient gradually decreases as the single crystal continues to grow, some traditional technologies have proposed a technical concept of pre-obtaining the change of the axial temperature gradient G with the length of the single crystal silicon rod. This method has a limited scope of application and is time-consuming and labor-intensive. In addition, this method pre-assumes that the temperature change during each production is consistent, and cannot solve the problem of temperature gradient fluctuations caused by random factors. Therefore, there are still many defects in the produced single crystal silicon.

[0030] In the growth control method of single crystal silicon of the embodiment of the present disclosure, the real-time pulling speed v and the real-time temperature gradient G of the single crystal silicon rod are directly obtained, and the real-time ratio of the real-time pulling speed v to the real-time temperature gradient G is calculated. By controlling the real-time ratio within the preset ratio range, it is possible to ensure that the single crystal silicon always produces fewer defects during the entire crystal pulling process, thereby obtaining a single crystal silicon product with fewer single crystal defects. The growth control method of single crystal silicon realizes in-situ feedback control of the single crystal silicon during the growth process by calculating the real-time ratio of the real-time pulling speed v to the real-time temperature gradient G, and is suitable for a variety of different single crystal furnaces and crystal pulling processes. It can also avoid the process of pre-exploring process parameters in traditional technology, thereby saving exploration time and material consumption.

[0031] In addition, there is a certain degree of randomness in the actual single crystal silicon preparation process, which will cause unexpected fluctuations in the temperature gradient. Some control methods in traditional technologies are difficult to respond to the fluctuations in the temperature gradient in a timely manner. The growth control method of the single crystal silicon of the embodiment of the present disclosure can also achieve real-time adjustment for the fluctuations by obtaining the real-time ratio, thereby ensuring that the prepared single crystal silicon has good crystal quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the steps of a method for controlling the growth of single crystal silicon;

[0033] Figure 2 It is a structural schematic diagram of connecting the temperature monitoring component to the guide tube;

[0034] Figure 3 for Figure 2 A schematic diagram of the structure of multiple temperature detectors;

[0035] Figure 4 is a defect density distribution diagram of the single crystal silicon of Example 1 at 1 / 3 of the axial length;

[0036] Figure 5 is a defect density distribution diagram of the single crystal silicon of Example 1 at 1 / 2 of the axial length;

[0037] Figure 6 This is a defect density distribution diagram of the single crystal silicon of Example 1 at 3 / 4 of its length in the axial direction.

[0038] The reference numerals and their meanings are as follows:

[0039] 110. guide tube; 111. cylinder body; 112. accommodating tube connector; 120. temperature monitoring assembly; 121. accommodating tube; 122. temperature detector. DETAILED DESCRIPTION

[0040] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0042] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0043] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0044] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0045] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0046] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0047] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like 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 a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0048] In order to solve the problem that the axial temperature gradient gradually decreases as the single crystal grows, some traditional technologies have proposed a method of pre-obtaining the change of the axial temperature gradient G with the length of the single crystal silicon rod. This method has a limited scope of application and is time-consuming and labor-intensive. In addition, this method pre-assumes that the temperature change during each production is consistent, and cannot solve the problem of temperature gradient fluctuations caused by random factors. Therefore, there are still many defects in the produced single crystal silicon.

[0049] An embodiment of the present disclosure provides a growth control method for single crystal silicon, which includes the following steps: in the process of pulling a single crystal silicon rod, obtaining a real-time pulling speed v of the single crystal silicon rod, and obtaining a real-time temperature gradient G at the solid-liquid growth interface of the single crystal silicon rod. Calculating a real-time ratio of the real-time pulling speed v to the real-time temperature gradient G. And, comparing the real-time ratio with a preset ratio range, and adjusting the real-time pulling speed v and / or the real-time temperature gradient G according to the comparison result, so that the real-time ratio is within the preset ratio range.

[0050] In the growth control method of single crystal silicon of the embodiment of the present disclosure, the real-time pulling speed v and the real-time temperature gradient G of the single crystal silicon rod are directly obtained, and the real-time ratio of the real-time pulling speed v to the real-time temperature gradient G is calculated. By controlling the real-time ratio within the preset ratio range, it is possible to ensure that the single crystal silicon always produces fewer defects during the entire crystal pulling process, thereby obtaining a single crystal silicon product with fewer single crystal defects. The growth control method of single crystal silicon realizes in-situ feedback control of the single crystal silicon during the growth process by calculating the real-time ratio of the real-time pulling speed v to the real-time temperature gradient G, and is suitable for a variety of different single crystal furnaces and crystal pulling processes. It can also avoid the process of pre-exploring process parameters in traditional technology, thereby saving exploration time and material consumption.

[0051] In addition, there is a certain degree of randomness in the actual single crystal silicon preparation process, which will cause unexpected fluctuations in the temperature gradient. Some control methods in traditional technologies are difficult to respond to the fluctuations in the temperature gradient in a timely manner. The growth control method of the single crystal silicon of the embodiment of the present disclosure can also achieve real-time adjustment for the fluctuations by obtaining the real-time ratio, thereby ensuring that the prepared single crystal silicon has good crystal quality.

[0052] Figure 1 Schematic diagram of the steps of a method for controlling the growth of single crystal silicon. Figure 1 As shown, the growth control method of single crystal silicon includes steps S1 to S3, which are specifically as follows.

[0053] Step S1, during the pulling process of the single crystal silicon rod, obtaining the real-time pulling speed v of the single crystal silicon rod, and obtaining the real-time temperature gradient G at the solid-liquid growth interface of the single crystal silicon rod.

[0054] It can be understood that the pulling process of the single crystal silicon rod refers to the process of slowly pulling the seed crystal after dropping the seed crystal into the molten silicon, and allowing the molten silicon to grow to form a new single crystal silicon based on the seed crystal. The solid-liquid interface refers to the interface between the molten silicon and the single crystal silicon rod. In this embodiment, the real-time pulling speed v of the single crystal silicon rod refers to the speed at which the single crystal silicon rod is pulled upward from the solid-liquid interface at a certain moment, which is equivalent to the moving speed of the pulling head. The real-time temperature gradient G refers to the rate of change of temperature near the solid-liquid growth interface with position at a certain moment.

[0055] As an example of this embodiment, the real-time pulling speed v of the single crystal silicon rod is obtained by measuring the moving speed of the pulling head and taking the moving speed of the pulling head as the real-time pulling speed v of the single crystal silicon rod.

[0056] As an example of this embodiment, the method of obtaining the real-time temperature gradient G at the solid-liquid growth interface of the single crystal silicon rod includes: simultaneously monitoring the temperatures of multiple temperature measuring points distributed in sequence in the vertical direction in the molten silicon; and calculating the real-time temperature gradient G through the temperatures of the multiple temperature measuring points and the distances between the multiple temperature measuring points. It can be understood that when calculating the real-time temperature gradient G, the real-time temperature gradient G can be obtained by calculating the temperature difference of different temperature measuring points and dividing it by the distance between the corresponding temperature measuring points.

[0057] In this example, the temperature measurement point is located inside the molten silicon. The molten silicon has an extremely high temperature, and how to avoid the influence of temperature measurement on the growth of single crystal silicon becomes a difficulty in temperature measurement. The present disclosure further provides the following implementation method.

[0058] As an example of this embodiment, a temperature monitoring component 120 may be used to monitor the temperatures of multiple temperature measurement points simultaneously. The temperature monitoring component 120 includes a containing tube 121 and a plurality of temperature detectors 122 disposed in the containing tube 121 .

[0059] As a further example of this embodiment, in order to ensure that the temperature measurement point is fixed relative to the solid-liquid growth interface, the temperature monitoring component 120 can be detachably connected to the guide tube 110 of the single crystal furnace. Figure 2 This is a schematic diagram of the structure of connecting the temperature monitoring assembly 120 to the guide tube 110, referring to Figure 2 As shown, the accommodating tube 121 of the temperature monitoring assembly 120 is detachably connected to the guide tube 110 , and the temperature detector 122 is disposed in the accommodating tube 121 . Figure 3 for Figure 2 A schematic diagram of the structure of multiple temperature detectors 122. Figure 2 and Figure 3 As shown, the containing tube 121 is immersed in molten silicon, and a plurality of temperature detectors 122 are respectively located at a plurality of temperature measuring points. Optionally, the temperature detectors 122 are in contact with the inner wall of the containing tube 121 .

[0060] In this example, the accommodating tube 121 can isolate the molten silicon from the temperature detector 122 to prevent the temperature detector 122 from contaminating the molten silicon or being contaminated by the molten silicon. In addition, the accommodating tube 121 can transfer the heat of the molten silicon to the temperature detector 122 therein, so that the temperature detector 122 can detect the temperature of the molten silicon at the temperature measurement point.

[0061] Combination Figure 2 and Figure 3As shown, when the containing tube 121 is connected to the guide tube 110, the multiple temperature detectors 122 in the containing tube 121 are all located below the bottom wall of the guide tube 110. The single crystal furnace for growing single crystal silicon includes a crucible and a guide tube 110, and the guide tube 110 is arranged above the molten silicon. The guide tube 110 is used to improve the flow of the melt, control the temperature distribution on the surface of the melt, and prevent impurities from contaminating the molten silicon in the crucible. The containing tube 121 located below the bottom wall of the guide tube 110 can extend into the molten silicon. During the pulling process of single crystal silicon, the position of the guide tube 110 is basically fixed relative to the position of the molten silicon surface. Therefore, connecting the containing tube 121 to the guide tube 110 can ensure that the temperature measuring point is fixed relative to the position of the solid-liquid growth interface as much as possible.

[0062] Combination Figure 2 and Figure 3 As shown, as an example of this embodiment, the accommodating tube 121 can be detachably connected to the guide tube 110 by threaded connection.

[0063] As an example of this embodiment, the material of the containing tube 121 may be quartz. The melting point of quartz is higher than that of silicon, and it can withstand the temperature of molten silicon. The material of the crucible used to hold molten silicon is usually quartz. Using quartz as the material of the containing tube 121 can avoid impurities introduced during the temperature measurement process as much as possible.

[0064] In order to be compatible with the temperature monitoring assembly 120, the structure of the guide tube 110 in this embodiment may also be configured accordingly. Figure 2 and Figure 3 As shown, as an example of this embodiment, the guide tube 110 includes a cylinder 111 and a receiving tube connector 112, the receiving tube connector 112 is arranged on the outer wall of the cylinder 111, and the receiving tube 121 is detachably connected to the receiving tube connector 112. Among them, the receiving tube connector 112 is in a hollow tube shape, and the temperature monitoring component 120 also includes a signal transmission line, one end of which is connected to the temperature detector 122. When the receiving tube 121 is connected to the receiving tube connector 112, the signal transmission line can be arranged in the pipeline of the receiving tube connector 112.

[0065] Combination Figure 2 and Figure 3 As shown, in this example, the accommodating tube connector 112 is arranged on the side wall of the cylinder 111, and the accommodating tube 121 is correspondingly located below the side wall of the cylinder 111. The single crystal silicon rod is located inside the cylinder 111 of the guide cylinder 110. Therefore, this structural design can avoid the influence of the temperature monitoring component 120 on the pulling process of the single crystal silicon rod. In addition, the hollow accommodating tube connector 112 is also used to fix the signal transmission line, which can ensure that the temperature monitored by the temperature monitoring component 120 can be normally transmitted to the external functional module.

[0066] It can be understood that, in the temperature monitoring component 120 , the number of temperature measuring points corresponds to the number of temperature detectors 122 , and each temperature detector 122 is used to detect the temperature of one temperature measuring point.

[0067] Combination Figure 2 and Figure 3 As shown in the figure, as an example of this embodiment, there are three temperature measuring points, and accordingly, three temperature detectors 122 are also provided in the containing tube 121. For the convenience of explanation, along the direction away from the solid-liquid growth interface, the three temperature measuring points are successively recorded as point A, point B and point C, where point B is located between point A and point C. During the growth process of single crystal silicon, the temperatures measured at point A, point B and point C are respectively recorded as T A 、T B 、T C , the distance between point A and point B is recorded as D AB , the distance between point B and point C is recorded as D BC The real-time temperature gradient G is calculated using the following formula:

[0068]

[0069] In the calculation method of the real-time temperature gradient G, the temperature change rate between point A and point B, the temperature change rate between point B and point C, and the temperature change rate between point A and point C are calculated respectively, and the above three temperature change rates are averaged to serve as the real-time temperature gradient G. Compared with two temperature measuring points, by setting three temperature measuring points and adopting the above calculation method to calculate the real-time temperature gradient G, the obtained real-time temperature gradient G is less affected by random factors and the result is more accurate. When there are more than three temperature measuring points, some temperature measuring points are far away from the solid-liquid growth interface, which will cause the calculated result to have a certain deviation from the actual temperature gradient near the solid-liquid growth interface. Therefore, setting three temperature measuring points and adopting the above calculation method can more accurately reflect the real-time temperature gradient G.

[0070] As an example of this embodiment, among the multiple temperature measurement points, the distance between the temperature measurement point closest to the solid-liquid growth interface and the solid-liquid growth interface is ≤20 mm. Figure 2 and Figure 3 As shown, in this example, the temperature measurement point closest to the solid-liquid growth interface is point A.

[0071] Optionally, the distance between the temperature measurement point closest to the solid-liquid growth interface and the solid-liquid growth interface can be 10 mm to 15 mm. For example, the distance between the temperature measurement point closest to the solid-liquid growth interface and the solid-liquid growth interface is 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, or the distance between the temperature measurement point closest to the solid-liquid growth interface and the solid-liquid growth interface can also be between any two of the above distances.

[0072] As an example of this embodiment, among the multiple temperature measurement points, the distance between the temperature measurement point farthest from the solid-liquid growth interface and the solid-liquid growth interface is ≤150 mm. Figure 2 and Figure 3 As shown, in this example, the temperature measurement point closest to the solid-liquid growth interface is point C.

[0073] Optionally, the distance between the temperature measurement point farthest from the solid-liquid growth interface and the solid-liquid growth interface can be 135 mm to 145 mm. For example, the distance between the temperature measurement point farthest from the solid-liquid growth interface and the solid-liquid growth interface is 135 mm, 137 mm, 139 mm, 140 mm, 141 mm, 143 mm, 145 mm, or the distance between the temperature measurement point farthest from the solid-liquid growth interface and the solid-liquid growth interface can also be between any two of the above distances.

[0074] As an example of this embodiment, the spacing between any two adjacent temperature measurement points is 10 mm to 50 mm. For example, the spacing between any two adjacent temperature measurement points is 10 mm, 20 mm, 30 mm, 40 mm, or 50 mm, or the spacing between any two adjacent temperature measurement points can also be between any two of the above spacings.

[0075] It can be understood that in the growth control method of single crystal silicon, the following Figure 3 The guide tube 110 and the temperature monitoring assembly 120 shown can simultaneously monitor the temperatures of multiple temperature measuring points distributed in the vertical direction in the molten silicon. Then, a device including but not limited to a computer can be used to calculate the temperatures of the multiple temperature measuring points and the distances between the multiple temperature measuring points, and obtain the real-time temperature gradient G.

[0076] Step S2, calculating the real-time ratio of the real-time pulling speed v to the real-time temperature gradient G.

[0077] It can be understood that the real-time pulling speed v and the real-time temperature gradient G should be values ​​obtained at the same time. The real-time ratio can be calculated by v / G, and the calculation process can be implemented by devices including but not limited to computers.

[0078] Step S3, comparing the real-time ratio with the preset ratio range, and adjusting the real-time pulling speed v and / or adjusting the real-time temperature gradient G according to the comparison result, so that the real-time ratio is within the preset ratio range.

[0079] It is understood that the preset ratio range can be predicted based on known content, or can be derived based on the work experience of technicians. Among them, the preset ratio range has different upper and lower limits. When the real-time ratio is greater than the upper limit of the preset ratio range, the real-time ratio can be reduced so that the real-time ratio is within the preset ratio range. When the real-time ratio is less than the lower limit of the preset ratio range, the real-time ratio can be increased so that the real-time ratio is within the preset ratio range.

[0080] As an example of this embodiment, the difference between the upper limit and the lower limit of the preset ratio range is ≤ 0.006 mm. 2 / (min·K).

[0081] As an example of this embodiment, the preset ratio range may be 0.135 mm 2 / (min·K)~0.141mm 2 / (min·K). It is generally believed that the ratio of the pulling speed of single crystal silicon to the temperature gradient is about 0.138mm 2 / (min·K) can be in a relatively ideal growth state for the single crystal silicon. The use of this preset ratio range can ensure that the prepared single crystal silicon has significantly lower defects.

[0082] In addition, in some traditional technologies that use software simulation to obtain temperature gradients, a relatively large preset ratio range is usually used. This is mainly because the predicted temperature gradient obtained by software simulation often deviates from the actual temperature gradient, and thus the predicted ratio obtained also deviates from the actual ratio. At this time, if a smaller preset ratio range is used, it is easy to cause frequent changes in process parameters, which is not conducive to reducing defects in single crystal silicon. This embodiment directly measures the real-time temperature gradient G during the growth of single crystal silicon, and the deviation between the calculated real-time ratio and the actual ratio is small. Using a smaller preset ratio range is actually conducive to reducing defects in single crystal silicon.

[0083] In the actual growth process of single crystal silicon, the pulling speed v of single crystal silicon will also indirectly affect the diameter of the prepared single crystal silicon material and the temperature at the solid-liquid growth interface, thereby increasing the difficulty of regulating the temperature gradient G. In addition, if the pulling speed v of single crystal silicon is reduced, the production efficiency of single crystal silicon will also decrease. Therefore, as an example of this embodiment, when adjusting the real-time pulling speed v and / or adjusting the real-time temperature gradient G according to the comparison result, the real-time pulling speed v is kept unchanged, and only the real-time temperature gradient G is adjusted so that the real-time ratio is within the preset ratio range. This can maintain the stable quality and production efficiency of single crystal silicon.

[0084] As a further example of this embodiment, the step of adjusting the real-time temperature gradient G includes: when the real-time ratio is greater than a preset ratio range, increasing the gas flow rate entering the single crystal furnace and / or increasing the heating power of the single crystal furnace; when the real-time ratio is less than the preset ratio range, reducing the gas flow rate entering the single crystal furnace and / or reducing the heating power of the single crystal furnace.

[0085] In this example, the gas introduced into the single crystal furnace can promote heat conduction on the surface of the molten silicon, so increasing the gas flow rate is conducive to increasing the real-time temperature gradient G, which is conducive to reducing the real-time ratio. On the contrary, reducing the gas flow rate is conducive to increasing the real-time ratio. Increasing the heating power of the single crystal furnace can promote the temperature at the bottom of the molten silicon, so increasing the heating power is also conducive to increasing the real-time temperature gradient G, which is conducive to reducing the real-time ratio. On the contrary, reducing the heating power is conducive to increasing the real-time ratio.

[0086] Furthermore, in the process of increasing or decreasing the gas flow rate introduced into the single crystal furnace, the change of the gas flow rate should not be too fast, otherwise it will cause a significant change in the instantaneous real-time temperature gradient G, thereby causing a large number of defects in the local area of ​​the single crystal silicon. As an example of this embodiment, in the process of increasing or decreasing the gas flow rate introduced into the single crystal furnace, the rate of change of the gas flow rate over time is controlled to be ≤0.4slm / s.

[0087] Furthermore, in the process of increasing or decreasing the heating power of the single crystal furnace, the change of the heating power should not be too fast, otherwise it will cause a significant change in the instantaneous real-time temperature gradient G, thereby causing a large number of defects in the local area of ​​the single crystal silicon. As an example of this embodiment, in the process of increasing or decreasing the heating power of the single crystal furnace, the rate of change of the heating power over time is controlled to be ≤0.35kW / h.

[0088] It can be understood that after the above steps S1 to S3, the growth control method for single crystal silicon of this embodiment can be completed. The preparation of single crystal silicon based on the growth control method of single crystal silicon can reduce the overall defect amount of single crystal silicon and obtain single crystal silicon with better quality. The growth control method of single crystal silicon realizes in-situ feedback control of single crystal silicon during the growth process by calculating the real-time ratio of the real-time pulling speed v and the real-time temperature gradient G, and is suitable for a variety of different single crystal furnaces and crystal pulling processes. It can also avoid the process of pre-exploring process parameters in traditional technology, thereby saving exploration time and material consumption.

[0089] An embodiment of the present disclosure also provides a growth control device for single crystal silicon. The growth control device includes: an information acquisition module, a calculation module, a ratio comparison module and a control module. Among them, the information acquisition module is used to obtain the real-time pulling speed v of the single crystal silicon rod and the real-time temperature gradient G at the solid-liquid growth interface of the single crystal silicon rod during the pulling process of the single crystal silicon rod. The ratio calculation module is used to calculate the real-time ratio of the real-time pulling speed v and the real-time temperature gradient G. The ratio comparison module is used to compare the real-time ratio with a preset ratio range. The control module is used to adjust the real-time pulling speed v and / or the real-time temperature gradient G according to the comparison result so that the real-time ratio is within the preset ratio range.

[0090] As an example of this embodiment, the information acquisition module includes a temperature acquisition submodule and a temperature gradient calculation submodule. The temperature acquisition submodule is used to simultaneously acquire the temperatures of multiple temperature measuring points distributed in sequence in the vertical direction in the molten silicon. The temperature gradient calculation submodule is used to calculate the real-time temperature gradient G through the temperatures of multiple temperature measuring points and the distances between the multiple temperature measuring points.

[0091] As a further example of this embodiment, the temperature acquisition submodule signal is connected to Figure 2 In the temperature monitoring component, the temperature acquisition submodule acquires the temperature measured by the temperature detector therein as the temperature of multiple temperature measurement points.

[0092] As a further example of this embodiment, the temperature acquisition submodule is used to acquire the temperatures of three temperature measurement points, which are respectively recorded as point A, point B and point C, point B is located between point A and point C, and the temperatures measured at point A, point B and point C are respectively recorded as T A 、T B 、T C , the distance between point A and point B is recorded as D AB , the distance between point B and point C is recorded as D BC The temperature gradient calculation submodule uses the following formula to calculate the real-time temperature gradient G:

[0093]

[0094] The present application is further described in detail below in conjunction with several specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0095] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0096] Example 1: Preparation of doped N-type single crystal

[0097] The diameter of the grown silicon single crystal is between 200mm and 300mm, and the crystal orientation is <100> During the crystal pulling process, argon gas is introduced into the single crystal furnace. The argon gas flow rate is between 80slm and 120slm, the crystal rotation speed is 4rpm to 10rpm, and the crucible rotation speed is 3rpm to 6rpm. Figure 2 and Figure 3 The temperature monitoring assembly shown is connected to the guide tube and extends into the molten silicon to measure the temperature in real time.

[0098] During the process of pulling single crystal silicon, the real-time pulling speed v of the single crystal silicon is monitored, the real-time temperature gradient G near the solid-liquid interface is obtained, and the real-time ratio v / G is calculated. The ratio range is set to 0.135mm 2 / (min·K)~0.141mm 2 / (min·K). When the real-time ratio is greater than 0.141mm 2 / (min·K), increase the argon flow rate and heating power. When the real-time ratio is less than 0.135mm 2 / (min·K), reduce the argon flow rate and heating power. For example, at a certain moment, the real-time pulling speed v is 95mm / min, and the real-time temperature gradient G is 655K / mm, then v / G is 0.145mm 2 / (min·K), at this time, reduce the argon flow rate and heating power to make v / G close to 0.138mm 2 / (min·K).

[0099] After the single crystal silicon is pulled, single crystal silicon samples are cut at 1 / 3, 1 / 2 and 3 / 4 of the axial length, wet-etched and characterized by TEM to measure the defect density of the current silicon wafer in the thickness direction. The results are shown in Figures 4 to 6 . Figures 4 to 6 The horizontal axis unit is μm, which indicates the distance between the test point and the surface, and the vertical axis unit is pieces / cm 2 , represents the defect density.

[0100] Reference Figure 4 As shown, at 1 / 3 of the length of the single crystal silicon sample, which corresponds to the stage where the pulling speed rises to a stable state, the number of vacancy defects and interstitial defects is basically equal, and they can form a better composite and cancel each other out.

[0101] Reference Figure 5 As shown, at 1 / 2 length of the single crystal silicon sample, this corresponds to a stable stage with a higher pulling speed. In this stage, the real-time temperature gradient G is dynamically adjusted. At this time, the number of interstitial defects is slightly higher than the number of vacancy defects. Although they cannot be completely eliminated by compounding, the total amount of defects can be controlled within a lower range.

[0102] Reference Figure 6 As shown, at 3 / 4 of the length of the single crystal silicon sample, which corresponds to the finishing stage, the number of vacancy defects is slightly higher than the number of gap defects, and the total defect amount can also be controlled to be low.

[0103] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for controlling the growth of single crystal silicon, characterized in that: The following steps are involved: During the pulling process of the single crystal silicon rod, obtaining the real-time pulling speed v of the single crystal silicon rod and obtaining the real-time temperature gradient G at the solid-liquid growth interface of the single crystal silicon rod; Calculating a real-time ratio of the real-time pulling speed v to the real-time temperature gradient G; as well as, The real-time ratio is compared with a preset ratio range, and the real-time pulling speed v and / or the real-time temperature gradient G are adjusted according to the comparison result so that the real-time ratio is within the preset ratio range.

2. The method for controlling the growth of single crystal silicon according to claim 1, characterized in that: The method of obtaining the real-time temperature gradient G at the solid-liquid growth interface of the single crystal silicon rod includes: Simultaneously monitoring the temperatures of a plurality of temperature measuring points sequentially distributed in the vertical direction in the molten silicon; The real-time temperature gradient G is calculated based on the temperatures of the multiple temperature measuring points and the distances between the multiple temperature measuring points.

3. The method for controlling the growth of single crystal silicon according to claim 2, characterized in that: Among the multiple temperature measuring points, the distance between the temperature measuring point closest to the solid-liquid growth interface and the solid-liquid growth interface is ≤20 mm, and the distance between the temperature measuring point farthest from the solid-liquid growth interface and the solid-liquid growth interface is ≤150 mm.

4. The method for controlling the growth of single crystal silicon according to claim 3, characterized in that: The distance between any two adjacent temperature measuring points is 10 mm to 50 mm.

5. The method for controlling the growth of single crystal silicon according to claim 2, characterized in that: There are three temperature measurement points, which are respectively recorded as point A, point B and point C. Point B is located between point A and point C. The temperatures measured at point A, point B and point C are respectively recorded as T A , T B , T C , the distance between point A and point B is recorded as D AB , the distance between point B and point C is recorded as D BC ; The real-time temperature gradient G is calculated using the following formula:

6. The method for controlling the growth of single crystal silicon according to any one of claims 1 to 5, characterized in that: The preset ratio range is 0.135mm 2 / (min·K)~0.141mm 2 / (min·K).

7. The method for controlling the growth of single crystal silicon according to any one of claims 1 to 5, characterized in that: In the step of adjusting the real-time pulling speed v and / or adjusting the real-time temperature gradient G according to the comparison result, the real-time pulling speed v is kept unchanged, and only the real-time temperature gradient G is adjusted. The step of adjusting the real-time temperature gradient G includes: When the real-time ratio is greater than a preset ratio range, increasing the gas flow rate into the single crystal furnace and / or increasing the heating power of the single crystal furnace; When the real-time ratio is less than a preset ratio range, the gas flow rate introduced into the single crystal furnace is reduced and / or the heating power of the single crystal furnace is reduced.

8. The method for controlling the growth of single crystal silicon according to claim 7, characterized in that: In the process of increasing or decreasing the gas flow rate into the single crystal furnace, the rate of change of the gas flow rate over time is controlled to be ≤0.4 slm / s; In the process of increasing or decreasing the heating power of the single crystal furnace, the rate of change of the heating power over time is controlled to be ≤0.35 kW / h.

9. A growth control device for single crystal silicon, characterized in that: The device comprises: An information acquisition module, used to acquire the real-time pulling speed v of the single crystal silicon rod and the real-time temperature gradient G at the solid-liquid growth interface of the single crystal silicon rod during the pulling process of the single crystal silicon rod; A ratio calculation module, used to calculate the real-time ratio of the real-time pulling speed v to the real-time temperature gradient G; A ratio comparison module, used for comparing the real-time ratio with a preset ratio range; The control module is used to adjust the real-time pulling speed v and / or the real-time temperature gradient G according to the comparison result so that the real-time ratio is within the preset ratio range.

10. The growth control device for single crystal silicon according to claim 9, characterized in that: The information acquisition module includes a temperature acquisition submodule and a temperature gradient calculation submodule. The temperature acquisition submodule is used to simultaneously monitor the temperatures of multiple temperature measuring points distributed in sequence in the vertical direction in the molten silicon, and the temperature gradient calculation submodule is used to calculate the real-time temperature gradient G through the temperatures of the multiple temperature measuring points and the distances between the multiple temperature measuring points.

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