A method for detecting the diameter of a silicon rod in a single crystal silicon rod production process

Abstract

The application discloses a method for detecting the diameter of a silicon rod in a single crystal silicon rod preparation process, which comprises the following steps: obtaining a detection image of a silicon rod aperture; determining the detection positions of a pre-equal-diameter diameter detection frame and a post-equal-diameter diameter detection frame in the detection image; connecting the detection results of the pre-equal-diameter diameter detection frame and the post-equal-diameter diameter detection frame and determining a connection ratio K; before the connection ratio K is determined, calculating the aperture diameter of the silicon rod aperture according to the silicon rod aperture within the range of the pre-equal-diameter diameter detection frame; after the connection ratio K is determined, calculating the aperture diameter of the silicon rod aperture according to the silicon rod aperture within the range of the post-equal-diameter diameter detection frame and the connection ratio K; and calculating the diameter of the silicon rod according to the aperture diameter of the silicon rod aperture. The application has the advantages of improving the measurement accuracy of the diameter of the silicon rod, reducing the fluctuation of the diameter of the silicon rod and being suitable for more different situations in which the silicon rod aperture is shielded.

Description

Technical Field

[0001] This invention relates to the process of preparing single-crystal silicon rods, and more particularly, to a method for detecting the diameter of silicon rods during the preparation of single-crystal silicon rods. Background Technology

[0002] The Czochralski method, the most commonly used process for preparing single-crystal silicon rods, involves filling a silicon crucible with polycrystalline silicon, heating it to melt and form a silicon material, immersing a seed crystal in the silicon material, and then rotating and pulling it upwards to obtain a silicon rod. The stages involved include: temperature stabilization, crystal pulling, shoulder formation, shoulder rotation, and diameter equalization. Except for temperature stabilization, each stage requires the silicon rod diameter as negative feedback to guide the control system in controlling the growth of the silicon rod.

[0003] Please see Figure 1 The figure shows an existing silicon rod diameter detection system. The system includes a furnace body 1, a flow guide tube 2, a silicon material crucible 3, and an industrial camera 4. The flow guide tube 2 and the silicon material crucible 3 are both located inside the furnace body 1. The industrial camera 4 is positioned at an angled observation window within the furnace body 1. The industrial camera 4 performs visual inspection of the silicon rod's aperture. The working principle is roughly as follows: during silicon rod growth, the temperature at the interface between the silicon material surface and the silicon rod is higher than at other locations on the silicon material surface. Therefore, the image brightness at this interface is relatively high in the detection image, forming a silicon rod aperture. The change in the diameter of the silicon rod aperture can indirectly reflect the change in the silicon rod's diameter; therefore, the silicon rod diameter can be measured by measuring the silicon rod aperture. Currently, the method used is to directly obtain the diameter data using a fitted circle or fitted ellipse.

[0004] The applicant found that, especially at the end of the constant diameter stage, the visible part of the silicon rod aperture is very small, the number of points involved in the fitting is small and unevenly distributed, which affects the fitting results and causes large fluctuations in the diameter of the silicon rod, resulting in slightly uneven surface defects in the silicon rod obtained by the Czochralski method. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of large fluctuations in the diameter of silicon rods in the visual inspection of existing technologies, and to provide a novel visual inspection method for the diameter of silicon rods during the preparation of single-crystal silicon rods.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A method for detecting the diameter of a silicon rod during the preparation of a single-crystal silicon rod, comprising:

[0007] Obtain detection images of the silicon rod aperture;

[0008] Determine the fixed positions of the pre-diameter detection frame and the post-diameter detection frame in the detection image;

[0009] Connect the equal-diameter front diameter detection frame and the equal-diameter rear diameter detection frame, and determine the connection ratio K;

[0010] Before the connection ratio K is determined, the aperture diameter of the silicon rod aperture is calculated based on the silicon rod aperture within the equal diameter front diameter detection frame; after the connection ratio K is determined, the aperture diameter of the silicon rod aperture is calculated based on the silicon rod aperture within the equal diameter rear diameter detection frame and the connection ratio K; and,

[0011] The diameter of the silicon rod is calculated based on the aperture diameter of the silicon rod aperture.

[0012] As a preferred embodiment of a silicon rod diameter detection method in the process of preparing single-crystal silicon rods, the silicon rod diameter detection method is based on the design of a silicon rod diameter detection system. The silicon rod diameter detection system includes: a system furnace body, a flow guide tube, a silicon material crucible, and an industrial camera. The flow guide tube and the silicon material crucible are both arranged inside the system furnace body. The industrial camera is arranged at the oblique observation window position of the system furnace body, and the industrial camera performs visual inspection of the silicon rod aperture.

[0013] As a preferred embodiment of a method for detecting the diameter of a silicon rod during the preparation of a single-crystal silicon rod, the pre-diameter detection frame is determined during the crystal pulling stage of the silicon rod.

[0014] As a preferred embodiment of a method for detecting the diameter of a silicon rod during the preparation of a single-crystal silicon rod, the step of determining the diameter detection frame before the equal diameter includes: the silicon rod aperture at this time has a ring structure;

[0015] Determine the equal-diameter pre-positioner: the equal-diameter pre-positioner is a straight line passing through the center point of the aperture of the silicon rod, and the straight line is perpendicular to the silicon rod in the detection image; and...

[0016] Based on the equal diameter front locator, the fixed position of the equal diameter front diameter detection frame is determined.

[0017] As a preferred embodiment of a method for detecting the diameter of a silicon rod during the preparation of a single-crystal silicon rod, the diameter detection frame after equalization is determined during the shoulder-forming stage, the shoulder-turning stage, or the equalization stage of the silicon rod.

[0018] As a preferred embodiment of a method for detecting the diameter of a silicon rod during the preparation of a single-crystal silicon rod, the step of determining the diameter detection frame after equal diameter includes: the silicon rod aperture at this time has an eight-shaped structure, including: an aperture flare and an aperture slant;

[0019] After determining the equal-diameter positioning device: the equal-diameter positioning device is a straight line passing through two points; one point is the intersection of the line connecting the center point of the silicon rod aperture and the positioning point of the flared portion of the aperture with the outer edge of the flared portion of the aperture; the other point is the intersection of the line connecting the center point of the silicon rod aperture and the positioning point of the slant portion of the aperture with the outer edge of the slant portion of the aperture with the outer edge of the slant portion of the aperture; and,

[0020] Based on the equal-diameter post-positioner, the fixed position of the equal-diameter post-diameter detection frame is determined.

[0021] Compared with the prior art, the beneficial effects of the present invention are at least as follows: improving the measurement accuracy of silicon rod diameter, reducing the fluctuation of silicon rod diameter, and being able to adapt to more different situations where the aperture of silicon rod is blocked, thereby improving the success rate of Czochralski pulling of single crystal silicon rods.

[0022] In addition to the technical problems solved by the present invention, the technical features constituting the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions as described above, other technical problems that the present invention can solve, other technical features contained in the technical solutions, and the beneficial effects brought about by these technical features will be further described in detail with reference to the accompanying drawings. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the existing technology.

[0024] Figure 2 This is a flowchart of a method according to an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of an equal-diameter front positioner according to an embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram of a constant diameter rear positioner according to an embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram of a front diameter detection frame and a rear diameter detection frame with equal diameter according to an embodiment of the present invention. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. It should be noted that these descriptions of embodiments are intended to aid in understanding the invention and do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] Please see Figure 1The figure shows an existing silicon rod diameter detection system. The system includes: a furnace body 1, a flow guide tube 2, a silicon material crucible 3, and an industrial camera 4. The flow guide tube 2 and the silicon material crucible 3 are both located inside the furnace body 1. The industrial camera 4 is positioned at an angled observation window within the furnace body 1. The industrial camera 4 performs visual inspection of the silicon rod's aperture.

[0030] Please see Figure 2 The figure illustrates a method for detecting the diameter of a silicon rod during the fabrication of a single-crystal silicon rod, designed based on the aforementioned silicon rod diameter detection system. The specific methods for visually detecting the diameter of the silicon rod include:

[0031] Obtain a detection image of the aperture 6 of the silicon rod.

[0032] Determine the fixed positions of the pre-diameter detection frame 10 and the post-diameter detection frame 20 in the detection image.

[0033] Connect the equal-diameter front diameter detection frame 10 and the equal-diameter rear diameter detection frame 20, and determine the connection ratio K. The connection ratio K represents the calculated ratio of the equal-diameter front diameter detection frame 10 and the equal-diameter rear diameter detection frame 20 with respect to the aperture diameter of the silicon rod aperture 6.

[0034] Before the connection ratio K is determined, the aperture diameter of the silicon rod aperture 6 is calculated based on the silicon rod aperture 6 within the range of the equal diameter front diameter detection frame 10. After the connection ratio K is determined, the aperture diameter of the silicon rod aperture 6 is calculated based on the silicon rod aperture 6 within the range of the equal diameter rear diameter detection frame 20 and the connection ratio K.

[0035] The diameter of the silicon rod is calculated based on the aperture diameter of the aperture 6 of the silicon rod.

[0036] Please see Figure 3 The equal-diameter pre-diameter detection frame 10 is determined during the silicon rod's crystal pulling stage. At this time, the silicon rod aperture 6 has a ring structure. The determination steps specifically include:

[0037] Determine the center point A1 of the aperture of the silicon rod aperture 6.

[0038] Determine the equal diameter front positioner A2: The equal diameter front positioner A2 is a straight line passing through the center point A1 of the aperture of the silicon rod aperture 6 and the straight line is perpendicular to the silicon rod 5 in the detection image.

[0039] Based on the equal diameter front locator A2, the fixed position of the equal diameter front diameter detection frame 10 is determined.

[0040] Please see Figure 4The diameter detection frame 20 after equalization is determined during the shoulder-forming stage, shoulder-turning stage, or equalization stage of the silicon rod. At this time, the silicon rod aperture 6 changes from annular to figure-eight shaped, including: an aperture flared portion and an aperture slant portion. The specific steps for determination include:

[0041] The positioning points A3 and A4 of the aperture's left-falling and right-falling portions are determined as follows: In this embodiment, the center of the outer rectangle of the aperture's left-falling portion is used as the positioning point A3, and the center of the outer rectangle of the aperture's right-falling portion is used as the positioning point A4. In other embodiments, the positions of the above positioning points are not limited to this and can be adjusted adaptively.

[0042] After determining the equal diameter positioning device A7: The equal diameter positioning device A7 is a straight line passing through two points A5 and A6. One point A5 is the intersection of the line connecting the center point A1 of the silicon rod aperture 6 and the positioning point A3 of the aperture's flared portion with the outer edge of the aperture's flared portion. The other point A6 is the intersection of the line connecting the center point A1 of the silicon rod aperture 6 and the positioning point A4 of the aperture's downward-facing portion with the outer edge of the aperture's downward-facing portion.

[0043] Based on the equal diameter post locator A7, the fixed position of the equal diameter post diameter detection frame 20 is determined.

[0044] Please see Figure 5 Determining the connection ratio K requires collecting two sets of data. In this embodiment, the first set of data comes from the equal-diameter front diameter detection frame 10, that is, the length of the rectangle circumscribed by the silicon rod aperture 6. The second set of data comes from the equal-diameter detection frame 20, that is, the length of the rectangle circumscribed by the silicon rod aperture 6. The connection ratio K is the ratio of the two mentioned above. In other embodiments, both sets of data come from the equal-diameter detection frame 20, in which case... ,in This is the ratio from the last data connection. This usually happens when the appropriate detection position changes after the silicon rod has grown for a period of time, and the connection needs to be re-established.

[0045] In this embodiment, before the connection ratio K is determined, the aperture diameter of the silicon rod aperture 6 is equal to the length of the rectangle circumscribed by the silicon rod aperture 6 within the range of the equal-diameter pre-diameter detection frame 10. After the connection ratio K is determined, the aperture diameter of the silicon rod aperture 6 is equal to the length of the rectangle circumscribed by the silicon rod aperture 6 within the range of the equal-diameter post-diameter detection frame 20 multiplied by the connection ratio K. Thus, a simple and reliable circumscribed rectangle method replaces the circle fitting and ellipse fitting algorithms, which are significantly affected by the amount of data, thereby improving the robustness of diameter detection, reducing diameter data fluctuations, and ultimately resulting in a smoother surface on the grown silicon rod.

[0046] In other embodiments, the aperture diameter of the silicon rod aperture 6 can also be replaced by any of the following methods: spot positioning, straight line positioning, line positioning, pixel projection, circle fitting, ellipse fitting.

[0047] The above description merely illustrates embodiments of the present invention and is quite specific and detailed; however, it should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this invention should be determined by the appended claims.

Claims

1. A method for detecting the diameter of a silicon rod during the preparation of a single-crystal silicon rod, characterized in that, include: Obtain detection images of the silicon rod aperture; Determine the detection positions of the pre-diameter detection frame and the post-diameter detection frame in the detection image; The detection results of the equal diameter detection frame before and after the equal diameter detection frame are connected, and the connection ratio K is determined. Before the connection ratio K is determined, the aperture diameter of the silicon rod aperture is calculated based on the silicon rod aperture within the equal diameter front diameter detection frame; after the connection ratio K is determined, the aperture diameter of the silicon rod aperture is calculated based on the silicon rod aperture within the equal diameter rear diameter detection frame and the connection ratio K; and, The diameter of the silicon rod is calculated based on the aperture diameter of the silicon rod aperture. The equal diameter pre-diameter detection frame is determined during the silicon rod's crystal pulling stage. The steps for determining the equal diameter pre-diameter detection frame include: determining the equal diameter pre-positioner: the equal diameter pre-positioner is a straight line passing through the center point of the aperture of the silicon rod aperture; and determining the detection position of the equal diameter pre-diameter detection frame based on the equal diameter pre-positioner. The equal-diameter detection frame is determined during the shoulder-forming stage, shoulder-turning stage, or equal-diameter stage of the silicon rod. The steps for determining the diameter detection frame after equal diameter measurement include: the silicon rod aperture at this time has an eight-shaped structure, including: an aperture flare and an aperture dot; determining the equal diameter positioning device: the equal diameter positioning device is a straight line passing through two points; one point is the intersection of the line connecting the center point of the silicon rod aperture and the positioning point of the flare of the aperture flare with the outer edge of the flare of the aperture, and the other point is the intersection of the line connecting the center point of the silicon rod aperture and the positioning point of the dot of the aperture dot with the outer edge of the dot of the aperture; and, based on the equal diameter positioning device, determining the detection position of the equal diameter detection frame; Before the connection ratio K is determined, the aperture diameter of the silicon rod aperture is equal to the length of the smallest circumscribed rectangle of the silicon rod aperture within the range of the equal diameter pre-diameter detection frame; after the connection ratio K is determined, the aperture diameter of the silicon rod aperture is equal to the length of the smallest circumscribed rectangle of the silicon rod aperture within the range of the equal diameter post-diameter detection frame multiplied by the connection ratio K.

2. The method for detecting the diameter of a silicon rod during the preparation of a single-crystal silicon rod according to claim 1, characterized in that, The silicon rod diameter detection method is based on a silicon rod diameter detection system design. The silicon rod diameter detection system includes: a system furnace body, a flow guide tube, a silicon material crucible, and an industrial camera. The flow guide tube and the silicon material crucible are both arranged inside the system furnace body. The industrial camera is arranged at an oblique observation window position in the system furnace body. The industrial camera performs visual inspection of the silicon rod aperture.

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