Method for determining circle center position of wafer and wafer transfer system

Abstract

The invention discloses a wafer circle center position determination method and a wafer transfer system, and relates to the technical field of wafer calibration. The method for determining the circle center position of the wafer comprises the following steps: acquiring N wafer area images, wherein each wafer area image comprises a mark point and a part of wafer edge; based on each wafer area image, determining the position of a mark point in each wafer area image and the relative position relation between an edge point on the wafer edge and the mark point; determining the positions of N edge points on the edge of the wafer based on the position of each mark point and the relative position relationship; and determining the circle center position of the wafer according to the positions of the N edge points. According to the wafer circle center position determination method provided by the invention, the accuracy of the wafer circle center position can be improved.

Description

Technical Field

[0001] This application belongs to the technical field of wafer calibration, and particularly relates to a method for determining the center position of a wafer and a wafer transfer system. Background Art

[0002] The position accuracy of a wafer on a transfer system has a significant impact on the wafer production and yield. Therefore, the monitoring and calibration of the wafer position on the transfer system are crucial, and it is necessary to accurately obtain the center position of the wafer.

[0003] In the existing method, three marking points are manually set on the edge of the wafer, and then the center position of the wafer is determined according to the positions of the three marking points.

[0004] However, in this method, the position accuracy of the marking points is not high. The marking points may not be truly located on the edge of the wafer, and there is a certain position deviation from the wafer edge, resulting in a low accuracy of the center position of the wafer. Summary of the Invention

[0005] The embodiments of this application provide a method for determining the center position of a wafer and a wafer transfer system, which can improve the accuracy of the center position of the wafer.

[0006] On one hand, the embodiments of this application provide a method for determining the center position of a wafer. There are N marking points set on the wafer, where N is an integer not less than 3. The method includes:

[0007] Obtain N wafer area images, each of which includes a marking point and a part of the wafer edge;

[0008] Based on each wafer area image, determine the position of the marking point in each wafer area image and the relative position relationship between the edge point on the wafer edge and the marking point;

[0009] Based on each marking point position and the relative position relationship, determine the positions of N edge points on the wafer edge;

[0010] According to the positions of the N edge points, determine the center position of the wafer.

[0011] On one hand, the embodiments of this application provide a device for determining the center position of a wafer. There are N marking points set on the wafer, where N is an integer not less than 3. The device includes:

[0012] An image acquisition module, configured to obtain N wafer area images, each of which includes a marking point and a part of the wafer edge;

[0013] A position determination module, configured to determine the position of the marking point in each wafer area image and the relative position relationship between the edge point on the wafer edge and the marking point based on each wafer area image;

[0014] The position determination module is further configured to determine the positions of N edge points on the wafer edge based on the position of each marker point and the relative position relationship.

[0015] The center determination module is configured to determine the center position of the wafer according to the positions of the N edge points.

[0016] In one aspect of the embodiments of the present application, a wafer transfer system is provided, and the system includes a wafer transfer component, a motion platform, an optical imaging device, and a processor.

[0017] The wafer transfer component is configured to transfer the wafer to the motion platform.

[0018] The motion platform includes an electrostatic chuck, and the electrostatic chuck is used to adsorb the wafer.

[0019] The optical imaging device is configured to collect an image of the wafer area.

[0020] The processor is configured to execute the method for determining the center position of the wafer provided in any aspect of the embodiments of the present application as described above.

[0021] In one aspect of the embodiments of the present application, an electronic device is provided, and the device includes: a memory and a program or instruction stored on the memory and executable on the processor. When the program or instruction is executed by the processor, the method for determining the center position of the wafer provided in any aspect of the embodiments of the present application as described above is implemented.

[0022] In one aspect of the embodiments of the present application, a readable storage medium is provided, and a program or instruction is stored on the readable storage medium. When the program or instruction is executed by the processor, the method for determining the center position of the wafer provided in any aspect of the embodiments of the present application as described above is implemented.

[0023] In one aspect of the embodiments of the present application, a computer program product is provided. When the instructions in the computer program product are executed by the processor of the electronic device, the electronic device is caused to execute the method for determining the center position of the wafer provided in any aspect of the embodiments of the present application as described above.

[0024] In the method for determining the center position of the wafer provided in the embodiments of the present application, an image of the wafer area including marker points and the wafer edge is acquired. Then, according to the positions of the marker points in the wafer area image and the relative position relationship between the edge points on the wafer edge and the marker points, the positions of the edge points that are truly located on the wafer edge can be determined. In this way, in the embodiments of the present application, by collecting the wafer area image, the positions of the marker points and the relative position relationship between the edge points and the marker points are obtained, and then the positions of the edge points that are truly located on the wafer edge are obtained. Thus, the center position of the wafer can be accurately determined according to the positions of the edge points, and the accuracy of the center position of the wafer is improved. Description of the Drawings

[0025] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 is a schematic flowchart of a method for determining the center position of a wafer provided by an embodiment of the present application;

[0027] Figure 2 is a schematic diagram of an edge point provided by an embodiment of the present application;

[0028] Figure 3 is a schematic diagram of a target rectangular coordinate system provided by an embodiment of the present application;

[0029] Figure 4 is a schematic structural diagram of a wafer placed on an electrostatic chuck provided by an embodiment of the present application;

[0030] Figure 5 is a schematic structural diagram of a device for determining the center position of a wafer provided by an embodiment of the present application;

[0031] Figure 6 is a schematic structural diagram of a device for determining the center position of a wafer provided by an embodiment of the present application. Detailed Embodiments

[0032] The following will describe in detail the features and exemplary embodiments of various aspects of the present application. To make the objectives, technical solutions, and advantages of the present application clearer, the following will further describe the present application in detail in combination with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by showing examples of the present application.

[0033] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0034] It should be noted that in the technical solution of this application, the acquisition, storage, use, processing, etc. of data all comply with the relevant provisions of national laws and regulations.

[0035] It should be noted that in the embodiments of this application, some industry-existing solutions such as certain software, components, models, etc. may be mentioned. They should be regarded as exemplary, and their purpose is only to illustrate the feasibility in the implementation of the technical solution of this application, but it does not mean that the applicant has already or necessarily used this solution.

[0036] In a wafer transfer system, accurately determining the center position of a wafer is crucial for improving the wafer production rate and yield. In the prior art, the method of manually setting three marking points on the wafer edge to determine the center position has obvious defects. Due to the low position accuracy of the marking points, they may not actually be located on the wafer edge and there is a certain position deviation from the actual edge. This deviation directly results in a low accuracy of the calculated center position of the wafer, thus affecting the accuracy and efficiency of the subsequent processing process.

[0037] Exemplarily, in a typical wafer manufacturing environment, the wafer transfer system needs to process wafers with a diameter of 300 millimeters. It is required to accurately position the wafer to a specified position, and the allowable error range does not exceed ±0.1 millimeter. However, using the existing three-point marking method, since there may be a deviation of 0.2 - 0.5 millimeters between each marking point and the actual wafer edge, the error of the finally calculated center position may reach 0.3 - 0.8 millimeters. This error far exceeds the allowable range, resulting in the inability of the wafer to be accurately aligned in subsequent processes such as lithography and etching.

[0038] The purpose of the present application is to provide a method for determining the center position of a wafer and a wafer transfer system. In the method for determining the center position of a wafer provided by the embodiments of the present application, a wafer region image including marker points and the wafer edge is acquired. Then, according to the positions of the marker points in the wafer region image and the relative position relationship between the edge points on the wafer edge and the marker points, the spacing distance between the marker points and the edge points can be determined. Then, based on the spacing distance, the positions of the marker points are corrected, and the positions of the edge points that are truly located on the wafer edge can be obtained. In this way, the embodiments of the present application correct the positions of the marker points through the wafer region image to obtain the positions of the edge points that are truly located on the wafer edge. Thus, the center position of the wafer can be accurately determined according to the positions of the edge points, improving the accuracy of the center position of the wafer.

[0039] The following introduces the specific embodiments of the method for determining the center position of a wafer and the wafer transfer system provided by the embodiments of the present application. First, the method for determining the center position of a wafer is introduced below.

[0040] Figure 1 A flowchart of a method for determining the center position of a wafer is provided, where N marker points are provided on the wafer, and N is an integer not less than 3. This method for determining the center position of a wafer can be applied to the processor of a wafer transfer system, and this method for determining the center position of a wafer may include the following S101 to S104.

[0041] S101, acquire N wafer region images, and each wafer region image includes one marker point and a part of the wafer edge.

[0042] In this embodiment, a wafer refers to a circular semiconductor material wafer used for manufacturing integrated circuits, and can be specifically made of materials such as silicon and gallium arsenide; an electrostatic chuck refers to a device that adsorbs a wafer using electrostatic force, and can be specifically made of an insulating material with electrodes; a marker point refers to a feature point used for positioning on the wafer. For example, the above feature points can be formed on the wafer surface by methods such as photolithography and etching. A wafer region image refers to a local image containing marker points and a part of the wafer edge, and can be specifically acquired by a high-resolution camera or a microscope system.

[0043] As an example, first, 3 marker points are provided on the wafer. These marker points can be formed on the wafer surface by methods such as photolithography or laser etching, and appear as specific geometric shapes or patterns. Next, the wafer is placed on the electrostatic chuck of the moving platform. The electrostatic chuck firmly adsorbs the wafer on the platform surface through electrostatic force, ensuring the stability of the wafer during subsequent operations.

[0044] Then, use a high-resolution camera or microscope system to acquire images of three wafer regions. Each image contains a fiducial point and a part of the wafer edge. Finally, the processor receives the images of the three wafer regions acquired by the high-resolution camera or microscope system.

[0045] S102. Based on each wafer region image, determine the position of the fiducial point in each wafer region image and the relative position relationship between the edge points on the wafer edge and the fiducial point.

[0046] In this embodiment, a planar rectangular coordinate system is created with a preset feature point on the electrostatic chuck as the origin as the wafer coordinate system, and the fiducial point position is used to represent the coordinates of the fiducial point in this wafer coordinate system.

[0047] The edge point is any point on the wafer edge, and the relative position relationship between the edge point and the fiducial point can be at least one of the orientation of the edge point relative to the fiducial point and the relative distance between the edge point and the fiducial point.

[0048] As an example, the processor first makes the preset feature point (i.e., the origin of the wafer coordinate system) on the electrostatic chuck located at the center of the field of view of the optical imaging device, and then moves the motion platform so that the fiducial point is located at the center of the field of view of the optical imaging device. Then, according to the moving distance and moving direction of the motion platform, the coordinates of the fiducial point in the wafer coordinate system can be determined.

[0049] Then, perform image processing and recognition on the acquired wafer region images to accurately identify the relative position relationship between the edge points on the wafer edge and the fiducial point.

[0050] Specifically, the processor first preprocesses the acquired wafer region images, including Gaussian filtering for denoising and grayscale processing. Then use the Canny edge detection algorithm to identify the wafer edge, and take any point on the wafer edge as the edge point, so as to obtain the orientation of the edge point relative to the fiducial point and the relative distance between the edge point and the fiducial point.

[0051] S103. Based on each fiducial point position and the relative position relationship, determine the positions of N edge points on the wafer edge.

[0052] In this embodiment, the edge point position is used to represent the coordinates of the edge point that actually falls on the wafer edge obtained according to the fiducial point position.

[0053] As an example, the processor calculates the interval distance between the center of each fiducial point and the detected edge point according to the fiducial point position in each wafer region image and the number of interval pixel points between the fiducial point and the edge point, so as to obtain three interval distances.

[0054] Assume that the three spacing distances are 1 mm, 0.8 mm, and 1 mm respectively. The processor then moves the positions of the three marker points 1 mm, 0.8 mm, and 1 mm respectively in the direction close to the wafer edge, so as to obtain the positions of the three edge points.

[0055] S105. Determine the center position of the wafer according to the positions of the N edge points.

[0056] In some embodiments, the processor uses the least squares circle fitting algorithm to calculate the center coordinates of the wafer based on the positions of the three corrected edge points, so as to obtain the center position of the wafer.

[0057] In the method for determining the center position of the wafer provided in this embodiment, an image of the wafer area including the marker points and the wafer edge is acquired. Then, according to the positions of the marker points in the wafer area image and the relative position relationship between the edge points on the wafer edge and the marker points, the positions of the edge points that are truly located on the wafer edge can be determined. In this way, in the embodiment of the present application, by collecting the wafer area image, the positions of the marker points and the relative position relationship between the edge points and the marker points are obtained, and then the positions of the edge points that are truly located on the wafer edge are obtained. Thus, the center position of the wafer can be accurately determined according to the positions of the edge points, improving the accuracy of the center position of the wafer.

[0058] As an alternative embodiment, S102 may specifically include:

[0059] Determine the positions of the marker points in the wafer area image based on the image acquisition information of the wafer area image;

[0060] Perform filtering processing on the wafer area image to obtain a filtered wafer area image;

[0061] Perform gray-scale processing on the filtered wafer area image to obtain a gray-scale wafer area image;

[0062] Identify the relative position relationship between the edge points on the wafer edge and the marker points from the gray-scale wafer area image.

[0063] In this embodiment, the filtering processing can adopt methods such as Gaussian filtering, median filtering, or bilateral filtering to remove noise and interference in the image. For example, a 3x3 or 5x5 Gaussian filter kernel can be used to process the image to effectively reduce the high-frequency noise in the image.

[0064] The gray-scale processing can convert a color image into a gray-scale image by means of weighted average method or maximum value method. For example, the weighted average value of the RGB three channels (such as R:G:B = 0.3:0.6:0.1) can be used to calculate the gray value of each pixel. This processing can simplify the image from a three-dimensional color space to a one-dimensional gray-scale space, greatly reducing the computational amount of subsequent processing.

[0065] The image acquisition information is used to characterize the movement information of the moving platform when acquiring the image of the wafer area. Exemplarily, the image acquisition information may include the moving distance of the moving platform and the moving direction of the moving platform.

[0066] When identifying the wafer edge, an edge detection algorithm (such as the Canny algorithm) can be used to identify the wafer edge.

[0067] As an example, the processor determines the coordinates of the marking point in the wafer coordinate system according to the moving distance and moving direction of the moving platform when acquiring the wafer area image.

[0068] Then, the processor applies Gaussian filtering to the acquired wafer area image, uses a 5x5 filter kernel, and sets the standard deviation to 1.0, thereby obtaining a filtered wafer area image. This step can effectively remove high-frequency noise in the wafer area image while retaining important edge information.

[0069] Then, the weighted average method is used to convert the filtered wafer area image into a grayscale image. The specific weights can be set as R:G:B = 0.3:0.6:0.1, thereby obtaining a wafer area grayscale image. This weight assignment takes into account the sensitivity of the human eye to different colors and can improve the recognition of the image.

[0070] Finally, the Canny edge detection algorithm is applied to the wafer area grayscale image, with the low threshold set to 50 and the high threshold set to 150 to detect the wafer edge. Then the Hough transform algorithm is used to fit the circular edge, thereby obtaining the exact position of the wafer edge.

[0071] Finally, an edge point is selected on the wafer edge, thereby obtaining the relative position relationship between the edge point on the wafer edge and the marking point in the wafer area grayscale image.

[0072] Through this embodiment, the filtering process reduces the influence of image noise on subsequent recognition; grayscale conversion simplifies the image information and makes the features more prominent; and the final recognition step is performed on the optimized image, greatly improving the recognition accuracy and efficiency. In this way, the present application can accurately identify the relative position relationship between the edge point and the marking point under a complex background, significantly improving the recognition accuracy and robustness.

[0073] As an alternative embodiment, the contour of the wafer area grayscale image is a polygon, and the marking point is at the center position of the wafer area grayscale image;

[0074] Identifying the relative position relationship between the edge point on the wafer edge and the marking point from the wafer area grayscale image includes:

[0075] Determine the intersection point of any target diagonal line of the gray-scale image of the wafer area with the wafer edge as an edge point on the wafer edge, where the target diagonal line is the diagonal line that intersects the wafer edge in the gray-scale image of the wafer area;

[0076] Based on the edge point and the marking point, determine the relative positional relationship between the edge point and the marking point.

[0077] In this embodiment, the contour of the gray-scale image of the wafer area is a polygon, and there are various possible implementation methods for this design. For example, the contour can be a square, a rectangle, a hexagon, etc. The advantage of choosing a polygon contour is that it can simplify the subsequent image processing and calculation processes.

[0078] The marking point is placed at the center position of the gray-scale image of the wafer area. This layout can maximize the capture of wafer edge information while ensuring the recognizability of the marking point.

[0079] The target diagonal line is the diagonal line that passes through the wafer edge in the gray-scale image of the wafer area, and the edge point is the intersection point of the wafer edge and the target diagonal line. In this way, it can be ensured that the edge point must be located on the actual edge of the wafer.

[0080] As an example, as Figure 2 shown, a schematic diagram of an edge point is provided. Among them, the processor draws the target diagonal line 201 that passes through the wafer edge 203 in the gray-scale image of the wafer area, so as to obtain the intersection point of the target diagonal line 201 and the wafer edge 203 in the gray-scale image of the wafer area, and use it as the edge point 204. In this way, the relative positional relationship between the marking point 202 and the edge point 204 can be determined.

[0081] Through this embodiment, by introducing the edge point, the problem of possible positional deviation between the marking point and the wafer edge can be solved. By marking the target diagonal line, determine the edge point on the wafer edge, and then calculate the distance between the marking point and this edge point, so as to obtain a more accurate distance between the marking point and this edge point, and thus improve the accuracy of the edge point position.

[0082] As an alternative embodiment, the relative positional relationship includes the orientation of the edge point relative to the marking point and the relative distance between the edge point and the marking point;

[0083] From the gray-scale image of the wafer area, identify the relative positional relationship between the edge point on the wafer edge and the marking point, which may specifically include:

[0084] From the gray-scale image of the wafer area, identify the number of pixel points spaced along the target diagonal line direction between the edge point on the wafer edge and the marking point, and the orientation of the edge point relative to the marking point;

[0085] Determine the relative distance between the edge point and the marking point on the wafer edge according to the number of spaced pixel points.

[0086] In this embodiment, the number of spaced pixel points is used to characterize the pixel distance between the marking point and the edge point along the target diagonal direction. This number can be achieved by pixel counting along the target diagonal.

[0087] The relative distance is used to characterize the distance of relative offset between the edge point and the marking point. For example, if the offset between the marking point and the edge point is 5 units, then the relative distance between the marking point and the edge point is 5 units.

[0088] The orientation of the edge point relative to the marking point is used to characterize the direction of relative offset between the marking point and the edge point. For example, the edge point can be on the positive half-axis of the X-axis in the plane rectangular coordinate system constructed with the marking point as the origin. According to the orientation of the edge point relative to the marking point, it can be determined whether to add or subtract the offset distance.

[0089] The orientation of the edge point relative to the marking point The orientation of the edge point relative to the marking point The orientation of the edge point relative to the marking point As an alternative embodiment, as Figure 2 shown, the processor first identifies the marking point 202 and the edge point 204 from the gray-scale image of the wafer area, so that the number of spaced pixel points between the marking point 202 and the edge point 204 along the target diagonal direction can be obtained, which can be achieved by pixel counting; at the same time, the orientation of the edge point 204 relative to the marking point 202 can also be obtained.

[0090] Then, according to the number of spaced pixel points and the size of each pixel point, the relative distance between the marking point 202 and the wafer edge 203 can be obtained.

[0091] Through this embodiment, according to the gray-scale image of the wafer area, the orientation of the edge point on the wafer edge relative to the marking point and the relative distance between the edge point and the marking point can be accurately identified. Thus, it helps to accurately calculate the position of the edge point on the wafer edge according to the orientation of the edge point relative to the marking point and the relative distance between the edge point and the marking point. In this way, the accuracy of the edge point position is greatly improved, and thus the determination accuracy of the wafer center position is improved.

[0092] As an alternative embodiment, the relative distance includes the relative distance in the first coordinate axis direction and the relative distance in the second coordinate axis direction;

[0093] Determine the relative distance between the edge point and the marking point on the wafer edge according to the number of spaced pixel points, which may specifically include:

[0094] Multiply the number of spaced pixel points by the size of the pixel point of the wafer area image to obtain the straight-line distance between the edge point and the marking point on the wafer edge;

[0095] Based on the first coordinate axis coefficient and the straight-line distance, determine the relative distance between the edge point on the wafer edge and the marking point in the direction of the first coordinate axis;

[0096] Based on the second coordinate axis coefficient and the straight-line distance, determine the relative distance between the edge point on the wafer edge and the marking point in the direction of the second coordinate axis.

[0097] In this embodiment, the pixel size is used to convert the pixel distance into the actual physical distance. The pixel size is usually determined by the parameters of the image acquisition device, and an accurate value can be obtained through the calibration process.

[0098] The first coordinate axis coefficient and the second coordinate axis coefficient are respectively used to determine the relative distance between the edge point on the wafer edge and the marking point in the direction of the first coordinate axis, and the relative distance between the edge point on the wafer edge and the marking point in the direction of the second coordinate axis.

[0099] Exemplarily, the direction of the first coordinate axis can be the X-axis direction, then the first coordinate axis coefficient is used to determine the relative distance in the X-axis direction; the direction of the second coordinate axis can be the Y-axis direction, then the second correction coefficient is used to determine the relative distance in the Y-axis direction.

[0100] As an example, as Figure 2 shown, the processor first calculates the number of spaced pixel points of the marking point 202 and the edge point 204 on the target diagonal line 201. Then, multiply the number of spaced pixel points by the pixel size to obtain the straight-line distance between the marking point 202 and the wafer edge 203.

[0101] Then, based on the first coordinate axis coefficient and the straight-line distance, obtain the relative distance between the edge point and the marking point in the direction of the first coordinate axis; based on the second coordinate axis coefficient and the straight-line distance, obtain the relative distance between the edge point and the marking point in the direction of the second coordinate axis. Exemplarily, assume that the coordinate of a certain marking point is (100, 100), the calculated straight-line distance between the edge point and the marking point is 10 units, the first correction coefficient is 1.05, and the second correction coefficient is 0.95. Then, the relative distance in the direction of the first coordinate axis is 10 * 1.05 = 10.5 units, and the relative distance in the direction of the second coordinate axis is 10 * 0.95 = 9.5 units.

[0102] Through this embodiment, by introducing the first coordinate axis coefficient and the second coordinate axis coefficient, the deviation between the marking point and the wafer edge can be effectively compensated. In this way, the accuracy of the edge point position is greatly improved, thereby improving the determination accuracy of the wafer center position.

[0103] As an optional embodiment, S103 may specifically include:

[0104] Taking the marked point as the origin of the coordinate system, a target rectangular coordinate system is constructed;

[0105] According to the position of the marked point, the quadrant in which the edge point is located in the target rectangular coordinate system, the relative distance in the first coordinate axis direction and the relative distance in the second coordinate axis direction between the edge point and the marked point, the position of the edge point on the wafer edge is determined.

[0106] In this embodiment, taking the marked point as the origin of the coordinate system, a plane rectangular coordinate system is constructed as the target rectangular coordinate system. It can provide a reference coordinate system for the subsequent determination of the edge point position, making the determination process of the edge point position more accurate and controllable.

[0107] Secondly, according to the quadrant in which the edge point is located in the target rectangular coordinate system, using the relative distance in the first coordinate axis direction and the relative distance in the second coordinate axis direction, the position of the edge point is determined. This step specifically considers the specific position of the edge point in the coordinate system, and through the determination methods of different quadrants, the accuracy of the edge point position is ensured.

[0108] Specifically, for the step of determining the edge point position according to the quadrant in which the edge point is located in the target rectangular coordinate system, different determination strategies can be adopted. For example, when the edge point is located in the first quadrant, the relative distance in the first coordinate axis direction can be added to the X coordinate of the marked point, and the relative distance in the second coordinate axis direction can be added to the Y coordinate of the marked point; while when the edge point is located in the second quadrant, the relative distance in the first coordinate axis direction can be subtracted from the X coordinate of the marked point, and the relative distance in the second coordinate axis direction can be added to the Y coordinate of the marked point. Similarly, corresponding determination strategies can be adopted according to different quadrants where the edge point is located.

[0109] As Figure 3 shown, a schematic diagram of a target rectangular coordinate system is provided. Among them, taking the marked point 202 as the origin of the coordinate system, a target rectangular coordinate system is constructed. As can be seen from the figure, the edge point 204 is located in the first quadrant. Therefore, at this time, the relative distance in the first coordinate axis direction is added to the X coordinate of the marked point 202, and the relative distance in the second coordinate axis direction is added to the Y coordinate of the marked point 202, thereby obtaining the position of the edge point.

[0110] Through this embodiment, by constructing a coordinate system and considering the quadrant of the edge point, the position of the edge point can be determined more accurately, thereby improving the determination accuracy of the center position of the wafer. In this way, the determination error of the center position of the wafer caused by inaccurate position of the marked point can be effectively reduced, thereby improving the determination accuracy of the center position of the wafer.

[0111] As an alternative embodiment, the position of the edge point on the wafer is determined according to the position of the marking point, the quadrant in the target rectangular coordinate system where the edge point is located, the relative distance in the first coordinate axis direction and the relative distance in the second coordinate axis direction between the edge point and the marking point. Specifically, it may include:

[0112] When the edge point is in the first quadrant of the target rectangular coordinate system, the position of the edge point on the wafer is determined by the following formula 1:

[0113] W = (X + A1D, Y + A2D) Formula 1

[0114] When the edge point is in the second quadrant of the target rectangular coordinate system, the position of the edge point on the wafer is determined by the following formula 2:

[0115] W = (X - A1D, Y + A2D) Formula 2

[0116] When the edge point is in the third quadrant of the target rectangular coordinate system, the position of the edge point on the wafer is determined by the following formula 3:

[0117] W = (X - A1D, Y - A2D) Formula 3

[0118] When the edge point is in the fourth quadrant of the target rectangular coordinate system, the position of the edge point on the wafer is determined by the following formula 4:

[0119] W = (X + A1D, Y - A2D) Formula 4

[0120] In the formula, W is used to represent the position of the edge point, X is used to represent the coordinate of the marking point in the first coordinate axis direction, Y is used to represent the coordinate of the marking point in the second coordinate axis direction, A1 is used to represent the first coordinate axis coefficient, A2 is used to represent the second coordinate axis coefficient, and D is used to represent the straight-line distance between the edge point and the marking point.

[0121] In this embodiment, a target rectangular coordinate system with the marking point as the origin is constructed to accurately locate the orientation of the edge point relative to the marking point. According to the quadrant where the edge point is located, the corresponding formula is selected, and using the marking point coordinates, the coordinate axis coefficients, and the straight-line distance between the edge point and the marking point, the accurate position of the edge point on the wafer is calculated.

[0122] Among them, the first coordinate axis coefficient and the second coordinate axis coefficient are determined according to the included angle formed by the coordinate axis of the target rectangular coordinate system and the connection line between the marking point and the edge point. As Figure 3 shown, when the connection line between the marking point and the edge point is the target diagonal line, at this time, the included angle formed by the coordinate axis of the target rectangular coordinate system and the target diagonal line is 45 degrees. At this time, the first coordinate axis coefficient is cos45°, and the second coordinate axis coefficient is sin45°.

[0123] In this embodiment, according to the quadrant where the edge point is located, the corresponding formula is selected, and the accurate edge point position on the wafer edge is calculated by using the coordinates of the marking points, the coefficients of the coordinate axes, and the straight-line distance between the edge point and the marking points. In this way, the edge points on the wafer edge are associated with the marking points, and the situations of different quadrants are considered, so that the edge point position can be accurately calculated and the accuracy of the edge point position can be improved.

[0124] As an alternative embodiment, after S105, the method for determining the center position of the wafer may further include:

[0125] Comparing the center position of the wafer with a reference position to obtain a position deviation value;

[0126] Performing position calibration on the wafer according to the position deviation value.

[0127] In this embodiment, the reference position is used to represent the ideal position in the wafer coordinate system corresponding to the center of the wafer set in advance.

[0128] The position deviation value is obtained by comparing the center position of the wafer with the reference position. This comparison process can adopt various algorithms. For example, the differences between the two positions on the X-axis and Y-axis can be calculated, or the Euclidean distance between the two points can be calculated.

[0129] The position calibration is performed according to the position deviation value. There can be various calibration methods. For example, a stepping motor can be used to precisely adjust the position of the wafer, or the adsorption force distribution of the electrostatic chuck can be adjusted to finely adjust the position of the wafer. The calibration process can be a one-time process or an iterative process until the position deviation value is less than a preset threshold.

[0130] As an example, after obtaining the center position of the wafer, the processor compares the center position of the wafer with the reference position to respectively obtain the position deviation value in the X-axis direction and the position deviation value in the Y-axis direction.

[0131] Then, the processor controls the motion platform to move according to the position deviation value in the X-axis direction and the position deviation value in the Y-axis direction, so as to complete the position calibration of the wafer.

[0132] In this embodiment, by adding a position calibration step after determining the center position of the wafer, the problem of position calibration after determining the center position of the wafer is solved. In this way, not only the center position of the wafer is determined, but also the position accuracy of the wafer on the wafer transfer system is further improved by comparing with the reference position and calibration.

[0133] Based on the method for determining the center position of the wafer. Correspondingly, the present application also provides a specific embodiment of a wafer transfer system.

[0134] The wafer transfer system provided by the embodiments of the present application specifically includes a wafer transfer component, a motion platform, an optical imaging device, and a processor;

[0135] The wafer transfer component is used to transfer the wafer to the motion platform;

[0136] The motion platform includes an electrostatic chuck, and the electrostatic chuck is used to adsorb the wafer;

[0137] The optical imaging device is used to collect images of the wafer area;

[0138] The processor is used to execute the method for determining the center position of the wafer as described in any one of the above.

[0139] In this embodiment, the wafer transfer component is a component for transferring the wafer. Exemplarily, the wafer transfer component can be a manipulator.

[0140] The optical imaging device is a device for obtaining optical images. Exemplarily, the optical imaging device can be an optical microscope.

[0141] As an example, as Figure 4 shown, a schematic structural diagram of a wafer placed on an electrostatic chuck is provided.

[0142] Among them, the motion platform 410 includes an electrostatic chuck 420. The wafer transfer component transfers the wafer 430 to the electrostatic chuck 430, and the electrostatic chuck 420 generates an adsorption force on the wafer 430 to fix the position of the wafer 430 and keep it unchanged.

[0143] Then, there is an optical imaging device 440 above the stage 410. The optical imaging device 440 collects multiple images of the wafer area corresponding to the wafer 430 on the electrostatic chuck 420. Finally, the processor executes the method for determining the center position of the wafer according to the multiple images of the wafer area obtained by the optical imaging device 440.

[0144] Based on the method for determining the center position of the wafer. Correspondingly, the embodiments of the present application also provide specific embodiments of a device for determining the center position of the wafer.

[0145] As Figure 5 shown, the device 500 for determining the center position of the wafer provided by the embodiments of the present application includes an image acquisition module 510, a position determination module 520, and a center determination module 530.

[0146] The image acquisition module 510 is used to acquire N images of the wafer area, and each image of the wafer area includes a marked point and a part of the wafer edge;

[0147] A position determination module 520, configured to determine the positions of the marker points in each wafer region image and the relative position relationship between the edge points on the wafer edge and the marker points based on each wafer region image;

[0148] The position determination module 520 is further configured to determine the positions of N edge points on the wafer edge based on each marker point position and the relative position relationship;

[0149] A center determination module 540, configured to determine the center position of the wafer according to the positions of the N edge points.

[0150] As an alternative embodiment, the position determination module 520 specifically includes the following units:

[0151] A position determination unit, configured to determine the position of the marker point in the wafer region image based on the image acquisition information of the wafer region image;

[0152] An image filtering unit, configured to perform filtering processing on the wafer region image to obtain a wafer region filtered image;

[0153] An image grayscaling unit, configured to perform grayscaling processing on the wafer region filtered image to obtain a wafer region grayscale image;

[0154] An image recognition unit, configured to recognize the relative position relationship between the edge points on the wafer edge and the marker points from the wafer region grayscale image.

[0155] As an alternative embodiment, the contour of the wafer region grayscale image is a polygon, and the marker point is at the center position of the wafer region grayscale image;

[0156] The image recognition unit is specifically configured to:

[0157] Determine the intersection point of any target diagonal line of the wafer region grayscale image and the wafer edge as the edge point on the wafer edge, where the target diagonal line is the diagonal line that intersects the wafer edge in the wafer region grayscale image;

[0158] Determine the relative position relationship between the edge point and the marker point based on the edge point and the marker point.

[0159] As an alternative embodiment, the relative position relationship includes the orientation of the edge point relative to the marker point and the relative distance between the edge point and the marker point;

[0160] The image recognition unit specifically includes the following sub-units:

[0161] A pixel point recognition sub-unit, configured to recognize the number of spaced pixel points between the edge points on the wafer edge and the marker points along the target diagonal line direction and the orientation of the edge point relative to the marker point from the wafer region grayscale image;

[0162] A relative distance determination subunit, configured to determine the relative distance between an edge point on the wafer edge and a marking point according to the number of spaced pixel points.

[0163] As an alternative embodiment, the relative distance includes the relative distance in the first coordinate axis direction and the relative distance in the second coordinate axis direction;

[0164] The relative distance determination subunit is specifically configured to:

[0165] Multiply the number of spaced pixel points by the pixel size of the wafer area image to obtain the straight-line distance between the edge point on the wafer edge and the marking point;

[0166] Based on the first coordinate axis coefficient and the straight-line distance, determine the relative distance between the edge point on the wafer edge and the marking point in the first coordinate axis direction;

[0167] Based on the second coordinate axis coefficient and the straight-line distance, determine the relative distance between the edge point on the wafer edge and the marking point in the second coordinate axis direction.

[0168] As an alternative embodiment, the position determination module 520 further includes the following units:

[0169] A coordinate system construction unit, configured to construct a target rectangular coordinate system with the marking point as the origin of the coordinate system;

[0170] The position determination unit is further configured to determine the position of the edge point on the wafer edge according to the marking point position, the quadrant where the edge point is located in the target rectangular coordinate system, the relative distance between the edge point and the marking point in the first coordinate axis direction, and the relative distance between the edge point and the marking point in the second coordinate axis direction.

[0171] As an alternative embodiment, the position determination unit is specifically configured to:

[0172] When the edge point is in the first quadrant of the target rectangular coordinate system, determine the position of the edge point on the wafer edge through the following formula:

[0173] W = (X + A1D, Y + A2D)

[0174] When the edge point is in the second quadrant of the target rectangular coordinate system, determine the position of the edge point on the wafer edge through the following formula:

[0175] W = (X - A1D, Y + A2D)

[0176] When the edge point is in the third quadrant of the target rectangular coordinate system, determine the position of the edge point on the wafer edge through the following formula:

[0177] W = (X - A1D, Y - A2D)

[0178] When the edge point is in the fourth quadrant of the target rectangular coordinate system, the position of the edge point on the wafer is determined by the following formula:

[0179] W = (X + A1D, Y - A2D)

[0180] In the formula, W is used to represent the position of the edge point, X is used to represent the coordinate of the marked point in the first coordinate axis direction, Y is used to represent the coordinate of the marked point in the second coordinate axis direction, A1 is used to represent the first coordinate axis coefficient, A2 is used to represent the second coordinate axis coefficient, and D is used to represent the straight-line distance between the edge point and the marked point.

[0181] As an alternative embodiment, after determining the center position of the wafer according to the positions of N edge points, the apparatus 200 for determining the center position of the wafer further includes the following modules:

[0182] A position comparison module, configured to compare the center position of the wafer with a reference position to obtain a position deviation value;

[0183] A position calibration module, configured to perform position calibration on the wafer according to the position deviation value.

[0184] Based on the method for determining the center position of the wafer. Correspondingly, the present application also provides a specific embodiment of an apparatus for determining the center position of the wafer.

[0185] Figure 6 FIG. shows a schematic hardware structure diagram of an apparatus for determining the center position of the wafer provided by an embodiment of the present application.

[0186] The apparatus for determining the center position of the wafer may include a processor 601 and a memory 602 storing computer program instructions.

[0187] Specifically, the above-mentioned processor 601 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0188] The memory 602 may include a mass storage for data or instructions. By way of example and not limitation, the memory 602 may include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive, or a combination of two or more of these. In a suitable case, the memory 602 may include removable or non-removable (or fixed) media. In a suitable case, the memory 602 may be inside or outside the integrated gateway disaster recovery device. In a specific embodiment, the memory 602 is a non-volatile solid-state memory.

[0189] The processor 601 reads and executes the computer program instructions stored in the memory 602 to implement any one of the methods for determining the center position of the wafer in the above embodiments.

[0190] In one example, the device for determining the center position of the wafer may further include a communication interface 603 and a bus 610. Among them, as Figure 6 shown, the processor 601, the memory 602, and the communication interface 603 are connected through the bus 610 to complete communication with each other.

[0191] The communication interface 603 is mainly used to implement communication between the various modules, devices, units, and / or devices in the embodiments of the present application.

[0192] The bus 610 includes hardware, software, or both, and couples the components of the device for determining the center position of the wafer to each other. By way of example and not limitation, the bus may include an accelerated graphics port (AGP) or other graphics bus, an enhanced industry standard architecture (EISA) bus, a front-side bus (FSB), a hyperTransport (HT) interconnect, an industry standard architecture (ISA) bus, an InfiniBand interconnect, a low-pin count (LPC) bus, a memory bus, a micro-channel architecture (MCA) bus, a peripheral component interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a serial advanced technology attachment (SATA) bus, a video electronics standards association local (VLB) bus, or other suitable buses, or a combination of two or more of these. In a suitable case, the bus 610 may include one or more buses. Although the embodiments of the present application describe and illustrate specific buses, the present application contemplates any suitable bus or interconnect.

[0193] In addition, in combination with the method for determining the center position of the wafer in the above embodiments, the embodiments of the present application may provide a computer storage medium to implement. Computer program instructions are stored on the computer storage medium; when the computer program instructions are executed by the processor, any one of the methods for determining the center position of the wafer in the above embodiments is implemented.

[0194] In addition, in combination with the method for determining the center position of the wafer in the above embodiments, the embodiments of the present application can be implemented by providing a computer program product. When the instructions in the computer program product are executed by the processor of the electronic device, the electronic device is caused to execute the method for determining the center position of the wafer provided in any aspect of the above embodiments of the present application.

[0195] It should be clear that the present application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, the detailed description of known methods is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order between steps after understanding the spirit of the present application.

[0196] The functional blocks shown in the above block diagrams can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application-specific integrated circuit (ASIC), appropriate firmware, a plug-in, a functional card, and so on. When implemented in software, the elements of the present application are programs or code segments used to perform the required tasks. The program or code segment can be stored in a machine-readable medium or transmitted via a data signal carried in a carrier wave on a transmission medium or a communication link. A "machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical discs, hard disks, fiber optic media, radio frequency (RF) links, and so on. The code segment can be downloaded via a computer network such as the Internet, an intranet, and so on.

[0197] It should also be noted that the exemplary embodiments mentioned in the present application describe some methods or systems based on a series of steps or devices. However, the present application is not limited to the order of the above steps, that is, the steps can be executed in the order mentioned in the embodiments, can be different from the order in the embodiments, or several steps can be executed simultaneously.

[0198] As described above with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present disclosure. It should be understood that each block in the flowchart and / or block diagram, and the combination of blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing device enable the implementation of the functions / actions specified in one or more blocks of the flowchart and / or block diagram. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field programmable logic circuit. It should also be understood that each block in the block diagram and / or flowchart, and the combination of blocks in the block diagram and / or flowchart, can also be implemented by dedicated hardware that performs the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0199] As described above, the foregoing is only a specific implementation manner of the present application. Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, modules, and units described above can refer to the corresponding processes in the foregoing method embodiments, and will not be described herein again. It should be understood that the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present application can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered by the protection scope of the present application.

Claims

1. A method for determining the center position of a wafer, characterized in that: The wafer is provided with N marking points, where N is an integer not less than 3; the method comprises: Acquire N wafer area images, each of the wafer area images including one of the marking points and a portion of the wafer edge; Based on each of the wafer area images, determining the position of the marking point in each of the wafer area images and the relative position relationship between the edge point on the edge of the wafer and the marking point; Based on the position of each of the marking points and the relative position relationship, determining the positions of N edge points on the edge of the wafer; The center position of the wafer is determined according to the N edge point positions.

2. The method according to claim 1, characterized in that: The determining, based on each of the wafer area images, the position of the marking point in each of the wafer area images and the relative position relationship between the edge point on the wafer edge and the marking point comprises: Based on the image acquisition information of the wafer area image, determining the position of the marking point in the wafer area image; Performing filtering processing on the wafer area image to obtain a wafer area filtering image; Gray-scaling the wafer region filter image to obtain a wafer region gray-scale image; The relative position relationship between the edge point on the wafer edge and the marking point is identified from the wafer area grayscale image.

3. The method according to claim 2, characterized in that The outline of the wafer area grayscale image is a polygon, and the marking point is located at the center of the wafer area grayscale image; The step of identifying the relative position relationship between the edge point on the edge of the wafer and the marking point from the wafer region grayscale image includes: Determine the intersection of any target diagonal line of the wafer region grayscale image and the wafer edge as an edge point on the wafer edge, wherein the target diagonal line is a diagonal line in the wafer region grayscale image that intersects with the wafer edge; Based on the edge point and the marking point, a relative position relationship between the edge point and the marking point is determined.

4. The method according to claim 2, characterized in that: The relative position relationship includes the orientation of the edge point relative to the marking point and the relative distance between the edge point and the marking point; The step of identifying the relative position relationship between the edge point on the edge of the wafer and the marking point from the wafer region grayscale image includes: From the wafer region grayscale image, identify the number of pixel points between the edge point on the wafer edge and the marking point along the target diagonal direction, and the orientation of the edge point relative to the marking point; The relative distance between the edge point on the edge of the wafer and the marking point is determined according to the number of the spaced pixel points.

5. The method according to claim 4, characterized in that The relative distance includes a relative distance in the direction of the first coordinate axis and a relative distance in the direction of the second coordinate axis; Determining the relative distance between the edge point on the edge of the wafer and the marking point according to the number of the spaced pixel points includes: Multiplying the number of the spaced pixels by the pixel size of the wafer area image to obtain a straight-line distance between an edge point on the wafer edge and the marking point; Determine the relative distance between the edge point on the edge of the wafer and the marking point in the direction of the first coordinate axis based on the first coordinate axis coefficient and the straight-line distance; Based on the second coordinate axis coefficient and the straight-line distance, a relative distance between an edge point on the wafer edge and the marking point in the direction of the second coordinate axis is determined.

6. The method according to any one of claims 1 to 5, characterized in that: The determining of the N edge point positions on the edge of the wafer based on the position of each of the marking points and the relative position relationship includes: Taking the marked point as the origin of the coordinate system, constructing a target rectangular coordinate system; The edge point position on the wafer edge is determined according to the marking point position, the quadrant of the target rectangular coordinate system in which the edge point is located, the relative distance between the edge point and the marking point in the first coordinate axis direction and the relative distance in the second coordinate axis direction.

7. The method according to claim 6, characterized in that The step of determining the edge point position on the edge of the wafer according to the position of the marking point, the quadrant in which the edge point is located in the target rectangular coordinate system, and the relative distance between the edge point and the marking point in the direction of the first coordinate axis and the relative distance between the edge point and the marking point in the direction of the second coordinate axis includes: In the case where the edge point is located in the first quadrant of the target rectangular coordinate system, the position of the edge point on the edge of the wafer is determined by the following formula: W=(X+A1D,Y+A2D) In the case where the edge point is located in the second quadrant of the target rectangular coordinate system, the position of the edge point on the edge of the wafer is determined by the following formula: W=(X-A1D,Y+A2D) In the case where the edge point is located in the third quadrant of the target rectangular coordinate system, the position of the edge point on the edge of the wafer is determined by the following formula: W=(X-A1D,Y-A2D) In the case where the edge point is located in the fourth quadrant of the target rectangular coordinate system, the position of the edge point on the edge of the wafer is determined by the following formula: W=(X+A1D,Y-A2D) Wherein, W is used to characterize the position of the edge point, X is used to characterize the coordinate of the marking point in the direction of the first coordinate axis, Y is used to characterize the coordinate of the marking point in the direction of the second coordinate axis, A1 is used to characterize the first coordinate axis coefficient, A2 is used to characterize the second coordinate axis coefficient, and D is used to characterize the straight-line distance between the edge point and the marking point.

8. A wafer transfer system, characterized in that: The wafer conveying system includes a wafer conveying component, a motion platform, an optical imaging device and a processor; The wafer transfer assembly is used to transfer the wafer to the motion platform; The motion platform includes an electrostatic chuck, and the electrostatic chuck is used to adsorb the wafer; The optical imaging device is used to collect wafer area images; The processor is used to execute the method for determining the center position of a wafer as described in any one of claims 1-7.

9. An electronic device, characterized in that: The device comprises: a processor and a memory storing computer program instructions; When the processor executes the computer program instructions, the method for determining the center position of a wafer as described in any one of claims 1-7 is implemented.

10. A computer program product, characterized in that When the instructions in the computer program product are executed by a processor of an electronic device, the electronic device executes the method for determining the center position of a wafer as described in any one of claims 1 to 7.

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