Method for calibrating relative position of alignment camera and measurement camera and related device

Abstract

The invention discloses a relative position calibration method for an alignment camera and a measurement camera and a related device, and relates to the technical field of chip manufacturing. A calibration plate image comprising two right-angle sides is selected, and angular points of the two right-angle sides are used as calibration target points; the method comprises the following steps: firstly, acquiring a first angular point coordinate of an angular point in a first calibration plate image under an alignment camera, then acquiring a second angular point coordinate of the angular point in a second calibration plate image under a measurement camera, and finally, obtaining a relative position relationship between the alignment camera and the measurement camera through coordinate conversion. The calibration plate image comprises two right-angle sides, has positioning characteristics in the horizontal direction and the vertical direction, has direction uniqueness, and can be imaged under the alignment camera and the measurement camera at the same time, so that the relative position calibration of the alignment camera and the measurement camera can be accurately realized.

Description

Technical Field

[0001] The present application relates to the field of chip manufacturing technology, and in particular to a relative position calibration method for an alignment camera and a measurement camera and a related device. Background Art

[0002] Chips are the core and cornerstone of high-end manufacturing, and determine the development of high-tech industries. Photolithography is an extremely critical part of the chip manufacturing process. The process level of photolithography directly determines the process and performance of the chip. Chips are made up of multiple layers of circuits, and the manufacture of a chip often requires dozens of photolithography to complete. The alignment deviation between adjacent circuit layers in the chip is also called overlay error. The rapid measurement and accurate evaluation of overlay error is the key to optimizing the operating parameters of the lithography machine and managing the process yield.

[0003] After the lithography machine performs lithography, there will be a certain amount of overlay deviation. If the overlay deviation is to be accurately measured, the wafer must first be centered and leveled under the alignment camera, and then the wafer coordinate system under the alignment camera must be established. Then, according to the positional relationship between the alignment camera and the measurement camera, the wafer coordinate system under the alignment camera is mapped to the measurement camera, so that the target point to be measured can be accurately found for measurement. It can be seen that the calibration accuracy of the relative position relationship between the alignment camera and the measurement camera affects the accuracy of finding the target mark under the measurement camera, thereby affecting the measurement accuracy of the overlay deviation. Summary of the invention

[0004] In view of the above problems, the present application provides a relative position calibration method and related device for an alignment camera and a measurement camera, which can accurately realize the relative position calibration of the alignment camera and the measurement camera. The specific scheme is as follows:

[0005] The first aspect of the present application provides a relative position calibration method for an alignment camera and a measurement camera, comprising:

[0006] Move the alignment camera to a first preset position to acquire a first calibration plate image, wherein the first preset position corresponds to the position coordinates of the alignment camera in the workbench coordinate system, and the first calibration plate image includes a corner point formed by two right-angled sides;

[0007] Move the measurement camera to a second preset position to obtain a second calibration plate image, wherein the second preset position corresponds to the position coordinates of the measurement camera in the workbench coordinate system, and the second calibration plate image includes the corner point;

[0008] Determine the first corner point coordinates of the corner point in the first calibration plate image, and determine the second corner point coordinates of the corner point in the second calibration plate image;

[0009] Position calibration information between the alignment camera and the measurement camera is determined by using the matching relationship between the first corner point coordinates and the second corner point coordinates.

[0010] In a possible implementation, determining the position calibration information between the alignment camera and the measurement camera by using the matching relationship between the first corner point coordinates and the second corner point coordinates includes:

[0011] Determine the coordinates of the first corner point and the

[0012] A first calculation relationship among the central pixel coordinates of the first calibration plate image, the pre-calibrated pixel equivalent under the alignment camera, the position coordinates of the alignment camera in the workbench coordinate system, and the physical coordinates of the corner point under the alignment camera;

[0013] Determine a second calculation relationship between the coordinates of the second corner point and the central pixel coordinates of the second calibration plate image, the pre-calibrated pixel equivalent of the measurement camera, the position coordinates of the measurement camera in the workbench coordinate system, and the physical coordinates of the corner point in the measurement camera;

[0014] The physical coordinates of the corner point under the alignment camera are made equal to the physical coordinates of the corner point under the measurement camera, and the relative positions of the alignment camera and the measurement camera are determined according to the first calculation relationship and the second calculation relationship.

[0015] In a possible implementation, determining a first corner point coordinate of the corner point in the first calibration plate image, and determining a second corner point coordinate of the corner point in the second calibration plate image includes:

[0016] The following operations are performed respectively for the calibration plate images acquired by the alignment camera and the measurement camera:

[0017] Performing edge detection on the calibration plate image, and determining the position of the corner point area in the calibration plate image according to the edge detection result;

[0018] Performing tilt correction on the calibration plate image to obtain a target calibration plate image, wherein two right-angled sides of the corner point in the target calibration plate image are respectively in the horizontal direction and the vertical direction;

[0019] Determine the pixel coordinates of the corner points in the target calibration plate image;

[0020] Determining the pixel coordinates of the corner points in the calibration plate image according to the inclination angle of the right-angled side in the calibration plate image and the pixel coordinates of the corner points in the target calibration plate image;

[0021] The pixel coordinates of the corner points in the first calibration plate image are the first corner point coordinates, and the pixel coordinates of the corner points in the second calibration plate image are the second corner point coordinates.

[0022] In a possible implementation, performing edge detection on the calibration plate image and determining the position of the corner point region in the calibration plate image according to the edge detection result includes:

[0023] Perform edge detection on the calibration plate image to obtain the edge area;

[0024] Performing an opening operation on the edge region in the horizontal direction, removing the noise region in the vertical direction, and obtaining a horizontal region;

[0025] Performing an opening operation on the edge region in the vertical direction, removing the noise region in the horizontal direction, and obtaining a vertical region;

[0026] An intersection of the horizontal area and the vertical area is determined as the corner point area.

[0027] In a possible implementation, performing tilt correction on the calibration plate image to obtain a target calibration plate image includes:

[0028] Generate a rectangular frame of a preset size in the corner point area, and calculate the grayscale mean in the rectangular frame;

[0029] Using the grayscale mean as a threshold, binarizing the image in the rectangular frame to obtain a foreground area and a background area;

[0030] Calculating grayscale means of the foreground area and the background area respectively;

[0031] Generate a corner point standard template image according to the grayscale mean of the foreground area and the background area;

[0032] Perform template matching on the corner point standard template image and the calibration plate image to calculate the inclination angle of the right-angle side in the calibration plate image;

[0033] The calibration plate image is tilt-corrected according to the tilt angle to obtain the target calibration plate image.

[0034] In a possible implementation, determining pixel coordinates of corner points in the target calibration plate image includes:

[0035] Performing grayscale projection on the image in the horizontal direction and the vertical direction in the region of interest of the corner point in the target calibration plate image, respectively, to obtain grayscale curves in the horizontal direction and the vertical direction;

[0036] Calculate the gradient curves corresponding to the grayscale curves in the horizontal and vertical directions respectively, and determine the position with the largest gradient as the edge position;

[0037] The pixel coordinates of the corner points in the target calibration plate image are determined according to the edge positions in the horizontal direction and the vertical direction.

[0038] A second aspect of the present application provides a relative position calibration device for an alignment camera and a measurement camera, comprising:

[0039] A first image acquisition unit, used for moving the alignment camera to a first preset position to acquire a first calibration plate image, wherein the first preset position corresponds to the position coordinates of the alignment camera in the workbench coordinate system, and the first calibration plate image includes a corner point formed by two right-angled sides;

[0040] A second image acquisition unit, used for moving the measurement camera to a second preset position to acquire a second calibration plate image, wherein the second preset position corresponds to the position coordinates of the measurement camera in the workbench coordinate system, and the second calibration plate image includes the corner point;

[0041] a coordinate determination unit, configured to determine a first corner point coordinate of the corner point in the first calibration plate image, and determine a second corner point coordinate of the corner point in the second calibration plate image;

[0042] A calibration unit is used to determine position calibration information between the alignment camera and the measurement camera by using the matching relationship between the first corner point coordinates and the second corner point coordinates.

[0043] A third aspect of the present application provides an electronic device, comprising at least one processor and a memory connected to the processor, wherein:

[0044] The memory is used to store computer programs;

[0045] The processor is used to execute the computer program so that the electronic device can implement the relative position calibration method of the alignment camera and the measurement camera according to the first aspect or any implementation manner of the first aspect.

[0046] A fourth aspect of the present application provides a computer program product, comprising computer-readable instructions. When the computer-readable instructions are executed on an electronic device, the electronic device implements the relative position calibration method of the alignment camera and the measurement camera according to the first aspect or any implementation of the first aspect.

[0047] A fifth aspect of the present application provides a computer storage medium, which carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can use the relative position calibration method of the alignment camera and the measurement camera of the above-mentioned first aspect or any implementation of the first aspect.

[0048] By means of the above technical solution, the present application provides a relative position calibration method and related device for an alignment camera and a measurement camera, wherein a calibration plate image including two right-angled sides is selected, and the corner points of the two right-angled sides are used as calibration target points. First, the coordinates of the first corner point in the first calibration plate image under the alignment camera are obtained, and then the coordinates of the second corner point in the second calibration plate image under the measurement camera are obtained, and finally the relative position relationship between the alignment camera and the measurement camera is obtained by coordinate conversion. Since the calibration plate image includes two right-angled sides, has positioning features in the horizontal and vertical directions, has directional uniqueness, and can be imaged under the alignment camera and the measurement camera at the same time, it can accurately realize the relative position calibration of the alignment camera and the measurement camera. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0050] Figure 1 A schematic diagram of a calibration pattern provided for this application;

[0051] Figure 2 Another schematic diagram of a calibration pattern provided for this application;

[0052] Figure 3 A schematic diagram of a flow chart of a relative position calibration method of an alignment camera and a measurement camera provided in an embodiment of the present application;

[0053] Figure 4 A schematic diagram of a calibration pattern provided in an embodiment of the present application;

[0054] Figure 5 An example diagram of a first calibration plate image obtained by aligning a camera according to an embodiment of the present application;

[0055] Figure 6 An example diagram of a second calibration plate image obtained by aligning the camera provided in an embodiment of the present application;

[0056] Figure 7 A schematic diagram of an edge strength image provided in an embodiment of the present application;

[0057] Figure 8A schematic diagram of a binarized edge region provided in an embodiment of the present application;

[0058] Fig. 9 A schematic diagram of a horizontal area provided in an embodiment of the present application;

[0059] Fig.10 A schematic diagram of a vertical region provided for an embodiment of the present application;

[0060] Fig.11 A schematic diagram of a corner point area provided in an embodiment of the present application;

[0061] Fig.12 A schematic diagram of the position of the corner point area in the calibration plate image provided in an embodiment of the present application;

[0062] Fig.13 A schematic diagram of a corner point standard template image corresponding to a corner point area provided in an embodiment of the present application;

[0063] Fig.14 A schematic diagram of a target calibration plate image provided in an embodiment of the present application;

[0064] Fig.15 A schematic diagram of a region of interest for a corner point provided in an embodiment of the present application;

[0065] Fig.16 A schematic diagram of a horizontal gradient curve provided in an embodiment of the present application;

[0066] Fig.17 A schematic diagram of a vertical gradient curve provided in an embodiment of the present application;

[0067] Fig.18 A schematic diagram of a workbench coordinate system provided in an embodiment of the present application;

[0068] Fig.19 A schematic diagram of the structure of a relative position calibration device for an alignment camera and a measurement camera provided in an embodiment of the present application;

[0069] Fig. 20 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0070] In the following description, in order to ensure the accuracy of the citation and the fluency of reading, the key technical terms, abbreviations or abbreviations involved in the text are summarized and explained as follows:

[0071] The following describes the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation method section of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application.

[0072] The embodiments of the present application are described below in conjunction with the accompanying drawings. Those skilled in the art will appreciate that, with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0073] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and need not be used to describe a specific order or sequential order. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, which is only to describe the distinction mode adopted by the objects of the same attributes when describing in the embodiments of the present application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, so that the process, method, system, product or equipment comprising a series of units need not be limited to those units, but may include other units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0074] Currently, the relative position of the two cameras is calibrated using a Figure 1 However, since the field of view of the alignment camera is 25 times that of the measurement camera, it is not possible to use a circle of the same size that can be seen clearly under the alignment camera and completely under the measurement camera. Figure 1 The circular image shown cannot meet the relative position calibration requirements of the alignment camera and the measurement camera.

[0075] And use Figure 2 The two circles of different sizes shown are used as calibration plate images, so that the centers of the large circle and the small circle coincide. The large circle is used to calibrate the position of the alignment camera, and the small circle is used to calibrate the position of the measurement camera. However, the processing accuracy of the calibration plate image will affect the center coincidence accuracy of the two circles, thereby affecting the relative position calibration accuracy of the alignment camera and the measurement camera. That is, if there is a deviation between the positions of the centers of the large circle and the small circle, this deviation will be substituted into the relative position calibration error of the alignment camera and the measurement camera.

[0076] In order to solve the above technical problems, the embodiment of the present application provides a relative position calibration method for an alignment camera and a measurement camera. The relative position calibration method for an alignment camera and a measurement camera of the embodiment of the present application is described in detail below with reference to the accompanying drawings.

[0077] Reference Figure 3 , Figure 3 A schematic diagram of the process of a relative position calibration method for an alignment camera and a measurement camera provided in an embodiment of the present application is shown as follows: Figure 3 As shown, a relative position calibration method for an alignment camera and a measurement camera provided in an embodiment of the present application may include steps 301 to 304, and these steps are described in detail below.

[0078] 301: Move the alignment camera to a first preset position to obtain a first calibration plate image, where the first preset position corresponds to the position coordinates of the alignment camera in the workbench coordinate system, and the first calibration plate image includes a corner point formed by two right-angled sides;

[0079] like Figure 4 As shown in the calibration pattern, this embodiment uses a calibration pattern with right-angled edge features. The corner points of the right-angled edge themselves have positioning features in the X and Y directions, have directional uniqueness, and can be imaged under the alignment camera and the measurement camera at the same time, so that it can stably and reliably realize the position calibration between the alignment camera and the measurement camera.

[0080] 302: Move the measurement camera to a second preset position to obtain a second calibration plate image, where the second preset position corresponds to the position coordinates of the measurement camera in the workbench coordinate system, and the second calibration plate image includes the above-mentioned corner points;

[0081] When the alignment camera and the measurement camera are imaging, it is necessary to ensure that there is only one corner point in the entire field of view. For example, the first calibration plate image obtained by the alignment camera is as follows: Figure 5 As shown, the second calibration plate image obtained by the measurement camera is as follows Figure 6 shown.

[0082] 303: Determine a first corner point coordinate of the corner point in the first calibration plate image, and determine a second corner point coordinate of the corner point in the second calibration plate image;

[0083] After acquiring the first calibration plate image and the second calibration plate image, corner point detection is performed to obtain first corner point coordinates of the corner point in the first calibration plate image, and second corner point coordinates of the corner point in the second calibration plate image are determined.

[0084] It should be noted that the first corner point coordinates are the pixel coordinates of the corner point under the alignment camera, and the second corner point coordinates are the pixel coordinates of the corner point under the measurement camera.

[0085] 304: Determine position calibration information between the alignment camera and the measurement camera by using the matching relationship between the first corner point coordinates and the second corner point coordinates.

[0086] By using the matching relationship between the coordinates of the first corner point and the coordinates of the second corner point, the relative positions of the alignment camera and the measurement camera are obtained through a series of coordinate conversion calculations.

[0087] The present embodiment discloses a relative position calibration method for an alignment camera and a measurement camera, which selects a calibration plate image including two right-angled sides, takes the corner points of the two right-angled sides as calibration target points, first obtains the coordinates of the first corner point in the first calibration plate image under the alignment camera, then obtains the coordinates of the second corner point in the second calibration plate image under the measurement camera, and finally obtains the relative position relationship between the alignment camera and the measurement camera through coordinate conversion. Since the calibration plate image includes two right-angled sides, has positioning features in the horizontal and vertical directions, has directional uniqueness, and can be imaged under the alignment camera and the measurement camera at the same time, it can accurately realize the relative position calibration of the alignment camera and the measurement camera.

[0088] In a possible implementation, determining a first corner point coordinate of the corner point in the first calibration plate image, and determining a second corner point coordinate of the corner point in the second calibration plate image includes:

[0089] Perform the following operations on the calibration plate images acquired by the alignment camera and the measurement camera:

[0090] 3031: Perform edge detection on the calibration plate image, and determine the position of the corner point area in the calibration plate image according to the edge detection result;

[0091] Perform edge detection on the calibration plate image to identify the right-angled edges in the horizontal direction and the right-angled edges in the vertical direction. Since the corner point is the intersection of the right-angled edges in the horizontal direction and the right-angled edges in the vertical direction, the corner point area can be obtained after identifying the right-angled edges in the horizontal direction and the vertical direction.

[0092] 3032: Perform tilt correction on the calibration plate image to obtain a target calibration plate image;

[0093] Noise or errors in image capture, edge detection or other processes may cause the two right-angled sides of the corner points in the calibration plate image to not be in the horizontal and vertical directions. In order to improve the calculation accuracy, the calibration plate image needs to be tilted so that the two right-angled sides of the corner points in the corrected target calibration plate image are in the horizontal and vertical directions respectively.

[0094] 3033: Determine the pixel coordinates of the corner points in the target calibration plate image;

[0095] The principle of determining the pixel coordinates of the corner point is still to determine the pixel coordinates of the corner point according to the intersection of the two right-angle sides of the corner point.

[0096] 3034: Determine the pixel coordinates of the corner points in the calibration plate image according to the inclination angle of the right-angled side in the calibration plate image and the pixel coordinates of the corner points in the target calibration plate image.

[0097] That is, the pixel coordinates of the corner points in the target calibration plate image are restored to the pixel coordinates of the corner points in the calibration plate image before tilt correction.

[0098] In a possible implementation, step 3031 in the above embodiment includes the following steps A1-A4:

[0099] A1: Perform edge detection on the calibration plate image to obtain the edge area;

[0100] There are many methods for edge detection of the calibration plate image, such as using the Sobel algorithm for edge detection, using the Prewitt operator for edge detection, using the Canny operator for edge detection, etc.

[0101] Exemplarily, the Sobel algorithm is used for edge detection.

[0102] The Sobel calculation formula is as follows:

[0103]

[0104]

[0105]

[0106] Where A is the gray value of the current pixel, Gx is the gray value of the pixel after filtering in the x direction, Gy is the gray value of the pixel after filtering in the y direction, and G is the gray value obtained after the sobel filter is performed on the pixel.

[0107] After the Sobel algorithm is used, we can get Figure 7 The edge intensity image shown in FIG. 1 is then binarized to obtain the following: Figure 8 The edge region after binarization is shown.

[0108] A2: Open the edge area in the horizontal direction, remove the vertical noise area, and obtain the horizontal area;

[0109] The edge region is opened in the horizontal direction, that is, the edge region is opened in the X direction, and then the edge region in the vertical direction is removed, that is, the noise region in the vertical direction is removed, and the following is obtained: Fig. 9 The horizontal area.

[0110] A3: Open the edge area in the vertical direction, remove the noise area in the horizontal direction, and obtain the vertical area;

[0111] The edge area is opened in the vertical direction, that is, the edge area is opened in the Y direction, and then the edge area in the horizontal direction is removed, that is, the noise area in the horizontal direction is removed, and the following is obtained: Fig.10 The vertical area.

[0112] A4: The intersection of the horizontal area and the vertical area is determined as the original corner point area.

[0113] It can be understood that the corner point is the intersection of the horizontal right angle side and the vertical right angle side, so the intersection of the horizontal area and the vertical area is as follows: Fig.11 The corner point area shown in the figure, the position of the corner point area in the calibration plate image is as follows Fig.12 shown.

[0114] In a possible implementation, step 3032 in the above embodiment includes the following steps B1-B6:

[0115] B1: Generate a rectangular box of preset size in the corner point area and calculate the grayscale mean in the rectangular box;

[0116] Exemplarily, a 64×64 rectangular frame is generated with the corner point region as the center (64×64 is only an example, and rectangular frames of other sizes may also be generated).

[0117] B2: Use the grayscale mean as the threshold and binarize the image in the rectangular frame to obtain the foreground area and background area;

[0118] The grayscale value of the point whose grayscale value is greater than the threshold is set as the first pixel value, and the grayscale value of the point whose grayscale value is less than the threshold is set as the second pixel value, so that the corner point area can be clearly divided into two parts, namely the foreground area and the background area.

[0119] B3: Calculate the grayscale mean of the foreground area and the background area respectively;

[0120] B4: Generate a corner point standard template image based on the grayscale mean of the foreground area and the background area;

[0121] It can be understood that when a 64×64 rectangular box is generated with the corner point area as the center, if the right-angle side of the corner point is not tilted, the lower right 1 / 4 area of ​​the rectangular box should be the foreground area, and the remaining 3 / 4 area should be the background area. Fig.13 As shown, the lower right 1 / 4 area in the rectangular frame is used as the target foreground area in the corner point standard template image, and the remaining 3 / 4 area is used as the target background area in the corner point standard template image, and the angle of the horizontal boundary of the target foreground area is 0, that is, the angle of the horizontal right-angle side of the corner point is 0.

[0122] B5: Perform template matching on the corner point standard template image and the calibration plate image to calculate the inclination angle of the right-angle edge in the calibration plate image;

[0123] Specifically, the corner point standard template image is template matched in the calibration plate image according to the position of the corner point area, so that the corner point area in the corner point standard template image coincides with the corner point area in the calibration plate image. The angle between the horizontal right-angled side in the corner point standard template image and the horizontal right-angled side in the calibration plate image is the inclination θ of the right-angled side in the calibration plate image.

[0124] B6: Perform tilt correction on the calibration plate image according to the tilt angle to obtain the target calibration plate image.

[0125] like Fig.14 As shown, through tilt correction, the two right-angled sides in the target calibration plate image are respectively coincident with the two right-angled sides of the corner point standard template image, that is, the two right-angled sides of the corner point in the target calibration plate image are respectively in the horizontal direction and the vertical direction.

[0126] In a possible implementation, step 3033 in the above embodiment includes the following steps C1-C3:

[0127] C1: Perform grayscale projection of the image in the horizontal and vertical directions in the region of interest of the corner point in the target calibration plate image to obtain the grayscale curves in the horizontal and vertical directions;

[0128] like Fig.15 As shown, a 64×64 rectangular region of interest is generated with the corner point area as the center in the target calibration plate image (regions of interest of other sizes can also be generated), and grayscale projection is performed on the image in the horizontal direction (ie, X direction) and the vertical direction (ie, Y direction) in the region of interest.

[0129] C2: Calculate the gradient curves corresponding to the grayscale curves in the horizontal and vertical directions respectively, and determine the position with the largest gradient as the edge position;

[0130] The first-order derivatives of the grayscale curves in the horizontal and vertical directions are calculated to obtain the gradient curves in the horizontal and vertical directions, such as Fig.16 The horizontal gradient curve shown in FIG. 1 has the largest gradient at the edge of the horizontal direction. Fig.17 In the vertical gradient curve shown, the position with the maximum gradient is the edge position in the vertical direction.

[0131] C3: Determine the pixel coordinates of the corner points in the target calibration plate image based on the edge positions in the horizontal and vertical directions.

[0132] The edge position in the horizontal direction determines the abscissa Px1' of the corner point, and the edge position in the vertical direction determines the ordinate Py1' of the corner point, thereby obtaining the pixel coordinates (Px1', Py1') of the corner point in the target calibration plate image.

[0133] Furthermore, after obtaining the pixel coordinates of the corner points in the target calibration plate image (Px1', Py1'), it is necessary to restore the coordinate position of the pixel coordinates of the corner points to the position coordinates before the tilt correction, that is, rotate θ degrees around the image center to obtain the original pixel coordinates of the corner points (Px1, Py1). The calculation formula is as follows:

[0134] .

[0135] The pixel coordinates of the corner points in the first calibration plate image are the first corner point coordinates, and the pixel coordinates of the corner points in the second calibration plate image are the second corner point coordinates.

[0136] After obtaining the coordinates of the first corner point and the coordinates of the second corner point, the position calibration information between the alignment camera and the measurement camera can be determined by using the matching relationship between the coordinates of the first corner point and the coordinates of the second corner point. In a possible implementation, the following steps D1-D3 are specifically included:

[0137] D1: Determine a first calculation relationship between the coordinates of the first corner point and the central pixel coordinates of the first calibration plate image, the pre-calibrated pixel equivalent under the alignment camera, the position coordinates of the alignment camera in the workbench coordinate system, and the physical coordinates of the corner point under the alignment camera;

[0138] D2: Determine a second calculation relationship between the coordinates of the second corner point and the central pixel coordinates of the second calibration plate image, the pixel equivalent under the pre-calibrated measurement camera, the position coordinates of the measurement camera in the workbench coordinate system, and the physical coordinates of the corner point under the measurement camera;

[0139] D3: Make the physical coordinates of the corner point under the alignment camera equal to the physical coordinates of the corner point under the measurement camera, and determine the relative position of the alignment camera and the measurement camera according to the first calculation relationship and the second calculation relationship.

[0140] like Fig.18 As shown, when the alignment camera moves to the first preset position, the position coordinates (xa, ya) of the alignment camera in the workbench coordinate system are obtained, and the coordinates of the first corner point (Px1, Py1) are calculated. When the measurement camera moves to the second preset position, the position coordinates (xm, ym) of the measurement camera in the workbench coordinate system are obtained, and the coordinates of the second corner point (Px2, Py2) are calculated.

[0141] In this embodiment, the pixel equivalents PixelSizeX1 and PixelSizeY1 under the alignment camera and the pixel equivalents PixelSizeX2 and PixelSizeY2 under the measurement camera are pre-calibrated. In addition, the center pixel coordinates (Pxa, Pya) of the first calibration plate image and the center pixel coordinates (Pxm, Pym) of the first calibration plate image are known.

[0142] Let the physical coordinates of the corner point under the alignment camera be (x1, y1), then the first calculation relationship between the coordinates of the first corner point and the central pixel coordinates of the first calibration plate image, the pre-calibrated pixel equivalent under the alignment camera, the position coordinates of the alignment camera in the workbench coordinate system, and the physical coordinates of the corner point under the alignment camera is as follows:

[0143] x1 = xa + (Px1-Pxa) × PixelSizeX1 (1),

[0144] y1 = ya - (Py1-Pya) × PixelSizeY1 (2).

[0145] Let the physical coordinates of the corner point under the measurement camera be (x2, y2), then the second calculation relationship between the coordinates of the second corner point and the central pixel coordinates of the second calibration plate image, the pre-calibrated pixel equivalent under the measurement camera, the position coordinates of the measurement camera in the workbench coordinate system, and the physical coordinates of the corner point under the measurement camera is as follows:

[0146] x2 = xm + (Px2-Pxm) × PixelSizeX2 (3),

[0147] y2 = ym - (Py2-Pym) × PixelSizeY2 (4).

[0148] Since the physical coordinates of the corner points calculated under the alignment camera and the physical coordinates calculated under the measurement camera are theoretically coincident, we have:

[0149] x1 = x2 (5)

[0150] y1 = y2 (6)

[0151] The positional relationship between the alignment camera and the measurement camera is calculated by formulas (1)-(6) as follows:

[0152] Δx = xm - xa = -(Px2-Pxm) × PixelSizeX2 + (Px1-Pxa) × PixelSizeX1,

[0153] Δy = ym - ya = (Py2-Pym) × PixelSizeY2 - (Py1-Pya) × PixelSizeY1.

[0154] A relative position calibration method for an alignment camera and a measurement camera provided in an embodiment of the present application is introduced above. A device for executing the relative position calibration method for an alignment camera and a measurement camera will be introduced below.

[0155] See also Fig.19 , Fig.19 This is a schematic diagram of the structure of a wafer center positioning device provided in an embodiment of the present application. Fig.19 As shown, the relative position calibration device of the alignment camera and the measurement camera includes:

[0156] A first image acquisition unit 1901 is used to move the alignment camera to a first preset position to acquire a first calibration plate image, where the first preset position corresponds to the position coordinates of the alignment camera in the workbench coordinate system, and the first calibration plate image includes a corner point formed by two right-angled sides;

[0157] A second image acquisition unit 1902 is used to move the measurement camera to a second preset position to acquire a second calibration plate image, where the second preset position corresponds to the position coordinates of the measurement camera in the workbench coordinate system, and the second calibration plate image includes the corner point;

[0158] A coordinate determining unit 1903, configured to determine a first corner point coordinate of the corner point in the first calibration plate image, and determine a second corner point coordinate of the corner point in the second calibration plate image;

[0159] The calibration unit 1904 is configured to determine position calibration information between the alignment camera and the measurement camera by using the matching relationship between the first corner point coordinates and the second corner point coordinates.

[0160] In a possible implementation, the calibration unit 1904 is specifically used to determine a first calculation relationship between the coordinates of the first corner point and the center pixel coordinates of the first calibration plate image, the pre-calibrated pixel equivalent under the alignment camera, the position coordinates of the alignment camera in the workbench coordinate system, and the physical coordinates of the corner point under the alignment camera; determine a second calculation relationship between the coordinates of the second corner point and the center pixel coordinates of the second calibration plate image, the pre-calibrated pixel equivalent under the measurement camera, the position coordinates of the measurement camera in the workbench coordinate system, and the physical coordinates of the corner point under the measurement camera; make the physical coordinates of the corner point under the alignment camera equal to the physical coordinates of the corner point under the measurement camera, and determine the relative position of the alignment camera and the measurement camera according to the first calculation relationship and the second calculation relationship.

[0161] In a possible implementation, the coordinate determining unit 1903 includes:

[0162] An edge detection subunit is used to perform edge detection on the calibration plate image and determine the position of the corner point area in the calibration plate image according to the edge detection result;

[0163] A tilt correction subunit, used for performing tilt correction on the calibration plate image to obtain a target calibration plate image, wherein two right-angled sides of the corner point in the target calibration plate image are respectively in the horizontal direction and the vertical direction;

[0164] A first coordinate determination subunit, used to determine the pixel coordinates of corner points in the target calibration plate image;

[0165] A second coordinate determination subunit, configured to determine the pixel coordinates of the corner points in the calibration plate image according to the inclination angle of the right-angled side in the calibration plate image and the pixel coordinates of the corner points in the target calibration plate image;

[0166] The pixel coordinates of the corner points in the first calibration plate image are the first corner point coordinates, and the pixel coordinates of the corner points in the second calibration plate image are the second corner point coordinates.

[0167] In a possible implementation, the edge detection subunit is specifically used to perform edge detection on the calibration plate image to obtain an edge area; perform an opening operation on the edge area in the horizontal direction, remove the noise area in the vertical direction, and obtain a horizontal area; perform an opening operation on the edge area in the vertical direction, remove the noise area in the horizontal direction, and obtain a vertical area; and determine the intersection of the horizontal area and the vertical area as the corner point area.

[0168] In a possible implementation, the tilt correction subunit is specifically used to generate a rectangular frame of a preset size in the corner point area, calculate the grayscale mean in the rectangular frame; use the grayscale mean as a threshold, binarize the image in the rectangular frame to obtain a foreground area and a background area; calculate the grayscale means of the foreground area and the background area respectively; generate a corner point standard template image according to the grayscale means of the foreground area and the background area; perform template matching on the corner point standard template image in the calibration plate image, and calculate the tilt angle of the right-angled side in the calibration plate image; perform tilt correction on the calibration plate image according to the tilt angle to obtain the target calibration plate image.

[0169] In a possible implementation, the first coordinate determination subunit is specifically used to perform grayscale projection of the image in the horizontal and vertical directions within the region of interest of the corner point in the target calibration plate image, respectively, to obtain grayscale curves in the horizontal and vertical directions; calculate the gradient curves corresponding to the grayscale curves in the horizontal and vertical directions, respectively, and determine the position with the largest gradient as the edge position; and determine the pixel coordinates of the corner point in the target calibration plate image according to the edge positions in the horizontal and vertical directions.

[0170] This embodiment discloses a relative position calibration device for an alignment camera and a measurement camera, which selects a calibration plate image including two right-angled sides, takes the corner points of the two right-angled sides as calibration target points, first obtains the coordinates of the first corner point in the first calibration plate image under the alignment camera, then obtains the coordinates of the second corner point in the second calibration plate image under the measurement camera, and finally obtains the relative position relationship between the alignment camera and the measurement camera through coordinate conversion. Since the calibration plate image includes two right-angled sides, has positioning features in the horizontal and vertical directions, has directional uniqueness, and can be imaged under the alignment camera and the measurement camera at the same time, it can accurately realize the relative position calibration of the alignment camera and the measurement camera.

[0171] The present application also provides an electronic device in an embodiment. Fig. 20 As shown, it shows a schematic diagram of the structure of an electronic device suitable for implementing the embodiment of the present application. The electronic device in the embodiment of the present application may include but is not limited to fixed terminals such as mobile phones, laptops, PDAs (personal digital assistants), PADs (tablet computers), desktop computers, etc. Fig. 20 The electronic device shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0172] like Fig. 20As shown, the electronic device may include a processing device (e.g., a central processing unit, a graphics processing unit, etc.) 701, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 702 or a program loaded from a storage device 708 to a random access memory (RAM) 703. When the electronic device is powered on, various programs and data required for the operation of the electronic device are also stored in the RAM 703. The processing device 701, the ROM 702, and the RAM 703 are connected to each other via a bus 704. An input / output (I / O) interface 705 is also connected to the bus 704.

[0173] Typically, the following devices may be connected to the I / O interface 705: an input device 706 including, for example, a touch screen, a touch pad, a keyboard, a mouse, a camera, a microphone, an accelerometer, a gyroscope, etc.; an output device 707 including, for example, a liquid crystal display (LCD), a speaker, a vibrator, etc.; a storage device 708 including, for example, a memory card, a hard disk, etc.; and a communication device 709. The communication device 709 may allow the electronic device to communicate with other devices wirelessly or by wire to exchange data. Although Fig. 20 An electronic device having various devices is shown, but it should be understood that it is not required to implement or possess all the devices shown. More or fewer devices may be implemented or possessed instead.

[0174] An embodiment of the present application also provides a computer program product including computer-readable instructions. When the computer-readable instructions are executed on an electronic device, the electronic device implements any relative position calibration method of an alignment camera and a measurement camera provided in the embodiment of the present application.

[0175] A computer-readable storage medium is also provided in an embodiment of the present application. The storage medium carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement any relative position calibration method of an alignment camera and a measurement camera provided in an embodiment of the present application.

[0176] It should also be noted that the device embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed over multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. In addition, in the drawings of the device embodiments provided by the present application, the connection relationship between the modules indicates that there is a communication connection between them, which may be specifically implemented as one or more communication buses or signal lines.

[0177] Through the description of the above implementation mode, the technicians in the field can clearly understand that the present application can be implemented by means of software plus necessary general hardware, and of course, it can also be implemented by special hardware including special integrated circuits, special CPUs, special memories, special components, etc. In general, all functions completed by computer programs can be easily implemented by corresponding hardware, and the specific hardware structure used to implement the same function can also be various, such as analog circuits, digital circuits or special circuits. However, for the present application, software program implementation is a better implementation mode in more cases. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a readable storage medium, such as a computer floppy disk, a U disk, a mobile hard disk, a ROM, a RAM, a disk or an optical disk, etc., including a number of instructions to enable a computer device (which can be a personal computer, a training device, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0178] In the above embodiments, all or part of the embodiments may be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments may be implemented in the form of a computer program product.

[0179] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website site, a computer, a training device, or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, training device, or data center. The computer-readable storage medium may be any available medium that a computer can store or a data storage device such as a training device, a data center, etc. that includes one or more available media integrations. The available medium may be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)), etc.

Claims

1. A relative position calibration method for an alignment camera and a measurement camera, characterized in that: include: Move the alignment camera to a first preset position to acquire a first calibration plate image, wherein the first preset position corresponds to the position coordinates of the alignment camera in the workbench coordinate system, and the first calibration plate image includes a corner point formed by two right-angled sides; Move the measurement camera to a second preset position to obtain a second calibration plate image, wherein the second preset position corresponds to the position coordinates of the measurement camera in the workbench coordinate system, and the second calibration plate image includes the corner point; Determine the first corner point coordinates of the corner point in the first calibration plate image, and determine the second corner point coordinates of the corner point in the second calibration plate image; Position calibration information between the alignment camera and the measurement camera is determined by using the matching relationship between the first corner point coordinates and the second corner point coordinates.

2. The relative position calibration method of the alignment camera and the measurement camera according to claim 1, characterized in that: The determining the position calibration information between the alignment camera and the measurement camera by using the matching relationship between the first corner point coordinates and the second corner point coordinates includes: Determine a first calculation relationship between the coordinates of the first corner point and the central pixel coordinates of the first calibration plate image, the pre-calibrated pixel equivalent under the alignment camera, the position coordinates of the alignment camera in the workbench coordinate system, and the physical coordinates of the corner point under the alignment camera; Determine a second calculation relationship between the coordinates of the second corner point and the central pixel coordinates of the second calibration plate image, the pre-calibrated pixel equivalent of the measurement camera, the position coordinates of the measurement camera in the workbench coordinate system, and the physical coordinates of the corner point in the measurement camera; The physical coordinates of the corner point under the alignment camera are made equal to the physical coordinates of the corner point under the measurement camera, and the relative positions of the alignment camera and the measurement camera are determined according to the first calculation relationship and the second calculation relationship.

3. The relative position calibration method of an alignment camera and a measurement camera according to claim 1, characterized in that: The determining of the first corner point coordinates of the corner point in the first calibration plate image, and determining the second corner point coordinates of the corner point in the second calibration plate image, comprises: The following operations are performed respectively for the calibration plate images acquired by the alignment camera and the measurement camera: Performing edge detection on the calibration plate image, and determining the position of the corner point area in the calibration plate image according to the edge detection result; Performing tilt correction on the calibration plate image to obtain a target calibration plate image, wherein two right-angled sides of the corner point in the target calibration plate image are respectively in the horizontal direction and the vertical direction; Determine the pixel coordinates of the corner points in the target calibration plate image; Determining the pixel coordinates of the corner points in the calibration plate image according to the inclination angle of the right-angled side in the calibration plate image and the pixel coordinates of the corner points in the target calibration plate image; The pixel coordinates of the corner points in the first calibration plate image are the first corner point coordinates, and the pixel coordinates of the corner points in the second calibration plate image are the second corner point coordinates.

4. The relative position calibration method of the alignment camera and the measurement camera according to claim 3, characterized in that: The performing edge detection on the calibration plate image and determining the position of the corner point area in the calibration plate image according to the edge detection result includes: Perform edge detection on the calibration plate image to obtain the edge area; Performing an opening operation on the edge region in the horizontal direction, removing the noise region in the vertical direction, and obtaining a horizontal region; Performing an opening operation on the edge region in the vertical direction, removing the noise region in the horizontal direction, and obtaining a vertical region; An intersection of the horizontal area and the vertical area is determined as the corner point area.

5. The relative position calibration method of an alignment camera and a measurement camera according to claim 3, characterized in that: The step of performing tilt correction on the calibration plate image to obtain a target calibration plate image comprises: Generate a rectangular frame of a preset size in the corner point area, and calculate the grayscale mean in the rectangular frame; Using the grayscale mean as a threshold, binarizing the image in the rectangular frame to obtain a foreground area and a background area; Calculating grayscale means of the foreground area and the background area respectively; Generate a corner point standard template image according to the grayscale mean of the foreground area and the background area; Perform template matching on the corner point standard template image and the calibration plate image to calculate the inclination angle of the right-angle side in the calibration plate image; The calibration plate image is tilt-corrected according to the tilt angle to obtain the target calibration plate image.

6. The relative position calibration method of an alignment camera and a measurement camera according to claim 3, characterized in that: The step of determining pixel coordinates of corner points in the target calibration plate image comprises: Performing grayscale projection on the image in the horizontal direction and the vertical direction in the region of interest of the corner point in the target calibration plate image, respectively, to obtain grayscale curves in the horizontal direction and the vertical direction; Calculate the gradient curves corresponding to the grayscale curves in the horizontal and vertical directions respectively, and determine the position with the largest gradient as the edge position; The pixel coordinates of the corner points in the target calibration plate image are determined according to the edge positions in the horizontal direction and the vertical direction.

7. A relative position calibration device for an alignment camera and a measurement camera, characterized in that: include: A first image acquisition unit, used for moving the alignment camera to a first preset position to acquire a first calibration plate image, wherein the first preset position corresponds to the position coordinates of the alignment camera in the workbench coordinate system, and the first calibration plate image includes a corner point formed by two right-angled sides; A second image acquisition unit, used for moving the measurement camera to a second preset position to acquire a second calibration plate image, wherein the second preset position corresponds to the position coordinates of the measurement camera in the workbench coordinate system, and the second calibration plate image includes the corner point; a coordinate determination unit, configured to determine a first corner point coordinate of the corner point in the first calibration plate image, and determine a second corner point coordinate of the corner point in the second calibration plate image; A calibration unit is used to determine position calibration information between the alignment camera and the measurement camera by using the matching relationship between the first corner point coordinates and the second corner point coordinates.

8. An electronic device, characterized in that: The method comprises at least one processor and a memory connected to the processor, wherein: The memory is used to store computer programs; The processor is used to execute the computer program so that the electronic device can implement the relative position calibration method of the alignment camera and the measurement camera as described in any one of claims 1 to 6.

9. A computer program product, characterized in that It comprises computer-readable instructions, and when the computer-readable instructions are executed on an electronic device, the electronic device implements the relative position calibration method of an alignment camera and a measurement camera as claimed in any one of claims 1 to 6.

10. A computer storage medium, characterized in that: The storage medium carries one or more computer programs, and when the one or more computer programs are executed by an electronic device, the electronic device can implement the relative position calibration method of the alignment camera and the measurement camera as described in any one of claims 1 to 6.

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