A method for positioning the center of an overlay mark and a related device

Abstract

The present application discloses a method for locating the center of an overlay mark and a related device, which relate to the field of chip manufacturing technology. First, a preset region of interest is used to determine the approximate position of the overlay mark. Then, a one-dimensional grayscale curve is generated by performing grayscale projection of the overlay mark image in the horizontal and vertical directions in the preset region of interest, and the two-dimensional information of the overlay mark image is reduced to one dimension, thereby effectively reducing the amount of calculated data. Then, a target curve is obtained by performing noise reduction processing on the one-dimensional grayscale curve, thereby reducing noise interference and ensuring the accuracy and effectiveness of the overlay mark center positioning. Finally, the prior knowledge that the overlay mark is symmetrical in the horizontal and vertical directions is used to calculate the symmetric length of each point within the target search range of the target curve, thereby obtaining a symmetric curve composed of the symmetric length of each point, and the peak value of the symmetric curve is determined as the overlay mark center, thereby ensuring the accuracy and reliability of the overlay mark center.

Description

Technical Field

[0001] The present application relates to the field of chip manufacturing technology, and in particular to a method for positioning the center of an overlay mark 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 center of the overlay mark must be accurately aligned. The higher the alignment accuracy, the higher the accuracy of the overlay deviation measurement. Otherwise, the overlay deviation cannot be well compensated and corrected, resulting in an overall decrease in chip performance. Therefore, there is an urgent need in the art for a method that can achieve accurate alignment of the center of the overlay mark. Summary of the invention

[0004] In view of the above problems, the present application provides a method and a related device for locating the center of an overlay mark to ensure the accuracy and reliability of the center of the overlay mark. The specific solution is as follows:

[0005] The first aspect of the present application provides a method for locating the center of an overlay mark, comprising:

[0006] Performing grayscale projection of the overlay mark image in the preset region of interest in the horizontal direction and the vertical direction to generate a one-dimensional grayscale curve, wherein the overlay mark image is symmetrical in the horizontal direction and the vertical direction;

[0007] Performing noise reduction processing on the one-dimensional grayscale curve to obtain a target curve;

[0008] The symmetric lengths of the preset points are calculated within the target search range of the target curve to obtain a symmetric curve composed of the symmetric lengths of each preset point, and the peak value of the symmetric curve is determined as the center of the overlay mark.

[0009] In a possible implementation, performing noise reduction processing on the one-dimensional grayscale curve to obtain a target curve includes:

[0010] The one-dimensional grayscale curve is subjected to filtering processing.

[0011] In a possible implementation, the performing noise reduction processing on the one-dimensional grayscale curve to obtain a target curve further includes:

[0012] Normalize the grayscale values ​​in the filtered curve.

[0013] In a possible implementation, the performing noise reduction processing on the one-dimensional grayscale curve to obtain a target curve further includes:

[0014] The normalized curve is quantized to obtain the target curve.

[0015] In a possible implementation, the method for determining the target search range includes:

[0016] A gradient curve corresponding to the target curve is calculated, and a starting position and an ending position of the overlay mark are determined according to a gradient in the gradient curve, so as to obtain the target search range between the starting position and the ending position of the overlay mark.

[0017] In a possible implementation, after determining the peak value of the symmetry curve as the overlay mark center, the overlay mark center positioning method further includes:

[0018] An interpolation process is performed on the peak value of the symmetric curve to obtain the overlay mark center after the interpolation process.

[0019] A second aspect of the present application provides an overlay mark center positioning device, comprising:

[0020] A projection unit, used for performing grayscale projection of the overlay mark image in the horizontal direction and the vertical direction in a preset region of interest to generate a one-dimensional grayscale curve, wherein the overlay mark image is symmetrical in the horizontal direction and the vertical direction;

[0021] A noise reduction unit, used for performing noise reduction processing on the one-dimensional grayscale curve to obtain a target curve;

[0022] The calculation unit is used to calculate the symmetric length of the preset points within the target search range of the target curve, obtain a symmetric curve composed of the symmetric lengths of each preset point, and determine the peak value of the symmetric curve as the center of the overlay mark.

[0023] A third aspect of the present application provides an electronic device, comprising at least one processor and a memory connected to the processor, wherein:

[0024] The memory is used to store computer programs;

[0025] The processor is used to execute the computer program so that the electronic device can implement the method for locating the center of the overlay mark of the first aspect or any implementation manner of the first aspect.

[0026] The fourth aspect of the present application provides a computer program product, including computer-readable instructions. When the computer-readable instructions are executed on an electronic device, the electronic device implements the method for locating the center of an overlay mark according to the first aspect or any implementation of the first aspect.

[0027] 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 implement the method for locating the center of the overlay mark according to the first aspect or any implementation of the first aspect.

[0028] By means of the above technical scheme, the present application provides a method for locating the center of an overlay mark and a related device. First, a preset region of interest is used to determine the approximate position of the overlay mark. Then, a one-dimensional grayscale curve is generated by performing grayscale projection of the overlay mark image in the horizontal and vertical directions in the preset region of interest. The two-dimensional information of the overlay mark image is reduced to one dimension, thereby effectively reducing the amount of calculated data. Then, a target curve is obtained by performing denoising processing on the one-dimensional grayscale curve to reduce noise interference and ensure the accuracy and effectiveness of the overlay mark center positioning. Finally, the prior knowledge that the overlay mark is symmetrical in the horizontal and vertical directions is used to calculate the symmetry length of each point within the target search range of the target curve to obtain a symmetric curve composed of the symmetry length of each point. The peak value of the symmetry curve is determined as the center of the overlay mark to ensure the accuracy and reliability of the center of the overlay mark. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] Figure 1 A schematic diagram of a flow chart of a method for locating the center of an overlay mark provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of an overlay mark image provided in an embodiment of the present application;

[0032] Figure 3 A schematic diagram of a one-dimensional grayscale curve in the horizontal direction provided in an embodiment of the present application;

[0033] Figure 4 A schematic diagram of a target curve after quantization processing in the horizontal direction provided in an embodiment of the present application;

[0034] Figure 5 A schematic diagram of a symmetrical curve in the horizontal direction provided in an embodiment of the present application;

[0035] Figure 6 A schematic diagram of the structure of an overlay mark center positioning device provided in an embodiment of the present application;

[0036] Figure 7 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] 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.

[0038] 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.

[0039] 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.

[0040] The embodiment of the present application provides a method for locating the center of an overlay mark. The method for locating the center of an overlay mark in the embodiment of the present application is described in detail below in conjunction with the accompanying drawings.

[0041] Reference Figure 1 , Figure 1 A schematic diagram of a process of locating the center of an overlay mark provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, a method for locating the center of an overlay mark provided in an embodiment of the present application may include steps 101 to 103, and these steps are described in detail below.

[0042] 101: Performing grayscale projection of the overlay mark image in the horizontal direction and the vertical direction in a preset region of interest to generate a one-dimensional grayscale curve;

[0043] like Figure 2 As shown in the schematic diagram of the overlay mark image, the overlay mark image is symmetrical in the horizontal and vertical directions.

[0044] The preset region of interest is used to determine the approximate position of the overlay mark. The preset region of interest may be manually calibrated or automatically generated according to the overlay mark image, which is not specifically limited in this embodiment.

[0045] This embodiment uses a preset region of interest to determine the approximate position of the overlay mark, and then accurately locates it through overlay mark center positioning. It can adapt according to the shape of the overlay mark itself, avoiding the problem of reduced accuracy of overlay mark center positioning due to changes in the size of the overlay mark itself and differences in shape, thereby improving the adaptability and robustness of overlay mark center positioning.

[0046] The overlay mark image is respectively projected in grayscale in the horizontal direction (ie, X direction) and the vertical direction (ie, Y direction) in the preset region of interest to generate a one-dimensional grayscale curve in the horizontal direction and a one-dimensional grayscale curve in the vertical direction.

[0047] For example, the generated one-dimensional grayscale curve in the horizontal direction is as follows: Figure 3 As shown in the figure, through grayscale projection, the two-dimensional information of the preset area of ​​interest is reduced to one dimension, which greatly reduces the amount of data for subsequent calculations, saves computing resources, and thus improves computing efficiency, making it suitable for scenarios with high throughput requirements.

[0048] 102: performing noise reduction processing on the one-dimensional grayscale curve to obtain a target curve;

[0049] In order to reduce the influence of noise on the one-dimensional grayscale curve and improve the accuracy of the center positioning of the overlay mark, this embodiment performs noise reduction processing on the one-dimensional grayscale curve to obtain a target curve.

[0050] Noise reduction can be implemented in a variety of ways, such as using Gaussian filtering algorithm, mean filtering algorithm, median filtering algorithm, bilateral filtering algorithm, etc., which are not specifically limited in this embodiment. Among them, the Gaussian filtering algorithm uses a Gaussian function to perform weighted averaging on the image, which is suitable for removing Gaussian noise and can better retain image details while smoothing the image. The mean filtering algorithm replaces the value of each pixel by calculating the average value of the pixels around each pixel to smooth the image and reduce the impact of noise. The median filtering algorithm replaces the value of each pixel with the median of the pixel values ​​around it, which is particularly suitable for removing impulse noise such as salt and pepper noise, while better maintaining the edge information of the image. The bilateral filtering algorithm combines the characteristics of mean filtering and Gaussian filtering, not only considering the spatial proximity between pixels, but also considering the similarity of pixel values, and is suitable for denoising while maintaining key information.

[0051] Specifically, the one-dimensional grayscale curve in the horizontal direction and the one-dimensional grayscale curve in the vertical direction are subjected to noise reduction processing respectively to obtain a target curve in the horizontal direction and a target curve in the vertical direction.

[0052] 103: Calculate the symmetric lengths of the preset points within the target search range of the target curve, obtain a symmetric curve composed of the symmetric lengths of each preset point, and determine the peak of the symmetric curve as the center of the overlay mark.

[0053] The target search range indicates the range between the start position and the end position of the overlay mark. Searching within the target search range of the target curve can avoid searching within the entire preset region of interest, reduce the search range, further reduce the amount of calculation, and improve the calculation speed.

[0054] Since the overlay mark image is symmetrical in the horizontal and vertical directions, the target curve in the horizontal direction is also symmetrical to the target curve in the vertical direction. By calculating the symmetric length of the preset point within the target search range of the horizontal target curve, a symmetric curve composed of the symmetric length of each preset point is obtained, and the peak value of the symmetric curve is the horizontal coordinate of the center of the overlay mark; by calculating the symmetric length of the preset point within the target search range of the vertical target curve, a symmetric curve composed of the symmetric length of each preset point is obtained, and the peak value of the symmetric curve is the vertical coordinate of the center of the overlay mark.

[0055] The present embodiment discloses a method for locating the center of an overlay mark. First, a preset region of interest is used to determine an approximate position of the overlay mark. Then, a one-dimensional grayscale curve is generated by performing grayscale projection of the overlay mark image in the horizontal and vertical directions within the preset region of interest. The two-dimensional information of the overlay mark image is reduced to one dimension, thereby effectively reducing the amount of calculated data. Then, a target curve is obtained by performing noise reduction processing on the one-dimensional grayscale curve to reduce noise interference and ensure the accuracy and effectiveness of the overlay mark center positioning. Finally, the prior knowledge that the overlay mark is symmetrical in the horizontal and vertical directions is used to calculate the symmetric length of each point within the target search range of the target curve to obtain a symmetric curve composed of the symmetric length of each point. The peak value of the symmetric curve is determined as the overlay mark center to ensure the accuracy and reliability of the overlay mark center.

[0056] In a possible implementation, performing noise reduction processing on a one-dimensional grayscale curve to obtain a target curve includes filtering the one-dimensional grayscale curve. Specifically, filtering is performed on the one-dimensional grayscale curve in the horizontal direction and the one-dimensional grayscale curve in the vertical direction respectively.

[0057] For example, a one-dimensional grayscale curve is subjected to Gaussian filtering. Gaussian filtering takes into account the distance between pixels, and the farther the pixel is from the center pixel, the less influence it has on the center pixel. This weight distribution enables the filtering result to better preserve the edges and details of the image while smoothing the noise. Compared with mean filtering, it can achieve a better balance between denoising and preserving image details.

[0058] The Gaussian filter formula is as follows:

[0059] ,

[0060] in, G ( x, y ) indicates that the Gaussian function is at point ( x, y ), x and y are the column coordinates and row coordinates of the pixel point on the one-dimensional grayscale curve, is the circumference of a circle, ‌ represents the standard deviation of the Gaussian filter, which controls the width of the Gaussian function, that is, the blurriness of the filter. ‌‌The larger it is, the wider the Gaussian function is and the stronger the blur effect is. The smaller it is, the narrower the Gaussian function is and the weaker the blurring effect is.

[0061] Furthermore, the one-dimensional grayscale curve is subjected to denoising to obtain the target curve, and the grayscale values ​​in the filtered curve are normalized. Specifically, the grayscale values ​​in the filtered curve in the horizontal direction and the vertical direction are normalized respectively.

[0062] The normalization formula is:

[0063] ,

[0064] Among them, x is the pixel grayscale value before normalization, y is the pixel grayscale value after normalization, min is the minimum grayscale value in the curve, and max is the maximum grayscale value in the curve.

[0065] The normalization range is (0,1), that is, the grayscale value of the points in the normalized curve is between (0,1). After normalization, the numerical range of subsequent calculations can be unified to ensure the consistency of subsequent calculations.

[0066] Furthermore, performing noise reduction processing on the one-dimensional grayscale curve to obtain the target curve also includes performing quantization processing on the normalized curve to obtain the target curve. Specifically, performing quantization processing on the normalized curve in the horizontal direction to obtain the target curve in the horizontal direction, and performing quantization processing on the normalized curve in the vertical direction to obtain the target curve in the vertical direction.

[0067] There are many ways to quantize the normalized curve, such as 3-bit quantization, 4-bit quantization, 5-bit quantization, 8-level quantization, 16-level quantization, etc. Among them, 3-bit quantization means that the amplitude value of the signal is represented as a 3-bit binary number, which means that there are (2 3 = 8) possible quantization levels. 4-bit quantization provides (2 4= 16) quantization levels, which provides more levels than 3-bit quantization and can provide a more detailed representation. 5-bit quantization provides (2 5 = 32) quantization levels, which is finer than 4-bit quantization. It can be seen that different quantization processing methods have different quantization accuracy, which can be selected according to the actual application scenario.

[0068] Exemplarily, the normalized curve is subjected to 3-bit quantization to obtain a target curve. The 3-bit quantization process is as follows:

[0069] The grayscale value itself ranges from [0,255], which is 8 bits (2 to the 8th power = 256). After quantization to 3 bits (2 to the 3rd power = 8), the grayscale value range becomes [0,7]. The quantization formula is as follows:

[0070] y=int(x / 32), where x is the pixel grayscale value before quantization and y is the pixel grayscale value after quantization.

[0071] Theoretically, the overlay mark itself is symmetrical in the X and Y directions. Due to the influence of production process and imaging illumination, the symmetry of the overlay mark will deteriorate, and there will be a certain degree of grayscale difference and size difference in some parts. After quantization, these subtle differences will be smoothed out, making the target curve closer to symmetry, thereby ensuring the stability and accuracy of the calculation. Figure 4 The schematic diagram of the target curve after quantization processing in the horizontal direction shown has obvious symmetry.

[0072] In one possible implementation, the method for determining the target search range for the horizontal direction and the vertical direction respectively includes: calculating the gradient curve corresponding to the target curve, determining the starting position and the ending position of the overlay mark according to the gradient in the gradient curve, and obtaining the target search range between the starting position and the ending position of the overlay mark.

[0073] The specific method for calculating the gradient curve corresponding to the target curve is as follows: the first-order derivative of the target curve is calculated to obtain the gradient curve corresponding to the target curve. The first-order derivative calculation formula is as follows:

[0074]

[0075] in, x is the coordinate on the target curve, h For the step size when taking the derivative, we usually take h =2.

[0076] If it is a flat area of ​​the overlay mark, the first-order derivative is 0. If it is the edge of the overlay mark, the first-order derivative is not 0. By finding the first non-0 and the last non-0 position, the starting and ending positions of the overlay mark can be determined, thereby determining the target search range. It is possible to avoid searching in the entire preset area of ​​interest, and reducing the search interval can further improve the calculation speed.

[0077] In a possible implementation, the symmetric length of the preset point is calculated within the target curve search range to obtain a symmetric curve composed of the symmetric length of each preset point, and the peak of the symmetric curve is determined as the center of the overlay mark. Specifically, within the target search range, the number of points with equal values ​​on the left and right of the preset point is taken as the symmetric length of the preset point, so that a symmetric curve composed of the symmetric length of each preset point can be obtained, wherein the horizontal coordinate of the curve is the position of the preset point, and the vertical coordinate is the symmetric length. Figure 5 The schematic diagram of the horizontal symmetrical curve is shown. The peak value of the symmetrical curve is the center of the overlay mark, and the abscissa of the peak value of the symmetrical curve is the abscissa of the center of the overlay mark. It can be seen that the peak performance of the symmetrical curve is better, indicating that the accuracy and stability of calculating the center of the overlay mark are well guaranteed.

[0078] Furthermore, in order to obtain a more accurate overlay mark center, such as obtaining an overlay mark center position with sub-pixel accuracy, the peak position of the symmetry curve may be interpolated to obtain the overlay mark center after interpolation.

[0079] Assume that the peak position is x0, the symmetry length is y0, the position of a point on the left side of the peak is x1, the symmetry length is y1, the position of a point on the right side of the peak is x2, the symmetry length is y2, then the center position of the interpolated overlay mark is for:

[0080] .

[0081] It should be noted that the peak value of the symmetrical curve in the horizontal direction is interpolated to obtain the abscissa of the center of the overlay mark after interpolation, and the peak value of the symmetrical curve in the vertical direction is interpolated to obtain the ordinate of the center of the overlay mark after interpolation.

[0082] A method for locating the center of an overlay mark provided in an embodiment of the present application is introduced above, and a device for executing the above method for locating the center of an overlay mark will be introduced below.

[0083] See also Figure 6 , Figure 6 This is a schematic diagram of the structure of a device for locating the center of an overlay mark provided in an embodiment of the present application. Figure 6 As shown, the overlay mark center positioning device comprises:

[0084] The projection unit 601 is used to perform grayscale projection of the overlay mark image in the horizontal direction and the vertical direction in a preset region of interest to generate a one-dimensional grayscale curve, wherein the overlay mark image is symmetrical in the horizontal direction and the vertical direction;

[0085] A noise reduction unit 602, configured to perform noise reduction processing on the one-dimensional grayscale curve to obtain a target curve;

[0086] The calculation unit 603 is used to calculate the symmetric length of the preset points within the target search range of the target curve, obtain a symmetric curve composed of the symmetric lengths of each preset point, and determine the peak value of the symmetric curve as the center of the overlay mark.

[0087] In a possible implementation, the noise reduction unit 602 includes:

[0088] The filtering subunit is used to perform filtering processing on the one-dimensional grayscale curve.

[0089] In a possible implementation, the noise reduction unit 602 further includes:

[0090] The normalization subunit is used to normalize the grayscale value in the filtered curve.

[0091] In a possible implementation, the noise reduction unit 602 further includes:

[0092] The quantization subunit is used to quantize the normalized curve to obtain the target curve.

[0093] In a possible implementation, the overlay mark center positioning device further includes:

[0094] The search range determination unit is used to calculate the gradient curve corresponding to the target curve, determine the starting position and the ending position of the overlay mark according to the gradient in the gradient curve, and obtain the target search range between the starting position and the ending position of the overlay mark.

[0095] In a possible implementation, the overlay mark center positioning device further includes:

[0096] The interpolation processing unit is used to perform interpolation processing on the peak value of the symmetric curve after determining the peak value of the symmetric curve as the overlay mark center, so as to obtain the overlay mark center after the interpolation processing.

[0097] The present embodiment discloses an overlay mark center positioning device, which first determines the approximate position of the overlay mark by using a preset region of interest, and then generates a one-dimensional grayscale curve by performing grayscale projection of the overlay mark image in the horizontal and vertical directions in the preset region of interest, thereby reducing the two-dimensional information of the overlay mark image to one dimension, thereby effectively reducing the amount of calculated data, and then obtains a target curve by performing noise reduction processing on the one-dimensional grayscale curve, thereby reducing noise interference and ensuring the accuracy and effectiveness of the overlay mark center positioning, and finally utilizes the prior knowledge that the overlay mark is symmetrical in the horizontal and vertical directions to calculate the symmetric length of each point within the target search range of the target curve, thereby obtaining a symmetric curve composed of the symmetric length of each point, and determines the peak value of the symmetric curve as the overlay mark center, thereby ensuring the accuracy and reliability of the overlay mark center.

[0098] The present application also provides an electronic device in an embodiment. Figure 7 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. Figure 7 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.

[0099] like Figure 7 As 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.

[0100] 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 Figure 7 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.

[0101] 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 of the overlay mark center positioning methods provided in the embodiments of the present application.

[0102] 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 of the overlay mark center positioning methods provided in the embodiments of the present application.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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 method for locating the center of an overlay mark, characterized in that: include: Performing grayscale projection of the overlay mark image in the preset region of interest in the horizontal direction and the vertical direction to generate a one-dimensional grayscale curve in the horizontal direction and a one-dimensional grayscale curve in the vertical direction, wherein the overlay mark image is symmetrical in the horizontal direction and the vertical direction; Respectively performing noise reduction processing on the one-dimensional grayscale curve in the horizontal direction and the one-dimensional grayscale curve in the vertical direction to obtain a target curve in the horizontal direction and a target curve in the vertical direction; By calculating the symmetric lengths of the preset points within the target search range of the target curve in the horizontal direction, a symmetric curve composed of the symmetric lengths of each preset point is obtained, and the peak value of the symmetric curve is determined as the horizontal coordinate of the center of the overlay mark; by calculating the symmetric lengths of the preset points within the target search range of the target curve in the vertical direction, a symmetric curve composed of the symmetric lengths of each preset point is obtained, and the peak value of the symmetric curve is determined as the vertical coordinate of the center of the overlay mark; the horizontal coordinate and the vertical coordinate of the center of the overlay mark are combined as the center of the overlay mark, wherein, within the target search range, the number of points with equal values ​​on the left and right of the preset point is taken as the symmetric length of the preset point.

2. The method for locating the center of an overlay mark according to claim 1, characterized in that: The step of performing noise reduction processing on the one-dimensional grayscale curve in the horizontal direction and the one-dimensional grayscale curve in the vertical direction to obtain a target curve in the horizontal direction and a target curve in the vertical direction comprises: The one-dimensional grayscale curve in the horizontal direction and the one-dimensional grayscale curve in the vertical direction are filtered respectively.

3. The method for locating the center of an overlay mark according to claim 2, characterized in that: The denoising process is performed on the one-dimensional grayscale curve in the horizontal direction and the one-dimensional grayscale curve in the vertical direction to obtain a target curve in the horizontal direction and a target curve in the vertical direction, and further includes: The grayscale values ​​in the filtered curves are normalized respectively.

4. The method for locating the center of an overlay mark according to claim 3, characterized in that: The denoising process is performed on the one-dimensional grayscale curve in the horizontal direction and the one-dimensional grayscale curve in the vertical direction to obtain a target curve in the horizontal direction and a target curve in the vertical direction, and further includes: The normalized curves are quantized to obtain the target curve in the horizontal direction and the target curve in the vertical direction.

5. The method for locating the center of an overlay mark according to claim 1, characterized in that: The method for determining the target search range includes: A gradient curve corresponding to the target curve is calculated, and a starting position and an ending position of the overlay mark are determined according to a gradient in the gradient curve, so as to obtain the target search range between the starting position and the ending position of the overlay mark.

6. The method for locating the center of an overlay mark according to claim 1, characterized in that: After determining the overlay mark center, the overlay mark center positioning method further includes: An interpolation process is performed on the peak value of the symmetric curve to obtain the overlay mark center after the interpolation process.

7. A device for positioning the center of an engraved mark, characterized in that: include: A projection unit, used for performing grayscale projection of the overlay mark image in the horizontal direction and the vertical direction in a preset region of interest to generate a one-dimensional grayscale curve in the horizontal direction and a one-dimensional grayscale curve in the vertical direction, wherein the overlay mark image is symmetrical in the horizontal direction and the vertical direction; A noise reduction unit, used for performing noise reduction processing on the one-dimensional grayscale curve in the horizontal direction and the one-dimensional grayscale curve in the vertical direction respectively, to obtain a target curve in the horizontal direction and a target curve in the vertical direction; A calculation unit is used to obtain a symmetrical curve composed of the symmetrical lengths of each preset point by calculating the symmetrical lengths of the preset points within the target search range of the target curve in the horizontal direction, and determine the peak value of the symmetrical curve as the horizontal coordinate of the center of the overlay mark; obtain a symmetrical curve composed of the symmetrical lengths of each preset point by calculating the symmetrical lengths of the preset points within the target search range of the target curve in the vertical direction, and determine the peak value of the symmetrical curve as the vertical coordinate of the center of the overlay mark; the horizontal coordinate and the vertical coordinate of the center of the overlay mark are combined to form the center of the overlay mark, wherein, within the target search range, the number of points with equal values ​​on the left and right of the preset point is taken as the symmetrical length of the preset point.

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 overlay mark center positioning method 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 overlay mark center positioning method 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 overlay mark center positioning method as described in any one of claims 1 to 6.

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