A method and apparatus for processing overprinted marking images

Abstract

The embodiment of the present application provides a method and device for processing an overlay mark image, wherein the overlay mark image may include a first graphic and a second graphic, wherein the first graphic and the second graphic are arranged to overlap, the overlay mark image is identified, a first area where the first graphic is located and a second area where the second graphic is located are determined, and when the first area and the second area meet the image contrast condition, the first area and / or the second area are subjected to random error correction processing to reduce the noise in the first area and / or the second area, and the overlay error between the first graphic and the second graphic is calculated based on the corrected overlay mark image. Since the first area and / or the second area are subjected to random error correction processing, the noise therein is suppressed, which is conducive to accurate edge recognition of the first graphic and the second graphic, thereby improving the calculation accuracy of the overlay error, improving the use efficiency of the overlay machine, and improving the tolerance to process fluctuations and process errors.

Description

Technical Field

[0001] The present application relates to the field of integrated circuits, and in particular to a method and device for processing an overlay mark image. Background Art

[0002] In the manufacturing of integrated circuits, there are the following processes: using the photolithography process to expose the first layer of patterns on the silicon wafer, and then the first layer of patterns can be used to perform the first process of the silicon wafer. After the first process is completed, the mask can be replaced, and then the second layer of patterns can be exposed on the silicon wafer, and then the second layer of patterns can be used to perform the second process of the silicon wafer. The objects of the first process and the second process can be different film layers. The first layer of patterns and the second layer of patterns need to be accurately overlapped, so the above process can be called overlay.

[0003] However, in reality, due to the existence of systematic errors and accidental errors, the positions of the first layer of graphics and the second layer of graphics often deviate, that is, there is an overlay error. As the critical dimensions of the integrated circuit manufacturing process continue to shrink, the requirements for overlay accuracy in advanced node manufacturing processes are becoming more and more stringent. How to measure the overlay error to improve the overlay accuracy is a huge challenge facing the photolithography process. At present, it is possible to obtain an overlay mark image, set an overlay recognition area, obtain the image information inside the area, and calculate the overlay error based on the image information. However, in actual processes, the image quality of the overlay mark image is easily affected by process changes, which is not conducive to accurately calculating the overlay error. Summary of the invention

[0004] In order to solve the above technical problems, the embodiments of the present application provide a method and device for processing an overlay mark image to improve the calculation accuracy of the overlay error.

[0005] The present application provides a method for processing an overlay mark image, the method comprising:

[0006] Acquire an overlay logo image, wherein the overlay logo image includes a first graphic and a second graphic, and the first graphic and the second graphic are arranged to overlap;

[0007] Identify the overlay mark image to determine a first area where the first graphic is located and a second area where the second graphic is located;

[0008] When the first region and the second region meet the image contrast condition, performing random error correction processing on the first region and / or the second region to reduce noise in the first region and / or the second region;

[0009] An overlay error between the first graphic and the second graphic is calculated based on the corrected overlay mark image.

[0010] Optionally, the contrast condition includes that the image contrast of the first area is greater than or equal to a first contrast threshold, and the image contrast of the second area is greater than or equal to a second contrast threshold, and before performing random error correction processing on the first area and / or the second area, the method further includes:

[0011] If the image contrast of the first area is less than the first contrast threshold, performing contrast enhancement processing on the first area; and / or,

[0012] If the image contrast of the second area is less than the second contrast threshold, contrast enhancement processing is performed on the second area.

[0013] Optionally, the first contrast threshold and the second contrast threshold are 10%.

[0014] Optionally, identifying the overlay mark image to determine a first area where the first graphic is located and a second area where the second graphic is located includes: segmenting the overlay mark image to obtain a first area where the first graphic is located and a second area where the second graphic is located;

[0015] After the random error correction processing is performed on the first area and / or the second area, the method further includes: splicing the first area and the second area to obtain a corrected overlay mark image.

[0016] Optionally, the overlay mark image is of a box-type overlay type, a line-type overlay type or an advanced image measurement type.

[0017] Optionally, the overlay error between the first overlay pattern and the second overlay pattern is a gravity center offset between the first overlay pattern and the second overlay pattern.

[0018] The present application also provides an overlay mark image processing device, the device comprising:

[0019] An image acquisition unit, used for acquiring an overlay mark image, wherein the overlay mark image includes a first graphic and a second graphic, wherein the first graphic and the second graphic are overlaid;

[0020] An area acquisition unit, used to identify the overlay mark image and determine a first area where the first graphic is located and a second area where the second graphic is located;

[0021] a correction processing unit, configured to perform random error correction processing on the first region and / or the second region to reduce noise in the first region and / or the second region when the first region and the second region meet an image contrast condition;

[0022] The error calculation unit is used to calculate the overlay error between the first graphic and the second graphic based on the corrected overlay mark image.

[0023] Optionally, the contrast condition includes that the image contrast of the first area is greater than or equal to a first contrast threshold, and the image contrast of the second area is greater than or equal to a second contrast threshold, and the device further includes:

[0024] A contrast enhancement processing unit is used for, before performing random error correction processing on the first area and / or the second area:

[0025] If the image contrast of the first area is less than the first contrast threshold, contrast enhancement processing is performed on the first area; and / or if the image contrast of the second area is less than the second contrast threshold, contrast enhancement processing is performed on the second area.

[0026] Optionally, the first contrast threshold and the second contrast threshold are 10%.

[0027] Optionally, the region acquisition unit is specifically used to: segment the overlay mark image to obtain a first region where the first graphic is located and a second region where the second graphic is located;

[0028] The device further includes: a splicing unit, which is used to splice the first area and the second area to obtain a corrected overlay mark image after performing random error correction processing on the first area and / or the second area.

[0029] Optionally, the overlay mark image is of a box-type overlay type, a line-type overlay type or an advanced image measurement type.

[0030] Optionally, the overlay error between the first overlay pattern and the second overlay pattern is a gravity center offset between the first overlay pattern and the second overlay pattern.

[0031] The embodiment of the present application provides a method and device for processing an overlay mark image, wherein the overlay mark image may include a first graphic and a second graphic, wherein the first graphic and the second graphic are arranged to overlap, the overlay mark image is identified, a first area where the first graphic is located and a second area where the second graphic is located are determined, and when the first area and the second area meet the image contrast condition, the first area and / or the second area are subjected to random error correction processing to reduce the noise in the first area and / or the second area, and the overlay error between the first graphic and the second graphic is calculated based on the corrected overlay mark image. Since the first area and / or the second area are subjected to random error correction processing, the noise therein is suppressed, which is conducive to accurate edge recognition of the first graphic and the second graphic, thereby improving the calculation accuracy of the overlay error, improving the use efficiency of the overlay machine, and improving the tolerance to process fluctuations and process errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0033] Figure 1 A flowchart of an overlay mark image processing method provided in an embodiment of the present application;

[0034] Figure 2 A schematic diagram of an overlay accuracy measurement mark in an embodiment of the present application;

[0035] Figure 3 A schematic diagram of an overlay logo image in an embodiment of the present application;

[0036] Figure 4 A schematic diagram of the second region after image contrast enhancement in an embodiment of the present application;

[0037] Figure 5 right Figure 4 A schematic diagram of the second area after the second area in FIG. is corrected;

[0038] Figure 6 is a schematic diagram of a modified overlay mark image in an embodiment of the present application;

[0039] Figure 7 A schematic diagram of an overlay measurement area in an embodiment of the present application;

[0040] Figure 8 A structural block diagram of an overlay mark image processing device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0041] In the manufacturing of integrated circuits, the first layer of graphics and the second layer of graphics can be overlapped together, which is called overlay. However, in reality, due to the existence of systematic errors and accidental errors, the positions of the first layer of graphics and the second layer of graphics often deviate, that is, there is an overlay error. As the critical dimensions of the integrated circuit manufacturing process continue to shrink, the requirements for overlay accuracy in advanced node manufacturing processes are becoming more and more stringent. How to measure the overlay error to improve the overlay accuracy is a huge challenge facing the photolithography process. At present, it is possible to obtain an overlay identification image, set an overlay identification area, obtain the image information inside the area, and calculate the overlay error based on the image information.

[0042] In actual operation, the first layer of patterns can be exposed on the silicon wafer, and then the first layer of patterns can be used to perform the first process of the silicon wafer. After the first process is completed, the mask can be replaced, and then the second layer of patterns can be exposed on the silicon wafer. In this way, the first layer of patterns and the second layer of patterns exist on the silicon wafer at the same time, and then the second layer of patterns can be used to perform the second process of the silicon wafer. The objects of the first process and the second process can be different film layers. Of course, after exposing the second layer of patterns on the silicon wafer, the silicon wafer can also be photographed to obtain an overlay mark image including the first layer of patterns and the second layer of patterns. By analyzing the overlay mark image, the positions of the first layer of patterns and the second layer of patterns can be analyzed.

[0043] However, the analysis of the positions of the first and second layers of graphics is often affected by the image quality of the overlay mark image, such as affecting the contrast of the overlay mark image, making the noise or round edge roughness of the overlay mark image larger, and being affected by the process to make the overlay structure tilted or the left and right edge sidewall angles asymmetric, which affects the calculation of the overlay error when the image quality is poor. The image quality of the overlay mark image is easily affected by process changes, which is not conducive to the accurate calculation of the overlay error.

[0044] After research, the inventor found that since the first figure and the second figure are located in different layers of the wafer, there is a certain thickness difference between the two. When the wafer is photographed to obtain an overlay mark image, interference, focusing position, etc. will affect the quality of the overlay mark image, making the obtained overlay mark image have low clarity, which is not conducive to the analysis of the first figure and the second figure. For example, the presence of noise and low contrast in the overlay mark image is not conducive to extracting the graphic features of the first figure and the second figure, thereby affecting the calculation of the overlay error.

[0045] In the prior art, image-based overlay mark recognition is often affected by the contrast of the graphics. When the image clarity decreases, the existing equipment often reports that it cannot be recognized or the result measurement error is very large when recognizing the overlay mark. Therefore, when dealing with such problems, engineers can only seek to change the type or thickness of the coating film, or perform measurements during the etching stage, or replace / upgrade the overlay measurement equipment to achieve zoom measurement to improve the contrast of the overlay mark image and improve the signal-to-noise ratio. However, changing the film type or thickness is often unacceptable for the process. Measurement during the etching stage can only result in the problem wafer being scrapped and cannot be reworked. Replacing / upgrading the overlay measurement equipment to achieve zoom measurement will double the measurement time and increase the measurement cost.

[0046] Based on the above technical problems, the embodiment of the present application provides a method and device for processing an overlay mark image, wherein the overlay mark image may include a first graphic and a second graphic, the first graphic and the second graphic are arranged to overlap, the overlay mark image is identified, and the first area where the first graphic is located and the second area where the second graphic is located are determined. When the first area and the second area meet the image contrast condition, the first area and / or the second area are subjected to random error correction processing to reduce the noise in the first area and / or the second area, and the overlay error between the first graphic and the second graphic is calculated based on the corrected overlay mark image. Since the first area and / or the second area are subjected to random error correction processing, the noise therein is suppressed, which is conducive to accurate edge recognition of the first graphic and the second graphic, thereby improving the calculation accuracy of the overlay error, improving the utilization efficiency of the overlay machine, and improving the tolerance to process fluctuations and process errors.

[0047] The specific implementation of the overlay mark image processing method and device in the embodiment of the present application is described in detail below with reference to the accompanying drawings by way of examples.

[0048] refer to Figure 1 FIG. 1 is a flowchart of a method for processing an overlay mark image provided by an embodiment of the present application. The method may include the following steps:

[0049] S101, obtaining an overlay mark image.

[0050] In an embodiment of the present application, an overlay mark image can be obtained, and the overlay mark image can be obtained by photographing a wafer, and a first pattern and a second pattern can be formed on the wafer, and the overlay mark image obtained by photographing the wafer can also include the first pattern and the second pattern. Specifically, the wafer may include a first etching layer and a second etching layer, and the first pattern can be formed in the first etching layer by processing the first etching layer, and the second etching layer is located on the first etching layer. The second pattern can be formed in the photoresist layer on the second etching layer by exposure, so that when the overlay error between the first pattern and the second pattern is large, re-exposure is performed, and the measurement is set in the post-lithography measurement stage before the etching stage, so as to reduce the scrap rate caused by etching the wafer under inaccurate exposure patterns.

[0051] The first graphic and the second graphic can be set to overlap to form an overlay precision measurement mark graphic. Figure 2 FIG. 1 is a schematic diagram of an overlay accuracy measurement mark in an embodiment of the present application, wherein Figure 2 A is a box-in-box type logo. Figure 2 B is a bar-in-bar logo. Figure 2 C is an advanced imaging metrology (AIM). The dark outer frame structure of the above three types of logos is the first graphic, which is also produced by the previous layer process, and the light inner frame structure is produced by the current layer process. Among them, the AIM type logo is a grating structure, and the grating structure composed of multiple lines has a relatively high measurement signal-to-noise ratio. In addition, the overlay precision measurement logo pattern in the embodiment of the present application can also be other independently designed periodic line structures, and more substructures can be subdivided in these structures, which will not be illustrated one by one here.

[0052] The embodiment of the present application can analyze the low-contrast and high-noise overlay mark image, and the measurement process can be set in the post-lithography measurement stage before the etching stage, thereby reducing the scrap rate caused by etching the wafer under inaccurate exposure patterns. The following will take the AIM structure as an example, and its overall size is in the range of 20 microns to 50 microns. Figure 3 FIG. 1 is a schematic diagram of an overlay mark image in an embodiment of the present application, wherein four overlay mark structures 11, 12, 13, and 14 with higher contrast of the outer image are located in the first, second, third, and fourth quadrants, respectively, to form a first figure. Figure 3 As shown in A, the four overlay marking structures 21, 22, 23, and 24 with lower contrast of the inner image are located in the first, second, third, and fourth quadrants, respectively, forming the second figure. Figure 3 As shown in B, when the first figure and the second figure are accurately overlaid, the centers of gravity of the first figure and the second figure coincide. Figure 3In the present invention, the overlay mark image has large noise and contrast difference, which makes it difficult to reflect obvious graphic features from the image, and is not conducive to the accurate and automatic measurement of overlay error using existing methods.

[0053] S102, identifying the overlay mark image, and determining a first area where the first graphic is located and a second area where the second graphic is located.

[0054] After acquiring the overlay mark image, the overlay mark image can be identified to determine the first area 10 where the first graphics 11, 12, 13, 14 are located and the second area 20 where the second graphics 21, 22, 23, 24 are located. Figure 3 As shown. The recognition of the overlay logo image can be realized based on the type of the overlay logo image. The first and second graphics in different types of overlay logo images have different relative positions, and the first and second areas in corresponding different types of overlay logo images also have different relative positions; the recognition of the overlay logo image can also be realized based on the contrast, pixel value and other features of the first and second graphics. Usually, the first area where the first graphic is located has a regular pixel value change, and the second area where the second graphic is located has a regular pixel value change; the recognition of the overlay logo image can be realized based on the user's instructions, for example, the recognition of the overlay logo image is realized based on the user's instructions to select the first area and the second area.

[0055] After the first area 10 and the second area 20 are identified, if the contrast between the first area 10 and the second area 20 is low, the contrast of the first area 10 and the second area 20 may be enhanced. Specifically, when the first area and the second area do not meet the image contrast condition, the contrast of the first area and the second area may be enhanced, wherein the contrast condition may include that the image contrast of the first area is greater than or equal to a first contrast threshold, and the image contrast of the second area is greater than or equal to a second contrast threshold, then if the image contrast of the first area is less than the first contrast threshold, the contrast enhancement process may be performed on the first area, and / or, if the image contrast of the second area is less than the second contrast threshold, the contrast enhancement process may be performed on the second area, thereby helping to eliminate the measurement influence caused by the data rounding error under the low contrast pixel.

[0056] Among them, the image contrast of the first area and the second area can be calculated in a variety of ways. For example, the image contrast can be the ratio of the difference between the maximum pixel value and the minimum pixel value of the image to the sum of the maximum pixel value and the minimum pixel value. For example, in the embodiment of the present application, the maximum pixel value of the first area 10 is 220, and the minimum pixel value is 140, then the image contrast is 0.22 (22%), and the maximum pixel value of the second area 20 is 240, and the minimum pixel value is 210, then the image contrast is 0.067 (6.7%), and its image contrast is relatively small, which is not conducive to the measurement of the overlay mark. The first contrast threshold and the second contrast threshold can be the same or different. For example, the first contrast threshold and the second contrast threshold can both be 10%, or can both be other values, for example, both can be 50%.

[0057] The contrast enhancement processing of the first area and the second area may have an image contrast magnification, for example, the maximum value may be set to 255, the minimum value may be set to 0, and the pixel value of the first area and / or the second area may be adjusted to achieve an enhancement of the image contrast of the first area and / or the second area. As an example, in the embodiment of the present application, the first contrast threshold and the second contrast threshold may be set to 10%, then in the specific operation, only the image contrast of the second area 20 is enhanced, refer to Figure 4 As shown, it is a schematic diagram of the second area after image contrast enhancement in an embodiment of the present application, wherein the overlay identification structures 21, 22, 23, and 24 are respectively adjusted to overlay identification structures 201, 202, 203, and 204, and the second area 20 is adjusted to the second area 200.

[0058] Of course, the above contrast enhancement process for the first region and / or the second region is performed when the contrast of the first region and / or the second region is low. If the contrast of the first region and / or the second region is high, this step may not be performed.

[0059] S103, when the first region and the second region meet the image contrast condition, perform random error correction processing on the first region and / or the second region to reduce noise in the first region and / or the second region.

[0060] After the first area 10 and the second area 20 are identified, when the first area and the second area meet the image contrast condition, it can be considered that the pixel features of the first area and the second area are easy to identify, and then the first area 10 and / or the second area 20 can be subjected to random error correction processing to reduce the noise of the first area 10 and / or the second area 20. The random error correction processing can be implemented by image processing technology, and the image processing technology can adopt a spatial domain processing model or a frequency domain processing model. As an example, the embodiment of the present application can adopt a spatial domain processing model, and the model parameters and processing levels can be set in advance, wherein the processing level can not exceed 5 layers, in order to obtain a better image correction effect.

[0061] When performing random error correction processing on the first area 10 and / or the second area 20, relevant parameters can be used for the mutually symmetrical overlay mark structures. For example, the same parameters are used for the overlay mark structures 201 and 203, and the A parameters and B parameters are used in the X direction and the Y direction respectively. Symmetric parameters are used for the overlay mark structures 202 and 204, that is, the B parameters and A parameters are used in the X direction and the Y direction respectively, to ensure symmetry and consistency during the processing. In the above random error correction processing, the size of the overlay mark image corresponding to the overlay mark analyzed based on the same parameters is consistent, and the magnification of the overlay measurement machine used is also consistent.

[0062] In the embodiment of the present application, random error correction processing can be performed only on the second area, referring to Figure 5 As shown, for Figure 4 Schematic diagram of a second region after the second region in the figure is corrected, wherein the corrected second region 210 includes the overlay identification structures 211, 212, 213, 214 obtained after the overlay identification structures 201, 202, 203, 204 are corrected, and Figure 4 Compared with the second area 200, Figure 5 The smooth characteristic feature of the second area 210 is enhanced, and the feature of low contrast on the outside and high contrast on the inside of the overlay mark is retained.

[0063] The above contrast enhancement processing and random error correction processing can be performed on the first area and the second area at the same time, or only on the first area, or only on the second area. If only the first area or the second area is processed, the first area and the second area can be separated to achieve separate processing of the two. After processing, the areas can be spliced ​​to obtain a corrected overlay mark image, wherein the splicing method is completely opposite to the image segmentation technology to ensure the precise consistency of the image position. Figure 6As shown, it is a schematic diagram of the corrected overlay logo image in the embodiment of the present application, wherein the overlay logo image is obtained by splicing the corrected second area (including the corrected overlay logo structures 211, 212, 213, 214) and the original first area (including the overlay logo structures 11, 12, 13, 14), wherein the image contrast of the second area is significantly enhanced, and the image quality of the overlay logo image is significantly improved.

[0064] S104, calculating the overlay error between the first graphic and the second graphic based on the corrected overlay mark image.

[0065] In the corrected overlay mark image, the noise is suppressed and the image contrast is improved, so the image quality is high. The overlay error between the first figure and the second figure calculated based on the corrected overlay mark image also has higher accuracy and lower requirements for the original overlay mark image, which greatly expands the scope of application of image-based overlay measurement. The overlay error between the first figure and the second figure can be expressed in many forms and calculated in many ways. The following will take the center of gravity offset of the first figure and the second figure as an example of the overlay error.

[0066] Specifically, the center coordinates of the first figure and the center coordinates of the second figure can be calculated, and the difference between the center coordinates of the first figure and the center coordinates of the second figure is used as the center of gravity offset of the first figure and the second figure. The center coordinates of the first figure can be determined according to the change period and symmetry of the overlay mark structure of the four quadrants, and the center coordinates of the second figure can be determined according to the change period and symmetry of the overlay mark structure of the four quadrants.

[0067] When calculating the center coordinates of the first figure and the center coordinates of the second figure, all features of the first figure and the second figure can be considered, and appropriate overlay measurement areas can be set in the first figure and the second figure. The overlay measurement area of ​​the first figure is smaller than the first area, and the overlay area of ​​the second figure is smaller than the second area. The overlay error is calculated along the overlay mark direction within the overlay measurement area to reduce the amount of information that needs to be processed. At the same time, since the contrast between the edges of the first figure and the second figure is low, appropriately selecting the overlay measurement area can avoid using data from areas with lower image quality, thereby reducing the amount of data calculation and improving the calculation accuracy.

[0068] refer to Figure 7As shown, it is a schematic diagram of an overlay measurement area in an embodiment of the present application. The overlay measurement area 61 of the first figure may include sub-areas 611, 612, 613, and 614 in four quadrants, and the sub-areas may be located in the middle of the corresponding overlay identification structures 11, 12, 13, and 14. The overlay measurement area 62 of the second figure may include sub-areas 621, 622, 623, and 624 in four quadrants, and the sub-areas may be located in the middle of the corresponding overlay identification structures 211, 212, 213, and 214.

[0069] In the selection of the overlay measurement area, the symmetry of the graphics in the overlay measurement area can be considered, wherein the first graphic is partially symmetrical in the first quadrant and the third quadrant, and partially symmetrical in the second quadrant and the fourth quadrant, and the second graphic is partially symmetrical in the first quadrant and the third quadrant, and partially symmetrical in the second quadrant and the fourth quadrant, for example, 611 and 613 are symmetrical, and 612 and 614 are symmetrical. The relative positions of the first graphic and the second graphic in the overlay measurement area of ​​the same quadrant are the same, for example, the relative positions of 611 and 621 are the same, and the areas and shapes of the sub-areas of each overlay measurement area can be consistent.

[0070] refer to Figure 7 As shown, if the first figure is longitudinal stripes and centrally symmetrical in the first and third quadrants, the central coordinates of the first figure in the horizontal direction (X-axis central coordinates) can be determined according to the horizontal pixel variation law of the overlay measurement areas 611 and 613. If the first figure is longitudinal stripes and centrally symmetrical in the second and fourth quadrants, the central coordinates of the first figure in the vertical direction (Y-axis coordinates) can be determined according to the vertical pixel variation law of the overlay measurement areas 612 and 614. The central coordinates of the first figure are determined based on the horizontal and vertical central coordinates of the first figure. Similarly, if the second figure is longitudinal stripes and centrally symmetrical in the first and third quadrants, the central coordinates of the second figure in the horizontal direction (X-axis central coordinates) can be determined according to the horizontal pixel variation of the overlay measurement areas 621 and 623. If the second figure is longitudinal stripes and centrally symmetrical in the second and fourth quadrants, the central coordinates of the second figure in the vertical direction (Y-axis central coordinates) can be determined according to the vertical pixel variation of the overlay measurement areas 622 and 624. The central coordinates of the second figure are determined based on the horizontal and vertical central coordinates of the second figure.

[0071] Based on the above results, the center coordinates of the first figure and the center coordinates of the second figure are subtracted to obtain the overlay error of the first figure and the second figure. In the embodiment of the present application, the overlay error of the first figure and the second figure in the horizontal direction is -6.7nm, and the overlay error in the vertical direction is 9nm.

[0072] The embodiment of the present application provides a method for processing an overlay mark image, wherein the overlay mark image may include a first graphic and a second graphic, wherein the first graphic and the second graphic are arranged to overlap, the overlay mark image is identified, a first region where the first graphic is located and a second region where the second graphic is located are determined, and when the first region and the second region meet the image contrast condition, the first region and / or the second region are subjected to random error correction processing to reduce the noise in the first region and / or the second region, and the overlay error between the first graphic and the second graphic is calculated based on the corrected overlay mark image. Since the first region and / or the second region are subjected to random error correction processing, the noise therein is suppressed, which is conducive to accurate edge recognition of the first graphic and the second graphic, thereby improving the calculation accuracy of the overlay error, improving the utilization efficiency of the overlay machine, and improving the tolerance to process fluctuations and process errors.

[0073] Based on the above-mentioned overlay mark image processing method, the present application embodiment also provides an overlay mark image processing device, referring to Figure 8 As shown, it is a structural block diagram of an overlay mark image processing device provided in an embodiment of the present application, and the device may include:

[0074] An image acquisition unit 110 is used to acquire an overlay mark image, wherein the overlay mark image includes a first graphic and a second graphic, and the first graphic and the second graphic are arranged to overlap;

[0075] An area acquisition unit 120 is used to identify the overlay mark image and determine a first area where the first graphic is located and a second area where the second graphic is located;

[0076] A correction processing unit 130, configured to perform random error correction processing on the first region and / or the second region to reduce noise in the first region and / or the second region when the first region and the second region meet an image contrast condition;

[0077] The error calculation unit 140 is used to calculate the overlay error between the first graphic and the second graphic based on the corrected overlay mark image.

[0078] Optionally, the contrast condition includes that the image contrast of the first area is greater than or equal to a first contrast threshold, and the image contrast of the second area is greater than or equal to a second contrast threshold, and the device further includes:

[0079] A contrast enhancement processing unit is used for, before performing random error correction processing on the first area and / or the second area:

[0080] If the image contrast of the first area is less than the first contrast threshold, contrast enhancement processing is performed on the first area; and / or if the image contrast of the second area is less than the second contrast threshold, contrast enhancement processing is performed on the second area.

[0081] Optionally, the first contrast threshold and the second contrast threshold are 10%.

[0082] Optionally, the region acquisition unit is specifically used to: segment the overlay mark image to obtain a first region where the first graphic is located and a second region where the second graphic is located;

[0083] The device further includes: a splicing unit, which is used to splice the first area and the second area to obtain a corrected overlay mark image after performing random error correction processing on the first area and / or the second area.

[0084] Optionally, the overlay mark image is of a box-type overlay type, a line-type overlay type or an advanced image measurement type.

[0085] Optionally, the overlay error between the first overlay pattern and the second overlay pattern is a gravity center offset between the first overlay pattern and the second overlay pattern.

[0086] The embodiment of the present application provides an overlay mark image processing device, the overlay mark image may include a first graphic and a second graphic, the first graphic and the second graphic are arranged to overlap, the overlay mark image is identified, the first area where the first graphic is located and the second area where the second graphic is located are determined, and when the first area and the second area meet the image contrast condition, the first area and / or the second area are subjected to random error correction processing to reduce the noise in the first area and / or the second area, and the overlay error between the first graphic and the second graphic is calculated based on the corrected overlay mark image. Since the first area and / or the second area are subjected to random error correction processing, the noise therein is suppressed, which is conducive to accurate edge recognition of the first graphic and the second graphic, thereby improving the calculation accuracy of the overlay error, improving the use efficiency of the overlay machine, and improving the tolerance to process fluctuations and process errors.

[0087] The "first" in the names of "first graphic" and "first area" mentioned in the embodiments of the present application is only used as a name identifier and does not mean the first in order. The same rule applies to "second" and so on.

[0088] Through the description of the above implementation methods, it can be known that those skilled in the art can clearly understand that all or part of the steps in the above-mentioned embodiment method can be implemented by means of software plus a general hardware platform. Based on such an understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a storage medium, such as a read-only memory (ROM) / RAM, a magnetic disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network communication device such as a router) to execute the methods described in each embodiment of the present application or some parts of the embodiments.

[0089] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The equipment and system embodiments described above are merely schematic, in which the modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0090] The above is only a preferred embodiment of the present application and is not intended to limit the protection scope of the present application. It should be noted that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the present application, and these improvements and modifications should also be regarded as the protection scope of the present application.

Claims

1. A method for processing an overlay mark image, characterized in that: The method comprises: Acquire an overlay mark image, wherein the overlay mark image includes a first graphic and a second graphic, and the first graphic and the second graphic are arranged to overlap; Identify the overlay mark image to determine a first area where the first graphic is located and a second area where the second graphic is located; When the first area and the second area meet an image contrast condition, performing random error correction processing on the first area and / or the second area to reduce noise in the first area and / or the second area; the contrast condition includes that the image contrast of the first area is greater than or equal to a first contrast threshold, and the image contrast of the second area is greater than or equal to a second contrast threshold; An overlay error between the first graphic and the second graphic is calculated based on the corrected overlay mark image.

2. The method according to claim 1, characterized in that Before performing random error correction processing on the first area and / or the second area, the method further includes: If the image contrast of the first area is less than the first contrast threshold, performing contrast enhancement processing on the first area; and / or, If the image contrast of the second area is less than the second contrast threshold, contrast enhancement processing is performed on the second area.

3. The method according to claim 2, characterized in that The first contrast threshold and the second contrast threshold are 10%.

4. The method according to any one of claims 1 to 3, characterized in that: Identifying the overlay mark image to determine a first area where the first graphic is located and a second area where the second graphic is located, including: segmenting the overlay mark image to obtain a first area where the first graphic is located and a second area where the second graphic is located; After the random error correction processing is performed on the first area and / or the second area, the method further includes: splicing the first area and the second area to obtain a corrected overlay mark image.

5. The method according to any one of claims 1 to 3, characterized in that: The overlay mark image is of a box-type overlay type, a line-type overlay type or an advanced image measurement type.

6. The method according to any one of claims 1 to 3, characterized in that: The overlay error between the first graphic and the second graphic is an offset of the center of gravity of the first graphic and the second graphic.

7. An overlay mark image processing device, characterized in that: The device comprises: An image acquisition unit, used for acquiring an overlay mark image, wherein the overlay mark image includes a first graphic and a second graphic, wherein the first graphic and the second graphic are overlaid; An area acquisition unit, used to identify the overlay mark image and determine a first area where the first graphic is located and a second area where the second graphic is located; a correction processing unit, configured to perform random error correction processing on the first area and / or the second area to reduce noise in the first area and / or the second area when the first area and the second area meet an image contrast condition; the contrast condition includes that the image contrast of the first area is greater than or equal to a first contrast threshold, and the image contrast of the second area is greater than or equal to a second contrast threshold; The error calculation unit is used to calculate the overlay error between the first graphic and the second graphic based on the corrected overlay mark image.

8. The device according to claim 7, characterized in that The device also includes: A contrast enhancement processing unit is used for, before performing random error correction processing on the first area and / or the second area: If the image contrast of the first area is less than the first contrast threshold, contrast enhancement processing is performed on the first area; and / or if the image contrast of the second area is less than the second contrast threshold, contrast enhancement processing is performed on the second area.

9. The device according to claim 7 or 8, characterized in that The region acquisition unit is specifically used to: segment the overlay mark image to obtain a first region where the first graphic is located and a second region where the second graphic is located; The device further includes: a splicing unit, which is used to splice the first area and the second area to obtain a corrected overlay mark image after performing random error correction processing on the first area and / or the second area.

10. The device according to claim 7 or 8, characterized in that The overlay error between the first graphic and the second graphic is an offset of the center of gravity of the first graphic and the second graphic.

Images