Image correction method and apparatus

Abstract

The present invention provides an image correction method and device, which includes the steps of: centering a design layout of a sample to be detected and an SEM image obtained by a scanning electron microscope; determining keypoint pairs based on the design layout and image cells in the SEM image; correcting the SEM image based on the keypoint pairs to obtain a corrected SEM image; determining a distortion amount based on the design layout and the corrected SEM image; and determining to end the correction of the SEM image when the distortion amount is smaller than a predetermined threshold. This allows the keypoint pairs to be determined based on the design layout and image cells in the SEM image, and the SEM image to be corrected based on the keypoint pairs, so that the image cells in the SEM image of the sample to be detected and the image cells in the design layout can be matched as much as possible, making the correction of the SEM image more accurate and reliable, and improving the accuracy and reliability of the SEM image correction.

Description

[Technical Field]

[0001] The present invention relates to the field of semiconductor technology, and more particularly to an image correction method and apparatus. [Background technology]

[0002] With the development of integrated circuits, electron beam detection technology is also constantly improving. Secondary electron images can usually be collected using electron beam detection and measurement devices. However, during the scanning process using electron beam detection and measurement devices, the electron gun is susceptible to factors such as mechanical vibration and surface charge accumulation effects. This can cause distortions in the resulting scanning electron microscope (SEM) images, which require correction.

[0003] In related art, when correcting SEM images, typically, an SEM image of a standard sample is first taken, and the distortion and magnification difference are calculated based on the SEM image. The results are then used to correct the SEM image of the target sample, which is highly dependent on the condition of the standard sample. Because the SEM image correction is completed on a non-real sample, there may be differences between the material and surface condition of the real sample and the standard sample. This may result in inconsistencies between the distortion of the real sample and that of the standard sample, resulting in poor correction effectiveness and accuracy. Therefore, how to improve the accuracy of SEM image correction is important. Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional techniques, when correcting SEM images, there may be differences between the material and surface condition of the actual sample and the standard sample, so the amount of distortion of the actual sample to be detected may not completely match the amount of distortion of the standard sample, resulting in low correction effectiveness and low accuracy.In response to this situation, the following technical means are provided. [Means for solving the problem]

[0005] An image correction method according to a first aspect of the present invention includes the steps of: centering a design layout of a sample to be detected with an SEM image taken by a scanning electron microscope; determining keypoint pairs based on the design layout and image cells in the SEM image; correcting the SEM image based on the keypoint pairs to obtain a corrected SEM image; determining an amount of distortion based on the design layout and the corrected SEM image; and deciding to terminate correction of the SEM image if the amount of distortion is smaller than a predetermined threshold.

[0006] Preferably, after the step of determining the amount of distortion based on the design layout and the corrected SEM image, if the amount of distortion is equal to or greater than a predetermined threshold, the method further includes a step of returning to and executing the step of determining key point pairs based on the design layout and the corrected SEM image.

[0007] Preferably, the step of determining keypoint pairs based on image cells in the design layout and the SEM image includes the steps of: when the geometric centers of the design layout and the SEM image are aligned, establishing a Cartesian coordinate system O-XY with the geometric center as the coordinate origin O; selecting at least one image cell in the SEM image that is periodically shifted with respect to the design layout in the XY plane as a first image cell; selecting a second image cell from the design layout at a position corresponding to the first image cell; and selecting one coordinate point at the same position in the first image cell and the second image cell as a keypoint pair.

[0008] Preferably, the step of selecting at least one image cell in the SEM image that is period-shifted relative to the design layout in the XY plane as the first image cell includes the step of selecting at least one image cell in the SEM image that is period-shifted relative to the design layout in a first direction in the XY plane as the first image cell, and the step of selecting at least one image cell in the SEM image that is period-shifted relative to the design layout in a second direction in the XY plane as the first image cell.

[0009] Preferably, the step of correcting the SEM image based on the keypoint pairs to obtain a corrected SEM image includes the steps of: determining correction parameters based on the keypoint pairs, the correction parameters including at least one of a rotation parameter, a scaling parameter, and a translation parameter; and processing the SEM image in accordance with the correction parameters to determine a corrected SEM image.

[0010] Preferably, the step of determining the amount of distortion based on the design layout and the corrected SEM image includes the steps of determining a first first order origin moment coordinate for each first image cell of the corrected SEM image and a second first order origin moment coordinate for each second image cell of the design layout, and processing the corresponding first order origin moment coordinates and second first order origin moment coordinates of the corrected SEM image and the design layout to determine the amount of distortion.

[0011] Preferably, the step of processing the corresponding first and second first-order origin moment coordinates of the corrected SEM image and the design layout to determine the amount of distortion includes the steps of: dividing the corrected SEM image and the design layout in the same manner to obtain corresponding first sub-images and second sub-images; and averaging the first first-order origin moment coordinates of first image cells included in each of the first sub-images and the second first-order origin moment coordinates of second image cells included in each of the second sub-images to determine the amount of distortion between each of the first sub-images and the corresponding second sub-images.

[0012] Preferably, the step of deciding to terminate the correction of the SEM image includes the steps of: determining the difference between two adjacent distortion amounts when multiple distortion amounts are acquired; and deciding to terminate the correction of the SEM image when any of the differences is a negative number.

[0013] An image correction device according to a second aspect of the present invention includes an alignment module that aligns the center of a design layout of a sample to be detected with an SEM image taken by a scanning electron microscope; a first determination module that determines keypoint pairs based on the design layout and image cells in the SEM image; a correction module that corrects the SEM image based on the keypoint pairs to obtain a corrected SEM image; a second determination module that determines an amount of distortion based on the design layout and the corrected SEM image; and a third determination module that determines to terminate the correction of the SEM image if the amount of distortion is smaller than a predetermined threshold.

[0014] Preferably, the third determination module further returns to the step of determining keypoint pairs based on the design layout and the corrected SEM image if the distortion amount is equal to or greater than a predetermined threshold.

[0015] Preferably, the first determination module includes: an establishment unit for establishing a Cartesian coordinate system O-XY with the geometric center as a coordinate origin O when the geometric centers of the design layout and the SEM image are aligned; a first selection unit for selecting, in the XY plane, at least one image cell of the SEM image that is periodically shifted with respect to the design layout as a first image cell; a second selection unit for selecting, from the design layout, a second image cell at a position corresponding to the first image cell; and a third selection unit for selecting, as a keypoint pair, one coordinate point at the same position of the first image cell and the second image cell.

[0016] Preferably, the first selection unit specifically performs the steps of selecting at least one image cell of the SEM image that is periodically shifted relative to the design layout in a first direction in the XY plane as a first image cell, and selecting at least one image cell of the SEM image that is periodically shifted relative to the design layout in a second direction in the XY plane as a first image cell.

[0017] Preferably, the correction module specifically performs the steps of determining correction parameters including at least one of a rotation parameter, a scaling parameter, and a translation parameter based on the keypoint pairs, and processing the SEM image in accordance with the correction parameters to determine a corrected SEM image.

[0018] Preferably, the second determination module includes a first determination unit that determines first first order origin moment coordinates of each first image cell of the corrected SEM image and second first order origin moment coordinates of each second image cell of the design layout, and a processing unit that processes the corresponding first order origin moment coordinates and second first order origin moment coordinates of the corrected SEM image and the design layout to determine an amount of distortion.

[0019] Preferably, the processing unit specifically performs the steps of: dividing the corrected SEM image and the design layout in the same manner to obtain corresponding first sub-images and second sub-images; and averaging the first first-order origin moment coordinates of first image cells included in each of the first sub-images and the second first-order origin moment coordinates of second image cells included in each of the second sub-images to determine the amount of distortion between each of the first sub-images and the corresponding second sub-images.

[0020] Preferably, the third determination module specifically executes the steps of: determining the difference between two adjacent distortion amounts when multiple distortion amounts are acquired; and determining to terminate correction of the SEM image when any of the differences is a negative number.

[0021] An electronic device according to a third aspect of the present invention includes a processor and a memory in which computer program instructions are stored, When the processor executes the computer program instructions, it implements any of the image correction methods described above.

[0022] A fourth aspect of the present invention provides a computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement any one of the image correction methods described above.

[0023] As described above, the present invention provides an image correction method and apparatus, which includes the steps of: centering a design layout of a sample to be detected with an SEM image captured by a scanning electron microscope; determining keypoint pairs based on image cells in the design layout and the SEM image; correcting the SEM image based on the keypoint pairs to obtain a corrected SEM image; determining a distortion amount based on the design layout and the corrected SEM image; and determining to terminate correction of the SEM image if the distortion amount is smaller than a predetermined threshold. In this way, after centering the design layout of the sample to be detected with the SEM image, keypoint pairs are determined based on image cells in the design layout and the SEM image; and the SEM image may be corrected based on the keypoint pairs, so that the image cells in the SEM image of the sample to be detected and the image cells in the design layout can be matched as closely as possible, thereby making the determined keypoint pairs more accurate and reliable and further improving the accuracy and reliability of SEM image correction. [Brief explanation of the drawings]

[0024] In order to more clearly describe the specific embodiments of the present invention or the technical means in the prior art, the drawings necessary for describing the specific embodiments or the prior art will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative work.

[0025] [Figure 1] 2 is a flowchart of an image correction method according to an embodiment of the present invention. [Figure 2] 2 is a flowchart of an image correction method according to an embodiment of the present invention. [Figure 3] 1A and 1B are schematic diagrams of a design layout and an SEM image according to an embodiment of the present invention. [Figure 4] 1 is a schematic diagram of an image cell according to an embodiment of the present invention; [Figure 5] 1 is a structural diagram of an image correction device according to an embodiment of the present invention; [Figure 6] 1 is a structural diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] In order to clarify the above and other features and advantages of the present invention, the present invention will be further described below with reference to the drawings. It should be understood that the specific examples provided herein are for the purpose of explanation to those skilled in the art and are merely illustrative and not limiting.

[0027] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without the specific details. In other instances, well-known steps or operations are not described in detail to avoid obscuring the present invention.

[0028] The image correction method according to the embodiment of the present invention may be performed by an image correction device according to the embodiment of the present invention, which may be disposed in an electronic device.

[0029] As shown in FIG. 1, the image correction method according to the present invention includes the following steps 101 to 105.

[0030] In step 101, the design layout of the sample to be detected is centered with the image of the scanning electron microscope.

[0031] A scanning electron microscope (SEM) may scan a physical sample of interest, such as a semiconductor silicon wafer, to generate a corresponding SEM image.

[0032] There are several methods for aligning the centers of the design layout of the sample to be detected and the image captured by the scanning electron microscope. For example, the geometric centers of the design layout of the sample to be detected and the SEM image may be determined and then aligned. Alternatively, the geometric centers of the design layout and the SEM image may be determined, and then a first central pattern cell closest to the geometric center of the design layout may be determined. Then, a second central pattern cell closest to the geometric center of the SEM image may be determined, and the second central pattern cell may be aligned with the first central pattern cell. However, the present invention is not limited to this method.

[0033] In step 102, keypoint pairs are determined based on the design layout and image cells in the SEM image.

[0034] A keypoint pair may include two keypoints, for example, a first keypoint located in the SEM image and a second keypoint located in the design layout, and the position of the first keypoint in the SEM image may correspond to the position of the second keypoint in the design layout, but the present invention is not limited thereto.

[0035] Furthermore, the number of keypoint pairs may be one pair or multiple pairs, but the present invention is not limited to this.

[0036] Preferably, when centering the design layout and the SEM image, the field of view (FOV) is moved or adjusted until the image cells in the SEM image are shifted by more than one period relative to the design layout, and when the position of a first image cell 1 in the SEM image corresponds to the position of a second image cell 1 in the design layout, a keypoint pair may be determined in the first image cell 1 and the second image cell 1. For example, the geometric centers of the first image cell 1 and the second image cell 1 may be determined as a keypoint pair, and the upper right vertices of the first image cell 1 and the second image cell 1 may be determined as a set of keypoint pairs.

[0037] The period may also be understood as when, in the process of moving the FOV and observing, any first image cell of the SEM image begins to overlap with any nearest second image cell other than the second image cell of the design layout corresponding to itself, which is called one period.

[0038] For example, in the image cells shown in Figure 4, the first image cell A corresponds to the second image cell A', and when the FOV is moved horizontally and observed, when the first image cell A and the second image cell C begin to overlap, it is considered that the deviation from the design layout of the image cells in the current SEM image will soon exceed one period; alternatively, when the FOV is moved vertically and observed, when the first image cell A and the second image cell B begin to overlap, it is considered that the deviation from the design layout of the image cells in the current SEM image will soon exceed one period; however, the present invention is not limited to this.

[0039] It should be noted that the size, shape, position, etc. of the first image cell and the second image cell in FIG. 4 are merely illustrative and do not limit the first image cell and the second image cell in the embodiment of the present invention.

[0040] As can be understood, the actual detection target sample in the present invention is obtained based on the design layout, and through strict photomask and lithography manufacturing processes, the image cells in the SEM image of the detection target sample can be made to match the image cells in the design layout as much as possible. Therefore, in the embodiment of the present invention, the design layout is used as the basis for SEM image correction, and the SEM image correction process is obtained based on the corresponding design layout, which subsequently provides conditions for improving the accuracy of SEM image correction.

[0041] In step 103, the SEM image is corrected based on the keypoint pairs to obtain a corrected SEM image.

[0042] After determining the keypoint pairs, there are several methods for correcting the SEM image based on the keypoint pairs. For example, each set of keypoint pairs may be processed to determine correction parameters corresponding to each set of keypoint pairs, and then the SEM image may be corrected using the correction parameters to determine a corrected SEM image, but the present invention is not limited thereto.

[0043] In step 104, the amount of distortion is determined based on the design layout and the corrected SEM image.

[0044] After the corrected SEM image is acquired, the amount of distortion may be further determined based on a first image cell of the corrected SEM image and a second image cell of the design layout.

[0045] Preferably, a first first order origin moment coordinate for each first image cell of the corrected SEM image and a second first order origin moment coordinate for each second image cell of the design layout may be determined, and then the corresponding first order origin moment coordinates and second order origin moment coordinates of the corrected SEM image and the design layout may be processed to determine the amount of distortion.

[0046] There are multiple ways to determine the first primary origin moment coordinate and the second primary origin moment coordinate, for example, they may be determined by the primary origin moment or by each coordinate point of the image cell, but the present invention is not limited to this.

[0047] In addition, there may be multiple methods for processing the first and second first-order origin moment coordinates to determine the distortion amount. For example, the first and second first-order origin moment coordinates may be substituted into a Euclidean distance formula to determine the distortion amount from the obtained result, or the Manhattan distance formula, the cosine similarity distance formula, the Chebyshev distance formula, etc. may also be used, but the present invention is not limited thereto.

[0048] As can be understood, in the embodiment of the present invention, since the actual sample to be detected is acquired based on the design layout, when the SEM image is corrected using the design layout, the image cells in the SEM image of the sample to be detected can be matched as closely as possible with the image cells in the design layout, so that the determined keypoint pairs can be more accurate and reliable; furthermore, by processing the SEM image using more accurate and reliable keypoint pairs, inaccuracies in correction caused by differences between the sample to be detected and the standard sample can be effectively avoided, so that the correction of the SEM image can be more accurate and reliable, and the accuracy and reliability of the SEM image correction can be improved.

[0049] In step 105, if the amount of distortion is smaller than a predetermined threshold, it is determined that the correction of the SEM image is to be terminated.

[0050] The predetermined threshold value may be a preset value, and may be adjusted according to actual needs, but the present invention is not limited thereto.

[0051] Preferably, if the distortion amount is equal to or greater than the predetermined threshold, the process returns to the step of determining keypoint pairs based on the design layout and the corrected SEM image.

[0052] As can be understood, in the process of correcting an SEM image, if the distortion amount is less than a predetermined threshold, it is considered that the correction of the current SEM image is terminated. If the distortion amount is equal to or greater than the predetermined threshold, it is considered that the current SEM image still needs to be corrected. At this time, the process may return to the step of determining keypoint pairs based on the design layout and the corrected SEM image, and then determine keypoint pairs corresponding to the design layout and the corrected SEM image, and then correct the corrected SEM image based on the updated keypoint pairs to obtain a re-corrected SEM image. Then, the distortion amount is determined again based on the design layout and the re-corrected SEM image, and if the distortion amount is less than the predetermined threshold, it may be determined that the correction of the SEM image is terminated. If the distortion amount is equal to or greater than the predetermined threshold, the process may return to the step of determining keypoint pairs based on the design layout and the re-corrected SEM image and repeat the process until the distortion amount is less than the predetermined threshold.

[0053] In an embodiment of the present invention, after aligning the center of a design layout of a sample to be detected with an SEM image captured by a scanning electron microscope, keypoint pairs may be determined based on the design layout and image cells in the SEM image, the SEM image may be corrected based on the keypoint pairs to obtain a corrected SEM image, a distortion amount may be determined based on the design layout and the corrected SEM image, and if the distortion amount is smaller than a predetermined threshold, correction of the SEM image may be terminated. In this way, after aligning the center of the design layout of a sample to be detected with the SEM image, keypoint pairs may be determined based on the design layout and image cells in the SEM image, and the SEM image may be corrected based on the keypoint pairs, and the image cells in the SEM image of the sample to be detected can be matched as closely as possible with the image cells in the design layout, making the determined keypoint pairs more accurate and reliable, and further making the correction of the SEM image more accurate and reliable, thereby improving the accuracy and reliability of SEM image correction.

[0054] FIG. 2 is a flowchart of an image correction method according to an embodiment of the present invention.

[0055] As shown in FIG. 2, the image correction method may include the following steps 201 to 210.

[0056] In step 201, the center of the design layout of the sample to be detected is aligned with the center of the SEM image.

[0057] In step 202, when the geometric center of the design layout and the geometric center of the SEM image are aligned, an orthogonal coordinate system O-XY is established with the geometric center as the coordinate origin O.

[0058] For example, the geometric centers of the design layout and the SEM image may be determined, and then a Cartesian coordinate system O-XY may be established with the geometric center as the coordinate origin O. For example, the design layout may be as shown in part (a) of FIG. 3, the SEM image may be as shown in part (b) of FIG. 3, and the image after the geometric centers of the two are aligned may be as shown in part (c) of FIG. 3, but the present invention is not limited thereto.

[0059] In step 203, an image cell of the SEM image that is shifted in period by at least one with respect to the design layout is selected as a first image cell in the XY plane.

[0060] The wide field of view FOV may be moved to an edge starting from the coordinate origin O, and when the deviation of the SEM image from the design layout soon exceeds one period, the image cell in the SEM image at this time may be determined as the first image cell. The number of the first image cells may be one or more, but the present invention is not limited to this.

[0061] Preferably, at least one image cell of the SEM image that is period-shifted relative to the design layout in a first direction in the XY plane may be selected as the first image cell, and at least one image cell of the SEM image that is period-shifted relative to the design layout in a second direction in the XY plane may be selected as the first image cell.

[0062] The first direction and the second direction may be two directions that are perpendicular to each other, for example, the X-axis direction and the Y-axis direction, or any two directions that are perpendicular to each other in the XY plane, but the present invention is not limited to this.

[0063] Step 204 selects a second image cell from the design layout at a location corresponding to the first image cell.

[0064] When the geometric centers of the design layout and the SEM image are aligned, the positions of the image cells in the design layout and the SEM image correspond one-to-one, so after determining the first image cell of the SEM image, an image cell corresponding to the first image cell, i.e., the second image cell, may be selected from the design layout.

[0065] In step 205, one coordinate point at the same location in the first image cell and the second image cell is selected as a keypoint pair.

[0066] For example, the coordinate points of the center positions of the first image cell and the second image cell may be determined as a set of keypoint pairs, the coordinate points of the upper left vertices of the first image cell and the second image cell may be determined as a set of keypoint pairs, or the coordinate points of the lower right vertices of the first image cell and the second image cell may be determined as a set of keypoint pairs. For example, if the determined first image cell and second image cell are as shown in the dashed block diagram in Figure 4, the upper right vertex may be selected as a keypoint pair.

[0067] It should be noted that the above example is merely illustrative and does not limit the method of determining keypoint pairs in the embodiments of the present invention.

[0068] In step 206, correction parameters including at least one of a rotation parameter, a scaling parameter, and a translation parameter are determined based on the keypoint pairs.

[0069] After the keypoint pairs are determined, they may be processed to determine rotation, scaling, and translation parameters. Only one of the rotation, scaling, and translation parameters may be determined, or multiple parameters may be determined, such as, but not limited to, a rotation and scaling parameter, a scaling and translation parameter, or a rotation, scaling, and translation parameter.

[0070] In step 207, the SEM image is processed according to the correction parameters to determine a corrected SEM image.

[0071] There may be various methods for determining the correction parameters to process the SEM image, for example, when "+" indicates clockwise rotation and "-" indicates counterclockwise rotation, if the determined rotation parameter is +5°, the SEM image may be directly rotated 5° clockwise, but the present invention is not limited thereto.

[0072] Alternatively, the SEM image may be corrected in a matrix format. For example, if a total of three sets of keypoint pairs are currently determined, these three sets of keypoint pairs may be processed to determine corresponding correction parameters. For example, if two rotation parameters, two scaling parameters, and two translation parameters are determined, the correction parameters may be used to construct a parameter matrix, and then the parameter matrix may be multiplied by the corresponding image matrix of the SEM image to obtain a corrected SEM image.

[0073] The above example is merely illustrative and does not limit the processing method of SEM images in the embodiments of the present invention.

[0074] In step 208, the corrected SEM image and the design layout are segmented in the same manner to obtain corresponding first and second sub-images.

[0075] There are several ways to divide the corrected SEM image and the design layout. For example, the corrected SEM image and the design layout may be divided into a first sub-image and a second sub-image along the X-axis and the Y-axis with the coordinate origin as the center. Alternatively, the corrected SEM image and the design layout may be divided into a first sub-image and a second sub-image according to a period, for example, according to one period or multiple periods, but the present invention is not limited thereto.

[0076] Furthermore, the number of first sub-images and second sub-images may be one or more, but the present invention is not limited to this.

[0077] In step 209, the first first-order origin moment coordinates of the first image cells included in each first sub-image and the second first-order origin moment coordinates of the second image cells included in each second sub-image are averaged to determine the amount of distortion between each first sub-image and the corresponding second sub-image.

[0078] For example, when the first sub-image and the second sub-image are as shown in FIG. 4, after determining the first primary origin moment coordinates of each first image cell and the second primary origin moment coordinates of each second image cell, the first primary origin moment coordinates of the first sub-image (1) are added and averaged to obtain the average value as the corresponding first total primary origin moment coordinate of the first sub-image (1), and the second primary origin moment coordinates of the second sub-image (1) are averaged to determine the corresponding second total primary origin moment coordinate of the second sub-image (1), and then the distortion amount between the first sub-image (1) and the second sub-image (1) is determined based on the first total primary origin moment coordinate and the second total primary origin moment coordinate, and the distortion amount between each first sub-image and the corresponding second sub-image can be determined sequentially by referring to the above method.

[0079] It should be noted that the above example is merely illustrative and does not limit the method of determining the distortion amounts of the first and second sub-images in the embodiment of the present invention.

[0080] Preferably, after determining the distortion amount between each first sub-image and the corresponding second sub-image, the distortion amount may be output in the form of a heat map, a data table, or the like, but the present invention is not limited thereto.

[0081] In step 210, if the amount of distortion is less than a predetermined threshold, it is determined that the correction of the SEM image is to be terminated.

[0082] Preferably, when a plurality of distortion amounts are acquired, the difference between two adjacent distortion amounts is determined, and if any of the differences is a negative number, it may be determined that correction of the SEM image is to be terminated.

[0083] As can be appreciated, the process of correcting an SEM image may typically require multiple corrections, resulting in multiple distortion amounts being acquired, and these multiple distortion amounts may vary accordingly. Correction of the SEM image may be terminated when the difference between any two adjacent distortion amounts acquired is a negative number.

[0084] For example, if the distortion amount obtained by correcting an SEM image the first time is 0.3, the distortion amount obtained by correcting it the second time is 0.35, the distortion amount obtained by correcting it the third time is 0.4, and the distortion amount obtained by correcting it the fourth time is 0.25, and in this case, if the difference between the distortion amount obtained by correcting it the fourth time and the distortion amount obtained by correcting it the third time is a negative number, it may be determined to end the correction of the SEM image, but the present invention is not limited to this.

[0085] Preferably, when there are multiple first and second sub-images, when determining the difference between two adjacent distortion amounts, the difference between two adjacent distortion amounts of each first and second sub-image may be determined sequentially, and if all of them satisfy the condition, it may be decided to end the correction of the SEM image, but the present invention is not limited to this.

[0086] Preferably, after determining whether to terminate the correction of the SEM image, consideration may be given only to whether the amount of distortion is smaller than a predetermined threshold, or to whether the difference between two adjacent amounts of distortion is a negative number, or to whether the amount of distortion is smaller than a predetermined threshold and whether the difference between two adjacent amounts of distortion is a negative number, and if both conditions are met, it may be determined to terminate the correction of the SEM image, but the present invention is not limited to this.

[0087] Preferably, if the distortion amount is equal to or greater than a predetermined threshold, the process may return to the step of determining keypoint pairs based on the design layout and the corrected SEM image.

[0088] In an embodiment of the present invention, when the geometric center of the design layout of the detection sample and the SEM image are aligned, a Cartesian coordinate system O-XY is established with the geometric center as the coordinate origin O. Then, in the XY plane, at least one image cell of the SEM image that is periodically shifted from the design layout is selected as a first image cell, a second image cell at a position corresponding to the first image cell is selected from the design layout, and one coordinate point at the same position of the first image cell and the second image cell is selected as a keypoint pair. Correction parameters are then determined based on the keypoint pair, and the SEM image is processed according to the correction parameters to obtain a corrected SEM image. After that, the corrected SEM image and the design layout are divided in the same manner to obtain corresponding first sub-images and second sub-images. The first first-order origin moment coordinates of the first image cells included in each first sub-image and the second first-order origin moment coordinates of the second image cells included in each second sub-image are respectively averaged to determine the distortion amount between each first sub-image and the corresponding second sub-image. If the distortion amount is smaller than a predetermined threshold, it may be determined to terminate the correction of the SEM image. In this way, after aligning the center of the design layout of the sample to be detected with the SEM image, keypoint pairs can be determined based on the first image cells and the second image cells of the SEM image, and the SEM image can be corrected. This allows the image cells in the SEM image of the sample to be detected to match the image cells in the design layout as closely as possible, making the determined keypoint pairs more accurate and reliable, and further making the correction of the SEM image more accurate and reliable, thereby improving the accuracy and reliability of SEM image correction.

[0089] As shown in FIG. 5, the image correction device according to the present invention includes an alignment module 510, a first determination module 520, a correction module 530, a second determination module 540, and a third determination module 550.

[0090] An alignment module 510 aligns the design layout of the sample to be detected with the SEM image taken by a scanning electron microscope; a first determination module 520 determines keypoint pairs based on the design layout and image cells in the SEM image; a correction module 530 corrects the SEM image based on the keypoint pairs to obtain a corrected SEM image; a second determination module 540 determines the amount of distortion based on the design layout and the corrected SEM image; and a third determination module 550 determines to terminate the correction of the SEM image if the amount of distortion is smaller than a predetermined threshold.

[0091] Preferably, the third determination module 550 further returns to the step of determining keypoint pairs based on the design layout and the corrected SEM image if the distortion amount is equal to or greater than a predetermined threshold.

[0092] Preferably, the first determination module 520 includes: an establishment unit for establishing a Cartesian coordinate system O-XY with the geometric center as the coordinate origin O when the geometric centers of the design layout and the SEM image are aligned; a first selection unit for selecting, in the XY plane, an image cell in the SEM image that is at least one period shifted with respect to the design layout as a first image cell; a second selection unit for selecting, from the design layout, a second image cell at a position corresponding to the first image cell; and a third selection unit for selecting one coordinate point at the same position of the first image cell and the second image cell as a keypoint pair.

[0093] Preferably, the first selection unit specifically performs the steps of selecting, in a first direction in the XY plane, at least one image cell of the SEM image that is periodically shifted relative to the design layout as a first image cell, and selecting, in a second direction in the XY plane, at least one image cell of the SEM image that is periodically shifted relative to the design layout as a first image cell.

[0094] Preferably, the correction module 530 specifically performs the steps of determining correction parameters, including at least one of a rotation parameter, a scaling parameter, and a translation parameter, based on the keypoint pairs, and processing the SEM image according to the correction parameters to determine a corrected SEM image.

[0095] Preferably, the second determination module 540 includes a first determination unit for determining first first order origin moment coordinates of each first image cell of the corrected SEM image and second first order origin moment coordinates of each second image cell of the design layout, and a processing unit for processing the corresponding first order origin moment coordinates and second first order origin moment coordinates of the corrected SEM image and the design layout to determine a distortion amount.

[0096] Preferably, the processing unit specifically performs the steps of: dividing the corrected SEM image and the design layout in the same manner to obtain corresponding first sub-images and second sub-images; and averaging the first first-order origin moment coordinates of the first image cells included in each of the first sub-images and the second first-order origin moment coordinates of the second image cells included in each of the second sub-images to determine the amount of distortion between each of the first sub-images and the corresponding second sub-images.

[0097] Preferably, the third determination module 550 specifically performs the steps of: determining the difference between two adjacent distortion amounts when multiple distortion amounts are acquired; and determining to terminate the correction of the SEM image when any of the differences is a negative number.

[0098] The image correction device according to the present invention may center a design layout of a sample to be detected with an SEM image captured by a scanning electron microscope, determine keypoint pairs based on the design layout and image cells in the SEM image, correct the SEM image based on the keypoint pairs to obtain a corrected SEM image, determine a distortion amount based on the design layout and the corrected SEM image, and determine to end correction of the SEM image if the distortion amount is smaller than a predetermined threshold. In this way, after centering the design layout of the sample to be detected with the SEM image, determine keypoint pairs based on the design layout and image cells in the SEM image, and correct the SEM image based on the keypoint pairs, so that the image cells in the SEM image of the sample to be detected can be matched as closely as possible with the image cells in the design layout, making the determined keypoint pairs more accurate and reliable, and further making the correction of the SEM image more accurate and reliable, thereby improving the accuracy and reliability of SEM image correction.

[0099] 6, an electronic device 600 according to the present invention includes a processor 601 and a memory 602 storing computer program instructions. When the processor 601 executes the computer program instructions, the above-described image correction method is realized.

[0100] A computer-readable storage medium according to the present invention stores computer program instructions which, when executed by a processor, implement the image correction method described above.

[0101] It will be understood that specific features, operations, and details described herein with respect to the methods of the present invention may equally apply to the apparatus and systems of the present invention, and vice versa, and that each step of the methods of the present invention described above may be performed by a corresponding component or unit of the apparatus or system of the present invention.

[0102] As can be understood, each module / unit of the device of the present invention may be realized in whole or in part by software, hardware, firmware, or a combination thereof. Each module / unit may be embedded in the processor of a computer device in the form of hardware or firmware, or may be independent from the processor and stored in the memory of a computer device in the form of software, so that it can be called by the processor to perform the operation of each module / unit. Each module / unit may be realized as an independent component or module, or two or more modules / units may be realized as a single component or module.

[0103] A computing device according to one embodiment includes a memory and a processor. The memory stores computer instructions executable by the processor, which, when executed by the processor, instruct the processor to perform steps of a method according to an embodiment of the present invention. The computing device may broadly be a server, a terminal, or any other electronic device having necessary computing and / or processing capabilities. In one embodiment, the computing device may include a processor, memory, a network interface, a communication interface, etc., connected via a system bus. The processor of the computing device may provide the necessary computing, processing, and / or control capabilities. The memory of the computing device may include a non-volatile storage medium and an internal memory. The non-volatile storage medium may store an operating system, a computer program, etc. The internal memory may provide an environment for the execution of the operating system and the computer program on the non-volatile storage medium. The network interface and communication interface of the computing device may be used to connect to and communicate with external devices via a network. The computer program, when executed by the processor, performs the steps of the method according to the present invention.

[0104] The present invention may be embodied as a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the steps of the method of the present invention. In one embodiment, the computer program is distributed across multiple network-connected computer devices or processors so as to be stored, accessed, and executed in a distributed manner by one or more computer devices or processors. A single method step / operation, or two or more method steps / operations, may be performed by a single computer device or processor, or two or more computer devices or processors. One or more method steps / operations may be performed by one or more computer devices or processors, and one or more other method steps / operations may be performed by one or more other computer devices or processors. One or more computer devices or processors may perform a single method step / operation, or two or more method steps / operations.

[0105] As will be understood by those skilled in the art, the method steps of the present invention may be accomplished by a computer program instructing a computer device or related hardware, such as a processor, and the computer program may be stored in a non-transitory computer-readable storage medium, which, when executed, performs the steps of the present invention. In some cases, any reference herein to memory, storage, database, or other medium may include non-volatile memory and / or volatile memory. Examples of non-volatile memory include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), flash memory, magnetic tape, flexible disk, magneto-optical data storage device, optical data storage device, hard disk, solid-state disk, etc. Examples of volatile memory include random access memory (RAM), external cache memory, etc.

[0106] The above-mentioned technical features may be combined in any desired manner. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be included in this specification unless such combination is inconsistent.

[0107] Finally, it should be noted that the above embodiments are merely for explaining the technical means of the present invention and are not limiting. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical means described in the above embodiments or make equivalent substitutions for part or all of the technical features thereof, and it should be understood that such modifications or substitutions will not deviate from the scope of the technical means of the embodiments of the present invention.

Claims

1. centering the design layout of the sample to be detected with the SEM image of the scanning electron microscope; determining keypoint pairs based on the design layout and image cells in the SEM image; correcting the SEM image based on the keypoint pairs to obtain a corrected SEM image; determining an amount of distortion based on the design layout and the corrected SEM image; and determining to terminate correction of the SEM image when the distortion amount is smaller than a predetermined threshold.

2. After determining the amount of distortion based on the design layout and the corrected SEM image, 2. The image correction method of claim 1, further comprising the step of returning to and executing the step of determining key point pairs based on the design layout and the corrected SEM image when the amount of distortion is equal to or greater than a predetermined threshold.

3. determining keypoint pairs based on the design layout and image cells in the SEM image, When the geometric centers of the design layout and the SEM image are aligned, establishing an orthogonal coordinate system O-XY with the geometric center as a coordinate origin O; selecting, in an XY plane, at least one image cell in the SEM image that is periodically shifted with respect to the design layout as a first image cell; selecting a second image cell from the design layout at a location corresponding to the first image cell; and selecting one coordinate point at the same location in the first image cell and the second image cell as a keypoint pair.

4. The step of selecting, in the XY plane, at least one image cell in the SEM image that is periodically shifted with respect to the design layout as a first image cell includes: selecting, as a first image cell, at least one image cell in the SEM image that is periodically shifted with respect to the design layout in a first direction in the XY plane; 4. The image correction method according to claim 3, further comprising the step of selecting, as a first image cell, at least one image cell in the SEM image that is periodically shifted with respect to the design layout in a second direction in the XY plane.

5. correcting the SEM image based on the keypoint pairs to obtain a corrected SEM image, determining correction parameters based on the keypoint pairs, the correction parameters including at least one of a rotation parameter, a scaling parameter, and a translation parameter; and processing the SEM image in accordance with the correction parameters to determine a corrected SEM image.

6. determining an amount of distortion based on the design layout and the corrected SEM image, determining a first first order moment of origin coordinate for each first image cell of the corrected SEM image and a second first order moment of origin coordinate for each second image cell of the design layout; and processing corresponding first and second first order origin moment coordinates of the corrected SEM image and the design layout to determine an amount of distortion.

7. processing corresponding first and second first order origin moment coordinates of the corrected SEM image and the design layout to determine distortion amounts; segmenting the corrected SEM image and the design layout in the same manner to obtain corresponding first and second sub-images; 7. The image correction method of claim 6, further comprising: determining an amount of distortion between each of the first sub-images and the corresponding second sub-image by averaging first first-order moment coordinates of the origin of a first image cell included in each of the first sub-images and second first-order moment coordinates of the origin of a second image cell included in each of the second sub-images.

8. The step of determining to terminate the correction of the SEM image includes: When a plurality of distortion amounts are acquired, determining the difference between two adjacent distortion amounts; 2. The image correction method according to claim 1, further comprising the step of: determining to terminate correction of the SEM image if any of the differences is a negative number.

9. an alignment module for aligning the center of the design layout of the sample to be detected with the SEM image of the scanning electron microscope; a first determination module that determines keypoint pairs based on the design layout and image cells in the SEM image; a correction module that corrects the SEM image based on the keypoint pairs to obtain a corrected SEM image; a second determination module that determines an amount of distortion based on the design layout and the corrected SEM image; and a third decision module that decides to end the correction of the SEM image when the distortion amount is smaller than a predetermined threshold.

10. a processor and a memory having computer program instructions stored therein; 9. An electronic device, wherein the processor, when executing the computer program instructions, implements the image correction method according to claim 1.

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