Image correction method and device

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 in particular to an image correction method and apparatus. [Background technology]

[0002] With the development of integrated circuits, electron beam detection technology is also constantly improving. Usually, secondary electron images can be collected using electron beam detection and measurement devices. However, in the process of scanning using electron beam detection and measurement devices, the electron gun is susceptible to factors such as mechanical vibration and surface charge accumulation effect, so there may be some distortion in the obtained scanning electron microscope (SEM) image. Therefore, the obtained SEM image needs to be corrected.

[0003] In the related art, when correcting an SEM image, usually, first, an SEM image of a standard sample is taken, and the distortion amount and magnification difference are calculated based on the SEM image, and then the result is applied to correct the SEM image of the sample to be detected, which depends heavily on the state of the standard sample. Since the correction work of the SEM image is completed on a non-real sample, there may be differences between the material and surface state of the real sample and the standard sample, so the distortion amount of the real sample and the distortion amount of the standard sample may not be completely consistent, resulting in low correction effect and low 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 the prior art, when correcting an SEM image, there may be differences between the material and surface condition of the actual sample and the standard sample, so that the amount of distortion of the actual sample to be detected and the amount of distortion of the standard sample may not completely match, resulting in low correction effect 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 and 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 the 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 the 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 the design layout and image cells in the SEM image includes the steps of: 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; 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 periodically shifted relative to the design layout in the XY plane as the first image cell includes a step of selecting at least one image cell in the SEM image that is periodically shifted relative to the design layout in a first direction in the XY plane as the first image cell, and a step of selecting at least one image cell in the SEM image that is periodically 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 corresponding first order origin moment coordinates and second 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 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 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, respectively, 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 a difference between two adjacent distortion amounts when multiple distortion amounts are acquired; and deciding to terminate the correction of the SEM image when any difference 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 and 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 decides 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 amount of distortion 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 at least one image cell of the SEM image that is periodically shifted with respect to the design layout in the XY plane as a first image cell; a second selection unit for selecting a second image cell from the design layout 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 key point pair.

[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 with respect 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 with respect 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 according to the correction parameters to determine a corrected SEM image.

[0018] Preferably, the second determination module includes a first determination unit for 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 a processing unit for processing corresponding first order origin moment coordinates and second 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 a difference between two adjacent distortion amounts when multiple distortion amounts are acquired; and determining to terminate correction of the SEM image when any difference is a negative number.

[0021] According to a third aspect of the present invention, there is provided an electronic device comprising a processor and a memory having computer program instructions stored therein, The processor, when executing the computer program instructions, implements any of the image correction methods described above.

[0022] A computer-readable storage medium according to a fourth aspect of the present invention is characterized in that computer program instructions are stored therein which, 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 device, which includes the steps of: aligning the center of a design layout of a sample to be detected with an SEM image obtained by a scanning electron microscope; determining a keypoint pair based on the design layout and image cells in the SEM image; correcting the SEM image based on the keypoint pair 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 value. In this way, after aligning the center of a design layout of a sample to be detected with an SEM image, a keypoint pair may be determined based on the image cells in the design layout and the SEM image; and the SEM image may be corrected based on the keypoint pair, and the image cells in the SEM image of the sample to be detected and the image cells in the design layout may be matched as much as possible, so that the determined keypoint pair is more accurate and reliable, and the correction of the SEM image is more accurate and reliable, thereby improving the accuracy and reliability of the SEM image correction. [Brief description 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] 4 is a flowchart of an image correction method according to an embodiment of the present invention. [Diagram 2] 4 is a flowchart of an image correction method according to an embodiment of the present invention. [Diagram 3] 1 is a schematic diagram 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; [Diagram 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 PREFERRED EMBODIMENTS

[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 in this specification 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 one 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 enhancement method according to the embodiment of the present invention may be performed by an image enhancement 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 obtained by 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 also several methods for centering the design layout of the sample to be detected and the image obtained by the scanning electron microscope. For example, the geometric center of the design layout of the sample to be detected and the geometric center of the SEM image may be determined, respectively, and then the two may be aligned. Alternatively, after the geometric center of the design layout and the geometric center of the SEM image are determined, respectively, a first center pattern cell closest to the geometric center of the design layout may be determined, and then a second center pattern cell closest to the geometric center of the SEM image may be determined, and the second center pattern cell may be aligned with the first center pattern cell, but the present invention is not limited thereto.

[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 location of the first keypoint in the SEM image may correspond to the location of the second keypoint in the design layout, but the invention is not limited thereto.

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

[0036] Preferably, when centering the design layout and the SEM image, a wide field of view (FOV) may be moved or adjusted until an image cell in the SEM image is shifted from the design layout by more than one period, and when a position of a first image cell 1 in the SEM image corresponds to a 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 that corresponds to it, 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 sizes, shapes, positions, etc. of the first image cells and second image cells in FIG. 4 are merely illustrative and do not limit the first image cells and second image cells, etc. in the embodiments 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 and the image cells in the design layout can be as consistent as possible. Therefore, in the embodiment of the present invention, the design layout is taken as the basis for SEM image correction, and the SEM image correction process is obtained based on the corresponding design layout, which provides conditions for improving the accuracy of SEM image correction thereafter.

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

[0042] After the keypoint pairs are determined, there are several ways to correct 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 obtaining the corrected SEM image, 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 methods for determining 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 thereto.

[0047] In addition, when processing the first and second first-order origin moment coordinates to determine the distortion amount, multiple methods may be used. 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 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 obtained 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 and the image cells in the design layout can be matched as much as possible, so that the determined keypoint pairs can be more accurate and reliable; further, the SEM image is processed using more accurate and reliable keypoint pairs to effectively avoid inaccuracies in correction caused by differences between the sample to be detected and the standard sample, 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 to end the correction of the current SEM image. If the distortion amount is equal to or greater than the predetermined threshold, it is considered to still need to continue correcting the current SEM image, and at this time, it may be possible to 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, and then re-determine the distortion amount 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 possible to return to the above process of determining keypoint pairs based on the design layout and the re-corrected SEM image until the distortion amount is less than the predetermined threshold.

[0053] In an embodiment of the present invention, after centering between the design layout and the SEM image of the sample to be detected by the 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, and 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, it may be determined to end the correction of the SEM image. In this way, after centering between the design layout and the SEM image of the sample to be detected, keypoint pairs may be determined based on the image cells in the design layout and 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 and the image cells in the design layout can be matched as much as possible, so that the determined keypoint pairs can be made more accurate and reliable, and the correction of the SEM image can be made more accurate and reliable, thereby improving the accuracy and reliability of the 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 SEM image is aligned with the design layout of the sample to be detected.

[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 a design layout and an 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, at least one image cell of the SEM image that is shifted in period 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 with the coordinate origin O as a starting point, 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 thereto.

[0061] Preferably, at least one image cell of the SEM image that is periodic 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 periodic 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 perpendicular to each other, for example, the X-axis direction and the Y-axis direction, or any two mutually perpendicular directions in the XY plane, but the present invention is not limited thereto.

[0063] Step 204 involves selecting 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 image cells in the SEM image have a one-to-one correspondence, 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, when the determined first image cell and second image cell are as shown in the dashed block diagram in FIG. 4, the upper right vertex may be selected as the 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 a scaling parameter, a scaling and a translation parameter, or a rotation, a scaling, and a 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 ways to determine the correction parameters to process the SEM image, for example, if "+" indicates clockwise rotation and "-" indicates counterclockwise rotation, then 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 matrix form. For example, if a total of three sets of keypoint pairs are currently determined, the 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 with the corresponding image matrix of the SEM image to obtain a corrected SEM image.

[0073] It should be noted that the above examples are merely illustrative and do 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 may 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 the correction of the SEM image is to be terminated.

[0083] As can be understood, in the process of correcting an SEM image, typically multiple corrections may be required, so multiple distortion amounts may be obtained, and these multiple distortion amounts may vary accordingly. The correction of the SEM image may be terminated when the difference between the distortion amounts obtained in any two adjacent times is a negative number.

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

[0085] Preferably, when there are multiple first sub-images and second sub-images, when determining the difference between two adjacent distortion amounts, the difference between two adjacent distortion amounts of each of the first sub-images and second sub-images 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 thereto.

[0086] Preferably, after deciding whether or not 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 consideration may be given only to whether the difference between two adjacent amounts of distortion is a negative number, or consideration may be given 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 satisfied, it may be decided 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 the 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, and then at least one image cell of the SEM image that is periodically shifted from the design layout in the XY plane 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, and then correction parameters are determined based on the keypoint pair, and the SEM image is processed according to the correction parameters to determine a corrected SEM image, and then the corrected SEM image and the design layout are divided in the same manner to obtain corresponding first sub-images and second sub-images, and 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, and when the distortion amount is smaller than a predetermined threshold, it may be determined to end the correction of the SEM image. In this way, after aligning 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. Since 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, the determined keypoint pairs can be made more accurate and reliable, and the correction of the SEM image can be made more accurate and reliable, thereby improving the accuracy and reliability of the SEM image correction.

[0089] As shown in FIG. 5, the image correction apparatus 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 an 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 determining 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 a coordinate origin O when the geometric centers of the design layout and the SEM image are aligned; a first selection unit for selecting at least one image cell in the SEM image that is periodically shifted from the design layout in the XY plane as a first image cell; a second selection unit for selecting a second image cell from the design layout 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 key point pair.

[0093] Preferably, the first selection unit specifically performs the steps of selecting at least one image cell of the SEM image that is periodically shifted with respect 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 with respect to the design layout in a second direction in the XY plane 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 pair, 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 a first first-order origin moment coordinate of each first image cell of the corrected SEM image and a second first-order origin moment coordinate of each second image cell of the design layout, and a processing unit for processing the corresponding first 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.

[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 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.

[0097] Preferably, the third determination module 550 specifically executes 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.

[0098] The image correction device according to the present invention may perform centering between a design layout of a sample to be detected and an SEM image obtained by a scanning electron microscope, determine a keypoint pair based on the design layout and image cells in the SEM image, correct the SEM image based on the keypoint pair to obtain a corrected SEM image, and further determine a distortion amount based on the design layout and the corrected SEM image, and determine to end the correction of the SEM image when the distortion amount is smaller than a predetermined threshold value. In this way, after performing centering between the design layout of a sample to be detected and an SEM image, a keypoint pair may be determined based on the image cells in the design layout and the SEM image, and the SEM image may be corrected based on the keypoint pair, and 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, so that the determined keypoint pair can be made more accurate and reliable, and the correction of the SEM image can be made more accurate and reliable, thereby improving the accuracy and reliability of the SEM image correction.

[0099] 6, an electronic device 600 according to the present invention includes a processor 601 and a memory 602 in which computer program instructions are stored. When the processor 601 executes the computer program instructions, the electronic device 600 realizes the image correction method described above.

[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] As will be understood, specific features, operations and details described herein with respect to the methods of the present invention may equally be applied to the apparatus and system of the present invention, and vice versa, and each step of the methods of the present invention described above may be performed by a corresponding part 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 of the processor and stored in the memory of a computer device in the form of software, so as to be called by the processor to execute 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 an embodiment includes a memory and a processor, and the memory stores computer instructions executable by the processor, which, when executed by the processor, instruct the processor to perform each step of the method of the 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, a 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 in the non-volatile storage medium. The network interface and the communication interface of the computing device may be used to connect to and communicate with an external device via a network. The computer program, when executed by the processor, performs the steps of the method of the present invention.

[0104] The present invention may be implemented 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 embodiment of the present invention. In one embodiment, the computer program is distributed across multiple networked computer devices or processors such that it is 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 can be understood by those skilled in the art, the method steps of the present invention may be completed 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, and when executed, the steps of the present invention are performed. In some cases, any reference to memory, storage, database, or other medium in this specification 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, floppy 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] Each of the above-mentioned technical features may be combined in any combination. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be included in the present 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 may still modify the technical means described in the above embodiments or make equivalent substitutions to some or all of the technical features thereof, and such modifications or substitutions will not cause the essence of the corresponding technical means to depart 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 end correction of the SEM image when the amount of distortion is smaller than a predetermined threshold.

2. After the step of 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 if 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 includes: When the geometric centers of the design layout and the SEM image are aligned, a Cartesian coordinate system O-XY is established with the geometric center as a coordinate origin O; selecting at least one image cell in the SEM image that is out of period with respect to the design layout as a first image cell in an XY plane; 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 an XY plane, at least one image cell in the SEM image that is out of period with respect to the design layout as a first image cell includes: selecting at least one image cell in the SEM image that is out of period with respect to the design layout in a first direction in the XY plane as a first image cell; 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 out of period with respect to the design layout in a second direction in the XY plane.

5. correcting the SEM image based on the key point 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 includes: 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 an amount of distortion; segmenting the corrected SEM image and the design layout in a same manner to obtain corresponding first and second sub-images; 7. The image correction method of claim 6, further comprising: averaging first first order moment coordinates of origin of first image cells included in each of the first sub-images and second first order moment coordinates of origin of second image cells included in each of the second sub-images to determine an amount of distortion between each of the first sub-images and the corresponding second sub-image.

8. The step of determining to end the correction of the SEM image includes: determining a difference between two adjacent distortion amounts when a plurality of distortion amounts are acquired; 2. The method of 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 centering a design layout of a sample to be detected and a SEM image of the sample; a first determination module that determines keypoint pairs based on the design layout and image cells in the SEM image; a correction module for correcting 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; The electronic device, wherein the processor, when executing the computer program instructions, implements the image correction method according to any one of claims 1 to 8.

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