Image correction method and apparatus

Abstract

The application provides an image correction method and device, the method comprising: centering a design layout of a sample to be measured and a scanning electron microscope (SEM) image; determining a key point pair based on the design layout and an image unit in the SEM image; correcting the SEM image based on the key point pair to obtain a corrected SEM image; determining a distortion variable based on the design layout and the corrected SEM image; and determining that the SEM image correction is completed when the distortion variable is less than a preset threshold. Thus, the key point pair can be determined based on the design layout and the image unit in the SEM image, and the SEM image is corrected based on the key point pair. Since the image unit in the SEM image of the sample to be measured and the image unit in the design layout can be kept consistent as much as possible, the correction of the SEM image is more accurate and reliable, thereby improving the accuracy and reliability of the SEM image correction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, and in particular, to an image correction method and device. BACKGROUND

[0002] With the development of integrated circuits, electron beam detection technology is also constantly progressing. Generally, a secondary electron image can be collected by using an electron beam detection and measurement device. However, in the scanning process by using the electron beam detection and measurement device, the electron gun is easily affected by mechanical vibration and surface charge accumulation effect, and thus part of the scanning electron microscope (SEM) image obtained can be distorted. Therefore, it is necessary to correct the SEM image obtained.

[0003] In the related art, when the SEM image is corrected, the SEM image of a standard sample is usually first shot, the distortion variable size and the magnification difference are calculated according to the SEM image, and then the results are applied to the SEM image correction of the sample to be measured. In this way, the state of the standard sample is largely relied on. Since the SEM image correction is completed on a non-actual detection sample, there can be differences between the material and surface state of the actual sample and the standard sample, so that the distortion variable of the actual sample to be measured can not be completely consistent with the distortion variable of the standard sample, the correction effect is poor, and the accuracy is low. Therefore, how to improve the accuracy of the SEM image correction is very important. SUMMARY

[0004] In the prior art, since there can be differences between the material and surface state of the actual sample and the standard sample, the distortion variable of the actual sample to be measured can not be completely consistent with the distortion variable of the standard sample, the correction effect is poor, and the accuracy is low.

[0005] According to a first aspect of the present application, an image correction method is provided, which comprises: centering a design layout of a sample to be measured with a scanning electron microscope (SEM) image; determining a key point pair based on an image unit in the design layout and the SEM image; correcting the SEM image based on the key point pair to obtain a corrected SEM image; determining a distortion variable based on the design layout and the corrected SEM image; and determining that the SEM image correction is completed in a case where the distortion variable is less than a preset threshold.

[0006] Optionally, after the step of determining the distortion variable based on the design layout and the corrected SEM image, the method further comprises: in a case where the distortion variable is greater than or equal to the preset threshold, returning to the step of determining the key point pair based on the design layout and the corrected SEM image.

[0007] Optionally, the determining the key point pair based on the design layout and the image unit in the SEM image comprises: in the case of aligning the geometric centers of the design layout and the SEM image, establishing a rectangular coordinate system O-XY with the geometric center as the coordinate origin O; selecting an image unit in the SEM image which is offset by at least one period relative to the design layout as a first image unit in the XY plane; selecting a second image unit on the design layout corresponding to the position of the first image unit; and selecting one coordinate point at the same position in the first image unit and the second image unit as a key point pair.

[0008] Optionally, the selecting the image unit in the SEM image which is offset by at least one period relative to the design layout as a first image unit in the XY plane comprises: selecting the image unit in the SEM image which is offset by at least one period relative to the design layout as a first image unit in a first direction in the XY plane; and selecting the image unit in the SEM image which is offset by at least one period relative to the design layout as a first image unit in a second direction in the XY plane.

[0009] Optionally, the correcting the SEM image based on the key point pair to obtain a corrected SEM image comprises: determining a correction parameter based on the key point pair, wherein the correction parameter comprises at least one of a rotation parameter, a scaling parameter, and a translation parameter; and processing the SEM image according to the correction parameter to determine the corrected SEM image.

[0010] Optionally, the determining the distortion variable based on the design layout and the corrected SEM image comprises: determining a first first-order origin moment coordinate of each first image unit in the corrected SEM image and a second first-order origin moment coordinate of each second image unit in the design layout; and processing the corresponding first first-order origin moment coordinate and the second first-order origin moment coordinate in the corrected SEM image and the design layout to determine the distortion variable.

[0011] Optionally, the processing the corresponding first first-order origin moment coordinate and the second first-order origin moment coordinate in the corrected SEM image and the design layout to determine the distortion variable comprises: dividing the corrected SEM image and the design layout according to the same manner to obtain corresponding first sub-images and second sub-images; and performing mean processing on the first first-order origin moment coordinate of the first image unit included in each first sub-image and the second first-order origin moment coordinate of the second image unit included in each second sub-image, respectively, to determine the distortion variable between each first sub-image and the corresponding second sub-image.

[0012] Optionally, the determining that the SEM image correction is completed comprises: in a case where a plurality of distortion values are obtained, determining a difference between two adjacent distortion values; and in a case where any difference is negative, determining that the SEM image correction is completed.

[0013] According to a second aspect of the present application, an image correction device is provided, comprising: an alignment module configured to center align a design layout of a sample to be measured and a scanning electron microscope (SEM) image; a first determination module configured to determine a key point pair based on the design layout and an image unit in the SEM image; a correction module configured to correct the SEM image based on the key point pair to obtain a corrected SEM image; a second determination module configured to determine a distortion value based on the design layout and the corrected SEM image; and a third determination module configured to determine that the SEM image correction is completed in a case where the distortion value is less than a preset threshold.

[0014] Optionally, the third determination module is further configured to return to perform the step of determining the key point pair based on the design layout and the corrected SEM image in a case where the distortion value is greater than or equal to the preset threshold.

[0015] Optionally, the first determination module comprises: an establishing unit configured to establish a rectangular coordinate system O-XY with a geometric center of the design layout and the SEM image as a coordinate origin O in a case where the geometric center is center aligned; a first selecting unit configured to select an image unit in the SEM image that is offset by at least one period relative to the design layout as a first image unit in an XY plane; a second selecting unit configured to select a second image unit on the design layout corresponding to a position of the first image unit; and a third selecting unit configured to select one coordinate point at the same position in the first image unit and the second image unit as the key point pair.

[0016] Optionally, the first selecting unit is specifically configured to: select an image unit in the SEM image that is offset by at least one period relative to the design layout as the first image unit in a first direction in the XY plane; and select an image unit in the SEM image that is offset by at least one period relative to the design layout as the first image unit in a second direction in the XY plane.

[0017] Optionally, the correction module is specifically configured to: determine a correction parameter based on the key point pair, wherein the correction parameter comprises at least one of a rotation parameter, a scaling parameter and a translation parameter; and process the SEM image according to the correction parameter to determine the corrected SEM image.

[0018] Optionally, the second determining module comprises: a first determining unit configured to determine first first-order origin moment coordinates of each first image unit in the corrected SEM image and second first-order origin moment coordinates of each second image unit in the design layout; and a processing unit configured to process the corresponding first first-order origin moment coordinates and second first-order origin moment coordinates in the corrected SEM image and the design layout to determine the distortion variable.

[0019] Optionally, the processing unit is specifically configured to: segment the corrected SEM image and the design layout in the same manner to obtain corresponding first sub-images and second sub-images; and perform mean processing on the first first-order origin moment coordinates of the first image units contained in each first sub-image and the second first-order origin moment coordinates of the second image units contained in each second sub-image, respectively, to determine the distortion variable between each first sub-image and the corresponding second sub-image.

[0020] Optionally, the third determining module is specifically configured to: in the case where a plurality of distortion variables are obtained, determine the difference between two adjacent distortion variables; and in the case where any difference is negative, determine that the SEM image correction is completed.

[0021] According to a third aspect of the present application, an electronic device is provided, which comprises a processor and a memory storing computer program instructions;

[0022] The processor implements any of the above image correction methods when executing the computer program instructions.

[0023] According to a fourth aspect of the present application, a computer readable storage medium is provided, which stores computer program instructions, and the computer program instructions are executed by a processor to implement any of the above image correction methods.

[0024] In summary, the present application provides an image correction method and device, the method comprising: the design layout of the sample to be measured can be first aligned with the scanning electron microscope (SEM) image, then based on the image unit in the design layout and the SEM image, the key point pair can be determined, then based on the key point pair, the SEM image can be corrected to obtain the corrected SEM image, and then based on the design layout and the corrected SEM image, the distortion variable is determined, and in the case that the distortion variable is less than the preset threshold, it is determined that the SEM image correction is completed. Therefore, the design layout of the sample to be measured can be first aligned with the SEM image, then based on the image unit in the design layout and the SEM image, the key point pair can be determined, and then based on the key point pair, the SEM image can be corrected. Since the image unit in the SEM image of the sample to be measured and the image unit in the design layout can be kept consistent as much as possible, the determined key point pair can be more accurate and reliable, and then the correction of the SEM image can be more accurate and reliable, thereby improving the accuracy and reliability of the SEM image correction. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0026] Figure 1 A flowchart of an image correction method provided for an embodiment of the present application;

[0027] Figure 2 A flowchart of an image correction method provided for an embodiment of the present application;

[0028] Figure 3 A schematic diagram of a design layout and a SEM image provided for an embodiment of the present application;

[0029] Figure 4 A schematic diagram of an image unit provided for an embodiment of the present application;

[0030] Figure 5 A structural diagram of an image correction device provided for an embodiment of the present application;

[0031] Figure 6 A structural diagram of an electronic device provided for an embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to make the above and other features and advantages of the present application more comprehensible, the present application will be further described below with reference to the drawings. It should be understood that the specific embodiments given herein are by way of example only and are not meant to be limiting.

[0033] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one of ordinary skill in the art that the specific details need not be employed to practice the present application. In other instances, well-known steps or operations have not been described in detail in order to not unnecessarily obscure the present application.

[0034] The image correction method provided by the embodiments of the present application can be executed by the image correction device provided by the embodiments of the present application, which can be configured in an electronic device.

[0035] Reference Figure 1 The present application provides an image correction method, which comprises:

[0036] In step 101, the design layout of the sample to be measured is aligned with the scanning electron microscope image.

[0037] The scanning electron microscope (SEM) can be used to scan the actual sample to be measured, such as a semiconductor silicon wafer, to generate a corresponding SEM image.

[0038] In addition, there are various ways to align the design layout of the sample to be measured with the scanning electron microscope image. For example, the geometric centers of the design layout of the sample to be measured and the SEM image can be determined respectively and then aligned. Alternatively, the geometric centers of the design layout and the SEM image can be determined respectively, and then the first center pattern unit closest to the geometric center in the design layout is determined, and the second center pattern unit closest to the geometric center in the SEM image is determined, and the second center pattern unit is aligned with the first center pattern unit, and the like, which are not limited by the present application.

[0039] In step 102, based on the image units in the design layout and the SEM image, a key point pair is determined.

[0040] The key point pair can include two key points, such as a first key point located in the SEM image and a second key point located in the design layout, the position of the first key point in the SEM image corresponding to the position of the second key point in the design layout, and the like, which are not limited by the present application.

[0041] In addition, the key point pair can be one pair or multiple pairs, and the like, which are not limited by the present application.

[0042] Optionally, when the design layout and SEM image are center-aligned, by moving or adjusting a larger field of view (FOV), until the image unit in the SEM image is offset from the design layout by more than one cycle, if the first image unit 1 in the SEM image corresponds in position to the second image unit 1 in the design layout, then a keypoint pair can be determined in the first image unit 1 and the second image unit 1. For example, the geometric center of the first image unit 1 and the second image unit 1 can be determined as a keypoint pair, or the upper right vertex of the first image unit 1 and the second image unit 1 can be determined as a keypoint pair, and so on.

[0043] In addition, a period can be understood as the period during the observation of a moving FOV, when any first image unit in the SEM image begins to overlap with any second image unit in the design layout that is closest to it, except for the second image unit corresponding to itself.

[0044] For example, in such Figure 4 In the image units shown, the first image unit A corresponds to the second image unit A′. If, when observing in the horizontal direction by moving the FOV, the first image unit A and the second image unit C begin to overlap, then it can be considered that the image unit in the current SEM image is about to be offset from the design layout by more than one cycle; or, in the vertical direction, when observing by moving the FOV, if the first image unit A and the second image unit B begin to overlap, then it can be considered that the image unit in the current SEM image is about to be offset from the design layout by more than one cycle, and so on. This invention does not limit this.

[0045] It should be noted that, Figure 4 The size, shape, and position of the first and second image units in the embodiments of the present invention are merely illustrative and should not be construed as limiting the first and second image units in the embodiments of the present invention.

[0046] It is understood that the actual test sample in this invention is obtained based on the design layout. Due to the strict photomask and photolithography manufacturing process, the image units in the SEM image of the test sample can be made as consistent as possible with the image units in the design layout. Therefore, in this embodiment of the invention, the design layout is used as a reference for SEM image correction. Since the SEM image correction process is based on the corresponding design layout, it provides conditions for improving the accuracy of SEM image correction in the future.

[0047] Step 103: Based on the key point pairs, the SEM image is corrected to obtain the corrected SEM image.

[0048] Wherein, after the key point pairs are determined, there are various methods for correcting the SEM image based on the key point pairs. For example, each group of key point pairs can be processed to determine the correction parameters corresponding to each group of key point pairs, and then the correction parameters are used to correct the SEM image to determine the corrected SEM image, etc. The present application does not limit this.

[0049] Step 104, based on the design layout and the corrected SEM image, the distortion variable is determined.

[0050] Wherein, after the corrected SEM image is obtained, the distortion variable can be further determined based on the first image unit in the corrected SEM image and the second image unit in the design layout.

[0051] Optionally, the first first-order origin moment coordinates of each first image unit in the corrected SEM image and the second first-order origin moment coordinates of each second image unit in the design layout can be determined first, and then the corresponding first first-order origin moment coordinates and second first-order origin moment coordinates in the corrected SEM image and the design layout can be processed to determine the distortion variable.

[0052] Wherein, there are various ways to determine the first first-order origin moment coordinates and the second first-order origin moment coordinates, such as determining by first-order origin moment, or using each coordinate point in the image unit, etc. The present application does not limit this.

[0053] In addition, when the first first-order origin moment coordinates and the second first-order origin moment coordinates are processed to determine the distortion variable, there can be various methods. For example, the first first-order origin moment coordinates and the second first-order origin moment coordinates can be substituted into the Euclidean distance formula, and the result obtained is determined as the distortion variable; or Manhattan distance formula, cosine similarity distance formula, Chebyshev distance formula, etc. The present application does not limit this.

[0054] It can be understood that, in the embodiment of the present application, since the actual sample to be measured is obtained based on the design layout, when the design layout is used to correct the SEM image, the image units in the SEM image of the sample to be measured and the image units in the design layout can be kept consistent as much as possible, so that the determined key point pairs are more accurate and reliable, and then since the more accurate and reliable key point pairs are used to process the SEM image, the inaccuracy caused by the difference between the sample to be measured and the standard sample is effectively avoided, so that the correction of the SEM image is more accurate and reliable, and the accuracy and reliability of the SEM image correction are improved.

[0055] Step 105, in the case where the distortion variable is less than the preset threshold, it is determined that the SEM image correction is ended.

[0056] The preset threshold value can be a value set in advance, or can be adjusted according to actual needs, and the present application does not limit this.

[0057] Optionally, in the case that the distortion amount is greater than or equal to the preset threshold value, based on the design layout and the corrected SEM image, the step of determining the key point pair is returned to be executed.

[0058] It can be understood that, in the process of correcting the SEM image, if the distortion amount is less than the preset threshold value, it can be considered that the correction of the SEM image is ended. If the distortion amount is greater than or equal to the preset threshold value, it can be considered that the SEM image still needs to be continuously corrected. At this time, based on the design layout and the corrected SEM image, the step of determining the key point pair is returned to be executed. After the key point pair corresponding to the design layout and the corrected SEM image is determined, the corrected SEM image can be corrected based on the updated key point pair to obtain a re-corrected SEM image. Then, based on the design layout and the re-corrected SEM image, the distortion amount is determined again. If the distortion amount at this time is less than the preset threshold value, it can be determined that the correction of the SEM image is ended. If the distortion amount at this time is still greater than or equal to the preset threshold value, the process of determining the key point pair is returned to be repeatedly executed based on the design layout and the re-corrected SEM image, until the distortion amount is less than the preset threshold value.

[0059] In the embodiment of the present application, the design layout of the sample to be measured and the SEM image can be first centered. Then, based on the design layout and the image unit in the SEM image, the key point pair can be determined. Then, based on the key point pair, the SEM image can be corrected to obtain a corrected SEM image. Then, based on the design layout and the corrected SEM image, the distortion amount is determined. In the case that the distortion amount is less than the preset threshold value, it is determined that the correction of the SEM image is ended. In this way, the design layout of the sample to be measured and the SEM image can be first centered. Then, based on the design layout and the image unit in the SEM image, the key point pair can be determined. Then, based on the key point pair, the SEM image can be corrected. Since the image unit in the SEM image of the sample to be measured and the image unit in the design layout can be kept consistent as much as possible, the determined key point pair can be more accurate and reliable, and the correction of the SEM image can be more accurate and reliable, thereby improving the accuracy and reliability of the correction of the SEM image.

[0060] Figure 2 A flowchart of an image correction method provided by the embodiment of the present application is shown.

[0061] As shown in Figure 2 , the image correction method can include the following steps:

[0062] Step 201, centering the design layout of the sample to be measured and the SEM image.

[0063] Step 202, under the condition that the design layout and the SEM image are centered, establishing a rectangular coordinate system O-XY with the geometric center as the coordinate origin O.

[0064] For example, the geometric center of the design layout and the SEM image can be determined first, and then the rectangular coordinate system O-XY can be established with the geometric center as the coordinate origin O. For example, the design layout can be as shown in part (a) of Figure 3 , the SEM image can be as shown in part (b) of Figure 3 , and the image after centering the two with the geometric center can be as shown in part (c) of Figure 3 , and the like, which are not limited by the present application.

[0065] Step 203, selecting an image unit in the SEM image that is offset by at least one period relative to the design layout as a first image unit in the XY plane.

[0066] Wherein, the image unit in the SEM image can be determined as the first image unit when the SEM image is about to exceed one period relative to the design layout by moving the larger field of view FOV to the edge from the coordinate origin O. The number of the first image unit can be one, or can be multiple, and the like, which are not limited by the present application.

[0067] Optionally, an image unit in the SEM image that is offset by at least one period relative to the design layout can be selected as a first image unit in a first direction in the XY plane, or an image unit in the SEM image that is offset by at least one period relative to the design layout can be selected as a first image unit in a second direction in the XY plane.

[0068] Wherein, the first direction and the second direction can be two mutually orthogonal directions, such as the X-axis direction and the Y-axis direction, or any two mutually orthogonal directions in the XY plane, and the like, which are not limited by the present application.

[0069] Step 204, selecting a second image unit on the design layout corresponding to the first image unit.

[0070] Wherein, under the condition that the design layout and the SEM image are centered, the image units in the design layout and the image units in the SEM image are one-to-one corresponding in position, so that after the first image unit in the SEM image is determined, the image unit corresponding to the first image unit, i.e. the second image unit, can be selected on the design layout.

[0071] Step 205, one coordinate point in the same position in the first image unit and the second image unit is selected as a key point pair.

[0072] For example, the coordinate point in the center position in the first image unit and the second image unit can be determined as a group of key point pairs; or the coordinate point at the top left vertex in the first image unit and the second image unit can be determined as a group of key point pairs; or the coordinate point at the top right vertex in the first image unit and the second image unit can be determined as a group of key point pairs, and the like, such as in the case shown in the dashed box in FIG. 1C. Figure 4

[0073] It should be noted that the above examples are only illustrative and cannot be regarded as a limitation on the manner of determining the key point pairs in the embodiments of the present application.

[0074] Step 206, based on the key point pairs, determining a correction parameter, wherein the correction parameter includes at least one of the following: a rotation parameter, a scaling parameter, and a translation parameter.

[0075] The key point pairs can be processed after being determined to determine the rotation parameter, the scaling parameter, and the translation parameter. Only one of the rotation parameter, the scaling parameter, and the translation parameter can be determined, or multiple parameters can be determined, such as the rotation parameter and the scaling parameter, the scaling parameter and the translation parameter, the rotation parameter, the scaling parameter, and the translation parameter, and the like, which are not limited by the present application.

[0076] Step 207, processing the SEM image according to the correction parameter to determine a corrected SEM image.

[0077] The SEM image can be processed in various ways when the correction parameter is determined. For example, in the case where "+" represents clockwise rotation and "-" represents counterclockwise rotation, if the determined rotation parameter is +5°, the SEM image can be directly rotated 5° clockwise, and the like, which are not limited by the present application.

[0078] Alternatively, the SEM image can be corrected by a matrix. For example, if three groups of key point pairs are determined, the corresponding correction parameters can be determined by processing the key point pairs, such as two rotation parameters, two scaling parameters, and two translation parameters. The parameter matrix can be constructed by using the above correction parameters, and then the parameter matrix and the image matrix corresponding to the SEM image can be multiplied to obtain the corrected SEM image.

[0079] ​It should be noted that the above examples are merely illustrative and should not be construed as limiting the methods for processing SEM images in the embodiments of the present invention.

[0080] Step 208: Divide the corrected SEM image and the design layout in the same way to obtain the corresponding first sub-image and second sub-image.

[0081] There are several ways to segment the corrected SEM image and design layout. For example, the corrected SEM image and design layout can be segmented into a first sub-image and a second sub-image along the X and Y axes, centered on the origin. Alternatively, the corrected SEM image and design layout can be segmented into a first sub-image and a second sub-image according to a period, such as one period or multiple periods, etc. This invention does not limit the method.

[0082] Furthermore, the number of the first sub-image and the second sub-image can be one or more, etc., and the present invention does not limit this.

[0083] Step 209: The first first-order origin moment coordinates of the first image unit contained in each first sub-image and the second first-order origin moment coordinates of the second image unit contained in each second sub-image are respectively averaged to determine the distortion between each first sub-image and the corresponding second sub-image.

[0084] For example, in the first sub-image and the second sub-image, such as Figure 4 In the case shown, the first first-order origin moment coordinates of each first image unit and the second first-order origin moment coordinates of each second image unit can be determined first. Then, the first first-order origin moment coordinates in the first sub-image (1) can be summed and then averaged. The average is used as the first total first-order origin moment coordinates corresponding to the first sub-image (1). The second first-order origin moment coordinates in the second sub-image (1) can be averaged to determine the second total first-order origin moment coordinates corresponding to the second sub-image (1). Then, based on the first total first-order origin moment coordinates and the second total first-order origin moment coordinates, the distortion between the first sub-image (1) and the second sub-image (1) can be determined. The distortion between each first sub-image and the corresponding second sub-image can be determined sequentially by referring to the above method.

[0085] It should be noted that the above examples are merely illustrative and should not be construed as limiting the methods for determining the distortion variables of the first and second sub-images in the embodiments of the present invention.

[0086] Optionally, after determining the distortion variables between each first sub-image and the corresponding second sub-image, the distortion variables can be output in the form of a heatmap, or in the form of a data table, etc. The present invention does not limit this.

[0087] In step 210, if the distortion value is less than the preset threshold, it is determined that the SEM image correction is completed.

[0088] Optionally, if the difference between the distortion values obtained in two adjacent times is negative, it is determined that the SEM image correction is completed.

[0089] It can be understood that, in the process of correcting the SEM image, multiple corrections are usually needed, and thus multiple distortion values can be obtained, which can change. If the difference between the distortion values obtained in two adjacent times is negative, it is determined that the SEM image correction is completed.

[0090] For example, if the distortion value obtained after the first correction of the SEM image is 0.3, the distortion value obtained after the second correction is 0.35, the distortion value obtained after the third correction is 0.4, and the distortion value obtained after the fourth correction is 0.25, the difference between the distortion value obtained after the fourth correction and the distortion value obtained after the third correction is negative, and thus it is determined that the SEM image correction is completed, and the like. The present application is not limited in this regard.

[0091] Optionally, if there are multiple first sub-images and second sub-images, when determining the difference between the distortion values obtained in two adjacent times, the difference between the distortion values of each first sub-image and second sub-image obtained in two adjacent times can be determined in sequence, and if both satisfy the condition, it is determined that the SEM image correction is completed, and the like. The present application is not limited in this regard.

[0092] Optionally, after determining whether the SEM image correction is completed, only whether the distortion value is less than the preset threshold can be considered, or only whether the difference between the distortion values obtained in two adjacent times is negative can be considered, or both whether the distortion value is less than the preset threshold and whether the difference between the distortion values obtained in two adjacent times is negative can be considered, and if both satisfy the condition, it is determined that the SEM image correction is completed, and the like. The present application is not limited in this regard.

[0093] Optionally, if the distortion value is greater than or equal to the preset threshold, based on the design layout and the corrected SEM image, the step of determining the key point pair is returned to be executed.

[0094] In this embodiment of the invention, when the design layout of the sample to be tested is aligned with the geometric center of the SEM image, a rectangular coordinate system O-XY is established with the geometric center as the origin O. Then, in the XY plane, an image unit in the SEM image that is offset from the design layout by at least one cycle is selected as the first image unit. A second image unit corresponding to the first image unit is selected on the design layout. Then, one of the coordinate points at the same position in the first and second image units is selected as a key point pair. Then, based on the key point pair, correction parameters can be determined, and the SEM image is processed according to the correction parameters to determine the corrected SEM image. Then, the corrected SEM image and the design layout are segmented in the same way to obtain corresponding first sub-images and second sub-images. The first first-order origin moment coordinates of the first image unit contained in each first sub-image and the second first-order origin moment coordinates of the second image unit contained in each second sub-image are respectively averaged to determine the distortion between each first sub-image and the corresponding second sub-image. When the distortion is less than a preset threshold, the SEM image correction is determined to be complete. Therefore, the design layout of the sample to be tested can be aligned with the SEM image first. Then, based on the first and second image units in the SEM image, key point pairs can be determined, and the SEM image can be corrected. Since the image units in the SEM image of the sample to be tested can be kept as consistent as possible with the image units in the design layout, the determined key point pairs can be more accurate and reliable, which in turn makes the correction of the SEM image more accurate and reliable, thereby improving the accuracy and reliability of SEM image correction.

[0095] According to the present invention, an image correction device is provided, such as... Figure 5 As shown, the device 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.

[0096] Alignment module 510 is used to center-align the design layout of the sample to be tested with the scanning electron microscope (SEM) image; first determination module 520 is used to determine key point pairs based on the design layout and image units in the SEM image; correction module 530 is used to correct the SEM image based on the key point pairs to obtain a corrected SEM image; second determination module 540 is used to determine the distortion variable based on the design layout and the corrected SEM image; third determination module 550 is used to determine that the SEM image correction is complete when the distortion variable is less than a preset threshold.

[0097] Optionally, the third determining module 550 is further configured to, based on the design layout and the corrected SEM image, return to the step of determining key point pairs when the distortion is greater than or equal to a preset threshold.

[0098] Optionally, the first determining module 520 comprises: an establishing unit configured to establish a rectangular coordinate system O-XY with a geometric center of the design layout and the SEM image as a coordinate origin O, on the condition that the design layout and the SEM image are aligned at the geometric center; a first selecting unit configured to select, in the XY plane, an image unit in the SEM image that is offset by at least one period relative to the design layout as a first image unit; a second selecting unit configured to select, on the design layout, a second image unit at a position corresponding to the first image unit; and a third selecting unit configured to select one of coordinate points at the same position in the first image unit and the second image unit as a key point pair.

[0099] Optionally, the first selecting unit is specifically configured to: select, in a first direction in the XY plane, an image unit in the SEM image that is offset by at least one period relative to the design layout as a first image unit; and select, in a second direction in the XY plane, an image unit in the SEM image that is offset by at least one period relative to the design layout as a first image unit.

[0100] Optionally, the correcting module 530 is specifically configured to: determine a correction parameter based on the key point pair, wherein the correction parameter comprises at least one of a rotation parameter, a scaling parameter, and a translation parameter; and process the SEM image according to the correction parameter to determine a corrected SEM image.

[0101] Optionally, the second determining module 540 comprises: a first determining unit configured to determine a first first-order origin moment coordinate of each first image unit in the corrected SEM image and a second first-order origin moment coordinate of each second image unit in the design layout; and a processing unit configured to process the corresponding first first-order origin moment coordinate and the second first-order origin moment coordinate in the corrected SEM image and the design layout to determine a distortion variable.

[0102] Optionally, the processing unit is specifically configured to: divide the corrected SEM image and the design layout in the same manner to obtain corresponding first sub-images and second sub-images; and perform mean processing on the first first-order origin moment coordinate of each first image unit included in each first sub-image and the second first-order origin moment coordinate of each second image unit included in each second sub-image, respectively, to determine a distortion variable between each first sub-image and a corresponding second sub-image.

[0103] Optionally, the third determining module 550 is specifically configured to: in the case where a plurality of distortion variables are obtained, determine a difference value between two adjacent distortion variables; and in the case where any difference value is negative, determine that the SEM image correction is completed.

[0104] The image correction device provided by the present application can first align the design layout of the sample to be measured and the scanning electron microscope (SEM) image in the center, and then determine the key point pairs based on the image units in the design layout and the SEM image. Then, the SEM image can be corrected based on the key point pairs, and the corrected SEM image is obtained. Then, the distortion variable is determined based on the design layout and the corrected SEM image. If the distortion variable is less than the preset threshold, it is determined that the SEM image correction is completed. Therefore, the design layout of the sample to be measured and the SEM image can be first aligned in the center. Then, the key point pairs are determined based on the image units in the design layout and the SEM image. Then, the SEM image is corrected based on the key point pairs. Since the image units in the SEM image of the sample to be measured and the image units in the design layout can be kept consistent as much as possible, the determined key point pairs are 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.

[0105] As shown in Figure 6 The present application provides an electronic device 600, which comprises a processor 601 and a memory 602 storing computer program instructions. When the processor 601 executes the computer program instructions, the image correction method described above is realized.

[0106] The present application provides a computer readable storage medium, which stores computer program instructions. When the computer program instructions are executed by a processor, the image correction method described above is realized.

[0107] It should be understood that the specific features, operations and details described above with respect to the method of the present application can be similarly applied to the device and system of the present application, or vice versa. In addition, each step of the method of the present application described above can be performed by the corresponding component or unit of the device or system of the present application.

[0108] It should be understood that each module / unit of the device of the present application can be realized by software, hardware, firmware or a combination thereof, in whole or in part. Each module / unit can be embedded in the processor of the computer device or independent of the processor in hardware or firmware form, or stored in the memory of the computer device in software form to be invoked by the processor to perform the operations of each module / unit. Each module / unit can be realized as an independent component or module, or two or more modules / units can be realized as a single component or module.

[0109] In one embodiment, a computer device is provided, which includes a memory and a processor, the memory having stored thereon computer instructions executable by the processor, the computer instructions, when executed by the processor, instructing the processor to perform steps of the method of an embodiment of the present application. The computer device can be broadly a server, a terminal, or any other electronic device with necessary computing and / or processing capability. In one embodiment, the computer device can include a processor, a memory, a network interface, a communication interface, etc. connected by a system bus. The processor of the computer device can be configured to provide necessary computing, processing and / or control capability. The memory of the computer device can include a non-volatile storage medium and an internal memory. The non-volatile storage medium can have stored therein or thereon an operating system, a computer program, etc. The internal memory can provide an environment for running of the operating system and the computer program in the non-volatile storage medium. The network interface and the communication interface of the computer device can be configured to connect and communicate with external devices through a network. The computer program, when executed by the processor, performs steps of the method of the present application.

[0110] The present application can be implemented as a computer readable storage medium having stored thereon a computer program which, when executed by a processor, causes steps of the method of an embodiment of the present application to be performed. In one embodiment, the computer program is distributed over a plurality of computer devices or processors coupled to a network, such that the computer program 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, can be performed by a single computer device or processor, or by two or more computer devices or processors. One or more method steps / operations can be performed by one or more computer devices or processors, and one or more other method steps / operations can be performed by one or more other computer devices or processors. One or more computer devices or processors can perform a single method step / operation, or perform two or more method steps / operations.

[0111] As will be appreciated by one of ordinary skill in the art, the steps of the methods of the present application can be directed to relevant hardware, such as computer devices or processors, by way of computer program instructions. Computer program instructions can be stored in non-transitory computer-readable storage media, which when executed, cause the steps of the present application to be performed. Depending on the situation, any of the references to memory, storage, databases, or other media can include non-volatile and / or volatile memory. Examples of non-volatile memory include read only memory (ROM), programmable ROM (PROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), flash memory, magnetic tapes, floppy disks, magnetic disks, magneto-optical disks, optical disks, solid-state disks, etc. Examples of volatile memory include random access memory (RAM), external cache memory, etc.

[0112] Any of the technical features described above can be combined. Although not all possible combinations of the technical features are described, any combination of the technical features should be considered to be within the scope of the present description, as long as such a combination does not result in a contradiction.

[0113] Finally, it should be noted that the above-described embodiments are merely intended to illustrate the technical solutions of the present application, not to limit the technical solutions of the present application; although the present application has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that they can still make modifications to the technical solutions recorded in the above embodiments, or make equivalent replacements to some or all of the technical features; and such modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An image correction method, characterized in that, include: The design layout of the sample to be tested is aligned with the scanning electron microscope (SEM) image at the center. Based on the design layout and the image units in the SEM image, key point pairs are determined; Based on the key point pairs, the SEM image is corrected to obtain a corrected SEM image; Based on the design layout and the corrected SEM image, the distortion variables are determined; If the distortion is less than a preset threshold, the SEM image correction is determined to be complete. The step of determining key point pairs based on the design layout and image units in the SEM image includes: With the geometric centers of the design layout and SEM image aligned, a rectangular coordinate system O-XY is established with the geometric center as the origin O. In the XY plane, an image unit in the SEM image that is offset from the design layout by at least one cycle is selected as the first image unit; Select a second image unit on the design layout that corresponds to the position of the first image unit; Select one of the coordinate points at the same position in the first image unit and the second image unit as the key point pair; The step of selecting an image unit in the SEM image that is offset from the design layout by at least one period relative to the design layout within the XY plane as the first image unit includes: In the first direction within the XY plane, an image unit in the SEM image that is offset from the design layout by at least one cycle is selected as the first image unit; In the second direction within the XY plane, an image unit in the SEM image that is offset by at least one cycle relative to the design layout is selected as the first image unit.

2. The image correction method as described in claim 1, characterized in that, After determining the distortion variables based on the design layout and the corrected SEM image, the method further includes: If the distortion is greater than or equal to a preset threshold, based on the design layout and the corrected SEM image, return to the step of determining key point pairs.

3. The image correction method as described in claim 1, characterized in that, The step of correcting the SEM image based on the key point pairs to obtain a corrected SEM image includes: Based on the key point pairs, correction parameters are determined, wherein the correction parameters include at least one of the following: rotation parameters, scaling parameters, and translation parameters; The SEM image is processed according to the correction parameters to determine the corrected SEM image.

4. The method as described in claim 1, characterized in that, The determination of distortion variables based on the design layout and the corrected SEM image includes: Determine the first first-order origin moment coordinates of each first image unit in the corrected SEM image and the second first-order origin moment coordinates of each second image unit in the design layout; The corrected SEM image and the corresponding first-order origin moment coordinates and second-order origin moment coordinates in the design layout are processed to determine the distortion variables.

5. The image correction method as described in claim 4, characterized in that, The step of processing the corrected SEM image and the corresponding first-order origin moment coordinates and second-order origin moment coordinates in the design layout to determine the distortion includes: The corrected SEM image and the design layout are segmented in the same way to obtain corresponding first sub-images and second sub-images; The first first-order origin moment coordinates of the first image unit contained in each first sub-image and the second first-order origin moment coordinates of the second image unit contained in each second sub-image are respectively averaged to determine the distortion between each first sub-image and the corresponding second sub-image.

6. The image correction method as described in claim 1, characterized in that, The step of determining the end of SEM image correction includes: Given multiple distorted variables, determine the difference between two consecutive distorted variables; If any difference is negative, the SEM image correction is considered complete.

7. An image correction device, characterized in that, The device includes: The alignment module is used to center-align the design layout of the sample to be tested with the scanning electron microscope (SEM) image. The first determining module is used to determine key point pairs based on the design layout and image units in the SEM image; The correction module is used to correct the SEM image based on the key point pairs to obtain a corrected SEM image; The second determining module is used to determine the distortion variables based on the design layout and the corrected SEM image; The third determining module is used to determine that the SEM image correction is completed when the distortion is less than a preset threshold. The first determining module includes: an establishment unit for establishing a rectangular coordinate system O-XY with the geometric center as the origin O, provided that the geometric centers of the design layout and the SEM image are aligned; a first selection unit for selecting an image unit in the SEM image that is offset from the design layout by at least one cycle as a first image unit in the XY plane; a second selection unit for selecting a second image unit on the design layout at a position corresponding to the first image unit; and a third selection unit for selecting one of the coordinate points at the same position in the first image unit and the second image unit as a key point pair. Specifically, the first selection unit is used to: select an image unit in the SEM image that is offset from the design layout by at least one period in a first direction within the XY plane as a first image unit; and select an image unit in the SEM image that is offset from the design layout by at least one period in a second direction within the XY plane as a first image unit.

8. An electronic device, characterized in that, The electronic device includes: a processor and a memory storing computer program instructions; When the processor executes the computer program instructions, it implements the image correction method as described in any one of claims 1-6.

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