Method, device and storage medium for adjusting scanning electron microscope image

Abstract

The present application relates to the field of image processing technology, and discloses a method, device and storage medium for adjusting a scanning electron microscope image. The method includes: performing image acquisition on the upper focal plane and the lower focal plane of the scanning electron microscope to obtain a first image and a second image; performing Fourier transform on the first image and the second image to obtain a first frequency domain image and a second frequency domain image; analyzing the proportion of high-frequency components in the first frequency domain image and the second frequency domain image to obtain a first high-frequency proportion and a second high-frequency proportion; determining the adjustment type, adjustment direction and adjustment step length according to the first high-frequency proportion and the second high-frequency proportion; and adjusting the scanning electron microscope image based on the adjustment type, adjustment direction and adjustment step length. Using the scheme of the present application, an adjustment strategy for the scanning electron microscope image can be automatically given, which can reduce the dependence on the operator's experience and skills and improve the adjustment accuracy.

Description

Technical Field

[0001] The present application generally relates to the field of image processing technology. More specifically, the present application relates to a method for adjusting a scanning electron microscope image, an electronic device and a computer-readable storage medium. Background Art

[0002] Scanning Electron Microscope (SEM) is an instrument that uses a finely focused electron beam to bombard the sample surface, and generates secondary electrons and backscattered electrons through the interaction between electrons and samples to observe and analyze the sample surface or fracture morphology. It has the characteristics of high resolution, large depth of field, strong three-dimensional image, etc., and can provide sample morphology, structure, composition and crystallography information.

[0003] In scanning electron microscopy, the adjustment of focus and astigmatism is a very important step, which together determine the quality and resolution of the final image. Through precise focusing and effective astigmatism correction, a clearer and more accurate image of the sample surface can be obtained. In actual operation, the adjustment of focus and astigmatism can be completed by slowly turning the focus knob and the astigmatism knob. This process may require repeated adjustment and focusing, and observing the image changes until the image is clear and deformed, which requires the operator to have certain experience and skills. However, the operator's perception and reaction may be biased, which results in the quality of the final image not being optimized and the adjustment accuracy being low. At the same time, the results of each manual adjustment may be different, which affects the repeatability of the experiment, resulting in the need to repeat the experiment many times to obtain consistent results, which not only reduces the experimental efficiency, but also may cause waste of sample and equipment resources.

[0004] In view of this, there is an urgent need to provide a solution for adjusting the scanning electron microscope image, so as to improve the adjustment accuracy, improve the work efficiency and reduce the waste of sample and equipment resources. Summary of the invention

[0005] In order to at least solve one or more of the technical problems mentioned above, the present application proposes a solution for adjusting a scanning electron microscope image in the following aspects.

[0006] In a first aspect, the present application provides a method for adjusting a scanning electron microscope image, comprising: performing image acquisition on an upper focal plane and a lower focal plane of the scanning electron microscope to obtain a first image and a second image; performing Fourier transform on the first image and the second image to obtain a first frequency domain image and a second frequency domain image; analyzing the proportion of high-frequency components in the first frequency domain image and the second frequency domain image to obtain a first high-frequency proportion and a second high-frequency proportion; determining an adjustment type, an adjustment direction, and an adjustment step according to the first high-frequency proportion and the second high-frequency proportion; and adjusting the scanning electron microscope image based on the adjustment type, adjustment direction, and adjustment step.

[0007] In some embodiments, analyzing the proportion of high-frequency components in the first frequency domain image and the second frequency domain image to obtain a first high-frequency proportion and a second high-frequency proportion includes: performing a logarithmic transformation on the first frequency domain image and the second frequency domain image to obtain a first logarithmic image and a second logarithmic image; performing a binarization operation on the first logarithmic image and the second logarithmic image to obtain a first binary image and a second binary image; analyzing the proportion of foreground pixels in the first binary image and the second binary image to obtain the first high-frequency proportion and the second high-frequency proportion.

[0008] In some embodiments, determining the adjustment type based on the first high-frequency proportion and the second high-frequency proportion includes: determining the relative deviation between the first high-frequency proportion and the second high-frequency proportion; determining whether the absolute value of the relative deviation is greater than or equal to a preset threshold; when the absolute value of the relative deviation is greater than or equal to the preset threshold, determining that the adjustment type is adjusting focus; when the absolute value of the relative deviation is less than the preset threshold, determining that the adjustment type is adjusting astigmatism.

[0009] In some embodiments, when it is determined that the adjustment type is to adjust the focus, determining the adjustment direction includes: determining whether the relative deviation is greater than 0; when the relative deviation is greater than 0, determining that the adjustment direction is to increase the focus value; when the relative deviation is less than or equal to 0, determining that the adjustment direction is to reduce the focus value.

[0010] In some embodiments, when it is determined that the adjustment type is to adjust the focus, determining the adjustment step includes: determining the relative deviation and the adjustment step of the previous adjustment of the focus of the scanning electron microscope as the reference deviation and the reference step; determining whether the relative deviation and the reference deviation are of different signs; when the relative deviation and the reference deviation are of different signs, reducing the reference step according to a preset reduction rule to obtain the adjustment step; when the relative deviation and the reference deviation are of the same sign, determining the reference step as the adjustment step.

[0011] In some embodiments, when it is determined that the adjustment type is to adjust astigmatism, determining the adjustment direction includes: dividing the first binary image and the second binary image into regions to obtain a positive X region, a negative X region, a positive Y region, and a negative Y region in the first binary image and the second binary image; analyzing the proportions of foreground pixels in the positive X region, the negative X region, the positive Y region, and the negative Y region to obtain a positive X high frequency proportion, a negative X high frequency proportion, a positive Y high frequency proportion, and a negative Y high frequency proportion of the first binary image and the second binary image; determining a positive X high frequency difference, a negative X high frequency difference, a positive Y high frequency difference, and a negative Y high frequency difference between the first binary image and the second binary image based on the positive X high frequency proportion, the negative X high frequency proportion, the positive Y high frequency proportion, and the negative Y high frequency proportion; and determining the adjustment direction according to the positive X high frequency difference, the negative X high frequency difference, the positive Y high frequency difference, and the negative Y high frequency difference.

[0012] In some embodiments, determining the positive X high frequency difference, the negative X high frequency difference, the positive Y high frequency difference, and the negative Y high frequency difference between the first binary image and the second binary image based on the positive X high frequency proportion, the negative X high frequency proportion, the positive Y high frequency proportion, and the negative Y high frequency proportion includes: calculating the positive X high frequency difference between the positive X high frequency proportion of the first binary image and the positive X high frequency proportion of the second binary image; calculating the negative X high frequency difference between the negative X high frequency proportion of the first binary image and the negative X high frequency proportion of the second binary image; calculating the positive Y high frequency difference between the positive Y high frequency proportion of the first binary image and the positive Y high frequency proportion of the second binary image; calculating the negative Y high frequency difference between the negative Y high frequency proportion of the first binary image and the negative Y high frequency proportion of the second binary image.

[0013] In some embodiments, determining the adjustment direction according to the positive X high frequency difference, the negative X high frequency difference, the positive Y high frequency difference, and the negative Y high frequency difference comprises: when the positive X high frequency difference is greater than 0 and the negative X high frequency difference is less than 0, determining the adjustment direction is to increase the X-direction astigmatism value; when the positive X high frequency difference is less than 0 and the negative X high frequency difference is greater than 0, determining the adjustment direction is to reduce the X-direction astigmatism value; when the positive Y high frequency difference is greater than 0 and the negative Y high frequency difference is less than 0, determining the adjustment direction is to increase the Y-direction astigmatism value; when the positive Y high frequency difference is less than 0 and the negative Y high frequency difference is greater than 0, determining the adjustment direction is to reduce the Y-direction astigmatism value.

[0014] In some embodiments, when it is determined that the adjustment type is to adjust astigmatism, determining the adjustment step includes: calculating an X-direction deviation between the positive X-direction high frequency difference and the negative X-direction high frequency difference, and a Y-direction deviation between the positive Y-direction high frequency difference and the negative Y-direction high frequency difference; determining an X-direction deviation, a Y-direction deviation, and an adjustment step of a previous adjustment of the astigmatism of the scanning electron microscope as a reference X-direction deviation, a reference Y-direction deviation, and a reference step; and determining the adjustment step according to whether the X-direction deviation and the reference X-direction deviation have different signs, and whether the Y-direction deviation and the reference Y-direction deviation have different signs.

[0015] In some embodiments, determining the adjustment step length according to whether the X-direction deviation and the reference X-direction deviation have different signs, and whether the Y-direction deviation and the reference Y-direction deviation have different signs includes: determining whether the X-direction deviation and the reference X-direction deviation have different signs, and whether the Y-direction deviation and the reference Y-direction deviation have different signs; when the X-direction deviation and the reference X-direction deviation have different signs or the Y-direction deviation and the reference Y-direction deviation have different signs, reducing the reference step length according to a preset reduction rule to obtain the adjustment step length; when the X-direction deviation and the reference X-direction deviation have the same sign and the Y-direction deviation and the reference Y-direction deviation have the same sign, determining the reference step length as the adjustment step length.

[0016] In some embodiments, performing Fourier transform on the first image and the second image to obtain a first frequency domain image and a second frequency domain image includes: processing the first image and the second image using a Hanning window function to obtain processed first and second images; performing Fourier transform on the processed first and second images to obtain first and second frequency domain images.

[0017] In a second aspect, the present application provides an electronic device, comprising: a processor; and a memory storing program instructions for adjusting a scanning electron microscope image, wherein when the program instructions are executed by the processor, the method described in the first aspect and its multiple embodiments are implemented.

[0018] In a third aspect, the present application provides a computer-readable storage medium having stored thereon program instructions for adjusting a scanning electron microscope image, wherein when the program instructions are executed by a processor, the method described in the first aspect and its multiple embodiments are implemented.

[0019] By using the method for adjusting the scanning electron microscope image as provided above, the first high-frequency proportion and the second high-frequency proportion can be obtained by analyzing the proportion of high-frequency components in the first frequency domain image of the upper focal plane and the second frequency domain image of the lower focal plane. Thereafter, the adjustment type, adjustment direction and adjustment step can be determined according to the first high-frequency proportion and the second high-frequency proportion, thereby achieving the adjustment of the scanning electron microscope image. Using the scheme of the present application, an adjustment strategy for the scanning electron microscope image can be automatically given, which can reduce the dependence on the operator's experience and skills and reduce the interference of human factors in the adjustment process. As a result, the adjustment accuracy can be improved, and it is ensured that the results of each experiment are more consistent, thereby improving the experimental efficiency and saving samples and equipment resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] By reading the detailed description below with reference to the accompanying drawings, the above and other purposes, features and advantages of the exemplary embodiments of the present application will become easy to understand. In the accompanying drawings, several embodiments of the present application are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein:

[0021] Figure 1 A schematic diagram showing the presence of defocus and astigmatism in scanning electron microscope imaging;

[0022] Figure 2 A schematic diagram showing the absence of defocus and astigmatism in scanning electron microscope imaging;

[0023] Figure 3 Exemplary frequency domain images of SEM images of different resolutions are shown;

[0024] Figure 4 Exemplary frequency domain images of SEM images showing different focusing and astigmatism;

[0025] Figure 5 A schematic diagram of the divided regions of the frequency domain image is shown;

[0026] Figure 6 An exemplary flow chart of a method for adjusting a scanning electron microscope image according to an embodiment of the present application is shown;

[0027] Figure 7 An exemplary frequency domain image of a first image and a second image according to an embodiment of the present application is shown;

[0028] Figure 8 An exemplary processing effect diagram of the Hanning window function of an embodiment of the present application is shown;

[0029] Fig. 9 Shows Figure 6 An exemplary flow chart of a step in the process;

[0030] Fig.10 Shows Figure 6 An exemplary flow chart of another step in

[0031] Fig.11 An exemplary structural block diagram of an electronic device according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0033] It should be understood that when the terms "first", "second", "third" and "fourth" are used in the claims, the specification and the drawings of the present application, they are only used to distinguish different objects, rather than to describe a specific order. The terms "include" and "comprise" used in the specification and claims of the present application indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections.

[0034] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this application specification and claims, unless the context clearly indicates otherwise, the singular forms of "a", "an" and "the" are intended to include plural forms. It should also be further understood that the term "and / or" used in this application specification and claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0035] As used in this specification and claims, the term "if" can be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0036] The specific implementation of the present application is described in detail below with reference to the accompanying drawings.

[0037] For ease of understanding, before introducing the solution of the present application in detail, the working principle, focusing and astigmatism of the scanning electron microscope (hereinafter referred to as SEM) involved in the present application are first introduced.

[0038] The working principle of the scanning electron microscope is to use an electron gun to emit an electron beam, which is focused into a thin beam by an electromagnetic lens and then scanned on the sample surface in a grid-like manner. The incident electrons interact with the sample to stimulate secondary electrons, backscattered electrons, X-rays and other signals, which are detected and amplified by the corresponding detectors, and finally form a microscopic image of the sample surface on the display screen.

[0039] Focusing means changing the convergence of the electron beam by adjusting the current of the objective lens so that the electron beam can form a small focal point on the surface of the sample. This focal point scans the surface of the sample, stimulating signals such as secondary electrons and backscattered electrons, which are collected by the detector and converted into image signals. The accuracy of focusing directly affects the resolution and clarity of the image. In actual operation, focusing can be achieved by adjusting the current of the objective lens. Therefore, in the case where the adjustment type below is to adjust the focus, the units of the focus value and adjustment step mentioned are the same as the current unit of the objective lens, for example, it can be milliamperes (mA).

[0040] Astigmatism refers to the phenomenon that the electron beam deflects after passing through the sample. This deflection will cause the electron beam spot to be slightly elliptical, affecting the clarity of the image. When changing from underfocus, focus, to overfocus, the image will be deformed by stretching to the left and right. In order to reduce the influence of astigmatism, scanning electron microscopes usually use an astigmatism corrector, i.e., an stigmatism corrector. The stigmatism corrector consists of two sets of orthogonal coils (X-direction coils and Y-direction coils). In actual operation, the required magnetic field can be generated by adjusting the voltage in these two sets of coils to correct the astigmatism of the electron beam, thereby improving the imaging quality. Therefore, in the case where the adjustment type below is to adjust the astigmatism, the units of the astigmatism value and the adjustment step mentioned are the same as the voltage unit of the stigmatism corrector, for example, it can be volts (V).

[0041] Here, you can refer to Figure 1 and 2 Understand the focus and astigmatism in SEM imaging. Here, Figure 1 A schematic diagram showing the presence of defocus (i.e., the electron beam is not focused on the sample surface) and astigmatism in SEM imaging. Figure 2 Schematic diagram showing the absence of defocus and astigmatism in SEM imaging. It can be understood that Figure 1 and 2 The X and Y axes shown in FIG. 5 define the spatial coordinates of the SEM image.

[0042] like Figure 1As shown in Figure 2, in SEM imaging, if there is astigmatism, the electron beam will focus on the sample instead of forming a perfect circular spot, but an elliptical spot (e.g. Figure 1 The shape and direction of the ellipse points can indicate the direction and degree of astigmatism. Figure 1 It can also be seen that when the image plane moves from the overfocus position (i.e. Figure 1 The focal plane moves from the upper to the middle focal plane to the out-of-focus position (i.e. Figure 1 When moving the image in the middle or lower focal plane) or vice versa, the stretch in the image will rotate 90°.

[0043] like Figure 1 As shown, the upper focal plane refers to the plane formed when the focus of the electron beam is located above the sample surface. In this case, the image of the sample collected can be called the upper focal plane image. Since the electron cloud formed by the electron beam above the sample interacts with the sample to produce fewer secondary electrons, the upper focal plane image usually appears darker at the edges and brighter at the center. The lower focal plane refers to the plane formed when the focus of the electron beam is located below the sample surface. In this case, the image of the sample collected can be called the lower focal plane image. Since the electron cloud formed by the electron beam below the sample interacts with the sample to produce more secondary electrons, while the electron interaction in the central area is less, the lower focal plane image usually appears brighter at the edges and darker at the center.

[0044] In practice, adjusting the focus of an SEM image can be thought of as moving the focal plane of the image (i.e., the plane where the electron beam is focused on the sample) up or down. Adjusting the astigmatism of an SEM image can be thought of as moving the focal points of the electron beams in different directions closer together. When the image is focused and there is no astigmatism, the electron beams in different directions will converge at a point on the sample surface (e.g., Figure 2 The focal plane of the image is moved up or down without noticeable stretching in the upper or lower focal plane images.

[0045] Next, combine Figure 3 and 4 The Fourier transform of the scanning electron microscope image involved in this application is introduced. Here, Figure 3 are exemplary frequency domain images showing SEM images of different resolutions. Figure 4 are exemplary frequency domain images of SEM images showing different focusing and astigmatism.

[0046] As those skilled in the art know, Fourier transform is a mathematical tool that converts a signal from the time domain (or spatial domain) to the frequency domain. In image processing, Fourier transform can convert an image from the pixel domain (also called the spatial domain) to the frequency domain, where the grayscale value of each pixel (or pixel) of the image is converted into the complex amplitude and phase of the corresponding frequency. The result of Fourier transform is a complex matrix, in which each element represents the amplitude and phase of a specific frequency in the image. Usually, we convert this complex matrix into a visual image based on the amplitude (also called the modulus) of each element, which is the frequency domain image.

[0047] When Fourier transform converts image signals into the frequency domain, the edge areas in the image are represented by high-frequency information in the Fourier transform. Figure 3 As shown in the figure, the upper left side is a clear SEM image without astigmatism, the lower left side is a blurred SEM image without astigmatism, and the right side is the corresponding frequency domain image. Comparing the two frequency domain images on the right, it can be found that when the SEM image is blurred, the feature boundaries in the image will also become blurred, and the high-frequency signal in the frequency domain image will also decrease.

[0048] Next, refer to Figure 4 Understand the effect of different focusing and astigmatism on the frequency domain image. In order to analyze how the frequency domain image changes with different focusing and astigmatism, the frequency domain image can be divided into multiple regions. In actual operation, the frequency domain image can be divided into multiple regions by referring to the azimuth diagram of the stigmator. Figure 5 As shown, Figure 5 a in the figure is a schematic diagram of the frequency domain image. Figure 5 b in the figure is the azimuth diagram of the stigmator. In the azimuth diagram of the stigmator, the regions are divided according to the four directions of positive X (i.e. +X), negative X (i.e. -X), positive Y (i.e. +Y) and negative Y (i.e. -Y), and eight azimuth regions from A to H can be obtained. Referring to the azimuth diagram of the stigmator, the frequency domain image can be divided into eight image regions from R1 to R4 and S1 to S4, and the angle of each image region is 45°. Here, R1 and R2 correspond to the positive X direction, R3 and R4 correspond to the negative X direction, S1 and S2 correspond to the negative Y direction, and S3 and S4 correspond to the positive Y direction.

[0049] Based on this, Figure 4 Specifically, the effects of any two combinations of clarity, no astigmatism, reduced focus value, increased focus value, reduced X-direction astigmatism value, increased X-direction astigmatism value, reduced Y-direction astigmatism value, and increased Y-direction astigmatism value on the scanning electron microscope image and the frequency domain image are shown. Here, reducing or increasing the focus value corresponds to reducing or increasing the current value of the objective lens, reducing or increasing the X-direction astigmatism value corresponds to reducing or increasing the voltage value of the X-direction coil of the stigmatizer, and reducing or increasing the Y-direction astigmatism value corresponds to reducing or increasing the voltage value of the Y-direction coil of the stigmatizer.

[0050] contrast Figure 4 From the three images in the first row in the figure, we can see that, in the absence of astigmatism, increasing or decreasing the focus value will make the SEM image blurry, and the high-frequency signal in the corresponding frequency domain image will decrease, but no stretching occurs. Figure 4 From the five images in the first column, we can find that while maintaining clarity, increasing or decreasing the astigmatism value in the X direction, and increasing or decreasing the astigmatism value in the Y direction, will make the SEM image blurred, and the corresponding frequency domain image will also appear stretched.

[0051] Further, comparison Figure 4 From the right two columns of the second and third rows in the figure, it can be found that when increasing or decreasing the astigmatism value in the X direction, stretching will appear in the S1, S2, S3, and S4 regions in the frequency domain image, that is, in the regions corresponding to the positive Y and negative Y directions. Figure 4 It can also be found from the right two columns of the fourth and fifth rows in that when the Y-direction astigmatism value is increased or decreased, stretching will appear in the R1, R2, R3, and R4 regions in the frequency domain image, that is, in the regions corresponding to the positive X and negative X directions. It can be seen that the direction of stretching in the frequency domain image is orthogonal to the direction of stretching in the SEM image.

[0052] After introducing the effects of different focusing and astigmatism on frequency domain images, next, Figure 6 The method 600 for adjusting a scanning electron microscope image according to some embodiments of the present application is exemplarily introduced. It is understandable that the method 600 can be executed by any appropriate device with data processing capability, such as but not limited to a processor, a terminal device, and a server.

[0053] like Figure 6 As shown, at step S601, method 600 can perform image acquisition at the upper focal plane and the lower focal plane of the scanning electron microscope to obtain an upper focal plane image (hereinafter referred to as the first image) and a lower focal plane image (hereinafter referred to as the second image). As an example, assume that the focus value is 0.53 mA when the focus of the electron beam is located on the sample surface. In this case, the upper focal plane image can be acquired at the upper focal plane (focus value is (0.53-0.02) mA), and the lower focal plane image can be acquired at the lower focal plane (focus value is (0.53+0.02) mA).

[0054] Next, at step S602, the method 600 may respectively process the first image (eg Figure 7 a in the figure) and the second image (as shown in Figure 7 c in the figure) to perform Fourier transform to obtain the first frequency domain image (as shown in Figure 7b in the figure) and the second frequency domain image (as shown in Figure 7 As shown in d in FIG. 1 ). By observation, it can be found that the first image and the second image show edge features of different clarity, and the first frequency domain image and the second frequency domain image show stretching in different directions. It can be understood that those skilled in the art can select a specific Fourier transform method according to actual needs, for example, a direct Fourier transform, a fast Fourier transform, etc. can be selected, and this application does not limit this.

[0055] In the scheme of the present application, detecting the direction of stretching in the frequency domain image is very important for determining the adjustment direction described below. Therefore, it is necessary to collect more edge features in the first image and the second image. Since there is usually more high-frequency information at the edge, in order to reduce spectrum leakage and increase the accuracy of frequency domain analysis, before Fourier transforming the first image and the second image, the first image and the second image may be preprocessed. For example, the first image and the second image may be processed using a Hanning window function. In this way, the interference of noise on the frequency domain information may be reduced and the high-frequency components may be enhanced. Next, the processed first image and the second image may be Fourier transformed to obtain a first frequency domain image and a second frequency domain image.

[0056] Here, the Hanning window function is a weighted function based on the cosine function and can be expressed by the following formula:

[0057] (1)

[0058] in, is the window function at position The value at is the sample point index in the window, is the length of the window (the number of sample points).

[0059] You can refer to the following Figure 8 Understand the processing effect of the Hanning window function. Figure 8 As shown, Figure 8 a1 and b1 in the figure are scanning electron microscope images. After processing a1 and b1 using the Hanning window function, the processed images can be obtained (such as Figure 8 a2 and b2 in the figure). Figure 8 a3 in is the frequency domain image corresponding to a1, Figure 8 b3 in is the frequency domain image corresponding to b1. Figure 8 a4 in is the frequency domain image corresponding to a2, Figure 8b4 in the figure is the frequency domain image corresponding to b2. It can be observed that in a3 and b3, the direction information is not obvious, and the adjustment direction cannot be distinguished based on this in the process of adjusting the SEM image. On the contrary, in a4 and b4, the high-frequency information is more clearly displayed, and the adjustment direction can be distinguished based on this in the process of adjusting the SEM image.

[0060] Next, at step S603, method 600 may analyze the proportion of high-frequency components in the first frequency domain image and the second frequency domain image, respectively, to obtain a first high-frequency proportion and a second high-frequency proportion. Here, the high-frequency component may be a pixel in the frequency domain image whose pixel value (i.e., amplitude) is greater than a preset threshold (which may be referred to as the first threshold for ease of distinction). The proportion of high-frequency components may be the proportion of pixels in the frequency domain image whose pixel values ​​are greater than the first threshold. In actual operation, those skilled in the art may select a specific value of the first threshold according to actual needs, and may also determine the mean of the pixel values ​​in the frequency domain image as the first threshold, which is not limited in the present application.

[0061] Next, at step S604, the method 600 may determine the adjustment type, adjustment direction, and adjustment step length according to the first high frequency proportion and the second high frequency proportion. The adjustment type, adjustment direction, and adjustment step length may generally be determined according to the relative deviation between the first high frequency proportion and the second high frequency proportion. Here, the adjustment type may include adjusting focus and adjusting astigmatism.

[0062] In the case where the adjustment type is to adjust the focus, the adjustment direction may include increasing the focus value and decreasing the focus value. Increasing the focus value may move the focal plane downward, and decreasing the focus value may move the focal plane upward. The adjustment step may indicate the amount of change in the focus value along the adjustment direction. Similarly, in the case where the adjustment type is to adjust the astigmatism, the adjustment direction may include increasing the astigmatism value in the X direction, decreasing the astigmatism value in the X direction, increasing the astigmatism value in the Y direction, and decreasing the astigmatism value in the Y direction. Increasing or decreasing the astigmatism value in the X direction may change the stretching of the area corresponding to the positive Y and negative Y directions in the frequency domain image. Increasing or decreasing the astigmatism value in the Y direction may change the stretching of the area corresponding to the positive X and negative X directions in the frequency domain image. The adjustment step may indicate the amount of change in the astigmatism value along the adjustment direction.

[0063] Finally, at step S605, method 600 can adjust the SEM image based on the adjustment type, adjustment direction, and adjustment step length. In one embodiment, the device performing method 600 can be in communication with the SEM and can transmit the adjustment type, adjustment direction, and adjustment step length to the SEM to adjust the focus or astigmatism of the SEM image.

[0064] Combined with the description of focus and astigmatism in scanning electron microscope imaging in the previous text, it can be known that when the adjustment type is to adjust the focus, the focus of the scanning electron microscope image can be adjusted by adjusting the current value of the objective lens according to the adjustment step. Further, the current value of the objective lens can be increased or decreased according to the adjustment direction. When the adjustment type is to adjust the astigmatism, the astigmatism of the scanning electron microscope image can be adjusted by adjusting the voltage value of the stigmator according to the adjustment step. Further, when the adjustment direction is to increase the astigmatism value in the X direction or to reduce the astigmatism value in the X direction, the voltage value of the X direction coil can be increased or decreased according to the adjustment step. When the adjustment direction is to increase the astigmatism value in the Y direction or to reduce the astigmatism value in the Y direction, the voltage value of the Y direction coil can be increased or decreased according to the adjustment step.

[0065] In practical applications, when a scanning electron microscope is used to detect a sample, the sample can be first correctly fixed on the sample stage and the correct position of the sample can be found. Then, the method 600 for adjusting the scanning electron microscope image provided by the present application is used to automatically adjust the focus and astigmatism of the scanning electron microscope image, which can reduce the dependence on the operator's experience and skills and reduce the interference of human factors in the adjustment process. As a result, the adjustment accuracy can be improved and the results of each experiment can be ensured to be more consistent, thereby improving the experimental efficiency and saving samples and equipment resources.

[0066] It is understandable that, when the method 600 for adjusting a scanning electron microscope image provided by the present application is used to automatically adjust the focus and astigmatism of the scanning electron microscope image, steps S601 to S605 can be executed repeatedly in a loop until a predetermined cutoff condition is reached and the loop is stopped to obtain an ideal image state. In one embodiment, the cutoff condition can be that the adjustment step length is equal to the preset minimum step length. In actual operation, those skilled in the art can set the specific value of the preset minimum step length according to actual needs, and the present application does not make specific limitations on this.

[0067] It can also be understood that those skilled in the art can set different preset minimum step sizes for different adjustment types according to actual needs. For example, the preset minimum step size for adjusting focus can be set to 0.01, and the preset minimum step size for adjusting astigmatism can be set to 0.5. This application does not make specific limitations on this.

[0068] Fig. 9 is an exemplary flow chart showing the analysis of the proportion of high frequency components in the first frequency domain image and the second frequency domain image according to an embodiment of the present application. It can be seen from the following description that: Fig. 9 The process shown in can be combined with the previous Figure 6 The step S603 is a visual representation of the above. Figure 6 The description can also be applied to Fig. 9Description.

[0069] like Fig. 9 As shown, at step S603 - 1 , the method 600 may perform logarithmic transformation on the first frequency domain image and the second frequency domain image to obtain a first logarithmic image and a second logarithmic image.

[0070] Since the dynamic range of the Fourier coefficients is too large, if the Fourier coefficients are mapped to the first frequency domain image and the second frequency domain image using linear mapping, it may cause the smaller Fourier coefficients to gather at the low end of the grayscale value and become black dots, while the larger Fourier coefficients gather at the high end of the grayscale value and become white dots, so that these smaller or larger values ​​cannot be observed on a linear scale. In order to facilitate the display of all Fourier coefficients, a logarithmic transformation can be used to map the first frequency domain image and the second frequency domain image in linear size to a logarithmic size. In actual operation, the following formula can be used to perform logarithmic transformation on the first frequency domain image and the second frequency domain image:

[0071] (2)

[0072] Among them, c is the scaling factor, r is the pixel value in the frequency domain image (i.e., the amplitude), and s is the pixel value in the logarithmic image (i.e., the amplitude after logarithmic transformation).

[0073] Next, at step S603 - 2 , the method 600 may perform a binarization operation on the first logarithmic image and the second logarithmic image to obtain a first binary image and a second binary image.

[0074] In actual operation, a fixed threshold value may be used to perform a binarization operation on the first logarithmic image and the second logarithmic image. Here, the specific value of the fixed threshold value may be selected according to actual needs. For example, a fixed threshold value of 90 may be selected. In this case, pixels in the logarithmic image (for example, the first logarithmic image and the second logarithmic image) whose pixel values ​​are greater than or equal to 90 may be set to 255, and pixels whose pixel values ​​are less than 90 may be set to 0. In one embodiment, the following formula may be used to perform a binarization operation on the logarithmic image to obtain a binary image: :

[0075] (3)

[0076] In addition to the above-mentioned use of a fixed threshold to perform a binarization operation on the first logarithmic image and the second logarithmic image, the mean of the logarithmic image can also be used as the threshold of the binarization operation. Generally, the mean of all pixels in the logarithmic image can be calculated as the threshold of the binarization operation, and the pixels in the logarithmic image whose pixel values ​​are greater than or equal to the threshold can be set to 255, and the pixels whose pixel values ​​are less than the threshold can be set to 0. In one embodiment, the following formula can be used to perform a binarization operation on the logarithmic image to obtain a binary image :

[0077] (4)

[0078] in, is a logarithmic image, m and n are both integers greater than 0, and m*n is The number of pixels, is the threshold value.

[0079] After obtaining a binary image (e.g., a first binary image, a second binary image), in order to smooth out some noise, a 3*3 convolution kernel with all elements set to 1 can be used to perform a convolution operation on the binary image to obtain a convolution image. Thereafter, by performing image comparison between the convolution image and the binary image according to pixel positions, pixels with pixel values ​​of 255 in both the convolution image and the binary image can be found as candidate pixels. Next, the candidate pixels are retained in the binary image and the pixel values ​​of the remaining pixels are set to 0 to obtain the final binary image.

[0080] Finally, at step S603-3, the method 600 may analyze the proportion of foreground pixels in the first binary image and the second binary image to obtain a first high frequency proportion and a second high frequency proportion. Here, the foreground pixel may be a pixel with a pixel value of 255 in the binary image. The proportion of foreground pixels may be a ratio of pixels with a pixel value of 255 in the binary image.

[0081] Fig.10 It is an exemplary flow chart showing the determination of the adjustment type according to an embodiment of the present application. It can be seen from the following description that Fig.10 The process shown in can be combined with the previous Figure 6 The step S604 is a visual representation of the above. Figure 6 The description can also be applied to Fig.10 Description.

[0082] like Fig.10 As shown, at step S604-1, the method 600 may determine the relative deviation between the first high frequency ratio and the second high frequency ratio. In actual operation, the relative deviation may be determined by the following formula: :

[0083] (5)

[0084] in, is the first high frequency ratio, It is the second high frequency proportion.

[0085] Next, at step S604-2, method 600 can determine whether the absolute value of the relative deviation is greater than or equal to a preset threshold (which can be called a second threshold for easy distinction), and select to execute step S604-3 or S604-4 according to the determination result. Here, the second threshold is an empirical value, and those skilled in the art can select the specific value or value range of the second threshold according to actual needs and scanning electron microscope adjustment experience. Preferably, the value range of the second threshold can be (0, 0.1], that is, greater than 0 and less than or equal to 0.1. Further, the specific value of the second threshold can be selected as 0.05, 0.06 or 0.07, etc.

[0086] In step S604 - 3 , when the absolute value of the relative deviation is greater than or equal to the second threshold, the method 600 determines that the adjustment type is focus adjustment.

[0087] In the solution of the present application, when it is determined that the adjustment type is to adjust the focus, the adjustment direction can be further determined. Specifically, it can be determined whether the relative deviation is greater than 0. When the relative deviation is greater than 0, the adjustment direction can be determined to increase the focus value. On the contrary, when the relative deviation is less than or equal to 0, the adjustment direction can be determined to decrease the focus value.

[0088] In the scheme of the present application, when it is determined that the adjustment type is to adjust the focus, the adjustment step S can be further determined. Specifically, the relative deviation Last_R and the adjustment step Last_S of the previous focus adjustment of the scanning electron microscope can be determined as the reference deviation and the reference step. Then, it can be determined whether the aforementioned relative deviation R and the reference deviation Last_R are of different signs. In the case where the relative deviation R and the reference deviation Last_R are of different signs, that is, when R*Last_R<0, the reference step Last_S can be reduced according to the preset reduction rule to obtain the adjustment step S. On the contrary, in the case where the relative deviation R and the reference deviation Last_R are of the same sign, that is, when R*Last_R>0, the reference step Last_S can be determined as the adjustment step S.

[0089] In step S604 - 4 , when the absolute value of the relative deviation is less than the second threshold, the method 600 determines that the adjustment type is adjusting astigmatism.

[0090] In the solution of the present application, when it is determined that the adjustment type is to adjust the astigmatism, the adjustment direction can be further determined. Specifically, the first binary image and the second binary image can be divided into regions with reference to the orientation diagram of the aforementioned stigmator to obtain the positive X region (R1 and R2), the negative X region (R3 and R4), the positive Y region (S3 and S4), and the negative Y region (S1 and S2) in the first binary image and the second binary image. Then, the proportion of foreground pixels in the positive X region, the negative X region, the positive Y region, and the negative Y region can be analyzed to obtain the positive X high frequency proportion of the first binary image. , Negative X high frequency ratio , positive Y high frequency ratio and negative Y high frequency ratio , and the positive X high frequency ratio of the second binary image , Negative X high frequency ratio , positive Y high frequency ratio and negative Y high frequency ratio .

[0091] Next, the positive X high frequency difference between the first binary image and the second binary image may be determined based on the positive X high frequency ratio, the negative X high frequency ratio, the positive Y high frequency ratio, and the negative Y high frequency ratio. , negative X high frequency difference , positive Y high frequency difference and negative Y high frequency difference Specifically, the positive X high frequency ratio of the first binary image can be calculated The positive X high frequency ratio of the second binary image The positive X high frequency difference between ; Calculate the negative X high frequency ratio of the first binary image The negative X high frequency ratio of the second binary image The negative X high frequency difference between ; Calculate the positive Y high frequency ratio of the first binary image The positive Y high frequency ratio of the second binary image The positive Y high frequency difference between ; and calculate the negative Y high frequency ratio of the first binary image The negative Y high frequency ratio of the second binary image Negative Y high frequency difference between .

[0092] In actual operation, the following formula can be used to determine the positive X high frequency difference between the first binary image and the second binary image: , negative X high frequency difference , positive Y high frequency difference and negative Y high frequency difference :

[0093] (6)

[0094] Finally, the adjustment direction can be determined according to the positive X high frequency difference, the negative X high frequency difference, the positive Y high frequency difference and the negative Y high frequency difference. Greater than 0 and negative X high frequency difference When it is less than 0, it can be determined that the adjustment direction is to increase the X-direction astigmatism value. Less than 0 and negative X high frequency difference When it is greater than 0, it can be determined that the adjustment direction is to reduce the X-direction astigmatism value. Greater than 0 and negative Y high frequency difference When it is less than 0, it can be determined that the adjustment direction is to increase the Y-direction astigmatism value. Less than 0 and negative Y high frequency difference When it is greater than 0, the adjustment direction can also be determined to reduce the Y-direction astigmatism value.

[0095] In the solution of the present application, when the adjustment type is determined to be the adjustment of astigmatism, the adjustment step length can be further determined. Specifically, the positive X high frequency difference can be calculated first High frequency difference with negative X The X-direction deviation between , and negative Y high frequency difference High frequency difference with positive Y Y deviation between In actual operation, the following formula can be used to calculate the X-direction deviation and the Y-direction deviation:

[0096] (7)

[0097] Then, the X-direction deviation, Y-direction deviation and adjustment step length of the last adjustment of the astigmatism of the scanning electron microscope can be determined as the reference X-direction deviation, the reference Y-direction deviation and the reference step length. Then, the adjustment step length can be determined according to whether the X-direction deviation and the reference X-direction deviation have different signs, and whether the Y-direction deviation and the reference Y-direction deviation have different signs.

[0098] In the scheme of the present application, the adjustment step length is determined according to whether the X-direction deviation and the reference X-direction deviation have different signs, and whether the Y-direction deviation and the reference Y-direction deviation have different signs. Specifically, it can be determined first whether the X-direction deviation and the reference X-direction deviation have different signs, and whether the Y-direction deviation and the reference Y-direction deviation have different signs. In the case where the X-direction deviation and the reference X-direction deviation have different signs or the Y-direction deviation and the reference Y-direction deviation have different signs, the reference step length can be reduced according to a preset reduction rule to obtain the adjustment step length. Conversely, in the case where the X-direction deviation and the reference X-direction deviation have the same sign and the Y-direction deviation and the reference Y-direction deviation have the same sign, the reference step length can be determined as the adjustment step length.

[0099] It can be understood that those skilled in the art can set the above-mentioned preset reduction rule according to actual needs. For example, the preset reduction rule can be set to reduce to half of the reference step length, or the preset reduction rule can be set to reduce to one third of the reference step length, or the preset reduction rule can be set to reduce to one quarter of the reference step length, etc. The present application does not make any specific limitation on this.

[0100] It is also understandable that, in the multiple adjustments of the focus and astigmatism of the scanning electron microscope image, when the current adjustment is the first adjustment in the entire cycle, the adjustment step length of the previous adjustment of the scanning electron microscope image cannot be obtained as a reference step length. Therefore, those skilled in the art can set the initial adjustment step length according to actual needs, so as to determine the initial adjustment step length as the adjustment step length of the first adjustment.

[0101] It is understandable that those skilled in the art can set different initial adjustment step sizes for different adjustment types according to actual needs. For example, the initial adjustment step size for adjusting focus can be set to 1, and the initial adjustment step size for adjusting astigmatism can be set to 3. This application does not make any specific limitations on this.

[0102] Next, combine Fig.11 An electronic device 1100 provided in an embodiment of the present application is exemplarily introduced. Fig.11 As shown, the electronic device 1100 of the embodiment of the present application may include a processor 1101 , a memory 1102 and a communication bus 1103 .

[0103] In the process of a specific embodiment, the processor 1101 may be at least one of an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing image processing device (DSPD), a programmable logic image processing device (PLD), a field programmable gate array (FPGA), a CPU, a controller, a microcontroller, and a microprocessor. It can be understood that for different devices, the electronic device used to implement the function of the processor may also be other, which is not specifically limited in this embodiment.

[0104] In the embodiment of the present application, the communication bus 1103 is used to realize the connection and communication between the processor 1101 and the memory 1102; the memory 1102 stores program instructions for adjusting the scanning electron microscope image; when the processor 1101 executes the program instructions stored in the memory 1102, the present application is realized. Figures 6 to 10 A method for conditioning a scanning electron microscope image is described.

[0105] Combination of the above Fig.11 An electronic device for adjusting a scanning electron microscope image that can be used to perform the present application is described. It should be understood that the device structure or architecture here is merely exemplary, and the implementation and implementation entity of the present application are not limited thereto, but can be changed without departing from the spirit of the present application. It is understandable that the description of each embodiment in the present disclosure emphasizes the differences between the various embodiments, and the same or corresponding parts can be referenced to each other. For the purpose of brevity, the present disclosure will not repeat them one by one.

[0106] According to the above description in combination with the accompanying drawings, those skilled in the art can also understand that the embodiments of the present application can also be implemented by a software program. Therefore, the present application also provides a computer-readable storage medium. The computer-readable storage medium stores program instructions for controlling the startup of the device, and the program instructions can be used to implement the present application in combination with Figures 6 to 10 A method for conditioning a scanning electron microscope image is described.

[0107] It should be noted that although the operations of the method of the present application are described in a specific order in the accompanying drawings, this does not require or imply that the operations must be performed in this specific order, or that all the operations shown must be performed to achieve the desired results. On the contrary, the steps depicted in the flow chart can be performed in a different order. Additionally or alternatively, some steps can be omitted, multiple steps can be combined into one step, and / or one step can be decomposed into multiple steps.

[0108] Although multiple embodiments of the present application have been shown and described herein, it is obvious to those skilled in the art that such embodiments are provided only by way of example. Those skilled in the art can think of many changes, modifications and alternatives without departing from the thought and spirit of the present application. It should be understood that in the process of practicing the present application, various alternatives to the embodiments of the present application described herein can be adopted. The attached claims are intended to limit the scope of protection of the present application, and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. A method for adjusting a scanning electron microscope image, comprising: Perform image acquisition at the upper focal plane and the lower focal plane of the scanning electron microscope to obtain a first image and a second image; Performing Fourier transform on the first image and the second image to obtain a first frequency domain image and a second frequency domain image; Analyzing the proportions of high-frequency components in the first frequency domain image and the second frequency domain image to obtain a first high-frequency proportion and a second high-frequency proportion; Determining an adjustment type, an adjustment direction, and an adjustment step length according to the first high frequency proportion and the second high frequency proportion; Implementing adjustment of the scanning electron microscope image based on the adjustment type, adjustment direction and adjustment step size; Analyzing the proportion of high-frequency components in the first frequency domain image and the second frequency domain image to obtain a first high-frequency proportion and a second high-frequency proportion includes: Performing logarithmic transformation on the first frequency domain image and the second frequency domain image to obtain a first logarithmic image and a second logarithmic image; Performing a binarization operation on the first logarithmic image and the second logarithmic image to obtain a first binary image and a second binary image; The proportions of foreground pixels in the first binary image and the second binary image are analyzed to obtain the first high-frequency proportion and the second high-frequency proportion.

2. The method according to claim 1, wherein: Determining the adjustment type according to the first high frequency proportion and the second high frequency proportion includes: Determine a relative deviation between the first high frequency proportion and the second high frequency proportion; Determining whether the absolute value of the relative deviation is greater than or equal to a preset threshold; When the absolute value of the relative deviation is greater than or equal to the preset threshold, determining that the adjustment type is focus adjustment; When the absolute value of the relative deviation is smaller than the preset threshold, it is determined that the adjustment type is adjusting astigmatism.

3. The method according to claim 2, wherein when the adjustment type is determined to be focus adjustment, determining the adjustment direction comprises: Determine whether the relative deviation is greater than 0; When the relative deviation is greater than 0, determining that the adjustment direction is to increase the focus value; When the relative deviation is less than or equal to 0, the adjustment direction is determined to be reducing the focus value.

4. The method according to claim 2, wherein when the adjustment type is determined to be focus adjustment, determining the adjustment step size comprises: Determine the relative deviation and adjustment step length of the previous focus adjustment of the scanning electron microscope as the reference deviation and reference step length; Determining whether the relative deviation and the reference deviation are of different signs; When the relative deviation and the reference deviation are of opposite signs, reducing the reference step length according to a preset reduction rule to obtain the adjustment step length; When the relative deviation and the reference deviation have the same sign, the reference step length is determined as the adjustment step length.

5. The method according to claim 2, wherein when the adjustment type is determined to be adjustment of astigmatism, determining the adjustment direction comprises: Performing region division on the first binary image and the second binary image to obtain a positive X region, a negative X region, a positive Y region, and a negative Y region in the first binary image and the second binary image; Analyzing the proportions of foreground pixels in the positive X region, the negative X region, the positive Y region, and the negative Y region to obtain the positive X high frequency proportion, the negative X high frequency proportion, the positive Y high frequency proportion, and the negative Y high frequency proportion of the first binary image and the second binary image; Determine a positive X high frequency difference, a negative X high frequency difference, a positive Y high frequency difference, and a negative Y high frequency difference between the first binary image and the second binary image based on the positive X high frequency ratio, the negative X high frequency ratio, the positive Y high frequency ratio, and the negative Y high frequency ratio; The adjustment direction is determined according to the positive X high frequency difference, the negative X high frequency difference, the positive Y high frequency difference and the negative Y high frequency difference.

6. The method according to claim 5, wherein: Based on the positive X high frequency ratio, the negative X high frequency ratio, the positive Y high frequency ratio, and the negative Y high frequency ratio, determining the positive X high frequency difference, the negative X high frequency difference, the positive Y high frequency difference, and the negative Y high frequency difference between the first binary image and the second binary image includes: Calculating a positive X high frequency difference between a positive X high frequency ratio of the first binary image and a positive X high frequency ratio of the second binary image; Calculating a negative X high frequency difference between a negative X high frequency ratio of the first binary image and a negative X high frequency ratio of the second binary image; Calculating a positive Y high frequency difference between a positive Y high frequency ratio of the first binary image and a positive Y high frequency ratio of the second binary image; A negative Y high frequency difference between a negative Y high frequency ratio of the first binary image and a negative Y high frequency ratio of the second binary image is calculated.

7. The method according to claim 5, wherein: Determining the adjustment direction according to the positive X high frequency difference, the negative X high frequency difference, the positive Y high frequency difference and the negative Y high frequency difference comprises: When the positive X-high frequency difference is greater than 0 and the negative X-high frequency difference is less than 0, determining that the adjustment direction is to increase the X-direction astigmatism value; When the positive X-high frequency difference is less than 0 and the negative X-high frequency difference is greater than 0, determining that the adjustment direction is to reduce the X-direction astigmatism value; When the positive Y high frequency difference is greater than 0 and the negative Y high frequency difference is less than 0, determining that the adjustment direction is to increase the Y direction astigmatism value; When the positive Y high frequency difference is less than 0 and the negative Y high frequency difference is greater than 0, it is determined that the adjustment direction is to reduce the Y-direction astigmatism value.

8. The method according to claim 5, when it is determined that the adjustment type is to adjust astigmatism, determining the adjustment step size comprises: Calculating an X-direction deviation between the positive X high frequency difference and the negative X high frequency difference, and a Y-direction deviation between the positive Y high frequency difference and the negative Y high frequency difference; Determine the X-direction deviation, Y-direction deviation and adjustment step length of the last adjustment of the astigmatism of the scanning electron microscope as the reference X-direction deviation, reference Y-direction deviation and reference step length; The adjustment step is determined according to whether the X-direction deviation and the reference X-direction deviation have different signs, and whether the Y-direction deviation and the reference Y-direction deviation have different signs.

9. The method according to claim 8, wherein: Determining the adjustment step length according to whether the X-direction deviation and the reference X-direction deviation have different signs, and whether the Y-direction deviation and the reference Y-direction deviation have different signs comprises: Determine whether the X-direction deviation and the reference X-direction deviation have different signs, and whether the Y-direction deviation and the reference Y-direction deviation have different signs; When the X-direction deviation has a different sign from the reference X-direction deviation or the Y-direction deviation has a different sign from the reference Y-direction deviation, reducing the reference step length according to a preset reduction rule to obtain the adjustment step length; When the X-direction deviation has the same sign as the reference X-direction deviation and the Y-direction deviation has the same sign as the reference Y-direction deviation, the reference step length is determined as the adjustment step length.

10. The method according to claim 1, wherein: Performing Fourier transform on the first image and the second image to obtain a first frequency domain image and a second frequency domain image includes: Processing the first image and the second image using a Hanning window function to obtain processed first image and second image; Performing Fourier transform on the processed first image and second image to obtain a first frequency domain image and a second frequency domain image.

11. An electronic device, comprising: processor; and a memory storing program instructions for adjusting the scanning electron microscope image, wherein when the program instructions are executed by the processor, the electronic device executes the method according to any one of claims 1-10.

12. A computer-readable storage medium storing program instructions for adjusting a scanning electron microscope image, wherein when the program instructions are executed by a processor, the method according to any one of claims 1 to 10 is implemented.

Images