Image acquisition correction method and device for electron microscope, and program product

Abstract

The embodiment of the invention provides an image acquisition correction method and device for an electron microscope, and a program product. The method comprises the following steps: acquiring acquired images under a plurality of view field sizes through the electron microscope; and for every two adjacent view field sizes, performing resolution adjustment on the first acquisition image with the smaller view field size, and determining a corresponding coordinate of a target pixel point in the image after resolution adjustment in the larger view field size. Based on the standard coordinates and the corresponding coordinates, acquisition deviations are determined. And determining a mapping relation between the view field size and the acquisition deviation according to the acquisition deviation. And carrying out image acquisition deviation correction on the electron microscope based on the mapping relation. According to the technical scheme, pixel size alignment under different view field sizes is achieved through resolution adjustment, the mapping relation between the collection deviation and view field size switching can be accurately constructed based on the collection deviation between every two adjacent view field sizes, and the consistency and accuracy of collected images under different view field sizes are remarkably improved.

Description

Technical Field

[0001] This application belongs to the field of semiconductor testing and measurement technology, and in particular relates to an image acquisition and correction method, device and program product for an electron microscope. Background Technology

[0002] Electron microscopes (EMs) are one of the most important tools for achieving high-precision imaging in the field of semiconductor technology. They are widely used in advanced process monitoring, chip defect detection and yield improvement, and play a key role in ensuring chip quality and reliability.

[0003] Electron microscopes feature magnification switching capabilities, allowing for precise imaging of structures at different scales through flexible adjustment and switching of the field of view. However, in practice, magnification switching with an electron microscope is limited by hardware precision errors and electron beam path deviations, leading to significant acquisition discrepancies in images of the same target area acquired at different magnifications. Consistency between images acquired at different magnifications is difficult to guarantee; for example, the center point of images acquired at different magnifications may not correspond to the same location on the actual wafer. This discrepancy between images acquired at different magnifications severely impacts the accuracy and consistency of the electron microscope image acquisition process, consequently affecting subsequent processing such as defect detection based on the acquired images.

[0004] Therefore, how to effectively eliminate the deviation problem when switching magnification in an electron microscope, thereby improving the image acquisition accuracy, is an important problem that urgently needs to be solved. Summary of the Invention

[0005] This application provides an image acquisition and correction method, device, and program product for an electron microscope, which can correct image acquisition deviations when switching magnification of an electron microscope, thereby improving the consistency and accuracy of acquired images.

[0006] In a first aspect, embodiments of this application provide an image acquisition and correction method for an electron microscope, including: Images of the target region in a wafer are acquired using an electron microscope at multiple field sizes, which are arranged in order of size. For each pair of adjacent field sizes, the resolution of the first acquired image corresponding to the smaller field size is adjusted so that the pixel size of the first acquired image is adjusted to the pixel size of the second acquired image corresponding to the larger field size, thus obtaining the image with the smaller field size after resolution adjustment. Determine the corresponding coordinates of the target pixel in the image after resolution adjustment in the coordinate system of the second acquired image, and determine the acquisition deviation of two adjacent field sizes based on the standard coordinates and corresponding coordinates of the target pixel in the second acquired image. The coordinate system is established with the reference point in the second acquired image as the origin. Based on the acquisition deviation of each pair of adjacent field sizes, determine the mapping relationship between the corresponding field size and the acquisition deviation; Based on the mapping relationship, image acquisition deviation correction is performed on the electron microscope.

[0007] Secondly, embodiments of this application provide an image acquisition and correction device for an electron microscope, comprising: The image acquisition unit is used to acquire images of the target area in the wafer under multiple field sizes using an electron microscope. The multiple field sizes are arranged in order of size. The size adjustment unit is used to adjust the resolution of the first acquired image corresponding to the smaller field of view among every two adjacent field of view sizes, so that the pixel size of the first acquired image is adjusted to the pixel size of the second acquired image corresponding to the larger field of view size, and thus obtains the image after resolution adjustment of the smaller field of view size. The deviation determination unit is used to determine the corresponding coordinates of the target pixel in the image after resolution adjustment in the coordinate system of the second acquired image, and to determine the acquisition deviation of two adjacent field sizes based on the standard coordinates and corresponding coordinates of the target pixel in the second acquired image. The coordinate system is established with the reference point in the second acquired image as the origin. The relationship determination unit is used to determine the mapping relationship between the corresponding field size and the acquisition deviation based on the acquisition deviation of each pair of adjacent field sizes; The deviation correction unit is used to correct image acquisition deviations of the electron microscope based on the mapping relationship.

[0008] Thirdly, embodiments of this application provide an electronic device, which includes a processor, a memory, and a program or instructions stored in the memory and executable on the processor. When the program or instructions are executed by the processor, they implement the steps of the image acquisition and correction method of any of the embodiments of this application for an electron microscope.

[0009] Fourthly, embodiments of this application provide a readable storage medium storing a program or instructions, which, when executed by a processor, implement the steps of an image acquisition and correction method for an electron microscope according to any embodiment of this application.

[0010] Fifthly, embodiments of this application provide a computer program product in which instructions, when executed by a processor of an electronic device, enable the electronic device to perform the steps of any of the image acquisition and correction methods for an electron microscope according to embodiments of this application.

[0011] The technical solutions provided by the embodiments of this application bring at least the following beneficial effects: This application provides an image acquisition and correction method for an electron microscope, comprising: acquiring images of a target region in a wafer at multiple field-of-view sizes using an electron microscope; adjusting the resolution of the first acquired image at the smaller field-of-view size for each pair of adjacent field-of-view sizes, so that the pixel size is adjusted to the pixel size of the larger field-of-view size, thereby obtaining a resolution-adjusted image. Resolution adjustment achieves pixel size alignment at different field-of-view sizes, providing a valid basis for subsequent deviation determination.

[0012] Then, the coordinates of the target pixels in the image after resolution adjustment at the larger field of view are determined, and the acquisition deviation is determined based on the standard coordinates and the corresponding coordinates. Based on the acquisition deviations of every two adjacent field of view sizes, a mapping relationship between the corresponding field of view size and the acquisition deviation is established. When switching the field of view of the electron microscope, the acquisition deviation is corrected based on the mapping relationship. The successful establishment of the mapping relationship provides effective theoretical support for deviation correction during actual field of view switching, thereby ensuring and improving the consistency and accuracy of images acquired under different field of view sizes.

[0013] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is one of the flowcharts illustrating an image acquisition and correction method for an electron microscope according to an embodiment of this application; Figure 2(a) is one of the example schematic diagrams of a mapping relationship provided in an embodiment of this application; Figure 2(b) is a second example of a mapping relationship provided in one embodiment of this application; Figure 3 This is a second schematic flowchart illustrating an image acquisition and correction method for an electron microscope, provided as an embodiment of this application. Figure 4 A schematic diagram of the structure of an image acquisition and correction device for an electron microscope provided in another embodiment of this application; Figure 5 This is a schematic diagram of the hardware structure of an image acquisition and correction device for an electron microscope, provided as an embodiment of this application. Detailed Implementation

[0016] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0017] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0018] The electron microscope (EM) is one of the key instruments in the semiconductor technology field for achieving high-precision imaging. It is widely used in advanced process monitoring, chip defect detection, and yield improvement, playing a vital role in ensuring chip quality and reliability. By flexibly adjusting the field of view, the electron microscope can achieve precise imaging of structures at different scales.

[0019] However, when switching magnification using an electron microscope, the images of the same target area acquired at different magnifications may show significant positional deviations due to factors such as hardware precision errors and electron beam path deviations.

[0020] This deviation issue manifests itself in the fact that the center point of images at different magnifications does not remain consistent on the actual wafer, making it difficult to ensure consistency between images at different magnifications. These defects severely affect the accuracy of electron microscope image acquisition, thus negatively impacting subsequent image-based analysis and processing, such as defect detection.

[0021] To address the aforementioned technical issues, embodiments of this application provide an image acquisition and correction method, device, and program product for an electron microscope. The method includes: acquiring images of a target region in a wafer at multiple field-of-view sizes using an electron microscope. For each pair of adjacent field-of-view sizes, the resolution of the first acquired image at the smaller field-of-view size is adjusted so that the pixel size is adjusted to the pixel size of the larger field-of-view size, resulting in a resolution-adjusted image.

[0022] Then, the coordinates of the target pixels in the image after resolution adjustment at the larger field of view are determined, and the acquisition deviation is determined based on the standard coordinates and the corresponding coordinates. The mapping relationship between the field of view and the acquisition deviation is determined based on the acquisition deviation between every two adjacent field of view sizes. When switching the field of view of the electron microscope, the acquisition deviation is corrected based on the mapping relationship.

[0023] The technical solution provided in this application can achieve pixel size alignment under different field-of-view sizes through resolution adjustment, providing a valid basis for subsequent deviation determination. Based on the acquisition deviation between each adjacent field-of-view size, a precise mapping relationship between acquisition deviation and field-of-view size switching can be constructed. The successful establishment of the mapping relationship provides effective theoretical support for deviation correction during actual field-of-view switching, thereby ensuring and improving the consistency and accuracy between acquired images under different field-of-view sizes.

[0024] The execution entity used in the embodiments of this application can be a terminal device capable of controlling an electron microscope, such as a desktop computer or laptop computer, or a remote device, such as a server. Alternatively, the execution entity used in the embodiments of this application can also be a software entity, such as a client or software program installed on a terminal device. The execution entity for applying the technical solution provided in the embodiments of this application, namely the image acquisition and correction method for an electron microscope, is not strictly limited here; it can be flexibly selected according to the application scenario and actual needs.

[0025] In addition, it should be noted that this application does not strictly limit the specific application scenarios of the image acquisition and correction method for electron microscopes provided in the embodiments of this application, and can be determined according to actual needs.

[0026] For example, in practical scenarios where critical dimensions of important areas on a wafer (such as transistor gates, contact holes, and metal interconnects) are measured using an electron microscope, the image acquisition and correction method for the electron microscope provided in this application can pre-determine the acquisition deviation between adjacent field-of-view sizes based on the images acquired by the electron microscope under different fields of view. Based on the acquisition deviation between each adjacent field of view, a mapping relationship between field-of-view size switching and acquisition deviation can be constructed.

[0027] In this example, when switching the field of view of the electron microscope, the acquisition deviation can be precisely corrected between acquired images based on the established mapping relationship between the field of view size and the acquisition deviation. This allows the electron microscope to acquire accurate and highly consistent images of the same target area, such as the transistor gate, contact hole, and metal interconnect circuit mentioned above, providing real and effective data support for critical dimension measurements.

[0028] It should be noted that the application scenarios described in the above embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided by the embodiments of this application. Those skilled in the art will understand that with the emergence of new application scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems. The image acquisition and correction method for electron microscopes provided in the embodiments of this application can be applied to various application scenarios that require switching the field of view and image acquisition of electron microscopes.

[0029] Figure 1 This is a flowchart illustrating an image acquisition and correction method for an electron microscope, provided as an embodiment of this application.

[0030] like Figure 1 As shown in the figure, the image acquisition and correction method for an electron microscope provided in this application embodiment includes steps S101 to S105.

[0031] S101: Acquire images of the target area in a wafer at multiple field sizes using an electron microscope.

[0032] S102: Adjust the resolution of the first acquired image corresponding to the smaller field of view among every two adjacent field of view sizes, so that the pixel size of the first acquired image is adjusted to the pixel size of the second acquired image corresponding to the larger field of view size, and obtain the image after resolution adjustment of the smaller field of view size.

[0033] S103: Determine the corresponding coordinates of the target pixel in the second acquired image in the coordinate system after resolution adjustment, and determine the acquisition deviation of two adjacent field sizes based on the standard coordinates and corresponding coordinates of the target pixel in the second acquired image.

[0034] S104: Determine the mapping relationship between the corresponding field size and the acquisition deviation based on the acquisition deviation of each pair of adjacent field sizes.

[0035] S105: Based on the mapping relationship, perform image acquisition deviation correction for electron microscopes.

[0036] In step S101, the technical solution provided in this application embodiment can use an electron microscope to sequentially switch multiple field sizes according to a preset field-of-view switching sequence to acquire images of the target area on the wafer under different field sizes. The resolution of the acquired images under each field size is the same, which can all be preset image resolutions, such as 512*512, meaning that one acquired image contains 512 × 512 = 262,144 pixels.

[0037] The target area can be flexibly selected according to the actual pattern distribution on the wafer. In some embodiments, the target area can be a part of the wafer without repeating patterns, or it can be a part of the wafer containing patterns with obvious independent features.

[0038] The above field-of-view switching sequence contains multiple field-of-view sizes arranged sequentially according to their size. Each field-of-view size represents the actual size of the image acquisition area on the wafer when the electron microscope acquires the image. For example, it can be represented by the side length of a square field of view, such as 30 μm (micrometers), 15 μm, etc.

[0039] It should be noted that the embodiments of this application do not strictly limit the specific size of the multiple field-of-view sizes included in the field-of-view switching sequence, nor the specific number of field-of-view sizes. These can be flexibly adjusted according to the application scenario and actual needs of the electron microscope. In some embodiments, the field-of-view switching sequence may include 30μm, 20μm, 10μm, 5μm, 2.5μm, 1μm, etc. In step S101, the field-of-view sizes of the electron microscope can be switched sequentially to acquire images corresponding to field-of-view sizes from 30μm to 1μm, as shown in the example above.

[0040] It should also be noted that, to ensure accurate detection of acquisition deviations between different fields of view, except for the initial field of view size during image acquisition of the target area on the wafer, which requires positioning calibration, subsequent field-of-view size switching does not require further positioning calibration for the target area. This approach ensures that acquisition deviations caused by field-of-view switching are fully reflected in each acquired image, improving the accuracy of determining subsequent acquisition deviations and the mapping relationship between field of view size and acquisition deviation.

[0041] In step S102, the technical solution provided in this application embodiment can adjust the resolution of the acquired image of the smaller field of view among two adjacent field of view sizes, so that the pixel size of the smaller field of view size can be adjusted to the pixel size of the larger field of view size.

[0042] Pixel size represents the actual area size of each pixel on the wafer in the acquired image, which can be expressed as the side length of the actual area. For example, the actual wafer area corresponding to an acquired image with a field of view of 30μm is 30μm * 30μm = 900μm². When the preset image resolution is 512*512, the acquired image contains 262,144 pixels, and the actual area corresponding to each pixel is (30 / 512)² = (0.05859375)² = 0.003433227539062μm², so the pixel size can be 0.05859375μm.

[0043] In the embodiments provided in this application, for each pair of adjacent field-of-view sizes in the above-mentioned field-of-view switching sequence, the image with the smaller field-of-view size can be used as the first image whose resolution needs to be adjusted, and the image with the larger field-of-view size can be used as the second image. Based on the preset image resolution and the larger field-of-view size among the adjacent field-of-view sizes, the pixel size of the second image is calculated.

[0044] For example, in the above example, for the 30μm and 20μm in the field of view switching sequence, the acquired image with a field of view size of 20μm is used as the first acquired image, and the acquired image with a field of view size of 30μm is used as the second acquired image. When the preset image resolution is 512*512, the pixel size is 0.05859375μm.

[0045] Then, based on the pixel size of the second acquired image, the first acquired image with a smaller field of view can be re-segmented into pixels, so that the pixel size of the first acquired image can be enlarged to the pixel size of the second acquired image, thereby obtaining the first acquired image with adjusted resolution.

[0046] For example, based on the above example, the first acquired image with a field of view of 20 μm has a pixel size of 0.0390625 μm at a resolution of 512*512. The first acquired image is then re-segmented into pixels, increasing the pixel size from 0.0390625 μm to 0.05859375 μm with a field of view of 30 μm.

[0047] After resolution adjustment, the actual wafer area corresponding to the entire first acquired image remains unchanged, but the increase in pixel size leads to a decrease in the number of pixels, resulting in a decrease in the corresponding resolution. In the example above, the resolution of the first acquired image will decrease from 512*512 to approximately 341*341. Other adjacent field-of-view sizes in the field-of-view switching sequence of the above example can also undergo the above processing, for example, 20μm and 10μm, 10μm and 5μm, 5μm and 2.5μm, 2.5μm and 1μm, to determine the resolution-adjusted image corresponding to the smaller field-of-view size.

[0048] Based on the above embodiments, pixel-level spatial alignment can be achieved under different field-of-view sizes, laying a practical theoretical foundation for subsequent coordinate mapping and determination of acquisition deviations. This embodiment enables the detection of subsequent acquisition deviations, thereby accurately establishing the mapping relationship between field-of-view size and acquisition deviation, providing effective assistance for deviation correction during actual field-of-view switching.

[0049] In step S103, for every two adjacent field-of-view sizes, the technical solution provided in this application embodiment can determine the corresponding coordinates of the target pixel in the resolution-adjusted image of the smaller field-of-view size in the coordinate system of the second acquired image of the larger field-of-view size.

[0050] Furthermore, based on the corresponding coordinates of the target pixel and its standard coordinates in the second acquired image when there is no acquisition deviation, the acquisition deviation caused by field switching between every two adjacent field sizes can be accurately determined.

[0051] The coordinate system of the second acquired image can be a two-dimensional Cartesian coordinate system established with a preset reference point in the second acquired image as the origin. The preset reference point is not strictly limited and can be the lower left corner, center point, etc., of the acquired image. The corresponding coordinates of the target pixel represent the coordinates of the pixel in the second acquired image that has the same content as the target pixel in the resolution-adjusted image after the pixel size adjustment steps described above. The standard coordinates represent the coordinates of the position of the target pixel in the resolution-adjusted image in the second acquired image, under the condition that there is no acquisition deviation during field of view switching.

[0052] The specific location of the target pixel in the resolution-adjusted image is not strictly limited in this application; the pixel corresponding to the center point of the resolution-adjusted image can be used as the target pixel. Ideally, without the influence of acquisition bias, the actual image content corresponding to the center point of images acquired from different fields of view should be completely consistent.

[0053] However, due to acquisition bias during field-of-view switching, the center point of the acquired images with different field-of-view sizes is no longer the same on the actual wafer, exhibiting a certain degree of offset, i.e., acquisition bias. By observing the positional changes of the same pixel in different acquired images, the acquisition bias during field-of-view switching can be accurately determined.

[0054] Specifically, in the embodiments provided in this application, for every two adjacent field-of-view sizes, the target pixel in the image can be adjusted based on the resolution of the smaller field-of-view size. Pixel matching is then performed on the second acquired image with the larger field-of-view size to determine the corresponding pixel in the second acquired image that is identical to the target pixel. The coordinates of the corresponding pixel in the coordinate system of the second acquired image can be used as the corresponding coordinates of the target pixel.

[0055] Then, the coordinate difference can be determined based on the standard coordinates of the target pixel and the corresponding coordinates obtained by matching, which serves as the acquisition deviation between two adjacent field-of-view sizes.

[0056] The process of determining acquisition deviation is illustrated using the above example. After adjusting the resolution of the acquired images with a field of view of 30μm and 20μm, i.e., adjusting the first acquired image with a field of view of 20μm from 512*512 to 341*341, the center pixel of the resolution-adjusted image with a field of view of 20μm can be selected as the target pixel. That is, with the lower left corner of the resolution-adjusted image as the origin, the direction from the lower left corner to the upper left corner as the positive vertical axis, and the direction from the lower left corner to the lower right corner as the positive horizontal axis, a two-dimensional Cartesian coordinate system is established, and the pixel with coordinates (171, 171) is selected as the target pixel. In this case, the standard coordinates corresponding to the target pixel should be the coordinates corresponding to the center point of the second acquired image.

[0057] Then, from the 512*512 pixels contained in the second acquired image with a field of view of 30μm, the corresponding pixel that matches the target pixel in the resolution-adjusted image can be determined. The specific matching method is not strictly limited in this embodiment. In some embodiments, precise pixel matching can be achieved through template matching, feature-based matching, or phase correlation algorithms, etc., which can be flexibly selected according to actual needs and application scenarios.

[0058] Assume that the coordinate system of the second acquired image is a two-dimensional Cartesian coordinate system with the lower left corner as the origin. In this example, the coordinates of the target pixel in the second acquired image are determined to be (251, 255) in the coordinate system, which are then used as the coordinates of the target pixel. The standard coordinates of the target pixel are the coordinates of the center point of the second acquired image, which are approximately (256, 256) in the coordinate system.

[0059] In this example, the acquisition deviation between the field of view sizes of 30μm and 20μm can be determined based on the corresponding coordinates (251, 255) of the target pixel and the standard coordinates (256, 256). The coordinate difference includes the horizontal acquisition deviation Δx = 256 - 251 = 5 and the vertical acquisition deviation Δy = 256 - 255 = 1. Similar to the example above, corresponding processing and calculations can be performed for other adjacent field of view sizes (e.g., 20μm and 10μm, 10μm and 5μm, etc.) in the field of view switching sequence to obtain the acquisition deviation at each field of view size switch.

[0060] Based on the above embodiments, pixel-level detection of acquisition deviations caused by field-of-view switching in electron microscopes can be achieved, significantly improving the detection accuracy of acquisition deviations. Furthermore, the determination process is applicable to various resolutions and field-of-view sizes, demonstrating strong applicability and flexibility. This embodiment can provide sufficient data support for constructing the mapping relationship between subsequent field-of-view sizes and acquisition deviations, effectively achieving deviation correction during field-of-view switching in practical applications.

[0061] Regarding the specific process of determining the corresponding pixel of the aforementioned target pixel in the second acquired image, in the embodiments provided in this application, the corresponding pixel can be accurately matched by a template matching algorithm.

[0062] Specifically, firstly, a pixel template region containing the target pixels can be determined from the resolution-adjusted image based on a preset pixel template size. The preset pixel template size represents the area of ​​the pixel template region on the resolution-adjusted image, and its specific size can be flexibly set based on the actual field of view and image resolution.

[0063] The specific location of the target pixel in the pixel template area is not limited in the embodiments of this application. In some embodiments, the pixel template area may be determined with the target pixel as the center point, or the target pixel may be selected at other locations, which can be flexibly chosen.

[0064] Then, the divided pixel template regions can be matched on the second acquired image in units of pixels to determine the similarity between each region of the same size in the second acquired image and the pixel template region.

[0065] The sliding region with the highest similarity is selected as the region to match the pixel template region. The coordinates of the reference points in the determined sliding region in the second acquired image can be used as the template coordinates of the pixel template region in the second acquired image. Based on the template coordinates and the position of the target pixel in the pixel template region, the corresponding pixel and its coordinates can be determined.

[0066] Based on the above embodiments, the target pixel of the image after resolution adjustment can be accurately determined in the second acquired image. The matching accuracy of the pixel is guaranteed by the template region matching method. Compared with the feature matching of a single pixel, the matching calculation is greatly reduced and the matching efficiency of the corresponding pixel is significantly improved. This also improves the efficiency of determining the acquisition deviation and the subsequent mapping relationship between the field of view size and the acquisition deviation.

[0067] In step S104, the technical solution provided by this application can construct a mapping relationship between the field size and the acquisition deviation corresponding to each two adjacent field size switching based on the acquisition deviation, so that accurate deviation correction can be achieved when actually switching fields.

[0068] The aforementioned mapping relationship represents the acquisition deviation that needs to be adjusted when switching between different field sizes in a field-of-view switching sequence. Specifically, it can be used in practical applications to correct acquisition deviations when switching fields of view in an electron microscope. The specific form of the mapping relationship between field size and acquisition deviation is not strictly limited in the embodiments of this application. In some embodiments, it can be represented by a relational function or a data table, and can be flexibly selected according to actual needs and application scenarios.

[0069] In one embodiment provided in this application, the acquisition deviation between every two adjacent field sizes in the field switching sequence can be linearly fitted with the field switching sequence to obtain a functional relationship representing the field size switching and acquisition deviation, which serves as the aforementioned mapping relationship.

[0070] Specifically, as in the example above, the acquisition deviation between any two adjacent field-of-view sizes can include a horizontal axis coordinate deviation in the horizontal direction and a vertical axis coordinate deviation in the vertical direction. Based on this, in some embodiments, the mapping relationship can also be divided into a first mapping relationship between the field-of-view size and the horizontal axis coordinate deviation, and a second mapping relationship between the field-of-view size and the vertical axis coordinate deviation.

[0071] The first mapping relationship described above can be determined by linearly fitting the horizontal acquisition deviation of each pair of adjacent field-of-view sizes to the field-of-view switching sequence. Similarly, the second mapping relationship described above can be determined by linearly fitting the vertical acquisition deviation of each pair of adjacent field-of-view sizes to the field-of-view switching sequence.

[0072] Taking the field-of-view switching sequence containing 30μm, 20μm, 10μm, 5μm, 2.5μm, and 1μm in the above example as an example, the process of determining the mapping relationship in the above embodiment is illustrated. The acquisition deviations corresponding to the field-of-view switching sequence in this example can be referred to Table 1. The first and second mapping relationships constructed based on Table 1 can be referred to the examples shown in Figures 2(a) and 2(b).

[0073]

[0074] Table 1. Horizontal and vertical axis coordinate deviations corresponding to the field-of-view switching sequence. Figures 2(a) and 2(b) are schematic diagrams illustrating an example of a mapping relationship provided in one embodiment of this application.

[0075] Figure 2(a) is a function curve of the first mapping relationship between the field of view size and the deviation of the horizontal axis coordinate in the mapping relationship. Based on the horizontal axis coordinate deviation data in the example shown in Table 1, the function curve shown in Figure 2(a) can be fitted, and the corresponding function expression can be the following formula (1): Formula (1) in, The vertical axis is shown in Figure 2(a), and the horizontal axis coordinate deviation is represented. This refers to the field of view size after the field of view is switched, for example, when switching from 30μm to 20μm. The value is 20 μm, and other size switching follows the same principle. Based on formula (1), the lateral acquisition deviation of the electron microscope can be accurately determined when actually switching the field of view size, so as to perform effective deviation correction in the lateral direction, improve the acquisition accuracy of the acquired image and the consistency between the acquired image and the acquired image under other fields of view.

[0076] Figure 2(b) is a function curve of the second mapping relationship between the field of view size and the deviation of the vertical axis coordinate in the mapping relationship. Based on the vertical axis coordinate deviation data in the example shown in Table 1, the function curve shown in Figure 2(b) can be fitted, and the corresponding function expression can be the following formula (1): Formula (2) in, The vertical axis shown in Figure 2(b) represents the vertical axis coordinate deviation. This refers to the field of view size after the field of view is switched, for example, when switching from 30μm to 20μm. The value is 20 μm, and other size switching follows the same principle. Based on formula (2), the longitudinal acquisition deviation of the electron microscope can be accurately determined when actually switching the field of view size, so as to perform effective deviation correction in the longitudinal direction, improve the acquisition accuracy of the acquired image and the consistency between the acquired image and the acquired image under other fields of view.

[0077] The above embodiments enable the precise construction of a mapping relationship between field-of-view size switching and acquisition deviation based on the acquisition deviation between adjacent field-of-view sizes. This accurate determination of the mapping relationship effectively assists in deviation correction during subsequent actual field-of-view switching in electron microscopy, enabling effective deviation prediction and compensation for arbitrary field-of-view size switching and significantly improving the acquisition accuracy of the acquired images.

[0078] In step S105, the technical solution provided in this application embodiment can accurately correct the image acquisition deviation caused by the field of view switching based on the mapping relationship constructed in the above steps when the field of view of the electron microscope is actually switched.

[0079] Specifically, in the embodiments provided in this application, the acquisition deviation to be corrected when switching from the initial field of view to the target field of view can be determined from the above mapping relationship based on the initial field of view size of the electron microscope before field of view switching and the target field of view size to which the field of view needs to be switched.

[0080] Then, based on the acquisition deviation to be corrected, the electron microscope is subjected to image acquisition deviation correction, so that the center point of the acquired image under the initial field of view and the target field of view can be accurately aligned, ensuring the consistency between acquired images under different field of view sizes.

[0081] For example, based on the field-of-view switching sequence in the above example, when switching from a field-of-view size of 30μm to a field-of-view size of 20μm in actual use of an electron microscope, the horizontal axis coordinate deviation and vertical axis coordinate deviation when switching from a field-of-view size of 30μm to 20μm can be determined based on the mapping relationship shown in Formula (1) and Figure 2(a), and Formula (2) and Figure 2(b), and used as the acquisition deviation to be corrected.

[0082] This application does not strictly limit the specific method for correcting acquisition deviation using an electron microscope. In some embodiments, the image acquisition deviation caused by field-of-view switching can be compensated for and eliminated by adjusting the coil current of the electron microscope based on the acquisition deviation to be corrected. Specifically, the deflection coil current of the electron microscope can be adjusted. After determining the acquisition deviation to be corrected after field-of-view switching, the current applied to the deflection coil can be changed to fine-tune the landing position of the electron beam, so that the acquisition deviation can be successfully corrected.

[0083] In other embodiments, other methods of correcting acquisition deviations may also be used. For example, in some embodiments, the position of the image acquisition target (e.g., a wafer) may be adjusted based on the acquisition deviation to be corrected, or the acquired image may be corrected for deviation using software algorithms after acquisition. The appropriate method can be flexibly selected according to actual needs and application scenarios.

[0084] Based on the above embodiments, acquisition deviations caused by field-of-view switching can be accurately corrected in practical applications of electron microscopy, ensuring the consistency of images acquired under different field-of-view sizes. This embodiment enables highly automated deviation correction, eliminating the need for manual target correction after field-of-view switching, significantly improving the accuracy of acquired images while also greatly enhancing acquisition efficiency.

[0085] The above are several feasible embodiments of the technical solutions provided in this application. To facilitate understanding of the combined effects of the above embodiments, a comprehensive overview of the overall process architecture of the image acquisition and correction method for an electron microscope is provided below. For details, please refer to... Figure 3 As shown in the image.

[0086] Figure 3 This is a schematic flowchart illustrating an image acquisition and correction method for an electron microscope, provided as an embodiment of this application. Figure 3 As shown, it includes steps S301 to S305.

[0087] S301: Acquire images of each field of view size in a field-of-view switching sequence at the same resolution using an electron microscope.

[0088] S302: For each pair of adjacent field-of-view images, adjust the pixel size of the smaller field-of-view image to the pixel size of the larger field-of-view image to obtain an image with adjusted resolution.

[0089] S303: Determine the coordinates of the target pixel in the image after resolution adjustment in the acquired image with a larger field of view, and determine the acquisition deviation between two adjacent field of view sizes based on the standard coordinates and corresponding coordinates of the target pixel.

[0090] S304: Based on the acquisition deviation between every two adjacent field of view sizes, fit the functional relationship between field of view size switching and acquisition deviation, and construct the mapping relationship between field of view size and acquisition deviation.

[0091] S305: When the electron microscope performs actual field of view switching, it determines the acquisition deviation to be corrected when switching from the initial field of view size to the target field of view size based on the mapping relationship, and adjusts the coil current of the electron microscope based on the acquisition deviation to be corrected to achieve image acquisition deviation correction.

[0092] Through steps S301 to S305, an accurate mapping relationship between the field of view size and acquisition deviation can be established for electron microscopes. Based on this mapping relationship, the acquisition deviation can be precisely corrected during actual field of view switching, improving the accuracy of acquired images and the consistency between acquired images at different field of view sizes. The specific details of each step can be found in the above embodiments, and will not be elaborated further here.

[0093] The above describes the specific implementation of the image acquisition and correction method for an electron microscope provided in this application. The technical solution provided in this application can achieve pixel size alignment under different field-of-view sizes through resolution adjustment, laying the foundation for subsequent deviation determination. Based on the acquisition deviation between every two adjacent field-of-view sizes, a precise mapping relationship between field-of-view size switching and acquisition deviation can be constructed. This precisely constructed mapping relationship can be directly used to guide dynamic deviation compensation of the electron microscope during field-of-view switching, ensuring that acquired images under different field-of-view sizes are strictly aligned in physical space, significantly improving the consistency and accuracy of acquired images.

[0094] Based on the image acquisition and correction method for an electron microscope provided in the above embodiments, this application also provides specific implementation methods of an image acquisition and correction device for an electron microscope, as shown in the following embodiments.

[0095] Figure 4 A schematic diagram of an image acquisition and correction device for an electron microscope provided in another embodiment of this application. The image acquisition and correction device 400 for an electron microscope includes: Image acquisition unit 401 is used to acquire images of a target area in a wafer under multiple field sizes using an electron microscope, with the multiple field sizes arranged in order of size. The size adjustment unit 402 is used to adjust the resolution of the first acquired image corresponding to the smaller field of view among every two adjacent field of view sizes, so that the pixel size of the first acquired image is adjusted to the pixel size of the second acquired image corresponding to the larger field of view size, and thus obtains the image after resolution adjustment of the smaller field of view size. The deviation determination unit 403 is used to determine the corresponding coordinates of the target pixel in the image after resolution adjustment in the coordinate system of the second acquired image, and to determine the acquisition deviation of two adjacent field sizes based on the standard coordinates and corresponding coordinates of the target pixel in the second acquired image. The coordinate system is established with the reference point in the second acquired image as the origin. The relationship determination unit 404 is used to determine the corresponding field size and acquisition deviation mapping relationship based on the acquisition deviation of each pair of adjacent field sizes; Deviation correction unit 405 is used to correct image acquisition deviations of the electron microscope based on mapping relationships.

[0096] In some embodiments, the size adjustment unit 402 described above is specifically used for: For each pair of adjacent field-of-view sizes, the pixel size of the second acquired image is determined based on the larger field-of-view size; Based on the pixel size of the second acquired image, the first acquired image is segmented into pixels, so that the pixel size of the first acquired image is re-segmented into the pixel size of the second acquired image, resulting in an image with adjusted resolution.

[0097] In some embodiments, the deviation determination unit 403 is specifically used for: Based on the target pixel in the image after resolution adjustment, the corresponding pixel matching the target pixel is determined from the second acquired image, and the coordinates of the corresponding pixel in the coordinate system are used as the corresponding coordinates of the target pixel. The coordinate difference between the standard coordinate and the corresponding coordinate is determined as the acquisition deviation between two adjacent field sizes. The standard coordinate represents the coordinate of the target pixel in the coordinate system when there is no acquisition deviation between two adjacent field sizes.

[0098] In some embodiments, the deviation determination unit 403 is specifically used for: Based on the resolution-adjusted image and the preset pixel template size, determine the pixel template region containing the target pixels; For the pixel template region, sliding matching is performed on the second acquired image in units of pixels to determine the image region in the second acquired image that has the highest similarity to the pixel template region. The coordinates of the reference points in a portion of the image region in the coordinate system are used as the corresponding coordinates of the pixel template region in the coordinate system. Based on the corresponding coordinates of the template, the corresponding pixel of the target pixel in the second acquired image is determined.

[0099] In some embodiments, the relationship determination unit 404 is specifically used for: Linear fitting is performed on the acquisition deviation of all adjacent field-of-view sizes to determine the functional relationship between the acquisition deviation and the field-of-view size, which serves as the mapping relationship.

[0100] In some embodiments, the acquisition bias includes horizontal axis coordinate bias and vertical axis coordinate bias, and the mapping relationship includes a first mapping relationship between the field of view size and the horizontal axis coordinate bias and a second mapping relationship between the field of view size and the vertical axis coordinate bias; The aforementioned relationship determination unit 404 is specifically used for: Linear fitting is performed on the transverse acquisition deviation of all adjacent field-of-view sizes to determine the functional relationship between the transverse acquisition deviation and the field-of-view size, which serves as the first mapping relationship. Linear fitting is performed on the longitudinal acquisition deviation of all adjacent field-of-view sizes to determine the functional relationship between the longitudinal acquisition deviation and the field-of-view size, which serves as the second mapping relationship.

[0101] In some embodiments, the deviation correction unit 405 is specifically used for: Based on the initial field-of-view size and the target field-of-view size of the electron microscope, the acquisition deviation to be corrected that needs to be adjusted for field-of-view switching of the electron microscope is determined from the mapping relationship. Based on the acquisition deviation to be corrected, the electron microscope is used to correct the image acquisition deviation.

[0102] In some embodiments, the deviation correction unit 405 is specifically used for: Based on the acquisition bias to be corrected, the coil current of the electron microscope is adjusted to eliminate the acquisition bias to be corrected when switching the electron microscope from the initial field of view to the target field of view.

[0103] Figure 5 This is a schematic diagram of the hardware structure of an image acquisition and correction device for an electron microscope, provided as an embodiment of this application.

[0104] The image acquisition and correction device of an electron microscope may include a processor 501 and a memory 502 storing computer program instructions.

[0105] Specifically, the processor 501 may include a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0106] Memory 502 may include mass storage for data or instructions. For example, and not limitingly, memory 502 may include a hard disk drive (HDD), floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or Universal Serial Bus (USB) drive, or a combination of two or more of these. Where appropriate, memory 502 may include removable or non-removable (or fixed) media. Where appropriate, memory 502 may be internal or external to the integrated gateway disaster recovery device. In a particular embodiment, memory 502 is non-volatile solid-state memory.

[0107] In a particular embodiment, memory 502 includes read-only memory (ROM). Where appropriate, the ROM may be a mask-programmed ROM, a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), an electrically rewritable ROM (EAROM), or flash memory, or a combination of two or more of these.

[0108] The processor 501 reads and executes computer program instructions stored in the memory 502 to implement any of the image acquisition and correction methods for electron microscopes in the above embodiments.

[0109] In one example, the image acquisition and correction device for an electron microscope may also include a communication interface 503 and a bus 510. Wherein, as Figure 5 As shown, the processor 501, memory 502, and communication interface 503 are connected through bus 510 and complete communication with each other.

[0110] The communication interface 503 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0111] Bus 510 includes hardware, software, or both, that couples components of an online data traffic metering device together. For example, and not limitingly, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), HyperTransport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Low Pin Count (LPC) bus, a memory bus, a Microchannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses, or combinations of two or more of these. Where appropriate, bus 510 may include one or more buses. Although specific buses are described and illustrated in embodiments of this application, this application contemplates any suitable bus or interconnect.

[0112] Furthermore, in conjunction with the image acquisition and correction methods for electron microscopes described in the above embodiments, this application embodiment can provide a computer storage medium for implementation. This computer storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any of the image acquisition and correction methods for electron microscopes described in the above embodiments.

[0113] This application also provides a computer program product, including a computer program that, when executed, implements any of the image acquisition and correction methods for electron microscopes described in the above embodiments.

[0114] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0115] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0116] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0117] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0118] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. An image acquisition and correction method for an electron microscope, characterized in that, include: Images of a target region in a wafer are acquired using an electron microscope at multiple field-of-view sizes, which are arranged in order of size. The resolution of the first acquired image corresponding to the smaller field of view among every two adjacent field of view sizes is adjusted so that the pixel size of the first acquired image is adjusted to the pixel size of the second acquired image corresponding to the larger field of view size, thus obtaining the resolution-adjusted image of the smaller field of view size. The corresponding coordinates of the target pixel in the image after resolution adjustment in the coordinate system of the second acquired image are determined, and the acquisition deviation of the two adjacent field sizes is determined based on the standard coordinates of the target pixel in the second acquired image and the corresponding coordinates. The coordinate system is established with the reference point in the second acquired image as the origin. Based on the acquisition deviation of each pair of adjacent field sizes, determine the mapping relationship between the corresponding field size and the acquisition deviation; Based on the mapping relationship, the electron microscope is subjected to image acquisition deviation correction.

2. The method according to claim 1, characterized in that, For each pair of adjacent field-of-view sizes, the resolution of the first acquired image corresponding to the smaller field-of-view size is adjusted so that the pixel size of the first acquired image is adjusted to the pixel size of the second acquired image corresponding to the larger field-of-view size, resulting in a resolution-adjusted image of the smaller field-of-view size, including: For each pair of adjacent field-of-view sizes, the pixel size of the second acquired image is determined based on the larger field-of-view size; Based on the pixel size of the second acquired image, the first acquired image is segmented into pixels, so that the pixel size of the first acquired image is re-segmented into the pixel size of the second acquired image, thus obtaining the resolution-adjusted image.

3. The method according to claim 1, characterized in that, Determine the corresponding coordinates of the target pixel in the resolution-adjusted image within the coordinate system of the second acquired image, and based on the standard coordinates of the target pixel in the second acquired image and the corresponding coordinates, determine the acquisition deviation between two adjacent field-of-view sizes, including: Based on the target pixel in the resolution-adjusted image, a corresponding pixel matching the target pixel is determined from the second acquired image, and the coordinates of the corresponding pixel in the coordinate system are used as the corresponding coordinates of the target pixel. The coordinate difference between the standard coordinate and the corresponding coordinate is determined as the acquisition deviation between the two adjacent field sizes. The standard coordinate represents the coordinate of the target pixel in the coordinate system when there is no acquisition deviation between the two adjacent field sizes.

4. The method according to claim 3, characterized in that, Based on the target pixel in the resolution-adjusted image, matching the corresponding pixel that is the same as the target pixel from the second acquired image includes: Based on the resolution-adjusted image and the preset pixel template size, a pixel template region containing the target pixel is determined. For the pixel template region, a sliding matching is performed on the second acquired image in units of pixels to determine the image region in the second acquired image that has the highest similarity to the pixel template region; The coordinates of the region reference point in the partial image region in the coordinate system are used as the template coordinates of the pixel template region in the coordinate system, and the corresponding pixel point of the target pixel point in the second acquired image is determined based on the template coordinates.

5. The method according to claim 1, characterized in that, Based on the acquisition deviation of each pair of adjacent field-of-view sizes, the mapping relationship between the corresponding field-of-view size and the acquisition deviation is determined, including: Linear fitting is performed on the acquisition deviation of all adjacent two field-of-view sizes to determine the functional relationship between the acquisition deviation and the field-of-view size, which is used as the mapping relationship.

6. The method according to claim 5, characterized in that, The acquisition deviation includes the horizontal axis coordinate deviation and the vertical axis coordinate deviation, and the mapping relationship includes a first mapping relationship between the field of view size and the horizontal axis coordinate deviation and a second mapping relationship between the field of view size and the vertical axis coordinate deviation; A linear fit is performed on the acquisition deviations of all adjacent field-of-view sizes to determine the functional relationship between the acquisition deviation and the field-of-view size, which serves as the mapping relationship, including: Linear fitting is performed on the transverse acquisition deviations of all adjacent field-of-view sizes to determine the functional relationship between the transverse acquisition deviations and the field-of-view sizes, which serves as the first mapping relationship. Linear fitting is performed on the longitudinal acquisition deviation of all two adjacent field-of-view sizes to determine the functional relationship between the longitudinal acquisition deviation and the field-of-view size, which is used as the second mapping relationship.

7. The method according to claim 1, characterized in that, Based on the mapping relationship, image acquisition deviation correction is performed on the electron microscope, including: Based on the initial field-of-view size and the target field-of-view size of the electron microscope, the acquisition deviation to be corrected that needs to be adjusted for field-of-view switching of the electron microscope is determined from the mapping relationship; Based on the acquisition deviation to be corrected, the electron microscope is subjected to image acquisition deviation correction.

8. The method according to claim 7, characterized in that, Based on the acquisition deviation to be corrected, the electron microscope is subjected to image acquisition deviation correction, including: Based on the acquisition deviation to be corrected, the coil current of the electron microscope is adjusted to eliminate the acquisition deviation to be corrected when the electron microscope is switched from the initial field of view to the target field of view.

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

10. A computer program product, characterized in that, When the instructions in the computer program product are executed by the processor of the electronic device, the electronic device causes the electronic device to perform the image acquisition and correction method for an electron microscope as described in any one of claims 1-8.

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