Calibration method of electron beam measuring equipment, medium, product and equipment

Abstract

The invention provides a calibration method of electron beam measuring equipment, a medium, a product and equipment. The method comprises the following steps: acquiring a calibration formula; determining an image acquisition position of the electron microscope scanning image according to the calibration formula; generating an electron microscope scanning image at the image acquisition position of the detection wafer through electron beam measurement equipment; determining a plurality of to-be-measured feature patterns in the electron microscope scanning image according to the calibration formula, and carrying out critical dimension measurement on the to-be-measured feature patterns to obtain coordinate information corresponding to each to-be-measured feature pattern; fitting the coordinate information to obtain a straight line of the to-be-measured feature graph along the coordinate axis direction; and determining the angular deviation of the electron beam measuring equipment according to the straight line, and compensating the angular deviation into the electron beam measuring equipment. Through the method, high automation of an electron beam measuring equipment calibration scheme can be realized, result fluctuation caused by operation difference of personnel is thoroughly eliminated, high consistency and repeatability of calibration operation are ensured, and calibration efficiency is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor technology, in particular to a calibration method of an electron beam measurement device, a medium, a product and a device. BACKGROUND

[0002] As a key device for nanoscale surface topography analysis, Scanning Electron Microscope (SEM) plays an irreplaceable role in the fields of semiconductor manufacturing, material science and life science. In particular, in integrated circuit manufacturing, Critical Dimension SEM (CD-SEM) has become the core metrology tool for process control, which realizes real-time monitoring and feedback for key process links such as lithography and etching by imaging and measuring nanoscale pattern structures on wafer surface. With the continuous shrinking of semiconductor technology nodes to 5 nanometers and below, the measurement accuracy, stability and throughput of CD-SEM are almost extremely demanding. Under this background, the performance stability of electron optical system has become one of the key factors affecting the reliability of measurement results. Among them, the orthogonality between the electron beam and the sample plane is an important indicator to ensure the geometric accuracy of the image. If the orthogonality deviation is caused by scanning coil assembly error, magnetic field asymmetry or electron optical distortion, etc., it will cause the collected image to appear tilt, stretch and other geometric distortion, and then introduce non-negligible measurement error, which seriously affects the judgment and control of the process window.

[0003] At present, the calibration of the orthogonality of the electron beam device in the industry still relies more on manual operation, that is, the technical personnel manually adjusts the system parameters according to the observed image features based on experience. Although this method can realize basic calibration, it has several inherent limitations: first, the calibration accuracy is greatly affected by the subjective experience of personnel, and it is difficult to achieve sub-pixel level accurate alignment; second, the calibration efficiency is low, and it cannot meet the high throughput requirements of the equipment in the mass production environment; third, it lacks consistency and repeatability, and the calibration results of different personnel or different time points may be different. In response to the above challenges, in recent years, some technical solutions have tried to introduce automation means, for example, by extracting feature structures through traditional image processing algorithms (such as binarization, contour extraction), and then calculating the image tilt angle based on the feature points and compensating. However, this method still has shortcomings in feature extraction accuracy, robustness to image quality, and closed-loop verification of the calibration process, and it is difficult to provide stable and reliable orthogonality guarantee in high-end manufacturing scenarios. Therefore, how to realize an automatic orthogonality calibration method with high precision, high efficiency and high consistency without relying on manual intervention has become a key problem to be solved in the field of electron beam measurement technology. SUMMARY

[0004] In view of the above problems, the present invention proposes a calibration method, medium, product and equipment for an electron beam measurement device that overcomes or at least partially solves the above problems.

[0005] One objective of this invention is to achieve full-process standardization and automated calibration of electron beam measurement equipment; Another further objective of this invention is to improve the calibration accuracy of electron beam measurement equipment.

[0006] Specifically, the present invention provides a calibration method for an electron beam measurement device, comprising: Obtain the calibration recipe, which records the reference information of the target calibration area on the detection wafer, and detect the array arrangement feature area on the detection wafer; Determine the image acquisition location for electron microscope scanning images based on the calibration formula; Electron microscopy images are generated at the image acquisition locations of the inspected wafer using electron beam metrology equipment; Based on the calibration formula, multiple feature patterns to be measured are identified in the electron microscope scanning image, and the key dimensions of the feature patterns to be measured are measured to obtain the coordinate information corresponding to each feature pattern to be measured. Straight lines along the coordinate axes of the feature image to be measured are obtained by fitting coordinate information; The angular deviation of the electron beam measurement equipment is determined based on the straight line, and the angular deviation is compensated for in the electron beam measurement equipment.

[0007] Optionally, the calibration recipe includes a registered image of the target calibration area and the location of the measurement frame in the registered image; The steps for determining multiple target feature patterns in electron microscopy scan images based on calibration formulas include: Calculate the offset between the registered image and the electron microscope scan image; The position of the measurement frame in the electron microscope scan image is determined based on the offset and the position of the measurement frame. Multiple feature patterns to be measured are determined in the electron microscope scanning image based on the measurement frame.

[0008] Optionally, the calibration formula includes measurement parameters; The steps for determining multiple feature patterns to be measured in an electron microscopy scan image based on a measurement frame include: Obtain the array arrangement of the feature image to be measured from the measurement parameters; The measurement frames are arranged in an array to select multiple feature images to be measured.

[0009] Optionally, the steps for determining the angular deviation of the electron beam measurement equipment based on a straight line include: Based on the coordinate axis direction, the straight line is divided into two types of straight lines with different coordinate axis directions, and the included angle between the two types of straight lines is calculated. Determine whether the angular deviation between the included angle and the right angle is less than a preset threshold; If the angle deviation is greater than a preset threshold, the step of compensating the angle deviation into the electron beam measurement device is executed.

[0010] Optionally, after the step of compensating for the angular deviation in the electron beam measurement device, the method further includes: The compensated electron beam measurement equipment is used to repeatedly perform the step of generating an electron microscope scanning image at the image acquisition position of the wafer through the electron beam measurement equipment for iterative calibration until the calculated angle deviation is less than the preset threshold. If the angle deviation is still greater than the preset threshold when the number of iterations reaches the preset maximum number of iterations, the calibration operation will be terminated and a prompt message will be generated.

[0011] Optionally, the coordinate information includes the centroid coordinates; The steps for measuring the key dimensions of the feature graphic to be measured and obtaining the coordinate information corresponding to each feature graphic include: Edge points are labeled on the feature graphics to be tested to obtain the edge points corresponding to each feature graphics to be tested; The centroid coordinates of each feature image to be tested are calculated based on the edge points of each feature image to be tested.

[0012] Optionally, the calibration recipe includes the wafer coordinates of the target calibration region; The steps of generating electron microscopy images at the image acquisition locations of inspected wafers using electron beam metrology equipment include: Wafer coordinates are obtained by calibrating the formula; The sample stage of the electron beam metrology equipment is moved to the position corresponding to the wafer coordinates, so that the image acquisition position is within the electron beam scanning range; The electron beam measurement device is controlled to scan the image acquisition position, thereby obtaining the electron microscope scan image.

[0013] According to another aspect of the present invention, a computer-readable storage medium is also provided, on which a computer program is stored, wherein the computer program, when executed by a processor, implements the steps of the calibration method of any of the above-described electron beam measurement devices.

[0014] According to another aspect of the present invention, a computer program product is also provided, comprising a computer program that, when executed by a processor, implements the steps of the calibration method for any of the electron beam measurement devices described above.

[0015] According to another aspect of the present invention, a computer device is also provided, including a memory, a processor, and a machine-executable program stored in the memory and running on the processor, wherein the processor executes the machine-executable program to implement the steps of the calibration method of any of the above-described electron beam measurement devices.

[0016] The calibration method for the electron beam metrology equipment of the present invention first obtains a calibration formula, which records the reference information of the target calibration area on the detection wafer, indicating the presence of an array of characteristic regions on the detection wafer. Then, the image acquisition position for the electron microscope scanning image is determined according to the calibration formula. An electron beam metrology image is generated at the image acquisition position on the detection wafer using the electron beam metrology equipment. Multiple target feature patterns are identified in the electron beam scanning image according to the calibration formula, and key dimensions of the target feature patterns are measured to obtain the coordinate information corresponding to each target feature pattern. Next, a straight line along the coordinate axis direction of the target feature pattern is obtained by fitting the coordinate information. Finally, the angular deviation of the electron beam metrology equipment is determined based on the straight line, and the angular deviation is compensated for in the electron beam metrology equipment. This method achieves a high degree of automation in the electron beam metrology equipment calibration scheme, completely eliminating result fluctuations caused by differences in human operation, ensuring high consistency and repeatability of calibration operations at different equipment and time points, greatly improving calibration efficiency, and meeting the core requirements of standardization and stability in semiconductor manufacturing.

[0017] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0018] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a schematic diagram of a calibration method for an electron beam measurement device according to an embodiment of the present invention; Figure 2 This is a schematic flowchart of a calibration method for an electron beam measurement device according to another embodiment of the present invention; Figure 3 This is a schematic diagram of detecting a target calibration area on a wafer according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the measurement frame placement according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the edge point annotation result according to an embodiment of the present invention; Figure 6This is a schematic diagram of the centroid coordinate annotation result according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the horizontal line fitted to the centroid before calibration according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the centroid fitting vertical line before calibration according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the included angle of a straight line before calibration according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the horizontal line fitted to the centroid after calibration according to an embodiment of the present invention; Figure 11 This is a schematic diagram of a vertical line fitted to the centroid after calibration according to an embodiment of the present invention; Figure 12 This is a schematic diagram of the included angle of a straight line after calibration according to an embodiment of the present invention; Figure 13 This is a schematic diagram comparing electron microscope scanning images before and after calibration according to an embodiment of the present invention; Figure 14 This is a schematic diagram of a computer program product according to an embodiment of the present invention; Figure 15 This is a schematic diagram of a computer-readable storage medium according to an embodiment of the present invention; and Figure 16 This is a schematic diagram of a computer device according to an embodiment of the present invention. Detailed Implementation

[0019] Those skilled in the art should understand that the embodiments described below are merely a part of the embodiments of the present invention, and not all of the embodiments of the present invention. These partial embodiments are intended to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by those skilled in the art without creative effort should still fall within the scope of protection of the present invention.

[0020] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus or device (such as a computer-based system, a processor-included system or other system that can fetch and execute instructions from, an instruction execution system, apparatus or device).

[0021] In the current semiconductor technology field, the automatic orthogonality calibration of electron beam measurement equipment generally requires acquiring raw image data for orthogonality analysis. However, this typically relies on traditional image binarization and contour extraction algorithms to locate feature points. These methods are sensitive to image noise, contrast variations, and edge blurring, making it difficult to achieve sub-pixel-level feature center localization. This results in significant errors in the extracted feature point positions, leading to insufficient accuracy in the raw data for subsequent angle calculations, ultimately limiting the improvement of the overall system calibration accuracy.

[0022] Secondly, typical calibration methods end the process after performing one compensation, making it impossible to quantitatively verify the actual effect of the compensation. If a deviation occurs in feature extraction or calculation, erroneous compensation results may not be detected and corrected in a timely manner, thus posing a potential risk to the calibration process and resulting in low reliability and confidence of the calibration results.

[0023] Furthermore, conventional calibration methods do not explicitly involve standardized recipes to preserve locations, parameters, and processes. Therefore, each calibration may require manual reselection of areas and setting of parameters. This prevents true one-click automation of the calibration process, resulting in inefficiency and discrepancies between different operators or between different operations, making it difficult to guarantee the consistency of calibrations on the production line.

[0024] In addition, conventional calibration methods lack explicit iterative compensation and anomaly handling logic. Therefore, when the initial calibration fails or the equipment status is unstable, the system may not be able to converge effectively or promptly indicate the anomaly. This results in poor adaptability of the calibration process to fluctuations in actual production, and may even output incorrect results without the user's knowledge.

[0025] To overcome the above-mentioned technical defects, this invention proposes a calibration method for an electron beam measurement device, the specific process of which is as follows: Figure 1 As shown, Figure 1 This is a schematic flowchart of a calibration method for an electron beam measurement device according to an embodiment of the present invention. The calibration method for the electron beam measurement device includes at least the following steps S101 to S106.

[0026] Step S101: Obtain the calibration recipe. The calibration recipe records the reference information of the target calibration area on the detection wafer, indicating the presence of an array-arranged feature region on the detection wafer. For ease of calibration, the target calibration area is generally a region on the wafer with an array-arranged feature, also known as a periodic orthogonal arrangement feature region. An example is... Figure 3 As shown, Figure 3 This is a schematic diagram of detecting a target calibration area on a wafer according to an embodiment of the present invention. Figure 3As can be seen, the features (such as deep holes) in the target calibration area are arranged in a strictly periodic orthogonal pattern, with uniform spacing between adjacent features and consistent geometric shape. This high-density uniform distribution of features can provide sufficient and reliable raw data for fitting and comparison in subsequent steps.

[0027] When performing orthogonality calibration for the first time, an automatic orthogonality calibration recipe needs to be created. This process generally includes: recording the current wafer coordinates, registering a reference image, setting the measurement frame position, relevant measurement parameters, and setting the output parameters as the coordinate information for each hole. Recording the current wafer coordinates is to accurately record the absolute coordinates of the target calibration area on the wafer being inspected, ensuring that the calibration stage can be accurately moved to that position in subsequent calibrations; registering the reference image involves scanning and acquiring a high-resolution SEM image of the target area, which serves as a benchmark for subsequent image matching.

[0028] Here, the measurement box is the measurement region of a single feature shape delineated on the reference image, an optional example being... Figure 4 As shown, Figure 4 This is a schematic diagram of the measurement frame placement according to an embodiment of the present invention. Figure 4 As can be seen from the image, one possible example of the feature image to be measured is a deep hole. The measurement frame is a rectangular measurement window that is separately defined on the reference image for each individual deep hole. The window boundary maintains a fixed distance from the edge of the individual deep hole to ensure that the deep hole outline is completely covered, while isolating the interference of adjacent deep holes. With such a measurement frame, a deep hole can be accurately located, and then multiple deep holes can be determined in batches according to a preset array arrangement to facilitate subsequent fitting.

[0029] By solidifying the key parameters of the initial calibration into a reusable instruction set, i.e. generating a calibration recipe, manual parameter setting is avoided, thus laying the foundation for subsequent fully automated calibration and avoiding subjective errors caused by manual operation.

[0030] Step S102: Determine the image acquisition location of the electron microscope scan image according to the calibration recipe. The image acquisition location refers to the target area on the wafer used for calibration (i.e., the target calibration area recorded in the recipe). This area has complete features and is the core object used for measurement.

[0031] Step S103: Generate an electron microscope scan image at the image acquisition position of the inspected wafer using an electron beam metrology device.

[0032] Since the calibration recipe records the wafer coordinates of the target calibration area, the steps for generating an electron microscope (EMS) image at the image acquisition position of the wafer using an electron beam metrology device generally include: obtaining the wafer coordinates using the calibration recipe; moving the sample stage of the EMS to the position corresponding to the wafer coordinates, thus placing the image acquisition position within the electron beam scanning range; and controlling the EMS to scan the image acquisition position to obtain the EMS image. This operation ensures that the obtained EMS image has the same imaging position as the registered image, guaranteeing that its imaging position is within a pre-selected region with periodic orthogonal or array-like features. This replaces manual operation, reduces human interference (such as manually adjusting scanning parameters or triggering scans), and improves calibration efficiency and accuracy.

[0033] Step S104: Based on the calibration formula, determine multiple feature patterns to be measured in the electron microscope scanning image, and perform key dimension measurements on the feature patterns to obtain the coordinate information corresponding to each feature pattern. Preferably, the feature pattern to be measured can generally be a periodic hole structure defined within the measurement frame. Such deep holes can also be called target holes to be measured, which are the core analysis object of orthogonal calibration. Those skilled in the art can also determine the specific shape of the feature pattern to be measured according to the actual situation.

[0034] Because electron beam measurement equipment may have orthogonal deviations due to scanning coil assembly errors, magnetic field asymmetry, or electron optical distortion, even if the electron beam measurement equipment generates an electron microscope scan image at the image acquisition position, there may still be some deviations. The calibration formula contains the registered image of the target calibration area and the position of the measurement frame in the registered image. At this time, it can be calibrated to determine the feature pattern to be measured in the electron microscope scan image.

[0035] In some optional embodiments, the step of determining multiple target feature patterns in an electron microscope (EM) image according to a calibration formula generally includes: calculating the offset between the registered image and the EM image; determining the corresponding position of the measurement frame in the EM image based on the offset and the measurement frame position; and determining multiple target feature patterns in the EM image based on the measurement frame. This ensures that the measurement objects for each calibration are the same batch of standard holes locked during the initial registration, rather than other holes after offset. This solves the problem of large differences in manual area selection in the prior art, allowing calibrations at different times to be based on the same set of standard features, thus improving the repeatability of the results.

[0036] Specifically, this typically involves comparing a reference image with the current image using an image matching algorithm to identify minute displacements of the target image; then, the coordinates of the measurement box in the current image are corrected based on the offset to ensure that the measurement box always accurately covers the locked feature shape in the reference image, such as... Figure 5 As shown,Figure 5 This is a schematic diagram of the edge point annotation result according to an embodiment of the present invention. Figure 5 The measurement frame 40 in the image is precisely positioned in the deep hole in the electron microscope scan image after correction, which facilitates the subsequent array selection.

[0037] The calibration formula also includes measurement parameters. The steps for determining multiple target feature patterns based on the measurement frame in the electron microscope scanning image generally include: obtaining the array arrangement of the target feature patterns from the measurement parameters; placing the measurement frame according to the array arrangement to select multiple target feature patterns.

[0038] In some optional embodiments, the coordinate information can generally be the centroid coordinates. The steps of performing critical dimension measurement on the feature graphic to obtain the coordinate information corresponding to each feature graphic generally include: annotating the edge points of the feature graphic to obtain the edge points corresponding to each feature graphic; and calculating the centroid coordinates corresponding to each feature graphic based on the edge points. Critical dimension (CD) measurement is a core metrology technology in the semiconductor manufacturing field, specifically referring to the process of accurately measuring the key geometric parameters (such as edge contours and dimensions) of nanoscale graphic structures using high-resolution imaging equipment (such as CD-SEM). An optional example is as follows... Figure 5 As shown, Figure 5 This is a schematic diagram of edge point annotation results according to an embodiment of the present invention. Taking a target hole to be measured as an example, edge point annotation can identify and mark the precise position of the inner wall contour of the target hole point by point. These points together constitute the complete geometric contour of the hole. Subsequently, the geometric center (i.e., the centroid coordinates) of the contour can be fitted based on the edge points, thereby achieving sub-pixel level positioning accuracy. An optional example is as follows: Figure 6 As shown, Figure 6 This is a schematic diagram of the centroid coordinate annotation result according to an embodiment of the present invention. The annotation method of the present invention can accurately locate the edge point and centroid of each deep hole, thereby facilitating subsequent accurate fitting operations and achieving high-precision calibration.

[0039] The critical dimension (CD) measurement + edge point fitting method in this invention can replace the coarse method of traditional binarization + contour extraction to achieve sub-pixel level positioning, thereby reducing the feature positioning error from the pixel level to the nanometer level and solving the core defect of insufficient feature extraction accuracy in the prior art.

[0040] Step S105: A straight line along the coordinate axis direction of the feature image to be measured is obtained by fitting coordinate information. The coordinate information can generally be the centroid coordinates. However, due to the inherent bias in electron beam measurement equipment, the fitted line along the coordinate axis of the feature image will deviate from the actual coordinate axis due to some deviation in the centroid fitting. For example, the straight line obtained after fitting the feature image arranged along the horizontal axis might look like this... Figure 7 As shown, Figure 7 This is a schematic diagram of the horizontal line fitted to the centroid before calibration according to an embodiment of the present invention. The straight line obtained after fitting the measured feature patterns arranged along the vertical axis of the coordinate system is shown below. Figure 8 As shown, Figure 8 This is a schematic diagram of the centroid fitting vertical line before calibration according to an embodiment of the present invention.

[0041] Step S106: Determine the angular deviation of the electron beam measurement device based on the straight line, and compensate the angular deviation into the electron beam measurement device.

[0042] Optionally, the step of determining the angle deviation of the electron beam measurement device based on the straight line generally includes: dividing the straight line into two types based on the coordinate axis direction, and calculating the angle between the two types of straight lines; determining whether the angle deviation between the angle and a right angle is less than a preset threshold; and if the angle deviation is greater than the preset threshold, performing the step of compensating the angle deviation to the electron beam measurement device. The preset threshold is a pre-set error threshold that the electron beam measurement device can accept, and those skilled in the art can set the specific value of the preset threshold according to the actual situation. An optional example of the angle formed by the two types of straight lines is as follows: Figure 9 As shown, Figure 9 This is a schematic diagram of the included angle of a straight line before calibration according to an embodiment of the present invention. Figure 9 It can be seen that the fitted straight line deviates from the coordinate axis direction to a certain extent, failing to meet the orthogonality requirement. This indicates that there is a deviation in the imaging of the electron beam measurement equipment. Therefore, it is necessary to calculate the corresponding angular deviation and perform reverse compensation on the electron beam measurement equipment to complete the orthogonality calibration of the electron beam measurement equipment.

[0043] The method for determining whether the angular deviation between the included angle and the right angle is less than a preset threshold is shown in equation (1): 90°–ε<θ<90°+ε Formula (1) Where θ represents the angle between the two lines, and ε represents the preset threshold; For example, setting the preset threshold to ε=0.01°, Figure 9The angle between the lines in the two coordinate axis directions shown is measured to be 88.1°, which is 1.9° different from the right angle of 90°. This is greater than the preset threshold ε. Therefore, it is determined that the electron beam measurement equipment does not meet the orthogonality requirement and angle compensation is needed. The angle compensation operation generally involves compensating the angle deviation calculated in step S106 into the scanning control module of the electron optical system, and correcting the deflection path of the electron beam by adjusting the drive signal of the scanning coil.

[0044] Optionally, after the step of compensating for the angle deviation in the electron beam measurement device, the process may further include: repeatedly performing the step of generating an electron microscope scan image at the image acquisition position of the inspected wafer using the compensated electron beam measurement device for iterative calibration until the calculated angle deviation is less than a preset threshold; if the angle deviation is still greater than the preset threshold when the number of iterative calibrations reaches the preset maximum number of iterations, the calibration operation is terminated and a prompt message is generated.

[0045] In this embodiment, the specific operation after compensation is as follows: rescan the image at the same location, extract the centroid coordinates again, fit a straight line, and calculate the new included angle θ'. If θ' meets the orthogonality calibration success condition, the calibration is successful, the current orthogonality angle is automatically applied, and the calibration result is recorded. Otherwise, continue the compensation and iterative calibration process until the calibration success condition is met. If the maximum number of iterations is reached and the calibration success condition is still not met, it indicates that the current machine condition is unstable. At this time, the calibration is terminated and a warning message is displayed.

[0046] The final effect after compensation is as follows Figure 10 to Figure 13 As shown, where Figure 10 This is a schematic diagram of the horizontal line fitted to the centroid after calibration according to an embodiment of the present invention; Figure 11 This is a schematic diagram of a vertical line fitted to the centroid after calibration according to an embodiment of the present invention; Figure 12 This is a schematic diagram of the included angle of a straight line after calibration according to an embodiment of the present invention; Figure 13 This is a schematic diagram comparing electron microscope scanning images before and after calibration according to an embodiment of the present invention. Figure 10 It can be seen that the centroid coordinates of all the tested feature graphics are uniformly distributed along the horizontal direction, and the fitted straight line is smooth and regular with no obvious offset, reflecting the consistency of the horizontal feature arrangement after calibration. Figure 11 It can be seen that the centroid coordinates are neatly arranged vertically, and the fitted line is perpendicular to the horizontal fitted line, without any tilt or distortion. From Figure 12 It can be seen that the angle between the horizontal and vertical fitted lines is precisely close to 90°, meeting the preset orthogonality threshold requirement of ε=0.01°, which intuitively proves that the orthogonality deviation between the electron beam and the sample plane has been completely compensated. From Figure 13The images before and after calibration show a clear difference, demonstrating a significant improvement in geometric fidelity after calibration.

[0047] This method perfectly solves the pain points of orthogonality calibration in existing electron beam metrology equipment, with significant and comprehensive technical effects. Regarding calibration accuracy, it employs critical dimension (CD) measurement technology to extract sub-pixel-level centroid coordinates of the aperture structure, replacing traditional binarization and contour extraction algorithms. This significantly reduces positioning errors caused by image noise and edge blurring. Combined with the angle calculation method of fitting straight lines to the centroids of multiple apertures, the calibration accuracy is stably controlled within a preset threshold, meeting the stringent requirements of advanced semiconductor processes. In terms of automation and consistency, standardized calibration recipes solidify key information such as wafer coordinates, reference images, and measurement parameters, enabling unmanned operation throughout the entire process from wafer transfer, positioning, measurement to compensation. This completely eliminates differences in manual operation, ensuring a high degree of consistency in calibration results across different machines and at different times, significantly improving calibration efficiency in mass production environments.

[0048] Figure 2 This is a schematic diagram of a calibration method for an electron beam measurement device according to another embodiment of the present invention, as shown below. Figure 2 As shown, the calibration method of the electron beam measurement device includes at least the following steps S201 to S211.

[0049] Step S201: Obtain the calibration recipe. The calibration recipe is a standardized parameter that needs to be created in advance during the initial calibration of the electron beam measurement equipment. By using the calibration recipe, all parameters required for subsequent automated calibration are recorded, thereby completely eliminating the reliance on manual selection of areas and adjustment of parameters, eliminating result fluctuations caused by differences in manual operation, realizing an automated calibration process, ensuring the repeatability of calibration, and thus significantly improving calibration efficiency.

[0050] Specifically, the calibration recipe can generally include the wafer coordinates of the target calibration area on the wafer, the registration reference image, the measurement frame position, relevant measurement parameters and output parameters (generally the centroid coordinates of each hole), without the need for manual additional settings.

[0051] Step S202: Determine the image acquisition position of the electron microscope scanning image according to the calibration formula, and generate an electron microscope scanning image at the image acquisition position of the wafer being inspected using an electron beam metrology device.

[0052] Optionally, step S202 may typically involve: the system extracting the wafer coordinates of the target calibration region from the calibration formula, driving the sample stage of the electron beam metrology device to automatically move to those coordinates, and precisely locking the image acquisition position; and controlling the electron beam to scan the acquisition position according to the relevant measurement parameters (e.g., accelerating voltage, beam current, scanning speed) in the formula, generating a high-resolution electron microscope image. This image must clearly show the periodic orthogonal features (such as deep hole arrays) on the wafer being tested, without significant noise, charge accumulation, or blurred edges.

[0053] This step can replace the manual visual selection operation in the existing technology, and the wafer coordinate positioning accuracy reaches the nanometer level, ensuring that the measurement area is completely consistent for each calibration, and providing a unified source of raw data for subsequent angle calculation.

[0054] Step S203: Calculate the offset between the registered image and the electron microscope scan image. The registered image is the reference template stored in the calibration recipe (the SEM image of the target area acquired during the initial calibration), and the electron microscope scan image is the real-time image generated by the electron beam metrology device in this step.

[0055] Optionally, an image matching algorithm can be used to compare the relative positions of periodic features in two images and calculate the offset of the standard due to slight vibration, sample stage movement, or other reasons.

[0056] This step allows for the accurate identification of minute displacements in the standard, avoiding calibration errors caused by incorrect or missing holes. This provides data support for subsequent adjustment of the measurement frame position, ensuring that the measurement frame is always aligned with the target features and guaranteeing the consistency of the measured object.

[0057] Step S204: Determine the corresponding position of the measurement box in the electron microscope scanning image based on the offset and the measurement box position, and determine multiple feature patterns to be measured in the electron microscope scanning image based on the measurement box.

[0058] Based on the offset calculated in step S203, the position of the measurement frame recorded in the calibration formula is corrected, and its corresponding coordinates in the current electron microscope scan image are determined. Then, according to the corrected measurement frame position, multiple feature patterns to be measured are determined in the current image based on the array arrangement method preset in the measurement parameters and the positioning of the measurement frame.

[0059] This operation ensures that the measurement objects used in each calibration are from the same batch of standard features, avoiding inconsistent results caused by chaotic measurement areas. It also limits the effective measurement range, filters out distorted and contaminated invalid features, and guarantees the purity of measurement data from the source, laying the foundation for subsequent high-precision centroid calculation.

[0060] Step S205: Mark the edge points of the feature image to be tested to obtain the edge points corresponding to each feature image to be tested, and calculate the centroid coordinates of the feature image to be tested based on the edge points of each feature image to be tested.

[0061] Key dimensions of the feature graphic to be tested are measured, the complete edge of each hole is extracted using a contour fitting algorithm, and the edge position is marked point by point (e.g., Figure 5 The diagram shows the periodic arrangement of deep hole edge points; subsequently, based on the edge point data of each hole, its centroid coordinates are calculated using the geometric center formula, i.e., the X and Y axis coordinates of the geometric center of the hole structure (e.g., ...). Figure 6 The coordinates of the centroids of the periodically arranged deep holes are shown.

[0062] This step replaces the existing binarization and contour extraction algorithms with key dimension measurement technology, solving the shortcomings of traditional methods that are sensitive to noise and edge blurring. It achieves sub-pixel-level feature localization and significantly reduces feature localization errors. Furthermore, the automated execution of edge point annotation and centroid calculation avoids subjective errors caused by manual intervention, ensuring that the centroid coordinates of each hole are accurate and reliable. Ultimately, the centroid coordinates serve as the core data for quantifying feature positions, providing a high-precision original benchmark for subsequent line fitting and angle calculation, fundamentally improving calibration accuracy.

[0063] Step S206: Obtain the horizontal and vertical straight lines of the feature image to be measured by fitting the centroid coordinates. The horizontal straight line is typically fitted by extracting the X-axis data of all centroid coordinates and fitting them using a specific algorithm (e.g., least squares method). (The fitted horizontal straight line is shown in the image.) Figure 7 (As shown). The fitting method for a vertical straight line can also be to extract the Y-axis data of all centroid coordinates and then fit it using an algorithm such as the least squares method to form a vertical straight line (the fitted vertical straight line is shown in the image). Figure 8 (As shown).

[0064] This step fits the centroid coordinates of the multi-hole structure to a straight line. Compared to fitting a single feature point, the fitting result is more stable and effectively reduces the impact of random errors on the linear trend. Furthermore, it transforms the abstract feature arrangement direction into concrete linear parameters, providing a clear mathematical foundation for subsequent angle calculations and enabling quantitative analysis of orthogonality deviation.

[0065] Step S207: Calculate the angle between the horizontal and vertical lines. Based on the horizontal and vertical lines fitted in step S206, calculate the actual angle θ between the two lines using a geometric algorithm (e.g., ...). Figure 9 The diagram shows the angle between the straight line before calibration. This angle directly reflects the orthogonality between the electron beam and the sample plane: the angle is 90° under ideal orthogonal conditions, and the greater the deviation, the worse the orthogonality.

[0066] This step transforms the abstract index of electron beam orthogonality into a precisely quantifiable angle parameter, addressing the current pain point of subjective and ambiguous orthogonality assessment. Simultaneously, the automated angle calculation enables rapid evaluation of orthogonality deviations without requiring manual observation of image features, improving calibration efficiency. Furthermore, the quantified angle data provides a direct basis for subsequent angle compensation, ensuring precise and controllable compensation and avoiding blind adjustments.

[0067] Step S208: Determine whether the angular deviation between the included angle and the right angle is less than a preset threshold. If the determination is yes in step S208, proceed to step S211.

[0068] In some optional embodiments, the method for determining whether the angular deviation between the included angle and the right angle is less than a preset threshold is as shown in equation (1): 90°–ε<θ<90°+ε Formula (1) Where θ represents the angle between the two lines, and ε represents the preset threshold; For example, setting the preset threshold to ε=0.01°, Figure 9 The angle between the lines in the two coordinate axis directions shown is measured to be 88.1°, which is 1.9° different from the right angle of 90°. This is greater than the preset threshold ε. Therefore, it is determined that the electron beam measurement equipment does not meet the orthogonality requirement and angle compensation is needed. Then, step S209 can be executed. If the angle deviation is less than the preset threshold (89.99° < θ < 90.01°), it means that the electron beam orthogonality meets the requirement, and step S211 can be executed directly to end the calibration.

[0069] Step S209: If the determination in step S208 is negative, determine whether the number of iterations for calibration is greater than the preset maximum number of iterations. If the determination in step S209 is positive, proceed to step S211.

[0070] Specifically, if the current number of iterations exceeds the preset maximum number of iterations, it indicates that there may be an abnormality in the device (such as scanning coil failure or standard defect). Step S211 is executed to end the calibration and trigger an alarm. If the number of iterations has not exceeded the upper limit, step S210 is entered to continue compensation.

[0071] This embodiment introduces an iteration limit to address the shortcomings of current technical calibration strategies, such as rigidity and lack of anomaly handling, thereby preventing the system from falling into an infinite loop due to equipment malfunctions and improving the robustness of the calibration system.

[0072] In step S210, if the determination in step S209 is negative, the angle deviation is compensated to the electron beam measurement device, and then step S202 is executed according to the calibrated electron beam measurement device. The angle compensation operation generally involves compensating the angle deviation calculated in step S106 to the scanning control module of the electron optics system, and correcting the deflection path of the electron beam by adjusting the drive signal of the scanning coil.

[0073] After compensation is completed, return to step S202, regenerate the electron microscope scan image based on the calibrated electron beam measurement equipment, and repeat the subsequent measurement, calculation, and judgment process until the angle deviation meets the standard or the number of iterations exceeds the limit.

[0074] Step S211: End the calibration operation.

[0075] As can be seen from the above steps, the automatic orthogonality calibration method provided by this invention brings significant and comprehensive benefits through a series of technological innovations, specifically reflected in the following aspects: 1. Significantly improves calibration accuracy, providing critical metrological assurance for advanced processes. By employing critical dimension (CD) measurement technology to extract the centroid coordinates of each hole, traditional image binarization and contour extraction methods are replaced. This method achieves sub-pixel-level feature center localization, significantly reducing localization errors caused by image noise and edge blurring. It provides an extremely accurate data foundation for subsequent line fitting and angle calculation, fundamentally solving the benchmark error problem caused by coarse feature extraction in existing technologies. Ultimately, the accuracy of orthogonality calibration is stably controlled within an extremely small threshold (e.g., ε=0.01°), meeting the stringent measurement accuracy requirements of advanced nanoscale semiconductor manufacturing processes.

[0076] 2. Enhance the reliability of the calibration process and the credibility of the results.

[0077] A closed-loop control mechanism of "compensation-verification-iteration" was introduced. After performing angle compensation, the system automatically rescans the image and calculates the new included angle θ'. The calibration is only confirmed if the verification result meets the success criteria. This mechanism effectively eliminates erroneous compensation caused by single calculation errors or accidental interference, ensuring that each output calibration result is verified and reliable. This greatly reduces the mass production risk caused by equipment inaccuracies and provides high-confidence process quality control for fully automated production lines.

[0078] 3. Achieve a high degree of automation, significantly improving calibration efficiency and consistency.

[0079] By creating and calling standardized calibration recipes, sample location, measurement parameters, and other details are all fixed. Subsequent calibration can be fully automated, from wafer transfer, positioning, measurement to compensation verification, without human intervention. This not only frees operators from repetitive and subjective manual operations, greatly improving calibration efficiency, but more importantly, it completely eliminates result fluctuations caused by differences in human operation, ensuring high consistency and repeatability of calibration operations across different machines and at different times, meeting the core requirements of standardization and stability in semiconductor manufacturing.

[0080] 4. Improve the system's intelligence and robustness to ensure long-term stable operation.

[0081] The system incorporates intelligent judgment logic, including a maximum number of iterations and an anomaly alarm mechanism. It can automatically handle anomalies such as calibration non-convergence and issue timely alarms, rather than outputting an incorrect result. This enables the calibration system to cope with complex operating conditions such as equipment status fluctuations, significantly improving its practicality and robustness in unattended mass production environments. It can automatically complete routine calibrations and intelligently identify anomalies, ensuring the continuous and stable operation of the production line.

[0082] In summary, through comprehensive optimization of the technical solution, this invention has produced significant beneficial effects in terms of accuracy, reliability, automation level, and intelligence, forming a high-precision, high-efficiency, and high-reliability fully automatic orthogonality calibration solution that can support advanced semiconductor manufacturing.

[0083] It should be understood that in some embodiments, the components may be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods may be implemented using software or firmware stored in memory and executed by a suitable instruction execution system, and any automatic orthogonality calibration scheme for CD measurement based on electron beam images may be considered an alternative to this scheme.

[0084] This embodiment also provides a computer program product 10, a computer-readable storage medium 20, and a computer device 30. Figure 14 This is a schematic diagram of a computer program product 10 according to an embodiment of the present invention. Figure 15 This is a schematic diagram of a computer-readable storage medium 20 according to an embodiment of the present invention. Figure 16This is a schematic diagram of a computer device 30 according to an embodiment of the present invention. The computer program product 10 includes a computer program 11, which, when executed by the processor 32, implements the steps of the calibration method for the electron beam measurement device described above. A computer-readable storage medium 20 stores the computer program 11 thereon, which, when executed by the processor 32, implements the steps of the calibration method for the electron beam measurement device described above. The computer device 30 may include a memory 31, a processor 32, and the computer program 11 stored in the memory 31 and running on the processor 32.

[0085] The computer program 11 used to perform the operations of this invention may be assembly instructions, Instruction Set Architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, integrated circuit configuration data, or source code or object code written in any combination of one or more programming languages ​​and procedural programming languages. The computer program 11 may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer may be connected to the user's computer via any type of network, including a Local Area Network (LAN) or Wide Area Network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, to perform aspects of this invention, electronic circuits, including, for example, programmable logic circuits, Field-Programmable Gate Arrays (FPGAs), or Programmable Logic Arrays (PLAs), may execute computer-readable program instructions to personalize the electronic circuits by utilizing state information from computer-readable program instructions.

[0086] For the purposes of this embodiment, computer program product 10 is a related product containing computer program 11. For the purposes of this embodiment, computer-readable storage medium 20 is a tangible device capable of holding and storing computer program 11, and can be any device capable of containing, storing, communicating, propagating, or transmitting program 11 for use by or in conjunction with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable storage medium 20 include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable optical disc read-only memory (CD-ROM), digital versatile disc (DVD), memory stick, floppy disk, mechanical encoding device, and any suitable combination thereof.

[0087] Computer device 30 can be, for example, a server, desktop computer, laptop computer, tablet computer, or smartphone. In some examples, computer device 30 can be a cloud computing node. Computer device 30 can be described in the general context of computer system executable instructions (such as program modules) executed by a computer system. Typically, program modules can include routines, programs, object programs, components, logic, data structures, etc., that perform specific tasks or implement specific abstract data types. Computer device 30 can be implemented in a distributed cloud computing environment where tasks are performed by remote processing devices linked through a communication network. In a distributed cloud computing environment, program modules can reside on local or remote computing system storage media, including storage devices.

[0088] Computer device 30 may include a processor 32 adapted to execute stored instructions and a memory 31 that provides temporary storage space for the operation of said instructions during operation. The processor 32 may be a single-core processor, a multi-core processor, a computing cluster, or any other configuration. The memory 31 may include random access memory (RAM), read-only memory, flash memory, or any other suitable storage system.

[0089] Computer device 30 may also include a network adapter / interface and an input / output (I / O) interface. The I / O interface allows external devices that can be connected to the computer device to input and output data. The network adapter / interface provides communication between the computer device and a network, typically represented as a communication network.

[0090] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A calibration method for an electron beam measurement device, comprising: A calibration recipe is obtained, wherein the calibration recipe records reference information of a target calibration area on a test wafer, and the test wafer has an array of characteristic regions. Determine the image acquisition location of the electron microscope scanned image according to the calibration formula; An electron microscope scan image is generated at the image acquisition location of the wafer being inspected using an electron beam metrology device; According to the calibration formula, multiple feature patterns to be measured are determined in the electron microscope scanning image, and key dimensions of the feature patterns to be measured are measured to obtain the coordinate information corresponding to each feature pattern to be measured. The straight line along the coordinate axis direction of the feature graphic to be tested is obtained by fitting the coordinate information; The angular deviation of the electron beam measurement device is determined based on the straight line, and the angular deviation is compensated into the electron beam measurement device.

2. The calibration method for the electron beam measurement device according to claim 1, wherein, The calibration recipe includes a registered image of the target calibration region and the position of the measurement frame in the registered image; The step of determining multiple target feature patterns in the electron microscope scanning image according to the calibration formula includes: Calculate the offset between the registered image and the electron microscope scan image; The position of the measurement frame in the electron microscope scan image is determined based on the offset and the position of the measurement frame. In the electron microscope scan image, a plurality of the measured feature patterns are determined according to the measurement frame.

3. The calibration method for the electron beam measurement device according to claim 2, wherein, The calibration formula includes measurement parameters; The step of determining multiple target feature patterns in the electron microscope scan image based on the measurement frame includes: The array arrangement of the feature image to be measured is obtained from the measurement parameters; The measurement frame is placed according to the array arrangement to select multiple feature patterns to be measured.

4. The calibration method for the electron beam measurement device according to claim 1, wherein, The step of determining the angular deviation of the electron beam measurement device based on the straight line includes: The straight line is divided into two types of straight lines with different coordinate axis directions according to the coordinate axis direction, and the included angle between the two types of straight lines is calculated. Determine whether the angular deviation between the included angle and the right angle is less than a preset threshold; If the angle deviation is greater than the preset threshold, the step of compensating the angle deviation into the electron beam measurement device is performed.

5. The calibration method for the electron beam measurement device according to claim 4, wherein, The step of compensating the angle deviation to the electron beam measurement device further includes: The compensated electron beam measurement device is used to repeatedly perform the step of generating an electron microscope scanning image at the image acquisition position of the inspection wafer by the electron beam measurement device for iterative calibration until the calculated angle deviation is less than the preset threshold. If the angle deviation is still greater than the preset threshold when the number of iterations reaches the preset maximum number of iterations, the calibration operation is terminated and a prompt message is generated.

6. The calibration method for the electron beam measurement device according to claim 1, wherein, The coordinate information includes the centroid coordinates; The step of measuring key dimensions of the feature graphics to be measured and obtaining coordinate information corresponding to each feature graphic includes: Edge points are labeled on the feature images to be tested to obtain the edge points corresponding to each feature image to be tested. The centroid coordinates of each feature graphic to be tested are calculated based on the edge points of each feature graphic to be tested.

7. The calibration method for the electron beam measurement device according to claim 1, wherein, The calibration formula includes the wafer coordinates of the target calibration region; The step of generating an electron microscopy image at the image acquisition location of the inspected wafer using an electron beam metrology device includes: The wafer coordinates are obtained using the calibration formula; The sample stage of the electron beam metrology device is moved to the position corresponding to the wafer coordinates, so that the image acquisition position is within the electron beam scanning range; The electron beam measurement device is controlled to scan the image acquisition position to obtain the electron microscope scan image.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that... When the computer program is executed by the processor, it implements the steps of the calibration method for the electron beam measurement device according to any one of claims 1 to 7.

9. A computer program product comprising a computer program that, when executed by a processor, implements the steps of the calibration method for the electron beam measurement device according to any one of claims 1 to 7.

10. A computer device comprising a memory, a processor, and a machine-executable program stored in the memory and running on the processor, wherein the processor, when executing the machine-executable program, implements the steps of the calibration method for an electron beam measurement device according to any one of claims 1 to 7.

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