Method for correcting electron beam landing angle, semiconductor measurement system, and storage medium

Abstract

The application provides a landing angle correction method of an electron beam, a semiconductor measurement system and a storage medium. The correction method comprises the following steps: controlling an electron beam to scan a first measurement feature on a sample to be measured in a first preset direction when the sample to be measured is at a first rotation angle and a second rotation angle which is 180 degrees away from the first rotation angle, respectively; obtaining a first critical dimension and a second critical dimension of the measurement feature according to the scanning results, respectively; inversely calculating deviation information of the landing angle of the electron beam according to the deviation degree of the first critical dimension and the second critical dimension and the geometric parameters of the first measurement feature, and performing iterative feedback correction on the incident state until the deviation is less than a threshold value. The high-precision calibration of the incident angle deviation of the electron beam is achieved, the systematic error caused by the angle inclination is effectively eliminated, and the consistency of the measurement results of multiple measurement devices in the system is ensured.

Description

Technical Field

[0001] This application relates to the field of semiconductor detection technology, specifically to a method for correcting the landing angle of an electron beam, a semiconductor measurement system, and a storage medium. Background Technology

[0002] As semiconductor manufacturing processes continue to advance towards the nanoscale, the feature sizes of integrated circuits are shrinking and the aspect ratios of three-dimensional structures are increasing, placing more stringent demands on the measurement accuracy and consistency across multiple instruments in scanning electron microscopy (CD-SEM). In CD-SEM measurements, the electron beam landing angle—the angle between the incident electron beam and the local normal direction of the sample surface—is one of the key factors affecting the measurement results. Deviations in the electron beam landing angle can lead to asymmetrical distributions of secondary and backscattered electron signals. This is especially problematic when measuring high aspect ratio structures, introducing significant systematic errors that directly impact the accuracy and reliability of critical dimension measurements.

[0003] Currently, controlling the electron beam landing angle mainly relies on passive safeguards. The common practice is to ensure the relative position of the electron optics system and the sample stage through precise machining and assembly during equipment manufacturing, and to perform initial optical calibration during installation to ensure the electron beam is perpendicularly incident under default conditions. In addition, maintaining a stable operating environment and periodically calibrating using standard templates are routine auxiliary methods for maintaining the stability of the electron beam.

[0004] It is evident that existing passive and preventative measures cannot provide real-time, online monitoring and proactive correction of the electron beam landing angle. However, during long-term operation, factors such as component aging, thermal drift, or sample stage tilt inevitably cause unpredictable and slow changes in the actual electron beam landing angle. This angle drift, which cannot be detected and corrected in real time, is the primary cause of long-term drift in measurement results from the same equipment and poor consistency between measurements from different devices. Furthermore, existing methods cannot achieve comprehensive and precise control and compensation of the electron beam landing angle for samples with different geometries and orientations. Summary of the Invention

[0005] The purpose of this application is to overcome the shortcomings of the prior art and provide a method for correcting the landing angle of an electron beam, a semiconductor measurement system, and a storage medium, which can solve the technical problem of reduced consistency and accuracy of measurement results among multiple devices due to non-perpendicular incident electron beam caused by long-term equipment drift, individual differences, and environmental changes.

[0006] In a first aspect, embodiments of this application provide a method for correcting the landing angle of an electron beam, characterized in that it includes:

[0007] When the sample to be tested is at the first rotation angle, the electron beam is controlled to scan the first measurement feature on the sample to be tested in a first preset direction, and the first key dimension of the first measurement feature is obtained according to the scanning result.

[0008] When the sample to be tested is at the second rotation angle, the electron beam is controlled to scan the first measurement feature in the first preset direction, and the second key dimension of the first measurement feature is obtained according to the scanning result; wherein, the second rotation angle differs from the first rotation angle by 180°;

[0009] Based on the deviation between the first critical dimension and the second critical dimension and the geometric parameters of the first measurement feature, the first deviation information of the electron beam landing angle is determined;

[0010] Based on the first deviation information, the incident state of the electron beam is adjusted and iteratively corrected until the deviation between the first critical dimension and the second critical dimension is less than a preset threshold.

[0011] In some embodiments, determining the first deviation information of the electron beam landing angle based on the deviation between the first critical dimension and the second critical dimension and the geometric parameters of the first measurement feature includes:

[0012] Calculate the deviation between the first critical dimension and the second critical dimension;

[0013] Based on the geometry of the first measurement feature cross section, a functional relationship corresponding to the geometry is determined; wherein, the functional relationship is used to define the mathematical relationship between the deviation between the first critical dimension and the second critical dimension and the deviation of the electron beam landing angle;

[0014] Based on the aforementioned functional relationship and the deviation, the deviation of the electron beam landing angle is obtained.

[0015] In some embodiments, the deviation between the first critical dimension and the second critical dimension includes one or more of the difference between the first critical dimension and the second critical dimension, the ratio, and the percentage difference.

[0016] In some embodiments, the cross-section of the first measuring feature is a parallelogram.

[0017] In some embodiments, the cross-section of the first measuring feature is a quadrilateral, and the angle β between its side and the bottom side satisfies: β≤90°-θ, where θ is the electron beam landing angle deviation.

[0018] In some embodiments, determining the functional relationship corresponding to the geometry of the first measured feature cross-section includes:

[0019] Establish a functional relationship between the tangent of the deviation of the electron beam landing angle and the difference between the first critical dimension and the second critical dimension and the height ratio of the first measurement feature.

[0020] In some embodiments, the cross-section of the first measuring feature is a quadrilateral with the top and bottom sides parallel, and the angle β between its side and bottom sides satisfies: β > 90° - θ, where θ is the electron beam landing angle deviation.

[0021] In some embodiments, determining the functional relationship corresponding to the geometry of the first measured feature cross-section includes:

[0022] Establish a functional relationship between the tangent of the deviation of the electron beam landing angle, the difference between the first critical dimension and the second critical dimension, the height ratio of the first measurement feature, and the cotangent of the included angle β.

[0023] In some embodiments, adjusting the incident state of the electron beam based on the first deviation information includes:

[0024] Based on the first deviation information, adjust the excitation current in the X and Y directions of the scanning coil or dedicated correction coil in the scanning electron microscope.

[0025] In some embodiments, the first measurement feature is a protruding structure with sidewalls inclined relative to the sample surface.

[0026] In some embodiments, the method for correcting the electron beam landing angle further includes:

[0027] When the sample to be tested is at the third rotation angle, the electron beam is controlled to scan the second measurement feature on the sample to be tested in the second preset direction, and the third key dimension of the second measurement feature is obtained according to the scanning result;

[0028] When the sample to be tested is at the fourth rotation angle, the electron beam is controlled to scan the second measurement feature in the second preset direction, and the fourth key dimension of the second measurement feature is obtained according to the scanning result;

[0029] Based on the deviation between the third and fourth key dimensions and the geometric parameters of the second measurement feature, the second deviation information of the electron beam landing angle is determined;

[0030] The incident state of the electron beam is adjusted based on the first deviation information and the second deviation information.

[0031] The second measurement feature has a different spatial orientation than the first measurement feature;

[0032] The third rotation angle differs from the fourth rotation angle by 180°, and the third rotation angle differs from the first rotation angle by 90°.

[0033] Secondly, embodiments of this application provide a semiconductor measurement system, including:

[0034] The sample stage is used to hold and rotate the sample to be tested.

[0035] A scanning electron microscope is used to generate and scan electron beams;

[0036] A processor, communicatively connected to the sample stage and the scanning electron microscope; the processor is configured to perform a method for correcting the electron beam landing angle as described in any embodiment of the first aspect.

[0037] Thirdly, embodiments of this application provide a computer-readable storage medium storing a computer-executable program or instructions, which, when executed by a processor, are used to implement the electron beam landing angle correction method as described in any embodiment of the first aspect.

[0038] The electron beam landing angle correction method and semiconductor measurement system provided in this application embodiment achieve high-precision calibration of electron beam incident angle deviation by symmetrically measuring the sample under test by rotating it 180° relative to the axis of the electron beam incident direction. Utilizing the key dimensional differences obtained from measuring the same feature before and after the rotation, combined with characteristic geometric parameters, the deviation information of the electron beam landing angle is inferred. Based on this, iterative feedback correction of the incident state is performed until the deviation is less than a threshold, cleverly realizing high-precision calibration of the electron beam incident angle deviation. This application, based on the 180° rotation design, effectively eliminates interference factors such as sample surface morphology and process fluctuations, establishing a unique mapping relationship between angle error and dimensional deviation, significantly improving correction accuracy and efficiency. Simultaneously, the iterative adjustment mechanism ensures that the electron beam is ultimately incident in a nearly perpendicular state, effectively eliminating systematic errors caused by angle tilt, guaranteeing the consistency of measurement results from multiple measurement devices, and greatly improving the repeatability and accuracy of key dimension measurements. This provides reliable process control and quality inspection methods for high-precision fields such as semiconductor manufacturing and nanomaterial characterization.

[0039] In addition, this application also provides a computer-readable storage medium that has the same beneficial effects as the clock error compensation method described above. Attached Figure Description

[0040] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0041] Figure 1A flowchart illustrating a method for correcting the electron beam landing angle according to an embodiment of this application;

[0042] Figure 2 A flowchart illustrating a method for correcting the electron beam landing angle according to another embodiment of this application;

[0043] Figure 3 A flowchart illustrating a method for correcting the electron beam landing angle according to another embodiment of this application;

[0044] Figure 4 A schematic diagram of the structure of a measurement feature provided in one embodiment of this application;

[0045] Figure 5 This is a cross-sectional schematic diagram of the first measurement feature provided in Embodiment 1 of this application at a first rotation angle;

[0046] Figure 6 This is a cross-sectional schematic diagram of the first measurement feature provided in Embodiment 1 of this application at a second rotation angle;

[0047] Figure 7 A schematic diagram of the ideal incident state of the electron beam provided in Embodiment 1 of this application;

[0048] Figure 8 This is a cross-sectional schematic diagram of a first measurement feature at a first rotation angle, provided in Embodiment 2 of this application.

[0049] Figure 9 This is a cross-sectional schematic diagram of a first measurement feature at a second rotation angle, provided in Embodiment 2 of this application.

[0050] Figure 10 This is a cross-sectional schematic diagram of another first measurement feature provided in Embodiment 2 of this application at a first rotation angle;

[0051] Figure 11 This is a cross-sectional schematic diagram of another first measurement feature provided in Embodiment 2 of this application at a second rotation angle;

[0052] Figure 12 This is a cross-sectional schematic diagram of another first measurement feature provided in Embodiment 2 of this application under a first rotation angle;

[0053] Figure 13 This is a cross-sectional schematic diagram of another first measurement feature provided in Embodiment 2 of this application at a second rotation angle;

[0054] Figure 14 This is a cross-sectional schematic diagram of the first measurement feature provided in Embodiment 3 of this application at a first rotation angle;

[0055] Figure 15This is a cross-sectional schematic diagram of the first measurement feature provided in Embodiment 3 of this application at a second rotation angle;

[0056] Figure 16 This is a cross-sectional schematic diagram of the first measurement feature provided in Embodiment 4 of this application at a first rotation angle;

[0057] Figure 17 This is a cross-sectional schematic diagram of the first measurement feature provided in Embodiment 4 of this application at the second rotation angle;

[0058] Figure 18 This is a schematic diagram of the structure of a semiconductor measurement system provided in one embodiment of this application.

[0059] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0060] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. Similar elements in different embodiments are referred to by related similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the present application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present application are not shown or described in the specification. This is to avoid obscuring the core parts of the present application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0061] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0062] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class, without limiting the number of objects; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship. Unless otherwise specified, the terms "connection" and "linkage" used in this application include both direct and indirect connections (linkages).

[0063] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0064] In semiconductor metrology systems, when measuring critical dimensions of a sample using an electron microscope, it is crucial to ensure that the electron beam emitted from the microscope strikes the sample surface at an angle as perpendicular as possible to minimize the impact of secondary electrons emitted or backscattered from the sample surface on the measurement results. Therefore, uniformly correcting the landing angle of the electron beam for each device before scanning is a critical prerequisite for eliminating inherent errors between devices and ensuring the accuracy and consistency of cross-platform measurement data.

[0065] Figure 1 This is a flowchart illustrating a method for correcting the electron beam landing angle according to one embodiment of this application. Figure 1 As shown, the electron beam landing angle correction method provided in this embodiment is applied to scanning electron microscopy, especially for measuring the dimensions of fine patterns formed on semiconductor wafers, such as the linewidth of photoresist patterns, the diameter of etched contact holes / vias, and the gate line width, as well as other critical dimensions (CD) in scanning electron microscopy. The correction method specifically includes the following steps:

[0066] Step S110: When the sample to be tested is at the first rotation angle, control the electron beam to scan the first measurement feature on the sample to be tested in the first preset direction, and obtain the first key dimension of the first measurement feature based on the scanning result.

[0067] The semiconductor sample to be tested is moved into the field of view of the electron microscope by a motion platform and rotated and fixed at an initial position, namely the first rotation angle. At this time, the electron beam is controlled by the scanning control system of the electron microscope to scan the first measurement feature on the sample surface along the first preset direction.

[0068] In some embodiments, the first rotation angle can be 0° or a specific reference angle, and the first preset direction can be a horizontal direction or a fixed vector direction. The first measurement feature can be a key structure on the sample surface, such as a standard linewidth structure, a periodic grating, or a test pattern with known geometric parameters, which can be used to evaluate the imaging quality of the electron beam.

[0069] During the scanning process, the secondary electron or backscattered electron signals generated by the interaction between the electron beam and the sample surface are captured by the detector. After signal processing, the corresponding data or image of the measurement feature is generated. The key dimension of the first measurement feature, namely the first key dimension, CD1, is extracted by specific geometric relationships or image analysis algorithms (such as edge detection, threshold segmentation or model fitting). This is the key dimension for obtaining the measurement feature of the sample surface, such as line width, spacing or diameter.

[0070] In some embodiments, the first measurement feature is a protruding structure with sidewalls tilted relative to the sample surface.

[0071] Choosing a protruding structure with sidewalls tilted relative to the sample surface as a measurement feature, such as a trapezoidal stage, wedge, or micro / nano pillar with an oblique cut, aims to effectively amplify and highlight the measurement error caused by electron beam landing angle deviation. Specifically, the tilted sidewall itself is an asymmetrical geometry. When an electron beam with an incident angle deviation scans it, the interaction between the electron beam and the sidewall is highly dependent on the relative angle, causing significant distortion in the resulting image contour. For example, one sidewall may appear brighter, wider, or shifted in position in the image. When the sample is rotated 180 degrees, the original tilted sidewall's direction relative to the fixed electron beam deviation reverses. This causes a significant and predictable change in the direction and degree of image distortion between the two scans, thus geometrically amplifying the difference between the two key dimension measurements. This amplification effect allows for clearer and more sensitive detection of minute landing angle deviations, greatly improving the signal-to-noise ratio of subsequent deviation calculations and the efficiency and accuracy of the entire iterative correction process.

[0072] Step S120: When the sample to be tested is at the second rotation angle, control the electron beam to scan the first measurement feature in the first preset direction, and obtain the second key dimension of the first measurement feature based on the scanning result.

[0073] After completing the measurement of the first critical dimension, the sample to be measured is removed from the field of view of the electron microscope again by the motion platform, and rotated around the axis perpendicular to the electron beam incident plane until the second rotation angle is symmetrical to the first rotation angle. Then, the electron beam is controlled by the scanning control system of the electron microscope to scan the same first measurement feature in the same first preset direction as in step S110 to obtain the critical dimension for acquiring the first measurement feature, namely the second critical dimension, CD2.

[0074] Because the measured sample is rotated, the position of the measurement features changes, and the interaction conditions between the electron beam and the sample surface also change. The deviation in the electron beam landing angle—that is, the angle between the electron beam incident direction and the sample surface normal—will lead to changes in the scanning results. By re-extracting the key dimensions after rotation through scanning and data / image processing, and comparing them with the measurement results before rotation, the systematic error caused by the electron beam landing angle deviation can be separated, allowing us to focus only on the impact of the electron beam landing angle deviation on the measurement results.

[0075] In some embodiments, the second rotation angle differs from the first rotation angle by 180°.

[0076] The core purpose of setting the second rotation angle to differ from the first rotation angle by 180° is to establish a comparative benchmark for angular errors through symmetrical sample rotation, thereby highlighting the measurement error caused by the electron beam landing angle deviation. When the sample is rotated 180°, the geometric orientation of the same measurement feature is completely reversed. Any inherent, direction-independent geometric asymmetry on the sample will be presented to the electron beam in the same direction in both measurements, thus its impact on the two critical dimension measurements is the same. However, the preset scanning direction of the electron beam remains unchanged in both measurements. The electron beam landing angle deviation, as a fixed directional error relative to the electron beam cylinder, will manifest as two opposing forces relative to the measured feature before and after sample rotation.

[0077] Specifically, in the first measurement, if there is a tilt deviation in the actual landing angle of the electron beam (such as non-perpendicular incidence), the tilt will cause the image on one side of the feature to be magnified. In the second measurement after rotating 180°, this magnified image will shift to the other side of the feature. Therefore, the measured feature before and after rotation will produce quantifiable dimensional differences due to changes in projection geometry, such as the deviation delta CD between the linewidth measurements CD1 and CD2. This difference is caused only by the deviation of the electron beam incident angle and is unrelated to the sample's morphology or process variations. Therefore, by analyzing delta CD and combining it with the known geometric parameters of the measured feature, the actual deviation of the electron beam landing angle can be accurately deduced, providing a unique and clear basis for the error direction and magnitude for subsequent corrections.

[0078] Step S130: Determine the first deviation information of the electron beam landing angle based on the deviation between the first key dimension and the second key dimension and the geometric parameters of the first measurement feature.

[0079] Based on the first critical dimension (CD1) and the second critical dimension (CD2) obtained in the first two steps, the deviation between them is calculated, and combined with the geometric parameters of the first measurement feature, the first deviation information of the electron beam landing angle is derived. The first deviation information typically includes the magnitude and direction of the deviation of the electron beam incident angle, such as the deflection angle relative to the sample normal.

[0080] In some embodiments, the deviation between the first critical dimension and the second critical dimension is used to reflect the degree of deviation between the two. The deviation between the first critical dimension and the second critical dimension can be the absolute difference, relative difference, or percentage difference between the two, or it can be the ratio or absolute ratio between the two, or it can be a combination of multiple deviation indicators.

[0081] The "deviation" between the first and second critical dimensions is a comprehensive indicator used to quantify the degree of difference between them. The most suitable mathematical expression can be selected based on the specific measurement accuracy requirements, the magnitude of the feature dimensions, and the subsequent algorithm model. The simplest and most intuitive option is the absolute difference (|CD1-CD2|), which directly reflects the absolute value of the size difference. Alternatively, a relative difference ((CD1-CD2) / CD1) or a percentage difference ((CD1-CD2) / CD1*100%), which eliminates the influence of dimensions, can be chosen to more fairly assess the deviation of different size features, normalize the degree of deviation, and facilitate the setting of a unified preset threshold. Meanwhile, the ratio (CD2 / CD1) or the absolute ratio (|CD2 / CD1-1|) is another dimensionless measurement scale. It characterizes the degree of deviation of symmetry through the ratio relationship between the two dimensions, which may be more convenient for subsequent angle calculation models. In addition, combinations of various deviation forms can be selected, such as weighted combination of percentage difference and ratio, to construct a more comprehensive and stable evaluation index, thereby overcoming the limitations that a single index may have, such as the absolute difference being insignificant under small size features, or the percentage difference being not sensitive enough under large size features. Ultimately, this ensures that the first deviation information extracted from the measurement difference can more reliably reflect the true incident angle error of the electron beam.

[0082] The flexible definition of deviation can adapt to the needs of different measurement scenarios. For example, in semiconductor manufacturing, absolute difference can intuitively reflect nanoscale size fluctuations, while relative error or ratio is more suitable for comparative analysis across process nodes or different design specifications, thus providing a more comprehensive and customizable error judgment basis for electron beam landing angle correction.

[0083] In some embodiments, the geometric parameters of the first measurement feature can be obtained through prior knowledge or independent measurement, and are used to establish a geometric projection model or error transfer function between the deviation and the landing angle deviation. Based on the deviation between the first and second key dimensions, and combined with the known geometric parameters of the first measurement feature, the deviation of the actual electron beam landing angle relative to the theoretical incident direction is calculated using the geometric projection model or error transfer formula. For example, if the measurement feature is a rectangular linewidth, the dimensional difference after rotating 180° can be attributed to the change in effective projected length caused by the electron beam incident angle, thereby deducing the tilt direction and magnitude of the landing angle.

[0084] Step S140: Adjust the incident state of the electron beam according to the first deviation information and perform iterative correction until the deviation between the first critical dimension and the second critical dimension is less than a preset threshold.

[0085] Based on the first deviation information, the incident state of the electron beam is adjusted in real time through the beam control system of the electron microscope. After adjustment, steps S110-S130 are repeated to measure the critical dimensions before and after rotation and calculate the new deviation until the deviation between the first and second critical dimensions is less than a preset threshold. The deviation is gradually reduced through an iterative process to ensure that the electron beam is incident on the sample at a near-perpendicular angle, eliminating systematic errors caused by angular deviation, improving the accuracy and repeatability of critical dimension control, and ensuring the consistency of measurement results among multiple measurement devices in the measurement system.

[0086] In some embodiments, adjusting the incident state of the electron beam based on the first deviation information specifically includes:

[0087] Based on the first deviation information, adjust the excitation current in the X and Y directions of the scanning coil or dedicated correction coil in the scanning electron microscope.

[0088] It is understandable that the scanning coil or dedicated calibration coil in a scanning electron microscope is essentially an electromagnet. When an excitation current is supplied to it in the X and Y directions, a magnetic field of corresponding magnitude and direction is generated. When the electron beam passes through this magnetic field, it is subjected to the Lorentz force, and its flight path is deflected in a controllable manner.

[0089] The first deviation information includes the angle and magnitude of the electron beam's deviation from the sample normal in the X and Y directions, i.e., the tilt component of the electron beam landing angle in the X / Y directions. This first deviation information is converted into a correction signal, which is directly used to adjust the excitation current applied to the coil. For example, if a +0.5° tilt deviation of the electron beam in the X direction is detected, the X-direction coil current is reduced to decrease the positive deflection magnetic field, or the reverse current is increased to counteract the deviation, restoring the electron beam to a near-perpendicular incident state. This electromagnetically controlled correction method features high response speed and nanometer-level precision, enabling rapid and precise fine-tuning of the electron beam's incident state (i.e., landing angle) at the source without physically moving the electron gun or sample stage, thereby calibrating the electron beam to an ideal state perpendicular to the sample surface.

[0090] In summary, the electron beam landing angle correction method provided in this embodiment achieves high-precision calibration of the electron beam incident angle deviation by performing a symmetrical measurement of the sample under test rotated 180° relative to the axis of the electron beam incident direction. Utilizing the key dimensional differences obtained from measuring the same feature before and after the rotation, combined with characteristic geometric parameters, the deviation information of the electron beam landing angle is inferred. Based on this, iterative feedback correction of the incident state is performed until the deviation is less than a threshold, cleverly realizing high-precision calibration of the electron beam incident angle deviation. This method, based on a 180° rotation design, effectively eliminates interference factors such as sample surface morphology and process fluctuations, establishing a unique mapping relationship between angle error and dimensional deviation, significantly improving correction accuracy and efficiency. Simultaneously, the iterative adjustment mechanism ensures that the electron beam is ultimately incident in a nearly perpendicular state, effectively eliminating systematic errors caused by angle tilt, guaranteeing the consistency of measurement results from multiple measurement devices, and greatly improving the repeatability and accuracy of key dimension measurements. This provides a reliable process control and quality inspection method for high-precision fields such as semiconductor manufacturing and nanomaterial characterization.

[0091] Figure 2 A flowchart illustrating a method for correcting the electron beam landing angle according to another embodiment of this application. Figure 2 As shown, based on any of the above embodiments, step S130, determining the first deviation information of the electron beam landing angle according to the deviation between the first key dimension and the second key dimension and the geometric parameters of the first measurement feature, specifically includes the following steps:

[0092] Step S1301: Calculate the deviation between the first critical dimension and the second critical dimension.

[0093] By comparing the first critical dimension (CD1) and the second critical dimension (CD2) obtained from two scans of the sample before and after a 180° rotation, the absolute difference, relative difference, or other quantitative indicators between the two are calculated to convert them into standardized mathematical quantities that can be processed by subsequent models. For example, if CD1 = 100 nm and CD2 = 105 nm, the absolute difference is 5 nm and the relative difference is 5%, indicating that the dimension increased by 5% due to the angular deviation after rotation.

[0094] Step S1302: Determine the functional relationship corresponding to the geometry based on the geometry of the first measurement feature cross section; wherein, the functional relationship is used to define the mathematical relationship between the deviation between the first key dimension and the second key dimension and the deviation of the electron beam landing angle.

[0095] Different sample features, such as vertical sidewalls, inclined sidewall lines, or protrusions, exhibit different geometrical optical principles of imaging distortion when scanned by an inclined electron beam. Therefore, by analyzing the cross-sectional geometry of the first measurement feature (e.g., trapezoidal, wedge-shaped, or oblique), a mathematical model describing the physical relationship between its critical dimensions and the electron beam incident angle can be established. Based on this model, a specific mathematical function F can be derived. This function clearly defines the quantitative connection between the deviation D calculated in the previous step and the electron beam landing angle deviation θ to be determined, i.e., D = F(θ, geometric parameters). This functional relationship typically involves trigonometric geometry, linking the electron beam tilt angle, the sidewall angle of the feature, and the changes in critical dimensions, thus establishing a reverse calculation bridge from the deviation to the angular deviation.

[0096] Step S1303: Obtain the deviation of the electron beam landing angle based on the functional relationship and the deviation.

[0097] Substituting the dimensional deviation obtained in step S1301 into the functional relationship determined in step S1302, the actual deviation of the electron beam landing angle is calculated through algebraic operations or numerical solution methods (such as inverse trigonometric functions or iterative approximation). This calculated deviation is the core of the "first deviation information," which clearly indicates how much the current incident direction of the electron beam deviates from the ideal perpendicular direction, and the direction of deviation can be inferred from the model (e.g., based on whether CD1 or CD2 is larger). This provides precise numerical instructions for performing accurate and directional electron beam calibration in the next step.

[0098] Figure 3 A flowchart illustrating a method for correcting the electron beam landing angle according to another embodiment of this application. Figure 3 As shown, the electron beam landing angle correction method provided in this embodiment specifically includes the following steps:

[0099] Step S310: When the sample to be tested is at the first rotation angle, control the electron beam to scan the first measurement feature on the sample to be tested in the first preset direction, and obtain the first key dimension of the first measurement feature based on the scanning result.

[0100] Step S320: When the sample to be tested is at the second rotation angle, control the electron beam to scan the first measurement feature in the first preset direction, and obtain the second key dimension of the first measurement feature based on the scanning result.

[0101] Step S330: Determine the first deviation information of the electron beam landing angle based on the deviation between the first key dimension and the second key dimension and the geometric parameters of the first measurement feature.

[0102] It should be noted that steps S310-S330 are implemented in the same way as steps S110-S130 in any of the above embodiments, and will not be repeated here to avoid repetition.

[0103] Step S340: When the sample to be tested is at the third rotation angle, control the electron beam to scan the second measurement feature on the sample to be tested in the second preset direction, and obtain the third key dimension of the second measurement feature based on the scanning result.

[0104] To comprehensively calibrate the electron beam, this embodiment, based on any of the above embodiments, further introduces a correction process for the electron beam landing angle in another direction. In step S340, the sample to be tested is placed at a new third rotation angle, which is different from the first and second rotation angles in step S310; simultaneously, the electron beam will also switch to a second preset direction different from the first preset direction for scanning. For example, if the first preset direction is the X direction, the second preset direction can be the Y direction. At this time, the electron beam scans the second measurement feature on the sample. This feature may be the same as or different from the first feature, but its geometric parameters are known. Subsequently, based on the scanning results, its third critical dimension (CD3) is obtained to capture the incident state information of the electron beam in the second direction.

[0105] In some embodiments, the second measurement feature has a different spatial orientation than the first measurement feature.

[0106] Figure 4 This is a schematic diagram of the structure of a measurement feature provided in one embodiment of this application. Figure 4 As shown, the measurement feature has tilt features 1 and 2, which are the first measurement feature and the second measurement feature, respectively. The first measurement feature is a vertically tilted boss, which represents the protrusion structure in the Y-axis direction, and the second measurement feature is a horizontally tilted boss, which represents the protrusion structure in the X-axis direction.

[0107] like Figure 4As shown, the spatial orientation of the first measurement feature makes it most sensitive to the landing angle deviation of the electron beam in the XZ plane, because the deviation causes the electron beam to strike its sidewall at an angle, resulting in a significant change in the measured critical dimensions. However, the component of the same deviation in the YZ plane has little effect on the structure with this Y orientation. Therefore, in order to detect and quantify the angular deviation in the YZ plane with the same accuracy, a measurement feature with a different orientation in spatial distribution than the first measurement feature is selected as the second measurement feature. The second measurement feature is not sensitive to deviations in the XZ plane, but can respond sensitively to deviations in the YZ plane.

[0108] This means that the first and second measurement features exhibit spatial characteristics such as extension direction and angular relationship on the surface of the sample under test. These different spatial orientation characteristics allow the electron beam landing angle to be reflected from different dimensions after scanning them with different rotation angles and preset directions to obtain key dimensions. This provides a more comprehensive and reliable basis for accurately determining the deviation information of the electron beam landing angle, and helps to more accurately adjust the incident state of the electron beam.

[0109] Step S350: When the sample to be tested is at the fourth rotation angle, control the electron beam to scan the second measurement feature in the second preset direction, and obtain the fourth key dimension of the second measurement feature based on the scanning result.

[0110] To achieve symmetrical measurement in the second preset direction, this step rotates the sample to a fourth rotation angle while the electron beam continues scanning the second measurement feature in the second preset direction. Based on the results of this scan, the fourth critical dimension (CD4) of the second measurement feature is determined. The 180° rotation of the sample causes a deviation in the electron beam's landing angle in the second preset direction, resulting in a difference between the two critical dimension measurements. This difference reveals the dimensional measurement deviation caused by the electron beam's landing angle in the second scanning direction plane, which is entirely consistent with the principle of steps S310-S320 in the first preset direction.

[0111] In some embodiments, the third rotation angle differs from the fourth rotation angle by 180°, and the third rotation angle differs from the first rotation angle by 90°.

[0112] In order to accurately calculate the electron beam landing angle deviation in the two-dimensional plane, the third and fourth rotation angles were set to differ by 180° during multiple measurements. The purpose was the same as the first set of measurements: to eliminate the influence of the asymmetry of the sample features through symmetry transformation, thereby isolating the size difference caused by the electron beam deviation in the second measurement direction.

[0113] Based on this, a 90° difference was also set between the third rotation angle and the first rotation angle. This means that the overall coordinate system of the second set of measurements was rotated 90° relative to the first set of measurements. This setting makes the two sets of measurements have different directional sensitivities to the electron beam landing angle deviation. It decomposes a two-dimensional landing angle deviation vector into two independently measurable and calculable, mutually perpendicular one-dimensional deviation components. This helps to obtain the key dimensions of different measurement features more comprehensively and accurately, thereby more accurately determining the deviation information of the electron beam landing angle, and ultimately achieving effective adjustment of the electron beam incident state.

[0114] In some embodiments, the first rotation angle is set to 0°, the corresponding second rotation angle is 180°, the third rotation angle is 90°, and the fourth rotation angle is 270°.

[0115] The scheme employing four key angles—0°, 90°, 180°, and 270°—is extremely simple and efficient in mathematical modeling because it perfectly corresponds to the two principal axes of the Cartesian coordinate system. This allows the calculation of deviation components to be performed independently and directly synthesized without the need for complex angle transformations. At the same time, it achieves a high degree of standardization and repeatability in the operation process, facilitating automatic system execution and unified processing of calibration algorithms. Thus, while ensuring calibration accuracy, it improves the robustness and efficiency of the entire correction process.

[0116] Step S360: Determine the second deviation information of the electron beam landing angle based on the deviation between the third and fourth key dimensions and the geometric parameters of the second measurement feature.

[0117] This step is parallel to step S330. Based on the deviation between the third key dimension obtained in step S340 and the fourth key dimension obtained in step S350, and combined with the geometric parameters of the second measurement feature itself, the landing angle deviation of the electron beam in the second preset direction is determined using the corresponding function model, i.e., the second deviation information.

[0118] Step S370: Adjust the incident state of the electron beam according to the first deviation information and the second deviation information, and perform iterative correction until the deviation is less than the preset threshold.

[0119] After obtaining the first and second deviation information from two mutually perpendicular (or different) measurement planes, the electron beam landing angle deviation reflected by these two sets of deviation information is used to adjust the incident state of the electron beam, such as the incident angle and incident position, to ensure accurate landing. Specifically, based on this synthesized and comprehensive deviation information, the excitation current correction amount in both the X and Y directions that needs to be applied to the scanning coil or correction coil is precisely calculated. This allows for a one-time or iterative adjustment of the electron beam's incident state, ultimately ensuring it is perpendicular to the sample surface, achieving high-precision comprehensive calibration.

[0120] The correction method in this embodiment eliminates the influence of the feature's own asymmetry by measuring the first rotation angle and the second rotation angle that is 180° different from it, and further measures the orthogonal direction at the third and fourth rotation angles that are 90° different from it. This successfully decomposes the two-dimensional electron beam landing angle deviation, which is difficult to observe directly, into two independent and precisely quantifiable directional components. This design enables the method to comprehensively and accurately obtain the complete deviation vector of the electron beam in space, thereby realizing precise closed-loop control of the excitation current of the scanning coil or correction coil. Ultimately, it effectively overcomes the limitations of single-direction calibration and greatly improves the accuracy, repeatability, and overall instrument performance reliability of scanning electron microscopes and other equipment in measuring key dimensions on complex morphological samples.

[0121] In some embodiments, the cross-sections of the first and second measuring features are quadrilaterals, specifically parallelograms or irregular quadrilaterals.

[0122] The following examples illustrate, using several common measurement features with quadrilateral cross-sections, to detail the process of constructing the functional relationship between the deviation of the first and second critical dimensions and geometric parameters, and solving for the deviation of the electron beam landing angle. (The calculation of the deviation between the third and fourth critical dimensions is similar.)

[0123] Example 1:

[0124] by Figure 4 Taking the measurement feature structure shown as an example, Figure 5 and Figure 6 These are schematic diagrams of the AA cross-section of the first measurement feature in the measurement structure at the first rotation angle (0°) and the second rotation angle (180°). Figure 5 and Figure 6 As shown, in this embodiment, the cross-section of the first measuring feature is a parallelogram. Its geometric parameters can be known by measurement. The height of the first measuring feature is denoted as h, the length of the bottom side is denoted as X0, and the angle between the side and the bottom side (in this embodiment, the bottom side is consistent with the horizontal direction) is denoted as α.

[0125] At the first rotation angle, when the electron beam is as Figure 5 When scanning the first measurement feature from left to right in the direction shown, due to the existence of a landing angle theta (θ), based on the emission characteristics and imaging characteristics of secondary electrons in the scanning electron microscope at the feature size, the following can be obtained: Figure 5 The result for the first critical dimension CD1 is shown. Further, the sample is removed and rotated to the second rotation angle, maintaining the same position as before. The first measurement feature is scanned again from left to right, yielding the result shown below. Figure 6 The result of the second critical dimension CD2 is shown.

[0126] From such Figure 5 and Figure 6 It can be seen that due to the existence of the electron beam landing angle theta(θ), the first critical dimension CD1 and the second critical dimension CD2 are not equal. At this time, the absolute difference between the two can be selected as an indicator to measure the degree of deviation between them, that is, the deviation between CD1 and CD2 is delta CD=|CD1-CD2|.

[0127] Further construct the functional relationship between the deviation between the first and second critical dimensions and the geometric parameters, based on... Figure 5 and Figure 6 From the geometric model shown, we can see that:

[0128] exist Figure 5 In, CD1=CE=CD+DE=AB+DE=(AF+FB)+DE=(X0+h / tan(α) )+DE=X0+h / tan(α)+h*tan(θ);

[0129] exist Figure 6 In, CD2=C'D'=A'B'-B'F'=A'E'+E'B'-B'F'=h / tan(α)+X0-h*tan(θ);

[0130] From the above formula, we can obtain: delta CD = CD1 - CD2 = 2h * tan(θ);

[0131] Further solving yields: theta(θ) = arctan(delta CD / 2h).

[0132] It can be seen that the tangent of the deviation of the electron beam landing angle is positively correlated with the difference between the first critical dimension and the second critical dimension and the height ratio of the first measurement feature.

[0133] As mentioned earlier, after calculating the electron beam landing angle theta(θ), it is corrected using a scanning coil or a dedicated angle correction coil. The magnitude of theta is adjusted by changing the excitation current or the X / Y current ratio in the X and Y directions of the scanning coil or landing angle correction coil. Due to measurement and calculation errors, a single correction is usually insufficient to completely correct the theta angle. Therefore, multiple iterations of measurement and correction are necessary until delta CD = 0, until the electron beam landing angle theta is zero or infinitely close to zero. Figure 7 The final state shown is CD1=CD2, as follows: Figure 7 As shown, the electron beam is incident on the sample at a nearly perpendicular angle, and the first measurement feature is measured again. The results of the symmetrical measurement show that there is no deviation between the key dimensions or the deviation meets the preset threshold requirements.

[0134] Considering the special structural characteristics of parallelograms, the above method is used to verify whether it is applicable to ordinary quadrilaterals.

[0135] Example 2:

[0136] Figure 8 and Figure 9 These are schematic diagrams of the AA section of a measurement structure, showing the first measurement feature at a first rotation angle (0°) and a second rotation angle (180°). Figure 8 and Figure 9 As shown, in this embodiment, the cross-section of the first measuring feature is quadrilateral, and its top and bottom edges are parallel. Its geometric parameters can be determined through measurement. Let the height of the first measuring feature be h, the length of its bottom edge be X0, the angle between one side edge and the bottom edge (in this embodiment, the bottom edge is aligned with the horizontal direction) be α, and the angle between the other side edge and the bottom edge be β, satisfying β ≤ 90° - θ, where θ is the electron beam landing angle deviation. Figure 5 and Figure 6 The calculation steps involve constructing a functional relationship between the deviation of the first critical dimension and the second critical dimension and the geometric parameters, and solving for the deviation of the electron beam landing angle. The results are: delta CD = CD1 - CD2 = 2h * tan(θ), theta(θ) = arctan(deltaCD / 2h).

[0137] Figure 10 and Figure 11 These are schematic diagrams of the AA section of another measurement structure, showing the first measurement feature at a first rotation angle (0°) and a second rotation angle (180°). Figure 10 and Figure 11As shown, in this embodiment, the cross-section of the first measuring feature is quadrilateral, but its top and bottom edges are not parallel. Its geometric parameters can be determined through measurement. Let the height of the first measuring feature be h, the length of the bottom edge be X0, the angle between one side and the bottom edge (in this embodiment, the bottom edge is aligned with the horizontal direction) be α, and the angle between the other side and the bottom edge be β, satisfying β≤90°-θ, where θ is the electron beam landing angle deviation. Using the above solution process, we can still obtain: delta CD = CD1 - CD2 = 2h * tan(θ), theta(θ) = arctan(delta CD / 2h).

[0138] Figure 12 and Figure 13 These are schematic diagrams of the AA section of a first measuring feature in another type of measuring structure, taken at a first rotation angle (0°) and a second rotation angle (180°). Figure 12 and Figure 13 As shown, in this embodiment, the cross-section of the first measuring feature is quadrilateral, but its top and bottom edges are not parallel, and... Figure 10 and Figure 11 The structure has different convex directions. Its geometric parameters can be determined by measurement. Let the height of the first measuring feature be h, the length of the base be X0, the angle between one side and the base (in this embodiment, the base is aligned with the horizontal direction) be α, and the angle between the other side and the base be β, satisfying β≤90°-θ, where θ is the electron beam landing angle deviation. Using the above solution process, we can still obtain: delta CD = CD1-CD2 = 2h*tan(θ), theta(θ) = arctan(delta CD / 2h).

[0139] Therefore, for a measurement feature structure whose cross-section is a parallelogram or whose cross-section is a quadrilateral and whose side and base angle β satisfies β≤90°-θ, the functional relationship between the deviation of the first key dimension and the second key dimension and the geometric parameters is the functional relationship between the tangent of the deviation of the electron beam landing angle and the difference between the first key dimension and the second key dimension and the height ratio of the first measurement feature, i.e., theta(θ)= arctan(deltaCD / 2h).

[0140] Example 3:

[0141] Figure 14 and Figure 15 These are schematic diagrams of the AA section of a measurement structure, showing the first measurement feature at a first rotation angle (0°) and a second rotation angle (180°). Figure 14 and Figure 15As shown, in this embodiment, the cross-section of the first measuring feature is quadrilateral, and its top and bottom edges are parallel. Its geometric parameters can be determined through measurement. Let the height of the first measuring feature be h, the length of the bottom edge be X0, the angle between one side and the bottom edge (in this embodiment, the bottom edge is aligned with the horizontal direction) be α, and the angle between the other side and the bottom edge be β. Figure 8 and Figure 9 The example differs in that the included angle β satisfies: β>90°-θ, where θ is the electron beam landing angle deviation.

[0142] Using the above solution process, we can obtain: delta CD = CD1-CD2= (X0+h / tan(α)+h*tan(θ) )-(X0+h / tan(α)-h / tan(β))=h*tan(θ) +h / tan(β);

[0143] Furthermore, we can obtain: arctan(θ) = delta CD / h-1 / tan(β).

[0144] Therefore, for the measurement feature structure of this embodiment, the functional relationship between the deviation of the first key dimension and the second key dimension and the geometric parameters is the tangent of the deviation of the electron beam landing angle, and the functional relationship between the difference between the first key dimension and the second key dimension, the height ratio of the first measurement feature, and the cotangent of the included angle β is arctan(θ)=delta CD / h-1 / tan(β).

[0145] Example 4:

[0146] Figure 16 and Figure 17 These are schematic diagrams of the AA section of a first measuring feature in another type of measuring structure, taken at a first rotation angle (0°) and a second rotation angle (180°). Figure 16 and Figure 17 As shown, in this embodiment, the cross-section of the first measuring feature is quadrilateral, and... Figure 8 and Figure 9 The example differs in that its top and bottom edges are not parallel. Its geometric parameters can be determined by measurement. Let the height of the first measurement feature be h, the length of the bottom edge be X0, the angle between the side edge and the bottom edge (in this embodiment, the bottom edge is aligned with the horizontal direction) be α, and the angle between the other side edge and the bottom edge be β. The angle β satisfies: β > 90° - θ, where θ is the electron beam landing angle deviation.

[0147] At this point, based on geometric relationships, it is found that delta CD is not equal to CD1-CD2= (X0+h / tan(α)+h*tan(θ))-(X0+h / tan(α)-h / tan(β))=h*tan(θ) +h / tan(β). In other words, the deviation between the first and second critical dimensions and the functional relationship of geometric parameters cannot be clearly obtained through a geometric model. That is to say, the above method is not applicable to measurement feature structures where the cross-section of the first measurement feature is quadrilateral, and the angle β between its side and bottom sides satisfies: β>90°-θ, but its top and bottom sides are not parallel. Therefore, when designing measurement features, this type of structure should be avoided. The structures in embodiments 1-3 can be selected to correct the electron beam landing angle.

[0148] Figure 18 This is a schematic diagram of the structure of a semiconductor measurement system provided in one embodiment of this application. Figure 18 As shown, the semiconductor measurement system provided in this embodiment includes at least a sample stage 1810, a scanning electron microscope 1820, and a processor 1830.

[0149] In this embodiment, the sample stage 1810 is used to support and rotate the sample to be tested. By precisely controlling the rotation angle of the sample stage 1810, the sample to be tested can be placed in different spatial orientations, thereby cooperating with the scanning electron microscope 1820 to scan the measurement features on the sample from multiple angles.

[0150] The scanning electron microscope 1820 is used to generate and scan an electron beam. It generates, focuses, and controls a high-energy electron beam, guiding it to scan the sample surface along a pre-defined path. When the electron beam bombards the sample, it generates various signals (such as secondary electrons), which are captured by a detector to form a high-resolution image of the sample surface. In this method, it is not only used for imaging, but its internal scanning coil or dedicated correction coil also acts as an actuator to perform corrections. By changing the excitation current, it adjusts the incident direction of the electron beam, thereby directly correcting deviations in the landing angle.

[0151] The processor 1830 is communicatively connected to the sample stage 1810 and the scanning electron microscope 1820. The processor 1830 is pre-programmed and internally stores instructions for executing the electron beam landing angle correction method described above. When executed, these instructions implement the electron beam landing angle correction method as described in any of the above embodiments. Specifically, it controls the rotation sequence of the sample stage 1810, the scanning operation of the electron beam, and receives measurement data from the scanning electron microscope. Subsequently, it automatically executes all calculation steps, including calculating the deviation of key dimensions, determining the functional relationship based on the characteristic geometric model, retrieving the electron beam landing angle deviation information, and finally generating instructions to adjust the electron beam incident state.

[0152] The processor 1830 can be a central processing unit (CPU), an application specific integrated circuit (ASIC), or a control module that integrates multiple processing units.

[0153] In some embodiments, the program or instructions executed by the processor 1830 are pre-stored in the memory 1840, and the processor 1830 executes them by calling them from the memory.

[0154] The memory 1840 may include volatile memory or non-volatile memory, or it may include both volatile and non-volatile memory. The non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory can be random access memory (RAM), static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct memory bus RAM (DRRAM).

[0155] This application also provides a readable storage medium storing a program or instructions that, when executed by a processor, implement various processes of any embodiment of the electron beam landing angle correction method described above, and achieve the same technical effect. To avoid repetition, these will not be described again here.

[0156] The processor can be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0157] Those skilled in the art will understand that all or part of the functions of the various methods in the above embodiments can be implemented by hardware or by computer programs. When all or part of the functions in the above embodiments are implemented by computer programs, the program can be stored in a computer-readable storage medium, which may include: read-only memory, random access memory, disk, optical disk, hard disk, etc., and the program is executed by a computer to achieve the above functions. For example, the program can be stored in the memory of a device, and when the program in the memory is executed by the processor, all or part of the above functions can be achieved. In addition, when all or part of the functions in the above embodiments are implemented by computer programs, the program can also be stored in a server, another computer, disk, optical disk, flash drive, or external hard drive, etc., and can be downloaded or copied to the memory of a local device, or the system of the local device can be updated. When the program in the memory is executed by the processor, all or part of the functions in the above embodiments can be achieved.

[0158] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art, under the guidance of this application, can make several simple deductions, modifications or substitutions based on the spirit of this application and the scope of protection of the claims without departing from the spirit of this application and the claims. All of these are within the protection scope of this application.

Claims

1. A method for correcting the landing angle of an electron beam, characterized in that, include: When the sample to be tested is at the first rotation angle, the electron beam is controlled to scan the first measurement feature on the sample to be tested in a first preset direction, and the first key dimension of the first measurement feature is obtained according to the scanning result. When the sample to be tested is at the second rotation angle, the electron beam is controlled to scan the first measurement feature in the first preset direction, and the second key dimension of the first measurement feature is obtained according to the scanning result; wherein, the second rotation angle differs from the first rotation angle by 180°; Based on the deviation between the first critical dimension and the second critical dimension and the geometric parameters of the first measurement feature, the first deviation information of the electron beam landing angle is determined; Based on the first deviation information, the incident state of the electron beam is adjusted and iteratively corrected until the deviation between the first critical dimension and the second critical dimension is less than a preset threshold. The step of determining the first deviation information of the electron beam landing angle based on the deviation between the first critical dimension and the second critical dimension and the geometric parameters of the first measurement feature includes: Calculate the deviation between the first critical dimension and the second critical dimension; Based on the geometry of the first measurement feature cross section, a functional relationship corresponding to the geometry is determined; wherein, the functional relationship is used to define the mathematical relationship between the deviation between the first critical dimension and the second critical dimension and the deviation of the electron beam landing angle; The electron beam landing angle deviation is obtained based on the stated functional relationship and the deviation.

2. The method for correcting the electron beam landing angle according to claim 1, characterized in that, The deviation between the first critical dimension and the second critical dimension includes one or more of the difference between the first critical dimension and the second critical dimension, the ratio, and the percentage difference.

3. The method for correcting the electron beam landing angle according to claim 1, characterized in that, The cross-section of the first measuring feature is a parallelogram.

4. The method for correcting the electron beam landing angle according to claim 1, characterized in that, The cross-section of the first measurement feature is quadrilateral, and the angle β between its side and the bottom side satisfies: β≤90°-θ, where θ is the electron beam landing angle deviation.

5. The method for correcting the electron beam landing angle according to claim 3 or 4, characterized in that, The step of determining the functional relationship corresponding to the geometry of the first measured feature cross-section includes: Establish a functional relationship between the tangent of the electron beam landing angle deviation, the difference between the first critical dimension and the second critical dimension, and the height ratio of the first measurement feature.

6. The method for correcting the electron beam landing angle according to claim 1, characterized in that, The cross-section of the first measurement feature is a quadrilateral with the top and bottom sides parallel, and the angle β between its side and bottom sides satisfies: β > 90° - θ, where θ is the electron beam landing angle deviation.

7. The method for correcting the electron beam landing angle according to claim 6, characterized in that, The step of determining the functional relationship corresponding to the geometry of the first measured feature cross-section includes: Establish a functional relationship between the tangent of the electron beam landing angle deviation, the difference between the first and second critical dimensions, the height ratio of the first measurement feature, and the cotangent of the included angle β.

8. The method for correcting the electron beam landing angle according to claim 1, characterized in that, Based on the first deviation information, the incident state of the electron beam is adjusted, including: Based on the first deviation information, adjust the excitation current of the scanning coil or dedicated correction coil in the scanning electron microscope in the X and Y directions.

9. The method for correcting the electron beam landing angle according to claim 1, characterized in that, The first measurement feature is a protruding structure with the sidewalls inclined relative to the sample surface.

10. The method for correcting the electron beam landing angle according to claim 1, characterized in that, Also includes: When the sample to be tested is at the third rotation angle, the electron beam is controlled to scan the second measurement feature on the sample to be tested in the second preset direction, and the third key dimension of the second measurement feature is obtained according to the scanning result; When the sample to be tested is at the fourth rotation angle, the electron beam is controlled to scan the second measurement feature in the second preset direction, and the fourth key dimension of the second measurement feature is obtained according to the scanning result; Based on the deviation between the third and fourth key dimensions and the geometric parameters of the second measurement feature, the second deviation information of the electron beam landing angle is determined; The incident state of the electron beam is adjusted based on the first deviation information and the second deviation information. The second measurement feature has a different spatial orientation than the first measurement feature; The third rotation angle differs from the fourth rotation angle by 180°, and the third rotation angle differs from the first rotation angle by 90°.

11. A semiconductor measurement system, characterized in that, include: The sample stage is used to hold and rotate the sample to be tested. A scanning electron microscope is used to generate and scan electron beams; A processor, communicatively connected to the sample stage and the scanning electron microscope; the processor is configured to perform a method for correcting the electron beam landing angle as described in any one of claims 1 to 10.

12. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer-executable program or instructions, which, when executed by a processor, are used to implement the method for correcting the electron beam landing angle as described in any one of claims 1 to 10.

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