On-line geometric correction method and device for wafer tomography

Abstract

The present application provides an online geometric correction method and device for wafer tomography, the method comprising: collecting a first projection image, a second projection image, and a third projection image of the target feature of the object to be measured at different magnifications, with the line connecting the focus of the ray source and the center of the detector imaging plane perpendicular to the detection surface; calculating a corrected source-object distance and a corrected source-image distance based on the numerical relationship between the imaging parameters and the feature size reflected in the first projection image, the second projection image, and the third projection image; updating a geometric correction parameter group based on the corrected source-object distance and the corrected source-image distance, and updating the motion trajectory of the wafer tomography based on the geometric correction parameter group to obtain a corresponding motion trajectory parameter group, and saving the geometric correction parameter group and motion trajectory parameter group for wafer tomography. This method solves the problem of geometric correction parameter distortion caused by focus drift in online tomography, and is low-cost.

Description

Technical Field

[0001] The present application relates to the technical field of wafer three-dimensional imaging, and in particular to an online geometric correction method and device for wafer tomography, and also to an electronic device and storage medium for executing the online geometric correction method for wafer tomography. Background Art

[0002] Wafer laminography is a technology used to perform three-dimensional imaging of wafer internal structures. Achieving high-precision 3D reconstruction using laminography places stringent requirements on geometric correction. During the imaging process, geometric distortion can occur due to various factors, such as sample placement. Correcting this distortion through geometric correction yields more accurate images. Existing geometric correction methods include phantom calibration and offline iterative calibration. Geometric correction using a specific phantom requires high accuracy, and deviations in phantom parameters can lead to errors in the calculation of the center of rotation. Iterative calibration, on the other hand, requires estimating the center of rotation, reconstructing the image based on the estimated center of rotation, and repeatedly adjusting the estimated center of rotation until the geometric distortion of the reconstructed image is minimized. This method is complex and time-consuming. Furthermore, during online wafer laminography, inaccurate rotation centers can cause offsets in the projection of the object under test on the detector imaging plane, resulting in artifacts and distortion in the 3D reconstruction. Existing phantom calibration and iterative calibration methods are unable to address the parameter distortion caused by drift in the focus position of the radiation source during online laminography. Summary of the Invention

[0003] In view of this, the embodiments of the present application provide an online geometric correction method and device for wafer tomography, as well as an electronic device and storage medium for executing the online geometric correction method for wafer tomography, which can solve the parameter distortion problem caused by the drift of the focus position of the radiation source in existing online tomography.

[0004] A first aspect of an embodiment of the present application provides an online geometric correction method for wafer tomography, comprising: collecting a first projection image, a second projection image, and a third projection image of a target feature of an object to be measured at different magnifications when a line connecting the focus of a ray source and the center of an imaging plane of a detector is perpendicular to a detection surface; calculating a corrected source-object distance and a corrected source-image distance based on a numerical relationship between imaging parameters and feature sizes reflected in the first projection image, the second projection image, and the third projection image, wherein the imaging parameters include the source-object distance and the source-image distance, and the feature sizes include the actual size and the projected size of the target feature of the object to be measured; updating a geometric correction parameter group based on the corrected source-object distance and the corrected source-image distance, and updating a motion trajectory of wafer tomography based on the geometric correction parameter group to obtain a corresponding motion trajectory parameter group, and saving the geometric correction parameter group and the motion trajectory parameter group for wafer tomography.

[0005] In one possible implementation, the step of acquiring a first projection image, a second projection image, and a third projection image of the target feature of the object to be measured at different magnifications when the line connecting the focus of the ray source and the center of the detector imaging plane is perpendicular to the detection surface includes: adjusting the position of the object stage toward the side of the ray source along the direction of the line connecting the focus of the ray source and the center of the detector imaging plane to obtain different magnifications of the target feature of the object to be measured; and / or adjusting the position of the detector toward the side of the ray source along the direction of the line connecting the focus of the ray source and the center of the detector imaging plane to obtain different magnifications of the target feature of the object to be measured; and / or adjusting the position of the ray source toward the side of the detector along the direction of the line connecting the focus of the ray source and the center of the detector imaging plane to obtain different magnifications of the target feature of the object to be measured.

[0006] In one possible implementation, the step of calculating the corrected source-object distance and the corrected source-image distance based on the numerical relationship between the imaging parameters and the characteristic dimensions reflected by each of the first projection image, the second projection image, and the third projection image includes: calculating based on the numerical relationship between the imaging parameters and the characteristic dimensions reflected in the first projection image in combination with the numerical relationship between the imaging parameters and the characteristic dimensions reflected in the second projection image to obtain the corrected source-object distance; and calculating based on the corrected source-object distance in combination with the numerical relationship between the imaging parameters and the characteristic dimensions reflected in the third projection image to obtain the corrected source-image distance.

[0007] In one possible implementation, after the step of calculating the corrected source-object distance and the corrected source-image distance based on the numerical relationship between the imaging parameters and the characteristic dimensions reflected by the first projection image, the second projection image, and the third projection image, the method further includes: adjusting the detector position or the ray source position along the direction of the line connecting the ray source focus and the center of the detector imaging plane, and acquiring a fourth projection image; based on the fourth projection image, verifying the corrected source-object distance according to a preset verification formula to determine whether the corrected source-object distance and the corrected source-image distance meet a preset accuracy condition; if the corrected source-object distance and the corrected source-image distance do not meet the preset accuracy condition, recalculating the corrected source-object distance according to a preset source-object distance calculation formula and recalculating the corrected source-image distance based on the recalculated source-object distance; wherein the preset verification formula is: ; SOD is the corrected source-object distance, SDD is the corrected source-image distance; ΔX4 is the projection size of the target feature of the object to be measured on the detector, δx is the actual size of the target feature of the object to be measured, and z4 is the adjustment distance of the detector position or the ray source position; the preset source-object distance calculation formula is SOD = z4+(SDD-z4)*δx / ΔX4.

[0008] In one possible implementation, before the step of collecting the first projection image, the second projection image, and the third projection image of the target feature of the object to be measured at different magnifications when the line connecting the focus of the ray source and the center of the imaging plane of the detector is perpendicular to the detection surface, the step further includes: placing the object to be measured on the stage, performing target detection on the object to be measured, and determining the target feature of the object to be measured; collecting the fifth projection image and the sixth projection image of the target feature of the object to be measured at different magnifications; adjusting the positions of the stage and the detector in the plane direction according to the fifth projection image and the sixth projection image until the projection position of the target feature of the object to be measured on the detector remains unchanged and coincides with the center of the imaging plane of the detector, so that the line connecting the focus of the ray source and the center of the imaging plane of the detector is perpendicular to the detection surface, wherein the plane direction includes the longitudinal axis direction and the transverse axis direction of the object to be measured.

[0009] In one possible implementation, the steps of placing the object to be tested on a stage, performing target detection on the object to be tested, and determining the target characteristics of the object to be tested include: performing target detection on the object to be tested by moving the stage in a direction perpendicular to the plane of the stage to determine the target characteristics of the object to be tested; or performing target detection on the object to be tested by performing dynamic perspective on the object to be tested to determine the target characteristics of the object to be tested.

[0010] In one possible implementation, the step of updating the motion trajectory of wafer tomography according to the geometric correction parameter group to obtain the corresponding motion trajectory parameter group includes: keeping the position of the ray source unchanged, controlling the stage and the detector to move stepwise to the target position along the transverse axis of the object to be measured, and controlling the detector to deflect to a first target angle along the longitudinal axis of the object to be measured, so as to obtain the corresponding motion trajectory parameter group; or keeping the position of the ray source unchanged, controlling the stage and the detector to move stepwise to the target position along the longitudinal axis of the object to be measured, and controlling the detector to deflect to a second target angle along the transverse axis of the object to be measured, so as to obtain the corresponding motion trajectory parameter group; or keeping the position of the ray source unchanged, controlling the stage and the detector to move stepwise to the target position along the transverse axis of the object to be measured and the longitudinal axis of the object to be measured respectively, and controlling the detector to deflect to the first target angle along the longitudinal axis of the object to be measured and to the second target angle along the transverse axis of the object to be measured, so as to obtain the corresponding motion trajectory parameter group.

[0011] A second aspect of an embodiment of the present application provides an online geometric correction device for wafer tomography, comprising: an acquisition module for acquiring a first projection image, a second projection image, and a third projection image of a target feature of an object to be measured at different magnifications when a line connecting the focus of a ray source and the center of an imaging plane of a detector is perpendicular to a detection surface; a calculation module for calculating a corrected source-object distance and a corrected source-image distance based on a numerical relationship between imaging parameters and feature sizes reflected in the first projection image, the second projection image, and the third projection image, wherein the imaging parameters include the source-object distance and the source-image distance, and the feature sizes include the actual size and the projection size of the target feature of the object to be measured; a correction module for updating a geometric correction parameter group based on the corrected source-object distance and the corrected source-image distance, and updating a motion trajectory of wafer tomography based on the geometric correction parameter group, obtaining a corresponding motion trajectory parameter group, and saving the geometric correction parameter group and the motion trajectory parameter group for wafer tomography.

[0012] A third aspect of an embodiment of the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the electronic device. When the processor executes the computer program, the steps of the online geometric correction method for wafer tomography provided in the first aspect are implemented.

[0013] A fourth aspect of an embodiment of the present application provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the steps of the online geometric correction method for wafer tomography provided in the first aspect are implemented.

[0014] A fifth aspect of the embodiments of the present application provides a computer program product. When the computer program product is run on an electronic device, the electronic device implements the steps of the online geometric correction method for wafer tomography provided in the first aspect.

[0015] The embodiments of the present application provide an online geometric correction method and apparatus for wafer tomography, as well as an electronic device and a storage medium for executing the online geometric correction method for wafer tomography, which have the following beneficial effects:

[0016] The present application collects the first projection image, the second projection image and the third projection image of the target feature of the object to be measured at different magnifications under the condition that the line connecting the focus of the ray source and the center of the imaging plane of the detector is perpendicular to the detection surface; calculates the corrected source-object distance and the corrected source-image distance based on the numerical relationship between the imaging parameters and the feature size reflected by the first projection image, the second projection image and the third projection image; updates the geometric correction parameter group based on the corrected source-object distance and the corrected source-image distance, and updates the motion trajectory of the wafer tomography based on the geometric correction parameter group to obtain the corresponding motion trajectory parameter group, and saves the geometric correction parameter group and the motion trajectory parameter group for wafer tomography. This method solves the problem of geometric correction parameter distortion caused by focus drift in online tomography, and at the same time reduces the requirements for high-precision position movement and position sensing, greatly reducing the system cost while ensuring the accuracy and quality of three-dimensional image reconstruction. It is simple and efficient to operate, has strong repeatability, strong applicability, and is insensitive to noise and jitter. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 A flowchart for implementing an online geometric correction method for wafer tomography provided in an embodiment of the present application;

[0019] Figure 2 A flowchart for calculating the corrected source-object distance and the corrected source-image distance in the online geometric correction method for wafer tomography provided in an embodiment of the present application;

[0020] Figure 3 A flowchart for implementing the calibration of the corrected source-object distance in the online geometric correction method for wafer tomography provided in an embodiment of the present application;

[0021] Figure 4A flowchart for implementing the adjustment of the line connecting the focus of the radiation source and the center of the detector imaging plane to be perpendicular to the detection surface in the online geometric correction method for wafer tomography provided in an embodiment of the present application;

[0022] Figure 5 Schematic diagram of motion trajectories of three types of wafer tomography in the online geometric correction method for wafer tomography provided in an embodiment of the present application;

[0023] Figure 6 A basic structural block diagram of an online geometric correction device for wafer tomography provided in an embodiment of the present application;

[0024] Figure 7 This is a basic structural block diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] In the following description, specific details such as specific system structures and techniques are provided for purposes of illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obscuring the description of the present application with unnecessary detail.

[0026] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections thereof.

[0027] It will also be understood that the term "and / or" used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0028] As used in this specification and the appended claims, the term "if" can be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0029] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0030] References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of the present application include a particular feature, structure, or characteristic described in conjunction with that embodiment. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized. "Multiple" means "two or more."

[0031] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0032] The existing geometric correction process for X-ray tomography is cumbersome and has the following disadvantages: traditional geometric correction methods require high accuracy of the system model and high precision of the scanning angle and position, which can easily cause reconstruction artifacts; image iterative correction methods are relatively complex and multiple iterations are time-consuming; they require reliance on a phantom; offline correction is sensitive to noise and jitter, making it less applicable; correction requires appropriate exposure parameters, which places many preconditions on the correction; interference factors such as focus drift and machine jitter require multiple offline phantom corrections, increasing time costs and difficulty; the position of the correction phantom is inconsistent with the position of the actual sample, which can easily lead to distortion of the correction parameters. To address the above shortcomings, the present application aims to provide an online geometric correction method and device for wafer tomography. Through online geometric correction, the calculated coordinates are adjusted in real time according to interference such as noise and jitter, with strong applicability and no need for a phantom. In addition, online calculation can save time and cost, and is not affected by exposure parameters, and there is no interference due to phantom accuracy. Even if interference such as focus drift and machine jitter occurs, the motion trajectory can be adjusted through real-time online geometric correction to promptly eliminate artifacts and geometric distortion caused by reconstruction.

[0033] In some embodiments of this application, please refer to Figure 1 , Figure 1 This is a flow chart for implementing an online geometric correction method for wafer tomography provided in an embodiment of the present application. Figure 1 As shown, it may specifically include steps S11 to S13.

[0034] S11: When the line connecting the focus of the ray source and the center of the imaging plane of the detector is perpendicular to the detection surface, a first projection image, a second projection image, and a third projection image of the target feature of the object to be measured at different magnifications are collected.

[0035] In this embodiment, based on the requirements of 3D reconstruction algorithms, such as the Feldkamp-Davis-Kress (FDK) algorithm, the precise coordinates of the projection point of the radiation source's focal point on the detector's imaging plane must be known. In practical imaging systems, errors in the projection point can affect the accuracy of the reconstructed image, resulting in artifacts, and compromising image resolution and effective detail detection. In a specific embodiment, the position of the radiation source's focal point can be tracked online, and the position of the focal point relative to the center of the detector's imaging plane can be adjusted based on changes in the projection position of the object under test on the detector's imaging plane. This ensures that the line connecting the radiation source's focal point and the center of the detector's imaging plane remains perpendicular to the detection surface. This ensures that the rotation center used for 3D reconstruction remains unchanged, ensuring the quality of the captured image and increasing the robustness of the reconstructed image quality. In this embodiment, the magnification factor is equal to the ratio of the source-object distance to the source-image distance. When capturing projection images of a target feature under test, the imaging parameters can be varied several times to obtain first, second, and third projection images of the target feature under test at different magnification factors. Among them, the imaging parameters include source-object distance and source-image distance. The source-object distance is expressed as the distance between the center of the ray source focus and the object to be measured, and the source-image distance is expressed as the distance between the center of the ray source focus and the center of the detector imaging plane.

[0036] S12: Calculate the corrected source-object distance and the corrected source-image distance based on the numerical relationship between the imaging parameters and the characteristic dimensions reflected by the first projection image, the second projection image, and the third projection image, wherein the imaging parameters include the source-object distance and the source-image distance, and the characteristic dimensions include the actual dimensions and the projected dimensions of the target features of the object to be measured.

[0037] In this embodiment, the first projection image, the second projection image, and the third projection image are projection images at different magnifications, and the imaging parameters and characteristic dimensions reflected by each are different in numerical value. The imaging parameters include the source-object distance and the source-image distance, and the characteristic dimensions include the actual size and the projected size of the target feature of the object to be measured. The numerical relationship between the imaging parameters and the characteristic dimensions is specifically expressed as the ratio of the source-object distance to the source-image distance being equal to the ratio of the actual size to the projected size. Based on the first projection image, the second projection image, and the third projection image, three sets of numerical relationship formulas can be obtained correspondingly, in which the ratio of the source-object distance to the source-image distance is equal to the ratio of the actual size to the projected size. Based on the three sets of numerical relationship formulas, a joint calculation can be performed to obtain a more accurate source-object distance and source-image distance as the corrected source-object distance and the corrected source-image distance.

[0038] S13: updating a geometric correction parameter group according to the corrected source-object distance and the corrected source-image distance, and updating a motion trajectory of wafer tomography according to the geometric correction parameter group, obtaining a corresponding motion trajectory parameter group, and saving the geometric correction parameter group and the motion trajectory parameter group for wafer tomography.

[0039] In the present embodiment, the geometric correction parameter group includes source-object distance, source-image distance, scanning multi-angle range, number of projections, deflection angle, starting angle, horizontal axis coordinate and vertical axis coordinate of the starting stage center, horizontal axis coordinate and vertical axis coordinate of the detector center position, etc. Except for the two parameters of source-object distance and source-image distance, the remaining parameters are preset fixed parameters. According to the corrected source-object distance and the corrected source-image distance, updating the geometric correction parameter group mainly updates the two parameters of source-object distance and source-image distance in the geometric correction parameter group to the corrected source-object distance and the corrected source-image distance, and the remaining parameters remain unchanged. In the specific implementation manner of this embodiment, the multiple projection angles of the motion trajectory can be determined by the parameters such as scanning multi-angle range, number of projections, deflection angle, starting angle, etc. in the geometric correction parameter group. When updating the motion trajectory of wafer tomography, the motion trajectory parameters of the motion trajectory under each projection angle condition can be output to form a motion trajectory parameter group. The motion trajectory parameter set includes parameters such as the horizontal and vertical coordinates of the stage center, the horizontal and vertical coordinates of the detector center, the detector deflection angle along the vertical axis, and the detector deflection angle along the horizontal axis under each projection angle condition. After the geometric parameter set and motion trajectory parameter set are updated, they are saved and used in the 3D reconstruction process of wafer tomography.

[0040] From the above, it can be seen that the online geometric correction method for wafer tomography provided in the embodiment of the present application collects projection images of different magnifications when the line connecting the focus of the ray source and the center of the detector imaging plane is perpendicular to the detection surface. Based on the numerical relationship between the imaging parameters and the characteristic dimensions reflected by the projection images of different magnifications, the corrected source-object distance and the corrected source-image distance are calculated, and then the geometric correction parameter group is updated according to the corrected source-object distance and the corrected source-image distance, and the motion trajectory of the wafer tomography is updated according to the geometric correction parameter group to obtain the corresponding motion trajectory parameter group, and the generated geometric correction parameter group and the obtained motion trajectory parameter group are saved for subsequent three-dimensional reconstruction during wafer tomography. This method realizes online tracking of the center position of the focus of the ray source, adjusts the position of the focus center relative to the center of the detector imaging plane according to the change of the projection position of the object to be measured on the detector imaging plane, ensures that the rotation center used for 3D reconstruction remains unchanged, ensures the quality of the acquired image, and increases the robustness of the reconstructed image quality; the source-object distance and the source-image distance can be accurately obtained by changing the imaging parameters several times. The operation is simple and efficient, with strong repeatability and applicability, and is insensitive to noise and jitter. It not only solves the problem that conventional tomography cannot handle the distortion of geometric correction parameters caused by focus drift, but also reduces the requirements for high-precision position movement and position sensing, greatly reducing the system cost while ensuring the accuracy and quality of 3D image reconstruction.

[0041] In some embodiments of the present application, when acquiring a projection image of a target feature of an object to be measured, different magnification factors of the target feature to be measured can be obtained by adjusting the relative position of any one of the radiation source, the stage, or the detector in the direction of the line connecting the radiation source focal point and the center of the detector imaging plane. For example, the position of the stage can be adjusted toward the radiation source along the direction connecting the radiation source focal point and the center of the detector imaging plane to shorten the distance between the radiation source and the stage, i.e., shorten the source-object distance, thereby obtaining different magnification factors of the target feature to be measured. For example, the position of the detector can also be adjusted toward the radiation source along the direction connecting the radiation source focal point and the center of the detector imaging plane to shorten the distance between the radiation source and the detector, i.e., shorten the source-image distance, thereby obtaining different magnification factors of the target feature to be measured. For example, the position of the radiation source can also be adjusted toward the detector along the direction connecting the radiation source focal point and the center of the detector imaging plane to shorten the distance between the radiation source and the stage and the distance between the radiation source and the detector, i.e., shorten both the source-object distance and the source-image distance, thereby obtaining different magnification factors of the target feature to be measured.

[0042] In some embodiments of this application, please refer to Figure 2 , Figure 2This is a flowchart for calculating the corrected source-object distance and the corrected source-image distance in the online geometric correction method for wafer tomography provided in an embodiment of the present application. Figure 2 As shown, it may specifically include step S21 to step S22.

[0043] S21: performing calculation based on the numerical relationship between the imaging parameters and the characteristic size reflected in the first projection image and the numerical relationship between the imaging parameters and the characteristic size reflected in the second projection image to obtain a corrected source-object distance;

[0044] S22: Calculate the corrected source-object distance based on the corrected source-object distance in combination with the numerical relationship between the imaging parameters and the characteristic size reflected in the second projection image and the numerical relationship between the imaging parameters and the characteristic size reflected in the third projection image to obtain the corrected source-image distance.

[0045] In this embodiment, the first projection image may be a projection image directly acquired after determining that the line connecting the focus of the radiation source and the center of the detector imaging plane is perpendicular to the detection surface, without adjusting the relative positions of the radiation source, stage, and detector. The second projection image may be a projection image acquired after acquiring the first projection image and then adjusting the position of the stage toward the radiation source along the line connecting the focus of the radiation source and the center of the detector imaging plane, thereby shortening the relative distance between the radiation source and the stage by z1. The third projection image may be a projection image acquired after acquiring the second projection image and then adjusting the position of the detector toward the radiation source along the line connecting the focus of the radiation source and the center of the detector imaging plane, thereby shortening the relative distance between the radiation source and the detector by z2.

[0046] Because the first, second, and third projection images project the same target feature, the actual size of the target feature reflected in each of these three projection images is δx. Because the magnification factors of the first, second, and third projection images are different, the projected sizes of the target feature reflected in these three projection images are also different: ΔX, ΔX1, and ΔX2, respectively. Assuming the source-object distance (SOD) and source-image distance (SDD) reflected in the first projection image are SOD and SDD, then the source-object distance (SOD - z1) and source-image distance (SDD) reflected in the second projection image are SOD - z1 and SDD, respectively. The source-object distance (SOD - z1) and source-image distance (SDD - z2) reflected in the third projection image are SOD - z1 and SDD - z2, respectively.

[0047] According to the first projection image, the following numerical relationship formula 1 can be obtained:

[0048]

[0049] According to the second projection image, the following numerical relationship formula 2 can be obtained:

[0050]

[0051] According to the third projection image, the following numerical relationship formula 3 can be obtained:

[0052]

[0053] At this point, by combining numerical equations 1 and 2 to correct the source-object distance in the numerical equations, a more accurate source-object distance can be obtained as the corrected source-object distance. After obtaining the corrected source-object distance, the corrected source-object distance is substituted into numerical equations 2 and 3, and by combining numerical equations 2 and 3 to correct the source-image distance in the numerical equations, a more accurate source-image distance can be obtained as the corrected source-image distance.

[0054] In one specific embodiment, the third projection image can be acquired after acquiring the second projection image by adjusting the position of the radiation source toward the detector along the line connecting the radiation source focal point and the center of the detector imaging plane, thereby shortening the relative distances between the radiation source, the stage, and the detector by z3. Accordingly, the projection size reflected by the third projection image is ΔX3, the source-object distance is SOD - z1 - z3, and the source-image distance is SDD - z3. Based on the third projection image, the following numerical relationship equation (4) can be obtained:

[0055]

[0056] At this time, by substituting the corrected source-object distance into numerical relationship equation 2 and numerical relationship equation 4, and combining numerical relationship equation 2 and numerical relationship equation 4 to correct the source-image distance in the numerical relationship equation, a more accurate source-image distance can be obtained as the corrected source-image distance.

[0057] In one specific embodiment, the second projection image can be acquired after acquiring the first projection image by adjusting the position of the radiation source toward the detector along the line connecting the radiation source focal point and the center of the detector imaging plane, thereby shortening the relative distance between the radiation source and the stage by z5. Accordingly, the projection size reflected by the second projection image is ΔX5, the source-object distance is SOD - z5, and the source-image distance is SDD - z5. Based on the second projection image, the following numerical relationship equation 5 can be obtained:

[0058]

[0059] At this time, by combining the numerical relationship formula 1 and the numerical relationship formula 5 and performing a correction calculation on the source-object distance in the numerical relationship formula, a more accurate source-object distance can be obtained as the corrected source-object distance.

[0060] In some embodiments of this application, please refer to Figure 3 , Figure 3 This is a flow chart for verifying the corrected source-object distance in the online geometric correction method for wafer tomography provided in an embodiment of the present application. Figure 3 As shown, it may specifically include steps S31 to S33.

[0061] S31: After adjusting the position of the detector or the position of the ray source along the direction of the line connecting the ray source focus and the center of the detector imaging plane, a fourth projection image is acquired;

[0062] S32: Based on the fourth projection image, calibrate the corrected source-object distance according to a preset calibration formula to determine whether the corrected source-object distance and the corrected source-image distance meet a preset accuracy condition;

[0063] S33: If the corrected source-object distance and the corrected source-image distance do not meet the preset accuracy condition, recalculating the corrected source-object distance according to a preset source-object distance calculation formula and recalculating the corrected source-image distance based on the recalculated source-object distance;

[0064] The preset verification formula is: ; SOD is the corrected source-object distance, SDD is the corrected source-image distance; ΔX4 is the projection size of the target feature of the object to be measured on the detector, δx is the actual size of the target feature of the object to be measured, and z4 is the adjustment distance of the detector position or the ray source position; the preset source-object distance calculation formula is SOD = z4+(SDD-z4)*δx / ΔX4.

[0065] In this embodiment, since the accuracy requirement for the source-object distance value in the wafer tomography process is very high, which can reach the level of hundreds of microns, and considering that there may be calculation errors when extracting image target features during online geometric correction and errors caused by inaccurate reading of the value of the relative distance z between the ray source, the stage and the detector, the calculated corrected source-object distance can be further verified to ensure the accuracy of the corrected source-object distance. In a specific embodiment, after calculating the corrected source-object distance and the corrected source-image distance, the position of the detector can be adjusted toward the side of the ray source along the direction of the line connecting the ray source focus and the center of the detector imaging plane to shorten the relative distance between the ray source and the detector by z4, and then a fourth projection image is acquired. At this time, the projection size of the target feature of the object to be measured reflected by the fourth projection image on the detector is ΔX4. The corrected source-object distance is verified according to the following verification formula:

[0066]

[0067] Substitute the corrected source-object distance and the corrected source-image distance into the above verification formula for verification to determine whether the formula is valid. If the formula is valid, it is considered that the corrected source-object distance and the corrected source-image distance meet the preset accuracy conditions. If the formula is not valid, it is considered that the corrected source-object distance and the corrected source-image distance do not meet the preset accuracy conditions. In this case, the corrected source-object distance needs to be recalculated. Specifically, the corrected source-object distance can be recalculated using the following source-object distance calculation formula:

[0068] SOD = z4+(SDD-z4)*δx / ΔX4.

[0069] Furthermore, after verification, if the corrected source-object distance has been recalculated, the recalculated source-object distance is used as the latest corrected source-object distance to be calculated in conjunction with the numerical relationship between the imaging parameters and the characteristic dimensions reflected in the second projection image and the numerical relationship between the imaging parameters and the characteristic dimensions reflected in the third projection image, thereby recalculating the corrected source-image distance.

[0070] In some embodiments of this application, please refer to Figure 4 , Figure 4 This is a flowchart for implementing the method for online geometric correction of wafer tomography provided in an embodiment of the present application to adjust the line connecting the focus of the ray source and the center of the detector imaging plane to be perpendicular to the detection surface. Figure 4 As shown, it may specifically include steps S41 to S43.

[0071] S41: placing the object to be tested on a stage, performing target detection on the object to be tested, and determining target features of the object to be tested;

[0072] S42: Acquire a fifth projection image and a sixth projection image of the target feature of the object to be measured at different magnifications;

[0073] S43: Adjust the positions of the stage and the detector in the plane direction according to the fifth projection image and the sixth projection image until the projection position of the target feature of the object to be measured on the detector remains unchanged and coincides with the center of the imaging plane of the detector, so that the line connecting the focus of the ray source and the center of the imaging plane of the detector is perpendicular to the detection surface, wherein the plane direction includes the longitudinal axis direction and the transverse axis direction of the object to be measured.

[0074] A wafer tomography system typically consists of an X-ray source, a detector, and a stage. The ideal geometry for wafer tomography is that the X-ray beam emitted from the source's focal point passes through the center of rotation, and the line connecting the source's focal point, the center of the target feature on the stage, and the center of the detector's imaging plane is always perpendicular to the detector's imaging plane. In practical wafer tomography systems, the source and detector are offset in various directions. This offset in the source and stage translates into an offset in the projected position on the detector's imaging plane. To capture sufficient detail on the wafer during wafer tomography, the magnification used during imaging is typically several hundred, sometimes even several thousand. However, the higher the magnification, the more demanding it is to suppress source focus drift and the greater the sensitivity to even the smallest changes in source focus drift. At sufficiently high magnifications, geometric correction parameters become ineffective, affecting final image quality. When the X-ray source is working, a large number of electrons emitted from the cathode bombard the surface of the anode target and continuously generate heat. The surface of the target undergoes slight deformation due to thermal expansion and contraction, which causes the effective focus position to drift. This drift phenomenon is inherent. The existing methods of cooling the X-ray source by adding air cooling, liquid cooling, etc. and controlling the movement of the precision submicron control console to suppress the focus offset of the X-ray source are expensive in hardware, complex to control, and cannot be completely eradicated.

[0075] In this embodiment, when using a wafer tomography system to perform wafer tomography on an object to be tested, the wafer tomography system can be pre-calibrated first, and the line connecting the focus of the radiation source and the center of the detector imaging plane in the wafer tomography system can be adjusted to be perpendicular to the detection surface. Specifically, it is assumed that the Y axis is the longitudinal center axis of the object to be tested, the X axis is the transverse center axis of the object to be tested, and the Z axis is the normal direction of the detector imaging plane, and the Z axis is perpendicular to the X axis and the Y axis respectively. The object to be tested (i.e., the wafer) is transferred to the target position on the stage and fixed on the stage. Then, the radiation source, stage, and detector in the wafer tomography system are moved to a preset position. At this time, in principle, the projection coordinates of the center of the radiation source focus on the detector imaging plane completely coincide with the center of the detector imaging plane. However, due to errors caused by various factors such as the placement of the object to be tested, the projection coordinates of the center of the radiation source focus on the detector imaging plane do not coincide with the center of the detector imaging plane. In this embodiment, by moving the stage along the X-axis and Y-axis directions, high-frame-rate target detection is performed on the object to be tested, and an area with obvious features in the object to be tested is found, and the area is determined as the target feature of the object to be tested. After determining the target feature of the object to be tested, the fifth projection image is directly acquired under the current imaging parameter configuration of the wafer tomography imaging system, and then, after moving the stage position along the Z-axis direction, the sixth projection image of the target feature of the object to be tested is acquired. Furthermore, the position of the stage and the detector in the planar direction is adjusted according to the fifth projection image and the sixth projection image. In a specific embodiment, when adjusting the position of the stage in the planar direction, the projection positions of the target features of the object to be tested in the fifth projection image and the sixth projection image can be specifically compared. If the projection position of the target feature of the object to be measured in the two projection images changes in the X-axis direction, the position of the stage in the X-axis direction is adjusted and a new projection image is captured as the sixth projection image, which is compared with the fifth projection image until the projection position of the target feature of the object to be measured does not change in the X-axis direction. At this time, the adjustment of the stage position in the X-axis direction is stopped and the current X-axis coordinate of the stage is saved. If the projection position of the target feature of the object to be measured in the two projection images changes in the Y-axis direction, the position of the stage in the Y-axis direction is adjusted and a new projection image is captured as the updated sixth projection image, which is compared with the fifth projection image until the projection position of the target feature of the object to be measured does not change in the Y-axis direction. At this time, the adjustment of the stage position in the Y-axis direction is stopped and the current Y-axis coordinate of the stage is saved. In this embodiment, the judgment standard for whether the projection position has changed can be set as: the absolute value of the coordinate of the position difference is less than or equal to 1 pixel * pixel pitch.After adjusting the position of the stage in the plane direction, fix the ray source and the stage and update the sixth projection image. According to the updated sixth projection image, move the position of the detector in the X-axis direction so that the projection position of the target feature of the object to be measured in the X-axis direction is located at the center of the detector imaging plane in the X-axis direction, and move the position of the detector in the Y-axis direction so that the projection position of the target feature of the object to be measured in the Y-axis direction is located at the center of the detector imaging plane in the Y-axis direction. Save the X-axis coordinate and Y-axis coordinate of the detector at this time, and the adjustment of the detector in the plane direction is completed. After adjusting the position of the stage and the detector in the plane direction, the projection position of the target feature of the object to be measured on the detector can be made to coincide with the center of the detector imaging plane, so that the line connecting the focus of the ray source and the center of the detector imaging plane is perpendicular to the detection surface. It can be understood that the plane direction is the X-axis direction and the Y-axis direction.

[0076] In a specific embodiment, the sixth projection image may also be acquired by moving the position of the ray source in the Z-axis direction.

[0077] In a specific embodiment, after the radiation source, stage, and detector in the wafer tomography system are moved to preset positions, a level ruler is used to adjust the horizontal flatness of the stage in the X and Y directions at zero position, and an acquisition level ruler is used to adjust the horizontal flatness of the detector in the X and Y directions at zero position to improve the accuracy of geometric correction.

[0078] In some embodiments of the present application, when determining the target features of the object to be tested by performing target detection on the object to be tested, it can be specifically to find the wafer Notch, and by imaging the Notch, extracting the orientation and position of the Notch, the wafer center can be quickly and preliminarily located. Among them, Notch is a physical incision used to mark the direction of the wafer, usually a V-shaped or U-shaped groove, located at the bottom of the edge of the silicon wafer, with accurate position and easy for the machine to read. In order to quickly find the edge of the wafer, a smaller magnification can be set first, such as 5-50 times, until the edge of the wafer is detected, and then the wafer edge is binarized to obtain a fitting circular curve function. The obtained center coordinates are the wafer center coordinates, and then the wafer center is moved to the center of the detector imaging area. In addition to the wafer Notch, the target features of the object to be tested can also be a stripe, multiple stripes, triangles, circles, wafer cutting path gaps or other shapes on the wafer. The target detection method includes performing edge detection, threshold segmentation, contour acquisition and other image processing methods on the projected image to obtain the contour end coordinates of the projected image. In this embodiment, the shape and grayscale value of the same target feature remain unchanged under different magnifications and the same acquisition angle; only the size changes proportionally with the magnification. This characteristic allows for rapid identification of the target feature by statically capturing the projected image while moving the stage perpendicular to its plane. It should be understood that the direction perpendicular to the stage's plane is the Z-axis. In addition to static capture, in this embodiment, dynamic perspective viewing of the target feature can also be used to rapidly identify the target feature. The motion trajectory of the target feature is also clearly visible during the multi-frame acquisition process of dynamic perspective viewing.

[0079] In some embodiments of the present application, the motion trajectory of the wafer tomography can be any one of a linear trajectory moving along the X-axis direction, a linear trajectory moving along the Y-axis direction, and a circular trajectory. Figure 5 As shown, Figure 5 Schematic diagram of the motion trajectories of three types of wafer tomography in the online geometric correction method of wafer tomography provided in an embodiment of the present application.

[0080] When updating the motion trajectory of wafer tomography according to the linear trajectory moving along the X-axis, specifically: keep the position of the ray source unchanged, control the stage and the detector to move stepwise to the target position along the horizontal axis of the object to be measured, and control the detector to deflect to the first target angle along the vertical axis of the object to be measured, so as to obtain the corresponding motion trajectory parameter group. In this embodiment, according to the parameters such as the scanning multi-angle range, the number of projections, the deflection angle, and the starting angle in the geometric parameter group, multiple projection angles of the motion trajectory and their corresponding multiple step target positions can be pre-set. When updating the motion trajectory of wafer tomography, such as Figure 5As shown in (a), the stage and detector can be moved step by step to each step target position according to the preset step target position and sequence at each projection angle, and the horizontal axis coordinate of the stage center (i.e., X-axis coordinate), the horizontal axis coordinate of the detector center position (i.e., X-axis coordinate), and the deflection angle of the detector along the vertical axis (i.e., Y-axis) corresponding to each step target position at each projection angle are output as motion trajectory parameters to form a motion trajectory parameter group. It should be noted that Figure 5 In (a), P is the projection position of the target feature on the object to be measured, and (u, v) are the coordinates of the projection position. For example, assuming the geometric parameter group sets a multi-angle scanning range of 80°, 36 projections, and a starting angle of -40°, then 36 projection angles are obtained, each between -40° and 40°, corresponding to 36 stepping target positions. When the wafer tomography motion trajectory is updated according to a linear trajectory moving along the X-axis, 36 sets of motion trajectory parameter groups are obtained, including the horizontal axis coordinates of the stage center, the horizontal axis coordinates of the detector center position, and the detector deflection angle along the vertical axis.

[0081] When updating the motion trajectory of wafer tomography according to the linear trajectory moving along the Y-axis, specifically: keep the position of the ray source unchanged, control the stage and the detector to move stepwise to the target position along the longitudinal axis of the object to be measured, and control the detector to deflect to a second target angle along the transverse axis of the object to be measured, so as to obtain the corresponding motion trajectory parameter group. In this embodiment, according to the parameters such as the scanning multi-angle range, the number of projections, the deflection angle, and the starting angle in the geometric parameter group, multiple projection angles of the motion trajectory and their corresponding multiple step target positions can be pre-set. When updating the motion trajectory of wafer tomography, such as Figure 5 As shown in (b), the stage and detector can be moved step by step to each step target position according to the preset step target position and sequence at each projection angle, and the vertical axis coordinate (i.e., Y axis coordinate) of the stage center, the vertical axis coordinate (i.e., Y axis coordinate) of the detector center position, and the deflection angle of the detector along the horizontal axis (i.e., X axis) corresponding to each step target position at each projection angle are output as motion trajectory parameters to form a motion trajectory parameter group. It should be noted that Figure 5In (b), P is the projection position of the target feature of the object to be measured, and (u, v) are the coordinates of the projection position. For example, assuming the geometric parameter group sets a multi-angle scanning range of 90°, 36 projections, and a starting angle of -45°, then 36 projection angles are obtained, each between -45° and 45°, and 36 projection angles correspond to 36 stepping target positions. When the motion trajectory of the wafer tomography is updated according to the linear trajectory moving along the Y-axis, 36 sets of motion trajectory parameter groups are obtained, including the longitudinal axis coordinates of the stage center, the longitudinal axis coordinates of the detector center position, and the detector deflection angle along the transverse axis.

[0082] When updating the motion trajectory of wafer tomography according to the circular trajectory, specifically: keep the position of the ray source unchanged, control the stage and the detector to move stepwise to the target position along the horizontal axis and the vertical axis of the object to be measured, respectively, and control the detector to deflect to a first target angle along the vertical axis of the object to be measured and to a second target angle along the horizontal axis of the object to be measured, so as to obtain the corresponding motion trajectory parameter group. For example, according to the parameters such as the scanning multi-angle range, the number of projections, the deflection angle, the starting angle, etc. in the geometric parameter group, multiple projection angles of the motion trajectory and their corresponding multiple step target positions can be pre-set. When updating the motion trajectory of wafer tomography, such as Figure 5As shown in (c) in the figure, the stage and the detector can be moved step by step to each step target position according to the preset step target position and sequence at each projection angle, and the horizontal axis coordinate (i.e., X-axis coordinate) and vertical axis coordinate (i.e., Y-axis coordinate) of the stage center corresponding to each step target position at each projection angle, the horizontal axis coordinate (i.e., X-axis coordinate) and vertical axis coordinate (i.e., Y-axis coordinate) of the detector center position, the deflection angle of the detector along the horizontal axis (i.e., X-axis), and the deflection angle of the detector along the vertical axis (i.e., Y-axis) are output as motion trajectory parameters to form a motion trajectory parameter group. For example, assuming the source-object distance set in the geometric parameter group is 1.0544mm, the source-image distance is 445.0630mm, the multi-angle scanning range is 360°, the number of projections is 36, the deflection angle is 40°, the starting angle is 0°, the starting stage center X coordinate is 366.6443mm, the starting stage center Y coordinate is 156.7327mm, the detector center position X coordinate is 320.8168mm, and the detector center position Y coordinate is 360.9374mm, then 36 projection angles are obtained, each between -40° and 40°, and the 36 projection angles correspond to 36 step target positions. When the wafer tomography motion trajectory is updated according to the circular trajectory, 36 sets of motion trajectory parameter groups are obtained, including the horizontal and vertical coordinates of the stage center, the horizontal and vertical coordinates of the detector center, the detector deflection angle along the horizontal axis, and the detector deflection angle along the vertical axis.

[0083] It can be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0084] In some embodiments of this application, please refer to Figure 6 , Figure 6 This is a basic structural block diagram of an online geometric correction device for wafer tomography provided in an embodiment of the present application. The various units included in the device in this embodiment are used to perform the various steps in the above method embodiment. For details, please refer to the relevant description in the above method embodiment. For ease of explanation, only the parts related to this embodiment are shown. Figure 6As shown, the online geometric correction device for wafer tomography includes: an acquisition module 61, a calculation module 62, and a correction module 63. The acquisition module 61 is configured to acquire first, second, and third projection images of the target feature under test at different magnifications, with the line connecting the radiation source focus and the center of the detector imaging plane perpendicular to the detection surface. The calculation module 62 is configured to calculate a corrected source-object distance and a corrected source-image distance based on the numerical relationship between the imaging parameters and the feature size reflected in the first, second, and third projection images, respectively. The imaging parameters include the source-object distance and the source-image distance, and the feature size includes the actual size and projected size of the target feature under test. The correction module 63 is configured to update a geometric correction parameter set based on the corrected source-object distance and the corrected source-image distance, and to update the motion trajectory of the wafer tomography based on the geometric correction parameter set, obtaining a corresponding motion trajectory parameter set, and saving the geometric correction parameter set and the motion trajectory parameter set for wafer tomography.

[0085] It should be understood that the above-mentioned online geometric correction device for wafer tomography corresponds one-to-one with the above-mentioned online geometric correction method for wafer tomography, and will not be described in detail here.

[0086] In some embodiments of this application, please refer to Figure 7 , Figure 7 This is a basic structural block diagram of an electronic device provided in an embodiment of the present application. Figure 7 As shown, the electronic device 7 of this embodiment includes: a processor 71, a memory 72, and a computer program 73 stored in the memory 72 and executable on the processor 71, such as a program for an online geometric correction method for wafer tomography. When the processor 71 executes the computer program 73, the steps described in the various embodiments of the online geometric correction method for wafer tomography described above are implemented. Alternatively, when the processor 71 executes the computer program 73, the functions of the modules described in the corresponding embodiments of the online geometric correction apparatus for wafer tomography described above are implemented. For details, please refer to the relevant descriptions in the embodiments and will not be repeated here.

[0087] Exemplarily, the computer program 73 may be divided into one or more modules (units) for executing the various steps in the above-described method embodiments. The one or more modules are stored in the memory 72 and executed by the processor 71 to implement the present application. The one or more modules may be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program 73 in the electronic device 7.

[0088] The electronic device may include, but is not limited to, a processor 71 and a memory 72. Those skilled in the art will understand that Figure 7 It is only an example of the electronic device 7 and does not constitute a limitation of the electronic device 7. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device may also include input and output devices, network access devices, buses, etc.

[0089] The processor 71 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0090] The memory 72 can be an internal storage unit of the electronic device 7, such as a hard drive or memory of the electronic device 7. The memory 72 can also be an external storage device of the electronic device 7, such as a plug-in hard drive, a Smart Media Card (SMC), a Secure Digital (SD) card, a flash memory card, etc. equipped on the electronic device 7. Furthermore, the memory 72 can include both an internal storage unit of the electronic device 7 and an external storage device. The memory 72 is used to store the computer program and other programs and data required by the electronic device. The memory 72 can also be used to temporarily store data that has been output or is about to be output.

[0091] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the method embodiment of this application. Their specific functions and technical effects can be found in the method embodiment section and will not be repeated here.

[0092] The present application also provides a computer-readable storage medium that stores a computer program. When the computer program is executed by a processor, the computer-readable storage medium can implement the steps of the above-mentioned method embodiments. In this embodiment, the computer-readable storage medium can be non-volatile or volatile.

[0093] An embodiment of the present application provides a computer program product. When the computer program product is run on a mobile terminal, the mobile terminal can implement the steps of the above-mentioned various method embodiments when executing the computer program product.

[0094] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned device can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0095] If the integrated module / unit is implemented as a software functional unit and sold or used as a standalone product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application can implement all or part of the process steps in the above-mentioned method embodiments by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When executed by a processor, the computer program can implement the steps of each of the above-mentioned method embodiments. The computer program includes computer program code, which can be in source code form, object code form, executable file, or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal, and software distribution medium. It should be noted that the content of the computer-readable medium can be appropriately increased or decreased based on the requirements of legislation and patent practice in a jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media does not include electric carrier signals and telecommunication signals.

[0096] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0097] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. An online geometric correction method for wafer tomography, characterized in that: include: When the line connecting the focus of the ray source and the center of the detector imaging plane is perpendicular to the detection surface, a first projection image, a second projection image and a third projection image of the target feature of the object to be measured at different magnifications are collected; Calculating a corrected source-object distance and a corrected source-image distance based on numerical relationships between imaging parameters and characteristic dimensions reflected by each of the first projection image, the second projection image, and the third projection image, wherein the imaging parameters include the source-object distance and the source-image distance, and the characteristic dimensions include the actual dimensions and the projected dimensions of the target feature of the object to be measured; According to the corrected source-object distance and the corrected source-image distance, a geometric correction parameter group is updated, and the motion trajectory of wafer tomography is updated according to the geometric correction parameter group to obtain a corresponding motion trajectory parameter group, and the geometric correction parameter group and the motion trajectory parameter group are saved for wafer tomography.

2. The online geometric correction method for wafer tomography according to claim 1, characterized in that: The step of acquiring a first projection image, a second projection image, and a third projection image of the target feature of the object to be measured at different magnifications when the line connecting the focus of the ray source and the center of the imaging plane of the detector is perpendicular to the detection surface includes: Adjusting the position of the stage toward the side of the ray source along the direction of the line connecting the ray source focus and the center of the detector imaging plane to obtain different magnifications of the target feature of the object to be measured; and / or Adjusting the position of the detector toward the side of the ray source along the direction of the line connecting the focus of the ray source and the center of the detector imaging plane to obtain different magnifications of the target feature of the object to be measured; and / or The position of the ray source is adjusted toward one side of the detector along the direction of the line connecting the focus of the ray source and the center of the imaging plane of the detector to obtain different magnifications of the target feature of the object to be measured.

3. The online geometric correction method for wafer tomography according to claim 1, characterized in that: The step of calculating the corrected source-object distance and the corrected source-image distance based on the numerical relationship between the imaging parameters and the characteristic dimensions reflected by the first projection image, the second projection image, and the third projection image comprises: Calculating based on the numerical relationship between the imaging parameters and the characteristic size reflected in the first projection image and the numerical relationship between the imaging parameters and the characteristic size reflected in the second projection image to obtain a corrected source-object distance; The corrected source-image distance is obtained by performing calculation based on the corrected source-object distance in combination with the numerical relationship between the imaging parameters and the characteristic size reflected in the second projection image and the numerical relationship between the imaging parameters and the characteristic size reflected in the third projection image.

4. The online geometric correction method for wafer tomography according to claim 1, wherein: After the step of calculating the corrected source-object distance and the corrected source-image distance based on the numerical relationship between the imaging parameters and the characteristic size reflected by the first projection image, the second projection image, and the third projection image, the method further includes: After adjusting the position of the detector or the position of the ray source along the direction of the line connecting the focus of the ray source and the center of the detector imaging plane, a fourth projection image is acquired; Based on the fourth projection image, performing calibration processing on the corrected source-object distance according to a preset calibration formula to determine whether the corrected source-object distance and the corrected source-image distance meet a preset accuracy condition; If the corrected source-object distance and the corrected source-image distance do not meet the preset accuracy conditions, recalculating the corrected source-object distance according to a preset source-object distance calculation formula and recalculating the corrected source-image distance based on the recalculated source-object distance; The preset verification formula is: ; SOD is the corrected source-object distance, SDD is the corrected source-image distance; ΔX4 is the projection size of the target feature of the object to be measured on the detector, δx is the actual size of the target feature of the object to be measured, and z4 is the adjustment distance of the detector position or the ray source position; the preset source-object distance calculation formula is SOD = z4+(SDD-z4)*δx / ΔX4.

5. The online geometric correction method for wafer tomography according to claim 1, wherein: Before the step of acquiring the first projection image, the second projection image, and the third projection image of the target feature of the object to be measured at different magnifications when the line connecting the focus of the ray source and the center of the imaging plane of the detector is perpendicular to the detection surface, the method further includes: Placing the object to be tested on the stage, performing target detection on the object to be tested, and determining the target features of the object to be tested; Acquire a fifth projection image and a sixth projection image of the target feature of the object to be measured at different magnifications; Adjust the positions of the stage and the detector in the plane direction according to the fifth projection image and the sixth projection image until the projection position of the target feature of the object to be measured on the detector remains unchanged and coincides with the center of the imaging plane of the detector, so that the line connecting the focus of the ray source and the center of the imaging plane of the detector is perpendicular to the detection surface, wherein the plane direction includes the longitudinal axis direction and the transverse axis direction of the object to be measured.

6. The online geometric correction method for wafer tomography according to claim 5, characterized in that: The step of placing the object to be tested on the stage, performing target detection on the object to be tested, and determining the target characteristics of the object to be tested includes: Performing target detection on the object to be detected by moving the stage in a direction perpendicular to the plane of the stage to determine the target features of the object to be detected; or Target detection is performed on the object to be detected by performing dynamic perspective on the object to be detected, so as to determine the target characteristics of the object to be detected.

7. The online geometric correction method for wafer tomography according to any one of claims 1 to 6, characterized in that: The step of updating the motion trajectory of wafer tomography according to the geometric correction parameter group to obtain a corresponding motion trajectory parameter group includes: Keeping the position of the ray source unchanged, controlling the stage and the detector to move stepwise to the target position along the horizontal axis of the object to be measured, and controlling the detector to deflect to a first target angle along the vertical axis of the object to be measured, so as to obtain a corresponding motion trajectory parameter set; or Keeping the position of the ray source unchanged, controlling the stage and the detector to move stepwise to the target position along the longitudinal axis of the object to be measured, and controlling the detector to deflect to a second target angle along the transverse axis of the object to be measured, so as to obtain a corresponding motion trajectory parameter set; or Keeping the position of the ray source unchanged, the stage and the detector are controlled to move step by step to the target position along the horizontal axis and the vertical axis of the object to be measured respectively, and the detector is controlled to deflect to a first target angle along the vertical axis of the object to be measured and to a second target angle along the horizontal axis of the object to be measured, so as to obtain a corresponding motion trajectory parameter group.

8. An online geometric correction device for wafer tomography, characterized in that: include: An acquisition module is used to acquire a first projection image, a second projection image, and a third projection image of the target feature of the object to be measured at different magnifications when the line connecting the focus of the ray source and the center of the detector imaging plane is perpendicular to the detection surface; a calculation module, configured to calculate a corrected source-object distance and a corrected source-image distance based on a numerical relationship between imaging parameters and characteristic dimensions reflected by each of the first projection image, the second projection image, and the third projection image, wherein the imaging parameters include the source-object distance and the source-image distance, and the characteristic dimensions include the actual dimensions and the projected dimensions of the target feature of the object to be measured; The correction module is used to update the geometric correction parameter group according to the corrected source-object distance and the corrected source-image distance, and update the motion trajectory of wafer tomography according to the geometric correction parameter group, obtain a corresponding motion trajectory parameter group, and save the geometric correction parameter group and the motion trajectory parameter group for wafer tomography.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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