On-line geometric correction method and device for wafer tomography

Abstract

The invention provides an on-line geometric correction method and device for wafer tomography, and the method comprises the steps: collecting a first projection image, a second projection image and a third projection image of the target features of an object to be detected under different magnification times under the condition that a connection line between the focus of a radiation 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 according to the numerical relationship between the imaging parameters and the feature sizes respectively reflected by the first projection image, the second projection image and the third projection image; and updating a geometric correction parameter group according to the corrected source object distance and the corrected source image distance, updating a movement track of the wafer tomography according to the geometric correction parameter group, obtaining a corresponding movement track parameter group, and storing the geometric correction parameter group and the movement track parameter group for the wafer tomography. According to the method, the problem of geometric correction parameter distortion caused by focus drift in online tomography is solved, and the cost is low.

Description

Technical Field

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

[0002] Wafer Laminography is a technology for three-dimensionally imaging the internal structure of a wafer. High-precision three-dimensional reconstruction by tomography has strict requirements for geometric correction. During the imaging process, due to various factors such as sample placement, geometric distortion will occur. By geometric correction, the distortion can be corrected to obtain a more accurate image. Existing geometric correction methods include using a phantom correction and offline iterative correction, etc. Among them, the method of geometric correction through a specific phantom has high requirements for the accuracy of the specific phantom, and deviations in the phantom parameters will lead to incorrect calculation of the rotation center. And iterative correction requires estimating the rotation center, reconstructing the image based on the estimated rotation center, observing the distortion in the reconstructed image, and repeatedly adjusting the estimated rotation center until the geometric distortion of the reconstructed image reaches the minimum. This method is complex and time-consuming. Moreover, during the online tomography process of the wafer, inaccurate rotation center will cause the projection of the object to be measured on the detector imaging plane to shift, resulting in artifacts and distortions in the three-dimensional reconstruction. The existing phantom correction and iterative correction methods cannot solve the problem of parameter distortion caused by the drift of the ray source focus position in online tomography. Summary of the Invention

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

[0004] The first aspect of the embodiment of the present application provides an online geometric correction method for wafer tomography imaging, including: when the line connecting the ray source focus and the center of the detector imaging plane is perpendicular to the detection plane, 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 magnification factors; calculating the corrected source-object distance and the corrected source-image distance according to the numerical relationship between the imaging parameters and the feature size reflected by each of the first projection image, the second projection image, and the third projection image, where the imaging parameters include the source-object distance and the source-image distance, and the feature size includes the actual size and the projection size of the target feature of the object to be measured; updating the geometric correction parameter group according to the corrected source-object distance and the corrected source-image distance, and updating the motion trajectory of the wafer tomography imaging according to the geometric correction parameter group to obtain the corresponding motion trajectory parameter group, and saving the geometric correction parameter group and the motion trajectory parameter group for wafer tomography imaging.

[0005] In a possible implementation manner, 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 magnification factors when the line connecting the ray source focus and the center of the detector imaging plane is perpendicular to the detection plane includes: adjusting the position of the stage in the direction of the line connecting the ray source focus and the center of the detector imaging plane towards the ray source side to obtain different magnification factors of the target feature of the object to be measured; and / or adjusting the position of the detector in the direction of the line connecting the ray source focus and the center of the detector imaging plane towards the ray source side to obtain different magnification factors of the target feature of the object to be measured; and / or adjusting the position of the ray source in the direction of the line connecting the ray source focus and the center of the detector imaging plane towards the detector side to obtain different magnification factors of the target feature of the object to be measured.

[0006] In a possible implementation manner, the step of calculating the corrected source-object distance and the corrected source-image distance according to the numerical relationship between the imaging parameters and the feature size reflected by each of the first projection image, the second projection image, and the third projection image includes: calculating according to the numerical relationship between the imaging parameters and the feature size reflected in the first projection image combined with the numerical relationship between the imaging parameters and the feature size reflected in the second projection image to obtain the corrected source-object distance; calculating according to the corrected source-object distance combined with the numerical relationship between the imaging parameters and the feature size reflected in the third projection image to obtain the corrected source-image distance.

[0007] In a possible implementation manner, after the step of calculating the corrected source object distance and the corrected source image distance according to the numerical relationship between the imaging parameters and the feature sizes respectively 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 connection line between the ray source focus and the center of the detector imaging plane, acquiring a fourth projection image; based on the fourth projection image, performing a verification process on the corrected source object distance according to a preset verification formula, and determining whether the corrected source object distance and the corrected source image distance meet the preset accuracy conditions; 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; wherein, the preset verification formula is: ; SOD is the corrected source object distance, SDD is the corrected source image distance; ΔX4 is the projected 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 position of the detector or the ray source; the preset source object distance calculation formula is SOD = z4+(SDD - z4)*δx / ΔX4.

[0008] In a possible implementation manner, 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 magnification factors when the connection line between the ray source focus and the center of the detector imaging plane is perpendicular to the detection surface, the method further includes: placing the object to be measured on the stage, performing target detection on the object to be measured to determine the target feature of the object to be measured; acquiring the fifth projection image and the sixth projection image of the target feature of the object to be measured at different magnification factors; 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 projected position of the target feature of the object to be measured on the detector remains unchanged and coincides with the center of the detector imaging plane, so that the connection line between the ray source focus and the center of the detector imaging plane is perpendicular to the detection surface, wherein the plane direction includes the longitudinal axis center line direction and the transverse axis center line direction of the object to be measured.

[0009] In a possible implementation manner, the step of 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 includes: performing target detection on the object to be measured by moving the stage along the direction perpendicular to the stage plane to determine the target feature of the object to be measured; or performing target detection on the object to be measured by performing dynamic perspective on the object to be measured to determine the target feature of the object to be measured.

[0010] In a possible implementation manner, the step of updating the motion trajectory of the 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 stepwise move to a target position along the horizontal axis central axis direction of the object to be measured, and controlling the detector to deflect to a first target angle along the vertical axis central axis of the object to be measured, so as to obtain a corresponding motion trajectory parameter group; or keeping the position of the ray source unchanged, controlling the stage and the detector to stepwise move to a target position along the vertical axis central axis direction of the object to be measured, and controlling the detector to deflect to a second target angle along the horizontal axis central axis of the object to be measured, so as to obtain a corresponding motion trajectory parameter group; or keeping the position of the ray source unchanged, controlling the stage and the detector to stepwise move to a target position along the horizontal axis central axis direction and the vertical axis central axis direction of the object to be measured respectively, and controlling the detector to deflect to a first target angle along the vertical axis central axis of the object to be measured and deflect to a second target angle along the horizontal axis central axis of the object to be measured, so as to obtain a corresponding motion trajectory parameter group.

[0011] In a second aspect of the embodiments of the present application, an on-line geometric correction device for wafer tomography is provided, including: an acquisition module, configured to acquire 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 magnification factors when the line connecting the ray source focus and the center of the detector imaging plane is perpendicular to the detection plane; a calculation module, configured to calculate a corrected source-object distance and a corrected source-image distance according to the numerical relationship between the imaging parameters and the feature sizes reflected by the first projection image, the second projection image, and the third projection image respectively, where 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, configured 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 the wafer tomography according to the geometric correction parameter group to obtain a corresponding motion trajectory parameter group, and save the geometric correction parameter group and the motion trajectory parameter group for wafer tomography.

[0012] In a third aspect of the embodiments of the present application, an electronic device is provided, including 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 on-line geometric correction method for wafer tomography provided in the first aspect are implemented.

[0013] In a fourth aspect of the embodiments of the present application, a computer-readable storage medium is provided. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the on-line 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, which, when running on an electronic device, enables the electronic device to execute the steps of the online geometric correction method for wafer tomography provided in the first aspect.

[0015] An online geometric correction method and device for wafer tomography provided by the embodiments of the present application, as well as an electronic device and a storage medium for executing the online geometric correction method for wafer tomography, have the following beneficial effects: In the present application, when the line connecting the focus of the radiation source and the center of the detector imaging plane is perpendicular to the detection plane, the first projection image, the second projection image, and the third projection image of the target characteristics of the object to be measured at different magnification factors are collected; according to 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 respectively, the corrected source-object distance and the corrected source-image distance are calculated; according to the corrected source-object distance and the corrected source-image distance, the geometric correction parameter group is updated, 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 geometric correction parameter group and the motion trajectory parameter group are saved for wafer tomography. This method solves the problem of distortion of geometric correction parameters caused by focus drift in online tomography. At the same time, it reduces the requirements for high-precision position movement and position sensing. On the premise of ensuring the accuracy and quality of three-dimensional image reconstruction, the system cost is greatly reduced. Moreover, the operation is simple and efficient, with strong repeatability and applicability, and is insensitive to noise and jitter. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0017] Figure 1 It is a flowchart for implementing an online geometric correction method for wafer tomography provided by the embodiments of the present application; Figure 2 It is a flowchart for implementing the calculation of the corrected source-object distance and the corrected source-image distance in the online geometric correction method for wafer tomography provided by the embodiments of the present application; Figure 3 It is a flowchart for verifying the corrected source-object distance in the online geometric correction method for wafer tomography provided by the embodiments of the present application; Figure 4It is a flowchart showing an implementation of adjusting the line connecting the ray source focus and the center of the detector imaging plane to be perpendicular to the detection plane in the online geometric correction method for wafer tomography provided by an embodiment of the present application; Figure 5 It is a schematic diagram showing the movement trajectories of three types of wafer tomography in the online geometric correction method for wafer tomography provided by an embodiment of the present application; Figure 6 It is a basic structural block diagram of an online geometric correction device for wafer tomography provided by an embodiment of the present application; Figure 7 It is a basic structural block diagram of an electronic device provided by an embodiment of the present application. Detailed implementation manners

[0018] In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also 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 unnecessary details from interfering with the description of the present application.

[0019] It should be understood that when used in the specification and the appended claims of the present application, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0020] It should also be understood that the term "and / or" as used in the specification and the appended claims of the present application refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0021] As used in the specification and the appended claims of the present application, the term "if" can be interpreted as "when", "once", "in response to determining", or "in response to detecting" according to the context. Similarly, the phrase "if determined" or "if detecting [the described condition or event]" can be interpreted as meaning "once determined", "in response to determining", "once detecting [the described condition or event]", or "in response to detecting [the described condition or event]" according to the context.

[0022] In addition, in the description of the specification and the appended claims of the present application, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0023] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that a specific feature, structure, or characteristic described in connection with that embodiment is included in one or more embodiments of this application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but rather mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized. "Plurality" means "two or more".

[0024] In order to make the objectives, technical solutions and advantages of this application clearer and more understandable, the following further details this application in conjunction with 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 used to limit this application.

[0025] The existing X-ray tomography geometric correction process is cumbersome and has the following disadvantages: The traditional geometric correction method has high requirements for the accuracy of the system model, high requirements for the accuracy of the scanning angle and position, and is prone to reconstruction artifacts; The image iterative correction method is relatively complex and time-consuming for multiple iterations; It relies on a phantom; The offline correction is sensitive to noise and jitter and has poor applicability; Appropriate exposure parameters are required for correction, and there are many prerequisite conditions for correction; Interference factors such as focus drift and stage jitter result in the need for multiple offline corrections of the phantom, increasing the time cost and correction difficulty; The position of the correction phantom is inconsistent with the position of the actual sample, which is likely to cause distortion of the correction parameters. In view of the above disadvantages, this application aims to provide an online geometric correction method and device for wafer tomography. Through online geometric correction, it is possible to adjust the calculated coordinates in real time according to interference such as noise and jitter, with strong applicability and without the need to rely on a phantom. In addition, online calculation can save time costs, is not affected by exposure parameters, and is not subject to interference such as phantom accuracy. Even if interference such as focus drift and stage jitter occurs, the motion trajectory can be adjusted through real-time online geometric correction, and the artifacts and geometric distortions brought to the reconstruction can be eliminated in a timely manner.

[0026] In some embodiments of this application, please refer to Figure 1 , Figure 1 which is a flowchart of the implementation of an online geometric correction method for wafer tomography provided by an embodiment of this application. As Figure 1 shown, it specifically may include steps S11 to S13.

[0027] S11: When the line connecting the focus of the radiation source and the center of the detector imaging plane is perpendicular to the detection plane, collect the first projection image, the second projection image, and the third projection image of the target features of the object to be measured at different magnification factors.

[0028] In this embodiment, based on the requirements of the three-dimensional reconstruction algorithm, such as the FDK (full English name: Feldkamp-Davis-Kress) algorithm, it is necessary to accurately know the coordinates of the projection point of the focus center of the radiation source on the imaging plane of the detector. In the imaging system for actual application, the error of the projection point will affect the accuracy of the reconstructed image, cause the generation of artifacts, and affect the resolution of the image and the effective detection of details. In a specific implementation manner, the position of the focus center of the radiation source can be tracked online, and the position of the focus center relative to the center of the detector imaging plane can be adjusted according to the change of the projection position of the object to be measured on the detector imaging plane, so that the line connecting the focus of the radiation source and the center of the detector imaging plane is always perpendicular to the detection plane, which can ensure that the rotation center for three-dimensional reconstruction remains unchanged, ensure the quality of the collected images, and increase the robustness of the quality of the reconstructed images. In this embodiment, the magnification factor is equal to the ratio of the source-object distance to the source-image distance. When collecting the projection images of the target features of the object to be measured, the first projection image, the second projection image, and the third projection image of the target features of the object to be measured at different magnification factors can be collected by changing the imaging parameters several times. Among them, the imaging parameters include the source-object distance and the source-image distance. The source-object distance is represented as the distance between the focus center of the radiation source and the object to be measured, and the source-image distance is represented as the distance between the focus center of the radiation source and the center of the detector imaging plane.

[0029] S12: According to the numerical relationships between the imaging parameters and the feature sizes reflected by the first projection image, the second projection image, and the third projection image respectively, calculate the corrected source-object distance and the corrected source-image distance, where 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 features of the object to be measured.

[0030] In this embodiment, the first projection image, the second projection image, and the third projection image are projection images at different magnification factors, and the numerical values of the imaging parameters and the feature sizes reflected by them are different. 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 features of the object to be measured. The numerical relationship between the imaging parameters and the feature sizes is specifically manifested as the ratio of the source-object distance to the source-image distance being equal to the ratio of the actual size to the projection size. According to the first projection image, the second projection image, and the third projection image, three sets of numerical relational expressions 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 projection size can be correspondingly obtained. Based on these three sets of numerical relational expressions for joint calculation, more accurate source-object distance and source-image distance can be calculated as the corrected source-object distance and the corrected source-image distance.

[0031] S13: Update the geometric correction parameter set according to the corrected source-object distance and the corrected source-image distance, and update the motion trajectory of the wafer tomography according to the geometric correction parameter set to obtain the corresponding motion trajectory parameter set, and save the geometric correction parameter set and the motion trajectory parameter set for wafer tomography.

[0032] In this embodiment, the geometric correction parameter set includes the source-object distance, the source-image distance, the scanning multi-angle range, the number of projections, the deflection angle, the starting angle, the horizontal and vertical coordinates of the starting stage center, the horizontal and vertical coordinates of the detector center position, etc. Except for the two parameters of the source-object distance and the 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 set mainly updates the two parameters of the source-object distance and the source-image distance in the geometric correction parameter set 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, multiple projection angles of the motion trajectory can be determined by parameters such as the scanning multi-angle range, the number of projections, the deflection angle, and the starting angle in the geometric correction parameter set. When updating the motion trajectory of the wafer tomography, the motion trajectory parameters under each projection angle condition of the motion trajectory can be output to form the motion trajectory parameter set. 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 position, the detector deflection angle along the vertical axis, and the detector deflection angle along the horizontal axis under each projection angle condition. After updating to obtain the geometric parameter set and the motion trajectory parameter set, the geometric parameter set and the motion trajectory parameter set are saved for the process of three-dimensional reconstruction in wafer tomography.

[0033] As can be seen above, in the online geometric correction method for wafer tomography provided by the embodiments of the present application, when the line connecting the ray source focus and the center of the detector imaging plane is perpendicular to the detection plane, projection images with different magnification factors are collected. Based on the numerical relationship between the imaging parameters reflected by the projection images with different magnification factors and the feature size, the corrected source-object distance and the corrected source-image distance are calculated. 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 wafer tomography is updated according to the geometric correction parameter group to obtain the corresponding motion trajectory parameter group. 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 ray source focus, adjusts the position of the focus center relative to the center of the detector imaging plane according to the change in the projection position of the object to be measured on the detector imaging plane, ensures that the rotation center for three-dimensional reconstruction remains unchanged, ensures the quality of the collected images, and increases the robustness of the quality of the reconstructed images. By changing the imaging parameters several times, the source-object distance and the source-image distance can be accurately obtained. 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. On the premise of ensuring the accuracy and quality of three-dimensional image reconstruction, the system cost is greatly reduced.

[0034] In some embodiments of the present application, when collecting the projection image of the target feature of the object to be measured, different magnification factors of the target feature of the object to be measured can be obtained by adjusting the relative position of any one of the ray source, the stage, or the detector in the direction of the line connecting the ray source focus and the center of the detector imaging plane. Exemplarily, the position of the stage can be adjusted towards the ray source side along the line connecting the ray source focus and the center of the detector imaging plane to shorten the distance between the ray source and the stage, that is, shorten the source-object distance, so as to obtain different magnification factors of the target feature of the object to be measured. Exemplarily, the position of the detector can also be adjusted towards the ray source side along the line connecting the ray source focus and the center of the detector imaging plane to shorten the distance between the ray source and the detector, that is, shorten the source-image distance, so as to obtain different magnification factors of the target feature of the object to be measured. Exemplarily, the position of the ray source can also be adjusted towards the detector side along the line connecting the ray source focus and the center of the detector imaging plane to shorten the distance between the ray source and the stage and the distance between the ray source and the detector, that is, shorten the source-object distance and the source-image distance simultaneously, so as to obtain different magnification factors of the target feature of the object to be measured.

[0035] In some embodiments of the present application, please refer to Figure 2 , Figure 2A 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.

[0036] S21: performing calculation according to the numerical relationship between the imaging parameter and the characteristic size reflected in the first projection image and the numerical relationship between the imaging parameter and the characteristic size reflected in the second projection image to obtain a corrected source-object distance; 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.

[0037] In this embodiment, the first projection image may be a projection image directly acquired without adjusting the relative positions of the radiation source, the stage and the detector after determining that the line connecting the focus of the radiation source and the center of the imaging plane of the detector is perpendicular to the detection surface. The second projection image may be a projection image acquired after the first projection image is acquired by adjusting the position of the stage toward the radiation source along the direction of the line connecting the focus of the radiation source and the center of the imaging plane of the detector so that the relative distance between the radiation source and the stage is shortened by z1. The third projection image may be a projection image acquired after the second projection image is acquired by adjusting the position of the detector toward the radiation source along the direction of the line connecting the focus of the radiation source and the center of the imaging plane of the detector so that the relative distance between the radiation source and the detector is shortened by z2.

[0038] Since the first projection image, the second projection image and the third projection image project the same target feature of the object to be measured, the actual size of the target feature of the object to be measured reflected by the three projection images is δx. Since the magnifications corresponding to the first projection image, the second projection image and the third projection image are different, the projection sizes of the target features of the object to be measured reflected in the three projection images are also different, namely ΔX, ΔX1 and ΔX2. Assuming that the source object distance reflected by the first projection image is SOD and the source image distance is SDD, then the source object distance reflected by the second projection image is SOD-z1 and the source image distance is SDD, and the source object distance reflected by the third projection image is SOD-z1 and the source image distance is SDD-z2.

[0039] According to the first projection image, the following numerical relationship 1 can be obtained:

[0040] According to the second projection image, the following numerical relationship equation 2 can be obtained:

[0041] According to the third projection image, the following numerical relationship three can be obtained:

[0042] At this time, by combining numerical relationship one and numerical relationship two, performing a correction calculation on the source object distance in the numerical relationship, a more accurate source object distance can be obtained as the corrected source object distance. After obtaining the corrected source object distance, substitute the corrected source object distance into numerical relationship two and numerical relationship three, and combine numerical relationship two and numerical relationship three to perform a correction calculation on the source image distance in the numerical relationship, and a more accurate source image distance can be obtained as the corrected source image distance.

[0043] In a specific embodiment, the third projection image can also be a projection image obtained by adjusting the position of the radiation source toward the detector side along the direction of the line connecting the radiation source focus and the center of the detector imaging plane after collecting the second projection image, so that the relative distances between the radiation source and the stage and the detector are both shortened by z3. Correspondingly, 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. According to the third projection image, the following numerical relationship four can be obtained:

[0044] At this time, by substituting the corrected source object distance into numerical relationship two and numerical relationship four, and combining numerical relationship two and numerical relationship four to perform a correction calculation on the source image distance in the numerical relationship, a more accurate source image distance can also be obtained as the corrected source image distance.

[0045] In a specific embodiment, the second projection image can also be a projection image obtained by adjusting the position of the radiation source toward the detector side along the direction of the line connecting the radiation source focus and the center of the detector imaging plane after collecting the first projection image, so that the relative distance between the radiation source and the stage is shortened by z5. Correspondingly, 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. According to the second projection image, the following numerical relationship five can be obtained:

[0046] At this time, by combining numerical relationship one and numerical relationship five to perform a correction calculation on the source object distance in the numerical relationship, a more accurate source object distance can also be obtained as the corrected source object distance.

[0047] In some embodiments of the present application, please refer to Figure 3 , Figure 3This is a flowchart showing one implementation of verifying the corrected source-object distance in the online geometric correction method for wafer tomography provided by the embodiments of this application. As Figure 3 shown, it may specifically include steps S31 to S33.

[0048] S31: After adjusting the position of the detector or the position of the radiation source along the direction connecting the focus of the radiation source and the center of the detector imaging plane, a fourth projection image is collected; S32: Based on the fourth projection image, the corrected source-object distance is verified according to a preset verification formula to determine whether the corrected source-object distance and the corrected source-image distance meet the preset accuracy conditions; S33: If the corrected source-object distance and the corrected source-image distance do not meet the preset accuracy conditions, the corrected source-object distance is recalculated according to a preset source-object distance calculation formula, and the corrected source-image distance is recalculated 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 position of the detector or the radiation source; the preset source-object distance calculation formula is SOD = z4+(SDD - z4)*δx / ΔX4.

[0049] In this embodiment, since the accuracy requirement for the value of the source-object distance is very high during the wafer tomography process, which can reach the level of hundreds of micrometers, and considering that there may be calculation errors when extracting image target features during online geometric correction and the error caused by inaccurate reading of the relative distance z between the radiation 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 implementation manner, after calculating the corrected source-object distance and the corrected source-image distance, the position of the detector can be adjusted towards the radiation source along the direction connecting the focus of the radiation source and the center of the detector imaging plane, so that the relative distance between the radiation source and the detector is shortened by z4, and then a fourth projection image is collected. At this time, the projection size of the target feature of the object to be measured reflected in the fourth projection image on the detector is ΔX4. The corrected source-object distance is verified according to the following verification formula:

[0050] Substitute the corrected source object distance and the corrected source image distance into the above verification formula for verification to determine whether the formula holds. If the formula holds, it is considered that the corrected source object distance and the corrected source image distance meet the preset accuracy conditions. If the formula does not hold, it is considered that the corrected source object distance and the corrected source image distance do not meet the preset accuracy conditions. At this time, the corrected source object distance needs to be recalculated. Specifically, the corrected source object distance can be recalculated through the following source object distance calculation formula: SOD = z4+(SDD - z4)*δx / ΔX4.

[0051] Further, after verification, if the corrected source object distance has been recalculated, then use the recalculated source object distance as the latest corrected source object distance to calculate in combination with the numerical relationship between the imaging parameters and the feature size reflected in the second projection image and the numerical relationship between the imaging parameters and the feature size reflected in the third projection image, so as to recalculate the corrected source image distance.

[0052] In some embodiments of the present application, please refer to Figure 4 , Figure 4 is a flowchart of an implementation for adjusting the connection line between the ray source focus and the center of the detector imaging plane to be perpendicular to the detection surface in the on-line geometric correction method for wafer tomography imaging provided by the embodiments of the present application. As Figure 4 shown, it may specifically include steps S41 to S43.

[0053] S41: Place the object to be measured on the stage, perform target detection on the object to be measured, and determine the target features of the object to be measured; S42: Collect the fifth projection image and the sixth projection image of the target features of the object to be measured at different magnification factors; 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 features 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 connection line between the ray source focus and the center of the detector imaging plane is perpendicular to the detection surface, where the plane direction includes the longitudinal axis center line direction and the transverse axis center line direction of the object to be measured.

[0054] A wafer tomography system generally includes an X-ray source, a detector, and a stage. The ideal geometric structure for the wafer tomography process is as follows: The X-ray beam emitted from the center of the X-ray source focus passes through the rotation center. The lines connecting the center of the X-ray source focus, the center of the target feature to be measured in the stage, and the center of the detector imaging plane are always perpendicular to the detector imaging plane. In an actual wafer tomography system, there are offsets in various directions for the X-ray source and the detector. Among them, the offsets of the X-ray source and the stage can be converted into the offsets of the projection positions on the detector imaging plane. During the wafer tomography process, in order to obtain sufficient details of the wafer, the magnification factor during imaging is generally as large as several hundred, and can even reach several thousand at the highest. However, the larger the magnification factor, the higher the requirement for suppressing the drift of the X-ray source focus, and the more sensitive it is to the slightest change in the drift of the X-ray source focus. When the magnification factor is large enough, the geometric correction parameters will fail, thus affecting the 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 material undergoes minute deformation due to thermal expansion and contraction, which in turn causes the position of the effective focus to drift. This drift phenomenon is inherent. Existing methods for suppressing the offset of the X-ray source focus, such as increasing air cooling, liquid cooling, etc. to cool the X-ray source and controlling the movement with a precision sub-micron-level console, are expensive in terms of hardware cost, complex to control, and cannot completely eliminate it.

[0055] In this embodiment, when using a wafer tomography imaging system to perform wafer tomography imaging on a measurement object, the wafer tomography imaging system can be pre-calibrated first to adjust the line connecting the ray source focus and the center of the detector imaging plane in the wafer tomography imaging system to be perpendicular to the detection plane. Specifically, assuming that the Y-axis is the longitudinal axis center line of the measurement object, the X-axis is the transverse axis center line of the measurement object, 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 measurement object (i.e., the wafer) is transported to the target position on the stage and fixed on the stage, and then the ray source, the stage, and the detector in the wafer tomography imaging system are moved to the preset positions. At this time, in principle, the projection coordinates of the ray source focus center on the detector imaging plane completely coincide with the center of the detector imaging plane, but due to various factors such as the placement of the measurement object, there are errors, resulting in the projection coordinates of the ray source focus center on the detector imaging plane not coinciding with the center of the detector imaging plane. In this embodiment, by moving the stage in the X-axis direction and the Y-axis direction, high-frame-rate target detection is performed on the measurement object to find the area with obvious features in the measurement object, and this area is determined as the target feature of the measurement object. After determining the target feature of the measurement object, a fifth projection image is directly acquired under the current imaging parameter configuration of the wafer tomography imaging system. Then, after moving the position of the stage in the Z-axis direction, a sixth projection image of the target feature of the measurement object is acquired. Further, according to the fifth projection image and the sixth projection image, the positions of the stage and the detector in the plane direction are adjusted. In a specific implementation manner, when adjusting the position of the stage in the plane direction, specifically, the projection positions of the target feature of the measurement object in the fifth projection image and the sixth projection image can be compared in terms of position. If the projection positions of the target feature of the measurement object in the two projection images change in the X-axis direction, the position of the stage in the X-axis direction is adjusted and a new projection image is acquired as the new sixth projection image for comparison with the fifth projection image until the projection position of the target feature of the measurement object does not change in the X-axis direction. At this time, the adjustment of the position of the stage in the X-axis direction is stopped and the current X-axis coordinate of the stage is saved. If the projection positions of the target feature of the measurement object in the two projection images change in the Y-axis direction, the position of the stage in the Y-axis direction is adjusted and a new projection image is acquired as the updated sixth projection image for comparison with the fifth projection image until the projection position of the target feature of the measurement object does not change in the Y-axis direction. At this time, the adjustment of the position of the stage in the Y-axis direction is stopped and the current Y-axis coordinate of the stage is saved. In this embodiment, the judgment criterion for whether the projection position changes 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 planar direction, fix the radiation source and the stage and update the sixth projection image. According to the updated sixth projection image, move 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 centered in the X-axis direction of the detector imaging plane, and move 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 centered in the Y-axis direction of the detector imaging plane. Save the X-axis coordinate and Y-axis coordinate of the detector at this time. Thus, the adjustment of the detector in the planar direction is completed. By adjusting the positions of the stage and the detector in the planar 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 radiation source focus and the center of the detector imaging plane is perpendicular to the detection plane. It can be understood that the planar direction refers to the X-axis direction and the Y-axis direction.

[0056] In a specific embodiment, the sixth projection image can also be obtained by collecting after moving the radiation source in the Z-axis direction.

[0057] In a specific embodiment, after moving the radiation source, the stage, and the detector in the wafer tomography system to the preset positions, a spirit level is also used to adjust the horizontal flatness of the stage in the X and Y directions at zero position and collect the spirit level to adjust the horizontal flatness of the detector in the X and Y directions at zero position, so as to improve the accuracy of geometric correction.

[0058] In some embodiments of the present application, when determining the target characteristics of the object to be measured through target detection of the object to be measured, specifically, the wafer Notch can be found, and by imaging the Notch and extracting the orientation and position of the Notch, the center of the wafer can be quickly and preliminarily located. Among them, Notch is a physical notch used to identify the wafer direction, usually a V-shaped or U-shaped groove, located at the bottom edge of the silicon wafer, with precise position and easy to be read by the machine. In order to quickly find the wafer edge, the magnification can be set to a smaller value first, such as 5 - 50 times, until the wafer edge is detected, then the wafer edge is binarized to obtain the fitting circle curve function, and the center coordinates obtained 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 characteristics of the object to be measured can also be a stripe, multiple stripes, a triangle, a circle, the gap of the wafer cutting channel, or a graphic of other shapes on the wafer. The methods of target detection include image processing means such as edge detection, threshold segmentation, and contour acquisition of the projection image, used to obtain the contour end coordinates of the projection image. In this embodiment, for the same target characteristic under the conditions of the same magnification and the same acquisition angle, the shape and gray value remain unchanged before and after, only the size changes proportionally according to the magnification. According to this feature, the target characteristic of the object to be measured can be quickly found by statically photographing the projection image by moving the stage along the direction perpendicular to the stage plane. It can be understood that the direction perpendicular to the stage plane is the Z-axis direction. In this embodiment, in addition to static photographing, the target characteristic of the object to be measured can also be quickly found by dynamically penetrating the object to be measured, and the movement trajectory of the target characteristic of the object to be measured is also clearly visible during the multi-frame acquisition of dynamic penetration.

[0059] In some embodiments of the present application, the movement trajectory of wafer tomography can be any one of a straight-line trajectory moving along the X-axis direction, a straight-line trajectory moving along the Y-axis direction, and a circular trajectory. Specifically, as Figure 5 shown, Figure 5 is a schematic diagram of three movement trajectories of wafer tomography in the online geometric correction method of wafer tomography provided by the embodiment of the present application.

[0060] When updating the movement trajectory of wafer tomography according to the straight-line trajectory moving along the X-axis direction, specifically: keeping the position of the radiation source unchanged, controlling the stage and the detector to move step by step along the horizontal axis center line direction of the object to be measured to the target position, and controlling the detector to deflect to the first target angle along the vertical axis center line of the object to be measured, so as to obtain the corresponding movement trajectory parameter group. In this embodiment, according to 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 movement trajectory and their corresponding multiple step target positions can be preset in advance. When updating the movement trajectory of wafer tomography, as Figure 5As shown in (a) therein, the stage and the detector can be step - moved to each step - target position according to the preset step - target positions and order at each projection angle, and the horizontal axis coordinate (i.e., X - axis coordinate) of the stage center, the horizontal axis coordinate (i.e., X - axis coordinate) of the detector center position, 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) therein, 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 that the scanning multi - angle range set in the geometric parameter group is 80°, the number of projections is 36, and the starting angle is - 40°, then correspondingly, 36 projection angles can be obtained, and each projection angle is between - 40° and 40°. The 36 projection angles correspond to 36 step - target positions. When updating the motion trajectory of the wafer tomography according to the straight - line trajectory moving along the X - axis direction, a motion - trajectory parameter group composed of 36 groups of motion - trajectory parameters including the horizontal axis coordinate of the stage center, the horizontal axis coordinate of the detector center position, and the deflection angle of the detector along the vertical axis can be obtained.

[0061] When updating the motion trajectory of the wafer tomography according to the straight - line trajectory moving along the Y - axis direction, specifically: keeping the position of the radiation source unchanged, controlling the stage and the detector to be step - moved to the target position along the vertical axis central axis direction of the object to be measured and controlling the detector to be deflected to the second target angle along the horizontal axis central axis of the object to be measured to obtain the corresponding motion - trajectory parameter group. In this embodiment, according to 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 preset. When updating the motion trajectory of the wafer tomography, as Figure 5 shown in (b) therein, the stage and the detector can be step - moved to each step - target position according to the preset step - target positions and order 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) therein, P is the projection position of the target feature of the analyte, and (u, v) are the coordinates of the projection position. For example, assuming that the scanning multi-angle range set in the geometric parameter group is 90°, the number of projections is 36, and the starting angle is -45°, then correspondingly, 36 projection angles can be obtained, and each projection angle is between -45° and 45°. The 36 projection angles correspond to 36 step target positions. When updating the motion trajectory of the wafer tomography imaging according to the straight-line trajectory moving in the Y-axis direction, a motion trajectory parameter group composed of 36 sets of motion trajectory parameters including the longitudinal axis coordinates of the center of the stage, the longitudinal axis coordinates of the center position of the detector, and the deflection angle of the detector along the horizontal axis can be obtained.

[0062] When updating the motion trajectory of the wafer tomography imaging according to the circular trajectory, specifically: keeping the position of the radiation source unchanged, controlling the stage and the detector to move step by step to the target position along the horizontal axis central axis direction and the vertical axis central axis direction of the analyte respectively, and controlling the detector to deflect to the first target angle along the vertical axis central axis of the analyte and deflect to the second target angle along the horizontal axis central axis of the analyte, so as to obtain the corresponding motion trajectory parameter group. Exemplarily, according to 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 preset. When updating the motion trajectory of the wafer tomography imaging, such as Figure 5As shown in (c) therein, the stage and the detector can be stepped to each step target position according to the preset step target positions and order 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, assume that the source-object distance set in the geometric parameter group is 1.0544 mm, the source-image distance is 445.0630 mm, the scanning multi-angle 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 366.6443 mm, the starting stage center Y coordinate is 156.7327 mm, the detector center position X coordinate is 320.8168 mm, and the detector center position Y coordinate is 360.9374 mm. Correspondingly, 36 projection angles can be obtained, and each projection angle is between -40° and 40°. The 36 projection angles correspond to 36 step target positions. When updating the motion trajectory of the wafer tomography imaging according to the circular trajectory, 36 sets of motion trajectory parameter groups composed of motion trajectory parameters including the horizontal axis coordinate and vertical axis coordinate of the stage center, the horizontal axis coordinate and vertical axis coordinate of the detector center position, the deflection angle of the detector along the horizontal axis, and the deflection angle of the detector along the vertical axis can be obtained.

[0063] It can be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do 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 to the implementation process of the embodiments of the present application.

[0064] In some embodiments of the present application, please refer to Figure 6 , Figure 6 which is the basic structural block diagram of an on-line geometric correction device for wafer tomography imaging provided by the embodiments of the present application. In this embodiment, each unit included in the device is used to execute each step in the above method embodiment. For specific details, please refer to the relevant descriptions in the above method embodiment. For the sake of illustration, only the parts related to this embodiment are shown. As Figure 6As shown in the figure, the on-line geometric correction device for wafer tomography includes: an acquisition module 61, a calculation module 62, and a correction module 63. Among them: the acquisition module 61 is used to acquire the first projection image, the second projection image, and the third projection image of the target features of the object to be measured at different magnification factors when the line connecting the ray source focus and the center of the detector imaging plane is perpendicular to the detection plane. The calculation module 62 is used to calculate the corrected source-object distance and the corrected source-image distance according to the numerical relationship between the imaging parameters and the feature sizes reflected by the first projection image, the second projection image, and the third projection image respectively, where 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 features of the object to be measured. The correction module 63 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 the wafer tomography according to the geometric correction parameter group to obtain the corresponding motion trajectory parameter group, and save the geometric correction parameter group and the motion trajectory parameter group for wafer tomography.

[0065] It should be understood that the above on-line geometric correction device for wafer tomography corresponds one-to-one with the above on-line geometric correction method for wafer tomography, and will not be elaborated here.

[0066] In some embodiments of the present application, please refer to Figure 7 , Figure 7 which is a basic structural block diagram of an electronic device provided by an embodiment of the present application. As Figure 7 shown, the electronic device 7 in 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 the on-line geometric correction method of wafer tomography. When the processor 71 executes the computer program 73, the steps in each embodiment of the above on-line geometric correction method for wafer tomography are implemented. Or, when the processor 71 executes the computer program 73, the functions of each module in the corresponding embodiment of the above on-line geometric correction device for wafer tomography are implemented. For specific details, please refer to the relevant descriptions in the embodiments, and will not be elaborated here.

[0067] Exemplarily, the computer program 73 can be divided into one or more modules (units) for executing the steps in the above method embodiments. The one or more modules are stored in the memory 72 and executed by the processor 71 to complete the present application. The one or more modules can 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.

[0068] The electronic device may include, but is not limited to, a processor 71 and a memory 72. Those skilled in the art can understand thatFigure 7 This is only an example of the electronic device 7 and does not constitute a limitation on the electronic device 7. It may include more or fewer components than those shown in the figure, or combine certain components, or different components. For example, the electronic device may also include input / output devices, network access devices, buses, etc.

[0069] The processor 71 may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0070] The memory 72 may be an internal storage unit of the electronic device 7, such as the hard disk or memory of the electronic device 7. The memory 72 may also be an external storage device of the electronic device 7, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 7. Further, the memory 72 may also include both the internal storage unit and the external storage device of the electronic device 7. The memory 72 is used to store the computer program and other programs and data required by the electronic device. The memory 72 may also be used to temporarily store data that has been output or is to be output.

[0071] It should be noted that for the information interaction, execution process, etc. between the above-mentioned devices / units, since they are based on the same concept as the method embodiments of the present application, their specific functions and the technical effects brought about can be specifically referred to in the method embodiment part, and will not be elaborated here.

[0072] The embodiments of the present application also provide a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the steps in the above-mentioned method embodiments can be implemented. In this embodiment, the computer-readable storage medium may be non-volatile or volatile.

[0073] An embodiment of the present application provides a computer program product. When the computer program product runs on a mobile terminal, the mobile terminal can execute the steps in the above-mentioned method embodiments when executed.

[0074] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, only the above-mentioned division of each functional unit and module is used as an example. In actual applications, the above-mentioned functions can be allocated to different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated into a 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 a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of the present application. The specific working process of the units and modules in the above-mentioned device can refer to the corresponding process in the foregoing method embodiments and will not be elaborated here.

[0075] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, to implement all or part of the processes in the above-mentioned method embodiments of the present application, it can also be completed by a computer program instructing relevant hardware. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in the form of source code, object code, executable file or some intermediate form, etc. The computer-readable medium can include: any entity or device that can carry the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal, and software distribution medium, etc. It should be noted that the content included in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0076] In the above embodiments, the descriptions of each embodiment have their own emphases. For the parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0077] 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 foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included within the protection scope of the present application.

Claims

1. An online geometric correction method for wafer tomography, characterized in that, Including: When the line connecting the ray source focus and the center of the detector imaging plane is perpendicular to the detection plane, acquiring first projection images, second projection images, and third projection images of the target features of the object to be measured at different magnification factors; According to the numerical relationships between the imaging parameters and the feature sizes reflected by the first projection image, the second projection image, and the third projection image respectively, calculating the corrected source-object distance and the corrected source-image distance, where 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 features of the object to be measured; According to the corrected source-object distance and the corrected source-image distance, updating the geometric correction parameter group, and updating the motion trajectory of the wafer tomography imaging according to 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 imaging.

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

3. The online geometric correction method for wafer tomography according to claim 1, wherein The step of, according to the numerical relationships between the imaging parameters and the feature sizes reflected by the first projection image, the second projection image, and the third projection image respectively, calculating the corrected source-object distance and the corrected source-image distance includes: Calculating according to the numerical relationship between the imaging parameters and the feature sizes reflected in the first projection image in combination with the numerical relationship between the imaging parameters and the feature sizes reflected in the second projection image to obtain the corrected source-object distance; Calculating according to the corrected source-object distance in combination with the numerical relationship between the imaging parameters and the feature sizes reflected in the second projection image and the numerical relationship between the imaging parameters and the feature sizes reflected in the third projection image to obtain the corrected source-image distance.

4. The online geometric correction method for wafer tomography according to claim 1, characterized in that After the step of, according to the numerical relationships between the imaging parameters and the feature sizes reflected by the first projection image, the second projection image, and the third projection image respectively, calculating the corrected source-object distance and the corrected source-image distance, further includes: After adjusting the position of the detector or the ray source in the direction of the line connecting the ray source focus and the center of the detector imaging plane, acquiring a fourth projection image; Based on the fourth projection image, performing a verification process on 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 the preset accuracy conditions; If the corrected source object distance and the corrected source image distance do not meet the preset accuracy conditions, recalculate the corrected source object distance according to the preset source object distance calculation formula and recalculate the corrected source image distance based on the recalculated source object distance; Among them, the preset calibration formula is: ; SOD is the corrected source-object distance, SDD is the corrected source-image distance; ΔX4 is the projected 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, characterized in that, 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 magnification factors when the line connecting the ray source focus and the center of the detector imaging plane is perpendicular to the detection surface, the method further includes: Place the object to be measured on the stage, perform target detection on the object to be measured, and determine the target feature of the object to be measured; Collect the fifth projection image and the sixth projection image of the target feature of the object to be measured at different magnification factors; 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 ray source focus and the center of the detector imaging plane is perpendicular to the detection surface, where the plane direction includes the longitudinal axis center line direction and the transverse axis center line direction of the object to be measured.

6. The online geometric correction method for wafer tomography according to claim 5, wherein The step of 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 includes: Performing target detection on the object to be measured by moving the stage along a direction perpendicular to the stage plane to determine the target feature of the object to be measured; or Performing target detection on the object to be measured by performing dynamic perspective on the object to be measured to determine the target feature of the object to be measured.

7. The online geometric correction method for wafer tomography according to any one of claims 1-6, characterized in that The step of updating the motion trajectory of the wafer tomography imaging according to the geometric correction parameter group and obtaining the corresponding motion trajectory parameter group includes: Keeping the position of the ray source unchanged, controlling the stage and the detector to move step by step to a target position along the transverse axis center line direction of the object to be measured and controlling the detector to deflect to a first target angle along the longitudinal axis center line of the object to be measured 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 step by step to a target position along the longitudinal axis center line direction of the object to be measured and controlling the detector to deflect to a second target angle along the transverse axis center line of the object to be measured 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 step by step to the target positions along the transverse axis center line direction and the longitudinal axis center line direction of the object to be measured respectively and controlling the detector to deflect to the first target angle along the longitudinal axis center line of the object to be measured and deflect to the second target angle along the transverse axis center line of the object to be measured to obtain the corresponding motion trajectory parameter group.

8. An on-line geometric correction device for wafer tomography, characterized in that, including: An acquisition module, configured to collect 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 magnification factors when the line connecting the ray source focus 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 according to the numerical relationships between the imaging parameters and the feature sizes reflected by the first projection image, the second projection image, and the third projection image respectively, where 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, configured to update a geometric correction parameter set according to the corrected source object distance and the corrected source image distance, and update the motion trajectory of the wafer tomography imaging according to the geometric correction parameter set to obtain a corresponding motion trajectory parameter set, and save the geometric correction parameter set and the motion trajectory parameter set for wafer tomography imaging.

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

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