A double-side exposure wafer positioning method and device, electronic equipment and storage medium

Abstract

The application provides a double-side exposure wafer positioning method and device, electronic equipment and storage medium, and relates to the technical field of semiconductor manufacturing. The method comprises the following steps: receiving a reflected light signal and obtaining local Z-axis height information of the front and back surfaces of the wafer by analysis; controlling the axial movement of the upper and lower optical objectives according to the local Z-axis height information; after the optical focal plane adjustment is completed, obtaining a region image containing alignment marks on the front and back surfaces of the wafer, and identifying the geometric center coordinates of the alignment marks in the region image; calculating the alignment deviation between the front and back surfaces of the wafer according to the geometric center coordinates of the alignment marks; and controlling the movement or rotation of the workbench to compensate for the deviation according to the alignment deviation. The method of the application aims to solve the technical problem of actual alignment error of wafer front and back surface patterns, can significantly improve the recognition accuracy of alignment marks, and thus realize accurate alignment of wafer front and back surface patterns, overcoming the limitations of traditional methods in dealing with wafer topography changes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, and in particular, to a double-side exposure wafer positioning method and device, an electronic device and a storage medium. BACKGROUND

[0002] In the field of semiconductor manufacturing, especially for the production of devices that require accurate alignment of front and back patterns, zero-flip double-side alignment technology is favored for its high efficiency and low risk of contamination. This technology acquires front and back wafer images simultaneously through a double-view optical system and identifies alignment marks to achieve accurate alignment. However, in actual production, wafers are not always ideal flat rigid bodies, and they may have geometric deviations such as warping or uneven thickness. These deviations can cause the double-view optical system to be out of focus when acquiring front and back wafer images, which in turn affects the recognition accuracy of the alignment marks, ultimately leading to actual alignment errors of front and back patterns. Traditional alignment methods often fail to effectively address the out-of-focus problem caused by changes in the wafer's own morphology, thus limiting the application range and accuracy of zero-flip double-side alignment technology.

[0003] Specifically, in the manufacturing process of semiconductor devices, especially micro-electro-mechanical systems (MEMS), power devices or three-dimensional integrated circuits, double-side lithography is a key process. It requires the fabrication of circuit patterns on both the front and back surfaces of the wafer, and the alignment accuracy between the patterns on the front and back surfaces must be extremely high. Traditional process methods require first completing one side of the lithography, then removing the wafer from the equipment, physically flipping it with a mechanical hand, and then sending it back into the equipment for alignment and exposure on the other side. This flipping process not only prolongs the production cycle and increases the risk of wafer contamination by particles, but also introduces uncontrollable alignment errors due to mechanical handling and repositioning, directly affecting the performance and yield of the final device.

[0004] To solve these problems, the industry has developed a zero-flip double-sided alignment technology. The core of this technology is a precise double-view optical system, which is integrated under and above the worktable of the lithography machine. When the wafer is placed on the worktable, the optical components above directly observe the front side of the wafer, and the optical components below can "penetrate" the specific through-hole of the worktable through a complex combination of beam splitters and mirrors to observe the back side of the wafer. In this way, the control system can simultaneously obtain real-time images of the front and back sides of the wafer. When performing alignment, the system will look for pre-set alignment marks, which are usually special patterns such as crosses or squares, in the front and back images respectively. After receiving the two video signals, the image processing unit accurately calculates the center coordinates of each mark through a specific recognition program. Then, the system compares the coordinates of the front and back marks in the same reference coordinate system and calculates the translation and rotation deviation between them. Finally, by driving the high-precision piezoelectric ceramic worktable to make small movements and rotations, the deviation is compensated until the front and back marks completely coincide in the superimposed image, thus completing the high-precision double-sided alignment. The entire process does not require the wafer to be flipped, greatly improving efficiency and alignment accuracy.

[0005] However, this idealized working mode is based on the premise that the wafer is a rigid plane with absolutely uniform thickness and absolutely flat surface. In actual production environment, this premise is often not true. Due to internal stress introduced during wafer growth, slicing, grinding and subsequent heat treatment, the wafer itself will warp to a certain extent and is no longer a perfect plane. At the same time, the thickness of the wafer may also vary by microns, i.e. total thickness variation (TTV). When such a wafer with geometric morphology deviation is placed on the worktable, problems will follow. The optical focal planes of the upper and lower optical components of the dual-view optical system are pre-set during the device debugging stage, and this setting is based on a standard thickness flat wafer. For a warped wafer, the actual working distance between the wafer surface and the upper and lower optical objectives will change when the worktable moves to different positions to capture different alignment marks. For example, in the edge region of the wafer, due to upward warping, its upper surface will be closer to the upper optical objective, while its lower surface will be farther away from the lower optical objective. This deviation in working distance directly leads to defocusing of the optical system. The direct consequence of defocusing is that the alignment mark image captured by the camera becomes blurred, and the edges of the mark are no longer sharp and clear, but show a diffuse transition zone. The image processing program responsible for identifying the mark position is based on edge detection or gray centroid calculation to determine the geometric center of the mark. When a blurred edge image is input, the calculation accuracy of the program will decrease significantly. The mark center position calculated by it will deviate from its actual physical center position, resulting in a measurement error. More troublesome is that due to the asymmetric nature of wafer warping, the defocusing experienced by the upper optical system and the lower optical system at the same observation point is likely to be different. For example, the upper image may be slightly blurred, while the lower image may be severely blurred. This leads to inconsistent position measurement errors of the upper and lower marks. The system ultimately calculates the relative deviation between the front and back surfaces based on these two measurement values with different errors, and this calculation result itself contains a false deviation amount. The system drives the worktable to "correct" according to this erroneous result, which is actually an erroneous movement, ultimately resulting in an alignment error between the front and back patterns after lithography that should not have existed. This error is implicit because at the alignment system level, it shows that the alignment is complete, but the physical misalignment has already been cast, seriously affecting the yield of the chip.

[0006] There is currently no effective technical solution to the above problems. SUMMARY

[0007] The purpose of the present application is to provide a double-sided exposure wafer positioning method, device, electronic equipment and storage medium, aiming to solve the technical problem that in the existing zero-flip double-sided alignment technology, the defocus caused by the geometric appearance deviation of wafer warping or uneven thickness affects the alignment mark recognition accuracy, and finally leads to the actual alignment error of front and back patterns, which can significantly improve the recognition accuracy of alignment marks, so as to realize the accurate alignment of wafer front and back patterns, and overcome the limitations of traditional methods in dealing with wafer appearance changes.

[0008] In a first aspect, the present application provides a double-sided exposure wafer positioning method, comprising the following steps:

[0009] S1. Control the double-view optical system to emit a detection light beam to the upper optical channel and the lower optical channel respectively, and receive the reflection light signals of the respective reflected light;

[0010] S2. Obtain the local Z-axis height information of the front and back surfaces of the wafer by analyzing the reflection light signals;

[0011] S3. According to the local Z-axis height information, control the axial movement of the upper and lower optical objectives to adjust the respective optical focal plane to the corresponding specified Z-axis height, so that the optical focal plane of each optical objective is accurately coincided with the vertical height position of the alignment mark to be observed on the front and back surfaces of the wafer;

[0012] S4. After the optical focal plane is adjusted, obtain the area image containing the alignment marks on the front and back surfaces of the wafer, and identify the geometric center coordinates of the alignment marks in the area image;

[0013] S5. Calculate the alignment deviation between the front and back surfaces of the wafer according to the geometric center coordinates of the alignment marks;

[0014] S6. According to the alignment deviation, control the movement or rotation of the workbench to compensate for the deviation.

[0015] The double-sided exposure wafer positioning method provided by the present application effectively solves the defocus problem caused by the geometric appearance deviation of wafer warping or uneven thickness in the existing zero-flip double-sided alignment technology by introducing the accurate acquisition of local Z-axis height information of the front and back surfaces of the wafer and the self-adaptive adjustment mechanism of the optical focal plane, and provides a more accurate and reliable zero-flip double-sided alignment solution for the semiconductor manufacturing field.

[0016] In a second aspect, the present application provides a double-sided exposure wafer positioning device, comprising:

[0017] A first control module for controlling the double-view optical system to emit a detection light beam to the upper optical channel and the lower optical channel respectively, and receiving the reflection light signals of the respective reflected light;

[0018] an analysis module configured to obtain local Z-axis height information of the front and back surfaces of the wafer by analyzing the reflected light signal;

[0019] a second control module configured to control axial movement of the upper and lower optical objectives according to the local Z-axis height information, so as to adjust the respective optical focal planes to the corresponding specified Z-axis height, so that the optical focal plane of each optical objective is accurately coincided with the vertical height position of the alignment mark to be observed on the front and back surfaces of the wafer;

[0020] a recognition module configured to obtain a region image containing the alignment marks on the front and back surfaces of the wafer after the optical focal plane is adjusted, and recognize the geometric center coordinates of the alignment marks in the region image;

[0021] a calculation module configured to calculate the alignment deviation between the front and back surfaces of the wafer according to the geometric center coordinates of the alignment marks;

[0022] a third control module configured to control movement or rotation of the worktable to compensate for the deviation according to the alignment deviation.

[0023] In a third aspect, the present application provides an electronic device comprising a processor and a memory, wherein the memory stores computer readable instructions, and when the computer readable instructions are executed by the processor, the steps of the double-sided exposure wafer positioning method provided in the first aspect are executed.

[0024] In a fourth aspect, the present application provides a computer readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the steps of the double-sided exposure wafer positioning method provided in the first aspect are executed.

[0025] As can be seen from the above, the double-sided exposure wafer positioning method provided by the present application can effectively compensate for the defocus caused by wafer warping and uneven thickness by real-time acquisition of local Z-axis height information of the front and back surfaces of the wafer and dynamic adjustment of the optical focal plane of the optical objective, ensure the clarity of the alignment mark image, and overcome the limitations of the traditional method in dealing with wafer topography changes. In addition, due to the significant improvement in the clarity of the alignment mark image, the image processing program can more accurately recognize the geometric center coordinates of the mark, thereby greatly reducing the measurement error and avoiding false deviation calculation caused by defocus. Finally, higher front and back surface pattern alignment accuracy is achieved. Furthermore, the present application can adapt to wafers with different topography characteristics, reduce alignment failure or precision reduction caused by individual differences of wafers, improve the applicability and reliability of the zero-flip double-sided alignment technology in actual production, and finally effectively avoid pattern misalignment after lithography, thereby directly improving the production yield of chips and reducing the manufacturing cost.

[0026] Other features and advantages of the present application will be set forth in the description that follows, and in part will be apparent from the description, or can be learned by practice of the application. The purposes and other advantages of the present application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A flow chart of a double-side exposure wafer positioning method provided by an embodiment of the present application.

[0028] Figure 2 A structural schematic diagram of a double-side exposure wafer positioning device provided by an embodiment of the present application.

[0029] Figure 3 A structural schematic diagram of an electronic device provided by an embodiment of the present application.

[0030] KEY

[0031] 100, first control module; 200, analysis module; 300, second control module; 400, identification module; 500, calculation module; 600, third control module; 13, electronic device; 1301, processor; 1302, memory; 1303, communication bus. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0033] It should be noted that: similar labels and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. Meanwhile, in the description of the present application, the terms “first”, “second” and the like are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0034] Please refer to Figure 1 , Figure 1 is a flow chart of a double-side exposure wafer positioning method. The double-side exposure wafer positioning method comprises the following steps:

[0035] S1. The dual-view optical system controls the emission of a probe light beam to the upper optical channel and the lower optical channel, respectively, and receives the reflected light signals of the respective reflected light;

[0036] S2. By analyzing the reflected light signals, local Z-axis height information of the front and back surfaces of the wafer is obtained;

[0037] S3. According to the local Z-axis height information, the axial movement of the upper and lower optical objectives is controlled to adjust the respective optical focal plane to the corresponding specified Z-axis height, so that the optical focal plane of each optical objective is accurately coincided with the vertical height position of the alignment mark to be observed on the front and back surfaces of the wafer;

[0038] S4. After the optical focal plane adjustment is completed, the area image containing the alignment marks on the front and back surfaces of the wafer is obtained, and the geometric center coordinates of the alignment marks in the area image are identified;

[0039] S5. According to the geometric center coordinates of the alignment marks, the alignment deviation between the front and back surfaces of the wafer is calculated;

[0040] S6. According to the alignment deviation, the workbench is controlled to move or rotate to compensate for the deviation.

[0041] The present application aims to solve the defocusing problem caused by the geometric topography deviation of the wafer in the prior art, thereby improving the positioning accuracy of the double-sided exposure wafer. By introducing the mechanism of obtaining the local Z-axis height information of the front and back surfaces of the wafer and adjusting the optical focal plane, the present application can ensure that the optical system is always in the best focusing state under different wafer topography conditions, thereby accurately identifying the alignment marks and ultimately achieving high-precision alignment compensation.

[0042] In this application, "dual-view optical system" refers to an optical device capable of observing and acquiring images of both the front and back surfaces of a wafer simultaneously. This system typically includes an upper optical channel and a lower optical channel, which are used to detect the front and back surfaces of the wafer, respectively. The "upper optical channel" is usually composed of a set of lenses, mirrors, and detectors located above the wafer, used to directly observe the front surface of the wafer; the "lower optical channel" usually uses a complex combination of beam splitters and mirrors to enable the optical components located below the wafer to observe the back surface of the wafer. These two channels work together to ensure that information from both the front and back surfaces of the wafer can be acquired simultaneously during a single positioning process. The "probe light beam" refers to the light emitted by the dual-view optical system to illuminate the wafer, and the "reflected light signal" returned by its reflection carries the height and topography information of the wafer surface. The "optical objective" is a key component of the dual-view optical system, responsible for focusing the image of the wafer surface onto the detector. The "optical focal plane" is the plane where the optical objective can clearly image, and its accurate adjustment is crucial for obtaining a clear alignment mark image. The "alignment mark" is a specific geometric pattern pre-made on the front and back surfaces of the wafer, used as a reference point during alignment. The "geometric center coordinates" refer to the precise position of the alignment mark in the image, usually calculated by image processing algorithms. The "worktable" is a mechanical device used to carry and accurately move the wafer, and its movement or rotation is used to compensate for the alignment deviation between the front and back surfaces of the wafer.

[0043] In specific implementation, the dual-side exposure wafer positioning method first controls the dual-view optical system to emit probe light beams to the upper optical channel and the lower optical channel, respectively, and receives the reflected light signals of the respective reflected light in step S1. The probe light beam can be a laser beam, a broadband light beam, or a LED light beam of a specific wavelength. For example, a confocal laser scanning system can be used to scan the wafer surface with a laser beam and receive the reflected light signal. The reception of the reflected light signal can be achieved by a photodetector, a CCD or CMOS sensor array.

[0044] Subsequently, in step S2, the local Z-axis height information of the front and back surfaces of the wafer is obtained by analyzing the reflected light signal. The analysis of the reflected light signal can use various techniques. For example, the height information of the wafer surface can be inferred by analyzing the intensity, phase or time of flight of the reflected light signal. One implementation is to use the confocal principle to find the Z-axis position corresponding to the maximum intensity as the local height by scanning different Z-axis heights and recording the reflected light intensity. Another implementation is to use interference measurement technology to accurately calculate the height of the wafer surface by analyzing the interference fringes between the reflected light and the reference light.

[0045] Next, in step S3, according to the local Z-axis height information, the axial movement of the upper and lower optical objectives is controlled to adjust the respective optical focal planes to the corresponding specified Z-axis height, so that the optical focal plane of each optical objective is accurately coincided with the vertical height position of the alignment mark to be observed on the front and back surfaces of the wafer. The axial movement of the optical objective can be achieved by a high-precision actuator such as a piezoelectric ceramic driver, a voice coil motor or a stepper motor. For example, according to the local Z-axis height information obtained in step S2, the average Z-axis height of each alignment mark area can be calculated, and then the average height is taken as the specified Z-axis height, and the optical objective is driven to move to this position.

[0046] After the optical focal plane adjustment is completed, step S4 acquires a region image containing the alignment marks on the front and back surfaces of the wafer, and identifies the geometric center coordinates of the alignment marks in the region image. The acquisition of the region image can be completed by a high-resolution CCD or CMOS camera. The identification of the alignment mark can use an image processing algorithm, for example, an edge detection algorithm (such as Canny, Sobel operator), a template matching algorithm or an image recognition algorithm based on deep learning. For example, the image can be binarized first, and then the alignment mark area is found by using connected component analysis, and the geometric center coordinates are determined by calculating the centroid of the area.

[0047] Next, in step S5, the alignment deviation between the front and back surfaces of the wafer is calculated according to the geometric center coordinates of the alignment marks. The calculation of the alignment deviation can be based on the principle of geometric transformation. For example, the least squares method or the iterative closest point (ICP) algorithm can be used to calculate the translation and rotation transformation parameters by matching the alignment mark point sets on the front and back surfaces of the wafer, so as to obtain the alignment deviation.

[0048] Finally, in step S6, according to the alignment deviation, the movement or rotation of the workbench is controlled to compensate for the deviation. The movement and rotation of the workbench can be achieved by a high-precision piezoelectric ceramic workbench, a linear motor or a rotary motor. For example, if the calculated alignment deviation includes translation in X and Y directions and rotation in Z-axis direction, the workbench can be driven to move in micron level in X and Y directions, and to rotate in micro-radian level around Z-axis, so as to eliminate the deviation.

[0049] The double-sided exposure wafer positioning method of the present application effectively solves the defocusing problem caused by the geometric profile deviation of the wafer in the prior art by introducing the accurate acquisition of the local Z-axis height information of the front and back surfaces of the wafer and the adaptive adjustment mechanism of the optical focal plane. In the traditional method, due to the warping or uneven thickness of the wafer, the optical focal plane of the optical system cannot be accurately coincided with the wafer surface, resulting in blurred alignment mark image, reduced recognition accuracy, and further introduced alignment error.

[0050] The application first utilizes the dual-view optical system to emit a probe light beam and receive a reflected light signal in steps S1 and S2, and then analyzes the signals to obtain local Z-axis height information of the front and back surfaces of the wafer. This process can accurately perceive the actual topography of the wafer surface, rather than relying on a preset ideal plane. Subsequently, in step S3, according to the real-time local Z-axis height information, the system can intelligently control the two optical objectives to move axially, and accurately adjust the respective optical focal planes to coincide with the vertical height position of the alignment mark to be observed. Thus, regardless of how uneven the wafer surface is, the optical system can always be in the best focus state when the alignment mark image is acquired.

[0051] After the optical focal plane adjustment is completed, step S4 acquires a clear alignment mark area image and accurately identifies the geometric center coordinates of the alignment mark. Since the image clarity is guaranteed, the accuracy of mark identification is also greatly improved. Then, step S5 calculates the real alignment deviation between the front and back surfaces of the wafer according to the high-precision geometric center coordinates. Finally, in step S6, the system accurately controls the movement or rotation of the worktable according to the calculated alignment deviation, thereby realizing effective compensation for the deviation.

[0052] Compared with the prior art, the core innovation of the application lies in its adaptive optical focal plane adjustment capability. Traditional methods usually adopt a fixed optical focal plane or a simple global Z-axis adjustment, which is difficult to cope with the complex changes in the local topography of the wafer. The application acquires the local Z-axis height information of the front and back surfaces of the wafer in real time, and dynamically adjusts the optical focal plane of the optical objective according to the information, thereby ensuring the clarity and identification accuracy of the alignment mark image on the entire wafer surface. This method can significantly reduce the alignment error caused by the wafer topography deviation, thereby improving the alignment accuracy of double-sided exposure and the yield of chips. For example, when processing a wafer with a 5-micron local warping, the traditional method may cause the alignment mark image to be severely out of focus, with an identification error of hundreds of nanometers. However, the application can control the out-of-focus error to be sub-micron or even nanometer level through accurate optical focal plane adjustment, thereby reducing the alignment error by an order of magnitude.

[0053] In some embodiments, the specific steps in step S2 include:

[0054] S21. Acquire the preliminary Z-axis height range of the front and back surfaces of the wafer by analyzing the reflected light signal;

[0055] S22. Control the optical objective to scan along the Z-axis within the corresponding preliminary Z-axis height range, and collect a corresponding series of scanning images during the scanning process;

[0056] S23. Evaluate the sharpness of the scanned image and take the Z-axis height position corresponding to the scanned image with the best sharpness as the corresponding local Z-axis height information to obtain the local Z-axis height information of the front and back sides of the calibrated wafer.

[0057] Specifically, in step S21, by performing preliminary analysis on the reflected light signals received by the dual-field optical system, the approximate vertical height regions of the front and back sides of the wafer, i.e., the preliminary Z-axis height range, can be quickly determined. This preliminary range aims to narrow the search space for subsequent fine scanning and improve efficiency. Further, in step S22, once the preliminary Z-axis height range is determined, the optical objective lens is precisely controlled to move axially along the Z-axis within this preliminary Z-axis height range, continuously or discretely acquiring a series of scan images during this process. These scan images record the visual information of the wafer surface at different Z-axis height positions. Subsequently, in step S23, the sharpness of the acquired scan images is evaluated. Sharpness evaluation can be achieved through various image processing algorithms, such as calculations based on gradient, contrast, edge sharpness, or frequency domain energy. By comparing the sharpness of these scan images, the image with the best sharpness can be accurately identified, and the Z-axis height position corresponding to this image is determined as the local Z-axis height information of the front and back sides of the wafer. Thus, calibrated, high-precision local Z-axis height information of the front and back sides of the wafer is obtained.

[0058] This application's solution effectively addresses the problems of insufficient accuracy, susceptibility to environmental noise, and insensitivity to minute undulations on the wafer surface faced by traditional methods when directly acquiring high-precision local Z-axis height information. These problems are addressed by introducing a preliminary Z-axis height range determination, fine Z-axis scanning with optical objectives, and a clarity evaluation mechanism for the scanned images. First, obtaining the preliminary Z-axis height range allows subsequent fine scanning to be performed in a smaller, more relevant space, significantly improving scanning efficiency and reducing computational burden. Second, by systematically scanning the Z-axis within the preliminary height range and acquiring a series of images, detailed information about the wafer surface at different vertical heights is ensured to be fully captured. Finally, optical focal plane determination based on image clarity leverages the physical characteristic that images have the highest clarity at the focal point. Through objective image processing algorithms rather than simple signal thresholding, the precise vertical height position of the wafer's front and back alignment marks can be identified more accurately and robustly, overcoming the noise interference and uncertainties that may exist with single reflected light signals.

[0059] By the technical solution, the acquisition accuracy and reliability of the local Z-axis height information of the front and back surfaces of the wafer can be significantly improved. The method refines in steps, from preliminary range determination to fine scanning, and then to accurate judgment based on image clarity, effectively avoiding errors that may be caused by directly analyzing the reflected light signal, and ensuring the accuracy of subsequent optical focus plane adjustment of the optical objective. Thus, a solid foundation is laid for clear imaging and accurate identification of the alignment marks on the front and back surfaces of the wafer, and the overall precision and stability of the double-side exposure wafer positioning are ultimately improved.

[0060] In some embodiments, the specific steps in step S21 include:

[0061] S211. Preprocessing the reflected light signal to obtain a preprocessed reflected light signal;

[0062] S212. Acquiring a preliminary Z-axis height range of the front and back surfaces of the wafer by analyzing the preprocessed reflected light signal.

[0063] Specifically, the preprocessing includes removing transient outliers and performing local smoothing processing to suppress local fluctuations and false peaks caused by random contaminants or local roughness unevenness.

[0064] The scheme of the present application effectively solves the noise and instability problems existing in the original signal by removing transient outliers and performing local smoothing processing on the reflected light signal. Specifically, removing transient outliers can eliminate discrete, high-amplitude error data points caused by accidental interference (such as contaminants). If these data points are not removed, they may be incorrectly identified as real height features of the wafer surface, or cause significant deviations in the calculation of the preliminary Z-axis height range. At the same time, local smoothing processing suppresses random noise and slight fluctuations caused by surface microstructure that exist universally in the signal, making the overall trend of the signal clearer and helping to distinguish real height changes from noise interference. It is due to the synergistic effect of the two kinds of processing that the preprocessed reflected light signal can more accurately reflect the actual height information of the front and back surfaces of the wafer, thereby laying a solid foundation for subsequent accurate acquisition of the preliminary Z-axis height range.

[0065] By the technical solution, the accuracy and reliability of obtaining the preliminary Z-axis height information of the front and back surfaces of the wafer can be significantly improved. Specifically, by removing the instantaneous outliers, the erroneous height judgment caused by random contaminants or measurement instantaneous interference can be effectively avoided; by local smoothing processing, the signal fluctuation caused by the local roughness unevenness of the wafer surface or system noise can be inhibited, so that the identification of the preliminary Z-axis height range is more stable and accurate. This improvement not only enhances the robustness of the system to complex wafer surface conditions and environmental noise, but also provides a more accurate reference for subsequent optical objective lens optical focal plane adjustment, ultimately helping to improve the overall accuracy and efficiency of the double-side exposure wafer positioning.

[0066] In some embodiments, the specific steps in step S5 include:

[0067] S51. Point set matching is performed on the geometric center coordinates of the alignment marks to obtain a corresponding point set;

[0068] S52. Based on the corresponding point set, translation transformation parameters and / or rotation transformation parameters that minimize the distance residual between the corresponding point set are calculated;

[0069] S53. According to the translation transformation parameters and / or rotation transformation parameters, the alignment deviation between the front and back surfaces of the wafer is calculated.

[0070] Point set matching refers to establishing a corresponding relationship between the alignment marks on the front and back surfaces of the wafer by a specific algorithm. For example, a matching algorithm based on feature descriptors, an iterative closest point (ICP) algorithm, or a matching method based on topological structure analysis can be used to ensure that the same alignment marks on the front and back surfaces are accurately associated, thereby forming a corresponding point set.

[0071] Further, based on the obtained corresponding point set, transformation parameters that can describe the relative positional relationship between the front and back surfaces of the wafer need to be calculated. These parameters include translation transformation parameters and / or rotation transformation parameters. The translation transformation parameters are used to describe the relative displacement of the wafer in the X and Y directions, while the rotation transformation parameters are used to describe the relative rotation of the wafer in the Z-axis direction. The goal of calculating these parameters is to minimize the distance residual between the corresponding point set, which means that through these transformation parameters, the alignment mark points on the front surface of the wafer can be accurately mapped to the corresponding alignment mark points on the back surface of the wafer as much as possible, thereby minimizing the deviation between them.

[0072] Thus, after obtaining the translation transformation parameters and / or rotation transformation parameters, the alignment deviation between the front and back surfaces of the wafer can be calculated according to these parameters. This alignment deviation can be a comprehensive value, such as the average deviation, the maximum deviation, or a vector containing translation and rotation components, to accurately quantify the degree of misalignment between the front and back surfaces of the wafer.

[0073] The scheme of the present application realizes accurate quantification of the relative position relationship between the front and back surfaces of the wafer by refining the step S5 of calculating the alignment deviation between the front and back surfaces of the wafer into three sub-steps of point set matching, transformation parameter calculation and deviation calculation. First, through point set matching, the alignment marks on the front and back surfaces of the wafer are ensured to be accurately associated, laying a foundation for subsequent deviation calculation. Second, by calculating the translation transformation parameters and / or rotation transformation parameters that minimize the distance residual between the corresponding point sets, the overall translation and rotation deviation between the front and back surfaces of the wafer can be effectively captured, avoiding errors that may be caused by only based on a single marker point or simple difference calculation. It is precisely due to this overall point set optimization method that the calculated transformation parameters can more accurately reflect the actual alignment relationship between the front and back surfaces of the wafer. Finally, according to these accurate transformation parameters, the alignment deviation between the front and back surfaces of the wafer can be reliably calculated, providing accurate basis for subsequent deviation compensation.

[0074] Through the above technical scheme, accurate and robust calculation of the alignment deviation between the front and back surfaces of the wafer can be realized. The introduction of point set matching ensures the accuracy of the corresponding relationship of the alignment marks, avoiding calculation errors caused by misidentification or local defects. The transformation parameter calculation method based on distance residual minimization can effectively suppress the influence of measurement noise and local non-uniformity on deviation calculation, thereby improving the accuracy and stability of deviation calculation. Thus, the scheme of the present application can provide more reliable positioning data for the double-sided exposure process, thereby improving the accuracy and yield of exposure alignment.

[0075] In some embodiments, the specific steps in step S52 include:

[0076] S521. Based on the corresponding point sets, translation transformation parameters and / or rotation transformation parameters are calculated by least squares method.

[0077] The scheme of the present application can effectively solve the problems of low efficiency, insufficient accuracy or sensitivity to noise that may occur in traditional methods when the specific calculation method is not explicitly specified, by introducing the least squares method to calculate the translation transformation parameters and / or rotation transformation parameters. The least squares method can extract the most reliable transformation parameters from the data containing measurement errors by systematically minimizing the sum of squares of distance residuals between all corresponding point pairs. This method has good mathematical properties and can provide an optimal linear unbiased estimate, thereby ensuring that the calculated translation transformation parameters and / or rotation transformation parameters have high accuracy and stability. Thus, even in the case of local defects on the wafer surface or minor errors in alignment mark recognition, accurate alignment deviation information can be obtained.

[0078] By the above technical solution, the translation transformation parameter and / or the rotation transformation parameter are calculated by the least square method, which significantly improves the accuracy and robustness of the calculation of the alignment deviation between the front and back surfaces of the wafer. Compared with other possible simple calculation methods, the least square method can effectively suppress the influence of random errors and noise on the calculation results, ensuring that the obtained transformation parameters are closer to the true values. This is crucial for the strict requirements of alignment accuracy in the double-sided exposure process, effectively reducing the yield loss caused by positioning errors, thereby improving overall production efficiency and product quality.

[0079] In some preferred embodiments, assuming that a set of alignment mark geometric center coordinates of the front surface of the wafer P_front={(x_f1,y_f1),...,(x_fn,y_fn)} and a set of corresponding alignment mark geometric center coordinates of the back surface of the wafer P_back={(x_b1,y_b1),...,(x_bn,y_bn)} are obtained in step S4, where P_front is the alignment mark geometric center coordinates of the front surface of the wafer, x_f1 is the x-axis coordinate of the 1st alignment mark geometric center of the front surface of the wafer, y_f1 is the y-axis coordinate of the 1st alignment mark geometric center of the front surface of the wafer, x_fn is the x-axis coordinate of the n th alignment mark geometric center of the front surface of the wafer, y_fn is the y-axis coordinate of the n th alignment mark geometric center of the front surface of the wafer, P_back is the alignment mark geometric center coordinates of the back surface of the wafer, x_b1 is the x-axis coordinate of the 1st alignment mark geometric center of the back surface of the wafer, y_b1 is the y-axis coordinate of the 1st alignment mark geometric center of the back surface of the wafer, x_bn is the x-axis coordinate of the n th alignment mark geometric center of the back surface of the wafer, and y_bn is the y-axis coordinate of the n th alignment mark geometric center of the back surface of the wafer. In step S51, these point sets are matched to establish a correspondence. Subsequently, in step S521, in order to calculate the translation transformation parameters (Δx, Δy) and the rotation transformation parameters (θ), an error function E can be constructed, for example, E=Σ[(x_bi-(x_fi*cosθ-y_fi*sinθ+Δx))^2+(y_bi-(x_fi*sinθ+y_fi*cosθ+Δy))^2]. By taking the partial derivatives of this error function E with respect to Δx, Δy, and θ and setting them to zero, a set of equations can be obtained. These equations can be solved by an iterative optimization algorithm (such as the Levenberg-Marquardt algorithm) or analytically under certain conditions, thereby obtaining the optimal translation transformation parameters and rotation transformation parameters that minimize the sum of squared errors. For example, when only considering translation transformation, Δx and Δy can be preliminarily estimated by simply calculating the average difference between the X and Y coordinates of the corresponding point sets, and then refined by the least square method. When rotation is considered, more complex matrix operations and iterative solution processes are required to accurately determine the rotation angle and center, ensuring that the calculation of the alignment deviation reaches the sub-micron accuracy requirement.

[0080] In some embodiments, the specific steps in step S53 include:

[0081] S531. Transform the geometric center coordinates of all alignment marks on the wafer front side to the wafer back side coordinate system through translation transformation parameters and / or rotation transformation parameters to obtain transformed wafer front side mark points;

[0082] S532. Calculate the average distance or maximum distance between the transformed wafer front side mark points and the corresponding mark points on the wafer back side;

[0083] S533. Take the average distance or maximum distance as the alignment deviation between the wafer front and back sides.

[0084] Specifically, in step S531, the geometric center coordinates of all alignment marks on the wafer front side are regarded as a point set, and this point set is converted from the wafer front side coordinate system to the wafer back side coordinate system through the translation transformation parameters and / or rotation transformation parameters obtained in step S52. The purpose of this transformation is to simulate the positions of the wafer front side mark points in the wafer back side coordinate system under ideal alignment conditions, so as to facilitate comparison with the actual wafer back side mark points. The transformed point set is referred to as the transformed wafer front side mark points.

[0085] In step S532, after obtaining the transformed wafer front side mark points, they need to be compared with the corresponding alignment mark points on the wafer back side. This comparison can be done by calculating the distance between them. Specifically, the Euclidean distance between each pair of corresponding mark points can be calculated, and then these distances are statistically analyzed. The average distance is the arithmetic mean of the distances between all pairs of corresponding mark points, which can reflect the overall alignment. The maximum distance is the maximum value among all pairs of corresponding mark points, which can reveal the most serious local alignment deviation.

[0086] In practical applications, step S533 takes the average distance or maximum distance calculated above as the alignment deviation between the wafer front and back sides. The choice of average distance or maximum distance as the quantitative indicator of deviation depends on the specific application scenario and the requirement for positioning accuracy. For example, when the overall alignment accuracy is required to be high, the average distance may be more suitable; while when it is necessary to ensure that the deviation of any local area does not exceed a certain threshold, the maximum distance is more critical. The purpose is to provide a quantitative and operable alignment deviation value for subsequent deviation compensation operations.

[0087] The scheme of the present application eliminates the error caused by the inconsistency of the coordinate systems by first transforming the wafer front side mark points to the wafer back side coordinate system, so that the two point sets are compared in the same reference system. Subsequently, the inconsistency between the two is directly quantified by calculating the distance between the transformed wafer front side mark points and the corresponding mark points on the wafer back side. This distance-based quantification method is intuitive and accurate, and can effectively reflect the actual alignment deviation between the wafer front and back sides. Whether the average distance or the maximum distance is used, it provides a clear numerical basis for subsequent deviation compensation, ensuring the accuracy and effectiveness of the compensation.

[0088] Through the above technical scheme, the present application can provide an accurate and reliable quantification method for the alignment deviation between the wafer front and back sides. Compared with only obtaining the translation and rotation transformation parameters, the present scheme further converts these parameters into intuitive distance deviations, making the evaluation of the alignment deviation more specific and operable. This helps to improve the accuracy and stability of wafer positioning in the double-side exposure process, reduce the scrap rate caused by inaccurate alignment, and thus improve production efficiency and product quality.

[0089] In some preferred embodiments, it is assumed that the wafer front side has four alignment mark points P1, P2, P3, P4, and their geometric center coordinates are (x1, y1), (x2, y2), (x3, y3), (x4, y4), respectively. The wafer back side has four corresponding alignment mark points Q1, Q2, Q3, Q4, and their geometric center coordinates are (X1, Y1), (X2, Y2), (X3, Y3), (X4, Y4), respectively.

[0090] First, the translation transformation parameters (Δx, Δy) and the rotation transformation parameter θ of transforming the front side mark points to the back side coordinate system are obtained by point set matching and least squares method.

[0091] Next, the coordinates of the front side mark points P1, P2, P3, P4 are transformed by these parameters to obtain the transformed wafer front side mark points P'1, P'2, P'3, P'4, whose coordinates are (x'1, y'1), (x'2, y'2), (x'3, y'3), (x'4, y'4), respectively.

[0092] Then, the Euclidean distance between each pair of corresponding mark points is calculated:

[0093] d1 = distance (P'1, Q1);

[0094] d2 = distance (P'2, Q2);

[0095] d3 = distance (P'3, Q3);

[0096] d4 = distance (P'4, Q4);

[0097] Finally, the average of these distances (d1+d2+d3+d4) / 4 can be calculated as the average distance deviation, or max{d1,d2,d3,d4} can be taken as the maximum distance deviation. For example, if the average distance is 0.5 microns, then 0.5 microns is taken as the alignment deviation between the front and back surfaces of the wafer, which is used to guide the worktable to make corresponding translation or rotation compensation.

[0098] Please refer to Figure 2 , Figure 2 is a double-side exposure wafer positioning device in some embodiments of the present application, which is integrated in a back-end control device in the form of a computer program, comprising:

[0099] a first control module 100, configured to control the double-view optical system to emit a detection light beam to the upper optical channel and the lower optical channel respectively, and receive reflection light signals of the respective reflected light;

[0100] an analysis module 200, configured to obtain local Z-axis height information of the front and back surfaces of the wafer by analyzing the reflection light signals;

[0101] a second control module 300, configured to control the upper and lower optical objectives to move axially according to the local Z-axis height information, so as to adjust the respective optical focal planes to the corresponding specified Z-axis height, so that the optical focal plane of each optical objective is accurately coincided with the vertical height position of the alignment mark to be observed on the front and back surfaces of the wafer;

[0102] an identification module 400, configured to obtain a region image containing the alignment marks on the front and back surfaces of the wafer after the optical focal plane adjustment is completed, and identify the geometric center coordinates of the alignment marks in the region image;

[0103] a calculation module 500, configured to calculate the alignment deviation between the front and back surfaces of the wafer according to the geometric center coordinates of the alignment marks;

[0104] a third control module 600, configured to control the worktable to move or rotate to compensate for the deviation according to the alignment deviation.

[0105] In some embodiments, the analysis module 200 performs the following when obtaining the local Z-axis height information of the front and back surfaces of the wafer by analyzing the reflection light signals:

[0106] S21. Obtain a preliminary Z-axis height range of the front and back surfaces of the wafer by analyzing the reflection light signals;

[0107] S22. Control the optical objective to scan along the Z-axis within the corresponding preliminary Z-axis height range, and collect a series of scanning images corresponding to the scanning process;

[0108] S23. Evaluate the sharpness of the scanning images, and take the Z-axis height position corresponding to the best sharpness of the scanning image as the corresponding local Z-axis height information, to obtain the calibrated local Z-axis height information of the front and back surfaces of the wafer.

[0109] In some embodiments, the analysis module 200 performs the following steps when used to obtain the preliminary Z-axis height range of the front and back surfaces of the wafer by analyzing the reflected light signal:

[0110] S211. Preprocess the reflected light signal to obtain a preprocessed reflected light signal;

[0111] S212. Obtain the preliminary Z-axis height range of the front and back surfaces of the wafer by analyzing the preprocessed reflected light signal.

[0112] In some embodiments, the calculation module 500 performs the following steps when used to calculate the alignment deviation between the front and back surfaces of the wafer according to the geometric center coordinates of the alignment marks:

[0113] S51. Perform point set matching on the geometric center coordinates of the alignment marks to obtain a corresponding point set;

[0114] S52. Based on the corresponding point set, calculate the translation transformation parameter and / or the rotation transformation parameter that minimizes the distance residual between the corresponding point sets;

[0115] S53. Calculate the alignment deviation between the front and back surfaces of the wafer according to the translation transformation parameter and / or the rotation transformation parameter.

[0116] In some embodiments, the calculation module 500 performs the following steps when used to calculate the translation transformation parameter and / or the rotation transformation parameter that minimizes the distance residual between the corresponding point sets based on the corresponding point set:

[0117] S521. Based on the corresponding point set, calculate the translation transformation parameter and / or the rotation transformation parameter by least squares method.

[0118] In some embodiments, the calculation module 500 performs the following steps when used to calculate the alignment deviation between the front and back surfaces of the wafer according to the translation transformation parameter and / or the rotation transformation parameter:

[0119] S531. Transform the geometric center coordinates of all alignment marks on the front surface of the wafer to the back surface coordinate system of the wafer by the translation transformation parameter and / or the rotation transformation parameter to obtain transformed front surface mark points of the wafer;

[0120] S532. Calculate the average distance or maximum distance between the transformed front surface mark points of the wafer and the corresponding mark points on the back surface of the wafer;

[0121] S533. Take the average distance or maximum distance as the alignment deviation between the front and back surfaces of the wafer.

[0122] Please refer to Figure 3 , Figure 3 A structure schematic diagram of an electronic device provided by the embodiment of the present application, the present application provides an electronic device 13, comprising: a processor 1301 and a memory 1302, the processor 1301 and the memory 1302 are interconnected and communicate with each other through a communication bus 1303 and / or other forms of connecting mechanism (not marked), the memory 1302 stores computer readable instructions executable by the processor 1301, when the electronic device runs, the processor 1301 executes the computer readable instructions, to execute the method in any optional implementation manner of the above-mentioned embodiment, to realize the following functions: control the double field optical system to emit the detection light beam to the upper optical channel and the lower optical channel respectively, and receive the reflection light signal of the respective reflected light; by analyzing the reflection light signal, the local Z axis height information of the two sides of the wafer is obtained; according to the local Z axis height information, the axial movement of the upper and lower optical objectives is controlled, so that the optical focal plane of each optical objective is adjusted to the corresponding specified Z axis height, so that the optical focal plane of each optical objective is accurately coincided with the vertical height position of the alignment mark to be observed on the two sides of the wafer; after the optical focal plane adjustment is completed, the area image containing the alignment mark of the two sides of the wafer is obtained, and the geometric center coordinates of the alignment mark in the area image are identified; according to the geometric center coordinates of the alignment mark, the alignment deviation between the two sides of the wafer is calculated; according to the alignment deviation, the workbench is controlled to move or rotate to compensate the deviation.

[0123] The embodiment of the present application provides a computer readable storage medium, which stores a computer program, when the computer program is executed by a processor, the method in any optional implementation manner of the above-mentioned embodiment is executed, to realize the following functions: control the double field optical system to emit the detection light beam to the upper optical channel and the lower optical channel respectively, and receive the reflection light signal of the respective reflected light; by analyzing the reflection light signal, the local Z axis height information of the two sides of the wafer is obtained; according to the local Z axis height information, the axial movement of the upper and lower optical objectives is controlled, so that the optical focal plane of each optical objective is adjusted to the corresponding specified Z axis height, so that the optical focal plane of each optical objective is accurately coincided with the vertical height position of the alignment mark to be observed on the two sides of the wafer; after the optical focal plane adjustment is completed, the area image containing the alignment mark of the two sides of the wafer is obtained, and the geometric center coordinates of the alignment mark in the area image are identified; according to the geometric center coordinates of the alignment mark, the alignment deviation between the two sides of the wafer is calculated; according to the alignment deviation, the workbench is controlled to move or rotate to compensate the deviation.

[0124] The computer readable storage medium can be realized by any type of volatile or nonvolatile storage devices or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk or optical disk.

[0125] In the embodiments of the present application, it should be understood that the disclosed device and method can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of the units is merely a logical function division. In actual implementation, another division manner can be used. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some communication interfaces, devices or units, and can be electrical, mechanical or other forms.

[0126] In addition, the units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0127] Furthermore, the functional modules in each of the embodiments of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0128] In this article, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations.

[0129] The above merely illustrates the embodiments of the present application but should not be taken as limitations to the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for positioning a double-sided exposed wafer, characterized in that, Includes the following steps: S1. Control the dual-field optical system to emit detection beams to the upper optical channel and the lower optical channel respectively, and receive the reflected light signals of their respective reflected light; S2. By analyzing the reflected light signal, the local Z-axis height information of the front and back sides of the wafer is obtained; S3. Based on the local Z-axis height information, control the axial movement of the upper and lower optical objectives to adjust their respective optical focal planes to the corresponding specified Z-axis height, so that the optical focal plane of each optical objective precisely coincides with the vertical height position of the alignment mark to be observed on both sides of the wafer; S4. After the optical focal plane is adjusted, acquire an image of the region containing the alignment marks on both sides of the wafer, and identify the geometric center coordinates of the alignment marks in the region image; S5. Calculate the alignment deviation between the front and back sides of the wafer based on the geometric center coordinates of the alignment mark; S6. Based on the alignment deviation, control the table to move or rotate to compensate for the deviation.

2. The double-sided exposure wafer positioning method according to claim 1, characterized in that, The specific steps in step S2 include: S21. By analyzing the reflected light signal, obtain the preliminary Z-axis height range of the front and back sides of the wafer; S22. Control the optical objective lens to scan along the Z-axis within the corresponding initial Z-axis height range, and acquire a series of corresponding scan images during the scanning process; S23. Evaluate the sharpness of the scanned image and take the Z-axis height position corresponding to the scanned image with the best sharpness as the corresponding local Z-axis height information to obtain the local Z-axis height information of the front and back sides of the calibrated wafer.

3. The double-sided exposure wafer positioning method according to claim 2, characterized in that, The specific steps in step S21 include: S211. Preprocess the reflected light signal to obtain the preprocessed reflected light signal; S212. By analyzing the preprocessed reflected light signal, the preliminary Z-axis height range of the front and back sides of the wafer is obtained.

4. The double-sided exposure wafer positioning method according to claim 3, characterized in that, Preprocessing includes removing transient outliers and performing local smoothing to suppress local fluctuations and spurious peaks caused by random contaminants or local roughness inhomogeneities.

5. The double-sided exposure wafer positioning method according to claim 1, characterized in that, The specific steps in step S5 include: S51. Perform point set matching on the geometric center coordinates of the alignment markers to obtain the corresponding point set; S52. Based on the corresponding point sets, calculate the translation transformation parameters and / or rotation transformation parameters that minimize the distance residual between the corresponding point sets; S53. Calculate the alignment deviation between the front and back sides of the wafer based on the translation transformation parameters and / or rotation transformation parameters.

6. The double-sided exposure wafer positioning method according to claim 5, characterized in that, The specific steps in step S52 include: S521. Based on the corresponding point set, calculate the translation transformation parameters and / or rotation transformation parameters using the least squares method.

7. The double-sided exposure wafer positioning method according to claim 5, characterized in that, The specific steps in step S53 include: S531. Transform the geometric center coordinates of all alignment marks on the front side of the wafer to the coordinate system on the back side of the wafer through translation and / or rotation transformation parameters to obtain the transformed wafer front side mark points; S532. Calculate the average or maximum distance between the transformed wafer front-side marker and the corresponding wafer back-side marker; S533. Use the average distance or maximum distance as the alignment deviation between the front and back sides of the wafer.

8. A double-sided exposure wafer positioning device, characterized in that, include: The first control module is used to control the dual-field optical system to emit detection beams to the upper optical channel and the lower optical channel respectively, and to receive the reflected light signals of their respective reflected light. The analysis module is used to obtain local Z-axis height information of the front and back sides of the wafer by analyzing the reflected light signal; The second control module is used to control the axial movement of the upper and lower optical objectives based on the local Z-axis height information, so as to adjust their respective optical focal planes to the corresponding specified Z-axis height, so that the optical focal plane of each optical objective is precisely aligned with the vertical height position of the alignment mark to be observed on both sides of the wafer. The recognition module is used to acquire an image of the region containing alignment marks on both sides of the wafer after the optical focal plane is adjusted, and to identify the geometric center coordinates of the alignment marks in the region image; The calculation module is used to calculate the alignment deviation between the front and back sides of the wafer based on the geometric center coordinates of the alignment mark; The third control module is used to control the movement or rotation of the worktable to compensate for the alignment deviation.

9. An electronic device, characterized in that, It includes a processor and a memory, the memory storing computer-readable instructions, which, when executed by the processor, perform the steps of the double-sided exposure wafer positioning method as described in any one of claims 1-7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it performs the steps in the double-sided exposure wafer positioning method as described in any one of claims 1-7.

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