Wafer bonding methods, apparatuses, devices, and storage media

Abstract

The application provides a wafer bonding method, device, equipment and storage medium, and belongs to the technical field of semiconductor manufacturing. The wafer bonding device comprises an upper camera, a lower camera, a first reference frame, a second reference frame and a controller. The opposite two sides of the end of the first reference frame and the opposite two sides of the end of the second reference frame are provided with target plates. The controller is used for controlling the upper camera to take an overhead shot of the target plates on the upper sides of the two reference frames and controlling the lower camera to take an overhead shot of the target plates on the lower sides of the two reference frames before bonding the wafer each time. The corresponding camera offset difference during the wafer bonding is calculated based on the corresponding shooting results of the upper camera and the lower camera. The position of the bonding head and the position of the workbench are adjusted based on the camera offset difference, and the wafer bonding is performed by the bonding head after the position of the bonding head and the position of the workbench are adjusted. The application can improve the alignment accuracy during wafer bonding.

Description

Technical Field

[0001] This application belongs to the field of semiconductor manufacturing technology, and more specifically, relates to a wafer bonding method, apparatus, device and storage medium. Background Technology

[0002] Hybrid bonding is a key process for achieving 3D integration and heterogeneous integration, requiring alignment of the bonding surfaces of the chip and the underlying wafer at the nanometer to submicrometer level. To this end, some hybrid bonding equipment is equipped with upper and lower cameras to capture the alignment marks on the upper and lower bonding surfaces, respectively. The relative positional deviation between the two is calculated through image processing, and then the bonding head fine-tuning mechanism and the stage motion table work together to perform alignment.

[0003] In related technologies, error compensation for vertical alignment typically relies on offline calibration using a single calibration board before operation, and on indirectly calculating temperature drift during operation based on fixed marker spacing or virtual markers, then correcting using discrete-level compensation files. However, this approach has the following common drawbacks: First, after the calibration board is removed during operation, the upper and lower cameras lack an online common geometric reference, resulting in a time lag between the offline compensation file and the dynamic operating conditions, making it difficult to reflect the real-time geometric state during operation. Second, discrete-level temperature compensation cannot cover the continuous dynamic temperature rise process from standby to full load, leading to a disconnect between the compensation value and the operating conditions when the process heat load changes drastically, resulting in a significant decrease in alignment accuracy.

[0004] Therefore, how to achieve high precision and high stability of top and bottom alignment in the hybrid bonding process is one of the key problems that urgently need to be solved in this field. Summary of the Invention

[0005] The purpose of this application is to provide a wafer bonding method, apparatus, device, and storage medium that matches the current working conditions when adjusting the position of the bonding head and the stage, thereby alleviating the problem of the disconnect between discrete settings and continuous dynamic temperature rise, and further stabilizing alignment accuracy.

[0006] A first aspect of this application provides a wafer bonding apparatus, including: an upper camera, a lower camera, a first reference frame, a second reference frame, and a controller; The first and second reference frames are arranged side by side in the field of view of the two cameras; target plates are evenly distributed on the two opposite ends of the first reference frame and the two opposite ends of the second reference frame. The controller is used to control the upper camera to take a top-down view of the target plates on the upper sides of the two reference frames and to control the lower camera to take a bottom-up view of the target plates on the lower sides of the two reference frames before each wafer bonding operation. For each reference frame, the controller determines the actual position of the target plate on the upper side of the reference frame based on the shooting results and calculates a first deviation between the actual position of the target plate and a standard position. It also determines the actual position of the target plate on the lower side of the reference frame based on the shooting results and calculates a second deviation between the actual position of the target plate and a standard position. Based on the first and second deviations, it determines the initial camera offset difference between the two cameras when shooting the reference frame. Finally, it determines the camera offset difference for the wafer bonding operation based on the initial camera offset difference between the two cameras when shooting each reference frame. The controller is also used to control the bonding head to perform wafer bonding after adjusting the position of the bonding head and the position of the worktable.

[0007] A second aspect of this application provides a method for determining camera offset difference during wafer bonding, including: The image captures the upper side of the first and second reference frames by the upper camera in the wafer bonding equipment, and the image captures the lower side of the first and second reference frames by the lower camera in the wafer bonding equipment; wherein, the two reference frames are arranged side by side in parallel in the field of view of the two cameras; target plates are evenly distributed on the two opposite ends of the first reference frame and the two opposite ends of the second reference frame. For each reference frame, the actual position of the target plate on the upper side of the reference frame is determined based on the shooting results, and the first deviation between the actual position of the target plate and the standard position is calculated; the actual position of the target plate on the lower side of the reference frame is determined based on the shooting results, and the second deviation between the actual position of the target plate and the standard position is calculated; the initial camera offset difference between the two cameras when shooting the reference frame is determined based on the first deviation and the second deviation. The camera offset difference during wafer bonding is determined based on the initial camera offset difference when the two cameras capture images of each reference frame.

[0008] Furthermore, the first reference frame is mounted on the outer frame of the wafer bonding equipment via a floating thermal insulation support, and the second reference frame is mounted on the worktable of the wafer bonding equipment; the upper camera and the lower camera change their shooting positions by moving on their respective guide rails; the shooting results include the shooting results of the upper camera and the shooting results of the lower camera.

[0009] Determining the actual position of the target plate on the upper side of the reference frame based on the shooting results includes: The first offset is determined based on the temperature of the upper camera and the temperature of the guide rail corresponding to the upper camera. Based on the position of the target plate in the shooting results of the upper camera and the first offset, the actual position of the target plate on the upper side of the reference frame is determined. Determining the actual position of the target plate on the lower side of the reference frame based on the shooting results includes: The second offset is determined based on the temperature of the lower camera, the temperature of the guide rail corresponding to the lower camera, and the temperature of the worktable. Based on the position of the target plate in the shooting results of the lower camera and the second offset, the actual position of the target plate on the lower side of the reference frame is determined.

[0010] Furthermore, determining the first offset based on the temperature of the upper camera and the temperature of the guide rail corresponding to the upper camera includes: Based on the temperature of the upper camera, determine the positional offset caused by the thermal expansion of the upper camera at the temperature, resulting in the translation of the camera's optical center, and determine the internal imaging offset of the upper camera at the temperature. The intrinsic parameter offset of the upper camera is determined based on the position offset and internal imaging offset of the upper camera. Calculate the first temperature difference between the temperature of the guide rail corresponding to the camera and the standard reference temperature; The offset of the upper camera relative to the guide rail is obtained based on the distance between each target plate captured by the upper camera and the preset thermal expansion reference point of the guide rail and the first temperature difference. The first offset is obtained by summing the intrinsic parameter offset of the upper camera and the corresponding guide rail offset of the upper camera.

[0011] Furthermore, the second offset is determined based on the temperature of the lower camera, the temperature of the guide rail corresponding to the lower camera, and the temperature of the worktable, including: Based on the temperature of the lower camera, determine the positional offset caused by the thermal expansion of the lower camera at a given temperature, resulting in the translation of the camera's optical center, and determine the internal imaging offset of the lower camera at a given temperature. The lower camera intrinsic parameter offset is determined based on the position offset and internal imaging offset of the lower camera. Calculate the second temperature difference between the temperature of the guide rail corresponding to the camera and the standard reference temperature; The offset of the guide rail corresponding to the lower camera is obtained based on the distance between each target plate captured by the lower camera and the preset thermal expansion reference point of the guide rail and the second temperature difference. Calculate the third temperature difference between the workbench temperature and the standard reference temperature; The table reference offset is obtained based on the distance between the thermal expansion reference center of the worktable and the preset alignment reference position and the third temperature difference. The second offset is obtained by summing the lower camera intrinsic parameter offset, the lower camera corresponding guide rail offset, and the worktable reference offset.

[0012] Furthermore, after calculating the initial camera offset difference, the camera offset difference determination method also includes: For each camera, based on the standard and actual positions of the two target plates in the camera's shooting results, determine the displacement of the target plate in each reference frame in the camera's shooting results. The average displacement between the two reference frames is determined based on the displacements of the upper and lower cameras, respectively.

[0013] The camera offset difference is determined based on the initial camera offset difference between the two cameras when capturing images of each reference frame, including: If the average displacement does not exceed the first displacement threshold, the initial camera offset difference is determined as the camera offset difference. If the average displacement exceeds the first displacement threshold, control each camera to re-capture the target plate of the first and second reference frames, and determine the updated initial camera offset difference and the updated average displacement based on the re-capture results. If the updated average displacement does not exceed the preset second displacement threshold, then the updated initial camera offset difference is determined as the camera offset difference.

[0014] Furthermore, adjusting the position of the bonding head and the position of the worktable based on the camera offset difference includes: The residual drift on the lower camera side is obtained by summing the camera offset difference and the residual drift on the upper camera side. Among them, the residual drift on the upper camera side is the first deviation; The actual position of the wafer is determined based on the wafer's position, first offset, and residual drift on the upper camera side in the image captured by the upper camera. The actual position of the chip is determined based on the chip's position, second offset, and residual drift on the lower camera side in the shooting results of the lower camera. The alignment deviation is determined based on the actual position of the chip and the actual position of the wafer; Adjust the position of the key head and the position of the worktable based on the alignment deviation.

[0015] Furthermore, a first offset is determined based on the temperature of the upper camera and the temperature of the guide rail corresponding to the upper camera; a second offset is determined based on the temperature of the lower camera, the temperature of the guide rail corresponding to the lower camera, and the temperature of the worktable. Determining the actual position of the target plate on the upper side of the reference frame based on the shooting results includes: determining the actual position of the target plate on the upper side of the reference frame based on the position of the target plate in the shooting results of the upper camera and the first offset. Determining the actual position of the target plate on the lower side of the reference frame based on the shooting results includes: determining the actual position of the target plate on the lower side of the reference frame based on the position of the target plate in the shooting results of the lower camera and the second offset.

[0016] A third aspect of the embodiments of this application provides a wafer bonding alignment apparatus, including: an upper camera, a lower camera, a first reference frame, and a second reference frame; The first and second reference frames are arranged side by side in the field of view of the two cameras; target plates are evenly distributed on the two opposite ends of the first reference frame and the two opposite ends of the second reference frame. The two target plates at the ends of the first reference frame and the two target plates at the ends of the second reference frame are connected by a material with a thermal expansion coefficient lower than the expansion coefficient threshold, so that the relative position of the two target plates of the same reference frame remains constant. The upper and lower cameras are used to photograph the target plate to obtain the photographic results, so that the camera offset difference corresponding to wafer bonding can be calculated and determined based on the photographic results before wafer bonding. The first reference frame is mounted on the outer frame of the wafer bonding equipment via a floating heat-insulating support, and the second reference frame is mounted on the worktable of the wafer bonding equipment; the upper camera and the lower camera change their shooting positions by moving on their respective guide rails.

[0017] A fourth aspect of this application provides a wafer bonding method, comprising: The camera offset difference is obtained using a camera offset difference determination method. The upper camera is controlled to move on the corresponding guide rail to take pictures of the wafer to be bonded, and the lower camera is controlled to move on the corresponding guide rail to take pictures of the chip to be bonded. The position of the bonding head and the position of the worktable are adjusted based on the camera offset difference, and the bonding head is controlled to perform wafer bonding.

[0018] A fifth aspect of this application provides a wafer bonding control device, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of the camera offset difference determination method described above, or the steps of the wafer bonding method.

[0019] A sixth aspect of the embodiments of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the camera offset difference determination method or the steps of the wafer bonding method described above.

[0020] The beneficial effects of the wafer bonding method, apparatus, device, and storage medium provided in this application are as follows: In this embodiment, the first and second reference frames are fixed components of the bonding device, arranged side-by-side in parallel in the area where the fields of view of the upper and lower cameras intersect, and do not need to be removed after offline calibration before operation. The controller takes real-time pictures of the target plates of the two frames before each bonding, so that the upper and lower cameras always have an online common geometric reference during the operation, eliminating the time difference between offline compensation files and dynamic working conditions, and can reflect the real-time geometric state at the time of bonding, ensuring the timeliness and accuracy of the alignment reference.

[0021] In this embodiment, for each reference frame, the target plate on its upper side is photographed from above by the upper camera, and the target plate on its lower side is photographed from below by the lower camera. The actual positions of the two are compared with the standard positions to obtain the first deviation and the second deviation. Since the upper and lower target plates of the same reference frame correspond to the same physical reference, when determining the initial camera offset difference based on the first and second deviations, the position components of the reference frame itself cancel each other out, so that the initial camera offset difference mainly reflects the offset of the two cameras themselves. Then, the camera offset difference for this wafer bonding is determined by the initial camera offset difference of each of the two reference frames. The two reference frames serve as redundant checks for each other, further improving the accuracy of the camera offset difference determination. The camera offset difference is determined in real time for each bonding, so that the adjustment of the position of the bonding head and the worktable matches the current working conditions, alleviating the problem of the disconnect between discrete gears and continuous dynamic temperature rise, and further stabilizing the alignment accuracy. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a structural diagram of a wafer bonding apparatus provided in one embodiment of this application; Figure 2 This is a partial enlarged view of a wafer bonding apparatus provided in an embodiment of this application; Figure 3 A structural diagram of a first reference block and a second reference block provided in an embodiment of this application; Figure 4 A schematic diagram of the shooting results provided by the upper and lower cameras according to an embodiment of this application; Figure 5 A schematic diagram of the working principle of a wafer bonding device provided in an embodiment of this application; Figure 6 A schematic flowchart illustrating a camera offset difference determination method provided in an embodiment of this application; Figure 7 A schematic flowchart illustrating a camera offset difference determination method provided in another embodiment of this application; Figure 8 A schematic flowchart of a wafer bonding method provided in an embodiment of this application; Figure 9 A schematic flowchart of a wafer bonding method provided in another embodiment of this application; Figure 10 This is a schematic block diagram of a wafer bonding control device provided in one embodiment of this application; Figure label: 1. Upper camera; 2. Lower camera; 3. First reference frame; 4. Second reference frame; 5. Upper camera guide rail; 6. Lower camera guide rail; 7. Outer frame; 8. Worktable; 9. Clamping fixture; 10. Clamping fixture guide rail; 11. Bonding head; 12. Wafer; 31. Upper target plate of the first reference frame; 32. Lower target plate of the first reference frame; 33. Spacer frame of the first reference frame; 41. Upper target plate of the second reference frame; 42. Lower target plate of the second reference frame; 43. Spacer frame of the second reference frame; 1000. Wafer bonding control device; 1001. Processor; 1002. Input device; 1003. Output device; 1004. Memory; 1005. Communication bus. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solutions in the embodiments of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in the specific implementation of this application should fall within the protection scope of the embodiments of this application.

[0025] To keep the drawings concise, each drawing only schematically shows the parts relevant to the disclosure; these do not represent the actual structure of the product. Furthermore, for ease of understanding, in some drawings, only one of components with the same structure or function is schematically shown, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one," and "several" includes "two" and "more than two."

[0026] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0027] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0028] It should be understood that, unless the context clearly states otherwise, the terms "comprising," "including," or "having" as used herein refer to the presence of an element, but do not exclude the presence or addition of one or more other elements. Furthermore, "comprising" and / or "including" as used herein specify the presence of shapes, numbers, steps, operations, members, elements, and / or combinations thereof, and do not exclude the presence or addition of one or more other shapes, numbers, operations, elements, and / or combinations thereof. Some embodiments of this application are described in detail below with reference to the accompanying drawings. Where there is no conflict between the embodiments, the following embodiments and features can be combined with each other. The steps in the following method embodiments are for illustrative purposes only and are not intended to limit this application.

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the following description will be provided in conjunction with the accompanying drawings and specific embodiments.

[0030] This embodiment provides a wafer bonding device, referenced... Figure 1 and Figure 2 The wafer bonding equipment includes an upper camera 1, a lower camera 2, a first reference frame 3, a second reference frame 4, and a controller. Figure 1 and Figure 2 (Not shown in the image).

[0031] The first reference frame 3 and the second reference frame 4 are arranged side by side in the intersection area of ​​the fields of view of the two cameras. This intersection area refers to the intersection within the horizontal projection of the set of positions that can be captured by the upper side of the two reference frames within the movement range of the upper camera 1 and the set of positions that can be captured by the lower side of the two reference frames within the movement range of the lower camera 2. The movement range of the upper camera 1 refers to the movement range of the upper camera 1 along its corresponding guide rail (which can be the upper camera guide rail 5); the movement range of the lower camera 2 refers to the movement range of the lower camera 2 along its corresponding guide rail (which can be the lower camera guide rail 6).

[0032] Target plates are evenly distributed on the two opposite ends of the first reference frame 3 and the two opposite ends of the second reference frame 4. The first reference frame 3 is connected to the outer frame 7 of the wafer bonding equipment, and the second reference frame 4 is connected to the table surface of the worktable 8 of the wafer bonding equipment. Specifically, the first reference frame 3 is connected to the worktable 8 of the wafer bonding equipment via a floating heat-insulating support ( Figure 1 The first reference frame 3 (not shown) is mounted on the outer frame of the equipment and extends to the upper side of the wafer bonding area; the second reference frame 4 is mounted on the table surface of the worktable 8 (i.e., the marble table surface of the bonding machine) and is located within the bonding working area. Since the first reference frame 3 is supported by the outer frame 7 and the second reference frame 4 is fixed to the table surface of the worktable 8, the mounting bases of the two reference frames are respectively located in the thermal environment above and below the wafer bonding area, and their respective temperature change paths are independent of each other.

[0033] The upper camera 1 and the lower camera 2 change their shooting positions by moving along their respective guide rails. In this embodiment, the upper camera 1 moves along the X-guide rail and the lower camera 2 moves along the Y-guide rail. Both cameras can move along their guide rails to the aforementioned field of view intersection area and image the two reference frames respectively within this area.

[0034] The center-to-center distance between the first reference frame 3 and the second reference frame 4 is no greater than the width of the intersection area of ​​the two camera fields of view in the side-by-side direction, and no less than the minimum effective shooting distance for a single camera to image a single reference frame. Further, the center-to-center distance between the first reference frame 3 and the second reference frame 4 can be 20mm to 30mm. In this embodiment, the side-by-side direction, relative position, and center-to-center distance of the two reference frames can also be determined based on the field of view sizes of the upper camera 1 and the lower camera 2 to ensure that the cameras can capture images of the target plates on the two reference frames.

[0035] Furthermore, in order to keep the relative positions of the two target plates within the same reference frame constant, the reference... Figure 3 The two target plates at the ends of the first reference frame 3 (the upper target plate 31 and the lower target plate 32 of the first reference frame) and the two target plates at the ends of the second reference frame 4 (the upper target plate 41 and the lower target plate 42 of the second reference frame) are connected by materials with a thermal expansion coefficient lower than the expansion coefficient threshold. In addition, the number of target plates on each face of each reference frame can be one or more. This embodiment uses one target plate per face of each reference frame as an example. If there are multiple target plates on each face of each reference frame, the fitting center or fitting coordinate system of the multiple target plates can be used as the observation coordinates of that face, and calculations can be performed based on these observation coordinates. This embodiment does not limit the number of target plates on each face of each reference frame.

[0036] In this embodiment, the material is a low-expansion material spacer frame sandwiched between two target plates. Specifically, it can be Invar 4J36, microcrystalline glass, Zerodur type, etc., with a coefficient of thermal expansion on the order of <2×10⁻⁶. -6 / K. The stress-relieving connection structure between the spacer frame and the target plate can be a flexible hinge or a low thermal conductivity pad.

[0037] The upper target plate 31 and the lower target plate 32 of the first reference frame are separated by a spacer frame 33, and the upper target plate 41 and the lower target plate 42 of the second reference frame are separated by a spacer frame 43. The relative positional relationship between the two target plates in their respective target plate coordinate systems is a preset fixed value; in this embodiment, the fixing connector between the two target plates is made of low expansion steel.

[0038] Because the coefficient of thermal expansion of the connector between the two target plates of the same reference frame is lower than the expansion coefficient threshold, the change in the relative position between the two target plates of the same reference frame when the temperature changes is constrained to a range determined by both the coefficient of thermal expansion and the distance between the two target plates. This ensures that the relative positional relationship between the two target plates of the same reference frame remains a preset fixed value even under different thermal environments on the upper and lower sides. This preset fixed value enables differential calculations between the following four imaging results and provides a geometric constant that does not change with operating conditions for the differential calculations.

[0039] Temperature sensors are also installed on the upper camera 1, lower camera 2, upper camera guide rail 5, lower camera guide rail 6, and worktable 8. Figure 1 and Figure 2 (Not shown in the image) This sensor is used to collect temperature data at different locations. Specifically, it comprises a first temperature sensor mounted on the housing of the upper camera 1, a second temperature sensor mounted on the housing of the lower camera 2, a third temperature sensor mounted on the upper camera guide rail 5, a fourth temperature sensor mounted on the lower camera guide rail 6, and a fifth temperature sensor mounted on the worktable 8. The controller is communicatively connected to the aforementioned temperature sensors and is configured to calculate the camera offset difference based on the temperature data from the sensors, the position of the target plate in the image captured by the upper camera 1, and the position of the target plate in the image captured by the lower camera 2. Based on the camera offset difference, the controller adjusts the position of the bonding head and the position of the worktable to meet the precision requirements of wafer bonding.

[0040] Furthermore, before each wafer bonding operation, the controller controls the upper camera 1 to take a top-down view of the target plates on the upper sides of the first reference frame 3 and the second reference frame 4, and controls the lower camera 2 to take a bottom-up view of the target plates on the lower sides of the first reference frame 3 and the second reference frame 4. Thus, four sets of cross-image results are obtained in a single observation: Reference Figure 4The coordinates of the first target plate A obtained by the upper camera 1 from the upper side of the first reference frame 3, the coordinates of the second target plate B obtained by the lower camera 2 from the lower side of the first reference frame 3, the coordinates of the third target plate C obtained by the upper camera 1 from the upper side of the second reference frame 4, and the coordinates of the fourth target plate D obtained by the lower camera 2 from the lower side of the second reference frame 4 are as follows: The coordinates of A and C are given by the upper camera 1 in the same coordinate system, and the coordinates of B and D are given by the lower camera 2 in the same coordinate system.

[0041] Since both the first reference frame 3 and the second reference frame 4 are fixed components of the wafer bonding equipment and are always within the intersection area of ​​the moving field of view of the upper camera 1 and the lower camera 2, the observation process in this embodiment does not require moving the offline calibration tool in or out. The upper camera 1 and the lower camera 2 have geometric references before each wafer bonding operation. Compared with the existing technology that uses a single quartz glass calibration plate for offline observation, the online observation method in this embodiment can perform calibration before each wafer bonding operation and adjust or maintain the position of the bonding head and the worktable, thereby eliminating the compensation time difference between offline calibration and bonding operation conditions, and thus improving the accuracy of wafer bonding.

[0042] Furthermore, after one observation is completed, the controller can also control the upper camera 1 and the lower camera 2 to move on their respective guide rails to take multiple pictures. The camera offset difference can be calculated based on the results of the multiple pictures.

[0043] Furthermore, the upper camera 1 and the lower camera 2 can be triggered sequentially to avoid crosstalk between the illumination optical paths at the intersection of the fields of view when the two cameras are exposed simultaneously. The interval between the two triggers is controlled in milliseconds (e.g., 1~2ms), which is much smaller than the thermal drift characteristic time of the device structure (seconds or more). The amount of drift evolution within the interval is much smaller than the observation noise and can be ignored. Sequential triggering is equivalent to synchronous observation and does not affect the effectiveness of differential decoupling. The triggering order of the two cameras is not limited, and the same exposure parameters are used. The specific selection and setting of exposure parameters are not limited in this embodiment.

[0044] In one implementation, the controller specifically determines the camera offset difference corresponding to wafer bonding through the following steps: For each reference frame, the actual position of the target plate on the upper side of the reference frame is determined based on the shooting results, and the first deviation between the actual position of the target plate and the standard position is calculated. Based on the shooting results, determine the actual position of the target plate on the lower side of the reference frame, and calculate the second deviation between the actual position of the target plate and the standard position; The initial camera offset difference between the two cameras when shooting the reference frame is determined based on the first and second deviations; the camera offset difference during wafer bonding is determined based on the initial camera offset difference when the two cameras shoot each reference frame.

[0045] In this embodiment, the shooting results include the shooting results of the upper camera 1 and the shooting results of the lower camera 2. The shooting results of the upper camera 1 include the images captured by the upper camera 1 as it moves along the upper camera guide rail 5 to each reference frame, and the shooting results of the lower camera 2 include the images captured by the lower camera 2 as it moves along the lower camera guide rail 6 to each reference frame. Based on the images captured above, the position information of the target plate on each reference frame during the shooting process of the upper camera 1 or the lower camera 2 can be determined. The standard position in this embodiment is the position measured according to the same shooting procedure at the cold calibration reference temperature. For each reference frame, based on the position information obtained during the shooting process and the offset corresponding to each camera below, the actual position of the target plate on the upper side of the reference frame and the actual position of the target plate on the lower side of the reference frame are determined.

[0046] Furthermore, the controller is specifically used to determine the actual position of the target plate on the upper side of the reference frame based on the following methods and shooting results: The first offset is determined based on the temperature of the upper camera 1 and the temperature of the guide rail corresponding to the upper camera 1. Based on the position of the target plate and the first offset in the shooting results of the upper camera 1, the actual position of the target plate on the upper side of the reference frame is determined. The controller is specifically used to determine the actual position of the target plate on the lower side of the reference frame based on the following methods and shooting results: The second offset is determined based on the temperature of the lower camera 2, the temperature of the guide rail corresponding to the lower camera 2, and the temperature of the worktable. Based on the position of the target plate in the shooting results of the lower camera 2 and the second offset, the actual position of the target plate on the lower side of the reference frame is determined.

[0047] In this embodiment, the temperature of the upper camera 1 The temperature of the lower camera 2 can be obtained through the first temperature sensor. The temperature of the guide rail corresponding to camera 1 can be acquired by the second temperature sensor. The temperature of the guide rail corresponding to the lower camera 2 can be obtained through a third temperature sensor. The temperature of the workbench can be acquired through a fourth temperature sensor. This information can be acquired using a fifth temperature sensor. Furthermore, the first offset can be determined as follows: Based on the temperature of the upper camera 1, determine the positional offset caused by the thermal expansion of the upper camera 1 at the temperature, resulting in the translation of the camera optical center, and determine the internal imaging offset of the upper camera 1 at the temperature. The intrinsic parameter offset of the upper camera 1 is determined based on the position offset and internal imaging offset corresponding to the upper camera 1; Calculate the first temperature difference between the temperature of the guide rail corresponding to camera 1 and the standard reference temperature; The offset of the guide rail corresponding to the upper camera 1 is obtained based on the distance between each target plate captured by the upper camera 1 and the preset thermal expansion reference point of the guide rail and the first temperature difference. The first offset is obtained by summing the intrinsic parameter offset of the upper camera 1 and the corresponding guide rail offset of the upper camera 1.

[0048] Furthermore, the second offset can be determined as follows: Based on the temperature of the lower camera 2, determine the positional offset caused by the thermal expansion of the lower camera 2 at the temperature, resulting in the translation of the camera optical center, and determine the internal imaging offset of the lower camera 2 at the temperature. The intrinsic parameter offset of the lower camera 2 is determined based on the position offset and internal imaging offset of the lower camera 2. Calculate the second temperature difference between the temperature of the guide rail corresponding to camera 2 and the standard reference temperature; The offset of the guide rail corresponding to the lower camera 2 is obtained based on the distance between each target plate captured by the lower camera 2 and the preset thermal expansion reference point of the guide rail and the second temperature difference. Calculate the third temperature difference between the temperature of workbench 8 and the standard reference temperature; The table reference offset is obtained based on the distance between the thermal expansion reference center of the worktable 8 and the preset alignment reference position and the third temperature difference. The second offset is obtained by summing the intrinsic parameter offset of the lower camera 2, the guide rail offset corresponding to the lower camera 2, and the reference offset of the worktable.

[0049] In this embodiment, the intrinsic parameter offsets of the upper camera 1 and the lower camera 2 are calculated based on the following formula: Camera intrinsic parameter offset: Δ1 = ΔP1(T1) + ΔK1(T1); Downward camera intrinsic parameter offset: Δ2=ΔP2(T2)+ΔK2(T2).

[0050] In the formula, Δ1 is the intrinsic parameter offset of the upper camera, Δ2 is the intrinsic parameter offset of the lower camera, and ΔP1(T1) is the temperature of the outer shell of the upper camera 1 at the specified temperature. The positional shift caused by the translation of the camera's optical center due to thermal expansion, ΔK1(T1) is the positional shift of the upper camera 1 at temperature... The internal imaging offset at the location, ΔP2(T2), is the temperature of the lower camera 2 housing at the location. The positional shift caused by the translation of the camera's optical center due to thermal expansion, ΔK2(T2) is the positional shift of camera 2 at temperature [temperature value missing]. The internal imaging offset at that location.

[0051] As the motor drives the upper camera 1 and the lower camera 2 to move on their respective guide rails, the guide rails will generate heat due to friction, and thus expand and lengthen due to thermal expansion. Therefore, the actual physical position of the camera will change due to the thermal expansion of the guide rail. At this time, it is necessary to calculate the offset of the upper camera 1 along the X-axis and the offset of the lower camera 2 along the Y-axis.

[0052] In addition, the reference position of the stage 8 of the wafer bonding equipment will shift due to the increase in temperature caused by vacuum adsorption or heat generated by pneumatic components. At this time, it is necessary to calculate the reference offset of the stage.

[0053] The offset of the guide rail corresponding to camera 1: Δ3x A =α3x·(T3x T0)·x A ;Δ3x C =α3x·(T3x T0)·x C ; Offset of the guide rail corresponding to camera 2: Δ3y B =α3y·(T3y T0)·y B ;Δ3y D =α3y·(T3y T0)·y D ; Table reference offset: Δ4 = α4·(T4) T0)·L4; In the formula, x A x C These represent the effective distances along the X-axis from the first target plate A and the third target plate C to the preset thermal expansion reference point (fixed end) of the guide rail, i.e., the arm length of the guide rail thermal expansion. T0 is the cold-state calibration reference temperature, i.e., the standard reference temperature, and all thermal expansion calculations use this temperature as the zero point. B y D α3x and α3y are the effective distances from the second target plate B and the fourth target plate D along the Y direction to the preset guide rail thermal expansion reference point (fixed end), respectively, which are the arm lengths of the guide rail thermal expansion; α3x and α3y are the thermal expansion coefficients of the guide rail materials where the upper camera 1 and the lower camera 2 are located, respectively, and α4 is the thermal expansion coefficient of the worktable material.

[0054] After obtaining the above-mentioned intrinsic parameter offsets of the upper camera, the intrinsic parameter offset of the lower camera, the guide rail offset corresponding to upper camera 1, the guide rail offset corresponding to lower camera 2, and the reference offset of the worktable, based on the calculation method of the first and second offsets mentioned above, we can obtain: The first offset can be the sum of the intrinsic parameter offset of the upper camera 1 and the corresponding guide rail offset, that is: the first offset corresponding to the first target plate A is Δ1 + Δ3x A The first offset corresponding to the third target plate C is Δ1 + Δ3x C .

[0055] The second offset can be the sum of the lower camera 2 intrinsic parameter offset, the corresponding guide rail offset, and the worktable reference offset, that is: The second offset corresponding to the second target plate B is Δ2 + Δ3y B +Δ4, the second offset corresponding to the fourth target plate D is Δ2+Δ3y D +Δ4.

[0056] In this embodiment, the first offset and the second offset can be periodically updated based on the sampling period of each temperature sensor. Specifically, the first temperature sensor, the second temperature sensor, the guide rail temperature sensor, and the worktable temperature sensor sample the temperature of the upper camera 1, the temperature of the lower camera 2, the temperatures of the guide rails corresponding to the upper camera 1 and the lower camera 2, and the temperature of the worktable 8 according to their respective sampling periods. Each time a new temperature sampling value is acquired, the controller recalculates the intrinsic parameter offset of the upper camera, the intrinsic parameter offset of the lower camera, the offsets of each guide rail, and the reference offset of the worktable based on the latest temperature sampling value, and updates the first offset and the second offset. Thus, before each shot of the first and second reference frames, the first offset and the second offset used by the controller are both quantities determined based on the latest temperature sampling value; even if the temperature of the device changes between two observations, the first offset and the second offset will be updated accordingly, so that the offset corresponds to the thermal state at the time of the shot, avoiding the error introduced by correcting with a fixed offset.

[0057] Furthermore, the offset of each guide rail is related to the arm length from the shooting point along the guide rail direction to the guide rail thermal expansion reference point. When the controller takes a picture of the workpiece by moving the camera position on the guide rail, the guide rail offset corresponding to the shooting position can be obtained by linear interpolation based on the arm length along the guide rail direction of the shooting position and the guide rail offset at at least two determined shooting points.

[0058] Furthermore, the controller determines the actual position of the target board in the shooting results of the upper camera 1 based on the position of the target board in the shooting results of the upper camera 1 and the first offset; and determines the actual position of the target board in the shooting results of the lower camera 2 based on the position of the target board in the shooting results of the lower camera 2 and the second offset.

[0059] In this embodiment, the corrected actual positions of each target plate are as follows: A′=A Δ1 Δ3x A ; C′=C Δ1 Δ3x C ; B′=B Δ2 Δ3y B Δ4; D′=D Δ2 Δ3y D Δ4.

[0060] Wherein, A′ and C′ are the corrected actual positions of the first target plate A and the third target plate C in the shooting results of the upper camera 1, respectively; B′ and D′ are the corrected actual positions of the second target plate B and the fourth target plate D in the shooting results of the lower camera 2, respectively; A, B, C, and D are the positions of each target plate in the current shooting results; A0, B0, C0, and D0 are the cold calibration values ​​of each target plate measured under the same shooting procedure in the T0 thermal equilibrium state, that is, the standard positions corresponding to each target plate.

[0061] In this embodiment, after determining the actual position of each target plate, the deviation between the standard position and the actual position of each target plate can be calculated, thereby determining the initial camera offset difference when the two cameras capture images of each reference frame. The process of calculating the initial camera offset difference in this embodiment can also be called the differential decoupling process, and the specific process is as follows: Subtracting the corrected actual positions of the two target plates obtained from the same reference frame captured by the two cameras cancels out the common components of the reference frame positions, thus separating the residual drift difference between the two cameras after the first-order correction: ΔC1=(B′ A′) (B0) A0); ΔC2=(D′ C′) (D0) C0).

[0062] In this embodiment, the first deviation corresponding to the first target plate A is A′-A0, and the second deviation corresponding to the second target plate B is B′. B0, the first deviation corresponding to the third target plate C is C′-C0, and the second deviation corresponding to the fourth target plate D is D′-D0. The difference between the first and second deviations corresponding to the first reference frame is ΔC1, and the difference between the first and second deviations corresponding to the second reference frame is ΔC2. The initial camera offset difference is the average of ΔC1 and ΔC2, i.e., ΔC = (ΔC1 + ΔC2) / 2. Since ΔC1 and ΔC2 are two independent measurements of the same physical quantity (measured independently at two positions in the first and second reference frames respectively), averaging them halves the estimated variance.

[0063] The initial camera offset difference can also be the weighted average of ΔC1 and ΔC2, with each weighting coefficient negatively correlated with the ratio of the time constants of the two reference frames. Furthermore, considering the thermal response hysteresis of reference frames with larger time constants under dynamic temperature rise conditions, each weighting coefficient can be adaptively adjusted according to the temperature change rate. For example, the controller acquires the temperature change rate |dT / dt| of the temperature sensor per unit time, and the time constant τ of a certain reference frame... i The larger the product with |dT / dt|, the more significant the thermal response hysteresis of the reference frame under the current operating condition, and the smaller the corresponding weight coefficient. Under the quasi-steady-state condition where |dT / dt| approaches zero, the weight coefficients tend to be equal, and the system degenerates back to the averaging method.

[0064] In a parallel implementation, the deviation relationship between the two reference frames can also be constructed as an observation equation, and the initial camera offset difference can be solved by least squares fusion. When the observation equation only has the initial camera offset difference as an unknown, the least squares solution is equivalent to a weighted average weighted by the observation accuracy of each path.

[0065] In another parallel implementation, outlier checks can be performed on each observation before fusion. For example, M-estimation can be used to reduce the weight of observations with large deviations in the fusion process; or, based on the ΔC1 and ΔC2 sequences formed by previous observations before bonding, RANSAC can be used to remove outlier observations that deviate beyond a preset threshold (the threshold can be a multiple of σ, where σ is the standard deviation of a single observation measured in a cold-state repeatability experiment), and only the retained observations can be used to determine the initial camera offset difference. The removed observations often correspond to transient interference or slippage and loosening of the reference frame components, and the aforementioned retesting and alarm process can be triggered after removal.

[0066] Furthermore, the actual corrected positions of the two target plates obtained from two different reference frames captured by the same camera can be subtracted to cancel out the residual drift of the camera itself after the first-order correction, thus separating the relative micro-momentum between the two reference frames: δ Bdu =(C′ A′) (C0) A0); δ Bdd =(D′ B′) (D0) B0).

[0067] In the formula, A0, B0, C0 and D0 are the cold calibration values ​​corresponding to each target plate, that is, the standard positions corresponding to each target plate.

[0068] Furthermore, for each camera, the controller determines the displacement of the target plate in the camera's shooting results based on the standard and actual positions of the two target plates respectively in the camera's shooting results; and determines the average displacement of the target plate based on the displacement of the target plate in the shooting results of each camera.

[0069] In this embodiment, the displacement corresponding to the upper camera 1 is δ. Bdu The displacement corresponding to camera 2 is δ Bdd The average displacement of the target plate can be the average of the two, i.e., δ Bd =(δ Bdu +δ Bdd ) / 2. The average displacement is used to represent the relative micro-motion between two reference frames. It is not involved in the compensation calculation of camera offset difference, but serves as the input for reference state determination.

[0070] If the average displacement does not exceed the first displacement threshold, the controller determines the initial camera offset difference as the camera offset difference corresponding to this bonding. If the average displacement exceeds the first displacement threshold, the controller controls each camera to re-capture the target plate of the first reference frame 3 and the second reference frame 4, and determines the updated initial camera offset difference and the updated average displacement based on the re-capture results; if the updated average displacement does not exceed the preset second displacement threshold, the updated initial camera offset difference is determined as the camera offset difference.

[0071] In this embodiment, the baseline state is determined based on the following method: δ Bd正常 =α b ·(T b T0)·L b ; |δBd δ Bd正常 |≤τ m If the baseline state is deemed reliable, subsequent steps can be executed. |δ Bd δ Bd正常 |>τ m At this point, the current process is locked, and each camera is controlled to re-capture and analyze the target plates of the first reference frame 3 and the second reference frame 4.

[0072] If two reference frames are fixed to the same rigid reference member, the baseline between the two reference frames is zero, and the above criterion is simplified accordingly to |δ Bd |>τ m .

[0073] Among them, L b The distance between the two reference frames can be a structural design value; α b The coefficient of thermal expansion of the baseline structure between the two reference frames is T, which can be a material engineering value; b The temperature is the baseline structure temperature. When no independent measurement point is set, it can be replaced by the ambient temperature of T4 or the wafer bonding equipment.

[0074] In this embodiment, the first displacement threshold and the second displacement threshold can be the same value or different values. In a feasible implementation, the first displacement threshold is set to τ. m The second displacement threshold is τ. m′ In another feasible implementation, both the first displacement threshold and the second displacement threshold are taken as τ. m .

[0075] τ m The specific value is the larger of the relative displacement allowed by the structural design and 3σ, i.e., τ. m =max(strumentally permissible relative displacement, 3σ), where σ is the standard deviation of a single observation obtained from cold-state repeatability testing. The structurally permissible relative displacement is the maximum relative displacement allowed between two reference frames under thermal deformation, assembly stress, or external disturbances, provided the product process is qualified and the bonding yield meets requirements. In this embodiment, τ m σ is updated online via cold-state repeatability experiments (rolling window 3σ), δ Bd正常 T in the model b The temperature field fitted at multiple measurement points on the baseline structure is used to replace the temperature at a single point.

[0076] In this embodiment, the first displacement threshold is selected according to the above-mentioned standard. On the one hand, it can avoid false alarms caused by the random noise of the measuring equipment itself. On the other hand, it can also maintain the process safety boundary, so that the first displacement threshold does not exceed the maximum relative displacement allowed by the structural design. Once the reference frame experiences real stress slippage or abnormal deformation that exceeds the process tolerance that the equipment can withstand, the equipment can accurately identify the abnormality and intercept the current bonding process to avoid the generation of defective products.

[0077] In one implementation, after the controller controls each camera to re-measure the target plates of the first reference frame 3 and the second reference frame 4, if the updated average displacement does not exceed the preset second displacement threshold, it is determined to be an observation anomaly, that is, caused by transient disturbance, and the subsequent steps are continued with the re-measurement data; if the updated average displacement exceeds the preset second displacement threshold, it is determined to be a slippage or loosening of the reference frame component, and it is determined to be caused by a mechanical abnormality of the equipment. The process is then locked and an alarm is issued for maintenance. After the maintenance is confirmed, the camera offset difference calibration step is repeated.

[0078] In one feasible implementation, the number of retests, alarm type, and lockout release conditions can all be determined according to specific wafer bonding process requirements; this embodiment does not impose further limitations.

[0079] Furthermore, the controller also controls the upper camera 1 to move on its corresponding guide rail to capture images of the wafer 12 to be bonded, and controls the lower camera 2 to move on its corresponding guide rail to capture images of the chip to be bonded. In this embodiment, the controller determines the actual position of the wafer 12 based on the position of the wafer 12, the first offset, and the residual drift on the upper camera side in the image captured by the upper camera 1; determines the actual position of the chip based on the position of the chip, the second offset, and the residual drift on the lower camera side in the image captured by the lower camera 2; and determines the alignment deviation based on the actual position of the chip and the actual position of the wafer 12.

[0080] The specific calculation process is as follows: P 1clean =P1 Δ1 Δ3x P1 ; P 2clean =P2 Δ2 Δ3y P2 Δ4; P 1real =P 1clean ΔP head ΔP head =δ1 δ1 =A′ A0; P 2real =P 2clean ΔP chuck ΔP chuck =δ2 δ2 =δ1 +ΔC; ΔP=P 1real P 2real .

[0081] In the formula, P1 is the original coordinate of the wafer 12 to be bonded, captured by the upper camera 1, and P2 is the original coordinate of the chip to be bonded, captured by the lower camera 2; Δ3x P1 Δ3y P2 These represent the X-axis guide rail offset of the upper camera 1 at the wafer location and the Y-axis guide rail offset of the lower camera 2 at the chip location, respectively; in this embodiment, Δ3x P1 Δ3y P2 The calculation method is the same as the guide rail offset corresponding to upper camera 1 and lower camera 2 mentioned above. The only difference from the above is the shooting position. P 1clean P 2clean These represent the positions of wafer 12 in the image captured by upper camera 1 after offset removal, and the chip positions in the image captured by lower camera 2, respectively; ΔP head =δ1 δ1 The residual drift on the upper camera side, ΔP chuck =δ2 δ2 P represents the residual drift on the lower camera side. 1real For the actual location of wafer 12, P 2real ΔP represents the actual position of the chip, and ΔP represents the alignment deviation.

[0082] In this embodiment, since the wafer 12 is supported on the worktable and moves synchronously with the thermal expansion of the worktable, its position in the worktable coordinate system does not change due to the expansion of the worktable; while the chip is picked up and held by the bonding head 11 and does not move with the worktable 8. The expansion of the worktable 8 will change the position of the chip relative to the worktable coordinate system, so it is necessary to correct the worktable reference offset. Specifically, the worktable reference offset Δ4 is ​​used in the chip imaging result on the side of the lower camera 2 (P 2clean ), but not involved in the wafer imaging results on the side of camera 1 (P) 1clean ).

[0083] In one feasible implementation, the residual drift δ1 on the upper camera side The residual drift δ2 on the lower camera side is obtained using the first reference frame 3 as the anchor point. The above camera-side residual drift δ1 It is obtained by superimposing the camera offset difference ΔC on the reference. The residual drift on the upper camera side and the residual drift on the lower camera side are represented under the same reference, which can ensure the consistency of the reference in subsequent coordinate chains.

[0084] In this embodiment, the controller, based on the alignment deviation ΔP, controls the bonding head 11 and the worktable 8 to perform fine adjustments respectively. Wherein: Compensation amount for bond head fine-tuning = ΔP head k·ΔP; Workbench compensation amount = ΔP chuck +(1 k)·ΔP.

[0085] In this embodiment, ΔP head ΔP chuck The residual drift amounts on the upper and lower camera sides are fully compensated by the corresponding actuators and are not included in the allocation; only the alignment deviation ΔP under the unified reference coordinate system is allocated between the two actuators (bonding head and worktable) according to k.

[0086] In the formula, k is the distribution coefficient, which can be determined based on the stiffness and stroke of the bonding head 11 and the worktable 8. Specifically, the distribution coefficient k ranges from [0,1], representing the distribution ratio of the alignment deviation ΔP between the bonding head and the worktable. The method for determining k is as follows: First, determine the baseline allocation coefficient k0. Let the stiffness of the bond head fine-tuning mechanism be k. h The rigidity of the worktable is k. c (Unit: N / μm, measurement direction is consistent with compensation motion direction), then the reference allocation coefficient k0 is determined by the following formula: k0=k h / (k h +k c That is, based on the principle that the elastic deformation caused by the compensating motion on both sides is roughly equal, the side with higher stiffness bears a larger proportion of the compensation. h k c As an inherent property of the execution device, it does not change with operation and can be pre-calibrated through testing or by taking the design value of the device.

[0087] Secondly, the allocation coefficient k is determined based on the travel distance and the baseline allocation coefficient k0. Let S... h S cThe rated strokes of bonding head 11 and worktable 8 are deducted from the strokes already used in previous compensations, and ΔP in this compensation is deducted according to the worst-case scenario of superposition in the same direction. head ΔP chuck The available travel margin after the item.

[0088] To ensure that neither side exceeds the travel limit, k·|ΔP|≤S must be satisfied. h And (1) k)·|ΔP|≤S c The final result is: k=clip(k0,k min ,k max ), that is, k = min{k max max(k0,k min )}, where k max =S h / |ΔP|,k min =1 S c / |ΔP|.

[0089] k max k min The value of S is determined based on the measured bond bonding of that particular bond. h S c And |ΔP| is calculated in real time. When |ΔP|>S h +S c When the feasible interval is empty, k has no feasible value, the lockout compensation output is triggered and an alarm is triggered; when |ΔP| is less than the preset dead zone threshold (e.g., 0.05μm), compensation is not performed, and k does not participate in the calculation.

[0090] Furthermore, after adjusting the positions of the bonding head 11 and the stage 8, the controller controls the bonding head 8 to perform wafer bonding. After completing one bonding operation and picking up the next chip to be bonded, the above camera offset difference calculation process is repeated, so that the camera offset difference corresponding to each bonding operation is obtained by decoupling the online observation and differential measurement before that bonding operation, thereby ensuring the accuracy and stability of each wafer bonding operation.

[0091] refer to Figure 5 , Figure 5 This is a schematic diagram illustrating the working principle of a wafer bonding apparatus provided in one embodiment of this application. First, the bonding head 11 is moved from the film expansion machine (… Figure 5(Not shown in the image) The chip is removed, and the bonding head 11 and the upper camera 1 move along the upper camera guide rail 5 to above the first reference frame 3 and the second reference frame 4. The lower camera 2 moves along the lower camera guide rail 6 to below the first reference frame 3 and the second reference frame 4, thus placing the first reference frame 3 and the second reference frame 4 in the area where the fields of view of the upper and lower cameras intersect. The camera offset difference is calculated using the method described in the above embodiment, and the positions of the bonding head 11 and the stage 8 are adjusted according to the camera offset difference. After the bonding head 11 and the upper camera 1 move above the wafer 12, the bonding head 11 is controlled to perform wafer bonding. The wafer 12 is clamped by the clamping fixture 9. When fine-tuning the stage 8, the clamping fixture 9 can be controlled to move along the guide rail 10 of the clamping fixture. The above process can be performed before each wafer bonding to ensure that the wafer bonding error does not accumulate, thereby improving the alignment accuracy of the wafer bonding.

[0092] refer to Figure 6 , Figure 6 This is a flowchart illustrating a method for determining camera offset difference during wafer bonding according to an embodiment of this application. The method may include: S101: Obtain the image of the upper side of the first reference frame and the second reference frame taken by the upper camera in the wafer bonding equipment, and obtain the image of the lower side of the first reference frame and the second reference frame taken by the lower camera in the wafer bonding equipment.

[0093] Two reference frames are arranged side by side in the field of view of the two cameras; target plates are evenly distributed on the two opposite sides of the end of the first reference frame and the two opposite sides of the end of the second reference frame.

[0094] In this embodiment, reference Figure 4 The images captured by the upper and lower cameras include: the coordinates of the first target plate A obtained by the upper camera shooting from above the upper side of the first reference frame; the coordinates of the third target plate C obtained by the upper camera shooting from above the upper side of the second reference frame; the coordinates of the second target plate B obtained by the lower camera shooting from below the lower side of the first reference frame; and the coordinates of the fourth target plate D obtained by the lower camera shooting from below the lower side of the second reference frame. The first target plate A and the second target plate B are two opposite sides of the first reference frame, and the third target plate C and the fourth target plate D are two opposite sides of the second reference frame.

[0095] S102: For each reference frame, determine the actual position of the target plate on the upper side of the reference frame based on the shooting results, and calculate the first deviation between the actual position of the target plate and the standard position.

[0096] In this embodiment, the shooting results include the shooting results of the upper camera and the shooting results of the lower camera. The shooting results of the upper camera include the coordinates of the first target plate A and the third target plate C, and the coordinates of A and C are obtained based on the same coordinate system; the shooting results of the lower camera include the coordinates of the second target plate B and the fourth target plate D, and the coordinates of B and D are obtained based on the same coordinate system.

[0097] Ideally, if the heat generated by the camera moving on the guide rail is not considered, the actual position of each target plate can be calculated based on its coordinates. However, the camera's movement on the guide rail generates frictional heat. In addition, the wafers also generate heat during bonding, which affects the actual position of the target plates captured by the camera through the wafer bonding equipment's stage. Therefore, this embodiment first determines the actual position of the target plates based on the coordinates of each target plate in the imaging results and the following offset, and then calculates the deviation between the actual position and the standard position (i.e., the cold calibration value), making the final calculated camera offset difference more accurate.

[0098] In one implementation, determining the actual position of the target plate on the upper side of the reference frame based on the shooting results includes: S1021: Determine the first offset based on the temperature of the upper camera and the temperature of the guide rail corresponding to the upper camera.

[0099] S1022: Based on the position of the target plate in the shooting results of the upper camera and the first offset, determine the actual position of the target plate on the upper side of the reference frame.

[0100] In this embodiment, since the first reference frame is connected to the outer frame of the wafer bonding equipment and the second reference frame is connected to the table surface of the wafer bonding equipment, the upper and lower cameras change their shooting positions by moving on their respective guide rails. Therefore, the change in the temperature of the guide rails will change the actual position of the camera, thereby affecting the position coordinates of each reference frame in the shooting result.

[0101] In this embodiment, the intrinsic parameter offset of the upper camera can be calculated based on the temperature of the upper camera, and the offset of the guide rail corresponding to the upper camera can be calculated based on the temperature of the guide rail corresponding to the upper camera. The first offset can be calculated based on the intrinsic parameter offset of the upper camera and the offset of the guide rail corresponding to the upper camera, and then the actual position of the target plate on the upper side of the reference frame can be calculated. The specific calculation process can be referred to the above embodiment, and will not be repeated here.

[0102] S103: Determine the actual position of the target plate on the lower side of the reference frame based on the shooting results, and calculate the second deviation between the actual position of the target plate and the standard position.

[0103] In one implementation, determining the actual position of the target plate on the lower side of the reference frame based on the shooting results includes: S1031: Determine the second offset based on the temperature of the lower camera, the temperature of the guide rail corresponding to the lower camera, and the temperature of the worktable.

[0104] S1032: Based on the position of the target plate in the shooting results of the lower camera and the second offset, determine the actual position of the target plate on the lower side of the reference frame.

[0105] In this embodiment, the intrinsic parameter offset of the lower camera can be calculated based on the temperature of the lower camera, the offset of the guide rail corresponding to the lower camera can be calculated based on the temperature of the guide rail corresponding to the lower camera, and the reference offset of the worktable can be calculated based on the temperature of the worktable. The second offset can be calculated based on the intrinsic parameter offset of the lower camera, the offset of the guide rail corresponding to the lower camera, and the reference offset of the worktable. Then, the actual position of the target plate on the lower side of the reference frame can be calculated. The specific calculation process can be referred to the above embodiment, and will not be repeated here.

[0106] In this embodiment, the execution order of steps S102 and S103 can be interchanged, and no limitation is made here.

[0107] S104: Determine the initial camera offset difference between the two cameras when shooting the reference frame based on the first deviation and the second deviation.

[0108] In this embodiment, the specific calculation process for calculating the initial camera offset difference based on the first deviation and the second deviation can be referred to the above embodiment, and will not be repeated here.

[0109] S105: Determine the camera offset difference during this wafer bonding based on the initial camera offset difference when the two cameras take pictures of each reference frame.

[0110] In this embodiment, the process for determining the camera offset difference during wafer bonding is referenced. Figure 7 : S1051: For each camera, based on the standard position and actual position of the two target plates respectively in the camera's shooting results, determine the displacement of the target plate in the camera's shooting results.

[0111] S1052: Determine the average displacement of the target plate based on the displacement of the target plate in the shooting results of each camera.

[0112] S1053: Does the average displacement exceed the first displacement threshold? If the average displacement does not exceed the first displacement threshold, proceed to step S1054: determine the initial camera offset difference as the camera offset difference. If the average displacement exceeds the first displacement threshold, proceed to step S1055: control each camera to re-capture the target plate of the first and second reference frames.

[0113] S1056: Determine the updated initial camera offset difference and the updated average displacement based on the reshot results.

[0114] S1057: If the updated average displacement does not exceed the preset second displacement threshold, then the updated initial camera offset difference is determined as the camera offset difference.

[0115] S1058: If the updated average displacement exceeds the preset second displacement threshold, the compensation output will be locked and an alarm will be issued for maintenance.

[0116] As can be seen from the above, the first and second reference frames are arranged side by side in the field of view intersection area of ​​the upper and lower cameras, and both are fixed components of the bonding device. During the acquisition of the shooting results, there is no need to move the offline calibration tool into or out of this field of view intersection area. Therefore, the shooting results acquired by the upper and lower cameras before each bonding are all taken from the same set of common geometric references under the same online observation, eliminating the time difference between the offline calibration file and the current bonding condition. This ensures that the position of the target plate in the shooting results can reflect the real-time geometric state at the time of bonding, thus guaranteeing the timeliness and accuracy of the alignment reference.

[0117] The first offset is determined by the temperature of the upper camera and the temperature of the guide rail corresponding to the upper camera. The second offset is determined by the temperature of the lower camera, the temperature of the guide rail corresponding to the lower camera, and the temperature of the worktable. Thus, the camera intrinsic parameter drift on the upper camera side and the thermal expansion of the guide rail, the camera intrinsic parameter drift on the lower camera side, the thermal expansion of the guide rail, and the thermal expansion of the worktable are first subtracted from each coordinate chain. The remaining amounts are then used for differential calculation of the camera offset difference. The camera offset difference is obtained by cross-differentiation between the difference in position of the same reference frame in the results of two camera shots and the difference in position of the same camera in the results of two reference frames. Based on this, the residual drift of the upper and lower cameras after first-order correction can be separated from the relative micro-motion between the two reference frames, avoiding the overlap of the mechanical displacement of the motion stage and the structural thermal expansion in the visual coordinates.

[0118] In addition, this embodiment compares the average displacement of the target plate in the results of each camera's capture with a first displacement threshold: if the average displacement does not exceed the first displacement threshold, the initial camera offset difference is directly determined as the camera offset difference corresponding to this bonding operation; if it exceeds the first displacement threshold, each camera is controlled to re-capture the target plate of the first and second reference frames, and the updated initial camera offset difference and the updated average displacement are used to determine the camera offset difference. This distinguishes between transient anomalies in the observation stage and slippage or loosening of the reference frame components, preventing abnormal observation values ​​from entering the compensation link and negatively reducing alignment accuracy. All the above steps are performed for the current bonding operation, and the camera offset difference is updated in real time with each observation, matching the continuous temperature rise process of the equipment from standby to full load. Subsequent adjustments to the position of the bonding head and the worktable are consistent with the current working conditions, alleviating the problem of the disconnect between discrete level compensation and continuous dynamic temperature rise, and further improving the accuracy of wafer bonding.

[0119] Based on the camera offset difference determination method during wafer bonding in the above embodiments, this application provides a wafer bonding method in one embodiment, referencing... Figure 8 It includes the following steps: S201: The camera offset difference is obtained using the camera offset difference determination method.

[0120] S202: Control the upper camera to move on the corresponding guide rail to take pictures of the wafer to be bonded, and control the lower camera to move on the corresponding guide rail to take pictures of the chip to be bonded.

[0121] S203: Adjusts the position of the bonding head and the stage based on the camera offset difference, and controls the bonding head to perform wafer bonding.

[0122] Furthermore, the camera offset difference includes the upper camera offset difference and the lower camera offset difference; reference Figure 9 Step S203 specifically includes: S2031: Summing the camera offset difference and the residual drift on the upper camera side yields the residual drift on the lower camera side.

[0123] S2032: Determine the actual position of the wafer based on the wafer's position, first offset, and residual drift on the upper camera side in the upper camera's shooting results.

[0124] S2033: Determine the actual position of the chip based on the chip's position in the lower camera's shooting results, the second offset, and the residual drift on the lower camera side.

[0125] S2034: Determine alignment deviation based on the actual position of the chip and the actual position of the wafer.

[0126] S2035: Adjust the position of the key head and the position of the worktable based on the alignment deviation.

[0127] S2036: Control the bonding head to perform wafer bonding.

[0128] The specific methods and formulas for calculating the camera offset difference, determining the actual position of the wafer, determining the actual position of the chip, calculating the alignment deviation, and adjusting the position of the bonding head and the stage based on the alignment deviation in this embodiment can be found in the above embodiment, and will not be repeated here.

[0129] Based on the wafer bonding equipment in the above embodiments, this embodiment provides a wafer bonding alignment device, including an upper camera, a lower camera, a first reference frame, and a second reference frame.

[0130] The first and second reference frames are arranged side-by-side in the field of view intersection area of ​​the two cameras; target plates are evenly distributed on the two opposite ends of the first reference frame and the two opposite ends of the second reference frame. The arrangement of each target plate on the reference frame, the low-expansion connection method between the two target plates, and the center distance between the two reference frames are described in the above embodiment and will not be repeated here.

[0131] The upper and lower cameras are used to photograph the target plate to obtain the photographic results, so that the camera offset difference corresponding to wafer bonding can be determined based on the photographic results before wafer bonding.

[0132] In this embodiment, the first reference frame is connected to the outer frame of the wafer bonding equipment, and the second reference frame is connected to the worktable surface of the wafer bonding equipment. The upper and lower cameras change their shooting positions by moving on their respective guide rails. In this embodiment, the device also includes a temperature sensor array, including a first temperature sensor disposed on the housing of the upper camera, a second temperature sensor disposed on the housing of the lower camera, a third temperature sensor disposed on the guide rail corresponding to the upper camera, a fourth temperature sensor disposed on the guide rail corresponding to the lower camera, and a fifth temperature sensor disposed on the worktable. The controller is communicatively connected to the above-mentioned temperature sensors and is configured to calculate the camera offset difference based on the temperature data of the above sensors, the position of the target plate in the shooting result of the upper camera, and the position of the target plate in the shooting result of the lower camera, and adjust the position of the bonding head and the position of the worktable based on the camera offset difference to meet the alignment accuracy requirements of wafer bonding.

[0133] See Figure 10 , Figure 10 This is a schematic block diagram of a wafer bonding control device provided in one embodiment of this application. Figure 10The wafer bonding control device 1000 shown in this embodiment may include one or more processors 1001, one or more input devices 1002, one or more output devices 1003, and one or more memories 1004. The processors 1001, input devices 1002, output devices 1003, and memories 1004 communicate with each other via a communication bus 1005. The memories 1004 store computer programs, including program instructions. The processors 1001 execute the program instructions stored in the memories 1004. Specifically, the processors 1001 are configured to invoke the program instructions to execute the steps of the camera offset difference determination method or the wafer bonding method described above.

[0134] It should be understood that, in the embodiments of this application, the processor 1001 may be a central processing unit (CPU), or it may 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. A general-purpose processor may be a microprocessor or any conventional processor.

[0135] Input device 1002 may include a touchpad, a fingerprint sensor (for collecting the user's fingerprint information and fingerprint orientation information), a microphone, etc., and output device 1003 may include a display (LCD, etc.), a speaker, etc.

[0136] The memory 1004 may include read-only memory and random access memory, and provides instructions and data to the processor 1001. A portion of the memory 1004 may also include non-volatile random access memory. For example, the memory 1004 may also store device type information.

[0137] In specific implementations, the processor 1001, input device 1002, and output device 1003 described in the embodiments of this application can execute the implementation methods described in the camera offset difference determination method or wafer bonding method provided in the embodiments of this application, or they can execute the implementation methods of the wafer bonding control device described in the embodiments of this application, which will not be repeated here.

[0138] In another embodiment of this application, a computer-readable storage medium is provided. This computer-readable storage medium stores a computer program, which includes program instructions. When executed by a processor, the program instructions implement all or part of the processes in the methods described above. Alternatively, the computer program can instruct related hardware to complete the process. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include any entity or device capable of carrying computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0139] The computer-readable storage medium can be an internal storage unit of the wafer bonding control apparatus in any of the foregoing embodiments, such as a hard disk or memory of the wafer bonding control apparatus. The computer-readable storage medium can also be an external storage device of the wafer bonding control apparatus, such as a plug-in hard disk, SmartMedia Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the wafer bonding control apparatus. Furthermore, the computer-readable storage medium can include both internal storage units and external storage devices of the wafer bonding control apparatus. The computer-readable storage medium is used to store computer programs and other programs and data required by the wafer bonding control apparatus. The computer-readable storage medium can also be used to temporarily store data that has been output or will be output.

[0140] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this application.

[0141] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the wafer bonding control equipment and unit described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0142] In the several embodiments provided in this application, it should be understood that the disclosed wafer bonding control device and method can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces or units, or it may be an electrical, mechanical, or other form of connection.

[0143] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of this application, depending on actual needs.

[0144] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0145] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions.

[0146] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A wafer bonding apparatus, characterized in that, include: Upper camera, lower camera, first reference frame, second reference frame, and controller; The first reference frame and the second reference frame are arranged side by side in parallel in the field of view intersection area of ​​the two cameras; Target plates are evenly distributed on the two opposite ends of the first reference frame and the two opposite ends of the second reference frame; The controller is configured to, before each wafer bonding operation, control the upper camera to take a top-down view of the target plates on the upper sides of the two reference frames, and control the lower camera to take a bottom-up view of the target plates on the lower sides of the two reference frames; for each reference frame, determine the actual position of the target plate on the upper side of the reference frame based on the shooting results, and calculate a first deviation between the actual position of the target plate and a standard position; determine the actual position of the target plate on the lower side of the reference frame based on the shooting results, and calculate a second deviation between the actual position of the target plate and a standard position; and determine the initial camera offset difference between the two cameras when shooting the reference frame based on the first deviation and the second deviation. The camera offset difference during wafer bonding is determined based on the initial camera offset difference when the two cameras capture images of each reference frame; the position of the bonding head and the position of the worktable are adjusted based on the camera offset difference. The controller is also used to control the bonding head to perform wafer bonding after adjusting the position of the bonding head and the position of the worktable.

2. The wafer bonding equipment as described in claim 1, characterized in that, The first reference frame is mounted on the outer frame of the wafer bonding equipment via a floating thermal insulation support, and the second reference frame is mounted on the worktable of the wafer bonding equipment; the upper camera and the lower camera change their shooting positions by moving on their respective guide rails; the shooting results include the shooting results of the upper camera and the shooting results of the lower camera; The controller is specifically used to determine the actual position of the target plate on the upper side of the reference frame based on the shooting results and in the following manner: The first offset is determined based on the temperature of the upper camera and the temperature of the guide rail corresponding to the upper camera. Based on the position of the target plate in the shooting results of the upper camera and the first offset, the actual position of the target plate on the upper side of the reference frame is determined. The controller is specifically used to determine the actual position of the target plate on the lower side of the reference frame based on the shooting results and in the following manner: The second offset is determined based on the temperature of the lower camera, the temperature of the guide rail corresponding to the lower camera, and the temperature of the worktable. Based on the position of the target plate in the shooting results of the lower camera and the second offset, the actual position of the target plate on the lower side of the reference frame is determined.

3. The wafer bonding equipment as described in claim 2, characterized in that, The controller is specifically used to determine the first offset based on the following method: Based on the temperature of the upper camera, determine the positional offset caused by the thermal expansion of the upper camera at the temperature, resulting in the translation of the camera's optical center, and determine the internal imaging offset of the upper camera at the temperature. The intrinsic parameter offset of the upper camera is determined based on the position offset and internal imaging offset of the upper camera. Calculate the first temperature difference between the temperature of the guide rail corresponding to the upper camera and the standard reference temperature; The guide rail offset corresponding to the upper camera is obtained based on the distance between each target plate captured by the upper camera and the preset thermal expansion reference point of the guide rail and the first temperature difference. The first offset is obtained by summing the intrinsic parameter offset of the upper camera and the guide rail offset corresponding to the upper camera.

4. The wafer bonding equipment as described in claim 2, characterized in that, The controller is specifically used to determine the second offset based on the following method: Based on the temperature of the lower camera, determine the positional offset caused by the thermal expansion of the lower camera at the temperature, resulting in the translation of the camera's optical center, and determine the internal imaging offset of the lower camera at the temperature. The lower camera intrinsic parameter offset is determined based on the position offset and internal imaging offset of the lower camera. Calculate the second temperature difference between the temperature of the guide rail corresponding to the lower camera and the standard reference temperature; The guide rail offset corresponding to the lower camera is obtained based on the distance between each target plate captured by the lower camera and the preset thermal expansion reference point of the guide rail and the second temperature difference. Calculate the third temperature difference between the workbench temperature and the standard reference temperature; The reference offset of the worktable is obtained based on the distance between the thermal expansion reference center of the worktable and the preset alignment reference position and the third temperature difference; The second offset is obtained by summing the lower camera intrinsic parameter offset, the guide rail offset corresponding to the lower camera, and the worktable reference offset.

5. The wafer bonding equipment as described in claim 1, characterized in that, After calculating the initial camera offset difference, the controller is also used to: For each camera, based on the standard and actual positions of the two target plates in the camera's shooting results, the displacement of the target plate of each reference frame in the camera's shooting results is determined. The average displacement between the two reference frames is determined based on the displacements corresponding to the upper and lower cameras, respectively. When determining the camera offset difference based on the initial camera offset difference between the two cameras when capturing images of each reference frame, the controller is specifically used for: If the average displacement does not exceed the first displacement threshold, then the initial camera offset difference is determined as the camera offset difference; If the average displacement exceeds the first displacement threshold, then control each camera to re-capture the target plate of the first reference frame and the second reference frame, and determine the updated initial camera offset difference and the updated average displacement based on the re-capture results. If the updated average displacement does not exceed the preset second displacement threshold, then the updated initial camera offset difference is determined as the camera offset difference.

6. The wafer bonding equipment as described in claim 2, characterized in that, The controller is also used to: control the upper camera to move on the corresponding guide rail to control the upper camera to take pictures of the wafer to be bonded; and control the lower camera to move on the corresponding guide rail to control the lower camera to take pictures of the chip to be bonded. The controller adjusts the position of the bonding head and the position of the worktable through the following steps: The residual drift on the lower camera side is obtained by summing the camera offset difference and the residual drift on the upper camera side. Wherein, the residual drift on the upper camera side is the first deviation; The actual position of the wafer is determined based on the position of the wafer in the shooting results of the upper camera, the first offset, and the residual drift on the upper camera side; The actual position of the chip is determined based on the position of the chip in the shooting results of the lower camera, the second offset, and the residual drift on the lower camera side; The alignment deviation is determined based on the actual position of the chip and the actual position of the wafer; Adjust the position of the bonding head and the position of the worktable based on the alignment deviation.

7. The wafer bonding equipment as described in claim 1, characterized in that, The two target plates at the ends of the first reference frame and the two target plates at the ends of the second reference frame are connected by a material with a thermal expansion coefficient lower than the expansion coefficient threshold, so that the relative position of the two target plates of the same reference frame remains constant.

8. The wafer bonding equipment as described in claim 1, characterized in that, The center-to-center distance between the first reference frame and the second reference frame is no greater than the width of the intersection area of ​​the two camera fields of view in the side-by-side direction, and no less than the minimum effective shooting distance of a single camera for imaging a single reference frame.

9. A method for determining camera offset difference during wafer bonding, characterized in that, include: The image captures the upper side of the first and second reference frames by the upper camera in the wafer bonding equipment, and the image captures the lower side of the first and second reference frames by the lower camera in the wafer bonding equipment; wherein the two reference frames are arranged side by side in parallel in the field of view of the two cameras; target plates are evenly distributed on the two opposite ends of the first reference frame and the two opposite ends of the second reference frame. For each reference frame, the actual position of the target plate on the upper side of the reference frame is determined based on the shooting results, and the first deviation between the actual position of the target plate and the standard position is calculated; the actual position of the target plate on the lower side of the reference frame is determined based on the shooting results, and the second deviation between the actual position of the target plate and the standard position is calculated; the initial camera offset difference between the two cameras when shooting the reference frame is determined based on the first deviation and the second deviation. The camera offset difference during wafer bonding is determined based on the initial camera offset difference when the two cameras capture images of each reference frame.

10. The camera offset difference determination method as described in claim 9, characterized in that, The first offset is determined based on the temperature of the upper camera and the temperature of the guide rail corresponding to the upper camera; the second offset is determined based on the temperature of the lower camera, the temperature of the guide rail corresponding to the lower camera, and the temperature of the worktable. Determining the actual position of the target plate on the upper side of the reference frame based on the shooting results includes: determining the actual position of the target plate on the upper side of the reference frame based on the position of the target plate in the shooting results of the upper camera and the first offset. Determining the actual position of the target plate on the lower side of the reference frame based on the shooting results includes: determining the actual position of the target plate on the lower side of the reference frame based on the position of the target plate in the shooting results of the lower camera and the second offset.

11. A wafer bonding alignment apparatus, characterized in that, Includes an upper camera, a lower camera, a first reference frame, and a second reference frame; The first reference frame and the second reference frame are arranged side by side in parallel in the field of view intersection area of ​​the two cameras; Target plates are evenly distributed on the two opposite ends of the first reference frame and the two opposite ends of the second reference frame; The two target plates at the ends of the first reference frame and the two target plates at the ends of the second reference frame are connected by a material with a thermal expansion coefficient lower than the expansion coefficient threshold, so that the relative position of the two target plates of the same reference frame remains constant. The upper camera and the lower camera are used to capture images of the target plate to obtain images, so that the camera offset difference corresponding to wafer bonding can be calculated and determined based on the images before wafer bonding. The first reference frame is mounted on the outer frame of the wafer bonding equipment via a floating heat-insulating support, and the second reference frame is mounted on the worktable of the wafer bonding equipment; the upper camera and the lower camera change their shooting positions by moving on their respective guide rails.

12. A wafer bonding method, characterized in that, include: The camera offset difference is obtained using the camera offset difference determination method as described in claim 9 or 10; The upper camera is controlled to move on the corresponding guide rail to capture images of the wafer to be bonded, and the lower camera is controlled to move on the corresponding guide rail to capture images of the chip to be bonded. The position of the bonding head and the position of the worktable are adjusted based on the camera offset difference, and the bonding head is controlled to perform wafer bonding.

13. The wafer bonding method as described in claim 12, characterized in that, The adjustment of the position of the bonding head and the position of the worktable based on the camera offset difference includes: The residual drift on the lower camera side is obtained by summing the camera offset difference and the residual drift on the upper camera side. Wherein, the residual drift on the upper camera side is the first deviation; The actual position of the wafer is determined based on the position of the wafer, the first offset, and the residual drift on the upper camera side in the image captured by the upper camera; the first offset is determined based on the temperature of the upper camera and the temperature of the guide rail corresponding to the upper camera. The actual position of the chip is determined based on the position of the chip in the shooting results of the lower camera, the second offset, and the residual drift on the lower camera side; the second offset is determined based on the temperature of the lower camera, the temperature of the guide rail corresponding to the lower camera, and the temperature of the worktable; The alignment deviation is determined based on the actual position of the chip and the actual position of the wafer; Adjust the position of the bonding head and the position of the worktable based on the alignment deviation.

14. A wafer bonding control device, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the camera offset difference determination method as described in claim 9 or 10, or the steps of the wafer bonding method as described in claim 12 or 13.

15. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the camera offset difference determination method as described in claim 9 or 10, or the steps of the wafer bonding method as described in claim 12 or 13.

Images