A bonding device and a double-sided alignment method

Abstract

The present invention belongs to the field of wafer or chip bonding, and specifically relates to a bonding device and a double-sided alignment method. A double-sided alignment measurement system is provided to achieve high-precision alignment of wafers, chips, and wafers, and to perform high-precision compensation for horizontal offsets and rotation angles, thereby eliminating horizontal errors caused by vertical movement and eliminating horizontal position system deviations during measurement caused by the non-perpendicularity between the optical axis of the alignment system and the substrate surface.

Description

Technical Field

[0001] The present invention belongs to the field of wafer or chip bonding, and in particular relates to a bonding device and a double-sided alignment method. Background Art

[0002] In 3D interconnection, wafer-level packaging, wafer stacking, chip-to-chip stacking, and chip-to-wafer stacking, the alignment of two wafers, or two chips, or chip-to-wafer is a very important step. Alignment is mainly achieved by mechanical and optical means. In 3D integration, high offset accuracy is required after bonding, and optical alignment is adopted. Optical alignment is divided into back-side alignment and face-to-face alignment according to whether the substrate material is transparent and the position of the mark. Back-side alignment requires that one of the materials in the stacked substrates is transparent. If all materials are non-transparent, one material must be able to transmit infrared light. Face-to-face alignment has no restrictions on the materials of the stacked substrates, and visible light can be used for alignment illumination. However, the existing technology ignores the tilt caused by the vertical movement of the upper substrate driven by the moving table, and the angle with the optical axis will introduce alignment errors. In addition, when aligning the chuck, only single-point alignment is used, and the accuracy is low. Summary of the Invention

[0003] In view of this, the present invention provides a bonding device, which is equipped with a double-sided alignment measurement system, to achieve high-precision alignment of wafers, chips, and chips, and to perform high-precision compensation for horizontal offset and rotation angle, eliminating horizontal errors caused by vertical movement, and eliminating horizontal position system deviations during measurement caused by the non-perpendicularity of the optical axis of the alignment system to the substrate surface.

[0004] In order to achieve the above technical objectives, the specific technical solutions adopted by the present invention are:

[0005] A bonding device for bonding an upper substrate to a lower substrate;

[0006] The upper substrate and the lower substrate are both provided with corresponding substrate markings, and the substrate markings are used to mark the horizontal deviation between the upper substrate and the lower substrate;

[0007] The bonding device includes a vertical motion stage, a micro-motion compensation stage, a double-sided alignment measurement system, an upper reference plate, a lower reference plate and a machine vision system;

[0008] Before bonding, the upper substrate is placed on the vertical motion stage, and the lower substrate is mounted on the micro-motion compensation stage. The vertical motion stage is used to drive the upper substrate to move parallel to the lower substrate toward the lower substrate, and the micro-motion compensation stage is used to micro-adjust the posture of the lower substrate. The vertical motion stage is at a height before bonding;

[0009] The double-sided alignment measurement system includes a motion device and a double-sided photosensitive device; the motion device drives the double-sided photosensitive device to move parallel to the lower substrate between the vertical motion stage and the fine-motion compensation stage; the double-sided photosensitive device includes two groups of photosensitive elements with consistent optical axes and opposite photosensitive directions; the optical axis of the double-sided photosensitive device is perpendicular to the lower substrate;

[0010] The upper reference plate moves with the vertical motion stage and is provided with an upper reference mark; the lower reference plate is provided on the fine motion compensation stage and is provided with a lower reference mark; the upper reference mark and the lower reference mark correspond to each other and are used to identify the horizontal deviation between the vertical motion stage and the fine motion compensation stage;

[0011] The machine vision system is used to simultaneously photograph the upper reference mark and the lower reference mark when the vertical motion stage is at a bonding height for bonding the upper substrate and the lower substrate.

[0012] Furthermore, the lower reference plate is transparent, the machine vision system is arranged on the micro-motion compensation platform, and the optical axis of the machine vision system is perpendicular to the lower substrate and passes through the lower reference plate.

[0013] Furthermore, the upper substrate is transparent, the machine vision system is arranged on the vertical motion platform, and the optical axis of the machine vision system is perpendicular to the lower substrate and passes through the upper reference plate.

[0014] Furthermore, the upper reference plate is mounted on the vertical motion platform based on a first vertical adjustment device; the first vertical adjustment device is used to drive the upper reference plate to move perpendicularly to the lower substrate;

[0015] The lower reference plate is installed under the vertical motion platform based on a second vertical adjustment device; the second vertical adjustment device is used to drive the lower reference plate to move perpendicular to the lower substrate.

[0016] Furthermore, the upper reference plates are in two or more groups; the lower reference plates are in two or more groups.

[0017] Furthermore, the upper reference plates are rigidly connected to each other; and the lower reference plates are rigidly connected to each other.

[0018] Furthermore, the first vertical adjustment device consists of two or more groups, each driving the upper reference plate to move perpendicular to the lower substrate; the second vertical adjustment device consists of two or more groups, each driving the lower reference plate to move perpendicular to the lower substrate.

[0019] At the same time, the present invention also proposes a double-sided alignment method for performing bonding alignment when bonding an upper substrate and a lower substrate based on the above-mentioned bonding device, comprising the following steps:

[0020] S101: placing the vertical motion stage at the bonding height, measuring the upper reference mark and the lower reference mark based on the machine vision system, and obtaining a horizontal deviation between the vertical motion stage and the fine motion compensation stage at the bonding height;

[0021] S102: placing the vertical motion stage at the pre-bonding height, measuring the substrate mark, the upper reference mark, and the lower reference mark based on the double-sided alignment measurement system, to obtain a horizontal deviation between the upper substrate and the lower substrate before bonding, and a horizontal deviation between the upper reference plate and the lower reference plate before bonding;

[0022] Calculating the deviation of the bonding height between the upper substrate and the lower substrate based on the horizontal deviation of the vertical motion stage and the fine motion compensation stage at the bonding height, the horizontal deviation of the heights of the upper substrate and the lower substrate before bonding, and the horizontal deviation of the heights of the upper reference plate and the lower reference plate before bonding;

[0023] S103: Before bonding the upper substrate and the lower substrate, the deviation of the bonding height between the upper substrate and the lower substrate is compensated based on the micro-motion compensation stage to complete the alignment of the upper substrate and the lower substrate.

[0024] Furthermore, when measuring the substrate mark, upper reference mark and lower reference mark based on the double-sided alignment measurement system, the upper reference mark and the substrate mark on the upper substrate are in the same horizontal plane, and the lower reference mark and the mark on the lower substrate are in the same horizontal plane.

[0025] Furthermore, the horizontal deviation includes a horizontal offset and a deflection angle.

[0026] By adopting the above technical solution, the present invention can also bring the following beneficial effects:

[0027] The present invention provides a first vertical adjustment device and a second vertical adjustment device, which can enable the bonding device to adapt to wafers or chips of different thicknesses. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is a structural schematic diagram of a vertical motion platform of a bonding device at a height before bonding in a specific embodiment of the present invention;

[0030] Figure 2This is a structural schematic diagram of a vertical motion platform of a bonding device at a bonding height in a specific embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of a state in which the horizontal deviation between the upper substrate and the lower substrate and the horizontal deviation between the upper reference plate and the lower reference plate are measured when the vertical motion stage is at a height before bonding in a double-sided alignment method according to a specific embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram of a state of measuring the horizontal deviation between the upper reference plate and the lower reference plate when the vertical motion stage is at the bonding height in a double-sided alignment method according to a specific embodiment of the present invention;

[0033] Figure 5 This is a structural schematic diagram of a bonding device machine vision system arranged on a vertical motion platform in a specific embodiment of the present invention;

[0034] Among them: 1. Vertical motion stage; 11. Upper reference plate; 2. Micro-motion compensation stage; 21. Lower reference plate; 3. Double-sided alignment measurement system; 4. Machine vision system; 5. Upper substrate; 6. Lower substrate. DETAILED DESCRIPTION

[0035] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0036] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present invention, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement an apparatus and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this apparatus and / or practice this method.

[0038] It should also be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. The illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0039] Additionally, in the following description, specific details are provided to provide a thorough understanding of the examples. However, one skilled in the art will appreciate that the aspects described can be practiced without these specific details.

[0040] In one embodiment of the present invention, a bonding device is provided for performing bonding between an upper substrate 5 and a lower substrate 6; Figure 1-5 As shown, the upper substrate 5 and the lower substrate 6 are provided with corresponding substrate marks, which are used to mark the horizontal deviation between the upper substrate 5 and the lower substrate 6;

[0041] The bonding device includes a vertical motion stage 1, a micro-motion compensation stage 2, a double-sided alignment measurement system 3, an upper reference plate 11, a lower reference plate 21 and a machine vision system 4;

[0042] Before bonding, the upper substrate 5 is placed on the vertical motion stage 1, and the lower substrate 6 is mounted on the micro-motion compensation stage 2. The vertical motion stage 1 is used to drive the upper substrate 5 to move parallel to the lower substrate 6 toward the lower substrate 6; the micro-motion compensation stage 2 is used to micro-adjust the position of the lower substrate 6; the vertical motion stage 1 is at the height before bonding;

[0043] The double-sided alignment measurement system 3 includes a motion device and a double-sided photosensitive device. The motion device drives the double-sided photosensitive device to move parallel to the lower substrate 6 between the vertical motion stage 1 and the fine-motion compensation stage 2. The double-sided photosensitive device includes two sets of photosensitive elements with the same optical axis and opposite photosensitive directions. The optical axis of the double-sided photosensitive device is perpendicular to the lower substrate 6.

[0044] The upper reference plate 11 moves with the vertical motion stage 1 and is provided with an upper reference mark. The lower reference plate 21 is provided on the fine motion compensation stage 2 and is provided with a lower reference mark. The upper reference mark and the lower reference mark correspond to each other and are used to indicate the horizontal deviation between the vertical motion stage 1 and the fine motion compensation stage 2.

[0045] The machine vision system 4 is used to simultaneously photograph the upper reference mark and the lower reference mark when the vertical motion stage 1 is at a bonding height for bonding the upper substrate 5 and the lower substrate 6 .

[0046] In this embodiment, the upper substrate is a wafer or a chip, and the lower substrate is a wafer or a chip.

[0047] There are two implementation options for the double-sided alignment measurement system 3 of this embodiment. The first is to use back-to-back binocular telecentric cameras to calibrate the non-common-view binocular cameras to achieve camera pose calibration. The substrate markings of the upper substrate 5 and the lower substrate 6 can use the same marking pattern, and the upper reference mark and the lower reference mark can use the same marking pattern. The second is to use an optical lens to project the image on the other side onto the target surface of the same telecentric camera to achieve imaging in the same image. However, the substrate markings of the upper substrate 5 and the lower substrate 6 need to use yin and yang marking patterns respectively, and the upper reference mark and the lower reference mark need to use yin and yang marking patterns respectively to prevent overlap between the images. This double-sided measurement system can move horizontally and measure the marks on the substrate within the travel range.

[0048] In one embodiment, Figure 1 、 2 As shown in , 3 and 4 , the lower reference plate 21 is transparent, the machine vision system 4 is arranged on the micro-motion compensation platform 2 , and the optical axis of the machine vision system passes through the lower reference plate 21 perpendicular to the lower substrate 6 .

[0049] The upper reference mark of this embodiment is set on the side of the upper reference plate 11 close to the micro-motion compensation stage 2, so as to keep the upper reference mark and the substrate mark on the upper substrate 5 at the same horizontal plane, so that both can be at the perception distance of the double-sided alignment measurement system 3 at the same time.

[0050] Similarly, the lower reference mark is set on the side of the lower reference plate 21 close to the vertical motion table 1, so as to keep the lower reference mark and the substrate mark on the lower substrate 6 at the same horizontal plane, so that both can be at the perception distance of the double-sided alignment measurement system 3 at the same time.

[0051] In one embodiment, Figure 5 As shown, the upper reference plate 11 is transparent, the machine vision system 4 is set on the vertical motion platform 1, and the optical axis of the machine vision system passes through the upper reference plate 11 perpendicular to the lower substrate 6.

[0052] In one embodiment, the upper reference plate 11 is mounted on the vertical motion platform 1 based on a first vertical adjustment device; the first vertical adjustment device is used to drive the upper reference plate 11 to move perpendicularly to the lower substrate 6;

[0053] The lower reference plate 21 is installed under the vertical motion platform 1 based on the second vertical adjustment device; the second vertical adjustment device is used to drive the lower reference plate 21 to move perpendicular to the lower substrate 6.

[0054] The first vertical motion platform 1 and the second vertical motion platform 1 of this embodiment can adjust the upper reference mark and the substrate mark on the upper substrate 5 of different thicknesses to be in the same plane, and adjust the lower reference mark and the substrate mark on the lower substrate 6 of different thicknesses to be in the same plane, so that the double-sided alignment measurement system 3 can sense at the same time, so that the bonding device can adapt to wafers or chips of different thicknesses.

[0055] In one embodiment, in order to ensure that the horizontal offset and the deflection angle can be measured, as shown in FIG. Figure 1-4 As shown, the upper reference plates 11 are in two or more groups; the lower reference plates 21 are in two or more groups.

[0056] In one embodiment, the upper reference plates 11 are rigidly connected to each other; and the lower reference plates 21 are rigidly connected to each other.

[0057] In one embodiment, the first vertical adjustment device consists of two or more groups, each driving the upper reference plate 11 to move perpendicular to the lower substrate 6; the second vertical adjustment device consists of two or more groups, each driving the lower reference plate 21 to move perpendicular to the lower substrate 6.

[0058] Based on the same inventive concept, an embodiment of the present invention further provides a double-sided alignment method for the above-mentioned bonding apparatus to perform bonding alignment when bonding the upper substrate 5 and the lower substrate 6, comprising the following steps:

[0059] S101: The vertical motion stage 1 is placed at a bonding height, and the upper reference mark and the lower reference mark are measured using the machine vision system 4 to obtain a horizontal deviation between the vertical motion stage 1 and the fine motion compensation stage 2 at the bonding height;

[0060] S102: The vertical motion stage 1 is positioned at a pre-bonding height, and the substrate mark, the upper reference mark, and the lower reference mark are measured using the double-sided alignment measurement system 3 to obtain a horizontal deviation between the upper substrate 5 and the lower substrate 6 before bonding, and a horizontal deviation between the upper reference plate 11 and the lower reference plate 21 before bonding.

[0061] Calculate the deviation of the bonding height between the upper substrate 5 and the lower substrate 6 based on the horizontal deviation of the bonding height between the vertical motion stage 1 and the fine motion compensation stage 2, the horizontal deviation of the height between the upper substrate 5 and the lower substrate 6 before bonding, and the horizontal deviation of the height between the upper reference plate 11 and the lower reference plate 21 before bonding.

[0062] S103: Before bonding the upper substrate 5 and the lower substrate 6, the deviation of the bonding height between the upper substrate 5 and the lower substrate 6 is compensated based on the fine motion compensation stage 2 to complete the alignment of the upper substrate 5 and the lower substrate 6.

[0063] In this embodiment, when measuring the substrate mark, upper reference mark and lower reference mark based on the double-sided alignment measurement system 3, the upper reference mark and the substrate mark on the upper substrate 5 are in the same horizontal plane, and the lower reference mark and the mark on the lower substrate 6 are in the same horizontal plane.

[0064] In this embodiment, the horizontal deviation includes a horizontal offset and a deflection angle.

[0065] In this embodiment, a face-to-face alignment method is adopted. Reference plates are arranged on both the left and right sides of the vertical motion stage 1 and the fine-motion compensation stage 2. One side of the upper reference plate 11 and the lower reference plate 21 is transparent, and the initial deviation of the vertical motion stage 1 and the fine-motion compensation stage 2, including the horizontal offset and the rotation angle, can be calibrated and measured. When bonding is performed after the alignment is completed, the two substrates are brought close together, and the horizontal deviation caused by the vertical movement when the two substrates are brought close together is eliminated based on the fine-motion compensation stage 2.

[0066] The machine vision system 4 can measure the deviation between the marking patterns of the upper reference plate 11 and the lower reference plate 21 with high precision, and then use the double-sided alignment system to measure the deviation between the marking patterns of the upper substrate 5 and the lower substrate 6. The double-sided alignment system can be used to calibrate the optical axis and the surface of the substrate that are not completely perpendicular during the horizontal movement, so as to eliminate the system error that the optical axis of the double-sided alignment lens is not completely perpendicular when it is installed; when the two substrates are vertically close to each other and are to be bonded, the deviation between the reference marks can be measured again by the machine vision system 4. The horizontal position deviation caused by the vertical movement of the substrates when they are close can be eliminated by the position reference between the reference marks and the horizontal adjustment amount of the substrate alignment, thereby improving the accuracy after the final bonding. The marking patterns are all on the surface of the substrate to be bonded. To adapt to wafers of different thicknesses, the upper and lower wafer chucks, the upper reference plate 11 and the lower reference plate 21 can all move vertically to adjust the substrate surface to the alignment focal plane, and align the reference plate surface with the substrate surface.

[0067] The present invention is further described below according to three implementation conditions:

[0068] Working condition 1:

[0069] This working condition adopts a face-to-face alignment method. The upper substrate 5 is placed on the substrate chuck of the vertical motion stage 1, with upper reference plates 11 on both sides. There are at least two sets of marking patterns on the reference plates. The vertical motion stage 1 is used to adjust the surface height of the upper substrate 5. It is only used for height adjustment and cannot move horizontally. The upper reference plate 11 is also provided with a vertical action mechanism to adjust the height of the reference plate surface relative to the surface of the upper substrate 5. A double-sided alignment measurement system 3 is provided in between. The measurement system is mainly used to measure the horizontal position deviation of the marking pattern of the upper and lower wafers, the upper reference plate 11 and the lower reference plate 21. The system deviation of the double-sided alignment measurement system 3 is corrected by the machine vision system 4 matched with the lower reference plate 21. There are two implementation schemes for the double-sided alignment measurement system 3. The first is to use a back-to-back binocular telecentric camera to calibrate the non-common-view binocular camera to achieve camera posture calibration. At this time, the upper and lower wafer marking patterns can use the same marking pattern. The second method is to use an optical lens to project the image on the other side onto the target surface of the same telecentric camera to achieve imaging in the same image, but the upper and lower marks need to use yin and yang mark patterns respectively to prevent overlap between the images. The double-sided measurement system can move horizontally and measure the marks on the substrate within the travel range. The lower substrate 6 is placed on the micro-alignment deviation compensation table, which can perform horizontal micro-movement (X, Y, Rz) and vertical movement. The vertical movement is used to adjust the surface of the lower substrate 6 to the focal plane of the machine vision system 4. At the same time, a vertical action mechanism is provided to adjust the height deviation between the lower reference plate 21 and the surface of the lower substrate 6. The lower reference plate 21 is made of transparent material and is provided with at least two sets of marks, which are the same set of marks as the upper reference plate 11. The lower reference plate 21 is equipped with a machine vision system 4, one for each marker. This system measures the positional deviation between the upper and lower reference plates 11, 21 after they are brought into close proximity. The positional deviations of the multiple markers are then used to calculate the deflection angle between the vertical motion stage 1 and the fine-motion alignment compensation stage. The machine vision system 4 on the lower reference plate 21 is fixed to the lower reference plate 21 and moves with the vertical position adjustment mechanism of the lower reference plate 21. The left and right sides of the upper and lower reference plates 11, 21 are connected by a fixed structure. If the left and right sides tilt during vertical movement, this will introduce horizontal position deviation, which can be measured using a binocular alignment system.

[0070] The specific measurement steps are as follows:

[0071] Step 1: Calibrate the upper reference plate 11 and the lower reference plate 21. Figure 2As shown, the vertical motion stage 1 is moved so that the upper and lower reference plates 21 are close to each other, with a spacing of micrometers, so that the upper and lower reference marks are within the depth of field of the machine vision system 4. The left and right machine vision systems 4 capture the upper and lower reference mark patterns, and the deviation on the left is (Δx1, Δy1) and the deviation on the right is (Δx2, Δy2). The horizontal offset (T) between the upper and lower motion stages (vertical motion stage 1 and micro-compensation stage 2) can be obtained from the deviations on the left and right sides. sx ,T sy ) and the deflection angle Rsz (the distance between the left and right reference marks has been calibrated) are recorded as the initial offset value.

[0072] Step 2: Perform double-sided alignment, such as Figure 3 As shown. Based on the nominal positions of the upper substrate 5 and the lower substrate 6, the movement amount of the double-sided alignment system is calculated, and the vertical motion stage 1 moves upward so that the surface of the upper substrate 5 is in the alignment focal plane. The height of the fine-motion alignment deviation compensation stage is adjusted so that the upper surface of the lower substrate 6 is in the alignment focal plane. At the same time, the surface height of the upper reference plate 11 is adjusted to align it with the surface of the upper substrate 5; the surface height of the lower reference plate 21 is adjusted to align it with the surface of the lower substrate 6. The double-sided alignment measurement system 3 is moved between each pair of marks on the substrate and the reference plate to obtain the deviation between each mark. The deviation is calculated by measuring two or more groups of marks. Two groups of marks can be calculated directly, and the optimal solution for multiple groups of marks can be found by the least squares or LM method. The horizontal offset (T wx ,T wy ) and deflection angle Rwz, as well as the horizontal offset and deflection angle between the upper reference plate 11 and the lower reference plate 21. And according to the initial offset value of the reference plate, and the horizontal offset between the reference plates (T sx -T mx +T wx ,T sy -T my +T wy ) and deflection angle (Rsz-Rmz+Rwz), the horizontal offset and deflection angle between the substrates, and the horizontal offset and deflection angle of the reference plate when the final substrates are close and aligned are calculated as the alignment baseline.

[0073] Step 3: Figure 4 As shown, the double-sided alignment measurement system 3 is removed, and the fine-motion alignment deviation compensation stage compensates for the substrate offset and deflection angle calculated in Step 2. When the surfaces of upper substrate 5 and lower substrate 6 are close together and the upper and lower fiducial marks are within the depth of field of machine vision system 4, machine vision system 4 can monitor whether the executed offset and deflection angle are consistent with the alignment baseline. If there is any error, further fine-tuning can be performed. Finally, vertical motion stage 1 makes a small movement to the bonding height, and bonding is performed.

[0074] The error term introduced in this working condition is as follows:

[0075] (1) The repeatability error of the two-sided alignment measurement system 3 is mainly caused by the repeatability error of the two-sided alignment measurement system 3 itself and the measurement error caused by the repeatability of the movement of the two-sided alignment measurement system 3;

[0076] (2) Repeatability error of measurement by machine vision system 4

[0077] Working condition 2

[0078] The difference between this working condition and working condition 1 is that the machine vision is placed on the vertical motion platform 1, such as Figure 5 As shown, the structure of the micro-alignment deviation compensation stage can be made more compact. The upper reference plate 11 is made of transparent material, which facilitates the machine vision system 4 to simultaneously capture the alignment marks of the upper reference plate 11 and the lower reference plate 21.

[0079] Step 1: Calibrate the upper reference plate 11 and the lower reference plate 21. Move the vertical motion stage 1 so that the upper and lower reference plates 21 fit together, with a spacing at the micron level, so that the upper and lower reference marks are within the depth of field of the machine vision system 4. The machine vision system 4 captures the upper and lower reference mark patterns from the left and right sides of the vertical motion stage 1, and the deviation on the left is (Δx1, Δy1), and the deviation on the right is (Δx2, Δy2). The horizontal offset between the upper and lower motion stages (T sx ,T sy ) and the deflection angle Rsz (the distance between the left and right reference marks has been calibrated) are recorded as the initial offset value.

[0080] Step 2: Perform double-sided alignment. Based on the nominal positions of the upper substrate 5 and the lower substrate 6, calculate the movement of the double-sided alignment system, move the vertical motion stage 1 upward, so that the surface of the upper substrate 5 is in the alignment focal plane, and adjust the height of the micro-alignment deviation compensation stage so that the upper surface of the lower substrate 6 is in the alignment focal plane. At the same time, adjust the surface height of the upper reference plate 11 to align it with the surface of the upper substrate 5; adjust the surface height of the lower reference plate 21 to align it with the surface of the lower substrate 6. Move the double-sided alignment measurement system 3 between each pair of marks on the substrate and the reference plate to obtain the deviation between each mark, measure two or more groups of marks to calculate the deviation, two groups of marks can be calculated directly, and multiple groups of marks can find the optimal solution through the least squares or LM method. The horizontal offset (T wx ,T wy ) and deflection angle Rwz, as well as the horizontal offset and deflection angle between the upper reference plate 11 and the lower reference plate 21. And according to the initial offset value of the reference plate, and the horizontal offset between the reference plates (T sx -T mx +T wx ,Tsy -T my +T wy ) and deflection angle (Rsz-Rmz+Rwz), the horizontal offset and deflection angle between the substrates, and the horizontal offset and deflection angle of the reference plate when the final substrates are close and aligned are calculated as the alignment baseline.

[0081] Step 3: Move the double-sided alignment measurement system 3 away, and use the fine-motion alignment deviation compensation table to compensate for the offset and deflection angle calculated in Step 2. Use the machine vision system 4 to control the executed offset and deflection angle, and move the vertical motion table 1 downward to the bonding height for bonding.

[0082] The error term of this working condition is the same as that of working condition 1.

[0083] Working condition 3

[0084] This working condition is different from working condition 1 in that there is no rigid connection between the upper reference plate 11 and the lower reference plate 21 and the marking plates, and the left and right marks on both sides of the reference plate have motion platforms that can perform vertical movement respectively. When the size of the substrate is large, the design can be made more compact. If the tilt caused by the vertical movement makes the height difference between the left and right reference plates greater than the camera depth of field of the binocular alignment system, it will result in the inability to measure the offset of the two marks at the same height. At this time, the mark vertical motion platform 1 can be used to vertically move the reference plates to adjust the height of the mark. The advantage of this working condition is that the structural design can be more compact, and the horizontal tilt requirement caused by the vertical movement of the vertical motion platform 1 can be lowered. However, this working condition introduces the tilt of the mark vertical motion platform 1 when it is performing vertical movement, which in turn causes horizontal deviation.

[0085] Step 1: Calibrate the upper reference plate 11 and the lower reference plate 21. The motion mark is vertical to the motion stage 1, so that the upper reference plate 11 and the lower reference plate 21 are aligned, and the spacing is at the micron level, so that the upper and lower reference marks are both within the depth of field of the machine vision system 4. The upper and lower reference mark patterns are photographed by the machine vision system 4 on the left and right of the fine alignment deviation compensation stage, and the deviation on the left is (Δx1, Δy1), and the deviation on the right is (Δx2, Δy2). The horizontal offset between the upper and lower motion stages (T sx ,T sy ) and the deflection angle Rsz (the distance between the left and right reference marks has been calibrated) are recorded as the initial offset value.

[0086] Step 2: Perform double-sided alignment. Based on the nominal positions of the upper substrate 5 and the lower substrate 6, calculate the movement of the double-sided alignment system. Move the vertical motion stage 1 upward so that the surface of the upper substrate 5 is in the alignment focal plane. Adjust the height of the micro-alignment deviation compensation stage so that the upper surface of the lower substrate 6 is in the alignment focal plane. Move the double-sided alignment measurement system 3 between each pair of marks on the substrate and the reference plate to obtain the deviation between each mark. Measure two or more groups of marks to calculate the deviation. Two groups of marks can be calculated directly, and multiple groups of marks can be used to find the optimal solution through the least squares or LM method. The horizontal offset (T wx ,T wy ) and deflection angle Rwz, as well as the horizontal offset and deflection angle between the upper reference plate 11 and the lower reference plate 21. By moving the reference plate vertical motion stage 1, the reference plate is placed within the depth of field of the binocular alignment measurement system. The binocular alignment measurement system is used to align the upper and lower reference marks, and the marks on the left and right sides of the upper reference plate 11 and the lower reference plate 21 are measured. The horizontal offset (T mx ,T my ) and deflection angle Rmz. And according to the initial offset value of the reference plate and the horizontal offset between the reference plates (T sx -T mx +T wx ,T sy -T my +T wy ) and deflection angle (Rsz-Rmz+Rwz), the horizontal offset and deflection angle between the substrates, and the horizontal offset and deflection angle of the reference plate when the final substrates are close and aligned are calculated as the alignment baseline.

[0087] Step 3: Figure 4 As shown, the double-sided alignment measurement system 3 is moved away, the fine-motion alignment deviation compensation stage compensates for the offset and deflection angle calculated in Step 2, and the offset and deflection angle are controlled by the machine vision system 4. The vertical motion stage 1 moves downward to the bonding height for bonding.

[0088] The error term of this working condition introduces the horizontal deviation of the marked vertical motion platform 1 during vertical motion, and the other error terms are the same as those of working condition 1.

[0089] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A bonding device for bonding an upper substrate to a lower substrate; characterized in that: The upper substrate and the lower substrate are both provided with corresponding substrate markings, and the substrate markings are used to mark the horizontal deviation between the upper substrate and the lower substrate; The bonding device includes a vertical motion stage, a micro-motion compensation stage, a double-sided alignment measurement system, an upper reference plate, a lower reference plate and a machine vision system; Before bonding, the upper substrate is placed on the vertical motion stage, and the lower substrate is mounted on the micro-motion compensation stage. The vertical motion stage is used to drive the upper substrate to move parallel to the lower substrate toward the lower substrate, and the micro-motion compensation stage is used to micro-adjust the posture of the lower substrate. The vertical motion stage is at a height before bonding; The double-sided alignment measurement system includes a motion device and a double-sided photosensitive device; the motion device drives the double-sided photosensitive device to move parallel to the lower substrate between the vertical motion stage and the fine-motion compensation stage; the double-sided photosensitive device includes two groups of photosensitive elements with consistent optical axes and opposite photosensitive directions; the optical axis of the double-sided photosensitive device is perpendicular to the lower substrate; The upper reference plate moves with the vertical motion stage and is provided with an upper reference mark; the lower reference plate is provided on the fine motion compensation stage and is provided with a lower reference mark; the upper reference mark and the lower reference mark correspond to each other and are used to identify the horizontal deviation between the vertical motion stage and the fine motion compensation stage; The machine vision system is used to simultaneously photograph the upper reference mark and the lower reference mark when the vertical motion stage is at a bonding height for bonding the upper substrate and the lower substrate.

2. The bonding device according to claim 1, wherein: The lower reference plate is transparent, the machine vision system is arranged on the micro-motion compensation platform, and the optical axis of the machine vision system is perpendicular to the lower substrate and passes through the lower reference plate.

3. The bonding device according to claim 1, wherein: The upper substrate is transparent, the machine vision system is arranged on the vertical motion platform, and the optical axis of the machine vision system is perpendicular to the lower substrate and passes through the upper reference plate.

4. The bonding device according to claim 1, wherein: The upper reference plate is mounted on the vertical motion platform based on a first vertical adjustment device; the first vertical adjustment device is used to drive the upper reference plate to move perpendicularly to the lower substrate; The lower reference plate is installed under the vertical motion platform based on a second vertical adjustment device; the second vertical adjustment device is used to drive the lower reference plate to move perpendicular to the lower substrate.

5. The bonding device according to claim 1, wherein: The upper reference plates are in groups of two or more; the lower reference plates are in groups of two or more.

6. The bonding device according to claim 5, wherein: The upper reference plates are rigidly connected to each other; and the lower reference plates are rigidly connected to each other.

7. The bonding device according to claim 4, wherein: The first vertical adjustment device consists of two or more groups, each driving the upper reference plate to move perpendicular to the lower substrate; the second vertical adjustment device consists of two or more groups, each driving the lower reference plate to move perpendicular to the lower substrate.

8. A double-sided alignment method for performing bonding alignment when bonding an upper substrate and a lower substrate based on the bonding device according to any one of claims 1 to 7, characterized in that: The following steps are involved: S101: placing the vertical motion stage at the bonding height, measuring the upper reference mark and the lower reference mark based on the machine vision system, and obtaining a horizontal deviation between the vertical motion stage and the fine motion compensation stage at the bonding height; S102: placing the vertical motion stage at the pre-bonding height, measuring the substrate mark, the upper reference mark, and the lower reference mark based on the double-sided alignment measurement system, to obtain a horizontal deviation between the upper substrate and the lower substrate before bonding, and a horizontal deviation between the upper reference plate and the lower reference plate before bonding; Calculating the deviation of the bonding height between the upper substrate and the lower substrate based on the horizontal deviation of the vertical motion stage and the fine motion compensation stage at the bonding height, the horizontal deviation of the heights of the upper substrate and the lower substrate before bonding, and the horizontal deviation of the heights of the upper reference plate and the lower reference plate before bonding; S103: Before bonding the upper substrate and the lower substrate, the deviation of the bonding height between the upper substrate and the lower substrate is compensated based on the micro-motion compensation stage to complete the alignment of the upper substrate and the lower substrate.

9. The double-sided alignment method according to claim 8, characterized in that: When measuring the substrate mark, upper reference mark and lower reference mark based on the double-sided alignment measurement system, the upper reference mark and the substrate mark on the upper substrate are in the same horizontal plane, and the lower reference mark and the mark on the lower substrate are in the same horizontal plane.

10. The double-sided alignment method according to claim 8, characterized in that: The horizontal deviation includes a horizontal offset and a deflection angle.

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