A multi-modal sensor based hybrid bonded wafer dynamic alignment system and method

Abstract

The application discloses a kind of hybrid bonding wafer dynamic alignment system and method based on multi-modal sensor, including hot-press bonding chamber, six degrees of freedom piezoelectric ceramic actuator, servo drive motor, flexible gripper, CCD camera, light source, infrared thermal imager, piezoelectric pressure sensor, laser differential interferometer, clamping force detection sensor and compensation controller, flexible gripper is fixedly connected with the output shaft of servo drive motor, and flexible gripper is used to clamp and fix upper wafer, six degrees of freedom piezoelectric ceramic actuator is used to compensate and adjust the position of upper wafer so that it is accurately aligned with lower wafer, CCD camera is respectively arranged at the two sides above upper wafer, light source is respectively arranged at the two sides below lower wafer, and the compensation amount Δx of upper wafer along X direction and the compensation amount Δy of Y direction are calculated by compensation controller.The technical scheme of the application can realize wafer real-time dynamic alignment under high temperature and high pressure environment, and inhibit bonding deviation caused by thermal expansion difference.

Description

Technical Field

[0001] This invention relates to the field of bonding equipment technology, and in particular to a hybrid bonding wafer dynamic alignment system and method based on multimodal sensors. Background Technology

[0002] Chip packaging is a crucial step in semiconductor manufacturing, providing physical protection, electrical interconnection, and heat dissipation for the chip. Bonding technology is the method of connecting a bare chip to external materials. The basic principle of thermocompression bonding is the same as that of traditional diffusion bonding: the Cu bumps of the upper and lower chips are aligned and then directly contacted. The main parameters affecting atomic diffusion bonding are temperature, pressure, and time. Wafer alignment accuracy is critical to thermocompression bonding and directly affects the chip packaging quality.

[0003] In chip packaging, the temperature of thermocompression bonding is typically between 300℃ and 400℃. The thermal expansion of two different wafer materials differs (e.g., silicon wafer CTE = 2.6 × 10⁻⁶ / ℃, glass substrate CTE = 8.5 × 10⁻⁶ / ℃). Currently, traditional bonding equipment mainly uses fixed clamping and positioning mechanisms (such as electrostatic chucks) to align and fix the wafers, and employs an infrared alignment system for static pre-alignment. However, fixed clamping and positioning mechanisms are prone to micron-level drift (>3μm) at high temperatures, and the infrared alignment system suffers from thermal noise interference in high-temperature environments. Furthermore, fixed clamping and positioning mechanisms cannot compensate for the dynamic deformation during the thermocompression bonding process and lack a temperature-stress coupling compensation mechanism, leading to wafer misalignment during thermocompression bonding, thus affecting wafer alignment accuracy and the quality of the thermocompression bonding. Summary of the Invention

[0004] The main objective of this invention is to propose a hybrid bonding wafer dynamic alignment system and method based on multimodal sensors, aiming to solve the problems mentioned in the background art, realize real-time dynamic alignment of wafers under high temperature and high pressure environment (accuracy ±0.5μm), and suppress bonding misalignment caused by thermal expansion differences.

[0005] To achieve the above objectives, this invention proposes a hybrid bonding wafer dynamic alignment system based on multimodal sensors for thermocompression bonding of a lower and upper wafer. The system includes a thermocompression bonding chamber, a six-degree-of-freedom piezoelectric ceramic actuator, a servo drive motor, flexible grippers, a CCD camera, a light source, an infrared thermal imager, a piezoelectric pressure sensor, a laser differential interferometer, a clamping force detection sensor, and a compensation controller. The lower wafer is adsorbed and fixed at the bottom of the thermocompression bonding chamber by a lower suction cup. The six-degree-of-freedom piezoelectric ceramic actuator is disposed on the inner top wall of the thermocompression bonding chamber, and the flexible grippers are respectively disposed on the upper and lower wafers. On both sides above the lower suction cup, the servo drive motor is connected to the output end of the six-degree-of-freedom piezoelectric ceramic actuator. The flexible gripper is fixedly connected to the output shaft of the servo drive motor. The flexible gripper is used to clamp and fix the upper wafer. The six-degree-of-freedom piezoelectric ceramic actuator is used to compensate and adjust the position of the upper wafer to make it precisely aligned with the lower wafer. The CCD camera is respectively set on both sides above the upper wafer. The light source is respectively set on both sides below the lower wafer. A light-transmitting cross-shaped alignment mark is provided on both sides of the upper end wall of the lower wafer. A light-transmitting cross-shaped alignment mark is provided on both sides of the upper end wall of the upper wafer. The alignment marks are aligned with opaque cross-shaped alignment marks. The light source is located directly below the translucent cross-shaped alignment marks. The CCD cameras are located directly above the opaque cross-shaped alignment marks. The CCD cameras and light source are used to verify whether the upper and lower wafers are aligned. The infrared thermal imager, piezoelectric pressure sensor, and compensation controller are disposed in the thermo-bonding chamber. The infrared thermal imager is used to measure the local temperature of the upper and lower wafers. The piezoelectric pressure sensor is used to measure the pressure applied between the upper and lower wafers. The laser differential interferometer and clamping force detector are also included. The sensor is installed inside the servo drive motor. The laser differential interferometer is used to measure the expansion of the upper wafer in the X and Y directions. The clamping force detection sensor is used to detect the clamping force of the flexible gripper. The compensation controller is electrically connected to the six-degree-of-freedom piezoelectric ceramic actuator, CCD camera, infrared thermal imager, piezoelectric pressure sensor, servo drive motor, laser differential interferometer, and clamping force detection sensor. The compensation controller calculates the compensation amount Δx in the X direction and the compensation amount Δy in the Y direction of the upper wafer and outputs it to the six-degree-of-freedom piezoelectric ceramic actuator for dynamic compensation.

[0006] Optionally, Δx and Δy are calculated using the following formulas:

[0007] Δx=α·L·(T-T0)+kx·(P-P0)

[0008] Δy=α·L·(T-T0)+ky·(P-P0)

[0009] Where α is the local thermal expansion coefficient of the wafer, determined according to the wafer material, L is the diameter of the wafer, kx and ky are the pressure deformation coefficients of the wafer in the X and Y directions, respectively, determined according to the elastic modulus of the wafer material, T is the local temperature of the wafer, T0 is the initial temperature of the wafer, T0 = 25℃, P is the local pressure of the wafer, P0 is the initial pressure of the wafer, P0 = 0MPa.

[0010] Optionally, it also includes a top plate, a drive plate, and an L-shaped mounting plate. The top plate is disposed on the inner top wall of the hot-press bonding chamber. The six-degree-of-freedom piezoelectric ceramic actuator is disposed on the lower end wall of the top plate. The drive plate is fixedly connected to the output end of the six-degree-of-freedom piezoelectric ceramic actuator. The L-shaped mounting plates are respectively disposed at both ends of the drive plate. The servo drive motor is disposed on the L-shaped mounting plate. The flexible grippers are all arranged in an arc shape.

[0011] Optionally, it also includes a flexible gripper fixing plate, which is fixedly connected to the output shaft of the servo drive motor. The flexible gripper is fixedly connected to the flexible gripper fixing plate. Multiple limiting blocks are protruding from the lower ends of the inner peripheral walls at both ends of the flexible gripper. The inner peripheral walls of the flexible gripper can abut against the outer peripheral wall of the upper wafer, and the limiting blocks can abut against the lower end wall of the edge of the upper wafer.

[0012] Optionally, it also includes a pressure roller arm, a pressure roller, and a push rod. The pressure roller arm is vertically movable and disposed on the outside of the flexible gripper. The pressure roller arm is rotatably connected to the flexible gripper fixing plate. The pressure roller is rotatably disposed on the lower end of the pressure roller arm. The push rod is slidably disposed on the L-shaped mounting plate. The front end of the push rod abuts against the pressure roller arm. The pressure roller can abut against the upper wafer.

[0013] Optionally, it also includes a support frame, a lifting cylinder, a U-shaped connector, and a pushing cylinder. The support frame is disposed on the upper wall of the flexible gripper fixing plate, the lifting cylinder is disposed on the upper end of the support frame, the pushing cylinder is disposed on the L-shaped mounting plate, the U-shaped connector is fixedly connected to the cylinder rod of the lifting cylinder, the upper end of the pressure roller arm is rotatably connected to the U-shaped connector through a short shaft, and the cylinder rod of the pushing cylinder is fixedly connected to the push rod.

[0014] Optionally, the line width of the translucent cross-shaped alignment mark and the opaque cross-shaped alignment mark ranges from 0.1 μm to 0.2 μm.

[0015] Optionally, the wavelength range of the light source includes the visible light band and the infrared band.

[0016] Optionally, the flexible gripper is made of shape memory alloy.

[0017] On the other hand, the present invention also proposes a wafer dynamic alignment method based on the above-mentioned hybrid bonding wafer dynamic alignment system based on multimodal sensors, the wafer dynamic alignment method comprising the following steps:

[0018] S1: Place the lower wafer on the lower suction cup and fix it by adsorption through the vacuum suction hole;

[0019] S2: The upper wafer is clamped and fixed by flexible grippers, and the upper wafer is aligned and fixed above the lower wafer to complete the coarse alignment of the upper and lower wafers. The upper wafer is pressed and adhered to the lower wafer by the upper suction cup. The thermo-bonding chamber is heated to the target temperature at a rate of 10℃ / s. Pressure is applied to the upper wafer through a three-stage pressurization method.

[0020] S3: Real-time data acquisition. The infrared thermal imager is used to measure the local temperature of the upper wafer to obtain an infrared thermal image. The local thermal expansion coefficient of the upper wafer is calculated based on the infrared thermal image. The expansion amount of the upper wafer in the X and Y directions is measured by a laser differential interferometer. The pressure between the upper and lower wafers is measured by a piezoelectric pressure sensor. The acquired data is then uploaded to the compensation controller.

[0021] S4: The compensation amounts Δx and Δy in the X and Y directions are calculated using the built-in algorithm of the compensation controller and output to the six-degree-of-freedom piezoelectric ceramic actuator;

[0022] S5: The six-degree-of-freedom piezoelectric ceramic actuator dynamically compensates for the position of the upper wafer based on the values ​​of the compensation amounts Δx and Δy.

[0023] S6: Verify the alignment accuracy between the upper and lower wafers using a CCD camera and a light source. When the CCD camera detects light from the light source, it indicates that there is an offset in the alignment between the upper and lower wafers. Repeat steps S3 to S6 until the CCD camera can no longer detect light from the light source. Then, the precise alignment between the upper and lower wafers is completed, and hot-press bonding begins.

[0024] The technical solution of this invention has the following beneficial effects: The technical solution of this invention can realize real-time dynamic alignment of wafers under high temperature and high pressure (accuracy ±0.5μm), suppress bonding offset caused by thermal expansion differences, perform nanometer-level position correction on wafers, solve the problem of wafer alignment mark recognition degradation under high temperature conditions, greatly improve wafer alignment accuracy, and realize high-precision dynamic alignment between chip wafers and substrate wafers in thermo-press bonding processes, meeting the ±0.5μm level alignment accuracy requirements of 3DIC integration and Chiplet heterogeneous packaging. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, 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 the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0026] Figure 1 This is a partial structural schematic diagram of a hybrid bonding wafer dynamic alignment system based on a multimodal sensor according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of another part of the structure of a hybrid bonding wafer dynamic alignment system based on a multimodal sensor according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of a portion of the structure of a hybrid bonding wafer dynamic alignment system based on a multimodal sensor according to an embodiment of the present invention.

[0029] Figure 4 This is a schematic diagram of a portion of the structure of a hybrid bonding wafer dynamic alignment system based on a multimodal sensor according to an embodiment of the present invention.

[0030] Figure 5 for Figure 4 Magnification at point A;

[0031] Figure 6 This is a schematic diagram of the lower wafer structure of a hybrid bonding wafer dynamic alignment system based on a multimodal sensor according to an embodiment of the present invention;

[0032] Figure 7 This is a flowchart illustrating the steps of a hybrid bonding wafer dynamic alignment method based on a multimodal sensor, according to an embodiment of the present invention.

[0033] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0036] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0037] This invention proposes a dynamic alignment system and method for hybrid bonding wafers based on multimodal sensors.

[0038] like Figures 1 to 7As shown, in one embodiment of the present invention, the hybrid bonding wafer dynamic alignment system based on multimodal sensors is used for thermo-bonding of a lower wafer 200 and an upper wafer 300. It includes a thermo-bonding chamber (not shown), a six-degree-of-freedom piezoelectric ceramic actuator 101, a servo drive motor 102, a flexible gripper 103, a CCD camera 104, a light source 105, an infrared thermal imager (not shown), a piezoelectric pressure sensor (not shown), a laser differential interferometer (not shown), a clamping force detection sensor (not shown), and a compensation controller (not shown). The lower wafer 200 is adsorbed and fixed to the bottom of the thermo-bonding chamber by a lower suction cup, and the six-degree-of-freedom piezoelectric ceramic actuator 101 is disposed on the inner top of the thermo-bonding chamber. On the wall, flexible grippers 103 are respectively disposed on both sides above the lower suction cup. A servo drive motor 102 is connected to the output end of a six-degree-of-freedom piezoelectric ceramic actuator 101. The flexible grippers 103 are fixedly connected to the output shaft of the servo drive motor 102. The flexible grippers 103 are used to clamp and fix the upper wafer 300. The six-degree-of-freedom piezoelectric ceramic actuator 101 is used to compensate and adjust the position of the upper wafer 300 so that it is precisely aligned with the lower wafer 200. CCD cameras 104 are respectively disposed on both sides above the upper wafer 300. Light sources 105 are respectively disposed on both sides below the lower wafer 200. A light-transmitting cross-shaped alignment mark 201 is provided on both sides of the upper end wall of the lower wafer 200. The upper end wall of the upper wafer 300... On both sides, there is an opaque cross-shaped alignment mark 301 corresponding to the translucent cross-shaped alignment mark 201. The light source 105 is located directly below the translucent cross-shaped alignment mark 201, and the CCD camera 104 is located directly above the opaque cross-shaped alignment mark 301. The CCD camera 104 and the light source 105 are used to verify whether the upper wafer 300 and the lower wafer 200 are aligned. An infrared thermal imager, a piezoelectric pressure sensor, and a compensation controller are set in the thermo-bonding chamber. The infrared thermal imager is used to measure the local temperature of the upper wafer 300 and the lower wafer 200, and the piezoelectric pressure sensor is used to measure the pressure applied between the upper wafer 300 and the lower wafer 200. A laser differential interferometer and a clamping device are also included. A force detection sensor is installed inside the servo drive motor 102. A laser differential interferometer is used to measure the expansion of the upper wafer 300 in the X and Y directions. A clamping force detection sensor is used to detect the clamping force of the flexible gripper 103. The compensation controller is electrically connected to the six-degree-of-freedom piezoelectric ceramic actuator 101, CCD camera 104, infrared thermal imager, piezoelectric pressure sensor, servo drive motor 102, laser differential interferometer, and clamping force detection sensor. The compensation controller calculates the compensation amount Δx in the X direction and the compensation amount Δy in the Y direction of the upper wafer 300 and outputs it to the six-degree-of-freedom piezoelectric ceramic actuator 101 for dynamic compensation and to verify whether the upper wafer 300 and the lower wafer 200 are accurately aligned.

[0039] Specifically, Δx and Δy are calculated using the following formulas:

[0040] Δx=α·L·(T-T0)+kx·(P-P0)

[0041] Δy=α·L·(T-T0)+ky·(P-P0)

[0042] Where α is the local thermal expansion coefficient of the wafer, determined according to the wafer material, L is the diameter of the wafer, kx and ky are the pressure deformation coefficients of the wafer in the X and Y directions, respectively, determined according to the elastic modulus of the wafer material, T is the local temperature of the wafer, T0 is the initial temperature of the wafer, T0 = 25℃, P is the local pressure of the wafer, P0 is the initial pressure of the wafer, P0 = 0MPa.

[0043] Specifically, it also includes a top plate 106, a drive plate 107, and an L-shaped mounting plate 108. The top plate 106 is disposed on the inner top wall of the hot-press bonding chamber. The six-degree-of-freedom piezoelectric ceramic actuator 101 is disposed on the lower end wall of the top plate 106. The drive plate 107 is fixedly connected to the output end of the six-degree-of-freedom piezoelectric ceramic actuator 101. The L-shaped mounting plates 108 are respectively disposed at both ends of the drive plate 107. The servo drive motor 102 is disposed on the L-shaped mounting plate 108. The flexible grippers 103 are all arranged in an arc shape, and the wafer is clamped and fixed by the flexible grippers.

[0044] Specifically, it also includes a flexible gripper fixing plate 109, which is fixedly connected to the output shaft of the servo drive motor 102. The flexible gripper 103 is fixedly connected to the flexible gripper fixing plate 109. Multiple limiting blocks 1031 are protruding from the lower end of the inner peripheral wall at both ends of the flexible gripper 103. The inner peripheral wall of the flexible gripper 103 can abut against the outer peripheral wall of the upper wafer 300, and the limiting blocks 1031 can abut against the lower end wall of the edge of the upper wafer 300. The wafer is clamped and fixed by the flexible gripper.

[0045] Specifically, it also includes a pressure roller arm 110, a pressure roller 111, and a push rod 112. The pressure roller arm 110 is vertically and vertically mounted on the outside of the flexible gripper 103. The pressure roller arm 110 is rotatably connected to the flexible gripper fixing plate 109. The pressure roller 111 is rotatably mounted on the lower end of the pressure roller arm 110. The push rod 112 is slidably mounted on the L-shaped mounting plate 108. The front end of the push rod 112 abuts against the pressure roller arm 110. The pressure roller 111 abuts against the upper wafer 300. Under the downward pressure of the pressure roller, the wafer can be effectively prevented from loosening.

[0046] Specifically, it also includes a support frame 113, a lifting cylinder 114, a U-shaped connector 115, and a pushing cylinder 116. The support frame 113 is set on the upper wall of the flexible gripper fixing plate 109. The lifting cylinder 114 is set on the upper end of the support frame 113. The pushing cylinder 116 is set on the L-shaped mounting plate 108. The U-shaped connector 115 is fixedly connected to the cylinder rod of the lifting cylinder 114. The upper end of the pressure roller arm 110 is rotatably connected to the U-shaped connector 115 through a short shaft. The cylinder rod of the pushing cylinder 116 is fixedly connected to the push rod 112. The push rod pushes the roller to the upper end of the wafer, and then the wafer is pressed under the gravity of the pressure roller, which can effectively prevent the wafer from loosening.

[0047] Specifically, the linewidth range of the translucent cross-shaped alignment mark 201 and the opaque cross-shaped alignment mark 301 is 0.1μm to 0.2μm. The translucent cross-shaped alignment mark is a positive cross, and the opaque cross-shaped alignment mark is a negative cross. When the positive and negative crosses are perfectly aligned, the CCD camera cannot detect the light from the light source, indicating that the upper and lower wafers are perfectly aligned. When there is an alignment deviation between the positive and negative crosses, the light from the light source will pass through the gap between the positive and negative crosses, allowing the CCD camera to detect the light from the light source. This indicates that there is an alignment deviation between the upper and lower wafers, and dynamic compensation and adjustment of the upper wafer position are required until the CCD camera can no longer detect the light from the light source.

[0048] Specifically, the wavelengths of the light source 105 include the visible light band and the infrared band.

[0049] Specifically, the light source 105 employs a dual-band spectrum, which can effectively improve the detection accuracy of the CCD camera, thereby effectively improving the alignment accuracy between the upper and lower wafers. The dual-band spectrum has the following advantages:

[0050] 1. Utilize the complementarity of dual spectra: combine the visible light (for low temperature / after cooling) and infrared (for high temperature) bands.

[0051] 2. Special marking design: High-temperature resistant materials are used, and their optical properties (emissivity / reflectivity) in two bands (especially the infrared band at high temperatures) are carefully designed to create high contrast with the background under their respective applicable temperature conditions.

[0052] 3. Dual-mode recognition: Relying on infrared imaging for recognition at high temperatures and visible light imaging for recognition after cooling, this ensures reliable acquisition of marker information throughout the entire temperature change process, effectively solving the problem of marker recognition degradation caused by high temperatures. This design significantly improves object recognition capabilities and automation levels in extreme thermal environments.

[0053] Specifically, the flexible gripper 103 is made of shape memory alloy material and can be adapted to hold and fix wafers of different sizes.

[0054] On the other hand, such as Figure 7 As shown, this invention also proposes a wafer dynamic alignment method using the above-mentioned hybrid bonding wafer dynamic alignment system based on multimodal sensors. The wafer dynamic alignment method includes the following steps:

[0055] S1: Place the lower wafer on the lower suction cup and fix it by adsorption through the vacuum suction hole;

[0056] [S2: The upper wafer is clamped and fixed by flexible grippers, and the upper wafer is aligned and fixed above the lower wafer to complete the coarse alignment of the upper and lower wafers. The upper wafer is pressed and adhered to the lower wafer by the upper suction cup. The thermo-bonding chamber is heated to the target temperature at a rate of 10℃ / s. Pressure is applied to the upper wafer through a three-stage pressurization method.]

[0057] S3: Real-time data acquisition. The infrared thermal imager is used to measure the local temperature of the upper wafer to obtain an infrared thermal image. The local thermal expansion coefficient of the upper wafer is calculated based on the infrared thermal image. The expansion amount of the upper wafer in the X and Y directions is measured by a laser differential interferometer. The pressure between the upper and lower wafers is measured by a piezoelectric pressure sensor. The acquired data is then uploaded to the compensation controller.

[0058] S4: The compensation amounts Δx and Δy in the X and Y directions are calculated using the built-in algorithm of the compensation controller and output to the six-degree-of-freedom piezoelectric ceramic actuator;

[0059] S5: The six-degree-of-freedom piezoelectric ceramic actuator dynamically compensates for the position of the upper wafer based on the values ​​of the compensation amounts Δx and Δy.

[0060] S6: Verify the alignment accuracy between the upper and lower wafers using a CCD camera and a light source. When the CCD camera detects light from the light source, it indicates that there is an offset in the alignment between the upper and lower wafers. Repeat steps S3 to S6 until the CCD camera can no longer detect light from the light source. Then, the precise alignment between the upper and lower wafers is completed, and hot-press bonding begins.

[0061] Specifically, taking silicon-glass thermocompression bonding as an example, the wafer dynamic compensation process is explained. The upper wafer material is a glass substrate with a local thermal expansion coefficient α of 8.5 × 10⁻⁶, a pressure deformation coefficient kx in the X direction of the wafer of 0.12 nm / MPa, a bonding temperature T of 350℃, a bonding pressure P of 80 MPa (loaded in 3 segments), a wafer diameter L of 300 mm, a room temperature T0 = 25℃, and a room pressure P0 = 0 MPa. The specific compensation process is as follows:

[0062] When the CCD camera detects light from the light source, it indicates that there is an alignment deviation between the upper and lower wafers. Dynamic compensation and adjustment of the upper wafer's position are required. The compensation process is as follows: First, the compensation amount is calculated:

[0063] ΔX=α·L·(T-T0)+kx·(P-P0)=(8.5×10-6)×300mm×(350-25)+0.12nm / MPa×(80-0)=0.83μm+9.6nm≈0.84μm

[0064] A six-degree-of-freedom piezoelectric ceramic actuator compensates for a displacement of -0.84 μm in the X direction;

[0065] Continue to verify the alignment accuracy between the upper and lower wafers using a CCD camera and a light source. If the CCD camera detects light from the light source, continue to compensate until the CCD camera can no longer detect light from the light source.

[0066] Specifically, the technical solution of the present invention can achieve real-time dynamic alignment of wafers under high temperature and high pressure (accuracy ±0.5μm), suppress bonding offset caused by thermal expansion differences, perform nanometer-level position correction on wafers, solve the problem of wafer alignment mark recognition degradation under high temperature conditions, greatly improve wafer alignment accuracy, and achieve high-precision dynamic alignment between chip wafers and substrate wafers in thermo-press bonding processes, meeting the ±0.5μm level alignment accuracy requirements of 3DIC integration and Chiplet heterogeneous packaging.

[0067] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A hybrid bonding wafer dynamic alignment system based on a multimodal sensor, used for thermo-press bonding of a lower wafer and an upper wafer, characterized in that, The system includes a thermocompression bonding chamber, a six-degree-of-freedom piezoelectric ceramic actuator, a servo drive motor, flexible grippers, a CCD camera, a light source, an infrared thermal imager, a piezoelectric pressure sensor, a laser differential interferometer, a clamping force detection sensor, and a compensation controller. The lower wafer is adsorbed and fixed to the bottom of the thermocompression bonding chamber by a lower suction cup. The six-degree-of-freedom piezoelectric ceramic actuator is disposed on the inner top wall of the thermocompression bonding chamber. The flexible grippers are respectively disposed on both sides above the lower suction cup. The servo drive motor is connected to the output end of the six-degree-of-freedom piezoelectric ceramic actuator. The flexible gripper is fixedly connected to the output shaft of the servo drive motor. The flexible gripper is used to hold and fix the upper wafer. The six-degree-of-freedom piezoelectric ceramic actuator is used to compensate and adjust the position of the upper wafer to ensure precise alignment with the lower wafer. The CCD cameras are respectively positioned on both sides above the upper wafer, and the light sources are respectively positioned on both sides below the lower wafer. A translucent cross-shaped alignment mark is provided on both sides of the upper end wall of the lower wafer, and an opaque cross-shaped alignment mark corresponding to the translucent cross-shaped alignment mark is provided on both sides of the upper end wall of the upper wafer. The light source position... Directly below the translucent cross-shaped alignment mark, the CCD camera is positioned directly above the opaque cross-shaped alignment mark. The CCD camera and light source are used to verify whether the upper and lower wafers are aligned. The infrared thermal imager, piezoelectric pressure sensor, and compensation controller are disposed within the thermo-bonding chamber. The infrared thermal imager is used to measure the local temperature of the upper and lower wafers, and the piezoelectric pressure sensor is used to measure the pressure applied between the upper and lower wafers. The laser differential interferometer and clamping force detection sensor are disposed within the servo drive. Inside the motor, the laser differential interferometer is used to measure the expansion of the upper wafer in the X and Y directions, and the clamping force detection sensor is used to detect the clamping force of the flexible gripper. The compensation controller is electrically connected to the six-degree-of-freedom piezoelectric ceramic actuator, CCD camera, infrared thermal imager, piezoelectric pressure sensor, servo drive motor, laser differential interferometer, and clamping force detection sensor. The compensation controller calculates the compensation amount Δx in the X direction and the compensation amount Δy in the Y direction of the upper wafer and outputs it to the six-degree-of-freedom piezoelectric ceramic actuator for dynamic compensation.

2. The hybrid bonding wafer dynamic alignment system based on multimodal sensors according to claim 1, characterized in that, The Δx and Δy mentioned above are calculated using the following formulas: Δx=α·L·(T-T0)+kx·(P-P0) Δy=α·L·(T-T0)+ky·(P-P0) Where α is the local thermal expansion coefficient of the wafer, determined according to the wafer material, L is the diameter of the wafer, kx and ky are the pressure deformation coefficients of the wafer in the X and Y directions, respectively, determined according to the elastic modulus of the wafer material, T is the local temperature of the wafer, T0 is the initial temperature of the wafer, T0 = 25℃, P is the local pressure of the wafer, P0 is the initial pressure of the wafer, P0 = 0MPa.

3. The hybrid bonding wafer dynamic alignment system based on multimodal sensors according to claim 1, characterized in that, It also includes a top plate, a drive plate, and an L-shaped mounting plate. The top plate is disposed on the inner top wall of the hot-press bonding chamber. The six-degree-of-freedom piezoelectric ceramic actuator is disposed on the lower end wall of the top plate. The drive plate is fixedly connected to the output end of the six-degree-of-freedom piezoelectric ceramic actuator. The L-shaped mounting plates are respectively disposed at both ends of the drive plate. The servo drive motor is disposed on the L-shaped mounting plate. The flexible grippers are all arranged in an arc shape.

4. The hybrid bonding wafer dynamic alignment system based on multimodal sensors according to claim 3, characterized in that, It also includes a flexible gripper fixing plate, which is fixedly connected to the output shaft of the servo drive motor. The flexible gripper is fixedly connected to the flexible gripper fixing plate. Multiple limiting blocks are protruding from the lower end of the inner peripheral wall at both ends of the flexible gripper. The inner peripheral wall of the flexible gripper can abut against the outer peripheral wall of the upper wafer, and the limiting blocks can abut against the lower end wall of the edge of the upper wafer.

5. The hybrid bonding wafer dynamic alignment system based on a multimodal sensor according to claim 4, characterized in that, It also includes a pressure roller arm, a pressure roller, and a push rod. The pressure roller arm is vertically movable and is disposed on the outside of the flexible gripper. The pressure roller arm is rotatably connected to the flexible gripper fixing plate. The pressure roller is rotatably disposed on the lower end of the pressure roller arm. The push rod is slidably disposed on the L-shaped mounting plate. The front end of the push rod abuts against the pressure roller arm. The pressure roller can abut against the upper wafer.

6. The hybrid bonding wafer dynamic alignment system based on a multimodal sensor according to claim 5, characterized in that, It also includes a support frame, a lifting cylinder, a U-shaped connector, and a pushing cylinder. The support frame is disposed on the upper wall of the flexible gripper fixing plate, the lifting cylinder is disposed on the upper end of the support frame, the pushing cylinder is disposed on the L-shaped mounting plate, the U-shaped connector is fixedly connected to the cylinder rod of the lifting cylinder, the upper end of the pressure roller arm is rotatably connected to the U-shaped connector through a short shaft, and the cylinder rod of the pushing cylinder is fixedly connected to the push rod.

7. The hybrid bonding wafer dynamic alignment system based on multimodal sensors according to claim 1, characterized in that, The line width of the translucent cross-shaped alignment mark and the opaque cross-shaped alignment mark ranges from 0.1 μm to 0.2 μm.

8. The hybrid bonding wafer dynamic alignment system based on multimodal sensors according to claim 1, characterized in that, The light source has wavelengths including the visible light band and the infrared band.

9. The hybrid bonding wafer dynamic alignment system based on multimodal sensors according to claim 1, characterized in that, The flexible gripper is made of shape memory alloy.

10. A wafer dynamic alignment method for a hybrid bonding wafer dynamic alignment system based on a multimodal sensor according to any one of claims 1 to 9, characterized in that, The wafer dynamic alignment method includes the following steps: S1: Place the lower wafer on the lower suction cup and fix it by adsorption through the vacuum suction hole; S2: The upper wafer is clamped and fixed by flexible grippers, and the upper wafer is aligned and fixed above the lower wafer to complete the coarse alignment of the upper and lower wafers. The upper wafer is pressed and adhered to the lower wafer by the upper suction cup. The thermo-bonding chamber is heated to the target temperature at a rate of 10℃ / s. Pressure is applied to the upper wafer through a three-stage pressurization method. S3: Real-time data acquisition. The infrared thermal imager is used to measure the local temperature of the upper wafer to obtain an infrared thermal image. The local thermal expansion coefficient of the upper wafer is calculated based on the infrared thermal image. The expansion amount of the upper wafer in the X and Y directions is measured by a laser differential interferometer. The pressure between the upper and lower wafers is measured by a piezoelectric pressure sensor. The acquired data is then uploaded to the compensation controller. S4: The compensation amounts Δx and Δy in the X and Y directions are calculated using the built-in algorithm of the compensation controller and output to the six-degree-of-freedom piezoelectric ceramic actuator; S5: The six-degree-of-freedom piezoelectric ceramic actuator dynamically compensates for the position of the upper wafer based on the values ​​of the compensation amounts Δx and Δy. S6: Verify the alignment accuracy between the upper and lower wafers using a CCD camera and a light source. When the CCD camera detects light from the light source, it indicates that there is an offset in the alignment between the upper and lower wafers. Repeat steps S3 to S6 until the CCD camera can no longer detect light from the light source. Then, the precise alignment between the upper and lower wafers is completed, and hot-press bonding begins.

Images