Wafer backside contact type positioning and clamping fixing device and wafer bonding method

Abstract

The application discloses a wafer back contact type positioning and clamping fixing device and a wafer bonding method, and belongs to the technical field of wafer bonding. The wafer back contact type positioning and clamping fixing device comprises a bonding chamber, a lower suction disc, an upper pressing disc, a controller, a pressing driving mechanism, a positioning pressing rod, a clamping driving mechanism and flexible clamping paws. The lower end of the positioning pressing rod is in abutment with the upper end wall of the lower suction disc. The clamping driving mechanism is arranged on the two sides of the lower suction disc in a sliding mode. The flexible clamping paws are connected with the clamping driving mechanism. The flexible clamping paws are driven to slide along the radial direction of the lower suction disc by the clamping driving mechanism. The flexible clamping paws are used for clamping and fixing wafers. The inner circumferential wall of the flexible clamping paws is in abutment with the outer circumferential wall of the wafer. The limiting block is in abutment with the lower end wall of the edge of the wafer. The pressing driving mechanism and the clamping driving mechanism are electrically connected with the controller. The technical scheme of the application can avoid wafer surface pollution and damage, effectively improve the stability of the wafer bonding process, reduce the waste rate, save the cost, and has high market application and popularization value.

Description

Technical Field

[0001] This invention relates to the field of bonding equipment technology, and in particular to a wafer back-side contact positioning and clamping device and a wafer bonding method. Background Technology

[0002] In semiconductor manufacturing, bonding is a back-end packaging process. Wafer bonding is the process of tightly joining two or more wafers together using physical or chemical methods. It is used for various purposes, such as enabling chip interconnection, reducing package size, improving wafer structural strength, and preventing wafer deformation during subsequent processing. It is divided into wafer-to-wafer (W2W) bonding and die-to-wafer (D2W) bonding. W2W primarily refers to the direct bonding of two clean, atomically flat, homogeneous or heterogeneous semiconductor materials under certain conditions after surface cleaning and activation treatment. Van der Waals forces, molecular forces, and even atomic forces are used to integrate the two semiconductor materials. W2W refers to the process of permanently bonding wafers to wafers, wafers to glass substrates, or other material wafers through chemical or physical reactions. The bonding process involves atoms at the interface of two wafers reacting to form covalent bonds under the influence of external energy, thus bonding the wafers and achieving a certain interface bonding strength. D2W refers to attaching the chips cut from the wafers to the packaging substrate (lead frame or printed circuit board) after the dicing process. Chip bonding processes can be divided into traditional and advanced methods. Traditional methods use die bonding and wire bonding, while advanced methods use flip chip bonding, hybrid bonding, and other technologies. From the perspective of bonding methods, wafer bonding can be divided into permanent bonding and temporary bonding. The difference is self-explanatory: permanent bonding does not require debonding, while temporary bonding requires debonding to reopen the bonded wafers. From the perspective of interface materials, it includes adhesive bonding with an interlayer, eutectic bonding, metal thermocompression bonding, fusion bonding without an interlayer, and anodic bonding.

[0003] In the wafer bonding process, precise wafer positioning and fixation are crucial and directly affect the quality of chip stacking and packaging. Currently, traditional bonding equipment mainly uses electrostatic chucks (ESCs) to attract wafers through an electrostatic field to achieve precise wafer positioning and fixation. However, ESCs have a complex structure and extremely high manufacturing costs, typically exceeding one million dollars, which significantly increases the production costs for enterprises.

[0004] While existing mechanical clamping solutions are low-cost, they are prone to causing wafer edge damage or contamination. Most importantly, they cannot achieve precise wafer positioning and prevent wafer misalignment. Therefore, there is an urgent need for a low-cost, highly reliable wafer positioning and clamping device that can adapt to multi-physics coupling environments. Summary of the Invention

[0005] The main objective of this invention is to provide a wafer back-side contact positioning and clamping device and a wafer bonding method, which aims to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention proposes a wafer back-side contact positioning and clamping device, comprising a bonding chamber, a lower suction cup, an upper pressure plate, a controller, a clamping drive mechanism, a positioning rod, a clamping drive mechanism, and flexible grippers. The lower suction cup is disposed at the lower end of the bonding chamber, and the upper pressure plate is slidably disposed at the upper end of the bonding chamber, with the lower end wall of the upper pressure plate abutting against the upper end wall of the lower suction cup. The outer periphery of the upper end face of the lower suction cup is provided with multiple vacuum suction holes, which are connected to a vacuum pump. The lower suction cup is used to fix the lower wafer. The controller is disposed within the bonding chamber, and the clamping drive mechanism is disposed at the upper end of the bonding chamber. A through hole is recessed at the center point of the upper end of the upper pressure plate, through which the positioning rod slidably passes. The clamping drive mechanism is fixedly connected to the upper end of the positioning rod, driving the positioning rod to slide up and down. The lower end of the positioning pressure rod can abut against the upper end wall of the lower suction cup. The clamping drive mechanism is slidably arranged on both sides of the lower suction cup. The clamping drive mechanism is symmetrically arranged from left to right. The outer contour of the flexible claw is arc-shaped. Multiple limiting blocks are protruding from the lower end of the inner peripheral wall at both ends of the flexible claw. The flexible claw is connected to the clamping drive mechanism. The clamping drive mechanism drives the flexible claw to slide along the radial direction of the lower suction cup. The flexible claw is used to clamp and fix the wafer. The inner peripheral wall of the flexible claw can abut against the outer peripheral wall of the wafer. The limiting block can abut against the lower end wall of the edge of the wafer. The pressing drive mechanism and the clamping drive mechanism are electrically connected to the controller. The controller has a PID algorithm. The controller controls the action of the pressing drive mechanism and the clamping drive mechanism, thereby controlling the downward pressure of the positioning pressure rod and the clamping force of the flexible claw.

[0007] Optionally, the system further includes a linear module, a mounting plate, and a flexible gripper fixing plate. The linear module is vertically disposed on both sides of the lower suction cup. The mounting plate is fixedly connected to the slider of the linear module. The clamping drive mechanism is disposed on the mounting plate and is a servo drive motor. The middle of the flexible gripper is fixedly connected to the output shaft of the servo drive motor. The linear module is electrically connected to the controller. The flexible gripper fixing plate is fixedly connected to the output shaft of the servo drive motor, and the flexible gripper is fixedly connected to the flexible gripper fixing plate.

[0008] Optionally, it also includes a clamping force detection sensor, which is respectively disposed inside the servo drive motor. The clamping force detection sensor is connected to the push rod of the servo drive motor and electrically connected to the controller. The clamping force detection sensor is used to detect the clamping force of the flexible gripper.

[0009] Optionally, a laser displacement sensor is also included. The laser displacement sensor is disposed inside the servo drive motor and is electrically connected to the controller. The laser displacement sensor is used to detect the position of the flexible gripper.

[0010] Optionally, the pressing drive mechanism is a cylinder, and the cylinder rod of the cylinder is fixedly connected to the upper end of the positioning pressure rod.

[0011] Optionally, the two side walls of the lower suction cup are provided with a plurality of clearance grooves corresponding one-to-one with the limiting block, and the limiting block can be embedded in the clearance groove.

[0012] Optionally, the flexible gripper is formed of a shape memory alloy.

[0013] 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 at the lower end of the pressure roller arm. The push rod is slidably disposed on the mounting plate. The front end of the push rod abuts against the pressure roller arm. The pressure roller can abut against the upper wafer.

[0014] Optionally, it also includes an L-shaped bracket, a lifting cylinder, a U-shaped connector, and a pushing cylinder. The L-shaped bracket is disposed on the upper wall of the flexible gripper fixing plate, the lifting cylinder is disposed on the upper end of the L-shaped bracket, the pushing cylinder is disposed on the 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.

[0015] On the other hand, the present invention also proposes a wafer bonding method using the above-mentioned wafer back-side contact positioning and clamping device, comprising the following steps:

[0016] The lower wafer to be bonded is fed into the bonding chamber with its front facing upward by a robotic arm. The flexible grippers are driven by a clamping drive mechanism to clamp and fix the lower wafer from the left and right. The clamping force detection sensor ensures that the clamping force of the flexible grippers on both sides is consistent. After aligning the flexible grippers with the lower suction cup, the flexible grippers are driven to descend by a linear module to place the lower wafer on the lower suction cup. The vacuum suction hole of the lower suction cup forms a negative pressure, thereby fixing the lower wafer on the lower suction cup.

[0017] The upper wafer to be bonded is fed into the bonding chamber with its back side facing up by a robotic arm. The flexible grippers are driven by a clamping drive mechanism to clamp and fix the upper wafer on the left and right. The clamping force detection sensor ensures that the clamping force of the flexible grippers on both sides is consistent, so that the upper wafer is aligned with the lower wafer. The flexible grippers are then driven by a linear module to descend and suspend the upper wafer at a distance of 100um to 150um from the lower wafer.

[0018] The positioning rod is pressed down by the clamping drive mechanism, so that the positioning rod abuts against the center point of the upper wafer, thereby making the center point of the upper wafer fit with the center point of the lower wafer, ensuring that the upper and lower wafers will not be misaligned;

[0019] The upper pressure plate is driven to descend, bringing it into contact with the upper wafer and pressing it firmly onto the lower wafer, thereby achieving bonding between the upper and lower wafers.

[0020] The technical solution of this invention has the following beneficial effects: The positioning pressure bar, through its synergistic action with the flexible gripper, achieves non-destructive wafer fixation and dynamic position compensation, effectively ensuring that the upper and lower wafers do not shift after alignment. Furthermore, it ensures that air between the upper and lower wafers is expelled from the center towards the edge, reducing air residue in the center during wafer bonding and effectively improving the quality of wafer bonding. The flexible gripper, while clamping the wafer, can dynamically and precisely adjust the clamping force through a controller and clamping force detection sensor, monitoring the clamping force in real time. This ensures accurate wafer alignment while preventing damage to the wafer due to excessive clamping force. The controller precisely controls the downward pressure of the positioning pressure bar to avoid damaging the wafer. The flexible gripper of this invention is a non-face-contact fixation method, avoiding wafer surface contamination and damage. It is suitable for processes with high cleanliness requirements, effectively improving the stability of the wafer bonding process, reducing scrap rates, and significantly saving costs, thus possessing high market application and promotion value. Attached Figure Description

[0021] 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.

[0022] Figure 1 This is a partial structural schematic diagram of a wafer back-side contact positioning and clamping device according to an embodiment of the present invention.

[0023] Figure 2 This is a partially exploded structural diagram of a wafer backside contact positioning and clamping device according to an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of another part of the structure of a wafer back-side contact positioning and clamping device according to an embodiment of the present invention;

[0025] Figure 4 This is a flowchart illustrating the steps of a wafer bonding method using a wafer backside contact positioning and clamping device according to an embodiment of the present invention.

[0026] 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

[0027] 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.

[0028] 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.

[0029] 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.

[0030] This invention proposes a wafer back-side contact positioning and clamping device and a wafer bonding method.

[0031] like Figures 1 to 3 As shown, in one embodiment of the present invention, the wafer back-side contact positioning and clamping device includes a bonding chamber (not shown), a lower suction cup 101, an upper pressure plate 102, a controller (not shown), a clamping drive mechanism (not shown), a positioning pressure rod 103, a clamping drive mechanism 104, and flexible grippers 105. The lower suction cup 101 is disposed at the lower end of the bonding chamber, and the upper pressure plate 102 is slidably disposed at the upper end of the bonding chamber. The lower end wall of the upper pressure plate 102 can abut against the upper end wall of the lower suction cup 101. The outer periphery of the upper end surface of the lower suction cup 101 is provided with multiple... A vacuum suction port (not shown) is connected to a vacuum pump. The lower suction cup is used to fix the lower wafer. The lower suction cup 101 is used for aligning the upper and lower wafers before the bonding chamber is evacuated. After the upper and lower wafers are aligned, the vacuum of the lower suction cup 101 is turned off. The bonding chamber is evacuated by a molecular pump vacuum generator. The controller is located in the bonding chamber. The clamping drive mechanism is located at the upper end of the bonding chamber. A through hole (not shown) is recessed at the center point of the upper end of the upper pressure plate 102. The positioning pressure rod 103 can slide up and down through the through hole. The mechanism is fixedly connected to the upper end of the positioning rod 103. The positioning rod 103 is driven to slide up and down by the clamping drive mechanism. The lower end of the positioning rod 103 can abut against the upper end wall of the lower suction cup 101. The clamping drive mechanism 104 is slidably arranged on both sides of the lower suction cup 101. The clamping drive mechanism 104 is symmetrically arranged from left to right. The outer contour of the flexible gripper 105 is arc-shaped. Multiple limiting blocks 1051 protrude from the lower end of the inner peripheral wall at both ends of the flexible gripper 105. The flexible gripper 105 is connected to the clamping drive mechanism 104. The driving mechanism 104 drives the flexible grippers 105 to slide along the radial direction of the lower suction cup 101. The flexible grippers 105 are used to clamp and fix the wafer. The inner peripheral wall of the flexible grippers 105 can abut against the outer peripheral wall of the wafer. The limiting block 1051 can abut against the lower end wall of the edge of the wafer. The pressing drive mechanism and the clamping drive mechanism 104 are electrically connected to the controller. The controller is equipped with a PID algorithm. The controller controls the action of the pressing drive mechanism and the clamping drive mechanism 104, thereby controlling the downward pressure of the positioning pressure rod 103 and the clamping force of the flexible grippers 105.

[0032] Specifically, the lower suction cup 101 is used for aligning the upper and lower wafers before the bonding chamber is evacuated. After the upper and lower wafers are aligned, the vacuum of the lower suction cup 101 is turned off, and the bonding chamber is evacuated by a molecular pump vacuum generator, which facilitates wafer bonding.

[0033] Specifically, it also includes a linear module (not shown), a mounting plate 106, and a flexible gripper fixing plate 107. The linear module is vertically arranged on both sides of the lower suction cup 101. The mounting plate 106 is fixedly connected to the slider of the linear module. The clamping drive mechanism 104 is arranged on the mounting plate 106. The clamping drive mechanism 104 is a servo drive motor. The middle of the flexible gripper 105 is fixedly connected to the output shaft of the servo drive motor. The linear module is electrically connected to the controller. The flexible gripper fixing plate 107 is fixedly connected to the output shaft of the servo drive motor. The flexible gripper 105 is fixedly connected to the flexible gripper fixing plate 107. The flexible gripper is driven to move up and down by the linear module to achieve wafer bonding.

[0034] Specifically, it also includes a clamping force detection sensor (not shown). The clamping force detection sensor is located inside the servo drive motor and is connected to the push rod of the servo drive motor. The clamping force detection sensor is electrically connected to the controller. The clamping force detection sensor is used to detect the clamping force of the flexible gripper and monitor the clamping force in real time. While ensuring accurate alignment, it avoids damage to the wafer due to excessive clamping force.

[0035] Specifically, it also includes a laser displacement sensor (not shown), which is located inside the servo drive motor and is electrically connected to the controller. The laser displacement sensor is used to detect the position of the flexible gripper, thereby facilitating precise wafer alignment.

[0036] Specifically, the clamping drive mechanism is a cylinder, and the cylinder rod is fixedly connected to the upper end of the positioning pressure rod 103. The downward pressure of the cylinder is precisely controlled to avoid damaging the wafer.

[0037] Specifically, the lower suction cup 101 has multiple recessed clearance grooves 1011 on both sides, which correspond one-to-one with the limiting block 1051. The limiting block 1051 can be embedded in the clearance groove 1011.

[0038] Specifically, the flexible gripper 105 is made of shape memory alloy. Shape memory alloy is a material composed of two or more metallic elements that has a shape memory effect through thermoelastic and martensitic phase transformation and its inversion. Shape memory alloy can flexibly change shape, thereby flexibly adapting to the clamping and fixing of wafers of various sizes and models. This makes the flexible gripper more adaptable and at the same time provides good protection for the wafer, effectively avoiding damage to the wafer.

[0039] Specifically, such as Figure 3As shown, it also includes a pressure roller arm 108, a pressure roller 109, and a push rod 110. The pressure roller arm 108 is vertically movable and is located on the outside of the flexible gripper 105. The pressure roller arm 108 is rotatably connected to the flexible gripper fixing plate 107. The pressure roller 109 is rotatably located at the lower end of the pressure roller arm 108. The push rod 110 is slidably located on the mounting plate 106. The front end of the push rod 110 abuts against the pressure roller arm 108. The pressure roller 109 can abut against the upper wafer 300. When the wafer is aligned, the pressure roller can be pushed to the upper end of the wafer and the wafer can be pressed under the gravity of the pressure roller, which can effectively prevent the wafer from loosening and affecting the bonding alignment accuracy.

[0040] Specifically, such as Figure 3 As shown, it also includes an L-shaped bracket 111, a lifting cylinder 112, a U-shaped connector 113, and a pushing cylinder 114. The L-shaped bracket 111 is set on the upper wall of the flexible gripper fixing plate 107. The lifting cylinder 112 is set on the upper end of the L-shaped bracket 111. The pushing cylinder 114 is set on the mounting plate 106. The U-shaped connector 113 is fixedly connected to the cylinder rod of the lifting cylinder 112. The upper end of the pressure roller arm 108 is rotatably connected to the U-shaped connector 113 through a short shaft. The cylinder rod of the pushing cylinder 114 is fixedly connected to the push rod 110. When the wafer is aligned, the lifting cylinder raises the pressure roller. Then, under the action of the push rod cylinder, the push rod is driven to move forward. The push rod pushes the roller to the upper end of the wafer. Then, under the gravity of the pressure roller, the wafer is pressed, which can effectively prevent the wafer from loosening.

[0041] On the other hand, such as Figure 4 As shown, the present invention also proposes a wafer bonding method using the above-mentioned wafer back-side contact positioning and clamping device, comprising the following steps:

[0042] S100: The lower wafer to be bonded is fed into the bonding chamber with its front facing up by a robotic arm, and the flexible grippers are driven by a clamping drive mechanism to clamp and fix the lower wafer from the left and right. The clamping force detection sensor makes the clamping force of the flexible grippers on both sides equal, so that it is aligned with the lower suction cup. The flexible grippers are driven to descend by a linear module to place the lower wafer on the lower suction cup. The vacuum suction hole of the lower suction cup forms a negative pressure, thereby fixing the lower wafer on the lower suction cup.

[0043] S200: The upper wafer to be bonded is fed into the bonding chamber with its back side facing up by a robotic arm, and the flexible grippers are driven by a clamping drive mechanism to clamp and fix the upper wafer on the left and right. The clamping force detection sensor makes the clamping force of the flexible grippers on both sides consistent, so that it is aligned with the lower wafer. Then, the flexible grippers are driven by a linear module to descend and suspend the upper wafer at a position 100um~150um away from the lower wafer.

[0044] S300: The positioning rod is driven to press down by the clamping drive mechanism, so that the positioning rod abuts against the center point of the upper wafer, thereby making the center point of the upper wafer fit with the center point of the lower wafer, ensuring that the upper and lower wafers will not be misaligned;

[0045] S400: Drives the upper pressure plate to descend, bringing it into contact with the upper wafer and pressing it firmly onto the lower wafer, thereby achieving bonding between the upper and lower wafers.

[0046] Specifically, the technical solution of this invention achieves non-destructive wafer fixation and dynamic position compensation through the synergistic action of the positioning pressure bar and the flexible gripper. This effectively ensures that the upper and lower wafers do not shift after alignment, and ensures that air between the upper and lower wafers is discharged from the center to the edge during the bonding process. This reduces air residue in the center during wafer bonding and effectively improves the quality of wafer bonding. When clamping the wafer, the flexible gripper can dynamically and accurately adjust the clamping force through a controller and clamping force detection sensor, and monitor the clamping force in real time. This ensures accurate alignment while avoiding damage to the wafer due to excessive clamping force. The controller precisely controls the downward pressure of the positioning pressure bar to avoid damaging the wafer. The flexible gripper of this invention is a non-face-contact fixation method, avoiding contamination and damage to the wafer surface. It is suitable for processes with high cleanliness requirements, effectively improves the stability of the wafer bonding process, reduces the scrap rate, and greatly saves costs, thus having high market application and promotion value.

[0047] 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 wafer backside contact type positioning and chucking fixture, characterized by, The utility model provides a wafer bonding device, which comprises a bonding chamber, a lower chuck, an upper pressing plate, a controller, a pressing driving mechanism, a positioning pressing rod, a clamping driving mechanism and flexible clamping jaws, the lower chuck is arranged at the lower end of the bonding chamber, the upper pressing plate is arranged at the upper end of the bonding chamber in a sliding manner, and the lower end wall of the upper pressing plate can abut against the upper end wall of the lower chuck, a plurality of vacuum suction holes are arranged on the outer periphery of the upper end surface of the lower chuck, the vacuum suction holes are communicated with a vacuum pump, the lower chuck is used for fixing a lower wafer, the controller is arranged in the bonding chamber, the pressing driving mechanism is arranged at the upper end of the bonding chamber, a through hole is arranged at the center point of the upper end of the upper pressing plate, the positioning pressing rod is arranged in the through hole in a sliding manner, the pressing driving mechanism is fixedly connected with the upper end of the positioning pressing rod, the positioning pressing rod is driven to slide up and down by the pressing driving mechanism, the lower end of the positioning pressing rod can abut against the upper end wall of the lower chuck, the clamping driving mechanism is arranged on the two sides of the lower chuck in a sliding manner, the clamping driving mechanism is arranged in a left-right symmetrical manner, the outer contour of the flexible clamping jaws is arranged in an arc-shaped structure, a plurality of limiting blocks are arranged on the inner peripheral wall of the two ends of the flexible clamping jaws, the flexible clamping jaws are connected with the clamping driving mechanism, the flexible clamping jaws are driven to slide along the radial direction of the lower chuck by the clamping driving mechanism, the flexible clamping jaws are used for clamping and fixing wafers, the inner peripheral wall of the flexible clamping jaws can abut against the outer peripheral wall of the wafer, the limiting blocks can abut against the lower end wall of the edge of the wafer, the pressing driving mechanism and the clamping driving mechanism are electrically connected with the controller, the controller is provided with a PID algorithm, the pressing driving mechanism and the clamping driving mechanism are controlled to act by the controller, so that the pressing force of the positioning pressing rod and the clamping force of the flexible clamping jaws are controlled.

2. The backside contact wafer positioning and chucking fixture of claim 1, wherein, The utility model also comprises a linear module, a mounting plate and a flexible clamping jaw fixing plate, the linear module is vertically arranged on the two sides of the lower chuck, the mounting plate is fixedly connected with the sliding block of the linear module, the clamping driving mechanism is arranged on the mounting plate, the clamping driving mechanism is a servo driving motor, the middle of the flexible clamping jaws is fixedly connected with the output shaft of the servo driving motor, the linear module is electrically connected with the controller, the flexible clamping jaw fixing plate is fixedly connected with the output shaft of the servo driving motor, and the flexible clamping jaws are fixedly connected with the flexible clamping jaw fixing plate.

3. The backside contact wafer positioning and chucking fixture of claim 2, wherein, The utility model also comprises a clamping force detection sensor, the clamping force detection sensor is arranged in the servo driving motor, the push rod of the servo driving motor is connected with the clamping force detection sensor, the clamping force detection sensor is electrically connected with the controller, and the clamping force detection sensor is used for detecting the clamping force of the flexible clamping jaws.

4. The backside contact wafer positioning and chucking fixture of claim 2, wherein, The utility model also comprises a laser displacement sensor, the laser displacement sensor is arranged in the servo driving motor, the laser displacement sensor is electrically connected with the controller, and the laser displacement sensor is used for detecting the position of the flexible clamping jaws.

5. The backside contact wafer positioning and chucking fixture of claim 1, wherein, The pressing driving mechanism is a cylinder, and a cylinder rod of the cylinder is fixedly connected with the upper end of the positioning pressing rod.

6. The backside contact wafer positioning and chucking fixture of claim 1, wherein, The two side walls of the lower suction disc are concavely provided with a plurality of avoidance grooves corresponding to the limiting blocks one by one, and the limiting blocks can be embedded in the avoidance grooves.

7. The backside contact wafer positioning and chucking fixture of claim 1, wherein, The flexible clamping jaw is formed of a shape memory alloy.

8. The backside contact wafer positioning and chucking fixture of claim 2, wherein, The device further comprises a pressing wheel arm, a pressing wheel and a push rod, the pressing wheel arm is arranged on the outside of the flexible clamping jaw and can be lifted up and down, the pressing wheel arm is rotationally connected with the flexible clamping jaw fixing plate, the pressing wheel is rotationally arranged on the lower end of the pressing wheel arm, the push rod is arranged on the mounting plate and can slide forward and backward, the front end of the push rod abuts against the pressing wheel arm, and the pressing wheel can abut against the upper wafer.

9. The backside contact wafer positioning and chucking fixture of claim 8, wherein, The device further comprises an L-shaped support, a lifting cylinder, a U-shaped connector and a pushing cylinder, the L-shaped support is arranged on the upper end wall of the flexible clamping jaw fixing plate, the lifting cylinder is arranged on the upper end of the L-shaped support, the pushing cylinder is arranged on the mounting plate, the U-shaped connector is fixedly connected with the cylinder rod of the lifting cylinder, the upper end of the pressing wheel arm is rotationally connected with the U-shaped connector through a short shaft, and the cylinder rod of the pushing cylinder is fixedly connected with the push rod.

10. A wafer bonding method using the wafer backside contact type positioning and chucking fixture according to any one of claims 1 to 9, characterized by, The wafer bonding method comprises the following steps: a lower wafer to be bonded is sent into a bonding chamber by a mechanical hand with the front face upward, flexible clamping jaws are driven by a clamping driving mechanism to clampingly fix the lower wafer left and right, the clamping force of the flexible clamping jaws on both sides is made uniform by a clamping force detection sensor, the lower wafer is centered with the lower suction disc, the flexible clamping jaws are driven downward by a linear module, the lower wafer is placed on the lower suction disc, a negative pressure is formed by vacuum suction holes of the lower suction disc, so that the lower wafer is fixed on the lower suction disc; an upper wafer to be bonded is sent into the bonding chamber by the mechanical hand with the back face upward, the flexible clamping jaws are driven by the clamping driving mechanism to clampingly fix the upper wafer left and right, the clamping force of the flexible clamping jaws on both sides is made uniform by the clamping force detection sensor, the upper wafer is centered with the lower wafer, the flexible clamping jaws are driven downward by the linear module, and the upper wafer is suspended at a position 100um-150um away from the lower wafer; the positioning pressing rod is driven downward by a pressing driving mechanism, so that the positioning pressing rod abuts against the center point of the upper wafer, the center point of the upper wafer is bonded with the center point of the lower wafer, and the upper and lower wafers are prevented from being misaligned; the upper pressing disc is driven to descend, so that the upper pressing disc abuts against the upper wafer and the upper wafer is pressed on the lower wafer, thereby realizing the bonding of the upper and lower wafers.

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