Wafer self-adaptive grabbing system and method based on dynamic force feedback

Abstract

The invention discloses a wafer self-adaptive grabbing system and method based on dynamic force feedback, and belongs to the technical field of semiconductor material processing and carrying. According to the system, an edge-lower support fusion type clamping jaw structure is adopted, a micro MEMS pressure sensor array is integrated, and sub-Newton level force control precision is achieved through a double-closed-loop PID control algorithm. The system comprises a miniature force sensor integration module, a dynamic force feedback control module and an edge-lower support fusion type clamping jaw structure, and can effectively solve the problems of stress concentration, temperature deformation and the like in the ultrathin wafer carrying process. The control method disclosed by the invention is combined with a working condition self-adaptive adjustment strategy, supports modes of sensitive edge protection, pressure balance, high-speed stability and the like, can switch working modes in real time according to wafer states and environmental conditions, dynamically adjusts operation parameters, and provides a solution for precise carrying of third-generation semiconductor ultrathin materials.

Description

A wafer adaptive gripping system and method based on dynamic force feedback Technical Field

[0001] This invention belongs to the field of semiconductor material processing and handling technology, specifically relating to a wafer gripping system and its control method. This invention is applicable to the precision handling of wafers made of third-generation semiconductor materials such as silicon carbide and gallium nitride, and is particularly useful for the precise gripping and safe handling of ultra-thin wafers during the manufacturing process. Background Technology

[0002] In the semiconductor manufacturing field, the precise gripping and safe handling of ultrathin wafers are crucial to product yield and production efficiency. In recent years, with the rapid development of third-generation semiconductor technology, wide-bandgap semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) have been widely used in high-frequency, high-power, and high-temperature electronic devices. These ultrathin wafers (thickness <100μm) possess unique mechanical properties, posing numerous technical challenges to their gripping operations.

[0003] Third-generation semiconductor wafers generally exhibit high hardness, high brittleness, and low bending strength, posing dual requirements for stable handling and surface protection in wafer handling devices. Currently, existing technologies in the wafer gripping field mainly fall into the following categories:

[0004] (1) Force sensor-based gripping scheme. For example, patent CN117096088B discloses a wafer handling device that uses a pressure sensor on a suction cup to detect changes in vacuum pressure between the suction cup and the wafer contact surface. When this type of scheme is applied to ultra-thin wafers, further optimization of force control resolution needs to be considered.

[0005] (2) Gripping devices with a single clamping method. For example, patent CN117381819A discloses an edge-clamping wafer pick-and-place robotic arm that uses the edge clamping principle. This clamping method requires high precision in the mechanical structure, and the clamping stability depends on the uniformity of pressure. When handling or processing irregularly shaped wafers at high speeds, there is a risk of slippage or local stress concentration.

[0006] (3) The clamping device lacks adaptability in its structural design. For example, the wafer transfer mechanical clamping device disclosed in patent CN222637272U adopts a rigid clamping structure with fixed parameters. In mixed-line production environments, when different specifications of wafers need to be processed, it is necessary to adjust the equipment parameters or replace the clamps, which affects production efficiency to some extent.

[0007] Based on a comprehensive analysis of the existing technologies, current wafer gripping technologies still face the following technical challenges in handling ultra-thin wafers for third-generation semiconductors:

[0008] First, there are requirements for clamping structures. Existing single clamping methods cannot simultaneously meet the requirements of handling stability and material protection, especially for ultra-thin wafers. This is mainly because single clamping methods are prone to stress concentration, lack comprehensive control over the overall stress state of the wafer, and cannot effectively prevent micro-deformation. Therefore, it is necessary to develop new clamping structures that can disperse stress and prevent deformation to reduce breakage rates and improve handling stability.

[0009] Second, there is the requirement for force control accuracy. The force control resolution and detection coverage of existing sensor systems are insufficient to meet the high-precision control requirements of ultra-thin wafers. For ultra-thin wafers with a thickness of less than 100 μm, their sensitivity to minute force changes is significantly increased, requiring more precise force control. Therefore, it is necessary to develop a force control system with higher accuracy and a wider detection range to achieve accurate monitoring and adjustment of the stress state of the wafer.

[0010] Third, the need for adaptive capabilities. Existing equipment has limited responsiveness to changes in the environment and wafer condition, making it difficult to meet the requirements of high-speed, high-precision production. This is mainly reflected in the fact that fixed parameter designs cannot cope with wafers of different materials, thicknesses, and surface conditions, and lack a mechanism for dynamic adjustment based on real-time data. Therefore, it is necessary to develop a control system with adaptive capabilities that can optimize and capture parameters in real time according to changes in wafer characteristics and environmental conditions.

[0011] Therefore, developing an ultrathin wafer adaptive gripping system that can meet the above-mentioned technical requirements has significant engineering application value and industrialization prospects for improving the yield and efficiency of third-generation semiconductor material manufacturing processes. Summary of the Invention

[0012] The purpose of this invention is to address the problems of insufficient force control precision, limited single clamping structure, and insufficient adaptive capability in existing ultrathin wafer gripping technologies, and to provide a wafer adaptive gripping system and method based on dynamic force feedback, so as to achieve sub-Newton level precise gripping, stable handling, and safe release of third-generation semiconductor ultrathin wafers.

[0013] To achieve the above objectives, the present invention adopts the following technical solution: a wafer adaptive gripping system based on dynamic force feedback, comprising an edge-support fused gripper structure, a micro force sensor integrated module, and a dynamic force feedback control module.

[0014] An edge-support fused gripper structure includes an upper edge gripping mechanism and a lower support platform, wherein the edge gripping mechanism and the lower support platform work together to grip the wafer;

[0015] A miniature force sensor integrated module is disposed on the edge clamping mechanism and the lower support platform for real-time acquisition of wafer force distribution data;

[0016] The dynamic force feedback control module is electrically connected to the integrated module of the micro force sensor. It adopts a dual closed-loop PID control algorithm. The outer loop controller calculates the overall adjustment based on the force distribution deviation and force distribution uniformity, while the inner loop controller performs force tracking control and combines it with vibration suppression compensation. The outer loop PID parameters are adaptively adjusted according to the wafer thickness, and the inner loop PID parameters are dynamically optimized according to the material properties. This controls the edge clamping mechanism and the lower support platform to adjust the clamping force distribution on the wafer.

[0017] Furthermore, the edge clamping mechanism includes a left gripper and a right gripper arranged opposite to each other; the lower support platform includes a ceramic substrate and a fine-tuning lifting mechanism, the surface of the ceramic substrate forms a support structure and integrates an air flotation system, the air flotation system includes a micro nozzle array, the micro nozzle array forms a support air cushion; the fine-tuning lifting mechanism is disposed in a first groove below the ceramic substrate and is used to adjust the position and orientation of the ceramic substrate.

[0018] Furthermore, the left and right grippers of the edge clamping mechanism have a multi-level gradient stiffness structure, which, from the outside to the inside, consists of:

[0019] The outer elastic material layer has a surface processed with multiple microgrooves;

[0020] A lightweight middle reinforcement material layer;

[0021] The inner sensor and thermally conductive module layer are used to acquire data and prevent thermal stress.

[0022] Furthermore, the number of microgrooves is 3 to 8, the width is 0.2 to 0.5 mm, the hardness of the outer elastic material layer is Shore 40A to Shore 90A, and the thickness is 1 mm to 2 mm; the thickness of the middle reinforcing material layer is 2 mm to 4 mm.

[0023] Furthermore, the surface support structure of the ceramic substrate is a multi-point support structure; it is provided with multiple second mounting grooves; the fine-tuning lifting mechanism is a precision linear platform composed of piezoelectric motors, arranged in the first mounting groove and the second mounting groove.

[0024] Furthermore, the micro force sensor integrated module includes:

[0025] The sensor array distributed in the edge clamping mechanism and the lower support platform consists of multiple silicon-based piezoresistive MEMS sensors;

[0026] The signal conditioning circuit, electrically connected to the sensor array, is used to amplify and filter the sensor signals;

[0027] The data acquisition unit, electrically connected to the signal conditioning circuit, is used for analog-to-digital conversion and data buffering.

[0028] The edge processor, electrically connected to the data acquisition unit, is used for preliminary processing and feature extraction of sensor data.

[0029] Furthermore, the dynamic force feedback control module includes:

[0030] The outer loop controller receives data transmitted by the micro force sensor integrated module and uses it to extract geometric features such as force deviation, center of gravity deviation, and uniformity deviation.

[0031] The inner loop execution unit receives parameters from the outer loop controller for force tracking and vibration suppression;

[0032] An inertial measurement unit is used to monitor the vibration and attitude of the edge-lower fused gripper structure;

[0033] A material property database stores deformation property data of wafer materials, providing reference data for the outer loop controller.

[0034] A wafer adaptive gripping method based on dynamic force feedback includes the following steps:

[0035] Step S1: Initialize the system, load wafer parameters and set control parameters;

[0036] Step S2: Cooperative clamping, controlling the lower support platform and the edge clamping mechanism to contact the wafer in a preset order and establish an initial clamping force;

[0037] Step S3: Dynamic adjustment. Based on the feedback data from the micro force sensor integrated module, the force distribution ratio and clamping force between the edge clamping mechanism and the lower support platform are adjusted in real time.

[0038] Step S4: Precise release. Based on sensor feedback, the system first reduces the edge clamping force while maintaining stable lower support to ensure a smooth transition of the wafer. The lower support platform descends slowly to achieve impact-free wafer release.

[0039] Furthermore, step S3 includes switching between the following operating modes based on the wafer state and operating condition requirements:

[0040] Sensitive edge protection mode: When microcracks or chips are detected at the edge of the wafer, the clamping force in the corresponding area is reduced, while the lower support ratio is increased.

[0041] In the balanced pressure mode, when wafer warping is detected, the distribution of the lower support points is adjusted to form a uniform support force distribution;

[0042] In high-speed stable mode, when the wafer handling speed or acceleration exceeds a preset threshold, the system will adjust according to the formula. Increase the edge clamping force ratio, of which Edge clamping force ratio The upper limit is 60%, and the controller response speed is improved.

[0043] The beneficial effects of this invention are:

[0044] (1) Precise Force Control and Monitoring Effect. This invention utilizes silicon-based piezoresistive MEMS sensor array technology to achieve high-resolution sub-Newton force measurement, significantly improving force control accuracy compared to conventional technologies. The dual-closed-loop PID control algorithm combined with force distribution analysis technology enables the system to monitor the force distribution state of the wafer in real time and make precise adjustments. Furthermore, the system's dynamic adjustment capability for force distribution makes it applicable to wafers of different materials and thicknesses, enhancing the system's versatility and stability, especially when processing ultra-thin wafers made of third-generation semiconductor materials such as silicon carbide and gallium nitride.

[0045] (2) Effect of the integrated clamping structure. This invention proposes an edge-bottom support integrated clamping structure, which organically combines edge clamping and bottom support technologies to form a complementary mechanical advantage. Through multi-level gradient stiffness design and three-point support air buoyancy technology, this structure achieves dynamic adjustment of the force balance between the edge and the bottom, and the force distribution ratio can be automatically optimized when clamping conditions change. This integrated structure can improve the handling speed while maintaining stable clamping and helps to improve the stress concentration phenomenon at the wafer edge. It is especially suitable for the precision handling of large-size ultra-thin wafers (thickness <100μm), breaking through the limitations of single clamping methods when dealing with ultra-thin wafers.

[0046] (3) Adaptive Control. The adaptive control system developed in this invention can adjust the force distribution ratio and clamping force between the edge clamping mechanism and the lower support platform in real time according to the wafer state and environmental conditions, and switch working modes in real time, such as sensitive edge protection, balanced pressure, and high-speed stability modes, so that the system can maintain optimal operating parameters under different working conditions. Especially when processing sensitive wafers with microcracks or irregular surfaces, the system can reduce the clamping force in specific areas and redistribute the support force, reducing operational risks. This improves the adaptability to the production environment and the ability to operate continuously.

[0047] In summary, this invention overcomes the technical challenges in the handling of ultra-thin wafers for third-generation semiconductors through system integration innovation, improving the yield and efficiency of wafer handling, and is suitable for high-precision automated production of third-generation semiconductor materials. Attached Figure Description

[0048] Instruction manual illustrations

[0049] Figure 1 is a partial cross-sectional schematic diagram of the wafer adaptive gripping system based on dynamic force feedback of the present invention;

[0050] Figure 2 is a cross-sectional view of the edge gripper structure, which shows the multi-level gradient stiffness structure and the arrangement of the MEMS sensor array and temperature sensor.

[0051] Figure 3 is an exploded view of the lower support platform, which shows the installation method of the three-point fine-tuning lifting mechanism;

[0052] Figure 4 is a cross-sectional view of the lower support platform, which shows the micro-nozzle array, the three-point support structure and the MEMS sensor array;

[0053] Figure 5 shows the system initialization phase of the wafer adaptive gripping method based on dynamic force feedback;

[0054] Figure 6 shows the initial contact stage of the wafer adaptive gripping method system based on dynamic force feedback;

[0055] Figure 7 shows the dynamic switching stage of the wafer adaptive gripping system based on dynamic force feedback in terms of clamping and working mode.

[0056] Figure 8 shows the differences in pose and force distribution of the edge-lower support fused gripper of the present invention in sensitive edge protection mode;

[0057] Figure 9 shows the differences in pose and force distribution of the edge-lower support fused gripper of the present invention in the balanced pressure mode;

[0058] Figure 10 shows the differences in pose and force distribution of the edge-lower support fused gripper of the present invention in high-speed stable mode;

[0059] Figure 11 is a flowchart of the dynamic force feedback control algorithm of the present invention, showing the complete control process from sensor data acquisition to force control execution.

[0060] The meanings of the labeled components in the diagram are as follows:

[0061] 1-Edge-bottom support integrated gripper structure; 2-Ultra-thin wafer; 11-Edge gripping mechanism; 12-Bottom support platform; 111-Left gripper; 112-Right gripper; 1111-Outer elastic material layer; 1112-Middle reinforcement material layer; 1113-Inner MEMS sensor array; 114-Gripping force direction; 121-Ceramic substrate; 122-Micro nozzle array; 123-Piezoelectric motor; 124-Upper MEMS sensor array; 125-Air buoyancy; 126-First mounting groove; 127-Second mounting groove. Detailed Implementation

[0062] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0063] It should be understood that the following detailed description is exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art.

[0064] Please refer to Figures 1 to 5. This invention provides an embodiment: a wafer adaptive gripping system based on dynamic force feedback, comprising an edge-support fused gripper structure, a micro force sensor integrated module, and a dynamic force feedback control module.

[0065] An edge-support fused gripper structure includes an upper edge gripping mechanism and a lower support platform, wherein the edge gripping mechanism and the lower support platform work together to grip the wafer;

[0066] A miniature force sensor integrated module is disposed on the edge clamping mechanism and the lower support platform for real-time acquisition of wafer force distribution data;

[0067] The dynamic force feedback control module is electrically connected to the integrated module of the micro force sensor and adopts a dual closed-loop control strategy. The outer loop controller calculates the overall adjustment amount based on the force distribution deviation and force distribution uniformity, while the inner loop controller performs force tracking control and combines vibration suppression compensation. The outer loop PID parameters are adaptively adjusted according to the wafer thickness, and the inner loop PID parameters are dynamically optimized according to the material properties. This controls the edge clamping mechanism and the lower support platform to adjust the clamping force distribution on the wafer.

[0068] Please refer to Figure 5. In one embodiment of the present invention, the edge clamping mechanism includes a left gripper and a right gripper arranged opposite to each other; the lower support platform includes a ceramic substrate and a fine-tuning lifting mechanism. The surface of the ceramic substrate forms a support structure and integrates an air flotation system. The air flotation system includes a micro-nozzle array, which forms a supporting air cushion; the fine-tuning lifting mechanism is disposed in a first mounting groove below the ceramic substrate and is used to adjust the position and orientation of the ceramic substrate. The lower support platform uses a ceramic material substrate with a small central bulge forming a support structure, and the integrated micro-nozzle array provides a supporting air cushion with a thickness of 0.02~0.05mm.

[0069] Please refer to Figure 5. In one embodiment of the present invention, the left and right grippers of the edge clamping mechanism have a multi-level gradient stiffness structure, which, from the outside to the inside, consists of:

[0070] The outer elastic material layer has a surface processed with multiple microgrooves;

[0071] A lightweight middle reinforcement material layer;

[0072] The inner sensor and thermally conductive module layer are used to acquire data and prevent thermal stress.

[0073] Please refer to Figure 5. In one embodiment of the present invention, the number of microgrooves is 3 to 8, and the width is 0.2 to 0.5 mm; the hardness of the outer elastic material layer is Shore 40A to Shore 90A, and the thickness is 1 mm to 2 mm; the thickness of the middle reinforcing material layer is 2 mm to 4 mm.

[0074] Please refer to Figure 5. In one embodiment of the present invention, the surface support structure of the ceramic substrate is a multi-point support structure; it has multiple second mounting grooves underneath; the fine-tuning lifting mechanism is a precision linear platform composed of piezoelectric motors, arranged in the first and second mounting grooves. The multi-point fine-tuning lifting mechanism can be a three- to nine-point support structure, and can achieve precise height adjustment. The piezoelectric motor is model Q-545.

[0075] Please refer to Figure 5. In one embodiment of the present invention, the micro force sensor integrated module includes:

[0076] The sensor array distributed on the edge clamping mechanism and the lower support platform consists of multiple silicon-based piezoresistive MEMS sensors; the edge clamping mechanism is equipped with an inner layer MEMS sensor array, and the lower support platform is equipped with a layer MEMS sensor array; the MEMS sensors are silicon-based piezoresistive MEMS sensors, which can be 5 to 20, used to collect wafer stress distribution data in real time, with a single sensor size of 0.5mm × 0.5mm and a resolution of 0.05N.

[0077] The signal conditioning circuit, electrically connected to the sensor array, is used to amplify and filter the sensor signals;

[0078] The data acquisition unit, electrically connected to the signal conditioning circuit, is used for analog-to-digital conversion and data buffering.

[0079] The edge processor, electrically connected to the data acquisition unit, is used for preliminary processing and feature extraction of sensor data.

[0080] Please refer to Figure 5. In one embodiment of the present invention, the dynamic force feedback control module includes:

[0081] The outer loop controller receives data transmitted from the micro force sensor integrated module and extracts geometric features such as force deviation, center of gravity deviation, and uniformity deviation. The outer loop controller runs a force distribution analysis algorithm based on the edge computing module to calculate the overall clamping force adjustment in real time.

[0082] The inner loop execution unit receives parameters from the outer loop controller for force tracking and vibration suppression. The inner loop execution unit uses a voice coil motor and a 2000-line incremental encoder to achieve force tracking and vibration suppression.

[0083] An inertial measurement unit is used to monitor the vibration and attitude of the edge-lower fused gripper structure;

[0084] A material property database stores deformation characteristic data of wafer materials, providing reference data for the outer loop controller. Combined with an inertial measurement unit for monitoring the vibration and attitude of the edge-support fused gripper structure and the material property database storing wafer material deformation characteristic data, the system dynamically adjusts PID parameters to control the edge gripping mechanism and the lower support platform to adjust the clamping force distribution on the wafer.

[0085] Please refer to Figures 1 to 5. This invention provides an embodiment: a wafer adaptive gripping method based on dynamic force feedback, comprising the following steps:

[0086] Step S1: Initialize the system, load wafer parameters and set control parameters; parameters include material type, thickness, diameter, etc., initialize PID control parameters, and set the clamping force adaptive threshold; the lower support platform first approaches the wafer, and the air flotation system is activated to form an air cushion of 0.02~0.05mm thickness;

[0087] Step S2: Cooperative clamping. The lower support platform and the edge clamping mechanism are controlled to contact the wafer in a preset order and establish an initial clamping force. After the MEMS sensor detects the contact, the lower support platform stops rising. The edge clamping mechanism slowly approaches the edge of the wafer, and the MEMS sensor array monitors the gripping force distribution in real time. The edge clamping force increases slowly. Dual closed-loop PID control is started to suppress vibration and overshoot.

[0088] Step S3: Dynamic adjustment. Based on the feedback data from the integrated micro force sensor module, the force distribution ratio and clamping force between the edge clamping mechanism and the lower support platform are adjusted in real time. The system switches operating modes in real time based on the feedback data from the micro force sensor: Sensitive edge protection mode: When microcracks or chips are detected at the edge, the clamping force in that area is reduced, and the lower support ratio is increased to 80%; Balanced pressure mode: When wafer warping is detected, the distribution of lower support points is adjusted to form a uniform support force distribution; High-speed stable mode: When the wafer handling speed or acceleration exceeds a preset threshold, the edge clamping force ratio is increased and the controller response speed is improved.

[0089] Step S4: Precise Release. Based on sensor feedback, the system first reduces the edge clamping force while maintaining stable lower support to ensure a smooth wafer transition. The lower support platform descends slowly, achieving impact-free wafer release.

[0090] Please refer to Figure 5. In one embodiment of the present invention, step S3 includes switching between the following operating modes according to the wafer state and operating requirements:

[0091] Sensitive edge protection mode: When microcracks or chips are detected at the edge of the wafer, the clamping force in the corresponding area is reduced, while the lower support ratio is increased.

[0092] In the balanced pressure mode, when wafer warping is detected, the distribution of the lower support points is adjusted to form a uniform support force distribution;

[0093] In high-speed stable mode, when the wafer handling speed or acceleration exceeds a preset threshold, the system will adjust according to the formula. Increase the edge clamping force ratio, of which Edge clamping force ratio The upper limit is 60%, and the controller response speed is improved.

[0094] Example 1

[0095] As shown in Figures 1, 2, and 3, the wafer adaptive gripping system based on dynamic force feedback of the present invention mainly includes a micro force sensor integrated module, an edge-support fused gripper structure, and a dynamic force feedback control module. The modules are connected via a control bus to achieve data interaction and collaborative operation.

[0096] The edge-support fusion gripper structure is designed with a "Π"-shaped main frame, including an upper edge gripping mechanism and a lower support platform. The edge gripping mechanism adopts a multi-level gradient stiffness structure, with an outer elastic material layer made of 1mm thick food-grade silicone. Five microgrooves with a width of 0.2mm and a spacing of 0.2mm are machined on the surface to increase friction, and the edge areas are rounded. The middle reinforcing material layer is 2mm thick carbon fiber reinforced plastic, employing a lightweight honeycomb structure. The inner sensor and thermal module layer integrates an inner MEMS sensor array and a thermal module, effectively avoiding the impact of electrostatic adsorption on the wafer.

[0097] The lower support platform uses an alumina ceramic material base with a thickness of 5mm and a coefficient of thermal expansion of <7×10. -6 / K. A small protrusion is formed in the central area using precision machining technology to achieve a three-point support structure. A micro-nozzle array with a diameter of 0.1 mm and a spacing of 5 mm is created using laser drilling and connected to the gas supply system. An upper-layer MEMS sensor array is embedded and mounted through through-holes on the back of the ceramic substrate to monitor the contact status of the wafer's bottom surface. The three-point fine-tuning lifting mechanism consists of a Q-545 piezoelectric motor with a piezoelectric ceramic actuator, achieving a stroke accuracy of ±2 μm and a maximum stroke of 200 μm.

[0098] The miniature force sensor integrated module includes a sensor array, signal conditioning circuitry, data acquisition unit, and edge processor. The sensor array is manufactured using silicon-based piezoresistive MEMS technology. Each sensor measures 0.5mm × 0.5mm, has a resolution of 0.05N, and a measurement range of 0–5N. They are arranged in a 20 × 20 array on a 20mm × 20mm contact surface. 0.05mm thick stainless steel micro-spring sheets are embedded in the edge region to suppress sensor overload caused by excessive substrate deformation.

[0099] The dynamic force feedback control module includes an outer loop controller, an inner loop execution unit, an IMU (Inertial Measurement Unit), and a control algorithm library. The outer loop controller, based on an edge computing module, runs a force distribution analytical algorithm at a frequency of 200Hz, calculating the overall clamping force adjustment in real time. The IMU employs a six-axis sensor design with an accelerometer range of ±8g and a gyroscope range of ±2000° / s, used to monitor the gripper's vibration attitude; the data is used for inner loop vibration suppression compensation.

[0100] The inner loop actuator uses a voice coil motor paired with a 2000-line incremental encoder to achieve force tracking and vibration suppression, with a response frequency of up to 500Hz. The control algorithm library includes contact physics modeling and pre-stored 3D deformation databases for materials such as SiC and GaN. Based on this database, the system can dynamically adjust PID parameters to optimize response speed and stability.

[0101] Example 2

[0102] This embodiment provides a wafer adaptive gripping method based on dynamic force feedback. Its workflow is shown in Figure 10: The system is first initialized, and wafer parameters and PID parameters are loaded. When the lower support platform approaches, the air flotation system is activated to form an air cushion. The pressure sensor detects whether the lower support platform is in contact with the wafer. The edge clamping mechanism is activated and the force distribution is monitored through the internal MEMS sensor array. Dual closed-loop PID control is adopted, and the clamping mode is adjusted according to different wafer states and working conditions to finally complete the gripping.

[0103] 1. System Initialization Phase

[0104] As shown in Figure 4, system initialization includes two main steps: parameter loading and air flotation preparation.

[0105] (1) Parameter loading: The system loads wafer parameters (material type, thickness, diameter, etc.) and sets the corresponding initial PID control parameters. At the same time, the system sets the clamping force adaptive threshold, which is usually 1.2 to 1.5 times the slip critical force.

[0106] (2) Air flotation preparation: The lower support platform first approaches the wafer, maintaining a distance of 5~10mm. Start the air flotation system, set the air source pressure to 0.2~0.3MPa, and form an air cushion of 0.02~0.05mm thickness through the micro nozzle array to reduce friction and prepare for initial contact.

[0107] 2. Initial Contact and Clamping Phase

[0108] As shown in Figures 5 and 6, the initial contact and clamping process includes two steps: contact detection and force-controlled clamping.

[0109] (1) Contact detection: The lower support platform rises slowly at a speed of 0.5 mm / s. After the upper MEMS sensor array detects contact (pressure > 0.05 N), the lower support platform immediately stops rising and maintains its current position, with the accuracy controlled within ±2 μm.

[0110] (2) Force-controlled clamping: The edge clamping mechanism slowly approaches the wafer edge at a speed of 1 mm / s, and the inner MEMS sensor array monitors the contact force and spatial distribution in real time. The edge clamping force slowly increases to the range of 0.5~1N at a rate of 0.5N / s, and at the same time, dual closed-loop PID control is started. The outer loop updates the force distribution calculation results at a frequency of 50Hz, and the inner loop performs force tracking control at a frequency of 200Hz to suppress vibration and overshoot and ensure the stability of the clamping process.

[0111] 3. Dynamic switching phase of working modes

[0112] As shown in Figures 7, 8, and 9, the system switches between different operating modes in real time based on sensor feedback data to adapt to different wafer states and operating conditions.

[0113] (1) Sensitive edge protection mode: When the sensor array detects microcracks or chipping at the edge of the wafer (local stress anomaly, pressure gradient > 0.5 N / mm), the system automatically switches to this mode. At this time, the clamping force in this area is reduced to below 0.8 N, while the air buoyancy ratio of the lower support is increased to 80%. At the same time, the rise height of the lower support platform is adjusted by about 0.05~0.1 mm to form a more balanced support distribution.

[0114] (2) Balanced pressure mode: When the system detects that the wafer warpage exceeds the threshold, it automatically switches to this mode. At this time, the system adjusts the distribution of the lower support points, and the height difference of the three support structures is dynamically adjusted to form a more uniform support force distribution, avoiding the aggravation of wafer deformation. At the same time, the edge clamping force is kept at a low level (1~2N) to reduce additional stress.

[0115] (3) High-speed stable mode: The system enters this mode when the handling speed increases (>200mm / s) or the acceleration increases (>0.5g). At this time, the edge clamping force ratio is increased to 40% (normally 30%), and the lower support air buoyancy ratio is reduced to 60% accordingly. At the same time, the response speed of the PID controller is improved by increasing the proportional gain by 20% and the derivative gain by 50% to respond quickly to dynamic changes. The data weight of the IMU inertial measurement unit is increased to enhance the vibration suppression function.

[0116] 4. Safe release phase

[0117] (1) Release preparation: The system calculates the optimal release strategy based on sensor feedback and target position information to ensure a smooth transition of the wafer to a stationary state.

[0118] (2) Force-controlled release: The system first reduces the edge clamping force to 50% of the initial contact force (approximately 0.3~0.5N) while maintaining the stability of the lower support. Then, the edge clamping force is further reduced to zero at a rate of 0.3N / s to achieve complete release of the edge clamping.

[0119] (3) Lower support separation: After the edge clamps are completely detached, the lower support platform slowly descends at a speed of 0.5 mm / s, while the air flotation system continues to operate to reduce friction during the separation process. When the sensor detects that the contact force has completely disappeared, the lower support platform continues to descend by 5~10 mm to ensure complete separation and achieve impact-free wafer release.

[0120] Example 3

[0121] This embodiment provides an optimized grasping method for SiC / GaN heterostructure wafers.

[0122] (1) Sensor array optimization configuration: In view of the characteristics of SiC / GaN heterostructure, a higher density sensor array is configured in the edge clamping area, the sensor spacing in the GaN layer contact area is 0.8mm and 30 high-precision sensors are configured, and the sensor spacing in the SiC substrate contact area is 1.5mm and 10 standard sensors are configured; a greater sensor density is achieved in the key GaN area.

[0123] (2) Differentiated clamping strategy: Based on the material property database, the system adopts different clamping parameters for the SiC substrate region and the GaN epitaxial layer region. The clamping force in the SiC substrate region is set in the range of 2~4N, while that in the GaN epitaxial layer region is controlled in the range of 0.5~1N, so as to ensure stable clamping while minimizing stress damage to the brittle GaN layer.

[0124] (3) Special edge protection: In view of the easy peeling of GaN layer at the edge of SiC / GaN wafer, the thickness of the outer silicone layer of the edge clamping structure is increased to 1.5mm and the hardness is reduced to Shore 50A. At the same time, a progressive clamping strategy is adopted, and the clamping force gradually increases from the edge to the center, forming a force gradient of 0.2~0.8N, which effectively prevents edge peeling damage.

[0125] Example 4

[0126] This embodiment provides a high-speed transport method for ultra-thin wafers (thickness <50μm). (1) Enhanced air flotation system: In view of the characteristics of ultra-thin wafers being more easily deformed, the pressure of the air flotation system is increased to 0.4MPa, the density of the micro-nozzle array is doubled (the spacing is reduced to 2.5mm), forming a uniform air cushion of 0.03~0.06mm thickness, reducing the contact area between the wafer and the support surface.

[0127] (2) Optimization of dual closed-loop PID parameters: In response to the force-deformation curve characteristics of ultra-thin wafers, the outer loop PID parameters are set by increasing the proportional coefficient and the derivative coefficient, and decreasing the integral coefficient to improve the system's response speed to transient changes, while avoiding stress damage caused by overshoot.

[0128] (4) Multi-point support structure: The lower support platform is upgraded from three-point support to five-point support. Dynamic air pressure adjustment technology is adopted to adjust the support force of each support point in real time according to the wafer deformation state, forming a more uniform force distribution. The maximum support force difference is controlled within ±0.1N, which effectively prevents excessive deformation of ultra-thin wafers during high-speed handling.

[0129] Through the above technical measures, the system can safely transport ultra-thin wafers with a thickness of only 30μm at high speeds, with positional accuracy controlled within ±0.05mm, significantly improving the production efficiency of ultra-thin wafer manufacturing.

Claims

1. A wafer adaptive gripping system based on dynamic force feedback, comprising an edge-support fused gripper structure, a micro force sensor integrated module, and a dynamic force feedback control module, characterized in that: An edge-support fusion gripper structure includes an upper edge gripping mechanism and a lower support platform, which work together to grip the wafer. A micro force sensor integrated module is mounted on the edge gripping mechanism and the lower support platform to collect real-time force distribution data of the wafer. A dynamic force feedback control module is electrically connected to the micro force sensor integrated module and adopts a dual closed-loop PID control algorithm. The outer loop controller calculates the overall adjustment based on force distribution deviation and force distribution uniformity, while the inner loop controller performs force tracking control combined with vibration suppression compensation. The outer loop PID parameters are adaptively adjusted according to the wafer thickness, and the inner loop PID parameters are dynamically optimized according to material properties, controlling the edge gripping mechanism and the lower support platform to adjust the gripping force distribution on the wafer.

2. The wafer adaptive gripping system based on dynamic force feedback according to claim 1, characterized in that, The edge clamping mechanism includes a left clamp and a right clamp arranged opposite to each other; the lower support platform includes a ceramic substrate and a fine-tuning lifting mechanism, the surface of the ceramic substrate forms a support structure and integrates an air flotation system, the air flotation system includes a micro nozzle array, the micro nozzle array forms a support air cushion; the fine-tuning lifting mechanism is disposed in a first mounting groove below the ceramic substrate and is used to adjust the position and orientation of the ceramic substrate.

3. The wafer adaptive gripping system based on dynamic force feedback according to claim 2, characterized in that, The left and right grippers of the edge clamping mechanism have a multi-level gradient stiffness structure, which consists of, from the outside to the inside: an outer elastic material layer with multiple microgrooves on its surface; and a middle reinforcing material layer with a lightweight structure. The inner sensor and thermally conductive module layer are used to acquire data and prevent thermal stress.

4. The wafer adaptive gripping system based on dynamic force feedback according to claim 3, characterized in that: The number of microgrooves is 3 to 8, the width is 0.2 to 0.5 mm, the hardness of the outer elastic material layer is Shore 40A to Shore 90A, and the thickness is 1 mm to 2 mm; the thickness of the middle reinforcing material layer is 2 mm to 4 mm.

5. A wafer adaptive gripping system based on dynamic force feedback according to claim 2, characterized in that, The surface support structure of the ceramic substrate is a multi-point support structure, and multiple second mounting grooves are provided under the multi-point support structure; the fine-tuning lifting mechanism is a precision linear platform composed of piezoelectric motors, which is arranged in the first mounting groove and the second mounting groove.

6. The wafer adaptive gripping system based on dynamic force feedback according to claim 1, characterized in that, The micro force sensor integrated module includes: a sensor array distributed on the edge clamping mechanism and the lower support platform, consisting of multiple silicon-based piezoresistive MEMS sensors; a signal conditioning circuit electrically connected to the sensor array for amplifying and filtering sensor signals; a data acquisition unit electrically connected to the signal conditioning circuit for analog-to-digital conversion and data caching; and an edge processor electrically connected to the data acquisition unit for preliminary processing and feature extraction of sensor data.

7. The wafer adaptive gripping system based on dynamic force feedback according to claim 1, characterized in that, The dynamic force feedback control module includes: an outer loop controller, which receives data transmitted by the micro force sensor integrated module and is used to extract geometric features such as force deviation, center of gravity deviation, and uniformity deviation; an inner loop execution unit, which receives parameters from the outer loop controller and is used for force tracking and vibration suppression; an inertial measurement unit, which is used to monitor the vibration and attitude of the edge-lower support fused gripper structure; and a material property database, which stores deformation property data of the wafer material and provides reference data for the outer loop controller.

8. A method applicable to the wafer adaptive gripping system based on dynamic force feedback as described in any one of claims 1-7, characterized in that, Includes the following steps: Step S1: Initialize the system, load wafer parameters, and set control parameters; Step S2: Cooperative clamping, control the lower support platform and the edge clamping mechanism to contact the wafer in a preset order, and establish an initial clamping force; Step S3: Dynamic adjustment, adjust the force distribution ratio and clamping force of the edge clamping mechanism and the lower support platform in real time according to the feedback data of the micro force sensor integrated module; Step S4: Precise release, the system first reduces the edge clamping force according to the sensor feedback, while maintaining the stability of the lower support to ensure a smooth transition of the wafer; the lower support platform descends slowly to achieve impact-free release of the wafer.

9. The wafer adaptive gripping method according to claim 8, characterized in that, Step S3 includes switching between the following working modes according to the wafer state and working conditions: Sensitive edge protection mode, when microcracks or chips are detected at the wafer edge, the clamping force in the corresponding area is reduced, while the lower support ratio is increased. In the balanced pressure mode, when wafer warping is detected, the distribution of the lower support points is adjusted to form a uniform support force distribution. In the high-speed stable mode, when the wafer handling speed or acceleration exceeds the preset threshold, the edge clamping force ratio is increased according to the formula R_edge=R_baseline+(speed_factor-1.0)×0.25, where speed_factor=1.0+0.8×√(((v / 100mm / s)²+(a / 0.2g)²)), the upper limit of the edge clamping force ratio R_edge is 60%, and the controller response speed is improved.

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