Integrated multi-beam synchronous femtosecond laser implicit cutting and automatic stripping integrated device

Abstract

The invention belongs to the technical field of semiconductor material processing, and particularly relates to an integrated multi-beam synchronous femtosecond laser implicit cutting and automatic stripping integrated device, which comprises a femtosecond laser light source module used for generating a single path of femtosecond laser; the multi-beam femtosecond laser implicit cutting module comprises a spatial light modulator, a beam splitting prism group and a beam scanning control unit which are sequentially arranged along a light path; a spatial light modulator and a beam splitter prism group are used for dividing the single-path laser into multiple parallel sub-beams; and the light beam scanning control unit is used for driving the plurality of sub light beams to execute radial synchronous scanning on the same focal plane in the crystal ingot along a plurality of preset concentric circular ring paths. The implicit cutting efficiency can be greatly improved through multi-beam parallel scanning, controllable damage-free automatic stripping is achieved through thermal stress induction, and full-process automatic and intelligent machining from a crystal ingot to a wafer is achieved through a highly-integrated automatic module and digital twin monitoring.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor material processing technology, specifically relating to an integrated multi-beam synchronous femtosecond laser slicing and automatic stripping device. Background Technology

[0002] Silicon carbide (SiC), as a third-generation wide-bandgap semiconductor material, possesses excellent properties such as a large bandgap, high thermal conductivity, high breakdown field strength, and fast electron saturation drift velocity, making it irreplaceable in applications such as new energy vehicles, rail transportation, smart grids, and aerospace. Substrate preparation is the core step in SiC device manufacturing, and its processing precision and efficiency directly determine device performance and production costs.

[0003] In the third-generation semiconductor industry, the fabrication technology of silicon carbide (SiC) substrates directly restricts the industrialization process of high-frequency, high-temperature, and high-power devices. With the surge in demand for high-efficiency power devices from global sectors such as new energy vehicles, photovoltaic inverters, and rail transportation, the market demand for 4-8 inch large-size SiC substrates is growing at an average annual rate of over 30%, while simultaneously placing more stringent requirements on substrate processing efficiency, surface quality, and production costs. However, current SiC ingot peeling technology still faces many bottlenecks that urgently need to be overcome, making it difficult to keep pace with the industry's development.

[0004] Problems with existing technology: Despite the advanced principles of femtosecond laser slicing technology, existing solutions still have significant shortcomings in its industrial applications, especially for the efficient and high-consistency manufacturing of large-size wafers. Currently, the mainstream industrial solutions for slicing primarily employ a single-beam femtosecond laser combined with a two-dimensional scanning galvanometer. When dealing with ingots of 4 inches or larger, and requiring the fabrication of entire wafers, one or more large-diameter closed-loop modified layers must be scanned within the ingot. The single-beam scanning method means that the total processing path length is linearly proportional to the processing area, leading to a sharp increase in processing time as the wafer size increases. Summary of the Invention

[0005] The purpose of this invention is to provide an integrated multi-beam synchronous femtosecond laser slicing and automatic stripping device, which can significantly improve slicing efficiency through multi-beam parallel scanning, achieve controllable and damage-free automatic stripping through thermal stress induction, and realize fully automated and intelligent processing from ingot to wafer through highly integrated automation modules and digital twin monitoring.

[0006] The specific technical solution adopted by this invention is as follows: An integrated multi-beam synchronous femtosecond laser slicing and automatic peeling device includes: Femtosecond laser source module: used to generate a single-channel femtosecond laser; Multi-beam femtosecond laser stenographic module: includes a spatial light modulator, a beam splitter prism group and a beam scanning control unit arranged sequentially along the optical path; A single laser beam is split into multiple parallel sub-beams using a spatial light modulator and a beam splitter prism group. The beam scanning control unit is used to drive the multiple sub-beams to perform radial synchronous scanning along multiple preset concentric ring paths on the same focal plane inside the ingot, so as to form a continuous annular modified layer at the target depth within a single processing cycle. Infrared rapid heating automatic stripping module: includes an infrared heating array, a temperature field monitoring unit, and a heating power controller disposed on the back side of the crystal ingot relative to the hidden cut surface; After the hidden cutting process is completed, the infrared heating array is used to apply a spatially controllable rapid thermal shock to the back side of the ingot, and to induce a transient temperature gradient field between the hidden cutting modified region and the unmodified region of the ingot. By utilizing the difference in thermal expansion coefficients between the hidden modified region and the unmodified region, concentrated thermal stress is generated at the modified layer, causing the wafer to be automatically peeled off along the annular modified layer.

[0007] The spatial light modulator is a phase-type liquid crystal spatial light modulator, which is used to dynamically modulate the wavefront of the incident laser to correct aberrations and optimize the light field distribution. The beam-splitting prism group is located after the spatial light modulator and is a diffractive optical element or a combination of polyhedral prisms, used to split the modulated laser beam into multiple parallel sub-beams. The beam splitter prism group is configured to divide the modulated single-path laser beam into 4 to 8 parallel sub-beams, enabling the multi-beam femtosecond laser stencil module to simultaneously process multiple annular regions, thereby improving the stencil processing efficiency.

[0008] The infrared heating array is composed of mid-wave infrared lamps, whose emission wavelength matches the absorption peak of SiC material in the corresponding band, for efficient and selective input of thermal energy into the ingot.

[0009] The heating power controller is electrically connected to the infrared heating array and the temperature field monitoring unit, and is configured to perform zoned regulation of heating power based on real-time temperature distribution data through a closed-loop control algorithm, so as to generate a transient temperature gradient field with a gradient value range between 150℃ / mm and 300℃ / mm near the interface of the hidden modified layer.

[0010] It also includes a vision-guided automatic wafer pickup and transfer module, which includes a machine vision locator and a robotic arm with a flexible adsorption gripper at its end; the adsorption surface of the flexible adsorption gripper is made of porous material and the wafer is adsorbed by a controllable vacuum negative pressure. It is used to identify the position of the wafer in real time after it is peeled off, and to control the robotic arm to perform non-contact picking and smooth transfer.

[0011] It also includes a digital twin monitoring platform, which includes a 3D model construction module, a multi-sensor data fusion module, and a visual human-machine interface, capable of displaying in real time the hidden-cut scanning path, the 3D morphology of the modified layer, the temperature field distribution of the ingot, the thermal stress evolution process, and the movement trajectory of the robotic arm.

[0012] An integrated multi-beam synchronous femtosecond laser slicing and automatic stripping method includes the following steps: S1: Fixing and leveling the crystal ingot, and loading it into the working position of the device. S2: Activate the multi-beam femtosecond laser hidden cutting module to control multiple femtosecond laser sub-beams to synchronously scan along multiple concentric circular paths at a predetermined depth inside the ingot, forming a continuous annular modified layer; the synchronous scanning is radial synchronous scanning, and the multiple sub-beams move synchronously along circular rings of different radii on the focal plane under the control of the scanning galvanometer. S3: After the hidden cutting is completed, the infrared rapid heating automatic stripping module is started to control the infrared heating unit to form a controllable temperature gradient field on the back of the ingot, and induce thermal stress to automatically separate the wafer along the modified layer; the establishment of the temperature gradient field is achieved by real-time feedback of temperature distribution by an infrared thermometer, and by the heating power controller dynamically adjusting the power of the lamps in different areas of the infrared lamp array. S4: After the stripping is completed, the vision-guided automatic wafer picking and transfer module is activated. The separated wafers are located by machine vision, and the robotic arm and flexible adsorption fixture are controlled to pick up the wafers and transfer them to the designated container. S5: Monitor and record the process data of the entire process from step S2 to step S4 in real time through the digital twin monitoring platform.

[0013] The technical effects achieved by this invention are as follows: This invention introduces a core design of spatial light modulator and beam-splitting prism group to modulate and split a single femtosecond laser into multiple parallel sub-beams. These beams are driven by a beam scanning control unit to synchronously perform multi-ring scanning within the ingot, achieving a processing mode shift from "single-point serial" to "multi-point parallel." This design significantly increases the modified area covered in a single processing cycle, effectively solving the fundamental contradiction of long hidden cutting paths and time consumption in large-size wafers. It effectively shortens the hidden cutting time compared to traditional single-beam scanning technology, laying a crucial foundation for femtosecond laser hidden cutting technology to move towards high-throughput, low-cost industrial production.

[0014] This invention abandons the traditional mechanical pin-based force-based peeling method and innovatively adopts infrared rapid heating-induced thermal stress peeling technology. By precisely controlling the mid-wave infrared lamp array, a high-intensity and gradient-controllable transient temperature field is constructed on the back of the ingot. This technology utilizes the inherent difference in the coefficient of thermal expansion between the hidden-cut modified layer and the original material to generate highly concentrated pure thermal stress at a predetermined interface. This stress acts gently and uniformly on the entire annular modified layer, driving cracks to smoothly propagate "from the inside out" along the preset vulnerable surface, thereby achieving clean, intact, and natural separation of the wafer. This method completely avoids the stress concentration, fragment sputtering, and latent microcrack problems caused by mechanical impact. The peeled surface is flat and smooth, and the bending strength and electrical performance consistency of the substrate are significantly improved.

[0015] This invention organically integrates the three core processes of "hidden cutting," "peeling," and "pick-up and transfer" into a single device, and coordinates them through a unified central control system. Under the scheduling of the digital twin platform, the actions of each module are precisely linked in sequence, forming a complete unmanned operation closed loop. In particular, the vision-guided robotic arm and flexible adsorption gripper enable non-contact, high-precision automatic picking and placing of the wafers after peeling, eliminating the risks of contamination, scratches, and wafer breakage caused by manual operation. This highly integrated design not only significantly reduces the turnaround time and floor space between processes, but also fundamentally ensures the stability and repeatability of the process by reducing human intervention, providing a final solution for building standardized, unmanned intelligent production lines. Attached Figure Description

[0016] Figure 1 This is a block diagram of the device of the present invention; Figure 2 This is a flowchart of the method of the present invention. Detailed Implementation

[0017] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.

[0018] like Figure 1 As shown, the integrated multi-beam synchronous femtosecond laser slicing and automatic peeling device includes: Femtosecond laser source module: Used to generate a single-channel femtosecond laser as the energy source for hidden cutting; the output pulse width of this source can be adjusted in the range of 50-200fs, the repetition frequency is 100-500kHz, the center wavelength is 1030nm, and the laser power adjustment range is 2-5W, ensuring that stable and controllable laser energy is provided for hidden cutting. Multi-beam femtosecond laser stenography module: including a spatial light modulator, a beam splitter prism group and a beam scanning control unit arranged sequentially along the optical path, is the core module for realizing multi-beam synchronous stenography; The spatial light modulator uses a phase-type liquid crystal spatial light modulator, which dynamically controls the wavefront of the incident laser by loading a specific phase diagram, providing a uniform light field distribution for subsequent beam splitting; the beam splitting prism group uses diffractive optical elements or a combination of polyhedral prisms, which are set after the spatial light modulator, and can stably split the modulated single laser beam into 4-8 parallel sub-beams, effectively increasing the coverage area of ​​a single processing. The beam scanning control unit consists of a two-dimensional scanning galvanometer and a focus positioning unit. The scanning range of the two-dimensional scanning galvanometer is 0-300mm×300mm, and the scanning accuracy is 0.1μm. The focus positioning unit adopts piezoelectric ceramic drive and has a positioning accuracy of ±1μm. It is used to drive multiple sub-beams to perform radial synchronous scanning on the same focal plane inside the ingot along multiple preset concentric ring paths, ensuring that a continuous and uniform annular modified layer is formed at the target depth within a single processing cycle. The spatial light modulator and beam-splitting prism group in the multi-beam femtosecond laser stencil module constitute a collaborative beam-splitting system. The spatial light modulator modulates the wavefront of the incident single-path femtosecond laser beam by loading a dynamic phase map, primarily achieving two functions: first, correcting aberrations in the optical system to ensure the quality of subsequent beams; and second, homogenizing the light intensity distribution to provide a uniform and stable input light field for beam splitting. The modulated laser beam is then incident on the beam-splitting prism group. The beam-splitting prism group is a fixed optical element that, based on the microstructure of diffractive optical elements or the design of the reflective / refracting surfaces of polyhedral prisms, physically divides the incident homogenized laser beam into multiple spatially parallel, uniformly energetic sub-beams. This collaborative design combines the flexibility of dynamic control of the spatial light modulator with the high efficiency and stability of the fixed beam-splitting element, making it crucial for achieving high-quality, high-efficiency multi-beam parallel processing. Infrared rapid heating automatic peeling module: includes an infrared heating array, a temperature field monitoring unit and a heating power controller set on the back side of the ingot relative to the hidden surface, for realizing automatic and non-destructive peeling of the wafer; The infrared heating array is composed of mid-wave infrared lamps, whose emission wavelength matches the absorption peak of SiC material in the corresponding band, ensuring that heat is efficiently absorbed by the ingot; the temperature field monitoring unit uses an infrared thermometer with a temperature measurement accuracy of ±2℃, which can collect temperature distribution data of the ingot surface and interior in real time. The heating power controller is connected to the infrared heating array and the temperature field monitoring unit. It dynamically adjusts the heating power through a PID closed-loop control algorithm to form a transient temperature gradient field with a gradient value of 150℃ / mm-300℃ / mm between the hidden modified region and the unmodified region of the ingot. It utilizes the difference in the thermal expansion coefficients of the two types of regions to generate concentrated thermal stress, which causes the wafer to naturally fracture and separate along the annular modified layer.

[0019] The vision-guided automated wafer picking and transfer module includes a machine vision locator and a robotic arm with a flexible adsorption gripper at the end, enabling automated picking and transfer of wafers after stripping. The machine vision positioner consists of a high-definition industrial camera and an image recognition algorithm, which can identify the position of the separated wafers in real time with a positioning accuracy of ±5μm; the flexible adsorption fixture uses porous ceramic material for its adsorption surface, and adsorbs the wafers through controllable vacuum negative pressure, avoiding the scratches on the wafer surface caused by traditional mechanical clamping. The robotic arm has a motion repeatability accuracy of ±0.01mm, enabling it to perform smooth, non-contact pick-up and transfer operations, accurately transferring wafers to the cleaning tray.

[0020] Digital twin monitoring platform: includes a 3D model building module, a multi-sensor data fusion module, and a visual human-machine interface, to realize digital monitoring and traceability of the entire processing process; The 3D model building module constructs a digital twin of the crystal ingot processing based on the CAD model of the crystal ingot and real-time processing data; the multi-sensor data fusion module integrates beam scanning data, modified layer detection data, temperature field data, stress evolution data and robotic arm motion data to achieve synchronization and fusion of multi-source data; The visual human-machine interface can display the hidden scanning path, the three-dimensional morphology of the modified layer, the temperature field distribution of the ingot, the thermal stress evolution process, and the movement trajectory of the robotic arm in real time. It also supports historical query of process parameters, fault diagnosis, and remote control functions.

[0021] Central control system: It adopts a PLC controller combined with an industrial computer as the "brain" of the entire device, connecting and controlling all the above modules; The PLC controller is responsible for the real-time action control of each module, with a response time of less than 1ms. The industrial computer runs dedicated control software to realize the setting of processing parameters, automated process control of the processing, real-time data acquisition and analysis, and human-machine interaction functions. The control system is equipped with a 15-inch touch screen, which can intuitively display the processing status and detection data, and is easy to operate.

[0022] like Figure 1 As shown, the integrated multi-beam synchronous femtosecond laser stenography and automatic stripping method includes the following steps: S1: Ingot fixing and leveling. Select an n-type or p-type SiC single crystal ingot. First, use ultrasonic cleaning technology to clean the surface of the ingot in sequence with acetone, ethanol and deionized water for 10-15 minutes each to remove surface oil and impurities. Then, load the ingot onto the vacuum adsorption worktable, start the precision leveling mechanism and flatness detection unit, and adjust it with three-point support to make the flatness error of the upper surface of the ingot less than 0.5μm, completing the pre-processing preparation. S2: Start the multi-beam femtosecond laser hidden cutting module. According to the target peeling thickness, set the femtosecond laser parameters through the central control system: laser power 2-5W, scanning speed 300-800mm / s, scanning spacing 0.5-1μm. The focus positioning unit accurately positions the focus of each sub-beam at the distance from the target thickness on the upper surface inside the crystal ingot. After the parameters are set, the central control system starts the femtosecond laser source; the generated single-path femtosecond laser is first incident on the phase-type liquid crystal spatial light modulator; the spatial light modulator dynamically modulates the laser wavefront according to a pre-calculated and loaded specific phase diagram; the core purpose of this modulation process is to correct the system aberrations in the optical path and optimize the intensity distribution of the beam so that it obtains a more uniform and sharper focus at the target focal plane, rather than directly splitting the beam; The laser beam, modulated and homogenized by a spatial light modulator, is then transmitted to a beam-splitting prism group. In this embodiment, the beam-splitting prism group employs a custom-designed diffractive optical element. This diffractive optical element, through its micro-nano structure, efficiently diffracts the incident single homogenized laser beam into multiple sub-beams with specific deflection angles. These sub-beams are then converted into multiple processing focal points that are spatially parallel and precisely converged on the same focal plane inside the ingot through a shared collimating / focusing optical system. The beam scanning control unit, which includes a two-dimensional scanning galvanometer and a focus positioning unit, receives instructions from the central control system and drives the multiple parallel beams to focus on the focal plane and perform synchronous scanning along multiple preset concentric circular paths, thereby forming a continuous annular modified layer inside the ingot. S3: After the hidden cutting is completed, the central control system activates the infrared rapid heating automatic stripping module; the infrared heating array (aimed at the back of the ingot, the side opposite the hidden cutting surface) applies a rapid thermal shock that can be precisely programmed in both time and space. A high power rate is used in the initial heating stage to rapidly raise the temperature of the back of the ingot; The temperature field monitoring unit integrated near the heating area is immediately activated, and collects and feeds back the three-dimensional temperature distribution data of the entire back of the crystal ingot and even the internal three-dimensional temperature estimated by the model in real time with a millisecond response speed; this data is transmitted to the heating power controller in real time. The heating power controller dynamically and independently adjusts the output power of lamps in different annular regions or sectors of the infrared lamp array based on a preset peeling stress model and target temperature gradient values ​​of 150℃ / mm-300℃ / mm. Its core objective is to actively construct and maintain a steep and controllable transient temperature gradient field between the wafer region containing the annular hidden-cut modified layer and the unmodified region of the underlying ingot matrix. Due to its structural changes, the modified layer exhibits significant differences in thermal expansion coefficient and thermal conductivity compared to the original material. Due to the differential thermal expansion of the two regions under the same heat input, huge localized thermal stress is generated inside the constrained ingot. This stress is highly concentrated in the annular modified layer where the mechanical strength has been weakened by the laser. When the thermal stress exceeds the material bonding strength at the modified layer, cracks preferentially and rapidly and controllably initiate and propagate along the modified layer, ultimately driving the wafer to achieve clean and complete natural separation along the preset hidden cutting path. During this process, a high-speed camera observes and records the entire process of crack initiation and propagation in real time at a rate of 1,000 to 5,000 frames per second. This system is not only used to verify whether the peeling is carried out along the predetermined modified layer, but also to evaluate the flatness and quality of the peeling surface through image analysis, providing direct visual evidence for process optimization and ensuring that the peeling results meet the requirements of subsequent processes. S4: After the stripping is completed, the vision-guided automatic wafer picking and transfer module is activated; the machine vision locator captures and identifies the position of the separated wafer and transmits the positioning data to the central control system; the control system controls the robotic arm to move the flexible adsorption fixture above the wafer, and starts adsorption through controllable vacuum negative pressure to achieve non-contact picking; then the robotic arm moves smoothly along the preset path to transfer the wafer to the cleaning tray, and releases the vacuum after completion to remove the wafer. S5: Throughout the entire process from step S2 to step S4, the digital twin monitoring platform synchronizes multi-sensor data in real time, dynamically displaying the hidden-cut scanning path, the three-dimensional morphology of the modified layer, the temperature field distribution of the ingot, the thermal stress evolution process, and the movement trajectory of the robotic arm on the visualization interface. At the same time, it automatically records process information such as laser parameters, processing time, temperature data, and peeling status, forming a complete process archive to support subsequent remote diagnosis and process traceability.

[0023] Example 1 A 500μm thick substrate was prepared by exfoliation from a 4-inch n-type 4H-SiC ingot. Device preparation: The integrated device as described in the invention is ready; S1: Select an n-type 4H-SiC crystal ingot with a diameter of 4 inches and a length of 100 mm; perform ultrasonic cleaning with acetone, ethanol and deionized water for 12 minutes each in sequence; after drying, load it onto the vacuum adsorption stage of the device; start the precision leveling mechanism and adjust it through three-point support to make the flatness error of the upper surface of the crystal ingot <0.3 μm; S2: Parameter settings: Set via the central control system: femtosecond laser pulse width 100 fs, repetition frequency 300 kHz, power 3 W; target ablation thickness 500 μm; scanning speed 500 mm / s, scanning spacing 0.8 μm, scanning overlap rate 60%; Beam generation and calibration: A femtosecond laser source emits a single laser beam; The spatial light modulator loads a composite phase map calculated based on system aberrations and beam splitting requirements to pre-shape and homogenize the laser wavefront; The shaped laser beam is incident on the beam-splitting prism group, and the diffractive optical elements efficiently split the incident light into multiple designed diffraction orders; After being split, the multi-path diffracted light passes through a common collimating lens group and is finally output as 6 femtosecond laser sub-beams that are spatially parallel and have energy uniformity >95%. The beam diagnostic unit calibrates the pointing and spot quality of the six sub-beams to ensure that they can be accurately focused on the same focal plane. Synchronous scanning processing: The piezoelectric ceramic focus positioning unit precisely sets the focus of 6 beams of light inside the ingot at a distance of 500μm from the upper surface; The path planner of the central control system generates a virtual multi-ring scanning template covering the entire wafer area based on the ingot diameter and the target wafer thickness, which contains 6 concentric ring paths. The beam scanning control unit receives instructions and drives six parallel beams to synchronously perform a spiral scan on the focal plane. Each beam is responsible for a ring area of ​​a specific radius. During the processing, the laser reflection / transmission detector monitors the signal in real time. When the system determines that the continuity of the ring-shaped modified layer reaches 96%, it automatically stops the laser output. The total processing time is 3.2 minutes. S3: After the hidden cutting is completed, the worktable will automatically rotate or translate so that the hidden cutting surface of the ingot is aligned with the mid-wave infrared lamp array above. The central control system initiates the stripping process; the infrared lamp array is illuminated in sections, and high power is initially used to rapidly heat the central area on the back of the ingot. An infrared thermometer scans the temperature distribution on the back of the crystal ingot in real time at a frequency of 100Hz, and the data is fed back to the heating power controller. The controller performs PID calculations based on a preset model, with a target gradient of 200°C / mm, and dynamically adjusts the power of different regions of the array: making the temperature of the region above the corresponding hidden modified layer higher, while the temperature of the parent body region below is lower, thereby establishing a precisely controlled steep temperature gradient at the interface of the modified layer. Under thermal stress, after about 15 seconds, the cracks started from the modified layer at the edge of the ingot and quickly and smoothly expanded along the entire annular modified layer, and the wafers were automatically separated. The bypass high-speed camera recorded the entire stripping process at a shooting speed of 3000 frames per second. Image analysis showed that the stripping proceeded along the predetermined interface, and the process was smooth with no debris splashing. S4: At the moment the separation is completed, the industrial camera of the machine vision system captures an image of the stage and accurately identifies the center position and attitude angle of the separated wafer through an image recognition algorithm, with a positioning accuracy of ±10μm. The central control system sends the pose data to the six-axis robotic arm; the robotic arm moves the flexible porous ceramic adsorption gripper at the end to directly above the wafer; the gripper descends to a non-contact height, and a controllable vacuum negative pressure is activated to steadily adsorb the wafer; the robotic arm smoothly lifts and moves, accurately placing the wafer into a pre-set cleaning tray, and then the vacuum is turned off to complete the transfer; S5: Throughout the entire process from steps S2 to S4, the digital twin monitoring platform operates synchronously. The three-dimensional view on the left side of the interface displays in real time: the scanning path highlights of the 6 laser beams, the semi-transparent rendering model of the annular modified layer inside the crystal ingot, the pseudo-color temperature cloud map on the back of the crystal ingot, and the thermal stress vector distribution. The right panel of the interface displays key parameters such as real-time power of each beam, scanning progress, temperature gradient curve, peeling status, and robotic arm coordinates. All process parameters, sensor data, and timestamps are automatically recorded and stored in the database, forming a complete "processing passport" for the wafer, which can be accessed and traced at any time. Post-processing and inspection: The cleaning tray carrying the wafer was transferred to a separate cleaning station for plasma cleaning for 8 minutes; then the following tests were performed: the surface roughness Ra was measured to be 0.28 μm by atomic force microscopy; the thickness uniformity TTV was measured to be 1.2 μm by laser interferometer.

[0024] Example 2 6-inch n-type 4H-SiC ingot, peeling to prepare 150μm ultrathin wafers S1: Select an n-type 4H-SiC ingot with a diameter of 6 inches and a length of 125 mm; adopt the same ultrasonic cleaning process as in Example 1; use a vacuum adsorption stage extended to 6 inches and a higher precision flatness detection unit, and level it with five-point support to ensure that the flatness error of the upper surface is <0.2 μm; S2: Parameter settings: Set via the central control system: femtosecond laser pulse width 50 fs, repetition frequency 500 kHz, power 2.2 W; target ablation thickness 150 μm, scanning speed 300 mm / s, scanning spacing 0.5 μm, scanning overlap rate 65%; Beam generation and calibration: To cover a larger processing area, the system is configured with a beam splitter prism group to output 8 parallel sub-beams; the spatial light modulator is loaded with a phase map optimized for ultra-thin refining, and the energy uniformity of each sub-beam after beam splitting is >98%; the beam diagnostic unit performs nanometer-precision pointing calibration. Synchronous scanning processing: The piezoelectric ceramic focus positioning unit precisely sets the focus of 8 beams of light at a depth of 150μm from the surface of the ingot; the path planner generates a spiral scanning template with 8 concentric rings, and the spacing between the rings is optimized to match the stress distribution of the ultrathin layer; during processing, the sensitivity of the laser reflection / transmission detector is increased, signal fluctuations are monitored in real time, and the power is dynamically fine-tuned to maintain the uniformity of the modified layer; the system automatically stops when it determines that the continuity of the annular modified layer reaches 98%; the total processing time is 8.5 minutes. S3: After the hidden dicing is completed, the infrared heating array is activated; to address the characteristics of ultra-thin wafers being prone to warping and breakage, a "two-step" heating strategy is adopted: An infrared lamp array heats the entire back of the ingot to 150°C with low power, releasing some internal stress and reducing thermal shock. The heating power controller sets the target temperature gradient to 150°C / mm based on the preset "ultra-thin wafer peeling model"; the infrared lamp array switches to a multi-region independent control mode to accurately build the required temperature gradient field near the modified layer. Under precisely controlled thermal stress, the cracks started from the center of the ingot and spread steadily outwards at a speed of about 1-2 m / s. After about 25 seconds, the entire 150 μm thick wafer was completely peeled off. A high-speed camera observed and confirmed that the cracks spread completely along the modified layer without any branches or skipping layers. S4: Given the extreme fragility of ultra-thin wafers, the machine vision positioner uses a multi-angle camera array to identify potential micro-warping poses with an accuracy of ±3μm; the vacuum negative pressure of the flexible adsorption fixture is precisely calibrated, and a "stepped" adsorption strategy is adopted: first, contact is made with an extremely low negative pressure, and after confirming that the adsorption is stable, it is slowly increased to the working negative pressure; the six-axis robotic arm operates in a low-speed, high-acceleration smooth mode to smoothly transfer the wafer to a specially designed support cleaning tray with extremely high flatness; S5: During the processing, the digital twin platform highlights the three-dimensional morphology of the ultrathin modified layer and calculates and warns of potential stress concentration areas in real time; the thermal stress evolution process is displayed in slow animation form, which makes it easy to observe the crack initiation and propagation behavior; all process data are recorded to form an "ultrathin wafer process archive". Post-processing and inspection: The transferred wafers are subjected to low-temperature plasma cleaning; Test results: The surface roughness Ra was measured to be 0.15 nm using atomic force microscopy. The thickness uniformity TTV was measured to be 0.8 μm using a laser interferometer. Micro Raman spectroscopy revealed no obvious residual stress peaks, indicating that the peeling process did not introduce additional damage.

[0025] Example 3 Fabrication of 2-inch GaN self-supporting substrate S1: Select a 2-inch diameter GaN ingot with c-face; change the cleaning process to use a gentler organic solvent and deionized water for GaN; due to its small size, use a high-rigidity fixture for fixation, and adjust the flatness to <0.5μm; S2: Parameter settings: GaN has a different bandgap and thermodynamic properties than SiC; laser parameters are adjusted as follows: pulse width 150fs, repetition frequency 200kHz, center wavelength still 1030nm, power 3.5W; target ablation thickness 400μm; scanning speed 400mm / s, scanning spacing 0.7μm; Beam generation and calibration: A spatial light modulator is loaded with a phase map optimized for the nonlinear absorption characteristics of GaN material; a beam splitter prism group outputs four sub-beams; the calibration process focuses on spherical aberration compensation at the focal point inside GaN. Synchronous scanning processing: The focal point is positioned at a depth of 400 μm; the scanning path adopts a composite path combining a checkerboard pattern and concentric rings to better adapt to the anisotropy of GaN; during the processing, the quality of the modified layer is indirectly judged by monitoring the plasma emission spectrum; the process is stopped when the continuity of the modified layer meets the standard. S3: GaN has high transparency in some infrared bands, so the wavelength of the infrared heating array is optimized for the absorption characteristics of GaN (e.g., using LED arrays or laser diode arrays in specific bands) to ensure that energy is efficiently absorbed by the modified layer region. The heating strategy emphasizes "rapid pulse heating" to quickly establish the required thermal stress before the brittleness of GaN causes uncontrollable crack propagation; the target temperature gradient is set at 250°C / mm; the temperature field monitoring unit needs to be able to penetrate GaN to measure the temperature to a certain depth; Under thermal shock, GaN wafers are peeled off along the modified layer; due to their higher fracture toughness, the peeling sound is crisper than that of SiC, and the crack propagation speed is observed to be faster by high-speed cameras. S4 / S5: Picking and Monitoring The pick-up and transfer process is the same as in Example 1, but considering the value of GaN, the transfer environment needs to maintain a higher level of cleanliness; the digital twin platform integrates the GaN material database, and the stress evolution model it displays is calculated based on the mechanical parameters of GaN; Post-processing and inspection: The wafer undergoes chemical mechanical polishing to remove an extremely thin layer of modified material. Test results: The initial roughness Ra of the peeled surface was measured to be less than 1 nm using a white light interferometer. High-resolution X-ray diffraction revealed that the half-width at half-maximum (FWHM) of the wafer's surface rocking curve was 35 arcseconds, indicating that the wafer had extremely high crystal quality and that the peeling process did not introduce serious lattice damage.

[0026] In summary, the "integrated multi-beam synchronous femtosecond laser slicing and automatic stripping device" can achieve efficient, high-precision, and low-damage processing in the fabrication of advanced semiconductor wafers of different sizes, thicknesses, and materials, demonstrating strong process adaptability and broad application prospects.

[0027] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. An integrated multi-beam synchronous femtosecond laser slicing and automatic peeling device, characterized in that, include: Femtosecond laser source module: used to generate a single-channel femtosecond laser; Multi-beam femtosecond laser stenographic module: includes a spatial light modulator, a beam splitter prism group and a beam scanning control unit arranged sequentially along the optical path; A single laser beam is split into multiple parallel sub-beams using a spatial light modulator and a beam splitter prism group. The beam scanning control unit is used to drive the multiple sub-beams to perform radial synchronous scanning along multiple preset concentric ring paths on the same focal plane inside the ingot, so as to form a continuous annular modified layer at the target depth within a single processing cycle. Infrared rapid heating automatic stripping module: includes an infrared heating array, a temperature field monitoring unit, and a heating power controller disposed on the back side of the crystal ingot relative to the hidden cut surface; After the hidden cutting process is completed, the infrared heating array is used to apply a spatially controllable rapid thermal shock to the back side of the ingot, and to induce a transient temperature gradient field between the hidden cutting modified region and the unmodified region of the ingot. By utilizing the difference in thermal expansion coefficients between the hidden-cut modified region and the unmodified region, concentrated thermal stress is generated at the annular modified layer, causing the wafer to be automatically peeled off along the annular modified layer.

2. The apparatus according to claim 1, characterized in that: The spatial light modulator is a phase-type liquid crystal spatial light modulator, which is used to dynamically modulate the wavefront of the incident laser to correct aberrations and optimize the light field distribution. The beam-splitting prism group is positioned after the spatial light modulator and is a diffractive optical element or a combination of polyhedral prisms, used to split the modulated laser beam into multiple parallel sub-beams.

3. The apparatus according to claim 1, characterized in that: The beam-splitting prism group is used to divide a single laser beam into 4 to 8 parallel sub-beams, enabling the multi-beam femtosecond laser stencil module to simultaneously process multiple annular regions.

4. The apparatus according to claim 1, characterized in that: The infrared heating array is composed of mid-wave infrared lamps, whose emission wavelength matches the absorption peak of SiC material in the corresponding band, for efficient and selective input of thermal energy into the ingot.

5. The apparatus according to claim 1, characterized in that: The heating power controller is electrically connected to the infrared heating array and the temperature field monitoring unit, and is configured to perform zoned regulation of heating power based on real-time temperature distribution data through a closed-loop control algorithm, so as to generate a transient temperature gradient field with a gradient value range between 150℃ / mm and 300℃ / mm near the interface of the hidden modified layer.

6. The apparatus according to claim 1, characterized in that: It also includes a vision-guided automatic chip picking and transfer module, which includes a machine vision locator and a robotic arm with a flexible adsorption gripper at its end. The machine vision locator is used to identify the wafer's pose in real time after it is peeled off. The flexible adsorption clamp uses a porous material for its adsorption surface, and adsorbs wafers through a controllable vacuum negative pressure. The robotic arm is used to control the flexible adsorption gripper to perform non-contact picking and smooth transfer based on the identified pose.

7. The apparatus according to claim 1, characterized in that: It also includes a digital twin monitoring platform, which comprises a 3D model building module, a multi-sensor data fusion module, and a visual human-machine interface; The platform can display the hidden scanning path, the three-dimensional morphology of the modified layer, the temperature field distribution of the ingot, the thermal stress evolution process, and the movement trajectory of the robotic arm in real time, and record the process data.

8. An integrated multi-beam synchronous femtosecond laser slicing and automatic stripping method, using the apparatus described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Fixing and leveling the crystal ingot, and loading it into the working position of the device; S2: Activate the multi-beam femtosecond laser hidden cutting module to control multiple femtosecond laser sub-beams to scan synchronously along multiple concentric circular paths at a predetermined depth inside the ingot, forming a continuous annular modified layer; S3: After the hidden cutting is completed, the infrared rapid heating automatic stripping module is activated to control the infrared heating unit to form a controllable temperature gradient field on the back of the ingot, inducing thermal stress to cause the wafer to automatically separate along the modified layer. S4: After the stripping is completed, the vision-guided automatic wafer picking and transfer module is activated. The separated wafers are located by machine vision, and the robotic arm and flexible adsorption fixture are controlled to pick up the wafers and transfer them to the designated container. S5: Monitor and record the process data of the entire process from step S2 to step S4 in real time through the digital twin monitoring platform.

9. The integrated multi-beam synchronous femtosecond laser slicing and automatic peeling device according to claim 8, characterized in that: In step S2, the synchronous scanning is radial synchronous scanning, and the multiple sub-beams move synchronously along different radius rings on the focal plane under the control of the scanning galvanometer.

10. The integrated multi-beam synchronous femtosecond laser slicing and automatic stripping device according to claim 8, characterized in that: In step S3, the establishment of the temperature gradient field is achieved by real-time feedback of temperature distribution from an infrared thermometer and dynamic adjustment of the power of lamps in different areas of the infrared lamp array by a heating power controller.

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