Method for multi-sequential exfoliation of silicon carbide ingot based on scattering suppression and thermal stress

Abstract

This invention discloses a method for continuous multi-wafer peeling of silicon carbide ingots based on scattering suppression and thermal stress, belonging to the field of semiconductor material laser processing technology. This method uses an ultrashort pulse laser to scan and construct weak bonding interfaces inside the ingot, utilizing thermal stress generated by the temperature gradient to drive crack propagation in a directional manner, thus achieving single-wafer peeling. In particular, it eliminates the need for intermediate grinding and polishing of the rough end face of the ingot during continuous peeling. A high-refractive-index liquid is dropped onto the rough peeling surface, achieving optical planarization and refractive index matching through the fluid physics filling effect, suppressing laser scattering from the rough surface. Combined with a refractive index compensation continuous scanning strategy, the laser is precisely focused deep within the ingot to construct new weak bonding interfaces, cyclically achieving continuous multi-wafer peeling. This invention effectively solves the problems of interruption and low efficiency in existing processes, significantly improving the processing efficiency and peeling yield of silicon carbide wafers.

Description

Technical Field

[0001] This invention belongs to the field of laser processing technology for semiconductor materials, specifically relating to a method for continuous multi-wafer peeling of silicon carbide ingots based on scattering suppression and thermal stress. Background Technology

[0002] As a core representative of third-generation wide-bandgap semiconductors, silicon carbide (SiC) has irreplaceable application value in fields such as new energy vehicles, photovoltaic inverters, and high-frequency high-power electronic devices due to its excellent thermal conductivity, high breakdown electric field, and wide bandgap characteristics. However, silicon carbide is a typical hard and brittle material with a high Mohs hardness. Traditional diamond multi-wire cutting technology faces problems such as large kerf loss, low processing efficiency, and severe tool wear, resulting in high manufacturing costs for silicon carbide wafers.

[0003] In recent years, non-contact internal modification and exfoliation technology, represented by ultrashort pulse lasers, has gradually become an important direction in the evolution of silicon carbide ingot slicing technology. The core principle of this technology is to focus an ultrashort pulse laser at a predetermined depth inside the ingot, inducing local phase transformation and microcrack initiation through multiphoton absorption effects. This constructs a weakly bonded interface interwoven with phase transformation regions and microcracks. Then, a temperature gradient or mechanical stress is applied to drive the cracks to propagate directionally along the interface, achieving the exfoliation of a single wafer. This technology results in minimal kerf loss and significantly improves the utilization rate of ingot materials.

[0004] However, existing laser ablation technology has a key bottleneck: the physical mechanism based on microcrack cleavage inevitably leads to the exposure of micron-scale roughened morphology on the surface of the newly formed ingot after ablation. For subsequent laser beams intended for continuous multi-piece processing, this rough morphology acts as a strong disordered optical scattering interface, causing severe wavefront distortion and focal energy dissipation, making it difficult for the laser to achieve precise secondary focusing and modification within the ingot.

[0005] To overcome this problem, the current industry-standard solution is to interrupt the laser processing flow after each single-piece peeling and switch to a mechanical grinding and polishing process to eliminate surface micro-irritations and restore optical smoothness. This discrete combination process not only significantly reduces overall production efficiency due to the time-consuming physical grinding, but also increases the risk of secondary alignment errors due to repeated clamping and alignment between different processes, while also increasing the complexity of the equipment and maintenance costs.

[0006] Therefore, how to break through the technical bottleneck between "rough surface scattering effect" and "continuous deep focusing" and achieve continuous and low optical path loss multi-layer laser lift-off without relying on cumbersome and time-consuming intermediate grinding and polishing processes is a process problem that urgently needs to be solved in the current semiconductor substrate manufacturing field. Summary of the Invention

[0007] To address the aforementioned issues, this invention proposes a multi-wafer continuous peeling method for silicon carbide ingots based on scattering suppression and thermal stress. This method can solve the problems of beam scattering, energy loss, and inability to process continuously caused by the rough peeling surface in existing laser peeling technologies, significantly improving the manufacturing efficiency and yield of silicon carbide wafers.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A method for continuous multi-wafer peeling of silicon carbide ingots based on scattering suppression and thermal stress includes the following steps: S1. Focus an ultrashort pulse laser to a predetermined depth inside a silicon carbide ingot and perform scanning modification along a set trajectory to construct a weak bonding interface inside the crystal. S2. By applying a differential thermal field to both sides of the weak bonding interface through temperature gradient-induced peeling treatment, a temperature gradient is formed near the weak bonding interface and thermal stress is generated by applying a low temperature to one end of the silicon carbide ingot and a controlled high temperature to the other end. This causes the material to undergo cleavage fracture along the weak bonding interface to complete the wafer separation. After wafer peeling, the silicon carbide ingot exhibits a rough peeling surface with microscopic uneven features on the separated side. S3. A high refractive index liquid is dropped onto the rough peeling surface of a silicon carbide ingot. The high refractive index liquid is covered on the rough peeling surface by relying on the physical filling effect of the fluid. This is used to suppress the scattering of laser light by the rough peeling surface and achieve optical flattening and refractive index matching of the rough peeling surface. S4. A refractive index compensation continuous scanning strategy is adopted so that the ultrashort pulse laser is refocused on a predetermined depth inside the silicon carbide ingot after passing through the high refractive index liquid for scanning and quality improvement, thereby constructing a new weak bonding interface for the peeling of the next wafer. S5. Repeat steps S2 to S4 to sequentially peel off multiple wafers until all silicon carbide ingots are peeled off.

[0009] Preferably, in step S1, the weakly bonded interface formed consists of periodically alternating modified zones and microcracks.

[0010] Preferably, in steps S1 and S4, the wavelength of the ultrashort pulse laser is 355nm~1064nm, the pulse width is 190fs~15ps, and the single pulse energy is 5μJ~50μJ.

[0011] Preferably, in step S1, the set trajectory is a linear array fed along the [1-100] or [11-20] crystal orientation at a set remodeling scan interval at a predetermined depth; the remodeling scan interval is 30μm~150μm; the predetermined depth is 100μm~600μm below the upper surface of the silicon carbide ingot.

[0012] Preferably, in step S2, the temperature gradient induced stripping process includes applying a low temperature to the wafer side to be stripped, the stripping start end, or the area adjacent to the weak bonding interface of the silicon carbide ingot to form a low-temperature end, while applying a controlled high temperature to the opposite end or the other end of the ingot body to form a high-temperature end, so that a temperature gradient is formed on both sides of the weak bonding interface, and the duration of the temperature gradient is 5s to 600s; wherein, the temperature of the low-temperature end is -196℃ to 25℃, the temperature of the high-temperature end is 200℃ to 300℃, and the temperature of the high-temperature end is lower than the temperature at which the silicon carbide lattice structure changes, causes thermal damage, or reacts chemically with the surrounding medium.

[0013] Preferably, in step S3, the refractive index parameter of the high-refractive-index liquid is matched with the refractive index of the silicon carbide material to minimize Fresnel reflection and optical scattering at the liquid-solid composite interface; the high-refractive-index liquid includes at least one of diiodomethane, glycerol, or laser high-refractive-index matching liquid.

[0014] Preferably, in step S3, after adding high-refractive-index liquid to the rough peeling surface using a dropper, the process further includes: using ultrasonic vibration to assist in liquid phase planarization treatment, so that the high-refractive-index liquid can spread uniformly while filling the micro-uneven structure of the surface, and promote the desorption, coalescence and escape of bubbles inside the high-refractive-index liquid, forming a free liquid phase interface with uniform thickness and an optically flat upper surface; the thickness of the free liquid phase interface is 5μm~100μm; the frequency of the ultrasonic vibration is 20kHz~100kHz, the ultrasonic power is 20W~500W, and the ultrasonic treatment time is 60s~600s.

[0015] Preferably, in step S4, the specific process of the refractive index compensation continuous scanning strategy is as follows: when performing the next internal scanning modification, the focusing depth of the processing laser beam is optically compensated and adjusted according to the refractive index of the high refractive index liquid and the thickness parameters of the free liquid phase interface, so as to ensure that the laser is refocused on the next predetermined depth inside the ingot.

[0016] By adopting the above technical solution, the present invention has the following beneficial effects: 1. This invention uses high-refractive-index liquid-phase planarization technology to replace the traditional solid-phase mechanical grinding and polishing process. After a single piece is peeled off, there is no need to interrupt the processing flow, transfer the workpiece, or repeatedly clamp and align it. Surface optical repair and the next round of laser modification can be completed directly at the same station, forming a closed-loop continuous operation mode of "peeling-planarization-re-peeling". This can greatly improve the overall processing efficiency of silicon carbide ingot slices, while significantly reducing the time loss and labor costs caused by process connection.

[0017] 2. This invention eliminates the diffuse scattering effect of the rough surface by filling the micro-uneven structure of the rough exfoliated surface with a high refractive index liquid that matches the refractive index of silicon carbide. At the same time, it minimizes Fresnel reflection at the liquid-solid interface, which can significantly improve the laser transmittance of the original rough surface. In addition, the optical-grade free liquid phase interface formed by ultrasonic vibration-assisted planarization effectively avoids the wavefront distortion of the incident laser, ensuring the focusing accuracy of the laser in the deep layer of the ingot and the uniformity of the quality of the modified layer. It can effectively suppress laser scattering and ensure focusing accuracy and modification quality.

[0018] 3. The refractive index compensation continuous scanning strategy adopted in this invention can accurately calculate the optical path compensation amount based on the liquid refractive index and liquid layer thickness, automatically adjust the laser focusing depth, offset the focus shift caused by the liquid phase layer, and ensure that the depth accuracy deviation of each scanning modification is controlled within ±2μm. This ensures the consistency of the thickness of each wafer during the continuous peeling process of multiple wafers, effectively reduces the processing defect rate, and improves the product yield.

[0019] 4. This invention uses differentiated thermal field-induced thermal stress to drive crack propagation along the weak bonding interface, which is a purely non-contact peeling method, avoiding the external force impact and edge damage caused by traditional mechanical peeling; at the same time, the temperature at the high-temperature end is strictly controlled to be lower than the silicon carbide lattice damage threshold, so as not to cause thermal damage to the ingot body and the wafer, thus ensuring the material electrical properties and surface integrity of the wafer. Attached Figure Description

[0020] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram illustrating the peeling principle of the present invention; Figure 3 This is a schematic diagram of the optical path in which the rough peeling surface of a silicon carbide ingot causes scattering interference to the subsequent incident laser in the existing technology. Figure 4 This is a schematic diagram of the optical path principle of the present invention, which utilizes a high-refractive-index liquid for optical planarization to eliminate scattering interference. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] like Figures 1 to 4 As shown. A method for continuous multi-wafer peeling of silicon carbide ingots based on scattering suppression and thermal stress, characterized by comprising the following steps: S1. Focus an ultrashort pulse laser to a predetermined depth inside a silicon carbide ingot and perform scanning modification along a set trajectory to construct a weak bonding interface inside the crystal. In step S1, the weakly bonded interface formed consists of periodically alternating modified zones and microcracks. The wavelength of the ultrashort pulse laser is 355nm~1064nm, the pulse width is 190fs~15ps, and the single pulse energy is 5μJ~50μJ; In step S1, the set trajectory is a linear array fed along the [1-100] or [11-20] crystal orientation at a set remodeling scan interval at a predetermined depth; the remodeling scan interval is 30μm~150μm; the predetermined depth is 100μm~600μm below the upper surface of the silicon carbide ingot; S2. By applying a differential thermal field to both sides of the weak bonding interface through temperature gradient-induced peeling treatment, a temperature gradient is formed near the weak bonding interface and thermal stress is generated by applying a low temperature to one end of the silicon carbide ingot and a controlled high temperature to the other end. This causes the material to undergo cleavage fracture along the weak bonding interface to complete the wafer separation. After wafer peeling, the silicon carbide ingot exhibits a rough peeling surface with microscopic uneven features on the separated side. In step S2, the temperature gradient induced stripping process includes applying a low temperature to the wafer side to be stripped, the stripping start end, or the area adjacent to the weak bonding interface of the silicon carbide ingot to form a low temperature end, while applying a controlled high temperature to the opposite end or the other end of the ingot body to form a high temperature end, so that a temperature gradient is formed on both sides of the weak bonding interface, and the duration of the temperature gradient is 5s to 600s; wherein, the temperature of the low temperature end is -196℃ to 25℃, the temperature of the high temperature end is 200℃ to 300℃, and the temperature of the high temperature end is lower than the temperature that causes changes in the silicon carbide lattice structure, thermal damage, or chemical reaction with the surrounding medium; S3. A high refractive index liquid is dropped onto the rough peeling surface of a silicon carbide ingot. The high refractive index liquid is covered on the rough peeling surface by relying on the physical filling effect of the fluid. This is used to suppress the scattering of laser light by the rough peeling surface and achieve optical flattening and refractive index matching of the rough peeling surface. In step S3, the refractive index parameter of the high-refractive-index liquid is matched with the refractive index of the silicon carbide material to minimize Fresnel reflection and optical scattering at the liquid-solid composite interface; the high-refractive-index liquid includes at least one of diiodomethane, glycerol, or laser high-refractive-index matching liquid; In step S3, after adding high-refractive-index liquid to the rough peeling surface using a dropper, the process further includes: using ultrasonic vibration to assist in liquid phase planarization treatment, so that the high-refractive-index liquid can spread uniformly while filling the micro-uneven structure of the surface, and promote the desorption, coalescence and escape of bubbles inside the high-refractive-index liquid, forming a free liquid phase interface with uniform thickness and an optically flat upper surface; the thickness of the free liquid phase interface is 5μm~100μm; the frequency of the ultrasonic vibration is 20kHz~100kHz, the ultrasonic power is 20W~500W, and the ultrasonic treatment time is 60s~600s; S4. A refractive index compensation continuous scanning strategy is adopted so that the ultrashort pulse laser is refocused on a predetermined depth inside the silicon carbide ingot after passing through the high refractive index liquid for scanning and quality improvement, thereby constructing a new weak bonding interface for the peeling of the next wafer. In step S4, the specific process of the refractive index compensation continuous scanning strategy is as follows: when performing the next internal scanning modification, the focusing depth of the processing laser beam is optically compensated and adjusted according to the refractive index of the high refractive index liquid and the thickness parameters of the free liquid phase interface, so as to ensure that the laser is refocused on the next predetermined depth inside the ingot. S5. Repeat steps S2 to S4 to sequentially peel off multiple wafers until all silicon carbide ingots are peeled off.

[0023] The following examples illustrate this in detail: This embodiment uses a 6-inch n-type 4H-SiC ingot as the processing object and implements the multi-wafer continuous peeling method for silicon carbide ingots based on scattering suppression and thermal stress described in this invention. The process flow is as follows: Figure 1 As shown, the specific steps are as follows: S1. Laser internal scanning modification to construct a weak bonding interface; The silicon carbide ingot is fixed to the bottom support area of ​​a dedicated ingot carrier and liquid-containing fixture by vacuum adsorption, and the upper surface of the ingot is adjusted to a horizontal state. The ultrashort pulse laser source is activated, and the output ultrashort pulse laser is shaped and expanded by the beam control and focusing module, and then incident vertically from the upper surface of the ingot. It is precisely focused by the objective lens at a predetermined depth inside the ingot.

[0024] In this embodiment, the wavelength of the ultrashort pulse laser is 1030nm, the pulse width is 190fs, and the single pulse energy is 20μJ; the predetermined depth is set to 250μm below the upper surface of the crystal ingot.

[0025] The ingot is moved by a motion platform, and the laser focus is controlled along the [11-20] crystal orientation of the ingot. A linear array scan is performed at a set modification scan interval, which is 80 μm in this embodiment. During the scan, the silicon carbide material at the laser focus generates high-density plasma through multiphoton absorption, inducing local amorphization modification and microcrack initiation. After the line-by-line scan is completed, a continuous weak bonding interface consisting of periodically alternating modification zones and microcracks is finally formed inside the ingot.

[0026] S2. Temperature gradient-induced peeling completes the separation of single wafers; After the weak bonding interface is constructed, the temperature gradient-induced peeling module is activated to apply differentiated thermal fields to both sides of the weak bonding interface. Specifically, a low temperature is applied to the wafer side of the silicon carbide ingot to be peeled (the area above the weak bonding interface) to form a low-temperature end; a controlled high temperature is applied to the other end of the ingot body (the area below the weak bonding interface) to form a high-temperature end, thereby creating a stable temperature gradient along the thickness direction of the ingot near the weak bonding interface.

[0027] In this embodiment, the low-temperature end temperature is controlled at 25°C and the high-temperature end temperature is controlled at 250°C. This temperature is far below the critical temperature that would cause changes in the silicon carbide lattice structure, thermal damage, or chemical reaction with the surrounding medium, and would not cause irreversible damage to the ingot material. The duration of the temperature gradient is set to 120s.

[0028] Temperature gradients cause differential thermal expansion and contraction of silicon carbide materials on both sides of the weak bonding interface, resulting in tensile and shear stress concentrations at the interface. When the thermal stress exceeds the fracture strength of the weak bonding interface, microcracks initiate from the modified area and propagate and penetrate along the interface, eventually causing the material to undergo cleavage fracture along the weak bonding interface, thus completing the separation of the monolithic wafer.

[0029] After wafer peeling, the separated surface of the remaining silicon carbide ingot exposes microscopic irregularities including modified protrusions and valleys, forming a rough peeling surface with peak-valve heights of approximately 5–10 μm. For example... Figure 3 As shown, the rough peeling surface will cause strong scattering and wavefront distortion of the incident laser in the prior art, resulting in laser energy dissipation and focus shift, making it impossible to achieve subsequent deep focusing processing.

[0030] S3. Add a high-refractive-index liquid to achieve scattering suppression and optical flattening; By eliminating the intermediate grinding and polishing treatment of the rough end face of the ingot during the continuous peeling process, liquid phase optical repair is performed directly on the rough peeled surface at the same station. A high refractive index liquid is quantitatively added to the liquid-containing space of the ingot support and liquid-containing fixture using a dropper, so that the liquid completely floods the rough peeled surface of the ingot.

[0031] In this embodiment, diiodomethane is selected as the high refractive index liquid, which matches the refractive index of silicon carbide material and can effectively minimize Fresnel reflection and optical scattering at the liquid-solid composite interface.

[0032] After the addition is complete, the ultrasonic vibration device integrated at the bottom of the fixture is activated to apply ultrasonic vibration to the fixture and the liquid-containing space, performing ultrasonic-assisted liquid phase leveling treatment. The ultrasonic vibration promotes the full flow of the high-refractive-index liquid, uniformly filling the micro-valve structure of the rough peeling surface, while simultaneously causing the bubbles inside the liquid to desorb, coalesce, and escape upwards to the liquid surface.

[0033] In this embodiment, the ultrasonic vibration frequency is 40kHz, the ultrasonic power is 100W, and the ultrasonic treatment time is 300s. After the treatment, a free liquid phase interface with uniform thickness and optically flat upper surface is formed on the crystal ingot. The thickness of the free liquid phase interface is about 20μm, which is within the preferred range of 5μm to 100μm.

[0034] like Figure 4 As shown, the high refractive index liquid eliminates the unevenness of the rough surface through the physical filling effect. Combined with the refractive index matching effect, it effectively suppresses the scattering effect of the laser on the rough exfoliation surface, so that the surface of the crystal ingot can be restored to the optical conditions that meet the stable incident laser, laying the foundation for subsequent continuous scanning and quality improvement.

[0035] S4. Continuous scanning with refractive index compensation to construct a new weakly bonded interface; A refractive index-compensated continuous scanning strategy is adopted for the next round of ingot internal scanning and modification. The specific process is as follows: the control system calculates the focal offset caused by the change in optical path based on the refractive index parameter of the current high refractive index liquid and the thickness parameter of the free liquid phase interface, and performs optical compensation adjustment on the Z-axis focusing depth of the processing laser beam to counteract the optical influence of the liquid phase layer and ensure that the laser can be accurately focused again on the next predetermined depth inside the ingot.

[0036] After compensation, the laser focus is precisely positioned 250 μm below the surface of the current ingot (i.e., 500 μm deep inside the original ingot). After the focusing depth compensation is completed, the scanning and refining process in step S1 is repeated, allowing the ultrashort pulse laser to penetrate the high refractive index liquid layer and act on the interior of the ingot, inducing nonlinear material refining and microcrack initiation again, constructing a new weak bonding interface, and preparing for the peeling of the next wafer.

[0037] S5. Cyclic operation enables continuous stripping of multiple pieces.

[0038] Repeat steps S2 to S4, that is, sequentially complete the cycle of temperature gradient stripping, liquid phase planarization repair, and refractive index compensation scanning modification, stripping the wafers one by one until the entire silicon carbide ingot is stripped.

[0039] The special ingot carrier and liquid holding fixture used in this embodiment is integrated into the motion and clamping module of the processing system. The fixture includes a groove-shaped base with a closed outer peripheral sidewall. The bottom of the base is provided with a carrier area for adsorbing and fixing the silicon carbide ingot. The closed outer peripheral sidewall and the fixed ingot sidewall together form an upward-opening liquid holding space to accommodate high refractive index liquid, prevent liquid leakage, and provide a stable working cavity for ultrasonic vibration.

[0040] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. For example, the parameters of the ultrashort pulse laser can be adjusted within the range of wavelength 355nm~1064nm, pulse width 190fs~15ps, and single pulse energy 5μJ~50μJ; the scanning crystal orientation can also be selected from the [1-100] crystal orientation; the modified scanning interval, predetermined depth, temperature gradient parameters, ultrasonic parameters, and the type of high refractive index liquid (such as glycerol, special laser high refractive index matching liquid) can all be adapted and adjusted according to actual processing requirements. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0041] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for continuous multi-wafer peeling of silicon carbide ingots based on scattering suppression and thermal stress, characterized in that, Includes the following steps: S1. Focus an ultrashort pulse laser to a predetermined depth inside a silicon carbide ingot and perform scanning modification along a set trajectory to construct a weak bonding interface inside the crystal. S2. By applying a differential thermal field to both sides of the weak bonding interface through temperature gradient-induced peeling treatment, a temperature gradient is formed near the weak bonding interface and thermal stress is generated by applying a low temperature to one end of the silicon carbide ingot and a controlled high temperature to the other end, thereby causing the material to undergo cleavage fracture along the weak bonding interface to complete the separation of the single wafer. After wafer peeling, the silicon carbide ingot exhibits a rough peeling surface with microscopic unevenness on the separated side; S3. A high refractive index liquid is dropped onto the rough peeling surface of a silicon carbide ingot. The high refractive index liquid is covered on the rough peeling surface by relying on the physical filling effect of the fluid. This is used to suppress the scattering of laser light by the rough peeling surface and achieve optical flattening and refractive index matching of the rough peeling surface. S4. A refractive index compensation continuous scanning strategy is adopted so that the ultrashort pulse laser is refocused on a predetermined depth inside the silicon carbide ingot after passing through the high refractive index liquid for scanning and quality improvement, thereby constructing a new weak bonding interface for the peeling of the next wafer. S5. Repeat steps S2 to S4 to sequentially peel off multiple wafers until all silicon carbide ingots are peeled off.

2. The method for continuous multi-wafer peeling of silicon carbide ingots based on scattering suppression and thermal stress as described in claim 1, characterized in that: In step S1, the weakly bonded interface formed consists of periodically alternating modified zones and microcracks.

3. The method for continuous multi-wafer peeling of silicon carbide ingots based on scattering suppression and thermal stress as described in claim 1, characterized in that: In steps S1 and S4, the wavelength of the ultrashort pulse laser is 355nm~1064nm, the pulse width is 190fs~15ps, and the single pulse energy is 5μJ~50μJ.

4. The method for continuous multi-wafer peeling of silicon carbide ingots based on scattering suppression and thermal stress as described in claim 1, characterized in that: In step S1, the set trajectory is a linear array fed along the [1-100] or [11-20] crystal orientation at a set remodeling scan interval at a predetermined depth; the remodeling scan interval is 30μm~150μm; the predetermined depth is 100μm~600μm below the upper surface of the silicon carbide ingot.

5. The method for continuous multi-wafer peeling of silicon carbide ingots based on scattering suppression and thermal stress as described in claim 1, characterized in that: In step S2, the temperature gradient induced stripping process includes applying a low temperature to the wafer side to be stripped, the stripping start end, or the area adjacent to the weak bonding interface of the silicon carbide ingot to form a low temperature end, while applying a controlled high temperature to the opposite end or the other end of the ingot body to form a high temperature end, so that a temperature gradient is formed on both sides of the weak bonding interface, and the duration of the temperature gradient is 5s to 600s; wherein, the temperature of the low temperature end is -196℃ to 25℃, the temperature of the high temperature end is 200℃ to 300℃, and the temperature of the high temperature end is lower than the temperature that causes changes in the silicon carbide lattice structure, thermal damage, or chemical reaction with the surrounding medium.

6. The method for continuous multi-wafer peeling of silicon carbide ingots based on scattering suppression and thermal stress as described in claim 1, characterized in that: In step S3, the refractive index parameter of the high refractive index liquid is matched with the refractive index of the silicon carbide material to minimize Fresnel reflection and optical scattering at the liquid-solid composite interface; the high refractive index liquid includes at least one of diiodomethane, glycerol, or laser high refractive index matching liquid.

7. The method for continuous multi-wafer peeling of silicon carbide ingots based on scattering suppression and thermal stress as described in claim 1, characterized in that, In step S3, after adding high-refractive-index liquid to the rough peeling surface using a dropper, the process further includes: using ultrasonic vibration to assist in liquid phase planarization treatment, so that the high-refractive-index liquid can spread uniformly while filling the micro-uneven structure of the surface, and promote the desorption, coalescence and escape of bubbles inside the high-refractive-index liquid, forming a free liquid phase interface with uniform thickness and an optically flat upper surface; the thickness of the free liquid phase interface is 5μm~100μm; the frequency of the ultrasonic vibration is 20kHz~100kHz, the ultrasonic power is 20W~500W, and the ultrasonic treatment time is 60s~600s.

8. The method for continuous multi-wafer peeling of silicon carbide ingots based on scattering suppression and thermal stress as described in claim 1, characterized in that, In step S4, the specific process of the refractive index compensation continuous scanning strategy is as follows: when performing the next internal scanning modification, the focusing depth of the processing laser beam is optically compensated and adjusted according to the refractive index of the high refractive index liquid and the thickness parameters of the free liquid phase interface, so as to ensure that the laser is refocused on the next predetermined depth inside the ingot.

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