A method for ultrasonic stripping of silicon carbide using cyclic ultrasonic media-assisted ultrasound

Abstract

This invention discloses a method for ultrasonic exfoliation of silicon carbide using a circulating ultrasonic medium-assisted process, comprising the following steps: S1. A near-infrared femtosecond laser is compressed to the diffraction limit and focused at 300 μm inside a silicon carbide wafer. The laser is controlled to scan layer by layer to form a continuous brittle modified layer with a thickness of 100 μm inside the silicon carbide wafer. S2. A single-ring cut is made along the side of the silicon carbide wafer using an ultraviolet laser, penetrating the modified layer to a depth of 80 μm to 120 μm with a narrow slit, extending to a depth of 10 μm to 30 μm in the substrate, forming a narrow annular opening groove. S3. A miniature ultrasonic probe is embedded at an inclined angle into the bottom of the annular opening groove, and a suspension is injected to form a stable liquid film. An initial stage of ultrasonic crack initiation is performed, followed by an expansion stage where the crack is driven to propagate along the plane of the modified layer. S4. The separated silicon carbide sheet is adsorbed using a vacuum suction cup, and any remaining liquid film is removed. This invention can control crack path deviation, heat-affected zone range, and surface roughness to extremely low levels.

Description

Technical Field

[0001] This invention relates to the field of precision machining technology for third-generation semiconductor materials, specifically a method for ultrasonic stripping of silicon carbide using cyclic ultrasonic media-assisted ultrasonic stripping. Background Technology

[0002] In the thinning process of silicon carbide wafers, traditional laser refining processes pose a significant risk of thermal damage. Existing technologies typically employ high-energy-density lasers, such as those with an energy density greater than 10... 8 W / cm 2 A high-energy laser processing method is used to modify the full thickness of silicon carbide wafers to form internal crack or void layers. However, this process inevitably generates microcracks on the wafer surface, which can penetrate into the functional layers, leading to performance degradation or even device failure. Studies have shown that the microcrack density on the surface of silicon carbide wafers after conventional laser processing can reach 125 cracks / cm². 2 This severely impacts the reliability and electrical performance of devices. Furthermore, the laser thermal effect can lead to localized material degradation, further limiting processing accuracy and quality.

[0003] For the peeling of 300µm ultrathin silicon carbide wafers, mechanical peeling is a common and traditional method. However, this method relies on precise stress matching, and in practice, uneven stress distribution can easily lead to wafer breakage. Experimental data shows that the breakage rate of mechanical peeling is as high as 38%, and the yield is less than 60%. Especially in the processing of large-size (6-8 inch) wafers, the instability problem of mechanical peeling is even more prominent. Because the direction and speed of crack propagation cannot be effectively controlled during mechanical peeling, the surface roughness of the peeled wafer is high (Ra>2μm), which further affects the subsequent processing and performance of the device. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for ultrasonic peeling of silicon carbide using cyclic ultrasonic media that can control crack path deviation, heat-affected zone range, and surface roughness to an extremely low level.

[0005] This invention is achieved through the following technical solution: a method for ultrasonic stripping of silicon carbide using a circulating ultrasonic medium-assisted method, comprising the following steps:

[0006] S1. By combining an aspherical lens with an adaptive optics module for synergistic focusing, the near-infrared femtosecond laser is compressed to the diffraction limit and focused to 300µm inside the silicon carbide wafer. The laser focus is parallel to the silicon carbide wafer surface. The laser is controlled to form a continuous brittle modified layer with a thickness of 100µm inside the silicon carbide wafer in a layer-by-layer scanning manner. The porosity of the modified layer is controlled by the energy density gradient to generate a uniform micropore and crack network.

[0007] S2. A rubber sleeve is fitted around the outer periphery of the ultrasonic probe. The ultrasound is started, and at the same time, the microfluidic system is activated to inject a suspension into the rubber sleeve, so that the suspension wraps around the ultrasonic probe to form a stable liquid film. Vibration energy is transmitted through the liquid film. First, the ultrasonic crack is initiated in the initial stage, and then the ultrasonic crack is driven to expand 360° along the plane of the modified layer in the expansion stage. The expansion speed and path accuracy are monitored in real time. After the acoustic emission sensor captures the crack closure signal, the ultrasonic drive is immediately terminated, and the ultrasonic probe and the rubber sleeve are removed together.

[0008] S3. Use a vacuum chuck to adsorb the separated silicon carbide wafers.

[0009] Further: Before performing step S2, a single-ring cut is made along the side of the silicon carbide wafer using an ultraviolet laser, and a narrow slit of 15um to 30um is made to penetrate the modified layer to a depth of 80um to 120um and extend to a depth of 10um to 30um in the substrate to form a narrow slit annular opening groove. Then, a miniature ultrasonic probe is embedded at an inclined angle into the bottom of the annular opening groove.

[0010] Further: When performing step S2, multiple ultrasonic probes are distributed circumferentially on the modified layer, and the distance between any two adjacent ultrasonic probes is 10mm-100mm.

[0011] Further: The near-infrared femtosecond laser described in step S1 uses a femtosecond fiber laser as the light source. The wavelength range of the femtosecond fiber laser is 1000nm to 1100nm, the pulse width range is 300fs to 500fs, the repetition frequency range is 50kHz to 200kHz, and the focused spot diameter range is less than 5um.

[0012] The energy density increases from 0.8 J / cm² at the top along the thickness direction of the modified layer. z Gradual transition to 1.2 J / cm at the bottom z This induces the directional dissociation of the silicon carbide lattice, forming a uniformly distributed micropore and nanocrack mesh, thus optimizing the brittle structure of the modified layer. The thickness tolerance of the modified layer is within ±10%, and the parallelism deviation between the plane of the modified layer and the main crystal plane of the wafer is less than or equal to 0.5°.

[0013] Furthermore: the ultraviolet laser uses an ultraviolet laser as the light source, the ultraviolet laser is a DPSS Q-switched laser source, the working wavelength range of the ultraviolet laser is 300nm to 380nm, the pulse energy range of the ultraviolet laser is 1mJ to 3mJ, and the pulse width range of the ultraviolet laser is 10ns to 30ns;

[0014] When the ultraviolet laser performs a single-circle annular cut along the side of the silicon carbide wafer, a coaxial vision positioning system integrating a high-resolution CCD camera is used. The resolution range of the CCD camera is 3µm to 10µm. The CCD camera, combined with a dynamic compensation algorithm, monitors the cutting position on the side of the wafer in real time and corrects the path deviation caused by wafer warping, ensuring that the concentricity error range of the annular opening groove is less than or equal to 5µm.

[0015] Furthermore, the width of the annular opening groove is controlled between 10µm and 35µm, and the cutting speed of the ultraviolet laser is between 30mm / s and 100mm / s.

[0016] Furthermore: the diameter of the miniature ultrasonic probe ranges from 40µm to 60µm, and the tip of the miniature ultrasonic probe integrates a conical diffuser with a diffusion angle range of 50° to 70°, which directs and focuses ultrasonic energy to the bottom of the annular opening groove.

[0017] Furthermore, the miniature ultrasonic probe is embedded into the bottom of the annular opening groove using a six-axis robot at an angle ranging from 20° to 40°, and the embedding depth of the miniature ultrasonic probe is from 70µm to 100µm.

[0018] Furthermore: When using the aforementioned miniature ultrasonic probe for initial ultrasonic crack initiation, a low-frequency continuous ultrasonic laser crack initiation with a frequency range of 50kHz to 60kHz and a power range of 2W to 4W is employed.

[0019] During the propagation stage, when the ultrasonically driven crack propagates along the plane of the modified layer in 360°, a high-frequency pulsed ultrasound with a frequency range of 70kHz to 90kHz, a duty cycle range of 30% to 50%, and a peak power range of 7W to 10W is used to accelerate the propagation of the crack along the plane of the modified layer in 360° using pulsed shock waves.

[0020] Furthermore: When using the ultrasonic probe for initial ultrasonic crack initiation, a low-frequency continuous ultrasonic laser crack initiation with a frequency range of 50kHz to 60kHz and a power range of 20W to 40W is used.

[0021] During the propagation stage, when the ultrasonically driven crack propagates 360° along the plane of the modified layer, a high-frequency pulsed ultrasound with a frequency range of 70kHz to 90kHz and a power range of 70W to 100W is used to accelerate the propagation of the crack along the plane of the modified layer 360° using pulsed shock waves.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. Near-infrared femtosecond laser is used to construct the modified layer. Ultraviolet light ring side cutting and liquid-guided ultrasonic synergistic expansion and ablation are combined. The non-thermal melting modification process combined with low thermal impact ultraviolet cutting technology significantly improves the yield of thin films and reduces the risk of breakage. It avoids the surface damage and microcrack problems caused by high-energy laser and mechanical stress in traditional processes, and ensures the integrity of the device's functional layer.

[0024] 2. Based on the precise positioning of the modified layer and the dynamic compensation of the ultraviolet cutting path, combined with the synergistic propagation mechanism of liquid-conducting ultrasound, the crack can be stably propagated along the preset path, and the separation surface can achieve high flatness and low roughness, meeting the stringent requirements of power devices for substrate surface quality.

[0025] 3. Supports automated processing of large-size silicon carbide wafers, optimizes efficiency through three-axis linkage process, significantly shortens processing cycle, and is suitable for the large-scale production needs of high-performance semiconductor substrates in fields such as new energy vehicles and 5G communications. Attached Figure Description

[0026] Figure 1 This is a flowchart of the method for ultrasonic stripping of silicon carbide using a circulating ultrasonic medium-assisted process according to the present invention.

[0027] Figure 2 This is a side view showing the fabrication process of the liquid-encapsulated ultrasonic probe of the present invention.

[0028] Figure 3 This is a side view of the fabrication process of a single ultrasonic probe according to the present invention;

[0029] Figure 4 This is the ultrasonic probe used during liquid filling in this invention.

[0030] Explanation of reference numerals in the attached figures: 1-Silicon carbide wafer, 2-Modified layer, 3-Annular opening groove, 4-Liquid-encapsulated ultrasonic probe, 5-Conical diffuser, 6-Single ultrasonic probe, 7-Suspension, 8-Rubber sleeve. Detailed Implementation

[0031] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[0032] Example 1

[0033] In this embodiment, an n-type silicon carbide wafer with a thickness of 300 μm and a size of 6 inches is selected, and the silicon carbide is thinned using the circulating ultrasonic medium-assisted ultrasonic stripping method provided in this invention.

[0034] Reference Figures 1 to 4 The specific steps of a method for ultrasonic stripping of silicon carbide using cyclic ultrasonic media-assisted ultrasonication are as follows:

[0035] S1. By combining an aspherical lens with an adaptive optics module for synergistic focusing, the near-infrared femtosecond laser is compressed to the diffraction limit and focused at 300µm inside the silicon carbide wafer. The laser focus is parallel to the silicon carbide wafer surface. The laser is controlled to form a continuous brittle modified layer with a thickness of 100µm inside the silicon carbide wafer in a layer-by-layer scanning manner. The porosity of the modified layer is controlled by the energy density gradient to generate a uniform micropore and crack network.

[0036] S2. A rubber sleeve is fitted around the outer periphery of the ultrasonic probe. The ultrasound is started, and at the same time, the microfluidic system is activated to inject a suspension into the rubber sleeve, so that the suspension surrounds the ultrasonic probe to form a stable liquid film. Vibrational energy is transmitted through the liquid film. First, the ultrasonic crack is initiated in the initial stage, and then the ultrasonic crack is driven to expand 360° along the plane of the modified layer in the expansion stage. The expansion speed and path accuracy are monitored in real time. After the acoustic emission sensor captures the crack closure signal, the ultrasonic drive is immediately terminated, and the ultrasonic probe and the rubber sleeve are removed together.

[0037] Before performing step S2, a single-ring cut is made along the side of the silicon carbide wafer using an ultraviolet laser, and a narrow slit of 15um to 30um is made to penetrate the modified layer to a depth of 80um to 120um and extend to a depth of 10um to 30um in the substrate to form a narrow slit annular opening groove. Then, a miniature ultrasonic probe is embedded at an inclined angle into the bottom of the annular opening groove.

[0038] S3. Use a vacuum chuck to adsorb the separated silicon carbide wafers.

[0039] In step S1, as an optional option in this embodiment, the near-infrared femtosecond laser uses a near-infrared femtosecond fiber laser with a wavelength of 1030 nm, a pulse width of 400 fs, a repetition rate of 100 kHz, a single pulse energy of 1.0 μJ, and a beam quality M. 2 The laser strength is 1.2, the spot diameter is 4 μm, and the laser energy density in the thickness direction of the modified layer (Z-axis direction) decreases from 0.8 J / cm at the top. z Gradual transition to 1.2 J / cm at the bottom z The porosity was adjusted to 38%.

[0040] In this embodiment, optical coherence tomography (OCT) verified that the thickness tolerance of the modified layer was ±8%, the plane parallelism deviation was 0.3°, the surface heat-affected zone (HAZ) was ≤1.5µm, and there were no microcracks penetrating the functional layer.

[0041] The ultraviolet laser uses a Q-switched ultraviolet laser with a wavelength of 355nm, a pulse energy of 2mJ, and a pulse width of 20ns. It performs single-circle annular cutting at a speed of 50mm / s. A coaxial vision positioning system is used to dynamically compensate for wafer warpage with a resolution of 5µm and a maximum compensation energy of 40µm. This forms an annular opening groove with a width of 25µm and a depth of 120µm, penetrating the modified layer by 100µm and extending to the substrate by 20µm. The heat-affected zone has a width of 12µm and a residual stress release rate of 75%.

[0042] A 50µm diameter micro-ultrasound probe with a conical diffuser at a 60° diffusion angle was inserted into the bottom of an annular opening groove at a 30° tilt angle to a depth of 80µm. Simultaneously, a microfluidic system injected a deionized water-based suspension at a rate of 1.2µL / min to form an 8µm thick liquid film. In the initial stage, continuous ultrasound at 50kHz was used, and a 3W laser was used to initiate the crack, which took 1.2 seconds. In the subsequent propagation stage, pulsed ultrasound at 80kHz with a duty cycle of 40% and a peak power of 8W was used to drive the crack to propagate 360° along the modified layer plane at a speed of 1.5mm / s. An acoustic emission sensor captured a 100kHz closing signal in real time, and the response time was 8ms before automatically terminating.

[0043] In step S3, the roughness Ra of the separation surface was measured to be 45 nm using a white light interferometer, and scanning electron microscopy (SEM) showed no microcracks or edge defects. The electrical performance qualification rate of the device reached 98.5%.

[0044] This embodiment achieves a yield of 92%, a heat-affected zone of ≤1.5µm, and a crack path deviation of ≤10µm, which are significantly better than traditional processes. This verifies the technical advantages of the present invention in suppressing thermal damage, improving surface quality, and controlling the propagation path.

[0045] This method achieves high-precision, non-destructive separation of silicon carbide wafers through a three-stage collaborative process chain. First, a near-infrared femtosecond laser constructs a non-thermally fusible, brittle modified layer inside the silicon carbide wafer. Then, an ultrashort pulse and adaptive optics focusing technology are used to form a microcrack network with controllable porosity, overcoming the thermal accumulation defects of traditional high-energy lasers and avoiding damage to the surface functional layer. Second, the short-wavelength characteristics of ultraviolet lasers are utilized to perform annular side cutting, forming a narrow-slit annular opening groove with low thermal impact, precisely releasing residual stress and establishing a directional crack propagation boundary, significantly reducing the risk of thermally induced structural failure compared to traditional infrared laser processes. Finally, a liquid-encapsulated miniature ultrasonic probe is introduced. Through liquid film lubrication and dynamic control of ultrasonic energy, the cracks are driven to propagate uniformly along the modified layer plane. Combined with real-time acoustic emission monitoring technology, the propagation process is precisely controlled, completely solving the problems of random bifurcation and edge chipping caused by stress concentration in traditional mechanical peeling.

[0046] Example 2

[0047] S1. By combining an aspherical lens with an adaptive optics module for synergistic focusing, the near-infrared femtosecond laser is compressed to the diffraction limit and focused at 300µm inside the silicon carbide wafer. The laser focus is parallel to the silicon carbide wafer surface. The laser is controlled to form a continuous brittle modified layer with a thickness of 100µm inside the silicon carbide wafer in a layer-by-layer scanning manner. The porosity of the modified layer is controlled by the energy density gradient to generate a uniform micropore and crack network.

[0048] S2. A rubber sleeve is fitted around the outer periphery of the ultrasonic probe. The ultrasound is started, and at the same time, the microfluidic system is activated to inject a suspension into the rubber sleeve, so that the suspension surrounds the ultrasonic probe to form a stable liquid film. Vibrational energy is transmitted through the liquid film. First, the ultrasonic crack is initiated in the initial stage, and then the ultrasonic crack is driven to expand 360° along the plane of the modified layer in the expansion stage. The expansion speed and path accuracy are monitored in real time. After the acoustic emission sensor captures the crack closure signal, the ultrasonic drive is immediately terminated, and the ultrasonic probe and the rubber sleeve are removed together.

[0049] When performing the ultrasound activation in step S2, multiple ultrasound probes are arranged in a circular pattern on the modified layer, with the distance between any two adjacent ultrasound probes being 10mm-100mm.

[0050] S3. Use a vacuum chuck to adsorb the separated silicon carbide wafers.

[0051] In step S1, as an optional option in this embodiment, the near-infrared femtosecond laser uses a near-infrared femtosecond fiber laser with a wavelength of 1030 nm, a pulse width of 400 fs, a repetition rate of 100 kHz, a single pulse energy of 1.0 μJ, and a beam quality M. 2 The laser strength is 1.2, the spot diameter is 4 μm, and the laser energy density in the thickness direction of the modified layer (Z-axis direction) decreases from 0.8 J / cm at the top. z Gradual transition to 1.2 J / cm at the bottom z The porosity was adjusted to 38%.

[0052] In this embodiment, optical coherence tomography (OCT) verified that the thickness tolerance of the modified layer was ±8%, the plane parallelism deviation was 0.3°, the surface heat-affected zone (HAZ) was ≤1.5µm, and there were no microcracks penetrating the functional layer.

[0053] The ultrasonic probe has a pulse width of 200 ps, ​​a speed of 100-500 mm / s, and a pulse energy of 5 uJ. When using the ultrasonic probe for initial ultrasonic crack initiation, a low-frequency continuous ultrasonic laser crack initiation with a frequency range of 50 kHz to 60 kHz and a power range of 20 W to 40 W is used.

[0054] During the propagation stage, when the ultrasonically driven crack propagates 360° along the plane of the modified layer, a high-frequency pulsed ultrasound with a frequency range of 70kHz to 90kHz and a power range of 70W to 100W is used to accelerate the propagation of the crack along the plane of the modified layer 360° using pulsed shock waves.

[0055] In this embodiment, a non-thermally fusible brittle modified layer is constructed inside the wafer using a near-infrared femtosecond laser. A microcrack network with controllable voids is formed by ultrashort pulses and adaptive optics focusing technology, overcoming the thermal accumulation defects of traditional high-energy lasers and avoiding functional damage. Then, a liquid-encased ultrasonic probe is used to drive the cracks to propagate uniformly along the plane of the modified layer through liquid film lubrication and dynamic adjustment of ultrasonic energy. Peeling can also be performed without the need for grooving.

[0056] The suspension described in this invention may be pure water, pure oil, ethanol, or a mixture of pure water and starch, metal powder or non-metal powder, or a mixture of pure oil and starch, metal powder or non-metal powder, or a mixture of ethanol and starch, metal powder or non-metal powder.

[0057] Comparative Example 1

[0058] This example uses the same preparation method as the embodiment, but differs from the embodiment in that it employs a traditional high-energy laser modification combined with mechanical exfoliation to process a 300 μm thick, 6-inch n-type silicon carbide wafer. First, a full-thickness modification process is performed using an Nd:YAG solid-state laser with a wavelength of 1064 nm, a pulse width of 100 ns, and an energy density of 1 × 10⁻⁶. 8 High-energy lasers were used to create a porous layer inside the wafer. Testing revealed that laser processing resulted in a heat-affected zone width of 50 μm and penetrating microcracks with a density of 110 cracks / cm² beneath the functional layer, severely damaging the device's insulation performance. A mechanical peeling process was then employed, directly separating the wafer by applying a vertical 200N pull force using a vacuum chuck. During peeling, uneven stress distribution led to large-scale fragmentation at the wafer's edges, with a fragmentation rate of 42% and a final yield of only 58%. Scanning electron microscopy revealed a surface roughness Ra of 2.3 μm, a maximum edge chipping length of 500 μm, and localized fractures in the gate oxide layer due to stress concentration. Electrical performance testing showed that due to the penetrating microcracks and surface damage, the device leakage current increased tenfold compared to the previous example, and the threshold voltage drift exceeded 15%. Defect analysis revealed that the thermal accumulation effect of the high-energy laser caused an amorphization transformation of the silicon carbide lattice, resulting in an inhomogeneous brittle structure in the modified layer and random branching and propagation of cracks during mechanical peeling. Simultaneously, the lack of a stress-guiding mechanism caused the sheet to be subjected to asymmetric loads during separation, ultimately leading to uncontrolled fragmentation. This comparative example verifies the fundamental deficiencies of traditional processes in thermal damage control, stress matching, and propagation path planning.

[0059] Comparative Example 2

[0060] This example was prepared using the same method as the previous example. The difference between this example and the previous example is that an infrared laser side-cutting and liquid-film-free ultrasonic propagation process was used to process a 300 μm thick, 6-inch n-type silicon carbide wafer. First, a CO2 laser was used for side-cutting at a wavelength of 10.6 μm, an average power of 50 W, and a pulse width of 200 ns, cutting a 50 μm wide annular groove at a speed of 30 mm / s. Due to the significant thermal effect of the infrared laser, the heat-affected zone of the cut area reached 80 μm in width, and the local temperature at the groove edge exceeded 1800°C, inducing graphitization of silicon carbide. The brittle structure of the modified layer was destroyed, and the residual stress release rate was less than 40%. Subsequently, a single ultrasonic probe (60 μm in diameter, without a conical diffuser) was directly inserted into the bottom of the groove, and continuous ultrasonic vibration at 60 kHz and a power of 10 W was applied. Due to the lack of liquid film lubrication and directional energy transfer, the crack propagation resistance increased, the initial crack initiation time was extended to 5 seconds, and the propagation speed fluctuated between 0.2 and 3 mm / s. When the acoustic emission sensor detected the crack closure signal, the response time exceeded 50ms, causing the crack to over-propagate to a depth of 30μm in the substrate, with a path deviation of 50μm. Multiple chipping points appeared at the edge of the peeled sheet, with a maximum length of 200μm. Scanning electron microscopy revealed a thermally induced microcrack network at the separation surface, with a density of 75 cracks / cm² and a surface roughness Ra=1.8μm. Electrical performance testing showed that the device leakage current increased by 6 times compared to the previous example, and the threshold voltage drifted by 12%. Defect analysis indicated that the high thermal input of the infrared laser caused the lattice reconstruction failure of the modified layer, weakening its crack guiding effect; the lack of liquid film cooling and lubrication reduced the ultrasonic energy transfer efficiency, and the local temperature rise triggered secondary thermal stress, exacerbating the instability of crack propagation. The final yield was only 65%, verifying the negative impact of thermal damage defects and liquid film deficiency in the infrared laser process on the ultrasonic propagation mechanism.

[0061] The above detailed description is a specific description of feasible embodiments of the present invention. These embodiments are not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included in the patent scope of this case.

Claims

1. A method for ultrasonic stripping of silicon carbide using a circulating ultrasonic medium-assisted method, characterized in that: Includes the following steps: S1. By combining an aspherical lens with an adaptive optics module for synergistic focusing, the near-infrared femtosecond laser is compressed to the diffraction limit and focused to 300µm inside the silicon carbide wafer. The laser focus is parallel to the silicon carbide wafer surface. The laser is controlled to form a continuous brittle modified layer with a thickness of 100µm inside the silicon carbide wafer in a layer-by-layer scanning manner. The porosity of the modified layer is controlled by the energy density gradient to generate a uniform micropore and crack network. S2. Using an ultraviolet laser, a single-ring cut is made along the side of the silicon carbide wafer, and a narrow slit of 15µm to 30µm is made to penetrate the modified layer to a depth of 80µm to 120µm, extending to a depth of 10µm to 30µm in the substrate, forming a narrow slit annular opening groove. A micro ultrasonic probe is then embedded at an inclined angle into the bottom of the annular opening groove. A rubber sleeve is fitted around the outer periphery of the ultrasonic probe. The ultrasonic wave is started, and at the same time, a microfluidic system is activated to inject a suspension into the rubber sleeve, so that the suspension envelops the ultrasonic probe to form a stable liquid film. Vibrational energy is transmitted through the liquid film. First, the ultrasonic crack is initiated in the initial stage, and then the ultrasonic crack is driven to expand 360° along the plane of the modified layer in the propagation stage. The propagation speed and path accuracy are monitored in real time. After the acoustic emission sensor captures the crack closure signal, the ultrasonic drive is immediately terminated, and the ultrasonic probe and the rubber sleeve are removed together. S3. Use a vacuum suction cup to adsorb the separated silicon carbide sheets; The ultraviolet laser uses an ultraviolet laser as a light source, the ultraviolet laser is a DPSS Q-switched laser source, the working wavelength range of the ultraviolet laser is 300nm to 380nm, the pulse energy range of the ultraviolet laser is 1mJ to 3mJ, and the pulse width range of the ultraviolet laser is 10ns to 30ns. When the ultraviolet laser performs a single-circle annular cut along the side of the silicon carbide wafer, a coaxial vision positioning system integrating a high-resolution CCD camera is used. The resolution range of the CCD camera is 3µm to 10µm. The CCD camera, combined with a dynamic compensation algorithm, monitors the cutting position on the side of the wafer in real time and corrects the path deviation caused by wafer warping, ensuring that the concentricity error range of the annular opening groove is less than or equal to 5µm.

2. The method for ultrasonic stripping of silicon carbide using a circulating ultrasonic medium-assisted method according to claim 1, characterized in that: In step S2, multiple ultrasonic probes are arranged in a circular pattern on the modified layer, with the distance between any two adjacent ultrasonic probes being 10mm-100mm.

3. The method for ultrasonic stripping of silicon carbide using a circulating ultrasonic medium-assisted method according to claim 1, characterized in that: The near-infrared femtosecond laser described in step S1 uses a femtosecond fiber laser as the light source. The wavelength range of the femtosecond fiber laser is 1000nm to 1100nm, the pulse width range is 300fs to 500fs, the repetition frequency range is 50kHz to 200kHz, and the focused spot diameter range is less than 5µm. The energy density is 0.8 J / cm² from the top in the thickness direction of the modified layer. z Gradual transition to 1.2 J / cm at the bottom z This induces the directional dissociation of the silicon carbide lattice, forming a uniformly distributed micropore and nanocrack mesh, thus optimizing the brittle structure of the modified layer. The thickness tolerance of the modified layer is within ±10%, and the parallelism deviation between the plane of the modified layer and the main crystal plane of the wafer is less than or equal to 0.5°.

4. The method for ultrasonic stripping of silicon carbide using a circulating ultrasonic medium-assisted method according to claim 1, characterized in that: The width of the annular opening groove is controlled between 10µm and 35µm, and the cutting speed of the ultraviolet laser is between 30mm / s and 100mm / s.

5. The method for ultrasonic stripping of silicon carbide using a circulating ultrasonic medium-assisted method according to claim 1, characterized in that: The diameter of the miniature ultrasonic probe ranges from 40 μm to 60 μm, and the tip of the miniature ultrasonic probe integrates a conical diffuser with a diffusion angle ranging from 50° to 70°, which directs and focuses ultrasonic energy to the bottom of the annular opening groove.

6. The method for ultrasonic stripping of silicon carbide using a circulating ultrasonic medium-assisted method according to claim 1, characterized in that: The miniature ultrasonic probe is embedded into the bottom of the annular opening groove using a six-axis robot at an angle ranging from 20° to 40°, with an embedding depth of 70µm to 100µm.

7. The method for ultrasonic stripping of silicon carbide using a circulating ultrasonic medium-assisted method according to claim 1, characterized in that: When using the aforementioned miniature ultrasonic probe for initial ultrasonic crack initiation, a low-frequency continuous ultrasonic laser crack initiation is employed with a frequency range of 50kHz to 60kHz and a power range of 2W to 4W. During the propagation stage, when the ultrasonically driven crack propagates along the plane of the modified layer in 360°, a high-frequency pulsed ultrasound with a frequency range of 70kHz to 90kHz, a duty cycle range of 30% to 50%, and a peak power range of 7W to 10W is used to accelerate the propagation of the crack along the plane of the modified layer in 360° using pulsed shock waves.

8. The method for ultrasonic stripping of silicon carbide using a circulating ultrasonic medium-assisted method according to claim 2, characterized in that: When using the ultrasonic probe for initial ultrasonic crack initiation, a low-frequency continuous ultrasonic laser crack initiation with a frequency range of 50kHz to 60kHz and a power range of 20W to 40W is used. During the propagation stage, when the ultrasonically driven crack propagates 360° along the plane of the modified layer, a high-frequency pulsed ultrasound with a frequency range of 70kHz to 90kHz and a power range of 70W to 100W is used to accelerate the propagation of the crack along the plane of the modified layer 360° using pulsed shock waves.

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