Plasma control method for crack propagation of laser-induced silicon carbide wafer

Abstract

The invention relates to a plasma control method for laser-induced silicon carbide wafer crack propagation, which comprises the following steps of: performing laser focusing on a to-be-processed position of a silicon carbide crystal ingot, and generating high-excitation-state plasma in the crystal ingot; after the plasma is generated, an external magnetic field or electric field is applied to regulate and control the motion state of the plasma, so that the crack expands along a preset path and depth; characteristic parameters of the plasma are monitored in real time, data are transmitted to a feedback control system, and laser parameters and magnetic field or electric field intensity are dynamically adjusted according to the motion state of the plasma; and repeatedly scanning and expanding the crack growth range to realize the stripping of the wafer. According to the plasma control method for laser-induced crack propagation of the silicon carbide wafer, the propagation path and depth of the crack can be effectively controlled, disordered propagation of the crack is avoided, material damage in the processing process of the silicon carbide wafer is greatly reduced, the silicon carbide wafer can be efficiently stripped, the processing speed is increased, and the quality of a final product is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor material high-end equipment manufacturing, and in particular to a plasma control method for laser-induced crack propagation of a silicon carbide wafer. Background Art

[0002] As semiconductor devices continue to improve their requirements for material quality, silicon carbide (SiC) wafers have become ideal materials for the next generation of power electronic devices due to their excellent properties such as wide bandgap, high thermal conductivity, high breakdown electric field and high saturated electron drift velocity. However, silicon carbide has high hardness and high brittleness. Traditional mechanical processing methods are not only inefficient, but also easily cause material damage, affecting the final quality of the wafer.

[0003] In the current SiC processing technology, laser invisible cutting technology achieves material separation by laser-induced cracks inside the ingot, which greatly improves the cutting efficiency. However, in the crack control process of the existing technology, improper laser power control or unstable laser-induced crack propagation path often lead to irregular cracks in the processing process, increasing the breakage rate of the wafer. Therefore, how to more effectively control the crack propagation direction and depth is a key issue to improve processing quality and efficiency.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a plasma control method for laser-induced crack propagation of silicon carbide wafers, which can solve the problems of unstable crack propagation path and large damage in the prior art and realize efficient and high-precision processing of SiC wafers.

[0006] A first aspect of the present invention provides a plasma control method for laser-induced crack propagation in a silicon carbide wafer, characterized in that it comprises the following steps:

[0007] S1. Focusing the laser on the position to be processed of the silicon carbide ingot generates highly excited plasma inside the ingot.

[0008] Specifically, step S1 includes: using an ultrafast pulse laser to focus the laser at the position to be processed of the silicon carbide ingot, and generating a highly excited plasma inside the ingot through multi-photon ionization, tunnel ionization and avalanche ionization mechanisms. The plasma generates extremely high temperature and pressure in a local area, thereby inducing microcracks.

[0009] In the present invention, by using an ultrafast pulse laser, the heat diffusion effect of the laser in the material is reduced, the damage of the heat-affected zone is significantly reduced, and the surface integrity of the SiC wafer is ensured.

[0010] Preferably, the pulse width of the ultrafast pulse laser is in the range of femtoseconds to picoseconds, preferably 500fs to 10ps.

[0011] S2. After the plasma is generated, an external magnetic field or electric field is applied to regulate the motion state of the plasma so that the cracks extend along a predetermined path and depth.

[0012] Specifically, step S2 includes: after the plasma is generated, applying an external magnetic field or electric field to control the growth path and depth of the crack by adjusting the trajectory and density of the plasma in real time.

[0013] Preferably, the magnetic field strength is controlled in the range of 0.4T to 1T, more preferably 0.5T to 1T.

[0014] Preferably, the electric field strength is controlled in the range of 1000V to 4000V, more preferably 1500V to 3500V.

[0015] In a specific embodiment, for a 0.5 mm thick silicon carbide wafer, the magnetic field strength is controlled to be between 0.5 T and 0.7 T, and the electric field strength is controlled to be between 1500 V and 2500 V.

[0016] In another specific embodiment, for a 1 mm thick silicon carbide wafer, the magnetic field strength is controlled to be between 0.7 T and 1 T, and the electric field strength is controlled to be between 2500 V and 3500 V.

[0017] S3. Monitor the characteristic parameters of the plasma in real time and transmit the data to the feedback control system to dynamically adjust the laser parameters, magnetic field or electric field strength according to the motion state of the plasma.

[0018] Preferably, in step S3, the characteristic parameters of the plasma include but are not limited to: density, temperature and position of the plasma; and the laser parameters include but are not limited to: laser power, pulse frequency and focal depth.

[0019] In the present invention, an external magnetic field or electric field is introduced to control the motion trajectory of the plasma to ensure that the cracks expand along a predetermined path. At the same time, the depth and scanning speed of the laser focus are adjusted to control the growth depth and direction of the cracks and avoid the generation of irregular cracks.

[0020] In the present invention, the characteristic parameters of plasma are monitored in real time by a feedback control system, the laser parameters and field intensity are adjusted in real time, and the crack growth process is dynamically optimized, thereby further improving the processing accuracy and quality.

[0021] S4. Multiple scans are performed to expand the crack growth range and realize chip peeling.

[0022] Specifically, step S4 includes: after the initial scan generates a crack on a predetermined path, a subsequent scan is performed using a laser beam with a larger pulse width to further guide the crack to expand, expand the crack growth range, and achieve wafer peeling.

[0023] After the initial laser scan, the crack grows in a direction perpendicular to the laser beam. In subsequent scans, a laser beam with a pulse width greater than that of the initial scan is used, combined with plasma control, to further guide the crack to expand in a specific direction. Multiple scans can gradually expand the crack growth range and achieve precise separation of the wafer.

[0024] A second aspect of the present invention provides a processing device for laser-induced crack growth in a silicon carbide wafer, using the above-mentioned plasma control method for laser-induced crack growth in a silicon carbide wafer, comprising: an ultrafast pulse laser, an external magnetic field or electric field generating device, a control system and a feedback system;

[0025] The ultrafast pulse laser is used to focus the laser on the position to be processed of the silicon carbide ingot to generate highly excited plasma inside the ingot;

[0026] The external magnetic field or electric field generating device regulates the motion state of the plasma by applying an external magnetic field or electric field, so that the cracks extend along a predetermined path and depth;

[0027] The control system is used to monitor the characteristic parameters of the plasma in real time and dynamically adjust the laser parameters, magnetic field or electric field intensity to control the crack expansion process;

[0028] The feedback system is used to transmit monitoring data to the control system to achieve accurate control of the crack propagation process.

[0029] The beneficial effects of the present invention include at least:

[0030] (1) The present invention can effectively control the propagation path and depth of cracks by controlling the motion of laser-induced plasma, thereby avoiding disorderly propagation of cracks and significantly reducing material damage during SiC wafer processing.

[0031] (2) The present invention monitors the characteristic parameters of the plasma through a feedback control system and dynamically adjusts the laser parameters and field intensity, thereby further improving the accuracy and quality of processing.

[0032] (3) The present invention adopts plasma control technology combined with multiple laser scans, which can efficiently peel off SiC wafers, improve the processing speed, and reduce the wafer breakage rate during the cutting process, thereby improving the quality of the final product. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 A schematic diagram of the principle of disorderly expansion of laser-induced plasma cracks provided by the present invention.

[0035] Figure 2 This is a micrograph of the disordered propagation of cracks in a 0.5 mm thick SiC wafer induced by laser provided by the present invention.

[0036] Figure 3 Schematic diagram of the principle of controlling orderly expansion of plasma cracks by an external electric field (electric field placement method 1) provided by the present invention.

[0037] Figure 4 This is a micrograph of the orderly propagation of cracks in a 0.5 mm thick SiC wafer controlled by an external electric field (electric field placement method 1) provided by the present invention.

[0038] Figure 5 Schematic diagram of the principle of controlling orderly expansion of plasma cracks by an external electric field (electric field placement method 2) provided by the present invention.

[0039] Figure 6 This is a micrograph of the orderly expansion of cracks in a 0.5 mm thick SiC wafer controlled by an external electric field (electric field placement method 2) provided by the present invention.

[0040] Figure 7 Schematic diagram of the principle of controlling the orderly expansion of plasma cracks by the external magnetic field (magnetic field placement method 1) provided by the present invention.

[0041] Figure 8 This is a micrograph of the orderly expansion of cracks in a 0.5 mm thick SiC wafer controlled by an external magnetic field (magnetic field placement mode 1) provided by the present invention.

[0042] Fig. 9 Schematic diagram of the principle of orderly expansion of plasma cracks in an external magnetic field (magnetic field placement mode 2) provided by the present invention.

[0043] Fig.10 This is a micrograph of the orderly expansion of a 0.5 mm thick SiC wafer controlled by an external magnetic field (magnetic field placement method 2) provided by the present invention. DETAILED DESCRIPTION

[0044] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0045] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0046] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Example 1 External electric field controls crack growth in SiC wafers

[0048] In this embodiment, for two SiC wafers with thicknesses of 0.5 mm and 1 mm, the crack path is precisely controlled by real-time regulation of the external electric field. This experiment uses a femtosecond laser in the green light band (517 nm) to process the wafer to verify the effect of the external electric field on crack growth. The specific operation steps are as follows:

[0049] 1. Experimental materials and equipment

[0050] 1. Experimental materials: SiC wafers with thickness of 0.5 mm and 1 mm respectively.

[0051] 2. Laser parameters: Femtosecond laser, wavelength 517 nm, pulse width 500 femtoseconds (fs), pulse frequency set to 200 kHz.

[0052] 3. Electric field device: A DC electric field generating device with an adjustable voltage range of 0-5000V, used to control the crack path and depth.

[0053] 4. Sensor system: used to monitor plasma characteristic parameters, including density, temperature and position, to ensure real-time feedback control of electric field strength.

[0054] (II) Experimental steps

[0055] 1. Laser focusing and plasma generation

[0056] Using a 517nm femtosecond laser beam in the green band, the laser was focused at a depth of 500 microns and 800 microns below the surface of a 0.5mm and 1mm thick SiC wafer, respectively. The laser generated high-temperature plasma locally through a multi-photon ionization mechanism, inducing initial cracks. Due to the extremely short pulse width of the femtosecond laser, high-precision processing can be achieved in local areas, reducing heat diffusion, and the initial direction of the crack formed is perpendicular to the direction of the laser beam.

[0057] 2. External electric field to control plasma

[0058] After the plasma is generated, electric fields of different strengths are applied to control the plasma so that the cracks grow along a predetermined path and depth. In the experiment, the electric field strength was gradually increased from 1000V to 3000V on a 0.5mm thick wafer, and from 2000V to 4000V on a 1mm thick wafer, ensuring that the cracks grow evenly along the appropriate path and avoiding irregular crack expansion.

[0059] The control effect is: different electric field strengths will affect the stability and path accuracy of crack extension. By comparison, it is found that for 0.5mm thick wafers, when the electric field is controlled at 1500V to 2500V, the crack extension path is stable, there are fewer bifurcated cracks, and the crack depth error is about ±10μm; for 1mm thick wafers, when the electric field is controlled at 2500V to 3500V, the crack depth error is controlled at ±15μm.

[0060] 3. Feedback control and dynamic adjustment

[0061] The sensor monitors the density, position and temperature of the plasma in real time and transmits the data to the feedback control system. According to the state of the plasma, the laser power and electric field strength are dynamically adjusted to ensure that the cracks extend along the set path and depth. For example, in the 0.5mm thick wafer experiment, the electric field strength was controlled at 2000V and the laser power was fine-tuned to 5%, and the cracks extended evenly, avoiding the generation of disordered cracks.

[0062] 4. Multiple scans to expand the crack growth range

[0063] After the initial scan generates a crack on the predetermined path, a second scan is performed using a laser beam with a larger pulse width to further expand the crack in a specific direction. In the experiment, the laser pulse width was increased to 2 picoseconds (ps) and the pulse frequency was reduced to 100kHz to moderately increase the crack growth rate:

[0064] For a 0.5 mm thick wafer, the average crack growth rate is 10 μm / s;

[0065] For a 1mm thick wafer, the average crack growth rate is 8μm / s.

[0066] After the second scan, the crack depth reached the predetermined target area, achieving precise peeling of the SiC wafer.

[0067] (III) Data comparison and effect analysis

[0068] By comparing the crack growth effect without electric field control (such as Figure 1-2 It is shown that this embodiment has the following significant advantages:

[0069] 1. Crack path control

[0070] The external electric field significantly improves the crack path consistency. The crack depth error of a 0.5mm thick wafer without electric field control is ±30μm, while under 1500V-2500V electric field control, the error is reduced to ±10μm. The crack depth error of a 1mm thick wafer is also reduced from ±40μm to ±15μm.

[0071] 2. Reduce heat affected zone

[0072] Under the action of femtosecond laser, the use of green band laser effectively reduced heat diffusion, while electric field control further reduced the range of the heat affected zone. In the 0.5mm and 1mm thick wafer experiments, the heat affected zone of the electric field assisted group was reduced by about 35%-40%.

[0073] 3. Improve crack propagation speed and processing accuracy

[0074] External electric field control increases the crack propagation speed while ensuring uniform crack growth. Compared with the experimental group without electric field control, the crack growth rate of 0.5mm thick wafers increased by about 20%, and the crack growth rate of 1mm thick wafers increased by 15%. In addition, crack propagation achieved through electric field regulation reduces crack bifurcation and significantly improves processing quality.

[0075] 4. Final processing quality

[0076] With the assistance of the electric field, the surface integrity of the SiC wafer is significantly improved. The roughness of the wafer peeling surface using the external electric field is reduced by about 25%, and the edge cracking is reduced by 20%. In this embodiment, the final surface roughness of the 0.5mm thick wafer is Ra 0.8nm, and the surface roughness of the 1mm thick wafer is Ra 1.1nm, which meets the requirements of high-quality semiconductor device manufacturing.

[0077] The schematic diagrams of the crack extension principle of SiC wafer under different external electric fields (electric field placement modes 1 and 2) are shown in Figures 3 and 5. In this embodiment, for a 0.5 mm thick SiC wafer, microscopic photos of crack extension under different external electric fields are shown in Figures 4 and 5. Figure 4 and 6As shown in the figure, it can be seen that under electric field placement methods 1 and 2, the cracks expand in an orderly manner.

[0078] In this embodiment, the effectiveness of controlling the crack propagation of SiC wafers by combining green light band femtosecond laser with external electric field was verified. The external electric field achieves the consistency of crack path and precise control of depth by precisely controlling the movement of plasma. Compared with the traditional method without electric field control, this embodiment greatly improves the processing efficiency, reduces thermal damage, ensures high-quality peeling of SiC wafers, and provides a feasible optimization path for semiconductor processing.

[0079] This embodiment also provides a processing device for laser-induced crack growth in silicon carbide wafers, which includes: an ultrafast pulse laser, an external electric field generating device, a control system, and a feedback system;

[0080] The ultrafast pulse laser is used to focus the laser on the position to be processed of the silicon carbide ingot to generate highly excited plasma inside the ingot; the pulse width of the laser is in the range of femtoseconds to picoseconds;

[0081] The external electric field generating device controls the motion state of the plasma by applying an external electric field, so that the cracks extend along a predetermined path and depth; the intensity of the external electric field is adjusted according to the real-time parameters of the plasma;

[0082] The control system is used to monitor the characteristic parameters of the plasma in real time and dynamically adjust the laser parameters and electric field strength to control the crack expansion process; the control system can dynamically adjust the depth and scanning speed of the laser focus to ensure that the crack expands along the predetermined path and avoid the generation of irregular cracks;

[0083] The feedback system is used to transmit monitoring data to the control system to achieve precise control of the crack propagation process; the feedback system includes multiple sensors for monitoring characteristic parameters of the plasma and providing real-time data to the control system.

[0084] Example 2 External magnetic field controls crack growth in SiC wafers

[0085] In this embodiment, SiC wafers with thicknesses of 0.5 mm and 1 mm were used as experimental objects, and an external magnetic field was applied to control the crack path and depth to verify the effect of magnetic field control in improving the crack growth accuracy. The laser used in the experiment was a green band femtosecond laser (wavelength 517 nm), and was equipped with an external magnetic field device with adjustable intensity.

[0086] 1. Experimental materials and equipment

[0087] 1. Experimental materials: SiC wafers with thickness of 0.5 mm and 1 mm respectively.

[0088] 2. Laser parameters: 517 nm femtosecond laser, pulse width 500 femtoseconds (fs), pulse frequency 200 kHz.

[0089] 3. Magnetic field generating device: The maximum magnetic induction intensity is 1T. It uses electromagnets to generate a stable magnetic field direction, and the intensity can be adjusted within the range of 0 to 1T.

[0090] 4. Feedback control system: real-time monitoring of plasma density, position and temperature, dynamic regulation of magnetic field and laser parameters to ensure that cracks grow along the set path and depth.

[0091] (II) Experimental steps

[0092] 1. Laser focusing and plasma generation

[0093] A 517nm femtosecond laser beam is focused to a depth of 500μm below the surface of a 0.5mm thick wafer and 800μm below the surface of a 1mm thick wafer, and multi-photon ionization is used to generate high-temperature plasma inside the wafer. The laser pulse width is 500fs, and the instantaneous high energy effectively reduces thermal diffusion and induces an initial crack, which is initially perpendicular to the laser beam.

[0094] 2. Magnetic field control plasma

[0095] After the plasma is generated, external magnetic fields of different strengths are applied to control its movement trajectory to achieve uniform growth of the crack. On a 0.5mm thick wafer, the magnetic field strength is increased from 0.4T to 0.7T; on a 1mm thick wafer, the magnetic field is gradually adjusted from 0.6T to 1T to ensure that the crack path expands along the set direction.

[0096] The above control effects include: by adjusting the magnetic field strength and direction, the direction and depth of crack extension are precisely controlled, and the generation of irregular cracks is reduced. The specific performance is as follows:

[0097] For a 0.5mm thick wafer, the crack depth error is controlled within ±12μm and the path is uniform under a magnetic field of 0.5T to 0.7T.

[0098] For a 1mm thick wafer, under the control of a magnetic field ranging from 0.7T to 1T, the crack depth error is approximately ±15μm, and the crack growth is stable.

[0099] 3. Dynamic feedback control

[0100] The sensor system monitors the characteristics of the plasma (density, temperature and position) in real time, and the feedback control system adjusts the magnetic field strength and direction based on these data to optimize the crack propagation path. For example, on a 0.5mm thick wafer, as the plasma density increases, the magnetic field strength gradually increases from 0.4T to 0.6T to ensure that the crack propagates stably along the set path.

[0101] 4. Multiple laser scans to expand the crack growth range

[0102] After the crack is generated by the initial scan, a second scan is performed under the control of an external magnetic field to further expand the crack growth range. The laser pulse width is adjusted to 1 picosecond and the pulse frequency is reduced to 150kHz to allow the crack to expand at a suitable speed:

[0103] For a 0.5 mm thick wafer, the crack growth rate is about 9 μm / s.

[0104] For a 1mm thick wafer, the crack growth rate is about 7μm / s.

[0105] After the second scan, the crack reached the target depth and the wafer surface was precisely peeled off.

[0106] (III) Data comparison and effect analysis

[0107] By comparing the crack growth effect without magnetic field control (such as Figure 1-2 It is shown that this embodiment has the following significant advantages:

[0108] 1. Crack path control

[0109] After using magnetic field control, the crack propagation path is more uniform and irregular cracks are reduced. The crack depth error of a 0.5mm thick wafer without a magnetic field is about ±30μm, while under 0.5T-0.7T magnetic field control, the error is reduced to ±12μm. The crack depth error of a 1mm thick wafer is reduced from ±40μm to ±15μm.

[0110] 2. Reduce heat affected zone

[0111] The femtosecond laser combined with magnetic field to control plasma effectively reduced the range of the heat-affected zone. In the 0.5mm and 1mm thick magnetic field control groups, the heat-affected zone was reduced by about 30%, ensuring high-quality stripping of the material.

[0112] 3. Improve crack propagation speed and processing accuracy

[0113] Magnetic field control significantly increases the crack growth rate. Compared with the control group without magnetic field control, the crack growth rate of 0.5mm thick wafers increased by 18%, and that of 1mm thick wafers increased by 15%. In addition, magnetic field control reduces crack bifurcation and makes the processed surface smoother.

[0114] 4. Final processing quality

[0115] After using magnetic field control, the surface roughness of the wafer is significantly improved. In the control group without magnetic field control, the surface roughness of the 0.5mm thick wafer is Ra 1.0nm, and the surface roughness of the 1mm thick wafer is Ra 1.3nm. Under magnetic field control, the surface roughness of the 0.5mm thick wafer drops to Ra 0.75nm, and the surface roughness of the 1mm thick wafer is Ra 1.0nm.

[0116] The schematic diagrams of the principle of crack extension of SiC wafer under different external magnetic fields (magnetic field placement modes 1 and 2) are shown in Figures 7 and 9. In this embodiment, the microscopic photos of crack extension of 0.5 mm thick SiC wafer under different external magnetic fields are shown in Figure 10. Figure 8 and 10 As shown in the figure, it can be seen that under magnetic field placement methods 1 and 2, the cracks expand in an orderly manner.

[0117] In this embodiment, the plasma motion is controlled by using a femtosecond laser in the green light band and an external magnetic field to verify the regulatory effect of the magnetic field on the crack growth process of SiC wafers. Magnetic field control not only effectively improves the stability of the crack path, but also significantly increases the crack propagation speed, reduces thermal damage, and improves the processing surface quality and efficiency, providing a feasible technical path for high-quality SiC wafer processing.

[0118] This embodiment also provides a processing device for laser-induced crack growth of silicon carbide wafers, which includes: an ultrafast pulse laser, an external magnetic field generating device, a control system and a feedback system;

[0119] The ultrafast pulse laser is used to focus the laser on the position to be processed of the silicon carbide ingot to generate highly excited plasma inside the ingot; the pulse width of the laser is in the range of femtoseconds to picoseconds;

[0120] The external magnetic field generating device controls the motion state of the plasma by applying an external magnetic field, so that the cracks extend along a predetermined path and depth; the intensity of the external magnetic field is adjusted according to the real-time parameters of the plasma;

[0121] The control system is used to monitor the characteristic parameters of the plasma in real time and dynamically adjust the laser parameters and magnetic field strength to control the crack expansion process; the control system can dynamically adjust the depth and scanning speed of the laser focus to ensure that the crack expands along the predetermined path and avoid the generation of irregular cracks;

[0122] The feedback system is used to transmit monitoring data to the control system to achieve precise control of the crack propagation process; the feedback system includes multiple sensors for monitoring characteristic parameters of the plasma and providing real-time data to the control system.

[0123] In summary, the present invention can effectively control the expansion path and depth of cracks through the motion control of laser-induced plasma, avoid disordered crack expansion, and greatly reduce material damage during SiC wafer processing; monitor plasma characteristic parameters through a feedback control system, dynamically adjust laser parameters and field intensity, and further improve processing accuracy and quality; by using ultrafast pulsed lasers, the thermal diffusion effect of lasers in materials is reduced, the damage to heat-affected zones is significantly reduced, and the surface integrity of SiC wafers is ensured; the use of plasma control technology combined with multiple laser scans can efficiently peel SiC wafers, improve processing speed, reduce wafer breakage rate during cutting, and improve the quality of final products.

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A plasma control method for laser-induced crack growth in silicon carbide wafers, characterized in that: The steps include: S1. Focusing the laser at the position to be processed of the silicon carbide ingot to generate highly excited plasma inside the ingot; S2. After the plasma is generated, an external magnetic field or electric field is applied to regulate the motion state of the plasma so that the cracks extend along a predetermined path and depth; S3, real-time monitoring of characteristic parameters of the plasma, and transmission of data to a feedback control system, dynamically adjusting laser parameters, magnetic field or electric field intensity according to the motion state of the plasma; S4. Multiple scans are performed to expand the crack growth range and realize chip peeling.

2. The plasma control method for laser-induced crack growth in silicon carbide wafer according to claim 1, characterized in that: Step S1 includes: using an ultrafast pulse laser to focus the laser on the position to be processed of the silicon carbide ingot, and generating highly excited plasma inside the ingot through multi-photon ionization, tunnel ionization and avalanche ionization mechanisms.

3. The plasma control method for laser-induced crack growth in silicon carbide wafer according to claim 1, characterized in that: Step S2 includes: after the plasma is generated, applying an external magnetic field or electric field to control the growth path and depth of the crack by adjusting the trajectory and density of the plasma in real time.

4. The plasma control method for laser-induced crack growth in silicon carbide wafer according to claim 1, characterized in that: In step S3, the characteristic parameters of the plasma include: density, temperature and position of the plasma; the laser parameters include: laser power, pulse frequency and focal depth.

5. The plasma control method for laser-induced crack growth in silicon carbide wafer according to claim 1, characterized in that: Step S4 includes: after the initial scan generates a crack on a predetermined path, a subsequent scan is performed using a laser beam with a larger pulse width to further guide the crack to expand, expand the crack growth range, and achieve wafer peeling.

6. The plasma control method for laser-induced crack growth in silicon carbide wafer according to claim 1, characterized in that: The magnetic field strength range is controlled to be between 0.4T and 1T.

7. The plasma control method for laser-induced crack growth in silicon carbide wafer according to claim 1, characterized in that: The electric field strength range is controlled to be between 1000V and 4000V.

8. The plasma control method for laser-induced crack growth in silicon carbide wafer according to claim 2, characterized in that: The pulse width of the ultrafast pulse laser ranges from 500 fs to 10 ps.

9. The plasma control method for laser-induced crack growth in silicon carbide wafer according to claim 1, characterized in that: For a 0.5 mm thick silicon carbide wafer, the magnetic field strength is controlled at 0.5 T to 0.7 T, and the electric field strength is controlled at 1500 V to 2500 V; for a 1 mm thick silicon carbide wafer, the magnetic field strength is controlled at 0.7 T to 1 T, and the electric field strength is controlled at 2500 V to 3500 V.

10. A processing device for laser-induced crack propagation of silicon carbide wafers, characterized in that: A plasma control method for laser-induced crack growth in a silicon carbide wafer according to any one of claims 1 to 9, comprising: an ultrafast pulse laser, an external magnetic field or electric field generating device, a control system and a feedback system; The ultrafast pulse laser is used to focus the laser on the position to be processed of the silicon carbide ingot to generate highly excited plasma inside the ingot; The external magnetic field or electric field generating device regulates the motion state of the plasma by applying an external magnetic field or electric field, so that the cracks extend along a predetermined path and depth; The control system is used to monitor the characteristic parameters of the plasma in real time and dynamically adjust the laser parameters, magnetic field or electric field intensity to control the crack expansion process; The feedback system is used to transmit monitoring data to the control system to achieve accurate control of the crack propagation process.

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