A method for plasma control of laser-induced crack propagation in silicon carbide wafers

Abstract

The application relates to a laser-induced silicon carbide wafer crack propagation plasma control method, which comprises the following steps: laser focusing is carried out at a to-be-processed position of a silicon carbide crystal ingot, and a high excitation state plasma is generated in the crystal ingot; after the plasma is generated, an external magnetic field or an electric field is applied to control the movement state of the plasma, so that the crack propagates along a predetermined path and depth; characteristic parameters of the plasma are monitored in real time, data is transmitted to a feedback control system, laser parameters, magnetic field or electric field intensity are dynamically adjusted according to the movement state of the plasma; the crack growth range is expanded through multiple scanning, and wafer peeling is realized. The laser-induced silicon carbide wafer crack propagation plasma control method can effectively control the crack propagation path and depth, avoid the disordered propagation of the crack, greatly reduce the material damage in the silicon carbide wafer processing process, efficiently peel the silicon carbide wafer, improve the processing speed, and improve the quality of the final product.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high-end equipment manufacturing technology of semiconductor materials, and particularly relates to a plasma control method for laser-induced crack propagation of a silicon carbide wafer. BACKGROUND

[0002] With the increasing demand for material quality of semiconductor devices, silicon carbide (SiC) wafers have become the ideal material for the next generation of power electronic devices due to their wide bandgap, high thermal conductivity, high breakdown electric field and high saturated electron drift speed. However, silicon carbide is hard and brittle, and traditional mechanical processing methods not only have low efficiency, but also easily cause material damage, affecting the final quality of the wafer.

[0003] In current SiC processing technology, laser stealth cutting technology realizes the separation of materials by inducing cracks in the inside of the crystal ingot, greatly improving the cutting efficiency. However, in the crack control process of the prior art, irregular cracks are often generated in the processing process due to improper laser power control or unstable laser-induced crack propagation path, increasing the wafer breakage rate. Therefore, how to more effectively control the propagation direction and depth of the crack is a key problem to improve the processing quality and efficiency.

[0004] In view of this, the present application is proposed. SUMMARY

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

[0006] In a first aspect of the present application, a plasma control method for laser-induced crack propagation of a silicon carbide wafer is provided, characterized by comprising the following steps:

[0007] S1, focusing laser at a to-be-processed position of a silicon carbide ingot to generate high-excitation-state plasma in the inside of the ingot.

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

[0009] In the present application, by using an ultrafast pulsed laser, the thermal diffusion effect of 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 pulsed laser is in the range of femtoseconds to picoseconds, preferably 500 fs to 10 ps.

[0011] S2, after the plasma is generated, an external magnetic field or electric field is applied to control the movement state of the plasma, so that the crack extends along a predetermined path and depth.

[0012] Specifically, step S2 includes: after the plasma is generated, the external magnetic field or electric field applied controls 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 one specific embodiment, for a 0.5mm thick silicon carbide wafer, the magnetic field strength is controlled in the range of 0.5T to 0.7T, and the electric field strength is controlled in the range of 1500V to 2500V.

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

[0017] S3, real-time monitoring of the characteristic parameters of the plasma, and transmitting the data to the feedback control system, dynamically adjusting the laser parameters, magnetic field or electric field strength according to the movement state of the plasma.

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

[0019] In the present application, by introducing an external magnetic field or electric field to control the movement trajectory of the plasma, it is ensured that the crack extends along a predetermined path. At the same time, by adjusting the depth and scanning speed of the laser focal point, the growth depth and direction of the crack are controlled, and the generation of irregular cracks is avoided.

[0020] In the present application, the characteristic parameters of the plasma are monitored in real time by the feedback control system, and the laser parameters and field strength are adjusted in real time, so that the crack growth process is dynamically optimized, and the processing accuracy and quality are further improved.

[0021] S4, multiple scanning to extend the crack growth range, realizing the peeling of the wafer.

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

[0023] After the initial laser scanning, the crack grows along the direction perpendicular to the laser beam; during the subsequent scanning process, a laser beam with a pulse width larger than that of the initial scanning is used in combination with plasma control to further guide the crack propagation in a specific direction; multiple scans can gradually expand the crack growth range to achieve precise separation of the wafer.

[0024] In a second aspect, the application provides a processing device for laser-induced crack propagation of a silicon carbide wafer, which adopts the above-mentioned plasma control method for laser-induced crack propagation of a silicon carbide wafer, comprising: an ultrafast pulsed laser, an external magnetic or electric field generating device, a control system and a feedback system.

[0025] The ultrafast pulsed laser is used to focus laser on the processing position of the silicon carbide ingot to generate high excitation state plasma inside the ingot;

[0026] The external magnetic or electric field generating device controls the movement state of the plasma by applying an external magnetic or electric field to make the crack propagate along a predetermined path and depth;

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

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

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

[0030] (1) The application can effectively control the crack propagation path and depth by controlling the movement of laser-induced plasma, avoid disordered crack propagation, and greatly reduce material damage during SiC wafer processing.

[0031] (2) The application further improves the accuracy and quality of processing by monitoring the plasma characteristic parameters through the feedback control system and dynamically adjusting the laser parameters and field strength.

[0032] (3) The application can efficiently separate the SiC wafer by using plasma control technology combined with multiple laser scanning, improve the processing speed, reduce the wafer breakage rate during cutting, and improve the quality of the final product. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort based on these drawings.

[0034] Figure 1 The schematic diagram of the principle of the laser-induced plasma crack disorder expansion provided by the present application.

[0035] Figure 2 The microscopic photograph of the laser-induced 0.5mm-thick SiC wafer crack disorder expansion provided by the present application.

[0036] Figure 3 The schematic diagram of the principle of the external electric field (electric field placement mode 1) controlling the plasma crack ordered expansion provided by the present application.

[0037] Figure 4 The microscopic photograph of the external electric field (electric field placement mode 1) controlling the 0.5mm-thick SiC wafer crack ordered expansion provided by the present application.

[0038] Figure 5 The schematic diagram of the principle of the external electric field (electric field placement mode 2) controlling the plasma crack ordered expansion provided by the present application.

[0039] Figure 6 The microscopic photograph of the external electric field (electric field placement mode 2) controlling the 0.5mm-thick SiC wafer crack ordered expansion provided by the present application.

[0040] Figure 7 The schematic diagram of the principle of the external magnetic field (magnetic field placement mode 1) controlling the plasma crack ordered expansion provided by the present application.

[0041] Figure 8 The microscopic photograph of the external magnetic field (magnetic field placement mode 1) controlling the 0.5mm-thick SiC wafer crack ordered expansion provided by the present application.

[0042] Figure 9 The schematic diagram of the principle of the external magnetic field (magnetic field placement mode 2) controlling the plasma crack ordered expansion provided by the present application.

[0043] Figure 10 The microscopic photograph of the external magnetic field (magnetic field placement mode 2) controlling the 0.5mm-thick SiC wafer ordered expansion provided by the present application. DETAILED DESCRIPTION

[0044] It should be noted that the following detailed description is illustrative only, and is intended to provide further description in connection with the exemplary embodiments according to the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

[0045] It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It is further understood that the terms "comprising," "including," and "having" and variations thereof, as used herein, are intended to be equivalent to the term "consisting of." Thus, the terms "comprising," "including," and "having" and variations thereof, as used herein, are intended to be inclusive.

[0046] The technical solutions of the present application will be described in detail below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0047] Example 1: External electric field control of SiC wafer crack propagation

[0048] In this embodiment, for two kinds of SiC wafers with thickness of 0.5mm and 1mm, the real-time regulation of external electric field is used to realize the accurate control of crack path. A femtosecond laser with green wavelength band (517nm) is used to process the wafer to verify the effect of external electric field on crack growth. The specific operation steps are as follows:

[0049] (I) Experimental materials and equipment

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

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

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

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

[0054] (II) Experimental steps

[0055] 1. Laser focusing and plasma generation

[0056] Using a femtosecond laser beam with a green wavelength of 517 nm, the laser is focused at a depth of 500 microns and 800 microns below the surface of 0.5 mm and 1 mm thick SiC wafers, respectively. The laser generates a high-temperature plasma locally through a multiphoton ionization mechanism, inducing initial cracks. Due to the extremely short pulse width of femtosecond laser, it can achieve high-precision processing in local areas, reduce heat diffusion, and form cracks with an initial direction perpendicular to the laser beam direction.

[0057] 2. External electric field control of plasma

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

[0059] The control effect is that different electric field intensities will affect the stability and path precision of crack expansion. Through comparison, it is found that for the 0.5 mm thick wafer, when the electric field is controlled at 1500 V to 2500 V, the crack expansion path is stable, and there are fewer bifurcated cracks, with a crack depth error of about ±10 μm; for the 1 mm thick wafer, when the electric field is controlled at 2500 V to 3500 V, the crack depth error is controlled within ±15 μm.

[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 intensity are dynamically adjusted to ensure that the cracks expand along the set path and depth. For example, in the 0.5 mm thick wafer experiment, the electric field intensity is controlled at 2000 V and the laser power is fine-tuned to 5%, the crack expansion is uniform, avoiding the generation of disordered cracks.

[0062] 4. Multiple scanning to expand crack growth range

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

[0064] For the 0.5 mm thick wafer, the average crack expansion speed is 10 μm / s;

[0065] For the 1 mm thick wafer, the average crack expansion speed is 8 μm / s.

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

[0067] (III) Data Comparison and Effect Analysis

[0068] By comparing the crack propagation effect without using electric field control (as shown in Figures 1-2 , it is proved that the embodiment has the following advantages:

[0069] 1. Crack path control

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

[0071] 2. Reduce the heat affected zone

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

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

[0074] The external electric field control not only ensures the uniform growth of the crack, but also improves the crack propagation speed. Compared with the experimental group without using electric field control, the crack growth speed of 0.5mm thick wafer is improved by about 20%, and the crack growth speed of 1mm thick wafer is improved by 15%. In addition, the crack propagation realized by electric field regulation reduces the crack bifurcation phenomenon, significantly improving the processing quality.

[0075] 4. Final processing quality

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

[0077] The principle diagram of crack propagation of SiC wafer under different external electric fields (electric field placement mode 1 and 2) is shown in 3 and 5. In this embodiment, for 0.5mm thick SiC wafer, the micrographs of crack propagation under different external electric fields are shown in Figure 4 and 6As shown in the figures, under the electric field placement modes 1 and 2, the cracks are orderly expanded.

[0078] In this embodiment, the effectiveness of using a femtosecond laser in the green light band combined with an external electric field to control the crack expansion of a SiC wafer is verified. The external electric field precisely controls the movement of the plasma, achieving consistency in the crack path and precise regulation of the depth. Compared with the traditional method without electric field control, this embodiment greatly improves the processing efficiency, reduces thermal damage, and ensures the high-quality peeling of the SiC wafer, providing a feasible optimization path for semiconductor processing.

[0079] This embodiment also provides a processing device for laser-induced crack expansion of a silicon carbide wafer, which comprises: 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 laser on the to-be-processed position of the silicon carbide ingot to generate high excitation state plasma inside the ingot; the pulse width of the laser is in the femtosecond to picosecond range;

[0081] The external electric field generating device regulates the movement state of the plasma by applying an external electric field, so that the crack expands along a predetermined path and depth; the strength 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 the strength of the electric field to control the expansion process of the crack; the control system can dynamically adjust the depth and scanning speed of the laser focal point 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 the monitoring data to the control system to realize accurate control of the crack expansion process; the feedback system comprises a plurality of sensors for monitoring the characteristic parameters of the plasma and providing real-time data to the control system.

[0084] Example 2: External magnetic field control of SiC wafer crack expansion

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

[0086] (I) Experimental materials and equipment

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

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

[0089] 3. Magnetic field generating device: maximum magnetic induction intensity 1 T, using electromagnet to generate stable magnetic field direction and can adjust intensity in 0 to 1 T range.

[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 the crack grows according to the set path and depth.

[0091] (II) Experimental steps

[0092] 1. Laser focusing and plasma generation

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

[0094] 2. Magnetic field regulation of plasma

[0095] After the generation of plasma, different intensity external magnetic fields are applied to control its trajectory, so as to realize the uniform growth of the crack. On a 0.5 mm thick wafer, the magnetic field intensity increases from 0.4 T to 0.7 T; on a 1 mm thick wafer, the magnetic field gradually adjusts from 0.6 T to 1 T, ensuring that the crack path expands along the set direction.

[0096] The control effect of the above includes: by adjusting the magnetic field intensity and direction, the direction and depth of crack expansion are accurately controlled, and the generation of irregular cracks is reduced. The specific performance is as follows:

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

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

[0099] 3. Dynamic feedback control

[0100] The sensor system is used to monitor the characteristics (density, temperature and position) of the plasma in real time, and the feedback control system adjusts the magnetic field intensity and direction according to these data to optimize the crack expansion path. For example, on a 0.5 mm thick wafer, as the plasma density increases, the magnetic field intensity gradually increases from 0.4 T to 0.6 T, ensuring that the crack expands stably according to the set path.

[0101] 4. Multiple laser scanning to extend crack growth range

[0102] After the initial scanning to generate cracks, a secondary scanning is performed under the control of an applied magnetic field to further extend the crack growth range. The laser pulse width is adjusted to 1 picosecond and the pulse frequency is reduced to 150 kHz to allow the crack to extend at an appropriate speed:

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

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

[0105] After the secondary scanning, the crack reaches the target depth and the wafer surface is precisely peeled off.

[0106] (III) Data comparison and effect analysis

[0107] By comparing the crack extension effect without using magnetic field control (as shown in FIG. 5), it is proved that the present embodiment has the following significant advantages: Figures 1-2 1. Crack path control

[0108] After using magnetic field control, the crack extension path is more uniform and irregular cracks are reduced. The crack depth error of a 0.5 mm thick wafer without using magnetic field is about ± 30 μm, while under the control of a 0.5 T-0.7 T magnetic field, the error is reduced to ± 12 μm. The crack depth error of a 1 mm thick wafer is reduced from ± 40 μm to ± 15 μm.

[0109] 2. Reduce heat-affected zone

[0110] Femtosecond laser combined with magnetic field regulation of plasma effectively reduces the range of heat-affected zone. In the magnetic field control group of 0.5 mm and 1 mm thick, the heat-affected zone is reduced by about 30%, ensuring high-quality peeling of the material.

[0111] 3. Improve crack extension speed and processing accuracy

[0112] Magnetic field control significantly improves the growth speed of the crack. Compared with the control group without using magnetic field control, the crack growth speed of a 0.5 mm thick wafer is increased by 18%, and that of a 1 mm thick wafer is increased by 15%. In addition, magnetic field control reduces the crack bifurcation phenomenon, making the processed surface smoother.

[0113] 4. Final processing quality

[0114]

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

[0116] The principle diagram of crack propagation of SiC wafer under the application of different external magnetic fields (magnetic field placement mode 1 and 2) is shown in Figures 7 and 9. In this embodiment, the micrographs of crack propagation of 0.5mm thick SiC wafer under the application of different external magnetic fields are shown in Figures Figure 8 and 10 From the figures, it can be seen that under the magnetic field placement mode 1 and 2, the crack is orderly propagated.

[0117] In this embodiment, by using femtosecond laser in green light band and external magnetic field to cooperatively control the movement of plasma, the regulation effect of magnetic field in the crack growth process of SiC wafer is verified. The magnetic field control not only effectively improves the stability of crack path, but also significantly improves the crack propagation speed, reduces the thermal damage, improves the processing surface quality and efficiency, and provides a feasible technical path for high-quality SiC wafer processing.

[0118] This embodiment also provides a processing equipment for laser-induced crack propagation of SiC wafer, which adopts, comprising: an ultrafast pulse laser, an external magnetic field generating device, a control system and a feedback system;

[0119] The ultrafast pulse laser is used for laser focusing on the to-be-processed position of the SiC crystal ingot to generate high excitation state plasma inside the crystal ingot; the pulse width of the laser is in the range of femtosecond to picosecond;

[0120] The external magnetic field generating device regulates the movement state of the plasma by applying an external magnetic field, so that the crack propagates along a predetermined path and depth; the strength of the external magnetic field is adjusted according to the real-time parameters of the plasma;

[0121] The control system is used for real-time monitoring of the characteristic parameters of the plasma and dynamic adjustment of the laser parameters and the magnetic field strength to control the crack propagation process; the control system can dynamically adjust the depth and scanning speed of the laser focal point to ensure that the crack propagates along the predetermined path and avoid the generation of irregular cracks;

[0122] The feedback system is used for transmitting the monitoring data to the control system to realize accurate control of the crack propagation process; the feedback system includes a plurality of sensors for monitoring the characteristic parameters of the plasma and providing real-time data to the control system.

[0123] In summary, by controlling the movement of laser-induced plasma, the present application can effectively control the crack propagation path and depth, avoid the disorderly expansion of the crack, and greatly reduce the material damage in the SiC wafer processing process; by monitoring the plasma characteristic parameters through the feedback control system, dynamically adjusting the laser parameters and field strength, the processing accuracy and quality are further improved; by using the ultrafast pulse laser, the thermal 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; by using the plasma control technology combined with multiple laser scanning, the SiC wafer can be efficiently peeled off, the processing speed is improved, the wafer breakage rate in the cutting process is reduced, and the quality of the final product is improved.

[0124] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of plasma control of laser-induced crack propagation in silicon carbide wafers, characterized in that, The method comprises the following steps: S1, using an ultrafast pulsed laser to focus laser on the position to be processed of a silicon carbide ingot, generating high excitation state plasma inside the ingot; the pulse width of the ultrafast pulsed laser ranges from 500 fs to 10 ps; S2, after the plasma is generated, an external magnetic field or electric field is applied to regulate the movement state of the plasma, so that the crack extends along a predetermined path and depth; for a 0.5 mm thick silicon carbide wafer, the strength of the magnetic field is controlled at 0.5 T to 0.7 T, and the strength of the electric field is controlled at 1500 V to 2500 V; for a 1 mm thick silicon carbide wafer, the strength of the magnetic field is controlled at 0.7 T to 1 T, and the strength of the electric field is controlled at 2500 V to 3500 V; S3, real-time monitoring of the characteristic parameters of the plasma is performed, and the data is transmitted to a feedback control system, and the laser parameters, the strength of the magnetic field or the electric field are dynamically adjusted according to the movement state of the plasma; S4, multiple scanning is performed to extend the crack growth range, and wafer peeling is realized.

2. The plasma controlled method of laser-induced silicon carbide wafer crack propagation according to claim 1, wherein, Step S1 comprises: using an ultrafast pulsed laser to focus laser on the position to be processed of a silicon carbide ingot, generating high excitation state plasma inside the ingot through multi-photon ionization, tunnel ionization and avalanche ionization mechanism.

3. The plasma controlled method of laser-induced silicon carbide wafer crack propagation according to claim 1, wherein, Step S2 comprises: after the plasma is generated, the external magnetic field or electric field is applied to control the growth path and depth of the crack by real-time adjusting the trajectory and density of the plasma.

4. The plasma controlled method of laser-induced silicon carbide wafer crack propagation according to claim 1, wherein, In step S3, the characteristic parameters of the plasma include the density, temperature and position of the plasma; the laser parameters include the laser power, pulse frequency and focal depth.

5. A processing apparatus for laser-induced crack propagation of a silicon carbide wafer, characterized by, The method for laser-induced plasma control of silicon carbide wafer crack extension according to any one of claims 1-4 is used to induce crack extension of a silicon carbide wafer, and the processing equipment comprises: an ultrafast pulsed laser, an external magnetic field or electric field generating device, a control system and a feedback system; The ultrafast pulsed laser is used to focus laser on the position to be processed of a silicon carbide ingot, to generate high excitation state plasma inside the ingot; The external magnetic field or electric field generating device regulates the movement state of the plasma by applying an external magnetic field or electric field, so that the crack extends along a predetermined path and depth; The control system is used to real-time monitor the characteristic parameters of the plasma and dynamically adjust the laser parameters, the strength of the magnetic field or the electric field, to control the crack extension process; The feedback system is used to transmit the monitoring data to the control system, to realize accurate control of the crack extension process.

Images