A method and device for stripping silicon carbide wafer

Abstract

The present invention provides a method and apparatus for stripping silicon carbide wafers. The method employs a first laser beam incident from the side of a silicon carbide ingot to form a heated optical path at a predetermined depth, while simultaneously focusing a second laser beam on the optical path formed by the first laser beam and scanning the optical path at burst points. The method utilizes the gradually decreasing longitudinal temperature gradient of the optical path formed by the first laser beam to induce cracks at each burst point to grow within the optical path in a direction parallel to the optical path, thereby facilitating rapid extension and connection of cracks between adjacent burst points on the same cutting path, simplifying the difficulty of connecting adjacent burst points on the same cutting path. The method can appropriately widen the spacing between different burst points on the same cutting path, enabling scanning of a cutting path of the same length using fewer burst points, thereby improving scanning efficiency, simplifying the complexity of the equipment for the first laser beam, and saving processing costs.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide ingots, and in particular to a method for stripping a silicon carbide wafer and a stripping device thereof. Background Art

[0002] Silicon carbide is a core material for the manufacture of wide-bandgap semiconductor devices. SiC devices offer numerous advantages, including high frequency, high power, high temperature resistance, radiation tolerance, interference immunity, compact size, and light weight. These advantages are unmatched by current semiconductor materials such as silicon and gallium arsenide, and their application prospects are vast. However, while SiC is a key material for the development of core devices, its processing difficulty has hindered its widespread adoption.

[0003] During the SiC ingot slicing process, the ingot undergoes cutting, flooding, polishing, and CMP (chemical mechanical polishing) to produce SiC wafers, ensuring that the surface condition meets the requirements for subsequent epitaxial growth. Currently, two technologies are used for slicing SiC ingots: traditional wire sawing and laser processing. For large SiC wafers, laser processing is 3-5 times more efficient than wire sawing, with the efficiency improvement increasing with larger diameters. Furthermore, the unique characteristics of laser processing significantly reduce material loss and improve output yield.

[0004] At present, dual laser beam cutting is mostly used for slicing silicon carbide ingots. That is, a laser beam is first used to be incident from the end face of the silicon carbide ingot to a certain depth layer position, and a burst point scan is performed at this depth layer to form a modified layer at this depth layer; then a laser beam is used to be incident from the end face of the silicon carbide ingot to the modified layer position, and the modified layer is heated and scanned to control the growth of cracks until it splits. This processing method requires the use of two laser beams in succession, and each laser beam needs to pass through the end face of the silicon carbide ingot to be incident to a certain depth layer position, and then perform multiple burst point heating and scanning at this depth layer. Therefore, a complex and long scanning route is required to complete the formation and heating of the entire modified layer, resulting in low processing efficiency. At the same time, two complex scanning systems are required to control the two laser beams scanning separately, which makes the laser equipment more complex and the processing cost higher. Summary of the Invention

[0005] The present invention provides a method for stripping a silicon carbide wafer and a stripping device thereof, thereby improving processing efficiency.

[0006] In a first aspect, the present invention provides a method for stripping a silicon carbide wafer, the method comprising:

[0007] Step 1: Providing a silicon carbide ingot to be cut;

[0008] Step 2: Using a first laser beam to illuminate the silicon carbide ingot from the side, a heating optical path is formed at a set depth layer position in the silicon carbide ingot, so that the silicon carbide material on the optical path has a gradually decreasing longitudinal temperature gradient along the propagation direction of the optical path;

[0009] Step 3: A second laser beam is incident from the end face of the silicon carbide ingot and focused on the optical path at a set depth layer position to form a blast point to modify the silicon carbide material on the optical path;

[0010] Step 4: Control the focus of the second laser beam to scan along the propagation direction of the optical path or in the opposite direction of the propagation direction to perform explosive point modification on the silicon carbide material at other positions of the optical path to form a cutting path; and the longitudinal temperature gradient can induce cracks at each explosive point to grow in a direction parallel to the optical path within the optical path.

[0011] In the above-described scheme, a first laser beam is incident from the side of the silicon carbide ingot to form a heating optical path at a set depth layer position, while a second laser beam is focused on the optical path formed by the first laser beam and scanned at burst points along the optical path. The gradually decreasing longitudinal temperature gradient of the optical path formed by the first laser beam can be utilized to induce cracks at each burst point to grow parallel to the optical path within the optical path, thereby increasing the length of the cracks at the burst point along the direction parallel to the optical path, facilitating the rapid extension and connection of cracks between two adjacent burst points on the same cutting path, thereby simplifying the difficulty of connecting cracks at adjacent burst points on the same cutting path. In application, the spacing between different burst points on the same cutting path can be appropriately widened, so that a cutting path of the same length can be scanned using fewer burst points, thereby improving scanning efficiency. That is, in the stripping method of the present application, the first laser beam and the second laser beam can be carried out simultaneously. The first laser beam is incident from the side of the silicon carbide ingot, and is mainly used to form a heating optical path at a set depth layer position of the silicon carbide ingot. When the laser beam propagates in the silicon carbide ingot, the energy of the silicon carbide material is absorbed, and the energy gradually decreases. The silicon carbide material on the optical path has a gradually decreasing longitudinal temperature gradient along the propagation direction of the optical path; and the second laser beam is incident from the end face of the silicon carbide ingot to perform a stealth cutting process on the silicon carbide material on the optical path. During this process, the longitudinal temperature gradient on the optical path can induce cracks at each burst point to grow in a direction parallel to the optical path within the optical path, thereby increasing the length of the cracks at the burst point growing in a direction parallel to the optical path, so that the cracks between two adjacent burst points on the same cutting path are quickly extended and connected together, thereby simplifying the difficulty of connecting cracks at adjacent burst points on the same cutting path. Since the two laser beams are carried out simultaneously and the first laser beam does not need to adopt a scanning process of multiple burst points, the equipment complexity of the first laser beam system can be simplified; the second laser beam can appropriately widen the distance between different burst points on the same cutting path, so that the cutting path of the same length can be scanned with fewer burst points, thereby improving scanning efficiency, improving processing efficiency, and saving processing costs.

[0012] In a specific embodiment, the method for stripping the silicon carbide wafer further comprises:

[0013] Step 5: According to the method in step 2, the first laser beam is moved to form another new heating optical path at another position of the set depth layer in the silicon carbide ingot;

[0014] Step 6: According to the method in step 3 and step 4, focus the second laser beam on the new optical path and perform spot bursting and scanning on the new optical path to form a cutting path at the new optical path position;

[0015] Step 7: Following the methods of Steps 5 and 6, multiple cutting paths are formed within the silicon carbide ingot at a predetermined depth. Cracks on adjacent cutting paths are allowed to grow perpendicular to the optical path and connect together, forming a modified layer at the predetermined depth. During the formation of a complete modified layer within the silicon carbide ingot, the first laser beam only needs to move multiple times to form multiple heating paths, eliminating the need for a scanning process involving multiple burst scans. This simplifies the equipment complexity of the first laser beam system.

[0016] In a specific embodiment, the new heating optical path in step five is parallel to the optical path in step two, which simplifies the movement of the first laser beam and can control the distribution of the cutting paths to make the cutting paths more evenly distributed.

[0017] In a specific embodiment, the multiple cutting paths formed in step seven are parallel to each other, and the spacing between any two adjacent cutting paths is equal, so that the crack induction lengths between different cutting paths are basically the same, so that the cracks are evenly distributed throughout the entire set depth layer.

[0018] In a specific embodiment, the wavelength of the first laser beam is 300-400 nm, which improves the absorption effect of the silicon carbide material, thereby making the distribution effect of the gradually decreasing longitudinal temperature gradient on the optical path better, thereby better inducing the cracks at each explosion point to grow in the direction parallel to the optical path within the optical path.

[0019] In a specific embodiment, the first laser beam is a parallel beam, which simplifies the difficulty of the first laser beam.

[0020] In a specific embodiment, the first laser beam is shaped into a beam with a spot size of 30-50 μm through an aperture, so that the cross section of the optical path is maintained at a smaller size, thereby forming a longitudinal temperature gradient with a better distribution effect on an optical path with a smaller cross section.

[0021] In one specific embodiment, the first laser beam is a Bessel beam. The light intensity along the cross section of the optical path fluctuates in a wave-like manner from the center of the first laser beam toward the edge of the first laser beam, thereby forming a transverse temperature gradient with fluctuating temperature across the cross section of the optical path. The transverse temperature gradient can induce cracks generated at each blast point to grow transversely within the optical path in a direction perpendicular to the optical path. By adopting a Bessel beam as the first laser beam, not only can the cross-sectional size of the first laser beam be reduced, thereby facilitating the formation of a longitudinal temperature gradient with a better distribution effect on an optical path with a smaller cross-section, but also the characteristic of the Bessel beam that the light intensity on the beam cross-section fluctuates in a wave-like manner from the center position of the first laser beam to the edge position of the first laser beam can be utilized to form a transverse temperature gradient with fluctuating temperature on the cross-section of the optical path. This transverse temperature gradient can induce cracks generated at each explosion point to grow laterally in the direction perpendicular to the optical path within the optical path, thereby increasing the length of the cracks at the explosion point growing in the direction perpendicular to the optical path, facilitating the rapid transverse growth and connection of cracks on adjacent cutting paths, thereby appropriately widening the spacing between adjacent cutting paths. In silicon carbide ingots of the same size, the formation of the transformation layer can be completed by emitting fewer optical paths, thereby improving processing efficiency.

[0022] In a specific embodiment, the second laser beam is incident from the end face of the silicon carbide ingot and focused at a set depth layer position as an elliptical spot, and the long axis of the elliptical spot is perpendicular to the propagation direction of the light path, so that the cracks at the explosion point of the second laser beam can grow laterally in the modified layer in a direction perpendicular to the cutting path, so that the cracks between different cutting paths can be quickly connected together, thereby improving the slicing efficiency.

[0023] In a second aspect, the present invention further provides a device for peeling off silicon carbide wafers, which includes: a stage, a first laser system, and a second laser system. The stage is used to fix the silicon carbide ingot to be cut. The first laser system is used to output a first laser beam, and uses the first laser beam to illuminate the silicon carbide ingot from the side, forming a heating optical path at a set depth layer position within the silicon carbide ingot, so that the silicon carbide material on the optical path has a gradually decreasing longitudinal temperature gradient along the propagation direction of the optical path. The second laser system is used to output a second laser beam, and uses the second laser beam to be incident from the end face of the silicon carbide ingot and focused on the optical path at the set depth layer position, forming a blast point to modify the silicon carbide material on the optical path. Among them, the second laser system and the stage can also control the focus of the second laser beam to scan along the propagation direction of the optical path or in the opposite direction of the propagation direction, so as to perform explosive point modification on the silicon carbide material at other positions of the optical path to form a cutting path; and the longitudinal temperature gradient can induce cracks at each explosive point to grow in the direction parallel to the optical path within the optical path.

[0024] In the above-described scheme, a first laser beam is incident from the side of the silicon carbide ingot to form a heating optical path at a set depth layer position, while a second laser beam is focused on the optical path formed by the first laser beam and scanned at burst points along the optical path. The gradually decreasing longitudinal temperature gradient of the optical path formed by the first laser beam can be utilized to induce cracks at each burst point to grow parallel to the optical path within the optical path, thereby increasing the length of the cracks at the burst point along the direction parallel to the optical path, facilitating the rapid extension and connection of cracks between two adjacent burst points on the same cutting path, thereby simplifying the difficulty of connecting cracks at adjacent burst points on the same cutting path. In application, the spacing between different burst points on the same cutting path can be appropriately widened, so that a cutting path of the same length can be scanned using fewer burst points, thereby improving scanning efficiency. That is, in the stripping method of the present application, the first laser beam and the second laser beam can be carried out simultaneously. The first laser beam is incident from the side of the silicon carbide ingot, and is mainly used to form a heating optical path at a set depth layer position of the silicon carbide ingot. When the laser beam propagates in the silicon carbide ingot, the energy of the silicon carbide material is absorbed, and the energy gradually decreases. The silicon carbide material on the optical path has a gradually decreasing longitudinal temperature gradient along the propagation direction of the optical path; and the second laser beam is incident from the end face of the silicon carbide ingot to perform a stealth cutting process on the silicon carbide material on the optical path. During this process, the longitudinal temperature gradient on the optical path can induce cracks at each burst point to grow in a direction parallel to the optical path within the optical path, thereby increasing the length of the cracks at the burst point growing in a direction parallel to the optical path, so that the cracks between two adjacent burst points on the same cutting path are quickly extended and connected together, thereby simplifying the difficulty of connecting cracks at adjacent burst points on the same cutting path. Since the two laser beams are carried out simultaneously and the first laser beam does not need to adopt a scanning process of multiple burst points, the equipment complexity of the first laser beam system can be simplified; the second laser beam can appropriately widen the distance between different burst points on the same cutting path, so that the cutting path of the same length can be scanned with fewer burst points, thereby improving scanning efficiency, improving processing efficiency, and saving processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A flow chart of a method for stripping a silicon carbide wafer provided in an embodiment of the present invention;

[0026] Figure 2 A flow chart of another method for stripping a silicon carbide wafer provided in an embodiment of the present invention;

[0027] Figure 3 A schematic cross-sectional view of a method for peeling a silicon carbide wafer according to an embodiment of the present invention;

[0028] Figure 4A schematic top view of the structure of a method for peeling a silicon carbide wafer provided in an embodiment of the present invention;

[0029] Figure 5 A schematic diagram of the cross-sectional light intensity distribution of a first laser beam provided in an embodiment of the present invention;

[0030] Figure 6 A schematic top view of another method for peeling a silicon carbide wafer according to an embodiment of the present invention;

[0031] Figure 7 A schematic top view of another method for peeling a silicon carbide wafer according to an embodiment of the present invention;

[0032] Figure 8 A schematic structural diagram of a silicon carbide wafer peeling device provided in an embodiment of the present invention.

[0033] Reference numerals:

[0034] 10-Silicon carbide ingot 20-First laser beam 21-Optical path 22-Second laser beam DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0036] To facilitate understanding of the silicon carbide wafer exfoliation method provided in an embodiment of the present invention, the following first describes an application scenario of the silicon carbide wafer exfoliation method provided in an embodiment of the present invention. This silicon carbide wafer exfoliation method is applied to the process of exfoliating a silicon carbide wafer from a silicon carbide ingot. The following describes this silicon carbide wafer exfoliation method in detail with reference to the accompanying drawings.

[0037] refer to Figure 1 、 Figure 3 and Figure 4 The method for peeling a silicon carbide wafer provided by an embodiment of the present invention includes:

[0038] Step 10: Providing a silicon carbide ingot 10 to be cut;

[0039] Step 20: A first laser beam 20 is used to illuminate the silicon carbide ingot 10 from the side, forming a heating optical path 21 at a set depth layer position in the silicon carbide ingot 10, so that the silicon carbide material on the optical path 21 has a gradually decreasing longitudinal temperature gradient along the propagation direction of the optical path 21;

[0040] Step 30: A second laser beam 22 is incident from the end face of the silicon carbide ingot 10 and focused on the optical path 21 at a set depth layer position to form a blast point to modify the silicon carbide material on the optical path 21;

[0041] Step 40: Control the focus of the second laser beam 22 to scan along the propagation direction of the optical path 21 or the opposite direction of the propagation direction to perform explosive point modification on the silicon carbide material at other positions of the optical path 21 to form a cutting path; and the longitudinal temperature gradient can induce cracks at each explosive point to grow in the optical path 21 along a direction parallel to the optical path 21.

[0042] In the above-described scheme, a first laser beam 20 is incident from the side of the silicon carbide ingot 10 to form a heated optical path 21 at a predetermined depth. Meanwhile, a second laser beam 22 is focused on the optical path 21 formed by the first laser beam 20 and scanned at burst points along the optical path 21. The gradually decreasing longitudinal temperature gradient along the optical path 21 formed by the first laser beam 20 is utilized to induce cracks at each burst point to grow within the optical path 21 in a direction parallel to the optical path 21. This increases the length of the cracks at the burst points along the direction parallel to the optical path 21, facilitates the rapid extension and connection of cracks between adjacent burst points on the same cutting path, and thus simplifies the difficulty of connecting cracks at adjacent burst points on the same cutting path. In practice, the spacing between different burst points on the same cutting path can be appropriately widened, so that a cutting path of the same length can be scanned using fewer burst points, thereby improving scanning efficiency. That is, in the stripping method of the present application, the first laser beam 20 and the second laser beam 22 can be carried out simultaneously. The first laser beam 20 is incident from the side of the silicon carbide ingot 10, and is mainly used to form a heating optical path 21 at a set depth layer position of the silicon carbide ingot 10. When the laser beam propagates in the silicon carbide ingot 10, as the silicon carbide material absorbs energy, the energy gradually decreases, so that the silicon carbide material on the optical path 21 has a gradually decreasing longitudinal temperature gradient along the propagation direction of the optical path 21; and the second laser beam 22 is incident from the end face of the silicon carbide ingot 10 to perform a stealth cutting process on the silicon carbide material on the optical path 21. During this process, the longitudinal temperature gradient on the optical path 21 can induce cracks at each explosion point to grow in a direction parallel to the optical path 21 within the optical path 21, thereby increasing the length of the cracks at the explosion point growing in a direction parallel to the optical path 21, so that the cracks between two adjacent explosion points on the same cutting path are quickly extended and connected together, thereby simplifying the difficulty of connecting cracks at adjacent explosion points on the same cutting path. Because the two laser beams operate simultaneously, and the first laser beam 20 does not need to use a scanning process with multiple burst points, the complexity of the equipment system for the first laser beam 20 can be simplified. The second laser beam 22 can appropriately widen the spacing between different burst points on the same cutting path, so that a cutting path of the same length can be scanned with fewer burst points, improving scanning efficiency, enhancing processing efficiency, and saving processing costs. The following is a detailed description of each of the above steps with reference to the accompanying figures.

[0043] First, refer to Figure 1 and Figure 3 , provide a silicon carbide ingot 10 to be cut. The shape of the silicon carbide ingot 10 can be, for example, but not limited to, cylindrical. Figure 8 As shown, a silicon carbide ingot 10 to be cut is held on a stage.

[0044] Next, if Figure 1 、 Figure 3and Figure 4 As shown, a first laser beam 20 is incident from the side of the silicon carbide ingot 10 to form a heating optical path 21 at a set depth layer position inside the silicon carbide ingot 10, so that the silicon carbide material on the optical path 21 has a gradually decreasing longitudinal temperature gradient along the propagation direction of the optical path 21. The first laser beam 20 is incident from the side of the silicon carbide ingot 10 to a set depth layer position inside the silicon carbide ingot 10, and a heating optical path 21 is formed at the set depth layer position of the silicon carbide ingot 10. The size of the set depth is specifically related to the thickness of the target silicon carbide wafer to be cut. The thinner the thickness of the target silicon carbide wafer to be cut, the smaller the set depth; the thicker the thickness of the target silicon carbide wafer to be cut, the larger the set depth. The first laser beam 20 is incident from the side of the silicon carbide ingot 10 mainly to form a heating optical path 21 at a predetermined depth position of the silicon carbide ingot 10. Utilizing the law that the energy of the silicon carbide material gradually decreases as the first laser beam 20 propagates in the silicon carbide ingot 10, the silicon carbide material on the optical path 21 has a gradually decreasing longitudinal temperature gradient along the propagation direction of the optical path 21. In the horizontal direction of the incident optical path 21 of the first laser beam 20, a horizontal propagation heat field with a gradient distribution is formed. Figure 4 The darker the color shown, the higher the temperature, and the lighter the color, the lower the temperature.

[0045] When selecting the wavelength of the first laser beam 20, the wavelength of the first laser beam 20 can be 300-400nm. Specifically, the wavelength of the first laser beam 20 can be any value between 300-400nm, such as 300nm, 310nm, 320nm, 330nm, 340nm, 350nm, 360nm, 370nm, 380nm, 390nm, 400nm, etc., to improve the absorption effect of the silicon carbide material, thereby making the distribution effect of the gradually decreasing longitudinal temperature gradient on the optical path 21 better, so as to better induce the cracks at each explosion point to grow in the optical path 21 along the direction parallel to the optical path 21.

[0046] The first laser beam 20 can be a parallel beam to simplify the difficulty of the first laser beam 20. When the first laser beam 20 is a parallel beam, after the first laser beam 20 is output from the first laser beam 20 light source, the first laser beam 20 can be shaped by an aperture to shape the first laser beam 20 into a beam with a spot size of 30-50 μm. This maintains the cross-section of the optical path 21 at a smaller size, facilitating the formation of a more effectively distributed longitudinal temperature gradient on the optical path 21 with a smaller cross-section. It should be explained that the spot size here refers to the boundary dimensions of the spot, such as the length, width, or diameter, and the boundary dimensions are within the range of 30-50 μm. The specific shape of the spot can be circular, elliptical, rectangular, square, etc. For example, the first laser beam 20 can be a parallel light field with a focal depth greater than 100 mm and a size of 30-50 μm, formed by a Gaussian laser passing through an LCOS or DOE.

[0047] Next, refer to Figure 1 、 Figure 3 and Figure 4 A second laser beam 22 is incident from the end face of the silicon carbide ingot 10 and focused on the optical path 21 at a set depth layer position, forming a blast point to modify the silicon carbide material on the optical path 21. It should be emphasized that when the second laser beam 22 is incident from the end face of the silicon carbide ingot 10 and focused at the set depth layer position, the first laser beam 20 is not withdrawn, but remains in the output state of step 2 above, forming a heated optical path 21 at the set depth layer position within the silicon carbide ingot 10, so that the silicon carbide material on the optical path 21 has a decreasing temperature gradient along the propagation direction of the optical path 21.

[0048] refer to Figure 3 and Figure 4 After the second laser beam 22 is incident on the end face of the silicon carbide ingot 10, a stealth cutting process is performed on the silicon carbide material along the optical path 21. During this process, the longitudinal temperature gradient along the optical path 21 can induce cracks at each burst point to grow parallel to the optical path 21. This can increase the length of the cracks at the burst point along the direction parallel to the optical path 21, allowing the cracks between two adjacent burst points on the same cutting path to quickly extend and connect together, thereby simplifying the difficulty of connecting cracks at adjacent burst points on the same cutting path.

[0049] For example, reference Figure 3 , a vertical laser beam is emitted as the second laser beam 22, and the second laser beam 22 performs invisible cutting at the set depth layer, and only performs single focus processing. Figure 8The second laser beam 22 can pass through an LCOS spatial light modulator or a DOE diffractive optical element with a specific phase distribution to form a modulated incident field. Finally, it passes through a lens to complete a Fourier transform, resulting in light intensity distributions at different coordinates on the relative focal plane. For example, after a crack is formed at the horizontally focused focus, the transverse elliptical cracking point generated by the transverse cracking point will also grow longitudinally along the propagation direction of the optical path 21, along the set depth layer position of the silicon carbide ingot 10, due to the interference of the propagating thermal field of the specific transverse temperature gradient.

[0050] Next, refer to Figure 1 、 Figure 3 and Figure 4 The focus of the second laser beam 22 is controlled to scan along the propagation direction of the optical path 21 or in the opposite direction of the propagation direction, thereby modifying the silicon carbide material at other locations along the optical path 21 at explosive points, thereby forming cutting paths. Furthermore, the longitudinal temperature gradient can induce cracks at each explosive point to grow within the optical path 21 in a direction parallel to the optical path 21. That is, the scanning path of the second laser beam 22 coincides with the optical path 21 formed by the first laser beam 20 within the silicon carbide ingot 10, so that the focus of the second laser beam 22 is always kept on the optical path 21, and explosive points are formed on the silicon carbide material on the optical path 21, thereby modifying the silicon carbide material at the location along the optical path 21. When a second laser beam 22 is focused on the optical path 21 formed by the first laser beam 20 and scanned at burst points along the optical path 21, the gradually decreasing longitudinal temperature gradient of the optical path 21 formed by the first laser beam 20 can be utilized to induce cracks at each burst point to grow within the optical path 21 in a direction parallel to the optical path 21. This increases the length of the cracks at the burst points along the direction parallel to the optical path 21, facilitates the rapid extension and connection of cracks between two adjacent burst points on the same cutting path, and thus simplifies the difficulty of connecting cracks at adjacent burst points on the same cutting path. In application, the spacing between different burst points on the same cutting path can be appropriately widened, so that a cutting path of the same length can be scanned using fewer burst points, thereby improving scanning efficiency.

[0051] Compared with the method in the prior art in which two laser beams are incident successively from the end face of the silicon carbide ingot 10, the stripping method in the present application can realize the simultaneous execution of the first laser beam 20 and the second laser beam 22. The first laser beam 20 is incident from the side of the silicon carbide ingot 10, and is mainly used to form a heating optical path 21 at a set depth layer position in the silicon carbide ingot 10. When the laser beam propagates in the silicon carbide ingot 10, as the silicon carbide material absorbs energy, the energy gradually decreases, so that the silicon carbide material on the optical path 21 has a gradually decreasing longitudinal temperature gradient along the propagation direction of the optical path 21. The second laser beam 22 is incident from the end face of the silicon carbide ingot 10 to perform a stealth cutting process on the silicon carbide material along the optical path 21. During this process, the longitudinal temperature gradient along the optical path 21 can induce cracks at each hot spot to grow in a direction parallel to the optical path 21, increasing the length of the cracks at the hot spots along the direction parallel to the optical path 21. This allows the cracks between two adjacent hot spots on the same cutting path to quickly extend and connect together, thereby simplifying the difficulty of connecting adjacent hot spots on the same cutting path. Because the two laser beams are simultaneously operating and the first laser beam 20 does not need to use a scanning process that scans multiple hot spots, the equipment complexity of the first laser beam 20 system can be simplified. The second laser beam 22 can appropriately widen the spacing between different hot spots on the same cutting path, allowing a cutting path of the same length to be scanned using fewer hot spots, improving scanning efficiency, increasing processing efficiency, and saving processing costs.

[0052] like Figure 3 and Figure 4 As shown, the second laser beam 22 is incident from the end face of the silicon carbide ingot 10 and focused on the spot at the set depth layer position can be an elliptical spot. In a more preferred embodiment, the long axis of the elliptical spot can be perpendicular to the propagation direction of the optical path 21, so that the cracks at the explosion point of the second laser beam 22 can grow horizontally in the modified layer along the direction perpendicular to the cutting path, so that the cracks between different cutting paths can be quickly connected together, thereby improving the slicing efficiency. Of course, referring to Figure 3 , and the long axis of the elliptical spot can be made parallel to the propagation direction of the optical path 21, so that the cracks at the burst point of the second laser beam 22 can grow longitudinally in the modified layer along a direction parallel to the cutting path, and the cracks at different burst points can be quickly connected together, thereby improving the slicing efficiency.

[0053] In addition, reference Figure 2 The method for stripping the silicon carbide wafer may further include:

[0054] Step 50: According to the method in step 2, the first laser beam 20 is moved to form another new heating optical path 21 at another position of the set depth layer in the silicon carbide ingot 10;

[0055] Step 60: According to the method in step 3 and step 4, the second laser beam 22 is focused on the new optical path 21 and is burst and scanned on the new optical path 21 to form a cutting path at the position of the new optical path 21;

[0056] Step 70: According to the method of steps 5 and 6, multiple cutting paths are formed at the set depth layer position in the silicon carbide ingot 10; and the cracks on adjacent cutting paths can grow and connect together in a direction perpendicular to the optical path 21 to form a modified layer at the set depth layer position. When a cutting path completes the cutting task, the system can move as a whole. The horizontally incident first laser beam 20 will be incident on a new heated optical path 21, and the new heated optical path 21 is located at the new cutting path orientation. When the horizontally incident first laser beam 20 forms a new optical path 21 at the set depth layer position in the silicon carbide ingot 10, there is also a temperature gradient field on the optical path 21 that decreases along the propagation direction. The vertical second laser beam 22 focuses and implicitly cuts the silicon carbide material on the new optical path 21 at the set depth layer position along the new cutting path. Afterwards, the above method is repeated until the processing of all cutting paths of the set depth layer is completed. During the process of forming a complete modified layer on the silicon carbide ingot 10 , the first laser beam 20 only needs to move multiple times to form multiple heating light paths 21 , without the need for a scanning process of multiple burst point scanning, thereby simplifying the equipment complexity of the first laser beam 20 system.

[0057] When carrying out the specific Figure 6 , the newly heated optical path 21 in step 5 can be made parallel to the optical path 21 in step 2, simplifying the movement of the first laser beam 20 and controlling the distribution of the cutting paths for a more uniform distribution. Furthermore, the multiple cutting paths formed in step 7 can be made parallel to each other, with the spacing between any two adjacent cutting paths being equal, ensuring that the crack induced lengths between different cutting paths are substantially the same, facilitating a uniform distribution of cracks throughout the entire set depth layer.

[0058] In addition, in addition to forming a longitudinal temperature gradient in the propagation direction of the optical path 21 as shown above, the first laser beam 20 can also adjust the light intensity distribution of the cross section of the first laser beam 20 so that the light intensity of the cross section of the first laser beam 20 is not uniformly distributed, thereby forming a transverse temperature gradient in the vertical direction of the optical path 21, thereby inducing the crack at the explosion point to grow horizontally at a set depth layer along the direction perpendicular to the optical path 21. Specifically, refer to Figure 5 , the first laser beam 20 can be a Bessel beam. The propagation direction of the first laser beam 20 is the y-axis, and the light intensity on the cross section of the optical path 21 formed by the first laser beam 20 is ρ. Figure 5It can be seen that the light intensity ρ on the cross section of the optical path 21 formed by the first laser beam 20 fluctuates in a wave shape from the center position of the first laser beam 20 to the edge position of the first laser beam 20, thereby forming a transverse temperature gradient with temperature fluctuations on the cross section of the optical path 21. Figure 6 , the darker the color, the higher the temperature, and the lighter the color, the lower the temperature. Figure 7 As shown, the transverse temperature gradient can induce the cracks generated at each explosion point to grow laterally in the direction perpendicular to the optical path 21 within the optical path 21, thereby increasing the length of the cracks at the explosion point extending in the direction perpendicular to the optical path 21, making it easier for cracks on different cutting paths to be quickly connected together. In the above method, by adopting a Bessel beam as the first laser beam 20, not only the cross-sectional size of the first laser beam 20 can be reduced, so as to form a longitudinal temperature gradient with a better distribution effect on an optical path 21 with a smaller cross-sectional area; but also the characteristic of the Bessel beam that the light intensity on the beam cross-sectional area fluctuates in a wave-like manner from the center position of the first laser beam 20 to the edge position of the first laser beam 20 can be utilized to form a transverse temperature gradient with fluctuating temperature on the cross-sectional area of ​​the optical path 21. This transverse temperature gradient can induce cracks generated at each explosion point to grow laterally in the direction perpendicular to the optical path 21 within the optical path 21, thereby increasing the length of the cracks at the explosion point growing in the direction perpendicular to the optical path 21, facilitating the rapid transverse growth and connection of cracks on adjacent cutting paths, thereby appropriately widening the spacing between adjacent cutting paths. In a silicon carbide ingot 10 of the same size, the formation of the modified layer can be completed by emitting fewer optical paths 21, thereby improving processing efficiency.

[0059] After the modified layer is formed in the above manner, a portion of the silicon carbide ingot 10 can be peeled off to form a silicon carbide wafer by stretching or rotating the modified layer as an interface.

[0060] In the various embodiments described above, a first laser beam 20 is incident from the side of the silicon carbide ingot 10 to form a heated optical path 21 at a predetermined depth. Simultaneously, a second laser beam 22 is focused on the optical path 21 formed by the first laser beam 20 and scanned at burst points along the optical path 21. This utilizes the gradually decreasing longitudinal temperature gradient along the optical path 21 formed by the first laser beam 20 to induce cracks at each burst point to grow within the optical path 21 in a direction parallel to the optical path 21. This increases the length of the cracks at the burst points along the direction parallel to the optical path 21, facilitates the rapid extension and connection of cracks between adjacent burst points on the same cutting path, and thus simplifies the difficulty of connecting cracks at adjacent burst points on the same cutting path. In practice, the spacing between different burst points on the same cutting path can be appropriately widened, allowing a cutting path of the same length to be scanned using fewer burst points, thereby improving scanning efficiency. That is, in the stripping method of the present application, the first laser beam 20 and the second laser beam 22 can be carried out simultaneously. The first laser beam 20 is incident from the side of the silicon carbide ingot 10, and is mainly used to form a heating optical path 21 at a set depth layer position of the silicon carbide ingot 10. When the laser beam propagates in the silicon carbide ingot 10, as the silicon carbide material absorbs energy, the energy gradually decreases, so that the silicon carbide material on the optical path 21 has a gradually decreasing longitudinal temperature gradient along the propagation direction of the optical path 21; and the second laser beam 22 is incident from the end face of the silicon carbide ingot 10 to perform a stealth cutting process on the silicon carbide material on the optical path 21. During this process, the longitudinal temperature gradient on the optical path 21 can induce cracks at each explosion point to grow in a direction parallel to the optical path 21 within the optical path 21, thereby increasing the length of the cracks at the explosion point growing in a direction parallel to the optical path 21, so that the cracks between two adjacent explosion points on the same cutting path are quickly extended and connected together, thereby simplifying the difficulty of connecting cracks at adjacent explosion points on the same cutting path. Since the two laser beams are carried out simultaneously and the first laser beam 20 does not need to adopt a scanning process of multiple burst points, the equipment complexity of the first laser beam 20 system can be simplified; the second laser beam 22 can appropriately widen the spacing between different burst points on the same cutting path, so that the cutting path of the same length can be scanned with fewer burst points, thereby improving scanning efficiency, improving processing efficiency, and saving processing costs.

[0061] In addition, the embodiment of the present invention also provides a silicon carbide wafer peeling device, referring to Figure 1 、 Figure 3 and Figure 8The silicon carbide wafer peeling device includes: a stage, a first laser system, and a second laser system. The stage is used to fix the silicon carbide ingot 10 to be cut. The first laser system is used to output a first laser beam 20, and the first laser beam 20 is used to illuminate the silicon carbide ingot 10 from the side, forming a heating optical path 21 at a set depth layer position in the silicon carbide ingot 10, so that the silicon carbide material on the optical path 21 has a gradually decreasing longitudinal temperature gradient along the propagation direction of the optical path 21. The second laser system is used to output a second laser beam 22, and the second laser beam 22 is used to be incident from the end face of the silicon carbide ingot 10 and focused on the optical path 21 at the set depth layer position, forming a blast point to modify the silicon carbide material on the optical path 21. Among them, the second laser system and the stage can also control the focus of the second laser beam 22 to scan along the propagation direction of the optical path 21 or in the opposite direction of the propagation direction, so as to perform explosive point modification on the silicon carbide material at other positions of the optical path 21 to form a cutting path; and the longitudinal temperature gradient can induce cracks at each explosive point to grow in the optical path 21 along a direction parallel to the optical path 21.

[0062] In the above-described scheme, a first laser beam 20 is incident from the side of the silicon carbide ingot 10 to form a heated optical path 21 at a predetermined depth. Meanwhile, a second laser beam 22 is focused on the optical path 21 formed by the first laser beam 20 and scanned at burst points along the optical path 21. The gradually decreasing longitudinal temperature gradient along the optical path 21 formed by the first laser beam 20 is utilized to induce cracks at each burst point to grow within the optical path 21 in a direction parallel to the optical path 21. This increases the length of the cracks at the burst points along the direction parallel to the optical path 21, facilitates the rapid extension and connection of cracks between adjacent burst points on the same cutting path, and thus simplifies the difficulty of connecting cracks at adjacent burst points on the same cutting path. In practice, the spacing between different burst points on the same cutting path can be appropriately widened, so that a cutting path of the same length can be scanned using fewer burst points, thereby improving scanning efficiency. That is, in the stripping method of the present application, the first laser beam 20 and the second laser beam 22 can be carried out simultaneously. The first laser beam 20 is incident from the side of the silicon carbide ingot 10, and is mainly used to form a heating optical path 21 at a set depth layer position of the silicon carbide ingot 10. When the laser beam propagates in the silicon carbide ingot 10, as the silicon carbide material absorbs energy, the energy gradually decreases, so that the silicon carbide material on the optical path 21 has a gradually decreasing longitudinal temperature gradient along the propagation direction of the optical path 21; and the second laser beam 22 is incident from the end face of the silicon carbide ingot 10 to perform a stealth cutting process on the silicon carbide material on the optical path 21. During this process, the longitudinal temperature gradient on the optical path 21 can induce cracks at each explosion point to grow in a direction parallel to the optical path 21 within the optical path 21, thereby increasing the length of the cracks at the explosion point growing in a direction parallel to the optical path 21, so that the cracks between two adjacent explosion points on the same cutting path are quickly extended and connected together, thereby simplifying the difficulty of connecting cracks at adjacent explosion points on the same cutting path. Since the two laser beams are carried out simultaneously and the first laser beam 20 does not need to adopt a scanning process of multiple burst points, the equipment complexity of the first laser beam 20 system can be simplified; the second laser beam 22 can appropriately widen the spacing between different burst points on the same cutting path, so that the cutting path of the same length can be scanned with fewer burst points, thereby improving scanning efficiency, improving processing efficiency, and saving processing costs.

[0063] The above-mentioned loading platform can be set on a three-axis motion platform, referring to Figure 8The three-axis motion stage includes X & Y motion axes and a Z motion axis. The three-axis motion stage can move the stage, thereby causing the first laser beam 20 or the second laser beam 22 to move and scan within a set depth layer of the silicon carbide ingot 10 to be cut. Of course, the first laser beam 20 and the second laser beam 22 can also be moved and scanned within the set depth layer in other ways, for example, using three-axis galvanometers within the first laser system and the second laser system.

[0064] The wavelength parameters, spot parameters, and intensity parameters of the first laser beam 20 output by the first laser system can refer to the description of the above-mentioned method for stripping the silicon carbide wafer, that is, the first laser beam 20 output by the first laser system can be any corresponding method in the above-mentioned method for stripping the silicon carbide wafer. Similarly, the wavelength parameters, spot parameters, and intensity parameters of the second laser beam 22 output by the second laser system can refer to the description of the above-mentioned method for stripping the silicon carbide wafer, that is, the second laser beam 22 output by the second laser system can be any corresponding method in the above-mentioned method for stripping the silicon carbide wafer. In addition, referring to Figure 8 , you can also set up a CCD camera and light source to monitor the status of the explosion point in real time.

[0065] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for peeling a silicon carbide wafer, characterized in that: include: Step 1: Providing a silicon carbide ingot to be cut; Step 2: Using a first laser beam to illuminate the silicon carbide ingot from the side, a heating optical path is formed at a set depth layer position in the silicon carbide ingot, so that the silicon carbide material on the optical path has a gradually decreasing longitudinal temperature gradient along the propagation direction of the optical path; Step 3: using a second laser beam to be incident from the end face of the silicon carbide ingot and focusing on the optical path at the position of the set depth layer to form a blast point to modify the silicon carbide material on the optical path; Step 4: Controlling the focus of the second laser beam to scan along the propagation direction of the optical path or in the opposite direction of the propagation direction to perform explosive point modification on the silicon carbide material at other positions of the optical path to form a cutting path; and the longitudinal temperature gradient can induce cracks at each explosive point to grow in the optical path along a direction parallel to the optical path; Wherein, the first laser beam is a Bessel beam; The light intensity on the cross section of the optical path fluctuates in a wave shape from the center position of the first laser beam to the edge position of the first laser beam, so as to form a transverse temperature gradient with fluctuating temperature on the cross section of the optical path; Furthermore, the transverse temperature gradient can induce cracks generated at each explosion point to grow transversely within the optical path along a direction perpendicular to the optical path.

2. The stripping method according to claim 1, wherein: Also includes: Step 5: According to the method in step 2, the first laser beam is moved to form another new heating optical path at another position of the set depth layer in the silicon carbide ingot; Step 6: According to the method in step 3 and step 4, the second laser beam is focused on the new optical path and is burst and scanned on the new optical path to form a cutting path at the new optical path position; Step seven: According to the method of steps five and six, a plurality of cutting paths are formed at the set depth layer position in the silicon carbide ingot; and the cracks on adjacent cutting paths can grow in a direction perpendicular to the optical path and connect together to form a modified layer at the set depth layer position.

3. The stripping method according to claim 2, wherein: The new heating light path in step five is parallel to the light path in step two.

4. The stripping method according to claim 3, wherein: The multiple cutting lines formed in step seven are parallel to each other, and the distance between any two adjacent cutting lines is equal.

5. The peeling method according to any one of claims 1 to 4, wherein: The wavelength of the first laser beam is 300-400 nm.

6. The peeling method according to any one of claims 1 to 4, wherein: The first laser beam is a parallel beam.

7. The stripping method according to claim 6, wherein: The first laser beam is shaped into a beam with a spot size of 30-50 μm by an aperture.

8. The stripping method according to claim 1, wherein: The second laser beam is incident from the end face of the silicon carbide ingot and focused at the position of the set depth layer to form an elliptical spot, and the major axis of the elliptical spot is perpendicular to the propagation direction of the optical path.

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