Laser processing device, silicon carbide ingot cutting method, and laser processing system

Abstract

The invention discloses a laser processing device, a silicon carbide crystal ingot cutting method and a laser processing system. The laser processing device comprises a laser used for emitting a laser beam with preset laser parameters; the beam splitting element is used for splitting the laser beam into a plurality of sub-beams arranged along a preset direction; the spherical aberration compensation element is used for performing spherical aberration compensation on the plurality of sub-beams and outputting a plurality of spherical aberration compensation beams; and the scanning mechanism is used for focusing the plurality of spherical aberration compensation light beams and cutting the silicon carbide crystal ingot according to a preset cutting path and a preset cutting speed by utilizing the plurality of focused spherical aberration compensation light beams. Spherical aberration compensation is carried out on the sub-beams, the spot size of the focused sub-beams in the silicon carbide crystal ingot in the optical axis direction can be remarkably reduced, the length of a growth area of microcracks is reduced, and then a high-quality silicon carbide wafer is obtained. In addition, the coverage area of the plurality of sub-beams on the surface of the silicon carbide crystal ingot is larger, so that the cutting efficiency is improved.

Description

Technical Field

[0001] The present application relates to the field of laser technology, and in particular to a laser processing device, a method for cutting a silicon carbide ingot, and a laser processing system. Background Art

[0002] With the rapid development of the global semiconductor industry, silicon carbide (SiC) has become a key material for manufacturing high-performance electronic devices due to its excellent physical and chemical properties. The production cost of silicon carbide is very high. In order to reduce the cost, a large silicon carbide ingot needs to be cut into as many thin silicon carbide wafers as possible. However, silicon carbide is extremely hard and brittle, making it very difficult to cut.

[0003] At present, laser cutting technology is usually used to cut SiC ingots (also known as peeling or slicing). When using laser cutting technology to cut SiC ingots, although laser cutting technology brings many significant advantages, it is a challenge to achieve both the cutting efficiency and the cutting quality of SiC ingots. On the one hand, efficiency and quality often restrict each other, and it is necessary to find a proper balance between the two; on the other hand, since SiC ingots are both hard and fragile, ensuring that they are both efficient and maintain high quality during the cutting process increases the difficulty of this challenge. Summary of the invention

[0004] In view of this, the present application provides a laser processing device, a method for cutting a silicon carbide ingot, and a laser processing system, which can take into account both the cutting efficiency and the cutting quality of the silicon carbide ingot.

[0005] In a first aspect, an embodiment of the present application provides a laser processing device, comprising: a laser for emitting a laser beam having preset laser parameters; a beam splitting element for splitting the laser beam into a plurality of sub-beams arranged along a preset direction; a spherical aberration compensation element for performing spherical aberration compensation on the plurality of sub-beams and outputting a plurality of spherical aberration compensation beams; and a scanning mechanism for focusing the plurality of spherical aberration compensation beams and using the plurality of focused spherical aberration compensation beams to cut a silicon carbide ingot at a preset cutting path and a preset cutting speed.

[0006] In some embodiments, the laser processing device also includes: a controller, used to determine the spherical aberration caused by the mismatch between the refractive index of air and the refractive index of the silicon carbide ingot, and determine the spherical aberration compensation phase map required to correct the spherical aberration, wherein the spherical aberration compensation element includes a spatial light modulator, the spatial light modulator is loaded with multiple spherical aberration compensation phase maps, and one spherical aberration compensation phase map is used to perform spherical aberration compensation on a sub-beam.

[0007] In some embodiments, the laser processing device also includes: a controller for controlling the laser to emit a laser beam with preset laser parameters, controlling the spherical aberration compensation element to perform spherical aberration compensation on multiple sub-beams, and controlling a scanning mechanism so that the multiple focused spherical aberration compensation beams cut the silicon carbide ingot at a preset cutting path and a preset cutting speed.

[0008] In some embodiments, the laser processing device also includes: a controller, wherein the scanning mechanism includes a focusing optical element and a three-axis translation stage for carrying the silicon carbide ingot, the focusing optical element is used to focus multiple spherical aberration compensation beams to obtain multiple focused spherical aberration compensation beams, and the controller controls the movement of the three-axis translation stage so that the multiple focused spherical aberration compensation beams cut the silicon carbide ingot at a preset cutting path and a preset cutting speed.

[0009] In some embodiments, the laser processing device also includes: a controller, wherein the scanning mechanism includes a focusing optical element and a galvanometer group, the focusing optical element is used to focus multiple spherical aberration compensation beams to obtain multiple focused spherical aberration compensation beams, and the controller controls the deflection angle of the galvanometer group so that the multiple focused spherical aberration compensation beams can cut the silicon carbide ingot at a preset cutting path and a preset cutting speed.

[0010] In some embodiments, the beam splitting element comprises a Dammann grating.

[0011] In some embodiments, an angle between the preset direction and a first direction perpendicular to the preset cutting path is greater than or equal to 0° and less than or equal to 45°.

[0012] In some embodiments, the preset cutting speed is 15 mm / s to 50 mm / s, and the spacing between adjacent laser processing lines in the preset cutting path is 30 μm to 50 μm.

[0013] In some embodiments, the laser comprises a femtosecond laser, and the preset laser parameters comprise: a pulse width of 190 fs to 350 fs, a repetition frequency of 50 KHz to 500 KHz, and an average power of 1 W to 2 W.

[0014] In a second aspect, a method for cutting a silicon carbide ingot is provided, comprising: determining spherical aberration caused by the mismatch between the refractive index of air and the refractive index of the silicon carbide ingot, and determining a spherical aberration compensation phase diagram required for correcting the spherical aberration; controlling a spatial light modulator to load a plurality of spherical aberration compensation phase diagrams, and based on the plurality of spherical aberration compensation phase diagrams, performing spherical aberration compensation on a plurality of sub-beams arranged along a preset direction, and outputting a plurality of spherical aberration compensation beams, wherein a spherical aberration compensation phase diagram is used to perform spherical aberration compensation on a sub-beam; controlling a plurality of focused spherical aberration compensation beams to move on the silicon carbide ingot at a preset cutting path and a preset cutting speed, and modifying the interior of the silicon carbide ingot to complete the cutting of the silicon carbide ingot, wherein the plurality of focused spherical aberration compensation beams are obtained after focusing the plurality of spherical aberration compensation beams.

[0015] In some embodiments, an angle between the preset direction and a first direction perpendicular to the preset cutting path is greater than or equal to 0° and less than or equal to 45°.

[0016] In some embodiments, the spacing between adjacent laser processing lines in the preset cutting path is 30 μm to 50 μm, and the preset cutting speed is 15 mm / s to 50 mm / s.

[0017] In some embodiments, the cutting method also includes: controlling the laser to output a laser beam having preset laser parameters, wherein the laser beam is split by a beam splitting element to obtain a plurality of sub-beams, and the preset laser parameters include a pulse width of 190fs to 350fs, a repetition frequency of 50KHz to 500KHz, and an average power of 1W to 2W.

[0018] In a third aspect, a laser processing system is provided, comprising: a memory and a processor, wherein the memory stores executable code, and the processor is configured to execute the executable code to implement the method for cutting a silicon carbide ingot as described in any embodiment of the second aspect.

[0019] In the laser processing scheme of the present application, spherical aberration compensation is performed on multiple sub-beams, which can significantly reduce the spot size of each focused sub-beam in the direction of the optical axis inside the silicon carbide ingot, and reduce the length of the growth area of ​​the microcracks generated along the direction of the optical axis during the processing, thereby achieving more precise control when laser cutting the silicon carbide ingot, and then obtaining high-quality silicon carbide wafers. In addition, multiple sub-beams are used to cut the silicon carbide ingot. Compared with a single-focus Gaussian beam, the coverage area of ​​multiple sub-beams on the surface of the silicon carbide ingot is larger, which improves the cutting efficiency, also known as the slicing efficiency. Therefore, the processing of silicon carbide ingots has a double improvement in efficiency and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1It is a structural schematic diagram of a laser processing device provided in one embodiment of the present application.

[0021] Figure 2 It is a schematic structural diagram of a laser processing device provided in another embodiment of the present application.

[0022] Figure 3 It is a schematic diagram of the structure of the Dammann grating provided in one embodiment of the present application under a birefringence microscope.

[0023] Figure 4 It is a schematic diagram of the distribution of multiple sub-beams provided in one embodiment of the present application.

[0024] Figure 5 It is a schematic diagram of a spherical aberration compensation phase diagram provided in an embodiment of the present application.

[0025] Figure 6 It is a schematic diagram of the spot morphology of a focused spherical aberration compensated light beam and a focused light beam without spherical aberration compensation provided by an embodiment of the present application in the XZ plane inside a silicon carbide ingot.

[0026] Figure 7 It is a schematic diagram of cutting paths of multiple spherical aberration compensation beams on the XY plane of a silicon carbide ingot provided by an embodiment of the present application.

[0027] Figure 8 This is a microscope image of a silicon carbide ingot after cutting provided in an embodiment of the present application.

[0028] Fig. 9 It is a schematic flow chart of a method for cutting a silicon carbide ingot provided in one embodiment of the present application.

[0029] Fig.10 It is a schematic diagram of the structure of a silicon carbide ingot cutting system provided in one embodiment of the present application.

[0030] Fig.11 is a block diagram of a laser processing system provided in one embodiment of the present application. DETAILED DESCRIPTION

[0031] The exemplary embodiments will be described in detail below, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are only examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims.

[0032] The terms used in this application are only for the purpose of describing specific embodiments, and are not intended to limit the application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms, unless other meanings are clearly indicated below. It should also be understood that the term "and / or" used in this article refers to and includes any or all possible combinations of one or more associated listed items. It should also be understood that the word "if" used in this article, depending on the context, can be interpreted as "at the time of" or "when" or "in response to determining".

[0033] In the current laser cutting technology, in order to improve the cutting efficiency of silicon carbide ingots, beam technologies such as multi-focus beams, flat-top beams or Bessel beams are usually used. Although these beams can improve the cutting efficiency to a certain extent, they cannot always ensure the cutting quality. This is because there are still some technical difficulties in the laser cutting technology of silicon carbide ingots that have not been completely overcome. For example, the range of laser-induced microcracks is too large or the thickness of the chemical decomposition layer of silicon carbide under the action of laser is difficult to control. These problems will cause a certain degree of roughness on the surface of the silicon carbide wafer, thereby reducing the quality of the silicon carbide wafer. Therefore, although these beam technologies have played a role in improving cutting efficiency, further technical breakthroughs and optimizations are still needed to ensure cutting quality.

[0034] However, it should be noted that the present application is not limited to the cutting of silicon carbide ingots, but is also applicable to the cutting of other brittle and hard inorganic non-metallic materials or semiconductor materials, such as glass and silicon wafers. These materials will encounter similar problems as the cutting of silicon carbide ingots during the cutting process, such as the inability to guarantee both cutting quality and cutting efficiency, the range of laser-induced microcracks being too large, or the thickness of the chemical decomposition layer of silicon carbide under the action of laser being difficult to control. Therefore, the solution proposed in the present application has wide applicability and can provide technical support for the precision cutting of a variety of hard and brittle materials.

[0035] For ease of understanding, the generation of microcracks and the generation of chemical decomposition layers will be briefly introduced below.

[0036] The laser is focused inside the silicon carbide. Due to the accumulation of heat, a gradient heat-affected zone is formed inside the silicon carbide. The thermal stress on the silicon carbide in the heat-affected zone is different. Therefore, microcracks are formed due to uneven force.

[0037] Chemical decomposition layers usually refer to chemical changes in silicon carbide under laser irradiation, resulting in the decomposition of the material into new phases of its constituent elements or compounds. For example, laser-induced phase separation can cause silicon carbide to decompose into amorphous silicon and amorphous carbon, or even further transform into multilayer graphene. The formation of such decomposition layers usually involves the interaction of the laser with the material, such as a high-power laser beam focused on the surface of the material, resulting in rapid heating and phase change in the local area.

[0038] The formation of a chemically decomposed layer may also be accompanied by the generation of microcracks, which can form within the material, affecting its integrity and mechanical properties.

[0039] Research has found that both the laser beam shape and the heat diffusion of the laser may cause microcracks to spread around. For example, the non-uniformity of the laser beam shape will cause greater internal damage to the wafer during the cutting process of the silicon carbide ingot, resulting in a certain degree of roughness on the surface of the silicon carbide wafer, which in turn affects the quality of the silicon carbide wafer. Therefore, in order to prevent the microcracks from spreading around, the generation of microcracks should be concentrated on the laser scanning path (i.e., the cutting path described below) as much as possible. However, faced with a large number of choices for beam shapes and laser parameters, which beam shape and laser parameter laser to use for cutting silicon carbide ingots has become a key factor in determining the cutting effect.

[0040] After a series of further experimental explorations and theoretical studies, it was found that reducing the spot size of the focused beam along the optical axis (also known as the depth of focus) can effectively control the growth of microcracks in the silicon carbide ingot and accurately regulate the thickness of the chemical decomposition layer under the action of the laser. The key to this discovery is that shortening the beam spot size can reduce the length of the growth area of ​​the microcracks generated along the optical axis during the processing process, thereby achieving more precise control when laser cutting silicon carbide ingots, and then obtaining high-quality silicon carbide wafers.

[0041] Therefore, in the laser processing scheme of the present application, spherical aberration compensation is performed on multiple sub-beams, which can significantly reduce the spot size of each focused sub-beam inside the silicon carbide ingot along the optical axis direction, and reduce the length of the growth area of ​​the microcracks generated along the optical axis during the processing, thereby achieving more precise control when laser cutting the silicon carbide ingot, and then obtaining high-quality silicon carbide wafers. In addition, multiple sub-beams are used to cut the silicon carbide ingot. Compared with a single-focus Gaussian beam, the coverage area of ​​multiple sub-beams on the surface of the silicon carbide ingot is larger, which improves the cutting efficiency, also known as the slicing efficiency. Therefore, the processing of silicon carbide ingots brings a double improvement in efficiency and quality.

[0042] Combine the following Figure 1 and 2, the laser processing device provided in the embodiment of the present application is illustrated in more detail.

[0043] like Figure 1 and 2 As shown, the laser processing device includes a laser 110, a beam splitter 160, a spherical aberration compensation element 170 and a scanning mechanism arranged in sequence on an optical path. The laser 110 is used to emit a laser beam with preset laser parameters; the beam splitter 160 is used to split the laser beam into a plurality of sub-beams arranged along a preset direction; the spherical aberration compensation element 170 is used to perform spherical aberration compensation on the plurality of sub-beams and output a plurality of spherical aberration compensation beams; the scanning mechanism is used to focus the plurality of spherical aberration compensation beams, and use the plurality of focused spherical aberration compensation beams to cut the silicon carbide ingot at a preset cutting path and a preset cutting speed.

[0044] by Figure 1 and 2 As an example, the specific composition details of the scanning mechanism are shown.

[0045] In one example, if Figure 1 As shown, the scanning mechanism includes a focusing optical element 181 and a three-axis translation stage 183 for carrying the silicon carbide ingot 190 .

[0046] The focusing optical element 181 includes a sleeve lens 1811 and an objective lens 1812. The combination of the sleeve lens 1811 and the objective lens 1812 is used because the light field area of ​​the multiple spherical aberration compensation beams is relatively large, but the entrance pupil of the objective lens 1812 is relatively small, so the sleeve lens 1811 for pre-focusing is arranged before the objective lens 1812, and the objective lens 1812 is used to focus the multiple spherical aberration compensation beams into the interior of the silicon carbide ingot 190.

[0047] However, it should be noted that the specific composition of the focusing optical element 181 is not limited to the elements listed above. Those skilled in the art can select and adjust the composition of the focusing optical element 181 according to actual application requirements. For example, the focusing optical element 181 only includes the objective lens 1812, and the focusing optical element 181 only needs to meet the focusing function.

[0048] In addition, the scanning mechanism may also include other components, for example, a dichroic mirror 182 located between the sleeve lens 1811 and the objective lens 1812. The three-axis translation stage 183 is located behind the objective lens 1812. However, it should be noted that the specific composition of the scanning mechanism is not limited to the components listed above, and those skilled in the art can select and adjust the composition of the scanning mechanism according to actual application requirements.

[0049] On this basis, the laser processing device further includes: a controller 109 and a charge-coupled device (CCD) 184 located after the dichroic mirror 182. The dichroic mirror 182 is also used to allow the imaging light source of the CCD 184 to enter the focusing optical element 181; the CCD 184 is used to perform imaging detection on the implementation process of the laser processing through the dichroic mirror 182; the controller 109 is used to control the repetition frequency, pulse width, pulse energy and other parameters of the laser beam emitted by the laser 110, and is also used to control the movement of the three-axis translation stage 183, and control the imaging of the CCD 184.

[0050] The controller 109 controls the movement of the three-axis translation stage 183 so that the multiple focused spherical aberration compensation light beams obtained after being focused by the focusing optical element 181 move on the silicon carbide ingot 190 at a preset cutting path and a preset cutting speed. The preset cutting speed is 15 mm / s to 50 mm / s. Preferably, the preset cutting speed is 25 mm / s.

[0051] The controller 109 controls the three-axis translation stage 183 to achieve sub-micron level precise position adjustment, thereby improving cutting accuracy.

[0052] In another example, if Figure 2 As shown, the scanning mechanism includes a focusing optical element 181 and a galvanometer group (which includes a galvanometer 1851 and a galvanometer 1852).

[0053] In addition, the scanning mechanism includes not only Figure 2 The elements shown in the figure may also include other elements not shown in the figure. Figure 2 The components shown in the figure are Figure 1 For example, the scanning mechanism also includes a sleeve lens 1811 and an objective lens 1812 (which also constitutes Figure 2 The scanning mechanism includes a focusing optical element 181 in the scanning apparatus, and a dichroic mirror 182 located between the sleeve lens 1811 and the objective lens 1812. The three-axis translation stage 183 is located after the objective lens 1812. However, it should be noted that the specific composition of the scanning mechanism is not limited to the above-mentioned components, and those skilled in the art can select and adjust the composition of the scanning mechanism according to actual application requirements.

[0054] On this basis, the laser processing device further includes: a controller 109 and a charge-coupled device (CCD) 184 located after the dichroic mirror 182. The dichroic mirror 182 is also used to allow the imaging light source of the CCD 184 to enter the focusing optical element 181; the CCD 184 is used to perform imaging detection on the implementation process of the laser processing through the dichroic mirror 182; the controller 109 is used to control the repetition frequency, pulse width, pulse energy and other parameters of the laser beam emitted by the laser 110, and is also used to control the deflection angle of the galvanometer group, and control the imaging of the CCD 184.

[0055] The controller 109 controls the deflection angle of the galvanometer group so that the multiple focused spherical aberration compensation light beams obtained after being focused by the focusing optical element 181 move on the silicon carbide ingot 190 at a preset cutting path and a preset cutting speed. The preset cutting speed is 15 mm / s to 50 mm / s. Preferably, the preset cutting speed is 25 mm / s.

[0056] The controller 109 controls the galvanometer group to achieve high-speed and high-precision light beam scanning, and then cooperates with the objective lens to focus the light field, thereby improving the cutting efficiency and cutting accuracy.

[0057] It should be understood that Figure 2 The dotted lines in the figure outline the complete area that can be covered by multiple spherical aberration compensation beams under the deflection of the galvanometer group. Figure 2 The maximum range that multiple spherical aberration compensation beams can reach under the control of the galvanometer group is marked in Figure 2 The figure shows the complete spatial range that can be reached by multiple spherical aberration compensation beams under the dynamic deflection of the galvanometer group.

[0058] It should be noted that Figure 1 and 2 The black thick lines are used schematically to represent the elements that the controller 109 can control. Those skilled in the art can select and adjust the elements that the controller 109 can control according to actual application requirements. For example, Figure 2 In the embodiment, the controller 109 can also control the movement of the three-axis translation stage 183, that is, the galvanometer group and the three-axis translation stage 183 work together to enable multiple focused spherical aberration compensation beams to move on the silicon carbide ingot 190 at a preset cutting path and a preset cutting speed.

[0059] It should be understood that the reference to A being before or after B in this document means that A is before or after B along the propagation direction of light.

[0060] exist Figure 1 and Figure 2On the basis of this, the laser processing device also includes: a reflector 153 located between the beam splitting element 160 and the spherical aberration compensation element 170 and arranged in sequence on the optical path, a lens group (which includes lens 154 and lens 156, which constitute a 4f system) and an aperture 155.

[0061] The reflector 153 is used to reflect the multiple sub-beams obtained after being split by the beam splitting element 160 to the lens group; the lens group is used to expand or shrink the multiple sub-beams; the aperture 155 is used to perform spatial filtering on the multiple sub-beams to improve the beam splitting quality.

[0062] The process of splitting the laser beam is described in detail below.

[0063] In one example, when the beam splitting element 160 is a Dammann grating, Figure 1 and 2 As shown, the laser processing device also includes: an angle stabilization component 120, a power adjustment component 130, a beam expander 140, a reflector 151 and a 1 / 2 wave plate 152, which are located between the laser 110 and the beam splitting element 160 and arranged in sequence on the optical path. The angle stabilization component 120 is used to maintain the directional stability of the laser beam during the collimation process, that is, to control the angle stability of the laser (also known as the stability of the laser directivity) to ensure the collimation stability of the output optical path. The angle stabilization component 120 has a feedback device inside to control the direction of the laser in real time; the power adjustment component 130 is used to maintain the stability of the laser power, for example, to adjust the laser power in a range of 0.3% to 99% under a specific polarization; the beam expander 140 is used to expand the spot of the laser beam emitted by the laser 110 to a preset multiple, for example, 2 to 6 times; the reflector 151 is used to reflect the laser beam expanded by the beam expander 140 to the 1 / 2 wave plate 160; the 1 / 2 wave plate 152 is used to change the polarization direction of the laser beam so that the laser beam is incident on the beam splitter 160 with a suitable polarization direction.

[0064] The arrangement of the angle stabilizing component 120 and the power regulating component 130 can make the output of the laser parameters more stable, so as to ensure the stable generation of micro cracks inside the subsequent silicon carbide ingot.

[0065] The angle stabilization component 120 may include a deflecting mirror and a closed-loop controller. The closed-loop controller is an electronic system for continuously monitoring the deviation between the laser beam and the target position and controlling the deflecting mirror to adjust to maintain the stability of the laser beam. However, the embodiment of the present application does not limit the specific composition of the angle stabilization component, and those skilled in the art may make different choices according to actual application requirements.

[0066] The power regulating component 130 may include a laser power controller or an optical power regulator / limiter, etc. Those skilled in the art may make different choices according to actual application requirements.

[0067] The purpose of setting the 1 / 2 wave plate 152 before the beam splitting element 160 is to utilize the characteristic that the phase difference between two adjacent strip regions of the Dammann grating is π to achieve a more uniform beam splitting effect. When the incident laser beam is linearly polarized light, the uniformity of the beam splitting reaches the best state, and the diffraction efficiency can be close to the theoretical value. Therefore, the polarization direction of the incident laser beam is adjusted by the 1 / 2 wave plate 152, thereby optimizing the beam splitting performance.

[0068] In the present application, the transmittance of the Dammann grating is greater than 97%, the beam splitting mode is 1×7, the maximum beam splitting angle is 2°, and the beam splitting uniformity is greater than 85%. However, it should be noted that the specific parameter values ​​of the Dammann grating used in the present application are not limited to the parameter values ​​listed above. Different parameter values ​​can be set for different application requirements, for example, the beam splitting mode is 1×5.

[0069] It should be understood that if the beam splitting element 160 has no specific requirements on the polarization state of the light, then in this case, it can be omitted. Figure 1 and Figure 2 The 1 / 2 wave plate 152 shown in FIG.

[0070] The Dammann grating will be described in detail below. Figure 3 As shown, it shows the structure of the Dammann grating under a birefringence microscope.

[0071] Dammann grating is a diffractive optical element that achieves uniform beam splitting. Its structure consists of a series of position-encoded binary phase (0-π) structures. This design enables the Dammann grating to achieve uniform beam splitting, that is, by controlling the position of the binary phase change point within one period, it is easy to achieve equal light intensity of the multi-order diffraction spot in the far field of the laser. The Dammann grating has unique advantages such as flat structure, high diffraction efficiency and high beam splitting ratio. In the field of femtosecond laser processing, these advantages enable the Dammann grating to provide multi-focus laser beam shaping and improve laser processing efficiency, thereby significantly improving the efficiency and effect of laser processing.

[0072] In the present application, the Dammann grating has a typical sandwich structure, in which the fast axis orientation of the liquid crystal molecules in the liquid crystal polymer (LCP) layer presents a binary periodic change from 0 to 90° along the x-axis. This design provides a λ / 2 delay across the entire device plane, making the Dammann grating a single-wavelength device. A significant advantage of the Dammann grating over conventional gratings and cascaded grating beam splitters is that it can achieve odd-number beam splitting and beam splitting with a larger number of points using only a single-chip structure, while ensuring that the spacing and intensity between each beam splitting spot are equal.

[0073] In the Dammann grating, the splitting angle θ is defined as the maximum diffraction angle of the outgoing split beam spot, and the separation angle δ refers to the angle between two adjacent split beam spots. According to the grating diffraction formula: dsinδ = mλ, where d is the period of the Dammann grating, m is the order of the diffraction spot, and λ is the operating wavelength. For a standard one-dimensional Dammann grating, the splitting angle θ refers to the diffraction angle corresponding to the edge diffraction order spot, that is, Figure 4 There is an approximate relationship between θ and the separation angle δ: θ≈6δ, which means that the beam splitting angle θ is approximately six times the separation angle δ. This approximate relationship helps to predict and calculate the distribution of the output light spot when designing and applying the Dammann grating.

[0074] like Figure 4 As shown, when the laser beam 11 passes through the Dammann grating 160 at a splitting angle θ, n sub-beams can be generated, where n is greater than 1. Each sub-beam has its own focus, so when the n sub-beams are combined together, they together form a Gaussian light field with multiple focuses. In other words, through the Dammann grating, a single Gaussian beam is split into a Gaussian light field with multiple focuses, thereby achieving a multi-focus distribution of the beam.

[0075] The above advantages of Dammann grating make the uniformity of multiple sub-beams better and the wavefront consistency higher. In particular, each sub-beam presents the characteristics of a Gaussian beam, which greatly facilitates the calculation process of subsequent spherical aberration correction. In addition, due to the good uniformity of multiple sub-beams, microcracks will be generated evenly when cutting silicon carbide ingots, and the range of microcrack generation will be more controllable, thereby reducing losses.

[0076] The process of performing spherical aberration compensation on the sub-beam is described in detail below.

[0077] In one example, the spherical aberration compensation element 170 may be a spatial light modulator (SLM). A spatial light modulator is a programmable beam shaping device. When the multiple sub-beams output from the beam splitting element 160 pass through the target surface of the spatial light modulator, the liquid crystal layer changes the deflection direction of the liquid crystal molecules under the control of the electric field, thereby modulating the phases of the multiple sub-beams. Subsequently, the controller 109 precisely controls the electric field so that the multiple sub-beams are loaded with preset phase information, and finally realizes the output of multiple spherical aberration compensation beams.

[0078] The spatial light modulator precisely controls the light field by loading preset phase information, thereby changing the focusing shape of multiple sub-beams inside the silicon carbide.

[0079] In the present application, spherical aberration compensation is performed on multiple sub-beams by a spatial light modulator, and the spatial light modulator is loaded with Figure 5 The multiple spherical aberration compensation phase diagrams shown (including preset phase information) are used to compensate for the spherical aberration of a sub-beam to optimize the focusing effect of the beam. The spherical aberration compensation phase diagram describes the laser parameters that need to be adjusted during the spherical aberration correction process in the form of phase.

[0080] although Figure 5 Only 7 spherical aberration compensation phase diagrams are shown in the figure, but those skilled in the art should understand that as the number of sub-beams increases, the number of spherical aberration compensation phase diagrams is not limited to 7. In fact, each sub-beam corresponds to an exclusive spherical aberration compensation phase diagram to achieve precise control of each sub-beam.

[0081] By combining the Dammann grating and spatial light modulator, the efficiency and quality of cutting SiC ingots can be significantly improved. This joint application method takes advantage of the uniformity and wavefront consistency of the Dammann grating and the flexible wavefront control capability of the spatial light modulator, thus achieving precise and efficient cutting of SiC ingots.

[0082] In addition, other optical elements are arranged after the spatial light modulator, including but not limited to the tube lens 1811, the dichroic mirror 182, the objective lens 1812 and the galvanometer group. These optical elements will also perform Fourier transform on the spherical aberration compensation light beam to dynamically control the light field, thereby improving the shape of the laser focusing inside the silicon carbide ingot.

[0083] It is mentioned above that the spatial light modulator can load multiple spherical aberration compensation phase maps, but how are these spherical aberration compensation phase maps generated? In fact, the spherical aberration compensation phase map is the result of the spherical aberration correction process. Before loading these spherical aberration compensation phase maps, the spherical aberration compensation amount required for each sub-beam is also determined (i.e., the spherical aberration generated based on the mismatch between the refractive index of air and the refractive index of the silicon carbide ingot) in order to accurately compensate for the spherical aberration of each sub-beam. Next, the specific process of spherical aberration correction and how to obtain these spherical aberration compensation phase maps will be described in detail.

[0084] It should be understood that spherical aberration compensation and spherical aberration correction are two different steps. Spherical aberration correction is performed before spherical aberration compensation, and its purpose is to determine the spherical aberration compensation amount required for each sub-beam and determine the spherical aberration compensation phase map required to correct the spherical aberration compensation amount. On the other hand, spherical aberration compensation is to implement the corresponding spherical aberration compensation amount for each sub-beam on the basis of spherical aberration correction, that is, to perform spherical aberration compensation on each sub-beam using the spherical aberration compensation phase map determined by the spherical aberration correction process.

[0085] During the laser cutting process, the laser beam (i.e., each sub-beam described above) passes through two different media (i.e., air and SiC ingot). Due to the difference in the refractive index of air and SiC ingot, when the laser beam is focused inside the SiC ingot, the spot shape will change due to the mismatch in refractive index.

[0086] Research has found that changes in the spot shape due to refractive index mismatch will cause microcracks to spread around, resulting in a certain degree of roughness on the surface of the silicon carbide wafer, which in turn affects the quality of the silicon carbide wafer.

[0087] Therefore, in order to reduce the impact of refractive index mismatch on the spot morphology and prevent microcracks from spreading around, spherical aberration correction technology can be used to optimize beam focusing and thus improve cutting quality.

[0088] Next, a spherical aberration correction method will be introduced in the form of an example. This method is based on the Zernike polynomial phase difference and aims to correct the wavefront distortion caused by the refractive index mismatch to correct the spot shape. In specific implementation, the preset phase information is loaded through the spatial light modulator so that the spot undergoes the expected morphological change before entering the silicon carbide ingot, thereby achieving spherical aberration compensation.

[0089] When the laser beam passes through the air with a refractive index of n1 and the silicon carbide ingot with a refractive index of n2, the laser beam will generate a wavefront with deviation through the objective lens. The wavefront deviation function is expressed as Where d represents the depth at which the light spot is focused in the SiC ingot, and ρ represents the normalized radius coordinate, defined as ρ = sinφ1 / sinα = sinφ2 / sinβ, where φ1 and φ2 represent the incident angle and the exit angle of the laser beam at the interface between air and SiC ingot, respectively, and α and β represent the maximum incident angle and the maximum exit angle, respectively. The numerical aperture of the objective lens is NA, defined as NA = n1sinα = n2sinβ. When cutting SiC ingots, if the laser beam needs to be focused at a specific depth inside the SiC ingot, then It is equal to the optical path difference between the laser beam in the air and the silicon carbide ingot, that is:

[0090]

[0091] Among them, L2=d / cosφ2, L1=L2cos(φ1-φ2).

[0092] According to Fresnel's law of refraction, we can conclude that: n1sinφ1=n2sinφ2.

[0093] Substituting the relationships L2=d / cosφ2, L1=L2cos(φ1―φ2) and n1sinφ1=n2sinφ2 into Formula 1, we get:

[0094]

[0095] Then, substituting ρ = sinφ1 / sinα = sinφ2 / sinβ into Formula 2, we can obtain:

[0096] The spot deformation caused by focusing the laser beam inside the silicon carbide ingot will cause wavefront deviation. This deviation, combined with the defocus pupil function, can be expressed as:

[0097]

[0098] Where P(ρ) is the radius-normalized pupil function. When ρ≤1, P(ρ)=1; otherwise, P(ρ)=0. Definition At this time, the out-of-focus spread function is:

[0099]

[0100] Where k = 2π / λ, λ represents the wavelength of the laser; v and u represent the normalized horizontal coordinate and normalized vertical coordinate of the laser beam, respectively, and are defined as:

[0101]

[0102] Where r and z represent the lateral and longitudinal displacements of the light spot at the focus, i.e., the defocus distance caused by the refractive index mismatch. Based on these displacement parameters, the light intensity distribution in the focal area inside the silicon carbide ingot can be defined as: I(v,u,d) = |h(v,u,d)| 2 .

[0103] In order to correct the spot shape, the spatial light modulator is loaded with a spherical aberration compensation phase diagram. This design allows the light field to be pre-loaded with a compensatory spherical aberration (i.e., spherical aberration caused by the mismatch between the refractive index of air and the refractive index of the silicon carbide ingot) before entering the silicon carbide ingot. In order to determine the above-mentioned compensatory spherical aberration, the pre-corrected spherical aberration (i.e., the spherical aberration calculated based on the refractive index of air and the refractive index of the silicon carbide ingot) will be determined first. The pre-corrected spherical aberration can be expanded by the zero-order Zernike polynomial, which is specifically expressed as:

[0104]

[0105] in, A n,0 =B n (α)―B n (β),

[0106] In the zero-order Zernike polynomial, when n = 0, 2, 4, 6, Z n,0 (ρ) respectively correspond to the following expressions:

[0107] When n=0, Z 0,0 (ρ) = 1, indicating a constant, which has no effect on the focusing shape of the laser inside the silicon carbide ingot;

[0108] When n=2, Indicates defocus, which will cause the focused spot inside the silicon carbide ingot to shift in the axial direction, but has no effect on the size of the spot;

[0109] When n=4, It reflects the influence of aberration on the laser morphology inside the silicon carbide ingot, which causes the energy density of the light spot to change;

[0110] When n=6, Represents secondary spherical aberration, caused by refractive index mismatch, which has a significant effect on the focal position and spot size of the laser beam.

[0111] In order to correct the influence of spherical aberration caused by refractive index mismatch on the spot shape, the wavefront deviation function is modified. The core goal of this correction is to optimize the pupil function and make its value as close to 1 as possible, so as to ensure the optimal beam quality. To achieve this goal, the phase information loaded by the spatial light modulator is a reverse Zernike polynomial:

[0112]

[0113] Where N represents the spherical aberration compensation level. When N = 0, only defocus correction is performed, that is, only the change in the laser focus position is adjusted, and the spherical aberration is not corrected; when N ≥ 1, the spherical aberration caused by the refractive index mismatch is corrected, which includes not only the correction of defocus, but also the correction of the laser spot shape; as the N value increases, higher-order spherical aberration can be corrected, thereby achieving a more refined and comprehensive correction of the laser focus spot shape.

[0114] In order to accurately compensate for the spherical aberration caused by the refractive index mismatch and correct the spot morphology, a compensation method based on the inverse Zernike polynomial is adopted in this application. Subsequently, the spherical aberration compensation series in the Zernike polynomial is iteratively optimized by the GCS algorithm (Gerchberg-Saxton (GS) algorithm). The optimized solution is used to generate the corresponding inverse Zernike polynomial phase distribution in the polar coordinate system, which is then loaded onto the spatial light modulator to achieve spherical aberration compensation for the laser focal spot.

[0115] It should be understood that the spherical aberration calculated based on the refractive index of air and the refractive index of the silicon carbide ingot is expanded by the zero-order Zernike polynomial, while the spherical aberration generated by the mismatch between the refractive index of air and the refractive index of the silicon carbide ingot is expanded by the reverse Zernike polynomial.

[0116] Through the above precise spherical aberration correction process, each sub-beam generates a corresponding spherical aberration compensation phase map, such as Figure 5 As shown, these spherical aberration compensation phase images are loaded into the spatial light modulator to achieve accurate compensation for the spherical aberration of each sub-beam.

[0117] It should be noted that the specific composition of the above-mentioned laser processing device is not limited to Figure 1 and 2 The above-listed components are shown in the figure. Those skilled in the art can select and adjust the composition of the laser processing device according to actual application requirements. For example, more reflectors or fewer reflectors can be used. In addition, the order of the components included in the laser processing device is not fixed. Those skilled in the art can select and adjust the components according to actual application requirements. Figure 1 and 2 Adjust the order of components shown in the figure.

[0118] Combine the following Figure 6 and 7, a spherical aberration compensated beam and a non-spherical aberration compensated beam are compared to better illustrate the significant advantages of using a spherical aberration compensated beam in the process of cutting silicon carbide ingots. Specifically, the spherical aberration compensated beam can significantly improve the cutting quality and improve the cutting efficiency.

[0119] like Figure 6 As shown in FIG. 1 , it shows the light field distribution of the focused beam on the XZ plane inside the silicon carbide ingot. It can be seen that along the Z axis (optical axis), the focused spherical aberration compensation beam (shown in FIG. 1 ) is Figure 6 ) compared to the focused beam without spherical aberration compensation (shown on Figure 6 Compared with the focused beam without spherical aberration compensation, the spot size of the focused spherical aberration compensated beam along the Z-axis direction is reduced by 70% to 80%.

[0120] Since the focused spherical aberration compensation beam has a smaller spot size along the direction of the optical axis than the focused beam without spherical aberration compensation, this means that the action depth of the focused spherical aberration compensation beam inside the silicon carbide ingot 190 is shallower, that is, the thickness of the loss layer where the microcracks are located becomes thinner, which not only reduces the length of the growth area of ​​the microcracks generated along the direction of the optical axis during the processing, thereby more accurately controlling the growth area of ​​the microcracks, but also effectively controls the thickness of the chemical decomposition layer under the action of the laser, and can also improve the utilization rate of the silicon carbide ingot (that is, reduce processing losses), because the thinner the thickness of the loss layer where the microcracks are located, the more silicon carbide wafers can be cut from a whole silicon carbide ingot.

[0121] like Figure 7 As shown, the preset direction D and the first direction perpendicular to the preset cutting path (as shown by the horizontal arrow line) (ie, Figure 7 The angle between the multiple focused spherical aberration compensation beams 11-1 ... 11-7 is equal to 0° along the cutting plane of the silicon carbide ingot (ie, Figure 7 The spherical aberration compensation beams 11-1 ... 11-7 are combined together to increase the spot size in the Y-axis direction by 280% to 320% compared to the single-focus beam without spherical aberration compensation.

[0122] Figure 7Only one possible implementation is shown, in which the preset direction D is perpendicular to the preset cutting path and the angle between the preset direction D and the Y-axis direction is 0°. In this implementation, compared with a single-focus Gaussian beam without spherical aberration compensation, after the multiple focused spherical aberration compensation beams 11-1…11-7 are combined together, the spot size in the Y-axis direction is significantly expanded, so the interval between adjacent laser processing lines is correspondingly increased, that is, the length of the laser processing line is longer, which means that the number of times the laser acts on the silicon carbide ingot 190 (that is, the number of scans) is reduced, which not only reduces the influence of thermal stress and thermal shock waves during multi-pulse deposition, thereby more accurately controlling the growth area of ​​microcracks, but also effectively controls the thickness of the chemical decomposition layer under the action of the laser, and can also improve the cutting efficiency.

[0123] But it should be noted that Figure 7 The above is only a schematic illustration of a possible implementation in which the preset direction D is perpendicular to the preset cutting path (i.e., the angle between the preset direction D and the first direction is 0°). In fact, the preset direction D may also intersect with the preset cutting path, but need not be perpendicular, i.e., the angle between the preset direction D and the first direction is greater than 0° and less than or equal to 45°. Figure 7 The horizontal direction is the X-axis and the vertical direction is the Y-axis for example. However, the horizontal direction may be the Y-axis and the vertical direction may be the X-axis.

[0124] Therefore, in the laser processing scheme of the present application, spherical aberration compensation is performed on multiple sub-beams arranged along a preset direction, which can significantly reduce the spot size of each focused sub-beam in the direction of the optical axis inside the silicon carbide ingot, and reduce the length of the growth area of ​​the microcracks generated along the direction of the optical axis during the processing, thereby achieving more precise control when laser cutting the silicon carbide ingot, and then obtaining high-quality silicon carbide wafers. In addition, multiple sub-beams are used to cut the silicon carbide ingot. Since the multiple sub-beams are spread out along a preset direction parallel to the cutting plane of the silicon carbide ingot, they have a larger coverage area, which improves the cutting efficiency. Therefore, the processing of silicon carbide ingots brings a double improvement in efficiency and quality.

[0125] That is to say, in the laser processing scheme of the present application, the line spacing of the laser scanning of the silicon carbide ingot can be significantly increased, thereby reducing the number of laser scans. This improvement helps to reduce the accumulation of thermal effects of the laser on the silicon carbide ingot, thereby reducing the extension of microcracks caused by thermal stress, and thus improving the overall preparation quality of the silicon carbide ingot. In addition, by adopting spherical aberration correction technology, the spot size of the laser inside the silicon carbide ingot can be greatly reduced, and the spot morphology can be improved. This not only reduces the depth of microcracks generated during the processing, but also reduces processing losses.

[0126] The above is a description from the perspective of the light beam of why the laser processing solution of the present application can bring about a double improvement in efficiency and quality in the processing of silicon carbide ingots. The following will be described from the perspective of the selection of the light source.

[0127] In order to more effectively control the growth area of ​​the microcracks, a specific light source may be selected, for example, a femtosecond laser may be selected as the type of laser 110. The heat-affected zone generated by the femtosecond laser when processing the silicon carbide ingot 190 is small, so microcracks are hardly formed outside the laser action area, thereby enabling precise control of the growth of the microcracks.

[0128] The femtosecond laser includes the following laser parameters: an adjustable repetition frequency of 0 to 2 MHz, an adjustable average power of 0 to 20 W, and an adjustable pulse width of 50 fs to 10 ps. During cutting, the laser beam has a pulse width of 190 fs to 350 fs, a repetition frequency of 50 KHz to 500 KHz, and an average power of 1 W to 2 W. Preferably, the pulse width is 300 fs, the repetition frequency is 100 KHz, and the average power is 1.5 W. At this time, each spherical aberration compensation beam has the same pulse width and repetition frequency as the laser beam, and multiple spherical aberration compensation beams divide the average power of the laser beam equally. For example, the pulse width of each of the seven spherical aberration compensation beams is 300 fs, the repetition frequency is 100 KHz, and the average power is 1.5 / 7=0.2 W.

[0129] Since the pulse width of 190fs to 350fs (for example, 300fs) is less than the time of lattice vibration (1ps to 100ps), the energy deposition of a single pulse ends before the lattice vibration, thereby greatly reducing the generation of thermal effects. In addition, a repetition frequency of 50KHz to 500KHz (for example, 100KHz) combined with a preset cutting speed of 15mm / s to 50mm / s (for example, 25mm / s) can also greatly reduce the thermal effect caused by the accumulation of multiple pulses. The reduction of thermal effects means that the growth of microcracks can be precisely controlled.

[0130] When cutting the silicon carbide ingot 190, the distance between adjacent laser processing lines will also be considered because the femtosecond laser pulses generated by the femtosecond laser will generate a certain heat diffusion area. The distance between adjacent laser processing lines is made larger than the size of the heat diffusion area caused by the femtosecond laser pulse, thereby reducing the superposition effect of the heat diffusion area, and thus being able to accurately control the growth of microcracks. Figure 7 As shown, the interval d between adjacent laser processing lines 210 is 30 μm to 50 μm. Preferably, the interval d between adjacent laser processing lines 210 is 40 μm.

[0131] When the focused spherical aberration compensation beam moves on the silicon carbide ingot 190 at a preset cutting path and a preset cutting speed, the interior of the silicon carbide ingot 190 is modified to form a silicon carbide modified layer (also called a microcrack layer) 191, such as Figure 8 The silicon carbide modified layer 191 is used as the base point for separating the silicon carbide wafer, and combined with the subsequent auxiliary splitting process, the silicon carbide wafer can be smoothly cut from the silicon carbide ingot 190 .

[0132] In addition, when the focused spherical aberration compensation beam moves on the silicon carbide ingot 190, the focused spherical aberration compensation beam can not only modify the cutting path being traveled, but also produce a pre-modification effect on the adjacent cutting path perpendicular to the cutting path being traveled, which makes the growth of microcracks more uniform and controllable, thereby reducing the difficulty of the subsequent splitting process and improving the quality of the silicon carbide wafer.

[0133] Therefore, in the laser processing scheme of the present application, a femtosecond laser with preset laser parameters is used, combined with a preset cutting speed and the spacing between laser processing lines, to cut the silicon carbide ingot, which can also reduce the roughness generated on the surface of the silicon carbide wafer, thereby improving the quality of the silicon carbide wafer.

[0134] In summary, whether using a spherical aberration compensation beam or a femtosecond laser, the purpose is to concentrate the microcracks on the cutting path as much as possible, so that the microcracks will not expand to the surrounding areas due to the heat diffusion of the laser, thereby being able to accurately control the growth of the microcracks.

[0135] In the present application, microcracks inside the silicon carbide ingot are stably generated by controlling the angle of the laser beam (i.e., collimation), power control, and light field regulation, and a subsequent auxiliary splitting process is combined to obtain high-quality silicon carbide wafers.

[0136] Combination of the above Figures 1 to 8 , describes in detail the device embodiment of the present application, and the following is combined with Fig.11 , describe the method embodiments of the present application in detail.

[0137] Fig. 9 1 is a flow chart of a method for cutting a silicon carbide ingot provided in an embodiment of the present application. The cutting method is executed by the controller 109 in the above device embodiment, and the parts not described in detail can be referred to the above device embodiment. The cutting method includes the following contents.

[0138] S910: Determine spherical aberration caused by the mismatch between the refractive index of air and the refractive index of the silicon carbide ingot, and determine a spherical aberration compensation phase diagram required to compensate for the spherical aberration.

[0139] In one example, the controller determines the spherical aberration caused by the mismatch between the refractive index of air and the refractive index of the silicon carbide ingot by the method based on the Zernike polynomial phase difference described above, and then determines the spherical aberration compensation phase diagram required to compensate for the spherical aberration based on the GCS algorithm described above. The detailed determination process has been described above, so it will not be repeated here.

[0140] Of course, the method for determining spherical aberration is not limited to the Zernike polynomial phase difference. In practical applications, those skilled in the art can flexibly select other applicable methods according to specific needs and scenarios.

[0141] It should be understood that through step S910, the spherical aberration generated by each sub-beam after sequentially passing through the air and the silicon carbide ingot can be determined, and the spherical aberration compensation phase diagram corresponding to each sub-beam can be designed accordingly.

[0142] S920: Control the spatial light modulator to load multiple spherical aberration compensation phase maps, and based on the multiple spherical aberration compensation phase maps, perform spherical aberration compensation on multiple sub-beams arranged along a preset direction, and output multiple spherical aberration compensation beams, wherein one spherical aberration compensation phase map is used to perform spherical aberration compensation on one sub-beam.

[0143] In fact, step S910 can be regarded as a process of spherical aberration correction. In this process, the spherical aberration compensation amount required for each sub-beam can be determined through spherical aberration correction, and the spherical aberration compensation phase diagram can be determined. The following step S920 is the implementation stage of spherical aberration compensation. In this stage, spherical aberration compensation is performed on each sub-beam based on the spherical aberration compensation phase diagram determined in step S910 to ensure that the focus of the beam is more accurate. The spherical aberration compensation amount is specifically reflected by the spherical aberration compensation phase diagram.

[0144] S930: Control the multiple focused spherical aberration compensation beams to move on the silicon carbide ingot at a preset cutting path and a preset cutting speed, and modify the interior of the silicon carbide ingot to complete the cutting of the silicon carbide ingot, wherein the multiple focused spherical aberration compensation beams are obtained after focusing the multiple spherical aberration compensation beams.

[0145] The controller controls the scanning mechanism so that the focused spherical aberration compensation beam moves on the silicon carbide ingot at a preset cutting path and a preset cutting speed. During the movement of the focused spherical aberration compensation beam, the interior of the silicon carbide ingot is modified to complete the cutting of the silicon carbide ingot.

[0146] The angle between the preset direction and the first direction perpendicular to the preset cutting path is greater than or equal to 0° and less than or equal to 45°. The spacing between adjacent laser processing lines in the preset cutting path is 30 μm to 50 μm, and the preset cutting speed is 15 mm / s to 50 mm / s.

[0147] In addition, the cutting method further comprises controlling the laser to output a laser beam having preset laser parameters, wherein the laser beam is split by a beam splitting element to obtain a plurality of sub-beams.

[0148] Preset laser parameters include pulse widths from 190fs to 350fs, repetition rates from 50KHz to 500KHz, and average powers from 1W to 2W.

[0149] Therefore, in the laser cutting scheme of the present application, spherical aberration compensation is performed on multiple sub-beams arranged along a preset direction, which can significantly reduce the spot size of each focused sub-beam in the direction of the optical axis inside the silicon carbide ingot, and reduce the length of the growth area of ​​the microcracks generated along the direction of the optical axis during the processing, thereby achieving more precise control when laser cutting the silicon carbide ingot, and then obtaining high-quality silicon carbide wafers. In addition, multiple sub-beams are used to cut the silicon carbide ingot. Since the multiple sub-beams are spread out along a preset direction parallel to the cutting plane of the silicon carbide ingot, they have a larger coverage area, which improves the cutting efficiency. Therefore, the processing of silicon carbide ingots has brought about a double improvement in efficiency and quality.

[0150] Combination of the above Fig. 9 , describes the method embodiment of the present application in detail, and the following is combined with Fig.10 , describes in detail the system embodiment of the present application. It should be understood that the description of the method embodiment corresponds to the description of the system embodiment, so the parts not described in detail can refer to the previous method embodiment.

[0151] Fig.10 1 is a schematic diagram of the structure of a silicon carbide ingot cutting system provided in an embodiment of the present application. The cutting system 1000 may include: a determination module 1010, a first control module 1020 and a second control module 1030. These modules are described in detail below.

[0152] The determination module 1010 is used to determine the spherical aberration generated due to the mismatch between the refractive index of air and the refractive index of the silicon carbide ingot, and determine a spherical aberration compensation phase diagram required to compensate for the spherical aberration.

[0153] The first control module 1020 is used to control the spatial light modulator to load multiple spherical aberration compensation phase maps, and based on the multiple spherical aberration compensation phase maps, perform spherical aberration compensation on multiple sub-beams arranged along a preset direction, and output multiple spherical aberration compensation beams, wherein one spherical aberration compensation phase map is used to perform spherical aberration compensation on one sub-beam.

[0154] The second control module 1030 is used to control the scanning mechanism so that the focused spherical aberration compensation beam moves on the silicon carbide ingot at a preset cutting path and a preset cutting speed. During the movement of the focused spherical aberration compensation beam, the interior of the silicon carbide ingot is modified to complete the cutting of the silicon carbide ingot.

[0155] The cutting system 1000 may further include: a third control module, used to control the laser to output a laser beam with preset laser parameters, wherein the laser beam is split by the beam splitting element to obtain a plurality of sub-beams.

[0156] Fig.11 1 is a block diagram of a laser processing system provided in an embodiment of the present application. The laser processing system 1100 may be, for example, a computing device having computing functions. The laser processing system 1100 may include a memory 1110 and a processor 1120 (which may be understood as the controller 109 described above). The memory 1110 may be used to store executable code. The processor 1120 may be used to execute the executable code stored in the memory 1110 to implement the steps in the various methods described above. In some embodiments, the laser processing system 1100 may further include a network interface 1130, and data exchange between the processor 1120 and an external device may be implemented through the network interface 1130.

[0157] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loading and executing computer program instructions on a computer, the process or function according to the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (Digital Subscriber Line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server, a data center, etc. that contains one or more available media integrations. The available media may be magnetic media (eg, floppy disks, hard disks, magnetic tapes), optical media (eg, digital video discs (DVD)), or semiconductor media (eg, solid state disks (SSD)).

[0158] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments of the present application can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0159] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0160] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0161] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0162] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A laser processing device, characterized in that: include: A laser, used for emitting a laser beam with preset laser parameters; A beam splitting element, used for splitting the laser beam into a plurality of sub-beams arranged along a preset direction; A spherical aberration compensation element, used for performing spherical aberration compensation on the multiple sub-beams and outputting multiple spherical aberration compensated beams; The scanning mechanism is used to focus the multiple spherical aberration compensation beams, and use the multiple focused spherical aberration compensation beams to cut the silicon carbide ingot at a preset cutting path and a preset cutting speed.

2. The laser processing device according to claim 1, characterized in that: Also includes: A controller, configured to determine the spherical aberration caused by the mismatch between the refractive index of air and the refractive index of the silicon carbide ingot, and determine a spherical aberration compensation phase diagram required to correct the spherical aberration, wherein the spherical aberration compensation element comprises a spatial light modulator, the spatial light modulator is loaded with a plurality of the spherical aberration compensation phase diagrams, and one spherical aberration compensation phase diagram is used to perform spherical aberration compensation on one sub-beam; and / or The laser processing device further includes: a controller, configured to control the laser to emit the laser beam having the preset laser parameters, control the spherical aberration compensation element to perform spherical aberration compensation on the multiple sub-beams, and control the scanning mechanism so that the multiple focused spherical aberration compensation beams cut the silicon carbide ingot at the preset cutting path and the preset cutting speed; and / or The laser processing device further includes: a controller, wherein the scanning mechanism includes a focusing optical element and a three-axis translation stage for carrying the silicon carbide ingot, the focusing optical element is used to focus the multiple spherical aberration compensation beams to obtain the multiple focused spherical aberration compensation beams, and the controller controls the three-axis translation stage to move so that the multiple focused spherical aberration compensation beams cut the silicon carbide ingot at the preset cutting path and the preset cutting speed; and / or The laser processing device also includes: a controller, wherein the scanning mechanism includes a focusing optical element and a galvanometer group, the focusing optical element is used to focus the multiple spherical aberration compensation beams to obtain the multiple focused spherical aberration compensation beams, and the controller controls the deflection angle of the galvanometer group so that the multiple focused spherical aberration compensation beams can cut the silicon carbide ingot at the preset cutting path and the preset cutting speed.

3. The laser processing device according to claim 1 or 2, characterized in that: The beam splitting element comprises a Dammann grating.

4. The laser processing device according to claim 1 or 2, characterized in that: An angle between the preset direction and a first direction perpendicular to the preset cutting path is greater than or equal to 0° and less than or equal to 45°.

5. The laser processing device according to claim 1 or 2, characterized in that: The preset cutting speed is 15 mm / s to 50 mm / s, and the spacing between adjacent laser processing lines in the preset cutting path is 30 μm to 50 μm.

6. The laser processing device according to claim 1 or 2, characterized in that: The laser comprises a femtosecond laser, and the preset laser parameters comprise: a pulse width of 190 fs to 350 fs, a repetition frequency of 50 KHz to 500 KHz, and an average power of 1 W to 2 W.

7. A method for cutting a silicon carbide ingot, characterized in that: include: determining spherical aberration generated based on the mismatch between the refractive index of air and the refractive index of the silicon carbide ingot, and determining a spherical aberration compensation phase diagram required to compensate for the spherical aberration; Controlling the spatial light modulator to load a plurality of the spherical aberration compensation phase maps, and based on the plurality of the spherical aberration compensation phase maps, performing spherical aberration compensation on a plurality of sub-beams arranged along a preset direction, and outputting a plurality of spherical aberration compensation beams, wherein one spherical aberration compensation phase map is used to perform spherical aberration compensation on one sub-beam; Controlling a plurality of focused spherical aberration compensation beams to move on the silicon carbide ingot at a preset cutting path and a preset cutting speed, and modifying the interior of the silicon carbide ingot to complete the cutting of the silicon carbide ingot, wherein the plurality of focused spherical aberration compensation beams are obtained after the plurality of spherical aberration compensation beams are focused.

8. The cutting method according to claim 7, characterized in that: The angle between the preset direction and the first direction perpendicular to the preset cutting path is greater than or equal to 0° and or equal to 45°; and / or The spacing between adjacent laser processing lines in the preset cutting path is 30 μm to 50 μm, and the preset cutting speed is 15 mm / s to 50 mm / s.

9. The cutting method according to claim 7 or 8, characterized in that: Also includes: The laser is controlled to output a laser beam having preset laser parameters, wherein the laser beam is split by a beam splitting element to obtain the multiple sub-beams, and the preset laser parameters include a pulse width of 190 fs to 350 fs, a repetition frequency of 50 KHz to 500 KHz, and an average power of 1 W to 2 W.

10. A laser processing system comprising: A memory and a processor, wherein the memory stores executable codes, and the processor is configured to execute the executable codes to implement the method for cutting a silicon carbide ingot according to any one of claims 7 to 9.

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