Method and device for cutting silicon carbide crystal ingot

Abstract

The invention relates to a silicon carbide crystal ingot cutting method and device. According to the method, a modification difficulty area is predicted through production batch information, differentiated laser parameter partition irradiation is adopted, multiple initial modification layers are synchronously formed, and parameters and the target number are dynamically adjusted; and ultrasonic synergistic separation is combined, and continuous surface forming of the modified layer can be ensured through secondary detection and correction. The device comprises at least two laser assemblies, laser irradiation of different positions or parameters can be achieved at the same time, accurate distribution of laser energy is achieved, the influence of uneven materials on laser focusing is eliminated by combining data of modification difficulty of different positions, and balance control over the machining efficiency and precision is achieved in a complete immersion and ultrasonic mode. The problems of low efficiency and poor thickness uniformity caused by repeated grinding needed in traditional laser cutting are solved through laser parameter differential regulation and control, synchronous formation of multiple modified layers, ultrasonic separation and the like, and the machining efficiency and the product quality of silicon carbide crystal ingot cutting are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicon carbide wafer manufacturing, in particular to a cutting method and device of a silicon carbide ingot. BACKGROUND

[0002] As a third-generation semiconductor material, silicon carbide (SiC) is widely used in electric vehicles, photovoltaic energy, radio frequency communication and other fields due to its wide band gap, high thermal conductivity, high breakdown field strength and other excellent characteristics. However, its Mohs hardness is as high as 9.5, and the current mainstream technology in the industry is multi-wire cutting technology, which realizes material separation through the action of steel wire and diamond micro-powder cutting fluid. However, this technology has the following defects: long cutting cycle (6-inch ingot about 100-120 hours, 8-inch up to 200 hours), high material loss rate (only 30 pieces per ingot), and serious environmental pollution (high cost of cutting fluid recycling and processing). Some enterprises try to use diamond wire cutting technology, which shortens the cutting time to 20-60 hours, but has high wire breakage rate and poor product thickness uniformity, which directly affects the subsequent grinding and polishing yield and substrate flatness, and ultimately restricts the performance of the device.

[0003] The existing laser stealth cutting technology focuses on the formation of a modified layer inside the ingot by a specific wavelength laser, and then realizes the separation of the wafer by physical or chemical methods. However, there are still some fundamental limitations: the surface of the peeled ingot is precisely ground by a diamond grinding wheel to obtain a smooth surface, and then the next round of laser irradiation is performed, which is low in efficiency. In addition, the silicon carbide ingot may have regions with different material properties during growth, resulting in different laser absorption rates in different regions. Using the same energy laser cannot guarantee the formation of a continuous micro-crack surface at a certain depth, and there is a cutting difference problem.

[0004] In summary, the cutting method of the silicon carbide ingot needs to be further optimized. SUMMARY

[0005] The purpose of the present application is to accurately control the laser parameters of different regions in the laser cutting of the silicon carbide ingot, eliminate the influence of material differences at different positions on the focused laser, and automatically control the process through the device system to realize the self-controlling of thickness uniformity and processing efficiency.

[0006] In a first aspect, the present application provides a cutting method of a silicon carbide ingot, comprising the following steps: S1, obtaining production batch information of a silicon carbide ingot to be cut; S2, according to the production batch information, obtaining a modified difficulty region of a plurality of historical silicon carbide ingots of the same production batch as the silicon carbide ingot to be cut; S3, merging the modified difficulty regions of all the historical silicon carbide ingots to obtain a current modified difficulty region; S4, irradiating the to-be-cut silicon carbide crystal ingot with the first laser beam to simultaneously form a target number of initial modification layers arranged along a vertical direction in the to-be-cut silicon carbide crystal ingot; wherein the laser parameter corresponding to the current modification difficulty region is a first laser parameter, the laser parameter corresponding to the region other than the current modification difficulty region in the to-be-cut silicon carbide crystal ingot is a second laser parameter, the first laser parameter is different from the second laser parameter, 2 ≤ the target number < n, and n is a total number of modification layers in the to-be-cut silicon carbide crystal ingot; S5, moving the irradiation position of the first laser beam along the vertically upward direction and repeatedly performing S4 until n initial modification layers arranged along the vertical direction are formed in the to-be-cut silicon carbide crystal ingot, to obtain a modified silicon carbide crystal ingot; S6, ultrasonic treating the modified silicon carbide crystal ingot to obtain (n+1) silicon carbide wafers.

[0007] Optionally, S4 specifically comprises: judging whether a current irradiation region in the to-be-cut silicon carbide crystal ingot is the current modification difficulty region; if yes, irradiating the current irradiation region with the first laser beam having the first laser parameter; if no, irradiating the current irradiation region with the first laser beam having the second laser parameter; wherein the laser power in the first laser parameter is greater than the laser power in the second laser parameter; and / or, the laser spot spacing in the first laser parameter is less than the laser spot spacing in the second laser parameter.

[0008] Optionally, step S4 further comprises: judging whether all the initial modification layers meet a first requirement; if yes, performing step S4; if no, continuing to irradiate the initial modification layer that does not meet the first requirement among all the initial modification layers until the first requirement is met.

[0009] Optionally, judging whether the initial modification layer meets the first requirement comprises: photographing the to-be-cut silicon carbide crystal ingot to obtain a current crystal ingot image; judging whether the initial modification layer in the current crystal ingot image is continuous and planar; if yes, determining that the initial modification layer meets the first requirement.

[0010] Optionally, in the process of repeatedly performing S4, the power of the first laser beam gradually decreases or gradually increases; And / or, in the process of repeatedly performing S4, the target number gradually decreases or gradually increases.

[0011] Optionally, before S6, the n initial modification layers are not continuous. The n initial modification layers are scanned layer by layer along the vertical upward direction by using the second laser beam to obtain a modified silicon carbide crystal ingot with n modification layers.

[0012] Optionally, the method further comprises: determining whether the n modification layers meet a second requirement; if not, continuing to irradiate the modification layers that do not meet the second requirement until the modification layers after irradiation meet the second requirement; The second requirement includes that the modification layers are continuous.

[0013] Optionally, S6 specifically comprises: placing the modified silicon carbide crystal ingot in a containing groove with liquid; wherein the bottom of the containing groove is provided with a first ultrasonic device, and the sidewall of the containing groove is provided with a second ultrasonic device, and the power of the first ultrasonic device is greater than that of the second ultrasonic device; The n initial modification layers are scanned layer by layer along the vertical upward direction by using the second laser beam to obtain a modified silicon carbide crystal ingot with n modification layers.

[0014] Optionally, the method for confirming the modification difficulty area comprises: irradiating the historical silicon carbide crystal ingot by using a third laser beam; detecting the irradiated area to obtain area detection information; wherein the irradiated area is the area of the historical silicon carbide crystal ingot irradiated by the third laser beam, the area detection information includes sub-detection information of each position in the irradiated area, and the sub-detection information includes reflectivity or fluorescence signal value; determining whether the sub-detection information falls within a set range; If yes, the irradiated area is confirmed as the modification difficulty area.

[0015] The cutting method of the silicon carbide ingot provided by the application firstly locates the potential modification difficult area of the current ingot by obtaining and analyzing the modification difficult area of the historical silicon carbide ingot, reduces the trial-and-error parameter adjustment of a single ingot by using the cumulative effect of batch processing data, improves the accuracy of the laser parameter preset, and reduces the risk of modification layer formation failure caused by material microscopic differences. The first laser parameter is used for the modification difficult area, and the second laser parameter is used for the non-difficult area, so as to realize the allocation of laser energy, eliminate the influence of material hardness unevenness on laser focusing, and ensure that the modification layer is uniformly formed in the whole ingot range; the modification threshold of the difficult area is broken through, the transverse expansion ability of micro-cracks is enhanced, and the continuity of the modification layer is improved.

[0016] In a second aspect, the application provides a silicon carbide ingot cutting device, which is applied to the cutting method of the silicon carbide ingot described above, and comprises: A laser component, which comprises at least two laser assemblies respectively used for emitting laser beams to the silicon carbide ingot to be cut to obtain a modified silicon carbide ingot; A bearing part, which comprises a base and a moving platform, the base is used for bearing and fixing the modified silicon carbide ingot, and the moving platform is used for driving the base to move relative to the laser component; A containing groove, which contains liquid and is used for containing the modified silicon carbide ingot; wherein the liquid in the containing groove completely immerses the modified silicon carbide ingot; The ultrasonic component is arranged at the bottom and / or the sidewall of the containing groove, and is used for ultrasonic treatment of the modified silicon carbide ingot to obtain (n+1) silicon carbide wafers.

[0017] The silicon carbide ingot cutting device provided by the application can realize laser irradiation at different positions or parameters at the same time through at least two laser assemblies, realize accurate allocation of laser energy, eliminate the influence of material unevenness on laser focusing by combining the data of modification difficulty at different positions, dynamically adjust the laser power or spot spacing, adapt to the material state change in the modification layer formation process, and ensure the consistency of the modification quality of each layer. The number of laser scanning times is reduced, the traditional layer-by-layer processing mode is optimized to batch layer processing, the total processing time is greatly shortened, the target number can be increased or decreased according to the processing progress, and the balance control of processing efficiency and precision is realized.

[0018] Compared with the prior art, the application solves the problems of low efficiency and poor thickness uniformity caused by repeated grinding in traditional laser cutting through technical means such as laser parameter differential regulation, synchronous formation of multiple modification layers, ultrasonic separation and closed-loop control, and improves the processing efficiency, product quality and equipment automation level of silicon carbide ingot cutting. Through production batch information association, real-time detection of modification layers and automatic parameter adjustment, a closed-loop control system of "data-driven-process monitoring-dynamic correction" is constructed, the thickness uniformity is self-controllable, the dynamic optimization can be performed according to the ingot material, the characteristics of different batches of silicon carbide ingots to be cut are adapted, the manual intervention is reduced, and the equipment automation level is improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structural schematic diagram of a silicon carbide ingot cutting device provided by the application; Figure 2 is a flowchart of a cutting method of a silicon carbide ingot provided by the application.

[0020] Marked for explanation: 100, laser component; 110, laser assembly; 200, bearing part; 210, base; 220, moving platform; 300, accommodating groove; 400, ultrasonic component; 600, silicon carbide ingot. DETAILED DESCRIPTION

[0021] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application will be described in detail below with reference to the drawings. It can be understood that the specific embodiments described herein are only used to explain the application, and not to limit the application. In addition, it should be noted that, in order to facilitate description, only the parts related to the application are shown in the drawings, and not all the structures. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0022] The terms "include" and "have" and any variations thereof in the application are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product or device.

[0023] Reference to“an embodiment” herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase“in an embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. It is expressly understood that any of the embodiments described herein can be incorporated into other embodiments.

[0024] To solve the problems of low efficiency, poor thickness uniformity and complicated process in the existing silicon carbide ingot cutting technology, a cutting method and device based on production batch data to control laser parameters are provided. Through differential laser parameter partition irradiation, multi-initial modification layer synchronous formation and ultrasonic assisted separation technology, the cutting efficiency and wafer quality are improved. The technical solutions are described in detail below in conjunction with the drawings.

[0025] Please refer to Figure 1 , Figure 1 is a structural schematic diagram of a silicon carbide ingot cutting device provided by the application, which is used for cutting a silicon carbide ingot 600. The silicon carbide ingot cutting device includes a laser component 100, a bearing part 200, a containing groove 300 and an ultrasonic component 400.

[0026] The laser component 100 includes at least two laser assemblies 110, which are respectively used to emit laser beams to the silicon carbide ingot 600 to be cut, so as to obtain a modified silicon carbide ingot 600.

[0027] Further, the laser component 100 is an execution unit of the differential parameter irradiation of the application, which includes at least two independently controlled laser assemblies 110 (such as fiber lasers or solid-state lasers). The laser assembly 110 can adopt high-power and small-spot-spacing laser parameters, focus on irradiation of difficult modification areas, break the covalent bond of silicon carbide atoms through high energy density, and enhance the transverse expansion ability of micro-cracks through small spot spacing, to ensure that the difficult area modification layer is continuous. The laser assembly 110 can adopt conventional power and conventional spot spacing laser parameters for irradiation of non-difficult areas, balance energy input and thermal stress control, and avoid cracking or surface damage of the ingot caused by global high-power laser.

[0028] The bearing part 200 includes a base 210 and a moving platform 220. The base 210 is used to bear and fix the modified silicon carbide ingot 600, and the moving platform 220 is used to drive the base 210 to move relative to the laser component 100.

[0029] Further, the silicon carbide crystal ingot 600 can be fixed by vacuum adsorption or mechanical clamping to ensure the stability of the crystal ingot position during processing, eliminate the deviation of laser focusing caused by the displacement of the crystal ingot, and improve the positioning accuracy of the modified layer. The moving platform 220 can integrate three-axis linkage (X / Y / Z direction) guide rails and servo motors to realize the position adjustment of the base 210 relative to the laser component 100, support the relative scanning path planning of the laser beam and the crystal ingot, and adapt to the demand for synchronous formation of multiple initial modified layers.

[0030] The accommodation groove 300 contains liquid, and is used to accommodate the modified silicon carbide crystal ingot 600. The liquid in the accommodation groove 300 can completely immerse the modified silicon carbide crystal ingot 600. The ultrasonic component 400 is arranged at the bottom and / or the side wall of the accommodation groove 300, and is used to ultrasonically treat the modified silicon carbide crystal ingot 600 to obtain (n+1) silicon carbide wafers.

[0031] Further, the accommodation groove 300 is made of a corrosion-resistant material, contains normal-temperature water as an ultrasonic wave transmission medium, and completely immerses the modified silicon carbide crystal ingot 600. The ultrasonic wave transmission medium efficiently transmits the vibration energy of the bottom and side wall ultrasonic devices to the modified layer interface, reduces the external force required for fracture, can also absorb the heat generated during laser processing, avoids the accumulation of thermal stress, and preliminarily flushes the surface of the separated wafers to reduce the residue of debris.

[0032] The ultrasonic component 400 includes a bottom array ultrasonic transducer (main ultrasonic wave) and a side wall ring ultrasonic transducer (auxiliary ultrasonic wave). The frequency of the main ultrasonic wave is 28-40 KHz, and the power is 600-1000 W. The amplitude is large, and the vertical strong vibration drives the modified layer and the upper and lower parts of the carbonized silicon crystal ingot to be cut to resonate and expand the longitudinal crack. The frequency of the auxiliary ultrasonic wave cooperates with that of the main ultrasonic wave, and the power can be 20%-30% of that of the main ultrasonic wave, and the amplitude can be 5-10% of that of the main ultrasonic wave. The horizontal weak vibration assists the expansion of the transverse crack to ensure the flatness of the fracture surface and avoid damage to the edge of the wafer.

[0033] Please refer to Figure 2 , Figure 2 is a flowchart of the cutting method of the silicon carbide crystal ingot provided in the present application. The cutting method includes the following steps: S1, obtaining the production batch information of the carbonized silicon crystal ingot to be cut 600.

[0034] S2, according to the production batch information, obtaining the modified difficult areas of a plurality of historical carbonized silicon crystal ingots 600 of the same production batch as the carbonized silicon crystal ingot to be cut 600.

[0035] S3, merging the modified difficult areas of all historical carbonized silicon crystal ingots 600 to obtain the current modified difficult area.

[0036] S4, irradiating the to-be-cut silicon carbide crystal ingot 600 with the first laser beam to simultaneously form a target number of initial modification layers arranged along a vertical direction in the to-be-cut silicon carbide crystal ingot 600.

[0037] The laser parameter corresponding to the current modification difficulty area is a first laser parameter, the laser parameter corresponding to the area other than the current modification difficulty area in the to-be-cut silicon carbide crystal ingot 600 is a second laser parameter, the first laser parameter is different from the second laser parameter, 2≤target number<n, and n is the total number of modification layers in the to-be-cut silicon carbide crystal ingot 600.

[0038] Further, the target number can be 2, 3, 4, 5 or 6, but is not limited thereto, and can be set according to specific application needs.

[0039] S5, moving the irradiation position of the first laser beam along the vertical upward direction and repeatedly performing S4 until n initial modification layers arranged along the vertical direction are formed in the to-be-cut silicon carbide crystal ingot 600, to obtain a modified silicon carbide crystal ingot 600.

[0040] S6, performing ultrasonic treatment on the modified silicon carbide crystal ingot 600 to obtain (n+1) silicon carbide wafers.

[0041] Firstly, the surface mark of the to-be-cut silicon carbide crystal ingot 600 is scanned or the production database is inquired to obtain the production batch information of the to-be-cut silicon carbide crystal ingot 600, which provides a data basis for subsequent modification difficulty area prediction. Next is the modification difficulty area analysis, based on the production batch information, the processing records of multiple historical silicon carbide crystal ingots 600 under the same batch are called, and the modification difficulty area of the current crystal ingot (such as the material hardness abnormal area, the defect concentration area of the to-be-cut silicon carbide crystal ingot) is obtained by data analysis and combination. The cumulative effect of batch processing data is used to improve the accuracy of laser parameter presetting and reduce the risk of modification layer formation failure caused by material microscopic differences.

[0042] For the modified difficult area and non-difficult area, the first laser parameter and the second laser parameter are set respectively. Specific parameters are as follows: the laser wavelength adopts infrared-visible band (such as 1064nm, 1030nm, 532nm), which ensures the efficient absorption of laser energy in silicon carbide material, the pulse width selects picosecond (10-300 picoseconds) or femtosecond (500-800 femtoseconds) laser, the power is in the range of 50-80W, the repetition frequency is in the range of 100-2000KHz, the high power and small spot spacing laser used in the modified difficult area can break through the material hardness threshold, enhance the transverse expansion ability of micro-cracks, and ensure the continuous formation of the modified layer. The continuous formation of the modified layer refers to the formation of a modified layer with uniform thickness on the entire surface, rather than multiple lines formed by continuous scanning of the laser; the non-difficult area adopts conventional power and conventional spot spacing laser to avoid heat stress concentration and reduce the risk of ingot cracking.

[0043] The first laser beam is used to scan the ingot in the vertical direction, and 2≤target number<n initial modified layers are formed synchronously. During the scanning process, the continuity of the modified layer is judged by real-time image detection (such as CCD camera), and the unqualified area is supplemented with irradiation. Multiple modified layers are formed by single scanning, which optimizes the traditional layer-by-layer processing mode to batch layer stacking processing, shortens the total processing time, dynamically adjusts the laser power or spot spacing (such as gradually increasing the power to adapt to the material state change), and balances the efficiency and accuracy.

[0044] In the repeated scanning process, the laser parameters are dynamically adjusted according to the modified layer formation quality, and the target number is controlled. For example, a higher target number (such as n / 2) is used in the initial scanning to quickly layout the modified layer, and the target number is reduced in the later stage to improve the single layer quality, adapt to the material state change in the modified layer formation process, and ensure the consistency of the modified quality of each layer.

[0045] The modified crystal ingot is immersed into the containing groove 300 containing normal temperature water, and the bottom high-power ultrasonic device and the sidewall low-power ultrasonic device are cooperated to promote the modified layer to be broken by ultrasonic vibration, and (n+1) silicon carbide wafers are separated at one time. The main ultrasonic wave drives the longitudinal crack propagation, the auxiliary ultrasonic wave drives the transverse crack propagation, the peeling time is shortened, and the single ingot wafer separation efficiency is improved. Moreover, the non-contact separation is realized by the ultrasonic separation, mechanical damage is avoided, the wafer peeling yield is improved by more than 20%, and the thickness uniformity is improved. The present application can efficiently form a laser modified layer of silicon carbide without moving the to-be-cut silicon carbide crystal ingot, save the processing procedure of diamond grinding the to-be-cut silicon carbide crystal ingot, reduce the cutting cost, realize one-time positioning and multiple laser scanning to form the whole modified layer, improve the efficiency by at least 30 times, and reduce the cutting time cost by more than 30%. Compared with the traditional "cutting-peeling-grinding-repositioning" cycle mode, the method of the present application completes the whole modified layer scanning by single positioning, reduces the cutting time cost, can eliminate the positioning error, improves the modified layer position accuracy, and realizes full-automatic continuous processing. In addition, high-quality silicon carbide wafers can be cut on the to-be-cut silicon carbide crystal ingot according to the quality of the to-be-cut silicon carbide crystal ingot, such as: the silicon carbide wafer is a silicon carbide seed crystal, and the thickness of the silicon carbide seed crystal is generally near 600-700 μm, which is higher than the thickness of the standard substrate wafer (generally 350 μm or 500 μm). The present application can cut silicon carbide wafers with desired thickness, and improve the applicability of the cutting scheme.

[0046] It is worth noting that the scheme provided by the present application is suitable for cutting of conductive silicon carbide crystal ingots, and is also suitable for cutting of semi-insulating or high-purity silicon carbide crystal ingots.

[0047] In an embodiment, the carbon face or the silicon face of the silicon carbide crystal ingot 600 is used as the laser incidence surface, which adapts to the processing requirements of different to-be-cut silicon carbide crystal ingots.

[0048] In an embodiment, the surface of the silicon carbide crystal ingot 600 can be ground before cutting to reduce the roughness, thereby reducing the reflection of the incident laser, effectively utilizing the laser output energy of the laser, and reducing the heat effect generated in the cutting process.

[0049] In an embodiment, S4 specifically includes: S41: judging whether the current to-be-irradiated area in the to-be-cut silicon carbide crystal ingot 600 is a current modified difficult area.

[0050] S42: if the current to-be-irradiated area in the to-be-cut silicon carbide crystal ingot 600 is a current modified difficult area, a first laser beam with a first laser parameter is used to irradiate the current to-be-irradiated area.

[0051] S43: If the current irradiation region in the silicon carbide ingot to be cut 600 is not the current modification difficult region, the first laser beam with the second laser parameter is used to irradiate the current irradiation region.

[0052] The laser power in the first laser parameter is greater than the laser power in the second laser parameter; and / or, the laser spot spacing in the first laser parameter is less than the laser spot spacing in the second laser parameter.

[0053] The high-power laser provides sufficient energy to break the silicon carbide atomic covalent bond, ensuring the formation of the difficult region modification layer; the small spot spacing enhances the transverse expansion ability of the micro-crack, making the modification layer continuous, and the targeted parameter setting avoids the thermal stress concentration caused by the global high-power laser, reducing the possibility of ingot cracking or surface damage. The balance of the conventional power and the spot spacing controls the energy input and the thermal stress, ensuring the rapid formation of the non-difficult region modification layer while avoiding the material performance degradation caused by excessive heating. Combined with the dynamic parameter adjustment (such as gradually increasing the power or gradually reducing the spot spacing) in step S5, the material state change in the modification layer formation process is adapted, ensuring the consistency of the modification quality of each layer. According to the application needs, high-quality silicon carbide wafers (such as silicon carbide seeds) can be selectively cut on the silicon carbide ingot to be cut, and the thickness of the silicon carbide wafer can be freely selected and determined, improving the utilization rate of the silicon carbide ingot to be cut.

[0054] Further, step S4 further comprises: judging whether all the initial modification layers meet the first requirement; if yes, executing step S5; if no, continuing to irradiate the initial modification layer that does not meet the first requirement in all the initial modification layers until the first requirement is met.

[0055] Specifically, judging whether the initial modification layer meets the first requirement comprises: taking a photo of the silicon carbide ingot to be cut 600 to obtain a current ingot image; judging whether the initial modification layer in the current ingot image is continuous; if yes, it is determined that the initial modification layer meets the first requirement. When continuing to irradiate the initial modification layer that does not meet the first requirement, one laser assembly can be used for irradiation.

[0056] During the laser scanning process, the silicon carbide ingot to be cut 600 is photographed by a CCD camera or an infrared sensor to obtain image information of the current modification layer, and whether it is continuous is judged, the modification layer formation quality is monitored in real time, the problem of discontinuous modification layer caused by local hardness difference of the material or deviation of the laser parameter is avoided, the laser parameter (such as power, spot spacing) or scanning path is adjusted in time through the feedback control mechanism, the modification layer quality meets the subsequent stripping requirement, the crack can be uniformly expanded along the modification layer in the subsequent ultrasonic separation process, and local damage or uneven thickness of the wafer during wafer stripping is avoided.

[0057] In other embodiments, determining whether the initial modification layer meets the first requirement comprises: taking a picture of the carbonized silicon ingot to be cut 600 to obtain a current ingot image; determining whether the distance between two adjacent modification lines in the initial modification layer in the current ingot image is less than a set distance; if yes, it is determined that the initial modification layer meets the first requirement.

[0058] In an embodiment, in the process of repeatedly performing S4, the power of the first laser beam gradually decreases or gradually increases; and / or, in the process of repeatedly performing S4, the target number gradually decreases or gradually increases.

[0059] In combination with the power change and target number adjustment, for example, high power + high target number for rapid layout at the beginning, and low power + low target number for fine correction at the later stage, the modification layer skeleton can be efficiently formed, and in the later stage, the heat damage is reduced and the continuity of the modification layer is finely adjusted through low power.

[0060] In an embodiment, if none of the n initial modification layers is continuous, the second laser beam is used to scan the n initial modification layers layer by layer along the direction of vertical upward, to obtain a modified carbonized silicon ingot 600 with n modification layers. It can be understood that if some of the n initial modification layers are continuous, only the initial modification layers that are not continuous are scanned.

[0061] Further, the moving platform loaded with the carbonized silicon ingot to be cut is restored to the original position before the first layer of modification layer is formed by using an automatic software program to control the moving platform, the software automatically adjusts the position of the laser beam focused inside the carbonized silicon, which must be higher than the position of the laser beam focused when the first layer of modification layer is formed, and the height difference of the position is related to the thickness of the cut wafer, and the processing platform loaded with the carbonized silicon ingot to be cut is moved to realize laser irradiation scanning of the whole area of the carbonized silicon ingot to be cut, and further form carbonized silicon amorphous modification layers at other positions.

[0062] Through the layer-by-layer scanning of the second laser beam, the discontinuous areas in the initial modification layer can be repaired, ensuring that each layer is continuous, thereby improving the efficiency of subsequent ultrasonic separation and the quality of the wafer. If the modification layer is discontinuous, it may not be uniformly broken during ultrasonic treatment, resulting in damaged edges or uneven thickness of the wafer. The treatment of the second laser beam can reduce such defects and improve the yield. The second laser beam can use different parameters (such as power and spot spacing) to treat the discontinuous areas, avoiding excessive processing of healthy areas while ensuring that problem areas are adequately treated.

[0063] Further, the above method further comprises: determining whether the n modification layers meet a second requirement; if not, continuing to irradiate the modification layers that do not meet the second requirement in the n modification layers until the modification layers after irradiation meet the second requirement; wherein the second requirement comprises: the modification layer is continuous.

[0064] Continuous surface formation is a key quality indicator of the modified layer, directly affecting the effect of subsequent ultrasonic separation. If the modified layer is not continuous, it may cause the wafer to break or have uneven thickness during peeling. Through secondary detection and correction, it is ensured that all modified layers meet the requirements, avoiding wafer damage or uneven thickness caused by discontinuity; moreover, through the combined use of the first laser beam and the second laser beam, the modified layer can be formed more accurately, reducing the irradiation damage to the to-be-cut silicon carbide ingot and improving the utilization rate of the material.

[0065] In an embodiment, S6 specifically comprises: placing the modified silicon carbide ingot 600 in the containing groove 300 with liquid; wherein the bottom of the containing groove 300 is provided with a first ultrasonic device, and the sidewall of the containing groove 300 is provided with a second ultrasonic device, and the power of the first ultrasonic device is greater than that of the second ultrasonic device; using the first ultrasonic device and the second ultrasonic device to ultrasonically treat the modified silicon carbide ingot 600, so that the initial modified layer is broken, and (n+1) silicon carbide wafers are obtained.

[0066] The silicon carbide ingot 600 containing a plurality of modified layers after laser modification is subjected to liquid ultrasonic wave peeling to realize the mutual complete separation of the silicon carbide wafers and the wafers, and the silicon carbide wafers with the required thickness are obtained. Different thicknesses of silicon carbide wafers can be obtained. The to-be-cut silicon carbide ingot 600 of the conductive type appears a silicon carbide facet growth phenomenon due to the presence of a doping element. The processing performance of silicon carbide at the facet is different from that in the normal region, and a large amount of processing is required. Therefore, the yield of the facet silicon carbide material after multi-wire cutting and polishing is low. The technical solution of the present application can adjust the thickness of the silicon carbide wafer containing the facet region, cut it into a thicker silicon carbide wafer, and after polishing, the silicon carbide product of the standard size can be met, and the material utilization rate of the original silicon carbide ingot is improved.

[0067] In an embodiment, the confirmation method of the difficult modification area comprises: (A1) irradiating the historical silicon carbide ingot 600 with a third laser beam.

[0068] (A2) detecting the irradiated area to obtain area detection information.

[0069] The irradiated area is the area of the historical silicon carbide ingot 600 irradiated by the third laser beam, and the area detection information includes sub-detection information of each position in the irradiated area. The sub-detection information includes reflectivity or fluorescence signal value.

[0070] (A3) judging whether the sub-detection information falls within a set range.

[0071] (A4) if the sub-detection information falls within the set range, the irradiated area is confirmed as a difficult modification area.

[0072] By setting a threshold range of reflectivity or fluorescence signal, it is determined whether the irradiation area is a modification difficult area, and the modification difficult area such as a defect concentrated area or a hardness abnormal area of the silicon carbide ingot to be cut is located, so that the number of parameter adjustment in subsequent processing is reduced, thereby improving the accuracy of laser parameter presetting and reducing the risk of modification layer formation failure caused by material difference.

[0073] Further, the mechanical external force can be applied during the ultrasonic peeling process to realize rapid peeling of the multi-layer wafer, and after polishing and grinding, the 8-inch silicon carbide substrate product with a standard thickness of 350 μm can be obtained. Specific embodiments Some specific embodiments will be further introduced below, and the technical solutions of the present application will be further described in detail.

[0075] First step: grind the carbon face of the silicon carbide ingot (conductive silicon carbide, crystal type 4H, diameter 8 inches, thickness 20 mm) with high-precision diamond grinding wheel to make the surface roughness less than 10 nm.

[0076] Second step: adsorb the silicon carbide ingot on the porous ceramic base.

[0077] The porous ceramic base is fixed on a movable platform that can move quickly, and the position of the laser and the laser output beam is fixed during cutting. By moving the platform in the X and Y directions, the laser can scan and cut the entire area of the silicon carbide ingot to form a modification layer.

[0078] Third step: irradiate the ingot with laser to form 40 initial modification layers. Specifically, the following steps are included: (1) Learn the areas difficult to crack during modification of the silicon carbide ingot with different reflectivity or fluorescence signals from a large number of modification samples (samples formed by modifying historical silicon carbide ingots) in the same batch in advance. Assume that the modification difficult area corresponding to a large number of modification samples (same size, thickness and material) is A, and directly use the A area as the modification difficult area of the ingot to be cut.

[0079] (2) Irradiate the ingot with laser, and form 4 irradiation points in the vertical direction at a time. Adjust the position of the laser component 100 to irradiate the silicon carbide ingot 600 to be cut by the moving platform, and realize the whole surface scanning of the silicon carbide ingot 600 to be cut.

[0080] (3) Then cool the ingot to form a micro-crack structure near each irradiation point.

[0081] When the current pre-irradiation area is a modification difficult area, increase the laser power and reduce the spot spacing when scanning in the modification difficult area.

[0082] (4) The obtained crystal ingot is photographed by using a CCD to obtain a current crystal ingot image; whether 40 initial modification layers in the current crystal ingot image meet the first requirement is judged; if the first requirement is met, the next step is continued; if the first requirement is not met, the initial modification layers that do not meet the first requirement are continuously irradiated until the first requirement is met.

[0083] The first requirement includes that the distance between two adjacent modification lines in the initial modification layer is less than a set distance.

[0084] (5) The distance between the laser component 100 and the silicon carbide crystal ingot to be cut 600 is adjusted by moving the platform, and the above steps are repeatedly executed to form 40 initial modification layers that meet the first requirement.

[0085] The laser forms a whole surface of amorphous modification layer inside the silicon carbide crystal ingot to be cut, so that the silicon carbide crystal ingot to be cut has 40 initial modification layers after irradiation.

[0086] Step 4: A pulse laser with transmittance to the silicon carbide crystal ingot to be cut is used to irradiate the 40 initial modification layers.

[0087] The wavelength is 1064 nm, the pulse frequency is 40 KHz, the pulse width is 15 picoseconds, and the laser power is 50 W. The laser is focused at a distance of 480 μm from the plane of the previous modification layer.

[0088] Step 5: The crystal ingot obtained in step 4 is photographed by using a CCD to obtain a current crystal ingot image; whether the current modification layer in the current crystal ingot image is continuous and planar is judged; if the current modification layer is continuous and planar, step 6 is executed; if the current modification layer is not continuous and planar, the current modification layer is continuously irradiated until the current modification layer is not continuous and planar.

[0089] Step 6: The silicon carbide crystal ingot after laser modification is subjected to ultrasonic peeling to realize the mutual complete separation of the silicon carbide wafers, and 40 silicon carbide wafers with a thickness of 480 μm are obtained.

[0090] Step 7: The silicon carbide wafers obtained in step 6 are ground and polished to obtain silicon carbide wafers with a thickness of 350 μm.

[0091] As described above, the present application proposes a silicon carbide crystal ingot cutting method and device based on production batch data to control laser parameters, which solves the problems of low efficiency, poor thickness uniformity and complicated process in the prior art. The laser component includes at least two independently controlled laser assemblies. The first laser parameter with high power and small spot spacing is used for the difficult modification area, and the second laser parameter with conventional power and conventional spot spacing is used for the non-difficult area, which ensures that the modification layer in the difficult area is continuous and planar, balances energy input and thermal stress control, avoids cracking or surface damage of the crystal ingot, and improves the thickness uniformity of the modification layer.

[0092] In addition, the initial modification layer is simultaneously formed by the multi-initial modification layer synchronous forming and dynamic adjustment technology, and 2≤target number<n initial modification layers are simultaneously formed by single positioning, the continuity of the modification layer is verified by real-time image detection, and the unqualified area is supplemented by irradiation; the laser power or the target number is dynamically adjusted during repeated scanning to adapt to the material state change. The total processing time of the single ingot is shortened, the efficiency is improved, the positioning error is eliminated, the modification layer position accuracy is improved, and the quality consistency of each layer is improved.

[0093] The application further improves the quality consistency of each layer by the ultrasonic auxiliary non-contact separation technology, immerses the modified crystal ingot in a containing groove containing normal temperature water, drives crack propagation at the bottom by a main ultrasonic wave, separates the crystal wafer by an ultrasonic wave at the side wall, cooperates the main and secondary ultrasonic waves, shortens the peeling time, improves the wafer peeling yield, and supports 2-inch to 12-inch crystal ingot specifications.

[0094] In summary, the application realizes the comprehensive improvement of the silicon carbide crystal ingot cutting efficiency, yield and quality by the whole process optimization of "production batch data driving-differentiated laser parameter regulation-multi-modification layer synchronous forming-ultrasonic cooperative separation", supports the carbon face or the silicon face of the to-be-cut silicon carbide crystal ingot as the laser incident surface, adapts to the different orientation requirements of the to-be-cut silicon carbide crystal ingot, improves the material utilization rate, and meets the requirements of high-end applications for wafer quality.

[0095] The applicant declares that the above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the application can be easily thought out by any person skilled in the art, and all fall within the protection scope and disclosure scope of the application.

Claims

1. A method of cutting a silicon carbide ingot, characterized by, The method comprises the following steps: S1, obtaining production batch information of a to-be-cut silicon carbide crystal ingot; S2, obtaining, according to the production batch information, a plurality of historical silicon carbide crystal ingots of a same production batch as the to-be-cut silicon carbide crystal ingot, and a modification difficult region of each historical silicon carbide crystal ingot; S3, merging the modification difficult regions of all the historical silicon carbide crystal ingots to obtain a current modification difficult region; S4, irradiating the to-be-cut silicon carbide crystal ingot with a first laser beam to simultaneously form a target number of initial modification layers arranged along a vertical direction in the to-be-cut silicon carbide crystal ingot; wherein a laser parameter corresponding to the current modification difficult region is a first laser parameter, a laser parameter corresponding to a region other than the current modification difficult region in the to-be-cut silicon carbide crystal ingot is a second laser parameter, the first laser parameter is different from the second laser parameter, 2≤target number<n, and n is a total number of modification layers in the to-be-cut silicon carbide crystal ingot; S5, controlling the irradiation position of the first laser beam to move along a vertically upward direction and repeatedly performing S4 until n initial modification layers arranged along a vertical direction are formed in the to-be-cut silicon carbide crystal ingot to obtain a modified silicon carbide crystal ingot; S6, performing ultrasonic treatment on the modified silicon carbide crystal ingot to obtain (n+1) silicon carbide wafers.

2. The silicon carbide ingot slicing method according to claim 1, wherein S4 specifically comprises: determining whether a current irradiation region in the to-be-cut silicon carbide crystal ingot is the current modification difficult region; if yes, irradiating the current irradiation region with a first laser beam having the first laser parameter; if no, irradiating the current irradiation region with a first laser beam having the second laser parameter; wherein the laser power in the first laser parameter is greater than the laser power in the second laser parameter; and / or, the laser spot spacing in the first laser parameter is less than the laser spot spacing in the second laser parameter.

3. The silicon carbide ingot slicing method according to claim 1, wherein Step S4 further comprises: determining whether all the initial modification layers meet a first requirement; if yes, performing step S4; if no, continuing to perform laser irradiation on the initial modification layers that do not meet the first requirement until the first requirement is met.

4. The silicon carbide ingot slicing method according to claim 3, wherein Determining whether the initial modification layer meets the first requirement comprises: photographing the to-be-cut silicon carbide crystal ingot to obtain a current crystal ingot image; determining whether the initial modification layer in the current crystal ingot image is continuous and planar; if yes, it is determined that the initial modification layer meets the first requirement.

5. The method according to claim 3, wherein during the repeated execution of S4, the power of the first laser beam gradually decreases or gradually increases; and / or, during the repeated execution of S4, the target number gradually decreases or gradually increases.

6. The silicon carbide ingot slicing method according to claim 1, wherein Since none of the n initial modification layers is continuous and planar, before step S6, the method comprises: scanning the n initial modification layers layer by layer along a vertically upward direction with a second laser beam to obtain a modified silicon carbide crystal ingot having n modification layers.

7. The silicon carbide ingot slicing method according to claim 6, wherein The method further comprises: determining whether the n modified layers meet a second requirement; if not, continuing to irradiate the modified layers that do not meet the second requirement until the modified layers after irradiation meet the second requirement; The second requirement comprises that the modified layers are continuous.

8. The silicon carbide ingot slicing method according to claim 1, wherein S6 specifically comprises: placing the modified silicon carbide ingot in a containing groove with liquid; wherein the bottom of the containing groove is provided with a first ultrasonic device, and the sidewall of the containing groove is provided with a second ultrasonic device, and the power of the first ultrasonic device is greater than that of the second ultrasonic device; using the first ultrasonic device and the second ultrasonic device to perform ultrasonic treatment on the modified silicon carbide ingot, so that the initial modified layer is fractured to obtain the (n+1) silicon carbide wafers.

9. The silicon carbide ingot slicing method according to claim 1, wherein The confirmation method of the difficult modification area comprises: irradiating the historical silicon carbide ingot with a third laser beam; detecting the irradiated area to obtain area detection information; wherein the irradiated area is the area of the historical silicon carbide ingot irradiated by the third laser beam, the area detection information comprises sub-detection information of each position in the irradiated area, and the sub-detection information comprises reflectivity or fluorescence signal value; determining whether the sub-detection information falls within a set range; if yes, confirming that the irradiated area is the difficult modification area.

10. A silicon carbide ingot cutting apparatus for use in a method of cutting a silicon carbide ingot as claimed in any one of claims 1 to 9, characterised in that, comprises: a laser component, comprising at least two laser assemblies respectively used to emit laser beams to a silicon carbide ingot to be cut to obtain a modified silicon carbide ingot; a bearing part, comprising a base and a moving platform, the base is used to bear and fix the modified silicon carbide ingot, and the moving platform is used to drive the base to move relative to the laser component; a containing groove containing liquid, used to contain the modified silicon carbide ingot; wherein the liquid in the containing groove completely immerses the modified silicon carbide ingot; the ultrasonic component is arranged at the bottom and / or sidewall of the containing groove, and is used to perform ultrasonic treatment on the modified silicon carbide ingot to obtain (n+1) silicon carbide wafers.

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