System for laser processing a crystal and method thereof

Abstract

The application provides a laser processing crystal system and a method thereof. The laser processing system comprises a loading module for loading a crystal and moving the crystal, a conveying module for moving the crystal between a cutting station and a slicing station through the loading module, a laser generating module for emitting a slicing laser beam, an optical path adjusting module for irradiating the slicing laser beam on the crystal at the cutting station and scanning the crystal to form a modified layer in the crystal, a wafer separating module for separating a wafer from the crystal through the modified layer, and a control module for controlling the optical path adjusting module and the loading module to move coordinately when the optical path adjusting module controls the slicing laser beam to scan the crystal, so that the slicing laser beam scans the crystal at a constant speed. The loading module, the conveying module, the laser generating module, the optical path adjusting module and the wafer separating module are electrically connected to the control module. The application can improve the quality of the crystal slicing.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, and more particularly to a system and method for laser processing crystals. Background Technology

[0002] Before being used as a substrate, crystals need to undergo multiple processes such as trimming and grinding, slicing, mechanical grinding, chemical mechanical polishing, cleaning, and testing.

[0003] Currently, the crystal slicing process is mostly concentrated on traditional wire / saw cutting. After slicing, the wafer surface has a large number of defects such as cutting marks, chipping, and surface or subsurface structural damage, which directly affects the processing efficiency of subsequent processes. Moreover, the material loss, which is similar to the diameter of the cutting wire, accounts for 30% to 50% of the total crystal volume, thus making it impossible for existing slicing methods to meet the requirements of large-format, ultra-thin, and ultra-flat applications.

[0004] Laser ablation technology is a laser processing technology that can process crystals. It combines laser stealth scribing technology with crystal segmentation technology. It uses a high-energy laser beam that can be focused inside the crystal to form a modified layer at a predetermined position inside the crystal. The modified layer then undergoes crack propagation under external force to achieve the layer-by-layer segmentation of the crystal.

[0005] However, due to the inherent growth characteristics of some crystals, such as SiC crystals, after laser slicing, numerous micron-sized craters, fish-scale or hump-like formations, and concave valleys may appear on their surface, resulting in a surface roughness exceeding 3 μm. The main reason for these defects is the uneven speed of the laser beam scanning the crystal during laser processing, leading to the aforementioned defects.

[0006] Therefore, improving the quality of crystal slicing has become an urgent problem to be solved. Summary of the Invention

[0007] To address the aforementioned problems, the present invention provides a system and method for laser processing crystals. By controlling the coordinated movement of the optical path adjustment module and the loading module, the system ensures that the slicing laser beam scans the crystal at a uniform speed, thereby reducing processing defects on the wafer after slicing and improving the slicing quality of the crystal.

[0008] In a first aspect, the present invention provides a laser processing system, comprising:

[0009] The loading module is used to load the crystal and move it.

[0010] The conveying module is used to move the crystal between the cutting station and the slitting station via the loading module;

[0011] Laser generating module, used to emit segmented laser beams;

[0012] The optical path adjustment module is used to irradiate the crystal at the cutting station with the slicing laser beam and scan the crystal to form a modified layer inside the crystal.

[0013] A wafer separation module is used to separate wafers from crystals through a modified layer;

[0014] The control module is used to control the optical path adjustment module and the loading module to move in coordination when the optical path adjustment module controls the slicing laser beam to scan the crystal, so that the slicing laser beam scans the crystal at a uniform speed.

[0015] The loading module, transmission module, laser generation module, optical path adjustment module, and wafer separation module are all electrically connected to the control module.

[0016] Optionally, the laser processing system may also include: an imaging module;

[0017] The imaging module and the control module are electrically connected;

[0018] An imaging module is used to monitor the burst points and / or cracks of the generated modified layer during the process of scanning the crystal with a segmented laser beam, so as to obtain monitoring results;

[0019] The control module is used to determine, based on the monitoring results, whether the processing parameters of the segmented laser beam need to be adjusted so that the modified layer meets the preset requirements.

[0020] Optionally, the laser generating module is also used to emit a polishing laser beam;

[0021] The transfer module is also used to move the crystal or wafer to the polishing station via the loading module;

[0022] The optical path adjustment module includes: a scanning objective lens unit and a scanning galvanometer unit;

[0023] The scanning objective unit and the scanning galvanometer unit are electrically connected to the control module, respectively.

[0024] The scanning objective unit is used to irradiate the crystal at the cutting station with the slicing laser beam and scan the crystal to form a modified layer inside the crystal.

[0025] The scanning galvanometer unit is used to irradiate the polishing laser beam onto the crystal or wafer at the polishing station and scan the crystal or wafer to polish the surface of the crystal or wafer.

[0026] The control module is used to control the coordinated movement of the scanning objective unit and the loading module when the scanning objective unit controls the slicing laser beam to scan the crystal, and to control the coordinated movement of the scanning galvanometer unit and the loading module when the scanning galvanometer unit controls the polishing laser beam to scan the crystal or wafer, so that the polishing laser beam scans the surface of the crystal or wafer at a uniform speed.

[0027] Optionally, the optical path adjustment module further includes: an optical path switching unit;

[0028] The optical path switching unit is electrically connected to the control module;

[0029] The control module is used to control the optical path switching unit to direct the segmented laser beam to the scanning objective lens unit when the laser transmitting module emits the segmented laser beam, and to control the optical path switching unit to direct the polishing laser beam to the scanning galvanometer unit when the laser transmitting module emits the polishing laser beam.

[0030] Optionally, the polishing laser beam is a Gaussian beam;

[0031] The optical path adjustment module also includes: a beam shaping unit;

[0032] The beam shaping unit is electrically connected to the control module;

[0033] A beam shaping unit is used to transform the phase of a Gaussian beam into a flat-topped laser beam.

[0034] Optionally, the optical path adjustment module may also include: a beam expander unit;

[0035] The beam expander unit is fixedly positioned on the propagation paths of the slicing laser beam and the polishing laser beam;

[0036] The beam expander unit is used to increase the diameter of the slicing laser beam and the polishing laser beam.

[0037] Optionally, the laser processing system may also include: a topography and dimensional measurement module;

[0038] The morphology and dimensional measurement module is electrically connected to the control module;

[0039] The morphology and size measurement module is used to measure the morphology and size of the crystal or wafer surface to obtain measurement results;

[0040] The control module is used to determine whether a crystal or wafer is qualified based on the measurement results.

[0041] In a second aspect, the present invention provides a method for laser processing crystals, comprising a control module applied to a laser processing system as described in any of the above claims, including:

[0042] The control conveying module drives the loading module to move the crystal on the loading module to the cutting station;

[0043] The laser generation module is controlled to emit a segmented laser beam, and the optical path adjustment module and the loading module are controlled to move in coordination so that the segmented laser beam scans the crystal at a uniform speed relative to the wafer through the optical path adjustment module, so as to form a modified layer in the crystal.

[0044] The control and transfer module drives the loading module to move the crystal on the loading module to the slicing station;

[0045] The control wafer separation module applies external force to the crystal to separate the wafer from the crystal through the modified layer.

[0046] Optionally, the steps of controlling the laser generating module to emit segmented laser beams and controlling the optical path adjustment module to coordinate with the loading module 5 further include:

[0047] During the process of scanning the crystal with a segmented laser beam, the imaging module is controlled to monitor the burst points and / or cracks of the generated modified layer in order to obtain monitoring results;

[0048] Based on the monitoring results, determine whether it is necessary to adjust the processing parameters of the segmented laser beam to ensure that the modified layer meets the preset requirements.

[0049] Optionally, prior to the step of controlling the conveying module to drive the loading module to move the crystal on the loading module to the cutting station, the method for laser processing the crystal further includes:

[0050] The control transfer module drives the loading module to move the crystal on the loading module to the polishing station;

[0051] The laser generation module is controlled to emit a polishing laser beam, and the optical path adjustment module and the loading module are controlled to move in coordination so that the polishing laser beam polishes the surface of the crystal at a uniform speed through the optical path adjustment module; 5. The morphology and size of the crystal surface are measured by the morphology and size measurement module to obtain the first measurement result;

[0052] Determine whether the crystal is qualified based on the first measurement result;

[0053] If the result is unsatisfactory, the control laser generation module emits a polishing laser beam to continue polishing the surface of the crystal;

[0054] If successful, proceed with the step of moving the crystal on the loading module to the cutting station;

[0055] After the step of controlling the wafer separation module to apply external force to the crystal to separate wafer 0 from the crystal through the modified layer, the processing method further includes:

[0056] The morphology and dimensions of the wafer surface are measured by a morphology and size measurement module to obtain a second measurement result, and the polishing process parameters are determined based on the second measurement result.

[0057] The control transfer module drives the loading module to move the wafer on the loading module to the polishing station;

[0058] The laser generation module emits a polishing laser beam, and the optical path adjustment module 5 moves in coordination with the loading module according to the polishing process parameters, so that the polishing laser beam selectively passes through the optical path adjustment module to polish the surface of the wafer at a uniform speed.

[0059] The morphology and dimensions of the wafer surface are measured using a morphology and dimension measurement module to obtain a third measurement result;

[0060] The quality of the wafer is determined based on the third measurement result.

[0061] If the wafer fails to meet the requirements, the laser generator module will emit a polishing laser beam to continue polishing the surface of the wafer until it is determined to be qualified.

[0062] The laser crystal processing system and method provided in this invention connects a wafer separation module and an optical path adjustment module to a control module. This allows the control module to simultaneously control the wafer separation module and manage the adjustment module's operating states, thereby controlling the coordinated movement of the optical path adjustment module and the loading module. This ensures that the laser beam scans the crystal at a uniform speed, reducing processing defects such as micron-level craters, fish-scale or hump-like formations, and concave valleys on the wafer surface, thus improving the crystal slab quality. Furthermore, the control module enables integrated control of the crystal slab processing, reducing labor costs and increasing processing efficiency. Attached Figure Description

[0063] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0064] Figure 1 This is a schematic structural diagram of a laser processing system according to an embodiment of the present application, showing the cutting of a crystal located at a cutting station.

[0065] Figure 2 This is a schematic structural diagram of a laser processing system according to an embodiment of the present application, showing the process of slicing a crystal at a slicing station.

[0066] Figure 3 This is a schematic structural diagram of a laser processing system according to an embodiment of the present application, used to polish a crystal located at a polishing station.

[0067] Figure 5This is a schematic structural diagram of a laser processing system according to an embodiment of the present application, used to polish a wafer located at a polishing station.

[0068] Figure 4 This is an example of the optical morphology and three-dimensional confocal image of a wafer separated by a slicing module according to an embodiment of this application. The image on the left is the optical morphology image, and the image on the right is the three-dimensional confocal image.

[0069] Figure 6 This is an optical morphology and three-dimensional confocal image of a polished wafer according to an embodiment of this application. The left side of the image is the optical morphology image, and the right side of the image is the three-dimensional confocal image.

[0070] Figure 7 This is a schematic flowchart illustrating a crystal processing method according to an embodiment of this application.

[0071] Figure Labels

[0072] 1. Loading module; 2. Conveying module; 3. Laser generating module; 4. Optical path adjustment module; 41. Scanning objective lens unit; 42. Scanning galvanometer unit; 43. Optical path switching unit; 431. First reflecting mirror; 432. Second reflecting mirror; 433. Third reflecting mirror; 44. Beam shaping unit; 45. Beam expander unit; 5. Wafer separation module; 6. Control module; 7. Imaging module; 8. Shape and size measurement module; 9. Robotic arm; 10. Crystal; 11. Wafer. Detailed Implementation

[0073] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0074] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0075] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as “below,” “under,” or “below” will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0076] It should be noted that when an element is referred to as "fixedly connected" to another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intervening element. Conversely, when an element is referred to as being "directly on" another element, there is no intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0077] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0078] Firstly, this embodiment provides a system for laser-processing crystals, see [link to previous document]. Figure 1 and Figure 2 The system for laser-processing crystals includes:

[0079] The loading module 1 is used to load the crystal 10 and drive the crystal 10 to translate relative to a plane in three-dimensional space and rotate within the plane;

[0080] The conveying module 2 is used to move the crystal 10 between the cutting station and the slicing station via the loading module 1;

[0081] Laser generating module 3 is used to emit segmented laser beams;

[0082] The optical path adjustment module 4 is used to irradiate the crystal 10 at the cutting station with the slicing laser beam and scan the crystal 10 to form a modified layer in the crystal 10.

[0083] The wafer 11 separation module 5 is used to separate the wafer 11 from the crystal 10 through the modified layer;

[0084] The control module 6 is used to control the optical path adjustment module 4 and the loading module 1 to move in coordination when the optical path adjustment module 4 controls the slicing laser beam to scan the crystal 10, so that the slicing laser beam scans the crystal 10 at a uniform speed.

[0085] Loading module 1, transmission module 2, laser generation module 3, optical path adjustment module 4, and wafer 11 separation module 5 are all electrically connected to control module 6.

[0086] The laser crystal processing system connects the wafer 11 separation module 5 and the optical path adjustment module 4 to the control module 6, allowing the control module 6 to simultaneously control the working status of the wafer 11 separation module 5 and the management adjustment module. This enables the optical path adjustment module 4 to coordinate with the loading module 1, ensuring that the slicing laser beam scans the crystal 10 at a uniform speed. This reduces processing defects on the surface of the wafer 11, such as micron-sized craters, fish-scale or hump-like structures, and concave valleys, thus improving the slicing quality of the crystal 10. Furthermore, the control module 6 achieves integrated control during the crystal 10 slicing process, reducing labor costs and increasing slicing efficiency.

[0087] It should be noted that the coordinated motion enables the optical path adjustment module 4 and the loading module 1 to meet the tracking performance of frequency and speed change trajectories. This allows the polishing laser beam to uniformly change speed on any predetermined processing trajectory while ensuring the uniformity of the processed pattern. The wafer 11 slicing module is a full-contact pneumatic chuck, and this embodiment provides specific limitations on the specific structure of the wafer 11 slicing module; the control module 6 is an industrial control computer.

[0088] Furthermore, the laser-processed crystal system also includes: imaging module 7.

[0089] Imaging module 7 is electrically connected to control module 6. Imaging module 7 is used to monitor the burst points and / or cracks in the generated modified layer during the scanning of crystal 10 by the slicing laser beam, in order to obtain monitoring results. Control module 6 is used to determine, based on the monitoring results, whether it is necessary to adjust the processing parameters of the slicing laser beam to ensure that the modified layer meets preset requirements. By setting imaging module 7, the formation process of the modified layer can be monitored in real time, thereby ensuring that the modified layer meets the process requirements. In this embodiment, the monitoring results include data on the burst points and cracks in the modified layer.

[0090] Furthermore, in combination Figure 3 and Figure 4The laser generating module 3 is also used to emit a polishing laser beam. Under the control of the control module 6, the conveying module 2 is also used to move the crystal 10 or wafer 11 to the polishing station via the loading module 1.

[0091] The optical path adjustment module 4 includes a scanning objective lens unit 41 and a scanning galvanometer unit 42. Both the scanning objective lens unit 41 and the scanning galvanometer unit 42 are electrically connected to the control module 6. Under the control of the control module 6, the scanning objective lens unit 41 irradiates the crystal 10 at the cutting station with a slicing laser beam and scans the crystal 10 to form a modified layer within the crystal 10. Under the control of the control module 6, the scanning galvanometer unit 42 irradiates the crystal 10 or wafer 11 at the polishing station with a polishing laser beam and scans the crystal 10 or wafer 11 to polish the surface of the crystal 10 or wafer 11. The control module 6 controls the scanning objective lens unit 41 to coordinate with the loading module 1 when the scanning objective lens unit 41 controls the slicing laser beam to scan the crystal 10, and controls the scanning galvanometer unit 42 to coordinate with the loading module 1 when the scanning galvanometer unit 42 controls the polishing laser beam to scan the crystal 10 or wafer 11, so that the polishing laser beam scans the surface of the crystal 10 or wafer 11 at a uniform speed.

[0092] By setting up the scanning objective lens unit 41 and the scanning galvanometer unit 42, the laser crystal processing system can not only achieve automated high-quality slicing, but also achieve automated and high-quality polishing of the crystal 10.

[0093] It should be noted that both the slicing laser beam and the polishing laser beam are Gaussian beams. The laser generating module 3 can emit the slicing laser beam and the polishing laser beam at different positions through two different first laser generating sub-modules and second laser generating sub-modules, so that the slicing laser beam directly irradiates the entrance port of the scanning objective lens unit 41, and the polishing laser beam directly irradiates the entrance port of the scanning galvanometer unit 42. In addition, the laser generating module 3 can also emit the slicing laser beam or the polishing laser beam at one position under the control of the control module 6 according to the process requirements to process the crystal 10 or wafer 11 at the corresponding workstation.

[0094] Furthermore, the optical path adjustment module 4 also includes: an optical path switching unit 43, a beam shaping unit 44, and a beam expander unit 45. Both the optical path switching unit 43 and the beam shaping unit 44 are electrically connected to the control module 6.

[0095] The control module 6 is used to control the optical path switching unit 43 to direct the segmented laser beam to the scanning objective lens unit 41 when the laser transmitting module emits the segmented laser beam, and to control the optical path switching unit 43 to direct the polishing laser beam to the scanning galvanometer unit 42 when the laser transmitting module emits the polishing laser beam.

[0096] The beam shaping unit 44 is used to transform the phase of the Gaussian beam into a flat-topped laser beam. The beam expander unit 45 is used to increase the diameter of the segmented laser beam and the polishing laser beam. The beam expander unit 45 is fixedly disposed on the propagation path of the segmented laser beam and the polishing laser beam; the beam shaping unit 44 is fixedly disposed on the propagation path of the polishing laser beam.

[0097] In this embodiment, the polishing station, slitting station, and cutting station are on a straight line on the same horizontal plane. For example, the polishing station and cutting station are located on the left and right sides of the slitting station, respectively. The conveying module 2 is a conveyor belt mechanism, but it is not limited to this; this embodiment does not further limit the conveyor belt mechanism. The loading module 1 is fixedly mounted on the conveyor belt, and the laser generating module 3, optical path adjustment module 4, wafer 11 separation module 5, and imaging module 7 are all located above the conveyor belt. The scanning objective lens unit 41 and the scanning galvanometer unit 42 are located on the left and right sides of the wafer 11 separation module 5, respectively.

[0098] The optical path switching unit 43 includes a driver, a first reflector 431, a second reflector 432, and a third reflector 433. The first and second reflectors 431 and 432 are both located directly above the scanning objective lens unit 41, and the third reflector 433 is directly above the scanning galvanometer unit 42. The first reflector 431 is located directly above the second reflector 432. The beam expander unit 45 and the laser generator module 3 are both located to the left of the first reflector 431, and the laser transmitting module is to the left of the beam expander unit 45. The beam shaping unit 44 is located between the second and third reflectors 432. The second reflector 432 is fixedly connected to the driver, and the driver is electrically connected to the control module 6. The driving component is used to move the second reflector 432 between the reflection station and the avoidance station. When the laser generating module 3 emits a segmented laser beam, the driving component moves the second reflector 432 to the avoidance station so that the segmented laser beam is directly taken into the entrance port of the scanning objective lens unit 41 after being reflected by the first reflector 431. When the laser generating module 3 emits a polishing laser beam, the driving component moves the second reflector 432 to the reflection station so that the polishing laser beam is irradiated by the second reflector 432 after being reflected by the first reflector 431. The second reflector 432 then reflects the polishing laser beam to the third reflector 433, and the third reflector 433 takes the polishing laser beam into the entrance port of the scanning galvanometer unit 42.

[0099] The driving component can be a motor drive assembly, but this embodiment does not specify a particular one.

[0100] Furthermore, the laser-processed crystal system also includes a morphology and size measurement module 8. The morphology and size measurement module 8 is electrically connected to the control module 6. The morphology and size measurement module 8 is used to measure the morphology and size of the surface of the crystal 10 or wafer 11 to obtain measurement results. The control module 6 is used to determine whether the crystal 10 or wafer 11 is qualified based on the measurement results, or to set the polishing position of the polishing laser beam based on the measurement results, depending on the specific process.

[0101] It should be noted that, in this embodiment, the laser-processed crystal system further includes a robotic arm 9. The robotic arm 9 is used to load and unload the crystal 10 or wafer 11 onto the loading module 1.

[0102] Secondly, this embodiment provides a system for laser-processing SiC crystals 10. The laser-processing crystal system in this embodiment has the same structure as the laser-processing crystal system provided in the first aspect. See also Figures 1 to 4 This laser crystal processing system primarily replaces the two traditional methods of wire / saw cutting and mechanical grinding for processing SiC crystals 10. Its working process is as follows:

[0103] First, the robotic arm 9 places the SiC crystal 10 onto the loading module 1, which then secures the bottom of the SiC crystal 10 by adsorption. Next, the conveying module 2 transports the loading module 1 directly below the scanning galvanometer unit 42, i.e., to the polishing station. Simultaneously, the optical path adjustment module 4 adjusts the optical path so that the polishing laser beam emitted by the laser generating module 3 irradiates the upper and side surfaces of the SiC crystal 10 via the beam shaping unit 44 and the scanning galvanometer unit 42, thereby removing crystallization residue from the upper and side surfaces of the SiC crystal 10.

[0104] Preferably, the polishing process uses an ultraviolet femtosecond laser with a power of 1-30W and a wavelength of 320nm, 336nm, 343nm, 355nm, 358nm, or 369nm, or an infrared femtosecond laser with a power of 5-15W and a wavelength of 1030nm, 1046nm, 1056nm, 1060nm, 1064nm, or 1070nm. The light spot diameter irradiating the outer surface of the SiC crystal 10 is a square or circular flat-top beam with a pulse width of 20fs-320fs. Simultaneously, the process involves 1-30 scans at a speed of 0.5mm / s-3.5m / s, with a time interval of 1s-30s between each scan. Furthermore, the loading module 1 can achieve translation around the X and Y axes and rotation around the Z axis. Simultaneously, the scanning galvanometer unit 42 and the loading module 1 can move collaboratively under the control of the control module 6. This collaborative movement enables the scanning galvanometer unit 42 and the loading module 1 to meet the tracking performance of frequency and speed-changing trajectories. This allows the polishing laser beam to uniformly change speed along any predetermined processing trajectory while ensuring the uniformity of the processed pattern. Since the SiC crystal 10 targeted in this invention can be at least 6 inches in size, the scanning area of ​​the scanning galvanometer unit 42 cannot cover SiC crystals 10 of this size. Therefore, continuous splicing scanning laser polishing of specific areas is necessary. However, splicing inevitably causes splicing stripes, affecting subsequent laser slicing effects and processing efficiency. This embodiment, by controlling the coordinated movement of the optical path adjustment module 4 and the loading module 1, effectively avoids the occurrence of splicing stripes caused by splicing scanning laser polishing.

[0105] Furthermore, this invention employs a morphology and dimensional measurement module 8 to measure the laser-polished SiC crystal 10. The morphology and dimensional measurement module 8 has a morphology measurement accuracy higher than 0.02 μm and a dimensional measurement accuracy higher than 0.05 μm. The measured variables include surface morphology, surface roughness, flatness, and warpage. If the polished surface of the wafer 11 is found to be unqualified by the morphology and dimensional measurement module 8, the laser polishing process is repeated. If it is qualified, the next step of laser slicing is performed. This ensures that the surface finish of the upper and side surfaces of the SiC crystal 10 meets the irradiation requirements for internal focusing of the slicing laser beam, and that the focal point of the slicing laser beam is 100% focused on the same reference plane inside the SiC crystal 10 along any predetermined processing trajectory, facilitating the formation of a high-quality modified layer.

[0106] Furthermore, the moving loading module 1 places the laser-polished SiC crystal 10, which meets the requirements, directly below the scanning objective unit 41, i.e., the slicing station. Simultaneously, the optical path adjustment module 4 adjusts the optical path, and the laser beam emitted by the laser generating module 3 under the control of the control module 6 is focused by the scanning objective unit 41 onto a preset position on the same reference plane inside the SiC crystal 10. This preset position can be any vertical or horizontal position inside the SiC crystal 10. Subsequent continuous irradiation by the slicing laser beam forms a modified layer.

[0107] It should be noted that the segmented laser beam is a nanosecond green Gaussian laser beam with a wavelength of 3-10W, ranging from 512nm, 517nm, 522nm, 532nm, 541nm, or 553nm. Simultaneously, the operating pulse width of the segmented laser beam is 38ns, 157ns, 180ns, 200ns, 238ns, or 366ns, the operating frequency is 6kHz, 8kHz, 10kHz, 66kHz, 479kHz, or 785kHz, and the scanning speed is 37mm / s, 200mm / s, 389mm / s, 470mm / s, 793mm / s, 1578mm / s, or 2753mm / s. Furthermore, the scanning spacing between each focused line of the segmented laser beam on the same reference plane is 2μm, 6μm, 12μm, 26μm, 38μm, 45μm, or 59μm. In addition, during the scanning of a preset position by the segmented laser beam, the visual imaging module 7 needs to observe the burst point and crack propagation direction of the modified layer. If the burst point and crack propagation direction are not found to be propagating in the preset direction, the same position needs to be scanned a second, third, fourth and fifth time. Once the observation effect is good enough to ensure that the SiC wafer 11 of the required size and thickness can be accurately segmented from the SiC crystal 10, the emission of the segmented laser beam can be terminated.

[0108] Since the SiC crystal 10 targeted in this invention can be no smaller than 6 inches, and the scanning objective unit 41 and the loading module 1 exhibit two states during the aforementioned processing speed—acceleration at the start and deceleration at a sudden stop—uneven processing of the slab laser beam can occur in these two states. However, the laser crystal processing system provided in this embodiment, under the control of the control module 6, can achieve coordinated movement between the loading module 1 and the scanning objective unit 41. This coordinated movement enables the loading module 1 and the scanning objective unit 41 to meet the tracking performance of frequency and speed variation trajectories. This allows the slab laser beam to uniformly vary its speed along any predetermined processing trajectory while ensuring the uniformity of the processed pattern.

[0109] Furthermore, after the slicing laser beam scanning is completed, the SiC crystal 10 has obtained the required modified layer, which is the dividing line between the SiC crystal 10 and the SiC wafer 11. At this point, further external force is needed to separate it from the SiC wafer 11. Further, the moving loading module 1 places the SiC crystal 10, after the required slicing laser beam scanning, directly below the slicing module. Under the control of the control module 6, the slicing module can be 100% adsorbed onto any surface (including planes and curved surfaces) of the SiC crystal 10. After adsorption, the control module 6 controls the slicing module to apply an upward instantaneous (0.01-0.05s) pulling force, causing the SiC crystal 10 and the SiC wafer 11 to separate at the modified layer, ultimately obtaining the SiC wafer 11, which is then bonded... Figure 5 At this time, the surface roughness of SiC wafer 11 is above Ra3μm.

[0110] Furthermore, it is necessary to test whether the SiC wafers 11 obtained by the above-mentioned segmentation are qualified. In this embodiment, the topography and size measurement module 8 is used to measure the segmented SiC wafers 11, and to check the surface macro / micro topography, warpage, flatness, curvature and surface roughness of the wafers 11. The measurement results are recorded by the control module 6 to prepare for the subsequent high-precision and high-efficiency laser polishing of the SiC wafers 11.

[0111] Furthermore, the robotic arm 9 places the SiC wafer 11 onto the loading module 1. Subsequently, the transfer module 2 transports the loading module 1 directly below the scanning galvanometer unit 42. Simultaneously, the optical path adjustment module 4 adjusts the optical path, and the control module 6 controls the polishing laser beam emitted by the laser generation module 3 to irradiate the upper and side surfaces of the SiC wafer 11 via the beam shaping unit 44 and the scanning galvanometer unit 42. Based on the measurement results of the topography and size measurement module 8, micron-level craters, fish-scale or hump-like structures, concave valley structures, and other macro / micro structures affecting surface roughness are selectively eliminated. By selectively polishing based on the measurement results of the topography and size measurement module 8, the processing efficiency of the SiC wafer 11 is improved.

[0112] Among them, macro / micro structures such as micron-scale craters and concave valley structures can be polished by laser polishing methods such as ablation and melting to reduce the surface roughness of SiC wafer 11; macro / micro structures that affect surface roughness, such as fish scales or camel humps, can be removed by laser polishing methods to reduce the surface roughness of SiC wafer 11.

[0113] It should be noted that the laser polishing process uses an ultraviolet femtosecond laser with a power of 1W-30W and a wavelength of 320nm, 336nm, 343nm, 355nm, 358nm, or 369nm, or an infrared femtosecond laser with a power of 5W-15W and a wavelength of 1030nm, 1046nm, 1056nm, 1060nm, 1064nm, or 1070nm. The polishing laser beam has a square or circular flat-top beam with a spot diameter of 25μm, 30μm, 35μm, 40μm, 45μm, or 50μm, and a pulse width of 20fs-320fs. Preferably, the laser polishing process involves 1-30 scans at a scanning speed of 0.5mm / s-3.5m / s, with a time interval of 1s-30s between each scan. In this laser polishing process, the loading module 1 can also achieve translation around the X and Y axes and rotation around the Z axis. Under the control of the control module 6, the scanning galvanometer unit 42 and the loading module 1 can achieve coordinated movement. The coordinated movement enables the scanning galvanometer unit 42 and the loading module 1 to meet the tracking performance of frequency and speed change trajectory. This enables the laser polishing laser beam to uniformly change speed on any predetermined processing trajectory and ensure the uniformity of the processed pattern.

[0114] Furthermore, whether the laser-polished SiC wafer 11 meets the requirements for the next step of chemical mechanical polishing needs further testing, combined with... Figure 6 This invention employs a morphology and dimensional measurement module 8 to measure the laser-polished SiC wafer 11, ensuring that the final laser-polished wafer 11 achieves optimal surface macro / micro morphology, warpage, curvature, and surface roughness. Its optical morphology and three-dimensional confocal image, i.e., the SiC wafer 11 obtained after laser polishing, exhibits complete surface macro / micro morphology, curvature ≤25µm, warpage ≤40µm, and surface roughness Ra ≤50nm, with a resistivity >1E5Ω·cm. If these requirements are not met, the laser polishing process needs to be repeated until the SiC wafer 11 reaches its optimal state. Based on the above description, a flowchart of the method for processing a SiC wafer 11 according to this invention can be obtained as follows: Figure 6 As shown, after laser polishing, the SiC wafer 11 has regular laser scanning marks on its surface. These marks are microscopically visible and can further improve the efficiency of subsequent chemical mechanical polishing. Since the SiC crystal 10 targeted by this invention can be no smaller than 6 inches, the scanning area of ​​the scanning galvanometer unit 42 cannot cover a SiC crystal 10 of this size. Therefore, continuous splicing scanning laser polishing of specific areas is necessary. However, splicing inevitably causes splicing stripes, affecting the subsequent laser slicing effect and processing efficiency. In this embodiment, by controlling the coordinated movement of the optical path adjustment module 4 and the loading module 1, the splicing stripes caused by splicing scanning laser polishing can be effectively avoided.

[0115] Thirdly, this embodiment provides a method for laser processing crystals, and the control module 6 in the laser processing crystal system described in any of the above aspects is applied. See [link to relevant documentation]. Figure 7 The method for laser processing crystals includes steps S101 to S104:

[0116] Step S101: Control the conveying module 2 to drive the loading module 1 to move the crystal 10 on the loading module 1 to the cutting station.

[0117] Step S102: Control the laser generating module 3 to emit a segmented laser beam, and control the optical path adjustment module 4 to move in coordination with the loading module 1 so that the segmented laser beam scans the crystal 10 at a uniform speed relative to the wafer 11 through the optical path adjustment module 4, forming a modified layer in the crystal 10.

[0118] Step S103: Control the transfer module 2 to drive the loading module 1 to move the crystal 10 on the loading module 1 to the slicing station.

[0119] Step S104: Control the wafer 11 separation module 5 to apply external force to the crystal 10 so as to separate the wafer 11 from the crystal 10 through the modified layer.

[0120] In an optional embodiment, the steps of controlling the laser generating module 3 to emit segmented laser beams and controlling the optical path adjustment module 4 to coordinate with the loading module 1 further include:

[0121] During the process of scanning the crystal 10 with a segmented laser beam, the imaging module 7 is controlled to monitor the burst points and / or cracks of the generated modified layer in order to obtain monitoring results.

[0122] Based on the monitoring results, determine whether it is necessary to adjust the processing parameters of the segmented laser beam to ensure that the modified layer meets the preset requirements.

[0123] In an optional embodiment, prior to the step of controlling the transfer module 2 to drive the loading module 1 to move the crystal 10 on the loading module 1 to the cutting station, the method for laser processing the crystal further includes:

[0124] The control transfer module 2 drives the loading module 1 to move the crystal 10 on the loading module 1 to the polishing station;

[0125] The laser generating module 3 controls the laser beam to be emitted and the optical path adjustment module 4 to move in coordination with the loading module 1 so that the laser beam polishes the surface of the crystal 10 at a uniform speed through the optical path adjustment module 4.

[0126] The morphology and size of the surface of the crystal 10 are measured by the morphology and size measurement module 8 to obtain the first measurement result;

[0127] Determine whether crystal 10 is qualified based on the first measurement result;

[0128] If the surface fails to meet the requirements, the control laser generating module 3 will emit a polishing laser beam to continue polishing the surface of the crystal 10.

[0129] If qualified, proceed with the step of moving the crystal 10 on loading module 1 to the cutting station;

[0130] After the step of controlling the wafer 11 separation module 5 to apply external force to the crystal 10 to separate the wafer 11 from the crystal 10 through the modified layer, the processing method further includes:

[0131] The morphology and dimensions of the wafer 11 surface are measured by the morphology and size measurement module 8 to obtain a second measurement result, and the polishing process parameters are determined based on the second measurement result.

[0132] The control transfer module 2 drives the loading module 1 to move the wafer 11 on the loading module 1 to the polishing station;

[0133] The laser generating module 3 controls the laser beam to be emitted and the optical path adjustment module 4 to move in coordination with the loading module 1 according to the polishing process parameters, so that the laser beam selectively passes through the optical path adjustment module 4 to polish the surface of the wafer 11 at a uniform speed.

[0134] The topography and dimensions of the wafer 11 surface are measured by the topography and dimension measurement module 8 to obtain the third measurement result;

[0135] Determine whether wafer 11 is qualified based on the third measurement result;

[0136] If it fails to meet the requirements, the control laser generating module 3 emits a polishing laser beam to continue polishing the surface of the wafer 11 until the wafer 11 is determined to be qualified.

[0137] This laser crystal processing method is simple to operate and can efficiently produce high-quality wafers 11.

[0138] In the description of this specification, the references to terms such as "some embodiments," "other embodiments," "ideal embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example that are included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0139] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0140] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A system for laser processing crystals, characterized in that, include: The loading module is used to load the crystal and move it. A conveying module is used to move the crystal between the cutting station and the slicing station via the loading module; Laser generating module, used to emit segmented laser beams; The optical path adjustment module is used to irradiate the crystal at the cutting station with the slicing laser beam and scan the crystal to form a modified layer inside the crystal. A wafer separation module is used to separate wafers from crystals through the modified layer; The control module is used to control the optical path adjustment module and the loading module to move in coordination when the optical path adjustment module controls the slicing laser beam to scan the crystal, so that the slicing laser beam scans the crystal at a uniform speed; The imaging module is used to monitor the burst points and / or cracks of the generated modified layer in real time during the scanning of the crystal by the slicing laser beam, so as to obtain the monitoring results; the control module is also used to determine whether the processing parameters of the slicing laser beam need to be adjusted according to the monitoring results obtained by real-time monitoring, so that the modified layer meets the preset requirements. The optical path adjustment module includes: an optical path switching unit, a scanning objective lens unit, and a scanning galvanometer unit; The scanning objective unit is used to irradiate the crystal at the cutting station with the slicing laser beam and scan the crystal to form a modified layer within the crystal; the scanning galvanometer unit is used to irradiate the crystal or wafer at the polishing station with the polishing laser beam and scan the crystal or wafer to polish the surface of the crystal or wafer. The optical path switching unit is electrically connected to the control module; the control module is also used to control the optical path switching unit to direct the segmented laser beam toward the scanning objective lens unit when the laser transmitting module emits a segmented laser beam, and to control the optical path switching unit to direct the polishing laser beam toward the scanning galvanometer unit when the laser transmitting module emits a polishing laser beam; The loading module, the transmission module, the laser generating module, the imaging module, the optical path adjustment module, and the wafer separation module are all electrically connected to the control module.

2. The system for laser processing a crystal as claimed in claim 1, wherein, The laser generating module is also used to emit a polishing laser beam; The conveying module is also used to move the crystal or wafer to the polishing station via the loading module; The scanning objective lens unit and the scanning galvanometer unit are respectively electrically connected to the control module; The control module is used to control the scanning objective lens unit and the loading module to move in coordination when the scanning objective lens unit controls the slicing laser beam to scan the crystal, and to control the scanning galvanometer unit and the loading module to move in coordination when the scanning galvanometer unit controls the polishing laser beam to scan the crystal or wafer, so that the polishing laser beam scans the surface of the crystal or wafer at a uniform speed.

3. The system for laser processing a crystal as defined in claim 2, wherein, The polishing laser beam is a Gaussian beam; The optical path adjustment module further includes: a beam shaping unit; The beam shaping unit is electrically connected to the control module; The beam shaping unit is used to transform the phase of a Gaussian beam into a flat-topped laser beam.

4. The system for laser-processing crystals according to claim 2, characterized in that, The optical path adjustment module further includes: a beam expander unit; The beam expander unit is fixedly positioned on the propagation path of the slicing laser beam and the polishing laser beam; The beam expander unit is used to increase the diameter of the slicing laser beam and the polishing laser beam.

5. The system for laser processing a crystal according to any one of claims 1 to 4, wherein The system for laser-processed crystals also includes: a morphology and size measurement module; The morphology and size measurement module is electrically connected to the control module; The morphology and size measurement module is used to measure the morphology and size of the crystal or wafer surface to obtain measurement results; The control module is used to determine whether a crystal or wafer is qualified based on the measurement results.

6. A method of laser processing a crystal, characterized by, A control module applied in a system for laser-processed crystals as described in any one of claims 1 to 5, comprising: The control conveying module drives the loading module to move the crystal on the loading module to the cutting station; The laser generating module is controlled to emit a segmented laser beam, and the optical path adjustment module and the loading module are controlled to move in coordination, so that the segmented laser beam scans the crystal at a uniform speed relative to the wafer through the optical path adjustment module, so as to form a modified layer in the crystal. The control and conveying module drives the loading module to move the crystal on the loading module to the slicing station; The control wafer separation module applies external force to the crystal to separate the wafer from the crystal through the modified layer.

7. The method for laser processing crystals according to claim 6, characterized in that, The step of controlling the laser generating module to emit segmented laser beams and controlling the optical path adjustment module to coordinate with the loading module further includes: During the process of scanning the crystal with a segmented laser beam, the imaging module is controlled to monitor the burst points and / or cracks of the generated modified layer in order to obtain monitoring results; Based on the monitoring results, determine whether it is necessary to adjust the processing parameters of the segmented laser beam to ensure that the modified layer meets the preset requirements.

8. The method of claim 6, wherein the laser processing crystal is a YVO4 crystal. Prior to the step where the control and transfer module drives the loading module to move the crystal on the loading module to the cutting station, the method for laser processing the crystal further includes: The control and conveying module drives the loading module to move the crystal on the loading module to the polishing station; The laser generating module is controlled to emit a polishing laser beam, and the optical path adjustment module and the loading module are controlled to move in coordination so that the polishing laser beam polishes the surface of the crystal at a uniform speed through the optical path adjustment module. The morphology and size of the crystal surface are measured using a morphology and size measurement module to obtain the first measurement result; Determine whether the crystal is qualified based on the first measurement result; If the result is unsatisfactory, the control laser generation module emits a polishing laser beam to continue polishing the surface of the crystal; If successful, proceed with the step of moving the crystal on the loading module to the cutting station; After the step of the control wafer separation module applying external force to the crystal to separate the wafer from the crystal through the modified layer, the processing method further includes: The morphology and dimensions of the wafer surface are measured by a morphology and size measurement module to obtain a second measurement result, and the polishing process parameters are determined based on the second measurement result. The control transfer module drives the loading module to move the wafer on the loading module to the polishing station; The laser generating module is controlled to emit a polishing laser beam, and the optical path adjustment module and the loading module are controlled to move in coordination according to the polishing process parameters, so that the polishing laser beam selectively passes through the optical path adjustment module to polish the surface of the wafer at a uniform speed; The morphology and dimensions of the wafer surface are measured using a morphology and dimension measurement module to obtain a third measurement result; The wafer's quality is determined based on the third measurement result. If the wafer fails to meet the requirements, the laser generator module will emit a polishing laser beam to continue polishing the surface of the wafer until it is determined to be qualified.

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