Wafer edge processing apparatus and method

Abstract

The application provides a wafer edge processing device and a method thereof. The wafer edge processing device comprises a laser system and a cutting assembly. The laser system applies a first laser beam to a surface layer region to perform a local thermal modification treatment on the surface layer region to form a first thermal treatment layer. The laser system applies a second laser beam to an internal region, and the energy of the second laser beam is distributed in a gradient along the thickness direction of the wafer to perform a gradient thermal modification treatment on the internal region to form a second thermal treatment layer. The first thermal treatment layer and the second thermal treatment layer form a composite modification region with a preset thermal gradient distribution, and the hardness of the composite modification region changes in a gradient along the thickness direction of the wafer. The application forms a gradient modification layer with gradually changing hardness from the outside to the inside through the synergistic effect of the two laser beams on the wafer edge, can realize the synergistic regulation and control of wafer edge surface layer softening and internal gradient modification, and can improve the stability of wafer edge trimming and edge integrity.

Description

Technical Field

[0001] This application relates to the technical field of wafer edge processing, and more specifically, to a wafer edge processing apparatus and method. Background Technology

[0002] In the semiconductor manufacturing industry, wafer thinning is one of the important processes before chip packaging. Before wafer thinning, the wafer edges need to be trimmed to eliminate cracks and scratches on the wafer periphery. The quality of wafer edge processing directly affects the chip's performance and yield.

[0003] Currently, wafer edge processing methods mainly include traditional cutting and laser processing. However, the inventors of this application have discovered that traditional cutting methods use physical cutter heads for edge trimming. Due to the high hardness and brittleness of wafer materials, direct contact between the cutter head and the edge trimming head can easily cause cracks, breakage, and uneven trimming, thus affecting the wafer processing quality.

[0004] Laser processing typically uses a single laser beam to preheat or locally modify the wafer edges to reduce cutting resistance from subsequent tooling. In single-laser processing, laser energy is concentrated on the surface, making it difficult to stably control the heat-affected zone (HAZ), which can easily lead to overheating, deep crack propagation, and uneven modification. Especially during high-speed continuous wafer rotation, a single heat source results in an unstable thermal gradient distribution and uneven residual stress, increasing the risk of edge chipping and edge contour fluctuations during subsequent tooling trimming. Furthermore, multi-laser beam processing focuses on layer-by-layer peeling and lacks coordinated control over surface softening and deep modification.

[0005] The content in the background section is merely technology known to the public and does not necessarily represent existing technology in this field. Summary of the Invention

[0006] This application provides a wafer edge processing apparatus and method, which aims to solve at least one of the technical problems mentioned in the background art.

[0007] According to one aspect of this application, a wafer edge processing apparatus is provided, including a laser system and a cutting assembly. The laser system performs dual-path laser-assisted thermal processing on a target edge region of the wafer, the target edge region including at least partially overlapping surface and internal regions. The laser system applies a first laser beam to the surface region to locally thermally modify the surface region, forming a first thermally treated layer. The laser system also applies a second laser beam to the internal region, the energy of the second laser beam being gradient-distributed along the thickness direction of the wafer to perform gradient thermal modification on the internal region, forming a second thermally treated layer. The first and second thermally treated layers form a composite modified region with a predetermined thermal gradient distribution, and the hardness of the composite modified region varies gradient along the thickness direction of the wafer. The cutting assembly cuts the composite modified region along the tangential direction of the wafer to remove edge material of the composite modified region having a target thickness.

[0008] According to some embodiments of this application, the laser system includes: a spatial light modulation unit disposed in the optical path of a second laser beam to adjust the energy density of the cross section of the second laser beam, such that the energy density of the second laser beam is gradient-distributed along the thickness direction of the wafer.

[0009] According to some embodiments of this application, the spatial light modulation unit adjusts the transmittance of different regions of the second laser beam cross section to control the energy density of the second laser beam cross section.

[0010] According to some embodiments of this application, the spatial light modulation unit performs energy differential attenuation on different regions of the second laser beam cross section in order to control the energy density of the second laser beam cross section.

[0011] According to some embodiments of this application, the pulses of the first laser beam are output synchronously with the pulses of the second laser beam; or the pulses of the second laser beam have a first preset time interval relative to the pulses of the first laser beam; or the first laser beam and the second laser beam are output in an alternating pulse sequence, with a second preset time interval between adjacent pulses.

[0012] According to some embodiments of this application, a laser system includes: a light source that emits a laser beam; and a beam splitting unit that splits the laser beam into a first laser beam and a second laser beam.

[0013] According to some embodiments of this application, the laser system further includes: a first polarization unit disposed in the optical path of the first laser beam to apply the first laser beam to the surface region; a first lens disposed between the first polarization unit and the surface region; a second polarization unit disposed in the optical path of the second laser beam to apply the second laser beam to the inner region; and a second lens disposed between the second polarization unit and the inner region.

[0014] According to some embodiments of this application, the composite modified region includes a first modified segment and a second modified segment. The first modified segment extends from the surface layer of the composite modified region along the thickness direction of the wafer to a first depth, and the hardness of the first modified segment is the same along the thickness direction of the wafer. The second modified segment extends from the first depth along the thickness direction of the wafer to a second depth, and the hardness of the second modified segment varies in a gradient along the thickness direction of the wafer.

[0015] According to some embodiments of this application, the first depth accounts for 40% to 60% of the target thickness.

[0016] According to another aspect of this application, a wafer edge processing method is provided, comprising: applying a first laser beam to a surface region to perform local thermal modification processing on the surface region to form a first heat treatment layer; applying a second laser beam to an inner region, the energy of the second laser beam being gradient-distributed along the thickness direction of the wafer to perform gradient thermal modification processing on the inner region to form a second heat treatment layer, the first heat treatment layer and the second heat treatment layer forming a composite modified region with a preset thermal gradient distribution, the hardness of the composite modified region varying gradient along the thickness direction of the wafer; and cutting the composite modified region along the tangent direction of the wafer to remove edge material of the composite modified region having a target thickness.

[0017] According to some embodiments of this application, applying a second laser beam to an internal region, wherein the energy of the second laser beam is gradient-distributed along the thickness direction of the wafer, to perform gradient thermal modification treatment on the internal region includes: adjusting the energy density of the cross-section of the second laser beam so that the energy density of the second laser beam is gradient-distributed along the thickness direction of the wafer.

[0018] According to some embodiments of this application, adjusting the energy density of the second laser beam cross section such that the energy density of the second laser beam is gradient distributed along the thickness direction of the wafer includes: adjusting the transmittance of different regions of the second laser beam cross section to control the energy density of the second laser beam cross section.

[0019] According to some embodiments of this application, adjusting the energy density of the second laser beam cross section so that the energy density of the second laser beam is gradient distributed along the thickness direction of the wafer includes: performing energy differential attenuation on different regions of the second laser beam cross section to control the energy density distribution of the second laser beam cross section.

[0020] According to some embodiments of this application, the pulses of the first laser beam are output synchronously with the pulses of the second laser beam; or the pulses of the second laser beam have a first preset time interval relative to the pulses of the first laser beam; or the first laser beam and the second laser beam are output in an alternating pulse sequence, with a second preset time interval between adjacent pulses.

[0021] According to some embodiments of this application, the composite modified region includes a first modified segment and a second modified segment. The first modified segment extends from the surface layer of the composite modified region along the thickness direction of the wafer to a first depth, and the hardness of the first modified segment is the same along the thickness direction of the wafer. The second modified segment extends from the first depth along the thickness direction of the wafer to a second depth, and the hardness of the second modified segment varies in a gradient along the thickness direction of the wafer.

[0022] According to some embodiments of this application, the first depth accounts for 40% to 60% of the target thickness.

[0023] Beneficial effects This application employs two laser beams with different functions to perform synergistic thermal modification of the wafer edge. The first laser beam locally thermally modifies the surface region of the wafer edge, softening the surface material and forming a first heat-treated layer with reduced hardness, thus lowering the initial cutting resistance during subsequent trimming. The second laser beam applies a gradient energy density along the wafer's thickness direction to the internal region, controlling the thermal gradient and creating a gradient energy distribution. The first and second heat-treated layers together form a composite modified region with a preset thermal gradient distribution. Along the wafer's thickness, the hardness of this composite modified region gradually changes from the outside to the inside, forming a gradient modified layer structure that gradually transitions from a low-hardness softened area to a high-integrity unmodified area. The cutting assembly cuts along the wafer tangent direction into the composite modified region, removing edge material of the target thickness, thereby completing the wafer edge trimming process.

[0024] This application utilizes the synergistic effect of two laser beams to form a gradient modification layer with gradually changing hardness from the outside to the inside at the wafer edge. This effectively avoids problems such as local overheating, uneven thermal impact, and deep microcrack propagation that are prone to occur in traditional single-laser processing, thereby improving the stability and edge integrity of wafer edge trimming.

[0025] This application pre-constructs a gradient thermally modified region at the wafer edge, allowing the material hardness of the cutting component to gradually transition during the cutting process. This enables a smoother transmission of cutting loads, effectively mitigating localized stress concentration caused by material brittleness during mechanical trimming and reducing the risk of edge chipping and microcrack propagation. Simultaneously, the gradient thermally affected layer stabilizes the cutting state of the cutting component, reducing cutting force fluctuations and improving the consistency and surface quality of the wafer edge profile. Furthermore, since the composite modified region is limited to the area to be trimmed, it ensures improved wafer edge surface quality and profile accuracy while maintaining the integrity of the main wafer structure, thus enabling low-damage, high-precision wafer edge trimming. This application achieves synergistic control of wafer edge surface softening and internal gradient modification, significantly improving wafer edge trimming quality and processing stability. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0027] Figure 1 This diagram illustrates the structure of a wafer edge processing apparatus according to an embodiment of this application. Figure 2a This invention provides a schematic diagram of the wafer structure according to an embodiment of the present application. Figure 2b This diagram shows a cross-sectional view of a wafer according to an embodiment of this application. Figure 3 This invention provides a schematic diagram of the structure of a laser system according to an embodiment of the present application. Figure 4 A pulse diagram illustrating the first and second laser beams according to an embodiment of this application is shown. Figure 5 A schematic flowchart of a wafer edge processing method according to an embodiment of this application is shown.

[0028] Explanation of reference numerals in the attached figures: Laser system 10; cutting assembly 20; wafer 30; rotary table 40; Surface region L1; Internal region L2; Overlapping region N; First laser beam R1; Second laser beam R2; Spatial light modulation unit 11; light source 12; beam splitting unit 13; first polarization unit 14; first lens 15; second polarization unit 16; second lens 17. Detailed Implementation

[0029] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this application will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0030] The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of these specific details, or other methods, components, materials, devices, etc. In these cases, well-known structures, methods, devices, implementations, materials, or operations will not be shown or described in detail.

[0031] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0032] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order.

[0033] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] Currently, wafer edge processing methods mainly include traditional cutting methods and laser processing methods.

[0035] For example, when using traditional cutting methods to trim wafer edges, tool wear is significantly accelerated for ultra-thin or brittle wafers, leading to a continuous decline in edge trimming quality. Frequent tool changes not only increase production costs but also extend equipment downtime. Furthermore, the cutter head directly cutting the wafer edge can easily create micro-cracks in the edge area, potentially causing wafer breakage and directly impacting product reliability and production yield. Additionally, when the trimming depth is large, the cutter head struggles to maintain consistent trimming quality across the entire depth range, making it impossible to effectively guarantee the uniformity of the wafer edge contour.

[0036] For example, when using laser processing to trim wafer edges, the laser power needs to be adjusted according to the wafer's material thickness and properties. However, the current precision in controlling laser power is insufficient, easily leading to problems such as excessively deep melting zones or uneven edge trimming depth, thus affecting the trimming effect. Furthermore, during laser heating, the melting depth is affected by multiple factors, including the laser beam focal position, power, and irradiation time. These factors are interrelated, making it difficult to precisely and stably control the melting zone depth, thus limiting the consistency of wafer edge processing.

[0037] According to one aspect of this application, a wafer edge processing apparatus is provided.

[0038] According to the example embodiment, such as Figure 1 As shown, the wafer edge processing device includes a laser system 10 and a cutting assembly 20. The wafer 30 is mounted on a rotary table 40 and can rotate at a set speed under the drive of the rotary table 40.

[0039] like Figure 1 or Figure 2a As shown, the laser system 10 performs dual-path laser-assisted thermal processing on the target edge region L of the wafer 30. For example... Figure 2b As shown, along the thickness direction D of wafer 30 (i.e., along the direction perpendicular to the horizontal plane), the target edge region L includes at least partially overlapping surface region L1 and internal region L2. Figure 2b N in the diagram represents the overlapping area of ​​the surface region L1 and the internal region L2.

[0040] For example, surface region L1 refers to the area with a certain thickness on the edge surface of wafer 30, and inner region L2 refers to the inner region of the wafer located below surface region L1. Surface region L1 and inner region L2 at least partially overlap in space to ensure that the subsequently formed first and second heat treatment layers can form a continuous composite modified region, which can avoid unmodified gaps between layers that could lead to stress concentration or crack propagation during the cutting process.

[0041] like Figure 1 , Figure 2a or Figure 2b As shown, the laser system 10 applies (e.g., vertically) a first laser beam R1 to the surface region L1 to perform local thermal modification treatment on the surface region L1, forming a first heat-treated layer.

[0042] For example, the focusing position of the first laser beam R1 can be located in the middle of the surface region L1, and its energy density can cause local thermal modification of the material in the surface region L1. After the surface region L1 is irradiated by the first laser beam R1, the material hardness decreases, forming a softened layer, which can reduce the cutting resistance during subsequent cutting by the cutting component 20, and at the same time improve the stress state of the surface region L1, and suppress the generation of surface microcracks.

[0043] Optionally, the irradiation direction of the first laser beam R1 is not limited to vertical irradiation, but can also be incident at a certain tilt angle relative to the surface of the wafer 30, so that the energy deposition distribution of the first laser beam R1 in the surface region L1 can be controlled.

[0044] This application uses a first laser beam R1 to perform local thermal modification on the surface region L1 of the wafer 30, which can form a first thermal treatment layer with reduced hardness on the wafer edge surface, providing a pretreatment basis for the second laser treatment in the subsequent dual-laser collaborative modification and wafer edge cutting.

[0045] According to the example embodiment, such as Figure 1 , Figure 2a or Figure 2b As shown, the laser system 10 applies a second laser beam R2 to the internal region L2. The energy of the second laser beam R2 is distributed in a gradient along the thickness direction D of the wafer 30 to perform gradient thermal modification treatment on the internal region L2, forming a second heat treatment layer. The first heat treatment layer and the second heat treatment layer form a composite modified region with a preset thermal gradient distribution. The hardness of the composite modified region changes in a gradient along the thickness direction D of the wafer 30.

[0046] For example, the laser system 10 can apply a second laser beam R2 to the internal region L2 in a horizontal direction. Different regions of the cross-section of the second laser beam R2 have different energy densities, thus forming a gradient energy density distribution along the thickness direction D of the wafer 30. The irradiation position of the second laser beam R2 has a preset radial offset relative to the edge of the wafer 30, so that the second laser beam R2 can accurately act on the internal region L2 to perform gradient thermal modification treatment on the internal region L2. After the second laser beam R2 performs gradient thermal modification treatment on the internal region L2, a second heat treatment layer is formed. Since the energy density of the second laser beam R2 is gradient distributed along the thickness direction D of the wafer 30, the degree of modification of the second heat treatment layer also varies gradient along this thickness direction D.

[0047] For example, the hardness of the composite modified region gradually transitions from low to high from the surface region L1 to the inner region L2. This hardness gradient can eliminate the abrupt performance interface between the modified and unmodified regions, allowing the cutting load of the subsequent cutting component 20 to be transmitted smoothly during the cutting process, thus avoiding stress concentration and crack propagation caused by abrupt hardness changes.

[0048] This can be understood as follows: in the existing single-laser preheating technology, the laser beam is incident along the thickness direction of the wafer, and the energy decays exponentially along the thickness direction. The gradient distribution of the heat-affected zone is passively determined by the Beer-Lambert law and the heat conduction equation. The gradient shape is fixed as an exponential decay type and cannot be independently controlled. In essence, it is a "passive gradient".

[0049] This application, by independently adjusting the energy attenuation or transmittance of different regions of the cross-section of the second laser beam R2, allows the energy density of the second laser beam R2 along the thickness direction to be preset as linear, stepwise, or any specific curve as needed. Combined with the independent softening of the surface region L1 by the first laser beam R1, dual regulation of surface modification and internal modification can be achieved, changing the formation mechanism of the hardness gradient from "passive acceptance" to "active regulation." The synergistic superposition of the two heat sources can make the hardness distribution curve of the composite modification region a programmable and optimizable "active gradient."

[0050] This application, through the "active gradient" setting of the hardness distribution in the composite modified region, can, on the one hand, customize the optimal hardness transition curve according to the cutting mechanics requirements: the surface layer is sufficiently softened to reduce initial cutting resistance, while the internal hardness gradually increases to uniformly transmit cutting loads, thereby significantly reducing cutting force fluctuations and the risk of edge chipping. On the other hand, it can eliminate the abrupt performance interface between the modified and unmodified regions, preventing crack propagation along the interface.

[0051] Optionally, the irradiation width and depth of the first laser beam R1 and the second laser beam R2 can be customized according to process requirements.

[0052] Optionally, the gradient distribution of the energy density of the second laser beam R2 along the thickness direction D of the wafer 30 is not limited to a linear change, but can also be a nonlinear change, a step change, or other preset distribution pattern changes, which can be customized according to process requirements.

[0053] Optionally, the irradiation direction of the second laser beam R2 can be horizontally incident from the side of the edge of the wafer 30, or incident at a certain angle from above or below the edge. As long as the second laser beam R2 can effectively act on the internal region L2, this application does not impose any restrictions on this.

[0054] This application uses a second laser beam R2 to perform gradient thermal modification on the internal region L2 of the wafer 30, which can form a second heat treatment layer inside the wafer edge. Together with the first heat treatment layer, it can form a composite modification region with a gradient change in hardness along the thickness direction D of the wafer 30. This can achieve synergistic control of wafer edge surface softening and internal gradient modification, thereby effectively avoiding the problems of local overheating, uneven thermal influence, and deep microcrack propagation that are prone to occur in traditional single laser processing.

[0055] According to the example embodiment, the cutting component 20 cuts the composite modified region along the tangent direction of the wafer 30 to remove the edge material of the composite modified region having a target thickness.

[0056] For example, while the rotary table 40 drives the wafer 30 to rotate around its central axis, the cutting assembly 20 can feed along the radial direction of the wafer 30, causing the outer edge of the cutting assembly 20 to contact the composite modification region. Because the rotational motion of the wafer 30 coordinates with the rotational motion of the cutting assembly 20, the cutting assembly 20 generates a relative motion with respect to the target edge region L of the wafer 30 along the tangential direction, thereby enabling the cutting of the composite modification region along the tangential direction of the wafer 30.

[0057] During the cutting process, because the hardness of the composite modified region varies gradient along the thickness direction D (low surface hardness, high internal hardness), the cutting resistance is small and stable when the cutting component 20 cuts into the surface. As the cutting depth gradually increases, the cutting resistance increases gradually. The cutting load can be transmitted smoothly throughout the entire cutting process, with minimal fluctuations in cutting force, effectively avoiding localized stress concentration and edge chipping caused by material brittleness during traditional mechanical trimming. After cutting, the edge material of the composite modified region with the target thickness (which can be determined according to wafer size and process requirements) is completely removed, thus achieving low-damage, high-stability wafer edge trimming.

[0058] This application employs two laser beams with different functions to perform synergistic thermal modification of the wafer edge. The first laser beam locally thermally modifies the surface region of the wafer edge, softening the surface material and forming a first heat-treated layer with reduced hardness, thus lowering the initial cutting resistance during subsequent trimming. The second laser beam applies a gradient energy density along the wafer's thickness direction to the internal region, controlling the thermal gradient and creating a gradient energy distribution. The first and second heat-treated layers together form a composite modified region with a preset thermal gradient distribution. Along the wafer's thickness, the hardness of this composite modified region gradually changes from the outside to the inside, forming a gradient modified layer structure that gradually transitions from a low-hardness softened area to a high-integrity unmodified area. The cutting assembly cuts along the wafer tangent direction into the composite modified region, removing edge material of the target thickness, thereby completing the wafer edge trimming process.

[0059] This application utilizes the synergistic effect of two laser beams to form a gradient modification layer with gradually changing hardness from the outside to the inside at the wafer edge. This effectively avoids problems such as local overheating, uneven thermal impact, and deep microcrack propagation that are prone to occur in traditional single-laser processing, thereby improving the stability and edge integrity of wafer edge trimming.

[0060] This application pre-constructs a gradient thermally modified region at the wafer edge, allowing the material hardness of the cutting component to gradually transition during the cutting process. This enables a smoother transmission of cutting loads, effectively mitigating localized stress concentration caused by material brittleness during mechanical trimming and reducing the risk of edge chipping and microcrack propagation. Simultaneously, the gradient thermally affected layer stabilizes the cutting state of the cutting component, reducing cutting force fluctuations and improving the consistency and surface quality of the wafer edge profile. Furthermore, since the composite modified region is limited to the area to be trimmed, it ensures improved wafer edge surface quality and profile accuracy while maintaining the integrity of the main wafer structure, thus enabling low-damage, high-precision wafer edge trimming. This application achieves synergistic control of wafer edge surface softening and internal gradient modification, significantly improving wafer edge trimming quality and processing stability.

[0061] Optionally, the composite modification region includes a first modification segment and a second modification segment. The first modification segment extends from the surface layer of the composite modification region along the thickness direction of the wafer 30 to a first depth, and the hardness of the first modification segment is the same along the thickness direction of the wafer 30. The second modification segment extends from the first depth along the thickness direction of the wafer 30 to a second depth, and the hardness of the second modification segment varies in a gradient along the thickness direction of the wafer 30.

[0062] For example, by compensatoryly modulating the cross-sectional energy density distribution of the second laser beam R2, the energy density of the second laser beam R2 within the corresponding depth range of the first modification segment exhibits a distribution pattern opposite to the passive thermal gradient of the first laser beam R1. This can compensate for the abrupt change in surface hardness of the first laser beam R1, ensuring that the hardness within the first depth range remains essentially consistent after the superposition of the two thermal modification effects. This configuration ensures that in the initial stage of cutting, the cutting component 20 first encounters the first modification segment with no abrupt change in hardness, guaranteeing a stable and impact-free initial cutting force.

[0063] The second modified section extends from the first depth along the thickness direction of wafer 30 to the second depth, and the hardness along this thickness direction exhibits a preset active gradient change (e.g., a linear gradient or a step gradient). This configuration allows the composite modified region to smoothly transition from the end of the first modified section to the original hardness of the unmodified region of the wafer, eliminating the abrupt performance interface between the composite modified region and the unmodified region of the wafer, and reducing stress concentration and crack propagation risks during the cutting process.

[0064] Optionally, the first depth accounts for 40% to 60% of the target thickness.

[0065] For example, the first depth can be set to 40% to 60% of the target thickness. When the cutting assembly 20 begins to cut from the edge surface of the wafer 30, the first 40% to 60% of its total feed corresponds to the cutting process of the first modification segment. The hardness of this segment is basically consistent, which can ensure that the cutting force is stable and without jumps in the initial and intermediate stages of cutting. The remaining 40% to 60% of the feed corresponds to the cutting process of the second modification segment. The hardness of this segment changes actively, smoothly transitioning from the hardness of the first modification segment to the original hardness of the unmodified area of ​​the wafer. This can eliminate the interface of abrupt performance changes, allowing the cutting load to be smoothly transmitted throughout the cutting process, thus meeting the dual requirements of cutting consistency and low-damage finishing.

[0066] Optionally, such as Figure 3 As shown, the laser system 10 may include a spatial light modulation unit 11. The spatial light modulation unit 11 is disposed in the optical path of the second laser beam R2 to adjust the energy density of the cross section of the second laser beam R2, so that the energy density of the second laser beam R2 is gradient distributed along the thickness direction D of the wafer 30.

[0067] For example, such as Figure 3 As shown, the spatial light modulation unit 11 is disposed in the optical path of the second laser beam R2. Its function is to spatially shape the energy density distribution of the beam cross section before the second laser beam R2 irradiates the wafer 30.

[0068] The spatial light modulation unit 11 can apply independently controllable transmittance or attenuation rate to different regions of the beam cross section, so that different regions of the beam cross section corresponding to the thickness direction D of the wafer 30 obtain different energy transmission ratios, thereby adjusting the second laser beam R2, which originally had a relatively uniform cross section energy distribution, into a beam with a preset energy gradient distribution along the thickness direction D of the wafer.

[0069] This application, through the configuration of a spatial light modulation unit, enables the energy density of the second laser beam along the thickness direction of the wafer to continuously vary according to a preset rule (such as gradually increasing, gradually decreasing, nonlinear change, or step change). This configuration allows for differentiated heating of the wafer along its thickness direction when the modulated second laser beam is incident on the internal region, thereby forming a second heat treatment layer with a gradient of modification degree in the internal region. This enables precise control over the depth and thermal gradient distribution of the heat-affected layer.

[0070] Optionally, the spatial light modulation unit 11 adjusts the transmittance of different regions of the cross section R2 of the second laser beam to control the energy density of the cross section R2 of the second laser beam.

[0071] For example, the spatial light modulation unit 11 (such as a transmissive liquid crystal spatial light modulator) may include multiple independently addressed pixel units, each of which can independently control its transmittance (i.e., the percentage of incident light intensity that is allowed to pass through).

[0072] When the second laser beam R2 passes through the spatial light modulation unit 11, different regions on the beam cross-section correspond to different pixel units of the spatial light modulation unit 11. The control module of the spatial light modulation unit 11 can apply different driving signals to each pixel unit according to a preset energy gradient distribution function, so that each pixel unit has different transmittance. After the second laser beam R2 passes through the spatial light modulation unit 11, the light intensity of different regions of its cross-section is differentially processed, thereby forming an energy density distribution with a gradient along the thickness direction D of the wafer.

[0073] This application can control the transmittance of different regions of the second laser beam cross section through a spatial light modulation unit. It does not require changing the output characteristics of the laser system. The energy density distribution of the second laser beam cross section can be flexibly and accurately controlled simply by spatially modulating the transmittance. It has the advantages of convenient process adjustment and fast response speed.

[0074] Optionally, the spatial light modulation unit 11 performs energy differential attenuation on different regions of the second laser beam R2 cross section to control the energy density of the second laser beam R2 cross section.

[0075] For example, the spatial light modulation unit 11 can control the attenuation of the laser beam by adjusting the gray level of each pixel unit, so that the energy density distribution of the second laser beam R2 is reshaped on its cross-section after passing through the spatial light modulation unit 11, forming an energy gradient distribution along the thickness direction D of the wafer 30. Through differential energy attenuation, the spatial light modulation unit 11 can selectively absorb, reflect, or scatter light energy in different regions of the cross-section of the second laser beam R2, so that the remaining energy transmitted in different regions is different, thereby realizing the spatial shaping of the energy density of the second laser beam R2.

[0076] This application can achieve differentiated energy attenuation in different regions of the second laser beam cross section through a spatial light modulation unit. This energy differential attenuation method does not require changing the output parameters of the laser system. It can accurately adjust the energy density of the second laser beam cross section simply by introducing a controllable spatial attenuation distribution in the optical path. It has the characteristics of simple structure, flexible adjustment and fast response speed.

[0077] Optionally, the pulses of the first laser beam R1 are output synchronously with the pulses of the second laser beam R2.

[0078] For example, such as Figure 4 As shown in the synchronous pulse output, when the pulse of the first laser beam R1 is output synchronously with the pulse of the second laser beam R2, the rising edge of the pulse of the first laser beam R1 is aligned with the rising edge of the pulse of the second laser beam R2 in time, and the pulse width and repetition frequency of the two laser beams are consistent, so that the first laser beam R1 and the second laser beam R2 irradiate the surface region L1 and the internal region L2 of the wafer 30 at the same time.

[0079] This application enables the surface and internal regions to be irradiated by laser at the same time through synchronous output. The two heat sources simultaneously heat-treat the target edge region, and the thermal fields of the surface region and the internal region are established and coupled with each other at the same time. This can form an instantaneously stable thermal gradient distribution along the thickness direction at the wafer edge, which is beneficial to forming a composite modified region with continuous transition of hardness along the thickness direction under the synergistic effect of the two laser beams.

[0080] Optionally, the pulses of the second laser beam R2 have a first preset time interval Δt1 relative to the pulses of the first laser beam R1.

[0081] For example, such as Figure 4 As shown in the delayed pulse output, the first laser beam R1 and the second laser beam R2 are not output simultaneously, but are output sequentially according to a preset timing relationship. The pulse of the first laser beam R1 and the pulse of the second laser beam R2 are separated by a first preset time interval Δt1 (the specific value is determined according to the thermal diffusivity of the wafer material and the modification depth requirements).

[0082] For example, a first laser beam R1 may first emit a pulse to irradiate the surface region L1, and after a first preset time interval Δt1, a second laser beam R2 may then emit a pulse to irradiate the inner region L2. Alternatively, the second laser beam R2 may first emit a pulse to preprocess the inner region L2, and after a first preset time interval Δt1, the first laser beam R1 may then emit a pulse to irradiate the surface region L1.

[0083] This application, by setting a first preset time interval, allows the wafer edge material to have a buffer period for thermal diffusion or thermal relaxation during the processing of two laser beams. The first arriving laser pulse can establish an initial temperature field at the wafer edge. After thermal conduction over the first preset time interval, the initial temperature field diffuses along the thickness direction to a predetermined depth. When the second laser pulse arrives, it can be superimposed on the diffused thermal field, thereby accurately controlling the final depth and thermal gradient distribution of the heat-affected layer.

[0084] Optionally, the first laser beam R1 and the second laser beam R2 are output in an alternating pulse sequence, with a second preset time interval between adjacent pulses.

[0085] The first laser beam R1 and the second laser beam R2 can emit pulses in an alternating sequence to form a pulse sequence.

[0086] For example, such as Figure 4 As shown in the alternating pulse sequence output, the first laser beam R1 emits a pulse to irradiate the surface region L1. After a second preset time interval Δt2, the second laser beam R2 emits a pulse to irradiate the inner region L2. After another second preset time interval Δt2, the first laser beam R1 emits another pulse to irradiate the surface region L1. This alternation continues until a predetermined number of pulses are output.

[0087] For example, the value of the second preset time interval Δt2 can be the same as or different from the first preset time interval Δt1, depending on the thermal diffusion characteristics of the wafer material, the modification depth requirements, and the setting of the number of pulses.

[0088] This application uses an alternating pulse sequence output method to allow the surface and internal regions to be irradiated by laser alternately. Each pulse adds a new heat input on the thermal field established by the previous pulse. Through multiple, gradual alternating heating, the temperature rise rate and heat accumulation degree at the wafer edge can be accurately controlled, avoiding thermal shock damage caused by a single large energy input.

[0089] Optionally, such as Figure 3As shown, the laser system 10 also includes a light source 12 and a beam splitting unit 13. The light source 12 emits a laser beam, and the beam splitting unit 13 splits the laser beam into a first laser beam R1 and a second laser beam R2.

[0090] For example, the light source 12 can be a laser, such as a solid-state laser, fiber laser, or gas laser, which is a laser generating device capable of outputting a high-energy-density laser beam. The output power, pulse width, and repetition frequency of the light source 12 can be adjusted according to process requirements.

[0091] like Figure 3 As shown, the beam splitting unit 13 is disposed in the output optical path of the light source 12, and is used to split a laser beam emitted by the light source 12 into a first laser beam R1 and a second laser beam R2 according to a preset beam splitting ratio (e.g., 1:1, 1:2 or other ratio). After beam splitting, the first laser beam R1 and the second laser beam R2 are transmitted through their respective output paths and applied to the surface region L1 and the internal region L2 of the wafer 30, respectively.

[0092] For example, the beam splitting unit 13 may be an optical element such as a beam splitting prism (which controls the energy ratio of the two outgoing beams by the beam splitting ratio of the film reflectivity and transmittance), a partial reflector (which distributes energy proportionally between the transmitted light and the reflected light), or an optical fiber beam splitter (which distributes the laser in the input optical fiber to the two output optical fibers proportionally).

[0093] By setting up a beam splitter, this application enables the first and second laser beams to be generated from the same light source, so that the two laser beams have the same wavelength, pulse timing reference and coherence. This is beneficial to the timing synchronization and thermal field coupling consistency of the two laser beams during collaborative processing. At the same time, only one light source is needed to achieve dual-path laser output, which can reduce equipment cost and system complexity.

[0094] Optionally, such as Figure 3 As shown, the laser system 10 also includes a first polarization unit 14 and a first lens 15. The first polarization unit 14 is disposed in the optical path of the first laser beam R1 to apply the first laser beam R1 to the surface region L1. The first lens 15 is disposed between the first polarization unit 14 and the surface region L1.

[0095] For example, the first polarization unit 14 is disposed on the transmission optical path after the first laser beam R1 is split by the beam splitting unit 13, and is used to adjust the polarization state of the first laser beam R1. The first polarization unit 14 includes, but is not limited to, polarizing optical elements such as polarizers, half-wave plates, quarter-wave plates or polarizing beam splitters.

[0096] Since wafer materials (especially semiconductor materials) have different absorption rates and thermal effects on lasers with different polarization states, the polarization state of the first laser beam R1 can be adjusted by the first polarization unit 14 (for example, adjusting linearly polarized light to circularly polarized light or ellipsoidally polarized light, or adjusting the polarization direction of linearly polarized light), thereby optimizing the energy coupling efficiency and thermal distribution of the first laser beam R1 in the surface region L1 of the wafer 30, so that the surface region L1 can obtain the expected thermal modification effect.

[0097] The first lens 15 is positioned after the first polarization unit 14 and before the surface region L1 of the wafer 30, and is used to focus the polarization-adjusted first laser beam R1 onto the surface region L1. For example, the first lens 15 can be an F-theta lens, which can focus the incident laser beam into a spot of a preset size and maintain uniform focusing characteristics of the focal point within the scanning plane, thereby ensuring that the first laser beam R1 forms a stable and uniform irradiation spot on the surface of the wafer 30.

[0098] This application enables the first laser beam to be precisely applied to the surface region of the wafer with optimized polarization and focusing by the coordinated operation of the first polarization unit and the first lens, thereby achieving local thermal modification of the surface material.

[0099] Optionally, such as Figure 3 As shown, the laser system 10 also includes a second polarization unit 16 and a second lens 17. The second polarization unit 16 is disposed in the optical path of the second laser beam R2 to apply the second laser beam R2 to the inner region L2. The second lens 17 is disposed between the second polarization unit 16 and the inner region L2.

[0100] For example, such as Figure 3 As shown, the second polarization unit 16 is disposed on the transmission optical path of the second laser beam R2 after it is split by the beam splitting unit 13, and is used to adjust the polarization state of the second laser beam R2. Similar to the first polarization unit 14, the second polarization unit 16 can be a polarizing optical element such as a polarizer, a half-wave plate, a quarter-wave plate, or a polarizing beam splitter prism.

[0101] Since the second laser beam R2 is incident on the side of wafer 30 into the internal region L2, its incident direction is different from that of the first laser beam R1 (perpendicular incident). Therefore, the polarization state response of the wafer material to the second laser beam R2 is also different. By adjusting the polarization state of the second laser beam R2 through the second polarization unit 16, the coupling efficiency and penetration depth of the second laser beam R2 on the side of wafer 30 and in the internal region L2 can be optimized, so that the gradient thermal modification process can achieve the expected energy deposition distribution.

[0102] The second lens 17 is disposed between the second polarization unit 16 and the inner region L2, and is used to focus the polarization-adjusted second laser beam R2 onto the inner region L2. For example, the second lens 17 can be an F-theta lens, which can focus the second laser beam R2 into a spot of a preset size and ensure that the second laser beam R2 is precisely focused and incident on the inner region L2 along the radial direction of the wafer 30. This application enables the second laser beam to be accurately applied from the side to the internal region of the wafer with optimized polarization and focusing by working in concert with the second polarization unit and the second lens, thereby achieving gradient thermal modification of the internal material.

[0103] According to one aspect of this application, a wafer edge processing method is provided.

[0104] According to the example embodiment, such as Figure 5 As shown, the wafer edge processing method includes steps S100-S300. This wafer edge processing method can be performed by the wafer edge processing apparatus described above.

[0105] In step S100, the wafer edge processing device applies a first laser beam to the surface region to perform local thermal modification on the surface region and form a first heat treatment layer.

[0106] For example, a laser system focuses a first laser beam and irradiates it perpendicularly onto the surface region of a wafer, locally heating and thermally modifying the surface material. This causes a structural change in the surface material, forming a first heat-treated layer. The hardness of this first heat-treated layer is reduced compared to the unmodified wafer material, thus forming a softening layer on the wafer edge surface.

[0107] In step S200, the wafer edge processing device applies a second laser beam to the inner region. The energy of the second laser beam is distributed in a gradient along the thickness direction of the wafer to perform gradient thermal modification treatment on the inner region, forming a second heat treatment layer. The first heat treatment layer and the second heat treatment layer form a composite modified region with a preset thermal gradient distribution. The hardness of the composite modified region changes in a gradient along the thickness direction of the wafer.

[0108] For example, a laser system directs a modulated second laser beam from the side of the wafer into the internal region, performing gradient thermal modification on the internal material to form a second heat-treated layer whose modification degree gradually varies along the thickness direction. The first and second heat-treated layers together form a composite modified region with a preset thermal gradient distribution. Along the thickness direction of the wafer, the hardness of this composite modified region gradually changes from the surface to the interior, without any abrupt hardness transitions, thus providing a pre-treatment structure with a gradual hardness transition for subsequent cutting.

[0109] In step S300, the wafer edge processing device cuts the composite modified region along the tangential direction of the wafer to remove the edge material of the composite modified region with the target thickness.

[0110] For example, the cutting assembly feeds radially along the wafer, bringing its outer edge into contact with the composite modification region. Due to the coordinated rotation of the wafer and the cutting assembly, the cutting assembly moves tangentially relative to the wafer edge, thus cutting the composite modification region along the wafer's tangential direction. Because the hardness of the composite modification region varies gradient along its thickness (lower surface hardness, higher internal hardness), the cutting resistance is low and stable when the cutting assembly enters from the surface. As the cutting depth gradually increases, the cutting resistance increases smoothly, resulting in a smooth transmission of cutting load and minimal fluctuation in cutting force throughout the cutting process. After cutting, the edge material of the composite modification region with the target thickness is completely removed, leaving a wafer edge profile with good consistency, high surface quality, and no chipping or microcracks.

[0111] It is understandable that the principle, process, and corresponding technical effects of dual-laser synergistic thermal treatment of the target edge region of the wafer by the laser system have been described in detail above, and will not be repeated here.

[0112] Using the wafer edge processing method described above, this application employs two laser beams with different functions to perform synergistic thermal modification of the wafer edge. The first laser beam locally thermally modifies the surface region of the wafer edge, causing local softening of the surface material and forming a first heat-treated layer with reduced hardness, thereby reducing the initial cutting resistance during subsequent trimming by the cutting assembly. The second laser beam applies a gradient energy density distribution to the internal region along the wafer thickness direction, enabling thermal gradient control and forming a gradient energy distribution within the internal region. The first and second heat-treated layers together form a composite modified region with a preset thermal gradient distribution. Along the wafer thickness direction, the hardness of this composite modified region gradually changes from the outside to the inside, forming a gradient modified layer structure that gradually transitions from a low-hardness softened area to a high-integrity unmodified area. The cutting assembly cuts the composite modified region along the wafer tangent direction, removing edge material of the target thickness, thus completing the wafer edge trimming process.

[0113] This application utilizes the synergistic effect of two laser beams to form a gradient modification layer with gradually changing hardness from the outside to the inside at the wafer edge. This effectively avoids problems such as local overheating, uneven thermal impact, and deep microcrack propagation that are prone to occur in traditional single-laser processing, thereby improving the stability and edge integrity of wafer edge trimming.

[0114] This application pre-constructs a gradient thermally modified region at the wafer edge, allowing the material hardness of the cutting component to gradually transition during the cutting process. This enables a smoother transmission of cutting loads, effectively mitigating localized stress concentration caused by material brittleness during mechanical trimming and reducing the risk of edge chipping and microcrack propagation. Simultaneously, the gradient thermally affected layer stabilizes the cutting state of the cutting component, reducing cutting force fluctuations and improving the consistency and surface quality of the wafer edge profile. Furthermore, since the composite modified region is limited to the area to be trimmed, it ensures improved wafer edge surface quality and profile accuracy while maintaining the integrity of the main wafer structure, thus enabling low-damage, high-precision wafer edge trimming. This application achieves synergistic control of wafer edge surface softening and internal gradient modification, significantly improving wafer edge trimming quality and processing stability.

[0115] Optionally, step S200 further includes: the wafer edge processing device adjusting the energy density of the second laser beam cross section so that the energy density of the second laser beam is gradient-distributed along the thickness direction of the wafer.

[0116] Optionally, step S200 further includes: the wafer edge processing device adjusting the transmittance of different regions of the second laser beam cross section to control the energy density of the second laser beam cross section.

[0117] Optionally, step S200 further includes: the wafer edge processing device performs energy differential attenuation on different regions of the second laser beam cross section to control the energy density distribution of the second laser beam cross section.

[0118] Optionally, the pulses of the first laser beam are output synchronously with the pulses of the second laser beam; or the pulses of the second laser beam have a first preset time interval relative to the pulses of the first laser beam; or the first laser beam and the second laser beam are output in an alternating pulse sequence, with a second preset time interval between adjacent pulses.

[0119] Optionally, the composite modification region includes a first modification segment and a second modification segment. The first modification segment extends from the surface layer of the composite modification region along the thickness direction of the wafer to a first depth, and the hardness of the first modification segment is the same along the thickness direction of the wafer. The second modification segment extends from the first depth along the thickness direction of the wafer to a second depth, and the hardness of the second modification segment varies in a gradient along the thickness direction of the wafer.

[0120] Optionally, the first depth accounts for 40% to 60% of the target thickness.

[0121] It is understandable that the principles, processing procedures, and corresponding achievable technical effects of the spatial light modulation unit's adjustment of the energy density distribution of the second laser beam (including transmittance adjustment and energy differential attenuation adjustment), and the pulse control of the first and second laser beams (including synchronous pulse output, delayed pulse output, and alternating pulse sequence output) have been described in detail above and will not be repeated here. Similarly, the structures, generation principles, and corresponding achievable technical effects of the first and second modification sections have been described in detail above and will not be repeated here.

[0122] Finally, it should be noted that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions of the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A wafer edge processing apparatus, characterized in that, include: A laser system performs dual-path laser-assisted thermal processing on a target edge region of a wafer, wherein the target edge region includes at least partially overlapping surface and internal regions. The laser system applies a first laser beam to the surface region to perform localized thermal modification on the surface region, forming a first heat-treated layer; Furthermore, the laser system applies a second laser beam to the internal region, the energy of the second laser beam being gradient-distributed along the thickness direction of the wafer, to perform gradient thermal modification treatment on the internal region, forming a second heat treatment layer, the first heat treatment layer and the second heat treatment layer forming a composite modified region with a preset thermal gradient distribution, and the hardness of the composite modified region changing gradient along the thickness direction of the wafer. A cutting assembly cuts the composite modified region along the tangent direction of the wafer to remove edge material of the composite modified region having a target thickness.

2. The wafer edge processing apparatus according to claim 1, characterized in that, The laser system includes: A spatial light modulation unit is disposed in the optical path of the second laser beam to adjust the energy density of the cross section of the second laser beam, so that the energy density of the second laser beam is distributed in a gradient along the thickness direction of the wafer.

3. The wafer edge processing apparatus according to claim 2, characterized in that, The spatial light modulation unit adjusts the transmittance of different regions of the second laser beam cross section to control the energy density of the second laser beam cross section.

4. The wafer edge processing apparatus according to claim 2, characterized in that, The spatial light modulation unit performs energy differential attenuation on different regions of the second laser beam cross section to control the energy density of the second laser beam cross section.

5. The wafer edge processing apparatus according to claim 1, characterized in that, The pulses of the first laser beam are output synchronously with the pulses of the second laser beam; or The pulses of the second laser beam have a first preset time interval relative to the pulses of the first laser beam; or The first laser beam and the second laser beam are output in an alternating pulse sequence, with a second preset time interval between adjacent pulses.

6. The wafer edge processing apparatus according to claim 1, characterized in that, The laser system includes: The light source emits a laser beam; The beam splitting unit splits the laser beam into the first laser beam and the second laser beam.

7. The wafer edge processing apparatus according to claim 6, characterized in that, The laser system also includes: A first polarization unit is disposed in the optical path of the first laser beam to apply the first laser beam to the surface region; A first lens is disposed between the first polarization unit and the surface region; A second polarization unit is disposed in the optical path of the second laser beam to apply the second laser beam to the internal region; The second lens is disposed between the second polarization unit and the internal region.

8. The wafer edge processing apparatus according to claim 1, characterized in that, The composite modified region includes: The first modified section extends from the surface layer of the composite modified region along the thickness direction of the wafer to a first depth, and the hardness of the first modified section is the same along the thickness direction of the wafer. The second modified section extends from the first depth along the thickness direction of the wafer to the second depth, and the hardness of the second modified section varies in a gradient along the thickness direction of the wafer.

9. The wafer edge processing apparatus according to claim 8, characterized in that, The first depth accounts for 40% to 60% of the target thickness.

10. A wafer edge processing method, characterized in that, The target edge region of the wafer includes at least partially overlapping surface and internal regions, and the wafer edge processing method includes: A first laser beam is applied to the surface region to perform localized thermal modification on the surface region, forming a first heat-treated layer; A second laser beam is applied to the internal region, the energy of which is gradient-distributed along the thickness direction of the wafer, to perform gradient thermal modification on the internal region, forming a second heat treatment layer. The first heat treatment layer and the second heat treatment layer form a composite modified region with a preset thermal gradient distribution. The hardness of the composite modified region varies gradient along the thickness direction of the wafer. The composite modified region is cut along the tangent direction of the wafer to remove the edge material of the composite modified region having a target thickness.

11. The wafer edge processing method according to claim 10, characterized in that, Applying a second laser beam to the internal region, wherein the energy of the second laser beam is gradient-distributed along the thickness direction of the wafer to perform gradient thermal modification treatment on the internal region includes: The energy density of the second laser beam cross section is adjusted so that the energy density of the second laser beam is gradient-distributed along the thickness direction of the wafer.

12. The wafer edge processing method according to claim 11, characterized in that, Adjusting the energy density of the second laser beam cross-section so that the energy density of the second laser beam exhibits a gradient distribution along the thickness direction of the wafer includes: The transmittance of different regions of the second laser beam cross section is adjusted to control the energy density of the second laser beam cross section.

13. The wafer edge processing method according to claim 11, characterized in that, Adjusting the energy density of the second laser beam cross-section so that the energy density of the second laser beam exhibits a gradient distribution along the thickness direction of the wafer includes: Differential energy attenuation is applied to different regions of the second laser beam cross-section to control the energy density distribution of the second laser beam cross-section.

14. The wafer edge processing method according to claim 11, characterized in that, The pulses of the first laser beam are output synchronously with the pulses of the second laser beam; or The pulses of the second laser beam have a first preset time interval relative to the pulses of the first laser beam; or The first laser beam and the second laser beam are output in an alternating pulse sequence, with a second preset time interval between adjacent pulses.

15. The wafer edge processing method according to claim 10, characterized in that, The composite modified region includes: The first modified section extends from the surface layer of the composite modified region along the thickness direction of the wafer to a first depth, and the hardness of the first modified section is the same along the thickness direction of the wafer. The second modified section extends from the first depth along the thickness direction of the wafer to the second depth, and the hardness of the second modified section varies in a gradient along the thickness direction of the wafer.

16. The wafer edge processing method according to claim 15, characterized in that, The first depth accounts for 40% to 60% of the target thickness.

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