A method and system for laser grooving of wafers

Abstract

This invention discloses a wafer laser grooving method and system, comprising: a laser beam being adapted to a spatial light modulator via optical path adjustment; the spatial light modulator loading a rectangular phase map to form a main light spot, with a high-frequency modulation pattern superimposed on the edge; the grooving width being adjusted by rotating the main light spot angle; a 4F system filtering the spectrum and reconstructing a composite light field containing the main light spot and two auxiliary sub-light spots; single-pulse staged operation, with the spatial light modulator synchronously controlling the light spot parameters; after focusing by the objective lens, the main light spot cuts the groove, and the auxiliary sub-light spots soften the edge. This invention solves the problems of poor edge quality and low efficiency of traditional methods, improving grooving accuracy, edge quality, and efficiency, and is suitable for high-precision wafer processing.

Description

Technical Field

[0001] This invention relates to the field of wafer dicing, and more particularly to a method and system for laser grooving of wafers. Background Technology

[0002] With the continuous development of semiconductor manufacturing technology, wafer dicing precision and edge integrity place higher demands on chip yield and packaging reliability. Traditional methods such as mechanical blade cutting, laser pyrolysis, and green laser cutting face a series of challenges in practical applications, such as high cutting stress, numerous edge microcracks, wide heat-affected zones, and difficulty in flexibly controlling the cutting path. Laser grooving technology, as a key process for processing precision devices such as wafers, essentially uses a laser beam to form grooves of specific dimensions on the material surface to meet the electrical isolation, heat dissipation, or packaging requirements of devices. As the semiconductor industry moves towards high density and miniaturization, the requirements for width accuracy, edge quality, and processing efficiency in wafer grooving are becoming increasingly stringent.

[0003] In recent years, pulsed laser cutting has gradually become an important method in the field of wafer grooving due to its non-contact, high precision, and low thermal impact. However, existing laser cutting technologies mainly use fixed spot morphology and single energy distribution, making it difficult to simultaneously control cutting depth and optimize edge quality. Especially when processing highly brittle materials such as silicon and gallium arsenide, defects such as microcracks and edge chipping are easily formed at the groove edges, which seriously affect device performance. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the problems of existing technologies, this application proposes a wafer laser grooving method and system, aiming to solve the problems of edge micro-cracks, edge chipping, and uncontrollable thermal effects in current laser cutting. This method introduces a spatial light modulator (SLM) to dynamically shape and frequency-domain control the laser beam field, achieving a composite configuration of a main beam and auxiliary sub-beams: the main beam, with high energy density, is used for core cutting, while the two lower-energy auxiliary sub-beams synchronously pre-soften the edges of the cutting path, significantly reducing material fracture stress and the risk of edge defects. The system employs coordinated control of polarization adjustment and SLM pattern loading, transforming the SLM spatial pattern into a frequency domain signal through a 4F system, and accurately filtering and restoring it to achieve high-quality imaging of the composite beam in the spatial domain. Furthermore, the laser pulse energy and the SLM modulation pattern are synchronized at the nanosecond level, synchronously switching the beam morphology and energy distribution at different stages of the laser pulse, ensuring optimal beam field matching in each stage of the cutting process—penetration, widening, and trimming. Finally, the composite light field is focused onto the wafer surface with high precision through the objective lens, which achieves high energy density cutting while ensuring that the edge material is in a softened state, reducing stress concentration, avoiding edge damage, and significantly improving the integrity of the cutting edge and the wafer yield.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution: a wafer laser grooving method, the cutting method comprising the following steps:

[0008] S1. Laser beam generation and optical path adaptation: The laser outputs pulsed laser, the transmission direction of the laser beam is adjusted by a mirror, the size of the light spot is adjusted by a beam expander, and the polarization direction of the laser is adjusted by a half-wave plate, so that the polarization direction is adapted to the sensitive characteristics of the spatial light modulator.

[0009] S2. Composite pattern loading: The spatial light modulator loads a preset shape to form the main light spot, and a periodic high-frequency modulation pattern is superimposed on the edge of the main light spot;

[0010] S3. Frequency Domain Filtering: The 4F system converts the composite light field output by the spatial light modulator to the frequency domain and retains the low-frequency spectrum corresponding to the main light spot and the high-frequency spectrum corresponding to the edge high-frequency modulation pattern through the filter aperture;

[0011] S4. Secondary imaging: The 4F system converts the filtered spectrum back to the spatial domain, forming a composite light field containing the main spot and auxiliary sub-spots symmetrically distributed on both sides of it;

[0012] S5. Timing-linked control: The single pulse output by the laser is divided into multiple energy stages. The spatial light modulator synchronously controls the shape, angle and energy distribution of the main spot and auxiliary sub-spots in each stage, so that the composite light field matches the pulse energy change.

[0013] S6. Focusing Grooving: The objective lens focuses the composite light field onto the wafer surface, the main light spot cuts the groove, and the auxiliary sub-light spot softens the groove edge simultaneously.

[0014] Preferably, in step S1, the reflector includes a first reflector and a second reflector. The first reflector changes the initial transmission direction of the laser beam, and the second reflector guides the laser beam, after being adjusted by the beam expander, to a half-wave plate.

[0015] Preferably, in step S2, the preset shape is a rectangle. By rotating the angle of the rectangular light spot, the slot width can be continuously adjusted within a preset range. The energy distribution of the light spot changes in a gradient, and the energy at the edge is lower than that at the center.

[0016] Preferably, in step S2, the periodic high-frequency modulation pattern is a sinusoidal wave structure with a frequency range of 50 to 150 line pairs / mm, used to form auxiliary sub-spots that are symmetrically distributed from left to right.

[0017] Preferably, in step S3, the 4F system consists of two convex lenses with the same focal length and a spacing of twice the focal length, forming a Fourier transform spectrum plane in the middle, and the filter stop is set on this spectrum plane.

[0018] Preferably, in step S3, the filter aperture includes a central low-pass filter region and an outer band-pass filter region. The central low-pass filter region is used to transmit the low-frequency spectrum of the main light spot, and the outer band-pass filter region is used to transmit the high-frequency spectrum of the edge high-frequency modulation pattern.

[0019] Preferably, in step S5, the plurality of energy stages include a pulse rising segment, a pulse stabilizing segment, and a pulse falling segment.

[0020] Preferably, in the pulse rising phase, the main spot adopts a sharp edge design to quickly penetrate the material; in the pulse steady phase, the width of the main spot is increased to widen the channel; and in the pulse falling phase, the edge of the main spot adopts an arc design to smooth the edge of the channel.

[0021] Preferably, in step S5, the energy and spacing of the auxiliary sub-spots are synchronously adjusted according to the parameter changes of the main spot at each energy stage. The energy density of the auxiliary sub-spots is 20%-40% of the energy density of the main spot.

[0022] A wafer laser grooving system based on the linkage of polarization adjustment and spatial light modulator includes a laser, a first mirror, a beam expander, a second mirror, a half-wave plate, a spatial light modulator, a 4F system, a third mirror, and an objective lens arranged in sequence.

[0023] The laser is positioned at the incident end of the first reflecting mirror and is used to output a laser beam;

[0024] The beam expander is mounted on the reflecting end of the first reflecting mirror and is used to adjust the size of the laser beam spot.

[0025] The beam expander has a second reflecting mirror at its light-emitting end; the second reflecting mirror has a half-wave plate at its reflecting end, which is used to change the polarization direction of the laser.

[0026] The spatial light modulator is placed at the light-emitting end of the half-wave plate to adjust the shape and energy distribution of the laser spot, and can change the slot width by rotating the spot angle.

[0027] The spatial light modulator is equipped with a 4F system at its output end, which is used to image the spatial light modulator and filter stray light in the laser.

[0028] The 4F system has a third reflecting mirror at the light-emitting end, and an objective lens at the reflecting end of the third reflecting mirror. The objective lens is used to focus the laser on the product surface so that the laser can create grooves on the product surface.

[0029] Furthermore, the spatial light modulator is connected to the laser via a synchronization signal line. The spatial light modulator receives the pulse trigger signal from the laser and switches the loaded phase pattern accordingly within a time of less than 100 ns.

[0030] (III) Beneficial Effects

[0031] The present invention aims to provide a wafer laser grooving method and system. By linking the spatial light modulator (SLM) with the laser output for control, a composite laser light field of "main spot + auxiliary sub-spot" is innovatively constructed. Combined with timing control and frequency domain filtering techniques, precise energy distribution and edge softening control are achieved during wafer dicing. Compared to traditional laser dicing methods, this invention effectively alleviates problems such as edge micro-cracks, chipping, and thermal damage that easily occur in brittle materials under laser irradiation while ensuring efficient dicing. The auxiliary sub-spot preheats and softens the edge material on both sides of the dicing path, reducing the stress of the edge material to a safe range. This reduces the stress of silicon material from 500MPa to 150MPa, significantly improving the integrity and smoothness of the diced edge, with roughness controllable below 0.3μm, and reducing the defect rate in subsequent cleaning and packaging processes. The entire system is non-contact, has low thermal impact, and allows for precise control of dicing width and depth, providing a high-yield, low-damage, and intelligently adjustable advanced laser dicing solution for high-end chip manufacturing, microelectronic packaging, and other fields. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the system architecture of the present invention;

[0033] Figure 2 This is a schematic diagram of the main light spot and auxiliary light spot of the present invention;

[0034] Figure 3 This is a schematic diagram of the slotting in Embodiment 1 of the present invention;

[0035] Figure 4 This is a schematic diagram of the slotting in Comparative Example 1 of the present invention.

[0036] In the diagram: 1-Laser, 2-First reflector, 3-Beam expander, 4-Second reflector, 5-Half-wave plate, 6-Spatial light modulator, 7-4F system, 8-Third reflector, 9-Objective lens. Detailed Implementation

[0037] The following will refer to the appendix in the examples of this invention. Figure 1 - Appendix Figure 4The technical solutions in the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0038] Example 1:

[0039] Processing target: Single crystal silicon wafer with a thickness of 500μm, with a target groove width of 83μm and a depth of 22μm.

[0040] This invention provides a technical solution: a wafer laser grooving method, the cutting method comprising the following steps:

[0041] S1 Laser Beam Generation and Optical Path Guidance

[0042] Laser startup and initial beam output: The laser is started according to preset parameters and outputs an initial laser beam.

[0043] The reflector adjusts the direction of the light path: the initial laser beam is transmitted in the horizontal direction. After being reflected by the first reflector, the direction of the light path turns vertically downward, ensuring that the laser is accurately aligned with the central optical axis of the subsequent optical components, and avoiding energy loss or spot distortion caused by optical path deviation.

[0044] The beam expander performs coarse adjustment of the spot size and energy matching, and selects the beam expansion factor according to the target width range: The beam expander consists of two sets of movable lenses, and the beam expansion factor can be switched from 1× to 3× by adjusting the lens spacing, so as to adjust the initial spot size to match the effective modulation area of ​​the spatial light modulator (SLM).

[0045] After the laser beam undergoes coarse adjustment by the beam expander, it enters the second reflector for a second optical path reversal. After reflection, the direction of the optical path is adjusted so that it changes from a vertical direction to a horizontal direction and is aligned with the incident end of the half-wave plate. The half-wave plate is a rotatable optical element. When the wave plate is rotated to a preset angle, the laser polarization direction is adjusted to the sensitive direction that matches the spatial light modulator.

[0046] S2 Composite Pattern Loading

[0047] S21 Basic Main Beam Modulation: The spatial light modulator (SLM) loads a preset rectangular phase diagram to shape the incident laser into a rectangular main beam, which is used for core cutting.

[0048] S22 Edge High-Frequency Modulation Superposition: On the left and right edges of the main spot, a periodic high-frequency modulation pattern is loaded by the SLM, specifically a sinusoidal wave with 100 line pairs / mm, i.e., the spacing between adjacent fringes is 10μm. The spatial frequency of this pattern is directly related to the target position of the auxiliary sub-spot: the higher the frequency, the denser the fringes, the farther the corresponding peak in the frequency domain is from the center, and the farther the final imaged sub-spot is from the main spot;

[0049] Modulation depth controls sub-spot energy: The amplitude of the stripes is set to 30% of the basic phase of the main spot to ensure that the energy of the auxiliary sub-spots formed subsequently is 30% of that of the main spot, so that they do not interfere with the cutting of the main spot and can effectively soften the edge.

[0050] The S3:4F system converts the spatial domain pattern to the frequency domain, completing the screening of high-frequency components.

[0051] The 4F system consists of two convex lenses, L1 and L2, each with a focal length of f and a spacing of 2f. The back focal plane of L1 coincides with the front focal plane of L2, forming a "Fourier transform plane," or spectral plane. Its core function is to transform the "spatial domain spot pattern" output by the SLM into a "frequency domain spectral distribution," and to filter out the key signals for forming auxiliary sub-spots using a filter aperture. The specific steps include:

[0052] Step 1: Fourier Transform

[0053] After passing through the spatial light modulator (SLM), the laser beam, carrying spatial information of "main spot + edge high-frequency modulation," first enters the first convex lens L1 of the 4F system. L1 converts the spatial spot pattern into a frequency spectrum distribution in the frequency domain.

[0054] The rectangular outline of the main light spot belongs to the "low frequency signal", which changes slowly in space. On the back focal plane of the frequency plane L1, it is manifested as a strong peak in the central region, with concentrated energy, corresponding to the basic energy of the main light spot.

[0055] The high-frequency modulation pattern at the edge, a sine wave with 100 line pairs / mm, belongs to the "high-frequency signal". In the spectrum, it is represented by two sub-peaks symmetrically distributed on both sides of the central peak. The radial distance of the sub-peaks from the center is proportional to the spatial frequency of the high-frequency signal: the higher the frequency, the farther the sub-peaks are from the center.

[0056] Step 2: Spectral surface filtering: used to filter auxiliary sub-spot signals.

[0057] A filter shutter is placed on the spectral plane, its structure matching the modulation signal of the SLM, retaining only the "low-frequency signal of the main spot" and the "high-frequency signal of the edge," while filtering out other stray light. This filter shutter includes:

[0058] Central low-pass filter area: It is a circular area with a diameter of 5mm and a transmittance of >90%. It allows the low-frequency spectrum of the main light spot to pass through, ensuring that the energy of the main light spot is fully preserved.

[0059] Two bandpass filter zones: These are located on the periphery of the central area, with two symmetrically arranged annular filter bands aligned with the second peak position of the high-frequency modulation pattern. The transmittance is 30%-40%, allowing only the 100 line pairs / mm high-frequency signal loaded by the spatial light modulator (SLM) to pass through.

[0060] S4: Secondary imaging, the 4F system reconstructs the main spot + auxiliary sub-spot in the spatial domain.

[0061] After being filtered by the spectral plane, the spectral signal enters the second convex lens L2 of the 4F system, completing the inverse conversion from the frequency domain to the spatial domain, and finally forming a composite light field at the back focal plane of L2, i.e., the entrance end of the objective lens.

[0062] The process of restoring the main light spot is as follows: the central low-frequency spectrum undergoes an L2 inverse Fourier transform, which restores it in the spatial domain to a rectangular main light spot of 83μm×22μm, maintaining an energy density of 1.2×10⁻⁶. 6 W / cm².

[0063] Formation of auxiliary sub-spots: The high-frequency spectra selected from both sides are subjected to L2 inverse Fourier transform to form two symmetrical spots in the spatial domain, namely auxiliary sub-spots:

[0064] Spatial location: Since the high-frequency spectrum is located on both sides of the center of the spectrum plane, after inverse transformation in the spatial domain, the auxiliary sub-spots are naturally distributed on the left and right sides of the main spot, 3-5 μm away from the edge of the main spot;

[0065] Energy characteristics: Since the transmittance of the bandpass filter area is 30%-40%, the energy of the auxiliary sub-spot is 30% of that of the main spot, which just reaches the material softening threshold. This avoids additional cutting and can soften the edges in advance.

[0066] S5: Timing linkage, the composite optical field enters the timing linkage stage, and the SLM and laser pulses are synchronized and controlled.

[0067] The composite optical field formed by the main beam and auxiliary sub-beams, after leaving the 4F system, enters a timing-synchronized stage with the laser pulse. The single pulse output from the laser, with a total pulse width of 50 ns, is divided into three energy stages. The SLM synchronously switches the beam parameters, ensuring precise matching between the effect of the composite optical field and the pulse energy changes.

[0068] (1) First stage: 0-15ns

[0069] Laser status: Pulse energy increases from 0 to 30% of peak value, energy density increases to 1.2 × 10⁻⁶. 6W / cm², rapidly penetrates the surface of materials.

[0070] SLM beam control:

[0071] The main beam spot remains an 83μm×22μm rectangle, but the edge slope is adjusted to <1μm, and the energy is concentrated in the center to ensure rapid material penetration with minimal energy.

[0072] The position of the auxiliary sub-spot remains unchanged, while the energy density increases synchronously to 3.6 × 10⁻⁶. 5 W / cm², which is 30% of the main light spot, pre-softens the edge material of the breakdown path, and raises the temperature to the softening point of silicon ≈1200K.

[0073] Effect: The main spot penetrates the wafer surface to create an initial channel with a depth of about 5μm, while the auxiliary sub-spot simultaneously softens the edge of the channel, preventing cracking due to stress concentration during penetration.

[0074] (2) Second stage: 15-35ns

[0075] Laser status: Pulse energy remains at 50% of peak value, and energy density is stable at 1.0 × 10⁻⁶. 6 W / cm², widening the channel to both sides.

[0076] SLM beam control:

[0077] Main spot: Width increased by 5%, approximately 23 μm, and edge slope increased to 2 μm, resulting in a smoother energy transition and an energy distribution that expands to both sides. The central energy drops to 80% of the peak value, while the edge energy increases to 50% of the peak value.

[0078] Auxiliary sub-spots: Widened synchronously with the main spot, with the spacing increasing from 4 μm to 5 μm, while maintaining an energy density of 3.6 × 10⁻⁶. 5 W / cm², continuing to soften the edges of the newly widened area.

[0079] The main spot expands to both sides based on the initial channel, with a total width of 80% of the target value and a depth of 60% of the target value. The auxiliary sub-spots simultaneously soften the new edge to avoid material tearing during the widening process, thus keeping the edge roughness below 0.5μm.

[0080] (3) Third stage: 35-50ns

[0081] Laser status: Pulse energy decreases from 50% of peak value to 20%, and energy density decreases to 6 × 10⁻⁶. 5 W / cm², suitable for low-energy edge trimming.

[0082] SLM beam control:

[0083] Main spot: The edge switching is an arc design with a radius of 10μm, and the energy distribution is "low in the middle and slightly higher at the edge". The edge energy is 60% of the main peak, avoiding secondary damage to the processed area by sharp edges;

[0084] Auxiliary sub-spot: Energy density is simultaneously reduced to 30% of the main spot, 2×10 5 W / cm², perform a second scan on the sidewall of the channel to smooth out burrs.

[0085] Effect: The arc-shaped edge of the main spot trims the sidewall of the channel, and the auxiliary sub-spot weakens the residual stress, ultimately reducing the edge roughness from 1.2μm to below 0.3μm.

[0086] S6: Grooving: The composite light field is focused by the objective lens and acts on the wafer surface.

[0087] After timing adjustment, the composite light field leaves the linkage between the SLM and the laser and enters the focusing range of the objective lens. The core function of the objective lens is to focus the composite light field onto the wafer surface, reducing the spot size to 1 / 10 of its original size, further increasing the energy density, and ultimately achieving the grooving:

[0088] The energy density of the main beam after focusing is increased to 1.2 × 10⁻⁶. 7 W / cm², instantly vaporizing the wafer material to form the main channel; then the focused auxiliary sub-spot energy density is 3.6×10 6 W / cm², applied 0.1μs in advance at the edge of the main beam cutting path, raises the material temperature to 1500K, achieving a softened but not vaporized state, reducing material brittleness; during main beam cutting, the edge material has already been softened by the auxiliary sub-beam, reducing stress from the traditional 500MPa to 150MPa, lower than the yield strength of silicon (270MPa), completely preventing cracking, and ultimately focusing to form the main body of the channel; the finished channel shape is as follows. Figure 3 As shown.

[0089] Comparative Example 1: Conventional grooving method

[0090] Processing object: Same as the single crystal silicon wafer in Example 1, with the same target parameters.

[0091] Equipment parameters: Laser is the same as in Example 1; optical system is conventional aperture shaping, fixed P polarization, without SLM and 4F system; objective lens is the same as in Example 1.

[0092] Specific steps: The laser beam output from the laser is shaped into a single rectangular spot by a fixed aperture, with an energy density of 1.5 × 10⁻⁶. 6 W / cm²;

[0093] Processing is performed in three consecutive pulses:

[0094] The first pulse, with an energy of 3mJ, penetrates the surface layer to a depth of 10μm.

[0095] The second pulse, with an energy of 4 mJ, widens the channel to a width of 50 μm.

[0096] Third pulse, energy 2mJ: trimming edges;

[0097] The groove shape after processing is as follows Figure 4 As shown.

[0098] Appendix Figure 3 The image shows the completed grooving process according to an embodiment of the present invention. It displays smooth and even groove edges with no obvious burrs or cracks, uniform groove width, and excellent overall processing quality. Figure 4 The image shown in Comparative Example 1 shows the completed grooving. It is evident that there are significant burrs at the edge of the groove, and multiple cracks appear. The cracked areas extend irregularly along the edge of the groove, with poor width consistency. The two attached images form a stark contrast, intuitively demonstrating the significant advantages of this invention in improving the quality of wafer grooving edges.

[0099] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for laser grooving of wafers, characterized in that, Includes the following steps: S1. Laser beam generation and optical path adaptation: The laser outputs pulsed laser, the transmission direction of the laser beam is adjusted by a mirror, the size of the light spot is adjusted by a beam expander, and the polarization direction of the laser is adjusted by a half-wave plate, so that the polarization direction is adapted to the sensitive characteristics of the spatial light modulator. S2. Composite pattern loading: The spatial light modulator loads a preset shape to form the main light spot, and a periodic high-frequency modulation pattern is superimposed on the edge of the main light spot; S3. Frequency Domain Filtering: The 4F system converts the composite light field output by the spatial light modulator to the frequency domain and retains the low-frequency spectrum corresponding to the main light spot and the high-frequency spectrum corresponding to the edge high-frequency modulation pattern through the filter aperture; S4. Secondary imaging: The 4F system converts the filtered spectrum back to the spatial domain, forming a composite light field containing the main spot and auxiliary sub-spots symmetrically distributed on both sides of it; S5. Timing-linked control: The single pulse output by the laser is divided into multiple energy stages. The spatial light modulator synchronously controls the shape, angle and energy distribution of the main spot and auxiliary sub-spots in each stage, so that the composite light field matches the pulse energy change. S6. Focused Grooving: The objective lens focuses the composite light field onto the wafer surface, the main light spot cuts the groove, and the auxiliary sub-light spot softens the groove edge simultaneously; In step S2, the preset shape of the main light spot is rectangular. By rotating the angle of the light spot, the slot width can be continuously adjusted within a preset range. The energy distribution of the light spot changes in a gradient, and the energy at the edge is lower than that at the center. In step S2, the periodic high-frequency modulation pattern is a sinusoidal wave structure with a frequency range of 50 to 150 line pairs / mm, used to form auxiliary sub-spots that are symmetrically distributed from left to right. In step S5, the multiple energy stages include a pulse rising phase, a pulse stabilizing phase, and a pulse falling phase; During the pulse rise phase, the main beam spot is designed with sharp edges to quickly penetrate the material; during the pulse steady phase, the main beam spot width is increased to widen the channel. During the pulse descent phase, the edge of the main spot is designed with an arc shape to smooth the edge of the channel; In step S5, the energy and spacing of the auxiliary sub-spots are synchronously adjusted at each energy stage as the parameters of the main spot change.

2. The wafer laser grooving method according to claim 1, characterized in that, In step S1, the reflector includes a first reflector and a second reflector. The first reflector changes the initial transmission direction of the laser beam, and the second reflector guides the laser beam, after being adjusted by the beam expander, to a half-wave plate.

3. The wafer laser grooving method according to claim 1, characterized in that, In step S3, the 4F system consists of two convex lenses with the same focal length and a spacing of twice the focal length, forming a Fourier transform spectrum plane in the middle, and the filter stop is set on this spectrum plane.

4. The wafer laser grooving method according to claim 3, characterized in that, In step S3, the filter aperture includes a central low-pass filter region and an outer band-pass filter region. The central low-pass filter region is used to transmit the low-frequency spectrum of the main light spot, and the outer band-pass filter region is used to transmit the high-frequency spectrum of the edge high-frequency modulation pattern.

5. The system for the wafer laser grooving method according to any one of claims 1-4, characterized in that, It includes a laser (1), a first reflector (2), a beam expander (3), a second reflector (4), a half-wave plate (5), a spatial light modulator (6), a 4F system (7), a third reflector (8), and an objective lens (9) arranged in sequence. The laser (1) is disposed at the incident end of the first reflector (2) and is used to output a laser beam; The beam expander (3) is mounted on the reflecting end of the first reflecting mirror (2) and is used to adjust the size of the laser beam spot. The beam expander (3) has a second reflector (4) at its light-emitting end; the second reflector (4) has a half-wave plate (5) at its reflecting end, which is used to change the polarization direction of the laser. The spatial light modulator (6) is placed at the light-emitting end of the half-wave plate (5) to adjust the shape and energy distribution of the laser spot, and can change the slot width by rotating the spot angle; The spatial light modulator (6) is equipped with a 4F system (7) at the light output end, which is used to image the spatial light modulator (6) and filter stray light in the laser. The 4F system (7) is provided with a third reflector (8) at the light-emitting end, and an objective lens (9) is provided at the reflecting end of the third reflector (8). The objective lens (9) is used to focus the laser on the product surface so that the laser can make grooves on the product surface.

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