Multi-beam intelligent focusing laser stealth cutting device and method

Abstract

The present application relates to the technical field of laser processing, and particularly relates to a multi-beam intelligent focusing laser stealth cutting device and method. The multi-beam intelligent focusing laser stealth cutting device comprises a laser source, a beam splitting module, a focal point control module and a wafer scanning module; the beam splitting module comprises a beam expander, a mirror, a diffraction light splitting device and a collimator lens group; the laser source emits a light beam to the beam expander; the beam expander is located between the laser source and the mirror; the present application can realize simultaneous cutting of multiple rows and multiple layers through single scanning, without repeated positioning, which can greatly improve the wafer stealth cutting efficiency, and the cutting efficiency is several times higher than that of the traditional single-layer process. By using ultrafast laser + multi-beam, energy dispersion is enabled, and the influence of the heat affected zone on the wafer is reduced. The present application can adjust the positions of the laser focal points of different rows in real time, and is compatible with different material thicknesses and structures.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, and in particular to a multi-beam intelligent focusing laser stealth cutting device and method, which achieves efficient stealth cutting of multi-layer wafers by dynamically adjusting the focal height in real time, and is suitable for precision processing of semiconductors, brittle materials and multi-layer composite structures. Background Technology

[0002] As semiconductor manufacturing technology rapidly advances towards miniaturization and integration, wafer dicing processes face stringent requirements for higher precision, lower damage, and higher efficiency. Traditional mechanical blade dicing, due to its contact processing, is prone to microcracks, edge chipping, and debris contamination, making it difficult to meet the processing needs of third-generation semiconductor materials (such as silicon carbide and gallium nitride) and ultra-thin wafers. Laser stealth dicing technology, by focusing a laser beam to form a modified layer inside the material and combining it with subsequent wafer expansion, achieves non-contact dicing. Due to its advantages such as no dust, low thermal impact, and high precision, it is gradually becoming a key process in advanced packaging.

[0003] Traditional laser stealth cutting uses an ultrashort pulse laser and a high numerical aperture (NA) lens to focus the laser beam into the material, forming a localized modified layer in the focal region through multi-layer scanning. External stress is then applied to cause the material to fracture precisely along the modified layer, achieving a "damage-free" cutting effect. However, existing traditional single-beam stealth cutting requires repeated scanning and cutting, resulting in low processing efficiency and the inability to process multiple rows and layers of structures simultaneously.

[0004] On the other hand, the lack of intelligent control capabilities further limits the adaptability of existing equipment. Traditional systems rely on preset parameters and struggle to respond in real time to dynamic changes during processing (such as fluctuations in material absorptivity and focus drift), resulting in a narrow process window. Therefore, developing an intelligent laser stealth cutting device with multi-beam collaborative control, dynamic adaptive adjustment, and high-precision real-time monitoring has become a key direction for overcoming existing technological bottlenecks and meeting the needs of future semiconductor manufacturing. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-beam intelligent focusing laser stealth cutting device and method to solve the problem that existing laser stealth cutting technologies require multiple repeated cuts, resulting in low processing efficiency.

[0006] In view of the above problems, the technical solution of the present invention is as follows:

[0007] A multi-beam intelligent focusing laser stealth cutting device includes a laser source, a beam splitting module, a focus control module, and a wafer scanning module;

[0008] The laser source is an ultrafast pulsed laser with a wavelength range from ultraviolet to near-infrared; the beam quality M of the laser beam 2The laser power is less than 1.1; the laser pulse width is adjustable from 0-50W; the laser pulse width is 100fs-200ns; the laser frequency is 1-400kHz. The ultrafast pulse laser uses a picosecond / femtosecond laser.

[0009] The beam-splitting module includes a beam expander, a reflector, a diffraction beam splitter, and a collimating lens group. The laser source emits a beam that illuminates the beam expander. The beam expander is located between the laser source and the reflector. The reflector is positioned above the diffraction beam splitter at a 45° angle to the horizontal, reflecting the light emitted from the beam expander back to the diffraction beam splitter. The diffraction beam splitter splits the light into multiple beams, which then illuminate the collimating lens group. The collimating lens group is located below the diffraction beam splitter, collimating the beam, which is then incident on a focusing lens group. The focusing lens group is located below the collimating lens group and mounted on an intelligent adjustment mechanism, focusing the beam onto the wafer sample. The wafer scanning module is located at the bottom. The wafer sample is located between the wafer scanning module and the focusing lens group. The dual-frequency laser interferometer is located on one side of the wafer scanning module, at the same height as the wafer sample. A dichroic mirror is located between the collimating lens group and the focusing lens group, and the CMOS image sensor receives the beam from the dichroic mirror.

[0010] The focus control module includes a focusing lens group, a depth sensing unit, and an intelligent adjustment mechanism;

[0011] The depth sensing unit includes a dichroic mirror, a dual-frequency laser interferometer, and a CMOS image sensor with a frame rate of 1000fps.

[0012] The accuracy of the dual-frequency laser interferometer is ±0.1μm;

[0013] The intelligent adjustment mechanism includes a piezoelectric ceramic micro-displacement platform and an independent closed-loop actuator. The piezoelectric ceramic micro-displacement platform has a stroke of ±3mm and a resolution of 50nm; the independent closed-loop actuator has a bandwidth of 2kHz.

[0014] Furthermore, the wafer scanning module includes a high-speed three-dimensional moving platform and a vacuum chuck;

[0015] Furthermore, the output port of the ultrafast pulse laser faces the input port of the beam expander, and the reflector is used to reflect the expanded light onto the diffraction beam splitter.

[0016] Furthermore, the diffraction beam splitting device divides the reflected laser into an N×M matrix of multiple beams;

[0017] Furthermore, the matrix of multiple beams illuminates the collimating lens;

[0018] Furthermore, the focusing lens group focuses the multi-beam laser; the depth sensing unit automatically generates a focal height gradient distribution curve based on wafer surface topology scanning data; the intelligent adjustment mechanism adjusts the height of each row of independent focusing lens groups through a piezoelectric ceramic micro-displacement platform, so that the height of the focusing lenses in different rows increases progressively.

[0019] Furthermore, the vacuum chuck of the wafer motion module is on the XY high-speed displacement platform, and the XY high-speed displacement platform and the ultrafast pulse laser are controlled by a control device. The displacement speed of the XY high-speed displacement platform is 0-500 mm / s.

[0020] A multi-beam intelligent focusing laser stealth cutting method, using a multi-beam intelligent focusing laser stealth cutting device, includes the following steps:

[0021] Step 1, Pre-processing: The wafer is pre-processed to make it suitable for laser stealth dicing.

[0022] Step 2, Clamping and Positioning: Use a vacuum chuck to hold the wafer to be cut. The vacuum chuck is fixed on the XY high-speed displacement platform.

[0023] Step 3, Beam Splitting: After the laser beam emitted by the laser is expanded by a beam expander to increase its diameter, it is reflected by a mirror to a diffraction beam splitter. The beam splitter then divides the single-beam laser into a matrix array of multiple beams, which are then collimated by a collimating lens group. The pulse width, frequency, and power of the multiple beams can be determined by a software program.

[0024] Step 4, Intelligent Focus Control: Using a dual-frequency laser interferometer and a CMOS image sensor, the depth information of the focal region is acquired in real time. The optimal depth of focus is automatically calculated based on the material, and the pulse overlap rate is dynamically adjusted. A piezoelectric ceramic micro-displacement platform is used to adjust the height of different rows of focusing lens groups, ensuring that the focal depth position is the same in each row, with the focal depth position increasing progressively between different rows (e.g., first row < second row < third row). The interval between the focal depth positions can be set according to the wafer thickness.

[0025] Step 5, multi-layer cutting: The laser parameters and the XY high-speed displacement platform are controlled by the control device to move along the cutting path to form multiple rows of multi-layer modified layers inside the wafer.

[0026] With the above structure, the beneficial effects of the present invention are as follows:

[0027] 1. A single scan can achieve simultaneous cutting of multiple rows and layers without repeated positioning, which can greatly improve the efficiency of wafer stealth cutting, and the cutting efficiency is several times higher than that of traditional single-layer processes.

[0028] 2. By using ultrafast lasers and multiple beams to disperse energy, the impact of the heat-affected zone on the wafer is reduced.

[0029] 3. It can adjust the laser focus position of different rows in real time and is compatible with different material thicknesses and structures. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a multi-beam laser stealth wafer dicing device according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of a multi-beam laser stealth cutting method for high-efficiency modified wafers according to an embodiment of the present invention.

[0032] In the figure: 1. Laser source; 2. Beam expander; 3. Mirror; 4. Diffraction beam splitter; 5. Matrix multi-beam; 6. Collimating lens group; 7. Intelligent adjustment mechanism; 8. Focusing lens group; 9. Wafer sample; 10. Wafer scanning module; 11. Dual-frequency laser interferometer; 12. Modified particle; 13. Dichroic mirror; 14. CMOS image sensor. Detailed Implementation

[0033] The present invention will be systematically described and explained in detail below with reference to the accompanying drawings. It should be noted that the specific embodiments listed in this specification are merely representative examples of the present invention and do not constitute a limitation on the scope of application of the technical solution. Based on the embodiments disclosed in this patent, technical solutions implemented by those skilled in the art within the scope of conventional technical capabilities, as well as other embodiments obtained through reasonable deduction and equivalent substitution of these embodiments, all fall within the protection scope of the patent rights of this invention.

[0034] Example 1

[0035] like Figure 1As shown, this embodiment provides a multi-beam intelligent focusing laser stealth cutting device, including a laser source 1, a beam expander 2, a reflector 3, a diffraction beam splitter 4, a collimating lens group 6, an intelligent adjustment mechanism 7, a focusing lens group 8, a wafer scanning module 10, and a dual-frequency laser interferometer 11. The laser beam is emitted from the laser source 1, expanded by the beam expander 2, and reflected by the reflector 3 onto the diffraction beam splitter 4. The diffraction beam splitter 4 splits the single beam into multiple beams, obtaining an n×m matrix of multiple beams 5. The beams are then collimated by the collimating lens group 6. The collimated matrix of multiple beams 5 is then branched by a dichroic mirror 13; one branch enters the focusing lens group 8 for focusing, while the other branch is reflected to a CMOS image sensor 14. The focusing lens group 8 has a focal length of ΔZ and is mounted on the intelligent adjustment mechanism 7. The intelligent adjustment mechanism 7 can adjust the height of the focusing lens group 8; for example, the height of the first row of n focusing lens groups can be set to Z1, the second row of n focusing lens groups to Z2, and the third row of n focusing lens groups to Z3. Each row of beams is focused at a different focal depth inside the foundry wafer workpiece 9 placed in the wafer scanning module 10. The dual-frequency laser interferometer 11 and the CMOS image sensor 14 monitor the actual focal height of each row in real time.

[0036] Specifically, in this embodiment, the diffraction beam splitting device 4 divides the expanded laser beam into n×m matrix beams.

[0037] Specifically, in this embodiment, the intelligent adjustment mechanism 7 adjusts the height of each row of independent focusing lens groups through a piezoelectric ceramic micro-displacement platform, so that the focal point height of different rows of beams gradually increases; the piezoelectric ceramic micro-displacement platform has a stroke of ±3mm and a resolution of 50nm;

[0038] Specifically, in this embodiment, the wafer sample 9 is a ground-semi-insulating 4H-SiC wafer. The wafer scanning module 10 includes a vacuum chuck and an XY high-speed displacement platform. The XY high-speed displacement platform and the ultrafast pulse laser are controlled by a control device, and the displacement speed of the XY high-speed displacement platform is 0-500 mm / s.

[0039] Specifically, in this embodiment, the laser source 1 is used to provide a pulsed laser beam with a wavelength range from ultraviolet to near infrared, an adjustable laser power of 0-50W, a laser pulse width of 100fs-200ns, and a laser frequency of 1-400kHz.

[0040] Example 2

[0041] This embodiment provides a multi-beam intelligent focusing laser stealth cutting method, which utilizes a multi-beam intelligent focusing laser stealth cutting device and includes the following steps:

[0042] Step 1: Pre-process the wafer sample 9 to make it suitable for laser stealth cutting.

[0043] Step 2: Use a vacuum chuck to pick up the wafer to be cut. The vacuum chuck is fixed on the XY high-speed displacement platform.

[0044] Step 3: The laser emitted by laser source 1 is expanded in diameter by beam expander 2, then reflected by mirror 3 to diffraction beam splitter 4. The single-beam laser is split into a matrix of multiple beams 5 by beam splitter, and the multiple beams are collimated by collimating lens group 6. The pulse width, frequency, and power of the multiple beams can be determined by software program.

[0045] Step 4: Using a dual-frequency laser interferometer 11 and a CMOS image sensor 14, the depth information of the focal region is acquired in real time. The optimal focal depth is automatically calculated based on the material, and the pulse overlap rate is dynamically adjusted. The height of different rows of focusing lens groups is adjusted using a high-precision piezoelectric ceramic micro-displacement platform via an intelligent adjustment mechanism 7, ensuring that the focal depth position is the same for each row, with the focal depth position of different rows increasing progressively (e.g., first row < second row < third row). The focal depth interval can be set according to the wafer thickness.

[0046] Step 5: Control the laser parameters and the wafer scanning module 10 along the cutting path through the control device to form multiple rows and layers of modified material inside the wafer sample 9.

[0047] like Figure 2 As shown, through the above steps, n×m modified particles 12 can be formed in one step inside the wafer sample 9. This method greatly increases the wafer stealth dicing efficiency, thereby reducing the laser scanning time and the number of scans.

[0048] This specification has described in detail the specific embodiments and preferred embodiments of the present invention. It should be clarified that, based on the core design concept of this invention, any technical improvements or derivative solutions implemented by those skilled in the art within the existing technical framework through the application of conventional technical means (including but not limited to logical deduction, conventional experiments, and technical adaptation) are all considered to fall within the protection scope of this invention. The specific definition of the above-mentioned scope of protection is subject to the legal definition of the claims appended to this patent application, and is not construed as restrictive due to the specific description of the embodiments in the specification.

Claims

1. A multi-beam intelligent focusing laser stealth cutting device, characterized in that, It includes a laser source (1), a beam splitting module, a focus control module and a wafer scanning module (10); the focus control module includes a focusing lens group (8), a depth sensing unit and an intelligent adjustment mechanism (7); The beam splitting module includes a beam expander (2), a reflector (3), a diffraction beam splitter (4), and a collimating lens group (6); the laser source (1) emits a beam that illuminates the beam expander (2); the beam expander (2) is located between the laser source (1) and the reflector (3); the reflector (3) is located above the diffraction beam splitter (4) at an angle of 45° to the horizontal direction, and is used to reflect the light transmitted from the beam expander (2) to the diffraction beam splitter (4); the diffraction beam splitter (4) splits the light into multiple beams and then illuminates the collimating lens group (6); the collimating lens group (6) is located below the diffraction beam splitter (4) and collimates the beam, and the collimated beam is incident on the focusing lens group (8); the focusing lens group (8) is located below the collimating lens group (6). The beam is focused on the wafer sample (9) by the intelligent adjustment mechanism (7) below the wafer scanning module (6); the wafer scanning module (10) is located at the bottom; the wafer sample (9) is located between the wafer scanning module (10) and the focusing lens group (8); the depth sensing unit includes a dichroic mirror (13), a dual-frequency laser interferometer (11) and a CMOS image sensor (14); the intelligent adjustment mechanism (7) includes a piezoelectric ceramic micro-displacement platform and an independent closed-loop driver; the dual-frequency laser interferometer (11) is located on one side of the wafer scanning module (10) and is at the same height as the wafer sample (9); the dichroic mirror (13) is located between the collimating lens group (6) and the focusing lens group (8); the CMOS image sensor (14) receives the beam from the dichroic mirror (13); The diffraction beam splitter (4) splits the reflected laser into an N×M matrix multi-beam (5); the matrix multi-beam (5) illuminates the collimating mirror; The focusing lens group (8) focuses the multi-beam laser; the depth sensing unit automatically generates a focal height gradient distribution curve based on wafer surface topology scanning data; the intelligent adjustment mechanism (7) adjusts the height of each row of independent focusing lens groups (8) through a piezoelectric ceramic micro-displacement platform, so that the height of the focusing lenses in different rows increases step by step. The depth information of the focal area is acquired in real time by a dual-frequency laser interferometer (11) and a CMOS image sensor (14), and the optimal focal depth is automatically calculated based on the material, and the pulse overlap rate is dynamically adjusted.

2. The multi-beam intelligent focusing laser stealth cutting device as described in claim 1, characterized in that, The wafer scanning module (10) includes a high-speed three-dimensional moving platform and a vacuum chuck; the vacuum chuck is on the XY high-speed displacement platform, and the XY high-speed displacement platform and the ultrafast pulse laser are controlled by a control device, and the displacement speed of the XY high-speed displacement platform is 0-500mm / s.

3. The multi-beam intelligent focusing laser stealth cutting device as described in claim 1, characterized in that, The laser source (1) is an ultrafast pulsed laser with a wavelength range from ultraviolet to near-infrared; the beam quality M of the laser beam 2 Less than 1.1; laser power adjustable from 0-50W; laser pulse width 100fs-200ns; laser frequency 1-400kHz; ultrafast pulse laser uses picosecond / femtosecond laser.

4. The multi-beam intelligent focusing laser stealth cutting device as described in claim 3, characterized in that, The output port of the ultrafast pulse laser faces the input port of the beam expander (2), and the reflector (3) is used to reflect the expanded light onto the diffraction beam splitter (4).

5. The multi-beam intelligent focusing laser stealth cutting device as described in claim 1, characterized in that, The CMOS image sensor (14) has a frame rate of 1000fps; the dual-frequency laser interferometer (11) has an accuracy of ±0.1μm.

6. The multi-beam intelligent focusing laser stealth cutting device as described in claim 1, characterized in that, The piezoelectric ceramic micro-displacement platform has a stroke of ±3mm and a resolution of 50nm; the independent closed-loop driver has a bandwidth of 2kHz.

7. The cutting method of the multi-beam intelligent focusing laser stealth cutting device according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1, Pre-processing: The wafer is pre-processed to make it suitable for laser stealth dicing. Step 2, clamping and positioning: Use a vacuum chuck to pick up the wafer to be cut; the vacuum chuck is fixed on the XY high-speed displacement platform. Step 3, beam splitting: After the laser emitted by the laser is expanded by the beam expander (2) to increase the beam diameter, it is reflected by the reflector (3) to the diffraction beam splitter (4). The single beam laser is split into a matrix array of multiple beams by the beam splitter. The multiple beam lasers are collimated by the collimating lens group (6). The pulse width, frequency and power of the multiple beam lasers can be determined by the software program. Step 4, Intelligent focus control: The depth information of the focus area is obtained in real time through the dual-frequency laser interferometer (11) and CMOS image sensor (14), and the optimal focal depth is automatically calculated according to the material. The pulse overlap rate is dynamically adjusted. The height of different rows of focusing lens groups (8) is adjusted by using a piezoelectric ceramic micro-displacement platform so that the focal depth position of each row is the same and the focal depth position of different rows is deepened layer by layer. Step 5, multi-layer cutting: The laser parameters and the XY high-speed displacement platform are controlled by the control device to move along the cutting path to form multiple rows of multi-layer modified layers inside the wafer.

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