Method and device for modifying hard and brittle material through pulse laser

Abstract

The invention relates to a method and device for modifying a hard and brittle material through pulse laser. The method comprises the following steps that S1, a hard and brittle material crystal ingot is fixed to a three-dimensional moving platform; s2, a laser focus is focused at the position 0 higher than the bottom of the crystal ingot, the laser is controlled to conduct scanning on the same plane, and a continuous and uniform transverse modified layer is formed in the crystal ingot; s3, stripping the crystal ingot along the modified layer by applying an external force; s4, the focal point of the laser is moved upwards by the height, the thickness, obtained through actual measurement, of the surface metamorphic layer of the stripping face after interaction of the laser and the material in the previous stripping cycle is the thickness of the laser slice; and S5, repeating the scanning and stripping steps in the steps S2-S4 until layer-by-layer slicing of the crystal ingot is completed.

Description

Technical Field

[0001] This invention belongs to the field of precision machining technology, specifically referring to a laser slicing method for hard and brittle materials. Background Technology

[0002] Existing technology uses lasers to internally modify and slice hard and brittle material ingots. This technology focuses a high-energy laser beam into the interior of the hard and brittle material. During this process, laser-induced physicochemical changes alter the material properties of the laser-irradiated area, creating defects such as voids and cracks. Through continuous laser scanning, a large-area lateral modification region is formed at specific locations within the material, laying the foundation for subsequent wafer separation. Subsequently, external force or other forms of energy are used to achieve material separation. This method has been proven to be a novel and reliable solution for slicing hard and brittle material ingots. Because the entire process does not damage the crystal surface structure, it has advantages such as high efficiency, high precision, and minimal thermal damage, making it particularly suitable for slicing thin wafers of hard and brittle materials.

[0003] Existing technologies employing this method focus an ultrafast laser at a specific depth within a hard and brittle material, inducing the formation of a localized modified layer or microvoids. Subsequent external force is then applied to complete the peeling along a predetermined path. However, the laser-based internal modification slicing methods proposed in these patents utilize lasers that scan and modify the material layer by layer from top to bottom before peeling. After each layer is scanned and modified, external force or other forms of energy are used to separate the wafer along that modified layer. The laser focus then moves downwards to continue scanning and forming the next modified layer, repeating this cycle until the entire ingot is sliced. However, this method leaves a modified layer on the surface of the peeled ingot after each peeling, and the surface roughness is high, hindering the transmission of subsequent lasers. If internal modification peeling is to be performed again, the surface modified layer needs to be ground to remove it, preventing it from obstructing subsequent laser transmission for internal modification. Therefore, this method requires a subsequent grinding process, increasing processing and time costs. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for modifying hard and brittle materials using pulsed lasers, specifically employing the following technical solution: A method for modifying hard and brittle materials using pulsed lasers, comprising the following steps:

[0005] S1. Fix the hard and brittle material ingot onto the three-dimensional moving platform; S2. Focus the laser beam at a height above the bottom of the ingot. The laser is controlled to scan in the same plane to form a continuous and uniform transverse modification layer inside the ingot. S3. Apply external force to peel the crystal ingot along the modified layer; S4. Move the laser focus upwards by [height]. ,in , The thickness of the modified layer on the surface of the peeled surface is determined by actual measurement after the interaction between the laser and the material in the previous peeling cycle. The thickness d of the modified layer is measured in real time by an online optical coherence tomography (OCT) module (10) integrated into the processing optical path. The device of the present invention integrates an online OCT module, which can reconstruct a two-dimensional or three-dimensional microstructure profile of the sample in real time. The computer system (1) can automatically identify and calculate the average thickness d of the modified layer (such as microcrack region, amorphous region) on the peeled surface by analyzing the profile; the thickness δ of the laser slice is the preset target peeling thickness of a single wafer.

[0006] S5. Repeat the scanning and stripping steps in S2-S4 until the layer-by-layer slicing of the ingot is completed.

[0007] Preferably, the distance between the material to be processed and the laser focus is set by adjusting the height of the objective lens before processing, so that the laser focus is set above the bottom of the material to be processed. The place, the place The distance between the laser focus and the bottom of the ingot is used during the first laser modification. Set as wafer target peel thickness .

[0008] Preferably, in step S2, the laser focus is shaped into a flat focus along the lateral direction by an adaptive optical element, thereby modifying the material along the lateral direction and ultimately forming a continuous lateral modification layer inside the material.

[0009] Preferably, the external force applied in S3 is any one of mechanical force, thermal stress, acoustic energy, or electrochemical energy.

[0010] Preferably, the hard and brittle material of S1 is one of diamond, silicon carbide, silicon, glass, fused silica, gallium nitride, gallium oxide, sapphire, aluminum nitride, yttrium aluminum garnet, and spinel.

[0011] An apparatus for modifying hard and brittle materials using pulsed lasers, employing the method described above, includes a computer system, a laser, a beam expander, an adaptive optics element, a mirror, and a three-dimensional moving platform for fixing and moving the hard and brittle material ingot; wherein the computer system controls the movement of the laser and the three-dimensional moving platform; the laser emitted from the laser is beam-shaped by the beam expander and the adaptive optics element, and after being reflected by the mirror, it is focused onto the laser lateral modification region of the hard and brittle material ingot.

[0012] This invention offers the following advantages: First, a pulsed laser is used to perform a transverse scan starting from a specific height above the bottom of a hard, brittle material ingot. After each layer of modification is completed, external force or other forms of energy are used to separate the wafer along that modified layer. Then, the laser focus moves upward, and the scan continues to form the next modified layer. This process is repeated to achieve layer-by-layer peeling of the entire ingot. Compared to current pulsed laser internal modification methods, this method uses a bottom-up laser modification direction. The laser penetrates the surface of the hard, brittle material and focuses at a specific height above the bottom of the ingot, forming a continuous transverse modified layer within a specially designed plane. The upper surface of the ingot remains undamaged, so subsequent internal modification does not affect the transmission of the laser. Currently, after internal modification and peeling using pulsed lasers, the modified layer still needs to be removed by grinding. Therefore, this method significantly improves the efficiency of laser modification and peeling. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the device for modifying hard and brittle materials using pulsed lasers according to the present invention.

[0015] Figure 2 This is a schematic diagram of the stripping of the ingot modification zone in this invention.

[0016] In the figure: 1-Computer system, 2-Laser, 3-Beam expander, 4-Adaptive optics element, 5-Mirror, 6-Objective lens, 7-3D moving platform, 8-Hard and brittle material ingot, 9-Laser lateral modification zone, 10-Online detection module for modified layer thickness. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example The following are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the following embodiments. All technical solutions that fall within the scope of the present invention are within the scope of protection of the present invention.

[0019] Reference manual attached Figure 1-2 A method for modifying hard and brittle materials using pulsed laser, characterized by comprising the following steps: S1. Fix the hard and brittle material ingot onto the three-dimensional moving platform; S2. Focus the laser beam at a height above the bottom of the ingot. The laser is controlled to scan in the same plane to form a continuous and uniform transverse modification layer inside the ingot. S3. Apply external force to peel the crystal ingot along the modified layer; S4. Move the laser focus upwards by [height]. ,in , The thickness of the modified layer on the surface of the peeled surface is determined by actual measurement after the interaction between the laser and the material in the previous peeling cycle. The thickness d of the laser slice is the target thickness of the wafer. The thickness d of the altered layer is obtained in real time by an online optical coherence tomography (OCT) module 10 integrated into the processing optical path. The device of this invention integrates an online OCT module, which can reconstruct a two-dimensional or three-dimensional microstructure cross-sectional image of the sample's interior in real time. The computer system 1 analyzes this cross-sectional image to automatically identify and calculate the average thickness d of the altered layer (such as microcrack regions or amorphous regions) on the peeled surface; the laser slice thickness δ is the preset target peeling thickness of a single wafer. S5. Repeat the scanning and stripping steps in S2-S4 until the layer-by-layer slicing of the ingot is completed.

[0020] A bottom-up internal modification method using pulsed lasers for hard and brittle materials involves fixing a hard and brittle material ingot on a three-dimensional moving platform. A pulsed laser is focused at a specific height above the bottom of the ingot. By controlling the laser's movement direction, a uniform transverse modification layer is formed within a specific plane. Then, a wafer is peeled off along the modification layer using any one of mechanical force, thermal stress, acoustic energy, or electrochemical energy. After wafer peeling, an ultrafast laser is controlled to move vertically from bottom to top, and the above operation is repeated to achieve the slicing process of the ingot. Figure 2 As shown.

[0021] The control system is a computer system, and the speed and direction of the three-dimensional moving platform can be precisely controlled by the computer system.

[0022] The hard and brittle material possesses properties such as high hardness and high brittleness; and it can be penetrated by lasers of corresponding wavelengths, achieving internal modification via ultrafast lasers. The hard and brittle material includes one of the following: diamond, silicon carbide, silicon, glass, fused silica, gallium nitride, gallium oxide, sapphire, aluminum nitride, yttrium aluminum garnet, and spinel.

[0023] The laser has a pulse width of 300 fs to 10 ps, ​​a wavelength of 1030 nm, and a repetition frequency of 25 kHz to 5 MHz. In this specific example, the laser repetition frequency is set to 25 kHz, the single-pulse energy to 3 µJ, the pulse width to 10 ps, ​​the scanning speed to 1500 mm / s, and a 20× (NA=0.4) objective lens is used. Before processing, the distance between the material to be processed and the laser focus can be adjusted by raising or lowering the objective lens. For example, in this example, the laser focus can be set approximately 100 µm above the bottom of the material to be processed.

[0024] The above description is merely a preferred embodiment of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention by those skilled in the art within the scope of the technology disclosed in the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A method for modifying hard and brittle materials using pulsed laser, characterized in that, Includes the following steps: S1. Fix the hard and brittle material ingot onto the three-dimensional moving platform; S2. Focus the laser beam at a height above the bottom of the ingot. At position 0, the laser is controlled to scan on the same plane to form a continuous and uniform transverse modification layer inside the ingot; S3. Apply external force to peel the crystal ingot along the modified layer; S4. Move the laser focus upwards by [height]. ,in , The thickness of the modified layer on the surface of the peeled surface is determined by actual measurement after the interaction between the laser and the material in the previous peeling cycle. The thickness of the laser slice; the thickness of the metamorphic layer The measurements were obtained in real time through an online optical coherence tomography module integrated into the processing optical path. S5. Repeat the scanning and stripping steps in S2-S4 until the layer-by-layer slicing of the ingot is completed.

2. The method for modifying hard and brittle materials using pulsed lasers according to claim 1, characterized in that, Before processing, the distance between the material to be processed and the laser focus is adjusted by raising and lowering the objective lens, and the laser focus is set above the bottom of the material to be processed. The place, the place The distance between the laser focus and the bottom of the ingot is used during the first laser modification. Set the target wafer stripping thickness δ.

3. The method for modifying hard and brittle materials using pulsed lasers according to claim 1, characterized in that, In S2, the laser focus is shaped into a flat focus along the lateral direction by an adaptive optical element, thereby modifying the material along the lateral direction and ultimately forming a continuous lateral modification layer inside the material.

4. The method for modifying hard and brittle materials by pulsed laser according to claim 1, characterized in that, The external force applied in S3 is any one of mechanical force, thermal stress, acoustic energy, or electrochemical energy.

5. The method for modifying hard and brittle materials by pulsed laser according to claim 1, characterized in that, The hard and brittle material of S1 is one of diamond, silicon carbide, silicon, glass, fused silica, gallium nitride, gallium oxide, sapphire, aluminum nitride, yttrium aluminum garnet, and spinel.

6. A device for modifying hard and brittle materials using pulsed laser, characterized in that, The method for modifying hard and brittle materials using pulsed laser as described in any one of claims 1-5 includes a computer system, a laser, a beam expander, an adaptive optics element, a reflector, a three-dimensional moving platform for fixing and moving the hard and brittle material ingot, and an online optical coherence tomography (OCT) module; wherein the computer system controls the movement of the laser and the three-dimensional moving platform; the laser emitted from the laser is beam-shaped by the beam expander and the adaptive optics element and then reflected by the reflector and focused into the laser transverse modification zone within the hard and brittle material ingot; the online OCT module is capable of reconstructing a two-dimensional or three-dimensional microstructure profile of the sample in real time; and the computer system automatically identifies and calculates the average thickness of the surface metamorphic layer by analyzing the profile.

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