Diamond laser slicing method and apparatus

Abstract

A method and apparatus for laser slicing diamond, the method comprising the following steps: 1) A laser beam is incident perpendicularly into the interior of a single-crystal diamond from the <100> plane, causing the CC bonds to break and carbonize to form graphite by creating instantaneous local high temperature; 2) The laser beam is scanned at a certain depth from the <100> plane and along the crystal direction, and by controlling the position of the laser focal plane and the energy at that position, only modified particles and graphite layers are formed, or modified particles and cracks extending along the <111> plane are formed, thereby forming a crack propagation layer, which generates a stress difference between the crack propagation layer and the unmodified layer, facilitating the peeling of the diamond layer.

Description

[Technical Field]

[0001] This invention relates to the field of diamond processing technology, and in particular to a method and apparatus for diamond laser slicing. [Previous Technology]

[0002] Diamond, as the hardest material in nature, is widely used in optical components, electronic devices, and aerospace fields due to its excellent physical properties, including extremely high hardness, thermal conductivity, and chemical corrosion resistance. Previously, silicon carbide (SiC) and gallium nitride (GaN) were offered as semiconductor materials suitable for power components to replace silicon (Si). Compared with these semiconductor materials, diamond semiconductors have a high dielectric breakdown electric field, a high power control index, and the highest thermal conductivity, thus attracting attention as a next-generation material and are being researched and developed towards practical application. However, due to the extremely high hardness and brittleness of diamond, traditional mechanical cutting methods easily lead to diamond breakage during processing, and the processing efficiency is low with high losses. Therefore, laser processing technology has become an effective alternative method for cutting diamond.

[0003] Existing traditional diamond slicing methods include laser ablation and ion implantation. Among them, laser ablation removes material through surface ablation, which has high processing efficiency, but has the problems of large cutting edge loss and unsuitability for large sizes; ion implantation has the problems of low processing efficiency, small processing area, and complicated steps.

[0004] Chinese invention patent application (publication number: CN115555743A, publication date: 2023-01-03) discloses a method for manufacturing a diamond substrate, comprising: a step of configuring a laser focusing part for focusing laser light to face the upper surface of a single-crystal diamond block; irradiating a laser from the laser focusing part toward the upper surface of the block, focusing the laser light into the interior of the block, while moving the laser focusing part relative to the block in a two-dimensional manner, thereby forming a modified layer comprising graphite processing marks and cracks extending around the (111) plane of the single-crystal diamond from the upper surface to a predetermined depth in a portion of the upper surface of the block; and a step of causing the cracks to spontaneously propagate to form a cracked surface from the modified layer to the predetermined depth in the remaining area of ​​the upper surface of the block.

[0005] As shown in Figures 1-3, the cleavage plane of single-crystal diamond is the <111> plane. In patent CN115555743A, the surface of the diamond sample is the <111> plane. Cracks are formed by scanning along the <111> plane, and the crack propagation direction is the <111> crystal orientation, perpendicular to the laser irradiation direction. In actual samples, due to the diamond crystal growth process, most single-crystal diamonds have the <100> crystal orientation as their upper surface. If damage points are formed and cracks are generated, the cracks will propagate along the <111> plane. At this point, the cracks are not easily connected, and a large damage layer is generated. The damage layer from the modified particles and cracks needs to be removed during subsequent grinding; therefore, a smaller damage layer is required to reduce laser loss. The laser loss mainly concerns the projection of the modified particles and cracks onto the <111> plane. [Summary of the Invention]

[0006] In order to solve the above-mentioned technical problems, the present invention provides a diamond laser slicing method based on laser modified particle generation and crack control, which can accurately control the arrangement of modified particles and / or crack propagation, optimize the stress distribution of the modified layer, thereby achieving high-precision diamond slicing and avoiding sample breakage and damage.

[0007] To achieve the above objectives, the present invention employs the following technical solution. A method for laser slicing diamond, comprising the following steps: 1) A laser beam is incident perpendicularly from the <100> plane into the interior of a single-crystal diamond, causing instantaneous local high temperature to break the C-C bonds and thus carbonize to form graphite; 2) The laser beam is scanned at a certain depth from the <100> plane and along the crystal direction, and by controlling the position of the laser focal plane and the energy at that position, only modified particles and graphite layer A are formed, or modified particles and cracks extending along the <111> plane are formed, thereby forming a crack propagation layer B, which generates stress difference and / or forms cracks between the modified layer and the unmodified layer, facilitating the peeling of the single-crystal diamond.

[0008] Preferably, by controlling the center distance L1 between adjacent modified points on the same beam path and the distance L2 between adjacent beam paths, the damage during laser processing is minimized, the stress distribution of the modified layer is uniform, and the amount of single crystal diamond removed is reduced.

[0009] Preferably, when the laser forms modified particles in the single-crystal diamond without producing cracks, the value of the distance L1 between the centers of adjacent modified particles and the distance L2 between the beam path is less than or equal to the diameter D1 of the modified particles along the <011> crystal direction, so as to ensure the connection between adjacent modified particles, form a dense graphite layer A, and avoid the generation of sample cracks or fragments.

[0010] Preferably, when the laser simultaneously forms modified particles and cracks in the single-crystal diamond, the center distance L1 between adjacent modified particles is less than or equal to the crack propagation length L3, and the distance L2 between the beam paths is less than or equal to half the diameter D2 of the modified particles, thereby forming a crack propagation layer B through the intersection of the graphite particles and the cracks.

[0011] As a further preferred option, the stress difference between the crack propagation layer B and the unmodified layer ensures that the internal stress of the crack propagation layer B is uniform, so that the peeling device can effectively peel off the single crystal diamond without generating fragments.

[0012] Furthermore, the present invention also discloses a diamond laser slicing device using the method described above. The device includes a laser module, an optical module, a clamping module, and a displacement module. The laser module generates a laser beam, the optical module focuses the laser beam inside the sample, the clamping module is used to fix the single crystal diamond, and the displacement module has XYZ three-dimensional motion capability to control the relative position of the sample and the depth of the laser focal plane.

[0013] Preferably, the displacement module controls the focusing depth of the laser inside the single crystal diamond through the Z-axis, and controls the planar movement of the sample through the X and Y axes, so as to realize the scanning of the laser beam along the crystal orientation or other preset directions.

[0014] Preferably, by adjusting the spacing L1 between adjacent modified points on the beam path and the distance L2 between adjacent beam paths, uniform slicing of single-crystal diamond by laser is achieved, reducing damage and optimizing the stress distribution of the modified layer.

[0015] Preferably, the optical module includes an adjustable focusing device that can instantly adjust the laser focal plane according to the thickness and crystal orientation of the single crystal diamond.

[0016] Preferably, the laser parameters generated by the laser module can be dynamically adjusted according to processing requirements to ensure that modified particles or cracks are generated at different slice depths, and to control the diameter of the modified particles and the length of the cracks.

[0017] By employing the above-mentioned technical solution, the present invention can significantly improve the precision and efficiency of diamond slicing and effectively reduce material damage. Its main technical effects include the following points.

[0018] 1. Improved cutting precision: By controlling the laser focusing depth and the energy of the laser beam, this invention can precisely generate modified particles and cracks inside diamond. Depending on actual needs, localized graphitization regions or cracks can be formed inside single-crystal diamond, thereby achieving high-precision material removal during the cutting process, resulting in a smooth slice surface with minimal error.

[0019] 2. Reduced material loss and thermal damage: This invention optimizes the arrangement of modified particles to ensure uniform distribution of stress in the graphite layer generated during laser processing, avoiding crack propagation caused by excessive thermal stress in traditional laser cutting. Especially after forming a dense graphite layer, the stress difference between the graphite layer and the unmodified area is used for peeling, significantly reducing material loss and thermal damage, ensuring a smooth, fragment-free cut surface.

[0020] 3. Improve slicing efficiency: Through the synergistic effect of the laser module, optical module, clamping module and displacement module in the laser device of the present invention, rapid and stable laser scanning can be achieved, the generation of the particle and the range of crack expansion can be precisely controlled, the degree of automation in the cutting process can be effectively improved, and thus the processing efficiency can be greatly improved.

[0021] 4. Improved Slicing Quality: Regarding the control of modified particles and crack propagation, this invention achieves the generation of a uniform and dense graphite layer A and a crack propagation layer B by adjusting the center distance L1 between adjacent modified particles and the distance L2 between adjacent beam paths, thus avoiding quality problems such as cracks and fragments caused by uneven stress. The uniform stress distribution in the modified layer ensures stable stress release during the slicing process, reducing grinding and finishing work in subsequent cutting steps.

[0022] 5. Controllable crack propagation: In the process of laser generation of modified particles, the present invention can precisely control the generation and propagation of cracks. By reasonably adjusting parameters such as distance L1, distance L2, diameter D1, and diameter D2, the cracks can be extended only within a preset range, avoiding excessive crack propagation that affects the slice quality, thereby ensuring that the cutting results meet the requirements of precision machining.

[0023] 6. Wide applicability: This invention is applicable to the processing of single crystal diamond slices of various sizes and thicknesses, and is especially suitable for high-end application scenarios with extremely high requirements for cutting accuracy and surface quality, further expanding the application field of diamond laser slicing technology.

[0024] In summary, the present invention, through precise control of modified particles and cracks in the laser slicing process, not only improves cutting accuracy and reduces material loss, but also significantly improves slicing efficiency and slice quality, providing an efficient and stable solution for the high-end diamond processing field.

Implementation Method

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making progressive efforts are within the protection scope of the present invention.

[0027] Example 1: The case where lasers generate modified particles inside diamond but do not produce cracks.

[0028] In this embodiment, the laser is incident perpendicularly into the interior of the single-crystal diamond through a surface. By utilizing precisely controlled laser energy and focusing depth, the laser creates localized high temperatures within the diamond, thereby inducing the breakage of C / C bonds and generating modified particles. At this time, the control of laser energy and its focal position ensures that modified particles are formed only within the diamond, without generating cracks.

[0029] 1. Setting laser parameters: Select appropriate laser power, pulse duration, and focusing depth to ensure that laser energy is concentrated at a specific location inside the diamond. The laser focus is adjusted to a certain depth Z1 inside the diamond. At this depth, the laser forms modified particles inside the single-crystal diamond.

[0030] 2. Formation and Control of Modified Particles: As shown in Figure 4, the laser raises the local temperature inside the diamond to a level sufficient to break the C-C bonds, but the controlled energy limits the thermal diffusion range, forming only modified particles without causing cracks. The diameter of the modified particles along the <011> crystal orientation is D1. By controlling the center distance L1 between adjacent modified particles and the distance L2 between adjacent beam paths, the modified particles are ensured to be uniformly distributed, forming a dense graphite layer A.

[0031] 3. Spacing between modified particles and formation of graphite layer A: The center distance L1 between adjacent modified particles on the same path is less than or equal to the diameter D1 of the modified particle, expressed by the following relationship: L1=L2≤D1; ensuring that adjacent modified particles intersect to form a sufficiently dense graphite layer A. The stress is uniformly distributed inside the graphite layer A, which allows the diamond layer to be successfully peeled off in subsequent peeling operations without causing cracks or fragments.

[0032] 4. Laser Scanning Process: The laser beam scans at a certain depth from the <100> plane along the crystal direction. Light is emitted point-by-point along each beam path at a set interval L1, ensuring that the laser generates uniform modified points within the diamond. The interval L2 between adjacent beam paths ensures that the modified points are neatly arranged, ultimately forming a graphite layer A. Since no cracks are generated, this modified layer is peeled off only through the stress difference between the graphitized and unmodified regions.

[0033] The following will provide a detailed description of this embodiment through experiments.

[0034] Experimental Setup: Laser Power: By adjusting the laser power, the generation of modified particles is ensured without inducing cracks. Focal Plane Depth: The laser focal point is set at a depth Z1 inside the single-crystal diamond. Modified Particle Diameter: D1 is the diameter of the modified particle along the <100> crystal orientation, and L1 and L2 control the distance between adjacent modified particles.

[0035] Experiment number Laser power (W) The diameter of the modified particle, D1 (µm). The distance between the centers of the modified particles is L1 (µm). Beam path distance L2 (µm) Thickness of graphite layer A (µm) Slice surface smoothness (µm) Does it develop cracks? Peeling effect 1 5 7.0 6.5 6.5 12.5 ±4.5 no excellent 2 7 10.2 9.5 9.5 14.7 ±5.0 no excellent 3 10 15.4 15.4 15.4 21.3 ±5.6 no excellent 4 12 20.1 20.1 20.1 26.4 ±7.3 no good

[0036] Example 2: The case where lasers generate modified particles and cracks inside diamond.

[0037] In this embodiment, the laser is also incident perpendicularly into the interior of the single-crystal diamond. By adjusting the laser energy and focusing depth, the laser not only forms modified particles within the diamond but also induces the generation and propagation of cracks. The cracks propagate along the crystal direction and intersect with the modified particles to form a crack propagation layer B.

[0038] 1. Laser parameter settings: The laser energy is set high enough to break the CC bond and induce crack generation. The laser focus is adjusted to a certain depth Z2 inside the diamond. At this depth, the laser generates modified particles inside the single crystal diamond and produces cracks along the <111> plane. Let D1 be the diameter of the modified particle along the <011> crystal direction, D2 be the diameter of the modified particle along the <100> crystal direction, L1 be the distance between the centers of adjacent modified particles on the same beam path, L2 be the distance between adjacent beam paths, L3 be the crack propagation length of the modified particle along the crystal direction (Figure 5), and α be the angle between the crack formed along the cleavage plane and the plane (Figure 6).

[0039] 2. Formation of Modified Particles and Cracks: Laser treatment not only generates modified particles but also induces crack propagation along the <111> crystal orientation. The diameter of the modified particles is D1, and the range of crack propagation is controlled by the crack propagation length L3 of the modified particles. By adjusting the distance L1 between the centers of adjacent modified particles, making the distance L1 less than or equal to the crack propagation length L3, it is ensured that the cracks intersect and form a uniform crack propagation layer B.

[0040] 3. Control of the intersection between modified particles and cracks: The relationship between the distance L2 between adjacent beam paths on the laser beam path and the diameter D2 along the crystal direction is: 2*L2≤D2 / tan(α); because the cleavage plane is the <111> crystal direction, α=45°, at this time L2≤D2 / 2. The crack propagation direction extends along the crystal direction and intersects with adjacent modified particles, thereby forming a crack propagation layer B and preventing excessive crack propagation.

[0041] 4. Laser Scanning Process: The laser beam scans at a certain depth from the <100> plane along the crystal direction. The laser beam generates modified particles point by point inside the diamond, simultaneously inducing cracks. The modified particles and cracks intersect on the beam path. The interval L2 between adjacent laser scanning lines ensures that the cracks and modified particles are evenly distributed, ultimately forming a crack propagation layer B. The crack propagation layer B, through the interwoven structure of cracks, creates a stress difference between the crack propagation layer and the non-modified layer, effectively preventing the generation of diamond fragments.

[0042] In this embodiment, due to the interaction between the crack and the modified particles, efficient peeling can be achieved, and the stress distribution of the crack propagation layer B can be ensured to be uniform, effectively improving the slice quality and accuracy. The following is a detailed description of this embodiment through experiments.

[0043] Experimental Setup: Laser Power: Laser power is increased to generate cracks. Focal Plane Depth: The laser focal point is set at a depth Z2 inside the single-crystal diamond. Modification of Particles and Crack Control: D1, D2, L1, L2, and L3 are key parameters used to control crack propagation and intersection with modified particles.

[0044] Experiment number Laser power (W) The diameter of the modified particle, D1 (µm). Modify the particle diameter D2 (µm) The distance between the centers of the modified particles is L1 (µm). Beam path distance L2 (µm) Crack propagation length L3 (µm) Crack intersection Are there excessive cracks? Slice surface smoothness (µm) Peeling effect 1 15 20.5 45.3 13.5 25.0 25.4 Good intersection no ±6.6 excellent 2 18 22.5 52.4 16.5 30.0 27.6 Good intersection no ±6.2 excellent 3 20 23.6 57.7 26.6 30.0 30.5 Good intersection no ±7.3 good

[0045] As shown in Figure 7, a diamond laser slicing device of the present invention comprises a laser module 20, an optical module 30, a clamping module 60, and a displacement module 70; wherein: the laser module 20 generates laser with specific parameters, and the laser parameters generated by the laser module can be dynamically adjusted according to processing requirements to ensure the generation of modified particles or cracks at different slicing depths, and to control the diameter of the modified particles and the length of the cracks; the optical module 30 transmits the laser and focuses it at the objective lens 40, and the optical module includes an adjustable focusing device that can adjust the laser focal plane in real time according to the thickness and crystal orientation of the single crystal diamond; the clamping module 60 fixes the sample; the displacement module 70 has XYZ three-dimensional motion capability, the Z-axis can drive the sample to move up and down to adjust the focusing depth of the laser inside the sample, and the X and Y axes realize the relative motion between the sample and the laser. The X and Y axes control the planar motion of the sample to realize the scanning of the laser beam along the crystal orientation or other preset directions.

[0046] The surface of the ingot 50 is used as the upper surface for processing. Before processing, observe the modification points and cracks in the single-crystal diamond under specific focusing depth, energy and other parameters. For the modification points, observe and record the diameter D1 of the modification point along the <011> crystal direction and the diameter D2 of the modification point along the <100> crystal direction, and observe and record whether cracks are generated under these parameters and the crack propagation length L3 along the crystal direction.

[0047] As shown in Figure 8, during processing, the laser beam scans along a certain depth Z1 from the surface and along the crystal direction or crystal direction. The laser beam is emitted along the same path according to the point spacing L1, and the adjacent laser scanning lines are parallel to each other with a line spacing L2.

[0048] Adjust the spacing L1 between adjacent modified points on the beam path and the distance L2 between adjacent beam paths to achieve uniform slicing of single-crystal diamond by laser, reduce damage, and optimize the stress distribution of the modified layer. For cases where modified points are generated but cracks are not, the distance (spacing) L1 between the centers of adjacent modified points on the same beam path and the distance L2 between adjacent beam paths must be less than or equal to the diameter D1 of the modified point along the <011> crystal direction. For cases where modified points are generated and cracks are generated, the distance L1 between the centers of adjacent modified points on the same beam path must be less than or equal to the crack propagation length L3 along the crystal direction of the modified point, and the distance L2 between adjacent beam paths must be less than or equal to half the diameter D2 along the <100> crystal direction. Repeat the scanning process using the above method until all areas of the ingot turn gray-black to ensure uniform stress distribution in the modified layer of the sample, which is then ready for peeling.

[0049] The above is a description of embodiments of the present invention. Through the above description of the disclosed embodiments, those skilled in the art will be able to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein. [Simplified Explanation of the Diagram]

[0025] Figure 1 is a schematic diagram of the cleavage plane of single-crystal diamond. Figure 2 is a schematic diagram of the projection of modified particles and cracks on the <011> plane. Figure 3 is a schematic diagram of the projection of modified particles and cracks on the plane. Figure 4 is a schematic diagram of the projection of modified particles and cracks on the <011> plane or plane when laser generates modified particles inside diamond but does not generate cracks. Figure 5 is a schematic diagram of the projection of modified particles and cracks on the <011> plane when laser generates both modified particles and cracks inside diamond. Figure 6 is a schematic diagram of the projection of modified particles and cracks on the plane when laser generates both modified particles and cracks inside diamond. Figure 7 is a schematic diagram of the diamond laser slicing device of the present invention. Figure 8 is a schematic diagram of laser beam scanning. [Biomaterial Storage]

[0051] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A method for laser slicing diamond, comprising the following steps: 1) using a laser beam to be incident perpendicularly into the interior of a single-crystal diamond from the <100> plane, thereby creating instantaneous local high temperature to break the C-C bonds and carbonize them to form graphite; 2) the laser beam is scanned at a certain depth from the <100> plane and along or in the crystal direction, by controlling the position of the laser focal plane and the energy at that position, only modified particles and graphite layer (A) are formed, or modified particles and cracks extending along the <111> plane are formed, thereby forming a crack propagation layer (B), which generates stress difference and / or forms cracks between the modified layer and the unmodified layer, facilitating the peeling of the single-crystal diamond.

2. The diamond laser slicing method as claimed in claim 1, wherein the center distance (L1) between adjacent particles on the same beam path and the distance (L2) between adjacent beam paths are controlled.

3. The diamond laser slicing method as described in claim 2, wherein when the laser forms modified particles in the single-crystal diamond without producing cracks, the center distance (L1) between adjacent modified particles and the distance between the beam paths (L2) are less than or equal to the diameter (D1) of the modified particles along the <011> crystal direction, ensuring the connection between adjacent modified particles and forming a dense graphite layer (A).

4. The diamond laser slicing method as described in claim 2, wherein when the laser simultaneously forms modified particles and cracks in the single-crystal diamond, the center distance (L1) between adjacent modified particles is less than or equal to the crack propagation length (L3), and the distance between the beam paths (L2) is less than or equal to half the diameter of the modified particles (D2), thereby forming the crack propagation layer (B) through the intersection of the graphite particles and the cracks.

5. The diamond laser slicing method as described in claim 4, wherein the stress difference between the crack propagation layer (B) and the unmodified layer ensures uniform internal stress in the crack propagation layer (B), enabling the peeling device to effectively peel the single crystal diamond without producing fragments.

6. A diamond laser slicing apparatus employing the diamond laser slicing method as described in any one of claims 1-5, comprising: a laser module, an optical module, a clamping module, and a displacement module, wherein the laser module generates a laser beam, the optical module focuses the laser beam inside the sample, the clamping module is used to fix the single-crystal diamond, and the displacement module has XYZ three-dimensional motion capability to control the relative position of the sample and the depth of the laser focal plane.

7. The diamond laser slicing apparatus as claimed in claim 6, wherein the displacement module controls the focusing depth of the laser inside the single-crystal diamond via the Z-axis, and controls the planar movement of the sample via the X-axis and Y-axis, so as to realize the scanning of the laser beam along the crystal orientation or other preset directions.

8. The diamond laser slicing apparatus as claimed in claim 6, wherein uniform slicing of the single-crystal diamond is achieved by adjusting the spacing (L1) between adjacent particles on the beam path and the distance (L2) between adjacent beam paths.

9. The diamond laser slicing apparatus as claimed in claim 6, wherein the optical module includes an adjustable focusing device capable of real-time adjustment of the laser focal plane according to the thickness and crystal orientation of the single crystal diamond.

10. The diamond laser slicing apparatus as claimed in claim 6, wherein the laser parameters generated by the laser module can be dynamically adjusted according to processing requirements to ensure that modified particles or cracks are generated at different slicing depths, and to control the diameter of the modified particles and the length of the cracks.

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