Method and device for efficiently exfoliating diamond by super surface microlens array

Abstract

A method and device for efficiently peeling off diamond by using a metasurface microlens array, comprising the following steps: attaching a microlens array to the surface of the diamond to be peeled off, the microlens array being provided with a plurality of spherical cap micro-protrusions on the side away from the surface of the diamond, forming a micro-protrusion lens array; irradiating the microlens array with a low-energy laser beam, and forming a plurality of modified points in the diamond by the focusing effect of the spherical cap micro-protrusions on the microlens array; repeatedly irradiating the same area at intervals for multiple times until a uniform modified layer is formed; separating the microlens array from the surface of the diamond; focusing a high-energy laser beam on the modified layer for scanning, inducing the crack to propagate along the (111) crystal plane, and forming a peeling layer; and peeling off the diamond along the peeling layer by using ultrasonic or mechanical methods. The present application can efficiently and lowly damage peel off the diamond with a thickness of greater than or equal to 3 mm, has a fast processing speed, can be directly used for device manufacturing, and has a cost advantage.

Description

Technical Field

[0001] This invention relates to the field of diamond laser processing technology, and in particular to a method and apparatus for efficiently removing diamond using a metasurface microlens array. Background Technology

[0002] Diamond, as the hardest material in nature, possesses irreplaceable application value in high-end semiconductor devices, optical windows, quantum sensors, and power electronics due to its excellent thermal conductivity (>2000 W / m·K), superior broadband light transmittance (from ultraviolet to far-infrared), and extremely high chemical stability. With the rapid development of 5G communication, new energy vehicles, and quantum computing technologies, the demand for diamond-based devices is experiencing explosive growth. However, diamond's extreme hardness also makes it one of the most difficult materials to process, and traditional processing methods face enormous challenges: during mechanical cutting, diamond saw blades have extremely low cutting efficiency (typically only a few millimeters per hour), and the material loss rate is as high as 30%-50%. The process is also prone to crack propagation, leading to the entire wafer breaking apart; mechanical cleavage methods usually require pre-creating cracks and then applying mechanical stress to achieve cleavage propagation, which limits the cutting depth (usually <500μm), with an edge chipping rate as high as 20%, and the material utilization rate is less than 50%. Especially in the processing of large-size wafers (>2 inches), the uneven stress distribution leads to a sharp drop in yield; selective chemical etching uses the difference in etching rates between laser-modified and unmodified areas to achieve separation, but the etching speed is slow and the effect is poor. Molten salt treatment can lead to surface oxidation.

[0003] Laser lift-off (LLO) technology, as a potential solution to the challenges of diamond processing, achieves controlled separation of materials by inducing a modified layer within the material using a focused laser beam. The core principle of this technology utilizes the selective light absorption characteristics of diamond; when a high-energy-density laser is focused inside the diamond, it can induce spp in a localized area. 3 →sp 2 Phase transition (graphitization) forms a structurally weakened layer. By precisely controlling laser parameters (wavelength, energy, pulse width, etc.), the weakened layer forms continuous crack propagation, ultimately achieving clean material removal. However, existing laser ablation technology faces the following problems: (1) The working distance of traditional objectives is limited (usually <1mm), making it difficult to achieve deep internal modification of diamond substrates with a thickness >1mm; (2) The laser scanning efficiency is low, with conventional scanning speeds of only 0.1-1mm / s, which is difficult to meet the needs of industrial production; (3) The roughness of the ablation surface is poor, and subsequent polishing processes lead to additional material loss. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and apparatus for efficient and low-loss removal of diamond using a metasurface microlens array. This method and apparatus can be used in the processing and manufacturing of thick-bottomed diamond devices, providing technical support for the large-scale production of next-generation diamond-based semiconductor devices.

[0005] This invention is achieved through the following technical solution:

[0006] A method for efficiently removing diamond using a metasurface microlens array includes the following steps:

[0007] The microlens array is placed on the surface of the diamond to be peeled off, and the air between the microlens array and the diamond surface is expelled so that the microlens array is in close contact with the diamond surface. Several spherical crown-shaped micro-protrusions are provided on the side of the microlens array away from the diamond surface to form a micro-convex lens array.

[0008] The microlens array is irradiated with a low-energy laser beam. With the focusing effect of the spherical micro-protrusions on the microlens array, the low-energy laser beam forms a focal point array at a set depth in the diamond, which causes several modified particles to be formed inside the diamond. The same area is irradiated repeatedly at intervals until a uniform modified layer is formed inside the diamond.

[0009] The microlens array was separated from the diamond surface, and a high-energy laser beam was used to irradiate the diamond surface. The high-energy laser beam was focused on the modified layer for scanning, which induced cracks to propagate along the (111) crystal plane and form a peeling layer.

[0010] Diamonds are peeled off along the release layer using ultrasonic or mechanical methods.

[0011] Furthermore, the parameters for the high-energy laser beam irradiation are as follows: the high-energy laser is a continuous laser, the laser wavelength is 300-800 nm, and the power density is 0.5 × 10⁻⁶. 4 -5×10 4 W / cm 2 The scanning speed is 50-200 mm / s (driven by a linear motor), and the angle between the scanning direction and the crystal orientation is ≤15°.

[0012] Furthermore, the parameters of the low-energy laser beam irradiation are as follows: the low-energy laser is a nanosecond laser with a pulse width of 10-30 ps, ​​a wavelength of 400-1200 nm, and a single pulse energy of 0.2-1.0 J / cm². 2 (below the diamond damage threshold of 1.2 J / cm) 2 The low-energy laser beam is repeatedly irradiated in the same area 3-5 times at intervals of 5-15 ms.

[0013] Furthermore, the diameter of the spherical microprotrusions on the microlens array is 1.5-3 μm, the aspect ratio is 0.6-0.8 (spherical), and the array spacing of the spherical microprotrusions is 2-20 μm (adjusted by an electrically controlled translation stage).

[0014] Furthermore, the microlens array is made of sapphire or quartz glass, and the fabrication of the microlens array includes the following steps: preparation of photoresist microlens master; reactive ion etching; ion beam polishing; and high-transparency film deposition.

[0015] Furthermore, the method for preparing the photoresist microlens master is as follows: after cleaning and drying a double-sided polished sapphire or fused silica substrate using a standard RCA cleaning process, photoresist is spin-coated onto the surface. The substrate is then exposed in a photolithography machine using a pre-designed chromium mask. After sufficient exposure and reaction, the photoresist in the exposed area is dissolved using a developer, leaving a photoresist pillar array on the substrate surface. The substrate is then heated at a certain temperature to above the glass transition temperature of the photoresist, causing the photoresist to melt and flow into a smooth spherical shape, forming the photoresist microlens array master.

[0016] Furthermore, the reactive ion etching method is as follows: a plasma reactive ion etching machine is used, the etching gas is a mixture of CHF3, CF4, Ar, and O2, and after etching, the residual photoresist or polymer residue is removed by cleaning; the parameters of the ion beam polishing are: the ion source is Ar + The physical sputtering energy of the ion beam is 300-800 eV, the incident angle is 45°±5° (to avoid shadowing effect), and the beam current density is 1-5 mA / cm². 2 .

[0017] Furthermore, the surface roughness Ra of the substrate after ion beam polishing is ≤0.1nm. The high-transparency film is deposited in the following three layers from the inside out: HfO2 film, SiO2 film and TiO2 film. The thicknesses of HfO2 film, SiO2 film and TiO2 film are 120nm, 80nm and 60nm respectively. The refractive index n of HfO2 film is 2.0, the refractive index n of SiO2 film is 1.48 and the refractive index n of TiO2 film is 2.4.

[0018] Furthermore, the method of placing the microlens array on the diamond surface to be peeled off, expelling the air between the microlens array and the diamond surface, and making the microlens array adhere tightly to the diamond surface includes the following steps:

[0019] Surface polishing: The surfaces of diamond and microlens arrays are polished using laser or chemical mechanical polishing methods to achieve a surface roughness Ra < 0.5 nm;

[0020] Surface cleaning: The following steps are included in sequence: (1) ultrasonic cleaning with organic solvents (acetone, isopropanol); (2) RCA standard cleaning: SPM removes organic matter, SC-1 removes organic contaminants and particles, and SC-2 removes metal ion contaminants; (3) ultrapure water rinsing; (4) high-purity nitrogen blowing or spin drying.

[0021] Surface activation treatment: The diamond surface is activated by plasma using an Ar / N2 mixed gas, and the sapphire or quartz glass surface is activated by plasma using pure O2. The activation power is controlled at 50-200W to avoid surface damage, and the time is 30-120s.

[0022] Heating bonding: After precisely aligning the two activated bonding surfaces, place them in a bonding machine. Apply pressure under vacuum and a specific temperature, and the activated atoms between the two surfaces form chemical bonds, completing the bonding process. The bonding temperature can be controlled at 100-200℃, the pressure at 2-20 MPa, and the bonding time at 20-60 minutes.

[0023] An apparatus for efficiently removing diamond using a metasurface microlens array, and a method for achieving the aforementioned efficient removal of diamond using a metasurface microlens array, comprising a microlens array, a low-energy laser processing module, a high-energy laser processing module, and a three-dimensional motion processing stage.

[0024] The microlens array is made of sapphire or quartz glass, with one side being a smooth plane with a roughness Ra < 0.5 nm, and the other side having several spherical micro-protrusions forming a micro-convex lens array.

[0025] The low-energy laser processing module includes a low-energy laser generator, a beam expander, and an acousto-optic modulator (AOM). The low-energy laser generator is used to generate low-energy lasers, the beam expander is used to increase the laser beam diameter and improve beam collimation, and the acousto-optic modulator is used to generate pulsed lasers with a set pulse width and repetition frequency. The laser beam generated by the low-energy laser generator passes sequentially through the beam expander, the acousto-optic modulator, and the microlens array to reach the diamond.

[0026] The high-energy laser processing module includes a high-energy laser generator and a galvanometer scanning system. The high-energy laser generator is used to generate high-energy lasers, and the galvanometer scanning system is used for rapid positioning of the laser beam. The laser beam generated by the high-energy laser generator passes through the galvanometer scanning system and the microlens array in sequence to reach the diamond.

[0027] The three-dimensional motion processing stage is used to drive the sample fixed on it to perform three-dimensional motion, so that the sample can be transferred between the low-energy laser processing module and the high-energy laser processing module, and the position of the sample can be adjusted for processing.

[0028] This invention utilizes the multi-point focusing characteristics of a microlens array and employs low-energy pulsed lasers to induce diamond sp. 3 →sp 2 Phase transformation forms a uniform modified layer inside the diamond, which, combined with high-energy-density laser beam scanning to induce directional crack propagation, completely modifies the diamond's interior, ultimately achieving efficient and low-damage diamond removal. A high-transmittance sapphire or quartz glass substrate microlens array is directly attached to the diamond surface, replacing the traditional objective lens at the focusing end. The defocused laser beam sequentially generates uniformly distributed damage points within the diamond. Compared to conventional focusing objectives, the working distance is approximately zero, overcoming the limitations of traditional objectives and enabling the processing of diamonds with a thickness ≥3mm. Low-energy laser... Multiple subthreshold irradiation induces a uniform sp² modified layer, avoiding thermal damage. Dual-laser synergistic ablation results in high processing speed, reducing the surface roughness to 0.21 μm and graphite residue to <5%, eliminating the need for secondary polishing. This allows for direct use in device manufacturing with a material loss rate ≤3% and reduced processing energy consumption, offering a cost advantage. A microlens array with set parameters can be obtained through a combination of photoresist etching, reactive ion etching, ion beam polishing, and high-transparency film deposition. The transmittance and damage threshold of the microlenses meet the requirements of industrial-grade laser processing, and the microlens array can be reused more than 100 times. This invention can meet the substrate requirements of high-power diamond chips and quantum devices, providing technical support for the mass production of 4-inch and larger diamond substrates and even other substrate materials, and is expected to promote the implementation of third-generation semiconductor technology. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of step one of the embodiments of the present invention.

[0030] Figure 2 This is a schematic diagram of step two in an embodiment of the present invention.

[0031] Figure 3 This is a schematic diagram of step three in an embodiment of the present invention.

[0032] Figure 4 This is a schematic diagram of the fabrication of the microlens array in an embodiment of the present invention, wherein (a), (b), (c), and (d) represent steps (a), (b), (c), and (d), respectively.

[0033] Figure 5 This is a schematic diagram of the microlens array in an embodiment of the present invention.

[0034] Figure 6 This is a cross-sectional view of the microlens array in an embodiment of the present invention.

[0035] Figure 7 This is a schematic diagram of the high-transmittance film on the microlens array in an embodiment of the present invention.

[0036] Figure reference numerals: 1-Diamond; 11-Modified particle; 12-Crack; 13-Lifting layer; 2-Microlens array; 21-Spherical micro-protrusion; 22-HfO2 film; 23-SiO2 film; 24-TiO2 film; 3-Low-energy laser beam; 4-High-energy laser beam; 5-Substrate; 6-Photoresist; 7-Ion beam; Detailed Implementation

[0037] A method for efficiently removing diamond using a metasurface microlens array includes the following steps:

[0038] Step 1, such as Figure 1 As shown, the microlens array 2 is placed on the surface of the diamond 1 to be peeled off, and the air between the microlens array 2 and the surface of the diamond 1 is expelled, so that the microlens array 2 is in close contact with the surface of the diamond 1. The microlens array 2 is made of sapphire or quartz glass. Several spherical micro-protrusions 21 are provided on the side of the microlens array 2 away from the diamond surface to form a micro-convex lens array.

[0039] Step Two, as follows Figure 2 As shown, a low-energy laser beam 3 is used to irradiate the microlens array 2. With the focusing effect of the spherical micro-protrusions 21 on the microlens array 2, the low-energy laser beam 3 forms a focal point array at a set depth in the diamond 1, so that a number of modified points 11 are formed inside the diamond. The same area is repeatedly irradiated at intervals until a uniform modified layer is formed inside the diamond.

[0040] Step 3, as follows Figure 3 As shown, the microlens array 2 is separated from the surface of diamond 1, and the surface of diamond 1 is irradiated with a high-energy laser beam. The high-energy laser beam is focused on the modified layer for scanning, inducing crack 12 to propagate along the (111) crystal plane and forming a peeling layer 13.

[0041] Step 4: Use ultrasonic or mechanical methods to peel off diamond 1 along the peeling layer 13.

[0042] Ultrasonic methods involve placing the diamond directly in an ultrasonic water bath for ultrasonic peeling. Mechanical methods can be used by attaching the upper and lower surfaces of the diamond to the application surfaces with adhesive, and then applying force in opposite directions to the two application surfaces to peel it off. Alternatively, a thin blade or metal probe can be inserted into the peeling layer and gently applied to peel it off.

[0043] This invention uses a microlens array to replace the traditional laser objective lens, directly masking the diamond surface. It achieves efficient and low-damage peeling of thick-substrate diamond by combining low-energy multiple induced phase transitions with high-energy scanning directional pyrolysis.

[0044] Traditional objectives have short working distances (typically <1mm), making it difficult to achieve deep-layer modification of thick diamond substrates (>1mm). This invention directly attaches a microlens array to the diamond surface and replaces the traditional objective with a defocused microlens array at the focusing end, reducing the working distance to approximately zero. This allows for controllable, uniform deep-layer modification of diamond. Multiple irradiations with low-energy lasers can induce spp in localized areas of the diamond through a cumulative effect. 3 Hybridized carbon bonds break and rearrange into sp bonds. 2 The hybrid layered graphite structure utilizes the multi-point focusing properties of a microlens array to form a uniform modified layer inside the diamond. This modified layer, under high-energy-density laser irradiation, continuously absorbs energy due to the increased absorption rate in the damaged area, leading to a larger local temperature gradient and inducing crack propagation along the (111) crystal plane, ultimately achieving efficient and low-damage exfoliation of the material. High-transmittance near-infrared beams can minimize the beam's influence on the diamond's vertical direction, while high-energy green light can damage the internally formed confinement layer.

[0045] The parameters for the low-energy laser beam 3 irradiation can be set as follows: the low-energy laser is a nanosecond laser, the pulse width is 10-30 ps, ​​the wavelength is 400-1200 nm, and the single pulse energy is 0.2-1.0 J / cm². 2 (below the diamond damage threshold of 1.2 J / cm) 2 ).

[0046] As one embodiment, the low-energy laser has a pulse width of 20 ps, ​​a wavelength of 1064 nm, and a single pulse energy of 0.5 J / cm². 2 The low-energy laser beam can be generated by a YAG nanosecond laser pulse laser. After being modulated by a beam expander and an acousto-optic modulator (AOM), the laser beam is focused inside the diamond through a microlens array.

[0047] In order to achieve sp 3 →sp 2 Phase transition is performed, and to avoid thermal damage, pulsed laser is used to irradiate the same area multiple times. The number of irradiations is based on the formation of a uniform modified layer. In some embodiments, the number of repeated irradiations is 3-5 times, with an interval of 5-15ms, such as 10ms. The thickness of the modified layer can be controlled at 40±5μm.

[0048] The purpose of high-energy laser is to induce directional crack propagation, causing the modified layer to further develop and dissociate into a loose structure, facilitating subsequent peeling. The parameters of the high-energy laser beam 4 can be set as follows: the high-energy laser is a continuous laser, the laser wavelength is 300-800 nm, and the power density is 0.5 × 10⁻⁶. 4 -5×10 4 W / cm 2The scanning speed was 50-200 mm / s, and the angle between the scanning direction and the crystal orientation was ≤15°. The high-energy laser was focused on the modified layer, and the local temperature gradient was greater than 500 K / μm, thereby inducing crack propagation along the (111) crystal plane. Experiments showed that the crack deflection rate was >30% when the angle was >20°.

[0049] As one embodiment, the high-energy laser has a wavelength of 532 nm and a power density of 1 × 10⁻⁶. 4 W / cm 2 The scanning speed is 100 mm / s (driven by a linear motor). Specifically, the laser generates a 532 nm continuous laser, which is then focused inside the diamond through a microlens array after passing through a galvanometer.

[0050] Microlens arrays (MLAs) are important micro-optical components widely used in optical sensing, laser optics, beam shaping, imaging, and displays. The mainstream fabrication methods for MLAs currently include photoresist hot-melt reflow, grayscale lithography, and femtosecond laser direct writing / two-photon polymerization. For mass production, a master mold replication method can also be used, where a high-precision negative master mold is first created, and then mass production is achieved through replication technology.

[0051] This invention uses a microlens array instead of a traditional objective lens to form multiple focal points, with each microlens acting as a focusing lens. As the key optical element for laser ablation in this invention, the microlens array needs to possess certain thermal stability. In terms of material, sapphire, quartz, or other optical glasses can be used, with sapphire and quartz being particularly preferred. Sapphire is a single crystal form of aluminum oxide (Al2O3), with a Mohs hardness of 9 (second only to diamond), a light transmission range covering 0.15-5.5μm (ultraviolet to mid-infrared band), and a melting point as high as 2053℃. These characteristics of high hardness, high melting point, high compressive strength, excellent thermal conductivity, and chemical inertness make it an ideal material for optical windows in extreme environments. Quartz optical glass is made from pure quartz crystals (silicon dioxide), with a Mohs hardness of 7. It has a low coefficient of thermal expansion, high temperature resistance (1100-1200℃), high chemical stability, and excellent electrical insulation. Its ultraviolet transmission wavelength extends to 0.2μm, making it suitable for lens applications in special environments.

[0052] Specifically, such as Figure 5 , Figure 6 The diameter D of the spherical micro-protrusions 21 on the microlens array 2 is 1.5-3μm and can be adjusted according to actual conditions. The aspect ratio (H / D) is 0.6-0.8 (spherical), and the array spacing L of the spherical micro-protrusions is 2-20μm.

[0053] For microlens arrays made of sapphire and quartz, in order to realize their lens function, stringent requirements must be met, such as high-precision curved surface structure of Φ1.5-3μm, atomic-level surface smoothness of Ra≤0.1nm, and high light transmittance. However, due to the high hardness, high melting point, and chemical inertness of sapphire and quartz, their micro- and nano-fabrication is extremely difficult. The aforementioned conventional microlens fabrication methods often suffer from problems such as being difficult to implement, slow processing speed, poor effect, and high cost. These problems are mainly manifested in the following ways: traditional mechanical polishing cannot achieve micron-level feature sizes; wet etching has poor anisotropy, and dry etching has too low a rate, making it difficult for these traditional etching techniques to meet the precision requirements; and traditional laser direct writing has a heat-affected zone, leading to surface recrystallization.

[0054] In some of these embodiments, the most advanced 3D printing technology currently available can be used to 3D print on quartz glass to obtain various 3D structures, including micro-convex mirror arrays.

[0055] In other embodiments, a combination of photoresist hot-melt reflow and reactive ion etching is used to fabricate the microlens array, such as... Figure 4 As shown, the main steps include: (a) preparation of photoresist microlens master; (b) reactive ion etching; (c) ion beam polishing; and (d) high-transparency film deposition. The following uses a quartz substrate as an example to explain each step in detail.

[0056] (a) Preparation of photoresist microlens master

[0057] Select a double-sided optically polished fused silica substrate 5. Laser polishing can be used. After removing organic, inorganic, and metal ion contaminants through a standard RCA cleaning process and drying, photoresist 6, such as AZ series photoresist, is spin-coated onto the surface of the quartz substrate using a spin coater or spin coater. Then, a chromium mask with a pre-designed pattern is exposed in a photolithography machine. After sufficient exposure and reaction, the photoresist in the exposed area is dissolved using a developer, leaving a cylindrical or columnar photoresist column array on the surface of the quartz substrate. The substrate is then heated to a temperature above the glass transition temperature of the photoresist, generally controlled within the range of 130-160°C, so that the photoresist melts and flows into a smooth spherical shape, forming the photoresist 6 microlens array master.

[0058] (b) Reactive ion etching

[0059] The main objective is to etch and replicate the formed photoresist 6 microlens array onto the quartz substrate 5. This can be achieved using an inductively coupled plasma reactive ion etching (ICP-RI) machine. The etching gas can be a mixture of CHF3, CF4, Ar, and O2, generating fluorine radicals that react with SiO2 in the quartz to produce volatile SiF4, thus achieving chemical etching. This forms a quartz micro-convex lens array on the quartz surface with the same shape as the original photoresist lens array but with its height scaled according to the selectivity ratio. Oxygen plasma ashing and wet cleaning are then used to remove any remaining photoresist or polymer residues after etching, followed by cleaning and drying.

[0060] The above-mentioned laser process was used to obtain a micro-protrusion array. The diameter of a single spherical micro-protrusion 21 is Φ1.5-3μm, the aspect ratio is 0.6-0.8 (spherical), and the array spacing is 2-20μm.

[0061] (c) Ion beam polishing

[0062] Ion beam polishing is a non-contact, ultra-precision surface processing technology that can achieve polishing accuracy down to the sub-nanometer (<1nm) or even atomic level. Ion beam polishing is applied to the resulting micro-protrusion array to ensure the surface roughness meets requirements, facilitating more uniform subsequent coating.

[0063] The parameters for ion beam polishing (IBE) can be set as follows: the ion source is Ar. + The physical sputtering energy of ion beam 7 is 300-800 eV, the incident angle is 45°±5° (to avoid shadowing effect), and the beam current density is 1-5 mA / cm². 2 .

[0064] As one implementation method, the ion source is Ar. + The physical sputtering energy of ion beam 7 is 500 eV, Ar + An ion beam is incident at a 45° angle onto the polished micro-convex surface, with a beam current density of 2 mA / cm². 2 Polishing rate ≈ 5 nm / min.

[0065] The surface roughness Ra of the micro-protrusions obtained by the above method is ≤0.1nm, and the radius of curvature deviation is <±2%.

[0066] (d) High-transparency film coating

[0067] Depositing a high-transmittance film on a microlens is to improve its laser resistance. The film can be deposited using vacuum deposition or physical-chemical vapor deposition.

[0068] The film layer of this invention is a three-layer film with a graded refractive index. The surface roughness Ra of the microlens array after ion beam polishing is ≤0.1 nm. On this surface, such as Figure 7Three layers are deposited sequentially from the inside out: HfO2 film 22, SiO2 film 23, and TiO2 film 24. The refractive index of the HfO2 film is n=2.0; the refractive index of the SiO2 film is n=1.48, which can reduce stress; and the refractive index of the TiO2 film is n=2.4, which can resist environmental corrosion. In a preferred embodiment, the thicknesses of the three HfO2 / SiO2 / TiO2 films are 120nm / 80nm / 60nm, respectively.

[0069] This yields a microlens coated with a high-transmittance film, exhibiting a transmittance ≥99% at 532 nm and a laser damage threshold ≥8 J / cm² at a wavelength of 1064 nm and a pulse width of 10 ns. 2 It meets the needs of industrial-grade high-power laser continuous processing.

[0070] To overcome the limitations of objective lens working distance and achieve deep surface modification, a microlens array needs to be tightly attached to the diamond surface. Simultaneously, air between the microlens array and the diamond surface must be expelled to prevent thermal expansion of the air from affecting the adhesion, ensuring the microlens array remains firmly bonded to the diamond surface. Conventional adhesive bonding can interfere with laser irradiation processing and is difficult to meet high-temperature requirements. In this embodiment, a bonding process is used to achieve a tight bond, followed by a corresponding debonding process for separation. The bonding process mainly includes surface polishing, cleaning, surface activation, and thermal bonding steps, which are described in detail below:

[0071] Surface polishing: The surfaces of diamond and microlens arrays are polished using laser or chemical mechanical polishing methods. For diamond surfaces, laser polishing can be used; for sapphire or quartz glass surfaces, laser or chemical mechanical polishing methods can be used to achieve a surface roughness Ra < 0.5 nm.

[0072] Surface cleaning: mainly to remove debris, organic matter and other residues from the surface. In one embodiment, the cleaning mainly includes the following steps: (1) ultrasonic cleaning with organic solvents (acetone, isopropanol); (2) RCA standard cleaning: including SPM cleaning, RCA-1 cleaning and RCA-2 cleaning in sequence. SPM (H2SO4+H2O2) removes organic matter, SC-1 (H2O+H2O2+NH4OH) removes organic pollutants and particles, and SC-2 (H2O+H2O2+HCl) removes metal ion pollutants; (3) rinsing with ultrapure water with a resistivity of up to 18.2 MΩ·cm; (4) drying with high-purity nitrogen or spin drying.

[0073] Surface activation treatment: This mainly involves generating active groups on the bonding surface. In one embodiment, an Ar / N2 mixed gas is used to perform plasma activation on the diamond surface, and pure O2 is used to perform plasma activation on the sapphire or quartz glass surface. The activation power is controlled between 50-200W to avoid surface damage, and the activation time is 30-120s.

[0074] Thermal bonding: The purpose is to form strong covalent bonds between the activated surfaces, achieving bonding. Bonding can be performed in a bonding machine. After precisely aligning the two activated bonding surfaces, pressure is applied in a vacuum environment and at a specific temperature. The activated atoms between the two surfaces form chemical bonds, completing the bonding. The bonding temperature can be controlled at 100-200℃, the pressure at 2-20 MPa, and the bonding time at 20-60 minutes. For the bonding between diamond and sapphire, the main process is the formation of CO-Al covalent bonds.

[0075] In one embodiment of diamond-sapphire bonding, the activated surfaces of the diamond and sapphire are aligned and placed in a bonding machine. The bonding temperature is set to 150°C, the bonding pressure to 10 MPa, the bonding time to 60 min, and the vacuum degree to <1×10⁻⁶. -3 Pa, to avoid oxidation and bubble formation. The resulting bonding interface has a light transmittance of >99% and a thermal stress of 38 MPa.

[0076] For bonded microlens arrays, when separation is required in step three, appropriate unbonding methods can be used. To avoid damage caused by mechanical methods such as prying with blades, thermal stress methods can be used, which utilize the difference in thermal expansion / contraction to generate stress and cause them to separate. One side (such as sapphire) can be heated while the other side is not heated.

[0077] An apparatus for efficiently removing diamond using a metasurface microlens array, and a method for achieving the aforementioned efficient removal of diamond using a metasurface microlens array, comprising a microlens array, a low-energy laser processing module, a high-energy laser processing module, and a three-dimensional motion processing stage.

[0078] The microlens array is made of sapphire or quartz glass, with one side being a smooth plane with a roughness Ra < 0.5 nm, and the other side having several spherical micro-protrusions forming a micro-convex lens array.

[0079] The low-energy laser processing module includes a low-energy laser generator, a beam expander, and an acousto-optic modulator (AOM). The low-energy laser generator is used to generate low-energy lasers, the beam expander is used to increase the laser beam diameter and improve beam collimation, and the acousto-optic modulator is used to generate pulsed lasers with a set pulse width and repetition frequency. The laser beam generated by the low-energy laser generator passes sequentially through the beam expander, the acousto-optic modulator, and the microlens array to reach the diamond.

[0080] The high-energy laser processing module includes a high-energy laser generator and a galvanometer scanning system. The high-energy laser generator is used to generate high-energy lasers, and the galvanometer scanning system is used for rapid positioning of the laser beam. The laser beam generated by the high-energy laser generator passes through the galvanometer scanning system and the microlens array in sequence to reach the diamond.

[0081] The three-dimensional motion processing stage is used to drive the sample fixed on it to perform three-dimensional motion, transferring the sample between the low-energy laser processing module and the high-energy laser processing module, and adjusting the position of the sample for processing. The three-dimensional motion processing stage is equipped with a three-dimensional drive structure, which can be constructed from an X-axis linear motion module, a Y-axis linear motion module, and a Z-axis linear motion module. These linear motion modules can adopt existing electric cylinder or pneumatic cylinder driven structures, which will not be described in detail here.

[0082] The technical solution of this invention can be used for laser lift-off processing of diamonds with a thickness of 3mm or more. The microlens array enables multi-point parallel processing, resulting in fast lift-off speed. Practical experience has shown that it can lift 10×10mm diamonds... 2 The process takes only 100 seconds, compared to more than 3 hours with traditional methods. The surface roughness Ra is 0.21±0.03μm, the graphite residue rate is <5%, the material loss rate is ≤3%, the microlens array can be reused more than 100 times, and the laser energy consumption is reduced by 90%. It has been verified that it is applicable to the peeling process of CVD single crystal (Type Ia / IIa) and polycrystalline diamond wafers, laying the foundation for the mass production of 4-inch wafers. It is expected to solve the processing bottleneck of diamond-based high-power chips and quantum sensor substrates, and promote the implementation of third-generation semiconductor technology.

[0083] The above detailed description is a specific description of feasible embodiments of the present invention. These embodiments are not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included in the patent scope of this case.

Claims

1. A method for high-efficiency exfoliation of diamond by metasurface microlens array, characterized in that, The method comprises the following steps: placing a microlens array on the surface of the diamond to be peeled, discharging air between the microlens array and the surface of the diamond, and making the microlens array tightly adhere to the surface of the diamond, wherein the microlens array is provided with a plurality of spherical cap micro-protrusions on the side away from the surface of the diamond, forming a micro-lens array; irradiating the microlens array with a low-energy laser beam, forming a focused point array in the diamond at a set depth by the focusing effect of the spherical cap micro-protrusions on the microlens array, and forming a plurality of modified points in the diamond, repeatedly irradiating the same area at intervals for multiple times until a uniform modified layer is formed in the diamond; separating the microlens array from the surface of the diamond, irradiating the surface of the diamond with a high-energy laser beam, and focusing the high-energy laser beam on the modified layer to scan, so as to induce the crack to propagate along the (111) crystal plane and form a peeling layer; peeling the diamond along the peeling layer by a mechanical method; The parameters of the high-energy laser beam irradiation are as follows: the high-energy laser is a continuous laser, the laser wavelength is 300-800nm, the power density is 0.5x10 4 -5x10 4 W / cm 2 , the scanning speed is 50-200mm / s, and the angle between the scanning direction and the crystal direction is ≤15°. The parameters of the low-energy laser beam irradiation are as follows: the low-energy laser is a nanosecond laser, the pulse width is 10-30 ps, the wavelength is 400-1200 nm, and the single pulse energy is 0.2-1.0 J / cm 2 The low-energy laser beam is repeatedly irradiated in the same area for 3-5 times with an interval of 5-15 ms. the diameter of the spherical cap micro-protrusion on the microlens array is 1.5-3 μm, the depth-width ratio is 0.6-0.8, and the array spacing of the spherical cap micro-protrusion is 2-20 μm.

2. The method of claim 1, wherein, The microlens array is made of sapphire or quartz glass, and the processing of the microlens array comprises the following steps: photoresist microlens master preparation, reactive ion etching, ion beam polishing, and high-transparency film plating.

3. The method of claim 2, wherein, The method for preparing the photoresist microlens master comprises the following steps: after a double-side polished sapphire or fused quartz substrate is cleaned and dried through a standard RCA cleaning process, photoresist is spin-coated on the surface, a chromium mask plate with a designed pattern is used for exposure in a photoetching machine, after sufficient exposure reaction, a developing solution is used to dissolve the photoresist in the exposed area, and a photoresist column array is left on the surface of the substrate; then the substrate is heated to above the glass transition temperature of the photoresist at a certain temperature, so that the photoresist melts and flows into a smooth spherical cap, forming a photoresist microlens array master.

4. The method of claim 2, wherein, The method for reactive ion etching comprises the following steps: using a plasma reactive ion etching machine, the etching gas is a mixed gas of CHF3, CF4, Ar and O2, and after etching, the remaining photoresist or polymer residues after etching are removed by cleaning; The parameters of the ion beam polishing are: the ion source is Ar + , the physical sputtering energy of the ion beam is 300-800 eV, the incident angle is 45°±5°, and the beam current density is 1-5 mA / cm 2 .

5. The method of claim 2, wherein the method is characterized by, the surface roughness Ra of the substrate after ion beam polishing is less than or equal to 0.1 nm, and the high-transparency film plating is sequentially plated with the following three layers from inside to outside: HfO2 film, SiO2 film and TiO2 film, the thicknesses of the HfO2 film, the SiO2 film and the TiO2 film are 120 nm, 80 nm and 60 nm respectively, the refractive index n of the HfO2 film is 2.0, the refractive index n of the SiO2 film is 1.48, and the refractive index n of the TiO2 film is 2.

4.

6. The method of claim 1, wherein, The method for placing the microlens array on the surface of the diamond to be peeled, discharging air between the microlens array and the surface of the diamond, and making the microlens array tightly adhere to the surface of the diamond comprises the following steps: surface polishing: polishing the surfaces of the diamond and the microlens array by laser or chemical mechanical polishing to make the surface roughness Ra less than 0.5 nm; Surface cleaning: sequentially including the following steps: organic solvent ultrasonic cleaning; RCA standard cleaning, sequentially including SPM cleaning, RCA-1 cleaning and RCA-2 cleaning; ultrapure water flushing; high-purity nitrogen blowing or centrifugal dryer; Surface activation treatment: using Ar / N2 mixed gas to activate the diamond surface by plasma, using pure O2 to activate the sapphire or quartz glass surface by plasma, the activation power is controlled at 50-200W, and the time is 30-120s; Heating bonding: after the activated two bonding surfaces are accurately aligned, they are placed in a bonding machine, and a pressure of 2-20Mpa is applied under vacuum environment and a temperature of 100-200℃ for 20-60min.

7. An apparatus for high-efficiency exfoliation of diamond by metasurface microlens array, for implementing the method for high-efficiency exfoliation of diamond by metasurface microlens array according to any one of claims 1 to 6, characterized in that, It comprises a microlens array, a low-energy laser processing module, a high-energy laser processing module and a three-dimensional motion processing table; The microlens array is made of sapphire or quartz glass, one side of which is a smooth plane with a roughness Ra<0.5nm, and the other side is provided with a plurality of spherical cap micro-protrusions, and the plurality of spherical cap micro-protrusions form a microlens array; The low-energy laser processing module comprises a low-energy laser generator, a beam expander and an acousto-optic modulator, the low-energy laser generator is used to generate low-energy laser, the beam expander is used to expand the diameter of the laser beam and improve the collimation of the beam, and the acousto-optic modulator is used to generate pulse laser with set pulse width and repetition frequency, the laser beam generated by the low-energy laser generator passes through the beam expander, the acousto-optic modulator and the microlens array in sequence to reach the diamond; The high-energy laser processing module comprises a high-energy laser generator and a galvanometer scanning system, the high-energy laser generator is used to generate high-energy laser, and the galvanometer scanning system is used for rapid positioning of the laser beam, and the laser beam generated by the high-energy laser generator passes through the galvanometer scanning system and the microlens array in sequence to reach the diamond; The three-dimensional motion processing table is used to drive the sample fixed thereon to move in three dimensions, so as to transfer the sample between the low-energy laser processing module and the high-energy laser processing module, and adjust the position of the sample for processing.

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