Substrate structure, substrate surface treatment method and apparatus

Abstract

This invention discloses a substrate structure, a substrate surface treatment method, and an apparatus. The method includes: providing a transparent inorganic substrate with a surface roughness Ra of 0.1 μm to 20 μm; forming an energy absorption layer on at least the surface to be treated, the energy absorption layer completely covering the micro-protrusions and micro-pits on the surface to be treated, the energy absorption layer having an energy absorption coefficient greater than that of the substrate; irradiating the substrate with an ultrashort pulse laser to induce a phase explosion in the energy absorption layer and multiphoton absorption in the micro-protrusion region; and, under the combined effects of phase explosion and multiphoton absorption, the laser cold-cuts the micro-protrusions; wherein the wavelength λ of the ultrashort pulse laser is within the range of n * Ra / 10 to n * Ra, where n is the refractive index of the substrate. This invention utilizes the combined effects of phase explosion and multiphoton absorption to cold-cut the micro-protrusions with a laser, thereby removing the micro-protrusions from the surface to be treated without damaging the substrate structure.

Description

Technical Field

[0001] This application relates to the field of laser processing and surface engineering technology, specifically to a substrate structure, a substrate surface treatment method, and an apparatus. Background Technology

[0002] Transparent inorganic materials, such as fused silica, crystalline silica, and calcium fluoride, have wide applications in aerospace, microelectronics, high-power laser optical components, and microfluidic chips due to their excellent optical transmittance, high hardness, high temperature resistance, and chemical stability. However, the "hard and brittle" mechanical properties and wide-bandgap optical properties of these materials pose significant challenges to their high-precision manufacturing.

[0003] Traditional machining methods (such as grinding and polishing) are inefficient and difficult to fabricate microstructures; wet chemical etching has poor precision and causes serious environmental pollution. In recent years, laser processing technology has become a research hotspot due to its advantages such as non-contact processing and high flexibility. However, significant technical bottlenecks still exist when processing transparent materials, especially for surface treatment with micron- and submicron-level roughness. For example, laser processing can easily induce catastrophic brittle fracture along cleavage planes. Summary of the Invention

[0004] The substrate structure, substrate surface treatment method and apparatus provided by the present invention can process the transparent inorganic substrate in the substrate structure provided by the present invention and reduce the surface roughness of the transparent inorganic substrate.

[0005] To address the above problems, the present invention provides a substrate surface treatment method, comprising: A transparent inorganic substrate is provided, wherein the surface roughness Ra of the substrate to be treated is within the range of 0.1 μm to 20 μm; An energy absorption layer is formed at least on the surface to be treated of the substrate, the energy absorption layer completely covering the micro-protrusions and micro-pits on the surface to be treated of the substrate, and the energy absorption coefficient of the energy absorption layer is greater than the energy absorption coefficient of the substrate. The substrate is irradiated with an ultrashort pulse laser to induce a phase explosion in the energy absorption layer and multiphoton absorption in the micro-protrusion region of the surface to be treated. Under the action of the phase explosion and multiphoton absorption, the laser performs cold cutting on the micro-protrusion to peel off the micro-protrusion on the surface to be treated without damaging the substrate structure. The wavelength λ of the ultrashort pulse laser is within the range of n * Ra / 10 to n * Ra, where n is the refractive index of the substrate.

[0006] In some embodiments, after surface treatment, the roughness Ra of the substrate surface to be treated is within 1 nm to 10 nm.

[0007] In some embodiments, the pulse width τ of the laser prevents thermal ablation of the energy absorption layer.

[0008] In some embodiments, the laser is a femtosecond laser or a picosecond laser.

[0009] In some embodiments, the power density of the laser ≈ Threshold light intensity at which the substrate material undergoes multiphoton absorption .

[0010] In some embodiments, the power density of the laser Light intensity less than the threshold for multiphoton absorption by the substrate material Furthermore, the laser beam irradiating the micro-protrusion is focused by the micro-protrusion, resulting in enhanced light intensity that reaches the threshold light intensity. .

[0011] In some embodiments, the energy absorption layer is a single-layer structure or a multi-layer structure.

[0012] In some embodiments, the energy absorption layer is a single-layer structure, and the thickness l of the energy absorption layer is equal to the light absorption ratio b of the energy absorption layer and the light absorption rate α of the energy absorption layer material.

[0013] In some embodiments, the energy absorption layer is a multilayer structure, where α1×l1+α2×l2......+αn×ln=the light absorption ratio b of the energy absorption layer, l1-ln is the thickness of each energy absorption layer structure, and α1-αn is the light absorption rate of each energy absorption layer structure material.

[0014] In some embodiments, the substrate material has a Mohs hardness > 6, and / or a Vickers hardness > 10 GPa, and a fracture toughness < 5. .

[0015] In some embodiments, the substrate material is a crystalline or amorphous material; and / or, the substrate material is quartz glass, borosilicate glass, K9 glass / crown glass, alkali-free glass, ordinary soda-lime glass, germanate glass, tellurate glass, calcium fluoride, magnesium fluoride, quartz crystal, yttrium aluminum garnet (YAG) crystal, yttrium oxide, diamond, zinc oxide, gallium nitride, SiC, SiN, aluminum oxynitride, spinel, transparent zirconium oxide, silicon, or sapphire.

[0016] In some embodiments, the band gap width of the energy absorption layer is ≤2.0 eV; In some embodiments, the energy absorption layer is made of inorganic semiconductor materials of group IV and group III-V, multi-component thin film semiconductor materials of group I-III-VI and group II-VI, perovskite materials, narrow bandgap oxides and chalcogenides, metal oxide thin films and nitride light-absorbing thin films, or ultrathin metal layer thin films. In some embodiments, the energy absorption layer is made of monocrystalline silicon, amorphous silicon / polycrystalline silicon thin film, germanium, gallium arsenide, indium antimonide, copper indium gallium selenide, cadmium telluride, mercury cadmium telluride, organic-inorganic hybrid perovskite, narrow bandgap perovskite, cuprous oxide, antimony sulfide, lead sulfide quantum dots, TiOx, VOx, MoOx, WOx, TiN, TaN, ZrN, Ti, Cr, Ni, Mo, W, or Pt.

[0017] In some embodiments, the substrate includes a first surface and a second surface, the first surface being opposite to the second surface, and the formation of an energy absorption layer at least on the surface of the substrate to be treated specifically involves: A first energy absorption layer is formed on the first surface of the substrate, the first energy absorption layer completely covers the micro-protrusions and micro-pits on the first surface of the substrate, and the energy absorption rate of the first energy absorption layer is greater than the energy absorption rate of the substrate; A second energy absorption layer is formed on the second surface of the substrate. The second energy absorption layer completely covers the micro-protrusions and micro-pits on the second surface of the substrate. The energy absorption rate of the second energy absorption layer is greater than the energy absorption rate of the substrate.

[0018] In some embodiments, irradiating the substrate with an ultrashort pulse laser includes: An ultrashort pulse laser is incident from the upper surface of the first energy absorption layer, penetrates to the second surface of the substrate, and is used to treat the first surface of the substrate, wherein the upper surface of the first energy absorption layer is located away from the first surface of the substrate; and / or, An ultrashort pulse laser is incident from the upper surface of the second energy absorption layer and penetrates to the first surface of the substrate to process the second surface of the substrate. The upper surface of the second energy absorption layer is far from the second surface of the substrate.

[0019] In some embodiments, after irradiating the substrate with an ultrashort pulse laser, the method further includes: removing the energy absorption layer and / or reaction products.

[0020] Accordingly, the present invention also provides a substrate surface treatment apparatus, comprising: A reaction chamber is provided inside, which contains a laser generator and a support structure for placing at least one transparent inorganic substrate; the surface roughness Ra of the substrate to be treated is within 0.1 μm to 20 μm, and at least the surface to be treated of the substrate is covered with an energy absorption layer; the energy absorption layer completely covers the micro-protrusions and micro-pits of the surface to be treated of the substrate, and the energy absorption efficiency of the energy absorption layer is greater than that of the substrate; The laser generator is used to emit an ultrashort pulse laser onto the surface of at least one transparent inorganic substrate to cause a phase explosion in the energy absorption layer and multiphoton absorption in the micro-protrusion region of the surface to be treated on the substrate. Under the action of the phase explosion and multiphoton absorption, the laser performs cold cutting on the micro-protrusion to peel off the micro-protrusion on the surface to be treated without damaging the substrate structure. The wavelength λ of the ultrashort pulse laser is within the range of n*Ra / 10 to n*Ra, where n is the refractive index of the substrate.

[0021] In some embodiments, the laser generator is a femtosecond laser generator or a picosecond laser generator.

[0022] In some embodiments, when the substrate has multiple surfaces to be treated, the position of the support structure can be adjusted, and / or the orientation of the laser emitter head of the laser generator can be adjusted so that the ultrashort pulse laser emitted by the laser generator can be incident from the upper surface of the energy absorption layer on any surface to be treated.

[0023] In some embodiments, the substrate surface treatment apparatus further includes: A vacuum unit connected to the reaction chamber is used to evacuate the reaction chamber and extract particles and reaction impurities removed after the surface treatment of the transparent inorganic substrate. The control unit is used to control the operating state of the laser generator, the wavelength of the emitted laser, the pulse width τ, and the power density based on the substrate material, roughness, and layer structure characteristics of the support structure within the reaction chamber. At least one of frequency.

[0024] In some embodiments, the system further includes a substrate scanning unit, configured to acquire the material, roughness, and layer structure characteristics of the substrate and feed them back to the control unit.

[0025] In some embodiments, the system further includes: at least one reflector disposed on the side of the substrate surface to be treated away from the laser generator, for reflecting laser light that penetrates the substrate and is incident on the reflector back into the substrate; and / or, the mirror orientation of the reflector is adjustable.

[0026] In some embodiments, the laser reflected back to the substrate by the mirror coherently enhances the laser incident on the substrate to improve the removal efficiency of the micro-protrusion region. Specifically, this can be achieved by adjusting the distance between the mirror and the substrate surface, as well as the laser emission frequency. The laser reflected back to the substrate by the mirror can coherently enhance the laser incident on the substrate for the Nth time, where N can be designed as needed.

[0027] Accordingly, this embodiment of the invention also provides a substrate structure that can be surface treated using the above methods, characterized in that it includes: a transparent inorganic substrate and an energy absorption layer covering the surface to be treated on the transparent inorganic substrate; Wherein, the roughness Ra of the surface to be treated of the transparent inorganic substrate is within 0.1 μm to 20 μm; the energy absorption layer completely covers the micro-protrusions and micro-pits of the surface to be treated of the substrate, the energy absorption rate of the energy absorption layer is greater than the energy absorption rate of the substrate, the band gap width of the energy absorption layer is ≤2.0 eV, and the energy absorption layer has a single-layer structure or a multi-layer structure. When the energy absorption layer is a single-layer structure, the thickness of the energy absorption layer is... l = Light absorption ratio of energy absorption layer b / Light absorption rate of energy absorption layer material α; The energy absorption layer has a multi-layer structure, α1 ×l 1 + α2 ×l2 ......+αn ×ln = Light absorption ratio of the energy absorption layer, b l 1 - ln Let α1 be the thickness of each energy absorption layer structure, and α1-αn be the light absorption rate of each energy absorption layer structure material.

[0028] Compared with the prior art, the technical solution of the present invention has the following advantages: In the technical solution of this invention, an energy absorption layer is formed on the surface of a transparent inorganic substrate. The energy absorption layer completely covers the micro-protrusions and micro-pits on the surface of the substrate, and its energy absorption efficiency is greater than that of the substrate. The substrate is then irradiated with an ultrashort pulse laser.

[0029] Because the pulse width of an ultrashort pulse laser is much smaller than the thermal diffusion time of the energy absorption layer, such as a femtosecond laser or a picosecond laser, the irradiated laser can perform cold processing on the energy absorption layer material and the substrate. After the energy absorption layer absorbs the energy of the pulse laser, it does not have time to undergo thermal diffusion. The energy absorption layer material explodes and vaporizes instantly to form plasma, and forms a plasma shock wave and / or an outwardly expanding plasma plume, that is, the energy absorption layer undergoes a phase explosion. The mechanical impact force generated by the plasma shock wave and / or the plasma plume acts on the micro-protrusions on the surface of the substrate.

[0030] Furthermore, for substrates with surface roughness Ra ranging from 0.1 μm to 20 μm, when the wavelength λ of the ultrashort pulse laser is within the range of n*Ra / 10 to n*Ra, in the micro-protrusion region of the substrate surface, after the pulse laser penetrates the surface to be processed, the light is focused below the micro-protrusion region due to light refraction and focusing effect of the micro-protrusion. This, to a certain extent, increases the power density and photon energy of the laser, making multiphoton absorption more likely to occur in the micro-protrusion region. In contrast, in the micro-pit region of the substrate, the light is dispersed, thus reducing the laser power density and photon energy in the micro-pit region. Compared to the micro-protrusion region, the probability of multiphoton absorption in the micro-pit region is significantly reduced. Similarly, for flat surface areas, the probability of multiphoton absorption is also lower than that in micro-protrusion regions.

[0031] In the embodiments of this invention, the micro-protrusion regions of the transparent inorganic substrate are processed under the combined effects of phase explosion impact and multiphoton absorption. The molecular chemical bonds of the micro-protrusion regions are broken, thereby allowing the particles in the micro-protrusion regions to be stripped away. Meanwhile, the smooth surface regions and micro-pit regions do not experience or experience very little multiphoton absorption, resulting in minimal damage to the substrate structure. In other words, this invention can avoid catastrophic brittle fracture of the material along the cleavage plane during laser processing without damaging the substrate structure, thus reducing the roughness of the transparent inorganic substrate. Attached Figure Description

[0032] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic flowchart of an exemplary substrate surface treatment method consistent with some embodiments of the present invention.

[0033] Figure 2 This is a schematic diagram illustrating the principle of an exemplary substrate surface treatment method consistent with some embodiments of the present invention. Detailed Implementation

[0034] The embodiments of this application are described in detail below, with examples of these embodiments shown in the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0035] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0036] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are open-ended expressions, meaning they include what is specified in this application but do not exclude other aspects.

[0037] In the description of this application, all figures disclosed herein, whether or not the words "approximately" or "about" are used, are approximate values. Each figure may vary by less than 10% or by a difference that is considered reasonable by one of the art, such as 1%, 2%, 3%, 4%, or 5%.

[0038] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0039] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0040] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0041] As described in the background section, current laser processing techniques are highly susceptible to inducing catastrophic brittle fracture along cleavage planes for micron- and submicron-level surface finishing. The inventors have discovered that this problem arises because current methods for improving micron- and submicron-level surface roughness primarily utilize CO2 laser polishing, achieving nm- or submicron-level surface roughness. However, CO2 laser polishing uses infrared lasers to melt an extremely thin layer of the material surface, which then solidifies after leveling due to surface tension, thereby reducing surface roughness. Its main goal is to rapidly improve rough surfaces (Ra of several micrometers to tens of micrometers) to the submicron level (Ra of 0.1 μm-1 μm). However, CO2 laser polishing is a thermal processing method, and its high-temperature melting characteristics inevitably lead to high residual thermal stress and mid-frequency ripples. This is particularly problematic for crystalline hard and brittle materials, where this technique is highly prone to inducing catastrophic brittle fracture along cleavage planes and makes it difficult to maintain the edge surface accuracy of components.

[0042] To address the aforementioned technical problems, this invention provides a substrate structure, a substrate surface treatment method, and a treatment apparatus. The method involves forming an energy absorption layer on the substrate surface to be treated, and then irradiating the substrate with an ultrashort pulse laser to induce a phase explosion in the energy absorption layer. This causes multiphoton absorption in the micro-protrusion areas of the substrate surface to be treated. Under the combined effect of the phase explosion and multiphoton absorption, the laser performs cold cutting on the micro-protrusions to peel them off the surface to be treated without damaging the substrate structure.

[0043] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0044] refer to Figure 1 This illustrates a schematic flowchart of an exemplary substrate surface treatment method consistent with some embodiments of the present invention. (See reference...) Figure 2 The diagram illustrates an exemplary substrate surface treatment principle consistent with some embodiments of the present invention.

[0045] The substrate surface treatment method disclosed in this invention includes the following steps: Step S1:1: Provide a transparent inorganic substrate, the roughness Ra of the surface to be treated of the substrate being within 0.1 μm to 20 μm. In other embodiments, the roughness Ra of the surface to be treated of the substrate is within 0.1 μm to 20 μm.

[0046] A transparent inorganic substrate is a substrate that is transparent to a certain wavelength range. In this embodiment, the transparent inorganic substrate is transparent to the ultraviolet-near-infrared light range, for example, transparent to light with wavelengths between 190 nm and 1100 nm. The transparent inorganic substrate material in this embodiment can be a crystalline or amorphous material.

[0047] Transparent inorganic substrates made of amorphous materials are mainly glass-like, such as quartz glass (fused silica SiO2), borosilicate glass (Pyrex, etc.), K9 glass / crown glass, alkali-free glass (glass for display substrates), ordinary soda-lime glass, as well as germanate glass, tellurate glass, etc. Their material characteristics are irregular structure, isotropic, uniform refractive index, poor thermal conductivity, high brittleness, large heat-affected zone during laser processing, and easy generation of microcracks.

[0048] Transparent inorganic substrates made of crystalline materials are mainly single-crystal materials, such as silicon, sapphire (α-Al₂O₃), calcium fluoride (CaF₂), magnesium fluoride (MgF₂), quartz crystal (crystal, α-SiO₂), yttrium aluminum garnet (YAG) crystal (Nd:YAG, etc.), yttrium oxide (Y₂O₃), diamond, zinc oxide (ZnO), gallium nitride (GaN) (optoelectronic substrates), SiC, SiN, aluminum oxynitride (AlON), spinel (MgAl₂O₄), and transparent zirconium oxide (ZrO₂). These materials possess advantages such as high hardness, high strength, and good optical properties, but their fracture toughness remains relatively low and exhibits significant anisotropy. In laser processing, crystalline materials, due to their high hardness and low toughness, are prone to problems such as interplanar cracking, low processing efficiency, and high surface roughness.

[0049] In general, transparent inorganic substrate materials typically exhibit high transmittance to visible light and infrared lasers. However, due to the mismatch between the electronic energy level structure of the atoms or molecules within these transparent materials and the photon energy of visible light and nearby wavelengths, photons cannot be effectively absorbed, resulting in a low light absorption coefficient. This makes it difficult for conventional lasers to effectively deposit energy, hindering laser processing. Furthermore, transparent inorganic substrate materials share common characteristics such as high hardness, poor fracture toughness, and significant anisotropy in thermal stability and mechanical properties, posing technical challenges in laser precision machining, including difficulties in energy coupling, severe thermal damage, and susceptibility to cracking and edge chipping.

[0050] In some embodiments, the transparent inorganic substrate material has a Mohs hardness > 6, and / or a Vickers hardness > 10 GPa, and a fracture toughness < 5. For example, sapphire has a Mohs hardness of 9 and a fracture toughness of 1.8-2.2. .

[0051] As mentioned above, transparent inorganic substrates (such as glass, quartz, sapphire, single-crystal fluorides, YAG, etc.) exhibit extremely low linear absorption rates for visible and near-infrared lasers, making direct and effective processing difficult with conventional thermal lasers. Processing on these substrates primarily relies on the nonlinear absorption and local energy deposition mechanisms induced by ultrashort pulse lasers. The nonlinear absorption mechanism includes nonlinear optical effects such as multiphoton absorption, tunneling ionization, and avalanche ionization. Local energy deposition refers to the rapid deposition of energy within a very small volume, forming an instantaneous high-temperature, high-pressure, and high-density plasma. This causes the material to melt, vaporize, photodecompose, or undergo phase transitions, accompanied by plasma shock waves and micro-explosions (i.e., phase explosions), achieving material removal, modification, or internal modification. Due to the extremely short processing time and limited heat diffusion, thermal damage and microcracks can be significantly suppressed, achieving near-cold processing and greatly improving the processing accuracy and surface quality of transparent and brittle materials.

[0052] Furthermore, for scenarios where nonlinear absorption is difficult to achieve directly, high-absorption functional thin films can be deposited on the substrate surface to improve laser utilization through interfacial energy coupling, enabling efficient laser processing of transparent substrates without affecting laser penetration and focusing.

[0053] Step S12: An energy absorption layer is formed at least on the surface to be treated of the substrate, the energy absorption layer completely covering the micro-protrusions and micro-pits on the surface to be treated of the substrate, and the energy absorption rate of the energy absorption layer is greater than the energy absorption rate of the substrate.

[0054] In other words, by using an energy absorption layer as a high-absorption thin film, the energy absorption layer in this embodiment has the characteristics of not blocking the laser from penetrating the substrate to be treated surface to achieve focusing, improving the energy coupling between the laser and the interface, but not destroying the light transmission and focusing of the substrate. Furthermore, the absorption coefficient of the energy absorption layer is greater than that of the substrate, so that when a phase explosion occurs in the energy absorption layer, the substrate material can maintain basic structural stability, that is, the substrate material does not undergo a phase explosion.

[0055] In this embodiment, the bandgap width of the energy absorption layer is typically around 2.0 eV or less. The material of the energy absorption layer can be a group IV or III-V inorganic semiconductor material, such as single-crystal silicon, amorphous silicon / polycrystalline silicon thin films (a-Si, poly-Si), germanium (Ge), gallium arsenide (GaAs), and indium antimonide (InSb). The material of the energy absorption layer can also be a group I-III-VI or II-VI multi-component thin-film semiconductor material, such as copper indium gallium selenide (CIGS), cadmium telluride (CdTe), and mercury cadmium telluride (HgCdTe). The material of the energy absorption layer can also be a novel perovskite material, such as organic-inorganic hybrid perovskites (e.g., MAPbI3) and narrow-bandgap perovskites (tin-based Pb-Sn mixture). The material of the energy absorption layer can also be a narrow-bandgap oxide and chalcogenide, such as cuprous oxide (Cu2O), antimony sulfide (Sb2S3), lead sulfide (PbS) quantum dots, etc.

[0056] The energy absorption layer can also be made of metal oxide thin films and nitride light-absorbing thin films, such as TiOx, VOx, MoOx, WOx, TiN, TaN, ZrN, etc. The energy absorption layer can also be made of ultrathin metal layers, such as Ti, Cr, Ni, Mo, W, Pt, etc.

[0057] Furthermore, in order to achieve uniformity in the treatment of the substrate surface and ensure the treatment effect, the thickness of the energy absorption layer needs to be able to completely cover the micro-protrusions and micro-pits on the substrate surface to be treated.

[0058] Step S13: Irradiate the substrate with an ultrashort pulse laser to cause a phase explosion in the energy absorption layer and multiphoton absorption in the micro-protrusion area of ​​the surface to be treated on the substrate. Under the action of the phase explosion and multiphoton absorption, the laser performs cold cutting on the micro-protrusion to peel off the micro-protrusion on the surface to be treated without damaging the substrate structure; wherein, the wavelength λ of the ultrashort pulse laser is within the range of n*Ra / 10 to n*Ra, where n is the refractive index of the substrate.

[0059] When the laser wavelength λ is within the range of n*Ra / 10 to n*Ra, after the laser passes through the micro-protrusion area of ​​the substrate surface to be treated, it converges below the micro-protrusion, thereby increasing the laser power density and photon energy, making it easier for multiphoton absorption to occur in the micro-protrusion area. In this embodiment, the laser wavelength range is in the ultraviolet-near infrared range, such as a laser with a wavelength in the range of 190nm-1100nm.

[0060] In this embodiment, the laser pulse width τ prevents thermal ablation of the energy absorption layer. The laser can be a nanosecond laser, a femtosecond laser, or a picosecond laser, as long as it achieves a near-cold processing effect under the energy coupling effect of the energy absorption layer. In other embodiments, femtosecond lasers or picosecond lasers are preferred to increase the probability of multiphoton absorption.

[0061] In order to achieve multiphoton absorption in the micro-bump region, the power density of the laser in this embodiment is [specifically, the required power density]. ≈ Threshold light intensity at which the substrate material undergoes multiphoton absorption In other embodiments, to avoid multiphoton absorption in flat and micro-depression regions of the substrate, the power density of the laser is... Light intensity less than the threshold for multiphoton absorption by the substrate material Furthermore, the laser beam irradiating the micro-protrusion is focused by the micro-protrusion, resulting in enhanced light intensity that reaches the threshold light intensity. This allows for processing only the micro-protruding areas.

[0062] In some embodiments, to further improve the multiphoton absorption rate, a high numerical aperture (NA) objective lens is used to focus the laser into an extremely small volume at the micrometer / submicrometer scale, forming a threshold intensity only at the focal center. Extremely high light intensity.

[0063] After the substrate surface is treated using the method of this embodiment, the roughness Ra of the surface to be treated on the transparent inorganic substrate is within 1nm-10nm, and the catastrophic brittle fracture of the material along the cleavage plane during laser processing is avoided, thereby reducing the roughness of the transparent inorganic substrate.

[0064] In this embodiment of the invention, an energy absorption layer material and a substrate are irradiated with an ultrashort pulse laser. Since the pulse width of the ultrashort pulse is less than or equal to the thermal diffusion time of the energy absorption layer, the energy absorption layer absorbs the energy of the pulse laser and, before thermal diffusion can occur, nonlinear absorption is triggered. The energy absorption layer material instantly explodes and vaporizes to form plasma, and forms a plasma shock wave and / or an outwardly expanding plasma plume, i.e., the energy absorption layer undergoes a phase explosion. The mechanical impact force generated by the plasma shock wave and / or the plasma plume acts on the micro-protrusions on the surface of the substrate.

[0065] Furthermore, for substrates with surface roughness Ra ranging from 0.1 μm to 20 μm, when the wavelength λ of the ultrashort pulse laser is within the range of n*Ra / 10 to n*Ra, in the micro-protrusion region of the substrate surface, after the pulse laser penetrates the surface to be processed, the light is focused below the micro-protrusion region due to light refraction and focusing effect of the micro-protrusion. This, to a certain extent, increases the power density and photon energy of the laser, making multiphoton absorption more likely to occur in the micro-protrusion region. In contrast, in the micro-pit region of the substrate, the light is dispersed, thus reducing the laser power density and photon energy in the micro-pit region. Compared to the micro-protrusion region, the probability of multiphoton absorption in the micro-pit region is significantly reduced. Similarly, for flat surface areas, the probability of multiphoton absorption is also lower than that in micro-protrusion regions.

[0066] In the embodiments of this invention, the micro-protrusion regions of the transparent inorganic substrate are processed under the combined effects of phase explosion impact and multiphoton absorption. The molecular chemical bonds of the micro-protrusion regions are broken, thereby allowing the particles in the micro-protrusion regions to be stripped away. Meanwhile, the smooth surface regions and micro-pit regions do not experience or experience very little multiphoton absorption, resulting in minimal damage to the substrate structure. In other words, this invention can avoid catastrophic brittle fracture of the material along the cleavage plane during laser processing without damaging the substrate structure, thus reducing the roughness of the transparent inorganic substrate.

[0067] In some embodiments, after irradiating the substrate with an ultrashort pulse laser, to ensure the cleanliness of the substrate, the process further includes removing the energy absorption layer. The energy absorption layer material can be removed by cleaning or by removing particles from the processing space through vacuuming.

[0068] In some embodiments, the energy absorption layer can be a single-layer structure or a multi-layer structure. The pre-designed light absorption ratio b of the energy absorption layer... × Laser power density × Laser spot area S × Laser pulse width τ = laser power density × Laser spot area S × Thickness of energy absorption layer l× Laser pulse width τ × The light absorption rate α of the energy absorption layer material; therefore, when the energy absorption layer is a single-layer structure, the thickness of the energy absorption layer... l = Light absorption ratio of the energy absorption layer (b) / light absorption rate of the energy absorption layer material (α). When the energy absorption layer is a multilayer structure, α1 ×l 1 + α2 ×l2 ......+αn ×ln = Light absorption ratio of the energy absorption layer, b l 1 -ln Let α1 be the thickness of each energy absorption layer structure, and α1-αn be the light absorption rate of each energy absorption layer structure material.

[0069] In some embodiments, the transparent inorganic substrate has multiple surfaces to be treated, requiring the formation of an energy absorption layer on each surface and the laser irradiation of the energy absorption layer on each surface. The following description uses an example of a transparent inorganic substrate with two surfaces to be treated.

[0070] The transparent inorganic substrate includes a first surface and a second surface to be treated, the first surface and the second surface being opposite to each other. Specifically, an energy-absorbing layer is formed at least on the surface to be treated of the substrate. A first energy absorption layer is formed on the first surface of the substrate, the first energy absorption layer completely covers the micro-protrusions and micro-pits on the first surface of the substrate, and the energy absorption rate of the first energy absorption layer is greater than the energy absorption rate of the substrate; A second energy absorption layer is formed on the second surface of the substrate. The second energy absorption layer completely covers the micro-protrusions and micro-pits on the second surface of the substrate. The energy absorption rate of the second energy absorption layer is greater than the energy absorption rate of the substrate.

[0071] The method of irradiating the substrate with an ultrashort pulse laser includes: An ultrashort pulse laser is incident from the upper surface of the first energy absorption layer, penetrating to the second surface of the substrate, to treat the first surface of the substrate. The upper surface of the first energy absorption layer is the surface of the first energy absorption layer that is away from the first surface of the substrate; and / or, An ultrashort pulse laser is incident from the upper surface of the second energy absorption layer and penetrates to the first surface of the substrate to process the second surface of the substrate. The upper surface of the second energy absorption layer is the surface of the second energy absorption layer that is far away from the second surface of the substrate.

[0072] This embodiment achieves the processing of multiple surfaces of the substrate by forming energy absorption layers on each surface to be processed and irradiating the energy absorption layers on each surface to be processed with laser.

[0073] Some embodiments of the present invention disclose a substrate processing apparatus used to implement the above-described substrate processing method. The apparatus includes: A reaction chamber is provided inside, which contains a laser generator and a support structure for placing at least one transparent inorganic substrate; the surface roughness Ra of the substrate to be treated is within 0.1 μm to 20 μm, and at least the surface to be treated of the substrate is covered with an energy absorption layer; the energy absorption layer completely covers the micro-protrusions and micro-pits of the surface to be treated of the substrate, and the energy absorption efficiency of the energy absorption layer is greater than that of the substrate; The laser generator is used to emit an ultrashort pulse laser onto the surface to be treated of at least one transparent inorganic substrate, causing a phase explosion in the energy absorption layer and multiphoton absorption in the micro-protrusion region of the surface to be treated. Under the action of the phase explosion and multiphoton absorption, the laser performs cold cutting on the micro-protrusion to peel off the micro-protrusion on the surface to be treated without damaging the substrate structure; wherein, the wavelength λ of the ultrashort pulse laser is within the range of n*Ra / 10 to n*Ra, where n is the refractive index of the substrate.

[0074] In some embodiments, the laser generator is a femtosecond laser generator or a picosecond laser generator.

[0075] In some embodiments, when the substrate has multiple surfaces to be treated, the position of the support structure can be adjusted, and / or the orientation of the laser emitter head of the laser generator can be adjusted so that the ultrashort pulse laser emitted by the laser generator can be incident from the upper surface of the energy absorption layer on any of the surfaces to be treated. The position and laser emission orientation can be adjusted by mounting the support structure and / or the laser generator on a guide rail or a rotating mechanism.

[0076] In some embodiments, in order to remove impurity particles and the like from the reaction chamber, a vacuum pumping unit connected to the reaction chamber is further included, for evacuating the reaction chamber and extracting particles and reaction impurities removed after the surface treatment of the transparent inorganic substrate.

[0077] The control unit is used to control the operating state of the laser generator, the wavelength of the emitted laser, the pulse width τ, and the power density based on the substrate material, roughness, and layer structure characteristics of the support structure within the reaction chamber. At least one of the following: laser frequency, laser frequency, and laser frequency. The laser frequency affects the efficiency of substrate surface treatment, and the treatment efficiency can be controlled by adjusting the laser frequency.

[0078] In some embodiments, the system further includes: a substrate scanning unit, configured to acquire the material, roughness, and layer structure characteristics of the substrate and feed them back to the control unit. In some embodiments, the system further includes: at least one reflector disposed on the side of the substrate surface to be treated away from the laser generator, configured to reflect laser light that penetrates the substrate and is incident on the reflector back into the substrate; and / or, the mirror orientation of the reflector is adjustable.

[0079] In some embodiments, the laser reflected back to the substrate by the mirror coherently enhances the laser incident on the substrate to improve the removal efficiency of the micro-protrusion region. Specifically, this can be achieved by adjusting the distance between the mirror and the substrate surface, as well as the laser emission frequency. The laser reflected back to the substrate by the mirror can coherently enhance the laser incident on the substrate for the Nth time, where N can be designed as needed.

[0080] The substrate surface treatment device disclosed in this invention can adapt different laser processing parameters in real time according to information such as the material, roughness, and layer structure characteristics of the transparent inorganic substrate to be treated, as well as the material of the energy absorption layer, thereby improving the versatility of the surface treatment device.

[0081] Some embodiments of the present invention also disclose a substrate structure, on which the surface treatment method described in the above embodiments can be applied to perform surface treatment on the transparent inorganic substrate in the substrate structure of this embodiment. Specifically, the substrate structure includes: a transparent inorganic substrate and an energy absorption layer covering the surface to be treated of the transparent inorganic substrate.

[0082] In this embodiment, the surface roughness Ra of the transparent inorganic substrate to be treated is within 0.1 μm to 20 μm; the energy absorption layer completely covers the micro-protrusions and micro-pits of the surface to be treated on the substrate, and the energy absorption rate of the energy absorption layer is greater than the energy absorption rate of the substrate. In some embodiments, the surface roughness Ra of the transparent inorganic substrate to be treated is within 0.1 μm to 10 μm.

[0083] The band gap width of the energy absorption layer is ≤2.0eV, and the energy absorption layer has a single-layer structure or a multi-layer structure.

[0084] In some embodiments, the energy absorption layer is a single-layer structure, and the thickness of the energy absorption layer is... l = Light absorption ratio of the energy absorption layer b / Light absorption rate of the energy absorption layer material α.

[0085] In some embodiments, the energy absorption layer is a multilayer structure, α1 ×l 1 + α2 ×l2 ......+αn ×ln =The light absorption ratio of the energy absorption layer, b l 1- ln Let α1 be the thickness of each energy absorption layer structure, and α1-αn be the light absorption rate of each energy absorption layer structure material.

[0086] In some embodiments, the surfaces to be treated on the transparent inorganic substrate in the substrate structure are a first surface and a second surface facing away from each other, and both the first and second surfaces are covered with an energy-absorbing layer. In other embodiments, the surfaces to be treated on the transparent inorganic substrate in the substrate structure can be any number of surfaces, and the substrate structure can also be of any shape with multiple surfaces; the present invention does not specifically limit this.

[0087] In this embodiment, the substrate structure covers the surface to be treated of a transparent inorganic substrate with an energy absorption layer. This energy absorption layer is a high-absorption thin film, and its material and thickness do not prevent the laser from penetrating the surface to be treated and achieving focusing. Thus, after the laser irradiates through the energy absorption layer and irradiates the substrate, the energy coupling between the laser and the interface can be improved without destroying the light-transmitting and focusing characteristics of the substrate. Furthermore, the absorption coefficient of the energy absorption layer is greater than that of the substrate, so that when the energy absorption layer undergoes a phase explosion during laser irradiation, the substrate material does not undergo a phase explosion, that is, the substrate material maintains basic structural stability.

[0088] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

[0089] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for treating a substrate surface, characterized in that, include: A transparent inorganic substrate is provided, wherein the surface roughness Ra of the substrate to be treated is within the range of 0.1 μm to 20 μm; An energy absorption layer is formed at least on the surface to be treated of the substrate, the energy absorption layer completely covering the micro-protrusions and micro-pits on the surface to be treated of the substrate, and the energy absorption coefficient of the energy absorption layer is greater than the energy absorption coefficient of the substrate. The substrate is irradiated with an ultrashort pulse laser to induce a phase explosion in the energy absorption layer and multiphoton absorption in the micro-protrusion region of the substrate's surface to be treated. Under the combined effects of the phase explosion and multiphoton absorption, the laser performs cold cutting on the micro-protrusions to remove them from the surface to be treated without damaging the substrate structure. The wavelength λ of the ultrashort pulse laser is within the range of n*Ra / 10 to n*Ra, causing the laser to converge below the micro-protrusions after passing through them, thereby increasing the laser's power density and photon energy. n is the refractive index of the substrate.

2. The substrate surface treatment method as described in claim 1, characterized in that, After surface treatment, the roughness Ra of the substrate surface to be treated is within 1nm-10nm.

3. The substrate surface treatment method as described in claim 2, characterized in that, The pulse width τ of the laser prevents thermal ablation of the energy absorption layer.

4. The substrate surface treatment method as described in claim 3, characterized in that, The laser is a femtosecond laser or a picosecond laser.

5. The substrate surface treatment method as described in claim 3, characterized in that, The power density of the laser ≈ Threshold light intensity at which the substrate material undergoes multiphoton absorption .

6. The substrate surface treatment method as described in claim 5, characterized in that, The power density of the laser Light intensity less than the threshold for multiphoton absorption by the substrate material Furthermore, the laser beam irradiating the micro-protrusion is focused by the micro-protrusion, resulting in increased intensity of the laser beam reaching the threshold intensity. .

7. The substrate surface treatment method as described in claim 5, characterized in that, The energy absorption layer may be a single-layer structure or a multi-layer structure. When the energy absorption layer is a single-layer structure, the thickness of the energy absorption layer is... l = Light absorption ratio of energy absorption layer b / Light absorption rate of energy absorption layer material α; When the energy absorption layer is a multi-layer structure, α1 ×l 1 + α2 ×l2 ......+αn ×ln = Light absorption ratio of the energy absorption layer, b l 1 - ln Let α1 be the thickness of each energy absorption layer structure, and α1-αn be the light absorption rate of each energy absorption layer structure material.

8. The substrate surface treatment method as described in claim 1, characterized in that, The substrate material has a Mohs hardness > 6 and / or a Vickers hardness > 10 GPa, and a fracture toughness < 5. .

9. The substrate surface treatment method as described in claim 8, characterized in that, The substrate material is either crystalline or amorphous.

10. The substrate surface treatment method as described in claim 9, characterized in that, The substrate material is quartz glass, borosilicate glass, crown glass, alkali-free glass, ordinary soda-lime glass, germanate glass, tellurate glass, calcium fluoride, magnesium fluoride, quartz crystal, yttrium aluminum garnet (YAG) crystal, yttrium oxide, diamond, zinc oxide, gallium nitride, SiC, SiN, aluminum oxynitride, spinel, transparent zirconium oxide, silicon, or sapphire.

11. The substrate surface treatment method as described in claim 1, characterized in that, The band gap width of the energy absorption layer is ≤2.0eV.

12. The substrate surface treatment method as described in claim 11, characterized in that, The energy absorption layer is made of group IV inorganic semiconductor materials, group III-V inorganic semiconductor materials, group I-III-VI multi-component thin-film semiconductor materials, group II-VI multi-component thin-film semiconductor materials, perovskite materials, narrow bandgap oxides, narrow bandgap chalcogenides, metal oxide thin films, metal nitride light-absorbing thin films, or ultrathin metal layer thin films.

13. The substrate surface treatment method as described in claim 11, characterized in that, The energy absorption layer is made of monocrystalline silicon, amorphous silicon thin film, polycrystalline silicon thin film, germanium, gallium arsenide, indium antimonide, copper indium gallium selenide, cadmium telluride, mercury cadmium telluride, organic-inorganic hybrid perovskite, narrow bandgap perovskite, cuprous oxide, antimony sulfide, lead sulfide quantum dots, TiOx, VOx, MoOx, WOx, TiN, TaN, ZrN, Ti, Cr, Ni, Mo, W, or Pt.

14. The substrate surface treatment method according to any one of claims 1-13, characterized in that, The substrate includes a first surface and a second surface to be treated, the first surface and the second surface being opposite to each other, and the formation of an energy absorption layer at least on the surface to be treated of the substrate specifically involves: A first energy absorption layer is formed on the first surface of the substrate, the first energy absorption layer completely covers the micro-protrusions and micro-pits on the first surface of the substrate, and the energy absorption rate of the first energy absorption layer is greater than the energy absorption rate of the substrate; A second energy absorption layer is formed on the second surface of the substrate. The second energy absorption layer completely covers the micro-protrusions and micro-pits on the second surface of the substrate. The energy absorption rate of the second energy absorption layer is greater than the energy absorption rate of the substrate.

15. The substrate surface treatment method as described in claim 14, characterized in that, The method of irradiating the substrate with an ultrashort pulse laser includes: An ultrashort pulse laser is incident from the upper surface of the first energy absorption layer, penetrates to the second surface of the substrate, and is used to treat the first surface of the substrate, wherein the upper surface of the first energy absorption layer is located away from the first surface of the substrate; or, An ultrashort pulse laser is incident from the upper surface of the second energy absorption layer and penetrates to the first surface of the substrate to process the second surface of the substrate. The upper surface of the second energy absorption layer is far from the second surface of the substrate.

16. The substrate surface treatment method as described in claim 1, characterized in that, After irradiating the substrate with an ultrashort pulse laser, the method further includes: removing the energy absorption layer and / or reaction products.

17. A substrate surface treatment apparatus, characterized in that, include: A reaction chamber is provided inside, which contains a laser generator and a support structure for placing at least one transparent inorganic substrate; the surface roughness Ra of the substrate to be treated is within 0.1 μm to 20 μm, and at least the surface to be treated of the substrate is covered with an energy absorption layer; the energy absorption layer completely covers the micro-protrusions and micro-pits of the surface to be treated of the substrate, and the energy absorption efficiency of the energy absorption layer is greater than that of the substrate; The laser generator is used to emit an ultrashort pulse laser onto the surface to be treated of at least one transparent inorganic substrate, causing a phase explosion in the energy absorption layer and multiphoton absorption in the micro-protrusion region of the surface to be treated. Under the action of the phase explosion and multiphoton absorption, the laser performs cold cutting on the micro-protrusion to peel off the micro-protrusion on the surface to be treated without damaging the substrate structure. The wavelength λ of the ultrashort pulse laser is within the range of n*Ra / 10 to n*Ra, so that after the laser passes through the micro-protrusion region, it converges below the micro-protrusion to improve the power density and photon energy of the laser, where n is the refractive index of the substrate.

18. The substrate surface treatment apparatus as claimed in claim 17, characterized in that, The laser generator is a femtosecond laser generator or a picosecond laser generator.

19. The substrate surface treatment apparatus as claimed in claim 17, characterized in that, When the substrate has multiple surfaces to be treated, the position of the support structure can be adjusted, and / or the orientation of the laser emitter head of the laser generator can be adjusted so that the ultrashort pulse laser emitted by the laser generator can be incident from the upper surface of the energy absorption layer on any surface to be treated.

20. The substrate surface treatment apparatus as claimed in claim 17, characterized in that, Also includes: A vacuum unit connected to the reaction chamber is used to evacuate the reaction chamber and extract particles and reaction impurities removed after the surface treatment of the transparent inorganic substrate. The control unit is used to control the operating state of the laser generator, the wavelength of the emitted laser, the pulse width τ, and the power density based on the substrate material, roughness, and layer structure characteristics of the support structure within the reaction chamber. At least one of frequency.

21. The substrate surface treatment apparatus as claimed in claim 20, characterized in that, Also includes: The substrate scanning unit is used to acquire the material, roughness, and layer structure characteristics of the substrate and feed them back to the control unit.

22. The substrate surface treatment apparatus as claimed in claim 17, characterized in that, Also includes: At least one reflector is disposed on the side of the substrate surface to be treated away from the laser generator, for reflecting laser light that penetrates the substrate and is incident on the reflector back into the substrate.

23. The substrate surface treatment apparatus as claimed in claim 22, characterized in that, The mirror's orientation is adjustable.

24. A substrate structure, surface-treated using the method described in any one of claims 1-16, characterized in that, include: A transparent inorganic substrate and an energy-absorbing layer covering the surface of the transparent inorganic substrate to be treated; Wherein, the roughness Ra of the surface to be treated of the transparent inorganic substrate is within 0.1 μm to 20 μm; the energy absorption layer completely covers the micro-protrusions and micro-pits of the surface to be treated of the substrate, the energy absorption rate of the energy absorption layer is greater than the energy absorption rate of the substrate, the band gap width of the energy absorption layer is ≤2.0 eV, and the energy absorption layer is a single-layer structure or a multi-layer structure. When the energy absorption layer is a single-layer structure, the thickness of the energy absorption layer is... l = Light absorption ratio of energy absorption layer b / Light absorption rate of energy absorption layer material α; When the energy absorption layer is a multi-layer structure, α1 ×l 1 + α2 ×l2 ......+αn ×ln =The light absorption ratio of the energy absorption layer, b l 1 - ln Let α1 be the thickness of each energy absorption layer structure, and α1-αn be the light absorption rate of each energy absorption layer structure material.

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