Grinding-assisted graphical etching method for lithium niobate and application of grinding-assisted graphical etching method

Abstract

The invention discloses a grinding-assisted graphical etching method for lithium niobate and application of the grinding-assisted graphical etching method, and belongs to the technical field of micro-nano machining. According to the technical scheme, the method comprises the steps that a lithium niobate substrate is provided, and a patterned metal mask layer is prepared on the surface of one side of the lithium niobate substrate; carrying out selective grinding and etching on one surface, with the metal mask layer, of the lithium niobate substrate by using an abrasive so as to form an etching region on the lithium niobate substrate, and removing the metal mask layer; wherein the hardness of the metal mask layer is greater than or equal to that of the grinding material, and the hardness of the grinding material is greater than or equal to that of the lithium niobate substrate. According to the method, the characteristic that the hardness of the grinding material is higher than that of the lithium niobate and lower than that of the metal mask is utilized, selective etching of the lithium niobate can be completed, damage of isotropy of wet etching to the transverse size and lithium niobate cleavage possibly caused by wet etching are avoided, the time cost is saved, the preparation process is optimized, and the production efficiency is improved. And the process stability is ensured.

Description

Technical Field

[0001] This application relates to a grinding-assisted patterned etching method for lithium niobate and its application, belonging to the field of micro-nano fabrication technology. Background Technology

[0002] With the rapid development of 5G / 6G, artificial intelligence, quantum technology and other fields, the market demand for lithium niobate continues to grow. According to industry forecasts, the market size of thin-film lithium niobate alone will exceed 10 billion yuan in the next few years, becoming an important growth point for the new materials industry. The core value of lithium niobate stems from its combination of multiple excellent properties, which makes it stand out among many materials: (1) Piezoelectric properties: It has extremely high piezoelectric coefficient and electromechanical coupling coefficient, which can efficiently realize the mutual conversion of mechanical energy and electrical energy. It is an ideal material for preparing high-frequency ultrasonic transducers, piezoelectric sensors and radio frequency filters; (2) Electro-optic properties: It has significant electro-optic effect (refractive index changes with external electric field), which can quickly modulate optical signals. It is the core material of optical modulator in optical communication, supporting high-speed data transmission of optical fiber communication; (3) Ferroelectric properties: It has stable ferroelectric properties and Curie temperature (about 1210°C), which can be used to prepare non-volatile memory and tunable devices, and can still maintain stable performance in high-temperature environments; (4) Nonlinear optical properties: Strong nonlinear optical effect enables it to realize laser frequency conversion (such as frequency doubling and frequency mixing), which is indispensable in laser technology, quantum optics and other fields; (5) Chemical and thermal stability, resistance to chemical corrosion and high temperature (high Curie temperature), suitable for harsh environments (such as aerospace, automotive electronics and industrial sensing), which broadens the application scenarios.

[0003] However, etching of lithium niobate (LiNbO3) is a core technological challenge in its device fabrication (especially thin-film lithium niobate integrated photonic chips, high-frequency filters, etc.). The challenge stems from the physicochemical properties of the material itself and the stringent requirements of the device for etching precision. The specific challenges can be summarized as follows: (1) extremely high chemical stability, resulting in extremely low wet etching efficiency; (2) crystal anisotropy leading to irregular patterns in dry etching; (3) difficulty in controlling etching selectivity, making the substrate and mask easily damaged; (4) difficulty in controlling surface quality, affecting the optical and electrical performance of the device. Currently, the industry has alleviated some of the problems by optimizing etching gas (such as introducing O2 to adjust plasma activity), improving mask materials (such as thick-layer Si3N4), and controlling plasma energy (low-energy ion beam etching), but has not yet made a complete breakthrough. These challenges have also become key bottlenecks restricting the development of thin-film lithium niobate integrated devices towards higher performance and smaller size, and are currently a research hotspot in the field of materials processing. In addition, micron-level thickness etching is also a current processing challenge. Summary of the Invention

[0004] To address the issue that improving the etching performance of high-precision micro / nano structures using wet etching methods in existing lithium niobate etching technologies relies on novel etching solutions and mask materials, this application provides a polishing-assisted patterned etching method for lithium niobate. The method involves uniformly photoresisting and patterning a lithium niobate wafer, followed by depositing a metal oxide layer (such as Cr). A lift-off process is then used to pattern the metal layer. Next, the wafer is placed on a polishing pad for polishing. The micro-deformation of the polishing pad and the hard mask effect of the metal layer ensure sufficient contact between the polishing particles and the patterned lithium niobate, achieving selective etching. Finally, wet etching is used to completely etch the surface metal mask layer, thus realizing the patterned etching of lithium niobate.

[0005] The technical solution adopted in this application is as follows: According to a first aspect of this application, a method for grinding-assisted patterned etching of lithium niobate is provided, comprising: A lithium niobate substrate is provided, and a patterned metal mask layer is prepared on one side surface of the lithium niobate substrate; The side of the lithium niobate substrate with the metal mask layer is selectively ground and etched using an abrasive to form an etched area on the lithium niobate substrate and to remove the metal mask layer. Wherein, the hardness of the metal mask layer is greater than or equal to the hardness of the abrasive, and the hardness of the abrasive is greater than or equal to the hardness of the lithium niobate substrate.

[0006] Optionally, the material of the metal mask layer is selected from at least one of Cr, W, Mo, and V.

[0007] Optionally, the thickness of the metal mask layer is 100nm~3um.

[0008] Optionally, the abrasive is selected from at least one of SiO2, corundum, CeO2, and ZrO2.

[0009] Optionally, the depth of the etched area is 100 nm to 10 μm.

[0010] Optionally, the fabrication of a patterned metal mask layer on one side surface of the lithium niobate substrate includes: A patterned window is formed by homopolymer photolithography on one side surface of the lithium niobate substrate; The material of the metal mask layer is deposited on the surface of the lithium niobate substrate in the graphics window; Remove the photoresist and metal mask layer material from the area outside the graphics window.

[0011] Optionally, during the homogenization photolithography process, the thickness of the photoresist coating is 0.6 μm to 5 μm.

[0012] Optionally, during the homopolymer photolithography process, the exposure dose is 60 mJ / cm². 2 ~200 mJ / cm 2 .

[0013] Optionally, the method of depositing the metal mask layer on the surface of the lithium niobate substrate in the graphics window is magnetron sputtering or electron beam evaporation.

[0014] Optionally, the lithium niobate substrate is a bulk lithium niobate crystal sheet or a lithium niobate thin film.

[0015] According to a second aspect of this application, an application is provided for the aforementioned grinding-assisted patterned etching method for lithium niobate in the fabrication of optoelectronic devices, MEMS devices, and acoustic filters.

[0016] The beneficial effects of this application include: (1) This application selectively etches lithium niobate wafers by a grinding-assisted method, which avoids the damage to the lateral dimensions caused by the isotropic nature of wet etching and avoids the lithium niobate cleavage that may be caused by wet etching. It also saves time and costs, optimizes the preparation process, and ensures the stability of the process.

[0017] (2) This application utilizes the hardness difference between the abrasive, the metal mask layer and the substrate wafer to achieve selective etching, and also provides an alternative solution for completing such patterning processing on other materials.

[0018] (3) The grinding-assisted patterned etching method for lithium niobate provided in this application is a processing method that does not require wet etching, which avoids the safety hazards caused by acidic liquids during processing and is conducive to continuous operation of equipment. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the fabrication process of the patterned metal layer mask on lithium niobate in this application; Figure 2 This is a process flow diagram of the preparation of the grinding-assisted selective etching process for lithium niobate in this application; Figure 3 This is a process flow diagram of wet etching of lithium niobate in Comparative Example 1 of this application. Detailed Implementation

[0020] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0021] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0022] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0023] The existing etching technologies for lithium niobate mainly include dry etching and wet etching, among which: Dry etching process Dry etching of lithium niobate (LiNbO3, LN) is a key process for preparing high-precision micro and nano structures (such as photonic waveguides, surface acoustic wave devices, electro-optic modulators, etc.). Its technical process is limited by the special physicochemical properties of lithium niobate (high chemical stability, high hardness, and composite oxide composition) and the complex mechanism of plasma etching. There are several core technical problems, as follows: (1) Imbalance in etching rate: The etching rate is low. If chemical etching is the main method (such as using fluorine-based gas), the reaction product of Nb and F (such as NbF5) has good volatility. However, the reaction product of Li and F (LiF) has a high melting point (about 845℃) and poor volatility. It is easy to form a residual layer on the surface, which hinders further etching and results in a low overall rate (usually only a few nm / min). (1) Up to tens of nm / min), which is difficult to meet the efficiency requirements of large-scale production; (2) Imbalance with etching selectivity: poor selectivity. If physical bombardment is enhanced (such as increasing radio frequency power) to remove the residual layer, although the rate can be increased, the mask material (such as metal Cr, SiO2) or substrate (such as sapphire, Si) will be etched at the same time, resulting in a decrease in etching selectivity (the ratio of etching rate of LN to mask / substrate) and damage to pattern accuracy; (3) Difficulty in controlling etching morphology: if the sidewall is tilted or bent, and the incident angle of ions in the plasma is not uniform (such as edge effect), the sidewall will be bombarded non-vertically, forming a tilt; if the oxygen content in the etching gas is too high, it may form low-volatility NbO with Nb. x F y, deposited on the sidewall to form "bow"; surface roughness and pinholes, the uneven distribution of LiF residual layer will lead to local etching obstruction, the uncovered area will be over-bombarded, forming surface unevenness (roughness can reach tens of nm); in addition, the cleavage plane of lithium niobate single crystal (such as (0001) plane) has anisotropy, plasma bombardment may preferentially intensify etching along the cleavage direction, forming pinholes or trenches; insufficient etching depth accuracy, due to the difference in etching rate between Li and Nb, "composition segregation" may occur in the depth direction (such as Li being etched first, Nb enriched), resulting in deviation between the actual etching depth and the design value (error can reach more than 10%), affecting device performance (such as the effective refractive index of optical waveguide); (4) compatibility and loss problem of mask material: although metal masks (such as Cr, Ni) are resistant to physical bombardment, they are easy to react with fluorine-based gases to generate volatile metal fluorides (such as CrF3), resulting in rapid mask loss (when the etching depth is 1 μm, the mask may be consumed by 50%). The above), the edges of the pattern are blurred; the dielectric mask (such as SiO2, photoresist), SiO2 reacts slowly with fluorine-based gas (good etching resistance), but high-energy particles in the plasma will cause SiO2 surface sputtering and contaminate the lithium niobate surface; the photoresist is easily oxidized and decomposed by oxygen free radicals in the plasma, and is only suitable for shallow etching (<200 nm); the compatibility problem between the mask and the substrate, if the lithium niobate is a heteroepitaxial substrate (such as LN-on-insulator, LNOI), the mask material may react with the substrate (such as SiO2 insulating layer), resulting in substrate damage. (5) The etching residue is difficult to completely remove: the LiF and NbO residues remaining on the surface after etching x F y If mask debris (such as CrF3) is not completely removed, it can cause subsequent processes (such as coating and bonding) to fail: conventional cleaning (such as dilute acid immersion) is difficult to dissolve LiF (which has extremely low solubility in water); ultrasonic cleaning may aggravate surface damage (especially in areas where lattice defects already exist); although high-temperature annealing can eliminate some lattice damage, it may cause residues to diffuse into the body, forming deeper contamination.

[0024] The aforementioned technical problems of dry etching process directly restrict the high performance and large-scale production of lithium niobate devices. At present, the industry has gradually overcome these problems by optimizing the etching gas ratio (such as introducing O2 to adjust the volatility of LiF), developing new mask materials (such as diamond thin films), and improving plasma sources (such as inductively coupled plasma ICP to improve ion density uniformity). However, a universally applicable mature solution has not yet been formed.

[0025] wet etching process Wet etching of lithium niobate (LiNbO3, LN) is a process that uses a chemical solution to selectively react with the material surface to dissolve and remove unpatterned areas. It is widely used in the fabrication of low-precision microstructures (such as early surface acoustic wave devices and simple electrode patterns). However, due to the chemical stability of lithium niobate, crystal anisotropy and the inherent characteristics of wet etching, there are several key difficulties in the process, as follows: (1) Insufficient reactivity of the etching solution and low rate: Lithium niobate has extremely strong chemical stability (especially the Nb-O bond energy is as high as 670 kJ / mol), and is inert to most chemical reagents, resulting in a very narrow range of etching solutions and difficulty in increasing the reaction rate. (2) Crystal anisotropy makes morphology control difficult: Lithium niobate is a hexagonal crystal system (space group R3c). The atomic arrangement density and chemical bond exposure of different crystal planes (such as (0001) basal plane and (10-10) prism plane) are significantly different, resulting in strong anisotropy in wet etching (the etching rate difference in different directions can be more than 10 times), which makes it difficult to meet the morphology requirements of high-precision devices. (3) Poor selectivity and compatibility of mask materials: Wet etching depends on the mask (such as photoresist, metal, oxide) to define the pattern. It requires the mask to be stable in the etching solution and not to compete with LN for reaction, but it is difficult to achieve both in practice. (4) Residual reaction products and cleaning challenges: The LiF (low solubility) and Nb fluorides generated by etching (such as H2NbF7 which is easily hydrolyzed to form NbO2F) are prone to forming residues on the surface. LiF is difficult to remove by conventional deionized water cleaning and needs to be soaked in high-concentration nitric acid (HNO3) or hot phosphoric acid (H3PO4), but strong acids will further corrode the LN surface or mask.

[0026] The aforementioned technical challenges of wet etching of lithium niobate stem from the contradiction between the material's chemical stability, crystal anisotropy, and the "chemically dominant" nature of wet etching, making it more suitable for low-precision, shallow-depth device fabrication. For high-precision micro / nano structures (such as photonic integrated chips), dry etching remains the primary technical route. However, wet etching still holds irreplaceable value in low-cost, low-damage scenarios (such as certain sensors). Breakthroughs in its core challenges depend on the development of novel etching solutions (such as composite fluorine-acid systems) and mask materials (such as two-dimensional material masks).

[0027] To address at least one of the aforementioned technical problems, this application involves uniformly photoresisting and patterning on a lithium niobate wafer, followed by depositing a metal oxide layer (such as Cr). A lift-off process is then used to pattern the metal layer. Next, the wafer is placed on a polishing pad for grinding. Utilizing the micro-deformation of the polishing pad and the hard mask effect of the metal layer, the abrasive particles are brought into full contact with the patterned lithium niobate, achieving selective etching of the lithium niobate. Finally, wet etching is used to completely etch the surface metal mask layer, achieving patterned etching of the lithium niobate.

[0028] According to one embodiment of this application, a method for grinding-assisted patterning etching of lithium niobate includes: A lithium niobate substrate is provided, and a patterned metal mask layer is prepared on one side surface of the lithium niobate substrate; The side of the lithium niobate substrate with the metal mask layer is selectively ground and etched using an abrasive to form an etched area on the lithium niobate substrate and to remove the metal mask layer. Wherein, the hardness of the metal mask layer is greater than or equal to the hardness of the abrasive, and the hardness of the abrasive is greater than or equal to the hardness of the lithium niobate substrate.

[0029] In one embodiment, providing a lithium niobate substrate includes cleaning the lithium niobate substrate. Exemplarily, the cleaning includes ultrasonic cleaning in acetone, isopropanol and deionized water, followed by nitrogen drying and baking.

[0030] In one embodiment, the material of the metal mask layer is selected from at least one of Cr, W, Mo, and V, preferably Cr. Chromium, tungsten, molybdenum, and vanadium are all refractory metals or transition metals with high hardness, which can effectively resist the impact and wear of abrasives, ensuring that the mask pattern is not destroyed during the grinding and etching process, thereby accurately transferring the pattern to the underlying lithium niobate. This directly guarantees the fidelity and accuracy of the etched pattern.

[0031] In one embodiment, the thickness of the metal mask layer is 100 nm to 3 μm, preferably 200 nm to 1 μm. The lower thickness limit ensures the mask layer is thick enough to continuously and effectively protect the covered lithium niobate region throughout the grinding and etching process (especially in deeper etched areas), preventing etching failure due to premature mask wear. The upper thickness limit avoids excessively thick mask layers that waste material, increase cost and fabrication time. More importantly, in subsequent lift-off processes, excessively thick metal layers can create large steps, potentially leading to irregular pattern edges and increasing the difficulty of mask removal. This range optimizes both mask protection and process simplicity.

[0032] In one embodiment, the abrasive is selected from at least one of SiO2, corundum, CeO2, and ZrO2, preferably SiO2.

[0033] Common abrasive materials with hardness between that of the mask metal and lithium niobate are selected. Among them, SiO2 has moderate hardness, low cost, and wide application; corundum has high hardness, strong cutting ability, and high efficiency; CeO2 can achieve good surface quality; and ZrO2 has high hardness and good toughness. These materials can ensure effective etching of lithium niobate while minimizing damage to the harder metal mask, which is the key material basis for achieving selective etching and provides a variety of cost and efficiency options.

[0034] In one embodiment, the depth of the etched area is 100 nm to 10 μm, preferably 1 μm to 3 μm. This method is applicable not only to surface micromachining but also to the machining of three-dimensional structures with a certain aspect ratio, offering process flexibility and wide applicability.

[0035] In one embodiment, the fabrication of a patterned metal mask layer on one side surface of the lithium niobate substrate includes: A patterned window is formed by homopolymer photolithography on one side surface of the lithium niobate substrate; The material of the metal mask layer is deposited on the surface of the lithium niobate substrate in the graphics window; Remove the photoresist and metal mask layer material from the area outside the graphics window.

[0036] Employing a standard, mature, and reliable lift-off-based solution ensures sharp-edged metal patterns and compatibility with existing processes.

[0037] In one embodiment, during the homogenization photolithography process, the thickness of the photoresist coating is 0.6 μm to 5 μm. This thickness range ensures the feasibility and reliability of the lift-off process; too thin a coating makes lift-off difficult, while too thick a coating affects the pattern resolution. The preferred thickness of the photoresist coating is 1 μm to 2 μm.

[0038] In one embodiment, during the homopolymer photolithography process, the exposure dose is 60 mJ / cm². 2 ~200 mJ / cm 2 This range of exposure doses is an optimized setting designed to ensure steep and dimensionally precise pattern boundaries after photoresist development, thereby achieving the best photolithographic pattern quality and forming a high-quality mask. The preferred exposure dose is 110 mJ / cm². 2 ~130 mJ / cm 2 .

[0039] In one embodiment, the method of depositing the metal mask layer on the surface of the lithium niobate substrate in the graphics window is magnetron sputtering or electron beam evaporation. Electron beam evaporation is preferred, as it facilitates the stripping process.

[0040] In one embodiment, the lithium niobate substrate is a bulk lithium niobate crystal sheet or a lithium niobate thin film.

[0041] In one embodiment, the Mohs hardness of lithium niobate, abrasive, and metal mask layer material is shown in Table 1: Table 1 .

[0043] In one embodiment, a grinding-assisted patterning etching method for lithium niobate, such as... Figure 1 and Figure 2 Specifically, it includes: Step 1: Cleaning. The lithium niobate wafers are ultrasonically cleaned successively in acetone, isopropanol, and deionized water, dried with nitrogen, and baked.

[0044] Step 2: Coating and photolithography. PR photoresist is coated onto the clean surface of a lithium niobate wafer, followed by exposure and development to complete the photolithography process.

[0045] Step 3: Lift-off. For the lithium niobate wafer that has already undergone photolithography, a metal layer is deposited. The metal must be selected with a higher hardness than lithium niobate in order to allow for subsequent selective etching. After the metal layer is deposited, the wafer is placed in an NMP chamber for heating and ultrasonication to complete the lift-off process and achieve a patterned metal mask layer.

[0046] Step 4: Selective etching. The lithium niobate wafer with the patterned metal mask is ground. Taking advantage of the fact that the hardness of the abrasive is higher than that of lithium niobate but lower than that of the metal mask, selective etching of lithium niobate can be performed.

[0047] Step 5: Metal Removal. The metal mask layer is etched using a wet etching process to completely etch the metal layer without etching the lithium niobate, thus achieving the fabrication of a patterned lithium niobate wafer.

[0048] According to another embodiment of this application, the aforementioned grinding-assisted patterning etching method for lithium niobate is applied to the fabrication of optoelectronic devices, MEMS devices, and acoustic filters.

[0049] Example 1: A grinding-assisted patterning etching method for lithium niobate. Step 1: Cleaning. The lithium niobate wafers are ultrasonically cleaned successively in acetone, isopropanol, and deionized water, dried with nitrogen, and baked. Step 2: Coating and Photolithography. A PR photoresist layer with a thickness of 1.5 μm is coated onto the clean lithium niobate wafer surface. Exposure is then performed at a dose of 120 mJ / cm². 2 After development, the photolithography step is completed.

[0050] Step 3: Lift-off. For the lithium niobate wafer that has undergone photolithography, a metal layer is deposited. Methods include magnetron sputtering and electron beam evaporation, with electron beam evaporation being preferred as it facilitates the lift-off process. The metal selected must have a higher hardness than lithium niobate to allow for subsequent selective etching. The metal composition is Cr, and the thickness is 300 nm. After metal layer deposition, the wafer is placed in an NMP (Non-Mechanical Processing) chamber and heated and ultrasonically subjected to complete the lift-off process, achieving a patterned metal mask layer.

[0051] Step 4: Selective Etching. The lithium niobate wafer with the patterned metal mask is polished using SiO2 as the main component of the abrasive. Taking advantage of the abrasive's hardness being higher than lithium niobate but lower than the metal mask, selective etching of the lithium niobate can be performed to a depth of 2µm.

[0052] Step 5: Metal Removal. The Cr mask layer is etched using a wet etching process to completely etch the Cr without etching the lithium niobate, thus achieving the fabrication of a patterned lithium niobate wafer.

[0053] Comparative Example 1: Typical wet etching process in the prior art Taking the typical wet etching process of existing technology as an example, its steps are as follows: Figure 3 As shown, it includes: Step 1: Cleaning. The lithium niobate wafers are ultrasonically cleaned successively in acetone, isopropanol, and deionized water, dried with nitrogen, and baked. Step 2: Photoresist mask preparation. A PR photoresist layer with a thickness of 1.5 μm is coated onto the surface of a clean lithium niobate wafer. Exposure is then performed at a dose of 120 mJ / cm². 2 After development, the photolithography step is completed. A hot plate is then used for hardening and baking, which improves the etching resistance of the subsequent photoresist mask.

[0054] Step 3: Wet Etching. Immerse the lithium niobate wafer with the grown photoresist mask in a mixed solution of HF and HNO3. The volume ratio of HF to HNO3 is 1:3. Immerse the wafer in the acid solution for as long as possible while ensuring the durability of the photoresist mask. Once the photoresist mask begins to peel off, remove the wafer.

[0055] Step 4: Photoresist Removal. Place the wet-etched wafer into a photoresist remover (NMP) and heat it to 70°C. Use ultrasonication to remove the photoresist, exposing the lithium niobate wafer with etched blind vias. This completes the wet etching process for lithium niobate.

[0056] In summary, acid etching in wet etching is isotropic, meaning it etches simultaneously in both vertical and horizontal directions. This leads to severe lateral drilling beneath the photoresist mask. Consequently, the etched pattern size is much larger than the mask pattern size, with rounded sidewalls, extremely poor pattern fidelity, and difficulty in controlling critical dimensions, making it particularly unsuitable for highly integrated micro / nano devices. This application employs abrasive etching, a highly anisotropic physical process. The cutting action of the abrasive particles is primarily perpendicular to the sample surface. Under the protection of the metal mask, etching occurs almost exclusively in the vertical direction, perfectly replicating the pattern from the mask onto lithium niobate. This results in steep sidewalls, precise pattern dimensions, and no lateral drilling. Therefore, the technical solution of this application achieves highly anisotropic etching, obtaining patterns with steep sidewalls and precise dimensions, significantly improving the fidelity and resolution of the etched pattern. Furthermore, grinding is a mechanical material removal process, which is a controllable "cutting" process for brittle crystalline materials like lithium niobate. As long as the parameters are appropriate, it will not cause the large-scale crystal cleavage problems associated with wet etching. In addition, grinding etching rates are generally faster and more stable. More importantly, it saves the "hardening" step and simplifies the subsequent photoresist removal process, which helps improve equipment utilization and production capacity, and reduces overall costs. Traditional wet etching requires an additional "hardening" step to enhance the acid resistance of the photoresist. After etching, photoresist severely damaged by acid may be more difficult to remove. The entire process involves the management of hazardous chemicals and shutdown procedures, resulting in higher overall time and operating costs.

[0057] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for patterned etching of lithium niobate with grinding assistance, characterized in that, include: A lithium niobate substrate is provided, and a patterned metal mask layer is prepared on one side surface of the lithium niobate substrate; The side of the lithium niobate substrate with the metal mask layer is selectively ground and etched using an abrasive to form an etched area on the lithium niobate substrate and to remove the metal mask layer. Wherein, the hardness of the metal mask layer is greater than or equal to the hardness of the abrasive, and the hardness of the abrasive is greater than or equal to the hardness of the lithium niobate substrate.

2. The method for patterned etching of lithium niobate with grinding assistance according to claim 1, characterized in that, The material of the metal mask layer is selected from at least one of Cr, W, Mo, and V.

3. The method for patterned etching of lithium niobate with grinding assistance according to claim 1, characterized in that, The thickness of the metal mask layer is 100nm~3um.

4. The method for patterned etching of lithium niobate with grinding assistance according to claim 1, characterized in that, The abrasive is selected from at least one of SiO2, corundum, CeO2, and ZrO2.

5. The method for patterned etching of lithium niobate with grinding assistance according to claim 1, characterized in that, The depth of the etched area is 100nm~10um.

6. The method for patterned etching of lithium niobate with grinding assistance according to claim 1, characterized in that, The process of fabricating a patterned metal mask layer on one side surface of the lithium niobate substrate includes: A patterned window is formed by homopolymer photolithography on one side surface of the lithium niobate substrate; The material of the metal mask layer is deposited on the surface of the lithium niobate substrate in the graphics window; Remove the photoresist and metal mask layer material from the area outside the graphics window.

7. The method for patterned etching of lithium niobate with grinding assistance according to claim 6, characterized in that, In the homogeneous photolithography process, the thickness of the photoresist coating is 0.6µm to 5µm.

8. The method for patterned etching of lithium niobate with grinding assistance according to claim 6, characterized in that, During the homogeneous photolithography process, the exposure dose is 60 mJ / cm². 2 ~200mJ / cm 2 .

9. The method for patterned etching of lithium niobate with grinding assistance according to claim 6, characterized in that, The method of depositing the metal mask layer on the surface of the lithium niobate substrate in the graphics window is magnetron sputtering or electron beam evaporation.

10. The application of the grinding-assisted patterning etching method for lithium niobate according to any one of claims 1 to 9 in the fabrication of optoelectronic devices, MEMS devices, and acoustic filters.

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