CN114988349A - Anti-reflection micro-nano structure surface with protective structure and preparation method thereof - Google Patents

Abstract

An anti-reflection micro-nano structure surface with a protective structure and a preparation method thereof relate to the field of micro-nano structures and manufacturing, and solve the problem that the micro-nano structures cannot be protected in the prior art. The surface includes: the device comprises a substrate, a grid structure and a micro-nano structure; the substrate and the micro-nano structure are of an integrated structure, and the grid structure is arranged on the substrate; the grid structure is higher than the micro-nano structure. The invention protects various micro-nano structures and solar cells, and fundamentally realizes the characteristics of damage resistance, pollution resistance and super-hydrophobicity from the microscopic view. The material of the structure in the invention can adopt but is not limited to an oxide layer, under the condition that the used material has certain hardness and the optical property is suitable for the whole structure, the structure can realize the protection characteristic of the invention, and the structure has simple preparation flow and easy operation.

Description

Translated fromChinese

带有保护性结构的抗反射微纳结构表面及其制备方法Anti-reflection micro-nano structure surface with protective structure and preparation method thereof

技术领域technical field

本发明涉及微纳结构及制造领域，具体涉及一种带有保护性结构的抗反射微纳结构表面及其制备方法。The invention relates to the field of micro-nano structures and manufacturing, in particular to an anti-reflection micro-nano structure surface with a protective structure and a preparation method thereof.

背景技术Background technique

微纳制造技术的研究从其诞生之初到如今发展日益成熟，其应用领域也得到了很大拓展。如今的微纳结构无论是从加工制造还是表面形貌等方面考察，在很大程度上都能够牢据行业的尖端位置。但在微纳结构发展如此迅猛的形势下，由于微纳结构本身具有的结构小、易损伤以及易污染等特点，随之而来的是对其的保护问题。为增强微纳结构使用效率以及延长其使用寿命，针对微纳结构的保护是目前对于微纳结构发展关注的另一重点。The research of micro-nano manufacturing technology has developed more and more mature from the beginning of its birth to now, and its application field has also been greatly expanded. Today's micro-nano structures can be firmly positioned at the forefront of the industry to a large extent, no matter from the aspects of processing and manufacturing or surface morphology. However, with the rapid development of the micro-nano structure, due to the small structure, easy damage and easy pollution of the micro-nano structure itself, there is the problem of its protection. In order to enhance the use efficiency of the micro-nano structure and prolong its service life, the protection of the micro-nano structure is another focus of the current development of the micro-nano structure.

除此之外，由于可持续发展的影响，目前太阳能作为一种可清洁和可持续发展的资源因便于采集、对环境无污染、用之不竭等优点受到了人们的广泛应用且日益发展成熟。然而太阳能的光伏发电系统在实际使用中的效率都不理想，光电转换效率一般都达不到20％。更不论其工作场所通常都设置在开阔空旷、无遮挡的室外，更会有落叶灰尘等完全堆积在表面对其使用效率产生进一步影响。因此对于太阳能电池的保护同样受到人们的重视。目前对于太阳能电池的保护只停留在宏观状态，例如国内第202020817659.7专利公开了一种带有电池保护结构的太阳能电池面板，通过挡尘布对光伏板组的遮挡来防止风沙石子对光伏面板造成的损伤，提高太阳能电池的使用寿命。但实际上只是在宏观上对光伏电板表面的透明玻璃进行简单的防护。而对于太阳能电池的发电主体，如电池片等不能从根本上进行保护。比如目前用来固定玻璃基板与发电主体的光学保护膜(EVA)，其在与玻璃基板之间封装排气时很容易产生气体，此时会有微小的灰尘风沙或水汽油污进入，如此将严重影响太阳能电池整体光电转换效率。In addition, due to the impact of sustainable development, solar energy, as a clean and sustainable resource, has been widely used and matured due to its advantages of easy collection, no pollution to the environment, and inexhaustible use. . However, the efficiency of solar photovoltaic power generation systems in practical use is not ideal, and the photoelectric conversion efficiency is generally less than 20%. Not to mention that the workplace is usually set in an open, open and unobstructed outdoor area, and there will be fallen leaves and dust completely accumulated on the surface, which will further affect its use efficiency. Therefore, the protection of solar cells is also valued by people. At present, the protection of solar cells only stays in the macroscopic state. For example, the domestic patent No. 202020817659.7 discloses a solar cell panel with a battery protection structure. The photovoltaic panel group is shielded by a dust cloth to prevent wind, sand and stones from causing damage to the photovoltaic panel. damage and increase the service life of solar cells. But in fact, it is only a simple protection of the transparent glass on the surface of the photovoltaic panel at the macro level. However, the main power generation of solar cells, such as cells, cannot be fundamentally protected. For example, the optical protective film (EVA) currently used to fix the glass substrate and the main body of the power generation, it is easy to generate gas when the exhaust is encapsulated between the glass substrate and the glass substrate. It affects the overall photoelectric conversion efficiency of solar cells.

发明内容SUMMARY OF THE INVENTION

为了解决现有技术中存在的问题，本发明提供了一种带有保护性结构的抗反射微纳结构表面及其制备方法，解决了现有技术对微纳结构不能得到保护的问题。In order to solve the problems existing in the prior art, the present invention provides an anti-reflection micro-nano structure surface with a protective structure and a preparation method thereof, which solves the problem that the prior art cannot protect the micro-nano structure.

本发明解决技术问题所采用的技术方案如下：The technical scheme adopted by the present invention to solve the technical problem is as follows:

带有保护性结构的抗反射微纳结构表面，该表面包括：基底、网栅结构和微纳结构；所述基底与微纳结构为一体化结构，网栅结构设置在所述基底上；所述网栅结构高于所述微纳结构。An anti-reflection micro-nano structure surface with a protective structure, the surface includes: a substrate, a grid structure and a micro-nano structure; the substrate and the micro-nano structure are an integrated structure, and the grid structure is arranged on the substrate; The grid structure is higher than the micro-nano structure.

优选的，所述网栅结构为有序排布或阵列的图形。Preferably, the grid structure is an orderly arrangement or an array pattern.

优选的，所述图形为正方形或者六边形。Preferably, the figure is a square or a hexagon.

优选的，所述基底与微纳结构的材料为硅；所述网栅结构的材料为二氧化硅。Preferably, the material of the substrate and the micro-nano structure is silicon; the material of the grid structure is silicon dioxide.

优选的，所述网栅结构的高度为100nm～1000nm。Preferably, the height of the grid structure is 100 nm˜1000 nm.

制备带有保护性结构的抗反射微纳结构表面的方法，该方法包括如下步骤：A method for preparing an anti-reflection micro-nano structure surface with a protective structure, the method comprising the steps of:

步骤一：在硅基表面热生长一层二氧化硅；Step 1: Thermally grow a layer of silicon dioxide on the surface of the silicon substrate;

步骤二：在所述二氧化硅表面匀光刻胶；Step 2: uniform photoresist on the silicon dioxide surface;

步骤三：基于所述网栅结构制备阳掩膜版，利用所述掩膜版对光刻胶进行曝光；Step 3: preparing a positive mask based on the grid structure, and exposing the photoresist by using the mask;

步骤四：对曝光后的光刻胶显影和后烘，得到带有图案的光刻胶薄膜；Step 4: developing and post-baking the exposed photoresist to obtain a patterned photoresist film;

步骤五：对所述硅基进行等离子刻蚀，得到所述网栅结构；Step 5: performing plasma etching on the silicon base to obtain the grid structure;

步骤六：基于所述微纳结构制备聚苯乙烯微球掩膜版；Step 6: preparing a polystyrene microsphere mask based on the micro-nano structure;

步骤七：对设有聚苯乙烯微球掩膜版的硅基进行等离子刻蚀，得到带有保护性结构的抗反射微纳结构。Step 7: performing plasma etching on the silicon substrate provided with the polystyrene microsphere mask to obtain an anti-reflection micro-nano structure with a protective structure.

优选的，步骤七所述刻蚀气体采用CHF₃与SF₆，气体流量比为30：10，刻蚀时间可在200s～300s。Preferably, the etching gas in step 7 is CHF₃ and SF₆ , the gas flow ratio is 30:10, and the etching time can be between 200s and 300s.

制备带有保护性结构的抗反射微纳结构表面的方法，所述步骤三至步骤五替换成：A method for preparing an anti-reflection micro-nano structure surface with a protective structure, the steps three to five are replaced with:

步骤三：基于所述网栅结构制备阴掩膜版，利用所述掩膜版对光刻胶进行曝光；Step 3: preparing a negative mask based on the grid structure, and exposing the photoresist by using the mask;

步骤四：对曝光后的光刻胶显影和后烘，得到带有图案的光刻胶薄膜；Step 4: developing and post-baking the exposed photoresist to obtain a patterned photoresist film;

步骤五：在所述硅基表面镀金属铬薄膜，使用有机溶液去除硅片表面的光刻胶，得到带有铬掩模的结构；Step 5: plating a metal chromium film on the surface of the silicon substrate, and using an organic solution to remove the photoresist on the surface of the silicon wafer to obtain a structure with a chromium mask;

步骤六：对带有铬掩膜结构的硅基进行等离子刻蚀，得到所述网栅结构，去除金属铬薄膜。Step 6: perform plasma etching on the silicon substrate with the chrome mask structure to obtain the grid structure, and remove the metal chrome film.

优选的，步骤六刻蚀过程中射频功率设定为300W，刻蚀气体采用CHF₃，气体流量为20sccm，刻蚀时间300s-400s。Preferably, in the etching process of step 6, the radio frequency power is set to 300W, the etching gas is CHF₃ , the gas flow rate is 20 sccm, and the etching time is 300s-400s.

优选的，所述步骤五中，金属铬薄膜的厚度为100nm～200nm。Preferably, in the fifth step, the thickness of the metal chromium thin film is 100 nm˜200 nm.

本发明的有益效果是：本发明对于各种微纳结构以及太阳能电池的保护，是从微观根本上实现抗损伤、抗污染以及超疏水性的特性。发明中结构的材料可以采用但不限于氧化层，在确保所用的材料具有一定硬度且光学性能适用于整体结构的情况下，结构均可以实现本发明所述的保护特性，且该结构制备流程简单，易于操作。The beneficial effects of the present invention are: the protection of various micro-nano structures and solar cells of the present invention is to fundamentally realize the characteristics of anti-damage, anti-pollution and super-hydrophobicity from a microscopic level. The material of the structure in the invention can be, but not limited to, an oxide layer. Under the condition that the material used has a certain hardness and the optical properties are suitable for the overall structure, the structure can achieve the protection properties described in the present invention, and the preparation process of the structure is simple. , easy to operate.

附图说明Description of drawings

图1本发明带有保护性结构的抗反射微纳结构表面结构示意图。1 is a schematic diagram of the surface structure of the anti-reflection micro-nano structure with a protective structure of the present invention.

图2本发明制备带有保护性结构的抗反射微纳结构表面的方法的第一流程图。FIG. 2 is a first flow chart of the method for preparing an anti-reflection micro-nano structure surface with a protective structure according to the present invention.

图3本发明制备带有保护性结构的抗反射微纳结构表面的方法的第二流程图。FIG. 3 is a second flow chart of the method for preparing an anti-reflection micro-nano structure surface with a protective structure according to the present invention.

图4本发明带有保护性结构的抗反射微纳结构表面结构与没有保护性结构的抗反射微纳结构表面结构的透过率。4 is the transmittance of the anti-reflection micro-nano structure surface structure with protective structure and the anti-reflection micro-nano structure surface structure without protective structure of the present invention.

图中：1、基底，2、网栅结构和3、微纳结构。In the figure: 1. Substrate, 2. Grid structure and 3. Micro-nano structure.

具体实施方式Detailed ways

下面结合附图和实施例对本发明做进一步详细说明。The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

如图1所示，带有保护性结构的抗反射微纳结构表面，该表面包括：基底1、网栅结构2和微纳结构3；所述基底1与微纳结构3为一体化结构，网栅结构2设置在所述基底1上；所述网栅结构2高于所述微纳结构3。所述网栅结构2为有序排布或阵列的图形。本实施例中，所述图形为正方形或者六边形。所述基底1与微纳结构3的材料为硅；所述网栅结构2的材料为二氧化硅，或其他折射率匹配且具有一定硬度的材料，比如氮化硅。所述网栅结构2的高度为100nm～1000nm。As shown in Figure 1, the anti-reflection micro-nano structure surface with protective structure includes:substrate 1, grid structure 2 andmicro-nano structure 3; thesubstrate 1 andmicro-nano structure 3 are integrated structures, The grid structure 2 is arranged on thesubstrate 1 ; the grid structure 2 is higher than themicro-nano structure 3 . The grid structure 2 is an orderly arrangement or an array pattern. In this embodiment, the figure is a square or a hexagon. The material of thesubstrate 1 and themicro-nano structure 3 is silicon; the material of the grid structure 2 is silicon dioxide, or other materials with matching refractive index and certain hardness, such as silicon nitride. The height of the grid structure 2 is 100 nm˜1000 nm.

如图2所示，制备带有保护性结构的抗反射微纳结构表面的方法，该方法包括如下步骤：As shown in Figure 2, the method for preparing an anti-reflection micro-nano structure surface with a protective structure includes the following steps:

步骤一：在硅基底1表面热生长一层二氧化硅，对带有氧化层的硅基底1分别浸入丙酮、乙醇和二次去离子水中超声10min进行清洗，然后使用氮气吹干。Step 1: Thermally grow a layer of silicon dioxide on the surface of thesilicon substrate 1, immerse thesilicon substrate 1 with the oxide layer in acetone, ethanol and secondary deionized water for ultrasonic cleaning for 10 minutes, and then dry it with nitrogen.

步骤二：利用匀胶机在带有二氧化硅表面进行匀胶工艺。选用AR-P3740正胶，匀胶过程采用多步旋涂工艺，旋涂速度从1000rpm到4000rpm，以确保光刻胶涂布均匀。之后将带有光刻胶薄膜的硅片在100℃下前烘60s，使光刻胶中的有机溶剂挥发彻底。Step 2: Use a glue gluer to carry out glue glue process on the surface with silica. The AR-P3740 positive adhesive is selected, and the multi-step spin coating process is used in the adhesive mixing process, and the spin coating speed is from 1000rpm to 4000rpm to ensure uniform photoresist coating. After that, the silicon wafer with the photoresist film was pre-baked at 100° C. for 60 s, so that the organic solvent in the photoresist was completely volatilized.

步骤三：基于所述网栅结构2制备阳掩膜版，利用所述掩膜版对光刻胶进行曝光，曝光时间约6s。Step 3: Prepare a positive mask based on the grid structure 2, and use the mask to expose the photoresist, and the exposure time is about 6s.

步骤四：对曝光后的光刻胶显影和后烘，得到带有图案的光刻胶薄膜；配置浓度为0.25％的NaOH溶液作为显影剂，对曝光后的样品显影5s，并在90℃下后烘60s，使光刻胶的性质更为稳定。Step 4: Develop and post-bake the exposed photoresist to obtain a patterned photoresist film; configure a 0.25% NaOH solution as a developer, develop the exposed sample for 5s, and heat it at 90°C Post-bake 60s to make the properties of the photoresist more stable.

步骤五：对所述硅基底1进行等离子刻蚀，得到所述网栅结构2。Step 5: performing plasma etching on thesilicon substrate 1 to obtain the grid structure 2 .

步骤六：在带有网栅结构2的硅基底1表面进行亲水处理后，基于所述微纳结构3制备聚苯乙烯微球掩膜版；配置食人鱼溶液(浓硫酸与过氧化氢溶液配比为7：3)，将带有网栅结构2的硅基底1浸入其中12h以上进行亲水处理。Step 6: After performing hydrophilic treatment on the surface of thesilicon substrate 1 with the grid structure 2, prepare a polystyrene microsphere mask based on themicro-nano structure 3; configure a piranha solution (concentrated sulfuric acid and hydrogen peroxide solution) The ratio is 7:3), and thesilicon substrate 1 with the grid structure 2 is immersed in it for more than 12 hours for hydrophilic treatment.

步骤七：对设有聚苯乙烯微球掩膜版的硅基底1进行等离子刻蚀，得到带有保护性结构的抗反射微纳结构3；首先对PS(聚苯乙烯)微球掩模使用O₂进行缩减处理，时间为20-30s所述刻蚀气体采用CHF₃与SF₆，气体流量比为30：10，刻蚀时间可在200s～300s，得到带有保护性结构的抗反射微纳结构表面。Step 7: perform plasma etching on thesilicon substrate 1 provided with the polystyrene microsphere mask to obtain an anti-reflectionmicro-nano structure 3 with a protective structure; first, use the PS (polystyrene) microsphere mask O₂ is reduced, the time is 20-30s, the etching gas is CHF₃ and SF₆ , the gas flow ratio is 30:10, the etching time can be 200s-300s, and the anti-reflection microstructure with protective structure is obtained. nanostructured surface.

如图3所示，制备带有保护性结构的抗反射微纳结构表面的第二种方法，该方法包括如下步骤：As shown in Figure 3, the second method for preparing an anti-reflection micro-nano-structured surface with a protective structure includes the following steps:

步骤一：在硅基底1表面热生长一层二氧化硅，对带有氧化层的硅基底1分别浸入丙酮、乙醇和二次去离子水中超声10min进行清洗，然后使用氮气吹干。Step 1: Thermally grow a layer of silicon dioxide on the surface of thesilicon substrate 1, immerse thesilicon substrate 1 with the oxide layer in acetone, ethanol and secondary deionized water for ultrasonic cleaning for 10 minutes, and then dry it with nitrogen.

步骤二：利用匀胶机在带有二氧化硅表面进行匀胶工艺。选用AR-P3740正胶，匀胶过程采用多步旋涂工艺，旋涂速度从1000rpm到4000rpm，以确保光刻胶涂布均匀。之后将带有光刻胶薄膜的硅片在100℃下前烘60s，使光刻胶中的有机溶剂挥发彻底。Step 2: Use a glue gluer to carry out glue glue process on the surface with silica. The AR-P3740 positive adhesive is selected, and the multi-step spin coating process is used in the adhesive mixing process, and the spin coating speed is from 1000rpm to 4000rpm to ensure uniform photoresist coating. After that, the silicon wafer with the photoresist film was pre-baked at 100° C. for 60 s, so that the organic solvent in the photoresist was completely volatilized.

步骤三：基于所述网栅结构2制备阴掩膜版，利用所述掩膜版对光刻胶进行曝光，曝光时间约6s。Step 3: prepare a negative mask based on the grid structure 2, and use the mask to expose the photoresist, and the exposure time is about 6s.

步骤四：对曝光后的光刻胶显影和后烘，得到带有图案的光刻胶薄膜；配置浓度为0.25％的NaOH溶液作为显影剂，对曝光后的样品显影5s，并在90℃下后烘60s，使光刻胶的性质更为稳定。Step 4: Develop and post-bake the exposed photoresist to obtain a patterned photoresist film; configure a 0.25% NaOH solution as a developer, develop the exposed sample for 5s, and heat it at 90°C Post-bake 60s to make the properties of the photoresist more stable.

步骤五：在所述硅基底1表面镀金属铬薄膜，薄膜的厚度为100nm～200nm，使用有机溶液去除硅基底1表面的光刻胶，得到带有铬掩模的结构。Step 5: plating a metal chromium film on the surface of thesilicon substrate 1 with a thickness of 100 nm to 200 nm, using an organic solution to remove the photoresist on the surface of thesilicon substrate 1 to obtain a structure with a chromium mask.

步骤六：对带有铬掩膜结构的硅基底1进行等离子刻蚀，得到所述网栅结构2，去除金属铬薄膜；刻蚀过程中射频功率设定为300W，刻蚀气体采用CHF₃，气体流量为20sccm，刻蚀时间300s-400s，之后用去铬液去除结构表面金属铬；Step 6: perform plasma etching on thesilicon substrate 1 with the chrome mask structure to obtain the grid structure 2, and remove the metal chrome film; during the etching process, the radio frequency power is set to 300W, and the etching gas is CHF₃ , The gas flow is 20sccm, the etching time is 300s-400s, and then the chromium removal solution is used to remove the metal chromium on the surface of the structure;

步骤七：在带有网栅结构2的硅基底1表面进行亲水处理后，基于所述微纳结构3制备聚苯乙烯微球掩膜版；配置食人鱼溶液(浓硫酸与过氧化氢溶液配比为7：3)，将带有网栅结构2的硅基底1浸入其中12h以上进行亲水处理。Step 7: After hydrophilic treatment is performed on the surface of thesilicon substrate 1 with the grid structure 2, a polystyrene microsphere mask is prepared based on themicro-nano structure 3; The ratio is 7:3), and thesilicon substrate 1 with the grid structure 2 is immersed in it for more than 12 hours for hydrophilic treatment.

步骤八：对设有苯乙烯微球掩膜版的硅基底1进行等离子刻蚀，得到带有保护性结构的抗反射微纳结构3；首先对PS(聚苯乙烯)微球掩模使用O₂进行缩减处理，时间为20-30s所述刻蚀气体采用CHF₃与SF₆，气体流量比为30：10，刻蚀时间可在200s～300s，得到带有保护性结构的抗反射微纳结构表面。Step 8: Plasma etching is performed on thesilicon substrate 1 provided with the styrene microsphere mask to obtain an anti-reflectionmicro-nano structure 3 with a protective structure; first, use O for the PS (polystyrene) microsphere mask_2. Carry out reduction treatment, the time is 20-30s, the etching gas adopts CHF₃ and SF₆ , the gas flow ratio is 30:10, the etching time can be 200s-300s, and the anti-reflection micro-nano with protective structure is obtained. structured surface.

为验证本发明所述的微观保护结构对被保护结构整体光学性能影响很小，特用如下具体实例进行证明。In order to verify that the microscopic protective structure described in the present invention has little effect on the overall optical performance of the protected structure, the following specific examples are used to prove it.

如图4所示，为某个参数微纳结构的透过率与其加了保护结构后的透过率比较。该保护结构高度为500nm，占空比(即保护结构宽度与保护范围之比)为0.5：25。从图中可以看出，在波段3μm～5μm下，原始的微纳结构3透过率在99％-91％范围内。在加了具有保护功能的网栅结构2后的微纳结构3在同一波长条件下，透过率仍然能够达到98.5％-92％，透过率影响不足1％。由此可以说明，该网栅结构2对被保护微纳结构3整体的光学性能影响不大，且在某些情况下能够提高其光学性能并具有良好的保护能力。As shown in Figure 4, the transmittance of the micro-nano structure for a certain parameter is compared with the transmittance after adding the protective structure. The height of the protection structure is 500 nm, and the duty ratio (ie the ratio of the width of the protection structure to the protection range) is 0.5:25. It can be seen from the figure that the transmittance of the originalmicro-nano structure 3 is in the range of 99%-91% in the wavelength range of 3 μm to 5 μm. Under the condition of the same wavelength, the transmittance of themicro-nano structure 3 after adding the grid structure 2 with protection function can still reach 98.5%-92%, and the transmittance influence is less than 1%. It can be shown that the grid structure 2 has little effect on the overall optical performance of the protectedmicro-nano structure 3, and can improve its optical performance and have good protection ability in some cases.

Claims (10)

1. An anti-reflective micro-nano structure surface with a protective structure, the surface comprising: the device comprises a substrate, a grid structure and a micro-nano structure; the substrate and the micro-nano structure are of an integrated structure, and the grid structure is arranged on the substrate; the grid structure is higher than the micro-nano structure.

2. The anti-reflective micro-nano structured surface with a protective structure according to claim 1, wherein the grid structure is a pattern of ordered arrangement or array.

3. The anti-reflective micro-nano structured surface with protective structures according to claim 1, wherein the pattern is square or hexagonal.

4. The anti-reflective micro-nano structure surface with a protective structure according to claim 1, wherein the substrate and the micro-nano structure are made of silicon; the material of the mesh structure is silicon dioxide.

5. The anti-reflective micro-nano structured surface with a protective structure according to claim 1, wherein the height of the grid structure is 100nm to 1000 nm.

6. Method for preparing the anti-reflective micro-nano structured surface with protective structure according to any of claims 1 to 5, characterized in that the method comprises the following steps:

the method comprises the following steps: thermally growing a layer of silicon dioxide on the surface of the silicon substrate;

step two: uniformly coating photoresist on the surface of the silicon dioxide;

step three: preparing a positive mask plate based on the grid structure, and exposing photoresist by using the mask plate;

step four: developing and post-baking the exposed photoresist to obtain a photoresist film with a pattern;

step five: carrying out plasma etching on the silicon substrate to obtain the grid structure;

step six: preparing a polystyrene microsphere mask based on the micro-nano structure;

step seven: and carrying out plasma etching on the silicon substrate provided with the polystyrene microsphere mask to obtain the anti-reflection micro-nano structure with the protective structure.

7. The method of claim 6, wherein CHF is used as the etching gas in the seventh step₃ And SF₆ The gas flow ratio is 30: 10, the etching time can be 200 s-300 s.

8. The method of claim 6, wherein steps three through five are replaced with:

step three: preparing a negative mask plate based on the grid structure, and exposing photoresist by using the mask plate;

step four: developing and post-baking the exposed photoresist to obtain a photoresist film with a pattern;

step five: plating a metal chromium film on the surface of the silicon substrate, and removing photoresist on the surface of the silicon wafer by using an organic solution to obtain a structure with a chromium mask;

step six: and carrying out plasma etching on the silicon substrate with the chromium mask structure to obtain the grid structure, and removing the metal chromium film.

9. The method of claim 8, wherein the RF power is set to 300W in the sixth etching process, and CHF is used as the etching gas₃ The gas flow is 20sccm, and the etching time is 300s-400 s.

10. The method of claim 8, wherein in the fifth step, the thickness of the metal chromium film is 100 to 200 nm.

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