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

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 existing technology cannot protect micro-nano structures. The surface includes: a substrate, a grating structure, and a micro-nano structure; the substrate and the micro-nano structure are an integrated structure, and the grating structure is disposed on the substrate; the grating structure is higher than the micro-nano structure. The present invention realizes the characteristics of anti-damage, anti-pollution, and super-hydrophobicity for various micro-nano structures and solar cells from a microscopic fundamental. The material of the structure in the invention can be, but is not limited to, an oxide layer. When ensuring that the used material has a certain hardness and the optical properties are suitable for the overall structure, the structure can achieve the protection characteristics described in the present invention, and the preparation process of the structure is simple and easy to operate.

Description

Technical Field

[0001] The present invention relates to the field of micro-nano structures and manufacturing, and in particular to an anti-reflective micro-nano structure surface with a protective structure and a preparation method thereof. Background Art

[0002] Since its inception, research in micro-nano manufacturing technology has matured and its application areas have expanded significantly. Today's micro-nano structures, whether in terms of processing, manufacturing, or surface morphology, are firmly at the forefront of the industry. However, with such rapid development, due to their inherent small size, fragility, and susceptibility to contamination, the issue of their protection arises. To enhance the efficiency and extend the lifespan of micro-nano structures, their protection is another key focus of current research.

[0003] Furthermore, due to the impact of sustainable development, solar energy, as a clean and sustainable resource, is now widely used and increasingly mature due to its advantages such as ease of collection, environmental friendliness, and inexhaustible supply. However, the efficiency of solar photovoltaic power generation systems in actual use is far from ideal, with photoelectric conversion efficiencies generally exceeding 20%. Furthermore, these systems are typically located outdoors in open, unobstructed spaces, where fallen leaves and dust accumulate on the surface, further impacting their efficiency. Therefore, the protection of solar cells is also of great importance. Currently, solar cell protection is limited to macroscopic levels. For example, domestic patent No. 202020817659.7 discloses a solar cell panel with a cell protection structure. This structure uses dust shields to shield the photovoltaic panels, preventing damage from wind, sand, and gravel, thereby extending the service life of the solar cells. However, this only provides simple macroscopic protection for the transparent glass on the photovoltaic panel surface. It fails to fundamentally protect the solar cell's power generation components, such as the cells. For example, the optical protective film (EVA) currently used to fix the glass substrate and the power generation body is prone to generating gas when encapsulating exhaust gas between the glass substrate. At this time, tiny dust, sand, water, gasoline and other pollutants will enter, which will seriously affect the overall photoelectric conversion efficiency of the solar cell. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides an anti-reflective micro-nanostructure surface with a protective structure and a preparation method thereof, which solves the problem that the prior art cannot protect the micro-nanostructure.

[0005] The technical solutions adopted by the present invention to solve the technical problems are as follows:

[0006] Anti-reflection micro-nano structure surface with a protective structure, the surface comprising: a substrate, a grating structure and a micro-nano structure; the substrate and the micro-nano structure are an integrated structure, and the grating structure is disposed on the substrate; the grating structure is higher than the micro-nano structure.

[0007] Preferably, the grating structure is a pattern arranged in an orderly manner or in an array.

[0008] Preferably, the pattern is a square or a hexagon.

[0009] Preferably, the material of the substrate and the micro-nano structure is silicon; the material of the grating structure is silicon dioxide.

[0010] Preferably, the height of the grating structure is 100 nm to 1000 nm.

[0011] A method for preparing an anti-reflection micro-nano structure surface with a protective structure, the method comprising the following steps:

[0012] Step 1: Thermally grow a layer of silicon dioxide on the silicon-based surface;

[0013] Step 2: Spin coat photoresist on the silicon dioxide surface;

[0014] Step 3: Prepare a positive photomask based on the grating structure, and use the photomask to expose the photoresist;

[0015] Step 4: Develop and post-bake the exposed photoresist to obtain a photoresist thin film with a pattern;

[0016] Step 5: Perform plasma etching on the silicon-based substrate to obtain the grating structure;

[0017] Step 6: Prepare a polystyrene microsphere photomask based on the micro-nano structure;

[0018] Step 7: Perform plasma etching on the silicon-based substrate provided with the polystyrene microsphere photomask to obtain an anti-reflection micro-nano structure with a protective structure.

[0019] Preferably, in step 7, the etching gas uses CHF3 and SF6, the gas flow ratio is 30:10, and the etching time can be 200 s to 300 s.

[0020] A method for preparing an anti-reflection micro-nano structure surface with a protective structure, wherein steps 3 to 5 are replaced with:

[0021] Step 3: Prepare a negative photomask based on the grating structure, and use the photomask to expose the photoresist;

[0022] Step 4: Develop and post-bake the exposed photoresist to obtain a photoresist thin film with a pattern;

[0023] Step Five: Deposit a metal chromium thin film on the silicon-based surface, and use an organic solution to remove the photoresist on the silicon wafer surface to obtain a structure with a chromium mask;

[0024] Step Six: Perform plasma etching on the silicon-based structure with a chromium mask structure to obtain the mesh grid structure, and remove the metal chromium thin film.

[0025] Preferably, during the etching process in Step Six, the radio frequency power is set to 300 W, the etching gas is CHF3, the gas flow rate is 20 sccm, and the etching time is 300 s - 400 s.

[0026] Preferably, in Step Five, the thickness of the metal chromium thin film is 100 nm - 200 nm.

[0027] The beneficial effects of the present invention are as follows: For the protection of various micro-nano structures and solar cells, the present invention realizes the characteristics of anti-damage, anti-pollution, and superhydrophobicity from the microscopic root. The materials of the structures in the invention can be, but are not limited to, oxide layers. As long as the materials used have a certain hardness and the optical properties are suitable for the overall structure, the structures can all achieve the protection characteristics described in the present invention, and the preparation process of the structure is simple and easy to operate. Brief Description of the Drawings

[0028] Figure 1 Schematic diagram of the surface structure of the anti-reflection micro-nano structure with a protective structure of the present invention.

[0029] Figure 2 The first flow chart of the method for preparing the surface of the anti-reflection micro-nano structure with a protective structure of the present invention.

[0030] Figure 3 The second flow chart of the method for preparing the surface of the anti-reflection micro-nano structure with a protective structure of the present invention.

[0031] Figure 4 The transmittance of the surface structure of the anti-reflection micro-nano structure with a protective structure and the surface structure of the anti-reflection micro-nano structure without a protective structure of the present invention.

[0032] In the figure: 1. Substrate, 2. Mesh grid structure, and 3. Micro-nano structure. Detailed Embodiments

[0033] The following further describes the present invention in detail with reference to the drawings and embodiments.

[0034] As Figure 1As shown in the figure, an anti-reflection micro-nano structure surface with a protective structure, the surface comprising: a substrate 1, a grating structure 2, and a micro-nano structure 3; the substrate 1 and the micro-nano structure 3 are an integrated structure, and the grating structure 2 is disposed on the substrate 1; the grating structure 2 is higher than the micro-nano structure 3. The grating structure 2 is a pattern arranged in an orderly manner or in an array. In this embodiment, the pattern is a square or a hexagon. The materials of the substrate 1 and the micro-nano structure 3 are silicon; the material of the grating structure 2 is silicon dioxide, or other materials with a refractive index match and a certain hardness, such as silicon nitride. The height of the grating structure 2 is 100 nm to 1000 nm.

[0035] As Figure 2 shown, a method for preparing an anti-reflection micro-nano structure surface with a protective structure, the method comprising the following steps:

[0036] Step 1: Thermally grow a layer of silicon dioxide on the surface of the silicon substrate 1, immerse the silicon substrate 1 with the oxide layer in acetone, ethanol, and deionized water for ultrasonic cleaning for 10 min respectively, and then dry it with nitrogen.

[0037] Step 2: Perform a spin-coating process on the surface with silicon dioxide using a spin coater. Select AR-P3740 positive photoresist, and use a multi-step spin coating process during the spin coating process, with the spin coating speed ranging from 1000 rpm to 4000 rpm to ensure uniform coating of the photoresist. Then bake the silicon wafer with the photoresist film at 100 °C for 60 s to completely volatilize the organic solvent in the photoresist.

[0038] Step 3: Prepare a positive mask based on the grating structure 2, and use the mask to expose the photoresist, with an exposure time of about 6 s.

[0039] Step 4: Develop and post-bake the exposed photoresist to obtain a photoresist film with a pattern; prepare a 0.25% NaOH solution as a developer, develop the exposed sample for 5 s, and post-bake it at 90 °C for 60 s to make the properties of the photoresist more stable.

[0040] Step 5: Perform plasma etching on the silicon substrate 1 to obtain the grating structure 2.

[0041] Step 6: After performing a hydrophilic treatment on the surface of the silicon substrate 1 with the grating structure 2, prepare a polystyrene microsphere mask based on the micro-nano structure 3; prepare a piranha solution (the ratio of concentrated sulfuric acid to hydrogen peroxide solution is 7:3), and immerse the silicon substrate 1 with the grating structure 2 in it for more than 12 h for hydrophilic treatment.

[0042] Step 7: Perform plasma etching on the silicon substrate 1 with a polystyrene microsphere mask plate to obtain an antireflective micro-nano structure 3 with a protective structure; first, perform a reduction treatment on the PS (polystyrene) microsphere mask with O2 for 20 - 30 s. The etching gas is CHF3 and SF6, and the gas flow ratio is 30:10. The etching time can be 200 s to 300 s to obtain the surface of the antireflective micro-nano structure with a protective structure.

[0043] As Figure 3 shown, the second method for preparing the surface of the antireflective micro-nano structure with a protective structure includes the following steps:

[0044] Step 1: Thermally grow a layer of silicon dioxide on the surface of the silicon substrate 1. Immerse the silicon substrate 1 with the oxide layer in acetone, ethanol, and secondary deionized water respectively and ultrasonically clean for 10 min, and then dry with nitrogen.

[0045] Step 2: Perform a spin-coating process on the surface with silicon dioxide using a spin coater. Select AR-P3740 positive photoresist, and the spin-coating process adopts a multi-step spin-coating process with the spin speed ranging from 1000 rpm to 4000 rpm to ensure uniform coating of the photoresist. Then pre-bake the silicon wafer with the photoresist film at 100 °C for 60 s to completely volatilize the organic solvent in the photoresist.

[0046] Step 3: Prepare a negative mask plate based on the mesh grid structure 2, and use the mask plate to expose the photoresist for about 6 s.

[0047] Step 4: Develop and post-bake the exposed photoresist to obtain a photoresist film with a pattern; prepare a 0.25% NaOH solution as the developer, develop the exposed sample for 5 s, and post-bake at 90 °C for 60 s to make the properties of the photoresist more stable.

[0048] Step 5: Deposit a metal chromium film on the surface of the silicon substrate 1 with a thickness of 100 nm - 200 nm, and use an organic solution to remove the photoresist on the surface of the silicon substrate 1 to obtain a structure with a chromium mask.

[0049] Step 6: Perform plasma etching on the silicon substrate 1 with a chromium mask structure to obtain the mesh grid structure 2 and remove the metal chromium film; during the etching process, set the RF power to 300 W, use CHF3 as the etching gas with a gas flow of 20 sccm, and the etching time is 300 s - 400 s. Then use a chromium-removing solution to remove the metal chromium on the surface of the structure;

[0050] Step 7: After hydrophilically treating the surface of the silicon substrate 1 with the grid structure 2, prepare a polystyrene microsphere mask based on the micro-nano structure 3; configure a piranha solution (the ratio of concentrated sulfuric acid to hydrogen peroxide solution is 7:3), and immerse the silicon substrate 1 with the grid structure 2 therein for more than 12 h for hydrophilization treatment.

[0051] Step 8: Perform plasma etching on the silicon substrate 1 provided with the polystyrene microsphere mask to obtain an anti-reflection micro-nano structure 3 with a protective structure; first perform a reduction treatment on the PS (polystyrene) microsphere mask using O2 for 20 - 30 s. The etching gas is CHF3 and SF6, and the gas flow ratio is 30:10. The etching time can be 200 s to 300 s to obtain the surface of the anti-reflection micro-nano structure with a protective structure.

[0052] To verify that the microscopic protection structure described in the present invention has little influence on the overall optical performance of the protected structure, specific examples are used for demonstration as follows.

[0053] As Figure 4 shown, it is a comparison of the transmittance of a micro-nano structure with a certain parameter and the transmittance after adding a protection structure. The height of this protection structure is 500 nm, and the duty cycle (i.e., 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 in the wavelength band of 3 μm to 5 μm, the transmittance of the original micro-nano structure 3 is in the range of 99% - 91%. After adding the grid structure 2 with a protection function to the micro-nano structure 3, under the same wavelength condition, the transmittance can still reach 98.5% - 92%, and the influence on the transmittance is less than 1%. Thus, it can be shown that the grid structure 2 has little influence on the overall optical performance of the protected micro-nano structure 3, and in some cases, it can improve its optical performance and has good protection ability.

Claims

1. An anti-reflection micro-nano structure surface with a protective structure, characterized in that, The surface includes: a substrate, a grating structure, and a micro-nano structure; the substrate and the micro-nano structure are an integrated structure, and the grating structure is disposed on the substrate; the grating structure is higher than the micro-nano structure; the materials of the substrate and the micro-nano structure are silicon; the material of the grating structure is silicon dioxide; the height of the grating structure is 100 nm to 1000 nm; The method for preparing the anti-reflection micro-nano structure surface with a protective structure includes the following steps: Step 1: Thermally grow a layer of silicon dioxide on the silicon-based surface; Step 2: Spin-coat photoresist on the silicon dioxide surface; Step 3: Prepare a positive mask based on the grating structure, and use the mask to expose the photoresist; Step 4: Develop and post-bake the exposed photoresist to obtain a photoresist film with a pattern; Step 5: Perform plasma etching on the silicon-based substrate to obtain the grating structure; Step 6: Prepare a polystyrene microsphere mask based on the micro-nano structure; Step 7: Perform plasma etching on the silicon-based substrate provided with the polystyrene microsphere mask to obtain a anti-reflection micro-nano structure with a protective structure.

2. The antireflection micro-nano structure surface with a protective structure according to claim 1, characterized in that, The grating structure is a pattern of ordered arrangement or array.

3. The anti-reflection micro-nano structure surface with a protective structure according to claim 2, characterized in that, The pattern is a square or a hexagon.

4. The anti-reflection micro-nano structure surface with a protective structure according to claim 1, characterized in that, The etching gas used in the plasma etching in Step 7 is CHF3 and SF6, the gas flow ratio is 30:10, and the etching time is 200 s to 300 s.

5. The anti-reflection micro-nano structure surface with a protective structure according to claim 1, characterized in that, Steps 3 to 5 are replaced with: Step 3: Prepare a negative mask based on the grating structure, and use the mask to expose the photoresist; Step 4: Develop and post-bake the exposed photoresist to obtain a photoresist film with a pattern; Step 5: Deposit a metal chromium film on the silicon-based surface, and use an organic solution to remove the photoresist on the silicon wafer surface to obtain a structure with a chromium mask; Step 6: Perform plasma etching on the silicon-based substrate with the chromium mask structure to obtain the grating structure, and remove the metal chromium film.

6. The anti-reflection micro-nano structure surface with a protective structure according to claim 5, characterized in that, During the plasma etching in Step 6, the radio frequency power is set to 300 W, the etching gas used in the plasma etching is CHF3, the gas flow rate is 20 sccm, and the etching time is 300 s - 400 s.

7. The anti-reflection micro-nano structure surface with a protective structure according to claim 5, characterized in that, In Step 5, the thickness of the metal chromium film is 100 - 200 nm.

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