Antireflection film, preparation method thereof and optical device

Abstract

The invention discloses an antireflection film, a preparation method thereof and an optical device, and relates to the technical field of optics, the method comprises the steps that a composite material film layer is deposited on a substrate, the composite material film layer comprises a first material and a second material, and the etching rate of the first material is different from that of the second material during wet etching or dry etching; performing wet etching or dry etching on the composite material film layer to obtain a porous film layer; and sequentially carrying out cleaning treatment and drying treatment on the porous membrane layer. According to the anti-reflection film, the preparation method thereof and the optical device, the anti-reflection film of a porous structure is prepared by combining a coating technology commonly used in the industry and laboratories with a wet or dry etching method, equipment hardware does not need to be transformed, and the anti-reflection film is efficient and low in cost.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to an anti-reflection film and a preparation method thereof, and an optical device. Background Art

[0002] Anti-reflection coatings (ARC) are widely used in fields such as eyewear, camera lenses, solar cells, and aerospace components by reducing surface light reflectivity, thereby reducing light energy loss and improving light transmittance, image clarity, and signal-to-noise ratio. Currently, the main technical difficulty in preparing ARC lies in how to produce an ARC with high anti-reflection effect while ensuring reasonable cost (e.g., thickness, chemical composition, equipment, and process selection).

[0003] Common methods for coating anti-reflection films include: 1) surface texturing by wet or dry etching of a single material. Wet etching of a single material has poor directionality, which will reduce the anti-reflection effect. Dry etching of a single material has high equipment cost, requires coating of a mask, and uses a photolithography process, which has many preparation process steps; 2) laser surface treatment of the substrate to achieve the texturing effect. This method has high requirements on the thermal stability of the substrate and is prone to local burns or deformation; 3) Changing the surface morphology of the thin film by adjusting the coating process parameters. There are many preparation process steps and high costs; 4) Design and vacuum coating of multi-layer films. This method requires that the interface stability between film layers and the optical properties between film layers need to match each other. Summary of the Invention

[0004] The purpose of the present invention is to provide an anti-reflection film and its preparation method, and an optical device. The anti-reflection film with a porous structure is prepared by combining the coating technology commonly used in industry and laboratories with a wet or dry etching method. There is no need to modify the equipment hardware, and it is efficient and low-cost.

[0005] The embodiment of the present invention is achieved as follows:

[0006] According to a first aspect of an embodiment of the present invention, a method for preparing an anti-reflection film is provided, the method comprising:

[0007] Depositing a composite material film layer on a substrate, wherein the composite material film layer comprises a first material and a second material, and the first material and the second material have different etching rates during wet etching or dry etching;

[0008] Wet etching or dry etching the composite material film layer to obtain a porous film layer;

[0009] The porous membrane layer is sequentially cleaned and dried.

[0010] As an practicable manner, the step of depositing a composite material film layer on a substrate includes:

[0011] The composite film layer is deposited on the substrate by physical vapor deposition, chemical vapor deposition or atomic layer deposition.

[0012] As an practicable manner, the wet etching or dry etching of the composite material film layer to obtain the porous film layer includes:

[0013] The composite material membrane layer is wet-etched by an etching solution to obtain a porous membrane layer, wherein the etching temperature is between 20 and 150°C.

[0014] As an practicable manner, the etching solution is oxalic acid, hydrofluoric acid, sodium carbonate, phosphoric acid, nitric acid or sodium hydride.

[0015] As an practicable manner, the wet etching or dry etching of the composite material film layer to obtain the porous film layer includes:

[0016] The composite material membrane layer is dry-etched by etching gas to obtain a porous membrane layer, wherein the etching temperature is between 20 and 150°C.

[0017] As an practicable manner, the etching gas is at least one of argon, oxygen, trifluoromethane, carbon tetrafluoride, sulfur hexafluoride and octafluorocyclobutane.

[0018] As an practicable manner, the sequentially cleaning and drying of the porous membrane layer includes:

[0019] Cleaning the porous membrane layer by an ultrasonic cleaning machine;

[0020] The porous membrane layer is dried by a centrifuge or a drying machine, wherein the drying temperature of the drying machine is between 50 and 120°C.

[0021] As an practicable manner, the thickness of the composite material film layer is between 10 and 1000 nm.

[0022] As an practicable manner, the substrate is glass, crystalline silicon, sapphire or plastic.

[0023] As an practicable manner, the first material and the second material are silicon dioxide, aluminum oxide, titanium dioxide, hafnium dioxide, tantalum pentoxide, niobium pentoxide or zirconium oxide.

[0024] According to a second aspect of the embodiments of the present invention, an anti-reflection film is provided, which is prepared using the above-mentioned method for preparing the anti-reflection film.

[0025] According to a third aspect of the embodiments of the present invention, an optical device is provided, comprising the above-mentioned anti-reflection film.

[0026] The beneficial effects of the embodiments of the present invention include:

[0027] The method for preparing the anti-reflection film includes: depositing a composite film layer on a substrate, wherein the composite film layer includes a first material and a second material, and the first material and the second material have different etching rates during wet etching or dry etching; wet etching or dry etching the composite film layer to obtain a porous film layer; and sequentially cleaning and drying the porous film layer. Compared with the prior art, the method for preparing the anti-reflection film provided by the present application utilizes the difference in etching rates and does not require the use of a photomask. It directly forms an anti-reflection film with a porous structure by selectively removing different materials, which can allow light to be captured and transmitted by the velvet surface multiple times, thereby greatly reducing the reflectivity. At the same time, the method for preparing the anti-reflection film provided by the present application does not require expensive nano-processing equipment (such as an electron beam lithography machine). It can be achieved by combining the coating technology commonly used in industry and laboratories with wet or dry etching methods, and is suitable for large-scale industrial production. In addition, the preparation method of the anti-reflection film provided in this application is more flexible in material selection. The material combination can be adjusted according to substrate compatibility (such as flexible substrates requiring low-temperature processes) and cost requirements (such as replacing precious metals with polymers) to reduce preparation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 A flow chart of a method for preparing an anti-reflection film according to an embodiment of the present invention;

[0030] Figure 2 One of the state diagrams of the method for preparing an anti-reflection film provided in an embodiment of the present invention;

[0031] Figure 3 The second state diagram of the method for preparing the anti-reflection film provided by an embodiment of the present invention;

[0032] Figure 4 A graph showing transmittance and reflectance of a composite material film layer provided in an embodiment of the present invention;

[0033] Figure 5 This is a graph showing the transmittance and reflectance of the porous membrane layer provided in an embodiment of the present invention.

[0034] Icon: 10-substrate; 20-composite material membrane layer; 30-first material; 40-second material; 50-porous membrane layer. DETAILED DESCRIPTION

[0035] The embodiments set forth below represent the information necessary to enable those skilled in the art to practice the embodiments and illustrate the best mode for practicing the embodiments. After reading the following description with reference to the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure and will recognize applications of these concepts not specifically set forth herein. It should be understood that these concepts and applications fall within the scope of the present disclosure and the appended claims.

[0036] It should be understood that although the terms first, second, etc. can be used to describe various elements in this article, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of this disclosure, a first element can be referred to as a second element, and similarly, a second element can be referred to as a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0037] It should be understood that when an element (such as a layer, region or substrate) is referred to as being “on” or “extending onto” another element, it can be directly on or directly extend onto the other element, or intervening elements may be present. Similarly, it should be understood that when an element (such as a layer, region or substrate) is referred to as being “over” or “extending onto” another element, it can be directly on or extend directly over the other element, or intervening elements may be present.

[0038] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" are intended to include the plural forms as well. It should also be understood that when used herein, the term "comprising" indicates the presence of the recited features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0039] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. It should also be understood that the terms used herein should be interpreted as having the same meaning as in the context of this specification and the relevant art, and should not be interpreted in an idealized or overly formal sense, unless otherwise explicitly defined herein.

[0040] There are many existing methods for coating anti-reflection films. For example, surface texturing can be achieved by wet or dry etching of a single material. Among them, wet etching of a single material for texturing has poor directionality, which will reduce the anti-reflection effect. The equipment cost of dry etching of a single material for texturing is high, and it is necessary to apply a mask and use a photolithography process, which has the problem of many preparation process steps. Alternatively, the surface of the substrate can be treated by laser to achieve the texturing effect. This method has high requirements on the thermal stability of the substrate and is prone to local burns or deformation. Alternatively, the surface morphology of the thin film can be changed by adjusting the coating process parameters. There are many preparation process steps and high costs. Alternatively, multi-layer film design and vacuum coating can be used. This method requires that the interface stability between film layers and the optical properties between film layers need to match each other.

[0041] To solve the above problems, please refer to Figures 1 to 3 The present application provides an anti-reflection film, a preparation method thereof, and an optical device. The anti-reflection film with a porous structure is prepared by combining the coating technology commonly used in industry and laboratories with a wet or dry etching method. There is no need to modify the equipment hardware, and it is efficient and low-cost.

[0042] Specifically, if Figures 1 to 3 As shown, in a first aspect of an embodiment of the present application, a method for preparing an anti-reflection film is provided, the method comprising:

[0043] S1: depositing a composite material film layer 20 on a substrate 10, wherein the composite material film layer 20 includes a first material 30 and a second material 40, and the first material 30 and the second material 40 have different etching rates during wet etching or dry etching;

[0044] It should be noted that if Figure 1 and Figure 2 As shown, first, a substrate 10 is provided, which is used as the material basis for thin film deposition. The surface of the substrate 10 needs to be smooth, dry, and clean, so that thin film deposition can be performed on the surface of the substrate 10 in subsequent steps. Secondly, a composite material film layer 20 composed of a first material 30 and a second material 40 is uniformly deposited on the surface of the substrate 10. The two materials exist in a mixed state (uniformly dispersed at the nanometer level). The core characteristic of the two materials is that there is a significant difference in their etching rates in the wet etching or dry etching process, which lays the foundation for the subsequent precise control of the structure of the composite material film layer 20.

[0045] S2: wet etching or dry etching the composite material membrane layer 20 to obtain a porous membrane layer 50;

[0046] S3: The porous membrane layer 50 is sequentially cleaned and dried.

[0047] It should be noted that if Figure 1 and Figure 3 As shown, again, by utilizing the difference in etching rates between the first material 30 and the second material 40, the etching material with a faster etching rate can be selectively removed through wet etching or dry etching, while the etching material with a slower etching rate is retained as a skeleton, thereby forming a porous structure; finally, the porous membrane layer 50 is sequentially cleaned and dried to remove residual chemical reagents, dissolved products (such as metal ions after wet etching) and physical debris, so as to avoid contaminating the pore structure of the porous membrane layer 50, and finally an anti-reflection film with a porous structure is obtained.

[0048] For example, in some embodiments, the etching rate of the first material 30 is greater than the etching rate of the second material 40. Under the same etching conditions, the first material 30 will be preferentially removed or eroded more significantly, thereby forming a porous structure in the composite film layer 20, while the second material 40 will be retained more as a skeleton, thereby forming the final porous film layer 50 structure; or, in other embodiments, the etching rate of the first material 30 is less than the etching rate of the second material 40. Under the same etching conditions, the second material 40 will be preferentially removed or eroded more significantly, thereby forming a porous structure in the composite film layer 20, while the first material 30 will be retained more as a skeleton, thereby forming the final porous film layer 50 structure.

[0049] In the actual preparation process, those skilled in the art should be able to control the porosity, pore size (nanometer to micrometer level) and pore distribution of the porous membrane layer 50 by adjusting the etching time, etching temperature, etching solution concentration or etching gas concentration, so as to accurately match the anti-reflection requirements in different application scenarios. As for which material to selectively etch away while retaining another material, those skilled in the art should be able to make reasonable choices and designs based on actual conditions, and no specific restrictions are imposed here. Figure 2 and Figure 3 As shown, the following explanation is given by taking the selective etching of the second material 40 while retaining the first material 30 to obtain the porous membrane layer 50 having the first material 30 as an example.

[0050] Regarding the actual size of the difference in etching rate between the first material 30 and the second material 40 during wet etching or dry etching, those skilled in the art should be able to make reasonable choices and designs based on actual conditions, and no specific restrictions are imposed here. It should be understood that although the etching rates of the first material 30 and the second material 40 during wet etching or dry etching are different, the second material 40 can be selectively etched while retaining the first material 30. However, it is inevitable that part of the first material 30 away from the substrate 10 is etched away, while part of the second material 40 close to the substrate 10 is not etched away. This is because the etching medium will first contact and react with the side away from the substrate 10, and then pass through the pores already formed inside the composite film layer 20 to contact and react with the side close to the substrate 10. However, this does not affect the main purpose of obtaining the porous film layer 50 through the etching process. It should be noted that the etching medium cannot directly etch the composite film layer 20 through the surface of the substrate 10.

[0051] Compared with the prior art, the method for preparing the anti-reflection film provided by the present application utilizes the difference in etching rates, does not require the use of a mask, and directly selectively removes different materials to form an anti-reflection film with a porous structure, which can allow light to be captured and transmitted by the velvet surface multiple times, thereby significantly reducing the reflectivity. At the same time, the method for preparing the anti-reflection film provided by the present application does not require expensive nano-processing equipment (such as an electron beam lithography machine), and can be achieved only by the coating technology commonly used in industry and laboratories combined with wet or dry etching methods, which is suitable for large-scale industrial production. In addition, the method for preparing the anti-reflection film provided by the present application is also more flexible in the selection of materials. The material combination can be adjusted according to the compatibility of the substrate 10 (such as the flexible substrate 10 requires a low-temperature process) and cost requirements (such as replacing precious metals with polymers) to reduce the preparation cost.

[0052] As an practicable manner, S1: depositing a composite material film layer 20 on a substrate 10 includes:

[0053] S11: depositing a composite material film layer 20 on the substrate 10 by physical vapor deposition, chemical vapor deposition or atomic layer deposition.

[0054] It should be noted that physical vapor deposition (PVD) is a technology that vaporizes materials into solid, liquid, or gaseous particles through a physical process and then deposits them onto the surface of the substrate 10 to form a thin film. Its core principle is to use physical means (such as high-energy particle bombardment, heating evaporation, etc.) to separate material atoms or molecules from the source material, and then deposit them on the substrate 10 after being transported through the gas phase. Among them, physical vapor deposition can be vacuum evaporation coating, vacuum sputtering coating, and vacuum ion plating. Physical vapor deposition can achieve alternating deposition of single materials or alloy co-deposition, and has the advantage of a faster deposition rate, but has poor compatibility with complex materials (such as polymers).

[0055] Chemical vapor deposition (CVD) is a technique that deposits gaseous precursor materials onto the surface of a substrate 10 through a chemical reaction to form a solid thin film. Its core principle is that gaseous reactants decompose or chemically react under conditions such as high temperature, plasma, or a catalyst to produce a solid product that is deposited as a thin film, while simultaneously releasing byproduct gases. CVD can precisely control the atomic-level mixing of the first material 30 and the second material 40 by adjusting the gas flow ratio. It requires high temperature or plasma assistance and is more suitable for high-temperature-resistant substrates 10 (such as crystalline silicon).

[0056] Atomic layer deposition (ALD) is an ultra-thin film deposition technology based on a self-limiting surface reaction. Its core principle is to chemically deposit layer by layer by alternately pulsed vapor precursors into a reaction chamber and adsorb them onto the surface of a substrate 10, ultimately forming a uniform, dense film with precisely controllable thickness. The composite film layer 20 produced by ALD is extremely uniform and can cover the inner surface of a substrate 10 with complex three-dimensional structures (such as nanopores and grooves). Although the deposition rate is slow, the composition is controlled with extremely high precision, making it suitable for anti-reflection applications where film thickness is sensitive (such as optical interference films).

[0057] Regarding the actual selection of the coating technology used to deposit the composite material film layer 20, those skilled in the art should be able to make reasonable selections and designs based on actual conditions such as the characteristics of the substrate 10, the structural requirements of the composite material film layer 20, and the compatibility of subsequent etching processes. No specific restrictions are imposed here.

[0058] As an practicable manner, S2: wet etching or dry etching the composite material membrane layer 20 to obtain the porous membrane layer 50 includes:

[0059] S21: wet-etching the composite material membrane layer 20 with an etching solution to obtain a porous membrane layer 50, wherein the etching temperature is between 20 and 150°C.

[0060] It should be noted that wet etching utilizes an etching solution to chemically react with the materials in the composite film layer 20, thereby selectively removing portions of the materials to form a porous structure. During this process, because the composite film layer 20 comprises a first material 30 and a second material 40 having different etching rates, the etching solution preferentially reacts with and dissolves the material with the faster etching rate, while the material with the slower etching rate is relatively retained, gradually forming the porous film layer 50.

[0061] When the etching temperature is close to 20°C, the etching reaction rate is relatively slow, and the etching process is more gentle and controllable, which helps to accurately control the degree of etching and the formation of porous structures, reducing the risk of over-etching. It is especially suitable for situations where high requirements are placed on the film structure and fine control is required. When the etching temperature is close to 150°C, the etching reaction rate will accelerate, and the etching process can be completed in a shorter time, thereby improving production efficiency. However, high temperature may cause thermal expansion and deformation of the film layer. Therefore, it is necessary to strictly control the temperature while ensuring the etching efficiency to avoid adverse effects.

[0062] As an practicable manner, the etching solution is oxalic acid, hydrofluoric acid, sodium carbonate, phosphoric acid, nitric acid or sodium hydride. Regarding the actual selection of the etching solution, those skilled in the art should be able to make a reasonable selection and design according to the actual situation, and no specific limitation is made here.

[0063] As an practicable manner, S2: wet etching or dry etching the composite material membrane layer 20 to obtain the porous membrane layer 50 includes:

[0064] S22: dry-etching the composite material membrane layer 20 with an etching gas to obtain a porous membrane layer 50, wherein the etching temperature is between 20°C and 150°C.

[0065] It should be noted that dry etching utilizes active species (such as ions and free radicals) generated by an etching gas in a plasma environment to physically or chemically react with the materials in the composite film layer 20, thereby etching the film layer. In the composite film layer 20, due to the different etching rates of the first material 30 and the second material 40, the active species preferentially react with and remove the material with the faster etching rate, while the material with the slower etching rate is relatively retained, ultimately forming the porous film layer 50.

[0066] When the etching temperature is close to 20°C, the etching reaction rate is relatively slow, the energy of the active particles is low, and the etching process is more gentle and controllable, which helps to accurately control the degree of etching and the formation of porous structures, reducing the risk of over-etching. It is especially suitable for situations where high requirements are placed on the film structure and fine control is required; when the etching temperature is close to 150°C, the etching reaction rate will accelerate, the energy of the active particles will increase, and the etching process can be completed in a shorter time, thereby improving production efficiency. However, high temperature may cause thermal expansion, deformation and other problems of the film layer. Therefore, it is necessary to strictly control the temperature while ensuring the etching efficiency to avoid adverse effects.

[0067] As an operative method, the etching gas is argon, oxygen, trifluoromethane, carbon tetrafluoride, sulfur hexafluoride, octafluorocyclobutane, or a mixture thereof. Regarding the actual selection of the etching gas, those skilled in the art should be able to make a reasonable selection and design based on the actual situation, and no specific limitation is imposed here.

[0068] As an practicable method, S3: sequentially cleaning and drying the porous membrane layer 50 includes:

[0069] S31: Cleaning the porous membrane layer 50 by an ultrasonic cleaning machine;

[0070] It should be noted that the substrate 10 formed with the porous film layer 50 is placed in an ultrasonic cleaning tank filled with a cleaning solution (usually deionized water, an organic solvent such as ethanol, etc.), and an ultrasonic generator is turned on. Ultrasonic waves propagate in the cleaning solution, performing an all-around cleaning of the porous film layer 50. Since the porous film layer 50 has a rich pore structure, the cavitation effect of the ultrasonic wave can penetrate deep into the pores, removing contaminants that are difficult to reach with other cleaning methods, thereby ensuring the cleanliness of the porous film layer 50.

[0071] S32: Drying the porous membrane layer 50 by a centrifuge or a drying machine, wherein the drying temperature of the drying machine is between 50 and 120°C.

[0072] It should be noted that drying in a dryer utilizes hot air to heat the porous membrane layer 50, evaporating the cleaning solution and achieving drying. The dryer temperature can be controlled between 50°C and 120°C, preventing damage to the membrane layer caused by improper drying methods or excessive temperatures. This helps maintain the original structure and performance of the porous membrane layer 50, thereby improving product yield.

[0073] Thorough cleaning and drying removes impurities and moisture from the surface and interior of the film, minimizing performance changes caused by these impurities and moisture. For example, impurities can affect the film's electrical and optical properties; moisture can reduce the film's chemical stability, making it susceptible to oxidation and hydrolysis. Cleaning and drying effectively improve the film's performance stability and reliability.

[0074] As an practicable manner, the thickness of the composite film layer 20 is between 10 and 1000 nm. For example, the thickness of the composite film layer 20 is 10 nm, 50 nm, 100 nm, 200 nm, 500 nm, 800 nm or 1000 nm. As an practicable manner, the substrate 10 is glass, crystalline silicon, sapphire or plastic. As an practicable manner, the first material 30 and the second material 40 are silicon dioxide, aluminum oxide, titanium dioxide, hafnium dioxide, tantalum pentoxide, niobium pentoxide or zirconium oxide. Regarding the actual selection of the substrate 10, the first material 30 and the second material 40, those skilled in the art should be able to make reasonable selections and designs according to actual conditions, and no specific restrictions are imposed here.

[0075] like Figure 2 and Figure 3 As shown, in a second aspect of an embodiment of the present application, an anti-reflection film is provided. The anti-reflection film is prepared by the above-mentioned method for preparing the anti-reflection film.

[0076] It should be noted that the specific structure of the anti-reflection film provided in this embodiment is the same as the method for preparing the anti-reflection film described above. Those skilled in the art can infer the specific structure of the anti-reflection film based on the description of the method for preparing the anti-reflection film described above, and this application will not repeat the description. Since the anti-reflection film provided in this embodiment is produced using the above-mentioned method for preparing the anti-reflection film, the anti-reflection film has the same beneficial effects as the above-mentioned method for preparing the anti-reflection film, and will not be further described here.

[0077] Please refer to Figure 4 and Figure 5 , which are the transmittance and reflectance of the composite film layer 20 of Al2O3 and SiO2 deposited by magnetron sputtering before and after phosphoric acid wet etching. ML02-0 is the curve of the sample before etching, ML02-1 is the curve of the sample after etching at a temperature of 50°C and a time of 60 minutes, ML02-2 is the curve of the sample after etching at a temperature of 40°C and a time of 60 minutes, and ML02-3 is the curve of the sample after etching at a temperature of 50°C and a time of 60 minutes, and then at a temperature of 40°C and a time of 60 minutes.

[0078] A third aspect of the present invention provides an optical device comprising the anti-reflection film. Since the structure and beneficial effects of the anti-reflection film have been described in detail in the above embodiments, they will not be repeated here.

[0079] The foregoing description is merely an optional embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

[0080] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

Claims

1. A method for preparing an anti-reflection film, characterized in that: The method comprises: Depositing a composite material film layer on a substrate, wherein the composite material film layer comprises a first material and a second material, and the first material and the second material have different etching rates during wet etching or dry etching; Wet etching or dry etching the composite material film layer to obtain a porous film layer; The porous membrane layer is sequentially cleaned and dried.

2. The method for preparing an anti-reflection film according to claim 1, wherein: Depositing a composite material film layer on a substrate comprises: The composite film layer is deposited on the substrate by physical vapor deposition, chemical vapor deposition or atomic layer deposition.

3. The method for preparing an anti-reflection film according to claim 1, wherein: The step of wet etching or dry etching the composite material film layer to obtain a porous film layer comprises: The composite material membrane layer is wet-etched by an etching solution to obtain a porous membrane layer, wherein the etching temperature is between 20 and 150°C.

4. The method for preparing an anti-reflection film according to claim 3, wherein: The etching solution is oxalic acid, hydrofluoric acid, sodium carbonate, phosphoric acid, nitric acid or sodium hydride.

5. The method for preparing an anti-reflection film according to claim 1, wherein: The step of wet etching or dry etching the composite material film layer to obtain a porous film layer comprises: The composite material membrane layer is dry-etched by etching gas to obtain a porous membrane layer, wherein the etching temperature is between 20 and 150°C.

6. The method for preparing an anti-reflection film according to claim 5, wherein: The etching gas is at least one of argon, oxygen, trifluoromethane, carbon tetrafluoride, sulfur hexafluoride and octafluorocyclobutane.

7. The method for preparing an anti-reflection film according to claim 1, wherein: The sequentially cleaning and drying of the porous membrane layer comprises: Cleaning the porous membrane layer by an ultrasonic cleaning machine; The porous membrane layer is dried by a centrifuge or a drying machine, wherein the drying temperature of the drying machine is between 50 and 120°C.

8. The method for preparing an anti-reflection film according to claim 1, wherein: The thickness of the composite material film layer is between 10 and 1000 nm.

9. The method for preparing an anti-reflection film according to claim 1, wherein: The substrate is glass, crystalline silicon, sapphire or plastic.

10. The method for preparing an anti-reflection film according to claim 1, wherein: The first material and the second material are silicon dioxide, aluminum oxide, titanium dioxide, hafnium dioxide, tantalum pentoxide, niobium pentoxide or zirconium oxide.

11. An anti-reflection film, characterized in that: The anti-reflection film is prepared by the method for preparing the anti-reflection film according to any one of claims 1 to 10.

12. An optical device, characterized in that: The anti-reflection film according to claim 11 is included.

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