Optical thin film, preparation method of refractive index adjustable film layer and optical element

Abstract

The invention discloses an optical thin film, a preparation method of a refractive index adjustable film layer and an optical element. The method comprises: providing a monomer or a compound of a monomer on a substrate; the method comprises the following steps: preparing a monomer or a compound of the monomer, enabling the monomer or the compound of the monomer to chemically react with at least two gases so as to generate a target film layer on a base material, and generating the target film layer with an adjustable refractive index on the base material by adjusting the flow ratio of the at least two gases in the chemical reaction process. According to the optical thin film and the preparation method thereof, the film layer with the adjustable refractive index can be obtained through a one-time preparation process, so that a material with the specified refractive index can be flexibly prepared; the complete optical film can be prepared only by using the monomer or the compound of the monomer as the raw material, the process is simple, the flow is few, the cost is reduced, and the manufacturing efficiency is improved.

Description

Technical Field

[0001] Embodiments of the present application relate to the technical field of optical coating, and particularly to an optical thin film, a preparation method of a refractive index adjustable film layer, and an optical element. Background Art

[0002] Optical coating is a commonly used technology in optical processing. Currently, the film materials used in optical coating are all materials with fixed refractive indices. According to the design principle of optical coating theory, the design and processing of the film system will inevitably involve the use of multiple film materials. Therefore, the existing optical coating methods have the following problems when preparing optical thin films:

[0003] 1. The optical thin film adopts a design of alternately stacking high refractive index film layers and low refractive index film layers. The use of multiple film materials is involved in the same film system, with complex processes, many procedures, and high costs;

[0004] 2. The characteristics of the materials limit the selectivity of the refractive index, and it is impossible to flexibly prepare materials with specified refractive indices. Summary of the Invention

[0005] The optical thin film, the preparation method of the refractive index adjustable film layer, and the optical element provided by the embodiments of the present application can solve or partially solve the above deficiencies or other deficiencies in the prior art.

[0006] According to a first aspect of the present application, an optical thin film is provided. The optical thin film includes at least one monomer or monomer compound and at least two gas elements, and is prepared through one process.

[0007] In an embodiment of the present application, the refractive index of the optical thin film can be adjusted by adjusting the flow ratio of the at least two gas elements in the one process.

[0008] In an embodiment of the present application, the monomer includes one of aluminum, boron, and silicon monomers or one of the complexes of aluminum, boron, and silicon.

[0009] In an embodiment of the present application, the refractive index of the optical thin film can be adjusted within the range of 1.65 to 1.98.

[0010] In an embodiment of the present application, the optical thin film includes an AlOxNy thin film, where x and y respectively refer to the ratio of the number of O and N atoms to one Al atom, and are respectively ≥ 0, and cannot be 0 at the same time.

[0011] In one embodiment of the present application, in AlOxNy, x / y satisfies: x / y = 2.03K * [exp(F1 / 1.44F2) - 1]; where K is the power of the ion source; F1 is the volume flow rate of oxygen that undergoes a chemical reaction with aluminum monomers or aluminum compounds; and F2 is the volume flow rate of nitrogen that undergoes a chemical reaction with aluminum monomers or aluminum compounds.

[0012] In one embodiment of the present application, K is 0 to 6 kW, F1 is 0 to 300 sccm, and F2 is 0 to 300 sccm.

[0013] In one embodiment of the present application, the refractive index n of the AlOxNy thin film satisfies:

[0014]

[0015] In one embodiment of the present application, the optical thin film includes an antireflection film having an alternating stacked structure of high refractive index film layers and low refractive index film layers.

[0016] In one embodiment of the present application, the reflectivity R of the antireflection film satisfies: R ≤ 5%.

[0017] In one embodiment of the present application, the equivalent optical path of the antireflection film is an odd multiple of λ / 4, where λ is the wavelength of the light in the wavelength band used by the antireflection film.

[0018] In one embodiment of the present application, the thickness of the high refractive index film layer is 5 to 80 nm, and the thickness of the low refractive index film layer is 20 to 100 nm.

[0019] In one embodiment of the present application, the antireflection film is formed by alternately stacking high refractive index AlN film layers and low refractive index Al2O3 film layers.

[0020] In one embodiment of the present application, the optical thin film includes an antireflection film with a micro-nano structure.

[0021] In one embodiment of the present application, the reflectivity R of the antireflection film satisfies: R ≤ 5%.

[0022] In one embodiment of the present application, the thickness of the antireflection film is 300 to 370 nm.

[0023] In one embodiment of the present application, the optical thin film is prepared in one process step by one of the processes of magnetron sputtering, electron beam evaporation, vacuum coating, and chemical vapor deposition.

[0024] According to a second aspect of the present application, a method for preparing a film layer with adjustable refractive index is provided, including: providing a monomer or a compound of a monomer on a substrate; causing the monomer or the compound of the monomer to chemically react with at least two gases to generate a target film layer on the substrate, wherein during the chemical reaction process, by adjusting the flow rate ratio of the at least two gases, the target film layer with adjustable refractive index is generated on the substrate.

[0025] In an embodiment of the present application, the refractive index of the target film layer is adjustable within the range of 1.65 to 1.98.

[0026] In an embodiment of the present application, the monomer or the compound of the monomer includes: an aluminum monomer or a compound of aluminum, the at least two gases include: oxygen and nitrogen, and the target film layer includes: an AlOxNy film layer, wherein x and y respectively refer to the ratio of the number of O and N atoms to one Al atom, and are respectively ≥ 0, and cannot be 0 at the same time.

[0027] In an embodiment of the present application, in AlOxNy, x / y satisfies: x / y = 2.03K * [exp(F1 / 1.44F2) - 1]; where K is the power of the ion source; F1 is the volume flow rate of oxygen that chemically reacts with the aluminum monomer or the compound of aluminum; and F2 is the volume flow rate of nitrogen that chemically reacts with the aluminum monomer or the compound of aluminum.

[0028] In an embodiment of the present application, K is 0 to 6 kW, F1 is 0 to 300 sccm, and F2 is 0 to 300 sccm.

[0029] In an embodiment of the present application, the refractive index n of the AlOxNy film layer satisfies:

[0030]

[0031] In an embodiment of the present application, the step of causing the monomer or the compound of the monomer to chemically react with at least two gases to generate a target film layer on the substrate includes: by adjusting the flow rate ratio of the at least two gases, generating an antireflection film with an alternating stacked structure of a high refractive index film layer and a low refractive index film layer on the substrate.

[0032] In an embodiment of the present application, the reflectivity R of the antireflection film ≤ 5%.

[0033] In an embodiment of the present application, the equivalent optical path of the antireflection film is an odd multiple of λ / 4, where λ is the wavelength of the light in the band used by the antireflection film.

[0034] In one embodiment of the present application, the thickness of the high refractive index film layer is 5 - 80 nm, and the thickness of the low refractive index film layer is 20 - 100 nm.

[0035] In one embodiment of the present application, the antireflection film is formed by alternately stacking a high refractive index AlN film layer and a low refractive index Al2O3 film layer.

[0036] In one embodiment of the present application, after the step of causing the monomer or the compound of the monomer to chemically react with at least two gases to generate a target film layer on the substrate, the method further includes: causing the target film layer to undergo a hydrolysis reaction to generate a micro-nano structured antireflection film on the substrate.

[0037] In one embodiment of the present application, the reflectance R of the antireflection film is ≤ 5%.

[0038] In one embodiment of the present application, the thickness of the target film layer is 100 - 150 nm, and the thickness of the antireflection film is 300 - 370 nm.

[0039] In one embodiment of the present application, the target film layer includes an AlO1N2 film layer. Among them, the step of generating a micro-nano structured antireflection film on the substrate includes: causing the AlO1N2 film layer to undergo a hydrolysis reaction under the condition of a 95°C water bath to generate a micro-nano structured antireflection film on the substrate.

[0040] In one embodiment of the present application, the target film layer includes an AlN film layer; among them, the step of generating a micro-nano structured antireflection film on the substrate includes: causing the AlN film layer to undergo a hydrolysis reaction under the condition of a 65°C water bath to generate a micro-nano structured antireflection film on the substrate.

[0041] In one embodiment of the present application, the step of causing the monomer or the compound of the monomer to chemically react with at least two gases to generate a target film layer on the substrate includes: causing the monomer or the compound of the monomer to chemically react with the at least two gases to generate the target film layer through one of the processes of magnetron sputtering, electron beam evaporation, vacuum coating, and chemical vapor deposition.

[0042] According to a third aspect of the present application, an optical element is provided, including: a light-transmitting substrate; and an optical thin film, the optical thin film being coated on the light-transmitting substrate and including a film layer prepared by using the preparation method of the refractive index adjustable film layer described in the second aspect.

[0043] An optical thin film, a method for preparing a refractive index adjustable film layer, and an optical element provided according to an embodiment of the present application can obtain a film layer with adjustable refractive index through a single preparation process by using a monomer or a compound of a monomer as a raw material and adjusting the flow ratio of at least two gases. Thus, a material with a specified refractive index can be flexibly prepared. When preparing an optical thin film with an alternating stack design of a high refractive index film layer and a low refractive index film layer, a complete optical thin film can be prepared only by using a monomer or a compound of a monomer as a raw material. The process is simple and has fewer steps, which is beneficial to reducing costs and improving manufacturing efficiency.

[0044] The content described in this part is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it used to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, objectives, and advantages of the present application will become more apparent. The drawings are used to better understand the solution and do not constitute a limitation to the present application. Among them:

[0046] Figure 1 is a schematic diagram of a method for preparing a refractive index adjustable film layer according to an embodiment of the present application;

[0047] Figure 2 is a schematic diagram of a film layer prepared according to the method of the present application when the flow rates of oxygen and nitrogen are in one ratio;

[0048] Figure 3 is a schematic diagram of a film layer prepared according to the method of the present application when the flow rates of oxygen and nitrogen are in another ratio;

[0049] Figure 4 is a schematic diagram of the reflectance of an antireflection film with an alternating stack structure prepared according to the method of the present application in the visible light band;

[0050] Figure 5 is a schematic diagram of an antireflection film with a micro-nano structure prepared according to the method of the present application;

[0051] Figure 6 is a scanning electron microscope image of an antireflection film with a micro-nano structure prepared according to the method of the present application;

[0052] Figure 7 is a schematic diagram of the reflectance of an antireflection film with a micro-nano structure prepared according to the method of the present application in the visible light band;

[0053] Figure 8 is a schematic diagram of implementing the method of the present application using an electron beam evaporation process;

[0054] Figure 9 It is another scanning electron microscope image of the antireflection film with micro-nano structure prepared by the method according to the present application. Detailed implementation manners

[0055] The following describes exemplary embodiments of the present application with reference to the accompanying drawings. Various details of the embodiments of the present application are included to facilitate understanding, and they should be considered merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0056] In the accompanying drawings, for ease of illustration, the thickness, dimensions, and shapes of the components have been slightly adjusted. The drawings are for illustrative purposes only and are not drawn to an exact scale. As used herein, terms such as "substantially", "about", and similar terms are used as terms indicating approximation, rather than terms indicating degree, and are intended to account for the inherent deviations in measured or calculated values that would be recognized by those of ordinary skill in the art.

[0057] It should also be understood that expressions such as "including", "comprising", "having", "containing", and / or "comprising of" are open-ended rather than closed-ended expressions in this specification, which means the presence of the stated features, elements, and / or components, but do not exclude the presence of one or more other features, elements, components, and / or their combinations. In addition, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of features, rather than just individual elements in the list. In addition, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". And the term "exemplary" is intended to refer to an example or illustration.

[0058] Unless otherwise defined, all terms used herein (including engineering terms and technical terms) have the same meaning as commonly understood by those of ordinary skill in the art to which the present application pertains. It should also be understood that, unless explicitly stated in the present application, words defined in a common dictionary should be interpreted as having a meaning consistent with their meaning in the context of the related art, and should not be interpreted in an idealized or overly formal sense.

[0059] It should be noted that, without conflict, the embodiments and features in the embodiments of the present application can be combined with each other. In addition, unless explicitly defined or inconsistent with the context, the specific steps included in the methods described in the present application do not have to be limited to the recorded order, but can be executed in any order or executed in parallel.

[0060] In addition, those skilled in the art can understand that the quantities shown in the accompanying drawings of this application and in the following text, such as the quantity of the optical film, etc., are only shown for convenience of illustration. Without departing from the teachings of the disclosed content of this application, the specific quantity can be set according to actual needs.

[0061] Optical coating is a commonly used technology in optical processing. It is to deposit a thin film with specific optical properties on the surface of an optical element to change the optical properties such as reflection, transmission, and absorption of the optical element.

[0062] Currently, the film materials used in optical coating are all materials with fixed refractive indices. According to the design principle of optical coating theory, the design and processing process of the film system will inevitably involve the use of multiple film materials. Therefore, the existing optical coating methods have the following problems when preparing optical thin films:

[0063] 1. The optical thin film adopts a design of alternating stacking of high-refractive-index film layers and low-refractive-index film layers. Multiple film materials are used in combination in the same film system, with complex processes, many procedures, and high costs;

[0064] 2. The characteristics of the materials limit the selectivity of the refractive index, and it is impossible to flexibly prepare materials with a specified refractive index.

[0065] To solve the above problems, an embodiment of this application provides a preparation method 1000 for a refractive-index adjustable film layer.

[0066] Figure 1 The schematic diagram of the preparation method 1000 for a refractive-index adjustable film layer according to an embodiment of this application is shown. As Figure 1 shown, the preparation method 1000 for a refractive-index adjustable film layer may include: providing a monomer or a compound of a monomer on a substrate 110; causing the monomer or the compound of the monomer to chemically react with at least two gases to generate a target film layer 120 on the substrate 110. Among them, during the chemical reaction process, by adjusting the flow ratio of at least two gases, a target film layer 120 with a controllable refractive index is generated on the substrate 110.

[0067] The preparation method 1000 for a refractive-index adjustable film layer according to an embodiment of this application uses a monomer or a compound of a monomer as a raw material, activates at least two gases to chemically react with the monomer or the compound of the monomer, and generates a target film layer 120 on the substrate 110. During the preparation process of the target film layer 120, by adjusting the flow ratio of at least two gases, the ratio of the atoms corresponding to at least two gases in the generated target film layer 120 can be changed, thereby changing the refractive index of the corresponding target film layer 120, so that the refractive index of the generated target film layer 120 can be adjusted.

[0068] Embodiments of the present application also provide an optical thin film 120, which includes at least one monomer or monomer compound and at least two gaseous elements and is prepared by a single process.

[0069] As can be seen from the above, in the method for preparing a refractive index tunable film layer according to the embodiments of the present application, by using a monomer or a compound of a monomer as a raw material and adjusting the flow rate ratio of at least two gases, a film layer with a tunable refractive index can be obtained through a single preparation process, so that a material with a specified refractive index can be flexibly prepared. When preparing an optical thin film with an alternating stack design of high refractive index film layers and low refractive index film layers, a complete optical thin film can be prepared only by using a monomer or a compound of a monomer as a raw material. The process is simple and has few steps, which is beneficial to reducing costs and improving manufacturing efficiency. Specifically, in a single preparation process, by using a monomer or a compound of a monomer as a raw material and adjusting the flow rate ratio of at least two gases, for example, by changing the gas flow rate to change the content of gaseous elements in the optical thin film, thereby regulating the refractive index of the optical thin film.

[0070] It should be noted that the monomer or monomer compound used as a raw material in the embodiments of the present application can be an aluminum monomer or a compound of aluminum, a silicon monomer or a compound of silicon, a boron monomer or a compound of boron, a titanium monomer or a compound of titanium, a niobium monomer or a compound of niobium, a tantalum monomer or a compound of tantalum, etc. Or, it can also be a composite of at least two of the above-mentioned aluminum, silicon, boron, titanium, and niobium and a compound of the composite. The embodiments of the present application do not limit the type of the monomer or monomer compound in method 1000.

[0071] It should be noted that the gases that chemically react with the monomer or monomer compound in the embodiments of the present application can include at least two of oxygen, nitrogen, hydrogen, methane, acetylene, carbon-containing compounds, etc. The embodiments of the present application do not limit the type and quantity of the at least two gases in method 1000.

[0072] It should be understood that the steps shown in method 1000 in the embodiments of the present application are not exclusive, and other steps can also be performed before, after, or between the steps shown in method 1000.

[0073] It should be noted that the embodiments of the present application do not limit the material of the substrate in method 1000, that is, the material and type of the substrate 110. For example, the material of the substrate 110 can be glass or plastic, etc., and the type of the substrate 110 can be any optical element that requires optical coating.

[0074] It should be noted that the embodiments of the present application do not limit the thickness of the target film layer 120 prepared by the method 1000, the type of the optical film formed or generated by the target film layer 120, etc.

[0075] In some alternative embodiments, the refractive index of the optical film 120 can be adjusted by adjusting the flow rate ratio of at least two gas elements in one process. Optionally, the refractive index of the optical film 120 can be adjusted within the range of 1.65 to 1.98.

[0076] In some alternative embodiments, as Figure 1 shown, the monomer or the compound of the monomer as the raw material may include: aluminum monomer or aluminum compound, and at least two gases may include: oxygen and nitrogen. The target film layer 120 may include: AlOxNy film layer, where x and y respectively refer to the ratio of the number of O and N atoms to one Al atom, and are respectively ≥ 0 and cannot be 0 at the same time.

[0077] In an alternative example, when the flow rate of oxygen that chemically reacts with the aluminum monomer or aluminum compound is 0, the product at this time is all AlN, x in AlOxNy is 0, and the refractive index of the AlN film layer is 1.98. In another alternative example, when the flow rate of nitrogen that chemically reacts with the aluminum monomer or aluminum compound is 0, the product at this time is all Al2O3, y in AlOxNy is 0, and the refractive index n of the Al2O3 film layer is 1.65. Thus, by adjusting the flow rate ratio of oxygen and nitrogen, an AlOxNy film layer with a refractive index adjustable within the range of 1.65 to 1.98 can be generated.

[0078] Optionally, in AlOxNy, x / y can satisfy the conditional formula: x / y = 2.03K * [exp(F1 / 1.44F2) - 1]. Here, K is the power of the ion source; F1 is the volume flow rate of oxygen that undergoes a chemical reaction with aluminum monomers or compounds of aluminum; F2 is the volume flow rate of nitrogen that undergoes a chemical reaction with aluminum monomers or compounds of aluminum. According to the above conditional formula, under the condition of a certain power of the ion source, by changing the ratio of the volume flow rates of oxygen and nitrogen, x / y in AlOxNy can be changed, realizing the control of x / y in AlOxNy. And changing x / y in AlOxNy is to change the composition ratio of each chemical component in AlOxNy. Different composition ratios of each chemical component in AlOxNy correspond to different refractive indices of the material. Therefore, by controlling x / y in AlOxNy, the regulation of the refractive index of the generated material can be achieved. For example, when a material with a higher refractive index needs to be prepared, the refractive index of the AlOxNy film layer can be increased by directly controlling a smaller oxygen flow rate and a larger nitrogen flow rate, so that the ratio of x / y in AlOxNy is smaller. This process only requires adjusting the nitrogen and oxygen flow rates and can be completed in one preparation process without changing the monomer type and / or gas type. The operation of one preparation process is simple and the process is less. However, the existing preparation process requires changing the monomer type and / or gas type and then regulating the gas flow rate. Changing the monomer type and / or gas type requires re-adjusting the equipment, and the operation process is complex with multiple processes, resulting in huge costs.

[0079] Optionally, in one preparation process of this application, the value range of K can be 0 - 6 kW, the value range of F1 can be 0 - 300 sccm, and the value range of F2 can be 0 - 300 sccm.

[0080] Optionally, the refractive index n of the AlOxNy film layer can satisfy the conditional formula: Wherein, K is the power of the ion source; F1 is the volume flow rate of oxygen that chemically reacts with aluminum monomers or aluminum compounds; F2 is the volume flow rate of nitrogen that chemically reacts with aluminum monomers or aluminum compounds. According to the above conditional formula, under the condition of a certain power of the ion source, by changing the ratio of the volume flow rates of oxygen and nitrogen, the refractive index of the AlOxNy film layer can be changed, realizing the control of the refractive index of the AlOxNy film layer, and thus the refractive index of the generated material can be accurately controlled within the range of 1.65 to 1.98 quantitatively. For example, when F1 is controlled to be 0 sccm and F2 is controlled to be 100 sccm, x / y in AlOxNy is 0, the AlOxNy film layer is an AlN film layer, and the refractive index n is 1.98; when F1 is controlled to be 100 sccm and F2 is controlled to be 50 sccm, x / y in AlOxNy is 6 / 1, the AlOxNy film layer is an AlO6N1 film layer, and the refractive index is 1.67; when F1 is controlled to be 200 sccm and F2 is controlled to be 0 sccm, x / y in AlOxNy approaches positive infinity, the AlOxNy film layer is an Al2O3 film layer, and the refractive index n is 1.65.

[0081] In some alternative embodiments, the step of causing a monomer or a compound of a monomer to chemically react with at least two gases to form a target film layer on a substrate may include: generating an antireflection film having an alternating stacked structure of a high refractive index film layer and a low refractive index film layer on the substrate by adjusting the flow rate ratio of at least two gases. By adjusting the flow rate ratio of at least two gases, it is possible to use only one monomer or a compound of a monomer as a raw material to prepare film layers with different refractive indices. By combining the high refractive index film layer and the low refractive index film layer, an antireflection film can be prepared, realizing the preparation of an antireflection film only by controlling the preparation process. The preparation process is simple, with fewer steps, which is beneficial to reducing costs and improving manufacturing efficiency. As an example, the optical thin film 120 of the embodiment of the present application may include an antireflection film having an alternating stacked structure of a high refractive index film layer and a low refractive index film layer.

[0082] Optionally, the reflectivity R of the antireflection film with an alternating stacked structure provided by the embodiment of the present application is ≤ 5%. Optionally, the equivalent optical path of the antireflection film with an alternating stacked structure provided by the embodiment of the present application may be an odd multiple of λ / 4, where λ is the wavelength of the light in the band used by the antireflection film with an alternating stacked structure. Optionally, in the antireflection film with an alternating stacked structure provided by the embodiment of the present application, the thickness of the high refractive index film layer may be 5 to 80 nm, and the thickness of the low refractive index film layer may be 20 to 100 nm. In an alternative example, the antireflection film with an alternating stacked structure provided by the embodiment of the present application may be formed by alternately stacking a high refractive index AlN film layer and a low refractive index Al2O3 film layer.

[0083] When the antireflection film with an alternating stacking structure provided by the embodiment of the present application is applied to an optical lens, it can reduce the reflection of the optical lens, improve the transmittance, and make the observation effect clearer. When applied to a photoelectric conversion element, it can improve the photoelectric conversion efficiency. At the same time, when the antireflection film with an alternating stacking structure provided by the embodiment of the present application is applied to an optical lens, it can also effectively reduce the risk of ghost images of the optical lens and can have a good effect of reducing stray light. Further, the antireflection film with an alternating stacking structure provided by the embodiment of the present application can also selectively reduce or enhance the transmittance of light with a specific wavelength through the design of the film layer to achieve the effect of light filtering.

[0084] In some other alternative embodiments, after the step of reacting a monomer or a compound of the monomer with at least two gases to form a target film layer on a substrate, it may further include: subjecting the target film layer to a hydrolysis reaction to form an antireflection film with a micro-nano structure on the substrate. As an example, the optical thin film 120 of the embodiment of the present application may include an antireflection film with a micro-nano structure.

[0085] Optionally, the reflectivity R of the antireflection film with a micro-nano structure provided by the embodiment of the present application is ≤5%. For example, the antireflection film with a micro-nano structure may have an ultra-low reflectivity, and its reflectivity may even be lower than 0.1%. Optionally, the thickness of the target film layer before the hydrolysis reaction may be 100 - 150 nm, and the thickness of the antireflection film with a micro-nano structure after the hydrolysis reaction may be 300 - 370 nm.

[0086] When the antireflection film with a micro-nano structure provided by the embodiment of the present application is applied to an optical lens, it can reduce the reflection of the optical lens, improve the transmittance, and make the observation effect clearer. When applied to a photoelectric conversion element, it can improve the photoelectric conversion efficiency. At the same time, when the antireflection film with a micro-nano structure provided by the embodiment of the present application is applied to an optical lens, it can also effectively reduce the risk of ghost images of the optical lens and can have a good effect of reducing stray light. Further, the antireflection film with a micro-nano structure provided by the embodiment of the present application can also selectively reduce or enhance the transmittance of light with a specific wavelength through the design of the film layer to achieve the effect of light filtering.

[0087] In some alternative embodiments, the step of causing a monomer or a compound of a monomer to chemically react with at least two gases to form a target film layer on a substrate may include: causing a monomer or a compound of a monomer to chemically react with at least two gases to form a target film layer by one of processes such as magnetron sputtering, electron beam evaporation, vacuum coating, chemical vapor deposition, etc. The preparation of a refractive index tunable film layer can be achieved through a variety of optical coating processes, and the preparation methods are diversified, which can make the degree of freedom in preparing a refractive index tunable film layer wider. As an example, the optical thin film 120 of the embodiments of the present application can be prepared in a single process step by one of magnetron sputtering, electron beam evaporation, vacuum coating, chemical vapor deposition.

[0088] The preparation method 1000 of a refractive index tunable film layer provided by the embodiments of the present application will be described below with reference to the accompanying drawings in conjunction with specific embodiments.

[0089] In an alternative embodiment of the present application, an AlOxNy film layer is prepared on a substrate by a magnetron sputtering process. Among them, an aluminum monomer is used as a target, oxygen and nitrogen are introduced into an inductively coupled plasma (ICP) ion source, the oxygen and nitrogen are activated, and the ionized oxygen ions and nitrogen ions chemically react with the aluminum monomer to form an AlOxNy film layer on the substrate. When the power of the ICP ion source is 1 kW, the flow ratio of the introduced oxygen and nitrogen is controlled by a controller, such as a mass flow controller (MFC), to achieve the regulation of the refractive index of the AlOxNy film layer formed on the substrate. As Figure 2 shown, when the flow rate of the directly introduced oxygen controlled by the controller is 100 sccm and the flow rate of the introduced nitrogen is 50 sccm, the AlOxNy film layer formed on the substrate 210 is an AlO6N1 film layer 221. At this time, x / y is 6 / 1, and the refractive index of the AlO6N1 film layer 221 is 1.67. As Figure 3 shown, when the flow rate of the directly introduced oxygen controlled by the controller is 10 sccm and the flow rate of the introduced nitrogen is 300 sccm, the AlOxNy film layer formed on the substrate 210 is an AlO1N20 film layer 222. At this time, x / y is 1 / 20, and the refractive index of the AlO1N20 film layer 222 is 1.81. In Figure 2 and Figure 3 the shown embodiments, as the proportion of nitrogen introduced increases, the value of x / y in the generated material gradually decreases, and the refractive index of the material gradually increases.

[0090] In another alternative embodiment of the present application, an antireflection film is prepared on a substrate by a magnetron sputtering process. The antireflection film is formed by alternately stacking high-refractive-index AlOxNy film layers and low-refractive-index AlOxNy film layers. Among them, aluminum monomer is used as the target, oxygen and nitrogen are introduced into the ICP ion source, and oxygen and nitrogen are activated, so that the ionized oxygen ions and nitrogen ions react chemically with the aluminum monomer. When the power of the ICP ion source is 1 kW, the flow ratio of the introduced oxygen and nitrogen is controlled by the MFC, and a structure in which high-refractive-index AlOxNy film layers and low-refractive-index AlOxNy film layers are alternately stacked is formed on the substrate. Among them, when the flow rate of the introduced oxygen controlled by the MFC is 0 sccm and the flow rate of the introduced nitrogen is 100 sccm, an AlN film layer is formed on the substrate, and the refractive index of the AlN film layer is 1.98. When the flow rate of the introduced oxygen controlled by the MFC is 200 sccm and the flow rate of the introduced nitrogen is 0 sccm, an Al2O3 film layer is formed on the substrate, and the refractive index of the Al2O3 film layer is 1.65.

[0091] Specifically, when forming a structure in which high-refractive-index AlOxNy film layers and low-refractive-index AlOxNy film layers are alternately stacked on a substrate through one preparation process, it can be directly achieved by controlling the flow rates of oxygen and nitrogen. For example, when it is necessary to form an AlN film layer with a certain thickness on the substrate, only by controlling the controller to introduce N2 without introducing O2, an AlN film layer can be formed on the substrate. When it is necessary to form an Al2O3 film layer on the AlN film layer, the introduction of N2 can be closed by the controller and the introduction of O2 can be controlled, and an Al2O3 film layer can be formed on the AlN film layer. By analogy, an antireflection film in which high-refractive-index AlN film layers and low-refractive-index Al2O3 film layers are alternately stacked can be prepared in one time without changing the types of raw materials and / or gases. In the existing antireflection film with an alternating stacking structure, the high-refractive-index film layer is generally a TiN2 film layer, and the low-refractive-index film layer is generally a SiO2 film layer. During the preparation of the antireflection film, the raw material needs to be changed from Ti monomer to Si monomer, and changing the raw material of the film layer requires increasing the preparation process. At the same time, the gas needs to be changed from N2 to O2, and changing the gas also requires increasing the preparation process. Therefore, there are multiple processes in the entire preparation process of the antireflection film and it cannot be completed through one process, resulting in huge costs.

[0092] Table 1 shows the parameters of the alternating stacking structure in the antireflection film. As shown in Table 1, the antireflection film has a total of 12 layers and is composed of high-refractive-index AlN film layers and low-refractive-index Al2O3 film layers in an alternating stacking manner.

[0093] Table 1

[0094]

[0095]

[0096] Among them, the material of the first layer is AlN, with a refractive index of 1.98, and the thickness of the first film layer is 25.25 nm; the material of the second layer is Al2O3, with a refractive index of 1.65, and the thickness of the second film layer is 25.18 nm; the material of the third layer is AlN, with a refractive index of 1.98, and the thickness of the third film layer is 77.18 nm; the material of the fourth layer is Al2O3, with a refractive index of 1.65, and the thickness of the fourth film layer is 57.58 nm; the material of the fifth layer is AlN, with a refractive index of 1.98, and the thickness of the fifth film layer is 6.28 nm; the material of the sixth layer is Al2O3, with a refractive index of 1.65, and the thickness of the sixth film layer is 90.94 nm; the material of the seventh layer is AlN, with a refractive index of 1.98, and the thickness of the seventh film layer is 73.92 nm; the material of the eighth layer is Al2O3, with a refractive index of 1.65, and the thickness of the eighth film layer is 35.34 nm; the material of the ninth layer is AlN, with a refractive index of 1.98, and the thickness of the ninth film layer is 18.49 nm; the material of the tenth layer is Al2O3, with a refractive index of 1.65, and the thickness of the tenth film layer is 90.23 nm; the material of the eleventh layer is AlN, with a refractive index of 1.98, and the thickness of the eleventh film layer is 67.26 nm; the material of the twelfth layer is Al2O3, with a refractive index of 1.65, and the thickness of the twelfth film layer is 80.39 nm.

[0097] It should be noted that the film layer structure and parameters in Table 1 are only examples, and this application can prepare an alternately stacked film layer structure with different refractive indexes according to actual needs, where the refractive index of the film layer can be between 1.65 and 1.98.

[0098] According to the antireflection principle: when a light beam is incident on the interface between two media, reflection and refraction will occur. If an optical thin film with a thickness of one-quarter wavelength is coated on the interface, the reflected light can be made to interfere destructively with the incident light, thereby reducing reflection. Therefore, when the equivalent optical path of the entire antireflection film is an odd multiple of λ / 4, the function of low reflection in the used wavelength band can be achieved. Among them, λ is the wavelength of the light in the used wavelength band, and the equivalent optical path = n1*d1 + n2*d2 +... + nx*dx, where x is the number of layers and n is the refractive index. By taking the visible light wavelength band as the used wavelength band and according to the above formula for calculating the equivalent optical path, the number of layers and thickness of the AlN film layer and the Al2O3 film layer can be reasonably set. As shown in Table 1, an antireflection film with a reflectivity lower than <1% in the visible light wavelength band can be formed on the substrate, as Figure 4 shown.

[0099] In another optional embodiment of this application, a micro-nano structured antireflection film is prepared on a glass substrate. As Figure 5As shown, first, an AlOxNy film layer is prepared on a glass substrate by magnetron sputtering. Using aluminum monomer as the target, oxygen and nitrogen are introduced into the ICP ion source, and oxygen and nitrogen are activated, so that the ionized oxygen ions and nitrogen ions react chemically with the aluminum monomer. When the power of the ICP ion source is 1 kW, the flow rate of the introduced oxygen is controlled to be 10 sccm and the flow rate of the introduced nitrogen is 40 sccm by MFC, and an AlO1N2 film layer 320 with a thickness of 120 nm is formed on the glass substrate 310. Then, a micro-nano structured antireflection film is prepared on the glass substrate by water bath. Among them, the AlO1N2 film layer 320 is heated by water bath with 95°C hot water, and the AlO1N2 film layer undergoes a hydrolysis reaction in the 95°C hot water, and a 365-nm micro-nano structure is self-grown on the glass substrate 310 as the micro-nano structured antireflection film 330, as Figure 6 shown.

[0100] According to the antireflection principle: The principle of the moth-eye antireflection is adopted, and a layer of micro-nano structure is attached to the substrate. This surface micro-nano structure cannot be recognized because its size is much lower than the visible light band, so the refractive index at the interface can change continuously and smoothly along the depth direction of the moth-eye structure. In this way, the light reflection caused by the sharp change in refractive index is greatly reduced, and the film layer thus has an extremely low reflection coefficient. As Figure 7 shown, according to the above antireflection principle, the prepared micro-nano structured antireflection film 330 has an ultra-low reflectivity in the visible light band, and its reflectivity is less than or equal to ≤0.1%.

[0101] In another alternative embodiment of the present application, a micro-nano structured antireflection film is prepared on the substrate. First, an AlOxNy film layer is prepared on the substrate by electron beam evaporation. As Figure 8 , using aluminum monomer 440 as the raw material, the aluminum monomer is bombarded by an electron beam to excite aluminum atoms. Oxygen and nitrogen are introduced into the ion source 430, and oxygen and nitrogen are activated, so that the ionized oxygen ions and nitrogen ions react chemically with the excited aluminum atoms. The current of the electron beam emitted by the electron gun is controlled to be 200±10 mA. When the power of the ion source 430 is 1 kW, the flow rate of the introduced oxygen is controlled to be 0 sccm and the flow rate of the introduced nitrogen is 100 sccm by the controller, and an AlN film layer 420 with a thickness of 110 nm is formed on the substrate 410. Then, a micro-nano structured antireflection film is prepared on the substrate by water bath. Among them, the AlN film layer 420 is heated by water bath with 65°C hot water, and the AlN film layer 420 undergoes a hydrolysis reaction in the 65°C hot water, and a 338-nm micro-nano structure is self-grown on the substrate 410 as the micro-nano structured antireflection film, as Figure 9 shown.

[0102] According to the anti-reflection principle, the prepared anti-reflection film with micro-nano structure has an ultra-low reflectivity in the visible light band, and its reflectivity is less than or equal to ≤0.1%.

[0103] In another optional embodiment of the present application, an AlOxNy film layer is prepared on a substrate by chemical vapor deposition. Among them, aluminum monomer is used as a raw material, and oxygen and nitrogen are activated by heating, plasma, or a combination of both, so that the activated oxygen ions and nitrogen ions react chemically with the aluminum monomer to form an AlOxNy film layer on the substrate. By controlling the flow ratio of oxygen to nitrogen, the refractive index of the AlOxNy film layer formed on the substrate can be adjusted.

[0104] The embodiment of the present application also provides an optical element, which includes: a light-transmitting substrate and an optical thin film. Among them, the optical thin film is coated on the light-transmitting substrate, and the optical thin film includes a film layer prepared by using the method for preparing a film layer with adjustable refractive index according to the above embodiment of the present application.

[0105] The above specific embodiments do not constitute a limitation to the protection scope of the present disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. An optical thin film, characterized in that, The optical thin film includes at least one monomer or monomer compound and at least two gaseous elements, and is prepared by a single process.

2. The optical thin film according to claim 1, characterized in that, The refractive index of the optical thin film can be adjusted by adjusting the flow rate ratio of the at least two gaseous elements in the single process.

3. The optical thin film according to claim 1, characterized in that, The monomer includes one of aluminum, boron, and silicon monomers or one of the complexes of aluminum, boron, and silicon.

4. The optical thin film according to claim 2, characterized in that, The refractive index of the optical thin film can be adjusted within the range of 1.65 to 1.

98.

5. The optical thin film according to claim 1, characterized in that, The optical thin film includes an AlOxNy thin film, where x and y respectively refer to the ratio of the number of O and N atoms to one Al atom, and are respectively ≥ 0 and cannot be 0 at the same time.

6. The optical thin film according to claim 5, characterized in that, In the AlOxNy, x / y satisfies: x / y = 2.03K * [exp(F1 / 1.44F2) - 1]; where K is the power of the ion source; F1 is the volume flow rate of oxygen that chemically reacts with the aluminum monomer or the aluminum compound; and F2 is the volume flow rate of nitrogen that chemically reacts with the aluminum monomer or the aluminum compound.

7. The optical thin film according to claim 6, characterized in that, K is 0 to 6 kW, F1 is 0 to 300 sccm, and F2 is 0 to 300 sccm.

8. The optical thin film according to claim 6 or 7, characterized in that, The refractive index n of the AlOxNy thin film satisfies:

9. A method for preparing a film layer with adjustable refractive index, characterized in that, including: providing a monomer or a compound of the monomer on a substrate; reacting the monomer or the compound of the monomer with at least two gases to form a target film layer on the substrate, wherein, during the reaction process, by adjusting the flow rate ratio of the at least two gases, the target film layer with adjustable refractive index is formed on the substrate.

10. An optical element, characterized in that, including: a light-transmitting substrate; and an optical thin film, the optical thin film is coated on the light-transmitting substrate and includes a film layer prepared by the method for preparing a refractive index adjustable film layer according to claim 9.

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