Surface structure and preparation method thereof

Abstract

The invention provides a surface structure and a preparation method thereof. The preparation method comprises an annealing process and a deposition process. Wherein the annealing process comprises the following steps of: arranging a base material of which the surface is covered with a metal film in a variable-temperature environment; under the condition that the temperature of the variable temperature environment reaches a first temperature, after the first temperature is kept for a first duration, cooling the base material of which the surface is covered with the metal film to a second temperature so as to form a first structure in the metal film; wherein the deposition process comprises the steps that under the condition that the size of the formed first structure reaches a target size, etching is carried out based on the first structure, so that a second structure complementary to the first structure is formed on the base material. The metal mask is formed through a coating-annealing process, and mask preparation is realized without photoetching, so that an effective solution is provided for solving the problems that a traditional optical device is easy to pollute in a complex environment, the optical performance is easy to degrade and the like.

Description

Technical Field

[0001] The present application relates to the field of nanotechnology, and in particular to a surface structure and a preparation method thereof. Background Art

[0002] With the rapid development of nanotechnology, the application of micro- and nanostructures in the optical field is becoming increasingly widespread. In particular, devices such as metasurfaces offer powerful optical field manipulation capabilities. However, traditional micro- and nanostructured devices face numerous challenges in practical applications, such as insufficient stability in complex environments, susceptibility to contamination, and interference with optical performance. These issues limit the application of various precision optical devices in these complex environments.

[0003] Existing surface nanostructuring techniques typically use photolithography to create a mask, followed by etching to transfer the nanopattern to the surface to be processed. Due to limitations in the fabrication process, these methods are unable to achieve nanostructuring on large areas or curved surfaces. Furthermore, these methods often struggle to simultaneously meet the requirements for optical performance and environmental adaptability. Summary of the Invention

[0004] In view of this, the purpose of the embodiments of the present application is to provide a method for preparing a surface structure to improve the many challenges faced by traditional micro-nanostructure devices in the prior art in practical applications, such as insufficient stability in complex environments, susceptibility to contamination, and susceptibility to interference in optical properties.

[0005] The preparation method includes: an annealing process and a deposition process; wherein the annealing process includes: placing a substrate whose surface is covered with a metal film in a variable temperature environment; when the temperature of the variable temperature environment reaches a first temperature, maintaining the first temperature for a first period of time, and then cooling the substrate whose surface is covered with the metal film to a second temperature to form a first structure in the metal film; wherein the deposition process includes: when the size of the formed first structure reaches a target size, etching based on the first structure to form a second structure complementary to the first structure on the substrate.

[0006] In the above-mentioned implementation process, the preparation method achieves the optimization and functionalization of the metal film structure by controlling the two key steps of annealing and deposition. Specifically, the annealing process relies on the physical and chemical changes of the metal film at different temperatures through gradual changes in temperature and time control to induce the metal film to form a first structure with specific dimensions. The substrate with the metal film on the surface is placed in a variable temperature environment and maintained for a certain period of time after reaching the first temperature, so that the microstructure inside the metal film reaches the required size and shape and has a certain stability. During the deposition process, when the size of the first structure reaches the target size, a second structure complementary to the first structure is etched on the substrate. The annealing process provides the necessary thermodynamic conditions for the metal film to form a stable microstructure; while the deposition process converts these structures into surface morphologies with practical application value through etching technology. By optimizing parameters such as temperature, time and etching conditions, the efficiency of the preparation method and the performance of the finished product can be significantly improved, thereby meeting the needs of specific application scenarios.

[0007] Optionally, the preparation method also includes: a metal film preparation process; wherein the metal film preparation process includes: cleaning the substrate with a plurality of cleaning solvents and then drying the substrate; when the substrate is completely dried, plating a metal film on the substrate using a coating process; wherein the metal can be one of gold, silver, and platinum, and the thickness of the metal film is 3nm to 10nm; wherein the coating process includes physical vapor deposition, chemical vapor deposition, electroplating, solution deposition and spraying.

[0008] In the above implementation process, the process of preparing the metal film ensures that the cleanliness and dryness of the substrate are the key to the adhesion performance of the metal film. By using a variety of cleaning solvents (such as acetone, isopropyl alcohol or deionized water) to clean the substrate, organic pollutants, oxides or other impurities on the surface can be effectively removed. Subsequently, the dried substrate ensures the cleanliness and dryness of its surface, providing ideal conditions for subsequent coating. For example, physical vapor deposition (such as magnetron sputtering or evaporation coating) can achieve high-precision and uniform metal film deposition, which is suitable for scenarios with high requirements for thickness control; while chemical vapor deposition is suitable for uniform coverage of complex-shaped substrates. The thickness of the metal film is controlled in the range of 3nm to 10nm to ensure the stability and controllability of the structure formation during subsequent annealing.

[0009] Optionally, the coating process is magnetron sputtering coating; the power of the magnetron sputtering coating is maintained within a low power range, the protective gas is an inert gas, and the working gas pressure during the coating process is set within a low pressure range.

[0010] In the above-mentioned implementation process, the coating process uses magnetron sputtering coating to achieve high-precision and uniform metal film deposition. The power of magnetron sputtering coating is kept within a low power range, which helps to reduce the bombardment energy of metal ions, thereby avoiding damage to the surface of the substrate, while ensuring that the deposition of the metal film is more uniform and dense. During the coating process, an inert gas is used as a protective gas to prevent the metal from being oxidized during the deposition process, while providing a stable plasma environment to ensure uniform sputtering and deposition of metal particles. The working gas pressure during the coating process is set within a low pressure range. The low pressure environment helps to reduce the collision frequency of gas molecules, thereby improving the flight efficiency and deposition uniformity of metal ions. It also helps to control the thickness of the metal film, forming a high-quality metal film with a thickness of 3nm to 10nm on the surface of the substrate.

[0011] Optionally, when the temperature of the variable temperature environment reaches a first temperature, the first temperature is maintained for a first period of time, and then the substrate with the surface covered with a metal film is cooled to a second temperature, comprising: placing the substrate with the surface covered with a metal film in a high-temperature annealing furnace, and heating it to the first temperature at a constant heating rate of 20°C / min; while maintaining the substrate in the environment of the first temperature for at least 30 minutes, cooling it to the second temperature and taking out the substrate; wherein the first temperature ranges from 600 to 1000°C, and the second temperature is consistent with room temperature.

[0012] In the above implementation process, the substrate with the metal film covered on the surface is placed in a high-temperature annealing furnace, and the temperature is gradually increased to the first temperature while maintaining a heating rate of 20°C / min. A slower heating rate helps to reduce the thermal stress inside the metal film and avoid structural defects or film peeling caused by excessive temperature gradients. At the same time, gradual heating can also ensure that the difference in thermal expansion coefficient between the substrate and the metal film is buffered, thereby improving the adhesion of the metal film. After reaching the first temperature (ranging from 600 to 1000°C), the substrate is maintained at this temperature for at least 30 minutes. The transformation of the metal film to the first structure (such as a metal island structure) during the heat treatment process is achieved by the principle of surface dewetting. After the temperature rises, the metal film originally attached to the substrate will cluster into a spherical shape along the cracks of the metal film itself due to the performance tension. Among them, the temperature mainly affects the surface tension of the metal in a high temperature environment, and the holding time mainly affects the degree of formation of the nano-island particles. By maintaining a high temperature environment, it is possible to ensure that the microstructure inside the metal film achieves the required stability and uniformity, thereby forming a first structure with a specific size. After the high temperature is maintained, the substrate is cooled to a second temperature (similar to room temperature). The cooling process generally adopts a natural cooling or a controlled cooling rate method to avoid internal stress concentration or structural defects of the metal film caused by rapid cooling.

[0013] Optionally, the method further includes: if the size of the first structure does not meet the target size, repeating the annealing process until the size of the first structure meets the target size.

[0014] In the above implementation process, when it is detected that the size of the first structure has not reached the target size, the substrate needs to be placed in a variable temperature environment again and the annealing process needs to be performed again. By repeated annealing, the microstructure inside the metal film is further optimized, so that the size of the first structure gradually approaches and eventually reaches the target size, ensuring that the second structure formed in the subsequent deposition process can meet the design requirements. After the initial annealing, the size of the first structure is tested to determine whether it meets the target size. If the size does not meet the requirements, the annealing parameters are appropriately adjusted according to the size and direction of the size deviation. For example, if the size of the first structure is too large, the number of coating-annealing processes can be appropriately increased to control the size of the structure. The substrate is placed in the high-temperature annealing furnace again, and the annealing process is performed according to the adjusted parameters, and the heating, insulation and cooling steps are repeated until the size of the first structure reaches the target size. When the size of the first structure reaches the target size through repeated annealing, the deposition process can proceed smoothly.

[0015] Optionally, etching is performed based on the first structure to form a second structure complementary to the first structure on the substrate, including: using the first structure as a mask and preparing the second structure on the substrate using a dry etching process; wherein the dry etching process can be one of reactive ion etching, ion beam etching, and high-density plasma etching.

[0016] In the above implementation process, a stable and dimensionally determined first structure is used as a mask, and its protective effect on the substrate is utilized to achieve pattern transfer to the substrate. The quality and stability of the mask directly affect the etching effect, so it is necessary to ensure that the first structure does not deform or damage during the etching process. A dry etching process with high precision, high selectivity and good directionality is adopted, such as reactive ion etching (RIE) that achieves etching through the synergistic effect of chemical reaction and physical bombardment, ion beam etching (IBE) that directly bombards the surface of the substrate with a high-energy ion beam, or high-density plasma etching (HDP) that etches in a high-density plasma environment, which can ensure that a second structure complementary to the first structure is formed on the substrate.

[0017] Optionally, in the dry etching process, the etching radio frequency power adopts low-power etching, the etching reaction gas is a fluorine-based gas, the ambient pressure is maintained at a low-pressure environment, and the etching is performed at a flow rate not higher than 20 sccm.

[0018] In the above implementation process, the use of a low-power radio frequency (RF) power source for etching helps reduce damage to the substrate and the first structure while ensuring the uniformity and directionality of the etching process. Lower power can avoid structural deformation or damage caused by high-energy ion bombardment, thereby improving the precision of the second structure. Fluorine-based gases (such as CF4, SF6, CHF3, etc.) are selected as etching reaction gases. They can undergo efficient chemical reactions with the metal film in a plasma environment to form volatile etching products, thereby achieving highly selective and efficient etching. The etching process is carried out in a low-pressure environment, which helps reduce the collision frequency of gas molecules, thereby improving the transmission efficiency of the etching gas and the uniformity of the reaction. Low pressure conditions can also enhance the stability of the plasma and the directionality of the etching, ensuring the precision of the formation of the second structure. The flow rate of the etching reaction gas is controlled within a range of no more than 20 sccm (standard cubic centimeters per minute), which helps maintain the stability of the etching environment and the uniform distribution of the gas, and avoids gas turbulence or uneven reaction caused by excessive flow. By controlling the flow rate, the etching rate and selectivity can be further optimized. Low-power etching and a low-pressure environment ensure uniformity and directionality in the etching process, enabling high-precision formation of the secondary structure. The selection and flow control of fluorine-based gases further improves the selectivity and efficiency of the etching, enhancing the repeatability and stability of the etching process.

[0019] Optionally, the deposition process further comprises: performing a fluorination treatment when the pattern formed by the first structure is transferred to the substrate; wherein the fluorination treatment is one of vapor deposition or immersion in a fluorine-containing solution.

[0020] In the above implementation process, the fluorination treatment aims to form a fluoride protective layer on the surface of the second structure, which can reduce its surface energy, increase its hydrophobicity, etc., thereby improving its performance in specific application scenarios. According to the specific application requirements and material properties, a method of vapor deposition or immersion in a fluorine-containing solution is selected for fluorination treatment. Vapor deposition is to place the substrate in a vapor deposition device, introduce a fluorine-containing gas (such as hydrogen fluoride, carbon tetrafluoride, etc.), and under specific temperature and pressure conditions, allow the fluorine-containing gas to react with the surface of the second structure to form a uniform fluoride protective layer. During the vapor deposition process, parameters such as gas flow, deposition time and temperature need to be controlled to ensure the thickness and quality of the fluoride layer.

[0021] Optionally, when the pattern formed by the first structure is transferred to the substrate, the substrate is immersed in a fluorine-containing solution; wherein the fluorine-containing solution is a mixed solution of a fluorosilane solution and alcohol.

[0022] In the above implementation process, after etching the first structure and successfully transferring the pattern to the substrate to form the second structure, the substrate is initially cleaned to remove any impurities and contaminants that may have remained during the etching process, ensuring a clean surface. Fluorination treatment forms a uniform fluoride protective layer on the surface of the second structure, significantly improving its chemical stability and corrosion resistance, reducing its surface energy, and increasing its hydrophobicity, thereby improving its performance in specific application scenarios.

[0023] The present application also provides a surface structure, which includes a first structure and a second structure; the first structure and the second structure are arranged on a substrate; the preparation process of the first structure includes: placing the substrate whose surface is covered with a metal film in a variable temperature environment; when the temperature of the variable temperature environment reaches a first temperature, maintaining the first temperature for a first time, cooling the substrate whose surface is covered with a metal film to a second temperature to form a first structure in the metal film; the preparation process of the second structure includes: when the size of the formed first structure reaches a target size, etching based on the first structure to form a second structure complementary to the first structure on the substrate.

[0024] In the above-mentioned process, the surface structure preparation method realizes the control of the first and second structures through heat treatment and etching techniques. The formation of this structure not only improves the performance of the material, but also enhances its versatility and adaptability, making it have a wide range of application potential in optoelectronic devices, catalysts, sensors and energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. It should be understood that the following drawings only show certain embodiments of the present application 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 creative work.

[0026] Figure 1 Schematic diagram of the preparation method of the surface structure provided in the embodiment of the present application;

[0027] Figure 2 A schematic diagram of the metal film preparation process provided in an embodiment of the present application;

[0028] Figure 3 A schematic diagram of the annealing process provided in an embodiment of the present application;

[0029] Figure 4 A schematic diagram of a deposition process provided in an embodiment of the present application;

[0030] Figure 5 This is an electron microscope scan of metal nanoparticles on the surface of the substrate during the preparation process provided in the examples of this application;

[0031] Figure 6 This is an electron microscope scanning image of the nano-columnar structure after dry etching on the substrate surface provided in the embodiment of the present application;

[0032] Figure 7 This is a diagram showing the anti-reflection effect of the surface nanostructure provided in the embodiment of the present application;

[0033] Figure 8 This is a test chart of the surface hydrophobic effect and scratch resistance. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of them. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the embodiments of the present application.

[0035] The embodiments of the present application provide a method for preparing a surface structure, which can be applied to improve the surface performance of various devices such as precision optical devices.

[0036] See also Figure 1 , Figure 1 This is a schematic diagram of a method for preparing a surface structure provided in an embodiment of the present application. The aforementioned preparation method includes: an annealing process and a deposition process.

[0037] The annealing process includes: placing a substrate whose surface is covered with a metal film in a variable temperature environment; when the temperature of the variable temperature environment reaches a first temperature, maintaining the first temperature for a first period of time, and then cooling the substrate whose surface is covered with the metal film to a second temperature to form a first structure in the metal film; the deposition process includes: when the size of the formed first structure reaches a target size, etching based on the first structure to form a second structure complementary to the first structure on the substrate.

[0038] In the above implementation process, the annealing process is to place the substrate whose surface is covered with a metal film in a variable temperature environment, and gradually increase the temperature to reach a first temperature. Maintaining the first time at the first temperature allows the reorganization and optimization of the microstructure inside the metal film. The substrate is then cooled to a second temperature to promote the formation of a specific first structure in the metal film. The formation of the first structure depends on the effect of temperature changes on the surface tension of the metal film, thereby achieving the desired physical or chemical properties. When the size of the first structure reaches the predetermined target size, the deposition process begins. The first structure is processed using etching technology, and part of the material is removed by chemical or physical methods to form a second structure complementary to the first structure on the substrate. The second structure usually forms a complementary relationship with the first structure in function or geometry to meet specific application requirements.

[0039] See also Figure 2 , Figure 2 Schematic diagram of the metal film preparation process provided in an embodiment of the present application.

[0040] The preparation method also includes: a metal film preparation process; wherein the metal film preparation process includes: cleaning the substrate with a plurality of cleaning solvents and then drying the substrate; when the substrate is completely dried, plating a metal film on the substrate using a coating process; wherein the metal can be one of gold, silver, and platinum, and the thickness of the metal film is 3nm to 10nm.

[0041] In the above implementation process, during the preparation of the metal film, first, the substrate is cleaned with a variety of cleaning solvents to remove impurities and contaminants on the surface to ensure the uniformity and adhesion of the subsequent coating. After cleaning, the substrate needs to be dried to eliminate residual moisture or solvents. When the substrate is completely dry, a layer of metal film is plated on the surface of the substrate using a coating process. The metal can be selected from gold, silver or platinum, and the specific choice depends on the needs of the target application. The thickness of the metal film is controlled in the range of 3nm to 10nm to meet the precision requirements of micro-nano structure preparation.

[0042] In one embodiment of the present application, the substrate is cleaned using acetone, alcohol, deionized water, etc. to remove impurities and contaminants on the surface of the substrate. After cleaning, the substrate is dried using an inert gas to eliminate residual moisture or solvent.

[0043] Optionally, the coating process includes one of physical vapor deposition (PVD), chemical vapor deposition (CVD), electroplating, solution deposition or spraying.

[0044] In one embodiment of the present application, when the substrate is completely dry, a metal film is coated on the surface of the substrate using a magnetron sputtering coating process. The metal film thickness is 3 to 10 nm, and the metal can be gold, silver, platinum, etc. The power of the magnetron sputtering coating is kept within a low power range to ensure uniform deposition of the metal film and avoid damage to the substrate. An inert gas is used as a protective gas to prevent the metal film from being oxidized or contaminated during the coating process. Inert gas can also improve sputtering efficiency and film quality. The working gas pressure during the coating process is set within a low pressure range, set to 0.1 Pa to 10 Pa, which helps to reduce collisions between gas molecules and improve the flight distance and deposition efficiency of the sputtered particles.

[0045] In another embodiment of the present application, the power of the magnetron sputtering process is set to 20W and the gas pressure is set to 0.2Pa, and the substrate with the metal film coated on the surface is placed in a high-temperature annealing furnace with argon as the protective gas, so that the metal film on the surface of the substrate is clustered into nanoparticles with a metal island structure, that is, the first structure.

[0046] Alternatively, the coating process may be other physical vapor deposition methods, including ion plating, vacuum evaporation, etc.

[0047] In one embodiment of the present application, ion plating is used, the reaction gas pressure is set to 0.2 Pa, the substrate negative bias voltage is set between 100 V and 500 V, the deposition time is between 0.5 and 5 hours, and the vacuum degree is generally 10 -1 to 10 -4 Between Pa.

[0048] See also Figure 3 , Figure 3 Schematic diagram of the annealing process in the embodiment of the present application.

[0049] Optionally, when the temperature of the variable temperature environment reaches a first temperature, the first temperature is maintained for a first period of time, and then the substrate with the metal film covered on the surface is cooled to a second temperature, including: placing the substrate with the metal film covered on the surface into a high-temperature annealing furnace, maintaining a heating rate of 20°C / min, and heating it to the first temperature; while maintaining the substrate in an environment at the first temperature for a first period of time, cooling it to the second temperature and taking out the substrate; wherein the first temperature ranges from 600 to 1000°C, and the second temperature is consistent with room temperature.

[0050] In the above implementation process, after the preparation of the metal film is completed, the substrate with the surface covered with the metal film is placed in a high-temperature annealing furnace, the heating rate is kept constant at 20°C / min, and the temperature is gradually raised to the first temperature to ensure the uniform change of the internal structure of the metal film and avoid damage to the film layer caused by rapid heating. The first temperature is controlled in the range of 600 to 1000°C to achieve metal masks of different geometric sizes for different functional implementations. Maintain at the first temperature for at least a first time to control the surface tension of the metal in a high temperature environment, so as to improve the uniformity of the metal film clustering into a granular structure along the crack direction, thereby achieving the desired physical or chemical properties. After the insulation is completed, the substrate is cooled to the second temperature. The cooling process usually adopts natural cooling or controls the cooling rate to ensure that a specific first structure is formed in the metal film. The formation of the first structure depends on the effect of temperature change on the surface tension of the metal to achieve the desired physical or chemical properties.

[0051] In one embodiment of the present application, a substrate whose surface is covered with a metal film is placed in a high-temperature annealing furnace, and the heating rate is maintained at 20°C / min to 800°C; when the ambient temperature reaches 800°C, this temperature is maintained for 30 minutes. After it is cooled to room temperature, the substrate with nanoparticles having a stable metal island structure formed on the surface is taken out. At this time, the metal film on the surface of the substrate is clustered into nanoparticles with a metal island structure.

[0052] Optionally, the method further includes: if the size of the first structure does not meet the target size, repeating the annealing process until the size of the first structure meets the target size.

[0053] In the above implementation process, if the size of the first structure does not meet the target size, the annealing process needs to be repeated until the size of the first structure reaches the expected size. Each time the annealing is repeated, the annealing parameters (such as the first temperature, the holding time, the heating rate, etc.) can be appropriately adjusted to optimize the size of the first structure. After each annealing, the size of the first structure is measured using a measuring tool (such as a scanning electron microscope, an atomic force microscope, etc.) to ensure that it meets the target size requirements. The number of repeated annealing depends on the material properties and the accuracy requirements of the target size. Usually 2 to 5 annealings are required to achieve the expected effect. When the size of the first structure reaches the target size, the deposition step is started.

[0054] Optionally, the conditions (such as temperature, time, etc.) of the repeated annealing may be the same as those of the initial annealing, or may be appropriately adjusted according to the difference between the current size of the first structure and the target size.

[0055] In the aforementioned implementation process, it can be seen that after the above-mentioned operation, the metal film on the substrate surface first forms a nano-island structure. The size of the island structure is adjusted. If the size of the first structure does not meet the target size, the coating-annealing process is repeated until the first structure meets the target size, thereby increasing the aspect ratio of the metal mask. The nanostructure can be a metal nanocone or metal nanopillar structure to achieve an anti-reflection effect. Because the above process uses metal as a mask rather than traditional photolithography, this method has the ability to produce nanostructures on large-area quartz surfaces, which has obvious advantages in the preparation of large-diameter devices.

[0056] In one embodiment of the present application, quartz is used as the substrate and the above-mentioned surface structure preparation method is used to construct a metal mask with a large aspect ratio (nanostructure height: top surface diameter ≥ 3). The height of the nanostructure ranges from 200 to 1000 μm, the diameter ranges from 10 to 200 nm, and the filling ratio is >60%.

[0057] In one embodiment of the present application, as the number of coating-annealing times increases, the size of the metal mask changes as follows: one cycle of coating-annealing process can make its diameter 20 to 100 nm and its aspect ratio 0.1 to 0.5; three cycles of coating-annealing process can make its diameter 30 to 150 nm and its aspect ratio 1 to 3; seven cycles of coating-annealing process can make its diameter 50 to 200 nm and its aspect ratio 3 to 10.

[0058] In one embodiment of the present application, the nanostructure has a diameter in the range of 100 to 200 nm, an aspect ratio in the range of 1 to 3, and a structure filling ratio of 60 to 70%, which can achieve an average transmittance enhancement of 2%.

[0059] In one embodiment of the present application, the nanostructure size is in the range of 50 to 100 nm, the aspect ratio is in the range of 3 to 5, and the structure filling ratio is 70 to 80, which can achieve an average transmittance enhancement of 4%.

[0060] In one embodiment of the present application, the nanostructure has a diameter in the range of 10 to 100 nm, an aspect ratio in the range of 5 to 10, and a structure filling ratio of 70 to 90%, which can achieve an average transmittance enhancement of 6%.

[0061] See also Figure 4 , Figure 4 A schematic diagram of the deposition process provided in an embodiment of the present application.

[0062] Optionally, etching is performed based on the first structure to form a second structure complementary to the first structure on the substrate, including: using the first structure as a mask and preparing the second structure on the substrate using a dry etching process; wherein the dry etching process can be one of reactive ion etching, ion beam etching, and high-density plasma etching.

[0063] In the above implementation process, the first structure is used as a mask, and a second structure complementary to the first structure is prepared on the substrate using a dry etching process. The specific dry etching process can be one of reactive ion etching (RIE), ion beam etching (IBE) or high-density plasma etching (HDP). Reactive ion etching (RIE) achieves high-selectivity and high-resolution etching through a combination of chemical reaction and physical bombardment, and can form complex geometric structures. Ion beam etching (IBE) uses a high-energy ion beam to directly bombard the surface of the material to achieve physical etching, which has the characteristics of high directionality and low damage and is suitable for applications with high precision requirements. High-density plasma etching (HDP) uses high-density plasma to achieve efficient etching, with a high etching rate and good uniformity, and is suitable for large-area and deep-hole etching. After removing part of the material by etching, a second structure that is complementary to the first structure in function or geometry is formed on the substrate to meet specific application requirements.

[0064] In one embodiment of the present application, a first structure is used as a mask, and a second structure complementary to the first structure is prepared on a substrate using a dry etching process. Low-power etching is used to reduce damage to the substrate and the metal film and ensure the fineness of the etching. Fluorine-based gases (such as CF4, SF6, etc.) are used, and these gases chemically react with the material in a plasma environment to achieve efficient etching. A low-pressure environment (typically 0.1Pa to 10Pa) is maintained to ensure that the motion trajectory of the gas molecules is more straight, reduce collisions, and improve the accuracy and efficiency of etching. Etching is performed at a flow rate of not more than 20sccm to ensure the stability and uniformity of the gas supply and avoid uneven etching due to excessive flow. After removing part of the material by etching, a second structure complementary to the first structure is formed on the substrate, which usually forms a complementary relationship with the first structure in function or geometry to meet specific application requirements. In one embodiment of the present application, in the dry etching process, the etching RF power adopts low-power etching, the etching reaction gas is a fluorine-based gas, the ambient pressure is maintained at a low-pressure environment, and etching is performed at a flow rate not higher than 20 sccm.

[0065] In another embodiment of the present application, the reactive ion etching reaction gas is tetrafluoromethane with a flow rate of 20 sccm, the gas pressure is controlled to be 0.2 Pa, and the radio frequency power is set to 40W.

[0066] In another embodiment of the present application, ion beam etching is used, the ion beam energy range is set to 300 to 500 eV, and the ion current beam density is 2 to 8 mA / cm 2Argon is used as the working gas, the working pressure is set at 10 to 50 mTorr (1 torr = 133.3 Pa), and the etching rate is 10 to 50 nm / min. In another embodiment of the present application, high-density plasma etching is used, the ICP power is set to 500 to 1500 W, the bias power is 50 to 300 W, and the etching gas is a chlorine-based gas such as CF4, C4F8, SF6, or CHF3. The pressure is controlled at 1 to 10 mTorr, the flow rate is 20 to 100 sccm, and the etching rate is maintained in the range of 100 to 500 nm / min.

[0067] Optionally, determine the time required to reach the target etching depth through preliminary experiments or simulation calculations. Etching times that are too short can result in incomplete etching, while those that are too long can cause over-etching, affecting structural accuracy. During the etching process, monitor the etching rate in real time to ensure it remains stable within the expected range.

[0068] Optionally, the deposition process further includes: performing a fluorination treatment when the pattern formed by the first structure is transferred to the substrate; wherein the fluorination treatment is one of vapor deposition or immersion in a fluorine-containing solution.

[0069] In the above implementation process, when the pattern formed by the first structure is transferred to the substrate, a fluorination treatment is performed to enhance the stability and durability of the pattern. The fluorination treatment can be a vapor deposition or immersion in a fluorine-containing solution. A layer of fluoride film is deposited on the surface of the substrate by vapor deposition technology, while reducing the surface energy of the surface nanostructure. Fluorosilane solution generally has good film-forming properties and stability and can form a strong chemical bond with the surface of the substrate. The cleaned substrate is immersed in the prepared fluorine-containing mixed solution, and the temperature is controlled within a certain range to ensure the activity and reaction rate of the fluorosilane.

[0070] In one embodiment of the present application, after etching is performed based on the first structure and the pattern is successfully transferred to the substrate to form the second structure, the substrate is preliminarily cleaned to remove impurities and contaminants that may remain during the etching process, providing a clean surface for fluorination treatment. A mixed solution of fluorosilane solution and alcohol is prepared. The concentration of the mixed solution is generally controlled at 1% to 5% (volume ratio). The substrate is immersed in a fluorine-containing solution to allow the fluoride to react chemically with the surface of the substrate to form a stable fluoride layer. The fluorinated sample is heat-treated in a constant temperature box at 80°C for 2 hours to enhance the stability of the surface chemical structure. A uniform fluoride layer is formed on the surface of the substrate, while reducing the surface energy and improving the hydrophobicity. After the immersion treatment is completed, the substrate is taken out and directly heat-treated in a constant temperature box to solidify the fluoride layer. This is followed by a drying treatment, such as nitrogen drying or vacuum drying.

[0071] During this process, it's crucial to ensure uniform mixing of the fluorosilane solution and alcohol to avoid uneven treatment due to solution stratification. By adjusting the solution concentration, immersion time, and temperature, the thickness of the fluoride layer can be controlled, forming a protective fluoride layer on the surface of the second structure, reducing its surface energy.

[0072] Alternatively, the first structure after etching is removed by soaking in aqua regia and piranha solution for 10 minutes. Both solutions are standard solutions and do not need to specify the ratio.

[0073] The present application also provides a surface structure, which includes a first structure and a second structure; the first structure and the second structure are arranged on a substrate; the preparation process of the first structure includes: placing the substrate whose surface is covered with a metal film in a variable temperature environment; when the temperature of the variable temperature environment reaches a first temperature, maintaining the first temperature for a first time, cooling the substrate whose surface is covered with the metal film to a second temperature to form the first structure in the metal film; the preparation process of the second structure includes: when the size of the formed first structure reaches a target size, etching based on the first structure to form a second structure complementary to the first structure on the substrate.

[0074] In the above implementation process, a substrate with a metal film on its surface is placed in a variable temperature environment. When the ambient temperature reaches a first temperature, the temperature is maintained for a first period of time, and the metal film undergoes grain growth or phase change at high temperature to form a specific microstructure (such as a granular or columnar structure). The substrate is then cooled to a second temperature to form a first structure in the metal film. The first temperature mainly affects the degree of heat treatment of the metal film to form the first structure (such as a metal nano-island structure), and affects the surface tension of the metal under high temperature conditions. The second temperature mainly affects the time of heat treatment and affects the degree of forming of the first structure.

[0075] In the above implementation process, when the size of the first structure reaches the target size, etching is performed based on the first structure. The etching process forms a second structure on the substrate that is complementary to the first structure. The first structure, which serves as a metal mask, and the substrate covered by it are simultaneously etched using an etching gas. The areas covered by the metal mask are not etched, while the blank areas are etched, thereby forming a complementary second structure (such as nanocones and nanopillars formed on the substrate). Using the first structure as a mask, by controlling the etching time and conditions, the size of the second structure is ensured to be complementary to the first structure.

[0076] In one embodiment of the present application, transmittance tests were conducted on quartz substrate samples, samples with single-sided nanostructures on the substrate, and samples with double-sided nanostructures on the substrate. The results showed that the transmittance of the sample with double-sided nanostructures increased significantly over a wide spectral range (bandwidth up to 800nm or more), and the transmittance of the sample with single-sided structure also increased. The increase in transmittance is approximately proportional to the number of layers of the surface structure. The preparation of the double-sided nanostructure relies on coating and annealing on both sides separately, so that both sides have metal masks, and then etching both sides separately to achieve the preparation of the double-sided nanostructure. During the preparation of the double-sided structure, the sample is clamped by a fixture in the three steps of coating, annealing, and etching to protect the structure on the other side from being damaged.

[0077] See also Figures 5 to 8 , Figure 5 This is an electron microscope scan of metal nanoparticles on the surface of the substrate during the preparation process provided in the examples of this application. Figure 6 This is an electron microscope scanning image of the nano-columnar structure after dry etching on the substrate surface provided in the embodiment of the present application.

[0078] In one embodiment of the present application, the substrate is quartz, and the prepared surface structure has a diameter ranging from 20 to 200 nm, an aspect ratio of 3 to 5, and a filling ratio of 75%. Figure 5 The scanning electron microscope image shows a top view of the metal nano-island structure on the surface of the substrate after coating and annealing treatment, indicating that the metal nanoparticles on the surface of the substrate are evenly distributed during the preparation process. The white area is the metal island particles, the black area is the air area, and the particles are mainly metal nanoparticles of random sizes. Figure 6 The scanning electron microscope image shows a 45° observation image of the nanostructure on the surface of the etched substrate, which shows that the nanostructure is a metal nanocolumn structure that is densely and orderly arranged.

[0079] Figure 7 This is a diagram showing the anti-reflection effect of the surface nanostructure provided in the embodiment of the present application; Figure 8 This is a test chart of the surface hydrophobic effect and scratch resistance.

[0080] Figure 7 This is a diagram showing the anti-reflection effect of the surface nanostructure provided in the examples of this application. The prepared surface structure was tested for hydrophobicity and scratch resistance. The contact angle of water on an ordinary quartz substrate is only about 38°. However, after fluorination, the contact angle reached 156°, demonstrating super-hydrophobic properties (>150°). The surface retained good hydrophobicity even after direct scraping with a blade, demonstrating the high hardness and mechanical stability of the prepared surface structure, as well as its scratch resistance.

[0081] In summary, the preparation method realizes the formation of the target structure through a series of steps, specifically including five key links: metal film preparation, annealing, size adjustment, deposition and fluorination treatment. Throughout the implementation process, the parameters of the metal film preparation, annealing, size adjustment, deposition and fluorination treatment steps need to be strictly controlled to ensure that the formation of the first structure and the second structure meets expectations. The low power, inert gas protection and low pressure environment settings of magnetron sputtering coating further optimize the quality and performance of the metal film, providing a good foundation for subsequent annealing and deposition processes. In addition, by repeating the annealing process, the size of the first structure can be adjusted to ensure the accuracy and performance of the final structure. The selection and optimization of the dry etching process ensures the high precision and high quality of the second structure. The introduction of fluorination treatment further enhances the stability and durability of the pattern, giving the preparation method a wider application prospect in micro-nano processing, materials science and semiconductor manufacturing.

[0082] In the several embodiments provided herein, it should be understood that the disclosed methods may also be implemented in other ways. The embodiments described above are merely illustrative, and it should be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than that marked in the accompanying drawings. For example, two consecutive blocks may actually be executed substantially in parallel, or they may sometimes be executed in the opposite order, depending on the functions involved.

[0083] The foregoing is merely an embodiment of the present application and is not intended to limit the scope of protection of the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures.

[0084] The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.

[0085] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, the elements defined by the phrase "comprising..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements.

Claims

1. A method for preparing a surface structure, characterized in that: The preparation method includes: an annealing process and a deposition process; Wherein, the annealing process includes: Placing the substrate with the metal film on its surface in a variable temperature environment; When the temperature of the variable temperature environment reaches a first temperature, the first temperature is maintained for a first period of time, and then the substrate with the metal film covered on the surface is cooled to a second temperature to form a first structure in the metal film; Wherein, the deposition process includes: When the size of the formed first structure reaches a target size, etching is performed based on the first structure to form a second structure complementary to the first structure on the substrate.

2. The preparation method according to claim 1, characterized in that The preparation method further comprises: a metal film preparation process; The metal film preparation process includes: After cleaning the substrate with a plurality of cleaning solvents, the substrate is dried; When the substrate is completely dried, a metal film is plated on the substrate using a coating process; Wherein, the metal is one of gold, silver and platinum, and the thickness of the metal film is 3nm to 10nm; The coating process includes physical vapor deposition, chemical vapor deposition, electroplating, solution deposition and spraying.

3. The preparation method according to claim 2, characterized in that in, The coating process is magnetron sputtering coating; The power of the magnetron sputtering coating is maintained within a low power range, the protective gas is an inert gas, and the working gas pressure during the coating process is set within a low pressure range.

4. The preparation method according to claim 1, characterized in that When the temperature of the variable temperature environment reaches a first temperature, maintaining the first temperature for a first period of time, and then cooling the substrate having the metal film covered on the surface to a second temperature comprises: placing the substrate with the metal film on its surface covered in a high-temperature annealing furnace, maintaining a heating rate of 20°C / min, and heating to the first temperature; While maintaining the substrate in an environment of the first temperature for a first period of time, cooling the substrate to a second temperature and then removing the substrate; The first temperature ranges from 600 to 1000° C., and the second temperature is consistent with room temperature.

5. The preparation method according to claim 1, characterized in that The method further includes: if the size of the first structure does not meet the target size, repeating the annealing process until the size of the first structure meets the target size.

6. The preparation method according to claim 1, characterized in that The etching based on the first structure to form a second structure complementary to the first structure on the substrate includes: Using the first structure as a mask, a second structure is prepared on the substrate by a dry etching process; The dry etching process is one of reactive ion etching, ion beam etching and high-density plasma etching.

7. The preparation method according to claim 6, characterized in that in, In the dry etching process, the etching radio frequency power adopts low-power etching, the etching reaction gas is a fluorine-based gas, the ambient pressure is maintained at a low-pressure environment, and the etching is performed at a flow rate not higher than 20 sccm.

8. The preparation method according to claim 1, characterized in that The deposition process further comprises: performing a fluorination treatment while transferring the pattern formed by the first structure to the substrate; Wherein, the fluorination treatment is one of vapor deposition or immersion in a fluorine-containing solution.

9. The preparation method according to claim 8, characterized in that In the case where the pattern formed by the first structure is transferred to the substrate, the substrate is immersed in a fluorine-containing solution; Wherein, the fluorine-containing solution is a mixed solution of fluorosilane solution and alcohol.

10. A surface structure, characterized in that The surface structure includes a first structure and a second structure; The first structure and the second structure are disposed on a substrate; The preparation process of the first structure includes: placing a substrate having a surface covered with a metal film in a variable temperature environment; when the temperature of the variable temperature environment reaches a first temperature, maintaining the first temperature for a first period of time, and then cooling the substrate having the surface covered with the metal film to a second temperature to form the first structure in the metal film; The preparation process of the second structure includes: when the size of the formed first structure reaches a target size, etching based on the first structure to form a second structure complementary to the first structure on the substrate.

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