Flattened structure

Abstract

A method for producing a planarized structure comprising a metal-containing or semimetallic coating layer between a first film and a second film of carbon nanostructures. [Solution] The method includes the steps of: providing a first film of carbon nanostructures; forming a polymer-based material on the first film of carbon nanostructures by a solution-based deposition technique to form a planarization layer on the first film of carbon nanostructures; forming a metal-containing or metalloid-containing material on the planarization layer by a vapor deposition technique to form a planarized metal-containing or metalloid-containing coating layer on the planarization layer; providing a second film of carbon nanostructures on the planarized metal-containing or metalloid-containing coating layer to form a prestructure; subjecting the formed prestructure to a densification treatment; and producing a planarized structure by removing the planarization layer from the prestructure by a dissolution technique.

Description

Technical Field

[0001] The present disclosure relates to a method for producing a planarized structure composed of a metal-containing or metalloid-containing coating layer between a first film and a second film of carbon nanostructures. The present disclosure further relates to the use of the planarized structure.

Background Art

[0002] Extreme ultraviolet lithography (EUV or EUVL) is an optical lithography technique that uses a specific range of extreme ultraviolet wavelengths. EUV pellicle films are used to protect photomasks from defects, improve accuracy, shorten processing, and increase production efficiency on wafers. However, defects in printing still remain a major constraint on the popularization of EUV lithography. Furthermore, an optical filter is a component designed to selectively transmit or block light of a specific wavelength. These filters play a role in applications such as spectroscopy, communication, biomedical imaging, and photography. The materials and coating techniques used determine their performance, including spectral range, durability, and heat resistance. Despite their advantages, the performance of optical filters can be limited by challenges such as durability under high-power laser applications, thermal degradation, and manufacturing tolerances. Problems such as surface defects, coating mismatches, or environmental factors including humidity can lead to scattering or absorption losses, reducing filter efficiency and service life. Therefore, there is a need for sophisticated particulate filters such as EUV pellicles or optical filters.

Summary of the Invention

[0003] Disclosed is a method for producing a planarized structure composed of a metal-containing or metalloid-containing coating layer between a first film and a second film of carbon nanostructures. The method comprises: • providing a first film of carbon nanostructures, and The steps include: forming a polymer-based material on the first film of the carbon nanostructure by a solution-based deposition technique to form a planarization layer on the first film of the carbon nanostructure; The steps include forming a metal-containing or metalloid-containing material on the planarized layer by a vapor deposition technique to form a planarized metal-containing or metalloid-containing coating layer on the planarized layer, The steps include: providing a second film of carbon nanostructures on the planarized metal-containing or semimetallic coating layer to form a prestructure; The steps include: applying a densification treatment to the formed prestructure, The steps include: • Removing the planarization layer from the prestructure by a dissolution technique to produce the planarization structure; Includes.

[0004] Furthermore, the use of planarization structures obtained by the methods disclosed herein as optical filters, optical mirrors, debris filters, pellicles, membrane filters, electron blocking windows, X-ray windows, X-ray optical filters, and X-ray optical filter mirrors, or any combination of at least two thereof, is disclosed. [Brief explanation of the drawing]

[0005] The accompanying drawings are included to provide a further understanding of the embodiments, constitute part of this specification, illustrate the embodiments, and help illustrate the principles of the invention together with the description.

[0006] [Figure 1] One embodiment for manufacturing a flattened structure is shown. [Figure 2] The results of Example 2 are shown. [Modes for carrying out the invention]

[0007] This disclosure relates to a method for producing a planarized structure comprising a metal-containing or semimetallic coating layer between a first film and a second film of carbon nanostructures, wherein the method is: • A step of providing a first film of carbon nanostructures, The steps include: forming a polymer-based material on the first film of the carbon nanostructure by a solution-based deposition technique to form a planarization layer on the first film of the carbon nanostructure; The steps include forming a metal-containing or metalloid-containing material on the planarized layer by a vapor deposition technique to form a planarized metal-containing or metalloid-containing coating layer on the planarized layer, The steps include: providing a second film of carbon nanostructures on the planarized metal-containing or semimetallic coating layer to form a prestructure; The steps include: applying a densification treatment to the formed prestructure, The steps include: • Removing the planarization layer from the prestructure by a dissolution technique to produce the planarization structure; Includes.

[0008] This disclosure further relates to the use of planarization structures obtained by the methods disclosed herein as optical filters, optical mirrors, debris filters, pellicles, membrane filters, electron blocking windows, X-ray windows, X-ray optical filters, and X-ray optical filter mirrors, or any combination of at least two thereof.

[0009] In one embodiment, the planarized structure is used as an extreme ultraviolet lithographic pellicle.

[0010] In one embodiment, the planarized structure consists of a metal-containing or semimetallic coating layer between a first film and a second film of carbon nanostructures.

[0011] In one embodiment, the first and second films of the carbon nanostructure are either self-supporting films of the carbon nanostructure or mesh-supported films of the carbon nanostructure.

[0012] In this specification, the term "mesh" may refer to an entangled structure. A mesh may be considered, for example, a support made of entangled strands of metal.

[0013] Carbon nanostructures are used to form the first and second films. The term "nanostructure" should be understood herein, unless otherwise specified, as a structure having one or more characteristic dimensions on a nanometer scale, typically in the range of 1 to 100 nm. The dimensions of the nanostructure may differ significantly in two perpendicular directions by orders of magnitude. For example, a nanostructure may have a length 10, 100, 1000, or even 100,000 times greater than its thickness or width. In a film of carbon nanostructures, when carbon nanotubes are collected on a filter, many of the carbon nanostructures may be interconnected to form a network of interconnected molecules. The carbon nanostructures may also maintain a vertically oriented, aligned or semi-aligned configuration when carbon nanotubes are harvested from a carbon nanotube forest. A carbon nanotube forest is a high-density, vertically aligned array of carbon nanotubes. These structures may be grown on a substrate using techniques such as chemical vapor deposition. When processed into a film, these structures may exhibit partial interconnections through van der Waals forces or physical entanglement, forming a network while retaining some of the alignment properties of the original forest. Considered on a macroscale, such a network forms a solid monolithic material, whose individual molecular structures are either unoriented or unoriented, i.e., substantially randomly oriented or oriented. Various types of carbon nanostructure networks can be fabricated in the form of thin, transparent layers.

[0014] In one embodiment, the carbon nanostructure is a carbon nanotube (CNT), a carbon nanobud (CNB), a carbon nanoribbon, a carbon nanofiber, or any combination or mixture thereof. In one embodiment, the carbon nanostructure is a carbon nanotube, a carbon nanobud, or any combination or mixture thereof. A carbon nanobud, or possibly a carbon nanobud molecule, has a fullerene or fullerene-like molecule covalently bonded to the side of a tubular carbon molecule. Carbon nanotubes and carbon nanobuds themselves have the additional utility of being highly transparent at X-ray and visible light wavelengths. Furthermore, they have strong mechanical properties and high chemical inertness.

[0015] In this art, various procedures exist that can be used to form first and second films of carbon nanostructures. Different methods may be used to synthesize carbon nanostructures and / or deposit them to form films. For example, in the case of carbon nanotubes or carbon nanobud molecules, deposition may be carried out using well-known methods such as filtration from the gas phase or liquid, extraction from solution, deposition in a force field, harvesting from a carbon nanotube forest, or deposition from solution using spray coating or spin drying. Carbon nanobud molecules can be synthesized, for example, using the method disclosed in International Publication No. 2007 / 057501, and deposited on a substrate, for example, directly from an aerosol stream, with the help of electrophoresis or thermophoresis, for example, or by the method described by Nasibulin et al., "Multifunctional Free-Standing Single-Walled Carbon Nanotube Films" (ACS NANO, vol. 5, no. 4, 3214-3221, 2011). The functionalization of carbon nanostructures may be considered as the generation of functional groups on the surface of the carbon nanostructures. The functionalization of carbon nanostructures may be carried out by either physicoadsorption or covalent bonding. Functionalization of carbon nanostructures has additional utility, such as making them more reactive, increasing their solubility, or enabling various chemical modifications such as ion adsorption, metal deposition, or grafting reactions.

[0016] The first and / or second films of carbon nanostructures may be formed, for example, by synthesizing the carbon nanostructures in a gas phase in which the carbon nanostructures are collected or deposited. The carbon nanostructures may be collected or deposited to form a film that does not have a particular orientation, or they may be aligned in a particular direction.

[0017] The first and / or second films of the carbon nanostructure are 0.1 to 1000 cm². 2 , or 1-500cm 2 , or 5-350cm2 , or 10-200cm 2 , or 50-150cm 2 It may have the following area size.

[0018] The thickness of the first and / or second film of the carbon nanostructure may be 1-8000 nm, or 5-7500 nm, or 15-7000 nm, or 20-5000 nm, or 50-2500 nm, or 100-1000 nm, or 200-600 nm. In one embodiment, the thicknesses of the first and second films of the carbon nanostructure are 1-600 nm, or 15-500 nm, or 20-400 nm, or 50-300 nm, or 100-200 nm, or 75-100 nm. In one embodiment, the thicknesses of the first and second films of the carbon nanostructure are 100-8000 nm, or 200-7000 nm, or 300-5000 nm, or 400-2500 nm, or 500-1000 nm. The thicknesses of the first and second films of the carbon nanostructure may be measured using a contact profilometer such as an atomic force microscope (AFM), an optical profilometer, ellipsometry, or a cross-sectional electron microscope. Forming the first and second films of the carbon nanostructure has the additional benefit of allowing the formation of thin films. However, the first and second films of the carbon nanostructure should not be too thin, because if they are too thin, it will affect their ability to support themselves when forming self-supporting films. In contrast, if the films are supported by a mesh, the thicknesses of the first and second films can be varied more freely.

[0019] The first and second carbon nanostructure films may be either free-standing films of carbon nanostructures or mesh-supported films of carbon nanostructures. The free-standing film may be one that can exist as the free-standing film itself without requiring a supporting substrate. The free-standing film of carbon nanostructures may be self-supporting, which means that the film has sufficient mechanical integrity and strength to maintain its structure independently. The free-standing film may typically be formed directly as an independent entity, or a film grown on a substrate may be manufactured so as to be free-standing after removal of the substrate. The property that defines any free-standing film may be the ability to maintain its structure without a supporting substrate. Regardless of whether the free-standing film is formed on a substrate, the free-standing film can be regarded as a free-standing film after any processing step, particularly when, as described above, the free-standing film can exist and function independently. Since the free-standing film can maintain its structure without direct support, it does not need to be directly supported over its entire area. It provides inherent structural support on its own to maintain its structure, for example, its shape. This can be observed under gravity in the absence of a supporting force for the free-standing film. Therefore, the free-standing film described herein can also be understood as a self-supporting film.

[0020] The first and / or second film of carbon nanostructures may be attached to a support. The support may be any type of support suitable for bonding with a free-standing film of carbon nanostructures. The support may be formed of glass, metal, plastic, or any combination thereof. The support may have various forms. The support may be in the form of a frame. In one embodiment, the support is in the form of a frame, and the film or carbon nanostructure is attached to the frame. The frame may support the free-standing film of carbon nanostructure at an outer edge thereof such that an unsupported independent region of the carbon nanostructure film is formed. The support position may be located anywhere on the structure as long as it can provide sufficient support for the carbon nanostructure film. For example, the support position may be on a side surface of the free-standing film of carbon nanostructure, in a region near a corner, or adjacent to each other along the side surface. Larger regions including multiple support points are also intended to be covered by this aspect, for example, when the frame has an unbroken circular shape with a free-standing region located within the circle. The frame may also have any other elongated unbroken shape. In one embodiment, the frame is shaped as a circle, a square, a triangle, a rectangle, an ellipse, or a polygon.

[0021] A polymer-based material is formed on the film of carbon nanostructures to form a planarization layer. As used herein, the term "polymer-based material" may be interpreted to refer to a material having a polymer content of 50 to 100% by weight. Examples of the polymer-based material used to form the planarization layer include organic polymers such as parylene and polyamide; naphthalene-containing polymers; oxygen-containing polymers such as poly(methyl methacrylate) (PMMA); hydrocarbon-based polymers composed of carbon and hydrogen such as polystyrene; oligomers such as short-chain polystyrene and oligoethylene glycol; solvent-processable fluoropolymers such as polyvinylidene fluoride (PVDF); and polyolefins such as polypropylene, polyethylene, and polymethylpentene.

[0022] Polymer-based materials can be formed on a first film of carbon nanostructures by solvent-based deposition techniques. Solution-based deposition techniques may be any general-purpose method, in which the solution of the coating material is applied to the film by brushing, spraying, dipping, diffusion, or dropwise application.

[0023] In one embodiment, the solution-based deposition technique is selected from spin casting, alternating lamination, spray coating, electrophoretic deposition, Langmuir-Bludget method, curtain coating, slot die coating, or dip coating. These techniques are particularly advantageous for coating delicate self-supporting CNT films because they typically involve lower mechanical stress compared to vacuum-based methods.

[0024] Using solution-based deposition techniques to form planarization layers has the added benefit of allowing precise control over the thickness of the resulting layer, enabling layer thicknesses up to tens of nanometers. Solution-based deposition techniques also have the added benefit of efficiently filling any gaps present between carbon nanostructures in the film without the need to form thick layers. In one embodiment, the solvent-based deposition technique is dip coating. Dip coating for forming planarization layers is beneficial for optical applications because it produces a smooth, uniform, and defect-free coating. Furthermore, dip coating is a cost-effective technique due to its simple setup and minimal equipment requirements.

[0025] In one embodiment, the method includes the step of forming a planarization layer having a thickness of 1 to 200 nm, 5 to 180 nm, 10 to 150 nm, 20 to 100 nm, 30 to 80 nm, or 40 to 60 nm. The thickness of the planarization layer may be measured, for example, by using the cross-section of an electron microscope or X-ray reflectance.

[0026] The planarization layer has the additional benefit of providing a smooth and uniform surface before forming a metal-containing or metalloid-containing coating layer on top of it. Surface irregularities at this stage will be transferred to the metal-containing or metalloid-containing coating layer in a way that negatively impacts the final use of the structure.

[0027] After the planarization layer is formed, a metal-containing or metalloid-containing material is formed on it by a vapor deposition technique to form a planarized metal-containing or metalloid-containing coating layer. As used herein, the term “metal-containing material” may be interpreted as referring to a material containing a metal element or a metal-containing compound. In one embodiment, the metal-containing material has a metal content of 50–100% by weight. In one embodiment, the metalloid-containing material has a metalloid content of 50–100% by weight. Thus, the planarized metal-containing or metalloid-containing coating layer may contain a total of 50–100% by weight of metal or metalloid. In one embodiment, the vapor deposition technique is selected from sputtering deposition, electron beam physical deposition, thermal deposition, cathode arc deposition, pulsed laser deposition, or ion beam assisted deposition. Sputtering deposition uses plasma to eject material from a target and then deposit it on the planarization layer. Electron beam physical deposition uses a high-speed electron beam to evaporate the coating material and then condense the coating material on the planarization layer. In thermal deposition, the deposition material is heated to a high vapor pressure using electrical resistance, allowing it to be deposited on a planar layer. In cathode arc deposition, a high-power electric arc is used to vaporize the target material, which is then deposited on a planar layer. In pulsed laser deposition, a high-power laser is used to ablate the metal from the target, generating vapor which is then deposited on a planar layer. Ion beam-assisted deposition combines physical vapor deposition with ion irradiation shock to improve film properties.

[0028] Using vapor deposition techniques to form metal-containing or metalloid-containing coating layers has the additional benefit of being able to form thin coating layers with a smooth and uniform surface. Vapor deposition techniques also have the additional benefit of being able to precisely control the coating thickness on a nanometer scale, which is highly beneficial for EUV pellicles.

[0029] In one embodiment, the metal-containing or metalloid-containing coating layer has a thickness of 1-1000 nm, 1-800 nm, 1-500 nm, 1-300 nm, 3-100 nm, 5-50 nm, 7-30 nm, 9-20 nm, or 10-15 nm. The thickness of the metal-containing or metalloid-containing coating layer may be measured, for example, using transmission electron microscopy (TEM), scanning electron microscopy (SEM), or any other relevant technique.

[0030] In one embodiment, the metal-containing material is a material based on aluminum, zirconium, tungsten, niobium, titanium, yttrium, molybdenum, hafnium, vanadium, chromium, tantalum, scandium, gold, palladium, or lanthanum.

[0031] In one embodiment, the metalloid-containing material is a boron or silicon-based material.

[0032] The metal-containing or metalloid-containing coating layer may contain, or consist of, aluminum, zirconium, tungsten, niobium, titanium, yttrium, hafnium, vanadium, chromium, tantalum, scandium, gold, palladium, lanthanum, iron, nickel, cobalt, manganese, boron, or molybdenum, or silicon, or any carbides, oxides, nitrides, sulfides, or borides thereof, or any combination or mixture thereof. After the planarized metal-containing or metalloid-containing coating layer is formed, a second film of carbon nanostructures is formed on it.

[0033] After forming the prestructure, it is subjected to a densification process. In one embodiment, the densification process is gas-phase densification, thermal annealing, electrostatic compression, or liquid immersion densification. The densification process has the additional benefit of improving the mechanical strength, electrical conductivity, optical properties, and overall uniformity of the carbon nanostructure film. In one embodiment, gas-phase densification is chemical gas-phase immersion. In one embodiment, liquid immersion densification is solvent-assisted densification. Liquid immersion densification has the additional benefit of eliminating the need for vacuum conditions and mechanical pressure, thereby providing a milder and gentler process.

[0034] In one embodiment, the vapor densification process is carried out using a vapor-phase solvent at a temperature of 55-250°C, 55-150°C, 55-100°C, 55-75°C, or 60-70°C for 15-120 seconds, 20-90 seconds, or 30-60 seconds. The vapor-phase solvent may be isopropyl alcohol. The vapor densification process may also be carried out using a vapor-phase solvent, i.e., a vaporized medium. The formed prestructure may be placed in a chamber into which solvent vapor is introduced. This solvent vapor can then condense on the prestructure, forming a thin liquid solvent film. The drying effect and surface tension of the solvent film can then cause the structures of the prestructure to attract each other, forming a denser and more mechanically robust structure. Densification of the prestructure has the additional utility of bonding or joining the carbon nanostructure film to a metal-containing or semimetallic coating layer so that they adhere to each other. The adhesion is maintained even under harsh conditions.

[0035] After densification, the planarization layer is removed from the prestructure by a dissolution technique to produce the planarization structure. The planarization layer functions as a sacrificial layer because it is removed to produce the planarization structure. In one embodiment, the dissolution technique is selected from wet chemical etching, dry etching, thermal decomposition, supercritical CO2 removal, electrochemical dissolution, solvent-based swelling and dissolution, or gas-phase etching. The dissolution technique has the additional utility of being able to remove the planarization layer from the prestructure without attacking the metal-containing or metalloid-containing coating layer or the carbon nanostructure film. Wet chemical etching uses a liquid solvent or etchant to chemically react with the sacrificial layer and selectively dissolve it. Dry etching uses a reactive gas (plasma) to etch the sacrificial layer without using a liquid solvent. Thermal decomposition uses high temperature to decompose the sacrificial layer. Supercritical CO2 removal uses supercritical carbon dioxide (CO2) as a solvent to remove the sacrificial layer in a controlled process. Electrochemical dissolution uses a voltage in a suitable electrolyte to etch the layer. Solvent-based swelling and dissolution use a solvent to swell and dissolve the material. Gas-phase etching uses reactive gas-phase chemicals to selectively remove the sacrificial layer.

[0036] As the exposed surface area increases, oxidation progresses more easily, which can lead to a significant decrease in UV transmittance. Therefore, planar structures with a smaller exposed surface area have the added benefit of minimizing oxidation and achieving higher UV transmittance. A smaller exposed surface area also means fewer pores, voids, or rough areas where dust or foreign matter can accumulate. This not only reduces the possibility of contamination but also helps maintain the cleanliness and performance of the optical film over time. This is especially important for optical films used in high-precision applications, where even small amounts of contamination can degrade performance. Therefore, smoother, less exposed surfaces make it more difficult for contaminants to interact with the material, resulting in improved long-term stability and durability. [Examples]

[0037] The embodiments described here will be explained in detail, but examples are shown in the attached drawings.

[0038] The following description discloses several embodiments in such detail that a person skilled in the art could utilize the method based on this disclosure. Not all steps of the embodiments are discussed in detail, as some steps may be obvious to a person skilled in the art based on this specification.

[0039] Figure 1 shows one embodiment for manufacturing the planarized structure disclosed herein.

[0040] First, a first film of carbon nanostructures is provided. The first film of carbon nanostructures may be formed, for example, by a gas-phase process, where carbon nanostructures such as carbon nanotubes (denoted as CNTs in Figure 1) are synthesized in the gas phase and then deposited or collected on a substrate such as a porous filter. The formed film of carbon nanostructures can be peeled from the substrate and transferred to a support such as a frame.

[0041] Next, a polymer-based material (labeled PMMA in Figure 1) is formed on a first film of carbon nanostructures (CNTs) using a solution-based deposition technique, and a planarization layer is formed on the first film of carbon nanostructures.

[0042] Next, a metal-containing or metalloid-containing material (indicated as "metal" in Figure 1) is formed on a planarized layer (PMMA) by vapor deposition techniques, and a planarized metal-containing or metalloid-containing coating layer is formed on the planarized layer.

[0043] Next, a second film of carbon nanostructures (denoted as CNTs) is provided on a planar metal-containing or metalloid-containing coating layer (metal) to form a prestructure.

[0044] Following these steps, the formed prestructure is subjected to a densification treatment, and then the planarization layer is removed from the prestructure by a dissolution technique to produce a planarized structure. Thus, the planarized structure is formed from a metal-containing coating layer or a metalloid-containing coating layer between the first and second films of the carbon nanostructure.

[0045] (Example 1 - Manufacturing of a flattened structure) In this example, a planarized structure was fabricated. The materials used are shown in Table 1. [Table 1]

[0046] First, carbon nanotubes were synthesized in an aerosol laminar flow (floating catalyst) reactor using carbon monoxide as the carbon source and ferrocene as the catalyst precursor. The formed carbon nanotubes were deposited from the gas phase onto a porous collection filter at a total gas flow rate of 60 l / min (maximum gas velocity of 0.13 m / s) to form a carbon nanotube film on the porous collection filter. The gas temperature was approximately 60°C. The thickness of the first carbon nanotube film formed was 50 nm, which corresponds to 81%T at a wavelength of 550 nm.

[0047] Next, the first film of carbon nanotubes was transferred from the porous collection filter to a rectangular plastic frame larger than the final circular frame. This was then transferred to the final circular frame to form a self-supporting film of carbon nanotubes attached to the frame. Thus, the frame had a circular shape with an opening in the center.

[0048] Subsequently, a polymer-based material was deposited onto the first film of carbon nanotubes by dip coating, with a dip coating immersion and withdrawal rate of 25 mm / min. After coating, the film was dried in a ventilated oven at 100°C for 15 minutes. In this example, PMMA was used as the polymer-based material.

[0049] Next, a metal-containing coating layer of Au / Pd alloy was formed on the planarized layer using physical vapor deposition (VPD) technology, in this case sputtering deposition using argon plasma (base pressure 1E-5 mbar, operating pressure 1E-2 mbar, deposition rate approximately 10 nm / min, unheated sample, sputtering target was pre-washed for 1 minute before deposition to remove native oxides). The thickness of this metal-containing coating layer was 50 nm.

[0050] Next, a film of carbon nanotubes manufactured as described above was formed on the metal-containing coating layer.

[0051] Next, the formed prestructure was placed in a chamber, and isopropanol vapor was introduced into it at a temperature of 66°C for 60 seconds to perform a vapor-phase densification treatment on the prestructure.

[0052] After vapor-phase densification, the planarization layer was removed from the prestructure using a dissolution technique. Next, the film was immersed in acetone solvent at 50°C for 1 hour, using the same immersion and withdrawal parameters as those used for PMMA deposition.

[0053] (Example 2 - Manufacturing of a flattened structure) In this example, a planarized structure was fabricated and tested. The materials used are shown in Table 2. [Table 2]

[0054] First, carbon nanotubes were synthesized in an aerosol laminar flow (floating catalyst) reactor using carbon monoxide as the carbon source and ferrocene as the catalyst precursor. The formed carbon nanotubes were deposited from the gas phase onto a porous collection filter at a total gas flow rate of 60 l / min (maximum gas velocity of 0.13 m / s) to form a carbon nanotube film on the porous collection filter. The gas temperature was approximately 60°C. The thickness of the first carbon nanotube film formed was 50 nm, which corresponds to 81%T at a wavelength of 550 nm.

[0055] Next, the first film of carbon nanotubes was transferred from the porous collection filter to a rectangular plastic frame larger than the final circular frame. This was then transferred to the final circular frame to form a self-supporting film of carbon nanotubes attached to the frame. Thus, the frame had a circular shape with an opening in the center.

[0056] Subsequently, a polymer-based material was deposited onto the first film of carbon nanotubes by dip coating, with a dip coating immersion and withdrawal rate of 25 mm / min. After coating, the film was dried in a ventilated oven at 100°C for 15 minutes. In this example, PMMA was used as the polymer-based material.

[0057] Next, a Zr metal-containing coating layer was formed on the planarized layer using physical vapor deposition (VPD), in this case, sputtering deposition using argon plasma (base pressure 1E-5 mbar, operating pressure 5.3E-3 mbar, deposition rate approximately 1.83 Å / min (11 nm / min), unheated sample, sputtering target pre-washed for 1 minute before deposition to remove native oxides). The thickness of this metal-containing coating layer was 50 nm.

[0058] Next, a film of carbon nanotubes manufactured as described above was formed on the metal-containing coating layer.

[0059] Next, the formed prestructure was placed in a chamber, and isopropanol vapor was introduced into it at a temperature of 66°C for 60 seconds to perform a vapor-phase densification treatment on the prestructure.

[0060] After vapor-phase densification, the planarization layer was removed from the prestructure using a dissolution technique. Next, the film was immersed in acetone solvent at 50°C for 1 hour, using the same immersion and withdrawal parameters as those used for PMMA deposition.

[0061] EUV measurements were performed on the formed planarized structure using a particle accelerator (synchrotron). The results are shown in Figure 2.

[0062] (Example 3 - Testing of flattened structure) In this example, a planarized structure manufactured according to the description in Example 2 was tested and compared with a sample in which a metal-containing coating layer was directly formed on a carbon nanotube film without using a planarized layer.

[0063] EUV measurements were performed on the formed samples using a particle accelerator (synchrotron). The results are shown in Figure 2.

[0064] These results show that when a planarized structure was fabricated, that is, when a planarized layer of polymer-based material was used and a Zr-containing coating layer was formed on top of it, the visible transmittance was approximately 7.5%, whereas when the same material was formed directly on a carbon nanostructure film without using a planarized layer of polymer-based material, the visible transmittance was approximately 14.8%.

[0065] This difference in visible transmittance can be concluded to be due to pinholes in the porous carbon nanotube film, in contrast to the case where a Zr-containing coating layer is formed on the planarization layer, resulting in a continuous surface and ideally no pinholes.

[0066] Furthermore, it was concluded that directly forming a Zr-containing coating layer on a porous carbon nanotube film leads to oxidation due to its disordered morphology, which in turn increases chemical reactivity.

[0067] As technology advances, it is obvious to those skilled in the art that basic ideas can be implemented in a variety of ways. Therefore, the embodiments are not limited to the examples described above and may be modified within the scope of the claims.

[0068] The embodiments described above may be used in any combination with each other. Some of the embodiments may be combined together to form further embodiments. Any method, structure, or use disclosed herein may include at least one of the embodiments described herein. It will be understood that the benefits and advantages described above may relate to one embodiment or to several embodiments. Embodiments are not limited to solving any or all of the problems described or having any or all of the benefits and advantages described. It will also be understood that a reference to "one" item may refer to one or more of these items. The term "comprising" is used herein to mean including any subsequent feature or action, and not to exclude the presence of one or more additional features or actions.

Claims

1. A method for producing a planarized structure comprising a metal-containing or semimetallic coating layer between a first film and a second film of carbon nanostructures, - A step of providing a first film of carbon nanostructures, - A step of forming a planarization layer on the first film of carbon nanostructures by forming a polymer-based material on the first film of carbon nanostructures using a solution-based deposition technique, - A step of forming a metal-containing or metalloid-containing material on the planarized layer by a vapor deposition technique to form a planarized metal-containing or metalloid-containing coating layer on the planarized layer, - A step of providing a second film of carbon nanostructures on the planarized metal-containing or semimetallic coating layer to form a prestructure, - A step of applying a densification treatment to the formed prestructure, - A step of manufacturing the planarized structure by removing the planarized layer from the prestructure using a dissolution technique, Methods that include...

2. The method according to claim 1, wherein the first film and the second film of the carbon nanostructure are a self-supporting film of the carbon nanostructure or a mesh-supported film of the carbon nanostructure.

3. The method according to claim 1 or 2, wherein the polymer-based material is polymethyl methacrylate.

4. The method according to claim 1 or 2, wherein the metal-containing material is a material based on aluminum, zirconium, tungsten, niobium, titanium, yttrium, molybdenum, hafnium, vanadium, chromium, tantalum, scandium, gold, palladium, lanthanum, iron, nickel, cobalt, or manganese.

5. The method according to claim 1 or 2, wherein the semimetallic material is a silicon or boron-based material.

6. The method according to claim 1 or 2, comprising the step of forming a metal-containing or semimetallic coating layer having a thickness of 1 to 1000 nm, 1 to 800 nm, 1 to 500 nm, 1 to 300 nm, 3 to 100 nm, 5 to 50 nm, 7 to 30 nm, 9 to 20 nm, or 10 to 15 nm.

7. The method according to claim 1 or 2, wherein the solution-based deposition technique is selected from spin casting, alternating deposition, spray coating, electrophoretic deposition, Langmuir-Bludget method, curtain coating, slot die coating, or dip coating.

8. The method according to claim 1 or 2, wherein the vapor deposition technique is selected from sputtering deposition, electron beam physical deposition, thermal deposition, cathode arc deposition, pulsed laser deposition, or ion beam assisted deposition.

9. The method according to claim 1 or 2, wherein the densification treatment is gas-phase densification, thermal annealing, electrostatic compression, or liquid immersion densification.

10. The aforementioned dissolution techniques include wet chemical etching, dry etching, thermal decomposition, and supercritical CO2. ２ The method according to claim 1 or 2, selected from removal, electrochemical dissolution, solvent-based swelling and dissolution, or gas-phase etching.

11. Use of a planarization structure obtained by the method of claim 1 or 2 as an optical filter, optical mirror, debris filter, pellicle, membrane filter, electron blocking window, X-ray window, X-ray optical filter, and X-ray optical filter mirror, or any combination of at least two thereof.

12. The use according to claim 11, wherein the planarized structure is used as an extreme ultraviolet lithographic pellicle.

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