Manufacturing and equipment for nanofiber pellicle film

Abstract

Apparatus and method for producing a nanofiber pellicle film. A suspension of nanofibers is passed through a filter to produce a thin, preferably very thin, nanofiber pellicle film. The film is suspended from the filter and attached to a recovery frame that can be easily handled. The film may be dried and stored for further processing.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Provisional Application No. 63 / 454,429, filed on March 24, 2023, under 35 U.S.C. § 119(e), the entire content of which is incorporated herein by reference.

[0002] This disclosure generally relates to nanofiber pellicle films, and more particularly, to methods, apparatuses, and systems for the manufacture of nanofiber pellicle films.

Background Art

[0003] Nanofibers and nanotubes are known to have different mechanical, optical, and electronic properties. Nanotubes, including carbon nanotubes and boron nitride nanotubes, can be formed into various materials including nanotube fibers, nanotube threads, nanotube forests, and nanotube sheets or films. These materials can provide properties useful for various applications, but can be difficult to manufacture in large quantities.

Summary of the Invention

[0004] In a first embodiment, Example 1, a method of preparing a nanofiber film includes filtering an aggregate of nanofibers or nanotubes onto a filter, wherein the filter is disposed at the bottom of a reservoir in a first planar orientation, preferably horizontally, such that a layer of nanofibers or nanotubes (hereinafter also referred to as a nanofiber film) is formed; tilting the filter to a second planar orientation, wherein the second planar orientation has an inclination angle of at least 3 degrees from the first planar orientation; and immersing the filter with the layer of nanofiber film thereon into a fluid from the lowest point of the filter to separate the layer of nanofibers from the filter.

[0005] Example 2 includes the subject matter of Example 1, wherein nanofibers are filtered from the nanofiber suspension and the nanofiber suspension contains a fluid.

[0006] Example 3 is the subject of Example 2, wherein the fluid is selected from water, an aprotic polar solvent, isopropyl alcohol (IPA), or a combination thereof.

[0007] Example 4 includes the subject matter of Example 1, wherein the nanofibers are selected from at least one of carbon nanotubes, boron nitride nanotubes, carbon nanofibers, various nanofibers, or combinations thereof.

[0008] Example 5 includes the subject of Example 2, wherein the nanofiber suspension contains at least one nanoparticle.

[0009] Example 6 incorporates the subject matter of any of the prior examples, wherein nanofibers are randomly oriented on a filter and form an interconnected network.

[0010] Example 7 includes the subject matter of any of the prior examples and further includes suspending a layer of nanofibers away from the filter.

[0011] Example 8 includes the subject of Example 1, wherein the fluid surface is steadily rising and the fluid surface is applied to separate the nanofiber layer from the filter.

[0012] Example 9 incorporates the subject matter of Example 8, wherein a steadily rising fluid surface eventually submerges the upper end of the nanofiber layer, completely separating the nanofiber layer from the filter.

[0013] Example 10 includes the subject of Example 1, wherein a filter with a layer of nanofibers on top is immersed in a fluid at an angle of at least 3 degrees from the horizontal to separate the layer of nanofibers from the filter.

[0014] Example 11 includes the subject matter of any of the prior embodiments, wherein tilting the filter to a second planar orientation includes tilting the bottom of the reservoir together with the filter.

[0015] Example 12 includes the subject matter of Example 11, wherein at least one drain at the bottom of the reservoir allows communication between the inside and outside of the reservoir.

[0016] Example 13 includes the subject of Example 11, wherein the bottom of the reservoir has a plurality of openings forming a certain shape, the openings being selected from, but not limited to, a round shape, square, rectangular, polygonal, open or closed ring, honeycomb, or any combination thereof, and the shape depending on the layer of nanofibers is selected from any of the above shapes. The bottom of the reservoir may have any shape including an aggregate of the various individual solid geometric shapes described above, with a hollow periphery and a lower support structure. Preferred shapes may be rectangles having lengths and widths of 100 mm × 120 mm, 110 mm × 144 mm, 125 mm × 160 mm, 220 mm × 140 mm, or 110 mm × 280 mm or more. Another preferred shape may be a circle having a diameter greater than 14 cm (about 6 inches), 20 cm (about 8 inches), 30 cm (about 12 inches), or 38 cm (about 15 inches).

[0017] Example 14 includes the subject matter of any of the prior embodiments and further includes lifting a layer of nanofibers from the surface of a fluid.

[0018] Example 15 includes a subject from any of the prior embodiments, wherein the fluid reservoir base has a shape corresponding to the shape of the filter, or a shape different from the shape of the filter but large enough to accommodate the shape of the filter.

[0019] Example 16 includes the subject matter of Example 14 and further includes drying the nanotube layer.

[0020] Example 17 includes the subject matter of Example 16 where the drying method includes, but is not limited to, air drying, vacuum drying, and heat radiation drying.

[0021] Example 18 includes the subject matter of any of the preceding examples where at least a portion or the entire layer of nanofibers is floated on the surface of the fluid after being removed from the filter.

[0022] Example 19 is a device including a structural frame having a base, a liquid reservoir pivotally attached on the base, the liquid reservoir defining a drain, at least one opening at the bottom of the reservoir communicating with the drain, at least two fluid supply lines, and a film recovery mechanism.

[0023] Example 20 includes the subject matter of Example 19 where the first fluid supply line among the at least two fluid supply lines communicates with the supply part of the nanofiber suspension, and the second fluid supply line among the at least two fluid supply lines communicates with the fluid supply part.

[0024] Example 21 includes the subject matter of Example 20 where the fluid supply part contains water.

[0025] Example 22 includes the subject matter of Example 19 where at least one opening is a plurality of holes arranged in a certain shape, and each of the plurality of holes communicates with the reservoir and the drain.

[0026] Example 23 includes the subject matter of Example 22 where the shape includes, but is not limited to, a square, a rectangle, any polygon, a circular disk, any irregular shape, an array, or an array of any of the above-mentioned shapes.

[0027] Example 24 includes the subject matter of Example 19 where at least one opening includes a plurality of small geometric shapes surrounded by voids, and the geometric shapes have a lower support structure.

[0028] Example 25 includes the subject matter of Example 19 where the drain has a connection to a vacuum pressure.

[0029] Example 26 includes the subject matter of Example 25 where the vacuum pressure is actively monitored and adjusted to suit one or more examples.

[0030] Example 27 includes any of the subject matter of Example 19 where a pivotally attached reservoir is constructed and arranged to be pivotally actuated hydraulically.

[0031] Example 28 includes the subject matter of Example 27 where the fluid power is provided by the same hydraulic pressure source as at least one of at least two fluid supply lines.

[0032] Example 29 includes the subject matter of Example 19 where the film recovery mechanism includes a recovery frame, a recovery frame holder, a recovery frame holder track, and a recovery frame controller.

[0033] Example 30 includes the subject matter of Example 29 where the recovery frame holder holds the recovery frame and maintains the recovery frame at an inclination angle from the horizontal selected from 3 degrees to 177 degrees, preferably at an angle from the horizontal selected from 85 degrees to 95 degrees, or in a vertical position.

[0034] Embodiment 31 incorporates the subject of Embodiment 29, wherein the recovery frame holder track includes, in order, a first end, a straight section, an extension section, and a second end opposite the first end. The first end of the recovery frame holder track is positioned at a distance from the reservoir bottom. The second end of the recovery frame holder track is connected to or adjacent to devices for further film processing, such as storage space, film transfer devices for transferring the majority of the film to new frames, quality control analyzers, film coating devices, film annealing devices, or a combination thereof. The straight section of the recovery frame holder track may be in a vertical position or at an angle from the horizontal between 25 and 165 degrees. The extension section of the recovery frame holder track may have a straight, curved, inclined, or downward design for transporting recovery frames from the filtration device to any other analyzers and film processing devices.

[0035] Example 32 includes the subject of Example 29, wherein the recovery frame has: 1) a closed central opening whose shape accommodates and accepts a film based on the design of at least one opening in the floor or bottom of the reservoir, so as to cover the closed central opening; 2) at least one flange for attachment to a recovery frame holder; and 3) one side of the recovery frame selected for initial adhesion of a suspended layer of nanofibers without any obstruction (the design ensures that the flange does not obstruct such initial adhesion).

[0036] Example 33 is a method for preparing a nanofiber film, comprising: placing a filter at the bottom of a reservoir; filling the reservoir with a nanofiber suspension and fluid; filtering at least a portion of the nanotube suspension through at least one opening at the bottom of the reservoir by opening the reservoir drain, with or without vacuum assistance connected to the drain; removing nanofibers from the diluted suspension using the filter, wherein the filter is in communication with the reservoir drain; and forming a nanofiber film (also called a nanofiber layer, nanotube layer, or nanotube film) on the surface of the filter.

[0037] Example 34 includes the subject matter of Example 33 and further includes tilting the filter, or tilting the filter together with the bottom of the reservoir.

[0038] Example 35 includes the subject matter of Example 34 and further includes separating a nanofiber film from a filter.

[0039] Example 36 incorporates the themes of Examples 33-35, wherein a fluid is used to separate the nanofiber film from the filter.

[0040] Example 37 includes the subject matter of Example 36, wherein the fluid used to separate the nanofiber film from the filter is the same fluid used to dilute the nanofiber suspension during the filtration process.

[0041] Example 38 includes the subject matter of Example 36 and further includes suspending the nanofiber film on the surface of the fluid after the nanofiber film has been separated from the filter.

[0042] Example 39 incorporates the subject matter of Example 34, wherein by tilting, the fluid can impact the nanofiber film from the lowest point of the nanofiber film as the fluid surface rises, thereby changing the hydrophobic-hydrophilic interface between the nanofiber film and the filter.

[0043] Example 40 includes the subject matter of Example 33, and further includes immersing a nanofiber film on a filter in a fluid at an angle from the horizontal, wherein the immersion imparts an impact to the nanofiber film at the fluid surface from the lowest point of the nanofiber film.

[0044] Example 41 includes the subject matter of Example 40, wherein the fluid used for separation may be the same fluid used for the filtration process.

[0045] Example 42 includes the subject matter of Example 34 or Example 40, wherein either tilting or immersing the nanofiber film and filter causes them to shift from a horizontal plane to a minimum of 3, 5, 10, 15, 20, 25, or 30 degrees (tilt angle) from the horizontal.

[0046] Example 43 includes the themes of Examples 35-42 and further comprises suspending the nanofiber film separated from the filter and raising (or ascending) it to the top of the reservoir.

[0047] Example 44 incorporates the subject matter of any of the prior examples 33 to 43 and further includes depositing the nanofiber film on the recovery frame by submerging the recovery frame in an upright position below the fluid surface without disturbing the suspended nanofiber film; positioning the recovery frame by moving the recovery frame beneath the nanofiber film across a portion of the nanofiber film; and lifting the recovery frame to allow initial adhesion between the top surface of the recovery frame and the nanofiber film, and subsequent adhesion of the nanofiber film to the sides of the recovery frame having a central opening until the recovery frame is above the fluid surface and exits the reservoir.

[0048] Example 45 includes the subject matter of Example 44, wherein the upright position of the recovery frame may include an angle of 30 to 150 degrees from the horizontal, preferably 85 to 95 degrees, or 90 degrees.

[0049] Example 46 includes the subject matter of any of the prior examples 1 to 45 and further includes at least one nanofiber analysis device.

[0050] Example 47 includes the subject of Example 47, wherein the nanofiber analysis device is selected from a Raman spectrometer, a particle analyzer, or a particle monitor, or a combination thereof.

[0051] Example 48 includes the subject matter of any of Examples 1 to 45 and further includes at least one nanofiber film analyzer.

[0052] Example 49 includes the subject matter of Example 48, wherein the nanofiber film analyzer is selected from a nanofiber film strength analyzer, a film deflection measuring device, a film deflection adjustment device, a film electrical resistance measuring device, a light transmission measuring device whose optical spectrum is selected from 1 nm to 1 mm, a light transmission mapping device, a light transmission map analyzer, a UV-Vis spectrometer, a Fourier transform infrared spectrometer, or a combination thereof.

[0053] Example 50 includes the subject matter of any of Examples 1 to 45 and further includes a nanofiber or nanofiber film processing device.

[0054] Example 51 includes the subject matter of Example 50, wherein the nanofiber or nanofiber sheet processing device is selected from a film strength adjustment device, an annealing device, a coating device, or a combination thereof.

[0055] Example 52 includes the subject matter of Example 51, wherein the coating device is grown using physical vapor deposition or chemical vapor deposition.

[0056] Example 53 includes the subject matter of any of Examples 1 to 45 and further includes a HEPA filtration system.

[0057] Example 54 includes a humidity monitoring system and a humidity control system, and incorporates the subject matter of any of Examples 1 to 45.

[0058] Example 55 includes a thermostat and a temperature control system, and incorporates the subject matter of any of Examples 1 to 45.

[0059] Example 56 includes the subject matter of Example 2, wherein nanofibers are filtered from a suspension, the suspension containing water and nanoparticles, the nanoparticles being impermeable to the filter, and forming a composite layer on the surface of the nanofibers.

[0060] Example 57 incorporates the themes of Examples 1 to 45, wherein the filtered nanofiber film has at least two regions with different nanofiber densities in each region.

[0061] Example 58 incorporates the themes of Examples 1-45 and 57, wherein two or more filtered nanofiber films are laminated together.

[0062] Example 59 includes the subject of Example 58, wherein each nanofiber film in the laminate covers at least a portion of the central opening of the recovery frame.

[0063] Example 60 includes the themes of Examples 1-45, wherein at least two fluid supply lines may be combined into a single common-end fluid supply line, and the end of the single common-end fluid supply line is located above or inside the liquid reservoir.

[0064] Example 61 includes the subject matter of all the above examples, wherein the nanofiber film is a nanofiber pellicle film.

[0065] Example 62 includes the subject matter of Example 61, wherein the nanofiber pellicle film is a nanofiber extreme ultraviolet lithography film (nanofiber EUV pellicle film). [Brief explanation of the drawing]

[0066] [Figure 1] This is a side view of one embodiment of the apparatus described herein. [Figure 2] This is another side view of another embodiment of the device shown in Figure 1, which is tilted at an angle (angle α). [Figure 3] A flowchart illustrating a process included in one embodiment of a method for fabricating nanofiber films is provided. [Modes for carrying out the invention]

[0067] The figures illustrate various embodiments of the present disclosure for illustrative purposes only. Many variations, configurations, and other embodiments will become apparent from the embodiments for carrying out the invention described below.

[0068] overview This specification describes several techniques and apparatus that can be used to manufacture nanofiber films, such as carbon nanotube films or boron nitride nanotube films. The techniques may be suitable for applications involving the manufacture of ultrathin nanofiber films, or specific to such applications. The films may have thicknesses of 20 nm or less, 40 nm or less, 100 nm or less, or 250 nm or less. The films may be square, circular, or other shapes. Each nanofiber film has various uses, such as a filter for removing particles and a pellicle film for extreme ultraviolet lithography (EUVL). Each nanofiber pellicle film or EUV pellicle film may have at least one layer of ultrathin nanotube film manufactured by filtration. The techniques can be fully automated, partially automated, or manual, and can be used to manufacture different types of films and to provide consistent films with reproducible composition and quality.

[0069] filtration In many techniques, water or other fluids are used to deposit nanofibers on a filter in a planar orientation, either in a random or arbitrarily defined pattern. The nanofibers are mixed with the fluid to form a nanofiber suspension. The fluid can pass through the filter, or is allowed to pass through the filter, resulting in at least one layer or nanofiber film remaining on the filter surface. The size, diameter, and / or shape of the nanofiber film may be determined by the size, diameter, and / or shape of the filter, as well as the bottom opening, preferably multiple openings, at the bottom or floor of the reservoir that structurally supports the filter, while the thickness of the nanofiber film is determined by the amount of nanofibers deposited on the filter. If the concentration of nanofibers dispersed in the fluid is known, the mass of nanofibers deposited on the filter can be determined from the amount of fluid passing through the filter. The nanofibers, including the nanofiber film, may be a mixture of different types of nanofibers. The nanotube film may be of a single type, or a combination of two, three, or more types, such as single-walled, double-walled, and / or multi-walled nanotubes. When different types of nanotubes are in the same suspension, the nanotubes are usually uniformly distributed throughout the nanotube film. In other embodiments, different types of nanotubes (or other materials) can be layered on a filter by passing a continuous batch of the suspension material through the filter.

[0070] separation The nanofiber film can be removed from the filter using any technique that does not damage the film. It has been found that a fluid, such as water, can be used to help separate the film from the filter. For example, a fluid flow can be directed to the interface between the nanofiber film and the filter to help separate and remove the nanofiber film from the filter. The fluid flow can be substantially laminar and its velocity can be limited to apply enough force to gently separate and remove the film from the filter without damaging the film. It has been found that this technique can be improved by essentially gravity-feeding the fluid to the interface and by adjusting the angle of the filter (and film) with respect to the fluid flow (e.g., water) so that the fluid does not collide with the film and / or filter at a 90-degree angle. For example, the filter can be tilted at an angle of 30°, or an angle selected from a range (not limited to 30°), to allow the fluid flow to separate the film from the filter more effectively.

[0071] Another separation method may rely solely on a rising fluid surface, for example, without directing the fluid to the interface between the nanofiber film and the filter. When the rising fluid surface reaches the lowest interface point between the nanofiber film and the filter, which can both be tilted, the nanofiber film begins to separate from the filter due to a change in the interface between the hydrophobic nanofiber film and the hydrophilic film brought about by the nanotubular film and the fluid (e.g., water), or vice versa. Further separation of the remaining nanofiber film from the filter is achieved by injecting additional fluid. A constant and stable injection rate of the fluid can avoid fine wrinkles, very small folds, and visible creases in the nanofiber film, especially when the nanofiber film is an extremely thin nanotubular film. After the nanofiber film has been completely removed from the filter, it is desirable to keep the floating nanofiber film stationary on the fluid surface for recovery. The recovery step may also be initiated when the nanofiber film is almost completely removed. The recovered nanofiber films may be treated to enhance their mechanical properties, resistance to mechanical stress, or even resistance to chemical damage, for example, by adding a metal or metal oxide coating layer (or other material), or by annealing using energy selected from various sources. In deep ultraviolet lithography or extreme ultraviolet lithography, chemical damage can be caused by hydrogen plasma etching. The nanofiber films can then be optionally moved from one frame to another, or dried and / or stored using several processes, always handling them gently to avoid damage.

[0072] Embodiments of the present invention include the apparatus described in detail in Figure 1. The reservoir 100 may be a container, which may have any shape, including the cylindrical or rectangular prism (not shown) shape shown. The reservoir 100 may have a generally flat surface at its bottom or base for filtration purposes. The bottom of the reservoir 100 may not be flat, based on design or other design choices. The reservoir 100 may have an open top. The reservoir 100 may also include a plurality of openings 101 at its bottom, which may be integral. The reservoir 100 may have a replaceable bottom plate having a plurality of holes (openings 101), which may be part or all of the bottom. The reservoir 100 may also be provided with a drain 102 connected to the bottom of the liquid reservoir, as shown. In Figure 1, as shown, the drain 102 is connected to the opening 101 at the center of the bottom of the reservoir 100, but may be located in other preferred locations. The opening 101 may be completely covered with a replaceable filter before the start of the filtration process to ensure a uniform filtration flow rate during the filtration process and to avoid an uneven distribution of non-filterable particles or substances passing through the opening 101 in the reservoir 100. The drain 102 may be provided with a vacuum connection 103 connected to a vacuum pressure to facilitate the filtration process. The supply of vacuum pressure to the drain 102 is controlled by a vacuum pressure regulator (not shown). A closure (not shown) may be provided to prevent fluid from flowing out of the reservoir 100 through the drain 102. The closure may be, for example, a valve or a sliding cover, a pivotable cover, or a hinged cover. Opening the closure allows fluid to pass through the replaceable filter, while closing the closure prevents fluid from flowing out of the reservoir 100. The closure may generally be installed before the connection to the vacuum pressure to assist the filtration process. The replaceable filter may be a microporous porous membrane that retains nanofibers while allowing the flow of non-nanofiber components of the fluid to pass through.At least two fluid supply lines may be constructed together (for example, by combining two lines with an internal partition to form a single line so as to keep two different fluids separate, or by joining two lines to form a common line with a common end) or separately, and installed above or inside the reservoir 100 to provide fluid communication between the inside and outside of the reservoir 100. Tubes 150 and 151 schematically show the ends of at least two fluid supply lines. They may be outside the reservoir 100, and their outlets may be located above the open top of the reservoir 100. Alternatively, they may be incorporated into the wall of the reservoir 100. In different embodiments, 0, 1, 2, 3, or more nozzles may be included within one or more fluid supply lines. The fluid may be supplied gently, minimizing the impact on the film and / or filtration process that may be suspended on the surface of the fluid. For example, fluid can be supplied at flow rates exceeding 0.01, 0.1, 1, 2, 5, or 10 liters per minute while maintaining a linear velocity to the reservoir of less than 10 cm / s, less than 5 cm / s, less than 1 cm / s, or less than 0.5 cm / s. The fluid flow velocity may change during the reservoir refilling process and the nanofiber film separation process. The fluid supply line may be configured such that the fluid flows directly into the container of reservoir 100 through an orifice, or flows downward along the inner surface of reservoir 100.

[0073] At least one of the two fluid supply lines can carry the nanofiber suspension, while the second fluid supply line can perform fluid injection. The injected fluid may be any suitable liquid, including but not limited to water.

[0074] At least two fluid supply lines, each carrying either a nanofiber suspension or an injection fluid, may be combined into a single common terminal fluid supply line, the end of which is located above or inside the reservoir 100.

[0075] After the nanotube layer is formed on the filter covering the opening 101, the nanofiber film can be separated from the filter and moved out of the reservoir 100.

[0076] The nanofiber film can be separated from the filter by peeling it off. This can be facilitated by a fluid flow. For example, the fluid flow can be reversed through the filter so that the film is pushed upwards from the filter.

[0077] In a preferred embodiment, fluid is flowed between the filter and the nanofiber film to remove the nanofiber film from the filter while the bottom of the reservoir 100 maintains its horizontal level or is tilted at a certain angle (<90°) to face the direction of the fluid flow inflow. The fluid flow can separate the nanofiber film from the filter. However, this approach may increase the risk of damaging the nanofiber film, particularly the layer of ultrathin nanotube film. The nanofiber film may remain above the fluid surface and float to the top of the reservoir 100 as the fluid surface level rises.

[0078] By tilting the bottom of the reservoir, a fluid such as water can flow down along the inner wall of the reservoir 100 to the bottom of the reservoir 100. Other means may be provided for gently and / or continuously refilling the reservoir 100, starting from the lowest point of the nanofiber film, until it is completely separated, in order to separate the nanofiber film from the filter. The nanofiber film may be maintained on the surface of the fluid for the next recovery step.

[0079] The reservoir 100 can be tilted by pivoting it at one edge. The tilting of the reservoir 100 can be done manually, mechanically, or automatically. As shown in Figure 2, the angle between the floor surface and the horizontal surface of the reservoir 100 (or filter or nanofiber film) is called the inclination angle (angle α). In this specification, this angle may be referred to as the inclination angle. The inclination angle may be 3° or more, 5° or more, 10° or more, 15° or more, 20° or more, 25° or more, or 30° or more. In these and other embodiments, the inclination angle may be 60° or less, 50° or less, 40° or less, or 30° or less.

[0080] Separation of the nanofiber film from the filter may require immersing the nanofiber film on the filter in a fluid. Reservoir 100 may be refilled with a sufficient level of fluid before the start of separation. Another reservoir of appropriate size and shape may be selected as a substitute. The fluid may be the same as or different from the fluid used during filtration. During this process, the filter may make an angle from the horizontal plane, as shown by angle α in Figure 2. This angle may be 3° or greater, 5° or greater, 10° or greater, 15° or greater, 20° or greater, 25° or greater, or 30° or greater. In these and other embodiments, the inclination angle may be 90° or less, 50° or less, 40° or less, or 30° or less. Separation begins when the lowest point of the nanofiber film contacts the surface of the fluid and continues until the nanofiber film is completely removed from the filter. Separation may proceed at a controlled pace and / or constant pace to avoid the possibility of damage, creases, or folds to the nanofiber film. The nanofiber film is ready for recovery when the film has been completely or almost completely separated from the filter.

[0081] collect Figure 1 also includes a recovery frame 120, a recovery frame holder (122), and a recovery frame holder track 124.

[0082] The recovery frame holder 122 holds the recovery frame 120 in a vertical position, or at an angle ranging from 30 to 150 degrees from the horizontal position.

[0083] The lower portion of the recovery frame holder track 124 is shown in Figure 1, with a gap between its end and the bottom of the reservoir 100. The lower portion of the track is preferably linear to guide the upward and downward movement of the recovery frame holder 122.

[0084] The recovery frame holder 122 may also move horizontally to assist in the initial adhesion of the nanotube film to the upper side (indicated as 126) of the recovery frame 120.

[0085] Figure 2 shows an exemplary embodiment of the cylinder shown in Figure 1. The cylinder is tilted at an angle α and is ready to separate the nanofiber film from the filter.

[0086] Figure 3 provides a flowchart illustrating one embodiment of method 1000 for producing a filtration nanofiber film. The apparatus used is similar to or identical to that described herein and can be mounted on a surface at any height, or optionally, on a surface at arm or eye level for easy monitoring.

[0087] Process 1001 of Method 1000 is to install a porous filter at the bottom of the reservoir. The selected filter should be impermeable to nanofibers and optionally to desired nanoparticles. The selected filter should be permeable to fluids, optionally to selected surfactants and all undesirable particles. The filter may cover all holes or openings at the bottom of the reservoir to allow for a uniform flow and self-smoothing process of nanofibers during the filtration process.

[0088] Process 1005 provides a source of nanofibers for the production of nanotube films. In this example, Process 1005 includes providing a fluid (e.g., water) and a suspension of carbon nanotubes (CNTs), boron nitride nanotubes (BNNTs), graphene, any graphene derivative, or selected nanofibers in a fluid carrier. Such suspensions may further contain nanoparticles in various shapes, such as spheres, rods, cubes, and any other geometric shapes, with sizes ranging from 1 nm to 100 nm, 1 nm to 1 μm, or 100 nm to 2.5 μm. Common nanoparticles may include, but are not limited to, metals, metal particles (Au, Ag, Pt), metal oxides, polymers, colloidal polymers, and biopolymers.

[0089] In the case of nanotubes, they can be monolayered, bilayered, multilayered, or mixtures thereof. In one embodiment, the suspension can be prepared by first mixing nanotube powder with an aqueous solution. Optionally, a surfactant may be added to the suspension. The suspension of nanotubes and surfactant is centrifuged to remove nanotube aggregates. The supernatant is collected and stored as a nanotube suspension or nanotube suspension raw material. Water can be added to prepare a nanotube suspension raw material of a predetermined final concentration.

[0090] This nanofiber suspension can be passed through a filter of appropriate size to capture the nanofibers, while simultaneously allowing the liquid and surfactant of the suspension and suspension diluent to pass through, thereby forming a filtered nanofiber film (process 1010). The amount of suspension to be filtered depends on the concentration of nanofibers in the suspension and the desired density of the final filtered nanofiber film. The density of the final filtered nanofiber film is important for ultrathin filtered films. An example density is 1.0 cm². 2 Less than 8.0 μg of carbon nanotubes (8.0 μg / cm³) deposited over an area 2 Less than 3.0 μg / cm³ 2 Less than 0.65 μg / cm³ 2 Less than 0.10 μg / cm³2 The density may be higher. The amount of material passing through the filter can vary from a few milliliters to several liters of fluid, depending on the amount of nanofibers to be deposited. In some cases, 10 mL or more, 50 mL or more, 100 mL or more, 1.0 L or more, or 10 L or more of the suspension may pass through the filter. The volume velocity of the suspension (filtrate) passing through the filter may be 100 μl / s or more, 1.0 ml / s or more, 5.0 ml / s or more, 10 ml / s or more, 100 ml / s or more, 200 ml / s or less, 100 ml / s or less, 10 ml / s or less, or 1.0 ml / s or less. The filtrate generally refers to any substance, object, or mixture that passes through the filter. The filtrate in one embodiment of this disclosure may be selected from, but is not limited to, a nanofiber suspension, a concentrated nanofiber suspension or its raw materials, a fluid for diluting any nanofiber suspension, one or more nanoparticles, one or more surfactants, or a combination thereof. The filtrate, after passing through the filter, can be discarded, recycled to create another nanofiber suspension, or reused when forming a filtration film.

[0091] The filter (or at least its upper surface) is inherently hydrophilic, or can be hydrophilically treated, because the nanofiber film is inherently hydrophobic. Hydrophilic treatment includes, for example, O2 plasma, corona treatment, O3 treatment, or other means of increasing the hydrophilicity of the filter surface.

[0092] After draining the suspension from the reservoir, the reservoir is tilted (process 1015), and water is added to refill the reservoir. Subsequently, process 1020 is performed to separate the nanofiber film from the filter.

[0093] Refilling involves raising the liquid level, thereby removing the newly formed nanofiber film, which then floats on the fluid surface as the fluid continues to refill the reservoir. For example, refilling can be achieved by controlling the rate at which the fluid is added to the reservoir, thereby controlling the buoyancy of the nanofiber film on the fluid surface.

[0094] To facilitate removal, the fluid flow can be directed to the interface between the nanofiber film and the filter.

[0095] To further facilitate removal, the filter or reservoir may be tilted at an angle of 3 degrees or more from the horizontal plane during the fluid refilling process. As the fluid surface rises, the nanofiber film may begin to detach from the filter at its lowest point when tilted. Further refilling may eventually completely separate the nanofiber film from the filter, allowing it to rise to the top of the reservoir for final recovery (process 1025).

[0096] The newly formed nanofiber film on the filter may be immersed in the fluid at an angle from the horizontal plane, the range of which is equal to the inclination angle of the reservoir. In this stepwise immersion process, the nanofiber film may be separated from the filter, starting from the lowest point of the nanofiber film, until it is completely or nearly completely separated for the next recovery step (process 1025).

[0097] Attachments may be added (not shown) to cover two or more layers of the filtration-generated nanofiber film to create a pellicle film.

[0098] To eliminate potential particulate contamination of any nanotube film, HEPA filters and / or filtration systems can be incorporated into nanotube film manufacturing systems and methods.

[0099] For humidity control, a humidifier and a humidity control subsystem are optionally included.

[0100] To further ensure consistent quality and mechanical strength of the manufactured nanofiber film, a thermostat and temperature control system may be included to control the ambient temperature and / or fluid temperature.

[0101] Add-on devices One embodiment of the present disclosure includes at least one nanofiber analysis device or instrument.

[0102] Another embodiment of the present disclosure includes at least one nanofiber sheet analysis device or instrument.

[0103] Further embodiments of the present disclosure, though not limited to them, include processing or preparation devices for nanofiber films and methods for processing nanofiber films.

[0104] Nanofiber film analysis devices, processing devices, or preparation instruments may be standalone devices. Two or more devices selected from analysis devices, processing devices, and preparation instruments can be combined and incorporated into a single large device or system. Further connections of these devices described herein, by engineering principles, enable roll-to-roll processes and create a possible system or two or more subsystems that are highly adaptable, flexible, easy to operate, durable, and sustainable for mass production.

[0105] One example of such a device is a light transmission measurement device. This device emits light of a wavelength selected from 1 nm to 1 mm as incident light. The device has a detector in either the direct or reflected path of the emitted light to quantify the amount of light that has passed through a nanofiber film (transmitted light). The ratio of the transmitted light intensity to the incident light intensity is expressed as a percentage, known as the light transmittance.

[0106] By performing numerous measurements across the entire nanofiber film, multiple transmittances can be obtained. These can be used to generate a light transmission map, which can then be used with analytical tools or software to indicate the uniformity or variability of the film density. The film density variation can be expressed as a percentage or other data format by considering the maximum, minimum, average, and median light transmission values ​​and the repetition of individual values. The porosity of the film can be detected and adjusted using known devices and methods.

[0107] The light scattering of nanofiber films can be measured alone or in combination with light transmission tests. For nanofiber films suitable for extreme ultraviolet (EUV) lithography applications, the EUV scattering of EUV pellicle films is measured at an angle of 4.7 degrees, according to current industry standards. EUV scattering or other light scattering can be measured at different angles ranging from -90 degrees to +90 degrees.

[0108] Another embodiment of the present disclosure includes one or more devices for measuring the mechanical strength and Young's modulus of a nanofiber film. Based on the results, the properties of the nanofiber film may be tuned by a separate device that stretches the nanofiber film in at least one direction while maintaining the film intact, in order to fine-tune the mechanical strength of the film.

[0109] The electrical resistance of nanofiber films can be quantified by known methods and apparatus.

[0110] To determine the physical and chemical properties of additional nanofibers and nanofiber films, Raman spectrometers, Fourier transform infrared spectrometers, ultraviolet-visible spectrometers, or combinations thereof may be used, which are well known techniques.

[0111] Another embodiment is a nanofiber film deflection measuring device or bulge test apparatus. In this test, a nanofiber film is attached to a flat boundary surface to establish a baseline for the nanofiber film. An initial flow of any gas, preferably an inert gas, is applied at a low steady pressure, perpendicularly to the central region of the nanofiber film, causing the central portion of the nanofiber film to rise. The distance from the baseline to the highest point of the deflected film is measured and recorded as deflection. During the test, the flow velocity or flow pressure of the applied gas may be increased until the nanofiber film bursts (burst test), and the burst gas pressure or flow pressure is recorded. The applied gas pressure may have values ​​of 2 Pascals (2 Pa), less than 10 Pa, or less than 20 Pa. The gas flow velocity may be a value selected from less than 5 mbar / sec, less than 3.5 mbar / sec, less than 10 sccm, or less than 8 sccm, and can be expressed in mbar / sec or sccm.

[0112] The flexibility properties of nanofiber films can be adjusted according to prevailing industry standards by one or more apparatuses or methods, including but not limited to heating, cooling, and mechanical stretching, or by electric current, energy convection, conduction, or radiation of electromagnetic wavelengths.

[0113] An annealing device can be incorporated as one embodiment for general nanofiber film cleaning purposes or for increasing EUV transmission. The annealing device can utilize an electric current, laser, infrared, or microwave energy source, or convection or radiation of electromagnetic wavelengths from 10 nm to 1 mm. The annealing process is carried out in a vacuum or inert gas environment at a selected temperature or temperature range. The annealing temperature can be selected from the range of 50°C to 3,000°C. Common inert gases applicable to annealing include, but are not limited to, nitrogen, argon, helium, xenon, or combinations thereof.

[0114] Nanofiber films may be coated with nanoparticles or treated with gas using a known coating apparatus or gas chamber to improve the lifespan of the nanofiber film.

[0115] Nanoparticles may include metals or metal oxides selected from, but not limited to, Au, Ag, Zr, Mo, Ru, Pt, Cr, W, Cr, Ni, Co, or combinations thereof.

[0116] The nanoparticles may further contain O, N, Si, H, SiC, or combinations thereof.

[0117] The gas can be selected from methane, ethane, ethene, propane, propene, or a combination thereof.

[0118] The coated devices may be deposited by physical vapor deposition or chemical vapor deposition (CVD). Exemplary deposition methods include, but are not limited to, electron beam deposition, evaporation deposition, sputter deposition, thermal laser epitaxy, sublimation, plasma-enhanced CVD, microwave-assisted CVD, and atomic layer deposition (ALD).

[0119] To meet stringent EUV lithography pellicle requirements, a particle counting device may be included to measure elemental values ​​at any point during the manufacturing of the nanofiber film to identify potentially undesirable particles or contaminants.

[0120] Another embodiment of the present disclosure also includes a nanofiber film transfer device. An exemplary transfer device includes a receiving frame and a receiving mechanism for receiving nanofiber films from a donor film. An exemplary transfer method includes adhering the donor film on a first frame to a second frame, and then removing the first frame and excess nanofiber film by physical cutting or laser cutting. The transfer method may optionally involve applying an adhesive or a low-adhesion adhesive to the surface of the second frame.

[0121] One embodiment of the present disclosure further includes a nanofiber film dryer for performing air drying, heat drying, radiation drying, or a combination thereof.

[0122] Properties of useful nanotubes and filter films Carbon nanofiber structures are generally formed from at least one of the following: multi-walled carbon nanotubes (MWCNTs), double-walled carbon nanotubes (DWCNTs), or single-walled carbon nanotubes (SWCNTs). Boron nitride nanotubes (BNNTs), an analogue of carbon nanotubes, also exist. Other forms of nanofibers include coaxial carbon nanotubes, conical carbon nanotubes, and closed carbon nanotubes. The processes used to form pure multi-walled carbon nanotubes (e.g., carbon nanotubes with 3 to 20 concentric walls and diameters ranging from 4 nm to over 100 nm), double-walled carbon nanotubes (e.g., carbon nanotubes with two concentric walls and diameters ranging from 1.6 nm to 6 nm), and single-walled carbon nanotubes (e.g., one wall and tube diameters ranging from 0.2 nm to 4 nm) can differ from one another. For example, multi-walled carbon nanotubes can be manufactured using a chemical vapor deposition (CVD) process on a relatively thick catalyst layer (e.g., 10 nm to several microns thick) on a substrate, while two-walled and single-walled carbon nanofibers are often formed using laser ablation, carbon arc processes, or chemical vapor deposition (e.g., using acetylene or ethane as precursors) on a thin (e.g., 0.2 nm to 10 nm thick) and potentially discontinuous catalyst layer across the entire substrate. Laser ablation generally produces shorter carbon nanotubes and nanotubes with fewer crystal defects than those produced by chemical vapor deposition. For at least this reason, processes used to manufacture one type of nanofiber generally do not produce measurable amounts of other types of nanofibers.

[0123] These three different types of carbon nanotubes each have different properties. For example, double-walled and single-walled carbon nanotubes can be more conveniently dispersed in a solvent for subsequent formation of sheets of randomly oriented carbon nanotubes (i.e., most of the nanotubes are suspended separately and not adsorbed onto other nanotubes). As a result of this uniform dispersion of individual nanotubes in the solvent, it is possible to produce a more dimensionally uniform nanotube film formed by removing the solvent from the suspended nanofibers. A nanofiber sheet with this configuration is called a filter film. This physical uniformity (which can be further improved by stacking multiple filter films on top of each other) can also improve the uniformity of properties across the film (e.g., transparency to irradiation).

[0124] The strength of van der Waals attractive forces between nanofibers also differs between single-walled and / or double-walled nanofibers and multi-walled nanofibers. Generally, single-walled and / or double-walled nanofibers have greater van der Waals attractive forces to each other than those observed in multi-walled nanofibers. This increased attractive force between single-walled and / or double-walled nanofibers can improve the ability of single-walled and / or double-walled carbon nanotubes to adhere to each other and form cohesive nanofiber structures such as filter films. Sheets or films formed from single-walled and / or double-walled carbon nanotubes can better fit to the topography of supporting structure surfaces at smaller dimensions than sheets or films formed from multi-walled carbon nanotubes. In some examples, sheets or films formed from single-walled and / or double-walled carbon nanotubes can fit to the topography of small substrates of about 10 nm, which is at least 50% smaller than the characteristic size to which films of multi-walled carbon nanotubes can fit. In some cases, multi-walled carbon nanotubes are more likely to aggregate with each other than single-walled and / or double-walled nanotubes, thereby creating structurally heterogeneous films that are less likely to fit and / or adhere to the surface of the supporting structure.

[0125] Filtration films, particularly those made from single-layer and / or double-layer carbon nanotubes, also generally exhibit higher transparency to irradiation at certain wavelengths. In some examples, the transmittance of incident radiation can reach 88%, 90%, or 95%, and sometimes even 99%, in the visible, UV, and extreme UV ranges. In some cases, this transmittance is significantly higher than that of stretched sheets of multi-wall carbon nanotubes. Filtration films can function as filters for particle removal and water filtration membranes. Ultrathin filtration films can function as EUV pellicle films.

[0126] nanofiber As used herein, the term “nanofiber” means a fibrous or tubular material measured in diameter or thickness of less than nanometers or 1 μm. Although the embodiments herein are described primarily as being made from carbon nanotubes, it will be recognized that other allotropes of carbon, whether graphene, micron- or nanoscale graphite fibers and / or plates, and other compositions of nanoscale fibers such as boron nitride nanotubes, can also be starting materials for the techniques described herein. As used herein, the terms “nanofiber” and “nanotube” are used interchangeably and both encompass single-walled carbon nanotubes, double-walled carbon nanotubes, and / or multi-walled carbon nanotubes (where carbon atoms are linked to each other to form a cylindrical structure). Nanofibers and nanotubes also include the corresponding boron nitride materials. In some embodiments, the multi-walled carbon nanotubes referred to herein have 3 to 20 walls. Double-walled carbon nanotubes have 2 walls.

[0127] The dimensions of carbon nanotubes can vary significantly depending on the production method used. For example, the diameter of a carbon nanotube can range from 0.4 nm to 100 nm, and its length can range from 10 μm to over 55.5 cm. Carbon nanotubes can also have extremely high aspect ratios (length-to-diameter ratios), such as or even higher than 132,000,000:1. Considering the various dimensional possibilities, the properties of carbon nanotubes are highly tunable or "tunable." While many interesting properties of carbon nanotubes have been identified, utilizing these properties in practical applications requires scalable and controllable manufacturing methods that allow for the maintenance or improvement of carbon nanotube characteristics.

[0128] One source of carbon nanotubes is by growing nanotube forests on a catalytic substrate. A method for producing nanofiber forests is described, for example, in PCT No. WO2007 / 015710, which is incorporated herein by reference in its entirety.

[0129] Suspension and film properties Dry carbon nanotubes can be mixed with a solvent to uniformly disperse the nanotubes in the solvent, thereby forming a suspension. Mixing methods include mechanical mixing (e.g., using an electromagnetic stirring rod and stirring plate), ultrasonic stirring (e.g., using an immersion ultrasonic probe), or other means. In some examples, the solvent can be a protic or aprotic polar solvent, such as water, isopropyl alcohol (IPA), N-methyl-2-pyrrolidone (NMP), dimethyl sulfide (DMS), or a combination thereof. In some examples, a surfactant may be included to facilitate the uniform dispersion of carbon nanofibers in the solvent. Exemplary surfactants, but not limited to, include sodium cholate, sodium dodecyl sulfate (SDS), and sodium dodecylbenzenesulfonate (SDBS). The weight percentage of the surfactant in the solvent can be anywhere between 0.1% and 10% by weight of the solvent. In another embodiment, a mixture of 50% by weight of multi-walled carbon nanotubes and 50% by weight of single-walled carbon nanotubes can be prepared and suspended in water and the SDS surfactant. In another embodiment, a mixture of 25% by weight of single-walled carbon nanotubes and 75% by weight of double-walled carbon nanotubes can be prepared and suspended in water and an SDS surfactant. In yet another embodiment, a mixture of 50% by weight of single-walled carbon nanotubes and 50% by weight of double-walled carbon nanotubes can be prepared and suspended in water and an SDS surfactant. In yet another embodiment, a mixture of 50% by weight, up to 80%, of double-walled carbon nanotubes and the remaining proportion of single-walled and multi-walled carbon nanotubes can be prepared and suspended in water and an SDS surfactant.

[0130] The concentration of nanotubes in the suspension may vary depending on the type of nanotube and the desired properties of the resulting membrane. In different embodiments, nanotube suspensions may be prepared at weight / weight concentrations of 5% or more, 1% or more, 0.1% or more, 100 ppm or more, 10 ppm or more, or 1.0 ppm or more. Specific ranges include 0.1–100 ppm, 1–100 ppm, 1–1000 ppm, and 10–10,000 ppm. The suspension can be developed from a masterbatch (nanotube suspension raw material) containing a high concentration of carbon nanotubes. For example, the masterbatch may contain 0.1% or more, 1% or more, 2% or more, or 3% or more by weight / volume of nanotubes in the solvent. More diluted suspensions may have greater stability, and in some cases, for example, suspensions of 100 ppm or less may remain stable for longer periods than 1 minute, longer than 1 hour, or longer than 5 hours. The diluted suspension can be prepared from the masterbatch using the same solvent or a different solvent as that used in the masterbatch.

[0131] In some other exemplary embodiments, the suspension material may include non-nanotubular materials, other carbon-based materials, or nanofibers. These include, but are not limited to, graphene, graphene oxide, amorphous graphene, fullerenes, various nanofibers, or any derivatives, modified or functionalized versions of the aforementioned materials. These materials can form mesh-like interconnected networks, i.e., films, which can be prepared by commercially available equipment and robots incorporated herein.

[0132] Further consideration The foregoing description of embodiments of this disclosure is provided for illustrative purposes only and is not intended to be exhaustive or to limit the claims to the exact forms disclosed. Those skilled in the art will recognize that many modifications and variations are possible in light of the above disclosure.

[0133] The language used herein has been selected primarily for readability and illustrative purposes, and may not be chosen to describe or limit the subject matter of the invention. Therefore, the scope of this disclosure is intended to be limited not by the "Modes for Carrying Out the Invention" but rather by any claims arising in an application based on this specification. Accordingly, the disclosure of this embodiment is intended to illustrate, but not limit, the scope of the invention as set forth in the following "Claims."

Claims

1. An apparatus for manufacturing nanofiber pellicle film, A structural frame having a base, A reservoir having a bottom and multiple openings in the bottom, At least two fluid supply lines, the outflow terminals of which are located inside the reservoir, Recovery frame holder and A recovery frame holder track for guiding the movement of the recovery frame holder, A recovery frame controller for controlling the movement of the recovery frame holder, Equipped with, The reservoir is pivotably mounted to the base of the structural frame, and the reservoir is adjustable to an angle of inclination of at least 3 degrees from horizontal. The bottom portion has a drainage channel at its lower end, and the drainage channel communicates with the plurality of openings and is connected to a negative vacuum pressure. The first fluid supply line among the at least two fluid supply lines is configured to fill the reservoir with fluid. The second fluid supply line of the at least two fluid supply lines is configured to dispense a nanofiber suspension. The recovery frame holder is configured to maintain the recovery frame at an angle of 75 to 105 degrees from the horizontal, to submerge the recovery frame below the surface of the fluid, to attach a nanofiber pellicle film to the recovery frame, and to lift the recovery frame upward from inside the reservoir. The recovery frame holder track has one outer end of the reservoir and the opposite end having a straight portion longer than the length of the recovery frame, and the end of the opposite end is positioned at a distance from the bottom. The aforementioned device.

2. The amount of the nanofiber suspension dispensed was 0.1 μg / cm³. ２ ~8.0 μg / cm³ ２ The apparatus according to claim 1, wherein the apparatus is configured to produce a nanofiber pellicle film having a density between .

3. The apparatus according to claim 1, wherein the apparatus is configured such that the dispensing of the nanofiber suspension yields a nanofiber pellicle film having a thickness of less than 250 nm.

4. The apparatus according to claim 1, wherein the dispensing of the nanofiber suspension yields a nanofiber pellicle film having a thickness of less than 40 nm.

5. The apparatus according to claim 1, wherein the dispensing of the nanofiber suspension yields a nanofiber pellicle film having a thickness of less than 20 nm.

6. The apparatus according to claim 1, wherein at least one of the at least two fluid supply lines is attached to the structural frame.

7. The apparatus according to claim 1, further comprising an accessory selected from a light transmission measuring device, a light transmission mapping and analysis device, a light scattering measuring device, a nanofiber pellicle film strength measuring device, a nanofiber pellicle film strength adjustment device, a nanofiber electrical resistance measuring device, a nanofiber pellicle film deflection measuring device, a nanofiber pellicle film deflection adjustment device, a nanofiber pellicle film transfer device, a nanofiber pellicle film annealing device, a nanofiber pellicle film coating device, a nanofiber dryer, or a combination thereof.

8. A method for preparing a nanofiber pellicle film, The process involves filtering a nanofiber suspension onto a filter in a reservoir to generate a nanofiber pellicle film on the filter, wherein the filter has a horizontal planar orientation. The filter and the nanofiber pellicle film are tilted to a second plane having an inclination angle of at least 3 degrees from the horizontal, Filling the reservoir with fluid, The filter and the nanofiber pellicle film are immersed in the fluid to separate the nanofiber pellicle film from the filter. The nanofiber pellicle film is suspended on the surface of the fluid, Includes, The nanofibers within the nanofiber pellicle film are randomly oriented in a planar orientation on the filter surface. The aforementioned method.

9. The method according to claim 8, wherein the nanofiber suspension and the fluid include water.

10. The method according to claim 8, wherein the nanofiber is selected from carbon nanotubes, boron nitride nanotubes, graphene, graphene oxide, or a combination thereof.

11. The method according to claim 10, wherein the carbon nanotube is selected from single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, or a combination thereof.

12. The method according to claim 8, further comprising attaching the nanofiber pellicle film to the recovery frame and lifting the recovery frame from the fluid surface and removing it from the reservoir.

13. The method according to claim 12, further comprising drying the nanofiber pellicle film.

14. Dispense the nanotube suspension and add 0.1 μg / cm³. ２ ~8.0 μg / cm³ ２ The method according to claim 8, further comprising providing a nanotube pellicle film having a density between the above.

15. The method according to claim 8, further comprising dispensing a nanofiber suspension to obtain a nanofiber pellicle film having a thickness of less than 250 nm.

16. The method according to claim 8, further comprising dispensing a nanofiber suspension to obtain a nanofiber pellicle film having a thickness of less than 40 nm.

17. The method according to claim 8, further comprising dispensing a nanofiber suspension to obtain a nanofiber pellicle film having a thickness of less than 20 nm.

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