Self-supporting pellicle film with HARM structure

Abstract

A method for forming a self-supporting pellicle film having a high aspect ratio molecular structure is disclosed. [Solution] The self-supporting pellicle film is a self-supporting pellicle film having a high aspect ratio molecular structure (HARM structure) attached to a frame, and the self-supporting pellicle film with the HARM structure exhibits a transmittance difference value of 1% or less when calculated using the following formula: transmittance difference value (%) = maximum transmittance (%) - minimum transmittance (%), the maximum transmittance is the maximum value of the transmittance measured at a wavelength of 550 nm for the self-supporting pellicle film with the HARM structure, and the minimum transmittance is the minimum value of the transmittance measured at a wavelength of 550 nm for the self-supporting pellicle film with the HARM structure, and the self-supporting pellicle film with the HARM structure is 1 cm 2 Each contains 10 or fewer defects, and each defect has a size greater than 15 μm in at least one direction.

Description

Technical Field

[0001] The present disclosure relates to a method for forming a self-supporting pellicle film having a high aspect ratio molecular structure (HARM structure). The present disclosure further relates to a self-supporting pellicle film having a high aspect ratio molecular structure (HARM structure) attached to a frame. The present disclosure further relates to the use of the self-supporting pellicle film.

Background Art

[0002] Extreme ultraviolet lithography (EUV or EUVL: Extreme ultraviolet lithography) is an optical lithography technology using the 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 for EUV lithography acceptance. Therefore, sophisticated particle filters such as EUV pellicle films are required.

Summary of the Invention

Means for Solving the Problems

[0003] A method for forming a self-supporting pellicle film is disclosed. A method for forming a self-supporting pellicle film having a high aspect ratio molecular structure (HARM structure) comprises a) depositing a first portion of the HARM structure on a porous filter to form a film of the HARM structure on the porous filter; b) transferring the film of the HARM structure from the porous filter to a frame to form a self-supporting film of the HARM structure attached to the frame; c) depositing a second portion of the HARM structure on the self-supporting film of the HARM structure attached to the frame to form a self-supporting pellicle film of the HARM structure attached to the frame.

[0004] Furthermore, a self-supporting pellicle film having a high aspect ratio molecular structure (HARM structure) attached to a frame is disclosed. The self-supporting pellicle film with the HARM structure exhibits a transmittance difference value of 1% or less when calculated using the following formula. Transmittance difference value (%) = Maximum transmittance (%) - Minimum transmittance (%) Here, The maximum transmittance is the maximum value of the transmittance measured at a wavelength of 550 nm for a self-supporting pellicle film with a HARM structure. The minimum transmittance is the lowest transmittance measured at a wavelength of 550 nm for a self-supporting pellicle film with a HARM structure.

[0005] Furthermore, the use of a self-supporting pellicle film as an extreme ultraviolet film, as an extreme ultraviolet debris filter, or as a pellicle film for an X-ray window in extreme ultraviolet lithography is disclosed.

[0006] To facilitate a further understanding of the examples, the accompanying drawings, which are included and form part of this specification, illustrate the examples. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows a method for forming a self-supporting pellicle film with a HARM structure according to one embodiment. [Figure 2] This diagram shows the configuration of an optical measuring device for measuring transmittance. [Figure 3] This is a diagram showing a defective image. [Figure 4] This is a diagram showing a defective image. [Modes for carrying out the invention]

[0008] This disclosure relates to a method for forming a self-supporting pellicle film having a high aspect ratio molecular structure (HARM structure), wherein the method is a) In order to form a film of HARM structure on a porous filter, the step is to deposit a first portion of the HARM structure onto the porous filter, b) A step of transferring a film with a HARM structure from a porous filter to a frame in order to form a self-supporting film with a HARM structure attached to the frame, c) The step of depositing a second portion of the HARM structure onto the self-supporting film of the HARM structure attached to the frame in order to form a self-supporting pellicle film of the HARM structure attached to the frame.

[0009] In one embodiment, the first portion and / or the second portion of the HARM structure are deposited from the gas phase. In one embodiment, step a) is carried out by depositing the first portion of the HARM structure onto a porous filter from the gas phase in order to form a film of the HARM structure on the porous filter. In one embodiment, step c) is carried out by depositing the second portion of the HARM structure onto a self-supporting film of the HARM structure attached to a frame from the gas phase in order to form a self-supporting pellicle film of the HARM structure attached to a frame.

[0010] A porous filter can be used when depositing a HARM structure to form a layer or film of the HARM structure. The porous filter may be a nonwoven or woven filter. The porous filter may be made of mixed cellulose ester (MCE), polyethersulfone (PES), track-etched polycarbonate, electrospun fiberglass (PVDF), or polyethylene terephthalate (PET), polyamide, metal, or glass fiber. The material of the porous filter may be selected such that, for example, when the HARM structure is deposited on the porous filter from the gas phase, the HARM structure remains on the porous filter, thereby allowing the gas itself, i.e., the carrier gas, to be filtered by the porous filter.

[0011] Typically, porous filters, like most surfaces, have surfaces that are neither smooth nor defect-free, and may contain multiple defects in the form of small pores or nodules, as well as areas of high and low porosity. These porous filter defects can further affect the homogeneity of the film deposited on the porous filter. These defects can degrade the mechanical properties of the pellicle film and weaken its particle filtration capacity, for example, in particle filtration or EUV pellicle applications.

[0012] To reduce the heterogeneity of deposited films, efforts have typically been made to obtain filters with surfaces that are as smooth and defect-free as possible for deposition. However, the inventors unexpectedly discovered that by first depositing a portion of the HARM structure onto a porous filter, and then transferring the resulting HARM structure film to a frame, another portion of the HARM structure is deposited directly onto a self-supporting film of the HARM structure, defects in the resulting self-supporting pellicle film of the HARM structure can be efficiently reduced. Without being limited to any particular theory as to why a highly smooth self-supporting pellicle film of the HARM structure can be formed by the stepwise deposition of the HARM structure as disclosed herein, it can be considered that when a second portion of the HARM structure is deposited onto a self-supporting film of the HARM structure, thinner portions of the self-supporting film of the HARM structure can pass through more gas containing the HARM structure than thicker portions. This can result in a larger amount of HARM structure being deposited on or within possible defects in the self-supporting film of the HARM structure than on the rest of the film.

[0013] Unless otherwise noted, the term "defect" in this specification should be understood as micropores, thinner areas, indentations, pores, bumps, or areas of high and low porosity in the pellicle film.

[0014] This disclosure further relates to a self-supporting pellicle film having a high aspect ratio molecular structure (HARM structure) attached to a frame, wherein the self-supporting pellicle film of the HARM structure exhibits a transmittance difference value of 1% or less when calculated using the following formula. Transmittance difference value (%) = Maximum transmittance (%) - Minimum transmittance (%) Here, The maximum transmittance is the maximum value of the transmittance measured at a wavelength of 550 nm for a self-supporting pellicle film with a HARM structure. The minimum transmittance is the lowest transmittance measured at a wavelength of 550 nm for a self-supporting pellicle film with a HARM structure.

[0015] Transmittance can be measured using the optical measuring apparatus configuration shown in Figure 2, according to the following: The apparatus is calibrated to 100%T and 0%T. A frame with a pellicle attached is placed on a table between the LED light source and the collimating lens. The distance between the LED and the collimator is set to 5 cm, and the light spot size is approximately 3 mm. The LED type used is a Moonstone 3W High brightness Power LED light source (color temperature 4000K to 10000K, 110-degree viewing angle, product ASMT-MWE2-NNP00), and the spectrometer is an Ocean Insight STS-VIS-L-25-400-SMA (range: 350~800 nm). The %T (% transmittance) value is recorded.

[0016] To determine the transmittance difference value, the square centimeter (cm) of the sample is measured. 2 One %T measurement point is taken for each %). The measured maximum and minimum values ​​are used to calculate the transmittance difference value (%).

[0017] The present disclosure further relates to the use of the self-standing pellicle film disclosed herein as an extreme ultraviolet film, as an extreme ultraviolet debris filter, or as a pellicle film for an X-ray window in extreme ultraviolet lithography. In one embodiment, the self-standing pellicle film is a pellicle film such as an extreme ultraviolet film, an extreme ultraviolet debris filter, or a pellicle film for an X-ray window for extreme ultraviolet lithography.

[0018] The expressions "HARM structure" or "HARMS" shall be understood herein to refer to a "nanostructure", i.e., a structure having one or more characteristic dimensions on the nanometer scale, i.e., about 100 nanometers or less, unless otherwise stated. "High aspect ratio" refers to the degree to which the dimensions of a conductive structure in two perpendicular directions are significantly different in size. For example, a nanostructure may have a length that is tens or hundreds of times higher than its thickness and / or width. In a film of a HARM structure, a number of said nanostructures are interconnected with each other to form a network of interconnected molecules. Considered on a macroscopic scale, the HARMS network forms a solid monolithic material, where the individual molecular structures are disordered or unoriented, i.e., substantially randomly oriented or oriented. Various types of HARM structure networks can be produced in the form of a thin transmission layer having a reasonable resistivity. In one embodiment, the HARM structure is a conductive HARM structure.

[0019] In one embodiment, the HARM structure is a carbon nanostructure. In one embodiment, the carbon nanostructure includes carbon nanotubes, carbon nanobuds, carbon nanoribbons, or any combination thereof. In one embodiment, the carbon nanostructure includes carbon nanotubes and / or carbon nanobuds. A carbon nanobud, or a carbon nanobud molecule as they may also be called, has a fullerene or a molecule such as a fullerene covalently bonded to the side of a tubular carbon molecule.

[0020] In one embodiment, the method includes, prior to step a), forming or generating the HARM structure as an aerosol in the gas phase. That is, the HARM structure is first generated in the gas phase in a reactor and can then be deposited from that gas phase onto a porous filter or a free-standing film of the HARM structure, respectively. The deposition can thus be accomplished, for example, by allowing a gas stream, such as a carrier gas having the HARM structure, to pass through the porous filter or the free-standing film, whereby the HARM structure remains on the porous filter or the free-standing film, thereby forming a deposit of the HARM structure thereon. On the other hand, the carrier gas may pass through the porous filter or the free-standing film. The HARM structure may be deposited from the gas phase, for example, through filtration.

[0021] The deposition can be accomplished by passing a gas stream having the HARM structure through a porous filter or a free-standing film of the HARM structure at a total gas flow rate of 5 to 500 l / min. The gas flow rate may be, for example, 5 to 30 l / min, or alternatively 30 to 90 l / min, 40 to 80 l / min, or 50 to 70 l / min, or alternatively 90 to 500 l / min, 100 to 450 l / min, or 150 to 400 l / min. The higher the flow rate, the higher the throughput of the gas stream passing through the porous filter of the free-standing film of the HARM structure, thereby affecting the cost involved in the process.

[0022] In one embodiment, a free-standing pellicle film of the HARM structure exhibiting a transmittance difference value of 1% or less is formed when the following formula is calculated: Transmittance difference value (%) = Maximum transmittance (%) - Minimum transmittance (%), where the maximum transmittance is the maximum value of the transmittance measured at a wavelength of 550 nm for the free-standing pellicle film of the HARM structure, and the minimum transmittance is the minimum value of the transmittance measured at a wavelength of 550 nm for the free-standing pellicle film of the HARM structure.

[0023] In one embodiment, the self-supporting pellicle film of the HARM structure is 1 cm 2 Each contains 10 or fewer defects, 5 or fewer defects, 3 or fewer defects, 1 or fewer defects, or 0 defects. In one embodiment, the self-supporting pellicle film of the HARM structure is 1 cm 2 Each contains 0-10, 1-5, or 1-3 defects. As such, a defect may be considered to be a defect that is larger than 15 μm, 12 μm, 9 μm, 7 μm, 5 μm, 3 μm, 2.5 μm, 1.5 μm, 1 μm, 0.5 μm, 0.3 μm, or 0.15 μm in at least one direction. In one embodiment, a self-supporting pellicle film of the HARM structure has a size of larger than 15 μm, 12 μm, 9 μm, 7 μm, 5 μm, 3 μm, 2.5 μm, 1.5 μm, 1 μm, 0.5 μm, 0.3 μm, or 0.15 μm in at least one direction, for 1 cm 2 Each may contain 10 or fewer defects, 5 or fewer defects, 3 or fewer defects, 1 or fewer defects, or 0 defects.

[0024] The inventors unexpectedly discovered that the method disclosed herein can reduce the number of defects present in the self-supporting pellicle film of the HARM structure compared to directly depositing the entire HARM structure only on a porous filter. The number of defects may be determined by using an optical microscope configuration such as the Olympus MX63L, which differs in that it uses a camera instead of an eyepiece. The following parameters may be used: Light source: Olympus BX3M LEDR LED light source for reflected light, Objective lens: 10x (Olympus MPLFLN20XBD plain fluorite objective lens) Working distance: 6.5mm Imaging device: DP28-CU microscope camera, Resolution: 0.68 μm / pixel Stage: Motorized XY stage, Image analysis software: Olympus Stream Motion and ImageJ 1.52a.

[0025] The frame containing the self-supporting pellicle film with a HARM structure is placed on the microscope's XY stage below the microscope's objective lens. Using microscope software, the stage is moved to a vertical position (Z-axis) where the surface of the self-supporting pellicle film with the HARM structure is at the focal point of the objective lens. The user then uses computer software to inspect the captured image of the surface. Defective areas are identified as darker areas because the microscope acquires images using light reflected from the surface of the sample. Therefore, areas with fewer pores or HARM structures appear darker because less light is reflected from those areas.

[0026] In one embodiment, the self-supporting pellicle film with a HARM structure exhibits transmittance differential values ​​of 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.35% or less, 0.33% or less, 0.30% or less, 0.25% or less, 0.20% or less, 0.15% or less, 0.10% or less, or 0.05% or less.

[0027] The deposition of the first portion of the HARM structure and the deposition of the second portion of the HARM structure may be continued until a predetermined or desired transmittance is achieved. During the deposition of the first portion of the HARM structure, a fairly thin film of the HARM structure may be deposited, or alternatively, a thicker film of the HARM structure may be deposited. The same applies to the step of depositing the second portion of the HARM structure on the self-supporting film of the HARM structure, i.e., a thick or thin deposition may be formed. Thus, the deposition of the first portion of the HARM structure may be continued until the transmittance of the film of the HARM structure is 1-99%. Furthermore, the deposition of the second portion of the HARM structure may be continued until the transmittance of the self-supporting pellicle film of the HARM structure reaches a predetermined or desired value.

[0028] In one embodiment, the deposition of the first portion of the HARM structure is sustained until the transmittance of the HARM structure film is 80-99%, 85-98%, 90-96%, or 92-94% of the energy of light incident perpendicularly on it per unit time when measured at a wavelength of 550 nm. In one embodiment, the deposition of the first portion of the HARM structure is sustained until the transmittance of the HARM structure film is 90-99%, 92-98%, or 94-96% of the energy of light incident perpendicularly on it per unit time when measured at a wavelength of 550 nm. The transmittance of the deposit formed on the porous filter may be measured in situ using a camera. Any suitable camera may be used. For example, a 10-bit, 1.6MP monochrome camera may be used. The final transmittance value may then be determined after transferring the HARM structure film to a frame.

[0029] In one embodiment, the deposition of the second portion of the HARM structure is sustained until the transmittance of the self-supporting pellicle film of the HARM structure reaches 50-95%, 55-93%, 60-87%, 65-86%, 70-85%, or 75-80% of the energy of light incident perpendicularly on it per unit time when measured at a wavelength of 550 nm. In one embodiment, the deposition of the second portion of the HARM structure is sustained until the transmittance of the self-supporting pellicle film of the HARM structure reaches 80-87%, 81-86%, or 82-85% of the energy of light incident perpendicularly on it per unit time when measured at a wavelength of 550 nm.

[0030] The transmittance or transparency of a film refers to its transparency in the thickness direction of the film or a part thereof. Therefore, for it to be "transparent," a sufficient portion of the light energy incident on the film or a part thereof will propagate through it in the thickness direction.

[0031] In one embodiment, the deposition of the first portion of the HARM structure is continued until the thickness of the HARM structure film is 3-50 nm, 5-45 nm, 7-40 nm, 10-35 nm, 15-30 nm, or 20-25 nm. In one embodiment, the deposition of the second portion of the HARM structure is continued until the thickness of the HARM structure self-supporting pellicle film is 75-400 nm, 76-350 nm, 77-300 nm, 78-250 nm, 79-200 nm, 80-160 nm, 81-140 nm, 82-120 nm, 83-110 nm, 84-100 nm, or 85-90 nm. The film thickness may be measured by an atomic force microscope (AFM) or a contact profiler such as an optical profiler.

[0032] In one embodiment, the method includes the step of depositing a first portion of the HARM structure until the thickness of the HARM structure film is 99-75% or 95-85% of the total thickness of the self-supporting pellicle film of the HARM structure to be formed.

[0033] In one embodiment, the formed self-supporting pellicle film with a HARM structure is set to have a predetermined transmittance value, and the deposition of the first portion of the HARM structure is continued until the HARM structure film exhibits a predetermined transmittance value of 75-15%, 65-35%, or 55-35%. In one embodiment, the formed self-supporting pellicle film with a HARM structure is set to have a predetermined transmittance value, and the deposition of the first portion of the HARM structure is continued until the HARM structure film exhibits a predetermined transmittance value of 75-65%, 65-55%, 55-35%, or 35-15%.

[0034] In step a), the film of the HARM structure formed on the porous filter is transferred to a frame in step b) to form a self-supporting film of the HARM structure. The frame can support the self-supporting film of the HARM structure, or the self-supporting pellicle film of the HARM structure, at its outer edges in a later step, so that an unsupported, standalone region of the self-supporting (pellicle) film of the HARM structure is formed. The support positions may be located anywhere in the structure, as long as they provide sufficient support to the self-supporting (pellicle) film of the HARM structure. For example, the support positions may be on the sides of the self-supporting (pellicle) film of the HARM structure, in the area near the corners, or adjacent to each other along the sides. Any wider area containing multiple support points will also be covered by this embodiment; for example, if the frame has a continuous circular shape, the self-supporting region will be within the circle. The frame may further have any other extended, continuous shape. In one embodiment, the frame is formed as a circle, square, triangle, rectangle, oval, or polygon.

[0035] In one embodiment, the frame is made of a polymer, quartz, titanium, graphite, silicon, silicon carbide, silicon nitrate, polysilicon, transition metal, or an alloy of transition metals.

[0036] In one embodiment, the method further includes the step of depositing at least one further portion of the HARM structure or other nanomaterial onto a self-supporting pellicle film of the HARM structure. In one embodiment, the method further includes the step of depositing at least one further portion of the HARM structure or other nanomaterial onto a self-supporting pellicle film of the HARM structure from the gas phase. The term "other nanomaterials" may refer to boron nitride nanotubes (BNNTs), nanoplattelets, nanoribbons, nanowires, and nanofibers. Examples of nanoplattelets may include graphene nanoplattelets, boronphene nanoplatelets, and boron carbide nanoplattelets. Examples of nanoribbons may include graphene nanoribbons and graphite nanoribbons. Examples of nanowires may include tungsten nanowires, copper nanowires, aluminum nanowires, nickel nanowires, or silver nanowires. Examples of nanofibers may include carbon nanofibers and silicon carbide nanofibers. In one embodiment, the method further includes the step of depositing a polymer onto a self-supporting pellicle film of the HARM structure. Further practical benefits are obtained by further depositing portions of the same or different nanomaterials onto the self-supporting pellicle film of the HARM structure, which makes it possible to form a pellicle film having a hybrid material structure.

[0037] In one embodiment, the method further includes the step of depositing a third portion of the HARM structure onto a self-supporting pellicle film of the HARM structure. In one embodiment, the method further includes the step of depositing a third portion of the HARM structure onto a self-supporting pellicle film of the HARM structure from the gas phase.

[0038] In one embodiment, the method further includes the step of retransferring a formed, self-supporting pellicle film of HARM structure, attached to a frame, from the frame to a second frame, the size of which the second frame is smaller than the size of the first frame, and the second frame is pressed through the self-supporting pellicle film of HARM structure attached to the frame in order to stretch the self-supporting pellicle film of HARM structure. Thus, as a result of the retransfer, the self-supporting pellicle film of HARM structure is stretched, thereby making the self-supporting pellicle film flatter, often by improving the mechanical properties of the self-supporting pellicle film and reducing any "wrinkles" that may be present.

[0039] The material of the second frame may be different from the material of the first frame. The step of re-transferring the self-supporting pellicle film of the HARM structure from the first frame to the second frame provides further benefits, such as enabling post-treatment methods that may otherwise be harmful to the other frame materials, for example, in high-temperature or corrosive environments.

[0040] The methods disclosed herein offer further advantages in realizing self-supporting pellicle films containing a HARM structure with a smooth surface and a reduced number of defects. Since the number of defects in the self-supporting pellicle film can be reduced, its mechanical properties are improved. Furthermore, the ability of the self-supporting pellicle film for particle filtration can be enhanced.

[0041] Examples Next, we will provide a detailed reference to the described embodiments, which are shown in the attached drawings.

[0042] The following description discloses several examples in such detail that a person skilled in the art can form a self-supporting pellicle film containing a HARM structure according to this disclosure. Not all steps of the examples are discussed in detail, as many of them will be obvious to a person skilled in the art according to this specification.

[0043] For clarity, in the case of repeating components, the item numbers will be maintained in the following exemplary examples.

[0044] Figure 1 shows a method for forming a self-supporting pellicle film containing a HARM structure according to one embodiment. In the embodiment of Figure 1, in order to form a film of the HARM structure on a porous filter, first a first portion of the HARM structure is deposited onto the porous filter from, for example, the gas phase (number 1 in Figure 1).

[0045] To form a self-supporting film with a HARM structure attached to the frame, the HARM structure film is transferred from the porous filter to the frame (Figures 1-2 to 1-4).

[0046] To form a self-supporting film of the HARM structure attached to the frame, following the step of transferring the HARM structure film onto the frame, a second portion of the HARM structure is deposited onto the self-supporting film of the HARM structure attached to the frame, for example from the gas phase, to form a self-supporting pellicle film of the HARM structure attached to the frame (numbers 5-6 in Figure 1).

[0047] In the embodiment shown in Figure 1, a further step is indicated in which the formed self-supporting pellicle film of the HARM structure, which has been attached to the frame, is re-transferred from the frame to a second frame, the size of which the second frame is smaller than the size of the first frame, and the second frame is pressed through the self-supporting pellicle film of the HARM structure attached to the frame in order to stretch the self-supporting pellicle film of the HARM structure (number 7 in Figure 1).

[0048] Figure 3 shows an image of defects on the surface of a pellicle film that may form. The image was taken with an Olympus MX63L microscope. Arrows indicate the size of the defects in micrometers. These defects are indentations and areas with less carbon nanotube material.

[0049] Figure 4 illustrates how protruding defects present within the porous filter are transferred to the pellicle film formed on the porous filter by depositing a HARM structure onto the porous filter. The defects themselves represent indentations containing less HARM structure material.

[0050] "Example 1" Production of self-supporting pellicle film In this example, the different self-supporting pellicle films attached to the frame were produced using the following materials. [Table 1]

[0051] First, carbon nanotubes were synthesized in an aerosol laminar flow (floating catalyst) reactor using carbon monoxide and ferrocene as the carbon source and catalyst precursor, respectively. To form a carbon nanotube film on a porous filter, the first portion of the formed carbon nanotubes was deposited onto the porous filter from the gas phase at a total gas flow rate of 60 l / min (maximum gas velocity of 0.13 m / s). The gas temperature was approximately 60°C. The deposition of the first portion of the carbon nanotubes was continued until the transmittance of the carbon nanotube film reached 95% of the energy of light incident perpendicularly on it per unit time, as measured at a wavelength of 550 nm. The thickness of the formed carbon nanotube film ranged from 15 to 30 nm.

[0052] Next, to form a self-supporting film of carbon nanotubes attached to the frame, the formed carbon nanotube film was transferred from the porous filter to the frame. The frame had a rectangular shape with an opening in the center.

[0053] Next, to form a self-supporting pellicle film of carbon nanotubes attached to the frame, a second portion of carbon nanotubes was deposited from the gas phase onto the self-supporting film of carbon nanotubes attached to the frame. The deposition of the second portion of carbon nanotubes was continued until the transmittance of the self-supporting pellicle film of carbon nanotubes reached 87% of the energy of light incident perpendicularly on it per unit time, as measured at a wavelength of 550 nm. The thickness of the formed pellicle film was 70 nm.

[0054] Furthermore, comparative examples were created by producing similar self-supporting pellicle films using a different method, but the second portion of the carbon nanotubes was deposited from the gas phase onto a porous filter, which had an already formed film of carbon nanotubes on the porous filter.

[0055] To evaluate the heterogeneity of the different pellicle films formed, transmittance was measured as described herein. Based on the measurement results, the transmittance difference value was calculated using the following method. Transmittance difference (%) = Maximum transmittance (%) - Minimum transmittance (%).

[0056] The results can be seen in Table 1 below. [Table 2]

[0057] As can be seen from Table 1 above, the self-supporting pellicle film of carbon nanotubes has a transmittance difference of 0.32%.

[0058] Furthermore, the number of defects was measured as described herein. To obtain these measurement results, the following self-supporting pellicle films, attached to the frame, were produced using the following materials. [Table 3]

[0059] The results can be seen in Table 2 below. [Table 4]

[0060] As can be seen from Table 2 above, the number of defects per square centimeter in the self-supporting pellicle film of carbon nanotubes is significantly less than in the comparative examples.

[0061] As technology advances, it will be apparent to those skilled in the art that basic concepts can be implemented in various ways. Therefore, the examples are not limited to those described above, but may instead vary within the scope of the claims.

[0062] The embodiments described herein may be used in any combination of each other. Some of the embodiments may be combined integrally to form further embodiments. Methods or uses for forming a self-supporting pellicle film having a HARM structure, or a self-supporting pellicle film having a HARM structure attached to a frame, as 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. The embodiments are not limited to solving any or all of the problems listed, or having any or all of the benefits and advantages listed. It will be further understood that a reference to an item “one” refers to one or more of those items. The term “equipped with” is used herein to include the following feature or action without prejudice to the presence of one or more further features or actions.

Claims

1. A self-supporting pellicle film having a high aspect ratio molecular structure (HARM structure) attached to a frame, wherein the self-supporting pellicle film with the HARM structure exhibits a transmittance difference value of 1% or less when calculated using the following formula: Transmittance difference value (%) = Maximum transmittance (%) - Minimum transmittance (%) The maximum transmittance is the maximum value of the transmittance measured at a wavelength of 550 nm for the self-supporting pellicle film of the HARM structure. The minimum transmittance is the minimum transmittance measured at a wavelength of 550 nm for the self-supporting pellicle film of the HARM structure. The self-supporting pellicle film of the HARM structure is 1 cm ２ A self-supporting pellicle film, wherein each pellicle contains 10 or fewer defects, and each defect has a size greater than 15 μm in at least one direction.

2. The self-supporting pellicle film according to claim 1, wherein the self-supporting pellicle film having a HARM structure exhibits a transmittance difference value of 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.35% or less, 0.33% or less, 0.30% or less, 0.25% or less, 0.20% or less, 0.15% or less, 0.10% or less, or 0.05% or less.

3. The self-supporting pellicle film with HARM structure is 1 cm ２ The self-supporting pellicle film according to claim 1, wherein each contains 10 or fewer defects, 5 or fewer defects, 3 or fewer defects, 1 or fewer defects, or 0 defects.

4. The self-supporting pellicle film according to claim 1, wherein the thickness of the self-supporting pellicle film is 75-400 nm, 76-350 nm, 77-300 nm, 78-250 nm, 79-200 nm, 80-160 nm, 81-140 nm, 82-120 nm, 83-110 nm, 84-100 nm, or 85-90 nm.

5. The self-supporting pellicle film according to claim 1, wherein the self-supporting pellicle film is a pellicle film such as an extreme ultraviolet film for extreme ultraviolet lithography, an extreme ultraviolet debris filter, or a pellicle film for an X-ray window.

6. The self-supporting pellicle film according to claim 1, wherein the frame is made of a polymer, quartz, titanium, graphite, silicon, silicon carbide, silicon nitrate, polysilicon, a transition metal, or an alloy of a transition metal.

7. The self-supporting pellicle film according to claim 1, wherein the HARM structure is a carbon nanostructure.

8. Use of the self-supporting pellicle film according to claim 1 as an extreme ultraviolet film, as an extreme ultraviolet debris filter, or as a pellicle film for an X-ray window in extreme ultraviolet lithography.

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