Free-standing pellicle film with HARM structure

Abstract

A method for forming a free-standing pellicle film having a high aspect ratio molecular structure (HARM structure) is disclosed, the method including the steps of a) depositing a first portion of the HARM structure onto 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 free-standing film of the HARM structure attached to the frame, and c) depositing a second portion of the HARM structure onto the free-standing film of the HARM structure attached to the frame to form a free-standing pellicle film of the HARM structure attached to the frame.

Description

[Technical field]

[0001] The present disclosure relates to a method for forming a free-standing pellicle film having a high aspect ratio molecular structure (HARM structure). The present disclosure further relates to a free-standing pellicle film having a high aspect ratio molecular structure (HARM structure) attached to a frame. The present disclosure further relates to uses of the free-standing pellicle film. [Background technology]

[0002] Extreme ultraviolet lithography (EUV or EUVL) is an optical lithography technique using extreme ultraviolet wavelength range. EUV pellicle films are used to protect photomasks from defects, improve accuracy, shorten processing, and increase on-wafer production efficiency. However, defects in printing remain a major constraint to EUV lithography acceptance. Hence, sophisticated particle filters such as EUV pellicle films are needed. Summary of the Invention [Means for solving the problem]

[0003] A method for forming a free-standing pellicle film is disclosed. The method for forming a free-standing pellicle film having a high aspect ratio molecular structure (HARM structure) includes: a) depositing a first portion of a HARM structure onto 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 free-standing film of the HARM structure attached to the frame; and c) depositing a second portion of the HARM structure onto the free-standing film of the HARM structure attached to the frame to form a free-standing pellicle film of the HARM structure attached to the frame.

[0004] Further disclosed is a free-standing pellicle film having a high aspect ratio molecular structure (HARM structure) attached to a frame, the free-standing pellicle film having the HARM structure exhibiting a transmittance differential value of 1% or less when calculated according to the following formula: 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 a free-standing pellicle film with a HARM structure. The minimum transmittance is the minimum transmittance measured at a wavelength of 550 nm for a free-standing pellicle film of the HARM structure.

[0005] Further disclosed is the use of the free-standing pellicle film as an extreme UV membrane in extreme UV lithography, as an extreme UV debris filter, or as a pellicle film for an X-ray window.

[0006] The accompanying drawings, which are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification, illustrate embodiments. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 illustrates a method for forming a free-standing pellicle film of a HARM structure, according to one embodiment. [Diagram 2] FIG. 2 is a diagram showing a configuration of a light measurement device for measuring transmittance. [Diagram 3] FIG. [Figure 4] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present disclosure relates to a method for forming a free-standing pellicle film having a high aspect ratio molecular structure (HARM structure), the method comprising: a) depositing a first portion of a HARM structure onto 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 free-standing film of the HARM structure attached to the frame; and c) depositing a second portion of the HARM structure onto the free-standing film of the HARM structure attached to the frame to form a free-standing pellicle film of the HARM structure attached to the frame.

[0009] In one embodiment, the deposition of the first portion of the HARM structure and / or the second portion of the HARM structure is deposited from a vapor phase. In one embodiment, step a) is performed by depositing the first portion of the HARM structure onto a porous filter from a vapor phase to form a film of the HARM structure on the porous filter. In one embodiment, step c) is performed by depositing the second portion of the HARM structure from a vapor phase onto a free-standing film of the HARM structure attached to a frame to form a free-standing pellicle film of the HARM structure attached to the frame.

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

[0011] Porous filters usually have a surface that is neither smooth nor defect-free, as most surfaces do, but may also contain multiple defects in the form of small holes or bumps, as well as areas of high and low porosity. These porous filter defects may further affect the homogeneity of the film deposited on the porous filter. These defects may reduce the mechanical properties of the pellicle film and weaken its particle filtration capabilities, for example in particle filtration or EUV pellicle applications.

[0012] In order to reduce non-uniformity of the deposited film, efforts have usually been made to obtain a filter with as smooth and defect-free surface as possible for deposition. However, the inventors have unexpectedly found that first depositing a portion of the HARM structure on a porous filter and then depositing another portion of the HARM structure directly on the free-standing film of the HARM structure after transferring the formed film of the HARM structure to a frame can effectively reduce defects in the resulting free-standing pellicle film of the HARM structure. Without being limited to any particular theory as to why a highly smooth free-standing 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 on a free-standing film of the HARM structure, a thinner portion of the free-standing film of the HARM structure can pass a larger portion of the gas with the HARM structure than a thicker portion. This can result in a larger amount of the HARM structure being deposited on or within possible defects of the free-standing film of the HARM structure than on the remaining portion of the film.

[0013] The term "defects", unless otherwise stated, shall be understood herein as micropores, thinner areas, dents, holes, bumps, or areas of high and low porosity in the pellicle film.

[0014] The present disclosure further relates to a free-standing pellicle film having a high aspect ratio molecular structure (HARM structure) attached to a frame, the free-standing pellicle film having the HARM structure exhibiting a transmittance differential value of 1% or less 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 a free-standing pellicle film with a HARM structure. The minimum transmittance is the minimum transmittance measured at a wavelength of 550 nm for a free-standing pellicle film of the HARM structure.

[0015] The transmittance can be measured by using the light measurement device configuration presented in Figure 2 according to the following: The device is calibrated to 100%T and 0%T. The frame with the pellicle attached is placed on the 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 about 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 2 ), one %T measurement point is taken. The maximum and minimum measured values ​​are used to calculate the transmittance difference value (%).

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

[0018] The expression "HARM structure" or "HARMS", unless otherwise stated, should be understood herein to refer to "nanostructures", i.e. structures having one or more characteristic dimensions on the nanometer scale, i.e. about 100 nanometers or less. "High aspect ratio" refers to the dimensions of a conductive structure in two perpendicular directions being on the order of magnitude significantly different. For example, a nanostructure may have a length tens or hundreds of times higher than its thickness and / or width. In a film of a HARM structure, a large number of said nanostructures are interconnected with each other to form a network of interconnected molecules. Considered on a macroscopic scale, a HARMS network forms a solid monolithic material in which the individual molecular structures are disoriented or unoriented, i.e. substantially randomly oriented or oriented. Various types of HARM structure networks can be produced in the form of thin transparent layers with reasonable resistivities. 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 comprises a carbon nanotube, a carbon nanobud, a carbon nanoribbon, or any combination thereof. In one embodiment, the carbon nanostructure comprises a carbon nanotube and / or a carbon nanobud. Carbon nanobuds, or carbon nanobud molecules as they may further be called, have fullerene or fullerene-like molecules 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 can be first generated in the gas phase in a reactor and deposited from the gas phase onto the porous filter or onto a free-standing film of the HARM structure, respectively. Deposition may be so performed by, for example, allowing a gas flow, such as a carrier gas carrying 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. Alternatively, the carrier gas may be passed 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 with the HARM structure through a porous filter or a free-standing film of the HARM structure at a total gas flow rate of 5-500 l / min. The gas flow rate can be, for example, 5-30 l / min, or alternatively 30-90 l / min, 40-80 l / min, or 50-70 l / min, or alternatively 90-500 l / min, 100-450 l / min, or 150-400 l / min. The higher the flow rate, the higher the throughput of the gas stream through the porous filter of the free-standing film of the HARM structure, thereby affecting the costs involved in the process.

[0022] In one embodiment, a free-standing pellicle film having a HARM structure is formed that exhibits a transmittance differential value of 1% or less 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 a free-standing pellicle film with a HARM structure. The minimum transmittance is the minimum transmittance measured at a wavelength of 550 nm for a free-standing pellicle film of the HARM structure.

[0023] In one embodiment, the free-standing pellicle film of the HARM structure is 1 cm 2 In one embodiment, the free-standing pellicle film of the HARM structure has a size of 1 cm or less, 10 or less, 5 or less, 3 or less, 1 or less, or 0 defects. 2 The number of defects may be greater than 15 μm, greater than 12 μm, greater than 9 μm, greater than 7 μm, greater than 5 μm, greater than 3 μm, greater than 2.5 μm, greater than 1.5 μm, greater than 1 μm, greater than 0.5 μm, greater than 0.3 μm, or greater than 0.15 μm in at least one direction. In one embodiment, the free-standing pellicle film of the HARM structure includes a 1 cm2 defect having a size of greater than 15 μm, greater than 12 μm, greater than 9 μm, greater than 7 μm, greater than 5 μm, greater than 3 μm, greater than 2.5 μm, greater than 1.5 μm, greater than 1 μm, greater than 0.5 μm, greater than 0.3 μm, or greater than 0.15 μm in at least one direction. 2 Contains 10 or less, 5 or less, 3 or less, 1 or less, or 0 defects per unit.

[0024] What the inventors unexpectedly found was that the method disclosed herein can reduce the number of defects present in a free-standing pellicle film of a HARM structure, compared to depositing all of the HARM structure directly onto a porous filter only. The number of defects may be determined by using an optical microscope setup such as an Olympus MX63L, with the difference being that a camera is used 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: 0.68μm / pixel, Stage: Motorized XY stage, Image analysis software: Olympus stream motion and ImageJ 1.52a.

[0025] The frame containing the HARM structured free-standing pellicle film is placed on the microscope XY stage below the microscope objective. Using the microscope software, the stage is moved vertically (Z axis) to a position where the surface of the HARM structured free-standing pellicle film is at the focus of the objective. The user then uses the 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 sample's surface. Thus, areas with fewer holes or HARM structures will appear darker because less light is reflected from those areas.

[0026] In one embodiment, a freestanding pellicle film having a HARM structure exhibits a transmittance differential 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.

[0027] The deposition of the first part of the HARM structure and the deposition of the second part of the HARM structure may be continued until a predetermined or desired transmittance is reached. During the deposition of the first part 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 part of the HARM structure on the free-standing film of the HARM structure, i.e. a thick or thin deposition may be formed. Thus, the deposition of the first part of the HARM structure may be continued until the transmittance of the film of the HARM structure is between 1 and 99%. Furthermore, the deposition of the second part of the HARM structure may be continued until the transmittance of the free-standing 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 continued until the transmittance of the film of the HARM structure is 80-99%, 85-98%, 90-96%, or 92-94% of the energy of light per unit time perpendicularly incident thereon when measured at a wavelength of 550 nm. In one embodiment, the deposition of the first portion of the HARM structure is continued until the transmittance of the film of the HARM structure is 90-99%, 92-98%, or 94-96% of the energy of light per unit time perpendicularly incident thereon 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. An example may be as small as a 10-bit, 1.6 MP monochrome camera. The final transmittance value may then be determined after transferring the film of the HARM structure to a frame.

[0029] In one embodiment, deposition of the second portion of the HARM structure is continued until the transmittance of the free-standing pellicle film of the HARM structure is 50-95%, 55-93%, 60-87%, 65-86%, 70-85%, or 75-80% of the energy of light incident normally thereon per unit time as measured at a wavelength of 550 nm. In one embodiment, deposition of the second portion of the HARM structure is continued until the transmittance of the free-standing pellicle film of the HARM structure is 80-87%, 81-86%, or 82-85% of the energy of light incident normally thereon per unit time as measured at a wavelength of 550 nm.

[0030] The transmittance or transparency of a film refers to the transparency through the thickness of the film or a portion thereof such that, to be "transparent", a sufficient portion of the light energy incident on the film or a portion thereof will propagate through it through the thickness.

[0031] In one embodiment, deposition of the first portion of the HARM structure is continued until the thickness of the HARM structure film is between 3-50 nm, 5-45 nm, 7-40 nm, 10-35 nm, 15-30 nm, or 20-25 nm. In one embodiment, deposition of the second portion of the HARM structure is continued until the thickness of the free-standing pellicle film of the HARM structure is between 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 thickness of the film may be measured by atomic force microscopy (AFM) or a contact profilometer such as an optical profilometer.

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

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

[0034] The film of the HARM structure formed on the porous filter in step a) is transferred to a frame in step b) to form a free-standing film of the HARM structure. The frame can support the free-standing film of the HARM structure or the free-standing pellicle film of the HARM structure at its outer edges at a later stage so that an unsupported stand-alone area of ​​the free-standing (pellicle) film of the HARM structure is formed. The support locations may be located anywhere in the structure as long as they provide sufficient support to the free-standing (pellicle) film of the HARM structure. For example, the support locations may be on the side of the free-standing (pellicle) film of the HARM structure, in an area near a corner, or next to each other along the side. Any wider area including multiple support points will also be covered by this embodiment, for example, if the frame has an uninterrupted circular shape, the free-standing area is in a circle. The frame may also have any other extended uninterrupted shape. In one embodiment, the frame is shaped as a circle, a square, a triangle, a rectangle, an oval, or a polygon.

[0035] In one embodiment, 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.

[0036] In one embodiment, the method further comprises depositing at least one additional portion of the HARM structure or other nanomaterial onto the free-standing pellicle film of the HARM structure. In one embodiment, the method further comprises depositing at least one additional portion of the HARM structure or other nanomaterial onto the free-standing pellicle film of the HARM structure from the vapor phase. The term "other nanomaterial" may refer to boron nitride nanotubes (BNNTs), nanoplatelets, nanoribbons, nanowires, and nanofibers. Examples of nanoplatelets may include graphene nanoplatelets, boronphene nanoplatelets, and boron carbide nanoplatelets. 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 comprises depositing a polymer onto the free-standing pellicle film of the HARM structure. Further deposition of portions of the same or different nanomaterials onto the free-standing pellicle film of the HARM structure provides an additional benefit of allowing the formation of a pellicle film having a hybrid material structure.

[0037] In one embodiment, the method further comprises depositing a third portion of the HARM structure onto the free-standing pellicle film of the HARM structure.In one embodiment, the method further comprises depositing a third portion of the HARM structure onto the free-standing pellicle film of the HARM structure from a vapor phase.

[0038] In one embodiment, the method further includes a step of retransferring the formed HARM structured free-standing pellicle film attached to the frame from the frame to a second frame, the size of the second frame being smaller than the size of the frame, and the second frame being pressed through the HARM structured free-standing pellicle film attached to the frame to stretch the HARM structured free-standing pellicle film. Thus, as a result of the retransfer, the HARM structured free-standing pellicle film is stretched, which can often further flatten the free-standing pellicle film by improving the mechanical properties of the free-standing pellicle film and reducing "wrinkles" that may be present.

[0039] The material of the second frame may be different from the material of the frame. The step of retransferring the free-standing pellicle film of the HARM structure from the frame to the second frame provides the additional benefit of enabling post-processing methods that may be performed, for example, at high temperatures or in a corrosive environment, that would otherwise be detrimental to the other frame materials.

[0040] The methods disclosed herein provide the additional benefit of providing free-standing pellicle films containing HARM structures with smooth surfaces and reduced numbers of defects. Because the amount of defects in the free-standing pellicle films can be reduced, their mechanical properties are improved. Furthermore, the ability of the free-standing pellicle films for particle filtration can be enhanced.

[0041] Real-life examples Reference will now be made in detail to the described embodiments, examples of which are illustrated in the accompanying drawings.

[0042] The following description discloses several examples in sufficient detail to enable one of ordinary skill in the art to form a free-standing pellicle film that includes a HARM structure according to the present disclosure. Not every step of the examples is discussed in detail, as many of the steps will be apparent to one of ordinary skill in the art based on this specification.

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

[0044] Figure 1 illustrates a method for forming a free-standing pellicle film including a HARM structure, according to one embodiment. In the embodiment of Figure 1, to form a film of a HARM structure on a porous filter, first a first portion of the HARM structure is deposited, for example from a vapor phase, onto the porous filter (number 1 in Figure 1).

[0045] To form a free-standing film of the HARM structure attached to the frame, the film of the HARM structure is transferred from the porous filter to the frame (2-4 in FIG. 1).

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

[0047] The embodiment of FIG. 1 further shows a step of retransferring the formed, free-standing pellicle film of the HARM structure attached to the frame from the frame to a second frame, the size of the second frame being smaller than the size of the frame, and the second frame being pressed through the free-standing pellicle film of the HARM structure attached to the frame to stretch the free-standing pellicle film of the HARM structure (number 7 in FIG. 1).

[0048] Figure 3 shows images of defects on the surface of a pellicle film that may have formed. The images are taken with an Olympus MX63L microscope. The arrows indicate the size of the defects in micrometers. These defects are dents, and areas with less carbon nanotube material.

[0049] Figure 4 shows how a protruding defect present in a porous filter is transferred to the pellicle film formed on the porous filter by depositing the HARM structure onto the porous filter. The defect manifests itself as an indentation that contains less HARM structure material.

[0050] "Example 1" Generation of free-standing pellicle films In this example, different free-standing pellicle films attached to a frame were produced by 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 carbon source and catalyst precursor, respectively. To form a carbon nanotube film on a porous filter, the first part of the formed carbon nanotubes was deposited on the porous filter from the gas phase at a total gas flow rate of 60 l / min (gas velocity up to 0.13 m / s). The temperature of the gas was about 60 °C. The deposition of the first part of the carbon nanotubes was continued until the transmittance of the carbon nanotube film was 95% of the light energy per unit time perpendicularly incident on it, measured at a wavelength of 550 nm. The thickness of the formed carbon nanotube film ranged from 15 to 30 nm.

[0052] The resulting carbon nanotube film was then transferred from the porous filter to a frame to form a free-standing film of carbon nanotubes that was attached to the frame. The frame had a rectangular shape with an opening in the center.

[0053] A second portion of carbon nanotubes was then deposited from the vapor phase onto the free-standing carbon nanotube film attached to the frame to form a free-standing pellicle film of carbon nanotubes attached to the frame. The deposition of the second portion of carbon nanotubes was continued until the transmittance of the free-standing carbon nanotube pellicle film was 87% of the light energy per unit time normally incident thereon, measured at a wavelength of 550 nm. The thickness of the pellicle film formed was 70 nm.

[0054] Additionally, a comparative example was made by creating a similar free-standing pellicle film in a different way, but a second portion of carbon nanotubes was deposited from the vapor phase onto the porous filter with an already formed film of carbon nanotubes on the porous filter.

[0055] To evaluate the inhomogeneity of the different pellicle films formed, the transmittance was measured as described herein. Based on the measurement results, the transmittance difference value was calculated in the following manner: Transmittance difference value (%) = maximum transmittance (%) - minimum transmittance (%).

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

[0057] It can be seen from Table 1 above that the free-standing pellicle film of carbon nanotubes has a transmittance differential value of 0.32%.

[0058] In addition, the number of defects was measured as described herein. To obtain these measurements, the following free-standing pellicle films attached to a frame were produced using the following materials: [Table 3]

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

[0060] It can be seen from Table 2 above that the freestanding carbon nanotube pellicle films have significantly fewer defects per square centimeter than the comparative examples.

[0061] It is obvious to those skilled in the art that with the advancement of technology, the basic concept can be implemented in various ways. Therefore, the embodiments are not limited to the examples described above, but may vary within the scope of the claims.

[0062] The embodiments described hereinbefore may be used in any combination with each other. Some of the embodiments may be combined together to form further embodiments. As disclosed herein, a method for forming a free-standing pellicle film having a HARM structure or a free-standing pellicle film having a HARM structure attached to a frame or a use may include at least one of the embodiments described hereinbefore. It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the problems listed or those that have any or all of the benefits and advantages listed. It will be further understood that a reference to "an" item refers to one or more of those items. The term "comprising" is used herein to contemplate including the feature(s) or act(s) that follows it without excluding the presence of one or more additional features or acts.

Claims

1. 1. A method for forming a free-standing pellicle film having a high aspect ratio molecular structure (HARM structure), comprising: a) depositing a first portion of a HARM-structure onto a porous filter to form a film of the HARM-structure on said porous filter; b) transferring said film of HARM-structures from said porous filter to a frame to form a free-standing film of HARM-structures attached to said frame; and c) depositing a second portion of a HARM-structure onto said free-standing film of a HARM-structure attached to said frame to form a free-standing pellicle film of a HARM-structure attached to said frame.

2. A free-standing pellicle film of the HARM structure is formed that exhibits a transmittance differential value of less than 1% when the following formula is calculated: Transmittance difference value (%) = maximum transmittance (%) - minimum transmittance (%), Maximum transmittance is the maximum value of transmittance measured at a wavelength of 550 nm for said free-standing pellicle film in a HARM structure; 2. The method of claim 1, wherein the minimum transmittance is the minimum transmittance measured at a wavelength of 550 nm for the free-standing pellicle film in a HARM structure.

3. 3. The method of claim 2, wherein the free-standing pellicle film of the HARM structure exhibits a transmittance differential 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.

4. The free-standing pellicle film of the HARM structure is 1 cm ２ The method of claim 1 , wherein the number of defects per pixel is 10 or less, 5 or less, 3 or less, 1 or less, or zero defects per pixel.

5. 5. A method according to any one of claims 1 to 4, wherein the deposition of the first part of the HARM-structure and / or the second part of the HARM-structure is deposited from the gas phase.

6. 6. The method of any one of claims 1 to 5, wherein the deposition of the first portion of a HARM-structure is continued until the transmittance of the film of a HARM-structure is 80-99%, 85-98%, 90-96%, or 92-94% of the energy of light per unit time normally incident thereon when measured at a wavelength of 550 nm.

7. 7. The method of any one of claims 1 to 6, wherein the deposition of the second portion of a HARM-structure is continued until the transmittance of the free-standing pellicle film of a HARM-structure is 50-95%, 55-93%, 60-87%, 65-86%, 70-85%, or 75-80% of the energy of light per unit time normally incident thereon when measured at a wavelength of 550 nm.

8. 8. The method of any one of claims 1 to 7, wherein the deposition of the first portion of a HARM-structure is continued until the thickness of the film of a HARM-structure is between 3-50 nm, 5-45 nm, 7-40 nm, 10-35 nm, 15-30 nm, or 20-25 nm.

9. 9. The method of any one of claims 1 to 8, wherein the deposition of the second portion of a HARM-structure is continued until the thickness of the free-standing pellicle film of a HARM-structure 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.

10. 10. The method of claim 1, wherein the formed free-standing pellicle film of a HARM-structure is set to have a predetermined transmittance value, and the deposition of the first portion of a HARM-structure is continued until the film of a HARM-structure exhibits a transmittance of 75-15%, 65-35%, or 55-35%, said predetermined transmittance value.

11. 11. The method of 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.

12. 12. The method of claim 1, further comprising depositing at least one further portion of HARM-structures or other nanomaterial onto the free-standing pellicle film.

13. 13. The method according to any one of claims 1 to 12, wherein said HARM-structures are carbon nanostructures.

14. 14. The method of claim 1, further comprising the step of retransferring the formed, free-standing HARM-structured pellicle film attached to the frame from the frame to a second frame, the size of the second frame being smaller than the size of the frame, and the second frame being pressed through the free-standing HARM-structured pellicle film attached to the frame to stretch the free-standing HARM-structured pellicle film.

15. 15. The method of any one of claims 1 to 14, wherein the free-standing pellicle film is a pellicle film, such as an extreme ultraviolet membrane for extreme ultraviolet lithography, an extreme ultraviolet debris filter, or a pellicle film for an X-ray window.

16. A free-standing pellicle film having a high aspect ratio molecular structure (HARM structure) attached to a frame, said free-standing pellicle film having a HARM structure exhibits a transmittance differential value of 1% or less when the following formula is calculated: Transmittance difference value (%) = maximum transmittance (%) - minimum transmittance (%), Maximum transmittance is the maximum value of transmittance measured at a wavelength of 550 nm for said free-standing pellicle film in a HARM structure; A free-standing pellicle film, wherein the minimum transmittance is the minimum value of the transmittance measured at a wavelength of 550 nm for said free-standing pellicle film in a HARM structure.

17. 17. The free-standing pellicle film of claim 16, wherein the free-standing pellicle film of the HARM structure exhibits a transmittance differential 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.

18. The free-standing pellicle film of the HARM structure is 1 cm ２ 18. The free-standing pellicle film of claim 16 or 17, comprising 10 or less, 5 or less, 3 or less, 1 or less, or 0 defects per unit area.

19. The free-standing pellicle film according to any one of claims 16 to 18, wherein the free-standing pellicle film has a thickness of 75 to 400 nm, 76 to 350 nm, 77 to 300 nm, 78 to 250 nm, 79 to 200 nm, 80 to 160 nm, 81 to 140 nm, 82 to 120 nm, 83 to 110 nm, 84 to 100 nm, or 85 to 90 nm.

20. The free-standing pellicle film of any one of claims 16 to 19, wherein the free-standing pellicle film is a pellicle film, such as an extreme ultraviolet membrane, an extreme ultraviolet debris filter, or a pellicle film for an X-ray window for extreme ultraviolet lithography.

21. 21. The free-standing pellicle film of any one of claims 16 to 20, 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.

22. 22. The free-standing pellicle film of any one of claims 16 to 21, wherein the HARM structures are carbon nanostructures.

23. 23. Use of the free-standing pellicle film according to any one of claims 16 to 22 in extreme ultraviolet lithography as an extreme ultraviolet membrane, as an extreme ultraviolet debris filter, or as a pellicle film for an X-ray window.

Images