Pellicle film, pellicle, exposure plate, exposure apparatus, and method for manufacturing pellicle film

Abstract

To provide a pellicle film hard to decrease a film thickness even if exposed to hydrogen plasma, a pellicle, an exposure original plate, an exposure apparatus, and a production method of a pellicle film hard to decrease a film thickness even if exposed to hydrogen plasma.SOLUTION: A pellicle film includes a plurality of carbon nanotubes where a part of the carbon nanotubes forms a plurality of bundles. The diffraction peak ratio of the pellicle film is 1.3 or larger. The diffraction peak ratio expresses a ratio of a height of a specific second Gaussian function which is a constituent element of a specific second fitting function obtained by fitting a specific second plot curve to a height of a specific first Gaussian function which is a constituent element of a specific first fitting function obtained by fitting a specific first plot curve in a restricted visual field diffraction image obtained by observing a surface of the pellicle film by a transmission electron microscope.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This disclosure relates to a pellicle film, a pellicle, an exposure master plate, an exposure apparatus, and a method for manufacturing a pellicle film. [Background technology]

[0002] Miniaturization of semiconductor integrated circuits is being driven by photolithography. In recent years, with the increasing resolution of semiconductor integrated circuits, EUV (Extreme Ultraviolet) light has been used. Because EUV light has a short wavelength, it is easily absorbed by gases, liquids, and solids. Therefore, in exposure methods using EUV light, a photomask equipped with a reflective layer that reflects EUV light is used, and the photomask and optical system are installed in a vacuum chamber. Exposure using EUV light as the light used for exposure (hereinafter referred to as "exposure light") (hereinafter referred to as "EUV exposure") is performed in a vacuum atmosphere.

[0003] However, residual gases (e.g., moisture and organic matter) remain in the vacuum chamber, and irradiation with EUV light may cause carbon film deposition on the surfaces of mirrors and masks included in the optical system (hereinafter referred to as "contamination"). Contamination may lead to a decrease in throughput and a deterioration of transfer performance. As a countermeasure against contamination, instead of disassembling and cleaning the optical system, hydrogen gas is supplied into a vacuum chamber to clean the generated contamination in situ (for example, Patent Document 1).

[0004] A pellicle is attached to the photomask to prevent foreign matter such as dust from adhering to the surface of the photomask. The pellicle comprises a pellicle film and a pellicle frame that supports the pellicle film. Carbon nanotubes are known as a raw material for pellicle films that are transparent to EUV light (for example, Patent Document 1). The supergrowth method (hereinafter referred to as the "SG method") is known as a method for producing single-walled carbon nanotubes (for example, Patent Document 2).

[0005] Patent Document 1: Japanese Unexamined Patent Publication No. 2020-181212 Patent Document 2: International Publication No. 2006 / 011655 [Overview of the project] [Problems that the invention aims to solve]

[0006] As a measure against contamination, it is thought that the hydrogen gas supplied into the vacuum chamber will become hydrogen plasma upon irradiation with EUV light. Pellicle films made using carbon nanotubes produced by the SG method may be prone to film thinning when exposed to hydrogen plasma. Film thinning of the pellicle film due to hydrogen plasma is undesirable because it causes fluctuations in the transmittance of exposure light during exposure, leading to a deterioration of transfer performance.

[0007] This disclosure is made in light of the circumstances described above. One embodiment of this disclosure aims to solve the problem of providing a pellicle film, a pellicle, an exposure master, and an exposure apparatus that are less susceptible to film reduction even when exposed to hydrogen plasma. Another problem that other embodiments of this disclosure aim to solve is to provide a method for manufacturing a pellicle film that is less prone to film degradation even when exposed to hydrogen plasma. [Means for solving the problem]

[0008] The following embodiments are included as means for solving the above problems. <1> Contains multiple carbon nanotubes, A pellicle film in which the average value of the linearity parameter of the plurality of carbon nanotubes, represented by the following formula (1), is 0.10 or less. Equation (1): Linearity parameter = Standard deviation Sa of the width of a single carbon nanotube / Mean value Aa of the width (In the above formula (1), The standard deviation Sa and the mean value Aa are each calculated based on 11 measurements obtained by measuring the width of one carbon nanotube at 2 nm intervals along the longitudinal direction of one carbon nanotube. <2> The aforementioned plurality of carbon nanotubes form a bundle, The average value of the packing density parameters of the plurality of bundles, represented by the following formula (2), is 0.20 or less. <1> The pellicle membrane described above. Equation (2): Packing density parameter = Standard deviation Sb of the distance between the centers of multiple carbon nanotubes constituting one bundle / Mean value Ab of the distance between the centers (In the above formula (2), The distance between the center points is the length of the straight line connecting the center points in a 20 nm × 20 nm range transmission electron microscope image containing one bundle of the pellicle film obtained by cutting the pellicle film along the thickness direction of the pellicle film, after identifying the center point of each annular contour line of multiple carbon nanotubes in the transmission electron microscope image, such that multiple triangles satisfying predetermined conditions are formed. The aforementioned predetermined conditions include that the sides of the plurality of triangles do not intersect, that three center points are selected such that the sum of the lengths of the three sides of the triangles is minimized, and that the interior angle of the outermost triangle among the plurality of triangles is less than 120°. The standard deviation Sb and the mean Ab are each calculated based on a plurality of distances between center points that are less than or equal to a predetermined value. The predetermined value is obtained by multiplying the average value of the distances between the center points, from the shortest distance (1st) to the predetermined rank, by 1.6. The predetermined rank is indicated by the integer obtained by rounding the first decimal place of the number obtained by multiplying the total distance between the multiple center points by 0.8. <3> The average value of the packing density parameter is 0.15 or less. <2> The pellicle membrane described above. <4> It contains multiple carbon nanotubes forming a bundle, The diffraction peak ratio is 1.3 or higher. The diffraction peak ratio is the ratio of the height of the second Gaussian function, which is a component of the second fitting function obtained by fitting the second plot curve, to the height of the first Gaussian function, which is a component of the first fitting function obtained by fitting the first plot curve, in a restricted field of view diffraction image obtained by observing the surface of the pellicle film with a transmission electron microscope. The first plot curve is a profile of the diffraction intensity in a direction where the diffraction intensity derived from the bundle lattice of the bundle is weak, with respect to the scattering vector q. The second plot curve is a profile of the diffraction intensity in a direction where the diffraction intensity is strong, with respect to the scattering vector q. The first fitting function is a function represented by the sum of a function of the baseline common to the first plot curve and the second plot curve in the range where the scattering vector q is from q = 1.5 nm -1 to 4.0 nm -1 and a first Gaussian function whose peak center position of the first plot curve is in the range of q = 2.0 nm -1 to 3.0 nm -1 in the range. The second fitting function is a function represented by the sum of a function of the baseline and a second Gaussian function whose peak center position of the second plot curve is in the range of g = 2.0 nm -1 to 3.0 nm -1 in the range. The height of the first Gaussian function indicates the maximum value of the first Gaussian function in the range where the scattering vector q is from q = 2.0 nm -1 to 3.0 nm -1 in the range. The height of the second Gaussian function indicates the maximum value of the second Gaussian function in the range where the scattering vector q is from q = 2.0 nm -1 to 3.0 nm -1 in the range. The pellicle film according to any one of <1> to <3>. <5> includes a plurality of carbon nanotubes forming a bundle, The smoothness evaluation value is 0.070 (nm 2 / nm) or less, The aforementioned smoothness evaluation value represents the value obtained by dividing the area between the contour line of the carbon nanotube and the approximation curve of the contour line by the length of the approximation curve. The aforementioned contour line is obtained by tracing the wall portion of the CNT that appears as a dark line in a transmission electron microscope image of the surface of the pellicle film at a resolution of 100 pixels or more with a length of 5 nm. The aforementioned approximation curve is a curve drawn by quadratic spline interpolation of the coordinates of the contour line of the CNT, The outline and approximate curve of the carbon nanotube were extracted from 20 carbon nanotubes. The length of the outline is 20 nm for each carbon nanotube. The aforementioned <1> ~ <4> A pellicle membrane as described in any one of the following. <6> It contains multiple carbon nanotubes (CNTs) forming a bundle, The minimum value of the ratio of the intensity of the G band to the intensity of the D band (G / D) at seven locations within a predetermined bundle region in a cross-section of the pellicle film cut along the axial direction of the bundle is 0.80 or greater. The intensity of the D band and the intensity of the G band are measured by Raman imaging. The predetermined bundle region refers to a region within a bundle with a thickness of 10 nm or more and a spatial resolution of 20 nm or less in the 500 nm × 500 nm measurement area of ​​the cross-section. The intensity of the aforementioned D band is when the Raman shift is 1300 cm. -1 ~1400cm -1 This is the maximum value of Raman scattering intensity within the range, The intensity of the aforementioned G-band is when the Raman shift is 1550 cm. -1 ~1610cm -1 This is the maximum value of Raman scattering intensity within the range, The aforementioned <1> ~ <5> A pellicle membrane as described in any one of the following. <7> Pellicle frame and The pellicle frame supported <1> ~ <6> The pellicle membrane described in any one of the following and A pellicle equipped with this feature. <8> Photomask and The photomask attached to the <7> The pellicle described above An exposure master plate equipped with the following features. <9> An EUV light source that emits EUV light as exposure light, The aforementioned <8> The exposure plate described above, An optical system that guides the exposure light emitted from the EUV light source to the exposure plate, Equipped with, The exposure master plate is arranged such that the exposure light emitted from the EUV light source passes through the pellicle film and irradiates the photomask. <10> The aforementioned <1> ~ <6> A method for producing a pellicle film as described in any one of the following: A method for producing a pellicle film, comprising a coating step of applying a dispersion liquid containing multiple carbon nanotubes synthesized by direct injection pyrolysis synthesis to a substrate. <11> The process further includes a cleaning step of alkaline cleaning the coating film obtained in the coating step, <10> A method for producing a pellicle film as described above. [Effects of the Invention]

[0009] According to one embodiment of the present disclosure, it is possible to provide a pellicle film, a pellicle, an exposure master, and an exposure apparatus that are less susceptible to film reduction even when exposed to hydrogen plasma. According to other embodiments of this disclosure, a method for manufacturing a pellicle film that is less prone to film degradation even when exposed to hydrogen plasma can be provided. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a transmission electron microscope (TEM) image of a cross-section of an example of a single bundle. [Figure 2] Figure 2 is a TEM image in which the center points are plotted at the center of the annular contour line of each of the multiple CNTs in Figure 1. [Figure 3] Figure 3 shows multiple triangles obtained by connecting multiple center points in Figure 2 with straight lines. [Figure 4]Figure 4 shows a selected-field electron diffraction pattern of a cross-section of an example of a pellicle film. [Figure 5] Figure 5 is a graph plotting the diffraction intensity along the film plane direction and the film thickness direction against the scattering vector for a limited-field electron diffraction pattern (Figure 4) of a cross-section of an example of a pellicle film. [Figure 6] Figure 6 is a graph showing the difference in diffraction intensity between plotted curves A1 and A2 in Figure 5 and the approximation curve A3, respectively, with respect to the scattering vector. [Figure 7] Figure 7 is a graph showing the diffraction intensity obtained by fitting the difference curves A4 and A5 in Figure 6, respectively, to the scattering vector with a Gaussian function. [Figure 8] Figure 8 is a TEM image of the surface of an example of a pellicle film. [Figure 9] Figure 9 shows the selected-field diffraction pattern of a TEM image taken of the surface of an example of a pellicle film. [Figure 10] Figure 10 is a graph showing the diffraction intensity of the diffraction pattern in directions D2 and D3, respectively, in Figure 9, against the scattering vector of an example of a pellicle film. [Figure 11] Figure 11 is a TEM image of the surface of an example of a pellicle membrane. [Figure 12] Figure 12 is a TEM image showing the contour lines of each of the multiple CNTs in Figure 11. [Figure 13] Figure 13 shows an approximate curve drawn over the contour line C1 of the CNT in Figure 12. [Figure 14] Figure 14 is a TEM image of a cross-section of an example of a single bundle. [Figure 15] Figure 15 is a TEM image in which annular contour lines are drawn around each of the multiple CNTs shown in Figure 14. [Figure 16] Figure 16 shows a polygon obtained by connecting the center points of multiple ring-shaped contour lines in Figure 15 with straight lines. [Figure 17] Figure 17 shows the polygons in Figure 16. [Figure 18]Figure 18 shows a polygon in Figure 16 with the interiors of multiple ring-shaped outlines filled in black. [Figure 19] Figure 19 shows a polygon obtained by removing the cross-sections of CNTs located outside the polygon from the cross-sections of multiple CNTs in Figure 18. [Modes for carrying out the invention]

[0011] In this disclosure, a numerical range indicated using "~" means a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. In the numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In this disclosure, unless otherwise specified, the amount of each component refers to the total amount of multiple substances if there are multiple substances corresponding to each component. In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved. In this disclosure, "EUV light" refers to light with a wavelength of 1 nm or more and 30 nm or less. Preferably, the wavelength of the EUV light is between 5 nm and 13.5 nm. In this disclosure, “standard deviation” refers to the positive square root of the variance, and “variance” refers to the arithmetic mean of the squares of the deviations (i.e., the difference between the statistical value and the mean). In this disclosure, "film surface direction" refers to any direction parallel to the surface of the pellicle film, and "film thickness direction" refers to the thickness direction of the pellicle film. The film thickness direction is perpendicular to the film surface direction.

[0012] (1) First Embodiment (1.1) Pellicle membrane The pellicle film according to the first embodiment contains a plurality of carbon nanotubes (hereinafter referred to as "CNTs"). The average value of the linearity parameter of the plurality of CNTs, represented by the following formula (1), is 0.10 or less.

[0013] Equation (1): Linearity parameter = Standard deviation Sa of the width of a single CNT (hereinafter referred to as "single tube") / Mean value Aa of the width In equation (1), the standard deviation Sa and the mean value Aa are each calculated based on 11 measurements obtained by measuring the width of the single tube at 2 nm intervals along the longitudinal direction of the single tube.

[0014] The linearity parameter represents the coefficient of variation of the width of a single tube, quantitatively indicating the degree of variation in the width of the single tube. A linearity parameter closer to 0 indicates less variation in the width of the single tube and that the single tube is closer to a straight line.

[0015] In the following, the pellicle membrane may also be referred to as the "CNT membrane."

[0016] In the first embodiment, since the pellicle film has the above configuration, it is less prone to film reduction even when exposed to hydrogen plasma. This is presumed to be mainly due to the following reasons. A mean value of 0.10 or less for the linearity parameters of multiple CNTs indicates that each of the multiple CNTs has high linearity from a microscopic perspective and that the defect density of each structure of the multiple CNTs is low. In other words, a mean value of 0.10 or less for the linearity parameters of multiple CNTs indicates that the width of each of the multiple CNTs is not finely disordered like a saw blade along its longitudinal direction, and that the width of each of the multiple CNTs is nearly uniform. "A defect density of 0 in the structure of a CNT (i.e., no defect density in the structure of a CNT)" means that there are no missing carbon atoms in the network (mesh) of carbon atoms linked by covalent bonds, and that no topological defects have been introduced into the network (mesh). Topological defects include five-membered rings and seven-membered rings. Areas on the surface of CNTs that have structural defects tend to appear as areas exhibiting nonlinearity from a microscopic perspective (hereinafter referred to as "nonlinear regions"). Hydrogen plasma is thought to primarily promote the etching of CNTs (i.e., decomposition and removal of CNTs) starting from these nonlinear regions. The defect density of each structure of the multiple CNTs contained in the pellicle film according to the first embodiment is low. Therefore, the number of nonlinear regions that serve as starting points for etching by hydrogen plasma is small. As a result, it is presumed that the pellicle film according to the first embodiment is less prone to film reduction even when exposed to hydrogen plasma.

[0017] (1.1.1) Linearity parameter In the first embodiment, the average value of the linearity parameters of the multiple CNTs is 0.10 or less, and from the viewpoint of further suppressing the reduction of the pellicle film even when exposed to hydrogen plasma, it is preferably 0.08 or less, more preferably 0.07 or less, even more preferably 0.06 or less, particularly preferably 0.05 or less, and even more preferably 0.045 or less, and the closer to 0, the better. There are no specific restrictions on the lower limit of the mean value of the linearity parameter, but for example, it can be set to 0.001 or higher, 0.005 or higher, or 0.010 or higher. From these viewpoints, the average value of the linearity parameters of multiple CNTs is preferably 0.001 to 0.08, more preferably 0.001 to 0.07, even more preferably 0.001 to 0.06, particularly preferably 0.001 to 0.05, and even more preferably 0.001 to 0.045. From another viewpoint, the average value of the linearity parameters of multiple CNTs is preferably 0.005 to 0.06, more preferably 0.005 to 0.05, and even more preferably 0.005 to 0.045. From yet another viewpoint, the average value of the linearity parameters of multiple CNTs is preferably 0.010 to 0.06, more preferably 0.010 to 0.05, and even more preferably 0.010 to 0.045.

[0018] (1.1.1.1) Method for measuring linearity parameters The average value of the linearity parameter of multiple CNTs is measured as follows:

[0019] <Transcription> The self-supporting portion of the pellicle film, as described later, is transferred to a grid for observation using a transmission electron microscope (TEM). The "self-supporting portion of the pellicle film" refers to the area of ​​the pellicle film that is not supported by the pellicle frame. Specifically, a solvent is dropped onto the grid, and the pellicle film of the pellicle is placed facing the grid, with the pellicle on the grid. Examples of solvents include water and organic solvents. The solvent is dried to ensure the pellicle film is in close contact with the grid. The grid is fixed, and the pellicle frame of the pellicle is lifted to separate the self-supporting portion from the pellicle and transfer it to the grid.

[0020] <Surface observation> The surface of the self-supporting film portion transferred to the grid is observed using a TEM (magnification: 100,000x to 600,000x) from the direction of the thickness of the self-supporting film portion to obtain multiple first TEM images. The TEM resolution is preferably such that a length of 5 nm in the TEM image corresponds to 100 pixels or more, and more preferably such that a length of 5 nm corresponds to 200 pixels or more. From multiple first-stage TEM images, 20 CNTs (carbon nanotubes) are selected that allow for easy identification of the width of each individual CNT. Hereafter, each of the 20 selected carbon nanotubes will be referred to as a "single tube".

[0021] <Measurement> The linearity parameters of each of the 20 single tubes are measured. Specifically, for one of the 20 single tubes, the width of the single tube is measured at 2 nm intervals along the longitudinal direction of the single tube using the first TEM image, and the width of the single tube is measured at 11 points. Using the obtained 11 measurement points, the standard deviation Sa and the average value Aa of the single tube widths are calculated. Using the calculated standard deviation Sa and average value Aa, the linearity parameter of the single tube width is calculated from equation (1). Similarly, calculate the linearity parameter for the width of all 20 single tubes. The average value of the linearity parameters of the widths of the 20 single tubes is calculated. The average value of the linearity parameters of the widths of the 20 single tubes is considered to be the average value of the linearity parameters of multiple CNTs.

[0022] (1.1.2) Packing density parameters In the first embodiment, the plurality of CNTs form a bundle, and it is preferable that the average value of the packing density parameter of the plurality of bundles, represented by the following formula (2), is 0.20 or less.

[0023] Equation (2): Packing density parameter = Standard deviation Sb of the distance between the center points of multiple CNTs constituting one bundle (hereinafter referred to as "single bundle") / Average value Ab of the distance between the center points In equation (2), the distance between center points is the length of a straight line connecting the center points such that, in a transmission electron microscope image of a 20 nm × 20 nm range including a single bundle, obtained by cutting the pellicle film along the thickness direction of the pellicle film, the center point of each annular contour line of a plurality of CNTs in the transmission electron microscope image is identified, and a plurality of triangles satisfying predetermined conditions are formed. The aforementioned predetermined conditions include that the sides of the plurality of triangles do not intersect, that three center points are selected such that the sum of the lengths of the three sides of the triangles is minimized, and that the interior angle of the outermost triangle among the plurality of triangles is less than 120°. The standard deviation Sb and the mean Ab are each calculated based on a plurality of distances between center points that are less than or equal to a predetermined value. The predetermined value is obtained by multiplying the average value of the distances between the center points, from the shortest distance (1st) to the predetermined rank, by 1.6. The predetermined rank is represented by an integer obtained by rounding the first decimal place of the number obtained by multiplying the total number of distances between the multiple center points by 0.8.

[0024] In this disclosure, "total number of distances between multiple center points" refers to the total number of distances between multiple center points, and means the total number of straight lines connecting the center points.

[0025] The packing density parameter represents the coefficient of variation of the distance between the centers of the multiple CNTs constituting a single bundle, and quantitatively expresses the degree of variation in the distance between the centers of the multiple CNTs constituting the single bundle. A packing density parameter closer to 0 indicates that the variation in the distance between the centers of the multiple CNTs constituting the single bundle is small, meaning that the CNTs constituting the single bundle are packed tightly together in a hexagonal pattern.

[0026] The distance between center points with the outermost center points tends to be longer than the distances between other center points, and is prone to becoming noise when evaluating the packing density parameters of multiple bundles. In equation (2), the standard deviation Sb and the mean Ab are calculated based on multiple distances between center points that are less than or equal to a predetermined value, as described above, thereby eliminating such noise.

[0027] This section details the conditions used when calculating the average value of the packing density parameter. The predetermined conditions for triangulating a collection of CNT center points—namely, "that the sides of the multiple triangles do not intersect" and "that the three center points are selected such that the sum of the lengths of the three sides of the triangles is minimized"—are known as Delaunay's triangulation.

[0028] In the first embodiment, when triangulating a collection of CNT center points, in order to evaluate the distance between the center points of adjacent CNTs, in addition to the Delaunay triangulation conditions described above, the constraint condition "the interior angle of the outermost triangle is less than 120°" is added. Furthermore, when calculating the average value of the packing density parameter, the following calculation condition is imposed: "Each of the standard deviation Sb and the average value Ab is calculated based on multiple center-point distances that are less than or equal to a predetermined value among all center-point distances."

[0029] Generally, in Delaunay triangulation, a collection of points is connected in a convex hull. When triangulating a collection of points, a convex hull shape is formed by connecting two points located outside the collection of points to form an edge. In forming this convex hull shape, it is sometimes necessary to connect two points that are far apart from each other. In the first embodiment, the edge formed by connecting two center points of distantly located CNTs may not be an edge formed by connecting two center points of adjacent CNTs, but rather an edge formed by connecting the center points of two CNTs that are not adjacent to each other, spanning multiple CNTs. In this case, the length of the edge formed by connecting two distantly located points represents the distance between the center points of CNTs that are far apart from each other, rather than the distance between the center points of adjacent CNTs. To evaluate the packing state of CNTs, it is important to assess the distance between the center points of two adjacent CNTs that make up a bundle, as well as the distribution and turbulence of that distance. In other words, including the length of the side connecting two far-away center points of outer CNTs (center point distance) in the average value of the packing density parameter is inappropriate because it introduces a noise component that overestimates the packing density parameter.

[0030] For the reasons stated above, when performing triangulation of the set of CNT center points, adding the aforementioned constraints to Delaunay's triangulation conditions makes it possible to extract the distance between the center points of adjacent CNTs. Furthermore, when calculating the average value of the packing density parameter, the aforementioned calculation conditions are imposed, eliminating noise components that overestimate the packing density parameter. As a result, the packing density parameter, which is the coefficient of variation of the distance between the center points of multiple CNTs constituting a single bundle, is evaluated with good accuracy (less prone to noise components).

[0031] If the average value of the packing density parameters of multiple bundles is 0.20 or less, the pellicle film will be less prone to film loss even when exposed to hydrogen plasma. This is presumed to be mainly due to the following reasons: A packing density parameter of 0.20 or less on average for multiple bundles indicates that the multiple CNTs constituting a single bundle are densely packed and aggregated. As a result, hydrogen plasma cannot diffuse into the interior of the single bundle, making it less susceptible to etching and other effects caused by hydrogen plasma. Consequently, the pellicle film is presumed to be less prone to film loss even when exposed to hydrogen plasma.

[0032] The average value of the packing density parameters of the multiple bundles is preferably 0.20 or less, and more preferably 0.15 or less, more preferably 0.10 or less, from the viewpoint of further suppressing film loss of the pellicle film even when exposed to hydrogen plasma, the closer to 0, the better. An average value of the packing density parameters of the multiple bundles being 0 indicates that all of the multiple CNTs constituting a single bundle are arranged in a hexagonal crystal structure at equal intervals, i.e., it is a close-packed structure. The lower limit of the average value of the packing density parameters of multiple bundles is not particularly restricted and can be, for example, 0.01 or higher, 0.02 or higher, or 0.05 or higher. From these perspectives, the average value of the packing density parameters of multiple bundles is preferably 0.01 to 0.20, more preferably 0.01 to 0.15, even more preferably 0.01 to 0.10, particularly preferably 0.02 to 0.10, and even more preferably 0.05 to 0.10.

[0033] (1.1.2.1) Method for measuring packing density parameters Next, the method for measuring the packing density parameter of a bundle will be explained with reference to Figures 1 to 3. In Figure 2, reference numeral 10 indicates a single bundle, reference numeral 20 indicates the annular contour line of the CNT, and reference numeral 30 indicates the center point. In Figure 3, reference numeral 30 indicates the center point, reference numeral 40 indicates multiple triangles, and reference numeral 50 indicates a straight line that forms one side of a triangle.

[0034] The average value of the packing density parameters of multiple bundles is measured as follows:

[0035] <Transcription> The self-supporting portion of the pellicle film of the pellicle, as described later, is transferred onto the substrate. The substrate is not particularly limited and may be a silicon substrate. Specifically, a solvent is dropped onto the substrate, and the pellicle film of the pellicle is placed facing the substrate, and the pellicle is placed on the substrate. Examples of solvents include water and organic solvents. The solvent is dried to ensure that the pellicle film adheres tightly to the substrate without any gaps. The substrate is fixed and the pellicle frame of the pellicle is lifted to separate the self-supporting portion from the pellicle and transfer the self-supporting portion to the substrate.

[0036] <Cross-sectional observation> The transferred self-supporting film portion is cut in two places along the thickness direction of the self-supporting film portion using a focused ion beam apparatus to create a thin section for cross-sectional observation with a thickness of approximately 100 nm in the direction of transparency (perpendicular to the cross-section). The cross-section of the self-supporting film portion is observed using TEM (magnification: 50,000x to 400,000x) to obtain multiple second TEM images (see Figure 1). At this time, the self-supporting film portion may be encased in resin or laminated with metal or other materials to improve contrast. The resolution of the TEM is preferably such that a length of 5 nm in the TEM image corresponds to 100 pixels or more. From multiple second TEM images, select 10 bundles that allow for easy recognition of the cross-section of a single bundle. Hereafter, each of the 10 selected bundles will be referred to as a "single bundle".

[0037] <Measurement> The packing density parameter of each of the 10 single bundles is measured. Specifically, in the second TEM image covering a 20 nm × 20 nm range including the single bundles, the center point of the annular contour line of each of the multiple CNTs in the second TEM image is identified (see Figure 2). More specifically, as can be seen in Figure 1, when observing the second TEM images of the bundle and the CNTs that make up the bundle, the wall portions of the CNTs appear as dark ring-shaped lines. The ring-shaped contour lines are extracted for each CNT that makes up the bundle, so that the region of these dark ring-shaped lines becomes the contour line. In the second TEM image of CNTs with two or more layers, approximately concentric (or identically centrally located) annular lines can be seen at intervals of about 0.3 nm to 0.4 nm. Therefore, the contour lines are extracted so that the dark annular line region of the outermost layer becomes the contour line.

[0038] After extracting the contour lines of each of the multiple CNTs, the centroid coordinates of each annular contour line are calculated to identify the center point of each annular contour line of the multiple CNTs. The identified center points are connected by straight lines so that multiple triangles satisfying the following conditions (a) and (b) are formed (see Figure 3). The lengths of all the resulting straight lines (distances between center points) are measured. (a) The sides of the multiple triangles do not intersect. (b) Select three center points such that the sum of the lengths of the three sides of the triangle is minimized. (c) The interior angle of the outermost triangle among the multiple triangles is less than 120°.

[0039] From the measured lengths (distance between center points) of multiple lines obtained, multiple measurements below a predetermined value are identified. The predetermined value is obtained by multiplying the average value of the measurements from the shortest length (1st) to the predetermined rank by 1.6, in order of measurement length for all measurements. The predetermined rank is the same as the integer obtained by rounding the first decimal place of the number obtained by multiplying the total number of lines by 0.8. Specifically, as shown in Figure 3, if the total number of lines is 27, the predetermined rank is 22, which is obtained by multiplying 27 by 0.8 and rounding the resulting 21.6 to the nearest tenth. In this case, the predetermined value is obtained by multiplying the average value of the 27 measured values, from the shortest to the 22nd shortest, by 1.6.

[0040] Using multiple measurements below a predetermined value, the standard deviation Sb of the distance between the centers of the multiple CNTs constituting the single bundle and the average value Ab of the distance between the centers of the multiple CNTs constituting the single bundle are calculated. Using the calculated standard deviation Sb and average value Ab, the packing density parameter of the single bundle is calculated from equation (2). Similarly, calculate the packing density parameter for all 10 single bundles. The average value of the packing density parameters of the 10 single bundles is calculated. This average value of the packing density parameters of the 10 single bundles is considered as the average value of the packing density parameters of multiple bundles.

[0041] (1.1.3) Packing density of multiple CNTs constituting a single bundle The method for evaluating the packing density of multiple CNTs constituting a single bundle may differ from the evaluation method using the packing density parameter described above. For example, for a pellicle film consisting of multiple carbon nanotubes (CNTs), electron diffraction can be used to obtain an indicator of the packing of the multiple CNTs constituting a single bundle from the diffraction intensity information of the diffraction peaks. In the eDIPS method, multiple carbon nanotubes (CNTs) are formed by bundling together. Each of the multiple CNTs produced by the eDIPS method has a diameter of approximately 1.5 nm to 2 nm, and its structure is mainly single-walled or double-walled. In a pellicle film composed of multiple CNTs produced by the eDIPS method, the limited-field electron diffraction pattern of the surface of the pellicle film and the limited-field electron diffraction pattern of the cross-section of the pellicle film show a lattice spacing d = 0.40 nm (scattering vector q = 2.5 nm). -1 A peak originating from a single-bundle triangular lattice appears in the vicinity of ). The cross-section of the pellicle film is the plane obtained by cutting the pellicle film along the direction of the thickness of the pellicle film. This diffraction peak reflects the spacing between the multiple carbon nanotubes (CNTs) that make up a single bundle. Therefore, its diffraction intensity depends on the diameter and aggregation state of the CNTs that make up the single bundle, and is stronger the higher the packing density and the more regular the packing structure of the multiple CNTs that make up the single bundle. Furthermore, in the case of thin films with a thickness of about 2 nm to 50 nm, such as pellicle films, the number of single bundles and CNTs present in the field of view when observed with TEM (magnification: 20,000x to 100,000x) is small, resulting in a low number density of structures contributing to diffraction. Therefore, in order to obtain high diffraction intensity, the packing density of the multiple CNTs constituting the single bundle must be high, and the multiple CNTs constituting the single bundle must have a high degree of regularity. Furthermore, this diffraction peak reflects the lattice originating from the single bundle (i.e., the spacing between the multiple CNTs that make up the single bundle). Therefore, this diffraction peak appears perpendicular to the longitudinal direction (axial direction) of the single bundle and the CNTs. By utilizing these diffraction intensity characteristics and evaluating the diffraction intensity originating from a single bundle, the packing density of the multiple CNTs constituting a single bundle can be evaluated, as described in (1.1.3.1) and (1.1.3.2) below.

[0042] The grid spacing d is expressed as the reciprocal of the scattering vector q (1 / q). The scattering vector q is given by the following equation, where L is the distance from the pellicle film to the detection surface of the microscope detector, λ is the wavelength of the electron beam, and r is the distance from the center on the pellicle film to the diffraction spot.

[0043]

number

[0044] (1.1.3.1) First diffraction method of TEM (packing density of CNTs) In the following section, with reference to Figures 4 to 7, we will explain the analysis method for selected-field electron diffraction patterns obtained by irradiating the surface and cross-section of a pellicle film with an electron beam approximately perpendicular to it. In Figure 5, the symbol A1 represents the plotted diffraction intensity curve along the film thickness direction, the symbol A2 represents the plotted diffraction intensity curve along the film plane direction, and the symbol A3 represents the approximation curve. The unit of diffraction intensity in Figure 5 is the luminance of the 16-bit grayscale acquired by the CCD camera, and the units of diffraction intensity in Figures 6, 7, and 10 are the same. In Figure 6, the symbol A4 indicates a difference curve showing the difference between plotted curve A1 and approximate curve A3 for diffraction intensity in the film thickness direction, and the symbol A5 indicates a difference curve showing the difference between plotted curve A2 and approximate curve A3 for diffraction intensity in the film plane direction. In Figure 7, the symbol A6 indicates the fitting function in the film thickness direction, and the symbol A7 indicates the fitting function in the film plane direction.

[0045] First, the self-supporting portion of the pellicle film is transferred onto the substrate in the same manner as the packing density parameter measurement method described above (1.1.2.1). The transferred self-supporting portion is then cut along the thickness direction of the self-supporting portion using a focused ion beam apparatus to create a thin section approximately 100 nm thick for cross-sectional observation. An electron beam is irradiated approximately perpendicularly to the cross-section of the self-supporting portion to obtain a limited-field electron diffraction pattern (see Figure 4). The observation magnification is 30,000x, and the field size is a 30 nm diameter area including the thin film region. When the longitudinal direction (axial direction) of a single bundle is horizontal to the substrate surface, the longitudinal direction (axial direction) of the single bundle is perpendicular to the thickness direction. In this case, the diffraction pattern in the thickness direction has a peak originating from the triangular lattice of the single bundle at d=0.40nm (q=2.5nm). -1 It appears in the vicinity of ). On the other hand, the aforementioned peak hardly appears in the axial direction (film plane direction) of the single bundle of diffraction pattern.

[0046] Next, the diffraction intensities of the diffraction patterns in the film plane direction and the film thickness direction are plotted against the scattering vector q. This yields a plotted curve of diffraction intensity in the film thickness direction (see symbol A1 in Figure 5) and a plotted curve of diffraction intensity in the film plane direction (see symbol A2 in Figure 5).

[0047] In the film plane direction, no diffraction intensity originating from the single-bundle triangular lattice appears (see symbol A2 in Figure 5). An approximation curve, as shown by symbol A3 in Figure 5, is created so that the diffraction spectrum in the film plane direction serves as the baseline. The approximation curve is set to q = 1.0 nm. -1 ~4.0nm -1 Within the range, a function may be used in which the diffraction intensity monotonically decreases as the value of q increases.

[0048] The type of approximation curve for the diffraction profile is not particularly limited, but it is preferable to use a specific power function. With a specific power function, the slope (decrease rate) of the diffraction intensity curve is large when the value of q is small and decreases as the value of q increases. The power function is given by y as the diffraction intensity and q as the scattering vector [nm]. -1 When we consider ], for example, y=αq -β , (α and β are appropriate positive values). Specifically, in Figure 5, the approximation curve A3 is y = 119.42 × q -0.966 That is the case.

[0049] Next, q = 1.0 nm -1 ~4.0nm -1 Within this range, the difference between the diffraction profile of the pellicle film in the thickness direction and the diffraction profile of the pellicle film in the film plane direction and the above-mentioned approximation curve is calculated. This yields the difference curve in the thickness direction (see symbol A4 in Figure 6) and the difference curve in the film plane direction (see symbol A5 in Figure 6). The difference curve in the film thickness direction can be calculated, for example, by subtracting an approximation curve from the plotted diffraction intensity curve in the film thickness direction. The difference curve in the film plane direction can be calculated, for example, by subtracting an approximation curve from the plotted diffraction intensity curve in the film plane direction.

[0050] For each of the diffraction intensity in the thickness direction and the diffraction intensity in the film plane direction, and for the difference curve in the thickness direction and the difference curve in the film plane direction, q = 1.0 nm. -1 ~4.0nm -1 The peaks appearing within this range are fitted using a Gaussian function. One method for fitting using a Gaussian function is the nonlinear least squares method.

[0051] In a sample using a silicon wafer as the substrate for transferring the self-supporting film, the diffraction plot in the film thickness direction showed q = 3.7 nm. -1 A diffraction peak originating from the silicon wafer appears nearby. Therefore, a Gaussian function is fitted to this silicon wafer-derived peak. In other words, the diffraction peak originating from the single bundle (q=2.0nm) in the diffraction plot in the thickness direction is fitted. -1 ~3.0nm -1 The ) is extracted by fitting with a Gaussian function. This yields a fitting function in the film thickness direction (see symbol A6 in Figure 7) and a fitting function in the film surface direction (see symbol A7 in Figure 7).

[0052] The diffraction peak ratio (hereinafter also referred to as the "first diffraction peak ratio") is preferably 2 or higher, more preferably 5 or higher, and even more preferably 10 or higher. "First diffraction peak ratio" refers to q = 2.0 nm -1 ~3.0nm -1 Within this range, the ratio of the maximum value of the fitting function in the film thickness direction to the maximum value of the fitting function in the film surface direction is shown.

[0053] A higher first diffraction peak ratio indicates a denser packing density and fewer gaps among the multiple CNTs constituting the single bundle. Therefore, if the first diffraction peak ratio falls within the aforementioned range, the diffusion of hydrogen radicals into the single bundle is further suppressed. As a result, the pellicle film exhibits higher lifetime characteristics and is less prone to film degradation even when exposed to hydrogen plasma.

[0054] (1.1.3.2) Second Diffraction Method of TEM (Packaging Density of CNTs) Next, referring to Figures 8 to 10, we will explain the method for analyzing electron diffraction patterns obtained by irradiating the surface of a pellicle film with an electron beam for surface observation. In Figure 8, the symbol M indicates an example of an electron diffraction measurement region, and the symbol D1 indicates the longitudinal direction (axial direction) of a single bundle located within the measurement region M. In Figure 9, the symbol D2 indicates the direction in which the diffraction intensity originating from the single bundle triangular lattice is weak (hereinafter also referred to as the "low diffraction intensity direction"), and the symbol D3 indicates the direction in which the diffraction intensity originating from the single bundle triangular lattice is strong (hereinafter also referred to as the "high diffraction intensity direction"). In Figure 10, the symbol B1 represents the plotted diffraction intensity curve of the diffraction pattern in the low diffraction intensity direction, the symbol B2 represents the plotted diffraction intensity curve of the diffraction pattern in the high diffraction intensity direction, and the symbol B3 represents the approximation curve.

[0055] The pellicle film according to the first embodiment preferably contains a plurality of carbon nanotubes forming a bundle, and has a diffraction peak ratio (hereinafter also referred to as the "second diffraction peak ratio") of 1.3 or higher. The diffraction peak ratio represents the ratio of the height of the second Gaussian function, which is a component of the second fitting function obtained by fitting the second plot curve, to the height of the first Gaussian function, which is a component of the first fitting function obtained by fitting the first plot curve, in a limited-field diffraction image obtained by observing the surface of the pellicle film with a transmission electron microscope. In other words, the diffraction peak ratio represents (height of the second Gaussian function obtained by fitting the second plot curve) / (height of the first Gaussian function obtained by fitting the first plot curve). The first plotted curve is a profile of the diffraction intensity in the direction in which the diffraction intensity originating from the bundle lattice of the bundle is weak, relative to the scattering vector q. The second plotted curve is a profile of the diffraction intensity in the direction in which the diffraction intensity is strong relative to the scattering vector q. The first fitting function is defined as the scattering vector q = 1.5 nm. -1 ~4.0nm -1 Within this range, the baseline function common to the first plotted curve and the second plotted curve, and the peak center position of the first plotted curve are q = 2.0 nm -1 ~3.0nm-1 This is a curve represented by the sum of the first Gaussian function within the specified range. In other words, the first fitting function is the approximation curve of the first plotted curve. The first Gaussian function is obtained by taking the difference between the first plotted curve and the baseline function, where the peak center position is q = 2.0 nm. -1 ~3.0nm -1 This can be derived by fitting with a Gaussian function within the specified range. There are no restrictions on the fitting method, but for example, the least squares method can be used. The second fitting function is the baseline function and the peak center position of the second plot curve is q = 2.0 nm. -1 ~3.0nm -1 This curve is represented by the sum of the aforementioned second Gaussian function within the specified range. The second Gaussian function is obtained by taking the difference between the second plotted curve and the baseline function, where the peak center position is q = 2.0 nm. -1 ~3.0nm -1 This can be derived by fitting with a Gaussian function within the specified range. There are no restrictions on the fitting method, but for example, the least squares method can be used. The height of the first Gaussian function is such that the scattering vector q is q = 2.0 nm -1 ~3.0nm -1 The local maximum value of the first Gaussian function in the range is shown. The height of the second Gaussian function is determined when the scattering vector q is q = 2.0 nm. -1 ~3.0nm -1 The local maximum value of the second Gaussian function in the range is shown.

[0056] The following is about the scattering vector q being q = 1.5 nm -1 ~4.0nm -1 Within the specified range, the "baseline function common to the first plotted curve and the second plotted curve" is also simply called the "baseline function."

[0057] A higher value for the second diffraction peak ratio indicates a higher packing density of the multiple CNTs that make up the bundle (i.e., smaller gaps between adjacent CNTs). If the second diffraction peak ratio is within the above range, the diffusion of hydrogen radicals into the bundle is further suppressed. As a result, the pellicle film exhibits higher lifetime characteristics and is less prone to film degradation even when exposed to hydrogen plasma.

[0058] The following describes the method for measuring the second diffraction peak ratio. First, the self-supporting portion of the pellicle film is transferred to a grid for electron microscopy observation in the same manner as the linearity parameter measurement method described above (1.1.1.1). The surface of the transferred self-supporting portion is observed using a TEM (magnification: 20,000x to 100,000x) in a direction along the thickness of the self-supporting portion to determine the electron diffraction measurement site (see Figure 8). An electron beam is irradiated onto the measurement area approximately perpendicular to the film surface direction, and a limited field diffraction image with a field size of 50 nm to 120 nm is obtained when observed at a magnification of 100,000x.

[0059] In the obtained diffraction pattern, a peak originating from the triangular lattice of the single bundle is observed perpendicular to the longitudinal direction (axial direction) of the single bundle within the region where diffraction was measured, with d=0.40nm (q=2.5nm). -1 It appears in the vicinity of ).

[0060] Regarding the diffraction intensity of the diffraction pattern, plots are made for the scattering vector q in the low diffraction intensity direction (see symbol D2 in Figure 9) and the high diffraction intensity direction (see symbol D3 in Figure 9) (see Figure 10). This yields a first plotted curve in the low diffraction intensity direction and a second plotted curve in the high diffraction intensity direction.

[0061] The direction of high diffraction intensity is d=0.40nm (q=2.5nm) in the limited field diffraction pattern. -1 This can be determined from the fact that, in the range where the diffraction pattern of the electron beam transmission image is acquired, the bundle appears as bright lines and bright spots perpendicular to the longitudinal direction (axial direction) of the bundle. The direction of low diffraction intensity can be determined from the appearance of a dark region perpendicular to the axis in the limited-field diffraction pattern, relative to the axis in which the bundle is not extended within the range in which the diffraction pattern of the electron beam transmission image was acquired.

[0062] The first plotted curve shows the diffraction intensity profile in the low diffraction intensity direction relative to the scattering vector q. The second plotted curve shows the diffraction intensity profile in the high diffraction intensity direction relative to the scattering vector q.

[0063] The first plotted curve (see symbol B1 in Figure 10) and the second plotted curve (see symbol B2 in Figure 10) are each fitted to a Gaussian function using the difference between the first plotted curve and the baseline function, and the difference between the second plotted curve and the baseline function. This yields a first Gaussian function in the low diffraction intensity direction and a second Gaussian function in the high diffraction intensity direction. By using the first and second Gaussian functions obtained in this way to determine the second diffraction peak ratio, it becomes easier to evaluate whether the multiple CNTs constituting the single bundle are in a dense state, that is, whether the pellicle film is resistant to film loss even when exposed to hydrogen plasma. The first fitting function is expressed as the sum of the baseline function and the first Gaussian function. The second fitting function is expressed as the sum of the baseline function and the second Gaussian function. The baseline functions of the first fitting function and the second fitting function are identical.

[0064] The baseline function is the function common to both the first plotted curve B1 and the second plotted curve B2, where q = 1.5 nm. -1 ~4.0nm -1 It is preferable that the function is one in which the diffraction intensity monotonically decreases as the value of q increases within the specified range. It is even more preferable to use a power function for the baseline function such that the slope (decrease rate) of the diffraction intensity curve is large when the value of q is small, and decreases as the value of q increases. The power function can be, for example, y = αq, where y is the diffraction intensity and q is the scattering vector. -β , (α and β are appropriate positive values). Specifically, in Figure 10, the approximation curve B3 is y = 284.71 × q -1.441 That is the case.

[0065] The first Gaussian function can be expressed, for example, by the following equation [Equation 2]. In equation [Equation 2], a1 is the diffraction peak intensity, b1 is the peak position, and c1 is the peak width.

[0066]

number

[0067] The second Gaussian function can be expressed, for example, by the following equation [Equation 3]. In equation [Equation 3], a2 is the diffraction peak intensity, b2 is the peak position, and c2 is the peak width.

[0068]

number

[0069] The first Gaussian function is set to be an approximation of the difference between the first plotted curve and the baseline function. Specifically, if the first fitting function is Z1, the baseline function is Y, and the first Gaussian function is F1, then it can be expressed as, for example, Z1 = Y + F1. The first fitting function approximates the first plotted curve. The second Gaussian function is set to approximate the difference between the second plotted curve and the baseline function. Specifically, if the second fitting function is Z2, the baseline function is Y, and the second Gaussian function is F2, then it can be expressed as, for example, Z2 = Y + F2. The second fitting function approximates the second plotted curve.

[0070] The second diffraction peak ratio is preferably 1.3 or higher, more preferably 1.5 or higher, more preferably 2 or higher, and even more preferably 5 or higher. There is no particular upper limit to the second diffraction peak ratio; for example, it can be 100 or less, 50 or less, or 20 or less. From these viewpoints, the second diffraction peak ratio is preferably 1.3 to 100, more preferably 1.5 to 100, even more preferably 1.5 to 50, particularly preferably 1.5 to 20, even more preferably 2 to 20, and even more preferably 5 to 20.

[0071] (1.1.4) Smoothness evaluation value (linearity of CNTs) Next, referring to Figures 11 to 13, we will explain a method for quantifying the linearity of CNTs using a smoothness evaluation value. In Figure 12, reference numeral 11 indicates the contour line of a carbon nanotube (CNT). In Figure 13, the symbol C1 indicates the contour line of the CNT, and the symbol C2 indicates the approximation curve.

[0072] The pellicle film according to the first embodiment includes a plurality of carbon nanotubes forming a bundle, and the smoothness evaluation value is 0.070 (nm). 2 It is preferable that it is less than or equal to / nm. The smoothness evaluation value is the value obtained by dividing the area between the contour line of the carbon nanotube and the approximation curve of the contour line by the length of the approximation curve. The aforementioned contour line is obtained by tracing the wall portion of the CNT that appears as a dark line in a transmission electron microscope image of the surface of the pellicle film at a resolution of 100 pixels or more for a length of 5 nm. The aforementioned approximation curve is a curve drawn by quadratic spline interpolation of the coordinates of the contour line of the CNT. The outline and approximate curve of the carbon nanotube are extracted from 20 carbon nanotubes. The length of the outline is 20 nm for each carbon nanotube.

[0073] If the smoothness evaluation value falls within the range described above, the defect density of each CNT structure is low, and the number of non-linear regions that serve as etching starting points by hydrogen plasma is small. The distance between the centers of the multiple CNTs constituting a single bundle is short, and multiple CNTs form a single bundle. Furthermore, due to the high linearity, CNT chains can be adjacent to each other with small gaps. As a result, the packing density of CNTs within the single bundle increases. Consequently, even if the pellicle film is exposed to hydrogen plasma, film loss of the pellicle film can be suppressed.

[0074] The method using the smoothness evaluation value employs a transmission electron microscope image (see Figure 11) of the pellicle film observed from the film surface direction. The method using the smoothness evaluation value comprises an extraction step, an approximation curve creation step, an area calculation step between curves step, and a calculation step, and each step is performed in this order. In the extraction process, the contour lines of the CNTs are extracted (see Figure 12). In the approximation curve creation process, an approximation curve is created for the contour line of the CNT (see Figure 13). In the curve area calculation process, the area between the approximation curve and the contour line of the CNT is calculated. The "area between the approximation curve and the contour line of the CNT" refers to the total area of ​​multiple parts enclosed by the approximation curve and the contour line of the CNT. In the calculation process, the CNT smoothness evaluation value is calculated by dividing the area calculated in the curve area calculation process by the length of the approximation curve (i.e., curve area normalization).

[0075] (1.1.4.1) Extraction process Specifically, first, the self-supporting portion of the pellicle film is transferred to a grid for electron microscopy observation in the same manner as the linearity parameter measurement method described above (1.1.1.1). An electron beam is shone onto the surface of the self-supporting portion approximately perpendicular to the film plane direction, and the surface of the self-supporting portion is observed from the thickness direction of the self-supporting portion at a magnification of 100,000 to 600,000 times with a resolution of 5 nm length of 100 pixels or more, to obtain multiple third TEM images (see Figure 11). From multiple 3D TEM images, 20 CNTs are selected that clearly allow for the identification of a contour line originating from a single CNT. In the third TEM image, the wall portion of the carbon nanotube (CNT) appears as a dark line. By tracing this dark area, the "outline of the CNT" used in the extraction process can be extracted. In the third TEM image, typically two contour lines can be observed from a single carbon nanotube (CNT). Four contour lines can be observed from a two-layer CNT, and 2n contour lines can be observed from an n-layer CNT, where n is a natural number. If the selected CNT has two or more layers, the contour line of the outermost CNT is extracted as the "CNT contour line" in the extraction process. Extract the "contour of each CNT" from the 20 selected CNTs.

[0076] (1.1.4.2) Approximate curve creation process For each of the 20 selected carbon nanotubes (CNTs), obtain the contour coordinates of one of the two contour lines of the CNT. For each CNT, the length of the contour line to be drawn will be 20 nm (see Figure 12). The "length of the contour line to be drawn" refers to the distance between the start point and the end point of the contour line, drawn with a straight line. This creates the outline of the CNT with the horizontal and vertical axes representing the number of pixels (see symbol C1 in Figure 13). The symbol "C1" in Figure 13 represents the outline of the CNT in Figure 12, drawn using the method described above. In Figure 13, the horizontal and vertical axes represent the number of pixels. An approximate curve is created using spline interpolation based on the coordinates of the CNT contour line (see symbol C2 in Figure 13). At this time, the approximate curve is created so that the average difference between the approximate curve and the CNT contour line per unit length (=1 nm) is 0.2 [nm] or less. The order of the spline interpolation can be any as long as the above conditions are satisfied, but it is preferably a second-order or third-order spline interpolation, and more preferably a second-order spline interpolation. The "difference between the approximation curve and the CNT contour line" refers to the difference in values ​​on the vertical axis between a point on the CNT contour line and a point on the approximation curve at a given point X on the horizontal axis. The average of these differences represents the average distance within a predetermined range on the horizontal axis (a length of 1 nm of the contour line).

[0077] (1.1.4.3) Curve area calculation process Area between the approximation curve and the contour line of the CNT [nm] 2 Calculate the area between the approximation curve and the contour line of the CNT [nm]. 2 The method for calculating [ ] is not particularly limited and any known method is acceptable; for example, commercially available software may be used.

[0078] (1.1.4.4) Calculation process The length of the approximation curve [nm] is calculated. In the example shown in Figure 13, the length of the approximation curve corresponds to the length of the approximation curve C2 at the pixel corresponding to the length of the extracted CNT contour line, which is 20 nm. Specifically, in Figure 13, the length of the approximation curve represents the length of the approximation curve from one end, 500 pixels on the horizontal axis and 2207 pixels on the vertical axis, to the other end, 2010 pixels on the horizontal axis and 2085 pixels on the vertical axis. Area between the approximation curve and the contour line [nm] 2 By dividing ] by the length of the approximation curve [nm], the area [nm] between the approximation curve and the contour line per unit length is obtained. 2 Calculate the area per unit length (hereinafter also referred to as "area per unit length"). For each of the 20 contour lines, the area per unit length [nm] 2 The area per unit length [nm] is calculated for each contour line. Then, the average value of the calculated area per unit length [nm] is determined. The average value of the area per unit length for the 20 contour lines is used as the smoothness evaluation value.

[0079] The smoothness evaluation value is preferably 0.070 [nm] 2 [nm] or less, more preferably 0.050[nm] 2 [nm] or less, more preferably 0.036[nm] 2 [nm] or less, more preferably 0.034[nm] 2 The smoothness evaluation value is 0 [nm] or less. 2 The closer the value is to [ / nm], the higher the linearity of the CNT. The lower limit of the smoothness evaluation value is not particularly limited, for example, 0.001 (nm). 2It can be 0.005 (nm) or more, and 0.005 (nm) 2 It can be set to 0.010 (nm) or higher, and 0.010 (nm) 2 It can also be set to 1 / nm or higher. From these perspectives, the smoothness evaluation value is preferably 0 (nm). 2 / nm)~0.070(nm 2 / nm), more preferably 0(nm) 2 / nm)~0.050(nm 2 / nm), more preferably 0(nm) 2 / nm)~0.036(nm 2 / nm), more preferably 0.001(nm) 2 / nm)~0.036(nm 2 / nm), more preferably 0.005(nm) 2 / nm)~0.036(nm 2 / nm), particularly preferably 0.010(nm) 2 / nm)~0.036(nm 2 / nm), more preferably 0.010(nm) 2 / nm)~0.034(nm 2 It is / nm).

[0080] The above-mentioned steps, such as extracting the coordinates of the contour line, measuring the length of the approximation curve, and calculating the area between the approximation curve and the contour line of the CNT, may be performed on a pixel-by-pixel basis, with one pixel of the image being the smallest unit, and then the length per pixel may be converted from the image's magnification and scale at the end.

[0081] (1.1.5) Average value of the percentage of void area (packing density of CNTs) Next, referring to Figures 14 to 19, we will explain a method for calculating the packing density parameters of multiple bundles, which utilizes area obtained by image analysis of TEM images of the cross-section of the pellicle membrane (hereinafter referred to as the "second method"). In Figure 15, reference numeral 12 indicates the contour line of a carbon nanotube (CNT). In Figure 16, reference numeral 12 indicates the outline of a CNT, reference numeral 32 indicates the center point of the annular outline, reference numeral 42 indicates a polygon, and reference numeral 52 indicates a straight line that forms one side of the polygon. In Figure 18, reference numeral 62 indicates a cross-section of a CNT. Reference numeral 65 indicates the gap between adjacent CNT cross-sections 62 within the polygon 42.

[0082] The second method uses cross-sectional images of carbon nanotubes (CNTs). The second method comprises an extraction step, a center point acquisition step, a first calculation step, a second calculation step, and a third calculation step, and each step is performed in this order. In the extraction process, the contour lines of the carbon nanotubes (CNTs) are extracted from the cross-sectional image of the CNTs. In the center point acquisition process, the geometric center of the contour line of the cross-section of the CNT is calculated to obtain the center point coordinates. In the first calculation step, a polygon is created using the center point coordinates, and the area (TA) of the polygon is calculated. In the second calculation step, the total area (TB) of the internal contour region of the cross-section of the CNTs within the polygon is calculated. In the third calculation step, the ratio of the area that will be a gap is calculated from the relationship (TA-TB) / TA.

[0083] First, the self-supporting portion of the pellicle film is transferred to the substrate in the same manner as the packing density parameter measurement method described above (1.1.2.1). The transferred self-supporting portion is cut along the thickness direction of the self-supporting portion. The cross-section of the self-supporting portion is observed using a TEM (magnification: 50,000x to 400,000x; preferably an observation magnification where 5nm is represented by 100 pixels or more) to obtain multiple 4th TEM images (see Figure 14). From the multiple 4th TEM images, 10 single bundles are selected that are easy to recognize the cross-section of a single bundle. The TEM resolution is preferably such that 5nm is represented by 100 pixels or more in the TEM image.

[0084] Next, in the 4th TEM image in the 20 nm × 20 nm range, including a single bundle, the center point of each annular contour line of multiple CNTs in the 4th TEM image is identified (see Figure 16). More specifically, as shown in Figure 14, when a single bundle and the CNTs that make up the single bundle are observed from the cross-sectional direction of the single bundle, the wall surface of the CNT appears as a dark annular line. The annular contour lines are extracted for each CNT that makes up the single bundle, so that the region of this dark annular line becomes the contour line. In TEM images of cross-sections of CNTs with two or more layers, approximately concentric (or identically centered) annular lines can be observed at intervals of about 0.3 nm to 0.4 nm. Therefore, the contour lines are extracted so that the dark annular line region of the outermost layer becomes the contour line (see Figure 15). After extracting the contour lines of each of the multiple CNTs, the centroid position coordinates of each annular contour line are calculated to identify the center point of each annular contour line of the multiple CNTs. Connect the identified center points with straight lines so that multiple triangles satisfying the following conditions (a) to (d) are formed (see Figure 16). (a) The sides of the multiple triangles do not intersect. (b) Select three center points such that the sum of the lengths of the three sides of the triangle is minimized. (c) The interior angle of the outermost triangle is less than 120°. (d) The length of all sides, counting from the shortest side, must be no more than 1.6 times the average length of all sides that account for 80% or less of the total length of the sides.

[0085] A polygon is created by connecting the outermost edges of a triangularly divided figure (see Figure 17).

[0086] Calculate the area (TA) of the polygon. The area (TA) of the polygon is shown, for example, the area of ​​polygon 42 in Figure 17. The area (TB) inside the contour line within the polygon is calculated. The area (TB) inside the contour line represents, for example, the area of ​​the cross-section 62 of multiple CNTs located inside polygon 42 in Figure 19 (i.e., the black area inside polygon 42). Calculate the unfilled area within the polygon (=TA-TB). This is the gap area. The gap area represents, for example, the total area of ​​the multiple gaps 65 in Figure 19. By dividing this gap area by the area of ​​the polygon, we can calculate the proportion of the gap area within the polygon. The ratio of the gap area is (TA-TB) / TA.

[0087] For each of the 10 bundles, calculate the percentage of the gap area and then find the average of these 10 values.

[0088] The average percentage of the gap area is preferably 30% or less, more preferably 25% or less, and even more preferably 20% or less. If the average ratio of the gap area is within the range described above, the distance between the centers of the multiple CNTs constituting the single bundle is short, and the CNTs constituting the single bundle are filled with small gaps between them, making it less susceptible to film loss even when exposed to hydrogen plasma.

[0089] (1.1.6) Defect (G / D) distribution When carbon nanotubes (CNTs) react with hydrogen plasma and are etched, it is thought that defects on the CNT surface act as an initiation point, causing the etching reaction to proceed. By analyzing the linearity of CNTs using electron microscopy, it is possible to evaluate the topological defect density of CNTs. However, it is thought that not only topological defects, but also structural defects on the CNT surface caused by oxidation reactions, etc., react with hydrogen plasma, causing etching reactions of the CNTs to proceed. In addition to electron microscopy, methods other than those used for electron microscopy to evaluate structural defects such as topological defects and oxidation include techniques such as Raman spectroscopy.

[0090] Raman analysis using CNTs as a sample showed a D-band (Raman shift: approximately 1350 cm²). -1 ) strength and G-band (Raman shift: approximately 1580cm) -1 A common method for evaluating the quality and purity of CNTs is to use the ratio of their strength to the strength of the carbon nanotube (CNT). The G band is the primary Raman-activated mode of the graphite structure, originating from sp2-bonded carbons that represent the planar structure of carbon nanotubes. On the other hand, the D band is a mode derived from disorder and defects, such as structural defects and open ends of carbon nanotubes. In typical Raman spectroscopy, the Raman spectrum of a CNT thin film reflects the average structure of CNT chains present within the irradiated area where the laser is shone onto the CNT thin film. In a typical micro-Raman spectrometer, the laser irradiation size is approximately 1 μm in diameter. For a CNT thin film with a thickness of approximately 15 nm consisting of single-walled CNTs, the total length of single-walled CNTs contained within a 1 μm diameter spot is estimated to be approximately 1000 μm to 2000 μm. Furthermore, assuming a length of 1 μm per CNT, the total number of CNTs constituting the CNT thin film within the 1 μm spot system is approximately 1000 to 2000. Therefore, the structural information obtained with a typical micro-Raman spectrometer reflects the average structural information of CNTs of 1000 or more strands (length of 1000 μm or more).

[0091] The etching reaction of CNT thin films using hydrogen plasma is a nanoscale reaction that occurs on the surface of a single CNT. Therefore, the average defect information at the macroscale mentioned above is not important; what matters is the scale defect density that occurs in local CNT bundles between 10 nm and 100 nm. For example, consider the following two cases with different defect distributions for 1,000 carbon nanotubes (CNTs) of 1 μm length contained within a 1 μm field of view. One such case is when "a 1,000-cell carbon nanotube (CNT) with a length of 1 μm contains a total of 1,000 defects, and each of these defects is dispersed across different CNT locations (1,000 locations) without being adjacent to any one another." Another case is when "about 10 defects are adjacent to or localized in one location on a single CNT, and such defect clusters are distributed across 100 CNTs." In the two cases described above, where the defect distribution differs, the etching reactivity of hydrogen radicals is expected to differ, and etching is likely to proceed more easily in CNTs where the defects are adjacent and localized.

[0092] Micro-Raman spectroscopy with a spot size of approximately 1 μm makes it difficult to detect the differences in defect distribution described above. Therefore, it is necessary to use a defect density evaluation method with a smaller spatial resolution, specifically one with a spatial resolution of 100 nm or less. In addition to linearity evaluation using electron microscopy, tip-enhanced Raman scattering (TERS) is another method for evaluating defect density at the nanoscale. In TERS, when excitation light is shone on the tip of a probe with a nanostructure, localized surface plasmons are generated at the probe tip. By measuring the Raman scattered light enhanced by these localized surface plasmons, Raman imaging with nanoscale spatial resolution becomes possible. By combining morphological observation using AFM with Raman imaging using TERS, it is possible to simultaneously acquire AFM images and Raman mapping images with nanoscale spatial resolution. As a device that combines AFM measurement and Raman spectroscopy, for example, an AFM-Raman spectrometer (device name: XploRA nano) manufactured by Horiba, Ltd. can be used. For the analysis of CNTs using AFM and Raman spectroscopy, see, for example, the non-patent literature (EPJ Techniques and Instrumentation volume 2, Article number: 9 (2015) Tip-enhanced Raman spectroscopy: principles and applications Naresh Kumar, Sandro Mignuzzi, Weitao Su, Debdulal Roy).

[0093] The pellicle film according to the first embodiment is It contains multiple carbon nanotubes (CNTs) forming a bundle, It is preferable that the minimum value of the ratio of the intensity of the G band to the intensity of the D band (G / D) at seven locations within a predetermined bundle region in the cross-section of the pellicle film cut along the axial direction of the bundle is 0.80 or greater. The intensity of the D band and the intensity of the G band are measured values ​​obtained by Raman imaging. The predetermined bundle region refers to a region within a bundle with a thickness of 10 nm or more, with a spatial resolution of 20 nm or less, within the 500 nm × 500 nm measurement area of ​​the cross-section. The intensity of the aforementioned D band is when the Raman shift is 1300 cm. -1 ~1400cm -1 This is the maximum value of Raman scattering intensity within the specified range. The intensity of the aforementioned G-band is when the Raman shift is 1550 cm. -1 ~1610cm -1 This is the maximum value of Raman scattering intensity within the specified range.

[0094] A ratio (G / D) within the above range means that there are few defects on the CNT surface. Therefore, when CNTs react with hydrogen plasma and are etched, the etching reaction of the CNTs proceeds slowly.

[0095] The lower limit of the ratio (G / D) is preferably 1 or more, more preferably 2 or more, and more preferably 5 or more. There is no particular upper limit on the ratio (G / D); for example, it can be 100 or less, 50 or less, or 20 or less. From these viewpoints, the ratio (G / D) is preferably 0.80 to 100, more preferably 1 to 100, more preferably 2 to 100, even more preferably 2 to 50, particularly preferably 2 to 20, and even more preferably 5 to 20. Furthermore, the seven measurement points used in Raman imaging can be spaced 30 nm apart.

[0096] (1.1.7) Method for evaluating the first lifetime of the pellicle membrane As a method for evaluating the lifetime of the pellicle film, a method of irradiating the CNT film with EUV light in a hydrogen atmosphere using an EUV light source such as a synchrotron may be used.

[0097] The irradiation intensity of EUV is preferably 5 W / cm 2 or more and 60 W / cm 2 or less, and more preferably 10 W / cm 2 or more and 50 W / cm 2 . At present, the EUV irradiation intensity used in mass production of semiconductor devices is about 20 W / cm 2 , and the light source intensity used for CNT is assumed to be 30 W / cm 2 or more. Therefore, it is preferable to irradiate the CNT film with EUV light at an irradiation intensity close to the environment used in mass production of semiconductor devices. When the pellicle film is irradiated with high-intensity EUV light, the pellicle film absorbs the EUV light and reaches a temperature of 500°C or higher. Therefore, the temperature rise effect on the etching reaction can be reflected in the evaluation result of the lifetime of CNT. The irradiation area of EUV is preferably 0.5 mm 2 or more. When the shape of the irradiation area is a rectangular shape, the aspect ratio is preferably 10 or less. The "aspect ratio" indicates the ratio of the length of the long side to the length of the short side. Regarding the EUV irradiation area, if the area is 0.5 mm 2 or more and the aspect ratio is 10 or less, the temperature rise suppression effect due to the heat conduction of the pellicle film can be prevented in the area irradiated with EUV.

[0098] The pressure of hydrogen is more preferably 0.1 Pa or more and 100 Pa or less, and even more preferably 1 Pa or more and 50 Pa or less. The pressure of hydrogen may be high for accelerating the test.

[0099] Repeating the EUV light irradiation (hereinafter also referred to as "irradiation ON") and not irradiating EUV light (hereinafter also referred to as "irradiation OFF"), or scanning the beam, may perform a heating and cooling cycle. In the actual EUV exposure environment, since the EUV light is scanning on the pellicle, the heating and cooling of the pellicle film are repeated. Therefore, by performing the cycle or scanning of irradiation ON and irradiation OFF of EUV light in the EUV irradiation experiment, the actual exposure environment can be mimicked. The period of heating and cooling is preferably 0.01 seconds or more and 2 seconds or less, and more preferably 0.1 seconds or more and 1 second or less. Also, the duty ratio of irradiation ON and irradiation OFF (ON period / 1 cycle period) is preferably 0.01 or more and 0.8 or less, and even more preferably 0.1 or more and 0.5 or less.

[0100] The change rate of the first transmittance is preferably 2% or less, and more preferably 1% or less. The "change rate of the first transmittance" indicates the ratio (%) of the transmittance of the pellicle film after the first irradiation to the transmittance of the pellicle film before the first irradiation on the pellicle film. The "first irradiation" means that the hydrogen pressure is 5 Pa, the duty ratio is 1, the irradiation intensity is 30 W / cm 2 ~40 W / cm 2 and the total time that EUV light hits the pellicle film is 60 minutes of irradiation. The change amount of the first film thickness is preferably 6 nm or less, and more preferably 3 nm or less. The "change amount of the first film thickness" indicates the ratio (%) of the film thickness of the pellicle film after the first irradiation to the film thickness of the pellicle film before the first irradiation on the pellicle film.

[0101] The duty ratio may be changed as follows. The change rate of the second transmittance is preferably 2% or less, and more preferably 1% or less. The "change rate of the second transmittance" indicates the ratio (%) of the transmittance of the pellicle film after the second irradiation to the transmittance of the pellicle film before the second irradiation on the pellicle film. The "second irradiation" means that the hydrogen pressure is 5 Pa, the duty ratio is 0.01~0.8, the irradiation intensity is 30 W / cm 2~40W / cm 2 This indicates irradiation where the pellicle film is exposed to EUV light for a total of 60 minutes. The change in the second film thickness is preferably 6 nm or less, more preferably 3 nm or less. The "change in the second film thickness" represents the ratio (%) of the thickness of the pellicle film after the second irradiation to the thickness of the pellicle film before the second irradiation.

[0102] (1.1.8) Second Lifetime Evaluation Method for Pellicle Films Methods using gas species other than hydrogen plasma can be used to evaluate the lifetime of pellicle films. Oxygen plasma, argon plasma, nitrogen plasma, ammonia plasma, etc., may be used as the gas species. The lifetime evaluation method for pellicle films may also involve using a so-called remote plasma treatment technique in the plasma treatment process. In the remote plasma treatment technique, the plasma generation chamber and the treatment chamber are separated, and the treatment is performed in an environment free from electric field effects. A method for evaluating the lifetime of a pellicle film may involve reacting hydrogen gas on a hot tungsten catalyst to generate atomic hydrogen, and then exposing the pellicle film to this atomic hydrogen.

[0103] (1.1.9) Structure of the pellicle membrane In the first embodiment, the structure of the pellicle film is preferably a nonwoven fabric structure (irregular mesh structure) made up of multiple CNTs. This allows the pellicle film to be permeable. Specifically, during EUV exposure, the pellicle film connects the internal space of the pellicle with the external space of the pellicle. The "internal space of the pellicle" refers to the space surrounded by the pellicle and the photomask. The "external space of the pellicle" refers to the space not surrounded by the pellicle and the photomask. As a result, during EUV exposure, the pellicle film can easily create a vacuum or reduced pressure environment in the internal space of the pellicle. Since carbon nanotubes (CNTs) are typically fibrous, the pellicle membrane tends to have a nonwoven fabric structure overall.

[0104] (1.1.10) Pellicle film thickness In the first embodiment, the thickness of the pellicle film is not particularly limited and can be, for example, 2 nm to 200 nm. From the viewpoint of increasing the transmittance of EUV light, the thickness of the pellicle film is preferably 100 nm or less, more preferably 50 nm or less, even more preferably 40 nm or less, very preferably 30 nm or less, and particularly preferably 20 nm or less. From the viewpoint of the pellicle film's susceptibility to damage and its ability to shield against foreign matter (i.e., preventing foreign matter from passing through the pellicle film), the thickness of the pellicle film is preferably 4 nm or more, more preferably 6 nm or more, and even more preferably 10 nm or more. From these viewpoints, the thickness of the pellicle film is preferably 2 nm to 100 nm, more preferably 2 nm to 50 nm, even more preferably 2 nm to 40 nm, particularly preferably 2 nm to 30 nm, and even more preferably 4 nm to 30 nm.

[0105] (1.1.10.1) Method for measuring film thickness The thickness of the pellicle film is determined by transferring the self-supporting portion of the pellicle film (described later) onto a silicon substrate and using a reflectance spectrophotometer (F50-UV, manufactured by Filmetrics). For more details, the film thickness is measured as follows:

[0106] <Transcription> The self-supporting portion of the pellicle film of the pellicle, as described later, is transferred onto a silicon substrate. Specifically, a solvent is dropped onto the silicon substrate, and the pellicle film of the pellicle is placed facing the silicon substrate, thereby placing the pellicle on the substrate. Examples of solvents include water and organic solvents. The solvent is dried to ensure that the pellicle film adheres tightly to the silicon substrate without any gaps. The silicon substrate is fixed, and the pellicle frame of the pellicle is lifted to separate the self-supporting portion from the pellicle, thereby transferring the self-supporting portion to the substrate.

[0107] <Measurement of Reflectance Spectrum> For each measurement point of the self-supporting film transferred onto the silicon substrate, the reflectance spectrum is measured in the wavelength range of 200 nm to 600 nm, with a wavelength interval of 1 nm to 2 nm. For measuring the reflectance spectrum, a reflectance spectrometer (e.g., Filmetrics, model: F50-UV, spot diameter 1.5 mm) is used as the reflectance measuring device. A silicon wafer is used as the reference for measuring the reflectance intensity. The reflectance Rs(λ) can be calculated using the following formula.

[0108]

number

[0109] Here, Is(λ) represents the reflectance intensity of the freestanding film on the silicon substrate at wavelength λ, Iref(λ) represents the reflectance intensity of the reference, and Rref(λ) represents the absolute reflectance of the reference. When a silicon wafer is used as a reference, the optical constants of the silicon wafer are known, so Rref(λ) can be calculated. The gain, exposure time, etc., are the same for both the reference and the reflection intensity measurement of the self-supporting film on the silicon substrate. This allows the absolute reflectance of the self-supporting film on the silicon substrate to be obtained.

[0110] <Calculation of film thickness> Using the optical constants (refractive index: n, extinction coefficient: k) shown in Table 1 as the optical constants of the CNT film, and employing a three-layer model consisting of an air layer, a CNT film layer, and a silicon substrate, the reflectance spectrum in the wavelength range of 225 nm to 500 nm is analyzed by the least squares method to calculate the film thickness at each measurement point of the self-supporting film. The film thickness at the "measurement position" of the self-supporting film is the average of the film thicknesses of the nine measurement points included in the "measurement position" of the self-supporting film. The shape of the self-supporting film when viewed from the direction of film thickness is rectangular. The diagonals of the self-supporting film are defined as the X and Y axes. Three measurement points are set in the X-axis direction at intervals of 2 mm between the centers of adjacent measurement points, and three measurement points are set in the Y-axis direction at intervals of 2 mm between the centers of adjacent measurement points. In other words, a total of nine measurement points (3 vertical x 3 horizontal) are set as the "measurement position". The following describes a method for calculating the film thickness at each measurement point of the self-supporting film by analyzing the reflectance spectrum in the wavelength range of 225 nm to 500 nm using the least squares method.

[0111] [Table 1]

[0112] The thickness of the self-supporting film is calculated using a three-layer model consisting of an air layer, a CNT film layer, and a silicon substrate, using the following relational equations (a) to (c).

[0113] The reflectance Rs is equal to the amplitude reflectance r s It can be expressed using the following equation (a).

[0114]

number

[0115] In equation (a) above, * represents the complex conjugate.

[0116] Amplitude reflectance r from three layers: air layer / CNT film layer / silicon substrate s This can be expressed by the following equation (b).

[0117]

number

[0118] In the above formula (b), r 01 represents the amplitude reflectance from the interface between the air layer and the self-supporting membrane layer, and r 12 represents the amplitude reflectance from the interface between the self-supporting film layer and the silicon substrate layer, and i represents the imaginary unit. In equation (b) above, δ is the phase difference that occurs when light of wavelength λ travels back and forth once within the film, and is expressed by the following equation (c).

[0119]

number

[0120] In equation (c) above, d represents the thickness of the self-supporting film, N represents the complex refractive index (N=n-ik), and φ represents the angle of incidence. i represents the imaginary unit.

[0121] The thickness of the self-supporting film portion can be obtained by using the least squares method, with the thickness d as the variable for the reflectance Rs in the wavelength range of 225 nm to 500 nm, using the relational equations (a) to (c) above. The calculated thickness of the self-supporting film at the "measurement position" is considered to be the thickness of the pellicle film.

[0122] (1.1.11) Antioxidant layer In the first embodiment, the pellicle film may include an antioxidant layer. The antioxidant layer is laminated on at least one main surface of the pellicle film. This suppresses oxidation of the pellicle film during EUV light irradiation or pellicle storage.

[0123] The material of the oxidation-preventive layer is not particularly limited as long as it is a material that is stable against EUV light. For example, the material of the oxidation-preventive layer is SiO x (x≦2), Si x N y (x / y is 0.7 to 1.5), examples include SiON, Y2O3, YN, Mo, Ru, Rb, Sr, Y, Zr, Nb, or Rh.

[0124] The thickness of the antioxidant layer is preferably 1 nm to 10 nm, more preferably 2 nm to 5 nm, from the viewpoint of suppressing the absorption of EUV light by the antioxidant layer and suppressing the decrease in the transmittance of EUV light of the pellicle film.

[0125] (1.1.6) CNT In the first embodiment, the pellicle film includes a plurality of carbon nanotubes (CNTs). As a result, the pellicle film has superior mechanical strength compared to pellicle films made of materials such as SiN or polysilicon.

[0126] The structure of the CNT is not particularly limited and may be single-walled or multi-walled. Hereafter, single-walled carbon nanotubes (CNTs) will be referred to as "single-layered CNTs," and multi-walled CNTs will be referred to as "multi-layered CNTs." As the diameter of carbon nanotubes (CNTs) decreases, they tend to form stronger bundles (bundle structures). This is presumed to be because, as the diameter of CNTs decreases, the specific surface area of ​​the CNTs increases, and furthermore, the flexibility and bendability of the CNTs increase, allowing multiple CNTs to be arranged parallel to each other. As a result of the parallel arrangement and line contact between CNTs, a large contact area is created, and the van der Waals forces between the CNTs become stronger. On the other hand, in multi-walled carbon nanotubes (CNTs), the flexibility and specific surface area of ​​the CNTs decrease as the number of layers and diameter increase, making it difficult to arrange the CNTs parallel to each other in terms of spatial arrangement. As a result, the CNTs cannot make linear contact with each other and instead make point-like contacts that are close to cross contacts. Consequently, the contact area between the CNTs is small, and the van der Waals forces between the CNTs are weakened. Therefore, multiple single-walled carbon nanotubes (SLNTs) are more likely to form bundles than multiple multi-walled carbon nanotubes (SLNTs). The number of CNTs forming a bundle is three or more, preferably four to 100, and more preferably five to 50. Note that, whether single-walled or multi-walled CNTs, there may be CNTs that do not form a bundle.

[0127] The outer diameter of the CNT tube (i.e., the width of the CNT) can be, for example, between 0.8 nm and 400 nm. From the viewpoint of suppressing the occurrence of pellicle film damage, the lower limit of the outer diameter of the CNT tube is preferably 1 nm or more, more preferably 4 nm or more, even more preferably 8 nm or more, very preferably 10 nm or more, and particularly preferably 20 nm or more. From the viewpoint of improving the light transmittance of the pellicle film from EUV light, the upper limit of the outer diameter of the CNT tube is preferably 100 nm or less, more preferably 80 nm or less, even more preferably 60 nm or less, and particularly preferably 40 nm or less. "The outer diameter of the CNT tube" refers to the outer diameter of a single tube when the CNT exists as a single fiber within the pellicle membrane, and to the outer diameter of a single bundle when the CNT exists as a bundle.

[0128] The thickness (outer diameter) of the bundle formed from single-walled carbon nanotubes (hereinafter referred to as "single-walled bundle") may be, for example, 4 nm or more and 400 nm or less. From the viewpoint of suppressing the occurrence of pellicle film damage, the lower limit of the thickness of the single-layer bundle is preferably 10 nm or more, more preferably 20 nm or more, even more preferably 40 nm or more, and particularly preferably 50 nm or more. From the viewpoint of improving the EUV light transmittance of the pellicle film, the upper limit of the thickness of the single-layer bundle is preferably 100 nm or less, more preferably 80 nm or less, even more preferably 60 nm or less, and particularly preferably 40 nm or less.

[0129] The thickness (outer diameter) of the bundle formed from multilayer CNTs (hereinafter referred to as "multilayer bundle") may be, for example, 4 nm or more and 400 nm or less. From the viewpoint of suppressing the occurrence of pellicle film damage, the lower limit of the thickness of the multilayer bundle is preferably 10 nm or more, more preferably 20 nm or more, even more preferably 40 nm or more, and particularly preferably 50 nm or more. From the viewpoint of improving the EUV light transmittance of the pellicle film, the upper limit of the thickness of the multilayer bundle is preferably 100 nm or less, more preferably 80 nm or less, even more preferably 60 nm or less, and particularly preferably 40 nm or less.

[0130] The length of the CNTs is preferably 10 nm or more. Because the CNTs are 10 nm or longer, they interlock well with each other, resulting in excellent mechanical strength of the pellicle film. The upper limit of the CNT length is not particularly limited, but is preferably 10 cm or less, more preferably 1 cm or less, and even more preferably 100 μm or less. From these viewpoints, the length of the CNT is preferably 10 nm to 10 cm, more preferably 10 nm to 1 cm, and even more preferably 10 nm to 100 μm.

[0131] The outer diameter and length of the CNT tubes are determined by the arithmetic mean of values ​​measured for 20 or more carbon materials (primary particles) using electron microscopy. For electron microscopes, scanning electron microscopes (SEMs) and transmission electron microscopes (TEMs) can be used.

[0132] (1.2) Pellicle The pellicle according to the first embodiment comprises a pellicle membrane according to the first embodiment and a pellicle frame. The pellicle membrane is supported by the pellicle frame. The pellicle according to the first embodiment comprises a pellicle film according to the first embodiment, and therefore provides the same effects as the pellicle film according to the first embodiment.

[0133] The pellicle film may or may not be in contact with the pellicle frame. The pellicle frame is a cylindrical object. The pellicle frame has an end face (hereinafter referred to as the "pellicle film end face") on one side in the thickness direction. "The pellicle film is in contact with the pellicle frame" means that the pellicle film is directly fixed to the pellicle film end face. "The pellicle film is not in contact with the pellicle frame" means that the pellicle film is fixed to the pellicle film end face via an adhesive layer. The adhesive is not particularly limited and includes, for example, acrylic resin adhesives, epoxy resin adhesives, polyimide resin adhesives, silicone resin adhesives, inorganic adhesives, double-sided adhesive tapes, polyolefin adhesives, hydrogenated styrene adhesives, etc. The term "adhesive" is a concept that includes not only adhesives but also tackling agents. The thickness of the adhesive layer is not particularly limited and is, for example, 10 μm or more and 1 mm or less.

[0134] (1.2.1) Pellicle frame The pellicle frame has exposure through-holes. These exposure through-holes indicate the spaces through which light transmitted through the pellicle film passes to reach the photomask.

[0135] The shape of the pellicle frame, measured in the thickness direction, is, for example, rectangular. This rectangular shape may be a square or a rectangle.

[0136] The pellicle frame may have ventilation holes. The ventilation holes are formed, for example, on the sides of the pellicle frame. The ventilation holes connect the internal space of the pellicle to the external space of the pellicle when the pellicle frame is attached to the photomask.

[0137] The rectangular pellicle frame, when viewed from the thickness direction, is composed of four sides. The length of one side in the longitudinal direction is preferably 200 mm or less. The size of the pellicle frame is standardized according to the type of exposure equipment. Having a length of 200 mm or less in the longitudinal direction of one side of the pellicle frame satisfies the standardized size for exposure using EUV light. The length of one side in the shorter direction can be, for example, 5 mm to 180 mm, preferably 80 mm to 170 mm, and more preferably 100 mm to 160 mm. The height of the pellicle frame (i.e., the length of the pellicle frame in the thickness direction) is not particularly limited, but is preferably 3.0 mm or less, more preferably 2.4 mm or less, and even more preferably 2.375 mm or less. This ensures that the pellicle frame meets the size standardized for EUV exposure. The height of the pellicle frame standardized for EUV exposure is, for example, 2.375 mm. The mass of the pellicle frame is not particularly limited, but is preferably 20g or less, more preferably 15g or less. This makes the pellicle frame suitable for EUV exposure applications.

[0138] The material of the pellicle frame is not particularly limited and may include quartz glass, metal, carbon-based materials, resin, silicon, and ceramic materials. As the metal, it may be a pure metal or an alloy. A pure metal consists of a single metal element. Examples of pure metals include aluminum, titanium, etc. An alloy consists of a plurality of metal elements or a metal element and a non-metal element. Examples of alloys include stainless steel, magnesium alloy, steel, carbon steel, invar, etc. Examples of resins include polyethylene, etc. Examples of ceramic-based materials include silicon nitride (SiN), silicon carbide (SiC), alumina (Al2O3), etc.

[0139] The structure of the pellicle frame may be a single product or an assembled product. A single product is obtained by cutting out one raw material plate. An "assembled product" is an integrated product of a plurality of members. Methods for integrating a plurality of members include methods using known adhesives, methods using fastening parts, etc. Fastening parts include bolts, nuts, screws, rivets, or pins. When the pellicle frame is an assembled product, the materials of the plurality of members may be different.

[0140] (1.2.2) Adhesive layer The pellicle may further include an adhesive layer. The adhesive layer enables the pellicle to adhere to a photomask. The pellicle frame has an end face (hereinafter referred to as the "end face for photomask") on the other side in the thickness direction. The adhesive layer is formed on the end face for photomask. The adhesive layer is a gel-like soft solid. The adhesive layer preferably has fluidity and cohesive force. "Fluidity" refers to the property of contacting and wetting the photomask as the adherend. "Cohesive force" refers to the property of resisting peeling from the photomask. The adhesive layer consists of an adhesive resin layer. The adhesive layer resin layer is not particularly limited, and examples include acrylic adhesives, silicone adhesives, styrene adhesives, urethane adhesives, olefin adhesives, etc. The thickness of the adhesive layer is not particularly limited, and is preferably 10 μm to 500 μm.

[0141] (1.3) Exposure original The exposure original plate according to the first embodiment includes a photomask and a pellicle according to the first embodiment. The photomask is an original plate having a circuit pattern. The pellicle is attached to the photomask on the surface where the circuit pattern is formed. Since the exposure original plate according to the first embodiment includes the pellicle according to the first embodiment, it exhibits the same effects as the pellicle according to the first embodiment.

[0142] The method of attaching the photomask to the pellicle (hereinafter referred to as the "attachment method") is not particularly limited, and examples include the method using the above-described adhesive layer, the method using fastening parts, and the method using the attraction force of a magnet or the like.

[0143] The photomask has a support substrate, a reflective layer, and an absorber layer. The support substrate, the reflective layer, and the absorber layer are preferably laminated in this order. In this case, the pellicle is attached to the side of the photomask where the reflective layer and the absorber layer are provided. By the absorber layer partially absorbing EUV light, a desired image is formed on a sensitive substrate (for example, a semiconductor substrate with a photoresist film). Examples of the reflective layer include a multilayer film of molybdenum (Mo) and silicon (Si). The material of the absorber layer may be a material with high absorption of EUV or the like. Examples of materials with high absorption of EUV or the like include chromium (Cr), tantalum nitride, and the like.

[0144] (1.4) Exposure apparatus The exposure apparatus according to the first embodiment includes an EUV light source, an exposure original plate according to the first embodiment, and an optical system. The EUV light source emits EUV light as exposure light. The optical system guides the exposure light emitted from the EUV light source to the exposure original plate. The exposure original plate is arranged such that the exposure light emitted from the EUV light source passes through the pellicle film and irradiates the photomask. Therefore, the exposure apparatus according to the first embodiment exhibits the same effects as the exposure original plate according to the first embodiment. Furthermore, since the exposure apparatus according to the first embodiment has the above-described configuration, in addition to being able to form a miniaturized pattern (for example, a line width of 32 nm or less), it is possible to perform pattern exposure with reduced resolution failure due to foreign matter.

[0145] A known EUV light source can be used. A known optical system can be used.

[0146] (1.5) Method for manufacturing pellicle film The method for manufacturing a pellicle film according to the first embodiment is a method for manufacturing a pellicle film according to the first embodiment, and includes a coating step. In the coating step, a dispersion liquid containing a plurality of CNTs synthesized by a direct injection pyrolysis synthesis method (hereinafter referred to as the "eDIPS method") (hereinafter referred to as the "CNT dispersion liquid") is coated onto a substrate.

[0147] The method for manufacturing a pellicle film according to the first embodiment has the above configuration, and therefore a pellicle film can be obtained in which the average value of the linearity parameters of the multiple CNTs is 0.10 or less. This is presumed to be mainly due to the fact that each of the multiple CNTs synthesized by the eDIPS method is linear and has a low structural defect density. CNTs synthesized by methods other than eDIPS may also be used, as long as they are linear and have a low structural defect density.

[0148] The method for manufacturing a pellicle film according to the first embodiment preferably includes, in addition to the coating step, a preparation step, a dispersion preparation step, a washing step, and a separation step, which will be described later. When the method for manufacturing a pellicle film includes a preparation step, a dispersion preparation step, a coating step, a washing step, and a separation step, the preparation step, the dispersion preparation step, the coating step, the washing step, and the separation step are performed in this order. The following describes a case in which the method for manufacturing a pellicle film according to the first embodiment includes, in addition to the coating step, a preparation step, a dispersion preparation step, a washing step, and a separation step, which will be described later.

[0149] (1.5.1) Preparation process In the preparation step, multiple CNTs synthesized by the direct injection pyrolysis synthesis method (hereinafter referred to as the "eDIPS method") are prepared.

[0150] The e-DIPS (Enhanced Direct Injection Pyrolytic Synthesis) method is a gas-phase flow method that is an improved version of the Direct Injection Pyrolytic Synthesis method (hereinafter referred to as the "DIPS method"). In the DIPS method, a hydrocarbon-based solution containing a catalyst (or catalyst precursor) and a reaction accelerator is atomized by spraying and introduced into a high-temperature heating furnace to synthesize single-walled carbon nanotubes (WYNTs) in a flowing gas phase. The e-DIPS method focuses on the particle formation process in which ferrocene, used as a catalyst, has different particle sizes upstream and downstream in the reactor. Unlike the DIPS method, which has used only organic solvents as a carbon source, e-DIPS is relatively easily decomposed in the carrier gas. In other words, it is a method that controls the growth point of single-walled carbon nanotubes by mixing in a second carbon source that is more readily used as a carbon source. For details, refer to Saito et al., J. Nanosci. Nanotechnol., 8(2008) 6153-6157 for manufacturing instructions.

[0151] Multiple CNTs synthesized by the e-DIPS method include single-walled CNTs. e-DIPS method CNTs may include single-layer CNTs, as well as two-layer or three-layer CNTs, or two-layer and three-layer CNTs.

[0152] Methods for preparing multiple CNTs synthesized by the e-DIPS method include, for example, a method of synthesizing multiple CNTs by the e-DIPS method, or a method of using commercially available multiple CNTs synthesized by the e-DIPS method. Examples of commercially available carbon nanotubes synthesized by the e-DIPS method include "MEIJOeDIPS" manufactured by Meijo Nanocarbon Co., Ltd.

[0153] (1.5.2) Dispersion liquid preparation process In the dispersion preparation step, a plurality of CNTs synthesized by the e-DIPS method, a dispersant, and a solvent are mixed to prepare a dispersion. A part of the plurality of CNTs synthesized by the e-DIPS method forms a plurality of bundles. Thereby, a dispersion in which a plurality of bundles are dispersed is obtained.

[0154] The dispersant is not particularly limited, and examples thereof include polyacrylic acid, flavin derivatives, sodium cholate, sodium deoxycholate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium polyacrylate, organic side-chain flavin, and the like. The addition amount of the dispersant is not particularly limited, and is preferably 10 parts by mass or more and 1000 parts by mass or less, more preferably 30 parts by mass or more and 500 parts by mass or less, based on the total amount of the plurality of CNTs synthesized by the e-DIPS method.

[0155] The solvent is not particularly limited and is appropriately selected according to the type of the dispersant and the like. Examples thereof include isopropyl alcohol, ethanol, toluene, xylene, ethylbenzene, n-methylpyrrolidone, N,N-dimethylformamide, propylene glycol, methyl isobutyl ketone, and the like. The addition amount of the solvent is preferably 0.005 parts by mass or more and 1 part by mass or less, more preferably 0.01 parts by mass or more and 0.1 part by mass or less, based on the total amount of the dispersion.

[0156] The method of mixing a plurality of CNTs synthesized by the e-DIPS method, a dispersant, and a solvent is not particularly limited, and examples thereof include a method using cavitation (ultrasonic dispersion method), a method of mechanically applying a shearing force (magnetic stirrer, ball mill, roller mill, vibration mill, kneader, homogenizer, etc.), and a method using turbulent flow (jet mill, nanomizer, etc.).

[0157] To minimize damage to the CNTs, it is preferable to reduce the force applied to the CNTs when mixing multiple CNTs, a dispersant, and a solvent, or when performing ultracentrifugation. For example, it is preferable to shorten the mixing time when mixing multiple CNTs, a dispersant, and a solvent. The mixing time in the dispersion preparation step is preferably less than 1 hour, more preferably 40 minutes or less.

[0158] (1.5.3) Coating process In the coating process, a CNT dispersion is applied to the substrate. This results in a coating film on the substrate containing multiple CNTs synthesized by the e-DIPS method.

[0159] The shape of the substrate is not particularly limited and can be circular, rectangular, or the like. The substrate thickness is preferably 100 μm or more and 1000 μm or less, and more preferably 200 μm or more and 1000 μm or less from the viewpoint of handling. The substrate roughness Ra is not particularly limited, but can be, for example, 10 μm or less. To improve the uniformity of the pellicle film, the substrate roughness Ra is preferably 100 nm or less, more preferably 10 nm or less, and particularly preferably 1 nm or less. The substrate material is not particularly limited and can include semiconductor materials, glass materials, ceramic materials, filter paper, etc. Examples of semiconductor materials include silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), and gallium arsenide (GaAs). Examples of glass materials include quartz glass (silicon oxide (SiO2)), soda glass, borosilicate glass, and sapphire. Examples of ceramic materials include silicon nitride (SiN), aluminum nitride (AlN) substrates, zirconia (ZrO2) substrates, and aluminum oxide (Al2O3). If the substrate is filter paper, a method may be used in which a CNT film is formed on the filter paper by dropping the CNT dispersion onto the filter paper and removing the solvent.

[0160] The method for applying the CNT dispersion to the substrate is not particularly limited and includes, for example, spin coating, dip coating, bar coating, spray coating, electrospray coating, etc.

[0161] (1.5.4) Washing process In the cleaning step, the coating film obtained in the coating step is cleaned. This results in a pellicle film from which the dispersant contained in the coating film has been removed. Depending on the cleaning method of the coating film, a pellicle film is obtained in which the average value of the packing density parameters of the multiple bundles described above is adjusted to a desired range.

[0162] The cleaning method is not particularly limited and includes alkaline cleaning and water washing. Alkaline cleaning refers to contacting the coated film with an alkaline solution. Water washing refers to contacting the coated film with water. In order to reduce the amount of residual solution components and make it easier to obtain a pellicle film with an average value of the CNT packing density parameter that is closer to zero, it is preferable to use a solution and / or solvent with high solubility for the CNT dispersant in the washing method. A highly soluble solution and / or solvent may be appropriately selected depending on the type of dispersant. When the molecular skeleton of a dispersant has bonds with a large difference in electronegativity (i.e., the molecular skeleton of the dispersant consists of a highly polar molecular skeleton), it is preferable to use a polar solvent as the washing solution. Examples of highly polar dispersants include polyethylene glycol, and suitable washing solutions for this dispersant include water and ethanol. When the molecular skeleton of a dispersant has bonds with a small difference in electronegativity (i.e., when the molecular skeleton of the dispersant includes a molecular skeleton with low polarity), it is preferable to use a solvent with low polarity as the washing solution. Examples of dispersants with low polarity include organic side-chain flavins, and suitable washing solutions for washing these dispersants include chloroform and toluene. When the dispersant contains an ionic cationic solution, it is preferable to use an acidic solution as the washing solution. Examples of ionic cationic dispersants include dodecyltrimethylammonium chloride, and suitable washing solutions for this dispersant include water and acidic aqueous solutions. When the dispersant contains an ionic solution, it is preferable to use an alkaline solution as the washing solution. Examples of anionic dispersants include polyacrylic acid and sodium polyacrylate, and suitable washing solutions for these dispersants include water and alkaline solutions. In particular, the preferred washing method involves alkaline washing of a dispersion solution of polyacrylic acid. This results in a pellicle film in which the average value of the packing density parameters of multiple bundles is closer to zero than when washed with water.

[0163] The alkaline solution preferably contains a basic compound. Examples of basic compounds include ammonia, quaternary ammonium hydroxide, and quaternary pyridinium hydroxide. Examples of quaternary ammonium hydroxides include tetramethylammonium hydroxide (TMAH) and choline.

[0164] (1.5.5) Separation process In the separation process, the pellicle film is separated from the substrate. This yields a single pellicle film.

[0165] Hereinafter, the substrate and the pellicle film formed on the substrate will be collectively referred to as a "film-coated substrate."

[0166] The method for separating the pellicle film from the substrate is not particularly limited, but one method is to immerse the film-coated substrate in water. When the film-coated substrate is immersed in water, the pellicle film peels off from the substrate and floats on the water surface. This yields a separate pellicle film.

[0167] (2) First modified example (packing density parameter) (2.1) Pellicle membrane The pellicle film according to the first modified example includes a plurality of CNTs. At least a portion of the plurality of CNTs form a plurality of bundles, and the average value of the packing density parameter of the plurality of bundles represented by formula (2) above may be 0.20 or less. In the first modified example, since the pellicle film has the above-described structure, it is less prone to film reduction even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment.

[0168] The pellicle according to the first modified example is the same as the pellicle according to the first embodiment, except that the average value of the packing density parameter is 0.20 or less, and the average value of the linearity parameter represented by formula (1) above is not required to be 0.10 or less. The description of the first modified example in this disclosure can be made by reference to the description of the first embodiment in this disclosure.

[0169] The packing density parameters, the preferred range of the average value of the packing density parameters, and the method for measuring the packing density parameters are the same as in the first embodiment.

[0170] In the first modified example, it is preferable that the average value of the packing density parameters of the multiple bundles is 0.15 or less. If the average value of the packing density parameters of multiple bundles is 0.15 or less, the loss of the pellicle film can be further suppressed even when exposed to hydrogen plasma.

[0171] In the first modified example, it is preferable that the average value of the linearity parameter of the plurality of CNTs represented by the above formula (1) is 0.10 or less. If the average value of the linearity parameters of multiple CNTs is 0.10 or less, the film will be less prone to thinning even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment. The linearity parameter, the preferred range of the mean value of the linearity parameter, and the method for measuring the linearity parameter are the same as in the first embodiment.

[0172] In the first modified example, the pellicle film preferably contains a plurality of carbon nanotubes forming a bundle, and the second diffraction peak ratio is 1.3 or higher. If the second diffraction peak ratio is within the above range, the diffusion of hydrogen radicals into the single bundle is further suppressed. As a result, the pellicle film exhibits higher lifetime characteristics and is less prone to film degradation even when exposed to hydrogen plasma. The second diffraction peak ratio, the preferred range of the second diffraction peak ratio, and the method for measuring the second diffraction peak are the same as in the first embodiment.

[0173] In the first modified example, the pellicle film contains a plurality of carbon nanotubes forming a bundle, and the smoothness evaluation value is 0.070 (nm). 2 It is preferable that it is less than or equal to / nm. If the smoothness evaluation value is within the range described above, the loss of the pellicle film can be suppressed even when the pellicle film is exposed to hydrogen plasma. The smoothness evaluation value, the preferred range of the smoothness evaluation value, and the method for measuring the smoothness evaluation value are the same as in the first embodiment.

[0174] In the first modified example, a bundle containing multiple carbon nanotubes (CNTs) is included. It is preferable that the ratio (G / D) is 0.8 or higher. If the ratio (G / D) is within the above range, the etching reaction of CNTs will not proceed easily when CNTs react with hydrogen plasma and CNTs are etched. The ratio (G / D), the preferred range of the ratio (G / D), and the method for measuring the ratio (G / D) are the same as in the first embodiment.

[0175] The first diffraction peak ratio, the average value of the gap area ratio, the first lifetime evaluation method for the pellicle film, and the first lifetime evaluation method for the pellicle film are the same as in the first embodiment.

[0176] In the first modified example, the structure of the pellicle film, the thickness of the pellicle film, and the CNTs are the same as in the first embodiment. In the first modified example, the pellicle film may comprise other layers, similar to the first embodiment.

[0177] (2.2) Pellicle The pellicle according to the first modified example comprises a pellicle membrane according to the first modified example and a pellicle frame. The pellicle membrane is supported by the pellicle frame. The pellicle according to the first modified example comprises a pellicle film according to the first modified example, and therefore produces the same effect as the pellicle film according to the first modified example. In the first modification, the pellicle may further comprise an adhesive layer. The pellicle frame and adhesive layer, etc., are the same as in the first embodiment.

[0178] (2.3) Exposure master plate The exposure master according to the first modification comprises a photomask and a pellicle according to the first modification. The photomask is a master having a circuit pattern. The pellicle is attached to the surface on which the circuit pattern is formed on the photomask. The exposure master plate according to the first modified example is equipped with a pellicle according to the first modified example, and therefore produces the same effect as the pellicle according to the first modified example. The mounting method and the photomask, etc., are the same as in the first embodiment.

[0179] (2.4) Exposure apparatus The exposure apparatus according to the first modified example comprises an EUV light source, an exposure master according to the first modified example, and an optical system. The EUV light source emits EUV light as exposure light. The optical system guides the exposure light emitted from the EUV light source to the exposure master. The exposure master is positioned so that the exposure light emitted from the EUV light source passes through a pellicle film and irradiates the photomask. Therefore, the exposure apparatus according to the first modified example produces the same effect as the exposure master plate according to the first modified example. Furthermore, because the exposure apparatus according to the first modified example has the above configuration, it can form finely detailed patterns (for example, with a line width of 32 nm or less), and can perform pattern exposure with reduced resolution defects due to foreign matter. A known EUV light source can be used. A known optical system can be used.

[0180] (2.5) Method for manufacturing pellicle film The method for manufacturing a pellicle film according to the first modified example is a method for manufacturing a pellicle film according to the first modified example, and includes a coating step. In the coating step, a dispersion liquid containing a plurality of CNTs synthesized by direct injection pyrolysis synthesis is applied to a substrate. The method for manufacturing a pellicle film according to the first modified example has the above configuration, and therefore a pellicle film with an average value of packing density parameters of 0.20 or less can be obtained. In the first modified example, the method for manufacturing the pellicle film preferably includes a preparation step, a dispersion preparation step, a washing step, and a separation step, in addition to the coating step. The coating step, preparation step, dispersion preparation step, washing step, and separation step are the same as in the first embodiment.

[0181] In the first modified example, the method for manufacturing the pellicle film preferably further includes a cleaning step of alkaline cleaning the coated film obtained in the coating step. This results in a pellicle film from which the dispersant contained in the coated film has been removed.

[0182] (3) Second variation (ratio of first diffraction peak) (3.1) Pellicle membrane The pellicle film according to the second modified example contains a plurality of CNTs, the plurality of CNTs forming a bundle, and the first diffraction peak ratio may be 2 or more. In the second modified example, since the pellicle film has the above-described structure, it is less prone to film reduction even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment.

[0183] The pellicle according to the second modification is the same as the pellicle according to the first embodiment, except that the first diffraction peak ratio is 2 or more, and the average value of the linearity parameter represented by formula (1) above is not required to be 0.10 or less. The description of the second modification of this disclosure can be made by reference to the description of the first embodiment of this disclosure.

[0184] In the second modified example, the first diffraction peak ratio, the preferred range of the first diffraction peak ratio, and the method for measuring the first diffraction peak ratio are the same as in the first embodiment.

[0185] In the second modified example, it is preferable that the average value of the linearity parameter expressed by equation (1) above for multiple CNTs is 0.10 or less. If the average value of the linearity parameters of multiple CNTs is 0.10 or less, the film will be less prone to thinning even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment. The linearity parameter, the preferred range of the mean value of the linearity parameter, and the method for measuring the linearity parameter are the same as in the first embodiment.

[0186] In the second modified example, the multiple CNTs form multiple bundles, and the average value of the packing density parameters of the multiple bundles, as expressed by formula (2) above, may be 0.20 or less. In the second modified example, since the pellicle film has the above-described structure, it is less prone to film reduction even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment. The packing density parameters, the preferred range of the average value of the packing density parameters, and the method for measuring the packing density parameters are the same as in the first embodiment.

[0187] In the second modified example, it is preferable that the average value of the packing density parameters of the multiple bundles is 0.15 or less. If the average value of the packing density parameters of multiple bundles is 0.15 or less, the loss of the pellicle film can be further suppressed even when exposed to hydrogen plasma.

[0188] In the second modified example, the pellicle film preferably contains multiple carbon nanotubes forming a bundle, and the second diffraction peak ratio is 1.3 or higher. If the second diffraction peak ratio is within the above range, the diffusion of hydrogen radicals into the single bundle is further suppressed. As a result, the pellicle film exhibits higher lifetime characteristics and is less prone to film degradation even when exposed to hydrogen plasma. The second diffraction peak ratio, the preferred range of the second diffraction peak ratio, and the method for measuring the second diffraction peak are the same as in the first embodiment.

[0189] In the second modified example, the pellicle film contains multiple carbon nanotubes forming a bundle, and the smoothness evaluation value is 0.070 (nm). 2 It is preferable that it is less than or equal to / nm. If the smoothness evaluation value is within the range described above, the loss of the pellicle film can be suppressed even when the pellicle film is exposed to hydrogen plasma. The smoothness evaluation value, the preferred range of the smoothness evaluation value, and the method for measuring the smoothness evaluation value are the same as in the first embodiment.

[0190] In the second modified example, a bundle containing multiple carbon nanotubes (CNTs) is included. It is preferable that the ratio (G / D) is 0.8 or higher. If the ratio (G / D) is within the above range, the etching reaction of CNTs will not proceed easily when CNTs react with hydrogen plasma and CNTs are etched. The ratio (G / D), the preferred range of the ratio (G / D), and the method for measuring the ratio (G / D) are the same as in the first embodiment.

[0191] The first diffraction peak ratio, the average value of the gap area ratio, the first lifetime evaluation method for the pellicle film, and the first lifetime evaluation method for the pellicle film are the same as in the first embodiment.

[0192] In the second modified example, the structure of the pellicle film, the thickness of the pellicle film, and the CNTs are the same as in the first embodiment. In the second modified example, the pellicle film may comprise other layers, similar to the first embodiment.

[0193] (3.2) Pellicle The pellicle according to the second modified example comprises a pellicle membrane according to the second modified example and a pellicle frame. The pellicle membrane is supported by the pellicle frame. The pellicle according to the second modified example comprises a pellicle film according to the second modified example, and therefore produces the same effect as the pellicle film according to the second modified example. In the second modification, the pellicle may further comprise an adhesive layer. The pellicle frame and adhesive layer are the same as in the first embodiment.

[0194] (3.3) Exposure master plate The exposure master according to the second modification comprises a photomask and a pellicle according to the second modification. The photomask is a master having a circuit pattern. The pellicle is attached to the surface on which the circuit pattern is formed on the photomask. The exposure master plate according to the second modified example is equipped with a pellicle according to the second modified example, and therefore produces the same effect as the pellicle according to the second modified example. The mounting method and the photomask, etc., are the same as in the first embodiment.

[0195] (3.4) Exposure apparatus The exposure apparatus according to the second modification comprises an EUV light source, an exposure master according to the second modification, and an optical system. The EUV light source emits EUV light as exposure light. The optical system guides the exposure light emitted from the EUV light source to the exposure master. The exposure master is positioned so that the exposure light emitted from the EUV light source passes through the pellicle film and irradiates the photomask. Therefore, the exposure apparatus according to the second modified example produces the same effect as the exposure master plate according to the second modified example. Furthermore, because the exposure apparatus according to the second modified example has the above configuration, it can form finely detailed patterns (for example, line width of 32 nm or less), and can perform pattern exposure with reduced resolution defects due to foreign matter. A known EUV light source can be used. A known optical system can be used.

[0196] (3.5) Method for manufacturing pellicle film The method for manufacturing a pellicle film according to the second modified example is a method for manufacturing a pellicle film according to the second modified example, and includes a coating step. In the coating step, a dispersion liquid containing a plurality of CNTs synthesized by direct injection pyrolysis synthesis is applied to a substrate. The method for manufacturing a pellicle film according to the second modified example has the above configuration, and therefore a pellicle film with a first diffraction peak ratio of 2 or more can be obtained. In the second modified example, the method for manufacturing the pellicle film preferably includes a preparation step, a dispersion preparation step, a washing step, and a separation step, in addition to the coating step. The coating step, preparation step, dispersion preparation step, washing step, and separation step are the same as in the first embodiment.

[0197] In a second modification, the method for manufacturing the pellicle film preferably further includes a cleaning step of alkaline cleaning the coated film obtained in the coating step. This results in a pellicle film from which the dispersant contained in the coated film has been removed.

[0198] (4) Third variation (second diffraction peak ratio) (4.1) Pellicle membrane The pellicle film according to the third modified example may contain multiple CNTs forming a bundle, and the second diffraction peak ratio may be 1.3 or higher. In the third modified example, the pellicle film has the above-described structure, so it is less prone to film reduction even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment.

[0199] The pellicle according to the third modification is the same as the pellicle according to the first embodiment, except that the second diffraction peak ratio is 1.3 or higher, and the average value of the linearity parameter represented by formula (1) above is not required to be 0.10 or lower. The description of the third modification of this disclosure can be made by reference to the description of the first embodiment of this disclosure.

[0200] The second diffraction peak ratio, the preferred range of the second diffraction peak ratio, and the method for measuring the second diffraction peak ratio are the same as in the first embodiment.

[0201] In the third modified example, it is preferable that the average value of the linearity parameter expressed by the above formula (1) for multiple CNTs is 0.10 or less. If the average value of the linearity parameters of multiple CNTs is 0.10 or less, the film will be less prone to thinning even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment. The linearity parameter, the preferred range of the mean value of the linearity parameter, and the method for measuring the linearity parameter are the same as in the first embodiment.

[0202] In the third modified example, the multiple CNTs form multiple bundles, and the average value of the packing density parameters of the multiple bundles, as expressed by formula (2) above, may be 0.20 or less. In the third modified example, the pellicle film has the above-described structure, so it is less prone to film reduction even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment. The packing density parameters, the preferred range of the average value of the packing density parameters, and the method for measuring the packing density parameters are the same as in the first embodiment.

[0203] In the third modified example, it is preferable that the average value of the packing density parameters of the multiple bundles is 0.15 or less. If the average value of the packing density parameters of multiple bundles is 0.15 or less, the loss of the pellicle film can be further suppressed even when exposed to hydrogen plasma.

[0204] In the third modified example, the pellicle film contains multiple carbon nanotubes forming a bundle, and the smoothness evaluation value is 0.070 (nm). 2 It is preferable that it is less than or equal to / nm. If the smoothness evaluation value is within the range described above, the loss of the pellicle film can be suppressed even when the pellicle film is exposed to hydrogen plasma. The smoothness evaluation value, the preferred range of the smoothness evaluation value, and the method for measuring the smoothness evaluation value are the same as in the first embodiment.

[0205] In the third modification, a bundle containing multiple carbon nanotubes (CNTs) is included. It is preferable that the ratio (G / D) is 0.8 or higher. If the ratio (G / D) is within the above range, the etching reaction of CNTs will not proceed easily when CNTs react with hydrogen plasma and CNTs are etched. The ratio (G / D), the preferred range of the ratio (G / D), and the method for measuring the ratio (G / D) are the same as in the first embodiment.

[0206] The first diffraction peak ratio, the average value of the gap area ratio, the first lifetime evaluation method for the pellicle film, and the first lifetime evaluation method for the pellicle film are the same as in the first embodiment.

[0207] In the third modified example, the structure of the pellicle film, the thickness of the pellicle film, and the CNTs are the same as in the first embodiment. In the third modification, the pellicle film may comprise other layers, similar to the first embodiment.

[0208] (4.2) Pellicle The pellicle according to the third modified example comprises a pellicle membrane according to the third modified example and a pellicle frame. The pellicle membrane is supported by the pellicle frame. The pellicle according to the third modified example comprises a pellicle film according to the third modified example, and therefore produces the same effect as the pellicle film according to the third modified example. In the third modification, the pellicle may further comprise an adhesive layer. The pellicle frame and adhesive layer, etc., are the same as in the first embodiment.

[0209] (4.3) Exposure master plate The exposure master according to the third modification comprises a photomask and a pellicle according to the third modification. The photomask is a master having a circuit pattern. The pellicle is attached to the surface on which the circuit pattern is formed on the photomask. The exposure master according to the third modified example is equipped with a pellicle according to the third modified example, and therefore produces the same effect as the pellicle according to the third modified example. The mounting method and the photomask, etc., are the same as in the first embodiment.

[0210] (4.4) Exposure apparatus The exposure apparatus according to the third modification comprises an EUV light source, an exposure master according to the third modification, and an optical system. The EUV light source emits EUV light as exposure light. The optical system guides the exposure light emitted from the EUV light source to the exposure master. The exposure master is positioned so that the exposure light emitted from the EUV light source passes through the pellicle film and irradiates the photomask. Therefore, the exposure apparatus according to the third modified example achieves the same effect as the exposure master plate according to the third modified example. Furthermore, because the exposure apparatus according to the third modified example has the above configuration, it can form finely detailed patterns (for example, with a line width of 32 nm or less), and can also perform pattern exposure with reduced resolution defects due to foreign matter. A known EUV light source can be used. A known optical system can be used.

[0211] (4.5) Method for manufacturing pellicle membrane The method for manufacturing a pellicle film according to the third modified example is a method for manufacturing a pellicle film according to the third modified example, and includes a coating step. In the coating step, a dispersion liquid containing a plurality of CNTs synthesized by direct injection pyrolysis synthesis is applied to a substrate. The method for manufacturing a pellicle film according to the third modified example has the above configuration, and therefore a pellicle film with a second diffraction peak ratio of 1.3 or higher can be obtained. In the third modified example, the method for manufacturing the pellicle film preferably includes a preparation step, a dispersion preparation step, a washing step, and a separation step, in addition to the coating step. The coating step, preparation step, dispersion preparation step, washing step, and separation step are the same as in the first embodiment.

[0212] In the third modified example, the method for manufacturing the pellicle film preferably further includes a cleaning step of alkaline cleaning the coated film obtained in the coating step. This results in a pellicle film from which the dispersant contained in the coated film has been removed.

[0213] (5) Fourth modified example (smoothness evaluation value) (5.1) Pellicle membrane The pellicle film according to the fourth modified example includes a plurality of CNTs forming a bundle, and the smoothness evaluation value may be 0.070 nm or less. In the fourth modified example, since the pellicle film has the above-described structure, it is less prone to film reduction even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment.

[0214] The pellicle according to the fourth modification is the same as the pellicle according to the first embodiment, except that it does not need to have a smoothness evaluation value of 0.070 nm or less and the average value of the linearity parameter represented by formula (1) above be 0.10 or less. The description of the fourth modification of this disclosure can be made by reference to the description of the first embodiment of this disclosure.

[0215] The smoothness evaluation value, the preferred range of the smoothness evaluation value, and the method for measuring the smoothness evaluation value are the same as in the first embodiment.

[0216] In the fourth modified example, it is preferable that the average value of the linearity parameter expressed by the above formula (1) for multiple CNTs is 0.10 or less. If the average value of the linearity parameters of multiple CNTs is 0.10 or less, the film will be less prone to thinning even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment. The linearity parameter, the preferred range of the mean value of the linearity parameter, and the method for measuring the linearity parameter are the same as in the first embodiment.

[0217] In the fourth modified example, the multiple CNTs form multiple bundles, and the average value of the packing density parameters of the multiple bundles, as expressed by formula (2) above, may be 0.20 or less. In the fourth modified example, since the pellicle film has the above-described structure, it is less prone to film reduction even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment. The packing density parameters, the preferred range of the average value of the packing density parameters, and the method for measuring the packing density parameters are the same as in the first embodiment.

[0218] In the fourth modified example, it is preferable that the average value of the packing density parameters of the multiple bundles is 0.15 or less. If the average value of the packing density parameters of multiple bundles is 0.15 or less, the loss of the pellicle film can be further suppressed even when exposed to hydrogen plasma.

[0219] In the fourth modified example, the pellicle film preferably contains a plurality of carbon nanotubes forming a bundle, and the second diffraction peak ratio is 1.3 or higher. If the second diffraction peak ratio is within the above range, the diffusion of hydrogen radicals into the single bundle is further suppressed. As a result, the pellicle film exhibits higher lifetime characteristics and is less prone to film degradation even when exposed to hydrogen plasma. The second diffraction peak ratio, the preferred range of the second diffraction peak ratio, and the method for measuring the second diffraction peak are the same as in the first embodiment.

[0220] In the fourth modified example, a bundle containing multiple carbon nanotubes (CNTs) is included. It is preferable that the ratio (G / D) is 0.8 or higher. If the ratio (G / D) is within the above range, the etching reaction of CNTs will not proceed easily when CNTs react with hydrogen plasma and CNTs are etched. The ratio (G / D), the preferred range of the ratio (G / D), and the method for measuring the ratio (G / D) are the same as in the first embodiment.

[0221] The first diffraction peak ratio, the average value of the gap area ratio, the first lifetime evaluation method for the pellicle film, and the first lifetime evaluation method for the pellicle film are the same as in the first embodiment.

[0222] In the fourth modified example, the structure of the pellicle film, the thickness of the pellicle film, and the CNTs are the same as in the first embodiment. In the fourth modified example, the pellicle film may comprise other layers, similar to the first embodiment.

[0223] (5.2) Pellicle The pellicle according to the fourth modification comprises a pellicle membrane according to the fourth modification and a pellicle frame. The pellicle membrane is supported by the pellicle frame. The pellicle according to the fourth modified example comprises a pellicle film according to the fourth modified example, and therefore produces the same effect as the pellicle film according to the fourth modified example. In the fourth modification, the pellicle may further comprise an adhesive layer. The pellicle frame and adhesive layer are the same as in the first embodiment.

[0224] (5.3) Exposure master plate The exposure master according to the fourth modification comprises a photomask and a pellicle according to the fourth modification. The photomask is a master having a circuit pattern. The pellicle is attached to the surface on which the circuit pattern is formed on the photomask. The exposure master according to the fourth modified example is equipped with a pellicle according to the fourth modified example, and therefore produces the same effect as the pellicle according to the fourth modified example. The mounting method and the photomask, etc., are the same as in the first embodiment.

[0225] (5.4) Exposure apparatus The exposure apparatus according to the fourth modification comprises an EUV light source, an exposure master according to the fourth modification, and an optical system. The EUV light source emits EUV light as exposure light. The optical system guides the exposure light emitted from the EUV light source to the exposure master. The exposure master is positioned so that the exposure light emitted from the EUV light source passes through the pellicle film and irradiates the photomask. Therefore, the exposure apparatus according to the fourth modified example achieves the same effect as the exposure master plate according to the fourth modified example. Furthermore, because the exposure apparatus according to the fourth modified example has the above configuration, it can form finely detailed patterns (for example, with a line width of 32 nm or less), and can also perform pattern exposure with reduced resolution defects due to foreign matter. A known EUV light source can be used. A known optical system can be used.

[0226] (5.5) Method for manufacturing pellicle membrane The method for manufacturing a pellicle film according to the fourth modified example is a method for manufacturing a pellicle film according to the fourth modified example, and includes a coating step. In the coating step, a dispersion liquid containing a plurality of CNTs synthesized by direct injection pyrolysis synthesis is applied to a substrate. The method for manufacturing a pellicle film according to the fourth modified example has the above configuration, and therefore a pellicle film with a smoothness evaluation value of 0.070 nm or less can be obtained. In the fourth modified example, the method for manufacturing the pellicle film preferably includes a preparation step, a dispersion preparation step, a washing step, and a separation step, in addition to the coating step. The coating step, preparation step, dispersion preparation step, washing step, and separation step are the same as in the first embodiment.

[0227] In the fourth modified example, the method for manufacturing the pellicle film preferably further includes a cleaning step of alkaline cleaning the coated film obtained in the coating step. This results in a pellicle film from which the dispersant contained in the coated film has been removed.

[0228] (6) Fifth variation (average value of the percentage of gap area) (6.1) Pellicle membrane The pellicle film according to the fifth modified example contains a plurality of CNTs, the plurality of CNTs forming a bundle, and the average value of the ratio of the gap area may be 30% or less. In the fifth modified example, the pellicle film has the above-described structure, and therefore is less prone to film reduction even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment.

[0229] The pellicle according to the fifth modified example is the same as the pellicle according to the first embodiment, except that the average value of the ratio of gap areas is 30% or less, and the average value of the linearity parameter represented by formula (1) above is not required to be 0.10 or less. The description of the fifth modified example of this disclosure can be made by reference to the description of the first embodiment of this disclosure.

[0230] The ratio of the gap area, the preferred range of the ratio of the gap area, and the method for measuring the ratio of the gap area are the same as in the first embodiment.

[0231] In the fifth modified example, it is preferable that the average value of the linearity parameter expressed by the above formula (1) for multiple CNTs is 0.10 or less. If the average value of the linearity parameters of multiple CNTs is 0.10 or less, the film will be less prone to thinning even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment. The linearity parameter, the preferred range of the mean value of the linearity parameter, and the method for measuring the linearity parameter are the same as in the first embodiment.

[0232] In the fifth modified example, the multiple CNTs form multiple bundles, and the average value of the packing density parameters of the multiple bundles, as expressed by formula (2) above, may be 0.20 or less. In the fifth modified example, the pellicle film has the above-described structure, and therefore is less prone to film reduction even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment. The packing density parameters, the preferred range of the average value of the packing density parameters, and the method for measuring the packing density parameters are the same as in the first embodiment.

[0233] In the fifth modified example, it is preferable that the average value of the packing density parameters of the multiple bundles is 0.15 or less. If the average value of the packing density parameters of multiple bundles is 0.15 or less, the loss of the pellicle film can be further suppressed even when exposed to hydrogen plasma.

[0234] In the fifth modification, the pellicle film preferably contains a plurality of carbon nanotubes forming a bundle, and the second diffraction peak ratio is 1.3 or higher. If the second diffraction peak ratio is within the above range, the diffusion of hydrogen radicals into the single bundle is further suppressed. As a result, the pellicle film exhibits higher lifetime characteristics and is less prone to film degradation even when exposed to hydrogen plasma. The second diffraction peak ratio, the preferred range of the second diffraction peak ratio, and the method for measuring the second diffraction peak are the same as in the first embodiment.

[0235] In the fifth modified example, the pellicle film contains multiple carbon nanotubes forming a bundle, and the smoothness evaluation value is 0.070 (nm). 2 It is preferable that it is less than or equal to / nm. If the smoothness evaluation value is within the range described above, the loss of the pellicle film can be suppressed even when the pellicle film is exposed to hydrogen plasma. The smoothness evaluation value, the preferred range of the smoothness evaluation value, and the method for measuring the smoothness evaluation value are the same as in the first embodiment.

[0236] In the fifth variation, a bundle containing multiple carbon nanotubes (CNTs) is included. It is preferable that the ratio (G / D) is 0.8 or higher. If the ratio (G / D) is within the above range, the etching reaction of CNTs will not proceed easily when CNTs react with hydrogen plasma and CNTs are etched. The ratio (G / D), the preferred range of the ratio (G / D), and the method for measuring the ratio (G / D) are the same as in the first embodiment.

[0237] The first diffraction peak ratio, the average value of the gap area ratio, the first lifetime evaluation method for the pellicle film, and the first lifetime evaluation method for the pellicle film are the same as in the first embodiment.

[0238] In the fifth modified example, the structure of the pellicle film, the thickness of the pellicle film, and the CNTs are the same as in the first embodiment. In the fifth modification, the pellicle film may comprise other layers, similar to the first embodiment.

[0239] (6.2) Pellicle The pellicle according to the fifth modified example comprises a pellicle membrane according to the fifth modified example and a pellicle frame. The pellicle membrane is supported by the pellicle frame. The pellicle according to the fifth modified example comprises a pellicle film according to the fifth modified example, and therefore produces the same effect as the pellicle film according to the fifth modified example. In the fifth modification, the pellicle may further comprise an adhesive layer. The pellicle frame and adhesive layer are the same as in the first embodiment.

[0240] (6.3) Exposure master plate The exposure master according to the fifth modification comprises a photomask and a pellicle according to the fifth modification. The photomask is a master having a circuit pattern. The pellicle is attached to the surface on which the circuit pattern is formed on the photomask. The exposure master according to the fifth modified example is equipped with a pellicle according to the fifth modified example, and therefore produces the same effect as the pellicle according to the fifth modified example. The mounting method and the photomask, etc., are the same as in the first embodiment.

[0241] (6.4) Exposure apparatus The exposure apparatus according to the fifth modification comprises an EUV light source, an exposure master according to the fifth modification, and an optical system. The EUV light source emits EUV light as exposure light. The optical system guides the exposure light emitted from the EUV light source to the exposure master. The exposure master is positioned so that the exposure light emitted from the EUV light source passes through the pellicle film and irradiates the photomask. Therefore, the exposure apparatus according to the fifth modified example achieves the same effect as the exposure master according to the fifth modified example. Furthermore, because the exposure apparatus according to the fifth modified example has the above configuration, it can form finely detailed patterns (for example, with a line width of 32 nm or less), and can also perform pattern exposure with reduced resolution defects due to foreign matter. A known EUV light source can be used. A known optical system can be used.

[0242] (6.5) Method for manufacturing pellicle film The method for manufacturing a pellicle film according to the fifth modified example is a method for manufacturing a pellicle film according to the fifth modified example, and includes a coating step. In the coating step, a dispersion liquid containing a plurality of CNTs synthesized by direct injection pyrolysis synthesis is applied to a substrate. The method for manufacturing a pellicle film according to the fifth modified example has the above configuration, and therefore yields a pellicle film in which the average ratio of the gap area is 30% or less. In the fifth modified example, the method for manufacturing the pellicle film preferably includes a preparation step, a dispersion preparation step, a washing step, and a separation step, in addition to the coating step. The coating step, preparation step, dispersion preparation step, washing step, and separation step are the same as in the first embodiment.

[0243] In the fifth modified example, the method for manufacturing the pellicle film preferably further includes a cleaning step of alkaline cleaning the coated film obtained in the coating step. This results in a pellicle film from which the dispersant contained in the coated film has been removed.

[0244] (7) Sixth variation (Defect (G / D) distribution) (7.1) Pellicle membrane The pellicle film according to the sixth modified example contains a plurality of carbon nanotubes (CNTs) forming a bundle, and it is preferable that the ratio (G / D) is 0.8 or higher. If the ratio (G / D) is within the above range, the etching reaction of CNTs will not proceed easily when CNTs react with hydrogen plasma and CNTs are etched.

[0245] The pellicle according to the sixth modified example is the same as the pellicle according to the first embodiment, except that it does not need to have a ratio (G / D) of 0.8 or more, and the average value of the linearity parameter represented by formula (1) above is 0.10 or less. The description of the sixth modified example of this disclosure can be made by reference to the description of the first embodiment of this disclosure.

[0246] The ratio (G / D), the preferred range of the ratio (G / D), and the method for measuring the ratio (G / D) are the same as in the first embodiment.

[0247] In the sixth modified example, it is preferable that the average value of the linearity parameter expressed by the above formula (1) for multiple CNTs is 0.10 or less. If the average value of the linearity parameters of multiple CNTs is 0.10 or less, the film will be less prone to thinning even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment. The linearity parameter, the preferred range of the mean value of the linearity parameter, and the method for measuring the linearity parameter are the same as in the first embodiment.

[0248] In the sixth modified example, the multiple CNTs form multiple bundles, and the average value of the packing density parameters of the multiple bundles, as expressed by formula (2) above, may be 0.20 or less. In the sixth modified example, since the pellicle film has the above-described structure, it is less prone to film reduction even when exposed to hydrogen plasma. This is presumed to be due to the same reasons as in the first embodiment. The packing density parameters, the preferred range of the average value of the packing density parameters, and the method for measuring the packing density parameters are the same as in the first embodiment.

[0249] In the sixth modified example, it is preferable that the average value of the packing density parameters of the multiple bundles is 0.15 or less. If the average value of the packing density parameters of multiple bundles is 0.15 or less, the loss of the pellicle film can be further suppressed even when exposed to hydrogen plasma.

[0250] In the sixth modified example, the pellicle film preferably contains a plurality of carbon nanotubes forming a bundle, and the second diffraction peak ratio is 1.3 or higher. If the second diffraction peak ratio is within the above range, the diffusion of hydrogen radicals into the single bundle is further suppressed. As a result, the pellicle film exhibits higher lifetime characteristics and is less prone to film degradation even when exposed to hydrogen plasma. The second diffraction peak ratio, the preferred range of the second diffraction peak ratio, and the method for measuring the second diffraction peak are the same as in the first embodiment.

[0251] In the sixth modified example, the pellicle film contains multiple carbon nanotubes forming a bundle, and the smoothness evaluation value is 0.070 (nm). 2 It is preferable that it is less than or equal to / nm. If the smoothness evaluation value is within the range described above, the loss of the pellicle film can be suppressed even when the pellicle film is exposed to hydrogen plasma. The smoothness evaluation value, the preferred range of the smoothness evaluation value, and the method for measuring the smoothness evaluation value are the same as in the first embodiment.

[0252] The first diffraction peak ratio, the average value of the gap area ratio, the first lifetime evaluation method for the pellicle film, and the first lifetime evaluation method for the pellicle film are the same as in the first embodiment.

[0253] In the sixth modified example, the structure of the pellicle film, the thickness of the pellicle film, and the CNTs are the same as in the first embodiment. In the sixth modification, the pellicle film may comprise other layers, similar to the first embodiment.

[0254] (7.2) Pellicle The pellicle according to the sixth modified example comprises a pellicle membrane according to the sixth modified example and a pellicle frame. The pellicle membrane is supported by the pellicle frame. The pellicle according to the sixth modified example comprises a pellicle film according to the sixth modified example, and therefore produces the same effect as the pellicle film according to the sixth modified example. In the sixth modification, the pellicle may further comprise an adhesive layer. The pellicle frame and adhesive layer are the same as in the first embodiment.

[0255] (7.3) Exposure master The exposure master according to the sixth modified example comprises a photomask and a pellicle according to the sixth modified example. The photomask is a master image having a circuit pattern. The pellicle is attached to the surface on which the circuit pattern is formed on the photomask. The exposure master according to the sixth modified example is equipped with a pellicle according to the sixth modified example, and therefore produces the same effect as the pellicle according to the sixth modified example. The mounting method and the photomask, etc., are the same as in the first embodiment.

[0256] (7.4) Exposure apparatus The exposure apparatus according to the sixth modification comprises an EUV light source, an exposure master according to the sixth modification, and an optical system. The EUV light source emits EUV light as exposure light. The optical system guides the exposure light emitted from the EUV light source to the exposure master. The exposure master is positioned so that the exposure light emitted from the EUV light source passes through the pellicle film and irradiates the photomask. Therefore, the exposure apparatus according to the sixth modified example achieves the same effect as the exposure master plate according to the sixth modified example. Furthermore, because the exposure apparatus according to the sixth modified example has the above configuration, it can form finely detailed patterns (for example, with a line width of 32 nm or less), and can also perform pattern exposure with reduced resolution defects due to foreign matter. A known EUV light source can be used. A known optical system can be used.

[0257] (7.5) Method for manufacturing pellicle film The method for manufacturing a pellicle film according to the sixth modified example is a method for manufacturing a pellicle film according to the sixth modified example, and includes a coating step. In the coating step, a dispersion liquid containing a plurality of CNTs synthesized by direct injection pyrolysis synthesis is applied to a substrate. The method for manufacturing a pellicle film according to the sixth modified example has the above configuration, and therefore yields a pellicle film with a ratio (G / D) of 0.8 or higher. In the sixth modified example, the method for manufacturing the pellicle film preferably includes a preparation step, a dispersion preparation step, a washing step, and a separation step, in addition to the coating step. The coating step, preparation step, dispersion preparation step, washing step, and separation step are the same as in the first embodiment.

[0258] In the sixth modified example, the method for manufacturing the pellicle film preferably further includes a cleaning step of alkaline cleaning the coated film obtained in the coating step. This results in a pellicle film from which the dispersant contained in the coated film has been removed.

[0259] Embodiments of the present disclosure have been described above with reference to the drawings. However, the present disclosure is not limited to the embodiments described above, and can be implemented in various forms without departing from its essence. The drawings schematically show each component for ease of understanding, and the thickness, length, number, etc. of each component shown may differ from the actual dimensions due to the convenience of drawing creation. The materials, shapes, dimensions, etc. of each component shown in the above embodiments are examples and are not particularly limiting, and various modifications are possible without substantially departing from the effects of the present disclosure. [Examples]

[0260] The present disclosure will be described in more detail below with reference to examples, but the invention of this disclosure is not limited to these examples. In this embodiment, the film thickness of the exposure region and the film thickness of the peripheral region were determined by the method described above.

[0261] (Example 1) [Preparation process] As multiple CNTs, several single-walled carbon nanotubes synthesized by the eDIPS method (manufactured by Meijo Nanocarbon Co., Ltd., product name: "EC1.5-P", tube diameter: 1 nm to 3 nm, tube length: 100 nm or more) were prepared.

[0262] [Dispersion liquid preparation process] To 30 mg of multiple carbon nanotubes (CNTs), 70 mL of isopropyl alcohol and 30 mL of ethanol were added, and then 30 mg of polyacrylic acid was added as an additive. The mixture was stirred using a magnetic stirrer at 1000 rpm (revolutions per minute) at 40°C for 18 hours. The resulting suspension was then ultrasonically dispersed using a probe-type homogenizer at 40% output for a total of 30 minutes to obtain a CNT dispersion.

[0263] [Coating process] An 8-inch silicon wafer (hereinafter referred to as "silicon substrate") was prepared. A CNT dispersion was spin-coated onto the silicon substrate at a rotational speed of 1500 rpm. This resulted in a coated film being formed on the silicon substrate.

[0264] [Washing process] The coated film was alkaline-washed with tetramethylammonium hydroxide (hereinafter referred to as "TMAH") to remove polyacrylic acid from the unwashed CNT film and then dried. This yielded a CNT film.

[0265] Hereinafter, the silicon substrate and the CNT film formed on the silicon substrate will be collectively referred to as the "film-coated silicon substrate."

[0266] [Separation process] A silicon substrate with a film attached was immersed in a water bath. In the water, the CNT film was peeled off from the silicon substrate. The CNT film that was peeled off from the silicon substrate was left in the water, and the silicon substrate was removed from the water. At this time, the CNT film was floating on the water surface. This yielded a pellicle film consisting of a CNT film with a mesh structure.

[0267] [Pellicle manufacturing process] A silicone frame (hereinafter also referred to as the "pellicle frame") was prepared as the pellicle frame. The pellicle frame was cylindrical. The pellicle frame had through holes. The through holes were formed along the thickness direction of the pellicle frame. The outline of the through hole, viewed from one side in the thickness direction of the pellicle frame, was a square with sides of 10 mm.

[0268] The CNT film floating on the water surface was scooped up with a pellicle frame. This resulted in a pellicle with the CNT film positioned on the pellicle frame. The CNT film on the obtained pellicle was in contact with the pellicle frame and covered the entire area of ​​the through-holes in the pellicle frame.

[0269] (Example 2) In the cleaning process, the pellicle was obtained in the same manner as in Example 1, except that the CNT film was washed with water instead of the coated film being washed with TMAH.

[0270] (Comparative Example 1) [Preparation process] As CNTs, single-walled carbon nanotubes (WYNTs) were synthesized using the method described in Patent Document 2 (SG method).

[0271] [Coating process] 300 mg of CNTs synthesized by the SG method and 1 g of organic side-chain flavin as a dispersant were added to 100 mL of toluene. After stirring with a magnetic stirrer at approximately 480 rpm for 2 hours, the suspension was ultrasonically dispersed using a probe-type homogenizer at 40% power for a total of 2 hours. During this time, it was cooled with ice for 5 minutes every 20 minutes. The resulting CNT dispersion was degassed. A silicon substrate was prepared. A CNT dispersion was blade-coated onto the silicon substrate and dried. The gap between the blade and the silicon substrate was 25 μm. This yielded a CNT film with a network structure. The thickness of the unwashed CNT film was 20 nm.

[0272] [Washing process] The unwashed CNT film was washed with chloroform to remove the organic side-chain flavins, and then dried. This yielded a CNT film with a network structure.

[0273] [Separation process and pellicle manufacturing process] A pellicle was obtained by performing the separation step and the pellicle manufacturing step in the same manner as in Example 1.

[0274] (Measurement of linear parameters and packing density parameters) The linearity parameter and packing density parameter of the pellicles obtained in Example 1, Example 2, and Comparative Example 1 were measured using the method described above. Transmission electron microscope images and limited-field electron diffraction images were obtained using a field emission transmission electron microscope (JEOL Ltd., Model: ARM200F). Thin sections for cross-sectional observation were prepared using a FIB processing apparatus (FI Japan Co., Ltd., Model: HeliosG4UX). The measurement results are shown in Table 2. The pellicles obtained in Example 1, Example 2, and Comparative Example 1 contained multiple CNTs. The majority of the multiple CNTs in Example 1, Example 2, and Comparative Example 1 were single-layer or two-layer, with a small number consisting of three- to four-layer CNTs, forming bundles.

[0275] (Measurement of the first diffraction peak ratio) The first diffraction peak ratio of the pellicle obtained in Example 1 was measured using the method described above. Specifically, in the pellicle obtained in Example 1, the center was q = 2.0 nm. -1 ~3.0nm -1 For the diffraction peak located at [location], the first diffraction peak ratio, calculated by combining the integrated value of the peak in the film thickness direction (area value in the Gaussian function) and the integrated value of the peak in the film plane direction (area value in the Gaussian function), was 35.

[0276] (Measurement of the second diffraction peak ratio) The second diffraction peak ratio was measured for the pellicle obtained in Example 1 and the pellicle obtained in Comparative Example 1 using the method described above. The second diffraction peak ratio for Example 1 was 4.0. The second diffraction peak ratio for Comparative Example 1 was 1.0.

[0277] (Measurement of smoothness evaluation value) For the pellicle obtained in Example 1, the smoothness evaluation value [nm] 2 The smoothness evaluation value [nm] of Example 1 was measured by the method described above. 2 The value of [ / nm] was 0.031 nm. The scale of the TEM image used in Example 1 was 0.02 nm per pixel.

[0278] (Measurement of the average percentage of gap area) The average percentage of the gap area was measured for the pellicle obtained in Example 1 and the pellicle obtained in Comparative Example 1 using the method described above. The average percentage of the gap area for Example 1 was 24%. The average percentage of the gap area for Comparative Example 1 was 36%.

[0279] (Measurement of the ratio (G / D)) The ratio (G / D) of the pellicle obtained in Example 1 and the pellicle obtained in Comparative Example 1 was measured using the method described above. The minimum value of the ratio (G / D) for Example 1 was 1.10. The maximum value of the ratio (G / D) for Comparative Example 1 was 0.77.

[0280] (Measurement of film loss rate) The film loss rate for the pellicles obtained in Example 1, Example 2, and Comparative Example 1 was measured as follows.

[0281] A silicon substrate was prepared. Ethanol was dropped onto the silicon substrate, and the pellicle film of the pellicle was placed facing the silicon substrate, thus placing the pellicle on the silicon substrate. The ethanol was dried, and the pellicle film was tightly adhered to the silicon substrate without any gaps. The silicon substrate was fixed in place, and the pellicle frame of the pellicle was lifted, transferring the self-supporting film portion to the silicon substrate. A test piece was obtained as a result. The film thickness of the self-supporting portion of the test piece was measured using the method described above. The thickness of the self-supporting portion of Example 1 was 24 nm. The thickness of the self-supporting portion of Example 2 was 23 nm. The thickness of the self-supporting portion of Comparative Example 1 was 23 nm.

[0282] The test piece was subjected to hydrogen plasma irradiation. In hydrogen plasma irradiation, the self-supporting film is exposed to hydrogen plasma. This exposes the self-supporting film to a hydrogen plasma environment similar to that of EUV lithography, causing etching and chemical changes in the self-supporting film. Etching of the self-supporting film due to exposure to hydrogen plasma results in a reduction in film thickness.

[0283] For details, a parallel-plate type plasma CVD apparatus (manufactured by Japan Create Co., Ltd., cathode electrode size Φ100mm) was used to irradiate a test piece with hydrogen plasma under the following processing conditions. The test piece was placed on the anode electrode (ground), and after vacuuming for 30 minutes, hydrogen gas was flowed at 20 Pa for 5 minutes before plasma irradiation was performed.

[0284] <Hydrogen plasma treatment conditions> Chamber vacuum level: Pressure < 1e -3 Pa Material gas: H2 (G1 grade) Gas flow rate: 50 sccm Processing pressure: 20 Pa (0.15 Torr) RF power: 100W Self-bias voltage: -490V Processing time: 120 seconds

[0285] The thickness of the self-supporting film portion of the test piece subjected to hydrogen plasma irradiation was measured using the method described above.

[0286] The film thickness of the self-supporting film before hydrogen plasma irradiation (hereinafter referred to as "pre-irradiation measurement") and the film thickness of the self-supporting film after hydrogen plasma irradiation (hereinafter referred to as "post-irradiation measurement") were used to calculate the film thickness reduction rate using the following formula (3). The calculation results are shown in Table 2. A low film thinning rate indicates that the etching rate of the self-supporting film portion by hydrogen plasma is slow, meaning it is less susceptible to etching by hydrogen plasma irradiation. A low film thinning rate also indicates that the pellicle film has high EUV irradiation resistance in an EUV exposure environment. Equation (3): Film loss rate = ((Measurement value before irradiation - Measurement value after irradiation) / Measurement value before irradiation) × 100

[0287] [Table 2]

[0288] The pellicle film of Comparative Example 1 contained multiple CNTs, but the average value of the linearity parameters of the multiple CNTs was greater than 0.10. Therefore, the film loss rate of Comparative Example 1 was 33%.

[0289] Each pellicle film in Example 1 and Example 2 contained multiple carbon nanotubes (CNTs), and the average value of the linearity parameters of the multiple CNTs was 0.10 or less. Therefore, the film loss rate for each of Example 1 and Example 2 was 30% or less, which was lower than the film loss rate of Comparative Example 1. As a result, it was found that each of the pellicle films in Example 1 and Example 2 was less susceptible to film loss when exposed to hydrogen plasma than conventional films.

[0290] A comparison of Example 1 and Example 2 revealed that when the average value of the packing density parameters of multiple bundles is 0.15 or less, the film is less prone to thinning even when exposed to hydrogen plasma.

[0291] For pellicle films with a thickness of 20 nm or less, to precisely measure film loss, it is possible to measure the thickness while the pellicle film is laminated on a silicon substrate with high reflectivity in the wavelength range of 220 nm to 300 nm. This allows for the detection of slight changes in reflectivity due to changes in film thickness, and as a result, the thickness can be evaluated with a measurement accuracy of approximately 0.1 nm.

[0292] The disclosure of Japanese Patent Application No. 2021-138015, filed on 26 August 2021, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. Contains multiple carbon nanotubes, Some of the aforementioned multiple carbon nanotubes form multiple bundles, The diffraction peak ratio is between 4.0 and 100. The diffraction peak ratio represents the ratio of the height of the second Gaussian function, which is a component of the second fitting function obtained by fitting the second plot curve, to the height of the first Gaussian function, which is a component of the first fitting function obtained by fitting the first plot curve, in a limited-field diffraction image obtained by observing the surface of the pellicle film with a transmission electron microscope. The first plotted curve is a profile of the diffraction intensity in the direction in which the diffraction intensity originating from the bundle lattice of the bundle is weak, with respect to the scattering vector q. The second plotted curve is a profile of the diffraction intensity in the direction in which the diffraction intensity is strong relative to the scattering vector q. The first fitting function is defined as the scattering vector q = 1.5 nm －１ ~4.0 nm －１ Within this range, the baseline function common to the first plotted curve and the second plotted curve, and the peak center position of the first plotted curve are q = 2.0 nm －１ ~3.0 nm －１ A function that can be expressed as the sum of the aforementioned first Gaussian function in the range, The second fitting function is the baseline function and the peak center position of the second plot curve is g = 2.0 nm. －１ ~3.0 nm －１ This is a function that can be expressed as the sum of the aforementioned second Gaussian function in the range, The height of the first Gaussian function is when the scattering vector q is q = 2.0 nm. －１ ~3.0 nm －１ The local maximum value of the first Gaussian function in the range is shown, The height of the second Gaussian function indicates the maximum value of the second Gaussian function in the range where the scattering vector q is q = 2.0 nm －１ to 3.0 nm －１ and The baseline function is y = αq - β (where y represents the diffraction intensity, q represents the scattering vector, and α and β each represent positive values), The ratio of the intensity of the G band to the intensity of the D band (G / D) at seven locations within a predetermined bundle region in a cross-section of the pellicle film cut along the axial direction of the bundle is 0.80 or higher. The intensity of the D band and the intensity of the G band are measured by Raman imaging. The predetermined bundle region refers to a region within a bundle with a thickness of 10 nm or more and a spatial resolution of 20 nm or less in the 500 nm × 500 nm measurement area of ​​the cross-section. The intensity of the D band is the maximum value of the Raman scattering intensity within the range of a Raman shift from 1300 cm⁻¹ to 1400 cm⁻¹. The intensity of the G-band is the maximum value of the Raman scattering intensity within the range of a Raman shift from 1550 cm⁻¹ to 1610 cm⁻¹ in the pellicle film.

2. The pellicle film according to claim 1, wherein the average value of the linearity parameter of the plurality of carbon nanotubes, represented by the following formula (1), is 0.10 or less. Equation (1): Linearity parameter = Standard deviation Sa of the width of a single carbon nanotube / Average value Aa of the width (In formula (1) above, The standard deviation Sa and the average value Aa are each calculated based on 11 measurement points obtained by measuring the width of one carbon nanotube at 2 nm intervals along the longitudinal direction of one carbon nanotube.

3. The pellicle film according to claim 1, wherein the average value of the packing density parameters of the plurality of bundles, represented by the following formula (2), is 0.20 or less. Equation (2): Packing density parameter = Standard deviation Sb of the distance between the centers of multiple carbon nanotubes constituting one bundle / Average value Ab of the distance between the centers (In the above formula (2), The distance between the center points is the length of the straight line connecting the center points in a 20 nm × 20 nm range transmission electron microscope image containing one bundle of the pellicle film obtained by cutting the pellicle film along the thickness direction of the pellicle film, after identifying the center point of each annular contour line of multiple carbon nanotubes in the transmission electron microscope image, such that multiple triangles satisfying predetermined conditions are formed. The aforementioned predetermined conditions include that the sides of the plurality of triangles do not intersect, that three center points are selected such that the sum of the lengths of the three sides of the triangles is minimized, and that the interior angle of the outermost triangle among the plurality of triangles is less than 120°. The standard deviation Sb and the mean Ab are each calculated based on a plurality of distances between center points that are less than or equal to a predetermined value. The predetermined value is obtained by multiplying the average value of the distances between the center points, from the shortest distance (1st) to the predetermined rank, by 1.

6. The predetermined rank is indicated by the integer obtained by rounding the first decimal place of the number obtained by multiplying the total distance between the multiple center points by 0.

8.

4. The pellicle film according to claim 3, wherein the average value of the packing density parameter is 0.15 or less.

5. The smoothness evaluation value is 0.070 (nm). ２ It is less than or equal to / nm, The aforementioned smoothness evaluation value represents the value obtained by dividing the area between the contour line of the carbon nanotube and the approximation curve of the contour line by the length of the approximation curve. The aforementioned contour line is obtained by tracing the CNT wall portion that appears as a dark line in a transmission electron microscope image of the surface of the pellicle film at a resolution of 100 pixels or more with a length of 5 nm. The aforementioned approximation curve is a curve drawn by quadratic spline interpolation of the coordinates of the contour line of the CNT, The outline and approximate curve of the carbon nanotube were extracted from 20 carbon nanotubes. The length of the outline is 20 nm for each carbon nanotube. The pellicle film according to claim 1.

6. Pellicle frame and A pellicle film according to any one of claims 1 to 5, supported on the pellicle frame, A pellicle equipped with this feature.

7. Photomask and The pellicle according to claim 6 attached to the photomask and An exposure master plate equipped with the following features.

8. An EUV light source that emits EUV light as exposure light, The exposure plate according to claim 7, An optical system that guides the exposure light emitted from the EUV light source to the exposure plate, Equipped with, The exposure master plate is arranged such that the exposure light emitted from the EUV light source passes through the pellicle film and irradiates the photomask.

9. A method for producing a pellicle film according to any one of claims 1 to 5, A method for producing a pellicle film, comprising a coating step of applying a dispersion liquid containing multiple carbon nanotubes synthesized by direct injection pyrolysis synthesis to a substrate.

10. A method for manufacturing a pellicle film, A coating step involves applying a dispersion liquid containing multiple carbon nanotubes synthesized by direct injection pyrolysis synthesis to a substrate, A cleaning step in which the coated film obtained in the above coating step is to perform alkaline cleaning. Includes, The pellicle film contains a plurality of carbon nanotubes, Some of the aforementioned multiple carbon nanotubes form multiple bundles, The diffraction peak ratio is 1.3 or higher. The diffraction peak ratio represents the ratio of the height of the second Gaussian function, which is a component of the second fitting function obtained by fitting the second plot curve, to the height of the first Gaussian function, which is a component of the first fitting function obtained by fitting the first plot curve, in a limited-field diffraction image obtained by observing the surface of the pellicle film with a transmission electron microscope. The first plotted curve is a profile of the diffraction intensity in the direction in which the diffraction intensity originating from the bundle lattice of the bundle is weak, with respect to the scattering vector q. The second plotted curve is a profile of the diffraction intensity in the direction in which the diffraction intensity is strong relative to the scattering vector q. The first fitting function is a function expressed as the sum of a baseline function common to the first plot curve and the second plot curve in the range of q = 1.5 nm - 1 to 4.0 nm - 1, and a first Gaussian function in which the peak center position of the first plot curve is in the range of q = 2.0 nm - 1 to 3.0 nm - 1. The second fitting function is a function expressed as the sum of the baseline function and the second Gaussian function in which the peak center position of the second plot curve is in the range of g = 2.0 nm - 1 to 3.0 nm - 1. The height of the first Gaussian function indicates the maximum value of the first Gaussian function in the range of q = 2.0 nm - 1 to 3.0 nm - 1, where the scattering vector q is in the range of q = 2.0 nm - 1 to 3.0 nm - 1. A method for manufacturing a pellicle film, wherein the height of the second Gaussian function is the maximum value of the second Gaussian function in the range of q = 2.0 nm - 1 to 3.0 nm - 1 when the scattering vector q is in that range.

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