Pellicle film and pellicle, as well as, visible light transmittance of pellicle film, standard deviation of visible light transmittance, and method for measuring variation coefficient of visible light transmittance

Abstract

To provide a pellicle film that, while securing high transmittance of EUV and suppressing variation of EUV transmittance, has small deformation amount, while securing high transmittance of EUV.SOLUTION: A pellicle film 10 having a porous structure. The pellicle film 10 contains carbon nanotubes. The pellicle film 10 includes a first pellicle film surface 11 and a second pellicle film surface 12 on the opposite side of the first pellicle film surface 11, and a visible light transmittance calculated by the following equation (Equation 1) is 60% or more and 85% or less, and the standard deviation of the visible light transmittance is 0.56% or less. T={(Tp-Td) / (Tb-Td)}×100 (Equation 1)(In Equation 1, T represents the visible light transmittance of the pellicle film 10; Tp represents the pixel value in the image of the pellicle film 10 in the light-transmitting state; Tb represents the pixel value in the image at the imaging position in the bright state; Td represents the pixel value in the image at the imaging position in the dark state.)SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pellicle film, a pellicle, and a measurement method for measuring the visible light transmittance and standard deviation of the visible light transmittance of a pellicle film. [Background technology]

[0002] In a manufacturing process of a semiconductor device or the like, for example, a photoresist is applied to a substrate such as a semiconductor wafer, and the substrate with the photoresist applied is irradiated with light using a photomask, and the photoresist is removed, thereby forming a desired circuit pattern on the substrate.

[0003] When a photomask is irradiated with light while foreign matter is attached to it, the attached foreign matter may interfere with the circuit pattern formed on the substrate. For this reason, a pellicle equipped with a pellicle film for capturing foreign matter may be used to prevent foreign matter from adhering to the photomask. The pellicle is placed above the photomask at a distance such that the pellicle film does not come into contact with the photomask.

[0004] In recent years, the use of extreme ultraviolet (EUV) has been considered to form finer circuit patterns. EUV refers to light with a wavelength of 1 nm or more and 100 nm or less. Specifically, light rays of approximately 13.5 nm ± 0.3 nm are beginning to be used as EUV. When EUV is irradiated onto a pellicle film, the EUV passes through the film, but some of the irradiated EUV is absorbed by the film. The absorbed EUV light energy is converted into thermal energy, causing the temperature of the pellicle film to rise. For this reason, pellicle films are required to have EUV transmittance, heat resistance, durability, etc.

[0005] Carbon nanotubes are being considered as one of the materials to be used for the pellicle membrane of pellicles used in the process of forming circuit patterns using EUV.

[0006] For example, Patent Document 1 discloses a pellicle film for exposure that includes a carbon nanotube film containing carbon nanotubes. The carbon nanotube film disclosed in Patent Document 1 has a transmittance of 80% or more for EUV light at a wavelength of 13.5 nm, a thickness of 1 nm or more and 50 nm or less, and a reflectance 3σ of 15% or less. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2023-106455 Summary of the Invention [Problem to be solved by the invention]

[0008] In the pellicle film containing carbon nanotubes disclosed in Patent Document 1, the reflectance measured using a spectroscopic film thickness meter is used as a method for evaluating the uniformity of EUV transmittance. The pellicle film disclosed in Patent Document 1 achieves improved uniformity of EUV transmittance by increasing the uniformity of the pellicle film thickness. However, the values ​​measured using the spectroscopic film thickness meter only indirectly evaluate the uniformity of EUV transmittance and do not directly evaluate the variation in the transmittance of light passing through the pellicle film. For this reason, there are concerns that the pellicle film disclosed in Patent Document 1 does not actually have sufficiently high uniformity of EUV transmittance. Furthermore, if the uniformity of the EUV transmittance of the pellicle film is not sufficiently high, the pellicle film is prone to deformation, which in turn reduces its mechanical strength. Thus, further improvements in pellicle films are needed.

[0009] The present invention aims to provide a pellicle film containing carbon nanotubes that ensures high EUV transmittance while suppressing variations in EUV transmittance and exhibiting small deformation, and a pellicle using the pellicle film. Another object of the present invention is to provide a measurement method for measuring the visible light transmittance and standard deviation of the visible light transmittance of a pellicle film, which can be used as an index of the essential variations in EUV transmittance of the pellicle film. [Means for solving the problem]

[0010] [1] A pellicle membrane having a porous structure, the pellicle membrane comprises carbon nanotubes; The pellicle membrane has a first pellicle membrane surface and a second pellicle membrane surface opposite to the first pellicle membrane surface, (1) The second pellicle film surface side was placed at an imaging position, and white light with a wavelength of 400 nm or more and 750 nm or less was irradiated from the second pellicle film surface side. The image was taken from the first pellicle film surface side. The area was 14,300 mm 2 An image of a pellicle membrane in a light-transmitting state at 700,000 pixels or more; (2) An image of the imaging position in a bright state at or above the pixel of the area, obtained by imaging the imaging position that does not include the pellicle film under irradiation with the white light; (3) An image of the imaging position in a dark state at or above the pixel of the area, obtained by imaging the imaging position not including the pellicle film in a light-shielded state, is based on The visible light transmittance calculated by the following formula (Mathematical Formula 1) is 60% or more and 85% or less, and the standard deviation of the visible light transmittance is 0.56% or less. Pellicle membrane. T={(Tp-Td) / (Tb-Td)}×100…(Math 1) (In the above formula (Equation 1), T represents the visible light transmittance of the pellicle film, Tp represents a pixel value representing the transmission of the white light in the image of the pellicle film in the light-transmitting state, Tb represents a pixel value representing the transmission of the white light in the image of the bright state imaging position, and Td represents a pixel value when the white light is not irradiated in the image of the dark state imaging position.)

[0011] [2] [1] The pellicle membrane according to The coefficient of variation of the visible light transmittance is 0.68 or less. Pellicle membrane.

[0012] [3] In the pellicle membrane according to [1] or [2], The length of the carbon nanotubes is 0.1 μm or more and 1000 μm or less. Pellicle membrane.

[0013] [4] [1] The pellicle membrane according to any one of [3] to [4], The cross-sectional diameter of the carbon nanotube is 0.2 nm or more and 50 nm or less. Pellicle membrane.

[0014] [5] [1] to [4], wherein the pellicle membrane is have independence, Pellicle membrane.

[0015] [6] [1] to [5], and a pellicle membrane according to any one of [1] to [5]. A support having a frame and an opening surrounded by the frame, and supporting the pellicle membrane; Equipped with Pellicle.

[0016] [7] A method for measuring the visible light transmittance and standard deviation of the visible light transmittance of a pellicle film having a porous structure, comprising: providing a pellicle membrane including carbon nanotubes and having a first pellicle membrane surface and a second pellicle membrane surface opposite the first pellicle membrane surface; placing the prepared pellicle membrane at the imaging position with the second pellicle membrane surface facing the imaging position; a step of irradiating the placed pellicle film with white light having a wavelength of 400 nm or more and 750 nm or less from the second pellicle film surface side to transmit the white light through the pellicle film; In a state where the white light is irradiated, an image is taken by an imaging means from the side of the first pellicle film that is not irradiated with the white light, and an area of ​​14,300 mm 2 Acquiring an image of the pellicle membrane in a light-transmitting state at 700,000 pixels or more; With the white light irradiated, the imaging position not including the pellicle film was imaged, and an area of ​​14,300 mm 2 acquiring an image of a bright state at an imaging position of 700,000 pixels or more; The white light was not irradiated and the imaging position not including the pellicle film was imaged in a light-shielded state, and an area of ​​14,300 mm 2 acquiring an image of an imaging position in a dark state at 700,000 pixels or more; Calculating the visible light transmittance and the standard deviation of the visible light transmittance of the pellicle film based on the image of the pellicle film in the light-transmitting state, the image of the image capturing position in the bright state, and the image of the image capturing position in the dark state; Equipped with The visible light transmittance of the pellicle film is calculated by the following formula (Formula 1): Measurement method. T={(Tp-Td) / (Tb-Td)}×100…(Math 1) (In the above formula (Equation 1), T represents the visible light transmittance of the pellicle film, Tp represents a pixel value representing the transmission of the white light in the image of the pellicle film in the light-transmitting state, Tb represents a pixel value representing the transmission of the white light in the image of the bright state imaging position, and Td represents a pixel value when the white light is not irradiated in the image of the dark state imaging position.) [Effects of the Invention]

[0017] According to one aspect of the present invention, a pellicle film containing carbon nanotubes can be provided, which ensures high EUV transmittance while suppressing variation in EUV transmittance and exhibiting small deformation, and a pellicle using the pellicle film can be provided. Also, according to another aspect of the present invention, a measurement method can be provided for measuring the visible light transmittance and standard deviation of the visible light transmittance of a pellicle film, which can be used as an index of the essential variation in EUV transmittance of the pellicle film. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating an example of a pellicle membrane according to the present embodiment. [Figure 2A] FIG. 1 is an explanatory diagram schematically illustrating an example of a measurement method for measuring the visible light transmittance and standard deviation of the visible light transmittance of a pellicle film according to this embodiment. [Figure 2B] FIG. 1 is an explanatory diagram schematically illustrating an example of a measurement method for measuring the visible light transmittance and standard deviation of the visible light transmittance of a pellicle film according to this embodiment. [Figure 2C] FIG. 1 is an explanatory diagram schematically illustrating an example of a measurement method for measuring the visible light transmittance and standard deviation of the visible light transmittance of a pellicle film according to this embodiment. [Figure 3] FIG. 1 is a plan view schematically illustrating an example of a pellicle according to an embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view showing the IV-IV cross section of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, a description will be given of a pellicle membrane, a pellicle, and a method for measuring the visible light transmittance and standard deviation of the visible light transmittance of a pellicle membrane according to a preferred embodiment of the present invention.

[0020] [Pellicle membrane] The pellicle membrane according to this embodiment has a porous structure. The pellicle membrane contains carbon nanotubes. The pellicle membrane has a first pellicle membrane surface and a second pellicle membrane surface opposite to the first pellicle membrane surface. The pellicle membrane is then (1) placed with the second pellicle membrane surface side at an imaging position, and imaged from the first pellicle membrane surface side while irradiating the second pellicle membrane surface side with white light having a wavelength of 400 nm or more and 750 nm or less, with an area of ​​14,300 mm. 2 (1) an image of a pellicle membrane in a light-transmitted state at 700,000 pixels or more of the area, (2) an image of a bright state at an imaging position at least at the pixels of the area where the imaging position does not contain the pellicle membrane, taken under the condition that the white light is irradiated, and (3) an image of a dark state at an imaging position at least at the pixels of the area where the imaging position does not contain the pellicle membrane, taken under the condition that the light is blocked, the visible light transmittance calculated by the following formula (Equation 1) is 60% or more and 85% or less, and the standard deviation of the visible light transmittance is 0.56% or less. Note that the images related to (2) and (3) above are images with the same area and the same number of pixels as the image (1) above. T={(Tp-Td) / (Tb-Td)}×100…(Math 1) (In the above formula (Equation 1), T represents the visible light transmittance of the pellicle film, Tp represents a pixel value representing the transmission of the white light in the image of the pellicle film in the light-transmitting state, Tb represents a pixel value representing the transmission of the white light in the image of the bright state imaging position, and Td represents a pixel value when the white light is not irradiated in the image of the dark state imaging position.)

[0021] The pellicle membrane according to the present embodiment has the above-described configuration, which ensures high EUV transmittance while suppressing variations in EUV transmittance and minimizing deformation. Specifically, in the pellicle membrane according to the present embodiment, the visible light transmittance calculated by the above formula (Mathematical Formula 1) is 60% or more, so that the EUV transmittance can be adjusted to 93% or more.

[0022] It is known that pellicle films containing CNTs have a correlation between their light transmittance at wavelengths of 13.5 nm and 550 nm (see, for example, Figure 4(a) in Marina, Y, et al. “CNT EUV pellicle tunability and performance in a scanner-like environment,” Proc. SPIE 11609, Extreme Ultraviolet (EUV) Lithography XII, 116090Y, (23 March 2021). Figure 4(a). ; doi: 10.1117 / 12.2584519). The inventors then discovered that if the visible light transmittance of the pellicle film is 60% or more, the EUV transmittance can be adjusted to 93% or more, and if the visible light transmittance is 80% or more, the EUV transmittance can be adjusted to 95% or more.

[0023] Furthermore, the visible light transmittance of a pellicle film is correlated with the thickness of the pellicle film, and the thinner the pellicle film, the higher the visible light transmittance. On the other hand, the thinner the pellicle film, the more likely it is to deform or break.

[0024] Since the visible light transmittance is 85% or less, it is believed that the pellicle film has a certain thickness, thereby suppressing the amount of deformation of the pellicle film. As a result, the mechanical strength of the pellicle film is ensured. Furthermore, in the pellicle film according to this embodiment, since the standard deviation of the visible light transmittance calculated by the above formula (Equation 1) is 0.56% or less, it is believed that light transmits nearly uniformly over the entire surface of the pellicle film, at least in the range where the visible light transmittance is measured. As a result, variation in the EUV transmittance of the pellicle film is suppressed. Furthermore, the fact that visible light transmits nearly uniformly over the entire surface of the pellicle film, at least in the range where the visible light transmittance of the pellicle film is measured, is believed to mean that the pellicle film has a nearly uniform thickness over the entire surface. Therefore, since the pellicle membrane of this embodiment has a visible light transmittance calculated using the above formula (Equation 1) with a standard deviation of 0.56% or less, it is believed that the amount of deformation of the pellicle membrane can be reduced compared to pellicle membranes having the same visible light transmittance but a standard deviation of the visible light transmittance that exceeds 0.56%.

[0025] The visible light transmittance of the pellicle film according to this embodiment is a value measured based on the above (1), (2), and (3), and a small standard deviation of the visible light transmittance indicates that the intrinsic variation in the transmittance of the pellicle film is small. In other words, according to the method for measuring the visible light transmittance and the standard deviation of the visible light transmittance of the pellicle film according to this embodiment, which will be described later, it is possible to directly evaluate the visible light transmittance rather than a value obtained by reflection measurement, and therefore it can be used as an index of the intrinsic variation in the EUV transmittance of the pellicle film.

[0026] Referring now to FIG. 1, a cross-sectional view of a pellicle membrane according to this embodiment is schematically shown. The pellicle membrane 10 has a porous structure and contains carbon nanotubes. The pellicle membrane 10 has a first pellicle membrane surface 11 and a second pellicle membrane surface 12 opposite the first pellicle membrane surface 11. The pellicle membrane 10 is irradiated with white light having a wavelength of 400 nm or more and 750 nm or less from the second pellicle membrane surface 12. Based on an image of the pellicle membrane 10 in a light-transmitted state according to (1) above, an image at an imaging position in a bright state according to (2) above that does not include the pellicle membrane 10, and an image at an imaging position in a dark state according to (3) above that does not include the pellicle membrane 10, the visible light transmittance and its standard deviation calculated by the formula (Mathematical Formula 1) satisfy the specific numerical ranges described above.

[0027] In this specification, for the sake of convenience, the terms "first pellicle film surface" and "second pellicle film surface" are used to clarify the positional relationship between the surface placed on the imaging position and the surface to be imaged, and, in the pellicle described below, the positional relationship between the surface facing the support surface of the support and the surface on the opposite side. Therefore, in some cases, the terms "first pellicle film surface" and "second pellicle film surface" can be used interchangeably, and the terms "first pellicle film surface" and "second pellicle film surface" can be used interchangeably.

[0028] While an example of the pellicle membrane according to the present embodiment has been described above with reference to Figure 1, the pellicle membrane according to the present embodiment is not limited to this. The pellicle membrane according to the present embodiment can adopt various forms as long as the above-described effects can be obtained.

[0029] The carbon nanotubes contained in the pellicle film of this embodiment are not particularly limited, and are preferably at least one type selected from the group consisting of multi-walled carbon nanotubes (MWCNTs), few-walled carbon nanotubes (FWCNTs), double-walled carbon nanotubes (DWCNTs), and single-walled carbon nanotubes (SWCNTSs).

[0030] Carbon nanotubes can be obtained by known manufacturing methods such as arc discharge, laser ablation, and chemical vapor deposition.

[0031] The length of the carbon nanotube is preferably, for example, 0.1 μm or more and 1000 μm or less. The length of the carbon nanotubes is more preferably 0.5 μm or more, and even more preferably 1 μm or more. The length of the carbon nanotubes is more preferably 600 μm or less, and even more preferably 400 μm or less.

[0032] The cross-sectional diameter of the carbon nanotube is preferably 0.2 nm or more and 50 nm or less. The cross-sectional diameter of the carbon nanotube is more preferably 0.5 nm or more, and even more preferably 1 nm or more. The cross-sectional diameter of the carbon nanotube is more preferably 30 nm or less, and even more preferably 20 nm or less. In this specification, the cross-sectional diameter may be simply referred to as the diameter.

[0033] The pellicle membrane according to the present embodiment has a visible light transmittance calculated by the above formula (Equation 1) of 60% or more and 85% or less. From the viewpoint of the EUV transmittance of the pellicle membrane, the visible light transmittance calculated by the above formula (Equation 1) is preferably 65% ​​or more, more preferably 70% or more, even more preferably 75% or more, and even more preferably 80% or more. From the viewpoint of suppressing the deformation amount of the pellicle membrane, the visible light transmittance calculated by the formula (Equation 1) is preferably 85% or less, more preferably 84% or less, and even more preferably 83.5% or less. Here, the visible light transmittance calculated by the above formula (Equation 1) is the average value of the visible light transmittance. In this specification, the average value of the visible light transmittance refers to the average value of the visible light transmittance over the entire surface of the area of ​​the pellicle membrane where the visible light transmittance is measured.

[0034] The pellicle membrane according to the present embodiment has a visible light transmittance calculated by the above formula (Mathematical Formula 1) with a standard deviation of 0.56% or less. From the viewpoint of more easily suppressing variations in the EUV transmittance of the pellicle membrane and more easily suppressing deformation of the pellicle membrane, the standard deviation of the visible light transmittance is preferably 0.55% or less, more preferably 0.545% or less, and even more preferably 0.54% or less. The lower limit of the standard deviation of the visible light transmittance is preferably closer to 0%, but may be, for example, more than 0%, or may be 0.1% or more. Here, the standard deviation of the visible light transmittance is a numerical value calculated based on the visible light transmittance calculated by the above-mentioned mathematical formula (Mathematical Formula 1).

[0035] From the viewpoint of more easily suppressing variations in the EUV transmittance of the pellicle membrane and more easily suppressing deformation of the pellicle membrane, the pellicle membrane of this embodiment preferably has a visible light transmittance calculated by the above formula (Equation 1) in which the coefficient of variation of the visible light transmittance is 0.7 or less, more preferably 0.68 or less, and even more preferably 0.65 or less. The lower limit of the coefficient of variation of the visible light transmittance is preferably closer to 0, but may be, for example, greater than 0, or may be 0.1 or greater. Here, the coefficient of variation of the visible light transmittance is a numerical value calculated based on the visible light transmittance calculated by the mathematical formula (Mathematical Formula 1) and the standard deviation of the visible light transmittance described above. The coefficient of variation is found by dividing the standard deviation of the visible light transmittance by the visible light transmittance (i.e., the average value of the visible light transmittance).

[0036] (Method for measuring visible light transmittance and its standard deviation of pellicle membrane) The method for measuring the visible light transmittance and standard deviation of the visible light transmittance of a pellicle membrane having a porous structure according to this embodiment includes the following steps (S1) to (S7): The visible light transmittance of the pellicle membrane is calculated in step (S7) using the following mathematical formula (Mathematical Formula 1): By employing the following measurement method as a method for measuring the visible light transmittance and its standard deviation of the pellicle membrane, it becomes possible to directly evaluate the visible light transmittance and directly evaluate the variation in visible light transmittance, which can be used as an index of the essential variation in the EUV transmittance of the pellicle membrane.

[0037] Step (S1): A step of preparing a pellicle membrane containing carbon nanotubes and having a first pellicle membrane surface and a second pellicle membrane surface opposite to the first pellicle membrane surface. Step (S2): A step of placing the prepared pellicle membrane at an imaging position with the second pellicle membrane surface facing the imaging position. Step (S3): A step of irradiating the placed pellicle membrane with white light having a wavelength of 400 nm or more and 750 nm or less from the second pellicle membrane surface side, thereby transmitting the white light through the pellicle membrane. Step (S4): While irradiating the white light, an image is taken from the side of the first pellicle film that is not irradiated with the white light by an imaging means, and an area of ​​14,300 mm 2 A step of acquiring an image of the pellicle membrane in a light-transmitted state at 700,000 pixels or more. Step (S5): Under the condition of irradiating the white light, the imaging position not including the pellicle film is imaged, and an area of ​​14,300 mm 2 A process of acquiring an image of the bright state at an imaging position of 700,000 pixels or more. Step (S6): Without irradiating the white light, the imaging position not including the pellicle film is imaged in a light-shielded state, and an area of ​​14,300 mm 2 A process of acquiring an image of the imaging position in a dark state at 700,000 pixels or more. Step (S7): A step of calculating the visible light transmittance and the standard deviation of the visible light transmittance of the pellicle film based on the image of the pellicle film in the light-transmitting state, the image of the imaging position in the bright state, and the image of the imaging position in the dark state.

[0038] The visible light transmittance of the pellicle film is calculated by the following formula (Formula 1). T={(Tp-Td) / (Tb-Td)}×100…(Math 1) (In the above formula (Equation 1), T represents the visible light transmittance of the pellicle film, Tp represents a pixel value representing the transmission of the white light in the image of the pellicle film in the light-transmitting state, Tb represents a pixel value representing the transmission of the white light in the image of the bright state imaging position, and Td represents a pixel value when the white light is not irradiated in the image of the dark state imaging position.)

[0039] The image of the pellicle membrane in the light-transmitting state according to the above-mentioned (1) is preferably an image obtained by the operations of the steps (S3) and (S4). The image of the bright state imaging position according to the above-mentioned (2) is preferably an image obtained by the operation of the step (S5). The image of the dark state imaging position according to the above-mentioned (3) is preferably an image obtained by the operation of the step (S6).

[0040] Hereinafter, a measurement method for measuring the visible light transmittance and standard deviation of the visible light transmittance of a pellicle film according to this embodiment will be described with reference to the drawings. Figures 2A, 2B, and 2C are schematic diagrams illustrating the measurement method for measuring the visible light transmittance and standard deviation of the visible light transmittance of a pellicle film according to this embodiment, respectively.

[0041] The visible light transmittance and standard deviation of the visible light transmittance of the pellicle film according to this embodiment can be measured, for example, by a visible light transmittance measuring device 20 shown in FIGS. 2A, 2B, and 2C. Cross-sectional views of the visible light transmittance measuring device 20 are shown in FIGS. 2A, 2B, and 2C. As shown in FIGS. 2A, 2B, and 2C, the visible light transmittance measuring device 20 includes a camera 21 (an example of an imaging means), an illuminator 22 having a light source (not shown) capable of emitting white light 23, and a table 24 (an example of an imaging position) on which the pellicle film 10 can be placed. In the visible light transmittance measuring device 20, the light source (not shown) included in the illuminator 22 is a white LED (Light Emitting Diode) light source. The camera 21 is not particularly limited as long as it can capture an image with 700,000 pixels or more, as described below. The distance between the camera 21 and the table 24 is 14,300 mm , as described below. 2 There are no particular limitations on the camera 21 as long as it can capture an image with 700,000 pixels or more. The camera 21 may be, for example, a digital camera such as a digital single-lens reflex camera.

[0042] In step (S1), a pellicle membrane having a porous structure according to the present embodiment is first prepared. Specifically, the pellicle membrane prepared in step (S1) may be, for example, a pellicle membrane obtained by a preferred method for producing a pellicle membrane, which will be described later. As shown in FIG. 2A, in step (S1), a pellicle membrane 10 shown in FIG. 1 is prepared.

[0043] In step (S2), the pellicle film prepared in step (S1) is placed at an imaging position. As shown in FIG. 2A, in step (S2), the pellicle film 10 is placed on the table 24 with the second pellicle film surface 12 facing the table 24. The table 24 is made of a highly translucent transparent material such as glass, at least over the entire area where the pellicle film 10 is placed. Note that the pellicle film 10 may be placed with the first pellicle film surface 11 facing the table 24, rather than with the second pellicle film surface 12 facing the table 24. In this case, in step (S4) described below, the pellicle film 10 is imaged by the camera 21 from the side of the second pellicle film surface 12.

[0044] In step (S3), white light is irradiated from the side of the pellicle film placed at the imaging position, causing the white light to transmit through the pellicle film. The wavelength of the white light is 400 nm or more and 750 nm or less. As shown in FIG. 2A, white light 23 having a wavelength of 400 nm or more and 750 nm or less is emitted from a light source (not shown) provided inside the irradiator 22 and irradiated toward the table 24. When the white light 23 is irradiated toward the table 24, the white light 23 passes through the table 24. As the white light 23 passes through the table 24, the white light 23 is irradiated onto the pellicle film 10 placed on the table 24. The white light 23 irradiating the pellicle film 10 irradiates the second pellicle film surface 12 side of the pellicle film 10. When the white light 23 is irradiated from the second pellicle film surface 12 side of the pellicle film 10, the white light 23 passes through the pellicle film 10. At this time, the pellicle film 10 is in a light-transmitting state.

[0045] In step (S4), while irradiated with white light, an image is captured by an imaging means from the side not irradiated with white light, to obtain an image of the pellicle film in a light-transmitting state. As shown in FIG. 2A, the pellicle film 10 in a light-transmitting state is imaged by a camera 21 from the first pellicle film surface 11 side not irradiated with white light 23 while the pellicle film surface 12 side is still irradiated with white light 23. Then, an image of the surface of the captured pellicle film 10 is obtained. The captured image has an area of ​​14,300 mm 2and the image has 700,000 or more pixels. The pixel value of the acquired image is the pixel value Tp, which indicates that the white light 23 is transmitted in the image captured of the pellicle film 10 in a light-transmitting state, as shown in the above formula (Equation 1).

[0046] In step (S5), an image of the imaging position that does not include the pellicle film is captured under white light irradiation to obtain an image of the imaging position in a bright state. As shown in FIG. 2B, after the pellicle film 10 is removed from the table 24 under white light 23 irradiation, the table 24 is imaged by the camera 21. Then, an image of the table 24 in a bright state is obtained. The image of the table 24 does not include the pellicle film 10. The captured image has an area of ​​14,300 mm. 2 and the image has 700,000 pixels or more. As shown in the above formula (Equation 1), the pixel value of the acquired image is a pixel value Tb that indicates that white light 23 is transmitting in an image of table 24, which is an example of an imaging position in a bright state. The pixel value Tb is the maximum value of visible light transmittance.

[0047] In step (S6), the irradiation of the white light is stopped, and an image of the imaging position that does not include the pellicle film is captured in a light-shielded state, thereby obtaining an image of the imaging position in a dark state. As shown in FIG. 2C, the power to the irradiator 22 is turned off, and the irradiation of the white light 23 is stopped. Then, a light-blocking member 25 that blocks light is used to create a state in which almost no light enters the space in which the table 24 is being imaged. The light-blocking member 25 can be, for example, a blackout curtain. In this state, the table 24 is imaged by the camera 21. Then, an image of the table 24 in a dark state is obtained. The image of the table 24 that has been captured does not include the pellicle film 10. The captured image has an area of ​​14,300 mm 2 and the image has 700,000 pixels or more. As shown in the above formula (Equation 1), the pixel value of the acquired image is the pixel value Td when the table 24, which is an example of an imaging position in a dark state, is not irradiated with the white light 23. The pixel value Td is the minimum value of the visible light transmittance.

[0048] In step (S7), the visible light transmittance and the standard deviation of the visible light transmittance of the pellicle film are calculated based on the images acquired in steps (S4), (S5), and (S6). The visible light transmittance and the standard deviation of the visible light transmittance are calculated based on the acquired images using the following formula (Mathematical Formula 1) by an information processing device (not shown) composed of, for example, a personal computer, a server, or other computer electrically connected to the visible light transmittance measuring device 20. At this time, the coefficient of variation of the visible light transmittance can also be calculated.

[0049] T={(Tp-Td) / (Tb-Td)}×100…(Math 1) (In the above formula (Equation 1), T represents the visible light transmittance of the pellicle film, Tp represents a pixel value representing the transmission of the white light in the image of the pellicle film in the light-transmitting state, Tb represents a pixel value representing the transmission of the white light in the image of the bright state imaging position, and Td represents a pixel value when the white light is not irradiated in the image of the dark state imaging position.)

[0050] The pixel value Tb is the pixel value of an image taken at a bright imaging position where the pellicle film 10 is not included, and the pixel value Td is the pixel value of an image taken at a dark imaging position where the pellicle film 10 is not included.Therefore, the visible light transmittance T of the pellicle film calculated from the above formula (Equation 1) represents the visible light transmittance when the visible light transmittance in an image taken at a bright imaging position where the pellicle film 10 is not included is set to 100%.

[0051] In step (S7), when calculating the visible light transmittance of the pellicle film and the standard deviation of the visible light transmittance, a transmittance map of the pellicle film is created based on the images acquired in steps (S4), (S5), and (S6). Based on the created transmittance map of the pellicle film, the visible light transmittance (i.e., the average value of the visible light transmittance) and the standard deviation of the visible light transmittance are determined.

[0052] The pellicle membrane of this embodiment has a visible light transmittance of 60% or more and 85% or less, measured using the above-mentioned operating method, and the standard deviation of the visible light transmittance is 0.56% or less.

[0053] The thickness of the pellicle film according to this embodiment may be such that the visible light transmittance calculated by the above formula (Equation 1) is in the range of 60% or more and 85% or less, and the standard deviation of the visible light transmittance is 0.56% or less. By satisfying the standard deviation of the visible light transmittance of 0.56% or less, the pellicle film according to this embodiment has improved thickness uniformity in the range through which visible light passes through the pellicle film.

[0054] As described above, the pellicle film according to the present embodiment has a visible light transmittance of 60% or more, which allows the EUV transmittance to be adjusted to 93% or more. In one aspect of the pellicle film according to the present embodiment, when the visible light transmittance is, for example, approximately 80%, the maximum thickness of the pellicle film is, for example, 70 nm or less. Furthermore, in one aspect of the pellicle film according to the present embodiment, when the visible light transmittance is, for example, approximately 80%, the average thickness of the pellicle film is, for example, 50 nm or less. For example, in one aspect of the pellicle film according to the present embodiment, when the visible light transmittance is 70.8%, the average thickness of the pellicle film is approximately 47 nm. The thickness of the pellicle film according to the present embodiment can be measured using a scanning probe microscope. The thickness of the pellicle film according to the present embodiment is not particularly limited, as long as the visible light transmittance is in the range of 60% to 85% and the standard deviation of the visible light transmittance is 0.56% or less. The thickness of the pellicle membrane according to this embodiment may be, for example, 30 nm or more on average, or 35 nm or more on average, and may be, for example, 100 nm or less on average.

[0055] The weight per unit area of ​​the pellicle membrane is not particularly limited, and is 0.1 μg / cm 2 More than 20μg / cm 2The weight per unit area of ​​the pellicle membrane is preferably 0.5 μg / cm or less. 2 More preferably, it is 1 μg / cm or more. 2 The weight per unit area of ​​the pellicle membrane is more preferably 15 μg / cm or more. 2 More preferably, it is 10 μg / cm or less. 2 It is more preferable that the weight per unit area of ​​the pellicle membrane is, for example, 0.1 μg / cm or less. 2 More than 20μg / cm 2 If the thickness is below this, the pellicle membrane is more likely to ensure high EUV transmittance, the variation in EUV transmittance is more likely to be suppressed, and the amount of deformation is more likely to be kept small.

[0056] The pellicle membrane according to this embodiment is preferably a porous structure formed by the deposition of carbon nanotubes. The porous structure formed by the deposition of carbon nanotubes can be manufactured by an example of a preferred method for manufacturing a pellicle membrane, which will be described later. If the pellicle membrane is a porous structure formed by the deposition of carbon nanotubes, high EUV transmittance can be easily ensured, variations in EUV transmittance can be easily suppressed, and the amount of deformation can be easily kept small.

[0057] The pellicle film according to the present embodiment is preferably self-supporting from the viewpoint of improving transparency to exposure light. The term "self-supporting" refers to a film that is self-supporting by itself, and indicates that the pellicle film is a film that has self-supporting properties (also referred to as a self-supporting film). In other words, a self-supporting pellicle film is a film that can maintain its shape by itself, even without the presence of a substrate or the like.

[0058] There are no particular limitations on the means for adjusting the visible light transmittance calculated by the formula (1) to 60% or more and 85% or less, and the standard deviation of the visible light transmittance to 0.56% or less. Examples of such means include adjusting the dispersion conditions when dispersing carbon nanotubes and the centrifugation conditions when centrifuging the carbon nanotube dispersion in an example of a preferred method for producing a pellicle membrane described below.

[0059] (Method of manufacturing pellicle membrane) The method for producing a pellicle film according to this embodiment is not particularly limited, and various production methods can be applied, as long as the visible light transmittance and its standard deviation calculated by the above formula (Equation 1) satisfy the above-mentioned numerical range. Examples of the method for producing a pellicle film according to this embodiment include a filtration method (a method in which a pellicle film is obtained by filtering a carbon nanotube dispersion liquid through a filter and then peeling it off from the filter), a coating method (a method in which a carbon nanotube dispersion liquid is applied to a substrate and then peeled off from the substrate), and an etching method (a method in which a carbon nanotube film is formed on a wafer and then the wafer is etched to obtain a pellicle film).

[0060] As described above, the method for producing the pellicle membrane according to the present embodiment is not particularly limited. An example of a preferred method for producing the pellicle membrane according to the present embodiment is a production method including the following steps.

[0061] An example of a preferred method for manufacturing a pellicle membrane according to this embodiment comprises the steps of: (P1) dispersing carbon nanotubes to obtain a first dispersion of carbon nanotubes; (P2) dispersing the first dispersion by centrifugation to separate the carbon nanotube aggregates, and then collecting the supernatant to obtain a second dispersion of carbon nanotubes; (P3) precipitating and depositing the second dispersion of carbon nanotubes on an air-permeable member to obtain a mat-like carbon nanotube film on the air-permeable member; and (P4) removing the air-permeable member from the carbon nanotube film to obtain a pellicle membrane.

[0062] First, in step (P1), carbon nanotubes are dispersed in a liquid as a dispersion medium to prepare a first dispersion of carbon nanotubes in which the carbon nanotubes are dispersed in the liquid. The liquid may be a liquid containing water. The first dispersion of carbon nanotubes may contain only carbon nanotubes as a dispersoid. The carbon nanotube dispersion may contain, in addition to carbon nanotubes, various additives such as a dispersant that disperses the carbon nanotubes. Furthermore, in step (P1), the method for preparing the first dispersion is not particularly limited. The first dispersion can be prepared using various dispersion devices. For example, the first dispersion may be prepared using a wet atomization device. When the first dispersion is prepared using a wet atomization device, the conditions for the dispersion treatment using the wet atomization device may be, for example, a pressure of 50 MPa or more and 200 MPa or less, and the number of treatments may be one or more and 10 or less.

[0063] The weight of the carbon nanotubes per unit area is, for example, 0.1 μg / cm 2 as the amount of carbon nanotubes contained in the carbon nanotube film produced in step (P3). 2 More than 20μg / cm 2 The following ranges can be mentioned.

[0064] Next, in step (P2), the first dispersion of carbon nanotubes prepared in step (P1) is centrifuged using a centrifuge to separate the carbon nanotube aggregates. The supernatant liquid after the centrifugation is then collected to obtain a second dispersion of carbon nanotubes. The supernatant liquid contains carbon nanotubes. The conditions for the centrifugation are not particularly limited. From the viewpoint of separating the carbon nanotube aggregates, the conditions for the centrifugation are, for example, a relative centrifugal acceleration of 100 kG or more and a processing time of 1 hour or more.

[0065] Next, in step (P3), the supernatant liquid, which is the second dispersion liquid separated in step (P2), is allowed to settle and deposit on an air-permeable member. For example, the supernatant liquid separated in step (P2) is filtered through a filtration membrane as an air-permeable member, causing the carbon nanotubes to settle and deposit, forming a mat-like carbon nanotube membrane on the filtration membrane. Examples of the filtration membrane include a filtration membrane made of nonwoven fabric, and specifically, it is preferable to use a filtration membrane made of nonwoven fabric such as a membrane filter.

[0066] Next, in step (P4), the filtration membrane is removed from the mat-shaped carbon nanotube membrane to obtain a pellicle membrane containing carbon nanotubes. A drying step may be performed, if necessary, before or after removing the filtration membrane from the mat-shaped fiber membrane. Also, if necessary, both a drying step and an annealing step may be performed, or only an annealing step may be performed without a drying step. The pellicle membrane obtained through the above steps (P1) to (P4) is a self-supporting membrane.

[0067] [Pellicle] The pellicle of this embodiment comprises a pellicle membrane according to the embodiment described above, and a support having a frame and an opening surrounded by the frame, and supporting the pellicle membrane.

[0068] Hereinafter, the pellicle according to this embodiment will be described with reference to the drawings. It should be noted that in the description of the present specification, when drawings are referred to, some parts of the drawings are shown enlarged or reduced in size to facilitate the description.

[0069] FIG. 3 shows a plan view of pellicle 100 viewed from the surface on which pellicle membrane 10 is installed, and FIG. 4 shows a cross-sectional view of pellicle 100 shown in FIG. 3. Pellicle 100 comprises pellicle membrane 10 and a support 30 that supports pellicle membrane 10. Support 30 comprises a frame 31 and an opening 32 surrounded by frame 31, with opening 32 penetrating from one surface of support 30 to the other. Both frame 31 and opening 32 are formed in a rectangular shape, and all four corners of the outer shape of frame 31 are rounded. Frame 31 comprises a support surface 33 facing pellicle membrane 10. Pellicle membrane 10 is the pellicle membrane 10 shown in FIG. 1. The pellicle film 10 is formed in a rectangular shape and includes a first pellicle film surface 11 facing the support surface 33 of the support 30, and a second pellicle film surface 12 opposite the first pellicle film surface 11. The peripheral edge 13 of the pellicle film 10 is fixed to a part of the support surface 33 of the frame 31, and covers the opening 32 of the support 30.

[0070] The pellicle membrane according to the present embodiment described above is used as the pellicle membrane 10. Examples of materials that can be used for the support 30 include resin materials (polyethylene, etc.), metal materials (aluminum, aluminum alloys, magnesium alloys, stainless steel, titanium, etc.), ceramic materials (SiC, etc.), and fiber-reinforced plastic materials (carbon fiber-reinforced plastic, etc.).

[0071] While an example of a pellicle according to the present embodiment has been described above with reference to Figures 3 and 4, the pellicle according to the present embodiment is not limited to this. The pellicle according to the present embodiment may adopt various forms as long as the effects of the pellicle using the pellicle membrane according to the present embodiment described above can be obtained. The shape and dimensions of each part of each member constituting the pellicle according to the present embodiment may be determined, for example, according to the dimensions of the photomask (not shown) when the pellicle according to the present embodiment is used.

[0072] For example, the pellicle membrane 10 and the support 30 of the pellicle 100 shown in Figures 3 and 4 are both formed in a rectangular shape. The pellicle according to this embodiment is not limited to this, and may be formed in any desired shape, such as a circle, an ellipse, or a polygon.

[0073] 3 and 4, for example, the peripheral edge 13 of the pellicle membrane 10 is fixed to a portion of the support surface 33 of the support body 30. However, the pellicle 100 is not limited to this, and the peripheral edge 13 of the pellicle membrane 10 may be fixed to the entire surface of the support surface 33 of the support body 30.

[0074] 3 and 4, the pellicle membrane 10 and the support 30 may be fixed by providing an adhesive layer (not shown). The adhesive layer is a layer that is provided as needed. The material constituting the adhesive layer is not particularly limited, and may be, for example, various adhesives such as acrylic resin, epoxy resin, silicone resin, polyimide resin, and fluororesin, as well as carbon nanotubes.

[0075] (Method of manufacturing a pellicle) A preferred example of a method for manufacturing a pellicle according to the present embodiment includes the steps of: preparing a pellicle membrane according to the present embodiment; preparing a support having a frame and an opening surrounded by the frame and supporting the pellicle membrane; and providing the pellicle membrane on the support so as to cover the opening and be supported by the support surface of the frame. The manufacturing method may optionally include the step of providing an adhesive layer on at least a portion of the support surface of the frame.

[0076] The step of preparing a pellicle membrane according to this embodiment may involve preparing a pellicle membrane according to the above-described embodiment. The step of preparing a support may involve preparing a support formed into the desired shape using the material constituting the support described above by a known method. The step of providing a pellicle membrane may involve covering the opening and installing the pellicle membrane by a known method so that it is supported by the support surface of the frame. When an adhesive layer is provided on at least a portion of the support surface of the frame, the pellicle membrane is installed so that it is supported by the support surface of the frame via the adhesive layer. When various adhesives are used for the adhesive layer, the step of providing the adhesive layer involves applying an adhesive to the support surface to provide an adhesive-containing adhesive layer. When carbon nanotubes are used for the adhesive layer, the step of providing the adhesive layer may involve, for example, applying a carbon nanotube dispersion to the support surface and drying it to provide an adhesive layer containing carbon nanotubes.

[0077] The pellicle according to this embodiment is used, for example, by being placed above the photomask at a distance from the photomask so that the first pellicle film surface faces the photomask. By using the pellicle according to this embodiment, adhesion of foreign matter to the photomask is suppressed. Furthermore, since the pellicle according to this embodiment uses the pellicle film according to this embodiment described above, variation in EUV transmittance is suppressed while ensuring high EUV transmittance. Furthermore, the pellicle film according to this embodiment has a small amount of deformation and excellent mechanical strength, so breakage during installation and transportation of the pellicle is suppressed.

[0078] The present invention is not limited to the above-described embodiment, and includes modifications and improvements within the scope of achieving the object of the present invention. [Example]

[0079] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0080] [Example 1] <Fabrication of pellicle membrane> Carbon nanotubes (hereinafter referred to as CNTs) having a diameter of 0.2 nm or more and 50 nm or less and a length of 1 μm or more and 250 μm or less were prepared. The prepared CNTs were weighed so that the concentration of CNTs in the first dispersion before dilution was 0.02 mass%. In addition, a surfactant was weighed as a dispersant so that the concentration of CNTs in the first dispersion before dilution was 0.2 mass%. The weighed CNTs and the weighed surfactant were put into water, and the CNTs were dispersed in water using a wet atomizer. The dispersion conditions were a pressure of 70 MPa and three treatments. The mixture was then diluted to a CNT concentration of 1 ppm to prepare a first CNT dispersion. Next, the first CNT dispersion was collected so that the mass of CNTs (referred to as CNT amount in Table 1) was the value shown in Table 1 as the amount of CNT contained in the pellicle membrane.

[0081] Next, the first CNT dispersion was centrifuged using a centrifuge at a relative centrifugal acceleration of 100 kG for 2 hours to separate the CNT aggregates. After centrifugation, the supernatant was collected. This supernatant was used as the second CNT dispersion. Next, the second CNT dispersion was filtered through a membrane filter to form a mat-like CNT film on the membrane filter. The mat-like CNT film was then peeled off from the membrane filter. The CNT film was heat-treated at 650°C for 30 minutes to produce a pellicle film containing CNT. The pellicle film was a self-supporting film.

[0082] [Evaluation of pellicle membrane] <Measurement of visible light transmittance> From the obtained pellicle film, a transmittance map of the pellicle film was created according to the above-mentioned steps (S1) to (S7) using the visible light transmittance measuring device 20 shown in Figures 2A, 2B, and 2C, and the average value of the visible light transmittance was calculated using the above-mentioned formula (Equation 1) based on the created transmittance map of the pellicle film. A mirrorless camera (Canon Inc., "EOS R5") was used as the imaging means used in the above-mentioned steps (S1) to (S7). In addition, the standard deviation of the visible light transmittance and the coefficient of variation of the visible light transmittance were calculated from the obtained average value of the visible light transmittance. Note that the images obtained in the above-mentioned steps (S4), (S5), and (S6) were taken from an area of ​​14,300 mm 2 The image has 700,000 pixels. In Table 1, the average value is represented as AVE, the standard deviation as SD, and the coefficient of variation as CV.

[0083] <Deformation amount of pellicle membrane> The deformation of the pellicle membrane was measured using a measuring device equipped with a chamber having a partially open opening, a pressure sensor disposed inside the chamber, a holder for holding a sample at the opening of the chamber, and a laser displacement meter. The pellicle membrane obtained in each example was held in the holder, and nitrogen gas was introduced into the chamber at a pressure of 2 Pa to deform the pellicle membrane held in the holder of the chamber. The deformation of the pellicle membrane was measured using the laser displacement meter.

[0084] [Examples 2 and 3] A pellicle membrane of each example was produced in the same manner as in Example 1, except that the mass of CNT contained in the pellicle membrane was changed according to Table 1, and the pellicle membrane was evaluated.

[0085] [Comparative Examples 1 and 2] Pellicle membranes of Comparative Examples 1 and 2 were prepared in the same manner as Example 1, except that the mass of CNTs contained in the pellicle membrane was changed according to Table 1 and centrifugal separation was not performed, and the pellicle membranes were evaluated.

[0086] [Table 1]

[0087] From the above results, it can be seen that the pellicle films of each Example, in which the visible light transmittance calculated by the above formula (Equation 1) is 60% or more and 85% or less, and the standard deviation of the visible light transmittance is 0.56% or less, have small standard deviations and coefficients of variation of the visible light transmittance, and small deformation amounts of the pellicle film, even though the average visible light transmittance is similar to that of the pellicle films of each Comparative Example. Furthermore, the pellicle films of each Example, despite containing a relatively large amount of CNTs, have high visible light transmittance and small standard deviations and coefficients of variation of the visible light transmittance. Furthermore, the pellicle films of each Example have smaller deformation amounts than the pellicle films of each Comparative Example, resulting in improved mechanical strength. Therefore, the results obtained with the pellicle films of each Example indicate that the pellicle films have a high CNT content, excellent light transmittance, and improved mechanical strength while ensuring suppression of variation in light transmittance.

[0088] Therefore, according to the present embodiment, a pellicle membrane that ensures high EUV transmittance while suppressing variation in EUV transmittance and exhibiting small deformation, and a pellicle using the pellicle membrane are provided. Furthermore, according to the present embodiment, a method for measuring the visible light transmittance (average value) and standard deviation of the visible light transmittance of a pellicle membrane, which can be used as an index of the intrinsic variation in EUV transmittance of the pellicle membrane, is provided. Furthermore, according to the present embodiment, a method for measuring the coefficient of variation of the visible light transmittance of a pellicle membrane, which can be used as an index of the intrinsic variation in EUV transmittance of the pellicle membrane, is also provided. [Explanation of symbols]

[0089] 10...pellicle film, 11...first pellicle film surface, 12...second pellicle film surface, 13...periphery, 20...visible light transmittance measuring device, 21...camera, 22...illuminator, 23...white light, 24...table, 25...light-shielding member, 30...support, 31...frame, 32...opening, 33...support surface, 100...pellicle.

Claims

1. A pellicle membrane having a porous structure, the pellicle membrane comprises carbon nanotubes; The pellicle membrane has a first pellicle membrane surface and a second pellicle membrane surface opposite to the first pellicle membrane surface, (1) The second pellicle film surface side was placed at an imaging position, and white light with a wavelength of 400 nm or more and 750 nm or less was irradiated from the second pellicle film surface side. The image was taken from the first pellicle film surface side. The area was 14,300 mm ２ An image of a pellicle membrane in a light-transmitting state at 700,000 pixels or more; (2) An image of the imaging position in a bright state at or above the pixel of the area, obtained by imaging the imaging position that does not include the pellicle film under irradiation with the white light; and (3) Based on an image of the imaging position in a dark state at or above the pixel of the area, which is obtained by imaging the imaging position that does not include the pellicle film in a light-shielded state, The visible light transmittance calculated by the following formula (Mathematical Formula 1) is 60% or more and 85% or less, and the standard deviation of the visible light transmittance is 0.56% or less. Pellicle membrane. T={(Tp-Td) / (Tb-Td)}×100...(Math. 1) (In the above formula (Equation 1), T represents the visible light transmittance of the pellicle film, Tp represents a pixel value representing the transmission of the white light in the image of the pellicle film in the light-transmitting state, Tb represents a pixel value representing the transmission of the white light in the image of the bright state imaging position, and Td represents a pixel value when the white light is not irradiated in the image of the dark state imaging position.)

2. The pellicle membrane according to claim 1, The coefficient of variation of the visible light transmittance is 0.68 or less. Pellicle membrane.

3. The pellicle membrane according to claim 1 or 2, The length of the carbon nanotube is 0.1 μm or more and 1000 μm or less. Pellicle membrane.

4. The pellicle membrane according to claim 1 or 2, The cross-sectional diameter of the carbon nanotube is 0.2 nm or more and 50 nm or less. Pellicle membrane.

5. The pellicle membrane according to claim 1 or 2, have independence, Pellicle membrane.

6. The pellicle membrane according to claim 1 or 2, A support having a frame and an opening surrounded by the frame, and supporting the pellicle membrane; Equipped with Pellicle.

7. A method for measuring the visible light transmittance and standard deviation of the visible light transmittance of a pellicle film having a porous structure, comprising: providing a pellicle membrane including carbon nanotubes and having a first pellicle membrane surface and a second pellicle membrane surface opposite the first pellicle membrane surface; placing the prepared pellicle membrane at the imaging position with the second pellicle membrane surface facing the imaging position; a step of irradiating the placed pellicle film with white light having a wavelength of 400 nm or more and 750 nm or less from the second pellicle film surface side to transmit the white light through the pellicle film; In a state where the white light is irradiated, an image is taken by an imaging means from the side of the first pellicle film that is not irradiated with the white light, and an area of ​​14,300 mm ２ Acquiring an image of the pellicle membrane in a light-transmitting state at 700,000 pixels or more; With the white light irradiated, the imaging position not including the pellicle film was imaged, and an area of ​​14,300 mm ２ acquiring an image of a bright state at an imaging position of 700,000 pixels or more; The white light was not irradiated and the imaging position not including the pellicle film was imaged in a light-shielded state, and an area of ​​14,300 mm ２ acquiring an image of an imaging position in a dark state at 700,000 pixels or more; Calculating the visible light transmittance and the standard deviation of the visible light transmittance of the pellicle film based on the image of the pellicle film in the light-transmitting state, the image of the image capturing position in the bright state, and the image of the image capturing position in the dark state; Equipped with The visible light transmittance of the pellicle film is calculated by the following formula (Formula 1): Measurement method. T={(Tp-Td) / (Tb-Td)}×100...(Math. 1) (In the above formula (Equation 1), T represents the visible light transmittance of the pellicle film, Tp represents a pixel value representing the transmission of the white light in the image of the pellicle film in the light-transmitting state, Tb represents a pixel value representing the transmission of the white light in the image of the bright state imaging position, and Td represents a pixel value when the white light is not irradiated in the image of the dark state imaging position.)

Images