WO2014142125A1 - Pellicle film, and pellicle - Google Patents

Pellicle film, and pellicle Download PDF

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Publication number
WO2014142125A1
WO2014142125A1 PCT/JP2014/056346 JP2014056346W WO2014142125A1 WO 2014142125 A1 WO2014142125 A1 WO 2014142125A1 JP 2014056346 W JP2014056346 W JP 2014056346W WO 2014142125 A1 WO2014142125 A1 WO 2014142125A1
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film
pellicle
carbon
pore
membrane
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PCT/JP2014/056346
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French (fr)
Japanese (ja)
Inventor
宮下　憲和
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旭化成イーマテリアルズ株式会社
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Priority to JP2015505491A priority Critical patent/JP6084681B2/en
Priority to KR1020157024765A priority patent/KR101699655B1/en
Priority to CN201480015635.7A priority patent/CN105051604B/en
Publication of WO2014142125A1 publication Critical patent/WO2014142125A1/en

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/62—Pellicles, e.g. pellicle assemblies, e.g. having membrane on support frame; Preparation thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02—Inorganic material
    • B01D71/021—Carbon

Definitions

  • the present invention relates to a pellicle film for lithography using extreme ultraviolet light and a pellicle provided with the pellicle film.
  • a technique that has contributed to the high integration of this semiconductor integrated circuit is an exposure technique called optical lithography.
  • optical lithography the minimum line width of the wiring of the semiconductor integrated circuit is determined by the resolution, and the obtained resolution is in accordance with the Rayleigh equation, the aperture of the exposure optical system, the apparatus constant called the K1 factor of the exposure apparatus, and the exposure wavelength ⁇ ( Hereinafter, it is simply described as ⁇ ).
  • EUV lithography using ⁇ 6 to 14 nm of extreme ultraviolet light (hereinafter also referred to as EUV (Extreme Ultra Violet) light) called the EUV region is the most promising. It is thought that.
  • the EUV lithography uses the reflection reduction projection exposure technique, and all the components of the exposure apparatus including the EUV mask are arranged in a vacuum.
  • the first film structure is made of an element having a low extinction coefficient k (hereinafter also simply referred to as k) with respect to EUV light, such as carbon nanotubes (Carbon Nano Tube: CNT), etc. It is grown at intervals of several tens of nm and a height of several ⁇ m (see, for example, Patent Document 1).
  • the third film structure is an element having low k with respect to EUV light (silicon (Si), ruthenium (Ru), iridium (Ir), gold (Au), rhenium (Rh), carbon (C), etc.), or Using a compound (aluminum nitride (AlN), silicon nitride (SiN), silicon carbide (SiC), etc.) and a single-layer or multi-layer flat film having a film thickness of 30 to 300 nm, and openings such as rectangular and honeycomb-shaped A composite membrane in which a so-called grid or mesh membrane (hereinafter also referred to as a support membrane) having a wire diameter of several tens of ⁇ m and a cycle of lines of several hundred ⁇ m to several mm is joined (hereinafter also referred to as a support membrane) (for example, see Patent Documents 3 to 5 and Non-Patent Document 2).
  • an airgel film made of an element (Si, Ru, C, etc.) having a low k for EUV light is used as a pellicle film for EUV.
  • the airgel membrane is a sponge-like porous material containing a large number of micropores, mesopores, and macropores having an apparent density of several tens -3 to several tens -1 g / cm 3 , including air of 90.0 to 99.8%. It is a membrane.
  • the film thickness is about 1.0 to 10.0 ⁇ m. It is said that a film having sufficient film strength and high transmittance for EUV light can be obtained without a film (see, for example, Patent Documents 6 and 7).
  • This film structure has the following features: (1) Absorption of substances in the EUV region is highly dependent on the type of element and density of the substance, and (2) a foam structure (porous film) that allows Rayleigh scattering. In this way, attention is paid to securing the film thickness and increasing the film strength.
  • a pellicle film for EUV light having a high EUV light transmittance is obtained by silicon aerogel (Si airgel) produced by electrochemically dissolving Si using a solution containing hydrogen fluoride HF as a main component.
  • a pellicle film for EUV having high oxidation resistance can be obtained by using a metal foam aerogel prepared by irradiating a hydrogel containing a transition metal ion such as a noble metal or Ru with ⁇ rays to deposit metal nanoparticles. It is said that.
  • Patent Document 7 shows an attempt to realize this film structure with CNTs.
  • the CNT itself is used as a pellicle film for EUV by forming a film having a thickness of 1.0 to 5.0 nm by some method.
  • the apparent density of the CNT film is 1.5 ⁇ 10 ⁇ 3 to 0.5 g / cm 3 , a film structure similar to an airgel can be obtained.
  • the first film structure uses C as an element having a low k
  • the dust-proof protective film is in direct contact with the EUV mask surface, and the focus of the mask surface and a part of the pellicle film is Since they overlap, there is a possibility that the performance as a pellicle cannot be exhibited.
  • the structure control of CNTs is extremely difficult, and the production cost may increase. Therefore, the first film structure is not realistic.
  • the third film structure is an effective configuration for securing the film strength, and enables the film thickness to be reduced.
  • the support film itself acts as an obstacle and a limited visual field for the incident light to the EUV mask and the reflected light from the EUV mask, and the transmittance is reduced by about 30 to 60% compared to the transmittance of the flat film alone. It will be.
  • a material other than carbon C is used as the material of the pellicle film, there may be a problem of contamination particles at the time of breakage.
  • the fourth film structure has an advantage in that not only the high transmittance to EUV light is ensured, but also the restrictions on the film thickness are greatly improved as compared with the second film structure and the third film structure. is there.
  • the EUV pellicle film disclosed in Patent Document 6 has the following problems. That is, as in the third film structure, when an airgel film made of an element other than C is used as an EUV pellicle film, it is difficult to remove contamination if the EUV pellicle film is damaged for some reason such as impact. The problem of becoming particles can arise.
  • CNT uses a large amount of a metal catalyst such as iron Fe, cobalt Co, nickel Ni or the like having a high extinction coefficient in the production process. Therefore, the CNT inevitably contains a large amount of impurities. It becomes a large carbon film, and high transmittance cannot be obtained. Further, when the impurities are removed in order to use only a carbon film having a low extinction coefficient, there is a problem that the productivity is lowered and the manufacturing cost is extremely increased.
  • a metal catalyst such as iron Fe, cobalt Co, nickel Ni or the like having a high extinction coefficient in the production process. Therefore, the CNT inevitably contains a large amount of impurities. It becomes a large carbon film, and high transmittance cannot be obtained. Further, when the impurities are removed in order to use only a carbon film having a low extinction coefficient, there is a problem that the productivity is lowered and the manufacturing cost is extremely increased.
  • the present invention provides a pellicle film and a pellicle that have high transparency to EUV light, have practically sufficient physical strength and durability, can easily remove film fragments, and are excellent in productivity. Objective.
  • the present inventor made a general-purpose carbon pellicle film material so that part of the film was damaged and adhered to the EUV mask surface. Even in this case, it is possible to easily remove the porous film having a pore diameter / pore diameter distribution and an apparent density that can be used for a pellicle at a low cost with high productivity. I found out that I can do it.
  • the pellicle film according to one aspect of the present invention is composed of a carbon porous film, and the film thickness D is 100 nm to 63 ⁇ m.
  • the transmittance T when the extreme ultraviolet light having the wavelength of 13.5 nm passes once is 84% or more, and the fineness of the carbon porous membrane when the extreme ultraviolet light passes once
  • the scattering amount ⁇ due to the holes may be 10% or less.
  • the apparent density obtained by dividing the mass by the volume in the porous carbon membrane may be 1.0 ⁇ 10 ⁇ 3 to 2.1 g / cm 3 .
  • the wavelength ⁇ of extreme ultraviolet light is 13.5 nm
  • the density W of graphite is 2.25 g / cm 3
  • the apparent density (g / cm 3 ) of the porous carbon film is ⁇
  • the film thickness is D ( nm)
  • the carbon porous membrane may have structural parameters satisfying the following formulas (1) to (5).
  • the wavelength ⁇ of extreme ultraviolet light is 13.5 nm
  • the density W of graphite is 2.25 g / cm 3
  • the apparent density (g / cm 3 ) of the porous carbon film is ⁇
  • the carbon porous membrane may have structural parameters satisfying the following formulas (6) to (9).
  • ⁇ ⁇ 30 ( ⁇ : pore size parameter) (6) ⁇ / d ⁇ 81 ( ⁇ : exposure wavelength (nm)) (7) 0.08 g / cm 3 ⁇ ⁇ 0.7 g / cm 3 (8)
  • D 100 ⁇ D ⁇ 850 (9)
  • a pellicle according to another aspect of the present invention includes the pellicle film described above and a frame to which the pellicle film is attached.
  • the frame may be provided with a groove in which a mask adhesive for bonding to the lithography mask is disposed on the surface opposite to the surface to which the pellicle film is attached.
  • the frame may be provided with an electromagnet for bonding to the lithography mask on the surface opposite to the surface on which the pellicle film is supported.
  • the present invention has high transmittance to EUV light, has practically sufficient physical strength and durability, can easily remove film fragments, and has excellent productivity.
  • (A) is a graph which shows the relationship between an extinction coefficient, a transmittance
  • (b) is a graph which shows the relationship between a refractive index, a transmittance
  • the reference value of the present embodiment indicates three physical property values of transmittance, scattering amount, and film thickness of a pellicle film that is preferable for achieving the object of the present embodiment.
  • the transmittance T of the pellicle film (hereinafter also referred to as T, the unit is%) is preferably 70% or more of the reflectance of a single reflector used in EUV lithography, and is used as a reference value for T.
  • EUV Extreme Ultra Violet
  • T3 transmittance standard
  • the amount of scattering (hereinafter also referred to as ⁇ , the unit is%) is not only small when T is small, but also the blur of the circuit image on the EUV mask surface during exposure. Is generated. Therefore, it is desired that the scattering amount is as small as possible, but there is no clear reference value.
  • the upper limit of the amount of scattering considered to be a preferable range when passing through the pellicle film once is defined as the “scattering amount reference value”, and the reference values of 10%, 5%, and 1% are respectively used as the first scattering. These are referred to as an amount reference ( ⁇ 1), a second scattering amount reference ( ⁇ 2), and a third scattering amount reference ( ⁇ 3).
  • the amount of scattering it is considered that the amount of scattering when the pellicle film covering the EUV mask surface is passed twice in a reciprocating manner is approximately twice the amount of scattering when passing once.
  • the film thickness of the pellicle film (hereinafter also referred to as D, the unit is nm) has a great influence on the film strength (bending rigidity of the film) and the ease of handling of the film.
  • D is unavoidably set to 50 to 100 nm in order to obtain a T of 70% or more when passing through the pellicle film twice.
  • D 100 nm or more is set as the minimum necessary film thickness of the present embodiment.
  • the film thickness D is preferably 300 nm or more, more preferably 500 nm or more.
  • the reference value for D is hereinafter referred to as “film thickness reference value”, and the standards of 100 nm, 300 nm, and 500 nm are respectively referred to as the first film thickness standard (D1), the second film thickness standard (D2), and the third film thickness standard ( D3).
  • the pellicle film of this embodiment is composed of a carbon porous film, and the thickness D of the pellicle film is 100 nm to 63 ⁇ m.
  • the pellicle film of this embodiment preferably has a specific structure described later.
  • the premise, the structural model of the carbon porous film, and each structural parameter used for defining the structure of the pellicle film will be described.
  • An actual carbon porous membrane has a monodisperse pore structure (a structure model in which the pore diameter, wall thickness or column thickness, shape, etc. of the pores are the same and the aggregate state of such pores is uniform. It has a polydispersed structure in which various pores are mixed.
  • the carbon porous film actually obtained is approximated to a carbon porous film composed of monodispersed cubic shell-shaped or cubic frame-shaped pores as described later (hereinafter, respectively).
  • a cubic wall group pore model and a cubic axis group pore model are sequentially referred to as a cubic wall group pore model and a cubic axis group pore model), and the structure thereof can be defined by structural parameters.
  • the carbon constituting the pore wall or column of the actual carbon porous film is not all formed of graphite crystals, but in this embodiment, the graphite microcrystals aggregate in a non-oriented manner. It is assumed that it is formed of a polycrystalline body. If the crystallinity of the carbon is low and the density is less than 2.25 g / cm 3 , the wall thickness or column thickness d, or the substantial wall thickness dN or column thickness dN, as will be described later in [Appendix]. 1/2 can be increased depending on the optical constant (particularly k) of the carbon at that density.
  • a structure in which N pieces of cubic frame-shaped pores (pore diameter L) are stacked in the thickness direction is referred to as a cubic wall group pore model and a cubic axis group pore model, respectively. It is assumed that the layers in which the cubes are spread are stacked while being shifted in the thickness direction so that the apexes of the four corners of each cube are located in the center of the surface of the adjacent cube in the thickness direction.
  • L0 L + d (10) between L, L0, d, film thickness D, number N of pores, and pore size parameters ⁇ , d.
  • D N ⁇ + (N + 1) d (11) The relationship is established.
  • the structure of the porous membrane of the present embodiment can be defined using first and second structure parameters described later, and between each structure parameter, an equation ( 12) to (14) are related to the cubic axis pore model, and the relationships of (15) to (17) are established.
  • N ⁇ 1 + ⁇ (W ⁇ ) 1/3 / W 1/3 ⁇ + ⁇ D (W ⁇ ) 1/3 / ⁇ W 1/3 ⁇ (12)
  • d ⁇ ⁇ 1 + W 1/3 / (W ⁇ ) 1/3 ⁇ (13)
  • N 8.32 ⁇ 10 ⁇ 1 ⁇ D / ( ⁇ ) ⁇ -10.64 ⁇ + 3.54 ⁇ 10 ⁇ 2 ⁇ D 1/2 ⁇ + 7.65 ⁇ 10 ⁇ 1
  • d 7.90 ⁇ 10 -1 ⁇ ⁇ + 8.43 ⁇
  • Equations (11) and (14) use the first structure parameter group to represent the second structure parameter group, and Equations (12) and (13) represent the second structure parameter group. Represents the first structural parameter group.
  • Equations (11) and (17) use the first structure parameter group to represent the second structure parameter group, and Equations (15) and (16) represent the second structure parameter group. Represents the first structural parameter group.
  • the preferred structure of the carbon porous membrane in the present embodiment is determined according to the following three physical property values, T, ⁇ , and D reference values.
  • the structure of the carbon porous membrane includes the pore diameter (L) or the pore size parameter ( ⁇ ), the wall thickness or column thickness (d) forming the pores, and the number of pores stacked in the film thickness direction ( N) is defined as the first structural parameter group, and the apparent density of the carbon porous membrane described as L (or ⁇ ), D, and ⁇ (ap) or ⁇ is defined as the second structural parameter group, and these structural parameters are defined. It shall be possible.
  • the first structural parameter group is a microscopic structural parameter, which is convenient for defining the structure of the carbon porous membrane, but it is difficult to measure and observe directly and indirectly, and these are difficult in the manufacturing process. It is difficult to control and define the structure of the film using the value of.
  • the second structural parameter group is a macroscopic structural parameter, and it is relatively easy to measure and observe directly and indirectly, and it is easy to control the structure using these values in the manufacturing process. A microscopic structure cannot be uniquely determined without assuming a pore structure model from the value of.
  • Equation (12) to Equation (14) are obtained in the cubic wall-assembled pore model
  • Equation (15) is obtained in the cubic shaft-assembled pore model.
  • the contents are described using both structural parameter groups as appropriate, and when there is a contradiction between the two, the second structure in which the structure of the carbon porous membrane can be easily specified within a range that satisfies the reference value.
  • the parameter group is used with priority.
  • the pore diameter (L) is the peak peak radius r (peak) of the peak of the pore distribution curve obtained from the adsorption isotherm of the gas adsorption type pore distribution measurement method, and the maximum peak radius r (max) (pore L (peak) and L (max) are values obtained by doubling the values of the distribution radius and the pore distribution base (pointing to the larger pore radius value) (referred to as double values), respectively.
  • the unit is [nm]. Note that r (max) and L (max) are used when discussing the upper limit of each criterion of ⁇ , and otherwise L (peak) is L and r (peak) is r unless otherwise specified. Use.
  • r (max) is a logarithmic scale of r on the horizontal axis of the pore distribution diagram.
  • r (peak) is set as an alternative value for r (max).
  • a carbide sample is heated in vacuum at 200-250 ° C for 2-15 hours in advance, then nitrogen adsorption / desorption isothermal measurement at liquid nitrogen temperature is performed, and DH analysis is performed from the adsorption / desorption isotherm.
  • the pore distribution curve is obtained by the method or the BJH analysis method. In this embodiment, this method is used to determine the pore diameter.
  • the pore diameter can be substantially defined because the individual pores are separated by walls.
  • the individual pores are connected, and as shown in FIG. 4B, the values are strictly classified (virtual).
  • the pore wall thickness or column thickness (d) in the present embodiment delimits individual pores constituting the carbon porous membrane in the cubic wall set pore model (becomes a pore barrier). It is the average thickness of the carbon wall, and the thickness of the wall of the cubic wall set. In the cubic axis pore model, the average thickness of carbon rods (columns) that formally divide the pores that make up the carbon porous membrane, and the thickness of the cubic frame It is. The unit is [nm].
  • D can be obtained by taking a cross-sectional photograph of the porous film using a transmission electron microscope (TEM) or a scanning electron microscope (SEM) and processing the photograph.
  • TEM transmission electron microscope
  • SEM scanning electron microscope
  • the value of d is about 0. 335 nm is the lower limit of d.
  • the pore diameter is large (for example, ⁇ > 4) or when a large force is applied to the pellicle film, the wall strength or the column strength (film strength)
  • d can be brought close to 0.335 nm.
  • N The number of pores (N) is the number of pores having a pore diameter L in the film thickness direction.
  • N is a value calculated from ⁇ , ⁇ (ap), and D according to Equation (12) in the cubic wall group pore model and according to Equation (15) in the cubic axis group pore model.
  • N should be an integer of N ⁇ 1 in the definition of the word, but a positive real value is allowed.
  • the fractional part of the numerical value below the decimal point is considered to reflect the deviation from the pore structure model in which monodispersed cubic shell-like or cubic frame-like pores are neatly stacked.
  • the apparent density ⁇ (ap) is a density using the membrane volume when it is assumed that there are no pores inside the porous membrane, and the ratio between the membrane volume V and the membrane mass G obtained from the outer dimensions of the membrane. , G / V.
  • the arithmetic apparent density ⁇ is based on the pore structure model, in the present embodiment, according to the equation (14) for the cubic wall assembly pore model and the equation (17) for the cubic axis assembly pore model.
  • the unit is [g / cm 3 ].
  • the film thickness (D) is the thickness of a sheet, film, or film used in the usual sense.
  • the measurement of the thickness of this embodiment can be obtained as a value obtained by averaging 10 or more images of a porous film in a non-contact manner with an interval of 1 mm or more using an electron microscope (SEM).
  • SEM electron microscope
  • the unit is usually [nm], and [ ⁇ m] is also used as necessary.
  • the average pore shape of the porous membrane is described in Reference A, Hideki Matsuoka, Journal of Crystallographic Society, No. 41, 213-226 (1999), Keiko Nishikawa, Carbon, No. 191, 71-76 (2000), it can be obtained from the scattering intensity analysis in the Debye-Porod region of small angle X-ray scattering (SAXS). That is, when the logarithmic plot of the X-ray scattering intensity I as a function of the scattering vector s is a logarithmic slope of ⁇ 4, ⁇ 2, and ⁇ 1, the pore shape is spherical, disk-shaped, cylindrical, respectively.
  • SAXS small angle X-ray scattering
  • the technical point 1 is that the pellicle membrane is a porous membrane.
  • Mie's scattering theory Mie scattering itself is scattering by spherical particles, but qualitatively the shape is not limited
  • light scattering by spherical particles spherical pores
  • the diameter of the particles pores.
  • the particle size parameter ⁇ 2 ⁇ / ⁇
  • Rayleigh scattering occurs when ⁇ is sufficiently smaller than 1 ( ⁇ ⁇ 1).
  • ⁇ is almost 1 ( ⁇ 1), Mie scattering occurs, and when ⁇ is sufficiently larger than 1 ( ⁇ >> 1), geometric scattering occurs.
  • the graph which showed the relationship with the reflectance R is shown.
  • the graph shown in FIG. 1 is calculated using a “G-Solver grid analysis software tool (G-Solver)” commercially available from “Grating Solver Development Company”.
  • a region surrounded by a dotted line indicates a region k that can secure T ⁇ 84%.
  • T ⁇ T1 84% unless at least k is less than the order of 10 ⁇ 3. It can be seen that cannot be obtained.
  • the region surrounded by a dotted line indicates an n region where the reflectance R ⁇ 0.2%.
  • n 0.94 to 1.4, that is, ⁇ n ⁇ 0.04
  • the first advantage of using a porous film as the pellicle film is that the thickness limitation of the 50 to 100 nm film in the conventional Si single crystal flat film is greatly relaxed, and T is T1 or more and ⁇ is ⁇ 1 or less as described later. And D can be 100 nm or more (D1 or more), 300 nm or more (D2 or more), or 500 nm or more (D3 or more).
  • a second advantage of using a porous film as a pellicle film is that a corrugated cardboard-like porous wrapping paper material has a higher bending rigidity than a flat film-like paper board having the same weight and the same area.
  • the film has higher bending rigidity than a flat film (non-porous film) having the same weight and the same area.
  • the porous film of the present embodiment has a three-dimensional porous structure, so that the stress concentration is further increased. It can be said that the bending rigidity of the film is even higher.
  • the porous film of the present embodiment is used as a pellicle film, the degree of bending of the film by its own weight is small compared to a flat film of another material having the same area and weight.
  • n and k obtained by using the apparent density ⁇ of the porous film which is smaller than the density of the non-porous material (usually simply called the density or the true density), are the crystal / amorphous structure and its ratio. Assuming that does not change, the value can be regarded as the optical constant of the porous film having that ⁇ .
  • a flat film (non-porous film) having an apparent density ⁇ and an optical constant at the ⁇ is referred to as a porous film alternative flat film, various ⁇ s ignoring scattering by the pores for convenience.
  • the n and k of the porous membrane alternative flat membrane that can be obtained can be obtained from Non-Patent Document 1.
  • 3 is a graph showing the dependence of C of 3 on the wavelength ⁇ of n and k.
  • a second advantage of using carbon as the porous film is that the pellicle film can be easily removed even if it is damaged and adhered to the mask.
  • EUV Ultraviolet
  • a third advantage of using carbon as the porous film is that a porous film having a target pore diameter and film thickness can be easily produced by applying an existing carbon porous film manufacturing method. That is, as described in “2.2 Pellicle membrane manufacturing method of this embodiment”, a thin film is formed using a solution of an organic compound that causes a sol-gel transition, and a large amount of solvent is contained by the sol-gel method. By forming a hydrogel state and then drying and removing the solvent so that the structure is not crushed, an airgel film as a porous body containing a large amount of bubbles can be obtained.
  • the airgel membrane is carbonized to obtain a carbon porous membrane as a carbon aerogel, or a polymer raw material (organic compound) that immobilizes the structure in the molecular structure during the chemical reaction process or carbonization process and generates bubbles.
  • the film thickness can be easily controlled using a wet coating method in a non-vacuum environment such as spin coating, die coating, and gravure coating using a polymer solution, or silicon.
  • a rod-shaped material is thinly cut and polished to form a thin film, thereby enabling high-productivity manufacturing.
  • a fourth advantage of using carbon as the porous film is that it has excellent thermal characteristics and bending rigidity.
  • the melting point and thermal expansion coefficient of amorphous carbon (aC), graphite (gC) and Si are as follows. That is, the melting point under normal pressure is the highest among all elements, and a-C and g-C have no melting point, Si has 1414 ° C., and the heat resistance of carbon is excellent.
  • the coefficient of thermal expansion is 3.0 ⁇ 10 ⁇ 6 / K for aC , 3.2 ⁇ 10 ⁇ 6 / K for gC, and 3.9 ⁇ 10 ⁇ 6 / K for Si. Excellent dimensional stability.
  • the bending stiffness corresponding to the hardness (physical strength) of the film is proportional to the product of the Young's modulus and the cube of the film thickness D because the Poisson's ratio of carbon and Si is both about 0.2.
  • the Young's modulus of aC is 30 to 33 GPa and the Young's modulus of gC is 14 GPa, whereas the Young's modulus of Si is 130 to 190 GPa.
  • Si is superior to carbon, but in the present embodiment, it is actually a porous carbon film, and since the film thickness D can be made 2.5 to 5 times thicker than the Si flat film, The carbon porous membrane of this embodiment is considered to be larger.
  • the technical point 3 is that a carbon porous film that satisfies the problem can be defined using restricted structural parameters.
  • the optical constants n and k ( ⁇ 9.61 ⁇ 10 ⁇ 1 and 7.70 ⁇ 10 ⁇ 3 ) and ⁇ , respectively, of ⁇ 13.5 nm of carbon (2.25 g / cm 3 ) obtained from Non-Patent Document 1.
  • T is a value of dN 1/2 which is considered to correspond to a substantial thickness in the film thickness direction corresponding to dN of the cube wall set pore model.
  • ⁇ is a connected pore in the cubic axis pore model, and since ⁇ has only a formal meaning, ⁇ is regarded as 1 and has an influence in the form of dN 1/2 . That is, it means that there is no influence of the pore diameter.
  • Step 2 From the multiple regression equation shown in Step 1, qualitatively, it was possible to know the influence of each structural parameter group on T and ⁇ .
  • the values of the group ( ⁇ , D, ⁇ ) the values of N satisfying the reference values of Ti and ⁇ i at each ⁇ , d, N (Ti), N ( ⁇ i) are estimated, and further the formula (2 ) To obtain D values D (Ti) and D ( ⁇ i) that satisfy the respective reference values of T and ⁇ .
  • N (Ti), N ( ⁇ i), D (Ti), and D ( ⁇ i) mean the upper limit number of layers N max and the upper limit film thickness D max that satisfy the reference values of T and ⁇ , respectively. To do.
  • the ranges of the structural parameters ⁇ , N, d, ⁇ , and D satisfying the constraint conditions 1 to 4 as a carbon porous membrane that can be actually obtained are set in the present embodiment. A porous carbon membrane satisfying the problems is obtained.
  • Restriction 1 0.335 nm ⁇ d (41)
  • Restriction condition 2 1 ⁇ N (42)
  • Restriction condition 3 0.5 ⁇ ⁇ (43)
  • Restriction condition 4 1.0 ⁇ 10 ⁇ 3 g / cm 3 ⁇ ⁇ ⁇ 2.25 g / cm 3 (44)
  • Constraint conditions 1 and 2 are related to the microstructure parameters described in the definition of d and N, and are the premise of the calculation.
  • d is preferably 1.35 nm or more.
  • N is preferably 2 or more, and if the value is large, the cubic shell-like or cubic frame-like pores having different microstructure parameters in each pore structure model are within the range satisfying each reference value.
  • a laminated film structure in the film thickness direction can be considered.
  • Constraint condition 3 is a structural parameter common to both micro and macro, and the ⁇ value here indicates a value corresponding to L (peak) of the pore distribution. From the significance of this embodiment, the lower limit is set to 0.5.
  • the carbon porous membrane actually obtained contains pores having pore diameters smaller than the ⁇ value, and it is difficult to eliminate them. However, pores with small pore diameters are not preferable because they hardly contribute to the improvement of the film thickness of the carbon porous membrane, and only reduce the transmittance due to the lamination of the wall thickness. Therefore, it is preferable that the pore distribution has a sharp shape centered on L (peak).
  • the upper limit of ⁇ is obtained from step 2, but empirically L (max) ⁇ 1.5 ⁇ L (peak) to 3 ⁇ L (peak), corresponding to the average pore diameter in the carbon porous membrane If the upper limit [L (peak) / ⁇ ] of ⁇ is set to 1 / 1.5 to 1/3 of the upper limit of ⁇ obtained from step 2, the maximum pore diameter in the carbon porous membrane actually obtained is It is considered that it can be suppressed to the upper limit of ⁇ obtained from Step 2, and is preferable.
  • Constraint condition 4 is determined from the lower limit of the apparent density ⁇ actually obtained as carbon aerogel.
  • the reciprocals of ⁇ and ⁇ / d are related to the equation (5) in the cubic wall set pore model and the equation (8) in the cube axis set pore model.
  • ⁇ / d is an index of the strength of the individual pores by the structure of the term. Specifically, if the value is small ( ⁇ is large), the pores themselves are strong.
  • the upper limit value of D is the smallest in each pore structure model It was realized with ⁇ and the maximum ⁇ / d.
  • ⁇ 1.2 ⁇ 10 ⁇ 3 to 2.1 g / cm 3 .
  • Step 3 an example of a characteristic structure preferable as a pellicle film (provided that d ⁇ 1.35 nm) is shown.
  • each pore structure model is represented in the form of ⁇ , d [unit nm], D [unit nm], ⁇ [unit g / cm 3 ], ⁇ / d ⁇ in the ranges of the structural parameter group and the constraint condition values.
  • An example of the structure is described for each wavelength of EUV light.
  • ⁇ A1, B1, C11-C12, D1, E1 ⁇ - ⁇ A2, B1, C21-C22, D2, E2 ⁇ are the pore size parameters with the wall thickness or the column thickness d being the same B1 value. It means that the reference value of the present embodiment can be taken when ⁇ is in the range of A1 to A2 and the film thickness D is in the range of C11-C22 and C21-C22 corresponding to each ⁇ .
  • the characteristic structure 1 is an ideal structure as a pellicle film.
  • ⁇ , d, D, ⁇ , ⁇ / d ⁇ ⁇ 2 , 1.35, 500-835, 1.5 ⁇ 10 ⁇ 2 , 20 ⁇ ⁇ ⁇ 8, 1.35, 500-4659, 1.0 ⁇ 10 ⁇ 3 , 80 ⁇ , ⁇ 3 , 2.01, 500-677, 1.5 ⁇ 10 ⁇ 2 , 20 ⁇ - ⁇ 10, 2.01, 500-2635, 1.4 ⁇ 10 ⁇ 3 , 67 ⁇ , ⁇ 4, 2.7, 500-592, 1.5 ⁇ 10 ⁇ 2 , 20 ⁇ - ⁇ 15, 2.70, 500-2188, 1.6 ⁇ 10 ⁇ 3 , 75 ⁇ , ⁇ 6, 3 .35, 500-587, 1.0 ⁇ 10 ⁇ 2 , 24 ⁇ - ⁇ 20, 3.35, 500-1894, 1.0 ⁇ 10 ⁇ 3 , 81 ⁇ , ⁇ 8, 4.02, 500-542
  • a carbon porous membrane having the following structural parameters satisfies ⁇ ⁇ 1.0 ⁇ 10 ⁇ 2 g / cm 3 , and is more preferable from the viewpoint of membrane strength.
  • ⁇ , d, D, ⁇ , ⁇ / d ⁇ ⁇ 2, 1.35, 100-119, 3.1 ⁇ 10 ⁇ 1 , 20 ⁇ ⁇ ⁇ 8, 1.35, 111-210, 8.2 ⁇ 10 ⁇ 2 , 80 ⁇ , ⁇ 3, 2.01, 100-110, 3.0 ⁇ 10 ⁇ 1 , 20 ⁇ - ⁇ 8, 2.01, 112-143, 1.2 ⁇ 10 ⁇ 1 , 54 ⁇ , ⁇ 6, 2.70, 100-114, 2.1 ⁇ 10 ⁇ 1 , 30 ⁇
  • a porous carbon film having the following structural parameters, ⁇ ⁇ 1.0 ⁇ 10 ⁇ 2 g / cm 3, which is preferable from the viewpoint of film strength.
  • ⁇ , d, D, ⁇ , ⁇ / d ⁇ ⁇ 0.5, 1.35, 1588-1636, 1.7 ⁇ 10 ⁇ 1 , 5 ⁇ - ⁇ 2, 1.35, 5550-6359, 1 .5 ⁇ 10 ⁇ 2 , 20 ⁇ , ⁇ 0.5, 2.01, 776-799, 3.0 ⁇ 10 ⁇ 1 , 3.4 ⁇ - ⁇ 2, 2.01, 2564-2937, 3.1 ⁇ 10 ⁇ 2 , 13 ⁇ , ⁇ 1 , 2.70, 796-850, 1.7 ⁇ 10 ⁇ 1 , 5 ⁇ - ⁇ 4, 2.70, 2778-3632, 1.9 ⁇ 10 ⁇ 2 , 20 ⁇ , ⁇ 1, 3.35, 540-578, 2.3, 4 ⁇ - ⁇ 6, 3.35, 2687-3976, 1.0 ⁇ 10 ⁇ 2 , 24 ⁇ , ⁇ 2 , 4.02, 690 -789,1.0 ⁇ 10 -1, 67 ⁇ - ⁇ 6,4.02,1881-2784,1.5 ⁇ 10 -3,
  • the above shows an example of a characteristic structure preferable as a pellicle film, using each range of the value of the structural parameter group and the constraint condition.
  • An EUV pellicle film having a transmittance T of 84% or more, a scattering amount ⁇ of 10% or less, and a film thickness D of 100 nm or more can be shown.
  • the wavelength ⁇ of EUV light is 13.5 nm
  • the density W of graphite is 2.25 g / cm 3
  • the apparent density (g / cm 3 ) of the porous carbon film is
  • ⁇ and the film thickness are D (nm)
  • the carbon porous body film has the structural parameters of the following equations (1) to (5).
  • a pellicle film for EUV that satisfies the range may be preferable.
  • the pellicle membrane for EUV satisfies the range of the structural parameters of the following formulas (6) to (9) in the carbon porous membrane can do.
  • ⁇ ⁇ 30 ( ⁇ : pore size parameter) (6) ⁇ / d ⁇ 81 ( ⁇ : exposure wavelength (nm)) (7) 0.08 g / cm 3 ⁇ ⁇ ⁇ 0.7 g / cm 3 (8) D: 100 nm ⁇ D ⁇ 850 nm (9)
  • a characteristic structure preferable as a pellicle film for EUV can be shown using mathematical formulas corresponding to the exposure wavelength ⁇ and the approximate pore structure model under an appropriate calculation method.
  • the present embodiment is a pellicle film, which is composed of a porous carbon film, and from [Technical Point 3], the film thickness D of the pellicle film is A pellicle film having a thickness of 100 nm to 63 ⁇ m.
  • the first example is to prevent oxidation / reduction of the porous carbon film by light from a high-power EUV light source on one or both surfaces of the porous carbon film of the present embodiment.
  • Si, SiC, SiO 2 , Si 3 N 4 , Yttrium Y, Molybdenum Mo, Ru, Rhodium Rh, etc. within a range satisfying the target value of the subject of the present invention, such as a known sputtering method, vacuum deposition method, etc.
  • the method is to coat several nm.
  • Si is particularly preferred because it has a low extinction coefficient of EUV light, a refractive index close to 1.0, and reacts with carbon to form a SiC film having a few nm with excellent strength on the carbon film surface.
  • the carbon porous film of the present embodiment has a film thickness having high transparency and practically sufficient durability for EUV light, but when further film strength is required.
  • the mesh is used as a supporting film as in Patent Document 3, Patent Document 4, Patent Document 5, and Non-Patent Document 2 (materials are Si, Zr, Mo, titanium Ti Nickel nickel, aluminum Al, copper Cu, and their carbides are preferable from the viewpoint of having a small extinction coefficient and ⁇ n, and being easily available as a general-purpose product).
  • the transmittance is lowered by 10% or more by the support membrane (mesh having a mesh thickness of several tens of ⁇ m, a wire diameter constituting the mesh of several tens of ⁇ m, and a pore size of several hundred ⁇ m to several mm),
  • the transmittance T of the carbon porous membrane alone of the present invention is T2, T3. Note that the support film hardly affects the scattering amount ⁇ .
  • the transmittance T and scattering amount ⁇ of the present embodiment represented by the equations (19) to (40), the equations (1) to (5), and the equations (6) to (9) in [Technical Point 3].
  • the relational expression between the structural parameter group of the carbon porous membrane and the structural parameter group for obtaining the reference values of T, ⁇ , and D are EUV under (Premise 1) and (Premise 2).
  • FIG. 5 is a diagram showing a method for manufacturing a pellicle film.
  • the first method is to add a binder to fine carbon precursor particles or carbon particles that are about the same size to several tens of times the target pore size and do not melt or break during sintering and carbonization. This is a method of obtaining a porous carbon film having pores between the particles by sintering and carbonizing after film formation.
  • a solvated gel film for example, hydrogel
  • a solvated gel film for example, hydrogel
  • a sol-gel method A method of obtaining a carbon porous film as a carbon aerogel by obtaining aerogel film containing a large amount of bubbles by drying and removing only the solvent so that the solvation structure does not collapse, and finally carbonizing the aerogel film It is.
  • a chemical reaction or a carbonization reaction is performed using a raw material in which a structure is fixed in a molecular structure in a chemical reaction process or a carbonization process and bubbles are generated.
  • This is a method for obtaining a carbon porous membrane having pores of air bubbles or gaps. From the first method, it is relatively easy to control the particle size and produce a porous carbon membrane having a pore diameter of about 0.5 to 10 times the wavelength of EUV light, compared to other methods. It is difficult to obtain a low-density carbon porous film having an apparent density of 1.0 g / cm 3 or less.
  • the porous carbon membrane of this embodiment can be obtained by the second and third methods.
  • the carbon porous membrane of this embodiment applies the existing carbon porous membrane manufacturing technology as mentioned in the second advantage of [Technical Point 2]. However, these manufacturing techniques differ in two points, [Technical Point 4] and [Technical Point 5].
  • Technology point 4 is to introduce thin film deposition technology.
  • Technical point 4 is that the use of the porous carbon membrane of the present embodiment is a pellicle membrane that was not considered at all as an application of the existing porous carbon membrane, so that a film forming technology for obtaining a thin film is added. It is. That is, in the manufacturing method of the carbon porous membrane of this embodiment described later, a film forming step suitable for thinning (step A2, step B2, step AB2) and a coating liquid preparation step for obtaining a thin film (step) A1, process B1, and process AB1) are important technical points.
  • the composition, molecular weight, and temperature of the coating liquid are adjusted, the viscosity of the coating liquid is lowered, and the film thickness after film formation / drying can be applied to a film thickness of several tens to several hundreds of micrometers. Is preferred.
  • Film thickness after the carbonization is about 0.5 to 3 times the coating thickness in the fixing / drying process (process A3, process B3, process AB3) and carbonization process (process A4, process B4, process AB4) This is because the thickness becomes 100 nm to 63 ⁇ m.
  • the concentration of the solute that finally becomes carbonaceous in the coating solution may be reduced within the range of the manufacturing parameters described in Technical Point 5.
  • the coating solution is a polymer solution, it is preferable to lower the molecular weight to such an extent that the coating film does not break when it is peeled off from the base material at the time of coating after drying.
  • a coating method for obtaining a thin film it is preferable to use a wet coating method capable of thinly coating a low-viscosity coating solution, not a dry coating method typified by a vapor deposition method.
  • coating methods that are low in productivity such as spin coating, nozzle scan coating, and ink jet coating, but thin films such as bar coating, gravure coating, die coating, doctor coating, and kiss coating are advantageous.
  • a coating method with high productivity can be used by continuous coating called roll-to-roll.
  • it is possible to obtain a uniform thin film by adjusting the coating conditions such as coating speed, coating temperature, and coating time as well as adjusting and selecting the coating solution viscosity, composition and coating method appropriately. be able to.
  • the technical point 5 is a manufacturing parameter (the kind and molecular weight of the carbonaceous solute, the solution composition, the solution concentration) according to each manufacturing method.
  • the crosslinking catalyst species / dehalogenation species and their concentrations, drying conditions, carbonization conditions, etc.) are adjusted, and the details will be described below.
  • step A1 as the carbonaceous raw material, one or more monomers consisting of resorcinol (R), phenol, catechol, phloroglucinol and other polyhydroxy-benzene compounds, and formaldehyde ( F) and one or more monomers of furfural, and also as an alkali catalyst (Ca) for gelation (polymerization), potassium carbonate (K 2 CO 3 ), sodium carbonate (Na 2 CO 3 ), potassium hydrogen carbonate ( Any one or more of alkali metal carbonates such as KHCO 3 ) and sodium hydrogen carbonate (NaHCO 3 ) and alkali metal hydrogen carbonate are dissolved in water (Wa), and these are mixed to form coating solution A (RF viscosity). Liquid).
  • step A2 following step A1, the coating liquid A is coated on a release film or release substrate so that the film thickness after carbonization becomes 100 to 850 nm so that it can be easily peeled later (as described above). Bar coating, spin coating, etc.) / Film formation. At this time, the surroundings of the release film and the release substrate are hermetically sealed, the coating film does not flow out of the release film and the release substrate, and the solvent (water) evaporates and the composition of the coating liquid It is preferable to seal so that the region which becomes the membrane pores is not crushed.
  • step A3 subsequent to step A2, the temperature is raised stepwise from room temperature (20 ° C.) to 100 ° C. or allowed to stand for several days (1 to 14 days) to sufficiently gel (polymerize), A thin-film hydrogel film is obtained.
  • heating 50 to 100 ° C.
  • the heating temperature is preferably low.
  • the hydrogel film is peeled off from the release film or release substrate, and dried so that the pore diameter and shape can be more maintained, so that the solvent (water) in the hydrogel film is replaced with acetone or cyclohexane.
  • substitution in order to suppress changes in pore diameter and pore shape due to contact with the substitution liquid, the substitution concentration from water in the hydrogel membrane to acetone, cyclohexane, t-butanol, etc. is gradually increased or the number of substitutions is increased. Is preferable.
  • [Drying method 1] is most preferable in order to suppress capillary contraction due to the interfacial tension of the solvent during drying as much as possible.
  • [Drying Method 2] shown in Reference C, Reference D, and [Drying Method 3] shown in Reference E also sacrifice some pore diameter and pore shape.
  • the RF airgel film is carbonized at 600 to 3000 ° C. for 10 minutes to 20 hours in an inert atmosphere or nitrogen atmosphere, and carbon as the RF carbon aerogel of this embodiment is obtained.
  • a porous membrane is obtained.
  • the carbonization treatment can use a carbonization / activation production method such as a fixed bed method, a moving bed method, and a tunnel kiln used for carbonization / activation treatment of solid films and sheets without crushing the carbon precursor.
  • the carbonization temperature can be adjusted according to the target pore diameter.
  • the carbonization temperature is 700 to 1500 ° C., and when it is necessary to further increase the film strength, conductivity and thermal conductivity, the treatment can be performed at 2000 to 3000 ° C.
  • the pore structure can be adjusted by subjecting the obtained carbon porous membrane to an activation treatment as necessary to increase the pore diameter and pore distribution.
  • the activation method it is preferable to use a gas activation method in which firing is performed using an activation gas such as water vapor, hydrogen chloride, carbon monoxide, carbon dioxide, oxygen, or the like.
  • the airgel film shrinks greatly, and if carbonized in a non-tensioned state, the film tends to wrinkle, so it is fixed with a frame or sandwiched between two graphite plates or graphite sheets, It is preferable to carbonize the airgel membrane under tension, or to thermally stabilize the structure in advance at 150 ° C. to 250 ° C. in air or iodine (I 2 ) vapor.
  • FIG. 2 in Kong, Polym., Prep, 30, 221-223 (1989) [hereinafter referred to as Reference Document F] shows a schematic diagram of the formation mechanism of RF airgel, RF airgel and RF as a carbide thereof. Electron micrographs of carbon-based carbon aerogels are described.
  • An aggregate of beaded fine particles forms a carbon porous film as an RF carbon aerogel.
  • An actual carbon porous membrane is considered to have an intermediate structure between a cubic axial pore structure model and a cubic wall porous structure model. It can be seen that the structure is similar to the assembled pore structure model.
  • FIGS. 10 to 13 in Reference Document A contain graphs of the pore distribution of RF-based carbon airgel and graphs of SAXS Debye-Porod analysis.
  • the peak pore radius r (peak) and the pore diameter of the alkali metal bicarbonate are larger than those of the alkali metal carbonate.
  • L is obtained as the dependency of R / C. As R / C increases, the pore diameter L increases, but the pore distribution becomes broad, and the peak of the peak of the pore distribution curve It can be seen that the height also decreases.
  • the pore shape is spherical regardless of the catalyst type because the slope of the Debye-Porod plot is close to ⁇ 4 when the R / C is several hundred (eg, 200) or less. You can see that they are close.
  • Step A2 the coating liquid A was prepared as a thin film by spin coating to obtain a hydrogel film, and then in Step A3, the hydrogel film was gelled (polymerized) at room temperature to 100 ° C. , CO 2 supercritical drying or freeze drying or hot air drying to obtain an airgel membrane, and then the airgel membrane is carbonized at 1000 ° C. as step A4, and finally the carbon porous membrane of this embodiment is obtained.
  • Equation (36) and Equation (37) were obtained.
  • the dependency rate of each factor was 39% for ln (R / Ca), 37% for ln (R / Wa), and 25% for ln (R / F).
  • ⁇ corresponding to the pore radius r is obtained by doubling r and dividing by ⁇ according to the equation (18).
  • a solvated gel film (for example, hydrogel) containing a large amount of a solvent is formed by using a raw material that first undergoes a sol-gel transition by the sol-gel method. It is possible to obtain an airgel film containing a large amount of bubbles by drying and removing only the solvent so as not to be crushed, and finally carbonizing the airgel film to obtain the carbon porous film of this embodiment as a carbon airgel. it can.
  • a carbonaceous raw material is a vinyl halide resin or vinyl halide copolymer resin having a vinyl halide composition of 60 mol% or more (generically referred to as a vinyl halide resin).
  • Highly halogenated vinyl resin having a halogen weight ratio of 60 wt% or more, or a vinylidene halide or vinylidene halide copolymer resin having a vinylidene halide composition of 60 mol% or more (collectively referred to as vinylidene halide resin)
  • vinylidene halide resin a vinylidene halide or vinylidene halide copolymer resin having a vinylidene halide composition of 60 mol% or more
  • vinylidene halide resin A solution in which these resins are dissolved in a good solvent or a latex in which fine particles of a vinylidene halide resin are dispersed in water is prepared. These solutions and latex are collectively referred to as a coating solution B.
  • this coating solution B is applied and formed on a release film or release substrate so that the film thickness after carbonization is 100 nm to 63 ⁇ m.
  • a solvent or water is scattered by drying with hot air and reduced pressure at the following temperature to obtain a thin film resin film of vinylidene halide resin (vinylidene halide resin film).
  • step B3 subsequent to step B2, the vinylidene halide resin film is changed to an aqueous solution of a dehydrohalogenating agent (base) of an alkali metal hydroxide [potassium hydroxide (KOH), sodium hydroxide (NaOH), etc.] and / or Or a solution of a dehydrohalogenating agent (base) in an amine solution [ammonia water (NH 3 water), 1,8-diazabicyclo [5,4,0] -7-undecene (DBU), etc.] and tetrahydrofuran (THF) Using a mixed solution of a good solvent for partially or entirely dissolving vinylidene halide resins such as dimethylformamide (DMF) and a poor solvent for vinylidene halide resins such as water, alcohol and / or ether, and mixing at room temperature to A dehydrohalogenation reaction treatment is performed at a temperature below the boiling point of the solution for 1 second to 2 weeks to obtain a vinyli
  • step B2 and step B3 unlike step A2 and step A3, it takes time to gel the release film or the coating film on the release substrate, or it is peeled off after the coating film is dried with hot air. It is also possible to immerse the coating film directly in the mixed solution without any operation. Contact with the mixed solution causes cross-linking (fixation of structure) of the coating film by dehalogenation, and at the same time, the generated dehydrohalogen gas causes the vinylidene halide resin film from the release film or release substrate. It is because it peels naturally. Therefore, a vinylidene halide resin film can be obtained in an extremely short time compared with Method A.
  • a crosslinked structure called a polyene structure meaning a molecular skeleton structure having —C ⁇ C— or C ⁇ C—
  • Bubbles generated by the hydrogen halide are generated, and a large number of the bubbles remain in the vinylidene halide resin-based carbon precursor film remaining in the film.
  • This carbon precursor film has a number of cross-linked structures, so that the dehydrohalogenation reaction and carbonization (non-destructive carbonization, graphitization) can proceed without melting even in the subsequent step B4.
  • step B4 following step B3, the vinylidene halide resin-based carbon precursor film is heated under tension at 600 to 3000 ° C. for 10 minutes to 20 hours in an inert atmosphere or nitrogen atmosphere as in step A4.
  • carbonization is performed to obtain the vinylidene halide resin-based carbon porous film of the present embodiment.
  • Control of pore diameter and pore distribution by Method B is determined in Step B1 by the composition mol% of high vinyl halide and vinylidene halide in the resin, the molecular weight of the resin, and the resin concentration in the coating liquid B. The higher the value, the smaller the pore size.
  • Step B2 the pore distribution in the film can be sharpened by reducing the film thickness.
  • step B3 the higher the concentration of the base (dehydrohalogenating agent) such as alkali metal hydroxide and amine in the mixed solution, the higher the concentration of the good solvent of the vinylidene halide resin in the mixed solution, the larger the pore size. Becomes larger.
  • step B4 as in step A4, the pore diameter tends to decrease as the carbonization temperature increases.
  • the pore diameter / pore distribution can be increased at 600 ° C. to 1200 ° C.
  • the pore structure can also be adjusted by enlarging the pore diameter and the pore distribution by the activation treatment as in step A4.
  • Method B examples of Reference G and Reference H are described below.
  • Step B1 a vinylidene chloride resin or vinylidene chloride copolymer resin (collectively PVDC resin) having a vinylidene chloride (VDC) composition of 60 mol% or more is dissolved in a carbonaceous raw material using THF as a good solvent for the PVDC resin.
  • PVDC resin vinylidene chloride resin or vinylidene chloride copolymer resin having a vinylidene chloride (VDC) composition of 60 mol% or more
  • the coating liquid B is spin-coated on a glass release substrate so that the film thickness after carbonization becomes 100 to 850 nm, and dried with hot air at 80 ° C. to obtain a thin PVDC resin film.
  • step B3 the PVDC resin film is subjected to dehydrochlorination reaction treatment (deHCl treatment) using a mixed solution of an alkali metal hydroxide KOH aqueous solution, a good solvent THF, and a poor solvent methanol, and a PVDC carbon precursor film.
  • dehydrochlorination reaction treatment deHCl treatment
  • step B4 this PVDC-based carbon precursor film is subjected to tension heating carbonization at 600 to 3000 ° C. in a nitrogen atmosphere to obtain the PVDC-based carbon porous film of the present embodiment.
  • PVDC resin those described in [0011] to [0012] of Reference G can be used.
  • the molar content of the VDC component in the PVDC resin is higher, the polyene structure generated in one molecule is increased by the de-HCl reaction in Step B3, and a cross-linked structure between a plurality of molecules is easily generated. This is preferable because it can be carbonized in a solid state without melting.
  • VDC copolymer a vinylidene chloride copolymer
  • the molar composition ratio of VDC in the VDC copolymer is 0.6 (60 mol%), preferably 0.8 (80 mol%) or more, more preferably 0.9 (90 mol%) or more. preferable.
  • (- CH 2 -CHCl-) n with respect to conventional PVC resin given by the structural formula [Cl content of 57 wt%], the structural formula [(-CH 2 -CHCl-) 4 -CHCl -CHCl -] N , a chlorinated PVC resin having a [Cl content of 61 wt%], a chlorinated rubber having [(—CHCl—C (CH 3 ) Cl—CHCl—CHCl—) n , and a [Cl content of 68 wt%], etc.
  • an aqueous dispersion of PVDC resin called latex or THF, 1,4-dioxane, cyclohexane, cyclopentanone, chlorobenzene, dichlorobenzene shown in [0014] of Reference G is used as the PVDC resin.
  • PVDC resin solution dissolved in a good solvent of PVDC resin such as DMF, methyl ethyl ketone, and ethyl acetate can be used.
  • Preferred good solvents are THF and DMF.
  • the PVDC-based carbon precursor film is subjected to deHCl treatment using the composition and processing conditions of the alkaline processing liquid shown in [0014] to [0015] of Reference G as a mixed solution, and the PVDC-based carbon porous film is It can be carried out under the carbonization conditions shown in [0017] of Reference G. Since the PVDC resin film and PVDC-based carbon precursor film of this embodiment are thin films, the alkali (base) concentration, good solvent concentration, deHCl treatment temperature, and deHCl treatment and carbonization treatment time are described in the same patent document. In comparison, it can be kept low and short.
  • FIG. 3 in Reference G shows a TEM photograph of the PVDC carbon porous membrane.
  • FIG. 2 of the same document is a graph of the pore distribution of the PVDC carbon porous membrane. From FIG. 3 of the same document, a large number of spherical pores surrounded by the pore walls form a PVDC-based carbon porous film. From FIG. 2 of the same document, L ⁇ 13 nm ( ⁇ 1). It can be seen that a large number of .0) pores are formed. Thus, the vinylidene halide-based carbon porous film tends to be a strong carbon porous film with a thicker pore wall thickness than the carbon airgel-based carbon porous film.
  • An actual carbon porous membrane is considered to have an intermediate structure between a cubic axial structure pore structure model and a cubic wall structure pore structure model, but speakingly, the pore structure of the vinylidene halide carbon porous film is It can be seen that the structure is similar to the cubic wall-set pore structure model.
  • Reference H uses a vinylidene fluoride resin (PVDF resin) film instead of PVDC resin, and a mixed solution of organic strong base DBU, PVDF good solvent DMF, and PVDF poor solvent ethanol.
  • PVDF resin vinylidene fluoride resin
  • a method for obtaining a PVDF carbon porous film having a large number of mesopores after carbonization treatment after obtaining a PVDF carbon precursor film by hydrogenation treatment has been introduced. Can be used.
  • Method AB an eclectic method (Method AB) of Method A and Method B is introduced, and this method can also be applied to this embodiment. That is, like the manufacturing process of the carbon porous membrane shown in FIG. 5, a vinyl chloride resin (PVC resin) having a different number average molecular weight M is used as the carbonaceous raw material as the process AB1, and the PVC resin powder is dissolved in DMF. DBU is dropped into the solution at room temperature, and a part of the PVC resin is deHCled to prepare a viscous coating liquid AB composed of three components of PVC, DMF and DBU.
  • PVC resin vinyl chloride resin having a different number average molecular weight M
  • step AB2 the coating liquid AB is applied and formed on the release film or release substrate so that the film thickness after carbonization becomes 100 nm to 63 ⁇ m.
  • the surroundings of the release film and the release substrate are hermetically sealed, the coating film does not flow out of the release film and the release substrate, and the solvent (water) evaporates and the composition of the coating liquid After sealing so as not to change or the region that becomes the membrane pores is not crushed, it is heated at room temperature to 70 ° C. to be sufficiently gelled to obtain a PVC gel membrane.
  • step AB3 after peeling the PVC gel film from the release film or release substrate, the DMF in the gel is directly replaced with liquid CO 2 , and then CO 2 supercritical drying is performed to disperse the solvent and make it porous. A PVC airgel membrane is obtained.
  • step AB4 the PVC-based airgel membrane is heat-stabilized by stepwise heating in air (under O 2 ) at 150 to 250 ° C., or the PVC-based gel membrane is heated with iodine (I 2 ) vapor.
  • heat stabilization at 150 to 250 ° C. heat to 700 ° C. to 3500 ° C. (here 1000 ° C.) in an inert atmosphere or nitrogen atmosphere in the same manner as PVDC carbon porous membrane and PVDF carbon porous membrane.
  • Carbonization can be performed to obtain a porous carbon film made of PVC-based carbon airgel.
  • the PVC airgel film melts and its pore structure collapses. Therefore, unlike the case where chlorinated PVC resin or PVDC resin is used as a carbonaceous raw material, the pore structure by thermal stabilization Immobilization is essential.
  • FIG. 8 in Reference H shows the pore distribution of the PVC-based carbon airgel.
  • FIG. 8 shows the dependency of the molecular weight M on the pore distribution and the dependency of the PVC concentration.
  • the dependence rates of the factors were 66% for [PVC], 27% for M, and 7% for DBU / Cl.
  • ⁇ corresponding to the pore radius r is obtained by doubling r and dividing by ⁇ according to Equation 2.
  • the carbon porous film of this embodiment can be obtained as a halogenated vinyl resin-based or halogenated vinylidene resin-based carbon porous film.
  • FIG. 6 is a perspective view showing a pellicle.
  • FIG. 7 is a diagram showing a cross-sectional configuration along the line VII-VII in FIG.
  • the pellicle 10 of the present embodiment is obtained by bonding the above-described carbon porous film to the frame 3 using the film adhesive 2 as the pellicle film 1.
  • a bonding mechanism 4 with a mask adhesive (including its protective film) or a frame is provided on the side of the pellicle that is bonded to the mask.
  • the frame material is preferably an Al—Zn-based aluminum alloy frame (7000-based aluminum alloy frame) in which Zn and Mg are added to increase the strength among aluminum alloys. More preferably, in order to suppress stray light when the EUV light is irradiated onto the frame, elements Mg and Si having a refractive index of EUV light close to a vacuum refractive index of 1.0 and a large extinction coefficient k are added to provide strength and corrosion resistance.
  • the mask adhesive 4 for example, an adhesive containing a reaction product of a (meth) acrylic acid alkyl ester and a polyfunctional epoxy compound used in an ArF pellicle introduced in JP 2011-107488 A is used. Can be used. When EUV light is applied to the adhesive, decomposition gas may be generated from the components of the adhesive. Therefore, when the frame is bonded to the mask, the frame adhesive should not protrude from the edge of the frame width. It can be applied narrower than the width of 3. Moreover, as an arrangement
  • the mask adhesive 4 is applied in the groove 6 slightly thicker than the depth of the groove 6.
  • grooves 7 and 8 may be further provided on both sides of the groove 6 where the mask adhesive 4 is disposed so that the mask adhesive does not protrude from the width of the frame.
  • the EUV mask usually peels off the pellicle and is often used again. In this case, the adhesive residue of the mask adhesive on the EUV mask sometimes becomes a problem. Therefore, as a bonding mechanism between the pellicle 10 and the EUV mask, instead of the mask adhesive, as shown in FIG. 9, the conductive coil 12 is attached to the wire core 11 of a ferromagnetic material such as iron Fe, cobalt Co, nickel Ni or the like. Electromagnets 13 wound with metal nanowires, carbon nanowires, etc. are embedded in the grooves 6 of the frame 3 or joined with an adhesive or the like, and on the other hand, a ferromagnetic surface is provided on the EUV mask side as well. It is more preferable to join to. Instead of installing the electromagnet 13 on the frame 3, an electromagnet can be installed on the EUV mask side, and a ferromagnetic wire or the like can be provided in the groove of the frame.
  • a ferromagnetic wire or the like can be provided in the groove of the frame
  • a mask for EUV made of a multilayer film in which Si and molybdenum (Mo) are alternately deposited on 40 layers of zero expansion glass (LTE glass) alternately a mask that adheres to a frame is used.
  • a frame or seal made of ferromagnetism such as permalloy thin film or amorphous rare earth iron alloy film in advance is affixed to these areas, or these ferromagnetic thin films are produced by vacuum deposition, sputter deposition, or electrodeposition. You just have to.
  • an inorganic adhesive that has adhesive force and generates little decomposition gas even when irradiated with EUV light and does not affect the exposure.
  • an epoxy resin adhesive mixed with an inorganic substance for example, A-3 / C-3 (epoxy resin adhesive using carbon black as a filler) manufactured by Fujikura Kasei Co., Ltd.
  • a phenolic adhesive mixed with an inorganic substance for example, FC-403R / XC-223 manufactured by Fujikura Kasei Co., Ltd. (phenolic resin adhesive using graphite as a filler) or inorganic reactive adhesives such as silicate, phosphate, and colloidal silica can be used.
  • the mask adhesive 4 when the mask adhesive 4 is used after the frame 3 previously coated with the film adhesive 2 and the pellicle film 1 of the present embodiment are bonded, the mask adhesive on the bonding surface side of the frame 3 with the EUV mask is used.
  • the pellicle 10 of this embodiment can be obtained by applying 4 and then attaching a protective film.
  • the present invention can be suitably used in the field of EUV lithography as a pellicle film and a pellicle for protecting a lithography mask from contamination.

Abstract

Provided are a pellicle film and a pellicle which exhibit excellent transmittance with respect to extreme ultraviolet (EUV) light, and sufficient physical strength and durability in practical use, and with which film fragments can be easily removed, and excellent productivity can be achieved. A pellicle film (1) is configured using a carbon porous-body film, and has a film thickness (D) in the range of 100 nm - 63 µm.

Description

ペリクル膜及びペリクルPellicle membrane and pellicle
　本発明は、極端紫外光を用いたリソグラフィ用のペリクル膜及び該ペリクル膜を備えたペリクルに関する。 The present invention relates to a pellicle film for lithography using extreme ultraviolet light and a pellicle provided with the pellicle film.
　半導体集積回路は、１９６０年代に生産が開始されてから、集積度の向上が図られ、１９７０代初頭から最近に至るまで、３年に約４倍の高集積化が実現されるという目覚ましい高集積化が続いている。この半導体集積回路の高集積化に貢献してきた技術が、光リソグラフィと呼ばれる露光技術である。この露光技術では、半導体集積回路の配線の最小線幅が解像度により決まり、得られる解像度は、レイリーの式に従い、露光光学系の開口度、露光装置のＫ１ファクターと呼ばれる装置定数と露光波長λ（以下、単にλとも記載）に依存している。この結果、４５ｎｍ以下の解像度を得るためには、露光波長をＥＵＶ領域と呼ばれるλ＝６～１４ｎｍの極端紫外光（以下、ＥＵＶ（Ｅｘｔｒｅｍｅ　Ｕｌｔｒａ　Ｖｉｏｌｅｔ）光とも記載）を用いたＥＵＶリソグラフィが最も有力なものと考えられている。 Semiconductor integrated circuits have been improved since the start of production in the 1960s, and the degree of integration has been improved. From the beginning of the 1970s to the present, the integration of about 4 times has been achieved in three years. The process continues. A technique that has contributed to the high integration of this semiconductor integrated circuit is an exposure technique called optical lithography. In this exposure technique, the minimum line width of the wiring of the semiconductor integrated circuit is determined by the resolution, and the obtained resolution is in accordance with the Rayleigh equation, the aperture of the exposure optical system, the apparatus constant called the K1 factor of the exposure apparatus, and the exposure wavelength λ ( Hereinafter, it is simply described as λ). As a result, in order to obtain a resolution of 45 nm or less, EUV lithography using λ = 6 to 14 nm of extreme ultraviolet light (hereinafter also referred to as EUV (Extreme Ultra Violet) light) called the EUV region is the most promising. It is thought that.
　ＥＵＶリソグラフィ開発における現時点での課題としては、ＥＵＶ用光源の出力、ＥＵＶ用レジスト、ＥＵＶ用マスクの欠陥やコンタミネーション粒子等が挙げられている。その中でも、ＥＵＶ用光源の出力、具体的にはＥＵＶ光源の出力を十分に大きくできないことは、全ての課題に大きく影響している。例えば、ＥＵＶ用マスクのコンタミネーション粒子に関する課題では、ＥＵＶ光がほとんど全ての物質に大きく吸収されるため、従来の露光波長、４３６ｎｍ（ｇ線）、３６５ｎｍ（ｉ線）、２４８ｎｍ（ＫｒＦ）、１９３ｎｍ（ＡｒＦ）等での透過縮小投影露光技術とは異なり、ＥＵＶリソグラフィでは、反射縮小投影露光技術を用い、ＥＵＶ用マスクを含む全ての露光装置のコンポーネントが真空中に配置される。 Current issues in EUV lithography development include output of EUV light source, EUV resist, EUV mask defects, contamination particles, and the like. Among them, the fact that the output of the EUV light source, specifically, the output of the EUV light source cannot be sufficiently increased greatly affects all the problems. For example, in the problem related to the contamination particles of the EUV mask, since EUV light is largely absorbed by almost all substances, the conventional exposure wavelength, 436 nm (g-line), 365 nm (i-line), 248 nm (KrF), 193 nm Unlike the transmission reduction projection exposure technique using (ArF) or the like, the EUV lithography uses the reflection reduction projection exposure technique, and all the components of the exposure apparatus including the EUV mask are arranged in a vacuum.
　しかしながら、最近のＥＵＶリソグラフィの実証テストから、コンポーネントが真空中に配置されていても、コンタミネーション粒子は露光装置中に多量に発生しており、ＥＵＶ用マスクの洗浄が頻繁に必要となる可能性が予想されている。そのため、ＥＵＶ用光源の出力（中間集光点値）が数百Ｗ以上得られるようになれば、従来通りペリクルが必要となる。 However, according to recent demonstration tests of EUV lithography, even if the components are placed in a vacuum, contamination particles may be generated in large amounts in the exposure apparatus, and it may be necessary to frequently clean the EUV mask. Is expected. Therefore, if the output (intermediate condensing point value) of the EUV light source can be obtained by several hundred W or more, a pellicle is required as usual.
　ＥＵＶ用ペリクルに用いられるペリクル膜としては、これまでに以下に示す４種類の膜構造を有するものが提案されている。第１の膜構造は、ＥＵＶ光に対して消光係数ｋ（以下、単にｋとも記載）が低い元素、例えば炭素Ｃからなるカーボンナノチューブ（Ｃａｒｂｏｎ　Ｎａｎｏ　Ｔｕｂｅ：ＣＮＴ）等をＥＵＶ用マスク表面に柱状（数十ｎｍの間隔、高さ数μｍ）に成長させている（例えば、特許文献１参照）。 As pellicle films used for EUV pellicles, those having the following four types of film structures have been proposed. The first film structure is made of an element having a low extinction coefficient k (hereinafter also simply referred to as k) with respect to EUV light, such as carbon nanotubes (Carbon Nano Tube: CNT), etc. It is grown at intervals of several tens of nm and a height of several μm (see, for example, Patent Document 1).
　第２の膜構造は、λ＝１３．５ｎｍのＥＵＶ光に対してｋが低い元素として珪素Ｓｉを用いて、膜厚２０～１５０ｎｍの極めて薄い平膜を作り、これをＥＵＶ用ペリクル膜としている（例えば、特許文献２参照）。 In the second film structure, an extremely thin flat film having a film thickness of 20 to 150 nm is formed using silicon Si as an element having a low k with respect to EUV light with λ = 13.5 nm, and this is used as a pellicle film for EUV. (For example, refer to Patent Document 2).
　第３の膜構造は、ＥＵＶ光に対してｋが低い元素（珪素（Ｓｉ）、ルテニウム（Ｒｕ）、イリジウム（Ｉｒ）、金（Ａｕ）、レニウム（Ｒｈ）、炭素（Ｃ）等）、又は、化合物（窒化アルミニウム（ＡｌＮ）、窒化珪素（ＳｉＮ）、炭化珪素（ＳｉＣ）等）を用いて、膜厚３０～３００ｎｍの単層又は多層の平膜と、矩形状、ハニカム状等の開口部を有し、線径が数十μｍ、線と線との周期が数百μｍ～数ｍｍの、いわゆるグリッド、メッシュと呼ばれる膜（以下、支持膜とも記載）とを接合した複合膜である（例えば、特許文献３～５、非特許文献２参照）。 The third film structure is an element having low k with respect to EUV light (silicon (Si), ruthenium (Ru), iridium (Ir), gold (Au), rhenium (Rh), carbon (C), etc.), or Using a compound (aluminum nitride (AlN), silicon nitride (SiN), silicon carbide (SiC), etc.) and a single-layer or multi-layer flat film having a film thickness of 30 to 300 nm, and openings such as rectangular and honeycomb-shaped A composite membrane in which a so-called grid or mesh membrane (hereinafter also referred to as a support membrane) having a wire diameter of several tens of μm and a cycle of lines of several hundred μm to several mm is joined (hereinafter also referred to as a support membrane) ( For example, see Patent Documents 3 to 5 and Non-Patent Document 2).
　第４の膜構造は、ＥＵＶ光に対してｋが低い、元素（Ｓｉ、Ｒｕ、Ｃ等）から作製したエアロゲル膜をＥＵＶ用ペリクル膜としたものである。エアロゲル膜とは、空気を９０．０～９９．８％も含む、見かけ密度が数１０－３～数１０－１ｇ／ｃｍ３のミクロ孔、メソ孔、マクロ孔を多数有するスポンジ状の多孔膜である。入射されるＥＵＶ光の波長よりエアロゲル膜中の細孔径を十分小さくし、レイリー散乱による透過率の低下を最小化したエアロゲル膜を用いることで、膜厚が約１．０～１０．０μｍという支持膜なしでも十分な膜強度を有し、且つＥＵＶ光に対して高透過率を有する膜が得られるとされている（例えば、特許文献６、７参照）。 In the fourth film structure, an airgel film made of an element (Si, Ru, C, etc.) having a low k for EUV light is used as a pellicle film for EUV. The airgel membrane is a sponge-like porous material containing a large number of micropores, mesopores, and macropores having an apparent density of several tens -3 to several tens -1 g / cm 3 , including air of 90.0 to 99.8%. It is a membrane. By using an airgel film in which the pore diameter in the airgel film is sufficiently smaller than the wavelength of the incident EUV light and the decrease in transmittance due to Rayleigh scattering is minimized, the film thickness is about 1.0 to 10.0 μm. It is said that a film having sufficient film strength and high transmittance for EUV light can be obtained without a film (see, for example, Patent Documents 6 and 7).
　この膜構造は、（１）ＥＵＶ領域の物質の吸収が、物質の元素の種類と物質の密度に大きく依存していること、（２）レイリー散乱を許す程度の発泡体構造（多孔膜）とすることで、膜厚を確保し、膜強度を高められること、に着目したものである。特に、特許文献６では、フッ化水素ＨＦを主成分とする溶液を用いて電気化学的にＳｉを溶解させて作製したシリコンエアロゲル（Ｓｉエアロゲル）により、ＥＵＶ光の透過率が高いＥＵＶ用ペリクル膜が得られ、また貴金属又はＲｕ等の遷移金属イオンを含むヒドロゲルにγ線で照射し、金属ナノ粒子を析出して作製した金属発泡エアロゲルにより、高い耐酸化性を有するＥＵＶ用ペリクル膜が得られるとされている。 This film structure has the following features: (1) Absorption of substances in the EUV region is highly dependent on the type of element and density of the substance, and (2) a foam structure (porous film) that allows Rayleigh scattering. In this way, attention is paid to securing the film thickness and increasing the film strength. In particular, in Patent Document 6, a pellicle film for EUV light having a high EUV light transmittance is obtained by silicon aerogel (Si airgel) produced by electrochemically dissolving Si using a solution containing hydrogen fluoride HF as a main component. A pellicle film for EUV having high oxidation resistance can be obtained by using a metal foam aerogel prepared by irradiating a hydrogel containing a transition metal ion such as a noble metal or Ru with γ rays to deposit metal nanoparticles. It is said that.
　また、特許文献７では、この膜構造をＣＮＴにより実現しようとする試みが示されている。この構造は、ＣＮＴ自体を何らかの方法を用いて、厚みが１．０～５．０ｎｍの膜を作成し、ＥＵＶ用ペリクル膜として用いる。ＣＮＴ膜の見かけ密度を１．５×１０－３～０．５ｇ／ｃｍ３とすることでエアロゲルに似た膜構造体を得ることができるとしている。 Patent Document 7 shows an attempt to realize this film structure with CNTs. In this structure, the CNT itself is used as a pellicle film for EUV by forming a film having a thickness of 1.0 to 5.0 nm by some method. By setting the apparent density of the CNT film to 1.5 × 10 −3 to 0.5 g / cm 3 , a film structure similar to an airgel can be obtained.
米国特許第７７６３３９４号明細書US Patent No. 776394 特開２００９－２７１２６２号公報JP 2009-271262 A 特開２００５－４３８９５号公報Japanese Patent Laying-Open No. 2005-43895 米国特許第７１５３６１５号明細書US Pat. No. 7,153,615 特開２０１０－２５６４３４号公報JP 2010-256434 A 特開２０１０－５０９７７４号公報JP 2010-509774 A 米国特許第７７６７９８５号明細書US Pat. No. 7,767,985
　しかしながら、上記の第１の膜構造は、ｋが低い元素としてＣを使っているが、ＥＵＶ用マスク表面に防塵保護膜が直接接触する構造であり、マスク面とペリクル膜の一部分との焦点が重なるため、ペリクルとしての性能を発揮できない可能性がある。また、ＣＮＴの構造制御が極めて難しく、製造コストが高くなるおそれがある。したがって、第１の膜構造は現実的ではない。 However, although the first film structure uses C as an element having a low k, the dust-proof protective film is in direct contact with the EUV mask surface, and the focus of the mask surface and a part of the pellicle film is Since they overlap, there is a possibility that the performance as a pellicle cannot be exhibited. In addition, the structure control of CNTs is extremely difficult, and the production cost may increase. Therefore, the first film structure is not realistic.
　第２の膜構造は、ｋの低いＳｉを用いたとしても、ペリクル膜をＥＵＶ光が２回通過した際の透過率を５０％以上確保しようとすると、膜の厚みを２００ｎｍ以下とする必要がある。そのため、高い透過率を得るためには極めて膜厚が薄い平膜が必要となり、膜自体の強度を確保することが難しい。更に、ペリクル膜としてＳｉを使用した場合、衝撃等によりペリクル膜が破損すると、その破片がＥＵＶ用マスク表面上に付着することがある。この場合、ペリクル膜として機能しないだけでなく、除去することが困難なコンタミネーション粒子となってしまう問題が生じ得る。 Even if Si with low k is used for the second film structure, if the transmittance when EUV light passes through the pellicle film twice is to be secured 50% or more, the film thickness needs to be 200 nm or less. is there. Therefore, in order to obtain a high transmittance, a flat film having a very thin film thickness is required, and it is difficult to ensure the strength of the film itself. Further, when Si is used as the pellicle film, if the pellicle film is damaged due to impact or the like, the fragments may adhere to the EUV mask surface. In this case, not only does it not function as a pellicle film, but there may arise a problem that it becomes contamination particles that are difficult to remove.
　第３の膜構造は、膜強度を確保することについては有効な構成であり、膜厚を薄くすることを可能としている。しかしながら、支持膜自体がＥＵＶ用マスクへの入射光及びＥＵＶ用マスクからの反射光に対し、障害物や制限視野として働き、平膜単独の透過率に比べ、透過率を３０～６０％程度下げることとなる。また、ペリクル膜の素材として、炭素Ｃ以外のものを用いた場合には、破損時におけるコンタミネーション粒子の問題が生じ得る。 The third film structure is an effective configuration for securing the film strength, and enables the film thickness to be reduced. However, the support film itself acts as an obstacle and a limited visual field for the incident light to the EUV mask and the reflected light from the EUV mask, and the transmittance is reduced by about 30 to 60% compared to the transmittance of the flat film alone. It will be. Further, when a material other than carbon C is used as the material of the pellicle film, there may be a problem of contamination particles at the time of breakage.
　第４の膜構造は、ＥＵＶ光に対し高い透過性を確保するだけでなく、第２の膜構造及び第３の膜構造に比べ、膜厚に関する制約を大幅に改善するという点で優位性がある。しかしながら、特許文献６に示されたＥＵＶペリクル膜には、次の様な問題がある。すなわち、第３の膜構造と同様に、Ｃ以外の元素からなるエアロゲル膜をＥＵＶ用ペリクル膜とした場合、衝撃等の何らかの原因でＥＵＶ用ペリクル膜が破損すると、除去することが困難なコンタミネーション粒子となってしまう問題が生じ得る。 The fourth film structure has an advantage in that not only the high transmittance to EUV light is ensured, but also the restrictions on the film thickness are greatly improved as compared with the second film structure and the third film structure. is there. However, the EUV pellicle film disclosed in Patent Document 6 has the following problems. That is, as in the third film structure, when an airgel film made of an element other than C is used as an EUV pellicle film, it is difficult to remove contamination if the EUV pellicle film is damaged for some reason such as impact. The problem of becoming particles can arise.
　また、特許文献７に示されたＣＮＴ膜をエアロゲル膜として用いた場合にも以下の様な問題がある。直径１～２ｎｍ、繊維長が数１０μｍのＣＮＴを用いて、極めて薄い膜厚１．０～５．０ｎｍのエアロゲル膜を形成したとしても、十分な機械的な膜強度は得られない。一方で、十分な機械的な膜強度を得ようと、見かけ密度を通常炭素の密度１．５ｇ／ｃｍ３程度まで高めた場合、本来のエアロゲル膜で得られるような高い透過率を得ることはできない。 Moreover, when the CNT film | membrane shown by patent document 7 is used as an airgel film, there exist the following problems. Even if an extremely thin airgel film having a thickness of 1.0 to 5.0 nm is formed using CNTs having a diameter of 1 to 2 nm and a fiber length of several tens of μm, sufficient mechanical film strength cannot be obtained. On the other hand, in order to obtain sufficient mechanical film strength, when the apparent density is increased to a normal carbon density of about 1.5 g / cm 3 , it is possible to obtain a high transmittance as obtained with an original airgel film. Can not.
　更に、一般的に、ＣＮＴはその製造過程で、消光係数の高い鉄Ｆｅ、コバルトＣｏ、ニッケルＮｉ等の金属触媒を多量に用いるため、必然的に多量の不純物を含み、そのまま用いると消光係数の大きい炭素膜となってしまい、高い透過率を得ることはできない。また、消光係数の低い炭素膜のみとするために上記不純物を除去する場合、その生産性が低下し、製造コストが極めて高くなるという問題もある。 Furthermore, in general, CNT uses a large amount of a metal catalyst such as iron Fe, cobalt Co, nickel Ni or the like having a high extinction coefficient in the production process. Therefore, the CNT inevitably contains a large amount of impurities. It becomes a large carbon film, and high transmittance cannot be obtained. Further, when the impurities are removed in order to use only a carbon film having a low extinction coefficient, there is a problem that the productivity is lowered and the manufacturing cost is extremely increased.
　本発明は、ＥＵＶ光に対する高い透過性を有し、実用上十分な物理強度と耐久性を有すると共に、膜破片を容易に除去でき、且つ生産性に優れたペリクル膜及びペリクルを提供することを目的とする。 The present invention provides a pellicle film and a pellicle that have high transparency to EUV light, have practically sufficient physical strength and durability, can easily remove film fragments, and are excellent in productivity. Objective.
　本発明者は、上記課題を解決するため、鋭意検討を行った結果、ペリクル膜の素材を汎用的な炭素とすることで、万が一、膜の一部が破損し、ＥＵＶ用マスク表面に付着した場合でも、容易に除去することが可能であると共に、ペリクルに用い得る細孔径・細孔径分布、及び見かけ密度を有する多孔膜を生産性良く安価に提供することが可能であり、上記課題を解決できることを見出した。 As a result of intensive studies to solve the above-mentioned problems, the present inventor made a general-purpose carbon pellicle film material so that part of the film was damaged and adhered to the EUV mask surface. Even in this case, it is possible to easily remove the porous film having a pore diameter / pore diameter distribution and an apparent density that can be used for a pellicle at a low cost with high productivity. I found out that I can do it.
　すなわち、本発明の一側面に係るペリクル膜は、炭素多孔体膜で構成されており、膜厚Ｄが１００ｎｍ～６３μｍである。 That is, the pellicle film according to one aspect of the present invention is composed of a carbon porous film, and the film thickness D is 100 nm to 63 μm.
　一実施形態においては、１３．５ｎｍの波長の極端紫外光が１回通過する際の透過率Ｔが８４％以上であり、且つ、極端紫外光が１回通過する際の炭素多孔体膜の細孔による散乱量Δが１０％以下であってもよい。 In one embodiment, the transmittance T when the extreme ultraviolet light having the wavelength of 13.5 nm passes once is 84% or more, and the fineness of the carbon porous membrane when the extreme ultraviolet light passes once The scattering amount Δ due to the holes may be 10% or less.
　一実施形態においては、炭素多孔体膜において、質量を体積で割って得られる見かけ密度が１．０×１０－３～２．１ｇ／ｃｍ３であってもよい。 In one embodiment, the apparent density obtained by dividing the mass by the volume in the porous carbon membrane may be 1.0 × 10 −3 to 2.1 g / cm 3 .
　一実施形態においては、極端紫外光の波長λを１３．５ｎｍ、黒鉛の密度Ｗを２．２５ｇ／ｃｍ３、炭素多孔体膜の見かけ密度（ｇ／ｃｍ３）をρ、膜厚をＤ（ｎｍ）としたとき、炭素多孔体膜が、以下の各式（１）～（５）を満たす構造パラメータを有していてもよい。
α≦３０（α：細孔サイズパラメータ）　…（１）
０．３３５≦Ｎｄ≦１３（Ｎ：膜厚方向への細孔数（個）、ｄ：細孔の壁厚（ｎｍ））　…（２）
αλ／ｄ≦８１（λ：露光波長（ｎｍ））　…（３）
ただし、上記のＮ、ｄは、
Ｎ＝－１＋｛（Ｗ－ρ）１／３／Ｗ１／３｝＋｛Ｄ（Ｗ－ρ）１／３／αλＷ１／３｝　…（４）
ｄ＝－αλ＋｛αλＷ１／３／（Ｗ－ρ）１／３｝　…（５） In one embodiment, the wavelength λ of extreme ultraviolet light is 13.5 nm, the density W of graphite is 2.25 g / cm 3 , the apparent density (g / cm 3 ) of the porous carbon film is ρ, and the film thickness is D ( nm), the carbon porous membrane may have structural parameters satisfying the following formulas (1) to (5).
α ≦ 30 (α: pore size parameter) (1)
0.335 ≦ Nd ≦ 13 (N: number of pores in the film thickness direction (pieces), d: wall thickness of the pores (nm)) (2)
αλ / d ≦ 81 (λ: exposure wavelength (nm)) (3)
However, the above N and d are
N = −1 + {(W−ρ) 1/3 / W 1/3 } + {D (W−ρ) 1/3 / αλW 1/3 } (4)
d = −αλ + {αλW 1/3 / (W−ρ) 1/3 } (5)
　一実施形態においては、極端紫外光の波長λを１３．５ｎｍ、黒鉛の密度Ｗを２．２５ｇ／ｃｍ３、炭素多孔体膜の見かけ密度（ｇ／ｃｍ３）をρ、膜厚（ｎｍ）をＤとしたとき、炭素多孔体膜が、以下の各式（６）～（９）を満たす構造パラメータを有していてもよい。
α≦３０（α：細孔サイズパラメータ）　…（６）
αλ／ｄ≦８１（λ：露光波長（ｎｍ））　…（７）
０．０８ｇ／ｃｍ３≦ρ≦０．７ｇ／ｃｍ３　…（８）
Ｄ：１００≦Ｄ≦８５０　…（９） In one embodiment, the wavelength λ of extreme ultraviolet light is 13.5 nm, the density W of graphite is 2.25 g / cm 3 , the apparent density (g / cm 3 ) of the porous carbon film is ρ, and the film thickness (nm) Is D, the carbon porous membrane may have structural parameters satisfying the following formulas (6) to (9).
α ≦ 30 (α: pore size parameter) (6)
αλ / d ≦ 81 (λ: exposure wavelength (nm)) (7)
0.08 g / cm 3 ≦ ρ ≦ 0.7 g / cm 3 (8)
D: 100 ≦ D ≦ 850 (9)
　本発明の他側面に係るペリクルは、上記のペリクル膜と、ペリクル膜が貼付されるフレームと、を備える。 A pellicle according to another aspect of the present invention includes the pellicle film described above and a frame to which the pellicle film is attached.
　一実施形態においては、フレームには、ペリクル膜が貼付される面とは反対の面に、リソグラフィマスクと接合するためのマスク粘着剤が配設される溝が設けられていてもよい。 In one embodiment, the frame may be provided with a groove in which a mask adhesive for bonding to the lithography mask is disposed on the surface opposite to the surface to which the pellicle film is attached.
　一実施形態においては、フレームには、ペリクル膜が支持される面とは反対の面に、リソグラフィマスクと接合するための電磁石が設けられていてもよい。 In one embodiment, the frame may be provided with an electromagnet for bonding to the lithography mask on the surface opposite to the surface on which the pellicle film is supported.
　本発明によれば、ＥＵＶ光に対する高い透過性を有し、実用上十分な物理強度と耐久性を有すると共に、膜破片を容易に除去でき、且つ生産性に優れたものとすることができる。 According to the present invention, it has high transmittance to EUV light, has practically sufficient physical strength and durability, can easily remove film fragments, and has excellent productivity.
（ａ）は、消光係数と透過率及び反射率との関係を示すグラフであり、（ｂ）は、屈折率と透過率及び反射率との関係を示すグラフである。(A) is a graph which shows the relationship between an extinction coefficient, a transmittance | permeability, and a reflectance, (b) is a graph which shows the relationship between a refractive index, a transmittance | permeability, and a reflectance. 波長と屈折率及び消光係数との関係を示すグラフである。It is a graph which shows the relationship between a wavelength, a refractive index, and an extinction coefficient. 見かけ密度と屈折率及び消光係数との関係を示すグラフである。It is a graph which shows the relationship between an apparent density, a refractive index, and an extinction coefficient. 炭素多孔体膜の構造モデルを示す模式図である。It is a schematic diagram which shows the structural model of a carbon porous body film. 炭素多孔体膜の製造工程を示す図である。It is a figure which shows the manufacturing process of a carbon porous body film. 一実施形態に係るペリクルを示す斜視図である。It is a perspective view which shows the pellicle which concerns on one Embodiment. 図６におけるＶＩＩ－ＶＩＩ線での断面構成を示す図である。It is a figure which shows the cross-sectional structure in the VII-VII line in FIG. フレームの断面構成を示す図である。It is a figure which shows the cross-sectional structure of a flame | frame. フレームの断面構成を示す図である。It is a figure which shows the cross-sectional structure of a flame | frame.
　以下、添付図面を参照して、本発明の好適な実施形態について詳細に説明する。なお、図面の説明において同一又は相当要素には同一符号を付し、重複する説明は省略する。 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.
　本実施形態について、以下、「１．本実施形態で使用する用語の定義又は説明」を説明した後、「２．本実施形態のペリクル膜」、「３．本実施形態のペリクル」の順に具体的に説明する。 Hereinafter, after describing “1. Definition or explanation of terms used in this embodiment”, this embodiment will be described in the order of “2. Pellicle film of this embodiment” and “3. Pellicle of this embodiment”. I will explain it.
１．本実施形態で使用する用語の定義又は説明
［本実施形態の基準値］
　本実施形態の基準値とは、本実施形態の課題を達成する上で好ましいペリクル膜の、透過率、散乱量及び膜厚の３つの物性値の値を示す。 1. Definition or explanation of terms used in this embodiment [reference value of this embodiment]
The reference value of the present embodiment indicates three physical property values of transmittance, scattering amount, and film thickness of a pellicle film that is preferable for achieving the object of the present embodiment.
　ペリクル膜の透過率Ｔ（以下、Ｔとも記載、単位は％）の値は、ＥＵＶリソグラフィで用いられる１枚の反射鏡の反射率７０％以上であることが好ましく、Ｔの基準値とした。露光時、一般的には、ＥＵＶ（Ｅｘｔｒｅｍｅ　Ｕｌｔｒａ　Ｖｉｏｌｅｔ：極端紫外）光は入射角θ＝６°でＥＵＶ用マスク面に入射・反射され、ＥＵＶ用マスク面を覆ったペリクル膜を往復で２回通過することから、ペリクル膜を１回通過する場合の好ましいＴは８４％以上となる（２回通過すると、８４％×８４％＝７０％となるため）。同様に２回通過時、８０％以上、９０％以上のＴを得るには、１回通過時での必要なＴは、それぞれ８９％以上、９５％以上となる。このＴに関する基準値を以下、「透過率基準値」と称し、８４％、８９％、９５％の基準値をそれぞれ第１透過率基準（Ｔ１）、第２透過率基準（Ｔ２）、第３透過率基準（Ｔ３）と称する。 The transmittance T of the pellicle film (hereinafter also referred to as T, the unit is%) is preferably 70% or more of the reflectance of a single reflector used in EUV lithography, and is used as a reference value for T. At the time of exposure, EUV (Extreme Ultra Violet) light is generally incident and reflected on the EUV mask surface at an incident angle θ = 6 °, and the pellicle film covering the EUV mask surface is reciprocated twice. Therefore, the preferable T when passing through the pellicle film once is 84% or more (since passing twice, it becomes 84% × 84% = 70%). Similarly, in order to obtain T of 80% or more and 90% or more at the time of two passes, the necessary T at the time of one pass is 89% or more and 95% or more, respectively. The reference value for T is hereinafter referred to as “transmittance reference value”, and the reference values of 84%, 89%, and 95% are set as the first transmittance reference (T1), the second transmittance reference (T2), and the third reference value, respectively. This is referred to as the transmittance standard (T3).
　ペリクル膜が多孔膜であるために生じる散乱量（以下、Δとも記載、単位は％）は、その値が大きいと、Ｔが小さくなるだけでなく、露光時にＥＵＶ用マスク表面で回路像のボケを発生する。そのため、散乱量は、できるだけ値が小さいことが望まれるが、明確な基準値は存在しない。本実施形態では、ペリクル膜を１回通過する場合の、好ましい範囲と考えられる散乱量の上限を「散乱量基準値」として、１０％、５％、１％の基準値をそれぞれ、第１散乱量基準（Δ１）、第２散乱量基準（Δ２）、第３散乱量基準（Δ３）と称する。なお、散乱量に関しては、ＥＵＶ用マスク面を覆ったペリクル膜を往復で２回通過する場合の散乱量は、概ね１回通過時の散乱量の２倍となると考えられる。 When the pellicle film is a porous film, the amount of scattering (hereinafter also referred to as Δ, the unit is%) is not only small when T is small, but also the blur of the circuit image on the EUV mask surface during exposure. Is generated. Therefore, it is desired that the scattering amount is as small as possible, but there is no clear reference value. In the present embodiment, the upper limit of the amount of scattering considered to be a preferable range when passing through the pellicle film once is defined as the “scattering amount reference value”, and the reference values of 10%, 5%, and 1% are respectively used as the first scattering. These are referred to as an amount reference (Δ1), a second scattering amount reference (Δ2), and a third scattering amount reference (Δ3). Regarding the amount of scattering, it is considered that the amount of scattering when the pellicle film covering the EUV mask surface is passed twice in a reciprocating manner is approximately twice the amount of scattering when passing once.
　ペリクル膜の膜厚（以下、Ｄとも記載、単位はｎｍ）は、膜強度（膜の曲げ剛性）、膜の取り扱いやすさに大きな影響を与える。従来のＳｉ単体の平膜を用いたペリクル膜では、ペリクル膜を往復で２回通過する時に７０％以上のＴを得るため、Ｄを５０～１００ｎｍにせざるを得なかった。本実施形態のように炭素多孔膜を用いることで、透過率を維持したままＤを厚くすることができる。そこで、Ｄ＝１００ｎｍ以上を本実施形態の必要最低限の膜厚とする。膜厚Ｄは、好ましくは３００ｎｍ以上、より好ましくは５００ｎｍ以上である。このＤに関する基準値を以下、「膜厚基準値」と称し、１００ｎｍ、３００ｎｍ、５００ｎｍの基準をそれぞれ第１膜厚基準（Ｄ１）、第２膜厚基準（Ｄ２）、第３膜厚基準（Ｄ３）と称する。 The film thickness of the pellicle film (hereinafter also referred to as D, the unit is nm) has a great influence on the film strength (bending rigidity of the film) and the ease of handling of the film. In a pellicle film using a conventional flat film of Si alone, D is unavoidably set to 50 to 100 nm in order to obtain a T of 70% or more when passing through the pellicle film twice. By using a carbon porous membrane as in this embodiment, D can be made thick while maintaining the transmittance. Therefore, D = 100 nm or more is set as the minimum necessary film thickness of the present embodiment. The film thickness D is preferably 300 nm or more, more preferably 500 nm or more. The reference value for D is hereinafter referred to as “film thickness reference value”, and the standards of 100 nm, 300 nm, and 500 nm are respectively referred to as the first film thickness standard (D1), the second film thickness standard (D2), and the third film thickness standard ( D3).
［本実施形態のペリクル膜の構造モデル］
　本実施形態のペリクル膜は、炭素多孔膜で構成されており、ペリクル膜の膜厚Ｄが１００ｎｍ～６３μｍである。また、本実施形態のペリクル膜は、後述する特定の構造を有していることが好ましい。以下、ペリクル膜の構造を規定するために用いた、前提、炭素多孔膜の構造モデル、及び、各構造パラメータについて説明する。 [Structural model of pellicle film of this embodiment]
The pellicle film of this embodiment is composed of a carbon porous film, and the thickness D of the pellicle film is 100 nm to 63 μm. The pellicle film of this embodiment preferably has a specific structure described later. Hereinafter, the premise, the structural model of the carbon porous film, and each structural parameter used for defining the structure of the pellicle film will be described.
（前提１）
　現実の炭素多孔膜は、細孔が単分散（細孔の細孔径、壁厚又は柱太さ、形状等が同一で且つその様な細孔の集合状態が均一に出来ているとする構造モデル）しているわけではなく、色々な細孔が混在した多分散した構造をとる。しかし、本実施形態では議論を簡単にするため、現実に得られる炭素多孔膜を後述する様な単分散の立方体殻状又は立方体枠状の細孔からなる炭素多孔膜と近似し（以後、それぞれを順に立方体壁組細孔モデル、立方体軸組細孔モデルと称する）、その構造を構造パラメータで規定することができるものとする。 (Assumption 1)
An actual carbon porous membrane has a monodisperse pore structure (a structure model in which the pore diameter, wall thickness or column thickness, shape, etc. of the pores are the same and the aggregate state of such pores is uniform. It has a polydispersed structure in which various pores are mixed. However, in this embodiment, in order to simplify the discussion, the carbon porous film actually obtained is approximated to a carbon porous film composed of monodispersed cubic shell-shaped or cubic frame-shaped pores as described later (hereinafter, respectively). Are sequentially referred to as a cubic wall group pore model and a cubic axis group pore model), and the structure thereof can be defined by structural parameters.
（前提２）
　室温における、黒鉛（ｇ－Ｃ）の密度Ｗ、非晶質炭素（ａ－Ｃ）の密度の値は、それぞれ、Ｗが２．２５～２．２６ｇ／ｃｍ３（本実施形態ではＷ＝２．２５ｇ／ｃｍ３とする）、ａ－Ｃの密度が１．８～２．１ｇ／ｃｍ３である。したがって、実際の炭素の密度はその結晶化度に応じて１．８～２．２６ｇ／ｃｍ３の範囲内の値を取る。 (Assumption 2)
The values of the density W of graphite (gC) and the density of amorphous carbon (aC) at room temperature are 2.25 to 2.26 g / cm 3 (W = 2 in this embodiment), respectively. and .25g / cm 3), the density of a-C is 1.8 ~ 2.1g / cm 3. Therefore, the actual density of carbon takes a value within the range of 1.8 to 2.26 g / cm 3 depending on the crystallinity.
　このように、現実の炭素多孔膜の細孔の壁又は柱を構成する炭素は、全て黒鉛の結晶で形成されているという訳ではないが、本実施形態では黒鉛の微結晶が無配向に凝集した多結晶体で形成されているものとする。炭素の結晶化度が低く、その密度が２．２５ｇ／ｃｍ３より小さければ、後述の［追記］で説明するように壁厚又は柱太さｄ或いは実質的な壁厚ｄＮ又は柱太さｄＮ１/２を、その密度における炭素の光学定数（特にｋ）に応じて大きくすることができる。 As described above, the carbon constituting the pore wall or column of the actual carbon porous film is not all formed of graphite crystals, but in this embodiment, the graphite microcrystals aggregate in a non-oriented manner. It is assumed that it is formed of a polycrystalline body. If the crystallinity of the carbon is low and the density is less than 2.25 g / cm 3 , the wall thickness or column thickness d, or the substantial wall thickness dN or column thickness dN, as will be described later in [Appendix]. 1/2 can be increased depending on the optical constant (particularly k) of the carbon at that density.
　（前提１）及び（前提２）に基づき、本実施形態の炭素多孔膜の細孔構造モデルとして、図４に示すような壁厚又は柱太さｄで、一辺の長さＬ０の立方体殻状又は立方体枠状の細孔（細孔径Ｌ）が、厚み方向にＮ個積み重なった構造を考え、これをそれぞれ順に立方体壁組細孔モデル、立方体軸組細孔モデルと称する。なお、立方体を敷き詰めた各層は、厚み方向に各立方体の四隅の頂点が、隣接する立方体の面の中心に位置するように厚み方向にズレながら積み重なっているものとする。細孔構造モデルを仮定したことで、Ｌ、Ｌ０、ｄの間、膜厚Ｄ、細孔の積層数Ｎ、細孔サイズパラメータα、ｄの間には、それぞれ
           Ｌ０＝Ｌ＋ｄ　…（１０）
           Ｄ＝Ｎαλ＋（Ｎ＋１）ｄ　…（１１）
の関係が成立する。 Based on (Premise 1) and (Premise 2), as a pore structure model of the carbon porous membrane of the present embodiment, a cubic shell shape having a wall thickness or a column thickness d as shown in FIG. Alternatively, a structure in which N pieces of cubic frame-shaped pores (pore diameter L) are stacked in the thickness direction is referred to as a cubic wall group pore model and a cubic axis group pore model, respectively. It is assumed that the layers in which the cubes are spread are stacked while being shifted in the thickness direction so that the apexes of the four corners of each cube are located in the center of the surface of the adjacent cube in the thickness direction. Assuming a pore structure model, L0 = L + d (10) between L, L0, d, film thickness D, number N of pores, and pore size parameters α, d.
D = Nαλ + (N + 1) d (11)
The relationship is established.
　更に、本実施形態の多孔膜の構造を、後述する第１及び第２構造パラメータを用いて規定することができ、各構造パラメータの間には、立方体壁組細孔モデルに関連して式（１２）～式（１４）の関係が、立方体軸組細孔モデルに関連して式（１５）～式（１７）の関係が成立する。
           Ｎ＝－１＋｛（Ｗ－ρ）１／３／Ｗ１／３｝＋｛Ｄ（Ｗ－ρ）１／３／αλＷ１／３｝　…（１２）
           ｄ＝αλ｛－１＋Ｗ１／３／（Ｗ－ρ）１／３｝　…（１３）
           ρ＝Ｗ［（Ｌ０３－Ｌ）／Ｌ０３］＝Ｗ［｛（１＋αλ／ｄ）３－（αλ／ｄ）３｝／（１＋αλ／ｄ）３］　…（１４）
           Ｎ＝８．３２×１０－１｛Ｄ／（αλ）｝－１０．６４｛ρ｝＋３．５４×１０－２｛Ｄ１／２｝＋７．６５×１０－１　…（１５）
           ｄ＝７．９０×１０－１｛ραλ｝＋８．４３×１０－１｛（αλ）１／２｝－７．９３×１０－１｛ρ－１／３｝－７．６０×１０－１　…（１６）
           ρ＝Ｗ［｛８（ｄ／２）２・（Ｌ＋ｄ／２）＋４（ｄ／２）２・Ｌ｝／Ｌ０３］＝Ｗ（１＋３αλ／ｄ）／（１＋αλ／ｄ）３　…（１７） Furthermore, the structure of the porous membrane of the present embodiment can be defined using first and second structure parameters described later, and between each structure parameter, an equation ( 12) to (14) are related to the cubic axis pore model, and the relationships of (15) to (17) are established.
N = −1 + {(W−ρ) 1/3 / W 1/3 } + {D (W−ρ) 1/3 / αλW 1/3 } (12)
d = αλ {−1 + W 1/3 / (W−ρ) 1/3 } (13)
ρ = W [(L0 3 −L) / L0 3 ] = W [{(1 + αλ / d) 3 − (αλ / d) 3 } / (1 + αλ / d) 3 ] (14)
N = 8.32 × 10 −1 {D / (αλ)}-10.64 {ρ} + 3.54 × 10 −2 {D 1/2 } + 7.65 × 10 −1 (15)
d = 7.90 × 10 -1 {ραλ } + 8.43 × 10 -1 {(αλ) 1/2} -7.93 × 10 -1 {ρ -1/3} -7.60 × 10 -1 ... (16)
ρ = W [{8 (d / 2) 2 · (L + d / 2) +4 (d / 2) 2 · L} / L0 3 ] = W (1 + 3αλ / d) / (1 + αλ / d) 3 (17)
　立方体壁組細孔モデルに関して、式（１１）及び式（１４）は、第１構造パラメータ群を用いて第２構造パラメータ群を、式（１２）及び式（１３）は、第２構造パラメータ群を用いて第１構造パラメータ群を表したものである。 Regarding the cubic wall set pore model, Equations (11) and (14) use the first structure parameter group to represent the second structure parameter group, and Equations (12) and (13) represent the second structure parameter group. Represents the first structural parameter group.
　立方体軸組細孔モデルに関して、式（１１）及び式（１７）は、第１構造パラメータ群を用いて第２構造パラメータ群を、式（１５）及び式（１６）は、第２構造パラメータ群を用いて第１構造パラメータ群を表したものである。 Regarding the cubic axis pore model, Equations (11) and (17) use the first structure parameter group to represent the second structure parameter group, and Equations (15) and (16) represent the second structure parameter group. Represents the first structural parameter group.
［構造パラメータ群］
　本実施形態における炭素多孔体膜の好ましい構造は、次の３つの物性値、Ｔ、Δ、Ｄの各基準値に応じて決まる。そして、その炭素多孔膜の構造は、細孔径（Ｌ）又は細孔サイズパラメータ（α）、細孔を形成する壁厚又は柱太さ（ｄ）、膜厚方向への細孔の積層数（Ｎ）を第１構造パラメータ群として、更にＬ（又はα）、Ｄ、更にρ（ａｐ）又はρと記載する炭素多孔膜の見かけ密度を第２構造パラメータ群として、これらの構造パラメータで規定することができるものとする。第１構造パラメータ群は、ミクロ的な構造パラメータであり、炭素多孔膜の構造を規定するには都合がよいが、直接・間接的に計測・観測するのは困難であり、製造プロセス上でこれらの値を用いて膜の構造を制御・規定するのは難しい。第２構造パラメータ群は、マクロ的な構造パラメータであり、直接・間接的に計測・観測するのは比較的容易であり、製造プロセス上でこれらの値を用いて構造を制御し易いが、これらの値から細孔構造モデルを仮定せずにミクロ的な構造を一意的に決定することはできない。 [Structural parameters]
The preferred structure of the carbon porous membrane in the present embodiment is determined according to the following three physical property values, T, Δ, and D reference values. And the structure of the carbon porous membrane includes the pore diameter (L) or the pore size parameter (α), the wall thickness or column thickness (d) forming the pores, and the number of pores stacked in the film thickness direction ( N) is defined as the first structural parameter group, and the apparent density of the carbon porous membrane described as L (or α), D, and ρ (ap) or ρ is defined as the second structural parameter group, and these structural parameters are defined. It shall be possible. The first structural parameter group is a microscopic structural parameter, which is convenient for defining the structure of the carbon porous membrane, but it is difficult to measure and observe directly and indirectly, and these are difficult in the manufacturing process. It is difficult to control and define the structure of the film using the value of. The second structural parameter group is a macroscopic structural parameter, and it is relatively easy to measure and observe directly and indirectly, and it is easy to control the structure using these values in the manufacturing process. A microscopic structure cannot be uniquely determined without assuming a pore structure model from the value of.
　両者の構造パラメータ群の間には、炭素多孔膜の構造モデルを仮定すれば、立方体壁組細孔モデルでは式（１２）～式（１４）が、立方体軸組細孔モデルでは式（１５）～式（１７）のような具体的関係が成立するが、厳密な対応を常にとることは不可能である。 If a structural model of the carbon porous membrane is assumed between the two structural parameter groups, Equation (12) to Equation (14) are obtained in the cubic wall-assembled pore model, and Equation (15) is obtained in the cubic shaft-assembled pore model. Although a concrete relationship as shown in Equation (17) is established, it is impossible to always take a strict correspondence.
　本実施形態では、適宜両構造パラメータ群を用いて内容を説明し、両者で矛盾が生じた場合は、基準値を満足する範囲内で、現実に炭素多孔膜の構造を規定しやすい第２構造パラメータ群を優先して用いる。 In the present embodiment, the contents are described using both structural parameter groups as appropriate, and when there is a contradiction between the two, the second structure in which the structure of the carbon porous membrane can be easily specified within a range that satisfies the reference value. The parameter group is used with priority.
［細孔径Ｌ、細孔半径ｒ］
　細孔径（Ｌ）とは、ガス吸着式細孔分布測定法の吸着等温線から求められる細孔分布曲線の山のピーク細孔半径ｒ（ｐｅａｋ）と、最大ピーク半径ｒ（ｍａｘ）（細孔分布の山と細孔分布のベースの交点において、大きい側の細孔半径値を指す）の値を２倍した値（２倍値と称する）をそれぞれＬ（ｐｅａｋ）、Ｌ（ｍａｘ）とし、単位は［ｎｍ］とする。なお、ｒ（ｍａｘ）、Ｌ（ｍａｘ）は、Δの各基準の上限を議論する場合に用い、それ以外の場合、特に断らなければ、Ｌ（ｐｅａｋ）をＬ、ｒ（ｐｅａｋ）をｒとして用いる。実験的・経験的には、林順一、堀河俊英、炭素、Ｎｏ．２３６、１５－２１（２００９）［以下、参考文献Ａとする］の図６、図８に記載のように、ｒ（ｍａｘ）は、細孔分布図の横軸をｒの対数目盛で、縦軸を積分細孔容積のｄＶ／ｄ［Ｌｏｇ（ｒ）］とした細孔分布曲線において、概ねｒ（ｐｅａｋ）の１．５～３倍程度になることが多い。また、細孔分布の山が低く、ｒ（ｍａｘ）が分かり難い場合は、ｒ（ｐｅａｋ）をｒ（ｍａｘ）の代替値とする。 [Pore diameter L, pore radius r]
The pore diameter (L) is the peak peak radius r (peak) of the peak of the pore distribution curve obtained from the adsorption isotherm of the gas adsorption type pore distribution measurement method, and the maximum peak radius r (max) (pore L (peak) and L (max) are values obtained by doubling the values of the distribution radius and the pore distribution base (pointing to the larger pore radius value) (referred to as double values), respectively. The unit is [nm]. Note that r (max) and L (max) are used when discussing the upper limit of each criterion of Δ, and otherwise L (peak) is L and r (peak) is r unless otherwise specified. Use. Experimentally and empirically, Junichi Hayashi, Toshihide Horikawa, Carbon, No. 236, 15-21 (2009) [hereinafter referred to as Reference A], as shown in FIG. 6 and FIG. 8, r (max) is a logarithmic scale of r on the horizontal axis of the pore distribution diagram. In the pore distribution curve whose axis is dV / d [Log (r)] of the integral pore volume, it is often about 1.5 to 3 times r (peak). Further, when the peak of the pore distribution is low and r (max) is difficult to understand, r (peak) is set as an alternative value for r (max).
　ガス吸着式細孔分布測定にあたっては、通常炭化物試料を予め２００～２５０℃で２～１５時間真空加熱した後、液体窒素温度における窒素の吸脱着等温測定を行い、その吸脱着等温線からＤＨ解析法又はＢＪＨ解析法にて細孔分布曲線を求める。本実施形態では、細孔径を求めるためにこの方法を用いる。 In gas adsorption type pore distribution measurement, usually a carbide sample is heated in vacuum at 200-250 ° C for 2-15 hours in advance, then nitrogen adsorption / desorption isothermal measurement at liquid nitrogen temperature is performed, and DH analysis is performed from the adsorption / desorption isotherm. The pore distribution curve is obtained by the method or the BJH analysis method. In this embodiment, this method is used to determine the pore diameter.
［細孔サイズパラメータα］
　細孔サイズパラメータ（α）とは、細孔径をＬ、露光に用いるＥＵＶ光の波長をλとした時、
           α＝Ｌ／λ　…（１８）
で定義される値であり、細孔径をλに対する倍数で表わしたものである。なお、本件のαは、通常のＭｉｅ散乱理論で用いられるサイズパラメータΛ（≡２πγ／λ＝πα、ここでγは球状散乱体の半径、πは円周率である）の、約１／３となっている。 [Pore size parameter α]
The pore size parameter (α) means that when the pore diameter is L and the wavelength of EUV light used for exposure is λ,
α = L / λ (18)
The pore diameter is expressed as a multiple of λ. In this case, α is about 1/3 of the size parameter Λ (≡2πγ / λ = πα, where γ is the radius of the spherical scatterer and π is the pi) used in the usual Mie scattering theory. It has become.
　なお、立方体壁組細孔モデルでは、個々の細孔が壁で区切られているため、細孔径は実質的に定義できる。立方体軸組細孔モデルでは、個々の細孔は連結しており、図４（ｂ）で示されるように、あくまでも形式的（仮想的）に区分けされた値である。 In the cubic wall set pore model, the pore diameter can be substantially defined because the individual pores are separated by walls. In the cubic axis set pore model, the individual pores are connected, and as shown in FIG. 4B, the values are strictly classified (virtual).
［細孔の壁厚又は柱太さｄ］
　本実施形態における細孔の壁厚又は柱太さ（ｄ）とは、立方体壁組細孔モデルでは炭素多孔膜を構成する個々の細孔を区切っている（細孔の障壁となっている）炭素壁の平均的な厚みのことであり、立方体壁組の壁の厚みのことである。立方体軸組細孔モデルでは、炭素多孔膜を構成する細孔と細孔とを形式的に区分する炭素棒（柱）の平均的な太さのことであり、立方体の枠の太さのことである。単位は［ｎｍ］とする。 [Wall Thickness or Column Thickness d]
The pore wall thickness or column thickness (d) in the present embodiment delimits individual pores constituting the carbon porous membrane in the cubic wall set pore model (becomes a pore barrier). It is the average thickness of the carbon wall, and the thickness of the wall of the cubic wall set. In the cubic axis pore model, the average thickness of carbon rods (columns) that formally divide the pores that make up the carbon porous membrane, and the thickness of the cubic frame It is. The unit is [nm].
　ｄは、透過型電子顕微鏡（ＴＥＭ）又は走査型電子顕微鏡（ＳＥＭ）を用いて、多孔膜の断面写真を撮影し、それを画像処理して求めることができる。しかし、高倍率での観察自体が極めて困難であること、更に断面写真から得られる情報自体が局所的で、多孔膜の平均的な壁厚となっているか否か疑わしいことから、本実施形態では、立方体壁組細孔モデルでは式（１３）により、立方体軸組細孔モデルでは式（１６）により、α、ρ（ａｐ）から算出された値をｄとする。 D can be obtained by taking a cross-sectional photograph of the porous film using a transmission electron microscope (TEM) or a scanning electron microscope (SEM) and processing the photograph. However, since observation at a high magnification itself is extremely difficult, and further, it is doubtful whether the information itself obtained from the cross-sectional photograph is local and the average wall thickness of the porous film is used. The value calculated from α and ρ (ap) by Equation (13) for the cubic wall group pore model and by Equation (16) for the cubic axis group pore model is d.
　ｄの値は、炭素原子の大きさが約０．３３ｎｍ、黒鉛（グラフェンシートの積層体と見なせる）の層間距離が０．３３５ｎｍであることを考慮すると、１枚のグラフェンシートの厚み約０．３３５ｎｍがｄの下限値となる。しかし、グラフェンシート１層や２層（ｄ＝約０．６７ｎｍ）では、細孔径が大きい場合（例えばα＞４）や、ペリクル膜に大きな力がかかる場合等は、壁強度又は柱強度（膜の曲げ剛性）として不十分なため、現実的にはグラフェンシート４層（ｄ＝約１．３５ｎｍ）以上が好ましい。もちろん、細孔径が小さい場合（例えばα＜１）や、膜に大きな力がかからない場合は、ｄを０．３３５ｎｍに近づけることができる。 Considering that the size of carbon atoms is about 0.33 nm and the interlayer distance of graphite (which can be regarded as a laminate of graphene sheets) is 0.335 nm, the value of d is about 0. 335 nm is the lower limit of d. However, in the graphene sheet 1 layer or 2 layers (d = about 0.67 nm), when the pore diameter is large (for example, α> 4) or when a large force is applied to the pellicle film, the wall strength or the column strength (film strength) In reality, a graphene sheet having four layers (d = 1.35 nm) or more is preferable. Of course, when the pore diameter is small (for example, α <1) or when a large force is not applied to the membrane, d can be brought close to 0.335 nm.
［細孔の積層数Ｎ］
　細孔の積層数（Ｎ）とは、細孔径Ｌの細孔の、膜厚方向への積層数のことである。本実施形態では、立方体壁組細孔モデルでは式（１２）により、立方体軸組細孔モデルでは式（１５）により、α、ρ（ａｐ）、Ｄから算出された値をＮとする。Ｎは、言葉の定義上、Ｎ≧１の整数となるべきだが、正の実数値も許すものとする。少数点以下の数値の端数部分は、単分散した立方体殻状又は立方体枠状の細孔が綺麗に積み重なった細孔構造モデルからのズレを反映しているものと考える。 [Number of pores N]
The number of pores (N) is the number of pores having a pore diameter L in the film thickness direction. In the present embodiment, N is a value calculated from α, ρ (ap), and D according to Equation (12) in the cubic wall group pore model and according to Equation (15) in the cubic axis group pore model. N should be an integer of N ≧ 1 in the definition of the word, but a positive real value is allowed. The fractional part of the numerical value below the decimal point is considered to reflect the deviation from the pore structure model in which monodispersed cubic shell-like or cubic frame-like pores are neatly stacked.
［見かけ密度ρ（ａｐ）、算術的な見かけ密度ρ］
　見かけ密度ρ（ａｐ）とは、多孔膜内部に細孔がないものとしたときの膜体積を用いた密度であり、膜の外形寸法から求められる膜の体積Ｖと膜の質量Ｇとの比、Ｇ／Ｖとして算出した値である。一方、算術的な見かけ密度ρとは、細孔構造モデルのもと、本実施形態では、立方体壁組細孔モデルでは式（１４）により、立方体軸組細孔モデルでは式（１７）により、α、ρ（ａｐ）、Ｄから算出された値をρとする。（前提１）及び（前提２）を仮定しているため、以下、ρ（ａｐ）＝ρとして両者を区別せずに扱う。単位は［ｇ／ｃｍ３］とする。 [Apparent density ρ (ap), Arithmetic apparent density ρ]
The apparent density ρ (ap) is a density using the membrane volume when it is assumed that there are no pores inside the porous membrane, and the ratio between the membrane volume V and the membrane mass G obtained from the outer dimensions of the membrane. , G / V. On the other hand, the arithmetic apparent density ρ is based on the pore structure model, in the present embodiment, according to the equation (14) for the cubic wall assembly pore model and the equation (17) for the cubic axis assembly pore model. A value calculated from α, ρ (ap), and D is ρ. Since (Assumption 1) and (Assumption 2) are assumed, ρ (ap) = ρ is treated without distinction between the two. The unit is [g / cm 3 ].
［膜厚Ｄ］
　膜厚（Ｄ）とは、通常の意味で用いられる、シート、フィルム、膜の厚みのことである。本実施形態の厚みの測定は、電子顕微鏡（ＳＥＭ）を用いて、非接触で多孔膜を１ｍｍ以上の間隔をあけて１０点以上撮影し、その寸法を平均した値として求めることができる。単位は、通常［ｎｍ］を用い、必要に応じて［μｍ］も用いることとする。 [Film thickness D]
The film thickness (D) is the thickness of a sheet, film, or film used in the usual sense. The measurement of the thickness of this embodiment can be obtained as a value obtained by averaging 10 or more images of a porous film in a non-contact manner with an interval of 1 mm or more using an electron microscope (SEM). The unit is usually [nm], and [μm] is also used as necessary.
［細孔形状］
　多孔膜の平均的な細孔形状は、参考文献Ａ、松岡秀樹、結晶学会誌、Ｎｏ．４１、２１３－２２６（１９９９）、西川恵子、炭素、Ｎｏ．１９１、７１－７６（２０００）に記載されたように、小角Ｘ線散乱（ＳＡＸＳ）の、Ｄｅｂｙｅ－Ｐｏｒｏｄ領域での散乱強度解析から求めることができる。すなわち、Ｘ線散乱強度Ｉを散乱ベクトルｓの関数として、両対数プロットした際、その直線の傾きが－４、－２、－１になれば、細孔の形状がそれぞれ球状、円盤状、円筒状であることを意味する。 [Pore shape]
The average pore shape of the porous membrane is described in Reference A, Hideki Matsuoka, Journal of Crystallographic Society, No. 41, 213-226 (1999), Keiko Nishikawa, Carbon, No. 191, 71-76 (2000), it can be obtained from the scattering intensity analysis in the Debye-Porod region of small angle X-ray scattering (SAXS). That is, when the logarithmic plot of the X-ray scattering intensity I as a function of the scattering vector s is a logarithmic slope of −4, −2, and −1, the pore shape is spherical, disk-shaped, cylindrical, respectively. Means that
２．本実施形態のペリクル膜とその製造方法
２－１．本実施形態のペリクル
　本実施形態のペリクル膜について、以下に［技術ポイント］毎に詳細な説明を行う。 2. 2. Pellicle membrane of this embodiment and method for manufacturing the pellicle membrane 2-1. Pellicle of this embodiment The pellicle film of this embodiment will be described in detail below for each [technical point].
［技術ポイント１］
　技術ポイント１は、ペリクル膜が多孔膜であることである。Ｍｉｅの散乱理論（Ｍｉｅ散乱自体は球形粒子による散乱であるが、定性的には形状は問わないものとする）では、球状粒子（球状細孔）による光散乱は、粒子（細孔）の直径（細孔径）を２γ、入射光の波長をλとし、粒径サイズパラメータΛ（＝２πγ／λ）を用いたとき、Λが１より十分に小さい（Λ＜＜１）場合はレイリー散乱が生じ、Λがほぼ１に近い（Λ≒１）の場合はＭｉｅ散乱が生じ、Λが１より十分に大きい（Λ＞＞１）場合は幾何学的散乱が生じるとされている。したがって、細孔径がΛ≧１の多孔体（多孔膜）であると、露光の際に光が入射したとき、光が細孔壁又は柱と細孔部の界面で散乱され、十分な透過率が得られないだけでなく、マスクの回路像を正しくウエハ上に結像することができないと考えられていた（上記特許文献６、特許文献７参照）。 [Technical point 1]
The technical point 1 is that the pellicle membrane is a porous membrane. In Mie's scattering theory (Mie scattering itself is scattering by spherical particles, but qualitatively the shape is not limited), light scattering by spherical particles (spherical pores) is the diameter of the particles (pores). When the pore size is 2γ, the wavelength of incident light is λ, and the particle size parameter Λ (= 2πγ / λ) is used, Rayleigh scattering occurs when Λ is sufficiently smaller than 1 (Λ << 1). , Λ is almost 1 (Λ≈1), Mie scattering occurs, and when Λ is sufficiently larger than 1 (Λ >> 1), geometric scattering occurs. Therefore, when the pore diameter is a porous body (porous film) with Λ ≧ 1, when light is incident upon exposure, the light is scattered at the interface between the pore wall or the column and the pore portion, and sufficient transmittance is obtained. It is considered that the circuit image of the mask cannot be correctly formed on the wafer (see Patent Documents 6 and 7).
　しかし、細孔径がΛ≧１以上の多孔体（多孔膜）であっても、細孔壁又は柱の屈折率が細孔部、すなわち真空の屈折率１．０と等しい場合又は細孔壁又は柱の屈折率と細孔部（細孔内の空間）の屈折率との差Δｎが０に近い場合、例えばΔｎ＝０．０４以下の場合、光は細孔壁と細孔部との界面を認識できず、ほとんど反射・散乱されることなく直進することができることが分かった。 However, even in the case of a porous body (porous film) having a pore diameter of Λ ≧ 1 or more, when the refractive index of the pore wall or column is equal to the pore portion, that is, the refractive index of vacuum 1.0, When the difference Δn between the refractive index of the column and the refractive index of the pore (space in the pore) is close to 0, for example, Δn = 0.04 or less, the light is the interface between the pore wall and the pore. It was found that it was possible to go straight with almost no reflection or scattering.
　図１に、光学定数（屈折率ｎ、消光係数ｋ）の値と膜厚Ｄの値とを仮定した平膜（非多孔膜）の、光学定数と入射角θ＝６°における透過率Ｔ及び反射率Ｒとの関係を示したグラフを示す。図１に示すグラフは、「Ｇｒａｔｉｎｇ　Ｓｏｌｖｅｒ　Ｄｅｖｅｌｏｐｍｅｎｔ　Ｃｏｍｐａｎｙ」から市販されている「Ｇ－Ｓｏｌｖｅｒ格子分析ソフトウエアツール（Ｇ－Ｓｏｌｖｅｒ）」を用いて計算したものである。図１（ａ）は、Ｄ＝１００ｎｍ、ｎ＝１．０の平膜の、Ｔ及びＲのｋに対する依存性を、図１（ｂ）は、Ｄ＝１００ｎｍ、ｋ＝０．０００５の平膜の、Ｔ及びＲのｎに対する依存性を示したグラフである。図１（ａ）において、点線で囲む領域は、Ｔ≧８４％を確保できるｋの領域を示している。図１（ａ）より、ｋの僅かな変化でＴが大きく変化し、非多孔膜で膜厚が１００ｎｍ程度である場合、少なくともｋは１０－３のオーダー以下でなければＴ≧Ｔ１＝８４％が得られないことが分かる。 FIG. 1 shows the optical constant and transmittance T at an incident angle θ = 6 ° of a flat film (non-porous film) assuming the values of optical constants (refractive index n, extinction coefficient k) and film thickness D. The graph which showed the relationship with the reflectance R is shown. The graph shown in FIG. 1 is calculated using a “G-Solver grid analysis software tool (G-Solver)” commercially available from “Grating Solver Development Company”. FIG. 1A shows the dependence of T and R on k for a flat film with D = 100 nm and n = 1.0, and FIG. 1B shows the flat film with D = 100 nm and k = 0.0005. Is a graph showing the dependence of T and R on n. In FIG. 1A, a region surrounded by a dotted line indicates a region k that can secure T ≧ 84%. From FIG. 1 (a), when T changes significantly with a slight change of k and the film thickness is about 100 nm with a non-porous film, T ≧ T1 = 84% unless at least k is less than the order of 10 −3. It can be seen that cannot be obtained.
　また、図１（ｂ）において、点線で囲む領域は、反射率Ｒ≦０．２％に抑えられるｎの領域を示している。図１（ｂ）より、上述したようにｎ＝０．９４～１．４、すなわちΔｎ≦０．０４では界面からの反射が抑えられ、Ｔが最大となることが分かる。 Further, in FIG. 1B, the region surrounded by a dotted line indicates an n region where the reflectance R ≦ 0.2%. As can be seen from FIG. 1B, when n = 0.94 to 1.4, that is, Δn ≦ 0.04, reflection from the interface is suppressed and T is maximized.
　ペリクル膜として多孔膜を用いることの第１の利点は、従来のＳｉ単結晶平膜における５０～１００ｎｍ膜の厚み制限が大幅に緩和され、後述するようにＴがＴ１以上且つΔがΔ１以下であり、且つＤが１００ｎｍ以上（Ｄ１以上）、更には３００ｎｍ以上（Ｄ２以上）、５００ｎｍ以上（Ｄ３以上）とすることができることである。 The first advantage of using a porous film as the pellicle film is that the thickness limitation of the 50 to 100 nm film in the conventional Si single crystal flat film is greatly relaxed, and T is T1 or more and Δ is Δ1 or less as described later. And D can be 100 nm or more (D1 or more), 300 nm or more (D2 or more), or 500 nm or more (D3 or more).
　ペリクル膜として多孔膜を用いることの第２の利点は、ダンボール板と呼ばれる波板状の多孔性包装紙材が、同重量同面積の平膜状紙板に比べて曲げ剛性が大きいように、多孔膜の方が、同重量同面積の平膜（非多孔膜）に比べて、曲げ剛性が大きくなることである。 A second advantage of using a porous film as a pellicle film is that a corrugated cardboard-like porous wrapping paper material has a higher bending rigidity than a flat film-like paper board having the same weight and the same area. The film has higher bending rigidity than a flat film (non-porous film) having the same weight and the same area.
　ダンボール板がストロー状の１次元的に伸びた孔を内部に有する多孔性の構造体であるのに対し、本実施形態の多孔膜は３次元的な多孔性の構造であるため、より応力集中が起こりにくく、膜の曲げ剛性が更に高いと言える。この結果、本実施形態の多孔膜をペリクル膜と使用した場合、同面積同重量の他素材の平膜に比べ、自重で膜がたわむ程度が小さい。 Whereas the corrugated cardboard plate is a porous structure having a straw-like one-dimensionally extending hole inside, the porous film of the present embodiment has a three-dimensional porous structure, so that the stress concentration is further increased. It can be said that the bending rigidity of the film is even higher. As a result, when the porous film of the present embodiment is used as a pellicle film, the degree of bending of the film by its own weight is small compared to a flat film of another material having the same area and weight.
［技術ポイント２］
　技術ポイント２は、多孔膜が炭素からなることである。多孔膜として炭素を用いることの第１の利点は、多孔膜化した炭素の、光学定数としての優位性である。一般に、膜を構成する元素の種類と、膜の結晶・非晶の構造の割合による密度が決まると、ＥＵＶ領域における光学定数ｎ、ｋを上記非特許文献１から求めることができる。実際には、具体的な数値の算出には、ＣＸＲＯ（Ｔｈｅ Ｃｅｎｔｅｒ ｆｏｒ Ｘ－ｒａｙ Ｏｐｔｉｃｓ）のウェブページ＜ｈｔｔｐ：／／ｈｅｎｋｅ．ｌｂｌ．ｇｏｖ／ｏｐｔｉｃａｌ＿ｃｏｎｓｔａｎｔｓ／ｇｅｔｄｂ２．ｈｔｍｌ＞を用いた。 [Technical point 2]
Technical point 2 is that the porous film is made of carbon. The first advantage of using carbon as the porous film is the superiority of the carbon in the porous film as an optical constant. In general, when the density depending on the kind of elements constituting the film and the ratio of the crystalline / amorphous structure of the film is determined, the optical constants n and k in the EUV region can be obtained from Non-Patent Document 1. Actually, for the calculation of specific numerical values, the web page of CXRO (The Center for X-ray Optics) <http: // henke. lbl. gov / optical_constants / getdb2. html> was used.
　密度として、非多孔体の密度（通常、単純に密度、真密度と呼ばれる）の値より小さい、多孔膜の見かけ密度ρを用いて求めたｎ、ｋは、結晶・非晶の構造とその割合が変わらないと仮定すれば、その値はそのρを有する多孔膜の光学定数と見なすことができる。ここで、見かけ密度ρとそのρにおける光学定数とを有する平膜（非多孔膜）を多孔膜代替平膜と称することとすれば、便宜的に細孔による散乱を無視した、種々のρを有する多孔膜代替平膜のｎ及びｋを、非特許文献１から求めることができる。 As the density, n and k obtained by using the apparent density ρ of the porous film, which is smaller than the density of the non-porous material (usually simply called the density or the true density), are the crystal / amorphous structure and its ratio. Assuming that does not change, the value can be regarded as the optical constant of the porous film having that ρ. Here, if a flat film (non-porous film) having an apparent density ρ and an optical constant at the ρ is referred to as a porous film alternative flat film, various ρs ignoring scattering by the pores for convenience. The n and k of the porous membrane alternative flat membrane that can be obtained can be obtained from Non-Patent Document 1.
　図２は、炭素Ｃ（密度２．２ｇ／ｃｍ３）、珪素Ｓｉ（密度２．３３ｇ／ｃｍ３）、炭化珪素ＳｉＣ（密度３．２ｇ／ｃｍ３）及び見かけ密度ρ＝０．６ｇ／ｃｍ３のＣの、ｎ及びｋの波長λに対する依存性を示したグラフである。図２に示されるように、Ｓｉ、ＳｉＣの光学定数がλ＝１２ｎｍ付近でＳｉのＬ吸収端による不連続変化が生じるのに対し、Ｃの光学定数は連続で、ｎは単調増加し、ｋは単調減少し、特にｋはλ≦１２ｎｍではＣ（ρ＝０．６ｇ／ｃｍ３）の方がＳｉ、ＳｉＣよりも小さな値となる。 FIG. 2 shows carbon C (density 2.2 g / cm 3 ), silicon Si (density 2.33 g / cm 3 ), silicon carbide SiC (density 3.2 g / cm 3 ), and apparent density ρ = 0.6 g / cm. 3 is a graph showing the dependence of C of 3 on the wavelength λ of n and k. As shown in FIG. 2, the optical constants of Si and SiC change discontinuously due to the L absorption edge of Si near λ = 12 nm, whereas the optical constant of C is continuous, n increases monotonously, and k Decreases monotonously. In particular, when λ ≦ 12 nm, C (ρ = 0.6 g / cm 3 ) is smaller than Si and SiC.
　図３は、Ｓｉ、ＳｉＣ及び種々の見かけ密度ρでのＣにおける、λ＝１３．６ｎｍ及びλ＝６．７ｎｍでの光学定数ｎ、ｋを示したグラフであるが、ＥＵＶ領域の光学定数は、使用する光の波長と物資の密度に関係し、例えば、λ＝６．７～１３．６ｎｍの波長範囲に対応して、Ｓｉ（２．３３ｇ／ｃｍ３）の場合、ｋが９．５×１０－３（λ＝６．７ｎｍ）～１．８×１０－３（λ＝１３．６ｎｍ）、ｎが０．９９（λ＝６．７ｎｍ）～１．０（λ＝１３．６ｎｍ）であるのに対し、炭素の場合、黒鉛（２．２５ｇ／ｃｍ３）では、ｋが７．６×１０－４（λ＝６．７ｎｍ）～７．２×１０－３（λ＝１３．６ｎｍ）、ｎが０．９９（λ＝６．７ｎｍ～０．９６（λ＝１３．６ｎｍ）となる。 FIG. 3 is a graph showing optical constants n and k at λ = 13.6 nm and λ = 6.7 nm for C at various apparent densities ρ, and the optical constants in the EUV region are In the case of Si (2.33 g / cm 3 ) corresponding to the wavelength range of light to be used and the density of materials, for example, corresponding to the wavelength range of λ = 6.7 to 13.6 nm, k is 9.5. × 10 −3 (λ = 6.7 nm) to 1.8 × 10 −3 (λ = 13.6 nm), n is 0.99 (λ = 6.7 nm) to 1.0 (λ = 13.6 nm) On the other hand, in the case of carbon, in the case of graphite (2.25 g / cm 3 ), k is 7.6 × 10 −4 (λ = 6.7 nm) to 7.2 × 10 −3 (λ = 13. 6 nm) and n are 0.99 (λ = 6.7 nm to 0.96 (λ = 13.6 nm).
　このことは、λ＝１３．６ｎｍ領域ではＳｉがペリクル膜を作製する上で黒鉛よりも適しているが、λ＝６．７ｎｍ領域ではむしろ黒鉛の方が優れていることを示している。 This indicates that Si is more suitable than graphite in producing a pellicle film in the λ = 13.6 nm region, but graphite is rather superior in the λ = 6.7 nm region.
　更に、炭素を本実施形態のように多孔膜化した場合、ρ＝０．６ｇ／ｃｍ３のＣでは、ｋが２．０×１０－４（λ＝６．７ｎｍ）～１．９×１０－３（λ＝１３．６ｎｍ）、ｎが１．０～０．９９となる。ρ＝０．４ｇ／ｃｍ３のＣでは、ｋが１．４×１０－４（λ＝６．７ｎｍ）～１．３×１０－３（λ＝１３．６ｎｍ）、ｎが１．０（λ＝６．７ｎｍ）～０．９９（λ＝１３．６ｎｍ）となる。ρ＝０．２ｇ／ｃｍ３のＣでは、ｋが６．８×１０－５（λ＝６．７ｎｍ）～６．４×１０－４（λ＝１３．６ｎｍ）、ｎが１．０（λ＝６．７ｎｍ）～１．０（λ＝１３．６ｎｍ）となる。ρ＝０．０８ｇ／ｃｍ３のＣでは、ｋが２．７×１０－５（λ＝６．７ｎｍ）～２．６×１０－４（λ＝１３．６ｎｍ）、ｎが１．０（λ＝６．７ｎｍ）～１．０（λ＝１３．６ｎｍ）となる。 Further, when carbon is formed into a porous film as in the present embodiment, k is 2.0 × 10 −4 (λ = 6.7 nm) to 1.9 × 10 6 for C with ρ = 0.6 g / cm 3. -3 (λ = 13.6 nm) and n is 1.0 to 0.99. For C with ρ = 0.4 g / cm 3 , k is 1.4 × 10 −4 (λ = 6.7 nm) to 1.3 × 10 −3 (λ = 13.6 nm), and n is 1.0 ( λ = 6.7 nm) to 0.99 (λ = 13.6 nm). For C with ρ = 0.2 g / cm 3 , k is 6.8 × 10 −5 (λ = 6.7 nm) to 6.4 × 10 −4 (λ = 13.6 nm), and n is 1.0 ( λ = 6.7 nm) to 1.0 (λ = 13.6 nm). For C with ρ = 0.08 g / cm 3 , k is 2.7 × 10 −5 (λ = 6.7 nm) to 2.6 × 10 −4 (λ = 13.6 nm), and n is 1.0 ( λ = 6.7 nm) to 1.0 (λ = 13.6 nm).
　このように、炭素は、多孔膜化し、見かけ密度を下げることで、λ＝６．７ｎｍ領域だけでなくλ＝１３．６ｎｍ領域でもＳｉと同等以上の低いｋと１．０に近いｎとを有することとなる。 In this way, carbon is converted into a porous film, and the apparent density is lowered, so that not only λ = 6.7 nm region but also λ = 13.6 nm region has a low k equal to or higher than Si and an n close to 1.0. Will have.
　多孔膜として炭素を用いることの第２の利点は、万が一ペリクル膜が破損し、マスク上に付着した際にも容易に除去可能であることである。例えば、高木紀明等、立命館大学研究報告書、立Ｓ２２－０３、「ＥＵＶリソグラフィ用マスク上のカーボン堆積実験：洗浄技術の評価」、老泉博昭、九州工業大学大学院工学研究科博士学位論文「極端紫外線（ＥＵＶ）を用いたリソグラフィ基礎技術」（平成１９年３月）で紹介されているように、有機分子を直接分解することができるＶＵＶ光（λ＝１７２ｎｍ）、ＥＵＶ光（λ＝１３．５ｎｍ）自体を用いて、活性酸素により酸化させて、一酸化炭素ＣＯ或いは二酸化炭素ＣＯ２とする反応（酸化法）や、原子状水素により還元させてメタン系炭化水素（ＣＨＸ）とする反応（還元法）により、ＥＵＶ用マスク上に付着した炭素を除去することができる。 A second advantage of using carbon as the porous film is that the pellicle film can be easily removed even if it is damaged and adhered to the mask. For example, Noriaki Takagi et al., Ritsumeikan University research report, Ritsu S22-03, “Carbon deposition experiment on EUV lithography mask: Evaluation of cleaning technology”, Hiroaki Oizumi, Ph.D. As introduced in “Basic Lithography Technology Using Ultraviolet (EUV)” (March 2007), VUV light (λ = 172 nm) and EUV light (λ = 13. 5 nm) itself is used to oxidize with active oxygen to carbon monoxide CO or carbon dioxide CO 2 (oxidation method), or to reduce with atomic hydrogen to methane hydrocarbon (CH X ) By the (reduction method), carbon adhering to the EUV mask can be removed.
　多孔膜として炭素を用いることの第３の利点は、既存の炭素多孔膜の製造方法を応用することで、目標とする細孔径、膜厚を有する多孔膜を作り易いことである。すなわち、「２．２　本実施形態のペリクル膜の製造方法」で述べるように、ゾル－ゲル転移を生じる有機化合物の溶液を用いて薄膜を成膜し、ゾル－ゲル法で溶媒を多量に含んだヒドロゲル状態を形成させ、その後、構造が潰れないように溶媒を乾燥除去させることで、多量に気泡を含む多孔体としてのエアロゲル膜を得られる。そして、エアロゲル膜を最終的に炭化して炭素エアロゲルとしての炭素多孔膜を得る方法や、分子構造中に化学反応過程や炭化過程で構造を固定化すると共に気泡が発生する高分子原料（有機化合物である）を用いた高分子溶液を作り、薄膜成膜後、化学反応や炭化反応させ、その過程で発生する気泡又は隙間を細孔とした炭素多孔膜を得る方法、或いはこれらの方法を組み合わせた方法が挙げられる。 A third advantage of using carbon as the porous film is that a porous film having a target pore diameter and film thickness can be easily produced by applying an existing carbon porous film manufacturing method. That is, as described in “2.2 Pellicle membrane manufacturing method of this embodiment”, a thin film is formed using a solution of an organic compound that causes a sol-gel transition, and a large amount of solvent is contained by the sol-gel method. By forming a hydrogel state and then drying and removing the solvent so that the structure is not crushed, an airgel film as a porous body containing a large amount of bubbles can be obtained. Finally, the airgel membrane is carbonized to obtain a carbon porous membrane as a carbon aerogel, or a polymer raw material (organic compound) that immobilizes the structure in the molecular structure during the chemical reaction process or carbonization process and generates bubbles. A method for obtaining a carbon porous film having pores or gaps generated in the process after a thin film is formed and then chemical reaction or carbonization reaction, or a combination of these methods. Method.
　薄膜化技術として、蒸着法とは異なり、高分子溶液を使ったスピンコート、ダイコート、グラビアコートといった非真空環境下でのウエット塗工法を用いて膜厚を容易に薄く制御したり、或いは、シリコンウエハの作製法のようにロッド状のものを薄く切削・研磨加工して薄膜化したりすることで、生産性の高い製造が可能となる。 As a thin film technology, unlike the vapor deposition method, the film thickness can be easily controlled using a wet coating method in a non-vacuum environment such as spin coating, die coating, and gravure coating using a polymer solution, or silicon. As in the wafer manufacturing method, a rod-shaped material is thinly cut and polished to form a thin film, thereby enabling high-productivity manufacturing.
　多孔膜として炭素を用いることの第４の利点は、熱的な特性と曲げ剛性が優れていることである。非晶質炭素（ａ－Ｃ）、黒鉛（ｇ－Ｃ）及びＳｉの融点、熱膨張係数は、それぞれ次のようになっている。すなわち、常圧下の融点は、炭素自体が全元素中最も高く、ａ－Ｃ、ｇ－Ｃには融点は存在せず、Ｓｉは１４１４℃であり、炭素の耐熱性が優れている。熱膨張係数は、ａ－Ｃが３．０×１０－６／Ｋ、ｇ－Ｃが３．２×１０－６／Ｋ、Ｓｉが３．９×１０－６／Ｋであり、炭素の熱寸法安定性が優れている。 A fourth advantage of using carbon as the porous film is that it has excellent thermal characteristics and bending rigidity. The melting point and thermal expansion coefficient of amorphous carbon (aC), graphite (gC) and Si are as follows. That is, the melting point under normal pressure is the highest among all elements, and a-C and g-C have no melting point, Si has 1414 ° C., and the heat resistance of carbon is excellent. The coefficient of thermal expansion is 3.0 × 10 −6 / K for aC , 3.2 × 10 −6 / K for gC, and 3.9 × 10 −6 / K for Si. Excellent dimensional stability.
　一方、膜の硬さ（物理強度）に相当する曲げ剛性は、炭素とＳｉのポアソン比が共に０．２程度であるため、ヤング率と膜厚Ｄの３乗との積に比例する。ａ－Ｃのヤング率が３０～３３ＧＰａ、ｇ－Ｃのヤング率が１４ＧＰａであるのに対し、Ｓｉのヤング率が１３０～１９０ＧＰａである。炭素よりＳｉの方が優れているが、実際は本実施形態では炭素多孔膜であり、膜厚ＤがＳｉ平膜の２．５倍～５倍以上に厚くすることができることから、ペリクル膜としては、本実施形態の炭素多孔膜の方が大きくなると考えられる。 On the other hand, the bending stiffness corresponding to the hardness (physical strength) of the film is proportional to the product of the Young's modulus and the cube of the film thickness D because the Poisson's ratio of carbon and Si is both about 0.2. The Young's modulus of aC is 30 to 33 GPa and the Young's modulus of gC is 14 GPa, whereas the Young's modulus of Si is 130 to 190 GPa. Si is superior to carbon, but in the present embodiment, it is actually a porous carbon film, and since the film thickness D can be made 2.5 to 5 times thicker than the Si flat film, The carbon porous membrane of this embodiment is considered to be larger.
［技術ポイント３］
　技術ポイント３は、課題を満たす炭素多孔膜を制約された構造パラメータを用いて規定できることである。 [Technical point 3]
The technical point 3 is that a carbon porous film that satisfies the problem can be defined using restricted structural parameters.
　炭素多孔膜の構造パラメータが、現実的な炭素膜の膜強度や製造上の経験値を反映した制約条件と、Ｔ、Δ、Ｄに関する基準値を満たす特定の範囲内にあれば、ＥＵＶリソグラフィに好適に用いられるペリクル膜を得られる。以下、順にステップを追って説明する。 If the structural parameters of the carbon porous membrane are within a specific range that satisfies the constraints that reflect the actual strength of the carbon membrane and experience values in manufacturing, and the reference values for T, Δ, and D, EUV lithography A pellicle film that is suitably used can be obtained. Hereinafter, steps will be described in order.
［構造パラメータ群と基準値（Ｔｉ、Δｉ、Ｄｉ、ｉ＝１～３）との関係］ 
（１）ステップ１
　Ｎ＝１層～５層の立方体壁組細孔モデル及び立方体軸組細孔モデルにおいて、ｄ、αを様々に変化させたモデルを作成した。非特許文献１から求めた炭素（２．２５ｇ／ｃｍ３）の、λ＝１３．５ｎｍにおける光学定数ｎ、ｋ（それぞれ、９．６１×１０－１、７．７０×１０－３）及びλ＝６．７５ｎｍにおける光学定数ｎ、ｋ（それぞれ、９．９１×１０－１、７．７０×１０－４）と、ＲＳｏｆｔ社製のＲＣＷＡ法による回折光学素子設計・解析ソフトウェアＤｉｆｆｒａｃｔＭＯＤを使用して、各モデルの入射角θ＝６°におけるＴ、Δ、Ｄを計算した。なお、Ｔは、０次の透過率のことであり、またΔは、全透過率から０次の透過率を差し引いた値のことである。 [Relationship between structural parameter group and reference values (Ti, Δi, Di, i = 1 to 3)]
(1) Step 1
In the N = 1 to 5 layer cubic wall group pore model and the cubic axis group pore model, models were prepared in which d and α were changed in various ways. The optical constants n and k (λ 9.61 × 10 −1 and 7.70 × 10 −3 ) and λ, respectively, of λ = 13.5 nm of carbon (2.25 g / cm 3 ) obtained from Non-Patent Document 1. = Optical constants n and k at 6.75 nm (9.91 × 10 −1 and 7.70 × 10 −4 , respectively) and diffractive optical element design / analysis software DiffractMOD by RCWA method manufactured by RSsoft The T, Δ, and D at the incident angle θ = 6 ° of each model were calculated. Note that T is the 0th-order transmittance, and Δ is the value obtained by subtracting the 0th-order transmittance from the total transmittance.
　なお、Ｔ、Δ、Ｄの計算には、上述のＤｉｆｆｒａｃｔＭＯＤを用いる方法以外に、前述のＧ－Ｓｏｌｖｅｒを用いる方法もある。前者は、計算が複雑で高度なため長い計算時間を要する反面、立方体壁組細孔モデル及び立方体軸組細孔モデルのどちらにも対応ができる。一方、後者は、計算が比較的に単純で計算時間も早い反面、立方体壁組細孔モデルのみに対応すること、また計算結果が１回通過時の透過率Ｔが７０～１００％の範囲でＴの値が最大１０％程度大きめになること、散乱量Δが０～１０％の範囲でΔの値が最大５％程度小さめになる。本実施形態では、特に断らなければ、どちらの細孔構造モデルにも適用できる前者を優先して計算法として用いることとする。 In addition to the above-described method using DiffractMOD, there is a method using G-Solver as described above for calculating T, Δ, and D. The former requires a long calculation time because the calculation is complicated and sophisticated, but can cope with both the cubic wall set pore model and the cube axis pore model. On the other hand, the latter is relatively simple and has a fast calculation time, but corresponds only to the cubic wall-assembled pore model, and the calculation result has a transmittance T of 70 to 100% in a single pass. The value of T becomes larger by about 10% at maximum, and the value of Δ becomes smaller by about 5% at maximum when the scattering amount Δ is in the range of 0 to 10%. In the present embodiment, unless otherwise specified, the former applicable to either pore structure model is preferentially used as a calculation method.
　得られた結果に対して、株式会社エスミから市販されているＥＸＣＥＬ多変量解析のソフトウエアツール（重回帰ソフト）を使用して重回帰分析を行ない、各細孔構造モデルにおける、第１構造パラメータ群及び第２構造パラメータ群の、炭素多孔膜のＴ及びΔへの影響を求めた。 The obtained results were subjected to multiple regression analysis using the EXCEL multivariate analysis software tool (multiple regression software) commercially available from Sumi Co., Ltd., and the first structural parameters in each pore structure model The influence of the group and the second structural parameter group on the T and Δ of the carbon porous membrane was determined.
＜ステップ１－１＞
　立方体壁組細孔モデルにおける、第１構造パラメータ群Ｎ、ｄ、αによるＴ、Δへの影響 <Step 1-1>
Influence of T, Δ by the first structural parameter group N, d, α in the cubic wall set pore model
　立方体壁組細孔モデルにおける、第１構造パラメータ群Ｎ、ｄ、αによる重回帰分析の結果、λ＝１３．５ｎｍでのＴに関する重回帰式は、
           Ｔ＝［－７．６５×１０－３｛α｝－１．５３×１０－２｛ｄＮ｝＋９．９５×１０－１］×１００　…（１９）
           自由度修正済決定係数Ｒ＊２＝０．９７
となり、標準偏回帰係数の絶対値の大小関係を利用して求めた各因子の依存率（各因子の標準偏回帰係数の絶対値を、全因子の標準偏回帰係数の絶対値の和で割った百分率の値とする）は、αが２８％、ｄＮが７２％となった。なお、Ｔに関する重回帰式は、ペリクル膜を２回通過する際の透過率が１回通過する場合の値をほぼ二乗する必要がある等を説明する上では理論的には好ましく、
           Ｉｎ（Ｔ）＝［－１．１３×１０－２｛α｝－２．０４×１０－２｛ｄＮ｝＋２．９３×１０－２］　…（２０）
           Ｒ＊２＝０．９５
とも近似できたが、Ｒ＊２の大きい式（１９）を以後の計算では用いた。 As a result of the multiple regression analysis by the first structural parameter group N, d, α in the cubic wall set pore model, the multiple regression equation for T at λ = 13.5 nm is
T = [− 7.65 × 10 −3 {α} −1.53 × 10 −2 {dN} + 9.95 × 10 −1 ] × 100 (19)
Degree-of-freedom corrected coefficient of determination R * 2 = 0.97
The dependence of each factor obtained using the magnitude relationship of the absolute value of the standard partial regression coefficient (the absolute value of the standard partial regression coefficient of each factor is divided by the sum of the absolute values of the standard partial regression coefficients of all factors. As a percentage, α was 28% and dN was 72%. Note that the multiple regression equation for T is theoretically preferable in order to explain that the transmittance when passing through the pellicle membrane twice needs to be almost squared, etc.
In (T) = [− 1.13 × 10 −2 {α} −2.04 × 10 −2 {dN} + 2.93 × 10 −2 ] (20)
R * 2 = 0.95
However, Equation (19) having a large R * 2 was used in the subsequent calculations.
　また、λ＝１３．５ｎｍでのΔに関する重回帰式は、
           Δ＝［５．０５×１０－４｛ｄＮα｝＋３．６６×１０－３］×１００　…（２１）
           Ｒ＊２＝０．９２
となった。 Also, the multiple regression equation for Δ at λ = 13.5 nm is
Δ = [5.05 × 10 −4 {dNα} + 3.66 × 10 −3 ] × 100 (21)
R * 2 = 0.92
It became.
　一方、λ＝６．７５ｎｍでのＴに関する重回帰式は、
           Ｔ＝［－１．９８×１０－３｛α｝－４．６８×１０－３｛ｄＮ｝＋１．０１］×１００　…（２２）
           Ｒ＊２＝０．９１
となり、各因子の依存率は、αが３４％、ｄＮが６６％となった。なお、Ｔに関する重回帰式は、
           Ｉｎ（Ｔ）＝［－２．１６×１０－３｛α｝－５．０５×１０－３｛ｄＮ｝＋１．２４×１０－２］　…（２３）
           Ｒ＊２＝０．９０
とも近似できたが、Ｒ＊２の大きい式（２２）を以後の計算では用いた。 On the other hand, the multiple regression equation for T at λ = 6.75 nm is
T = [− 1.98 × 10 −3 {α} −4.68 × 10 −3 {dN} +1.01] × 100 (22)
R * 2 = 0.91
Thus, the dependency rate of each factor was 34% for α and 66% for dN. The multiple regression equation for T is
In (T) = [- 2.16 × 10 -3 {α} -5.05 × 10 -3 {dN} + 1.24 × 10 -2] ... (23)
R * 2 = 0.90
However, equation (22) having a large R * 2 was used in the subsequent calculations.
　また、λ＝６．７５ｎｍでのΔに関する重回帰式は、
           Δ＝［１．４９×１０－４｛ｄＮα｝－１．４７×１０－４］×１００　…（２４）
           Ｒ＊２＝０．９４
となった。 Also, the multiple regression equation for Δ at λ = 6.75 nm is
Δ = [1.49 × 10 −4 {dNα} −1.47 × 10 −4 ] × 100 (24)
R * 2 = 0.94
It became.
　これらの結果より、立方体壁組細孔モデルにおいて、Ｔには、細孔の壁厚と細孔の積層数との積、すなわち、Ｎｄという膜を構成する材料の、膜厚方向への実質的な厚み（平膜の膜厚に相当する）が大きな影響を与え、細孔の大きさに対応するαは、前者の因子ほど影響は与えないことが分かる。一方、Δには、αＮｄと積の形であることから、αとＮｄとが同程度に影響を与えることが分かる。αは、物理的には細孔径Ｌ（＝λα）に対応しており、Δが細孔径の影響を受けやすいことを意味している。 From these results, in the cubic wall set pore model, T is the product of the pore wall thickness and the number of laminated pores, that is, the material of the film constituting Nd in the film thickness direction. It can be seen that a large thickness (corresponding to the thickness of the flat membrane) has a great influence, and α corresponding to the size of the pores has no influence as much as the former factor. On the other hand, since Δ is in the form of a product of αNd, it can be seen that α and Nd affect the same extent. α physically corresponds to the pore diameter L (= λα), meaning that Δ is easily affected by the pore diameter.
＜ステップ１－２＞
　立方体軸組細孔モデルにおける、第１構造パラメータ群Ｎ、ｄ、αによるＴ、Δへの影響 <Step 1-2>
Influence of T, Δ by the first structural parameter group N, d, α in the cubic frame pore model
　立方体軸組細孔モデルにおける、第１構造パラメータ群Ｎ、ｄ、αによる重回帰分析の結果、λ＝１３．５ｎｍでのＴに関する重回帰式は、
           Ｔ＝［６．０２×１０－３｛α｝－８．６９×１０－３｛ｄＮ１／２｝＋１．００］×１００　…（２５）
           Ｒ＊２＝０．８６
となり、各因子の依存率は、αが３３％、ｄＮ１／２が６７％となった。なお、Ｔに関する重回帰式は、
           Ｉｎ（Ｔ）＝［６．８６×１０－３｛α｝－５．０１×１０－３｛ｄＮ｝－１．３４×１０－２］　…（２６）
           Ｒ＊２＝０．７９
とも近似できたが、Ｒ＊２の大きい式（２５）を以後の計算では用いた。 As a result of the multiple regression analysis by the first structural parameter group N, d, α in the cubic axis pore model, the multiple regression equation for T at λ = 13.5 nm is
T = [6.02 × 10 −3 {α} −8.69 × 10 −3 {dN 1/2 } +1.00] × 100 (25)
R * 2 = 0.86
Thus, the dependency rate of each factor was 33% for α and 67% for dN 1/2 . The multiple regression equation for T is
In (T) = [6.86 × 10 −3 {α} −5.01 × 10 −3 {dN} −1.34 × 10 −2 ] (26)
R * 2 = 0.79
However, equation (25) having a large R * 2 was used in the subsequent calculations.
　また、λ＝１３．５ｎｍでのΔに関する重回帰式は、
           Δ＝［１．９９×１０－３｛ｄＮ１／２｝－１．２５×１０－２］×１００　…（２７）
           Ｒ＊２＝０．７１
となった。なお、Δに関する重回帰式は、ペリクル膜を２回通過する際の散乱率が１回通過する場合の値をほぼ２倍する必要がある等を説明する上では理論的には好ましく、
           Δ＝［９．１４×１０－４｛ｄＮ｝－７．５５×１０－３］×１００　…（２８）
           Ｒ＊２＝０．６６
とも近似できたが、Ｒ＊２の大きい式（２７）を以後の計算では用いた。 Also, the multiple regression equation for Δ at λ = 13.5 nm is
Δ = [1.99 × 10 −3 {dN 1/2 } −1.25 × 10 −2 ] × 100 (27)
R * 2 = 0.71
It became. It should be noted that the multiple regression equation for Δ is theoretically preferable in order to explain that it is necessary to almost double the value when the scattering rate when passing through the pellicle film twice passes,
Δ = [9.14 × 10 −4 {dN} −7.55 × 10 −3 ] × 100 (28)
R * 2 = 0.66
However, Equation (27) having a large R * 2 was used in the subsequent calculations.
　一方、λ＝６．７５ｎｍでのＴに関する重回帰式は、
           Ｔ＝［１．０７×１０－３｛α｝－２．９５×１０－３｛ｄＮ１／２｝＋１．００］×１００　…（２９）
           Ｒ＊２＝０．９１
となり、各因子の依存率は、αが２２％、ｄＮ１／２が７８％となった。なお、Ｔに関する重回帰式は、
           Ｉｎ（Ｔ）＝［１．０６×１０－３｛α｝－１．５１×１０－３｛ｄＮ｝＋２．８４×１０－４］　…（３０）
           Ｒ＊２＝０．９１
とも近似できたが、式（２５）との整合性から式（２９）を以後の計算では用いた。 On the other hand, the multiple regression equation for T at λ = 6.75 nm is
T = [1.07 × 10 −3 {α} −2.95 × 10 −3 {dN 1/2 } +1.00] × 100 (29)
R * 2 = 0.91
Thus, the dependency rate of each factor was 22% for α and 78% for dN 1/2 . The multiple regression equation for T is
In (T) = [1.06 × 10 −3 {α} −1.51 × 10 −3 {dN} + 2.84 × 10 −4 ] (30)
R * 2 = 0.91
Although both could be approximated, Equation (29) was used in the subsequent calculations because of its consistency with Equation (25).
　また、λ＝６．７５ｎｍでのΔに関する重回帰式は、
           Δ＝［９．０６×１０－４｛ｄＮ１／２｝－５．５０×１０－３］×１００　…（３１）
           Ｒ＊２＝０．６３
となった。なお、Δに関する重回帰式は、
           Δ＝［４．３４×１０－４｛ｄＮ｝－３．８５×１０－３］×１００　…（３２）
           Ｒ＊２＝０．６２
とも近似できたが、Ｒ＊２の大きい式（３１）を以後の計算では用いた。 Also, the multiple regression equation for Δ at λ = 6.75 nm is
Δ = [9.06 × 10 −4 {dN 1/2 } −5.50 × 10 −3 ] × 100 (31)
R * 2 = 0.63
It became. The multiple regression equation for Δ is
Δ = [4.34 × 10 −4 {dN} −3.85 × 10 −3 ] × 100 (32)
R * 2 = 0.62
However, Equation (31) having a large R * 2 was used in the subsequent calculations.
　これらの結果より、立方体軸組細孔モデルにおいて、Ｔには、立方体壁組細孔モデルのｄＮに対応して、膜厚方向への実質的な厚みに相当すると考えられるｄＮ１／２という値が大きな影響を与え、細孔の大きさに対応するαは、前者の因子ほど影響は与えないことが分かる。一方、Δには、立方体軸組細孔モデルでは、連結した細孔であり、αが形式的な意味しか持たないため、α＝１とみなされ、ｄＮ１／２の形で影響を与える、すなわち、細孔径の影響がないことを意味している。 From these results, in the cubic axis set pore model, T is a value of dN 1/2 which is considered to correspond to a substantial thickness in the film thickness direction corresponding to dN of the cube wall set pore model. Has a great influence, and it can be seen that α corresponding to the size of the pore does not influence as much as the former factor. On the other hand, Δ is a connected pore in the cubic axis pore model, and since α has only a formal meaning, α is regarded as 1 and has an influence in the form of dN 1/2 . That is, it means that there is no influence of the pore diameter.
＜ステップ１－３＞
　立方体壁組細孔モデル及び立方体軸組細孔モデルにおける、第２構造パラメータ群ρ、Ｄ、αによるＴ、Δへの影響 <Step 1-3>
Influence on T and Δ by the second structural parameter group ρ, D, α in the cubic wall group pore model and the cubic axis group pore model
　続いて、第２構造パラメータ群ρ、Ｄ、αによるＴ、Δへの影響を調べる。立方体壁組細孔モデルにおける、第２構造パラメータ群ρ、Ｄ、αによる重回帰分析の結果、λ＝１３．５ｎｍでのＴに関する重回帰式は、
           Ｔ＝［－１．２６×１０－３｛Ｄρ（λα）１／２｝－９．５２×１０－３｛ρＤ｝＋９．６０×１０－1］×１００　…（３３）
           Ｒ＊２＝０．９８
となり、各因子の依存率は、Ｄρ（λα）１／２が６０％、ρＤが４０％となった。また、λ＝１３．５ｎｍでのΔに関する重回帰式は、
           Δ＝［９．７２×１０－４｛Ｄρ（λα）１／２｝－３．７５×１０－３（ρＤ）＋３．１６×１０－３］×１００　…（３４）
           Ｒ＊２＝０．９３
となり、各因子の依存率は、Ｄρ（λα）１／２が７４％、ρＤが２６％となった。 Subsequently, the influence of the second structural parameter group ρ, D, α on T, Δ is examined. As a result of the multiple regression analysis using the second structural parameter group ρ, D, α in the cubic wall set pore model, the multiple regression equation for T at λ = 13.5 nm is
T = [− 1.26 × 10 −3 {Dρ (λα) 1/2 } −9.52 × 10 −3 {ρD} + 9.60 × 10 −1 ] × 100 (33)
R * 2 = 0.98
Thus, the dependency ratio of each factor was 60% for Dρ (λα) 1/2 and 40% for ρD. Also, the multiple regression equation for Δ at λ = 13.5 nm is
Δ = [9.72 × 10 −4 {Dρ (λα) 1/2 } −3.75 × 10 −3 (ρD) + 3.16 × 10 −3 ] × 100 (34)
R * 2 = 0.93
Thus, the dependency rate of each factor was 74% for Dρ (λα) 1/2 and 26% for ρD.
　一方、λ＝６．７５ｎｍでのＴに関する重回帰式は、
           Ｔ＝［－６．６２×１０－４｛Ｄρ（λα）１／２｝－１．４１×１０－３（ρＤ）＋９．９６×１０－1］×１００　…（３５）
           Ｒ＊２＝０．９９
となり、各因子の依存率は、Ｄρ（λα）１／２が８１％、ρＤが１９％となった。 On the other hand, the multiple regression equation for T at λ = 6.75 nm is
T = [− 6.62 × 10 −4 {Dρ (λα) 1/2 } −1.41 × 10 −3 (ρD) + 9.96 × 10 −1 ] × 100 (35)
R * 2 = 0.99
Thus, the dependency ratio of each factor was 81% for Dρ (λα) 1/2 and 19% for ρD.
　また、λ＝６．７５ｎｍでのΔに関する重回帰式は、
           Δ＝［４．４９×１０－４｛Ｄρ（λα）１／２｝－１．１１×１０－３｛ρＤ｝－１．８４×１０－３］×１００　…（３６）
           Ｒ＊２＝０．９５
となり、各因子の依存率は、Ｄρ（λα）１／２が７８％、ρＤが２２％となった。 Also, the multiple regression equation for Δ at λ = 6.75 nm is
Δ = [4.49 × 10 −4 {Dρ (λα) 1/2 } −1.11 × 10 −3 {ρD} −1.84 × 10 −3 ] × 100 (36)
R * 2 = 0.95
Thus, the dependency rate of each factor was 78% for Dρ (λα) 1/2 and 22% for ρD.
　一方、立方体軸組細孔モデルにおける、第２構造パラメータ群ρ、Ｄ、αによる重回帰分析の結果、λ＝１３．５ｎｍでのＴに関する重回帰式は、
           Ｔ＝［－１．５９×１０－４｛Ｄρ（λα）１／２｝－１．５９×１０－３｛ρＤ｝＋９．６６×１０－１］×１００　…（３７）
           Ｒ＊２＝０．９９
となり、各因子の依存率は、Ｄρ（λα）１／２が３５％、ρＤが６５％となった。 On the other hand, as a result of the multiple regression analysis using the second structural parameter groups ρ, D, and α in the cubic frame pore model, the multiple regression equation for T at λ = 13.5 nm is
T = [− 1.59 × 10 −4 {Dρ (λα) 1/2 } −1.59 × 10 −3 {ρD} + 9.66 × 10 −1 ] × 100 (37)
R * 2 = 0.99
Thus, the dependency ratio of each factor was 35% for Dρ (λα) 1/2 and 65% for ρD.
　また、λ＝１３．５ｎｍでのΔに関する重回帰式は、
           Δ＝［１．５９×１０－４｛Ｄρ（λα）１／２｝－３．５７×１０－４（ρＤ）－２．４１×１０－３］×１００　…（３８）
           Ｒ＊２＝０．９１
となり、各因子の依存率は、Ｄρ（λα）１／２が７０％、ρＤが３０％となった。 Also, the multiple regression equation for Δ at λ = 13.5 nm is
Δ = [1.59 × 10 −4 {Dρ (λα) 1/2 } −3.57 × 10 −4 (ρD) −2.41 × 10 −3 ] × 100 (38)
R * 2 = 0.91
Thus, the dependency ratio of each factor was 70% for Dρ (λα) 1/2 and 30% for ρD.
　一方、λ＝６．７５ｎｍでのＴに関する重回帰式は、
           Ｔ＝［－８．２０×１０－５｛Ｄρ（λα）１／２｝－３．２７×１０－４（ρＤ）＋１．００］×１００　…（３９）
           Ｒ＊２＝０．９９
となり、各因子の依存率は、Ｄρ（λα）１／２が５４％、ρＤが４６％となった。 On the other hand, the multiple regression equation for T at λ = 6.75 nm is
T = [− 8.20 × 10 −5 {Dρ (λα) 1/2 } −3.27 × 10 −4 (ρD) +1.00] × 100 (39)
R * 2 = 0.99
Thus, the dependency rate of each factor was 54% for Dρ (λα) 1/2 and 46% for ρD.
　また、λ＝６．７５ｎｍでのΔに関する重回帰式は、
           Δ＝［７．６０×１０－５｛Ｄρ（λα）１／２｝－１．６６×１０－４｛ρＤ｝－１．３１×１０－３］×１００　…（４０）
           Ｒ＊２＝０．９３
となり、各因子の依存率は、Ｄρ（λα）１／２が６８％、ρＤが３２％となった。 Also, the multiple regression equation for Δ at λ = 6.75 nm is
Δ = [7.60 × 10 −5 {Dρ (λα) 1/2 } −1.66 × 10 −4 {ρD} −1.31 × 10 −3 ] × 100 (40)
R * 2 = 0.93
Thus, the dependency rate of each factor was 68% for Dρ (λα) 1/2 and 32% for ρD.
　これらの結果では、Ｔ、Δの説明変数｛Ｄρ（λα）１／２｝、｛ρＤ｝には共通因子として見かけ密度ρと膜厚Ｄとの積ρＤが含まれた形で大きなＲ＊２が得られていることより、Ｔ、Δ共にρＤが大きな影響を与えることが分かる。ρＤは、膜厚方向への単位面積あたりの膜重量に相当することから、膜厚方向の実質的な物質の量に関係しており、ρが大きければＤを薄くする必要があるが、ρが小さければ、Ｄを大きくできることが分かる。 In these results, the explanatory variables {Dρ (λα) 1/2 } and {ρD} of T and Δ have a large R * 2 in the form that the product ρD of the apparent density ρ and the film thickness D is included as a common factor. Is obtained, it can be seen that ρD has a great influence on both T and Δ. Since ρD corresponds to the film weight per unit area in the film thickness direction, it is related to the substantial amount of substance in the film thickness direction, and if ρ is large, D needs to be thinned. If is small, it can be seen that D can be increased.
（２）ステップ２
　ステップ１に示した重回帰式より、定性的には、各構造パラメータ群のＴ、Δへの影響を知ることができた。ステップ１では計算の都合上Ｎ≦５としたが、各基準値（Ｔｉ、Δｉ、Ｄｉ；ｉ＝１～３）を満足する第１構造パラメータ群（Ｎ、ｄ、α）及び第２構造パラメータ群（ρ、Ｄ、α）の値を知るため、各α、ｄにおけるＴｉ及びΔｉの各基準値を満足するＮの値、Ｎ（Ｔｉ）、Ｎ（Δｉ）を推定し、更に式（２）を用いてＴ及びΔの各基準値を満足するＤの値Ｄ（Ｔｉ）、Ｄ（Δｉ）を求めた。ただし、Δｉに関しては、式（２７）及び式（３１）のＲ＊２が多少小さいため、Ｔｉに比べて誤差が大きくなることが予想された。そこで、Δｉに関しては定義による散乱量の値の１／２を各Δｉの上限値とした（例えば、定義によれば散乱量１０％をΔ１とするべきだが、５％をΔ１の上限とした）。この結果、ペリクル膜を２回通過したときの散乱量がΔ１、Δ２、Δ３に対応して、それぞれ１０％、５％、１％となった。なお、Ｎ（Ｔｉ）、Ｎ（Δｉ）及びＤ（Ｔｉ）、Ｄ（Δｉ）は、それぞれＴ及びΔの各基準値を満足する、上限の積層数Ｎｍａｘ、上限の膜厚Ｄｍａｘを意味する。 (2) Step 2
From the multiple regression equation shown in Step 1, qualitatively, it was possible to know the influence of each structural parameter group on T and Δ. In step 1, N ≦ 5 for the sake of calculation, but the first structural parameter group (N, d, α) and the second structural parameter satisfying the respective reference values (Ti, Δi, Di; i = 1 to 3). In order to know the values of the group (ρ, D, α), the values of N satisfying the reference values of Ti and Δi at each α, d, N (Ti), N (Δi) are estimated, and further the formula (2 ) To obtain D values D (Ti) and D (Δi) that satisfy the respective reference values of T and Δ. However, with respect to Δi, since R * 2 in Equation (27) and Equation (31) is somewhat smaller, it was expected that the error would be larger than Ti. Therefore, for Δi, ½ of the value of the scattering amount by definition is set as the upper limit value of each Δi (for example, according to the definition, 10% of the scattering amount should be Δ1, but 5% is the upper limit of Δ1). . As a result, the amount of scattering when passing through the pellicle film twice was 10%, 5%, and 1%, corresponding to Δ1, Δ2, and Δ3, respectively. N (Ti), N (Δi), D (Ti), and D (Δi) mean the upper limit number of layers N max and the upper limit film thickness D max that satisfy the reference values of T and Δ, respectively. To do.
　ステップ２より、第１構造パラメータα、ｄのもとで、Ｔ及びΔの各基準値を満足する上限の積層数Ｎｍａｘ、第２構造パラメータα、ρのもとで、Ｔ及びΔの各基準値を満足する上限の膜厚Ｄｍａｘを、すなわちＤの範囲を定量的に知ることができる。 From Step 2, under the first structural parameters α and d, the upper limit number of layers N max satisfying the respective reference values of T and Δ, and under the second structural parameters α and ρ, each of T and Δ It is possible to quantitatively know the upper limit film thickness Dmax that satisfies the reference value, that is, the range of D.
　この結果、ρに関しては、ρが小さくなるほど、Ｔ及びΔの各基準値を満足する上限の膜厚Ｄｍａｘは増大する傾向があった（特に、Ｔに関しては指数関数的に増大する）。一方、αに関しては、ρの値に対してＤｍａｘの値が大きく変動するため、ρに関する傾向ほど明確には言えないが、Ｔに対してはαが大きくなるほどＤｍａｘは増大し、Δに対してはαが大きくなるほどＤｍａｘは減少する傾向があった。 As a result, with respect to ρ, as ρ becomes smaller, the upper limit film thickness Dmax that satisfies the respective reference values of T and Δ tended to increase (particularly, T increases exponentially). On the other hand, with respect to α, since the value of D max varies greatly with respect to the value of ρ, it cannot be said as clearly as the tendency with respect to ρ. However, with respect to T, D max increases as α increases, and Δ On the other hand, D max tended to decrease as α increased.
（３）ステップ３
　ステップ２から、各基準値Ｔｉ、Δｉ、Ｄｉ（ｉ＝１～３）を満足するために必要な構造パラメータα、Ｎ、ｄ、ρ、Ｄの範囲を求めることができる。しかし、本実施形態では、上記に加えて、現実的に得られる炭素多孔膜としての制約条件１～制約条件４を満足した構造パラメータα、Ｎ、ｄ、ρ、Ｄの範囲を本実施形態の課題を満足する炭素多孔膜とする。
・制約条件１：　０．３３５ｎｍ≦ｄ　…（４１）
・制約条件２：　１≦Ｎ　…（４２）
・制約条件３：　０．５≦α　…（４３）
・制約条件４：　１．０×１０－３ｇ／ｃｍ３≦ρ≦２．２５ｇ／ｃｍ３　…（４４） (3) Step 3
From step 2, the ranges of the structural parameters α, N, d, ρ, D required to satisfy the respective reference values Ti, Δi, Di (i = 1 to 3) can be obtained. However, in the present embodiment, in addition to the above, the ranges of the structural parameters α, N, d, ρ, and D satisfying the constraint conditions 1 to 4 as a carbon porous membrane that can be actually obtained are set in the present embodiment. A porous carbon membrane satisfying the problems is obtained.
Restriction 1: 0.335 nm ≦ d (41)
Restriction condition 2: 1 ≦ N (42)
Restriction condition 3: 0.5 ≦ α (43)
Restriction condition 4: 1.0 × 10 −3 g / cm 3 ≦ ρ ≦ 2.25 g / cm 3 (44)
　制約条件１及び制約条件２は、ｄ及びＮに関する定義においても説明したミクロ構造パラメータに関するもので、計算の前提となるものであった。なお、ｄに関しては、好ましくは１．３５ｎｍ以上である。またＮに関しては、好ましくは２以上であり、数値が大きければ、各細孔構造モデルにおいて異なるミクロ構造パラメータを有する立方体殻状又は立方体枠状の細孔が、各基準値を満足する範囲内で膜厚方向への積層した膜構造を考えることができる。 Constraint conditions 1 and 2 are related to the microstructure parameters described in the definition of d and N, and are the premise of the calculation. Note that d is preferably 1.35 nm or more. N is preferably 2 or more, and if the value is large, the cubic shell-like or cubic frame-like pores having different microstructure parameters in each pore structure model are within the range satisfying each reference value. A laminated film structure in the film thickness direction can be considered.
　制約条件３は、ミクロ及びマクロに共通な構造パラメータであり、ここで言うα値は、細孔分布のＬ（ｐｅａｋ）に対応した値を示す。本実施形態の意義から、その下限を０．５とする。現実に得られる炭素多孔膜にはα値より小さな細孔径の細孔が含まれ、それらを排除することは困難である。しかし、小さな細孔径の細孔は、炭素多孔膜の膜厚の向上にほとんど貢献せず、その壁厚の積層により透過率を下げるだけであり好ましくない。したがって、細孔分布はＬ（ｐｅａｋ）に集中したシャープな形状のものが好ましい。αの上限は、ステップ２より求められるが、経験的にＬ（ｍａｘ）≒１．５×Ｌ（ｐｅａｋ）～３×Ｌ（ｐｅａｋ）であり、炭素多孔膜中の平均的な細孔径に対応したαの上限値［Ｌ（ｐｅａｋ）／λ］をステップ２から得られるαの上限の１／１．５～１／３としておけば、現実に得られる炭素多孔膜中の最大の細孔径はステップ２から得られるαの上限以下に抑えることができると考えられ好ましい。 Constraint condition 3 is a structural parameter common to both micro and macro, and the α value here indicates a value corresponding to L (peak) of the pore distribution. From the significance of this embodiment, the lower limit is set to 0.5. The carbon porous membrane actually obtained contains pores having pore diameters smaller than the α value, and it is difficult to eliminate them. However, pores with small pore diameters are not preferable because they hardly contribute to the improvement of the film thickness of the carbon porous membrane, and only reduce the transmittance due to the lamination of the wall thickness. Therefore, it is preferable that the pore distribution has a sharp shape centered on L (peak). The upper limit of α is obtained from step 2, but empirically L (max) ≈1.5 × L (peak) to 3 × L (peak), corresponding to the average pore diameter in the carbon porous membrane If the upper limit [L (peak) / λ] of α is set to 1 / 1.5 to 1/3 of the upper limit of α obtained from step 2, the maximum pore diameter in the carbon porous membrane actually obtained is It is considered that it can be suppressed to the upper limit of α obtained from Step 2, and is preferable.
　制約条件４は、炭素エアロゲルとして現実に得られている見かけ密度ρの下限値から定めたものである。ρとαλ／ｄの逆数は、立方体壁組細孔モデルでは式（５）と、立方体軸組細孔モデルでは式（８）と関連している。αλ／ｄはその項の構成より、個々の細孔自体の強度の指標となるものである。具体的には、その値が小さければ（ρが大きければ）、細孔自体は強固なものとなる。 Constraint condition 4 is determined from the lower limit of the apparent density ρ actually obtained as carbon aerogel. The reciprocals of ρ and αλ / d are related to the equation (5) in the cubic wall set pore model and the equation (8) in the cube axis set pore model. αλ / d is an index of the strength of the individual pores by the structure of the term. Specifically, if the value is small (ρ is large), the pores themselves are strong.
　現実的に得られる炭素多孔膜としての制約条件１～制約条件４のもと、ステップ２から、各基準値Ｔｉ、Δｉ、Ｄｉ（ｉ＝１～３）を満足するために必要な構造パラメータＤ、ρ、α、ｄの範囲は、以下のように求められた。 The structural parameter D necessary for satisfying the respective reference values Ti, Δi, Di (i = 1 to 3) from step 2 under the constraint conditions 1 to 4 as the carbon porous membrane that can be obtained in practice. , Ρ, α, d were determined as follows.
　膜厚Ｄの範囲は、立方体軸組細孔モデルでは、λ＝１３．５ｎｍにおいてはＤ＝１００ｎｍ～２３８８１ｎｍ（２３μｍ）、λ＝６．７５ｎｍにおいてはＤ＝１００ｎｍ～６３８５０ｎｍ（６３μｍ）であった。立方体壁組細孔モデルでは、λ＝１３．５ｎｍにおいてはＤ＝１００ｎｍ～５１７ｎｍ、λ＝６．７５ｎｍにおいてはＤ＝１００ｎｍ～１７１１ｎｍであり、Ｄの上限値はそれぞれの細孔構造モデルにおいて最小のρ、最大のαλ／ｄで実現した。 In the cubic axis pore model, the range of the film thickness D was D = 100 nm to 23881 nm (23 μm) at λ = 13.5 nm, and D = 100 nm to 63850 nm (63 μm) at λ = 6.75 nm. In the cubic wall set pore model, D = 100 nm to 517 nm at λ = 13.5 nm, D = 100 nm to 1711 nm at λ = 6.75 nm, and the upper limit value of D is the smallest in each pore structure model It was realized with ρ and the maximum αλ / d.
　見かけ密度ρの範囲は、立方体軸組細孔モデルでは、λ＝１３．５ｎｍにおいてはρ＝１．０×１０－３～９．４×１０－１ｇ／ｃｍ３、λ＝６．７５ｎｍにおいてはρ＝１．２×１０－３～２．１ｇ／ｃｍ３であった。立方体壁組細孔モデルでは、λ＝１３．５ｎｍにおいてはρ＝８．２×１０－２～５．６×１０－１ｇ／ｃｍ３、λ＝６．７５ｎｍにおいてはρ＝８．８×１０－２～１．７ｇ／ｃｍ３であった。一方、個々の細孔自体の強度の指標となるαλ／ｄの範囲は、ρの上限値はそれぞれの細孔構造モデル及び対応するλにおいての最小のαλ／ｄに、ρの下限値は最大のαλ／ｄに対応した。すなわち、上記のρの範囲に対応する形でαλ／ｄの範囲を表記すると、立方体軸組細孔モデルでは、λ＝１３．５ｎｍにおいてはαλ／ｄ＝８１～１．２５、λ＝６．７５ｎｍにおいてはαλ／ｄ＝７５～０．１６であった。立方体壁組細孔モデルでは、λ＝１３．５ｎｍにおいてはαλ／ｄ＝８１～１０、λ＝６．７５ｎｍにおいてはαλ／ｄ＝７５～１．７であった。 The range of the apparent density ρ is ρ = 1.0 × 10 −3 to 9.4 × 10 −1 g / cm 3 at λ = 13.5 nm and λ = 6.75 nm in the cubic axial pore model. Was ρ = 1.2 × 10 −3 to 2.1 g / cm 3 . In the cubic wall set pore model, ρ = 18.2 × 10 −2 to 5.6 × 10 −1 g / cm 3 at λ = 13.5 nm, and ρ = 8.8 × at λ = 6.75 nm. 10 −2 to 1.7 g / cm 3 . On the other hand, the range of αλ / d serving as an index of the strength of individual pores is such that the upper limit of ρ is the minimum αλ / d in each pore structure model and the corresponding λ, and the lower limit of ρ is the maximum Of αλ / d. That is, when the range of αλ / d is expressed in a form corresponding to the above range of ρ, αλ / d = 81 to 1.25 at λ = 13.5 nm and λ = 6. At 75 nm, αλ / d = 75 to 0.16. In the cubic wall set pore model, αλ / d = 81 to 10 at λ = 13.5 nm, and αλ / d = 75 to 1.7 at λ = 6.75 nm.
　細孔サイズパラメータαの範囲は、立方体軸組細孔モデルでは、λ＝１３．５ｎｍにおいてはα＝０．５～１８１、λ＝６．７５ｎｍにおいてはα＝０．５～７２６である。立方体壁組細孔モデルでは、０．３３５ｎｍ≦ｄのもとでは、λ＝１３．５ｎｍにおいてはα＝０．５～２０、λ＝６．７５ｎｍにおいてはα＝０．５～８６であった。また、１．３５ｎｍ≦ｄのもとでは、λ＝１３．５ｎｍにおいてはα＝０．５～１８、λ＝６．７５ｎｍにおいてはα＝０．５～８４であった。 The range of the pore size parameter α is α = 0.5 to 181 at λ = 13.5 nm and α = 0.5 to 726 at λ = 6.75 nm in the cubic axis pore model. In the cubic wall set pore model, α = 0.5 to 20 at λ = 13.5 nm and α = 0.5 to 86 at λ = 6.75 nm under 0.335 nm ≦ d. . Under 1.35 nm ≦ d, α = 0.5 to 18 at λ = 13.5 nm, and α = 0.5 to 84 at λ = 6.75 nm.
　細孔の壁厚又は柱太さｄの範囲は、立方体軸組細孔モデルでは、λ＝１３．５ｎｍにおいてはｄ＝０．３３５ｎｍ～３０．５ｎｍ、λ＝６．７５ｎｍにおいてはｄ＝０．３３５ｎｍ～６０．６ｎｍである。立方体壁組細孔モデルでは、λ＝１３．５ｎｍにおいてはｄ＝０．３３５ｎｍ～６．７４ｎｍ、λ＝６．７５ｎｍにおいてはα＝０．３３５ｎｍ～３２．２ｎｍであった。 The range of the pore wall thickness or the column thickness d is, in the cubic axis pore model, d = 0.335 nm to 30.5 nm at λ = 13.5 nm and d = 0.0.3 nm at λ = 6.75 nm. 335 to 60.6 nm. In the cubic wall set pore model, d = 0.335 nm to 6.74 nm at λ = 13.5 nm, and α = 0.335 nm to 32.2 nm at λ = 6.75 nm.
　以下、ステップ３において、ペリクル膜として好ましい特徴的構造（但し、ｄ≧１．３５ｎｍとする場合）の例を示す。なお、構造パラメータ群及び制約条件の値の各範囲を｛α、ｄ［単位ｎｍ］、Ｄ［単位ｎｍ］、ρ［単位ｇ／ｃｍ３］、αλ／ｄ｝の形で各細孔構造モデル、ＥＵＶ光の波長毎にその構造の例を表記する。なお、｛Ａ１、Ｂ１、Ｃ１１－Ｃ１２、Ｄ１、Ｅ１｝－｛Ａ２、Ｂ１、Ｃ２１－Ｃ２２、Ｄ２、Ｅ２｝は、壁厚又は柱太さｄが同Ｂ１値のもと、細孔サイズパラメータαがＡ１からＡ２の範囲をそれぞれのαに対応して膜厚ＤがＣ１１－Ｃ２２、Ｃ２１－Ｃ２２の範囲で本実施形態の基準値を取り得ることを意味するものとする。 Hereinafter, in Step 3, an example of a characteristic structure preferable as a pellicle film (provided that d ≧ 1.35 nm) is shown. In addition, each pore structure model is represented in the form of {α, d [unit nm], D [unit nm], ρ [unit g / cm 3 ], αλ / d} in the ranges of the structural parameter group and the constraint condition values. An example of the structure is described for each wavelength of EUV light. Note that {A1, B1, C11-C12, D1, E1}-{A2, B1, C21-C22, D2, E2} are the pore size parameters with the wall thickness or the column thickness d being the same B1 value. It means that the reference value of the present embodiment can be taken when α is in the range of A1 to A2 and the film thickness D is in the range of C11-C22 and C21-C22 corresponding to each α.
＜ステップ３－１＞
　ペリクル膜として理想的な構造－Ｔ３・δ３・Ｄ３ <Step 3-1>
Ideal structure for pellicle film-T3 ・ δ3 ・ D3
　特徴的構造１は、ペリクル膜として理想的な構造である。立方体軸組細孔モデルのλ＝１３．５ｎｍにおいては、
｛α、ｄ、Ｄ、ρ、αλ／ｄ｝＝｛２、１．３５、５００－８３５、１．５×１０－２、２０｝－｛８、１．３５、５００－４６５９、１．０×１０－３、８０｝、｛３、２．０１、５００－６７７、１．５×１０－２、２０｝－｛１０、２．０１、５００－２６３５、１．４×１０－３、６７｝、｛４、２．７、５００－５９２、１．５×１０－２、２０｝－｛１５、２．７０、５００－２１８８、１．６×１０－３、７５｝、｛６、３．３５、５００－５８７、１．０×１０－２、２４｝－｛２０、３．３５、５００－１８９４、１．０×１０－３、８１｝、｛８、４．０２、５００－５４２、８．５×１０－３、２７｝－｛２０、４．０２、５００－１３２０、１．４×１０－３、６７｝、｛１５、４．６９、５００－７３６、３．４×１０－３、４３｝－｛２５、４．６９、５００－１２１２、１．３×１０－３、７２｝、｛１５、５．４０、５００－５５９、４．５×１０－３、３８｝－｛３０、５．４０、５００－１０９８、１．２×１０－３、７５｝
の構造パラメータを有する炭素多孔膜である。 The characteristic structure 1 is an ideal structure as a pellicle film. At λ = 13.5 nm in the cubic axis pore model,
{Α, d, D, ρ, αλ / d} = { 2 , 1.35, 500-835, 1.5 × 10 −2 , 20} − {8, 1.35, 500-4659, 1.0 × 10 −3 , 80}, { 3 , 2.01, 500-677, 1.5 × 10 −2 , 20}-{10, 2.01, 500-2635, 1.4 × 10 −3 , 67 }, {4, 2.7, 500-592, 1.5 × 10 −2 , 20}-{15, 2.70, 500-2188, 1.6 × 10 −3 , 75}, {6, 3 .35, 500-587, 1.0 × 10 −2 , 24}-{20, 3.35, 500-1894, 1.0 × 10 −3 , 81}, {8, 4.02, 500-542 , 8.5 × 10 -3, 27} - {20,4.02,500-1320,1.4 × 10 -3, 67}, {15,4.69,500-736,3 4 × 10 -3, 43} - {25,4.69,500-1212,1.3 × 10 -3, 72}, {15,5.40,500-559,4.5 × 10 -3, 38}-{30, 5.40, 500-1098, 1.2 × 10 −3 , 75}
A porous carbon membrane having the following structural parameters.
　これらの構造パラメータを有する炭素多孔膜は、Ｔ＝Ｔ３、Δ＝Δ３、Ｄ＝Ｄ３の物性値を得ることができることから、ペリクル膜として最も適した構造である。特に、
｛２、１．３５、５００－８３５、１．５×１０－２、２０｝、｛３、２．０１、５００－６７７、１．５×１０－２、２０｝、｛４、２．７、５００－５９２、１．５×１０－２、２０｝、｛６、３．３５、５００－５８７、１．０×１０－２、２４｝
の構造パラメータを有する炭素多孔膜は、ρ≧１．０×１０－２ｇ／ｃｍ３であり、膜強度の観点から更に好ましい。 A carbon porous membrane having these structural parameters is the most suitable structure as a pellicle membrane because it can obtain physical property values of T = T3, Δ = Δ3, and D = D3. In particular,
{ 2 , 1.35, 500-835, 1.5 × 10 −2 , 20}, {3, 2.01, 500-677, 1.5 × 10 −2 , 20}, {4, 2.7 , 500-592, 1.5 × 10 −2 , 20}, {6, 3.35, 500-587, 1.0 × 10 −2 , 24}
A carbon porous membrane having the following structural parameters satisfies ρ ≧ 1.0 × 10 −2 g / cm 3 , and is more preferable from the viewpoint of membrane strength.
　立方体壁組細孔モデルでは、λ＝１３．５ｎｍ及び６．７５ｎｍにおいては、Ｔ＝Ｔ３、Δ＝Δ３、Ｄ＝Ｄ３の物性値を得る構造パラメータを有する炭素多孔膜は存在しない。 In the cubic wall set pore model, there are no carbon porous membranes having structural parameters for obtaining physical properties of T = T3, Δ = Δ3, and D = D3 at λ = 13.5 nm and 6.75 nm.
＜ステップ３－２＞
　立方体壁組細孔モデルでの透過率優先の構造－Ｔ２・δ２・Ｄ１ <Step 3-2>
Structure with priority on transmittance in the cubic wall-set pore model-T2, δ2, D1
　特徴的構造２として、立方体壁組細孔モデルのλ＝１３．５ｎｍでは、高透過率優先の構造として、Ｔ＝Ｔ２、Δ＝Δ２、Ｄ＝Ｄ１の物性値を得る構造パラメータを有する炭素多孔膜が存在する。すなわち、
｛α、ｄ、Ｄ、ρ、αλ／ｄ｝＝｛２、１．３５、１００－１１９、３．１×１０－１、２０｝－｛８、１．３５、１１１－２１０、８．２×１０－２、８０｝、｛３、２．０１、１００－１１０、３．０×１０－１、２０｝－｛８、２．０１、１１２－１４３、１．２×１０－１、５４｝、｛６、２．７０、１００－１１４、２．１×１０－１、３０｝
の構造パラメータを有する炭素多孔膜であり、ρ≧１．０×１０－２ｇ／ｃｍ３であり、膜強度の観点から好ましい。 As characteristic structure 2, at λ = 13.5 nm of the cubic wall set pore model, a carbon porous material having a structural parameter for obtaining physical property values of T = T2, Δ = Δ2, and D = D1 as a structure with high transmittance priority. A membrane is present. That is,
{Α, d, D, ρ, αλ / d} = {2, 1.35, 100-119, 3.1 × 10 −1 , 20} − {8, 1.35, 111-210, 8.2 × 10 −2 , 80}, {3, 2.01, 100-110, 3.0 × 10 −1 , 20}-{8, 2.01, 112-143, 1.2 × 10 −1 , 54 }, {6, 2.70, 100-114, 2.1 × 10 −1 , 30}
A porous carbon film having the following structural parameters, ρ ≧ 1.0 × 10 −2 g / cm 3, which is preferable from the viewpoint of film strength.
＜ステップ３－３＞
　膜厚優先の構造－Ｔ１・Δ１・Ｄ３ <Step 3-3>
Thickness priority structure-T1, Δ1, D3
　特徴的構造３として、膜厚優先の構造、すなわちＴ＝Ｔ１、Δ＝Δ１、Ｄ＝Ｄ３の物性値を得る構造パラメータを有する炭素多孔膜が存在する。立方体軸組細孔モデルのλ＝１３．５ｎｍでは、
｛α、ｄ、Ｄ、ρ、αλ／ｄ｝＝｛０．５、１．３５、１５８８－１６３６、１．７×１０－１、５｝－｛８、１．３５、２１４０２－３５６５０、１．０×１０－３、８０｝、｛０．５、２．０１、７７６－７９９、３．０×１０－１、３．４｝－｛１０、２．０１、１２３８８－２２５０８、１．４×１０－３、６７｝、｛１、２．７０、７９６－８５０、１．７×１０－１、５｝－｛１５、２．７０、１４３５０－２４０４７、１．２×１０－３、７５｝、｛１、３．３５、５４０－５７８、２．３、４｝－｛２０、３．３５、１６５２３－２４１４０、１．０×１０－３、８１｝、｛２、４．０２、６９０－７８９、１．０×１０－１、６７｝－｛２０、４．０２、１１５０４－１６８０６、１．４×１０－３、６７｝、｛２、４．６９、５２０－５９４、１．３×１０－１、５．８｝－｛２５、４．６９、１３５５１－１５４２０、１．３×１０－３、７２｝、｛３、５．４０、５６８－６９４、８．６×１０－２、７．５｝－｛２５、５．４０、１０２４５－１１６５８、１．７×１０－３、６３｝、｛６、８．１、５００－７２６、５．２×１０－２、１０｝－｛２５、８．１、４５９５－５２２８、３．７×１０－３、４２｝、｛８、１０．８、５００－６１８、５．２×１０－２、１０｝－｛２５、１０．８、２６１２－２９７０、６．４×１０－３、３１｝、｛１０、１３．５、５００－５５４、５．２×１０－２、１０｝－｛２５、１３．５、１６９１－１９２２、９．７×１０－３、２５｝、｛１５、１６．２、５００－７２８、３．５×１０－２、１３｝－｛２５、１６．２、１１９１－１３５２、１．４×１０－２、２１｝、｛２０、２１．６、５００－６４１、３．５×１０－２、１２．５｝－｛２５、２１．６、６９３－７８４、２．３×１０－２、１５．６｝
の構造パラメータを有する炭素多孔膜である。 As the characteristic structure 3, there is a porous film having a structure parameter that obtains physical properties of T = T1, Δ = Δ1, and D = D3. At λ = 13.5 nm of the cubic axis pore model,
{Α, d, D, ρ, αλ / d} = {0.5, 1.35, 1588-1636, 1.7 × 10 −1 , 5}-{8, 1.35, 21402-35650, 1 0.0 × 10 −3 , 80}, {0.5, 2.01, 776-799, 3.0 × 10 −1 , 3.4}-{10, 2.01, 12388-22508, 1.4 × 10 −3 , 67}, { 1 , 2.70, 796-850, 1.7 × 10 −1 , 5}-{15, 2.70, 14350-24047, 1.2 × 10 −3 , 75 }, {1, 3.35, 540-578, 2.3, 4}-{20, 3.35, 16523-24140, 1.0 × 10 −3 , 81}, {2, 4.02, 690 -789,1.0 × 10 -1, 67} - {20,4.02,11504-16806,1.4 × 10 -3, 67}, {2, .69,520-594,1.3 × 10 -1, 5.8} - {25,4.69,13551-15420,1.3 × 10 -3, 72}, {3,5.40,568 -694, 8.6 × 10 −2 , 7.5}-{25, 5.40, 10245-11658, 1.7 × 10 −3 , 63}, {6, 8.1, 500-726, 5 .2 × 10 −2 , 10}-{25, 8.1, 4595-5228, 3.7 × 10 −3 , 42}, {8, 10.8, 500-618, 5.2 × 10 −2 10}-{25, 10.8, 2612-2970, 6.4 × 10 −3 , 31}, {10, 13.5, 500-554, 5.2 × 10 −2 , 10}-{25 , 13.5,1691-1922,9.7 × 10 -3, 25} , {15,16.2,500-728,3.5 × 10 2, 13} - {25,16.2,1191-1352,1.4 × 10 -2, 21}, {20,21.6,500-641,3.5 × 10 -2, 12.5} − {25, 21.6, 693-784, 2.3 × 10 −2 , 15.6}
A porous carbon membrane having the following structural parameters.
　特に、
｛α、ｄ、Ｄ、ρ、αλ／ｄ｝＝｛０．５、１．３５、１５８８－１６３６、１．７×１０－１、５｝－｛２、１．３５、５５５０－６３５９、１．５×１０－２、２０｝、｛０．５、２．０１、７７６－７９９、３．０×１０－１、３．４｝－｛２、２．０１、２５６４－２９３７、３．１×１０－２、１３｝、｛１、２．７０、７９６－８５０、１．７×１０－１、５｝－｛４、２．７０、２７７８－３６３２、１．９×１０－２、２０｝、｛１、３．３５、５４０－５７８、２．３、４｝－｛６、３．３５、２６８５－３９７６、１．０×１０－２、２４｝、｛２、４．０２、６９０－７８９、１．０×１０－１、６７｝－｛６、４．０２、１８８１－２７８４、１．５×１０－３、２０｝、｛２、４．６９、５２０－５９４、１．３×１０－１、５．８｝－｛８、４．６９、１８３３－３０４９、１．１×１０－２、２３｝、｛３、５．４０、５６８－６９４、８．６×１０－２、７．５｝－｛８、５．４０、１３９３－２３１６、１．５×１０－２、２０｝、｛６、８．１、５００－７２６、５．２×１０－２、１０｝－｛１０、８．１、８０６－１４５６、２．１×１０－２、８．１｝、｛８、１０．８、５００－６１８、５．２×１０－２、１０｝－｛１５、１０．８、９４４－１５７３、１．７×１０－２、１９｝、｛１０、１３．５、５００－５５４、５．２×１０－２、１０｝－｛２０、１３．５、１０６９－１５５５、１．５×１０－２、２０｝、｛１５、１６．２、５００－７２８、３．５×１０－２、１３｝－｛２５、１６．２、１１９１－１３５２、１．４×１０－２、２１｝、｛２０、２１．６、５００－６４１、３．５×１０－２、１２．５｝－｛２５、２１．６、６９３－７８４、２．３×１０－２、１５．６｝
の構造パラメータを有する炭素多孔膜は、ρ≧１．０×１０－２ｇ／ｃｍ３であり、膜強度の観点から更に好ましい。 In particular,
{Α, d, D, ρ, αλ / d} = {0.5, 1.35, 1588-1636, 1.7 × 10 −1 , 5}-{2, 1.35, 5550-6359, 1 .5 × 10 −2 , 20}, {0.5, 2.01, 776-799, 3.0 × 10 −1 , 3.4}-{2, 2.01, 2564-2937, 3.1 × 10 −2 , 13}, { 1 , 2.70, 796-850, 1.7 × 10 −1 , 5}-{4, 2.70, 2778-3632, 1.9 × 10 −2 , 20 }, {1, 3.35, 540-578, 2.3, 4}-{6, 3.35, 2687-3976, 1.0 × 10 −2 , 24}, { 2 , 4.02, 690 -789,1.0 × 10 -1, 67} - {6,4.02,1881-2784,1.5 × 10 -3, 20}, {2,4.69,520-594,1 3 × 10 -1, 5.8} - {8,4.69,1833-3049,1.1 × 10 -2, 23}, {3,5.40,568-694,8.6 × 10 - 2 , 7.5}-{8, 5.40, 1393-2316, 1.5 × 10 −2 , 20}, {6, 8.1, 500-726, 5.2 × 10 −2 , 10} -{10, 8.1, 806-1456, 2.1 × 10 −2 , 8.1}, {8, 10.8, 500-618, 5.2 × 10 −2 , 10}-{15, 10.8, 944-1573, 1.7 × 10 −2 , 19}, {10, 13.5, 500-554, 5.2 × 10 −2 , 10}-{20, 13.5, 1069− 1555,1.5 × 10 -2, 20}, {15,16.2,500-728,3.5 × 10 -2, 13} - {25,16.2,1191- 352,1.4 × 10 -2, 21}, {20,21.6,500-641,3.5 × 10 -2, 12.5} - {25,21.6,693-784,2. 3 × 10 −2 , 15.6}
A carbon porous membrane having the following structural parameters satisfies ρ ≧ 1.0 × 10 −2 g / cm 3 , and is more preferable from the viewpoint of membrane strength.
　立方体壁組細孔モデルのλ＝１３．５ｎｍでは、
｛α、ｄ、Ｄ、ρ、αλ／ｄ｝＝｛８、１．３５、５００－５１７、８．２×１０－２、８０｝
の構造パラメータを有する炭素多孔膜である。 At λ = 13.5 nm of the cubic wall set pore model,
{Α, d, D, ρ, αλ / d} = {8, 1.35, 500-517, 8.2 × 10 −2 , 80}
A porous carbon membrane having the following structural parameters.
　上記は、ペリクル膜として好ましい特徴的構造の例を、構造パラメータ群及び制約条件の値の各範囲を用いて示したが、数式を用いても、ＥＵＶ光が炭素多孔膜を１回通過する際の透過率Ｔが８４％以上、散乱量Δが１０％以下、膜厚Ｄが１００ｎｍ以上となるＥＵＶ用ペリクル膜を示すことができる。例えば、上記のＧ－Ｓｏｌｖｅｒを用いて計算すれば、ＥＵＶ光の波長λを１３．５ｎｍ、黒鉛の密度Ｗを２．２５ｇ／ｃｍ３、炭素多孔体膜の見かけ密度（ｇ／ｃｍ３）をρ、膜厚をＤ（ｎｍ）としたとき、第一構造パラメータを用いて、立方体壁組細孔モデルでは、炭素多孔体膜が、以下の各式（１）～（５）の構造パラメータの範囲を満たすＥＵＶ用ペリクル膜が好ましいとすることができる。
α≦３０（α：細孔サイズパラメータ）　…（１）
０．３３５≦Ｎｄ≦１３（Ｎ：膜厚方向への細孔数（個）、ｄ：細孔の壁厚（ｎｍ））　…（２）
αλ／ｄ≦８１（λ：露光波長（ｎｍ））　…（３）
ただし、上記Ｎ、ｄは、
Ｎ＝－１＋｛（Ｗ－ρ）１／３／Ｗ１／３｝＋｛Ｄ（Ｗ－ρ）１／３／αλＷ１／３｝　…（４）
ｄ＝－αλ＋｛αλＷ１／３／（Ｗ－ρ）１／３｝　…（５） The above shows an example of a characteristic structure preferable as a pellicle film, using each range of the value of the structural parameter group and the constraint condition. However, when EUV light passes through the carbon porous film once even using mathematical formulas. An EUV pellicle film having a transmittance T of 84% or more, a scattering amount Δ of 10% or less, and a film thickness D of 100 nm or more can be shown. For example, when calculating using the above G-Solver, the wavelength λ of EUV light is 13.5 nm, the density W of graphite is 2.25 g / cm 3 , and the apparent density (g / cm 3 ) of the porous carbon film is When ρ and the film thickness are D (nm), using the first structural parameter, in the cubic wall set pore model, the carbon porous body film has the structural parameters of the following equations (1) to (5). A pellicle film for EUV that satisfies the range may be preferable.
α ≦ 30 (α: pore size parameter) (1)
0.335 ≦ Nd ≦ 13 (N: number of pores in the film thickness direction (pieces), d: wall thickness of the pores (nm)) (2)
αλ / d ≦ 81 (λ: exposure wavelength (nm)) (3)
However, the above N and d are
N = −1 + {(W−ρ) 1/3 / W 1/3 } + {D (W−ρ) 1/3 / αλW 1/3 } (4)
d = −αλ + {αλW 1/3 / (W−ρ) 1/3 } (5)
　同様に、第二構造パラメータを用いて、立方体壁組細孔モデルでは、炭素多孔体膜が、以下の各式（６）～（９）の構造パラメータの範囲を満たすＥＵＶ用ペリクル膜が好ましいとすることができる。
α≦３０（α：細孔サイズパラメータ）　…（６）
αλ／ｄ≦８１（λ：露光波長（ｎｍ））　…（７）
０．０８ｇ／ｃｍ３≦ρ≦０．７ｇ／ｃｍ３　…（８）
Ｄ：１００ｎｍ≦Ｄ≦８５０ｎｍ　…（９） Similarly, in the cubic wall set pore model using the second structural parameter, it is preferable that the pellicle membrane for EUV satisfies the range of the structural parameters of the following formulas (6) to (9) in the carbon porous membrane can do.
α ≦ 30 (α: pore size parameter) (6)
αλ / d ≦ 81 (λ: exposure wavelength (nm)) (7)
0.08 g / cm 3 ≦ ρ ≦ 0.7 g / cm 3 (8)
D: 100 nm ≦ D ≦ 850 nm (9)
　このように、適切な計算手法のもと露光波長λ、近似する細孔構造モデルに対応して、ＥＵＶ用ペリクル膜として好ましい特徴的構造を、数式を用いても示すことができる。 As described above, a characteristic structure preferable as a pellicle film for EUV can be shown using mathematical formulas corresponding to the exposure wavelength λ and the approximate pore structure model under an appropriate calculation method.
　以上、［技術ポイント１］及び［技術ポイント２］から、本実施形態は、ペリクル膜であって、炭素多孔体膜で構成されており、且つ［技術ポイント３］からペリクル膜の膜厚Ｄが１００ｎｍ～６３μｍであることを特徴とする、ペリクル膜である。 As described above, from [Technical Point 1] and [Technical Point 2], the present embodiment is a pellicle film, which is composed of a porous carbon film, and from [Technical Point 3], the film thickness D of the pellicle film is A pellicle film having a thickness of 100 nm to 63 μm.
　なお、本実施形態の炭素多孔膜の更なる改善案［補足処理］として、公知な技術を組み合わせたものも挙げることができる。 In addition, what combined the well-known technique can also be mentioned as the further improvement plan [supplementary process] of the carbon porous membrane of this embodiment.
　第１の例は、特許文献２に記載のように、本実施形態の炭素多孔膜の表面の片面又は両面に、ＥＵＶの高出力光源からの光による炭素多孔膜の酸化・還元を防止するために、Ｓｉ、ＳｉＣ、ＳｉＯ２、Ｓｉ３Ｎ４、イットリウムＹ、モリブデンＭｏ、Ｒｕ、ロジウムＲｈ等を本発明の課題の目標値を満足する範囲内で、公知のスパッタ法、真空蒸着法等の方法で数ｎｍ被覆することである。Ｓｉは、ＥＵＶ光の消光係数が低く、屈折率が１．０に近く、炭素と反応し炭素膜表面に強度的に優れた数ｎｍのＳｉＣ膜を形成することから特に好ましい。 As described in Patent Document 2, the first example is to prevent oxidation / reduction of the porous carbon film by light from a high-power EUV light source on one or both surfaces of the porous carbon film of the present embodiment. In addition, Si, SiC, SiO 2 , Si 3 N 4 , Yttrium Y, Molybdenum Mo, Ru, Rhodium Rh, etc., within a range satisfying the target value of the subject of the present invention, such as a known sputtering method, vacuum deposition method, etc. The method is to coat several nm. Si is particularly preferred because it has a low extinction coefficient of EUV light, a refractive index close to 1.0, and reacts with carbon to form a SiC film having a few nm with excellent strength on the carbon film surface.
　第２の例は、本実施形態の炭素多孔膜は、ＥＵＶ光に対し、高い透過性と、実用的に十分な耐久性を有する膜厚を有するが、更なる膜強度が必要とされる場合、本発明の課題の目標値を満足する範囲内で、特許文献３、特許文献４、特許文献５、非特許文献２のようにメッシュを支持膜として（材料はＳｉ、Ｚｒ、Ｍｏ、チタンＴｉ、ニッケルＮｉ、アルミウムＡｌ、銅Ｃｕ等及びそれらの炭化物が、消光係数及びΔｎが小さく、汎用品として入手が容易であるという観点から好ましい）接合補強することである。この場合、支持膜（メッシュの厚みが数十μｍ、メッシュを構成する線径が数十μｍ、孔部の大きさが数百μｍ～数ｍｍの膜）により透過率が１０％以上下がるので、本発明の炭素多孔膜単独の透過率ＴはＴ２、Ｔ３のものを用いることとなる。なお、支持膜は散乱量Δにはほとんど影響を与えない。 In the second example, the carbon porous film of the present embodiment has a film thickness having high transparency and practically sufficient durability for EUV light, but when further film strength is required. As long as the target value of the problem of the present invention is satisfied, the mesh is used as a supporting film as in Patent Document 3, Patent Document 4, Patent Document 5, and Non-Patent Document 2 (materials are Si, Zr, Mo, titanium Ti Nickel nickel, aluminum Al, copper Cu, and their carbides are preferable from the viewpoint of having a small extinction coefficient and Δn, and being easily available as a general-purpose product). In this case, the transmittance is lowered by 10% or more by the support membrane (mesh having a mesh thickness of several tens of μm, a wire diameter constituting the mesh of several tens of μm, and a pore size of several hundred μm to several mm), The transmittance T of the carbon porous membrane alone of the present invention is T2, T3. Note that the support film hardly affects the scattering amount Δ.
　［追記］として、構造パラメータの補正法について述べる。［技術ポイント３］における式（１９）～式（４０）、式（１）～式（５）、式（６）～式（９）で示した、本実施形態の透過率Ｔ、散乱量Δと炭素多孔膜の構造パラメータ群との関係式や、Ｔ、Δ、Ｄの基準値を得るための構造パラメータ群を用いた制約範囲は、（前提１）及び（前提２）のもと、ＥＵＶ光の波長λ＝１３．５及びλ＝６．７５ｎｍのときの、密度Ｗ＝２．２５ｇ／ｃｍ３の黒鉛の光学定数ｎ、ｋの値を用いて透過率Ｔ及び散乱量Δを計算し、算出したものである。したがって、黒鉛の密度Ｗの前提値を変えた場合には対応する新たな光学定数を用いて、ステップ１～ステップ３と同様にしてＴ及びΔを再計算し、本実施形態の炭素多孔膜の構造パラメータの制約範囲やＴｉ、Δｉ、Ｄｉを再算出すればよい。例えば、黒鉛の密度Ｗの前提値が小さくなると、炭素の消光係数ｋが低くなり、屈折率ｎは１に近づくため、構造パラメータの厚みＤ、見かけ密度ρ、細孔サイズパラメータαの本実施形態の制限の範囲が広がることとなる。 As [Additional Notes], a method for correcting the structure parameter will be described. The transmittance T and scattering amount Δ of the present embodiment represented by the equations (19) to (40), the equations (1) to (5), and the equations (6) to (9) in [Technical Point 3]. The relational expression between the structural parameter group of the carbon porous membrane and the structural parameter group for obtaining the reference values of T, Δ, and D are EUV under (Premise 1) and (Premise 2). Using the values of optical constants n and k of graphite with a density W = 2.25 g / cm 3 when light wavelengths λ = 13.5 and λ = 6.75 nm, transmittance T and scattering amount Δ are calculated. , Calculated. Therefore, when the assumption value of the density W of graphite is changed, T and Δ are recalculated in the same manner as in Step 1 to Step 3 using the corresponding new optical constant, and the carbon porous film of this embodiment is What is necessary is just to recalculate the restriction range of structure parameters, Ti, Δi, and Di. For example, when the premise value of the density W of graphite decreases, the extinction coefficient k of carbon decreases and the refractive index n approaches 1, so this embodiment of the thickness D, the apparent density ρ, and the pore size parameter α of the structural parameters The range of restrictions will be expanded.
２－２．本実施形態のペリクル膜の製造方法
　本実施形態のペリクル膜の製造方法を以下に紹介するが、本実施形態のペリクル膜としての炭素多孔膜は、この製造方法及びその実施例に限定されるものではない。図５は、ペリクル膜の製造方法を示す図である。 2-2. Method for Producing Pellicle Membrane According to this Embodiment A method for producing a pellicle membrane according to this embodiment will be introduced below. The porous carbon film as the pellicle membrane according to this embodiment is limited to this production method and its examples. is not. FIG. 5 is a diagram showing a method for manufacturing a pellicle film.
　炭素多孔膜を得る方法には、次の様な方法がある。第１の方法は、焼結・炭化時に溶融・破壊することのない、目標とする細孔サイズの等倍～数十倍程度の微細な炭素前駆体粒子や炭素粒子にバインダーを加えて混合・成膜した後、焼結・炭化することで、粒子の隙間を細孔とした炭素多孔膜を得る方法である。 There are the following methods for obtaining a carbon porous membrane. The first method is to add a binder to fine carbon precursor particles or carbon particles that are about the same size to several tens of times the target pore size and do not melt or break during sintering and carbonization. This is a method of obtaining a porous carbon film having pores between the particles by sintering and carbonizing after film formation.
　第２の方法（方法Ａ）は、ゾル－ゲル法により、初めにゾル－ゲル転移する原料を用いて、溶媒を多量に含んだ溶媒和ゲル（例えばヒドロゲル）の膜を形成し、続いてその溶媒和の構造が潰れないように溶媒だけを乾燥除去することで多量に気泡を含むエアロゲル膜を得て、最終的にそのエアロゲル膜を炭化することで、炭素エアロゲルとしての炭素多孔膜を得る方法である。 In the second method (Method A), a solvated gel film (for example, hydrogel) containing a large amount of solvent is formed by using a raw material that first undergoes sol-gel transition by a sol-gel method. A method of obtaining a carbon porous film as a carbon aerogel by obtaining aerogel film containing a large amount of bubbles by drying and removing only the solvent so that the solvation structure does not collapse, and finally carbonizing the aerogel film It is.
　第３の方法（方法Ｂ）は、分子構造中に化学反応過程や炭化過程で構造が固定化すると共に気泡が発生する原料を用いて、化学反応や炭化反応をさせ、それらの過程で発生する気泡又は隙間を細孔とした炭素多孔膜を得る方法である。第１の方法より、粒径を制御し、ＥＵＶ光の波長の０．５倍～１０倍程度の細孔径を有する炭素多孔膜を製造することは他の方法に比べ比較的容易ではあるが、見かけ密度１．０ｇ／ｃｍ３以下の低密度の炭素多孔膜を得ることは難しい。本実施形態の炭素多孔膜は、第２及び第３の方法によって得ることができる。 In the third method (Method B), a chemical reaction or a carbonization reaction is performed using a raw material in which a structure is fixed in a molecular structure in a chemical reaction process or a carbonization process and bubbles are generated. This is a method for obtaining a carbon porous membrane having pores of air bubbles or gaps. From the first method, it is relatively easy to control the particle size and produce a porous carbon membrane having a pore diameter of about 0.5 to 10 times the wavelength of EUV light, compared to other methods. It is difficult to obtain a low-density carbon porous film having an apparent density of 1.0 g / cm 3 or less. The porous carbon membrane of this embodiment can be obtained by the second and third methods.
　本実施形態の炭素多孔膜は、［技術ポイント２］の第２の利点でも触れたように、既存の炭素多孔膜の製造技術を応用する。ただし、それらの製造技術とは、２つの点、［技術ポイント４］、［技術ポイント５］で異なるものとなる。 The carbon porous membrane of this embodiment applies the existing carbon porous membrane manufacturing technology as mentioned in the second advantage of [Technical Point 2]. However, these manufacturing techniques differ in two points, [Technical Point 4] and [Technical Point 5].
［技術ポイント４］
　技術ポイント４は、薄膜の成膜技術を導入することである。技術ポイント４は、本実施形態の炭素多孔膜の用途が、既存の炭素多孔膜の用途として全く考えられていなかったペリクル膜であるため、薄膜を得るための成膜技術が追加されていることである。すなわち、後述する本実施形態の炭素多孔膜の製造方法の中の、薄膜化に適した成膜工程（工程Ａ２、工程Ｂ２、工程ＡＢ２）及び薄膜を得るための塗工液の調合工程（工程Ａ１、工程Ｂ１、工程ＡＢ１）が重要な技術ポイントとなる。 [Technical point 4]
Technology point 4 is to introduce thin film deposition technology. Technical point 4 is that the use of the porous carbon membrane of the present embodiment is a pellicle membrane that was not considered at all as an application of the existing porous carbon membrane, so that a film forming technology for obtaining a thin film is added. It is. That is, in the manufacturing method of the carbon porous membrane of this embodiment described later, a film forming step suitable for thinning (step A2, step B2, step AB2) and a coating liquid preparation step for obtaining a thin film (step) A1, process B1, and process AB1) are important technical points.
　調合工程では、塗工液の組成、分子量、温度を調整し、塗工液の粘度を下げ、成膜・乾燥後の膜厚が数十ｎｍ～数百μｍに薄膜塗工できるようにすることが好ましい。構造固定・乾燥工程（工程Ａ３、工程Ｂ３、工程ＡＢ３）や炭化工程（工程Ａ４、工程Ｂ４、工程ＡＢ４）で膜厚が塗工時の約０．５倍～３倍となり、炭化後の膜厚が１００ｎｍ～６３μｍとなるためである。塗工液の粘度を下げるには、技術ポイント５で述べる製造パラメータの範囲内で塗工液中の最終的に炭素質となる溶質の濃度を下げればよい。特に、塗工液が高分子溶液である場合、乾燥後に塗工時の基材から塗膜を剥離する際に塗膜が破損しない強度を有する程度まで分子量を下げることが好ましい。 In the blending process, the composition, molecular weight, and temperature of the coating liquid are adjusted, the viscosity of the coating liquid is lowered, and the film thickness after film formation / drying can be applied to a film thickness of several tens to several hundreds of micrometers. Is preferred. Film thickness after the carbonization is about 0.5 to 3 times the coating thickness in the fixing / drying process (process A3, process B3, process AB3) and carbonization process (process A4, process B4, process AB4) This is because the thickness becomes 100 nm to 63 μm. In order to reduce the viscosity of the coating solution, the concentration of the solute that finally becomes carbonaceous in the coating solution may be reduced within the range of the manufacturing parameters described in Technical Point 5. In particular, when the coating solution is a polymer solution, it is preferable to lower the molecular weight to such an extent that the coating film does not break when it is peeled off from the base material at the time of coating after drying.
　また、薄膜を得るための塗工方法としては、蒸着法に代表されるドライコート法ではなく、低粘度の塗工液を薄く塗工できるウエット塗工法を用いることが好ましい。具体的には、スピンコート法、ノズルスキャン塗布法、インクジェット塗布法等のように生産性は低いが薄膜化に有利な塗工法やバーコート、グラビアコート、ダイコート、ドクターコート、キスコート等の薄膜化には限界があるがロールトゥロールと呼ばれる連続的塗工により生産性の高い塗工法を用いることができる。更に、塗工液粘度・組成や塗工方法を適正に調整・選択するだけでなく、塗工速度や塗工温度、塗工時間等の塗工条件を調整することで、均一な薄膜を得ることができる。 Further, as a coating method for obtaining a thin film, it is preferable to use a wet coating method capable of thinly coating a low-viscosity coating solution, not a dry coating method typified by a vapor deposition method. Specifically, coating methods that are low in productivity, such as spin coating, nozzle scan coating, and ink jet coating, but thin films such as bar coating, gravure coating, die coating, doctor coating, and kiss coating are advantageous. Although there is a limit, a coating method with high productivity can be used by continuous coating called roll-to-roll. Furthermore, it is possible to obtain a uniform thin film by adjusting the coating conditions such as coating speed, coating temperature, and coating time as well as adjusting and selecting the coating solution viscosity, composition and coating method appropriately. be able to.
［技術ポイント５］
　技術ポイント５は、［技術ポイント３］で述べた構造パラメータを有する炭素多孔膜を得るために、各製造方法に応じて製造パラメータ（炭素質となる溶質の種類とその分子量、溶液組成、溶液濃度、架橋触媒種・脱ハロゲン種とその濃度、乾燥条件、炭化条件等）を調整することであり、以下にその詳細を述べる。 [Technical point 5]
In order to obtain a carbon porous membrane having the structural parameters described in [Technical Point 3], the technical point 5 is a manufacturing parameter (the kind and molecular weight of the carbonaceous solute, the solution composition, the solution concentration) according to each manufacturing method. The crosslinking catalyst species / dehalogenation species and their concentrations, drying conditions, carbonization conditions, etc.) are adjusted, and the details will be described below.
２－２－１．炭素エアロゲル系炭素多孔膜の製造方法
　本実施形態の炭素多孔膜を得る方法Ａ（上述の第２の方法）は、参考文献Ａ、米国特許ＵＳ４８７３２１８号公報［以下、参考文献Ｂとする］、田門肇、表面、３８（１）、１－９（２０００）［以下、参考文献Ｃとする］、特表平８－５０８５３５公報［以下、参考文献Ｄとする］、及び、Ｒ．Ｓａｌｉｇｅｒ等、Ｊ．Ｎｏｎ－Ｃｒｙｓｔａｌｌｉｎｅ　Ｓｏｌｉｄｓ、２２１、１４４－１５０（１９９７）［以下、参考文献Ｅとする］に紹介されている方法を応用する。これらの文献では、断熱材、電池やキャパシタ等に用いるメソ孔を有する炭素材料として紹介され、本実施形態の用途は全く考慮されていない。しかし、薄膜の成膜技術を追加し、膜厚の薄いヒドロゲル膜が得られるように製造パラメータを調整することで、本実施形態の用途に応用することができる。 2-2-1. Method for Producing Carbon Airgel-Based Carbon Porous Membrane Method A (the second method described above) for obtaining the carbon porous membrane of this embodiment includes Reference A, US Pat. No. 4,873,218 [hereinafter referred to as Reference B], Monden, Surface, 38 (1), 1-9 (2000) [hereinafter referred to as Reference C], JP-T 8-508535 [hereinafter referred to as Reference D]; Saliger et al. The method introduced in Non-Crystalline Solids, 221, 144-150 (1997) [hereinafter referred to as Reference E] is applied. In these documents, a carbon material having mesopores used for a heat insulating material, a battery, a capacitor, or the like is introduced, and the application of this embodiment is not considered at all. However, it can be applied to the application of the present embodiment by adding a thin film forming technique and adjusting manufacturing parameters so as to obtain a thin hydrogel film.
　すなわち、図５に示されるように、工程Ａ１として、炭素質原料としてレゾルシノール（Ｒ）、フェノール、カテコール、フロログルシノール及び他のポリヒドロキシ－ベンゼン化合物からなるいづれか１つ以上のモノマーと、ホルムアルデヒド（Ｆ）、フルフラールのいずれか１つ以上のモノマーとを、またゲル化（重合）のアルカリ触媒（Ｃａ）として炭酸カリウム（Ｋ２ＣＯ３）、炭酸ナトリウム（Ｎａ２ＣＯ３）、炭酸水素カリウム（ＫＨＣＯ３）、炭酸水素ナトリウム（ＮａＨＣＯ３）等のアルカリ金属炭酸塩、アルカリ金属炭酸水素塩のいずれか１つ以上を水（Ｗａ）に溶かし、これらを混合して塗工液Ａ（ＲＦ粘凋液）を調合する。 That is, as shown in FIG. 5, in step A1, as the carbonaceous raw material, one or more monomers consisting of resorcinol (R), phenol, catechol, phloroglucinol and other polyhydroxy-benzene compounds, and formaldehyde ( F) and one or more monomers of furfural, and also as an alkali catalyst (Ca) for gelation (polymerization), potassium carbonate (K 2 CO 3 ), sodium carbonate (Na 2 CO 3 ), potassium hydrogen carbonate ( Any one or more of alkali metal carbonates such as KHCO 3 ) and sodium hydrogen carbonate (NaHCO 3 ) and alkali metal hydrogen carbonate are dissolved in water (Wa), and these are mixed to form coating solution A (RF viscosity). Liquid).
　工程Ａ２として、工程Ａ１に引き続き、この塗工液Ａを後から剥離させやすいように離形フィルムや離形基板上に、炭化後の膜厚が１００～８５０ｎｍになるように塗工（前述のバーコートやスピンコート等）・成膜する。この際、離形フィルムや離形基板の周りを取り囲む共に密閉し、塗膜が離形フィルムや離形基板の周囲から流出しないように、且つ溶媒（水）が蒸発して塗工液の組成が変化したり、膜細孔となる領域が潰れたりしないように密封しておくことが好ましい。 As step A2, following step A1, the coating liquid A is coated on a release film or release substrate so that the film thickness after carbonization becomes 100 to 850 nm so that it can be easily peeled later (as described above). Bar coating, spin coating, etc.) / Film formation. At this time, the surroundings of the release film and the release substrate are hermetically sealed, the coating film does not flow out of the release film and the release substrate, and the solvent (water) evaporates and the composition of the coating liquid It is preferable to seal so that the region which becomes the membrane pores is not crushed.
　工程Ａ３として、工程Ａ２に引き続き、室温（２０℃）～１００℃で段階的に温度を高めたり、数日間（１～１４日間）静置したりして、十分にゲル化（重合）させ、薄膜状のヒドロゲル膜を得る。固形のヒドロゲル膜を早く得るためには、参考文献Ｄに示されたように、静置の際に加熱（５０～１００℃）することができるが、大きな細孔径を有するヒドロゲル膜を得るには加熱温度は低いことが好ましい。 As step A3, subsequent to step A2, the temperature is raised stepwise from room temperature (20 ° C.) to 100 ° C. or allowed to stand for several days (1 to 14 days) to sufficiently gel (polymerize), A thin-film hydrogel film is obtained. In order to obtain a solid hydrogel membrane quickly, as shown in Reference Document D, heating (50 to 100 ° C.) can be performed during standing, but to obtain a hydrogel membrane having a large pore diameter. The heating temperature is preferably low.
　続いて、ヒドロゲル膜を離形フィルムや離形基板から剥離し、細孔径・細孔形状をより保持できるように乾燥するため、ヒドロゲル膜中の溶媒（水）をアセトンやシクロヘキサン等で置換して二酸化炭素超臨界乾燥（ＣＯ２超臨界乾燥）したり［乾燥法１］、凍結乾燥（必要ならばｔ－ブタノール等で置換した後に）したり［乾燥法２］、室温～１００℃で熱風乾燥又は減圧乾燥（熱風・減圧乾燥）（必要ならば乾燥法１または乾燥法２で用いた処理液で置換した後）したり［乾燥法３］して、ヒドロゲル膜中の水を飛散して多孔性のＲＦ系エアロゲル膜を得る。置換にあたっては、置換液との接触による細孔径、細孔形状の変化を抑えるためにヒドロゲル膜中の水からアセトン、シクロヘキサン、ｔ－ブタノール等への置換濃度を徐々に高めたり、置換回数を増やしたりすることが好ましい。 Subsequently, the hydrogel film is peeled off from the release film or release substrate, and dried so that the pore diameter and shape can be more maintained, so that the solvent (water) in the hydrogel film is replaced with acetone or cyclohexane. Carbon dioxide supercritical drying (CO 2 supercritical drying), [Drying method 1], freeze-drying (after replacement with t-butanol if necessary) [Drying method 2], hot air drying at room temperature to 100 ° C. Or, drying under reduced pressure (hot air / vacuum drying) (after replacement with the treatment liquid used in drying method 1 or drying method 2 if necessary) or [drying method 3] to disperse the water in the hydrogel film and make it porous RF-based airgel membrane is obtained. In substitution, in order to suppress changes in pore diameter and pore shape due to contact with the substitution liquid, the substitution concentration from water in the hydrogel membrane to acetone, cyclohexane, t-butanol, etc. is gradually increased or the number of substitutions is increased. Is preferable.
　また、乾燥方法としては、乾燥時の溶媒の界面張力による毛管収縮をできるだけ抑えるため、［乾燥法１］が最も好ましい。しかし、超臨界乾燥の替わりに参考文献Ｃに示された［乾燥法２］、参考文献Ｄ、参考文献Ｅに示された［乾燥法３］も、細孔径・細孔形状を多少の犠牲にする（収縮する）ことになるが、製造コストを低く抑えるには優位になり、本実施形態に用いることができる。 Also, as the drying method, [Drying method 1] is most preferable in order to suppress capillary contraction due to the interfacial tension of the solvent during drying as much as possible. However, instead of supercritical drying, [Drying Method 2] shown in Reference C, Reference D, and [Drying Method 3] shown in Reference E also sacrifice some pore diameter and pore shape. However, it is advantageous to keep the manufacturing cost low and can be used in this embodiment.
　工程Ａ４として、工程Ａ３に引き続き、ＲＦ系エアロゲル膜を不活性雰囲気下又は窒素雰囲気下で、６００～３０００℃で１０分～２０時間炭化処理を行い、本実施形態のＲＦ系炭素エアロゲルとしての炭素多孔膜を得る。炭化処理は、炭素前駆体を粉砕することなく、固形フィルム、シートの炭化・賦活処理に使われる固定床方式、移動床方式、トンネルキルン等の炭化・賦活製造方式を使うことができる。 As step A4, subsequent to step A3, the RF airgel film is carbonized at 600 to 3000 ° C. for 10 minutes to 20 hours in an inert atmosphere or nitrogen atmosphere, and carbon as the RF carbon aerogel of this embodiment is obtained. A porous membrane is obtained. The carbonization treatment can use a carbonization / activation production method such as a fixed bed method, a moving bed method, and a tunnel kiln used for carbonization / activation treatment of solid films and sheets without crushing the carbon precursor.
　炭化に伴い、ＲＦ系エアロゲルの細孔径は収縮し、炭化温度が高くなるほど収縮の割合は低下するが、細孔径、細孔分布は小さくなる傾向を有する。したがって、目標とする細孔径に応じて炭化温度を調整することができる。通常、炭化温度は７００～１５００℃で行い、更に膜強度、導電性、熱伝導性を高める必要がある場合は２０００～３０００℃で処理を行うことができる。また、得られた炭素多孔膜を必要に応じて賦活処理を行い、細孔径及び細孔分布を大きくすることで細孔構造を調整することもできる。賦活方法としては、水蒸気、塩化水素、一酸化炭素、二酸化炭素、酸素等の賦活ガスを用いて焼成するガス賦活法を用いることが好ましい。 With the carbonization, the pore diameter of the RF airgel shrinks, and the rate of shrinkage decreases as the carbonization temperature increases, but the pore diameter and pore distribution tend to be smaller. Therefore, the carbonization temperature can be adjusted according to the target pore diameter. Usually, the carbonization temperature is 700 to 1500 ° C., and when it is necessary to further increase the film strength, conductivity and thermal conductivity, the treatment can be performed at 2000 to 3000 ° C. In addition, the pore structure can be adjusted by subjecting the obtained carbon porous membrane to an activation treatment as necessary to increase the pore diameter and pore distribution. As the activation method, it is preferable to use a gas activation method in which firing is performed using an activation gas such as water vapor, hydrogen chloride, carbon monoxide, carbon dioxide, oxygen, or the like.
　なお、炭化処理の際、エアロゲル膜は大きく収縮し、無緊張状態で炭化すると膜にシワが発生しやすいため、枠で固定したり、２枚の黒鉛板や黒鉛シート間に挟む等を行い、エアロゲル膜を緊張下で炭化したり、空気中又はヨウ素（Ｉ２）蒸気下、１５０℃～２５０℃で事前に構造の熱安定化を行うことが好ましい。 In addition, during the carbonization treatment, the airgel film shrinks greatly, and if carbonized in a non-tensioned state, the film tends to wrinkle, so it is fixed with a frame or sandwiched between two graphite plates or graphite sheets, It is preferable to carbonize the airgel membrane under tension, or to thermally stabilize the structure in advance at 150 ° C. to 250 ° C. in air or iodine (I 2 ) vapor.
　参考文献Ｃ中の図１、及び、Ｒ．Ｗ．Ｐｅｋａｌａ、Ｆ－Ｍ．Ｋｏｎｇ、Ｐｏｌｙｍ.、Ｐｒｅｐ、３０、２２１－２２３（１９８９）［以下、参考文献Ｆとする］中の図２には、ＲＦ系エアロゲルの形成機構の模式図、ＲＦ系エアロゲル及びその炭化物としてのＲＦ系炭素エアロゲルの電子顕微鏡写真が記載されている。 Figure 1 in Reference C and R. W. Pekala, FM. FIG. 2 in Kong, Polym., Prep, 30, 221-223 (1989) [hereinafter referred to as Reference Document F] shows a schematic diagram of the formation mechanism of RF airgel, RF airgel and RF as a carbide thereof. Electron micrographs of carbon-based carbon aerogels are described.
　数珠状の微粒子の集合体がＲＦ系炭素エアロゲルとしての炭素多孔膜を形成している。現実の炭素多孔膜は、立方体軸組細孔構造モデルと立方体壁組細孔構造モデルとの中間的な構造を有すると考えられるが、敢えて言えばＲＦ系炭素エアロゲルの細孔構造は、立方体軸組細孔構造モデルに似た構造であることが分かる。 An aggregate of beaded fine particles forms a carbon porous film as an RF carbon aerogel. An actual carbon porous membrane is considered to have an intermediate structure between a cubic axial pore structure model and a cubic wall porous structure model. It can be seen that the structure is similar to the assembled pore structure model.
　また、参考文献Ａ中の図１０～図１３には、ＲＦ系炭素エアロゲルの細孔分布のグラフとＳＡＸＳのＤｅｂｙｅ－Ｐｏｒｏｄ解析のグラフが記載されている。同文献の図１０から、ＲＦ系炭素エアロゲルの細孔分布への触媒種の依存性として、アルカリ金属炭酸塩より、アルカリ金属炭酸水素塩の方が大きなピーク細孔半径ｒ（ｐｅａｋ）、細孔径Ｌが得られることが、同文献の図１２からＲ／Ｃの依存性として、Ｒ／Ｃが大きくなると細孔径Ｌは大きくなるが、細孔分布はブロードとなり、細孔分布曲線の山のピーク高さも低くなることが分かる。 Also, FIGS. 10 to 13 in Reference Document A contain graphs of the pore distribution of RF-based carbon airgel and graphs of SAXS Debye-Porod analysis. From FIG. 10 of the same document, as the dependence of the catalyst species on the pore distribution of the RF carbon aerogel, the peak pore radius r (peak) and the pore diameter of the alkali metal bicarbonate are larger than those of the alkali metal carbonate. From FIG. 12 of the same document, L is obtained as the dependency of R / C. As R / C increases, the pore diameter L increases, but the pore distribution becomes broad, and the peak of the peak of the pore distribution curve It can be seen that the height also decreases.
　また、同文献の図１３より、細孔形状は、Ｒ／Ｃが数１００（例えば２００）以下ならば、Ｄｅｂｙｅ－Ｐｏｒｏｄプロットの直線の傾きが－４に近いことから触媒種に関係なく球状に近いことが分かる。 From FIG. 13 of the same document, the pore shape is spherical regardless of the catalyst type because the slope of the Debye-Porod plot is close to −4 when the R / C is several hundred (eg, 200) or less. You can see that they are close.
　以下に、参考文献Ａ、参考文献Ｂ、参考文献Ｃに記載された代表的な実験値から、工程Ａ１として炭素質となる原料にＲ、Ｆを、ＣａとしてＮａ２ＣＯ３を様々な組成比の塗工液Ａを調合し、工程Ａ２として塗工液Ａをスピンコートにて薄膜成膜してヒドロゲル膜を得た後、工程Ａ３としてヒドロゲル膜を室温～１００℃でゲル化（重合）させ、ＣＯ２超臨界乾燥又は凍結乾燥又は熱風乾燥を行ってエアロゲル膜を得た後、工程Ａ４としてエアロゲル膜を１０００℃で炭化処理を行ない、最終的に本実施形態の炭素多孔膜の得たものと仮定した時の、組成比と得られる構造パラメータとの重回帰式、式（３６）、式（３７）を求めた。見掛け密度は、
           ρ＝－１．２７×１０－１・ｌｎ（Ｒ／Ｃａ）＋７．０７・（Ｒ／Ｗａ）＋７．２４×１０－１　…（４５）
           Ｒ＊２＝０．９２
となり、各因子の依存率は、ｌｎ（Ｒ／Ｃａ）が３６％、Ｒ／Ｗａが６４％となった。 In the following, from typical experimental values described in Reference A, Reference B, and Reference C, R and F are used as raw materials that become carbonaceous as Step A1, and Na 2 CO 3 is used as various composition ratios as Ca. In Step A2, the coating liquid A was prepared as a thin film by spin coating to obtain a hydrogel film, and then in Step A3, the hydrogel film was gelled (polymerized) at room temperature to 100 ° C. , CO 2 supercritical drying or freeze drying or hot air drying to obtain an airgel membrane, and then the airgel membrane is carbonized at 1000 ° C. as step A4, and finally the carbon porous membrane of this embodiment is obtained The multiple regression equations of the composition ratio and the obtained structural parameters, Equation (36) and Equation (37) were obtained. Apparent density is
ρ = −1.27 × 10 −1 · ln (R / Ca) + 7.07 · (R / Wa) + 7.24 × 10 −1 (45)
R * 2 = 0.92
Thus, the dependency rate of each factor was 36% for ln (R / Ca) and 64% for R / Wa.
　また、細孔半径ｒは、
           ｌｎ（ｒ）＝２．４１×１０－１・ｌｎ（Ｒ／Ｃａ）－５．２３×１０－１・ｌｎ（Ｒ／Ｗａ）＋５．３６×１０－１・ｌｎ（Ｒ／Ｆ）－９．６９×１０－１　…（４６）
           Ｒ＊２＝０．７９
となり、各因子の依存率は、ｌｎ（Ｒ／Ｃａ）が３９％、ｌｎ（Ｒ／Ｗａ）が３７％、ｌｎ（Ｒ／Ｆ）が２５％となった。なお、細孔半径ｒに対応するαは、式（１８）に従い、ｒを２倍し、λで割ることで得られる。 The pore radius r is
ln (r) = 2.41 × 10 −1 · ln (R / Ca) −5.23 × 10 −1 · ln (R / Wa) + 5.36 × 10 −1 · ln (R / F) −9 .69 × 10 −1 (46)
R * 2 = 0.79
Thus, the dependency rate of each factor was 39% for ln (R / Ca), 37% for ln (R / Wa), and 25% for ln (R / F). Note that α corresponding to the pore radius r is obtained by doubling r and dividing by λ according to the equation (18).
　式（４５）及び式（４６）より、以下のことが分かる。ＲとＣａとのモル比Ｒ／Ｃａは増大するに伴い、見かけ密度ρは小さく、細孔半径ｒに対応するαが大きくなる。また、上記引用文献４によれば、Ｃａの種類の影響は、Ｋ２ＣＯ３≒Ｎａ２ＣＯ３＜ＮａＨＣＯ３＜ＫＨＣＯ３順でαが大きくなり、Ｒ／Ｃａが小さくなると細孔分布はシャープとなり、０＜Ｒ／Ｃａ≦２００では球状の細孔が、Ｒ／Ｃａ＞８００では円盤状の細孔が得られている。したがって、球状の大きな細孔でシャープな細孔分布を得るためには、アルカリ金属炭酸水素塩を用い、できるだけＲ／Ｃａを小さくすることが好ましい。 From the equations (45) and (46), the following can be understood. As the molar ratio R / Ca between R and Ca increases, the apparent density ρ decreases and α corresponding to the pore radius r increases. Further, according to the above cited reference 4, the influence of the type of Ca is such that K 2 CO 3 ≈Na 2 CO 3 <NaHCO 3 <KHCO 3 in order, α increases, and when R / Ca decreases, the pore distribution becomes sharper. Thus, when 0 <R / Ca ≦ 200, spherical pores are obtained, and when R / Ca> 800, disk-like pores are obtained. Therefore, in order to obtain a sharp pore distribution with large spherical pores, it is preferable to use an alkali metal hydrogen carbonate and make R / Ca as small as possible.
　一方、ＲとＷａとのモル比Ｒ／Ｗａは増大するに伴い、ρは大きく、αは小さくなる。また、ＲとＦとのモル比Ｒ／Ｆは増大するに伴い、αは大きくなる。したがって、大きな細孔を得るためには、Ｒ／Ｗａはできるだけ小さく、Ｒ／Ｆはできるだけ大きくすることが好ましい。 On the other hand, as the molar ratio R / Wa between R and Wa increases, ρ increases and α decreases. As the molar ratio R / F between R and F increases, α increases. Therefore, in order to obtain large pores, it is preferable to make R / Wa as small as possible and R / F as large as possible.
　更に、第２構造パラメータ群とＴ、Δとの重回帰式、すなわち立方体壁組細孔モデルで近似した場合には、λ＝１３．５ｎｍでは式（３３）、式（３４）を用いて、λ＝６．７５ｎｍでは式（３５）、式（３６）を用いて、立方体軸組細孔モデルで近似した場合には、λ＝１３．５ｎｍでは式（３７）、式（３８）を用いて、λ＝６．７５ｎｍでは式（３９）、式（４０）を用いることで、本実施形態の課題を満たすＴｉ、Δｉ、Ｄｉの組成範囲を知ることができる。 Furthermore, when approximated by a multiple regression equation of the second structural parameter group and T, Δ, that is, a cubic wall set pore model, at λ = 13.5 nm, using Equations (33) and (34), When λ = 6.75 nm is approximated by the cubic axis assembly pore model using Equations (35) and (36), when λ = 13.5 nm, Equations (37) and (38) are used. When λ = 6.75 nm, the composition range of Ti, Δi, and Di that satisfies the problems of the present embodiment can be known by using the equations (39) and (40).
　以上のように、ゾル－ゲル法により、初めにゾル－ゲル転移する原料を用いて、溶媒を多量に含んだ溶媒和ゲル（例えばヒドロゲル）の膜を形成し、続いてその溶媒和の構造が潰れないように溶媒だけを乾燥除去することで多量に気泡を含むエアロゲル膜を得て、最終的にそのエアロゲル膜を炭化することで、炭素エアロゲルとしての本実施形態の炭素多孔膜を得ることができる。 As described above, a solvated gel film (for example, hydrogel) containing a large amount of a solvent is formed by using a raw material that first undergoes a sol-gel transition by the sol-gel method. It is possible to obtain an airgel film containing a large amount of bubbles by drying and removing only the solvent so as not to be crushed, and finally carbonizing the airgel film to obtain the carbon porous film of this embodiment as a carbon airgel. it can.
２－２－２．ハロゲン化ビニル樹脂系又はハロゲン化ビニリデン樹脂系炭素多孔膜の製造法
　本実施形態の炭素多孔膜を得る方法Ｂ（上述の第３の方法）は、本発明者による特許４８７１３１９号公報［以下、参考文献Ｇとする］、山下順也、塩谷正俊、炭素、Ｎｏ２０４、１８２－１９１（２００２）［参考文献Ｈとする］に紹介されている方法を応用する。これらの参考文献Ｇや参考文献Ｈは、触媒担持材料、ガス吸蔵材料、ガス分離材料、電極材料等に用いるメソ孔を有する炭素材料の製造法に関するものとして紹介され、本実施形態への応用は全く考慮されていない。しかし、薄膜の成膜技術を追加し、膜厚の薄いハロゲン化ビニル樹脂膜又はハロゲン化ビニリデン樹脂膜が得られるように製造パラメータを調整することで、本実施形態の用途へ応用することができる。 2-2-2. Method for Producing Carbon Halogen Vinyl Resin-Based or Vinylidene Halide Resin Carbon Porous Membrane Method B (the third method described above) for obtaining the carbon porous membrane of the present embodiment is disclosed in Japanese Patent No. 4871319 [hereinafter referred to as reference]. Reference G], Junya Yamashita, Masatoshi Shiotani, Carbon, No. 204, 182-191 (2002) [referred to as Reference H] is applied. These references G and H are introduced as relating to a method for producing a carbon material having mesopores used for a catalyst support material, a gas storage material, a gas separation material, an electrode material, etc. It is not considered at all. However, it can be applied to the use of this embodiment by adding a thin film forming technique and adjusting the manufacturing parameters so that a thin vinyl halide resin film or vinylidene halide resin film can be obtained. .
　すなわち、図５に示すように、工程Ｂ１として、炭素質原料にハロゲン化ビニル組成６０モル％以上のハロゲン化ビニル樹脂又はハロゲン化ビニル共重合体の樹脂（総称してハロゲン化ビニル樹脂と呼ぶ）中のハロゲンの重量比が６０ｗｔ％以上の高ハロゲン化ビニル樹脂、又はハロゲン化ビニリデン組成６０モル％以上のハロゲン化ビニリデン又はハロゲン化ビニリデン共重合体の樹脂（総称してハロゲン化ビニリデン樹脂と呼ぶ）を用いる（以後、高ハロゲン化ビニル樹脂とハロゲン化ビニリデン樹脂とを同等に扱い、特に断わらなければ、簡単にハロゲン化ビニリデン樹脂と称することとする）。これらの樹脂を良溶媒に溶かした溶液又はハロゲン化ビニリデン樹脂の微粒子が水に分散したラテックスを調合し、これらの溶液及びラテックスを総称して塗工液Ｂと呼ぶ。 That is, as shown in FIG. 5, as step B1, a carbonaceous raw material is a vinyl halide resin or vinyl halide copolymer resin having a vinyl halide composition of 60 mol% or more (generically referred to as a vinyl halide resin). Highly halogenated vinyl resin having a halogen weight ratio of 60 wt% or more, or a vinylidene halide or vinylidene halide copolymer resin having a vinylidene halide composition of 60 mol% or more (collectively referred to as vinylidene halide resin) (Hereinafter, the high-halogenated vinyl resin and the vinylidene halide resin are treated in the same manner, and unless otherwise specified, simply referred to as the vinylidene halide resin). A solution in which these resins are dissolved in a good solvent or a latex in which fine particles of a vinylidene halide resin are dispersed in water is prepared. These solutions and latex are collectively referred to as a coating solution B.
　工程Ｂ２として、工程Ｂ１に引き続き、この塗工液Ｂを離形フィルムや離形基板上に、炭化後の膜厚が１００ｎｍ～６３μｍになるように塗工・成膜し、室温～溶媒の沸点以下の温度で熱風・減圧乾燥させて溶媒又は水を飛散し、薄膜状のハロゲン化ビニリデン樹脂の樹脂膜（ハロゲン化ビニリデン樹脂膜）を得る。 As step B2, following step B1, this coating solution B is applied and formed on a release film or release substrate so that the film thickness after carbonization is 100 nm to 63 μm. A solvent or water is scattered by drying with hot air and reduced pressure at the following temperature to obtain a thin film resin film of vinylidene halide resin (vinylidene halide resin film).
　工程Ｂ３として、工程Ｂ２に引き続き、ハロゲン化ビニリデン樹脂膜を、アルカリ金属水酸化物［水酸化カリウム（ＫＯＨ）、水酸化ナトリウム（ＮａＯＨ）等］の脱ハロゲン化水素剤（塩基）の水溶液及び／又はアミン溶液［アンモニア水（ＮＨ３水）、１、８－ジアザビシクロ［５、４、０］－７－ウンデセン（ＤＢＵ）等］の脱ハロゲン化水素剤（塩基）の溶液と、テトラヒドロフラン（ＴＨＦ）、ジメチルホルムアミド（ＤＭＦ）等のハロゲン化ビニリデン樹脂を一部又は全部溶解する良溶媒と、水、アルコール及び／又はエーテル等のハロゲン化ビニリデン樹脂の貧溶媒との混合溶液を用いて、室温～混合溶液の沸点以下の温度で１秒～２週間、脱ハロゲン化水素反応処理し、ハロゲン化ビニリデン樹脂系炭素前駆体膜を得る。なお、混合溶液は組成によっては、相分離をする場合がある。本実施形態で用いる混合溶液は、相分離をしない組成のものであり、炭素前駆体の脱ハロゲン化水素反応を再現性良く起こすには必須なものである。 As step B3, subsequent to step B2, the vinylidene halide resin film is changed to an aqueous solution of a dehydrohalogenating agent (base) of an alkali metal hydroxide [potassium hydroxide (KOH), sodium hydroxide (NaOH), etc.] and / or Or a solution of a dehydrohalogenating agent (base) in an amine solution [ammonia water (NH 3 water), 1,8-diazabicyclo [5,4,0] -7-undecene (DBU), etc.] and tetrahydrofuran (THF) Using a mixed solution of a good solvent for partially or entirely dissolving vinylidene halide resins such as dimethylformamide (DMF) and a poor solvent for vinylidene halide resins such as water, alcohol and / or ether, and mixing at room temperature to A dehydrohalogenation reaction treatment is performed at a temperature below the boiling point of the solution for 1 second to 2 weeks to obtain a vinylidene halide resin-based carbon precursor film. The mixed solution may undergo phase separation depending on the composition. The mixed solution used in the present embodiment has a composition that does not cause phase separation, and is essential for causing the dehydrohalogenation reaction of the carbon precursor with good reproducibility.
　工程Ｂ２及び工程Ｂ３においては、工程Ａ２及び工程Ａ３と異なり、離形フィルムや離形基板上の塗工膜のゲル化に時間を要したり、塗工膜を熱風乾燥させた後わざわざ剥離する操作をしたりせずに、塗工膜を直接混合溶液中に浸漬することもできる。混合溶液との接触により塗工膜の脱ハロゲン水素化による架橋（構造の固定化）が起こると同時に、発生する脱ハロゲン化水素ガスにより、離形フィルムや離形基板からハロゲン化ビニリデン樹脂膜が自然に剥離されるからである。したがって、方法Ａに比べ極めて短時間でハロゲン化ビニリデン樹脂膜を得ることができる。 In step B2 and step B3, unlike step A2 and step A3, it takes time to gel the release film or the coating film on the release substrate, or it is peeled off after the coating film is dried with hot air. It is also possible to immerse the coating film directly in the mixed solution without any operation. Contact with the mixed solution causes cross-linking (fixation of structure) of the coating film by dehalogenation, and at the same time, the generated dehydrohalogen gas causes the vinylidene halide resin film from the release film or release substrate. It is because it peels naturally. Therefore, a vinylidene halide resin film can be obtained in an extremely short time compared with Method A.
　更に、工程Ｂ３の塗工膜の脱ハロゲン水素化では、ハロゲン化ビニリデン樹脂膜中にポリエン構造（－Ｃ＝Ｃ－又はＣ≡Ｃ－を有する分子骨格構造を意味する）と呼ばれる架橋構造と脱ハロゲン化水素で生じた気泡を発生し、その気泡が膜中に多数残ったハロゲン化ビニリデン樹脂系炭素前駆体膜となる。この炭素前駆体膜は多数の架橋構造により、その後の工程Ｂ４でも、溶融することなく、更に脱ハロゲン化水素反応と炭化（非昌質炭素化、黒鉛化）が進行して行くことができる。 Further, in the dehydrohalogenation of the coating film in the step B3, a crosslinked structure called a polyene structure (meaning a molecular skeleton structure having —C═C— or C≡C—) in the vinylidene halide resin film is removed. Bubbles generated by the hydrogen halide are generated, and a large number of the bubbles remain in the vinylidene halide resin-based carbon precursor film remaining in the film. This carbon precursor film has a number of cross-linked structures, so that the dehydrohalogenation reaction and carbonization (non-destructive carbonization, graphitization) can proceed without melting even in the subsequent step B4.
　工程Ｂ４として、工程Ｂ３に引き続き、ハロゲン化ビニリデン樹脂系炭素前駆体膜を工程Ａ４と同様に不活性雰囲気下又は窒素雰囲気下で、６００～３０００℃で、１０分～２０時間、緊張下で加熱炭化を行い、本実施形態のハロゲン化ビニリデン樹脂系炭素多孔膜を得る方法である。 As step B4, following step B3, the vinylidene halide resin-based carbon precursor film is heated under tension at 600 to 3000 ° C. for 10 minutes to 20 hours in an inert atmosphere or nitrogen atmosphere as in step A4. In this method, carbonization is performed to obtain the vinylidene halide resin-based carbon porous film of the present embodiment.
　方法Ｂによる細孔径・細孔分布の制御としては、工程Ｂ１では樹脂中の高ハロゲン化ビニル及びハロゲン化ビニリデンの組成モル％、樹脂の分子量、塗工液Ｂ中の樹脂濃度で決まり、これらの値が高くなる程細孔径は小さくなる。また、工程Ｂ２では膜厚を薄くすることで膜中の細孔分布をシャープにすることができる。更に、工程Ｂ３では混合溶液中のアルカリ金属水酸化物、アミン等の塩基（脱ハロゲン化水素剤）の濃度が高いほど、混合溶液中のハロゲン化ビニリデン樹脂の良溶媒の濃度が高いほど細孔径が大きくなる。工程Ｂ４では工程Ａ４同様、炭化温度が高くなるほど細孔径は小さくなる傾向を有するが、炭素前駆体中の残存ハロゲン量によっては６００℃～１２００℃で細孔径・細孔分布を大きくすることもできる。更に、工程Ａ４同様、賦活処理により、細孔径及び細孔分布を大きくすることで細孔構造を調整することもできる。方法Ｂの例として、参考文献Ｇ、参考文献Ｈの例を以下に述べる。 Control of pore diameter and pore distribution by Method B is determined in Step B1 by the composition mol% of high vinyl halide and vinylidene halide in the resin, the molecular weight of the resin, and the resin concentration in the coating liquid B. The higher the value, the smaller the pore size. In Step B2, the pore distribution in the film can be sharpened by reducing the film thickness. Furthermore, in step B3, the higher the concentration of the base (dehydrohalogenating agent) such as alkali metal hydroxide and amine in the mixed solution, the higher the concentration of the good solvent of the vinylidene halide resin in the mixed solution, the larger the pore size. Becomes larger. In step B4, as in step A4, the pore diameter tends to decrease as the carbonization temperature increases. However, depending on the amount of residual halogen in the carbon precursor, the pore diameter / pore distribution can be increased at 600 ° C. to 1200 ° C. . Furthermore, the pore structure can also be adjusted by enlarging the pore diameter and the pore distribution by the activation treatment as in step A4. As examples of Method B, examples of Reference G and Reference H are described below.
　工程Ｂ１として、炭素質原料に塩化ビニリデン（ＶＤＣ）組成６０モル％以上の塩化ビニリデン樹脂又は塩化ビニリデン共重合体の樹脂（総称してＰＶＤＣ樹脂）を、ＰＶＤＣ樹脂の良溶媒としてＴＨＦを用いて溶解して塗工液Ｂを作る。 As Step B1, a vinylidene chloride resin or vinylidene chloride copolymer resin (collectively PVDC resin) having a vinylidene chloride (VDC) composition of 60 mol% or more is dissolved in a carbonaceous raw material using THF as a good solvent for the PVDC resin. To make coating solution B.
　工程Ｂ２として、炭化後の膜厚が１００～８５０ｎｍになるようにガラス製離形基板上に塗工液Ｂをスピンコートし、８０℃で熱風乾燥して薄膜状のＰＶＤＣ樹脂膜を得る。 As step B2, the coating liquid B is spin-coated on a glass release substrate so that the film thickness after carbonization becomes 100 to 850 nm, and dried with hot air at 80 ° C. to obtain a thin PVDC resin film.
　工程Ｂ３として、ＰＶＤＣ樹脂膜をアルカリ金属水酸化物ＫＯＨの水溶液と良溶媒ＴＨＦと貧溶媒メタノールとの混合溶液を用いて、脱塩化水素反応処理（脱ＨＣｌ処理）し、ＰＶＤＣ系炭素前駆体膜を得る。 In step B3, the PVDC resin film is subjected to dehydrochlorination reaction treatment (deHCl treatment) using a mixed solution of an alkali metal hydroxide KOH aqueous solution, a good solvent THF, and a poor solvent methanol, and a PVDC carbon precursor film. Get.
　最後に工程Ｂ４として、このＰＶＤＣ系炭素前駆体膜を窒素雰囲気下で６００～３０００℃で緊張加熱炭化を行い、本実施形態のＰＶＤＣ系炭素多孔膜を得ることができる。 Finally, as step B4, this PVDC-based carbon precursor film is subjected to tension heating carbonization at 600 to 3000 ° C. in a nitrogen atmosphere to obtain the PVDC-based carbon porous film of the present embodiment.
　ＰＶＤＣ樹脂は、参考文献Ｇの［００１１］～［００１２］に記載した組成ものを用いることができる。ＰＶＤＣ樹脂中のＶＤＣ成分のモル含有率が高い程、工程Ｂ３の脱ＨＣｌ反応によって、１分子中に発生するポリエン構造が多くなり、複数の分子間での架橋構造が容易に発生し、溶解・溶融することなく固体状態のまま炭化することができるので好ましい。 As the PVDC resin, those described in [0011] to [0012] of Reference G can be used. As the molar content of the VDC component in the PVDC resin is higher, the polyene structure generated in one molecule is increased by the de-HCl reaction in Step B3, and a cross-linked structure between a plurality of molecules is easily generated. This is preferable because it can be carbonized in a solid state without melting.
　しかし、ＶＤＣ組成１００モル％のＰＶＤＣ樹脂は均一に溶解することが難しかったり、そのＰＶＤＣ膜が硬く脆かったりするため、取り扱い難く、塩化ビニリデン共重合体（ＶＤＣ共重合体）が好ましい。ＶＤＣ共重合体中のＶＤＣのモル組成比は、０．６（６０モル％）、好ましくは０．８（８０モル％）以上、より好ましくは０．９（９０モル％）以上であることが好ましい。 However, a PVDC resin having a VDC composition of 100 mol% is difficult to be uniformly dissolved, and the PVDC film is hard and brittle, so that it is difficult to handle, and a vinylidene chloride copolymer (VDC copolymer) is preferable. The molar composition ratio of VDC in the VDC copolymer is 0.6 (60 mol%), preferably 0.8 (80 mol%) or more, more preferably 0.9 (90 mol%) or more. preferable.
　なお、（－ＣＨ２－ＣＨＣｌ－）ｎ、［Ｃｌ含有率５７ｗｔ％］の構造式で与えられる通常のＰＶＣ樹脂に対し、その構造式が［（－ＣＨ２－ＣＨＣｌ－）４－ＣＨＣｌ－ＣＨＣｌ－］ｎ、［Ｃｌ含有率６１ｗｔ％］である塩素化ＰＶＣ樹脂や［（－ＣＨＣｌ－Ｃ（ＣＨ３）Ｃｌ－ＣＨＣｌ－ＣＨＣｌ－）ｎ、［Ｃｌ含有率６８ｗｔ％］である塩素化ゴム等の、塩素含有率（Ｃｌ含有率）が約６０ｗｔ％を超える高塩素化ＰＶＣ樹脂でも、工程Ｂ３において（－ＣＨ２－ＣＣｌ２－）ｎ、［Ｃｌ含有率７３ｗｔ％］であるＰＶＤＣ樹脂と同様に高い架橋構造体が得られ、工程Ｂ４の炭化時でも、溶融することなく炭化することができるため、本実施形態の炭素質原料として用いることができる。 Incidentally, (- CH 2 -CHCl-) n , with respect to conventional PVC resin given by the structural formula [Cl content of 57 wt%], the structural formula [(-CH 2 -CHCl-) 4 -CHCl -CHCl -] N , a chlorinated PVC resin having a [Cl content of 61 wt%], a chlorinated rubber having [(—CHCl—C (CH 3 ) Cl—CHCl—CHCl—) n , and a [Cl content of 68 wt%], etc. Even in a highly chlorinated PVC resin having a chlorine content (Cl content) exceeding about 60 wt%, the same as the PVDC resin having (—CH 2 —CCl 2 —) n and [Cl content 73 wt%] in Step B3 Can be used as a carbonaceous raw material of the present embodiment because it can be carbonized without melting even during carbonization in step B4.
　塗工液Ｂとしては、ラテックスと呼ばれるＰＶＤＣ樹脂の水分散液か、ＰＶＤＣ樹脂を参考文献Ｇの［００１４］中に示されるＴＨＦ、１、４－ジオキサン、シクロヘキサン、シクロペンタノン、クロロベンゼン、ジクロロベンゼン、ＤＭＦ、メチルエチルケトン、エチルアセテート等のＰＶＤＣ樹脂の良溶媒に溶解したＰＶＤＣ樹脂溶液を用いることができる。良溶媒として好ましくはＴＨＦ、ＤＭＦである。 As the coating liquid B, an aqueous dispersion of PVDC resin called latex or THF, 1,4-dioxane, cyclohexane, cyclopentanone, chlorobenzene, dichlorobenzene shown in [0014] of Reference G is used as the PVDC resin. PVDC resin solution dissolved in a good solvent of PVDC resin such as DMF, methyl ethyl ketone, and ethyl acetate can be used. Preferred good solvents are THF and DMF.
　ＰＶＤＣ系炭素前駆体膜は、混合溶液として、参考文献Ｇの［００１４］～［００１５］に示されるアルカリ処理液の組成や処理条件を用いて脱ＨＣｌ処理を、またＰＶＤＣ系炭素多孔膜は、参考文献Ｇの［００１７］に示される炭化条件にて行うことができる。なお、本実施形態のＰＶＤＣ樹脂膜、ＰＶＤＣ系炭素前駆体膜は薄膜であるため、アルカリ（塩基）濃度や良溶媒濃度、脱ＨＣｌ処理温度、更に脱ＨＣｌ処理や炭化処理時間を同特許文献に比べ、低く、短く抑えることができる。 The PVDC-based carbon precursor film is subjected to deHCl treatment using the composition and processing conditions of the alkaline processing liquid shown in [0014] to [0015] of Reference G as a mixed solution, and the PVDC-based carbon porous film is It can be carried out under the carbonization conditions shown in [0017] of Reference G. Since the PVDC resin film and PVDC-based carbon precursor film of this embodiment are thin films, the alkali (base) concentration, good solvent concentration, deHCl treatment temperature, and deHCl treatment and carbonization treatment time are described in the same patent document. In comparison, it can be kept low and short.
　参考文献Ｇ中の図３に、ＰＶＤＣ系炭素多孔膜のＴＥＭ写真が記載されている。同文献の図２は、ＰＶＤＣ系炭素多孔膜の細孔分布のグラフである。同文献の図３より、細孔壁に囲まれた球状の多数の細孔がＰＶＤＣ系炭素多孔膜を形成しており、同文献の図２より炭素多孔膜中にＬ≒１３ｎｍ（α≒１．０）の細孔が多数形成していることが分かる。このように、ハロゲン化ビニリデン系炭素多孔膜は、炭素エアロゲル系炭素多孔膜に比べ、細孔壁厚が厚く強固な炭素多孔膜となる傾向がある。現実の炭素多孔膜は、立方体軸組細孔構造モデルと立方体壁組細孔構造モデルとの中間的な構造を有すると考えられるが、敢えて言えばハロゲン化ビニリデン系炭素多孔膜の細孔構造は、立方体壁組細孔構造モデルに似た構造であることが分かる。 FIG. 3 in Reference G shows a TEM photograph of the PVDC carbon porous membrane. FIG. 2 of the same document is a graph of the pore distribution of the PVDC carbon porous membrane. From FIG. 3 of the same document, a large number of spherical pores surrounded by the pore walls form a PVDC-based carbon porous film. From FIG. 2 of the same document, L≈13 nm (α≈1). It can be seen that a large number of .0) pores are formed. Thus, the vinylidene halide-based carbon porous film tends to be a strong carbon porous film with a thicker pore wall thickness than the carbon airgel-based carbon porous film. An actual carbon porous membrane is considered to have an intermediate structure between a cubic axial structure pore structure model and a cubic wall structure pore structure model, but speakingly, the pore structure of the vinylidene halide carbon porous film is It can be seen that the structure is similar to the cubic wall-set pore structure model.
　参考文献Ｈを活用した方法を以下に述べる。参考文献Ｈには、ＰＶＤＣ樹脂の代わりにフッ化ビニリデン樹脂（ＰＶＤＦ樹脂）フィルムを用いて、有機系強塩基ＤＢＵとＰＶＤＦの良溶媒ＤＭＦとＰＶＤＦの貧溶媒エタノールの混合溶液を用いて、脱フッ化水素処理してＰＶＤＦ系炭素前駆体膜を得た後、炭化処理して多数のメソ孔を有するＰＶＤＦ系炭素多孔膜を得る方法が紹介されており、これも本実施形態の炭素多孔膜として用いることができる。 The method using Reference H is described below. Reference H uses a vinylidene fluoride resin (PVDF resin) film instead of PVDC resin, and a mixed solution of organic strong base DBU, PVDF good solvent DMF, and PVDF poor solvent ethanol. A method for obtaining a PVDF carbon porous film having a large number of mesopores after carbonization treatment after obtaining a PVDF carbon precursor film by hydrogenation treatment has been introduced. Can be used.
　更に、参考文献Ｈには、方法Ａと方法Ｂの折衷的な方法（方法ＡＢ）が紹介されており、この方法も本実施形態に応用することができる。すなわち、図５に示す炭素多孔膜の製造工程のように、工程ＡＢ１として数平均分子量Ｍの異なる塩化ビニル樹脂（ＰＶＣ樹脂）を炭素質原料として用い、ＰＶＣ樹脂粉末をＤＭＦに溶解して、その溶液にＤＢＵを室温で滴下し、ＰＶＣ樹脂の一部を脱ＨＣｌさせて、ＰＶＣ、ＤＭＦ及びＤＢＵの３成分からなる粘凋な塗工液ＡＢを調合する。 Furthermore, in Reference Document H, an eclectic method (Method AB) of Method A and Method B is introduced, and this method can also be applied to this embodiment. That is, like the manufacturing process of the carbon porous membrane shown in FIG. 5, a vinyl chloride resin (PVC resin) having a different number average molecular weight M is used as the carbonaceous raw material as the process AB1, and the PVC resin powder is dissolved in DMF. DBU is dropped into the solution at room temperature, and a part of the PVC resin is deHCled to prepare a viscous coating liquid AB composed of three components of PVC, DMF and DBU.
　続いて、工程ＡＢ２として、塗工液ＡＢを離形フィルムや離形基板上に、炭化後の膜厚が１００ｎｍ～６３μｍになるように塗工・成膜する。この際、離形フィルムや離形基板の周りを取り囲む共に密閉し、塗膜が離形フィルムや離形基板の周囲から流出しないように、且つ溶媒（水）が蒸発して塗工液の組成が変化したり、膜細孔となる領域が潰れたりしないように密封した後、室温～７０℃で順次加熱して十分にゲル化させ、ＰＶＣ系ゲル膜を得る。 Subsequently, as step AB2, the coating liquid AB is applied and formed on the release film or release substrate so that the film thickness after carbonization becomes 100 nm to 63 μm. At this time, the surroundings of the release film and the release substrate are hermetically sealed, the coating film does not flow out of the release film and the release substrate, and the solvent (water) evaporates and the composition of the coating liquid After sealing so as not to change or the region that becomes the membrane pores is not crushed, it is heated at room temperature to 70 ° C. to be sufficiently gelled to obtain a PVC gel membrane.
　工程ＡＢ３として、ＰＶＣ系ゲル膜を離形フィルムや離形基板から剥離した後、ゲル中のＤＭＦを液体ＣＯ２で直接置換した後、ＣＯ２超臨界乾燥を行い、溶媒を飛散して多孔性のＰＶＣ系エアロゲル膜を得る。 As step AB3, after peeling the PVC gel film from the release film or release substrate, the DMF in the gel is directly replaced with liquid CO 2 , and then CO 2 supercritical drying is performed to disperse the solvent and make it porous. A PVC airgel membrane is obtained.
　最後に、工程ＡＢ４として、ＰＶＣ系エアロゲル膜を空気中（Ｏ２下）で１５０～２５０℃で段階的に加熱して熱安定化させるか、ＰＶＣ系ゲル膜をヨウ素（Ｉ２）の蒸気によって１５０～２５０℃で熱安定化させた後、ＰＶＤＣ系炭素多孔膜、ＰＶＤＦ系炭素多孔膜と同様に更に不活性雰囲気下又は窒素雰囲気下で、７００℃～３５００℃（ここでは１０００℃）に加熱炭化してＰＶＣ系炭素エアロゲルによる炭素多孔膜を得ることができる。 Finally, as step AB4, the PVC-based airgel membrane is heat-stabilized by stepwise heating in air (under O 2 ) at 150 to 250 ° C., or the PVC-based gel membrane is heated with iodine (I 2 ) vapor. After heat stabilization at 150 to 250 ° C., heat to 700 ° C. to 3500 ° C. (here 1000 ° C.) in an inert atmosphere or nitrogen atmosphere in the same manner as PVDC carbon porous membrane and PVDF carbon porous membrane. Carbonization can be performed to obtain a porous carbon film made of PVC-based carbon airgel.
　工程ＡＢ４でそのままＰＶＣエアロゲル膜を加熱するとＰＶＣエアロゲル膜が溶融し、その細孔構造が崩れるため、塩素化ＰＶＣ樹脂やＰＶＤＣ樹脂を炭素質原料とした場合と異なり、熱安定化による細孔構造の固定化が必須となる。 If the PVC airgel film is heated as it is in step AB4, the PVC airgel film melts and its pore structure collapses. Therefore, unlike the case where chlorinated PVC resin or PVDC resin is used as a carbonaceous raw material, the pore structure by thermal stabilization Immobilization is essential.
　参考文献Ｈ中の図８にＰＶＣ系炭素エアロゲルの細孔分布が記載されている。図８より細孔分布への分子量Ｍの依存性、ＰＶＣ濃度の依存性が分かる。 FIG. 8 in Reference H shows the pore distribution of the PVC-based carbon airgel. FIG. 8 shows the dependency of the molecular weight M on the pore distribution and the dependency of the PVC concentration.
　以下に、参考文献Ｈに記載された代表的な実験値から、方法ＡＢに従い本実施形態の炭素多孔膜の得たものと仮定したときの、ＰＶＣ、ＤＭＦ、ＤＢＵ３成分からなる溶液中のＰＶＣの重量パーセント濃度（ｗｔ％濃度、［ＰＶＣ］）、ＰＶＣの数平均分子量（Ｍ）、ＰＶＣ分子中の塩素原子（Ｃｌ）に対するＤＢＵ分子のモル比（ＤＢＵ／Ｃｌ）と得られる構造パラメータとの重回帰式、式（４７）、式（４８）を求めた。見かけ密度ρは、
           ρ＝２．１５×１０－１・（［ＰＶＣ］）＋４．６４×１０－２・（Ｍ×１０４）＋５．５２×１０－２・（ＤＢＵ／Ｃｌ）－２．８７×１０－１　…（４７）
           Ｒ＊２＝０．８６
となり、各因子の依存率は、［ＰＶＣ］が６６％、Ｍが２７％、ＤＢＵ／Ｃｌが７％となった。 Below, from typical experimental values described in Reference H, it is assumed that the porous carbon membrane of the present embodiment is obtained according to the method AB, and the PVC in the solution consisting of three components of PVC, DMF, and DBU Weight percent concentration (wt% concentration, [PVC]), number average molecular weight of PVC (M), weight ratio of DBU molecule to chlorine atom (Cl) in PVC molecule (DBU / Cl) The regression equation, equation (47), and equation (48) were obtained. The apparent density ρ is
ρ = 2.15 × 10 −1 · ([PVC]) + 4.64 × 10 −2 · (M × 10 4 ) + 5.52 × 10 −2 · (DBU / Cl) −2.87 × 10 −1 ... (47)
R * 2 = 0.86
Thus, the dependence rates of the factors were 66% for [PVC], 27% for M, and 7% for DBU / Cl.
　また、細孔半径ｒは、
           ｒ＝－４．３１・（［ＰＶＣ］）－１．１２・（Ｍ×１０４）＋１．８３・（ＤＢＵ／Ｃｌ）＋２．７４×１０１　…（４８）
           Ｒ＊２＝０．７４
となり、各因子の依存率は、［ＰＶＣ］が５８％、Ｍが３２％、ＤＢＵ／Ｃｌが１０％となった。なお、細孔半径ｒに対応するαは、式２に従い、ｒを２倍し、λで割ることで得られる。 The pore radius r is
r = −4.31 · ([PVC]) − 1.12 · (M × 10 4 ) + 1.83 · (DBU / Cl) + 2.74 × 10 1 (48)
R * 2 = 0.74
Thus, the dependence rate of each factor was 58% for [PVC], 32% for M, and 10% for DBU / Cl. Α corresponding to the pore radius r is obtained by doubling r and dividing by λ according to Equation 2.
　式（４７）及び式（４８）より、以下のことが分かる。［ＰＶＣ］は、増大するに伴い、見かけ密度ρは大きく、細孔半径ｒに対応するαは小さくなる。一方、Ｍは増大するに伴い、ρは大きく、αは小さくなり、ＤＢＵ／Ｃｌは増大するに伴い、ρ及びαは大きくなる。したがって、大きな細孔を得るためには、［ＰＶＣ］、Ｍはできるだけ小さく、ＤＢＵ／Ｃｌはできるだけ大きくすることが好ましい。 From the equations (47) and (48), the following can be understood. As [PVC] increases, the apparent density ρ increases and α corresponding to the pore radius r decreases. On the other hand, as M increases, ρ increases and α decreases, and as DBU / Cl increases, ρ and α increase. Therefore, in order to obtain large pores, [PVC] and M are preferably as small as possible and DBU / Cl as large as possible.
　更に、第２構造パラメータ群とＴ、Δとの重回帰式、すなわち立方体壁組細孔モデルで近似した場合には、λ＝１３．５ｎｍでは式（３３）、式（３４）を用いて、λ＝６．７５ｎｍでは式（３５）、式（３６）を用いて、立方体軸組細孔モデルで近似した場合には、λ＝１３．５ｎｍでは式（３７）、式（３８）を用いて、λ＝６．７５ｎｍでは式（３９）、式（４０）を用いることで、本実施形態の課題を満たすＴｉ、Δｉ、Ｄｉの組成範囲を知ることができる。 Furthermore, when approximated by a multiple regression equation of the second structural parameter group and T, Δ, that is, a cubic wall set pore model, at λ = 13.5 nm, using Equations (33) and (34), When λ = 6.75 nm is approximated by the cubic axis assembly pore model using Equations (35) and (36), when λ = 13.5 nm, Equations (37) and (38) are used. When λ = 6.75 nm, the composition range of Ti, Δi, and Di that satisfies the problems of the present embodiment can be known by using the equations (39) and (40).
　以上のように、分子構造中に化学反応過程や炭化過程で構造が固定化すると共に気泡が発生する原料を用いて、化学反応や炭化反応をさせ、それらの過程で発生する気泡又は隙間を細孔とすることで、ハロゲン化ビニル樹脂系又はハロゲン化ビニリデン樹脂系炭素多孔膜としての本実施形態の炭素多孔膜を得ることができる。 As described above, a chemical reaction or carbonization reaction is performed using a raw material in which bubbles are generated while the structure is fixed in a chemical reaction process or carbonization process in the molecular structure, and bubbles or gaps generated in those processes are narrowed. By setting it as a hole, the carbon porous film of this embodiment can be obtained as a halogenated vinyl resin-based or halogenated vinylidene resin-based carbon porous film.
２－２－３．補足処理
　図５に示す補足処理として、本実施形態の炭素多孔膜を得た後、炭素多孔膜の表面の片面又は両面に、ＥＵＶの高出力光源からの光による炭素多孔膜の酸化・還元を防止するために、Ｓｉ、ＳｉＣ、ＳｉＯ２、Ｓｉ３Ｎ４、Ｙ、Ｍｏ、Ｒｕ、Ｒｈ等を本実施形態の課題の目標値を満足する範囲内で、公知のスパッタ法、真空蒸着法等の方法で、数ｎｍ被覆することができる。Ｓｉは、ＥＵＶ光の消光係数が低く、屈折率が１．０に近く、更に炭素と反応し炭素膜表面に強度的に優れた数ｎｍのＳｉＣ膜を形成することから特に好ましい。 2-2-3. Supplementary Processing As a supplementary processing shown in FIG. 5, after obtaining the carbon porous membrane of the present embodiment, oxidation or reduction of the carbon porous membrane by light from a high-power EUV light source is applied to one or both surfaces of the surface of the carbon porous membrane. In order to prevent Si, SiC, SiO 2 , Si 3 N 4 , Y, Mo, Ru, Rh, etc. within the range satisfying the target values of the problems of this embodiment, a known sputtering method, vacuum deposition method, etc. By this method, it is possible to coat several nm. Si is particularly preferable because it has a low extinction coefficient of EUV light, a refractive index close to 1.0, and further reacts with carbon to form a SiC film having a few nm with excellent strength on the carbon film surface.
３．本実施形態のペリクル
　図６は、ペリクルを示す斜視図である。図７は、図６におけるＶＩＩ－ＶＩＩ線に沿った断面構成を示す図である。本実施形態のペリクル１０は、図６に示されるように、上述した炭素多孔膜をペリクル膜１として、フレーム３に膜接着剤２を用いて接着したものである。また、ペリクルのマスクとの接着面側には、マスク粘着剤（その保護フィルムも含む）又はフレームとの接合機構４が施されている。 3. Pellicle of this Embodiment FIG. 6 is a perspective view showing a pellicle. FIG. 7 is a diagram showing a cross-sectional configuration along the line VII-VII in FIG. As shown in FIG. 6, the pellicle 10 of the present embodiment is obtained by bonding the above-described carbon porous film to the frame 3 using the film adhesive 2 as the pellicle film 1. Further, a bonding mechanism 4 with a mask adhesive (including its protective film) or a frame is provided on the side of the pellicle that is bonded to the mask.
　本実施形態で用いるフレーム３は、通常のペリクルで用いられている、側面に１個以上の通気孔５が設けられたフレームを用いることができる。フレーム素材としては、好ましくはＺｎとＭｇを添加してアルミ合金の中で最も強度を高めたＡｌ－Ｚｎ系アルミ合金フレーム（７０００系アルミ合金フレーム）がよい。更に好ましくは、ＥＵＶ光がフレームに照射した際の迷光を抑えるため、ＥＵＶ光の屈折率が、真空の屈折率１．０に近く、消光係数ｋも大きい元素ＭｇとＳｉを添加し強度、耐食性を向上させたＡｌ－Ｍｇ－Ｓｉ系アルミ合金フレーム（６０００系アルミ合金フレーム）が良い。或いは、アルミ合金フレームの表面をこれらの元素Ｓｉ、ＳｉＣ、Ｍｇ、Ｚｎで蒸着したフレームを用いることもできる。 As the frame 3 used in the present embodiment, a frame having one or more vent holes 5 provided on the side surface, which is used in a normal pellicle, can be used. The frame material is preferably an Al—Zn-based aluminum alloy frame (7000-based aluminum alloy frame) in which Zn and Mg are added to increase the strength among aluminum alloys. More preferably, in order to suppress stray light when the EUV light is irradiated onto the frame, elements Mg and Si having a refractive index of EUV light close to a vacuum refractive index of 1.0 and a large extinction coefficient k are added to provide strength and corrosion resistance. An Al—Mg—Si-based aluminum alloy frame (6000-based aluminum alloy frame) with improved resistance is preferable. Or the frame which vapor-deposited the surface of the aluminum alloy flame | frame with these elements Si, SiC, Mg, Zn can also be used.
　マスク粘着剤４としては、例えば特開２０１１－１０７４８８公報で紹介されているＡｒＦ用ペリクルに使われている（メタ）アクリル酸アルキルエステルと多官能性エポキシ化合物との反応生成物を含む粘着剤を用いることができる。粘着剤にＥＵＶ光が照射されると粘着剤の成分から分解ガスが発生する可能性があるため、マスクにフレームを接着した場合、フレーム幅の端からマスク粘着剤がはみ出さないように、フレーム３の幅より狭く塗布することができる。また、マスク粘着剤４の配置形態として、一形態としては、図８（ａ）に示すように、フレーム３に設けられた溝６にマスク粘着剤４を配置することができる。このとき、溝６の中において溝６の深さより僅かに厚くマスク粘着剤４を塗布する。また、図８（ｂ）に示すように、マスク粘着剤４が配置される溝６の両側に、マスク粘着剤がフレームの幅からはみ出さないように更に溝７，８を設けてもよい。 As the mask adhesive 4, for example, an adhesive containing a reaction product of a (meth) acrylic acid alkyl ester and a polyfunctional epoxy compound used in an ArF pellicle introduced in JP 2011-107488 A is used. Can be used. When EUV light is applied to the adhesive, decomposition gas may be generated from the components of the adhesive. Therefore, when the frame is bonded to the mask, the frame adhesive should not protrude from the edge of the frame width. It can be applied narrower than the width of 3. Moreover, as an arrangement | positioning form of the mask adhesive 4, as one form, as shown to Fig.8 (a), the mask adhesive 4 can be arrange | positioned to the groove | channel 6 provided in the flame | frame 3. As shown in FIG. At this time, the mask adhesive 4 is applied in the groove 6 slightly thicker than the depth of the groove 6. Further, as shown in FIG. 8B, grooves 7 and 8 may be further provided on both sides of the groove 6 where the mask adhesive 4 is disposed so that the mask adhesive does not protrude from the width of the frame.
　しかし、通常ＥＵＶ用マスクはペリクルを剥離し、再度使用することも多く、その際ＥＵＶ用マスクへのマスク粘着剤の糊残りが問題となることがある。したがって、ペリクル１０とＥＵＶ用マスクとの接合機構として、マスク粘着剤の替わりに、図９に示すように、鉄Ｆｅ、コバルトＣｏ、ニッケルＮｉ等の強磁性体の線芯１１に導電性コイル１２（金属ナノワイヤー、カーボンナノワイヤ等）を巻きつけた電磁石１３をフレーム３の溝６に埋め込み又は粘着剤等を用いて接合し、一方、ＥＵＶ用マスク側にも強磁性体面を設けることで電磁的に接合することがより好ましい。また、フレーム３に電磁石１３を設置する代わりに、ＥＵＶ用マスク側に電磁石を設置し、フレームの溝には強磁性体の線等を設けることもできる。 However, the EUV mask usually peels off the pellicle and is often used again. In this case, the adhesive residue of the mask adhesive on the EUV mask sometimes becomes a problem. Therefore, as a bonding mechanism between the pellicle 10 and the EUV mask, instead of the mask adhesive, as shown in FIG. 9, the conductive coil 12 is attached to the wire core 11 of a ferromagnetic material such as iron Fe, cobalt Co, nickel Ni or the like. Electromagnets 13 wound with metal nanowires, carbon nanowires, etc. are embedded in the grooves 6 of the frame 3 or joined with an adhesive or the like, and on the other hand, a ferromagnetic surface is provided on the EUV mask side as well. It is more preferable to join to. Instead of installing the electromagnet 13 on the frame 3, an electromagnet can be installed on the EUV mask side, and a ferromagnetic wire or the like can be provided in the groove of the frame.
　なお、ゼロ膨張ガラス（ＬＴＥガラス）にＳｉとモリブデン（Ｍｏ）とを交互に４０層対以上蒸着した多層膜で出来たＥＵＶ用マスクへの強磁性体面の設置方法としては、フレームと接着するマスクの領域に予めパーマロイ薄膜やアモルファス希土類鉄系合金膜等の強磁性で構成された枠やシールを貼付したり、これらの強磁性体薄膜を真空蒸着法、スパッタ蒸着、電着法で作製したりしておけばよい。 In addition, as a method of setting a ferromagnetic surface on a mask for EUV made of a multilayer film in which Si and molybdenum (Mo) are alternately deposited on 40 layers of zero expansion glass (LTE glass) alternately, a mask that adheres to a frame is used. A frame or seal made of ferromagnetism such as permalloy thin film or amorphous rare earth iron alloy film in advance is affixed to these areas, or these ferromagnetic thin films are produced by vacuum deposition, sputter deposition, or electrodeposition. You just have to.
　膜接着剤２には、接着力があり且つＥＵＶ光が照射された場合にも分解ガスの発生が少なく、露光に影響を与えない無機系接着剤を用いることが好ましい。例えば、無機物の混ざったエポキシ樹脂系接着剤、例えば藤倉化成株式会社製Ａ－３／Ｃ－３（カーボンブラックをフィラーに使用したエポキシ樹脂系接着剤）、無機物の混ざったフェノール系接着剤、例えば藤倉化成株式会社製ＦＣ－４０３Ｒ・ＸＣ－２２３（黒鉛をフィラーに使用したフェノール樹脂系接着剤）、或いはシリケート系、ホスフェート系、コロイダルシリカ系等の無機物系反応形接着剤を用いることができる。 As the film adhesive 2, it is preferable to use an inorganic adhesive that has adhesive force and generates little decomposition gas even when irradiated with EUV light and does not affect the exposure. For example, an epoxy resin adhesive mixed with an inorganic substance, for example, A-3 / C-3 (epoxy resin adhesive using carbon black as a filler) manufactured by Fujikura Kasei Co., Ltd., a phenolic adhesive mixed with an inorganic substance, for example, FC-403R / XC-223 manufactured by Fujikura Kasei Co., Ltd. (phenolic resin adhesive using graphite as a filler) or inorganic reactive adhesives such as silicate, phosphate, and colloidal silica can be used.
　続いて、ペリクル１０の製造方法について説明する。まず、予め膜接着剤２を塗布したフレーム３と本実施形態のペリクル膜１とを接着した後、マスク粘着剤４を使う場合は、フレーム３のＥＵＶ用マスクとの接着面側にマスク粘着剤４を塗布し、その後、保護フィルムを貼付することで、本実施形態のペリクル１０を得ることができる。 Subsequently, a method for manufacturing the pellicle 10 will be described. First, when the mask adhesive 4 is used after the frame 3 previously coated with the film adhesive 2 and the pellicle film 1 of the present embodiment are bonded, the mask adhesive on the bonding surface side of the frame 3 with the EUV mask is used. The pellicle 10 of this embodiment can be obtained by applying 4 and then attaching a protective film.
　なお、フレーム３のＥＵＶ用マスクとの接合が電磁式等の、粘着剤を使わない場合は、この操作は不要となる。予めフレーム３のＥＵＶ用マスクとの接着面側に電磁石１３等を接着したフレーム３を用いることができる。 Note that this operation is not required when the frame 3 is bonded to the EUV mask such as an electromagnetic type without using an adhesive. It is possible to use the frame 3 in which the electromagnet 13 or the like is bonded to the bonding surface side of the frame 3 with the EUV mask in advance.
　本発明は、リソグラフィマスクを汚染から保護するためのペリクル膜及びペリクルとして、ＥＵＶリソグラフィの分野で好適に利用できる。 The present invention can be suitably used in the field of EUV lithography as a pellicle film and a pellicle for protecting a lithography mask from contamination.
　１…ペリクル膜、３…フレーム、４…マスク粘着剤、１３…電磁石。 1 ... pellicle film, 3 ... frame, 4 ... mask adhesive, 13 ... electromagnet.

Claims (9)

  1. 　炭素多孔体膜で構成されており、膜厚Ｄが１００ｎｍ～６３μｍである、ペリクル膜。 A pellicle membrane made of a porous carbon membrane and having a thickness D of 100 nm to 63 μm
  2. 　１３．５ｎｍの波長の極端紫外光が１回通過する際の透過率Ｔが８４％以上であり、且つ、前記極端紫外光が１回通過する際の前記炭素多孔体膜の細孔による散乱量Δが１０％以下である、請求項１に記載のペリクル膜。 The transmittance T when the extreme ultraviolet light having a wavelength of 13.5 nm passes once is 84% or more, and the amount of scattering by the pores of the carbon porous membrane when the extreme ultraviolet light passes once The pellicle film according to claim 1, wherein Δ is 10% or less.
  3. 　前記炭素多孔体膜の細孔径が、６．７５ｎｍ以上２４３０ｎｍ以下である、請求項１又は２に記載のペリクル膜。 The pellicle membrane according to claim 1 or 2, wherein a pore diameter of the carbon porous membrane is 6.75 nm or more and 2430 nm or less.
  4. 　前記炭素多孔体膜において、質量を体積で割って得られる見かけ密度が１．０×１０－３～２．１ｇ／ｃｍ３である、請求項１～３のいずれか一項に記載のペリクル膜。 The pellicle membrane according to any one of claims 1 to 3, wherein an apparent density obtained by dividing mass by volume in the carbon porous membrane is 1.0 × 10 -3 to 2.1 g / cm 3. .
  5. 　極端紫外光の波長λを１３．５ｎｍ、黒鉛の密度Ｗを２．２５ｇ／ｃｍ３、前記炭素多孔体膜の見かけ密度（ｇ／ｃｍ３）をρ、膜厚（ｎｍ）をＤとしたとき、前記炭素多孔体膜が、以下の各式を満たす構造パラメータを有する、請求項１～４のいずれか一項に記載のペリクル膜。
    α≦３０（α：細孔サイズパラメータ）
    ０．３３５≦Ｎｄ≦１３（Ｎ：膜厚方向への細孔数（個）、ｄ：細孔の壁厚（ｎｍ））
    αλ／ｄ≦８１（λ：露光波長（ｎｍ））
    ただし、Ｎ、ｄは、
    Ｎ＝－１＋｛（Ｗ－ρ）１／３／Ｗ１／３｝＋｛Ｄ（Ｗ－ρ）１／３／αλＷ１／３｝
    ｄ＝－αλ＋｛αλＷ１／３／（Ｗ－ρ）１／３｝     When the wavelength λ of extreme ultraviolet light is 13.5 nm, the density W of graphite is 2.25 g / cm 3 , the apparent density (g / cm 3 ) of the carbon porous film is ρ, and the film thickness (nm) is D The pellicle membrane according to any one of claims 1 to 4, wherein the carbon porous membrane has structural parameters satisfying the following expressions:
    α ≦ 30 (α: pore size parameter)
    0.335 ≦ Nd ≦ 13 (N: number of pores in the film thickness direction (pieces), d: wall thickness of the pores (nm))
    αλ / d ≦ 81 (λ: exposure wavelength (nm))
    However, N and d are
    N = −1 + {(W−ρ) 1/3 / W 1/3 } + {D (W−ρ) 1/3 / αλW 1/3 }
    d = −αλ + {αλW 1/3 / (W−ρ) 1/3 }
  6. 　極端紫外光の波長λを１３．５ｎｍ、黒鉛の密度Ｗを２．２５ｇ／ｃｍ３、前記炭素多孔体膜の見かけ密度（ｇ／ｃｍ３）をρ、膜厚（ｎｍ）をＤとしたとき、前記炭素多孔体膜が、以下の各式を満たす構造パラメータを有する、請求項１～４のいずれか一項記載のペリクル膜。
    α≦３０（α：細孔サイズパラメータ）
    αλ／ｄ≦８１（λ：露光波長（ｎｍ））
    ０．０８ｇ／ｃｍ３≦ρ≦０．７ｇ／ｃｍ３
    Ｄ：１００≦Ｄ≦８５０     When the wavelength λ of extreme ultraviolet light is 13.5 nm, the density W of graphite is 2.25 g / cm 3 , the apparent density (g / cm 3 ) of the carbon porous film is ρ, and the film thickness (nm) is D The pellicle membrane according to any one of claims 1 to 4, wherein the carbon porous membrane has structural parameters satisfying the following expressions:
    α ≦ 30 (α: pore size parameter)
    αλ / d ≦ 81 (λ: exposure wavelength (nm))
    0.08 g / cm 3 ≦ ρ ≦ 0.7 g / cm 3
    D: 100 ≦ D ≦ 850
  7. 　請求項１～請求項６のいずれか一項に記載のペリクル膜と、
    　前記ペリクル膜が貼付されるフレームと、を備えるペリクル。     A pellicle film according to any one of claims 1 to 6,
    A pellicle comprising a frame to which the pellicle film is attached.
  8. 　前記フレームには、前記ペリクル膜が貼付される面とは反対の面に、リソグラフィマスクと接合するためのマスク粘着剤が配設される溝が設けられている、請求項７に記載のペリクル。 The pellicle according to claim 7, wherein the frame is provided with a groove on a surface opposite to a surface to which the pellicle film is attached, in which a mask adhesive for bonding to a lithography mask is disposed.
  9. 　前記フレームには、前記ペリクル膜が支持される面とは反対の面に、リソグラフィマスクと接合するための電磁石が設けられている、請求項７に記載のペリクル。 The pellicle according to claim 7, wherein the frame is provided with an electromagnet for bonding to a lithography mask on a surface opposite to a surface on which the pellicle film is supported.
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