TWI576655B - Film and film for film - Google Patents

Description

Film and film for film protection

The present invention relates to a film for a film for use in photolithography using extreme ultraviolet light and a film comprising the film for film.

The semiconductor integrated circuit began to be produced in the 1960s and sought to improve the total body. From the early 1970s to the recent three years, it has achieved an extremely high integration of about four times the high integration. A technique that contributes to the high integration of the semiconductor integrated circuit is an exposure technique called photolithography. In the exposure technique, the minimum line width of the wiring of the semiconductor integrated circuit depends on the resolution, and the resolution obtained according to the Rayleigh type depends on the opening degree of the exposure optical system, the device constant called the K1 factor of the exposure device, and The exposure wavelength λ (hereinafter also referred to simply as λ). As a result, in order to obtain a resolution of 45 nm or less, it is considered that EUV light lithography using IGBTs having an exposure wavelength of λ=6 to 14 nm (hereinafter also referred to as EUV (Extreme Ultra Violet) light) is referred to as an EUV region. The most powerful.

As a subject of current EUV photolithography development, an output of a light source for EUV, a photoresist for EUV, a defect of a mask for EUV, or a contaminant particle can be cited. Among them, the output of the EUV light source, specifically, the fact that the output of the EUV light source cannot be sufficiently increased seriously affects all problems. For example, in the subject of contaminant particles for a mask for EUV, EUV light is substantially absorbed by a large amount of all substances, and thus the previous exposure wavelength, 436 nm (g line), 365 nm (i line), 248 nm (KrF), The 193 nm (ArF) or the like is different from the reduced projection exposure technique. In the EUV photolithography, the reflection reduction projection exposure technique is used, and the components of all the exposure devices including the EUV mask are placed in a vacuum.

However, according to the recent proof test of EUV light lithography, it is presumed that even if the element is placed in a vacuum, a large amount of contaminant particles are generated in the exposure apparatus, and it is necessary to frequently clean the mask for EUV. Therefore, as long as the output of the EUV light source (intermediate spot value) of several hundred W or more is obtained, a protective film as in the prior art is required.

As a film for a film used for a film for EUV, four types of film structures shown below have been proposed so far. The first film structure is such that an element including a carbon dioxide extinction coefficient k (hereinafter also referred to as k) is low, for example, a carbon nanotube (CNT Nano Tube: CNT) is equal to a column surface of the EUV mask. The interval of ten nm and the height of several μm are grown (for example, refer to Patent Document 1).

In the second film structure, 矽Si is used as an ultrathin flat film having a thickness of 20 to 150 nm for a lower element of EUV light of λ = 13.5 nm, and this is used as a film for a protective film for EUV (for example, see Patent Literature) 2).

The third film structure uses an element having a lower k for EUV light (yttrium (Si), yttrium (Ru), yttrium (Ir), gold (Au), yttrium (Rh), carbon (C), etc.) or a compound ( Aluminum nitride (AlN), tantalum nitride (SiN), tantalum carbide (SiC), etc., a single layer or a plurality of flat films having a thickness of 30 to 300 nm, and an opening having a rectangular shape, a honeycomb shape, and the like A composite film called a so-called grid or a mesh film (hereinafter also referred to as a support film) having a period of several tens of μm and a line and a line length of several hundred μm to several mm (For example, refer to Patent Documents 3 to 5 and Non-Patent Document 2).

In the fourth film structure, an aerogel film made of an element (Si, Ru, C, or the like) having a low E light of EUV is used as a film for a protective film for EUV. The aerogel film refers to a sponge-like porous film having a plurality of micropores, mesopores, and macropores containing up to 90.0 to 99.8% of air and an apparent density of 10 ^-3 to 10 ^-1 g/cm ³ . The industry believes that by using an aerogel film that minimizes the wavelength of the EUV light in the aerogel film and minimizes the decrease in transmittance caused by Rayleigh scattering, even if the film thickness is about 1.0. The support film of ~10.0 μm also has a film strength and a film having a high transmittance with respect to EUV light (see, for example, Patent Documents 6 and 7).

The film structure is focused on the following conditions: (1) The absorption of the substance in the EUV region is heavily dependent on the type of the element of the substance and the density of the substance; (2) the foaming can be achieved by allowing Rayleigh scattering. The bulk structure (porous membrane) ensures the film thickness and increases the film strength. In particular, in Patent Document 6, it is considered that EUV having a high EUV light transmittance is obtained by using a helium gel (Si aerogel) prepared by electrochemically dissolving Si with a solution containing hydrogen fluoride HF as a main component. A film for a protective film, which is obtained by a metal foaming aerogel having a high oxidation resistance, which is a film containing a noble metal or A hydrogel of a transition metal ion such as Ru is irradiated to form a metal nanoparticle.

Further, Patent Document 7 shows an attempt to realize the film structure by CNT. This structure uses a method of producing a film having a thickness of 1.0 to 5.0 nm by using the CNT itself and using it as a film for a protective film for EUV. It is considered that an aerogel-like film structure can be obtained by setting the apparent density of the CNT film to 1.5 × 10 ^-3 to 0.5 g/cm ³ .

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] US Patent No. 7763394

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2009-271262

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2005-43895

[Patent Document 4] US Patent No. 7153615

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2010-256434

[Patent Document 6] Japanese Patent Laid-Open Publication No. 2010-509774

[Patent Document 7] US Patent No. 7767985

[Non-patent literature]

[Non-Patent Document 1] B. L. Henke, E. M. Gullikson and J. C. Davis, X-ray interactions: photoabsorption, scattering, transmission and Reflection at E=50~30000 eV, Z=1~92, Atomic Data and Nuclear Data Tables Vol. 54 (No. 2), 181 - 342 (July 1993)

[Non-Patent Document 2] Y. A. Shroff et al. "EUV pellicle Development for Mask Defect Control", Emerging Lithographic Technologies X, Proc. of SPIE Vol. 6151, 615104 (2006)

However, in the first film structure, although the carbon C is used as an element having a low extinction coefficient k, the dustproof protective film directly contacts the surface of the mask for EUV, and the mask surface overlaps with the focus of a portion of the film for the protective film. There is a possibility that the performance as a protective film cannot be exerted. Moreover, the structure control of CNT is extremely difficult and the manufacturing cost becomes high. Therefore, the first film structure is not realistic.

In the second film structure, even if Si having a low k is used, it is necessary to set the thickness of the film to 200 nm or less in order to ensure the transmittance of 50% or more of EUV light passing through the film for the secondary film. 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 a film for a film is formed by using Si, if the film for a film is damaged by impact or the like, the film may be adhered to the surface of the mask for EUV. In this case, there is a problem that it becomes a contaminant particle which does not function as a film for a film and is difficult to remove.

The third film structure is configured to ensure the film strength, and the film thickness can be made thin. However, the support film itself functions as an obstacle or a field of view 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% as compared with the transmittance of the flat film alone. . Further, when a material other than the carbon C is used as a material for the film for a film, the problem of the contaminant particles is generated at the time of breakage.

The fourth film structure not only ensures high permeability with respect to EUV light, but also has superiority to the second film structure and the third film structure in terms of greatly improving the film thickness. However, the film for an EUV film shown in Patent Document 6 has the following various problems. That is, with the third In the case where the film structure of the film for EUV is used as a film for a film for EUV, the film for EUV film is damaged by any cause such as impact, and it becomes a pollution which is difficult to remove. The problem of particles.

Further, when the CNT film shown in Patent Document 7 is used as an aerogel film, the following problems also occur. Even if an aerogel film having a film thickness of 1 to 2 nm and a fiber length of 10 μm is formed to have an extremely thin film thickness of 1.0 to 5.0 nm, 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 by about 1.5 g/cm ³ of the usual carbon density, a high transmittance obtained by using the original aerogel film cannot be obtained.

Further, in general, CNTs use a large amount of metal catalysts such as iron Fe, cobalt Co, and nickel Ni having a high extinction coefficient in the production process, and therefore, they inevitably contain a large amount of impurities, and if used directly, they become carbon films having a large extinction coefficient. Unable to achieve a high transmission rate. Further, in order to provide only a carbon film having a low extinction coefficient, when the above impurities are removed, there is a problem that productivity is lowered and manufacturing cost is extremely high.

An object of the present invention is to provide a film for a film and a film which have high permeability to EUV light, have practically sufficient physical strength and durability, and can easily remove film fragments and have excellent productivity.

In order to solve the above problems, the present inventors have conducted intensive studies, and as a result, it has been found that the raw material of the film for a film is made of a common carbon, and the following porous film can be provided with good productivity and at low cost: even if one part of the film When it is damaged and adhered to the surface of the mask for EUV, it can be easily removed, and has a pore size/aperture distribution and an apparent density which can be used for the film, thereby solving the above problems.

In other words, the film for a film of one aspect of the present invention is composed of a carbon porous film, and has a film thickness D of 100 nm to 63 μm.

In one embodiment, the transmittance T of the extreme ultraviolet light having a wavelength of 13.5 nm passes through one time. When the amount of the extreme ultraviolet light is one, the amount of scattering Δ caused by the pores of the carbon porous film may be 10% or less.

In one embodiment, the apparent density obtained by dividing the mass by the volume in the carbon porous film may be 1.0 × 10 ^-3 to 2.1 g/cm ³ .

In one embodiment, the wavelength λ of the extreme ultraviolet light is 13.5 nm, the density W of the graphite is 2.25 g/cm ³ , and the apparent density (g/cm ³ ) of the carbon porous film is ρ. When the film thickness is D (nm), the carbon porous film may have structural parameters satisfying the following formulas (1) to (5), α ≦ 30 (α: pore size parameter) (1)

0.335≦Nd≦13 (N: the number of pores in the film thickness direction (number), d: the wall thickness of the pores (nm)) (2)

Λλ/d≦81 (λ: exposure wavelength (nm)) (3)

Wherein, N and d are N=-1+{(W-ρ) ^1/3 /W ^1/3 }+{D(W-ρ) ^1/3 /αλW ^1/3 } (D: film thickness ( Nm))(4)

d=-αλ+{αλW ^1/3 /(W-ρ) ^1/3 } (5).

In one embodiment, the wavelength λ of the extreme ultraviolet light is 13.5 nm, the density W of the graphite is 2.25 g/cm ³ , and the apparent density (g/cm ³ ) of the carbon porous film is ρ. When the film thickness (nm) is D, the carbon porous film may have structural parameters satisfying the following formulas (6) to (9), and α≦30 (α: pore size parameter) (6)

Λλ/d≦81 (λ: exposure wavelength (nm)) (7)

0.08g/cm ³ ≦ρ≦0.7g/cm ³ (8)

D: 100≦D≦850 (9).

A protective film according to another aspect of the present invention includes the above-mentioned film for a protective film and a frame to which a film for a protective film is attached.

In one embodiment, a groove having a mask adhesive for bonding to the photolithography mask may be provided on a surface opposite to the surface on which the film for the film is attached.

In one embodiment, an electromagnet for bonding to the photolithography mask may be provided on a surface opposite to the surface of the film for supporting the film.

According to the present invention, it is possible to produce a high permeability to EUV light, to have practically sufficient physical strength and durability, and to easily remove film fragments, and to have excellent productivity.

1‧‧ ‧ film for film

2‧‧‧membrane adhesive

3‧‧‧Frame

4‧‧‧ mask adhesive

5‧‧‧vents

6‧‧‧ slots

7, 8‧‧‧ slots

10‧‧‧Shield

11‧‧‧core

12‧‧‧ Conductive coil

13‧‧‧Electromagnet

Fig. 1(a) is a graph showing the relationship between the extinction coefficient and the transmittance and the reflectance, and (b) is a graph showing the relationship between the refractive index and the transmittance and the reflectance.

Fig. 2 is a graph showing the relationship between the wavelength and the refractive index and the extinction coefficient.

Fig. 3 is a graph showing the relationship between apparent density and refractive index and extinction coefficient.

Fig. 4 is a schematic view showing a structural model of a carbon porous body film.

Fig. 5 is a view showing a manufacturing step of a carbon porous body film.

Fig. 6 is a perspective view showing a protective film of an embodiment.

Fig. 7 is a view showing a configuration of a cross section taken along line XII-XII of Fig. 6.

8(a) and 8(b) are views showing a cross-sectional structure of the frame.

9(a) and 9(b) are views showing a cross-sectional structure of the frame.

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 components are denoted by the same reference numerals, and the repeated description is omitted.

In the following description, "1. Definition or description of the terms used in the present embodiment" will be described below. "2. Film for protective film of the present embodiment", "3. Protective film of the present embodiment" The order of the details will be specifically described.

1. Definition or description of terms used in this embodiment [Default value of this embodiment]

The reference value of the present embodiment is a value indicating three kinds of physical property values of the transmittance, the scattering amount, and the film thickness of the film for a film which is preferable in the problem of the present embodiment.

The value of the transmittance T of the film for a film (hereinafter also referred to as T, the unit is %) is preferably 70% or more of the reflectance of one mirror used in the EUV photolithography, and is set as a reference value of T. . In the case of exposure, the EUV (Extreme Ultra Violet) light is incident on the mask surface of the EUV at an incident angle of θ=6°, and passes through the film for covering the mask surface of the EUV mask twice. Therefore, in the case of passing the film for a film for one time, T is preferably 84% or more (because it is 84% × 84% = 70% when passed twice). In the same manner, in order to obtain 80% or more and 90% or more of T when the second pass is obtained, the T required for the first pass is 89% or more and 95% or more, respectively. Hereinafter, the reference value of the T is referred to as a "transmittance reference value", and the reference values of 84%, 89%, and 95% are referred to as a first transmittance standard (T1) and a second transmittance standard (T2), respectively. Third transmittance benchmark (T3).

Since the film for the film is a porous film, the amount of scattering generated (hereinafter also referred to as Δ, the unit is %), if the value is large, not only T is small but also occurs on the surface of the EUV mask during exposure. The circuit image is blurred. Therefore, it is expected that the value of the amount of scattering is as small as possible, and there is no clear reference value. In the present embodiment, the upper limit of the range value scattering amount which is considered to be preferable when the film for the first time film is used is referred to as the "scattering amount reference value", and the reference values of 10%, 5%, and 1% are respectively referred to as The first scattering amount reference (Δ1), the second scattering amount reference (Δ2), and the third scattering amount reference (Δ3) are used. In the case of the amount of scattering, the inventors of the present invention considered that the amount of scattering when the membrane for covering the mask for EUV is covered twice is twice as large as the amount of scattering when passing through the first time.

The film thickness of the film for a film (hereinafter also referred to as D, the unit is nm) greatly affects the film strength (bending rigidity of the film) and the ease of use of the film. In order to obtain a film for a film of a flat film of the Si element, it is necessary to obtain D of 50 to 100 nm in order to obtain a T of 70% or more when passing through the film for the film twice. By using a carbon porous film as in the present embodiment, it is possible to protect Thicken D by maintaining the transmittance. Therefore, D = 100 nm or more is set as the minimum necessary film thickness of this embodiment. The film thickness D is preferably 300 nm or more, more preferably 500 nm or more. Hereinafter, the reference value of D is referred to as a "film thickness reference value", and the reference of 100 nm, 300 nm, and 500 nm is referred to as a first film thickness reference (D1), a second film thickness reference (D2), and a third film thickness, respectively. Benchmark (D3).

[Structure model of film for protective film of the present embodiment]

The film for a film of the present embodiment is composed of a carbon porous film, and the film thickness D of the film for a film is 100 nm to 63 μm. Further, the film for a protective film of the present embodiment preferably has the following specific structure. Hereinafter, a structure model for specifying a film for a film, a structural model of the carbon porous film, and each structural parameter will be described.

(Premise 1)

The realistic carbon porous film is not formed by monodispersion of fine pores (a pore size, a wall thickness, a column thickness, a shape, and the like, and a uniform structural model of various pores), and various pores are adopted. A mixture of mixed structures. However, in the present embodiment, in order to simplify the discussion, the carbon porous film obtained in reality is similar to the carbon porous film including the monodisperse cubic shell-shaped or cubic-frame-shaped pores described below (hereinafter, each of them is called It is a cubic wall group pore model, a cubic shaft group pore model, and its structure can be specified by structural parameters.

(Premise 2)

The density W of the graphite (gC) and the density of the amorphous carbon (aC) at room temperature are respectively W of 2.25 to 2.26 g/cm ³ (in the present embodiment, W = 2.25 g/cm ³ ) The density of aC is 1.8~2.1g/cm ³ . Therefore, the actual carbon density takes a value in the range of 1.8 to 2.26 g/cm ³ depending on the crystallinity thereof.

In this way, not all of the pores of the pores or the pillars of the carbon porous membrane constituting the actual carbon are formed of crystals of graphite. In the present embodiment, the polycrystals formed by the aggregation of the crystallites of graphite in an unaligned manner are formed. The crystallinity of carbon is relatively low. If the density is less than 2.25 g/cm ³ , the wall thickness or column thickness d may be increased according to the optical constant (especially k) of carbon at the density as described in the following [Additional Note]. Substantial wall thickness dN or column thickness dN ^1/2 .

Based on (premise 1) and (premise 2), as the pore structure model of the carbon porous film of the present embodiment, a cubic shell or cube having a wall thickness or a column thickness d and a length L0 on one side is considered. The frame-shaped pores (pore size L) are formed by stacking N in the thickness direction, and are sequentially referred to as a cubic wall group pore model and a cubic axis group pore model. Furthermore, the layers covered with the cube are offset and stacked in the thickness direction in such a manner that the apexes of the four corners of each cube in the thickness direction are located at the center of the face of the adjacent cube. By assuming a pore structure model, the relationship between each of the L, L0, and d is between the film thickness D, the number of layers N of the pores, and the pore size parameters α and d.

L0=L+d (10)

D=Nαλ+(N+1)d (11)

Further, the structure of the porous film of the present embodiment can be defined by using the first and second structural parameters described below, and the relationship between the formulas (12) and (14) is established between the respective structural parameters regarding the cubic wall group pore model. Regarding the cubic axis group pore model, the relationship of the formulas (15) to (17) holds.

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)

For the cubic wall group pore model, Equations (11) and (14) use the first structural parameter group to indicate the second structural parameter group, and Equations (12) and (13) use the second structural parameter group to indicate 1 structural parameter group.

Regarding the cubic axis group pore model, Equations (11) and (17) use the first structural parameter group to indicate the second structural parameter group, and Equations (15) and (16) use the second structural parameter group to indicate 1 structural parameter group.

[structural parameter group]

The preferred structure of the carbon porous film in the present embodiment depends on the following three physical property values, the respective reference values of T, Δ, and D. Further, the carbon porous film has a structure in which the pore diameter (L) or the pore size parameter (α), the wall thickness of the pores or the column thickness (d), and the number of layers of the pores in the film thickness direction (N) Further, as the first structural parameter group, the apparent density of L (or α), D, and the carbon porous film described as ρ (ap) or ρ is used as the second structural parameter group, and can be specified by using these structural parameters. . The first structural parameter group is a microscopic structural parameter, and is suitable for the structure of the carbon porous membrane. However, it is difficult to directly and indirectly measure and observe, and it is difficult to use the equivalent value control and the structure of the predetermined membrane in the manufacturing process. The second structural parameter group is a macroscopic structural parameter, and it is relatively easy to directly and indirectly measure and observe, and it is easy to control the structure by using the equivalent value in the manufacturing process, and the pore structure model is not assumed based on the equivalent value, and the microstructure cannot be uniquely determined.

Between the structural parameter groups of the two, if the structural model of the carbon porous membrane is assumed, the equations (12) to (14) are established in the cubic wall group pore model, and the equation is in the cubic axis group pore model. The specific relationship of the formula (17) is established, but the strict correspondence cannot be obtained frequently.

In the present embodiment, the content is described by using two structural parameter groups as appropriate. When there is a contradiction between the two, in the range where the reference value is satisfied, in reality, the second structural parameter that easily defines the structure of the carbon porous film is preferentially used. group.

[Aperture L, pore radius r]

The so-called pore size (L), the adsorption isotherm according to the gas adsorption type pore distribution measurement method The peak pore radius r (peak) and the maximum peak radius r (max) of the pore distribution curve (at the intersection of the peak of the pore distribution and the reference of the pore distribution, the pore radius of the larger side) The value of the value is twice the value (referred to as the double value), and is set to L (peak) and L (max), and the unit is set to [nm]. Furthermore, r(max) and L(max) are used to discuss the upper limit of each reference of △, and in other cases, L(peak) is used as L, and r(peak) is used unless otherwise specified. As r. In terms of experiments and experience, r(max) is as shown in Fig. 6 and Fig. 8 of Lin Shunyi, Luhe Junying, Carbon, No. 236, 15-21 (2009) [hereinafter referred to as Reference A]. In the logarithmic scale of r, the horizontal axis of the pore distribution map is set, and the vertical axis is set as the pore distribution curve of dV/d[Log(r)] of the integrated pore volume, and in most cases, it is roughly r(peak). 1.5 to 3 times or so. Further, when the peak of the pore distribution is low and it is difficult to understand r(max), r(peak) is set as a substitute value of r(max).

In the gas adsorption type pore distribution measurement, the usual carbide sample is heated under vacuum at 200 to 250 ° C for 2 to 15 hours, and then subjected to nitrogen adsorption and desorption isotherm measurement at a liquid nitrogen temperature, according to the adsorption. The isotherm is obtained by DH analysis or BJH analysis with an isotherm. In the present embodiment, this method is used to obtain the aperture.

[Pore size parameter α]

The pore size parameter (α) is obtained by using α=L/λ (18) when the aperture is set to L and the wavelength of the EUV light used for exposure is λ.

The value defined refers to the use of the aperture relative to λ to represent the aperture. Furthermore, α in the present application becomes 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.

Furthermore, in the cubic wall group pore model, each pore is divided by a wall, so that the pore diameter can be substantially defined. In the cubic axis group pore model, values for distinguishing the pores and distinguishing them formally (imaginary) as shown in Fig. 4(b).

[Thick wall thickness or column thickness d]

The thickness of the pores or the thickness of the column (d) in the present embodiment means the average thickness of the carbon walls of the pores constituting the carbon porous film (the barriers to be pores) in the pore wall model of the cubic wall group. , the thickness of the wall of the cube wall group. In the cubic axis group pore model, the average thickness of the carbon rod (column) which constitutes the pores and pores constituting the carbon porous membrane is the thickness of the cube frame. The unit is set to [nm].

d A cross-sectional photograph of the porous film can be taken by a transmission electron microscope (TEM) or a scanning electron microscope (SEM), and image processing can be performed. However, the observation at high magnification is extremely difficult in itself, and the information obtained from the cross-sectional photograph itself is local, and it is uncertain whether it is the average wall thickness of the porous membrane. Therefore, in the present embodiment, it will be borrowed from the cubic wall group pore model. The value calculated from the equation (13) from α and ρ(ap) is d, and the value calculated from α and ρ(ap) by the equation (16) in the cubic axis group pore model is d.

Regarding the value of d, considering that the size of the carbon atom is about 0.33 nm and the interlayer distance of graphite (considered as a laminate of graphene sheets) is 0.335 nm, the thickness of one sheet of graphene sheet is about 0.335 nm. lower limit. However, in the case of one or two layers (d = about 0.67 nm) of graphene sheets, when a large pore diameter (for example, α>4) or a large force is applied to the film for a film, etc., the wall The strength or the column strength (bending rigidity of the film) is insufficient, so in reality, it is preferable that the graphene sheet has 4 layers (d = about 1.35 nm) or more. Of course, d can be brought close to 0.335 nm in the case where the aperture is small (for example, α < 1) or when a large force is not applied to the film.

[Number of layers of pores N]

The number of layers (N) of the pores refers to the number of layers of the pores of the pore diameter L in the film thickness direction. In the present embodiment, the value calculated by the equation (12) based on α, ρ(ap), and D is N in the cubic wall group pore model, and is used in the cubic axis group pore model. (15) The value calculated based on α, ρ(ap), and D is set to N. N shall be an integer of N≧1 in the definition of language, and may also allow positive real values. The present inventors considered that the mantissa portion of the numerical value below the decimal point is a deviation reflecting the pore structure model in which the pores of the monodisperse cubic shell shape or the cubic frame shape are neatly stacked.

[visual density ρ (ap), arithmetic apparent density ρ]

The apparent density ρ(ap) is the density of the film volume when no pores are formed inside the porous film, and is the ratio of the volume V of the film and the mass G of the film determined by the film outside the film. The value calculated in the form of V. On the other hand, the arithmetic apparent density ρ is based on the pore structure model. In the present embodiment, if it is a cubic wall group pore model, it will be based on α, ρ(ap), D by the formula (14). The calculated value is ρ, and if it is a cubic axis group pore model, the value calculated from α, ρ(ap), and D by the equation (17) is ρ. Due to assumptions (premise 1) and (premise 2), the following uses ρ(ap)=ρ in the form of no distinction between the two. The unit is set to [g/cm ³ ].

[film thickness D]

The film thickness (D) refers to the thickness of a sheet, a film, or a film used in the usual sense. The measurement of the thickness of the present embodiment can be carried out by using an electron microscope (SEM) to photograph the porous film at intervals of 1 mm or more at intervals of 1 mm or more, and to obtain a value obtained by averaging the dimensions. The unit usually uses [nm] and [μm] is used as needed.

[Pin shape]

The average pore shape of the porous film is as described in Reference A, Matsuoka Hideki, Crystallography Society, No. 41, 213-226 (1999), Nishikawa Keiko, Carbon, No. 191, 71-76 (2000). It is obtained from the analysis of the scattering intensity in the Debye-Porod region of the small-angle X-ray scattering (SAXS). That is, when the double logarithmic graph is plotted on the X-ray scattering intensity I as a function of the scattering vector s, if the slope of the straight line is -4, -2, -1, the shape of the pores is spherical or disc, respectively. Shaped, cylindrical.

2. Film for protective film of the present embodiment and method for producing the same

2-1. The film of this embodiment

Each of the [technical points] will be described in detail below with respect to the film for a film of the present embodiment.

[Technical Point 1]

Technical Point 1 The film for the film is a porous film. In the scattering theory of Mie (Mie scattering itself is caused by scattering by spherical particles, qualitatively regardless of shape), the scattering of light by spherical particles (spherical pores), the diameter of particles (fine pores) (Aperture) is set to 2γ, the wavelength of incident light is λ, and when the particle size size parameter Λ(=2πγ/λ) is used, when Λ is sufficiently smaller than 1 (Λ<<1), it occurs. Rayleigh scattering occurs when the Λ is approximately 1 (Λ≒1), and geometric scattering occurs when Λ is sufficiently large compared to 1 (Λ>>1). Therefore, the present inventors have considered that, in the case of a porous body (porous film) having a pore diameter of Λ≧1, when light is incident upon exposure, light is scattered at the interface of the pore walls or the column and the pore portion, and not only is not obtained. The transmittance is sufficient, and the circuit image of the mask cannot be accurately imaged on the wafer (see Patent Document 6 and Patent Document 7).

However, it is understood that even in the case of a porous body (porous film) having a pore diameter of Λ≧1 or more, the refractive index of the pore wall or the column is equal to the refractive index of the pore portion, that is, the vacuum of 1.0, or the refractive index of the pore wall or column. When the difference Δn between the refractive indices of the pores (the space in the pores) is close to 0, for example, when Δn = 0.04 or less, since the interface between the pore walls and the pore portions cannot be recognized, the light is hardly reflected. , scattering and straightforward.

1 shows an optical constant of a flat film (non-porous film) showing a value of assuming optical constant (refractive index n, extinction coefficient k) and a film thickness D, and a transmittance T and a reflectance at an incident angle θ=6°. A graph of the relationship of R. The graph shown in Fig. 1 was calculated using the "G-Solver lattice analysis software tool (G-Solver)" commercially available from "Grating Solver Development Company". Fig. 1(a) is a graph showing the dependence of T and R on the flat film of D = 100 nm and n = 1.0 with respect to k, and Fig. 1 (b) shows the flat film T of D = 100 nm and k = 0.0005. And a plot of the dependence of R on n. In Fig. 1(a), the area enclosed by the broken line indicates the area where k of 84% of T≧ can be secured. According to Fig. 1(a), T changes greatly due to a slight change in k. When the film thickness is about 100 nm in the non-porous film, k must be at least 10 ^-3 or less to obtain T≧. T1 = 84%.

Further, in Fig. 1(b), a region surrounded by a broken line indicates a region where the reflectance is suppressed to n of R ≦ 0.2%. As can be seen from Fig. 1(b), as described above, when n = 0.94 to 1.4, that is, Δn ≦ 0.04, reflection from the interface can be suppressed, and T becomes maximum.

The first advantage of using a porous film as a film for a protective film is to substantially alleviate the thickness limitation of a film of 50 to 100 nm in the conventional Si single crystal flat film. As described below, T is T1 or more and Δ is Δ1 or less, and D is 100 nm. The above (D1 or more) may be 300 nm or more (D2 or more) or 500 nm or more (D3 or more).

The second advantage of using a porous film as a film for a film is that a porous film such as a corrugated board called corrugated paper has a higher bending rigidity than a flat film paper of the same weight, and a porous film The bending rigidity becomes larger than that of the flat film (non-porous film) of the same weight.

The corrugated cardboard is a porous structure having a hole in which one end of the suction tube is extended. On the other hand, the porous film of the present embodiment has a three-dimensional porous structure, so that stress concentration is more likely to occur, and the bending rigidity of the film is further Higher. As a result, when the porous film of the present embodiment is used as the film for a protective film, the film is bent by its own weight to a level smaller than that of the other materials of the same area and the same weight.

[Technical Point 2]

The technical point 2 is that the porous film is composed of carbon. The first advantage of using a carbon to form a porous film is the superiority of the porous filmed carbon as an optical constant. The density is determined by the ratio of the type of the element constituting the film to the crystal structure of the film and the amorphous structure. The optical constants n and k in the EUV region can be obtained from Non-Patent Document 1 described above. In fact, in order to calculate a specific value, a web page of CXRO (The Center for X-ray Optics) is <http://henke.lbl.gov/optical_constants/getdb2.html>.

Regarding n and k obtained by using the apparent density ρ of the porous film which is smaller than the density of the non-porous body (generally referred to simply as density and true density) as the density, it is assumed that the crystal structure and the amorphous structure are unchanged from each other. Then, the value can be regarded as the optical constant of the porous film having the ρ. Here, a flat film (non-porous film) having an apparent density ρ and an optical constant of the ρ is referred to as a porous In place of the flat film, for the sake of convenience, it is possible to obtain n and k of a porous film having various ρ in place of the flat film, regardless of the scattering by the pores, for the sake of convenience.

2 shows carbon C (density 2.2 g/cm ³ ), 矽Si (density 2.33 g/cm ³ ), lanthanum carbide SiC (density 3.2 g/cm ³ ), and apparent density ρ=0.6 g/cm ³ of C. A plot of the dependence of n and k with respect to wavelength λ. As shown in FIG. 2, the optical constants of Si and SiC are discontinuously changed by the L absorption end of Si in the vicinity of λ=12 nm, whereas the optical constant of C is continuous, n monotonously increases, and k monotonously decreases. In particular, at λ ≦ 12 nm, k becomes C (ρ = 0.6 g / cm ³ ) which is smaller than the values of Si and SiC.

Figure 3 is a graph showing the optical constants n, k at λ = 13.6 nm and λ = 6.7 nm for Si, SiC, and various apparent densities ρ, the optical constants of the EUV region and the wavelengths and substances of the light used. The density is related to, for example, a wavelength range of λ = 6.7 to 13.6 nm, and in the case of Si (2.33 g/cm ³ ), k is 9.5 × 10 ^-3 (λ = 6.7 nm) to 1.8 × 10 ^{-3 .} (λ = 13.6 nm) and n is 0.99 (λ = 6.7 nm) to 1.0 (λ = 13.6 nm). On the other hand, in the case of carbon, if it is graphite (2.25 g/cm ³ ), k is 7.6 × 10 ^-4 (λ = 6.7 nm) ~ 7.2 × 10 ^-3 (λ = 13.6 nm), and n is 0.99 (λ = 6.7 nm - 0.96 (λ = 13.6 nm).

In this case, if it is a region of λ=13.6 nm, Si is more suitable than graphite for producing a film for a film, and if it is a region of λ=6.7 nm, it is better than graphite.

Further, when carbon is formed into a porous film as in the present embodiment, if C is ρ = 0.6 g/cm ³ , k is 2.0 × 10 ^-4 (λ = 6.7 nm) to 1.9 × 10 ^-3 ( λ = 13.6 nm), n is 1.0 to 0.99. If C is ρ = 0.4 g/cm ³ , then k is 1.4 × 10 ^-4 (λ = 6.7 nm) ~ 1.3 × 10 ^-3 (λ = 13.6 nm), and n is 1.0 (λ = 6.7 nm) to 0.99. (λ = 13.6 nm). If C is ρ = 0.2 g/cm ³ , then k is 6.8 × 10 ^-5 (λ = 6.7 nm) ~ 6.4 × 10 ^-4 (λ = 13.6 nm), and n is 1.0 (λ = 6.7 nm) - 1.0 (λ = 13.6 nm). If C is ρ=0.08g/cm ³ , then k is 2.7×10 ^-5 (λ=6.7nm)~2.6×10 ^-4 (λ=13.6nm), and n is 1.0 (λ=6.7nm)~1.0. (λ = 13.6 nm).

Thus, carbon is made into a porous film and reduces the apparent density, not only λ = 6.7 nm. The region also has a lower k equal to or higher than Si and a n close to 1.0 in the region of λ=13.6 nm.

A second advantage of using a carbon to form a porous film is that it can be easily removed even if the film for a protective film is damaged and adhered to the mask. For example, such as Takagi Kumaki, Ritsumeikan University Research Report, S22-03, "Carbon Stacking Experiment on EUV Photolithography Mask: Evaluation of Cleaning Technology", Laoquan Bozhao, Graduate School of Engineering, Kyushu Institute of Technology The carbon attached to the EUV mask can be removed by the following reaction as described in the Ph.D. thesis "Using Ultraviolet (EUV) Photolithography Basic Technology" (March 19): VUV light (λ = 172 nm) and EUV light (λ = 13.5 nm) which are directly decomposed by organic molecules can be oxidized by active oxygen to form carbon monoxide CO or carbon dioxide CO ₂ (oxidation method), using atomic hydrogen The reaction is reduced to a methane hydrocarbon (CH _X ) (reduction method).

A third advantage of producing a porous film using carbon is that it is easy to produce a porous film having a target pore diameter and a film thickness by applying a conventional method for producing a carbon porous film. In other words, as described in "2.2 Method for Producing Film for Films of the Present Embodiment", a film formed by using a sol-gel-transformed organic compound is used to form a film, and a large amount of solvent-containing water is formed by a sol-gel method. In the state of the gel, the solvent is dried and removed in such a manner that the structure does not disintegrate, whereby an aerogel film which is a porous body containing a large amount of bubbles is obtained. Further, a method of finally carbonizing an aerogel film to obtain a carbon porous film as a carbon aerogel, or a polymer used for immobilizing a structure and generating bubbles by a chemical reaction process or a carbonization process in a molecular structure may be mentioned. a method in which a polymer solution of a raw material (which is an organic compound) is formed into a thin film, and then subjected to a chemical reaction or a carbonization reaction to obtain a carbon porous film which is a pore or a gap between the pores generated in the process; or a combination thereof Method of method.

The thinning technique differs from the vapor deposition method in that it is easy to control the film thickness thinly by a wet coating method using a spin coating, a die coating, or a gravure coating of a polymer solution in a non-vacuum environment, or as a wafer. In the production method, the rod shape is thinly cut and the polishing process is performed to thin the film, whereby the production with high productivity can be performed.

The fourth advantage of using a carbon to form a porous film is excellent in thermal characteristics and bending rigidity. The melting points and thermal expansion coefficients of amorphous carbon (aC), graphite (gC), and Si are as follows. That is, with respect to the melting point under normal pressure, carbon itself is the highest among all elements, aC and gC do not have a melting point, and Si is 1414 ° C, and thus carbon is excellent in heat resistance. Regarding the coefficient of thermal expansion, aC is 3.0 × 10 ^-6 /K, gC is 3.2 × 10 ^-6 /K, and Si is 3.9 × 10 ^-6 /K, so that the thermal stability of carbon is excellent.

On the other hand, regarding the bending stiffness corresponding to the hardness (physical strength) of the film, since the Poisson's ratio of carbon to Si is about 0.2, it is proportional to the product of the Young's modulus and the film thickness D. The Yang-type modulus of a-C is 30~33GPa, and the Yang-type modulus of g-C is 14GPa. In contrast, the Yang-type modulus of Si is 130~190GPa. The inventors of the present invention thought that Si is superior to carbon, and in fact, in the present embodiment, it is a carbon porous film, and the film thickness D can be made thicker than 2.5 times to 5 times or more of the Si flat film. Therefore, the present invention is used as a film for a protective film. The carbon porous film of the form becomes large.

[Technical Point 3]

Technical point 3 can be specified using structural parameters that limit the carbon porous membrane that satisfies the problem.

If the structural parameters of the carbon porous film are within the specific range reflecting the film strength of the actual carbon film or the empirical value of the manufacturing, and satisfying the specific range of the reference values of T, Δ, and D, it can be preferably used. A film for protective film of EUV light lithography. The following steps are followed in the following steps.

[Relationship between structural parameter group and reference value (Ti, △i, Di, i=1~3)]

(1) Step 1

In the cubic wall group pore model and the cubic axis group pore model of N=1 layer to 5 layer, a model for making various changes in d and α is produced. The optical constants n and k at λ = 13.5 nm of carbon (2.25 g/cm ³ ) determined according to Non-Patent Document 1 (9.61 × 10 ^-1 , 7.70 × 10 ^{-3 , respectively} ) and λ = 6.75 nm were used. The optical constants n and k (9.91×10 ^-1 , 7.70×10 ^{-4 , respectively} ), and the diffraction optical element design and analysis software DiffractMOD manufactured by RSoft Corporation by RCWA method, and the incident angle θ of each model is calculated. T, △, D at 6°. Further, T is a transmittance of 0 times, and Δ is a value obtained by subtracting the transmittance of 0 times from the total transmittance.

Further, in addition to the method of using the above DiffractMOD, the calculation of T, Δ, and D also uses the above-described G-Solver method. Although the former requires a long calculation time due to complicated calculation and high difficulty, it can correspond to any of the cubic wall group pore model and the cubic axis group pore model. On the other hand, although the latter calculation is relatively fast compared to the simple calculation time, it only corresponds to the cubic wall group pore model, and the calculation result is that the T value is the largest in the range of 70 to 100% of the transmittance T through one time. The increase is about 10%, and the Δ value is reduced by about 5% at the maximum in the range of 0 to 10% of the scattering amount Δ. In the present embodiment, unless otherwise specified, a calculation method that can be applied to any of the pore structure models is preferably used.

Using the software tool (multiple regression software) of EXCEL multivariate analysis commercially available from Esumi Co., Ltd., the obtained results were subjected to multiple regression analysis to obtain the first structural parameter group and the second structural parameter group of each pore structure model. The influence of T and △ on the carbon porous film.

<Step 1-1>

The influence of the first structural parameter group N, d, α on T and △ in the pore wall model of cubic wall group

As a result of the multivariate regression analysis of the first structural parameter group N, d, and α of the cubic wall group pore model, the multivariate regression equation of T at λ = 13.5 nm becomes T = [-7.65 × 10 ^-3 {α}-1.53×10 ^-2 {dN}+9.95×10 ^-1 ]×100 (19)

The coefficient of determination after the degree of freedom correction is R ^*2 =0.97, and the dependence of each factor obtained by the magnitude relationship of the absolute values of the corrected net partial regression coefficients is set as the absolute value of the net partial regression coefficient of each factor. The value of the percentage obtained by summing the absolute values of the net partial regression coefficients of all the factors) is 28%, and dN is 72%. In addition, in terms of the squareness of the case where the transmittance of the film for passing through the film for the second time is required to be approximately one time, it is preferable that the multiple regression formula of T is compatible with In(T). =[-1.13×10 ^-2 {α}-2.04×10 ^-2 {dN}+2.93×10 ^-2 ] (20)

R ^*2 =0.95

Approximate, but the formula (19) with a larger R ^{* 2} is used in the calculation below.

Further, the multivariate 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.

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, and the dependency ratio of each factor was α of 34% and dN of 66%. Furthermore, the multiple regression equation for T can be related to In(T)=[-2.16×10 ^-3 {α}-5.05×10 ^-3 {dN}+1.24×10 ^-2 ] (23)

R ^*2 =0.90

Approximate, but R &gt; ^{2 is} larger in the calculation below (22).

Further, the multivariate 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.

According to the results, in the cubic wall group pore model, the product of the wall thickness of the pores and the number of layers of the pores is the substantial thickness in the film thickness direction of the material constituting the film of Nd (corresponding to the film of the flat film) Thickness has a large influence on T, and it is inconspicuous that the α corresponding to the size of the pore affects the factor of the former. On the other hand, it is understood that α and Nd have an influence on Δ in terms of the form of the product of αNd. α corresponds physically to the aperture L (= λα), meaning that Δ is susceptible to the aperture.

<Step 1-2>

The influence of the first structural parameter group N, d, α of the cubic axis group pore model on T and △

According to the results of multivariate regression analysis of the first structural parameter group N, d, and α in the cubic axis group pore model, the multivariate regression equation for T at λ = 13.5 nm becomes T = [6.02 × 10 ^-3 {α}-8.69×10 ^-3 {dN ^1/2 }+1.00]×100 (25)

R ^*2 =0.86

The dependency ratio of each factor was α of 33% and dN ^1/2 of 67%. Furthermore, the multiple regression equation for T can also be related to In(T)=[6.86×10 ^-3 {α}-5.01×10 ^-3 {dN}-1.34×10 ^-2 ] (26)

R ^*2 =0.79

For the approximation, the larger formula (25) of R ^{* 2} is used in the calculation below.

Further, the multivariate regression equation with respect to Δ at λ = 13.5 nm becomes Δ = [1.99 × 10 ^-3 {dN ^1/2 } - 1.25 × 10 ^-2 ] × 100 (27)

R ^*2 = 0.71.

In addition, the multi-regression equation of Δ is described by doubling the value of the case where the scattering rate is required to pass through the film for the second time, and it is theoretically preferable to be both Δ= [9.14×10 ^-4 {dN}-7.55×10 ^-3 ]×100 (28)

R ^*2 =0.66

For the approximation, the larger formula (27) of R ^{* 2} is used in the calculation below.

On the other hand, the multiple regression equation for T at λ = 6.75 nm becomes T = [1.07 × 10 ^-3 {α} - 2.95 × 10 ^-3 {dN ^1/2 } + 1.00] × 100 (29)

R ^*2 = 0.91, and the dependency ratio of each factor becomes α of 22% and dN ^1/2 of 78%. Furthermore, the multiple regression equation for T can be compared with In(T)=[1.06×10 ^-3 {α}-1.51×10 ^-3 {dN}+2.84×10 ^-4 ] (30)

R ^*2 =0.91

Approximation, in terms of the integration with the formula (25), the formula (29) is used in the calculation below.

Further, the multivariate regression equation for Δ at λ = 6.75 nm becomes Δ = [9.06 × 10 ^-4 {dN ^1/2 } - 5.50 × 10 ^-3 ] × 100 (31)

R ^*2 = 0.63.

Furthermore, the multiple regression equation for △ can also be combined with △ = [4.34 × 10 ^-4 {dN} - 3.85 × 10 ^-3 ] × 100 (32)

R ^*2 = 0.62

Approximate, but the formula (31) where R ^{* 2 is} larger is used in the calculation below.

According to the results, it is understood that the value of dN ^1/2 corresponding to the dN of the cubic wall group pore model and corresponding to the substantial thickness in the film thickness direction in the cubic axis group pore model is T A large effect is caused, and the α corresponding to the size of the pores has no influence more than the factor of the former. On the other hand, regarding Δ, in the pore model of the cubic axis group, the pores are connected, and α has only a formal meaning, so it is regarded as α=1, which affects in the form of dN ^1/2 , that is, Refers to the effect of no pores.

<Step 1-3>

The influence of the second structural parameter group ρ, D, α in the cubic wall group pore model and the cubic axis group pore model on T and △

Then, the influence of the second structural parameter group ρ, D, and α on T and Δ is investigated. According to the results of multiple regression analysis of the second structural parameter group ρ, D, α in the pore wall model of the cubic wall group, the multiple regression equation for T at λ = 13.5 nm becomes T = [-1.26 × 10 ^-3 {Dρ(λα) ^1/2 }-9.52×10 ^-3 {ρD}+9.60×10 ^-1 ]×100(33)

R ^*2 = 0.98, and the dependency ratio of each factor becomes Dρ(λα) ^1/2 of 60% and ρD is 40%. Further, the multivariate regression equation with respect to Δ at λ = 13.5 nm becomes Δ = [9.72 × 10 ^-4 {Dρ(λα) ^1/2 } - 3.75 × 10 ^-3 (ρD) + 3.16 × 10 ^-3 ] × 100 (34)

R ^*2 = 0.93, and the dependency ratio of each factor becomes Dρ(λα) ^1/2 of 74%, and ρD is 26%.

On the other hand, the multiple regression equation for T at λ = 6.75 nm becomes T = [-6.62 × 10 ^-4 {Dρ(λα) ^1/2 } - 1.41 × 10 ^-3 (ρD) + 9.96 × 10 ^-1 ]×100 (35)

R ^*2 = 0.99, and the dependency ratio of each factor becomes Dρ(λα) ^1/2 of 81%, and ρD is 19%.

Further, the multivariate regression equation with respect to Δ at λ = 6.75 nm becomes Δ = [4.49 × 10 ^-4 {Dρ(λα) ^1/2 } - 1.11 × 10 ^-3 {ρD} - 1.84 × 10 ^-3 ] × 100 (36)

R ^*2 = 0.95, and the dependency ratio of each factor becomes 78% of Dρ(λα) ^1/2 , and ρD is 22%.

On the other hand, the result of the multiple regression analysis obtained by the second structural parameter group ρ, D, α in the cubic axis group pore model is that the multiple regression equation for T at λ = 13.5 nm becomes T = [- 1.59×10 ^-4 {Dρ(λα) ^1/2 }-1.59×10 ^-3 {ρD}+9.66×10 ^-1 ]×100(37)

R ^*2 = 0.99, and the dependency ratio of each factor becomes Dρ(λα) ^1/2 of 35%, and ρD is 65%.

Further, the multivariate regression equation with respect to Δ at λ = 13.5 nm becomes Δ = [1.59 × 10 ^-4 {Dρ(λα) ^1/2 } - 3.57 × 10 ^-4 (ρD) - 2.41 × 10 ^-3 ] × 100 (38)

R ^*2 = 0.91, and the dependency ratio of each factor becomes 70% of Dρ(λα) ^{1/2 and} ρD is 30%.

On the other hand, the multiple regression equation for T at λ = 6.75 nm becomes T = [-8.20 × 10 ^-5 {Dρ(λα) ^1/2 } - 3.27 × 10 ^-4 (ρD) + 1.00] × 100 ( 39)

R ^*2 = 0.99, and the dependency ratio of each factor becomes Dρ(λα) ^1/2 of 54%, and ρD is 46%.

Further, the multivariate regression equation with respect to Δ at λ = 6.75 nm becomes Δ = [7.60 × 10 ^-5 {Dρ(λα) ^1/2 } - 1.66 × 10 ^-4 {ρD} - 1.31 × 10 ^-3 ] × 100 (40)

R ^*2 = 0.93, and the dependency ratio of each factor becomes Dρ(λα) ^1/2 of 68%, and ρD is 32%.

As can be seen from the results, it can be seen that the variable {Dρ(λα) ^1/2 } and {ρD} in the form of the sharing factor and the product ρD of the apparent density ρ and the film thickness D in the form of the sharing factor can be obtained in a large form. For R ^*2 , ρD and T, △ together have a greater impact. ρD corresponds to the film weight of the average unit area in the film thickness direction, and therefore has a relationship with the amount of the substance substantially in the film thickness direction. If ρ is large, it is necessary to make D thinner, and if ρ is small, it can be increased. Big D.

(2) Step 2

According to the multiple regression equation shown in step 1, the influence of each structural parameter group on T and Δ can be qualitatively known. In the first step, in the case of the calculation, it is N≦5, and it is known that the first structural parameter group (N, d, α) satisfying the respective reference values (Ti, Δi, Di; i = 1 to 3) and Since the values of the second structural parameter group (ρ, D, and α) are estimated, the values of N satisfying the respective reference values of Ti and Δi under each α and d, N(Ti), and N(Δi) are used. Equation (2) finds values D (Ti) and D (Δi) of D satisfying the respective reference values of T and Δ. However, regarding Δi, it is presumed that R ^{* 2 of the} formula (27) and the formula (31) is slightly smaller, and the error is larger than that of Ti. Therefore, with respect to Δi, 1/2 of the value of the scattered amount obtained by definition is set as the upper limit of each Δi (for example, by definition, the 10% scattering amount should be set to Δ1, and the 5% scattering amount should be Set to the upper limit of △1). As a result, the amount of scattering when passing through the film for the secondary film twice corresponds to Δ1, Δ2, and Δ3, and is 10%, 5%, and 1%, respectively. Further, N(Ti), N(Δi), D(Ti), and D(Δi) mean the number of layers N _max and the film thickness D _max of the upper limit which satisfy the upper limit of each of the reference values of T and Δ, respectively.

According to the second step, the number of layers N _max satisfying the upper limit of each of the reference values of T and Δ can be quantitatively known based on the first structural parameters α and d, and can be quantitatively known based on the second structural parameters α and ρ. The film thickness D _max which is the upper limit of each of the reference values of T and Δ is the range of D.

As a result, the ρ becomes smaller, and the film thickness D _max which satisfies the upper limit of each of the reference values of T and Δ tends to increase (in particular, T increases exponentially). On the other hand, since the value of α and D _max fluctuates greatly with respect to the value of ρ, it cannot be said that there is no clearer than the tendency of ρ, and the larger the value of α with respect to T, the larger D _max increases, and α The larger the Δ becomes, the more D _max tends to decrease.

(3) Step 3

According to step 2, the range of structural parameters α, N, d, ρ, and D required to satisfy the respective reference values Ti, Δi, and Di (i = 1 to 3) can be obtained. However, in the present embodiment, in addition to the above, the range of the structural parameters α, N, d, ρ, and D satisfying the constraint 1 to the constraint 4 of the carbon porous film obtained in reality is satisfied. The carbon porous membrane of the subject.

. Constraint 1: 0.335nm≦d (41)

. Constraint 2: 1≦N (42)

. Constraint 3: 0.5≦α (43)

. Constraint condition 4: 1.0×10 ^-3 g/cm ³ ≦ρ≦2.25g/cm ³ (44)

The constraint 1 and the constraint 2 are those relating to the microstructure parameters described under the definitions of d and N, which are calculated before calculation. Further, regarding d, it is preferably 1.35 nm or more. Further, it is preferable that N is 2 or more, and if the numerical value is large, it is considered that pores having a cubic shell shape or a cubic frame shape having different microstructure parameters in each pore structure model satisfy the respective reference values. A film structure formed by laminating in the film thickness direction.

The constraint 3 is a structural parameter shared by the microscopic and macroscopic, and the alpha value referred to herein represents a value corresponding to L (peak) of the pore distribution. The lower limit is set to 0.5 in accordance with the meaning of the embodiment. The carbon porous film obtained in reality contains pores having a pore diameter smaller than the α value, and it is difficult to exclude the pores thereof. However, the pores having a small pore diameter contribute little to the increase in the film thickness of the carbon porous film, and the transmittance is minimized by the layer thickness of the carbon layer, which is not preferable. Therefore, the pore distribution is preferably one in which the sharp shape of L (peak) is concentrated. The upper limit of α is obtained from the step 2, and based on the empirical L(max) ≒ 1.5 × L (peak) ~ 3 × L (peak), it is considered that the upper limit of α corresponding to the average pore diameter in the carbon porous film is considered. [L(peak)/λ] is set according to step 2 When the upper limit of α is 1/1.5 to 1/3 of the upper limit of α, the maximum pore diameter in the carbon porous film obtained in practice can be suppressed to be less than or equal to the upper limit of α obtained in the second step, and thus it is preferable.

The constraint condition 4 is defined by the lower limit value of the apparent density ρ of the carbon aerogel obtained in reality. The reciprocal of P and αλ/d is related to equation (5) in the cubic wall group pore model, and is related to equation (8) in the cubic axis group pore model. Λλ/d is an indicator of the strength of each pore itself according to the configuration of the item. Specifically, if the value is small (if ρ is large), the pore itself becomes a firm one.

Based on the constraint conditions 1 to 4 of the carbon porous film obtained in reality, according to step 2, the structural parameters D and ρ required to satisfy the respective reference values Ti, Δi, and Di (i = 1 to 3) are used. The ranges of α and d are obtained in the following manner.

The range of the film thickness D is 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 axis group pore model. In the cubic wall group pore model, D=100nm~517nm at λ=13.5nm, D=100nm~1711nm at λ=6.75nm, and the upper limit of D is the smallest in each pore structure model. ρ, the maximum αλ / d is achieved.

Regarding the range of apparent density ρ, in the cubic axis group pore model, ρ = 1.0 × 10 ^-3 ~ 9.4 × 10 ^-1 g / cm ³ at λ = 13.5 nm, and ρ = at λ = 6.75 nm. 1.2 × 10 ^-3 ~ 2.1g / cm ³ . In the cubic wall group pore model, ρ = 8.2 × 10 ^-2 ~ 5.6 × 10 ^-1 g / cm ³ at λ = 13.5 nm, and ρ = 8.8 × 10 ^-2 ~ 1.7 at λ = 6.75 nm g/cm ³ . On the other hand, regarding the range of αλ/d which is an index of the strength of each pore itself, the upper limit of ρ corresponds to the smallest pore structure model and the corresponding αλ/d under the corresponding λ, and the lower limit of ρ Corresponds to the largest αλ/d. That is, when the range of αλ/d is expressed in a form corresponding to the range of ρ, it is αλ/d=81 to 1.25 at λ=13.5 nm in the cubic axis group pore model, and is λ=6.75 nm. Λλ/d=75~0.16. In the cubic wall group pore model, αλ/d=81~10 at λ=13.5 nm and αλ/d=75-1.7 at λ=6.75 nm.

Regarding the range of the pore size parameter α, in the cubic axis group pore model, at λ= α = 0.5 to 181 at 13.5 nm and α = 0.5 to 726 at λ = 6.75 nm. In the cubic wall group pore model, α = 0.5 to 20 at λ = 13.5 nm and α = 0.5 to 86 at λ = 6.75 nm on the basis of 0.335 nm ≦d. Further, α = 0.5 to 18 at λ = 13.5 nm and α = 0.5 to 84 at λ = 6.75 nm on the basis of 1.35 nm ≦d.

The range of the wall thickness of the pores or the thickness d of the column is d = 0.335 nm to 30.5 nm at λ = 13.5 nm and d = 0.335 nm to 60.6 at λ = 6.75 nm in the pore model of the cubic axis group. Nm. In the cubic wall group 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.

In the following, an example of a preferred structure of the film for a film (in the case of d≧1.35 nm) is shown in the step 3. Furthermore, each range of values of the structural parameter group and the constraint condition is in the form of {α, d [unit nm], D [unit nm], ρ [unit g/cm ³ ], αλ/d} in each of the pores. Structural Models, Examples of Structures for Each Wavelength of EUV Lights. Furthermore, {A1, B1, C11~C12, D1, E1}~{A2, B1, C21~C22, D2, E2} mean that the pores can be made on the basis of the wall thickness or the column thickness d being the B1 value. The dimension parameter α is a range in which the range of A1 to A2 corresponds to each α, and the reference value of the present embodiment is obtained within a range in which the film thickness D is C11 to C22 and C21 to C22.

<Step 3-1>

As a membrane for film protection, the ideal structure - T3. Δ3. D3

The characteristic structure 1 is a structure which is preferable as a film for a film. For the cubic axis group pore model, λ = 13.5 nm has {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 carbon porous membrane with structural parameters.

In the case where the physical properties of T = T3, Δ = Δ3, and D = D3 are obtained, the carbon porous film having the structural parameters is the most suitable structure as the film for the protective film. Especially with { 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} The structural parameters of the carbon porous film are ρ ≧ 1.0 × 10 ^-2 g / cm ³ , depending on the film strength Better words.

In the cubic wall group pore model, there is no carbon porous film having structural parameters of obtaining physical properties of T=T3, Δ=Δ3, and D=D3 at λ=13.5 nm and 6.75 nm.

<Step 3-2>

Transmission priority structure in the cubic wall group pore model - T2. Δ2. D1

Regarding the characteristic structure 2, in the cubic layer group pore model λ = 13.5 nm, as a structure having a high transmittance priority, there is a carbon having a structural parameter which obtains physical properties of T = T2, Δ = Δ2, and D = D1. Porous membrane. That is, it has {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}

The carbon porous film having the structural parameters, ρ ≧ 1.0 × 10 ^-2 g / cm ³ , is preferable from the viewpoint of film strength.

<Step 3-3>

Film thickness priority structure - T1. △1. D3

As the characteristic structure 3, there is a carbon porous film having a structure in which the film thickness is preferred, that is, a structural parameter having physical properties of T = T1, Δ = Δ1, and D = D3. For the cubic axis group pore model, λ = 13.5 nm has {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}

A carbon porous membrane having structural parameters.

In particular, it has {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}

The carbon porous film having the structural parameters has a pH of 1.0 × 10 ^-2 g / cm ³ , which is more preferable from the viewpoint of film strength.

It has {α, d, D, ρ, αλ/d}={8, 1.35, 500~517, 8.2×10 ^-2 , 80} at λ=13.5 nm of the cubic wall group pore model.

A carbon porous membrane having structural parameters.

Each of the ranges of the values of the structural parameter groups and the control conditions described above is an example of a preferred structure of the film for a film, and the transmittance T of the EUV light passing through the primary carbon porous film may be 84% or more. A film for a protective film for EUV having a scattering amount Δ of 10% or less and a film thickness D of 100 nm or more. For example, when the calculation is performed using the above G-Solver, the wavelength λ of the EUV light is set to 13.5 nm, the density W of the graphite is set to 2.25 g/cm ³ , and the apparent density (g/cm ³ ) of the carbon porous film is set. When ρ is set and the film thickness is D (nm), the carbon porous film can be preferably used in the cubic wall group pore model using the first structural parameter to satisfy the following formulas (1) to (1). 5) A film for a protective film for EUV in the range of structural parameters.

≦30 (α: pore size parameter) (1)

0.335≦Nd≦13 (N: number of pores in the film thickness direction (number), d: wall thickness of pores (nm)) (2)

Λλ/d≦81 (λ: exposure wavelength (nm)) (3)

Where 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)

In the same manner, the carbon porous film can be preferably used as the EUV film for satisfying the structural parameters of the following formulas (6) to (9) in the cubic wall group pore model using the second structural parameter. membrane.

≦ 30 (α: pore size parameter) (6)

Λλ/d≦81 (λ: exposure wavelength (nm)) (7)

0.08g/cm ³ ≦ρ≦0.7g/cm ³ (8)

D: 100 nm ≦D ≦ 850 nm (9)

In this way, it is preferable to use a numerical formula in accordance with the exposure wavelength λ and the approximate pore structure model in accordance with an appropriate calculation method, and it is preferable to use the film for the EUV film.

As described above, the present invention is a film for a protective film which is composed of a carbon porous film and is known from [Technical Point 3], according to [Technical Point 1] and [Technical Point 2]. The film thickness D of the film for a film is 100 nm - 63 micrometer.

Further, as a further improvement of the carbon porous film of the present embodiment [supplemental treatment], a combination of well-known techniques may be mentioned.

In the first example, as described in Patent Document 2, in order to prevent oxidation and reduction of the carbon porous film by light from a high-output light source of EUV, a known sputtering method is used within a range that satisfies the target value of the problem of the present invention. In a method such as a vacuum deposition method, Si, SiC, SiO ₂ , Si ₃ N ₄ , yttrium, molybdenum Mo, Ru, yt Rh or the like of several nm is coated on one surface or both surfaces of the surface of the carbon porous film of the present embodiment. In the case of a SiC film having a low extinction coefficient of EUV light and a refractive index close to 1.0 and reacting with carbon to form a strength of several nm on the surface of the carbon film, Si is particularly preferable.

In the second example, the carbon porous film of the present embodiment has a film thickness that is highly transparent to EUV light and has sufficient durability in practical use. However, when further film strength is required, In the range of the target value of the problem of the present invention, the screen is used as a support film in the case of Patent Document 3, Patent Document 4, Patent Document 5, and Non-Patent Document 2 (the extinction coefficient and Δn are small, and it is easy to use general-purpose products). From the viewpoint of the form acquisition, the material is preferably Si, Zr, Mo, Titanium Ti, NiNi, Al, Cu, Cu, etc. and the like. In this case, the transmittance is reduced by 10% or more depending on the thickness of the support film (the thickness of the screen is several tens μm, the wire diameter of the sieve is several tens μm, and the size of the hole is several hundred μm to several mm). Therefore, the carbon porous film of the present invention alone has a transmittance T of T2 and T3. Further, the support film hardly affects the amount of scattering Δ.

[Replenishment] describes the method of correcting structural parameters. [Technical Point 3] The transmittance T and the scattering amount Δ of the present embodiment expressed by the formulas (19) to (40), (1) to (5), and (6) to (9). The relationship between the structural parameter group of the carbon porous membrane or the structural parameter group used to obtain the reference values of T, Δ, and D is based on the (premise 1) and (premise 2) wavelengths of the EUV light. The values of the optical constants n and k of the graphite at a density of W = 2.25 g/cm ³ at λ = 13.5 and λ = 6.75 nm were calculated by calculating the transmittance T and the scattering amount Δ. Therefore, when the value of the graphite is changed before the density W of the graphite is changed, the structural parameters of the carbon porous film of the present embodiment are calculated by recalculating T and Δ in the same manner as in the steps 1 to 3 by using the corresponding new optical constant. The constraint range or Ti, △i, Di can be. For example, if the value of the graphite before the density W becomes smaller, the extinction coefficient k of the carbon becomes lower, and the refractive index n is close to 1, so the thickness D of the structural parameter, the apparent density ρ, and the pore size parameter α are limited by the embodiment. The scope has expanded.

2-2. Method for Producing Film for Protective Film of the Present Embodiment

In the following, the method for producing a film for a protective film of the present embodiment is described. However, the carbon porous film as the film for a protective film of the present embodiment is not limited to the production method and the examples thereof. Fig. 5 is a view showing a method of producing a film for a protective film.

There are various methods for obtaining a carbon porous film. The first method is a method in which the melting and the destruction are not caused by sintering or carbonization, and the size of the pores of the target is twice as large. After adding a binder to the fine carbon precursor particles or carbon particles of about several tens of times, the film is formed into a film, and then sintered and carbonized to obtain a carbon porous film having pores as pores.

The second method (method A) is a method of forming a film of a solvogel (for example, a hydrogel) containing a large amount of a solvent by a sol-gel method using a raw material in which a sol-gel transition first occurs, and then The structure of the solvogel does not disintegrate only by drying the solvent, thereby obtaining an aerogel film containing a large amount of bubbles, and finally carbonizing the aerogel film, thereby obtaining a carbon porous film as a carbon aerogel. .

The third method (method B) is a method in which a chemical reaction or a carbonization reaction is carried out in a molecular structure in which a structure is immobilized and a bubble is generated in a chemical reaction process or a carbonization process, and bubbles generated in the processes are obtained. Or a carbon porous membrane as a pore. It is relatively easy to produce a carbon porous film having a pore diameter of about 0.5 to 10 times the wavelength of EUV light by controlling the particle diameter according to the first method, but it is difficult to obtain a low density of an apparent density of 1.0 g/cm ³ or less. Carbon porous membrane. The carbon porous film of the present embodiment can be obtained by the second and third methods.

The carbon porous film of the present embodiment is a technique for producing a conventional carbon porous film as mentioned in the second advantage of [Technical Point 2]. However, these manufacturing techniques are different in [Technical Point 4] and [Technical Point 5].

[Technical Point 4]

Technical point 4 is a film forming technique for introducing a film. In the technical point 4, the film for a film for use as a conventional carbon porous film is not considered in consideration of the use of the carbon porous film of the present embodiment, and a film forming technique for obtaining a film is additionally added. In other words, in the method for producing a carbon porous film of the present embodiment, a film forming step (step A2, step B2, step AB2) suitable for film formation and a preparation step for obtaining a coating liquid for the film (step A1) Step B1 and step AB1) become important technical points.

In the modulating step, it is preferred to adjust the composition, molecular weight, and temperature of the coating liquid. The viscosity of the coating liquid is lowered, and the film can be coated to form a film, and the film thickness after drying is several tens nm to several hundreds μm. The reason is that in the structure fixing, drying step (step A3, step B3, step AB3) or carbonization step (step A4, step B4, step AB4), the film thickness is about 0.5 to 3 times that of the coating, and the carbonized film The thickness becomes 100 nm to 63 μm. In order to lower the viscosity of the coating liquid, it is only necessary to reduce the concentration of the final carbonaceous solute in the coating liquid within the range of the manufacturing parameters described in the technical point 5. In particular, when the coating liquid is a polymer solution, it is preferred to lower the molecular weight to such an extent that the coating film does not break when the coating film is peeled off from the coating after drying.

Further, as a coating method for obtaining a film, it is preferred to use a wet coating method in which a low viscosity coating liquid can be applied thinly, instead of a dry coating method represented by a vapor deposition method. Specifically, a coating method which is less productive but advantageous for thin film formation such as a spin coating method, a nozzle scanning coating method, an inkjet coating method, or the like; or a bar coating, a gravure coating, a mold can be used. Thin film formation such as coating, blade coating, and conformal coating has a limit, but a coating method which is highly productive by continuous coating called roll-to-roll. Further, a uniform film can be obtained by appropriately adjusting not only the viscosity of the coating liquid, the composition or the coating method but also the coating conditions such as the coating speed, the coating temperature, and the coating time.

[Technical Point 5]

Technical Point 5 In order to obtain a carbon porous film having the structural parameters described in [Technical Point 3], the production parameters are adjusted according to each production method (the type of solute which becomes carbonaceous and its molecular weight, solution composition, solution concentration, cross-linking catalyst) The type, dehalogen species and its concentration, drying conditions, carbonization conditions, etc.), the details of which will be described below.

2-2-1. Method for producing carbon aerogel-based carbon porous membrane

The method A (the second method described above) for obtaining the carbon porous film of the present embodiment is disclosed in the reference A, the US Pat. No. 4,873,218 (hereinafter referred to as Reference B), the field door, the surface, 38 (1), 1 9 (2000) [hereinafter referred to as reference C], Japanese Patent Laid-Open Publication No. Hei 8-508535 [hereinafter referred to as Reference D], and R. Saliger et al., J. Non-Crystalline The method described in Solids, 221, 144-150 (1997) [hereinafter referred to as Reference E]. In these documents, carbon materials having mesopores used for heat insulating materials, batteries, capacitors, and the like have been described, and the use of the present embodiment has not been considered at all. However, the application parameters of the present embodiment can be applied by adding a film forming technique of a film and adjusting the manufacturing parameters so that a hydrogel film having a small film thickness can be obtained.

That is, as shown in FIG. 5, the step A1 is a monomer containing at least one of resorcin (R), phenol, catechol, phloroglucinol and other polyhydroxybenzene compounds as a carbonaceous raw material. And a monomer in which at least one of formaldehyde (F) and furfural is dissolved in water, and further, gelled (polymerized) potassium carbonate (K ₂ CO ₃ ) as a basic catalyst (Ca), sodium carbonate Any one or more of an alkali metal carbonate such as (Na ₂ CO ₃ ), potassium hydrogencarbonate (KHCO ₃ ), or sodium hydrogencarbonate (NaHCO ₃ ) or an alkali metal hydrogencarbonate is dissolved in water (Wa), and these are mixed. The coating liquid A (RF viscous liquid) was prepared.

Step A2 is followed by the step A1, and the coating liquid A is applied so as to be easily peeled off from the back, and the film thickness after carbonization is 100 to 850 nm (the above-mentioned bar coating or spin coating, etc.) and film formation. On the release film or release substrate. In this case, it is preferable to coat the periphery of the release film or the release substrate and to seal the coating film so as not to flow out from the release film or the periphery of the release substrate, and to evaporate the solvent (water) to apply the liquid. The composition is sealed in such a manner that the composition does not change or the region where the pores of the membrane are not deformed.

Step A3 is followed by step A2 at room temperature (20 ° C) to 100 ° C to increase the temperature stepwise or to stand for several days (1 to 14 days), so that it is fully gelled (polymerized) to obtain film-like water. Gel film. In order to obtain a solid hydrogel film earlier, it can be heated (50 to 100 ° C) while standing as shown in Reference D, but in order to obtain a hydrogel film having a large pore diameter, it is preferred to heat the film. low.

Then, the hydrogel film is peeled off from the release film or the release substrate, and the solvent in the hydrogel film is replaced with acetone or cyclohexane in order to dry the pore shape and the pore shape. And performing supercritical CO2 drying (CO ₂ supercritical drying) [drying method 1] or freeze-drying (after replacement with a third butanol or the like if necessary) [drying method 2], or at room temperature to 100 Drying at a temperature of °C or drying under reduced pressure (hot air, drying under reduced pressure) (if necessary, after replacement with the treatment liquid used in the drying method 1 or the drying method 2) [drying method 3] in the hydrogel film The water is scattered to obtain a porous RF-based aerogel film. At the time of replacement, in order to suppress the change in the pore diameter and the pore shape by contact with the replacement liquid, it is preferred to gradually increase the replacement of water, acetone, cyclohexane, and third butanol from the water in the hydrogel film. Concentration or increase the number of substitutions.

Moreover, as a drying method, in order to suppress the capillary shrinkage by the interfacial tension of the solvent at the time of drying as much as possible, it is preferable [drying method 1]. However, instead of supercritical drying, [Drying Method 2], Reference D, and Reference E shown in Reference C, [Drying Method 3] also sacrifices the pore size and pore shape (for shrinkage) but for lower It is advantageous in suppressing the manufacturing cost, and can be used in the present embodiment.

Step A4 is followed by step A3, carbonizing the RF aerogel film in an inert atmosphere or under a nitrogen atmosphere at 600 to 3000 ° C for 10 minutes to 20 hours, thereby obtaining carbon gas condensation as an RF system of the present embodiment. A carbon porous film of glue. The carbonization treatment can be carried out by using a solid film, carbonization of a sheet, a fixed bed method for activation treatment, a moving bed method, a carbonization of a tunnel kiln or the like, and an activation production method instead of pulverizing a carbon precursor.

There is a tendency that the pore diameter of the RF-based aerogel shrinks with carbonization, and the ratio of shrinkage decreases as the carbonization temperature becomes higher, but the pore diameter and pore distribution become smaller. Therefore, the carbonization temperature can be adjusted according to the aperture set as the target. Usually, the carbonization temperature is carried out at 700 to 1500 ° C, and when it is necessary to increase the film strength, electrical conductivity, and thermal conductivity, the treatment can be carried out at 2000 to 3000 ° C. Further, the pore structure and the pore distribution may be enlarged by adjusting the obtained carbon porous film as needed to adjust the pore structure. As the activation method, a gas activation method in which calcination is carried out using an activation gas such as steam, hydrogen chloride, carbon monoxide, carbon dioxide or oxygen is preferred.

Further, in the carbonization treatment, if the aerogel film is severely shrunk and carbonized in a non-stretched state, the film is likely to wrinkle. Therefore, it is preferably fixed by a frame or sandwiched between two graphite sheets or The aerogel film is carbonized in a stretched state between the graphite sheets, and the structure is thermally stabilized in the air or under iodine (I ₂ ) vapor at 150 ° C to 250 ° C in advance.

The formation mechanism of the RF aerogel described in Figure 1 of Reference C and RWPekala, FM. Kong, Polym., Prep, 30, 221-223 (1989) [hereinafter referred to as Reference F] Schematic diagram, electron micrograph of RF aerogel and RF carbon aerogel as its carbide.

The aggregate of the beaded microparticles forms a carbon porous membrane as an RF-based carbon aerogel. It can be seen that although the actual carbon porous membrane has an intermediate structure of a cubic axial group pore structure model and a cubic wall group pore structure model, it is hard to say that the pore structure of the RF system carbon aerogel is similar to a cubic shaft group pore. The structure of the structural model.

Further, in Figs. 10 to 13 of Reference A, a graph of a pore distribution of an RF-based carbon aerogel and a graph of Debye-Porod analysis of SAXS are shown. According to Fig. 10 of the literature, the dependence of the type of catalyst on the pore distribution of the RF carbon aerogel can be obtained by the peak of the alkali metal hydrogencarbonate larger than the alkali metal carbonate, the radius r (peak), the pore diameter L. As can be seen from Fig. 12 of this document, when the R/C becomes larger, the pore diameter L becomes larger as the R/C becomes larger, but the pore distribution becomes wider, and the peak height of the peak of the pore distribution curve also becomes lower.

Further, according to Fig. 13 of the document, when the R/C is 100 or less (for example, 200) or less, the slope of the straight line of the Debye-Porod diagram is close to -4, so that the pore shape is close to a spherical shape irrespective of the type of the catalyst.

Hereinafter, based on the representative experimental values described in Reference A, Reference B, and Reference C, a multivariate regression equation, Equation (36), and Formula (37) which are assumed to be a composition ratio when the following conditions are obtained and the obtained structural parameters are obtained. In the step A1, R and F are prepared in a carbonaceous material, and Na ₂ CO ₃ is prepared in the form of Ca to prepare a coating liquid A having various composition ratios, and the coating liquid is applied by spin coating as step A2. After A is formed into a film to obtain a hydrogel film, as a step A3, the hydrogel film is gelated (polymerized) at room temperature to 100 ° C, and subjected to CO ₂ supercritical drying or freeze drying or hot air drying to obtain gas. After the gel film, the aerogel film was carbonized at 1000 ° C as step A4, and finally the carbon porous film of the present embodiment was obtained. The apparent density becomes ρ=-1.27×10 ^-1 ×ln(R/Ca)+7.07×(R/Wa)+7.24×10 ^-1 (45)

R ^*2 = 0.92, and the dependency ratio of each factor becomes ln(R/Ca) of 36%, and R/Wa is 64%.

Further, the pore radius r becomes 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, the dependency ratio of each factor was ln(R/Ca) of 39%, ln(R/Wa) was 37%, and ln(R/F) was 25%. Further, α corresponding to the pore radius r can be obtained by doubling r and dividing by λ according to the formula (18).

The following cases are known from the formulas (45) and (46). As the molar ratio R/Ca of R and Ca increases, the apparent density ρ becomes smaller, and α corresponding to the pore radius r becomes larger. Further, according to the above-mentioned cited document 4, when the influence of the type of Ca is increased in the order of K ₂ CO ₃ ≒Na ₂ CO ₃ <NaHCO ₃ <KHCO ₃ and the R/Ca becomes small, the pore distribution becomes sharp. If 0 < R / Ca ≦ 200, spherical pores can be obtained, and if R / Ca > 800, disc-shaped pores can be obtained. Therefore, in order to obtain a spherical fine pore and a sharp pore distribution, it is preferred to use an alkali metal hydrogencarbonate and to reduce R/Ca as much as possible.

On the other hand, as the molar ratio R/Wa of R and Wa increases, ρ becomes larger, and α becomes smaller. Further, as the molar ratio R/F of R and F increases, α increases. Therefore, in order to obtain larger pores, it is preferable to reduce R/Wa as much as possible and to increase R/F as much as possible.

Further, in the case of approximating the second structural parameter group and the multi-regressive equation of T and Δ, that is, the cubic wall group pore model, if λ = 13.5 nm, the equations (33) and (34) are used, and if λ = At 6.75 nm, the equations (35) and (36) are used. In the case of the approximate cubic axis group pore model, if λ = 13.5 nm, the equations (37) and (38) are used, and if λ = 6.75 nm Then, using the formulas (39) and (40), the composition range of Ti, Δi, and Di satisfying the problem of the present embodiment can be known.

By using a sol-gel method in the above manner, a film of a solvent-containing gel (for example, a hydrogel) containing a large amount of a solvent is formed by using a material which is first subjected to sol-gel conversion, and then the solvent is not disintegrated in a structure. Only the solvent is dried and removed, whereby a large amount of aerogel film containing bubbles is obtained, and finally the aerogel film is carbonized, whereby the carbon porous film of this embodiment as a carbon aerogel can be obtained.

2-2-2. Method for producing a halogenated vinyl resin or a vinylidene halide resin-based carbon porous film

The method B (the third method) of the present invention is disclosed in Japanese Patent Application No. 4,871,319 (hereinafter referred to as Reference G), Yamashita Shunya, Shioya Masahiro, Carbon, No. 204, 182-191. (2002) [set as reference H]. These references G or reference H are described in the form of a manufacturer of a mesoporous carbon material used for a catalyst supporting material, a gas absorbing material, a gas separating material, an electrode material, etc., and completely The application in this embodiment is not considered. However, it is applicable to the use of the present embodiment by adjusting the manufacturing parameters by adding a thin film forming technique and obtaining a halogenated vinyl resin film or a vinylidene halide resin film having a small film thickness.

That is, as shown in FIG. 5, as the step B1, the weight ratio of the halogen in the carbonaceous raw material using a halogenated ethylene resin having a halogenated ethylene composition of 60 mol% or more or a halogenated ethylene copolymer (collectively referred to as a halogenated vinyl resin) is 60 wt. More than or equal to high-halogenated ethylene resin or vinylidene halide composed of more than 60% by mole of a vinylidene halide or a vinylidene halide copolymer (collectively referred to as a vinylidene halide resin) (the following treatment of high halogenated ethylene equivalently) The base resin and the vinylidene halide resin are simply referred to as vinylidene halide resins unless otherwise specified. The solution obtained by dissolving the resin in a good solvent or the fine particles of the vinylidene halide resin dispersed in water is prepared, and the solutions and the latex are collectively referred to as a coating liquid B.

Step B2 is applied to the release film or the release substrate by the carbonization of the coating liquid B after the step B1, and the film thickness is from 100 nm to 63 μm, and the temperature is below the boiling point of the solvent at room temperature to solvent. The solvent or water was scattered by hot air under reduced pressure to obtain a resin film (vinylidene halide resin film) of a film-shaped vinylidene halide resin.

Step B3 is followed by step B2, using the following solution to carry out dehydrohalogenation reaction treatment on the vinylidene halide resin film at a temperature below the boiling point of the room temperature to the mixed solution for 1 second to 2 weeks, thereby obtaining a vinylidene halide resin system. a carbon precursor film which is an aqueous solution of an alkali metal hydroxide [potassium hydroxide (KOH), sodium hydroxide (NaOH), etc.) and/or an amine solution [ammonia (NH _{3 )} a solution of dehydrohalogenating agent (alkali) of 1,8-diazabicyclo[5,4,0]-7-undecene (DBU), etc.; tetrahydrofuran (THF), dimethylformamidine A good solvent such as a good solvent for dissolving a part or all of a vinylidene halide resin such as an amine (DMF); and a mixed solution of a poor solvent of a vinylidene halide resin such as water, an alcohol and/or an ether. Further, there is a case where the mixed solution is phase-separated depending on the composition. The mixed solution used in the present embodiment is a component which does not undergo phase separation, and is required for the dehydrohalogenation reaction of the carbon precursor to be excellent in reproducibility.

In step B2 and step B3, in step A2 and step A3, the coating film may be directly immersed in the mixed solution, and the gelation of the coating film on the release film or the release substrate may or may not be carried out. The coating film is specifically subjected to a peeling operation after being dried by hot air. Crosslinking (structure immobilization) caused by dehalogenation and hydrogenation of the coating film occurs by contact with the mixed solution, and the vinylidene halide resin film is released from the release film or the dehalogenated hydrogen gas generated The mold substrate is naturally peeled off. Therefore, a vinylidene halide resin film can be obtained in a very short time as compared with the method A.

Further, in the dehalogenation hydrogenation of the coating film of the step B3, a polyene structure (meaning a molecular skeleton structure having -C=C- or C≡C-) is generated in the vinylidene halide resin film. The crosslinked structure and the bubbles generated by the dehydrohalogenation become a vinylidene halide resin-based carbon precursor film in which many of the bubbles remain in the film. The carbon precursor film can undergo dehydrohalogenation reaction and carbonization (amorphous carbonization, even in the subsequent step B4) due to a majority of the crosslinked structure. Graphitized) without melting.

Step B4 is the following method: after step B3, the vinylidene halide resin-based carbon precursor film is subjected to stretching under an inert atmosphere or a nitrogen atmosphere at 600 to 3000 ° C in the same manner as in step A4. The carbonized carbonization was carried out in a minute to 20 hours to obtain a vinylidene halide resin-based carbon porous film of the present embodiment.

The control of the pore size and the pore distribution by the method B depends on the composition of the high halogenated ethylene and the vinylidene halide in the resin, the molecular weight of the resin, and the resin concentration in the coating liquid B in the step B1. The higher the value, the smaller the aperture becomes. Further, in step B2, the pores in the film can be made sharp by making the film thickness thin. Further, the higher the concentration of the alkali metal hydroxide, the amine or the like (dehydrohalogenating agent) in the mixed solution in the step B3, the higher the concentration of the good solvent of the vinylidene halide resin in the mixed solution, and the pore diameter becomes The bigger it is. In the step B4, as in the step A4, the carbonization temperature becomes higher as the pore diameter becomes smaller, but the pore diameter and pore distribution can be increased at 600 to 1200 ° C depending on the amount of halogen remaining in the carbon precursor. . Further, similarly to the step A4, the pore structure and the pore distribution can be increased by the activation treatment to adjust the pore structure. An example of the reference G and the reference H will be described below as an example of the method B.

Step B1 uses THF as a good solvent for PVDC resin to dissolve vinylidene chloride (VDC) in a carbonaceous raw material to form a resin of a vinylidene chloride resin or a vinylidene chloride copolymer of 60 mol% or more (collectively referred to as PVDC resin). ), the coating liquid B was prepared.

In the step B2, the coating liquid B was spin-coated on the glass release substrate so that the film thickness after carbonization was 100 to 850 nm, and hot air drying was performed at 80 ° C to obtain a film-form PVDC resin film.

In the step B3, the PVDC resin film is subjected to a dehydrochlorination reaction treatment (de-HCl treatment) using a mixed solution of an alkali metal hydroxide KOH aqueous solution, a good solvent THF, and a poor solvent methanol to obtain a PVDC-based carbon precursor film.

The final step B4 can be used to treat the PVDC carbon in a nitrogen atmosphere at 600~3000 °C. The precursor film was subjected to stretching and heating carbonization to obtain a PVDC-based carbon porous film of the present embodiment.

As the PVDC resin, those composed of [0011] to [0012] of Reference G can be used. The higher the molar content of the VDC component in the PVDC resin, the more the polyene structure produced by the dehydrochlorination reaction of the step B3 in one molecule becomes more likely to occur in the cross-linking structure between the plural molecules, and is insoluble. It is preferred to melt and directly carbonize in a solid state.

However, the VDC composition of 100 mol% of the PVDC resin is difficult to uniformly dissolve, and the PVDC film is hard and brittle and difficult to use, and thus is preferably a vinylidene chloride copolymer (VDC copolymer). The VDC molar composition in the VDC copolymer is preferably 0.6 (60 mol%), preferably 0.8 (80 mol%) or more, more preferably 0.9 (90 mol%) or more.

Further, the usual PVC resin given by the structural formula of (-CH ₂ -CHCl-) _n [Cl content: 57 wt%] is a structural formula of [(-CH ₂ -CHCl-) ₄ - CHCl-CHCl-] _n [Cl content: 61% by weight] of chlorinated PVC resin or chlorinated rubber such as [(-CHCl-C(CH ₃ )Cl-CHCl-CHCl-) _n [Cl content: 68% by weight] A highly chlorinated PVC resin having a chlorine content (Cl content) of more than 60% by weight can be obtained in the same manner as in the case of (-CH ₂ -CCl ₂ -) _n [Cl content: 73% by weight] of the PVDC resin in the step B3. The higher crosslinked structure can be carbonized without being melted even in the case of carbonization in the step B4, and can be used as the carbonaceous raw material of the present embodiment.

As the coating liquid B, an aqueous dispersion of a PVDC resin called latex or a PVDC resin dissolved in THF, 1,4-two shown in [0014] of Reference G can be used. A PVDC resin solution obtained in a good solvent of a PVDC resin such as alkane, cyclohexane, cyclopentanone, chlorobenzene, dichlorobenzene, DMF, methyl ethyl ketone or ethyl acetate. The good solvent is preferably THF or DMF.

The PVDC-based carbon precursor film can be subjected to de-HCl treatment using the composition or processing conditions of the alkaline treatment liquid shown in Reference [0014] to [0015], and the PVDC-based carbon porous membrane can be used as a reference. G is carried out under carbonization conditions as shown in [0017]. In addition, since the PVDC resin film and the PVDC-based carbon precursor film of the present embodiment are thin films, The alkali (base) concentration or the good solvent concentration, the de-HCl treatment temperature, and the de-HCl treatment or carbonization treatment time can be suppressed lower and shorter than the patent document.

A TEM photograph of a PVDC-based carbon porous film is shown in Fig. 3 of Reference G. Figure 2 of this document is a graph showing the pore distribution of a PVDC-based carbon porous membrane. According to Fig. 3 of the document, it is known that a PVDC-based carbon porous film is formed around a spherical majority of pores of the pore wall. According to Fig. 2 of the literature, pores of L≒13 nm (α≒1.0) form carbon in a majority. In the porous membrane. In this way, the vinylidene halide-based carbon porous film tends to have a thick and thick carbon porous film as compared with the carbon aerogel-based carbon porous film. Although it is considered that the realistic carbon porous membrane has an intermediate structure of a cubic pore group pore structure model and a cubic wall group pore structure model, it is known that the pore structure of the vinylidene halide-based carbon porous membrane is similar to a cubic wall group. The structure of the pore structure model.

The method of effectively utilizing Reference H is described below. Reference H describes the following method: using a vinylidene fluoride resin (PVDF resin) film instead of the PVDC resin, and using a mixed solution of an organic strong base DBU, a good solvent DMF of PVDF, and a poor solvent of PVDF, the dehydrofluorination treatment is carried out to obtain PVDF. After the carbon precursor film is carbonized, a PVDF-based carbon porous film having a plurality of mesopores is obtained, and the PVDF-based carbon porous film can also be used as the carbon porous film of the present embodiment.

Further, Reference H describes a compromise method (Method AB) of Method A and Method B, and the method can also be applied to this embodiment. That is, as in the manufacturing step of the carbon porous film shown in FIG. 5, the step AB1 uses a vinyl chloride resin (PVC resin) having a different number average molecular weight M as a carbonaceous raw material, and dissolves the PVC resin powder in DMF. DBU was added dropwise to the solution at room temperature to partially dehydrate the PVC resin, and a viscous coating liquid AB comprising PVC, DMF and DBU 3 components was prepared.

Then, in step AB2, the coating liquid AB is applied and formed on the release film or the release substrate so that the film thickness after carbonization is 100 nm to 63 μm. At this time, the coating film is surrounded by the periphery of the release film or the release substrate, and the film is not coated from the release film or the release substrate. The method of flowing out around is sealed by evaporation of solvent (water) and the composition of the coating liquid is changed or the area of the pores of the membrane is not disintegrated, and then heated at room temperature to 70 ° C to form a gel. A PVC-based gel film was obtained.

Step AB3: After peeling off the PVC-based gel film from the release film or the release substrate, the DMF in the gel is directly replaced by liquid CO ₂ , and then CO ₂ supercritical drying is performed to scatter the solvent to obtain a porous PVC system. Aerogel film.

Finally, step AB4 can be thermally stabilized in air (at O ₂ ) and at 150 to 250 ° C to thermally stabilize the PVC-based aerogel film, or to condense the PVC with iodine (I ₂ ) vapor. After the film is thermally stabilized at 150 to 250 ° C, it is heated to 700 ° C to 3500 ° C in an inert atmosphere or a nitrogen atmosphere in the same manner as the PVDC carbon porous film or the PVDF carbon porous film (here, 1000). °C) Carbonization was carried out to obtain a carbon porous film obtained by a PVC-based carbon aerogel.

If the PVC aerogel film is directly heated in the step AB4, the PVC aerogel film is melted, and the pore structure thereof is disintegrated, so that it is different from the case where the chlorinated PVC resin or the PVDC resin is used as the carbonaceous raw material, and it is necessary to borrow Immobilization of the pore structure by heat stabilization.

Fig. 8 of Reference H describes the pore distribution of a PVC-based carbon aerogel. According to Fig. 8, the dependence of the molecular weight M on the pore distribution and the dependence of the PVC concentration can be known.

Hereinafter, the weight percentage concentration of PVC in a solution including the components of PVC, DMF, and DBU3 when the carbon porous film of the present embodiment is assumed is obtained according to the representative experimental value described in the reference H and according to the method AB ( Wt% concentration, [PVC]), the number average molecular weight of the PVC (M), the molar ratio of the DBU molecule to the chlorine atom (Cl) in the PVC molecule (DBU/Cl), and the multivariate regression of the resulting structural parameters, Formula (47), formula (48). The apparent density ρ becomes 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, the dependency ratio of each factor was 66% for [PVC], 27% for M, and 7% for DBU/Cl.

Further, the pore radius r becomes r = -4.31 × ([PVC]) - 1.12 × (M × 10 ⁴ ) + 1.83 × (DBU / Cl) + 2.74 × 10 ¹ (48)

R ^*2 = 0.74, and the dependency ratio of each factor was 58% for [PVC], 32% for M, and 10% for DBU/Cl. Further, α corresponding to the pore radius r is obtained by doubling r and dividing by λ according to Formula 2.

The following cases are known from the formulas (47) and (48). As the [PVC] increases, the apparent density ρ becomes larger, and α corresponding to the pore radius r becomes smaller. On the other hand, as M increases, ρ becomes larger and α becomes smaller, and as DBU/Cl increases, ρ and α become larger. Therefore, in order to obtain larger pores, it is preferable to reduce [PVC], M as much as possible and to increase DBU/Cl as much as possible.

Further, in the case of approximating the second structural parameter group and the multi-regressive equation of T and Δ, that is, the cubic wall group pore model, if λ = 13.5 nm, the equations (33) and (34) are used, and if λ = At 6.75 nm, the equations (35) and (36) are used. In the case of the approximate cubic axis group pore model, if λ = 13.5 nm, the equations (37) and (38) are used, and if λ = 6.75 nm Then, using the formulas (39) and (40), the composition range of Ti, Δi, and Di satisfying the problem of the present embodiment can be known.

In the above manner, it is used in a molecular structure in which a structure is immobilized by a chemical reaction process or a carbonization process and a bubble is generated, and a chemical reaction or a carbonization reaction is performed, and bubbles or gaps generated in the processes are used as pores. Thus, a carbon porous film of the present embodiment which is a halogenated vinyl resin-based or vinylidene halide-based carbon porous film can be obtained.

2-2-3. Supplementary treatment

As a supplementary treatment shown in FIG. 5, after obtaining the carbon porous film of the present embodiment, one side of the surface of the carbon porous film is prevented in order to prevent oxidation and reduction of the carbon porous film by light from a high output light source of EUV. Or, on both sides, a predetermined number of Si, SiC, SiO ₂ , Si ₃ N ₄ , Y, Mo, Ru, Rh are coated by a known sputtering method, a vacuum deposition method, or the like within a range satisfying the target value of the problem of the present embodiment. Wait. The SiC film having a low extinction coefficient of EUV light and having a refractive index close to 1.0 and further reacting with carbon to form an excellent strength on the surface of the carbon film is preferably Si.

3. The film of this embodiment

Fig. 6 is a perspective view showing a protective film. Fig. 7 is a view showing a configuration of a cross section taken along line VII-VII in Fig. 6; The protective film 10 of the present embodiment is obtained by using the carbon porous film as the film for film 1 and using the film adhesive 2 on the frame 3 as shown in Fig. 6 . Further, a bonding means 4 with a mask adhesive (including a protective film) or a frame is applied to the back surface side of the mask of the protective film.

The frame 3 used in the present embodiment can be used for a general film, and a frame in which one or more vent holes 5 are provided on the side surface can be used. As the frame material, an Al-Zn-based aluminum alloy frame (a 7000-series aluminum alloy frame) in which Zn and Mg are added to an aluminum alloy to increase the strength is preferable. In order to suppress the stray light when the EUV light is irradiated to the frame, it is preferable to add the Al-Mg- which enhances the strength and corrosion resistance of the element Mg and Si which have a refractive index close to 1.0 and a low extinction coefficient k. Si-based aluminum alloy frame (6000 series aluminum alloy frame). Alternatively, a frame obtained by vapor-depositing the elements such as Si, SiC, Mg, or Zn on the surface of the aluminum alloy frame may be used.

As the masking adhesive 4, for example, an adhesive of a reaction product of an alkyl (meth) acrylate and a polyfunctional epoxy compound used for the ArF film described in Japanese Laid-Open Patent Publication No. 2011-107488 can be used. If the adhesive is irradiated with EUV light, there is a possibility that the component of the self-adhesive agent generates a decomposition gas. Therefore, when the frame is attached to the mask, the width of the frame 3 may not be narrower than the end of the frame width. Apply a mask adhesive. Moreover, as an aspect of the arrangement of the mask adhesive 4, as shown in FIG. 8(a), the mask adhesive 4 can be disposed in the groove 6 provided in the frame 3. At this time, the mask adhesive 4 is applied to the groove 6 slightly thicker than the depth of the groove 6. Further, as shown in FIG. 8(b), the mask adhesive may be placed on both sides of the groove 6 on which the mask adhesive 4 is disposed, so that the mask adhesive does not overflow from the frame of the frame. The slots 7, 8 are provided.

However, in general, the mask for EUV is often used again by peeling off the protective film, and the paste remaining in the mask for EUV is a problem. Therefore, as the bonding mechanism between the protective film 10 and the mask for EUV, it is more preferable to attach the core 11 of the ferromagnetic material such as iron Fe, cobalt Co, nickel Ni, etc. as shown in FIG. 9 instead of the mask adhesive. The electromagnet 13 having the conductive coil 12 (metal nanowire, carbon nanowire, etc.) is embedded in the groove 6 of the frame 3 or joined by an adhesive or the like, and is also provided on the mask side of the EUV. A strong magnet surface is used for electromagnetic bonding. Further, instead of providing the electromagnet 13 on the frame 3, an electromagnet may be provided on the mask side of the EUV, and a line of a strong magnet or the like may be provided in the groove of the frame.

Further, as a method of setting a strong magnet surface on an EUV mask which can be formed by alternately vapor-depositing Si and molybdenum (Mo) 40 layers or more on zero-expansion glass (LTE glass), A frame or sheet made of a ferromagnetic material such as a nickel-iron alloy film or an amorphous rare-earth iron-based alloy film is attached to the region of the mask next to the frame, or is formed by vacuum deposition, sputtering, or electrophoresis. A strong magnet film can be used.

The film adhesive 2 is preferably an inorganic-based adhesive which does not have an influence on the exposure when the decomposition gas is generated in a case where the bonding force is applied and the EUV light is irradiated. For example, an epoxy resin-based adhesive mixed with an inorganic material, for example, A-3/C-3 manufactured by Fujikura Kasei Co., Ltd. (an epoxy resin-based adhesive using carbon black in a filler), and an phenol mixed with an inorganic substance can be used. An adhesive, such as FC-403R manufactured by Fujikura Kasei Co., Ltd. XC-223 (a phenol resin-based adhesive using graphite as a filler) or an inorganic-based reactive adhesive such as a citrate-based, phosphate-based or colloidal lanthanum oxide.

Next, a method of manufacturing the protective film 10 will be described. First, the frame 3 to which the film adhesive 2 is applied in advance is placed next to the film 1 for a film of the present embodiment, and when the mask adhesive 4 is used, the frame 3 and the mask for the EUV are used. The mask adhesive 4 is applied to the side, and then a protective film is attached thereto, whereby the protective film 10 of the present embodiment can be obtained.

Furthermore, the bonding of the frame 3 and the EUV mask does not use an electromagnetic adhesive or the like. This is not required for the situation. The frame 3 for the frame 3 and the EUV mask can be attached to the frame 3 of the electromagnet 13 or the like.

[Industrial availability]

The present invention can preferably utilize a film for protecting a film and a film for protecting a photolithographic mask from contamination in the field of EUV photolithography.

Claims (9)

A film for a film which is composed of a carbon porous film, has a film thickness D of 100 nm to 63 μm, and a transmittance T of 84% or more when the extreme ultraviolet light having a wavelength of 13.5 nm passes through one time. The film for a film of claim 1, wherein the amount of scattering Δ caused by the pores of the carbon porous film is 10% or less when the ultraviolet light is passed once. The film for a film of claim 1 or 2, wherein the carbon porous body film has a pore diameter of 6.75 nm or more and 2430 nm or less. The film for a film according to claim 1 or 2, wherein in the carbon porous film, the apparent density obtained by dividing the mass by the volume is 1.0 × 10 ^-3 to 2.1 g/cm ³ . The film for a film according to claim 1 or 2, wherein the wavelength λ of the extreme ultraviolet light is set to 13.5 nm, the density W of the graphite is set to 2.25 g/cm ³ , and the apparent density of the carbon porous film (g) /cm ³ ) is ρ, and when the film thickness (nm) is D, the carbon porous body film has a structural parameter satisfying the following formula, α ≦ 30 (α: pore size parameter) 0.335 ≦ Nd ≦ 13 ( N: the number of pores in the film thickness direction (number), d: the wall thickness (nm) of the pores) αλ/d≦81 (λ: exposure wavelength (nm)), where N and d satisfy 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} }. The film for a film according to claim 1 or 2, wherein the wavelength λ of the extreme ultraviolet light is set to 13.5 nm, the density W of the graphite is set to 2.25 g/cm ³ , and the apparent density of the carbon porous film (g) /cm ³ ) is ρ, and when the film thickness (nm) is D, the carbon porous body film has a structural parameter satisfying the following formula, 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. A film for a film for a film according to any one of claims 1 to 6, and a frame for attaching the film for the film. The protective film according to claim 7, wherein the frame is provided with a groove on which a mask adhesive for bonding to the photolithography mask is disposed on a surface opposite to a surface on which the film for film is attached. The protective film of claim 7, wherein the frame is provided with an electromagnet for bonding to the photolithography mask on a surface opposite to the surface for supporting the film for the film.