JP3190981B2 - Dustproof cover for mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an object to prevent foreign substances from adhering to a transparent substrate (hereinafter, referred to as a mask) such as a photomask or a reticle used in a lithography process for manufacturing an LSI (Large Scale Integrated Circuit). The present invention relates to a dustproof cover for a mask (hereinafter, referred to as a pellicle) used as a mask. More specifically, the present invention relates to a pellicle having an antireflection layer made of a material having a low refractive index and having excellent solubility, film formability and adhesiveness.

[0002]

2. Description of the Related Art In semiconductor manufacturing, a semiconductor manufacturing apparatus such as a stepper (reduction projection exposure apparatus) is used for forming an integrated circuit pattern. What is important here is the quality of a mask serving as an original for forming a circuit pattern. In recent years, with the development of large-scale integrated circuits, the image line width of integrated circuits has become extremely fine. This trend is expected to continue in the future, and the quality of the mask is greatly affecting the yield and manufacturing cost of semiconductors. In particular, it is a serious problem that foreign matter adhering to the mask lowers the yield.

As one of the means for solving this problem, a method of mounting a so-called pellicle to protect the mask from foreign substances has been adopted (for example, Japanese Patent Publication No. 54-28716).
Reference). The pellicle is generally composed of a frame, a transparent film adhered to one side of the frame, and an adhesive adhered to the other side of the frame, and is attached to the mask by the adhesive. By attaching the pellicle to the mask, foreign matter (dust) can be prevented from adhering to the mask surface, but even if foreign matter adheres to the pellicle, the foreign matter is separated from the mask surface by the height of the frame. Foreign matter does not focus and has no effect on the integrated circuit pattern image.

Although the pellicle has the above advantages, it is required that the pellicle itself be free of foreign matter.
In particular, if foreign matter is attached to the inner surface of the pellicle, the foreign matter may fall and adhere to the mask surface during or after attachment to the mask. Therefore, it is necessary to remove foreign matter before mounting. This method includes a contact method and a non-contact method, but an air blow method in which foreign matter is blown off with air is generally used because the pellicle film surface is hardly damaged.

[0005] On the other hand, large-scale integrated circuits are increasingly being produced in small quantities and in many types. This means that a large number of masks are used, and the necessity of storing and managing the masks is increasing. At that time, it has been recognized that storage with a pellicle attached thereto is simple in management of foreign substances. As is clear from the purpose of use, the pellicle must firstly have high light transmittance. When the light transmittance is low, a longer exposure time is required to obtain a desired exposure amount, and the productivity of the process is lowered.

Heretofore, pellicles having at least one of a nitrocellulose single-layer thin film and a single-layer film provided with an antireflection layer have been used. When providing the anti-reflection layer, the optimum antireflection conditions, when the refractive index of the central layer in the case of the antireflection layer is one layer and n, the refractive index of the antireflection layer and the n ₁ n
It is indicated as ^1/2 = n _1. That is, when the square root of the refractive index of the center layer material is equal to the refractive index of the antireflection layer, the antireflection effect is maximized.

When the center layer material is a cellulose derivative, n
Is approximately 1.5, so that n ^1/2 = 1.22. A material having a refractive index close to 1.22 is excellent as a material for the antireflection layer. However, organic materials having a refractive index close to 1.22 are rare. Here, a layer made of a material having a refractive index of 1.36 or less is called a low refractive index layer, and a layer made of a material having a refractive index larger than 1.36 is called a high refractive index layer.

As a material having a low refractive index and high transparency, which is considered to be useful as an antireflection layer material of a pellicle,
Cytop (registered trademark) having a refractive index of 1.34 (manufactured by Asahi Glass Co., Ltd., JP-A-63-260932) and Teflon (registered trademark) AF (D) having a refractive index of 1.31 and 1.29.
A perfluorovinyl polymer having a cyclic structure in the main chain, as described in U.S. Pat. No. 3,170,901). The structural formulas of CYTOP (registered trademark) and Teflon (registered trademark) AF are shown below.

CYTOP (registered trademark)

[0010]

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Teflon (registered trademark) AF

[0012]

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However, Teflon (registered trademark) AF, which is most preferable in terms of refractive index, is poorly soluble in a solvent, and the solution is passed through a filter having a pore size of 0.2 μm, which is necessary for removing dust from the polymer solution. There was a drawback that filtration was not possible. In addition, even if used without filtration, because of insufficient solubility, when a film is formed by a spin coating method, color unevenness of the film occurs, or light is contained due to the inclusion of polymer fine particles that cause scattering. There were problems such as low permeability.

Further, a transparent thin film (hereinafter, referred to as a central layer) is made of a perfluorovinyl polymer such as Teflon (registered trademark) AF or Cytop (registered trademark) as a low refractive index layer.
When coated on the upper layer or on the high refractive index layer formed on the center layer, the adhesion between the center layer and the low refractive index layer or between the high refractive index layer and the low refractive index layer is low, and foreign matter on the pellicle surface is blown by air. There is a problem that the low-refractive-index layer is easily peeled off from the lower layer when it is removed by the above method. Furthermore, in the process of manufacturing the pellicle by attaching the laminated film to the frame,
There is also a disadvantage that the pellicle is easily peeled off from the frame due to the low adhesiveness of the low refractive index layer.

[0015]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-performance pellicle which solves the problem of the pellicle using the above-mentioned perfluorovinyl polymer as a low refractive index layer material.

[0016]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, have used a fluoropolymer having a specific substituent as a low refractive index layer material for an antireflection layer. As a result, they have found that the above problems can be solved, and have completed the present invention. That is, in the present invention, at least one surface of the transparent thin film comprises a low refractive index layer.
In a dustproof cover for a mask in which two antireflection layers are formed by laminating a low refractive index layer on a layer of an antireflection layer or a high refractive index layer, the low refractive index layer forming the antireflection layer is The present invention relates to a dustproof cover for a mask, comprising an amorphous perfluoropolymer having a carbonyl-containing group in a chain. Furthermore, the present invention relates to a dustproof cover for a mask, wherein the amorphous perfluoropolymer having a carbonyl-containing group in a side chain in the dustproof cover for a mask is a polymer represented by the following formula (1).

[0017]

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(Where Rfo represents a perfluoroether unit of the formula (2). R ₁ represents a perfluoroalkyl group having 1 to 15 carbon atoms or a partially substituted product thereof, a vinyl group,
Represents a perfluoroether group having 2 to 50 carbon atoms or a partially substituted product thereof. Further, the terminal of R ₁ may be linked to another triazine ring to form a network polymer. m ₁ 0
Or a positive integer, m ₂ is a positive integer, and m ₂ / (m ₁ +
m ₂ ) = 0.001 to 1.0. Rfo and R ₁ are the same as in formula (3). R ₂ represents a perfluoroalkylene group having 1 to 10 carbon atoms, a divalent perfluoroether group having 2 to 30 carbon atoms, or a single bond. X is OR _a , NR _b R
_c , R _a , R _b , and R _c are a hydrogen atom or a carbon atom
Represents 10 hydrocarbon groups. )

[0019]

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(Where t = 1, 2, 3, or 4, s =
1, 2 or 3, Z represents a perfluoroalkylene group having 2 to 20 carbon atoms or a perfluoroether group having 4 to 25 carbon atoms. n ₁ = 0 or 1, n ₂ = 1 to 300, (C _t F
Sequence of _2t O) units and (ZO) units can be arbitrarily selected. Hereinafter, the present invention will be described in detail.

In the present invention, as described above, a layer made of a material having a refractive index of 1.36 or less is called a low refractive index layer, and a layer made of a material having a refractive index larger than 1.36 is called a high refractive index layer. I do. The amorphous perfluoropolymer having a carbonyl-containing group in a side chain used in the present invention means a polymer having a carbonyl-containing group in a side chain and a main component of a main chain having an amorphous perfluoro structure. Specifically, for example, a polymer having a perfluoropolyether chain as a main component of the main chain and having a carbonyl-containing group as a pendant group, Teflon (registered trademark) AF
And a polymer having a structure in which a carbonyl-containing group is bonded as a pendant group to a perfluorovinyl polymer having a cyclic structure in the main chain such as CYTOP (registered trademark).

All of these amorphous perfluoropolymers having a carbonyl-containing group in the side chain have high adhesiveness and are useful as a material for a low refractive index layer of a pellicle. Among them, the polymer, particularly the polymer represented by the above formula (1), not only has excellent adhesiveness, but also has a low refractive index, excellent solubility, film formability, light resistance, and low pellicle properties. It is extremely useful as a refractive index layer material.

The carbonyl-containing group in the polymer used as the material for the low refractive index layer of the present invention is not particularly limited, but specific examples include a carboxyl group, an ester group, an amide group, and a ketone group. Although the molecular weight of the perfluoro unit Rfo represented by the formula (2) is not particularly limited, the number average molecular weight is usually in a range of 300 to 6 × 10 ⁴ ,
Preferably in the range of 1,000 to 2 × 10 ^4, more preferably used is in the range of 1,500-1 × 10 ^4. R
If the molecular weight of fo is too small, a polymer having a low refractive index cannot be obtained. On the other hand, if it is too large, it is difficult to synthesize and the adhesion is deteriorated, so that it is not practical.

The structure of Rfo of the polymer is preferably represented by the following formula (2-1), formula (2-2) or formula (2-3), but is not limited thereto. .

[0025]

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(Where A is a divalent residue of a perfluoroalkylene group having 2 to 20 carbon atoms or a perfluoroether having 4 to 25 carbon atoms, or a substituted product thereof.
n is 0 or a positive integer, and m + n is usually from 0 to 30.
0, preferably 4 to 300, more preferably 4 to 100
Range. )

[0027]

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(Where A 'is a divalent residue of a perfluoroalkylene group having 1 to 19 carbon atoms or a perfluoroether having 3 to 24 carbon atoms, or a substituted product thereof.
Is 0 or a positive integer, and is usually in the range of 1 to 300, preferably 4 to 300, and more preferably 4 to 100. )

[0029]

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(Where Rf is a divalent residue of a perfluoroalkylene group having 2 to 20 carbon atoms or a perfluoroether having 4 to 20 carbon atoms. A, b, c, d and e are 0 or positive A + b + c + d + e is usually 2 to 30
0, preferably 4 to 100, and more preferably 4 to 80. f is 0 or 1, and g is 1, 2 or 3. D and E are respectively D = F, E = CF ₃ or D
= CF ₃ , E = F. The arrangement of each unit represented by the following formula 10 can be arbitrarily selected. )

[0031]

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The polymer of the formula (1) used in the present invention can be synthesized by various methods.
No. -14169, Japanese Patent Publication No. 62-14171,
JP-A-57-175185, JP-B-53-536
No. 0, Canadian Patent No. 960222, etc., a bifunctional perfluoro group having a functional group such as a carboxyl group, an acid fluoride group, an ester group, an amide group, a nitrile group, an amidine group at both ends. It is synthesized using a polyether oligomer as a raw material. More specifically, the polymer of the formula (1) is prepared by using the bifunctional oligomer as a raw material, in EP 0422231, JP-A No. 2-20
It is synthesized by the method described in JP-A No. 2919 or JP-A-4-85328.

That is, the polymer of the above formula (1) is as follows:
The polymer represented by the formula (3) and R₁COY (where Y is
Represents F, Cl or Br. ) And (R₁CO)_TwoO (here
In R ₁Is a perfluoroalkyl group having 1 to 15 carbon atoms or
Partially substituted product, vinyl group, C2-50 perful
Represents an oloether group or a partially substituted product thereof. Reeds such as
(Hereinafter referred to as acylating agent I) and the following formula
(4) or an acylating agent represented by the following formula (5) (hereinafter, acylation)
Agent II. ) Is reacted.

[0034]

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(Where Rfo represents a perfluoroether unit of the formula (2))

[0036]

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[0037] (wherein R ₂ is the same as R ₂ of formula (1).)

[0038]

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(Where Y 'represents F, Cl or Br) When the compound represented by the above formula (4) among the acylating agents II is used, in the formula (1), X = OH A polymer is obtained. From the above, acylating agent I and acylating agent I
The acylation reaction of the polymer of the above formula (3) with any combination of I gives a polymer of the formula (1) having an arbitrary structure and an arbitrary -COX group content.

In the formula (1), the -COX group content is defined as m
_When expressed as ₂ / (m ₁ + m ₂ ), it is usually 0.001 to
1, preferably in the range of 0.005 to 0.8, more preferably 0.01 to 0.5. This value is 0.0
If it is less than 01, the adhesiveness is not sufficient, which is not preferable. R
₁ COY (where Y represents F, Cl or Br) or (R ₁ CO) ₂ O (where R ₁ is a perfluoroalkyl group having 1 to 15 carbon atoms or a partially substituted product thereof, a vinyl group, a carbon specific examples of the acylating agent I represented by represents.) perfluoroether group or a partially substituted compound having _{2~50, CF 3 COCl, CF 3} CF 2 CF 2 COF, CF
₃ (CF ₂ ) ₅ COCl, CH ₂ ＣＨCHCOCl, (C
Examples thereof include F ₃ CO) ₂ O, (CF ₃ CF ₂ CF ₂ CO) ₂ O, and compounds represented by the following formula (6).

[0041]

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When R ₁ is a partially substituted product of a perfluoroalkyl group or a perfluoroether group, the partially substituted product refers to a part of the fluorine atom in the perfluoroalkyl group or the perfluoroether group, 35 atoms
% Or less, preferably 20% or less, substituted with a halogen atom other than a hydrogen atom and / or a fluorine atom.

On the other hand, specific examples of the acylating agent II include:
Compounds represented by the following formulas (7) to (13) are exemplified.

[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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[0049]

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[0050]

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In the equation (1), X = OR '(R'
Represents a lower alkyl group. ) After synthesis, X = O by hydrolysis or reaction with HNR _b R _c
It may be converted to a polymer of H or NR _b R _c . The polymer comprising the repeating unit represented by the formula (1) used in the pellicle of the present invention can be prepared by adjusting the amount of the acylating agent to obtain a triazine ring, that is, a repeating unit of the formula (1) and an imidoylamidine. A polymer is obtained which contains both groups, i.e. repeating units of the formula (3), which can also be used as the low refractive index layer according to the invention.

The molecular weight of the polymer comprising the repeating unit represented by the formula (1) is not particularly limited as long as the polymer does not show fluidity under the conditions of use of the pellicle. However, from the viewpoint of durability and operability of the pellicle, the viscosity of the polymer or the viscosity of the polymer of the formula (3) as a raw material of the polymer is 0.15 at 40 ° C.
dl / g or more, preferably 0.20 dl / g or more, more preferably 0.30 dl / g or more is used.

Since the polymer used in the pellicle of the present invention is easily dissolved in various fluorine-based solvents or mixed solvents containing a fluorine-based solvent, a pellicle film in which the polymer is laminated can be easily prepared using the solution. it can. The solvent of the polymer used in the present invention is 1,1,2-trichloro-1,2,2-trifluoroethane (R-113).
Chlorofluorocarbon solvents such as perfluorohexane and perfluorooctane; perfluoro-2-butyltetrahydrofuran; 2H-tetradecafluoro-5- (trifluoromethyl) -3,6- Fluorinated ether solvents such as dioxanonane, or tri (perfluoro-n-
A fluorinated solvent such as a perfluoroamine solvent such as butyl) amine, or a mixed solvent of the above fluorinated solvent and a polar solvent such as an ether solvent can be used.

One of the features of the polymer used in the present invention is that the refractive index is low. Among them, those having a refractive index (n _D ) in the range of 1.28 to 1.36 are low refractive indexes of the pellicle. Useful as a material, preferably 1.29
To 1.34, more preferably 1.29 to 1.32. The material constituting the central layer of the pellicle of the present invention is required to be excellent in transparency and strength, and to have high stability to a light source to be used, for example, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate. And cellulose derivatives such as ethyl cellulose and cellulose derivatives described in JP-A-2-294645. Each of these cellulose derivatives is used alone or as a mixture of two or more types, and a mixture of two or more types is preferable. Further, nitrocellulose having excellent film strength and shape retention under high humidity and cellulose acetate having excellent weather resistance are provided. Preferred is a mixture of cellulose derivatives other than nitrocellulose, such as cellulose acetate butyrate and cellulose acetate propionate. The content of nitrocellulose in the mixture is preferably from 10 to 50% by weight, and more preferably from 20 to 40% by weight in consideration of the balance between film strength, shape retention under high humidity, and weather resistance. When the content of nitrocellulose is less than 10% by weight, the weather resistance of the film is inferior, and when it exceeds 50% by weight, the film strength is remarkably reduced.

The higher the molecular weight of the cellulose derivative, the better the shape retention of the membrane. Therefore, the number average molecular weight is preferably 30,000 or more, more preferably 50,000 or more. Among the above cellulose derivatives, commercially available nitrocellulose can be easily obtained from Asahi Kasei Kogyo Co., Ltd., and cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate can be easily obtained from Eastman Kodak Co., Ltd.

As the solvent for the cellulose derivative, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as butyl acetate, isobutyl acetate, ethyl lactate and cellosolve, and a mixed solvent of two or more of these are used. Is done. As the film forming method of the center layer of the present invention, various film forming methods usually used such as a melting method and a casting method can be applied. For example, in the case of a non-thermoplastic material such as nitrocellulose, a method of casting in a solution is usually used. In the pellicle of the present invention, uniformity of the film thickness is important. As a method for producing a thin film having a uniform thickness, a spin coating method (spin coater method), a knife coater method, an immersion pulling method, a casting method on a fluid surface, and the like. Is suitable, and among them, the spin coater method is preferable. However, the spin coating conditions for obtaining the thin film of the present invention are affected by many factors such as the viscosity of the solution, the evaporation rate of the solvent from the solution, the temperature around the spin coater, the humidity, the spin speed, and the spin time. You need to make the right choice.

The thickness of the pellicle of the present invention is not particularly limited, but is preferably 0.2 to 10 μm, and more preferably 0.5 to 8 μm. A method for manufacturing a three-layer film will be described below. First, a solvent is volatilized from a thin film of a center layer material formed on a smooth substrate by spin coating using a hot plate, an oven, or the like. On the thin film after drying, a solution prepared to a predetermined concentration of the above-mentioned fluoropolymer is applied by a spin coater method or the like, and dried to form a thin film of the fluoropolymer as an antireflection layer to form a two-layer film. . Subsequently, the two-layer film formed on the smooth substrate is peeled off by attaching a frame of metal or resin, inverted, spin-coated again with an antireflection layer, and a fluorine-containing polymer layer is formed on both sides of the center layer. A three-layer film is obtained.

The five-layer film can be manufactured in the same manner as described above, except that a high refractive index material is formed between the central layer and the antireflection layer of the three-layer film. When forming the anti-reflection layer of two layers, the refractive index of the central layer n, n ₁ the refractive index of the low refractive index layer of the antireflection layer, and the refractive index of the same height refractive index layer and n _2, The anti-reflection condition is represented by n ^1/2 = n ₂ / n ₁ . When the central layer is made of a cellulose derivative, n is approximately 1.5, so that n ₂ / n ₁ = 1.22 is the antireflection condition. For example, the preferred range of the refractive index of the fluoropolymer constituting the present invention is 1.28 to 1.36, and the corresponding refractive index of the high refractive index layer is 1.56 to 1.66. As the polymer material satisfying this condition, a vinyl aromatic polymer is preferable, and specific examples thereof include a homopolymer or a copolymer of styrene, a derivative of styrene, and vinyl naphthalene.

[0059]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention.

[0060]

[Synthesis Example 1] Example 4 of JP-A-2-202919
In the same manner as described above, a dinitrile oligomer represented by the following formula (14-1) (number average molecular weight: 5050, bifunctional purity: 99.9% or more) is converted to a polyimide yl represented by the following formula (14-2). Amidine was synthesized.

[0061]

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(M ′ and m ″ represent positive integers)

[0063]

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(M ′ and m ″ are the same as in the equation (14-1).
n 'represents a positive integer. ) This polyimideylamidine has an intrinsic viscosity of 0.4 in perfluorooctane at 40 ° C.
It was 70 dl / g.

[0065]

[Synthesis Example 2] Polyimide Ilamidine 5 obtained in Synthesis Example 1
g (1 mmol) was dissolved in 50 g of perfluorohexane, and 1.35 g of an acylating agent represented by the following formula (12) (10 mm
ol) was mixed with a solution of 20 g of Freon (registered trademark) -113, and the mixture was stirred and reacted at 40 ° C. for 17 hours.

[0066]

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After the completion of the reaction, excess chloroform was added.
The polymer was precipitated and purified. 3. Evaporate the solvent.
8 g of a clear, colorless polymer were obtained. Infrared of this polymer
Absorption spectrum is 1766cm^-1Attributable to the carbonyl group
Absorption and 1556cm ^-1Attributable to the triazine ring
And has a structure represented by the following formula (14-3).
It was confirmed that. The intrinsic viscosity is 0.50 dl / g,
The folding ratio was 1.31.

[0068]

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[0069]

Synthetic Example 3 The same polyimide yl amidine as in Synthetic Example 2 was reacted with perfluoroglutaric anhydride in a molar ratio of 0.40 times the number of moles of imidoylamidine groups in the polyimideylamidine, and By reacting with trifluoroacetic anhydride at a molar ratio of 20 times the ilamidine group, a perfluoropolytriazine having the structure of the following formula (14-4) was synthesized.

[0070]

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(M ′, m ″, n ″, n ″ ″ represent positive integers, and n ″ ″ / (n ″ + n ″ ″) = 0.4.) Perfluoropolytriazine was a colorless and transparent polymer having an absorption at 1,783 cm ^-1 attributable to a carboxyl group in its infrared absorption spectrum, and had a refractive index of 1.31.

[0072]

Example 1 Cellulose acetate propionate (CAP482-2 manufactured by Eastman Kodak Co., Ltd .: CAP
Abbreviated. A) a 7% by weight solution of ethyl cellosolve in
0.8 of polytriazine (refractive index 1.31) of Synthesis Example 2
Each of the wt.% Tri (perfluoro-n-butyl) amine solutions was prepared by filtration through a filter having a pore size of 0.1 μm. 20 ml of the prepared CAP solution was dropped on a silicon wafer set on a spin coater, and the wafer was placed in a 1.0-cm wafer.
After rotating at 00 rpm for 45 seconds, the solvent was evaporated on a hot plate, and a 1.9 μm thick CA was deposited on the wafer.
A P thin film was formed. Subsequently, 3 ml of the prepared polytriazine solution was dropped on the thin film, rotated at 600 rpm for 30 seconds, and air-dried to form a two-layer film.

Next, the two-layer film was peeled from the wafer, turned over, and set on a spin coater, and a polytriazine layer was formed in the same manner as described above to form a three-layer film. Observation of the three-layer pellicle with monochromatic light from a mercury lamp revealed that the surface was a good film having a smooth surface and no color unevenness. The light transmittance of this three-layer pellicle is 99.8% for g-line and 9 for i-line.
9.7%.

FIG. 1 shows the light transmittance of this three-layer film. This light transmission characteristic is preferable as a pellicle for a projection aligner that is exposed to light in the wavelength range of g-line to i-line.

[0075]

Example 2 Polytriazine of Synthesis Example 3 (refractive index 1.3
A three-layer film was formed in the same manner as in Example 1 except that the tri (perfluoro-n-butyl) amine solution of 1) was used.
Observation of the three-layer pellicle with monochromatic light from a mercury lamp revealed that the surface was a good film having a smooth surface and no color unevenness.

The light transmittance of the three-layer pellicle was 99.8% for g-line and i-line.

[0077]

[Comparative Example 1] Teflon (registered trademark) manufactured by DuPont
AF1600 (refractive index 1.31) was dissolved in tri (perfluoro-n-butyl) amine to form a 1.5% by weight solution. However, this solution was clogged with a filter having a pore size of 0.1 μm and could not be filtered.

This solution was used in the same manner as in Example 1 except that the solution was not filtered, but instead of the polytriazine solution of Example 1.
A layer pellicle was formed, but with monochromatic light from a mercury lamp, streak-like color unevenness running radially from the center of the film was observed.

[0079]

Example 3 Cellulose propionate (Aldric)
h company, hereinafter abbreviated as CP) 6 g and nitrocellulose (Asahi Kasei Kogyo Co., Ltd. HIG-20, nitrification degree 12.0%, hereinafter abbreviated as NC) 4 g were dissolved in ethyl acetate cellosolve to obtain a solid concentration of 7 g / The dl solution and the polytriazine solution used in Example 1 were each prepared by filtering with a filter having a pore size of 0.1 μm.

20 ml of the prepared CP / NC solution was dropped on a silicon wafer set on a spin coater, and the wafer was rotated at 950 rpm for 45 seconds. Then, the solvent was evaporated on a hot plate to form a film having a thickness of 1.9 μm on the wafer.
m CP / NC thin films were formed. Subsequently, 3 ml of the prepared polystyrene solution was dropped on this thin film, and 500 rpm
m and then air dried to form a two-layer film.

Further, 3 ml of the prepared polytriazine solution was dropped on the two-layer film, rotated at 600 rpm for 30 seconds, and air-dried to form a two-layer film. Next, the three-layer film was peeled off from the wafer, inverted, and set on a spin coater, and a polystyrene layer and a polytriazine layer were sequentially formed on the CP / NC film layer in the same manner as described above to form a five-layer film. .

The light transmittance of the five-layer pellicle was 99.6% for g-line and 99.7% for i-line. Also, g-line ~
The light transmittance was 99% or more in the range of the i-line.

[0083]

Example 4 A three-layer film was formed from the CP / NC solution prepared in Example 3 and the polytriazine solution prepared in Example 2 in the same manner as in Example 1. The light transmittance of this three-layer pellicle was 99.8% for g-line and i-line.

[0084]

Examples 5 and 6, Comparative Examples 2 and 3 Samples shown in FIG. 2 were prepared, and the degree of peel strength between the CP + NC blend film and the perfluoropolymer was examined. As the perfluoropolymer of FIG. 2, a polytriazine having a carboxyl group in the polymer chain of Synthesis Example 3 (Example 5), a polytriazine having an ester group in the polymer chain of Synthesis Example 2 (Example 6),
Cytop (registered trademark) CTX-809 (Asahi Glass Co., Ltd.)
Comparative Example 2), Teflon (registered trademark) AF-1600
(DuPont, Comparative Example 3).

Table 1 shows the results of the peeled state when the circular aluminum frame of the sample of FIG. 2 was pulled under a load of 20 gf.
Shown in According to this, it is understood that polytriazine having a carboxyl group in the polymer chain has much higher adhesiveness than perfluorovinyl polymers such as Cytop (registered trademark) and Teflon (registered trademark) AF.

[0086]

Example 7 and Comparative Example 4 Using the polytriazine of Synthesis Example 3 (Example 7) and CYTOP® CTX-809 (manufactured by Asahi Glass Co., Ltd., Comparative Example 4) as antireflection layer materials, An attempt was made to form a three-layer pellicle in the same manner as in Example 1. At that time, an operation of pressing a circular frame having an adhesive layer on the two-layer film in the same manner as in FIG. 2 and peeling the wafer from the wafer was performed. With the polytriazine of Synthesis Example 3, the two-layer film could be peeled. On the other hand, CYTOP (registered trademark) peeled off at the interface between CYTOP (registered trademark) and CAP.

The three-layer pellicle of Example 7 was a good film having a smooth surface and no color unevenness when observed with monochromatic light from a mercury lamp. The light transmittance of this three-layer pellicle was 99.8% for both g-line and i-line.

[0088]

[Table 1]

[0089]

The pellicle of the present invention has a high light transmittance by using a low refractive index fluoropolymer having high transparency and excellent solubility and adhesiveness as a low refractive index layer component of an antireflection layer. It is a pellicle that has high air resistance and excellent air blow resistance and operability.

[Brief description of the drawings]

FIG. 1 is a graph showing the light transmittance of a pellicle of Example 1.

FIG. 2 is an explanatory view showing the structure of a peel strength evaluation sample of Example 5, Example 6, Comparative Example 2, and Comparative Example 3.

[Explanation of symbols]

 Reference Signs List 1 aluminum frame 2 adhesive 3 perfluoropolymer (0.1 μm) 4 CN + NC blend film (10 μm) 5 silicon wafer

Claims (2)

(57) [Claims] 1. An anti-reflection layer comprising a low-refractive-index layer or a low-refractive-index layer laminated on a high-refractive-index layer is formed on at least one surface of a transparent thin film body. The dustproof cover for a mask according to claim 1, wherein the low refractive index layer forming the antireflection layer is made of an amorphous perfluoropolymer having a carbonyl-containing group in a side chain. 2. An amole having a carbonyl-containing group in a side chain.
A fast perfluoropolymer represented by the following formula (1)
The dustproof cover for a mask according to claim 1, which is a polymer. Embedded image(Where Rfo is a perfluoroether unit of the formula (2)
Represents a knit. R₁Is a perfluoroa having 1 to 15 carbon atoms
Alkyl group or partially substituted product thereof, vinyl group, 2 to 5 carbon atoms
0 represents a perfluoroether group or a partially substituted product thereof.
You. Also, R₁Is linked to the other triazine ring
An eye structure polymer may be formed. m₁Is 0 or positive integer
Number, m_TwoIs a positive integer and m_Two/ (M₁+ M_Two) =
0.001 to 1.0. R_TwoIs a group having 1 to 10 carbon atoms.
-Fluoroalkylene group, divalent par having 2 to 30 carbon atoms
Represents a fluoroether group or a single bond. X is OR
_a, NR _bR_cAnd R_a, R_b, R_cIs a hydrogen atom or
Represents a hydrocarbon group having 1 to 10 carbon atoms. )(Where t = 1, 2, 3, or 4, s = 1, 2, or 3,
Z is a perfluoroalkylene group having 2 to 20 carbon atoms or carbon
Represents a perfluoroether group having a prime number of 4 to 25. n₁=
0 or 1, n_Two= 1 to 300, (C_tF_2tO) units and
The arrangement of (ZO) units can be arbitrarily selected. )