JP2000162761A - Pellicle, its production and exposing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a pellicle having excellent light resistance in which reduction of the film thickness due to photolysis is suppressed, by satisfying specified conditions. SOLUTION: This pellicle satisfies the following conditions (a) to (c). (a) When the film is irradiated with ArF excimer laser beam (of the wavelength λat 193 nm) under the following conditions, the total dose of beam till the reduction of the film thickness reaches 5 nm is >=1420 J/cm2. The irradiation conditions of the ArF excimer laser beam are specified to 0.1 (mJ/cm2)/pulse pulse energy density, 100 Hz repetition frequency, 10 mm×10 mm irradiation area and an atmosphere of 20 L/min dry air flow rate. (b) The film consists of a fluorocarbon resin essentially comprising carbon and fluorine, or further with oxygen. (c) The film thickness ranges from 0.1 to 10 μm. Thereby, the obtd. pellicle has excellent transmittance especially for vacuum UV rays.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pellicle, a method for producing the pellicle, and an exposure method.
In particular, the present invention relates to a pellicle suitable for lithography using vacuum ultraviolet light and a method for producing the pellicle. The invention also relates to an exposure method using this particular pellicle.

[0002]

2. Description of the Related Art In a photolithography process, a photomask or reticle (hereinafter referred to as a "mask") in which a circuit pattern is formed on a glass plate surface with a vapor-deposited film of chrome or the like is used, and the circuit is formed on a silicon wafer coated with a resist. An operation of transferring the pattern by exposure is performed. In this step, if the exposure is performed in a state where foreign matter such as dust adheres to the circuit pattern on the mask, the foreign matter is also transferred to the wafer and becomes a defective product wafer. In particular,
When exposure is performed by a stepper, there is a high possibility that all chips formed on the wafer become defective, and adhesion of foreign matter to the circuit pattern of the mask becomes a serious problem.
Pellicles have been developed to solve this problem, and various improvements have been made.

In general, a pellicle is formed by stretching a transparent film made of a resin such as nitrocellulose on one side of a pellicle frame made of aluminum or the like, and applying a mask to the other side by applying an adhesive or the like. It can be mounted on top. According to this, it is possible to prevent foreign matter from entering from the outside, and even if foreign matter might adhere to the film, the problem is unlikely to occur because the image is transferred out of focus at the time of exposure.

In the semiconductor process, the wavelength of an exposure light source is being shortened in order to improve the degree of integration by miniaturizing a pattern. After the KrF excimer laser (λ = 248 nm), which is currently on the market, vacuum ultraviolet light is used. Range (λ ≦ 2
00 nm), among which the ArF excimer laser (λ = 193 nm) is considered the most promising.

On the other hand, as the wavelength of the light source becomes shorter, the photon energy increases. For example, an ArF excimer laser has an energy of 6.4 eV (= 147 kcal / mol). This energy is the dissociation energy of the C—C bond in the organic polymer (104 kcal / mo).
Since it is sufficiently larger than 1), a polymer having absorption at the wavelength of the exposure light source easily undergoes photodecomposition by exposure light irradiation and cannot be used as a pellicle film material. Therefore, from KrF lithography, a fluoropolymer having relatively low absorption in the deep ultraviolet region, for example, a commercially available fluororesin Cytop (CYTOP, trade name of Asahi Glass Co., Ltd.) or a fluororesin Teflon AF (trade name of DuPont, USA) ) Is used.

[0006]

However, even with these fluoropolymers, light absorption occurs in the vacuum ultraviolet region,
There is a problem that the film thickness is reduced by photolysis. For example, fluorine-containing resin Cytop (film thickness 1μ)
m), the oscillation wavelength of the ArF excimer laser is 193n.
m had an absorption of about 1%, and the light resistance was remarkably short as compared with the time of KrF excimer laser irradiation.

Accordingly, an object of the present invention is to provide a pellicle which has excellent transparency to ultraviolet light, particularly vacuum ultraviolet light, suppresses the tendency of the film thickness to decrease due to photolysis, and as a result has excellent light resistance and a method for producing the same. To provide. Another object of the present invention is to reduce the light resistance due to photodecomposition of a pellicle even when ultraviolet light, particularly vacuum ultraviolet light, is used, and as a result, a sharp and fine pattern can be formed for a relatively long time by lithography. An object of the present invention is to provide an exposure method which can be formed over the entire surface.

[0008]

According to the present invention, an organic polymer is treated to remove trace metal components and / or high molecular weight components and / or incomplete molecular structural components contained in the organic polymer. The pellicle film is characterized in that the impurity-removed organic polymer obtained as described above is used as a material for the pellicle film. According to the present invention, there is also provided an impurity obtained by removing at least a part, preferably a main part, of at least one of a trace metal component and / or a high molecular weight component and / or an incomplete molecular structure component contained in an organic polymer. The method for producing a pellicle membrane is provided, wherein the operation of obtaining the removed organic polymer is performed using a filter having an adsorption effect by a zeta potential.

According to the present invention, there is further provided a pellicle film characterized in that the content of each trace metal component in the impurity-removed organic polymer is 1 ppm or less. In the present invention, the organic polymer is a fluororesin containing carbon (C) and fluorine (F) as main components, particularly a fluorine resin containing only carbon (C), fluorine (F) and oxygen (O) as components. It is preferably a resin. According to the present invention, further, the pellicle film has a wavelength of 140 to 200 nm.
An exposure method is provided for use in lithography using an ultraviolet exposure light source in the range of (1).

Further, as an aspect of the present invention, a fluororesin containing carbon (C) and fluorine (F) as main components, particularly only carbon (C), fluorine (F) and oxygen (O) as components. There is a pellicle film characterized by using a fluororesin which is treated with a soluble solvent thereof.
As the fluororesin treated with the soluble solvent, it is preferable to use the fluororesin that has been separated from a part of the fluororesin dissolved from the solution of the soluble solvent of the fluororesin as it is and / or precipitated. . One preferred embodiment of the fluororesin thus obtained is one in which the content of the square metal component is 1 ppm or less. Further, the fluororesin used in this embodiment is treated with a soluble solvent to form at least one of at least one of a trace metal component, a high molecular weight component and an incomplete molecular structure component of the fluororesin. It is preferable that the part is removed.

Pellicle membrane obtained by the above various embodiments
Is used for lithography using ultraviolet light as the exposure light source.
Even when used, photodecomposition is suppressed, and durability that is not seen in the past
A pellicle film with high performance is obtained. That is, other than the present invention
The embodiment of the present invention provides a novel pellicle membrane,
Characterized in that the above conditions (a) to (c) are simultaneously provided.
A pellicle film is provided. (A) ArF excimer laser light (wavelength λ = 193 nm)
(Nm) under the following conditions:
Total illumination until the thickness reduction reaches 5 nanometers (nm)
Radiation is 1420 Joules / square centimeter (J / c
m²) Or more, preferably 1420 to 28400
Joules / square centimeter (J / cm ²), Especially
Particularly preferably, 1420 to 14200 joules / square
Centimeter (J / cm²). ArF excimer laser light irradiation conditions Pulse energy density: 0.1 (mJ / cm²) / Pulse Repetition frequency: 100 Hz Irradiation area: 10 mm × 10 mm Atmosphere: dry air 20 liter (L) / min (min) Flow (b) Carbon (C) and fluorine (F) or further oxygen (O)
Is a fluororesin whose main component is (C) Thickness of 0.1 to 10 micrometer (μm)
It is.

[0012]

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, the removal of trace metal components, high molecular weight components, and incomplete molecular structural components from the organic polymer constituting the pellicle film can be achieved by absorbing ultraviolet light, particularly vacuum ultraviolet light, from the pellicle film. And is effective in reducing the decrease in film thickness due to photolysis. Furthermore, the present invention is based on the discovery of a pellicle film having excellent light resistance, which has not been seen before, by treating a fluororesin constituting the pellicle film with a soluble solvent.

The present inventors have found that the following formula (1)

[0014]

Embedded image With respect to the fluororesin having the molecular structure represented by the formula (Cytop), the absorption wavelength calculation corresponding to the molecular structure was performed by using the molecular orbital method. As a result of this calculation, the vacuum ultraviolet spectral absorption curve shown in FIG.
It was found that there was no absorption at 93 nm.

However, in the case of an actual fluororesin, as already pointed out, absorption of about 1% occurs at a thickness of 1 μm, and light resistance is deteriorated due to a decrease in film thickness. This fact is
It becomes immediately apparent by referring to the examples and comparative examples described below.

The present inventors have conducted intensive studies on the cause of this difference, and as a result, have found that the cause is caused by impurities (trace metals, etc.) contained in the polymer. And filtered.
When the impurities were removed or the impurities were removed by treatment with a soluble solvent, a remarkable improvement in light resistance was confirmed.

Please refer to FIG. 2 of the accompanying drawings. FIG. 2 shows a fluorine resin without the impurity removal treatment (（), a fluorine resin with the impurity removal treatment performed by a filter having an adsorption function by zeta potential (●), and an impurity removal treatment by a soluble solvent treatment. The relationship between the total irradiation dose (J / cm ² ) and the thickness reduction (nm) is plotted for the fluororesin (▲) irradiated with an ArF excimer laser having a wavelength of 193 nm. According to these results, it is understood that removing trace metals and the like in the organic polymer is effective in suppressing a decrease in light resistance due to a decrease in film thickness.

In the present invention, the problem of a decrease in light resistance due to a decrease in film thickness is caused by the following reason. That is, it is generally known that the transmittance of light having a specific wavelength varies depending on the film thickness, and the transmittance curve for the film thickness draws a sine curve. Therefore, even if the pellicle film is set to a constant thickness so that the highest transmittance is obtained for a certain wavelength of light, the transmittance decreases as the film thickness itself decreases, resulting in deterioration of the pellicle film. It is connected. In this sense, it will be apparent that it is important to suppress the decrease in the thickness of the pellicle film for vacuum ultraviolet light as much as possible in order to extend the life (light resistance).

The organic polymer used for the pellicle film cannot avoid the incorporation of trace metal components due to the resin production process and the like. Examples of the trace metal component include an alkali metal component such as sodium, an alkaline earth metal component such as calcium, iron, cobalt, nickel and the like in the Periodic Table 8 of the container, apparatus, or resin production raw materials or auxiliary materials. Group 4 metal components of the periodic table such as silicon and silicon. Generally, the amount of this trace metal component reaches 3 ppm or more. In the impurity-removed organic polymer used in the present invention, each trace metal component is removed so that the amount thereof is 1 ppm or less, from the viewpoint of light resistance. When the amount of each trace metal component exceeds the above range, the absorption of vacuum ultraviolet light in the organic polymer constituting the pellicle film becomes non-negligible, and the light resistance is considerably inferior to those in the above range. Become like

Further, as a component which causes nonuniformity of the pellicle film and thereby impairs the light transmittance of the film, it is considered that a high molecular weight component of the organic polymer exists.
These high molecular weight components are inferior in solubility in a solvent as compared with other resin components, and it is considered that their presence in the film causes non-uniformity in the structure of the film. By removing the high molecular weight component, the uniformity of the film is improved, and the light transmittance is improved. As shown in an example to be described later, in the resin in the solution treated with the filter having the adsorption effect by the zeta potential, the intrinsic viscosity is lower than that of the untreated resin, and the high molecular weight component is removed. It is confirmed that. Above all, the degree of reduction of the intrinsic viscosity ([η]) is 3% or more, usually 3% to 60%, based on the raw resin solution.
%, Especially 5% or more, and particularly preferably 5% to 50%
If it has decreased, it can be determined that the removal of the high molecular weight component is sufficient.

Further, in the pellicle film of the present invention, a fluorine-containing organic polymer is used as a material. In the molecules constituting the organic polymer, for example, a double bond remains or the ratio of fluorine is relatively low. It is considered that the incomplete molecular structural component, which is an extremely small component, causes photodecomposition due to exposure light irradiation, thereby causing a reduction in film thickness and inhibiting light resistance. Therefore, in the present invention, light resistance is improved by removing such incomplete molecular structural components from the organic polymer.

In the present invention, at least a part of impurities such as trace metals, high molecular weight components and incomplete molecular structure components contained in the organic polymer adsorb the organic polymer by zeta potential prior to film formation. Or by treating with a soluble solvent.

The zeta (ζ) potential is also called an electrokinetic potential. When a solid (dispersion phase) and a liquid (dispersion medium) that are in contact with each other perform relative motion, a potential difference generated at the interface between the two. Is defined as In general, an electric double layer is formed at the interface between a solid and a liquid. In this electric double layer, a portion close to the solid has a stationary phase (or adsorption layer). ing.
When the solid and the liquid make a relative motion, the stationary phase moves together with the solid. Therefore, the potential difference that actually governs the motion is considered to be the potential difference between the stationary phase surface and the inside of the solution (diffusion phase). As for the charging of the dispersed phase, it is said that when the dielectric constant of the dispersing medium is different from that of the dispersing phase, the larger the dielectric constant is positively charged, and the smaller the dielectric constant is negatively charged.

In general, for the same (same charged) colloid particles dispersed in an organic polymer solution, the zeta (ζ) potential and van der Waals (van der
Waals), the former acting as a repulsive force and the latter acting as a suction force. If the potential energy for the colloid particles is taken on the vertical axis, the distance between the colloid particles is taken on the horizontal axis, and the repulsive force acts above the origin 0 and the suction force acts below the origin, conceptually, Is considered to be in the state shown in FIG. That is, when the colloid particles approach each other from a sufficiently distant position, the barrier (B) due to the zeta potential is present, so that the particles can be prevented from further approaching each other and the colloid particles are stably present without agglomeration. It is thought to be.

On the other hand, when filtration is carried out using a filter having an adsorbing action by the zeta potential, the adsorbing action of the colloid particles charged opposite to the zeta potential of the filter and the double collection by mechanical filtration are performed. By action
This effectively removes colloid particles. Further, in the case of a fluororesin containing carbon (C) and fluorine (F) as main constituent components, the operation of removing the trace metal component, the high molecular weight component and the incomplete molecular structure component includes the operation of removing the fluororesin. By the treatment with the soluble solvent, a fluororesin pellicle film having excellent light resistance, which has not been seen before, is obtained.

As a fluororesin treated with a soluble solvent,
A part of the fluororesin dissolved from the solution of the fluororesin soluble solvent is left as a solution and / or precipitated,
The fluororesin after separation is preferred. The component of the fluororesin that is separated and removed as a solution is usually 60% by weight or less, preferably 3 to 60% by weight, and more preferably 5 to 50% by weight.
% By weight is desirable. As the fluororesin thus obtained, for example, a fluororesin in which the content of each trace metal component is 1 ppm or less is preferable. In this case, it is preferable to use a fluorine resin from which at least one of the trace metal component, the high molecular weight component and the incomplete molecular structure component of the fluorine resin has been removed by treating with a soluble solvent.

In order to remove the high molecular weight component, in addition to the above-mentioned method using a filter having an adsorption effect by the zeta potential, a poor solvent is added to a solution of the fluororesin to precipitate the dissolved fluororesin. Separation is common. Thereby, it is desirable that the intrinsic viscosity (gram / deciliter) is reduced by 3% or more, usually about 5 to 50%, compared to the intrinsic viscosity (gram / deciliter) of the fluororesin before separation.

According to the present invention, the following conditions (a) to (a)
A pellicle membrane characterized by simultaneously providing (c)
Provided. (A) ArF excimer laser light (wavelength λ = 193 nm)
(Nm) under the following conditions:
Total illumination until the thickness reduction reaches 5 nanometers (nm)
Radiation is 1420 Joules / square centimeter (J / c
m²) Or more, preferably 1420 to 28400
Joules / square centimeter (J / cm ²), Especially
Particularly preferably, 1420 to 14200 joules / square
Centimeter (J / cm²). ArF excimer laser light irradiation conditions Pulse energy density: 0.1 (mJ / cm²) / Pulse Repetition frequency: 100 Hz Irradiation area: 10 mm × 10 mm Atmosphere: dry air 20 liter (L) / min (min) Flow (b) Carbon (C) and fluorine (F) or further oxygen (O)
Is a fluororesin whose main component is. (C) Thickness of 0.1 to 10 micrometer (μm)
It is. Using the pellicle film of each aspect obtained by the present invention
If the wavelength is in the range of 140 to 200 nanometers (nm)
Lithography using an exposure light source for ultraviolet light in
An exposure method is provided for use.

[Pellicle Film and Method for Producing the Same] The organic polymer for a pellicle used in the present invention is not necessarily limited to this case, but is preferably a fluororesin containing carbon (C) and fluorine (F) as main components, particularly a fluororesin. Is preferably a fluororesin containing only carbon (C), fluorine (F) and oxygen (O) as components. Among the above fluororesins, a perfluoroamorphous fluororesin having a ring structure in the main chain, particularly a cyclic ether structure, is preferable. As a suitable example of the perfluoroamorphous fluororesin, the following formula is contained in the main chain. (2)

[0030]

Embedded image R: a perfluoroalkylene group p; a number of zero or 1 q; a repeating unit of zero or 1 number, the following formula (3)

[0031]

Embedded image R: a repeating unit of a perfluoroalkylene group, or the following formula (4)

[0032]

Embedded image R: a repeating unit of a perfluoroalkylene group, or the following formula (5)

[0033]

Embedded image R: a perfluoroalkylene group p; a number of zero or 1 q: a repeating unit of the number of zero or 1 The following formula (6)

[0034]

Embedded image And R is a perfluoroalkylene group.

In the perfluorofluororesin, even if all of the repeating units are composed of the above cyclic repeating unit, or a part of the repeating unit is composed of the above cyclic repeating unit and the other part of the repeating unit is linear. It may consist of perfluoromonomer units.

The above-mentioned perfluoroamorphous fluororesin can be obtained by a method known per se, for example, cyclization polymerization of a perfluoroether monomer having a double bond at both terminals, and cyclization polymerization of a cyclic perfluoromonomer. It can be obtained by radical polymerization. A copolymer can be obtained by allowing other perfluoro monomers to coexist during the polymerization.

The perfluoroether monomer having a double bond at both ends is represented by the following formula (7)

Embedded image _{CF 2 = CF- (CF 2)} n-O- (CF 2) m-CF = CF 2 (7) (n = 1~5, m = 1~5, n + m = 1~6) at The perfluoroether represented can be mentioned, and examples thereof include perfluoroallyl vinyl ether, perfluorodiallyl ether, perfluorobutenyl vinyl ether, perfluorobutenyl allyl vinyl ether, and perfluorodibutenyl ether.

Another type of perfluoroether monomer having a double bond at both ends is represented by the following formula (8)

Embedded image embedded image CF ₂ ＣＦCF—O—R—O—CF ＝ CF ₂ (8) R; Perfluoroalkylene glycol divinyl ether represented by perfluoroalkylene group; Examples include ethylene glycol divinyl ether and perfluorotetramethylene glycol divinyl ether.

On the other hand, as the cyclic perfluoro monomer,
For example, the following equation (9)

[0040]

Embedded image R: a monomer represented by a perfluoroalkylene group, particularly perfluoro-2,2-dimethyl-1,3-dioxole.

Examples of other monomers used for copolymerization include tetrafluoroethylene, hexafluoropropylene, perfluorovinyl propyl ether, perfluoroallyl butyl ether, perfluorodivinyl ethyl ether, and perfluorovinyl allyl ether. You.

Specific examples of the amorphous fluororesin include, but are not limited to, a cyclized copolymer of tetrafluoroethylene and perfluorovinyl allyl ether, and Cytop represented by the above formula (1). (Trade name, manufactured by Asahi Glass Co., Ltd.), tetrafluoroethylene and perfluoro-
A copolymer with 2,2-dimethyl-1,3-dioxole, represented by the following formula (10):

[0043]

Embedded image Teflon AF (trade name, manufactured by DuPont, USA, manufactured by Mitsui Dupont Fluorochemicals Co., Ltd.).

In producing the pellicle film, the above organic polymer is dissolved in an appropriate solvent to form a solution. As the solvent, in the case of the above-mentioned fluorine-based resin, a fluorine-based organic solvent,
Particularly, a perfluoro organic solvent is suitable, and examples thereof include perfluoro (2-butyltetrahydrofuran), perfluoro (2-propyltetrahydropyran), perfluorohydrofuran, perfluorooctane, and the like.

The concentration of the organic polymer in the solution is generally 1
It is preferably from 20 to 20% by weight, especially from 2 to 10% by weight, from the viewpoint of the removability of trace metal components and trace colloid components and the film forming property. When the concentration is lower than the above range, the efficiency of film formation and impurity removal deteriorates. On the other hand, when the concentration is higher than the above range, the viscosity of the solution becomes too high, and the workability of film formation and impurity removal tends to decrease.

In the present invention, this organic polymer solution is filtered by a filter having an adsorption action by zeta potential, or by treating with a soluble solvent.
Remove trace metal components and trace colloid components in organic polymer solution.

The filter may be a known porous material for solid-liquid separation, such as a woven or non-woven fabric of fibers, a porous membrane or plate, a packed layer of powder particles, a porous molded body, or a porous material thereof. A combination of two or more, and the like,
It is sufficient that at least a part of these filter media have an adsorption effect by zeta potential.

As a fiber forming the filter, a woven fabric or a nonwoven fabric made of one or more of natural fibers, regenerated fibers, synthetic fibers, and inorganic fibers is used. Examples of the natural fiber include pulp fiber, cotton, cellulose fiber such as ramie, and animal fiber such as wool.
Regenerated cellulose fibers, acetate fibers, and the like obtained by the viscose method or the copper method may be used. Examples of synthetic fibers include olefin fibers made of polyethylene, polypropylene, etc., polyvinyl alcohol fibers, polyvinyl chloride fibers, vinylidene chloride resin fibers, acrylic fibers, vinyl chloride / vinylidene chloride copolymer fibers, nylon 6, nylon 6-6, and the like. Examples thereof include thermoplastic polyester fibers such as polyamide fibers and polyethylene terephthalate, fluororesin fibers such as polytetrafluoroethylene, aramid fibers, and liquid crystal polyester fibers. Glass fibers,
Ceramic fibers, carbon fibers, natural or synthetic mineral fibers and the like can be mentioned. Suitable examples of mineral fibers include, but are not limited to, calcium silicate fibers, magnesium silicate fibers, and basic magnesium silicate fibers such as sepiolite and asbestos. The fibers constituting the filter may be used alone or in combination of two or more kinds, and the form of the fibers may be staple fibers or filament fibers. The thickness of the single fiber is not particularly limited, but is generally 100 denier or less, particularly preferably 50 denier or less.

On the other hand, as the porous membrane, a porous membrane produced by a known means such as a microphase separation method, a stretching method, a charged track etching method and the like is used. In the microphase separation method, a uniform solution in which a polymer such as cellulose acetate, cellulose nitrate, polyvinyl chloride, polyacrylonitrile, polysulfone, polyethersulfone, polyethylene, polypropylene, polyvinylidene fluoride, and polyphenylene oxide is dissolved in a solvent is used. A porous film is formed by thin casting and then immersing in a non-solvent that does not dissolve the polymer, or evaporating the solvent from the cast polymer solution. In the stretching method, for example, a film of polytetrafluoroethylene, polypropylene, or the like is stretched at a high temperature and heat-treated to form a porous film. Further, in the charged track etching method, a polymer film is irradiated with thermal neutrons or the like, and a damaged portion is selectively chemically etched to obtain a porous film. The porous film includes an inorganic film, and an alumina film and a zirconia film are also known.

Further, diatomaceous earth, perlite, activated carbon, talc and the like are used as the packed layer, and these have an adsorbing property, and have an advantage that they are porous and do not cause clogging during filtration.

Further, examples of the porous molded body include a ceramic sintered body such as an unglazed plate or alundum, and a laminate obtained by laminating a plurality of the above-mentioned fiber filter material, a porous membrane, a filling layer, and the like, and integrally molding under heating. Is also used.

The zeta potential of the filter in the filter is generally determined by the material of the filter. Speaking of inorganic filter media, siliceous filter media tend to have a negative zeta potential, whereas alumina and metal silicate media (including basic metal silicates) have a positive zeta potential. Tends to have a potential.

The control of the zeta potential in the filter medium made of an organic polymer can be performed by forming at least a part of the organic polymer with a copolymer resin having an anionic or cationic polar group, or by adding the organic polymer to the organic polymer. This can be achieved by blending a copolymer resin having a polar group. Examples of the anionic polar group include arbitrary polar groups such as carboxylic acid, sulfonic acid, and phosphonic acid. On the other hand, examples of the cationic polar group include primary, secondary, and tertiary amino groups and quaternary groups. Those having an arbitrary cationic group such as an organic ammonium group, an amide group, an imino group, an imide group, a hydrazino group, a basic nitrogen-containing group such as a guanidino group, an amidino group and the like can be mentioned.
A copolymer resin having an anionic or cationic polar group is a resin obtained by incorporating a monomer having an anionic or cationic polar group into the resin by random copolymerization, block copolymerization, or graft copolymerization. It is.

Suitable examples of monomers are as follows. As the carboxylic acid type, ethylenically unsaturated carboxylic acids, for example, acrylic acid, methacrylic acid, crotonic acid,
Maleic acid, maleic anhydride, fumaric acid, lower alkyl half esters such as maleic acid and fumaric acid, and the like. Examples of the sulfonic acid type include styrene sulfonic acid and 2-acrylamido-2-methylpropane sulfonic acid. Examples of the phosphonic acid type include 2-acid phosphoxypropyl methacrylate,
2-acid phosphoxyethyl methacrylate, 3-chloro-2-acid phosphoxypropyl methacrylate, and the like. Basic nitrogen-containing (meth) acrylic monomer: for example, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, dimethylaminopropyl methacrylate, dimethylaminopropyl acrylate, dibutylaminoethyl methacrylate, dimethylaminopropyl Methacrylamide, N, N-dimethylaminoethyl-N′-aminoethyl methacrylate, 3-acrylamide-3,3-
Dimethylpropyldimethylamine, and their quaternary
Grade ammonium salt. Cationic polar group-containing vinyl monomer: for example, diallyldimethylammonium chloride,
Vinyltrimethylammonium chloride, N-vinylcarbazole, 2-vinylimidazole, N-vinylpyrrole, N-vinylindole, N-vinylpyrrolidone,
Quaternary vinyl pyridium.

Depending on the type of impurities to be removed, the filter used in the present invention may have a negative zeta potential adsorption effect or a positive zeta potential adsorption effect. Alternatively, it may have an adsorption effect by negative and positive zeta potentials.

A filter having an adsorption effect by a zeta potential is commercially available from Cuno Inc. under the trade name of Zetaplus or Zetapore (both are registered trademarks) and can be easily obtained and used.

The removal of impurities by filtration of the resin solution for forming a pellicle film is preferably performed until the content of the impurities reaches a predetermined level by repeatedly circulating the solution through the filter. Generally, the filtration pressure is 0.1 to 2.
A pressure of 45 kg / cm ² (gauge) is appropriate, and the temperature and the like are not particularly limited. In general, normal temperature is sufficient, but heating or cooling may be performed as necessary.

Further, prior to or after filtration with a filter having an adsorbing action by a zeta potential, pre-filtration or post-filtration by another filter may be performed in combination. Multi-stage filtration with a filter may be performed.

On the other hand, particularly in the case of a fluororesin containing carbon (C) and fluorine (F) as main components, the above-mentioned trace metal component and / or high molecular weight component and / or incomplete molecular structure component are used. By treating the fluororesin with a soluble solvent, including the operation of removing at least a part, preferably the main part, a pellicle film of a fluororesin having excellent light resistance, which has not been seen before, is obtained. As the fluororesin treated with the soluble solvent, a part of the fluororesin dissolved from the solution of the soluble solvent of the fluororesin can be used as a solution and / or precipitated, and the separated fluororesin can be used. . In addition, in order to remove the high molecular weight component, in addition to the above-mentioned method using a filter having an adsorption effect by the zeta potential, dissolution is performed by adding a poor solvent to the fluororesin solution or changing the temperature of the solution. It is usual to separate and separate the fluororesin that is present.

In order to form a pellicle film using an organic polymer such as a fluororesin obtained by the above-described removal of impurities or treatment with a soluble solvent, a casting film forming method known per se, for example, a spin coating method, It can be performed by a knife coating method or the like, and it is generally preferable to form a thin film by casting a resin solution on a smooth substrate surface such as a glass plate. The thickness of the formed thin film can be easily changed by changing the solution viscosity, the rotation speed of the substrate, and the like.

The thin film formed on the substrate can be dried by means such as hot air or infrared irradiation to remove the residual solvent.

The thickness of the pellicle film is generally 0.1 to 1
In the range of 0 micrometer (μm), it is preferable to set the transmittance to the wavelength of the vacuum ultraviolet light to be used to be high.
A thickness of 5 to 1 μm is appropriate.

The pellicle film of the present invention may be used as it is, or may be used by forming a known inorganic or organic antireflection film on one or both surfaces of the film. it can.

[Pellicle and Lithography] The pellicle used in the exposure method of the present invention is obtained by stretching a pellicle film obtained by the above method on one side of a pellicle frame and applying an adhesive to the other side, or a double-sided tape. Can be attached on the mask by sticking or the like. The pellicle frame is not limited to this, but is made of metal such as aluminum, aluminum alloy, stainless steel,
Those made of synthetic resin or ceramic are used.
In order to stretch the pellicle film on the pellicle frame, an adhesive known per se, for example, a silicone resin adhesive or a fluororesin adhesive is used. According to the structure of the pellicle, foreign matter can be prevented from entering the inside from the outside, and even if foreign matter adheres to the film, it is transferred in a blurred state at the time of exposure, which causes a problem. Hateful.

In order to prevent the generation of dust inside the pellicle, an adhesive substance layer known per se can be formed on the inner surface of the pellicle frame or the inner surface of the pellicle film.
That is, if an adhesive layer is provided inside the pellicle frame or film,
It prevents dust from the inside of the pellicle and also fixes floating dust to prevent it from adhering to the mask.
It is excellent in that.

In the exposure method of the present invention, the pellicle provided with the pellicle film manufactured by the above-described method is mounted on a photomask or reticle in which a circuit pattern is formed on the surface of a glass plate with a deposited film of chromium or the like, and the resist is removed. The circuit pattern is transferred onto the coated silicon wafer by exposure using an ultraviolet exposure light source having a wavelength in the range of 140 to 200 nm. According to the present invention, even when ultraviolet light, particularly vacuum ultraviolet light, is used, a decrease in light resistance due to photodecomposition of the pellicle is small, and as a result, a sharp and fine pattern is stable for a relatively long time by lithography. Can be formed.

[0067]

The pellicle film of the present invention has reduced impurities in the film, has excellent transparency to ultraviolet light, in particular, vacuum ultraviolet light, suppresses the tendency of the film thickness to decrease by photolysis, and has excellent properties. It has the characteristic of having light resistance. Further, according to the method of the present invention, the resin solution for film formation is passed through a filter having an adsorbing action by zeta potential, or by a simple operation of being precipitated by a soluble solvent, the permeability of ultraviolet light is reduced. It is excellent in that the causal impurities can be removed and the operation is simple. Furthermore,
According to the present invention, ultraviolet light, especially when using vacuum ultraviolet light, less decrease in light resistance due to photodecomposition of the pellicle,
As a result, there is an advantage that a sharp and fine pattern can be formed by lithography for a relatively long time.

[0068]

The present invention is further described by the following examples.

<Example 1> Fluoropolymer resin CYTO
P (manufactured by Asahi Glass Co., Ltd., grade having high ultraviolet transmittance) was dissolved in a fluorine solvent EFTOP EF-L174 (manufactured by Tochem Products) to prepare a 4% by weight fluoropolymer solution. Next, the solution was circulated and filtered under the following conditions. Filter material: Zeta Plus Filter (Cuno, EC
050) Flow rate: 4 ml / min Filtration time: 10 days The filtered fluoropolymer solution was dried under reduced pressure at 120 ° C. × 12 hours to collect the dried fluoropolymer. About 1 g of this fluoropolymer was burned, and the residue was subjected to metal analysis by the ICP method, whereby the content of metal in the fluoropolymer was measured. Table 1 shows the obtained results. The detection limit was 1 ppm or less for all metal components in the fluoropolymer. The intrinsic viscosity [η] of the fluoropolymer purified by filtration is determined by the intrinsic viscosity method (solvent: F-top EF-L102).
Calculated by Tochem Products Co., Ltd.
6 (dl / g).

<Comparative Example 1> A dried fluoropolymer was recovered in exactly the same manner as in Example 1 except that circulation filtration using a Zetaplus filter was not performed. The metal component was analyzed for this fluoropolymer in the same manner as in Example 1. Table 1 shows the obtained results. Na and Ca which were not detected in Example 1 were detected, and it is confirmed by comparison with Comparative Example 1 that these metal components were removed by zeta plus filter filtration. The intrinsic viscosity of the fluoropolymer of Comparative Example 1 was measured in the same manner as in Example 1. As a result, the intrinsic viscosity was 0.60, which was higher than that of the fluoropolymer subjected to the Zeta Plus filter filtration. As a result, it was confirmed that the high molecular weight component of the fluoropolymer was removed.

Comparative Example 2 A fluoropolymer film (pellicle film) having a thickness of 0.8 μm was formed by spin coating using a fluoropolymer solution prepared in Example 1 which was not filtered through a zeta-plus filter. Was prepared. The obtained film was irradiated with ArF excimer laser light (λ = 193 nm) under the following conditions. Laser light irradiation conditions-Pulse energy density: 0. l (mJ / cm ² ) / pulse Repetition frequency: 100 Hz Irradiation area: 10 mm × 10 mm Atmosphere: dry air 20 L / min. The curve (A) in FIG. 2 shows the relationship between the total irradiation amount of the ArF excimer laser light and the amount of reduction in the thickness of the fluoropolymer film caused by the laser irradiation. In FIG. 1, assuming that the life of the fluoropolymer film as a pellicle film is up to a thickness reduction of 5 nm, it was found that the light resistance life was 960 J / cm ² .

Example 2 A fluoropolymer film (pellicle film) was prepared in exactly the same manner as in Comparative Example 2 except that the fluoropolymer solution prepared in Example 1 was filtered through a zeta-plus filter. Fabrication and irradiation with ArF excimer laser light were performed to measure the thickness reduction amount. The total irradiation dose until the thickness reduction reaches 5 nm is 1420 J
/ Cm ^2, which means that the light resistance life can be improved about 1.5 times as compared with Comparative Example 2.

<Example 3> Except that Perflud IL263 (manufactured by Tokuyama Corporation) was used as the fluorine solvent,
Using the same materials as in Example 1, a 4% by weight fluoropolymer solution was prepared. Next, impurity treatment with a soluble solvent was performed as follows using m-XHF (meta-xylene hexafluoride) as a poor solvent. In a 4% by weight fluoropolymer solution, m-XHF is
The solution was dropped at a rate of 0.80 vol with respect to 1 vol of the fluoropolymer solution, and a supernatant was collected (24.1 wt% was removed by precipitation with respect to 100 wt% of the fluoropolymer in the initial solution). The supernatant obtained in m-XHF was washed with m-XHF.
Dropping was performed at a rate of 0.73 vol with respect to 1 vol, and a precipitate was collected (100% by weight of the polymer in the initial solution).
(A polymer in the supernatant portion was 3.8% by weight). Was subjected to the same drying treatment as in Example 1, and the dried fluoropolymer was recovered. The metal component of this fluoropolymer was analyzed in the same manner as in Example 1.
Table 1 shows the obtained results. N detected in Comparative Example 1
The values of a and Ca were below the detection limit, and it was confirmed that these metal components were removed by the treatment with the soluble solvent. The intrinsic viscosity of the fluoropolymer of Example 3 was measured in the same manner as in Example 1.
It was confirmed that the molecular weight of the fluoropolymer was lower than that of the fluoropolymer of Comparative Example 1, and the high molecular weight component of the fluoropolymer was removed by the treatment with the soluble solvent.

Example 4 The precipitate-precipitated part obtained in Example 3 was dissolved in a fluorine solvent Perflud IL-263 to prepare a 4% by weight fluoropolymer solution. Except for using this solution, a fluoropolymer film (pellicle film) was formed and irradiation with ArF excimer laser light was performed in the same manner as in Comparative Example 2 to measure the amount of decrease in film thickness.
The results are shown in FIG. The irradiation amount until the film thickness reduction amount reaches 5 nm is 2080 J / cm ² , and it can be seen that the light fastness life can be improved more than twice as compared with Comparative Example 2.

[0075]

[Table 1]

[Brief description of the drawings]

FIG. 1 is an ultraviolet spectral absorption curve showing a result of calculating an absorption wavelength corresponding to the molecular structure of a fluororesin having a chemical structure represented by the formula (1) using a molecular orbital method.

Fig. 2 Fluorine resin without impurity removal treatment (O)
Fluorine resin (●) subjected to impurity removal treatment by a filter having an adsorption action by zeta potential, and fluorine resin (▲) subjected to impurity removal treatment by soluble solvent treatment were irradiated with ArF excimer laser having a wavelength of 193 nm. 4 is a graph plotting the relationship between the total irradiation dose (J / cm ² ) and the thickness reduction (nm).

FIG. 3 is a diagram for explaining the relationship between potential energy (vertical axis) for colloid particles and distance between colloid particles (horizontal axis).

Claims (14)

[Claims] 1. A pellicle film characterized by simultaneously satisfying the following conditions (a) to (c). (A) When irradiated with ArF excimer laser light (wavelength λ = 193 nanometers (nm)) under the following conditions, the total irradiation amount until the thickness reduction amount reaches 5 nanometers (nm) is 1420 Joules / Square centimeter (J / c
m ² ) or more. ArF excimer laser light irradiation conditions • Pulse energy density: 0.1 (mJ / cm ² ) / pulse • Repetition frequency: 100 Hz • Irradiation area: 10 mm x 10 mm • Atmosphere: 20 liters of dry air (L) / min (min) Flow (b) Carbon (C) and fluorine (F) or even oxygen (O)
Is a fluororesin whose main component is (C) Thickness of 0.1 to 10 micrometer (μm)
It is. 2. The method according to claim 1, wherein the organic polymer is subjected to an operation of removing a trace metal component and / or a high molecular weight component contained in the organic polymer to obtain an impurity-removed organic polymer as a material for the pellicle film. Pellicle membrane. 3. An organic polymer obtained by treating an organic polymer to remove at least a part of at least any of trace metal components, high molecular weight components and incomplete molecular structural components contained in the organic polymer. A pellicle film using an impurity-removing organic polymer as a material for the pellicle film. 4. An operation for obtaining an impurity-removed organic polymer from which a trace metal component and / or a high molecular weight component contained in the organic polymer has been removed, using a filter having an adsorption effect by a zeta potential. Item 2
A method for producing the pellicle membrane described in the above. 5. A trace metal component contained in an organic polymer,
An operation for obtaining an impurity-removed organic polymer from which at least one of the high molecular weight component and the incomplete molecular structure component has been removed is performed using a filter having an adsorption effect by a zeta potential. A method for producing a pellicle film according to claim 3. 6. A pellicle film obtained by the method for producing a pellicle film according to claim 4. 7. The pellicle film according to claim 1, wherein the content of each trace metal component in the impurity-removed organic polymer is 1 ppm or less. 8. The pellicle film according to claim 2, wherein the organic polymer is a fluororesin containing carbon (C) and fluorine (F) as main components. 9. The pellicle film according to claim 2, wherein the organic polymer is a fluororesin containing only carbon (C), fluorine (F) and oxygen (O) as constituent components. 10. A pellicle film comprising a fluororesin containing carbon (C) and fluorine (F) as main constituents, the fluororesin being treated with a soluble solvent thereof. 11. A fluororesin treated with a soluble solvent, and a part of the fluororesin dissolved from a solution of the fluororesin soluble solvent is separated from the fluororesin as a solution and / or by precipitation. A pellicle film characterized by using: 12. The method according to claim 1, wherein the content of each metal component in the fluororesin is 1 ppm or less.
12. The pellicle film according to 0 or 11. 13. Use of a fluororesin from which at least one of trace metal components, high molecular weight components and incomplete molecular structure components in the fluororesin has been removed by treating with a soluble solvent. A pellicle film characterized by the following. 14. Use of the pellicle film according to any one of claims 1 to 3 and 7 to 13 for lithography using an exposure light source for ultraviolet light having a wavelength in the range of 140 to 200 nanometers (nm). An exposure method, comprising: