Pellicle film and pellicle

Abstract

Provided is a pellicle film that, by using polysilsesquioxane having a random structure as a film material, exhibits excellent transmittance for light having a wavelength suitable for photolithography, and that can ensure mechanical strength and / or light resistance.

Description

Pellicle membrane, and pellicle

[0001] This invention relates to a pellicle film and a pellicle.

[0002] In pattern formation processes for electronic devices and the like, a dustproofing device called a pellicle is commonly used. A pellicle has a structure in which a transparent polymer thin film (hereinafter referred to as "pellicle film") is stretched and attached to a frame, and it has the function of preventing foreign matter from adhering to the photomask, reticle, etc.

[0003] Regarding the material for the pellicle film, Patent Document 1 describes a pellicle material made of polyladdersiloxane having repeating units in its molecule that can be represented by a specific general formula. Patent Document 1 reports that by constructing a pellicle film using such a pellicle material, the degradation of the pellicle material can be suppressed when exposed to laser light using short-wavelength light.

[0004] Japanese Unexamined Patent Publication No. 4-166840

[0005] However, given the recent trend towards miniaturization of patterns in electronic devices and the like, conventional pellicle films using pellicle materials, such as those described in Patent Document 1, had room for improvement in terms of transmittance to light with wavelengths suitable for photolithography.

[0006] Furthermore, as pellicle films continue to become thinner, there has been a need to solve the problem of how to ensure mechanical strength and / or light resistance (durability against light) in pellicle films.

[0007] The object of the present invention is to provide a novel pellicle film that exhibits excellent transmittance to light having wavelengths suitable for photolithography, and that can ensure mechanical strength and / or light resistance. Another object of the present invention is to provide a pellicle using such a pellicle film.

[0008] One aspect of the present invention is as follows: [1] A pellicle film comprising a polysilsesquioxane having a random structure. [2] The polysilsesquioxane is of the following formula (T): {In the formula, R ３ [3] The pellicle film according to item 1, comprising a structural unit represented by}. [4] The pellicle film according to item 2, wherein the content of the structural unit represented by formula (T) in the polysilsesquioxane is 20 mol% or more and 85 mol% or less. [5] The polysilsesquioxane is represented by the following formula (D): {In the formula, R ２ Each independently represents a hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom (-H) which may have substituents comprising at least one functional group selected from the group consisting of a halogen group, an oxa group (-O-), a carbonyl group (>C=O), and an epoxy group. A pellicle film according to any one of items 1 to 3, comprising a structural unit represented by}. [5] A pellicle film according to item 4, wherein the content of the structural unit represented by formula (D) in the polysilsesquioxane is 1 mol% or more and 60 mol% or less. [6] The polysilsesquioxane is the following formula (Q): A pellicle membrane according to any one of items 1 to 5, comprising a constituent unit represented by the formula (Q). [7] A pellicle membrane according to item 6, wherein the content of the constituent unit represented by the formula (Q) in the polysilsesquioxane is 0 mol% or more and 25 mol% or less. [8] The polysilsesquioxane is the following formula (M): {In the formula, R 1Each independently represents a hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom (-H) which may have substituents comprising at least one functional group selected from the group consisting of a halogen group, an oxa group (-O-), a carbonyl group (>C=O), and an epoxy group. A pellicle film according to any one of items 1 to 6, comprising a structural unit represented by}. [9] A pellicle film according to item 8, wherein the content of the structural unit represented by formula (M) in the polysilsesquioxane is 0 mol% or more and 10 mol% or less.

[10] The structural unit represented by formula (T) is the following formula (T1): (In the formula, R ３１

[11] A pellicle film according to item 2, comprising a structural unit represented by ) (where represents a hydrocarbon group having 1 to 10 carbon atoms and containing a halogen group).

[12] A pellicle film according to any one of items 1 to 10, having a transmittance of 80% or more to light with a wavelength of 193 nm.

[13] A pellicle film according to any one of items 1 to 10, having a transmittance of 80% or more to light with a wavelength of 248 nm.

[14] A pellicle having a pellicle film according to any one of items 1 to 13.

[15] A resin composition for a pellicle film comprising a polysilsesquioxane having a random structure.

[16] A method for protecting a photomask, characterized by attaching a pellicle film according to any one of claims 1 to 13 to the surface of a photomask and performing exposure using short-wavelength light.

[0009] According to the present invention, it is possible to provide a novel pellicle film that exhibits excellent transmittance to light having wavelengths suitable for photolithography, and that can ensure mechanical strength and / or light resistance. Furthermore, according to the present invention, it is possible to provide a pellicle using such a pellicle film.

[0010] This figure shows an example of the pellicle configuration according to this embodiment.

[0011] The embodiments provided by this disclosure will be described below. However, the embodiments provided by this disclosure are not limited to those described below, and are therefore capable of being modified in various ways within the scope of the gist of the present invention.

[0012] In this disclosure, all measurements are performed according to the methods described in the examples, unless otherwise specified. In the numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced by the upper or lower limit of another numerical range described in stages, or by the values ​​shown in the examples. In this disclosure, the term "process" is included not only in the sense of an independent process, but also in the sense of achieving the function of a process, even if it cannot be clearly distinguished from other processes. In the contents shown in the drawings, the scale, shape, and length may be exaggerated for further clarity.

[0013] In this disclosure, if there are multiple structures represented by the same reference numeral in the same formula, unless otherwise specified, each structure may be selected independently and may be identical or different from one another. Similarly, if there are multiple structures represented by the same reference numeral in different formulas, unless otherwise specified, each structure may be selected independently and may be identical or different from one another.

[0014] [First Embodiment] <Pellicle Film> The pellicle film of the present disclosure (hereinafter sometimes referred to as "the pellicle film") comprises a polysilsesquioxane having a random structure (hereinafter sometimes referred to as "the polysilsesquioxane").

[0015] The inventors of this invention have diligently conducted research to find a pellicle film usable for photolithography using ArF, KrF, j-line, i-line, h-line, g-line, etc. As a result, they have found that by using this polysilsesquioxane as a material, it is possible to realize a pellicle film that exhibits excellent transmittance to light with wavelengths suitable for photolithography. Because this pellicle film exhibits excellent transmittance to light with wavelengths suitable for photolithography, particularly light with wavelengths of 193 nm to 248 nm, it can meet the demands of next-generation electronic devices, such as the demand for further miniaturization of patterns.

[0016] Furthermore, this pellicle film exhibits not only excellent transmittance but also superior mechanical strength, such as puncture resistance, and / or light resistance (durability against light, particularly against light with wavelengths of 193 nm to 248 nm). Therefore, this disclosure can provide a highly practical pellicle film in terms of transmittance, mechanical strength, and / or light resistance.

[0017] <<Polysilsesquioxane with Random Structure>> This polysilsesquioxane has a random structure, in which the constituent units derived from the monomers that make it up are arranged randomly. Here, "polysilsesquioxane" refers to the following T unit, which is a unit formed by the condensation of trifunctional silanes, for example: (In the above units, R is any substituent.) This means a polysiloxane containing the following. However, this polysilsesquioxane only needs to contain at least one T unit, and therefore a T unit and a unit other than the T unit, for example, the M unit below: (In the above units, R is any substituent.) The following D units: (In the above units, R is any substituent), and the following Q units: It may be a polysiloxane comprising at least one unit selected from the group consisting of the following:

[0018] Silsesquioxanes have been reported to include (oligo)silsesquioxanes that possess cage structures, ladder structures, etc. For example, silsesquioxanes with cage structures have a regularly arranged siloxane skeleton (••Si–O–Si••) and a polyhedral structure formed by the siloxane skeleton.

[0019] This polysilsesquioxane does not exclude polysilsesquioxanes that partially have regularly arranged siloxane skeletons such as cage structures and ladder structures. Polysilsesquioxanes that are classified as having a random structure, even if they have partial regularity, fall under this category of polysilsesquioxane. The proportion of regularly arranged siloxane skeleton units that this polysilsesquioxane may partially possess (in one embodiment, the proportion of siloxane skeletons having a cage structure or ladder structure) is 5% by mass or less of the total polysilsesquioxane. The following formula conceptually represents the siloxane skeleton of this polysilsesquioxane having a random structure. The following formula represents a structure in which siloxane skeletons formed only of T units are irregularly linked. (In the formula, R is an arbitrary substituent, independently of any other substituent.)

[0020] The “random structure” in this disclosure can be obtained, for example, by pre-mixing multiple types of raw materials and then subjecting them to polymerization, as described in the examples.

[0021] This polysilsesquioxane is given by the following formula (T): {In the formula, R ３ It is preferable to include a structural unit represented by}. Including a structural unit represented by the following formula (T) makes it easier to further ensure mechanical strength, etc., in the pellicle film.

[0022] Multiple Rs are included in the repeating unit.３ each independently represents a "hydrocarbon group having 1 to 20 carbon atoms which may have a substituent containing at least one functional group selected from the group consisting of a halogeno group, an oxa group (—O—), a carbonyl group (>C═O), and an epoxy group", or a "hydrogen atom (—H)". Among these, the "hydrocarbon group" may be a hydrocarbon group having any of a linear structure, a branched structure, and / or a cyclic structure, and may also be a hydrocarbon group having a carbon-carbon unsaturated bond (for example, a carbon-carbon double bond structure and a carbon-carbon triple bond structure), or a hydrocarbon group having no carbon-carbon unsaturated bond. When the "hydrocarbon group" has a cyclic structure, such a ring may be an alicyclic ring or an aromatic ring. Therefore, an aliphatic hydrocarbon group and an aromatic hydrocarbon group having one cyclic structure (i.e., monocyclic) and those having a number of cyclic structures (i.e., polycyclic) are also included in the concept of the "hydrocarbon group". Naturally, those referred to as an alkyl group, an alkenyl group, an alkynyl group, an aryl group, etc. are included in the concept of the "hydrocarbon group". Further, the phrase "which may have a substituent containing at least one functional group selected from the group consisting of a halogeno group, an oxa group (—O—), a carbonyl group (>C═O), and an epoxy group" means, for example, that a hydrogen atom of the hydrocarbon group may be substituted with a fluoro group (—F), a chloro group (—Cl), a bromo group (—Br), etc., or two hydrogen atoms of the hydrocarbon group may be substituted with an epoxy group, and further, a carbon atom of the hydrocarbon group may be substituted with an oxa group (—O—), a carbonyl group (>C═O), etc.

[0023] R ３ When R is a hydrocarbon group, the number of carbon atoms is preferably 10 or less, more preferably 8 or less, still more preferably 6 or less, and particularly preferably 4 or less.

[0024] R ３ Examples of the hydrocarbon group of R include a 4,4,4-trifluorobutyl group (—CH ２ CH ２ CH ２ CF ３ ), a 2,2,2-trifluoroethyl group (—CH ２ CF ３), 3,3,3-trifluoropropyl group (-CH ２ CH ２ CF ３ ), 2-chloroethyl group (-CH ２ CH ２ Cl), and 2-chlorophenyl group (-C ６ H ４ Groups such as Cl (hydrocarbon groups with 1 to 10 carbon atoms, including halogen groups as substituents); methyl group (-CH ３ , Me), ethyl group (-CH ２ CH ３ , Et), vinyl group (-CH=CH ２ ), n-propyl group (-CH ２ CH ２ CH ３ , ｎ Pr), i-propyl group (-CH(CH ３ ) ２ , ｉ Pr), n-butyl group (-CH ２ CH ２ CH ２ CH ３ , ｎ Butu), t-butyl group (-C(CH ３ ) ３ , ｔ Bu), cyclohexyl group (-C ６ H １１ ), and phenyl group (-C ６ H ５ Groups such as , Ph) {Hydroxide groups with 1 to 10 carbon atoms, not containing halogen groups, oxa groups (-O-), carbonyl groups (>C=O), or epoxy groups as substituents}; 2-ethoxyethyl group (-CH ２ CH ２ OCH ２ CH ３ Examples include groups such as {carbon hydrocarbon groups having 1 to 10 carbon atoms and containing an oxa group (-O-) as a substituent}; among these, hydrocarbon groups having 1 to 10 carbon atoms and containing a halogeno group as a substituent are preferred, and 4,4,4-trifluorobutyl group (-CH ２ CH ２ CH ２ CF ３ ), 2,2,2-trifluoroethyl group (-CH ２ CF３ ), 3,3,3-trifluoropropyl group (-CH ２ CH ２ CF ３ ), 2-chloroethyl group (-CH ２ CH ２ Cl), 2-chlorophenyl group (-C ６ H ４ Cl) is even more preferred. In this disclosure, "halogeno group" means a fluoro group (-F), a chloro group (-Cl), a bromo group (-Br), and an iodine group (-I).

[0025] The constituent unit represented by formula (T) is shown in formula (T1): (In the formula, R ３１ (where represents a hydrocarbon group having 1 to 10 carbon atoms that includes a halogen group.) Examples of constituent units are those represented by formula (T1). By including the constituent unit represented by formula (T1), it is easier to ensure flexibility and other properties in the pellicle film.

[0026] Furthermore, examples of constituent units represented by formula (T) include the constituent unit represented by formula (T1-1), the constituent unit represented by formula (T1-2), the constituent unit represented by formula (T1-3), the constituent unit represented by formula (T1-4), the constituent unit represented by formula (T1-5), the constituent unit represented by formula (T2-1), the constituent unit represented by formula (T2-2), the constituent unit represented by formula (T2-3), the constituent unit represented by formula (T2-4), the constituent unit represented by formula (T3-1), and so on. Note that this polysilsesquioxane may contain two or more constituent units represented by formula (T) that are different from each other.

[0027] In this polysilsesquioxane, the content of the constituent unit represented by formula (T) can usually be between 20 mol% and 85 mol%, when the total mass of the monomers that make up the constituent unit is 100 mol%. Preferably, the lower limit that can be combined with the above range is 30 mol% or more, more preferably 40 mol% or more, and even more preferably 45 mol% or more. Preferably, the upper limit that can be combined with the above range is 80 mol% or less. When the content of the constituent unit represented by formula (T) is within the above range, it is easier to further ensure film-forming properties, mechanical strength, etc., in the pellicle film.

[0028] This polysilsesquioxane is represented by the following formula (D): {In the formula, R ２ Each of these independently represents a hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom (-H) which may have substituents comprising at least one functional group selected from the group consisting of a halogen group, an oxa group (-O-), a carbonyl group (>C=O), and an epoxy group. It is preferable to include a structural unit represented by}. Including a structural unit represented by the following formula (D) makes it easier to further ensure flexibility and other properties in the pellicle film.

[0029] R ２ These independently represent "a hydrocarbon group having 1 to 20 carbon atoms, which may have substituents including at least one functional group selected from the group consisting of a halogen group, an oxa group (-O-), a carbonyl group (>C=O), and an epoxy group," and "a hydrogen atom (-H)," but "hydrocarbon group" is R ３ This is equivalent to the case described above.

[0030] R ２ When the group is a hydrocarbon group, the number of carbon atoms is preferably 10 or less, more preferably 8 or less, even more preferably 6 or less, and particularly preferably 4 or less.

[0031] R ２ The hydrocarbon group is a methyl group (-CH ３ , Me), ethyl group (-CH ２ CH ３ , Et), vinyl group (-CH=CH ２ ), n-propyl group (-CH２ CH ２ CH ３ 、 ｎ Pr), i-propyl group (-CH(CH ３ ) ２ 、 ｉ Pr), n-butyl group (-CH ２ CH ２ CH ２ CH ３ 、 ｎ Bu), t-butyl group (-C(CH ３ ) ３ 、 ｔ Bu), cyclohexyl group (-C ６ H １１ ), and phenyl group (-C ６ H ５ , Ph), etc. {As substituents, hydrocarbon groups having 1 to 10 carbon atoms that do not include a halogeno group, an oxa group (-O-), a carbonyl group (>C=O), and an epoxy group} can be mentioned.

[0032] As the structural unit represented by formula (D), the structural unit represented by the following formula (D2-1), the structural unit represented by the following formula (D2-2), the structural unit represented by the following formula (D2-3), the structural unit represented by the following formula (D2-4), etc. can be mentioned. Note that this polysilsesquioxane may contain two or more different structural units represented by formula (D).

[0033] In this polysilsesquioxane, when the total charged mass of the monomers that become the structural units is 100 mol%, the content of the structural unit represented by formula (D) can usually be 1 mol% or more and 60 mol% or less. As the lower limit value that can be combined with the above range, it is preferably 5 mol% or more, more preferably 10 mol% or more, and still more preferably 15 mol% or more. Also, as the upper limit value that can be combined with the above range, it is preferably 55 mol% or less, more preferably 50 mol% or less. When the content of the structural unit represented by formula (D) is within the above range, it is easier to further ensure flexibility, etc. in the pellicle film.

[0034] This polysilsesquioxane may contain a structural unit represented by the following formula (Q): represented by

[0035] In this polysilsesquioxane, the content of the constituent unit represented by formula (Q) can usually be 20 mol% or less, preferably 15 mol% or less, and more preferably 10 mol% or less, when the total mass of monomers that make up the constituent unit is 100 mol%. When the content of the constituent unit represented by formula (Q) is within the above range, it is easier to ensure flexibility and other properties in the pellicle film. However, the content of the constituent unit represented by formula (Q) in this polysilsesquioxane may be 0 mol% depending on the raw material formulation.

[0036] This polysilsesquioxane is expressed in the following formula (M): {In the formula, R 1 Each independently represents a hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom (-H) which may have substituents comprising at least one functional group selected from the group consisting of a halogen group, an oxa group (-O-), a carbonyl group (>C=O), and an epoxy group.} is a constituent unit represented by the following formula (M'): {In the formula, R ４ Each of these independently represents a hydrocarbon group having 1 to 3 carbon atoms, which may have substituents containing at least one functional group selected from the group consisting of vinyl groups and epoxy groups. The constituent units represented by} may also be included.

[0037] R in equation (M) １ These are R, defined independently for the above equation (T). ３ It is fine to use the same as above. R in equation (M') ４ This represents a hydrocarbon group having 1 to 3 carbon atoms, which may have substituents including at least one functional group selected from the group consisting of vinyl groups and epoxy groups. Specifically, it may be an alkyl group having 1 to 3 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, etc.

[0038] Specific examples of raw materials include, but are not limited to, chlorotrimethylsilane, hexamethyldisiloxane, chlorodimethylvinylsilane, and 3-glycidyloxypropyl(methoxy)dimethylsilane.

[0039] The content of the constituent unit represented by formula (M) or (M') in this polysilsesquioxane can usually be 10 mol% or less, preferably 8 mol% or less, and more preferably 6 mol% or less, when the total mass of monomers that make up the constituent unit is 100 mol%. When the content of the constituent unit represented by formula (M) or (M') is within the above range, there are advantages such as easier adjustment of the flexibility of the pellicle film and easier maintenance of liquid stability. However, the content of the constituent unit represented by formula (M) or (M') in this polysilsesquioxane may be 0 mol% depending on the raw material formulation.

[0040] The composition of this polysilsesquioxane and the content of each constituent unit represented by the above formulas can be determined, for example, by NMR measurement of the pellicle film or a sample obtained therefrom. The composition of this polysilsesquioxane or the content of each constituent unit is not limited, but can be adjusted to the above numerical range by controlling, for example, the monomer content ratio at the time of raw material charging in the manufacturing process of this polysilsesquioxane or the pellicle film. This disclosure does not wish to be bound by theory, but the composition of this polysilsesquioxane or the content of each constituent unit in the pellicle film is approximately equal to the monomer content ratio at the time of raw material charging.

[0041] The weight-average molecular weight (Mw) of this polysilsesquioxane can typically be between 500 and 500,000. A preferred lower limit that can be combined with the above range is 1,000 or more, more preferably 1,500 or more. A preferred upper limit that can be combined with the above range is 400,000 or less, more preferably 350,000 or less. When the weight-average molecular weight is within the above range, it becomes easier to ensure the light transmittance, mechanical strength, and light resistance of the pellicle film. The weight-average molecular weight can be determined based on a chromatogram measured by gel permeation chromatography (GPC).

[0042] <<Method for Producing Polysilsesquioxane>> The method for producing this polysilsesquioxane is not particularly limited, and known methods can be appropriately employed. For example, a monomer represented by the following formula (TM); a monomer represented by the following formula (DM); a monomer represented by the following formula (QM); and at least one selected from the group consisting of an oligomer obtained by condensing at least one selected from the group consisting of a monomer represented by the following formula (TM), a monomer represented by the following formula (DM), and a monomer represented by the following formula (QM). A method including a condensation step (hereinafter, may be referred to as the "condensation step") of hydrolyzing and dehydrating and condensing at least one raw material selected from the group (hereinafter, may be simply referred to as "raw material") to obtain polysilsesquioxane. The above oligomer as a raw material can be obtained, for example, by the "oligomer preparation step" described later. {In the formula, R ３ represents a hydrocarbon group having 1 to 20 carbon atoms which may have at least one functional group selected from the group consisting of a halogeno group, an oxa group (-O-), a carbonyl group (>C=O), and an epoxy group, and X each independently represents an alkoxy group having 1 to 6 carbon atoms, a chloro group (-Cl), a bromo group (-Br), an iodo group (-I), or a hydrogen atom (-H).} {In the formula, R ２ each independently represents a hydrocarbon group having 1 to 20 carbon atoms which may have at least one functional group selected from the group consisting of a halogeno group, an oxa group (-O-), a carbonyl group (>C=O), and an epoxy group, and X each independently represents an alkoxy group having 1 to 6 carbon atoms, a chloro group (-Cl), a bromo group (-Br), an iodo group (-I), or a hydrogen atom (-H).} {In the formula, X each independently represents an alkoxy group having 1 to 6 carbon atoms, a chloro group (-Cl), a bromo group (-Br), an iodo group (-I), a hydrogen atom (-H), or a hydroxy group (-OH).}

[0043] If desired, a raw material capable of deriving a structural unit represented by the above formula (M) or (M') may also be used in the "oligomer preparation step" or "condensation step" described later.

[0044] Specific examples of raw materials capable of producing this polysilsesquioxane include, but are not limited to, diethoxydimethylsilane, methyltriethoxysilane, (3,3,3-trifluoropropyl)triethoxysilane, tetraethoxysilane, as well as chlorotrimethylsilane, hexamethyldisiloxane, chlorodimethylvinylsilane, and 3-glycidyloxypropyl(methoxy)dimethylsilane.

[0045] The reaction conditions for the condensation step are not particularly limited, and known conditions can be used as appropriate. For example, the raw materials may be added dropwise to a solution containing a solvent including water and alcohol, and a catalyst. The "solvent," "catalyst," etc., will be described in detail below.

[0046] The solvent usable in the condensation process preferably contains water and alcohol. Examples of alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-ethoxyethanol, 4-methyl-2-pentanol, and 2-butoxyethanol.

[0047] Acidic catalysts usable in the condensation process include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and boric acid; and organic acids such as formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, succinic acid, maleic acid, lactic acid, methanesulfonic acid, and p-toluenesulfonic acid. In the condensation process, either an acidic catalyst or a basic catalyst can be used, and these catalysts can also be used in combination. Acidic catalysts include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and boric acid; and organic acids such as formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, succinic acid, maleic acid, lactic acid, methanesulfonic acid, and p-toluenesulfonic acid. Basic catalysts include inorganic bases such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, and ammonia; and organic amine compounds such as tetramethylammonium hydroxide and triethylamine.

[0048] The amount of catalyst blended in the condensation process can usually be 0.1 mol% to 50 mol% per mol of raw material, preferably 0.1 mol% to 20 mol%, and more preferably 0.2 mol% to 8 mol%.

[0049] The concentration of the raw materials (raw material / solution) in the condensation process can usually be between 5 mol% and 80 mol%, and preferably between 10 mol% and 50 mol.

[0050] The reaction temperature in the condensation step can usually be between 20°C and 80°C. The reaction time in the condensation step can usually be between 0.05 hours and 24 hours, preferably between 0.1 hours and 8 hours.

[0051] The present polysilsesquioxane production method may include an oligomer preparation step (hereinafter sometimes referred to as the "oligomer preparation step") in which at least one monomer selected from the group consisting of monomers represented by formula (TM), monomers represented by formula (DM), and monomers represented by formula (QM) is hydrolyzed and dehydrated to obtain an oligomer.

[0052] The reaction conditions in the oligomer preparation step are not particularly limited, and known conditions can be used as appropriate. For example, the starting materials may be added dropwise to a solution containing water, a solvent containing a ketone or ester, and a catalyst. The catalyst in the oligomer preparation step may be the same as that used in the condensation step.

[0053] The solvents that can be used in the oligomer preparation step are preferably solvents containing water and a ketone or ester. Examples of ketones include methyl isobutyl ketone and methyl amyl ketone. Examples of esters include ethyl acetate, n-propyl acetate, n-butyl acetate, and propylene glycol monomethyl ether acetate.

[0054] The monomer concentration (monomer / solution) in the oligomer preparation step can usually be between 5 mol% and 40 mol%, and preferably between 10 mol% and 35 mol.

[0055] The reaction temperature in the oligomer preparation step can usually be between 40°C and 200°C, preferably between 70°C and 160°C. The reaction time in the oligomer preparation step can usually be between 0.1 hours and 72 hours, preferably between 0.5 hours and 24 hours.

[0056] The weight-average molecular weight (Mw) of the oligomers prepared in the oligomer preparation step can typically be between 200 and 50,000. A preferred lower limit that can be combined with the above range is 300 or more, more preferably 400 or more. A preferred upper limit that can be combined with the above range is 45,000 or less, more preferably 40,000 or less. Having the weight-average molecular weight of the oligomer within these ranges makes it easier to ensure the mechanical strength of the pellicle film. The weight-average molecular weight can be determined based on a chromatogram measured by gel permeation chromatography (GPC).

[0057] <<GPC Conditions>> In this disclosure, the weight-average molecular weight can be obtained, for example, using the following GPC conditions: Column: TSKgel G2000HXL & TSKgel G4000HXL (manufactured by Tosoh Corporation) Column temperature: 40°C Mobile phase: Tetrahydrofuran (THF) Flow rate: 0.65 mL / min Detection device: RI Standard substance: Polystyrene

[0058] ≪Various Configurations≫ The thickness of this pellicle film may be 0.10 μm or more and 10.0 μm or less, preferably 0.20 μm or more, more preferably 0.25 μm or more, and also preferably 6.0 μm or less, more preferably 3.0 μm or less. When the thickness is within the above range, it is easier to further ensure light transmittance, mechanical strength, and light resistance of the pellicle film.

[0059] The transmittance of this pellicle film to light with a wavelength of 193 nm is, for example, 80% to 100%, preferably 90% or more, and more preferably 95% or more. In one embodiment, such transmittance is, for example, 80.0% to 100.0%, preferably 90.0% or more, and more preferably 95.0% or more. The transmittance can be measured based on the method described in the examples.

[0060] The transmittance of this pellicle film to light with a wavelength of 248 nm is, for example, 80% to 100%, preferably 90% or more, and more preferably 95% or more. The transmittance can be measured based on the method described in the examples.

[0061] The transmittance of this pellicle film to light with wavelengths between 290 nm and 385 nm is, for example, 80% to 100%, preferably 90% or more, and more preferably 95% or more. The transmittance can be measured based on the method described in the examples.

[0062] The transmittance of this pellicle film for light with wavelengths between 360 nm and 440 nm is, for example, 80% to 100%, preferably 90% or more, and more preferably 95% or more. The transmittance can be measured based on the method described in the examples.

[0063] The pellicle film may consist solely of a layer containing the polysilsesquioxane, or it may include layers other than the polysilsesquioxane layer (hereinafter referred to as "other layers"). Examples of other layers include layers with a lower refractive index than the polysilsesquioxane layer (e.g., an anti-reflective layer). Including an anti-reflective layer makes it easier to improve the light transmittance of the pellicle film.

[0064] Examples of materials for the anti-reflective layer include fluorinated polymers {tetrafluoroethylene-vinylidene fluoride-hexafluoropropylene ternary copolymer, polymers with a cyclic structure in the main chain such as DuPont's Teflon® AF (trade name), Asahi Glass's Cytop (trade name), Ausimont's Algoflon (trade name), polyfluoroacrylate, etc.}, calcium fluoride, magnesium fluoride, barium fluoride, etc.

[0065] The anti-reflective layer may be a polymer layer mainly containing polymers, or an inorganic layer mainly containing inorganic materials. Methods for forming the anti-reflective layer include spin coating for polymer layers, and thin-film formation methods such as vacuum deposition and sputtering for inorganic layers.

[0066] The pellicle film may have an uneven surface. Having such a shape makes it easier to improve the light transmittance of the pellicle film. Preferably, the shape of the protrusions in the uneven structure is a polygonal pyramidal shape, a conical shape, a truncated polygonal pyramidal shape, or a truncated cone shape. A pellicle film having an uneven surface can be manufactured by depositing the pellicle film onto a substrate having an uneven surface, or onto a film having an uneven surface.

[0067] ≪Method for Manufacturing the Pellicle Film≫ As for the manufacturing method of this pellicle film, known pellicle film manufacturing methods and manufacturing conditions may be appropriately adopted. One method is to deposit a solution in which this polysilsesquioxane can be dissolved and / or dispersed onto a substrate and then dry it. Examples of film deposition methods include spin coating, roll coating, knife coating, and casting, with spin coating being preferred. Examples of drying methods include heating with a hot plate, clean oven, infrared rays, far infrared rays, etc.

[0068] Examples of substrates used for film deposition include synthetic quartz, fused silica, alkali-free glass, low-alkali glass, soda-lime glass, and silicon wafers. The coefficient of linear expansion of the substrate between 0°C and 300°C is 50 × 10⁻⁶. －７It is preferable that the temperature is m / °C or lower. Furthermore, the surface of the substrate used for film deposition may be treated with a release agent.

[0069] ≪Pellicle≫ The pellicle of this disclosure (hereinafter sometimes abbreviated as "this pellicle") comprises a frame and a pellicle film attached to the frame.

[0070] A preferred embodiment of the pellicle will be described below. Figures 1(a) and 1(b) show an example of the configuration of the pellicle 1 of the present disclosure. Figure 1(a) is a perspective view of the pellicle 1, and Figure 1(b) is a cross-sectional view taken along line A-A in Figure 1(a). In the figures, the x-direction, y-direction, and z-direction are shown to be orthogonal to each other, and these directions correspond in Figures 1(a) and 1(b). Figure 1(b) also shows a photomask M to which the pellicle 1 is attached along the direction of the arrow.

[0071] As shown in the figure, the pellicle 1 comprises a frame 2 and a pellicle film 3 attached to the frame 2. The pellicle 1 can be attached to the photomask M so as to surround a circuit pattern (not shown) drawn on the photomask M. Therefore, the size and shape of each component in the pellicle 1 may be appropriately selected according to the photomask M and the circuit pattern drawn on the photomask M.

[0072] (Pellicle film) The pellicle film 3 is stretched and attached to the frame 2. Here, in the pellicle 1, the above-described pellicle film is used as the pellicle film 3. Accordingly, this disclosure provides a pellicle 1 that is highly practical in terms of the permeability of the pellicle film 3, the mechanical strength of the pellicle film 3, and / or the light resistance of the pellicle film 3.

[0073] (Frame) The frame 2 has a pair of long sides 2a and a pair of short sides 2b, and therefore, in a plan view (projection view along the direction of arrow z), a rectangular opening Op is formed with these long sides 2a and short sides 2b as edges.

[0074] For small pellicles, the length of the long side 2a may be between 110 mm and 180 mm, and the length of the short side 2b may be between 100 mm and 150 mm. For large pellicles, the length of the long side 2a may be between 400 mm and 2500 mm, and also between 800 mm and 1200 mm, and the length of the short side 2b may be between 300 mm and 2000 mm, 400 mm and 400 mm and 400 mm.

[0075] The widths of the long side 2a and the short side 2b may be 1.8 mm or more and 30 mm or less, preferably 1.9 mm or more, more preferably 2.0 mm or more, preferably 25 mm or less, and more preferably 19 mm or less.

[0076] The thickness of the long side 2a and the short side 2b may be 2.0 mm or more and 10 mm or less, preferably 2.3 mm or more, preferably 8.0 mm or less, and more preferably 7.0 mm or less.

[0077] The cross-sectional shapes of the long side 2a and the short side 2b can be rectangular, H-shaped, and T-shaped, respectively. In this embodiment, the long side 2a and the short side 2b are each taken to have an outer shape that is approximately a rectangular parallelepiped, and therefore the cross-sectional shapes of the long side 2a and the short side 2b are rectangular.

[0078] The material for frame 2 may be aluminum, aluminum alloys (5000 series, 6000 series, 7000 series, etc.); iron and iron-based alloys; ceramics (SiC, AlN, Al ２ O ３ (etc.); composite materials of ceramics and metals (Al-SiC, Al-AlN, Al-Al ２ O ３ Examples include: carbon steel; tool steel; stainless steel series; magnesium alloys; polycarbonate resin, acrylic resin, and other resins.

[0079] The frame 2 preferably has ventilation holes 4 that penetrate the inside and outside of the space formed between the pellicle 1 and the photomask M when the pellicle 1 is attached to the photomask M, in order to reduce the pressure difference between the inside and outside of the space formed between the pellicle 1 and the photomask M. The size and number of ventilation holes 4 may be determined based on the volume of the space, etc. If the pellicle 1 has ventilation holes 4, it is preferable that the frame 2 has a filter 5 such as a porous membrane that covers the ventilation holes 4, from the viewpoint of easily preventing foreign matter from entering the space.

[0080] The frame 2 preferably includes a film adhesive layer 6 for bonding the pellicle film 3. The film adhesive layer 6 can be placed on one surface of the frame 2, particularly the surface to which the pellicle film 3 is bonded, and the presence of the film adhesive layer 6 makes it easier to support the pellicle film 3 in a stretched state. The film adhesive layer 6 may be formed by applying a film adhesive to the frame 2, and in this case, examples of film adhesives include epoxy, acrylic, silicone, and fluorine-based adhesives. The film adhesive can be cured as needed, and in this case, examples of curing methods for the adhesive include thermosetting, photocuring, and anaerobic curing.

[0081] The frame 2 preferably includes a mask adhesive layer 7 for attaching to the photomask M. The mask adhesive layer 7 can be located on the other side of the frame 2, particularly the side that attaches to the photomask M. The presence of the mask adhesive layer 7 facilitates the fixing and detachment of the pellicle 1 to the photomask M. The mask adhesive layer 7 may be formed by applying a mask adhesive to the frame 2. In this case, examples of mask adhesives include hot-melt types (rubber-based and acrylic-based), solvent-based types (acrylic-based and silicone-based), and the like.

[0082] A tape-shaped adhesive member may be used as the mask adhesive layer 7. The tape-type adhesive member has, for example, an adhesive layer on both sides of the base material. As the base material, for example, acrylic and PVC sheets, or rubber, polyolefin, and urethane foams can be used, and as the adhesive layer, for example, a layer containing an adhesive such as rubber, acrylic, or silicone can be used.

[0083] <Resin composition for pellicle film> A further aspect of the present invention is a resin composition for pellicle film comprising a polysilsesquioxane having a random structure. The polysilsesquioxane having a random structure is as described above. The resin composition may or may not contain a solvent, solvent or volatile component, and may be in any form, for example, liquid, solid, pelletized, etc.

[0084] [Other Embodiments] This embodiment is not limited to the above-described form, and various modifications are possible within the scope of its gist.

[0085] For example, the frame may have any external and internal shape for attaching the pellicle film and for enclosing the circuit pattern drawn on the photomask. The frame may be configured to be separable. The pellicle may be fixed to the photomask by any jig, in which case the frame may have any shape corresponding to the jig.

[0086] The pellicle film may be pressed onto the frame or bonded with a film adhesive layer. In another example, a method for protecting a photomask is also provided, characterized by attaching the pellicle film according to the present disclosure to the surface of the photomask and performing exposure using short-wavelength light (for example, light with wavelengths such as 190 nm to 440 nm, 290 nm to 440 nm, 193 nm to 248 nm, etc.).

[0087] The embodiments of this disclosure will be described below with reference to examples and comparative examples. However, the embodiments of this disclosure are not limited to the following examples.

[0088] [Examples and Comparative Examples] <Example 1> A constituent unit represented by formula (T) (wherein R ３ A polysilsesquioxane containing a methyl group and having a content of 100% of its constituent units was dissolved in butyl acetate to a concentration of 70% by mass, thereby obtaining a polysilsesquioxane solution for pellicle film preparation. The pellicle film was then prepared as follows.

[0089] The polysilsesquioxane solution was spin-coated onto an ETFE film fixed to a quartz substrate with double-sided tape at a rotational speed of 1500 rpm, thereby obtaining a polysilsesquioxane thin film on the film. The thin film on the film was dried in a fully exhausted oven at 120°C for 2 hours to remove the solvent. Subsequently, the thin film was peeled off the film using tape to obtain a polysilsesquioxane pellicle film (i.e., polysilsesquioxane with a random structure). The thickness of the obtained pellicle film was 6.0 μm. Furthermore, the obtained pellicle film could be stretched and adhered to a frame to produce a pellicle.

[0090] <Example 2> In this example, a polysilsesquioxane solution having a random structure was prepared as follows.

[0091] First, 25 g of pure water, 100 g of 2-propanol, and 0.2 g of 35% hydrochloric acid were added to a four-necked flask. Then, 12.5 g (20 mol%) of diethoxydimethylsilane, 30.0 g (40 mol%) of methyltriethoxysilane, 27.5 g (30 mol%) of (3,3,3-trifluoropropyl)triethoxysilane, and 8.7 g (10 mol%) of tetraethoxysilane were added dropwise. The solution in the flask was stirred at 40°C for 3 hours, then 6 g of pure water and 1 g of 35% hydrochloric acid were added and the mixture was stirred at 80°C for 12 hours. A mixture was obtained.

[0092] The resulting mixture was separated and washed with 170 g of butyl acetate and 170 g of pure water, during which the butyl acetate phase was washed with pure water until the pH was 4 or higher. 10 g of methyl isobutyl ketone was further mixed into the resulting solution, and the mixture was concentrated under reduced pressure to obtain a methyl isobutyl ketone solution of polysilsesquioxane. Subsequently, 30 g of 2-propanol was further mixed in, and the mixture was stirred at 25°C for 1 hour. The resulting solution was filtered using a depth filter to remove precipitates, and then concentrated under reduced pressure to a concentration of 70% by mass. This yielded a methyl isobutyl ketone solution of polysilsesquioxane (i.e., polysilsesquioxane with a random structure) in 97% yield.

[0093] The obtained polysilsesquioxane had a weight-average molecular weight Mw of 2,200, a number-average molecular weight Mn of 1,700, and a molecular weight distribution Mw / Mn of 1.29. Using the obtained polysilsesquioxane solution, a pellicle film was prepared at a drying temperature of 80°C in the same manner as in Example 1. The thickness of the obtained pellicle film was 6.0 μm. This example was carried out with reference to the method disclosed in the publication (Japanese Patent Application Publication No. 2020-015780). Furthermore, the measurements of the weight-average molecular weight Mw and the number-average molecular weight Mn were performed according to the methods disclosed in the same publication.

[0094] <Example 3> In this example, a polysilsesquioxane solution having a random structure was prepared as follows.

[0095] First, 25 g of pure water, 100 g of 2-propanol, and 0.2 g of 35% hydrochloric acid were added to a four-necked flask. Then, 10.0 g (20 mol%) of diethoxydimethylsilane, 30.0 g (50 mol%) of methyltriethoxysilane, and 22.0 g (30 mol%) of (3,3,3-trifluoropropyl)triethoxysilane were added dropwise. The solution in the flask was stirred at 40°C for 3 hours, then 6 g of pure water and 1 g of 35% hydrochloric acid were added and the mixture was stirred at 80°C for 12 hours. A mixture was obtained.

[0096] The resulting mixture was separated and washed with 170 g of butyl acetate and 170 g of pure water, during which the butyl acetate phase was washed with pure water until the pH was 4 or higher. 10 g of methyl isobutyl ketone was further mixed into the resulting solution, and the mixture was concentrated under reduced pressure to obtain a methyl isobutyl ketone solution of polysilsesquioxane. Subsequently, 30 g of 2-propanol was further mixed in, and the mixture was stirred at 25°C for 1 hour. The resulting solution was filtered using a depth filter to remove precipitates, and then concentrated under reduced pressure to a concentration of 70% by mass. This yielded a methyl isobutyl ketone solution of polysilsesquioxane (i.e., polysilsesquioxane with a random structure) in 90% yield.

[0097] The weight-average molecular weight Mw of the obtained polysilsesquioxane was 5,800. Using the obtained polysilsesquioxane solution, a pellicle film was prepared at a drying temperature of 80°C in the same manner as in Example 1. The thickness of the obtained pellicle film was 6.0 μm. This example was carried out with reference to the method disclosed in the publication (Japanese Patent Application Publication No. 2020-015780). The measurement of the weight-average molecular weight Mw was also carried out according to the method disclosed in the same publication.

[0098] <Example 4> In a 300 mL four-necked flask, 19.9 g (41 mol%) of diethoxydimethylsilane, 28.6 g (49 mol%) of methyltriethoxysilane, 56.0 g of methyl isobutyl ketone (MIBK), and 0.37 g of pure water were charged. Then, a mixture of 2.0 g (5 mol%) of trimethoxysilane and 5.0 g of MIBK was added dropwise over 0.5 hours at 25°C. Next, 1.3 g (2.5 mol%) of hexamethyldisiloxane and 0.32 g of 2 mol / L hydrochloric acid were charged and the mixture was reacted at 25°C for 24 hours. After that, 23.1 g of MIBK was charged and removed by distillation under reduced pressure to obtain 39 g of MIBK solution of polysilsesquioxane (i.e., polysilsesquioxane with a random structure) with a solid content of 51% by mass. The yield was 87%.

[0099] The obtained polysilsesquioxane had a weight-average molecular weight Mw of 46,000, a number-average molecular weight Mn of 2,800, and a molecular weight distribution Mw / Mn of 16.4. Using the obtained polysilsesquioxane solution, a pellicle film was prepared at a drying temperature of 200°C in the same manner as in Example 1. The thickness of the obtained pellicle film was 6.0 μm.

[0100] <Comparative Example 1> Fluororesin Pellicle Film Instead of the polysilsesquioxane solution used in Example 1, a solution was prepared by diluting fluororesin (AGC Corporation, Cytop CTX-809SP2: trade name) with a fluorine solvent (AGC Corporation, Cytop CT-SLV: trade name), and a pellicle film was prepared in the same manner as in Example 1. The thickness of the obtained pellicle film was 0.3 μm.

[0101] <Comparative Example 2> Cellulose Pellicle Film Instead of the polysilsesquioxane solution used in Example 1, an ethyl lactate solution of cellulose acetate propionate (Eastman Chemical Company, CAP480-20: trade name) was used, and a pellicle film was prepared on a quartz substrate in the same manner as in Example 1. The thickness of the obtained pellicle film was 4.0 μm.

[0102] <Comparative Example 3> Polyladdersiloxane Pellicle Film In Comparative Example 1, instead of the polysilsesquioxane solution, a polyladdersiloxane solution prepared according to a known method disclosed in Example 1 of the publication (Japanese Patent Publication No. 4-166840) was used, and a pellicle film was fabricated on a quartz substrate in the same manner as in Example 1. The thickness of the obtained pellicle film was 3.0 μm. The polyladdersiloxane obtained in Comparative Example 3 {polysiloxane with ladder structure} is given by the following formula: {In the formula, R ２１ , R ２２ , and n are the groups and integers corresponding to the structure of the polyladdersiloxane obtained by Example 1 of the above publication (Japanese Patent Publication No. 4-166840). It is presumed to have a regularly arranged siloxane skeleton as illustrated in ).

[0103] [Measurement and Evaluation] <Transmittance Measurement Test> Using a UV-Vis spectrophotometer (UV-1900i, manufactured by Shimadzu Corporation), the transmittance (%) of each pellicle film in the examples and comparative examples was measured for light at wavelengths of 193 nm, 248 nm, and 365 nm.

[0104] <Exposure Test> Each pellicle film of the examples and comparative examples was stretched and attached to an aluminum frame (inner diameter 24 x 29 mm, and outer diameter 35 x 40 mm) to obtain test specimens. The obtained test specimens were irradiated with VUV light at an irradiation distance of 69 mm or 9 mm and an irradiation time of 30 seconds or 1 minute, according to the conditions in the table below. The irradiation conditions for the VUV light were as follows: (Irradiation conditions) ・Light source: Xe ・Illuminance: 50 mW / cm ２ Oxygen concentration: 1000 ppm

[0105] <Puncture Test> After the <Exposure Test> described above, the pellicle film was attached to an aluminum frame with a circular hole of 7 mm in diameter using double-sided tape, covering the hole, in an attempt to obtain a test specimen. If a test specimen was obtained, a tensile testing machine was used to apply a load to the specimen until the pellicle film broke, and the load (gf; maximum test force) at the time of breakage was calculated. The maximum test force was calculated over four trials (n=4), and the average values ​​obtained are shown in the table below. The maximum test force was calculated according to the following equipment and conditions. (Equipment and conditions) ・Equipment name: Autograph (SHIMAZU EZ-S, manufactured by Shimadzu Corporation) ・Load cell: 10N ・Crosshead speed: 5 mm / min ・Temperature: 21℃ ・Humidity: 50%

[0106]

[0107] As can be seen from the table above, the pellicle film of the example was found to exhibit excellent transmittance to light with wavelengths suitable for photolithography, and to ensure mechanical strength and / or light resistance.

[0108] One aspect of the present invention, a pellicle film and a pellicle, can be used for dust protection of photomasks and the like in photolithography processes for forming semiconductors, LSIs, thin-film transistors (TFTs), color filters (CFs), etc., which constitute flat panel displays (FPDs). It is suitable for lithography using ultraviolet light with ArF line (193 nm), KrF line (248 nm), j line (313 nm), i line (365 nm), h line (405 nm), or a combination of these as the exposure light source.

[0109] 1: Pellicle 2: Frame 2a: Long side 2b: Short side 3: Pellicle membrane 4: Ventilation holes 5: Filter 6: Membrane adhesive layer 7: Mask adhesive layer M: Photomask Op: Opening

Claims

1. A pellicle membrane containing polysilsesquioxane having a random structure.

2. The polysilsesquioxane is given by the following formula (T): {In the formula, R ３ The pellicle film according to claim 1, comprising a structural unit represented by}.

3. The pellicle film according to claim 2, wherein the content of the constituent unit represented by formula (T) in the polysilsesquioxane is 20 mol% or more and 85 mol% or less.

4. The polysilsesquioxane is given by the following formula (D): {In the formula, R ２ Each independently represents a hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom (-H) which may have substituents comprising at least one functional group selected from the group consisting of a halogen group, an oxa group (-O-), a carbonyl group (>C=O), and an epoxy group. The pellicle film according to claim 1, comprising a structural unit represented by}.

5. The pellicle film according to claim 4, wherein the content of the constituent unit represented by formula (D) in the polysilsesquioxane is 1 mol% or more and 60 mol% or less.

6. The polysilsesquioxane is given by the following formula (Q): The pellicle film according to claim 1, comprising a constituent unit represented by [the specified unit].

7. The pellicle film according to claim 6, wherein the content of the constituent unit represented by formula (Q) in the polysilsesquioxane is 0 mol% or more and 25 mol% or less.

8. The polysilsesquioxane is given by the following formula (M): {In the formula, R 1 Each independently represents a hydrocarbon group having 1 to 20 carbon atoms or a hydrogen atom (-H) which may have substituents comprising at least one functional group selected from the group consisting of a halogen group, an oxa group (-O-), a carbonyl group (>C=O), and an epoxy group. The pellicle film according to claim 1, comprising a structural unit represented by}.

9. The pellicle film according to claim 8, wherein the content of the constituent unit represented by formula (M) in the polysilsesquioxane is 0 mol% or more and 10 mol% or less.

10. The constituent unit represented by the above formula (T) is given by the following formula (T1): (In the formula, R ３１ The pellicle film according to claim 2, comprising a constituent unit represented by (where represents a hydrocarbon group having 1 to 10 carbon atoms that includes a halogen group).

11. The pellicle film according to claim 1, wherein the transmittance to light with a wavelength of 193 nm is 80% or more.

12. The pellicle film according to claim 1, wherein the transmittance to light with a wavelength of 248 nm is 80% or more.

13. The pellicle film according to claim 1, wherein the transmittance to light with a wavelength of 365 nm is 80% or more.

14. A pellicle having the pellicle film described in any one of claims 1 to 13.

15. A resin composition for pellicle films comprising polysilsesquioxane having a random structure.

16. A method for protecting a photomask, characterized by attaching a pellicle film according to any one of claims 1 to 13 to the surface of a photomask and performing exposure using short-wavelength light.

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