JP2576581B2 - High light-transmitting dust-proof film and method of manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a highly light-transmitting dustproof film having an antireflection layer used for a pellicle as a dustproof cover of a photomask or a reticle.

[Conventional technology]

In a semiconductor exposure process, a method has been proposed in which a dustproof film called a pellicle is used in combination with a photomask or a reticle to prevent dust from affecting the exposure process and improve productivity (Japanese Patent Publication No. Sho 54). −28716
issue). The pellicle has a structure in which a dust-proof film is provided on one side of the pellicle frame, and is used by being superposed on a photomask or a reticle.

Conventionally, a single-layer thin film of nitrocellulose is mainly used as a dustproof film constituting such a pellicle, but a high-refractive-index polymer and a low-refractive-index polymer are formed on a transparent thin film of nitrocellulose for the purpose of improving the throughput in the exposure step. Dustproof films provided with an antireflection layer comprising a laminated film of a refractive index polymer have been proposed (JP-A-60-237450, JP-A-61-53601, JP-A-61-209449, and JP-A-61-209449). −127
No. 801).

Here, polystyrene, polysulfone, polyethersulfone, polyphenylene ether, polycarbonate, aromatic polyester and the like are mentioned as the high refractive index polymer forming the antireflection layer. These substances are used to form the antireflection layer. Even with a low refractive index, 40
Only a dustproof film having a large difference between the maximum light transmittance and the minimum light transmittance of 0 to 450 nm can be obtained.

JP-A-62-127801 discloses polyvinyl naphthalene as a high-refractive-index polymer.However, when polyvinyl naphthalene is applied and a fluorine-capped polymer is coated as a low-refractive-index polymer, a layer of polyvinyl naphthalene is peeled off. There is a disadvantage that.

As a low refractive index polymer, JP-A-60-237450 describes that a fluorine-based polymer or a silicon-based polymer is used as an anti-reflection layer. It is a fluoroethylene / vinylidene fluoride copolymer or a tetrafluoroethylene / vinylidene fluoride / hexafluoropropylene copolymer. JP-A-61-53601
Also discloses that a fluorine-based polymer or a silicon-based polymer can be used as the anti-reflection layer, but the specific examples of the fluorine-based polymer include tetrafluoroethylene / vinylidene fluoride / hexafluoropropylene copolymer It is. JP-A-61-209449 discloses that a fluoropolymer containing polyfluoro (meth) acrylate can be used as an antireflection layer, but the specific description is made of tetrafluoroethylene as described above. / Vinylidene fluoride / hexafluoropropylene polymer.

However, when an antireflection layer is formed by laminating a high-refractive-index polymer and a low-refractive-index polymer as described above, the range in which a high light transmittance can be obtained is narrow, and foreign matter is generated due to peeling and destruction of the high-refractive index polymer. There was a problem.

[Problems to be solved by the invention]

An object of the present invention is to provide a high light-transmitting dustproof film having a wide range in which a high light transmittance can be obtained by laminating a high refractive index polymer and a low refractive index polymer to solve the above problems.

Another object of the present invention is to propose a method capable of preventing the peeling and destruction of a high refractive index polymer and producing a dustproof film having high light transmittance.

[Means for solving the problem]

The present invention relates to the following highly light-transmitting dustproof film and a method for producing the same.

(1) a three-layer structure consisting of a low-refractive-index polymer / high-refractive-index polymer / substrate in which a high-refractive-index polymer is coated on one or both sides of a substrate made of a transparent thin film, and a low-refractive-index polymer is further coated thereon, or In a five-layer high light-transmitting dustproof film composed of a low refractive index polymer / high refractive index polymer / substrate / high refractive index polymer / low refractive index polymer,
As a high refractive index polymer, the general formula (Wherein R ¹ is —CH ＝ CH ₂ or It is. And at least one naphthalene derivative monomer selected from (Wherein R ² is —CH ＝ CH ² , Or R ³ is H, an alkyl group having 1 to 10 carbon atoms, It is. A highly light-transmitting dustproof film characterized by using a 95/5 to 60/40 (molar ratio) copolymer with at least one benzene derivative monomer selected from the group consisting of:

(2) The highly light-transmitting dustproof film according to (1), wherein the substrate is a cellulose derivative.

(3) The low refractive index polymer has the general formula (Wherein, R ⁴ is H or —CH ₃ , and R ⁵ is a fluoroalkyl group optionally containing an ether oxygen atom therebetween.) A fluorine-containing poly (meta) containing at least one monomer selected from the group consisting of ) The highly light-transmitting dustproof film according to the above (1) or (2), which is an acrylate.

(4) A solution prepared by dissolving a high-refractive-index polymer in a solvent having a boiling point of 120 to 200 ° C. is supplied on a substrate to form a film by a rotary film-forming method, and then a low-refractive-index polymer solution is supplied thereon. And the expression (In the formula, M is the molecular weight of the high refractive index polymer.) The method according to any one of the above (1) to (3), wherein the multilayer film is formed by a rotary film forming method at the following rotation speed. For producing a highly light-transmitting dust-proof film.

The alkyl group represented by R ³ in the above general formula _{(II), -CH 3, -CH 2 CH 3} , -CH 2 CH 2 CH 3, _{-CH 2 CH 2 CH 2 CH 3} , etc. _{-CH 2 CH 2 CH 2 CH 2} CH 2 CH 3 and the like.

In the present invention, the substrate serving as the main body of the dust-proof film is formed of a transparent thin film, and may be any material that does not absorb light at a wavelength of 350 to 450 nm used for exposure, but may be nitrocellulose, ethyl cellulose, or cellulose propionate. ,
A cellulose derivative thin film such as acetyl cellulose is preferred. Among these, nitrocellulose is preferable from the viewpoint of film strength. Nitrocellulose is 11-12.5%, especially 1
1.5 to 12.2% nitrification degree (N%), and 150,000 to 350,00
0, especially an average molecular weight of 170,000-320,000 (weight average,
Those having w) are preferred. The thickness of the substrate is free from the viewpoint of the light transmittance, but the thickness is preferably 5 μm or less since the thicker the substrate, the greater the aberration at the time of exposure.

The refractive index of the high refractive index polymer and the specific refractive index polymer coated on one or both sides of the base material is n, the refractive index of the high refractive index polymer is n ₁ , and the refractive index of the low refractive index polymer is n. If n ₂ N ₁ and n ₂ represented by are preferred. For example, if the substrate is a nitrocellulose, a n = 1.5, the refractive index n ₂ of the current commonly available low refractive index polymer is refracted because it is from 1.35 to 1.36, the high refractive index polymers corresponding thereto The rate is 1.
65 to 1.67. There is a vinyl naphthalene polymer as a high refractive index polymer that satisfies such conditions, but when applying or processing a low refractive index polymer on the vinyl naphthalene polymer, the vinyl naphthalene polymer is destroyed and cannot be used because it becomes dust. .

In the present invention, the high refractive index polymer coated on one or both sides of the substrate is a naphthalene derivative monomer represented by the general formula (I) and a benzene derivative monomer represented by the general formula (II) of 95/5 to 60 / 40 (molar ratio) copolymer which satisfies the above refractive index is obtained. The naphthalene derivative monomer and the benzene derivative monomer can be copolymerized alone or in combination of two or more. When the molar ratio between the naphthalene derivative monomer and the benzene derivative monomer is less than 95/5, the high refractive index polymer is destroyed when the low refractive index polymer is applied. No permeability is obtained.

The low-refractive-index polymer to be further laminated and coated on the high-refractive-index polymer layer coated on one or both sides of the base material includes at least one monomer selected from the general formula (III), and Fluorine-containing poly (meth) acrylate having a fluorine content of 50% by weight or more is preferable.

R ⁵ in the general formula (III) has 2 to 1 carbon atoms
4 is preferably a fluoroalkyl group which may contain an ether oxygen atom in between, specifically, -CH ₂ CF ₃ , -CH _{2
C 2 F 5, -CH 2 C} 3 F 7, -CH 2 C 4 F 9, -CH 2 C 5 F 11, -CH 2 C 7 F 15, -C
_{H 2 C 8 F 17, -CH} 2 C 9 F 19, -CH 2 C 10 F 21, -CH 2 CH 2 CF 3, -CH 2 CH
₂ C ₂ F ₅ , −CH ₂ CH ₂ C ₃ F ₇ , −CH ₂ CH ₂ C ₄ F ₉ , −CH ₂ CH ₂ C ₅ F ₁₁ , −CH
₂ CH ₂ C ₇ F ₁₅ , −CH ₂ CH ₂ C ₈ F ₁₇ , −CH ₂ CH ₂ C ₉ F ₁₉ , −CH ₂ CH ₂ C ₁₀ F
_{21, -CH 2 (CF 2)} 2 H, -CH 2 (CF 2) 4 H, -CH 2 (CF 2) 6 H, -
CH ₂ (CF ₂ ) ₈ H, -CH ₂ (CF ₂ ) ₁₀ H, CH (CF ₃ ) ₂ , -CH ₂ CF ₂ CH
FCF ₃ , -CH ₂ CF ₂ CHF (CF ₂ ) ₆ H, -CH ₂ -CF (CF ₃ ) CHFCF (C
_{F 3) 2, -CH 2 CF} (C 2 F 5) CH (CF 3) 2, -CH 2 C 6 HF 12, -C 6 HF
₁₂ , -CH ₂ C ₁₀ HF ₂₀ , -CH ₂ -C ₅ F ₈ H,-(CH ₂ ) ₅ OCF (C
F ₃ ) ₂ , − (CH ₂ ) ₁₁ OCF (CF ₃ ) ₂ , −CH ₂ (CF ₂ ) ₂ OCF ₃ , −C
_{H 2 (CF 2) 2 OC} 2 F 5, -CH 2 (CF 2) 2 OC 3 F 7, And the like.

Fluorine-containing poly (meth) acrylate is the above monomer 1
It may be a homopolymer of one kind or a copolymer of two or more kinds. In the case of a copolymer, a linear fluoroalkyl group containing no ether oxygen atom, and a linear fluoroalkyl group containing an ether oxygen atom or a branched fluoroalkyl group that may contain an ether oxygen atom, Is preferable because the light transmittance increases.

Further, the fluorinated poly (meth) acrylate may be a copolymer of the monomer of the general formula [III] and another monomer. The other monomer to be copolymerized with the monomer of the general formula (III) is not particularly limited, (Wherein, R ⁶ is H or —CH ³ , and R ⁷ is an alkyl group which may contain an ether oxygen atom).

As R ⁷ in the general formula [V], an alkyl group having 1 to 50 carbon atoms, preferably 4 to 24 carbon atoms is preferable, and specifically,
_{-CH 3, -C 2 H 5,} -C 4 H 9, -C 6 H 13, -C 8 H 17, -C 9 H 19, -C 10 H
₂₁ , -C ₁₂ H ₂₅ , -C ₁₇ H ₃₅ , -C ₁₈ H ₃₇ , -C ₂₄ H ₄₉ , -C ₃₄ H _{69 and the} like, and may contain an ether oxygen atom.

The mixing ratio of the other monomer such as the alkyl group-containing (meth) acrylate of the general formula [V] combined with the fluorine-containing (meth) acrylate monomer of the general formula [III] is 70 mol% or less, preferably 1 to 20 mol%. Is preferred.

The fluorine-containing poly (meth) acrylate preferably has a polymer fluorine content of 50 to 70% by weight. When it is in the above range, a layer that is transparent and does not cause color unevenness or whitening due to disorder between layers can be obtained. The fluorine content in the polymer is 50
When the content is less than the weight percentage, the refractive index increases, and a film having a preferable light transmittance cannot be obtained.

The high-refractive-index polymer and the low-refractive-index polymer serving as the antireflection layer are respectively formed on one or both sides of a substrate made of a transparent thin film such as a cellulose derivative, and are composed of a low-refractive-index polymer / high-refractive-index polymer / substrate. A highly light-transmitting dustproof film having a three-layer structure or a five-layer structure composed of a low refractive index polymer / high refractive index polymer / substrate / high refractive index polymer / low refractive index polymer is formed. The thickness of each of the high refractive index polymer and the low refractive index polymer is preferably / 4n (n is a refractive index) of the wavelength of the target light.

The method for producing a highly light-transmitting dustproof film having an antireflection layer according to the present invention comprises the steps of: supplying a solution of a high refractive index polymer to one or both surfaces of a substrate formed by a spinning method using a spinner; After the production by the method, a solution of a low-refractive index polymer is supplied thereon, and the film is laminated by a rotational film-forming method at a rotational start-up speed of the formula [IV] or lower.

For example, a three-layered single-sided antireflection type dustproof film using a cellulose derivative as a substrate is produced as follows.
That is, first, a cellulose derivative solution is supplied onto a smooth substrate such as glass attached to a spinner, and the spinner is rotated to form a substrate made of a transparent thin film of the cellulose derivative by a rotary film forming method. The cellulose derivative is dissolved in a solvent, and a purified solution such as filtration is used. As the solvent, methyl ethyl ketone, methyl isobutyl ketone,
Ketones such as methyl ethyl ketone and acetone, lower fatty acid esters such as butyl acetate and isobutyl acetate, and a mixed solvent of the aforementioned ketone or ester and isopropyl alcohol are used. The thickness of the formed base material can be appropriately changed by changing the solution viscosity or the rotation speed of the substrate.

The substrate made of the cellulose derivative transparent thin film formed on the substrate is dried by means such as hot air irradiation or infrared lamp irradiation to remove the residual solvent.

Next, a solution of the high refractive index polymer is supplied onto the dried substrate, and the spinner is rotated again to form a high refractive index polymer layer by a rotary film forming method. The solvent for dissolving the high refractive index polymer has a boiling point of 120 to 200 ° C., preferably 130 to 1
A solvent at 80 ° C. that can dissolve the high refractive index polymer and does not dissolve or swell the substrate is preferable. As such a solvent, for example, xylene, ethylbenzene, cumene, pseudocumene and the like can be used, and ethylbenzene is particularly preferable. The concentration of the high refractive index polymer solution is preferably 0.5 to 4% by weight.

Next, a low-refractive-index polymer solution is supplied onto the high-refractive-index polymer layer dried in the same manner as described above, and a spinner is rotated at a rotational start-up speed of the formula (IV) or lower, and the low-refractive index is formed by a rotary film forming method. Form a refractive index polymer layer. The solvent that dissolves the low refractive index polymer can dissolve the low refractive index polymer,
A solvent that does not dissolve or swell the high refractive index polymer and the substrate, preferably having a boiling point of 40 to 220 ° C, preferably 60 to 150 ° C, for example, xylene hexafluoride,
Benzotrifluoride, propanol pentafluoride and the like can be used. The concentration of the low refractive index polymer solution is preferably from 0.3 to 3% by weight. At this time, by setting the spinning speed of the spinner to be equal to or less than the formula [IV], peeling and destruction of the high refractive index polymer layer are prevented, and an antireflection layer having high light transmittance is formed.

Next, after drying in the same manner as described above, the substrate on which the antireflection layer is formed is peeled off from the substrate to obtain a dustproof film having a three-layer structure.

The dustproof film having antireflection layers on both sides of the base material is obtained by reversing the three-layer structure dustproof film obtained above and attaching it to a spinner, and by the same operation as described above, a high refractive index is applied to the layer on the opposite side of the base material. It is manufactured by layer coating of a high refractive index polymer and a low refractive index polymer.

The dustproof film thus manufactured has a wide range in which a high light transmittance can be obtained. For a three-layer dustproof film, the maximum transmittance of 400 to 450 nm is 96% or more and the minimum transmittance is 95% or more. For a five-layer structure, the maximum transmittance is 100% and the minimum transmittance is 99.5% or more. Although required, the dustproof film produced by the present invention can satisfy the requirement.

〔The invention's effect〕

As described above, the dustproof film of the present invention has a wide range in which high light transmittance can be obtained. Further, according to the production method of the present invention, it is possible to produce a dustproof film having a high light transmittance by preventing peeling and destruction of the high refractive index polymer.

〔Example〕

Hereinafter, examples of the present invention will be described. A methyl isobutyl ketone solution of a cellulose derivative was dropped on a quartz substrate attached to a spinner, and the spinner was rotated to form a transparent thin film by a spin coating method, and then dried by a heat treatment.

A high-refractive-index polymer solution was dropped thereon, and a high-refractive-index polymer layer was similarly formed by a spin coating method. Further, a solution of a low refractive index polymer was dropped thereon, and a three-layer film was formed in the same manner by a spin coating method.

In the case of a five-layer structure, the film formed above is taken in a temporary frame,
The temporary frame was inverted and attached to a spinner, and a solution of a high-refractive-index polymer and a low-refractive-index polymer was applied in the same manner as described above to form a film. The results are shown in Table 1.

From the above results, all of the examples obtained excellent results in both transmittance and film surface. On the other hand, in Comparative Examples 1 and 2, a flow was generated on the film surface because the rotation rise speed was higher than the formula [IV]. In Comparative Example 3, the minimum light transmittance was low because the molar ratio of vinylnaphthalene / styrene was small. In Comparative Example 4, an orange pill was generated on the film surface because the solvent of the high refractive index polymer had a low boiling point.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahide Tanaka 61-2, Waki, Waki-cho, Kuga-gun, Yamaguchi Prefecture Inside Mitsui Petrochemical Industry Co., Ltd. (56) References JP-A-61-209449 (JP, A JP-A-60-237450 (JP, A) JP-A-1-16873 (JP, A)

Claims (4)

(57) [Claims] 1. A three-layer structure comprising a low-refractive-index polymer / high-refractive-index polymer / substrate in which a high-refractive-index polymer is coated on one or both sides of a substrate made of a transparent thin film, and a low-refractive-index polymer is further coated thereon. Or a high light-transmitting dustproof film having a five-layer structure of low refractive index polymer / high refractive index polymer / substrate / high refractive index polymer / low refractive index polymer; (Wherein R ¹ is —CH ＝ CH ₂ or It is. And at least one naphthalene derivative monomer selected from (Wherein R ² is —CH ＝ CH ² , Or R ³ is H, an alkyl group having 1 to 10 carbon atoms, It is. A highly light-transmitting dustproof film characterized by using a 95/5 to 60/40 (molar ratio) copolymer with at least one benzene derivative monomer selected from the group consisting of: 2. The highly light-transmitting dustproof film according to claim 1, wherein the substrate is a cellulose derivative. 3. The low refractive index polymer has a general formula (Wherein, R ⁴ is H or —CH ₃ , and R ⁵ is a fluoroalkyl group optionally containing an ether oxygen atom therebetween.) A fluorine-containing poly (meta) containing at least one monomer selected from the group consisting of 3.) The highly light-transmitting dustproof film according to claim 1, wherein the film is acrylate. 4. A high refractive index polymer having a boiling point of 120 to 2
After supplying a solution dissolved in a solvent at 00 ° C. to form a film by a rotary film forming method, a solution of a low refractive index polymer is supplied thereon, and the formula (Wherein, M is the molecular weight of the high refractive index polymer). The method according to any one of claims (1) to (3), wherein the film is laminated by a rotational film forming method at the following rotational speed. The method for producing a highly light-transmitting dustproof film according to the above.