JPH01221702A - Production of pellicle film - Google Patents

Abstract

PURPOSE:To increase the adhesive power between a thin transparent film and antireflection layer by supplying a polymer soln. prepd. by dissolving specific fluorine-contained polyacrylate onto a thin cellulose deriv. film and forming the antireflection layer by a spin film forming method. CONSTITUTION:The polymer soln. prepd. by dissolving the fluorine-contained (meth)acrylate which contains the monomer selected from formula I and has >=50wt.% fluorine content in the polymer into the solvent which can dissolve said fluorine-contained (meth)acrylate and does not dissolve or swell the substrate-shaped cellulose deriv. and has the b.p. in a 40-220 deg.C range is supplied into the dried thin cellulose derive. film and the antireflection layer consisting of the fluorine polymer is formed by the spin film forming method. In formula, R<1> denotes H or methyl group; R<2> denotes a fluoroalkyl group which may con tain an ether-oxygen atom in-between. The inter-layer adhesive power between the cellulose derive. layer and the fluorine-contained poly(meth)acrylate polymer layer is thereby increased and the two layers are pulled and stripped without separating the film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a pellicle film having an antireflection layer used in a pellicle as a dustproof cover for a photomask or reticle.

[Conventional technology]

In the semiconductor exposure process, a method has been proposed for preventing the influence of dust on the exposure process and improving productivity by using a dustproof cover called a pellicle in combination with a photomask or reticle (Japanese Patent Publication No. 54 -28
No. 716). A pellicle has a structure in which a pellicle film is stretched on one side of a pellicle frame, and is used over a photomask or reticle.

Conventionally, a single-layer thin film of nitrocellulose has been mainly used as the pellicle membrane that makes up such a pellicle, but in order to improve throughput in the exposure process, an anti-reflection layer is provided on a transparent thin film of nitrocellulose. A pellicle membrane has been proposed (Japanese Patent Application Laid-Open No. 60-2374
No. 50, JP-A-61-53601 or JP-A-61
-209449).

Among these, JP-A No. 60-237450 describes the use of fluorine-based polymers or silicone-based polymers as antireflection layers, but the fluorine-based polymers shown are tetrafluoroethylene vinylidene fluorocarbons. Ride copolymer or tetrafluoroethylene vinylidene fluoride ° hexafluoropropylene copolymer. JP-A-61-53601 also indicates that fluorine-based polymers and silicone-based polymers can be used as antireflection layers, but the fluorine-based polymers specifically shown are tetrafluoroethylene, vinylidene, etc. It is a fluoride/hexafluoropropylene copolymer. Japanese Patent Publication No. 61-20944
No. 9 states that fluorine-based polymers containing polyfluoro(meth)acrylate can be used as antireflection M, but the specific explanation is similar to the above, such as tetrafluoroethylene vinylidene fluoride.
It is a hexafluoropropylene polymer.

[Problem to be solved by the invention]

However, such a conventional pellicle film with an antireflection layer is manufactured by a rotational film forming method by supplying each solution onto a substrate, but in addition to having low light transmittance, it is difficult to separate the transparent thin film and the antireflection layer. There was a problem that the adhesive force was weak. Therefore, when the pellicle film formed on the substrate is peeled off from the substrate, it is necessary to swell and peel it off in water, which may cause wrinkles in the pellicle film when drying, and also has poor productivity.

An object of the present invention is to produce a pellicle film that can prevent the generation of interference light by preventing reflection of light and has high light transmittance without swelling or peeling in water or causing wrinkles. The aim is to propose a method that can do this.

[Means to solve the problem]

That is, the present invention is the following method for manufacturing a pellicle membrane.

(1) A cellulose derivative solution is supplied onto the substrate, a cellulose derivative thin film is formed by a rotary film forming method, and after drying, the general formula % formula % (1) [where R1 is H or a methyl group, and R2 is between It is a fluoroalkyl group which may contain an ether oxygen atom. ] This fluorine-containing poly(meth)acrylate containing at least one monomer selected from the following and having a fluorine content of 50% by weight or more in the polymer
An antireflection type pellicle characterized in that a polymer solution dissolved in a solvent that can dissolve acrylate and does not dissolve or swell the cellulose derivative is supplied onto the cellulose derivative thin film, and an antireflection layer is formed by a rotational film forming method. Membrane manufacturing method.

(2) On the substrate, the general formula % formula % () [However, R1 is H or a methyl group, and R1 is a fluoroalkyl group which may contain an ether oxygen atom between them. ] A solution of fluorine-containing poly(meth)acrylate containing at least one monomer selected from the following and having a fluorine content of 50% by weight or more in the polymer is supplied, a thin film is formed by a rotary film forming method, and then dried. After that, a cellulose derivative solution is supplied onto this thin film, and a cellulose derivative thin film is formed by a rotary film forming method. After drying, the fluorine-containing poly(meth)acrylate is dissolved and the cellulose is further added onto this cellulose derivative thin film. A reflective film in which antireflection layers are formed on both sides, characterized in that a polymer solution in which the fluorine-containing poly(meth)acrylate is dissolved is supplied to a solvent that does not dissolve or swell the derivative, and a film is formed by a rotational film forming method. A method for manufacturing a protective pellicle membrane.

In the present invention, the cellulose derivative that forms the transparent thin film that is the main body of the pellicle membrane is 3, which is used for exposure.
Any material having a high average light transmittance at a wavelength of 50 to 450 nm may be used, but cellulose derivatives such as nitrocellulose, ethylcellulose, and cellulose propionate are preferred. Among these, nitrocellulose is preferred in terms of average light transmittance between 350 and 450 nm and film strength.

Nitrocellulose is 11-12.5%, especially 11.5-12.5%
Nitrification degree (N%) of 12.2%, and 150,000~
350,000, especially 170,000-320,000
Those having an average molecular weight (weight average, Mv) of are preferred.

Here, the average light transmittance is a value obtained by taking the same number of peaks and valleys of interference waves of light transmittance occurring between 350 and 450 nm and averaging them.

The thickness of the transparent thin film formed from cellulose derivatives is
It is selected to have high transmittance for the target wavelength between 350 and 450 nm, but to increase the transmittance for the currently used exposure wavelength of 436 nm + 405 nm + 365 nm, it is usually 2.85 μm or 436 nm.
0.865 μm is selected to increase the transmittance for m.

The antireflection layer formed on such a transparent thin film is made of a fluorine-containing polymer containing at least one monomer selected from the general formula (1) and having a fluorine content of 50% by weight or more. It is made of (meth)acrylate.

R2 in the general formula (1) has 2 to 1 carbon atoms;
4, a fluoroalkyl group which may contain an ether oxygen atom between them is preferable, and specifically, -CH, CF,
, -CH,C,F,, -CH2C,F7. -CH2
C4F.

-C82C,F, □, -CH2C,F engineerings * -C
H2Cs Ft□, -CH2C9F1. .

-CH2C,. F21. -CH, CH, CF3. -CI
l, CH2C, Fs.

-C)l, CI(2C,F7.-C)I, CH□C4F
---CHz CH2C5F.

-CH,CH,C,Fi,, -CH2CIlzC,F
,,, -CH,CH,C,F,,.

-CI, C1 (2C1, F, 1.-CHI□(CFz)
zl(,-Cut(Ck)J--CH,(CF2),)
l, -cu, (cFs), u, -C)1. (CF2
)□,)I.

-C1((CF,)2.-CH,CH2C4FCF,,
-CH, CF, CHF (CF2), H.

-CH, -CF (CF3)C)IFcF (CF,
)! .

-CH2CF (C2F, )CIl (CF, )2
．． -CH□'C, HF, □.

-CGHF, -C1, C engineering. HF, -Cl
, -C,F,H.

-(CH2), 0CF(CF,), -(Co,)L□
OCF (CF,)z.

-CH, (CF2), OCF, -CH2(CF,
), OC,F, .

-CH, (CF, ), QC, F,.

For example,

The fluorine-containing poly(meth)acrylate may be a homopolymer of one type of the above-mentioned heptamers, or a copolymer of two or more types.

In the case of a copolymer, a linear fluoroalkyl group that does not contain an ether oxygen atom, a linear fluoroalkyl group that contains an ether oxygen atom, or a branched fluoroalkyl group that may contain an ether oxygen atom; A combination of these is preferable because the light transmittance increases.

Further, the fluorine-containing poly(meth)acrylate has the above-mentioned general formula (
It may also be a copolymer of the hexamer I) and other monomers. Other monomers to be copolymerized with the monomer of general formula (1) are not particularly limited, but include those of the general formula % formula % () [However, R3 is H or a methyl group, and R4 is an alkyl group that may contain an ether oxygen. It is. ] At least one monomer selected from the following is preferred. The fluorine-containing poly(meth)acrylate made of such a copolymer has R
By appropriately changing the types of substituents 1 to R4, the copolymer composition, etc., a polymer having a desired fluorine content can be produced.

R4 in general formula [11] has 1 to 50 carbon atoms.
, preferably 4 to 24 alkyl groups, specifically -CH3, -C,H,, -C4H,, -CGH,
,.

-C, R17, -C, + (8,, -C engineering. H2□l -
czz)lzst-cm78351-C181(37
Examples include 1-C24H491-C34H69, which may contain ether oxygen.

Alkyl group-containing (meth) of general formula (II) combined with fluorine-containing (meth)acrylate monomer of general formula [I]
The mixture of other monomers such as acrylate is 70 mol%
Hereinafter, preferably 5 to 40 mol%.

The fluorine-containing poly(meth)acrylate must have a fluorine content of 50% by weight or more, and 50% by weight or more.
Preferably, it is 70% by weight. When the amount is within the above range, a layer that is transparent, has a high average light transmittance, and does not cause color unevenness or whitening due to glabellar disorder can be obtained.

If the fluorine content in the polymer is less than 50% by weight, it will be attacked during the formation of transparent thin films of cellulose derivatives, etc., resulting in uneven color, and the minimum light transmittance at wavelengths between 350 and 450 nm will be less than 90%. As the average light transmittance decreases, the undulation of the transmittance fluctuation due to interference light becomes sharper, and the wavelength dependence of the transmittance becomes stronger.

The above-mentioned fluorine-containing poly(meth)acrylate, which becomes the antireflection layer, is formed on one or both sides of a transparent thin film such as a cellulose derivative, and the film thickness is 1/4n (n) of the wavelength of the target light. is preferably a refractive index).

The method for manufacturing a pellicle film having an antireflection layer of the present invention includes:
This is done as in the case of a single-sided anti-reflection pellicle film.

That is, first, a cellulose derivative solution is supplied onto a smooth substrate such as glass, and a transparent thin film of the cellulose derivative is formed by a one-turn film forming method. A solution of the cellulose derivative dissolved in a solvent and purified by filtration or the like is used. As the solvent, ketones such as methyl ethyl ketone, methyl isobutyl ketone, methyl ethyl ketone, and acetone, lower fatty acid esters such as butyl acetate and isobutyl acetate, and mixed solvents of the above-mentioned ketones or esters with isopropyl alcohol and the like are used. The thickness of the transparent thin film formed can be changed as appropriate by changing the viscosity of the solution and the rotation speed of the substrate.

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

Next, the fluorine-containing poly(meth)acrylate polymer solution is supplied onto the dried cellulose derivative thin film, and an antireflection layer made of a fluoropolymer is formed by the rotary film forming method in the same manner as the cellulose derivative thin film. At this time, the solvent for dissolving the fluorine-containing poly(meth)acrylate is a solvent that can dissolve the fluorine-containing poly(meth)acrylate and does not dissolve or swell the cellulose derivative on the substrate, and has a boiling point of 40 to 220 °C, Preferably, the temperature range is from 60 to 150°C, and aromatic halogen compounds, fluoroalkylated alcohols, fluoroolefins (
For example, tetrafluoroethylene oligomers, hexafluoropropylene oligomers, etc.), fluorinated cyclic ether compounds, etc. are used. Specifically, H(CF2), CH, OH, CF, (CF,)2CH,
Oh.

F(CF2-CF2)20H2CH,OH,CF,CF
2CH20H.

Among these, meta-xylene hexafluoride, propatool pentafluoride, pencitrifluoride and the like are particularly preferred.

By using these specific solvents, a fluorine-containing poly(meth)acrylate polymer solution with good rotary film forming properties can be obtained, and when forming an antireflection layer made of fluorine-containing poly(meth)acrylate, .

It is possible to prevent the adverse effects of dissolving or swelling the cellulose derivative thin film serving as the base layer.

The thickness of the antireflection layer can be controlled by appropriately changing the solution viscosity, the rotation speed of the substrate, etc., similarly to the cellulose derivative thin film.

On the other hand, in the case of a double-sided anti-reflection pellicle film.

A fluorine-containing poly(meth)acrylate polymer solution (however, the solvent is not limited to the above-mentioned solvents, as long as it can dissolve the same polymer) is supplied onto a smooth substrate such as glass, and a rotating A thin film of fluorine-containing poly(meth)acrylate polymer is formed by a membrane method and dried by means such as hot air or infrared lamp irradiation to remove residual solvent. After that, the same operation as above was performed on this thin film to form a double-sided anti-reflection pellicle film with a three-layer structure of fluorine-containing poly(meth)acrylate polymer/cellulose derivative/fluorine-containing poly(meth)acrylate polymer. can be manufactured.

In this manner, the single-sided or double-sided antireflection pellicle film formed on the substrate is peeled off from the substrate for use as a pellicle. In this case, for example, cellophane tape or a frame-shaped jig coated with adhesive is applied to the outermost layer of a laminated film formed on a substrate, that is, a thin film of fluorine-containing poly(meth)acrylate polymer that is in contact with the outside air. However, by lifting cellophane tape or a frame-shaped jig from one end by hand or mechanical means, it can be directly peeled off from the substrate. At this time, since the interlayer adhesive force between the cellulose derivative layer and the fluorine-containing poly(meth)acrylate polymer layer is strong, the film is peeled off without separation, and a pellicle film having an antireflection layer is obtained.

The pellicle membrane thus manufactured is attached to a pellicle to form a pellicle.

〔Effect of the invention〕

According to the manufacturing method of the present invention, since the adhesive force between the transparent thin film and the antireflection layer is strong, even if the transparent thin film and the antireflection layer are peeled off directly from the film forming substrate, the layers can be peeled off in a laminated state.

A pellicle film having an antireflection film can be manufactured by a single rotation film forming method without swelling and peeling in water or causing wrinkles.

In addition, the pellicle film having the antireflection layer manufactured according to the present invention has an improved minimum light transmittance in the wavelength range of 350 to 450 nn+, and the variation in light transmittance due to interference of reflected light is reduced, so the average light transmittance is improved. This also improves the throughput in the exposure process.

〔Example〕

Examples of the present invention will be described below.

Example 1 Nitrocellulose was dissolved in methyl isobutyl ketone to form a 6% by weight solution. On the other hand, a copolymer of 33 mol% perfluorooctylethyl acrylate and 67 mol% trifluoroethyl acrylate [fluorine content 52.
8% by weight] was dissolved in meta-xylene hexafluoride to make a 1.0% by weight solution.

By a spin coating method, the above nitrocellulose solution is dropped onto a quartz substrate to form a nitrocellulose thin film, and dried.
The above fluorine-containing polymer solution was dropped onto this, and
It was dried by spinning for 60 seconds in a pra. The pellicle film thus obtained is peeled off from the substrate and framed in a predetermined frame.
A pellicle having an antireflection layer on one side was obtained.

The above pellicle is a spectrophotometer (UV-24 manufactured by Shimadzu Corporation).
According to the spectral characteristics measurement by 0), the minimum light transmittance in the range from 350 to 450 nm is 90.5%, and the average transmittance is 94.8.
It was ~95%. On the other hand, the spectral characteristics of a pellicle membrane made solely of nitrocellulose (Comparative Example 1) had a minimum light transmittance of 84% and an average transmittance of 92%.

Examples 2 to 8 Table 1 shows the results of the same tests as in Example 1, with different types of fluorine-containing polymers.

Example 9 The same nitrocellulose solution and fluorine-containing polymer solution as in Example 1 were prepared.

Using a quartz substrate, a fluorine-containing polymer was first dropped onto the substrate by a spin coating method, rotated at 500 rpm for 60 seconds, and then dried. A nitrocellulose solution was dropped onto this to form a thin film, which was then dried.Furthermore, a fluorine-containing polymer was dropped onto this, and the film was rotated at 500 rpm for 60 seconds, followed by drying. This pellicle film having single-layer antireflection layers on both sides could be peeled off smoothly from the substrate. As for the spectral characteristics of this pellicle film, the minimum light transmittance at 350 to 450 nm was 95%, and the average transmittance was 97 to 98%.

Agent: Patent attorney Sei Yanagi Hara

Claims (2)

[Claims] (1) After supplying a cellulose derivative solution onto the substrate and forming a cellulose derivative thin film by the rotational film forming method and drying it, a general formula ▲ Numerical formula, chemical formula, table, etc. ▼... [I] [However, R ^1 is H or a methyl group, and R^2 is a fluoroalkyl group which may contain an ether oxygen atom between them. ] This fluorine-containing poly(meth)acrylate containing at least one monomer selected from the following and having a fluorine content of 50% by weight or more in the polymer
An antireflection type pellicle characterized in that a polymer solution dissolved in a solvent that can dissolve acrylate and does not dissolve or swell the cellulose derivative is supplied onto the cellulose derivative thin film, and an antireflection layer is formed by a rotational film forming method. Membrane manufacturing method. (2) There is a general formula▲mathematical formula, chemical formula, table, etc. on the substrate▼... [I] [However, R^1 is H or a methyl group, and R^2 even if it contains an ether oxygen atom in between. It is a good fluoroalkyl group. ] A solution of fluorine-containing poly(meth)acrylate containing at least one monomer selected from the following and having a fluorine content of 50% by weight or more in the polymer was supplied, a thin film was formed by a rotary film forming method, and then dried. Thereafter, a cellulose derivative solution is supplied onto this thin film to form a cellulose derivative thin film by a rotary film forming method. After drying, the fluorine-containing poly(meth)acrylate can be dissolved and the cellulose derivative can be dissolved on this cellulose derivative thin film. Alternatively, an antireflection type pellicle film having an antireflection layer formed on both sides is formed by supplying a polymer solution in which the fluorine-containing poly(meth)acrylate is dissolved in a non-swelling solvent and using a rotational film forming method. manufacturing method.