JPH0412355A - High pay transmittable dustproof film, production thereof and dustproof body - Google Patents

Abstract

PURPOSE:To obviate the generation of photodecomposition in spite of irradiation with short-wavelength light over a long period of time and to obtain a high ray transmissivity by using a perfluoro-amorphous fluorinated resin as a film forming component. CONSTITUTION:The amorphous fluorsinated resin in which the hydrogen atoms are all substd. with fluorine resins is usable as the perfluoro-amorphous fluorinated resin forming a perfluoro-amorphous fluorinated resin film 6. The amorphous fluororesins in which at least one repeating units from a cyclic structure are more preferable usable. The repeating units thereof may contain oxygen atoms or sulfur atoms, etc., in addition to the carbon atoms and fluorine atoms. The high ray transmittable dustproof film which obviates the generation of the photodecompositin in spite of the irradiation with the light of the short wavelength, such as not only (g) and (i) rays but excimer laser as well, and has the high light transmittance is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is aimed at preventing dust from being removed from a photomask, reticle, etc. (hereinafter simply referred to as a mask, etc.) used in a photolithography process in the manufacturing process of semiconductor devices such as ICs and LSIs. The present invention relates to a dustproof film used to prevent foreign matter from adhering to the present invention, a method for manufacturing the same, and a dustproof body.

[Conventional technology]

In the photolithography process, a mask is used to form a circuit pattern on the surface of a glass plate using a vapor-deposited film such as chromium.
Work is underway to transfer the circuit pattern onto a silicon wafer coated with resist. In this process, if exposure is performed with foreign matter such as dust attached to a circuit pattern on a mask or the like, the foreign matter will also be transferred onto the wafer, resulting in a defective product. In particular, when the exposure is performed using a stepper, there is a high possibility that all the chips formed on the wafer will be defective, and adhesion of foreign matter to circuit patterns such as masks is a big problem. In order to solve this problem, in recent years, a dustproof body (pellicle) has been used in which a transparent light-transmitting dustproof film (pellicle film) is arranged at appropriate intervals on one or both sides of a mask substrate such as a mask.

This dustproof body is generally made of an aluminum holding frame with a transparent, light-transmitting dustproof film made of organic material such as nitrocellulose stretched on one side of the frame, and a double-sided adhesive tape is attached to the other side of the frame to make masks, etc. It is designed to be mounted on a mask substrate. According to this, intrusion of foreign matter from the outside can be prevented, and even if foreign matter adheres to the film, it will not be transferred onto the wafer, improving the yield in manufacturing semiconductor devices.

However, as the degree of integration of semiconductor devices improves, the light beam used for exposure has changed from g-line (436 nm) to i-line (365 nm), and even excimer laser (KrF: 248 nm, ArF).
: 193 nm).
Conventional light-transmitting dust-proof films made of organic substances such as nitrocellulose have the problem of photodegradation and impractical use.

In order to solve these problems, light-transmitting dustproof films made of inorganic substances such as synthetic quartz, quartz, and fluorite have also been proposed (Japanese Patent Laid-Open Nos. 62-288842 and 63-6553). However, when forming a thin film from the above-mentioned inorganic material, there is a problem that it is difficult to form a single film compared to when forming a thin film from an organic material.

[Problem to be solved by the invention]

The purpose of the present invention is to solve the above problems,
In addition to the conventional G-line and I-line, it does not cause photodecomposition even when irradiated with short wavelength light such as excimer laser for a long period of time, and has a high light transmittance. It is to provide.

Another object of the present invention is to propose a method for easily producing a high light transmittance dustproof film having the above-mentioned excellent properties in a short time.

Furthermore, another object of the present invention is to provide a dustproof body made of a highly light-transparent dustproof film having the above-mentioned excellent properties.

[Means to solve the problem]

The present invention provides the following high light transmittance dustproof film, method for producing the same, and dustproof body.

(1) High light transmittance dustproof film made of perfluoro amorphous fluororesin.

(2) The high light transmittance dustproof film according to the above (1), which transmits 85% or more of light of 190 to 500 nm in average light transmittance.

(3) The high light transmittance dustproof film according to (1) above, having a film thickness of 0.2 to 10 μm.

(4) A method for forming a film by supplying a solution of a film-forming component onto a substrate and rotating the substrate, characterized in that a perfluoro amorphous fluororesin is used as the film-forming component ( 1) The method for producing the high light transmittance dustproof film described above.

(5) In the method of forming a film by immersing a substrate in a solution of a film-forming component and then pulling it up, the method described in (1) above, characterized in that a perfluoro amorphous fluororesin is used as the film-forming component. A method for producing a high light transmittance dustproof film.

(6) A method of forming a film by spreading a solution of a film-forming component on a liquid surface, characterized in that a perfluoro amorphous fluororesin is used as the film-forming component (1) above.
The method for producing the highly light-transparent dustproof film described above.

(7) A dustproof body comprising the highly light-transparent dustproof film according to any one of (1) to 3) above and a holding frame.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A highly light-transparent dust-proof film of the present invention and a dust-proof body in which this dust-proof film is stretched over a holding frame will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an example of the dustproof body of the present invention. In the figure, reference numeral 1 denotes a dustproof body, and a highly light-transparent dustproof film 3 is stretched on one side of a holding frame 2, and the opposite side is attached to a mask substrate 5 of a mask or the like with double-sided adhesive tape 4 or the like. It has become so. The dustproof body 1 having such a configuration is
This prevents foreign matter such as dust from adhering to the mask substrate 5 during the manufacturing process of semiconductor elements.

FIG. 2 is a cross-sectional view of a part of the high light transmittance dustproof film 3.

This high light transmittance dustproof film 3 is composed of a single perfluoro amorphous fluororesin film 6, but in some cases, an antireflection layer may be laminated on the perfluoro amorphous fluororesin film 6. .

As the perfluoro amorphous fluororesin forming the perfluoro amorphous fluororesin film 6, an amorphous fluororesin in which all hydrogen atoms are replaced with fluorine atoms can be used.
Those in which at least one type of repeating unit forms a cyclic structure can be preferably used. These repeating units may contain oxygen atoms, sulfur atoms, etc. in addition to carbon atoms and fluorine atoms.

Examples of such perfluoro amorphous fluororesin include JP-A-1-131214 and JP-A-1-13121.
No. 5, EP 303298A2, EP 303292A
Examples include polymers or copolymers having one or more types of repeating units selected from the group consisting of repeating units represented by the following repeating units (1) to [■], as disclosed in 2. .

1'3 Sil''3 In addition to the repeating units represented by the above-mentioned repeating units (1) to V), the perfluoro amorphous fluororesin also includes a repeating unit represented by the following repeating unit (VI). Copolymers can also be preferably used (for example, the copolymers disclosed in Japanese Patent Publication No. 18964/1983).

-(-CF.-CFA← ・・・[V
I] (wherein A is a fluorine atom, -0CF, CF2CF
, or -OCF2CF (CF3)OCF, CF2
Indicates SO2F. ) Specific examples of perfluoro amorphous fluororesin include perfluoro 2,2-dimethyl-
Copolymer of 1,3-dioxole and tetrafluoroethylene, polymer consisting of repeating unit (1), polymer consisting of repeating unit (II), polymer consisting of repeating unit (III), repeating unit (IV) ), polymers consisting of repeating units (V), repeating units (1) and (II
), a copolymer consisting of repeating units (Il and (m)), a copolymer consisting of repeating units [1] and [IV], a copolymer consisting of repeating units [1] and [11], and ( A copolymer consisting of the repeating unit (1) and [■] (where A is a fluorine atom), a copolymer consisting of the repeating unit (I
A copolymer consisting of I) and (m), a copolymer consisting of repeating units (n) and (IV), a copolymer consisting of repeating units (11) and [
A copolymer consisting of [■] (where A is a fluorine atom), a repeating unit (n), a copolymer consisting of (IV), and [■] (where A is a fluorine atom), a repeating unit (If) and (I
V) and [VI] (where A is 10 CF. CF (CF
3) Copolymer consisting of OCF, CF2So, F), repeating unit (I) and [■] (where A is one OCF,
C.F. CF3), and these polymers or copolymers contain CF2=CF, which is a raw material for production.
O (CF.), CF=CF. (Here, n represents 1 or 2) etc. can be exemplified by copolymerization of derivatives derived from the above.

As a perfluoro amorphous fluororesin, the repeating unit [
In addition to 1) to VI), copolymerizable monomers with other copolymerizable monomers can also be used as long as the purpose of the present invention is not impaired.

Such perfluoro amorphous fluororesin is, for example, C
F2=CFO (CF2), CF=CF. (Here n
represents 1 or 2), perfluoro 2,2-dimethyl-1,3-dioxole, CF2=CFA (where A
(indicates the same thing as above), etc. can be produced by radical polymerization.

In addition, examples of the perfluoro amorphous fluororesin include CYTOP (manufactured by Asahi Glass Co., Ltd., trademark), Teflon A
F1600 (TEFLON AF1600, manufactured by DuPont, trademark), Teflon AF2400 (TEFLON
Commercially available products such as AF2400 (manufactured by DuPont, trademark) can also be used.

The above-mentioned perfluoro amorphous fluororesins include perfluorotributylamine (CT-3OLV, manufactured by Asahi Glass Co., Ltd., trademark), perfluoro(2-butyltetrahydrofuran) (Florinart FC75, manufactured by Sumitomo 3M Co., Ltd.), Trademark), trichlorotrifluoroethane, perfluorobenzene, and other solvents, it can be easily formed into a film using almost the same process as conventional organic films.

Thin films made of perfluoro amorphous fluororesin 1 have good light transmittance not only for visible light but also for short wavelengths such as excimer lasers, and have almost no absorption, so they are resistant to photodegradation even when exposed to long-term light irradiation. It has high light transmittance.

The thickness of the perfluoro amorphous fluororesin film 6 constituting the high light transmittance dustproof film 3 is preferably 0.2 to 10 μm.
m, and the light transmittance of the high light transmittance dustproof film 3 is 19
It transmits 85% or more of light with an average light transmittance of 0 to 500 nm. Here, the average light transmittance is 19
This is the average value of the same number of peaks and valleys of interference waves of light transmittance occurring between 0 and 500 nm.

By setting the thickness of the perfluoro amorphous fluororesin film 6 to 0.2 to 10 tones, it is possible to obtain a dustproof film that is strong enough to be easily handled and has small aberrations during exposure.

The thickness of the perfluoro amorphous fluororesin film 6 is selected so that the transmittance is high for the wavelength used for exposure.

As shown in FIG. 2(a), when the high light transmittance dustproof film 3 is composed of a single perfluoro amorphous fluororesin film 6, the thickness of the perfluoro amorphous fluororesin film 6 is d□, When the refractive index is n□ and the wavelength is λ, reflection is prevented and the transmittance is the highest when m is an integer of 1 or more. For example, n
In the case of 1=1.3, in order to increase the transmittance of the g-line (436 nm), the film thickness d1 should be set to 1.84 μm, for example, and Kr
To increase the transmittance of F excimer laser (248 nm), the film thickness d1 is set to, for example, 1.05 μm.

Although an anti-reflection film is not necessarily required for the high light transmittance dustproof film 3 of the present invention, it is possible to prevent the transmittance from decreasing because the perfluoro amorphous fluororesin film 6 of the desired thickness cannot be obtained. An antireflection layer 7 may be laminated on the perfluoro amorphous fluororesin film 6 in order to prevent the change in transmittance due to changes in wavelength.

The perfluoro amorphous fluororesin film 6 is made by: (1) supplying a perfluoro amorphous fluororesin solution onto a clean and smooth substrate;
A method of forming a film by rotating a spinner and using a rotary film forming method. ■ After immersing a substrate with a clean and smooth surface such as glass in a perfluoro amorphous fluororesin solution, the substrate is pulled up to form a thin film. It can be manufactured by a method of forming a film by a dipping method.

The concentration of perfluoro amorphous fluororesin solution is usually 0.5
-15% by weight, preferably 1-9% by weight.

Substrates used in the above method include, for example, inorganic single crystal substrates such as silicon wafers and sapphire wafers; metal substrates such as aluminum and nickel; ceramic substrates such as aluminum oxide, magnesium oxide, quartz glass, and soda lime glass; polycarbonate and acrylic resin. Organic substrates such as; substrates on which metal thin films, ceramic thin films, organic thin films are formed on these inorganic single crystal substrates, metal substrates, ceramic substrates, organic substrates by CVD, spin coating, etc.; stretched on metal frames, etc.; Examples include metal films such as aluminum foil and organic films such as nitrocellulose films.

The thin film obtained by the above method is dried by means such as hot air or infrared irradiation, and then the thin film is separated from the substrate to obtain a single film made of perfluoro amorphous fluororesin. Methods for separating the thin film from the substrate include, for example, immersion in water, physical peeling, etching of the substrate with an etching solution, dissolution of the substrate with a solvent, etc., and decomposition of the substrate by heat treatment. Note that when a single film is obtained by immersion in water, peeling can be made easier by applying vibration with an ultrasonic cleaner or the like or using hot water.

Furthermore, in addition to methods ① and ② above, as a method for obtaining the perfluoro amorphous fluororesin film 6, ② a perfluoro amorphous fluororesin solution is placed on the surface of a liquid having a higher specific gravity and surface tension than this solution. One method is to develop a thin film. Examples of such liquids include acetylene tetrabromide (CI-IBr2C)IBrz). The thin film thus obtained is scooped up from above the liquid surface to form a single film.

If necessary, an antireflection layer 7 is laminated on the perfluoro amorphous fluororesin film 6 obtained in this manner, and the film is stretched over the holding frame 2 to complete the dustproof body 1.

[For production]

A dust-proof body 1 having a highly light-transmitting dust-proof film 3 stretched over a holding frame 2 is attached to a mask substrate 5 such as a mask using double-sided adhesive tape 4 or the like to prevent the adhesion of foreign matter such as dust during exposure. During exposure, since the perfluoro amorphous fluororesin film 6 is not decomposed by short wavelength light such as excimer laser, exposure can be performed stably, the transmittance is high, and the exposure efficiency is high.

〔Effect of the invention〕

According to the present invention, perfluoro amorphous fluororesin is used as the material for forming the dustproof film, so it can be irradiated with short wavelength light such as excimer laser for a long period of time, as well as G-line and I-line. Also, a highly light-transmitting dustproof film that does not cause photodecomposition and has high transmittance can be obtained.

Further, according to the present invention, the above-mentioned high light transmittance dustproof film can be easily produced in a short time.

Furthermore, according to the present invention, a dustproof body made of a highly light-transparent dustproof film having the above-mentioned excellent properties can be obtained.

〔Example〕

Example 1 CYTOP (manufactured by M Glass Co., Ltd., prepared at 5.0 t%)
CT-5OLV (manufactured by 'M Glass Co., Ltd., trademark)
The solution was dropped onto a 70 mm x 70 mm glass substrate, and a film was formed by a rotary film forming method under the conditions of 500 rpm and 20 seconds. This film was heated from room temperature at a rate of about 0.degree. C./min, dried at about 180.degree. C. for 1 hour, allowed to cool, and then immersed in distilled water to be peeled off from the glass substrate to obtain a single film. The transparent thin film thus obtained has a refractive index of approximately 1.3, a film thickness of approximately 2.0/a, and a light transmittance of approximately 9 at 248 nm.
It was 6%.

Example 2 5.42 g of CF2=CFOCF2CF, CF=CF
2 and 10 mg of (C3F7C(”
0)O)2 was placed in a pressure-resistant glass ampoule with an internal volume of 50mM. After repeating freezing and degassing twice, polymerization was carried out at 25° C. for 48 hours. The pressure during the polymerization reaction was below atmospheric pressure. As a result, 2.22 g of polymer was obtained.

The glass transition point of this polymer was 108°C.

In addition, when the infrared absorption spectrum of this polymer was measured, it was found that the infrared absorption spectrum of this polymer was 1790 cm
There was no absorption near -1. Furthermore, when this polymer was dissolved in perfluorobenzene and an "F NMR spectrum was measured, a spectrum showing the following repeating structure was obtained.

4. 70 mm of perfluorotributylamine ((C4F9)3N) solution of the above polymer prepared to 5 wt%
Dropped onto a 70 mm x glass substrate, 500 rpm,
A film was formed by a rotary film forming method under conditions of 20 seconds. The temperature of this film was raised from room temperature at a rate of approximately ℃/min, and the temperature was increased to 180℃ for 1 hour.
After drying for a period of time and allowing to cool, it was immersed in distilled water and peeled off from the glass substrate to form a single film. The transparent thin film thus obtained has a refractive index of about 1.3, a film thickness of about 1.8I1m,
The light transmittance at 248° was about 96%.

Example 3 TEFLON AF (Fluorinated), an amorphous fluoropolymer prepared with 4.0%
(ethylenic-cyclo oxyaliph
atic 5ubstituted ethyleni
c) A solution of Fluorinert FC75 (manufactured by Jujutsu 3M Co., Ltd., trademark) of copolymer, DuPont Co., Ltd., was dropped onto a 70 mm x 70 mm glass substrate, and 1
A film was formed by a rotary film forming method under the conditions of 1000 rpm and 20 seconds. This film was heated from room temperature at a rate of about 0.degree. C./min, dried at about 150.degree. C. for 1 hour, allowed to cool, and then immersed in distilled water to be peeled off from the glass substrate to obtain a single film. The transparent thin film thus obtained has a refractive index of approximately 1.3 and a film thickness of approximately 1.3 mm. OIIm, the light transmittance at 248 nm was about 97%.

Example 4 The Fluorinert FC75 solution of the copolymer of perfluoro 2,2-dimethyl 1,3-dioxole and tetrafluoroethylene prepared to 3.1 ht% was mixed with 70 mm
Dropped onto a 70am glass substrate, 11000rp,
A film was formed by a rotary film forming method under conditions of 20 seconds. This film was heated from room temperature at a rate of about 0.degree. C./min, dried at about 150.degree. C. for 1 hour, allowed to cool, and then immersed in distilled water to be peeled off from the glass substrate to obtain a single film. The transparent thin film thus obtained has a refractive index of approximately 1.3 and a film thickness of approximately 1.3 mm. ll1
The light transmittance at 248 nm was about 97%.

[Brief explanation of drawings]

Figure 1 is a sectional view showing an example of the dustproof body of the present invention, Figure 2-
Axis →〒→+ is a cross-sectional view of a part of the high light transmittance dustproof film. In each figure, the same reference numerals indicate the same or equivalent parts, 1 is a dustproof body, 2 is a holding frame, 3 is a highly light-transparent dustproof film, 4 is a double-sided adhesive tape, 5 is a mask substrate, and 6 is a perfluoro amorphous crystal. This shows a quality fluororesin membrane. Agent Patent Attorney Sei Yanagihara

Claims (7)

[Claims] (1) High light transmittance dustproof film made of perfluoro amorphous fluororesin. (2) The high light transmittance dustproof film according to claim (1), which transmits 85% or more of light with an average light transmittance of 190 to 500 nm. (3) Claim (1) wherein the film thickness is 0.2 to 10 μm.
High light transmittance dustproof membrane as described. (4) A method for forming a film by supplying a solution of a film-forming component onto a substrate and rotating the substrate, characterized in that a perfluoro amorphous fluororesin is used as the film-forming component. (1) A method for producing a high light transmittance dustproof film. (5) In the method of forming a film by immersing a substrate in a solution of a film-forming component and then pulling it up, claim (1) characterized in that a perfluoro amorphous fluororesin is used as the film-forming component. The method for producing the highly light-transparent dustproof film described above. (6) A method for forming a film by spreading a solution of a film-forming component on a liquid surface, characterized in that a perfluoro amorphous fluororesin is used as the film-forming component.
) A method for producing a highly light-transparent dustproof film. (7) A dustproof body comprising the highly light-transparent dustproof film according to any one of claims (1) to (3) and a holding frame.