JPH07271016A - Lithography pellicle - Google Patents

Abstract

(57) [Summary] (Modified) [Objective] The present invention is an amorphous structure in which the pressure resistance against air blow or the like is remarkably improved as compared with the conventionally known pellicle film composed of a single layer of an amorphous fluoropolymer. An object of the present invention is to provide a pellicle for lithography, which is made of a high-quality fluoropolymer. The pellicle for lithography of the present invention is characterized in that the pellicle film is composed of a multilayer film of at least two kinds of amorphous fluoropolymers, and has a tensile yield strength of 30 MPa or more. An amorphous fluoropolymer film with an initial tensile modulus of less than 1.4 GPa and an initial tensile modulus of less than 30 MPa
It is a multi-layer film of at least two layers, which is formed by alternately superimposing an amorphous fluorine-based polymer film of 1.4 GPa or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used as a dust guard when manufacturing a pellicle for lithography, particularly a semiconductor device such as LSI or VLSI, or a liquid crystal display panel.
The present invention relates to an antistatic pellicle for lithography in an exposure system using light of substantially 500 nm or less.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices such as LSI and VLSI, or liquid crystal display panels, a semiconductor wafer or a liquid crystal original plate is irradiated with light for patterning. If there is, the dust absorbs the light or bends the light, so the transferred pattern may be deformed, the edges may be rough, and the white background may become black and stain, There is a problem in that the quality, appearance, etc. are impaired, and the performance and manufacturing yield of semiconductor devices, liquid crystal display panels, etc. are reduced. For this reason, these operations are usually performed in a clean room, but it is difficult to always keep the exposure master clean in this clean room.Therefore, the exposure master light often passes through the surface of the exposure master for exposure to prevent dust. A method of attaching a pellicle to be used is used.

In this case, since dust does not directly adhere to the surface of the exposure original plate but adheres to the pellicle, if the focus is aligned with the pattern of the exposure original plate during lithography,
Dust on the pellicle is irrelevant to transfer, but this pellicle film is nitrocellulose, which allows light to pass through well.
Aluminum, a transparent film made of cellulose acetate, etc.
It is bonded to the top of a pellicle frame made of stainless steel, polyethylene, or the like. However, as the pattern integration has progressed in recent years, the wavelength of the exposure light source has been shortened, and the light resistance of the pellicle film has come to be a problem accordingly. It has been proposed to use a fluorinated polymer (see JP-A-3-67262).

[0004]

However, this amorphous fluorine-based polymer has a drawback that it is weak in strength as compared with conventionally known cellulose-based polymers, and therefore, when foreign matter adheres to the pellicle film during use of the pellicle, When air blowing, which is an effective means for removing the above, is carried out under blowing conditions equivalent to those of the cellulosic polymer, the film often stretches and wrinkles or breaks. Since this air blowing step is an essential step for using the pellicle, this step cannot be eliminated, and this amorphous fluoropolymer should have a film strength that can withstand this step. It has been demanded.

[0005]

The present invention relates to a pellicle for lithography composed of an amorphous fluorine-based polymer, which solves the above disadvantages and problems, and it is a pellicle film containing at least two or more kinds of amorphous pellicle films. It is characterized by comprising a multilayer film of a porous fluoropolymer.

That is, the present inventors have conducted various studies on methods for improving the strength of a pellicle film made of an amorphous fluorine-based polymer. As a result, the pellicle film has two or more kinds of amorphous polymers of different types. It has been found that the pressure resistance against air blow is remarkably improved even if the film has the same thickness. Therefore, according to this, it is possible that the film is stretched or torn even if a normal air blow is performed on it. The present invention was completed by researching a specific combination of the plurality of amorphous fluorine-based polymers and the like.

[0007]

The present invention relates to a pellicle for lithography, which is characterized in that the pellicle film is composed of a multilayer film of at least two kinds of amorphous fluorine-containing polymers. Even if the thickness is the same as the thickness of a pellicle film made of a conventional single amorphous fluorine-based polymer, the pressure resistance against air blowing is significantly improved, and stretching and tearing occur with ordinary air blowing. No, it has the advantage of becoming stronger.

The present invention is supposed to consist of an amorphous fluorine-based polymer, and this amorphous fluorine-based polymer may be a known one, and therefore, this is a fluorine-containing polymer having tetrafluoroethylene and a cyclic perfluoroether group. It may be obtained by copolymerization with a system monomer, which has a formula sold under the trade name of Teflon AF [trade name of DuPont, USA].

[Chemical 1] (M and n are positive integers) or a formula sold under the trade name of CYTOP [trade name of Asahi Glass Co., Ltd.] consisting of a polymer of perfluorobutenyl vinyl ether.

[Chemical 2] Examples are shown by (n is a positive integer).

The pellicle film is produced from the amorphous fluorine-containing polymer by using the compound in a fluorine-containing solvent such as perfluoro (2-butyltetrahydrofuran) or perfluoro (2-propyltetrahydropyran). The film may be formed by a solution caster method using a spin coater or a knife coater after it is dissolved in a concentration of 10%. The pellicle for lithography of the present invention is a multilayer of two or more kinds of amorphous fluoropolymers as described above. Since it is required to form a film, this production requires repeated film formation using different types of amorphous fluoropolymers.

However, the pellicle film made of this amorphous fluorine-based polymer usually has a thickness of 0.8 to 0.8.
When the film has a thickness of 3 μm, it has the same initial tensile elastic modulus as that of the cellulosic pellicle film, but the tensile yield strength is inferior to that of the cellulosic pellicle film, and elongation occurs when air blowing is performed. Therefore, this can be achieved by increasing the thickness of the film, but in this case, there is a problem that the transmittance of light rays is lowered. Therefore, according to the present invention, when the pellicle film is a multilayer film of two or more kinds of amorphous fluoropolymers, the tensile yield strength of the pellicle film is improved, so that the pellicle film may be stretched or torn even by air blow. Because there is no
The thickness of this product can be 0.8 to 3 μm, which is the same as that of the conventional product, and the transmittance of light rays does not decrease.

In the pellicle for lithography of the present invention, the pellicle film is formed as a multi-layer film of two or more kinds of amorphous fluoropolymers, which is improved in terms of strength. Tensile yield strength
Amorphous fluoropolymer film (A film) with an initial tensile modulus of 1.4 GPa or more at less than 30 MPa and a tensile yield strength of 30
A double film composed of an amorphous fluoropolymer film (B film) having an initial tensile elastic modulus of less than 1.4 GPa at MPa or more is preferably used, and when this is used as a pellicle film,
The pressure resistance against air blow of the film is remarkably improved as compared with the pellicle film composed of only the A film and the B film having the same thickness.

Although only the A film + B film is exemplified in this structure, it is assumed that this is composed of three layers of A film + B film + A film or B film + A film + B film, and further, four layers. Good. However, the thickness of the pellicle film is required to be a predetermined thickness in consideration of the light transmittance.

[0013]

EXAMPLES Examples and comparative examples of the present invention will be given below.
The tensile yield strength and initial tensile modulus in the examples are AST.
The values measured according to the test method of MD638 are shown.

Example: Tensile yield strength is 27.0 MPa and initial tensile modulus is 1.55 GP.
Teflon AF1600, a copolymer of tetrafluoroethylene and perfluoro (2,2-dimethyl-1,3-dioxole), which is a, is a solvent, Fluorinert FC-75 [Sumitomo 3M ( stock)
[Product name] to prepare a solution with a concentration of 2%, and form a transparent film with a thickness of 0.42 μm on the surface-polished quartz substrate surface with a diameter of 200 mm and a thickness of 3 mm using a spin coater. And dried at 180 ° C. for 15 minutes.

Then, a polymer of Cytotop CTXS type perfluorobutenyl vinyl ether having a tensile yield strength of 38.2 MPa and an initial tensile modulus of 1.18 GPa [trade name of Asahi Glass Co., Ltd.] is used as a solvent.・ Prepare a solution with a concentration of 2% by dissolving it in CTSolv 180 [trade name of Asahi Glass Co., Ltd.], and use a spin coater to form a film thickness of 0.42 μm on the above spin-coated film. When a pellicle film having a thickness of 0.84 μm was formed by forming the film as described above and drying at 180 ° C. for 15 minutes, the light transmittance of this was 99.5%.

Next, an air gun having a nozzle outlet of 1 mm in diameter was used for this pellicle film, the distance from the tip of the nozzle to the film was 10 mm, the blowing time was 10 seconds, and the gas pressure was 0.5 k.
When air blown under the condition of 2.0kgf to 4.0kgf in gf increments, the results shown in Table 1 below are obtained, and this has strong pressure resistance against air blow. confirmed.

Comparative Example 1 Tensile yield strength is 38.2 MPa and initial tensile modulus is 1.18 GP.
The perfluorobutenyl vinyl ether polymer, Cytop CTXS type (a), is used as a solvent and CT.
Dissolve in Solv 180 (above) to prepare a 5% solution,
This solution was used to form a transparent film with a film thickness of 0.84 μm on a quartz substrate with a diameter of 200 mm and a thickness of 3 mm, which had been surface-polished, and was dried at 180 ° C for 15 minutes. The light transmittance was 99.5%. Since the pellicle film was obtained, the pellicle film was air-blown under the same conditions as in Example 1, and the results were obtained as shown in Table 1 below.
The film of this product stretched with an air blow of 3.0 kgf.

Comparative Example 2 Tensile yield strength is 27.0 MPa and initial tensile modulus is 1.55 GP.
a, a copolymer of tetrafluoroethylene and perfluoro (2,2-dimethyl-1,3-dioxole), Teflon AF1600 (described above), is dissolved in its solvent, Fluorinert FC-75 (described above). Prepare a 3% concentration solution, and use a spin coater to form a transparent film with a film thickness of 0.84 μm on a quartz substrate with a surface of 200 mm and a thickness of 3 mm. When dried, a pellicle film having a light transmittance of 99.5% was obtained. When this pellicle film was air blown under the same conditions as in Example 1, the results shown in Table 1 below were obtained. The film was torn by an air blow of 2.5 kgf.

[0019]

[Table 1]

[0020]

As described above, the present invention relates to a pellicle for lithography, which is characterized in that the pellicle film is composed of a multilayer film of at least two kinds of amorphous fluoropolymers. However, this one has improved film strength compared to the pellicle film made of a single layer of amorphous fluorine-based polymer, and the pressure resistance against air blow is remarkably improved. It is not necessary to make the film thicker, and therefore, the light transmittance is not reduced, and the film can be used for the same application as a normal pellicle film.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Aihiko Nagata 2-13-1, Isobe, Annaka City, Gunma Prefecture Shin-Etsu Kagaku Kogyo Co., Ltd., Institute for Precision Materials (72) Inventor Shu Kashida Annaka City, Gunma Prefecture 2-13-1, Isobe Shin-Etsu Chemical Co., Ltd. Precision Materials Research Laboratory (72) Inventor Yoshihiro Kubota 2-1-1, Isobe, Annaka-shi, Gunma Shin-Etsu Chemical Industry Co., Ltd.

Claims (2)

[Claims] 1. A pellicle for lithography, characterized in that the pellicle film is composed of a multilayer film of at least two kinds of amorphous fluoropolymers. 2. The pellicle film has a tensile yield strength of 30 MPa.
As described above, an amorphous fluoropolymer film having an initial tensile modulus of less than 1.4 GPa and an amorphous fluoropolymer film having a tensile yield strength of less than 30 MPa and an initial tensile modulus of 1.4 GPa or more are alternately used. The pellicle for lithography according to claim 1, wherein the pellicle for lithography comprises a multi-layer film of at least two layers superposed on each other.