KR101618558B1 - Method of making protection layer onto the surface of photomask - Google Patents

Abstract

A method of forming a photomask protective coating layer, comprising: coating a UV curable coating on the photomask of plastic material; and UV curing the coated UV curable coating to form a photomask protective coating layer without a thermal process Is presented.
According to the method of the present invention, it is possible to simplify the production process and to reduce the process cost by omitting the thermal process as a UV-free, solvent-free UV coating which does not require a heating and drying process. It is an applicable process. By replacing the protective film composed of a multilayer, the surface protective layer is made into a single layer, thereby improving the refraction and scattering occurring in the photomask working, thereby realizing a more precise microcircuit and improving the quality of the substrate. It is possible to improve the cost and defects in the adhesive process itself by replacing the adhesive process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a photomask,

The present invention relates to a photomask film used in a semiconductor or printed circuit board production process, and more particularly, to a method for forming a protective layer on the photomask film.

Protective films are generally used as a treatment method for protecting the surface of photomask films used in semiconductor or printed circuit board production processes.

FIGS. 1 and 2 show a single layer structure and a protective film layer formation process in which such a general protective film is formed as a protective layer.

The protective film layer is generally used to prevent damage to the surface of a photomask of a plastic material having a severe dimensional change due to heat when manufacturing a PCB substrate and to secure a number of reuse times. The thickness of the protective film layer is generally 8 to 12 μm . At this time, the surface of the protective film used is coated with a UV paint excellent in releasability and scratch resistance.

However, the protective film is a triple structure of a surface protective layer, a film layer and an adhesive layer, which may cause deterioration of the quality of the photomask.

On the other hand, a method of forming a single protective layer by replacing the protective film may be used. In this way, there is currently a solvent-based UV curing type solvent-based paint. These paints are only partially applied to inorganic materials (glass substrates and quartz substrates) with little thermal deformation. However, such a thermosetting UV curing type paint has problems such as increase of production cost by heat treatment process and generation of VOC due to volatilization of solvent, and it is applied to a photomask of a plastic material (PET, PI, etc.) There is a disadvantage that it is difficult to do.

On the other hand, Korean Patent No. 10-0800010 discloses a method for forming a photomask protective layer of a solvent type thermal curing method on a photomask original plate having a protective layer with a protective film, a method for producing the same, and a protective layer forming liquid for photomask original plate, In the case where the material of the photomask is an inorganic material such as glass or quartz, a substrate is formed on the material, and then a protective film is formed by using a mixed resin of a fluororesin and an acrylic resin in place of the protective film, A crosslinking curing agent obtained by mixing a polyisocyanate prepolymer with ethyl acetate and a crosslinking curing agent obtained by mixing a polyisocyanate prepolymer and ethyl acetate with a solvent mixture of n-butyl acetate and methyl (meth) A combination of ethyl ketone (MEK) and a cellulosic acetate (ethylene glycol monoethyl ether) diluent is applied, Thereby forming a protective layer (see FIG. 3).

Meanwhile, Korean Patent Laid-Open No. 10-2004-0012453 (a method of forming a surface protective coating of a photomask coating and a photomask) discloses a method in which a UV curing type is mixed with such a hot pressing method. However, The present invention provides a method for forming a surface protection coating of a photomask coating and a photomask capable of forming a surface protective coating which can be easily removed at a low temperature and can be cured at a low temperature and has a high ultraviolet transmittance, chemical resistance, hardness and releasability (See Fig. 4)

With this paint, the patent presents the following composition.

(Composition ratio and composition ratio of Example 1 of 10-2004-0012453) Raw material Weight portion Polyphenylsilane 16 Epoxy resin 8 Photoacid generator 0.8 Surface conditioner 0.1 Silicon compound 0.25 solvent 74.85 Sum 100

However, the above-mentioned prior art has the following problems.

1. General way

1-1 How to attach protective film

Protective films formed of a pressure-sensitive adhesive layer and a film layer have limitations in circuit implementation of 30 μm or less due to a decrease in light transmittance, and pin holes due to micro-air layers generated during a sticking process are frequently generated. There is a problem that the mass production rate is significantly lowered due to the influence of moisture.

1-2 No treatment

In the non-treated state, the photomask reuse ratio is drastically lowered (cost increase) due to surface damage such as scratches and dirt, etc., generated in the surface layer of the photomask during the operation, There is a problem that the mass production rate is remarkably lowered due to the influence of the deformation caused by the surface being exposed to moisture.

2. Solvent type heat-hardening method.

The method of aging at room temperature and curing is applicable to plastic photomask. However, since the coating liquid used is a two-liquid type, it takes a certain time to cure and there is a disadvantage that the working water amount is very limited. There is a drawback that a large amount of an organic solvent must be used as a diluent.

However, since this technique also requires the use of a volatile organic solvent in order to lower the viscosity of the thin film coating process, it is necessary to use a thermal agent for volatilization of the organic solvent Process or a separate aging process is required. In addition, it can be applied to glass photomask in thermal process, but it is difficult to apply to plastic photomask in which dimensional change due to heat is severe.

3. Thermal UV curing system

This method uses a polymer having a high viscosity. In this case, a large amount of a volatile organic solvent is required to maintain the thin film coating conditions of 3 μm or less and the workable viscosity of the coating. In addition, It is necessary to pre-baking for volatilization of the organic solvent (pre-baking step for heating to a temperature in the range of 70 to 120 占 폚). Such a thermal process can be applied to the formation of a surface protective layer of a glass photomask, but it is difficult to apply it to a plastic photomask having a large dimensional change due to heat.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of implementing a surface protection layer having superior performance on a photomask on which a designed electronic circuit pattern is formed in a more environmentally friendly and economical manner .

Another object of the present invention is to improve the quality of the photomask produced by the multi-layered protective film by directly coating (single layer) on the surface of the photomask in place of the protective film.

In order to accomplish the above object, the present invention provides a method of forming a protective coating for a photomask, comprising the steps of: coating a UV curable coating material on the photomask of a plastic material (PET, PI (Polyimide) A step of UV-curing the coating; and a method of forming a photomask protective coating layer without a thermal process.

The method of the present invention uses the UV curing method which does not require a drying step by heat, and has the following advantages.

① As a UV coating without a heating and drying process, it is possible to simplify the production process and reduce the process cost by omitting the thermal process.

② It is applicable not only to inorganic materials but also to photomasks of various plastic materials with low heat resistance.

③ By replacing the multi-layered protective film, it is possible to improve the quality of the substrate by improving the refraction and scattering caused by the photomask working by making the surface protection layer thin.

④ By replacing the process of sticking the protective film, it is possible to improve the cost and defects in the sticking process itself.

UV curable paints that can be used in the process of the present invention include UV oligomers (GMA (Glycidyl meta acrylate) and BMA (buthyl meta acrylate) base oligomers) having a viscosity of 200 cps / 25 DEG C or lower and TMPTA (Trimethylolpropane Triacrylate) : 0.5 to 1: 0.05, and 1 to 5 parts by weight of a photoinitiator relative to 100 parts by weight of the UV oligomer and silica sol. The UV curable coating material may be a coating material having an effective content of 97% or more. With an effective content of 97% or more, a thermal process is not necessary.

According to the method of the present invention, it is possible to simplify the production process and to reduce the process cost by omitting the thermal process as a UV-free, solvent-free UV coating which does not require a heating and drying process. It is an applicable process. By replacing the protective film composed of a multilayer, the surface protective layer is made into a single layer, thereby improving the refraction and scattering occurring in the photomask working, thereby realizing a more precise microcircuit and improving the quality of the substrate. It is possible to improve the cost and defects in the adhesive process itself by replacing the adhesive process.

1 to 4 show a conventional method of forming a photomask protective layer,
Figure 5 is a diagrammatic illustration of the method of the present invention,
6A is a photograph of the surface protective layer of the photomask film of Comparative Example 1,
6B is a photograph of the surface protective layer of the photomask film of Example 1 according to the present invention,
7 is an electron micrograph of an electronic circuit pattern developed after exposure using the photomask films of Example 1 and Comparative Example 1 according to the present invention.

Hereinafter, embodiments of the present invention will be described.

Example 1

26.5 parts by weight of a UV oligomer (oligomer of GMA (glycidyl meta acrylate) and BMA (buthyl meta acrylate) base) manufactured by APEC CHEMICAL Co., Ltd., 30 parts by weight of Optisol-ASAM3100 (TMPTA base silica sol) 8 parts by weight of DPHA (Dipentaerythritol Hexaacrylate), 10 parts by weight of 2-HEMA (2-Hydroxyethyl methacrylate), 20 parts by weight of HDDA (1,6-Hexanediol Diacrylate), 2 parts by weight of Ethyl Acetate, 3 parts by weight of cyclohexyl-phenyl-ketone and 0.5 parts by weight of DAROCUR TPO (Diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide, BASF) were mixed to prepare a UV- , Specific gravity: 1.07, water content: 0.5%)

The coating material thus prepared was coated on a photomask film having a width of 55 cm and a length of 66 cm and coated with a coating agent to a thickness of about 5 μm and cured by UV irradiation at 600 mJ / cm 2.

Comparative Example 1

A TACKWELL # 155R HD film of SEKISUI Co., Ltd. was laminated on the photomask film having a width of 55 cm and a length of 66 cm and removing the silver oxide.

Comparative Example 2

A photomask film having a width of 55 cm and a length of 66 cm and having silver oxide removed thereon was subjected to no treatment.

Evaluation of the above-formed photomask surface protective layer

The obtained surface protecting layers of Comparative Examples 1 and 2 were evaluated for the following items.

Appearance: The surface protective coating was observed with naked eyes under a white fluorescent lamp, and when no appearance defects such as cracks or turbidity were observed, it was rated as & cir &

- Light transmittance and haze: A coating agent was applied to the photomask film from which the silver oxide layer had been removed, and after UV curing, the haze was measured with a haze meter (NIPON DENSHOKU, NDH-5000).

- Pencil hardness: Measured according to JIS K5400.

- Water resistance (Benchotte rubbing): Rubbed with a wiping cloth containing pure water, and the presence or absence of surface change was observed under a microscope. A surface change was not observed and a surface change was observed.

- Ethanolicity (Benchtop rubbing): rubbed with a wiping cloth containing ethanol, and observed with a microscope for surface changes. A surface change was not observed and a surface change was observed.

- Adhesiveness (checkerboard tape peeling): Measured according to JIS K5400.

- Antifouling property: Marked as oil-based magic, allowed to stand in a room at 23 ° C for 24 hours, rubbed with a wiping cloth containing ethanol, and observed with a microscope for signs or marks. &Quot; A "," X "

- Water repellency: pure water was dropped using a dropper, and the wet state was visually observed. The water repellency was observed as & cir &

Table 2 summarizes the above results.

Item Example 1 Comparative Example 1 Comparative Example 2 Exterior ○ ○ ○ Light transmittance 88.74 88.72 88.49 Hayes 3.13 4.54 6.4 Pencil hardness 2 ~ 3H 6B H Water resistance ○ ○ ㅧ My ethanolic ○ ○ ㅧ Adhesiveness 100/100 Damage in Cross Cut 100/100 Antifouling ○ ○ ㅧ Water repellency ○ ○ ㅧ

As described above, it can be confirmed that the photomask protective coating layer formed according to the method of the present invention shows much better properties than the comparative example.

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Claims (2)

A method of forming a photomask protective coating layer,
Coating a UV curable paint on the photomask of plastic material;
A method for forming a photomask protective coating layer without a thermal process, comprising UV curing the coated UV curable coating material,
The UV-
A UV oligomer having a viscosity of 200 cps / 25 ° C or less and a viscosity of less than 200 cps / 25 ° C, prepared by mixing GMA (Glycidyl meta Acrylate) monomer and BMA (Buthyl meta acrylate)
A TMPTA base silica sol prepared by mixing a silica sol with an oligomer synthesized by TMPTA (trimethylolpropane triacrylate)
A weight ratio of 1: 0.5 to 1: 0.05,
Wherein the photoinitiator comprises 1 to 5 parts by weight of the UV oligomer and 100 parts by weight of the TMPTA base silica sol,
Wherein the UV curable coating material has an effective content of 97% or more. delete

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