KR20110116964A - Method for coating adhesive on inner wall of air hole in pellicle frame - Google Patents

Abstract

[PROBLEMS] To provide a method for applying an adhesive to an inner wall of a vent hole of a pellicle frame having excellent coating uniformity without contaminating the surrounding environment.
[Solution] The pellicle frame is formed by holding the frame such that the outer surface of the pellicle frame having air holes is inclined horizontally or 45 degrees or less, and dropping the pressure-sensitive adhesive diluted to 10% by mass or less with an organic solvent toward the air holes. A method of applying the pressure-sensitive adhesive on the inner wall of the air vent, characterized in that the organic solvent is a mixed solvent formed by mixing ethyl acetate and hexane in a mixing ratio of 3: 7 to 5: 5.

Description

How to apply adhesive to the inside wall of the pellicle frame vents {METHOD FOR COATING ADHESIVE ON INNER WALL OF AIR HOLE IN PELLICLE FRAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pellicle for lithography, which is used as a dust cover when manufacturing a semiconductor device, a printed board, a liquid crystal display, and the like, and more particularly, to a method for applying an adhesive to an inner wall of a pellicle frame.

In the manufacture of semiconductor devices such as LSI and ultra-LSI, or in the manufacture of liquid crystal displays, a process of fabricating a pattern by irradiating light onto a semiconductor wafer or a liquid crystal display plate is included. However, a photomask or reticle (hereinafter, simply a photo) used at this time is used. If the dust adheres to the dust, the dust absorbs light or refracts the light, so that the transferred pattern is deformed or the edges are unclear. There was a problem of damage.

For this reason, although the said operation is normally performed in a clean room, it is still difficult to keep a photomask clean all the time. Therefore, exposure after attaching a pellicle as a dust film on the surface of a photomask is performed. In this case, the foreign matter is not directly attached to the surface of the photomask but is attached on the pellicle, so that when lithography focuses on the pattern of the photomask, the presence of the foreign material on the pellicle does not adversely affect the transferred pattern.

In general, a pellicle is formed by attaching or adhering a transparent pellicle film selected from nitrocellulose, cellulose acetate, fluorine resin, or the like which transmits light well to the top surface of a pellicle frame selected from aluminum, stainless steel, polyethylene, or the like.

In addition, an adhesive layer selected from polybutene resin, polyvinyl acetate resin, acrylic resin, and the like, and a release layer (separator) for the purpose of protecting the adhesive layer are formed at the lower end of the pellicle frame.

In addition, a thin adhesive layer may be formed on the inner surface of the pellicle frame. This prevents defects from occurring in the pattern by capturing foreign substances that enter or enter the internal space of the pellicle into the pressure-sensitive adhesive layer, and prevent the foreign material from falling from the pellicle frame surface on the photomask surface after the pellicle is attached. It is made to

Since the pressure-sensitive adhesive layer formed on the inner surface of the pellicle frame does not need to be thick because it is intended to trap foreign matters, and also needs to be applied to the inner surface of the corner portion in the same manner as the straight portion, it is usually formed by the spray method (Patent Document 1).

In addition, in order to eliminate the pressure difference between the space enclosed inside the pellicle and the outside air pressure while the pellicle is attached to the photomask, a small air vent for adjusting the pressure is opened in a part of the pellicle frame, and the air moved through the vent hole. In order to prevent the invasion of foreign matter, a filter may be provided (Patent Document 2).

Moreover, in order to improve the foreign substance trapping ability of the said filter itself, there exist some which impregnate an adhesive solution in a filter in the range which does not affect ventilation property (patent document 3). In addition, as another method for preventing foreign matter from entering the ventilation hole, the shape of the ventilation hole is not simply a straight round hole, but the cross-sectional shape is formed in a "ku" shape to impart resistance to air ingress or further. The method of providing an adhesion layer on the inner wall of a vent hole is proposed (patent document 4).

However, it is not easy to coat the pressure-sensitive adhesive uniformly against the inner wall of the vent hole having a diameter of 1.0 mm or less. When the adhesive is applied to the air vents by the spray method as in the case of the pressure-sensitive adhesive applied to the inner surface of the pellicle frame, the adhesive layer on the spray nozzle side becomes thick, so that a distribution occurs in the thickness and other than the pellicle frame vents, which are the application targets. Since an adhesive adheres to a location, the quality as a pellicle frame becomes inadequate (FIG. 5). In addition, in order to spray spray an adhesive, it is necessary to make a coating liquid low viscosity. This is usually done by solvent dilution, so there is a risk of explosion depending on the type of solvent.

On the other hand, a method of applying using a rod-shaped one other than the spray method is also considered, but it is difficult to form a uniform pressure-sensitive adhesive layer by stabilizing the amount of the pressure-sensitive adhesive to be supplied, which is pushed out to the inner surface of the pellicle frame. Many occur (FIG. 6). In addition, since the rod is inserted into the extremely thin air vent, the frame may be damaged and conversely, dust may be generated. Therefore, the method of applying the rod-shaped material is extremely poor in practicality and can be stably used in the mass production process. no.

As a method for solving the above-mentioned problems, a method of filling a pressure-sensitive adhesive solution diluted in a low concentration by a solvent into the air vent and coating the inside of the air vent after the solvent is volatilized is considered. Since the solvent is volatilized from both ends, the solution concentration gradually increases, and thus a pellicle frame of good quality cannot be obtained because a pressure-sensitive adhesive film is formed in the last remaining portion such that the pressure-sensitive adhesive layer is ubiquitous or blocks the air vents.

Japanese Patent Laid-Open No. 64-48062 Japanese Utility Model Publication No. 63-393703 Japanese Patent Laid-Open No. 09-68792 Japanese Patent Laid-Open No. 02-250055 Japanese Patent Laid-Open No. 64-48062

Accordingly, it is an object of the present invention to provide a method of applying an adhesive to a pellicle frame vent, which does not contaminate the surrounding environment and is excellent in coating uniformity.

That is, the present invention maintains the frame so that the outer surface of the pellicle frame having the air hole is inclined horizontally or 45 degrees or less, and the pellicle frame is dropping the pressure-sensitive adhesive diluted to 10% by mass or less with the organic solvent toward the air hole. A method of applying a pressure-sensitive adhesive on the inner wall of the vent hole, wherein the organic solvent is a mixed solvent formed by mixing ethyl acetate and hexane in a mixing ratio in the range of 3: 7 to 5: 5. It is a method of apply | coating an adhesive to the.

In this invention, it is preferable that the said adhesive is resin chosen from a silicone resin, an acrylic resin, and a polybutene resin, and it is preferable that the dripping amount of the diluted adhesive is 0.4-1.0 micrometer.

Effect of the Invention

According to the present invention, a deterioration of the working environment due to the scattering of the pressure-sensitive adhesive and contamination of the pellicle frame can be obtained, and an excellent coating film can be stably obtained without uncoated spots or push-outs.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which shows the example of the application | coating method of this invention which keeps the outer surface of the pellicle frame which has a vent hole horizontally, and apply | coats an adhesive to the inner wall of a pellicle frame vent hole.
2 is an explanatory view showing a state in which the pressure-sensitive adhesive is uniformly applied when the pressure-sensitive adhesive is applied to the inner wall of the frame vent hole by the coating method of the present invention.
It is explanatory drawing which shows the state which the adhesive was partially apply | coated when an adhesive was apply | coated to the inner wall of frame ventilation hole by the comparative method.
It is explanatory drawing which shows the state which the ventilation hole was closed by the adhesive when the adhesive was apply | coated to the inner wall of frame ventilation hole by the comparative method.
It is explanatory drawing which shows the conventional method of apply | coating an adhesive to the inner wall of a pellicle frame vent hole by a spray method.
It is explanatory drawing which shows the method of apply | coating an adhesive to the inner wall of a pellicle frame vent hole by a coating rod.

EMBODIMENT OF THE INVENTION Hereinafter, the application | coating method of the adhesive to the ventilation hole of the pellicle frame of this invention is demonstrated based on drawing.

1 is a view showing the most basic form of the method of applying the pressure-sensitive adhesive on the inner wall of the vent hole of the pellicle frame of the present invention. In FIG. 1, 1 is a pellicle frame, 2 is a ventilation hole, 3 is a droplet of coating liquid, 4 is a coating needle, 5 is a tube which conveys a coating liquid, and 6 is a metering pump.

The pellicle frame 1 having the air vents 2 is fixed so that the outer surface of the pellicle frame is horizontal. In the present invention, the coating liquid 3 made of a pressure-sensitive adhesive diluted with a solvent is removed from the metering pump 6. It is sent out to the coating needle 4 at the tip of the tube through the tube 5, and a coating liquid is dropped into the ventilation hole 2 from the jet port at the tip of the coating needle to apply an adhesive to the inner wall of the ventilation hole 2. The dropwise amount of the coating liquid may be equal to or larger than the volume of the air permeable, and may be usually in the range of 0.4 to 1.0 µl.

The outer side surface of the pellicle frame 1 may be inclined as long as the dropping coating liquid does not contaminate the outer side and inner side of the frame, but is preferably inclined within 45 degrees from the horizontal. The dropping surface may be either the outer surface of the frame or the inner surface of the frame. However, the dropping surface is preferably dropped from the outer surface of the frame from the viewpoint of preventing contamination of the inside of the frame.

The adhesive resin used in the present invention may be appropriately selected from silicone resins, acrylic resins, and polybutene resins. The concentration of the pressure-sensitive adhesive in the coating liquid is intended to capture the foreign matter inside the air vents, and does not need to be thickened. Therefore, the concentration of the pressure-sensitive adhesive in the coating liquid is basically set to decrease the concentration so that uncoated portions do not occur during application. . Specifically, the concentration is preferably 10% by mass or less to avoid troubles such as covering the membrane inside the air vents.

Drying in the vents starts from both ends of the vents, but since the area for volatilization of the solvent is extremely small, it is preferable to select a solvent having a low boiling point as a diluent solvent used for drying the solvent quickly. However, if a solvent with high solubility is selected, the concentration of the solution increases as the drying proceeds, and the amount of the adhesive adhered to both ends of the initially dried vents decreases, resulting in a thinner coating film. Consideration should also be given to solubility. From these viewpoints, in this invention, ethyl acetate: hexane is used combining them in the range of 3: 7-5: 5 (mass ratio).

Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not limited by this.

Example 1

An aluminum alloy frame having an outer dimension of 149 x 122 mm, an inner dimension of 145 x 118 mm, a height of 5.8 mm, an inner dimension of a corner portion R3 mm and an outer dimension of R3 mm was fabricated, and a vent hole having a diameter of 0.5 mm was formed on one short side. After that, black anodize was applied to the surface to form a rectangular aluminum alloy pellicle frame.

The obtained pellicle frame was brought into a clean room of class 1, washed well with a neutral detergent and pure water, and dried, and then the pellicle frame was fixed so that the outer wall of the pellicle frame having the ventilation holes was horizontal as shown in FIG. The coating liquid 3 was dripped at (2), the adhesive was apply | coated to the inner wall of air permeability, and the result was evaluated.

As a metering pump 6 for supplying the coating liquid, a tubular dispenser (manufactured by ISMATEC) was used, and the coating liquid was supplied to the coating needle 4 made of SUS through the tube 5. The coating liquid used a mixed solvent of hexane (boiling point 69.0 ° C) and ethyl acetate (boiling point 77.1 ° C) as a diluent for pressure sensitive adhesive, and 5 masses of silicone pressure sensitive adhesive (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KR-3700). Diluted to% to prepare.

Ethyl acetate has a lower solubility in silicone pressure sensitive adhesives than toluene, which is a common solvent of silicone resins. On the other hand, when toluene is used as a diluent, the solution concentration increases as the drying proceeds, so that the problem that hardly any adhesive remains in the part to be dried initially occurs. There is a characteristic that the drying proceeds while leaving an adhesive on the part. In addition, hexane is a solvent having a very low solubility in a silicone resin, but has a low boiling point, resulting in an increase in drying speed.

Therefore, in the present embodiment, 5% by mass of a silicone adhesive (Shin-Etsu Chemical Co., Ltd. make, brand name: KR-3700) was used with the diluent which mixed ethyl acetate and hexane in various mixing ratios in consideration of the characteristic of each solvent. Several types of coating liquids diluted to be prepared were prepared and the experiment was performed.

The coating was performed by setting the coating needle 4 near the vent hole 2 on the outer side of the frame and dropping the coating liquid in the appropriate amount on the inner surface of the vent hole 2. The said titration amount is the quantity calculated | required from the conditions previously so that nothing may bleed out from an inner surface. After drying by air drying, only the pellicle frame 1 was heated to 120 degrees by a high frequency induction heating apparatus to completely remove the solvent and to completely crosslink the adhesive. In the meantime, contamination of the coating apparatus and the surrounding environment according to the operation did not occur at all.

As described above, the pellicle frame 1 in which the pressure-sensitive adhesive film was formed on the inner wall of the vent hole 2 was cut at the portion of the vent hole 2, and then, under a microscope, for the pressure-sensitive adhesive film formed on the inner wall of the vent hole. The situation was observed. The results are as shown in Table 1.

sample
No . silicon
Suzy mix
menstruum mix Solvent ratio Exterior Ethyl acetate Hexane occlusion Uniformity One 5% 95% 0% 100% none × 2 5% 95% 10% 90% none × 3 5% 95% 20% 80% none × 4 5% 95% 30% 70% none ○ 5 5% 95% 40% 60% none ○ 6 5% 95% 50% 50% none ○ 7 5% 95% 60% 40% has exist × 8 5% 95% 70% 30% has exist × 9 5% 95% 80% 20% has exist × 10 5% 95% 90% 10% has exist × 11 5% 95% 100% 0% has exist ×

Sample No. with high usage rate of hexane In the case of 1 to 3 (ethyl acetate: hexane = 0: 100 to 20:80), the drying rate was fast and the blockage of the air vents was not observed due to the pressure-sensitive adhesive. The thickness of the coating film was uneven (FIG. 3). On the other hand, Sample No. with high ethyl acetate ratio. In the case of 7 to 11 (ethyl acetate: hexane = 60: 40 to 100: 0), the drying rate is slow and the solubility of the ethyl acetate in the adhesive is high. Occlusion occurred (FIG. 4).

On the other hand, the sample No. In the case of 4-6 (ethyl acetate: hexane = 30: 70-50: 50), as shown in FIG. 2, the inner wall of the vent hole 2 of the pellicle frame 1 is uniformly covered with adhesive, and the vent hole No blockage was seen. The film thickness of the applied adhesive was measured by reading the focal difference between the frame surface of the microscope and the pressure-sensitive adhesive surface on the Z stage, which was approximately 13 to 17 µm over the entire vent hole surface. Moreover, the push-out and slack of the adhesive other than the outer surface were not seen, either. As for the foreign matter, one having a problem size (20 µm or more in diameter) was not found.

Subsequently, in order to evaluate the performance of capturing foreign matters, a polystyrene resin having a thickness of 130 μm was attached to the inner wall of the vent hole 2, and then the direction of the vent hole using an air gun set to 4.0 kgf / cm 2 of the original pressure. Air blow was performed at a distance of 10 mm from the frame for 10 seconds. As a result, in all of the cases 4 to 6, it was confirmed that the increase and decrease and the movement of the foreign matter were not confirmed, and that a film thickness sufficient to capture the foreign matter was obtained.

Comparative Example 1

The sample was prepared like Example using the silicone adhesive (Shin-Etsu Chemical Co., Ltd. make, brand name: KR-3700) diluted to 3% with toluene (boiling point 110.6 degreeC) as a coating liquid. As a result of observing the coating state inside the vent hole under a microscope by cutting the test frame at the vent part, as shown in FIG. 3, the pressure-sensitive adhesive was localized near the center of the vent hole and almost no adhesive was coated at both ends. Did.

Comparative Example 2

The sample was prepared like Example using the silicone adhesive (Shin-Etsu Chemical Co., Ltd. make, brand name: KR-3700) diluted 5% with toluene (boiling point 110.6 degreeC) as a coating liquid. As a result of observing the coating state inside the vent hole under a microscope by cutting the frame produced in the test part, as shown in FIG. 4, it was confirmed that an adhesive film was formed and occluded near the center of the vent hole.

The present invention can prevent excessive waste of the adhesive and solvent, and at the same time, there is no deterioration of the working environment due to scattering of the adhesive or contamination of the pellicle frame, and a working space for forming the adhesive layer on the inner wall of the pellicle frame ventilator. The present invention is extremely useful in the industrial field using lithography technology because of its narrowness, it is possible to easily and efficiently form a uniform adhesive film on the inner wall of the pellicle frame vent.

1: pellicle frame 2: ventilator
3: coating liquid 4: coating needle
5: liquid feeding tube 6: metering pump
7: adhesive layer adhered to the inner wall of the vent
8: Area where the adhesive is ubiquitous on the inner wall of the vent
9: The part where adhesive is not attached to the inside wall of ventilation hole
10: part where the inner wall of the vent hole is blocked by the adhesive film
11: spray 12: application rod

Claims (3)

The frame is held so that the outer surface of the pellicle frame having the air holes is inclined horizontally or 45 degrees or less, and the pressure-sensitive adhesive diluted to 10% by mass or less with an organic solvent is dropped onto the air hole inner wall of the pellicle frame. As a method of applying the pressure-sensitive adhesive:
And said organic solvent is a mixed solvent obtained by mixing ethyl acetate and hexane in a mixing ratio in the range of 3: 7 to 5: 5. The method of claim 1,
The pressure-sensitive adhesive is a method for applying the pressure-sensitive adhesive on the inner wall of the vent hole of the pellicle frame, characterized in that the pressure-sensitive adhesive is selected from silicone resin, acrylic resin, polybutene resin. The method according to claim 1 or 2,
Method of applying the pressure-sensitive adhesive on the inner wall of the vent hole of the pellicle frame, characterized in that the dropping amount of the diluted pressure-sensitive adhesive is 0.4 ~ 1.0㎛.

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