JP2008175874A - Application method of pressure-sensitive adhesive on pellicle frame inner face - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an application method of an adhesive on a pellicle frame inner face, the method excellent in the application quality and its stability without contaminating the surrounding environment. <P>SOLUTION: A pressure-sensitive adhesive is applied by holding a pellicle frame 11 with one inner face substantially kept horizontal and directing upward and moving a discharge port while dropping the pressure-sensitive adhesive diluted with a solvent from the discharge port 16. This prevents contamination in the work environment or the pellicle frame due to splashing of the adhesive and stably gives a coating film with excellent appearance free from an uncoated portion or protrusion. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a pellicle for lithography used as a dust remover when manufacturing a semiconductor device, a printed circuit board, a liquid crystal display, or the like, and particularly relates to a method for applying an adhesive to the inner surface of a pellicle frame. .

In the manufacture of semiconductors such as LSI and VLSI, or the manufacture of liquid crystal displays, patterns are produced by irradiating a semiconductor wafer or liquid crystal master plate with light. A photomask or reticle (hereinafter simply referred to as a photomask) used at this time is used. If the dust adheres to the (describe)), the dust will absorb light or bend the light, so the transferred pattern will be deformed, the edges will be sticky, and the ground will be stained black. There was a problem that dimensions, quality, appearance, etc. were impaired.
For this reason, these operations are usually performed in a clean room, but it is still difficult to keep the photomask clean.

Therefore, exposure is performed after a pellicle is attached to the surface of the photomask to prevent dust. In this case, the foreign matter does not adhere directly to the surface of the photomask but adheres to the pellicle. Therefore, if the focus is set on the pattern of the photomask during lithography, the foreign matter on the pellicle becomes irrelevant to the transfer.
In general, a pellicle has a transparent pellicle film made of nitrocellulose, cellulose acetate, fluororesin, or the like that transmits light well, and is attached or bonded to the upper end surface of a pellicle frame made of aluminum, stainless steel, polyethylene, or the like.

Further, an adhesive layer made of polybuden resin, polyvinyl acetate resin, acrylic resin or the like for mounting on a photomask, and a release layer (separator) for the purpose of protecting the adhesive layer are provided at the lower end of the pellicle frame.
Then, in the state where the pellicle is attached to the photomask, a small hole for adjusting the atmospheric pressure is formed in a part of the pellicle frame in order to eliminate the pressure difference between the space enclosed inside the pellicle and the outside. There is a case where a filter is installed to prevent foreign substances from entering through the air moving through (Patent Document 1).

In addition, a thin adhesive layer may be provided on the inner surface of the pellicle frame. The purpose of this is to prevent foreign matter that has entered or generated in the internal space of the pellicle from being trapped in the adhesive layer, and to prevent the occurrence of pattern defects after the pellicle is attached by preventing the foreign matter from dropping from the surface of the pellicle frame. .
This adhesive layer is usually formed by a spraying method because it is not necessary to have a thickness because it is intended to trap foreign matter, and the inner surface of the corner portion needs to be coated in the same manner as the straight portion (Patent Document 2).

As mentioned above, when the adhesive is applied to the inner surface by the spray method, if the conditions such as the size of the spray particles and the coating film thickness are properly selected, the quality of the coating film is uniform and good in appearance. However, there are various problems with manufacturing.
First, since it is not preferable in terms of quality that an adhesive adheres to a part other than the inner surface of the target pellicle frame, in order to prevent this, it is necessary to perform masking so that spray particles do not adhere to unnecessary portions. Although a disposable thing like a masking tape can be used for masking, since this is not suitable for mass production, a dedicated masking jig as shown in 34 in FIG. 3 is generally used.

  Masking jigs can be designed relatively easily, and if the shape is appropriate, stable coating quality can be obtained, but the adhesive that adheres to the masking jig is wasted and the adhesive accumulates as it is used. Therefore, there is a problem that it must be removed and cleaned periodically. Of course, the inside of the device other than the masking jig is also contaminated by the scattered adhesive spray particles, so that it becomes sticky over time, and periodic cleaning is also necessary. In particular, in the case of a large pellicle whose one side exceeds 500 mm, since the apparatus is also large, these problems become particularly significant.

In general, it is necessary to reduce the viscosity in order to spray the adhesive. Since this is generally performed by solvent dilution, there is a risk of explosion depending on the type of solvent.
On the other hand, in order to solve these problems, a method of applying using a roller-like material instead of a spray method has been proposed (Patent Document 3). However, in these methods, it is difficult to stably supply the pressure-sensitive adhesive to the roller portion, and often protrudes from the inner surface of the pellicle frame or, on the contrary, uncoated portions often come out. Further, contact marks of roller parts are generated on the surface of the frame and the appearance is often deteriorated, so that it is extremely impractical and cannot be stably used in a mass production process. Therefore, until now, there has been no application method that can be practically used for mass production of the pressure-sensitive adhesive on the inner surface of the pellicle frame by which a good application quality can be obtained by a method other than the spray method.

Japanese Utility Model Publication No. 63-39703 JP-A 64-48062 Japanese Patent No. 3415683

  In view of the above, an object of the present invention is to provide a method for applying an adhesive to the inner surface of a pellicle frame that does not pollute the surrounding environment and is excellent in application quality and stability.

The method of applying the adhesive to the inner surface of the pellicle frame according to the present invention is such that the pellicle frame is held so that one inner surface is substantially horizontal and upward, and the adhesive diluted with the solvent is dropped from the outlet. The pressure-sensitive adhesive is applied by moving the film (claim 1).
At this time, the dropping amount of the adhesive during application is preferably controlled according to the moving speed of the discharge port and the position of the discharge port on the pellicle frame.
In addition, if the above-described coating method is applied to the inner surface of the pellicle frame after applying the adhesive to the inner surface of the vent hole provided in the pellicle frame (Claim 3), the inner surface of the vent hole is blocked. The adhesive can be applied to the vent hole and the inner surface of the pellicle frame without causing any trouble.
The outer width of the tip of the discharge port may be 50% or more of the inner width of the pellicle frame.
Furthermore, the distance between the tip of the discharge port during application and the surface of the pellicle frame is in the range of 0.2 to 2 mm, and the gap between the tip of the discharge port and the surface of the pellicle frame is filled with the adhesive. Good (claim 5).

  According to the method of applying the adhesive to the inner surface of the pellicle frame of the present invention, there is no contamination of the working environment and the pellicle frame due to the scattering of the adhesive, and there is no unapplied or protruding, and the coating film is excellent in appearance. It can be obtained stably.

Hereinafter, an embodiment of a method for applying an adhesive to the inner surface of a pellicle frame according to the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows the most basic form of a method of applying an adhesive to the inner surface of a pellicle frame according to the present invention. The pellicle frame 11 is held in a jig hole by a frame-shaped holding jig 12 and fixed so that one of the inner surfaces is horizontal. Then, an adhesive diluted with a solvent is filled in the syringe 14 and the like, and coating is performed by moving along the pellicle frame 11 while dripping it from the discharge port at the tip of the coating needle 15.

When one side is finished, the adhesive is dried to such an extent that it does not flow, and then the direction of the pellicle frame 11 is changed together with the holding jig 12, and this time, the other side is horizontally applied. This is repeated to apply all four sides. Incidentally, not only a general quadrangular shape but also an octagonal frame can be applied in the same manner.
As the discharge means for the adhesive, various pumps such as a plunger pump, a syringe pump, and a tube pump can be used in addition to simple air pressurization, and may be appropriately selected according to the properties and production quantity of the adhesive to be used.

  The viscosity (concentration) of the pressure-sensitive adhesive is preferably determined appropriately in consideration of the size of the frame to be applied and the film thickness after drying. In the case of the internal pressure-sensitive adhesive, it is not necessary to increase the film thickness. Therefore, it is basically better to reduce the viscosity (concentration) so that it is difficult for uncoated coating to occur during coating. However, although it is easy to apply if the viscosity is too low, the adhesive will flow (bias) to the center of the side due to the downward deflection due to the weight of the frame, and the time until drying will increase and productivity will decrease. These points need to be taken into account as problems arise.

  The application needle 15 is preferably inclined as shown in FIG. 1 so as not to interfere with the other inner surface orthogonal to the application surface. The moving means preferably uses a robot or the like so that the moving speed and the position of the application needle 15 can be finely controlled. Further, it is desirable to control the dropping amount of the adhesive during application according to the moving speed of the application needle 15 and the position of the application needle 15 on the pellicle frame 11. In other words, in the vicinity of the corner, discharge a large amount so that the adhesive rises due to surface tension even on the vertical side, and balance the movement speed and discharge amount so that there is no uncoated part or protrusion in the straight part. Is good.

  At this time, if a vent hole is provided in the pellicle frame 11, the pressure-sensitive adhesive may form a film depending on the application condition, and the vent hole may be blocked. In order to prevent this, it is effective to prevent the adhesive needle from passing directly above the vent hole when moving the application needle, or to temporarily stop the discharge of the adhesive at the portion passing through the vent hole. However, even though these methods can prevent the clogging of the vent holes, it is difficult to stably apply the adhesive to the inner surface of the vent hole, so only the vent holes are applied before the adhesive is applied to the inner surface of the pellicle frame. It is most preferable to apply the adhesive under optimum conditions.

  Further, the shape of the application needle 15 and the discharge port 16 at the tip is simple in the shape of a circular pipe, but may be a shape as shown in FIG. Here, the cross-sectional shape of the application needle 22 and the discharge port 24 itself are circular, but a bar-shaped width expanding member 23 for the purpose of spreading the adhesive solution is attached to the tip. In the example of FIG. 2, a cylindrical member is attached, but the object can be achieved by other shapes such as a prismatic shape, and the shape of the discharge port 24 may be an ellipse or a slit shape instead of a circle.

Here, the length of the width expanding member 23 is preferably 50% or more with respect to the inner width of the pellicle frame (the length in the direction perpendicular to the ejection port movement direction). In addition, the distance between the tip of the application needle 22 and the width expanding member 23 during application and the surface of the pellicle frame 21 is in the range of 0.2 to 2 mm, and is adjusted as appropriate so that the gap is filled with the adhesive solution by capillary action. It is desirable.
When such an application needle is used, it can be applied without application even with a smaller amount of liquid compared to a normal circular needle, thus improving the appearance in addition to saving the application liquid and shortening the air drying time. I can expect.

Examples of the present invention will be described below, but the present invention is not limited thereto.
[Example 1]
FIG. 1 shows a schematic diagram of an embodiment according to the present invention.
First, it is made of rectangular aluminum alloy with outer dimensions 1146 × 1366mm, inner dimension 1122 × 1342mm, height 6mm, corner inner dimension R2mm, outer dimension R6mm, and four vent holes 1.5mm in diameter on each long side A pellicle frame was manufactured by machining, and the surface was black anodized.

This pellicle frame was carried into a class 1 clean room, washed and dried well with a neutral detergent and pure water, and then evaluated for application of an inner surface adhesive.
A jig hole is provided on the outer side of the long side of the pellicle frame 11, and the pin 13 installed on the holding jig 12 made of aluminum alloy is supported by being inserted therein. Then, the holding jig 12 was set up vertically so that the inner surface of the pellicle frame 11 was horizontal, and fixed by fixing means (not shown) using an air cylinder.
An air pressure dispenser (manufactured by Iwashita Engineering Co., Ltd., not shown) is used as the means for applying the internal pressure-sensitive adhesive, and the silicone pressure-sensitive adhesive (Shin-Etsu Chemical Co., Ltd. Co., Ltd., trade name: KR-3700).

The syringe 14 was tilted at an angle of 30 ° when viewed from the vertical direction so as not to interfere with the inner surface of the pellicle frame other than the coating surface, and mounted on the tip of a bracket (not shown) attached to the XYZ orthogonal three-axis robot. A SUS needle (inner diameter 0.25 mm) was attached to the tip of the syringe 14.
As a coating operation, first, the needle 15 was moved to the vicinity of the vent hole, and an appropriate amount of adhesive was dropped on the inner surface of the vent hole. At this time, the amount of the liquid to be dripped was determined in advance under conditions so that there was no oozing out from the outer surface and a film was not blocked by forming a film in the vent hole.

Next, the needle 15 was moved to the corner part of the pellicle frame and moved at a constant speed of 4 mm / s while applying an appropriate amount from side to side. At this time, the needle 15 was moved so as not to pass through the vent hole so that the dropped adhesive solution did not enter the vent hole. Then, in the vicinity of the corner portion, it was moved upward in accordance with the R shape of the corner, and coating was performed so that the vicinity of the end of R was covered with the adhesive solution.
Then, after leaving it to stand for about 3 minutes until it is dried to such an extent that the applied adhesive solution does not flow, it is removed from the applicator together with the holding jig 12 and rotated 90 degrees so that the short side becomes horizontal next. The adhesive was applied to the inner surface of the pellicle frame 11 in the same manner.

This operation was repeated to apply the adhesive to all of the long side and the short side, and dried by air drying. Thereafter, only the pellicle frame 11 was heated to 120 ° C. with a high-frequency induction heating device, and the solvent was completely dried and the adhesive was completely cured.
When the amount of liquid used for coating was examined after the work was completed, it was about 35 cc. In addition, there was no contamination of the coating device or the surrounding environment during the work.
The test sample thus produced was transported to a dark room, and the appearance of the internal pressure-sensitive adhesive coated surface and the state of foreign matter adhesion were observed with a halogen lamp with a light intensity of 300,000 lux.

The inner surface of the pellicle frame was completely covered with the pressure-sensitive adhesive, and the pressure-sensitive adhesive protruded beyond the inner surface, and no sagging was observed. The pressure-sensitive adhesive was applied to the outer surface of the ventilation hole as far as it could be visually confirmed, and the ventilation hole was not blocked. In the vicinity of the air holes and in the corners, unevenness (subtle unevenness and surface waviness) due to the application of the adhesive was also observed, but it was not particularly problematic. No foreign matter having a problem size (diameter of 20 μm or more) was found.
And the film thickness of the apply | coated adhesive was estimated to be about 40 micrometers, when a part was peeled off with the adhesive tape and the level | step difference was observed with the microscope.

[Example 2]
The tip of the needle 15 was changed to the shape shown in FIG. 2, and the application of the inner surface adhesive was evaluated in exactly the same manner as in Example 1 above. The inner diameter of the needle 22 and the discharge port 24 is also 0.25 mm, the width expanding member 23 attached to the tip is a round bar shape with a diameter of 3 mm, the length is 4 mm, and the needle 22 is attached by press fitting.
As a result of observing the prototype test sample, as in Example 1, the inner surface of the pellicle frame was completely covered with the adhesive, and the adhesive did not protrude beyond the inner surface, and no sagging was seen. Since the coating was thinner than Example 1, the surface gloss and uniformity were increased, and the appearance was superior to that of Example 1.
In addition, the degree of unevenness (subtle unevenness and surface undulation) in the vicinity of the air vents and corners was considerably reduced. No foreign matter having a problem size (diameter of 20 μm or more) was found. Incidentally, when the film thickness was examined by the same method as in Example 1, it was estimated to be about 25 μm.

[Comparative example]
FIG. 3 shows a schematic cross-sectional view when a pressure-sensitive adhesive is applied to the inner surface of the pellicle frame by a conventional spray method as a comparative example.
A pellicle frame 31 was prepared in the same manner as in the above example, washed and dried in the same procedure, and then attached to the same holding jig 32. Further, a masking jig 34 was attached to the upper surface of the holding jig 32. The masking jig 34 is composed of a stainless steel thin plate and an aluminum alloy frame, and has a shape that covers the end face of the pellicle frame 31 and all four sides of the holding jig 32 simultaneously.

These members were horizontally held at a height of about 1200 mm from the floor surface by a simply manufactured stand (not shown).
As an inner surface adhesive solution, a silicone adhesive (trade name: KR-3700, manufactured by Shin-Etsu Chemical Co., Ltd.) diluted to 2% with toluene was filled in the coating solution tank 36. A PTFE tube was connected between the coating liquid tank 36 and the spray nozzle (manufactured by Ikeuchi Co., Ltd., model: BIMJ), and a needle valve (not shown) for adjusting the coating amount was inserted therebetween. Nitrogen was used as a gas source for pressurizing the spray and coating liquid tank 36 to prevent explosion. Reference numeral 37 indicates spraying.

  For the application, a long handle (not shown) attached to the spray nozzle 35 is manually supported so that the speed is approximately 50 mm / s and that the hand is not covered on the pellicle frame 31. The spray nozzle 35 was moved in the major axis or minor axis direction of the pellicle frame 31 and repeated five times. Then, the same operation was sequentially performed on the other three sides to complete the coating operation. In addition, in order to prevent an oxygen deficiency accident due to nitrogen injection, a large exhaust duct (not shown) is installed downstream of the spray injection to exhaust air so that nitrogen does not stay around.

The samples thus produced were observed in the same manner as in the above examples for the appearance and the state of foreign matter adhesion. As a result, the inner surface was completely covered with the adhesive. Although a slight amount of adhesive mist adhered to the end surface of the pellicle frame, it was not particularly problematic because it was covered with a film adhesive or a mask adhesive.
Ventilation holes seemed to have been coated with an adhesive in the 1-2 mm range near the inner surface side entrance, but seemed not to be coated in a range that could be visually confirmed on the outer surface side. . In addition, although there was no problem in appearance, three foreign matters having a diameter of about 50 μm were attached.
Incidentally, when the amount of liquid used for coating was measured after the work was completed, it was about 180 cc. In addition, a thin adhesive film having a thickness of about 0.1 to 0.2 mm is formed on a part of the upper surface of the masking jig 34. Further, the masking jig 34 is laid under the prototype system (floor surface). Adhesive mist was also found in the vinyl sheet and exhaust fan duct.

  The present invention eliminates excessive waste of adhesives / solvents and the like, and requires only a small working space for forming the adhesive layer on the inner surface of the pellicle frame, so that the adhesive layer on the inner surface of the pellicle frame can be simply and efficiently used. It is possible to form and is beneficial to the industrial field using lithography technology.

It is explanatory drawing which shows one Embodiment of the adhesive coating method to the inner surface of the pellicle frame by this invention. It is explanatory drawing which shows an example of the shape of the adhesive discharge port front end by this invention. It is sectional explanatory drawing which shows the adhesive coating method (spray method) to the conventional inner surface.

Explanation of symbols

11 Pellicle frame 12 Holding jig 13 Pin 14 Syringe 15 Application needle 16 Discharge port

21 Pellicle frame 22 Coating needle 23 Width expanding member 24 Discharge port

31 Pellicle frame 32 Holding jig 33 Pin 34 Masking jig 35 Spray nozzle 36 Coating liquid tank 37 Spray spraying

Claims (5)

  The pellicle frame is held so that one inner surface is substantially horizontal and upward, and the adhesive is applied by moving the discharge port while dripping the adhesive diluted with a solvent from the discharge port. Application method of adhesive to inner surface of pellicle frame.   The method for applying an adhesive to the inner surface of a pellicle frame according to claim 1, wherein the dropping amount of the adhesive is controlled according to the moving speed of the ejection port and the position of the ejection port on the pellicle frame.   3. Applying the adhesive to the inner surface of the pellicle frame, wherein the coating method according to claim 1 or 2 is applied to the inner surface of the pellicle frame after applying the adhesive to the vent hole provided in the pellicle frame. Method.   The method for applying an adhesive to the inner surface of a pellicle frame according to any one of claims 1 to 3, wherein the outer width of the tip of the discharge port is 50% or more of the inner surface width of the pellicle frame.   The distance between the tip of the discharge port during application and the surface of the pellicle frame is in the range of 0.2 to 2 mm, and the gap between the tip of the discharge port and the surface of the pellicle frame is filled with the adhesive solution. The method for applying an adhesive to the inner surface of the pellicle frame according to any one of claims 1 to 4.

Images