JPH063807A - Pellicle - Google Patents

Abstract

PURPOSE:To enable the easy discovery of foreign matter at the time of a visual inspection on the foreign matter sticking to the inner side of a frame and to improve reliability by forming the tacky adhesive layer on the inner surface of the frame as a glossy surface. CONSTITUTION:The tacky adhesive layer is formed on the inner flank surface of the frame and the surface thereof is formed as the glossy surface. The glossy surface refers to the surface which is not provided with such ruggedness as to allow the intrusion of the foreign matter of 1 to 20mum therein and cause scattering at the time of irradiation with light and the surface which reflects the light. For example, the pellicle frame made of aluminum (subjected to an anodic oxidation treatment on the surface) formed by masking the surface to be adhered with a pellicle film, double-coated tacky adhesive tape surface and outer surface with tacky adhesive tapes is dipped into an aq. emulsion tacky adhesive. The frame is then dried and thereafter, the tacky adhesive tapes are peeled, by which the tacky adhesive layer having the glossy surface on the inner flank surface of the frame is formed. The pellicle film is adhered to one flank of such frame and the double-coated tacky adhesive tape is stuck to the other flank, by which the pellicle is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pellicle which is a protective dustproof body for a photomask and a reticle (hereinafter abbreviated as "mask") used in a lithography process in a semiconductor integrated circuit.

[0002]

2. Description of the Related Art In manufacturing a semiconductor integrated circuit, the step of patterning a semiconductor wafer coated with a resist material by exposure is an important step that affects the yield of the integrated circuit. At this time, if scratches or foreign matters are present on the mask, which is the original pattern plate, the scratches or foreign matters are transferred onto the wafer together with the pattern, which may cause a short circuit or disconnection of the produced circuit. Therefore, protection and dust protection of the mask are extremely important issues for improving productivity. In particular, in the stepper method in which the same reticle is used to repeatedly form a pattern on a single wafer, defects that occur when scratches or foreign matter exist on the reticle affect all circuits on the wafer, and therefore scratches on the reticle Adhesion of foreign matter must be avoided as much as possible.

Therefore, a pellicle covering one side or both sides of the mask has been put into practical use for the purpose of protecting the mask and preventing dust. The pellicle is generally mounted on a mask by a double-sided pressure-sensitive adhesive tape or pressure-sensitive adhesive provided on one side of a support frame made of aluminum and having a transparent thin film stretched on the other side. By mounting the pellicle, it is possible to prevent foreign matter from directly adhering to the mask surface. Even if foreign matter adheres to the pellicle film, it is out of focus of the optical system of the exposure apparatus, so that the foreign matter is not imaged on the wafer. .

However, if foreign matter adheres to the inside of the pellicle film or the support frame at the time of mounting, there is a risk that they move due to vibration or the like and directly adhere to the mask surface. for that reason,
A method has been proposed in which an adhesive layer is formed on the inner surface of a support frame (pellicle frame) for the purpose of fixing such foreign matter inside the pellicle (JP-A-60-57841, 6).
1-241756).

[0005]

Usually, the pellicle is inspected for foreign matter after manufacturing and before use. At this time, the inspection on the pellicle film is performed using an automatic inspection device, but the inspection on the inner surface of the frame is performed visually. Both the automatic inspection and the visual inspection utilize the fact that the light is scattered on the surface of the foreign matter when the light is applied.

However, conventionally, since the pressure-sensitive adhesive layer on the inner surface of the pellicle frame is formed by sticking a double-sided pressure-sensitive adhesive tape or spray coating, it is composed of a finely uneven surface, and foreign matter is present in the recessed portion. There is a problem that it is difficult to find foreign matter adhering to the surface of the pressure-sensitive adhesive during a visual inspection because it gets in and has no gloss on the surface.

The present invention has been made in view of the above problems, and an object thereof is to provide a pellicle having a pressure-sensitive adhesive layer formed on the inner surface of a frame, which makes it easy to find foreign matter during visual inspection. is there.

[0008]

Means for Solving the Problems The present inventors have made various studies in order to solve the above problems. As a result, they have found that the adhered foreign matter can be easily detected by visual inspection by making the surface of the pressure-sensitive adhesive layer a glossy surface, and completed the present invention. That is, the present invention is a pellicle characterized in that the adhesive layer formed on the inner surface of the pellicle frame has a glossy surface.

The present invention will be described in more detail below.

In the pellicle of the present invention, an adhesive layer is formed on the inner surface of the frame, and the surface is a glossy surface.
Here, the glossy surface refers to a surface that allows foreign matters having a size of 1 to 20 μm to enter and reflects light without unevenness that causes scattering when irradiated with light.

The pressure-sensitive adhesive used in the present invention is not particularly limited as long as it is liquid at room temperature. For example, it is an organic system such as an acrylic system, a rubber system, a silicon system, etc., which is dissolved or suspended in an organic solvent or water. It is preferable to use a turbid material, for example, a solution type rubber adhesive, an aqueous rubber adhesive, a solution acrylic adhesive, an aqueous acrylic adhesive, an emulsion acrylic adhesive, etc. .

The application of the pressure-sensitive adhesive is not particularly limited as long as it provides a glossy surface. For example, 1) dipping method, 2) sandwiching the pellicle frame from both sides with groove forming plates. A method of forming a groove whose bottom surface is the inner side surface of the frame, and applying an adhesive by flowing into the groove; and 3) a method of stretching the adhesive droplet on the pellicle frame with a jig and applying it. .

In the method 1), the surfaces other than the inner surface are masked with an adhesive tape or the like, the whole frame is immersed in an adhesive solution and then pulled up, and after drying, the masking agent such as the adhesive tape is peeled off to form an adhesive layer. Is the way to do it.

In the method 2), the pellicle frame is sandwiched from both sides by using groove forming plates used for forming the groove to form a groove having a bottom surface on the inner side surface of the frame, and an adhesive is poured into the groove. This is a coating method.

The method 3) is a method in which the adhesive droplets placed on the pellicle frame are stretched by a jig and applied.

After applying the pressure-sensitive adhesive, drying is performed to remove the solvent and low boiling point components. At this time, the pellicle film should not be affected by cloudiness, change in film thickness, etc.
It is preferable that the content of components having a boiling point of 170 ° C. or less is 3% or less.

The material of the pellicle frame is not particularly limited, and examples thereof include those made of aluminum, plastic, and ceramic. Those whose black surface has been treated have a foreign substance found during visual inspection. It is preferable because it is easy to do.

A pellicle film is adhered to one end surface of a pellicle frame having an adhesive layer formed on the inner surface, but the pellicle film is not particularly limited, and examples thereof include cellulose ester, polyvinyl acetal, and polycarbonate. , A single layer film of a transparent resin such as polymethylmethacrylate or polyethylene terephthalate, or an antireflection layer such as a fluororesin or MgF ₂ formed on both surfaces or one surface thereof.

A double-sided pressure-sensitive adhesive tape or pressure-sensitive adhesive is installed on the other end surface of the pellicle film to which the pellicle film is attached so as to attach the pellicle to the mask.

[0020]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 An aluminum pellicle frame (surface alumite treatment) in which the pellicle film adhesive surface, the double-sided adhesive tape installation surface and the outer surface were masked with adhesive tape was dipped in an aqueous emulsion adhesive and dried. After drying, the adhesive tape was peeled off to form an adhesive layer having a glossy surface on the inner surface of the frame. A pellicle film was adhered to one side surface of this frame, and a double-sided adhesive tape was attached to the other side surface to produce a pellicle. Fifteen foreign matters of 5 to 10 μm were adhered to the inside surface of the frame of the pellicle. 100W visual inspection illuminator (Olympus W
A total of 15 foreign substances were observable when the adhered foreign substances were visually observed by illuminating with A-LSH, voltage 12V).

Example 2 The pellicle film adhesive surface and the double-sided adhesive tape installation surface of the aluminum alloy pellicle frame whose surface was anodized were
A stainless plate having silicon rubber adhered to the surface was sandwiched and fixed from both sides to form a groove having the inner surface of the frame as the bottom surface. An aqueous emulsion acrylic pressure-sensitive adhesive was placed in this groove and poured over the entire surface to be applied. The excess adhesive was removed by suction and then dried. After drying, the stainless steel plate was removed and an adhesive layer having a glossy surface was formed on the inner surface of the frame. A pellicle film was adhered to one side surface of this frame, and a double-sided adhesive tape was attached to the other side surface to produce a pellicle. Fifteen foreign matters of 5 to 10 μm were adhered to the inside surface of the frame of the pellicle. 100W visual inspection illuminator (Olympus W
A total of 15 foreign substances were observable when the adhered foreign substances were visually observed by illuminating with A-LSH, voltage 12V).

Example 3 A square pellicle frame made of an aluminum alloy was placed upright so that one inner surface of the frame was horizontal, and two drops of an aqueous emulsion acrylic pressure-sensitive adhesive were put on one corner of the frame with a pipette. A jig having a wedge-shaped cross section and adapted to the cross-sectional shape of the frame was used to spread the coating on the entire horizontal inner surface. The frame was rotated and spread over the horizontal surface. This operation was repeated to spread the adhesive on the entire inner surface of the frame. After removing the excess pressure-sensitive adhesive, it was dried to form a uniform pressure-sensitive adhesive layer having a glossy surface on the inner surface of the frame and the tapered portion. A pellicle film and a double-sided adhesive tape were attached to this frame to produce a pellicle. 15 foreign matters of 5 to 10 μm were attached to the inner surface of the frame of the produced pellicle. When a 100 W visual inspection illumination device (WA-LSH manufactured by Olympus, voltage: 12 V) was used to visually observe the adhered foreign matter, all 15 foreign matter were confirmed.

Comparative Example A water-based emulsion adhesive was applied by a spray gun to an aluminum pellicle frame masked with an adhesive tape as in Example 1. After drying, the adhesive tape was peeled off to prepare a frame having an adhesive layer formed on the inner surface. The surface of this pressure-sensitive adhesive layer was composed of fine irregularities and had no gloss. A pellicle film and a double-sided adhesive tape were attached to this frame to produce a pellicle. 5-10μ on the inner surface of the frame of this pellicle
When 15 foreign matters of m were adhered and visually inspected with the illumination device for visual inspection under the same conditions as in Example 1, only 5 foreign matters could be confirmed.

[0025]

As is apparent from the above description, in the pellicle of the present invention, the adhesive layer on the inner surface of the frame is made to have a glossy surface, so that the foreign matter is found during the visual inspection for the adhered foreign matter inside the frame. It is easy to improve the reliability of the inspection and is effective in improving the quality of the pellicle.

Claims (1)

[Claims] 1. A pellicle comprising a pellicle frame having an adhesive layer formed on an inner surface thereof and a thin film stretched on one side of the frame, wherein the adhesive layer formed on the inner surface of the pellicle frame has a glossy surface. A pellicle characterized by having.