JP3206417B2 - Pellicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pellicle for lithography, in particular, a semiconductor device such as an LSI or an VLSI or a liquid crystal display panel. The present invention relates to an antistatic pellicle for lithography in an exposure method to be used.

[0002]

2. Description of the Related Art LS
In the manufacture of semiconductor devices such as I and VLSI or liquid crystal display panels, patterning is performed by irradiating light to a semiconductor wafer or a liquid crystal original plate. In this case, an exposure original plate such as a photomask or a reticle is used. If dust adheres to the surface, the dust absorbs or bends the light, causing the transferred pattern to be deformed, the edges to be rough, and the ground to become black and dirty. There is a problem that quality, appearance, and the like are impaired, and performance and product yield of semiconductor devices and liquid crystal display panels are reduced.

[0003] For this reason, these operations are usually performed in a clean room. However, it is difficult to always keep the original exposure plate clean even in this clean room. A method of sticking a pellicle that allows light for exposure to pass through well has been adopted.

[0004] In recent years, the line width of circuits has become finer with the increase in integration of VLSI, and in the lithography process, the exposure light source used has been changed from g-line to i-line and further to Kr.
Shorter wavelength and higher energy are being used for F excimer lasers. Along with this, for pellicles used as dustproof covers on photomasks, pellicles having high light transmittance and excellent light resistance even at short wavelengths are required, and have excellent characteristics under such use conditions. A pellicle having a pellicle film made of an amorphous fluoropolymer is used.

However, such an amorphous fluorine-containing polymer has an inferior adhesive strength with an epoxy adhesive or an acrylic adhesive which has been conventionally used as an adhesive for a pellicle film for g-line or i-line. With the conventional bonding method, sufficient bonding strength cannot be obtained, and when air blowing is performed to remove foreign substances adhering to the pellicle film, the pellicle film peels off from the bonding surface, and the reticle is contaminated. It may cause trouble and even if it does not peel completely,
The pellicle film was partially peeled off from the adhesive surface, and there was a possibility that foreign matter would enter through the gap.

As a method of bonding such an amorphous fluoropolymer, (1) the surface of the amorphous fluoropolymer is roughened by plasma dry etching such as O ₂ , CF ₄ / O ₂ , (2) a method in which the surface is modified with a short-wavelength ultraviolet ray such as a low-pressure mercury lamp or a KrF or ArF excimer laser to bond the surface;
(3) There is a method of thermal fusion bonding. However, all of these methods have problems that not only the equipment is complicated and the processing takes time, but also that the surface of the amorphous fluoropolymer is contaminated by foreign matter due to dust generation during the processing. There is.

[0007] The present invention has been made in view of the above circumstances,
In particular, it is an object of the present invention to provide a pellicle capable of holding an amorphous fluoropolymer having low adhesiveness as a pellicle film with sufficient adhesiveness.

[0008]

According to the present invention, in order to achieve the above object, an adhesive layer is formed on an upper end surface of a pellicle frame, and a pellicle film is adhered on the adhesive layer. In the pellicle attached to and stretched over the pellicle frame, an inner tapered surface is formed at an inner peripheral edge of an upper end of the pellicle frame, and the adhesive layer is applied to the inner tapered surface beyond an upper end surface of the pellicle frame. A pellicle formed in a state where the pellicle is advanced into the pellicle. In this case, the pellicle film is preferably formed of a transparent film of an amorphous polymer obtained by polymerizing a fluorine-containing monomer having a cyclic perfluoroether group alone or by polymerizing tetrafluoroethylene.

According to the present invention, since the adhesive layer is advanced to the inner tapered surface of the pellicle frame as described above, the adhesive area is increased, and the adhesive strength to a normal adhesive such as fluororesin is increased. Even if a pellicle film made of a small material is used, a higher adhesive strength can be obtained between the pellicle frame and the pellicle frame compared to the conventional method in which an adhesive layer is formed only on the top surface of the pellicle frame. The pellicle film is difficult to be detached from the pellicle frame even if it is performed. In this case, an adhesive having a relatively low adhesive strength can be used as the adhesive, so that an adhesive having excellent light resistance, but having an inferior adhesive strength can be effectively used, and the pellicle can be used. Performance can be improved.

Hereinafter, the present invention will be described in more detail. As shown in FIG. 1, the pellicle of the present invention has an adhesive layer 3 formed on an upper end surface 2 of a pellicle frame 1 and the adhesive layer 3 is formed on the adhesive layer 3. The pellicle film 4 is adhered to the pellicle film 4
When the pellicle frame 1 is stretched over the pellicle frame 1, an inner tapered surface (thread surface) is formed on the inner peripheral edge at the upper end of the pellicle frame 1.
5, the adhesive layer 3 is advanced over the upper end surface 2 to the inner tapered surface 5, and the pellicle film 4 is advanced to the inner tapered surface 5 and includes the "protruding" adhesive layer 3a. It is affixed to layer 3. In the example of FIG. 1, the outer tapered surface (thread surface) 6 is also formed on the outer peripheral edge of the upper end of the pellicle frame 1, but the adhesive layer 3 is formed.
Does not extend to the outer tapered surface 6.

Here, as the pellicle film used in the present invention, those of various materials conventionally used can be used. In the present invention, in particular, the pellicle film has a sufficient adhesive strength to ordinary adhesives. Can be effectively used. Examples of such an amorphous fluorine-containing polymer include CYTOP (trade name, manufactured by Asahi Glass Co., Ltd.) and Teflon AF (trade name, manufactured by Dupont Co., Ltd.).

Further, as the adhesive for the pellicle film,
Conventionally used ones can be used. For example, acrylic resin adhesives, epoxy resin adhesives, silicone resin adhesives, fluorine-containing silicone adhesives and the like can be suitably used.

The material of the pellicle frame is SU.
S, a metal such as an aluminum alloy, a resin such as polyacetal, polycarbonate, PMMA, and acrylic resin, and a material such as blue plate glass can be used.

The shape of the pellicle frame can be a known shape, but it is necessary that the pellicle frame has the tapered surface (thread surface) 5 at least at the inner peripheral edge of the upper end as described above. In this case, the width W of the tapered surface (see FIG. 2)
Is not necessarily limited, but is preferably about 0.05 to 0.5 mm, particularly 0.1 to 0.35 mm. If the width W is too small, the adhesive strength is poor. When inspecting the pellicle film surface using a surface foreign matter measuring device or the like, light may be scattered at the tapered surface portion and adversely affect the measurement. Further, the inclination angle θ of the tapered surface is preferably 30 to 60 °, particularly preferably 33 to 55 °. If the inclination angle θ is too small, the adhesive may penetrate further inside the frame taper surface, and may contaminate the pellicle film or block light for exposure. If the inclination angle θ is too large, the adhesive may fall down to the inner surface of the pellicle frame, and the adhesive strength may not be improved.

A known method can be used to stretch the pellicle film on the pellicle frame using the above adhesive.
In this case, in the present invention, the adhesive layer is formed so as to advance to the inner tapered surface as described above. Specifically, the adhesive is applied to the entire upper end surface and the inner tapered surface so as to protrude to almost the center in the width direction. At this time, if the adhesive layer protrudes to the outer tapered surface, there is a possibility that the cutting will be an obstacle in cutting the pellicle film. Therefore, the adhesive is applied so as not to protrude to the outer tapered surface. The method of applying the adhesive includes brushing, spraying,
Although an automatic dispenser method is used, it is preferable to use an automatic dispenser using an XY stage as a coating method, in particular, in order to accurately protrude the inner tapered surface. As another method, an appropriate amount of adhesive is applied to the upper end surface of the pellicle frame, and when bonding the pellicle film, the adhesive is pressurized by an appropriate load, and the adhesive layer is formed on the inner tapered surface substantially in the width direction. A method of sticking out the pellicle film by sticking out the pellicle film may be adopted.

In this case, the pellicle film is formed by devising a coating method or pressing the adhesive layer so that the upper side of the inner peripheral edge of the adhesive layer projects inward as shown in FIG. It is preferable that the air is applied from the inside of the pellicle film by, for example, air blow, and even if a force such as peeling the pellicle film from the frame is applied, the adhesive layer is deformed with the pellicle film. The inwardly protruding portion is also deformed at the same time, and generates an adhesive force sufficiently larger than the force for peeling the pellicle film from the adhesive surface, thereby reliably preventing the pellicle film from being peeled from the pellicle frame.

[0017]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1 Teflon AF1600 (trade name, manufactured by DuPont, USA) was dissolved in a fluorinated solvent Fluorinert FC-75 (trade name, manufactured by 3M, USA) to prepare a solution having a concentration of 8%. Next, this solution was applied to a mirror-polished silicon substrate surface having a diameter of 250 mm and a thickness of 600 μm using a spin coater, and the thickness of the film was reduced to 0.1 mm.
An 8 μm transparent film was formed.

On this film, an outer dimension of 200 mm × 200 mm ×
A frame having a width of 5 mm and a thickness of 5 mm was adhered using an epoxy-based adhesive Aralditrapid (trade name, manufactured by Showa Polymer Co., Ltd.). The adhesive was applied using an automatic dispenser using a YXZ stage. The adhesive was applied to the half of the inner thread surface part of the adhesive application upper end surface, applied and bonded, and then peeled in water. .

Next, frame outer dimensions 100 mm × 100 m
An aluminum alloy frame having a size of mx 5 mm in width and a frame thickness of 4 mm was bonded to the surface of Teflon AF1600 formed by using an epoxy-based adhesive Aralditrapid (trade name, manufactured by Showa Polymer Co., Ltd.). An automatic dispenser using a YXZ stage is used to apply the adhesive, and the inner tapered surface (width 0.2 mm,
The adhesive was applied to one half of the portion (tilt angle: 45 °) so as to protrude and adhered. The cross-sectional shape of the applied adhesive was the same as in FIG. The two frames were attached to a fixing jig with the adhesive surface of the pellicle frame facing upward and fixed so as not to be relatively displaced.

As another apparatus for cutting the membrane, a stainless steel cutter (0.25 m in thickness) was attached to a scalar robot.
m). While moving the cutter along the periphery of the adhesive portion of the pellicle frame, unnecessary film portions outside the pellicle frame were cut and removed. 20 samples were produced in the same manner as above.

With respect to the completed pellicle, the adhesive strength of the pellicle film was measured. An autograph (manufactured by Shimadzu Corporation) was used for the measurement. The pellicle film was cut to a width of 5 cm while leaving the frame portion, the film side was attached to the upper chucking portion, and the frame was attached to the lower chucking portion.
This was pulled at a speed of 100 mm per minute,
When the peel strength of the adhesive was measured for each piece, the average was 3
A peel strength of 0 g / cm was obtained.

Comparative Example 1 The procedure of Example 1 was repeated except that the adhesive was applied only to the upper end face without protruding to the inner tapered surface of the frame. The pellicle film was adhered.

When the peel strength of the adhesive was measured for the 20 completed pellicle samples in the same manner as in Example 1, an average peel strength of only 0.5 g / cm was obtained.

Embodiment 2 Cytop CTX809SP
2 (trade name, manufactured by Asahi Glass Co., Ltd.)
LV. 180 (trade name, manufactured by Asahi Glass Co., Ltd.)
A 3% strength solution was prepared. Next, this solution was added to a solution having a diameter of 25.
0 mm, 600 μm thick mirror-polished silicon substrate surface is applied using a spin coater, the film thickness is 0.8 μm
m of transparent film was formed.

On this film, an outer dimension of 200 mm × 200 mm ×
A frame having a width of 5 mm and a thickness of 5 mm was adhered using an epoxy-based adhesive Aralditrapid (trade name, manufactured by Showa Polymer Co., Ltd.). The adhesive was applied using an automatic dispenser using a YXZ stage. The adhesive was applied to the half of the inner thread surface part of the adhesive application upper end surface, applied and bonded, and then peeled in water. .

Next, the outer dimensions of the frame are 100 mm × 100 m.
A frame made of an aluminum alloy having a size of mx 5 mm and a frame thickness of 4 mm was adhered to the surface of a CYTOP film formed by using an epoxy adhesive Aralditrapid (trade name, manufactured by Showa Polymer Co., Ltd.). An automatic dispenser using a YXZ stage was used to apply the adhesive, and the inner tapered surface (width 0.2 mm, inclination angle 45
°) The adhesive was applied to one half of the part by sticking out and adhered. The cross-sectional shape of the applied adhesive was the same as in FIG.
The two frames were attached to a fixing jig with the adhesive surface of the pellicle frame facing upward and fixed so as not to be relatively displaced.

As another apparatus for cutting the membrane, a scalar robot was used to attach a stainless steel cutter (0.25 m thick).
m). While moving the cutter along the periphery of the adhesive portion of the pellicle frame, unnecessary film portions outside the pellicle frame were cut and removed. 20 samples were produced in the same manner as above.

With respect to the completed pellicle, the adhesive strength of the pellicle film was measured. An autograph (manufactured by Shimadzu Corporation) was used for measurement. The pellicle film was cut to a width of 5 cm while leaving the frame portion, the film side was attached to the upper chucking portion, and the frame was attached to the lower chucking portion.
This was pulled at a speed of 100 mm per minute,
When the peel strength of the adhesive was measured for each piece, the average was 3
A peel strength of 0 g / cm was obtained.

Comparative Example 2 The same operation as in Example 2 was carried out except that the adhesive was applied only to the upper end face without protruding to the inner tapered surface of the frame. The pellicle film was adhered.

When the peel strength of the adhesive was measured for the 20 completed pellicle samples in the same manner as in Example 2, an average peel strength of only 0.5 g / cm was obtained.

[0032]

According to the pellicle of the present invention, the adhesive strength between the pellicle film and the adhesive layer is large, and the pellicle film shows sufficient adhesiveness to treatment such as air blow. In particular, the pellicle film is made of an amorphous fluoropolymer. It is particularly suitable.

[Brief description of the drawings]

FIG. 1 is a partially enlarged sectional view showing a pellicle according to one embodiment of the present invention.

FIG. 2 is a partially omitted cross-sectional view of the pellicle of the same example.

FIG. 3 is a partially enlarged sectional view of a conventional pellicle.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 pellicle frame 2 upper end surface 3 adhesive layer 4 pellicle film 5 inner tapered surface 6 outer tapered surface

Claims (2)

(57) [Claims] 1. An adhesive layer (3) is formed on an upper end surface of a pellicle frame (1), and a pellicle film (4) is adhered on the adhesive layer (3) to form the pellicle frame (1). In the pellicle, the inner surface of the upper edge of the pellicle frame (1) is formed with an inner tapered surface (5), and the adhesive layer (3) is attached to the upper surface of the pellicle frame (1). Beyond the inner tapered surface (5)
A pellicle formed in a state where the pellicle has advanced into the pellicle. 2. The pellicle according to claim 1, wherein the pellicle film is a transparent film of an amorphous polymer obtained by polymerizing a fluorine-containing monomer having a cyclic perfluoroether group alone or by polymerizing tetrafluoroethylene.