JP2003307832A - Pellicle and pellicle wearing photomask - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pellicle which reduces an inclination proper to a pellicle and a pellicle attached photomask. <P>SOLUTION: Spacers 26 such as glass beads are mixed into an adhesive 24 for bonding a pellicle frame 12 of quartz glass or the like and a pellicle plate 11 of synthetic quartz to each other and into an agglutinant 25 for sticking the pellicle frame 12 and a photomask 13 to each other. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is used in the photolithography process of semiconductor processing, and more particularly in the wavelength range 22.
The present invention relates to a pellicle suitable for exposure using light of 0 nm or less and a pellicle-mounted photomask.

[0002]

2. Description of the Related Art In a photolithography process of a semiconductor process, a semiconductor wafer coated with a photoresist is projected and exposed to form a pattern. If the photomask used at this time has scratches or foreign matter, it may cause pattern defects (circuit short circuit or disconnection, etc.) during exposure. Therefore, in order to prevent foreign matter from adhering to the photomask pattern surface, it is effective to mount a pellicle on one side or both sides of the photomask.

A cross-sectional view of a conventional pellicle is shown in FIG. The conventional pellicle includes a pellicle frame 32 made of aluminum or the like and a pellicle film 31 made of nitrocellulose or fluororesin having a thickness of several nm to several μm such as an organic resin film.
The pellicle film 31 is attached to one opening surface of the frame-shaped pellicle frame 32 with an adhesive 34. The pellicle includes a pellicle frame 32 and a photomask 33.
The adhesive 35 is interposed between the photomask 33 and the photomask 33, and the photomask 33 is fixed and used so as to cover the pattern surface.

In recent years, exposure using light having a wavelength of 220 nm or less has been studied in response to demands for pattern miniaturization and high density. However, the pellicle using the above-mentioned organic resin film or the like has low durability because the organic content of the organic resin film is decomposed when short-wavelength exposure light is used to improve the exposure resolution. Therefore, in a short wavelength exposure system, the use of a pellicle plate made of quartz glass as a pellicle film has been studied. This quartz glass is obtained by, for example, reacting a silicon source and an oxygen source in a gas phase to grow a porous body made of silicon oxide called soot, and sintering the porous body to obtain substantially only silicon oxide. It is a synthetic quartz glass consisting of.

However, when the pellicle plate made of quartz glass is adhered to the upper end surface of the conventional pellicle frame to manufacture the pellicle, the pellicle plate has parallelism and flatness of the upper and lower surfaces of the pellicle plate and the pellicle frame is ensured. Must be kept in mind.

That is, the pellicle plate needs to have a thickness of about 0.01 to 2 mm in order to secure practical strength. However, if there is variation in the thickness of the pellicle plate, the optical path of refracted light changes, and thus the pellicle plate is transferred. The pattern is out of position, and good lithography cannot be performed. For this reason, the parallelism of the upper and lower surfaces allowed for the pellicle plate is about 0.1 μm / 50 mm.

If the parallelism between the two surfaces, which are the pellicle plate fixed on the upper and lower surfaces of the frame and the mask surface, is poor, the position of the transfer pattern may shift. Also, since the pellicle plate is used as a pellicle by adhering it to the pellicle frame, if the flatness of this adhering surface is not accurate, the pellicle plate after adhering will be corrected to the shape of the upper surface of the pellicle frame. Therefore, there is a possibility that an optical defect such as bending due to bending or an increase in birefringence due to the correction force may occur. Furthermore, if the flatness of the lower surface of the pellicle frame is poor, the frame itself may be distorted or warped when it is bonded to the photomask surface, and the pellicle plate may be warped. For this reason,
The flatness of each surface of the pellicle frame that is bonded to each other is 1 μm or less, and the parallelism between the upper and lower surfaces is 2 at the same time.
It is required to be less than μm. In order to secure the flatness of the upper limit surface of the pellicle frame, it is preferable to use quartz glass as the material of the pellicle frame.

However, even if the parallelism of the pellicle plate and the flatness of the pellicle plate and the pellicle frame are within the above ranges, it may not be possible to obtain a pellicle with no displacement of the transfer pattern.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to provide a pellicle and a pellicle-mounted photomask in which the positional deviation of the transfer pattern is small.

[0010]

DISCLOSURE OF THE INVENTION As a result of investigations, the inventors of the present invention have found variations in the thickness of the adhesive after the pellicle plate and the pellicle frame are bonded, and the thickness of the adhesive after the pellicle frame and the photomask are bonded. Finding that the parallelism between the pellicle plate and the mask is also affected by variations,
The present invention has been completed.

That is, the present invention is, firstly, a pellicle provided with a frame-shaped pellicle frame and a pellicle plate adhered to one opening of the pellicle frame, wherein the pellicle frame and the pellicle plate are made of quartz glass. And a pellicle characterized in that an adhesive layer including a spacer is interposed between the pellicle plate and the pellicle frame.

Secondly, it is provided with a frame-shaped pellicle frame and a pellicle plate adhered to one opening of the pellicle frame, and the pellicle frame and the pellicle plate are made of quartz glass, and the pellicle plate of the pellicle frame is mounted. And a photomask attached to the opening on the side opposite to that of the pellicle, wherein the pellicle has a bonding layer including a spacer interposed between the pellicle frame and the photomask. Provide a wearing photomask.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view and a plan view of a pellicle-mounted photomask showing an example of a pellicle and a pellicle-mounted photomask according to an embodiment of the present invention. In the opening on the upper surface of the pellicle frame 12, the pellicle plate 11 made of quartz glass processed to have a plate thickness of about 0.01 to 2 mm is attached to the adhesive 1
The pellicle frame 12 and the pellicle plate 11 form a pellicle. As shown in FIG. 1, the pellicle is used by being attached to the photomask 13 with an adhesive 15.

FIG. 2 is an enlarged conceptual diagram of FIG. The adhesive layer 14 interposed between the pellicle frame 12 and the pellicle plate 11 includes an adhesive 24 and a spacer 26. Further, the adhesive layer 15 interposed between the pellicle frame 12 and the photomask 13 also includes the adhesive 25 and the spacer 26 in the same manner.

Quartz glass is used as the material of the pellicle plate 11 of the present invention, and when it is used especially for vacuum ultraviolet rays such as F ₂ laser, the pellicle plate 11 is made of synthetic quartz glass having high durability against vacuum ultraviolet rays. preferable. Further, in order to improve the light transmittance, it is preferable to apply an antireflection film on one surface or both surfaces of the pellicle plate 11.

The pellicle frame 12 uses quartz glass as a material. The quartz glass may be fused quartz glass or synthetic quartz glass. This way, the pellicle frame 1
The residual stress due to the processing of 2 can be reduced as much as possible, and the occurrence of distortion of the photomask 13 after the pellicle is mounted on the photomask 13 can be reduced. Further, quartz glass has the advantages of higher rigidity and lower expansion coefficient than conventional aluminum. To reduce the tilt of the pellicle itself,
It is preferable to improve the parallelism and flatness of the pellicle frame 12 and the pellicle plate 11 and reduce the stress and strain caused by the adhesion between the two.

As the substrate used in the photomask with a pellicle of the present invention, glass substrates such as soda lime silicate glass, low expansion glass and synthetic quartz glass can be used. However, since high parallelism is required, the expansion coefficient is low. Synthetic quartz glass is commonly used.

The adhesive used to bond the pellicle plate 11 to the pellicle frame 12 is a thermosetting adhesive such as epoxy, acrylic, silicone, or fluororesin,
Alternatively, an ultraviolet curable adhesive or the like can be used. As an adhesive used for attaching the pellicle to the photomask 13, it is preferable to use an adhesive such as an epoxy type, an acrylic type, a silicone type, or a fluororesin type in consideration of the convenience of later removal, but the pellicle plate An adhesive that bonds the pellicle frame with the pellicle frame can also be used.

In the present invention, the spacer 2 is provided in the adhesive layer.
By mixing 6 with each other, variation in thickness of the adhesive layer 14 after adhesion is reduced, and stress and strain of the pellicle plate are reduced. Further, in order to reduce the inclination of the photomask 13 having the pellicle attached thereto, similarly, the spacer 26 is mixed in the adhesive layer to reduce the thickness variation of the adhesive layer 15 and reduce the stress and stress of the pellicle plate. Reduce strain.

As the spacer 26 mixed in the adhesive layer 14 and the adhesive layer 15, glass beads are used, for example. The average particle size of the glass beads is preferably 0.5 to 10 μm, and the standard deviation of the particle size distribution of the glass beads is preferably 0.2 μm or less, and it is particularly desirable to use spherical fine particles. The spacer 26 is preferably made of a material having substantially the same thermal expansion coefficient as that of the pecryl plate 11 and the photomask 13, and is preferably made of synthetic quartz glass.

In the method of manufacturing a pellicle of the present invention, a block of synthetic quartz glass is sliced, chamfered, and then lapping and polishing are performed by a double-side polishing machine so that the flatness of each of the upper surface and the lower surface of the pellicle plate 11 is reduced. The allowable parallelism between the upper and lower surfaces of the pellicle plate 11 is 1 μm or less and 2 μm or less. The flatness of the upper surface and the lower surface of the pellicle frame 12 is 1 μm or less, and the parallelism of the upper and lower surfaces of the pellicle frame 12 is 2 μm or less. Next, the spacer 26 is mixed with the adhesive 25. At that time, the content of the spacers 26 in the adhesive layer 14 is preferably in the range of 0.1 to 50% in terms of 100 mass percentage, which does not hinder the adhesive strength by effectively acting as spacers. After applying the above-mentioned adhesive 24 to the bonding surface of the pellicle plate 11 or the pellicle frame 12, the two are overlapped and pressed,
The adhesive 24 is cured by thermocompression bonding or ultraviolet curing,
The pellicle of the present invention is manufactured.

In the pellicle manufactured by the above-described method, the adhesive 25 mixed with the spacer 26 is applied to the adhesive surfaces of the pellicle frame 12 and the photomask 13 in the same manner as the adhesive 24 described above, and then the pattern surface of the photomask 13 is applied. The pellicle-mounted photomask of the present invention is manufactured by pressing and fixing so as to cover the.

[0023]

EXAMPLE First, a block of synthetic quartz glass obtained by a known method is sliced to have a diameter of 200 mm and a thickness of 1.2.
A blank for 0 mm pellicle plate was obtained. After chamfering the raw plate, lapping and polishing were performed by a double-side polishing machine to obtain a synthetic quartz glass substrate having a diameter of 200 mm and a thickness of 0.80 mm. When the optical flatness and parallelism of the substrate were measured, the flatness was 2 μm or less and the parallelism was 0.5 μm or less. An antireflection film was formed on both surfaces of the substrate using a vacuum vapor deposition machine to prepare a pellicle plate.

Similarly, for the pellicle frame, a block of synthetic quartz glass obtained by a known method was sliced to obtain a blank plate having a length of 152 mm × width of 152 mm × thickness of 5.2 mm. The base plate was chamfered and lapped and polished by a double-side polishing machine to obtain a synthetic quartz glass substrate having a thickness of 5.0 mm. When the optical flatness and parallelism of the substrate were measured, the flatness was 0.5 μm or less and the parallelism was 1 μm or less.

The substrate is carved using an end mill,
External size Vertical 149 mm x Horizontal 122 mm, Internal size Vertical 145 mm x
A pellicle frame having a rectangular frame having a width of 118 mm and each corner having a radius of 5 mm was manufactured. At this time,
Since the processing in the thickness direction is not performed, the thickness is 5.0 mm.

Next, to 50 g of an ultraviolet curable adhesive (manufactured by ThreeBond, trade name 3052B), glass beads (manufactured by Catalysts & Chemicals Co., Ltd., trade name: Shin-Gama-SW-)
2.0) 1 g was added and the above-mentioned pellicle frame to which the pellicle plate had already been bonded was bonded. Then, the pellicle plate was fused with a laser cutting machine according to the outer shape of the pellicle frame.

Further, a blank for a photomask having synthetic quartz obtained as a base material by a known method was prepared. The optical flatness of this blank was measured and found to be 0.45.
was μm.

The above pellicle was adhered onto this blank using the above adhesive to produce a pellicle-mounted photomask.

The parallelism between the pellicle plate and the photomask surface of the above-described pellicle-mounted photomask is determined by OMRON Z30.
When measured with a No. 0 measuring instrument, a result of 0.8 μm was obtained.

The apparatus and materials used in the above embodiments are not limited, and any type may be used as long as they have equivalent performance and purpose.

[0031]

According to the present invention, it is possible to obtain a pellicle and a pellicle-mounting photomask in which the transfer pattern is less displaced.

[Brief description of drawings]

FIG. 1 is a plan view and a sectional view showing an embodiment of the present invention.

FIG. 2 is a partially enlarged view of the cross-sectional view of FIG.

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

[Explanation of symbols]

11: Pellicle board 12: Pellicle frame 13: Photo mask 14: Adhesive layer 15: Adhesive layer 24: Adhesive layer 25: Adhesive layer 26: Spacer 31: Pellicle film 32: Pellicle frame 33: Photomask 34: Adhesive layer 35: Adhesive layer

Claims (6)

[Claims] 1. A pellicle comprising a frame-shaped pellicle frame and a pellicle plate adhered to one opening of the pellicle frame, wherein the pellicle frame and the pellicle plate are made of quartz glass, and the pellicle plate and the pellicle frame are provided. A pellicle having an adhesive layer including a spacer interposed therebetween. 2. A pellicle frame having a frame shape and a pellicle plate bonded to one opening of the pellicle frame,
A pellicle mounting photomask, comprising a pellicle frame and a pellicle plate made of quartz glass, and a photomask mounted in an opening on the opposite side of the pellicle plate mounted on the pellicle frame. A pellicle-mounted photomask, wherein an adhesive layer including a spacer is interposed between the photomask and the photomask. 3. The pellicle according to claim 1, wherein the spacers contained in the adhesive layer are glass beads. 4. The pellicle-mounted photomask according to claim 2, wherein the spacer contained in the adhesive layer is glass beads. 5. The pellicle according to claim 1, wherein the flatness of each surface of the pellicle plate and the pellicle frame which are bonded to each other is 1 μm or less. 6. The pellicle-mounted photomask according to claim 2, wherein the parallelism between the pellicle plate and the photomask surface is 2 μm or less.