HK1192329B - Pellicle for photolithography - Google Patents

Description

Pellicle for lithography

The present application is a divisional application of an invention patent application entitled "protective film assembly for lithography", application No. 201010100202.5, filed on 25.01.2010 by shin-Etsu chemical industries, Ltd.

Technical Field

The present invention relates to a pellicle for lithography used as a dust-proof mask for lithography in the manufacture of semiconductor devices such as LSI and ultra-LSI, and liquid crystal display panels.

Background

In the manufacturing process of semiconductor devices such as LSI and super LSI, or products such as liquid crystal display panels, a semiconductor wafer or a liquid crystal master plate is irradiated with light to form a pattern, and if dust adheres to an exposure master plate (mask for lithography) used at this time, the dust absorbs the light to reflect the light, thereby deforming the transferred pattern and roughening the edge, and also causing the substrate to be stained and blackened to deteriorate the size, quality, appearance, and the like.

Therefore, these operations are usually performed in a clean room, but even in a clean room, it is difficult to keep the exposure original plate clean, and therefore, a pellicle assembly formed by attaching a pellicle film having good light transmittance to a pellicle assembly frame is used as a dust-proof device by attaching a pellicle film to the surface of the exposure original plate. In this case, since the foreign matter is not directly attached to the surface of the exposure original plate but is attached to the protective film, the foreign matter on the protective film does not affect the transfer if the pattern of the exposure original plate is brought into focus during photolithography.

The basic structure of the protective film component is composed of a protective film component frame and a protective film; the protective film is composed of substances such as nitrocellulose, cellulose acetate, fluorine-based polymers and the like, is transparent, and has good light transmittance for exposure light; the protective film component frame is made of aluminum alloy, stainless steel, polyethylene and other materials which are treated by black aluminum oxide and meet Japanese Industrial Standards (JIS) such as A7075, A6061, A5052 and the like; coating a solvent for a pellicle film on the top of a pellicle frame, and bonding the pellicle film to the top of the pellicle frame by air-drying (see patent document 1), or bonding with an adhesive such as an acrylic resin, an epoxy resin, or a fluororesin (see patent documents 2 and 3); then, in order to lay the exposure original plate on the lower portion of the pellicle frame, an adhesive layer made of polybutylene resin, polyvinyl acetate resin, acrylic resin, silicone resin, or the like, and a reticle adhesive protection pad for protecting the adhesive layer are provided.

When the pellicle is attached to the exposure original plate, a closed space is formed inside the pellicle. At this time, since the protective film has no air permeability, if the temperature changes, the gas in the closed space expands or contracts, and the protective film is made to swell upward or to sag downward. In order to prevent this problem, a vent hole is provided in the pellicle frame (see patent document 4). Patent document 4 discloses, as shown in fig. 8, a pellicle frame 12 provided with a vent hole 11; and a pellicle frame 13 coated with an adhesive 14, the adhesive 14 being capable of capturing dust which invades into the sealed space of the pellicle or which is present or generated in the sealed space of the pellicle.

In addition, there is also an example in which no adhesive is used inside the pellicle assembly, and only the frame of the pellicle assembly is provided with vent holes (see fig. 9).

However, the pellicle provided with one or more vent holes is poor in ventilation efficiency, and if the air pressure in the closed space inside the pellicle is varied, for example, if the air pressure in the mask environment accompanying exposure is not varied so much, smooth ventilation is not possible, and organic or inorganic gases generated from members of the pellicle are separated from the members of the pellicle during exposure or mask storage with irradiation of ultraviolet rays (i-line, g-line, KrF laser, ArF laser, F2 laser, etc.) in the photolithography step, and during exposure or mask storage, and are generated and retained in the closed space formed by the pellicle and the mask to form gaseous substances, and ammonia, a cyanide compound, or other hydrocarbon compounds present in the environment under the ultraviolet rays during exposure undergo a photochemical reaction, and substances such as ammonium sulfate are generated as misty substances or fine particles, which are called mist, it is quite difficult to solve these problems.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent application laid-open No. Sho 58-219023

[ patent document 2] specification of U.S. Pat. No. 4861402

[ patent document 3] Japanese examined patent publication No. 63-27707

[ patent document 4] Japanese patent application laid-open No. 3-166545

The pellicle covers a pattern region formed on the surface of the mask substrate. The protective film assembly is a member provided for preventing foreign matters from adhering to the mask substrate, so that the pattern region can be isolated from the outside of the protective film assembly, and dust outside the protective film assembly can be prevented from adhering to the surface of the pattern.

In recent years, the layout rule of LSIs has been reduced to 0.25 μm or less, and shorter wavelengths of exposure light sources have been used, that is, laser light such as KrF excimer laser (248 nm), ArF excimer laser (193 nm) or F2 laser (157 nm) has been used from g-line (436 nm) and I-line (365 nm) of mercury lamps which have been the mainstream. As described above, the exposure light has a shorter wavelength, and the energy of the exposure light is naturally higher. When light of high energy is used, the possibility that a gaseous substance existing in the exposure environment reacts to generate a reactive substance on the mask substrate becomes higher than that of light of a conventional wavelength.

Then, we take several countermeasures, such as: minimize the gas-like substance in the clean room, clean the reticle completely, or remove the gas-emitting substance from the constituent material of the pellicle assembly. In particular, since the pellicle is used by being directly attached to the mask substrate, the gas diffusion rate of the constituent material of the pellicle, that is, the material of the reticle adhesive, the film adhesive, the inner wall coating agent and the like made of an organic material is preferably reduced to improve the situation. However, even if the mask is cleaned again or the gas emission characteristics of the material constituting the pellicle assembly are reduced, it is impossible to completely prevent the formation of mist-like foreign matter called "mist" on the mask substrate, which causes a reduction in the yield of semiconductor products.

Disclosure of Invention

[ problems to be solved by the invention ]

In view of the above, the problem to be solved by the present invention is to reduce as much as possible the substances causing the trouble in the exposure in the sealed space between the pellicle and the mask from the inner space of the pellicle.

[ means for solving problems ]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a gas generated from a member constituting a pellicle assembly escapes from the pellicle assembly member under an exposure environment, remains in a sealed space between the pellicle assembly and a mask, and when the gas is irradiated with short-wavelength ultraviolet rays during exposure, mist such as ammonium sulfate or hydrocarbon compounds is generated.

Accordingly, the present inventors have proposed a pellicle in which gas generated from the constituent elements of the pellicle is less likely to stay in the internal space of the pellicle, and have completed a pellicle in which the generation rate of mist is low even in an exposure environment of short ultraviolet light.

That is, the pellicle for lithography according to the present invention is characterized in that a plurality of vent holes are provided in a pellicle frame for lithography, and the vent holes are covered with a dust-proof filter, wherein the pellicle frame for lithography has a thickness of 2mm, a plurality of vent holes are provided at least on one side, a countersink having a depth of 1mm is provided across the plurality of vent holes on at least one side, and a wall surface of the countersink is formed into a tapered shape. At least one vent hole and a spot facing portion are provided on each of the sides other than the at least one side, an angle between an inclined surface formed by the tapered shape and an outer side surface of the face frame is larger than 90 degrees and smaller than 180 degrees, the spot facing portion is circular or elliptical, and the spot facing portion can straddle the plurality of vent holes.

[ efficacy against the prior art ]

In the present invention, the vent hole provided on the outer surface of the pellicle frame and the filter covering the vent hole are disposed at the bottom of the recess provided on the outer surface of the pellicle frame by spot facing, the wall surface of the recess is formed into a tapered shape, and the stage of the stepper or scanner is moved at a high speed, so that the outside air can be efficiently introduced and discharged, and further, as shown in fig. 7, the air staying in the sealed space formed by the pellicle can be efficiently discharged, and the air is less likely to stagnate inside. Therefore, it is possible to cope with the progress of shorter wavelength by the effect of making the mask less likely to generate mist.

And the interval between the vent holes can be shortened by arranging the spot facing processing part across the plurality of vent holes.

Drawings

Fig. 1 is an explanatory view showing one embodiment of a pellicle of the present invention.

Fig. 2 (a), (b), and (c) are perspective explanatory views showing various examples of the partially flattened portion provided around the vent hole of the pellicle frame of the present invention, wherein (a) the partially flattened portion has an elliptical shape, (b) the partially flattened portion has a circular shape, and (c) the partially flattened portion has a "continuous shape" including a plurality of vent holes 2 in common.

FIG. 3 is an explanatory diagram showing the definition of the taper angle of the partial flattening portion according to the present invention.

Fig. 4 is a view illustrating an example of arrangement of vent holes provided in a frame of a pellicle assembly of the present invention.

Fig. 5 is a view illustrating another example of the arrangement of the vent holes provided in the frame of the pellicle assembly of the present invention.

Fig. 6 is a view illustrating another example of the arrangement of the vent holes provided in the frame of the pellicle assembly of the present invention.

Fig. 7 is an explanatory view showing an example of the flow of the outside air in the pellicle attached to the mask substrate when the scanning stage is moved.

FIG. 8 shows an embodiment of a conventional pellicle provided with a vent hole and an adhesive layer.

FIG. 9 shows an embodiment of a conventional pellicle in which a frame of the pellicle is provided with vent holes.

Description of the reference numerals

1-pellicle frame

2-air vents

3-Filter (for dust prevention)

4-spot facing

5 to the outer side (of the pellicle assembly frame 1)

6-arrow mark

11-air vents

12-frame edge of protective film component

13-frame edge of protective film component

14-adhesive

15-filter

Detailed Description

The invention is a pellicle for lithography, characterized in that: the installed protective film assembly frame is provided with a mechanism for passively ventilating the interior of the protective film assembly.

The present invention is described in detail below with reference to the accompanying drawings.

In the pellicle of the present invention, basically, as in the conventional art, a pellicle frame is coated with a pellicle film bonding adhesive on the upper end face thereof and a pellicle film is applied thereon, and in this case, a reticle bonding adhesive is usually applied on the lower end face thereof, and a gasket is bonded to the lower end face of the reticle bonding adhesive in a peelable manner.

In this case, the size of the pellicle member is the same as that of a general pellicle, such as a pellicle for semiconductor lithography, a pellicle for a photolithography step in the manufacture of large-sized liquid crystal display panels, etc., and the conventional materials can be used. In more detail, the type of the protective film is not particularly limited, and for example, amorphous fluoropolymers for excimer laser and the like can be used. Amorphous fluoropolymers, for example: cytop (trade name manufactured by Asahi glass corporation), Teflon AF (trade name manufactured by Du Pont), and the like. When the protective film is made of these polymers, they may be dissolved in a solvent before use, for example, they may be properly dissolved in a fluorine solvent.

The base material of the pellicle frame used in the present invention may be an aluminum alloy base material used in the past, and it is preferable to use a base material having a standard such as JIS a7075, JIS a6061, and JIS a5052, and even if a material other than the aluminum alloy base material, such as resin or glass, is used, the material is not particularly limited as long as it has sufficient strength as the pellicle frame.

One of the features of the pellicle assembly of the present invention is that vent holes are provided in the pellicle assembly frame, filters are provided over the vent holes, and "locally flattened" portions are formed around the portions where the filters are provided. An example of such a typical pellicle assembly is shown in figure 1.

In fig. 1, reference numeral 1 denotes a pellicle frame, and a vent hole 2 is provided in the pellicle frame 1, and a dust-proof filter 3 is covered on the vent hole 2. The spot facing 4 is provided at an outer portion of the pellicle assembly frame 1.

The portion where the vent hole is provided is countersunk deeper than the filter thickness by a hole size larger than the vent hole, and there is no particular limitation as long as the portion is not dug more than the thickness of the pellicle assembly frame, but an angle of more than 90 ° is still necessary for the wall surface of the countersunk portion. An angle smaller than 90 ° forms a shape that blocks the vent hole, and conversely, a larger angle increases the flow rate of the outside air flowing into the vent hole. However, when the angle is larger than 180 degrees, the gas flow force is disturbed, and the benefit of increasing the gas flow rate cannot be obtained. The outer shape of the spot facing portion is not particularly limited as long as the flow rate of the outside air can be efficiently introduced, and for example, an elliptical shape [ fig. 2 (a) ] or a circular shape [ fig. 2 (b) ] may be adopted, and a "continuous shape" extending over the plurality of vent holes 2 [ fig. 2 (c) ] may be further adopted.

The local flat part is cut out inward from the outer side surface 5 of the pellicle assembly frame 1 in a tapered shape as shown in fig. 3, and when the local flat part taper angle is determined, the local flat part taper angle is larger than 90 degrees and smaller than 180 degrees as shown by an arrow 6.

At least more than one vent hole is respectively arranged on four side surfaces (edges) of the protective film component frame. The size and shape of the vent hole are not particularly limited, but the size and shape should be selected according to the mesh size and filtration area of the filter provided in the vent hole, or the ventilation amount determined from these parameters. In addition, the vent holes are provided to ventilate the inside and outside of the pellicle membrane assembly, so that polluted air in the pellicle membrane assembly does not remain, and therefore, the vent holes are preferably arranged so that each corner in the pellicle membrane assembly can be ventilated as much as possible.

The ventilation holes can be disposed near the four corners of the frame of the pellicle as well as near the center of the frame, etc. as preferred embodiments. The number of the vent holes provided in the frame of the pellicle assembly may be appropriately changed in consideration of exposure conditions, use time, and even cost.

The results shown in table 1 were obtained through investigation and experiment concerning the relationship between the number and arrangement of the vent holes in the four sides of the pellicle assembly frame and the generation of mist.

That is, the exposure amount of ArF excimer laser is 500J/cm in various combinations by using an A7075-T651 frame made of an aluminum alloy having an outer dimension of 149mm × 122mm × 5.8.8 mm and a frame thickness of 2mm, and setting the number of vent holes provided in each of the long sides and each of the short sides facing each other to be the same or different, or setting the number of vent holes in each of the long sides and the short sides to be the same or different, and setting the exposure amount to ArF excimer laser to be 500J/cm²The experiment was confirmed by checking "whether mist was produced". The laser light scattering foreign matter inspection device is used to inspect whether the mist is generated.

Fig. 4 to 6 show some embodiments of the arrangement of the ventilation holes of the frame of the pellicle assembly.

In the example of fig. 4, an aluminum alloy frame a 7075-T651 having a frame outer dimension of 149mm × 122mm × 5.8mm and a frame thickness of 2mm was prepared as a pellicle frame, and a vent hole having a diameter of 0.5mm was provided at the center (four positions in total) of each side face of the frame and at a position 20mm away from each side face corner (twelve positions in total).

In the example of fig. 5, the same pellicle frame is used, and a total of thirty-six 0.5mm vent holes are provided in ten positions on each side surface of each long side and eight positions on each side surface of each short side of the frame.

In the embodiment of fig. 6, different numbers of ventilation holes are provided on the opposite sides of the long side and the short side, wherein the ratio of long side 1/long side 2 is 9/3, and the ratio of short side 1/short side 2 is 7/3.

The experimental conditions for confirming the experiment are typically described in terms of several experimental numbers. Other test numbers are used.

[ experiment No. 6 ]: first, an aluminum alloy frame A7075-T651 having an outer frame dimension of 149mm × 122mm × 5.8mm and a frame thickness of 2mm was prepared as a pellicle frame, and twelve total vent holes having a diameter of 0.5mm were provided at eight positions 20mm from the corner at four positions in the center of one side surface of the frame. Then, a tapered local flattening portion having a width of 10mm, a height of 5mm, a depth of 1mm, and a wall surface angle of 135 ° was provided with the twelve vent holes as the center.

After washing the surface, the surface was washed with fine glass beads and then discharged under a discharge pressure of about 137.1kPa (1.5 kg/cm)²) The sandblasting apparatus of (1) was subjected to surface treatment for 1 minute to roughen the surface. Then, the resultant was treated with NaOH solution for 10 seconds and washed, and then anodized in 14% sulfuric acid aqueous solution at a liquid temperature of 18 ℃ at a formation voltage of 10V (1.3A). Then, black dyeing and hole sealing treatment are performed to form a black oxide film on the surface. Thereafter, the cleaning treatment was performed for 5 minutes using ultrapure water and an ultrasonic cleaning apparatus.

Next, a silicone adhesive of 10 μm was applied to the inner surface of the frame by a spray coating apparatus. Then, a filter made of PTFE, having a dust filtration size of 0.1 to 3.0 μm, a filtration degree of 99.9999%, a width of 8mm, a height of 2.5mm and a thickness of 300 μm is provided on the vent hole. The filter is provided in the structure of a filter for removing dust.

Then, Teflon AF1600 (trade name, manufactured by Du Pont, U.S.A.) was dissolved in a fluorine-based solvent Fluorinert FC-75 (trade name, manufactured by 3M, U.S.A.) to prepare a solution having a concentration of 8%.

Then, a transparent thin film having a thickness of 0.8 μm was formed from the solution on the surface of a mirror-polished silicon substrate having a diameter of 200mm and a thickness of 600 μm by a spin coater.

Then, a frame having an outer dimension of 200mm × 200mm × 5mm and a width and thickness of 5mm was bonded to the film with an epoxy adhesive Araldite Rapid (trade name, manufactured by Showa high-molecular (Strand)) and peeled from the surface of the silicon substrate.

Next, a silicone adhesive was applied to one end surface of the aluminum alloy frame prepared as described above, and the frame was dried and cured by heating at 100 ℃ for 10 minutes. Then, a fluorine-based high molecular weight polymer CTX (trade name, manufactured by Asahi glass (Strand) Ing.) diluted in a fluorine-based solvent CT Solv180 (trade name, manufactured by Asahi glass (Strand) Ing.) was applied to the other end surface of the aluminum alloy frame, and the resultant was heated at 100 ℃ for 10 minutes to dry and harden the polymer.

A PET gasket is prepared and is bonded to a reticle adhesive by a gasket bonding apparatus having an image processing and positioning mechanism using a CCD camera.

Next, a frame was bonded to the surface of the prepared film of teflon AF1600 (trade name, Du Pont, usa), and then the frame and the film were bonded together by heating the frame with an IR lamp. The two frames have the joint face of the pellicle frame facing upward and are fixed by a fixing jig so that there is no deviation in the relative positions.

Then, the frame outside the pellicle frame was lifted and fixed, and about 490Pa (0.5 g/cm) was applied to the film outside the pellicle frame²) The tension of (2).

Next, Fluorinert FC75 (trade name manufactured by Du Pont) was dropped onto a cutter attached to a horizontal articulated robot arm at a rate of 10 μ l per minute using a tube dispenser, and the cutter was moved along the peripheral portion of the adhesive portion of the pellicle frame to cut off and remove an unnecessary portion of the pellicle outside the pellicle frame.

The completed pellicle was cleaned under a condition that the surface residual acid content concentration was 1ppb or less, and was attached to a 6-inch photomask substrate made of quartz glass on which a Cr (chromium) test pattern was formed. Then, it is mounted on an ArF excimer laserOn a scanner NSR S306C (trade name, manufactured by Nikon corporation), and on the reticle surface at an exposure intensity of 0.01 mJ/cm²500J/cm of light irradiation with a repetition frequency of 4000 Hz/pulse²The irradiation amount of (3).

The contamination condition of the irradiated 6-inch photomask was observed by a laser foreign matter inspection apparatus, and it was found that neither the test pattern portion nor the glass portion produced mist or foreign matter.

[ experiment No. 7 ]: first, an aluminum alloy frame A7075-T651 having an outer frame dimension of 149mm × 122mm × 5.8mm and a frame thickness of 2mm was prepared as a pellicle frame, and a total of thirty-six 0.5mm vent holes were provided in ten positions on one long side and eight positions on the short side of the frame. Then, tapered local flat portions having a width of 139mm, a height of 5mm, a width of 110mm, a height of 5mm, and a wall surface angle of 135 ° were provided on the long side and the short side including the thirty-six vent holes.

After washing the surface, the surface was washed with fine glass beads and then discharged under a discharge pressure of about 137.1kPa (1.5 kg/cm)²) The sandblasting apparatus of (1) was subjected to surface treatment for 1 minute to roughen the surface. Then, the resultant was treated with NaOH solution for 10 seconds and washed, and then anodized in 14% sulfuric acid aqueous solution at a liquid temperature of 18 ℃ at a formation voltage of 10V (1.3A). Then, black dyeing and hole sealing treatment are performed to form a black oxide film on the surface. Thereafter, the cleaning treatment was performed for 5 minutes using ultrapure water and an ultrasonic cleaning apparatus.

Next, a silicone adhesive of 10 μm was applied to the inner surface of the frame by a spray coating apparatus. Then, a filter made of PTFE, having a dust filtration size of 0.1 to 3.0 μm, a filtration degree of 99.9999%, a width of 8mm, a height of 2.5mm and a thickness of 300 μm is provided on the vent hole. The filter is provided with a dust removal filter structure having a chemical filter on the outer side.

Then, Teflon AF1600 (trade name, manufactured by Du Pont, U.S.A.) was dissolved in a fluorine solvent Fluorinert FC-75 (trade name, manufactured by 3M, U.S.A.) to prepare a solution having a concentration of 8%.

Then, a transparent thin film having a thickness of 0.8 μm was formed from the solution on a silicon substrate surface having a diameter of 200mm and a thickness of 600 μm and subjected to mirror polishing by a spin coater.

Then, a frame having an outer dimension of 200mm × 200mm × 5mm and a width and thickness of 5mm was bonded to the film with an epoxy adhesive Araldite Rapid (trade name, manufactured by Showa high-molecular (Strand)) and peeled from the surface of the silicon substrate.

Next, a silicone adhesive was applied to one end surface of the aluminum alloy frame prepared as described above, and the frame was dried and cured by heating at 100 ℃ for 10 minutes. Then, a fluorine-based high molecular weight polymer CTX (trade name, manufactured by Asahi glass (Strand) Ing.) diluted in a fluorine-based solvent CT Solv180 (trade name, manufactured by Asahi glass (Strand) Ing.) was applied to the other end surface of the aluminum alloy frame, and the resultant was heated at 100 ℃ for 10 minutes to dry and harden the polymer.

A PET gasket is prepared and is bonded to a reticle adhesive by a gasket bonding apparatus having an image processing and positioning mechanism using a CCD camera.

Next, a frame was bonded to the surface of the prepared film of teflon AF1600 (trade name, Du Pont, usa), and then the frame and the film were bonded together by heating the frame with an IR lamp. The two frames have the joint face of the pellicle frame facing upward and are fixed by a fixing jig so that there is no deviation in the relative positions.

Then, the frame outside the pellicle frame was lifted and fixed, and about 490Pa (0.5 g/cm) was applied to the film outside the pellicle frame²) The tension of (2).

Next, Fluorinert FC75 (trade name manufactured by Du Pont) was dropped onto a cutter attached to a horizontal articulated robot arm at a rate of 10 μ l per minute using a tube dispenser, and the cutter was moved along the peripheral portion of the adhesive portion of the pellicle frame to cut off and remove an unnecessary portion of the pellicle outside the pellicle frame.

The completed pellicle was cleaned under a condition that the surface residual acid content concentration was 1ppb or less, and was attached to a 6-inch photomask substrate made of quartz glass on which a Cr (chromium) test pattern was formed. Then, it was mounted on an ArF excimer laser scanner NSR S306C (trade name, manufactured by Nikon corporation) and exposed on the surface of a reticle at an exposure intensity of 0.01 mJ/cm²500J/cm of light irradiation with a repetition frequency of 4000 Hz/pulse²The irradiation amount of (3).

The contamination condition of the irradiated 6-inch photomask was observed by a laser foreign matter inspection apparatus, and it was found that neither the test pattern portion nor the glass portion produced mist or foreign matter.

[ experiment No. 12 ]: first, an aluminum alloy frame A7075-T651 having an outer frame dimension of 149mm X122 mm X5.8 mm and a frame thickness of 2mm was prepared as a pellicle frame, and a vent hole having a diameter of 0.5mm was provided in the center of one side surface of the frame.

After washing the surface, the surface was washed with fine glass beads and then discharged under a discharge pressure of about 137.1kPa (1.5 kg/cm)²) The sandblasting apparatus of (1) was subjected to surface treatment for 1 minute to roughen the surface. Then, the resultant was treated with NaOH solution for 10 seconds and washed, and then anodized in 14% sulfuric acid aqueous solution at a liquid temperature of 18 ℃ at a formation voltage of 10V (1.3A). Then, black dyeing and hole sealing treatment are performed to form a black oxide film on the surface. Thereafter, the cleaning treatment was performed for 5 minutes using ultrapure water and an ultrasonic cleaning apparatus.

Next, a silicone adhesive of 1 μm was applied to the inner surface of the frame by a spray coating apparatus.

Then, a filter made of PTFE, having a dust filtration size of 0.1 to 3.0 μm, a filtration degree of 99.9999%, a width of 9.5mm, a height of 2.5mm and a thickness of 300 μm is provided on the vent hole. The filter is provided with a dust removal filter structure having a chemical filter on the outer side.

Subsequently, Teflon AF1600 (trade name, manufactured by Du Pont, U.S.A.) was dissolved in a fluorine solvent Fluorinert FC-75 (trade name, manufactured by 3M, U.S.A.) to prepare a solution having a concentration of 8%.

Then, a transparent thin film having a thickness of 0.8 μm was formed from the solution on the surface of a mirror-polished silicon substrate having a diameter of 200mm and a thickness of 600 μm by a spin coater.

Then, a frame having an outer dimension of 200mm × 200mm × 5mm and a width and thickness of 5mm was bonded to the film with an epoxy adhesive Araldite Rapid (trade name, manufactured by Showa high-molecular (Strand)) and peeled from the surface of the silicon substrate.

Next, a silicone adhesive was applied to one end surface of the aluminum alloy frame prepared as described above, and the frame was dried and cured by heating at 100 ℃ for 10 minutes. Then, a fluorine-based high molecular weight polymer CTX (trade name, manufactured by Asahi glass (Strand) Ing.) diluted in a fluorine-based solvent CT Solv180 (trade name, manufactured by Asahi glass (Strand) Ing.) was applied to the other end surface of the aluminum alloy frame, and the resultant was heated at 100 ℃ for 10 minutes to dry and harden the polymer.

A PET gasket is prepared and is bonded to a reticle adhesive by a gasket bonding apparatus having an image processing and positioning mechanism using a CCD camera.

Next, a frame was bonded to the surface of the prepared film of teflon AF1600 (trade name, Du Pont, usa), and then the frame and the film were bonded together by heating the frame with an IR lamp. The two frames have the joint face of the pellicle frame facing upward and are fixed by a fixing jig so that there is no deviation in the relative positions.

Then, the frame outside the pellicle frame was lifted and fixed, and about 490Pa (0.5 g/cm) was applied to the film outside the pellicle frame²) The tension of (2).

Next, Fluorinert FC75 (trade name manufactured by Du Pont) was dropped onto a cutter attached to a horizontal articulated robot arm at a rate of 10 μ l per minute using a tube dispenser, and the cutter was moved along the peripheral portion of the adhesive portion of the pellicle frame to cut off and remove an unnecessary portion of the pellicle outside the pellicle frame.

The completed pellicle was cleaned under a condition that the surface residual acid content concentration was 1ppb or less, and was attached to a 6-inch photomask substrate made of quartz glass on which a Cr (chromium) test pattern was formed. Then, it was mounted on an ArF excimer laser scanner NSR S306C (trade name, manufactured by Nikon corporation) and exposed on the surface of a reticle at an exposure intensity of 0.01 mJ/cm²500J/cm of light irradiation with a repetition frequency of 4000 Hz/pulse²The irradiation amount of (3).

The contamination on the irradiated 6-inch photomask was observed by a laser foreign matter inspection apparatus, and it was found that the haze or foreign matter was not generated in the test pattern portion, but was generated in the glass portion. The sample was analyzed by a laser Raman spectrometer to confirm that it was ammonium sulfate.

[ experiment No. 13 ]: first, an aluminum alloy frame A7075-T651 having an outer frame dimension of 149mm × 122mm × 5.8mm and a frame thickness of 2mm was prepared as a pellicle frame, and twelve total vent holes having a diameter of 0.5mm were provided at eight positions 20mm from the corner at four positions in the center of one side surface of the frame. Then, a partial flattening portion having a width of 10mm, a height of 5mm, a depth of 1mm and a wall surface angle of 90 ° was provided with the twelve vent holes as the center.

After washing the surface, the surface was washed with fine glass beads and then discharged under a discharge pressure of about 137.1kPa (1.5 kg/cm)²) The sandblasting apparatus of (1) was subjected to surface treatment for 1 minute to roughen the surface. Then, the resultant was treated with NaOH solution for 10 seconds and washed, and then anodized in 14% sulfuric acid aqueous solution at a liquid temperature of 18 ℃ at a formation voltage of 10V (1.3A). Then, black dyeing and hole sealing treatment are performed to form a black oxide film on the surface. Thereafter, the cleaning treatment was performed for 5 minutes using ultrapure water and an ultrasonic cleaning apparatus.

Next, a silicone adhesive of 10 μm was applied to the inner surface of the frame by a spray coating apparatus.

Then, a filter made of PTFE, having a dust filtration size of 0.1 to 3.0 μm, a filtration degree of 99.9999%, a width of 8mm, a height of 2.5mm and a thickness of 300 μm is provided on the vent hole. The filter is provided with a dust removal filter structure having a chemical filter on the outer side.

Subsequently, Teflon AF1600 (trade name, manufactured by Du Pont, U.S.A.) was dissolved in a fluorine solvent Fluorinert FC-75 (trade name, manufactured by 3M, U.S.A.) to prepare a solution having a concentration of 8%.

Then, a transparent thin film having a thickness of 0.8 μm was formed from the solution on the surface of a mirror-polished silicon substrate having a diameter of 200mm and a thickness of 600 μm by a spin coater.

Then, a frame having an outer dimension of 200mm × 200mm × 5mm and a width and thickness of 5mm was bonded to the film with an epoxy adhesive Araldite Rapid (trade name, manufactured by Showa high-molecular (Strand)) and peeled from the surface of the silicon substrate.

Next, a silicone adhesive was applied to one end surface of the aluminum alloy frame prepared as described above, and the frame was dried and cured by heating at 100 ℃ for 10 minutes. Then, a fluorine-based high molecular weight polymer CTX (trade name, manufactured by Asahi glass (Strand) Ing.) diluted in a fluorine-based solvent CT Solv180 (trade name, manufactured by Asahi glass (Strand) Ing.) was applied to the other end surface of the aluminum alloy frame, and the resultant was heated at 100 ℃ for 10 minutes to dry and harden the polymer.

A PET gasket is prepared and is bonded to a reticle adhesive by a gasket bonding apparatus having an image processing and positioning mechanism using a CCD camera.

Next, a frame was bonded to the surface of the prepared film of teflon AF1600 (trade name, Du Pont, usa), and then the frame and the film were bonded together by heating the frame with an IR lamp. The two frames have the joint face of the pellicle frame facing upward and are fixed by a fixing jig so that there is no deviation in the relative positions.

Then, the frame outside the pellicle frame was lifted and fixed, and about 490Pa (0.5 g/cm) was applied to the film outside the pellicle frame²) The tension of (2).

Next, Fluorinert FC75 (trade name manufactured by Du Pont) was dropped onto a cutter attached to a horizontal articulated robot arm at a rate of 10 μ l per minute using a tube dispenser, and the cutter was moved along the peripheral portion of the adhesive portion of the pellicle frame to cut off and remove an unnecessary portion of the pellicle outside the pellicle frame.

The completed pellicle was cleaned under a condition that the surface residual acid content concentration was 1ppb or less, and was attached to a 6-inch photomask substrate made of quartz glass on which a Cr (chromium) test pattern was formed. Then, it was mounted on an ArF excimer laser scanner NSR S306C (trade name, manufactured by Nikon corporation) and exposed on the surface of a reticle at an exposure intensity of 0.01 mJ/cm²500J/cm of light irradiation with a repetition frequency of 4000 Hz/pulse²The irradiation amount of (3).

The contamination on the irradiated 6-inch photomask was observed by a laser foreign matter inspection apparatus, and it was found that the haze or foreign matter was not generated in the test pattern portion, but was generated in the glass portion. The sample was analyzed by a laser Raman spectrometer to confirm that it was ammonium sulfate. The results of the experiments carried out in the same manner are collated in Table 1.

[ Table 1]

Table 1: air vent distribution, local flattening portion taper angle effect

Note: "0 degree" of "local flattening draft angle" means that there is no local flattening

According to table 1, the experiment numbers 1, 2, 10, 11 and 13 were inappropriate for the "local leveling angle" and the number of the "local leveling" portion of the experiment number 12 was insufficient, so that the "generation of mist" could not be avoided.

In addition, we can attach various basic materials that the present invention can use.

The filter for dust removal used in the present invention is not particularly limited in shape, number, and installation position as long as it can be installed at the position of the vent hole. Examples of the filter material include resin (PTFE, nylon 66, etc.), metal (316L stainless steel, etc.), ceramics (aluminum, aluminum nitride, etc.), and the like. In addition, it is also preferable to install a chemical filter capable of adsorbing or decomposing chemicals in the environment at a position outside the dust removing filter.

The bonding agent for bonding the protective film may be a conventional one. For example, fluorine-based polymers such as acrylic resin adhesives, epoxy resin adhesives, silicone resin adhesives, fluorine-containing silicone adhesives, and the like are preferable.

Examples of the fluorine-containing polymer include CT69 (trade name, manufactured by Asahi glass Co., Ltd.).

The bonding agent for attaching the reticle may be, for example, a double-sided adhesive tape, a silicone adhesive, an acrylic adhesive, or the like.

In a general production method of the pellicle of the present invention, a pellicle is laid on the upper end face of a pellicle frame with a pellicle bonding adhesive layer interposed therebetween, a reticle bonding adhesive layer is usually provided on the lower end face, and a release layer is peelably bonded to the lower end face of the reticle bonding adhesive layer.

The adhesive layer for sticking the pellicle film provided on the upper end face of the pellicle frame is diluted with a solvent if necessary, then applied to the upper end face of the pellicle frame, and dried and hardened by heating. In this case, the method of applying the bonding agent may be, for example, brush application, spray application, an automatic dispenser, or the like.

The material of the pad for protecting the reticle adhesive used in the present invention is not particularly limited. For example, materials such as PET, PTFE, PFA, PE, PC, PVC, PP, etc. can be used.

Claims (6)

1. A pellicle for lithography, in which a plurality of vent holes are provided in a pellicle frame for lithography and the vent holes are covered with a dust-proof filter, characterized in that,

the pellicle frame for lithography has a thickness of 2mm, a plurality of vent holes are provided at least on one side, a spot-facing portion having a bottom with a depth of 1mm is provided across the plurality of vent holes on at least one side, and a wall surface of the spot-facing portion is tapered.

2. A pellicle for lithography as claimed in claim 1,

at least one vent hole and one countersink are provided on each of the sides other than the at least one side.

3. The pellicle for lithography according to claim 1 or 2, characterized in that,

the angle between the inclined plane on the inclined plane of the tapered processing and the outer side surface of the frame is larger than 90 degrees and smaller than 180 degrees.

4. The pellicle for lithography according to claim 1 or 2, characterized in that,

the spot facing portion is circular.

5. The pellicle for lithography according to claim 1 or 2, characterized in that,

the spot facing portion is formed in an elliptical shape.

6. The pellicle for lithography according to claim 1 or 2, characterized in that,

the spot facing portion is rectangular.