HK1174397A1

HK1174397A1 - Dust-prevention film, the manufacturing method thereof and the dust-prevention component with the film attached

Info

Publication number: HK1174397A1
Application number: HK13101203.6A
Authority: HK
Inventors: 関原一敏
Original assignee: 信越化学工业株式会社
Priority date: 2011-03-31
Filing date: 2013-01-28
Publication date: 2013-06-07
Also published as: JP5279862B2; KR20120111997A; JP2012212043A; CN102736400A; TW201305721A; CN102736400B; TWI446104B

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive pellicle film suited to a lithography process of applying ultraviolet light including i line, h line and g line and having a wavelength region of 350-450 nm, and having light resistance.SOLUTION: The pellicle film for pellicles is used in a lithography process for applying ultraviolet light with the wavelength range of 350-450 nm. The pellicle film includes, on the surface of a raw material pellicle film 21 at least in an exposure light source side, an ultraviolet light absorbing layer 22 that has an average transmittance of 90% or more to the ultraviolet light with the wavelength region of 350-450 mm, and an average transmittance of 50% or less to the ultraviolet light with the wavelength region of 200-300 nm.

Description

Dustproof film, its manufacturing method and dustproof film assembly adhered by said film

Technical Field

The present invention relates to a pellicle used as a dust-proof material in the production of a semiconductor device, an IC package, a printed circuit board, a liquid crystal display, an organic EL display, or the like, and more particularly to a pellicle used in an ultraviolet lithography process using, as an exposure light source, any one of i-line (365 nm), h-line (405 nm), and g-line (436 nm) or a combination thereof, a method for producing the same, and a pellicle to which the pellicle is tightly attached.

Background

In the manufacture of semiconductors such as LSI and super LSI, circuit boards such as IC packages and printed boards, liquid crystal displays and organic EL displays, a photoresist is provided on the surface of a semiconductor wafer, a package substrate or a display original plate, and then light is irradiated thereto through a photomask having a pattern and developed to produce a pattern. In this case, if dust adheres to a photomask or a reticle (hereinafter, referred to as a photomask), the dust absorbs or bends light, and thus the transferred pattern is deformed, the edge of the pattern is blurred, the substrate is changed to black, and the size, quality, appearance, and the like of the final product are deteriorated.

Therefore, these operations are usually performed in a clean room, but even so it is difficult to make the photomask clean from time to time. Therefore, the pellicle is attached as a dust-proof object to the surface of the photomask and then exposed. In this case, the foreign matter is attached to the pellicle film assembly without being directly attached to the surface of the photomask, and thus the foreign matter on the pellicle film assembly is not involved in the transfer printing by aligning the focus with the pattern of the photomask during photolithography.

In general, a pellicle is manufactured by attaching or bonding a transparent pellicle film, which transmits light well, to an upper end surface of a pellicle frame made of aluminum, stainless steel, engineering plastic, or the like. Further, an adhesive layer made of polybutene resin, polyvinyl acetate resin, acrylic resin, thermosol adhesive, silicone resin, or the like, and a release layer (release sheet) for protecting the adhesive layer are provided at the lower end of the pellicle frame for mounting the photomask.

In addition, in a state where the pellicle is attached to the photomask, in order to prevent a difference in air pressure between the space enclosed inside the pellicle and the outside, a small hole for air pressure adjustment is provided in a part of the pellicle frame, and a filter may be provided in order to prevent foreign matter from being introduced into the moving air passing through the small hole.

As the dustproof film, an optimum material corresponding to a light source used for exposure is selected. For example, ArF laser (193 nm) or KrF laser (248 nm) is used in high-altitude, and fluorine-based resins having sufficient transmittance and light resistance to light of that wavelength are used (patent document 1).

In high-altitude applications in which exposure is carried out using i-line (365 nm), h-line (405 nm) and g-line (436 nm), cellulose resins such as nitrocellulose, ethylcellulose and cellulose propionate, polyvinyl acetal resins and cycloolefin resins can be used (patent documents 2, 3 and 4). As the light source, a high-pressure mercury lamp or an ultrahigh-pressure mercury lamp is generally used.

A high pressure mercury lamp and an extra high pressure mercury lamp have a wide wavelength characteristic having several peaks between 254 and 577 nm. Among them, light having the highest intensity of i-line (365 nm), then g-line (436 nm) and h-line (405 nm) can be used favorably, and 313 nm is occasionally used, from the viewpoint of the amount of luminescence and light energy in lithography. In recent years, high importance has been placed on displays, and for example, light of 365 nm to 436 nm is used instead of light of a specific wave.

The fluororesin described above has little absorption at short wavelengths, and can be used at wavelengths of short-wavelength and high-energy KrF laser light and ArF laser light, and therefore, of course, there is no problem at all even when i-ray, g-ray, and the like, which are lower in energy than those of the KrF laser light and the ArF laser light, are used. However, the fluororesin has a disadvantage of extremely high cost. Therefore, in general, in the wavelength region from i-line to g-line, cellulose-based resins and the like which are easy to use are often used in consideration of various characteristics as a dustproof film material.

In addition, a multilayer structure in which an antireflection film is provided on one surface or both surfaces thereof for the purpose of improving the light transmittance of the dustproof thin film is also used. In particular, this is particularly the case when a cellulose resin having a high refractive index and a high reflectance is used as an antireflection film of a fluorine resin. Further, there is also a case where a silicone adhesive layer is provided on the inner surface of the dustproof thin film, thereby fixing foreign matter adhering to the inner side of the dustproof thin film and preventing the foreign matter from falling onto the photomask (patent document 5). The organosiloxane resin has excellent light transmittance and high transmittance to light having a short wavelength, and thus can be used for lamination on a dust-proof film.

[ Prior art documents ]

[ patent document ]

[ patent document 1 ] Japanese patent application laid-open No. 03-39963

[ patent document 2 ] Japanese patent application laid-open No. Hei 01-100549

[ patent document 3 ] Japanese patent application laid-open No. Hei 01-172430

[ patent document 4 ] Japanese patent application laid-open No. 2010-152308

Japanese patent application laid-open No. 5-88359

In recent years, in the lithography process, higher exposure intensity is required for drawing a circuit with a thinner line and for improving productivity. The exposure intensity is increased, and aging of the dustproof thin film by ultraviolet rays is promoted, so that problems such as reduction in film thickness, reduction in transmittance, and occurrence of hais (ヘイズ) occur. Specifically, although the portion shielded from light by the chromium (Cr) layer of the photomask is not irradiated with ultraviolet rays and thus does not change, the surface of the pellicle film is directly irradiated with ultraviolet rays without the Cr layer (the portion where the pattern is drawn), and the film of the portion is damaged.

As described above, the exposure light source is used in a high-pressure mercury lamp or a very-high-pressure mercury lamp, and light having not only i-line, h-line, and g-line for exposure but also other wavelengths, and typical examples thereof include short-wavelength light such as 254 nm, 302 nm, and 313 nm. These short wavelength lights, particularly 254 nm lights, have higher energy than the bond energy of molecules constituting the dust-proofing film such as cellulose resin, and the bond is cut. The molecules with the cleaved bonds are decomposed and gasified, the surface of the pellicle film is scraped, and the film thickness is reduced.

The film thickness of part of the dustproof thin film assembly is reduced, the optical path length is uneven, the surface is uneven except that the optical path length is not satisfactory, light can be scattered, and the transmittance is low. In addition, the membrane intensity is reduced, and even severe high-altitude buildings cause uneven tension on the dustproof thin film, and wrinkles are generated on the surface of the dustproof thin film.

To prevent such a problem, light having a short wavelength, which is not used for patterning such as 254 nm, 302 nm, and 313 nm, among light generated from an exposure light source, may be removed. Examples of the method include a method in which a filter for removing only the short-wavelength light is inserted into an optical path from an exposure light source to a photomask, and a method in which a mirror for reflecting light other than the short-wavelength light is inserted. Further, a layer having the same filter function may be added to the side of the pattern surface where no photomask is provided. These filter functions are formed by, for example, forming TiO on the opposite side of the pattern surface of the filter substrate such as quartz glass or the photomask itself₂，ＺｎＯ₂，ＣｅＯ₂And inorganic materials having absorption in a short wavelength region, etc., can be obtained by attaching them by a method such as vapor deposition or sputtering. However, the cost of such processing is not necessarily low, and these materials have a high refractive index and a large reflection, and are used for exposure in some casesThe intensity of the light becomes low. Therefore, the correspondence is not made on the exposure machine and photomask sides, but on the pellicle assembly side.

However, it is extremely difficult to provide the above-mentioned inorganic material to the dust-proof film. In the case of vapor deposition and sputtering, it is necessary to house the dustproof thin film in a vacuum chamber, and this is because a large amount of air is taken in and out of the vacuum chamber when the pressure is reduced and the pressure is returned to the atmospheric pressure, and a large amount of foreign matter adheres to the dustproof thin film. However, the dust-proof film cannot be cleaned unlike a glass substrate or the like. Therefore, the high-cleanliness dustproof thin film has a disadvantage in that it is exposed to foreign matters.

For the above reasons, there has been no dust-proofing film that is excellent in durability against short-wavelength light and is made of an inexpensive cellulose-based resin. Therefore, this method of attaching and replacing the dust-proof film has to be adopted before the problem occurs.

Disclosure of Invention

Accordingly, the 1 st object of the present invention is to provide an inexpensive dustproof film which is suitable for exposure using i-line, h-line and g-line and has high resistance to ultraviolet rays having a short wavelength of 254 nm, 313 nm and the like.

The 2 nd object of the present invention is to provide a method for producing a dustproof thin film which is used in an ultraviolet lithography process in a wavelength range of 350 to 450 nm, is inexpensive, and has excellent durability.

It is a further object of the present invention to provide an inexpensive pellicle for use in ultraviolet lithography in the wavelength range of 350 to 450 nm.

The above-described objects of the present invention are to provide a pellicle for pellicle use in ultraviolet irradiation lithography process using a wavelength region of 350 to 450 nm, the pellicle being characterized in that a raw pellicle film has an ultraviolet absorbing layer on at least the surface on the exposure light source side, the ultraviolet absorbing layer having an average transmittance of 90% or more with respect to ultraviolet rays in the wavelength region of 350 to 450 nm and an average transmittance of 50% or less with respect to ultraviolet rays in the wavelength region of 200 to 300 nm. The invention also provides a manufacturing method of the dustproof film and a dustproof film assembly using the dustproof film.

In the present invention, it is preferable that an antireflection layer is further provided on the ultraviolet absorbing layer. The ultraviolet absorbing layer is preferably made of a silicone resin, and the refractive index of the ultraviolet absorbing layer is preferably 1.50 or less.

Effective fruit of the invention

The dustproof film of the present invention is an excellent dustproof film which has high light resistance to components of 300 nm or less which are present as unnecessary components in exposure light, and has greatly improved light resistance compared with the conventional dustproof film, although the same inexpensive material as the conventional dustproof film is used, for example, cellulose-based resin, polyvinyl acetal resin, cycloolefin-based resin, etc. Therefore, higher exposure intensity can be used, and improvement in exposure quality and quantity can be achieved. In addition, the film thickness can be reduced during use, and the problems such as the occurrence of wrinkles and blur can be prevented, so that the exposure quality can be maintained for a long period of time.

Drawings

FIG. 1 is a sectional view showing the basic configuration of a pellicle of the present invention;

FIG. 2 is a cross-sectional view of a dust control film of the present invention having an ultraviolet absorbing layer;

FIG. 3 is a cross-sectional view of a dustproof thin film of the present invention further adding an anti-reflection layer on the ultraviolet absorbing layer;

FIG. 4 is a schematic perspective view of the pellicle of the present invention.

[ description of the symbols ]

11 dustproof pellicle assembly frame

12 adhesive layer

13 adhesive layer

14 Release sheet

15 dust-proofing film of the present invention having ultraviolet absorbing layer

21 raw material dustproof film

22 ultraviolet absorbing layer

23 anti-reflection layer

40 pellicle of the invention

41 pellicle assembly frame

42 groove

43 clamp hole

44 adhesive layer

45 adhesive layer

46 air vent

47 filter

48 dust-proofing film of the present invention having ultraviolet absorbing layer

Detailed Description

The material of the dustproof film as the raw material of the dustproof film of the present invention may be suitably selected from known materials, and examples thereof include cellulose resins such as nitrocellulose, ethyl cellulose, cellulose acetate, cellulose propionate, and cellulose levulinate, polyvinyl acetal resins, and cycloolefin resins, and inexpensive materials similar to those used in the prior art can be used. These materials have sufficient resistance to light having a wavelength of 350 to 450 nm used for patterning, but have low resistance to short wavelengths of 300 nm or less which are present as unnecessary components in exposure light, and thus are rapidly aged. In the present invention, the ultraviolet absorbing layer provided on the incident surface side of the dustproof thin film can prevent the short-wavelength component from reaching the raw material dustproof thin film, thereby greatly improving the light resistance.

The ultraviolet absorbing layer particularly has an average transmittance of 90% or more for ultraviolet rays in a wavelength region of 350 to 450 nm, and an average transmittance of 50% or less for ultraviolet rays in a wavelength region of 200 to 300 nm. The material of such an ultraviolet absorbing layer can be selected as appropriate from known materials, and in the present invention, a silicone resin is particularly preferably used for the ultraviolet absorbing layer. When a silicone resin is used as the ultraviolet absorbing layer, unlike the inorganic material, the silicone resin can be applied in a solution state dissolved in a solvent to form a film, and the production of the dustproof film of the present invention is possible in the same manner as in the production of usual dustproof films. Thus, a clean dust-proof film with less foreign matters can be obtained. Further, the silicone resin is excellent in light resistance and has an advantage that deterioration due to ultraviolet absorption is extremely small.

In the dustproof film of the present invention, it is preferable that an antireflection layer is further provided in addition to the ultraviolet absorbing layer. The antireflection layer may be formed by taking into consideration the material, the film thickness, and the position of the ultraviolet absorbing layer according to the refractive index of the ultraviolet absorbing layer. The antireflection layer may be provided as the outermost layer of the dustproof film on the incident side, the outermost layer on the emission side or the outermost layers on both sides thereof, or may be provided between the ultraviolet absorbing layer and the raw dustproof film depending on the combination of refractive indexes. The material of the antireflection layer is not limited to 1 type, and a plurality of types may be combined, and the antireflection layer may have a multilayer structure.

In the present invention, the refractive index of the ultraviolet absorbing layer is 1.50 or less, and the ultraviolet absorbing layer may have a function as an anti-reflection layer in addition to the ultraviolet absorbing function.

The dustproof thin film of the present invention is preferably formed by coating a material solution of one of the outermost layers among the raw dustproof thin film, the ultraviolet absorbing layer and the antireflection layer constituting the dustproof thin film of the present invention on a film formation substrate, drying and curing the material solution, repeating the same coating, drying and curing steps for the constituent materials of each layer in the order of a desired film structure on the dried and cured layer, and finally peeling the entire dustproof thin film laminated on the film formation substrate from the film formation substrate. This method can provide the dust-proof film of the present invention having an ultraviolet absorbing layer with little adhesion of foreign matters, as in the case of the conventional method for producing a dust-proof film.

The exposure light source side of the dustproof thin film is a main cause of deterioration of the raw dustproof thin film, and the dustproof thin film of the invention has an ultraviolet absorption layer for absorbing ultraviolet rays in a wavelength region of 200 to 300 nm, so that the raw dustproof thin film can be a dustproof thin film with excellent light resistance without using expensive fluorine-based resin. In particular, a high-gloss resin can be used as the ultraviolet absorbing layer as described above, and the ultraviolet absorbing layer can be applied by dissolving in a solvent, and the dustproof thin film of the present invention can be produced in the same manner as in high-gloss resin produced by a usual dustproof thin film, and a dustproof thin film which is excellent in durability, little in foreign matters, and inexpensive and clean can be obtained.

FIG. 1 is a cross-sectional view showing the outer shape of a pellicle of the present invention. In the figure, reference numeral 15 denotes a dust-proof film of the present invention, which is attached to the dust-proof film module frame 11 with an appropriate tension via the adhesive layer 13. Reference numeral 12 denotes an adhesive layer to which the pellicle is attached to the photomask in use, and 14 denotes a release sheet for protecting the adhesive layer before use.

Fig. 2 is an enlarged cross-sectional view of the portion a of the dustproof film in fig. 1. The symbol 21 is a raw material dust-proof film, and the symbol 22 is an ultraviolet absorbing layer. Fig. 3 is an enlarged cross-sectional view of the portion a of the dustproof film in fig. 1, similar to fig. 2, and shows an embodiment in which an antireflection layer 23 is added to the ultraviolet absorbing layer 22.

The pellicle of the present invention can be used as a pellicle in all kinds of lithography using ultraviolet rays in a wavelength region of 350 to 450 nm, and the wavelength, the use, the size, and the like of the pellicle are not limited. The material of the pellicle frame 11 to which the pellicle of the present invention is attached may be engineering plastic, steel, stainless steel, aluminum alloy, titanium and its alloy, CFRP, or the like, and may be selected from known materials used for pellicle frames.

The material of the raw dustproof thin film 21 used for the dustproof thin film 15 of the present invention may be appropriately selected from known dustproof thin film materials. An expensive material such as a fluorine-based resin excellent in light resistance to light having a wavelength of 350nm or less may be used, but in the present invention, inexpensive materials such as cellulose resins such as nitrocellulose, ethylcellulose, cellulose acetate, cellulose propionate and cellulose acetate propionate, polyvinyl acetal resins and cycloolefin resins are used.

The material of the ultraviolet absorbing layer 22 used in the present invention is preferably an organic substance having an average transmittance of 90% or more to ultraviolet rays in a wavelength region of 350 to 450 nm and an average transmittance of 50% or less to ultraviolet rays in a wavelength region of 200 to 300 nm in a state where the dustproof thin film is coated, and particularly, a material which does not deteriorate and does not generate dust under irradiation of ultraviolet rays is essential. From this viewpoint, in the present invention, as described above, it is preferable to use a silicone resin which not only has high transparency and excellent transmittance, but also has excellent light resistance under irradiation with ultraviolet light having a short wavelength. In addition, the silicone resin before curing can be dissolved in an organic solvent such as toluene or xylene, and thus can be easily applied to form a film.

In the above patent document 5, a silicone resin having a high light transmittance even in a short wavelength range is selected for the purpose of imparting tackiness, but in the present invention, a silicone resin having a drastically decreased light transmittance at a wavelength of 350nm or less which is not used for exposure is selected. Further, although the reliability of adhesion can be improved by fixing foreign matters to the pellicle film, since there is a problem that peeling from the film formation substrate is difficult and it is extremely difficult to manufacture, the present invention does not provide adhesion to the pellicle film. The silicone resin used in the present invention is preferably a linear silicone resin into which a methyl group or a phenyl group is introduced, or an organically modified silicone resin into which a polyether, an epoxy group, an amine group, a carboxyl group, an aralkyl group, a fluoroalkyl group, or the like is introduced. In the present invention, the optical characteristics and the mechanical characteristics are considered from both sides, and a substance having desired characteristics may be selected. The resin is preferably solid in form, and has desired film strength and flexibility. In the present invention, the cured products of the silicone resin and the rubber are not limited to those, and any of a heat curing type, a 2-liquid curing type and an additive reaction type may be used.

In the present invention, the dustproof thin film 15 of the present invention is disposed so that the exposure light passes through the ultraviolet absorbing layer 22 before reaching the raw dustproof thin film 21, that is, the ultraviolet absorbing layer is provided on the light incident side. However, in a case of a high-level office where the ultraviolet absorption layer also serves as the antireflection film 23, the ultraviolet absorption layer 22 may be provided to overlap with the exit side (not shown).

In the present invention, as shown in fig. 3, an antireflection layer 23 may be further added to the ultraviolet absorbing layer 22. In the embodiment of fig. 3, the antireflection layer 23 is provided on the surface of the raw material dustproof film 21 opposite to the surface on which the ultraviolet absorbing layer 22 is provided, but the antireflection layer may be further provided on the ultraviolet absorbing layer 22 in another form. Further, an antireflection layer may be provided between the ultraviolet absorbing layer 22 and the raw material dust-proofing film 21 depending on the refractive index of the ultraviolet absorbing layer 22. The dust-proof film 15 of the present invention includes all of these modes.

The material of the antireflection layer may be appropriately selected from known materials having a refractive index lower than that of the layer adjacent to . For example, a high-grade resin is preferably used in the surface of a dustproof thin film made of a general cellulose resin, and a fluorine resin having a refractive index of about 1.5 and a refractive index of about 1.3 to 1.35 is suitable for the cellulose resin. The film thickness, the number of layers, and the like may be appropriately designed according to known techniques depending on the material used.

For the above reasons, if the refractive index of the ultraviolet absorbing layer 22 is 1.5 or less, the ultraviolet absorbing layer 22 may also function as an anti-reflection layer, and thus the anti-reflection layer may be omitted, or as in the embodiment shown in fig. 3, the anti-reflection layer may be added, and the ultraviolet absorbing layer (also anti-reflection layer) → raw material dust-proofing film → 3 layers of the anti-reflection layer may be formed from the light incident side. This structure has a large number of film-forming cycles and is disadvantageous in terms of cost, but can produce a high-quality effect. In particular, silicone resins developed for optical applications have a refractive index of 1.40 to 1.50, and are suitably used.

In addition, the thickness of the ultraviolet absorbing layer 22 should be determined with importance placed on the ultraviolet transmitting property rather than the design based on the thickness of the antireflection layer. From the viewpoint of the wavelength-light transmittance characteristics of the raw material, it is necessary to determine the film thickness of the ultraviolet absorbing layer 22 in consideration of the fact that the average light transmittance in the wavelength region of 350nm to 450 nm is 90% or more, preferably as high as possible, and the average light transmittance in the wavelength region of 200 to 300 nm is 50% or less.

The method for producing the dustproof film of the present invention will be described in detail below.

The dustproof thin film of the present invention can be basically formed by coating a material solution of an ultraviolet absorbing layer on the surface of a raw material dustproof thin film formed on a smooth substrate. Fig. 3 illustrates a case of a high-level structure of 3 layers of uv absorbing layer, raw material dust-proofing film, and antireflection film, where first, a solution of uv absorbing material is applied to a substrate, such as soda glass, quartz glass, or silicone wafer, which has been polished smoothly, by a known method, such as spin coating, slit and spin coating, or slit coating. The film thickness is determined by design from the transmittance. Then, a solution of the material of the raw material dustproof thin film is optically applied to the ultraviolet absorbing layer 22 formed as described above, and is dried and cured to obtain the raw material dustproof thin film 21. Similarly, a solution of an antireflection material is applied to the raw material dustproof film, dried and cured, and an antireflection layer 23 is further provided on the raw material dustproof film formed as described above.

The various types of deposition described above may be performed according to the structural design of the dustproof thin film of the present invention, and are not limited at all. Here, a description will be given of a film formation method of the ultraviolet absorbing layer of the base, in which the antireflection layer is the lowermost layer, a raw material dust-proof film is formed thereon, and further, the ultraviolet absorbing layer is formed on the raw material dust-proof film. This procedure may be reversed according to the need of the process, and a layer having high releasability from the film formation substrate is preferably used as the lowermost layer (i.e., the film formation substrate side). Further, if necessary, surface treatment for improving peelability may be performed on the surface of the film formation substrate.

As described above, after the cured dustproof thin film 15 of the present invention is obtained on the film-formed substrate, the film is bonded to a frame-shaped peeling jig (not shown) having the same outer shape as the substrate, and the bonded film is gradually pulled up and peeled off, whereby the dustproof thin film of the present invention having the ultraviolet absorbing layer can be obtained.

The dustproof thin film of the present invention thus obtained is bonded to the dustproof thin film module frame to which the adhesive layer is applied. The dustproof thin film component of the invention can be obtained.

The present invention will be further described with reference to the following examples, but the present invention is not limited thereto.

[ example 1 ]

The pellicle frame 41 made of a 5052 aluminum alloy having the shape shown in fig. 4 is manufactured by machining. The pellicle frame 41 is shaped so that the outside dimensions of each corner are 1146 x 1392mm, the inside dimensions are 1124 x 1370 mm rectangular and the thickness is 5.8 mm, and the inside of each corner is R2 and the outside is R6. Further, for treatment, concave holes 43 having a diameter of 2.5 mm and a depth of 2mm were provided at 4 positions on the long side, and grooves 42 having a height of 2mm and a depth of 3 mm were provided at 2 positions on each of the short side and the long side. Further, at both long sides, vent holes 46 having a diameter of 1.5 mm are provided at 8.

The dustproof pellicle assembly frame was carried into a dust free chamber of class 10, cleaned well with a surfactant and pure water, and dried. Then, a silicone adhesive layer was provided as a dust-proof film adhesive layer 45 on one end face of the frame of the dust-proof film module, and a photomask adhesive layer 44 on the other end face thereof, and a silicone adhesive (trade name: KR 3700, manufactured by shin-Etsu chemical industries co., Ltd.) was diluted with toluene, applied by a dispenser pressurized with air, and heat-cured. Then, the filter 47 is attached so as to cover the air vent hole 46 on the side surface of the pellicle frame 41. Finally, a release agent was applied to the surface, and a PET film having a thickness of 150 μm was cut with a cutting tool into a shape almost the same as that of the pellicle frame, and a release sheet (not shown) for protecting the photomask adhesive layer was attached to complete the frame portion.

On a film-forming substrate made of smooth-polished quartz of 1200X 1500 mm X17 mm in thickness, a raw material dustproof thin film material solution in which cellulose propionate (manufactured by Sigma-Aldrich) was diluted with butyl acetate was applied by a slit coating method. In this case, the coating amount was set to 4.0 μm in thickness after drying. The mixture was allowed to stand for 1 hour to dry the solvent to some extent, and then heated at 130 ℃ with an IR lamp (not shown) to form a dustproof film of the raw material.

Then, on the raw material dustproof film, as an ultraviolet absorption layer, a cured silicone rubber (trade name KER-2500, manufactured by shin-Etsu chemical Co., Ltd.) A, B liquid was well mixed, viscosity was adjusted with toluene, and then the mixture was coated by a slit coating method. In this case, the film thickness was adjusted to 1 μm after drying. Thereafter, the reaction mixture was allowed to stand horizontally for 2 hours to smooth the surface, and toluene for dilution was evaporated, and further, the reaction mixture was heated at 100 ℃ for 1 hour and then at 150 ℃ for 5 hours by an IR lamp to complete the reaction and hardening. The refractive index of the ultraviolet absorbing layer was 1.41. The whole was cooled to room temperature, and the ultraviolet absorbing layer was adhered to a frame-shaped stainless steel peeling jig having the same shape as the outer shape of the substrate, and gradually pulled up while removing the electric power, to obtain the dustproof thin film of the present invention as a peeling film.

Then, the ultraviolet absorbing layer is disposed so as to face the side of the dustproof thin film adhesive layer, the dustproof thin film 48 of the present invention having the ultraviolet absorbing layer is adhered to the adhesive layer 45 of the dustproof thin film unit frame 41, and unnecessary films around the dustproof thin film unit frame 41 are cut and removed by a cutter, thereby completing the dustproof thin film unit 40 of the present invention.

In the dustproof thin film module of the present invention thus obtained, the light transmittance of the dustproof thin film was measured with a transmittance measuring instrument (manufactured by tsukamur electronic corporation), and the transmittance was 95.2% on average in the entire wavelength region of wavelength 350 and 450 nm. On the other hand, in the wavelength region of 200 to 300 nm, the average value of transmittance is about 48%.

Further, the obtained pellicle of the present invention was irradiated with a high-pressure mercury lamp, and light resistance was confirmed. In the high-pressure mercury lamp (manufactured by NIU TAIL MOTOR Co., Ltd.), the light passes through the ultraviolet absorbing layer → the dustproof film in this order, and the surface light intensity of the dustproof film is 5000 mW/cm²The transmittance, the change in film thickness and the appearance in the above wavelength region were confirmed. As a result, even when the experiment was carried out until the cumulative energy was 60 kj, no change was observed in the light transmittance, film thickness, and appearance of the irradiated portion.

[ example 2 ]

Similarly to example 1, a dustproof pellicle membrane module frame made of a 5052 aluminum alloy having an outer dimension of 280 × 280, an inner dimension of 270 × 270, and a height of 4.8 mm was fabricated, and cleaned well with a surfactant and pure water in a class 10 clean room, and completely dried. Then, a silicone adhesive (trade name: X-40-3004A, manufactured by shin-Etsu chemical Co., Ltd.) layer as an adhesive layer to which a photomask was attached was provided on one end face, and a silicone adhesive (trade name: KR 3700, manufactured by shin-Etsu chemical Co., Ltd.) was applied as an adhesive for bonding the dustproof film of the present invention on the other end face, and the resultant was cured by heating in an oven. Then, a release sheet obtained by coating a PET film having a thickness of 150 μm with a fluorine-modified silicone was cut into a frame shape having almost the same shape as the outer dimensions of the frame, and was attached to the adhesive layer.

Next, on a quartz substrate having a thickness of 8 mm of 350X 350 x in which the surface was polished smoothly and cleaned well, a fluororesin (trade name: EF-L174, manufactured by Mitsubishi Material Co., Ltd.) diluted with a fluorine-based solvent (trade name: CYTOP, manufactured by Asahi glass Co., Ltd.) was coated by a spin coating method. The film thickness was adjusted so that the film thickness after drying was 0.07. mu.m. After coating, the film-forming substrate was dried while being kept horizontal until the solvent hardly flowed, and then heated to 180 ℃ with a hot plate to completely remove the solvent.

Next, cellulose propionate (manufactured by Sigma-Aldrich) was diluted with butyl acetate, and the resulting solution was applied onto the surface of the fluororesin layer by spin coating. The film thickness was adjusted so that the dried cellulose resin layer became 4 μm. Then, the film formation substrate was dried while being kept horizontal until the solvent hardly flowed, and then heated to 130 ℃ on a hot plate to completely remove the solvent.

Next, as an ultraviolet absorbing layer, solution A and solution B of an organically modified silicone resin (trade name: SCR 1011, manufactured by shin-Etsu chemical Co., Ltd.) were mixed well, and the mixture was subjected to viscosity adjustment with toluene and applied by spin coating. In this case, the film thickness was adjusted so that it became 1 μm after drying. Thereafter, the sheet was allowed to stand horizontally for 2 hours, the surface was leveled, and toluene as a diluent was evaporated, and further, the sheet was heated at 70 ℃ for 1 hour and then at 150 ℃ for 5 hours by an IR lamp to complete the curing. The refractive index of the uv absorbing layer is about 1.5.

After the ultraviolet absorbing layer was cured, the whole was cooled to room temperature, and bonded to an aluminum alloy frame having the same shape as the outer shape of the substrate, and the substrate was gradually peeled off while removing the electric charge, to obtain the dustproof film of the present invention. The ultraviolet absorbing layer of the obtained dustproof film of the invention is adhered to the adhesive layer, and the dustproof film outside the frame is cut and removed by a cutter, thereby obtaining the dustproof film assembly of the invention. The dustproof film of the dustproof film assembly has an average transmittance of 95.0% in a wavelength region of 350 to 450 nm and an average transmittance of about 35% in a wavelength region of 200 to 300 nm, as measured by a transmittance measuring instrument (manufactured by tsukamur electronic corporation).

[ comparative example ]

A pellicle was produced using the same pellicle frame as that used in example 1. The dust-proof film used in this case was a single-layer film having a thickness of 4 μm and formed only of the cellulose propionate used in example 1. The method for producing the dustproof thin film was the same as that of example 1, except that only the ultraviolet absorption layer forming step was omitted.

In this dustproof film assembly, the light transmittance of the dustproof film was measured by a transmittance measuring instrument (manufactured by tsukamur electronic corporation), and the average transmittance in the wavelength region of 350 to 450 nm was 95.0%. As a result of a light irradiation experiment performed on this pellicle in the same conditions as in example 1, when the cumulative energy became 60 jj, a light, thin, whitish, round irradiation mark occurred in the irradiation portion. Further, it was confirmed that the average transmittance in the wavelength region of 350 to 450 nm was reduced by about 2%, and that the film thickness was calculated from the measurement spectrum, thereby reducing the film thickness at 40 nm.

Industrial applicability of the invention

The pellicle of the present invention is industrially very useful because the light resistance of the pellicle is greatly improved in the photolithography using ultraviolet rays having a wavelength of 350 to 450 nm, although an inexpensive film material such as a cellulose-based resin is used.

Claims

1. A dustproof pellicle used in ultraviolet irradiation lithography in a wavelength range of 350 to 450 nm for a dustproof pellicle assembly, characterized in that the dustproof pellicle is a raw material, and has an ultraviolet absorbing layer on at least the surface on the exposure light source side, and the ultraviolet absorbing layer has a transmittance of 90% or more on average in the wavelength range for ultraviolet rays in the wavelength range of 350 to 450 nm, and has a transmittance of 50% or less on average in the wavelength range for ultraviolet rays in the wavelength range of 200 to 300 nm.

2. The dustproof film as claimed in claim 1, further comprising an anti-reflection layer on the ultraviolet absorbing layer.

3. The dustproof film as claimed in claim 1 or 2, wherein the resin constituting the ultraviolet absorbing layer is a silicone resin.

4. The dustproof film as claimed in any one of claims 1 to 3, wherein the refractive index of the ultraviolet absorbing layer is 1.50 or less.

5. A method for producing a dustproof thin film having an ultraviolet absorbing layer and an anti-reflection layer, wherein a raw dustproof thin film, an ultraviolet absorbing layer and 3 layers of the anti-reflection layer are arranged in an arbitrary order on a film-forming substrate, and then the film-forming substrate is peeled off, characterized in that the layers are formed in order by applying a material solution corresponding to each layer, drying and curing the material solution, wherein the ultraviolet absorbing layer has a transmittance of 90% or more on average in the wavelength range of 350 to 450 nm in ultraviolet rays and has a transmittance of 50% or less on average in the wavelength range of 200 to 300 nm in ultraviolet rays.

6. A pellicle, characterized in that a pellicle manufactured by the method of claim 5 is applied taut over a pellicle frame.

7. A pellicle, characterized in that the pellicle of any of claims 1 to 4 is applied taut over a pellicle frame.