Pellicle frame, pellicle, exposure original plate with pellicle and exposure method, and method for manufacturing semiconductor device or liquid crystal display board

Abstract

To provide a pellicle frame that prevents scattered light derived from the frame and ensures easy inspection of foreign matter adhered to the frame surface, and can also provide a pellicle, an exposure original plate with a pellicle and an exposure method, and a method for manufacturing a semiconductor device or a liquid crystal display board.SOLUTION: A frame-shaped pellicle frame includes an upper end surface on which a pellicle film is provided and a lower end surface facing a photomask. The inner surface of the pellicle frame includes a region where a roughness curve kurtosis (Rku) is 3.0 or less. There are also provided a pellicle, an exposure original plate with a pellicle and an exposure method, and a method for manufacturing a semiconductor device or a liquid crystal display board.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pellicle frame, a pellicle, a photomask with a pellicle, an exposure method, and a method for manufacturing a semiconductor device or a liquid crystal display panel, which are mounted on a photomask for lithography for dust removal.

Background Art

[0002] In recent years, the design rules of LSIs have been miniaturized to sub-quarter microns, and accordingly, the short-wavelength of the exposure light source has been progressing. That is, the exposure light source has shifted from g-line (436 nm) and i-line (365 nm) by a mercury lamp to KrF excimer laser (248 nm), ArF excimer laser (193 nm), etc., and further, EUV (Extreme Ultra Violet) light with a main wavelength of 13.5 nm is used for EUV exposure.

[0003] In the manufacture of semiconductors such as LSIs and super LSIs or the manufacture of liquid crystal display panels, light is irradiated onto a semiconductor wafer or a master for liquid crystal to form a pattern. In this case, if dust adheres to the photomask for lithography and the reticle (hereinafter, collectively referred to as the "exposure master"), the dust absorbs or bends the light, resulting in deformation of the transferred pattern, rough edges, and blackening and soiling of the substrate, which causes problems such as deterioration of dimensions, quality, appearance, etc.

[0004] These operations are usually performed in a clean room, but it is still difficult to always keep the exposure master clean. Therefore, a method of performing exposure after attaching a pellicle to the surface of the exposure master for dust removal is generally adopted. In this case, foreign substances do not directly adhere to the surface of the exposure master but adhere to the pellicle. Therefore, if the focus is adjusted on the pattern of the exposure master during lithography, the foreign substances on the pellicle are irrelevant to the transfer.

[0005] The basic structure of this pellicle is such that a pellicle film with high transmittance to the light used for exposure is stretched on the upper end surface of a pellicle frame made of aluminum, titanium, etc., and an airtight gasket is formed on the lower end surface. An adhesive layer is generally used for the airtight gasket, and a protective sheet for protecting this adhesive layer is attached. The pellicle film is made of nitrocellulose, cellulose acetate, fluorine-based polymers, etc., which transmit well the light used for exposure (such as g-line (436 nm), i-line (365 nm), KrF excimer laser (248 nm), ArF excimer laser (193 nm) by a mercury lamp). For EUV exposure, ultrathin silicon films or carbon films are being studied as the pellicle film.

[0006] Since the purpose of the pellicle is to protect the exposure original plate from the attachment of foreign substances, a very high cleanliness is required for the pellicle. Therefore, in the manufacturing process of the pellicle, it is necessary to inspect whether foreign substances are attached to the pellicle film, pellicle frame, adhesive, and protective sheet before shipment.

[0007] Normally, for the inspection of foreign substances on the pellicle frame, light is focused on the frame in a dark room, and the scattered light from the foreign substances is detected visually. Alternatively, using a foreign substance inspection device, a He-Ne laser or a semiconductor laser is irradiated on the pellicle frame, and the scattered light from the foreign substances is detected by a semiconductor detector (CCD), etc.

[0008] In Patent Document 1, it has been proposed to improve the inspectability by reducing the reflectance of the inspection light on the inner surface of the frame. However, even if the reflectance is reduced, the concave or convex portions present on the frame surface may generate scattered light, and there is a problem that it is difficult to determine whether the detected scattered light is derived from foreign substances or from the frame.

[0009] In addition, since EUV exposure is performed under high vacuum, the EUV pellicle is exposed to pressure changes from atmospheric pressure to vacuum and from vacuum to atmospheric pressure. At this time, air movement occurs through the vent provided in the pellicle frame. In the EUV pellicle, air movement inside the pellicle, which does not exist in the ArF pellicle, occurs, so there is a high risk that foreign matter adhering to the surface of the pellicle frame will fall onto the exposure reticle. Therefore, for EUV pellicles, stricter foreign matter inspection than for ArF pellicles is required.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0011] The present invention has been made in view of the above circumstances, and an object thereof is to provide a pellicle frame, a pellicle, an exposure reticle with a pellicle, an exposure method, and a method for manufacturing a semiconductor device or a liquid crystal display panel that can prevent scattered light derived from the frame and reliably and easily detect foreign matter adhering to the surface of the frame.

Means for Solving the Problems

[0012] The inventor has found that by performing a surface treatment on a frame-shaped pellicle frame having an upper end surface provided with a pellicle film and a lower end surface facing a photomask such that a region having a kurtosis (Rku) of the roughness curve of 3.0 or less is provided on the inner surface of the pellicle frame, it is possible to suppress sharp portions on the surface of the pellicle frame and to inspect minute foreign matters on the surface of the pellicle frame. Generally, the surface roughness of a pellicle frame is indicated by an arithmetic mean roughness Ra. However, even if Ra is simply reduced, the inspectability may be poor. The inventor has focused on kurtosis (Rku) as an index of the above surface roughness, and as a result, has found that foreign matters on the surface of the pellicle frame can be reliably and easily detected, leading to the completion of the present invention.

[0013] Accordingly, the present invention provides the following pellicle frame, pellicle, photomask original plate with pellicle, exposure method, and method for manufacturing a semiconductor device or a liquid crystal display panel. 1. A frame-shaped pellicle frame having an upper end surface provided with a pellicle film and a lower end surface facing a photomask, wherein the inner surface of the pellicle frame has a region having a kurtosis (Rku) of the roughness curve of 3.0 or less. 2. The pellicle frame according to the above 1, wherein the region having a kurtosis (Rku) of the roughness curve of 3.0 or less is the entire region of the inner surface of the pellicle frame or the entire region of the surface of the pellicle frame. 3. The pellicle frame according to the above 1 or 2, wherein the kurtosis (Rku) of the roughness curve is 0.1 or more. 4. The pellicle frame according to the above 1 or 2, wherein the average roughness (Ra) is in the range of 0.001 to 1.0 on at least a part of the inner surface of the pellicle frame. 5. The pellicle frame according to the above 1 or 2, wherein the root mean square height (Rq) is in the range of 0.001 to 1.0 on at least a part of the inner surface of the pellicle frame. 6. The pellicle frame according to the above 1 or 2, wherein the reflectance with respect to inspection light is 20% or less. 7. The pellicle frame according to claim 6, wherein the wavelength of the inspection light is 550 nm. 8. The pellicle frame according to claim 1 or 2, wherein the material of the pellicle frame is selected from the group consisting of titanium, titanium alloy, aluminum, and aluminum alloy. 9. The pellicle frame according to claim 1 or 2, wherein the thickness of the pellicle frame is less than 2.5 mm. 10. The pellicle frame according to claim 1 or 2, wherein the thickness of the pellicle frame is 1.0 mm or more. 11. The pellicle frame according to claim 1 or 2, wherein an oxide film is formed on the surface of the pellicle frame. 12. The pellicle frame according to claim 1 or 2, wherein the surface of the pellicle frame is blackened. 13. The pellicle frame according to claim 1 or 2, wherein physical polishing or chemical polishing is performed on the surface of the pellicle frame. 14. The pellicle frame according to claim 1 or 2, which is a pellicle frame used for an EUV pellicle. 15. A pellicle comprising the pellicle frame according to claim 1 and a pellicle film provided on one end face of the pellicle frame via an adhesive or an adhesive. 16. The pellicle according to claim 15, wherein the pellicle film is provided on the upper end face of the pellicle frame. 17. The pellicle according to claim 15 or 16, wherein the pellicle film is a silicon film or a carbon film. 18. The pellicle according to claim 15 or 16, wherein the height of the pellicle is 2.5 mm or less. 19. The pellicle according to claim 15 or 16, which is used for exposure under vacuum or reduced pressure. 20. The pellicle according to claim 15 or 16, which is used for EUV exposure. 21. An exposure original plate with a pellicle, characterized in that the pellicle according to claim 15 is mounted on the exposure original plate. 22. The exposure original plate with a pellicle according to claim 21, wherein the exposure original plate is an exposure original plate for EUV. 23. The exposure original plate with a pellicle according to claim 21, which is an exposure original plate with a pellicle used for EUV lithography. 24. An exposure method characterized in that exposure is performed using the exposed original plate with a pellicle described in 21 above. 25. The exposure method described in 24 above, wherein the exposure light source is an exposure light source that emits EUV light. 26. A method for manufacturing a semiconductor device, comprising a step of exposing a substrate under vacuum or reduced pressure using the exposed original plate with a pellicle described in 21 above. 27. The method for manufacturing a semiconductor device described in 26 above, wherein the exposure light source is an exposure light source that emits EUV light. 28. A method for manufacturing a liquid crystal display panel, comprising a step of exposing a substrate under vacuum or reduced pressure using the exposed original plate with a pellicle described in 21 above. 29. The method for manufacturing a liquid crystal display panel described in 28 above, wherein the exposure light source is an exposure light source that emits EUV light.

Advantages of the Invention

[0014] The pellicle frame and pellicle of the present invention can prevent scattered light derived from the frame and can reliably and easily detect foreign matter attached to the surface of the frame, and can provide a pellicle frame and pellicle with good inspectability. Further, by using the above-mentioned pellicle, it is very useful in a method for manufacturing a semiconductor device or a liquid crystal display panel including a step of exposing a substrate using an exposed original plate with a pellicle.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0016] Hereinafter, the present invention will be described in more detail. The pellicle frame of the present invention is a frame-shaped pellicle frame having an upper end surface on which a pellicle film is provided and a lower end surface facing a photomask.

[0017] If the pellicle frame is in a frame shape, its shape corresponds to the shape of the photomask to which the pellicle is attached. Generally, it is in a rectangular (rectangular or square) frame shape. In addition to the rectangular frame shape, it can be changed to a polygonal frame shape such as a triangular frame shape, a pentagonal frame shape, a hexagonal frame shape, an octagonal frame shape, etc., or a circular frame shape, an elliptical frame shape, etc., corresponding to the shape of the photomask. Regarding the shape of the corner part (edge part) of the pellicle frame, it may be in a sharp (pointed) shape as it is, or it may be chamfered such as R chamfering or C chamfering, or other shapes such as a curved shape.

[0018] In addition, the pellicle frame has a surface for providing the pellicle film (here, the upper end surface), and a surface facing the photomask when the photomask is attached (here, the lower end surface).

[0019] Normally, a pellicle film is provided on the upper end surface of the pellicle frame via an adhesive or the like, and an adhesive or the like for attaching the pellicle to the photomask is provided on the lower end surface, but this is not the only case.

[0020] There is no limitation on the material of the pellicle frame, and known materials can be used. For a pellicle frame for EUV, since it may be exposed to high temperatures, a material with a small coefficient of thermal expansion is preferred. For example, Si, SiO2, SiN, quartz, invar, titanium, titanium alloy, aluminum, aluminum alloy, etc. can be mentioned. Among them, it is preferably selected from the group consisting of titanium, titanium alloy, aluminum, and aluminum alloy because of easy processability and light weight. Also, from the viewpoint of low coefficient of thermal expansion, it is preferably selected from titanium or titanium alloy.

[0021] The dimensions of the pellicle frame are not particularly limited. However, when the height of the EUV pellicle is limited to 2.5 mm or less, the thickness of the EUV pellicle frame is preferably smaller than that and less than 2.5 mm. In particular, considering the thicknesses of the pellicle film, mask adhesive, etc., the thickness of the EUV pellicle frame is preferably 1.5 mm or less. Also, the lower limit value of the thickness of the above-mentioned pellicle frame is preferably 1.0 mm or more.

[0022] In the pellicle frame of the present invention, for example, on the inner surface of the pellicle frame, the surface treatment of the pellicle frame is performed so as to have a region where the kurtosis (Rku) of the roughness curve is 3.0 or less. There is no particular limitation on the method of this surface treatment, and physical polishing (manual metal polishing, buff polishing, mechanochemical polishing, blasting treatment, etc.) or chemical polishing (chemical polishing, electrolytic polishing, etc.) can be used, and these polishing methods can also be combined. In these polishing methods, it is possible to adjust the value of Rku by appropriately changing polishing conditions such as the type of abrasive, the particle size of the abrasive, and the polishing time. Also, in the present invention, it is sufficient that a region where the kurtosis (Rku) of the roughness curve is 3.0 or less is present in a part of the inner surface of the pellicle frame. From the viewpoint of manufacturing efficiency, preferably, the surface treatment can be performed on the entire inner surface, more preferably, the Rku value is 3.0 or less on the entire surface of the frame (that is, the upper end surface, the lower end surface, the inner surface, and the outer surface of the frame). In this case, the pellicle frame may not be partially surface-treated.

[0023] Also, in the present invention, regarding the above-mentioned kurtosis (Rku), it is 3.0 or less, preferably 2.9 or less, more preferably 2.8 or less, and particularly preferably 2.7 or less. The lower limit value is not particularly limited, but is preferably 0.1 or more, and more preferably 0.5 or more.

[0024] The measurement method of kurtosis (Rku) is defined by JIS B 0601:2013. Kurtosis (Rku) means the sharpness, which is a measure of the sharpness of the surface, and represents the sharpness (pointiness) of the height distribution. When the value of kurtosis (Rku) is 3.0, it indicates a normal distribution. When it is greater than 3.0, the height distribution is sharp, and when it is less than 3.0, it means that the height distribution of the surface unevenness is flattened.

[0025] Kurtosis (Rku) is calculated by the following formula. That is, kurtosis (Rku) is the fourth-order mean value of Z(x) at the reference length dimensionless by the fourth power of Rq (root mean square roughness) of the roughness curve, and is strongly affected by the protruding peaks or valleys of the surface unevenness.

Equation

[0026] As the above measurement method of kurtosis (Rku), for example, a commercially available 3D measurement laser microscope can be used, and kurtosis (Rku) can be measured from the measurement cross-sectional curve obtained by this measuring instrument. Examples of such measuring instruments include the product name "LEST OLS4000" (manufactured by Olympus Corporation) and the product name "VK-X1000" (manufactured by Keyence Corporation).

[0027] In addition, as indicators of surface roughness other than the above kurtosis (Rku), average roughness (Ra) and root mean square height (Rq) are mentioned. Although there is no particular limitation in the present invention, in at least a part of the inner surface of the pericle frame, it is preferable that Ra is in the range of 0.001 to 1.0, and it is also preferable that Rq is in the range of 0.001 to 1.0. The values of Ra and Rq can also be measured according to the provisions of JIS B 0601:2013, and can be measured by measuring instruments such as the product name "LEST OLS4000" (manufactured by Olympus Corporation) and the product name "VK-X1000" (manufactured by Keyence Corporation).

[0028] Further, in order to further improve the inspectability, the frame may be colored to reduce the reflectivity with respect to the inspection light. In that case, it is preferable that the reflectivity with respect to the inspection light is 20% or less. There is no limitation on the coloring method, but it is preferable to form an oxide film on the surface by anodization or the like and cause color development by the color of interference because the addition of other substances is unnecessary.

[0029] Also, usually, jig holes used when handling or peeling the pellicle from the photomask are provided on the side surface of the pellicle frame. The size of the jig hole means the length in the thickness direction of the pellicle frame (diameter in the case of a circle), and is preferably 0.5 to 1.0 mm. There is no limitation on the shape of the hole, and it may be circular or rectangular.

[0030] Further, the pellicle frame may be provided with a ventilation portion, and a filter may be provided in the ventilation portion to prevent the intrusion of foreign matters. In addition, an inorganic film or an organic film may be provided on the surface of the pellicle frame (that is, any part of the upper end surface, lower end surface, inner side surface, and outer side surface of the frame).

[0031] In the pellicle of the present invention, a pellicle film is provided on the upper end surface of the pellicle frame via an adhesive or an adhesive. There is no limitation on the material of the adhesive or the adhesive, and known ones can be used. In order to strongly hold the pellicle film, an adhesive or an adhesive having a strong adhesive force is preferable.

[0032] Regarding the material of the above-mentioned pellicle film, there is no particular limitation, but those having a high transmittance at the wavelength of the exposure light source and high light resistance are preferable. For example, for EUV exposure, an ultrathin silicon film, a carbon film, or the like is used. Examples of these carbon films include films such as graphene, diamond-like carbon, and carbon nanotubes. The above-mentioned pellicle film is not limited to only a thin film, and those including a support frame for supporting the pellicle film can also be adopted. For example, a method of forming a pellicle film on a silicon wafer and removing the silicon wafer by back etching only at the location used as the pellicle film can be adopted. In this case, the pellicle film can be obtained in a state supported by a silicon frame.

[0033] Furthermore, a mask adhesive for attaching to a photomask is formed on the lower end surface of the pellicle frame. Generally, it is preferable that the mask adhesive is provided over the entire circumference of the pellicle frame.

[0034] As the above mask adhesive, known ones can be used, and acrylic adhesives and silicone adhesives can be preferably used. The adhesive may be processed into any shape as required.

[0035] A release layer (separator) for protecting the adhesive may be attached to the lower end surface of the above mask adhesive. The material of the release layer is not particularly limited. For example, polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polyethylene (PE), polycarbonate (PC), polyvinyl chloride (PVC), polypropylene (PP), etc. can be used. Also, if necessary, a release agent such as a silicone-based release agent or a fluorine-based release agent may be applied to the surface of the release layer. Note that the attachment of the pellicle to the photomask can also be fixed by physical fixing means other than the mask adhesive. Examples of such fixing means include screws, bolts, nuts, rivets, keys, pins, etc. It is also possible to use the mask adhesive and physical fixing means in combination.

[0036] Here, FIG. 1 shows an example of the pellicle frame 1 of the present invention, reference numeral 11 indicates the inner surface of the pellicle frame, reference numeral 12 indicates the outer surface of the pellicle frame, reference numeral 13 indicates the upper end surface of the pellicle frame, and reference numeral 14 indicates the lower end surface of the pellicle frame. Usually, a jig hole used for peeling the pellicle from the photomask is provided on the long side of the pellicle frame, but it is not particularly shown in FIG. 1.

[0037] Figure 2 shows the pellicle 10. A pellicle film 2 is adhered and stretched on the upper end surface of the pellicle frame 1 by an adhesive 4. Also, on the lower end surface of the pellicle frame 1, it is detachably adhered to a photomask 3 by an adhesive 5, protecting the pattern surface on the photomask 3.

[0038] The pellicle of the present invention can be used not only as a protection member for suppressing the adhesion of foreign substances to the exposure original plate in an EUV exposure apparatus, but also as a protection member for protecting the exposure original plate during storage and transportation of the exposure original plate. Methods for attaching a pellicle to an exposure original plate such as a photomask and manufacturing an exposure original plate with a pellicle include, in addition to the method of attaching with the aforementioned mask adhesive, an electrostatic adsorption method, a method of mechanically fixing, and the like.

[0039] The method for manufacturing a semiconductor device or a liquid crystal display panel according to this embodiment includes a step of exposing a substrate (semiconductor wafer or original plate for liquid crystal) with the above-described exposure original plate with a pellicle. For example, in a lithography process which is one of the manufacturing processes of a semiconductor device or a liquid crystal display panel, in order to form a photoresist pattern corresponding to an integrated circuit or the like on a substrate, the above-described exposure original plate with a pellicle is installed on a stepper and exposed. Generally, in EUV exposure, a projection optical system in which EUV light is reflected by the exposure original plate and guided to the substrate is used, and these are performed under reduced pressure or in a vacuum. Thereby, even if foreign substances adhere to the pellicle in the lithography process, these foreign substances do not form an image on the wafer coated with the photoresist, so that short circuits or disconnections of integrated circuits or the like due to the images of the foreign substances can be prevented. Therefore, by using the exposure original plate with a pellicle, the yield in the lithography process can be improved.

Example

[0040] Hereinafter, examples and comparative examples will be shown to specifically explain the present invention, but the present invention is not limited to the following examples.

[0041] [Example 1] A titanium pellicle frame (outer dimensions 150 mm × 118 mm × 1.5 mm, frame width 4.0 mm) was fabricated. After removing the processing scratches on the surface of the titanium frame (the entire surface of the upper end face, lower end face, inner side face, and outer side face of the frame) with sandpaper (grit size 1,000), it was polished manually with metal polishing powder (Picard solution manufactured by Nippon Polishing Industry Co., Ltd.). This pellicle frame was cleaned by ultrasonic cleaning with pure water and a neutral detergent. On the upper end face of the frame, a material obtained by adding 1 part by mass of a curing agent (PT-56 manufactured by Shin-Etsu Chemical Co., Ltd.) to 100 parts by mass of a silicone adhesive (X-40-3264 manufactured by Shin-Etsu Chemical Co., Ltd.) as a pellicle film adhesive and stirring was applied to a width of 1 mm and a thickness of 0.1 mm. Also, on the lower end face of the frame, a material obtained by adding 0.1 part by mass of a curing agent (L-45 manufactured by Soken Chemical & Engineering Co., Ltd.) to 100 parts by mass of an acrylic adhesive (SK Dyn 1495 manufactured by Soken Chemical & Engineering Co., Ltd.) as a mask adhesive and stirring was applied over the entire circumference to a width of 1 mm and a thickness of 0.1 mm. Thereafter, the pellicle frame was heated at 90 °C for 12 hours to cure the pellicle film adhesive and mask adhesive on the upper and lower end faces. Subsequently, an ultrathin silicon film was used as the pellicle film and was pressure-bonded to the pellicle film adhesive formed on the upper end face of the frame to complete the pellicle.

[0042] [Example 2] After fabricating a titanium frame, a blasting treatment was performed using a sandblasting apparatus instead of removing the processing scratches on the surface with sandpaper, and a chemical polishing treatment was performed instead of polishing with metal polishing powder. A pellicle was completed in the same manner as in Example 1. The sandblasting conditions and chemical polishing treatment conditions used here are as follows. 〈Sandblasting Conditions〉 · Abrasive: Glass beads (center particle size ≤ 30 μm) manufactured by Fuji Seisakusho Co., Ltd. · Discharge pressure: 7 kgf / cm 2 · Time: 30 seconds 〈Chemical Polishing Treatment Conditions〉 · Chemical solution: “Esclean S-22” manufactured by Sasaki Chemical Co., Ltd. · Temperature: 30 °C · Treatment time: 10 seconds

[0043] [Example 3] A pellicle was completed in the same manner as in Example 2, except that it was colored purple by anodization following the chemical polishing treatment.

[0044] [Example 4] A pellicle frame made of an aluminum alloy was produced instead of the titanium-made pellicle frame. A blasting treatment under the same conditions as in Example 2 was performed instead of removing the processing scratches on the surface with sandpaper. A pellicle was completed in the same manner as in Example 1, except that an anodic oxidation, black dyeing, and sealing treatment were performed instead of polishing with metal polishing powder to form a black oxide film on the surface.

[0045] [Comparative Example 1] A blasting treatment under the same conditions as in Example 2 was performed instead of removing the processing scratches on the surface with sandpaper. A pellicle was completed in the same manner as in Example 1, except that it was colored purple by anodization instead of polishing with metal polishing powder.

[0046] [Comparative Example 2] A pellicle was completed in the same manner as in Example 1, except that a chemical polishing treatment under the same conditions as in Example 2 was performed instead of polishing with metal polishing powder.

[0047] Visual inspection and surface roughness measurement were performed on the pellicles obtained in Examples 1 to 4 and Comparative Examples 1 and 2. Also, using the same frame materials as in Examples 1 to 4 and Comparative Examples 1 and 2, and using sample pieces with the surface treatment applied to the materials, the reflectance of each sample was measured.

[0048] [Reflectance Measurement] A 3 cm × 3 cm sample piece with a thickness of 5 mm was prepared, and the same surface treatment as in Examples 1 to 4 and Comparative Examples 1 and 2 was applied to prepare a sample. Using a "Spectrophotometer V-780" (manufactured by JASCO Corporation, model name), the reflectance at 550 nm was measured.

[0049] [Surface Roughness Measurement] At the four central points (reference signs P, P, P, and P in Fig. 1) on the inner side surfaces of each side of the frame of the pellicle in each example, the arithmetic mean roughness Ra, the root mean square height Rq, and the kurtosis (Rku) were measured under the following conditions using a 3D measurement laser microscope "LEXT OLS4000" (manufactured by Olympus Corporation, model name). < LEXT OLS4000 measurement conditions> · Evaluation length: 4 mm · Cutoff: λc 800 μm, λs 2.5 μm, λf none · Filter: Gaussian filter · Analysis parameter: Roughness parameter · Objective lens: ×50

[0050] [Visual inspection] Standard particles of 20 μm were attached to a part of the inner wall surface of the obtained pellicle, and while irradiating with a condenser lamp in a dark room, the quality of the detectability of foreign matters was evaluated according to the following criteria. 〈Judgment criteria〉 〇: No scattered light was confirmed in the part where the particles were not attached, and scattered light was confirmed only in the part where the particles were attached. ×: Scattered light was confirmed even in the part where the particles were not attached.

[0051]

Table 1

[0052] The following points can be considered from the results in Table 1 above. Although the pellicle frames of Comparative Example 1 and Comparative Example 2 have low reflectivity or a small arithmetic mean roughness Ra, the kurtosis (Rku) exceeds 3. As a result, it can be seen that the visual foreign matter detectability is poor. On the other hand, for the pellicle frames of Examples 1 to 4 in which the kurtosis (Rku) of the frame surface is 3 or less, it can be seen that the visual foreign matter detectability is good regardless of the magnitudes of the values of Ra and Rq, which are other height parameters of the reflectivity and roughness curve.

Explanation of reference signs

[0053] 1 Pericle Frame 2 Pericle Film 3 Photo Mask 4 Pericle Film Adhesive 5 Mask Adhesive 10 Pericle Center Part of the Inner Surface of P

Claims

【Claim 1】 A frame-shaped pellicle frame having an upper end face provided with a pellicle film and a lower end face facing a photomask, wherein an inner surface of the pellicle frame has a region where the kurtosis (Rku) of the roughness curve is 3.0 or less. The pellicle frame is characterized by this.

Images