Protective film frame, protective film assembly, and applications of protective film assemblies

Abstract

The present application provides a protective film frame, a protective film assembly and applications thereof, an exposure original plate with a protective film assembly and an exposure method, and a manufacturing method of a semiconductor device or a liquid crystal display panel. The protective film frame is a frame-shaped protective film frame having an upper end surface on which a protective film is provided and a lower end surface facing a photomask, wherein: an area having a roughness curve kurtosis (Rku) of 3.0 or less is present on an inner side surface of the protective film frame. The present application can provide a protective film frame and a protective film assembly using the same, which prevent scattered light originating from the frame and make it easy to check foreign matter attached to the surface of the frame.

Description

Technical Field

[0001] This invention relates to a protective film frame (pellicle frame) installed on a photomask for lithography as a dust collector, a protective film assembly (pellicle) and its application, an exposure master with a protective film assembly and an exposure method, and a method for manufacturing a semiconductor device or a liquid crystal display panel. Background Technology

[0002] In recent years, the design rules for Large Scale Integrated Circuits (LSI) have been advancing towards miniaturization down to the sub-quarter micron level, accompanied by a trend towards shorter wavelengths of exposure light sources. Specifically, exposure light sources have shifted from mercury lamp-based gamma rays (436 nm) and i-rays (365 nm) to KrF excimer lasers (248 nm) and ArF excimer lasers (193 nm), and further, research has been conducted on EUV exposure using extreme ultraviolet (EUV) light with a dominant wavelength of 13.5 nm.

[0003] In the manufacturing of semiconductors such as LSI and super LSI, or liquid crystal display panels, patterns are created by irradiating light onto semiconductor wafers or liquid crystal substrates. If dust adheres to the photomask and reticles (hereinafter collectively referred to as "exposure originals") used in this process, the dust will absorb light or bend the light, resulting in distorted transferred patterns or rough edges. In addition, there are problems such as the substrate being stained black, and damage to size, quality, and appearance.

[0004] These operations are typically performed in a clean room, but even then, it's difficult to keep the exposure master completely clean. Therefore, a common method is to attach a protective film assembly as a dust collector to the surface of the exposure master before exposure. In this case, foreign matter does not adhere directly to the surface of the exposure master, but rather to the protective film assembly. Therefore, if the focus is on the pattern on the exposure master during photolithography, foreign matter on the protective film assembly becomes irrelevant to the transfer process.

[0005] The basic structure of the protective film assembly is as follows: a protective film with high transmittance relative to the light used in the exposure is stretched on the upper surface of a protective film frame containing aluminum or titanium, and an airtight gasket is formed on the lower surface. The airtight gasket typically uses an adhesive layer and is covered with a protective sheet for protecting the adhesive layer. The protective film contains nitrocellulose, cellulose acetate, fluoropolymers, etc., which allow good transmission of the light used in the exposure (gamma rays (436 nm), i rays (365 nm), KrF excimer lasers (248 nm), ArF excimer lasers (193 nm), etc.) based on mercury lamps; however, for EUV exposure applications, ultrathin silicon or carbon films are being researched as protective films.

[0006] The purpose of the protective film assembly is to protect the exposure original from foreign matter adhering to it; therefore, a very high level of cleanliness is required for the protective film assembly. Consequently, during the manufacturing process of the protective film assembly, it is necessary to inspect the protective film, protective film frame, adhesive, and protective sheet for foreign matter before shipment.

[0007] Typically, foreign object inspection of a protective film frame involves shining a focused light onto the frame in a dark room and visually inspecting the scattered light from the foreign object. Alternatively, a foreign object inspection device can be used to irradiate the protective film frame with a He-Ne laser or a semiconductor laser, and a semiconductor detector (charge-coupled device, CCD) or similar device can be used to detect the scattered light from the foreign object.

[0008] Patent document 1 proposes to improve inspectability by reducing the reflectivity of the inner surface of the frame for inspection light. However, even with reduced reflectivity, recesses or protrusions on the frame surface can sometimes generate scattered light, resulting in the problem that it is difficult to determine whether the detected scattered light originates from a foreign object or from the frame itself.

[0009] Furthermore, since EUV exposure is performed under high vacuum, the EUV protective film assembly is exposed to pressure changes from atmospheric pressure to vacuum and back to atmospheric pressure. During this process, air movement occurs through the vents in the protective film frame. Because of this internal air movement—which is absent in ArF protective film assemblies—foreign matter adhering to the protective film frame surface is at high risk of falling onto the exposed image. Therefore, EUV protective film assemblies require more stringent foreign matter inspection than ArF protective film assemblies.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 2001-249442 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] The present invention was made in view of the above circumstances, and aims to provide a protective film frame that can prevent scattered light from the frame and reliably and easily detect foreign matter attached to the surface of the frame, a protective film assembly, an exposure original and exposure method with the protective film assembly, and a method for manufacturing a semiconductor device or liquid crystal display panel.

[0015] Technical means to solve the problem

[0016] The inventors have achieved the following insight: In a frame-shaped protective film frame having an upper end face with a protective film and a lower end face facing a photomask, the surface of the protective film frame is treated to have a region on the inner surface of the protective film frame with a kurtosis (Rku) of 3.0 or less. As a result, sharp edges on the surface of the protective film frame can be suppressed, and minute foreign objects on the surface of the protective film frame can be inspected. Typically, the surface roughness of a protective film frame is represented by the arithmetic mean roughness Ra, but simply reducing Ra can lead to poor inspection. The inventors have replaced the surface roughness index with kurtosis (Rku), and as a result, found that foreign objects on the surface of the protective film frame can be detected reliably and easily, thus forming the present invention.

[0017] Therefore, the present invention provides the following protective film frame, protective film assembly, exposure master with protective film assembly and exposure method, and method for manufacturing semiconductor device or liquid crystal display panel.

[0018] 1. A protective film frame having a frame-shaped protective film frame having an upper end surface on which a protective film is disposed and a lower end surface facing a photomask, wherein: the inner surface of the protective film frame has a region with a roughness curve kurtosis (Rku) of 3.0 or less.

[0019] 2. The protective film frame according to claim 1, wherein: the area where the kurtosis (Rku) of the roughness curve is 3.0 or less is the entire area of ​​the inner surface of the protective film frame or the entire area of ​​the surface of the protective film frame.

[0020] 3. The protective film frame according to 1 or 2, wherein the kurtosis (Rku) of the roughness curve is 0.1 or more.

[0021] 4. The protective film frame according to 1 or 2, wherein: at least a portion of the inner surface of the protective film frame has an average roughness (Ra) in the range of 0.001 to 1.0.

[0022] 5. The protective film frame according to 1 or 2, wherein: the root mean square height (Rq) of at least a portion of the inner surface of the protective film frame is in the range of 0.001 to 1.0.

[0023] 6. The protective film frame according to 1 or 2, wherein the reflectivity for inspection light is less than 20%.

[0024] 7. The protective film frame according to 6, wherein the wavelength of the inspection light is 550 nm.

[0025] 8. The protective film frame according to 1 or 2, wherein: the material of the protective film frame is selected from the group consisting of titanium, titanium alloys, aluminum and aluminum alloys.

[0026] 9. The protective film frame according to 1 or 2, wherein the thickness of the protective film frame is less than 2.5 mm.

[0027] 10. The protective film frame according to 1 or 2, wherein the thickness of the protective film frame is 1.0 mm or more.

[0028] 11. The protective film frame according to 1 or 2, wherein: an oxide film is formed on the surface of the protective film frame.

[0029] 12. The protective film frame according to 1 or 2, wherein: the surface of the protective film frame is blackened.

[0030] 13. The protective film frame according to 1 or 2, wherein: the surface of the protective film frame is subjected to physical or chemical abrasion.

[0031] 14. The protective film frame according to 1 or 2, which is a protective film frame for a protective film assembly for extreme ultraviolet light.

[0032] 15. A protective film assembly comprising: a protective film frame according to claim 1, and a protective film disposed on one end face of the protective film frame via an adhesive or bonding agent.

[0033] 16. The protective film assembly according to 15, wherein: the protective film is disposed on the upper end face of the protective film frame.

[0034] 17. The protective film assembly according to 15 or 16, wherein: the protective film is a silicon film or a carbon film.

[0035] 18. The protective film assembly according to 15 or 16, wherein the height of the protective film assembly is 2.5 mm or less.

[0036] 19. The protective film assembly described in 15 or 16, used in exposure under vacuum or reduced pressure.

[0037] 20. The protective film assembly described in 15 or 16 is used for extreme ultraviolet light exposure.

[0038] 21. An exposure original with a protective film assembly, wherein: the exposure original is equipped with the protective film assembly as described in 15.

[0039] 22. The exposure master with protective film assembly as described in 21, wherein: the exposure master is an exposure master for extreme ultraviolet light.

[0040] 23. The exposure master of the protective film assembly described in 21 is an exposure master of the protective film assembly for extreme ultraviolet lithography.

[0041] 24. An exposure method, wherein: exposure is performed by means of an exposure master with a protective film assembly as described in 21.

[0042] 25. The exposure method according to 24, wherein: the light source for exposure is an exposure light source that emits extreme ultraviolet light.

[0043] 26. A method for manufacturing a semiconductor device, comprising: a step of exposing a substrate under vacuum or reduced pressure using an exposure template with a protective thin film assembly as described in 21.

[0044] 27. The method for manufacturing a semiconductor device according to 26, wherein: the light source for exposure is an exposure light source that emits extreme ultraviolet light.

[0045] 28. A method for manufacturing a liquid crystal display panel, comprising: a step of exposing a substrate under vacuum or reduced pressure using an exposure master with a protective film assembly as described in 21.

[0046] 29. The method for manufacturing a liquid crystal display panel according to 28, wherein: the light source for exposure is an exposure light source that emits extreme ultraviolet light.

[0047] The effects of the invention

[0048] The protective film frame and protective film assembly of the present invention can prevent scattered light originating from the frame, reliably and easily detect foreign matter adhering to the frame surface, and provide a protective film frame and protective film assembly with good inspection capabilities. Furthermore, the protective film assembly is very useful in manufacturing methods of semiconductor devices or liquid crystal display panels, including processes such as exposing a substrate using an exposure master with a protective film assembly. Attached Figure Description

[0049] Figure 1 This is a perspective view showing an example of the protective film frame of the present invention.

[0050] Figure 2 This is a schematic diagram showing the configuration of the protective film assembly of the present invention mounted on a photomask.

[0051] [Explanation of Symbols]

[0052] 1: Protective film frame

[0053] 2: Protective film

[0054] 3: Photomask

[0055] 4: Protective film adhesive

[0056] 5: Mask adhesive

[0057] 10: Protective film assembly

[0058] 11: Inner side of the protective film frame

[0059] 12: The outer surface of the protective film frame

[0060] 13: Upper surface of the protective film frame

[0061] 14: Lower end face of the protective film frame

[0062] P: The central part of the inner side Detailed Implementation

[0063] The present invention will now be described in more detail.

[0064] The protective film frame of the present invention is a frame-shaped protective film frame having an upper end surface on which the protective film is disposed and a lower end surface facing the photomask.

[0065] If the protective film frame is frame-shaped, its shape corresponds to the shape of the photomask on which the protective film assembly is mounted. It is typically a quadrilateral (rectangular or square) frame. Besides quadrilateral frames, it can also be a polygonal frame (triangular, pentagonal, hexagonal, octagonal, etc.), or a circular or elliptical frame. Regarding the shape of the corners (edges) of the protective film frame, they can remain as they are and have sharp angles, or they can be chamfered (R-shaped or C-shaped) to create curved shapes or other shapes.

[0066] In addition, the protective film frame has a surface for setting the protective film (here, the upper surface) and a surface for facing the photomask when installing the photomask (here, the lower surface).

[0067] Typically, a protective film is applied to the upper surface of the protective film frame via an adhesive or similar agent, and an adhesive or similar agent for mounting the protective film assembly onto a photomask is applied to the lower surface, but this is not the only option.

[0068] There are no restrictions on the material of the protective film frame; existing materials can be used. In protective film frames for EUV applications, since there is a possibility of exposure to high temperatures, materials with a low coefficient of thermal expansion are preferred. Examples include Si, SiO2, SiN, quartz, Invar, titanium, titanium alloys, aluminum, and aluminum alloys. Among these, materials selected from the group consisting of titanium, titanium alloys, aluminum, and aluminum alloys are preferred in terms of ease of processing and lightweight. Furthermore, from the viewpoint of a low coefficient of thermal expansion, materials selected from titanium or titanium alloys are preferred.

[0069] The dimensions of the protective film frame are not particularly limited. However, when the height of the EUV protective film assembly is limited to 2.5 mm or less, the thickness of the EUV protective film frame is preferably smaller than 2.5 mm. In particular, considering the thickness of the protective film or mask adhesive, the thickness of the EUV protective film frame is preferably 1.5 mm or less. Furthermore, the lower limit of the thickness of the protective film frame is preferably 1.0 mm or more.

[0070] In the protective film frame of the present invention, for example, a surface treatment is performed on the protective film frame so that the inner surface of the protective film frame has a region with a kurtosis (Rku) of 3.0 or less. There are no particular limitations on the method of surface treatment; physical grinding (metal polishing based on manual operations, polishing grinding, mechanical chemical grinding, blasting, etc.) or chemical grinding (chemical grinding or electrolytic grinding, etc.) can be used, or these grinding methods can be combined. In these grinding methods, the value of Rku can be adjusted by appropriately changing grinding conditions such as the type of abrasive material, the particle size of the abrasive material, and the grinding time. Furthermore, in the present invention, the region with a kurtosis (Rku) of 3.0 or less only needs to exist in a portion of the inner surface of the protective film frame. From the viewpoint of manufacturing efficiency, the protective film frame can be surface treated so that the Rku value is preferably set to 3.0 or less in all of the inner surface, and more preferably in all of the frame surface (i.e., all surfaces of the upper end face, lower end face, inner surface, and outer surface of the frame). In this case, surface treatment may also be omitted in certain areas of the protective film frame.

[0071] Furthermore, in this invention, the kurtosis (Rku) is 3.0 or less, preferably 2.9 or less, more preferably 2.8 or less, and particularly preferably 2.7 or less. There are no particular limitations on the lower limit value, but it is preferably 0.1 or more, more preferably 0.5 or more.

[0072] The method for measuring kurtosis (Rku) is specified by Japanese Industrial Standards (JIS) B 0601:2013. Kurtosis (Rku) is a measure of surface sharpness, representing the peak shape (sharpness) of the height distribution. A kurtosis (Rku) value of 3.0 indicates a normal distribution; a value greater than 3.0 indicates a sharp height distribution; and a value less than 3.0 indicates a rounded height distribution with uneven surfaces.

[0073] Kurtosis (Rku) is calculated according to the following formula. That is, kurtosis (Rku) is the average of the fourth power of Z(x) in the reference length obtained by dimensionless transformation of the fourth power of Rq (root mean square roughness) of the roughness curve, and is strongly affected by the prominent peaks or valleys of the surface unevenness.

[0074] [Formula 1]

[0075]

[0076] (Rq: root mean square roughness, l: reference length)

[0077] As a method for measuring the kurtosis (Rku), for example, a commercially available three-dimensional (3D) laser microscope can be used, and the kurtosis (Rku) can be measured using the measurement profile curve obtained by the measuring machine. Examples of such measuring machines include the product name "LEST OLS4000" (manufactured by Olympus) or the product name "VK-X1000" (manufactured by Keyence).

[0078] In addition to the kurtosis (Rku), other indicators of surface roughness include average roughness (Ra) and root mean square height (Rq). In this invention, there are no particular limitations; for at least a portion of the inner surface of the protective film frame, Ra is preferably in the range of 0.001 to 1.0, and Rq is preferably in the range of 0.001 to 1.0. These values ​​of Ra and Rq can also be measured according to JIS B 0601:2013 using a measuring instrument such as the "LEST OLS4000" (manufactured by Olympus) or the "VK-X1000" (manufactured by Keyence).

[0079] Furthermore, to further improve inspectability, the frame can be colored to reduce the reflectivity to inspection light. In this case, the reflectivity to inspection light is preferably 20% or less. The coloring method is not limited; since no other substances need to be added, it is preferable to form an oxide film on the surface by anodizing or the like, and then make it visible through interference colors.

[0080] Additionally, clamping holes are typically provided on the side of the protective film frame for handling or peeling the protective film assembly from the photomask. The size of the clamping hole refers to the length (or diameter if circular) of the protective film frame in the thickness direction, preferably 0.5 mm to 1.0 mm. The shape of the hole is not limited and can be circular or rectangular.

[0081] Additionally, a ventilator can be provided in the protective film frame, and a filter can be installed to prevent foreign objects from entering the ventilator. Furthermore, an inorganic or organic membrane can also be provided on the surface of the protective film frame (i.e., any part of the upper, lower, inner, and outer surfaces of the frame).

[0082] The protective film assembly of the present invention provides a protective film on the upper surface of a protective film frame via an adhesive or bonding agent. The material of the adhesive or bonding agent is not limited and existing materials can be used. For strong adhesion of the protective film, an adhesive or bonding agent with high bonding strength is preferred.

[0083] There are no particular limitations on the material of the protective film, but materials with high transmittance and high lightfastness at the wavelength of the exposure light source are preferred. For example, extremely thin silicon films or carbon films are used for EUV exposure. Examples of such carbon films include graphene, diamond-like carbon, and carbon nanotubes. The protective film is not limited to a thin film; it can also be a film including a support frame for supporting the protective film. For example, the protective film can be fabricated by forming it on a silicon wafer and then removing the silicon wafer by back-side etching only the area used as the protective film. In this case, the protective film can be obtained while supported by a silicon frame.

[0084] Furthermore, a mask adhesive for mounting on the photomask is formed on the lower end face of the protective film frame. Typically, the mask adhesive is preferably applied throughout the entire circumference of the protective film frame.

[0085] As the mask adhesive, existing adhesives can be used, and acrylic or silicone adhesives may be suitable. The adhesive can also be processed into any shape as needed.

[0086] A release layer (separator) for protecting the adhesive can also be attached to the lower surface of the 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), and polypropylene (PP) can be used. Alternatively, a silicone-based or fluorine-based release agent can be coated on the surface of the release layer as needed. Furthermore, regarding the installation of the protective film assembly onto the photomask, in addition to using the mask adhesive, physical fixing methods can also be used. Examples of such fixing methods include screws, bolts, nuts, rivets, keys, and pins. The mask adhesive and physical fixing methods can also be used in combination.

[0087] Here, Figure 1 An example of the protective film frame 1 of the present invention is shown, where symbol 11 denotes the inner surface of the protective film frame, symbol 12 denotes the outer surface of the protective film frame, symbol 13 denotes the upper end surface of the protective film frame, and symbol 14 denotes the lower end surface of the protective film frame. Furthermore, typically, a clamping hole for peeling the protective film assembly from the photomask is provided on the long side of the protective film frame, but... Figure 1 The diagram is not specifically provided.

[0088] Figure 2 This diagram shows the protective film assembly 10, in which the protective film 2 is bonded and stretched onto the upper surface of the protective film frame 1 using adhesive 4. Additionally, on the lower surface of the protective film frame 1, an adhesive 5 is used to peelably bond it to the photomask 3, protecting the patterned surface on the photomask 3.

[0089] The protective film assembly of the present invention can serve not only as a protective component for preventing foreign matter from adhering to the exposure plate within an EUV exposure apparatus, but also as a protective component for protecting the exposure plate during storage or handling. Methods for attaching the protective film assembly to an exposure plate such as a photomask and manufacturing an exposure plate with the protective film assembly include methods such as attachment using the photomask adhesive, electrostatic adsorption, and mechanical fixation.

[0090] The method for manufacturing a semiconductor device or liquid crystal display panel according to this embodiment includes the step of exposing a substrate (semiconductor wafer or liquid crystal substrate) using an exposure master with a protective film assembly. For example, in the photolithography step, which is one of the manufacturing steps of a semiconductor device or liquid crystal display panel, the exposure master with the protective film assembly is placed on a stepper for exposure in order to form a photoresist pattern corresponding to integrated circuits, etc., on the substrate. Typically, in EUV exposure, EUV light is reflected by the exposure master and guided to the substrate using a projection optics system, which is performed under reduced pressure or vacuum. Therefore, even if foreign matter adheres to the protective film assembly during the photolithography step, this foreign matter will not be imaged on the wafer coated with photoresist, thus preventing short circuits or open circuits in integrated circuits, etc., caused by the image of foreign matter. Therefore, by using an exposure master with a protective film assembly, the yield in the photolithography step can be improved.

[0091] Example

[0092] The following examples and comparative examples illustrate the present invention, but the present invention is not limited to the following examples.

[0093] [Example 1]

[0094] A titanium protective film frame (150mm × 118mm × 1.5mm, frame width 4.0mm) was fabricated. The surfaces of the titanium frame (upper, lower, inner, and outer surfaces) were cleaned with sandpaper (1000 grit) to remove surface machining scratches, and then manually polished using metal polishing powder (PIKAL liquid manufactured by Nippon Abrasive Industries, Ltd.). The protective film frame was cleaned using ultrasonic cleaning with pure water and a neutral detergent. On the upper surface of the frame, a material was applied with a width of 1mm and a thickness of 0.1mm, consisting of 100 parts by weight of silicone adhesive (X-40-3264 manufactured by Shin-Etsu Chemical Industries, Ltd.) mixed with 1 part by weight of a hardener (PT-56 manufactured by Shin-Etsu Chemical Industries, Ltd.) as the protective film adhesive. Additionally, on the lower end face of the frame, covering the entire circumference, a material is applied with a width of 1 mm and a thickness of 0.1 mm. This material is prepared by mixing 100 parts by weight of acrylic adhesive (SK-Dyne 1495 manufactured by Sogen Chemical Co., Ltd.) with 0.1 parts by weight of hardener (L-45 manufactured by Sogen Chemical Co., Ltd.) and stirring. The protective film frame is then heated at 90°C for 12 hours to harden the protective film adhesive and mask adhesive on both the upper and lower end faces. Subsequently, an extremely thin silicone film serving as the protective film is pressed onto the protective film adhesive formed on the upper end face of the frame, thereby completing the protective film assembly.

[0095] [Example 2]

[0096] After fabricating the titanium frame, a sandblasting process using a sandblasting device is performed to remove surface scratches instead of sandpaper, and a chemical polishing process is performed instead of polishing with metal polishing powder. Otherwise, the protective film assembly is completed in the same manner as in Example 1. The sandblasting and chemical polishing conditions used here are as follows.

[0097] <Sandblasting conditions>

[0098] • Abrasive: Glass beads manufactured by Fuji Seisakusho (center diameter ≤ 30μm)

[0099] • Ejection pressure: 7 kgf / cm 2

[0100] • Time: 30 seconds

[0101] <Chemical grinding conditions>

[0102] • Liquid: "S-CLEAN S-22" manufactured by Sasaki Chemicals (Co., Ltd.)

[0103] Temperature: 30℃

[0104] Processing time: 10 seconds

[0105] [Example 3]

[0106] Following chemical polishing, the material is colored purple by anodizing. Otherwise, the protective film assembly is completed in the same manner as in Example 2.

[0107] [Example 4]

[0108] An aluminum alloy protective film frame was made instead of a titanium protective film frame. The surface was treated with a sandblasting process under the same conditions as in Example 2 to remove surface scratches using sandpaper. Anodizing, black dyeing, and sealing were performed to form a black oxide film on the surface instead of grinding with metal polishing powder. Otherwise, the protective film assembly was completed in the same manner as in Example 1.

[0109] [Comparative Example 1]

[0110] The protective film assembly was completed under the same conditions as in Example 2, with the removal of surface scratches by sandpaper instead of sanding, and the surface was colored purple by anodizing instead of polishing with metal polishing powder.

[0111] [Comparative Example 2]

[0112] The protective film assembly was completed in the same manner as in Example 1, except that a chemical polishing process was performed under the same conditions as in Example 2 instead of polishing with metal polishing powder.

[0113] Visual inspection and surface roughness measurement were performed on the protective film assemblies obtained in Examples 1 to 4, and Comparative Examples 1 and 2. In addition, the reflectance of each sample was measured using a sample piece made of the same material as that used in Examples 1 to 4, and Comparative Examples 1 and 2, and the material was subjected to surface treatment.

[0114] [Reflectance Measurement]

[0115] Prepare a 3cm×3cm sample with a thickness of 5mm and perform the same surface treatment as in Examples 1 to 4, as well as Comparative Examples 1 and 2. The reflectance at 550nm was measured using a "Spectrophotometer V-780" (manufactured by Nippon Spectrophotometer Co., Ltd., model name).

[0116] [Surface Roughness Measurement]

[0117] Using a 3D measurement laser microscope "LEXT OLS4000" (manufactured by Olympus Corporation, model name), measurements were taken at four points on the central part of the inner side of each side of the frame of the protective film assembly in each example under the following conditions. Figure 1 The arithmetic mean roughness Ra, root mean square height Rq, and kurtosis (Rku) at the symbols P, P, P, P) are given.

[0118] <LEXT OLS4000 Measurement Conditions>

[0119] • Evaluation length: 4mm

[0120] • Cutoff values: λc 800μm, λs 2.5μm, no λf

[0121] • Filter: Gaussian filter

[0122] • Analysis parameters: Roughness parameters

[0123] • Objective lens: ×50

[0124] [Visual Inspection]

[0125] A 20μm standard particle was attached to a portion of the inner wall surface of the obtained protective film assembly. The inspectability of the foreign object was evaluated in a dark room while a spotlight was shone on it, according to the following criteria.

[0126] <Judgment Criteria>

[0127] ○: No scattered light was detected in the parts where no particles were attached, but scattered light was detected in the parts where only particles were attached.

[0128] ×: Scattered light was also detected in areas where no particles were attached.

[0129] [Table 1]

[0130]

[0131] Based on the results in Table 1, the following aspects are examined.

[0132] In the protective film frames of Comparative Examples 1 and 2, although the reflectivity was low or the arithmetic mean roughness Ra was small, the kurtosis (Rku) exceeded 3. As a result, it was found that the visual inspection of foreign objects was poor.

[0133] On the other hand, regarding the protective film frames of Examples 1 to 4, whose kurtosis (Rku) of the frame surface is 3 or less, it was found that the foreign object inspection was good based on visual inspection, regardless of the magnitude of the values ​​of other height parameters of the reflectivity or roughness curve, namely Ra or Rq.

Claims

1. A protective film frame, comprising a frame-shaped protective film frame having an upper end surface on which a protective film is disposed and a lower end surface facing a photomask, characterized in that: The inner surface of the protective film frame has a roughness curve with a kurtosis of 3.0 or less, and a reflectivity of 5% or more and 20% or less for inspection light. The protective film frame is made of titanium or a titanium alloy, and An oxide film is formed on the surface of the protective film frame.

2. The protective film frame according to claim 1, wherein: The area with a roughness curve kurtosis of 3.0 or less is the entire inner surface area of ​​the protective film frame or the entire surface area of ​​the protective film frame.

3. The protective film frame according to claim 1, wherein: The protective film frame is a frame-shaped structure with edges, and the kurtosis of the roughness curve is the measured value of the central part of the inner surface of the edge.

4. The protective film frame according to claim 1, wherein: The kurtosis of the roughness curve is below 2.

9.

5. The protective film frame according to claim 1, wherein: The kurtosis of the roughness curve is below 2.

8.

6. The protective film frame according to claim 1, wherein: The kurtosis of the roughness curve is below 2.

7.

7. The protective film frame according to claim 1, wherein: The kurtosis of the roughness curve is greater than or equal to 0.

1.

8. The protective film frame according to claim 1, wherein: The kurtosis of the roughness curve is greater than or equal to 0.

5.

9. The protective film frame according to claim 1, wherein: The average roughness of at least a portion of the inner surface of the protective film frame is in the range of 0.001 to 1.

0.

10. The protective film frame according to claim 9, wherein: The protective film frame is a frame-shaped structure with edges, and the average roughness is the measured value of the central part of the inner surface of the edge.

11. The protective film frame according to claim 1, wherein: At least a portion of the inner surface of the protective film frame has a root mean square height ranging from 0.001 to 1.

0.

12. The protective film frame according to claim 11, wherein: The protective film frame is a frame-shaped structure with sides, and the root mean square height is the measured value of the center of the inner side of the side.

13. The protective film frame according to claim 1, wherein: The wavelength of the light being examined is 550 nm.

14. The protective film frame according to claim 1, wherein: The reflectance was measured using a V-780 spectrophotometer manufactured by Japan Spectrophotometer Co., Ltd.

15. The protective film frame according to claim 1, wherein: The thickness of the protective film frame is less than 2.5 mm.

16. The protective film frame according to claim 1, wherein: The thickness of the protective film frame is less than 1.5 mm.

17. The protective film frame according to claim 1, wherein: The thickness of the protective film frame is 1.0 mm or more.

18. The protective film frame according to claim 1, wherein: The surface of the protective film frame was blackened.

19. The protective film frame according to claim 1, wherein: The surface of the protective film frame is subjected to physical or chemical abrasion.

20. The protective film frame according to claim 1, wherein it is a protective film frame for a protective film assembly for extreme ultraviolet light.

21. A protective film assembly, comprising: The protective film frame and the protective film as described in any one of claims 1 to 20.

22. A protective film assembly, comprising: The protective film frame as described in any one of claims 1 to 20, and the protective film disposed on one end face of the protective film frame via an adhesive or bonding agent.

23. The protective film assembly according to claim 21 or 22, wherein: The protective film is placed on the upper surface of the protective film frame.

24. The protective film assembly according to claim 21 or 22, wherein: The protective film is a silicon film or a carbon film.

25. The protective film assembly according to claim 24, wherein: The carbon film is made of graphene, cobalt-like carbon, or carbon nanotubes.

26. The protective film assembly according to claim 21 or 22, wherein: The protective film includes a support frame that supports the protective film.

27. The protective film assembly according to claim 21 or 22, wherein: The height of the protective film assembly is less than 2.5 mm.

28. The protective film assembly according to claim 21 or 22, used in exposure under vacuum or reduced pressure.

29. The protective film assembly according to claim 21 or 22, which is used for extreme ultraviolet light exposure.

30. An exposure master with a protective film assembly, characterized in that: The original exposed version is equipped with a protective film assembly as described in any one of claims 21 to 29.

31. The exposure master with a protective film assembly according to claim 30, wherein: The original exposure version is the original exposure version used for extreme ultraviolet light.

32. The exposure master of the protective film assembly according to claim 30, wherein it is an exposure master of the protective film assembly for extreme ultraviolet lithography.

33. An exposure method, characterized in that: Exposure is performed using an exposure original with a protective film assembly as described in any one of claims 30 to 32.

34. The exposure method according to claim 33, wherein: The light source used for exposure is an exposure source that emits extreme ultraviolet light.

35. A method for manufacturing a semiconductor device, characterized in that... include: The process of exposing a substrate under vacuum or reduced pressure using an exposure master with a protective film assembly as described in any one of claims 30 to 32.

36. The method of manufacturing a semiconductor device according to claim 35, wherein: The light source used for exposure is an exposure source that emits extreme ultraviolet light.

37. A method for manufacturing a liquid crystal display panel, characterized in that... include: The process of exposing a substrate under vacuum or reduced pressure using an exposure master with a protective film assembly as described in any one of claims 30 to 32.

38. The method for manufacturing a liquid crystal display panel according to claim 37, wherein: The light source used for exposure is an exposure source that emits extreme ultraviolet light.

39. An application of the protective film frame as described in any one of claims 1 to 20 in the manufacture of a protective film assembly for extreme ultraviolet light.

40. An application of a protective thin film assembly as described in any one of claims 21 to 29 to extreme ultraviolet lithography.

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