Pellicle case, pellicle housing body, and pellicle inspection method

Abstract

A pellicle case according to the present disclosure is used for housing, in an airtight state, a pellicle having a pellicle film. The pellicle case comprises a body and a lid. The body has a first planar window. The lid has a second planar window opposing the first planar window. The pellicle satisfies at least one of (a) and (b).　(a): A light-blocking layer is formed on at least a portion of the outer surface of one of the first planar window and the second planar window, the transmittance of the planar window on the side where the light-blocking layer is not formed is at least 75% with respect to light having a wavelength of 0.4-0.7 μm, and the reflectance of the light-blocking layer is at most 5% with respect to light having a wavelength of 0.4-0.6 μm. (b) The transmittances of the first planar window and the second planar window are at least 70% with respect to light having a wavelength of 2-10 μm.

Description

Pellicle case, pellicle container, and pellicle inspection method

[0001] The present disclosure relates to a pellicle case, a pellicle container, and a method for inspecting a pellicle.

[0002] The manufacturing process of semiconductor devices includes a lithography process in which a pattern is formed on a semiconductor wafer by irradiating light onto the wafer. In the lithography process, for example, a pattern formed on a rectangular photomask substrate is irradiated with light (also called "exposure light"), and the exposure light transmitted through or reflected by the photomask substrate is imaged on the wafer, exposing the resist material on the wafer. This transfers the predetermined pattern onto the wafer.

[0003] In lithography processes, pellicles are used to prevent foreign matter from adhering to a pattern formed on a photomask substrate. The pellicle is attached to the photomask substrate to surround the pattern formed on the photomask substrate. Typically, a pellicle comprises a pellicle frame and a pellicle film. The pellicle frame is positioned so as to surround the outside of the pattern area formed on the photomask substrate. The pellicle film is stretched over the pellicle frame.

[0004] In recent years, pellicles having carbon nanotube films (hereinafter also referred to as "CNT films") have been studied as pellicle films. CNT films tend to adsorb gases from the surrounding environment (e.g., the atmosphere). It has been found that when gases are adsorbed onto the CNT film, the properties of the CNT film (e.g., the transmittance of EUV light) change from the properties immediately after the CNT film is manufactured. If the properties of the CNT film change significantly from the properties immediately after the CNT film is manufactured, the CNT film may affect the pattern formed on the semiconductor wafer.

[0005] Patent Document 1 discloses a case for housing a pellicle (hereinafter also referred to as a "pellicle case"). The pellicle case has a tray and a lid that covers the tray. The pellicle case has a sealed structure. The sealed structure seals the gap between the periphery of the lid and the tray when the lid that covers the tray is bent under its own weight. Engineering plastic, reinforced plastic, and metal are disclosed as materials for the lid and the tray.

[0006] On the other hand, Non-Patent Document 1 discloses that by heating the CNT film to a temperature exceeding 2000° C., it is possible to reduce the change in transmittance of the CNT film over time.

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-79545

[0008] Non-patent document 1: Mark van de Kerkhofa, et al., “EUV pellicle scanner integration for N2 nodes and beyond”, Vol. 12494, Proc. of SPIE, 2023, 124940D-1 to 124940D-9

[0009] Pellicles are usually shipped housed in a pellicle case and are removed from the case before use. There are cases where it is desirable to check the condition of the CNT film immediately before using the pellicle.

[0010] For example, by measuring the ratio of the intensity of the G band to the intensity of the D band of the CNT film (hereinafter also referred to as the "G / D ratio") by Raman spectroscopy, it is possible to inspect whether or not defects have occurred in the CNTs that make up the CNT film. In the present disclosure, the "intensity of the D band" refers to the intensity of the D band (1360 cm) derived from a defect structure of the graphite structure (SP2 bond). －１ The "G band intensity" refers to the G band (around 1580 cm) derived from the graphite structure (SP2 bond). －１ The graph shows the peak intensity around the G / D ratio. The larger the G / D ratio, the higher the crystallinity of the CNTs that make up the CNT film. In other words, the larger the G / D ratio, the fewer defects there are in the CNTs that make up the CNT film.

[0011] By measuring the emissivity of a CNT film using Fourier transform infrared spectroscopy (hereinafter also referred to as "FTIR"), it is possible to inspect whether a gas is adhering to the CNT film. Generally, the reflectance ρ, transmittance τ, and absorptance α of energy incident on an object have a specific relationship (i.e., reflectance ρ + transmittance τ + absorptance α = 1). In this disclosure, the "emissivity" of a certain wavelength refers to the absorptance α obtained by subtracting the transmittance τ and reflectance ρ of a certain wavelength from the energy incident on an object in thermal equilibrium. To measure the emissivity, for example, a spectroradiometer ("JIR-E500" manufactured by JEOL Ltd.) is used. The emissivity of a CNT film without gas adhering differs from the emissivity of a CNT film with gas adhering. Therefore, by comparing the measured emissivity of a CNT film with the measured emissivity of a CNT film without gas adhering, it is possible to inspect whether a gas is adhering to the CNT film.

[0012] However, when using the pellicle case disclosed in Patent Document 1, it is necessary to remove the pellicle from the pellicle case to check the state of the CNT film. As described above, CNT films tend to adsorb gases from the surrounding environment. This may make it difficult to accurately inspect the state of the CNT film. Therefore, there is a need for a pellicle case that enables inspection of pellicle films housed in a vacuum-sealed state.

[0013] The present disclosure has been made in consideration of the above circumstances. A problem to be solved by one embodiment of the present disclosure is to provide a pellicle case and a pellicle container that enable inspection of a pellicle membrane that is housed in a sealed state. A problem to be solved by another embodiment of the present disclosure is to provide a pellicle inspection method that allows easy inspection of a pellicle membrane that is housed in a pellicle case in a sealed state under reduced pressure.

[0014] Means for solving the above problems include the following embodiments: <1> A pellicle case for hermetically storing a pellicle having a pellicle membrane, comprising: a main body and a lid, wherein the main body has a first plane window for inspecting the pellicle membrane, and the lid has a second plane window for inspecting the pellicle membrane that faces the first plane window, and the pellicle case satisfies at least one of the following (a) and (b): (a) A light-shielding layer is formed on at least a portion of an outer surface of one of the first and second planar windows, and the planar window of the first and second planar windows on which the light-shielding layer is not formed has a transmittance of 75% or more for light having a wavelength of 0.4 μm to 0.7 μm, and a reflectance of the light-shielding layer for light having a wavelength of 0.4 μm to 0.6 μm of 5% or less. (b) The transmittance of each of the first and second planar windows for light having a wavelength of 2 μm to 10 μm is 70% or more. <2> The pellicle case according to <1>, which satisfies (a), and in which a light-shielding layer is formed on the entire outer surface of one of the first and second planar windows. <3> The pellicle case according to <1>, which satisfies (b). <4> The pellicle case according to <1>, which satisfies (a), and in which a light-shielding layer is formed on a portion of an outer surface of one of the first and second planar windows. <5> The pellicle case according to <4>, further satisfying (b). <6> The pellicle case according to any one of <1> to <5>, wherein at least one of the main body and the lid has an air passage communicating the inside and outside of the pellicle case, a valve capable of opening and closing the air passage, and a filter arranged in the air passage, wherein the filter is located closer to the inside of the pellicle case than the valve. <7> A pellicle container comprising: the pellicle case according to any one of <1> to <6>, and a pellicle contained in the pellicle case in a sealed state, wherein the pellicle has a pellicle membrane, and the first plane window and the second plane window face each other via the pellicle membrane.<8> A method for inspecting the pellicle contained in the pellicle container described in <7> in a sealed state, wherein the pellicle case satisfies (a), the pellicle film contains a plurality of carbon nanotubes, and the method comprises measuring a ratio of a G band intensity to a D band intensity by Raman spectroscopy by irradiating the pellicle film with excitation light through the other of the first plane window and the second plane window. <9> A method for inspecting the pellicle contained in the pellicle container described in <7> in a sealed state under reduced pressure, wherein the pellicle case satisfies (b), and the method comprises measuring an emissivity by Fourier transform infrared spectroscopy by irradiating the pellicle film with continuous light through one of the first plane window and the second plane window.

[0015] According to one embodiment of the present disclosure, a pellicle case and a pellicle container can be provided that enable inspection of a pellicle membrane that is housed in a sealed state. Another embodiment of the present disclosure aims to solve a problem by providing a pellicle inspection method that can easily inspect a pellicle membrane that is housed in a sealed state in a pellicle case.

[0016] Fig. 1 is a perspective view of the appearance of a pellicle container according to a first embodiment of the present disclosure. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. Fig. 3 is a cross-sectional view of a pellicle container according to a second embodiment of the present disclosure. Fig. 4 is a cross-sectional view of a pellicle container according to a third embodiment of the present disclosure.

[0017] In this disclosure, numerical ranges indicated using "to" mean ranges that include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In numerical ranges described in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the Examples. In this disclosure, a combination of two or more preferred aspects is a more preferred aspect. In this disclosure, when multiple substances corresponding to each component are present, the amount of each component refers to the total amount of multiple substances unless otherwise specified. In this specification, the term "process" includes not only independent processes, but also processes that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. In this disclosure, "EUV light" refers to light with a wavelength of 1 nm or more and 30 nm or less. The wavelength of EUV light is preferably 5 nm or more and 13.5 nm or less.

[0018] Hereinafter, a pellicle case, a pellicle container, and a pellicle inspection method according to an embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0019] (1) Pellicle Case The pellicle case of the present disclosure is a pellicle case for sealingly housing a pellicle having a pellicle membrane. The pellicle case includes a main body and a lid. The main body has a first planar window for inspecting the pellicle membrane. The lid has a second planar window for inspecting the pellicle membrane. The second planar window faces the first planar window. The pellicle case of the present disclosure satisfies at least one of the following (a) and (b): (a) A light-shielding layer is formed on at least a portion of the outer surface of one of the first and second flat windows, and the flat window on which the light-shielding layer is not formed has a transmittance of 75% or more for light having a wavelength of 0.4 μm to 0.7 μm, and a reflectance of the light-shielding layer for light having a wavelength of 0.4 μm to 0.6 μm is 5% or less. (b) The transmittance of each of the first and second flat windows for light having a wavelength of 2 μm to 10 μm is 70% or more.

[0020] In this disclosure, a "planar window" refers to a window having the shape of a planar substrate. "Transmittance" can be calculated from the amount of light measured with and without a planar window for the wavelength of light to be measured. The amount of light can be measured in a dark box that prevents external light from entering. A spectrophotometer (e.g., "PHOTO RT" manufactured by Tokyo Instruments Inc.) or a Fourier transform infrared spectrophotometer (e.g., the Cary 600 series manufactured by Agilent Technologies Inc.) may be used to measure the amount of light. Typically, the transmittance of a resin window for light with wavelengths of 2 μm to 10 μm is less than 70%. The fact that the pellicle case of the present disclosure satisfies (b) indicates that the material of each of the first and second planar windows is not resin.

[0021] The pellicle case of the present disclosure, having the above-described configuration, enables inspection of a pellicle film housed in a sealed state. This effect is presumably due to, but not limited to, the following reasons. Measurement of the G / D ratio by Raman spectroscopy is typically performed by irradiating the pellicle film with excitation light having a wavelength of 532 nm and detecting the Raman scattered light generated through the plane window illuminated by the excitation light (i.e., as reflected light). The wavelength of the Raman scattered light is different from the wavelength of the excitation light. When the pellicle case satisfies (a), this indicates that the first and second plane windows are less likely to absorb the excitation light and the Raman scattered light, and the light-shielding layer is more likely to absorb the excitation light and the Raman scattered light. This makes it easier to accurately detect the Raman scattered light. In other words, the G / D ratio is more accurately measured. As a result, the pellicle case of the present disclosure enables inspection of the CNTs that make up the pellicle film (CNT film) housed in a sealed state for defects. Measurement of the emissivity of a pellicle film using the FTIR method is typically performed by irradiating the pellicle film with continuous light having a wavelength of 1 μm to 10 μm and detecting the generated emissivity using a spectrophotometric emissivity measurement device through the first and second plane windows. When the pellicle case satisfies (b), this indicates that the first and second plane windows are less likely to absorb continuous light. This makes it easier to accurately detect the emissivity. As a result, the pellicle case of the present disclosure makes it possible to inspect whether or not gas is adhering to the pellicle film housed in a sealed state.

[0022] The pellicle case has a space therein for accommodating the pellicle (hereinafter also referred to as the "accommodation space"), which is formed by a main body and a lid.

[0023] The shape and size of the pellicle case are not particularly limited and may be selected appropriately depending on the pellicle to be housed.

[0024] (1.1) Main Body The pellicle case of the present disclosure includes a main body. The pellicle to be housed is placed on the main body. The shape and size of the main body are not particularly limited and may be selected appropriately depending on the pellicle to be housed, etc.

[0025] (1.1.1) First Plane Window The main body has a first planar window for inspecting the pellicle membrane.

[0026] The shape of the first planar window is not particularly limited, and examples thereof include a circle, a polygon (for example, a triangle, a square, a pentagon, a hexagon, a heptagon, etc.), and an irregular shape.

[0027] The size of the first planar window is not particularly limited and is selected appropriately depending on the inspection method of the pellicle membrane, etc. When the shape of the first planar window is circular, the size of the first planar window may be 1 mmφ to 10 mmφ. The thickness of the first planar window is not particularly limited and is selected appropriately depending on the inspection method of the pellicle membrane, etc.

[0028] The number of first plane windows is not particularly limited and may be appropriately selected depending on the size of the first plane windows, etc. The number of first plane windows may be one, or two or more.

[0029] The position of the first planar window is not particularly limited. The position of the first planar window is preferably a position facing a portion of the periphery of the main surface of the pellicle film contained in the pellicle to be housed. The pellicle may have a pellicle frame and an adhesive layer at the end of the pellicle frame for attaching the pellicle to the photomask substrate. The periphery of the main surface of the pellicle film contained in the pellicle is more susceptible to contamination than the central portion of the main surface of the pellicle film due to the adhesive layer, etc. By arranging the first planar window in a position facing a portion of the periphery of the main surface of the pellicle film contained in the pellicle to be housed, the pellicle case of the present disclosure can improve the efficiency of inspection of the pellicle film housed in a sealed state.

[0030] The material of the first plane window will be described later.

[0031] (1.1.2) First Wall The main body may further include a first wall. The first wall preferably has a first through-hole, and the first plane window is fitted into and fixed to the first through-hole. This makes the pellicle case of the present disclosure less likely to generate gas than when the first plane window is fixed to the first through-hole with an adhesive. As a result, the pellicle case of the present disclosure enables more accurate inspection of the pellicle membrane.

[0032] The shape and size of the first wall are not particularly limited and may be appropriately selected depending on the pellicle to be housed. The material of the first wall is not particularly limited and may include metal, resin, etc.

[0033] (1.2) Lid The pellicle case of the present disclosure includes a lid. The lid is coupled to the main body to form a storage space for storing a pellicle. The shape and size of the lid are not particularly limited and may be selected appropriately depending on the pellicle to be stored.

[0034] (1.2.1) Second Plane Window The main body has a second plane window for inspecting the pellicle membrane.

[0035] The second plane window may be the same as the first plane window, except that it faces the first plane window. The second plane window may be the same as or different from the first plane window. The material of the second plane window will be described later.

[0036] (1.2.2) Second Wall The cover may further include a second wall. The second wall preferably has a second through-hole, and the second plane window is preferably fitted into and fixed to the second through-hole. This makes the pellicle case of the present disclosure less likely to generate gas than when the second plane window is fixed to the second through-hole with an adhesive. As a result, the pellicle case of the present disclosure enables more accurate inspection of the pellicle membrane.

[0037] The shape and size of the second wall are not particularly limited and may be selected appropriately depending on the pellicle to be housed. The material of the second wall is not particularly limited and may include metal, resin, etc. The material of the second wall may be the same as or different from the material of the first wall.

[0038] (1.3)(a) When the pellicle case of the present disclosure satisfies (a), the transmittance of each of the first and second planar windows for light having a wavelength of 0.4 μm to 0.7 μm (hereinafter also referred to as the "first transmittance") is 75% or more, preferably 90% or more. With a first transmittance of 90% or more, the pellicle case of the present disclosure enables more accurate inspection of the pellicle membrane.

[0039] Examples of materials that achieve a first transmittance of 75% or greater include potassium bromide (KBr), sapphire, thallium bromochloride (e.g., "KRS-6" manufactured by Crystal Base Co., Ltd.), fluoride / alkali halide single crystals, zinc sulfide (ZnS), and fused quartz (e.g., "IR Grade" manufactured by Neotron Co., Ltd.). Examples of materials that achieve a first transmittance of 90% or greater include thallium bromochloride and fused lime. When the pellicle case of the present disclosure satisfies (a), the materials of the first and second plane windows are preferably KBr, sapphire, ZnS, or fused quartz. When the material of the first plane window is hygroscopic, a dip coating (Toa Rikagaku Kenkyusho Co., Ltd.) to prevent moisture absorption may be applied to the first plane window.

[0040] When the pellicle case of the present disclosure satisfies (a), a light-shielding layer is formed on at least a portion of the outer surface of one of the first and second planar windows. The method for fixing the light-shielding layer to one of the first and second planar windows is not particularly limited, and examples include welding, a method using a known adhesive, and mechanical fastening.

[0041] The reflectance of the light-shielding layer to light with a wavelength of 0.4 μm to 0.6 μm (hereinafter simply referred to as "reflectance") is 5% or less.

[0042] Examples of materials that have a reflectance of 5% or less include butyl rubber (with carbon black added), black anodized aluminum, chromate-treated film, black iron oxide, black stainless steel, black titanium, black lacquer, and carbon nanotube film. When the pellicle case of the present disclosure satisfies (a), the material of the light-shielding layer is preferably black anodized aluminum, black iron oxide, black stainless steel, or black titanium.

[0043] (1.4)(b) When the pellicle case of the present disclosure satisfies (b), it is preferable that the transmittance of each of the first and second planar windows for light with a wavelength of 2 μm to 10 μm (hereinafter also referred to as the "second transmittance") is 70% or more, and the transmittance of each of the first and second planar windows for light with a wavelength of 1 μm to 20 μm (hereinafter also referred to as the "third transmittance") is 70% or more. By having the third transmittance of 70% or more, the pellicle case of the present disclosure enables more accurate inspection of the pellicle membrane.

[0044] Examples of materials that achieve a second transmittance of 70% or more include potassium bromide (KBr), sapphire, thallium bromochloride (e.g., "KRS-6" manufactured by Crystal Base Co., Ltd.), fluoride / alkali halide single crystals, zinc sulfide (ZnS), and fused silica (e.g., "IR Grade" manufactured by Neotron Co., Ltd.). Examples of materials that achieve a third transmittance of 70% or more include KBr and KRS-6. When the pellicle case of the present disclosure satisfies (b), the first and second plane windows are preferably made of KBr, sapphire, KRS-6, or ZnS. When the second plane window is made of a hygroscopic material, a dip coating (Toa Rikagaku Kenkyusho Co., Ltd.) to prevent moisture absorption may be performed.

[0045] (1.5) Pressure Equalization Mechanism At least one of the main body and the lid preferably further includes a pressure equalization mechanism for equalizing the pressure inside the sealed pellicle case (i.e., the storage space). The pressure equalization mechanism includes an air passage connecting the inside and outside of the pellicle case, a valve capable of opening and closing the air passage, and a filter disposed in the air passage. The filter is located closer to the inside of the pellicle case than the valve.

[0046] When removing a pellicle housed in a pellicle case in a sealed state, the pellicle membrane may be damaged by pressure caused by local air pressure differences within the storage space. By providing a pressure equalization mechanism in at least one of the main body and the lid, the pressure within the storage space of the pellicle case can be made uniform. This makes it less likely that pressure caused by local air pressure differences within the storage space will occur. As a result, the pellicle case of the present disclosure can suppress damage to the pellicle membrane when removing a pellicle housed in the pellicle case in a sealed state.

[0047] The ventilation passage connects the outside of the pellicle case with the accommodation space. The number of ventilation passages is not particularly limited, and may be one or more.

[0048] The valve can open and close the ventilation channel. The valve may be a known valve. The valve may be disposed at an entrance of the ventilation channel on the outside side of the pellicle case, or may be disposed within the ventilation channel.

[0049] The filter prevents foreign matter from entering the accommodation space from the outside of the pellicle case when the valve is in an open state. The filter may be any known filter that allows gas to pass through but blocks foreign matter (for example, dust).

[0050] (1.6) Airtight Seal The pellicle case of the present disclosure may further include an airtight seal. This improves the airtightness of the pellicle case of the present disclosure. Examples of the airtight seal include a gasket (e.g., an O-ring) interposed between the body and the lid, and a metal coating covering the contact area between the body and the lid.

[0051] (1.7) Fastener The pellicle case of the present disclosure may further include a fastener. The fastener fastens the main body and the lid so that the pellicle can be stored in the pellicle case in a sealed state. The fastener may be any known fastener.

[0052] (1.8) Support The pellicle case of the present disclosure may further include a support. The support is attached to at least one of the main body and the lid. The support supports and fixes the pellicle within the pellicle case. This allows the pellicle case of the present disclosure to prevent the housed pellicle from moving within the pellicle case and suppress foreign matter from adhering to the pellicle membrane. The support may include a contact part that comes into contact with the pellicle and a displacement mechanism (e.g., a leaf spring) that allows the contact part to be displaced. Examples of materials for the contact part include thermoplastic elastomers (e.g., polyester elastomers, polybutylene terephthalate elastomers, etc.) and fluororesins, etc., from the viewpoint of cushioning the impact when placing the pellicle. The support may be a known support.

[0053] (1.9) Preferred Aspects (1.9.1) First Aspect The pellicle case of the present disclosure preferably has the configuration (a1). The configuration (a1) indicates that the pellicle case satisfies the above (a) and that a light-shielding layer is formed on the entire outer surface of one of the first and second planar windows. When the pellicle case of the present disclosure satisfies the configuration (a1), the pellicle case of the present disclosure makes it possible to inspect whether or not defects have occurred in the CNTs that make up the pellicle film (CNT film) housed in a sealed state.

[0054] (1.9.2) Second Aspect The pellicle case of the present disclosure preferably has configuration (a2). Configuration (a2) indicates that the pellicle case satisfies (a) above and that a light-shielding layer is formed on a portion of the outer surface of one of the first and second planar windows. When the pellicle case of the present disclosure satisfies configuration (a2), the pellicle case of the present disclosure enables inspection of the hermetically-contained pellicle film using Raman spectroscopy and FTIR. In other words, the pellicle case of the present disclosure enables inspection of the CNTs constituting the hermetically-contained pellicle film (CNT film) for defects, and also enables inspection of the hermetically-contained pellicle film for adhesion of gas. Specifically, by irradiating the pellicle film (CNT film) with excitation light so that the excitation light and Raman scattered light hit the light-shielding layer, the pellicle case of the present disclosure enables inspection of the CNTs constituting the hermetically-contained pellicle film (CNT film) for defects. On the other hand, by irradiating the pellicle membrane with continuous light so that the continuous light does not hit the light-shielding layer, the pellicle case disclosed herein makes it possible to inspect whether gas is attached to the pellicle membrane contained in a sealed state.

[0055] When the pellicle case satisfies the configuration (a2), the transmittance of each of the first and second planar windows for light having a wavelength of 0.5 μm to 20 μm (hereinafter also referred to as the "fourth transmittance") is 50% or more, preferably 60% or more. When the fourth transmittance is 70% or more, the pellicle case of the present disclosure enables inspection of the pellicle film by Raman spectroscopy and FTIR.

[0056] Examples of materials that set the fourth transmittance to 50% or more include KBr and KRS-6. Examples of materials that set the fourth transmittance to 70% or more include KBr. When the pellicle case of the present disclosure satisfies (a1), the materials of the first and second plane windows are preferably KBr, sapphire, ZnS, or fused silica.

[0057] (1.9.3) Third Aspect The pellicle case of the present disclosure preferably satisfies the configuration (a2) and the above-mentioned (b). By satisfying the configuration (a2) and the above-mentioned (b), the pellicle case of the present disclosure enables inspection of the pellicle membrane contained therein in a sealed state by Raman spectroscopy and FTIR.

[0058] (1.9.4) Fourth Aspect: The pellicle case of the present disclosure preferably satisfies (b) above, thereby enabling inspection of whether or not gas is adhering to the pellicle membrane housed in the hermetically sealed state.

[0059] (2) Pellicle Container The pellicle container of the present disclosure includes the pellicle case of the present disclosure and a pellicle hermetically sealed within the pellicle case. The pellicle has a pellicle membrane. The first plane window and the second plane window face each other via the pellicle membrane.

[0060] The pellicle container of the present disclosure has the above-described configuration, and therefore enables inspection of the pellicle membrane contained in a sealed state.

[0061] The pellicle housing of the present disclosure can be obtained by, for example, assembling it in a clean room under a nitrogen atmosphere. The pellicle may be housed in a pellicle case in a vacuum-sealed state.

[0062] (2.1) Pellicle A pellicle typically includes a pellicle film and a pellicle frame. The pellicle film is stretched over one end of the pellicle frame in the height direction.

[0063] When the pellicle case is provided with a support, the pellicle may be fixed by the support within the pellicle case and be coupled to the main body and the lid.

[0064] (2.1.1) Pellicle Film The pellicle includes a pellicle film. The pellicle film prevents foreign matter from adhering to the surface of the photomask substrate and allows exposure light to pass through during exposure. Foreign matter includes dust. Examples of exposure light include deep ultraviolet (DUV) light and EUV light. EUV refers to light with a wavelength of 5 nm to 30 nm.

[0065] The pellicle membrane covers the entire opening of the through-hole in the pellicle frame. The pellicle membrane may be supported on one end of the pellicle frame directly or via an adhesive layer. The adhesive layer may be a cured product of a known adhesive.

[0066] The thickness of the pellicle film is preferably 1 nm to 300 nm. The material of the pellicle film is not particularly limited, and examples thereof include cellulose-based resins, fluorine-based resins, carbon-based materials, SiN, polysilicon, and boron nitride, depending on the exposure light source used. Carbon-based materials include carbon nanotubes (hereinafter also referred to as "CNT"). Among these, the pellicle film preferably includes nanotubes, preferably CNTs or boron nitride, and more preferably CNTs. The nanotubes may be single-walled nanotubes, multi-walled nanotubes, or may include both single-walled and multi-walled nanotubes. The pellicle film may have a nonwoven structure. The nonwoven structure may be formed, for example, by fibrous nanotubes. The pellicle film may be a known pellicle film.

[0067] (2.1.2) Pellicle Frame The pellicle frame is a cylindrical object. The pellicle frame has a through-hole. The through-hole represents a space through which the exposed light that has passed through the pellicle film passes to reach the photomask substrate.

[0068] The shape of the pellicle frame corresponds to the shape of the photomask substrate. The shape of the pellicle frame as viewed from the height direction is not particularly limited, and examples thereof include a rectangular frame shape (e.g., a rectangular frame shape, a square frame shape, etc.).

[0069] The size of the pellicle frame may be any known size depending on the type of exposure light, etc.

[0070] The pellicle frame may or may not have ventilation holes. When the pellicle frame is attached to the photomask substrate, the ventilation holes connect the internal space of the pellicle with the external space of the pellicle. The "internal space of the pellicle" refers to the space surrounded by the pellicle and the photomask substrate. The "external space of the pellicle" refers to the space not surrounded by the pellicle and the photomask substrate.

[0071] Examples of materials for the pellicle frame include aluminum, titanium, stainless steel, ceramic materials (such as silicon and glass), and resins (such as polyethylene).

[0072] (3) Pellicle Inspection Method The pellicle inspection method of the present disclosure (hereinafter also referred to as the "first inspection method") is a method for inspecting the pellicle that is hermetically housed in the pellicle housing of the present disclosure. The pellicle case satisfies (a). The pellicle film includes a plurality of carbon nanotubes. The first inspection method includes irradiating the pellicle film with excitation light through the other of the first plane window and the second plane window by Raman spectroscopy, and measuring the intensity of the D band and the intensity of the G band (hereinafter also referred to as the "first measurement step").

[0073] The first inspection method, having the above-described configuration, can easily inspect a pellicle film hermetically housed in a pellicle case. Specifically, the first inspection method can measure the G / D ratio of a pellicle film hermetically housed in a pellicle case. That is, the first inspection method can inspect whether or not defects have occurred in the CNTs that make up a CNT film. For example, by using a pellicle determined to have no CNT defects and not using a pellicle determined to have CNT defects, it is possible to reliably irradiate light onto a semiconductor wafer in a desired pattern. A pellicle determined to have CNT defects can be cleaned by heating it to a temperature exceeding 2000°C (see Non-Patent Document 1). Using the cleaned pellicle can reliably irradiate light onto a semiconductor wafer in a desired pattern.

[0074] (3.1) First measurement step In the first measurement step, excitation light is irradiated onto the pellicle film through the other of the first plane window and the second plane window by Raman spectroscopy, and the ratio of the intensity of the G band to the intensity of the D band is measured.

[0075] The Raman spectroscopy measurement method may be a method using a known Raman spectrometer. Typically, the wavelength of the excitation light is 532 nm.

[0076] (4) Pellicle Inspection Method The pellicle inspection method of the present disclosure (hereinafter also referred to as the "second inspection method") is a method for inspecting the pellicle contained in a sealed state in the pellicle container of the present disclosure. The pellicle case satisfies (b) above. The second inspection method includes measuring the emissivity by Fourier transform infrared spectroscopy by irradiating the pellicle film with continuous light through one of the first plane window and the second plane window (hereinafter also referred to as the "second measurement step").

[0077] The second inspection method, having the above-described configuration, can easily inspect a pellicle film hermetically housed in a pellicle case. Specifically, the second inspection method can measure the emissivity of a pellicle film hermetically housed in a pellicle case. That is, the second inspection method can inspect whether or not a gas is adhering to the pellicle film. For example, by using a pellicle determined to have no gas adhering to its film and not using a pellicle determined to have gas adhering to its film, light can be reliably irradiated onto a semiconductor wafer in a desired pattern. A pellicle determined to have gas adhering to its film can be cleaned by heating it to a temperature exceeding 2000°C (see Non-Patent Document 1). Using the cleaned pellicle can reliably irradiate light onto a semiconductor wafer in a desired pattern.

[0078] (4.1) Second Measuring Step In the second measuring step, continuous light is irradiated onto the pellicle film through one of the first and second plane windows by an FTIR method to measure the emissivity.

[0079] The measurement method using the FTIR method may be a method using a known spectroscopic emissivity measuring device (for example, "JIR-E500" manufactured by JEOL Ltd.) The wavelength of the continuous light is usually 1 μm to 10 μm.

[0080] (5) First Embodiment (5.1) Pellicle Container As shown in Figures 1 and 2, a pellicle container 1A of the first embodiment includes a pellicle case 10A and a pellicle 20. The pellicle 20 is hermetically sealed and housed within the pellicle case 10A. The pellicle container 1A is a rectangular parallelepiped object.

[0081] Hereinafter, the longitudinal direction of the main surface of the pellicle housing 1A will be referred to as the X-axis direction, the lateral direction of the main surface of the pellicle housing 1A as the Y-axis direction, and the thickness direction of the pellicle housing 1A as the Z-axis direction. The X-axis, Y-axis, and Z-axis are each perpendicular to one another. Note that these directions do not limit the orientation of the pellicle housing of the present disclosure during use.

[0082] (5.1.1) Pellicle As shown in FIG. 2, the pellicle 20 has a pellicle film 21 and a pellicle frame 22. The pellicle film 21 is rectangular. The pellicle film 21 includes CNTs. The pellicle frame 22 is a rectangular frame. The longitudinal directions of the pellicle film 21 and the pellicle frame 22 are parallel to the X-axis direction. The lateral directions of the pellicle film 21 and the pellicle frame 22 are parallel to the Y-axis direction.

[0083] (5.1.2) Pellicle Case Pellicle case 10A is a pellicle case for hermetically housing pellicle 20 having pellicle membrane 21 (see FIG. 2). Pellicle case 10A includes main body 11A, lid 12A, pressure equalizing mechanism 13 (see FIG. 2), airtight seal 14 (see FIG. 2), and fastener 15.

[0084] (5.1.2.1) Main Body The main body 11A is bowl-shaped. The main body 11A has one first planar window 110A, a first wall 111, and a light-shielding layer 112A. The first planar window 110A faces a portion of the periphery of the main surface of the pellicle film 21. The first transmittance of the first planar window 110A is 75% or more. The first planar window 110A is circular. The diameter of the first planar window 110A may be 1 mmφ to 10 mmφ. The first wall 111 has a first through-hole H111 (see FIG. 2). The first planar window 110A is fitted into and fixed in the first through-hole H111. The light-shielding layer 112A is formed on the outer surface S110 of the first planar window 110A. The light-shielding layer 112A covers the entire outer surface S110 of the first flat window 110A. The reflectance of the light-shielding layer 112A is 5% or less.

[0085] (5.1.2.2) Lid The lid 12A is bowl-shaped. The lid 12A has one second planar window 120A and a second wall 121. The second planar window 120A faces the first planar window 110A in the Z-axis direction, with the pellicle film 21 interposed between them. The second planar window 120A has a first transmittance of 75% or more. The second planar window 120A has a circular shape. The diameter of the second planar window 120A may be 1 mmφ to 10 mmφ. The second wall 121 has a second through-hole H121 (see FIG. 2). The second planar window 120A is fitted into and fixed in the second through-hole H121.

[0086] (5.1.2.3) Pressure Equalization Mechanism The main body 11A is equipped with a pressure equalization mechanism 13. The pressure equalization mechanism 13 is used to equalize the pressure inside the sealed pellicle case 10A to atmospheric pressure. The pressure equalization mechanism 13 has an air vent R13, a valve 131, and a filter 132. The air vent R13 connects the inside and outside of the pellicle case 10A. The air vent R13 is formed in the first wall 111 of the main body 11A. The valve 131 is capable of opening and closing the air vent R13. The valve 131 is attached to the inlet of the air vent R13 on the outside side of the pellicle case 10A. The valve 131 is a known valve. The filter 132 is disposed in the air vent R13. The filter 132 is located closer to the inside of the pellicle case 10A than the valve 131. The filter 132 is a known filter (for example, a HEPA (High Efficiency Particulate Air Filter) and a ULPA (Ultra Low Penetration Air Filter)).

[0087] (5.1.2.4) Airtight Seal The airtight seal 14 is interposed between the main body 11 A and the lid 12 A. The airtight seal 14 is a known gasket (for example, an O-ring).

[0088] (5.1.2.5) Fastener Fastener 15 fastens main body 11A and lid 12A together, allowing pellicle 20 to be housed in pellicle case 10A in a sealed state. Any known fastener may be used as the fastener.

[0089] (5.2) First Inspection Method The first inspection method of the first embodiment includes a first measurement step. In the first measurement step, excitation light is irradiated onto the pellicle film 21 through the second plane window 120A by Raman spectroscopy, and the ratio of the G band intensity to the D band intensity is measured. Specifically, a Raman spectrometer is used to irradiate the pellicle film 21 with excitation light through the second plane window 120A, and Raman scattered light is detected through the second plane window 120A. From the Raman spectrum based on the detected Raman scattered light, the D band intensity and the G band intensity are read. The G / D ratio is obtained using the read D band intensity and G band intensity.

[0090] (5.3) Effects and Effects As described with reference to FIGS. 1 and 2, the pellicle case 10A includes a main body 11A and a lid 12A. The main body 11A has a first planar window 110A. The lid 12A has a second planar window 120A. The second planar window 120A faces the first planar window 110A. The pellicle case 10A satisfies the following (a): (a) A light-shielding layer 112A is formed on the entire outer surface S110 of the first planar window 110A, and the second planar window 120A has a transmittance of 75% or more for light with a wavelength of 0.4 μm to 0.7 μm, and the light-shielding layer 112A has a reflectance of 5% or less for light with a wavelength of 0.4 μm to 0.6 μm. This allows the pellicle case 10A to inspect the pellicle film 21 contained therein in a sealed state. Specifically, the G / D ratio can be measured more accurately by using pellicle case 10A, which allows inspection of the CNTs that make up pellicle film 21 housed in a sealed state to determine whether defects have occurred.

[0091] 1 and 2, a light-shielding layer 112A is formed on the entire outer surface S110 of the first planar window 110A, which allows the pellicle case 10A to be inspected for defects in the CNTs that make up the pellicle film 21 housed in a sealed state.

[0092] As described with reference to Figures 1 and 2, the main body 11A further includes a pressure equalization mechanism 13. This allows the pellicle case 10A to gradually increase the pressure inside the pellicle case 10A until it reaches atmospheric pressure. Therefore, even if the pellicle case 10A is opened in the atmosphere, pressure due to a pressure difference is unlikely to occur. As a result, the pellicle case 10A can suppress damage to the pellicle film 21 when the pellicle 20 housed in the pellicle case 10A in a sealed state is removed.

[0093] 1 and 2, the pellicle housing 1A includes a pellicle case 10A and a pellicle 20. The first planar window 110A and the second planar window 120A face each other via the pellicle film 21. This allows the pellicle housing 1A to inspect the pellicle film 21 housed in a sealed state.

[0094] 1 and 2, the first inspection method of the first embodiment includes a first measurement step, which allows the first inspection method of the first embodiment to easily inspect the pellicle membrane 21 housed in a sealed state in the pellicle case 10A.

[0095] (6) Second Embodiment (6.1) Pellicle Container The pellicle container 1B of the second embodiment has the same configuration as the pellicle container 1A of the first embodiment, except that the first and second planar windows are made of different materials and that no light-shielding layer is formed. As shown in FIG. 3, the pellicle container 1B of the second embodiment includes a pellicle case 10B and a pellicle 20.

[0096] (6.1.1) Pellicle Case The pellicle case 10B has the same configuration as the pellicle case 10A of the first embodiment, except that the first and second planar windows are made of different materials and that no light-shielding layer is formed. The pellicle case 10B includes a main body 11B, a lid 12B, a pressure equalizing mechanism 13, an airtight seal 14, and a fastener 15.

[0097] (6.1.1.1) Main Body The main body 11B has one first planar window 110B and a first wall 111. The first planar window 110B has the same configuration as the first planar window 110A, except that the second transmittance is 70% or more.

[0098] (6.1.1.2) Lid The lid 12B has one second planar window 120B and a second wall 121. The second planar window 120B has the same configuration as the second planar window 120A, except that the second transmittance is 70% or more.

[0099] (6.2) First Inspection Method The second inspection method of the second embodiment includes a second measurement step. In the second measurement step, continuous light is irradiated onto the pellicle film 21 through the second planar window 120B using the FTIR method to measure the emissivity. More specifically, a spectrophotometric emissivity measurement device is used to irradiate the pellicle film 21 with continuous light through the second planar window 120B, and simultaneously detect reflected light through the second planar window 120B and transmitted light through the first planar window 120A. The detected reflected light and transmitted light are used to obtain the emissivity.

[0100] (6.3) Effects and Benefits As described with reference to FIG. 3 , the pellicle case 10B includes a main body 11B and a lid 12B. The main body 11B has a first planar window 110B. The lid 12B has a second planar window 120B. The second planar window 120B faces the first planar window 110B. The pellicle case 10B satisfies the following condition (b): (b) The transmittance of each of the first planar window 120A and the second planar window 120B for light with wavelengths of 2 μm to 10 μm is 70% or more. This allows the pellicle case 10B to inspect the pellicle film 21 housed in a sealed state. Specifically, the use of the pellicle case 10B allows for more accurate measurement of emissivity. As a result, the pellicle case 10B allows for inspection of the CNTs that make up the pellicle film 21 housed in a sealed state.

[0101] 3, the second inspection method of the second embodiment includes a second measurement step, which makes it possible to easily inspect the pellicle membrane 21 that is housed in a sealed state in the pellicle case 10B.

[0102] (7) Third Embodiment (7.1) Pellicle Container A pellicle container 1C of the third embodiment has the same configuration as the pellicle container 1A of the first embodiment, except that a light-shielding layer is formed on a portion of the first plane window. As shown in FIG. 4, the pellicle container 1C of the third embodiment includes a pellicle case 10C and a pellicle 20.

[0103] (7.1.1) Pellicle Case The pellicle case 10C has the same configuration as the pellicle case 10A of the first embodiment, except that a light-shielding layer is formed on a portion of the first planar window. The pellicle case 10C includes a main body 11C, a lid 12A, a pressure equalizing mechanism 13, an airtight seal 14, and a fastener 15.

[0104] (7.1.1.1) Main Body The main body 11B has one first planar window 110A, a first wall 111, and a light-shielding layer 112C. The light-shielding layer 112C has the same configuration as the light-shielding layer 112A, except that it covers half of the outer surface S110 of the first planar window 110A in the positive direction of the X axis.

[0105] Hereinafter, the area of ​​the outer surface S110 of the first flat window 110A where the light-shielding layer 112C is formed will also be referred to as the "light-shielding area," and the area where the light-shielding layer 112C is not formed will also be referred to as the "non-light-shielding area."

[0106] (7.2) First Inspection Method The first inspection method of the third embodiment includes a first measurement step. In the first measurement step, excitation light is irradiated onto the pellicle film 21 through the second plane window 120A by Raman spectroscopy, and the ratio of the G band intensity to the D band intensity is measured. Specifically, using a Raman spectrometer, excitation light is irradiated onto the pellicle film 21 through the second plane window 120A, and Raman scattered light is detected through the second plane window 120A. At this time, the excitation light is irradiated so that the light that transmits through the pellicle film 21 efficiently hits the light-shielded region. From the Raman spectrum based on the detected Raman scattered light, the D band intensity and the G band intensity are read. The G / D ratio is obtained using the read D band intensity and G band intensity.

[0107] (7.3) Second Inspection Method The second inspection method of the third embodiment includes a second measurement step. In the second measurement step, continuous light is irradiated onto the pellicle film 21 through the second planar window 120B using the FTIR method to measure the emissivity. Specifically, using a spectrophotometric emissivity measurement device, continuous light is irradiated onto the pellicle film 21 through the second planar window 120B, and reflected light is detected through the second planar window 120B, while transmitted light is detected through the non-shielding region of the first planar window 120A. The emissivity is obtained using the detected reflected light and transmitted light.

[0108] (7.4) Effects and Effects As described with reference to FIG. 4 , the pellicle case 10C includes a main body 11C and a lid 12A. The main body 11C has a first planar window 110A. The lid 12A has a second planar window 120A. The second planar window 120A faces the first planar window 110A. The pellicle case 10C satisfies the following (a): (a) A light-shielding layer 112A is formed on a portion of the outer surface S110 of the first planar window 110A, and the transmittance of the second planar window 120A for light with a wavelength of 0.4 μm to 0.7 μm is 75% or more, and the reflectance of the light-shielding layer 112C for light with a wavelength of 0.4 μm to 0.6 μm is 5% or less. This allows the pellicle case 10C to inspect the pellicle film 21 contained therein in a sealed state using Raman spectroscopy and FTIR. Specifically, pellicle case 10C enables inspection of whether defects have occurred in the CNTs that make up pellicle film 21 that is housed in a sealed state, and also enables inspection of whether gas has adhered to pellicle film 21 that is housed in a sealed state. Specifically, by irradiating pellicle film 21 with excitation light so that excitation light and Raman scattered light strike light-shielding layer 112C (i.e., in the light-shielding region), pellicle case 10C enables inspection of whether defects have occurred in the CNTs that make up pellicle film 21 that is housed in a sealed state. On the other hand, by irradiating pellicle film 21 with continuous light so that continuous light does not strike light-shielding layer 112C (i.e., in the non-light-shielding region), pellicle case 10C enables inspection of whether gas has adhered to pellicle film 21 that is housed in a sealed state.

[0109] 4, the first inspection method of the third embodiment includes a first measurement step, which allows the first inspection method of the third embodiment to easily inspect the pellicle membrane 21 housed in a sealed state in the pellicle case 10C.

[0110] 4, the second inspection method of the third embodiment includes a second measurement step, which makes it possible to easily inspect the pellicle membrane 21 contained in the pellicle case 10C in a sealed state.

[0111] The disclosure of Japanese Patent Application No. 2023-218337, filed on December 25, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A pellicle case for accommodating a pellicle having a pellicle film in a sealed state, comprising a main body and a lid body, wherein the main body has a first flat window for inspecting the pellicle film, the lid body has a second flat window for inspecting the pellicle film facing the first flat window, and the pellicle case satisfies at least one of the following (a) and (b). (a) A light-shielding layer is formed on at least a part of the outer surface of one of the first flat window and the second flat window, and the transmittance of the flat window on the side where the light-shielding layer is not formed among the first flat window and the second flat window with respect to light having a wavelength of 0.4 μm to 0.7 μm is 75% or more, and the reflectance of the light-shielding layer with respect to light having a wavelength of 0.4 μm to 0.6 μm is 5% or less. (b) The transmittance of each of the first flat window and the second flat window with respect to light having a wavelength of 2 μm to 10 μm is 70% or more.

2. The pellicle case according to claim 1, which satisfies (a), and a light-shielding layer is formed on the entire outer surface of one of the first flat window and the second flat window.

3. The pellicle case according to claim 1, which satisfies (b).

4. The pellicle case according to claim 1, which satisfies (a), and a light-shielding layer is formed on a part of the outer surface of one of the first flat window and the second flat window.

5. The pellicle case according to claim 4, which further satisfies (b).

6. At least one of the main body and the lid body has a ventilation path that communicates the inside and the outside of the pellicle case, a valve that can open and close the ventilation path, and a filter disposed in the ventilation path, and the filter is located on the inner side of the pellicle case with respect to the valve. The pellicle case according to claim 1.

7. A pellicle container comprising the pellicle case according to any one of claims 1 to 6 and a pellicle accommodated in the pellicle case in a sealed state, wherein the pellicle has a pellicle film, and the first flat window and the second flat window face each other with the pellicle film therebetween.

8. A method for inspecting the pellicle accommodated in the pellicle container according to claim 7 in a sealed state, wherein the pellicle case satisfies the above (a), the pellicle film includes a plurality of carbon nanotubes, and the method includes irradiating the pellicle film with excitation light through the other of the first planar window and the second planar window by Raman spectroscopy and measuring the ratio of the intensity of the G band to the intensity of the D band. A method for inspecting a pellicle.

9. A method for inspecting the pellicle accommodated in the pellicle container according to claim 7 in a vacuum-sealed state, wherein the pellicle case satisfies the above (b), and the method includes irradiating the pellicle film with continuous light through one of the first planar window and the second planar window by Fourier transform infrared spectroscopy and measuring the emissivity. A method for inspecting a pellicle.

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