Reflective mask blank, method for producing reflective mask blank, reflective mask, method for producing reflective mask

Abstract

Provided is a reflective mask blank in which the ratio of the etching rate of an absorber film to the etching rate of a protective film is large.　A reflective mask blank according to the present invention comprises a substrate, a multi-layer reflective film that reflects EUV light, a protective film, and an absorber film in this order, wherein the absorber film contains platinum, the oxygen atom content in the absorber film is less than 20 at% with respect to all atoms of the absorber film, and the rhodium content in the outermost layer of the protective film on the absorber film side is not less than 50 at% with respect to all atoms of the outermost layer.

Description

Reflective mask blank, method for manufacturing a reflective mask blank, reflective mask, method for manufacturing a reflective mask

[0001] This invention relates to a reflective mask used in EUV (Extreme Ultra Violet) exposure, which is used in the exposure process of semiconductor manufacturing, a method for manufacturing the same, and a reflective mask blank, which is the original plate for the reflective mask.

[0002] In recent years, EUV lithography, which uses EUV light with a central wavelength of around 13.5 nm as a light source, has been investigated for further miniaturization of semiconductor devices.

[0003] In EUV lithography, reflective optics and reflective masks are used due to the characteristics of EUV light. In a reflective mask, a multilayer reflective film that reflects EUV light is formed on the substrate, and an absorbent film that absorbs EUV light is patterned on the multilayer reflective film.

[0004] EUV light incident on the reflective mask from the illumination optical system of the exposure apparatus is reflected in areas without the absorber film (apertures) and absorbed in areas with the absorber film (non-apertures). As a result, the mask pattern is transferred as a resist pattern onto the wafer through the reduction projection optical system of the exposure apparatus, and subsequent processing is carried out.

[0005] As for the material of the absorber film mentioned above, for example, Patent Document 1 discloses a material containing platinum (Pt). Patent Document 1 also discloses the provision of a protective film mainly composed of ruthenium (Ru) on the side of the multilayer reflective film opposite to the substrate side.

[0006] Japanese Patent Publication No. 2024-119143

[0007] When forming a reflective mask patterned with the absorber film described above, the absorber film is often subjected to dry etching. The inventors of this invention discovered that when processing an absorber film containing Pt by dry etching, depending on the material of the protective film, the protective film is also etched simultaneously with the absorber film. If the protective film is etched during the etching of the absorber film, it affects the reflectivity of the multilayer reflective film, preventing the transfer of the desired resist pattern. Therefore, it is necessary to suppress the etching of the protective film during the etching of the absorber film. In other words, the etching rate of the protective film must be lower than that of the absorber film.

[0008] The present invention has been made in view of the above problems, and aims to provide a reflective mask blank in which the ratio of the etching rate of the absorber film to the etching rate of the protective film is large. The present invention also aims to provide a method for manufacturing a reflective mask blank, a reflective mask, and a method for manufacturing a reflective mask.

[0009] As a result of diligent research into the above-mentioned problems, the present inventors discovered that by using a protective film in which the rhodium (Rh) content in the outermost layer on the absorber film side of the protective film is above a predetermined amount, the above-mentioned problems can be solved even when the absorber film contains Pt, thus leading to the completion of the present invention.

[0010] In other words, the inventors have found that the above problem can be solved by the following configurations: [1] A reflective mask blank having a substrate, a multilayer reflective film that reflects EUV light, a protective film, and an absorber film in this order, wherein the absorber film contains platinum, the oxygen atom content of the absorber film is less than 20 atomic percent of the total atoms of the absorber film, and the rhodium content of the outermost layer of the protective film on the absorber film side is 50 atomic percent or more of the total atoms of the outermost layer. [2] The reflective mask blank according to [1], wherein the ruthenium content of the outermost layer is less than 30 atomic percent of the total atoms of the outermost layer. [3] The reflective mask blank according to [1] or [2], wherein the outermost layer consists only of rhodium, or comprises rhodium and at least one element selected from the group consisting of ruthenium, niobium, molybdenum, tantalum, iridium, palladium, zirconium, aluminum, yttrium, and titanium. [4] The reflective mask blank according to any one of [1] to [3], wherein the absorber film consists only of platinum, or comprises platinum and at least one element selected from the group consisting of ruthenium, tantalum, tungsten, niobium, and molybdenum. [5] The reflective mask blank according to any one of [1] to [4], wherein the absorber film comprises platinum and at least one element selected from the group consisting of ruthenium, tantalum, tungsten, niobium, and molybdenum, and the platinum content in the absorber film is 80 atomic percent or less of the total atoms of the absorber film. [6] The reflective mask blank according to any one of [1] to [5], wherein the absorbent film comprises platinum and at least one element selected from the group consisting of tantalum and tungsten, and the platinum content in the absorbent film is 80 atomic percent or less with respect to the total atoms of the absorbent film. [7] The reflective mask blank according to any one of [1] to [6], wherein the absorbent film further comprises at least one element selected from the group consisting of boron, carbon, nitrogen and oxygen.[8] A reflective mask blank according to any one of [1] to [7], wherein the rhodium content in the protective film is 50 atomic percent or more in a layer with a film thickness of 0.5 to 5.0 nm. [9] A reflective mask having an absorber film pattern formed by patterning the absorber film of the reflective mask blank according to any one of [1] to [8].

[10] A method for manufacturing a reflective mask, comprising the step of forming an absorber film pattern by patterning the absorber film of the reflective mask blank according to any one of [1] to [8].

[11] A method for manufacturing a reflective mask blank having a substrate, a multilayer reflective film, a protective film, and an absorber film in this order, wherein the multilayer reflective film is formed on one main surface of the substrate, the protective film having an outermost layer with a rhodium content of 50 atomic percent or more is formed on the multilayer reflective film, and the absorber film containing platinum is formed on the protective film.

[0011] According to the present invention, a reflective mask blank can be provided in which the ratio of the etching rate of the absorber film to the etching rate of the protective film is large. Furthermore, according to the present invention, a method for manufacturing a reflective mask blank, a reflective mask, and a method for manufacturing a reflective mask can also be provided.

[0012] This is a cross-sectional view showing an example of an embodiment of the reflective mask blank of the present invention. This is a cross-sectional view showing an example of a manufacturing process for a reflective mask using the reflective mask blank of the present invention.

[0013] The present invention will now be described in detail. The following descriptions of constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.

[0014] The following is a definition of each term used in this specification. In this specification, numerical ranges expressed using "~" mean a range that includes the numbers before and after "~" as the lower and upper limits. In this specification, elements such as boron, carbon, nitrogen, oxygen, silicon, titanium, chromium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, tantalum, rhenium, iridium, and platinum may be represented by their corresponding element symbols (B, C, N, O, Si, Ti, Cr, Zr, Nb, Mo, Ru, Rh, Pd, Ta, Re, Ir, and Pt, etc.). Also, in this specification, silicon (Si) is included in the metallic elements.

[0015] <Reflective Mask Blank> The reflective mask blank of the present invention comprises, in this order, a substrate, a multilayer reflective film that reflects EUV light, a protective film, and an absorber film. Furthermore, the absorber film contains Pt, the O content of the absorber film is less than 20 atomic percent of the total atoms of the absorber film, and the Rh content of the outermost layer of the protective film on the absorber film side is 50 atomic percent or more of the total atoms of the outermost layer. The reflective mask blank of the present invention will be described with reference to the drawings.

[0016] Figure 1 is a cross-sectional view showing an example embodiment of the reflective mask blank of the present invention. The reflective mask blank 10 shown in Figure 1 has a substrate 12, a multilayer reflective film 14, a protective film 16, and an absorber film 18 in this order. The absorber film 18 contains Pt, and the O content is less than 20 atomic percent of the total atoms of the absorber film. In addition, the Rh content in the outermost layer of the protective film 16 on the absorber film 18 side is 50 atomic percent or more of the total atoms of the outermost layer. The reflective mask blank 10 may also have a hard mask film, described later, on the side of the absorber film 18 opposite to the substrate 12 side. Furthermore, the reflective mask blank 10 may also have a conductive film, described later, on the side of the substrate 12 opposite to the multilayer reflective film 14 side.

[0017] In the reflective mask blank of the present invention, the mechanism by which the ratio of the etching rate of the absorber film to the etching rate of the protective film becomes large is not entirely clear, but the inventors speculate as follows: When etching an absorber film containing Pt, dry etching is often performed using a gas containing a fluorine-based gas. When etching the absorber film using such a gas, the etching rate of the absorber film increases, and because the etching effect is large, the etching rate of the protective film also tends to increase. In the reflective mask blank of the present invention, the outermost layer on the absorber film side of the protective film contains a predetermined amount or more of Rh. Rh is difficult to etch during dry etching (for example, dry etching using the above-mentioned fluorine-based gas), and it is thought that the outermost layer containing a predetermined amount or more of Rh tends to have a low etching rate. Since the protective film is subjected to etching from the side on which the absorber film is placed, if a layer containing a predetermined amount or more of Rh is placed on the protective film side, it can be said that the etching rate of the protective film can be effectively reduced. In addition, if the O content is less than 20 atomic percent of the total atoms of the absorber film, the absorber film containing Pt becomes easier to etch. As a result, it is believed that in the reflective mask blank of the present invention, the ratio of the etching rate of the absorber film to the etching rate of the protective film becomes larger.

[0018] The configuration of the reflective mask blank of the present invention will be described below. Hereinafter, a large ratio of the etching rate of the absorber film to the etching rate of the protective film will also be referred to simply as a "large etching rate ratio."

[0019] [Substrate] The substrate of the reflective mask blank of the present invention preferably has a small coefficient of thermal expansion. A smaller coefficient of thermal expansion of the substrate helps to suppress distortion of the absorber film pattern due to heat during exposure with EUV light. The coefficient of thermal expansion of the substrate is 0 ± 1.0 × 10 at 20°C. －７ / ℃ is preferred, 0 ± 0.3 × 10 －７ / ℃ is more preferable. Examples of materials with a low coefficient of thermal expansion include SiO ２ -TiO ２Examples include glass and the like, but are not limited thereto. Crystallized glass in which a β - quartz solid solution is precipitated, quartz glass, metallic silicon, and substrates such as metals can also be used. SiO ２ -TiO ２ -based glass preferably uses quartz glass containing 90 to 95% by mass of SiO ２ and 5 to 10% by mass of TiO ２ . When the content of TiO ２ is 5 to 10% by mass, the linear expansion coefficient near room temperature is substantially zero, and almost no dimensional change occurs near room temperature. In addition, the SiO ２ -TiO ２ -based glass may contain trace components other than SiO ２ and TiO ２ .

[0020] The surface (hereinafter, also referred to as the "first main surface") on which the multilayer reflective film of the substrate is laminated preferably has high surface smoothness. The surface smoothness of the first main surface can be evaluated by surface roughness. The surface roughness of the first main surface is preferably 0.15 nm or less in terms of the root mean square roughness Rq. The surface roughness can be measured by an atomic force microscope, and the surface roughness is described as the root mean square roughness Rq based on JIS - B0601. The first main surface is preferably surface - processed to have a predetermined flatness in terms of enhancing the pattern transfer accuracy and position accuracy of the reflective mask obtained using the reflective mask blank. For the substrate, in a predetermined region (for example, a region of 132 mm × 132 mm) of the first main surface, the flatness is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less. The flatness can be measured by a flatness measuring instrument manufactured by Fujinon Corporation. The size, thickness, etc. of the substrate are appropriately determined according to the design values of the mask, etc. For example, the outer shape is 6 inches (152 mm) square, and the thickness is 0.25 inches (6.3 mm), etc. The substrate is often rectangular (rectangular) or square. Further, the substrate preferably has high rigidity in terms of preventing deformation due to the film stress of the film (multilayer reflective film, absorber film, etc.) formed on the substrate. For example, the Young's modulus of the substrate is preferably 65 GPa or more.

[0021] [Multilayer Reflective Film] The multilayer reflective film of the reflective mask blank of the present invention is not particularly limited as long as it has the desired properties as a reflective film for an EUV mask blank. The multilayer reflective film preferably has a high reflectivity to EUV light. Specifically, when EUV light is incident on the surface of the multilayer reflective film at an incident angle of 6°, the maximum reflectivity of EUV light around a wavelength of 13.5 nm is preferably 60% or more, and more preferably 65% ​​or more. Similarly, even when a protective film is laminated on the multilayer reflective film, the maximum reflectivity of EUV light around a wavelength of 13.5 nm is preferably 60% or more, and more preferably 65% ​​or more.

[0022] Since multilayer reflective films can achieve high reflectivity of EUV light, a multilayer reflective film is usually used in which a high refractive index layer exhibiting a high refractive index for EUV light and a low refractive index layer exhibiting a low refractive index for EUV light are alternately stacked multiple times. The multilayer reflective film may be stacked in multiple periods, with one period consisting of a stacked structure in which the high refractive index layer and the low refractive index layer are stacked in this order from the substrate side, or it may be stacked in multiple periods, with one period consisting of a stacked structure in which the low refractive index layer and the high refractive index layer are stacked in this order. A layer containing Si can be used as the high refractive index layer. As a material containing Si, in addition to pure Si, a Si compound containing Si and one or more elements selected from the group consisting of B, C, N, and O can be used. By using a high refractive index layer containing Si, a reflective mask with excellent reflectivity of EUV light can be obtained. As a low refractive index layer, a layer containing a metal selected from the group consisting of Mo, Ru, Rh, and Pt, or an alloy thereof, can be used. Si is widely used for the high refractive index layer, and Mo is widely used for the low refractive index layer. In other words, Mo / Si multilayer reflective coatings are the most common. However, multilayer reflective coatings are not limited to this, and Ru / Si multilayer reflective coatings, Mo / Be multilayer reflective coatings, Mo compound / Si compound multilayer reflective coatings, Si / Mo / Ru multilayer reflective coatings, Si / Mo / Ru / Mo multilayer reflective coatings, Si / Ru / Mo multilayer reflective coatings, and Si / Ru / Mo / Ru multilayer reflective coatings can also be used.

[0023] The film thickness of each layer constituting the multilayer reflective film and the number of repeating units of the layer can be appropriately selected according to the film material used and the required EUV light reflectance of the reflective layer. Taking a Mo / Si multilayer reflective film as an example, to obtain a multilayer reflective film with a maximum EUV light reflectance of 60% or more, a Mo film with a film thickness of 2.3 ± 0.1 nm and a Si film with a film thickness of 4.5 ± 0.1 nm should be stacked so that the number of repeating units is between 30 and 60. It is preferable that the multilayer reflective film has a reflectance of 60% or more for EUV light with an incident angle θ of 6°. It is more preferable that the above reflectance is 65% or more.

[0024] Each layer constituting the multilayer reflective film can be deposited to a desired thickness using known deposition methods such as DC sputtering, magnetron sputtering, and ion beam sputtering. For example, when fabricating a multilayer reflective film using ion beam sputtering, ion particles are supplied from an ion source to a target made of a high refractive index material and a target made of a low refractive index material. When the multilayer reflective film is a Mo / Si multilayer reflective film, for example, using ion beam sputtering, first a Si layer of a predetermined thickness is deposited on the substrate using a Si target. Then, a Mo layer of a predetermined thickness is deposited using a Mo target. These Si and Mo layers are stacked for, for example, 30 to 60 periods (preferably 40 to 50 periods) to form a Mo / Si multilayer reflective film.

[0025] [Protective Film] The reflective mask blank of the present invention has a protective film between the multilayer reflective film and the absorber film. The protective film is provided to protect the multilayer reflective film from damage during the etching process (usually a dry etching process) when a pattern is formed on the absorber film by etching. It is also preferable that the protective film protects the multilayer reflective film when the hard mask film described later is removed.

[0026] As described above, in the reflective mask blank of the present invention, the content of Rh in the outermost layer on the absorber film side of the protective film is 50 atomic% or more with respect to all atoms in the outermost layer. The content of Rh in the outermost layer is preferably 60 atomic% or more, more preferably 70 atomic% or more, with respect to all atoms in the outermost layer. Also, the content of Rh in the outermost layer may be 100 atomic% or less. That is, the outermost layer may consist only of Rh.

[0027] The outermost layer may consist only of Rh, or may contain elements other than Rh. For example, the outermost layer may contain Rh and at least one element selected from the group consisting of Ru, Nb, Mo, Ta, Ir, Pd, Zr, Al, Y, and Ti (hereinafter also referred to as "element X1"). When the outermost layer contains Ru as the element X1, the content of Ru in the outermost layer is preferably less than 50 atomic%, more preferably 40 atomic% or less, still more preferably less than 30 atomic%, with respect to all atoms in the outermost layer. The content of Ru in the outermost layer may be 0 atomic% or more. That is, it is also preferable that the outermost layer does not contain Ru.

[0028] Hereinafter, a method for measuring the elements contained in the outermost layer and their ratios will be described. In this specification, the measurement of the elements contained in the outermost layer and their ratios is performed by X-ray photoelectron spectroscopy (XPS: X-ray Photoelectron Spectroscopy). In this specification, the outermost layer on the absorber film side of the protective film refers to a region with a depth of 0.5 nm from the interface between the protective film and the absorber film to the side opposite to the absorber film side. Hereinafter, the details of the measurement method will be described.

[0029] For XPS analysis, the "PHI 5000 VersaProbe" analyzer manufactured by ULVAC-PHI, Inc. is used. The above instrument is calibrated in accordance with JIS K 0145. First, a measurement sample of approximately 1 cm square is cut out from a reflective mask blank. The obtained measurement sample is set in a measurement holder so that the absorber membrane side becomes the measurement surface. After the measurement holder is brought into the above instrument, the layer located on the opposite side of the absorber membrane from the substrate side is removed with an Ar ion beam to expose the absorber membrane. X-rays (monochromatic AlKα rays) are irradiated onto the exposed portion of the absorber membrane, and the analysis is performed with a photoelectron extraction angle (angle between the surface of the measurement sample and the direction of the detector) of 45°. In addition, a neutralization gun is used to suppress charge-up during the analysis. Here, when analyzing the thickness direction of the absorber film and protective film, the operation of removing a predetermined thickness from the outermost surface by sputtering with an Ar ion beam and the analysis operation described above are performed alternately and repeatedly. By performing the removal operation and the analysis operation alternately and repeatedly, spectra at each analysis depth can be obtained. The sputtering rate with the Ar ion beam can be measured using a sample prepared separately. The amount of outermost surface removed by the Ar ion beam is adjusted to 0.1 nm. The analysis is performed by wide scanning in the binding energy range of 1000 to 0 eV. The wide scan is performed with a pass energy of 58.7 eV, an energy step of 1 eV, a time / step of 50 ms, and two integrations. By analyzing the spectra obtained by wide scanning at each analysis depth using relative sensitivity coefficients specific to each element and each orbital, the content of each element at each analysis depth can be obtained. Once the content of each element at each analysis depth is obtained, the elemental distribution (depth profile) in the thickness direction of the measurement sample can be obtained.

[0030] In the depth profile, first, the elements contained in the absorber film are detected. When the analysis depth reaches near the interface between the absorber film and the protective film, the elements contained in the protective film are detected, and the detected amount of the elements contained in the absorber film decreases. In this specification, the interface between the protective film and the absorber film is defined as the depth position at which the profiles of the element most contained in the absorber film and the element most contained in the protective film intersect in the depth profile. From the above interface, in the region at a depth of 0.5 nm on the side opposite to the absorber film side, the content of Rh at each analysis depth is calculated, and an arithmetic mean value is obtained. The obtained arithmetic mean value is taken as the content of Rh in the outermost layer. Similarly, the content of elements other than Rh in the outermost layer can also be calculated. Note that analysis may be performed in the same procedure as above using a model sample formed under the same conditions as those for forming the protective film.

[0031] Also, in the protective film, the film thickness of the layer having a Rh content of 50 atomic% or more is preferably 0.5 nm or more, more preferably 1.0 nm or more, and even more preferably 1.5 nm or more. Also, in the protective film, the film thickness of the layer having a Rh content of 50 atomic% or more is preferably 10.0 nm or less, more preferably 6.0 nm or less, even more preferably 5.0 nm or less, particularly preferably 3.5 nm or less, and most preferably 2.5 nm or less.

[0032] The protective film may have a single-layer structure or a multilayer structure. When the protective film has a single-layer structure, it preferably contains 50 atomic% or more of Rh. Also, when the protective film has a multilayer structure, the layer of the protective film closest to the absorber film side has, as described above, a Rh content in the outermost layer of 50 atomic% or more based on all the atoms in the outermost layer.

[0033] The protective film may contain elements other than Rh. Examples of the elements other than Rh contained in the protective film include the above-described element X1. When the protective film contains elements other than Rh, it preferably contains Ru. Also, the protective film may contain at least one element selected from the group consisting of B, C, N, and O.

[0034] Examples of protective film configurations that satisfy the above-mentioned requirements for the outermost layer will now be described. When the protective film has a single-layer structure, examples include a protective film consisting only of Rh, and a configuration containing 50 atomic percent or more of Rh and the above-mentioned element X1. When the protective film has a multilayer structure, examples include an upper layer consisting only of Rh, or a configuration consisting of an upper layer containing 50 atomic percent or more of Rh and the above-mentioned element X1, and a lower layer which may contain Rh. When the protective film has a multilayer structure, the upper layer is positioned on the absorber film side. The lower layer may preferably contain Ru, or may consist only of Ru. When the lower layer consists only of Ru, the Rh from the upper layer is less likely to diffuse into the layer furthest from the substrate side of the multilayer reflective film (the Si layer if the multilayer reflective film is Mo / Si). Furthermore, in each of the above examples of configurations, at least one element selected from the group consisting of B, C, N, and O may be included.

[0035] The thickness of the protective film is preferably 10.0 nm or less, more preferably 6.0 nm or less, even more preferably 5.0 nm or less, and particularly preferably 3.5 nm or less, from the standpoint of maintaining the reflectance of EUV light reflected by the multilayer reflective film. Furthermore, the thickness of the protective film is preferably 1.0 nm or more, more preferably 1.5 nm or more, and even more preferably 2.0 nm or more, from the standpoint of obtaining good etching resistance. The thickness of the protective film is determined by X-ray reflectivity (XRR).

[0036] The protective film can be deposited using known deposition methods such as DC sputtering, magnetron sputtering, and ion beam sputtering. When depositing an Rh film by magnetron sputtering, it is preferable to use an Rh target as the target and Ar gas as the sputtering gas.

[0037] [Absorber Film] The absorber film of the reflective mask blank of the present invention is required to have high contrast between the EUV light reflected by the multilayer reflective film and the EUV light absorbed by the absorber film when the absorber film is patterned. The patterned absorber film (absorber film pattern) may function as a binary mask by absorbing EUV light, or it may function as a phase-shift mask that reflects EUV light and interferes with the EUV light from the multilayer reflective film to produce contrast. The absorber film pattern may be used as a binary mask as described later, or as a phase-shift mask as described later. In other words, the absorber film may be a phase-shift film. The absorber film contains Pt as described above, and the O content is less than 20 atomic percent of the total atoms of the absorber film.

[0038] The Pt content in the absorbent membrane is preferably 5 atomic% or more, more preferably 10 atomic% or more, even more preferably 20 atomic% or more, particularly preferably 30 atomic% or more, and may also be 40 atomic% or more, 50 atomic% or more, 60 atomic% or more, 70 atomic% or more, or 80 atomic% or more, relative to the total atoms contained in the absorbent membrane. Alternatively, the Pt content in the absorbent membrane may be 100 atomic% relative to the total atoms contained in the absorbent membrane. In other words, the absorbent membrane may consist only of Pt. If the absorbent membrane contains elements other than Pt, the Pt content in the absorbent membrane is preferably 95 atomic% or less, more preferably 90 atomic% or less, and more preferably 85 atomic% or less, relative to the total atoms contained in the absorbent membrane.

[0039] When the absorber film contains elements other than Pt, the other metal elements (other metal elements) are preferably one or more elements selected from the group consisting of Ru, Ta, W, Nb, and Mo. When the absorber film contains other metal elements, the total content of the other metal elements is preferably 90 atomic% or less, more preferably 80 atomic% or less, and even more preferably 70 atomic% or less, relative to the total atoms of the absorber film. When the absorber film contains other metal elements, the total content of the other metal elements is preferably 5 atomic% or more, and more preferably 10 atomic% or more, relative to the total atoms of the absorber film. The absorption film contains Pt and one or more elements selected from the group consisting of Ru, Ta, W, Nb, and Mo, which tends to improve the etching rate of the absorber film with fluorine-based gases.

[0040] In other words, it is preferable that the absorbent membrane consists only of Pt, or contains Pt and one or more elements selected from the group consisting of Ru, Ta, W, Nb, and Mo. It is also preferable that the absorbent membrane contains Pt and one or more elements selected from the group consisting of Ta and W. When the absorbent membrane contains Pt and one or more elements selected from the group consisting of Ta and W, the total content of one or more elements selected from the group consisting of Ta and W is preferably 5 atomic percent or more, more preferably 10 atomic percent or more, even more preferably 15 atomic percent or more, and particularly preferably 20 atomic percent or more. Furthermore, the total content of one or more elements selected from the group consisting of Ta and W is preferably 60 atomic percent or less, may be 50 atomic percent or less, or 45 atomic percent or less. When the absorbent membrane contains Pt and one or more elements selected from the group consisting of Ta and W, the Pt content in the absorbent membrane is preferably 95 atomic% or less, more preferably 90 atomic% or less, even more preferably 85 atomic% or less, and particularly preferably 80 atomic% or less, based on the total atoms of the absorbent membrane.

[0041] The absorber film may contain elements other than Pt and the other metallic elements mentioned above. Examples of elements other than Pt and other metallic elements include nonmetallic elements. Examples of nonmetallic elements include one or more elements selected from the group consisting of B, C, N, and O. That is, the absorber film may further contain one or more elements selected from the group consisting of B, C, N, and O. If the absorber film contains nonmetallic elements, the content is preferably less than 20 atomic percent, more preferably 15 atomic percent or less, and even more preferably 12 atomic percent or less, relative to the total atoms of the absorber film. If the absorber film contains nonmetallic elements, the content is preferably 0.5 atomic percent or more, and more preferably 1 atomic percent or more, relative to the total atoms of the absorber film. When the absorber film contains nonmetallic elements, the crystallinity of the absorber film tends to decrease. The content of oxygen atoms is preferably less than 20 atomic percent, and more preferably 15 atomic percent or less, and more preferably 12 atomic percent or less, relative to the total atoms of the absorber film, as this makes it easier to increase the etching rate of the absorber film. The oxygen atom content is preferably 0.5 atomic percent or more, and more preferably 1 atomic percent or more, relative to the total atoms of the absorber membrane.

[0042] The types and content of elements contained in the absorber film can be measured in accordance with the method for measuring the types and content of elements contained in the protective film (XPS method). Specifically, in the above procedure, after exposing the absorber film in the measurement sample, the absorber film is removed from the outermost surface to a thickness equal to half the thickness of the absorber film. The sputtering rate during the above removal can be measured in a separately prepared sample.

[0043] When an absorber film pattern is used as a binary mask, the absorber film must absorb EUV light and have a low reflectivity of EUV light. Specifically, when EUV light is irradiated onto the surface of the absorber film, the maximum reflectivity of EUV light around a wavelength of 13.5 nm should preferably be 2% or less. It is also preferable that the absorber film does not contain the metal elements found in the hard mask film described later. The crystalline state of the absorber film is preferably amorphous. This improves the smoothness and flatness of the absorber film. Furthermore, higher smoothness and flatness of the absorber film reduce the edge roughness of the absorber film pattern, thereby improving the dimensional accuracy of the absorber film pattern. When an absorber film pattern is used as a binary mask, the film thickness of the absorber film is preferably 40 to 70 nm, and more preferably 50 to 65 nm.

[0044] When using an absorber film pattern as a phase shift mask, the EUV light reflectance of the absorber film is preferably 2% or higher. To obtain a sufficient phase shift effect, the reflectance of the absorber film is preferably 9 to 15%. Using an absorber film as a phase shift mask improves the contrast of the optical image on the wafer and increases the exposure margin. It is also preferable that the absorber film does not contain the metal elements found in the hard mask film described later. When using an absorber film pattern as a phase shift mask, the film thickness of the absorber film is preferably 30 to 75 nm, and more preferably 35 to 55 nm. The film thickness of the absorber film is determined by the X-ray reflectance method.

[0045] The refractive index n of the absorber film at a wavelength of 13.5 nm is preferably 0.885 or higher, more preferably 0.890 or higher, and even more preferably 0.900 or higher. The refractive index n of the absorber film at a wavelength of 13.5 nm is preferably 0.935 or lower, more preferably 0.930 or lower, and even more preferably 0.925 or lower, in that it allows for a thinner film thickness of the phase-shift film when the absorber film is used as a phase-shift film. The extinction coefficient k of the absorber film at a wavelength of 13.5 nm is preferably 0.062 or lower, more preferably 0.060 or lower, and may also be 0.055 or lower, or 0.050 or lower. The extinction coefficient k of the absorber film at a wavelength of 13.5 nm is preferably 0.010 or higher, more preferably 0.015 or higher, and even more preferably 0.020 or higher, in that it allows for easier adjustment of the reflectance of the phase-shift film when the absorber film is used as a phase-shift film.

[0046] The refractive index n and extinction coefficient k can be obtained from the database of the Center for X-Ray Optics, Lawrence Berkeley National Laboratory, or from the "dependence on the angle of incidence" of reflectance described below. The angle of incidence θ of EUV light, the reflectance R for EUV light, the refractive index n of the film, and the extinction coefficient k of the film satisfy the following equation (1): R = |(sinθ - ((n+ik)² - cos2θ)¹ / ²) / (sinθ + ((n+ik)² - cos2θ)¹ / ²)| ... (1) The refractive index n and extinction coefficient k can be calculated by measuring multiple combinations of the angle of incidence θ and reflectance R, and fitting the multiple measurement data to minimize the error between equation (1).

[0047] In the reflective mask blank of the present invention, the crystallinity of the absorber film is preferably low. The crystalline state of the absorber film is preferably amorphous. This improves the smoothness and flatness of the absorber film. Furthermore, when the smoothness and flatness of the absorber film are high, the edge roughness of the absorber film pattern is reduced, and the dimensional accuracy of the absorber film pattern can be improved. Low crystallinity of the absorber film means that when a diffraction chart is obtained by X-ray diffraction (XRD), the total half-width of the peaks in the diffraction chart is large. CuKα rays are used as the X-ray source. XRD is performed using the Out-of-Plane method. When confirming the degree of crystallinity of the absorber film, the total half-width of the diffraction peak originating from the absorber film with the highest intensity in the range of 2θ from 20 to 50° is used. If no clear diffraction peak originating from the absorber film is observed in the above diffraction chart, the absorber film can be said to be amorphous. The full width at half maximum of the diffraction peak originating from the absorber film is preferably 1.0° or greater at 2θ. Whether or not a diffraction peak originates from the absorber film can be confirmed by identifying the elements contained in the absorber film using the method described above and comparing them with a diffraction pattern database. Alternatively, the crystallinity of the absorber film may be confirmed using a sample deposited under the same conditions as those used to deposit the absorber film.

[0048] The absorber film may be a single layer or a multilayer film consisting of multiple layers. If the absorber film is a single layer, the number of steps in mask blank manufacturing can be reduced, improving production efficiency. If the absorber film is a multilayer film, the layer located on the side opposite the protective film side of the absorber film may be an anti-reflective film used when inspecting the absorber film pattern using inspection light (for example, wavelength 193-248 nm). Examples of materials for forming the anti-reflective film include materials containing Ta and O.

[0049] Absorber films can be formed using known film deposition methods such as magnetron sputtering and ion beam sputtering. For example, when forming a RuPt film as an absorber film using magnetron sputtering, a Ru target and a Pt target are used, and sputtering is performed by supplying a gas containing Ar gas to form the absorber film. Alternatively, a RuPt alloy target may be used to form the RuPt film.

[0050] [Buffer Layer] The reflective mask blank of the present invention may have a buffer layer. Preferably, the buffer layer is provided between the protective film and the absorber film. Providing a buffer layer makes it easier to suppress the influence on the protective film and the multilayer reflective film during the etching process of the absorber film (usually a dry etching process).

[0051] The buffer layer preferably contains one or more elements selected from the group consisting of Ru, Cr, and Ta, and more preferably contains Ru. If the buffer layer contains Ru, the Ru content is preferably 80 atomic% or more, more preferably 90 atomic% or more, even more preferably 95 atomic% or more, and particularly preferably 97 atomic% or more, relative to the total atoms of the buffer layer. If the buffer layer contains Ru, the Ru content is preferably 99.7 atomic% or less, more preferably 99.5 atomic% or less, and even more preferably 99.2 atomic% or less, relative to the total atoms of the buffer layer. If the buffer layer contains Cr, the Cr content is preferably 80 atomic% or more, may be 85 atomic% or more, and may be 87 atomic% or more, relative to the total atoms of the buffer layer. If the buffer layer contains Cr, the Cr content is preferably 99 atomic% or less, more preferably 95 atomic% or less, and even more preferably 92 atomic% or less, relative to the total atoms of the buffer layer. If the buffer layer contains Ta, the Ta content is preferably 60 atomic% or more, more preferably 70 atomic% or more, and may also be 75 atomic% or more, or 80 atomic% or more, relative to the total atoms of the buffer layer. If the buffer layer contains Ta, the Ta content is preferably 99 atomic% or less, more preferably 95 atomic% or less, and even more preferably 90 atomic% or less, relative to the total atoms of the buffer layer. The buffer layer preferably contains N, and the N content is preferably 40 atomic% or less, more preferably 30 atomic% or less, and may also be 20 atomic% or less, relative to the total atoms of the buffer layer.

[0052] The types and amounts of elements contained in the buffer layer can be measured using the same method as for measuring the types and amounts of elements contained in the absorber membrane.

[0053] The thickness of the buffer layer is preferably 2 nm or more, more preferably 3 nm or more, even more preferably 4 nm or more, and may also be 5 nm or more, or 10 nm or more. Furthermore, the thickness of the buffer layer is preferably 30 nm or less, and more preferably 20 nm or less. The thickness of the buffer layer is determined by XRR.

[0054] The buffer layer can be deposited using known deposition methods such as DC sputtering, magnetron sputtering, and ion beam sputtering. Furthermore, if nitrogen gas is introduced into the atmosphere during deposition, a buffer layer containing nitrogen can be formed by reactive sputtering.

[0055] [Hard Mask Film] The reflective mask blank of the present invention may have a hard mask film on the side opposite to the substrate side of the absorber film. Preferably, the hard mask film is made of a material that has high resistance to dry etching. When a hard mask film is formed on the absorber film, dry etching can be performed even if the minimum line width of the absorber film pattern is reduced. Therefore, it is effective for miniaturizing the absorber film pattern.

[0056] The hard mask film preferably contains one or more elements selected from the group consisting of Al, Si, Ti, Cr, Y, Nb, Mo, Ta, and Hf (hereinafter also referred to as "element X3"). That is, the material constituting the hard mask film preferably contains element X3. The hard mask film may further contain at least one element selected from the group consisting of B, N, and O. Examples of materials constituting the hard mask film include element X3, oxides, nitrides, oxynitrides, carbides, carbonitrides, carbonites, fluorides, and oxyfluorides of element X3. The material constituting the hard mask film may also be a composite compound (for example, a composite oxide) containing two or more elements from element X3.

[0057] For example, Cr-based materials containing Cr as element X3 include materials containing Cr and one or more elements selected from the group consisting of Cr and O, N, C, and H, and more specifically, CrO, CrN, and CrON. The notation "CrON" represents a material containing Cr, O, and N, and the following similar notations have the same meaning. Furthermore, Si-based materials containing Si as element X3 include materials containing Si and one or more elements selected from the group consisting of Si and O, N, C, and H, and more specifically, SiO ２Examples include SiO, SiN, SiO, SiC, SiCO, SiCN, and SiCON.

[0058] The thickness of the hard mask film is preferably 2 nm or more. The thickness of the hard mask film is preferably 30 nm or less, more preferably 25 nm or less, and even more preferably 10 nm or less.

[0059] Hard mask films can be formed using known film deposition methods such as DC sputtering, magnetron sputtering, and ion beam sputtering.

[0060] [Conductive Film] The reflective mask blank of the present invention may have a conductive film on the side of the substrate opposite to the first main surface (second main surface). By providing a conductive film, the reflective mask blank can be handled by an electrostatic chuck. The conductive film preferably has a low sheet resistance. The sheet resistance of the conductive film is preferably 200 Ω / sq. or less, and more preferably 100 Ω / sq. or less. The constituent material of the conductive film can be broadly selected from those described in known literature. For example, a high dielectric constant coating described in Japanese Patent Publication No. 2003-501823, specifically a coating consisting of Si, Mo, Cr, CrON, or TaSi, can be applied. Alternatively, the constituent material of the conductive film may be a Cr compound containing Cr and one or more selected from the group consisting of B, N, O, and C, or a Ta compound containing Ta and one or more selected from the group consisting of B, N, O, and C. The thickness of the conductive film is preferably 10 to 1000 nm, and more preferably 10 to 400 nm. The conductive film may also have a function of adjusting the stress on the second main surface side of the reflective mask blank. That is, the conductive film can adjust the reflective mask blank to be flat by balancing the stress from various films formed on the first main surface side. The conductive film can be formed using known film deposition methods, such as sputtering methods such as DC sputtering, magnetron sputtering, and ion beam sputtering, CVD, vacuum deposition, and electroplating.

[0061] <Method for Manufacturing a Reflective Mask Blank> The present invention provides a method for manufacturing a reflective mask blank comprising, in this order, a substrate, a multilayer reflective film that reflects EUV light, a protective film, and an absorber film. Here, the absorber film contains platinum, and the Rh content in the outermost layer of the protective film on the absorber film side is 50 atomic percent or more relative to the total atoms of the outermost layer. More specifically, the present invention provides a method for manufacturing a reflective mask blank by forming a multilayer reflective film on one main surface of the substrate, forming a protective film having an outermost layer with an Rh content of 50 atomic percent or more, and forming an absorber film containing Pt. The method for forming each component of the reflective mask blank of the present invention is as described above. Furthermore, the method for manufacturing a reflective mask blank of the present invention may include steps for forming the components that the mask blank of the present invention may have as described above.

[0062] <Method for Manufacturing a Reflective Mask and the Reflective Mask> The reflective mask of the present invention is obtained by patterning the absorbent membrane of the reflective mask blank of the present invention. An example of a method for manufacturing a reflective mask will be explained with reference to Figure 2.

[0063] Figure 2(a) shows a state in which a resist pattern 40 has been formed on a reflective mask blank having a substrate 12, a multilayer reflective film 14, a protective film 16, and an absorber film 18 in that order. A known method can be used to form the resist pattern 40. For example, a resist is applied to the absorber film 18 of the reflective mask blank, and exposure and development are performed to form the resist pattern 40. The resist pattern 40 corresponds to a pattern formed on a wafer using a reflective mask. Then, using the resist pattern 40 in Figure 2(a) as a mask, the absorber film 18 is etched to obtain an absorber film pattern 18pt. Next, the resist pattern 40 is removed to obtain the laminate shown in Figure 2(b). Etching of the absorber film 18 can be performed by a known method. For example, dry etching using a fluorine-based gas (fluorine compound) can be used. Examples of fluorine-based gases include CF ４ CHF ３ , C ２ F ６ , C３ F ６ , C ４ F ６ , C ４ F ８ ,CH ２ F ２ ,CH ３ F, C ３ F ８ F ２ SF ６ , and NF ３ Examples include gases such as fluorine-based gases and mixtures thereof. If necessary, in addition to fluorine-based gases, active gases such as oxygen gas and chlorine gas, and inert gases such as nitrogen gas, helium gas, and argon gas may be mixed. In other words, it is preferable to use a gas containing a fluorine compound for dry etching when forming the absorber film pattern 18pt. In the reflective mask blank of the present invention, since the absorber film 18 contains Pt, the processability of the absorber film 18 can be easily improved by dry etching using the above-mentioned fluorine-based gas.

[0064] Furthermore, the resist pattern 40 can be removed by known methods, including removal with a cleaning solution. Examples of cleaning solutions include sulfuric acid-hydrogen peroxide aqueous solution (SPM), sulfuric acid, ammonia water, ammonia-hydrogen peroxide aqueous solution (APM), OH radical cleaning water, and ozonated water.

[0065] Next, as shown in Figure 2(d), a resist pattern 41 corresponding to the frame of the exposure area is formed on the laminate in Figure 2(c), and dry etching is performed using the resist pattern 41 in Figure 2(c) as a mask. Dry etching is carried out until the substrate 12 is reached. After dry etching, the resist pattern 42 is removed to obtain the reflective mask shown in Figure 2(d).

[0066] The reflective mask obtained by patterning the absorber film of the reflective mask blank of the present invention can be suitably applied as a reflective mask used for exposure with EUV light.

[0067] The present invention will be described in more detail below based on examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the examples shown below. Examples 1 to 18 described later are examples, and Examples 19 to 26 are comparative examples.

[0068] <Example 1> First, a Pt film (thickness 35 nm) was formed on a silicon wafer as an absorber film. The Pt film was formed by DC sputtering under the following conditions: Target: Pt target; Sputtering gas: Ar gas; Deposition rate: 0.17 nm / second; Input power density per target area: 4.9 W / cm² ２

[0069] Next, the surface of the obtained absorber film was subjected to plasma treatment to etch the absorber film, and the etching rate of the absorber film was determined. An inductively coupled plasma (ICP) generator was used for the plasma treatment, and the following conditions were met: ICP antenna bias output: 1200W, Substrate bias output: 50W, Etching gas: CF ４ Gas and O ２ Gas mixed gas etching pressure: 0.4 Pa. Under the above conditions, the film thickness before and after etching was measured by XRR, and the etching rate of the absorber film (unit: nm / min) was calculated by dividing the change in film thickness by the etching time.

[0070] Furthermore, a Ru film (thickness 1.0 nm, lower layer) and a Rh film (thickness 2.5 nm, upper layer) were formed on the silicon wafer as protective films in this order. The Ru film and Rh film were formed by ion beam sputtering under the following conditions: Ru film deposition conditions: Target: Ru target, Sputtering gas: Ar gas, Gas pressure: 0.027 Pa, Ion acceleration voltage: 600 V, Deposition rate: 0.056 nm / second Rh film deposition conditions: Target: Rh target, Sputtering gas: Ar gas, Gas pressure: 0.027 Pa, Ion acceleration voltage: 600 V, Deposition rate: 0.077 nm / second

[0071] Next, the surface of the obtained protective film was subjected to plasma treatment to etch it, and the etching rate of the protective film was determined. The plasma treatment conditions were the same as those for the plasma treatment of the absorber film described above.

[0072] The etching rate ratio (the ratio of the etching rate of the absorber film to the etching rate of the protective film) was calculated from the etching rates of the absorber film and the protective film. The calculated etching rate ratio was evaluated according to the following criteria. Note that the above etching rate ratio is calculated as (etching rate of absorber film) / (etching rate of protective film). A: Etching rate ratio of 7 or more B: Etching rate ratio of 4 or more but less than 7 C: Etching rate ratio less than 4 The evaluation results are shown in the table below.

[0073] Furthermore, the crystallinity of the absorber film deposited on the silicon wafer was measured using the procedure described above. More specifically, an XRD measurement was performed to obtain a diffraction chart, and the full width at half maximum of the diffraction peak with the highest intensity was obtained in the range of 2θ from 20 to 50°. In the above measurement, the scanning direction was adjusted so that the diffraction peak of the silicon wafer would not appear in the diffraction chart during the θ / 2θ scan. A Rigaku Mini Flex XRD was used for the above XRD measurement. The X-ray source was CuKα (including CuKα1 and CuKα2), with a tube voltage of 30kV and a tube current of 20mA. A one-dimensional detector was used for the measurement. A 1.0 mmφ microslit and a 1.0 mmφ collimator were used on the X-ray source side. The step width was 0.02°, the step time was 0.2 s / step, and measurements were performed in the range of 2θ from 20 to 80°. The measurement results are shown in the following table, categorized as follows. An A rating is preferred. A: Total half-width is 1.0° or greater. B: Total half-width is less than 1.0°.

[0074] <Examples 2 to 26> Examples 2 to 26 were obtained in the same manner as in Example 1, except that the types of protective films and absorber films were as shown in the table below, and the above evaluation was performed. The elemental ratios of the obtained protective films and absorber films were measured using the method described above, and the values ​​were as shown in the table below. The absorber films in Examples 2 to 26 were deposited by magnetron sputtering using two types of targets. The absorber films in Examples 13, 17, 22, 25, and 26 were deposited by reactive sputtering with oxygen gas introduced into the atmosphere.

[0075] Furthermore, in Examples 4, 12, 20, 21, 23, and 24, instead of forming the Rh protective film as in Example 1, films with the compositions listed in the table below were deposited by magnetron sputtering using two types of targets. That is, after depositing a Ru film (lower layer) as in Example 1, a film with the composition shown in the table below was deposited as the upper layer.

[0076] Furthermore, a reflective mask blank can be obtained by forming a multilayer reflective film on a substrate, forming the protective film of each example on the side of the multilayer reflective film opposite the substrate side, and forming the absorber film of each example on the side of the protective film opposite the substrate side.

[0077] <Results> The composition of the upper layer of the absorber membrane and protective membrane for each example, along with the measurement results and evaluation results described above, are shown in Table 1 below. In Table 1, "at%" represents atomic percent.

[0078]

[0079] The results shown in Table 1 confirm that when the absorber film contains Pt and the Rh content in the outermost layer of the protective film on the absorber film side is 50 atomic percent or more relative to the total atoms of the outermost layer, the ratio of the etching rate of the absorber film to the etching rate of the protective film (etching rate ratio) becomes larger (Examples 1 to 18). On the other hand, when the Rh content in the outermost layer of the protective film on the absorber film side is less than 50 atomic percent relative to the total atoms of the outermost layer, and when the O content is less than 20 atomic percent relative to the total atoms of the absorber film, the etching rate ratio does not become larger (Examples 19 to 26). Furthermore, from a comparison between Example 11 and Example 13, and between Example 16 and Example 17, it was confirmed that the crystallinity becomes lower when the absorber film further contains at least one element selected from the group consisting of B, C, N, and O. Furthermore, comparisons between Example 11 and Examples 8-10, and between Example 18 and Examples 14-16, confirmed that the etching rate ratio becomes larger when the Pt content in the absorber membrane is 80 atomic percent or less relative to the total atoms of the absorber membrane.

[0080] 10 Reflective mask blank 12 Substrate 14 Multilayer reflective film 16 Protective film 18 Absorber film 18pt Absorber film pattern 40, 41 Resist pattern

[0081] Furthermore, the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2024-204644, filed on November 25, 2024, are incorporated herein by reference as disclosure of the present invention.

Claims

1. A reflective mask blank comprising, in this order, a substrate, a multilayer reflective film that reflects EUV light, a protective film, and an absorber film, wherein the absorber film contains platinum, the oxygen atom content of the absorber film is less than 20 atomic percent of the total atoms of the absorber film, and the rhodium content of the outermost layer of the protective film on the absorber film side is 50 atomic percent or more of the total atoms of the outermost layer.

2. The reflective mask blank according to claim 1, wherein the ruthenium content in the outermost layer is less than 30 atomic percent of the total atoms in the outermost layer.

3. The reflective mask blank according to claim 1 or 2, wherein the outermost layer consists solely of rhodium, or comprises rhodium and at least one element selected from the group consisting of ruthenium, niobium, molybdenum, tantalum, iridium, palladium, zirconium, aluminum, yttrium, and titanium.

4. The reflective mask blank according to claim 1 or 2, wherein the absorber film consists solely of platinum, or comprises platinum and at least one element selected from the group consisting of ruthenium, tantalum, tungsten, niobium, and molybdenum.

5. The reflective mask blank according to claim 1 or 2, wherein the absorber film comprises platinum and at least one element selected from the group consisting of ruthenium, tantalum, tungsten, niobium, and molybdenum, and the platinum content in the absorber film is 80 atomic percent or less relative to the total atoms of the absorber film.

6. The reflective mask blank according to claim 1 or 2, wherein the absorbent film comprises platinum and at least one element selected from the group consisting of tantalum and tungsten, and the platinum content in the absorbent film is 80 atomic percent or less relative to the total atoms of the absorbent film.

7. The reflective mask blank according to claim 1 or 2, wherein the absorbent film further comprises at least one element selected from the group consisting of boron, carbon, nitrogen, and oxygen.

8. The reflective mask blank according to claim 1 or 2, wherein the protective film contains 50 atomic percent or more of rhodium in a layer with a film thickness of 0.5 to 5.0 nm.

9. A reflective mask having an absorbent film pattern formed by patterning the absorbent film of the reflective mask blank according to claim 1 or 2.

10. A method for manufacturing a reflective mask, comprising the step of patterning the absorbent membrane of the reflective mask blank according to claim 1 or 2 to form an absorbent membrane pattern.

11. A method for manufacturing a reflective mask blank having a substrate, a multilayer reflective film, a protective film, and an absorber film in this order, wherein the multilayer reflective film is formed on one main surface of the substrate, the protective film having an outermost layer with a rhodium content of 50 atomic percent or more is formed on the multilayer reflective film, and the absorber film containing platinum is formed on the protective film.

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