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

Abstract

The purpose of the present invention is to provide a reflective mask blank having an absorber film that has a low refractive index n for EUV light, a high extinction coefficient k for EUV light, and excellent SPM resistance. An absorber film (18) of a reflective mask blank (10) contains palladium and at least one element X selected from the group consisting of ruthenium, iridium, and platinum. The total content of palladium and the element X in the absorber film (18) is 80 at% or more with respect to the total metal atoms contained in the absorber film (18). When the element X is only ruthenium, the content of the element X in the absorber film (18) is 20-75 at% with respect to the total atoms in the absorber film (18). When the element X contains at least one of iridium or platinum, the content of the element X in the absorber film (18) is 30 at% or more with respect to the total atoms in the absorber film (18).

Description

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 absorber film that absorbs EUV light is patterned on the multilayer reflective film.

[0004] EUV light incident on a reflective mask from the illumination optical system of an exposure apparatus is reflected in areas without an absorber film (apertures) and absorbed in areas with an 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. As an absorber film, for example, Patent Document 1 shows absorber films made of various alloys exhibiting predetermined optical property relationships.

[0005] Japanese Patent Publication No. 2021-101258

[0006] For use as a reflective mask, the absorber film of a reflective mask blank is required to have excellent optical properties, specifically a low refractive index n for EUV light and a large extinction coefficient k for EUV light. When examining the palladium and ruthenium-containing material specifically disclosed in Patent Document 1, it was found that the extinction coefficient k did not meet the desired level and that improvement was necessary. Furthermore, when a reflective mask blank is patterned and used as a mask, sulfuric acid peroxide (SPM) may be used as a processing solution during mask manufacturing, and the absorber film is required to have excellent SPM resistance.

[0007] The present invention has been made in view of the above problems and aims to provide a reflective mask blank having an absorber film with a small refractive index n for EUV light, a large extinction coefficient k for EUV light, and excellent SPM resistance. The present invention also aims to provide a reflective mask and a method for manufacturing a reflective mask.

[0008] As a result of diligent research into the above-mentioned problems, the present inventors have found that an absorber film containing palladium and at least one element X selected from the group consisting of ruthenium, iridium, and platinum in a predetermined ratio has a low refractive index n for EUV light, a high extinction coefficient k for EUV light, and excellent SPM resistance, leading to the present invention.

[0009] In other words, the inventors have found that the above problem can be solved by the following configuration: [1] A reflective mask blank having, in this order, a substrate, a multilayer reflective film that reflects EUV light, and an absorber film, wherein the absorber film contains palladium and at least one element X selected from the group consisting of ruthenium, iridium, and platinum, the total content of palladium and element X in the absorber film is 80 atomic percent or more with respect to the total metal atoms contained in the absorber film, if element X is only ruthenium, the content of element X in the absorber film is 20 atomic percent or more and 75 atomic percent or less with respect to the total atoms of the absorber film, and if element X includes at least one of iridium and platinum, the content of element X in the absorber film is 30 atomic percent or more with respect to the total atoms of the absorber film. [2] The reflective mask blank according to [1], wherein the extinction coefficient of the absorber film at a wavelength of 13.5 nm is 0.023 or greater. [3] The reflective mask blank according to [2], wherein the extinction coefficient of the absorber film at a wavelength of 13.5 nm is 0.025 or greater. [4] The reflective mask blank according to any one of [1] to [3], wherein the refractive index of the absorber film at a wavelength of 13.5 nm is 0.910 or less. [5] The reflective mask blank according to any one of [1] to [4], wherein the refractive index of the absorber film at a wavelength of 13.5 nm is 0.900 or less. [6] The reflective mask blank according to any one of [1] to [5], wherein the palladium content in the absorber film is 25 atomic% or more and 60 atomic% or less relative to the total atoms of the absorber film, and the ruthenium content in the absorber film is 40 atomic% or more and 75 atomic% or less relative to the total atoms of the absorber film. [7] A reflective mask blank according to any one of [1] to [5], wherein the palladium content in the absorber membrane is 5 atomic percent or more and 70 atomic percent or less relative to the total atoms of the absorber membrane, and the iridium content in the absorber membrane is 30 atomic percent or more and 95 atomic percent or less relative to the total atoms of the absorber membrane.[8] A reflective mask blank according to any one of [1] to [5], wherein the palladium content in the absorber film is 5 atomic percent or more and 70 atomic percent or less relative to the total atoms of the absorber film, and the platinum content in the absorber film is 30 atomic percent or more and 95 atomic percent or less relative to the total atoms of the absorber film. [9] A reflective mask blank according to any one of [1] to [8], wherein the palladium content in the absorber film is 60 atomic percent or less relative to the total atoms of the absorber film.

[10] A reflective mask blank according to any one of [1] to [9], wherein the absorber film contains at least one element selected from the group consisting of nitrogen, boron, oxygen, and carbon.

[11] A reflective mask blank according to any one of [1] to [9], further comprising a protective film between the absorber film and the multilayer reflective film, wherein the protective film contains rhodium.

[12] A reflective mask having an absorbent membrane pattern formed by patterning the absorbent membrane of a reflective mask blank described in any one of [1] to

[11] .

[13] A method for manufacturing a reflective mask, comprising the step of patterning the absorbent membrane of a reflective mask blank described in any one of [1] to

[11] .

[0010] According to the present invention, a reflective mask blank can be provided that has an absorber film with a low refractive index n for EUV light, a high extinction coefficient k for EUV light, and excellent SPM resistance. Furthermore, according to the present invention, a reflective mask and a method for manufacturing a reflective mask can also be provided.

[0011] This is a schematic cross-sectional view showing an example of an embodiment of the reflective mask blank of the present invention. This is a schematic cross-sectional view showing an example of a manufacturing process for a reflective mask using the reflective mask blank of the present invention.

[0012] The meanings of terms used in this invention are as follows: A numerical range indicated by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits. In this specification, elements such as boron, carbon, nitrogen, oxygen, silicon, titanium, chromium, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, beryllium, and platinum may be represented by their respective element symbols (B, C, N, O, Si, Ti, Cr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Hf, Ta, W, Re, Os, Ir, Be, and Pt, etc.). In this specification, silicon (Si) is included in the metallic elements.

[0013] <Reflective Mask Blank> The reflective mask blank of the present invention is a reflective mask blank having, in this order, a substrate, a multilayer reflective film that reflects EUV light, and an absorber film, wherein the absorber film contains Pd and at least one element X selected from the group consisting of Ru, Ir, and Pt, the total content of Pd and element X in the absorber film is 80 atomic percent or more with respect to the total metal atoms contained in the absorber film, if element X is only Ru, the content of element X in the absorber film is 20 atomic percent or more and 75 atomic percent or less with respect to the total atoms of the absorber film, and if element X contains at least one of Ir and Pt, the content of element X in the absorber film is 30 atomic percent or more with respect to the total atoms of the absorber film.

[0014] The reflective mask blank of the present invention will be described while referring to the drawings. FIG. 1 is a cross-sectional view showing an example of an embodiment of the reflective mask blank of the present invention. The reflective mask blank 10 shown in FIG. 1 has a substrate 12, a multilayer reflective film 14, a protective film 16, and an absorber film 18 in this order. Note that the reflective mask blank 10 shown in FIG. 1 may have a hard mask film, which will be described later, on the side opposite to the substrate 12 side of the absorber film 18. Also, the reflective mask blank 10 shown in FIG. 1 may have a conductive film, which will be described later, on the side opposite to the multilayer reflective film 14 side of the substrate 12. The reflective mask blank 10 shown in FIG. 1 has a protective film 16, but the protective film 16 may be omitted.

[0015] In the absorber film of the reflective mask blank of the present invention, the refractive index n with respect to EUV light (hereinafter, also simply referred to as "refractive index n") is small, the extinction coefficient k with respect to EUV light (hereinafter, also simply referred to as "extinction coefficient k") is large, and it has excellent SPM resistance. Although the details of this reason are unclear, the present inventor speculates as follows. Pd has a small refractive index n, a large extinction coefficient k, and excellent optical properties, but lacks SPM resistance. The absorber film of the reflective mask blank of the present invention contains, in addition to the above Pd, an element X having excellent SPM resistance and a relatively small refractive index n at a predetermined content, so it is considered that both desired optical properties and SPM resistance can be achieved.

[0016] Hereinafter, the configuration of the reflective mask blank of the present invention will be described in detail.

[0017] [Substrate] The substrate of the reflective mask blank of the present invention preferably has a small thermal expansion coefficient. When the thermal expansion coefficient of the substrate is small, it is possible to suppress the occurrence of distortion in the absorber film pattern due to heat during exposure with EUV light. The thermal expansion coefficient of the substrate is preferably 0 ± 1.0 × 10 －７ / °C at 20°C, and more preferably 0 ± 0.3 × 10 －７ / °C. As a material having a small thermal expansion coefficient, SiO ２ -TiO ２Examples of the substrate include glass, etc., but are not limited thereto. Crystallized glass in which a β-quartz solid solution is precipitated, fused silica, metallic silicon, and substrates such as metals can also be used. SiO ２ -TiO ２ -based glass preferably uses fused silica 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 almost 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 .

[0018] 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 root mean square roughness Rq. The surface roughness can be measured with 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 excellent pattern transfer accuracy and position accuracy of the reflective mask obtained using the reflective mask blank. Specifically, the substrate preferably has a flatness of 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less in a predetermined region (for example, a region of 132 mm × 132 mm) of the first main surface. The flatness can be measured with a flatness measuring instrument manufactured by Fujinon Corporation. The size and thickness of the substrate, etc. can be appropriately determined according to the design of the mask, etc. Examples of the dimensions of the substrate include an outer shape of 6 inches (152 mm) square and a thickness of 0.25 inches (6.3 mm). The substrate is often rectangular (rectangular) or square. The substrate preferably has high rigidity in terms of preventing deformation due to the film stress of the film (such as the multilayer reflective film and the absorber film) formed on the substrate. For example, the Young's modulus of the substrate is preferably 65 GPa or more.

[0019] [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 desired characteristics as the reflective film of an EUV mask blank. It is preferable that the above multilayer reflective film has a high reflectivity of EUV light. Specifically, when EUV light is incident on the multilayer reflective film at an incident angle of 6°, the maximum value of the reflectivity of EUV light near a wavelength of 13.5 nm is preferably 60% or more, and more preferably 65% or more. Even when a protective film is laminated on the multilayer reflective film, similarly, the maximum value of the reflectivity of EUV light near a wavelength of 13.5 nm is preferably 60% or more, and more preferably 65% or more.

[0020] From the viewpoint of achieving a high reflectivity of EUV light, the multilayer reflective film usually uses a multilayer reflective film in which a high refractive index layer showing a high refractive index with respect to EUV light and a low refractive index layer showing a low refractive index with respect to EUV light are alternately laminated a plurality of times. The multilayer reflective film may be laminated with a plurality of cycles with a laminated structure in which a high refractive index layer and a low refractive index layer are laminated in this order from the substrate side as one cycle, or a laminated structure in which a low refractive index layer and a high refractive index layer are laminated in this order from the substrate side as one cycle. As the high refractive index layer, a layer containing Be or a layer containing Si can be used. As the material containing Si, Si alone, and Si compounds containing at least one or more 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 a high reflectivity of EUV light can be obtained. As the low refractive index layer, a layer containing at least one 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 above high refractive index layer, and Mo is widely used for the low refractive index layer. That is, the Mo / Si multilayer reflective film is the most common. However, the multilayer reflective film is not limited to this, and Ru / Si multilayer reflective films, Mo / Be multilayer reflective films, Mo compound / Si compound multilayer reflective films, Si / Mo / Ru multilayer reflective films, Si / Mo / Ru / Mo multilayer reflective films, Si / Ru / Mo multilayer reflective films, and Si / Ru / Mo / Ru multilayer reflective films can also be used.

[0021] 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 materials used and the required EUV light reflectance of the multilayer reflective film. Taking a Mo / Si multilayer reflective film as an example, in order 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. The reflectance of the multilayer reflective film for EUV light with an incident angle θ of 6° is preferably 60% or more, and more preferably 65% ​​or more.

[0022] 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. If the multilayer reflective film is a Mo / Si multilayer reflective film, for example, it can be fabricated by ion beam sputtering in the following way: First, a Si layer of a predetermined thickness is deposited on a 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.

[0023] [Protective Film] The reflective mask blank of the present invention may have 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 the etching process. It is also preferable that the protective film protects the multilayer reflective film when the hard mask film described later is removed.

[0024] The protective film preferably contains at least one element selected from the group consisting of Si, Ru, and Rh. The protective film may also preferably contain Rh. If the protective film contains Rh, the Rh content is preferably 50 atomic percent or more relative to the total atoms of the protective film. Specific examples of protective film materials include elemental Ru metal, Ru alloys containing Ru and one or more metals selected from the group consisting of Si, Y, Ti, Zr, Nb, Mo, Rh, Pd, Ta, and Ir, elemental Rh metal, and Rh alloys containing Rh and one or more metals selected from the group consisting of Si, Y, Ti, Zr, Nb, Mo, Ru, Pd, Ta, and Ir. Adding Ru, Nb, Mo, Zr, Y, or Ti to Rh can suppress the increase in refractive index while reducing the extinction coefficient, making it easier to increase the reflectivity of EUV light. Furthermore, adding Ta, Ir, Pd, or Y to Rh tends to improve resistance to etching processes. Suitable materials for the protective film include elemental Al metal, nitrides containing Al and N, and Al ２ O ３ Other materials can also be used. Among these, Ru metal alone, Ru alloy, Rh metal alone, or Rh alloy are preferred as the material for the protective film.

[0025] The protective film may contain at least one element selected from the group consisting of B, C, N, and O.

[0026] The types and content of elements contained in the protective film are obtained by X-ray photoelectron spectroscopy (XPS). When measuring the types and content of elements in the protective film using XPS, the layer on the opposite side of the protective film from the substrate side is removed by sputtering or other means before measurement. The detailed XPS measurement method can be the same as that used for the absorber film in the subsequent step.

[0027] The thickness of the protective film is not particularly limited as long as it can perform its function as a protective film. In terms of maintaining the reflectance of EUV light reflected by the multilayer reflective film, 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. Furthermore, in terms of etching resistance, 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. In particular, it is preferable that the material of the protective film is elemental Ru metal, Ru alloy, elemental Rh metal, or Rh alloy, and that the thickness of the protective film satisfies the above preferred range. The thickness of the protective film is determined by X-ray reflectivity (XRR). Rigaku's Smart Lab HTP is used for XRR measurement. CuKα rays will be used as the X-ray source, with a tube voltage of 40 kV and a tube current of 30 mA. The accompanying software (GlobalFit) will be used for analysis.

[0028] The protective film may be a single layer or a multilayer film consisting of multiple layers. If the protective film is a multilayer film, it is preferable that each layer constituting the multilayer film is made of the material described above. Also, if the protective film is a multilayer film, it is preferable that the total thickness of the multilayer film satisfies the preferred range described above. If the protective film is a multilayer film, it is preferable that the layer of the multilayer film that is located closest to the absorber film contains Rh. Also, if the layer of the multilayer film that is located closest to the absorber film contains Rh, it is preferable that at least one of the other layers contains Ru. In particular, the protective film is a multilayer film comprising a first layer and a second layer from the absorber film side, wherein the first layer contains 50 atomic percent or more of Rh relative to the total atoms of the first layer, and the second layer contains 50 atomic percent or more of Ru relative to the total atoms of the second layer.

[0029] 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.

[0030] [Absorber Film] The absorber film of the reflective mask blank of the present invention is required to have a high contrast between the EUV light reflected by the multilayer reflective film and the EUV light reflected by the absorber film when a pattern is formed on the absorber film. The absorber film with a pattern formed on it (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 while interfering with the EUV light from the multilayer reflective film to produce contrast. In other words, the absorber film may be a phase-shift film.

[0031] The absorbent membrane contains Pd and at least one element X selected from the group consisting of Ru, Ir, and Pt. In the absorbent membrane, the total content of Pd and element X is 80 atomic percent or more, preferably 85 atomic percent or more, more preferably 90 atomic percent or more, and even more preferably 95 atomic percent or more, relative to the total metal atoms contained in the absorbent membrane. The upper limit may be 100 atomic percent or less. Alternatively, in the absorbent membrane, the total content of Pd and element X is preferably 70 atomic percent or more, more preferably 80 atomic percent or more, and even more preferably 90 atomic percent or more, relative to the total atoms of the absorbent membrane. The upper limit may be 100 atomic percent or less. In other words, the absorbent membrane may be a membrane composed of Pd and element X.

[0032] The Pd content in the absorbent membrane is preferably 65 atomic percent or less, and more preferably 60 atomic percent or less, relative to the total atoms of the absorbent membrane, in terms of superior SPM resistance.

[0033] Element X may be one element or two or more elements, but it is preferable that it be one element. When element X is only Ru (i.e., element X does not contain either Ir or Pt), the content of element X in the absorber film is 20 atomic% or more relative to the total atoms of the absorber film, preferably 25 atomic% or more, more preferably 30 atomic% or more, and even more preferably 40 atomic% or more, in terms of superior SPM resistance. Also, when element X is only Ru, the content of element X is 75 atomic% or less relative to the total atoms of the absorber film, preferably 70 atomic% or less, and more preferably 60 atomic% or less, in terms of superior optical properties. When element X contains at least one of Ir and Pt, the content of element X in the absorber film is 30 atomic% or more relative to the total atoms of the absorber film, preferably 40 atomic% or more, and more preferably 50 atomic% or more, in terms of superior SPM resistance. Furthermore, if element X includes at least one of Ir and Pt, the content of element X in the absorber film is preferably 95 atomic% or less, more preferably 90 atomic% or less, even more preferably 80 atomic% or less, and particularly preferably 70 atomic% or less, in terms of having a smaller refractive index n.

[0034] When the absorber membrane contains Ru, the Ru content in the absorber membrane is preferably 20 atomic% or more, more preferably 25 atomic% or more, even more preferably 30 atomic% or more, and particularly preferably 40 atomic% or more, relative to the total atoms of the absorber membrane, in terms of superior SPM resistance. Furthermore, when the absorber membrane contains Ru, the Ru content in the absorber membrane is preferably 75 atomic% or less, more preferably 70 atomic% or less, and particularly preferably 60 atomic% or less, relative to the total atoms of the absorber membrane, in terms of superior optical properties. When the absorber membrane contains Ru, the Pd content in the absorber membrane is preferably 80 atomic% or less, more preferably 75 atomic% or less, even more preferably 70 atomic% or less, and particularly preferably 60 atomic% or less, relative to the total atoms of the absorber membrane, in terms of superior SPM resistance. Furthermore, when the absorbent film contains Ru, the Pd content in the absorbent film is preferably 25 atomic% or more, more preferably 30 atomic% or more, and even more preferably 40 atomic% or more, relative to the total atoms of the absorbent film, in terms of superior optical properties. In particular, when the absorbent film contains Ru, the Ru content in the absorbent film is preferably 25 atomic% to 75 atomic%, more preferably 40 atomic% to 75 atomic%, and even more preferably 40 atomic% to 70 atomic%, relative to the total atoms of the absorbent film. Furthermore, when the absorbent film contains Ru, the Pd content in the absorbent film is preferably 25 atomic% to 75 atomic%, and even more preferably 25 atomic% to 60 atomic%, relative to the total atoms of the absorbent film.

[0035] When the absorber membrane contains Ir, the Ir content in the absorber membrane is preferably 30 atomic% or more, more preferably 40 atomic% or more, and even more preferably 50 atomic% or more, relative to the total atoms of the absorber membrane, in terms of superior SPM resistance. Furthermore, when the absorber membrane contains Ir, the Ir content in the absorber membrane is preferably 95 atomic% or less, more preferably 90 atomic% or less, even more preferably 80 atomic% or less, and particularly preferably 60 atomic% or less, relative to the total atoms of the absorber membrane, in terms of superior optical properties. When the absorber membrane contains Ir, the Pd content in the absorber membrane is preferably 70 atomic% or less, more preferably 60 atomic% or less, and even more preferably 50 atomic% or less, relative to the total atoms of the absorber membrane, in terms of superior SPM resistance. Furthermore, when the absorber film contains Ir, the Pd content in the absorber film is preferably 5 atomic% or more, more preferably 10 atomic% or more, even more preferably 20 atomic% or more, and particularly preferably 40 atomic% or more, relative to the total atoms of the absorber film, in terms of superior optical properties. In particular, when the absorber film contains Ir, the Ir content in the absorber film is preferably 30 atomic% to 95 atomic%, more preferably 40 atomic% to 95 atomic%, and even more preferably 40 atomic% to 80 atomic%, relative to the total atoms of the absorber film. Furthermore, when the absorber film contains Ir, the Pd content in the absorber film is preferably 5 atomic% to 70 atomic%, and even more preferably 5 atomic% to 60 atomic%, relative to the total atoms of the absorber film.

[0036] When the absorbent membrane contains Pt, the Pt content in the absorbent membrane is preferably 30 atomic% or more, more preferably 40 atomic% or more, and even more preferably 50 atomic% or more, relative to the total atoms of the absorbent membrane, in terms of superior SPM resistance. Furthermore, when the absorbent membrane contains Pt, the Pt content in the absorbent membrane is preferably 95 atomic% or less, more preferably 90 atomic% or less, even more preferably 80 atomic% or less, and particularly preferably 70 atomic% or less, relative to the total atoms of the absorbent membrane, in terms of a smaller refractive index n. When the absorbent membrane contains Pt, the Pd content in the absorbent membrane is preferably 70 atomic% or less, more preferably 60 atomic% or less, and even more preferably 50 atomic% or less, relative to the total atoms of the absorbent membrane, in terms of superior SPM resistance. Furthermore, when the absorbent membrane contains Pt, the Pd content in the absorbent membrane is preferably 5 atomic% or more, more preferably 10 atomic% or more, even more preferably 20 atomic% or more, and particularly preferably 30 atomic% or more, relative to the total atoms of the absorbent membrane, in terms of having a smaller refractive index n. In particular, when the absorbent membrane contains Pt, the Pt content in the absorbent membrane is preferably 30 atomic% to 95 atomic% and more preferably 40 atomic% to 95 atomic% relative to the total atoms of the absorbent membrane. Furthermore, when the absorbent membrane contains Pt, the Pd content in the absorbent membrane is preferably 5 atomic% to 70 atomic% and more preferably 5 atomic% to 70 atomic% relative to the total atoms of the absorbent membrane.

[0037] The absorber membrane may contain elements other than Pd, Ru, Ir, and Pt. Examples of other elements include other metallic elements and nonmetallic elements. Examples of other metallic elements include Mo, Nb, Ag, Ni, Co, Al, Cr, W, Si, Sn, Ta, Ti, Zr, V, and Rh. The content of other metallic elements in the absorber membrane is preferably 10 atomic percent or less, more preferably 5 atomic percent or less, and even more preferably 3 atomic percent or less, relative to the total atoms of the absorber membrane. It is also preferable that the content of other metallic elements in the absorber membrane be 0 atomic percent, that is, it is preferable that it does not contain any metallic elements other than Pd, Ru, Ir, and Pt. As nonmetallic elements, at least one element selected from the group consisting of N, O, B, and C is preferred, with N being more preferred. Since the crystallinity of the absorber membrane tends to decrease, it is also preferable for the absorber membrane to contain nonmetallic elements. When the absorber membrane contains nonmetallic elements, the total content of the nonmetallic elements is preferably 1 to 30 atomic percent, more preferably 1 to 20 atomic percent, even more preferably 1 to 10 atomic percent, and particularly preferably 1 to 5 atomic percent, relative to the total atoms of the absorber membrane.

[0038] Furthermore, if the reflective mask blank of the present invention has a hard mask film as described later, it is preferable that the absorber film does not contain metal elements contained in the hard mask film.

[0039] The types and content of elements contained in the absorber film can be measured by XPS. When measuring the types and content of elements in an absorber film using XPS, the layer on the opposite side of the absorber film from the substrate side should be removed by sputtering or similar methods before measurement. A detailed measurement method is described below.

[0040] 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 the measurement holder so that the absorber film side (or the hard mask film side if the reflective mask blank has a hard mask film) is the measurement surface. After the measurement holder is brought into the above instrument, 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 using a separately prepared sample. After removing a portion of the absorber film, the removed portion is irradiated with X-rays (monochromatic AlKα rays), 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. The analysis involves first performing a wide scan in the binding energy range of 1000 to 0 eV to identify the elements present, and then performing a narrow scan depending on the elements present (e.g., Ru and Pd). The narrow scan is performed, for example, with a pass energy of 58.7 eV, an energy step of 0.1 eV, a time / step of 50 ms, and 5 integrations. 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 2 integrations. The content of each element in the absorber film is determined by analyzing the spectrum obtained from the narrow scan during the XPS analysis using the above procedure, using relative sensitivity coefficients specific to each element and each orbital. Alternatively, the analysis may be performed using the same procedure as above with a model sample formed under the same conditions as those used to form the absorber film.

[0041] If the content of each element cannot be separated and identified by the above XPS, the content of each element in the absorber membrane (especially the content of nonmetallic elements) may be measured using RBS (Rutherford Back-Scattering Spectroscopy).

[0042] When an absorber film pattern is used as a binary mask, it is preferable that the absorber film absorbs EUV light and has 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 13.5 nm is preferably 2% or less. 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. The film thickness of the absorber film is determined by XRR.

[0043] When an absorber film pattern is used as a phase shift mask, the reflectivity of the absorber film to EUV light is preferably 2% or more, and more preferably 9-15% in order to obtain a sufficient phase shift effect. Using an absorber film pattern as a phase shift mask improves the contrast of the optical image on the wafer and increases the exposure margin. When an absorber film pattern is used as a phase shift mask, the film thickness of the absorber film is preferably 30-75 nm, and more preferably 35-55 nm. The film thickness of the absorber film is determined by XRR.

[0044] The refractive index n of the absorber film at a wavelength of 13.5 nm is preferably 0.860 or higher, more preferably 0.870 or higher, and even more preferably 0.880 or higher. Furthermore, the refractive index n of the absorber film at a wavelength of 13.5 nm is preferably 0.910 or lower, and more preferably 0.900 or lower, in that it allows for a thinner film thickness 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 0.023 or higher, more preferably 0.024 or higher, even more preferably 0.025 or higher, and particularly preferably 0.026 or higher, in that it allows for easier adjustment of the reflectance of the absorber film. Furthermore, the extinction coefficient k of the absorber film at a wavelength of 13.5 nm is preferably 0.065 or lower, more preferably 0.060 or lower, and even more preferably 0.055 or lower, in that it allows for easier adjustment of the reflectance of the absorber film. The refractive index n and extinction coefficient k mentioned above can be values ​​from the database of the Center for X-Ray Optics, Lawrence Berkeley National Laboratory, or values ​​calculated from the "dependence of reflectance on the angle of incidence" 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 -cos ２ θ) １／２ ) / (sinθ+((n+ik) ２ -cos ２ θ) １／２ ) | ... (1) By measuring multiple combinations of incident angle θ and reflectance R, and fitting the multiple measurement data to minimize the error between equation (1), the refractive index n and extinction coefficient k can be calculated.

[0045] The absorber film is preferably low in crystallinity, and more preferably amorphous. Low crystallinity of the absorber film allows for higher smoothness and flatness. High 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. The crystalline state of the absorber film can be confirmed by X-ray diffraction (XRD).

[0046] The absorber film may be a single layer or a multilayer film consisting of multiple layers. When the absorber film is a single layer, the number of steps in mask blank manufacturing is reduced, resulting in superior production efficiency. When 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).

[0047] Absorber films can be formed using known film deposition methods such as DC sputtering, magnetron sputtering, and ion beam sputtering. For example, when forming a PdRu film as an absorber film using magnetron sputtering, a Pd target and a Ru target can be used, and sputtering can be performed by supplying Ar gas to form the absorber film. Also, when forming a PdRu film, targets containing Pd and Ru may be used. Furthermore, when forming a film containing at least one element selected from the group consisting of N and O as an absorber film, N may be added to the sputtering gas. ２ Gas and O ２ It is sufficient to introduce at least one of the gases. ２ Gas and O ２ By adjusting the amount of at least one of the gases introduced, the amount of at least one element selected from the group consisting of N and O contained in the formed membrane can be adjusted.

[0048] [Hard Mask Film] The reflective mask blank of the present invention may also preferably have a hard mask film on the side opposite to the substrate side of the absorber film. When the reflective mask blank has a hard mask 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.

[0049] The hard mask film preferably contains one or more metallic elements selected from the group consisting of Cr, Al, Si, Ti, Y, Nb, Mo, Ta, Ru, and Hf (hereinafter also referred to as "element Y"). The total content of element Y in the hard mask film is preferably 30 atomic% or more, more preferably 50 atomic% or more, even more preferably 60 atomic% or more, and particularly preferably 70 atomic% or more, relative to the total atoms of the hard mask film. The upper limit may be 100 atomic%. That is, the hard mask film may be a film consisting only of element Y. The total content of element Y in the hard mask film may be 99 atomic% or less, or 95 atomic% or less.

[0050] The hard mask film may contain elements other than element Y. It is also preferable that the hard mask film contain at least one element selected from the group consisting of B, N, C, and O.

[0051] Materials that constitute the hard mask film include element Y, nitrogen oxides of element Y, nitrides, oxynitrides, carbides, carbonitrides, carbonites, fluorides, and oxyfluorides. The material constituting the hard mask film may also be a composite compound (for example, a composite oxide) containing two or more elements of element Y.

[0052] Examples of Cr-based materials containing Cr include materials containing Cr, and at least one element selected from the group consisting of Cr, O, N, C, and H. More specifically, examples include CrO, CrN, and CrON. The notation "CrON" represents a material containing Cr, O, and N, and the following similar notations have the same meaning. Examples of Al-based materials containing Al include materials containing Al, and at least one element selected from the group consisting of Al, O, and N. More specifically, examples include Al and AlN. Examples of Si-based materials containing Si include materials containing Si, and at least one element selected from the group consisting of Si, O, N, C, and H. More specifically, examples include SiO ２ Examples include SiO, SiN, SiO, SiC, SiCO, SiCN, and SiCON.

[0053] The thickness of the hard mask film is preferably 2 nm or more. Preferably, the thickness of the hard mask film is 30 nm or less, more preferably 25 nm or less, and even more preferably 10 nm or less. The thickness of the hard mask film is determined by XRR.

[0054] Hard mask films can be formed using known film deposition methods such as DC sputtering, magnetron sputtering, and ion beam sputtering. For example, when forming a Cr film as a hard mask film, a Cr target can be used, and sputtering can be performed by supplying Ar gas to form the hard mask film.

[0055] [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 described above (hereinafter also referred to as the "second main surface"). Having a conductive film allows the reflective mask blank to 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.

[0056] The reflective mask blank of the present invention can be manufactured, for example, by forming the multilayer reflective film on the substrate and forming an absorber film on the multilayer reflective film. Furthermore, if the reflective mask blank of the present invention has a protective film, it can be manufactured, for example, by forming the multilayer reflective film on the substrate, forming a protective film on the multilayer reflective film, and forming the absorber film on the protective film. If the reflective mask blank of the present invention has a hard mask film, the manufacturing process may include a step of forming the hard mask film on the absorber film. The method for forming each layer is as described above.

[0057] <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.

[0058] 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 the pattern formed on the wafer using a reflective mask. Then, using the resist pattern 40 in Figure 2(a) as a mask, the absorber film 18 is etched and patterned, and the resist pattern 40 is removed to obtain a laminate having the absorber film pattern 18pt shown in Figure 2(b). Next, as shown in Figure 2(c), a resist pattern 41 corresponding to the frame of the exposure area is formed on the laminate in Figure 2(b), and dry etching is performed using the resist pattern 41 in Figure 2(c) as a mask. Dry etching is performed until the substrate 12 is reached. After dry etching, the resist pattern 41 is removed to obtain the reflective mask shown in Figure 2(d).

[0059] Dry etching for forming the absorber film pattern 18pt can be performed using a Cl-based gas or a F-based gas. Examples of Cl-based gases include Cl ２ SiCl ４ , CHCl ３ , CCl ４ , and BCl ３ Examples of gases include those listed above, as well as mixtures thereof. If necessary, inert gases such as nitrogen, helium, and argon may be added. Examples of F-series gases include CF ４ CHF ３ , C ２ F ６ , C ３ 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 gases and mixed gases thereof. If necessary, in addition to fluorine 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. Among these, it is preferable to include oxygen gas as the active gas. The etching gas may be plasma-generated and used to etch the absorber film 18.

[0060] The resist patterns 40 and 41 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.

[0061] If the reflective mask blank has a hard mask film, the hard mask film may be patterned using the resist pattern 40 as a mask, and dry etching may be performed using the pattern of the hard mask film as a mask. The patterning of the hard mask film can be done by known methods, for example, dry etching with an oxygen-containing gas or a chlorine-containing gas (Cl-based gas). If the reflective mask blank has a hard mask film, a step to remove the hard mask film may be performed. In addition, the hard mask film may be removed simultaneously in the step to remove the resist pattern 40 or 41 described above. As a method for removing the hard mask film, for example, it can be done by the same method as etching the hard mask film described above.

[0062] The reflective mask obtained by patterning the absorber film of the reflective mask blank of the present invention has the absorber film pattern described above. The reflective mask of the present invention can be suitably applied as a reflective mask used for exposure with EUV light.

[0063] The present invention will be described in detail below with reference to examples. Examples 1 to 14 are examples, and Examples 15 to 20 are comparative examples. However, the present invention is not limited to these examples.

[0064] <Example 1> First, we will explain the procedure for obtaining the reflective mask blank shown in Example 1 as a representative example.

[0065] [Substrate] First, as a substrate, SiO ２ -TiO ２ A glass substrate (6 inches (152 mm) square, 6.3 mm thick) was prepared. This glass substrate has a coefficient of thermal expansion of 0.02 × 10⁻¹⁰ at 20°C. －７ The temperature is / °C, the Young's modulus is 67 GPa, the Poisson's ratio is 0.17, and the specific stiffness is 3.07 × 10⁻⁶. ７ I understand ２ / s ２The quality assurance area of ​​the first main surface of the substrate had a root mean square roughness (Rq) of 0.15 nm or less and a flatness of 100 nm or less achieved by polishing. A 100 nm thick Cr film was deposited on the second main surface of the substrate using magnetron sputtering. The sheet resistance of the Cr film was 100 Ω / □.

[0066] [Multilayer Reflective Film] Next, a Mo / Si multilayer reflective film was formed on the first main surface of the substrate. The Mo / Si multilayer reflective film was obtained by repeatedly depositing a Si film (thickness 4.5 nm) and a Mo film (thickness 2.3 nm) 40 times using the ion beam sputtering method, and after the 40th Mo film was formed, a Si film (thickness 4.5 nm) was further formed. The total thickness of the Mo / Si multilayer reflective film was 276.5 nm ((4.5 nm + 2.3 nm) × 40 + 4.5 nm).

[0067] [Protective Film] On the multilayer reflective film formed by the above procedure, a Ru film (thickness 1.0 nm) and a Rh film (thickness 2.5 nm) were formed in this order as protective films. 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

[0068] [Absorbing Film] A PdRu film was formed as an absorbing film on the protective film formed by the above procedure. The PdRu film was formed by DC sputtering under the following conditions: • Target: Ru target and Pd target • Sputtering gas: Ar gas • Input power density per unit area of ​​Ru target: 4.4 W / cm² ２ - Input power density per Pd target area: 7.4 W / cm² ２ ・Film formation rate: 0.52nm / sec

[0069] <Examples 2-20> Reflective mask blanks for each example were obtained in the same manner as in Example 1, except that the film deposition conditions and target for the absorber film were changed to achieve the composition shown in Table 1 below. Note that the absorber film of the reflective mask blank in Example 6 was prepared by adding N in the sputtering gas. ２ The film was deposited by introducing a gas.

[0070] <Evaluation Method and Criteria> [Composition and Film Thickness of Each Layer] The chemical composition of the absorber film was measured using an ULVAC-PHI X-ray photoelectron spectrometer (PHI 5000 VersaProbe) by the above-mentioned XPS or RBS. The film thickness of each layer was measured by the above-mentioned XRR.

[0071] [Optical Constants] The refractive index n and extinction coefficient k were calculated using the method described above.

[0072] [SPM Resistance] A reflective mask blank was immersed in SPM (sulfuric acid peroxide solution) at 100°C for 20 minutes. The change in film thickness of the absorber film before and after immersion was measured by XRR, and the etching rate of the absorber film by SPM (unit: nm / min) was measured by dividing the result by the immersion time. From the obtained etching rate, the SPM resistance of the absorber film was evaluated according to the following evaluation criteria. In practical terms, an evaluation of B or higher is preferable. SPM was obtained by mixing concentrated sulfuric acid and hydrogen peroxide solution in a ratio of 75 vol%:25 vol% (concentrated sulfuric acid:hydrogen peroxide solution). The concentrated sulfuric acid contained 96 vol% sulfuric acid and 4 vol% water. The hydrogen peroxide solution contained 30-35 vol% hydrogen peroxide and 65-70 vol% water. "A": Etching rate less than 0.025 nm / min "B": Etching rate 0.025 nm / min or more, less than 0.05 nm / min "C": Etching rate 0.05 nm / min or more

[0073] <Results> The composition of the absorber membrane of each reflective mask blank and the evaluation results are shown in Table 1 below.

[0074]

[0075] The results shown in Table 1 confirm that when an absorber film containing Pd and element X in a predetermined ratio is used, the refractive index n for EUV light is small, the extinction coefficient k for EUV light is large, and the SPM resistance is excellent (Examples 1-14).

[0076] It was confirmed that SPM resistance is superior when the Pd content in the absorber membrane is 60 atomic% or less relative to the total atoms of the absorber membrane (Examples 1-4, 6-9, 11-13). It was confirmed that SPM resistance is superior when the Ru content in the absorber membrane is 40 atomic% or more relative to the total atoms of the absorber membrane, and the extinction coefficient k is larger when it is 70 atomic% or less (Examples 2-4). It was confirmed that SPM resistance is superior when the Ir content in the absorber membrane is 40 atomic% or more relative to the total atoms of the absorber membrane, and the refractive index n is smaller when it is 80 atomic% or less (Examples 8, 9). It was confirmed that SPM resistance is superior when the Pt content in the absorber membrane is 40 atomic% or more relative to the total atoms of the absorber membrane (Examples 11-13).

[0077] 10 Reflective mask blank 12 Substrate 14 Multilayer reflective film 16 Protective film 18 Absorber film 18pt Absorber film pattern 40, 41 Resist pattern

[0078] Furthermore, the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2025-004095, filed on January 10, 2025, 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, and an absorber film, wherein the absorber film contains palladium and at least one element X selected from the group consisting of ruthenium, iridium, and platinum, the total content of palladium and element X in the absorber film is 80 atomic percent or more relative to the total metal atoms contained in the absorber film, if element X is only ruthenium, the content of element X in the absorber film is 20 atomic percent or more and 75 atomic percent or less relative to the total atoms of the absorber film, and if element X includes at least one of iridium and platinum, the content of element X in the absorber film is 30 atomic percent or more relative to the total atoms of the absorber film.

2. The reflective mask blank according to claim 1, wherein the extinction coefficient of the absorber film at a wavelength of 13.5 nm is 0.023 or greater.

3. The reflective mask blank according to claim 2, wherein the extinction coefficient of the absorber film at a wavelength of 13.5 nm is 0.025 or greater.

4. The reflective mask blank according to claim 1, wherein the refractive index of the absorber film at a wavelength of 13.5 nm is 0.910 or less.

5. The reflective mask blank according to claim 1, wherein the refractive index of the absorber film at a wavelength of 13.5 nm is 0.900 or less.

6. The reflective mask blank according to claim 1, wherein the palladium content in the absorber membrane is 25 atomic percent or more and 60 atomic percent or less relative to the total atoms of the absorber membrane, and the ruthenium content in the absorber membrane is 40 atomic percent or more and 75 atomic percent or less relative to the total atoms of the absorber membrane.

7. The reflective mask blank according to claim 1, wherein the palladium content in the absorber membrane is 5 atomic percent or more and 70 atomic percent or less relative to the total atoms of the absorber membrane, and the iridium content in the absorber membrane is 30 atomic percent or more and 95 atomic percent or less relative to the total atoms of the absorber membrane.

8. The reflective mask blank according to claim 1, wherein the palladium content in the absorber membrane is 5 atomic percent or more and 70 atomic percent or less relative to the total atoms of the absorber membrane, and the platinum content in the absorber membrane is 30 atomic percent or more and 95 atomic percent or less relative to the total atoms of the absorber membrane.

9. The reflective mask blank according to any one of claims 1 to 8, wherein the palladium content in the absorber membrane is 60 atomic percent or less relative to the total atoms of the absorber membrane.

10. The reflective mask blank according to any one of claims 1 to 8, wherein the absorbent membrane contains at least one element selected from the group consisting of nitrogen, boron, oxygen, and carbon.

11. A reflective mask blank according to any one of claims 1 to 8, further comprising a protective film between the absorber film and the multilayer reflective film, wherein the protective film contains rhodium.

12. A reflective mask having an absorbent film pattern formed by patterning the absorbent film of a reflective mask blank according to any one of claims 1 to 8.

13. A method for manufacturing a reflective mask, comprising the step of patterning the absorbent membrane of a reflective mask blank according to any one of claims 1 to 8.

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