Reflection mask blank, reflection mask, and method for producing reflection mask

Abstract

The present invention addresses the problem of providing a reflective mask blank in which after an absorber film is etched, an altered layer is less likely to form on the side surface of the absorber film that was exposed by etching. This reflective mask blank (10) has, in the following order a substrate (12), a multilayer reflective film (14) that reflects EUV light, an absorber film (18) that includes two or more metal elements, and an etching mask film (20) that includes one or more metal elements. The reflective mask blank (10) satisfies the relationship of formula (1) relating to the oxide standard formation Gibbs energy of the metal elements included in the absorber film (18) and the oxide standard generation Gibbs energy of the metal elements included in the etching mask film (20).

Description

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

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

[0002] In recent years, in order to further miniaturize semiconductor devices, EUV lithography using EUV light with a central wavelength of around 13.5 nm as a light source has been considered.

[0003] Due to the characteristics of EUV light, EUV exposure uses a reflective optical system and a reflective mask. A reflective mask has a multilayer reflective film that reflects EUV light formed on a 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 an illumination optical system of an exposure tool is reflected by areas without an absorber film (openings) and absorbed by areas with an absorber film (non-openings). As a result, the mask pattern is transferred as a resist pattern onto a wafer through a reduced projection optical system of the exposure tool, and subsequent processing is performed. For example, Patent Document 1 discloses a material used for the absorber film, which contains tantalum (Ta) and an element selected from the group consisting of cobalt (Co) and nickel (Ni).

[0005] Japanese Patent Application Laid-Open No. 2020-034666

[0006] When fabricating a reflective mask, the absorber film of a reflective mask blank is patterned. The absorber film is patterned, for example, by dry etching using an etching mask film pattern created by processing an etching mask film provided on the absorber film as a mask. By the dry etching, the absorber film is etched at the openings of the etching mask film pattern, and the absorber film is patterned into a shape corresponding to the pattern of the etching mask film used. When the present inventors investigated the patterning of an absorber film containing, for example, Ta, as in the embodiment described in the above patent document, they found that an altered layer sometimes occurred on the sidewall of the absorber film pattern. In order to process the absorber film into a desired pattern shape, it is preferable to suppress the occurrence of the altered layer.

[0007] The present invention has been made in view of the above-mentioned problems, and aims to provide a reflective mask blank in which, after etching the absorber film, an altered layer is unlikely to occur on the side surfaces of the absorber film exposed by etching. Another aim of the present invention is to provide a reflective mask and a method for manufacturing a reflective mask.

[0008] As a result of extensive research into the above-mentioned problems, the inventors discovered that the generation of an altered layer can be suppressed by adjusting the standard Gibbs energy of formation of oxides of metal elements contained in an absorber film and an etching mask film, and arrived at the present invention. That is, the inventors found that the above-mentioned problems 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, an absorber film containing two or more metal elements, and an etching mask film containing one or more metal elements, which satisfies the relationship of the following formula (1). Formula (1) G ＡＢＳ -G ＨＭ ≧ 100 kJ / mol In formula (1), G ＡＢＳ and G ＨＭ The unit is kJ / mol. ＡＢＳis a value obtained by multiplying the standard Gibbs energy of formation of an oxide of each metal element in the metal element group MA by the atomic ratio of the content of each metal element in the metal element group MA to the total content of the metal element group MA, when the metal elements contained in the absorber film are defined as a metal element group MA. ＨＭis the value of the standard Gibbs energy of formation of an oxide of a metal element in the metal element group MH when the metal element group MH contains only one metal element, and is the sum of calculated values ​​obtained by multiplying the standard Gibbs energy of formation of an oxide of each metal element in the metal element group MH by the atomic ratio of the content of each metal element in the metal element group MH to the total content of the metal element group MH when the metal element group MH contains only one metal element. [2] The reflective mask blank according to [1], wherein the metal element group MA contains at least one metal element selected from the group consisting of ruthenium, palladium, iridium, platinum, silver, nickel, and cobalt. [3] The reflective mask blank according to [1] or [2], wherein the metal element group MH contains at least one metal element selected from the group consisting of ruthenium, rhodium, aluminum, chromium, silicon, tantalum, titanium, hafnium, and yttrium. [4] The reflective mask blank according to any one of [1] to [3], wherein the group of metal elements MA comprises ruthenium and at least one metal element selected from the group consisting of chromium, tungsten, niobium, and tantalum. [5] The reflective mask blank according to any one of [1] to [4], wherein the group of metal elements MA comprises iridium and at least one metal element selected from the group consisting of chromium, ruthenium, tungsten, niobium, and tantalum. [6] The reflective mask blank according to any one of [1] to [5], wherein the group of metal elements MA comprises platinum and at least one metal element selected from the group consisting of chromium, ruthenium, tungsten, niobium, and tantalum. [7] The reflective mask blank according to any one of [1] to [6], wherein the group of metal elements MA comprises platinum and ruthenium. [8] The reflective mask blank according to any one of [1] to [7], wherein the group of metal elements MA includes at least one metal element selected from the group consisting of nickel and cobalt.[9] The reflective mask blank according to any one of [1] to [8], wherein the absorber film further contains at least one element selected from the group consisting of boron, carbon, nitrogen, and oxygen.

[10] The reflective mask blank according to any one of [1] to [9], wherein the metal element group MH contains at least one metal element selected from the group consisting of ruthenium, aluminum, chromium, and tantalum.

[11] The reflective mask blank according to any one of [1] to

[10] , wherein the etching mask film further contains at least one element selected from the group consisting of boron, carbon, nitrogen, and oxygen.

[12] The reflective mask blank according to any one of [1] to

[11] , further comprising a protective film between the absorber film and the multilayer reflective film, wherein the protective film contains 50 atomic % or more of rhodium relative to all atoms of the protective film.

[13] The reflective mask blank according to any one of [1] to

[12] , which satisfies the relationship of the following formula (2): Formula (2) G. ＡＢＳ -G ＨＭ ≧ 150 kJ / mol In formula (2), G ＡＢＳ and G ＨＭ The unit is kJ / mol.

[14] 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

[13] .

[15] A method for manufacturing a reflective mask, comprising a step of patterning the absorber film of the reflective mask blank according to any one of [1] to

[13] .

[0009] According to the present invention, it is possible to provide a reflective mask blank in which, after etching the absorber film, an altered layer is unlikely to occur on the side surface of the absorber film exposed by etching. Furthermore, according to the present invention, it is also possible to provide a reflective mask and a method for manufacturing a reflective mask.

[0010] 1A to 1C are cross-sectional views showing an example of an embodiment of the reflective mask blank of the present invention, and FIG. 1B are cross-sectional views showing an example of a manufacturing process of a reflective mask using the reflective mask blank of the present invention.

[0011] The present invention will be described in detail below. The following description of the components may be based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0012] The meaning of each description in this specification is shown below. In this specification, a numerical range expressed using "to" means a range including the numerical values ​​before and after "to" 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, and platinum may be represented by their corresponding element symbols (B, C, N, O, Si, Ti, Cr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Hf, Ta, W, Re, Os, Ir, and Pt, etc.). In addition, in this specification, silicon (Si) is included in the metal elements.

[0013] In this specification, the standard Gibbs energy of formation of an oxide of a metal element refers to the standard free energy required to combine oxygen and a metal element from a simple metal element under standard conditions (298.15 K (25°C), 1 atmosphere (101325 Pa)) to produce a metal oxide containing 1 mol of the metal element. For example, Cr ２ O ３ Since the composition formula contains two Cr atoms, Cr oxide (Cr ２ O ３ The standard Gibbs energy of formation of Cr ２ O ３ The standard Gibbs energy of formation of Cr oxide in this specification is determined by dividing the standard Gibbs energy of formation of Cr oxide by 2. Unless otherwise specified, the oxide of a metal element refers to the oxide of a metal element that is most stable under standard conditions.

[0014] In this specification, the standard Gibbs energies of formation of oxides of metal elements refer to the values ​​described in "Chemical Handbook," 4th Revised Edition, Basics II, compiled by the Chemical Society of Japan, Maruzen Co., Ltd., September 30, 1993, pp. 285-294. For the standard Gibbs energies of formation of oxides of metal elements not described in the above literature, literature values ​​can be used. For example, in this specification, the standard Gibbs energies of formation of oxides of the following metal elements refer to the following values ​​obtained by referring to the following respective literatures: Ru: -253 kJ / mol (see JP 2024-038390 A, paragraphs 0037 to 0040) Ir: -193 kJ / mol (see JP 2024-038390 A, paragraphs 0037 to 0040) Pt: -81 kJ / mol (see JP 2023-141692 A, paragraph 0072)

[0015] <Reflective Mask Blank> The reflective mask blank of the present invention has a substrate, a multilayer reflective film that reflects EUV light, an absorber film, and an etching mask film, in this order. The absorber film contains two or more metal elements, and the etching mask film contains one or more metal elements. Here, the reflective mask blank of the present invention satisfies the relationship of the following formula (1). Formula (1) G ＡＢＳ -G ＨＭ ≧ 100 In formula (1), G ＡＢＳ and G ＨＭ The unit is kJ / mol. ＡＢＳ is a value obtained by multiplying the standard Gibbs energy of formation of an oxide of each metal element in the metal element group MA by the atomic ratio of the content of each metal element in the metal element group MA in the absorber film to the total content of the metal element group MA in the absorber film, when the group consisting of all metal elements contained in the absorber film is defined as the metal element group MA. ＨＭ When the metal element group MH is a group consisting of all the metal elements contained in the etching mask film, and the metal element group MH consists of only one metal element, G is the value of the standard Gibbs energy of formation of an oxide of the metal element in the metal element group MH. On the other hand, when the metal element group MH consists of two or more metal elements, G ＨＭis a value obtained by summing up calculated values ​​obtained by multiplying the standard Gibbs energy of formation of an oxide of each metal element in the metal element group MH by the atomic ratio of the content of each metal element in the metal element group MH in the etching mask film to the total content of the metal element group MH in the etching mask film. ＡＢＳ and G ＨＭ An example of a method for calculating the reflective mask blank of the present invention will be described in detail later. The reflective mask blank of the present invention will be described with reference to the drawings.

[0016] FIG. 1 is a cross-sectional view showing one 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, an absorber film 18, and an etching mask film 20, in this order. The absorber film 18 contains a metal element group MA consisting of two or more metal elements, and the etching mask film 20 contains a metal element group MH consisting of one or more metal elements. The reflective mask blank 10 shown in FIG. 1 may also have a conductive film, described below, on the side of the substrate 12 opposite to the multilayer reflective film 14 side. Furthermore, although the reflective mask blank 10 shown in FIG. 1 has a protective film 16, the protective film 16 may be omitted.

[0017] In the reflective mask blank of the present invention, the mechanism by which an altered layer is unlikely to occur on the side surface of the absorber film exposed by etching after etching the absorber film is not entirely clear, but the inventors speculate as follows. When etching the absorber film, dry etching is often performed using an etching mask film pattern as a mask. When dry etching the absorber film, processing is usually performed using a combination of the chemical action of an etchant and the physical action of ion collisions. The reflective mask blank of the present invention satisfies the relationship of the above-mentioned formula (1). G in formula (1) ＡＢＳ and the value of G ＨＭThe values ​​of Λ and Λ represent the degree of oxidation susceptibility of the absorber film and the etching mask film, respectively. When the above formula (1) is satisfied, it can be said that the etching mask film is more easily oxidized (more reactive) than the absorber film. After the absorber film is etched, the side surfaces of the absorber film may be subjected to chemical attack by the etchant. Here, when the above formula (1) is satisfied, the etching mask film is more easily oxidized (more reactive) and is preferentially oxidized (reacted), so it is thought that the side surfaces of the absorber film are less likely to be altered. As a result, in the reflective mask blank of the present invention, it is thought that after the absorber film is etched, an altered layer is less likely to be formed on the side surfaces of the absorber film exposed by etching.

[0018] The configuration of the reflective mask blank of the present invention will be described below. Hereinafter, the fact that an altered layer is unlikely to occur on the side surface of the absorber film exposed by etching after the absorber film has been etched will also be referred to simply as "an altered layer is unlikely to occur on the side surface of the absorber film." In this specification, the term "altered layer" refers to a layer whose composition is different from that of the unprocessed portion of the absorber film. The method described in the examples below can be used to confirm whether an altered layer has occurred on the side surface of the absorber film. For example, when an oxygen-containing gas is used in the etching process, an altered layer with a higher oxygen content than the unprocessed portion of the absorber film is often formed.

[0019] [Substrate] The substrate of the reflective mask blank of the present invention preferably has a small thermal expansion coefficient. A substrate with a small thermal expansion coefficient can suppress distortion of the absorber film pattern due to heat during exposure to EUV light. The thermal expansion coefficient of the substrate is 0±1.0×10 at 20° C. －７ / °C, and 0±0.3×10 －７ / °C is more preferable. Examples of materials with a small thermal expansion coefficient include SiO ２ -TiO ２ However, the present invention is not limited to this, and substrates made of crystallized glass in which β-quartz solid solution is precipitated, quartz glass, metallic silicon, metal, and the like can also be used. ２ -TiO２ The SiO-based glass ２ 90 to 95 mass% of TiO ２ It is preferable to use quartz glass containing 5 to 10 mass % of TiO ２ When the content of SiO is 5 to 10 mass %, the linear expansion coefficient is approximately zero at around room temperature, and there is almost no change in dimension at around room temperature. ２ -TiO ２ The SiO-based glass ２ and TiO ２ It may contain other minor components.

[0020] The surface of the substrate on which the multilayer reflective film is laminated (hereinafter also referred to as the "first principal surface") preferably has high surface smoothness. The surface smoothness of the first principal surface can be evaluated by surface roughness. The surface roughness of the first principal surface is preferably 0.15 nm or less in terms of root-mean-square roughness Rq. Note that the surface roughness can be measured using an atomic force microscope, and the surface roughness is described as the root-mean-square roughness Rq based on JIS-B0601. The first principal surface is preferably surface-processed to achieve a predetermined flatness, in order to improve the pattern transfer accuracy and positional accuracy of a reflective mask obtained using the reflective mask blank. In a predetermined region of the first principal surface (e.g., a 132 mm × 132 mm region), the flatness of the substrate 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 using a flatness measuring instrument manufactured by Fujinon Corporation. The size and thickness of the substrate are determined appropriately based on the design values ​​of the mask, etc. For example, the outer shape may be 6 inches (152 mm) square and the thickness may be 0.25 inches (6.3 mm). The substrate is often rectangular (oblong) or square. Furthermore, it is preferable that the substrate has high rigidity in order to prevent deformation due to film stress of films (multilayer reflective films, absorber films, etc.) formed on the substrate. For example, it is preferable that the Young's modulus of the substrate is 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 for 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 for EUV light with a wavelength of around 13.5 nm is preferably 60% or more, more preferably 65% ​​or more. Similarly, even when a protective film is laminated on the multilayer reflective film, the maximum reflectivity for EUV light with a wavelength of around 13.5 nm is preferably 60% or more, more preferably 65% ​​or more.

[0022] Since multilayer reflective films can achieve high reflectivity for EUV light, they are typically formed by alternately stacking multiple high-refractive index layers, which exhibit a high refractive index for EUV light, and multiple low-refractive index layers, which exhibit a low refractive index for EUV light. The multilayer reflective film may be formed by stacking multiple cycles of a stack structure in which high-refractive index layers and low-refractive index layers are stacked in this order from the substrate side, or multiple cycles of a stack structure in which low-refractive index layers and high-refractive index layers are stacked in this order. The high-refractive index layer may be a layer containing Si. Examples of materials containing Si include elemental Si and Si compounds containing one or more elements selected from the group consisting of B, C, N, and O. The use of a high-refractive index layer containing Si results in a reflective mask with excellent reflectivity for EUV light. The low-refractive index layer may be a layer containing a metal selected from the group consisting of Mo, Ru, Rh, and Pt, or an alloy thereof. Si is commonly used for the high-refractive index layer, and Mo is commonly used for the low-refractive index layer. That is, Mo / Si multilayer reflective films are most common, but the multilayer reflective films are 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.

[0023] The thickness of each layer constituting the multilayer reflective film and the number of layer repeat units can be appropriately selected depending on the film material used and the reflectivity of EUV light required for the reflective layer. Taking a Mo / Si multilayer reflective film as an example, to obtain a multilayer reflective film with a maximum reflectivity of 60% or more for EUV light, Mo films with a thickness of 2.3±0.1 nm and Si films with a thickness of 4.5±0.1 nm can be stacked so that the number of repeat units is 30 to 60. The multilayer reflective film preferably has a reflectivity of 60% or more for EUV light at an incident angle θ of 6°. More preferably, the reflectivity 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 of a high refractive index material and a target of a low refractive index material. When the multilayer reflective film is a Mo / Si multilayer reflective film, for example, a Si layer of a predetermined thickness is first deposited on a substrate using an ion beam sputtering method. Then, a Mo layer of a predetermined thickness is deposited using an Mo target. This Si layer and Mo layer constitute one cycle, and for example, 30 to 60 cycles (preferably 40 to 50 cycles) are stacked to form a Mo / Si multilayer reflective film.

[0025] [Protective Film] The reflective mask blank of the present invention may have a protective film between the reflective multilayer film and the absorber film. The protective film is provided for the purpose of protecting the reflective multilayer film from damage during an etching process (usually a dry etching process) to form a pattern on the absorber film. It is also preferable that the protective film also serves to protect the reflective multilayer film during removal of the etching mask film.

[0026] Examples of materials that can achieve the above objective include materials containing at least one element selected from the group consisting of Si, Ru, and Rh. That is, the protective film preferably contains at least one element selected from the group consisting of Si, Ru, and Rh. Furthermore, the protective film preferably contains Rh. When the protective film contains Rh, it is also preferable that the Rh content be 50 atomic % or more of the total atoms in the protective film. More specifically, examples of the materials include Ru metal alone, 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, and Rh metal alone, 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 reduce the extinction coefficient while suppressing an increase in the refractive index, and can easily improve the reflectance to EUV light. Also, adding Ta, Ir, Pd, or Y to Rh can easily improve the resistance to the etching process. Furthermore, materials that can achieve the above object include Al and nitrides containing these metals and nitrogen, and Al ２ O ３ Among these, metal Ru alone, a Ru alloy, metal Rh alone, or a Rh alloy is preferred as a material that can achieve the above-mentioned object.

[0027] When the protective film contains Ru or Rh, the protective film may contain at least one element selected from the group consisting of B, C, N, and O.

[0028] The thickness of the protective film is not particularly limited as long as it can function as a protective film. From the viewpoint of maintaining the reflectivity 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, from the viewpoint of obtaining good 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. It is also preferable that the material of the protective film is Ru metal alone, a Ru alloy, Rh metal alone, or a Rh alloy, and the thickness of the protective film is within the above-mentioned preferred thickness range. The thickness of the protective film is determined by X-ray reflectivity (XRR).

[0029] The protective film may be a film consisting of a single layer, or may be a multilayer film consisting of multiple layers. When the protective film is a multilayer film, each layer constituting the multilayer film is preferably made of the above-mentioned preferred material. Furthermore, when the protective film is a multilayer film, it is also preferable that the total thickness of the multilayer film is within the above-mentioned preferred range. When the protective film is a multilayer film, it is preferable that the layer of the multilayer film arranged closest to the absorber film contains Rh. Furthermore, when the layer of the multilayer film arranged closest to the absorber film contains Rh, it is preferable that at least one of the other layers contains Ru.

[0030] The protective film can be formed by a known film formation method such as DC sputtering, magnetron sputtering, ion beam sputtering, etc. When forming a Rh film by magnetron sputtering, it is preferable to use a Rh target as the target and Ar gas as the sputtering gas.

[0031] [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 at 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 as a phase shift mask that reflects EUV light and interferes with the EUV light from the multilayer reflective film to generate contrast. The absorber film pattern may be used as a binary mask, as described below, or as a phase shift mask, as described below. That is, the absorber film may be a phase shift film. The absorber film contains two or more metal elements. That is, the metal element group MA, which is a group consisting of all metal elements contained in the absorber film, contains two or more metal elements.

[0032] The number of types of metal elements contained in the absorber film (the number of metal elements contained in the metal element group MA) may be three or more. The number of types of metal elements contained in the absorber film (the number of metal elements contained in the metal element group MA) is often five or less, and preferably four or less.

[0033] The reflective mask blank of the present invention satisfies the relationship of the above-mentioned formula (1) and has a G ＡＢＳ The calculation method for is as described above. ＡＢＳ is a metal element M １ , metallic element M ２ ,..., metallic element M ｎ (n is a positive integer of 2 or more), it is calculated by the following formula (a).

[0034]

[0035] In formula (a), G ｉ is the metal element M ｉ is the standard Gibbs energy of formation of the oxide of ｉ is the ratio of the metal element M to the total content of the metal element group MA ｉ is the atomic ratio of the content of

[0036] Hereinafter, as an example, when the absorber film contains Ru and W as the metal element group MA, and the ratio of the content of Ru in the absorber film to the total content of Ru and W in the absorber film is 51 atomic %, ＡＢＳ First, the calculation of Ru oxide (RuO ２ ) standard Gibbs energy of formation G Ｒｕ Next, the calculated value is calculated by multiplying the W oxide (WO ３ ) standard Gibbs energy of formation G Ｗ The above two calculated values ​​are summed up to obtain the value G ＡＢＳ That is, G ＡＢＳ is 0.51 x G Ｒｕ +0.49 x G Ｗ It is calculated as follows.

[0037] G calculated by the above procedure ＡＢＳ The value of is often -900 kJ / mol or more, preferably -800 kJ / mol or more, more preferably -700 kJ / mol or more, and even more preferably -600 kJ / mol or more. ＡＢＳ The value is often 0 kJ / mol or less.

[0038] The metal element group MA preferably contains at least one metal element selected from the group consisting of Ru, Pd, Ir, Pt, Ag, Ni, and Co (hereinafter also referred to as "specific metal element MX"). The total content of the specific metal element MX in the absorber film is not particularly limited as long as the above formula (1) is satisfied, but is preferably 5 atomic % or more, more preferably 8 atomic % or more, or may be 12 atomic % or more, 15 atomic % or more, or may be 20 atomic % or more, relative to the total content of the metal element group MA in the absorber film. Furthermore, the total content of the specific metal element MX in the absorber film is not particularly limited as long as the above formula (1) is satisfied, but may be 100 atomic %, preferably 95 atomic % or less, more preferably 90 atomic % or less, and even more preferably 86 atomic % or less, relative to the total content of the metal element group MA in the absorber film. The specific metal element MX is preferably at least one metal element selected from the group consisting of Ru, Ir, and Pt.

[0039] The metal element group MA may contain an element other than the specific metal element MX. Examples of the element in the metal element group MA other than the specific metal element MX include at least one element selected from the group consisting of Al, Cr, Mo, Nb, Si, Sn, Ta, Ti, W, Zr, and V, and at least one element selected from the group consisting of Cr, W, Nb, and Ta is preferred.

[0040] Furthermore, it is also preferable that the metal element group MA contains Ru and at least one metal element selected from the group consisting of Cr, W, Nb, and Ta. That is, when Ru is contained as the specific metal element MX, it is preferable that the metal element group MA contains at least one metal element selected from the group consisting of Cr, W, Nb, and Ta. When Ru is contained as the specific metal element MX, the content of Ru in the absorber film is not particularly limited as long as the above formula (1) is satisfied, but it is preferably 10 atomic % or more, more preferably 15 atomic % or more, even more preferably 20 atomic % or more, particularly preferably 40 atomic % or more, and most preferably 45 atomic % or more, relative to the total content of the metal element group MA in the absorber film. Furthermore, it is not particularly limited as long as the above formula (1) is satisfied, but it is preferably 95 atomic % or less, more preferably 90 atomic % or less, even more preferably 85 atomic % or less, particularly preferably 70 atomic % or less, and most preferably 65 atomic % or less, relative to the total content of the metal element group MA in the absorber film. Furthermore, when the specific metal element MX includes Ru, the metal element group MA more preferably includes at least one metal element selected from the group consisting of Cr and W.

[0041] It is also preferable that the metal element group MA contains Ir and at least one metal element selected from the group consisting of Cr, Ru, W, Nb, and Ta. That is, when Ir is contained as the specific metal element MX, it is also preferable that the metal element group MA contains at least one metal element selected from the group consisting of Cr, W, and Ta. When Ir is contained as the specific metal element MX, the content of Ir in the absorber film is not particularly limited as long as the above formula (1) is satisfied, but it is preferably 5 atomic % or more, more preferably 8 atomic % or more, even more preferably 15 atomic % or more, particularly preferably 30 atomic % or more, and most preferably 45 atomic % or more, relative to the total content of the metal element group MA in the absorber film. Furthermore, the content of Ir in the absorber film is not particularly limited as long as the above formula (1) is satisfied, but it is preferably 90 atomic % or less, more preferably 85 atomic % or less, even more preferably 80 atomic % or less, and particularly preferably 70 atomic % or less, relative to the total content of the metal element group MA in the absorber film. When Ir is included as the specific metal element MX, the metal element group MA preferably includes at least one metal element selected from the group consisting of Cr and W.

[0042] It is also preferable that the metal element group MA contains Pt and at least one metal element selected from the group consisting of Cr, Ru, W, Nb, and Ta. That is, when the specific metal element MX contains Pt, it is also preferable that it contains at least one metal element selected from the group consisting of Cr, Ru, W, Nb, and Ta. It is also preferable that the specific metal element MA contains Pt and Ru. When the specific metal element MX contains Pt, the content of Pt in the absorber film is not particularly limited as long as the relationship of the above formula (1) is satisfied, but it is preferably 5 atomic % or more, more preferably 10 atomic % or more, even more preferably 12 atomic % or more, particularly preferably 20 atomic % or more, and most preferably 50 atomic % or more, relative to the total content of the metal element group MA in the absorber film. Furthermore, the content of Pt in the absorber film is not particularly limited as long as the relationship of the above formula (1) is satisfied, but it 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, relative to the total content of the metal element group MA in the absorber film. When Pt is included as the specific metal element MX, the metal element group MA preferably includes at least one metal element selected from the group consisting of Cr, Ru, and W, and more preferably includes at least one metal element selected from the group consisting of Cr and Ru.

[0043] It is also preferable that the metal element MA contains at least one metal element selected from the group consisting of Ni and Co.

[0044] The absorber film may further contain an element other than the metal element group MA. Examples of the element other than the metal element group MA include at least one element selected from the group consisting of B, C, N, and O. It is also preferable that the absorber film does not contain any element other than the metal element group MA.

[0045] The total content of the metal element group MA in the absorber film is preferably 30 atomic % or more, more preferably 50 atomic % or more, and even more preferably 60 atomic % or more, based on all atoms in the absorber film. The total content of the metal element group MA in the absorber film may be 100 atomic % based on all atoms in the absorber film. That is, the absorber film may consist only of the metal element group MA.

[0046] The type and content of elements contained in the absorber film are obtained by X-ray photoelectron spectroscopy (XPS). When measuring the type and content of elements contained in the absorber film by XPS, the layer present on the side opposite to the substrate side of the absorber film is removed by sputtering or the like before the measurement is performed. The detailed measurement method is described below.

[0047] For XPS analysis, an analytical instrument "PHI 5000 VersaProbe" manufactured by ULVAC-PHI, Inc. was used. The instrument was calibrated in accordance with JIS K 0145. First, a measurement sample approximately 1 cm square was cut out from a reflective mask blank. The obtained measurement sample was placed in a measurement holder so that the etching mask film side was the measurement surface. After the measurement holder was loaded into the instrument, the etching mask film was removed from the outermost surface of the etching mask film by a thickness equal to half the thickness of the absorber film. The sputtering rate during this removal can be measured using a separately prepared sample. After removing a portion of the absorber film, the removed portion was irradiated with X-rays (monochromated AlKα rays), and analysis was performed with a photoelectron take-off angle (the angle between the surface of the measurement sample and the direction of the detector) of 45°. During analysis, a neutralization gun was used to suppress charge buildup. The analysis involves performing a wide scan in the binding energy range of 1000 to 0 eV to confirm the elements present, followed by a narrow scan depending on the elements present (e.g., Ru and W). 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 five 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 two integrations. The content of each element in the absorber film is analyzed using the relative sensitivity coefficients specific to each element and each orbital from the spectrum obtained by narrow scanning when XPS analysis is performed using the above procedure. Note that analysis may also be performed using a model sample formed under the same conditions as those for forming the absorber film, following the same procedure as above.

[0048] When the absorber film pattern is used as a binary mask, it is preferable that the absorber film absorbs EUV light and has low reflectance for EUV light. Specifically, when EUV light is irradiated onto the surface of the absorber film, the maximum reflectance for EUV light at a wavelength of around 13.5 nm is preferably 2% or less. When the absorber film pattern is used as a binary mask, the film thickness of the absorber film is preferably 40 to 70 nm, more preferably 50 to 65 nm. The film thickness of the absorber film is determined by XRR.

[0049] When the absorber film pattern is used as a phase shift mask, the reflectance of the absorber film to EUV light is preferably 2% or more. In order to obtain a sufficient phase shift effect, the reflectance of the absorber film is preferably 9 to 15%. When the absorber film is used as a phase shift mask, the contrast of the optical image on the wafer is improved and the exposure margin is increased. When the absorber film pattern is used as a phase shift mask, the film thickness of the absorber film is preferably 30 to 75 nm, more preferably 35 to 55 nm. The film thickness of the absorber film is determined by XRR.

[0050] The refractive index n of the absorber film is preferably 0.885 or more. When the absorber film is used as a phase shift film, the refractive index n of the absorber film is preferably 0.93 or less, more preferably 0.920 or less, and even more preferably 0.910 or less, in order to make the thickness of the absorber film thinner. The extinction coefficient k of the absorber film is preferably 0.050 or less, more preferably 0.040 or less, and even more preferably 0.035 or less. The extinction coefficient k of the absorber film is preferably 0.018 or more, more preferably 0.020 or more, and even more preferably 0.022 or more, in order to make it easier to adjust the reflectance of the absorber film. The refractive index n and extinction coefficient k are determined by measuring the incidence angle dependence of the reflectance using EUV light with a wavelength of 13.5 nm, and fitting the obtained profile using the refractive index n and extinction coefficient k as parameters.

[0051] The crystalline state of the absorber film may be amorphous. When the crystalline state of the absorber film is amorphous, the smoothness and flatness of the absorber film can be further improved. Furthermore, when the smoothness and flatness of the absorber film are improved, the edge roughness of the absorber film pattern is reduced, and the dimensional accuracy of the absorber film pattern can be improved.

[0052] The absorber film may be a single-layer film or a multilayer film made up of multiple films. When the absorber film is a single-layer film, the number of steps in manufacturing the mask blank can be reduced, thereby improving production efficiency. When the absorber film is a multilayer film, the layer disposed on the opposite side of the absorber film from the protective film side may be an anti-reflection film used when inspecting the absorber film pattern using inspection light (for example, wavelength 193 to 248 nm).

[0053] The absorber film can be formed using known film formation methods such as DC sputtering, magnetron sputtering, and ion beam sputtering. For example, when forming a RuW film as the absorber film using magnetron sputtering, the absorber film can be formed by using a Ru target and a W target and supplying Ar gas to perform sputtering. Furthermore, when forming a RuW film, a target containing Ru and W may be used.

[0054] [Etching Mask Film] The reflective mask blank of the present invention has an etching mask film on the side opposite the substrate side of the absorber film. Forming an etching mask film on the absorber film eliminates the need to use a resist pattern as a mask, making dry etching easy to perform even if the minimum line width of the absorber film pattern is small. Furthermore, the film thickness of the resist pattern can be reduced. Therefore, this is effective for miniaturizing the absorber film pattern. The etching mask film contains one or more metal elements. That is, the metal element group MH, which is a group consisting of all metal elements contained in the etching mask film, contains one or more metal elements.

[0055] The number of types of metal elements contained in the etching mask film (the number of metal elements contained in the metal element group MH) may be two or more, or may be three or more. The number of types of metal elements contained in the etching mask film (the number of metal elements contained in the metal element group MH) is often five or less, and preferably four or less.

[0056] The reflective mask blank of the present invention satisfies the relationship of the above-mentioned formula (1) and has a G ＨＭ The calculation method for is as described above. ＨＭ The etching mask film is a metal element group MH, and the metal element M １ , metallic element M ２ ,..., metallic element M ｍ (m is a positive integer of 1 or more), it is calculated by the following formula (h).

[0057]

[0058] In formula (h), G ｊ is the metal element M ｊ is the standard Gibbs energy of formation of the oxide of ｊ is the ratio of the metal element M to the total content of the metal element group MH ｊ is the atomic ratio of the content of

[0059] As an example, the etching mask film contains only Ta as the metal element group MH. ＨＭ In the above case, G ＨＭ is Ta oxide (Ta ２ O ５ ) standard Gibbs energy of formation G Ｔａ In addition, when the metal element group MH includes two or more metal elements, G ＨＭ The calculation method is the same as above. ＡＢＳ The calculation method is the same as above.

[0060] G calculated by the above procedure ＨＭ The value of G is often -1500 kJ / mol or more, preferably -1200 kJ / mol or more, and may be -1000 kJ / mol or more. ＨＭThe value is often 0 kJ / mol or less, preferably −100 kJ / mol or less, more preferably −300 kJ / mol or less, and even more preferably −500 kJ / mol or less.

[0061] The metal element group MH preferably contains at least one metal element selected from the group consisting of Ru, Rh, Al, Cr, Si, Ta, Ti, Hf, and Y, and more preferably contains at least one metal element selected from the group consisting of Ru, Al, Cr, and Ta.

[0062] The etching mask film may further contain an element other than the metal element group MH. Examples of the element other than the metal element group MH include at least one element selected from the group consisting of B, C, N, and O. It is also preferable that the etching mask film does not contain any element other than the metal element group MH.

[0063] The total content of the metal element group MH in the etching mask film is preferably 30 atomic % or more, more preferably 50 atomic % or more, and even more preferably 60 atomic % or more, based on all atoms in the etching mask film. The total content of the metal element group MH in the etching mask film may be 100 atomic % based on all atoms in the etching mask film. That is, the etching mask film may be composed only of the metal element group MH. Furthermore, the total content of the metal element group MH in the etching mask film may be 99 atomic % or less, or may be 95 atomic % or less, based on all atoms in the etching mask film.

[0064] The types and contents of elements contained in the etching mask film are obtained by XPS. The detailed measurement method of XPS is as explained in the section on the absorber film. The detailed measurement method is explained below.

[0065] The thickness of the etching mask film is preferably 2 nm or more. The thickness of the etching mask film is preferably 30 nm or less, more preferably 25 nm or less, and even more preferably 10 nm or less. The thickness of the etching mask film is determined by XRR.

[0066] The ratio of the thickness of the etching mask film to the total thickness of the absorber film and the etching mask film is preferably 0.05 or more, more preferably 0.1 or more, in order to make it less likely that an altered layer will be formed on the side surface of the absorber film. The thickness ratio is preferably 0.6 or less, more preferably 0.5 or less.

[0067] The etching mask film can be formed by a known film formation method such as DC sputtering, magnetron sputtering, and ion beam sputtering. For example, when forming a Ta film as the etching mask film, the etching mask film can be formed by sputtering using a Ta target and supplying Ar gas. When forming a film containing at least one element selected from the group consisting of N and O as the etching mask film, N can be added to the sputtering gas. ２ Gas and O ２ At least one of the above gases may be introduced. 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 film to be formed can be adjusted.

[0068] As described above, the reflective mask blank of the present invention satisfies the relationship of the above formula (1). Here, the reflective mask blank of the present invention preferably also satisfies the relationship of the following formula (2) in that an altered layer is less likely to occur on the side surface of the absorber film. Formula (2) G ＡＢＳ -G ＨＭ ≧ 150 kJ / mol In formula (2), G ＡＢＳ and G ＨＭ The unit is kJ / mol. ＡＢＳ and G ＨＭ is G in the above formula (1). ＡＢＳ and G ＨＭ This value is calculated in the same manner as above.

[0069] Furthermore, the reflective mask blank of the present invention preferably satisfies the relationship of the following formula (3) in that an altered layer is less likely to occur on the side surface of the absorber film. ＡＢＳ -G ＨＭ ≧ 300 kJ / mol In formula (3), GＡＢＳ and G ＨＭ The unit of is kJ / mol. ＡＢＳ and G ＨＭ is G in the above formula (1). ＡＢＳ and G ＨＭ This value is calculated in the same manner as above.

[0070] [Conductive Film] The reflective mask blank of the present invention may have a conductive film on the surface (second main surface) opposite to the first main surface of the substrate. By providing a conductive film, the reflective mask blank can be handled using an electrostatic chuck. The conductive film preferably has a low sheet resistance. The sheet resistance of the conductive film is preferably, for example, 200 Ω / sq. or less, more preferably 100 Ω / sq. or less. The conductive film may be made of a wide variety of materials described in known literature. For example, a high-dielectric-constant coating described in JP-A-2003-501823, specifically, a coating made of Si, Mo, Cr, CrON, or TaSi, may be used. The conductive film may also be made of a Cr compound containing Cr and one or more elements selected from the group consisting of B, N, O, and C, or a Ta compound containing Ta and one or more elements selected from the group consisting of B, N, O, and C. The thickness of the conductive film is preferably 10 to 1,000 nm, more preferably 10 to 400 nm. The conductive film may also have a function of adjusting stress on the second main surface side of the reflective mask blank. That is, the conductive film can be adjusted to balance the stress from various films formed on the first main surface side and flatten the reflective mask blank. The conductive film can be formed using a known film formation method, for example, a sputtering method such as DC sputtering, magnetron sputtering, or ion beam sputtering, a CVD method, a vacuum deposition method, or an electrolytic plating method.

[0071] <Method for manufacturing a reflective mask and a reflective mask> The reflective mask of the present invention is obtained by patterning the absorber film of the reflective mask blank of the present invention. One example of the method for manufacturing a reflective mask will be described with reference to FIG.

[0072] FIG. 2A shows a state in which a resist pattern 40 is formed on a reflective mask blank having a substrate 12, a multilayer reflective film 14, a protective film 16, an absorber film 18, and an etching mask film 20 in this order. The resist pattern 40 can be formed by a known method, for example, by applying a resist to the etching mask film 20 of the reflective mask blank, followed by exposure and development 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 FIG. 2A as a mask, the etching mask film 20 is etched to pattern the etching mask film into a shape corresponding to the resist pattern 40. The resist pattern 40 is then removed to obtain the laminate shown in FIG. 2B. The etching mask film 20 can be etched by a known method, such as dry etching using an oxygen-containing gas. The resist pattern 40 can also be removed by a known method, such as removal with a cleaning solution. Examples of cleaning liquids include sulfuric acid-hydrogen peroxide solution (SPM), sulfuric acid, ammonia water, ammonia-hydrogen peroxide solution (APM), OH radical cleaning water, and ozone water.

[0073] Next, the absorber film 18 is etched and patterned using the patterned etching mask film 20 shown in Fig. 2(b) as a mask to obtain a laminate having an absorber film pattern 18pt shown in Fig. 2(c). In the laminate shown in Fig. 2(c), the protective film 16 is exposed. Dry etching for forming the absorber film pattern 18pt can be, for example, dry etching using a Cl-based gas or dry etching using an F-based gas. Examples of Cl-based gases include Cl, ２ , SiCl ４ , CHCl ３ , CCl ４ , and BCl ３ Examples of the fluorine-based gas include CF, ... ４ , CHF ３, C ２ F ６ , C ３ F ６ , C ４ F ６ , C ４ F ８ , C.H. ２ F ２ , C.H. ３ F, C ３ F ８ , F ２ , SF ６ , and NF ３ Examples of the gas include gases such as fluorine-based gases, and mixtures thereof. If necessary, in addition to the fluorine-based gas, 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 that the active gas contains oxygen gas. It is also preferable that the etching gas is converted into plasma and used to etch the absorber film 18. In the present invention, an altered layer is unlikely to occur on the side surface of the absorber film pattern 18pt due to the above-mentioned principle.

[0074] Next, the etching mask film 20 is removed from the laminate shown in Fig. 2(c) to obtain the laminate shown in Fig. 2(d). The method for removing the etching mask film 20 can be the same as the method for etching the etching mask film 20 described above.

[0075] Next, as shown in Fig. 2(e), a resist pattern 41 corresponding to the frame of the exposure region is formed on the laminate of Fig. 2(d), and dry etching is performed using the resist pattern 41 of Fig. 2(e) as a mask. Dry etching is performed until it reaches the substrate 12. After dry etching, the resist pattern 41 is removed to obtain the reflective mask shown in Fig. 2(f).

[0076] A reflective mask obtained by patterning the absorber film of the reflective mask blank of the present invention can be suitably used as a reflective mask for exposure to EUV light.

[0077] The present invention will be described in more detail below based on examples. The materials, amounts used, ratios, treatment details, and treatment procedures shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below. Note that Examples 1 to 4, 6 to 10, 12, 13, 15 to 20, and 22 to 29 described below are working examples, and Examples 5, 11, 14, and 21 are comparative examples.

[0078] Example 1 First, the procedure for obtaining the reflective mask blank of Example 1 will be described as a representative example.

[0079] [Substrate] First, as a substrate, SiO ２ -TiO ２ A glass substrate (6-inch (152 mm) square outer diameter, 6.3 mm thick) of this type was prepared. This glass substrate had a thermal expansion coefficient of 0.02×10 at 20° C. －７ / °C, Young's modulus is 67 GPa, Poisson's ratio is 0.17, and specific rigidity is 3.07 × 10 ７ m ２ / s ２ The quality assurance area of ​​the first main surface of the substrate was polished to a root-mean-square roughness (Rq) of 0.15 nm or less and a flatness of 100 nm or less. A 100 nm-thick Cr film was formed on the second main surface of the substrate using magnetron sputtering. The sheet resistance of the Cr film was 100 Ω / sq.

[0080] [Multilayer Reflective Film] Next, a Mo / Si multilayer reflective film was formed on the first main surface of the substrate as a multilayer reflective film. The Mo / Si multilayer reflective film was obtained by repeating the process of forming a Si film (4.5 nm thick) and a Mo film (2.3 nm thick) using an ion beam sputtering method 40 times, and then forming an additional Si film (4.5 nm thick) after the 40th Mo film. The total thickness of the Mo / Si multilayer reflective film was 276.5 nm ((4.5 nm + 2.3 nm) × 40 + 4.5 nm).

[0081] [Protective Film] A Ru film (thickness: 1.0 nm) and a Rh film (thickness: 2.5 nm) were formed in this order as protective films on the multilayer reflective film formed by the above procedure. The Ru film and the Rh film were formed by ion beam sputtering under the following conditions. Ru film formation conditions: Target: Ru target Sputtering gas: Ar gas Gas pressure: 0.027 Pa Ion acceleration voltage: 600 V Film formation rate: 0.056 nm / sec Rh film formation conditions: Target: Rh target Sputtering gas: Ar gas Gas pressure: 0.027 Pa Ion acceleration voltage: 600 V Film formation rate: 0.077 nm / sec

[0082] [Absorber Film] A RuW film (thickness: 40 nm) was formed as an absorber film on the protective film formed by the above procedure. The RuW film was formed by DC sputtering under the following conditions: Target: Ru target, W target Sputtering gas: Ar gas Film formation rate: 0.090 nm / sec Input power density per target area: 7.3 W / cm ２ (Ru target), 7.3 W / cm ２ (Double target)

[0083] [Etching Mask Film] A Ta film (thickness: 15 nm) was formed as an etching mask film on the protective film formed by the above procedure. The Ta film was formed by magnetron sputtering under the following conditions: Target: Ta target, Sputtering gas: Ar gas, Film formation rate: 0.041 nm / sec, Input power density per target area: 6.6 W / cm ２

[0084] By the above procedure, the reflective mask blank of Example 1 was obtained.

[0085] The reflective mask blanks of Examples 2 to 29 were obtained in the same manner as in Example 1, except that the types of absorber film and etching mask film were as shown in the table below. Note that, in the etching mask film of the reflective mask blank of Example 25, the Ru content relative to the total content of Ru and Cr was 40 atomic %, and the Cr content relative to the total content of Ru and Cr was 60 atomic %.

[0086] <Evaluation> For the reflective mask blanks of Examples 1 to 5, 10 to 18, 20 to 23, and 25 to 29, a line and space pattern was formed on the etching mask film, and the etching mask film was processed into the line and space pattern to form an etching mask film pattern. Next, using the etching mask film pattern as a mask, an ICP etching device was used to pattern the absorber film. ICP antenna bias output: 1200 W Substrate bias output: 50 W Etching gas: CF ４ Gas and O ２ Mixture of gases (flow ratio CF ４ :O ２ = 5:95 (total flow rate: 60 sccm) Etching pressure: 4.0 × 10 －１ Pa

[0087] The absorber films of the reflective mask blanks of Examples 6 to 9, 19 and 24 were patterned under the following conditions: ICP antenna bias output: 1200 W, substrate bias output: 50 W, etching gas: Cl ２ Gas and O ２ Gas mixture (flow ratio Cl ２ :O ２ = 1:1 (total flow rate: 90 sccm) Etching pressure: 4.0 × 10 －１ Pa

[0088] After etching the absorber film of each reflective mask blank under the above conditions, the cross section of the reflective mask blank was observed using a transmission electron microscope to confirm whether or not an altered layer had formed on the side surface of the processed absorber film, and the average thickness of the altered layer was measured. Specifically, a thin section sample with an exposed cross section perpendicular to the longitudinal direction of the line-and-space pattern was prepared using a Helios 1200 manufactured by FEI Japan. Specifically, a Ga ion beam was irradiated to prepare a thin section sample with a thickness of 50 to 100 nm. The thin section sample was observed using a transmission electron microscope. The transmission electron microscope used was an ARM200F manufactured by JEOL Ltd., and the acceleration voltage was set to 200 kV. In the observation image (dark-field image), it was confirmed whether or not a layer (altered layer) with a different contrast had formed on the side surface of the processed absorber film compared to the unprocessed portion of the absorber film. If an altered layer had formed, the thickness of the altered layer was measured at any five locations. If no altered layer was observed, the thickness of the altered layer was recorded as 0 nm. The above observation was performed in five visual fields, and the average thickness was calculated as the arithmetic mean value of the thicknesses of the altered layer at 25 locations. Based on the average thickness of the altered layer, the degree of occurrence of the altered layer was evaluated according to the following criteria. In practice, an A rating or a B rating is preferable, with an A rating being more preferable. A: No altered layer was observed, or the average thickness of the altered layer was less than 1 nm. B: The average thickness of the altered layer was 1 nm or more but less than 3 nm. C: The average thickness of the altered layer was 3 nm or more.

[0089] <Results> Table 1 shows the type of absorber film and the type of etching mask film of the reflective mask blank of each example, as well as the evaluation results. In Table 1, the content of each element in the absorber film and the etching mask film was calculated by the method described above. In Table 1, the film thickness of the absorber film and the etching mask film was measured by the method described above. In Table 1, "at%" means atomic %. In Table 1, the column "Left side of formula (1)" is the calculated value of the left side of the above formula (1). In Table 1, "CFO" means CF ４ Gas and O ２ In Table 1, "CLO" indicates that a mixture of Cl and ClO gases was used to etch the absorber film. ２ Gas and O ２1 shows a mixture of gases used to etch the absorber film.

[0090]

[0091] From the results shown in Table 1, it was confirmed that when the value of the left side of formula (1) is 100 kJ / mol or more, an altered layer is less likely to occur compared to when the value of the left side of formula (1) is less than 100 kJ / mol. The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2024-089978, filed on June 3, 2024, are hereby incorporated by reference as part of the disclosure of the present invention.

[0092] REFERENCE SIGNS LIST 10 Reflective mask blank 12 Substrate 14 Multilayer reflective film 16 Protective film 18 Absorber film 18pt Absorber film pattern 20 Etching mask film 40, 41 Resist pattern

Claims

1. A reflective mask blank having, in this order, a substrate, a multilayer reflective film that reflects EUV light, an absorber film containing two or more metal elements, and an etching mask film containing one or more metal elements, which satisfies the relationship of the following formula (1): Formula (1) G ＡＢＳ -G ＨＭ ≧ 100 kJ / mol In formula (1), G ＡＢＳ and G ＨＭ The unit is kJ / mol. ＡＢＳ is a value obtained by multiplying the standard Gibbs energy of formation of an oxide of each metal element in the metal element group MA by the atomic ratio of the content of each metal element in the metal element group MA to the total content of the metal element group MA, when the metal elements contained in the absorber film are defined as a metal element group MA. ＨＭ is the value of the standard Gibbs energy of formation of an oxide of a metal element in the metal element group MH when the metal elements contained in the etching mask film are defined as a metal element group MH and the metal element group MH consists of only one type of metal element; and is the value obtained by summing up the calculated values ​​obtained by multiplying the standard Gibbs energy of formation of an oxide of each metal element in the metal element group MH by the atomic ratio of the content of each metal element in the metal element group MH to the total content of the metal element group MH when the metal element group MH consists of two or more types of metal elements.

2. The reflective mask blank according to claim 1, wherein the group of metal elements MA includes at least one metal element selected from the group consisting of ruthenium, palladium, iridium, platinum, silver, nickel, and cobalt.

3. A reflective mask blank according to claim 1 or 2, wherein the group of metal elements MH includes at least one metal element selected from the group consisting of ruthenium, rhodium, aluminum, chromium, silicon, tantalum, titanium, hafnium, and yttrium.

4. A reflective mask blank according to claim 1 or 2, wherein the group of metal elements MA contains ruthenium and at least one metal element selected from the group consisting of chromium, tungsten, niobium, and tantalum.

5. A reflective mask blank according to claim 1 or 2, wherein the group of metal elements MA contains iridium and at least one metal element selected from the group consisting of chromium, ruthenium, tungsten, niobium, and tantalum.

6. A reflective mask blank according to claim 1 or 2, wherein the group of metal elements MA contains platinum and at least one metal element selected from the group consisting of chromium, ruthenium, tungsten, niobium, and tantalum.

7. The reflective mask blank according to claim 1 or 2, wherein the group of metal elements MA includes platinum and ruthenium.

8. A reflective mask blank according to claim 1 or 2, wherein the group of metal elements MA includes at least one metal element selected from the group consisting of nickel and cobalt.

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

10. A reflective mask blank according to claim 1 or 2, wherein the group of metal elements MH includes at least one metal element selected from the group consisting of ruthenium, aluminum, chromium, and tantalum.

11. The reflective mask blank according to claim 3, wherein the etching mask film further contains at least one element selected from the group consisting of boron, carbon, nitrogen and oxygen.

12. A reflective mask blank according to claim 1 or 2, further comprising a protective film between said absorber film and said multilayer reflective film, said protective film containing 50 atomic % or more of rhodium relative to all atoms of said protective film.

13. The reflective mask blank according to claim 1 or 2, which satisfies the relationship of the following formula (2): Formula (2) G ＡＢＳ -G ＨＭ ≧ 150 kJ / mol In formula (2), G ＡＢＳ and G ＨＭ The unit is kJ / mol.

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

15. A method for manufacturing a reflective mask, comprising the step of patterning the absorber film of the reflective mask blank according to claim 1 or 2.

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