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

Abstract

To provide a reflective mask blank with a phase shift film featuring low crystallinity and superior hydrogen resistance.SOLUTION: A reflective mask blank has a substrate, a multilayer reflective film that reflects EUV light, a protective film, and a phase shift film that shifts the phase of EUV light, in the stated order. The phase shift film at least includes ruthenium and carbon. As calculated by the X-ray reflectance method, the phase shift film has a density of 8.0 g / cm3 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[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 a film with low EUV light reflectivity is patterned on the multilayer reflective film. For the purpose of achieving even higher resolution, a phase-shift film may be used as the film with low EUV light reflectivity. A phase-shift film is a film that imparts a phase difference to transmitted EUV light, and the reflection of EUV light is reduced due to interference between EUV light rays with this phase difference. Furthermore, when patterning the low-reflectivity film mentioned above, a protective film is often placed between the multilayer reflective film and the low-reflectivity film to protect the multilayer reflective film.

[0004] When a phase-shift film is used as a low-reflectivity film for a reflective mask, EUV light incident on the reflective mask from the illumination optical system of the exposure apparatus is reflected in areas without the phase-shift film (apers), while reflection is reduced in areas with the phase-shift film (non-apers). As a result, the mask pattern is transferred as a resist pattern onto the wafer through the reduction projection optical system of the exposure apparatus, and subsequent processing is carried out.

[0005] As an example of a reflective mask blank used for the patterning described above, Patent Document 1 discloses an embodiment having a multilayer reflective film, a protective film, a phase-shift film, and an etching mask film on a substrate. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 6929983 [Overview of the initiative] [Problems that the invention aims to solve]

[0007] In phase-shift films of reflective mask blanks, low crystallinity is required to suppress variations in line width during patterning.

[0008] Furthermore, in EUV lithography, exposure contamination occurs, such as the deposition of a carbon film on the reflective mask due to EUV light. Therefore, a method of introducing hydrogen gas into the exposure atmosphere is being investigated to suppress exposure contamination. When hydrogen gas is introduced into the exposure atmosphere, the reflective mask comes into contact with the hydrogen gas. Since hydrogen gas is reducing, it can reduce the materials constituting the phase-shift film, potentially altering its composition and thickness. Changes in the composition and thickness of the phase-shift film are undesirable because they alter the amount of phase shift, preventing the desired reflection characteristics from being achieved. Therefore, phase-shift films must exhibit minimal changes when exposed to hydrogen gas; in other words, hydrogen resistance is also required.

[0009] When the inventors examined the reflective mask blank described in Patent Document 1, they found that there is room for improvement in hydrogen resistance.

[0010] Therefore, the present invention aims to provide a reflective mask blank having a phase-shift film with low crystallinity and excellent hydrogen resistance. Furthermore, the present invention also aims to provide a method for manufacturing a reflective mask blank, a reflective mask, and a method for manufacturing a reflective mask. [Means for solving the problem]

[0011] As a result of diligent research into the above-mentioned problems, the inventors of the present invention have found that the above-mentioned problems can be solved by having a phase-shift film containing at least ruthenium and carbon, and by having a phase-shift film with a density above a predetermined level, thereby completing the present invention.

[0012] In other words, the inventors found that the above problem could be solved by the following configuration. [1] A circuit board and A multilayer reflective film that reflects EUV light, Protective film and, A reflective mask blank having, in this order, a phase-shifting film that shifts the phase of EUV light, The above phase-shift film comprises at least ruthenium and carbon, The density of the above phase-shift film, calculated by X-ray reflectivity, is 8.0 g / cm³. 3 That concludes the description of the reflective mask blank. [2] The reflective mask blank according to [1], wherein the carbon content in the phase-shift film is 48.0 atomic% or less relative to the total atoms of the phase-shift film. [3] The reflective mask blank according to [1] or [2], wherein the carbon content in the phase-shift film is 4.0 to 30.0 atomic percent relative to the total atoms of the phase-shift film. [4] A reflective mask blank according to any one of [1] to [3], wherein, in the spectrum obtained when the above phase-shift film is analyzed by X-ray photoelectron spectroscopy, the maximum intensity of the peak at a binding energy of 278 to 282 eV is P0, and the maximum intensity of the peak at a binding energy of 282 to 286 eV is P1, satisfies the following equation (I). Equation (I) P0 / P1 ≥ 1.50 〔5〕 The reflective mask blank according to any one of 〔1〕 to 〔4〕, wherein the phase shift film further contains at least one element of hydrogen, boron, nitrogen, and oxygen. 〔6〕 The reflective mask blank according to 〔5〕, wherein the total content of hydrogen and nitrogen contained in the phase shift film is 10 atomic% or less with respect to all atoms of the phase shift film. 〔7〕 The reflective mask blank according to any one of 〔1〕 to 〔6〕, wherein the phase shift film further contains one or more elements selected from the group consisting of chromium, zirconium, niobium, molybdenum, hafnium, tantalum, tungsten, rhenium, osmium, and iridium. 〔8〕 The reflective mask blank according to 〔7〕, wherein the total content of one or more elements selected from the group consisting of chromium, zirconium, niobium, molybdenum, hafnium, tantalum, tungsten, rhenium, osmium, and iridium contained in the phase shift film is 50 atomic% or less with respect to all atoms of the phase shift film. 〔9〕 The reflective mask blank according to any one of 〔1〕 to 〔8〕, wherein the refractive index of the phase shift film with respect to EUV light having a wavelength of 13.5 nm is 0.920 or less. 〔10〕 The reflective mask blank according to any one of 〔1〕 to 〔9〕, wherein the attenuation coefficient of the phase shift film with respect to EUV light having a wavelength of 13.5 nm is 0.0130 or more. 〔11〕 The manufacturing method according to any one of 〔1〕 to 〔10〕, wherein the film thickness of the phase shift film is 60 nm or less. 〔12〕 The reflective mask blank according to any one of 〔1〕 to 〔11〕, further having a hard mask film on the side opposite to the substrate side of the phase shift film. 〔13〕 The reflective mask blank according to 〔12〕, wherein the hard mask film contains tantalum. 〔14〕 The reflective mask blank according to 〔12〕 or 〔13〕, wherein the hard mask film further contains one or more elements selected from the group consisting of boron, carbon, nitrogen, and oxygen. 〔15〕The reflective mask blank according to any one of 〔1〕~〔14〕, further having a buffer film between the phase shift film and the protective film. 〔16〕The reflective mask blank according to 〔15〕, wherein the buffer film contains one or more elements selected from the group consisting of tantalum and chromium. 〔17〕The reflective mask blank according to 〔15〕 or 〔16〕, wherein the buffer film further contains one or more elements selected from the group consisting of boron, carbon, nitrogen, and oxygen. 〔18〕The reflective mask blank according to any one of 〔15〕~〔17〕, wherein the refractive index of the buffer film with respect to EUV light having a wavelength of 13.5 nm is 0.920 to 0.970, and the attenuation coefficient of the buffer film with respect to EUV light having a wavelength of 13.5 nm is 0.0150 to 0.0400. 〔19〕The reflective mask blank according to any one of 〔15〕~〔18〕, wherein the film thickness of the buffer film is 10 nm below. 〔20〕A method for manufacturing the reflective mask blank according to any one of 〔1〕~〔19〕, wherein the phase shift film is formed by a sputtering method, and elemental carbon or metal carbide is used as at least one of the targets of the sputtering method. 〔21〕A method for manufacturing the reflective mask blank according to any one of 〔1〕~〔19〕, wherein the phase shift film is formed by a reactive sputtering method, and a gas containing a gas of a compound containing carbon atoms is used as the gas used in the reactive sputtering method. 〔22〕The method for manufacturing the reflective mask blank according to 〔21〕, wherein the gas containing a compound containing carbon atoms contains one or more selected from the group consisting of methane gas, ethane gas, ethylene gas, acetylene gas, and carbon dioxide. 〔23〕A reflective mask having a phase shift film pattern formed by patterning the phase shift film of the reflective mask blank according to any one of 〔1〕~〔19〕.

[24] A method for manufacturing a reflective mask, comprising the step of patterning the above-mentioned phase-shift film of a reflective mask blank described in any one of [1] to

[19] . [Effects of the Invention]

[0013] According to the present invention, a reflective mask blank having a phase-shift film with low crystallinity and excellent hydrogen resistance can be provided. Furthermore, according to the present invention, a method for manufacturing a reflective mask blank, a reflective mask, and a method for manufacturing a reflective mask can also be provided. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram showing an example of a reflective mask blank of the present invention. [Figure 2] This is a schematic diagram illustrating an example of the manufacturing process for a reflective mask using the reflective mask blank of the present invention. [Modes for carrying out the invention]

[0015] The present invention will be described in detail below. The following description of the constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.

[0016] The meaning of each term used in this specification is shown below. In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. In this specification, each element may be represented by its corresponding element symbol.

[0017] <Reflective Mask Blank> This is a reflective mask blank comprising, in this order, a substrate, a multilayer reflective film that reflects EUV light, a protective film, and a phase-shift film that shifts the phase of EUV light. Here, the phase-shift film contains at least ruthenium (Ru) and carbon (C), and the density of the phase-shift film calculated by X-ray reflectometry (XRR) is 8.0 g / cm³. 3 That's all.

[0018] The reflective mask blank of the present invention will be described below with reference to the drawings. As shown in Figure 1, the reflective mask blank 10 has a substrate 12, a multilayer reflective film 14, a protective film 16, and a phase shift film 18 in that order. The phase-shift film 18 contains at least Ru and C. Furthermore, the density of the phase-shift film 18, calculated by XRR, is 8.0 g / cm³. 3 That's all.

[0019] The mechanism by which the phase-shift film of the reflective mask blank of the present invention exhibits low crystallinity and excellent hydrogen resistance is not entirely clear, but the inventors speculate as follows. The phase-shift film of the present invention contains Ru, but also contains C, and therefore its crystallinity tends to be low due to the influence of C. On the other hand, carbon itself can be reduced by hydrogen to become a hydrocarbon gas, but as in the phase-shift membrane of the present invention, the density is 8.0 g / cm³. 3 As a result of the above, the phase-shift film becomes denser, which suppresses the penetration of hydrogen into the film, and it is thought that the carbon contained in the phase-shift film becomes less susceptible to reduction by hydrogen. Furthermore, even if Ru is reduced by hydrogen, it is unlikely to become a volatile component. As a result, the phase-shift film of the reflective mask blank of the present invention is thought to have excellent hydrogen resistance. The following describes the configurations that the reflective mask blank of the present invention may have, and configurations that it may have.

[0020] [substrate] The substrate of the reflective mask blank of the present invention preferably has a small coefficient of thermal expansion. A smaller coefficient of thermal expansion of the substrate helps to suppress distortion of the phase-shift film pattern due to heat during exposure with EUV light. The thermal expansion coefficient of the substrate is 0 ± 1.0 × 10 at 20°C. -7 A temperature of / ℃ is preferred, and 0±0.3×10 -7 / ℃ is preferable. Materials with a low coefficient of thermal expansion include SiO2-TiO2 glass, but are not limited to these; crystallized glass with precipitated β-quartz solid solution, quartz glass, metallic silicon, and metal substrates can also be used. For SiO2-TiO2 glass, it is preferable to use quartz glass containing 90-95% by mass of SiO2 and 5-10% by mass of TiO2. When the TiO2 content is 5-10% by mass, the coefficient of linear expansion at room temperature is approximately zero, and there is almost no dimensional change at room temperature. Note that SiO2-TiO2 glass may also contain trace components other than SiO2 and TiO2.

[0021] The side of the substrate on which the multilayer reflective film is laminated (hereinafter also referred to as the "first main surface") preferably has high surface smoothness. The surface smoothness of the first main surface can be evaluated by its 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. Surface roughness can be measured with an atomic force microscope, and the surface roughness will be described as root mean square roughness Rq based on JIS-B0601. The first main surface is preferably surface-processed to a predetermined flatness, in order to improve the pattern transfer accuracy and positional accuracy of the reflective mask obtained using a reflective mask blank. In a predetermined area of ​​the first main surface of the substrate (for example, an area of ​​132 mm × 132 mm), the flatness is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less. The flatness can be measured using a flatness measuring instrument manufactured by Fujinon Corporation. The size and thickness of the substrate are determined as appropriate based on the design values ​​of the mask, etc. For example, the outer dimensions may be 6 inches (152 mm) square and the thickness 0.25 inches (6.3 mm). Furthermore, the substrate preferably has high rigidity in order to prevent deformation due to film stress in the film (multilayer reflective film, phase-shift film, etc.) formed on the substrate. For example, the Young's modulus of the substrate is preferably 65 GPa or higher.

[0022] [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 of the EUV mask blank. The multilayer reflective film preferably has a high reflectivity to EUV light. Specifically, when EUV light is incident on the surface of the multilayer reflective film at an incident angle of 6°, the maximum reflectivity of EUV light around a wavelength of 13.5 nm is preferably 60% or more, and more preferably 65% ​​or more. Similarly, even when a protective film is laminated on the multilayer reflective film, the maximum reflectivity of EUV light around a wavelength of 13.5 nm is preferably 60% or more, and more preferably 65% ​​or more.

[0023] Because multilayer reflective films can achieve high reflectivity of EUV light, they typically use a multilayer reflective film in which a high refractive index layer, which exhibits a high refractive index for EUV light, and a low refractive index layer, which exhibits a low refractive index for EUV light, are alternately stacked multiple times. The multilayer reflective film may be constructed by stacking a high refractive index layer and a low refractive index layer in that order from the substrate side, with each stacking period comprising multiple cycles, or by stacking a low refractive index layer and a high refractive index layer in that order, with each stacking period comprising multiple cycles. A layer containing Si can be used as the high refractive index layer. In addition to pure Si, Si compounds containing one or more elements selected from the group consisting of B, C, N, and O can be used as the Si-containing material. By using a high refractive index layer containing Si, a reflective mask with excellent EUV light reflectivity can be obtained. As the low refractive index layer, a layer containing a metal selected from the group consisting of Mo, Ru, Rh, and Pt, or an alloy thereof, can be used. Si is widely used in the high refractive index layer, and Mo is widely used in the low refractive index layer. In other words, Mo / Si multilayer reflective films are the most common. However, multilayer reflective films are not limited to these, 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, and Si / Ru / Mo / Ru multilayer reflective films can also be used.

[0024] The film thickness of each layer constituting a multilayer reflective film and the number of repeating units in each layer can be appropriately selected according to the film material used and the required EUV light reflectivity of the reflective layer. Taking a Mo / Si multilayer reflective film as an example, to create a multilayer reflective film with a maximum EUV light reflectivity 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.

[0025] Each layer constituting the multilayer reflective film can be deposited to a desired thickness using known deposition methods such as 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 targets made of a high refractive index material and targets made of a low refractive index material. If the multilayer reflective film is a Mo / Si multilayer reflective film, for example, using ion beam sputtering, first a Si layer of a predetermined thickness is deposited on the substrate using a Si target. Then, a Mo layer of a predetermined thickness is deposited using a Mo target. By stacking these Si and Mo layers for 30 to 60 periods, with each period representing one cycle, a Mo / Si multilayer reflective film is formed.

[0026] [Protective film] The protective film on the reflective mask blank of the present invention 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 phase-shift film by the etching process. Materials that can achieve the above objective include materials containing at least one element selected from the group consisting of Ru and Rh. In other words, it is preferable that the protective film contains at least one element selected from the group consisting of Ru and Rh. More specifically, the above materials include elemental Ru metal, Ru alloys containing Ru and one or more metals selected from the group consisting of Si, Ti, Nb, Mo, Rh, and Zr, Rh metal, Rh alloys containing Rh and one or more metals selected from the group consisting of Si, Ti, Nb, Mo, Ru, Ta, and Zr, Rh-containing nitrides containing the above Rh alloy and N, and Rh-containing oxynitrides containing the above Rh alloy, N, and O, among other Rh-based materials. Furthermore, examples of materials that can achieve the above objectives include Al, nitrides containing these metals and N, and Al2O3. Among these, Ru elemental metal, Ru alloy, Rh elemental metal, or Rh alloy are preferred as materials that can achieve the above objectives. As Ru alloys, Ru-Si alloys and Ru-Rh alloys are preferred, and as Rh alloys, Rh-Si alloys and Rh-Ru alloys are preferred.

[0027] The thickness of the protective film is not particularly limited as long as it can perform its function as a protective film. In order to maintain the reflectance of EUV light reflected by the multilayer reflective film, the thickness of the protective film is preferably 1 to 10 nm, more preferably 1.5 to 6 nm, and even more preferably 2 to 5 nm. It is also 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 is the preferred thickness described above.

[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 preferred material described above. Furthermore, if the protective film is a multilayer film, it is also preferable that the total thickness of the multilayer film is within the preferred range described above.

[0029] The protective film can be deposited using known deposition methods such as magnetron sputtering and ion beam sputtering. When depositing a Ru film by magnetron sputtering, it is preferable to use a Ru target as the target and Ar gas as the sputtering gas.

[0030] [Phase-shift membrane] The phase-shift film of the reflective mask blank of the present invention contains at least Ru and C. Furthermore, the density of the phase-shift film, calculated by XRR, is 8.0 g / cm³. 3 That's all. The phase-shift film only needs to satisfy the above requirements. For example, if the phase-shift film contains elements other than Ru and C, the content of those elements may vary in the thickness direction of the phase-shift film.

[0031] The carbon content in the phase-shift film is preferably 48.0 atomic% or less, more preferably 30.0 atomic% or less, even more preferably 25.0 atomic% or less, particularly preferably 18.0 atomic% or less, and most preferably 17.0 atomic% or less, relative to the total atoms of the phase-shift film, in order to further reduce the refractive index n of the phase-shift film as described later. The carbon content in the phase-shift film is preferably 4.0 atomic% or more, and more preferably 6.0 atomic% or more, relative to the total atoms of the phase-shift film, in terms of lowering crystallinity. Furthermore, the carbon content in the phase-shift film is preferably 4.0 to 30.0 atomic%, more preferably 4.0 to 18.0 atomic%, even more preferably 6.0 to 18.0 atomic%, and particularly preferably 6.0 to 17.0 atomic%, in terms of superior hydrogen resistance.

[0032] The Ru atom content in the phase-shift film is preferably 96.0 atomic% or less, and more preferably 90.0 atomic% or less, relative to the total atoms of the phase-shift film, in terms of lowering crystallinity. The Ru atom content in the phase-shift film is preferably 45.0 atomic% or more, more preferably 50.0 atomic% or more, and even more preferably 55.0 atomic% or more, relative to the total atoms of the phase-shift film, in order to further reduce the refractive index n of the phase-shift film as described later.

[0033] The phase-shift film contains Ru and C, but may also contain other elements besides Ru and C. Other elements that may be included in the phase-shift film include, for example, one or more elements selected from the group consisting of H, B, N, and O, and it is preferable that the phase-shift film contains at least one of H and N. When the phase-shift film contains at least one of H and N, the total content of H and N is preferably 10 atomic% or less relative to the total atoms of the phase-shift film, more preferably 8 atomic% or less, and even more preferably 6 atomic% or less, in terms of making the refractive index n of the phase-shift film, as described later, smaller. There is no particular lower limit to the total content, but for example, 0.1 atomic% or more is an example. Note that the phase-shift film does not have to contain the above nonmetallic elements (e.g., H, B, N, and O).

[0034] Other elements that may be included in the phase-shift film include, for example, Group 4, Group 5, Group 6, and Group 7 elements, with one or more elements selected from the group consisting of Cr, Zr, Nb, Mo, Hf, Ta, W, Re, Os, and Ir being preferred, one or more elements selected from the group consisting of Cr, Nb, Hf, Ta, and Re being more preferred, and one or more elements selected from the group consisting of Cr and Re being even more preferred. When the phase-shift film contains one or more elements selected from the group consisting of Cr, Zr, Nb, Mo, Hf, Ta, W, Re, Os, and Ir, the total content is preferably 50 atomic% or less relative to the total atoms of the phase-shift film, more preferably 40 atomic% or less, and even more preferably 30 atomic% or less, in terms of making the refractive index n of the phase-shift film, as described later, smaller. Furthermore, the total content is preferably 2 atomic% or more, and more preferably 4 atomic% or more, in terms of making the crystallinity smaller.

[0035] Examples of materials that constitute the phase-shift film include RuC, RuCH, RuCN, RuCNH, RuCrC, RuCrCN, RuZrC, RuZrCN, RuNbC, RuNbCN, RuMoC, RuMoCN, RuHfC, RuHfCN, RuTaC, RuTaCN, RuWC, RuWCN, RuReC, and RuReCN, RuOsC, RuOsCN, RuIrC, and RuIrCN. Among these, RuC, RuCN, RuCrC, RuCrCN, or RuReC are preferred. Note that "RuCN" refers to a material containing Ru, C, and N. The preferred content of each element is as described above.

[0036] In this specification, the types and content of elements contained in a phase-shift film are obtained by X-ray photoelectron spectroscopy (XPS). In addition to XPS, the types and content of elements contained in the phase-shift film may also be obtained by combining at least one of Rutherford backscattering spectroscopy (RBS) and secondary ion mass spectrometry (SIMS). First, the content of elements other than Ru and C in the phase-shift film is quantified using XPS. If the reflective mask blank has other layers on the side opposite to the substrate side of the phase-shift film, the other layers are removed by sputtering or other means before measurement. For Ru and C, the content may be analyzed using a combination of XPS and RBS or SIMS. The detailed measurement conditions for XPS, RBS, and SIMS shall follow the methods described in the later examples.

[0037] The phase-shift film in the reflective mask blank of the present invention has a density calculated by XRR (hereinafter also referred to as "density of the phase-shift film") of 8.0 g / cm³. 3 That's all. In this specification, to calculate the density of the phase shift film by XRR, SmartLab SE manufactured by Rigaku Corporation is used as the measuring device. As the X-ray source, CuKα rays are used, the tube voltage is 40 kV, and the tube current is 50 mA. The attached software (SmartLab Studio II) is used for analysis. For the XRR measurement, a reflective mask blank or a sample obtained by cutting a reflective mask blank into an appropriate size can be used as the measurement sample. The density of the phase shift film is preferably 9.0 g / cm 3 or more, more preferably 10.0 g / cm 3 or more. The upper limit of the density of the phase shift film is not particularly limited, but is often 20.0 g / cm 3 or less.

[0038] The film thickness of the phase shift film is preferably 60 nm or less, more preferably 50 nm or less, and even more preferably 40 nm or less. The lower limit of the film thickness of the phase shift film is not particularly limited, but is preferably 15 nm or more. The film thickness of the phase shift film is determined by XRR.

[0039] Also, in the spectrum obtained when the phase shift film is analyzed by XPS, when the maximum intensity of the peak at a binding energy of 278 to 282 eV is P0 and the maximum intensity of the peak at a binding energy of 282 to 286 eV is P1, it is also preferable to satisfy the following formula (I). Formula (I) P0 / P1 ≧ 1.50 When the above formula (I) is satisfied, it is easier to obtain a phase shift film with more excellent hydrogen resistance. The detailed measurement conditions of XPS shall follow the method described in the examples in the subsequent section. The value of P0 / P1 is preferably 1.54 or more, more preferably 1.60 or more, and even more preferably 1.65 or more.

[0040] The crystallinity of the phase-shift film formed by the reflective mask blank of the present invention is low. Low crystallinity of the phase-shift film means that the crystallite size calculated using the diffraction chart obtained by X-ray diffraction (XRD) is small. Scherrer's formula is used to calculate the crystallite size. In Scherrer's formula, the full width at half maximum of the diffraction peak with the highest intensity in the range of 2θ from 30 to 55° is used. If no clear diffraction peak is observed in the above diffraction chart, the phase-shift film can be said to be amorphous. The detailed measurement conditions for the XRD method shall follow the method described in the examples below. In the present invention, the crystallite size of the phase-shift film is preferably 10.0 nm or less, more preferably 7.0 nm or less, and even more preferably 6.0 nm or less. Furthermore, the phase-shift film of the present invention may be amorphous.

[0041] The refractive index n of the phase-shift film with respect to EUV light at a wavelength of 13.5 nm is preferably 0.950 or less, more preferably 0.920 or less, even more preferably 0.915 or less, and particularly preferably 0.910 or less, as this allows for a thinner film thickness of the phase-shift film. The lower limit of the refractive index n is not particularly limited, but it is 0.860 or more, and preferably 0.870 or more. The extinction coefficient k of the phase-shift film for EUV light at a wavelength of 13.5 nm is preferably 0.0100 or higher, more preferably 0.0130 or higher, even more preferably 0.0140 or higher, and particularly preferably 0.0140 or higher, as this makes it easier to adjust the reflectivity of the phase-shift film to a lower value. There is no particular upper limit to the extinction coefficient k, but a value of 0.0600 or lower is acceptable. The refractive index n and extinction coefficient k mentioned above are determined by measuring the incident angle dependence of the reflectance using EUV light with a wavelength of 13.5 nm, and then fitting the resulting profile with the refractive index n and extinction coefficient k as parameters.

[0042] The EUV light reflectivity of the phase-shift film is preferably 2% or higher. To obtain a sufficient phase-shift effect, the EUV light reflectivity of the phase-shift film is preferably 4-15%. When a phase-shift film patterned as a reflective mask is used, the contrast of the optical image on the wafer is improved and the exposure margin is increased.

[0043] Phase-shift films can be formed using known film deposition methods such as sputtering (magnetron sputtering, ion beam sputtering, and reactive sputtering).

[0044] When forming a phase-shift film by sputtering (e.g., magnetron sputtering and ion beam sputtering), at least one of the targets for the sputtering method can be, for example, a metal carbide. Examples of metal carbides include Ru carbide, carbides of one or more elements selected from the group consisting of Cr, Zr, Nb, Mo, Hf, Ta, W, Re, Os, and Ir, composite carbides containing those elements, and mixtures thereof. Furthermore, when using a target that does not contain Ru as a metal carbide, the phase-shift film of the present invention can be formed by sputtering the metal carbide from that target and also by sputtering from a target that contains at least Ru. The method of forming a film by sputtering the material constituting the target from multiple targets is also called co-sputtering or co-sputtering method. That is, when using a target that does not contain Ru as a metal carbide, the phase-shift film of the present invention can be formed by co-sputtering using that target and a target that contains Ru. Furthermore, at least one of the targets for the sputtering method may be, for example, a single C element. When at least one of the targets is a single C atom, the phase-shift film of the present invention can be formed by sputtering from a single C target and from a target containing at least Ru. In other words, the phase-shift film of the present invention can be formed by co-sputtering using a single C target and a Ru-containing target. A "single C target" refers to a target that mainly contains C, and the C content is preferably 99 atomic% or more, and more preferably 99.9 atomic% or more, relative to the total atoms of the target. The upper limit of the C content is less than 100 atomic%.

[0045] Furthermore, when forming a phase-shift film by reactive sputtering, it is preferable to use a gas containing a compound containing carbon (C) as the gas used in the reactive sputtering method. The gas containing carbon (C) is preferably one or more selected from the group consisting of methane, ethane, ethylene, acetylene, and carbon dioxide, and more preferably a gas containing methane. The gas used in the reactive sputtering method may also preferably contain gases other than those containing carbon (C). The gas other than those containing carbon (C) is preferably an inert gas, more preferably N2, or more preferably Ar, Kr, or Xe. When using reactive sputtering, for example, by sputtering from a target containing at least Ru, the phase-shift film of the present invention can be formed. Furthermore, by using a gas containing a desired element in the reactive sputtering process, that element can be incorporated into the phase-shift film. For example, by using a gas containing N2 in the reactive sputtering process, a phase-shift film containing N can be formed.

[0046] The sputtering conditions described above can be adjusted as appropriate. For example, the elemental content in the phase-shifted film and the physical properties of the phase-shifted film can be controlled by adjusting the sputtering conditions, the target used, and the gas used. For example, the carbon content can be adjusted by the carbon content in the target used, as well as the energy and amount of ions supplied to the target. The carbon content can also be adjusted by the concentration of carbon-containing compounds in the gas used for sputtering. Furthermore, the density of the phase-shift film can be adjusted by, for example, the type of elements contained in the target, the deposition rate, the energy of ions supplied to the target, and the type and amount of gas used for sputtering. More specifically, the density of the phase-shift film can be increased by, for example, increasing the deposition rate, increasing the energy of ions supplied to the target, decreasing the amount of gas supplied for sputtering, lowering the deposition pressure, reducing the substrate-target distance, and decreasing the content of reactive gases (e.g., gases containing C) in the gas used for sputtering. Furthermore, even when using a film deposition method other than sputtering, the elemental content and physical properties of the phase-shift film can be controlled by known means.

[0047] [Buffer membrane] The reflective mask blank of the present invention may further have a buffer film between the phase-shift film and the protective film. If the reflective mask blank of the present invention has a buffer film, the thickness of the phase shift film can be further reduced in some cases.

[0048] The buffer film preferably contains one or more elements selected from the group consisting of Ta and Cr. Furthermore, the buffer film may also preferably contain one or more elements selected from the group consisting of B, C, N, and O. As for the material constituting the buffer film, for example, a material containing Ta and one or more elements selected from the group consisting of B, C, N, and O is preferred, and TaBN or TaBO is more preferred. "TaBN" represents a material containing Ta, B, and N. If the buffer film contains one or more elements selected from the group consisting of Ta and Cr, the content of one or more elements selected from the group consisting of Ta and Cr is preferably 50 atomic% or more, and more preferably 70 atomic% or more. The elements and their amounts contained in the buffer film can be obtained using the same method as for the phase-shift film.

[0049] The buffer film thickness is preferably 0.5 to 25 nm. In particular, the buffer film thickness is preferably 10 nm or less, as this further reduces the total thickness of the buffer film and the phase shift film. The thickness of the buffer film can be measured using XRR.

[0050] The refractive index n of the buffer film with respect to EUV light at a wavelength of 13.5 nm is preferably 0.930 to 0.970. Furthermore, the extinction coefficient k of the buffer film with respect to EUV light at a wavelength of 13.5 nm is preferably 0.0150 to 0.0400. The refractive index n and extinction coefficient k can be measured in the same manner as the phase-shift film described above.

[0051] The buffer film can be formed by known film deposition methods, such as sputtering methods including magnetron sputtering and ion beam sputtering.

[0052] [Conductive film on the back surface] The reflective mask blank of the present invention may have a back surface conductive film on the surface (second main surface) opposite to the first main surface of the substrate. By providing a back surface conductive film, the reflective mask blank can be handled by an electrostatic chuck. The conductive film on the back surface is preferably low in sheet resistance. The sheet resistance of the conductive film on the back surface is preferably 200 Ω / sq. or less, and more preferably 100 Ω / sq. or less. The constituent materials for the back surface 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 materials for the back surface conductive film may be 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 on the back surface is preferably 10 to 1000 nm, and more preferably 10 to 400 nm. Furthermore, the back surface 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 back surface conductive film can balance the stress from the various films formed on the first main surface side and adjust the reflective mask blank to be flat. The conductive film on the back surface can be formed using known film deposition methods, such as sputtering methods including magnetron sputtering and ion beam sputtering, CVD, vacuum deposition, and electrolytic plating.

[0053] [Other membranes] The reflective mask blank of the present invention may have other films. Examples of other films include hard mask films. It is preferable that the hard mask film be positioned on the side opposite to the substrate side of the phase shift film. As the hard mask film, it is preferable to use a material that has high resistance to dry etching, such as a Ta-based film, a Cr-based film, or a Si-based film. In particular, it is preferable that the hard mask film contains Ta. Furthermore, it is also preferable that the hard mask film contains one or more elements selected from the group consisting of B, C, N, and O. Examples of Ta-based films include TaON. Examples of Cr-based films include materials containing Cr and one or more elements selected from the group consisting of Cr and O, N, C, and H. Specifically, examples include CrO and CrN. Examples of Si-based films include materials containing Si and one or more elements selected from the group consisting of Si and O, N, C, and H. Specifically, examples include SiO2, SiON, SiN, SiO, Si, SiC, SiCO, SiCN, and SiCON. By forming a hard mask film on a phase-shift film, dry etching can be performed even if the minimum line width of the phase-shift film pattern becomes smaller. Therefore, it is effective for miniaturizing the phase-shift film pattern.

[0054] Other types of films include anti-reflective coatings used when inspecting absorber film patterns using inspection light (for example, wavelengths of 193-248 nm). It is preferable that the anti-reflective coating be positioned on the opposite side of the phase-shift film from the substrate side.

[0055] <Method for manufacturing a reflective mask and the reflective mask itself> A reflective mask is obtained by patterning the phase-shift film present in 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.

[0056] 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 a phase shift film 18 in that order. A known method can be used to form the resist pattern 40. For example, a resist can be applied to the phase shift film 18 of the reflective mask blank, and then exposed and developed to form the resist pattern 40. The resist pattern 40 corresponds to a pattern formed on a wafer using a reflective mask. Subsequently, the phase-shift film 18 is etched and patterned using the resist pattern 40 in Figure 2(a) as a mask, and the resist pattern 40 is removed to obtain a laminate having the phase-shift 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 carried out 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).

[0057] Dry etching for forming the 18pt phase-shift film pattern can be performed using, for example, a Cl-based gas or a F-based gas. The resist pattern 40 or 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. Furthermore, if the reflective mask blank has a hard mask film as another film, the process of obtaining the reflective mask may include a step to remove the hard mask film. Also, the hard mask film may be removed simultaneously in the process of removing the resist pattern 40 or 41 as described above.

[0058] The reflective mask obtained by patterning a phase-shift film on the reflective mask blank of the present invention can be suitably applied as a reflective mask used for exposure with EUV light. [Examples]

[0059] The present invention will be described in more detail below based on examples. The materials, quantities, proportions, processing details, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following examples. Examples 1-7, described later, are examples of actual cases, while Examples 8-11 are comparative examples.

[0060] <Example 1 Reflective Mask Blank> The following describes the procedure for obtaining the reflective mask blank shown in Example 1, as a representative example. A SiO2-TiO2 glass substrate (6-inch (152 mm) square, 6.3 mm thick) was prepared as the substrate. This glass substrate has a thermal expansion coefficient of 0.02 × 10⁻¹⁰ at 20°C. -7 The temperature is / ℃, the Young's modulus is 67 GPa, the Poisson's ratio is 0.17, and the specific stiffness is 3.07 × 10⁻⁶. 7 m 2 / s 2 The quality assurance area of ​​the first main surface of the substrate had a mean square roughness (RMS) 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 / □.

[0061] 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 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 then depositing a Si film (thickness 4.5 nm) after the 40th Mo film was 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).

[0062] A Ru film (thickness 0.9 nm) was formed on a multilayer reflective film as a protective layer by ion beam sputtering, and then an Rh film (thickness 1.6 nm) was formed on the formed Ru film by ion beam sputtering.

[0063] A RuC film (phase-shift film) was deposited on the formed protective film using magnetron sputtering while supplying Ar gas. The deposition conditions were as follows: Targets: Ru target and C target Input power: Ru target 440W, C target 420W Chamber pressure: 0.3 Pa Film forming speed: 0.2nm / sec Film thickness: 35nm

[0064] Following the procedure described above, a reflective mask blank for Example 1 was obtained. The density and film thickness of the phase-shifted film on the obtained reflective mask blank were measured by XRR using the procedure described above.

[0065] The content of each element in the phase-shift film was measured using the following procedure. First, the resulting reflective mask blank was cut out to obtain a sample for measurement. The obtained sample was first analyzed by XPS. For the XPS analysis, an analytical instrument, "PHI 5000 VersaProbe," manufactured by ULVAC-PHI, Inc., was used. The sample was placed in the measuring holder with the phase-shift film side facing the measurement surface, and then loaded into the instrument. After loading the measurement holder into the apparatus, a portion of the phase-shifted film was removed from the outermost surface by 3 nm using an Ar ion beam. The sputtering rate during this removal was measured using a separately prepared sample. After removing the outermost surface of the phase-shift film, X-ray (monochromatic AlK) is used on the removed portion. α The sample was irradiated with a photoelectron beam, and the photoelectron extraction angle (the angle between the surface of the sample and the direction of the detector) was set to 45° for analysis. A neutralization gun was used during the analysis to suppress charge buildup. The binding energy was calibrated using Au4f, which was purified in an ultra-high vacuum. 7 / 2 The calculation was performed using an orbital binding energy of 83.96 eV. Spectra were obtained using the above apparatus, and the content of each element other than Ru and C was calculated from the area of ​​the peaks corresponding to each orbital of each element.

[0066] Furthermore, P0 / P1 in equation (I) above was calculated from the XPS spectrum obtained by the above method.

[0067] The Ru and C content of the phase-shift film was analyzed using XPS, as well as RBS and SIMS. For RBS measurement, a Kobe Steel HRBS500 was used. The RBS measurement was performed under the following conditions. Incident ion: 450 keV He + Scattering angle: 124° Incident angle: 29° Sample current: 60nA Irradiation amount: 50μC Furthermore, an ADEPT1010 from ULVAC-PHI was used for SIMS measurements. The SIMS measurements were performed under the following conditions. Primary ion species: Cs+ Primary acceleration voltage: 3.0kV

[0068] <Reflective mask blanks for Examples 2-11> Examples 2 to 11 were obtained in the same manner as the reflective mask blank of Example 1, except that the film deposition conditions for the phase-shift film were changed as shown below. The thickness and density of the phase-shift film, the content of each element, and the P0 / P1 value were measured in the same manner as the reflective mask blank of Example 1.

[0069] • Fabrication conditions for phase-shifted film on reflective mask blank in Example 2 Input power: Ru target 120W, C target 460W Film forming speed: 0.07nm / sec • Fabrication conditions for the phase-shifted film on the reflective mask blank in Example 3 Input power: Ru target 640W, C target 270W Introduced gas: Mixture of N2 and Ar gas (N2:Ar = 10:90 (volume ratio)) Film forming speed: 0.2nm / sec • Fabrication conditions for the phase-shifted film on the reflective mask blank in Example 4 Targets: Ru target and Cr3C2 target Input power: Ru target 520W, Cr3C2 target 490W Film forming speed: 0.3nm / sec • Fabrication conditions for the phase-shifted film on the reflective mask blank in Example 5 Targets: Ru target and Cr target Input power: Ru target 260W, Cr target 250W Introduced gas: A mixture of methane and Ar gas (methane:Ar = 4:96 (volume ratio)) Film forming speed: 0.1nm / sec • Fabrication conditions for the phase-shifted film on the reflective mask blank in Example 6 Targets: Ru target and Cr3C2 target Input power: Ru target 520W, Cr3C2 target 490W Introduced gas: Mixture of N2 and Ar gas (N2:Ar = 10:90 (volume ratio)) Film forming speed: 0.2nm / sec • Fabrication conditions for the phase-shifted film on the reflective mask blank in Example 7 Targets: Ru target, Re target, and C target Input power: Ru target 440W, Re target 120W, C target 440W Film forming speed: 0.2nm / sec • Fabrication conditions for the phase-shifted film of the reflective mask blank in Example 8 Input power: Ru target 150W, C target 530W Film forming speed: 0.06nm / sec • Fabrication conditions for the phase-shifted film of the reflective mask blank in Example 9 Targets: Ru target and C target Input power: Ru target 140W, C target 520W Chamber pressure: 1.0 Pa Film forming speed: 0.06nm / sec • Fabrication conditions for phase-shifted film on reflective mask blank in Example 10 Target: Ru target Input power: Ru target 500W Introduced gas: A mixed gas of N2, O2, and Ar (N2:O2:Ar = 20:10:70 (volume ratio)) Film forming speed: 0.08nm / sec • Fabrication conditions for phase-shifted film on reflective mask blank in Example 11 Target: C target Input power: C target 500W Film forming speed: 0.03nm / sec

[0070] Furthermore, in the reflective mask blank of Example 5, which was deposited using methane gas, H was detected in the phase-shifted film by SIMS analysis.

[0071] <Rating> [Hydrogen resistance] The hydrogen resistance of the phase-shift film was evaluated by irradiating it with hydrogen plasma and comparing the density and film thickness of the phase-shift film before and after irradiation. The smaller the rate of change in density and film thickness, the better the hydrogen resistance of the phase-shift film. In practical terms, a rate of change in density and film thickness of ±1.0% or less is preferable. The rate of change in density and film thickness was calculated using the following formulas, and the density and film thickness of the phase-shift film before and after hydrogen plasma irradiation were measured using XRR. (Percentage change in density) = {(Density after irradiation) - (Density before irradiation)} / (Density before irradiation) (Percentage change in film thickness) = {(Film thickness after irradiation) - (Film thickness before irradiation)} / (Film thickness before irradiation)

[0072] [Crystalline] The crystallinity of the phase-shift film was evaluated using the crystallite size calculated from the diffraction chart obtained by XRD using the method described above. In the examples, in order to exclude the overlap of diffraction lines from the Mo layer of the multilayer reflective film from the crystallinity evaluation, the crystallinity of the phase-shift film in each example was evaluated using a sample obtained by depositing the phase-shift film on a Si wafer under the same conditions as described above. Here, the crystallinity of the phase-shift film deposited on the Si wafer corresponds well to the crystallinity of the phase-shift film in the reflective mask blank obtained by the above procedure. In these examples, a Si wafer was used as the substrate, but when evaluating crystallinity, an amorphous substrate such as glass that does not produce diffraction lines in X-ray diffraction may be used. In practical terms, phase-shift films are preferably amorphous or have a crystallite size of 7.0 nm or less. In the table below, if no clear diffraction peaks are observed in the diffraction chart, it will be described as "amorphous." The diffraction chart was obtained under the following conditions. Device name: Rigaku MiniFlexII Incident X-ray: CuKα ray

[0073] <Result> Table 1 shows the composition of the phase-shift film of the reflective mask blanks for each example, the P0 / P1 values, and the refractive index n and extinction coefficient k (EUV optical constants) for 13.5 nm EUV light. Table 1 also shows the evaluation results of the reflective mask blanks for each example. The refractive index n and extinction coefficient k for EUV light were measured using the method described above.

[0074] [Table 1]

[0075] As shown in Table 1, the results from Examples 1 to 7 confirmed that the phase-shift film of the reflective mask blank of the present invention has low crystallinity and excellent hydrogen resistance. On the other hand, the results from Examples 8 and 9 showed that the density of the phase-shift film was 8.0 g / cm³. 3 When the value was less than [value], hydrogen resistance was low. Also, from the results of Examples 10 and 11, when the phase-shift film did not contain either Ru or C, hydrogen resistance was low. From a comparison of Examples 3-6 with Examples 1, 2, and 7, it was confirmed that when the C content in the phase-shift film is 4.0-17.0 atomic% relative to the total atoms of the phase-shift film, the film thickness change is small and hydrogen resistance is superior. [Explanation of symbols]

[0076] 10 Reflective Mask Blanks 12 circuit boards 14 Multilayer reflective film 16 Protective film 18 Phase-shift film 18pt Phase-Shift Film Pattern 40,41 Resist Pattern

Claims

1. circuit board and A multilayer reflective film that reflects EUV light, Protective film and, A reflective mask blank having, in this order, a phase-shifting film that shifts the phase of EUV light, The phase-shift film comprises at least ruthenium and carbon, The density of the phase-shift film, calculated by X-ray reflectivity, is 8.0 g / cm³. ３ That concludes the description of the reflective mask blank.

2. The reflective mask blank according to claim 1, wherein the carbon content in the phase-shift film is 48.0 atomic% or less relative to the total atoms of the phase-shift film.

3. The reflective mask blank according to claim 1 or 2, wherein the carbon content in the phase-shift film is 4.0 to 30.0 atomic percent relative to the total atoms of the phase-shift film.

4. The reflective mask blank according to claim 1 or 2, wherein, in the spectrum obtained when the phase-shift film is analyzed by X-ray photoelectron spectroscopy, P0 is the maximum intensity of the peak at a binding energy of 278 to 282 eV, and P1 is the maximum intensity of the peak at a binding energy of 282 to 286 eV, the following equation (I) is satisfied. Equation (I) P0 / P1 ≥ 1.50

5. The reflective mask blank according to claim 1 or 2, wherein the phase-shift film further comprises at least one element of hydrogen, boron, nitrogen, and oxygen.

6. The reflective mask blank according to claim 5, wherein the total content of hydrogen and nitrogen contained in the phase-shift film is 10 atomic percent or less relative to the total atoms of the phase-shift film.

7. The reflective mask blank according to claim 1 or 2, wherein the phase-shift film further comprises one or more elements selected from the group consisting of chromium, zirconium, niobium, molybdenum, hafnium, tantalum, tungsten, rhenium, osmium, and iridium.

8. The reflective mask blank according to claim 7, wherein the total content of one or more elements selected from the group consisting of chromium, zirconium, niobium, molybdenum, hafnium, tantalum, tungsten, rhenium, osmium, and iridium in the phase-shift film is 50 atomic percent or less relative to the total atoms of the phase-shift film.

9. The reflective mask blank according to claim 1 or 2, wherein the refractive index of the phase-shift film for EUV light at a wavelength of 13.5 nm is 0.920 or less.

10. The reflective mask blank according to claim 1 or 2, wherein the extinction coefficient of the phase-shift film for EUV light at a wavelength of 13.5 nm is 0.0130 or greater.

11. The manufacturing method according to claim 1 or 2, wherein the thickness of the phase-shift film is 60 nm or less.

12. The reflective mask blank according to claim 1 or 2, further comprising a hard mask film on the side of the phase-shift film opposite to the substrate side.

13. The reflective mask blank according to claim 12, wherein the hard mask film contains tantalum.

14. The reflective mask blank according to claim 12, wherein the hard mask film further comprises one or more elements selected from the group consisting of boron, carbon, nitrogen, and oxygen.

15. The reflective mask blank according to claim 1 or 2, further comprising a buffer film between the phase-shift film and the protective film.

16. The reflective mask blank according to claim 15, wherein the buffer film contains one or more elements selected from the group consisting of tantalum and chromium.

17. The reflective mask blank according to claim 16, wherein the buffer film further comprises one or more elements selected from the group consisting of boron, carbon, nitrogen, and oxygen.

18. The reflective mask blank according to claim 15, wherein the refractive index of the buffer film with respect to EUV light at a wavelength of 13.5 nm is 0.920 to 0.970, and the extinction coefficient of the buffer film with respect to EUV light at a wavelength of 13.5 nm is 0.0150 to 0.0400.

19. The reflective mask blank according to claim 15, wherein the thickness of the buffer film is 10 nm or less.

20. A method for manufacturing a reflective mask blank according to claim 1 or 2, A method for manufacturing a reflective mask blank, comprising forming the phase-shift film by sputtering, and using elemental carbon or a metal carbide as at least one of the targets for the sputtering method.

21. A method for manufacturing a reflective mask blank according to claim 1 or 2, A method for manufacturing a reflective mask blank, comprising forming the phase-shift film by a reactive sputtering method, and using a gas containing a compound gas containing carbon atoms as the gas used in the reactive sputtering method.

22. The method for producing a reflective mask blank according to claim 21, wherein the gas of the carbon-carbon compound includes one or more selected from the group consisting of methane gas, ethane gas, ethylene gas, acetylene gas, and carbon dioxide.

23. A reflective mask having a phase-shift film pattern formed by patterning the phase-shift film of the reflective mask blank according to claim 1 or 2.

24. A method for manufacturing a reflective mask, comprising the step of patterning the phase-shift film of the reflective mask blank according to claim 1 or 2.

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