Reflective mask blank for EUV lithography and substrate with conductive film

Abstract

To provide an EUV mask blank that transmits light in the range of 1000 to 1100 nm and 600 to 700 nm when light is incident from the conductive film side, and suppresses the transmission of light in the range of 400 to 500 nm, and has excellent fixing force when fixed to an exposure device.SOLUTION: There is provided a reflection type mask blank for EUV lithography that has a substrate, a conductive film arranged on a rear side of the substrate, a reflective layer arranged on a front side of the substrate, and an absorption layer arranged on the reflective layer, wherein the conductive film contains at least one of nitrogen (N) and boron (B), the total content of N and B contained in the conductive film is more than 0 at% and 65 at% or less, and a refractive index and an extinction coefficient in the wavelengths of 1000 to 1100 nm, 600 to 700 nm, and 400 to 500 nm of the conductive film, as well as the thickness t and resistivity of the conductive film are within a specific range.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a reflective mask blank for EUV (Extreme Ultra Violet) lithography used in semiconductor manufacturing and the like (hereinafter, referred to as "EUV mask blank" in this specification), and a substrate with a conductive film used for manufacturing the EUV mask blank.

Background Art

[0002] Conventionally, in the semiconductor industry, as a fine pattern transfer technique necessary for forming an integrated circuit composed of fine patterns on an Si substrate or the like, a photolithography method using visible light or ultraviolet light has been used. However, while the miniaturization of semiconductor devices has been accelerating, the limits of the conventional photolithography method have been approached. In the case of the photolithography method, the resolution limit of the pattern is about 1 / 2 of the exposure wavelength. Even when the immersion method is used, it is said to be about 1 / 4 of the exposure wavelength, and even when the immersion method of an ArF laser (193 nm) is used, about 20 to 30 nm is expected to be the limit. Therefore, as an exposure technique after 20 to 30 nm, EUV lithography, an exposure technique using EUV light with a shorter wavelength than the ArF laser, is regarded as promising. In this specification, EUV light refers to light rays with wavelengths in the soft X-ray region or the vacuum ultraviolet region. Specifically, it refers to light rays with a wavelength of about 10 to 20 nm, particularly about 13.5 nm ± 0.3 nm.

[0003] EUV light is easily absorbed by all substances, and the refractive index of substances at this wavelength is close to 1. Therefore, a refractive optical system such as conventional photolithography using visible light or ultraviolet light cannot be used. For this reason, in EUV lithography, a reflective optical system, that is, a reflective photomask and a mirror, are used.

[0004] On the other hand, apart from the shortening of the wavelength of light, a resolution improvement technique using a phase shift mask has been proposed. A phase shift mask gives a 180-degree phase difference to the light transmitted through the transmissive portions by making the transmissive portions of the mask pattern have a different material or shape from adjacent transmissive portions. Therefore, in the region between both transmissive portions, the transmitted diffracted lights with a 180-degree phase difference cancel each other out, the light intensity becomes extremely small, the mask contrast is improved, and as a result, the depth of focus during transfer is expanded and the transfer accuracy is improved. Although 180 degrees is theoretically the best for the phase difference, a resolution improvement effect can be sufficiently obtained if it is substantially about 175 to 185 degrees.

[0005] A mask blank is a laminate before patterning used for manufacturing a photomask. In the case of an EUV mask blank, it has a structure in which a reflective layer that reflects EUV light and an absorption layer that absorbs EUV light are formed in this order on a substrate such as made of glass.

[0006] As the reflective layer, a multilayer reflective film with an increased light reflectance when the layer surface is irradiated with EUV light is usually used by alternately laminating a low refractive index layer with a low refractive index for EUV light and a high refractive index layer with a high refractive index for EUV light. As the low refractive index layer of the multilayer reflective film, a molybdenum (Mo) layer is usually used, and as the high refractive index layer, a silicon (Si) layer is usually used.

[0007] For the absorption layer, a material with a high absorption coefficient for EUV light, specifically, for example, a material mainly composed of chromium (Cr) or tantalum (Ta) is used.

[0008] The multilayer reflective film and the absorption layer are formed on the optical surface of the glass substrate using an ion beam sputtering method or a magnetron sputtering method. When forming the multilayer reflective film and the absorption layer, the glass substrate is held by a support means. As the support means for the glass substrate, there are a mechanical chuck and an electrostatic chuck, but due to the problem of dust generation, the electrostatic chuck is preferably used. Also, during the mask patterning process or when handling the mask during exposure, the electrostatic chuck is used as the support means for the glass substrate.

[0009] An electrostatic chuck is a technology that has been conventionally used as a support means for a silicon (Si) wafer in the manufacturing process of semiconductor devices. Therefore, in the case of a substrate with low dielectric constant and conductivity, such as a glass substrate, in order to obtain a chucking force comparable to that of an Si wafer, it is necessary to apply a high voltage, which poses a risk of dielectric breakdown.

[0010] Therefore, in order to promote the electrostatic chucking of the substrate, a conductive film is formed on the side opposite to the multilayer reflective film with the substrate sandwiched therebetween.

[0011] In an EUV mask and an EUV mask blank used therefor, deformation of the substrate caused by internal stress in the multilayer reflective film as a reflective layer or in the absorption layer may be a problem. A technique of locally irradiating a pulsed laser beam from the back side of the EUV mask or EUV mask blank to locally heat the glass substrate to improve the deformation of the substrate due to internal stress in the multilayer reflective film and absorption layer is being newly introduced.

[0012] In order to apply the above technique, Patent Document 1 provides an EUV mask blank having a conductive film formed on the back surface with high light transmittance in the wavelength range of 400 to 800 nm.

Prior Art Documents

Patent Documents

[0013]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0014] On the other hand, an Ar laser with a wavelength of 488 nm is used for defect inspection after the formation of the conductive film. If the conductive film has high light transmittance in this wavelength range, defect inspection cannot be carried out. Therefore, the conductive film is required to have low light transmittance in this wavelength range.

[0015] When an Ar laser with a wavelength of 488 nm is used for defect inspection after forming the conductive film, in order to locally irradiate the laser light and improve the deformation of the substrate due to internal stress in the multilayer reflective film or the absorption layer, a Nd:YAG laser with a wavelength of 1064 nm or a He:Ne laser with a wavelength of 632 nm can be used. When using these lasers, the conductive film is required to have a high light transmittance in these wavelength ranges.

[0016] In addition, the EUV mask blank is applied to the exposure apparatus after patterning the absorption layer. At this time, the EUV mask blank with the conductive film formed may have insufficient fixing force when fixed to the exposure apparatus. In order to prevent such insufficient fixing force, it is effective to reduce the resistivity of the conductive film.

[0017] In order to solve the above-mentioned problems of the prior art, the present invention provides an EUV mask blank that sufficiently transmits light in the range of wavelengths of 1000 to 1100 nm and in the range of wavelengths of 600 to 700 nm when incident from the conductive film side, suppresses the transmission of light in the range of wavelengths of 400 to 500 nm, and has excellent fixing force when fixed to the exposure apparatus, and a substrate with a conductive film used for manufacturing the EUV mask blank.

Means for Solving the Problems

[0018] The present inventors have found that the above problems can be solved by the following configuration. (1) A substrate, A conductive film disposed on the back surface side of the substrate, A reflective layer disposed on the front surface side of the substrate that reflects EUV light, An EUV lithography reflective mask blank having an absorption layer disposed on the reflective layer that absorbs EUV light, The conductive film contains at least one of nitrogen (N) and boron (B), The total content of N and B contained in the conductive film is more than 0 at% and 65 at% or less, The refractive index n of the conductive film at a wavelength of 1000 to 1100 nm λ1000-1100nmis 5.300 or less, and the attenuation coefficient k λ1000-1100nm is 5.200 or less, and The refractive index n of the conductive film at a wavelength of 600 to 700 nm λ600-700nm is 4.300 or less, and the attenuation coefficient k λ600-700nm is 4.500 or less, and The refractive index n of the conductive film at a wavelength of 400 to 500 nm λ400-500nm is 2.500 or more, and the attenuation coefficient k λ400-500nm is 0.440 or more, and The film thickness t of the conductive film is 20 to 350 nm, and The resistivity of the conductive film is 3.5 mΩ·cm or less. A reflective mask blank for EUV lithography. (2) A substrate, and A conductive film disposed on the back side of the substrate, and A reflective layer disposed on the front side of the substrate that reflects EUV light, and A reflective mask blank for EUV lithography having an absorption layer disposed on the reflective layer that absorbs EUV light, The conductive film contains at least one of nitrogen (N) and boron (B), The total content of N and B contained in the conductive film is more than 0 at% and 65 at% or less, The refractive index n of the conductive film at a wavelength of 1000 to 1100 nm λ1000-1100nm is 5.300 or less, and the attenuation coefficient k λ1000-1100nm is 5.200 or less, and The refractive index n of the conductive film at a wavelength of 600 to 700 nm λ600-700nm is 4.300 or less, and the attenuation coefficient k λ600-700nm is 4.500 or less, and The refractive index n of the conductive film at a wavelength of 480 to 500 nm λ480-500nm is 2.500 or more, and the attenuation coefficient k λ480-500nm is 0.440 or more, and The film thickness t of the conductive film is 20 to 350 nm, and The resistivity of the conductive film is 3.5 mΩ·cm or less. A reflective mask blank for EUV lithography. (3) The reflective mask blank for EUV lithography according to (1) or (2), wherein the conductive film contains at least one of tantalum (Ta) and chromium (Cr). (4) The reflective mask blank for EUV lithography according to (1) or (2), wherein the conductive film contains Ta and N. (5) The reflective mask blank for EUV lithography according to (4), wherein the conductive film contains N in an amount greater than 0 at% and less than or equal to 65 at%. (6) The reflective mask blank for EUV lithography according to (1) or (2), wherein the conductive film contains Ta and B. (7) The reflective mask blank for EUV lithography according to (6), wherein the conductive film contains B in an amount greater than 0 at% and less than or equal to 35 at%. (8) The reflective mask blank for EUV lithography according to (1) or (2), wherein the resistivity of the conductive film is 0.050 mΩ·cm or more and 3.5 mΩ·cm or less. (9) The reflective mask blank for EUV lithography according to (1) or (2), wherein the conductive film contains Ta, and in the diffraction peaks derived from the conductive film observed by the out-of-plane XRD method, the full width at half maximum (FWHM) of the diffraction peak attributed to the bcc (110) plane of Ta is 1.5 to 4.0°. (10) The reflective mask blank for EUV lithography according to (1) or (2), wherein the light transmittance of the conductive film at a wavelength of 1000 to 1100 nm is 1.0% or more, the light transmittance at a wavelength of 600 to 700 nm is 1.0% or more, and the light transmittance at a wavelength of 400 to 500 nm is 1.0% or less. (11) The reflective mask blank for EUV lithography according to (1) or (2), wherein the sheet resistance value of the conductive film is 250 Ω / □ or less. (12) The reflective mask blank for EUV lithography according to (1) or (2), wherein the surface hardness of the conductive film is 10.0 GPa or more. (13) An upper layer is further provided on the conductive film. The upper layer contains chromium (Cr) and at least one element selected from the group consisting of nitrogen (N) and oxygen (O), and is the reflective mask blank for EUV lithography according to (1) or (2). (14) The surface roughness (Rq) of the conductive film is 0.600 nm or less, and is the reflective mask blank for EUV lithography according to (1) or (2). (15) A substrate with a conductive film, having a conductive film on the substrate, wherein the conductive film contains at least one of nitrogen (N) and boron (B), the total content of N and B contained in the conductive film is more than 0 at% and 65 at% or less, the refractive index n of the conductive film at a wavelength of 1000 to 1100 nm λ1000-1100nm is 5.300 or less, and the extinction coefficient k λ1000-1100nm is 5.200 or less, the refractive index n of the conductive film at a wavelength of 600 to 700 nm λ600-700nm is 4.300 or less, and the extinction coefficient k λ600-700nm is 4.500 or less, the refractive index n of the conductive film at a wavelength of 400 to 500 nm λ400-500nm is 2.500 or more, and the extinction coefficient k λ400-500nm is 0.440 or more, the film thickness t of the conductive film is 20 to 350 nm, The resistivity of the conductive film is 3.5 mΩ·cm or less, and it is a substrate with a conductive film. (16) A substrate with a conductive film, having a conductive film on the substrate, wherein the conductive film contains at least one of nitrogen (N) and boron (B), the total content of N and B contained in the conductive film is more than 0 at% and 65 at% or less, the refractive index n of the conductive film at a wavelength of 1000 to 1100 nm λ1000-1100nm is 5.300 or less, and the extinction coefficient k λ1000-1100nm is 5.200 or less, the refractive index n of the conductive film at a wavelength of 600 to 700 nm λ600-700nm is 4.300 or less, and the extinction coefficient k λ600-700nmis 4.500 or less, the refractive index n of the conductive film at a wavelength of 480 to 500 nm λ480-500nm is 2.500 or more, and the extinction coefficient k λ480-500nm is 0.440 or more, the film thickness t of the conductive film is 20 to 350 nm, A substrate with a conductive film, wherein the resistivity of the conductive film is 3.5 mΩ·cm or less. (17) The substrate with a conductive film according to (15) or (16), wherein the conductive film contains at least one of tantalum (Ta) and chromium (Cr). (18) The substrate with a conductive film according to (15) or (16), wherein the conductive film contains Ta and N. (19) The substrate with a conductive film according to (18), wherein the conductive film contains N in an amount of more than 0 at% and 65 at% or less. (20) The substrate with a conductive film according to (15) or (16), wherein the conductive film contains Ta and B. (21) The substrate with a conductive film according to (20), wherein the conductive film contains B in an amount of more than 0 at% and 35 at% or less. (22) The substrate with a conductive film according to (15) or (16), wherein the resistivity of the conductive film is 0.050 mΩ·cm or more and 3.5 mΩ·cm or less. (23) The substrate with a conductive film according to (15) or (16), wherein the conductive film contains Ta, and among the diffraction peaks derived from the conductive film observed by the out-of-plane XRD method, the full width at half maximum FWHM of the diffraction peak attributed to the bcc(110) plane of Ta is 1.5 to 4.0°. (24) The substrate with a conductive film according to (15) or (16), wherein the light transmittance of the conductive film at a wavelength of 1000 to 1100 nm is 1.0% or more, the light transmittance at a wavelength of 600 to 700 nm is 1.0% or more, and the light transmittance at a wavelength of 400 to 500 nm is 1.0% or less. (25) The substrate with a conductive film according to (15) or (16), wherein the sheet resistance value of the conductive film is 250 Ω / □ or less. (26) The substrate with a conductive film according to (15) or (16), wherein the surface hardness of the conductive film is 10.0 GPa or more. (27) A further upper layer is provided on the conductive film. The upper layer contains chromium (Cr) and at least one element selected from the group consisting of nitrogen (N) and oxygen (O), and the substrate with a conductive film according to (15) or (16). (28) The surface roughness (Rq) of the conductive film is 0.600 nm or less, and the substrate with a conductive film according to (15) or (16). [Advantages of the Invention]

[0019] The EUV mask blank of the embodiment of the present invention (hereinafter, also referred to as the EUV mask blank of the present embodiment) transmits light in the wavelength range of 1000 to 1100 nm and light in the wavelength range of 600 to 700 nm when incident from the conductive film side, and suppresses the transmission of light in the wavelength range of 400 to 500 nm. Further, since the resistivity of the conductive film is sufficiently low, excellent fixing force can be obtained when fixed to the exposure apparatus. [Brief Description of the Drawings]

[0020]

Figure 1

[0021] The first aspect of the EUV mask blank of the present embodiment is a reflective mask blank for EUV lithography having a substrate, a conductive film disposed on the back surface side of the substrate, a reflective layer disposed on the front surface side of the substrate and reflecting EUV light, and an absorption layer disposed on the reflective layer and absorbing EUV light, wherein the conductive film contains at least one of nitrogen (N) and boron (B), the total content of N and B contained in the conductive film is more than 0 at% and 65 at% or less, the refractive index n of the conductive film at a wavelength of 1000 to 1100 nm λ1000-1100nm is 5.300 or less, and the extinction coefficient k λ1000-1100nm is 5.200 or less, the refractive index n of the conductive film at a wavelength of 600 to 700 nm λ600-700nm is 4.300 or less, and the extinction coefficient k λ600-700nmis 4.500 or less, and the refractive index n of the conductive film at a wavelength of 400 to 500 nm λ400-500nm is 2.500 or more, and the attenuation coefficient k λ400-500nm is 0.440 or more, the film thickness t of the conductive film is 20 to 350 nm, and the resistivity of the conductive film is 3.5 mΩ·cm or less.

[0022] A second aspect of the EUV mask blank according to an embodiment of the present invention is a reflective mask blank for EUV lithography, having a substrate, a conductive film disposed on the back surface side of the substrate, a reflective layer disposed on the front surface side of the substrate and reflecting EUV light, and an absorption layer disposed on the reflective layer and absorbing EUV light, wherein the conductive film contains at least one of nitrogen (N) and boron (B), the total content of N and B contained in the conductive film is more than 0 at%, 65 at% or less, and the refractive index n of the conductive film at a wavelength of 1000 to 1100 nm λ1000-1100nm is 5.300 or less, and the attenuation coefficient k λ1000-1100nm is 5.200 or less, and the refractive index n of the conductive film at a wavelength of 600 to 700 nm λ600-700nm is 4.300 or less, and the attenuation coefficient k λ600-700nm is 4.500 or less, and the refractive index n of the conductive film at a wavelength of 480 to 500 nm λ480-500nm is 2.500 or more, and the attenuation coefficient k λ480-500nm is 0.440 or more, the film thickness t of the conductive film is 20 to 350 nm, and the resistivity of the conductive film is 3.5 mΩ·cm or less.

[0023] Hereinafter, the EUV mask blank of the present embodiment will be described with reference to the drawings. Note that the description of the EUV mask blank of the present embodiment applies to both the first aspect and the second aspect of the EUV mask blank of the present embodiment unless otherwise specified.

[0024] FIG. 1 is a schematic cross-sectional view showing one embodiment of an EUV mask blank of the present invention. In the EUV mask blank 10 shown in FIG. 1, a reflective layer 13 that reflects EUV light and an absorption layer 14 that absorbs EUV light are formed in this order on one surface (the upper surface of the substrate 11 in the figure) of the substrate 11. A conductive film 12 is formed on the other surface (the lower surface of the substrate 11 in the figure) of the substrate 11. Hereinafter, in this specification, the surface of the substrate 11 on which the reflective layer 13 and the absorption layer 14 are disposed is defined as the front surface of the substrate 11, and the surface of the substrate 11 on which the conductive film 12 is disposed is defined as the back surface of the substrate 11.

[0025] Hereinafter, each component of the EUV mask blank 10 of the present embodiment will be described.

[0026] The substrate 11 satisfies the characteristics as a substrate for an EUV mask blank. Therefore, the substrate 11 has a low coefficient of thermal expansion and is excellent in smoothness, flatness, and resistance to a cleaning liquid used for cleaning the mask blank or a photomask after pattern formation. Here, the low coefficient of thermal expansion specifically means that the coefficient of thermal expansion at 20 ° C is preferably 0 ± 0.05 × 10 -7 / °C, and more preferably 0 ± 0.03 × 10 -7 / °C. Specifically, as the substrate 11, glass having a low coefficient of thermal expansion, such as SiO2-TiO2-based glass, is used, but it is not limited thereto, and a crystallized glass in which β-quartz solid solution is precipitated, quartz glass, silicon, a metal, or the like can also be used as the substrate.

[0027] It is preferable that the substrate 11 has a smooth surface with a surface roughness (Rq) of 0.15 nm or less and a flatness of 100 nm or less because high reflectivity and transfer accuracy can be obtained in the photomask after pattern formation.

[0028] The size, thickness, etc. of the substrate 11 are appropriately determined according to the design value of the mask, etc. In the examples shown later, SiO2-TiO2-based glass with an outer shape of 6 inches (152 mm) square and a thickness of 0.25 inches (6.3 mm) was used.

[0029] It is preferable that there are no defects on the surface of the substrate 11. However, even if there are defects, as long as phase defects are not caused by concave defects and / or convex defects. Specifically, it is preferable that the depth of the concave defect and the height of the convex defect are 2 nm or less, and the full width at half maximum of these concave and convex defects is 60 nm or less. The full width at half maximum of the concave defect refers to the width at the position of half the depth of the concave defect. The full width at half maximum of the convex defect refers to the width at the position of half the height of the convex defect.

[0030] The conductive film 12 has a refractive index n λ1000-1100nm of 5.300 or less at a wavelength of 1000 to 1100 nm, and an extinction coefficient k λ1000-1100nm of 5.200 or less.

[0031] The refractive index n λ1000-1100nm and the extinction coefficient k λ1000-1100nm being within the above range, the conductive film 12 has a high light transmittance at a wavelength of 1000 to 1100 nm, so it is preferable when using a Nd:YAG laser with a wavelength of 1064 nm to improve the deformation of the substrate.

[0032] The light transmittance of the conductive film 12 at a wavelength of 1000 to 1100 nm is preferably 1.0% or more, more preferably 2.0% or more, and even more preferably 2.5% or more. The upper limit of the light transmittance of the conductive film 12 at a wavelength of 1000 to 1100 nm is not particularly limited, but is, for example, 3.5% or less.

[0033] The refractive index n of the conductive film 12 λ1000-1100nm is preferably 5.200 or less. The refractive index n of the conductive film 12 λ1000-1100nm has no particular lower limit, but is, for example, 4.000 or more.

[0034] The extinction coefficient k of the conductive film 12 λ1000-1100nm is preferably 5.100 or less. The extinction coefficient k of the conductive film 12 λ1000-1100nm has no particular lower limit, but is, for example, 3.000 or more.

[0035] The conductive film 12 has a refractive index n λ600-700nm of 4.300 or less at a wavelength of 600 to 700 nm, and an extinction coefficient kλ600-700nm is 4.500 or less.

[0036] Refractive index n λ600-700nm and extinction coefficient k λ600-700nm When they are within the above ranges, the conductive film 12 has a high light transmittance at wavelengths of 600 to 700 nm, and thus is preferable when using a He:Ne laser with a wavelength of 632 nm to improve the deformation of the substrate.

[0037] The light transmittance of the conductive film 12 at wavelengths of 600 to 700 nm is preferably 1.0% or more, more preferably 1.5% or more. The upper limit of the light transmittance of the conductive film 12 at wavelengths of 600 to 700 nm is not particularly limited, but is, for example, 2.5% or less.

[0038] The refractive index n of the conductive film 12 λ600-700nm is preferably 4.200 or less. The refractive index n of the conductive film 12 λ600-700nm has no particular lower limit, but is, for example, 3.100 or more.

[0039] The extinction coefficient k of the conductive film 12 λ600-700nm is preferably 4.400 or less. The extinction coefficient k of the conductive film 12 λ600-700nm has no particular upper limit, but is, for example, 2.500 or more.

[0040] In the first aspect of the EUV mask blank of the present embodiment, the conductive film 12 has a refractive index n at wavelengths of 400 to 500 nm λ400-500nm of 2.500 or more and an extinction coefficient k λ400-500nm of 0.440 or more. In the second aspect of the EUV mask blank of the present embodiment, the conductive film 12 preferably has a refractive index n at wavelengths of 400 to 500 nm λ400-500nm of 2.500 or more and preferably an extinction coefficient k λ400-500nm of 0.440 or more.

[0041] Refractive index n λ400-500nm and extinction coefficient k λ400-500nmWhen it is within the above range, since the conductive film 12 has a low light transmittance for light with wavelengths of 400 to 500 nm, it is preferable when using an Ar laser with a wavelength of 488 nm for defect inspection.

[0042] The light transmittance of the conductive film 12 for light with wavelengths of 400 to 500 nm is preferably 1.0% or less, and more preferably less than 1.0%. The lower limit of the light transmittance of the conductive film 12 for light with wavelengths of 400 to 500 nm is not particularly limited, but is, for example, 0.7% or more.

[0043] The refractive index n of the conductive film 12 λ400-500nm is preferably 2.600 or more, more preferably 2.650 or more, and even more preferably 2.700 or more. The refractive index n of the conductive film 12 λ400-500nm has no particular upper limit, but is, for example, 3.300 or less.

[0044] The attenuation coefficient k of the conductive film 12 λ400-500nm is preferably 0.500 or more, more preferably 1.000 or more, even more preferably 1.500 or more, and particularly preferably 1.800 or more. The attenuation coefficient k of the conductive film 12 λ400-500nm has no particular upper limit, but is, for example, 4.300 or less.

[0045] In the first aspect of the EUV mask blank of the present embodiment, the conductive film 12 preferably has a refractive index n λ480-500nm of 2.500 or more at wavelengths of 480 to 500 nm, and an attenuation coefficient k λ480-500nm of 0.440 or more. In the second aspect of the EUV mask blank of the present embodiment, the conductive film 12 has a refractive index n λ480-500nm of 2.500 or more at wavelengths of 480 to 500 nm, and an attenuation coefficient k λ480-500nm of 0.440 or more.

[0046] The refractive index n of the conductive film 12 λ480-500nm is preferably 2.600 or more, more preferably 2.700 or more, and even more preferably 2.800 or more. The refractive index n of the conductive film 12 λ480-500nm has no particular upper limit, but is, for example, 3.300 or less.

[0047] Attenuation coefficient k of the conductive film 12 λ480-500nm is preferably 0.500 or more, more preferably 1.000 or more, still more preferably 1.500 or more, particularly preferably 2.000 or more, and most preferably 2.200 or more. The attenuation coefficient k of the conductive film 12 λ480-500nm has no particular upper limit, but is, for example, 4.300 or less.

[0048] The conductive film 12 has a film thickness t of 20 to 350 nm. When the film thickness t is 20 nm or more, the light transmittance at wavelengths of 400 to 500 nm can be sufficiently reduced. When the film thickness t exceeds 350 nm, even if the refractive index n λ1000-1100nm and the attenuation coefficient k λ1000-1100nm satisfy the above ranges, the light transmittance at wavelengths of 1000 to 1100 nm will not be sufficiently high. Also, even if the refractive index n λ600-700nm and the attenuation coefficient k λ600-700nm satisfy the above ranges, the light transmittance at wavelengths of 600 to 700 nm will not be sufficiently high.

[0049] The film thickness t of the conductive film 12 is preferably 20 nm or more, more preferably 25 nm or more, and still more preferably 30 nm or more. The film thickness t of the conductive film 12 is preferably 300 nm or less, more preferably 200 nm or less, and still more preferably 100 nm or less.

[0050] The refractive index n λ1000-1100nm , the refractive index n λ600-700nm and the refractive index n λ400-500nm satisfy the above ranges, and the attenuation coefficient k λ1000-1100nm , the attenuation coefficient k λ600-700nm and the attenuation coefficient k λ400-500nm The conductive film 12 that satisfies the above ranges contains at least one of nitrogen (N) and boron (B). Also, the refractive index n λ1000-1100nm , the refractive index n λ600-700nm and the refractive index n λ480-500nm satisfy the above ranges, and the attenuation coefficient k λ1000-1100nm , the attenuation coefficient k λ600-700nm and the attenuation coefficient k λ480-500nmThe conductive film 12 that satisfies the above range contains at least one of nitrogen (N) and boron (B).

[0051] The conductive film 12 contains at least one of nitrogen (N) and boron (B). That is, the total content of N and B contained in the conductive film 12 is more than 0 at%. Thereby, the conductive film 12 can be amorphized. The total content of N and B is preferably 2 at% or more, more preferably 5 at% or more, and still more preferably 10 at% or more.

[0052] Also, from the viewpoint of the resistivity of the conductive film, the total content of N and B is 65 at% or less, preferably 60 at% or less, and more preferably 40 at% or less. That is, the total content of N and B is more than 0 at% and 65 at% or less.

[0053] From the same viewpoint as above, when N is contained in the conductive film 12, the content of N is preferably more than 0 at%, more preferably 2 at% or more, still more preferably 5 at% or more, and even more preferably 10 at% or more. Also, when N is contained in the conductive film 12, the content of N is preferably 65 at% or less, more preferably 60 at% or less, still more preferably 40 at% or less.

[0054] Also, from the same viewpoint as above, when B is contained in the conductive film 12, the content of B is preferably more than 0 at%, more preferably 5 at% or more, still more preferably 10 at% or more, and even more preferably 15 at% or more. Also, when B is contained in the conductive film 12, the content of B is preferably 65 at% or less, more preferably 50 at% or less, still more preferably 40 at% or less, particularly preferably 35 at% or less, and most preferably 30 at% or less.

[0055] The conductive film 12 preferably further contains at least one of tantalum (Ta) and chromium (Cr). Specifically, examples include a TaN film containing Ta and N, a TaB film containing Ta and B, a CrN film containing Cr and N, and a CrB film containing Cr and B. Among these, the TaN film is preferable because it has high film hardness and large film stress.

[0056] When using a TaN film as the conductive film 12, if the N content in the TaN film exceeds 0 at%, it is preferable because the hardness of the TaN film with respect to the substrate 11 is improved, more preferably 2 at% or more, further preferably 10 at% or more, and particularly preferably 15 at% or more. If the N content in the TaN film is 65 at% or less, it is preferable because the surface smoothness of the TaN film is improved and the sheet resistance value of the TaN film is reduced, more preferably 60 at% or less, further preferably 55 at% or less.

[0057] When using a TaB film as the conductive film 12, if the B content in the TaB film exceeds 0 at%, it is preferable because the film adhesion and surface smoothness are improved, more preferably 5 at% or more, further preferably 10 at% or more, particularly preferably 15 at% or more, and most preferably 20 at% or more. If the B content in the TaB film is 35 at% or less, it is preferable because the hardness is improved, more preferably 30 at% or less.

[0058] When using a CrN film as the conductive film 12, if the N content in the CrN film exceeds 0 at%, it is preferable because the hardness of the CrN film with respect to the substrate 11 is improved, more preferably 1 at% or more, further preferably 2 at% or more. If the N content in the CrN film is 65 at% or less, it is preferable because the surface smoothness of the CrN film is improved and the sheet resistance value of the CrN film is reduced, more preferably 50 at% or less, further preferably 30 at% or less, and particularly preferably 15 at% or less.

[0059] A laminated film of a TaN film and a CrN film may be used as the conductive film 12. Since the laminated film having the above configuration contains a TaN film, it has high film hardness and large film stress.

[0060] When using the laminated film with the above structure, it is preferable to use a laminated film laminated in the order of TaN film and CrN film from the substrate 11 side. When using the laminated film with the above structure, the total film thickness of the laminated film satisfies the film thickness of the conductive film 12 described above. Also, the N content in the TaN film and the N content in the CrN film satisfy the above-described ranges, respectively.

[0061] Also, an upper layer may be further provided on the conductive film 12. The upper layer is preferably a film containing chromium (Cr) and at least one element selected from the group consisting of nitrogen (N) and oxygen (O). By further providing an upper layer on the conductive film 12, improvement in mechanical properties and suppression of changes in optical properties due to the formation of a natural oxide film can be achieved.

[0062] When using a CrO film as the upper layer of the conductive film 12, it is preferable that the O content in the CrO film is 5 at% or more because the hardness of the CrO film is improved, more preferably 8 at% or more, and even more preferably 10 at% or more. When the O content in the CrO film is 30 at% or less, the surface smoothness of the CrO film is improved and the sheet resistance value of the CrO film is decreased, which is preferable, more preferably 25 at% or less, even more preferably 20 at% or less, and particularly preferably 15 at% or less.

[0063] The film thickness t' of the upper layer of the conductive film 12 is preferably 5 nm or more, more preferably 10 nm or more, even more preferably 15 nm or more, and particularly preferably 20 nm or more. The film thickness t' of the upper layer of the conductive film 12 is preferably 100 nm or less, more preferably 70 nm or less, and even more preferably 50 nm or less.

[0064] When the conductive film 12 contains Ta, among the diffraction peaks derived from the conductive film 12 observed by the out-of-plane XRD method, it is preferable that the full width at half maximum (FWHM) of the diffraction peak attributed to the bcc(110) plane of Ta is 1.5 to 4.0°. When the FWHM of the half value width is 1.5° or more, the crystallization of the conductive film is suppressed, and the smoothness of the surface of the conductive film 12 is increased. The FWHM of the half value width is more preferably 2.0° or more, and even more preferably 3.0° or more.

[0065] On the other hand, when the FWHM of the half value width is 4.0° or less, the crystallinity of the conductive film does not become too low, so the hardness of the film does not decrease. Therefore, it does not wear due to repeated use and the superposition accuracy does not decrease.

[0066] The resistivity of the conductive film 12 is 3.5 mΩ·cm or less. Generally, the fixing force of the EUV mask to the exposure apparatus improves as the resistivity of the conductive film 12 decreases. In the present embodiment, since the resistivity of the conductive film 12 is sufficiently low at 3.5 mΩ·cm or less, an excellent fixing force can be obtained when fixing the EUV mask to the exposure apparatus. The resistivity of the conductive film 12 is preferably 1.0 mΩ·cm or less, more preferably 0.320 mΩ·cm or less, even more preferably 0.300 mΩ·cm or less, and particularly preferably 0.250 mΩ·cm or less.

[0067] Also, the lower limit of the resistivity of the conductive film 12 is not particularly limited, but it is preferably 0.050 mΩ·cm or more, more preferably 0.060 mΩ·cm or more, and even more preferably 0.065 mΩ·cm or more.

[0068] The resistivity of the conductive film 12 is measured with a resistivity meter, and the detailed measurement conditions follow the measurement method of the examples in the latter stage.

[0069] In order to make the resistivity of the conductive film 12 within the above range, a method of adjusting the nitrogen or boron content contained in the conductive film can be mentioned. Even when an upper layer is further provided on the conductive film 12, when the resistivity of the conductive film is sufficiently lower than that of the upper layer, the resistivity during lamination can be regarded as the resistivity of the conductive film as it is. Examples of the combination of the conductive film and the upper layer such that the resistivity of the conductive film is sufficiently lower than that of the upper layer include, for example, a combination of a TaN film as the conductive film and a CrO film as the upper layer.

[0070] The conductive film 12 preferably has a low sheet resistance value because the chucking force by the electrostatic chuck is improved. The sheet resistance value of the conductive film 12 is preferably 250 Ω / sq or less, more preferably 200 Ω / sq or less, still more preferably 150 Ω / sq or less, even more preferably 100 Ω / sq or less, and particularly preferably 80 Ω / sq or less.

[0071] Also, the sheet resistance value of the conductive film 12 is preferably 0.1 Ω / sq or more, more preferably 0.5 Ω / sq or more, and still more preferably 1.0 Ω / sq or more.

[0072] The conductive film 12 preferably has a small surface roughness because the adhesion with the electrostatic chuck is improved. The surface roughness of the conductive film 12 is preferably 0.600 nm or less in terms of Rq (root mean square height, JIS B0601:2013), more preferably 0.400 nm or less, still more preferably 0.200 nm or less, particularly preferably 0.150 nm or less, and most preferably 0.100 nm or less. The surface roughness of the conductive film 12 is preferably 0.030 nm or more, more preferably 0.050 nm or more, and still more preferably 0.070 nm or more in terms of Rq. When the gas pressure of the gas used during film formation is 0.3 Pa or more, the surface roughness of the conductive film tends to increase.

[0073] The conductive film 12 preferably has a high surface hardness because the generation of particles due to rubbing with the electrostatic chuck is suppressed. The surface hardness of the conductive film 12 is preferably 10.0 GPa or more.

[0074] Further, the surface hardness of the conductive film 12 is preferably 16.0 GPa or less, more preferably 14.0 GPa or less, and even more preferably 12.0 GPa or less. Here, the method for measuring the surface hardness of the conductive film 12 is not particularly limited, and known methods can be used, specifically, for example, Vickers hardness test, Rockwell hardness test, Brinell hardness test, nanoindentation test, etc. Among these, the nanoindentation test is widely used when measuring the surface hardness of thin films.

[0075] In addition, if a TaN film, a CrN film, or a laminated film of a CrN film and a TaN film is used as the conductive film 12, the surface hardness of the conductive film 12 is high, and the surface hardness becomes 10.0 GPa or more.

[0076] In the EUV mask blank 10 shown in FIG. 1, film stress occurs in the reflective layer 13 and the absorption layer 14 formed on the front surface side of the substrate 11. Film stress also occurs in the conductive film 12 formed on the back surface side of the substrate 11. In the EUV mask blank, the stress generated on the front surface side of the substrate 11 and the stress generated on the back surface side of the substrate 11 cancel each other out, thereby suppressing the deformation of the substrate caused by the applied stress.

[0077] As an example of the EUV mask blank, when suppressing the deformation of the substrate in the EUV mask blank having the following configuration, the flatness of the substrate with the conductive film 12 formed on the back surface side of the substrate 11 is preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less.

[0078] (Configuration) Substrate: SiO2-TiO2-based glass substrate (outer shape: 152 mm square, thickness: 6.3 mm) Reflective layer: Si / Mo multilayer reflective film (alternately laminated 40 cycles of Si film (4.5 nm) and Mo film (2.3 nm) (total film thickness: 272 nm)) Absorption layer: TaNH film (film thickness: 60 nm)

[0079] In addition, if a TaN film, a TaB film, or a laminated film of a CrN film and a TaN film is used as the conductive film 12, the film stress of the conductive film 12 is large, and the flatness of the substrate with the conductive film becomes 500 nm or less.

[0080] When manufacturing an EUV mask from an EUV mask blank, heat treatment may be performed as a pretreatment. Due to this heat treatment, the film stress of the reflective layer 13 and the absorption layer 14 formed on the front surface side of the substrate 11 decreases due to relaxation of the film stress. In addition, the film stress of the conductive film 12 formed on the back surface side of the substrate 11 decreases due to relaxation of the film stress. When the stress decreases due to relaxation of the film stress, deformation of the substrate 11 cannot be suppressed, and there is a risk of causing misalignment in the pattern formed on the EUV mask manufactured using the EUV mask blank.

[0081] The conductive film 12 preferably has little relaxation of film stress due to heat treatment. The difference in flatness of the substrate with the conductive film measured before and after heat treatment can be used as an index of relaxation of film stress due to heat treatment. When the substrate 11 with the conductive film 12 formed on the back surface side is heat-treated at 136 °C for 20 minutes, the heat relaxation rate of the flatness (warpage) obtained by the following formula of the substrate with the conductive film measured before and after heat treatment is preferably 15% or less, more preferably 12% or less, and even more preferably 10% or less. The lower limit of the heat relaxation rate of the flatness (warpage) is not particularly limited, but is, for example, 1.0% or more. Heat relaxation rate of flatness (%) = {(Flatness of the substrate with TaN conductive film before heat treatment - Flatness of the substrate with TaN conductive film after heat treatment) / Flatness of the substrate with TaN conductive film before heat treatment} × 100

[0082] The flatness is measured using a flatness measuring instrument manufactured by Fujinon Corporation.

[0083] The conductive film 12 can be formed by a known film formation method, for example, a sputtering method such as a magnetron sputtering method or an ion beam sputtering method.

[0084] When forming a TaN film as the conductive film 12 by sputtering, for example, the sputtering method may be carried out using a Ta target in an atmosphere containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe) as an inert gas and nitrogen (N₂). When using the magnetron sputtering method, specifically, it may be carried out under the following film formation conditions.

[0085] (Film formation conditions) Target: Ta target Sputtering gas: A mixed gas of Ar and N₂ (N₂ gas concentration: preferably 2 to 50 vol%, more preferably 2 to 40 vol%, still more preferably 2 to 30 vol%. Gas pressure: preferably 1×10 -1 Pa to 3×10 -1 Pa, more preferably 1×10 -1 Pa to 2×10 -1 Pa, still more preferably 1×10 -1 Pa to 1.5×10 -1 Pa.) Input power: preferably 300 to 1500 W, more preferably 500 to 1000 W Film formation rate: preferably 0.010 to 0.200 nm / sec, more preferably 0.050 to 0.100 nm / sec

[0086] When forming a TaB film as the conductive film 12 by sputtering, for example, the sputtering method may be carried out using a Ta target and a B target, or a TaB compound target in an atmosphere containing an inert gas containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe). When using the magnetron sputtering method, specifically, it may be carried out under the following film formation conditions.

[0087] (Film formation conditions) Target: Ta target and B target, or TaB compound target Sputtering gas: Ar gas (Gas pressure: preferably 1.0×10-1 Pa to 5.0×10 -1 Pa, more preferably 1.0×10 -1 Pa to 4.0×10 -1 Pa, even more preferably 1.0×10 -1 Pa to 3.0×10 -1 Pa.) Input power: preferably 300 - 1500 W, more preferably 500 - 1000 W Film formation rate: preferably 0.010 - 0.200 nm / sec, more preferably 0.010 - 0.100 nm / sec

[0088] When forming a CrN film as the conductive film 12 by, for example, sputtering method, the sputtering method may be carried out using a Cr target in an atmosphere containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe) as an inert gas and nitrogen (N2). When using the magnetron sputtering method, specifically, it may be carried out under the following film formation conditions.

[0089] (Film formation conditions) Target: Cr target Sputtering gas: a mixed gas of Ar and N2 (N2 gas concentration: preferably 20 - 60 vol%, more preferably 30 - 60 vol%, even more preferably 40 - 60 vol%. Gas pressure: preferably 1×10 -1 Pa to 3×10 -1 Pa, more preferably 1×10 -1 Pa to 2×10 -1 Pa, even more preferably 1×10 -1 Pa to 1.5×10 -1 Pa.) Input power: preferably 300 - 2000 W, more preferably 500 - 2000 W Film formation rate: preferably 0.010 - 0.200 nm / sec, more preferably 0.050 - 0.200 nm / sec

[0090] When forming a CrO film as an upper layer on, for example, a conductive film 12 by a sputtering method, the sputtering method may be carried out using a Cr target in an atmosphere containing at least one of helium (He), argon (Ar), neon (Ne), krypton (Kr), and xenon (Xe) as an inert gas and oxygen (O₂). When using a magnetron sputtering method, specifically, it may be carried out under the following film formation conditions.

[0091] (Film formation conditions) Target: Cr target Sputtering gas: A mixed gas of Ar and O₂ (O₂ gas concentration: preferably 10 - 40 vol%, more preferably 20 - 40 vol%, still more preferably 30 - 40 vol%. Gas pressure: preferably 1×10 -1 Pa - 2.0×10 -1 Pa, more preferably 1×10 -1 Pa - 1.8×10 -1 Pa, still more preferably 1×10 -1 Pa - 1.6×10 -1 Pa.) Input power: preferably 300 - 1000 W, more preferably 500 - 1000 W Film formation rate: preferably 0.010 - 0.200 nm / sec, more preferably 0.050 - 0.200 nm / sec

[0092] The reflective layer 13 is not particularly limited as long as it has desired characteristics as the reflective layer of the EUV mask blank. Here, the characteristic particularly required for the reflective layer 13 is high EUV light reflectivity. Specifically, when irradiating the surface of the reflective layer 13 with light in the wavelength region of EUV light at an incident angle of 6 degrees, the maximum value of the light reflectivity near a wavelength of 13.5 nm is preferably 60% or more, and more preferably 65% or more.

[0093] As the reflective layer 13, since it can achieve a high EUV light reflectivity, usually a multilayer reflective film in which a plurality of high refractive index layers and low refractive index layers are alternately laminated multiple times is used. In the multilayer reflective film forming the reflective layer 13, Mo is widely used for the high refractive index layer, and Si is widely used for the low refractive index layer. That is, the Mo / Si multilayer reflective film is the most common. However, the multilayer reflective film is not limited to this, and Ru / Si multilayer reflective film, Mo / Be multilayer reflective film, Mo compound / Si compound multilayer reflective film, Si / Mo / Ru multilayer reflective film, Si / Mo / Ru / Mo multilayer reflective film, Si / Ru / Mo / Ru multilayer reflective film can also be used.

[0094] The film thickness of each layer constituting the multilayer reflective film forming the reflective layer 13 and the number of repeating units of the layer can be appropriately selected according to the film material used and the EUV light reflectivity required for the reflective layer. Taking the Mo / Si multilayer reflective film as an example, in order to make the reflective layer 13 have a maximum EUV light reflectivity of 60% or more, the multilayer reflective film may be laminated such that the Mo layer has a film thickness of 2.3 ± 0.1 nm, the Si layer has a film thickness of 4.5 ± 0.1 nm, and the number of repeating units is 30 to 60.

[0095] In addition, each layer constituting the multilayer reflective film forming the reflective layer 13 may be formed to a desired thickness using a well-known film forming method such as magnetron sputtering method or ion beam sputtering method. For example, when forming a Si / Mo multilayer reflective film using the ion beam sputtering method, a Si target is used as the target, and Ar gas (gas pressure 1.3×10 -2 ~2.7×10 -2 Pa) is used, and a Si film is formed to a thickness of 4.5 nm at an ion acceleration voltage of 300 to 1500 V and a film forming speed of 0.030 to 0.300 nm / sec. Next, a Mo target is used as the target, and Ar gas (gas pressure 1.3×10 -2 ~2.7×10 -2 Pa) is used, and it is preferable to form a Mo film to a thickness of 2.3 nm at an ion acceleration voltage of 300 V to 1500 V and a film forming speed of 0.030 to 0.300 nm / sec. Taking this as one cycle, a Si / Mo multilayer reflective film is formed by laminating the Si film and the Mo film 40 to 50 cycles.

[0096] The characteristic particularly required for the absorption layer 14 is that the EUV light reflectivity is extremely low. Specifically, when irradiating the surface of the absorption layer 14 with light in the wavelength region of EUV light, the maximum light reflectivity near a wavelength of 13.5 nm is preferably 5% or less, more preferably 3% or less, and even more preferably 1% or less.

[0097] To achieve the above characteristics, the absorption layer 14 is made of a material with a high EUV light absorption coefficient. As a material with a high EUV light absorption coefficient, it is preferable to use a material mainly composed of tantalum (Ta). In this specification, when referring to a material mainly composed of tantalum (Ta), it means a material containing 20 at% or more of Ta in the material. The absorption layer 14 preferably contains 30 at% or more of Ta, more preferably 35 at% or more, even more preferably 40 at% or more, particularly preferably 45 at% or more, and most preferably 50 at% or more.

[0098] The material mainly composed of Ta used for the absorption layer 14 contains at least one component among hafnium (Hf), silicon (Si), zirconium (Zr), germanium (Ge), boron (B), palladium (Pd), tin (Sn), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), silver (Ag), cadmium (Cd), indium (In), antimony (Sb), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), thallium (Tl), lead (Pb), bismuth (Bi), carbon (C), titanium (Ti), zirconium (Zr), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), calcium (Ca), magnesium (Mg), aluminum (Al), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), arsenic (As), selenium (Se), tellurium (Te), hydrogen (H) and nitrogen (N).

[0099] Specific examples of the material containing the above elements other than Ta include, for example, TaN, TaNH, TaHf, TaHfN, TaBSi, TaBSiN, TaB, TaBN, TaSi, TaSiN, TaGe, TaGeN, TaZr, TaZrN, TaPd, TaSn, TaPdN, TaSn, TaCr, TaMn, TaFe, TaCo, TaAg, TaCd, TaIn, TaSb, TaW, etc.

[0100] The absorption layer 14 having the above-described configuration can be formed using a film-forming method such as a sputtering method such as a magnetron sputtering method or an ion beam sputtering method.

[0101] For example, when forming a TaNH film as the absorption layer 14 using a magnetron sputtering method, a Ta target is used as the target, and as the sputtering gas, a mixed gas of Ar, N2, and H2 (H2 gas concentration: 1 to 30 vol%, N2 gas concentration: 5 to 75 vol%, Ar gas concentration: 10 to 94 vol%, gas pressure: 0.5×10 -1 ~1.0 Pa), input power 300 to 2000 W, film-forming speed 0.5 to 60 nm / min, and it is preferable to form a film so as to have a thickness of 20 to 90 nm.

[0102] The EUV mask blank 10 of the present embodiment may have a configuration other than the configuration shown in FIG. 1, that is, the substrate 11, the conductive film 12, the reflective layer 13, and the absorption layer 14.

[0103] In the EUV mask blank of this embodiment, a protective layer may be formed between the reflective layer 13 and the absorption layer 14. The protective layer is provided for the purpose of protecting the reflective layer 13 so that the reflective layer 13 is not damaged by the etching process when patterning the absorption layer 14 by an etching process, usually a dry etching process. Therefore, as the material of the protective layer, a material that is less affected by the etching process of the absorption layer 14, that is, a material whose etching rate is slower than that of the absorption layer 14 and that is less likely to be damaged by this etching process is selected. In order to satisfy the above characteristics, the protective layer is preferably made of a material containing ruthenium (Ru). Specific examples of the material containing Ru include Ru and Ru compounds (RuB, RuSi, RuNb, RuTi, RuY, RuZr, RuLa, etc.). As the material containing Ru, a material containing 40.0 at% or more of Ru in the material is preferred, more preferably 50.0 at% or more, and still more preferably 55.0 at% or more.

[0104] When forming the protective layer, its thickness is preferably 1 to 20 nm, more preferably 1 to 5 nm.

[0105] When forming the protective layer, a well-known film-forming method such as magnetron sputtering method or ion beam sputtering method is used for film formation. When forming a Ru film by the magnetron sputtering method, a Ru target is used as the target, and Ar gas (gas pressure: 1.0×10 -2 ~10×10 -1 Pa) is used, and it is preferable to form a film with a thickness of 2 to 5 nm at an input voltage of 30 to 1500 V and a film formation rate of 0.020 to 1.000 nm / sec.

[0106] Note that even when a protective layer is provided on the reflective layer 13, the maximum value of the light reflectance near a wavelength of 13.5 nm is preferably 60% or more, more preferably 63% or more, and still more preferably 65% or more.

[0107] Furthermore, in the EUV mask blank of the present embodiment, a low-reflection layer in inspection light used for inspecting the mask pattern may be formed on the absorption layer 14.

[0108] The low-reflection layer is composed of a film that provides low reflection in the inspection light used for inspecting the mask pattern. When manufacturing an EUV mask, after forming a pattern on the absorption layer, it is inspected whether the pattern is formed as designed. In this inspection of the mask pattern, an inspection apparatus that uses light of about 257 nm is usually used as the inspection light. That is, it is inspected based on the difference in reflectance of this light of about 257 nm, specifically, the difference in reflectance between the surface where the absorption layer is removed by pattern formation and exposed, and the surface of the absorption layer that remains without being removed by pattern formation.

[0109] Here, the former is the surface of the reflective layer or the protective layer, and usually the surface of the protective layer. Therefore, if the difference in reflectance between the surface of the reflective layer or the protective layer and the surface of the absorption layer with respect to the wavelength of the inspection light is small, the contrast during inspection deteriorates and accurate inspection cannot be performed. When the difference in reflectance between the surface of the reflective layer or the protective layer and the surface of the absorption layer with respect to the wavelength of the inspection light is small, the formation of a low-reflection layer results in good contrast during inspection. When forming a low-reflection layer on the absorption layer, when the light in the wavelength region of the inspection light is irradiated on the surface of the low-reflection layer, the maximum light reflectance of the wavelength of the inspection light is preferably 15% or less, more preferably 10% or less, and even more preferably 5% or less.

[0110] The low-reflection layer is preferably composed of a material having a refractive index lower than that of the absorption layer in order to achieve the above characteristics.

[0111] Examples of the low-reflection layer that satisfies this property include those containing at least one selected from the group consisting of tantalum (Ta), palladium (Pd), chromium (Cr), silicon (Si), and hafnium (Hf), and at least one selected from the group consisting of oxygen (O) and nitrogen (N). Preferred examples of such low-reflection layers include TaPdO layer, TaPdON layer, TaON layer, CrO layer, CrON layer, SiON layer, SiN layer, HfO layer, and HfON layer.

[0112] The total content ratio of Ta, Pd, Cr, Si, and Hf in the low-reflection layer is preferably 10 to 55 at%, particularly 10 to 50 at%, because the optical properties with respect to the wavelength region of the pattern inspection light can be controlled.

[0113] Also, the total content ratio of O and N in the low-reflection layer is preferably 45 to 90 at%, particularly 50 to 90 at%, because the optical properties with respect to the wavelength region of the pattern inspection light can be controlled. The total content ratio of Ta, Pd, Cr, Si, Hf, O, and N in the low-reflection layer is preferably 95 to 100 at%, more preferably 97 to 100 at%, and even more preferably 99 to 100 at%.

[0114] The low-reflection layer having the above-described configuration can be formed by performing a sputtering method using a target containing at least one of Ta, Pd, Cr, Si, and Hf. Here, as the target, any of the above-described two or more types of metal targets and compound targets can be used.

[0115] The use of two or more types of metal targets is convenient for adjusting the constituent components of the low-reflection layer. When using two or more types of metal targets, the constituent components of the absorption layer can be adjusted by adjusting the input power to the targets. On the other hand, when using a compound target, it is preferable to adjust the target composition in advance so that the formed low-reflection layer has a desired composition.

[0116] The sputtering method using the above target can be carried out in an inert gas atmosphere, similar to the sputtering method for forming an absorption layer.

[0117] However, when the low-reflection layer contains oxygen (O), the sputtering method is carried out in an inert gas atmosphere containing at least one of He, Ar, Ne, Kr, and Xe and O2. When the low-reflection layer contains N, the sputtering method is carried out in an inert gas atmosphere containing at least one of He, Ar, Ne, Kr, and Xe and N2. When the low-reflection layer contains O and N, the sputtering method is carried out in an inert gas atmosphere containing at least one of He, Ar, Ne, Kr, and Xe and O2 and N2.

[0118] The specific implementation conditions of the sputtering method vary depending on the target used and the composition of the inert gas atmosphere in which the sputtering method is carried out, but in any case, the sputtering method may be carried out under the following conditions. Taking the case where the inert gas atmosphere is a mixed gas atmosphere of Ar and O2 as an example, the formation conditions of the low-reflection layer are shown below.

[0119] (Formation conditions of the low-reflection layer) Gas pressure: 1.0×10 -1 ~50×10 -1 Pa, preferably 1.0×10 -1 ~40×10 -1 Pa, more preferably 1.0×10 -1 ~30×10 -1 Pa. Sputtering gas: A mixed gas of Ar and O2 (O2 gas concentration: 3 to 80 vol%, preferably 5 to 60 vol%, more preferably 10 to 40 vol%) Input power: 30 to 1000 W, preferably 50 to 750 W, more preferably 80 to 500 W Film formation rate: 0.01 to 60 nm / min, preferably 0.05 to 45 nm / min, more preferably 0.1 to 30 nm / min

[0120] When using an inert gas other than Ar or a plurality of inert gases, the total concentration of the inert gases is set to the same concentration range as the above-mentioned Ar gas concentration. Further, when the inert gas atmosphere contains N2, the N2 concentration is set to the same concentration range as the above-mentioned oxygen concentration, and when the inert gas atmosphere contains N2 and O2, the total concentration is set to the same concentration range as the above-mentioned oxygen concentration.

[0121] In the EUV mask blank of this embodiment, it is preferable to form a low reflection layer on the absorption layer because the wavelength of the inspection light for the pattern is different from the wavelength of the EUV light. Therefore, when using EUV light (around 13.5 nm) as the inspection light for the pattern, it is considered that there is no need to form a low reflection layer on the absorption layer. The wavelength of the inspection light tends to shift to the short wavelength side as the pattern size becomes smaller, and it is also considered that it will shift to 193 nm and further to 13.5 nm in the future. When the wavelength of the inspection light is 13.5 nm, it is considered that there is no need to form a low reflection layer on the absorption layer.

[0122] In the EUV mask blank of this embodiment, on the absorption layer 14 (when a low reflection layer is formed on the absorption layer, it is on the absorption layer), a hard mask layer described in Japanese Patent Application Laid-Open No. 2009-54899 or Japanese Patent Application Laid-Open No. 2009-21582, that is, a layer of a material having resistance to the etching conditions of the absorption layer (when a low reflection layer is formed on the absorption layer, it is the absorption layer and the low reflection layer), may be formed. By forming such a hard mask layer and increasing the etching selectivity ratio between the absorption layer (when a low reflection layer is formed on the absorption layer, it is the absorption layer and the low reflection layer) and the hard mask layer under the etching conditions of the absorption layer (when a low reflection layer is formed on the absorption layer, it is the absorption layer and the low reflection layer), specifically, the etching rate of the absorption layer (when a low reflection layer is formed on the absorption layer, it is the etching rate of the absorption layer and the low reflection layer) under the etching conditions of the absorption layer (when a low reflection layer is formed on the absorption layer, it is the absorption layer and the low reflection layer) and the etching rate of the hard mask layer, the resist can be thinned.

[0123] Next, the substrate with a conductive film according to this embodiment will be described. The substrate with a conductive film according to this embodiment has a conductive film on the substrate. Here, the substrate and the conductive film are the same as the substrate and the conductive film in the EUV mask blank of this embodiment. That is, the EUV mask blank of this embodiment is formed by forming a reflective layer and an absorption layer on the surface opposite to the surface of the substrate with the conductive film of this embodiment where the conductive film is provided.

[0124] As described above, the following configurations are disclosed in this specification. (1) A substrate, A conductive film disposed on the back side of the substrate, A reflective layer disposed on the front side of the substrate that reflects EUV light, And an absorption layer disposed on the reflective layer that absorbs EUV light, a reflective mask blank for EUV lithography, The conductive film contains at least one of nitrogen (N) and boron (B), The total content of N and B contained in the conductive film is more than 0 at% and 65 at% or less, The refractive index n of the conductive film at a wavelength of 1000 to 1100 nm λ1000-1100nm Is 5.300 or less, and the extinction coefficient k λ1000-1100nm Is 5.200 or less, The refractive index n of the conductive film at a wavelength of 600 to 700 nm λ600-700nm Is 4.300 or less, and the extinction coefficient k λ600-700nm Is 4.500 or less, The refractive index n of the conductive film at a wavelength of 400 to 500 nm λ400-500nm Is 2.500 or more, and the extinction coefficient k λ400-500nm Is 0.440 or more, The film thickness t of the conductive film is 20 to 350 nm, The resistivity of the conductive film is 3.5 mΩ·cm or less, a reflective mask blank for EUV lithography. (2) A substrate, A conductive film disposed on the back side of the substrate, A reflective layer disposed on the front side of the substrate that reflects EUV light, An EUV lithography reflective mask blank having an absorption layer disposed on a reflective layer and absorbing EUV light, The conductive film contains at least one of nitrogen (N) and boron (B), The total content of N and B contained in the conductive film is more than 0 at% and 65 at% or less, The refractive index n of the conductive film at a wavelength of 1000 to 1100 nm λ1000-1100nm is 5.300 or less, and the extinction coefficient k λ1000-1100nm is 5.200 or less, The refractive index n of the conductive film at a wavelength of 600 to 700 nm λ600-700nm is 4.300 or less, and the extinction coefficient k λ600-700nm is 4.500 or less, The refractive index n of the conductive film at a wavelength of 480 to 500 nm λ480-500nm is 2.500 or more, and the extinction coefficient k λ480-500nm is 0.440 or more, The film thickness t of the conductive film is 20 to 350 nm, The resistivity of the conductive film is 3.5 mΩ·cm or less. An EUV lithography reflective mask blank. (3) The EUV lithography reflective mask blank according to (1) or (2), wherein the conductive film contains at least one of tantalum (Ta) and chromium (Cr). (4) The EUV lithography reflective mask blank according to (1) or (2), wherein the conductive film contains Ta and N. (5) The EUV lithography reflective mask blank according to (4), wherein the conductive film contains N in an amount of more than 0 at% and 65 at% or less. (6) The EUV lithography reflective mask blank according to (1) or (2), wherein the conductive film contains Ta and B. (7) The EUV lithography reflective mask blank according to (6), wherein the conductive film contains B in an amount of more than 0 at% and 35 at% or less. (8) The EUV lithography reflective mask blank according to (1) or (2), wherein the resistivity of the conductive film is 0.050 mΩ·cm or more and 3.5 mΩ·cm or less. (9) The conductive film contains Ta, and in the diffraction peaks derived from the conductive film observed by the out-of-plane XRD method, the full width at half maximum FWHM of the diffraction peak attributed to the bcc(110) plane of Ta is 1.5 to 4.0°, the reflective mask blank for EUV lithography according to (3) or (4). (10) The conductive film has a light transmittance of 1.0% or more at a wavelength of 1000 to 1100 nm, a light transmittance of 1.0% or more at a wavelength of 600 to 700 nm, and a light transmittance of 1.0% or less at a wavelength of 400 to 500 nm, the reflective mask blank for EUV lithography according to any one of (1) to (4). (11) The sheet resistance value of the conductive film is 250 Ω / square or less, the reflective mask blank for EUV lithography according to any one of (1) to (4). (12) The surface hardness of the conductive film is 10.0 GPa or more, the reflective mask blank for EUV lithography according to any one of (1) to (4). (13) An upper layer is further provided on the conductive film, The upper layer contains chromium (Cr) and at least one element selected from the group consisting of nitrogen (N) and oxygen (O), the reflective mask blank for EUV lithography according to any one of (1) to (4). (14) The surface roughness (Rq) of the conductive film is 0.600 nm or less, the reflective mask blank for EUV lithography according to any one of (1) to (4). (15) A substrate with a conductive film, having a conductive film on the substrate, The conductive film contains at least one of nitrogen (N) and boron (B), The total content of N and B contained in the conductive film is more than 0 at%, 65 at% or less, The refractive index n of the conductive film at a wavelength of 1000 to 1100 nm λ1000-1100nm is 5.300 or less, and the extinction coefficient k λ1000-1100nm is 5.200 or less, The refractive index n of the conductive film at a wavelength of 600 to 700 nm λ600-700nm is 4.300 or less, and the extinction coefficient k λ600-700nm is 4.500 or less, The refractive index n of the conductive film at a wavelength of 400 to 500 nm λ400-500nm is 2.500 or more, and the attenuation coefficient k λ400-500nm is 0.440 or more, the film thickness t of the conductive film is 20 to 350 nm, A substrate with a conductive film, wherein the resistivity of the conductive film is 3.5 mΩ·cm or less. (16) A substrate with a conductive film having a conductive film on the substrate, wherein the conductive film contains at least one of nitrogen (N) and boron (B), the total content of N and B contained in the conductive film is more than 0 at% and 65 at% or less, the refractive index n of the conductive film at a wavelength of 1000 to 1100 nm λ1000-1100nm is 5.300 or less, and the attenuation coefficient k λ1000-1100nm is 5.200 or less, the refractive index n of the conductive film at a wavelength of 600 to 700 nm λ600-700nm is 4.300 or less, and the attenuation coefficient k λ600-700nm is 4.500 or less, the refractive index n of the conductive film at a wavelength of 480 to 500 nm λ480-500nm is 2.500 or more, and the attenuation coefficient k λ480-500nm is 0.440 or more, the film thickness t of the conductive film is 20 to 350 nm, A substrate with a conductive film, wherein the resistivity of the conductive film is 3.5 mΩ·cm or less. (17) The substrate with a conductive film according to (15) or (16), wherein the conductive film contains at least one of tantalum (Ta) and chromium (Cr). (18) The substrate with a conductive film according to (15) or (16), wherein the conductive film contains Ta and N. (19) The substrate with a conductive film according to (18), wherein the conductive film contains N in an amount of more than 0 at% and 65 at% or less. (20) The substrate with a conductive film according to (15) or (16), wherein the conductive film contains Ta and B. (21) The substrate with a conductive film according to (20), wherein the conductive film contains B in an amount of more than 0 at% and 35 at% or less. (22) The resistivity of the conductive film is 0.050 mΩ·cm or more and 3.5 mΩ·cm or less, and the substrate with the conductive film according to (15) or (16). (23) The conductive film contains Ta, and among the diffraction peaks derived from the conductive film observed by the out-of-plane XRD method, the full width at half maximum FWHM of the diffraction peak attributed to the bcc (110) plane of Ta is 1.5 to 4.0°, and the substrate with the conductive film according to (17) or (18). (24) The conductive film has a light transmittance of 1.0% or more at a wavelength of 1000 to 1100 nm, a light transmittance of 1.0% or more at a wavelength of 600 to 700 nm, and a light transmittance of 1.0% or less at a wavelength of 400 to 500 nm, and the substrate with the conductive film according to any one of (15) to (18). (25) The sheet resistance value of the conductive film is 250 Ω / square or less, and the substrate with the conductive film according to any one of (15) to (18). (26) The surface hardness of the conductive film is 10.0 GPa or more, and the substrate with the conductive film according to any one of (15) to (18). (27) An upper layer is further provided on the conductive film, The upper layer contains chromium (Cr) and at least one element selected from the group consisting of nitrogen (N) and oxygen (O), and the substrate with the conductive film according to any one of (15) to (18). (28) The surface roughness (Rq) of the conductive film is 0.600 nm or less, and the substrate with the conductive film according to any one of (15) to (18).

Example

[0125] The present invention will be described in more detail below using Examples 1 to 10, but the present invention is not limited to these examples. Examples 1 to 3, 5, and 10 are examples, and Examples 4, 6 to 9 are comparative examples.

[0126] <Example 1> In this example, a TaN film was formed as a conductive film on one surface of the substrate. As a substrate for film formation, a SiO2-TiO2-based glass substrate (outer shape: 6 inches (152 mm) square, thickness: 6.3 mm) was used. The thermal expansion coefficient of this glass substrate at 20 °C is 0.02×10 -7 / °C, the Young's modulus is 67 GPa, the Poisson's ratio is 0.17, and the specific stiffness is 3.07×10 7 m 2 / s 2 . This glass substrate was polished to form a smooth surface with a surface roughness (Rq) of 0.15 nm or less and flatness of 100 nm or less.

[0127] On one side of the substrate, a TaN film was formed as a conductive film using the magnetron sputtering method. The film formation conditions for the TaN film are as follows. (Film formation conditions) Target: Ta target Sputtering gas: Mixed gas of Ar and N2 (Ar: 90 vol%, N2: 10 vol%, gas pressure: 0.12 Pa) Input power: 1000 W Film formation rate: 6 nm / min Film thickness: 56 nm

[0128] (Composition analysis of TaN film) The composition of the TaN film was measured using a Rutherford Backscattering Spectrometry (RBS) and X-ray Photoelectron Spectrometer. The N content of the TaN film was 21.0 at%.

[0129] (Refractive index n and extinction coefficient k) For the formed TaN film, the refractive index n λ1000-1100nm , and the extinction coefficient k λ1000-1100nm were determined using a spectroscopic ellipsometer (manufacturer: J.A. Woollam, model: M2000-DI). Light was incident from the side where the TaN film was formed, and the polarization state was measured and analyzed at room temperature to obtain the refractive index n λ1000-1100nm , and the extinction coefficient k λ1000-1100nmwas calculated. Also, in the same procedure, the refractive index n λ600-700nm and the extinction coefficient k λ600-700nm at wavelengths of 600 to 700 nm, the refractive index n λ400-500nm and the extinction coefficient k λ400-500nm at wavelengths of 400 to 500 nm, and the refractive index n λ480-500nm and the extinction coefficient k λ480-500nm at wavelengths of 480 to 500 nm were calculated. The results are shown in Table 2.

[0130] (Light transmittance) For the substrate after TaN film formation, light was perpendicularly incident from the surface on which the TaN film was formed, and the light transmittance in the wavelength range of 175 to 2000 nm was measured using a spectrophotometer (manufacturer: Hitachi High-Technologies Corporation, model: U-4100). The light transmittance at wavelengths of 1000 to 1100 nm, the light transmittance at wavelengths of 600 to 700 nm, and the light transmittance at wavelengths of 400 to 500 nm were determined. When the light transmittance at wavelengths of 1000 to 1100 nm was 1.0% or more, the light transmittance at wavelengths of 600 to 700 nm was 1.0% or more, and the light transmittance at wavelengths of 400 to 500 nm was 1.0% or less, it was marked as 〇; if any one of these conditions was not met, it was marked as ×. The results are shown in Table 1.

[0131] (XRD full width at half maximum FWHM) For the TaN film, measurement was carried out by the out-of-plane XRD method. Among the diffraction peaks derived from the TaN film, the full width at half maximum FWHM of the main peak of the diffraction peak attributed to the bcc(110) plane of Ta was measured in the range of diffraction angles of 30 to 40°. The results are shown in Table 1.

[0132] (Surface hardness) The surface hardness of the TaN film was measured by a nanoindentation test. When the surface hardness was 10.0 GPa or more, it was marked as 〇; when the surface hardness was less than 10.0 GPa, it was marked as ×. The results are shown in Table 1.

[0133] (Resistivity) The resistivity of the TaN film was calculated under the following conditions. When the resistivity was 3.5 mΩ·cm or less, it was marked as ○, and when it exceeded 3.5 mΩ·cm, it was marked as ×. If the resistivity was sufficiently low at 3.5 mΩ·cm or less, it could be considered that sufficient fixing force was obtained when fixing the EUV mask fabricated from the EUV mask blank to the exposure apparatus. The resistivity was evaluated from the surface of the conductive film of the sample. · Evaluation apparatus: Loresta-GX, manufactured by Nitto Seiko Analytic Co., Ltd. · Number of measurement points: 9 points · Measurement range: 149 mm × 149 mm

[0134] (Surface roughness) The surface roughness (root mean square surface roughness RQ) was measured in a range of 2 μm × 2 μm using an atomic force microscope (AFM) manufactured by SII.

[0135] (Thermal relaxation rate of flatness) The flatness of the substrate with the TaN film after TaN film formation was measured using a flatness measuring machine manufactured by Fujinon. Next, the flatness of the substrate with the TaN film after heat-treating the substrate with the TaN film at 136°C for 20 minutes was measured using a flatness measuring machine manufactured by Fujinon. Next, the thermal relaxation rate of flatness was calculated by the following formula. When the thermal relaxation rate of flatness was 15% or less, it was marked as ○, and when it exceeded 15%, it was marked as ×. Thermal relaxation rate of flatness (%) = {(Flatness of the substrate with the TaN film before heat treatment - Flatness of the substrate with the TaN film after heat treatment) / Flatness of the substrate with the TaN film before heat treatment} × 100

[0136] <Example 2> In this example, a laminated film of a TaN film and a CrN film was formed as a conductive film on one surface of the substrate using the magnetron sputtering method. The film formation conditions of the TaN film and the CrN film are as follows, respectively. (TaN film) Target: Ta target Sputtering gas: Mixed gas of Ar and N2 (Ar: 60 vol%, N2: 40 vol%, gas pressure: 0.11 Pa) Input power: 1000 W Film formation rate: 3.9 nm / min Film thickness: 23 nm (CrN film) Target: Cr target Sputtering gas: Mixed gas of Ar and N2 (Ar: 53 vol%, N2: 47 vol%, gas pressure: 0.10 Pa) Input power: 1700 W Film deposition rate: 11.4 nm / min Film thickness: 26 nm

[0137] (Composition analysis of TaN film and CrN film) The compositions of the TaN film and the CrN film were measured using RBS. The N content rate of the TaN film was 59.0 at%, and the N content rate of the CrN film was 4.2 at%.

[0138] (Refractive index n, extinction coefficient k) The refractive index n and extinction coefficient k of the multilayer film were measured in the same procedure as in Example 1. The results are shown in Table 2. Note that the refractive index n and extinction coefficient k described in Table 2 show the values of the TaN film, and the refractive index n and extinction coefficient k of the CrN film were the same as the values in Examples 3, 4, and 9.

[0139] (Light transmittance) The light transmittance of the multilayer film was measured in the same procedure as in Example 1. The results are shown in Table 1. (XRD full width at half maximum FWHM) For the TaN film, measurement was carried out by the out-of-plane XRD method, and the full width at half maximum FWHM of the diffraction peak attributed to the bcc (110) plane of Ta in the diffraction peaks derived from the TaN film was measured in the range of diffraction angle 30 to 40°. The results are shown in Table 1.

[0140] (Surface hardness) The surface hardness of the multilayer film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0141] (Resistivity) The resistivity of the multilayer film was measured by the same measurement method as in the case of Example 1. At this time, the resistivities of the TaN film and the CrN film were measured. The results are shown in Table 1.

[0142] (Surface roughness) The surface roughness of the laminated film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0143] (Thermal relaxation rate of flatness) The thermal relaxation rate of the flatness of the substrate with the laminated film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0144] <Example 3> In this example, a CrN film was formed as a conductive film on one surface of the substrate using the magnetron sputtering method. The film formation conditions of the CrN film are as follows. (Film formation conditions) Target: Cr target Sputtering gas: Mixed gas of Ar and N2 (Ar: 53 vol%, N2: 47 vol%, gas pressure: 0.10 Pa) Input power: 1700 W Film formation rate: 11.4 nm / min Film thickness: 40 nm

[0145] (Composition analysis of CrN film) The composition of the CrN film was measured using RBS. The N content rate of the CrN film was 4.2 at%.

[0146] (Refractive index n, extinction coefficient k) The refractive index n and extinction coefficient k of the CrN film were measured in the same procedure as in Example 1. The results are shown in Table 2.

[0147] (Light transmittance) The light transmittance of the CrN film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0148] (Surface hardness) The surface hardness of the CrN film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0149] (Resistivity) The resistivity of the CrN film was measured using the same measurement method as in Example 1. The results are shown in Table 1.

[0150] (Thermal relaxation rate of flatness) The thermal relaxation rate of the flatness of the substrate with the CrN film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0151] <Example 4> In this example, the same procedure as in Example 3 was carried out except that the film thickness of the CrN film was 360 nm.

[0152] (Composition analysis of CrN film) The composition of the CrN film was measured using RBS. The N content rate of the CrN film was 4.2 at%.

[0153] (Refractive index n, extinction coefficient k) The refractive index n and extinction coefficient k of the CrN film were measured in the same procedure as in Example 1. The results are shown in Table 2.

[0154] (Light transmittance) The light transmittance of the CrN film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0155] (Surface hardness) The surface hardness of the CrN film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0156] (Resistivity) The resistivity of the CrN film was measured using the same measurement method as in Example 1. The results are shown in Table 1.

[0157] (Thermal relaxation rate of flatness) The thermal relaxation rate of the flatness of the substrate with the CrN film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0158] <Example 5> In this example, a TaB film was formed as a conductive film on one surface of the substrate using the magnetron sputtering method. The film formation conditions of the TaB film are as follows. (Film formation conditions) Target: TaB compound target Sputtering gas: Ar gas (gas pressure: 0.205 Pa) Input power: 1000 W Film formation rate: 1.67 nm / min Film thickness: 56 nm

[0159] (Composition analysis of TaB film) The composition of the TaB film was measured using Rutherford backscattering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS). The N content of the TaB film was 0.0 at%, and the B content was 28.0 at%.

[0160] (Refractive index n, extinction coefficient k) The refractive index n and extinction coefficient k of the TaB film were measured in the same procedure as in Example 1. The results are shown in Table 2.

[0161] (Light transmittance) The light transmittance of the multilayer film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0162] (XRD full width at half maximum FWHM) For the TaB film, out-of-plane XRD measurement was performed. Among the diffraction peaks derived from the TaB film, the main peak of the diffraction peak attributed to the bcc (110) plane of Ta was measured for the full width at half maximum FWHM in the range of diffraction angles from 30° to 40°. The results are shown in Table 1.

[0163] (Surface hardness) The surface hardness of the TaB film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0164] (Resistivity) The resistivity of the TaB film was measured using the same measurement method as in Example 1. The results are shown in Table 1.

[0165] (Surface roughness) The surface roughness of the TaB film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0166] (Thermal relaxation rate of flatness) The thermal relaxation rate of the flatness of the substrate with the TaB film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0167] <Example 6> In this example, a TaON film was formed as a conductive film on one surface of the substrate using the magnetron sputtering method. The film formation conditions of the TaON film are as follows. (Film formation conditions) Target: Ta target Sputtering gas: Mixed gas of N2 and O2 (N2: 88 vol%, O2: 12 vol%, gas pressure: 0.18 Pa) Input power: 1000 W Film formation rate: 0.9 nm / min Film thickness: 60 nm

[0168] (Composition analysis of TaON film) The composition of the TaON film was measured using RBS. The N content rate of the TaON film was 6.0 at%, and the O content was 68.0 at%.

[0169] (Refractive index n, extinction coefficient k) The refractive index n and extinction coefficient k of the TaON film were measured in the same procedure as in Example 1. The results are shown in Table 2.

[0170] (Light transmittance) The light transmittance of the TaON film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0171] (Resistance value) The resistivity of the TaON film was measured using the same measurement method as in Example 1. The results are shown in Table 1.

[0172] <Example 7> In this example, a CrON film was formed as a conductive film on one surface of the substrate using the magnetron sputtering method. The film formation conditions of the CrON film are as follows. (Film formation conditions) Target: Cr target Sputtering gas: Mixed gas of Ar, N2 and O2 (Ar: 33 vol%, N2: 22 vol%, O2: 45 vol%, gas pressure: 0.09 Pa) Input power: 750 W Film formation rate: 1.86 nm / min Film thickness: 60 nm

[0173] (Refractive index n, extinction coefficient k) The refractive index n and extinction coefficient k of the CrON film were measured in the same procedure as in Example 1. The results are shown in Table 2.

[0174] (Light transmittance) The light transmittance of the CrON film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0175] <Example 8> In this example, the same procedure as in Example 1 was carried out except that the film thickness of the TaN film was set to 17 nm.

[0176] (Composition analysis of TaN film) The composition of the TaN film was measured using RBS. The N content rate of the TaN film was 21.0 at%.

[0177] (Refractive index n, extinction coefficient k) The refractive index n and extinction coefficient k of the TaN film were measured in the same procedure as in Example 1. The results are shown in Table 2.

[0178] (Light transmittance) The light transmittance of the TaN film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0179] (Thermal relaxation rate of flatness) The thermal relaxation rate of the flatness of the substrate with the TaN film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0180] <Example 9> In this example, the same procedure as in Example 3 was carried out except that the film thickness of the CrN film was set to 12 nm.

[0181] (Composition analysis of CrN film) The composition of the CrN film was measured using RBS. The N content rate of the CrN film was 4.2 at%.

[0182] (Refractive index n, extinction coefficient k) The refractive index n and extinction coefficient k of the CrN film were measured in the same procedure as in Example 1. The results are shown in Table 2.

[0183] (Light transmittance) The light transmittance of the CrN film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0184] (Thermal relaxation rate of flatness) The thermal relaxation rate of the flatness of the substrate with the CrN film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0185] <Example 10> In this example, a TaN film was formed as a conductive film on one surface of the substrate, and a CrO film was further formed as an upper layer using the magnetron sputtering method. For the TaN film, it was formed under the same film formation conditions as the TaN film in Example 2 except that the film thickness was changed. The film formation conditions of the TaN film and the CrO film are as follows, respectively.

[0186] (TaN film) Target: Ta target Sputtering gas: Mixed gas of Ar and N2 (Ar: 60 vol%, N2: 40 vol%, gas pressure: 0.11 Pa) Input power: 1000 W Film formation rate: 3.9 nm / min Film thickness: 30 nm

[0187] (CrO film) Target: Cr target Sputtering gas: Mixed gas of Ar and O2 (Ar: 66 vol%, O2: 34 vol%, gas pressure: 0.16 Pa) Input power: 750 W Film formation rate: 9.0 nm / min Film thickness: 27 nm

[0188] (Composition analysis of TaN film and CrO film) The compositions of the TaN film and the CrO film were measured using RBS. The N content rate of the TaN film was 59.0 at%, and the O content rate of the CrO film was 15.0 at%.

[0189] (Refractive index n, extinction coefficient k) The refractive index n and extinction coefficient k of the laminated film were measured in the same procedure as in Example 1. The results are shown in Table 2. Note that the refractive index n and extinction coefficient k described in Table 2 indicate the values of the CrO film, and the refractive index n and extinction coefficient k of the TaN film were the same as those of the TaN film in Example 2.

[0190] (Light transmittance) The light transmittance of the laminated film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0191] (Surface hardness) The surface hardness of the laminated film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0192] (Resistivity) The resistivity of the TaN film was measured using the same measurement method as in Example 1. The results are shown in Table 1.

[0193] (Surface roughness) The surface roughness of the laminate was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0194] (Thermal relaxation rate of flatness) The thermal relaxation rate of the flatness of the substrate with the laminated film was measured in the same procedure as in Example 1. The results are shown in Table 1.

[0195]

Table 1

[0196]

Table 2

[0197] Refractive index n λ1000-1100nm is 5.300 or less, extinction coefficient k λ1000-1100nm is 5.200 or less, refractive index n λ600-700nm is 4.300 or less, extinction coefficient k λ600-700nm is 4.500 or less, refractive index n λ400-500nmis 2.600 or more, attenuation coefficient k λ400-500nm is 0.440 or more, refractive index n λ480-500nm is 2.500 or more, attenuation coefficient k λ480-500nm is 0.440 or more, and for Examples 1, 2, 3, 5, and 10 where the film thickness t of the conductive film is 20 to 350 nm, the evaluation of the light transmittance was ○, and furthermore, the evaluation of the resistivity of the conductive film was ○.

[0198] For Example 1 where the conductive film 12 is a TaN film, Example 2 which is a laminated film of a CrN film and a TaN film, Example 5 which is a TaB film, and Example 10 where a CrO film is provided as an upper layer on the TaN film, the evaluation of the thermal relaxation rate of the flatness of the substrate with the conductive film was ○.

[0199] For Example 1 where the conductive film 12 is a TaN film, Example 2 which is a laminated film of a CrN film and a TaN film, and Example 3 which is a CrN film, the surface hardness of the conductive film 12 was 10.0 GPa or more, and the surface hardness was ○.

[0200] Refractive index n λ400-500nm is less than 2.500, attenuation coefficient k λ400-500nm is less than 0.440, refractive index n λ480-500nm is less than 2.500, attenuation coefficient k λ480-500nm For Examples 6 and 7 where it is less than 0.440, the light transmittance at wavelengths of 400 to 500 nm was higher than 1.0%, and the evaluation of the light transmittance was ×. Also, for Comparative Example 6, the evaluation of the resistivity of the conductive film was ×.

[0201] For Example 4 where the film thickness t of the conductive film exceeds 350 nm, both the light transmittance at wavelengths of 1000 to 1100 nm and the light transmittance at wavelengths of 600 to 700 nm were 0.0%, and the evaluation of the light transmittance was ×.

[0202] For Examples 8 and 9 where the film thickness t of the conductive film is less than 20 nm, the light transmittance at wavelengths of 400 to 500 nm was higher than 1.0%, and the evaluation of the light transmittance was ×.

[0203] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to such examples. It is obvious that those skilled in the art can conceive of various modifications or corrections within the scope described in the claims, and it is naturally understood that they also belong to the technical scope of the present invention. Further, within the scope not departing from the gist of the invention, the components in the above embodiments may be arbitrarily combined.

[0204] This application is based on a Japanese patent application (Japanese Patent Application No. 2023-043149) filed on March 17, 2023, the content of which is incorporated herein by reference.

Explanation of Reference Numerals

[0205] 10: EUV mask blank 11: Substrate 12: Conductive film 13: Reflective layer (multi-layer reflective film) 14: Absorbing layer

Claims

1. A substrate, A conductive film disposed on the back side of the substrate, A reflective layer disposed on the front side of the substrate that reflects EUV light, An EUV lithography reflective mask blank having an absorption layer disposed on the reflective layer that absorbs EUV light, wherein The conductive film contains at least one of nitrogen (N) and boron (B), The total content of N and B contained in the conductive film is more than 0 at% and 65 at% or less, The refractive index n of the conductive film at a wavelength of 1000 to 1100 nm λ１０００－１１００ｎｍ is 5.300 or less, and the attenuation coefficient k λ１０００－１１００ｎｍ is 5.200 or less, and The refractive index n of the conductive film at a wavelength of 600 to 700 nm λ６００－７００ｎｍ is 4.300 or less, and the attenuation coefficient k λ６００－７００ｎｍ is 4.500 or less, The refractive index n of the conductive film at a wavelength of 480 to 500 nm λ４８０－５００ｎｍ is 2.500 or more, and the attenuation coefficient k λ４８０－５００ｎｍ is 0.440 or more, The film thickness t of the conductive film is 20 to 350 nm, The resistivity of the conductive film is 3.5 mΩ·cm or less, The sheet resistance value of the conductive film is 0.1 Ω / □ or more and 250 Ω / □ or less, An EUV lithography reflective mask blank.

2. The EUV lithography reflective mask blank according to claim 1, wherein the conductive film contains at least one of tantalum (Ta) and chromium (Cr).

3. The EUV lithography reflective mask blank according to claim 1 or 2, wherein the conductive film contains Ta and N.

4. The EUV lithography reflective mask blank according to claim 3, wherein the conductive film contains N in an amount of more than 0 at% and 65 at% or less.

5. The EUV lithography reflective mask blank according to claim 1 or 2, wherein the conductive film contains Ta and B.

6. The EUV lithography reflective mask blank according to claim 5, wherein the conductive film contains B in an amount of more than 0 at% and 35 at% or less.

7. The EUV lithography reflective mask blank according to claim 1 or 2, wherein the resistivity of the conductive film is 0.050 mΩ·cm or more and 3.5 mΩ·cm or less.

8. The EUV lithography reflective mask blank according to claim 1 or 2, wherein the conductive film contains Ta, and in the diffraction peaks derived from the conductive film observed by the out of plane XRD method, the full width at half maximum (FWHM) of the diffraction peak attributed to the bcc (110) plane of Ta is 1.5 to 4.0°.

9. The EUV lithography reflective mask blank according to claim 1 or 2, wherein the light transmittance of the conductive film at a wavelength of 1000 to 1100 nm is 1.0% or more, the light transmittance at a wavelength of 600 to 700 nm is 1.0% or more, and the light transmittance at a wavelength of 400 to 500 nm is 1.0% or less.

10. The reflective mask blank for EUV lithography according to claim 1 or 2, wherein the conductive film has a light transmittance of 1.0% or more at a wavelength of 1000 to 1100 nm, a light transmittance of 1.0% or more at a wavelength of 600 to 700 nm, and a light transmittance of less than 1.0% at a wavelength of 400 to 500 nm.

11. The reflective mask blank for EUV lithography according to claim 1 or 2, wherein the surface hardness of the conductive film is 10.0 GPa or more.

12. An upper layer is further provided on the conductive film. The reflective mask blank for EUV lithography according to claim 1 or 2, wherein the upper layer contains chromium (Cr) and at least one element selected from the group consisting of nitrogen (N) and oxygen (O).

13. The reflective mask blank for EUV lithography according to claim 1 or 2, wherein the surface roughness (Rq) of the conductive film is 0.600 nm or less.

14. A substrate with a conductive film, having a conductive film on the substrate. The conductive film contains at least one of nitrogen (N) and boron (B). The total content of N and B contained in the conductive film is more than 0 at%, and 65 at% or less. The refractive index n of the conductive film at a wavelength of 1000 to 1100 nm λ１０００－１１００ｎｍ is 5.300 or less, and the attenuation coefficient k λ１０００－１１００ｎｍ is 5.200 or less, The refractive index n of the conductive film at a wavelength of 600 to 700 nm λ６００－７００ｎｍ is 4.300 or less, and the extinction coefficient k λ６００－７００ｎｍ is 4.500 or less, The refractive index n of the conductive film at a wavelength of 480 to 500 nm λ４８０－５００ｎｍ is 2.500 or more, and the extinction coefficient k λ４８０－５００ｎｍ is 0.440 or more, The film thickness t of the conductive film is 20 to 350 nm. The resistivity of the conductive film is 3.5 mΩ·cm or less. The sheet resistance value of the conductive film is 0.1 Ω / □ or more and 250 Ω / □ or less. A substrate with a conductive film.

15. The substrate with a conductive film according to claim 14, wherein the conductive film contains at least one of tantalum (Ta) and chromium (Cr).

16. The substrate with a conductive film according to claim 14 or 15, wherein the conductive film contains Ta and N.

17. The substrate with a conductive film according to claim 16, wherein the conductive film contains N in an amount of more than 0 at% and 65 at% or less.

18. The substrate with a conductive film according to claim 14 or 15, wherein the conductive film contains Ta and B.

19. The substrate with a conductive film according to claim 18, wherein the conductive film contains B in an amount of more than 0 at% and 35 at% or less.

20. The substrate with a conductive film according to claim 14 or 15, wherein the resistivity of the conductive film is 0.050 mΩ·cm or more and 3.5 mΩ·cm or less.

21. The conductive film contains Ta, and in the diffraction peaks derived from the conductive film observed by the out of plane XRD method, the full width at half maximum (FWHM) of the diffraction peak attributed to the bcc (110) plane of Ta is 1.5 to 4.0°, the substrate with a conductive film according to claim 14 or 15.

22. The conductive film has a light transmittance of 1.0% or more at a wavelength of 1000 to 1100 nm, a light transmittance of 1.0% or more at a wavelength of 600 to 700 nm, and a light transmittance of 1.0% or less at a wavelength of 400 to 500 nm, the substrate with a conductive film according to claim 14 or 15.

23. The conductive film has a light transmittance of 1.0% or more at a wavelength of 1000 to 1100 nm, a light transmittance of 1.0% or more at a wavelength of 600 to 700 nm, and a light transmittance of less than 1.0% at a wavelength of 400 to 500 nm, the substrate with a conductive film according to claim 14 or 15.

24. The surface hardness of the conductive film is 10.0 GPa or more, the substrate with a conductive film according to claim 14 or 15.

25. An upper layer is further provided on the conductive film, The upper layer contains chromium (Cr) and at least one element selected from the group consisting of nitrogen (N) and oxygen (O), the substrate with a conductive film according to claim 14 or 15.

26. The surface roughness (Rq) of the conductive film is 0.600 nm or less, the substrate with a conductive film according to claim 14 or 15.

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