Reflective mask blank for EUV lithography, reflective mask for EUV lithography, and method for manufacturing them

Abstract

To provide an EUV mask blank that has a phase shift film having amorphous crystal structure.SOLUTION: Provided is a reflection type mask blank 1a for EUV lithography in which a multilayer reflection coating 12 that reflects EUV light and a phase shift coating 14 that shifts the phase of the EUV light are formed in this order on a substrate 11, and in which the phase shift coating has a layer 1 containing ruthenium (Ru) and at least one selected from the group consisting of oxygen (O) and nitrogen (N), and among the diffraction peaks derived from the phase shift film observed at 2θ: 20° to 50° in the out_of_plane_XRD method, the half-value width FWHM of the highest intensity peak is 1.0° or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a reflective mask blank for EUV (Extreme Ultra Violet) lithography used in semiconductor manufacturing etc. (hereinafter, in this specification, referred to as "EUV mask blank"), a reflective mask for EUV lithography (hereinafter, in this specification, referred to as "EUV mask"), and manufacturing methods thereof.

Background Art

[0002] Conventionally, in the semiconductor industry, as a fine pattern transfer technology necessary for forming an integrated circuit composed of fine patterns on an Si substrate etc., 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 using the immersion method, it is said to be about 1 / 4 of the exposure wavelength, and even when using the immersion method of an ArF laser (193 nm), about 20 nm to 30 nm is expected to be the limit. Therefore, as an exposure technology after 20 nm to 30 nm, EUV lithography of an exposure technology 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 vacuum ultraviolet region. Specifically, it refers to light rays with a wavelength of about 10 nm 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. The phase shift mask gives a 180-degree phase difference to the light transmitted through the transmission parts of the mask pattern by making the transmission parts of the mask pattern different in substance or shape from adjacent transmission parts. Therefore, in the region between both transmission parts, the transmitted diffracted lights with 180-degree different phases 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 the best in principle for the phase difference, if it is substantially about 175 degrees to 185 degrees, the resolution improvement effect can be sufficiently obtained.

[0005] A halftone mask, which is a type of phase shift mask, uses a semi-transmissive thin film for the light exposure as the absorption layer for the material constituting the mask pattern, attenuates the transmittance to about several percent (usually about 2.5% to 15.0% with respect to the substrate transmitted light), and gives a phase difference of about 175 degrees to 185 degrees with the normal substrate transmitted light, thereby improving the resolution of the pattern edge part and the transfer accuracy.

[0006] EUV exposure uses a reflective optical system, and has a small NA (numerical aperture) and a short wavelength. Therefore, as a specific problem, it is easily affected by the surface unevenness of mirrors and masks, and it is not easy to accurately resolve the target fine line width. For this reason, a halftone EUV mask has been proposed that can apply the principle of the halftone mask used in conventional excimer laser exposure etc. also to EUV exposure using a reflective optical system (see, for example, Patent Documents 1 and 2).

[0007] In Patent Documents 1 and 2, as the phase shift film, a layer containing Ru with a small refractive index n is used to reduce the film thickness for obtaining a predetermined phase difference, and to enable the formation of a finer and higher-precision phase shift pattern.

[0008] However, since RuO described in Patent Document 1 and Ru described in Patent Document 2 are materials that are prone to crystallization, there is a concern that crystal particles may adversely affect the pattern shape when forming a phase shift film pattern. If the crystallinity of the material constituting the phase shift film is high, there are problems such as a large surface roughness of the phase shift film and a large line edge roughness (LER) after patterning. Therefore, it is preferable that the crystal structure of the phase shift film is amorphous.

[0009] Therefore, in Patent Document 3, it is stated that by using a material containing Ru and a predetermined element for the phase shift film, the crystal structure of the phase shift film can be made amorphous, and the adverse effects during the formation of the phase shift pattern by crystal particles such as metals can be reduced.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0011] However, it has been found that even when a material containing Ru and a predetermined element is used for the phase shift film according to the invention described in Patent Document 3, the crystal structure of the phase shift film may not become amorphous.

[0012] An object of the present invention is to provide an EUV mask blank including a phase shift film having an amorphous crystal structure in order to solve the above-mentioned problems of the prior art.

Means for Solving the Problems

[0013] The present invention is as follows in [1] to

[16] . [1] A reflective mask blank for EUV lithography, in which a multilayer reflective film that reflects EUV light and a phase shift film that shifts the phase of EUV light are formed in this order on a substrate, wherein the phase shift film has a layer 1 containing ruthenium (Ru) and at least one selected from the group consisting of oxygen (O) and nitrogen (N), A reflective mask blank for EUV lithography, characterized in that, in the diffraction peaks derived from the phase shift film observed at 2θ: 20° to 50° by the out-of-plane XRD method, the full width at half maximum FWHM of the peak with the highest intensity is 1.0° or more. [2] The reflective mask blank for EUV lithography according to [1], wherein the layer 1 contains Ru in the range of 40 to 99 at%, O in the range of 1 to 60 at%, or Ru in the range of 30 to 98 at%, O in the range of 1 to 69 at%, and N in the range of 1 to 69 at%. [3] The reflective mask blank for EUV lithography according to [1], wherein the layer 1 contains Ru in the range of 30 to 98 at% and N in the range of 2 to 70 at%. [4] The reflective mask blank for EUV lithography according to [1], wherein the layer 1 further contains at least one element (X) selected from the group consisting of chromium (Cr), tantalum (Ta), titanium (Ti), rhenium (Re), tungsten (W), bismuth (Bi), manganese (Mn), platinum (Pt), copper (Cu), iridium (Ir), and vanadium (V), in a composition ratio (at%) of Ru to X (Ru:X) in the range of 20:1 to 1:5, and the total of Ru and X (Ru + X) is in the range of 40 to 99 at%, and O is in the range of 1 to 60 at%, or the total of Ru and X (Ru + X) is in the range of 30 to 98 at%, O is in the range of 1 to 69 at%, and N is in the range of 1 to 69 at%. [5] The reflective mask blank for EUV lithography according to [3], wherein the layer 1 further contains at least one element (X) selected from the group consisting of Cr, Ta, Ti, Re, W, Bi, Mn, Pt, Cu, Ir, and V, in a composition ratio (at%) of Ru to X (Ru:X) in the range of 20:1 to 1:5, and the total of Ru and X (Ru + X) is in the range of 30 to 90 at%, and N is in the range of 10 to 70 at%. [6] The reflective mask blank for EUV lithography according to any one of [1] to [5], wherein the phase shift film further has a layer 2 containing at least one element (X) selected from the group consisting of Cr, Ta, Ti, Re, W, Bi, Mn, Pt, Cu, Ir, and V. [7] The reflective mask blank for EUV lithography according to [6], wherein the layer 2 further contains at least one element selected from the group consisting of O, N, boron (B), and carbon (C). [8] The reflective mask blank for EUV lithography according to any one of [1] to [7], wherein the film thickness of the phase shift film is 20 nm to 60 nm. [9] The reflective mask blank for EUV lithography according to any one of [1] to [8], wherein the thickness of the layer 1 is 10 nm or more.

[10] The reflective mask blank for EUV lithography according to any one of [1] to [9], wherein the phase difference between the reflected light of EUV light from the multilayer reflective film and the reflected light of EUV light from the phase shift film is 150 degrees to 250 degrees, and the relative reflectance ((reflectance of EUV light on the surface of the phase shift film / reflectance of EUV light on the surface of the multilayer reflective film) × 100) between the reflectance of EUV light on the surface of the phase shift film and the reflectance of EUV light on the surface of the multilayer reflective film is 2% to 37%.

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

[10] , wherein a protective film of the multilayer reflective film is formed between the multilayer reflective film and the phase shift film.

[12] The reflective mask blank for EUV lithography according to

[11] , wherein the protective film contains at least one element selected from the group consisting of Ru, palladium (Pd), Ir, rhodium (Rh), Pt, zirconium (Zr), niobium (Nb), Ta, Ti, and silicon (Si).

[13] The reflective mask blank for EUV lithography according to

[12] , wherein the protective film further contains at least one element selected from the group consisting of O, N, and B.

[14] On the phase shift film, there is an etching mask film, and the etching mask film contains at least one element selected from the group consisting of Nb, Ti, molybdenum (Mo), Ta, and Si. The reflective mask blank for EUV lithography described in [1] to

[13] .

[15] The etching mask film further contains at least one element selected from the group consisting of O, N, and B. The reflective mask blank for EUV lithography described in

[14] .

[16] A reflective mask for EUV lithography in which a pattern is formed on the phase shift film of the reflective mask blank for EUV lithography described in [1] to

[15] .

[17] A step of forming a multilayer reflective film that reflects EUV light on a substrate, A step of forming a phase shift film that shifts the phase of EUV light on the multilayer reflective film, A step of forming an etching mask film on the phase shift film including The phase shift film has a layer 1 containing ruthenium (Ru) and at least one selected from the group consisting of oxygen (O) and nitrogen (N), In the out-of-plane XRD method, among the diffraction peaks derived from the phase shift film observed at 2θ: 20° to 50°, the full width at half maximum FWHM of the peak with the highest intensity is 1.0° or more, The manufacturing method of the reflective mask blank for EUV lithography, characterized in that the etching mask film can be removed by cleaning with an acid or a base.

[18] A method for manufacturing a reflective mask for EUV lithography, characterized in that a pattern is formed by patterning the phase shift film in the reflective mask blank for EUV lithography manufactured by the manufacturing method described in

[17] .

Effect of the Invention

[0014] The EUV mask blank of the present invention includes a phase shift film having an amorphous crystal structure.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0016] Hereinafter, the EUV mask blank of the present invention and the EUV mask of the present invention will be described with reference to the drawings.

[0017] FIG. 1 is a schematic cross-sectional view showing one embodiment of the EUV mask blank of the present invention. The EUV mask blank 1a shown in FIG. 1 includes a multilayer reflective film 12 that reflects EUV light on a substrate 11, a protective film 13 of the multilayer reflective film 12, and a phase shift film 14 that shifts the phase of the EUV light, which are formed in this order. However, in the EUV mask blank of the present invention, among the configurations shown in FIG. 1, only the substrate 11, the multilayer reflective film 12, and the phase shift film 14 are essential, and the protective film 13 is an optional component. Note that the protective film 13 of the multilayer reflective film 12 is a layer provided for the purpose of protecting the multilayer reflective film 12 during the pattern formation of the phase shift film 14.

[0018] Hereinafter, each component of the EUV mask blank 1a will be described.

[0019] 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 (specifically, the coefficient of thermal expansion at 20 ° C is preferably 0 ± 0.05 × 10 -7 / ° C, more preferably 0 ± 0.03 × 10 -7 / ° C), and is excellent in smoothness, flatness, and resistance to cleaning liquids used for cleaning the mask blank or the photomask after pattern formation. Specifically, as the substrate 11, glass having a low coefficient of thermal expansion, such as SiO 2 -TiO 2 -based glass, etc. are used, but it is not limited thereto, and substrates such as crystallized glass in which β-quartz solid solution is precipitated, quartz glass, silicon, and metal can also be used. The substrate 11 preferably has a smooth surface with a surface roughness (rms) 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. The size, thickness, etc. of the substrate 11 are appropriately determined according to the design values of the mask, etc. In the examples shown later, SiO having an outer shape of 6 inches (152 mm) square and a thickness of 0.25 inches (6.3 mm) 2 -TiO 2 -based glass was used. It is preferable that there are no defects on the surface of the substrate 11 on the side where the multilayer reflective film 12 is formed. However, even if there are defects, as long as no phase defects are 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 defects 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.

[0020] The multilayer reflective film 12 achieves high EUV light reflectivity by alternately laminating a plurality of high refractive index layers and low refractive index layers multiple times. In the multilayer reflective film 12, 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, and Si / Ru / Mo / Ru multilayer reflective film can also be used.

[0021] The multilayer reflective film 12 is not particularly limited as long as it has desired characteristics as a reflective layer of the EUV mask blank. Here, the characteristic particularly required for the multilayer reflective film 12 is high EUV light reflectivity. Specifically, when irradiating the surface of the multilayer reflective film 12 with light in the wavelength region of EUV light at an incident angle of 6 degrees, it is preferable that the maximum value of the light reflectivity near a wavelength of 13.5 nm is 60% or more, and more preferably 65% or more. Also, even when a protective film 13 is provided on the multilayer reflective film 12, it is preferable that the maximum value of the light reflectivity near a wavelength of 13.5 nm is 60% or more, and more preferably 65% or more.

[0022] The film thickness of each layer constituting the multilayer reflective film 12 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, to obtain a multilayer reflective film 12 with 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.

[0023] Note that each layer constituting the multilayer reflective film 12 may be formed to a desired thickness using a well-known film-forming method such as the magnetron sputtering method or the 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 Pa to 2.7×10 -2 Pa) is used. A Si film is formed to a thickness of 4.5 nm at an ion acceleration voltage of 300 V to 1500 V and a film-forming rate of 0.030 nm / sec to 0.300 nm / sec. Next, a Mo target is used as the target, and Ar gas (gas pressure 1.3×10 -2 Pa to 2.7×10 -2 Pa) is used. A Mo film is preferably formed to a thickness of 2.3 nm at an ion acceleration voltage of 300 V to 1500 V and a film-forming rate of 0.030 nm / sec 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.

[0024] In order to prevent oxidation of the surface of the multilayer reflective film 12, it is preferable that the outermost layer of the multilayer reflective film 12 be a layer of a material that is difficult to oxidize. The layer of a material that is difficult to oxidize functions as a cap layer for the multilayer reflective film 12. A specific example of the layer of a material that is difficult to oxidize and functions as a cap layer is a Si layer. When the multilayer reflective film 12 is a Si / Mo multilayer reflective film, by making the outermost layer a Si layer, the outermost layer functions as a cap layer. In that case, the film thickness of the cap layer is preferably 11 ± 2 nm.

[0025] The protective film 13 is provided for the purpose of protecting the multilayer reflective film 12 so that the multilayer reflective film 12 is not damaged by the etching process when patterning the phase shift film 14 by an etching process, usually a dry etching process. Therefore, as the material of the protective film, a material that is less affected by the etching process of the phase shift film 14, that is, a material whose etching rate is slower than that of the phase shift film 14 and is less likely to be damaged by this etching process is selected. To satisfy the above characteristics, the protective film 13 contains at least one element selected from the group consisting of Ru, Pt, Pd, Ir, Rh, Zr, Nb, Ta, Ti, and Si. However, since Ru is also a constituent material of the phase shift film 14, when Ru is used as the material of the protective film 13, an alloy with other elements is used. A specific example is RuZr. The protective film 13 may further contain at least one element selected from the group consisting of O, N, and B. That is, it may be an oxide, nitride, oxynitride, or boride of the above elements. Specific examples include ZrO 2 , SiO 2 .

[0026] The thickness of the protective film 13 is not particularly limited, but in the case of a RuZr film, 2 nm to 3 nm is preferable.

[0027] The protective film 13 is formed using a well-known film formation method such as a magnetron sputtering method or an ion beam sputtering method. For example, when forming a RuZr film using a DC sputtering method, a Ru target and a Zr target are used as targets, and Ar gas (gas pressure 1.0×10 -2 Pa or more and 1.0×10 0 Pa or less) is used, and the input power to the Ru target and the Zr target is 100 W or more and 600 W or less, and it is preferable to form a film with a film formation rate of 0.020 nm / sec to 1.000 nm / sec so that the thickness is 2 nm to 3 nm.

[0028] As described above, the phase shift film in the halftone type EUV mask is required to have an amorphous crystal structure.

[0029] In the EUV mask blank 1a of the present invention, the phase shift film 14 has a layer 1 containing Ru and at least one selected from the group consisting of O and N. In the EUV mask blank 1a of the present invention, since the phase shift film 14 has the layer 1, in the diffraction peak derived from the phase shift film 14 observed at 2θ: 20° to 50° by the out-of-plane XRD method, the full width at half maximum FWHM (hereinafter, referred to as the full width at half maximum FWHM in this specification) of the peak with the highest intensity is 1.0° or more. When the full width at half maximum FWHM is 1.0° or more, a sharp peak derived from the crystal phase is not observed, and the crystal structure of the phase shift film 14 is amorphous. When the phase shift film 14 is composed only of the layer 1, the crystal structure of the phase shift film 14 forming the layer 1 is amorphous. When the phase shift film 14 has a layer 2 described later, the crystal structure of the entire phase shift film 14 including the layer 1 and the layer 2 is amorphous. In addition, when no diffraction peak derived from the phase shift film is observed at 2θ: 20° to 50° by the out-of-plane XRD method, the full width at half maximum FWHM is set to 180°.

[0030] When the crystal structure of the phase shift film 14 is amorphous, the smoothness of the surface of the phase shift film 14 is increased. In this specification, as an index of the smoothness of the surface of the phase shift film 14, the surface roughness (RMS) of the surface of the phase shift film 14 measured using an atomic force microscope (Atomic Force Microscope) is used. In the EUV mask blank 1a of the present invention, the surface roughness (RMS) of the surface of the phase shift film 14 is preferably 0.3 nm or less, and more preferably 0.25 nm or less.

[0031] In the phase shift film 14 in the present invention, the full width at half maximum FWHM is preferably 2.0° or more, and more preferably 3.0° or more.

[0032] In the EUV mask blank 1a of the present invention, when the phase shift film 14 is in the first to third modes shown below, the full width at half maximum FWHM is 1.0° or more.

[0033] First Aspect The first mode of the phase shift film 14 has a layer 1 containing Ru in the range of 40 to 99 at% and O in the range of 1 to 60 at%. When the O content of layer 1 is less than 1 at%, when measured by the out-of-plane XRD method, a sharp peak derived from the crystal phase of Ru is observed in the diffraction peak derived from the phase shift film 14 observed at 2θ: 20° to 50°, and the full width at half maximum FWHM becomes less than 1.0°. When the O content of layer 1 exceeds 60 at%, a sharp peak derived from the crystal phase of RuO 2 is observed in the diffraction peak derived from the phase shift film 14 observed at 2θ: 20° to 50°, and the full width at half maximum FWHM becomes less than 1.0°. When the O content of the Ru-containing layer is in the range of 1 to 60 at%, when measured by the out-of-plane XRD method, a sharp peak derived from the crystal phase of Ru or RuO 2 is not observed in the diffraction peak derived from the phase shift film 14 observed at 2θ: 20° to 50°, and the full width at half maximum FWHM becomes 1.0° or more.

[0034] In this specification, the content of each element in layer 1 of the phase shift film and layer 2 described later is a measured value by an X-ray photoelectron spectrometer.

[0035] When forming the phase shift film by sputtering according to the procedure described later, O may be mixed in, but the O content due to such mixing is less than 1.0 at%, and the full width at half maximum FWHM does not become 1.0° or more.

[0036] In the first mode of the phase shift film 14, since the optical constant of layer 1 changes due to the introduction of O, the EUV light reflectance on the surface of the phase shift film can be adjusted by controlling the O content of layer 1.

[0037] The first aspect of the phase shift film 14 preferably has a layer 1 containing Ru in the range of 40 to 90 at% and O in the range of 10 to 60 at%, and more preferably has a layer 1 containing Ru in the range of 40 to 75 at% and O in the range of 25 to 60 at%.

[0038] Second Aspect The second aspect of the phase shift film 14 has a layer 1 containing Ru in the range of 30 to 98 at%, O in the range of 1 to 69 at%, and N in the range of 1 to 69 at%. When the O content of layer 1 is less than 1 at%, when measured by the out-of-plane XRD method, a sharp peak derived from the crystal phase of Ru is observed in the diffraction peaks derived from the phase shift film 14 observed at 2θ: 20° to 50°, and the full width at half maximum FWHM is less than 1.0°. When the O content of layer 1 exceeds 69 at%, it is difficult to form layer 1. When the N content of layer 1 is less than 1 at%, when measured by the out-of-plane XRD method, a sharp peak derived from the crystal phase of Ru is observed in the diffraction peaks derived from the phase shift film 14 observed at 2θ: 20° to 50°, and the full width at half maximum FWHM is less than 1.0°. When the N content of layer 1 exceeds 69 at%, it is difficult to form layer 1. When the O content of the layer containing Ru is in the range of 1 to 69 at% and the N content is in the range of 1 to 69 at%, when measured by the out-of-plane XRD method, a sharp peak derived from the crystal phase of Ru is not observed in the diffraction peaks derived from the phase shift film 14 observed at 2θ: 20° to 50°, and the full width at half maximum FWHM is 1.0° or more.

[0039] In the second aspect of the phase shift film 14, since the optical constants of layer 1 change due to the introduction of O, it is possible to adjust the EUV light reflectivity on the surface of the phase shift film by controlling the O content of layer 1.

[0040] The second aspect of the phase shift film 14 preferably has a layer 1 containing Ru in the range of 30 to 75 at%, O in the range of 24 to 69 at%, and N in the range of 1 to 20 at%, and more preferably has a layer 1 containing Ru in the range of 30 to 65 at%, O in the range of 34 to 69 at%, and N in the range of 1 to 10 at%.

[0041] Third Aspect The third aspect of the phase shift film 14 has a layer 1 containing Ru in the range of 30 to 98 at% and N in the range of 2 to 70 at%. When the N content of layer 1 is less than 2 at%, when measured by the out-of-plane XRD method, a sharp peak derived from the crystal phase of Ru is observed in the diffraction peaks derived from the phase shift film 14 observed at 2θ: 20° to 50°, and the full width at half maximum FWHM is less than 1.0°. When the N content of layer 1 exceeds 70 at%, it is difficult to form layer 1. When the N content of layer 1 is in the range of 2 to 70 at%, when measured by the out-of-plane XRD method, a sharp peak derived from the crystal phase of Ru is not observed in the diffraction peaks derived from the phase shift film 14 observed at 2θ: 20° to 50°, and the full width at half maximum FWHM is 1.0° or more.

[0042] In the third aspect of the phase shift film 14, since the change in the optical constants of layer 1 due to the introduction of N is small, the EUV light reflectivity on the surface of the phase shift film is hardly affected by the N content. Therefore, by introducing N, the crystal structure of the phase shift film 14 can be made amorphous without significantly changing the EUV light reflectivity on the surface of the phase shift film.

[0043] The third aspect of the phase shift film 14 preferably has a layer 1 containing Ru in the range of 80 to 98 at% and N in the range of 2 to 20 at%.

[0044] The first, second, and third embodiments of the phase shift film 14 are such that, for the purpose of adjusting the EUV light reflectance on the surface of the phase shift film 14, layer 1 may further contain at least one element (X) selected from the group consisting of chromium (Cr), tantalum (Ta), titanium (Ti), rhenium (Re), tungsten (W), bismuth (Bi), manganese (Mn), platinum (Pt), copper (Cu), iridium (Ir), and vanadium (V). As X, Cr, Re, Mn, and V are preferred, and Cr and Re are more preferred.

[0045] In the first, second, and third embodiments of the phase shift film 14, when layer 1 contains element (X), it contains element (X) in a composition ratio (at%) of Ru to X (Ru:X) in the range of 20:1 to 1:5 in layer 1. When the content ratio of element (X) in layer 1 is more than 20:1 in the composition ratio (Ru:X), the effect of adjusting the EUV light reflectance on the surface of the phase shift film 14 due to the inclusion of element (X) is exerted. On the other hand, when the content ratio of element (X) in layer 1 is less than 1:5 in the composition ratio (Ru:X), the film thickness required to obtain a predetermined phase difference can be reduced. The content ratio of element (X) in layer 1 is preferably in the range of 4:1 to 1:4 in the composition ratio (Ru:X), and more preferably in the range of 2:1 to 1:2.

[0046] In the first embodiment of the phase shift film 14, when layer 1 contains element (X), it contains the total of Ru and X (Ru + X) in the range of 40 to 99 at%, and O in the range of 1 to 60 at%, preferably contains Ru + X in the range of 50 to 99 at%, and O in the range of 1 to 50 at%, and more preferably contains Ru + X in the range of 80 to 99 at%, and O in the range of 1 to 20 at%.

[0047] In the second embodiment of the phase shift film 14, when layer 1 contains element (X), it contains the total of Ru and X (Ru + X) in the range of 30 to 98 at%, O in the range of 1 to 69 at%, and N in the range of 1 to 69 at%, preferably contains Ru + X in the range of 50 to 98 at%, O in the range of 1 to 30 at%, and N in the range of 1 to 20 at%, and more preferably contains Ru + X in the range of 70 to 98 at%, O in the range of 1 to 20 at%, and N in the range of 1 to 10 at%.

[0048] In the third aspect of the phase shift film 14, when layer 1 contains element (X), the total of Ru and X (Ru + X) is preferably in the range of 30 to 90 at%, N is in the range of 10 to 70 at%, Ru + X is in the range of 60 to 90 at%, and N is in the range of 10 to 40 at%.

[0049] In the phase shift film 14, when layer 1 contains two or more elements as element (X), X in the composition ratio (Ru:X) and the total of Ru and X (Ru + X) represents the total of two or more elements.

[0050] The phase shift film 14 may be configured by laminating two or more of layer 1 in the first, second, and third aspects. When the phase shift film 14 is configured by laminating two or more of layer 1 in the first, second, and third aspects, some layers may contain element (X), or all layers may contain element (X). When two or more layers contain element (X), the element (X) contained in each layer may be the same or different.

[0051] The phase shift film 14 may further have a layer 2 containing at least one element (X) selected from the group consisting of Cr, Ta, Ti, Re, W, Bi, Mn, Pt, Cu, Ir, and V. As the element (X), Cr, Ta, Pt, and Ir are preferred, and Cr and Ta are more preferred. Layer 2 may further contain at least one element selected from the group consisting of O, N, B, and C. Note that layer 2 does not contain Ru.

[0052] The phase shift film 14 may have two or more layer 2s with different contained elements.

[0053] By having the phase shift film 14 include the layer 2, the EUV light reflectance can be adjusted. However, if the thickness of the layer 2 is too thick, the reflectance will become too small. Therefore, the relative ratio of the thicknesses of the layer 1 and the layer 2 ((thickness of layer 1):(thickness of layer 2)) is preferably in the range of 1:1 to 30:1, and more preferably in the range of 5:1 to 20:1. In addition, when the phase shift film 14 includes two or more layer 1s, the thickness of the layer 1 described above is the total film thickness of two or more layer 1s. When the phase shift film 14 includes two or more layer 2s, the thickness of the layer 2 described above is the total film thickness of two or more layer 2s.

[0054] When the phase shift film 14 has the layer 2, the arrangement of the layer 1 and the layer 2 in the phase shift film 14 is not particularly limited. The layer 2 may be formed on the layer 1, or the layer 1 may be formed on the layer 2.

[0055] The layer 1 in the first aspect, the second aspect, and the third aspect of the phase shift film 14 can be formed using a well-known film formation method such as a magnetron sputtering method or an ion beam sputtering method.

[0056] For example, when forming the layer 1 in the first aspect of the phase shift film 14 using a reactive sputtering method, a Ru target is used as the target, and a mixed gas containing an inert gas and O 2 is used as the sputtering gas, and it may be carried out under the following film formation conditions. Sputtering gas: A mixed gas of Ar gas and O 2 (The volume ratio of O 2 gas in the mixed gas (O 2 / (Ar + O 2 )) = 0.010 to 0.50, preferably 0.010 to 0.30, more preferably 0.010 to 0.200. Gas pressure 5 × 10 -2 Pa to 1.0 Pa, preferably 1 × 10 -1 Pa to 8 × 10 -1 Pa, more preferably 2 × 10 -1 Pa to 4 × 10 -1 Pa.) Input power density per target area: 1.0 W / cm 2 ~15.0 W / cm2 Preferably 3.0 W / cm 2 ~12.0 W / cm 2 More preferably 4.0 W / cm 2 ~10.0 W / cm 2 Film formation rate: 0.010 nm / sec to 1.00 nm / sec, preferably 0.015 nm / sec to 0.500 nm / sec, more preferably 0.020 nm / sec to 0.300 nm / sec.

[0057] For example, when forming the layer 1 of the second aspect of the phase shift film 14 using the reactive sputtering method, as the target, a Ru target is used, and as the sputtering gas, O 2 and N 2 mixed gas, or an inert gas and O 2 and N 2 mixed gas containing the same may be used and carried out under the following film formation conditions. Sputtering gas: Mixed gas of Ar gas and O 2 and N 2 (Volume ratio of O 2 gas in the mixed gas (O 2 / (Ar + O 2 + N 2 )) = 0.010 to 0.75, preferably 0.010 to 0.500, more preferably 0.010 to 0.200. Volume ratio of N 2 gas in the mixed gas (N 2 / (Ar + O 2 + N 2 )) = 0.010 to 0.75, preferably 0.010 to 0.500, more preferably 0.010 to 0.200. Gas pressure 5 × 10 -2 Pa to 1 × 1.0 Pa, preferably 1 × 10 -1 Pa to 8 × 10 -1 Pa, more preferably 2 × 10 -1 Pa to 4 × 10 -1 Pa.). Input power density per target area: 1.0 W / cm 2 ~15.0 W / cm 2 Preferably 3.0 W / cm 2 ~12.0 W / cm 2 More preferably 4.0 W / cm 2 ~10.0 W / cm2 Film formation rate: 0.010 nm / sec to 1.000 nm / sec, preferably 0.015 nm / sec to 0.500 nm / sec, more preferably 0.020 nm / sec to 0.300 nm / sec.

[0058] For example, when forming the layer 1 of the third aspect of the phase shift film 14 using the reactive sputtering method, a Ru target is used as the target, and N 2 gas, or a mixed gas containing an inert gas and N 2 can be used and implemented under the following film formation conditions. Sputtering gas: N 2 gas, or a mixed gas of Ar gas and N 2 (volume ratio of N 2 gas in the sputtering gas (N 2 / (Ar + N 2 )) = 0.100 to 1.000, preferably 0.200 to 0.750, more preferably 0.250 to 0.500. Gas pressure 5 × 10 -2 Pa to 1.0 Pa, preferably 1 × 10 -1 Pa to 8 × 10 -1 Pa, more preferably 2 × 10 -1 Pa to 4 × 10 -2 Pa.) Input power density per target area: 1.0 W / cm 2 to 15.0 W / cm 2 , preferably 3.0 W / cm 2 to 12.0 W / cm 2 , more preferably 4.0 W / cm 2 to 10.0 W / cm 2 Film formation rate: 0.010 nm / sec to 1.000 nm / sec, preferably 0.015 nm / sec to 0.500 nm / sec, more preferably 0.020 nm / sec to 0.300 nm / sec.

[0059] When the phase shift film 14 includes the layer 2, the layer 2 can be formed using a well-known film formation method such as the magnetron sputtering method or the ion beam sputtering method.

[0060] For example, when forming a layer 2 containing Ta as element X and also containing O and N using a reactive sputtering method, a Ta target is used as the target, and as the sputtering gas, O 2 and N 2 mixed gas, or an inert gas and O 2 and N 2 mixed gas containing the same can be used and carried out under the following film formation conditions. Sputtering gas: O 2 gas and N 2 mixed gas, or Ar gas and O 2 and N 2 mixed gas (volume ratio of O 2 gas in the mixed gas (O 2 / ((O 2 +N 2 )) or (Ar + O 2 +N 2 )) = 0.010 to 0.750, preferably 0.100 to 0.500, more preferably 0.200 to 0.500. Volume ratio of N 2 gas in the mixed gas (N 2 / ((O 2 +N 2 ) or (Ar + O 2 +N 2 )) = 0.010 to 0.750, preferably 0.010 to 0.500, more preferably 0.010 to 0.200. Gas pressure 5 × 10 -2 Pa to 1 × 1.0 Pa, preferably 1 × 10 -1 Pa to 8 × 10 -1 Pa, more preferably 2 × 10 -1 Pa to 4 × 10 -1 Pa.). Input power density per target area: 1.0 W / cm 2 to 15.0 W / cm 2 , preferably 3.0 W / cm 2 to 12.0 W / cm 2 , more preferably 4.0 W / cm 2 to 10.0 W / cm 2 . Film formation rate: 0.010 nm / sec to 1.000 nm / sec, preferably 0.015 nm / sec to 0.500 nm / sec, more preferably 0.020 nm / sec to 0.300 nm / sec

[0061] For example, when forming a layer 2 containing Cr and N as element X using a reactive sputtering method, a Cr target is used as the target, and N 2 gas, or a mixed gas containing an inert gas and N 2 may be used and carried out under the following film formation conditions. Sputtering gas: N 2 gas, or a mixed gas of Ar gas and N 2 (volume ratio of N 2 gas in the sputtering gas (N 2 / (Ar + N 2 )) = 0.100 to 1.000, preferably 0.200 to 0.750, more preferably 0.250 to 0.500. Gas pressure 5 × 10 -2 Pa to 1.0 Pa, preferably 1 × 10 -1 Pa to 8 × 10 -1 Pa, more preferably 2 × 10 -1 Pa to 4 × 10 -2 Pa.) Input power density per target area: 1.0 W / cm 2 to 15.0 W / cm 2 , preferably 3.0 W / cm 2 to 12.0 W / cm 2 , more preferably 4.0 W / cm 2 to 10.0 W / cm 2 . Film formation rate: 0.010 nm / sec to 1.000 nm / sec, preferably 0.015 nm / sec to 0.500 nm / sec, more preferably 0.020 nm / sec to 0.300 nm / sec.

[0062] When using an inert gas other than Ar, the concentration of the inert gas is set to the same concentration range as the above-described Ar gas concentration. When using a plurality of types of inert gases, the total concentration of the inert gases is set to the same concentration range as the above-described Ar gas concentration.

[0063] In the EUV mask blank 1a, it is preferable that the thickness of the phase shift film 14 is 20 nm or more because desired optical characteristics can be achieved as the phase shift film of the halftone type EUV mask shown below. Also, it is preferable that the thickness of layer 1 in the phase shift film 14 is 10 nm or more because desired optical characteristics can be achieved as the phase shift film of the halftone type EUV mask shown below.

[0064] When the light reflectance near a wavelength of 13.5 nm when irradiating the surface of the phase shift film 14 with light rays in the wavelength region of EUV light at an incident angle of 6 degrees is defined as the EUV light reflectance of the phase shift film surface, and the light reflectance near a wavelength of 13.5 nm when irradiating the surface of the multilayer reflective film 12 with light rays in the wavelength region of EUV light at an incident angle of 6 degrees is defined as the EUV light reflectance of the multilayer reflective film surface, the relative reflectance ((EUV light reflectance of the phase shift film surface / EUV light reflectance of the multilayer reflective film surface) × 100) between the EUV light reflectance of the phase shift film surface and the EUV light reflectance of the multilayer reflective film surface is preferably 2% to 37%, more preferably 4% to 20%, and even more preferably 6% to 15%. Also, the phase difference between the reflected light of EUV light from the multilayer reflective film 12 and the reflected light of EUV light from the phase shift film 14 is preferably 150 degrees to 250 degrees, and more preferably 180 degrees to 230 degrees.

[0065] In the EUV mask blank 1a, it is more preferable that the thickness of the phase shift film 14 is 30 nm or more, and even more preferably 35 nm or more. It is more preferable that the thickness of layer 1 in the phase shift film 14 is 20 nm or more, and even more preferably 30 nm or more.

[0066] In the EUV mask blank 1a, it is preferable that the thickness of the phase shift film 14 is 60 nm or less because the projection effect is reduced. The use of the halftone type EUV mask is, in principle, an effective means for improving the resolution in EUV lithography. However, the optimum reflectance in the halftone type EUV mask also depends on the exposure conditions and the pattern to be transferred, and it is difficult to determine it unconditionally. Furthermore, since EUV exposure is reflective exposure, the incident light is not perpendicular but enters from a slightly oblique direction (usually about 6°), and becomes reflected light by the EUV mask. In the EUV mask, the phase shift film is processed as a pattern. However, since EUV light enters obliquely, a pattern shadow is generated. Therefore, depending on the incident direction and the pattern arrangement direction, a shift from the original pattern position occurs in the transfer resist pattern on the wafer formed by the reflected light. This is called the shadowing effect and is an issue in EUV exposure. To reduce the shadowing effect, it is necessary to shorten the length of the shadow. For this purpose, the height of the pattern should be made as low as possible. To lower the height of the pattern, it is necessary to make the phase shift film as thin as possible.

[0067] The phase shift film 14 in the EUV mask blank 1a preferably has a film thickness of 55 nm or less, more preferably 50 nm or less.

[0068] For pattern formation on layer 1 of the first, second, and third aspects of the phase shift film 14, O 2 or a mixed gas of O 2 and a halogen-based gas (chlorine-based gas, fluorine-based gas) is used as the etching gas for dry etching. When dry etching is performed using O 2 or a mixed gas of O 2 and a halogen-based gas (chlorine-based gas, fluorine-based gas) as the etching gas, it is preferably possible to etch at an etching rate of 10 nm / min or more. O 2 As the mixed gas of O 2 and a halogen-based gas, it contains 40 vol% or more and less than 100 vol% of O 2 , preferably 75 vol% to 90 vol%, and contains more than 0 vol% and 60 vol% or less, preferably 10 vol% to 25 vol% of a chlorine-based gas or a fluorine-based gas. As the chlorine-based gas, Cl 2 , SiCl 4 , CHCl 3 , CCl 4 , BCl3 Chlorine-based gases such as these and mixed gases thereof are used. As fluorine-based gases, CF 4 , CHF 3 , SF 6 , BF 3 , XeF 2 and other fluorine-based gases and mixed gases thereof are used.

[0069] In the first and second aspects of the phase shift film 14, layer 1 has, by introducing O, not only the effect of suppressing crystallization, but also O 2 , or O 2 and a mixed gas of a halogen-based gas (chlorine-based gas, fluorine-based gas) has the effect of increasing the etching rate during dry etching using it as an etching gas. When the O content in layer 1 is increased, etching can be performed at a rate up to more than twice that of a film containing only Ru, and an improvement in throughput can be expected.

[0070] Also, when layer 1 of the first, second, and third aspects of the phase shift film 14 contains an element (X), for pattern formation of the phase shift film, O 2 , or O 2 and dry etching using a mixed gas of a halogen-based gas (chlorine-based gas, fluorine-based gas) as an etching gas are used. At this time, by selecting an element (X) that forms a volatile oxide or an acid halide such as Cr, V, Mn, or Re, pattern formation with few deposits on the pattern sidewalls can be expected.

[0071] When the phase shift film 14 is composed of only layer 1, pattern formation of the phase shift film can be achieved only by dry etching using O 2 , or O 2 and a mixed gas of a halogen-based gas (chlorine-based gas, fluorine-based gas) as an etching gas, so the pattern formation process is simple.

[0072] When the phase shift film 14 has layer 1 and layer 2, pattern formation of the phase shift film can be achieved by performing dry etching stepwise using two or more types of etching gases as necessary. For example, when the phase shift film 14 has a layer 1 and a layer 2 containing Ta as the element (X), the layer 1 is O 2 or O 2 Dry etching is performed using a mixed gas of O and a halogen-based gas (chlorine-based gas, fluorine-based gas) as the etching gas, and the layer 2 is dry-etched using a halogen-based gas (chlorine-based gas, fluorine-based gas) as the etching gas, whereby a pattern of the phase shift film can be formed.

[0073] Further, when the layer 2 contains an element that forms a volatile oxide such as Cr, V, Mn, Re, or an acid halide, for the layer 1 and the layer 2, O 2 or O 2 The pattern of the phase shift film can be formed only by dry etching using a mixed gas of O and a halogen-based gas (chlorine-based gas, fluorine-based gas) as the etching gas. Therefore, even if the phase shift film 14 has the layer 1 and the layer 2, the pattern formation process does not become complicated, and the pattern of the phase shift film can be easily formed.

[0074] FIG. 2 is a schematic cross-sectional view showing another embodiment of the EUV mask blank of the present invention. The EUV mask blank 1b shown in FIG. 2 has a multilayer reflective film 12 that reflects EUV light, a protective film 13 of the multilayer reflective film 12, a phase shift film 14 that shifts the phase of the EUV light, and an etching mask film 15, which are formed in this order. Among the components of the EUV mask blank 1b, the substrate 11, the multilayer reflective film 12, the protective film 13, and the phase shift film 14 are the same as those of the above-described EUV mask blank 1a and are therefore omitted.

[0075] Generally, it is known that a resist can be thinned by providing a layer of a material (etch mask film) having resistance to the etching conditions of a phase shift film on the phase shift film. That is, by forming an etch mask film and reducing the relative rate (etch selectivity) of the etch rate of the etch mask film to 1 when the etch rate of the phase shift film under the etching conditions of the phase shift film is 1, the resist can be thinned.

[0076] The etch mask film 15 is required to have a sufficiently high etch selectivity under the etching conditions of the phase shift film 14. Therefore, the etch mask film 15 is O 2 or O 2 It is required to have high etching resistance to dry etching using a mixed gas of and a halogen-based gas (chlorine-based gas, fluorine-based gas) as the etching gas.

[0077] On the other hand, the etch mask film 15 is preferably removable with a cleaning solution using an acid or a base, which is used as a resist cleaning solution in EUV lithography. Specific examples of the cleaning solution used for the above purpose include sulfuric acid peroxide (SPM), ammonia peroxide, and hydrofluoric acid. SPM is a solution obtained by mixing sulfuric acid and hydrogen peroxide, and sulfuric acid and hydrogen peroxide can be mixed at a volume ratio of 4:1 to 1:3, preferably 3:1. At this time, the temperature of SPM is preferably controlled to 100 °C or higher from the viewpoint of improving the etching rate. Ammonia peroxide is a solution obtained by mixing ammonia and hydrogen peroxide, and NH 4 OH, hydrogen peroxide, and water can be mixed at a volume ratio of 1:1:5 to 3:1:5. At this time, the temperature of ammonia peroxide is preferably controlled at 70 °C to 80 °C.

[0078] To meet the above requirements, the etching mask film 15 of the EUV mask blank 1b of the present invention preferably contains at least one element selected from the group consisting of Nb, Ti, Mo, Ta, and Si. The etching mask film 15 may further contain at least one element selected from the group consisting of O, N, and B. That is, it may be an oxide, oxynitride, nitride, or boride of the above elements. Specific examples of the constituent material of the etching mask film 15 include, for example, Nb-based materials such as Nb, Nb 2 O 5 , and NbON. The etching mask film 15 made of these Nb-based materials can be etched by dry etching using a chlorine-based gas as the etching gas. Also, Mo-based materials such as Mo, MoO 3 , and MoON can be mentioned. The etching mask film 15 made of these Mo-based materials can be etched, for example, by dry etching using a chlorine-based gas as the etching gas. Further, Si-based materials such as Si, SiO 2 , Si 3 N 4 can be mentioned. The etching mask film 15 made of these Si-based materials can be etched, for example, by dry etching using a fluorine-based gas as the etching gas. When using a Si-based material as the etching mask film 15, removal using hydrofluoric acid as the cleaning liquid is preferable.

[0079] The film thickness of the etching mask film 15 is preferably 20 nm or less from the viewpoint of removability by the cleaning liquid. For the etching mask film 15 made of an Nb-based material, a film thickness of 5 nm to 15 nm is more preferable.

[0080] The etching mask film 15 can be formed by a known film formation method, for example, a magnetron sputtering method or an ion beam sputtering method.

[0081] When forming an NbN film by a sputtering method, a reactive sputtering method using a Nb target may be carried out in a gas atmosphere in which an inert gas containing at least one of He, Ar, Ne, Kr, and Xe (hereinafter simply referred to as an inert gas) and oxygen are mixed. When using a magnetron sputtering method, specifically, it may be carried out under the following film formation conditions. Sputtering gas: Mixed gas of Ar gas and N 2 and (O in the mixed gas 2 volume ratio of (N 2 / (Ar + N 2 )) = 15 vol% or more) Gas pressure 5.0×10 -2 ~1.0 Pa, preferably 1.0×10 -1 ~8.0×10 -1 Pa, more preferably 2.0×10 -1 ~4.0×10 -1 Pa Input power density per target area: 1.0 W / cm 2 ~15.0 W / cm 2 , preferably 3.0 W / cm 2 ~12.0 W / cm 2 , more preferably 4.0 W / cm 2 ~10.0 W / cm 2 Film formation rate: 0.010 nm / sec to 1.0 nm / sec, preferably 0.015 nm / sec to 0.50 nm / sec, more preferably 0.020 nm / sec to 0.30 nm / sec Distance between target and substrate: 50 mm to 500 mm, preferably 100 mm to 400 mm, more preferably 150 mm to 300 mm

[0082] When using an inert gas other than Ar, the concentration of the inert gas is set to the same concentration range as the above-mentioned Ar gas concentration. When using a plurality of types of inert gases, the total concentration of the inert gases is set to the same concentration range as the above-mentioned Ar gas concentration.

[0083] The EUV mask blanks 1a and 1b of the present invention may have functional films known in the field of EUV mask blanks, in addition to the multilayer reflective film 12, the protective film 13, the phase shift film 14, and the etching mask film 15. Specific examples of such functional films include, for example, a high-dielectric coating applied to the back surface side of the substrate in order to promote electrostatic chucking of the substrate, as described in Japanese Patent Application Laid-Open No. 2003-501823. Here, the back surface of the substrate refers to the surface of the substrate 11 in FIG. 1 that is opposite to the side on which the multilayer reflective film 12 is formed. The high-dielectric coating applied to the back surface of the substrate for such a purpose selects the electrical conductivity and thickness of the constituent materials so that the sheet resistance is 100 Ω / sq or less. As the constituent materials of the high-dielectric coating, those described in known documents can be widely selected. For example, a high-dielectric coating described in Japanese Patent Application Laid-Open No. 2003-501823, specifically, a coating made of Si, TiN, Mo, Cr, or TaSi can be applied. The thickness of the high-dielectric coating can be, for example, 10 to 1000 nm. The high-dielectric coating can be formed using known film-forming methods, for example, sputtering methods such as magnetron sputtering method and ion beam sputtering method, CVD method, vacuum evaporation method, and electroplating method.

[0084] The method for manufacturing an EUV mask blank of the present invention includes the following steps a) to c). a) A step of forming a multilayer reflective film that reflects EUV light on a substrate b) A step of forming a phase shift film on the multilayer reflective film formed in step a) c) A step of forming an etching mask film on the phase shift film formed in step c) According to the method for manufacturing an EUV mask blank of the present invention, the EUV mask blank 1b shown in FIG. 2 is obtained.

[0085] FIG. 3 is a schematic cross-sectional view showing one embodiment of the EUV mask of the present invention. The EUV mask 2 shown in FIG. 3 has a pattern (phase shift film pattern) 140 formed on the phase shift film 14 of the EUV mask blank 1a shown in FIG. 1. That is, a multilayer reflective film 12 that reflects EUV light, a protective film 13 of the multilayer reflective film 12, and a phase shift film 14 that shifts the phase of EUV light are formed in this order, and a pattern (phase shift film pattern) 140 is formed on the phase shift film 14. Among the components of the EUV mask 2, the substrate 11, the multilayer reflective film 12, the protective film 13, and the phase shift film 14 are the same as those of the EUV mask blank 1a described above.

[0086] In the method for manufacturing an EUV mask of the present invention, the phase shift film 14 of the EUV mask blank 1b manufactured by the method for manufacturing an EUV mask blank of the present invention is patterned to form a pattern (phase shift film pattern) 140. A procedure for forming a pattern on the phase shift film 14 of the EUV mask blank 1b will be described with reference to the drawings. As shown in FIG. 4, a resist film 30 is formed on the etching mask film 15 of the EUV mask blank 1b. Next, using an electron beam lithography machine, as shown in FIG. 5, a resist pattern 300 is formed on the resist film 30. Next, using the resist film 30 on which the resist pattern 300 is formed as a mask, as shown in FIG. 6, an etching mask film pattern 150 is formed on the etching mask film 15. For pattern formation of the etching mask film 15 made of an Nb-based material, dry etching using a chlorine-based gas may be performed as the etching gas. Next, using the etching mask film 15 on which the etching mask film pattern 150 is formed as a mask, as shown in FIG. 7, a phase shift film pattern 140 is formed on the phase shift film 14. For pattern formation of the phase shift film 14 containing Ru, O 2 or O 2Dry etching may be performed using a mixed gas of a noble gas and a halogen-based gas (chlorine-based gas, fluorine-based gas) as an etching gas. Next, by removing the resist film 30 and the etching mask film 15 with a cleaning liquid using an acid or a base, the EUV mask 2 with the phase shift film pattern 140 exposed is obtained. Note that most of the resist pattern 300 and the resist film 30 are removed in the process of forming the phase shift film pattern 140, but cleaning with a cleaning liquid using an acid or a base is performed for the purpose of removing the remaining resist pattern 300, resist film 30, and etching mask film 15.

Example

[0087] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples. Among Examples 1 to 22, Examples 1 to 15 are examples, and Examples 16 to 22 are comparative examples.

[0088] Example 1 In Example 1, an EUV mask blank 1a shown in FIG. 1 is produced. As the substrate 11 for film formation, a SiO 2 -TiO 2 -based glass substrate (outer shape: 6 inches (152 mm) square, thickness: 6.3 mm) is used. The thermal expansion coefficient of this glass substrate at 20 °C is 0.02 × 10 -7 / °C, Young's modulus is 67 GPa, Poisson's ratio is 0.17, and specific stiffness is 3.07 × 10 7 m 2 / s 2 . This glass substrate is polished to form a smooth surface with a surface roughness (rms) of 0.15 nm or less and flatness of 100 nm or less.

[0089] On the back side of the substrate 11, a high-dielectric coating with a sheet resistance of 100 Ω / □ is applied by forming a Cr film with a thickness of 100 nm using the magnetron sputtering method. A substrate 11 (outer shape: 6 inches (152 mm) square, thickness: 6.3 mm) is fixed to a normal electrostatic chuck having a flat plate shape via a formed Cr film, and an Si film and a Mo film are alternately formed on the surface of the substrate 11 using an ion beam sputtering method 40 times in repetition, thereby forming an Si / Mo multilayer reflective film 12 having a total film thickness of 272 nm ((4.5 nm + 2.3 nm) × 40). Furthermore, a protective film 13 is formed by forming a RuZr film (film thickness: 2.5 nm) on the Si / Mo multilayer reflective film 12 using a DC sputtering method.

[0090] The film formation conditions for the Si film, the Mo film, and the Ru film are as follows. Film Formation Conditions of Si Film Target: Si target (boron-doped) Sputtering gas: Ar gas (gas pressure: 2.0×10 -2 Pa) Voltage: 700 V Film formation rate: 0.077 nm / sec Film thickness: 4.5 nm Film Formation Conditions of Mo Film Target: Mo target Sputtering gas: Ar gas (gas pressure: 2.0×10 -2 Pa) Voltage: 700 V Film formation rate: 0.064 nm / sec Film thickness: 2.3 nm Film Formation Conditions of RuZr Film Target: Ru target Zr target Sputtering gas: Ar gas (gas pressure: 2.0×10 -2 Pa) Ru input power: 500 W Zr input power: 150 W Film formation rate: 0.073 nm / sec Film thickness: 2.5 nm

[0091] Next, on the protective film, a layer 1 of a phase shift film 14 containing Ru and O (RuO xThe film) is formed using a reactive sputtering method. The phase shift film 14 of this embodiment is composed of only layer 1. The film formation conditions for layer 1 of the phase shift film 14 are as follows. RuO x Film Formation Conditions of Film Target: Ru target Sputtering gas: Mixed gas of Ar gas and O 2 in the mixed gas (volume ratio of O 2 gas in the mixed gas (O 2 / (Ar + O 2 )) = 0.030, gas pressure: 2.0×10 -1 Pa) Input power density per target area: 7.4 W / cm 2 Film formation rate: 0.170 nm / sec Film thickness: 39 nm

[0092] For the EUV mask blank 1a obtained by the above procedure, the following evaluations (1) to (7) are carried out. For the following evaluations (1) to (7), the same evaluation results can also be obtained for the RuO x film formed on a silicon wafer.

[0093] (1) Film composition RuO x The composition of the film is measured using an X-ray Photoelectron Spectroscopy (manufactured by ULVAC-PHI, Inc.). The composition ratio (at%) of the RuO x film is Ru:O = 91:9.

[0094] (2) Calculation of phase difference and relative reflectance in the EUV wavelength region The phase difference between the reflected EUV light from the multilayer reflective film 12 and the reflected EUV light from the phase shift film 14, and the relative reflectance between the EUV light reflectance on the surface of the phase shift film 14 and the EUV light reflectance on the surface of the multilayer reflective film 12 are obtained by optical simulation. The optical constants of the multilayer reflective film 12 required for the simulation use the values in the database of the Center for X-Ray Optics, Lawrence Berkeley National Laboratory. The optical constants of the phase shift film 14 use those evaluated by measuring the "angle dependence" of the reflectance in the 13.5 nm region and the values in the database of the Center for X-Ray Optics, Lawrence Berkeley National Laboratory. Specifically, the EUV reflectance, the incident angle of EUV light, and the optical constants are expressed by the following equations. R = |(sinθ - ((n + ik) 2 - cos 2 θ) 1 / 2 ) / (sinθ + ((n + ik) 2 - cos 2 θ) 1 / 2 )| Here, θ is the incident angle of EUV light, R is the EUV reflectance at the incident angle θ, n is the refractive index of the phase shift film 14, and k is the attenuation coefficient of the phase shift film 14. By fitting the measured reflectance values at each EUV incident angle using the above equation, the EUV optical constants (refractive index (n), attenuation coefficient (k)) can be estimated. The refractive index (n) of the phase shift film 14 is 0.900, and the attenuation coefficient (k) is 0.017. The phase difference in the EUV wavelength region is 216 degrees, and the relative reflectance is 31.9%.

[0095] (3) Crystal peaks from the phase shift film For the phase shift film (RuO x film), measurement by the out-of-plane XRD method is performed. For the diffraction peak from the phase shift film observed at 2θ: 20° to 50° with the highest intensity, the full width at half maximum FWHM is obtained. The full width at half maximum FWHM is 1.0°, and the crystal structure of the phase shift film (RuO x film) is amorphous.

[0096] (4) Etching rate Place a sample with a phase shift film (RuO x film) formed on the sample stage of an ICP (inductively coupled) plasma etching apparatus, and perform ICP plasma etching under the conditions shown below to obtain the etching rate. ICP antenna bias: 200 W Substrate bias: 40 W Etching time: 30 sec Trigger pressure: 3.0×10 0 Pa Etching pressure: 3.0×10 -1 Pa Etching gas: O 2 and Cl 2 mixed gas Gas flow rate (Cl 2 / O 2 ): 10 / 10 sccm The etching rate is 25 nm / min.

[0097] Example 2 Example 2 is carried out in the same procedure as Example 1, except that the film formation conditions of layer 1 of the phase shift film 14 (RuO x film) are as follows. RuO x Film Formation Conditions of Film Target: Ru target Sputtering gas: Mixed gas of Ar gas and O 2 (Volume ratio of O gas in the mixed gas (O 2 / (Ar + O 2 )) = 0.04, gas pressure: 2.0×10 2 Pa) -1 Pa) Input power density per target area: 7.4 W / cm 2 Film formation rate: 0.22 nm / sec Film thickness: 45 nm RuOx The composition ratio (at%) of the film is Ru:O = 76:24. RuO x The refractive index (n) of the film is 0.912 and the extinction coefficient (k) is 0.019. The phase difference in the EUV wavelength region is 216 degrees and the relative reflectance is 23.5%. Phase shift film (RuO x film) The full width at half maximum FWHM of the crystal peak is 2.6°, and the crystal structure of the phase shift film (RuO x film) is amorphous. Phase shift film (RuO x film) The etching rate is 36 nm / min.

[0098] Example 3 Example 3 is carried out in the same procedure as Example 1 except that the film formation conditions of layer 1 (RuO x film) of the phase shift film 14 are set as the following conditions. RuO x Film Formation Conditions of Film Target: Ru target Sputtering gas: Mixed gas of Ar gas and O 2 (Volume ratio of O gas in the mixed gas (O 2 / (Ar + O 2 )) = 0.05, gas pressure: 2.0×10 2 Pa) -1 Input power density per target area: 7.4 W / cm 2 Film formation rate: 0.22 nm / sec Film thickness: 45 nm RuO x The composition ratio (at%) of the film is Ru:O = 67:33. RuO x The refractive index (n) of the film is 0.919 and the extinction coefficient (k) is 0.020. The phase difference in the EUV wavelength region is 216 degrees and the relative reflectance is 15.2%. Phase shift film (RuO x film) The full width at half maximum FWHM of the crystal peak is 3.2°, and the phase shift film (RuO​x The crystal structure of the film is amorphous. The phase shift film (RuO x The etching rate of the film is 41 nm / min.

[0099] Example 4 Example 4 is carried out in the same procedure as Example 1 except that a layer 1 (RuN film) of the phase shift film 14 containing Ru and N is formed on the protective film by using a reactive sputtering method. The film formation conditions of the phase shift film 14 are as follows. Film Formation Conditions of RuN Film Target: Ru target Sputtering gas: Mixed gas of Ar gas and N 2 in the mixed gas, the volume ratio of N 2 gas (N 2 / (Ar + N 2 )) = 0.5, gas pressure: 2.0×10 -1 Pa) Input power density per target area: 1.7 W / cm 2 Film formation rate: 0.017 nm / sec Film thickness: 39 nm The composition ratio (at%) of the RuN film is Ru:N = 98:2. The refractive index (n) of the RuN film is 0.890, and the extinction coefficient (k) is 0.016. The phase difference in the EUV wavelength region is 216 degrees, and the relative reflectance is 35.4%. The full width at half maximum FWHM of the crystal peak derived from the phase shift film (RuN film) is 1.2°, and the crystal structure of the phase shift film (RuN film) is amorphous. is. The etching rate of the phase shift film (RuN film) is 23 nm / min.

[0100] Example 5 Example 5 is carried out in the same procedure as Example 1 except that a layer 1 (RuON film) of the phase shift film 14 containing Ru, O and N is formed on the protective film by using a reactive sputtering method. The film formation conditions of layer 1 of the phase shift film 14 are as follows. Film Formation Conditions of RuON Film Target: Ru target Sputtering gas: Ar gas and O 2 and N 2 mixed gas (volume ratio of O gas in the mixed gas (O 2 gas) (O 2 / (Ar + O 2 + N 2 )) = 0.013, volume ratio of N gas in the mixed gas (N 2 gas) (N 2 / (Ar + O 2 + N 2 )) = 0.2, gas pressure: 2.0×10 -1 Pa) Input power density per target area: 7.4 W / cm 2 Film deposition rate: 0.13 nm / sec Film thickness: 39 nm The composition ratio (at%) of the RuON film is Ru:O:N = 93:2:5 (Ru:O + N = 93:7). The refractive index (n) of the RuON film is 0.901, and the extinction coefficient (k) is 0.017. The phase difference in the EUV wavelength region is 216 degrees, and the relative reflectance is 31.8%. The full width at half maximum FWHM of the crystal peak derived from the phase shift film (RuON film) is 1.9°, and the crystal structure of the phase shift film (RuON film) is amorphous. The etching rate of the phase shift film (RuON film) is 26 nm / min.

[0101] Example 6 Example 6 is carried out in the same procedure as Example 5, except that the film formation conditions of layer 1 (RuON film) of the phase shift film 14 are set as the following conditions. Film Formation Conditions of RuON Film Target: Ru target Sputtering gas: Ar gas and O 2 and N 2 mixed gas (volume ratio of O gas in the mixed gas (O 2 gas) (O 2 / (Ar + O 2 + N 2)) = 0.026, N in the mixed gas 2 Volume ratio of gas (N 2 / (Ar + O 2 + N 2 )) = 0.2, gas pressure: 2.0×10 -1 Pa) Input power density per target area: 7.4 W / cm 2 Film deposition rate: 0.17 nm / sec Film thickness: 39 nm The composition ratio (at%) of the RuON film is Ru:O:N = 76:14:10 (Ru:O + N = 76:24). The refractive index (n) of the RuON film is 0.912 and the extinction coefficient (k) is 0.019. The phase difference in the EUV wavelength region is 216 degrees and the relative reflectance is 23.5%. Since no crystal peak derived from the phase shift film (RuON film) was observed, the full width at half maximum FWHM is 180° and the crystal structure of the phase shift film (RuON film) is amorphous. The etching rate of the phase shift film (RuON film) is 32 nm / min.

[0102] Example 7 Example 7 is carried out in the same procedure as Example 5, except that the film formation conditions of layer 1 (RuON film) of the phase shift film 14 are the following conditions. Film Formation Conditions of RuON Film Target: Ru target Sputtering gas: Ar gas and O 2 and N 2 mixed gas (O in the mixed gas 2 Volume ratio of gas (O 2 / (Ar + O 2 + N 2 )) = 0.051, N in the mixed gas 2 Volume ratio of gas (N 2 / (Ar + O 2 + N 2 )) = 0.19, gas pressure: 2.0×10 -1 Pa) Input power density per target area: 7.4 W / cm 2 Film formation rate: 0.21 nm / sec Film thickness: 46 nm The composition ratio (at%) of the RuON film is Ru:O:N = 62:29:9 (Ru:O + N = 62:38). The refractive index (n) of the RuON film is 0.919, and the extinction coefficient (k) is 0.020. The phase difference in the EUV wavelength region is 1.2 degrees, and the relative reflectance is 11.8%. Since no crystal peak derived from the phase shift film (RuON film) was observed, the full width at half maximum FWHM is 180°, and the crystal structure of the phase shift film (RuON film) is amorphous. The etching rate of the phase shift film (RuON film) is 35 nm / min.

[0103] Example 8 Example 8 is carried out in the same procedure as Example 5, except that the film formation conditions of layer 1 (RuON film) of the phase shift film 14 are as follows. RuO x Film Formation Conditions of N Film Target: Ru target Sputtering gas: Ar gas and O 2 and N 2 mixed gas (volume ratio of O gas in the mixed gas (O 2 / (Ar + O 2 + N 2 )) = 0.17, volume ratio of N gas in the mixed gas (N 2 / (Ar + O 2 + N 2 )) = 0.17, gas pressure: 2.0×10 2 Pa) 2 -1 Input power density per target area: 7.4 W / cm 2 Film formation rate: 0.20 nm / sec Film thickness: 52 nm The composition ratio (at%) of the RuON film is Ru:O:N = 38:51:11 (Ru:O + N = 38:62). RuO​​x The refractive index (n) of the N film is 0.922, and the extinction coefficient (k) is 0.021. The phase difference in the EUV wavelength region is 216 degrees, and the relative reflectance is 15.7%. Since no crystal peak derived from the phase shift film (RuON film) was observed, the full width at half maximum FWHM is 180°, and the crystal structure of the phase shift film (RuON film) is amorphous. The etching rate of the phase shift film (RuON film) is 37 nm / min.

[0104] Example 9 Example 9 is carried out in the same procedure as Example 1, except that a layer 1 (RuCrN film) of the phase shift film 14 containing Ru, Cr, and N is formed on the protective film using the reactive sputtering method. The film formation conditions for layer 1 of the phase shift film 14 are as follows. Film Formation Conditions of RuCrN Film Target: Ru target Cr target Sputtering gas: Mixed gas of Ar gas and N 2 gas (volume ratio of N gas in the mixed gas (N 2 / (Ar + O 2 + N 2 )) = 1, gas pressure: 2.5×10 2 Pa) -1 Input power density per target area: Ru target 4.9 W / cm 2 Cr target 9.9 W / cm 2 Film formation rate: 0.10 nm / sec Film thickness: 52 nm The composition ratio (at%) of the RuCrN film is Ru:Cr:N = 37:33:30 (Ru + Cr:N = 70:30, Cr / Ru = 0.9). The refractive index (n) of the RuCrN film is 0.921, and the extinction coefficient (k) is 0.023. The phase difference in the EUV wavelength region is 216 degrees, and the relative reflectance is 8.7%. ​The full width at half maximum (FWHM) of the crystal peak derived from the phase shift film (RuCrN film) is 2.3°, and the crystal structure of the phase shift film (RuCrN film) is amorphous. The etching rate of the phase shift film (RuCrN film) has not been measured.

[0105] Example 10 Example 10 is carried out in the same procedure as Example 1 except that a layer 1 (RuCrON film) of the phase shift film 14 containing Ru, Cr, O, and N is formed on the protective film using the reactive sputtering method. The film formation conditions for layer 1 of the phase shift film 14 are as follows. Film Formation Conditions of RuCrON Film Target: Ru target Cr target Ar gas and N 2 and O 2 mixed gas (volume ratio of N gas in the mixed gas (N 2 / (Ar + O 2 + N 2 )) = 0.2, volume ratio of O gas in the mixed gas (O 2 / (Ar + O 2 + N 2 )) = 0.033, gas pressure: 2.0×10 2 Pa) 2 )) = 0.033, gas pressure: 2.0×10 -1 Pa) Input power density per target area: Ru target 4.9 W / cm 2 Cr target 9.9 W / cm 2 Film formation rate: 0.31 nm / sec Film thickness: 52 nm The composition ratio (at%) of the RuCrON film is Ru:Cr:O:N = 14:35:41:10 (Ru + Cr:O + N = 49:51, Cr / Ru = 2.5). The refractive index (n) of the RuCrON film is 0.923, and the extinction coefficient (k) is 0.031. The phase difference in the EUV wavelength region is 216 degrees, and the relative reflectance is 12.6%. Since no crystal peak derived from the phase shift film (RuCrON film) was observed, the full width at half maximum FWHM was 180°, and the crystal structure of the phase shift film (RuCrON film) was amorphous. The etching rate of the phase shift film (RuCrON film) has not been measured.

[0106] Example 11 Example 11 is carried out in the same procedure as Example 1 except that a layer 1 (RuReON film) of the phase shift film 14 containing Ru, Re, O, and N is formed on the protective film by using a reactive sputtering method. The film formation conditions for layer 1 of the phase shift film 14 are as follows. Film Formation Conditions of RuReON Film Target: Ru target Re target Ar gas and N 2 and O 2 mixed gas (volume ratio of N gas in the mixed gas (N 2 / (Ar + O 2 + N 2 )) = 0.2, volume ratio of O gas in the mixed gas (O 2 / (Ar + O 2 + N 2 )) = 0.1, gas pressure: 3.0×10 2 Pa) 2 -1 Input power density per target area: Ru target 2.5 W / cm 2 Re target 7.4 W / cm 2 Film formation rate: 0.16 nm / sec Film thickness: 52 nm The composition ratio (at%) of the RuReON film is Ru:Re:O:N = 16:71:2:11 (Ru + Cr:O + N = 87:13, Cr / Ru = 4.4). The refractive index (n) of the RuReON film is 0.928, and the extinction coefficient (k) is 0.029. The phase difference in the EUV wavelength region is 216 degrees, and the relative reflectance is 6.1%. ​​The full width at half maximum (FWHM) of the crystal peak derived from the phase shift film (RuReON film) is 4°, and the crystal structure of the phase shift film (RuReON film) is amorphous. The etching rate of the phase shift film (RuReON film) has not been measured.

[0107] Example 12 Example 12 is carried out in the same procedure as Example 11, except that the film formation conditions of layer 1 (RuReON film) of the phase shift film 14 are set as the following conditions. Film Formation Conditions of RuReON Film Target: Ru target Re target Ar gas and N 2 and O 2 mixed gas (volume ratio of N gas in the mixed gas (N 2 / (Ar + O 2 + N 2 )) = 0.2, volume ratio of O gas in the mixed gas (O 2 / (Ar + O 2 + N 2 )) = 0.016, gas pressure: 3.0×10 2 Pa) 2 -1 -1 Pa) Input power density per target area: Ru target 7.4 W / cm 2 Re target 7.4 W / cm 2 Film formation rate: 0.30 nm / sec Film thickness: 52 nm The composition ratio (at%) of the RuReON film is Ru:Re:O:N = 41:48:2:9 (Ru + Re:O + N = 89:11, Re / Ru = 1.2). The refractive index (n) of the RuReON film is 0.914, and the extinction coefficient (k) is 0.026. The phase difference in the EUV wavelength region is 216 degrees, and the relative reflectance is 14.2%. The full width at half maximum (FWHM) of the crystal peak derived from the phase shift film (RuReON film) is 1.3°, and the crystal structure of the phase shift film (RuReON film) is amorphous. The etching rate of the phase shift film (RuReON film) has not been measured.

[0108] Example 13 Example 13 is carried out in the same procedure as Example 11, except that the film formation conditions of layer 1 (RuReON film) of the phase shift film 14 are set as the following conditions. Film Formation Conditions of RuReON Film Target: Ru target Re target Ar gas and N 2 and O 2 mixed gas (volume ratio of N gas in the mixed gas (N 2 / (Ar + O 2 + N 2 )) = 0.2, volume ratio of O gas in the mixed gas (O 2 / (Ar + O 2 + N 2 )) = 0.016, gas pressure: 3.0×10 2 Pa) 2 )) = 0.016, gas pressure: 3.0×10 -1 Pa) Input power density per target area: Ru target 7.4 W / cm 2 Re target 2.5 W / cm 2 Film formation rate: 0.19 nm / sec Film thickness: 44 nm The composition ratio (at%) of the RuReON film is Ru:Re:O:N = 71:18:3:11 (Ru + Re:O + N = 89:11, Re / Ru = 0.3). The refractive index (n) of the RuReON film is 0.904, and the extinction coefficient (k) is 0.020. The phase difference in the EUV wavelength region is 216 degrees, and the relative reflectance is 21.0%. The full width at half maximum FWHM of the crystal peak derived from the phase shift film (RuReON film) is 3°, and the crystal structure of the phase shift film (RuReON film) is amorphous. The etching rate of the phase shift film (RuReON film) has not been measured.

[0109] Example 14 Example 14 is carried out in the same procedure as Example 9, except that the film formation conditions of layer 1 (RuCrN film) of the phase shift film 14 are set as follows. Film Formation Conditions of RuCrN Film Target: Ru target Cr target Sputtering gas: Mixed gas of Ar gas and N 2 in the mixed gas, the volume ratio of N 2 gas (N 2 / (Ar + O 2 + N 2 )) = 0.17, gas pressure: 2.0×10 -1 Pa) Input power density per target area: 3.7 W / cm for Ru target 2 4.9 W / cm for Cr target 2 Film formation rate: 0.07 nm / sec Film thickness: 40 nm The composition ratio (at%) of the RuCrN film is Ru:Cr:N = 42:44:14 (Ru + Cr:N = 86:14, Cr / Ru = 1). The refractive index (n) of the RuCrN film is 0.920, and the extinction coefficient (k) is 0.024. The phase difference in the EUV wavelength region is 216 degrees, and the relative reflectance is 10.2%. The full width at half maximum FWHM of the crystal peak derived from the phase shift film (RuCrN film) is 2.8°, and the crystal structure of the phase shift film (RuCrN film) is amorphous. The etching rate of the phase shift film (RuCrN film) has not been measured.

[0110] Example 15 Example 10 is carried out in the same procedure as Example 1, except that layer 1 (RuCrO film) of the phase shift film 14 containing Ru, Cr, and O is formed on the protective film using the reactive sputtering method. The film formation conditions of layer 1 of the phase shift film 14 are as follows. Film Formation Conditions of RuCrO Film Target: Ru target Cr target Ar gas and O 2 mixed gas (O in the mixed gas 2 volume ratio of gas (O 2 / (Ar + O 2 )) = 0.2, gas pressure: 2.0×10 -1 Pa) Input power density per target area: Ru target 7.4 W / cm 2 Cr target 5.9 W / cm 2 Film formation rate: 0.49 nm / sec Film thickness: 40 nm The composition ratio (at%) of the RuCrO film is Ru:Cr:O = 20:30:50 (Ru + Cr:O = 50:50, Cr / Ru = 0.6). It is. The refractive index (n) of the RuCrO film is 0.929, and the extinction coefficient (k) is 0.027. The phase difference in the EUV wavelength region is 216 degrees, and the relative reflectance is 7.3%. Since no crystal peak derived from the phase shift film (RuCrO film) was observed, the full width at half maximum FWHM is 180°, and the crystal structure of the phase shift film (RuCrO film) is amorphous. The etching rate of the phase shift film (RuCrO film) has not been measured.

[0111] Example 16 Example 16 is carried out in the same procedure as Example 1, except that a layer 1 (RuON film) of the phase shift film 14 containing Ru, O, and N is formed on the protective film by a reactive sputtering method, and a layer 2 (TaON film) of the phase shift film 14 containing Ta, O, and N is formed by a reactive sputtering method. The film formation conditions for layer 1 and layer 2 of the phase shift film 14 are as follows. Film Formation Conditions of RuON Film Target: Ru target Sputtering gas: Ar gas and O 2 and N 2 mixed gas (O in the mixed gas 2 volume ratio of gas (O2 / (Ar + O 2 + N 2 )) = 0.17, the volume ratio of N gas in the mixed gas (N 2 gas in the mixed gas (N 2 / (Ar + O 2 + N 2 )) = 0.17, gas pressure: 2.0×10 -1 Pa) Input power density per target area: 7.4 W / cm 2 Film deposition rate: 0.20 nm / sec Film thickness: 48 nm Film Formation Conditions of TaON Film Target: Ta target Sputtering gas: Ar gas and O 2 and N 2 mixed gas (the volume ratio of O gas in the mixed gas (O 2 gas in the mixed gas (O 2 / (Ar + O 2 + N 2 )) = 0.4, the volume ratio of N gas in the mixed gas (N 2 gas in the mixed gas (N 2 / (Ar + O 2 + N 2 )) = 0.1, gas pressure: 2.0×10 -1 Pa) Input power density per target area: 7.4 W / cm 2 Film deposition rate: 0.10 nm / sec Film thickness: 4 nm The composition ratio (at%) of the RuON film is Ru:O:N = 38:51:11 (Ru:O + N = 38:62). The refractive index (n) of the RuON film is 0.922 and the extinction coefficient (k) is 0.021. The refractive index (n) of the TaON film is 0.955 and the extinction coefficient (k) is 0.025. The phase difference in the EUV wavelength region is 216 degrees and the relative reflectance is 12.9%. Since no crystal peaks were observed from the phase shift film (layer 1 (RuON film) and layer 2 (TaON film)), the full width at half maximum (FWHM) was 180°, and the crystal structure of the phase shift film 14 including layer 1 (RuON film) and layer 2 (TaON film) was amorphous. The etching rates of layer 1 (RuON film) and layer 2 (TaON film) of the phase shift film 14 have not been measured.

[0112] Example 17 Example 17 is carried out in the same procedure as Example 1, except that layer 2 (CrN film) of the phase shift film 14 containing Cr and N is formed on the protective film using the reactive sputtering method, and layer 1 (RuON film) of the phase shift film 14 containing Ru, O and N is formed using the reactive sputtering method. The film formation conditions for layer 2 and layer 1 of the phase shift film 14 are as follows. Film Formation Conditions of CrN Film Target: Cr target Sputtering gas: Mixed gas of Ar gas and N 2 (Volume ratio of N gas in the mixed gas (N 2 / (Ar + N 2 )) = 0.2, gas pressure: 2.0×10 2 Pa) -1 Input power density per target area: 9.9 W / cm 2 Film formation rate: 0.09 nm / sec Film thickness: 4 nm Film Formation Conditions of RuON Film Target: Ru target Sputtering gas: Mixed gas of Ar gas, O 2 and N 2 (Volume ratio of O gas in the mixed gas (O 2 / (Ar + O 2 + N 2 )) = 0.17, volume ratio of N gas in the mixed gas (N 2 / (Ar + O 2 + N 2 )) = 0.17, gas pressure: 2.0×10 2 + N 2 )) = 0.17, gas pressure: 2.0×10 -1 Pa) Input power density per target area: 7.4 W / cm 2 Film formation rate: 0.20 nm / sec Film thickness: 48 nm The composition ratio (at%) of the RuON film is Ru:O:N = 38:51:11 (Ru:O + N = 38:62). The refractive index (n) of the RuON film is 0.922, and the extinction coefficient (k) is 0.021. The refractive index (n) of the CrN film is 0.928, and the extinction coefficient (k) is 0.039. The phase difference in the EUV wavelength region is 216 degrees, and the relative reflectance is 13.6%. The full width at half maximum FWHM of the crystal peak derived from the phase shift film (layer 2 (CrN film), layer 1 (RuON film)) is 3.6°, and the crystal structure of the phase shift film 14 including layer 2 (CrN film) and layer 1 (RuON film) is amorphous. The etching rates of layer 2 (CrN film) and layer 1 (RuON film) of the phase shift film 14 have not been measured.

[0113] Example 18 Example 18 is carried out in the same procedure as Example 1 except that a phase shift film 14 (Ru film) containing Ru is formed on the protective film using the DC sputtering method. The film formation conditions of the phase shift film 14 are as follows. Film Formation Conditions of Ru Film Target: Ru target Sputtering gas: Ar gas (gas pressure: 2.0×10 -1 Pa) Input power density per target area: 7.4 W / cm 2 Film formation rate: 0.14 nm / sec Film thickness: 40 nm The full width at half maximum FWHM of the crystal peak derived from the phase shift film (Ru film) is 0.42°, and the crystal structure of the phase shift film (Ru film) is crystalline. The phase difference and relative reflectance in the EUV wavelength region have not been measured. The etching rate of the phase shift film (Ru film) has not been measured.

[0114] Example 19 Example 19 is carried out in the same procedure as Example 1 except that a phase shift film 14 (RuO 2 film) containing Ru and O is formed on the protective film by using a reactive sputtering method. The film formation conditions of the phase shift film 14 are as follows. RuO 2 Film Formation Conditions of Film Target: Ru target Mixed gas of Ar gas and O 2 (Volume ratio of O gas in the mixed gas (O 2 / (Ar + O 2 )) = 0.13, gas pressure: 2.0×10 2 Pa) -1 Pa) Input power density per target area: 7.4 W / cm 2 Film formation rate: 0.26 nm / sec Film thickness: 40 nm RuO 2 The composition ratio (at%) of the RuO film is Ru:O = 38:62. The full width at half maximum FWHM of the crystal peak derived from the phase shift film (RuO 2 film) is 0.82°, and the crystal structure of the phase shift film (RuO 2 film) is crystalline. The phase difference and relative reflectance in the EUV wavelength region have not been measured. The etching rate of the phase shift film (RuO 2 film) has not been measured.

[0115] Example 20 Example 20 is carried out in the same procedure as Example 1 except that a phase shift film 14 (RuCr film) containing Ru and Cr is formed on the protective film by using a binary sputtering method. The film formation conditions of the phase shift film 14 are as follows. Film Formation Conditions of RuCr Film Target: Ru target Cr target Ar gas (gas pressure: 2.0×10-1 Pa) Input power density per target area: Ru target 7.4 W / cm 2 Cr target 4.9 W / cm 2 Film deposition rate: 0.21 nm / sec Film thickness: 40 nm The composition ratio (at%) of the RuCr film is Ru:Cr = 65:35. The full width at half maximum FWHM of the crystal peak derived from the phase shift film (RuCr film) is 0.34°, and the crystal structure of the phase shift film (RuCr film) is crystalline. The phase difference and relative reflectance in the EUV wavelength region have not been measured. The etching rate of the phase shift film (RuCr film) has not been measured.

[0116] Example 21 Example 21 is carried out in the same procedure as Example 1 except that a phase shift film 14 (RuRe film) containing Ru and Re is formed on the protective film by a binary sputtering method. The film formation conditions of the phase shift film 14 are as follows. Film Formation Conditions of RuRe Film Target: Ru target Re target Ar gas (gas pressure: 2.0×10 -1 Pa) Input power density per target area: Ru target 7.4 W / cm 2 Re target 7.4 W / cm 2 Film deposition rate: 0.25 nm / sec Film thickness: 40 nm The composition ratio (at%) of the RuRe film is Ru:Re = 50:50. The full width at half maximum FWHM of the crystal peak derived from the phase shift film (RuRe film) is 0.40°, and the crystal structure of the phase shift film (RuRe film) is crystalline. The phase difference and relative reflectance in the EUV wavelength region have not been measured. The etching rate of the phase shift film (RuRe film) has not been measured.

[0117] Example 22 Example 22 is carried out in the same procedure as Example 1 except that a phase shift film 14 (RuN film) containing Ru and N is formed on the protective film by using a reactive sputtering method. The film formation conditions of the phase shift film 14 are as follows. Film Formation Conditions of RuN Film Target: Ru target Sputtering gas: Mixed gas of Ar gas and N 2 (The volume ratio of N gas in the mixed gas (N 2 gas / (Ar + N 2 )) = 0.2, gas pressure: 2.0×10 2 Pa) -1 Input power density per target area: 7.4 W / cm 2 Film formation rate: 0.07 nm / sec Film thickness: 40 nm The composition ratio (at%) of the RuN film is Ru:N = 99:1. The full width at half maximum FWHM of the crystal peak derived from the phase shift film (RuN film) is 0.72°, and the crystal structure of the phase shift film (RuN film) is crystalline. The phase difference and relative reflectance in the EUV wavelength region have not been measured. The etching rate of the phase shift film (RuN film) has not been measured.

[0118] Example 23 Example 23 is carried out in the same procedure as Example 1 except that a phase shift film 14 (RuReN film) containing Ru, Re and N is formed on the protective film by using a reactive sputtering method. The film formation conditions of the phase shift film 14 are as follows. Film Formation Conditions of RuReN Film Target: Ru target Re target Sputtering gas: Mixed gas of Ar gas and N 2 (The N in the mixed gas 2 gas volume ratio (N2 / (Ar + N 2 )) = 0.04, gas pressure: 3.0×10 -1 Pa) Input power density per target area: Ru target 7.4 W / cm 2 Re target 7.4 W / cm 2 Film formation rate: 0.32 nm / sec Film thickness: 40 nm The composition ratio (at%) of the RuReN film is Ru:Re:N = 41:58:1 (Ru + Re:N = 99:1, Re / Ru = 0.7). The full width at half maximum FWHM of the crystal peak derived from the phase shift film (RuReN film) is 0.4°, and the crystal structure of the phase shift film (RuReN film) is crystalline. The phase difference and relative reflectance in the EUV wavelength region have not been measured. The etching rate of the phase shift film (RuReN film) has not been measured.

[0119] Example 24 Example 24 is carried out in the same procedure as Example 1 except that a phase shift film 14 (RuCrN film) containing Ru, Cr, and N is formed on the protective film using the reactive sputtering method. The film formation conditions of the phase shift film 14 are as follows. Film Formation Conditions of RuCrN Film Target: Ru target Cr target Sputtering gas: Ar gas and N 2 mixed gas (N in the mixed gas 2 volume ratio of gas (N 2 / (Ar + N 2 )) = 0.09, gas pressure: 2.0×10 -1 Pa) Input power density per target area: Ru target 7.4 W / cm 2 Cr target 7.4 W / cm 2 Film formation rate: 0.24 nm / sec Film thickness: 40 nm The composition ratio (at%) of the RuCrN film is Ru:Cr:N = 61:31:8. The full width at half maximum (FWHM) of the crystal peak derived from the phase shift film (RuCrN film) is 0.52°, and the crystal structure of the phase shift film (RuCrN film) is crystalline. The phase difference and relative reflectance in the EUV wavelength region have not been measured. The etching rate of the phase shift film (RuCrN film) has not been measured.

[0120] Reference Example In the reference example, a layer 1 (RuO x film, or RuO x N film) of the phase shift film 14 containing Ru and O, or Ru, O, and N is formed on a Si wafer using a reactive sputtering method. The film formation conditions for layer 1 of the phase shift film 14 are as follows. Note that the volume ratio of O 2 gas in the mixed gas is shown in the range because a plurality of samples are prepared under conditions where the volume ratio of O 2 gas in the mixed gas is different. RuO x Film Formation Conditions of Film Target: Ru target A mixed gas of Ar gas and O 2 (the volume ratio of O 2 gas in the mixed gas (O 2 / (Ar + O 2 )) = 0.03 to 0.17, gas pressure: 2.0 × 10 -1 Pa) Input power density per target area: 7.4 W / cm 2 Film formation rate: 0.13 to 0.30 nm / sec Film thickness: 40 nm RuO x Film Formation Conditions of N Film Target: Ru target A mixed gas of Ar gas and N 2 and O 2 (the volume ratio of N 2 gas in the mixed gas (N 2 / (Ar + O2 +N 2 )) = 0.2, O in the mixed gas 2 Volume ratio of gas (O 2 / (Ar + O 2 +N 2 )) = 0.026 - 0.17, gas pressure: 2.0×10 -1 Pa) Input power: 150 W Film deposition rate: 0.13 - 0.30 nm / sec Film thickness: 40 nm Phase shift film 14 (RuO x film, RuO x The surface roughness (RMS) of the surface of the N film) is measured using an Atomic Force Microscope. Figure 8 is a diagram showing the relationship between the full width at half maximum FWHM (°) in the reference example and the surface roughness RMS (nm) of the phase shift film. From Figure 8, it can be seen that in the case of both the RuO x film and the RuO x N film, when the full width at half maximum FWHM of the phase shift film 14 is 1.0° or more, the surface roughness (RMS) of the surface of the phase shift film 14 becomes 0.3 nm or less.

Explanation of symbols

[0121] 1a, 1b: EUV mask blank 2: EUV mask 11: Substrate 12: Multilayer reflective film 13: Protective film 14: Phase shift film 15: Etching mask film 30: Resist film 140: Phase shift film pattern 150: Etching mask film pattern 300: Resist pattern

Claims

1. A reflective mask blank for EUV lithography, in which a multilayer reflective film that reflects EUV light and a phase shift film that shifts the phase of EUV light are formed in this order on a substrate, wherein the phase shift film has a layer 1 containing ruthenium (Ru) and at least one selected from the group consisting of oxygen (O) and nitrogen (N), wherein the layer 1 contains Ru in the range of 40 to 99 at% and O in the range of 1 to 60 at%, wherein the layer 1 further contains at least one element (X) selected from the group consisting of chromium (Cr), tantalum (Ta), titanium (Ti), rhenium (Re), tungsten (W), bismuth (Bi), manganese (Mn), platinum (Pt), copper (Cu), iridium (Ir), and vanadium (V) in a composition ratio (at%) (Ru:X) of 20:1 to 1:5 between Ru and X, and contains the total of Ru and X (Ru + X) in the range of 50 to 99 at% and O in the range of 1 to 50 at%, characterized in that, in the out of plane XRD method, the full width at half maximum FWHM of the diffraction peak derived from the phase shift film observed at 2θ: 20° to 50° is 1.0° or more, a protective film of the multilayer reflective film is formed between the multilayer reflective film and the phase shift film, the protective film contains at least one element selected from the group consisting of Ru, palladium (Pd), Ir, rhodium (Rh), Pt, zirconium (Zr), niobium (Nb), Ta, and Ti, and is a reflective mask blank for EUV lithography.

2. A reflective mask blank for EUV lithography, in which a multilayer reflective film that reflects EUV light and a phase shift film that shifts the phase of EUV light are formed in this order on a substrate, wherein the phase shift film has a layer 1 containing ruthenium (Ru) and at least one selected from the group consisting of oxygen (O) and nitrogen (N), wherein the layer 1 contains Ru in the range of 30 to 98 at%, O in the range of 1 to 69 at%, and N in the range of 1 to 69 at%, wherein the layer 1 further contains at least one element (X) selected from the group consisting of Cr, Ta, Ti, Re, W, Bi, Mn, Pt, Cu, Ir, and V in a composition ratio (at%) (Ru:X) of 20:1 to 1:5 between Ru and X, and contains the total of Ru and X (Ru + X) in the range of 30 to 98 at%, O in the range of 1 to 69 at%, and N in the range of 1 to 69 at%, In the out-of-plane XRD method, among the diffraction peaks derived from the phase shift film observed at 2θ: 20° to 50°, the full width at half maximum (FWHM) of the peak with the highest intensity is 1.0° or more. A protective film of the multilayer reflective film is formed between the multilayer reflective film and the phase shift film. The reflective mask blank for EUV lithography, wherein the protective film contains at least one element selected from the group consisting of Ru, palladium (Pd), Ir, rhodium (Rh), Pt, zirconium (Zr), niobium (Nb), Ta, and Ti.

3. A reflective mask blank for EUV lithography, in which a multilayer reflective film that reflects EUV light and a phase shift film that shifts the phase of EUV light are formed in this order on a substrate. The phase shift film has a layer 1 containing ruthenium (Ru) and at least one selected from the group consisting of oxygen (O) and nitrogen (N). The layer 1 contains Ru in the range of 30 to 98 at% and N in the range of 2 to 70 at%. The layer 1 further contains at least one element (X) selected from the group consisting of Cr, Ti, Re, W, Bi, Mn, Pt, Cu, Ir, and V in a composition ratio (at%) (Ru:X) of 20:1 to 1:5 between Ru and X, and contains the total of Ru and X (Ru + X) in the range of 60 to 90 at% and N in the range of 10 to 40 at%. In the out-of-plane XRD method, among the diffraction peaks derived from the phase shift film observed at 2θ: 20° to 50°, the full width at half maximum (FWHM) of the peak with the highest intensity is 1.0° or more. A protective film of the multilayer reflective film is formed between the multilayer reflective film and the phase shift film. The reflective mask blank for EUV lithography, wherein the protective film contains at least one element selected from the group consisting of Ru, palladium (Pd), Ir, rhodium (Rh), Pt, zirconium (Zr), niobium (Nb), Ta, and Ti.

4. The reflective mask blank for EUV lithography according to any one of claims 1 to 3, wherein the layer 1 contains at least one element selected from the group consisting of Cr and Re as the element (X).

5. The reflective mask blank for EUV lithography according to any one of claims 1 to 4, wherein the composition ratio (at%) (Ru:X) between Ru and X in the layer 1 is in the range of 4:1 to 1:

4.

6. The reflective mask blank for EUV lithography according to any one of claims 1 to 5, wherein the phase shift film further has a layer 2 containing at least one element (X) selected from the group consisting of Cr, Ta, Ti, Re, W, Bi, Mn, Pt, Cu, Ir, and V.

7. The reflective mask blank for EUV lithography according to any one of claims 1 to 5, wherein the phase shift film further has a layer 2 containing at least one element (X) selected from the group consisting of Cr and Ta.

8. The reflective mask blank for EUV lithography according to claim 6 or 7, wherein the layer 2 further contains at least one element selected from the group consisting of O, N, B, and C.

9. The reflective mask blank for EUV lithography according to any one of claims 6 to 8, wherein the relative ratio of the thickness of the layer 1 to the thickness of the layer 2 ((thickness of layer 1):(thickness of layer 2)) is 1:1 to 30:

1.

10. The reflective mask blank for EUV lithography according to any one of claims 6 to 9, wherein the phase shift film has the layer 2 on the layer 1.

11. The reflective mask blank for EUV lithography according to any one of claims 1 to 10, wherein the film thickness of the phase shift film is 20 nm to 60 nm.

12. The reflective mask blank for EUV lithography according to any one of claims 1 to 11, wherein the thickness of the layer 1 is 10 nm or more.

13. The reflective mask blank for EUV lithography according to any one of claims 1 to 12, wherein the phase difference between the reflected light of EUV light from the multilayer reflective film and the reflected light of EUV light from the phase shift film is 150 degrees to 250 degrees, and the relative reflectance ((reflectance of EUV light on the surface of the phase shift film / reflectance of EUV light on the surface of the multilayer reflective film) × 100) between the reflectance of EUV light on the surface of the phase shift film and the reflectance of EUV light on the surface of the multilayer reflective film is 2% to 37%.

14. The reflective mask blank for EUV lithography according to any one of claims 1 to 13, wherein the protective film further contains at least one element selected from the group consisting of O, N, and B.

15. On the phase shift film, there is an etching mask film, and the etching mask film contains at least one element selected from the group consisting of Nb, Ti, molybdenum (Mo), Ta, and Si. The reflective mask blank for EUV lithography according to any one of claims 1 to 14.

16. The reflective mask blank for EUV lithography according to claim 15, wherein the etching mask film further contains at least one element selected from the group consisting of O, N, and B.

17. A reflective mask for EUV lithography, in which a pattern is formed on the phase shift film of the reflective mask blank for EUV lithography according to any one of claims 1 to 16.

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