Reflection type mask blank, reflection type mask, method for manufacturing reflection type mask blank, and method for manufacturing reflection type mask

Abstract

To provide a technique of reducing the surface roughness of a phase shift film or a conductive film while maintaining resistance of the phase shift film or the conductive film to SPM.SOLUTION: A reflection type mask blank has a substrate, a multilayer reflection film reflecting EUV light, a protective film protecting the multilayer reflection film, a phase shift film shifting the phase of EUV light in this order. The phase shift film contains a Cr compound containing chromium (Cr) and nitrogen (N). In the Cr compound, a difference between the binding energy (BE1) of Cr2p3 / 2 and the binding energy (BE2) of N1s (ΔBE:ΔBE=BE1-BE2) measured by XPS is 177.3 eV or less. In the Cr compound, the full width at half maximum of a peak of diffraction intensity in which diffraction angle 2θ is detected within the range of 35° to 52°, which is measured by In-Plane XRD using CuKα ray, is 2.1° or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] In recent years, with the miniaturization of semiconductor devices, EUV lithography (EUVL), an exposure technology using extreme ultraviolet (EUV) light, has been developed. EUV has a wavelength of approximately 13.5 nm. EUVL uses a reflective mask. A reflective mask has, in this order, a substrate such as a glass substrate, a multilayer reflective film that reflects EUV light, and an absorbing film that absorbs EUV light. The absorbing film may not only absorb EUV light but also shift the phase of the EUV light. In other words, the absorbing film may be a phase shift film. An opening pattern is formed in the absorbing film. In EUVL, the opening pattern in the absorbing film is transferred to a target substrate such as a semiconductor substrate. Transferring includes reducing and transferring.

[0002] Like a reflective mask, a reflective mask blank has a substrate such as a glass substrate, a multilayer reflective film that reflects EUV light, and an absorbing film that absorbs EUV light, in that order. A reflective mask is obtained by forming an opening pattern in the absorbing film. The manufacturing process for reflective mask blanks and reflective masks includes a cleaning process. This cleaning process may use a chemical solution called SPM (Sulfuric acid-hydrogen peroxide mixture). SPM is an aqueous solution containing sulfuric acid and hydrogen peroxide. Cleaning using SPM may also be performed after the manufacturing of a reflective mask.

[0003] In the thin-film substrate described in Patent Document 1, the thin film contains chromium and nitrogen. Patent Document 1 states that the resistance to SPM can be improved by the thin film having a predetermined crystallinity. The predetermined crystallinity means that the thin film has a crystalline structure in which a peak of diffraction intensity is detected in the diffraction angle 2θ range of 56° to 60° when measured by XRD using CuKα radiation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2020 / 261986 Summary of the Invention [Problem to be solved by the invention]

[0005] The thin film described in Patent Document 1 has high crystallinity in order to improve resistance to SPM. As crystallization progresses and the crystal grains become coarser, the surface roughness of the thin film increases.

[0006] One aspect of the present disclosure provides a technique for reducing the surface roughness of a phase shift film or a conductive film while maintaining the resistance of the phase shift film or the conductive film to SPM. [Means for solving the problem]

[0007] A reflective mask blank according to an embodiment of the present disclosure includes, in this order, a substrate, a multilayer reflective film that reflects EUV light, a protective film that protects the multilayer reflective film, and a phase shift film that shifts the phase of EUV light. The phase shift film contains a Cr compound containing chromium (Cr) and nitrogen (N). The Cr compound has a Cr2p 3 / 2 The difference between the binding energy (BE1) of N1s and the binding energy (BE2) of N1s (ΔBE: ΔBE = BE1 - BE2) is 177.3 eV or less. The Cr compound has a full width at half maximum of a diffraction intensity peak detected in a diffraction angle 2θ range of 35° to 52° of 2.1° or more, as measured by in-plane XRD using CuKα radiation. [Effects of the Invention]

[0008] According to an embodiment of the present disclosure, the surface roughness of a phase shift film or a conductive film can be reduced while maintaining the resistance of the phase shift film or the conductive film to SPM. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing a reflective mask blank according to one embodiment. [Figure 2] FIG. 2 is a flowchart showing a method for manufacturing a reflective mask blank according to one embodiment. [Figure 3] FIG. 3 is a cross-sectional view showing a reflective mask according to an embodiment. [Figure 4] FIG. 4 is a flowchart showing a method for manufacturing a reflective mask according to an embodiment. [Figure 5] FIG. 5(A) is a cross-sectional view showing an example of S201, FIG. 5(B) is a cross-sectional view showing an example of S202, and FIG. 5(C) is a cross-sectional view showing an example of S203. [Figure 6] FIG. 6 is a cross-sectional view showing an example of EUV light reflected by the reflective mask of FIG. [Figure 7] FIG. 7 is a diagram showing an example of the relationship between the ratio (N / Cr) shown in Table 2 and the amount of film loss. [Figure 8] FIG. 8 is a diagram showing the X-ray diffraction patterns of Example 1 and Examples 3 to 6 shown in Table 3. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and their description may be omitted. In the specification, the symbol "to" indicating a numerical range means that the numerical values before and after it are included as the lower and upper limits. The numerical range includes the range rounded up or down.

[0011] In each drawing, the X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to one another. The Z-axis direction is perpendicular to the first main surface 10a of the substrate 10. The X-axis direction is perpendicular to the plane of incidence of the EUV light (the plane including the incident light beam and the reflected light beam). As shown in FIG. 6, the incident light beam is tilted more in the positive Y-axis direction as it moves in the negative Z-axis direction, and the reflected light beam is tilted more in the positive Y-axis direction as it moves in the positive Z-axis direction.

[0012] A reflective mask blank 1 according to one embodiment will be described with reference to FIG. 1. The reflective mask blank 1 includes, for example, a substrate 10, a multilayer reflective film 11, a protective film 12, a phase shift film 13, and a hard mask film 14, in this order. The multilayer reflective film 11, the protective film 12, the phase shift film 13, and the hard mask film 14 are formed in this order on a first main surface 10a of the substrate 10. The multilayer reflective film 11 reflects EUV light. The protective film 12 protects the multilayer reflective film 11 from a first etching gas during processing of the phase shift film 13. The phase shift film 13 absorbs EUV light. The phase shift film 13 not only absorbs EUV light but also shifts the phase of the EUV light. The hard mask film 14 protects a portion of the phase shift film 13 from a first etching gas during processing of the phase shift film 13.

[0013] The reflective mask blank 1 has a conductive film 15 on the side opposite the multilayer reflective film 11 with respect to the substrate 10. That is, the reflective mask blank 1 may have the conductive film 15, substrate 10, multilayer reflective film 11, protective film 12, phase shift film 13, and hard mask film 14, in this order. The conductive film 15 is formed on the second main surface 10b of the substrate 10. The second main surface 10b is the surface facing opposite to the first main surface 10a. The conductive film 15 is used to attach the reflective mask 2 to an electrostatic chuck of an exposure tool.

[0014] The reflective mask blank 1 may further have a functional film not shown in FIG. 1 . For example, the reflective mask blank 1 may have an anti-reflection film (not shown) between the phase shift film 13 and the hard mask film 14. The anti-reflection film improves the optical contrast during inspection of the opening pattern 13op of the phase shift film 13. The reflective mask blank 1 may also have a diffusion barrier film (not shown) between the multilayer reflective film 11 and the protective film 12. The diffusion barrier film prevents metal elements contained in the protective film 12 from diffusing into the multilayer reflective film 11.

[0015] Although not shown, the reflective mask blank 1 may have a buffer film between the protective film 12 and the phase shift film 13. The buffer film protects the protective film 12 from a first etching gas that forms an opening pattern 13op in the phase shift film 13. The buffer film is etched more slowly than the phase shift film 13. Unlike the protective film 12, the buffer film will ultimately have the same opening pattern as the opening pattern 13op of the phase shift film 13.

[0016] Next, a method for manufacturing a reflective mask blank 1 according to one embodiment will be described with reference to Fig. 2. The method for manufacturing a reflective mask blank 1 includes, for example, steps S101 to S106 shown in Fig. 2. In step S101, a substrate 10 is prepared. In step S102, a conductive film 15 is formed on the second main surface 10b of the substrate 10. In step S103, a multilayer reflective film 11 is formed on the first main surface 10a of the substrate 10. In step S104, a protective film 12 is formed on the multilayer reflective film 11. In step S105, a phase shift film 13 is formed on the protective film 12. In step S106, a hard mask film 14 is formed on the phase shift film 13.

[0017] The order of steps S101 to S106 is not limited to the order shown in Fig. 2. For example, the order of step S102 and steps S103 to S106 may be reversed. Furthermore, the method for manufacturing the reflective mask blank 1 does not have to include all of steps S101 to S106. The method for manufacturing the reflective mask blank 1 may further include a step of forming a functional film not shown in Fig. 2.

[0018] Next, a reflective mask 2 according to one embodiment will be described with reference to FIG. 3. The reflective mask 2 includes, for example, the reflective mask blank 1 shown in FIG. 1 and includes an opening pattern 13op in a phase shift film 13. In EUVL, the opening pattern 13op in the phase shift film 13 is transferred to a target substrate such as a semiconductor substrate. Transferring includes reducing and transferring. Note that the hard mask film 14 shown in FIG. 1 is not included in the reflective mask 2.

[0019] Next, a method for manufacturing a reflective mask 2 according to one embodiment will be described with reference to Figures 4 and 5. The method for manufacturing a reflective mask 2 includes steps S201 to S204 shown in Figure 4. In step S201, a reflective mask blank 1 is prepared, as shown in Figure 5(A). The reflective mask blank 1 includes a resist film 16, as shown in Figure 5(A). The resist film 16 is formed on a hard mask film 14. An opening pattern to be transferred to the phase shift film 13 is formed in the resist film 16.

[0020] In step S202, as shown in FIG. 5B, the hard mask film 14 is processed using the resist film 16 having an opening pattern. In the openings in the resist film 16, the hard mask film 14 is exposed to a second etching gas, and the second etching gas etches the hard mask film 14. At the end of step S202, the resist film 16 remains. As a result, the opening pattern of the resist film 16 is transferred to the hard mask film 14.

[0021] The second etching gas is selected depending on the combination of the materials of the resist film 16 and the hard mask film 14, and is not particularly limited, and may include, for example, a fluorine-based gas. The fluorine-based gas may include at least one selected from, for example, CF4 gas, CHF3 gas, C2F6 gas, C3F6 gas, C4F6 gas, C4F8 gas, CH2F2 gas, CH3F gas, C3F8 gas, F2 gas, SF6 gas, and NF3 gas. The second etching gas may include an active gas or an inert gas in addition to the fluorine-based gas. The active gas may include, for example, O2 gas. The inert gas may include, for example, at least one selected from N2 gas, He gas, and Ar gas. The second etching gas is preferably plasmatized.

[0022] In step S203, as shown in FIG. 5C, the phase shift film 13 is processed using the hard mask film 14 having an opening pattern. At the openings in the hard mask film 14, the phase shift film 13 is exposed to a first etching gas, and the first etching gas etches the phase shift film 13. The hard mask film 14 has higher resistance to the first etching gas than the phase shift film 13. At the end of step S203, the hard mask film 14 remains. As a result, the opening pattern of the hard mask film 14 is transferred to the phase shift film 13.

[0023] The first etching gas is selected depending on the combination of the materials of the hard mask film 14 and the phase shift film 13, and is not particularly limited, and may include, for example, a chlorine-based gas and an oxygen-based gas. The chlorine-based gas may include, for example, at least one selected from Cl2 gas, SiCl4 gas, CHCl3 gas, CCl4 gas, and BCl3 gas. The oxygen-based gas may include, for example, at least one selected from O2 gas and O3 gas. The first etching gas may include an inert gas in addition to the chlorine-based gas and the oxygen-based gas. The inert gas may include, for example, at least one selected from N2 gas, He gas, and Ar gas. The first etching gas is preferably plasmatized.

[0024] In step S204, although not shown, the hard mask film 14 is removed. To remove the hard mask film 14, for example, a third etching gas is used. The third etching gas contains, for example, a fluorine-based gas, similar to the second etching gas. The third etching gas is preferably a plasma gas. To remove the hard mask film 14, a chemical solution may be used.

[0025] Next, referring back to FIG. 1, the substrate 10, the multilayer reflective film 11, the protective film 12, the phase shift film 13, the hard mask film 14, and the conductive film 15 will be described in this order.

[0026] The substrate 10 is, for example, a glass substrate. The material of the substrate 10 is preferably quartz glass containing TiO2. Compared to common soda-lime glass, quartz glass has a smaller linear expansion coefficient and undergoes less dimensional change due to temperature changes. The quartz glass may contain 80% to 95% by mass of SiO2 and 4% to 17% by mass of TiO2. When the TiO2 content is 4% to 17% by mass, the linear expansion coefficient is approximately zero near room temperature, and there is almost no dimensional change near room temperature. The quartz glass may contain a third component or impurity other than SiO2 and TiO2. The material of the substrate 10 may also be crystallized glass in which a β-quartz solid solution is precipitated, silicon, metal, or the like.

[0027] The substrate 10 has a first major surface 10a and a second major surface 10b facing opposite to the first major surface 10a. A multilayer reflective film 11 and other components are formed on the first major surface 10a, and a conductive film 15 is formed on the second major surface 10b. In plan view (Z-axis direction), the substrate 10 measures, for example, 152 mm in length and 152 mm in width. The length and width may be 152 mm or greater. The first major surface 10a has a rectangular quality assurance area. The quality assurance area coincides with the exposure area in plan view. The exposure area is the area where the exposure tool is intended to irradiate the phase shift film 13 with EUV light. The size of the quality assurance area is appropriately selected depending on the size of the substrate 10. The quality assurance area preferably has a root-mean-square height (Rq) of 0.15 nm or less and a flatness of 100 nm or less. Furthermore, the quality assurance area preferably does not have defects that would cause phase defects.

[0028] The multilayer reflective film 11 reflects EUV light. The multilayer reflective film 11 is formed by alternately stacking, for example, high-refractive-index layers and low-refractive-index layers. The high-refractive-index layers are made of, for example, silicon (Si), and the low-refractive-index layers are made of, for example, molybdenum (Mo), so a Mo / Si multilayer reflective film is used. Note that other films that can be used as the multilayer reflective film 11 include a Ru / Si multilayer reflective film, a Mo / Be multilayer reflective film, a Mo compound / Si compound multilayer reflective film, a Si / Mo / Ru multilayer reflective film, a Si / Mo / Ru / Mo multilayer reflective film, a Si / Ru / Mo / Ru multilayer reflective film, and a Si / Ru / Mo multilayer reflective film.

[0029] The film thickness of each layer constituting the multilayer reflective film 11 and the number of repeating units of the layers can be appropriately selected according to the material of each layer and the reflectivity with respect to EUV light. When the multilayer reflective film 11 is a Mo / Si multilayer reflective film, in order to achieve a reflectivity of 60% or more with respect to EUV light with an incident angle θ (see FIG. 6) of 6°, a Mo layer with a film thickness of 2.3 ± 0.1 nm and a Si layer with a film thickness of 4.5 ± 0.1 nm may be laminated so that the number of repeating units is 30 or more and 60 or less. The multilayer reflective film 11 preferably has a reflectivity of 60% or more with respect to EUV light with an incident angle θ of 6°. More preferably, the reflectivity is 65% or more.

[0030] Examples of the film formation method for each layer constituting the multilayer reflective film 11 include, for example, DC sputtering method, magnetron sputtering method, or ion beam sputtering method. When forming a Mo / Si multilayer reflective film using the ion beam sputtering method, an example of the film formation conditions for each of the Mo layer and the Si layer is as follows. <Film formation conditions for Si layer> Target: Si target, Sputtering gas: Ar gas, Gas pressure: 1.3×10 -2 Pa ~ 2.7×10 -2 Pa, Ion acceleration voltage: 300 V ~ 1500 V, Film formation rate: 0.030 nm / sec ~ 0.300 nm / sec, Film thickness of Si layer: 4.5 ± 0.1 nm, <Film formation conditions for Mo layer> Target: Mo target, Sputtering gas: Ar gas, Gas pressure: 1.3×10 -2 Pa ~ 2.7×10 -2 Pa, [[ID=三十八]] Ion acceleration voltage: 300 V ~ 1500 V, Film formation rate: 0.030 nm / sec ~ 0.300 nm / sec, Film thickness of Mo layer: 2.3 ± 0.1 nm, <Repeating unit of Si layer and Mo layer> Number of repeating units: 30 to 60 (preferably 40 to 50).

[0031] The protective film 12 is formed between the multilayer reflective film 11 and the phase shift film 13 to protect the multilayer reflective film 11. The protective film 12 protects the multilayer reflective film 11 from the first etching gas when processing the phase shift film 13, i.e., in step S203. The protective film 12 is not removed even when exposed to the first etching gas, but remains on the multilayer reflective film 11.

[0032] The protective film 12 contains at least one element selected from, for example, Ru, Rh, and Si. The protective film 12 preferably contains ruthenium (Ru) as a main component. The Ru content in the protective film 12 is preferably 40 at % or more. When the protective film 12 contains Ru, it may contain only Ru, or it may also contain a Ru compound. The Ru compound may be a Ru alloy. The Ru alloy contains, in addition to Ru, at least one metal element selected from, for example, Rh, Nb, Mo, Ta, Ir, Pd, Zr, Y, and Ti.

[0033] The Ru compound may contain, in addition to Ru, at least one nonmetallic element selected from N, O, C, and B. These nonmetallic elements reduce the resistance of the protective film 12 to the first etching gas, but reduce the crystallinity of the protective film 12, thereby improving the smoothness of the protective film 12. When the Ru compound has a non-crystalline (amorphous) structure or a microcrystalline structure, the X-ray diffraction pattern of the Ru compound does not have a clear peak.

[0034] In this embodiment, the protective film 12 is a single-layer film made of a single layer, but it may also be a multi-layer film having a lower layer and an upper layer. The lower layer of the protective film 12 is a layer formed in contact with the uppermost surface of the multilayer reflective film 11. The upper layer of the protective film 12 is in contact with the lowermost surface of the phase shift film 13. By making the protective film 12 have such a multi-layer structure, materials with excellent predetermined functions can be used for each layer, thereby making the entire protective film 12 multifunctional.

[0035] The upper layer of the protective film 12 preferably contains at least one metal element selected from Ru and Rh, and more preferably contains Rh. The lower layer of the protective film 12 preferably contains at least one element selected from Ru, Rh, Nb, Mo, Zr, Y, and Si, and more preferably contains Ru. When the protective film 12 is a multilayer film, the thickness of the protective film 12 below refers to the total film thickness of the multilayer film. Note that a mixing layer formed by mixing the components contained in the multilayer reflective film 11 and the components contained in the lower layer of the protective film 12 may be formed between the multilayer reflective film 11 and the lower layer of the protective film 12.

[0036] The thickness of the protective film 12 is preferably 1.0 nm to 4.0 nm. If the thickness of the protective film 12 is 1.0 nm or more, the etching resistance is good. Also, if the thickness of the protective film 12 is 4.0 nm or less, the reflectivity with respect to EUV light is good. The thickness of the protective film 12 is more preferably 2.0 nm to 3.5 nm, and even more preferably 2.5 nm to 3.0 nm.

[0037] The density of the protective film 12 is preferably 10.0 g / cm 3 ~14.0 g / cm 3 . If the density of the protective film 12 is 10.0 g / cm 3 or more, the etching resistance is good. Also, if the density of the protective film 12 is 14.0 g / cm 3 or less, the absorption of EUV light by the protective film 12 (and thus the decrease in reflectivity with respect to EUV light) can be suppressed.

[0038] The film formation method of the protective film 12 is, for example, a DC sputtering method, a magnetron sputtering method, or an ion beam sputtering method. When forming a Ru film using the ion beam sputtering method, an example of the film formation conditions is as follows. <Film formation conditions of Ru film> Target: Ru target, Sputtering gas: Ar gas, Gas pressure: 0.010 Pa to 0.020 Pa, Output density of the target: 1.0 W / cm 2 ~8.5 W / cm2 , Deposition rate: 0.01nm / sec~0.10nm / sec, Film thickness: 1nm to 10nm.

[0039] The phase shift film 13 absorbs EUV light. The phase shift film 13 is a film in which an opening pattern 13op is to be formed. The opening pattern 13op is not formed in the manufacturing process of the reflective mask blank 1, but is formed in the manufacturing process of the reflective mask 2. The phase shift film 13 not only absorbs EUV light, but also shifts the phase of the EUV light. The phase shift film shifts the phase of the second EUV light L2 relative to the first EUV light L1 shown in FIG. 6.

[0040] The first EUV light L1 is light that passes through the opening pattern 13op of the phase shift film 13 without being absorbed by the phase shift film 13, is reflected by the multilayer reflective film 11, and passes through the opening pattern 13op of the phase shift film 13 without being absorbed again by the phase shift film 13. The second EUV light L2 is light that passes through the phase shift film 13 while being absorbed by the phase shift film 13, is reflected by the multilayer reflective film 11, and passes through the phase shift film 13 while being absorbed again by the phase shift film 13.

[0041] The phase difference (≧0) between the first EUV light L1 and the second EUV light L2 is, for example, 170° to 250°. The phase of the first EUV light L1 may be ahead or behind the phase of the second EUV light L2. The phase shift film 13 utilizes interference between the first EUV light L1 and the second EUV light L2 to improve the contrast of the transferred image. The transferred image is an image obtained by transferring the opening pattern 13op of the phase shift film 13 onto the target substrate.

[0042] In EUVL, a so-called shadowing effect occurs. The shadowing effect occurs when the incident angle θ of the EUV light is not 0° (for example, 6°), resulting in an area near the sidewall of the opening pattern 13op where the sidewall blocks the EUV light, causing a positional or dimensional shift in the transferred image. In order to reduce the shadowing effect, it is effective to reduce the height of the sidewall of the opening pattern 13op, and it is also effective to thin the phase shift film 13.

[0043] The thickness of the phase shift film 13 is, for example, 85 nm or less, preferably 50 nm or less, in order to reduce the shadowing effect, and is preferably 10 nm or more, more preferably 15 nm or more, in order to ensure a phase difference between the first EUV light L1 and the second EUV light L2.

[0044] To reduce the thickness of the phase shift film 13 to reduce the shadowing effect while maintaining the phase difference between the first EUV light L1 and the second EUV light L2, it is effective to reduce the refractive index n of the phase shift film 13. Furthermore, to reduce the reflectance for the second EUV light L2, it is effective to increase the extinction coefficient k of the phase shift film 13. Thus, the phase shift film 13 is required to have excellent optical properties.

[0045] In this specification, the refractive index n is the refractive index for EUV light (for example, light with a wavelength of 13.5 nm). Also, in this specification, the extinction coefficient k is the extinction coefficient for EUV light (for example, light with a wavelength of 13.5 nm).

[0046] The optical properties (refractive index n and extinction coefficient k) of the phase shift film 13 are taken from the database of the Center for X-Ray Optics, Lawrence Berkeley National Laboratory, or values calculated from the "incident angle dependence" of reflectance described below.

[0047] The incident angle θ of the EUV light, the reflectance R for the EUV light, the refractive index n of the phase shift film 13, and the extinction coefficient k of the phase shift film 13 satisfy the following formula (1). R=|(sinθ-((n+ik) 2 -cos 2 θ) 1 / 2 ) / (sinθ+((n+ik) 2 -cos 2 θ) 1 / 2 )|···(1) A plurality of combinations of the incident angle θ and the reflectance R are measured, and the refractive index n and the extinction coefficient k are calculated by the least squares method so that the error between the plurality of measurement data and Equation (1) is minimized.

[0048] The refractive index n of the phase shift film 13 is preferably 0.900 to 0.960, more preferably 0.910 to 0.940, and even more preferably 0.920 to 0.930. The smaller the refractive index n of the phase shift film 13, the thinner the phase shift film 13 can be made.

[0049] The extinction coefficient k of the phase shift film 13 is preferably 0.020 to 0.060, more preferably 0.030 to 0.050, and even more preferably 0.034 to 0.044. The larger the extinction coefficient k of the phase shift film 13, the smaller the relative reflectance. The relative reflectance is the ratio (%) of the reflectance R2 of the second EUV light L2 to the reflectance R1 of the first EUV light L1.

[0050] The phase shift film 13 preferably contains at least one metal element selected from Cr, Ru, Re, W, Ir, Ta, Nb, Co, Ni, Pt, Pd, Ti, and Zr. These metal elements have a relatively small refractive index, so the thickness of the phase shift film 13 can be reduced while maintaining the phase difference. The phase shift film 13 preferably contains a compound of a metal element. The compound of a metal element preferably contains at least one nonmetal element selected from O, B, C, and N. Adding at least one of these nonmetal elements can suppress crystallization while suppressing deterioration of optical properties.

[0051] The phase shift film 13 preferably contains a Cr compound containing chromium (Cr) and nitrogen (N). The Cr compound preferably contains 60.0 at% to 90.0 at%, more preferably 63.0 at% to 88.0 at%. The Cr compound preferably contains 5.0 at% to 35.0 at%, more preferably 7.0 at% to 25.0 at%.

[0052] The Cr compound preferably satisfies the following (A) and (B): (A) Cr2p measured by XPS 3 / 2 The difference between the binding energy (BE1) of N1s and the binding energy (BE2) of N1s (ΔBE: ΔBE = BE1 - BE2) is 177.3 eV or less. (B) The full width at half maximum (FWHM) of the diffraction intensity peak detected in the diffraction angle 2θ range of 35° to 52° measured by in-plane XRD using CuKα radiation is 2.1° or more.

[0053] Table 1 shows an example of the BE1, BE2, and ΔBE of a Cr compound consisting only of Cr and N. The BE1, BE2, and ΔBE listed in Table 1 are values found in a literature reference (R. Sanjines et al., Thin Solid Films, 1998, Vol. 332, pp. 225-229). As shown in Table 1, when the ratio (N / Cr) of the N content (at%) to the Cr content (at%) changes, that is, when the bonding state between Cr and N changes, the BE1, BE2, and ΔBE change. ΔBE represents the ratio (N / Cr).

[0054] [Table 1]

[0055] If the above (A) is satisfied, that is, if ΔBE is 177.3 eV or less, the covalent bond between Cr and N is strong and the durability against SPM (Sulfuric acid-hydrogen peroxide mixture) is high. SPM is an aqueous solution containing sulfuric acid and hydrogen peroxide. ΔBE is, for example, 177.3 eV or less, preferably 177.1 eV or less, more preferably 177.0 eV or less, and even more preferably 176.8 eV or less. From the viewpoint of resistance to SPM, the lower the ΔBE, the better. However, ΔBE may be 176.0 eV or more.

[0056] If the above condition (B) is satisfied, that is, if the FWHM is 2.1° or more, the crystallinity of the phase shift film 13 is low and the surface roughness of the phase shift film 13 is small. The FWHM is preferably 2.1° or more, and more preferably 3.0° or more. The larger the FWHM, the better, and it is preferable that there is no clear peak.

[0057] As described above, FWHM is measured by in-plane XRD. In-plane XRD tends to have a narrower full width at half maximum of the diffraction intensity peak than out-plane XRD. Since the Cr compound of the present disclosure has low crystallinity, it is measured by in-plane XRD.

[0058] The root mean square height (Rq) of the surface of the phase shift film 13 is preferably 0.400 nm or less. The root mean square height (Rq) is measured in accordance with JIS B0601:2013. The root mean square height (Rq) is preferably 0.400 nm or less, more preferably 0.360 nm or less, even more preferably 0.250 nm or less, and particularly preferably 0.150 nm or less. However, the root mean square height (Rq) may be 0.02 nm or more.

[0059] In addition to the above (A) and (B), the Cr compound preferably satisfies the following (C): (C) The ratio (N / Cr) of the N content (at%) to the Cr content (at%) is 0.08 to 0.40. An example of the relationship between the ratio (N / Cr) and the amount of film loss is shown in Table 2 and FIG. 7.

[0060] [Table 2]

[0061] In Table 2 and Figure 7, "film loss" refers to the amount of thin film thickness loss when a substrate with a thin film made of a Cr compound was immersed in SPM at 100°C for 20 minutes. The SPM used contained 75% concentrated sulfuric acid by volume and 25% hydrogen peroxide solution by volume. The concentrated sulfuric acid used contained 96% sulfuric acid by volume and 4% water by volume. The hydrogen peroxide solution used contained 30% to 35% hydrogen peroxide by volume and 65% to 70% water by volume.

[0062] The smaller the amount of film loss, the better the SPM resistance. From Table 2 and Figure 7, it can be seen that if the ratio (N / Cr) is 0.08 to 0.40, the SPM resistance is good. The ratio (N / Cr) is preferably 0.08 to 0.40, more preferably 0.09 to 0.35, and even more preferably 0.10 to 0.32.

[0063] The Cr compound preferably further contains at least one element X1 selected from Ru, Re, W, Ir, Ta, Nb, Co, Ni, Pt, Pd, Ti, and Zr, in addition to Cr and N. The total content of the element X1 in the Cr compound is preferably 1.0 at% to 25.0 at%, and more preferably 10.0 at% to 20.0 at%.

[0064] The Cr compound preferably further contains at least one element X2 selected from B, C, O, and Si in addition to Cr and N. The total content of the element X2 in the Cr compound is preferably 0.2 at% to 20.0 at%, more preferably 0.5 at% to 18.0 at%.

[0065] The phase shift film 13 is a single-layer film consisting of a single layer in this embodiment, but it may also be a multi-layer film having a lower layer and an upper layer. The lower layer and the upper layer constituting the phase shift film 13 are formed on the protective film 12 in this order. The uppermost layer of the phase shift film 13 is the layer farthest from the protective film 12. The uppermost layer of the phase shift film 13 preferably contains the above-mentioned Cr compound. When the phase shift film 13 is a multi-layer film, the thickness of the phase shift film 13 means the total film thickness of the multi-layer film.

[0066] The film formation method of the phase shift film 13 is, for example, a DC sputtering method, a magnetron sputtering method, an ion beam sputtering method, or the like. The nitrogen content of the phase shift film 13 can be controlled by the content of N2 gas in the sputtering gas. Also, the crystallinity of the phase shift film 13 can be controlled by the gas pressure of the sputtering gas.

[0067] When forming the Cr compound by the sputtering method, it is preferable that the gas pressure of the sputtering gas is higher than 0.10 Pa. The lower the gas pressure, the higher the stability of the Cr compound and the easier the crystallization of the Cr compound. If the gas pressure is higher than 0.10 Pa, the crystallinity of the Cr compound is low and the surface roughness of the phase shift film 13 is small. The gas pressure of the sputtering gas is preferably higher than 0.10 Pa, more preferably 0.11 Pa or more, still more preferably 0.12 Pa or more, and particularly preferably 0.13 Pa or more. Note that the gas pressure of the sputtering gas may be 1.00 Pa or less.

[0068] When forming a CrN film using the magnetron sputtering method, an example of the film formation conditions is as follows. <Film formation conditions of CrN film> Target: Cr target, Sputtering power: 100 W to 1000 W, Sputtering gas: Mixed gas of Ar gas and N2 gas, Volume ratio of N2 gas in sputtering gas (N2 / (Ar + N2)): 0.01 to 0.25, Gas pressure: 0.105 Pa to 1.00 Pa, Film formation temperature: 20°C to 100°C, Film thickness: 15nm~85nm.

[0069] The hard mask film 14 is formed on the opposite side of the phase shift film 13 from the protective film 12, and is used to form an opening pattern 13op in the phase shift film 13. The hard mask film 14 enables the resist film 16 to be made thinner.

[0070] The hard mask film 14 preferably contains at least one metal element or semi-metal element selected from Al, Hf, Y, Cr, Nb, Ti, Mo, Ta, and Si. The hard mask film 14 preferably contains a compound of the above metal element or semi-metal element. The compound preferably contains at least one element selected from O, N, C, and B.

[0071] The thickness of the hard mask film 14 is preferably 2 nm or more and 30 nm or less, more preferably 2 nm or more and 25 nm or less, and further preferably 2 nm or more and 10 nm or less.

[0072] The hard mask film 14 may be formed by, for example, DC sputtering, magnetron sputtering, or ion beam sputtering.

[0073] The conductive film 15 is formed on the opposite side of the substrate 10 from the multilayer reflective film 11, and is used to attach the reflective mask 2 to an electrostatic chuck of an exposure tool. In this embodiment, the conductive film 15 is a single-layer film, but it may also be a multi-layer film having a lower layer and an upper layer.

[0074] From the viewpoints of conductivity and stability, the conductive film 15 preferably contains at least one metal element selected from Cr and Ta. The conductive film 15 preferably contains a compound of the above metal element. The compound preferably contains at least one nonmetal element selected from N, O, C, B, and Si. Like the phase shift film 13, the conductive film 15 preferably contains the above Cr compound.

[0075] The thickness of the conductive film 15 is preferably 20 nm to 400 nm, and more preferably 70 nm to 350 nm. When the conductive film 15 is a multi-layer film, the thickness of the conductive film 15 is the total thickness of the multi-layer film.

[0076] The conductive film 15 can be formed by, for example, DC sputtering, magnetron sputtering, or ion beam sputtering. The nitrogen content of the conductive film 15 can be controlled by the content of N gas in the sputtering gas. Furthermore, the crystallinity of the conductive film 15 can be controlled by the gas pressure of the sputtering gas.

[0077] [Example] The experimental data will be explained below. In Examples 1 to 9, reflective mask blanks 1 were produced with the same configuration except for the configuration of the phase shift film 13 shown in Table 3. Examples 1 to 7 are working examples, and Examples 8 and 9 are comparative examples.

[0078] A SiO2-TiO2-based glass substrate (6-inch (152 mm) square outer diameter, 6.3 mm thick) was prepared as the substrate 10. This glass substrate has a thermal expansion coefficient of 0.02 × 10 at 20 °C. -7 / °C, Young's modulus is 67 GPa, Poisson's ratio is 0.17, and specific stiffness is 3.07 × 10 7 m 2 / s 2 It was.

[0079] A Mo / Si multilayer reflective film was formed as the multilayer reflective film 11. The Mo / Si multilayer reflective film was formed by repeating the process of depositing a Si layer (4.5 nm thick) and a Mo layer (2.3 nm thick) using an ion beam sputtering method 40 times, and then depositing one more Si layer (8.0 nm thick). The total thickness of the Mo / Si multilayer reflective film was 280 nm ((4.5 nm + 2.3 nm) × 40 + 8.0).

[0080] A Ru film was formed by ion beam sputtering as the protective film 12. The Ru film was made of only Ru.

[0081] The phase shift film 13 was formed by magnetron sputtering using a Cr compound film with the chemical composition shown in Table 3. The gas pressure of the sputtering gas was as shown in Table 3. The chemical composition of the Cr compound film was measured using a Hitachi High-Technologies transmission electron microscope (HD-2700) and an Oxford Instruments energy dispersive X-ray analyzer (AZtec Energy TEM Advanced Ultim Max TLE).

[0082] Table 3 shows the evaluation results of the phase shift films 13 obtained in Examples 1 to 9.

[0083] [Table 3]

[0084] The film loss amounts shown in Table 3 are the amounts of thin film thickness reduction when reflective mask blank 1 was immersed in SPM at 100°C for 20 minutes. The SPM used contained 75% by volume of concentrated sulfuric acid and 25% by volume of hydrogen peroxide solution. The concentrated sulfuric acid used contained 96% by volume of sulfuric acid and 4% by volume of water. The hydrogen peroxide solution used contained 30% to 35% by volume of hydrogen peroxide and 65% to 70% by volume of water.

[0085] The Rq values shown in Table 3 were measured in a square area with a side length of 2 μm using a JupiterXR manufactured by Oxford University.

[0086] The FWHM shown in Table 3 was investigated by acquiring X-ray diffraction patterns using a SmartLab manufactured by Rigaku Corporation. As representative examples, the X-ray diffraction patterns of Examples 1 and 3 to 6 are shown in Figure 8. In Figure 8, the X-ray diffraction patterns were acquired by in-plane XRD using CuKα radiation.

[0087] The refractive index n and extinction coefficient k shown in Table 3 were calculated from the "dependence of the incident angle" of the reflectance.

[0088] As shown in Table 3, in Examples 1 to 7, unlike Examples 8 and 9, the sputtering gas pressure was higher than 0.10 Pa, so the FWHM was 2.1° or more. In Examples 1 to 7, the crystallinity was low, so the surface roughness was small, and unlike Examples 8 and 9, Rq was 0.400 nm or less.

[0089] Furthermore, in Examples 1 to 7, ΔBE was 177.3 eV or less, unlike Examples 8 and 9. In Examples 1 to 7, the covalent bond between Cr and N was strong, durability against SPM was high, and the film loss was 2.5 nm or less.

[0090] The reflective mask blank, reflective mask, reflective mask blank manufacturing method, and reflective mask manufacturing method according to the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These naturally fall within the technical scope of the present disclosure. [Explanation of symbols]

[0091] 1. Reflective mask blank 2 Reflective mask 10 Substrate 11 Multilayer reflective film 12 Protective film 13 Phase shift film 15 Conductive film

Claims

1. A reflective mask blank having, in this order: a substrate; a multilayer reflective film that reflects EUV light; a protective film that protects the multilayer reflective film; and a phase shift film that shifts the phase of the EUV light, the phase shift film contains a chromium (Cr) compound containing chromium (Cr) and nitrogen (N); The Cr compound was measured by XPS. ３／２ the difference between the binding energy (BE1) of N1s and the binding energy (BE2) of N1s (ΔBE: ΔBE = BE1 - BE2) is 177.3 eV or less, The Cr compound has a diffraction intensity peak having a full width at half maximum of 2.1° or more when detected at a diffraction angle 2θ in the range of 35° to 52°, as measured by in-plane XRD using CuKα radiation.

2. 2. The reflective mask blank according to claim 1, wherein the Cr compound has a ratio (N / Cr) of the N content (at %) to the Cr content (at %) of 0.08 to 0.

40.

3. 2. The reflective mask blank according to claim 1, wherein the root mean square height (Rq) of the surface of the phase shift film is 0.400 nm or less.

4. 2. The reflective mask blank according to claim 1, wherein the Cr compound further contains at least one element selected from Ru, Re, W, Ir, Ta, Nb, Co, Ni, Pt, Pd, Ti, and Zr.

5. The reflective mask blank according to claim 1 , wherein the Cr compound further contains at least one element selected from the group consisting of B, C, O, and Si.

6. 2. The reflective mask blank according to claim 1, wherein the Cr compound has a refractive index of 0.900 to 0.

960.

7. 2. The reflective mask blank according to claim 1, wherein the Cr compound has an extinction coefficient of 0.020 to 0.

060.

8. A reflective mask blank having, in this order: a conductive film; a substrate; a multilayer reflective film that reflects EUV light; a protective film that protects the multilayer reflective film; and a phase shift film that shifts the phase of EUV light, the conductive film contains a Cr compound containing chromium (Cr) and nitrogen (N), The Cr compound was measured by XPS. ３／２ the difference between the binding energy (BE1) of N1s and the binding energy (BE2) of N1s (ΔBE: ΔBE = BE1 - BE2) is 177.3 eV or less, The Cr compound has a diffraction intensity peak having a full width at half maximum of 1.5° or more when detected in a diffraction angle 2θ range of 35° to 52° as measured by in-plane XRD using CuKα radiation.

9. 9. The reflective mask blank according to claim 8, wherein the Cr compound has a ratio (N / Cr) of the N content (at %) to the Cr content (at %) of 0.08 to 0.

40.

10. 9. The reflective mask blank according to claim 8, wherein the conductive film has a surface with a root mean square height (Rq) of 0.400 nm or less.

11. 9. The reflective mask blank according to claim 8, wherein the Cr compound further contains at least one element selected from Ru, Re, W, Ir, Ta, Nb, Co, Ni, Pt, Pd, Ti, and Zr.

12. The reflective mask blank according to claim 8 , wherein the Cr compound further contains at least one element selected from the group consisting of B, C, O, and Si.

13. 13. The reflective mask blank according to claim 1, wherein the protective film contains at least one element selected from the group consisting of Ru, Rh, and Si.

14. The reflective mask blank according to claim 13 , wherein the protective film contains at least one element selected from N, O, C, and B.

15. a hard mask film on the opposite side of the protective film with respect to the phase shift film; 13. The reflective mask blank according to claim 1, wherein the hard mask film contains at least one element selected from Al, Hf, Y, Cr, Nb, Ti, Mo, Ta, and Si.

16. 16. The reflective mask blank according to claim 15, wherein the hard mask film contains at least one element selected from O, N, C, and B.

17. A reflective mask blank according to claim 1 or 2, A reflective mask including an aperture pattern in the phase shift film.

18. A method for producing a reflective mask blank, comprising the steps of: The Cr compound of the phase shift film is formed by a sputtering method; The method for producing a reflective mask blank, wherein the Cr compound is formed by a sputtering method at a gas pressure higher than 0.10 Pa.

19. A method for producing a reflective mask blank, comprising the steps of: The Cr compound of the conductive film is formed by a sputtering method; The method for producing a reflective mask blank, wherein the Cr compound is formed by a sputtering method at a gas pressure higher than 0.10 Pa.

20. Preparing a reflective mask blank according to any one of claims 1 to 12; forming an opening pattern in the phase shift film; A method for manufacturing a reflective mask, comprising the steps of:

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