WO2024053634A1 - Reflective mask blank, reflective mask, reflective mask blank manufacturing method, and reflective mask manufacturing method - Google Patents

Reflective mask blank, reflective mask, reflective mask blank manufacturing method, and reflective mask manufacturing method Download PDF

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Publication number
WO2024053634A1
WO2024053634A1 PCT/JP2023/032335 JP2023032335W WO2024053634A1 WO 2024053634 A1 WO2024053634 A1 WO 2024053634A1 JP 2023032335 W JP2023032335 W JP 2023032335W WO 2024053634 A1 WO2024053634 A1 WO 2024053634A1
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Prior art keywords
film
phase shift
reflective mask
mask blank
reflective
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PCT/JP2023/032335
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French (fr)
Japanese (ja)
Inventor
大二郎 赤木
健 岡東
啓明 岩岡
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Ａｇｃ株式会社
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Publication of WO2024053634A1 publication Critical patent/WO2024053634A1/en

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/22—Masks or mask blanks for imaging by radiation of 100nm or shorter wavelength, e.g. X-ray masks, extreme ultraviolet [EUV] masks; Preparation thereof
    • G03F1/24—Reflection masks; Preparation thereof
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/26—Phase shift masks [PSM]; PSM blanks; Preparation thereof
    • G03F1/32—Attenuating PSM [att-PSM], e.g. halftone PSM or PSM having semi-transparent phase shift portion; Preparation thereof

Definitions

  • the present disclosure relates to a reflective mask blank, a reflective mask, a method for manufacturing a reflective mask blank, and a method for manufacturing a reflective mask.
  • EUVL EUV lithography
  • EUV includes soft X-rays and vacuum ultraviolet rays, and specifically refers to light with a wavelength of about 0.2 nm to 100 nm.
  • EUV with a wavelength of about 13.5 nm is mainly being considered.
  • a reflective mask is used in EUV lithography.
  • a reflective mask is known to have a structure including a substrate such as a glass substrate, a multilayer reflective film that reflects EUV light, a protective film that protects the multilayer reflective film, and an absorption film that absorbs EUV light in this order. It is being An opening pattern is formed in the absorption film by etching or the like, and the opening pattern is transferred to a target substrate such as a semiconductor substrate.
  • the absorption film may be a phase shift film that shifts EUV light.
  • Patent Document 1 discloses a reflective mask blank equipped with an absorption film mainly composed of chromium (Cr)
  • Patent Document 2 discloses a reflective mask blank equipped with an absorption film mainly composed of tantalum (Ta). Blanks are listed.
  • an object of one embodiment of the present disclosure is to provide a configuration including a phase shift film that can transfer a high-contrast pattern to a target substrate and has excellent processability.
  • a reflective mask blank includes: A reflective mask blank comprising, 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 is made of an Os-based material containing 35 atomic % or more of Os, and has a refractive index n of 0.940 or less and an extinction coefficient k of 0.025 or more with respect to the EUV light. mold mask blank.
  • FIG. 1 is a cross-sectional view showing a reflective mask blank according to one embodiment.
  • FIG. 1 is a cross-sectional view showing a reflective mask according to one embodiment.
  • 3 is a cross-sectional view showing an example of EUV light reflected by the reflective mask of FIG. 2.
  • FIG. It is a figure showing an example of a refractive index and an extinction coefficient of each substance.
  • 1 is a flowchart illustrating a method for manufacturing a reflective mask blank according to an embodiment.
  • 1 is a flowchart illustrating a method for manufacturing a reflective mask according to an embodiment.
  • the X-axis direction, the Y-axis direction, and the Z-axis direction are directions that are orthogonal to each other.
  • the Z-axis direction is a direction perpendicular to the upper surface 10a of the substrate 10.
  • the X-axis direction is a direction perpendicular to the incident plane of EUV light (the plane including the incident light beam and the reflected light beam).
  • the more the incident ray goes in the negative direction of the Z-axis the more it tilts in the positive direction of the Y-axis, and the more the reflected ray goes in the positive direction of the Z-axis, the more it tilts in the positive direction of the Y-axis. do.
  • the reflective mask blank 1 includes at least a substrate 10, a multilayer reflective film 11, a protective film 12, a phase shift film 13, and an etching mask film 14 in this order from bottom to top.
  • the reflective mask blank 1 may further include a functional film not shown in FIG.
  • the reflective mask blank 1 may have a conductive film on the lower side.
  • the conductive film may be formed on the bottom surface 10b of the substrate 10, which is the surface opposite to the top surface 10a. The conductive film is used, for example, to attract the reflective mask 2 to an electrostatic chuck of an exposure device.
  • 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 the etching gas that forms the opening pattern 13a in the phase shift film 13.
  • the buffer film is etched more slowly than the phase shift film 13.
  • the buffer film ultimately has the same opening pattern as the opening pattern 13a of the phase shift film 13.
  • the reflective mask 2 includes, for example, the phase shift film 13 in the reflective mask blank 1 shown in FIG. 1, in which an opening pattern 13a corresponding to a desired semiconductor device pattern is formed. Note that the etching mask film 14 shown in FIG. 1 is removed after the opening pattern 13a is formed in the phase shift film 13. In EUVL, the opening pattern 13a of the phase shift film 13 is transferred to a target substrate such as a semiconductor substrate. Transferring includes reducing and transferring.
  • the substrate 10, multilayer reflective film 11, protective film 12, phase shift film 13, and etching mask film 14 will be explained.
  • the substrate 10 is, for example, a glass substrate.
  • the material of the substrate 10 is preferably silica glass containing TiO 2 .
  • Quartz glass has a smaller coefficient of linear expansion and less dimensional change due to temperature changes than common soda lime glass.
  • the quartz glass may contain 80% to 95% by weight of SiO 2 and 4% to 17% by weight of TiO 2 . When the TiO 2 content is 4% by mass to 17% by mass, the coefficient of linear expansion near room temperature is approximately zero, and almost no dimensional change occurs near room temperature.
  • the quartz glass may contain a third component or impurity other than SiO 2 and TiO 2 . Note that the material of the substrate 10 may be crystallized glass with ⁇ -quartz solid solution precipitated thereon, silicon, metal, or the like.
  • the multilayer reflective film 11 and the like are formed on the upper surface 10a of the substrate 10.
  • the size of the substrate 10 in plan view is, for example, 152 mm in length and 152 mm in width.
  • the vertical dimension and the horizontal dimension may be 152 mm or more.
  • the upper surface 10a and the lower surface 10b of the substrate 10 each have, for example, a quality assurance area in the center.
  • the size of the quality assurance area is, for example, 142 mm in length and 142 mm in width.
  • the quality assurance area of the upper surface 10a preferably has a root mean square roughness Rq of 0.15 nm or less and a flatness of 100 nm or less. Moreover, it is preferable that the quality assurance area of the upper surface 10a does not have defects that cause phase defects.
  • the multilayer reflective film 11 is a film that reflects EUV light, and is, for example, a film in which high refractive index layers and low refractive index layers are alternately laminated.
  • the material of the high refractive index layer is, for example, silicon (Si), and the material of the low refractive index layer is, for example, molybdenum (Mo). Therefore, a Mo/Si multilayer reflective film can be used as the multilayer reflective film.
  • Ru/Si multilayer reflective film Mo/Be multilayer reflective film, Mo compound/Si compound multilayer reflective film, Si/Mo/Ru multilayer reflective film, Si/Mo/Ru/Mo multilayer reflective film, Si/Ru/Mo /Ru multilayer reflective film, Si/Ru/Mo multilayer reflective film, etc. can also be used as the multilayer reflective film 11.
  • each layer constituting the multilayer reflective film 11 and the number of repeating units in the layer can be appropriately selected depending on the material of each layer and the reflectance to EUV light.
  • the thickness must be 2.3 ⁇ to achieve a reflectance of 60% or more for EUV light with an incident angle ⁇ (FIG. 3) of 6°.
  • a 0.1 nm Mo layer and a 4.5 ⁇ 0.1 nm thick Si layer 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 reflectance of 60% or more for EUV light with an incident angle ⁇ of 6°. The reflectance is more preferably 65% or more.
  • the method for forming each layer constituting the multilayer reflective film 11 is, for example, a DC sputtering method, a magnetron sputtering method, or an ion beam sputtering method.
  • a Mo/Si multilayer reflective film using the ion beam sputtering method an example of the film forming conditions for each of the Mo layer and the Si layer is as follows.
  • Si Sputter gas Ar Gas pressure: 1.3 ⁇ 10 -2 Pa to 2.7 ⁇ 10 -2 Pa Ion acceleration voltage: 300V to 1500V Film formation rate: 0.030nm/sec to 0.300nm/sec Thickness of Si layer: 4.5 ⁇ 0.1nm ⁇ Mo layer deposition conditions>
  • Mo Sputter gas Ar Gas pressure: 1.3 ⁇ 10 -2 Pa to 2.7 ⁇ 10 -2 Pa Ion acceleration voltage: 300V to 1500V Film formation rate: 0.030nm/sec to 0.300nm/sec Mo layer thickness: 2.3 ⁇ 0.1nm ⁇ Repeating unit of Si layer and Mo layer> Number of repeating units: 30-60 (preferably 40-50).
  • the protective film 12 is a film that is formed between the multilayer reflective film 11 and the phase shift film 13 and has the function of protecting the multilayer reflective film 11.
  • the protective film 12 protects the multilayer reflective film 11 from the etching gas that forms the opening pattern 13a (FIGS. 2 and 3) in the phase shift film 13. Further, the protective film 12 is not removed during manufacturing of the reflective mask 2, but remains on the multilayer reflective film 11.
  • the protective film 12 does not prevent reflection of EUV light by the multilayer reflective film 11, or minimizes a decrease in reflectance.
  • the material constituting the protective film 12 is not particularly limited, it is preferable that the protective film contains at least one element selected from, for example, Ru, Rh, and Si.
  • the protective film 12 may contain only Rh, or it may contain an Rh compound.
  • the Rh compound may contain at least one element selected from the group consisting of Ru, Nb, Mo, Ta, Ir, Pd, Zr, Y, and Ti.
  • the Rh compound may contain at least one element selected from the group consisting of N, O, C, and B. These elements reduce the resistance of the protective film 12 to the first etching gas, but on the other hand, they improve the smoothness of the protective film 12 by reducing the crystallinity of the protective film 12.
  • the Rh compound has an amorphous structure or a microcrystalline structure, the X-ray diffraction profile of the Rh compound does not have a clear peak.
  • the protective film 12 is a single layer film in this embodiment, it may be a multilayer 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.
  • the upper layer of the protective film 12 preferably contains at least one element selected from Ru and Rh, more preferably contains Rh, and even more preferably contains an Rh compound.
  • 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. Further, the lower layer of the protective film 12 preferably contains at least one element selected from C, N, and B in addition to the above-mentioned at least one element in order to suppress the crystallinity of the protective film 12.
  • the thickness of the protective film 12 described below means the total film thickness of the multilayer film. Note that a mixing layer formed by mixing components contained in the multilayer reflective film 11 and 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.
  • the thickness of the protective film 12 is preferably 1.0 nm to 4.0 nm, more preferably 2.0 nm to 3.5 nm, and even more preferably 2.5 nm to 3.0 nm. If the thickness of the protective film 12 is 1.0 nm or more, the etching resistance is good. Further, when the thickness of the protective film 12 is 4.0 nm or less, the reflectance for EUV light is good.
  • the density of the protective film 12 is preferably 10.0 g/cm 3 to 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. Further, if the density of the protective film 12 is 14.0 g/cm 3 or less, a decrease in reflectance to EUV light can be suppressed.
  • a method for forming the protective film 12 is, for example, a DC sputtering method, a magnetron sputtering method, or an ion beam sputtering method.
  • a Rh film formation conditions is as follows.
  • Rh Sputter gas Ar Gas pressure: 1.0 ⁇ 10 ⁇ 2 Pa to 1.0 ⁇ 10 0 Pa
  • N 2 gas or a mixed gas of Ar gas and N 2 may be used as the sputtering gas.
  • the volume ratio (N 2 /(Ar+N 2 )) of N 2 gas in the sputtering gas is 0.05 or more and 1.0 or less.
  • the phase shift film 13 is a film on which an opening pattern 13a (FIGS. 2 and 3) is formed.
  • the opening pattern 13a 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. For example, the phase shift film shifts the phase of the second EUV light L2 with respect to the first EUV light L1 shown in FIG.
  • the first EUV light L1 is light that passes through the opening pattern 13a without passing through the phase shift film 13, is reflected by the multilayer reflective film 11, and passes through the opening pattern 13a again without passing through the phase shift film 13.
  • the second EUV light L2 is light that is transmitted through the phase shift film 13 while being absorbed by the phase shift film 13, reflected by the multilayer reflective film 11, and transmitted through the phase shift film 13 while being absorbed by the phase shift film 13 again.
  • 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 lead or lag the phase of the second EUV light L2.
  • the phase shift film 13 improves the contrast of the transferred image by utilizing interference between the first EUV light L1 and the second EUV light L2.
  • the transferred image is an image obtained by transferring the opening pattern 13a of the phase shift film 13 onto the target substrate.
  • the shadowing effect is caused by the fact that the incident angle ⁇ of the EUV light is not 0° (for example, 6°), and a region is created near the sidewall of the aperture pattern 13a where the sidewall blocks the EUV light, resulting in a transferred image. This refers to the occurrence of positional or dimensional deviations.
  • it is effective to reduce the height of the side wall of the opening pattern 13a, and it is effective to reduce the thickness of the phase shift film 13.
  • the thickness of the phase shift film 13 is, for example, 60 nm or less, preferably 50 nm or less, in order to reduce the shadowing effect.
  • the thickness of the phase shift film 13 is preferably 20 nm or more, more preferably 30 nm or more in order to ensure a phase difference between the first EUV light L1 and the second EUV light L2.
  • the phase shift film 13 is made of an Os-based material containing 35 atomic % or more of Os.
  • Os is a material with a small refractive index n and a large extinction coefficient k (FIG. 4)
  • the refractive index n of the phase shift film 13 can be reduced and eliminated.
  • the attenuation coefficient k can be increased. This increases the difference between the reflectance of EUV light on the phase shift film 13 and the reflectance from the underlying multilayer reflective film 11 (or from the lower layer including the protective film 12 if the protective film 12 is included).
  • the contrast of the transferred pattern can be improved. Further, since the phase shift film 13 can be made thinner while ensuring a desired phase difference, the above-mentioned shadowing effect is reduced. Therefore, the edges of the optical image pattern to be transferred are not blurred, and high contrast can be obtained even at the edges.
  • the phase shift film 13 made of an Os-based material containing 35 atomic % or more of Os has excellent optical properties similar to Os (the refractive index n is It is easier to process by etching etc. (high processability) compared to other materials such as Ir and Pd (having a small extinction coefficient k and a large extinction coefficient k). Therefore, the phase shift film 13 in this embodiment can be patterned more quickly and with high precision.
  • the content of Os in the phase shift film 13 is preferably such that osmium (Os) is the main component.
  • containing a predetermined element as a main component refers to containing the predetermined element in an amount of 51 atomic % or more. That is, the phase shift film 13 made of an Os-based material containing Os as a main component contains Os at 51 atomic % to 100 atomic %.
  • the content of Os in the phase shift film 13 may be more preferably 60 atomic % or more, still more preferably 70 atomic % or more, and particularly preferably 80 atomic % or more.
  • the etching gas for forming the opening pattern 13a in the phase shift film 13 may be, for example, an oxygen-based gas, a halogen-based gas, or a mixed gas thereof.
  • oxygen-based gas include O 2 gas, O 3 gas, CO 2 gas, NO 2 gas, SO 2 gas, H 2 O gas, or a mixed gas thereof.
  • halogen gas include chlorine gas and fluorine gas.
  • the chlorine-based gas is, for example, Cl 2 gas, SiCl 4 gas, CHCl 3 gas, CCl 4 gas, BCl 3 gas, or a mixed gas thereof.
  • the fluorine-based gas is, for example, CF 4 gas, CHF 3 gas, SF 6 gas, BF 3 gas, XeF 2 gas, or a mixed gas thereof.
  • a mixed gas of an oxygen-based gas and a halogen-based gas particularly a mixed gas of an oxygen-based gas and a chlorine-based gas, is preferred.
  • the mixed gas of oxygen-based gas and halogen-based gas is capable of etching the Os-based material containing Os as a main component according to this embodiment at a high etching rate.
  • the ratio (ER2/ER1) of the etching rate ER2 of the phase shift film 13 to the etching rate ER1 of the protective film 12 is also referred to as the selectivity ratio (ER2/ER1).
  • the selectivity ratio (ER2/ER1) is preferably 5.0 or more, more preferably 10 or more, and still more preferably 30 or more.
  • the selectivity ratio (ER2/ER1) is preferably 200 or less, more preferably 100 or less.
  • the phase shift film 13 may contain only Os, or may contain a metal element, a nonmetal element, or both in addition to Os.
  • the additional element that the phase shift film 13 contains in addition to Os is at least one selected from the group consisting of Ta, Cr, Mo, W, Re, Si, Hf, Ru, O, B, C, and N. It is preferable that there is one.
  • the content of such additional elements in the phase shift film 13 is 1 atomic % to 49 atomic %.
  • phase shift film 13 containing at least one element selected from the group consisting of Ta, Si, and Ru.
  • the content is preferably 1 atomic % to 49 atomic %, and 5 atomic % to 45 atomic %. It is more preferably 5 at % to 40 at %, particularly preferably 5 at % to 35 at %, and most preferably 5 at % to 30 at %.
  • the phase shift film 13 contains at least one element selected from the group consisting of Cr, W, Re, and Ru
  • the optical properties At least the refractive index (n) and/or the extinction coefficient (k) can be adjusted, which can contribute to improving the contrast during pattern transfer as described above.
  • the content is preferably 1 atomic % to 49 atomic %, and 5 atomic % to 45 atomic %. It is more preferably atomic %, further preferably 5 atomic % to 40 atomic %, particularly preferably 5 atomic % to 30 atomic %.
  • the phase shift film 13 contains at least one element selected from the group consisting of O, B, C, and N, crystallization can be suppressed while suppressing deterioration of optical properties, and the opening pattern The roughness of the side wall of 13a can be reduced.
  • the content is preferably 1 atomic % to 20 atomic %, and preferably 2 atomic %. It is more preferable that the content is between 15 at % and 3 at % and even more preferably 10 at %.
  • the refractive index n of the phase shift film 13 is preferably 0.940 or less, more preferably 0.930 or less, and even more preferably 0.920. It is particularly preferably 0.910 or less. The smaller the refractive index n of the phase shift film 13, the thinner the phase shift film 13 can be. Note that the refractive index n of the phase shift film 13 is preferably 0.885 or more. In this specification, the refractive index n is the refractive index for EUV light (for example, light with a wavelength of 13.5 nm).
  • the extinction coefficient k of the phase shift film 13 is preferably 0.025 or more, more preferably 0.030 or more, still more preferably 0.032 or more, and particularly preferably 0.035 or more. be.
  • the extinction coefficient k of the phase shift film 13 is preferably 0.055 or less.
  • the extinction coefficient k is an extinction coefficient for EUV light (for example, light with a wavelength of 13.5 nm).
  • the refractive index n and extinction coefficient k of films such as the phase shift film 13 are obtained from values in the database of Center for X-Ray Optics, Lawrence Berkeley National Laboratory, or from the "incidence angle dependence" of reflectance below. It can be a calculated value.
  • the incident angle ⁇ of the EUV light, the reflectance R for the EUV light, the refractive index n of the film, and the extinction coefficient k of the film satisfy the following formula (1).
  • the refractive index n and the extinction coefficient k can be calculated by the least squares method so that the error between the plurality of measurement data and equation (1) is minimized.
  • the method for forming the phase shift film 13 is, for example, a DC sputtering method, a magnetron sputtering method, an ion beam sputtering method, a plasma CVD method, or the like.
  • the phase shift film 13 additionally contains O
  • the oxygen content of the phase shift film 13 can be controlled by the content of O 2 gas in the sputtering gas.
  • the phase shift film 13 additionally contains N
  • the nitrogen content of the phase shift film 13 can be controlled by the content of N 2 gas in the sputtering gas.
  • an example of film forming conditions is as follows. ⁇ Os film formation conditions> Target: Os Sputter gas: Ar Gas pressure: 0.2Pa Target power density: 1.0W/cm 2 ⁇ 7.0W/cm 2 Film formation rate: 0.020nm/sec to 0.060nm/sec Film thickness: 20nm to 60nm.
  • An etching mask film 14 may be formed on the phase shift film 13. Etching mask film 14 is used to form opening pattern 13a in phase shift film 13. A resist film (not shown) is provided on the etching mask film 14. In the manufacturing process of the reflective mask 2, first a first opening pattern is formed in the resist film, then a second opening pattern is formed in the etching mask film 14 using the first opening pattern, and then a second opening pattern is formed in the etching mask film 14. A third opening pattern 13a is formed in the phase shift film 13 using the following method. The first aperture pattern, the second aperture pattern, and the third aperture pattern 13a have the same dimensions and the same shape in a plan view (as viewed in the Z-axis direction). The etching mask film 14 allows the resist film to be made thinner.
  • the etching mask film 14 contains at least one element selected from the group consisting of Al, Hf, Cr, Nb, Ti, Mo, Ta, and Si.
  • the etching mask film 14 may contain at least one element selected from the group consisting of O, N, and B in addition to the above elements.
  • the thickness of the etching mask film 14 is preferably 1 nm or more and 30 nm or less, more preferably 2 nm or more and 25 nm or less, and even more preferably 2 nm or more and 10 nm or less.
  • a method for forming the etching mask film 14 is, for example, a DC sputtering method, a magnetron sputtering method, or an ion beam sputtering method.
  • one 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.
  • a method for manufacturing a reflective mask blank which includes forming a multilayer reflective film, a protective film, and a phase shift film in this order on a substrate, the phase shift film containing 35 Os atoms. % or more, and has a refractive index n of 0.940 or less and an extinction coefficient k of 0.025 or more with respect to EUV light.
  • the method for manufacturing the reflective mask blank 1 includes steps S101 to S105 shown in FIG. 5, for example.
  • step S101 the substrate 10 is prepared.
  • step S102 a multilayer reflective film 11 is formed on the upper surface 10a of the substrate 10.
  • step S103 a protective film 12 is formed on the multilayer reflective film 11.
  • step S104 the phase shift film 13 is formed on the protective film 12.
  • step S105 an etching mask film 14 is formed on the phase shift film 13.
  • the method for manufacturing the reflective mask blank 1 only needs to include at least steps S101 to S104.
  • the method for manufacturing the reflective mask blank 1 may further include a step of forming a functional film not shown in FIG.
  • one aspect of the present disclosure may be a method for manufacturing a reflective mask, which includes preparing a reflective mask blank and forming an opening pattern in a phase shift film in the reflective mask blank.
  • the method for manufacturing the reflective mask 2 includes steps S201 to S204 shown in FIG.
  • step S201 a reflective mask blank 1 is prepared.
  • step S202 the etching mask film 14 is processed.
  • a resist film (not shown) is provided on the etching mask film 14.
  • step S203 a third opening pattern 13a is formed in the phase shift film 13 using the second opening pattern.
  • step S203 the phase shift film 13 is etched using an etching gas.
  • the resist film and etching mask film 14 are removed.
  • a sulfuric acid-hydrogen peroxide mixture (SPM cleaning solution) is used to remove the resist film.
  • an etching gas is used to remove the etching mask film 14.
  • the etching gas used in step S204 may be the same type of etching gas used in step S203 (formation of opening pattern 13a). Note that the method for manufacturing the reflective mask 2 only needs to include at least steps S201 and S203.
  • Example 1 is an example, and Examples 2 and 3 are comparative examples.
  • Example 1 A reflective mask blank including a substrate, a multilayer reflective film, a protective film, and a phase shift film was manufactured.
  • a substrate a SiO 2 -TiO 2 -based glass substrate (outer size: 6 inches (152 mm) square, thickness: 6.3 mm) was prepared.
  • This glass substrate has a thermal expansion coefficient of 0.02 ⁇ 10 ⁇ 7 /°C at 20°C, a Young's modulus of 67 GPa, a Poisson's ratio of 0.17, and a specific stiffness of 3.07 ⁇ 10 7 m. 2 / s2 .
  • the quality assurance area on the surface (upper surface) of the substrate had a root mean square roughness Rq of 0.15 nm or less and a flatness of 100 nm or less by polishing.
  • a Cr film with a thickness of 100 nm was formed on the back surface (lower surface) of the substrate using a magnetron sputtering method.
  • the sheet resistance of the Cr film was 100 ⁇ / ⁇ .
  • a Mo/Si multilayer reflective film was formed as the multilayer reflective film.
  • the Mo/Si multilayer reflective film is produced by fixing the obtained substrate to a flat electrostatic chuck with the Cr film on the back side facing, and depositing a Si layer (film) on the surface of the substrate using an ion beam sputtering method.
  • the film was formed by repeating 40 times the formation of a Mo layer (thickness: 4.5 nm) and the Mo layer (thickness: 2.3 nm).
  • the total film thickness of the Mo/Si multilayer reflective film was 272 nm ((4.5 nm+2.3 nm) ⁇ 40).
  • a Rh film (thickness: 2.5 nm) was formed as a protective film on the multilayer reflective film.
  • the Rh film was formed using a DC sputtering method.
  • an Os film (thickness: 35 nm) was formed as a phase shift film on the protective film using a DC sputtering method.
  • Example 2 A reflective mask blank was produced in the same manner as in Example 1, except that an Ir film (thickness: 35 nm) was formed in place of the Os film as the phase shift film.
  • Example 3 A reflective mask blank was produced in the same manner as in Example 1, except that a Pd film (thickness: 35 nm) was formed in place of the Os film as the phase shift film.
  • Table 1 shows the reflective mask blanks of Examples 1 to 3 with different types of phase shift films and their characteristics.
  • ⁇ Refractive index n and extinction coefficient k> The refractive index n and extinction coefficient k of the phase shift film shown in Table 1 are the values in the database of the Center for X-Ray Optics, Lawrence Berkeley National Laboratory, or the values calculated from the dependence of the reflectance on the angle of incidence described below. did.
  • the incident angle ⁇ of EUV light, the reflectance R for EUV light, the refractive index n of the phase shift film, and the extinction coefficient k of the phase shift film satisfy the following formula (1).
  • R
  • a plurality of combinations of the incident angle ⁇ and the reflectance R were measured, and the refractive index n and extinction coefficient k were calculated by the least squares method so that the error between the plurality of measurement data and equation (1) was minimized.
  • etching speed The phase shift film was dry etched using a mixed gas of Cl 4 gas and O 2 gas as an etching gas, and the etching rate was measured.
  • ICP inductively coupled plasma
  • the conditions of the apparatus were as follows. ICP antenna bias: 200W Substrate bias: 40W Etching pressure: 3.5Pa Etching gas: Mixed gas of Cl 2 gas and O 2 gas Flow rate of Cl 2 gas: 10 sccm O2 gas flow rate: 10 sccm.
  • the materials of the phase shift films used in Examples 1 to 3 were all materials exhibiting a low refractive index n and a high extinction coefficient k. However, it was found that the phase shift film made of Os (Example 1) can be etched at a higher rate and has higher workability than the phase shift films made of Ir or Pd (Examples 2 and 3).
  • reflective mask blanks were prepared and evaluated in the same manner as in Examples 1 to 3, except that the phase shift film was directly formed on the multilayer reflective film without forming a protective film. Similarly to Example 3, the evaluation results showed that the Os phase shift film was superior.
  • reflective mask blanks were fabricated and evaluated in the same manner as in Examples 1 to 3, except that a silicon wafer was used as the substrate. As in Examples 1 to 3, the Os phase shift film was superior. The evaluation results were as follows.

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Abstract

This reflective mask blank comprises 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 in this order, wherein the phase shift film comprises an Os-based material containing 35 atom% or more of Os, a refractive index n with respect to the EUV light is 0.940 or less, and an extinction coefficient k is 0.025 or more.

Description

反射型マスクブランク、反射型マスク、反射型マスクブランクの製造方法、及び反射型マスクの製造方法Reflective mask blank, reflective mask, method for manufacturing reflective mask blank, and method for manufacturing reflective mask
　本開示は、反射型マスクブランク、反射型マスク、反射型マスクブランクの製造方法、及び反射型マスクの製造方法に関する。 The present disclosure relates to a reflective mask blank, a reflective mask, a method for manufacturing a reflective mask blank, and a method for manufacturing a reflective mask.
　近年、半導体デバイスの微細化に伴い、極端紫外線（Ｅｘｔｒｅｍｅ　Ｕｌｔｒａ－Ｖｉｏｌｅｔ：ＥＵＶ）を用いた露光技術であるＥＵＶリソグラフィー（ＥＵＶＬ）が開発されている。ＥＵＶとは、軟Ｘ線及び真空紫外線を含み、具体的には波長が０．２ｎｍ～１００ｎｍ程度の光のことである。現時点では、１３．５ｎｍ程度の波長のＥＵＶが主に検討されている。 In recent years, with the miniaturization of semiconductor devices, EUV lithography (EUVL), which is an exposure technology using extreme ultraviolet (EUV), has been developed. EUV includes soft X-rays and vacuum ultraviolet rays, and specifically refers to light with a wavelength of about 0.2 nm to 100 nm. At present, EUV with a wavelength of about 13.5 nm is mainly being considered.
　ＥＵＶリソグラフィーには、反射型マスクが用いられる。反射型マスクとしては、ガラス基板等の基板と、ＥＵＶ光を反射する多層反射膜と、多層反射膜を保護する保護膜と、ＥＵＶ光を吸収する吸収膜と、をこの順で有する構成が知られている。吸収膜には、エッチング等により開口パターンが形成されており、当該開口パターンを半導体基板等の対象基板に転写する。吸収膜は、ＥＵＶ光をシフトさせる位相シフト膜であってもよい。 A reflective mask is used in EUV lithography. A reflective mask is known to have a structure including a substrate such as a glass substrate, a multilayer reflective film that reflects EUV light, a protective film that protects the multilayer reflective film, and an absorption film that absorbs EUV light in this order. It is being An opening pattern is formed in the absorption film by etching or the like, and the opening pattern is transferred to a target substrate such as a semiconductor substrate. The absorption film may be a phase shift film that shifts EUV light.
　吸収膜若しくは位相シフト膜の材料として様々な材料が検討されている。例えば、対象基板への高コントラストのパターン転写を実現することを目的として、複屈折率の虚数部の絶対値（消衰係数）が大きい物質を含む材料を利用することが知られている。特許文献１には、クロム（Ｃｒ）を主成分とする吸収膜を備えた反射型マスクブランクスが、また特許文献２には、タンタル（Ｔａ）を主成分とした吸収膜を備えた反射型マスクブランクスが記載されている。 Various materials are being considered as materials for absorption films or phase shift films. For example, it is known to use a material containing a substance with a large absolute value of the imaginary part of the birefringence (extinction coefficient) in order to transfer a pattern with high contrast to a target substrate. Patent Document 1 discloses a reflective mask blank equipped with an absorption film mainly composed of chromium (Cr), and Patent Document 2 discloses a reflective mask blank equipped with an absorption film mainly composed of tantalum (Ta). Blanks are listed.
特開２００７－２７３６５６号公報Japanese Patent Application Publication No. 2007-273656 特開２００７－２７３６７８号公報Japanese Patent Application Publication No. 2007-273678
　しかしながら、消衰係数が大きい材料、特に消衰係数が大きく且つ屈折率が小さい材料には、開口パターンの形成時の加工性が十分でないものもある。そのため、加工条件等によっては、パターンの精度が十分でない、パターン加工時間が長くなってしまう等の不都合が生じることがある。 However, some materials with a large extinction coefficient, particularly materials with a large extinction coefficient and a small refractive index, do not have sufficient workability when forming an aperture pattern. Therefore, depending on processing conditions and the like, problems such as insufficient pattern accuracy and increased pattern processing time may occur.
　よって、本開示の一態様は、対象基板への高コントラストのパターン転写が可能であり、且つ加工性に優れた位相シフト膜を備えた構成を提供することを課題とする。 Therefore, an object of one embodiment of the present disclosure is to provide a configuration including a phase shift film that can transfer a high-contrast pattern to a target substrate and has excellent processability.
　本開示の一態様に係る反射型マスクブランクは、
　基板と、ＥＵＶ光を反射する多層反射膜と、前記多層反射膜を保護する保護膜と、前記ＥＵＶ光の位相をシフトさせる位相シフト膜と、をこの順で有する、反射型マスクブランクであって、前記位相シフト膜は、Ｏｓを３５原子％以上含むＯｓ系材料からなり、前記ＥＵＶ光に対して屈折率ｎが０．９４０以下であり且つ消衰係数ｋが０．０２５以上である、反射型マスクブランク。 A reflective mask blank according to one aspect of the present disclosure includes:
A reflective mask blank comprising, 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 is made of an Os-based material containing 35 atomic % or more of Os, and has a refractive index n of 0.940 or less and an extinction coefficient k of 0.025 or more with respect to the EUV light. mold mask blank.
　本開示の一態様によれば、対象基板への高コントラストのパターン転写が可能であり、且つ加工性に優れた位相シフト膜を備えた構成を提供できる。 According to one aspect of the present disclosure, it is possible to provide a configuration including a phase shift film that enables high-contrast pattern transfer to a target substrate and has excellent processability.
一実施形態に係る反射型マスクブランクを示す断面図である。FIG. 1 is a cross-sectional view showing a reflective mask blank according to one embodiment. 一実施形態に係る反射型マスクを示す断面図である。FIG. 1 is a cross-sectional view showing a reflective mask according to one embodiment. 図２の反射型マスクで反射されるＥＵＶ光の一例を示す断面図である。3 is a cross-sectional view showing an example of EUV light reflected by the reflective mask of FIG. 2. FIG. 各物質の屈折率及び消衰係数の例を示す図である。It is a figure showing an example of a refractive index and an extinction coefficient of each substance. 一実施形態に係る反射型マスクブランクの製造方法を示すフローチャートである。1 is a flowchart illustrating a method for manufacturing a reflective mask blank according to an embodiment. 一実施形態に係る反射型マスクの製造方法を示すフローチャートである。1 is a flowchart illustrating a method for manufacturing a reflective mask according to an embodiment.
　以下、本開示を実施するための形態について図面を参照して説明する。各図面において同一の又は対応する構成には同一の符号を付し、説明を省略することがある。明細書中、数値範囲を示す「～」は、その前後に記載された数値を下限値及び上限値として含むことを意味する。 Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding configurations are denoted by the same reference numerals, and explanations may be omitted. In the specification, "~" indicating a numerical range means that the numerical values written before and after it are included as lower and upper limits.
　図１～図３において、Ｘ軸方向とＹ軸方向とＺ軸方向は互いに直交する方向である。Ｚ軸方向は、基板１０の上面１０ａに対して垂直な方向である。Ｘ軸方向は、ＥＵＶ光の入射面（入射光線と反射光線を含む面）に直交する方向である。図３に示すように、Ｘ軸方向から見たときに、入射光線はＺ軸負方向に向かうほどＹ軸正方向に傾斜し、反射光線はＺ軸正方向に向かうほどＹ軸正方向に傾斜する。 In FIGS. 1 to 3, the X-axis direction, the Y-axis direction, and the Z-axis direction are directions that are orthogonal to each other. The Z-axis direction is a direction perpendicular to the upper surface 10a of the substrate 10. The X-axis direction is a direction perpendicular to the incident plane of EUV light (the plane including the incident light beam and the reflected light beam). As shown in Figure 3, when viewed from the X-axis direction, the more the incident ray goes in the negative direction of the Z-axis, the more it tilts in the positive direction of the Y-axis, and the more the reflected ray goes in the positive direction of the Z-axis, the more it tilts in the positive direction of the Y-axis. do.
　図１を参照して、一実施形態に係る反射型マスクブランク１について説明する。反射型マスクブランク１は、少なくとも、基板１０と、多層反射膜１１と、保護膜１２と、位相シフト膜１３と、エッチングマスク膜１４と、を下から上へこの順番で有する。 With reference to FIG. 1, a reflective mask blank 1 according to an embodiment will be described. The reflective mask blank 1 includes at least a substrate 10, a multilayer reflective film 11, a protective film 12, a phase shift film 13, and an etching mask film 14 in this order from bottom to top.
　反射型マスクブランク１は、図１に図示しない機能膜を更に有してもよい。例えば、反射型マスクブランク１は、下側に導電膜を有してもよい。例えば、導電膜は、基板１０の上面１０ａと反対側の面である下面１０ｂに形成され得る。導電膜は、例えば反射型マスク２を露光装置の静電チャックに吸着するのに用いられる。 The reflective mask blank 1 may further include a functional film not shown in FIG. For example, the reflective mask blank 1 may have a conductive film on the lower side. For example, the conductive film may be formed on the bottom surface 10b of the substrate 10, which is the surface opposite to the top surface 10a. The conductive film is used, for example, to attract the reflective mask 2 to an electrostatic chuck of an exposure device.
　反射型マスクブランク１は、図示しないが、保護膜１２と位相シフト膜１３との間にバッファ膜を有してもよい。バッファ膜は、位相シフト膜１３に開口パターン１３ａを形成するエッチングガスから、保護膜１２を保護する。バッファ膜は、位相シフト膜１３よりも緩やかにエッチングされる。バッファ膜は、保護膜１２とは異なり、最終的に位相シフト膜１３の開口パターン１３ａと同一の開口パターンを有することになる。 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 the etching gas that forms the opening pattern 13a 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 ultimately has the same opening pattern as the opening pattern 13a of the phase shift film 13.
　次に、図２及び図３を参照して、一実施形態に係る反射型マスク２について説明する。反射型マスク２は、例えば、図１に示す反射型マスクブランク１における位相シフト膜１３に、所望される半導体デバイスのパターンに対応する開口パターン１３ａが形成されたものである。なお、図１に示すエッチングマスク膜１４は、位相シフト膜１３に開口パターン１３ａを形成した後に除去される。ＥＵＶＬでは、位相シフト膜１３の開口パターン１３ａが、半導体基板等の対象基板に転写される。転写することは、縮小して転写することを含む。 Next, a reflective mask 2 according to an embodiment will be described with reference to FIGS. 2 and 3. The reflective mask 2 includes, for example, the phase shift film 13 in the reflective mask blank 1 shown in FIG. 1, in which an opening pattern 13a corresponding to a desired semiconductor device pattern is formed. Note that the etching mask film 14 shown in FIG. 1 is removed after the opening pattern 13a is formed in the phase shift film 13. In EUVL, the opening pattern 13a of the phase shift film 13 is transferred to a target substrate such as a semiconductor substrate. Transferring includes reducing and transferring.
　以下、基板１０、多層反射膜１１、保護膜１２、位相シフト膜１３、及びエッチングマスク膜１４について説明する。 Hereinafter, the substrate 10, multilayer reflective film 11, protective film 12, phase shift film 13, and etching mask film 14 will be explained.
　基板１０は、例えばガラス基板である。基板１０の材質は、ＴｉＯ２を含有する石英ガラスが好ましい。石英ガラスは、一般的なソーダライムガラスに比べて、線膨張係数が小さく、温度変化による寸法変化が小さい。石英ガラスは、ＳｉＯ２を８０質量％～９５質量％、ＴｉＯ２を４質量％～１７質量％含んでよい。ＴｉＯ２含有量が４質量％～１７質量％であると、室温付近での線膨張係数が略ゼロであり、室温付近での寸法変化がほとんど生じない。石英ガラスは、ＳｉＯ２及びＴｉＯ２以外の第三成分又は不純物を含んでもよい。なお、基板１０の材質は、β石英固溶体を析出した結晶化ガラス、シリコン、又は金属等であってもよい。 The substrate 10 is, for example, a glass substrate. The material of the substrate 10 is preferably silica glass containing TiO 2 . Quartz glass has a smaller coefficient of linear expansion and less dimensional change due to temperature changes than common soda lime glass. The quartz glass may contain 80% to 95% by weight of SiO 2 and 4% to 17% by weight of TiO 2 . When the TiO 2 content is 4% by mass to 17% by mass, the coefficient of linear expansion near room temperature is approximately zero, and almost no dimensional change occurs near room temperature. The quartz glass may contain a third component or impurity other than SiO 2 and TiO 2 . Note that the material of the substrate 10 may be crystallized glass with β-quartz solid solution precipitated thereon, silicon, metal, or the like.
　上述のように、基板１０の上面１０ａには、多層反射膜１１等が形成される。平面視（Ｚ軸方向視）にて基板１０のサイズは、例えば縦１５２ｍｍ、横１５２ｍｍである。縦寸法及び横寸法は、１５２ｍｍ以上であってもよい。基板１０の上面１０ａ及び下面１０ｂは、各々の中央に、例えば品質保証領域を有する。品質保証領域のサイズは、例えば縦１４２ｍｍ、横１４２ｍｍである。上面１０ａの品質保証領域は、０．１５ｎｍ以下の二乗平均平方根粗さＲｑと、１００ｎｍ以下の平坦度とを有することが好ましい。また、上面１０ａの品質保証領域は、位相欠陥を生じさせる欠点を有しないことが好ましい。 As described above, the multilayer reflective film 11 and the like are formed on the upper surface 10a of the substrate 10. The size of the substrate 10 in plan view (viewed in the Z-axis direction) is, for example, 152 mm in length and 152 mm in width. The vertical dimension and the horizontal dimension may be 152 mm or more. The upper surface 10a and the lower surface 10b of the substrate 10 each have, for example, a quality assurance area in the center. The size of the quality assurance area is, for example, 142 mm in length and 142 mm in width. The quality assurance area of the upper surface 10a preferably has a root mean square roughness Rq of 0.15 nm or less and a flatness of 100 nm or less. Moreover, it is preferable that the quality assurance area of the upper surface 10a does not have defects that cause phase defects.
　多層反射膜１１は、ＥＵＶ光を反射する膜であり、例えば高屈折率層と低屈折率層とを交互に積層したものである。高屈折率層の材質は例えばシリコン（Ｓｉ）であり、低屈折率層の材質は例えばモリブデン（Ｍｏ）である。よって、多層反射膜としては、Ｍｏ／Ｓｉ多層反射膜を用いることができる。なお、Ｒｕ／Ｓｉ多層反射膜、Ｍｏ／Ｂｅ多層反射膜、Ｍｏ化合物／Ｓｉ化合物多層反射膜、Ｓｉ／Ｍｏ／Ｒｕ多層反射膜、Ｓｉ／Ｍｏ／Ｒｕ／Ｍｏ多層反射膜、Ｓｉ／Ｒｕ／Ｍｏ／Ｒｕ多層反射膜、Ｓｉ／Ｒｕ／Ｍｏ多層反射膜等も、多層反射膜１１として使用可能である。 The multilayer reflective film 11 is a film that reflects EUV light, and is, for example, a film in which high refractive index layers and low refractive index layers are alternately laminated. The material of the high refractive index layer is, for example, silicon (Si), and the material of the low refractive index layer is, for example, molybdenum (Mo). Therefore, a Mo/Si multilayer reflective film can be used as the multilayer reflective film. In addition, Ru/Si multilayer reflective film, Mo/Be multilayer reflective film, Mo compound/Si compound multilayer reflective film, Si/Mo/Ru multilayer reflective film, Si/Mo/Ru/Mo multilayer reflective film, Si/Ru/Mo /Ru multilayer reflective film, Si/Ru/Mo multilayer reflective film, etc. can also be used as the multilayer reflective film 11.
　多層反射膜１１を構成する各層の厚み及び層の繰り返し単位の数は、各層の材質、及びＥＵＶ光に対する反射率に応じて適宜選択できる。多層反射膜１１は、Ｍｏ／Ｓｉ多層反射膜である場合、入射角θ（図３）が６°であるＥＵＶ光に対して６０％以上の反射率を達成するには、厚み２．３±０．１ｎｍのＭｏ層と、厚み４．５±０．１ｎｍのＳｉ層とを繰り返し単位数が３０以上６０以下になるように積層すればよい。多層反射膜１１は、入射角θが６°であるＥＵＶ光に対して６０％以上の反射率を有することが好ましい。反射率は、より好ましくは６５％以上である。 The thickness of each layer constituting the multilayer reflective film 11 and the number of repeating units in the layer can be appropriately selected depending on the material of each layer and the reflectance to EUV light. When the multilayer reflective film 11 is a Mo/Si multilayer reflective film, the thickness must be 2.3± to achieve a reflectance of 60% or more for EUV light with an incident angle θ (FIG. 3) of 6°. A 0.1 nm Mo layer and a 4.5±0.1 nm thick Si layer 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 reflectance of 60% or more for EUV light with an incident angle θ of 6°. The reflectance is more preferably 65% or more.
　多層反射膜１１を構成する各層の成膜方法は、例えば、ＤＣスパッタリング法、マグネトロンスパッタリング法、又はイオンビームスパッタリング法などである。イオンビームスパッタリング法を用いてＭｏ／Ｓｉ多層反射膜を形成する場合、Ｍｏ層とＳｉ層の各々の成膜条件の一例は下記の通りである。
＜Ｓｉ層の成膜条件＞
ターゲット：Ｓｉ
スパッタガス：Ａｒ
ガス圧：１．３×１０－２Ｐａ～２．７×１０－２Ｐａ
イオン加速電圧：３００Ｖ～１５００Ｖ
成膜速度：０．０３０ｎｍ／ｓｅｃ～０．３００ｎｍ／ｓｅｃ
Ｓｉ層の厚み：４．５±０．１ｎｍ
＜Ｍｏ層の成膜条件＞
ターゲット：Ｍｏ
スパッタガス：Ａｒ
ガス圧：１．３×１０－２Ｐａ～２．７×１０－２Ｐａ
イオン加速電圧：３００Ｖ～１５００Ｖ
成膜速度：０．０３０ｎｍ／ｓｅｃ～０．３００ｎｍ／ｓｅｃ
Ｍｏ層の厚み：２．３±０．１ｎｍ
＜Ｓｉ層とＭｏ層の繰り返し単位＞
繰り返し単位数：３０～６０（好ましくは４０～５０）。 The method for forming each layer constituting the multilayer reflective film 11 is, for example, a DC sputtering method, a magnetron sputtering method, or an ion beam sputtering method. When forming a Mo/Si multilayer reflective film using the ion beam sputtering method, an example of the film forming conditions for each of the Mo layer and the Si layer is as follows.
<Si layer deposition conditions>
Target: Si
Sputter gas: Ar
Gas pressure: 1.3×10 -2 Pa to 2.7×10 -2 Pa
Ion acceleration voltage: 300V to 1500V
Film formation rate: 0.030nm/sec to 0.300nm/sec
Thickness of Si layer: 4.5±0.1nm
<Mo layer deposition conditions>
Target: Mo
Sputter gas: Ar
Gas pressure: 1.3×10 -2 Pa to 2.7×10 -2 Pa
Ion acceleration voltage: 300V to 1500V
Film formation rate: 0.030nm/sec to 0.300nm/sec
Mo layer thickness: 2.3±0.1nm
<Repeating unit of Si layer and Mo layer>
Number of repeating units: 30-60 (preferably 40-50).
　保護膜１２は、多層反射膜１１と位相シフト膜１３の間に形成され、多層反射膜１１を保護する機能を有する膜である。保護膜１２は、位相シフト膜１３に開口パターン１３ａ（図２及び図３）を形成するエッチングガスから多層反射膜１１を保護する。また、保護膜１２は、反射型マスク２の製造の際に除去されず、多層反射膜１１の上に留まるものである。保護膜１２は、多層反射膜１１によるＥＵＶ光の反射を妨げないか、反射率の低下を最小限に抑える。 The protective film 12 is a film that is formed between the multilayer reflective film 11 and the phase shift film 13 and has the function of protecting the multilayer reflective film 11. The protective film 12 protects the multilayer reflective film 11 from the etching gas that forms the opening pattern 13a (FIGS. 2 and 3) in the phase shift film 13. Further, the protective film 12 is not removed during manufacturing of the reflective mask 2, but remains on the multilayer reflective film 11. The protective film 12 does not prevent reflection of EUV light by the multilayer reflective film 11, or minimizes a decrease in reflectance.
　保護膜１２を構成する材料は特に限定されないが、保護膜は、例えばＲｕ、Ｒｈ及びＳｉから選択される少なくとも１つの元素を含有すると好ましい。保護膜１２は、Ｒｈを含有する場合、Ｒｈのみを含有してもよいが、Ｒｈ化合物を有してもよい。Ｒｈ化合物は、Ｒｈに加えて、Ｒｕ、Ｎｂ、Ｍｏ、Ｔａ、Ｉｒ、Ｐｄ、Ｚｒ、Ｙ及びＴｉからなる群から選択される少なくとも１つの元素を含有してもよい。 Although the material constituting the protective film 12 is not particularly limited, it is preferable that the protective film contains at least one element selected from, for example, Ru, Rh, and Si. When the protective film 12 contains Rh, it may contain only Rh, or it may contain an Rh compound. In addition to Rh, the Rh compound may contain at least one element selected from the group consisting of Ru, Nb, Mo, Ta, Ir, Pd, Zr, Y, and Ti.
　Ｒｈ化合物は、Ｒｈに加えて、Ｎ、Ｏ、Ｃ及びＢからなる群から選択される少なくとも１つの元素を含有してもよい。これらの元素は、保護膜１２の第１エッチングガスに対する耐性を低下させてしまう反面、保護膜１２の結晶性を低下させることで保護膜１２の平滑性を向上する。Ｒｈ化合物が非結晶構造、又は微結晶構造を有する場合、Ｒｈ化合物のＸ線回折プロファイルは明瞭なピークを有しない。 In addition to Rh, the Rh compound may contain at least one element selected from the group consisting of N, O, C, and B. These elements reduce the resistance of the protective film 12 to the first etching gas, but on the other hand, they improve the smoothness of the protective film 12 by reducing the crystallinity of the protective film 12. When the Rh compound has an amorphous structure or a microcrystalline structure, the X-ray diffraction profile of the Rh compound does not have a clear peak.
　保護膜１２は、本実施形態では単一の層からなる膜であるが、下層及び上層を有する多層膜であってもよい。保護膜１２の下層は、多層反射膜１１の最上面に接触して形成された層である。保護膜１２の上層は、位相シフト膜１３の最下面に接触している。このように、保護膜１２を複数層構造とすることで、所定の機能に優れた材料を各層に使用できるので、保護膜１２全体の多機能化を図ることができる。 Although the protective film 12 is a single layer film in this embodiment, it may be a multilayer 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 a multi-layer structure in this way, a material excellent in a predetermined function can be used for each layer, so that the entire protective film 12 can be made multifunctional.
　保護膜１２の上層は、Ｒｕ及びＲｈから選択される少なくとも１つの元素を含むことが好ましく、Ｒｈを含むことがより好ましく、Ｒｈ化合物を含むことがさらに好ましい。保護膜１２の下層は、Ｒｕ、Ｒｈ、Ｎｂ、Ｍｏ、Ｚｒ、Ｙ及びＳｉから選択される少なくとも１つの元素を含むことが好ましく、Ｒｕを含むことがより好ましい。また、保護膜１２の下層は、保護膜１２の結晶性抑制のために、上記の少なくとも１つの元素に加えて、さらにＣ、Ｎ及びＢから選択される少なくとも１つの元素を含むことが好ましい。保護膜１２が多層膜である場合、下記の保護膜１２の厚みとは多層膜の合計膜厚を意味する。なお、多層反射膜１１と保護膜１２の下層の間に、多層反射膜１１に含まれる成分と保護膜１２の下層に含まれる成分が混合し形成されたミキシング層が形成されてもよい。 The upper layer of the protective film 12 preferably contains at least one element selected from Ru and Rh, more preferably contains Rh, and even more preferably contains an Rh compound. 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. Further, the lower layer of the protective film 12 preferably contains at least one element selected from C, N, and B in addition to the above-mentioned at least one element in order to suppress the crystallinity of the protective film 12. When the protective film 12 is a multilayer film, the thickness of the protective film 12 described below means the total film thickness of the multilayer film. Note that a mixing layer formed by mixing components contained in the multilayer reflective film 11 and 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.
　保護膜１２の厚みは、好ましくは１．０ｎｍ～４．０ｎｍであり、より好ましくは２．０ｎｍ～３．５ｎｍであり、さらに好ましくは２．５ｎｍ～３．０ｎｍである。保護膜１２の厚みが１．０ｎｍ以上であれば、エッチング耐性が良好である。また、保護膜１２の厚みが４．０ｎｍ以下であれば、ＥＵＶ光に対する反射率が良好である。 The thickness of the protective film 12 is preferably 1.0 nm to 4.0 nm, more preferably 2.0 nm to 3.5 nm, and even more preferably 2.5 nm to 3.0 nm. If the thickness of the protective film 12 is 1.0 nm or more, the etching resistance is good. Further, when the thickness of the protective film 12 is 4.0 nm or less, the reflectance for EUV light is good.
　保護膜１２の密度は、好ましくは１０．０ｇ／ｃｍ３～１４．０ｇ／ｃｍ３である。保護膜１２の密度が１０．０ｇ／ｃｍ３以上であれば、エッチング耐性が良い。また、保護膜１２の密度が１４．０ｇ／ｃｍ３以下であれば、ＥＵＶ光に対する反射率の低下を抑制できる。 The density of the protective film 12 is preferably 10.0 g/cm 3 to 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. Further, if the density of the protective film 12 is 14.0 g/cm 3 or less, a decrease in reflectance to EUV light can be suppressed.
　保護膜１２の成膜方法は、例えば、ＤＣスパッタリング法、マグネトロンスパッタリング法又はイオンビームスパッタリング法などである。ＤＣスパッタリング法を用いてＲｈ膜を形成する場合、成膜条件の一例は下記の通りである。
＜Ｒｈ膜の成膜条件＞
ターゲット：Ｒｈ
スパッタガス：Ａｒ
ガス圧：１．０×１０－２Ｐａ～１．０×１００Ｐａ
ターゲットの出力密度：１．０Ｗ／ｃｍ２～８．５Ｗ／ｃｍ２
成膜速度：０．０２０ｎｍ／ｓｅｃ～１．０００ｎｍ／ｓｅｃ
膜厚：１ｎｍ～１０ｎｍ。 A method for forming the protective film 12 is, for example, a DC sputtering method, a magnetron sputtering method, or an ion beam sputtering method. When forming a Rh film using the DC sputtering method, an example of film forming conditions is as follows.
<Rh film formation conditions>
Target: Rh
Sputter gas: Ar
Gas pressure: 1.0×10 −2 Pa to 1.0×10 0 Pa
Target power density: 1.0W/cm 2 ~8.5W/cm 2
Film formation rate: 0.020nm/sec to 1.000nm/sec
Film thickness: 1 nm to 10 nm.
　なお、Ｒｈ膜を形成する場合、スパッタガスとして、Ｎ２ガスまたはＡｒガスとＮ２の混合ガスを使用してもよい。スパッタガス中のＮ２ガスの体積比（Ｎ２／（Ａｒ＋Ｎ２））は０．０５以上１．０以下である。 Note that when forming the Rh film, N 2 gas or a mixed gas of Ar gas and N 2 may be used as the sputtering gas. The volume ratio (N 2 /(Ar+N 2 )) of N 2 gas in the sputtering gas is 0.05 or more and 1.0 or less.
　位相シフト膜１３は、開口パターン１３ａ（図２及び図３）が形成される膜である。開口パターン１３ａは、反射型マスクブランク１の製造工程では形成されずに、反射型マスク２の製造工程で形成される。位相シフト膜１３は、ＥＵＶ光を吸収するだけではなく、ＥＵＶ光の位相をシフトさせる。例えば、位相シフト膜は、図３に示す第１ＥＵＶ光Ｌ１に対して、第２ＥＵＶ光Ｌ２の位相をシフトさせる。 The phase shift film 13 is a film on which an opening pattern 13a (FIGS. 2 and 3) is formed. The opening pattern 13a 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. For example, the phase shift film shifts the phase of the second EUV light L2 with respect to the first EUV light L1 shown in FIG.
　第１ＥＵＶ光Ｌ１は、位相シフト膜１３を透過することなく開口パターン１３ａを通過し、多層反射膜１１で反射され、再び位相シフト膜１３を透過することなく開口パターン１３ａを通過した光である。第２ＥＵＶ光Ｌ２は、位相シフト膜１３に吸収されながら位相シフト膜１３を透過し、多層反射膜１１で反射され、再び位相シフト膜１３に吸収されながら位相シフト膜１３を透過した光である。 The first EUV light L1 is light that passes through the opening pattern 13a without passing through the phase shift film 13, is reflected by the multilayer reflective film 11, and passes through the opening pattern 13a again without passing through the phase shift film 13. The second EUV light L2 is light that is transmitted through the phase shift film 13 while being absorbed by the phase shift film 13, reflected by the multilayer reflective film 11, and transmitted through the phase shift film 13 while being absorbed by the phase shift film 13 again.
　第１ＥＵＶ光Ｌ１と第２ＥＵＶ光Ｌ２の位相差（≧０）は、例えば１７０°～２５０°である。第１ＥＵＶ光Ｌ１の位相が、第２ＥＵＶ光Ｌ２の位相よりも、進んでいてもよいし、遅れていてもよい。位相シフト膜１３は、第１ＥＵＶ光Ｌ１と第２ＥＵＶ光Ｌ２の干渉を利用して、転写像のコントラストを向上する。転写像は、位相シフト膜１３の開口パターン１３ａを対象基板に転写した像である。 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 lead or lag the phase of the second EUV light L2. The phase shift film 13 improves the contrast of the transferred image by utilizing interference between the first EUV light L1 and the second EUV light L2. The transferred image is an image obtained by transferring the opening pattern 13a of the phase shift film 13 onto the target substrate.
　ＥＵＶリソグラフィーにおいては、いわゆる射影効果（シャドーイング効果）が生じる。シャドーイング効果とは、ＥＵＶ光の入射角θが０°ではない（例えば６°である）ことに起因して、開口パターン１３ａの側壁付近に、側壁によってＥＵＶ光を遮る領域が生じ、転写像の位置ずれまたは寸法ずれが生じることをいう。シャドーイング効果を低減するには、開口パターン１３ａの側壁の高さを低くすることが有効であり、位相シフト膜１３の薄化が有効である。 In EUV lithography, a so-called projection effect (shadowing effect) occurs. The shadowing effect is caused by the fact that the incident angle θ of the EUV light is not 0° (for example, 6°), and a region is created near the sidewall of the aperture pattern 13a where the sidewall blocks the EUV light, resulting in a transferred image. This refers to the occurrence of positional or dimensional deviations. In order to reduce the shadowing effect, it is effective to reduce the height of the side wall of the opening pattern 13a, and it is effective to reduce the thickness of the phase shift film 13.
　位相シフト膜１３の膜厚は、シャドーイング効果を低減すべく、例えば６０ｎｍ以下であり、好ましくは５０ｎｍ以下である。位相シフト膜１３の膜厚は、第１ＥＵＶ光Ｌ１と第２ＥＵＶ光Ｌ２の位相差を確保すべく、好ましくは２０ｎｍ以上であり、より好ましくは３０ｎｍ以上である。 The thickness of the phase shift film 13 is, for example, 60 nm or less, preferably 50 nm or less, in order to reduce the shadowing effect. The thickness of the phase shift film 13 is preferably 20 nm or more, more preferably 30 nm or more in order to ensure a phase difference between the first EUV light L1 and the second EUV light L2.
　本実施形態では、位相シフト膜１３は、Ｏｓを３５原子％以上含むＯｓ系材料からなる。 In this embodiment, the phase shift film 13 is made of an Os-based material containing 35 atomic % or more of Os.
　Ｏｓは、屈折率ｎが小さく且つ消衰係数ｋが大きい材料であるので（図４）、位相シフト膜１３にＯｓ系材料を利用することで、位相シフト膜１３の屈折率ｎを小さく且つ消衰係数ｋを大きくすることができる。これにより、ＥＵＶ光の位相シフト膜１３での反射率と、その下層の多層反射膜１１からの（保護膜１２を含む場合には保護膜１２を含む下層からの）反射率との差を大きくすることができ、転写されるパターンのコントラストを向上できる。また、所望の位相差を確保しつつ位相シフト膜１３を薄化できるので、上述のシャドーイング効果が低減される。よって、転写される光学像パターンのエッジがぼかされることなく、エッジにおいても高いコントラストを得ることができる。 Since Os is a material with a small refractive index n and a large extinction coefficient k (FIG. 4), by using an Os-based material for the phase shift film 13, the refractive index n of the phase shift film 13 can be reduced and eliminated. The attenuation coefficient k can be increased. This increases the difference between the reflectance of EUV light on the phase shift film 13 and the reflectance from the underlying multilayer reflective film 11 (or from the lower layer including the protective film 12 if the protective film 12 is included). The contrast of the transferred pattern can be improved. Further, since the phase shift film 13 can be made thinner while ensuring a desired phase difference, the above-mentioned shadowing effect is reduced. Therefore, the edges of the optical image pattern to be transferred are not blurred, and high contrast can be obtained even at the edges.
　さらに、Ｏｓは、容易に揮発性化合物を形成できる材料であるため、Ｏｓを３５原子％以上含むＯｓ系材料からなる位相シフト膜１３は、Ｏｓと同様に光学特性に優れた（屈折率ｎが小さく且つ消衰係数ｋが大きい）他の材料、例えばＩｒ、Ｐｄ等と比較して、エッチング等による加工がしやすい（加工性が高い）。よって、本実施形態における位相シフト膜１３は、より迅速で且つ高精度なパターン加工が可能である。 Furthermore, since Os is a material that can easily form volatile compounds, the phase shift film 13 made of an Os-based material containing 35 atomic % or more of Os has excellent optical properties similar to Os (the refractive index n is It is easier to process by etching etc. (high processability) compared to other materials such as Ir and Pd (having a small extinction coefficient k and a large extinction coefficient k). Therefore, the phase shift film 13 in this embodiment can be patterned more quickly and with high precision.
　位相シフト膜１３中のＯｓの含有量は、オスミウム（Ｏｓ）を主成分とすることが好ましい。本明細書において、「所定元素を主成分とする」とは、所定元素を５１原子％以上で含有することを指す。すなわち、Ｏｓを主成分とするＯｓ系材料からなる位相シフト膜１３は、Ｏｓを５１原子％～１００原子％で含有するものである。 The content of Os in the phase shift film 13 is preferably such that osmium (Os) is the main component. In this specification, "containing a predetermined element as a main component" refers to containing the predetermined element in an amount of 51 atomic % or more. That is, the phase shift film 13 made of an Os-based material containing Os as a main component contains Os at 51 atomic % to 100 atomic %.
　また位相シフト膜１３中のＯｓの含有量は、より好ましくは６０原子％以上、さらに好ましくは７０原子％以上、特に好ましくは８０原子％以上であってよい。Ｏｓの含有量が多いほど、転写パターンのコントラストが高く、且つ加工性の高い構成を得ることができる。 Further, the content of Os in the phase shift film 13 may be more preferably 60 atomic % or more, still more preferably 70 atomic % or more, and particularly preferably 80 atomic % or more. The higher the content of Os, the higher the contrast of the transferred pattern and the higher the processability.
　位相シフト膜１３における開口パターン１３ａを形成するためのエッチングガスは、例えば酸素系ガス、ハロゲン系ガス、又はこれらの混合ガスであってよい。酸素系ガスとしては、例えばＯ２ガス、Ｏ３ガス、ＣＯ２ガス、ＮＯ２ガス、ＳＯ２ガス、Ｈ２Ｏガス又はこれらの混合ガスが挙げられる。ハロゲン系ガスとしては、塩素系ガスと、フッ素系ガスと、が挙げられる。塩素系ガスは、例えばＣｌ２ガス、ＳｉＣｌ４ガス、ＣＨＣｌ３ガス、ＣＣｌ４ガス、ＢＣｌ３ガス又はこれらの混合ガスである。フッ素系ガスは、例えばＣＦ４ガス、ＣＨＦ３ガス、ＳＦ６ガス、ＢＦ３ガス、ＸｅＦ２ガス又はこれらの混合ガスである。これらのうち、酸素系ガスとハロゲン系ガスとの混合ガス、特に酸素系ガスと塩素系ガスとの混合ガスが好ましい。酸素系ガスとハロゲン系ガスとの混合ガスは、本実施形態によるＯｓを主成分とするＯｓ系材料に対し、高いエッチング速度でのエッチングが可能である。 The etching gas for forming the opening pattern 13a in the phase shift film 13 may be, for example, an oxygen-based gas, a halogen-based gas, or a mixed gas thereof. Examples of the oxygen-based gas include O 2 gas, O 3 gas, CO 2 gas, NO 2 gas, SO 2 gas, H 2 O gas, or a mixed gas thereof. Examples of the halogen gas include chlorine gas and fluorine gas. The chlorine-based gas is, for example, Cl 2 gas, SiCl 4 gas, CHCl 3 gas, CCl 4 gas, BCl 3 gas, or a mixed gas thereof. The fluorine-based gas is, for example, CF 4 gas, CHF 3 gas, SF 6 gas, BF 3 gas, XeF 2 gas, or a mixed gas thereof. Among these, a mixed gas of an oxygen-based gas and a halogen-based gas, particularly a mixed gas of an oxygen-based gas and a chlorine-based gas, is preferred. The mixed gas of oxygen-based gas and halogen-based gas is capable of etching the Os-based material containing Os as a main component according to this embodiment at a high etching rate.
　保護膜１２のエッチング速度ＥＲ１に対する、位相シフト膜１３のエッチング速度ＥＲ２の比（ＥＲ２／ＥＲ１）を、選択比（ＥＲ２／ＥＲ１）とも呼ぶ。選択比（ＥＲ２／ＥＲ１）が大きいほど、位相シフト膜１３の加工性が良い。選択比（ＥＲ２／ＥＲ１）は、好ましくは５．０以上であり、より好ましくは１０以上であり、さらに好ましくは３０以上である。選択比（ＥＲ２／ＥＲ１）は、好ましくは２００以下であり、より好ましくは１００以下である。 The ratio (ER2/ER1) of the etching rate ER2 of the phase shift film 13 to the etching rate ER1 of the protective film 12 is also referred to as the selectivity ratio (ER2/ER1). The larger the selectivity ratio (ER2/ER1) is, the better the processability of the phase shift film 13 is. The selectivity ratio (ER2/ER1) is preferably 5.0 or more, more preferably 10 or more, and still more preferably 30 or more. The selectivity ratio (ER2/ER1) is preferably 200 or less, more preferably 100 or less.
　位相シフト膜１３は、Ｏｓのみを含有していてもよいし、Ｏｓに加えて金属元素、非金属元素、又はその両方を含有していてもよい。位相シフト膜１３が、Ｏｓに加えて含有する追加的な元素は、Ｔａ、Ｃｒ、Ｍｏ、Ｗ、Ｒｅ、Ｓｉ、Ｈｆ、Ｒｕ、Ｏ、Ｂ、Ｃ、及びＮからなる群から選択される少なくとも１つであると好ましい。このような追加的な元素の位相シフト膜１３中の含有量は、１原子％～４９原子％である。 The phase shift film 13 may contain only Os, or may contain a metal element, a nonmetal element, or both in addition to Os. The additional element that the phase shift film 13 contains in addition to Os is at least one selected from the group consisting of Ta, Cr, Mo, W, Re, Si, Hf, Ru, O, B, C, and N. It is preferable that there is one. The content of such additional elements in the phase shift film 13 is 1 atomic % to 49 atomic %.
　反射型マスクの製造工程においては、開口パターン１３ａ（図２及び図３）が形成された後に、レジスト膜及びエッチングマスク膜の除去（後述のＳ２０４（図６））のために硫酸－過酸化水素水混合液（ＳＰＭ洗浄液）等を用いて洗浄が行われる。このようなＳＰＭ洗浄液に対する耐性は、位相シフト膜１３が、Ｔａ、Ｓｉ、及びＲｕからなる群から選択される少なくとも１つの元素を含有することで向上する。位相シフト膜１３が、Ｔａ、Ｓｉ、及びＲｕからなる群から選択される少なくとも１つの元素を含有する場合、その含有量は、１原子％～４９原子％が好ましく、５原子％～４５原子％であるとより好ましく、５原子％～４０原子％がさらに好ましく、５原子％～３５原子％が特に好ましく、５原子％～３０原子％が最も好ましい。 In the reflective mask manufacturing process, after the opening pattern 13a (FIGS. 2 and 3) is formed, sulfuric acid-hydrogen peroxide is used to remove the resist film and the etching mask film (S204 (FIG. 6) described later). Cleaning is performed using a mixed water solution (SPM cleaning solution) or the like. Such resistance to the SPM cleaning solution is improved by the phase shift film 13 containing at least one element selected from the group consisting of Ta, Si, and Ru. When the phase shift film 13 contains at least one element selected from the group consisting of Ta, Si, and Ru, the content is preferably 1 atomic % to 49 atomic %, and 5 atomic % to 45 atomic %. It is more preferably 5 at % to 40 at %, particularly preferably 5 at % to 35 at %, and most preferably 5 at % to 30 at %.
　また、位相シフト膜１３が、Ｃｒ、Ｗ、Ｒｅ、及びＲｕからなる群から選択される少なくとも１つの元素を含有することで、位相シフト膜１３の加工性の低下を抑制しつつ、光学特性（少なくとも屈折率ｎ及び／又は消衰係数ｋ）の調整が可能となり、上述のようなパターン転写の際のコントラストの向上に寄与できる。位相シフト膜１３が、Ｃｒ、Ｗ、Ｒｅ、及びＲｕからなる群から選択される少なくとも１つの元素を含有する場合、その含有量は、１原子％～４９原子％が好ましく、５原子％～４５原子％であるとより好ましく、５原子％～４０原子％がさらに好ましく、５原子％～３０原子％が特に好ましい。 In addition, since the phase shift film 13 contains at least one element selected from the group consisting of Cr, W, Re, and Ru, the optical properties ( At least the refractive index (n) and/or the extinction coefficient (k) can be adjusted, which can contribute to improving the contrast during pattern transfer as described above. When the phase shift film 13 contains at least one element selected from the group consisting of Cr, W, Re, and Ru, the content is preferably 1 atomic % to 49 atomic %, and 5 atomic % to 45 atomic %. It is more preferably atomic %, further preferably 5 atomic % to 40 atomic %, particularly preferably 5 atomic % to 30 atomic %.
　さらに、位相シフト膜１３が、Ｏ、Ｂ、Ｃ、及びＮからなる群から選択される少なくとも１つの元素を含有することで、光学特性の低下を抑制しつつ、結晶化を抑制でき、開口パターン１３ａの側壁のラフネスを小さくできる。位相シフト膜１３が、Ｏ、Ｂ、Ｃ、及びＮからなる群から選択される少なくとも１つの元素を含有する場合、その含有量は、１原子％～２０原子％であると好ましく、２原子％～１５原子％であるとより好ましく、３原子％～１０原子％であるとさらに好ましい。 Furthermore, since the phase shift film 13 contains at least one element selected from the group consisting of O, B, C, and N, crystallization can be suppressed while suppressing deterioration of optical properties, and the opening pattern The roughness of the side wall of 13a can be reduced. When the phase shift film 13 contains at least one element selected from the group consisting of O, B, C, and N, the content is preferably 1 atomic % to 20 atomic %, and preferably 2 atomic %. It is more preferable that the content is between 15 at % and 3 at % and even more preferably 10 at %.
　上述のようにＯｓに追加的に元素を含有させる場合であっても、位相シフト膜１３の屈折率ｎは、好ましくは０．９４０以下、より好ましくは０．９３０以下、さらに好ましくは０．９２０以下、特に好ましくは０．９１０以下である。位相シフト膜１３の屈折率ｎが小さいほど、位相シフト膜１３を薄化できる。なお、位相シフト膜１３の屈折率ｎは、好ましくは０．８８５以上である。本明細書において、屈折率ｎは、ＥＵＶ光（例えば波長１３．５ｎｍの光）に対する屈折率である。 Even in the case where Os additionally contains an element as described above, the refractive index n of the phase shift film 13 is preferably 0.940 or less, more preferably 0.930 or less, and even more preferably 0.920. It is particularly preferably 0.910 or less. The smaller the refractive index n of the phase shift film 13, the thinner the phase shift film 13 can be. Note that the refractive index n of the phase shift film 13 is preferably 0.885 or more. In this specification, the refractive index n is the refractive index for EUV light (for example, light with a wavelength of 13.5 nm).
　また、位相シフト膜１３の消衰係数ｋは、好ましくは０．０２５以上であり、より好ましくは０．０３０以上であり、さらに好ましくは０．０３２以上であり、特に好ましくは０．０３５以上である。位相シフト膜１３の消衰係数ｋが大きいほど、薄い膜厚で所望の反射率を得ることが容易になる。なお、位相シフト膜１３の消衰係数ｋは、好ましくは０．０５５以下である。本明細書において、消衰係数ｋは、ＥＵＶ光（例えば波長１３．５ｎｍの光）に対する消衰係数である。 Further, the extinction coefficient k of the phase shift film 13 is preferably 0.025 or more, more preferably 0.030 or more, still more preferably 0.032 or more, and particularly preferably 0.035 or more. be. The larger the extinction coefficient k of the phase shift film 13, the easier it becomes to obtain a desired reflectance with a thin film thickness. Note that the extinction coefficient k of the phase shift film 13 is preferably 0.055 or less. In this specification, the extinction coefficient k is an extinction coefficient for EUV light (for example, light with a wavelength of 13.5 nm).
　なお、位相シフト膜１３等の膜の屈折率ｎ及び消衰係数ｋは、Ｃｅｎｔｅｒ　ｆｏｒ　Ｘ－Ｒａｙ　Ｏｐｔｉｃｓ，Ｌａｗｒｅｎｃｅ　Ｂｅｒｋｅｌｅｙ　Ｎａｔｉｏｎａｌ　Ｌａｂｏｒａｔｏｒｙのデータベースの値、又は下記の反射率の「入射角の依存性」から算出した値とすることができる。ＥＵＶ光の入射角θと、ＥＵＶ光に対する反射率Ｒと、膜の屈折率ｎと、膜の消衰係数ｋとは、下記の式（１）を満たす。
Ｒ＝｜（ｓｉｎθ－（（ｎ＋ｉｋ）２－ｃｏｓ２θ）１／２）／（ｓｉｎθ＋（（ｎ＋ｉｋ）２－ｃｏｓ２θ）１／２）｜・・・（１）
入射角θと反射率Ｒの組み合わせを複数測定し、複数の測定データと式（１）との誤差が最小になるように、最小二乗法で屈折率ｎと消衰係数ｋを算出できる。 Note that the refractive index n and extinction coefficient k of films such as the phase shift film 13 are obtained from values in the database of Center for X-Ray Optics, Lawrence Berkeley National Laboratory, or from the "incidence angle dependence" of reflectance below. It can be a calculated value. The incident angle θ of the EUV light, the reflectance R for the EUV light, the refractive index n of the film, and the extinction coefficient k of the film satisfy the following formula (1).
R=|(sinθ-((n+ik)2-cos2θ)1/2)/(sinθ+((n+ik)2-cos2θ)1/2)|...(1)
By measuring a plurality of combinations of the incident angle θ and the reflectance R, the refractive index n and the extinction coefficient k can be calculated by the least squares method so that the error between the plurality of measurement data and equation (1) is minimized.
　位相シフト膜１３の成膜方法は、例えば、ＤＣスパッタリング法、マグネトロンスパッタリング法、イオンビームスパッタリング法、又はプラズマＣＶＤ法等である。位相シフト膜１３がＯを追加的に含有する場合には、スパッタガス中のＯ２ガスの含有量によって、位相シフト膜１３の酸素含有量を制御できる。また、位相シフト膜１３がＮを追加的に含有する場合には、スパッタガス中のＮ２ガスの含有量で、位相シフト膜１３の窒素含有量を制御できる。 The method for forming the phase shift film 13 is, for example, a DC sputtering method, a magnetron sputtering method, an ion beam sputtering method, a plasma CVD method, or the like. When the phase shift film 13 additionally contains O, the oxygen content of the phase shift film 13 can be controlled by the content of O 2 gas in the sputtering gas. Furthermore, when the phase shift film 13 additionally contains N, the nitrogen content of the phase shift film 13 can be controlled by the content of N 2 gas in the sputtering gas.
　ＤＣスパッタリング法を用いてオスミウム膜を形成する場合、成膜条件の一例は下記の通りである。
＜Ｏｓ膜の成膜条件＞
ターゲット：Ｏｓ
スパッタガス：Ａｒ
ガス圧：０．２Ｐａ
ターゲットの出力密度：１．０Ｗ／ｃｍ２～７．０Ｗ／ｃｍ２
成膜速度：０．０２０ｎｍ／ｓｅｃ～０．０６０ｎｍ／ｓｅｃ
膜厚：２０ｎｍ～６０ｎｍ。 When forming an osmium film using the DC sputtering method, an example of film forming conditions is as follows.
<Os film formation conditions>
Target: Os
Sputter gas: Ar
Gas pressure: 0.2Pa
Target power density: 1.0W/cm 2 ~7.0W/cm 2
Film formation rate: 0.020nm/sec to 0.060nm/sec
Film thickness: 20nm to 60nm.
　位相シフト膜１３上にはエッチングマスク膜１４が形成されていてもよい。エッチングマスク膜１４は、位相シフト膜１３に開口パターン１３ａを形成するために用いられる。エッチングマスク膜１４の上には、不図示のレジスト膜が設けられる。反射型マスク２の製造工程では、先ずレジスト膜に第１開口パターンを形成し、次に第１開口パターンを用いてエッチングマスク膜１４に第２開口パターンを形成し、次に第２開口パターンを用いて位相シフト膜１３に第３開口パターン１３ａを形成する。第１開口パターンと第２開口パターンと第３開口パターン１３ａは、平面視（Ｚ軸方向視）で同一の寸法及び同一の形状を有する。エッチングマスク膜１４は、レジスト膜の薄膜化を可能にする。 An etching mask film 14 may be formed on the phase shift film 13. Etching mask film 14 is used to form opening pattern 13a in phase shift film 13. A resist film (not shown) is provided on the etching mask film 14. In the manufacturing process of the reflective mask 2, first a first opening pattern is formed in the resist film, then a second opening pattern is formed in the etching mask film 14 using the first opening pattern, and then a second opening pattern is formed in the etching mask film 14. A third opening pattern 13a is formed in the phase shift film 13 using the following method. The first aperture pattern, the second aperture pattern, and the third aperture pattern 13a have the same dimensions and the same shape in a plan view (as viewed in the Z-axis direction). The etching mask film 14 allows the resist film to be made thinner.
　エッチングマスク膜１４は、Ａｌ、Ｈｆ、Ｃｒ、Ｎｂ、Ｔｉ、Ｍｏ、Ｔａ及びＳｉからなる群から選択される少なくとも１つの元素を含むことが好ましい。エッチングマスク膜１４は、上記の元素に加えて、Ｏ、Ｎ及びＢからなる群から選択される少なくとも１つの元素を含んでもよい。 Preferably, the etching mask film 14 contains at least one element selected from the group consisting of Al, Hf, Cr, Nb, Ti, Mo, Ta, and Si. The etching mask film 14 may contain at least one element selected from the group consisting of O, N, and B in addition to the above elements.
　エッチングマスク膜１４の膜厚は、１ｎｍ以上３０ｎｍ以下が好ましく、２ｎｍ以上２５ｎｍ以下がより好ましく、２ｎｍ以上１０ｎｍ以下がさらに好ましい。エッチングマスク膜１４の成膜方法は、例えば、ＤＣスパッタリング法、マグネトロンスパッタリング法、又はイオンビームスパッタリング法等である。 The thickness of the etching mask film 14 is preferably 1 nm or more and 30 nm or less, more preferably 2 nm or more and 25 nm or less, and even more preferably 2 nm or more and 10 nm or less. A method for forming the etching mask film 14 is, for example, a DC sputtering method, a magnetron sputtering method, or an ion beam sputtering method.
　また、本開示の一態様は、基板と、ＥＵＶ光を反射する多層反射膜と、多層反射膜を保護する保護膜と、ＥＵＶ光の位相をシフトさせる位相シフト膜と、をこの順で有する、反射型マスクブランクの製造方法であって、基板の上に、多層反射膜と、保護膜と、位相シフト膜と、をこの順番で製膜することを含み、位相シフト膜は、Ｏｓを３５原子％以上含むＯｓ系材料からなり、ＥＵＶ光に対して屈折率ｎが０．９４０以下であり且つ消衰係数ｋが０．０２５以上である、反射型マスクブランクの製造方法であってよい。 Further, one 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. A method for manufacturing a reflective mask blank, which includes forming a multilayer reflective film, a protective film, and a phase shift film in this order on a substrate, the phase shift film containing 35 Os atoms. % or more, and has a refractive index n of 0.940 or less and an extinction coefficient k of 0.025 or more with respect to EUV light.
　図５を参照して、一実施形態に係る反射型マスクブランク１の製造方法について説明する。反射型マスクブランク１の製造方法は、例えば、図５に示すステップＳ１０１～Ｓ１０５を有する。ステップＳ１０１では、基板１０を準備する。ステップＳ１０２では、基板１０の上面１０ａに多層反射膜１１を形成する。ステップＳ１０３では、多層反射膜１１の上に保護膜１２を形成する。ステップＳ１０４では、保護膜１２の上に位相シフト膜１３を形成する。ステップＳ１０５では、位相シフト膜１３の上にエッチングマスク膜１４を形成する。 With reference to FIG. 5, a method for manufacturing a reflective mask blank 1 according to an embodiment will be described. The method for manufacturing the reflective mask blank 1 includes steps S101 to S105 shown in FIG. 5, for example. In step S101, the substrate 10 is prepared. In step S102, a multilayer reflective film 11 is formed on the upper surface 10a of the substrate 10. In step S103, a protective film 12 is formed on the multilayer reflective film 11. In step S104, the phase shift film 13 is formed on the protective film 12. In step S105, an etching mask film 14 is formed on the phase shift film 13.
　なお、反射型マスクブランク１の製造方法は、少なくとも、ステップＳ１０１～Ｓ１０４を有していればよい。反射型マスクブランク１の製造方法は、図５に図示しない機能膜を形成するステップを更に有してもよい。 Note that the method for manufacturing the reflective mask blank 1 only needs to include at least steps S101 to S104. The method for manufacturing the reflective mask blank 1 may further include a step of forming a functional film not shown in FIG.
　さらに、本開示の一態様は、反射型マスクブランクを準備し、当該反射型マスクブランクにおける位相シフト膜に開口パターンを形成することを含む、反射型マスクの製造方法であってよい。 Furthermore, one aspect of the present disclosure may be a method for manufacturing a reflective mask, which includes preparing a reflective mask blank and forming an opening pattern in a phase shift film in the reflective mask blank.
　図６を参照して、一実施形態に係る反射型マスク２の製造方法について説明する。反射型マスク２の製造方法は、図６に示すステップＳ２０１～Ｓ２０４を有する。ステップＳ２０１では、反射型マスクブランク１を準備する。ステップＳ２０２では、エッチングマスク膜１４を加工する。エッチングマスク膜１４の上には、不図示のレジスト膜が設けられる。先ずレジスト膜に第１開口パターンを形成し、次に第１開口パターンを用いてエッチングマスク膜１４に第２開口パターンを形成する。ステップＳ２０３では、第２開口パターンを用いて位相シフト膜１３に第３開口パターン１３ａを形成する。ステップＳ２０３では、エッチングガスを用いて位相シフト膜１３をエッチングする。ステップＳ２０４では、レジスト膜及びエッチングマスク膜１４を除去する。レジスト膜の除去には、例えば硫酸－過酸化水素水混合液（ＳＰＭ洗浄液）が用いられる。エッチングマスク膜１４の除去には、例えばエッチングガスが用いられる。ステップＳ２０４（エッチングマスク膜１４の除去）で用いられるエッチングガスは、ステップＳ２０３（開口パターン１３ａの形成）で用いられるエッチングガスと同種であってもよい。なお、反射型マスク２の製造方法は、少なくとも、ステップＳ２０１及びＳ２０３を有していればよい。 With reference to FIG. 6, a method for manufacturing the reflective mask 2 according to one embodiment will be described. The method for manufacturing the reflective mask 2 includes steps S201 to S204 shown in FIG. In step S201, a reflective mask blank 1 is prepared. In step S202, the etching mask film 14 is processed. A resist film (not shown) is provided on the etching mask film 14. First, a first opening pattern is formed in the resist film, and then a second opening pattern is formed in the etching mask film 14 using the first opening pattern. In step S203, a third opening pattern 13a is formed in the phase shift film 13 using the second opening pattern. In step S203, the phase shift film 13 is etched using an etching gas. In step S204, the resist film and etching mask film 14 are removed. For example, a sulfuric acid-hydrogen peroxide mixture (SPM cleaning solution) is used to remove the resist film. For example, an etching gas is used to remove the etching mask film 14. The etching gas used in step S204 (removal of etching mask film 14) may be the same type of etching gas used in step S203 (formation of opening pattern 13a). Note that the method for manufacturing the reflective mask 2 only needs to include at least steps S201 and S203.
　以下、実験データについて説明する。下記の例１が実施例であり、例２、３が比較例である。 The experimental data will be explained below. Example 1 below is an example, and Examples 2 and 3 are comparative examples.
　（例１）
　基板と多層反射膜と保護膜と位相シフト膜とを含む反射型マスクブランクを作製した。基板として、ＳｉＯ２－ＴｉＯ２系のガラス基板（外形６インチ（１５２ｍｍ）角、厚さが６．３ｍｍ）を準備した。このガラス基板は、２０℃における熱膨張係数が０．０２×１０－７／℃であり、ヤング率が６７ＧＰａであり、ポアソン比が０．１７であり、比剛性は３．０７×１０７ｍ２／ｓ２であった。基板の表面（上面）の品質保証領域は、研磨によって０．１５ｎｍ以下の二乗平均平方根粗さＲｑと、１００ｎｍ以下の平坦度と、を有していた。基板の裏面（下面）には、マグネトロンスパッタリング法を用いて厚さ１００ｎｍのＣｒ膜を成膜した。Ｃｒ膜のシート抵抗は１００Ω／□であった。 (Example 1)
A reflective mask blank including a substrate, a multilayer reflective film, a protective film, and a phase shift film was manufactured. As a substrate, a SiO 2 -TiO 2 -based glass substrate (outer size: 6 inches (152 mm) square, thickness: 6.3 mm) was prepared. This glass substrate has a thermal expansion coefficient of 0.02×10 −7 /°C at 20°C, a Young's modulus of 67 GPa, a Poisson's ratio of 0.17, and a specific stiffness of 3.07×10 7 m. 2 / s2 . The quality assurance area on the surface (upper surface) of the substrate had a root mean square roughness Rq of 0.15 nm or less and a flatness of 100 nm or less by polishing. A Cr film with a thickness of 100 nm was formed on the back surface (lower surface) of the substrate using a magnetron sputtering method. The sheet resistance of the Cr film was 100Ω/□.
　多層反射膜として、Ｍｏ／Ｓｉ多層反射膜を形成した。Ｍｏ／Ｓｉ多層反射膜は、得られた基板を平板状の静電チャックに裏面側のＣｒ膜が対向するように固定し、該基板の表面上にイオンビームスパッタリング法を用いてＳｉ層（膜厚４．５ｎｍ）の成膜とＭｏ層（膜厚２．３ｎｍ）の成膜とを４０回繰り返すことにより形成した。Ｍｏ／Ｓｉ多層反射膜の合計膜厚は２７２ｎｍ（（４．５ｎｍ＋２．３ｎｍ）×４０）であった。多層反射膜上には、保護膜としてＲｈ膜（膜厚２．５ｎｍ）を形成した。Ｒｈ膜は、ＤＣスパッタリング法を用いて形成した。 A Mo/Si multilayer reflective film was formed as the multilayer reflective film. The Mo/Si multilayer reflective film is produced by fixing the obtained substrate to a flat electrostatic chuck with the Cr film on the back side facing, and depositing a Si layer (film) on the surface of the substrate using an ion beam sputtering method. The film was formed by repeating 40 times the formation of a Mo layer (thickness: 4.5 nm) and the Mo layer (thickness: 2.3 nm). The total film thickness of the Mo/Si multilayer reflective film was 272 nm ((4.5 nm+2.3 nm)×40). A Rh film (thickness: 2.5 nm) was formed as a protective film on the multilayer reflective film. The Rh film was formed using a DC sputtering method.
　さらに、保護膜上に、位相シフト膜として、Ｏｓ膜（膜厚３５ｎｍ）を、ＤＣスパッタリング法を用いて形成した。 Furthermore, an Os film (thickness: 35 nm) was formed as a phase shift film on the protective film using a DC sputtering method.
　（例２）
　位相シフト膜として、Ｏｓ膜に代えてＩｒ膜（膜厚３５ｎｍ）を形成したこと以外は、例１と同様にして、反射型マスクブランクを作製した。 (Example 2)
A reflective mask blank was produced in the same manner as in Example 1, except that an Ir film (thickness: 35 nm) was formed in place of the Os film as the phase shift film.
　（例３）
　位相シフト膜として、Ｏｓ膜に代えてＰｄ膜（膜厚３５ｎｍ）を形成したこと以外は、例１と同様にして、反射型マスクブランクを作製した。 (Example 3)
A reflective mask blank was produced in the same manner as in Example 1, except that a Pd film (thickness: 35 nm) was formed in place of the Os film as the phase shift film.
　表１に、異なる位相シフト膜種を備えた例１～例３の反射型マスクブランクの及びその特性を示す。 Table 1 shows the reflective mask blanks of Examples 1 to 3 with different types of phase shift films and their characteristics.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　＜屈折率ｎ及び消衰係数ｋ＞
　表１に示す位相シフト膜の屈折率ｎ及び消衰係数ｋは、Ｃｅｎｔｅｒ　ｆｏｒ　Ｘ－Ｒａｙ　Ｏｐｔｉｃｓ，Ｌａｗｒｅｎｃｅ　Ｂｅｒｋｅｌｅｙ　Ｎａｔｉｏｎａｌ　Ｌａｂｏｒａｔｏｒｙのデータベースの値、又は後述の反射率の入射角の依存性から算出した値とした。 <Refractive index n and extinction coefficient k>
The refractive index n and extinction coefficient k of the phase shift film shown in Table 1 are the values in the database of the Center for X-Ray Optics, Lawrence Berkeley National Laboratory, or the values calculated from the dependence of the reflectance on the angle of incidence described below. did.
　ＥＵＶ光の入射角θと、ＥＵＶ光に対する反射率Ｒと、位相シフト膜の屈折率ｎと、位相シフト膜の消衰係数ｋとは、下記の式（１）を満たす。
Ｒ＝｜（ｓｉｎθ－（（ｎ＋ｉｋ）２－ｃｏｓ２θ）１／２）／（ｓｉｎθ＋（（ｎ＋ｉｋ）２－ｃｏｓ２θ）１／２）｜・・・（１）
入射角θと反射率Ｒの組み合わせを複数測定し、複数の測定データと式（１）との誤差が最小になるように、最小二乗法で屈折率ｎと消衰係数ｋを算出した。 The incident angle θ of EUV light, the reflectance R for EUV light, the refractive index n of the phase shift film, and the extinction coefficient k of the phase shift film 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 were measured, and the refractive index n and extinction coefficient k were calculated by the least squares method so that the error between the plurality of measurement data and equation (1) was minimized.
　＜エッチング速度＞
　エッチングガスとしてＣｌ４ガスとＯ２ガスとの混合ガスを用い、位相シフト膜をドライエッチングして、エッチング速度を測定した。エッチングには、誘導結合プラズマ（ＩＣＰ：Ｉｎｄｕｃｔｉｖｅｌｙ　Ｃｏｕｐｌｅｄ　Ｐｌａｓｍａ）エッチング装置を用いた。装置の条件は以下の通りとした。
ＩＣＰアンテナバイアス：２００Ｗ
基板バイアス：４０Ｗ
エッチング圧力：３．５Ｐａ
エッチングガス：Ｃｌ２ガスとＯ２ガスの混合ガス
Ｃｌ２ガスの流量：１０ｓｃｃｍ
Ｏ２ガスの流量：１０ｓｃｃｍ。 <Etching speed>
The phase shift film was dry etched using a mixed gas of Cl 4 gas and O 2 gas as an etching gas, and the etching rate was measured. For etching, an inductively coupled plasma (ICP) etching device was used. The conditions of the apparatus were as follows.
ICP antenna bias: 200W
Substrate bias: 40W
Etching pressure: 3.5Pa
Etching gas: Mixed gas of Cl 2 gas and O 2 gas Flow rate of Cl 2 gas: 10 sccm
O2 gas flow rate: 10 sccm.
　表１に示すように、例１～例３で使用された位相シフト膜の材料はいずれも、低い屈折率ｎ及び高い消衰係数ｋを示す材料であった。しかしながら、Ｏｓからなる位相シフト膜（例１）は、Ｉｒ又はＰｄからなる位相シフト膜（例２、例３）に比べ、高い速度でエッチングが可能であり、加工性が高いことが分かった。 As shown in Table 1, the materials of the phase shift films used in Examples 1 to 3 were all materials exhibiting a low refractive index n and a high extinction coefficient k. However, it was found that the phase shift film made of Os (Example 1) can be etched at a higher rate and has higher workability than the phase shift films made of Ir or Pd (Examples 2 and 3).
　なお、保護膜を形成せずに多層反射膜上に直接位相シフト膜を形成したこと以外は例１～例３と同様にして反射型マスクブランクをそれぞれ作製して評価したところ、例１～例３と同様に、Ｏｓ位相シフト膜が優れていたとの評価結果が得られた。また、基板としてシリコンウエハを用いたこと以外は例１～例３と同様にして反射型マスクブランクをそれぞれ作製して評価したところ、例１～例３と同様に、Ｏｓ位相シフト膜が優れていたとの評価結果が得られた。 Incidentally, reflective mask blanks were prepared and evaluated in the same manner as in Examples 1 to 3, except that the phase shift film was directly formed on the multilayer reflective film without forming a protective film. Similarly to Example 3, the evaluation results showed that the Os phase shift film was superior. In addition, reflective mask blanks were fabricated and evaluated in the same manner as in Examples 1 to 3, except that a silicon wafer was used as the substrate. As in Examples 1 to 3, the Os phase shift film was superior. The evaluation results were as follows.
　以上、本開示に係る反射型マスクブランク、反射型マスク、反射型マスクブランクの製造方法、及び反射型マスクの製造方法について説明したが、本開示は上記実施形態などに限定されない。特許請求の範囲に記載された範疇内において、各種の変更、修正、置換、付加、削除、及び組み合わせが可能である。それらについても当然に本開示の技術的範囲に属する。 Although 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, the present disclosure is not limited to the above 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.
　本出願は、２０２２年９月９日に出願された日本国特許出願２０２２－１４３９６４号に基づく優先権を主張するものであり、その全内容をここに援用する。 This application claims priority based on Japanese Patent Application No. 2022-143964 filed on September 9, 2022, and its entire content is incorporated herein.
１　　反射型マスクブランク
２　　反射型マスク
１０　基板
１１　多層反射膜
１２　保護膜
１３　位相シフト膜
１３ａ　開口パターン
１４　　エッチングマスク膜

  1 Reflective mask blank 2 Reflective mask 10 Substrate 11 Multilayer reflective film 12 Protective film 13 Phase shift film 13a Opening pattern 14 Etching mask film

Claims (11)

  1. 　基板と、ＥＵＶ光を反射する多層反射膜と、前記多層反射膜を保護する保護膜と、前記ＥＵＶ光の位相をシフトさせる位相シフト膜と、をこの順で有する、反射型マスクブランクであって、
    　前記位相シフト膜は、Ｏｓを３５原子％以上含むＯｓ系材料からなり、前記ＥＵＶ光に対して屈折率ｎが０．９４０以下であり且つ消衰係数ｋが０．０２５以上である、反射型マスクブランク。     A reflective mask blank comprising, 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 is a reflective type, which is made of an Os-based material containing 35 atomic % or more of Os, and has a refractive index n of 0.940 or less and an extinction coefficient k of 0.025 or more with respect to the EUV light. mask blank.
  2. 　前記位相シフト膜は、Ｏｓを主成分として含む、請求項１記載の反射型マスクブランク。 The reflective mask blank according to claim 1, wherein the phase shift film contains Os as a main component.
  3. 　前記Ｏｓ系材料は、Ｏｓと、Ｔａ、Ｃｒ、Ｍｏ、Ｗ、Ｒｅ、Ｓｉ、Ｈｆ、Ｒｕ、Ｏ、Ｂ、Ｃ、及びＮからなる群から選択される少なくとも１つの元素を含む、請求項１又は２に記載の反射型マスクブランク。 1 . The Os-based material contains Os and at least one element selected from the group consisting of Ta, Cr, Mo, W, Re, Si, Hf, Ru, O, B, C, and N. Or the reflective mask blank according to 2.
  4. 　前記Ｏｓ系材料は、ＯｓとＲｕを含む、請求項１又は２に記載の反射型マスクブランク。 The reflective mask blank according to claim 1 or 2, wherein the Os-based material contains Os and Ru.
  5. 　前記位相シフト膜の膜厚が、２０ｎｍ以上６０ｎｍ以下である、請求項１又は２に記載の反射型マスクブランク。 The reflective mask blank according to claim 1 or 2, wherein the phase shift film has a thickness of 20 nm or more and 60 nm or less.
  6. 　前記保護膜は、Ｒｕ、Ｒｈ及びＳｉからなる群から選択される少なくとも１つの元素を含む、請求項１又は２に記載の反射型マスクブランク。 The reflective mask blank according to claim 1 or 2, wherein the protective film contains at least one element selected from the group consisting of Ru, Rh, and Si.
  7. 　前記位相シフト膜の上にエッチングマスク膜を有し、
    　前記エッチングマスク膜は、Ａｌ、Ｈｆ、Ｃｒ、Ｎｂ、Ｔｉ、Ｍｏ、Ｔａ及びＳｉからなる群から選択される少なくとも１つの元素を含む、請求項１又は２に記載の反射型マスクブランク。     an etching mask film on the phase shift film;
    3. The reflective mask blank according to claim 1, wherein the etching mask film contains at least one element selected from the group consisting of Al, Hf, Cr, Nb, Ti, Mo, Ta, and Si.
  8. 　前記エッチングマスク膜は、Ｏ、Ｎ及びＢからなる群から選択される少なくとも１つの元素をさらに含む、請求項７に記載の反射型マスクブランク。 The reflective mask blank according to claim 7, wherein the etching mask film further contains at least one element selected from the group consisting of O, N, and B.
  9. 　請求項１又は２に記載の反射型マスクブランクを備え、前記位相シフト膜に開口パターンを含む、反射型マスク。 A reflective mask comprising the reflective mask blank according to claim 1 or 2, wherein the phase shift film includes an opening pattern.
  10. 　基板と、ＥＵＶ光を反射する多層反射膜と、前記多層反射膜を保護する保護膜と、前記ＥＵＶ光の位相をシフトさせる位相シフト膜と、をこの順で有する、反射型マスクブランクの製造方法であって、
    　前記基板の上に、前記多層反射膜と、前記保護膜と、前記位相シフト膜と、をこの順番で製膜することを含み、
    　前記位相シフト膜は、Ｏｓを３５ａｔ％以上含むＯｓ系材料からなり、前記ＥＵＶ光に対して屈折率ｎが０．９４０以下であり且つ消衰係数ｋが０．０２５以上である、反射型マスクブランクの製造方法。     A method for manufacturing a reflective mask blank comprising, 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. And,
    forming the multilayer reflective film, the protective film, and the phase shift film in this order on the substrate,
    The phase shift film is a reflective mask made of an Os-based material containing 35 at% or more of Os, and has a refractive index n of 0.940 or less and an extinction coefficient k of 0.025 or more with respect to the EUV light. How to make blanks.
  11. 　請求項１０に記載の製造方法を用いて製造した反射型マスクブランクを準備し、
    　前記位相シフト膜に開口パターン形成することを含む、反射型マスクの製造方法。

          preparing a reflective mask blank manufactured using the manufacturing method according to claim 10,
    A method for manufacturing a reflective mask, the method comprising forming an opening pattern in the phase shift film.
PCT/JP2023/032335 2022-09-09 2023-09-05 Reflective mask blank, reflective mask, reflective mask blank manufacturing method, and reflective mask manufacturing method WO2024053634A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07114173A (en) * 1993-10-15 1995-05-02 Canon Inc Reflection mask for lithography and reduction stepper
KR20170021191A (en) * 2015-08-17 2017-02-27 주식회사 에스앤에스텍 Blankmask for Extreme Ultra-Violet Lithography and Photomask using the same
JP2021071685A (en) * 2019-11-01 2021-05-06 凸版印刷株式会社 Reflective mask and production method for reflective mask
WO2022138360A1 (en) * 2020-12-25 2022-06-30 Hoya株式会社 Reflective mask blank, reflective mask, and method for manufacturing semiconductor device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07114173A (en) * 1993-10-15 1995-05-02 Canon Inc Reflection mask for lithography and reduction stepper
KR20170021191A (en) * 2015-08-17 2017-02-27 주식회사 에스앤에스텍 Blankmask for Extreme Ultra-Violet Lithography and Photomask using the same
JP2021071685A (en) * 2019-11-01 2021-05-06 凸版印刷株式会社 Reflective mask and production method for reflective mask
WO2022138360A1 (en) * 2020-12-25 2022-06-30 Hoya株式会社 Reflective mask blank, reflective mask, and method for manufacturing semiconductor device

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