WO2023054145A1 - 多層反射膜付き基板、反射型マスクブランク、反射型マスク、及び半導体装置の製造方法 - Google Patents

多層反射膜付き基板、反射型マスクブランク、反射型マスク、及び半導体装置の製造方法 Download PDF

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WO2023054145A1
WO2023054145A1 PCT/JP2022/035292 JP2022035292W WO2023054145A1 WO 2023054145 A1 WO2023054145 A1 WO 2023054145A1 JP 2022035292 W JP2022035292 W JP 2022035292W WO 2023054145 A1 WO2023054145 A1 WO 2023054145A1
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Prior art keywords
film
multilayer reflective
reflective film
substrate
refractive index
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English (en)
French (fr)
Japanese (ja)
Inventor
禎一郎 梅澤
洋平 池邊
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Hoya Corp
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Hoya Corp
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Priority to US18/692,007 priority Critical patent/US20240377719A1/en
Priority to JP2023551400A priority patent/JPWO2023054145A1/ja
Priority to KR1020247007779A priority patent/KR20240070522A/ko
Publication of WO2023054145A1 publication Critical patent/WO2023054145A1/ja
Anticipated expiration legal-status Critical
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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
    • G03F1/38—Masks having auxiliary features, e.g. special coatings or marks for alignment or testing; Preparation thereof
    • G03F1/48—Protective coatings
    • 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
    • G03F1/54—Absorbers, e.g. of opaque materials
    • 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
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/20—Exposure; Apparatus therefor
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—HANDLING OF PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
    • G21K1/06—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diffraction, refraction or reflection, e.g. monochromators

Definitions

  • the present invention relates to a substrate with a multilayer reflective film, a reflective mask blank, a reflective mask, and a method for manufacturing a semiconductor device.
  • EUV lithography which is an exposure technology using Extreme Ultra Violet (hereinafter referred to as EUV) light, has been proposed.
  • a reflective mask consists of a multilayer reflective film formed on a substrate for reflecting exposure light, and an absorber, which is a patterned absorber film formed on the multilayer reflective film for absorbing exposure light. pattern.
  • a light image reflected by the multilayer reflective film is transferred onto a semiconductor substrate (transfer target) such as a silicon wafer through a reflective optical system.
  • Patent Document 1 discloses an EUV blank mask including a substrate, a reflective film laminated on the substrate, and an absorbing film laminated on the reflective film. is described.
  • the reflective film is composed of a first layer composed of Ru or a Ru compound in which one or more elements of Mo, Nb, and Zr are added to Ru, and Si It is described as having a structure in which the pairs, including the structured second layer, are laminated multiple times.
  • Patent Document 2 describes a multilayer reflector for soft X-rays and vacuum ultraviolet rays having a multilayer thin film structure composed of alternating layers of two main materials A and B having different refractive indices.
  • Patent Document 2 discloses that at least one secondary material thin film having an effect of reducing the roughness of the lamination interface is laminated between each AB layer and/or between the BA layers to form a periodic structure.
  • the low refractive index layer is generally made of a high melting point metal material such as tungsten or molybdenum or a compound containing them as a main component, and the high refractive index layer is generally made of carbon, silicon, boron, beryllium or the like.
  • Patent Document 3 discloses a multilayer spectroscopic reflector characterized by using a compound intermediate layer composed of Si and C between a heavy element layer and a light element layer of a multilayer spectroscopic element having a Bragg diffraction effect. Are listed. Further, Patent Document 3 describes that a multilayer film was produced by using Mo, Ru, Rh, and Re as heavy element layers, using Si for light element layers, and using Si 100-x C x for intermediate layers. It is
  • Patent Document 4 describes a multilayer film X-ray reflector in which a plurality of material layers are periodically laminated. Patent Document 4 describes forming an intermediate layer between each layer of material layers, and using a material having a melting point higher than that of at least one of the material layers as the intermediate layer. Further, Patent Document 4 describes that a Mo/Si multilayer film was produced by using Mo as a heavy element layer and using Si as a light element layer.
  • Non-Patent Document 1 describes the use of B4C interlayers for Mo/Si multilayer reflectors.
  • Non-Patent Document 1 describes that a Ru/Si multilayer reflective film is used as the multilayer reflective film.
  • JP 2021-110953 A JP-A-2-242201 JP-A-5-203798 JP-A-9-230098
  • EUV lithography is an exposure technology that uses extreme ultraviolet light (EUV light).
  • EUV light is light in the wavelength band of the soft X-ray region or the vacuum ultraviolet region, specifically light with a wavelength of approximately 0.2 to 100 nm.
  • EUV light with a wavelength of 13-14 nm eg, 13.5 nm wavelength
  • EUV light with a wavelength of 13-14 nm eg, 13.5 nm wavelength
  • a reflective mask with an absorber pattern is used for EUV lithography.
  • the EUV light irradiated to the reflective mask is absorbed in the portion where the absorber pattern exists and is reflected in the portion where the absorber pattern does not exist.
  • the multilayer reflective film is exposed in a portion where the absorber pattern does not exist.
  • the exposed multilayer reflective film reflects EUV light.
  • EUV lithography a light image reflected by a multilayer reflective film (a portion where an absorber pattern does not exist) is transferred onto a semiconductor substrate (transfer target) such as a silicon wafer through a reflective optical system.
  • a multilayer reflective film a multilayer film in which elements with different refractive indices are stacked periodically is generally used.
  • a multilayer reflective film for EUV light with a wavelength of 13 to 14 nm for example, a wavelength of 13.5 nm
  • Mo/ A Si periodic laminated film is used as a multilayer reflective film for EUV light with a wavelength of 13 to 14 nm (for example, a wavelength of 13.5 nm).
  • the reflective area (surface of the multilayer reflective film) in the reflective mask must have a high reflectance for EUV light, which is the exposure light. It is necessary to have
  • the effective reflection surface relatively close to the surface of the multilayer reflection film may be referred to as "shallow effective reflection surface". Since the multilayer reflective film has a shallow effective reflective surface, the 3D effect can be suppressed and the number of laminations of the multilayer reflective film can be reduced.
  • the multilayer reflective film reflects EUV light due to its laminated structure of a low refractive index layer and a high refractive index layer.
  • the material of the multilayer reflective film is selected so as to increase the reflectance of EUV light, depending on the material, a phenomenon occurs in which the material atoms diffuse between the low-refractive-index layer and the high-refractive-index layer. There is When such a diffusion phenomenon occurs, the reflectance of the multilayer reflective film decreases.
  • the present invention provides a multi-layer reflective film having a shallow effective reflective surface and a multi-layer reflective film capable of suppressing the diffusion of material atoms between a low refractive index layer and a high refractive index layer.
  • An object of the present invention is to provide a film-coated substrate, a reflective mask blank, and a reflective mask.
  • Another object of the present invention is to provide a method of manufacturing a semiconductor device using the reflective mask.
  • the present invention has the following configuration.
  • Configuration 1 of the present invention is a substrate with a multilayer reflective film having a substrate and a multilayer reflective film provided on the substrate,
  • the multilayer reflective film includes a multilayer film in which low refractive index layers and high refractive index layers containing silicon (Si) are alternately laminated, the multilayer reflective film further comprising at least one intermediate layer disposed between the low refractive index layer and the high refractive index layer;
  • the multilayer reflective film contains at least one additive element selected from nitrogen (N), carbon (C) and oxygen (O),
  • a substrate with a multilayer reflective film is characterized in that the content of the additive element in the multilayer reflective film is 40 atomic % or less.
  • Structure 2 of the present invention is the substrate with a multilayer reflective film according to Structure 1, wherein the content of the additive element is 1 atomic % or more.
  • composition 3 of the present invention is the substrate with a multilayer reflective film according to Configuration 1 or 2, wherein the intermediate layer contains at least one selected from SiN, SiO, SiC, SiON, SiCN, SiOC and SiOCN. be.
  • Structure 4 of the present invention is the substrate with a multilayer reflective film according to any one of Structures 1 to 3, wherein the low refractive index layer contains ruthenium (Ru).
  • the low refractive index layer contains ruthenium (Ru),
  • Structure 6 of the present invention is the substrate with a multilayer reflective film according to any one of claims 1 to 5, further comprising a protective film on the multilayer reflective film.
  • Configuration 7 of the present invention is a SiN material layer containing silicon (Si) and nitrogen (N) or a SiC material layer containing silicon (Si) and carbon (C) on the side where the protective film is in contact with the multilayer reflective film.
  • Structure 8 of the present invention is a reflective mask blank characterized by having an absorber film on the protective film of the substrate with a multilayer reflective film of Structure 6 or 7.
  • Structure 9 of the present invention is a reflective mask blank characterized by comprising an absorber film on the multilayer reflective film of the substrate with a multilayer reflective film according to any one of Structures 1 to 5.
  • Structure 10 of the present invention is a reflective mask characterized by having an absorber pattern obtained by patterning the absorber film of the reflective mask blank of Structure 8 or 9.
  • Structure 11 of the present invention is a method of manufacturing a semiconductor device, comprising a step of performing a lithography process using an exposure apparatus using the reflective mask of Structure 10 to form a transfer pattern on a transfer target. be.
  • the multilayer reflector has a shallow effective reflection surface and a multilayer reflection film capable of suppressing the diffusion of material atoms between the low refractive index layer and the high refractive index layer. Substrates with films, reflective mask blanks, and reflective masks can be provided. Further, according to the present invention, it is possible to provide a method of manufacturing a semiconductor device using the reflective mask.
  • FIG. 3 is a schematic cross-sectional view showing another example of the substrate with a multilayer reflective film according to the present embodiment; It is a cross-sectional schematic diagram which shows an example of the reflective mask blank of this embodiment.
  • FIG. 4 is a schematic cross-sectional view showing another example of the reflective mask blank of the present embodiment;
  • FIG. 5 is a schematic cross-sectional view showing still another example of the reflective mask blank of the present embodiment; It is a cross-sectional schematic diagram which shows an example of the manufacturing method of the reflective mask of this embodiment.
  • FIG. 1 is a schematic cross-sectional view showing Embodiment 1 of a multilayer reflective film of a substrate with a multilayer reflective film of the present embodiment.
  • FIG. FIG. 2 is a schematic cross-sectional view showing Embodiment 2 of the multilayer reflective film of the substrate with the multilayer reflective film of the present embodiment.
  • FIG. 3 is a schematic cross-sectional view showing Embodiment 3 of the multilayer reflective film of the substrate with the multilayer reflective film of the present embodiment.
  • FIG. 5 is a schematic cross-sectional view showing Embodiment 4 of the multilayer reflective film of the substrate with the multilayer reflective film of the present embodiment.
  • FIG. 5 is a schematic cross-sectional view showing Embodiment 5 of the multilayer reflective film of the substrate with the multilayer reflective film of the present embodiment.
  • FIG. 6 is a schematic cross-sectional view showing Embodiment 6 of the multilayer reflective film of the substrate with the multilayer reflective film of the present embodiment. It is a schematic diagram which shows an example of an EUV exposure apparatus.
  • FIG. 1 is a schematic cross-sectional view showing an example of a substrate 90 with a multilayer reflective film according to this embodiment.
  • a substrate 90 with a multilayer reflective film of this embodiment includes a substrate 1 and a multilayer reflective film 2 provided on the substrate 1 .
  • the multilayer reflective film 2 includes a multilayer film in which low refractive index layers 24 and high refractive index layers 22 are alternately laminated.
  • the multilayer reflective film 2 further comprises at least one intermediate layer 26 arranged between the low refractive index layer 24 and the high refractive index layer 22 .
  • a back surface conductive film 5 for an electrostatic chuck may be formed on the back surface of the substrate 1 (the surface opposite to the side on which the multilayer reflective film 2 is formed).
  • FIG. 2 is a schematic cross-sectional view showing another example of the substrate 90 with a multilayer reflective film according to this embodiment.
  • a substrate 90 with a multilayer reflective film shown in FIG. 2 includes a substrate 1 , a multilayer reflective film 2 formed on the substrate 1 , and a protective film 3 formed on the multilayer reflective film 2 .
  • the multilayer reflective film 2 includes a low refractive index layer 24, a high refractive index layer 22, and at least one intermediate layer disposed between the low refractive index layer 24 and the high refractive index layer 22. It has layer 26 .
  • a back surface conductive film 5 for an electrostatic chuck may be formed on the back surface of the substrate 1 (the surface opposite to the side on which the multilayer reflective film 2 is formed).
  • the phrase “place (form) thin film B on thin film A (or substrate)” means that thin film B is placed (formed) in contact with the surface of thin film A (or substrate). In addition to the case of meaning, it also includes the case of having another thin film C between the thin film A (or substrate) and the thin film B. Further, in this specification, for example, the phrase “the thin film B is arranged in contact with the surface of the thin film A (or the substrate)” means that the thin film A (or the substrate) and the thin film B are disposed without another thin film interposed therebetween. , means that the thin film A (or substrate) and the thin film B are arranged so as to be in direct contact with each other. In addition, in this specification, “above” does not necessarily mean the upper side in the vertical direction. "On” merely indicates the relative positional relationship between the thin film and the substrate 1 and the like.
  • the substrate 90 with a multilayer reflective film according to this embodiment will be specifically described.
  • the substrate 1 preferably has a low coefficient of thermal expansion within the range of 0 ⁇ 5 ppb/° C. in order to prevent distortion of the transfer pattern due to heat during exposure to EUV light.
  • a material having a low coefficient of thermal expansion within this range for example, SiO 2 —TiO 2 -based glass, multicomponent glass-ceramics, or the like can be used.
  • the main surface (first main surface) of the substrate 1 on which the transfer pattern (absorber pattern 4a to be described later) is formed is preferably processed in order to increase the degree of flatness.
  • the flatness is preferably 0.1 ⁇ m or less, more preferably 0.05 ⁇ m or less, and particularly preferably 0.05 ⁇ m or less in a 132 mm ⁇ 132 mm area of the main surface of the substrate 1 on which the transfer pattern is formed. It is preferably 0.03 ⁇ m or less.
  • the second main surface (rear surface) opposite to the side on which the transfer pattern is formed is the surface fixed to the exposure device by an electrostatic chuck.
  • the flatness is 0.1 ⁇ m or less, more preferably 0.05 ⁇ m or less, and particularly preferably 0.03 ⁇ m or less.
  • the flatness is a value representing the warp (amount of deformation) of the surface indicated by TIR (Total Indicated Reading).
  • TIR Total Indicated Reading
  • the flatness (TIR) is measured by taking the surface of the substrate 1 as a reference and defining the plane determined by the method of least squares as the focal plane, and measuring the highest position of the surface of the substrate 1 above the focal plane and the substrate below the focal plane. It is the absolute value of the height difference with the lowest position of the surface of 1.
  • the surface roughness of the main surface of the substrate 1 on which the transfer pattern is formed is preferably 0.1 nm or less in root-mean-square roughness (Rq).
  • the surface roughness can be measured with an atomic force microscope.
  • the substrate 1 preferably has high rigidity in order to prevent deformation of the thin film (such as the multilayer reflective film 2) formed thereon due to film stress.
  • the substrate 1 one having a high Young's modulus of 65 GPa or more is particularly preferable.
  • the multilayer reflective film-attached substrate 90 of this embodiment has a substrate 1 and a multilayer reflective film 2 provided on the substrate 1 .
  • the multilayer reflective film 2 has a structure in which a plurality of layers whose main components are elements with different refractive indices are stacked periodically.
  • the multilayer reflective film 2 includes a thin film of a light element or its compound (high refractive index layer 22) which is a high refractive index material, and a thin film of a heavy element or its compound (low refractive index layer 22) which is a low refractive index material. 24) and are alternately laminated.
  • the multilayer reflective film 2 of the substrate 90 with a multilayer reflective film of the present embodiment includes a multilayer film in which low refractive index layers 24 and high refractive index layers 22 containing silicon (Si) are alternately laminated.
  • the high refractive index layer 22 is a layer containing silicon (Si).
  • the high refractive index layer 22 may contain Si alone or may contain a Si compound.
  • the Si compound may contain Si and at least one element selected from the group consisting of B, C, N, O and H.
  • the high refractive index layer 22 is preferably made of silicon (Si). Note that “the high refractive index layer 22 is made of silicon (Si)” does not prevent impurities other than Si from being unavoidably mixed in the high refractive index layer 22 . The same is true for other thin films and other elements.
  • the content of silicon (Si) in the multilayer reflective film 2 of this embodiment is preferably 50 atomic % or more, more preferably 65 atomic % or more.
  • the content of silicon (Si) in the multilayer reflective film 2 is preferably 99 atomic % or less, more preferably 95 atomic % or less.
  • the content of silicon (Si) in the multilayer reflective film 2 is the total content of Si forming the high refractive index layer 22 and the intermediate layer 26 .
  • the low refractive index layer 24 is a layer containing at least one element selected from the group consisting of Mo, Ru, Rh, and Pt, or selected from the group consisting of Mo, Ru, Rh, and Pt. It can be a layer comprising an alloy comprising at least one element which is
  • the low refractive index layer 24 of the substrate 90 with a multilayer reflective film of this embodiment preferably contains ruthenium (Ru).
  • Ru ruthenium
  • Examples of the material of the low refractive index layer 24 containing Ru include simple Ru, RuRh, RuNb, and RuMo.
  • the content of the elements constituting the low refractive index layer 24 in the multilayer reflective film 2 of this embodiment is preferably 40 atomic % or more, more preferably 55 atomic % or more. Also, the content of the elements constituting the low refractive index layer 24 in the multilayer reflective film 2 is preferably 99 atomic % or less, more preferably 85 atomic % or less. When a plurality of elements forming the low refractive index layer 24 are included, the content of the elements forming the low refractive index layer 24 in the multilayer reflective film 2 is the total content of those elements.
  • the 3D effect means that the three-dimensional structure including the structure in the height direction of the reflective mask 200 affects the fidelity of the transferred pattern with respect to the mask pattern.
  • controlling the reflective surface of the reflective mask 200 is necessary to suppress the 3D effect. Specifically, it is necessary to bring the effective reflection surface of the multilayer reflection film 2 as close to the surface as possible for the control of the reflection surface. Since the reflective mask 200 has a shallow effective reflective surface, the EUV light reflected from the multilayer reflective film 2 can be controlled so as not to spread, thereby suppressing the 3D effect.
  • the multilayer reflective film 2 includes a multilayer film in which a low refractive index layer 24 containing ruthenium (Ru) and a high refractive index layer 22 containing silicon (Si) are alternately laminated, the conventional Mo/Si multilayer
  • the effective reflective surface of the multilayer reflective film 2 can be made shallower than that of the reflective film.
  • the multilayer reflective film 2 further comprises at least one predetermined intermediate layer 26 disposed between the low refractive index layer 24 and the high refractive index layer 22. can suppress the occurrence of this problem.
  • the multilayer reflective film 2 of the substrate 90 with a multilayer reflective film of this embodiment includes at least one intermediate layer 26 disposed between the low refractive index layer 24 and the high refractive index layer 22. further includes By including the intermediate layer 26 in the multilayer reflective film 2 , diffusion of Si in the high refractive index layer 22 to the low refractive index layer 24 can be suppressed.
  • the multilayer reflective film 2 contains at least one additive element selected from nitrogen (N), carbon (C) and oxygen (O). Note that these elements can be contained in the intermediate layer 26 .
  • the film thickness of the intermediate layer 26 is considerably thin.
  • the film thickness of the intermediate layer 26 is 1.2 nm or less, for example, about 0.3 nm.
  • the predetermined additive element is an element added to form the intermediate layer 26, but is present in the multilayer reflective film 2 (in the intermediate layer 26, the low refractive index layer 24, and the high refractive index layer 22). It can be said that it is an element that
  • the film thickness of the intermediate layer 26 is preferably 0.1 nm to 1.2 nm, more preferably 0.3 nm to 1.0 nm. By setting the film thickness of the intermediate layer 26 within a predetermined range, it is possible to more reliably suppress diffusion of Si in the high refractive index layer 22 into the low refractive index layer 24 .
  • the content of the additive element in the multilayer reflective film 2 of the substrate 90 with the multilayer reflective film of this embodiment is 40 atomic % or less. If the content of the additive element is too high, the reflectance of the multilayer reflective film 2 to EUV light may be adversely affected.
  • nitrogen (N) is the additive element
  • the content of the additive element (N) in the multilayer reflective film 2 is preferably 35 atomic % or less, more preferably 20 atomic % or less.
  • carbon (C) is the additive element
  • the content of the additive element (C) in the multilayer reflective film 2 is preferably 40 atomic % or less, more preferably 30 atomic % or less.
  • oxygen (O) is the additive element
  • the content of the additive element (O) in the multilayer reflective film 2 is preferably 15 atomic % or less, more preferably 10 atomic % or less.
  • the content of the additive element in the multilayer reflective film 2 of the substrate 90 with the multilayer reflective film of the present embodiment is preferably 1 atomic % or more.
  • the multilayer reflective film 2 contains the additive element (N).
  • the amount is preferably 5 atomic % or more, more preferably 10 atomic % or more.
  • carbon (C) is the additive element
  • the content of the additive element (C) in the multilayer reflective film 2 is preferably 10 atomic % or more, more preferably 20 atomic % or more.
  • oxygen (O) is the additive element
  • the content of the additive element (O) in the multilayer reflective film 2 is preferably 3 atomic % or more, more preferably 5 atomic % or more.
  • the intermediate layer 26 of the multilayer reflective film 2 of the substrate 90 with a multilayer reflective film of the present embodiment preferably contains at least one selected from SiN, SiO, SiC, SiON, SiCN, SiOC and SiOCN. Since the intermediate layer 26 is a silicon compound of these, the intermediate layer 26 disposed between the low refractive index layer 24 and the high refractive index layer 22 allows the Si of the high refractive index layer 22 to can be more reliably suppressed from diffusing into Intermediate layer 26 may also include at least one boron compound selected from B 4 C and BN. The intermediate layer 26 is preferably made of at least one selected from B4C and BN. By including a predetermined boron compound in the intermediate layer 26 , it is possible to more reliably suppress diffusion of Si in the high refractive index layer 22 to the low refractive index layer 24 .
  • the multilayer reflective film 2 In order to form the multilayer reflective film 2, it is generally possible to laminate the high refractive index layer 22 and the low refractive index layer 24 in this order from the substrate 1 side for a plurality of cycles. In this case, one (high refractive index layer 22/low refractive index layer 24) laminated structure constitutes one period.
  • the multilayer reflective film 2 includes the intermediate layer 26, so the intermediate layer 26 can be appropriately arranged between the high refractive index layer 22 and the low refractive index layer 24. .
  • Embodiment 1 of the multilayer reflective film 2 a structure in which a high refractive index layer 22, an intermediate layer 26, a low refractive index layer 24, and an intermediate layer 26 are stacked in this order from the substrate 1 side for a plurality of cycles. be able to.
  • the structure of "high refractive index layer 22/intermediate layer 26/low refractive index layer 24/intermediate layer 26" is one unit (one period).
  • FIG. 7 shows an example in which one period of the multilayer reflective film 2 of Embodiment 1 is arranged on the substrate 1 .
  • the surface layer of the uppermost period (the one period farthest from the substrate 1) is the intermediate layer 26 (Si-containing layer). .
  • Embodiment 2 of the multilayer reflective film 2 it is possible to have a structure in which the high refractive index layer 22, the intermediate layer 26 and the low refractive index layer 24 are laminated in this order from the substrate 1 side for a plurality of cycles.
  • FIG. 8 shows an example in which one period of the multilayer reflective film 2 of Embodiment 2 is arranged on the substrate 1 .
  • the structure of "high refractive index layer 22/intermediate layer 26/low refractive index layer 24" is one unit (one cycle).
  • the surface layer of one uppermost period is the low refractive index layer 24 .
  • Embodiment 3 of the multilayer reflective film 2 a structure in which the high refractive index layer 22, the low refractive index layer 24, and the intermediate layer 26 are laminated in this order from the substrate 1 side can be used.
  • FIG. 9 shows an example in which one period of the multilayer reflective film 2 of Embodiment 3 is arranged on the substrate 1 .
  • the structure of "high refractive index layer 22/low refractive index layer 24/intermediate layer 26" is one unit (one period).
  • the intermediate layer 26 Si-containing layer
  • Embodiment 4 of the multilayer reflective film 2 a structure in which the low refractive index layer 24, the intermediate layer 26, the high refractive index layer 22, and the intermediate layer 26 are stacked in this order from the substrate 1 side can be made to have a structure in which multiple periods are stacked.
  • FIG. 10 shows an example in which one period of the multilayer reflective film 2 of Embodiment 4 is arranged on the substrate 1 .
  • the structure of "low refractive index layer 24/intermediate layer 26/high refractive index layer 22/intermediate layer 26" is one unit (one cycle).
  • the intermediate layer 26 Si-containing layer
  • Embodiment 5 of the multilayer reflective film 2 it is possible to have a structure in which the low refractive index layer 24, the intermediate layer 26 and the high refractive index layer 22 are stacked in this order from the substrate 1 side for a plurality of cycles.
  • FIG. 11 shows an example in which one period of the multilayer reflective film 2 of Embodiment 5 is arranged on the substrate 1 .
  • the structure of "low refractive index layer 24/intermediate layer 26/high refractive index layer 22" is one unit (one period).
  • the topmost period of the surface layer is the high refractive index layer 22 .
  • Embodiment 6 of the multilayer reflective film 2 a structure in which the low refractive index layer 24, the high refractive index layer 22, and the intermediate layer 26 are stacked in this order from the substrate 1 side can be made to have a structure in which multiple periods are stacked.
  • FIG. 12 shows an example in which one period of the multilayer reflective film 2 of Embodiment 6 is arranged on the substrate 1 .
  • the structure of "low refractive index layer 24/high refractive index layer 22/intermediate layer 26" is one unit (one period).
  • the topmost period of the surface layer is the intermediate layer 26 (Si-containing layer).
  • Embodiment 2 of the multilayer reflective film for example, when the low refractive index layer 24 is the surface of the multilayer reflective film 2, in order to suppress changes over time, on the uppermost one period of the low refractive index layer 24 Furthermore, it is preferable to form a layer containing Si (Si-containing layer) similar to the high refractive index layer 22 .
  • the Si-containing layer can be at least part of the protective film 3 to be described later.
  • a protective film 3, which will be described later, can include a Si-containing layer.
  • the surface layer (intermediate layer 26) of one uppermost period can also be used as a Si-containing layer that is part of the protective film 3 described later.
  • the intermediate layer 26 of the surface layer is preferably SiN, SiC or SiCN.
  • the protective film 3 can be formed on the high refractive index layer 22 .
  • the material of the intermediate layer 26 and the material of the Si-containing layer can be the same. Also, the Si-containing layer may not contain oxygen.
  • the Si-containing layer is preferably a SiN material layer or a SiC material layer. More preferably, the Si-containing layer is a SiN material layer. Further, it is more preferable that the N content of the SiN material layer is higher than the N content of the intermediate layer 26 . As a result, diffusion of Si into the protective film 3, which will be described later, can be suppressed.
  • the Si-containing layer is preferably a SiN material layer or a SiC material layer. More preferably, the Si-containing layer is a SiC material layer. Moreover, it is more preferable that the C content of the SiC material layer is higher than the C content of the intermediate layer 26 . As a result, diffusion of Si into the protective film 3, which will be described later, can be suppressed.
  • the Si-containing layer is preferably a SiN material layer or a SiC material layer. As a result, diffusion of Si into the protective film 3, which will be described later, can be suppressed.
  • the material of the intermediate layer 26 and the material of the Si-containing layer can be different.
  • the Si-containing layer is preferably a SiN material layer or a SiC material layer. More preferably, the Si-containing layer is a SiN material layer. As a result, a high reflectance can be maintained while suppressing diffusion between the high refractive index layer 22 and the low refractive index layer 24 .
  • the laminated structure of the multilayer reflective film 2 is more preferably 35 cycles or less. Since the effective reflection surface of the multilayer reflective film 2 of this embodiment is shallow, an appropriate reflectance can be obtained with a smaller number of cycles than the conventional multilayer reflective film 2 . Therefore, the 3D effect can be suppressed by using the substrate 90 with a multilayer reflective film of this embodiment.
  • the laminated structure preferably has 20 or more periods, more preferably 25 or more periods.
  • the low refractive index layer 24 of the multilayer reflective film 2 preferably has a crystalline structure.
  • the film thickness of the low refractive index layer 24 is preferably 2.5 nm or more and 3.5 nm or less.
  • the top layer of the multilayer reflective film 2 can be the low refractive index layer 24 .
  • Ru has the function of protecting the multilayer reflective film 2 from dry etching and cleaning in the manufacturing process of the reflective mask 200, which will be described later.
  • the uppermost low refractive index layer 24 of the multilayer reflective film 2 can also function as the protective film 3 .
  • the single reflectance of the multilayer reflective film 2 used in this embodiment is, for example, 65% or more.
  • the upper limit of the reflectance of the multilayer reflective film 2 is, for example, 73%.
  • the thickness and period of the layers included in the multilayer reflective film 2 can be selected so as to satisfy Bragg's law.
  • the thickness of one period is preferably about 7 nm.
  • the multilayer reflective film 2 can be formed by a known method.
  • the multilayer reflective film 2 can be formed, for example, by magnetron sputtering such as ion beam sputtering, DC sputtering, and RF sputtering.
  • the magnetron sputtering method is preferable because the high refractive index layer 22, the low refractive index layer 24 and the intermediate layer 26 can be continuously formed.
  • the intermediate layer 26 can be formed by magnetron sputtering (reactive sputtering) in a predetermined gas atmosphere using a Si target. Also, the intermediate layer 26 can be formed by a magnetron sputtering method using a SiN sintered body, a SiC sintered body or a SiO sintered body as a target. When producing a SiN sintered body, a SiC sintered body or a SiO sintered body, at least one selected from magnesium (Mg), aluminum (Al), titanium (Ti), yttrium (Y) and zirconium (Zr) An oxide of one metal can be added as a sintering aid. By adding a sintering aid, a sintered body with high density can be produced. The intermediate layer 26 thus formed contains oxides of the above metals added as sintering aids.
  • the multilayer reflective film 2 can contain at least one metal oxide selected from magnesium (Mg), aluminum (Al), titanium (Ti), yttrium (Y) and zirconium (Zr).
  • the content of the metal (at least one metal selected from Mg, Al, Ti, Y and Zr) in the multilayer reflective film 2 is preferably 0.05 atomic % to 3.0 atomic %, more preferably. is 0.1 atomic % to 2.5 atomic %.
  • the multilayer reflective film 2 is a Si/SiN/Ru multilayer film using Si as the high refractive index layer 22, SiN as the intermediate layer 26, and Ru as the low refractive index layer 24, a Si target is formed by magnetron sputtering. is used to form a Si film (high refractive index layer 22) having a film thickness of about 3.9 nm on the substrate 1 in a Kr gas atmosphere.
  • a SiN film (intermediate layer 26) having a film thickness of about 0.3 nm is formed in a Kr gas and nitrogen gas atmosphere by magnetron sputtering (reactive sputtering) using a Si target.
  • a Ru film (low refractive index layer 24) having a film thickness of about 2.8 nm is formed in a Kr gas atmosphere by magnetron sputtering using a Ru target.
  • the multilayer reflective film 2 in which the Si/SiN/Ru films are stacked in 20 to 39 cycles can be formed.
  • the total thickness of the Si/SiN/Ru films in one cycle is preferably 7 nm.
  • the multilayer reflective film-coated substrate 90 of this embodiment preferably has a protective film 3 on the multilayer reflective film 2 .
  • a protective film 3 is formed on the multilayer reflective film 2 or in contact with the surface of the multilayer reflective film 2 in order to protect the multilayer reflective film 2 from dry etching and cleaning in the manufacturing process of the reflective mask 200 to be described later. be able to.
  • the protective film 3 also has a function of protecting the multilayer reflective film 2 during black defect correction of the transfer pattern (absorber pattern 4a) using an electron beam (EB).
  • EB electron beam
  • FIG. 2 shows the case where the protective film 3 is one layer.
  • the protective film 3 can have a laminated structure of two layers.
  • the protective film 3 has a laminated structure of three or more layers, the bottom layer and the top layer are made of, for example, a layer containing ruthenium (Ru), and between the bottom layer and the top layer, a metal other than Ru, Alternatively, a structure in which an alloy is interposed can be used.
  • the protective film 3 is made of, for example, a material containing Ru as its main component.
  • Materials containing Ru as a main component include simple Ru metal, Ru containing titanium (Ti), niobium (Nb), rhodium (Rh), molybdenum (Mo), zirconium (Zr), yttrium (Y), and boron (B). , Ru alloys containing at least one metal selected from lanthanum (La), cobalt (Co) and rhenium (Re), and materials further containing nitrogen therein.
  • the protective film 3 is made of, for example, a material containing rhodium (Rh) as its main component.
  • Rh Materials containing Rh as a main component include Rh metal alone, Rh containing titanium (Ti), niobium (Nb), ruthenium (Ru), molybdenum (Mo), zirconium (Zr), yttrium (Y), and boron (B). , Rh alloys containing at least one metal selected from lanthanum (La), cobalt (Co) and rhenium (Re), and materials further comprising nitrogen therein.
  • the Ru content ratio of the Ru alloy used for the protective film 3 is 50 atomic % or more and less than 100 atomic %, preferably 80 atomic % or more and less than 100 atomic %, more preferably 95 atomic % or more and less than 100 atomic %.
  • the Rh content ratio of the Rh alloy used for the protective film 3 is 50 atomic % or more and less than 100 atomic %, preferably 80 atomic % or more and less than 100 atomic %, more preferably 95 atomic % or more and less than 100 atomic %.
  • the protective film 3 has a mask cleaning resistance, an etching stopper function when the absorber film 4 is etched, and a function of preventing the multilayer reflective film 2 from changing with time while ensuring sufficient EUV light reflectance. It is possible to combine
  • the protective film 3 of the substrate 90 with a multilayer reflective film of this embodiment preferably contains the same material as the low refractive index layer 24 . Moreover, the protective film 3 of the substrate 90 with a multilayer reflective film of the present embodiment more preferably contains at least one selected from ruthenium (Ru) and rhodium (Rh).
  • the low refractive index layer 24 preferably contains ruthenium (Ru). Therefore, it is preferable that the protective film 3 also contains the same material (Ru) as the low refractive index layer 24 .
  • the protection film 3 can be expected to function as a part of the multilayer reflective film 2 by including the same material as the low refractive index layer 24 . Therefore, an improvement in the reflectance of the multilayer reflective film 2 can be expected.
  • the protective film 3 can be formed more easily. More preferably, the protective film 3 is made of a material having the same element and the same composition ratio as the low refractive index layer 24 .
  • the film thickness of the protective film 3 is not particularly limited as long as it can function as the protective film 3 .
  • the film thickness of the protective film 3 is preferably 1.0 nm to 8.0 nm, more preferably 1.5 nm to 6.0 nm.
  • a known film forming method can be adopted without particular limitation.
  • Specific examples of the method for forming the protective film 3 include ion beam sputtering, magnetron sputtering such as DC sputtering and RF sputtering, chemical vapor deposition (CVD), and vacuum deposition.
  • the protective film 3 can include a Si-containing layer and a protective layer.
  • the Si-containing layer of the protective film 3 is formed on the side in contact with the multilayer reflective film 2, and the protective layer is formed on the Si-containing layer.
  • the protective layer can be made of the same material as the protective film 3 described above, and can be a thin film having the same function as the protective film 3 .
  • the protective film 3 of the substrate 90 with a multilayer reflective film of this embodiment preferably includes a Si-containing layer on the side in contact with the multilayer reflective film 2 .
  • the Si-containing layer may be a silicon (Si) simple layer, a SiN material layer containing silicon (Si) and nitrogen (N), a SiC material layer containing silicon (Si) and carbon (C), or silicon (Si), nitrogen ( It preferably includes a SiNC layer containing N) and carbon (C).
  • SiN material layer, SiC material layer, or SiNC layer By including a predetermined Si-containing layer (SiN material layer, SiC material layer, or SiNC layer) in the protective film 3, diffusion of Si into the protective layer can be prevented. Therefore, it is possible to prevent the reflectance of the multilayer reflective film 2 with respect to the EUV light from being much lower than the calculated value.
  • the Si-containing layer of the protective film 3 can include multiple layers with different compositions.
  • the Si-containing layer can include two layers: a layer containing Si formed in contact with the multilayer reflective film 2 and a layer containing Si and an additive element formed on the layer containing Si.
  • the layer containing Si can be a layer (Si layer) consisting only of Si.
  • the layer containing Si and the additive element can be a layer consisting only of Si and the additive element.
  • the additive element is preferably nitrogen (N) and/or carbon (C). More preferably, the Si-containing layer is two layers of a Si layer and a SiN layer, SiC layer, or SiNC layer.
  • composition gradient film in which the additive element increases in the film thickness direction from the multilayer reflective film 2 side to the protective layer side may be used.
  • a SiN material layer is a layer containing silicon (Si) and nitrogen (N).
  • the SiN material layer may also contain other elements such as O, C, B and/or H.
  • SiN material layers include, for example, silicon nitride (Si x N y (x, y are integers of 1 or more)) and silicon oxynitride (Si x O y N z (x, y, z are integers of 1 or more) ).
  • the SiN material layer may include at least one material selected from, for example, SiN, Si3N4 , and SiON .
  • a SiC material layer is a layer containing silicon (Si) and carbon (C).
  • the SiC material layer may also contain other elements such as O, N, B and/or H.
  • the SiC material layer includes, for example, silicon carbide (SiC).
  • the metal (eg, Ru) contained in the protective layer and Si may combine to form metal silicide.
  • metal silicide is formed in the protective layer, there is a problem that the reflectance of the multilayer reflective film 2 for EUV light is significantly lower than the calculated value (calculated value assuming no diffusion of Si).
  • the Si-containing layer is the SiN material layer or the SiC material layer. Therefore, the existence of the Si-containing layer prevents Si from diffusing into the protective layer. can. Therefore, formation of metal silicide (eg, RuSi) in the protective layer can be prevented. As a result, it is possible to prevent the reflectance of the multilayer reflective film 2 with respect to EUV light from being much lower than the calculated value.
  • Oxygen (O 2 ) in the atmosphere may permeate the protective layer and bond with Si due to heating during annealing when manufacturing the reflective mask blank 100 , forming a layer containing SiO 2 .
  • the SiO 2 layer is formed in the protective film 3 in this manner, there is a problem that the blister resistance (H 2 resistance) of the reflective mask 200 in the exposure machine is degraded.
  • the substrate 90 with a multilayer reflective film of this embodiment it is possible to prevent the SiO 2 layer from being formed in the protective film 3 . As a result, it is possible to prevent deterioration of the blister resistance ( H2 resistance) of the reflective mask 200 in the exposure machine.
  • the content of N in the SiN material layer is preferably 5 atomic % to 35 atomic %, more preferably 10 atomic % to 20 atomic %. If the N content in the SiN material layer is less than 5 atomic percent, the effect of preventing Si from diffusing into the protective layer cannot be sufficiently obtained. When the content of N in the SiN material layer exceeds 35 atomic %, the film density of the SiN material layer becomes low, and the durability is rather deteriorated, and the reflectance is also lowered.
  • the content of C in the SiC material layer is preferably 10 atomic % to 40 atomic %, more preferably 20 atomic % to 30 atomic %. If the C content in the SiC material layer is less than 10 atomic %, the effect of preventing Si from diffusing into the protective layer cannot be sufficiently obtained. When the content of C in the SiC material layer exceeds 40 atomic %, the film density of the SiC material layer becomes low and the durability deteriorates.
  • the reflective mask blank 100 of this embodiment has an absorption layer on the multilayer reflective film 2 of the substrate 90 with the multilayer reflective film or on the protective film 3 formed in contact with the surface of the multilayer reflective film 2 .
  • a body membrane 4 is provided.
  • FIG. 3 is a schematic cross-sectional view showing an example of the reflective mask blank 100 of this embodiment.
  • a reflective mask blank 100 shown in FIG. 3 has an absorber film 4 for absorbing EUV light on the multilayer reflective film 2 of the substrate 90 with a multilayer reflective film shown in FIG. Note that the reflective mask blank 100 can further have other thin films such as the resist film 11 on the absorber film 4 .
  • the top layer of the multilayer reflective film 2 can be a low refractive index layer 24 containing Ru.
  • FIG. 4 is a schematic cross-sectional view showing an example of the reflective mask blank 100 of this embodiment.
  • a reflective mask blank 100 shown in FIG. 4 has an absorber film 4 for absorbing EUV light on the protective film 3 of the substrate 90 with a multilayer reflective film shown in FIG. Note that the reflective mask blank 100 can further have other thin films such as the resist film 11 on the absorber film 4 .
  • FIG. 5 is a schematic cross-sectional view showing another example of the reflective mask blank 100 of this embodiment.
  • the reflective mask blank 100 can have an etch mask film 6 over the absorber film 4 .
  • the reflective mask blank 100 can further have another thin film such as a resist film 11 on the etching mask film 6 .
  • the absorber film 4 can absorb EUV light.
  • EUV masks can be manufactured.
  • the reflective mask blank 100 of the present embodiment has a shallow effective reflective surface, and can suppress the phenomenon of diffusion of material atoms between the low refractive index layer 24 and the high refractive index layer 22.
  • a reflective mask blank 100 having the multilayer reflective film 2 can be obtained.
  • the basic function of the absorber film 4 is to absorb EUV light.
  • the absorber film 4 may be an absorber film 4 intended to absorb EUV light, or an absorber film 4 having a phase shift function in consideration of the phase difference of EUV light.
  • the absorber film 4 having a phase shift function absorbs EUV light and reflects part of the EUV light to shift the phase. That is, in the reflective mask 200 patterned with the absorber film 4 having a phase shift function, the portion where the absorber film 4 is formed absorbs the EUV light and reduces the light to a level that does not adversely affect the pattern transfer. to reflect some light.
  • the EUV light is reflected by the multilayer reflective film 2 (via the protective film 3 if there is one). Therefore, a desired phase difference is generated between the reflected light from the absorber film 4 having a phase shift function and the reflected light from the field portion.
  • the absorber film 4 having a phase shift function is preferably formed so that the phase difference between the reflected light from the absorber film 4 and the reflected light from the multilayer reflective film 2 is 170 degrees to 260 degrees.
  • the contrast of the projected optical image is improved by the interference of the lights with the inverted phase difference at the pattern edges. As the image contrast is improved, the resolution is increased, and various latitudes related to exposure such as exposure amount latitude and focus latitude can be increased.
  • the absorber film 4 may be a single-layer film, or may be a multilayer film composed of a plurality of films (for example, a lower-layer absorber film and an upper-layer absorber film).
  • a single-layer film the number of steps in manufacturing mask blanks can be reduced, improving production efficiency.
  • the optical constant and film thickness thereof can be appropriately set so that the upper absorber film serves as an anti-reflection film during mask pattern defect inspection using light. This improves the inspection sensitivity when inspecting mask pattern defects using light.
  • a film added with oxygen (O), nitrogen (N), etc. which improves oxidation resistance, is used as the upper absorber film, the stability over time is improved.
  • the absorber film 4 By making the absorber film 4 a multilayer film in this way, it is possible to add various functions to the absorber film 4 .
  • the absorber film 4 has a phase shift function, it is possible to widen the range of adjustment on the optical surface by making it a multilayer film, so it becomes easy to obtain a desired reflectance.
  • the material of the absorber film 4 has a function of absorbing EUV light and can be processed by etching (preferably by dry etching with chlorine (Cl)-based gas and/or fluorine (F)-based gas). and is not particularly limited as long as the material has a high etching selectivity with respect to the protective film 3 .
  • Compounds may include oxygen (O), nitrogen (N), carbon (C) and/or boron (B) in the above metals or alloys.
  • the absorber film 4 can be formed by magnetron sputtering such as DC sputtering and RF sputtering.
  • the absorber film 4 made of a tantalum compound or the like can be formed by a reactive sputtering method using a target containing tantalum and boron and using argon gas to which oxygen or nitrogen is added.
  • the crystalline state of the absorber film 4 is preferably amorphous or microcrystalline. If the surface of the absorber film 4 is not smooth or flat, the edge roughness of the absorber pattern 4a increases, and the dimensional accuracy of the pattern may deteriorate.
  • the surface roughness of the absorber film 4 is preferably 0.5 nm or less, more preferably 0.4 nm or less, still more preferably 0.3 nm or less in terms of root mean square roughness (Rms).
  • the reflective mask blank 100 of this embodiment can have an etching mask film 6 on the absorber film 4 .
  • a material of the etching mask film 6 it is preferable to use a material having a high etching selection ratio of the absorber film 4 to the etching mask film 6 (etching rate of the absorber film 4/etching rate of the etching mask film 6).
  • the etching selection ratio of the absorber film 4 to the etching mask film 6 is preferably 1.5 or more, more preferably 3 or more.
  • the reflective mask blank 100 of this embodiment preferably has an etching mask film 6 on the absorber film 4 .
  • chromium or a chromium compound examples include materials containing Cr and at least one element selected from N, O, C and H.
  • the etching mask film 6 more preferably contains CrN, CrO, CrC, CrON, CrOC, CrCN, or CrOCN, and is a CrO-based film (CrO film, CrON film, CrOC film, or CrOCN film) containing chromium and oxygen. is more preferred.
  • the material for the etching mask film 6 it is preferable to use tantalum or a tantalum compound.
  • tantalum compounds include materials containing Ta and at least one element selected from N, O, B and H. More preferably, the etching mask film 6 contains TaN, TaO, TaON, TaBN, TaBO or TaBON.
  • silicon or a silicon compound As the material for the etching mask film 6, it is preferable to use silicon or a silicon compound.
  • silicon compounds include materials containing Si and at least one element selected from N, O, C and H, metal silicon containing metals in silicon and silicon compounds (metal silicides), and metal silicon compounds (metal silicide compound) and the like.
  • metal silicon compounds include materials containing metal, Si, and at least one element selected from N, O, C and H.
  • the film thickness of the etching mask film 6 is preferably 3 nm or more in order to accurately form a pattern on the absorber film 4 . Moreover, the film thickness of the etching mask film 6 is preferably 15 nm or less in order to reduce the film thickness of the resist film 11 .
  • a back surface conductive film 5 for electrostatic chuck can be formed on the back surface of the substrate 10 (the surface opposite to the side on which the multilayer reflective film 2 is formed).
  • the sheet resistance required for the back surface conductive film 5 for electrostatic chucking is usually 100 ⁇ /square ( ⁇ /square) or less.
  • the back conductive film 5 can be formed, for example, by magnetron sputtering or ion beam sputtering using a metal such as chromium or tantalum, or an alloy target thereof.
  • the material of the back conductive film 5 is preferably a material containing chromium (Cr) or tantalum (Ta).
  • the material of the back conductive film 5 is preferably a Cr compound containing Cr and at least one selected from boron, nitrogen, oxygen, and carbon.
  • Cr compounds include CrN, CrON, CrCN, CrCON, CrBN, CrBON, CrBCN and CrBOCN.
  • the material of the back conductive film 5 is preferably Ta (tantalum), an alloy containing Ta, or a Ta compound containing at least one of boron, nitrogen, oxygen, and carbon in any of these.
  • Ta compounds include TaB, TaN, TaO, TaON, TaCON, TaBN, TaBO, TaBON, TaBCON, TaHf, TaHfO, TaHfN, TaHfON, TaHfCON, TaSi, TaSiO, TaSiN, TaSiON, and TaSiCON. can.
  • the film thickness of the back surface conductive film 5 is not particularly limited as long as it functions as a film for an electrostatic chuck.
  • the thickness of the back conductive film 5 is, for example, 10 nm to 200 nm.
  • the reflective mask 200 of this embodiment includes an absorber pattern 4a obtained by patterning the absorber film 4 of the reflective mask blank 100 described above.
  • FIG. 6A to 6D are schematic diagrams showing an example of a method for manufacturing the reflective mask 200.
  • FIG. The reflective mask blank 100 of the present embodiment described above can be used to manufacture the reflective mask 200 of the present embodiment.
  • An example of a method for manufacturing the reflective mask 200 will be described below.
  • a substrate 1, a multilayer reflective film 2 formed on the substrate 1, a protective film 3 formed on the multilayer reflective film 2, and an absorber film 4 formed on the protective film 3 are provided.
  • a reflective mask blank 100 is prepared.
  • a resist film 11 is formed on the absorber film 4 to obtain a reflective mask blank 100 with the resist film 11 (FIG. 6A).
  • a pattern is drawn on the resist film 11 by an electron beam drawing apparatus, and a resist pattern 11a is formed by developing and rinsing (FIG. 6B).
  • the absorber film 4 is dry-etched. As a result, the portion of the absorber film 4 not covered with the resist pattern 11a is etched to form an absorber pattern 4a (FIG. 6C).
  • etching gas for the absorber film 4 for example, a fluorine-based gas and/or a chlorine-based gas can be used.
  • fluorine-based gases include CF4 , CHF3 , C2F6 , C3F6 , C4F6 , C4F8 , CH2F2 , CH3F , C3F8 , SF6 , and F2 or the like can be used.
  • Cl 2 , SiCl 4 , CHCl 3 , CCl 4 , BCl 3 and the like can be used as the chlorine-based gas.
  • a mixed gas containing a fluorine-based gas and/or a chlorine-based gas and O 2 in a predetermined ratio can be used.
  • These etching gases can optionally further contain inert gases such as He and/or Ar.
  • the resist pattern 11a is removed with a resist remover.
  • the reflective mask 200 of the present embodiment can be obtained through a wet cleaning process using an acidic or alkaline aqueous solution (FIG. 6D).
  • a pattern (etching mask pattern) is formed on the etching mask film 6 using the resist pattern 11a as a mask. After that, a step of forming a pattern on the absorber film 4 using the etching mask pattern as a mask is added.
  • the reflective mask 200 thus obtained has a structure in which a multilayer reflective film 2, a protective film 3, and an absorber pattern 4a are laminated on a substrate 1.
  • the exposed area of the multilayer reflective film 2 (including the protective film 3) has the function of reflecting EUV light.
  • a region where the multilayer reflective film 2 (including the protective film 3) is covered with the absorber pattern 4a has the function of absorbing EUV light.
  • the reflective mask 200 of the present embodiment has a shallow effective reflective surface, and is a multi-layer mask that can suppress the diffusion of material atoms between the low-refractive-index layer 24 and the high-refractive-index layer 22 . It has a reflective film 2 . Therefore, by using the reflective mask 200 of this embodiment, it is possible to transfer a finer pattern to the transfer target.
  • the manufacturing method of the semiconductor device of this embodiment has a step of performing a lithography process using an exposure apparatus using the above-described reflective mask 200 to form a transfer pattern on a transfer target.
  • a transfer pattern can be formed on the semiconductor substrate 60 (transfer target) by lithography using the reflective mask 200 of the present embodiment. This transfer pattern has a shape obtained by transferring the pattern of the reflective mask 200 .
  • a semiconductor device can be manufactured by forming a transfer pattern on the semiconductor substrate 60 using the reflective mask 200 .
  • the multilayer reflective film 2 has a shallow effective reflective surface and can suppress the diffusion of material atoms between the low refractive index layer 24 and the high refractive index layer 22.
  • a semiconductor device can be manufactured using the reflective mask 200 having Therefore, by using the reflective mask 200 of this embodiment, the density and accuracy of the semiconductor device can be increased.
  • FIG. 13 shows a schematic configuration of an EUV exposure apparatus 50, which is an apparatus for transferring a transfer pattern onto a resist film formed on a semiconductor substrate 60.
  • an EUV light generator 51 an irradiation optical system 56, a reticle stage 58, a projection optical system 57, and a wafer stage 59 are precisely arranged along the optical path axis of EUV light.
  • the container of the EUV exposure apparatus 50 is filled with hydrogen gas.
  • the EUV light generation section 51 has a laser light source 52 , a tin droplet generation section 53 , a capture section 54 and a collector 55 .
  • the tin droplets emitted from the tin droplet generator 53 are irradiated with a high-power carbon dioxide laser from the laser light source 52, the tin droplets are plasmatized to generate EUV light.
  • the generated EUV light is collected by a collector 55 and made incident on a reflective mask 200 set on a reticle stage 58 via an irradiation optical system 56 .
  • the EUV light generator 51 generates EUV light with a wavelength of 13.53 nm, for example.
  • the EUV light reflected by the reflective mask 200 is normally reduced to about 1/4 of the pattern image light by the projection optical system 57 and projected onto the semiconductor substrate 60 (transferred substrate). Thereby, a given circuit pattern is transferred to the resist film on the semiconductor substrate 60 .
  • a resist pattern can be formed on the semiconductor substrate 60 by developing the exposed resist film.
  • An integrated circuit pattern can be formed on the semiconductor substrate 60 by etching the semiconductor substrate 60 using the resist pattern as a mask.
  • a semiconductor device is manufactured through these processes and other necessary processes.
  • a substrate 1 of 6025 size (approximately 152 mm ⁇ 152 mm ⁇ 6.35 mm) having polished first and second main surfaces was prepared.
  • This substrate 1 is made of low thermal expansion glass (SiO 2 —TiO 2 based glass).
  • the main surface of the substrate 1 was polished through a rough polishing process, a fine polishing process, a local polishing process, and a touch polishing process.
  • a multilayer reflective film 2 (see FIG. 8) composed of a high refractive index layer 22, an intermediate layer 26 and a low refractive index layer 24 was formed.
  • the material of the high refractive index layer 22 in Examples 1 to 8 is Si, and the material of the low refractive index layer 24 is Ru.
  • Table 1 shows the material and film thickness of the intermediate layer 26 of Examples 1-8. Further, the type of additive element added during the formation of the intermediate layer 26 and the content of the additive element in the multilayer reflective film 2 are shown in Table 1, "Content of additive element in multilayer reflective film (atomic %)". (atomic %).
  • the multilayer reflective film 2 uses a Si target and a Ru target, and forms a high refractive index layer 22 and an intermediate layer 22 on the substrate 1 by DC magnetron sputtering (reactive sputtering) in a predetermined gas atmosphere. Layers 26 and low refractive index layers 24 were formed by alternate lamination. First, in a Kr gas atmosphere, a Si target was used to form a high refractive index layer 22 made of Si so as to have the film thickness shown in Table 1 so as to be in contact with the main surface of the substrate 1 .
  • the intermediate layer 26 was formed to have the film thickness shown in Table 1.
  • Table 1 a SiN film and a SiC film were used as the intermediate layer 26 .
  • the SiN film was formed using a Si target in a mixed gas atmosphere of Kr gas and N2 gas.
  • the SiC film was formed using a SiC target in a Kr gas atmosphere.
  • a low refractive index layer 24 made of a Ru film was deposited.
  • the Ru film was formed with a film thickness of 2.8 nm using a Ru target in a Kr gas atmosphere.
  • Lamination of one high refractive index layer 22, one intermediate layer 26 and one low refractive index layer 24 constitutes one cycle (one set), and is formed by laminating 35 cycles (set) on the main surface of the substrate 1. .
  • a protective film 3 composed of a Si-containing layer and a protective layer was formed on the multilayer reflective film 2 of Examples 1-8.
  • the Si-containing layer of the protective film 3 of Examples 1 to 6 is composed of a Si film.
  • the Si film was formed with a film thickness of 3.5 nm by DC magnetron sputtering using a Si target in a Kr gas atmosphere.
  • the Si-containing layer of Example 7 consists of two layers, a Si film and a SiN film.
  • a Si film was formed on the multilayer reflective film 2 .
  • the Si film was formed with a film thickness of 3.2 nm in a Kr gas atmosphere using a Si target by a DC magnetron sputtering method.
  • a SiN film was formed.
  • the SiN film was formed in a mixed gas atmosphere of Kr gas and N 2 gas with a thickness of 0.3 nm using a Si target by a DC magnetron sputtering method (reactive sputtering method).
  • the Si-containing layer of Example 8 consists of two layers, a Si film and a SiC film.
  • a Si film was formed on the multilayer reflective film 2 .
  • the Si film was formed with a film thickness of 2.9 nm in a Kr gas atmosphere using a Si target by DC magnetron sputtering.
  • a SiC layer was deposited.
  • the SiC film was formed with a film thickness of 0.6 nm in a Kr gas atmosphere using a SiC target by a DC magnetron sputtering method.
  • a Ru film was formed as a protective layer on the Si-containing layer.
  • the Ru film was formed with a film thickness of 3.5 nm using a Ru target in a Kr gas atmosphere.
  • the substrates 90 with multilayer reflective films of Examples 1 to 8 were manufactured.
  • a substrate 90 with a multilayer reflective film of Comparative Example 1 was manufactured in the same manner as in Example 1, except that the intermediate layer 26 of the multilayer reflective film 2 was not formed.
  • the film thickness of the high refractive index layer was set to 4.2 nm
  • the film thickness of one cycle of the multilayer reflective film was set to 7 nm as in Example 1.
  • the reflectance (R1, unit %) for EUV light (wavelength 13.5 nm) of the substrates 90 with multilayer reflective films of Examples and Comparative Examples was measured.
  • a heat treatment was performed by heating the substrate 90 with the multilayer reflective film at 200° C. for 10 minutes in an air atmosphere.
  • the reflectance (R2, unit %) of the substrate 90 with the multilayer reflective film to EUV light was measured.
  • the EUV due to the heat treatment of the substrate 90 with the multilayer reflective film The change in reflectance was obtained.
  • Table 1 shows changes in EUV reflectance due to heat treatment.
  • the change in reflectance for EUV light before and after heat treatment at 200° C. for 10 minutes is 1.1% (Example 4) or less. was. Since the multilayer reflective films 2 of Examples 1 to 8 contained the predetermined intermediate layer 26, diffusion of Si from the high refractive index layer 22 to the low refractive index layer 24 was suppressed. Therefore, it is presumed that the change in reflectance was small before and after the heat treatment. In particular, the change in reflectance of Examples 2, 3, and 7, in which the material of the intermediate layer 26 was SiN, was as small as 0.1%.
  • the A reflective mask blank 100 was manufactured.
  • a back conductive film 5 made of a CrN film was formed on the second main surface (back surface) of substrate 1 of substrate 90 with a multilayer reflective film by magnetron sputtering (reactive sputtering) under the following conditions.
  • Conditions for forming the back conductive film 5 Cr target, mixed gas atmosphere of Ar and N2 (Ar: 90%, N: 10%), film thickness 20 nm.
  • the reflective mask blanks 100 of Examples 1 to 8 were manufactured.
  • Reflective mask 200 Next, using the reflective mask blanks 100 of Examples 1 to 8, reflective masks 200 were manufactured. The fabrication of the reflective mask 200 will be described with reference to FIGS. 6A through 6D.
  • a resist film 11 was formed on the absorber film 4 of the reflective mask blank 100 .
  • a desired pattern such as a circuit pattern was drawn (exposed) on the resist film 11, developed, and rinsed to form a predetermined resist pattern 11a (FIG. 6B).
  • the absorber film 4 (TaBN film) was dry-etched using Cl 2 gas to form an absorber pattern 4a (FIG. 6C). After that, the resist pattern 11a was removed (FIG. 6D).
  • the reflective masks 200 of Examples 1 to 8 were set on an EUV scanner, and EUV exposure was performed on a wafer in which a film to be processed and a resist film were formed on a semiconductor substrate 60 as a transfer target. Then, by developing the exposed resist film, a resist pattern was formed on the semiconductor substrate 56 on which the film to be processed was formed.
  • the reflective mask 200 of Examples 1 to 8 has a shallow effective reflective surface, and has a multilayer structure capable of suppressing the diffusion of material atoms between the low-refractive-index layer and the high-refractive-index layer. Since the reflective film 2 was provided, a fine and highly accurate transfer pattern (resist pattern) could be formed on the semiconductor substrate 60 (substrate to be transferred).
  • This resist pattern is transferred to the film to be processed by etching, and various processes such as the formation of insulating films and conductive films, the introduction of dopants, and annealing are performed to manufacture semiconductor devices with desired characteristics at a high yield. We were able to.

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  • Spectroscopy & Molecular Physics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Preparing Plates And Mask In Photomechanical Process (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
PCT/JP2022/035292 2021-09-30 2022-09-22 多層反射膜付き基板、反射型マスクブランク、反射型マスク、及び半導体装置の製造方法 Ceased WO2023054145A1 (ja)

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KR1020247007779A KR20240070522A (ko) 2021-09-30 2022-09-22 다층 반사막 부착 기판, 반사형 마스크 블랭크, 반사형 마스크 및 반도체 장치의 제조 방법

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2025023299A1 (ja) * 2023-07-27 2025-01-30 Hoya株式会社 多層反射膜付き基板、反射型マスクブランク、反射型マスク、及び半導体装置の製造方法
WO2025142852A1 (ja) * 2023-12-28 2025-07-03 Hoya株式会社 多層反射膜付き基板、反射型マスクブランク及び反射型マスク、並びに半導体装置の製造方法
EP4557001A3 (en) * 2023-10-30 2025-07-30 Shin-Etsu Chemical Co., Ltd. Reflective photomask blank with a multilayer reflective film with a periodic stacked structure and manufacturing method thereof
EP4664195A3 (en) * 2024-06-12 2026-01-07 Shin-Etsu Chemical Co., Ltd. Reflective photomask blank, reflective photomask and method for manufacturing reflective photomask blank

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006332153A (ja) * 2005-05-24 2006-12-07 Hoya Corp 反射型マスクブランク及び反射型マスク並びに半導体装置の製造方法
JP2016111035A (ja) * 2014-12-02 2016-06-20 エヌ・ティ・ティ・アドバンステクノロジ株式会社 多層膜反射鏡およびｅｕｖ光装置
JP2022045936A (ja) * 2020-09-10 2022-03-23 信越化学工業株式会社 Ｅｕｖマスクブランク用多層反射膜付き基板、その製造方法及びｅｕｖマスクブランク

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2723955B2 (ja) 1989-03-16 1998-03-09 キヤノン株式会社 軟ｘ線・真空紫外線用多層膜反射鏡
JP3097778B2 (ja) 1992-01-23 2000-10-10 日本電信電話株式会社 多層膜分光反射鏡
JPH09230098A (ja) 1996-02-21 1997-09-05 Nippon Telegr & Teleph Corp <Ntt> 多層膜ｘ線反射鏡
KR20210089406A (ko) 2020-01-08 2021-07-16 주식회사 에스앤에스텍 극자외선용 반사형 블랭크 마스크 및 포토마스크

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006332153A (ja) * 2005-05-24 2006-12-07 Hoya Corp 反射型マスクブランク及び反射型マスク並びに半導体装置の製造方法
JP2016111035A (ja) * 2014-12-02 2016-06-20 エヌ・ティ・ティ・アドバンステクノロジ株式会社 多層膜反射鏡およびｅｕｖ光装置
JP2022045936A (ja) * 2020-09-10 2022-03-23 信越化学工業株式会社 Ｅｕｖマスクブランク用多層反射膜付き基板、その製造方法及びｅｕｖマスクブランク

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
WOOD OBERT; WONG KEITH; PARKS VALENTIN; KEARNEY PATRICK; MEYER-ILSE JULIA; LUONG VU; PHILIPSEN VICKY; FAHEEM MOHAMMAD; LIANG YIFAN: "Improved Ru/Si multilayer reflective coatings for advanced extreme-ultraviolet lithography photomasks", PROCEEDINGS OF SPIE, vol. 9776, 18 March 2016 (2016-03-18), US , pages 977619-1 - 977619-10, XP060067570, ISBN: 978-1-5106-1533-5, DOI: 10.1117/12.2219215 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2025023299A1 (ja) * 2023-07-27 2025-01-30 Hoya株式会社 多層反射膜付き基板、反射型マスクブランク、反射型マスク、及び半導体装置の製造方法
EP4557001A3 (en) * 2023-10-30 2025-07-30 Shin-Etsu Chemical Co., Ltd. Reflective photomask blank with a multilayer reflective film with a periodic stacked structure and manufacturing method thereof
WO2025142852A1 (ja) * 2023-12-28 2025-07-03 Hoya株式会社 多層反射膜付き基板、反射型マスクブランク及び反射型マスク、並びに半導体装置の製造方法
EP4664195A3 (en) * 2024-06-12 2026-01-07 Shin-Etsu Chemical Co., Ltd. Reflective photomask blank, reflective photomask and method for manufacturing reflective photomask blank

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