WO2025115438A1 - 反射型マスクブランク、反射型マスク、反射型マスクの製造方法 - Google Patents

反射型マスクブランク、反射型マスク、反射型マスクの製造方法 Download PDF

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WO2025115438A1
WO2025115438A1 PCT/JP2024/036843 JP2024036843W WO2025115438A1 WO 2025115438 A1 WO2025115438 A1 WO 2025115438A1 JP 2024036843 W JP2024036843 W JP 2024036843W WO 2025115438 A1 WO2025115438 A1 WO 2025115438A1
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Prior art keywords
phase shift
film
shift film
reflective mask
mask blank
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English (en)
French (fr)
Japanese (ja)
Inventor
良輔 清
新吾 浦田
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AGC Inc
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Asahi Glass Co Ltd
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Publication of WO2025115438A1 publication Critical patent/WO2025115438A1/ja
Priority to JP2025188923A priority patent/JP2026012442A/ja
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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

Definitions

  • the present invention relates to a reflective mask used in EUV (Etreme Ultra Violet) exposure, which is used in the exposure process of semiconductor manufacturing, a method for manufacturing the same, and a reflective mask blank, which is the original plate for the reflective mask.
  • EUV EUV
  • EUV lithography which uses EUV light with a central wavelength of around 13.5 nm as a light source, has been considered in order to further miniaturize semiconductor devices.
  • a reflective mask has a multilayer reflective film that reflects EUV light formed on a substrate, and an absorber film that absorbs EUV light is patterned on the multilayer reflective film.
  • the EUV light incident on the reflective mask from the illumination optical system of the exposure tool is reflected by the areas without the absorber film (openings) and absorbed by the areas with the absorber film (non-openings).
  • the absorber film may be a phase shift film that shifts the phase of the EUV light to reduce the reflectance of the EUV light.
  • the phase shift film reduces the reflectance of the EUV light by causing interference between the EUV light reflected by the surface of the absorber film opposite to the multilayer reflector film side and the EUV light reflected by the surface of the absorber film on the multilayer reflector film side.
  • Patent Document 1 discloses a phase shift film containing platinum (Pt). More specifically, an absorber film (phase shift film) made of Pt is disclosed.
  • phase shift film for a reflective mask blank in addition to the optical properties of the constituent materials, low crystallinity is required to suppress variations in line width during patterning.
  • the present invention has been made in view of the above problems, and an object of the present invention is to provide a reflective mask blank that contains Pt and has low crystallinity. Another object of the present invention is to provide a reflective mask and a method for manufacturing the reflective mask.
  • the phase shift film is made of Pt and and one or more first elements X1 selected from the group consisting of Cr, Hf, Ta, and W; the content of the first element X1 in the phase shift film is 10.0 atomic % or more and less than 70.0 atomic % with respect to all atoms in the phase shift film; A reflective mask blank, wherein when the phase shift film is analyzed by X-ray photoelectron spectroscopy, the chemical shift of a peak corresponding to the 4f 7/2 orbital of Pt is 0.3 eV or more.
  • the first element X1 includes at least Ta, The reflective mask blank according to [1] or [2], wherein the content of Ta in the phase shift film is 10.0 atomic % or more and less than 70.0 atomic % with respect to all atoms in the phase shift film.
  • the first element X1 contains at least W, The reflective mask blank according to [1] or [2], wherein the content of W in the phase shift film is 10.0 to 40.0 atomic % based on all atoms in the phase shift film.
  • the first element X1 contains at least Hf
  • the semiconductor device further includes an etching mask film different from the phase shift film on the opposite side of the phase shift film from the substrate side, The reflective mask blank according to any one of [1] to [10], wherein the etching mask film contains one or more elements selected from the group consisting of Al, Si, Ti, Cr, Y, Nb, Mo, Ta, and Hf.
  • the present invention it is possible to provide a reflective mask blank which contains Pt and has low crystallinity.
  • the present invention also provides a reflective mask and a method for manufacturing a reflective mask.
  • FIG. 1 is a schematic diagram showing an example of an embodiment of a reflective mask blank of the present invention.
  • 1A to 1C are schematic diagrams showing an example of a manufacturing process for a reflective mask using a reflective mask blank of the invention.
  • a numerical range expressed using “to” means a range that includes the numerical values before and after “to” as the lower and upper limits.
  • elements such as boron, carbon, nitrogen, oxygen, aluminum, silicon, titanium, chromium, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, tantalum, tungsten, hafnium, rhenium, iridium, and platinum may be represented by their corresponding element symbols (B, C, N, O, Al, Si, Ti, Cr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ta, W, Hf, Re, Ir, and Pt, etc.).
  • the reflective mask blank of the present invention is a reflective mask blank having, in this order, a substrate, a multilayer reflective film that reflects EUV light, a protective film, and a phase shift film that shifts the phase of EUV light.
  • the phase shift film contains Pt and one or more first elements X1 selected from the group consisting of Cr, Hf, Ta and W.
  • the content of the first element X1 in the phase shift film is 10.0 atomic % or more and less than 70.0 atomic % with respect to all atoms in the phase shift film.
  • phase shift film of the reflective mask blank of the present invention is analyzed by X-ray photoelectron spectroscopy, the chemical shift of the peak corresponding to the 4f 7/2 orbital of Pt is 0.3 eV or more.
  • the reflective mask blank of the present invention will be described with reference to the drawings.
  • Fig. 1 is a cross-sectional view showing one embodiment of a reflective mask blank of the present invention.
  • the reflective mask blank 10 shown in Fig. 1 has a substrate 12, a multilayer reflective film 14, a protective film 16, and a phase shift film 18 in this order.
  • the phase shift film 18 contains Pt and the first element X1, the content of the first element X1 being within a predetermined range, and the chemical shift of the Pt being 0.3 eV or more.
  • the reflective mask blank 10 may have an etching mask film, which will be described later, on the side of the absorber film 18 opposite the substrate 12 side.
  • phase shift film in the reflective mask blank of the present invention contains Pt and, on the other hand, contains a predetermined amount of the first element X1, which tends to result in low crystallinity.
  • the chemical shift of the peak corresponding to the 4f7 / 2 orbital of Pt is 0.3 eV or more.
  • the fact that the chemical shift of Pt is in the above range indicates that it is influenced by the first element X1, and is considered to correspond to the presence of many first elements X1 around Pt. In this case, the proportion of Pt atoms adjacent to each other is small, and as a result, it is considered that the crystallinity is further reduced.
  • the substrate of the reflective mask blank of the present invention preferably has a small thermal expansion coefficient.
  • a substrate with a small thermal expansion coefficient can suppress distortion of the phase shift film pattern due to heat during exposure to EUV light.
  • the thermal expansion coefficient of the substrate at 20°C is preferably 0 ⁇ 1.0 ⁇ 10 -7 /°C, and more preferably 0 ⁇ 0.3 ⁇ 10 -7 /°C.
  • Materials with a small thermal expansion coefficient include SiO 2 --TiO 2 type glass, but are not limited thereto.
  • Substrates such as crystallized glass in which ⁇ -quartz solid solution is precipitated, quartz glass, metallic silicon, and metal can also be used.
  • the SiO2 - TiO2 -based glass is preferably a quartz glass containing 90-95% by mass of SiO2 and 5-10% by mass of TiO2 .
  • the TiO2 content is 5-10% by mass, the linear expansion coefficient is approximately zero near room temperature, and there is almost no dimensional change near room temperature.
  • the SiO2 - TiO2 -based glass may contain trace components other than SiO2 and TiO2 .
  • the surface of the substrate on which the multilayer reflective film is laminated (hereinafter also referred to as the "first main surface") preferably has high surface smoothness.
  • the surface smoothness of the first main surface can be evaluated by surface roughness.
  • the surface roughness of the first main surface is preferably 0.15 nm or less in terms of root-mean-square roughness Rq.
  • the surface roughness can be measured by an atomic force microscope, and the surface roughness will be described as the root-mean-square roughness Rq based on JIS-B0601.
  • the first main surface is preferably surface-processed to have a predetermined flatness, in order to improve the pattern transfer accuracy and positional accuracy of a reflective mask obtained using the reflective mask blank.
  • the flatness is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less.
  • the flatness can be measured using a flatness measuring device manufactured by Fujinon Corporation.
  • the size and thickness of the substrate are appropriately determined based on the design values of the mask, etc. For example, the outer shape is 6 inches (152 mm) square, and the thickness is 0.25 inches (6.3 mm).
  • the substrate is often rectangular or square in shape.
  • the substrate preferably has high rigidity in order to prevent deformation due to film stress of films (multilayer reflective film, protective film, phase shift film, etc.) formed on the substrate.
  • the Young's modulus of the substrate is preferably 65 GPa or more.
  • the multilayer reflective film of the reflective mask blank of the present invention is not particularly limited as long as it has the desired properties as a reflective film of an EUV mask blank.
  • the multilayer reflective film preferably has a high reflectance to EUV light, and specifically, when EUV light is incident on the surface of the multilayer reflective film at an incident angle of 6°, the maximum reflectance of EUV light at a wavelength of about 13.5 nm is preferably 60% or more, more preferably 65% or more. Similarly, even when a protective film is laminated on the multilayer reflective film, the maximum reflectance of EUV light at a wavelength of about 13.5 nm is preferably 60% or more, more preferably 65% or more.
  • a multilayer reflective film can achieve a high reflectance for EUV light
  • a multilayer reflective film is usually used in which high refractive index layers that exhibit a high refractive index to EUV light and low refractive index layers that exhibit a low refractive index to EUV light are alternately stacked multiple times.
  • the multilayer reflective film may be formed by stacking a high refractive index layer and a low refractive index layer in this order from the substrate side, with one cycle being a laminate structure, and may be formed by stacking a low refractive index layer and a high refractive index layer in this order, with one cycle being a laminate structure, and may be formed by stacking a low refractive index layer and a high refractive index layer in this order, with one cycle being a laminate structure.
  • the high refractive index layer may be a layer containing Si.
  • As the material containing Si in addition to simple Si, a Si compound containing Si and one or more elements selected from the group consisting of B, C, N, and O may be used.
  • the high refractive index layer containing Si By using the high refractive index layer containing Si, a reflective mask having excellent reflectance for EUV light can be obtained.
  • the low refractive index layer a layer containing a metal selected from the group consisting of Mo, Ru, Rh, and Pt, or an alloy thereof can be used.
  • the high refractive index layer is generally made of Si, and the low refractive index layer is generally made of Mo. That is, Mo/Si multilayer reflective film is the most common.
  • the multilayer reflective film is not limited thereto, and Ru/Si multilayer reflective film, Mo/Be multilayer reflective film, Mo compound/Si compound multilayer reflective film, Si/Mo/Ru multilayer reflective film, Si/Mo/Ru/Mo multilayer reflective film, Si/Ru/Mo multilayer reflective film, and Si/Ru/Mo/Ru multilayer reflective film can also be used.
  • each layer constituting the multilayer reflective film and the number of repeat units of the layers can be appropriately selected depending on the film material used and the EUV light reflectivity required for the reflective layer.
  • a Mo/Si multilayer reflective film as an example, to create a multilayer reflective film with a maximum EUV light reflectivity of 60% or more, a Mo film with a thickness of 2.3 ⁇ 0.1 nm and a Si film with a thickness of 4.5 ⁇ 0.1 nm can be laminated so that the number of repeat units is 30 to 60.
  • the layers constituting the multilayer reflective film can be formed to the desired thickness using known film formation methods such as magnetron sputtering and ion beam sputtering.
  • ion particles are supplied from an ion source to a target of a high refractive index material and a target of a low refractive index material.
  • the multilayer reflective film is a Mo/Si multilayer reflective film
  • a Si target is used to first form a Si layer of a predetermined thickness on a substrate using ion beam sputtering.
  • a Mo layer of a predetermined thickness is formed using a Mo target. This Si layer and Mo layer constitute one cycle, and the Mo/Si multilayer reflective film is formed by stacking, for example, 30 to 60 cycles.
  • the reflective mask blank of the present invention has a protective film between the multilayer reflective film and the phase shift film.
  • the protective film is provided for the purpose of protecting the multilayer reflective film from damage caused by an etching process (usually a dry etching process) when a pattern is formed in the phase shift film by the etching process.
  • the protective film preferably contains one or more elements selected from the group consisting of Si, Y, Ru, Rh, Pd, and Al, and more preferably contains at least one element selected from the group consisting of Ru and Rh.
  • Examples of materials containing Si include Si oxides, Si nitrides, Si oxynitrides, and alloys containing Si.
  • Examples of materials containing Y include Y oxide, Y fluoride, Y oxyfluoride, and Y-containing alloys.
  • Examples of materials containing Ru include simple Ru metal and Ru alloys containing Ru and one or more metals selected from the group consisting of Si, Ti, Nb, Rh, and Zr.
  • Examples of materials containing Rh include Rh metal alone, an Rh alloy containing Rh and one or more metals selected from the group consisting of Si, Ti, Nb, Ru, Ta, and Zr, an Rh-containing nitride containing the Rh alloy and nitrogen, and an Rh-containing oxynitride containing the Rh alloy, nitrogen, and oxygen.
  • Examples of materials containing Pd include simple Pd metal and Pd alloys containing Pd and one or more metals selected from the group consisting of Si, Ti, Zr, Nb, Ru, Rh, and Ta.
  • materials that can achieve the above object include Al and nitrides containing these metals and nitrogen, and Al 2 O 3 .
  • materials capable of achieving the above object are preferably Ru metal alone, Ru alloys, Rh metal alone, or Rh alloys.
  • Ru alloy a Ru-Si alloy is preferred, and as the Rh alloy, a Rh-Si alloy is preferred.
  • the thickness of the protective film is not particularly limited as long as it can function as a protective film.
  • the thickness of the protective film is preferably 1 to 10 nm, more preferably 1.5 to 6 nm, and even more preferably 2 to 5 nm.
  • the material of the protective film is Ru metal alone, a Ru alloy, Rh metal alone, or a Rh alloy, and that the thickness of the protective film is the above-mentioned preferable thickness.
  • the protective film may be a film consisting of a single layer, or may be a multi-layer film consisting of multiple layers.
  • each layer constituting the multi-layer film is preferably made of the above-mentioned preferred materials.
  • the protective film is a multi-layer film, it is also preferable that the total thickness of the multi-layer film is within the above-mentioned preferred range of protective film thickness.
  • the protective film can be formed using known film formation methods such as magnetron sputtering and ion beam sputtering.
  • magnetron sputtering When forming a Ru film using magnetron sputtering, it is preferable to use a Ru target as the target and Ar gas as the sputtering gas.
  • phase shift film of the reflective mask blank of the present invention contains Pt and one or more first elements X1 selected from the group consisting of Cr, Hf, Ta and W.
  • the content of the first element X1 in the phase shift film is 10 atomic % or more and less than 70 atomic % with respect to all atoms in the phase shift film.
  • the phase shift film of the reflective mask blank of the present invention is analyzed by X-ray photoelectron spectroscopy, the chemical shift of the peak corresponding to the 4f 7/2 orbital of Pt is 0.3 eV or more.
  • the phase shift film will be described in detail below.
  • the content of the first element X1 in the phase shift film is 10.0 atomic % or more and less than 70.0 atomic % with respect to all atoms in the phase shift film.
  • the content of the first element X1 in the phase shift film is preferably 15.0 to 65.0 atomic %, more preferably 20.0 to 60.0 atomic %, further preferably 30.0 to 50.0 atomic %, and particularly preferably 40.0 to 50.0 atomic % with respect to all atoms in the phase shift film.
  • the content of the first element X1 in the phase shift film is obtained by analysis using X-ray photoelectron spectroscopy (XPS). A detailed analysis method will be described in detail later.
  • the first element X1 is at least one selected from the group consisting of Cr, Hf, Ta, and W, and is preferably at least one selected from the group consisting of Hf, Ta, and W.
  • the phase shift film may contain only one type of the first element X1, or may contain two or more types. When the phase shift film contains two or more types of the first element X1, the content of the first element X1 refers to the total content of each of the first elements X1.
  • the content of Ta in the phase shift film is preferably 10.0 atomic % or more and less than 70.0 atomic %, more preferably 20.0 to 60.0 atomic %, further preferably 30.0 to 50.0 atomic %, and particularly preferably 33.0 to 45.0 atomic %, based on the total atoms in the phase shift film, in order to provide better optical properties against EUV light and lower crystallinity.
  • the content of W in the phase shift film is preferably 5.0 to 60.0 atomic %, more preferably 10.0 to 40.0 atomic %, further preferably 11.0 to 20.0 atomic %, and particularly preferably 11.0 to 15.0 atomic %, based on the total atoms in the phase shift film, in order to provide better optical properties against EUV light and lower crystallinity.
  • the content of Hf in the phase shift film is preferably 5.0 atomic % or more and less than 70.0 atomic %, more preferably 10.0 to 60.0 atomic %, and further preferably 15.0 to 40.0 atomic %, based on the total atoms in the phase shift film, in order to provide better optical properties against EUV light and lower crystallinity.
  • the content of Pt in the phase shift film is preferably 30.0 atomic % or more, more preferably 40.0 atomic % or more, and more preferably 50.0 atomic % or more, based on the total atoms in the phase shift film.
  • the upper limit of the content of Pt in the phase shift film is preferably less than 90.0 atomic %, more preferably 80.0 atomic % or less, even more preferably 70.0 atomic % or less, and particularly preferably 60.0 atomic % or less, based on the total atoms in the phase shift film.
  • the Pt content in the phase shift film is obtained by analyzing using XPS, the detailed analysis method of which will be described later.
  • the chemical shift of the peak corresponding to the 4f 7/2 orbital of Pt is 0.3 eV or more.
  • the chemical shift may be 0.4 eV or more, 0.5 eV or more, or 0.7 eV or more.
  • the upper limit of the chemical shift is not particularly limited, but is often 1.5 eV or less, and more often 1.2 eV or less.
  • an analytical device "PHI 5000 VersaProbe" manufactured by ULVAC-PHI, Inc. is used.
  • the device is calibrated in accordance with JIS K 0145.
  • a measurement sample of about 1 cm square is cut out from a reflective mask blank, and the measurement sample is set in a measurement holder so that the phase shift film side becomes the measurement surface.
  • a portion of the phase shift film is removed by 5 nm from the top surface with an argon ion beam. If the phase shift film is not exposed, the above-mentioned removal is continued until the phase shift film is exposed, and then a portion of the phase shift film is removed by 5 nm from the top surface.
  • the sputtering rate during the above-mentioned removal can be measured using a separately prepared sample.
  • the removed portion is irradiated with X-rays (monochromatic AlK ⁇ rays) and analyzed with a photoelectron take-off angle (the angle between the surface of the measurement sample and the direction of the detector) of 45°.
  • X-rays monochromatic AlK ⁇ rays
  • a photoelectron take-off angle the angle between the surface of the measurement sample and the direction of the detector
  • a neutralizing gun is used to suppress charge-up.
  • the analysis is performed by performing a wide scan in the binding energy range of 1,000 to 0 eV to confirm the elements present, and then performing a narrow scan according to the elements present (e.g., Pt and the first element X1).
  • the narrow scan is performed, for example, with a pass energy of 58.7 eV, an energy step of 0.1 eV, a time/step of 50 ms, and 10 accumulations.
  • the wide scan is performed with a pass energy of 58.7 eV, an energy step of 1 eV, a time/step of 50 ms, and 2 accumulations.
  • the bond energy is calibrated using the peak of the C1s orbital derived from carbon present on the measurement sample.
  • the bond energy value indicating the peak of the C1s orbital in the measurement sample is obtained from the narrow scan analysis result, and the value obtained by subtracting the bond energy value from 284.8 eV is used as the shift value.
  • the above shift value is added to the bond energy value indicating the peak of each orbital of each element obtained from the narrow scan analysis result to calculate each peak bond energy value.
  • the chemical shift of each peak refers to the deviation from the value of each peak in the literature value.
  • the value of the peak corresponding to the 4f 7/2 orbital of Pt is 71.1 eV.
  • the chemical shift is described as a shift to the high bond energy side as a positive value, and a shift to the low bond energy side as a negative value.
  • the binding energy is calibrated using Au whose surface has been cleaned in ultra-high vacuum.
  • the shift value is the value obtained by subtracting the binding energy value of the Au4f7 /2 orbital from 83.96 eV, which is obtained from the narrow scan analysis result.
  • the value indicating the peak top is read as the binding energy value.
  • the content of Pt and the first element X1 is analyzed using the relative sensitivity coefficients specific to each element and each orbital from the spectrum obtained by narrow scanning when XPS analysis is performed using the procedure described above.
  • the absolute value of the chemical shift of the first element X1 is preferably 0.1 eV or more, more preferably 0.2 eV or more, and more preferably 0.3 eV or more.
  • the chemical shift may be 0.5 eV or more, 0.8 eV or more, 1.0 eV or more, or 1.5 eV or more.
  • the upper limit of the chemical shift is not particularly limited, but is often, for example, 2.0 eV or less.
  • the chemical shift of the first element X1 is obtained by the same method as the chemical shift of the peak corresponding to the 4f7 /2 orbital of Pt. When the first element X1 contains Cr, the 2p orbital is used. When the first element X1 contains Hf, Ta or W, the 4f orbital is used. The detailed method will be described later in the Examples section.
  • the phase shift film may contain elements other than Pt and the first element X1, such as one or more elements selected from the group consisting of B, C, N, O and Si.
  • the phase shift film may contain only one type of the other element, or may contain two or more types of the other elements.
  • the content of the other elements is preferably more than 0.0 atomic % and not more than 10.0 atomic %, more preferably more than 0.0 atomic % and not more than 5.0 atomic %, based on the total atoms in the phase shift film. It is also preferable that the phase shift film does not contain any other element, that is, the phase shift film is preferably made of Pt and the first element X1.
  • the refractive index n of the phase shift film is preferably 0.900 or more, more preferably 0.910 or more, and is preferably 0.950 or less, more preferably 0.940 or less, even more preferably 0.930 or less, and particularly preferably 0.920 or less, in order to make the thickness of the phase shift film thinner.
  • the extinction coefficient k of the phase shift film is preferably less than 0.060, more preferably less than 0.050, and even more preferably 0.048 or less.
  • the extinction coefficient k of the phase shift film is preferably 0.035 or more, more preferably 0.040 or more, and even more preferably 0.042 or more, in order to easily adjust the reflectance of the phase shift film to a lower value.
  • the refractive index n and the extinction coefficient k are determined by measuring the incidence angle dependency of reflectance using EUV light with a wavelength of 13.5 nm, and performing fitting on the obtained profile using the refractive index n and the extinction coefficient k as parameters.
  • the reflectance of the phase shift film to EUV light is preferably 2% or more. To obtain a sufficient phase shift effect, the reflectance of the phase shift film is preferably 9-15%.
  • the crystallinity of the phase shift film of the reflective mask blank of the present invention is low.
  • the phase shift film has low crystallinity when a diffraction chart is obtained by X-ray diffraction (XRD) and the crystallite diameter calculated using the diffraction chart is small.
  • the crystallite diameter is calculated using Scherrer's equation.
  • the full half-width of the diffraction peak with the highest intensity in the range of 2 ⁇ of 30 to 55° is used to calculate the crystallite diameter using Scherrer's equation.
  • the phase shift film is said to be non-crystalline (amorphous).
  • the crystallite size of the phase shift film is preferably 10.0 nm or less, more preferably 6.0 nm or less, and even more preferably 4.0 nm or less.
  • the lower limit of the crystallite size is not particularly limited, but is often 0.1 nm or more.
  • the phase shift film of the present invention may be non-crystalline (amorphous).
  • the thickness of the phase shift film is preferably 10 to 60 nm, and more preferably 20 to 60 nm.
  • the thickness of the phase shift film is determined by X-ray reflectivity.
  • the phase shift film preferably has resistance to dissolution in a cleaning solution.
  • the phase shift film has resistance to dissolution in a cleaning solution, the phase shift film is less likely to be removed during the etching process of the etching mask film described later, and a desired pattern is more likely to be obtained. More specifically, it is preferable that the change in the film thickness of the phase shift film is small when the phase shift film is brought into contact with an aqueous sulfuric acid-hydrogen peroxide solution (SPM). For example, when the phase shift film is etched with an SPM at 100° C.
  • SPM sulfuric acid-hydrogen peroxide solution
  • the change in film thickness before and after the etching process is preferably 1.0 nm or less, more preferably 0.5 nm or less, and even more preferably 0.2 nm or less.
  • the specific conditions for the etching process are as described in the examples below.
  • the phase shift film preferably contains Ta as the first element X1.
  • the content of Ta in the phase shift film may be within the above-mentioned preferred range.
  • the phase shift film can be formed by a known film forming method such as magnetron sputtering, ion beam sputtering, etc.
  • a PtTa film is formed as the phase shift film by magnetron sputtering
  • a Pt target and a Ta target are used, and a gas containing Ar gas is supplied to perform sputtering from each target, thereby forming the phase shift film.
  • the target used for sputtering may be, for example, a Pt-Ta alloy target (PtTa target), that is, an alloy target containing Pt and the first element X1 may be used.
  • the reflective mask blank of the present invention may have an etching mask film on the side of the phase shift film opposite to the substrate side.
  • the etching mask film is preferably made of a material having high resistance to dry etching. When the etching mask film is formed on the phase shift film, dry etching can be performed even if the minimum line width of the phase shift film pattern is small. Therefore, it is effective for miniaturizing the phase shift film pattern.
  • the etching mask film preferably contains one or more elements selected from the group consisting of Al, Si, Ti, Cr, Y, Nb, Mo, Ta, and Hf (hereinafter, also referred to as "third element X3"). That is, the material constituting the etching mask film preferably contains the third element X3. It is also preferable that the etching mask film further contains one or more elements selected from the group consisting of B, C, N, O and F.
  • Examples of materials constituting the etching mask film include a simple substance of the third element X3, a boride, an oxide, a nitride, an oxynitride, a carbide, a carbonitride, a carbonate, a fluoride, and an oxyfluoride of the third element X3.
  • the material constituting the etching mask film may be a composite compound (e.g., a composite oxide) containing two or more elements of the third element X3.
  • Cr-based materials containing Cr as the third element X3 include materials containing Cr and one or more elements selected from the group consisting of Cr and O, N, C, and H, and more specifically, include CrO, CrN, CrON, etc.
  • the notation "CrON" represents a material containing Cr, O, and N, and the following similar notations have the same meaning.
  • examples of Si-based materials containing Si as the third element X3 include materials containing Si and one or more elements selected from the group consisting of O, N, C, and H, and more specifically, include SiO2 , SiON, SiN, SiO, Si, SiC, SiCO, SiCN, and SiCON.
  • the reflective mask blank of the present invention may have a conductive film on a surface (second main surface) opposite to the first main surface of the substrate.
  • the reflective mask blank can be handled by an electrostatic chuck.
  • the conductive film preferably has a low sheet resistance, for example, preferably 200 ⁇ /sq. or less, and more preferably 100 ⁇ /sq. or less.
  • the material of the conductive film can be selected from a wide range of materials described in known documents. For example, the high dielectric constant coating described in JP-A-2003-501823, specifically, a coating made of Si, Mo, Cr, CrON, or TaSi, can be applied.
  • the material of the conductive film can be a Cr compound containing Cr and one or more selected from the group consisting of B, N, O, and C, or a Ta compound containing Ta and one or more selected from the group consisting of B, N, O, and C.
  • the thickness of the conductive film is preferably from 10 to 1,000 nm, and more preferably from 10 to 400 nm.
  • the conductive film may also have a function of adjusting stress on the second main surface side of the reflective mask blank, i.e., the conductive film can adjust the reflective mask blank to be flat by balancing with stress from various films formed on the first main surface side.
  • the conductive film can be formed by using a known film formation method, for example, a sputtering method such as magnetron sputtering or ion beam sputtering, a CVD method, a vacuum deposition method, or an electrolytic plating method.
  • a sputtering method such as magnetron sputtering or ion beam sputtering
  • CVD method a vacuum deposition method
  • electrolytic plating method for example, a known film formation method, for example, a sputtering method such as magnetron sputtering or ion beam sputtering, a CVD method, a vacuum deposition method, or an electrolytic plating method.
  • the reflective mask blank of the present invention may have other films.
  • the other films include, for example, an anti-reflection film for inspecting an absorber film pattern using inspection light (e.g., wavelength 193 to 248 nm).
  • the anti-reflection film is preferably disposed on the side opposite to the substrate side of the phase shift film.
  • the reflective mask can be obtained by patterning the phase shift film of the reflective mask blank of the present invention.
  • One example of a method for producing a reflective mask will be described with reference to FIG.
  • FIG. 2A shows a state in which a resist pattern 40 is formed on a reflective mask blank having a substrate 12, a multilayer reflective film 14, a protective film 16, and a phase shift film 18 in this order.
  • the resist pattern 40 can be formed by a known method, for example, by applying a resist onto the phase shift film 18 of the reflective mask blank, and then exposing and developing the resist pattern 40.
  • the resist pattern 40 corresponds to a pattern formed on a wafer using a reflective mask.
  • the phase shift film 18 is etched and patterned using the resist pattern 40 of FIG. 2A as a mask, and the resist pattern 40 is removed to obtain a laminate having a phase shift film pattern 18pt shown in FIG. 2B.
  • a resist pattern 41 corresponding to the frame of the exposure region is formed on the laminate of Fig. 2B, and dry etching is performed using the resist pattern 41 of Fig. 2C as a mask. The dry etching is performed until it reaches the substrate 12. After the dry etching, the resist pattern 41 is removed to obtain the reflective mask shown in Fig. 2D.
  • the dry etching used to form the phase shift film pattern 18pt may be, for example, dry etching using a Cl-based gas or dry etching using an F-based gas.
  • the resist pattern 40 or 41 may be removed by a known method, such as removal with a cleaning solution, such as sulfuric acid-hydrogen peroxide solution (SPM), sulfuric acid, ammonia water, ammonia-hydrogen peroxide solution (APM), OH radical cleaning water, and ozone water.
  • SPM sulfuric acid-hydrogen peroxide solution
  • APM ammonia water
  • OH radical cleaning water OH radical cleaning water
  • ozone water ozone water.
  • the etching mask film may be patterned using the resist pattern 40 as a mask, and dry etching may be performed using the pattern of the etching mask film as a mask.
  • a step of removing the etching mask film may be performed in the step of obtaining the reflective mask.
  • the etching mask film may also be removed at the same time.
  • the reflective mask obtained by patterning the phase shift film of the reflective mask blank of the present invention can be suitably used as a reflective mask for exposure to EUV light.
  • Example 1 The procedure for obtaining the reflective mask blank of Example 1 will be described as a representative example.
  • a SiO 2 -TiO 2 glass substrate (6-inch (152 mm) square outer diameter, 6.3 mm thick) was prepared as the substrate.
  • This glass substrate had 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 rigidity of 3.07 ⁇ 10 7 m 2 /s 2.
  • the quality assurance area of the first main surface of the substrate was polished to have a root-mean-square roughness (Rq) of 0.15 nm or less and a flatness of 100 nm or less.
  • a 100 nm thick Cr film was formed on the second main surface of the substrate by magnetron sputtering. The sheet resistance of the Cr film was 100 ⁇ / ⁇ .
  • a Mo/Si multilayer reflective film was formed on the first main surface of the substrate as a multilayer reflective film.
  • the Mo/Si multilayer reflective film was obtained by repeating the process of forming a Si film (film thickness 4.5 nm) and a Mo film (film thickness 2.3 nm) 40 times using an ion beam sputtering method, and then forming a Si film (film thickness 4.5 nm) after the 40th Mo film.
  • the total film thickness of the Mo/Si multilayer reflective film was 276.5 nm ((4.5 nm + 2.3 nm) x 40 + 4.5 nm).
  • a Ru film (thickness: 0.9 nm) was formed as a protective film on the multilayer reflective film by ion beam sputtering, and a Rh film (thickness: 1.6 nm) was formed on the Ru film by ion beam sputtering.
  • Phase shift film A PtTaW film (phase shift film) was formed on the protective film by using a multi-target magnetron sputtering apparatus under the following conditions: Targets: Pt target, Ta target, and W target Sputtering gas: Ar gas Film formation pressure: 0.3 Pa Input power: 12-120W Film formation speed: 0.3 nm/sec Film thickness: 30 nm Each target was discharged using a DC power source, and the power input to each target was adjusted to form a film having the composition shown in the table below.
  • Examples 2 to 4 A reflective mask blank for each example was obtained in the same manner as in Example 1, except that the type of target and the input power were adjusted to form a phase shift film having the composition shown in the table below (Examples 2 to 4).
  • Example 5 A reflective mask blank of each example was obtained in the same manner as in Example 1, except that the target to which power was applied was a Pt target alone and a phase shift film consisting only of Pt (Example 5) was formed.
  • optical properties The optical properties of the phase shift film formed by the above method were obtained.
  • the refractive index n and extinction coefficient k for EUV light are shown in the table below.
  • crystallite size The crystallite diameter of the phase shift film thus formed was measured by the above-mentioned method, and the results are shown in the table below.
  • the crystallite diameter of the phase shift film of each example is obtained by forming the phase shift film on the Si wafer under the same conditions as above.
  • the crystallite diameter of the phase shift film formed on the Si wafer and the crystallite diameter of the phase shift film in the reflective mask blank obtained by the above procedure are fully corresponding to each other.
  • the crystallite size is preferably 10 nm or less, more preferably 6.0 nm or less, and even more preferably 4.0 nm or less.
  • the SPM resistance of the phase shift film formed on the reflective mask blank was evaluated by the following method. First, an etching process was performed by contacting the phase shift film with SPM (75% by volume of concentrated sulfuric acid, 25% by volume of hydrogen peroxide solution) at 100° C. for 20 minutes. After the etching process, the thickness of the phase shift film was measured by XRR. For the XRR measurement, Smart Lab HTP manufactured by Rigaku Corporation was used. CuK ⁇ rays were used as the X-ray source, the tube voltage was 40 kV, and the tube current was 30 mA. For the analysis, the attached software (GlobalFit) was used.
  • the latter table shows the change in thickness of the phase shift film before and after the etching process, where negative values indicate a decrease in thickness of the phase shift film.
  • the absolute value of the change in film thickness before and after the etching treatment is preferably 1.0 nm or less, more preferably 0.5 nm or less, and even more preferably 0.2 nm or less.

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PCT/JP2024/036843 2023-11-27 2024-10-16 反射型マスクブランク、反射型マスク、反射型マスクの製造方法 Pending WO2025115438A1 (ja)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220121105A1 (en) * 2019-02-07 2022-04-21 Asml Netherlands B.V. A patterning device and method of use thereof
WO2023112767A1 (ja) * 2021-12-13 2023-06-22 Ａｇｃ株式会社 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
WO2023190696A1 (ja) * 2022-03-29 2023-10-05 株式会社トッパンフォトマスク 反射型フォトマスクブランク及び反射型フォトマスク
JP2023168532A (ja) * 2022-04-28 2023-11-24 Ａｇｃ株式会社 反射型マスクブランク

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20220121105A1 (en) * 2019-02-07 2022-04-21 Asml Netherlands B.V. A patterning device and method of use thereof
WO2023112767A1 (ja) * 2021-12-13 2023-06-22 Ａｇｃ株式会社 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
WO2023190696A1 (ja) * 2022-03-29 2023-10-05 株式会社トッパンフォトマスク 反射型フォトマスクブランク及び反射型フォトマスク
JP2023168532A (ja) * 2022-04-28 2023-11-24 Ａｇｃ株式会社 反射型マスクブランク

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