WO2025115587A1 - 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 - Google Patents

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 Download PDF

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Publication number
WO2025115587A1
WO2025115587A1 PCT/JP2024/040091 JP2024040091W WO2025115587A1 WO 2025115587 A1 WO2025115587 A1 WO 2025115587A1 JP 2024040091 W JP2024040091 W JP 2024040091W WO 2025115587 A1 WO2025115587 A1 WO 2025115587A1
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WIPO (PCT)
Prior art keywords
film
reflective mask
conductive film
mask blank
substrate
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Pending
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PCT/JP2024/040091
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English (en)
French (fr)
Japanese (ja)
Inventor
大二郎 赤木
剛 富澤
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AGC Inc
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Asahi Glass Co Ltd
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Filing date
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Application filed by Asahi Glass Co Ltd filed Critical Asahi Glass Co Ltd
Priority to JP2025522224A priority Critical patent/JP7747246B1/ja
Publication of WO2025115587A1 publication Critical patent/WO2025115587A1/ja
Priority to JP2025153206A priority patent/JP2025170142A/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
    • 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
    • G03F1/40—Electrostatic discharge [ESD] related features, e.g. antistatic coatings or a conductive metal layer around the periphery of the mask substrate

Definitions

  • the present disclosure relates to a reflective mask blank, a reflective mask, a method for manufacturing a reflective mask blank, and a method for manufacturing a reflective mask.
  • EUV extreme ultraviolet
  • EUV includes soft X-rays and vacuum ultraviolet light, and specifically refers to light with a wavelength of approximately 0.2 nm to 100 nm. At present, EUV with a wavelength of approximately 13.5 nm is mainly being considered.
  • a reflective mask In EUVL, a reflective mask is used.
  • the reflective mask has, for example, a substrate, a multilayer reflective film, and an absorbing film in that order.
  • the multilayer reflective film reflects EUV light.
  • the absorbing film absorbs EUV light.
  • the absorbing film may not only absorb EUV light, but also shift the phase of the EUV light. In other words, the absorbing film may be a phase shift film.
  • the opening pattern of the absorbing film is transferred to a target substrate such as a semiconductor substrate. Transferring includes reducing and transferring.
  • the reflective mask has a conductive film on the opposite side of the multilayer reflective film with respect to the substrate.
  • the conductive film is used, for example, to attach the reflective mask to an electrostatic chuck of an exposure device.
  • the conductive film of the reflective mask described in Patent Document 1 has a static friction coefficient of 0.25 or more measured in air. It is described that if the static friction coefficient is 0.25 or more, it is possible to suppress misalignment of the reflective mask even when the electrostatic chuck moves at high speed.
  • the electrostatic chuck of the exposure device repeatedly attaches and releases the reflective mask for the purpose of maintaining or replacing the reflective mask. During this process, the electrostatic chuck wears out. As a result, particles are sometimes generated. The particles get caught between the electrostatic chuck and the reflective mask, causing the reflective mask to deform. As a result, the transfer accuracy of the EUVL can deteriorate.
  • One aspect of the present disclosure provides a technology that reduces wear on an electrostatic chuck that electrostatically holds a reflective mask.
  • a reflective mask blank has a substrate, a multilayer reflective film that reflects EUV light, and an absorbing film that absorbs EUV light, in that order, and also has a conductive film on the opposite side of the substrate to the multilayer reflective film.
  • the conductive film has a Young's modulus of 250 GPa or less, as measured with a nanoindenter.
  • wear on the electrostatic chuck that electrostatically holds the reflective mask can be suppressed.
  • FIG. 1 is a cross-sectional view showing a reflective mask blank according to one embodiment.
  • FIG. 2 is a flowchart showing a method for manufacturing a reflective mask blank according to an embodiment.
  • FIG. 3 is a cross-sectional view showing a reflective mask according to an embodiment.
  • FIG. 4 is a flowchart showing a method for manufacturing a reflective mask according to an embodiment.
  • 5A is a cross-sectional view showing an example of S201
  • FIG. 5B is a cross-sectional view showing an example of S202
  • FIG. 5C is a cross-sectional view showing an example of S203.
  • FIG. 6 is a cross-sectional view showing an example of EUV light reflected by the reflective mask of FIG.
  • FIG. 6 is a cross-sectional view showing an example of EUV light reflected by the reflective mask of FIG. FIG.
  • FIG. 7 is a cross-sectional view showing an example of a reflective mask and an electrostatic chuck.
  • FIG. 8 is a cross-sectional view showing another example of a reflective mask and an electrostatic chuck.
  • FIG. 9 is a cross-sectional view showing an example of the arrangement of electrodes used in measuring the contact resistance.
  • FIG. 10 is a diagram showing an example of the relationship between the resistance, the inter-electrode distance, and the contact resistance.
  • the X-axis direction, the Y-axis direction, and the Z-axis direction are mutually orthogonal.
  • the Z-axis direction is perpendicular to the first major surface 10a of the substrate 10.
  • the X-axis direction is perpendicular to the incidence surface of the EUV light (the surface including the incident light beam and the reflected light beam). As shown in FIG. 6, the incident light beam is inclined toward the Y-axis positive direction as it moves toward the Z-axis negative direction, and the reflected light beam is inclined toward the Y-axis positive direction as it moves toward the Z-axis positive direction.
  • the reflective mask blank 1 has a conductive film 15 on the opposite side of the multilayer reflective film 11 with respect to the substrate 10. That is, the reflective mask blank 1 may have the conductive film 15, the substrate 10, the multilayer reflective film 11, the protective film 12, the absorbing film 13, and the hard mask film 14, in this order.
  • the conductive film 15 is formed on the second main surface 10b of the substrate 10. The second main surface 10b is the surface facing opposite to the first main surface 10a.
  • the conductive film 15 is used to attach the reflective mask 2 to an electrostatic chuck of an exposure device.
  • the reflective mask blank 1 may have a buffer film between the protective film 12 and the absorbing film 13, although this is not shown.
  • the buffer film protects the protective film 12 from a first etching gas that forms an opening pattern 13op in the absorbing film 13.
  • the buffer film is etched more slowly than the absorbing film 13. Unlike the protective film 12, the buffer film will ultimately have the same opening pattern as the opening pattern 13op of the absorbing film 13.
  • the method for manufacturing a reflective mask blank 1 includes, for example, steps S101 to S106 shown in FIG. 2.
  • step S101 a substrate 10 is prepared.
  • step S102 a conductive film 15 is formed on the second main surface 10b of the substrate 10.
  • step S103 a multilayer reflective film 11 is formed on the first main surface 10a of the substrate 10.
  • step S104 a protective film 12 is formed on the multilayer reflective film 11.
  • step S105 an absorbing film 13 is formed on the protective film 12.
  • a hard mask film 14 is formed on the absorbing film 13.
  • steps S101 to S106 is not limited to the order shown in FIG. 2.
  • the order of step S102 and steps S103 to S106 may be reversed.
  • the method for manufacturing the reflective mask blank 1 does not have to include all of steps S101 to S106.
  • the method for manufacturing the reflective mask blank 1 may further include a step of forming a functional film not shown in FIG. 2.
  • the reflective mask 2 includes, for example, the reflective mask blank 1 shown in FIG. 1, and includes an opening pattern 13op in the absorbing film 13.
  • the opening pattern 13op in the absorbing film 13 is transferred to a target substrate such as a semiconductor substrate. Transferring includes reducing and transferring. Note that the hard mask film 14 shown in FIG. 1 is not included in the reflective mask 2.
  • a method for manufacturing a reflective mask 2 has steps S201 to S204 shown in Figure 4.
  • a reflective mask blank 1 is prepared as shown in Figure 5 (A).
  • the reflective mask blank 1 includes a resist film 16 as shown in Figure 5 (A).
  • the resist film 16 is formed on a hard mask film 14.
  • An opening pattern to be transferred to the absorbing film 13 is formed in the resist film 16.
  • step S202 as shown in FIG. 5B, the hard mask film 14 is processed using a resist film 16 having an opening pattern.
  • the hard mask film 14 is exposed to a second etching gas, which etches the hard mask film 14.
  • the resist film 16 remains. As a result, the opening pattern of the resist film 16 is transferred to the hard mask film 14.
  • the second etching gas is selected according to the combination of the material of the resist film 16 and the material of the hard mask film 14, and includes, but is not limited to , a fluorine-based gas.
  • the fluorine-based gas includes at least one selected from , for example, CF4 gas , CHF3 gas, C2F6 gas, C3F6 gas, C4F6 gas, C4F8 gas, CH2F2 gas, CH3F gas, C3F8 gas, F2 gas, SF6 gas , and NF3 gas.
  • the second etching gas may include an active gas or an inert gas in addition to the fluorine- based gas.
  • the active gas includes at least one selected from, for example, O2 gas and O3 gas.
  • the inert gas includes at least one selected from, for example, N2 gas, He gas, and Ar gas.
  • the second etching gas is preferably a plasma gas.
  • step S203 as shown in FIG. 5(C), the absorbing film 13 is processed using a hard mask film 14 having an opening pattern.
  • the absorbing film 13 is exposed to a first etching gas, which etches the absorbing film 13.
  • the hard mask film 14 has a higher resistance to the first etching gas than the absorbing film 13.
  • the hard mask film 14 remains. As a result, the opening pattern of the hard mask film 14 is transferred to the absorbing film 13.
  • the first etching gas is selected according to the combination of the material of the hard mask film 14 and the material of the absorbing film 13, and includes, but is not limited to, a chlorine-based gas and an oxygen-based gas.
  • the chlorine-based gas includes at least one selected from, for example, Cl2 gas, SiCl4 gas, CHCl3 gas, CCl4 gas, and BCl3 gas.
  • the oxygen-based gas includes at least one selected from, for example, O2 gas and O3 gas.
  • the first etching gas may include an inert gas in addition to the chlorine-based gas and the oxygen-based gas.
  • the inert gas includes at least one selected from, for example, N2 gas, He gas, and Ar gas.
  • the first etching gas is preferably a plasma gas.
  • step S204 although not shown, the hard mask film 14 is removed.
  • a third etching gas is used to remove the hard mask film 14.
  • the third etching gas contains, for example, a fluorine-based gas, similar to the second etching gas. It is preferable that the third etching gas is a plasma.
  • a chemical solution may be used to remove the hard mask film 14.
  • the substrate 10 the multilayer reflective film 11, the protective film 12, the absorbing film 13, the hard mask film 14, and the conductive film 15 will be described in this order.
  • the substrate 10 is, for example, a glass substrate.
  • the material of the substrate 10 is preferably quartz glass containing TiO 2. Quartz glass has a smaller linear expansion coefficient and a smaller dimensional change due to temperature change than general soda-lime glass. Quartz glass may contain 80% to 95% by mass of SiO 2 and 4% to 17% by mass of TiO 2. When the TiO 2 content is 4% to 17% by mass, the linear expansion coefficient is approximately zero near room temperature, and there is almost no dimensional change near room temperature. Quartz glass may contain a third component or impurity other than SiO 2 and TiO 2.
  • the material of the substrate 10 may be crystallized glass in which a ⁇ -quartz solid solution is precipitated, silicon, metal, or the like.
  • the substrate 10 has a first main surface 10a and a second main surface 10b facing opposite to the first main surface 10a.
  • a multilayer reflective film 11 and the like are formed on the first main surface 10a.
  • the size of the substrate 10 is, for example, 152 mm long and 152 mm wide.
  • the vertical and horizontal dimensions may be 152 mm or more.
  • the first main surface 10a and the second main surface 10b each have a square quality assurance area in the center.
  • the size of the quality assurance area is, for example, 142 mm long and 142 mm wide.
  • the vertical and horizontal dimensions may be 142 mm or more.
  • the quality assurance area of the first main surface 10a preferably has a root-mean-square roughness (Rq) of 0.15 nm or less and a flatness of 100 nm or less. In addition, it is preferable that the quality assurance area of the first main surface 10a does not have any defects that cause phase defects.
  • the multilayer reflective film 11 reflects EUV light.
  • the multilayer reflective film 11 is, for example, a laminate of alternating high-refractive index layers and low-refractive index layers.
  • the high-refractive index layers are made of, for example, silicon (Si)
  • the low-refractive index layers are made of, for example, molybdenum (Mo), so a Mo/Si multilayer reflective film is used.
  • Ru/Si multilayer reflective film, Mo/Be multilayer reflective film, Mo compound/Si compound multilayer reflective film, Si/Mo/Ru multilayer reflective film, Si/Mo/Ru/Mo multilayer reflective film, Si/Ru/Mo/Ru multilayer reflective film, Si/Ru/Mo multilayer reflective film, and Si/Ru/Mo multilayer reflective film can also be used as the multilayer reflective film 11.
  • each layer constituting the multilayer reflective film 11 and the number of repeat units of the layers can be appropriately selected depending on the material of each layer and the reflectivity to EUV light.
  • the multilayer reflective film 11 is a Mo/Si multilayer reflective film, in order to achieve a reflectivity of 60% or more for EUV light with an incident angle ⁇ (see FIG. 6) of 6°, Mo layers with a thickness of 2.3 ⁇ 0.1 nm and Si layers with a thickness of 4.5 ⁇ 0.1 nm can be stacked so that the number of repeat units is 30 or more and 60 or less. It is preferable that the multilayer reflective film 11 has a reflectivity of 60% or more for EUV light with an incident angle ⁇ of 6°. The reflectivity is more preferably 65% or more.
  • the method for forming each layer constituting the multilayer reflective film 11 is, for example, a DC sputtering method, a magnetron sputtering method, an ion beam sputtering method, etc.
  • a DC sputtering method a DC sputtering method
  • a magnetron sputtering method a magnetron sputtering method
  • an ion beam sputtering method etc.
  • the protective film 12 is formed between the multilayer reflective film 11 and the absorbing film 13, and protects the multilayer reflective film 11.
  • the protective film 12 protects the multilayer reflective film 11 from the first etching gas when the absorbing film 13 is processed, i.e., in step S203.
  • the protective film 12 is not removed even when exposed to the first etching gas, but remains on the multilayer reflective film 11.
  • the Rh compound may contain, in addition to Rh, at least one element selected from the group consisting of N, O, C, and B. These elements reduce the resistance of the protective film 12 to the first etching gas, but improve the smoothness of the protective film 12 by reducing the crystallinity of the protective film 12. If the Rh compound has an amorphous structure or a microcrystalline structure, the X-ray diffraction profile of the Rh compound does not have a clear peak.
  • the protective film 12 is a single-layer film made of a single layer, but it may be a multi-layer film having a lower layer and an upper layer.
  • the lower layer of the protective film 12 is a layer formed in contact with the uppermost surface of the multilayer reflective film 11.
  • the upper layer of the protective film 12 is in contact with the lowermost surface of the absorbing film 13. In this way, by forming the protective film 12 into a multi-layer structure, materials with excellent predetermined functions can be used for each layer, making it possible to make the entire protective film 12 multifunctional.
  • the upper layer of the protective film 12 preferably contains at least one element selected from Ru and Rh, more preferably contains Rh, and even more preferably contains an Rh compound.
  • the lower layer of the protective film 12 preferably contains at least one element selected from Ru, Rh, Nb, Mo, Zr, Y, and Si, and more preferably contains Ru.
  • the lower layer of the protective film 12 preferably contains at least one element selected from C, N, and B in order to suppress the crystallinity of the protective film 12.
  • the thickness of the protective film 12 described below means the total film thickness of the multi-layer film. Note that a mixing layer formed by mixing the components contained in the multi-layer reflective film 11 and the components contained in the lower layer of the protective film 12 may be formed between the multi-layer reflective film 11 and the lower layer of the protective film 12.
  • the thickness of the protective film 12 is preferably 1.0 nm to 4.0 nm, more preferably 2.0 nm to 3.5 nm, and even more preferably 2.5 nm to 3.0 nm. If the thickness of the protective film 12 is 1.0 nm or more, the etching resistance is good. Furthermore, if the thickness of the protective film 12 is 4.0 nm or less, the reflectance to EUV light is good.
  • the density of the protective film 12 is preferably 10.0 g/cm 3 to 14.0 g/cm 3. If the density of the protective film 12 is 10.0 g/cm 3 or more, the etching resistance is good. Furthermore, if the density of the protective film 12 is 14.0 g/cm 3 or less, the decrease in reflectance for EUV light can be suppressed.
  • the method for forming the protective film 12 is, for example, DC sputtering, magnetron sputtering, ion beam sputtering, etc.
  • the Rh film is formed by DC sputtering
  • an example of the film formation conditions is as follows. ⁇ Conditions for forming Rh film> Target: Rh target, Sputtering gas: Ar gas, Gas pressure: 1.0 ⁇ 10 ⁇ 2 Pa to 1.0 ⁇ 10 0 Pa, Target power density: 1.0 W/cm 2 to 8.5 W/cm 2 , Film formation rate: 0.020 nm/sec to 1.000 nm/sec, Film thickness: 1 nm to 10 nm.
  • the absorbing film 13 absorbs EUV light.
  • the absorbing film 13 is a film in which an opening pattern 13op is to be formed.
  • the opening pattern 13op is not formed in the manufacturing process of the reflective mask blank 1, but is formed in the manufacturing process of the reflective mask 2.
  • the absorbing film 13 may not only absorb EUV light, but may also shift the phase of the EUV light. In other words, the absorbing film 13 may be a phase shift film.
  • the phase shift film shifts the phase of the second EUV light L2 relative to the first EUV light L1 shown in FIG. 6.
  • the first EUV light L1 is light that passes through the opening pattern 13op of the absorbing film 13 without being absorbed by the absorbing film 13, is reflected by the multilayer reflective film 11, and passes through the opening pattern 13op of the absorbing film 13 without being absorbed by the absorbing film 13 again.
  • the second EUV light L2 is light that passes through the absorbing film 13 while being absorbed by the absorbing film 13, is reflected by the multilayer reflective film 11, and passes through the absorbing film 13 while being absorbed by the absorbing film 13 again.
  • the phase difference ( ⁇ 0) between the first EUV light L1 and the second EUV light L2 is, for example, 170° to 250°.
  • the phase of the first EUV light L1 may be ahead of or behind the phase of the second EUV light L2.
  • the absorbing film 13 uses the interference between the first EUV light L1 and the second EUV light L2 to improve the contrast of the transferred image.
  • the transferred image is an image of the opening pattern 13op of the absorbing film 13 transferred onto the target substrate.
  • the so-called projection effect occurs.
  • the shadowing effect is caused by the fact that the incident angle ⁇ of the EUV light is not 0° (for example, 6°), resulting in an area near the sidewall of the opening pattern 13op where the sidewall blocks the EUV light, causing a positional or dimensional shift in the transferred image.
  • it is effective to lower the height of the sidewall of the opening pattern 13op, and thinning the absorbing film 13 is also effective.
  • the thickness of the absorbing film 13 is, for example, 60 nm or less, and preferably 50 nm or less, in order to reduce the shadowing effect.
  • the thickness of the absorbing film 13 is preferably 20 nm or more, and more preferably 30 nm or more, in order to ensure a phase difference between the first EUV light L1 and the second EUV light L2.
  • the absorbing film 13 In order to reduce the thickness of the absorbing film 13 to reduce the shadowing effect while maintaining the phase difference between the first EUV light L1 and the second EUV light L2, it is effective to reduce the refractive index n of the absorbing film 13. Also, in order to reduce the reflectance for the second EUV light L2, it is effective to increase the extinction coefficient k of the absorbing film 13. Thus, the absorbing film 13 is required to have excellent optical properties.
  • the absorbing film 13 is a single layer film consisting of a single layer, but it may be a multi-layer film having a lower layer and an upper layer.
  • the lower layer and upper layer constituting the absorbing film 13 are formed on the protective film 12 in this order.
  • the uppermost layer of the absorbing film 13 is the layer furthest from the protective film 12.
  • the uppermost layer of the absorbing film 13 preferably contains at least one metal element selected from Cr, Ta, Nb, Ir, Pt, Pd, Os, Re, Au, and Ru, and more preferably contains a compound of the metal element.
  • the thickness of the absorbing film 13 means the total film thickness of the multi-layer film.
  • the method for forming the absorbing film 13 is, for example, a DC sputtering method, a magnetron sputtering method, an ion beam sputtering method, etc.
  • the nitrogen content of the absorbing film 13 can be controlled by the content of N2 gas in the sputtering gas.
  • TaN film formation conditions ⁇ TaN film formation conditions> Target: Ta target, Power density of Ta target: 1.0 W/cm 2 to 8.5 W/cm 2 , Sputtering gas: a mixture of Ar gas and N2 gas, Volume ratio of N2 gas in the sputtering gas ( N2 /(Ar+ N2 )): 0.01 to 0.25, Gas pressure: 1.0 ⁇ 10 ⁇ 2 Pa to 1.0 ⁇ 10 0 Pa, Power density of Ta target: 1.0 W/cm 2 to 8.5 W/cm 2 , Film formation rate: 0.020 nm/sec to 0.060 nm/sec, Film thickness: 20 nm to 60 nm.
  • the hard mask film 14 is formed on the opposite side of the protective film 12 with respect to the absorbing film 13 as a reference, and is used to form an opening pattern 13op in the absorbing film 13.
  • the hard mask film 14 enables the resist film 16 to be thinned.
  • the thickness of the hard mask film 14 is preferably 2 nm or more and 30 nm or less, more preferably 2 nm or more and 25 nm or less, and even more preferably 2 nm or more and 10 nm or less.
  • the hard mask film 14 can be formed, for example, by DC sputtering, magnetron sputtering, or ion beam sputtering.
  • the conductive film 15 is formed on the opposite side of the multilayer reflective film 11 with respect to the substrate 10, and is used to attract the reflective mask 2 to an electrostatic chuck 21 of an exposure device 20.
  • the electrostatic chuck 21 has an electrode 22 that generates an electrostatic attraction force, an insulating stage 23 in which the electrode 22 is embedded, and a number of insulating burls 24 that protrude from the stage 23.
  • the multiple burls 24 come into contact with the conductive film 15.
  • Each of the multiple burls 24 is cylindrical in this embodiment, but may also be a tapered cone.
  • the electrostatic chuck 21 repeatedly attracts and releases the reflective mask 2 for the purpose of maintaining or replacing the reflective mask 2.
  • the Young's modulus of the conductive film 15 measured with a nanoindenter is 250 GPa or less so that the burr 24 of the electrostatic chuck 21 does not wear out.
  • the nanoindenter performs quasi-static indentation tests on the sample to obtain the mechanical properties of the sample.
  • the nanoindenter is not limited to, but is, for example, an iMicro manufactured by KLA. Young's modulus is calculated, for example, using the Continuous Stiffness Measurement Method (CSM). In order to eliminate the influence of the substrate 10 as much as possible, the Young's modulus is the value when the indentation depth is 1/3 the film thickness of the conductive film 15.
  • CSM Continuous Stiffness Measurement Method
  • the conductive film 15 is a single-layer film made of a single layer, but it may be a multi-layer film having a lower layer 15A and an upper layer 15B as shown in FIG. 8.
  • the lower layer 15A and upper layer 15B constituting the conductive film 15 are formed on the substrate 10 in this order.
  • the lower layer 15A contacts the substrate 10.
  • the upper layer 15B contacts multiple burls 24.
  • the lower layer 15A of the conductive film 15 does not have to be in contact with the substrate 10, and another functional film may be formed between the conductive film 15 and the substrate 10.
  • the conductive film 15 may have an intermediate layer between the lower layer 15A and the upper layer 15B.
  • the Young's modulus of the conductive film 15 is measured with a nanoindenter after all layers constituting the conductive film 15 are formed on the substrate 10. Even if the conductive film 15 is a multi-layer film, the Young's modulus is measured when the indentation depth is 1/3 of the thickness of the conductive film 15 in order to eliminate the influence of the substrate 10 as much as possible.
  • the conductive film 15 is sufficiently soft. This makes it possible to suppress wear of the burl 24 of the electrostatic chuck 21 and suppress the generation of particles. Particles get caught between the electrostatic chuck 21 and the reflective mask 2 and deform the reflective mask 2. As a result, the transfer accuracy of the EUVL can be deteriorated. According to this embodiment, the generation of particles can be suppressed and the transfer accuracy of the EUVL can be improved.
  • the Young's modulus of the conductive film 15 measured with a nanoindenter is preferably 250 GPa or less, more preferably 220 GPa or less, and even more preferably 200 GPa or less.
  • the Young's modulus of the conductive film 15 measured with a nanoindenter is preferably 100 GPa or more, and more preferably 120 GPa or more.
  • the conductive film 15 is a single layer film, from the viewpoint of conductivity and stability, it is preferable that the conductive film 15 contains at least one metal element selected from Cr and Ta. It is preferable that the conductive film 15 contains a compound of the above metal element.
  • the compound preferably contains at least one nonmetal element selected from N, O, C, B, and Si.
  • the total content of N, O, C, B, and Si in the compound is preferably 30 at% or less.
  • the content of each element in the conductive film 15 is determined by a value obtained by analysis using X-ray photoelectron spectroscopy (XPS).
  • XPS X-ray photoelectron spectroscopy
  • the Ta content is preferably 70 at% or more, more preferably 75 at% or more, and even more preferably 80 at% or more.
  • the Ta content is preferably 95 at% or less, more preferably 90 at% or less, and even more preferably 85 at% or less.
  • the B content is preferably 5 at% or more, more preferably 10 at% or more, and even more preferably 15 at% or more.
  • the B content is preferably 30 at% or less, more preferably 25 at% or less, and even more preferably 20 at% or less.
  • the lower layer 15A preferably contains at least one metal element selected from Cr and Ta from the viewpoints of conductivity and stability.
  • the lower layer 15A preferably contains a compound of the above metal elements.
  • the compound preferably contains at least one nonmetallic element selected from N, C, B and Si. Among these nonmetallic elements, N is most preferable from the viewpoint of film stress adjustment.
  • the lower layer 15A preferably does not substantially contain O.
  • the O content of the lower layer 15A is preferably 0.1 at% or less.
  • the Ta content is preferably 60 at% or more, more preferably 65 at% or more, and even more preferably 70 at% or more.
  • the Ta content is preferably 95 at% or less, more preferably 90 at% or less, even more preferably 85 at% or less, and particularly preferably 80 at% or less.
  • the N content is preferably 5 at% or more, more preferably 10 at% or more, even more preferably 15 at% or more, and particularly preferably 20 at% or more.
  • the N content is preferably 40 at% or less, more preferably 35 at% or less, and even more preferably 30 at% or less.
  • the Cr content is preferably 75 at% or more, more preferably 80 at% or more, and even more preferably 85 at% or more.
  • the Cr content is preferably 95 at% or less, and more preferably 93 at% or less.
  • the N content is preferably 3 at% or more, more preferably 5 at% or more, and even more preferably 7 at% or more.
  • the N content is preferably 25 at% or less, more preferably 20 at% or less, even more preferably 15 at% or less, and particularly preferably 10 at% or less.
  • the upper layer 15B is preferably formed of a material softer than the lower layer 15A, and preferably contains at least one nonmetallic element selected from O, B, Si, and C in a total of 5 at% or more to reduce hardness.
  • O is most preferable from the viewpoint of chemical stability.
  • the total content of the above nonmetallic elements is preferably 5 at% or more, more preferably 10 at% or more, and even more preferably 20 at% or more.
  • the total content of the above nonmetallic elements is preferably 60 at% or less, and more preferably 55 at% or less.
  • the upper layer 15B preferably does not substantially contain N.
  • the N content of the upper layer 15B is preferably 0.1 at% or less.
  • the Ta content is preferably 45 at% or more, more preferably 50 at% or more, and even more preferably 55 at% or more.
  • the Ta content is preferably 80 at% or less, more preferably 75 at% or less, even more preferably 70 at% or less, and particularly preferably 65 at% or less.
  • the O content is preferably 20 at% or more, more preferably 25 at% or more, even more preferably 30 at% or more, and even more preferably 35 at% or more.
  • the O content is preferably 55 at% or less, more preferably 50 at% or less, and even more preferably 45 at% or less.
  • the Cr content is preferably 65 at% or more, more preferably 70 at% or more, and even more preferably 75 at% or more.
  • the Cr content is preferably 95 at% or less, more preferably 90 at% or less, and even more preferably 85 at% or less.
  • the O content is preferably 5 at% or more, more preferably 10 at% or more, and even more preferably 15 at% or more.
  • the O content is preferably 35 at% or less, more preferably 30 at% or less, and even more preferably 25 at% or less.
  • the upper layer 15B contains at least one metal element selected from Cr and Ta, from the viewpoint of adhesion between the upper layer 15B and the lower layer 15A. It is more preferable that the upper layer 15B and the lower layer 15A contain the same metal element. For example, it is more preferable that both the upper layer 15B and the lower layer 15A contain Cr. Alternatively, it is more preferable that both the upper layer 15B and the lower layer 15A contain Ta. Both the upper layer 15B and the lower layer 15A may contain Cr and Ta.
  • the upper layer 15B preferably has a thickness of 4 nm or more.
  • the thickness of the upper layer 15B is preferably 4 nm or more, and more preferably 6 nm or more.
  • the upper layer 15B has a lower conductivity than the lower layer 15A. Therefore, from the viewpoint of the conductivity of the conductive film 15, the thickness of the upper layer 15B is preferably 50 nm or less, and more preferably 30 nm or less.
  • the contact resistance of the conductive film 15 is preferably 1000 ⁇ 10 ⁇ 3 ⁇ cm 2 or less, more preferably 500 ⁇ 10 ⁇ 3 ⁇ cm 2 or less, and further preferably 300 ⁇ 10 ⁇ 3 ⁇ cm 2 or less.
  • the contact resistance of the conductive film 15 is obtained by arranging five disk electrodes 30A, 30B, 30C, 30D, and 30E, each having a diameter of 1.2 mm, on a line at a pitch of 2.0 mm and measuring the resistance for each inter-electrode distance D1, D2, D3, and D4, as shown in Fig. 9.
  • D1 is 0.8 mm
  • D2 is 2.8 mm
  • D3 is 4.8 mm
  • D4 is 6.8 mm.
  • a regression line is obtained by the least squares method.
  • the model formula of the regression line is as shown in Fig. 10.
  • the thickness of the conductive film 15 is preferably 50 nm to 400 nm, and more preferably 70 nm to 350 nm. If the conductive film 15 is a multi-layer film, the thickness of the conductive film 15 is the total thickness of the multi-layer film.
  • the conductive film 15 can be formed, for example, by DC sputtering, magnetron sputtering, or ion beam sputtering.
  • Example 1 The experimental data will be described below.
  • the conductive film 15 was formed on the substrate 10 under the film formation conditions shown in Table 1.
  • Examples 1 to 3 are working examples, and Examples 4 to 6 are comparative examples.
  • a SiO2 - TiO2 -based 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 ⁇ 107 m2 / s2 .
  • Example 1 a TaN film was formed as a lower layer by magnetron sputtering, and then a TaO film was formed as an upper layer by magnetron sputtering, as shown in Table 1.
  • the film formation conditions for the TaN film and the TaO film were as follows. ⁇ TaN film formation conditions> Target: Ta target, Sputtering gas: mixed gas containing 81% by volume of Ar gas and 19% by volume of N2 gas; Gas pressure: 0.23 Pa, Input power density: 2.6 W/cm 2 . ⁇ TaO film formation conditions> Target: Ta target, Sputtering gas: mixed gas containing 40% by volume of Ar gas and 60% by volume of O2 gas; Gas pressure: 0.05 Pa, Input power density: 2.7 W/cm 2 .
  • the thickness of the conductive film 15 was measured by XRR (X-ray reflectivity).
  • XRR X-ray reflectivity
  • 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.
  • the accompanying software (GlobalFit) was used.
  • the conductive film 15 was formed on the substrate 10 under the same conditions, except that the film formation conditions were changed as shown in Table 1.
  • a contamination evaluation was performed by an abrasion resistance test.
  • Table 1 a contamination evaluation of " ⁇ " means that no particles or scratches were generated on the lens surface in the abrasion resistance test, and a contamination evaluation of " ⁇ ” means that at least one of particles and scratches was generated on the lens surface in the abrasion resistance test.
  • the abrasion resistance test was performed in a vacuum as follows. First, a lens (curvature 0.18 cm, material BK-7) simulating a crowbar 24 was prepared. The lens had a TiN film on its surface. Next, the substrate 10 was placed on the vibration stage with the conductive film 15 facing upward. Next, the vibration stage was vibrated with the lens facing downward and the conductive film 15 in contact.
  • the vibration conditions were a stroke of 0.1 mm, a frequency of 14 Hz, and a vibration time of 15 hours. After that, the surface of the lens was observed with an optical microscope for the presence or absence of particles and scratches, and the abrasion resistance was evaluated.
  • Examples 1 to 3 had a Young's modulus of 250 GPa or less for the conductive film 15, so no particles or scratches were observed on the lens surface during the wear resistance test. This shows that Examples 1 to 3 are better able to suppress wear of the burr 24 of the electrostatic chuck 21 and suppress the generation of particles than Examples 4 to 6.
  • Example 1 a soft upper TaO film was formed on a hard lower layer (TaN film), and therefore, unlike Example 5, the Young's modulus of the conductive film 15 was 250 GPa or less.
  • Example 3 a soft upper CrO film was formed on a hard lower layer (CrN film), and therefore, unlike Example 4, the Young's modulus of the conductive film 15 was 250 GPa or less.
  • Example 2 the gas pressure during deposition of the conductive film 15 was higher than in Example 6, so the Young's modulus of the conductive film 15 was 250 GPa or less. It was found that even if the film type is the same, the Young's modulus of the conductive film 15 can be made 250 GPa or less if the gas pressure during deposition is high.
  • the dynamic friction coefficient and other properties were evaluated for a substrate with a conductive film formed on it, but the evaluation results for the dynamic friction coefficient and other properties were similar when the conductive film was formed as part of a reflective mask blank.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Preparing Plates And Mask In Photomechanical Process (AREA)
  • Physical Vapour Deposition (AREA)
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JP2021110952A (ja) * 2020-01-08 2021-08-02 エスアンドエス テック カンパニー リミテッド 極紫外線用反射型ブランクマスク及びフォトマスク
JP2023134572A (ja) * 2021-09-28 2023-09-27 Ａｇｃ株式会社 Ｅｕｖリソグラフィ用反射型マスクブランクおよび導電膜付き基板
JP2023138546A (ja) * 2021-05-27 2023-10-02 Ａｇｃ株式会社 導電膜付基板および反射型マスクブランク
WO2023190360A1 (ja) * 2022-04-01 2023-10-05 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、および反射型マスクの製造方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2021110952A (ja) * 2020-01-08 2021-08-02 エスアンドエス テック カンパニー リミテッド 極紫外線用反射型ブランクマスク及びフォトマスク
JP2023138546A (ja) * 2021-05-27 2023-10-02 Ａｇｃ株式会社 導電膜付基板および反射型マスクブランク
JP2023134572A (ja) * 2021-09-28 2023-09-27 Ａｇｃ株式会社 Ｅｕｖリソグラフィ用反射型マスクブランクおよび導電膜付き基板
WO2023190360A1 (ja) * 2022-04-01 2023-10-05 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、および反射型マスクの製造方法

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