Classifications

• • 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
  • G03F1/62—Pellicles, e.g. pellicle assemblies, e.g. having membrane on support frame; Preparation thereof
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/15—Nano-sized carbon materials
  • C01B32/158—Carbon nanotubes
  • C01B32/168—After-treatment
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/15—Nano-sized carbon materials
  • C01B32/158—Carbon nanotubes
  • C01B32/168—After-treatment
  • C01B32/174—Derivatisation; Solubilisation; Dispersion in solvents
• • 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
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70008—Production of exposure light, i.e. light sources
  • G03F7/70033—Production of exposure light, i.e. light sources by plasma extreme ultraviolet [EUV] sources
• • 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
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
  • G03F7/70983—Optical system protection, e.g. pellicles or removable covers for protection of mask
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2202/00—Structure or properties of carbon nanotubes
  • C01B2202/02—Single-walled nanotubes
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2202/00—Structure or properties of carbon nanotubes
  • C01B2202/20—Nanotubes characterized by their properties
  • C01B2202/26—Mechanical properties
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2202/00—Structure or properties of carbon nanotubes
  • C01B2202/20—Nanotubes characterized by their properties
  • C01B2202/34—Length
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2202/00—Structure or properties of carbon nanotubes
  • C01B2202/20—Nanotubes characterized by their properties
  • C01B2202/36—Diameter

Definitions

• This disclosure relates to nanotube pellicle films, pellicles, exposure masters, and exposure devices.
• Photolithography uses a transparent substrate (hereafter referred to as a "photomask") with a pattern formed on one side.
• a pellicle is attached to the photomask to prevent foreign matter such as dust from adhering to the surface of the photomask.
• the pellicle comprises a pellicle film through which the exposure light passes, and a pellicle frame that supports the pellicle film.
• Patent Document 1 discloses a pellicle film used in extreme ultraviolet lithography using extreme ultraviolet (hereinafter also referred to as "EUV").
• the pellicle film disclosed in Patent Document 1 contains a plurality of carbon nanotubes (hereinafter also referred to as "CNTs”) that form a network structure.
• the thickness of the network structure is 3 nm to 100 nm.
• the EUV transmittance of the network structure is 92% or more.
• the plurality of CNTs contain at least 50% or more double-walled carbon nanotubes.
• Patent document 1 International Publication No. 2022/060877
• EUV exposure is performed by moving a pellicle-attached photomask, which has a pellicle attached to it, at high speed. If the pellicle film is relatively thick, the EUV transmittance may decrease, and EUV exposure may take a long time. On the other hand, if the pellicle film is thin, it may be prone to rupture. Therefore, there is a demand for a pellicle film that is less likely to rupture even if it is thin.
• An object of the present disclosure is to provide a nanotube pellicle film, a pellicle, an exposure master, and an exposure apparatus that are resistant to rupture even when the film thickness is thin.
• Means for solving the above problems include the following embodiments.
• the nanotube has a tube diameter of 0.8 nm to 6.0 nm,
• a plurality of single-walled nanotubes are included, The nanotube pellicle film according to ⁇ 1> or ⁇ 2>, wherein the content of the plurality of single-walled nanotubes is 80 mass % or more with respect to the total amount of the nanotube pellicle film.
• ⁇ 4> The nanotube pellicle film according to any one of ⁇ 1> to ⁇ 3>, wherein the ratio is 0.015 [Pa ⁇ cm 2 /(sccm ⁇ nm)] to 0.130 [Pa ⁇ cm 2 /(sccm ⁇ nm)].
• a plurality of carbon nanotubes are included, A nanotube pellicle film according to any one of ⁇ 1> to ⁇ 4>, wherein the ratio of the intensity of the G band measured by a resonance Raman scattering measurement method to the intensity of the D band measured by a resonance Raman scattering measurement method is 5 or more.
• a nanotube-containing material is one selected from the group consisting of carbon nanotubes, boron nitride nanotubes, and transition metal disulfide nanotubes; the transition metal disulfide nanotubes comprise a transition metal disulfide;
• the transition metal disulfide is represented by MX2 ; M is at least one selected from the group consisting of Mo, W, Pd, Pt, and Hf;
• M is at least one selected from the group consisting of Mo, W, Pd, Pt, and Hf;
• ⁇ 7> The nanotube pellicle film according to ⁇ 6>, wherein the nanotube is a carbon nanotube.
• ⁇ 8> The nanotube pellicle film according to any one of ⁇ 1> to ⁇ 7>, having a transmittance of extreme ultraviolet light of 88% or more.
• ⁇ 9> The nanotube pellicle film according to any one of ⁇ 1> to ⁇ 8>, wherein the maximum stress is 120 MPa or more.
• ⁇ 10> The nanotube pellicle film according to any one of ⁇ 1> to ⁇ 9>, wherein the amount of deflection when made into a square with sides of 1 cm is 200 ⁇ m or less.
• ⁇ 11> A pellicle frame, The pellicle membrane according to any one of ⁇ 1> to ⁇ 10>, which is supported by the pellicle frame;
• the pellicle comprises: ⁇ 12> A photomask;
• An exposure master comprising: ⁇ 13> An extreme ultraviolet light source that emits extreme ultraviolet light as exposure light;
• the exposure master according to ⁇ 12> an optical system that guides the exposure light emitted from the extreme ultraviolet light source to the exposure master; Equipped with an exposure apparatus, the exposure master being disposed so that the extreme ultraviolet light emitted from the extreme ultraviolet light source is transmitted through the nanotube pellicle film and irradiated onto the photomask;
• One embodiment of the present disclosure provides a nanotube pellicle film, pellicle, and exposure master that is resistant to rupture even when the film is thin.
• FIG. 1 is a schematic diagram showing a measurement device for a bulge test.
• FIG. 2 is a graph showing the pressure difference between the inside and outside of the pellicle versus time in a bulge test.
• EUV extreme ultraviolet
• Ratio air flow resistance/film thickness
• the ratio is 0.015 [Pa ⁇ cm 2 /(sccm ⁇ nm)], and preferably 0.015 [Pa ⁇ cm 2 /(sccm ⁇ nm)] to 0.130 [Pa ⁇ cm 2 /(sccm ⁇ nm)]. This makes it difficult for the film to break even if it is thin, and reduces the amount of film deflection even when the pressure is increased or decreased in the usage environment, thereby suppressing interference with the device.
• the ratio (air flow resistance/membrane thickness) is more preferably 0.100 [Pa ⁇ cm 2 /(sccm ⁇ nm)] or less, even more preferably 0.080 [Pa ⁇ cm 2 /(sccm ⁇ nm)] or less, and even more preferably 0.070 [Pa ⁇ cm 2 /(sccm ⁇ nm)] or less.
• Methods for adjusting the ratio (air flow resistance/film thickness) to 0.015 [Pa ⁇ cm 2 /(sccm ⁇ nm)] or more include, for example, a method using an ultra-high pressure homogenizer and a method with a large classification effect (for example, a method using an angle (solid-angle rotor) method for centrifugation).
• the transmittance of the NT pellicle film for extreme ultraviolet rays (hereinafter also referred to as "EUV transmittance”) is preferably 88% or more. This allows the EUV irradiation time during EUV exposure to be shorter than when the EUV transmittance is less than 88%. From the viewpoint of further shortening the EUV irradiation time, etc., the higher the EUV transmittance, the more preferable.
• the EUV transmittance is more preferably 90% or more, further preferably 92% or more, and most preferably 100%. From these viewpoints, the EUV transmittance may be 88% to 100%.
• the EUV transmittance is measured by a photodiode. Specifically, the EUV transmittance is expressed as the ratio of the current value detected with the NT pellicle film installed to the current value detected without the NT pellicle film installed. The EUV transmittance tends to decrease linearly with increasing thickness of the NT pellicle film.
• One way to adjust the EUV transmittance of the NT pellicle film to 88% or more is, for example, to make the film thinner.
• Maximum stress refers to an index of the mechanical strength of the NT pellicle film, which is independent of the film thickness of the NT pellicle film.
• the method for calculating the maximum stress is the same as the method described in the examples.
• the maximum stress of the NT pellicle film is 120 MPa or more, which indicates that the NT pellicle film has excellent mechanical strength.
• EUV exposure the inside of the exposure device is evacuated before EUV exposure is performed. If the maximum stress of the NT pellicle film is 120 MPa or more, the NT pellicle film is unlikely to break even if the stress caused by the evacuation acts on the NT pellicle film.
• the maximum stress of the NT pellicle membrane is preferably as high as possible from the viewpoint of improving the mechanical strength of the NT pellicle membrane, more preferably 130 MPa or more, even more preferably 140 MPa or more, and even more preferably 280 MPa or more.
• the maximum stress of the NT pellicle membrane is preferably 500 MPa or less, more preferably 400 MPa or less, from the viewpoint of rupturing the membrane when recovering the membrane, making it easier to recover the membrane. From these viewpoints, the maximum stress of the NT pellicle membrane may be 120 MPa to 500 MPa.
• the method for measuring the maximum stress of the NT pellicle membrane was the same as that described in the examples.
• the lower limit of the amount of deflection of the NT pellicle membrane is not particularly limited, but may be, for example, 0 ⁇ m or more, or 1 ⁇ m or more. From these viewpoints, the amount of deflection of the NT pellicle membrane may be 0 ⁇ m to 200 ⁇ m, 0 ⁇ m to 50 ⁇ m, or 1 ⁇ m to 50 ⁇ m.
• the method for measuring the amount of deflection of the NT pellicle membrane when cut into a square with one side measuring 1 cm is as follows.
• the NT pellicle film is fixed in a chamber for bulge testing so that the free-standing film portion of the NT pellicle film has a square shape of 1 cm x 1 cm.
• a displacement meter e.g., "LJ-V7200" manufactured by Keyence Corporation
• the inside of the chamber is pressurized by flowing compressed air into the chamber at 10 sccm.
• the amount of displacement of the position of the center of the free-standing film portion in the pressurized state relative to the position of the center of the free-standing film portion in the state where compressed air is not flowing inside the chamber is defined as the amount of deflection.
• the amount of displacement is measured by a displacement meter.
• the deflection amount can be derived by transferring the pellicle membrane to a frame so that the free-standing membrane portion is 1 cm x 1 cm and then measuring the amount of deflection.
• One way to adjust the deflection of the NT pellicle membrane to 200 ⁇ m or less when it is cut into a square with sides of 1 cm is to reduce the air resistance of the NT pellicle membrane.
• Nanotubes NTs may be single-walled nanotubes (hereinafter also referred to as “single-walled NTs”) or multi-walled nanotubes (hereinafter also referred to as “multi-walled NTs").
• single-walled nanotube refers to a single-walled nanotube.
• Multi-walled nanotube refers to a multi-walled nanotube.
• NTs usually form a bundle.
• the number of NTs forming a bundle is 3 or more, preferably 4 to 100, and more preferably 5 to 50.
• the NT pellicle membrane may contain NTs that do not form a bundle.
• the NT tube diameter (i.e., the width of the NT) may be 0.4 nm to 50 nm.
• the NT tube diameter is preferably 0.5 nm or more, more preferably 0.6 nm or more, even more preferably 0.7 nm or more, and particularly preferably 0.8 nm or more.
• the NT tube diameter is preferably 30 nm or less, more preferably 15 nm or less, even more preferably 10 nm or less, and particularly preferably 6 nm or less.
• the NT tube diameter may be 0.4 nm to 50 nm, 0.4 nm to 15 nm, 0.4 nm to 10 nm, 0.4 nm to 6 nm, or 0.8 nm to 6 nm.
• the length of the NTs is preferably 10 nm or more. When the length of the NTs is 10 nm or more, the NTs are well entangled with each other, and the mechanical strength of the NT pellicle film is excellent.
• the length of the NTs is preferably 10 cm or less, more preferably 1 cm or less, and even more preferably 100 ⁇ m or less. From these viewpoints, the length of the NTs is preferably 10 nm to 10 cm, more preferably 10 nm to 1 cm, and even more preferably 10 nm to 100 ⁇ m.
• the outer diameter and length of the NT tubes are the arithmetic average values measured for 20 or more carbon materials (primary particles) by observation under an electron microscope.
• an electron microscope a scanning electron microscope (SEM), a transmission electron microscope (TEM), or the like can be used.
• the effective length of the NT is preferably 0.1 ⁇ m or more, more preferably 0.5 ⁇ m or more, and even more preferably 1.0 ⁇ m or more.
• the effective length of the NT may be 30 ⁇ m or less, 20 ⁇ m or less, or 10 ⁇ m or less.
• the effective length of the NT is measured by the following method. First, the far-infrared spectrum of the NT pellicle film is measured using a Fourier transform infrared spectrometer (for example, Bruker's FT-IR spectrometer Vertex 80v). The NT pellicle film is then transferred onto a high resistivity (i.e. low carrier density) Si substrate. According to the methods described in References 2 to 4, the effective length of the NT is evaluated by estimating the "effective length of the NT" NT channel consisting of a conductive path affected by kinks, defects, etc. from the peak value of the plasmon resonance.
• the average value of the tube diameter is used to calculate the effective length of the NT.
• the average value of the tube diameter can be obtained by a method of obtaining the average diameter of NTs by imaging the NTs with an electron microscope.
• NTs with few kinks and defects may be NTs with high crystallinity and excellent linearity.
• the NT pellicle film contains multiple nanotubes with tube diameters of 0.8 nm to 6.0 nm, and it is preferable that the content of multiple nanotubes with tube diameters of 0.8 nm to 6.0 nm is 80 mass% or more relative to the total amount of the nanotube pellicle film.
• the NT pellicle film preferably contains a plurality of single-walled nanotubes, and the content of the plurality of single-walled nanotubes is preferably 80 mass% or more relative to the total amount of the nanotube pellicle film.
• the NTs contained in the NT pellicle film are not particularly limited.
• the NT pellicle film includes a plurality of nanotubes, and the nanotubes are preferably one selected from the group consisting of carbon nanotubes, boron nitride nanotubes, and transition metal disulfide nanotubes.
• the transition metal disulfide nanotubes include a transition metal disulfide.
• the transition metal disulfide is represented by MX2 .
• M is at least one selected from the group consisting of Mo, W, Pd, Pt, and Hf.
• X is at least one selected from the group consisting of S, Se, and Te.
• the nanotubes preferably include carbon nanotubes, and are preferably carbon nanotubes.
• CNTs have high mechanical strength. By using CNTs as the NTs, the mechanical strength of the NT pellicle film is superior to that of NT pellicle film made of SiN, polysilicon, etc.
• the transition metal disulfide nanotubes may be comprised of a transition metal disulfide.
• the transition metal disulfide may be MoS2 , MoSe2 , WS2 , or WSe2 .
• an NT pellicle film containing multiple CNTs will also be referred to as a "CNT pellicle film.”
• Ratio (G/D) The ratio of the G band intensity measured by the resonance Raman scattering measurement method to the D band intensity measured by the resonance Raman scattering measurement method of the CNT pellicle film (hereinafter also referred to as "ratio (G/D)") is preferably 5 or more. .
• the "ratio of the G band intensity measured by resonance Raman scattering measurement to the D band intensity measured by resonance Raman scattering measurement of a CNT pellicle film” is an index showing the degree of structural defects in each of the multiple CNTs contained in the CNT pellicle film.
• “Defects” include the introduction of topological defects in a network (mesh) in which carbon atoms constituting a CNT are covalently bonded. Topological defects include five-membered rings and seven-membered rings.
• the "G band” is the main Raman active mode of the graphite structure, originating from sp2 bonded carbon, which represents the planar structure of the CNT.
• the "D band” is a mode originating from disorder or defects, originating from structural defects or open ends of the CNT. The higher the ratio (G/D), the fewer the structural defects of each of the multiple CNTs contained in the CNT pellicle film.
• a photomask with a reflective layer that reflects EUV is used, and the photomask and optical system are placed in a vacuum chamber. EUV exposure is performed in a vacuum atmosphere. However, residual gas (e.g., moisture and organic matter) remains in the vacuum chamber, and EUV irradiation may cause carbon film adhesion (hereinafter referred to as "contamination") on the surface of the mirror or mask included in the optical system. The occurrence of contamination may cause a decrease in throughput and deterioration of transfer performance. As a countermeasure against contamination, hydrogen gas is supplied into the vacuum chamber and the generated contamination is cleaned in situ, without disassembling and cleaning the optical system.
• a ratio (G/D) of 5 or more indicates that the number of structural defects in each of the multiple CNTs contained in the CNT pellicle film is small. If the ratio (G/D) is 15 or more, etching of the CNTs is less likely to be promoted during EUV exposure than when the ratio (G/D) is less than 5. In other words, the CNT pellicle film is less likely to be reduced in thickness even when exposed to hydrogen plasma. As a result, the excellent mechanical strength of the CNT pellicle film is maintained. From the viewpoint of maintaining the mechanical strength of the CNT pellicle film, the higher the ratio (G/D), the more preferable, and the ratio is more preferably 7 or more, even more preferably 15 or more, and particularly preferably 25 or more.
• the ratio (G/D) may be 100 or less, or may be 20 or less. From these viewpoints, the ratio (G/D) may be 5 to 20.
• the ratio (G/D) is measured by a resonance Raman scattering measurement method using a laser wavelength of 532 nm.
• the ratio (G/D) may be measured using an "NRS-5100" manufactured by JASCO Corporation.
• Raman imaging measurements are performed on a 10 mm x 10 mm freestanding CNT pellicle film at 10 measurement points spaced 1 mm apart.
• the D band intensity is the maximum value among the 10 measurement points of the Raman scattering intensity in the Raman shift range of 1300 cm -1 to 1400 cm -1 .
• the G band intensity is the maximum value among the 10 measurement points of the Raman scattering intensity in the Raman shift range of 1550 cm -1 to 1610 cm -1 .
• the Raman spectrum of a CNT pellicle film reflects the average structure of the CNT chains present within the irradiation area where the CNT pellicle film is irradiated with a laser.
• the laser irradiation size is about 100 ⁇ m in diameter.
• the total length of the single-walled CNTs contained within a spot diameter of 100 ⁇ m in diameter is estimated to be about 1000 ⁇ m to 2000 ⁇ m. Furthermore, assuming that the length of one CNT is 1 ⁇ m, the total number of CNTs constituting the CNT pellicle film contained within the above-mentioned spot diameter of 100 ⁇ m is about 1000 to 2000. From these facts, the structural information obtained by a typical Raman microspectrometer reflects the average structural information of 1000 or more CNTs (length 1000 ⁇ m or more).
• the film thickness of the NT pellicle film is not particularly limited and may be 2 nm to 200 nm. From the viewpoint of increasing the EUV transmittance, the thickness of the NT pellicle film is preferably 100 nm or less, more preferably 50 nm or less, even more preferably 40 nm or less, and particularly preferably 30 nm or less.
• the thickness of the NT pellicle membrane is preferably 3 nm or more, more preferably 4 nm or more, and even more preferably 6 nm or more.
• the film thickness of the NT pellicle film is measured by transferring the free-standing film portion of the NT pellicle film onto a silicon substrate and using a reflection spectroscopic film thickness meter (F50-UV manufactured by Filmetrics, Inc.). In detail, the film thickness is measured as follows.
• Free-standing membrane portion of NT pellicle membrane refers to the region of the NT pellicle membrane that is not supported by the pellicle frame. More specifically, the film thickness is measured as follows.
• the free-standing film portion of the NT pellicle film of the pellicle which will be described later, is transferred onto a silicon substrate.
• a solvent is dropped onto a silicon substrate, and the NT pellicle film of the pellicle is placed facing the silicon substrate, and the pellicle is placed on the substrate.
• the solvent include water and organic solvents.
• the solvent is dried to make the NT pellicle film adhere closely to the silicon substrate without any gaps.
• the silicon substrate is fixed and the pellicle frame of the pellicle is lifted to separate the free-standing film portion from the pellicle, and the free-standing film portion is transferred to the substrate.
• the reflectance spectrum is measured in the wavelength range of 200 nm to 600 nm at wavelength intervals of 1 nm to 2 nm.
• the reflectance spectrum is measured using a reflectance spectroscopic film thickness meter (for example, Filmetrics, model F50-UV, spot diameter 1.5 mm) as a reflectance measuring device.
• a silicon wafer is used as a reference for measuring the reflection intensity.
• the reflectance Rs( ⁇ ) is calculated by the following formula.
• Is( ⁇ ) represents the reflection intensity of a free-standing film portion on a silicon substrate at a wavelength ⁇
• Iref( ⁇ ) represents the reflection intensity of a reference
• Rref( ⁇ ) represents the absolute reflectance of the reference.
• the gain, exposure time, etc. are the same conditions in measuring the reflection intensity of the reference and the free-standing film portion on the silicon substrate. This allows the absolute reflectance of the free-standing film portion on the silicon substrate to be obtained.
• the diagonal lines of the free-standing membrane part are the X-axis and Y-axis.
• three points are set at intervals where the distance between the center points of adjacent measurement points is 2 mm
• three points in the Y-axis direction three points are set at intervals where the distance between the center points of adjacent measurement points is 2 mm.
• three points vertically x three points horizontally, a total of nine measurement points are set as the "measurement position”.
• the thickness of the free-standing film portion is calculated using the three-layer model of air layer/NT film layer/silicon substrate, using the relationship formulas (a) to (c) below.
• the reflectance Rs is expressed by the following formula (a) using the amplitude reflectance r s .
• the amplitude reflectance r s from the three layers of air layer/NT film layer/silicon substrate is expressed by the following formula (b).
• r01 represents the amplitude reflectance from the interface between the air layer and the layer of the free-standing film portion
• r12 represents the amplitude reflectance from the interface between the layer of the free-standing film portion and the silicon substrate
• i represents an imaginary unit.
• ⁇ is the phase difference that occurs when light of wavelength ⁇ makes one round trip within the film, and is expressed by the following formula (c).
• d represents the thickness of the free-standing film portion
• ⁇ represents the angle of incidence
• i represents the imaginary unit.
• the film thickness of the free-standing film portion is obtained by calculation using the least squares method with the film thickness d as a variable for the reflectance Rs in the wavelength range of 225 nm to 500 nm, using the relational expressions (a) to (c) above.
• the calculated film thickness at the "measurement position" of the free-standing film is regarded as the film thickness of the NT pellicle film.
• the pellicle of the present disclosure includes a pellicle frame and the NT pellicle membrane of the present disclosure.
• the NT pellicle membrane is supported by the pellicle frame.
• the pellicle of the present disclosure is equipped with the NT pellicle membrane of the present disclosure, and therefore exhibits the same effects as the NT pellicle membrane of the present disclosure.
• the pellicle frame is a cylindrical object.
• the pellicle frame has an end face (hereinafter, referred to as the "pellicle membrane end face") on one side in the thickness direction.
• the NT pellicle membrane may be fixed to the pellicle membrane end face via an adhesive layer.
• the adhesive constituting the adhesive layer is not particularly limited, and examples thereof include acrylic resin adhesives, epoxy resin adhesives, polyimide resin adhesives, silicone resin adhesives, inorganic adhesives, double-sided adhesive tapes, polyolefin adhesives, hydrogenated styrene adhesives, etc.
• the adhesive is a concept that includes not only adhesives but also pressure-sensitive adhesives.
• the thickness of the adhesive layer is, for example, 10 ⁇ m to 1 mm.
• the pellicle frame has an exposure through hole.
• the exposure through hole indicates a space through which light transmitted through the NT pellicle film passes to reach the photomask.
• the shape of the pellicle frame in the thickness direction of the pellicle frame is, for example, rectangular.
• the rectangular shape may be a square or a rectangle.
• the pellicle frame may have an air vent.
• the air vent is formed, for example, in a side surface of the pellicle frame. When the pellicle frame is attached to the photomask, the air vent connects the internal space of the pellicle with the external space of the pellicle.
• the rectangular pellicle frame is composed of four sides when viewed in the thickness direction.
• the length of one side in the longitudinal direction is preferably 200 mm or less.
• the size of the pellicle frame is standardized depending on the type of exposure apparatus.
• the length of one side of the pellicle frame in the longitudinal direction being 200 mm or less satisfies the standardized size for EUV exposure.
• the length of one side in the short direction is preferably 5 mm to 180 mm, more preferably 80 mm to 170 mm, and further preferably 100 mm to 160 mm.
• the height of the pellicle frame (i.e., the length of the pellicle frame in the thickness direction) is preferably 3.0 mm or less, more preferably 2.4 mm or less, and even more preferably 2.375 mm or less. This allows the pellicle frame to satisfy the size standardized for EUV exposure.
• the height of the pellicle frame standardized for EUV exposure is, for example, 2.375 mm.
• the mass of the pellicle frame is not particularly limited, but is preferably 20 g or less, and more preferably 15 g or less, which makes the pellicle frame suitable for use in EUV exposure.
• the material of the pellicle frame is not particularly limited, and examples thereof include quartz glass, metal, carbon-based materials, resin, silicon, and ceramic-based materials.
• the metal may be a pure metal or an alloy.
• a pure metal is made of a single metal element. Examples of pure metals include aluminum and titanium.
• An alloy is made of multiple metal elements, or a metal element and a nonmetal element. Examples of alloys include stainless steel, magnesium alloys, steel, carbon steel, Invar, etc.
• resins include polyethylene, etc.
• ceramic materials include silicon nitride (SiN), silicon carbide (SiC), alumina (Al 2 O 3 ), etc.
• the structure of the pellicle frame may be a single item or an assembly.
• a single item is obtained by cutting out a single raw material plate.
• An "assembly" is an item in which multiple components are integrated together. Methods for integrating multiple components include a method using a known adhesive or a method using fastening parts. Fastening parts include bolts, nuts, screws, rivets, or pins.
• the multiple components may be made of different materials.
• the pellicle may further include an adhesive layer.
• the adhesive layer enables the pellicle to be adhered to a photomask.
• the pellicle frame has an end face (hereinafter referred to as the "photomask end face") on the other side in the thickness direction.
• the adhesive layer is formed on the photomask end face.
• the adhesive layer is a gel-like soft solid.
• the adhesive layer preferably has fluidity and cohesive strength. "Fluidity” refers to the property of coming into contact with and wetting the photomask that is the adherend.
• Cosmetic strength refers to the property of resisting peeling from the photomask.
• the adhesive layer is made of an adhesive resin.
• the adhesive resin is not particularly limited, and examples thereof include an acrylic adhesive, a silicone adhesive, a styrene adhesive, a urethane adhesive, and an olefin adhesive.
• the thickness of the adhesive layer is not particularly limited, and is preferably 10 ⁇ m to 500 ⁇ m.
• Exposure Master The exposure master of the present disclosure includes a photomask and the pellicle of the present disclosure.
• the pellicle of the present disclosure is attached to the photomask.
• the exposure master of the present disclosure is equipped with the pellicle of the present disclosure, and therefore exhibits the same effects as the pellicle of the present disclosure.
• the method for attaching the photomask to the pellicle (hereinafter referred to as the "attachment method") is not particularly limited, and examples include the above-mentioned method using the adhesive layer, the method using fastening parts, and the method using the attractive force of magnets, etc.
• the photomask has a support substrate, a reflective layer, and an absorber layer.
• the support substrate, the reflective layer, and the absorber layer are preferably stacked in this order.
• the pellicle is attached to the side of the photomask on which the reflective layer and the absorber layer are provided.
• the absorber layer partially absorbs the EUV light, forming a desired image on a sensitive substrate (e.g., a semiconductor substrate with a photoresist film).
• the reflective layer may be a multilayer film of molybdenum (Mo) and silicon (Si).
• the absorber layer may be made of a material that is highly absorbent of EUV light, etc. Examples of materials that are highly absorbent of EUV light, etc. include chromium (Cr) and tantalum nitride.
• the exposure apparatus of the present disclosure includes an extreme ultraviolet light source that emits extreme ultraviolet light as exposure light, an exposure master of the present disclosure, and an optical system that guides the exposure light emitted from the EUV source to the exposure master;
• the exposure master is disposed so that the extreme ultraviolet light emitted from the extreme ultraviolet light source is transmitted through the nanotube pellicle film and irradiated onto the photomask.
• the exposure apparatus of the present disclosure has the same effects as the exposure master of the present disclosure. Furthermore, since the exposure apparatus of the present disclosure has the above-mentioned configuration, it is possible to form a fine pattern (e.g., a line width of 32 nm or less) and to perform pattern exposure with reduced resolution defects due to foreign matter.
• a publicly known extreme ultraviolet light source can be used as the extreme ultraviolet light source.
• a publicly known optical system can be used as the optical system.
• the manufacturing method of the NT pellicle membrane of the present disclosure is a method for manufacturing the NT pellicle membrane of the present disclosure.
• the manufacturing method of the NT pellicle membrane of the present disclosure includes a preparation step, a mixing step, a dispersion step, a purification step, and a film formation step.
• the preparation step, the mixing step, the dispersion step, the purification step, and the film formation step are performed in this order.
• NT raw material a nanotube raw material (hereinafter also referred to as "NT raw material”) is prepared.
• the method for preparing the NT raw material is not particularly limited, and examples thereof include a method of obtaining a commercially available product, a method of synthesizing a carbon nanotube raw material (hereinafter also referred to as a "CNT raw material"), and the like.
• Examples of commercially available products include eDIPS manufactured by Meijo Nano Carbon Co., Ltd., ZEONANO manufactured by Zeon Nano Technology Co., Ltd., and TUBALL manufactured by OCSiAl Corporation.
• Examples of the synthesis method of the CNT raw material include the enhanced direct injection pyrolytic synthesis method (hereinafter also referred to as the "eDIPS method”), the super growth method, the laser ablation method, etc.
• the eDIPS method is preferable as the synthesis method of the CNT raw material.
• the DIPS method is a gas-phase flow method in which a hydrocarbon-based solution containing a catalyst (or a catalyst precursor) and a reaction promoter is atomized by spraying the solution into a high-temperature furnace, thereby synthesizing single-walled NTs in a flowing gas phase.
• the e-DIPS method is a gas-phase flow method that improves the DIPS method.
• the "e-DIPS method” focuses on the particle formation process in which ferrocene used as a catalyst has different particle diameters on the upstream and downstream sides of a reactor, and unlike the DIPS method in which only an organic solvent is used as a carbon source, the e-DIPS method is relatively easy to decompose in the carrier gas. In other words, it is a method in which the growth point of single-walled NT is controlled by mixing a second carbon source that is likely to become a carbon source.
• the product name "MEIJOeDIPS” manufactured by Meijo Nanocarbon Co., Ltd. can be mentioned.
• the method for mixing the NT raw material and the solvent is not particularly limited, and examples include a method using a magnetic stirrer, a method using cavitation (e.g., ultrasonic dispersion, etc.), a method that mechanically applies shear force (e.g., a ball mill, a roller mill, a vibration mill, a kneader, a homogenizer, etc.), and a method using turbulence (e.g., a jet mill, a nanomizer, etc.).
• a method using a magnetic stirrer e.g., a method using cavitation (e.g., ultrasonic dispersion, etc.)
• a method that mechanically applies shear force e.g., a ball mill, a roller mill, a vibration mill, a kneader, a homogenizer, etc.
• turbulence e.g., a jet mill, a nanomizer, etc.
• the solvent is not particularly limited, and examples thereof include organic solvents, water, etc.
• organic solvents include isopropyl alcohol, ethanol, toluene, xylene, ethylbenzene, n-methylpyrrolidone, N,N-dimethylformamide, propylene glycol, methyl isobutyl ketone, etc.
• a dispersant may be mixed in.
• the dispersant can disentangle thick bundles contained in the NT raw material.
• examples of dispersants include flavin derivatives, sodium cholate, sodium deoxycholate, sodium dodecylbenzenesulfonate, polyacrylic acid, sodium polyacrylate, polyfluorene (poly(9,9-dioctylfluorenyl-2,7-diyl)), sodium dodecyl sulfate, and the like.
• An ultra-high pressure homogenizer is a device that applies high pressure to a liquid material to uniformly disperse the components (e.g., particles, etc.) in the liquid material.
• the ultra-high pressure homogenizer may be a known dispersing machine.
• the ultra-high pressure homogenizer may be either a nozzle type or a valve type, and from the viewpoint of uniformly dispersing the NT raw material in the first dispersion, the nozzle type is preferable.
• high pressure is applied to the liquid material, causing the liquid materials to collide with each other to disperse the components of the liquid material.
• the nozzle type may be an H-shaped nozzle.
• the pressure of the dispersion process is not particularly limited, but is preferably 10 MPa or more, more preferably 15 MPa to 100 MPa, and even more preferably 20 MPa to 90 MPa.
• the number of dispersion processes may be one or more. The more the number of dispersion processes is, the more likely structural defects may occur in the CNTs. In other words, the ratio (G/D) of the CNT pellicle film may decrease. Therefore, the number of dispersion processes is preferably 1 to 10 times, and more preferably 2 to 9 times.
• the centrifugation method is preferably the angle rotor method.
• the angle at which the container is tilted with respect to the direction of gravity is preferably 1° to 100°, and preferably 10° to 60°.
• the centrifugation method is preferably the angle rotor method.
• the second dispersion liquid is formed into a sheet-like film to produce the NT pellicle membrane of the present disclosure.
• the CNT film floating on the water surface was scooped up with a silicon frame.
• the silicon frame had a square opening with a side length of 1 cm. This resulted in a pellicle film (CNT film) with a mesh structure.
• the area of the free-standing film of the CNT pellicle film i.e., the area of the opening of the silicon frame) was 1 cm2.
• Example 2 A CNT pellicle film was obtained in the same manner as in Example 1, except that in the dispersion step, the number of dispersion treatments was changed to 10.
• Example 3 A CNT pellicle membrane was obtained in the same manner as in Example 1, except that in the dispersion process, a stirring type homogenizer ("HF93" manufactured by SMT Corporation) was used instead of the ultra-high pressure homogenizer, with the stirring speed set to 11,000 rpm and the stirring time set to 60 minutes, and in the purification process, a high-speed centrifuge ("JXN-30” manufactured by Beckman Coulter, Inc.) with a fixed angle of 30 degrees (JLA-12.500, Beckman Coulter, Inc.) was used, with the purification conditions being 13,000 rpm, 11 hours, and 10°C.
• a stirring type homogenizer (“HF93” manufactured by SMT Corporation) was used instead of the ultra-high pressure homogenizer, with the stirring speed set to 11,000 rpm and the stirring time set to 60 minutes
• a high-speed centrifuge (“JXN-30” manufactured by Beckman Coulter, Inc.) with a fixed angle of 30 degrees (JLA-12.500, Beckman Co
• Comparative Example 1 A CNT pellicle membrane was obtained in the same manner as in Example 1, except that an agitation homogenizer ("HF93" manufactured by SMT Co., Ltd.) was used instead of the ultra-high pressure homogenizer in the dispersion process.
• the conditions for the dispersion process using the agitation homogenizer were an agitation speed of 11,000 rpm and an agitation time of 60 minutes.
• Example 4 A CNT pellicle membrane was obtained in the same manner as in Example 1, except that in the dispersion process, the number of dispersion treatments was changed to 10, and in the purification process, a high-speed centrifuge ("JXN-30" manufactured by Beckman Coulter, Inc.) with a fixed angle of 30 degrees (JLA-12.500, Beckman Coulter, Inc.) was used, and purification conditions were 11,000 rpm, 7 hours, and 10°C.
• JXN-30 manufactured by Beckman Coulter, Inc.
• JLA-12.500 Beckman Coulter, Inc.
• Tube diameter, etc. of CNTs The tube diameter, film thickness, ratio (G/D), and EUV transmittance were measured by the methods described above.
• FIG. 1 Airflow resistance, etc. Measured by a bulge test of the CNT pellicle membrane.
• a CNT pellicle film 10 is fixed to a chamber 20 for a bulge test.
• the free-standing film portion of the CNT pellicle film 10 is fixed to a square shape with one side measuring 1 cm.
• a displacement meter Keyence Corporation's "LJ-V7200" was placed outside the chamber 20 so as to face the CNT pellicle film 10.
• the inside of the chamber 20 was pressurized by flowing compressed air F into the chamber 20 , and a pressure ⁇ P was applied to the free-standing film portion of the CNT pellicle film 10 .
• the pressure ⁇ P applied to the CNT pellicle film 10 is represented by the difference between the pressure (atmospheric pressure) P1 outside the chamber 20 and the pressure P2 inside the chamber 20.
• the pressure P2 inside the chamber 20 was measured by a differential pressure gauge 21.
• ⁇ P is adjusted by controlling the flow rate of the compressed air flowing inside the chamber 20 with a flow meter (not shown).
• the air flow rate flowing into the chamber 20 was increased by 10 sccm at one-minute intervals until the CNT pellicle film 10 broke.
• the differential pressure ⁇ P generated at that time was recorded.
• the vertical axis represents the differential pressure ⁇ P ⁇ flow area (the flow area is 1 cm2 in Examples 1 to 4) and the horizontal axis represents the air flow rate V air , and the slope (i.e., differential pressure ⁇ P ⁇ flow area / air flow rate V air ) is calculated to determine the air flow resistance.
• the air flow resistance is divided by the film thickness to derive the air flow resistance / film thickness.
• ⁇ P represents the pressure difference (P2-P1) (Pa)
• a represents 1/2 (m) of the short side length of the free-standing membrane portion (i.e., "a” represents 0.005 m)
• d represents the amount of deflection (m) of the CNT pellicle membrane
• t represents the membrane thickness (m) of the CNT pellicle membrane.
• ultra-high pressure type refers to an ultra-high pressure homogenizer.
• agitation type refers to an agitation type homogenizer.
• Stress refers to the method of centrifugal processing being the swing rotor method.
• Angle refers to the method of centrifugal processing being the angle rotor method.
• the ratio (air flow resistance/film thickness) was less than 0.015 [Pa ⁇ cm 2 /(sccm ⁇ nm)]. Therefore, the maximum stress was less than 100 MPa. As a result, it was found that the pellicle membrane of Comparative Example 1 was not a nanotube pellicle membrane that was difficult to break even if it was thin.
• the ratio (air flow resistance/film thickness) was 0.015 [Pa ⁇ cm 2 /(sccm ⁇ nm)] or more. Therefore, the maximum stress was 100 MPa or more. As a result, it was found that the pellicle membranes of Examples 1 to 4 were nanotube pellicle membranes that were difficult to break even though they were thin.

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