Free-standing carbon nanutube composite thin films and method using the same

Abstract

The present invention relates to a carbon nanotube composite thin film including a freestanding region, and specifically, may include a frame; and a thin film including a region in which carbon nanotubes are freestanding formed on one surface of the frame.

Description

Technology Field

[0001] The present invention relates to a carbon nanotube composite thin film. Background Technology

[0003] As semiconductor microfabrication processes enter the 7nm and below range, the demand for EUV processes is rapidly increasing. The EUV (Extreme Ultra Violet) lithography process uses an extremely short wavelength of approximately 13.5nm, and the pellicle used in this process refers to a very thin film that protects the photomask from external contamination while maximizing the transmission of EUV light. Since existing EUV pellicles are difficult to manufacture and expensive, there is a growing demand in the market for alternatives that are mass-producible and reasonably priced.

[0004] Ultrathin materials such as SiN, SiC, graphene, and carbon nanotubes (CNT) have generally been proposed as candidates for EUV pellicles. However, achieving high transmittance, mechanical stability, and thermal durability simultaneously at EUV wavelengths requires highly complex processes. There are limitations, such as the need for semiconductor equipment including CVD / PVD facilities, photolithography devices, and etching chambers, as well as multi-stage deposition, etching, and patterning processes; these processes result in very high production costs due to high equipment investment and maintenance expenses, as well as the time required for multiple stages.

[0005] In addition, it is difficult to uniformly form ultra-thin films of 50 nm or less over a large area, and there is a problem that micro-defects (pinholes, non-uniform film thickness, etc.) generated during the process cause a decrease in transmittance and optical defects. SiN and SiC substrate pellicles are limited to specific process recipes, and even if carbon nanomaterials (CNT, graphene, etc.) are utilized, patterning and etching technologies are essential, which limits the difficulty of scaling up to a large area.

[0006] Therefore, there is a need to develop technology that can achieve high transmittance even at EUV wavelengths, possess physical and thermal stability, be formed as an ultrathin film over a large area, and be manufactured through a simpler process than conventional technologies to lower production costs. The problem to be solved

[0008] The present invention aims to solve the aforementioned conventional problems and provides a carbon nanotube composite film including a freestanding region of an ultrathin film that can be manufactured through a simpler process than conventional technology.

[0009] In addition, the present invention aims to provide a carbon nanotube composite thin film capable of controlling electrical, mechanical, and optical properties through the control of the orientation of carbon nanotubes and the mixing of nanoparticles. means of solving the problem

[0011] A carbon nanotube composite thin film including a freestanding region according to one embodiment of the present invention may comprise: a frame; and a thin film including a region in which carbon nanotubes are freestanding, formed on one surface of the frame.

[0012] According to one embodiment, the thin film comprises nanoparticles, and the nanoparticles may comprise one or more selected from the group consisting of cerium oxide (CeO2), manganese dioxide (MnO2), ruthenium oxide (RuO2), iron oxide (Fe3O4), titanium dioxide (TiO2), zinc oxide (ZnO), silver (Ag), platinum (Pt), gold (Au), copper (Cu), silicon (Si), graphene, activated carbon, and molybdenum disulfide (MoS2).

[0013] According to one embodiment, the thin film may include a three-dimensional network structure comprising a plurality of pores, and the nanoparticles may be dispersed in the network structure.

[0014] According to one embodiment, the thin film may have a thickness of 20 nm to 500 nm.

[0015] According to one embodiment, the thin film may exhibit a transmittance of 80% or more in the visible light region.

[0016] According to one embodiment, the thin film may exhibit a transmittance of 80% or more in the EUV region of a wavelength of 10 nm to 15 nm.

[0017] A method for manufacturing a carbon nanotube composite thin film including a freestanding region according to another embodiment may include the steps of: preparing a solution containing carbon nanotubes; filtering the solution; obtaining a carbon nanotube composite thin film; and forming the thin film on one side of an adhesive-free frame.

[0018] According to one embodiment, the step of preparing a solution containing carbon nanotubes; may further include the step of mixing nanoparticles into the solution.

[0019] According to one embodiment, the step of filtering the solution may be to filter the solution through a filter under vacuum conditions at a pressure of 1 kPa to 95 kPa.

[0020] According to one embodiment, the filter may comprise one or more selected from the group consisting of MCE (Mixed Cellulose Ester), PES (Polyethersulfone), PVDF (Hydrophilic Polyvinylidene Fluoride), CA (Cellulose Acetate), PTFE (Polytetrafluoroethylene), and Nylon.

[0021] According to one embodiment, the filter includes a first filter and a second filter, the pore size of the second filter is smaller than the pore size of the first filter, and the second filter may be stacked between a plurality of first filters.

[0022] According to one embodiment, the step of obtaining the carbon nanotube composite thin film may involve removing the filter using one or more selected from the group consisting of water, NMP, DMF, Acetone, DMSO, DMAc, MEK, and THF.

[0023] According to one embodiment, the step of obtaining the carbon nanotube composite thin film may be to physically remove the thin film by applying pressure to a filter. Effects of the invention

[0025] The present invention has the effect of being able to manufacture a carbon nanotube composite thin film including a freestanding region of an ultrathin film through a simplified manufacturing process.

[0026] In addition, the present invention has the effect of being able to control the electrical, mechanical, and optical properties of a carbon nanotube composite thin film and providing a method for attaching a frame without a separate adhesive.

[0027] However, the effects of the present invention are not limited to those described above, but include all effects naturally realized through the various configurations proposed in the present invention. Brief explanation of the drawing

[0029] FIG. 1 is a schematic diagram showing a carbon nanotube composite thin film including a freestanding region according to one embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a method for manufacturing a carbon nanotube composite thin film including a freestanding region according to one embodiment. Figure 3 is a schematic diagram showing the configuration of multiple filters. Figure 4 is an SEM image of a carbon nanotube and silver nanoparticle composite and a carbon nanotube composite thin film. Figure 5 is a TEM image of a carbon nanotube composite thin film. Figure 6 is an image of a carbon nanotube composite thin film formed on a frame. Figure 7 shows the results of evaluating the physical properties of a carbon nanotube composite thin film. Specific details for implementing the invention

[0030] The embodiments of the present invention are illustrative for the purpose of explaining the technical concept of the present invention. The scope of rights according to the present invention is not limited to the embodiments presented below or the specific description thereof.

[0031] All technical and scientific terms used in this invention, unless otherwise defined, have the meaning generally understood by those skilled in the art to which this invention pertains. All terms used in this invention are selected for the purpose of further explaining this invention and are not selected to limit the scope of rights according to this invention.

[0032] Expressions such as "comprising," "having," "having," etc. used in the present invention should be understood as open-ended terms implying the possibility of including other embodiments, unless otherwise stated in the phrase or sentence containing such expressions.

[0033] Unless otherwise stated, singular expressions described in the present invention may include the meaning of the plural form, and this applies likewise to singular expressions described in the claims.

[0035] A carbon nanotube composite film (100) including a freestanding region according to one embodiment of the present invention may include a frame (110); and a film (120) including a freestanding region of carbon nanotubes formed on one surface of the frame.

[0036] FIG. 1 is a schematic diagram showing a carbon nanotube composite thin film including a freestanding region according to one embodiment of the present invention.

[0037] The above frame has a hollow, and the carbon nanotube composite thin film may be formed on the frame to cover the hollow. The hollow is a portion where the substrate supporting the frame's skeleton and lower portion is not formed, and the area of ​​the thin film covering the hollow portion may be free-standing.

[0038] The hollow of the frame may occupy an area of ​​50% or more of the total area. Preferably, the hollow of the frame may occupy an area of ​​70% or more of the total area. More preferably, the hollow of the frame may occupy an area of ​​90% or more of the total area. As the area occupied by the hollow in the frame increases, the freestanding region of the carbon nanotube composite film may become wider, which may be desirable.

[0039] The above frame may comprise one or more materials selected from the group consisting of glass, Si, PP (Polypropylene), PE (Polyethylene), PET (Polyethylene terephthalate), resin, PMMA (Polymethyl methacrylate, acrylic), PC (Polycarbonate), PTFE (Polytetrafluoroethylene, Teflon), PES (Polyethersulfone), aluminum, stainless steel, and PI (Polyimide) film.

[0040] For example, the above frame may include PMMA with good processability or PTFE with excellent chemical resistance, but is not limited thereto.

[0042] According to one embodiment, the carbon nanotubes of the thin film may have an orientation aligned in one direction.

[0043] The carbon nanotubes may be multi-walled carbon nanotubes (MWCNT) and / or single-walled carbon nanotubes (SWCNT). Preferably, the thin film may comprise a plurality of single-walled carbon nanotubes (SWCNT).

[0044] The carbon nanotube composite thin film may contain 50% to 99% by weight of carbon nanotubes. If the thin film contains less than 50% by weight of carbon nanotubes, the durability of the thin film may decrease, and if it contains more than 99% by weight of carbon nanotubes, the functionality of the thin film may decrease. Preferably, the carbon nanotube composite thin film may contain 60% to 90% by weight of carbon nanotubes.

[0045] The carbon nanotube composite thin film of the present invention may exhibit an orientation in which a plurality of carbon nanotubes are aligned in one direction. Through the carbon nanotubes exhibiting said orientation, the thin film may exhibit enhanced optical, thermal, electrical, and mechanical properties.

[0046] The aforementioned thin film exhibiting directionality can have high transmittance for light of a specific polarization direction while effectively blocking light of other directions. This allows for increased exposure efficiency and transmittance in the EUV process, while minimizing unnecessary reflection or scattering.

[0047] Carbon nanotubes, which possess high thermal conductivity, can transfer heat more efficiently in the direction of heat flow when arranged in a unidirectionally aligned structure. Through this, the thin film can effectively dissipate the high heat generated during the EUV process, thereby minimizing deformation caused by thermal expansion. Furthermore, the electrical conductivity of the carbon nanotubes is enhanced through the aligned structure, allowing it to also provide antistatic functionality.

[0048] The orientation of the carbon nanotubes aligned in the aforementioned unidirectional manner can improve the mechanical strength, such as tensile strength and elastic modulus, of the thin film. This allows the thin film to maintain high durability even against minute external impacts.

[0050] The above carbon nanotubes can be combined with various functional nanoparticles to form a thin film.

[0051] According to one embodiment, the thin film comprises nanoparticles, and the nanoparticles may comprise one or more selected from the group consisting of cerium oxide (CeO2), manganese dioxide (MnO2), ruthenium oxide (RuO2), iron oxide (Fe3O4), titanium dioxide (TiO2), zinc oxide (ZnO), silver (Ag), platinum (Pt), gold (Au), copper (Cu), silicon (Si), graphene, activated carbon, and molybdenum disulfide (MoS2).

[0052] The above carbon nanotube composite thin film can improve the electrical, optical, and mechanical properties of the thin film by further including nanoparticles.

[0053] Since metal nanoparticles such as silver (Ag), platinum (Pt), gold (Au), and copper (Cu) inherently possess high electrical conductivity, denser conductive pathways can be formed when combined with the structure of unidirectionally aligned carbon nanotubes. These densely formed conductive pathways can increase the connectivity of electron transport pathways, thereby significantly improving the electrical conductivity of the thin film.

[0054] Carbon-based nanoparticles such as graphene and activated carbon exhibit high conductivity and strength similar to carbon nanotubes, so the in-plane conduction pathways become denser, which can further reduce sheet resistance and improve mechanical strength. Through activated carbon, it can also have an adsorption effect on organic gases and pollutants.

[0055] Metal oxide nanoparticles such as cerium oxide (CeO2), manganese dioxide (MnO2), ruthenium oxide (RuO2), iron oxide (Fe3O4), titanium dioxide (TiO2), and zinc oxide (ZnO) can suppress contamination and degradation in EUV irradiation environments through radical scavenging, redox buffering, etc.

[0056] Inorganic / layered nanoparticles such as silicon (Si) and molybdenum disulfide (MoS2) can act as mechanical and optical correction fillers within carbon nanotube networks.

[0057] The above nanoparticles can exhibit plasmon resonance phenomena by reacting with light of a specific wavelength, and can optimize the optical filtering effect of the thin film by minimizing light scattering and controlling reflection through synergistic effects with the anisotropic characteristics of carbon nanotubes. The above nanoparticles can enhance the thermal conductivity of the thin film to maximize the heat dissipation effect and contribute to maintaining structural stability even in high-temperature environments.

[0059] According to one embodiment, the thin film may include a three-dimensional network structure comprising a plurality of pores, and the nanoparticles may be dispersed in the network structure.

[0060] The thin film may include a microporous three-dimensional network structure formed of a plurality of carbon nanotubes, and the nanoparticles may be dispersed in the network structure to evenly improve the electrical, optical, and mechanical properties of the thin film.

[0061] Through nanoparticles dispersed in the network structure of the carbon nanotubes, load distribution at the nanoscale is effectively achieved, which can increase the mechanical strength of the thin film. The nanoparticles can reinforce the bonding strength of the thin film to improve tensile strength and elastic modulus, and can enhance durability by increasing wear resistance.

[0062] The above thin film can form a carbon nanotube composite thin film with high transmittance and improved electrical, thermal, and mechanical properties by enhancing physical properties through the orientation of unidirectionally aligned carbon nanotubes and the complex synergistic effect of nanoparticles.

[0063] Furthermore, the aforementioned synergistic effect can expand the possibilities for new functional thin films beyond simple improvement of physical properties. The synergy between carbon nanotubes and nanoparticles can maximize electromagnetic segregation effects and can also be utilized as a transparent electrode material requiring high conductivity and transparency. By utilizing the microporous structure of carbon nanotubes, the thin film can be used as a high-performance filter to screen out fine dust, harmful gases, and viruses, as well as a separation membrane for chemical separation processes in the chemical, environmental, and medical fields. Additionally, leveraging its ultra-thin properties, it can be used as a sensor capable of responding subtly to external vibrations.

[0065] According to one embodiment, the thin film may have a thickness of 20 nm to 500 nm.

[0066] The carbon nanotube composite thin film may have the characteristic of being formed with an ultrathin thickness. The thin film may have a thickness of 20 nm to 300 nm. Preferably, the thin film may be formed with a thickness of 20 nm to 75 nm. More preferably, the thin film may be formed with a thickness of 25 nm to 50 nm.

[0067] The above carbon nanotube composite thin film is formed with a thickness of 50 nm or less, thereby minimizing light scattering and absorption, which allows for very high transmittance, and reduces unnecessary reflection, which can be advantageously utilized in the EUV lithography process using a wavelength of 13.5 nm.

[0068] As the thickness of the thin film decreases, heat is rapidly dispersed, which is advantageous for preventing heat accumulation, and the pellicle containing the thin film can maintain stability even in a high-temperature environment.

[0069] The above carbon nanotube composite thin film can have the characteristic that excellent mechanical properties, such as the tensile strength of carbon nanotubes, are maintained even when formed with a fine thickness, and flexibility due to the thin thickness is added, thereby maintaining the durability of the thin film.

[0071] According to one embodiment, the thin film may exhibit a transmittance of 80% or more in the visible light region.

[0072] The thin film may exhibit a transmittance of 80% or more in the visible light region including wavelengths of 400 nm to 700 nm. Preferably, the thin film may exhibit a transmittance of 85% or more in the visible light region. For example, the thin film may exhibit a transmittance of 85% or more at a wavelength of 500 nm.

[0073] Since light scattering and haze are suppressed through unidirectionally aligned carbon nanotubes in the above thin film, the exposure time required to secure an effective amount of light reaching the wafer can be shortened. Pattern distortion can be minimized by suppressing phase irregularities within the optical path and flare caused by internal reflection through the orientation of the carbon nanotubes.

[0074] This reduces optical path distortion by minimizing the temperature rise and thermal expansion of the membrane, and allows heat to be efficiently dispersed through carbon nanotubes, thereby mitigating the concentration of thermal stress.

[0075] According to one embodiment, the thin film may exhibit a transmittance of 80% or more in the EUV region of a wavelength of 10 nm to 15 nm. Preferably, the thin film may exhibit a transmittance of 85% or more in a wavelength of 10 nm to 15 nm, and more preferably, a transmittance of 92% or more. As described above, due to the excellent transmittance of the thin film, the carbon nanotube composite thin film can be excellently utilized even in an EUV process utilizing a wavelength of 13.5 nm.

[0077] A method for manufacturing a carbon nanotube composite thin film including a freestanding region according to another embodiment may include the steps of: preparing a solution containing carbon nanotubes; filtering the solution; obtaining a carbon nanotube composite thin film; and forming the thin film on one side of an adhesive-free frame.

[0078] FIG. 2 is a schematic diagram illustrating a method for manufacturing a carbon nanotube composite thin film including a freestanding region according to one embodiment.

[0079] The method for manufacturing a carbon nanotube composite thin film is described below. The description of the components of the carbon nanotube composite thin film is as described above.

[0080] The step of preparing a solution containing the carbon nanotubes may involve dispersing single-walled carbon nanotubes and / or multi-walled carbon nanotubes in a solvent.

[0081] The above solvent may include one or more selected from the group consisting of IPA (Isopropyl Alcohol), NMP (1-Methyl-2-Pyrrolidone), alcohol, polar organic solvents, and non-polar organic solvents. In the present invention, the type of solvent is not particularly limited, and any solvent capable of evenly dispersing carbon nanotubes may be used.

[0082] Surfactants can be used as dispersants, and cationic, anionic, and nonionic surfactants can be used. The type of dispersant is not particularly limited, and as an example, the dispersant may be Triton or SDS (Sodium Dodecyl Sulfate).

[0083] The carbon nanotubes may be included in the solvent in an amount of 0.001% to 5% by weight. The thickness of the carbon nanotube composite film can be controlled by adjusting the weight percentage of the carbon nanotubes. The weight percentage of the carbon nanotubes can be adjusted according to the thickness of the target film to be fabricated.

[0084] According to one embodiment, the step of preparing a solution containing carbon nanotubes; may further include the step of mixing nanoparticles into the solution.

[0085] To control the electrical, thermal, and mechanical properties of a carbon nanotube composite thin film, nanoparticles can be mixed into a solution in which carbon nanotubes are dispersed. The nanoparticles may include one or more selected from the group consisting of cerium oxide (CeO2), manganese dioxide (MnO2), ruthenium oxide (RuO2), iron oxide (Fe3O4), titanium dioxide (TiO2), zinc oxide (ZnO), silver (Ag), platinum (Pt), gold (Au), copper (Cu), silicon (Si), graphene, activated carbon, and molybdenum disulfide (MoS2).

[0086] The above nanoparticles may have a diameter of 1 nm to 400 nm, but are not limited thereto.

[0087] The above nanoparticles may be included in the solution in an amount of 0.1 volume% to 10 volume%. If the nanoparticles are included in an amount of less than 0.1 volume%, the effect intended to be achieved through the nanoparticles may not be sufficiently exhibited, and if they are included in an amount exceeding 10 volume%, haze and scattering may increase, and aggregation or microdefects may occur. Preferably, the nanoparticles may be included in the solution in an amount of 0.1 volume% to 5 volume%, and more preferably, in an amount of 0.1 volume% to 2 volume%.

[0088] The weight of the nanoparticles may be included in an amount of 1% to 40% of the weight of the carbon nanotubes. If the weight of the nanoparticles is included in an amount of less than 1% of the weight of the carbon nanotubes, the bonding may be insufficient and the improvement in sheet resistance may be minimal, and if it is included in an amount exceeding 40%, the haze may increase and sufficient transmittance may not be secured. Preferably, the weight of the nanoparticles may be included in an amount of 5% to 30% of the weight of the carbon nanotubes.

[0090] According to one embodiment, the step of filtering the solution may be to filter the solution through a filter under vacuum conditions at a pressure of 1 kPa to 95 kPa.

[0091] The carbon nanotube composite thin film of the present invention is characterized by being obtained by filtering a solution in which carbon nanotubes are dispersed through a filter under vacuum. Unlike conventional techniques that require complex processes to manufacture carbon nanotube composite thin films, this invention offers an advantage in that it can manufacture a uniform, ultrathin carbon nanotube composite thin film through a relatively simple process.

[0092] The above solution can be filtered at a pressure of 0 kPa to 100 kPa. If the pressure exceeds 100 kPa, the filter may be damaged, making it difficult to obtain a carbon nanotube composite thin film. The pressure can be appropriately controlled to suit the desired thickness of the thin film and its use.

[0093] The filter is positioned on a ceramic support, and the ceramic support can serve to support the filter. The ceramic support has a pore size larger than that of the filter and may have a pore size of 20 μm to 50 μm.

[0094] According to one embodiment, the filter may comprise one or more selected from the group consisting of MCE (Mixed Cellulose Ester), PES (Polyethersulfone), PVDF (Hydrophilic Polyvinylidene Fluoride), CA (Cellulose Acetate), PTFE (Polytetrafluoroethylene), and Nylon.

[0095] After the above vacuum filtration, a carbon nanotube composite thin film may be formed on the filter. The pore size of the filter may be 0.1 μm to 5 μm.

[0096] The characteristics of the carbon nanotube composite thin film manufactured may vary depending on the pore size and material of the filter. Therefore, by using multiple filters in combination, the characteristics of the carbon nanotube composite thin film can be adjusted to meet specific needs.

[0097] According to one embodiment, the filter includes a first filter (210) and a second filter (220), the pore size of the second filter is smaller than the pore size of the first filter, and the second filter may be stacked between a plurality of first filters.

[0098] Figure 3 is a schematic diagram showing the configuration of multiple filters.

[0099] To form a thin film of more uniform thickness, multiple filters with different pore sizes can be utilized. Additionally, multiple filters with different pore sizes can be stacked and utilized.

[0100] For example, the filter may consist of five stacked filters, and the first filter may be included more than the second filter among the five filters. For example, three first filters may be stacked on the lower surface, a second filter may be stacked on top of them, and a first filter may be stacked on top of them. The first filter may have a pore size of 3 μm to 5 μm, and the second filter may have a pore size of 0.1 μm to 1 μm.

[0101] The first filter on the uppermost surface can serve as a pre-filter to remove impurities or contaminants contained in the solution containing the carbon nanotubes. The second filter formed below it can be a core filter on which a carbon nanotube composite film is formed. Since the second filter has a smaller pore size than the first filter, a carbon nanotube composite film can be formed on the second filter. The three first filters below the second filter can serve as averaging filters to uniformly distribute the pressure applied to the filters.

[0102] The pore size of the first filter may be 5 to 100 times larger than the pore size of the second filter. Due to the difference in pore sizes between the first filter and the second filter, the first filter can perform the role of removing impurities and dispersing pressure, and a carbon nanotube composite film may be formed on the second filter having a relatively small pore size. Preferably, the pore size of the first filter may be 5 to 50 times larger than the pore size of the second filter. For example, the pore size of the first filter may be 5 μm and the pore size of the second filter may be 0.2 μm, but is not limited thereto.

[0103] For example, the step of filtering the solution may further include a step of controlling the orientation of the carbon nanotubes. The orientation of the carbon nanotubes may be controlled by controlling the fluid flow or the potential difference of the electrodes, but is not limited thereto.

[0105] According to one embodiment, the step of obtaining the carbon nanotube composite thin film may involve removing the filter using one or more selected from the group consisting of water, NMP, DMF, Acetone, DMSO, DMAc, MEK, and THF.

[0106] After drying the carbon nanotube composite thin film formed on the filter through the above vacuum filtration, the filter can be separated to obtain the carbon nanotube composite thin film.

[0107] The carbon nanotube composite thin film and filter described above may be obtained by immersing the filter in an organic solvent capable of dissolving only the filter. The organic solvent may be one or more selected from the group consisting of water, NMP, DMF, acetone, DMSO, DMAc, MEK, and THF. For example, an MCE filter may be soluble in NMP, DMF, DMSO, and acetone. A PES filter may be soluble in DMSO, DMF, and NMP. By using an appropriate organic solvent depending on the filter used to dissolve only the filter, a carbon nanotube composite thin film can be obtained more simply than with conventional techniques.

[0108] The carbon nanotube composite film formed on the filter can effectively dissolve the filter by immersing it in the organic solvent in a direction in which the filter first comes into contact with the organic solvent. For example, the lower surface of the filter may be immersed in the organic solvent so that a large surface area of ​​the filter can simultaneously come into contact with the organic solvent. Rapidly dissolving a large surface area of ​​the filter in the organic solvent may be desirable as it prevents the filter from remaining on the film.

[0109] The carbon nanotube composite film and filter may be obtained by immersing the film in water. Since the surface of the filter exhibits hydrophobic properties, it can naturally separate from the film when immersed in water. Preferably, the water may be distilled water (DI water). Separation of the filter using water may be effective when the thickness of the carbon nanotube composite film is 2 μm or more.

[0110] The step of obtaining the carbon nanotube composite thin film can be repeated multiple times as needed.

[0111] According to one embodiment, the step of obtaining the carbon nanotube composite thin film may be to physically remove the thin film by applying pressure to a filter.

[0112] The carbon nanotube composite thin film described above may be formed by applying a positive pressure opposite to the pressure applied when filtering a solution containing carbon nanotubes. In the filtration step, pressure is applied from the filter toward the ceramic support, whereas the positive pressure may be applied from the ceramic support toward the filter. Due to this pressure, the carbon nanotube composite thin film formed on the filter can be mechanically separated from the filter. By adjusting the direction of the applied pressure differently as described above, the carbon nanotube composite thin film can be obtained more simply.

[0114] According to one embodiment, the method may further include the step of obtaining the carbon nanotube composite thin film; and subsequently, the step of forming the thin film on one side of an adhesive-free frame.

[0115] A carbon nanotube composite thin film obtained as described above can be transferred onto a frame to form a freestanding carbon nanotube composite thin film. The frame may include one or more selected from the group consisting of glass, silicon, PP (Polypropylene), PE (Polyethylene), PET (Polyethylene terephthalate), resin, and PI (Polyimide) film, but is not limited thereto.

[0116] The step of forming on one side of the above frame can be performed by utilizing various transfer techniques, such as removing the solution while approaching the frame at an angle between 0 and 90 degrees or placing a thin film on the frame.

[0117] The carbon nanotube composite thin film described above can be attached to a frame without a separate adhesive because shrinkage and tensile stress occur as the film dries after being placed on the frame. Since an adhesive process is unnecessary, factory convenience is improved, and reliability can be enhanced by preventing problems such as contamination and reduced transmittance caused by adhesives.

[0118] The carbon nanotube composite thin film formed on one side of the above frame may further undergo the step of removing residual solvent and drying.

[0119] The above method for manufacturing a carbon nanotube composite thin film can obtain a self-supporting carbon nanotube composite thin film using only a wet process without undergoing complex semiconductor processes such as photolithography, etching, and patterning, and can reduce the burden of building expensive equipment and facilities, and lower manufacturing costs by significantly simplifying process steps. Therefore, compared to conventional technology, it can have the advantage of shortening the process time and reducing the burden of equipment maintenance and management.

[0120] In addition, since self-supporting carbon nanotube composite thin films can be obtained using only vacuum filtration and filter removal processes, it is possible to fabricate uniform ultrathin films over a wide area and mass-produce them.

[0122] The present invention will be explained in more detail through the following examples. However, these examples represent some experimental methods and configurations to illustrate the invention, and the scope of the invention is not limited to these examples.

[0124] Preparation Example: Preparation of a carbon nanotube composite thin film

[0125] 0.4 wt% of Baterial SWCNT and 0.2 wt% of Seohyun Tech SWCNT were dispersed and diluted in a water solvent. Subsequently, to achieve more complete dispersion, undispersed CNTs were removed by centrifugation at a gravitational acceleration between 100 g and 3000 g for 1 to 20 minutes, and only the supernatant was collected and used. Then, Ag nanoparticles were dispersed to prepare a solution. A five-layer stacked filter was prepared by stacking MCE (5 µm) and MCE (0.2 µm) and adding three MCE (5 µm) layers to the bottom. Subsequently, the solution containing carbon nanotubes was vacuum filtered at a pressure of 80 kPa.

[0126] An MCE (0.2㎛) filter was placed in a high-boiling point polar aprotic solvent such as DMSO to dissolve the filter, and then the same solvent was added for dilution and exchange to remove residues. Subsequently, the filter was transferred onto a frame in the solvent and dried at room temperature or in an oven at 30-100 degrees for 5 hours to produce a carbon nanotube composite thin film.

[0128] Example 1: Evaluation of Filter and Manufacturing Method

[0129] Various filters and manufacturing methods were compared while manufacturing carbon nanotube composite thin films as in the above manufacturing example. The best result was ○○○, and the results are indicated by rank below.

[0132] Filter material Surface quality Delamination MCE ○○○ ○○ PES ○○○ ○○ PVDF ○○○ ○ CA ○ x PTFE-H ○ x PTFE-D ○ x NYLON ○ x

[0133] Thickness control Thickness uniformity Transferability Size Spin coating ○○ ○○ ○○ ○○○ Spray coating ○ ○ ○○ ○○○ Vacuum filtration ○○○ ○○○ ○○ ○○

[0135] Through the above results, it was confirmed that MCE and PES are the most suitable filters, and that vacuum filters are more suitable than spin coating and spray coating.

[0137] Example 2: Characterization of Carbon Nanotube Composite Thin Films

[0138] To evaluate the characteristics of the carbon nanotube composite thin film of the prepared example, images were taken using a transmission electron microscope (TEM) and compared.

[0139] Figure 4 is an SEM image of a carbon nanotube composite thin film.

[0140] SEM images of a carbon nanotube composite thin film (a) manufactured by the wet process of the present invention using carbon nanotubes with a diameter of 2 nm to 30 nm and an EUV pellicle (b) manufactured by a conventional drying process were compared. The EUV pellicle manufactured by the conventional drying process exhibits a typical porous morphology at a thickness of 30 nm to 50 nm, and a surface roughness R a The (surface roughness value) was less than 10nm, which is a typical value.

[0141] The carbon nanotube composite thin film prepared by the wet process of the present invention exhibited high porosity and an interconnected network morphology at a thickness of 40 nm, and surface roughness R a It was confirmed that it has a smoother surface, with a thickness of approximately 2.3 nm and a maximum of 4 nm.

[0142] Figure 5 is a TEM image of a carbon nanotube composite thin film.

[0143] The concentration of iron (Fe) contained in the EUV pellicle produced through the drying process was 1.6 at% to 1.9 at%, and the Fe catalyst was confirmed in the TEM image (b). On the other hand, the concentration of iron (Fe) contained in the carbon nanotube composite thin film produced through the wet process of the present invention was about 0.11 at% or less, and the Fe catalyst was not confirmed in the TEM image, and it was confirmed that the thin film was much more purified (a).

[0144] Figure 6 is an image of a carbon nanotube composite thin film formed on a frame.

[0145] Carbon nanotube composite thin films of various thicknesses were prepared through the above preparation examples (Fig. 6 (a): 40 nm, (b): 300 nm, (c): 800 nm, (d): 3 µm, (e): 10 µm). It was confirmed that the transmittance increases as the thickness of the carbon nanotube composite thin film decreases. Through this, it was confirmed that a carbon nanotube composite thin film with a thickness of 40 nm can be obtained.

[0147] Wavelength (㎛) Transmittance (%) Wavelength (㎛) Transmittance (%) 700 87.7403 550 86.2952 690 87.6535 540 86.1249 680 87.5906 530 85.9729 670 87.4744 520 85.7539 660 87.4058 510 85.5395 650 87.3377 500 85.3218 640 87.2405 490 85.0553 630 87.1335 480 84.7795 620 87.0105 470 84.4896 610 86.9387 460 84.1757 600 86.8722 450 83.8361 590 86.7678 440 83.4996 580 86.6384 430 83.0822 570 86.5526 420 82.6398 560 86.4308 410 82.1352 550 86.2952 400 81.6012

[0149] Table 3 shows the results of measuring the transmittance in the visible light region of a carbon nanotube composite thin film with a thickness of 50 nm. It was confirmed that the transmittance in the visible light region was 81% or higher and the maximum transmittance was 87% or higher. Through this, it was confirmed that the transmittance of the carbon nanotube composite thin film is high in the visible light wavelength region.

[0150] Figure 7 shows the results of evaluating the physical properties of a carbon nanotube composite thin film.

[0151] To evaluate the mechanical properties of the carbon nanotube composite thin film, a composite thin film with a thickness of 800 nm was used.

[0152] Vibrations were induced in the aforementioned thin film by applying sound excitation (a 50–10,000 Hz sweep signal for 1 second), and displacement data for 1 second was measured using a displacement sensor located at the center of the thin film. These measured data were converted to the frequency domain using FFT, and peak frequencies were extracted from the frequency data to confirm that the peak intervals were constant. Since the constant peak intervals were multiples of the main vibration mode, the data was used to define the main vibration mode. The relationships between initial stress, density, and frequency according to the vibration mode were predicted using known formulas. Through this, it was mathematically confirmed that f increases linearly as the frequency of the main vibration mode (vibration mode m=n=1) increases. Using the red curve fitting, the predicted initial stress (Estimated σ0) was calculated as Density (ρ) = 300 kg / m³. 3 It was confirmed that it was 1026 Pa when measured.

[0154] The foregoing description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations within the scope of the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are intended to explain, not limit, the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by these embodiments. The scope of protection of the present invention shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention.

Claims

Claim 1 A carbon nanotube composite thin film comprising a frame; and a thin film comprising a freestanding region formed on one surface of the frame. Claim 2 A carbon nanotube composite thin film comprising a freestanding region, wherein the thin film comprises nanoparticles, and the nanoparticles comprise one or more selected from the group consisting of cerium oxide (CeO2), manganese dioxide (MnO2), ruthenium oxide (RuO2), iron oxide (Fe3O4), titanium dioxide (TiO2), zinc oxide (ZnO), silver (Ag), platinum (Pt), gold (Au), copper (Cu), silicon (Si), graphene, activated carbon, and molybdenum disulfide (MoS2). Claim 3 A carbon nanotube composite thin film comprising a freestanding region, wherein, in paragraph 2, the thin film comprises a three-dimensional network structure including a plurality of pores, and the nanoparticles are dispersed in the network structure. Claim 4 A carbon nanotube composite thin film comprising a freestanding region, wherein the thin film has a thickness of 20 nm to 500 nm in claim 1. Claim 5 A carbon nanotube composite thin film including a freestanding region, wherein the thin film exhibits a transmittance of 80% or more in the visible light region in claim 1. Claim 6 A carbon nanotube composite thin film including a freestanding region, wherein the thin film exhibits a transmittance of 80% or more in the EUV region of a wavelength of 10 nm to 15 nm in claim 1. Claim 7 A method for manufacturing a carbon nanotube composite thin film including a freestanding region, comprising the steps of: preparing a solution containing carbon nanotubes; filtering the solution; obtaining a carbon nanotube composite thin film; and forming the thin film on one side of an adhesive-free frame. Claim 8 A method for manufacturing a carbon nanotube composite thin film including a freestanding region, wherein, in claim 7, the step of preparing a solution containing carbon nanotubes; further comprises the step of mixing nanoparticles into the solution. Claim 9 A method for manufacturing a carbon nanotube composite thin film comprising a freestanding region, wherein, in claim 7, the step of filtering the solution; is to filter the solution through a filter under vacuum conditions at a pressure of 1 kPa to 95 kPa. Claim 10 A method for manufacturing a carbon nanotube composite thin film including a freestanding region, wherein, in claim 9, the filter comprises one or more selected from the group consisting of MCE (Mixed Cellulose Ester), PES (Polyethersulfone), PVDF (Hydrophilic Polyvinylidene Fluoride), CA (Cellulose Acetate), PTFE (Polytetrafluoroethylene), and Nylon. Claim 11 A method for manufacturing a carbon nanotube composite thin film including a freestanding region, wherein, in claim 9, the filter comprises a first filter and a second filter, the pore size of the second filter is smaller than the pore size of the first filter, and the second filter is stacked between a plurality of first filters. Claim 12 A method for manufacturing a carbon nanotube composite thin film comprising a freestanding region, wherein the step of obtaining the carbon nanotube composite thin film in claim 7; is to remove the filter using one or more selected from the group consisting of water, NMP, DMF, Acetone, DMSO, DMAc, MEK, and THF. Claim 13 A method for manufacturing a carbon nanotube composite thin film comprising a freestanding region, wherein the step of obtaining the carbon nanotube composite thin film in claim 7 is to physically remove the thin film by applying pressure to a filter.

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