Pellicle structure for EUV lithography and methods of manufacturing thereof

Abstract

One method for forming a protective film includes growing carbon nanotubes (CNTs), coating the CNTs with one or more nanotubes made of different materials, and removing the CNTs. The CNTs can be grown over a filter, which can then be removed. The CNTs can be in contact with a frame. Different materials include one or more of boron nitride, hexagonal boron nitride (h-BN), SiC, MoS2, MoSe2, WS2, WSe2, SnS2, SnS, ZrO2, ZrO, and TiO2.

Description

[Technical Field]

[0001] None [Previous Technology]

[0002] A protective film is a thin, transparent film stretched over a frame and bonded to the photomask to protect it from damage, dust, and / or moisture. In extreme ultraviolet (EUV) lithography, a protective film with high transparency, high mechanical strength, and low or no contamination in the EUV wavelength region is generally applied. [Summary of the Invention]

[0003] None

Implementation Method

[0005] It should be understood that the following disclosure provides many different embodiments or instances for implementing various features of this disclosure. Specific examples of components and configurations are described below to simplify this disclosure. Of course, these are merely examples and are not intended to be limiting. For example, the dimensions of an element are not limited to the range or values ​​disclosed, but may depend on process conditions and / or the required nature of the apparatus. Furthermore, the formation of a first feature above or on a second feature in the following description may include embodiments where the first and second features are formed in direct contact, and may also include embodiments where additional features may be formed to be inserted between the first and second features such that the first and second features are not in direct contact. For simplicity and clarity, various features are drawn arbitrarily at different scales. In the accompanying drawings, some layers / features are omitted for simplicity.

[0006] Furthermore, for ease of description, spatial relative terms such as "below," "under," "lower," "above," "upper," and the like may be used herein to describe the relationship between one element or feature illustrated in the figures and another element(s) or feature(s). Spatial relative terms are intended to cover different orientations of the device during use or operation, other than those depicted in the figures. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein may be interpreted similarly accordingly. Furthermore, the term "made of" may mean "comprising" or "consisting of." Additionally, in the following manufacturing processes, there may be one or more additional operations between the operations, and the order of operations may vary. In this disclosure, the phrase "at least one of A, B, and C" means any one of A, B, C, A+B, A+C, B+C, or A+B+C, and unless otherwise stated, does not mean that it comes from A, from B, and from C. The materials, configurations, structures, operations, and / or dimensions explained by one embodiment can be applied to other embodiments, and their detailed descriptions may be omitted.

[0007] EUV lithography is one of the key technologies for extending Mohr's Law. However, due to the scaling down of the wavelength from 193 nm (ArF) to 13.5 nm, the EUV light source suffers strong power attenuation due to environmental adsorption. Even if the stepper / scanner chamber operates under vacuum to prevent strong gas adsorption of EUV, maintaining high EUV transmittance of the EUV light source to the wafer remains an important factor in EUV lithography.

[0008] Protective films generally require high transparency and low reflectivity. In ultraviolet (UV) or deep UV (DUV) lithography, the protective film is made of a transparent resin film. However, in EUV lithography, resin-based films are unacceptable, and in some embodiments, non-organic materials such as polycrystalline silicon, silicates, or metal films are used.

[0009] One of the bottlenecks in EUV production performance is the failure of the EUV shielding film, such as deformation, cracking, and breakage.

[0010] Carbon nanotubes (CNTs) are among the materials suitable for protective films used in EUV photomasks because CNTs have a high EUV transmittance of over 96.5%. Generally, protective films used in EUV reflective shields need the following properties: (1) long lifetime in the hydrogen-rich radical operating environment of EUV steppers / scanners; (2) strong mechanical strength to minimize sagging during vacuum pumping and degassing operations; (3) high or perfect blocking properties for particles larger than about 20 nm (killer particles); and (4) good heat dissipation to prevent the protective film from burning out due to EUV radiation.

[0011] However, strong CNT-sp2 bonds are easily etched by EUV-induced hydrogen and oxygen plasma in an EUV scanner environment. The protective coating for CNTs includes amorphous films. However, amorphous films are also easily etched in an EUV scanner environment, which reduces the usefulness of the protective coating. CNT non-uniformity can also be a problem. Non-uniformity can lead to poor patterning due to differences in EUVT (EUV transmittance) and / or EUVR (EUV reflectance).

[0012] Furthermore, the temperature of the protective film increases with increasing EUV power. For example, when the EUV power is 436±20 W, the temperature of the protective film can be in the range of 527±50°C. Since the CNT protective film is only thermally stable in the range of approximately 500 to 700°C, it may not be able to withstand such high temperatures.

[0013] Particles formed from inorganic materials other than elemental carbon-based materials or ceramics can operate at higher temperatures because they are thermally stable at temperatures up to about 800 to 900°C. Protective films formed from inorganic or ceramic materials (such as boron nitride nanotubes (BNNTs)) have higher thermal stability than protective films formed from CNTs.

[0014] Some inorganic or ceramic nanotube deposition methods produce short and poor-quality nanotubes, making it difficult to form independent protective films. However, this disclosure discloses a method for providing high-transmittance, high-strength EUV protective films. According to some embodiments of this disclosure, single-walled or double-walled carbon nanotubes (CNTs) are used to form independent protective films as templates. Then, inorganic or ceramic nanotubes made of a different material than the carbon nanotubes are wrapped around the carbon nanotubes, thereby creating a core-shell structure. After the shell structure is formed, the CNTs can be partially or completely removed by heating.

[0015] In some embodiments of this disclosure, the nanotube system has a one-dimensional elongated tube with a diameter ranging from about 0.5 nm to about 100 nm.

[0016] In this disclosure, the protective film for an EUV photomask comprises a network film having a plurality of nanotubes forming a grid structure. Furthermore, a method for producing a protective film with increased mechanical strength and increased EUV transmittance is also disclosed.

[0017] Figures 1A and 1B show an EUV shielding film 10 according to an embodiment of the present disclosure. In some embodiments, the shielding film 10 for EUV reflective shielding includes a main mesh film 100 disposed above and attached to a shielding film frame 15. In some embodiments, the main mesh film 100 is a transparent film that is transparent to electromagnetic radiation (such as EUV radiation). In some embodiments, the transparent film 100 has an EUV transmittance greater than 96.5%. The transparent film 100 is opaque to some electromagnetic wavelengths (such as infrared or visible light radiation) and transparent to other electromagnetic wavelengths (such as EUV radiation or X-ray radiation). In some embodiments, as shown in Figure 1A, the main mesh film 100 includes a plurality of nanotubes 20, such as single-walled nanotubes 20S, while in other embodiments, as shown in Figure 1B, the nanotubes 20 constituting the main mesh film 100 include a plurality of multi-walled nanotubes 20M. In some embodiments, the single-walled nanotubes are non-elemental carbon-based nanotubes. In some embodiments, the non-elemental carbon-based material includes at least one of boron nitride (BN) (including hexagonal boron nitride (h-BN)), SiC, or transition metal dichalcogenides (TMD) (denoted by MX2, where M = Mo, W, Pd, Pt, Sn, and / or Hf, and X = S, Se, and / or Te). In some embodiments, TMD is one of MoS2, MoSe2, WS2, or WSe2. In other embodiments, the non-elemental carbon-based material is an inorganic material or a ceramic. In some embodiments, the inorganic material includes at least one of SnS, ZrO2, ZrO, or TiO2.

[0018] In some embodiments, nanotubes are joined or attached to each other to form a nanotube bundle.

[0019] In some embodiments, multi-walled nanotubes are coaxial nanotubes having one or more walls coaxially surrounding one or more inner tubes. In some embodiments, the main network membrane 100 comprises only one type of nanotube (e.g., single-walled, multi-walled, or single-material), while in other embodiments, different types of nanotubes form the main network membrane 100. In some embodiments, the multi-walled nanotubes are multi-walled inorganic or ceramic nanotubes. In some embodiments, some of the multi-walled nanotubes form a bundle of nanotubes attached to each other.

[0020] In some embodiments, the sheath (support) frame or boundary 15 is attached to the main mesh film 100 to maintain space between the main mesh film of the sheath and the EUV mask (pattern area) when mounted on an EUV mask. The sheath frame 15 of the sheath is attached to the surface of the EUV mask with a suitable bonding material. In some embodiments, the bonding material is an adhesive, such as acrylic or silicone adhesive or a cross-linked adhesive. The dimensions of the frame structure are larger than the area of ​​the black border of the EUV mask, such that the sheath covers not only the circuit pattern area of ​​the mask but also the black border.

[0021] Figures 2A, 2B, 2C, and 2D show various views of a multi-walled nanotube according to an embodiment of the present disclosure.

[0022] In some embodiments, the nanotubes in the main network membrane 100 include multi-walled nanotubes, also known as coaxial nanotubes. Figure 2A shows a perspective view of a multi-walled coaxial nanotube having three tubes 210, 220, and 230, and Figure 2B shows a cross-sectional view thereof. In some embodiments, the inner tube 210 and the outer tubes 220 and 230 are non-carbon-based nanotubes, such as boron nitride nanotubes.

[0023] The number of tubes in a multi-walled nanotube is not limited to three. In some embodiments, the multi-walled nanotube has two coaxial nanotubes, as shown in Figure 2C. In other embodiments, the multi-walled nanotube includes an innermost tube 210 and first to Nth nanotubes, including an outermost tube 200N, where N is a natural number from 1 to about 30, as shown in Figure 2D. In some embodiments, N ranges from 3 to 20, and in other embodiments, from 5 to 10. In some embodiments, at least one of the first to Nth outer layers is a nanotube coaxially surrounding the innermost nanotube 210. In some embodiments, the innermost tube 210 and all of the first to Nth outer layers are non-carbon-based nanotubes. In other embodiments, one or more of the tubes are carbon-based nanotubes.

[0024] In some embodiments, the diameter of the innermost nanotube ranges from about 0.5 nm to about 20 nm, in other embodiments from about 1 nm to about 10 nm, and in still other embodiments from about 2 nm to about 5 nm. In some embodiments, the diameter of the multi-walled nanotube (i.e., the diameter of the outermost tube) ranges from about 3 nm to about 40 nm, and in other embodiments from about 5 nm to about 20 nm. In some embodiments, the length of the multi-walled nanotube ranges from about 0.5 μm to about 50 μm, and in other embodiments from about 1.0 μm to about 20 μm.

[0025] Figures 3A, 3B and 3C show a method for manufacturing a nano-network membrane for a protective film according to an embodiment of the present disclosure.

[0026] In some embodiments, the carbon nanotube (CNT) 90 is formed by a chemical vapor deposition (CVD) process. In some embodiments, the synthesized nanotube is deposited on a support film 80 by performing a CVD process using a vertical furnace as shown in Figure 3A, as shown in Figure 3B. The network film 100 formed above the support film 80 is then detached from the support film 80 and transferred to a protective film frame 15, as shown in Figure 3C.

[0027] In the embodiment shown in Figure 3A, a floating catalyst CVD process is used to form carbon nanotubes (CNTs). In some embodiments, a funnel-shaped quartz reactor 300 is used to form CNTs 90. The reactor 300 includes a tubular quartz wall 310. The upper portion of the quartz tube is cylindrical, and the lower portion is conical. The quartz tube wall is surrounded by a heater 320. The nanotubes 90 are deposited on a filter or support membrane 80. In some embodiments, a stage or shield 330 on which the support membrane 80 is disposed rotates continuously or intermittently (stepwise), such that the synthesized nanotubes are deposited on the support membrane 80 in different or random orientations. In some embodiments, the membrane support is filter paper. In some embodiments, the shield 330 is a plate that inhibits CNT penetration of the support membrane 80. In some embodiments, CNTs can penetrate the filter in the unshielded area of ​​the support membrane 80.

[0028] In some embodiments, the funnel-shaped quartz reactor has a diameter ranging from about 1 cm to about 100 cm in the upper cylindrical portion, tapering to about 1 mm to about 10 cm at the end of the lower conical portion. In some embodiments, the reactor has a height H1 ranging from about 200 cm to about 600 cm, and the tapered portion of the lower conical portion has a height H2 ranging from about 10 cm to about 100 cm. In some embodiments, the cone angle θ of the lower conical portion ranges from about 100º to about 150º.

[0029] To produce CNT 90, a carbon source is introduced into reactor inlet 340 along with a catalyst. In some embodiments, a sulfur compound is also introduced into reactor inlet 340. In some embodiments, the carbon source comprises one or more hydrocarbon gases, including methane with a flow rate ranging from greater than 0 sccm to about 800 sccm, and ethane with a flow rate ranging from greater than 0 sccm to about 900 sccm. In some embodiments, the carbon source is introduced at a flow rate of about 4 sccm to about 200 sccm. In some embodiments, the catalyst may be any suitable catalyst, such as iron or iron-containing catalysts, including ferrocene (Fe(C5H5)2); and transition metal carbonyl complexes, including M(CO)x, wherein M is a transition metal, such as Cr, Mo, or W, and in some embodiments, x ranges from 3 to 10. Other suitable catalysts include CoFe, Co, CoNi, Ni, CoMo, and FeMo. In some embodiments, the catalyst is introduced into the reactor at a flow rate ranging from greater than 0 sccm to about 1 sccm. In some embodiments, a sulfur-containing compound is introduced into the reactor. The sulfur-containing compound is one or more of hydrogen sulfide and thiophene. The sulfur-containing compound is introduced into the reactor at a flow rate ranging from greater than 0 sccm to about 1 sccm. Hydrogen and a carrier gas are introduced into the reactor through gas inlet 350. The carrier gas includes one or more of argon, nitrogen, and oxygen. Hydrogen is introduced into the reactor at a flow rate ranging from greater than 0 sccm to about 1000 sccm. The carrier gas may be introduced into the reactor at the following flow rates: argon - about 0 to about 50000 sccm; nitrogen - about 0 sccm to about 60000 sccm; oxygen - about 0 to about 1 sccm.

[0030] In some embodiments, during the CNT growth operation, the reactor is heated to a temperature of approximately 300°C to approximately 1100°C. In some embodiments, a temperature gradient 370 is maintained along the height of the reactor. For example, in some embodiments, the temperature increases from the top of the reactor toward the bottom of the reactor, or vice versa. In some embodiments, the temperature increases along the gradient from approximately 300°C to approximately 1100°C. In some embodiments, the mask or stage 330 rotates at a rate of approximately 0 rpm to approximately 500 rpm. In some embodiments, a vacuum 360 is evacuated during the nanotube growth operation to provide uniform CNT dispersion. In some embodiments, the growth operation lasts for a sufficient period of time to obtain a nanotube network layer of the desired thickness.

[0031] Figure 4 illustrates another method for manufacturing a network film of nanotubes according to an embodiment of the present disclosure. As previously described, in some embodiments, the nanotubes are formed by a CVD method. In some embodiments, the nanotubes are formed by various other methods, such as arc discharge or laser ablation methods. The nanotubes are then dispersed in a solution. The solution includes a solvent, such as water or an organic solvent; and a surfactant, such as sodium dodecyl sulfate (SDS).

[0032] As shown in Figure 4, the support membrane or filter 80 is placed between the chamber or cylinder containing the nanotube dispersion solution and the vacuum chamber. In some embodiments, the support membrane is an organic or inorganic porous or mesh material. In some embodiments, the support membrane is a woven or nonwoven fabric. In some embodiments, the support membrane has a circular shape, in which a 150 mm × 150 mm square (EUV shield size) protective membrane can be placed.

[0033] As shown in Figure 4, the pressure in the vacuum chamber decreases, thereby pressurizing the solvent in the chamber or cylinder. Since the mesh or pore size of the support membrane or filter is much smaller than the size of the nanotubes, the nanotubes 90 are captured by the support membrane as the solvent passes through it. The support membrane on which the nanotubes are deposited is removed from the filter element and dried. In some embodiments, the filtration deposition is repeated to obtain a nanotube network layer of the desired thickness. In some embodiments, after depositing nanotubes in solution, other nanotubes are dispersed in the same or a new solution, and the filtration deposition is repeated. In other embodiments, another filtration deposition is performed after the nanotubes are dried. In the repetitions, in some embodiments, the same type of nanotubes are used, while in other embodiments, different types of nanotubes are used. In some embodiments, the nanotubes dispersed in the solution include multi-walled nanotubes.

[0034] Figures 5A and 5B, and Figures 6A and 6B show cross-sectional views (“A”) and plan (top) views (“B”) of various stages in the manufacture of a protective film for an EUV photomask according to embodiments of the present disclosure. It should be understood that, for additional embodiments of the method, additional operations may be provided before, during, and after the processes shown in Figures 5A to 6B, and some of these operations may be replaced or eliminated. The order of operations / processes may be interchanged. The materials, configurations, methods, processes, and / or dimensions explained with respect to the above embodiments are suitable for the following embodiments, and their detailed description may be omitted.

[0035] As shown in Figures 5A and 5B, a layer of CNTs 90 is formed on the support film 80 by one or more of the methods described above. In some embodiments, the layer of nanotubes 90 includes single-walled nanotubes, multi-walled nanotubes, or a mixture thereof. In some embodiments, the layer of carbon nanotubes 90 includes only single-walled nanotubes.

[0036] Next, as shown in Figures 6A and 6B, the protective film frame or boundary 15 is attached to the layer of the carbon nanotube 90. In some embodiments, the protective film frame 15 is formed of one or more layers of crystalline silicon, polycrystalline silicon, silicon oxide, silicon nitride, aluminum oxide, or ceramic material. In some embodiments, as shown in Figure 6B, the protective film frame 15 has a rectangular (including square) frame shape, which is larger than the black boundary region of the EUV mask and smaller than the substrate of the EUV mask. In some embodiments, the protective film frame is attached to the nanotube layer by a cold soldering operation.

[0037] In some embodiments, the nanotube 90 layer and the support film 80 are then cut into a rectangular shape having the same size as or slightly larger than the protective film frame 15, and then the support film 80 is detached or removed. When the support film 80 is made of organic material, the support film 80 is removed by wet etching using an organic solvent.

[0038] The sequential operation of a method 700 for manufacturing a protective film according to some embodiments of the present disclosure is shown in Figures 7A to 7E. The frame 15 is initially wetted with a suitable solvent (such as ethanol) to facilitate attachment of the frame 15 to the layer of nanotubes 90, as shown in Figure 7A. The frame 15 contacts the layer of nanotubes 90, and the structure is dried by air drying or vacuum drying, as shown in Figure 7B, followed by removal of the support film, as shown in Figure 7C. In Figure 7D, the layer of nanotubes 90 is treated with a suitable solvent vapor 710 (such as ethanol vapor) to densify the nanotube layer. The solvent vapor promotes the binding of nanotubes within the nanotube layer. During solvent evaporation, CNTs contact and bond with each other, thereby forming CNT bundles. Subsequently, in Figure 7E, the protective film structure is dried by air drying or vacuum drying to provide a protective film structure 720 having a nanotube network film 100. In some embodiments, the solvent evaporation operation includes immersing the CNT protective membrane in a higher boiling point solvent, such as isoamyl acetate, and washing and drying the nanotube network membrane 100.

[0039] Another method 800 for manufacturing a protective film according to some embodiments of the present disclosure is sequentially operated as shown in Figures 8A to 8D. This method is similar to the method disclosed in Figures 7A to 7E, except that this method does not include the operation of wetting the frame 15 with a solvent. Therefore, the operation shown in Figure 8A corresponds to the operation shown in Figure 7B, the operation shown in Figure 8B corresponds to the operation shown in Figure 7C, the operation shown in Figure 8C corresponds to the operation shown in Figure 7D, and the operation shown in Figure 8D corresponds to the operation shown in Figure 7E.

[0040] Figure 9A shows a schematic diagram of a CVD device 900, which includes a CVD reactor 965 for forming an inorganic or ceramic layer covering CNT nanotubes or CNT bundles to form an inorganic or ceramic coating film 915. In some embodiments, the CVD device is a low-pressure thermal CVD device. In some embodiments, the CVD reactor includes a quartz tube wall 905 and a heater 910 surrounding the quartz tube wall 905. The device 900 may further include a source of inorganic or ceramic layer material 935, which includes inorganic or ceramic source material 940. In an embodiment, when BNNTs are formed over CNTs, H3NBH3 is used as a B and N precursor to deposit a BN coating layer over the CNTs or CNT bundles. An H3NBH3 flow 950 is introduced into the reactor through a conduit 945 from the source of the inorganic or ceramic layer material 935. In this embodiment, a mixture 960 of 3-10 mol% H2 and Ar is introduced into the reactor at a flow rate of about 300 sccm as a carrier gas. In some embodiments, Ar is also used as a purge gas. In some embodiments, the temperature in the reactor during the coating operation ranges from about 800°C to about 1200°C, and in other embodiments, it ranges from about 1000°C to about 1100°C. In some embodiments, the operating pressure in the reactor ranges from about 280 Pa to about 320 Pa, and in other embodiments, it ranges from about 290 Pa to about 310 Pa. Due to the high temperatures in the process of forming the inorganic or ceramic coating, the metal-containing catalyst in the CNT or CNT bundle is reduced or even removed, thereby improving the EUV transmittance of the membrane.

[0041] In some embodiments, the boron nitride layer source material comprises a mixture of H3NBH3 and h-BN powder in a weight ratio ranging from about 1:5 to 1:15. In some embodiments, the powder mixture is maintained at a temperature ranging from about 80°C to about 100°C before being introduced into the CVD reactor.

[0042] In the example using H3NBH3 powder and Ar containing 3 mol% H2 at a flow rate of 300 sccm, the duration of BN coating deposition was about 1 hour, the operating temperature was about 1000°C to 1100°C, and the operating pressure was about 300 Pa.

[0043] In another example using H3NBH3 powder and Ar containing 3 mol% H2 at a flow rate of 300 sccm, the BN coating deposition time was about 3 hours, the operating temperature was about 1057°C, and the operating pressure was about 300 Pa.

[0044] In some embodiments, the inorganic or ceramic coated membrane 915 has a thickness ranging from about 5 nm to about 200 nm. In other embodiments, the membrane thickness ranges from about 10 nm to about 100 nm. In some embodiments, the CNT is coated with about 2 to about 30 walls.

[0045] Figure 9B is a diagram used to depict CNT 90 coated with one or more inorganic or ceramic layers 920 formed in the coating operation shown in Figure 9A. Other suitable inorganic or ceramic coatings besides boron nitride include any one or more of the following: SiC, MoS2, MoSe2, WS2, WSe2, SnS2, SnS, ZrO2, ZrO, and TiO2.

[0046] In some embodiments, the CVD reactor is a quartz tube furnace as shown in Figures 10A and 10B.

[0047] Figure 10A shows the use of a vertical furnace 1010, according to some embodiments of the present disclosure, to form an inorganic or ceramic coating layer over the CNTs or CNT bundles of a CNT network protective film 100, wherein a plurality of protective films 100 are horizontally arranged in the vertical furnace 1010. Therefore, a plurality of CNT network protective films can be simultaneously coated with inorganic or ceramic layers.

[0048] Figure 10B shows the use of a horizontal furnace 1020 to form an inorganic or ceramic coating layer over the CNTs or CNT bundles of a CNT network protective film 100, wherein a plurality of protective films 100 are vertically arranged in the horizontal furnace 1020. Therefore, a plurality of CNT network protective films can be simultaneously coated with inorganic or ceramic layers.

[0049] In some embodiments, the precursors used to form BNNT include: B2O3, H3BO3, B3H6N3, and BF3 for boron; and NH3 / Ar, NH3, and CO(NH2)2 for nitrogen. In some embodiments, a mixture of H3NBH3 and NaBH4 with NH4Cl is used as a precursor for both boron and nitrogen in boron nitride.

[0050] In some embodiments, H3BO3 is used as a boron precursor, N2 is used as a nitrogen precursor, and Ar gas is used as a carrier gas. Ar gas is also used as a purge gas to deposit the boron nitride coating 930. In some embodiments, the operating temperature ranges from about 800°C to about 1200°C, and in other embodiments, it ranges from about 900°C to about 1100°C. In some embodiments, the operating pressure ranges from about 0.8 atm to about 1.2 atm, and in other embodiments, it ranges from about 0.9 atm to about 1.1 atm.

[0051] In some embodiments, B₂O₃ is used as a B precursor, NH₃ is used as a N precursor, Ar gas is used as a carrier gas, the ratio of NH₃ to Ar is 1:4, and Ar gas is used as a purge gas to deposit the BN coating layer 930. In some embodiments, the operating temperature ranges from about 1000°C to about 1400°C, and in other embodiments, it ranges from about 1100°C to about 1300°C. In some embodiments, the operating pressure ranges from about 0.8 atm to about 1.2 atm, and in other embodiments, it ranges from about 0.9 atm to about 1.1 atm. In an example, the BN coating layer deposition duration is about 1 hour, the NH₃ / Ar flow rate ranges from about 100 sccm to about 300 sccm, the operating temperature is about 1200°C, and the operating pressure is about 1 atm.

[0052] In another example, B2O3 was first dissolved in CNTs and SDS at about 80°C for about 30 minutes. Then, BN coating deposition was performed for about 4 hours at an NH3 flow rate of about 100 sccm, an operating temperature of about 1200°C, and an operating pressure of about 1 atm.

[0053] In another example, B2O3 was first dissolved in ethanol at about 60°C. Then, BN coating deposition was performed for about 3 minutes at an NH3 flow rate of about 30 sccm, an Ar flow rate of about 300 sccm, an operating temperature of about 900°C, and an operating pressure of about 10-3 Torr (based on Ar).

[0054] In some embodiments, H3BO3 is used as a B precursor, NH3 is used as a N precursor, the flow rate is about 50 standard cubic centimeters per minute (sccm), and Ar gas is used as a purge gas to deposit the coating layer 930. In some embodiments, the operating temperature ranges from about 800°C to about 1000°C. In some embodiments, the operating pressure ranges from about 0.9 atm to about 1.1 atm. In an example, the duration of BN coating layer deposition is about 1 hour at an NH3 flow rate of about 50 sccm, an operating temperature of about 900°C, and an operating pressure of about 1 atm (Ar environment).

[0055] In another example of using H3BO3 powder as a B precursor, N2 was used as a N precursor, and the BN coating deposition time was about 1 hour at an operating temperature of about 900°C and an operating pressure of about 1 atm (N2 environment).

[0056] In another example, H3BO3 and CO(NH2)2 were first dissolved in CNT and ethanol at room temperature for about 1 hour. Then, while NH3 was flowing at a flow rate of about 200 ml / min, BN coating deposition was performed for about 3 hours at an operating temperature of about 900°C and an operating pressure of about 1 atm (N2 environment).

[0057] In another example, H3BO3 and CO(NH2)2 were first dissolved in CNT and ethanol at room temperature for about 1 hour. Then, BN coating deposition was performed for about 2 hours at an operating temperature of about 1000°C and an operating pressure of about 1 atm (N2 environment).

[0058] In some embodiments, NaBH4 in powder form is sublimated and used as a B precursor, NH4Cl is used as a N precursor, and Ar gas is used as a purge gas to form the coating layer 930. The BN coating layer deposition is performed for approximately 10 hours. In some embodiments, the operating temperature ranges from approximately 400°C to approximately 700°C, and in other embodiments, it ranges from approximately 500°C to approximately 600°C. In some embodiments, the operating pressure ranges from approximately 0.8 atm to approximately 1.2 atm, and in other embodiments, it ranges from approximately 0.9 atm to approximately 1.1 atm.

[0059] In another example, BF3 was used as a B precursor and NH3 was used as a N precursor. The BN coating deposition was performed for about 3 hours at an operating temperature of about 1100°C and a pressure of about 2.3 Torr.

[0060] In another example, B3H6N3 liquid was used as a B precursor, and Ar was used as a carrier gas at a flow rate of about 5 sccm. The BN coating deposition was performed for about 30 minutes to about 2 hours at an operating temperature of about 900°C and a pressure of about 300 Pa.

[0061] In other embodiments, other source materials are used as precursors to deposit coatings of other materials, such as SiC and transition metal dichalcogenides.

[0062] In some embodiments, SiC is formed or grown by CVD using silane (SiH4) and light hydrocarbons (C2H4 or C3H8) as precursors diluted in a hydrogen (H2) stream, with growth temperatures ranging from about 1500°C to about 1600°C and pressures ranging from about 100 mbar to about 300 mbar.

[0063] In some embodiments, MoO3 or MoCl5 is used as a Mo precursor by forming or growing MoS2 via CVD. Solid MoO3 or MoCl5 in powder form is evaporated and converted into MoS2 by reacting with sulfur vapor at a high temperature (>800°C). The MoO3 or MoCl5 is placed in a region of the furnace at a temperature >800°C to allow it to evaporate. Sulfur vapor is introduced into the furnace as an S precursor by heating the sulfur powder and carrying it with an Ar stream. These precursors react to produce MoS2.

[0064] In some embodiments, the inorganic or ceramic layer is formed at a temperature ranging from about 500°C to about 1200°C and an operating pressure ranging from about 10⁻³ Torr to about 760 Torr, with the coating deposition time ranging from about 3 minutes to about 10 hours. In some embodiments, the duration of coating deposition ranges from about 1 hour to about 4 hours.

[0065] After the coating layer 930 is formed, the CNTs are at least partially removed. In some embodiments, the CNTs are removed by an oxidation process. In some embodiments, a protective film structure 1110 having inorganic or ceramic-coated CNTs is placed in a furnace 1100, as shown in Figure 11A. In some embodiments, the furnace is a quartz tube furnace having a quartz wall 1120 surrounded by a heater 1130. The CNTs are removed by allowing air 1150 to enter the furnace through an air inlet 1140 and pass over the protective film structure 1110. In some embodiments, the furnace is heated to a temperature ranging from about 500°C to about 700°C for about 1 hour to about 3 hours, while air flows through the furnace at a flow rate ranging from about 1 L / min to about 10 L / min. In other embodiments, the air flow rate ranges from about 1.8 L / min to about 5 L / min. The air can be used to oxidize the CNTs, and in some embodiments, the oxygen used for oxidation is mixed with another carrier gas, such as argon. The inorganic or ceramic coating does not react with oxygen and therefore is not oxidized during the CNT removal operation. On the other hand, CNTs react with oxygen to form carbon dioxide, which is carried away by a carrier gas. In some embodiments, CNTs are completely removed from the protective membrane structure. Figure 11B shows a portion of a protective membrane network formed of nanotubes 930 according to some embodiments of this disclosure, where CNTs have been completely removed.

[0066] Figures 12A, 12B, and 12C show three-dimensional and cross-sectional views of nanotube structures manufactured by a manufacturing process according to embodiments of the present disclosure. Figure 12A illustrates a CNT 90 formed according to an embodiment of the present disclosure. Figure 12B illustrates an inorganic or ceramic nanotube 930 formed around the CNT 90 according to an embodiment of the present disclosure, and Figure 12C illustrates the nanotube 930 after the CNTs have been removed.

[0067] In some embodiments, the bonding bundle 1310 of CNTs is formed by Joule heating, as shown in Figures 13A and 13B. As shown in Figure 13A, a protective film 10, including a membrane 100 and a frame 15 (as shown in Figures 1A and 1B), is placed above an insulating support 50 and held at an edge portion of the protective film by portions of the insulating support 50 and electrodes 1320 disposed above the protective film 10. In some embodiments, the insulating support 50 is made of ceramic, and the electrodes 1320 are made of metal, such as tungsten, copper, or steel. The electrodes 1320 are attached to contact the membrane 100. In some embodiments, the electrodes 1320 are attached to two side portions of the membrane 100 (e.g., the left and right sides). In some embodiments, the electrodes 1320 are connected to a current source (power supply) 1330 by wires.

[0068] As shown in Figure 13A, a Joule heating device 1300, on which a membrane 100 formed of one or more nanotube materials is mounted, is placed in a vacuum chamber 1340. In some embodiments, the vacuum chamber 1340 includes a bottom portion and an upper (cover) portion in which the Joule heating device is placed, and a gasket (e.g., an O-ring) is disposed between the bottom portion and the upper portion. The wiring of the Joule heating device is connected to an external wiring, which is connected to a power supply 1330.

[0069] In the Joule heating operation, in some embodiments, the vacuum chamber is evacuated to a pressure equal to or below 10 Pa. In some embodiments, the pressure is greater than 0.1 Pa. An electrical supply 1330 applies current to the membrane 100, causing the current to pass through the membrane and generate heat. In some embodiments, the current is DC; in other embodiments, the current is AC or a pulsed current.

[0070] In some embodiments, the current from the power supply 1330 is adjusted such that the membrane is heated at a temperature ranging from about 800°C to 2000°C. In some embodiments, the lower limit of the temperature is about 1000°C, 1200°C, or 1500°C, and the upper limit of the temperature is about 1500°C, 1600°C, or 1800°C, to allow the separated nanotubes to join together and form a bundle.

[0071] In some embodiments, the protective membrane frame 15 is made of a ceramic or metal or metallic material having a resistance higher than that of the carbon nanotube membrane 100.

[0072] In some embodiments, the Joule heating treatment is performed in an inert ambient gas, such as N2 and / or Ar. In some embodiments, the Joule heating treatment is performed for about five seconds to about 60 minutes, and in other embodiments, it is performed for about 30 seconds to about 15 minutes.

[0073] As shown in Figure 13B, in some embodiments, a Joule heating operation connects individual, separate nanotubes 90 (single-walled or multi-walled nanotubes) to form a nanotube bundle 1310 with a seamless graphite structure, wherein the nanotubes are firmly joined or connected, rather than merely in contact with each other. Two or more nanotubes 90 may be joined (joined or connected) to form the nanotube bundle 1310. In some embodiments, 2 to 15 nanotubes are joined to form a medium bundle. In some embodiments, 16 to 100 nanotubes are joined to form a large bundle. In some embodiments, more than 100 nanotubes are joined to form a very large bundle.

[0074] Figures 14, 15, 16, and 17 show the structures of various films 100 for protective films of EUV photomasks according to embodiments of the present disclosure. As shown in Figure 1A or 1B, the protective film includes a frame 15 and a film 100 attached to the frame 15. Figures 14 through 17 show detailed cross-sectional views of a portion of the protective film 100 and one of the multi-walled nanotubes of the protective film.

[0075] As shown in Figure 14, in some embodiments, the membrane 100 includes a plurality of nanotube bundles 1310, each nanotube bundle 1310 including a plurality of single-walled or multi-walled CNTs 90 bonded together. The plurality of bonded CNTs 90 are coaxially arranged. The membrane 100 further includes a covering layer 930 made of a plurality of coaxial walls 930 made of a material different from the CNTs, surrounding each of the plurality of nanotube bundles 1310.

[0076] In some embodiments, as shown in Figure 14, the inner diameter D1 of the plurality of multiwall carbon nanotubes (MWCNTs) 90 is equal to or less than 2 nm (D1 ≤ 2 nm). In some embodiments, each nanotube 90 has an outer diameter D2 of about 2 nm to about 20 nm, depending on the number of walls. In some embodiments, each CNT 90 includes 1 to about 20 walls. In some embodiments, each CNT 90 includes about 3 to about 15 walls. In some embodiments, each CNT 90 includes about 4 to about 10 walls. In some embodiments, the outer diameter of each CNT 90 ranges from about 2 nm to about 20 nm. In some embodiments, the outer diameter of each CNT 90 ranges from about 4 nm to about 10 nm. In some embodiments, the plurality of nanotubes 90 do not include any layers made of different materials. In other words, each of the plurality of nanotubes 90 is made of the same material.

[0077] In some embodiments, depending on the size of the CNT bundle 1310, the inner diameter D3 of the cladding layer 930 ranges from about 10 nm to about 100 nm. In some embodiments, the inner diameter D3 of the cladding layer 930 ranges from about 20 nm to about 50 nm. In some embodiments, the cladding layer 930 surrounds about 3 to about 100 CNTs 90. In some embodiments, the cladding layer 930 surrounds about 10 to about 50 CNTs 90. In some embodiments, the cladding layer 930 surrounds about 15 to about 40 CNTs. In some embodiments, the cladding layer 930 surrounds more than 100 CNTs 90. In some embodiments, the cladding layer 930 includes 1 to about 20 walls. In some embodiments, the cladding layer 930 includes about 3 to about 15 walls. In some embodiments, the cladding layer 930 includes about 4 to about 10 walls. In the example, the coating layer 930 includes four walls; has an inner diameter D3 of about 20 nm; and surrounds 19 MWCNT 90, each of which has four walls, an inner diameter less than or equal to 2 nm, and an outer diameter of about 4.2 nm.

[0078] As shown in Figure 15, in some embodiments, membrane 100 includes a plurality of nanotubes made of a coating layer 930. In some embodiments, as described herein, the CNTs 90 in the membrane structure of Figure 14 are removed by an oxidation operation. Although Figure 15 illustrates an embodiment in which the CNTs are completely removed, in some embodiments, the CNTs are only partially removed by an oxidation operation.

[0079] In other embodiments, as shown in Figure 16, when the inner diameter D1 of the CNT 90 is greater than 2 nm (D1 > 2 nm), the plurality of CNT 90s further include one or more walls 1610 of inorganic or ceramic material filled within the innermost wall of the CNT 90. In some embodiments, the number of walls 1610 filling the inner diameter of the CNT 90 ranges from 1 to about 4 walls. In some embodiments, the filling of the innermost diameter D1 of the CNT 90 with inorganic or ceramic material depends on the operating temperature of the coating operation. In some embodiments, at higher operating temperatures, a larger amount of inorganic or ceramic material is filled within the innermost wall of the CNT 90.

[0080] As shown in Figures 14 and 16, in some embodiments, the first material used to form the nanotube 90 includes a carbon-based nanotube material, and the different second materials used to form the coaxial cladding layer 930 and the coaxial inner wall 1610 filling the innermost wall of the CNT include one or more selected from BN, h-BN, SiC, MoS2, MoSe2, WS2, WSe2, SnS2, SnS, ZrO2, ZrO, or TiO2. In some embodiments, two adjacent walls or coaxial inner walls 1610 in the cladding layer 930 are made of different materials.

[0081] In some embodiments, the CNTs 90 of the membrane structure of Figure 16 are removed by the oxidation process disclosed herein to provide the membrane structure 100 of Figure 17. As shown in Figure 17, in some embodiments, the membrane structure 100 includes a plurality of inorganic or ceramic nanotubes 1610 surrounded by an inorganic or ceramic coating layer 930. Although the CNTs are completely removed in the structure shown in Figure 17, in some embodiments, the CNTs are only partially removed by the oxidation process.

[0082] Figures 18A, 18B, 18C, and 18D are illustrations of transmission electron microscopy (TEM) images of the BNNT film structure according to embodiments of the present disclosure. Figures 18E to 18L are detailed illustrations of TEM images of the BNNT-coated CNT film structure according to embodiments of the present disclosure. Figures 18F, 18H, 18J, and 18L are detailed illustrations of various regions of the BNNT-coated CNT film structure. Figure 18E is a detailed cross-sectional view of region A in Figure 18F. Figure 18G is a detailed cross-sectional view of region B in Figure 18H. Figure 18I is a detailed cross-sectional view of region C in Figure 18J. Figure 18K is a detailed cross-sectional view of region D in Figure 18L. As shown in Figures 18E, 18G, 18I, and 18K, a multiwall (MW) BNNT surrounds the MWCNT. In some embodiments, the number of walls of the MWBNNT varies along the length of the MWCNT.

[0083] Detailed description of TEM images of the same region of the BNNT-coated CNT film structure in Figures 18M, 18N, and 18O. Figure 18M shows the carbon distribution in the TEM image, Figure 18N shows the boron distribution, and Figure 18O shows the nitrogen distribution.

[0084] Figures 19 to 21 are flowcharts showing a method for manufacturing a protective film according to an embodiment of the present disclosure. It should be understood that, for other embodiments of the method, additional operations may be provided before, during, and after the processes shown in Figures 19 to 21, and some of the operations described below may be replaced or eliminated. The order of operations / processes may be interchanged.

[0085] The method 1900 for manufacturing a protective film according to an embodiment of the present disclosure is shown in the flowchart of Figure 19. In operation S1910, carbon nanotubes (CNTs) 90 are grown. In some embodiments, in operation S1920, CNTs 90 are grown over a filter 80. In operation S1930, CNTs 90 are covered with one or more nanotubes 930 made of different materials. In some embodiments, in operation S1940, a frame 15 is brought into contact with the CNTs. In operation S1950, the CNTs are removed. In some embodiments, in operation S1960, the filter is removed. In some embodiments, the different materials include one or more of boron nitride, hexagonal boron nitride (h-BN), SiC, MoS2, MoSe2, WS2, WSe2, SnS2, SnS, ZrO2, ZrO, and TiO2. In some embodiments, in operation S1950, CNTs are removed by oxidation. In some embodiments, during operation S1950, oxidizing CNTs includes heating the CNTs at a temperature ranging from 500°C to 700°C.

[0086] Another method 2000 for manufacturing a protective membrane according to an embodiment of the present disclosure is shown in the flowchart of Figure 20. In operation S2010, a membrane 100 comprising a plurality of carbon nanotubes 90 is formed over a filter 80. In operation S2020, the membrane 100 is attached to a frame 15. In operation S2030, an inorganic nanotube 930 is formed around each of the carbon nanotubes 90. The inorganic nanotubes 930 are made of a different material than the carbon nanotubes 90. In some embodiments, in operation S2040, after the membrane is attached to the frame 15, the filter 80 is removed. In operation S2050, the carbon nanotubes are at least partially removed. In some embodiments, in operation S2050, the carbon nanotubes 90 are at least partially removed by oxidizing the carbon nanotubes 90. In some embodiments, in operation S2050, the carbon oxide nanotube 90 includes heating the carbon nanotube 90 at a temperature ranging from 500°C to 700°C. In some embodiments, in operation S2050, the carbon nanotube is completely removed. In some embodiments, different materials include one or more of boron nitride, hexagonal boron nitride (h-BN), SiC, MoS2, MoSe2, WS2, WSe2, SnS2, SnS, ZrO2, ZrO, and TiO2. In some embodiments, in operation S2030, forming the inorganic nanotube 930 includes forming a multi-walled inorganic nanotube surrounding each of the carbon nanotubes 90. In some embodiments, a plurality of carbon nanotubes include multi-walled carbon nanotubes 90.

[0087] Another method 2100 for manufacturing a protective film according to an embodiment of the present disclosure is shown in the flowchart of Figure 21. In operation S2110, a plurality of carbon nanotubes 90 are formed. Each of the carbon nanotubes 90 includes one or more walls. In operation S2120, the plurality of carbon nanotubes 90 are joined together to form a nanotube bundle 1310. In operation S2130, a first inorganic nanotube 930 is formed around the nanotube bundle 1310. The first inorganic nanotube 930 is made of a material different from the carbon nanotubes 90. In some embodiments, in operation S2140, before forming the first inorganic nanotube, a second inorganic nanotube 1610 is formed on the innermost wall of the plurality of nanotubes 90. The second inorganic nanotube 1610 is made of a material different from the carbon nanotubes 90. In operation S2150, the nanotube bundle is at least partially removed. In some embodiments, the second inorganic nanotube 1610 includes a plurality of coaxial walls. In some embodiments, the first inorganic nanotube 930 includes a plurality of coaxial walls. In some embodiments, in operation S2150, the nanotube bundle is completely removed.

[0088] The properties of BNNT and CNT are compared in Table 1. Table 1 Boron nitride nanotubes (BNNT) carbon nanotubes (CNT) Appearance white black electrical conductivity Insulation, wide bandgap (5~6 eV) Metallized or semiconductive (0.5~2 eV) Young's modulus 1.2 Tpa 1.09~1.25 Tpa thermal conductivity 350±20 Wm -1 K -1 300±20 Wm -1 K -1 thermal stability Stable at 800~900 ºC Stable at 500~700 ºC Optical properties Transparent to visible light and IR, absorbs UV in some regions. Full-spectrum absorption

[0089] As shown in Table 1, BNNT has higher thermal conductivity and higher thermal stability than CNT.

[0090] Figure 22A shows a flowchart of a method 2200 for manufacturing a semiconductor device, and Figures 22B, 22C, 22D, and 22E show sequential manufacturing methods for producing a semiconductor device according to embodiments of the present disclosure. A semiconductor substrate or other suitable substrate is provided to be patterned to form integrated circuits thereon. In some embodiments, the semiconductor substrate comprises silicon. Alternatively or otherwise, the semiconductor substrate comprises germanium, silicon germanium, or other suitable semiconductor materials, such as group III-V semiconductor materials. At S2210 in Figure 22A, a target layer 115 to be patterned is formed over the semiconductor substrate 110. In some embodiments, the target layer 115 is a semiconductor substrate. In some embodiments, the target layer 115 includes a conductive layer, such as a metal layer or a polycrystalline silicon layer; a dielectric layer, such as silicon oxide, silicon nitride, SiON, SiOC, SiOCN, SiCN, hafnium oxide, or aluminum oxide; or a semiconductor layer, such as an epitaxially formed semiconductor layer. In some embodiments, the target layer 115 is formed over an underlying structure, such as an isolation structure, transistor, or wiring. At S2220, as shown in Figure 22B, a photoresist layer 120 is formed over the target layer. During subsequent optical lithography exposure operations, the photoresist layer 120 is sensitive to radiation 70 from the exposure radiation source. In this embodiment, the photoresist layer 120 is sensitive to EUV light used in the optical lithography exposure operation. The photoresist layer 120 may be formed over the target layer 115 by spin-coating or other suitable techniques. The coated photoresist layer may be further baked to remove solvent from the photoresist layer. At S2230, as shown in Figure 22C, the photoresist layer 120 is patterned in the optical lithography exposure device 165 using the protective film / mask structure 160 as described above. During the optical lithography exposure operation, an integrated circuit (IC) design pattern defined on the photomask 60 is imaged onto the photoresist layer 120 to form a potential pattern thereon. Patterning of the photoresist layer further includes exposing the photoresist layer during development to form a patterned photoresist layer with one or more openings 125. In one embodiment, the photoresist layer is a positive-tone photoresist layer, and the exposed portions of the photoresist layer are removed during the development operation. Patterning of the photoresist layer may further include other operations, such as various baking operations at different stages. For example, a post-exposure-baking (PEB) process may be performed after the optical lithography exposure operation and before the development operation.

[0091] At S2240, the target layer 115 is patterned using the patterned photoresist layer 120 as an etching mask, as shown in Figure 22D. In some embodiments, patterning the target layer includes etching the target layer using the patterned photoresist layer as an etching mask. Portions of the target layer exposed within openings in the patterned photoresist layer are etched, while the remaining portions are protected from etching. Further, as shown in Figure 22E, the patterned photoresist layer can be removed by wet stripping or plasma ashing.

[0092] Other embodiments include other operations before, during, or after the above operations. In some embodiments, the disclosed method includes forming a fin field-effect transistor (FinFET) structure. In some embodiments, a plurality of active fins are formed on a semiconductor substrate. Such embodiments further include etching the substrate through an opening of a patterned hard mask to form trenches in the substrate; filling the trenches with a dielectric material; performing a chemical mechanical polishing (CMP) process to form shallow trench isolation (STI) features; and epitaxially growing or recessing the STI features to form fin-like active regions. In some embodiments, one or more gate electrodes are formed on the substrate. Some embodiments include forming gate spacers, doped source / drain regions, contacts for gate / source / drain features, etc. In other embodiments, the target pattern is formed as a metal connection in a multilayer interconnect structure. For example, the metal connection may be formed in an inter-layer dielectric (ILD) layer of the substrate, which has been etched to form a plurality of trenches. The trenches may be filled with a conductive material, such as metal; and the conductive material may be ground using a process such as chemical mechanical planarization (CMP) to expose the patterned ILD layer, thereby forming metal wiring within the ILD layer. The above are non-limiting examples of devices / structures that can be manufactured and / or improved using the methods described herein.

[0093] In some embodiments, according to embodiments of the present disclosure, active components are formed such as diodes, field-effect transistors (FETs), metal-oxide-semiconductor field-effect transistors (MOSFETs), complementary metal-oxide-semiconductor (CMOS) transistors, bipolar transistors, high-voltage transistors, high-frequency transistors, chip FETs, FinFETs, gate all-around FETs (GAA FETs), other three-dimensional (3D) FETs, other memory cells, and combinations thereof.

[0094] Removing CNTs reduces the absorption of EUV radiation by the protective film. The remaining coating nanotube structure provides superior mechanical properties compared to CNTs. Embodiments disclosed herein provide nanotube network films with excellent EUV radiation transmittance at wavelengths of 13.5 nm and 6.7 nm. Embodiments disclosed herein provide nanotube network films with EUV radiation transmittance up to 99% at these wavelengths, exceeding the up to 96.5% EUV transmittance of CNT-based films. The high-temperature operation for forming the inorganic or ceramic coating also removes residual metal catalysts used to form CNTs, thereby further improving EUV radiation transmittance. Embodiments disclosed herein provide high-transmittance and high-strength EUV protective films, thereby improving the manufacturing efficiency of semiconductor devices.

[0095] Embodiments of this disclosure include a method for forming a protective film, comprising growing carbon nanotubes (CNTs), coating the CNTs with one or more nanotubes made of different materials, and removing the CNTs. In embodiments, the method includes growing CNTs over a filter. In embodiments, the method includes removing the filter. In embodiments, the method includes contacting the CNTs with a frame. In embodiments, the different materials include one or more of boron nitride, hexagonal boron nitride (h-BN), SiC, MoS2, MoSe2, WS2, WSe2, SnS2, SnS, ZrO2, ZrO, and TiO2. In embodiments, the CNTs are removed by oxidation. In embodiments, oxidation of the CNTs includes heating the CNTs at a temperature ranging from 500°C to 700°C. In embodiments, the CNTs comprise multi-walled carbon nanotubes.

[0096] Another embodiment of this disclosure includes a method of manufacturing a protective membrane, comprising forming a membrane comprising a plurality of carbon nanotubes over a filter. The membrane is attached to a frame. Inorganic nanotubes are formed around each of the carbon nanotubes. The inorganic nanotubes are made of a different material than the carbon nanotubes. The carbon nanotubes are at least partially removed. In an embodiment, the method includes removing the filter after attaching the membrane to the frame. In an embodiment, the different materials include one or more of boron nitride, hexagonal boron nitride (h-BN), SiC, MoS2, MoSe2, WS2, WSe2, SnS2, SnS, ZrO2, ZrO, and TiO2. In an embodiment, the carbon nanotubes are at least partially removed by oxidizing the carbon nanotubes. In an embodiment, oxidizing the carbon nanotubes includes heating the carbon nanotubes at a temperature ranging from 500°C to 700°C. In an embodiment, the carbon nanotubes are completely removed. In an embodiment, forming an inorganic nanotube includes forming a multi-walled inorganic nanotube surrounding each of the carbon nanotubes.

[0097] Another embodiment of this disclosure includes a method of manufacturing a protective membrane, comprising forming a plurality of carbon nanotubes. Each of the carbon nanotubes includes one or more walls. The plurality of carbon nanotubes are joined together to form a nanotube bundle. A first inorganic nanotube is formed around the nanotube bundle. The first inorganic nanotube is made of a material different from the carbon nanotubes. The nanotube bundle is at least partially removed. In an embodiment, the method includes forming a second inorganic nanotube on the innermost wall of the plurality of nanotubes, wherein the second inorganic nanotube is made of a material different from the carbon nanotubes. In an embodiment, the second inorganic nanotube includes a plurality of coaxial walls. In an embodiment, the first inorganic nanotube includes a plurality of coaxial walls. In an embodiment, the nanotube bundle is completely removed. Another embodiment of this disclosure includes a protective membrane comprising a membrane comprising a plurality of inorganic nanotubes. The membrane does not include carbon nanotubes. A frame is disposed above the membrane. In embodiments, the inorganic nanotubes include one or more of boron nitride, hexagonal boron nitride (h-BN), SiC, MoS2, MoSe2, WS2, WSe2, SnS2, SnS, ZrO2, ZrO, and TiO2. In embodiments, each inorganic nanotube includes a plurality of coaxial walls. In embodiments, each inorganic nanotube includes 3 to 30 coaxial walls. In embodiments, at least one of the plurality of coaxial walls is formed of a material different from another of the plurality of coaxial walls. In embodiments, the membrane has a thickness ranging from 10 to 100 nm. In embodiments, the inorganic nanotubes have an inner diameter ranging from 0.5 nm to 10 nm. Another embodiment of this disclosure includes a protective membrane comprising a membrane comprising a plurality of inorganic nanotube bundles. Each of the plurality of inorganic nanotube bundles includes a plurality of first inorganic nanotubes surrounded by second inorganic nanotubes. The first and second inorganic nanotubes independently comprise one or more of boron nitride, hexagonal boron nitride (h-BN), SiC, MoS2, MoSe2, WS2, WSe2, SnS2, SnS, ZrO2, ZrO, and TiO2. A frame is disposed above the membrane. In an embodiment, each of the first inorganic nanotubes comprises a plurality of coaxial walls. In an embodiment, each of the first inorganic nanotubes comprises 3 to 30 coaxial walls. In an embodiment, at least one of the plurality of coaxial walls is formed of a different material than another of the plurality of coaxial walls.

[0098] In an embodiment, the second inorganic nanotube includes a plurality of coaxial walls. In an embodiment, the second inorganic nanotube surrounds 3 to 100 first inorganic nanotubes. In an embodiment, the film has a thickness ranging from 10 to 100 nm. In an embodiment, the first inorganic nanotubes have an inner diameter ranging from 0.5 nm to 10 nm. In an embodiment, the first inorganic nanotubes are arranged parallel to each other in a cross-sectional view.

[0099] Another embodiment of this disclosure includes a protective membrane comprising a membrane disposed above a frame. The membrane includes a plurality of first multi-walled nanotubes. Each of the first multi-walled nanotubes surrounds a plurality of second multi-walled nanotubes. Each of the plurality of second multi-walled nanotubes surrounds a third multi-walled nanotube. The second and third multi-walled nanotubes are made of different materials. In an embodiment, the second multi-walled nanotubes are carbon nanotubes. In an embodiment, the first multi-walled nanotubes include one or more of boron nitride, hexagonal boron nitride (h-BN), SiC, MoS2, MoSe2, WS2, WSe2, SnS2, SnS, ZrO2, ZrO, and TiO2. In an embodiment, each of the first multi-walled nanotubes surrounds 3 to 100 second multi-walled nanotubes.

[0100] It should be understood that not all advantages need to be disclosed herein, no particular advantage needs to be used in all embodiments or instances, and other embodiments or instances may provide different advantages.

[0101] The foregoing summarizes the features of several embodiments, enabling those skilled in the art to better understand the nature of this disclosure. Those skilled in the art should understand that this disclosure can be used as a basis for designing or modifying other processes and structures for implementing the embodiments introduced herein and / or achieving the same purposes and / or advantages. Those skilled in the art should also recognize that such equivalent constructions do not depart from the spirit and scope of this disclosure, and that such equivalent constructions can be modified, replaced, and substituted in various ways without departing from the spirit and scope of this disclosure. [Simplified Explanation of the Diagram]

[0004] The features of this disclosure are best understood by reading in conjunction with the accompanying drawings from the following detailed description. It should be noted that, in accordance with industry standards, the various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or decreased for clarity of explanation. Figures 1A and 1B show nanotubes and protective films for EUV photomasks according to embodiments of this disclosure. Figures 2A, 2B, 2C, and 2D show various views of multi-walled nanotubes according to embodiments of this disclosure. Figures 3A, 3B, and 3C show the process stages of manufacturing the protective film for EUV photomasks according to embodiments of this disclosure. Figure 4 shows the process stages of manufacturing the protective film for EUV photomasks according to embodiments of this disclosure. Figures 5A and 5B show cross-sectional and plan views (top views) of one of the various stages of manufacturing the protective film for EUV photomasks according to embodiments of this disclosure. Figures 6A and 6B show cross-sectional and plan views (top views) of one of the various stages of manufacturing a protective film for an EUV photomask according to an embodiment of the present disclosure. Figures 7A, 7B, 7C, 7D, and 7E show the process flow of the various stages of manufacturing a protective film for an EUV photomask according to an embodiment of the present disclosure. Figures 8A, 8B, 8C, and 8D show the process flow of the various stages of manufacturing a protective film for an EUV photomask according to an embodiment of the present disclosure. Figure 9A shows the process stages of manufacturing a protective film for an EUV photomask according to an embodiment of the present disclosure. Figure 9B shows the nanotube structure produced by the process stages. Figures 10A and 10B show the formation of a coating layer over a nanotube bundle according to an embodiment of the present disclosure. Figure 11A shows the process stages of manufacturing a protective film for an EUV photomask according to an embodiment of the present disclosure. Figure 11B shows the nanotube structure produced by the process stages. Figures 12A, 12B, and 12C show nanotube structures manufactured using a process according to an embodiment of the present disclosure. Figures 13A and 13B show nanotube bundles formed into a bond according to an embodiment of the present disclosure. Figure 14 shows the structure of a protective film for an EUV photomask according to an embodiment of the present disclosure. Figure 15 shows the structure of a protective film for an EUV photomask according to an embodiment of the present disclosure. Figure 16 shows the structure of a protective film for an EUV photomask according to an embodiment of the present disclosure. Figure 17 shows the structure of a protective film for an EUV photomask according to an embodiment of the present disclosure. Figures 18A, 18B, 18C, 18D, 18E, 18F, 18G, 18H, 18I, 18J, 18K, 18L, 18M, 18N, and 18O are TEM images illustrating the membrane structures according to embodiments of the present disclosure. Figure 19 shows a flowchart of a method for manufacturing a protective film for an EUV photomask according to an embodiment of the present disclosure.Figure 20 shows a flowchart of a method for manufacturing a protective film for an EUV photomask according to an embodiment of the present disclosure. Figure 21 shows a flowchart of a method for manufacturing a protective film for an EUV photomask according to an embodiment of the present disclosure. Figure 22A shows a flowchart of a method for manufacturing a semiconductor device according to an embodiment of the present disclosure, and Figures 22B, 22C, 22D, and 22E show the sequential manufacturing operations of the method for manufacturing a semiconductor device. [Biomaterial Storage]

[0103] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A method for manufacturing a protective film structure for extreme ultraviolet lithography, the method comprising the steps of: forming a membrane comprising a plurality of carbon nanotubes over a filter; attaching the membrane to a frame; forming an inorganic nanotube surrounding each of the carbon nanotubes, wherein the inorganic nanotubes are made of a material different from the carbon nanotubes; and removing the carbon nanotubes and leaving the inorganic nanotubes.

2. The method as described in claim 1 further includes the step of removing the filter after attaching the membrane to the frame.

3. The method as described in claim 1, wherein the different material includes one or more of boron nitride, hexagonal boron nitride (h-BN), SiC, MoS2, MoSe2, WS2, WSe2, SnS2, SnS, ZrO2, ZrO, and TiO2.

4. The method as described in claim 1, wherein the carbon nanotubes are at least partially removed by oxidation.

5. A protective film structure for extreme ultraviolet lithography, comprising: a film including a plurality of inorganic nanotube bundles, wherein each of the inorganic nanotube bundles includes a plurality of first inorganic nanotubes surrounded by a second inorganic nanotube, wherein the first and second inorganic nanotubes independently include one or more of boron nitride, hexagonal boron nitride (h-BN), SiC, MoS2, MoSe2, WS2, WSe2, SnS2, SnS, ZrO2, ZrO, and TiO2; a frame disposed above the film; and a coating layer covering the film, wherein at least two of the coating layer and the inorganic nanotube bundles are coaxial.

6. The protective film as claimed in claim 5, wherein each of the first inorganic nanotubes comprises a plurality of coaxial walls.

7. The protective film as claimed in claim 6, wherein each of the first inorganic nanotubes comprises 3 to 30 coaxial walls.

8. A protective film structure for extreme ultraviolet lithography, comprising: a film disposed above a frame, wherein the film includes a plurality of first multi-walled nanotubes, wherein each of the first multi-walled nanotubes surrounds a plurality of second multi-walled nanotubes, each of the second multi-walled nanotubes surrounds a third multi-walled nanotube, and the second multi-walled nanotubes and the third multi-walled nanotubes are made of a plurality of different materials; and a covering layer covering the film, wherein the covering layer and the film are not coaxial.

9. The protective film as described in claim 8, wherein the second multi-walled nanotubes are carbon nanotubes.

10. The protective film as claimed in claim 8, wherein the first multi-walled nanotubes include one or more of boron nitride, hexagonal boron nitride (h-BN), SiC, MoS2, MoSe2, WS2, SnS2, SnS, ZrO2, ZrO2, and TiO2.

Images