A preparation method of a large-area, self-supporting single-wall carbon nanotube extreme ultraviolet lithography mask plate protective film

Abstract

This invention relates to the field of extreme ultraviolet (EUV) lithography mask protective film preparation, specifically a method for preparing a large-area, self-supporting single-walled carbon nanotube (SUV) EUV lithography mask protective film. Single-walled carbon nanotubes are grown using a floating catalyst chemical vapor deposition (CVD) method. Ultra-long SUVs are prepared by extending the growth time of the SUVs. Utilizing the flexibility and strong van der Waals forces of the ultra-long SUVs, they self-assemble directly into interlocking and entangled SUV films during the growth process. These films are then transferred onto a hollow frame to serve as a self-supporting EUV lithography mask protective film. Under optimized conditions, SUV films with an aspect ratio > 50000 exhibit excellent mechanical properties and flexibility, achieving self-support on a 7 cm × 16 cm frame. They also possess adjustable EUV light transmittance. The prepared films hold promise as a next-generation protective film for high-power EUV lithography masks.

Description

Technical Field

[0001] This invention relates to the field of preparation of protective films for extreme ultraviolet (EUV) lithography masks, specifically a method for preparing a large-area, self-supporting single-walled carbon nanotube EUV lithography mask protective film. Background Technology

[0002] Extreme ultraviolet (EUV) lithography, as the most cutting-edge patterning transfer technology in the semiconductor manufacturing field, has become a key enabling technology supporting the mass production of chips with advanced processes of 5 nanometers and below. In the complex structure of an EUV lithography system, the protective film (Pellicle) is a crucial factor determining device yield. The photomask is essentially the projection "film" of the chip circuitry; any defects on it will be directly replicated onto the wafer, leading to chip malfunction. The EUV protective film, as an ultra-thin film covering the surface of the photomask, has the core function of protecting the expensive photomask from dust, impurities, and other contaminants during the lithography process. To ensure EUV utilization, the protective film needs extremely high EUV transmittance, typically requiring a thickness of only tens of nanometers. At this thickness, the protective film must also be self-supporting over a large area, suspending itself over the entire photomask, which places extremely stringent requirements on the selection of protective film materials. A full-size protective film typically needs an area of ​​11 cm × 14 cm, while current research both domestically and internationally usually focuses on small-sized samples. Currently, the fabrication of large-area, self-supporting photomask protective films is a technological gap both domestically and internationally, and is an essential component for next-generation high-power extreme ultraviolet lithography. Therefore, the development of large-area, self-supporting photomask protective films will greatly enhance the competitiveness of my country's next-generation information technology, flexible electronics, high-end equipment, and defense technology.

[0003] Patent CN114286965A discloses a protective film diaphragm for photolithography equipment. While mentioning that carbon nanotubes can be single-walled or multi-walled, it fails to control or limit the aspect ratio of the carbon nanotubes. This results in insufficient inter-tube bonding force, making it difficult to form a large-area self-supporting structure. Its mechanical strength is also insufficient to support the structural stability of a large-area suspended state, failing to meet the size and performance requirements of industrial-grade extreme ultraviolet (EUV) lithography masks. Patent CN108132581A discloses a photolithography mask using a carbon nanotube composite structure. Although it mentions that the carbon nanotube layer is a self-supporting structure, its application in ultraviolet lithography does not consider the high transmittance requirements of EUV light. The self-supporting structure does not reach the area required for industrial-grade mask protection, only achieving small-sized self-support and failing to adapt to various sizes of EUV lithography masks. The patent with publication number CN115398334A proposes a protective film for exposure, a protective film assembly, an exposure original, an exposure device, and a method for manufacturing the protective film for exposure. Although it mentions that the EUV transmittance of the carbon nanotube film is ≥80%, the inter-carbon nanotube overlap strength is insufficient, making it difficult to achieve large-area self-support and failing to meet the protection requirements of the photomask.

[0004] Carbon nanotube (CNT) films, due to their intrinsic high EUV transmittance, high thermal stability, and high chemical stability, are superior to other materials (pSi, SiN). x CNT protective films (such as Zr) are more suitable for high-power EUV exposure environments and are considered ideal next-generation high-power EUV lithography mask protective films. The Belgian Microelectronics Centre (IMEC), a leading research institution in the European microelectronics field, has been conducting systematic research and development of CNT protective films since 2015; Japanese chemical giant Mitsui Chemicals is also jointly involved in promoting the commercialization of CNT protective film technology, aiming to introduce CNT protective films into high-power EUV systems by 2025-2026. However, the fabrication of large-area, self-supporting CNT thin films still faces significant challenges.

[0005] Carbon nanotubes (CNTs) possess a one-dimensional tubular structure, nanometer-scale diameter, and micrometer-scale length, thus requiring them to overlap to form thin films. Currently, most commercially available carbon nanotubes are few-walled CNTs with diameters ranging from tens of nanometers. Their small aspect ratio necessitates more overlap for film formation, resulting in lower film strength and making it difficult to achieve large-area self-support at extremely thin thicknesses. Furthermore, their multi-layered tubular structure limits the transmittance of extreme ultraviolet light.

[0006] Therefore, the key to obtaining a large-area, self-supporting CNT-based extreme ultraviolet (EUV) lithography mask protective film is to increase the aspect ratio of CNTs and reduce the number of wall layers, so that they can still overlap and entangle with each other to form a strong van der Waals interaction film under high UV light transmittance, thereby achieving substrate-free, large-area self-support. Based on the above problems and challenges, this invention proposes a technology for preparing a large-area, self-supporting single-walled carbon nanotube (SWCNT) EUV lithography mask protective film. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film, which solves the key bottleneck problem that it is difficult to achieve large-area, self-supporting CNT-based protective films at home and abroad, so as to obtain an SWCNT extreme ultraviolet lithography mask protective film that meets the needs of practical applications.

[0008] The technical solution of this invention is: A method for preparing a large-area, self-supporting single-walled carbon nanotube (SUV) photomask protective film is disclosed. The method utilizes floating catalyst chemical vapor deposition to grow SUVs. By extending the growth time of the SUVs, the length and aspect ratio of the SUVs are increased. Taking advantage of the flexibility and strong van der Waals forces of the ultra-long SUVs, they directly self-assemble into interlocking, high-strength, and tough SUV films during the growth process. These high-strength and tough SUV films are then transferred to target substrates or hollow frames of different sizes and shapes to serve as a self-supporting UV photomask protective film.

[0009] The method for preparing the large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film uses Se growth promoter to improve catalyst lifetime and extends the growth time of single-walled carbon nanotubes by extending the length of the isothermal zone of the floating catalyst chemical vapor deposition furnace.

[0010] The method for preparing the large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film, in the floating catalyst chemical vapor deposition method, uses ferrocene as the catalyst precursor and ethylene as the carbon source, with a weight percentage of catalyst precursor to Se promoter precursor of 8:1~12:1.

[0011] The method for preparing the large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film refers to carbon nanotubes that are observed to consist of only a single layer of tube wall in transmission electron microscope images. Their diameter is 1.6~2.1nm, with more than 90% being 1.8~2.0nm, length >100μm, aspect ratio is 45000~70000, with more than 90% being >50000.

[0012] The method for preparing a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film produces single-walled carbon nanotubes with extremely high crystallinity and Raman spectra of I0. G / I D >200.

[0013] The method for preparing a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film involves preparing a single-walled carbon nanotube film formed by intertwining and overlapping single-walled carbon nanotubes with a large aspect ratio and high crystallinity. This film has extremely strong inter-tube interaction forces and does not require substrate support. It can be transferred to target substrates or hollow frames of various sizes and shapes to achieve large-area self-support, with a suspended area of ​​7~11 cm × 14~16 cm.

[0014] The method for preparing the large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film utilizes the difference in van der Waals forces to transfer the single-walled carbon nanotube film on the collector to a suspended target substrate or hollow frame. The target substrate or hollow frame is made of metal, quartz, glass, polycrystalline silicon, alumina, graphite, indium tin oxide (ITO), polyethylene terephthalate (PET), or polydimethylsiloxane (PDMS).

[0015] The method for preparing the large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film includes a target substrate or hollow frame material in which the metal includes Cu, Ti, Fe, Pt, Au, Ni or Mo.

[0016] The method for preparing a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet (EUV) photolithography mask protective film provides a self-supporting single-walled carbon nanotube EUV photolithography mask protective film with adjustable EUV transmittance. The transmittance is related to the thickness of the single-walled carbon nanotube film. At a wavelength of 13.5 nm, the EUV transmittance of the 7~11 cm × 14~16 cm self-supporting film is >95%.

[0017] The design concept of this invention is: This invention employs floating catalyst chemical vapor deposition to grow SWCNTs. By improving catalyst lifetime and extending SWCNT growth time, controllable growth of SWCNTs with large aspect ratios is achieved. The strong van der Waals forces of ultra-high aspect ratio SWCNTs are utilized, combined with in-situ molecular-level assembly of interlocking and entangled thin films. Based on the difference in van der Waals forces between the SWCNT film and the target frame and collection substrate, as well as the excellent toughness of the film itself, the film is transferred to the target hollow frame, realizing its application as a protective film for extreme ultraviolet lithography masks.

[0018] This invention uses Se as a growth promoter for SWCNTs. Compared to traditional S growth promoters, Se's high-temperature stability significantly extends catalyst lifetime and promotes SWCNT nucleation. Simultaneously, by employing a reactor with a long isothermal zone (0.9~1m), the SWCNT growth time is extended, resulting in longer individual SWCNTs and achieving an aspect ratio >50000 and a crystallinity of I. G / I D SWCNTs with a ratio of G peak intensity to D peak intensity in Raman spectra measured at 532 nm laser wavelength > 200 can be grown in a controlled manner.

[0019] The advantages and beneficial effects of this invention are: 1. This invention enables the controllable fabrication of large aspect ratio SWCNT thin films. The prepared films can achieve self-support in areas of 7×16cm and 11cm×14cm, meeting the requirements of full-size extreme ultraviolet lithography mask protective films and overcoming the limitations of existing technologies for small-size self-support.

[0020] 2. The large-area, self-supporting SWCNT thin film obtained by this invention has a transmittance T at a wavelength of 13.5 nm. 13.5 It is adjustable and can exceed 95% while ensuring a self-supporting thickness of 7×16 cm or 11cm×14cm.

[0021] 3. The present invention has high crystallinity (I) G / I D The SWCNT with a length-to-diameter ratio of >200 and a length-to-diameter ratio of >50000 gives the film extremely strong intertube forces, and there is no tearing or delamination during the transfer process. It can be completely peeled off and transferred to hollow frames of different materials (such as metal, quartz, glass, polymer, etc.).

[0022] 4. The method for preparing large-area, self-supporting SWCNT thin films developed in this invention has a simple film preparation and transfer process. The large aspect ratio single-walled carbon nanotubes enable the thin films composed of them to achieve large-area self-support and reduce extreme ultraviolet light absorption rate. It is expected to play an important role in the field of extreme ultraviolet lithography protective films, promote the development of high-power extreme ultraviolet lithography technology, and is suitable for next-generation high-power extreme ultraviolet lithography mask protective films. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the fabrication of a large-area, self-supporting SWCNT thin film. In the diagram, 1 is the syringe, 2 is the growth catalyst and promoter precursor, 3 is the tube furnace, 4 is the catalyst particles, 5 is the grown single-walled carbon nanotubes, and 6 is the collector.

[0024] Figure 2 (a) Optical photograph and (b) Transmission electron microscope photograph of a high aspect ratio SWCNT film collected on a microporous filter membrane.

[0025] Figure 3 (a) Optical photograph and (b) Scanning electron microscope image of SWCNT film peeled off from microporous filter membrane.

[0026] Figure 4 Optical photographs of a high aspect ratio SWCNT film transferred onto a stainless steel frame with a through-hole of 7cm × 16cm.

[0027] Figure 5 (a) Optical photograph of the SWCNT film peeled off from the microporous filter membrane of Comparative Example 1 sample, (b) Transmission electron microscope photograph of Comparative Example 1 sample, (c) Typical scanning electron microscope photograph of Comparative Example 1 sample. Detailed Implementation

[0028] like Figure 1 As shown, the large-area, self-supporting SWCNT thin film preparation system of the present invention mainly includes: a syringe 1, a growth catalyst and promoter precursor 2, a tube furnace 3, catalyst particles 4, grown single-walled carbon nanotubes 5, and a filter membrane 6 for collecting carbon nanotube films. The growth catalyst and promoter precursor 2 required for growing SWCNTs are injected into one end of the tube furnace 3 through the syringe 1. Under the action of high temperature and hydrogen carrier gas, the growth catalyst and promoter precursor 2 form Se-doped catalyst particles 4, and dissolve carbon, precipitate carbon, and nucleate and grow SWCNTs. SWCNTs flow and grow continuously in the high-temperature zone with the carrier gas, and finally flow out of the high-temperature zone with the carrier gas, stopping growth. The grown single-walled carbon nanotubes 5 are intercepted by the collector 6 (the filter membrane used to collect carbon nanotubes) to form a thin film.

[0029] The specific steps for preparing the large-area, self-supporting SWCNT thin film with high extreme ultraviolet light transmittance are as follows: (1) Under argon protection, the tube furnace 3 is first heated to the target temperature, and then the carrier gas hydrogen and gaseous carbon source are introduced from one end of the tube furnace 3. (2) Carried by the carrier gas hydrogen, the solution containing the catalyst and growth promoter precursor is pushed into the reactor body and volatilized at the front end of the high temperature zone to form Se-doped iron catalyst particles. (3) SWCNTs are carried by the carrier gas through the high temperature zone and continue to grow with the supply of carbon source, and finally exit the high temperature zone with the carrier gas.

[0030] (4) After preparation, stop the supply of carrier gas, carbon source and catalyst, and cool the reactor to room temperature under the protection of argon flow.

[0031] This invention, in the process of growing SWCNTs using floating catalyst chemical vapor deposition, utilizes a novel Se growth promoter combined with a long isothermal zone tube furnace to achieve controlled preparation and film collection of SWCNTs with large aspect ratios (>50000) under optimized conditions. The single-walled carbon nanotube films self-assembled from single-walled carbon nanotubes with aspect ratios >50000 exhibit excellent mechanical properties and flexibility. The prepared SWCNT films can not only achieve large-area self-support (e.g., 11 cm × 14 cm frames, 7 cm × 16 cm frames), but also have extremely high and adjustable EUV transmittance (reaching over 95%). The prepared films are expected to serve as ideal protective films for next-generation high-power EUV lithography masks.

[0032] The present invention will now be described in further detail with reference to embodiments and accompanying drawings.

[0033] Example 1

[0034] In this embodiment, a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film is implemented using the following steps: (1) Under the protection of argon at 3000 sccm, the temperature of the reactor with a constant temperature zone of 1 meter is first raised to 1200℃. Ferrocene and selenophene (weight ratio of 8:1) are used as catalyst and growth promoter precursors, respectively, and ethylene is used as carbon source to grow SWCNTs. The catalyst and promoter precursor are carried into the high temperature zone of the tube furnace by hydrogen carrier gas to form Se-doped iron catalyst particles. SWCNTs flow with the carrier gas and continue to grow under the supply of carbon source. The grown SWCNTs flow out of the high temperature zone with the carrier gas and are intercepted by the collector (microporous filter membrane), self-assembled in situ into a network structure, and deposited in the collector to form a thin film.

[0035] (2) For example Figure 2 As shown in Figure a, an optical photograph of the SWCNT tube film collected at the tail end of the tube furnace is shown. The size of the collected SWCNT film can be adjusted by the size of the collector; as shown in Figure a. Figure 2 As shown in b, the morphology of the grown SWCNTs was observed using a transmission electron microscope. The grown CNTs consist of only a single layer of tube wall, which is SWCNT. The average diameter is about 1.8 nm and there is no catalyst residue.

[0036] (3) such as Figure 3 As shown in Figure a, the film-forming properties of the membrane were verified by simply grasping it with tweezers. The membrane could be easily peeled off from the filter membrane, and the membrane as a whole showed no delamination or tearing. Figure 3As shown in b, the length of the SWCNT bundle was observed using a scanning electron microscope. It can be seen that the beginning and end of the SWCNT bundle are difficult to trace under the scanning electron microscope, but the length of the SWCNT bundle can be seen from the comparison with the scale length. It can be seen that the length of the SWCNT bundle is >120 micrometers. Combined with the diameter of the SWCNT tube is about 1.8 nm, its aspect ratio is calculated to be greater than 65000.

[0037] (4) Due to the extremely high aspect ratio and high purity of the grown SWCNTs, the films formed have excellent film-forming properties. Therefore, they can be directly transferred to hollow frames using van der Waals force differences, and transfer to frames of different shapes and sizes can be achieved. For example... Figure 4 As shown, the largest suspended size currently achieved is 7 cm × 16 cm for self-supporting film fabrication, meeting the requirements for full-size extreme ultraviolet lithography mask protective films; and it is expected that the size can be further increased by improving the collection device.

[0038] (5) The transmittance of a 7 cm × 16 cm film with a transmittance of 90% at a wavelength of 550 nm was tested at a wavelength of 13.5 nm, and the transmittance was 96%.

[0039] Example 2

[0040] In this embodiment, a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film is implemented using the following steps: (1) Step 1 is the same as step (1) in Example 1, except that a reactor with a constant temperature zone length of 0.9 meters is used, and the weight ratio of ferrocene and selenophene is 10:1.

[0041] (2) The morphology of the grown SWCNTs was observed using a transmission electron microscope. The grown CNTs consisted of only a single-layer tube wall, which is SWCNT, and its average diameter was 1.9 nm. The length of the SWCNT tube bundle was observed using a scanning electron microscope. The length of the SWCNT tube bundle was >100 micrometers. Combined with the diameter of the single-walled carbon nanotubes, its aspect ratio was calculated to be >52000.

[0042] (3) The film can be transferred to frames of different shapes and sizes. Currently, the largest suspended size can reach 11 cm × 14 cm for the preparation of self-supporting film. The transmittance of the 11 cm × 14 cm film with a transmittance of 90% at a wavelength of 550 nm was tested at a wavelength of 13.5 nm, and its transmittance was 97%.

[0043] Example 3

[0044] In this embodiment, a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film is implemented using the following steps: (1) Same as step (1) in Example 1, except that a reactor with a constant temperature zone length of 0.9 meters is used and the weight ratio of ferrocene and selenophene is 12:1.

[0045] (2) The morphology of the grown SWCNTs was observed using a transmission electron microscope. The grown CNTs consisted of only a single-walled tube, which is SWCNT; its average diameter was 2 nm. The length of the SWCNT bundles was observed using a scanning electron microscope. The length of the SWCNT bundles was >100 micrometers. Combined with the diameter of the single-walled carbon nanotubes being about 2 nm, its aspect ratio was calculated to be >50000.

[0046] (3) The film can be transferred to frames of different shapes and sizes. Currently, the largest suspended size can reach 11 cm × 14 cm for the preparation of self-supporting films. The transmittance of the 11 cm × 14 cm film with a transmittance of 90% at a wavelength of 550 nm was tested at a wavelength of 13.5 nm, and its transmittance was 94%.

[0047] Comparative Example 1 In this comparative example, a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film is produced using the following specific steps: (1) Same as step (1) in Example 1, except that a reaction furnace with a constant temperature zone length of 0.5 meters is used.

[0048] (2) For example Figure 5 As shown in Figure a, the optical photograph of the prepared thin film shows that it is difficult to peel off completely when using tweezers, leaving residue on the filter membrane, indicating poor film-forming properties. Figure 5 As shown in b, the transmission electron microscope image revealed that it was composed of SWCNTs with an average diameter of 2 nm and contained residual catalyst impurities; Figure 5 As shown in Figure c, the scanning electron microscope image reveals that the length of the single-walled carbon nanotubes / bundles is approximately 30–40 micrometers. Considering the average diameter of the single-walled carbon nanotubes is approximately 2 nm, their aspect ratio is calculated to be approximately 15,000–20,000.

[0049] (3) The film can be transferred to a circular frame with a through-hole diameter of 1 cm, but when the through-hole diameter is increased to 3 cm, it is difficult to achieve self-support. The transmittance of a 1 cm diameter film with a transmittance of 90% at 550 nm wavelength was tested at 13.5 nm wavelength, and its transmittance was 93%.

[0050] Comparative Example 2 In this comparative example, a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film is produced using the following specific steps: (1) Same as step (1) in Example 1, using sulfur as a growth promoter.

[0051] (2) The prepared film was difficult to peel off completely from the filter membrane, indicating poor film-forming properties. Transmission electron microscopy revealed that it was composed of SWCNTs with an average diameter of 1.8 nm and contained a large amount of catalyst impurities; scanning electron microscopy showed that the length of the SWCNT bundle was approximately 10-20 micrometers. Based on the average diameter of the SWCNTs of approximately 1.8 nm, its aspect ratio was calculated to be approximately 5500-11000.

[0052] (3) The film is difficult to support itself on the hollow frame and is prone to tearing and delamination during the transfer process, indicating that its mechanical strength is insufficient.

[0053] The results of the examples and comparative examples show that by using floating catalyst chemical vapor deposition to grow SWCNTs, the growth of SWCNTs with large aspect ratios can be controlled by improving catalyst lifetime and extending carbon nanotube growth time. The strong van der Waals forces of ultra-high aspect ratio SWCNTs allow for in-situ molecular assembly into interlocking SWCNT films. Furthermore, by utilizing the difference in van der Waals forces between SWCNTs and the target framework and the collecting substrate, as well as the inherent toughness of the film, the film can be transferred to hollow frameworks of different sizes and shapes. This enables the preparation and transfer of full-size SWCNT films that meet the application requirements of extreme ultraviolet (EUV) lithography mask protective films. This invention solves the key bottleneck problem currently faced by domestic and international manufacturers in producing ultra-thin, large-area, self-supporting SWCNT EUV lithography mask protective films.

[0054] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film, characterized in that, Single-walled carbon nanotubes (SWNTs) are grown using a floating catalyst chemical vapor deposition method. By extending the growth time of SWNTs, the length and aspect ratio of the SWNTs are increased. Taking advantage of the flexibility and strong van der Waals forces of the ultra-long SWNTs, they are directly self-assembled into interlocking and entangled high-strength and tough SWNT films during the growth process. These high-strength and tough SWNT films are then transferred to target substrates or hollow frames of different sizes and shapes to serve as protective films for self-supporting extreme ultraviolet lithography masks. The catalyst lifetime was improved by using Se growth promoter, and the growth time of single-walled carbon nanotubes was extended by extending the length of the isothermal zone in the floating catalyst chemical vapor deposition furnace. The length of the isothermal zone was 0.9~1 meter. In the floating catalyst chemical vapor deposition method, ferrocene is used as the catalyst precursor and ethylene is used as the carbon source. The weight percentage of the catalyst precursor to the Se promoter precursor is 8:1 to 12:

1.

2. The method for preparing a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film according to claim 1, characterized in that, The prepared single-walled carbon nanotubes refer to carbon nanotubes that are observed to consist of only a single layer of tube wall in transmission electron microscopy images. Their diameter is 1.6~2.1nm, with more than 90% being 1.8~2.0nm, length >100μm, and aspect ratio is 45000~70000, with more than 90% being >50000.

3. The method for preparing a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film according to claim 2, characterized in that, The prepared single-walled carbon nanotubes exhibit extremely high crystallinity, and their Raman spectra are... G / I D >200.

4. The method for preparing a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film according to claim 3, characterized in that, The prepared single-walled carbon nanotubes are formed by intertwining and overlapping of single-walled carbon nanotubes with large aspect ratio and high crystallinity. They have extremely strong inter-tube forces and do not require substrate support. They can be transferred to target substrates or hollow frames of various sizes and shapes to achieve large-area self-support, with a suspended area of ​​7~11 cm × 14~16 cm.

5. The method for preparing a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film according to claim 1 or 4, characterized in that, The single-walled carbon nanotube film on the collector is transferred to a suspended target substrate or hollow frame by utilizing the difference in van der Waals forces. The target substrate or hollow frame is made of metal, quartz, glass, polycrystalline silicon, alumina, graphite, indium tin oxide, polyethylene terephthalate, or polydimethylsiloxane.

6. The method for preparing a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film according to claim 5, characterized in that, The material of the target substrate or hollow frame includes metals such as Cu, Ti, Fe, Pt, Au, Ni, or Mo.

7. The method for preparing a large-area, self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film according to claim 1, characterized in that, The prepared self-supporting single-walled carbon nanotube extreme ultraviolet lithography mask protective film has adjustable extreme ultraviolet light transmittance, which is related to the thickness of the single-walled carbon nanotube film. At a wavelength of 13.5 nm, the extreme ultraviolet transmittance of the 7~11 cm×14~16 cm self-supporting film is >95%.

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