Protective films, protective film assemblies, carbon nanotube webs and methods of making the same, carbon nanotube films, and carbon nanotube wires and methods of making the same

Abstract

Provided is a technology capable of realizing a protective film made of carbon nanotubes and having excellent in-plane uniformity of transmittance. A protective film (12) includes a plurality of first carbon nanotubes (1200a) each extending along a first direction (D1) and arranged along a radial direction, and a plurality of second carbon nanotubes (1200b) each extending along a second direction (D2) intersecting the first direction (D1) and arranged along the radial direction.

Description

TECHNICAL FIELD

[0001] The present application relates to pellicles. BACKGROUND

[0002] The minimum size of a pattern that can be formed by a lithography technique depends on the wavelength of light used for exposure. By using light with a shorter wavelength in exposure, the minimum size can be reduced.

[0003] Hitherto, an ArF excimer laser with a wavelength of 193 nm has been used for exposure. In recent years, there is an increasing demand for a lithography technique capable of forming a finer pattern, and an extreme ultraviolet (EUV light) with a wavelength of 13.5 nm is being used.

[0004] A pellicle is used to prevent dust and the like from adhering to a photomask or a reticle. Since EUV light is easily absorbed by various substances, in extreme ultraviolet lithography (EUVL), a pellicle using polysilicon having a low absorption rate for EUV light is being developed.

[0005] However, a pellicle made of polysilicon has poor heat resistance. Therefore, a pellicle composed of a carbon material such as graphene, a carbon nanotube, or the like has attracted attention (see Patent Documents 1 to 3).

[0006] PRIOR ART DOCUMENTS

[0007] PATENT DOCUMENTS

[0008] Patent Document 1: Japanese Patent Application Publication No. 2018-194838

[0009] Patent Document 2: Japanese Patent Application Publication No. 2018-194840

[0010] Patent Document 3: International Publication No. 2018 / 008594 SUMMARY

[0011] A pellicle containing a carbon nanotube can have insufficient in-plane uniformity of transmittance due to uneven distribution of the carbon nanotube.

[0012] An object of the present application is to provide a technology capable of realizing a pellicle composed of a carbon nanotube and having excellent in-plane uniformity of transmittance.

[0013] According to a first aspect of the present application, there is provided a pellicle comprising: a plurality of first carbon nanotubes each extending along a first direction and arranged along a radial direction, and a plurality of second carbon nanotubes each extending along a second direction intersecting the first direction and arranged along the radial direction.

[0014] According to another aspect of the present application, there is provided the protective film according to any one of the above aspects, wherein at least one of the first carbon nanotube network and the second carbon nanotube network is provided with a plurality of pores.

[0015] According to another aspect of the present application, there is provided the protective film according to any one of the above aspects, wherein at least one of the first carbon nanotube network and the second carbon nanotube network is provided with a plurality of pores.

[0016] According to another aspect of the present application, there is provided the protective film according to any one of the above aspects, wherein at least one of the first carbon nanotube network and the second carbon nanotube network is provided with a plurality of pores.

[0017] According to another aspect of the present application, there is provided the protective film according to any one of the above aspects, wherein the plurality of pores have a maximum diameter of 100 nm or less.

[0018] According to another aspect of the present application, there is provided the protective film according to any one of the above aspects, wherein at least one of the first carbon nanotube network and the second carbon nanotube network is provided with a plurality of pores.

[0019] According to a second aspect of the present application, there is provided a protective film comprising: a plurality of first carbon nanotube lines each made of a plurality of first carbon nanotubes and each extending along a first direction, and a plurality of second carbon nanotube lines each made of a plurality of second carbon nanotubes and each extending along a second direction intersecting the first direction, the plurality of first carbon nanotube lines and the plurality of second carbon nanotube lines forming a fabric.

[0020] According to another aspect of the present application, there is provided the protective film according to any one of the above aspects, wherein the distance between adjacent ones of the plurality of first carbon nanotube lines and the maximum distance between adjacent ones of the plurality of second carbon nanotube lines is 100 nm or less.

[0021] According to another aspect of the present application, there is provided the protective film according to any one of the above aspects, wherein one or more of the plurality of first carbon nanotube lines and the plurality of second carbon nanotube lines has a diameter that varies along a length direction.

[0022] According to another aspect of the present application, there is provided the protective film according to any one of the above aspects, having a thickness of 500 nm or less.

[0023] According to a third aspect of the present application, there is provided a protective film assembly including the protective film according to any one of the above aspects, and a frame supporting the protective film.

[0024] According to a fourth aspect of the present application, there is provided a carbon nanotube network including a plurality of carbon nanotubes each extending along one direction and arranged along a radial direction, and provided with a plurality of holes.

[0025] According to a fifth aspect of the present application, there is provided a carbon nanotube film including a first carbon nanotube network including a plurality of first carbon nanotubes each extending along a first direction and arranged along a radial direction, and a second carbon nanotube network including a plurality of second carbon nanotubes each extending along a second direction intersecting the first direction and arranged along a radial direction, at least one of the first carbon nanotube network and the second carbon nanotube network being provided with a plurality of holes.

[0026] According to a sixth aspect of the present application, there is provided a carbon nanotube line made of a plurality of carbon nanotubes, and having a diameter varying along a length direction.

[0027] According to a seventh aspect of the present application, there is provided a method of manufacturing a carbon nanotube network, including: preparing a carbon nanotube array composed of a plurality of carbon nanotubes each extending from a support surface and having one or more holes or recesses; and pulling out the carbon nanotubes from an end surface of the carbon nanotube array in a network shape.

[0028] According to an eighth aspect of the present application, there is provided a method of manufacturing a carbon nanotube line, including: preparing a carbon nanotube array composed of a plurality of carbon nanotubes each extending from a support surface and having one or more holes or recesses; and pulling out the carbon nanotubes from an end surface of the carbon nanotube array in a line shape.

[0029] According to the present application, it is possible to provide a technology capable of realizing a protective film made of carbon nanotubes and having excellent in-plane uniformity of transmittance. BRIEF DESCRIPTION OF DRAWINGS

[0030] [ Figure 1 ] is a cross-sectional view schematically showing a protective film assembly according to an embodiment of the present application mounted on a photomask.

[0031] [ Figure 2 ] is a perspective view schematically showing one example of a protective film usable for the protective film assembly of Figure 1 .

[0032] [ Figure 3 ] is a perspective view schematically showing one example of a carbon nanotube array usable for manufacturing the protective film of Figure 2 .

[0033] [ Figure 4FIG. 1 is a perspective view schematically showing one example of a manufacturing method of a carbon nanotube web.

[0034] [ Figure 5 FIG. 2 is a perspective view schematically showing one modification of a carbon nanotube array.

[0035] [ Figure 6 FIG. 3 is a plan view schematically showing one example of a carbon nanotube web obtained using the carbon nanotube array of Figure 5

[0036] [ Figure 7 FIG. 4 is a plan view schematically showing other examples of a protective film that can be used in the protective film assembly of Figure 1

[0037] [ Figure 8 FIG. 5 is a view schematically showing one example of a carbon nanotube line that can be used in the protective film of Figure 7

[0038] [ Figure 9 FIG. 6 is a perspective view schematically showing one example of a manufacturing method of a carbon nanotube line.

[0039] [ Figure 10 FIG. 7 is a view schematically showing a carbon nanotube line involved in one modification. DETAILED DESCRIPTION

[0040] Embodiments of the present application will be described below with reference to the accompanying drawings. The embodiments described below embody any of the above aspects more specifically. Note that, in the drawings referred to below, the same reference symbols are assigned to elements having the same or similar functions, and redundant description is omitted. Furthermore, in each drawing, the dimensional ratio and the shape can be different from those of the actual one.

[0041] Figure 1 FIG. 8 is a cross-sectional view schematically showing a protective film assembly involved in one embodiment of the present application mounted on a photomask.

[0042] In Figure 1 , the photomask 2 on which the protective film assembly 1 is mounted is a reflective photomask for EUV lithography. The protective film assembly 1 can also be mounted on other photomasks.

[0043] The photomask 2 includes a substrate 21, a multilayer reflective film 22, a cover film 23, and an absorbing layer 24.

[0044] The substrate 21 has a flat surface. The substrate 21 is made of, for example, a material having a small thermal expansion rate such as synthetic quartz.

[0045] ​​​A multilayer reflective film 22 is provided on the aforementioned surface of the substrate 21. The multilayer reflective film 22 includes two or more layers having different refractive indexes with respect to EUV light. The multilayer reflective film 22 is designed to exhibit high reflectivity with respect to EUV light by repeated reflection interference, and to exhibit low reflectivity with respect to other light.

[0046] Here, the multilayer reflective film 22 includes reflection layers 22a and 22b having different refractive indexes with respect to EUV light and alternately laminated. With respect to the reflection layers 22a and 22b, for example, one is made of silicon and the other is made of molybdenum. Note that in the case where the multilayer reflective film 22 includes three or more combinations of the reflection layers 22a and 22b, the reflection layers 22a and 22b are not necessarily alternately laminated. Figure 1 Here, the multilayer reflective film 22 includes three combinations of the reflection layers 22a and 22b, but generally includes more combinations, for example, about 40 combinations.

[0047] A cover film 23 is provided on the multilayer reflective film 22. The cover film 23 functions to protect the multilayer reflective film 22 from etchants or cleaning agents at the time of patterning for obtaining the absorption layer 24 or at the time of cleaning the photomask 2. The cover film 23 is, for example, composed of ruthenium.

[0048] The absorption layer 24 is provided on the cover film 23. The absorption layer 24 is provided with an opening portion of a pattern corresponding to an exposed pattern of a photoresist layer on a semiconductor wafer.

[0049] The absorption layer 24 is a layer composed of a material exhibiting high absorbance with respect to EUV light. The absorption layer 24 is, for example, composed of tantalum, indium oxide, tellurium oxide, or tin telluride.

[0050] The protective film assembly 1 is attached to the photomask 2. Here, the protective film assembly 1 prevents dust and the like from adhering to the reflecting surface of the photomask 2. Note that in the case where the photomask is of a transmissive type, the protective film assembly 1 can be attached to both surfaces of the photomask.

[0051] The protective film assembly 1 includes a frame 11 and a protective film 12.

[0052] The frame 11 is attached to the photomask 2 via an adhesive not shown. The frame 11 functions as a spacer that separates the protective film 12 from the photomask 2. The frame 11 is, for example, made of aluminum.

[0053] The protective film 12 is a film exhibiting high transmittance with respect to an exposure light source (here, EUV light). The protective film 12 is supported by the frame 11 in a manner of facing the photomask 2 with the frame 11 interposed. Specifically, a peripheral portion of the protective film 12 is fixed to the frame 11, for example, by an adhesive.

[0054] The protective film 12 is a carbon nanotube film. Specifically, the protective film 12 includes a plurality of first carbon nanotubes each extending along a first direction and arranged along a radial direction, and a plurality of second carbon nanotubes each extending along a second direction intersecting the first direction and arranged along the radial direction. According to one example, the protective film 12 is composed of only the first and second carbon nanotubes.

[0055] Figure 2 A perspective view schematically showing one example of a protective film that can be used in a protective film assembly of the present application. Figure 1

[0056] Figure 2 The protective film 12 includes a first carbon nanotube network 121a and a second carbon nanotube network 121b. The first carbon nanotube network 121a overlaps the second carbon nanotube network 121b.

[0057] The first carbon nanotube network 121a is formed of a plurality of first carbon nanotubes 1200a. The first carbon nanotubes 1200a each extend along a first direction D1 and are arranged along a radial direction.

[0058] The second carbon nanotube network 121b is formed of a plurality of second carbon nanotubes 1200b. The second carbon nanotubes 1200b each extend along a second direction D2 intersecting the first direction D1 and are arranged along the radial direction. According to one example, the first direction D1 is orthogonal to the second direction D2. The first direction D1 and the second direction D2 can also intersect obliquely.

[0059] Note that, in the first carbon nanotube network 121a, there are inevitably carbon nanotubes extending along a direction other than the first direction D1, or curved carbon nanotubes. Similarly, in the second carbon nanotube network 121b, there are inevitably carbon nanotubes extending along a direction other than the second direction D2, or curved carbon nanotubes.

[0060] Further, in the first carbon nanotube network 121a, the first carbon nanotubes 1200a are depicted as a monomolecular film in which the first carbon nanotubes 1200a are arranged only in the in-plane direction without being stacked in the thickness direction, but the first carbon nanotubes 1200a can be arranged in the in-plane direction while being stacked in the thickness direction. Similarly, in the second carbon nanotube network 121b, the second carbon nanotubes 1200b are depicted as a monomolecular film in which the second carbon nanotubes 1200b are arranged only in the in-plane direction without being stacked in the thickness direction, but the second carbon nanotubes 1200b can be arranged in the in-plane direction while being stacked in the thickness direction. Figure 2 Figure 2 Further, in the first carbon nanotube network 121a, the first carbon nanotubes 1200a are depicted as a monomolecular film in which the first carbon nanotubes 1200a are arranged only in the in-plane direction without being stacked in the thickness direction, but the first carbon nanotubes 1200a can be arranged in the in-plane direction while being stacked in the thickness direction. Similarly, in the second carbon nanotube network 121b, the second carbon nanotubes 1200b are depicted as a monomolecular film in which the second carbon nanotubes 1200b are arranged only in the in-plane direction without being stacked in the thickness direction, but the second carbon nanotubes 1200b can be arranged in the in-plane direction while being stacked in the thickness direction.

[0061] Further, in the first carbon nanotube network 121a, the first carbon nanotubes 1200a are depicted as a monomolecular film in which the first carbon nanotubes 1200a are arranged only in the in-plane direction without being stacked in the thickness direction, but the first carbon nanotubes 1200a can be arranged in the in-plane direction while being stacked in the thickness direction. Similarly, in the second carbon nanotube network 121b, the second carbon nanotubes 1200b are depicted as a monomolecular film in which the second carbon nanotubes 1200b are arranged only in the in-plane direction without being stacked in the thickness direction, but the second carbon nanotubes 1200b can be arranged in the in-plane direction while being stacked in the thickness direction. Figure 2 Figure 2 ​​​In the embodiment, the first carbon nanotube network 121a has the same diameter as the second carbon nanotube network 121b, but they can have different diameters. Figure 2 In the embodiment, the first carbon nanotube network 121a has the same diameter as the second carbon nanotube network 121b, but they can have different diameters.

[0062] In the embodiment, the first carbon nanotube network 121a has the same diameter as the second carbon nanotube network 121b, but they can have different diameters. Figure 3 In the embodiment, the first carbon nanotube network 121a is in contact with the second carbon nanotube network 121b, but they can be separated from each other. That is, the first carbon nanotube 1200a can be in contact with the second carbon nanotube 1200b, or they can be separated from each other.

[0063] The protective film 12 can include three or more carbon nanotube networks. In this case, the protective film 12 can include two or more first carbon nanotube networks 121a and one or more second carbon nanotube networks 121b. Alternatively, the protective film 12 can include one or more first carbon nanotube networks 121a and two or more second carbon nanotube networks 121b. Alternatively, the protective film 12 can include one or more first carbon nanotube networks 121a, one or more second carbon nanotube networks 121b, and one or more carbon nanotube networks having the same structure as them except that the length direction of the carbon nanotubes is different.

[0064] The thickness of the protective film 12 is preferably 500 nm or less. When the protective film 12 is thick, the transmittance of the exposure light source (EUV light in this case) decreases. The thickness of the protective film 12 is preferably 10 nm or more. When the protective film 12 is thin, the mechanical strength decreases, and the possibility of dust and the like penetrating the protective film 12 increases.

[0065] The protective film 12 preferably does not allow dust and the like having a diameter of 30 nm or more to penetrate. That is, the gap between the carbon nanotubes in the protective film 12 is preferably such that dust and the like having a diameter of 30 nm or more do not penetrate.

[0066] The protective film 12 described above can be manufactured, for example, by the following method.

[0067] Figure 2 A perspective view schematically showing one example of a carbon nanotube array that can be used to manufacture the protective film of Figure 4 A perspective view schematically showing one example of a method of manufacturing a carbon nanotube network. Figure 3 A perspective view schematically showing one example of a method of manufacturing a carbon nanotube network.

[0068] In manufacturing the protective film 12 described above, first, the structure shown in FIG. 1 is prepared. Figure 3 The structure shown in FIG. 1 includes a substrate 31, a catalyst layer 32, and a carbon nanotube array 120. Figure 3

[0069] ​The substrate 31 has a flat surface. The substrate 31 is, for example, a silicon substrate, a glass substrate, or a sapphire substrate.

[0070] A catalyst layer 32 is disposed on the surface of the substrate 31. The catalyst layer 32 is made of metals such as iron, nickel, and cobalt.

[0071] A substrate layer may be sandwiched between the substrate 31 and the catalyst layer 32. The substrate layer may be made of, for example, aluminum nitride, aluminum oxide, or silicon oxide.

[0072] The carbon nanotube array 120 is an assembly of many carbon nanotubes 1200. These carbon nanotubes 1200 extend on the catalyst layer 32 from the supporting surface that serves as the surface of the catalyst layer 32 in a manner substantially perpendicular to that surface. It should be noted that the term "carbon nanotube array" is synonymous with the term "carbon nanotube forest".

[0073] The carbon nanotube 1200 can be a single-walled carbon nanotube, a multi-walled carbon nanotube, or a combination thereof. Furthermore, the carbon nanotube 1200 can be any of the following: armchair-shaped, zigzag-shaped, chiral, or a combination of two or more of these.

[0074] The length of carbon nanotubes 1200 ranges from, for example, 0.1 mm to 5 mm. It should be noted that... Figure 4 The length-to-diameter ratio of the carbon nanotubes 1200 in the image is much smaller than the actual ratio.

[0075] Carbon nanotube arrays 120 can be fabricated, for example, by CVD (Chemical Vapor Deposition) such as Super Growth CVD (water-assisted CVD).

[0076] Next, as Figure 4 As shown, carbon nanotubes 1200 are pulled out in a mesh-like pattern from the end face of the carbon nanotube array 120. Van der Waals forces act on radially adjacent carbon nanotubes 1200. Therefore, for example, when the end face or a portion thereof of the carbon nanotube array 120 is held and stretched away from the carbon nanotube array 120, the carbon nanotubes 1200 are pulled out from the carbon nanotube array 120 one after another. Thus, a carbon nanotube mesh 121 can be obtained without the use of adhesives or the like.

[0077] It should be noted that the carbon nanotube network 121 obtained in this way is a self-standing membrane that can be processed independently. In addition, in this carbon nanotube network 121, most of the carbon nanotubes 1200 have a shape that extends along the direction in which they are pulled out.

[0078] Next, multiple carbon nanotube networks 121 are overlapped in such a way that the carbon nanotubes 1200 they contain intersect in the longitudinal direction. Then, the laminate is pressed. This pressing can be performed on the entire laminate or on only one or more parts. Alternatively, pressing can be omitted.

[0079] A carbon nanotube membrane was obtained as described above. The carbon nanotube membrane thus obtained can be used as the aforementioned protective membrane 12.

[0080] The protective film 12 exhibits excellent in-plane uniformity of transmittance. This will be explained below.

[0081] Carbon nanotube films can also be obtained, for example, by forming a coating from a dispersion of carbon nanotubes and removing the dispersion medium from the coating. However, according to this method, carbon nanotube aggregation occurs during the removal of the dispersion medium. Therefore, in the carbon nanotube film obtained by this method, portions where carbon nanotubes exist at high density and portions where carbon nanotubes exist at low density are easily formed.

[0082] Furthermore, in carbon nanotube films obtained from carbon nanotube dispersions, most carbon nanotubes have tortuous and / or buckled shapes. Therefore, the carbon nanotube films obtained by this method contain a large number of intersecting carbon nanotubes. EUV light absorption is caused by these intersecting carbon nanotubes; the more intersecting carbon nanotubes, the more EUV light is absorbed. Therefore, it is believed that the amount of EUV light absorbed differs between the intersecting and non-intersecting carbon nanotube regions. Moreover, these intersecting regions are not uniformly distributed, but rather non-uniformly distributed.

[0083] Therefore, the in-plane uniformity of the transmittance of carbon nanotube films obtained from carbon nanotube dispersions is insufficient.

[0084] In contrast, in the carbon nanotube network 121 described above, most of the carbon nanotubes 1200 have a shape obtained by extending along the direction in which they are pulled out. That is, the carbon nanotubes 1200 each extend along one direction and are arranged radially.

[0085] Such a structure cannot be obtained by using a dispersion of carbon nanotubes, but it can be achieved by referring to... Figure 5 The method described is used to obtain the carbon nanotubes 1200. Therefore, the carbon nanotubes 1200 are uniformly distributed in the carbon nanotube network 121. Furthermore, the number of intersections of the carbon nanotubes 1200 in the carbon nanotube network 121 is not large. Therefore, when the carbon nanotube network 121 is overlapped such that the carbon nanotubes 1200 they contain intersect in the longitudinal direction, the intersections of the carbon nanotubes 1200 can be uniformly distributed.

[0086] Therefore, the in-plane uniformity of the transmittance of the protective film 12 is excellent.

[0087] The protective film 12 can be variously modified.

[0088] Figure 6 A perspective view for schematically showing a modification example of the carbon nanotube array. Figure 5 A plan view for schematically showing one example of the carbon nanotube network obtained using Figure 5 the carbon nanotube array.

[0089] Figure 3 The carbon nanotube array 120 provided with the plurality of holes or recesses 120H is identical to the carbon nanotube array 120 described with reference to Figure 3 except for this.

[0090] The holes or recesses 120H are, for example, through holes. In this case, the carbon nanotube array 120 provided with the holes or recesses 120H can be obtained, for example, by previously opening the catalyst layer 32 described with reference to Figure 4 at positions corresponding to the holes or recesses 120H.

[0091] Alternatively, the holes or recesses 120H are blind holes, that is, recesses provided on the surface of the carbon nanotube array 120 and having a bottom surface composed of the leading ends of the plurality of carbon nanotubes 1200. In this case, the carbon nanotube array 120 provided with the holes or recesses 120H can be obtained, for example, by manufacturing the carbon nanotube array 120 shown in FIG. 12, forming a mask layer opened at positions corresponding to the holes or recesses 120H thereon, and then etching the carbon nanotubes 1200 at the positions of these openings. Figure 4

[0092] Thus, the carbon nanotube array 120 provided with the holes or recesses 120H is prepared, and then, except for using this carbon nanotube array 120, the carbon nanotube network 121 is obtained by the same method as described with reference to Figure 6 As a result of the carbon nanotube array 120 being provided with the holes or recesses 120H, the carbon nanotube network 121 thus obtained has a plurality of holes 121H as shown in FIG. 13. The maximum diameter of these holes 121H is preferably 100 nm or less. Figure 7 These holes 121H can be formed at an arbitrary position with an arbitrary size by appropriately setting the positions, sizes, and the speed of pulling out the carbon nanotube network 121 of the holes or recesses 120H provided in the carbon nanotube array 120. Therefore, when the carbon nanotube network 121 provided with these holes 121H is used in the protective film 12, for example, the transmittance of the protective film 12 can be improved without adversely affecting the patterning using the photomask 2.

[0093]

[0094] ​​It should be noted that when a carbon nanotube network 121 with pores 121H is used in the protective film 12, the same transmittance can be achieved even if the protective film 12 becomes thicker. When a carbon nanotube network 121 with pores 121H is used in the protective film 12, the thickness of the protective film 12 is preferably 1000 nm or less.

[0095] The above describes the structure formed by stacking multiple carbon nanotube networks, but the protective film 12 can also adopt other structures.

[0096] Figure 1 To illustrate schematically, it can be used Figure 8 Plan view of other examples of protective films for protective film components. Figure 7 To illustrate schematically, it can be used Figure 7 A diagram of an example of a protective film made of carbon nanotubes.

[0097] Figure 8 The protective film 12 shown comprises: a plurality of first carbon nanotubes 122a extending along a first direction D1, and a plurality of second carbon nanotubes 122b extending along a second direction D2 intersecting the first direction D1. The first carbon nanotubes 122a and the second carbon nanotubes 122b form a fabric. The fabric can be plain weave, twill weave, or satin weave.

[0098] Each of the first carbon nanotube 122a and the second carbon nanotube 122b, for example, has the same characteristics as... Figure 8 The carbon nanotubes shown have the same structure as the carbon nanotubes 122. Figure 7 The carbon nanotube line 122 shown includes a plurality of carbon nanotubes 1200 extending along the length direction of the carbon nanotube line 122.

[0099] The thickness of the protective film 12 is preferably 500 nm or less. When the protective film 12 becomes thicker, the transmittance to the exposure light source (in this case, EUV light) decreases. The thickness of the protective film 12 is preferably 10 nm or more. When the protective film 12 becomes thinner, its mechanical strength decreases and the possibility of dust and other particles passing through the protective film 12 increases.

[0100] The thickness of each of the first carbon nanotube 122a and the second carbon nanotube 122b is preferably less than 100 nm. As their thickness increases, the protective film 12 becomes thicker. The thickness of each of the first carbon nanotube 122a and the second carbon nanotube 122b is preferably greater than 1 nm. As their thickness decreases, their mechanical strength decreases, and the productivity of the fabric decreases.

[0101] The protective film 12 preferably prevents dust particles with a diameter exceeding 30 nm from passing through. That is, the maximum distance between adjacent first carbon nanotubes 122a and adjacent second carbon nanotubes 122b is preferably less than 100 nm. It should be noted that even when the maximum distance between adjacent first carbon nanotubes 122a and adjacent second carbon nanotubes 122b is 100 nm, dust particles with a diameter exceeding 30 nm may still pass through, but this is mitigated by using multiple layers of the protective film with reference to a reference layer. Figure 9 The protective film 12 described has carbon nanotube layers of the same structure superimposed and used as a protective film, which can prevent dust from passing through.

[0102] The protective film 12 is manufactured, for example, by the following method.

[0103] Figure 3 A perspective view illustrating an example of a method for fabricating carbon nanotubes. First, by referring to... Figure 9 The method described is the same as the method preparation. Figure 9 The carbon nanotube array 120 shown.

[0104] Next, as Figure 8 As shown, carbon nanotubes 1200 are pulled out in a linear fashion from the end face of the carbon nanotube array 120. Van der Waals forces act on radially adjacent carbon nanotubes 1200. Therefore, for example, when the end face or a portion thereof of the carbon nanotube array 120 is held and stretched away from the carbon nanotube array 120, the carbon nanotubes 1200 are pulled out one after another from the carbon nanotube array 120. Thus, carbon nanotube lines 122 can be obtained without the use of adhesives or the like.

[0105] It should be noted that the carbon nanotubes 122 can be twisted together, or... Figure 10 They are not twisted together as shown. In the absence of twisting, most of the carbon nanotubes 1200 in the carbon nanotube wire 122 have a shape that extends along the direction in which they are pulled out.

[0106] Then, a fabric is formed using carbon nanotubes 122. The fabric is then pressed. This pressing can be performed on the entire fabric or on only one or more sections. Alternatively, pressing can be omitted.

[0107] A carbon nanotube membrane was obtained as described above. The carbon nanotube membrane thus obtained can be used as the aforementioned protective membrane 12.

[0108] In the carbon nanotube network 121, the first carbon nanotube line 122a and the second carbon nanotube line 122b are formed of the carbon nanotubes 1200, and a fabric is formed of them. The thickness of each of the first carbon nanotube line 122a and the second carbon nanotube line 122b can be controlled with high precision, and the arrangement of the first carbon nanotube line 122a and the second carbon nanotube line 122b can also be controlled with high precision. Thus, the carbon nanotubes 1200 and their intersections can be uniformly distributed. Therefore, the in-plane uniformity of the transmittance of the protective film 12 is also excellent.

[0109] The protective film 12 can be variously deformed.

[0110] Figure 8 A diagram of a carbon nanotube line involved in one deformation example is shown for illustrative purposes.

[0111] Referring to Figure 10 The diameter of the carbon nanotube line 122 described above is almost constant along the length direction thereof. In contrast to this, Figure 10 The diameter of the carbon nanotube line 122 shown in the drawing varies along the length direction thereof. Except for this aspect, Figure 8 The carbon nanotube line 122 shown in the drawing is the same as the carbon nanotube line 122 described with reference to Figure 5 Except for this, the carbon nanotube line 122 can be manufactured by the same method as described with reference to Figure 9 Except for this, the carbon nanotube line 122 can be manufactured by the same method as described with reference to Figure 2

[0112] By appropriately setting the arrangement, size of the holes or recesses 120H, and the speed at which the carbon nanotube network 121 is pulled out, and the like, the maximum diameter, the minimum diameter, and the pitch of the carbon nanotube line 122, and the like can be controlled. Furthermore, the positions of the large-diameter portion and the small-diameter portion of the carbon nanotube line 122 in the fabric can also be controlled with high precision. Thus, when this carbon nanotube line 122 is used in the protective film 12, for example, the transmittance of the protective film 12 and the in-plane uniformity thereof can be adjusted.

[0113] The protective film 12 can further include carbon nanotubes, carbon nanotube lines, carbon nanotube networks, a fabric made of carbon nanotube lines, or a coating layer that coats two or more of them. When the coating layer is provided, it can be made more difficult for dust and the like to pass through.

[0114] For example, with reference to Figure 6 ​The protective film 12 described can further include one or more coating layers that coat at least one of the first carbon nanotube network 121a and the second carbon nanotube network 121b. In this case, for example, the coating layer is provided on at least one of the networks before the first carbon nanotube network 121a and the second carbon nanotube network 121b are overlapped. The coating layer can also be provided on at least one of the networks after the first carbon nanotube network 121a and the second carbon nanotube network 121b are overlapped. In particular, as described with reference to Figure 4 As described, in the case where the carbon nanotube network 121 provided with the holes 121H is used in the protective film 12, by providing the coating layer, it is easy to achieve both high transmittance and difficulty of dust and the like from permeating.

[0115] Alternatively, as described with reference to ​ The protective film 12 described can further include one or more coating layers that coat at least one of the first carbon nanotube network 121a and the second carbon nanotube network 121b, and can further include one or more coating layers that coat the fabric formed by the first carbon nanotube line 122a and the second carbon nanotube line 122b. In the case of the former, for example, the coating layer is provided on at least one of the first carbon nanotube line 122a and the second carbon nanotube line 122b before the fabric is formed. In these cases, it is easy to achieve both high transmittance and difficulty of dust and the like from permeating.

[0116] The coating layer is composed of, for example, a metal or a semiconductor. According to one example, the coating layer includes one or more elements selected from the group consisting of silicon, molybdenum, ruthenium, boron, nitrogen, germanium, and hafnium. According to another example, the coating layer includes boron, boron carbide, zirconium nitride, molybdenum, ruthenium, silicon carbide, titanium nitride, amorphous carbon, graphene, or a combination of two or more of these.

[0117] Note that the carbon nanotube network, the carbon nanotube line, and the carbon nanotube film described herein can also be used for purposes other than the protective film assembly.

[0118] Explanation of symbols

[0119] 1…protective film assembly, 2…photomask, 11…frame, 12…protective film, 21…substrate, 22…multilayer reflective film, 22a…reflective layer, 22b…reflective layer, 23…cover film, 24…absorbing layer, 31…substrate, 32…catalyst layer, 120…carbon nanotube array, 120H…hole or recess, 121…carbon nanotube network, 121a…first carbon nanotube network, 121b…second carbon nanotube network, 121H…hole, 122…carbon nanotube line, 122a…first carbon nanotube line, 122b…second carbon nanotube line, 1200…carbon nanotube, 1200a…first carbon nanotube, 1200b…second carbon nanotube, D1…first direction, D2…second direction.

Claims

1. A protective film comprising: Multiple first carbon nanotubes extending along the first direction and arranged radially, and Multiple second carbon nanotubes extending radially along a second direction intersecting the first direction, respectively. The plurality of first carbon nanotubes form a first carbon nanotube network, and the plurality of second carbon nanotubes form a second carbon nanotube network that overlaps with the first carbon nanotube network. A plurality of pores (121H) are provided in at least one of the first carbon nanotube network and the second carbon nanotube network. The plurality of pores (121H) are formed by a plurality of pores or recesses (120H) disposed in the carbon nanotube array. The pores or recesses (120H) are blind pores, that is, recesses that are disposed on the surface of the carbon nanotube array and whose bottom surface is formed by the front ends of a plurality of carbon nanotubes. The carbon nanotube array having the holes or recesses (120H) is obtained as follows: a carbon nanotube array consisting of a plurality of carbon nanotubes extending from a support surface in a manner substantially perpendicular to the support surface is fabricated, and a mask layer with openings at positions corresponding to the holes or recesses (120H) is formed thereon, and then the carbon nanotubes are etched at the positions of these openings.

2. The protective film according to claim 1, further comprising one or more coating layers covering at least one of the carbon nanotube networks having the plurality of pores (121H).

3. The protective film according to claim 1, wherein, The maximum diameter of the plurality of holes (121H) is less than 100 nm.

4. The protective film according to claim 2, wherein, The maximum diameter of the plurality of holes (121H) is less than 100 nm.

5. The protective film according to any one of claims 1 to 4, wherein the thickness is less than 500 nm.

6. A protective film, comprising: Multiple first carbon nanotube lines, each made of multiple first carbon nanotubes and extending along a first direction, and Multiple second carbon nanotube lines, each made of a plurality of second carbon nanotubes and extending along a second direction that intersects the first direction, The plurality of first carbon nanotubes and the plurality of second carbon nanotubes form a fabric. The maximum distance between adjacent first carbon nanotubes and between adjacent second carbon nanotubes is less than 100 nm.

7. The protective film according to claim 6, wherein, One or more of the plurality of first carbon nanotubes and the plurality of second carbon nanotubes have a diameter that varies along the length direction.

8. The protective film according to claim 6 or 7, wherein the thickness is less than 500 nm.

9. A protective membrane assembly, comprising: The protective film according to any one of claims 1 to 8, and the frame supporting the protective film.

10. A carbon nanotube network comprising a plurality of carbon nanotubes extending in one direction and arranged radially, and having a plurality of pores (121H). The plurality of pores (121H) are formed by a plurality of pores or recesses (120H) disposed in the carbon nanotube array. The pores or recesses (120H) are blind pores, that is, recesses that are disposed on the surface of the carbon nanotube array and whose bottom surface is formed by the front ends of a plurality of carbon nanotubes. The carbon nanotube array having the holes or recesses (120H) is obtained as follows: a carbon nanotube array consisting of a plurality of carbon nanotubes extending from a support surface in a manner substantially perpendicular to the support surface is fabricated, and a mask layer with openings at positions corresponding to the holes or recesses (120H) is formed thereon, and then the carbon nanotubes are etched at the positions of these openings.

11. A carbon nanotube membrane, comprising: A network of first carbon nanotubes comprising multiple first carbon nanotubes extending along a first direction and arranged radially, and A second carbon nanotube network comprising a plurality of second carbon nanotubes extending along a second direction intersecting the first direction and arranged radially. At least one of the first carbon nanotube network and the second carbon nanotube network is provided with a plurality of pores (121H). The plurality of pores (121H) are formed by a plurality of pores or recesses (120H) disposed in the carbon nanotube array. The pores or recesses (120H) are blind pores, that is, recesses that are disposed on the surface of the carbon nanotube array and whose bottom surface is formed by the front ends of a plurality of carbon nanotubes. The carbon nanotube array having the holes or recesses (120H) is obtained as follows: a carbon nanotube array consisting of a plurality of carbon nanotubes extending from a support surface in a manner substantially perpendicular to the support surface is fabricated, and a mask layer with openings at positions corresponding to the holes or recesses (120H) is formed thereon, and then the carbon nanotubes are etched at the positions of these openings.

12. A method for manufacturing a carbon nanotube network, comprising: Prepare a carbon nanotube array consisting of multiple carbon nanotubes extending from the support surface and having more than one pore or depression (120H). as well as Carbon nanotubes are pulled out in a mesh-like pattern from the end faces of the carbon nanotube array. The hole or recess (120H) is a blind hole, that is, a recess that is disposed on the surface of the carbon nanotube array and whose bottom surface is composed of the front ends of multiple carbon nanotubes. The carbon nanotube array having the holes or recesses (120H) is obtained as follows: a carbon nanotube array consisting of a plurality of carbon nanotubes extending from the support surface in a manner substantially perpendicular to the surface is fabricated, and a mask layer is formed thereon with openings at positions corresponding to the holes or recesses (120H), and then the carbon nanotubes are etched at the positions of these openings.

13. A method for manufacturing carbon nanotubes, comprising: Prepare a carbon nanotube array consisting of multiple carbon nanotubes extending from the support surface and having more than one pore or depression (120H). as well as Carbon nanotubes are pulled out in a linear fashion from the end face of the carbon nanotube array. The hole or recess (120H) is a blind hole, that is, a recess that is disposed on the surface of the carbon nanotube array and whose bottom surface is composed of the front ends of multiple carbon nanotubes. The carbon nanotube array having the holes or recesses (120H) is obtained as follows: a carbon nanotube array consisting of a plurality of carbon nanotubes extending from the support surface in a manner substantially perpendicular to the surface is fabricated, and a mask layer is formed thereon with openings at positions corresponding to the holes or recesses (120H), and then the carbon nanotubes are etched at the positions of these openings.

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