Carbon-containing diffusion barrier layer for protecting CNT EUV pellicle

Abstract

The invention relates to a carbon-containing diffusion barrier layer for protecting a CNT EUV pellicle. In particular, the present application provides a pellicle including a pellicle diaphragm having improved stability to hydrogen plasma. The pellicle sheet includes a plurality of carbon nanotubes (CNTs), wherein at least one of the plurality of carbon nanotubes (CNTs) is coated with a protective coating. The protective coating includes a plurality of nanostructures on a surface of at least one CNT of the plurality of CNTs and including a transition metal or an oxide, nitride, silicide or carbide thereof, a carbon-based diffusion barrier layer over at least the plurality of nanostructures, and a capping layer over at least the carbon-based diffusion barrier layer. The pellicle further includes a pellicle boundary attached to the pellicle membrane along a peripheral region of the pellicle membrane and a pellicle frame attached to the pellicle boundary.

Description

[0001] Priority claims and cross references

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 615,191, filed on December 27, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to a carbon-containing diffusion barrier layer for protecting a CNT EUV protective film. Background Art

[0004] In the semiconductor integrated circuit (IC) industry, technological advances in IC materials and design have resulted in successive generations of ICs, each smaller and more complex than the previous generation. In the evolution of ICs, functional density (i.e., the number of interconnected devices per unit chip area) has generally increased, while geometric size (i.e., the smallest component or line that can be manufactured using a manufacturing process) has decreased. This scaling down process generally brings benefits by improving production efficiency and reducing associated costs. However, this scaling down process also increases the complexity of IC processing and manufacturing.

[0005] In the process of manufacturing IC devices, a circuit pattern is formed on a wafer using a photolithography process. In the photolithography process, a desired pattern is transferred to the wafer using a photomask. When the photomask is contaminated by foreign matter (such as particles) in the surrounding environment, defects may appear on the wafer to which the pattern of the photomask is transferred. Summary of the invention

[0006] Some embodiments of the present application provide a protective film, which includes: a protective film sheet including a plurality of carbon nanotubes (CNTs), wherein at least one of the plurality of CNTs is coated with a protective coating, the protective coating including: a plurality of first nanostructures on the surface of at least one CNT among the plurality of CNTs, the plurality of first nanostructures including a transition metal or its oxide, nitride, silicide or carbide; a carbon-based diffusion barrier layer on at least the plurality of first nanostructures; and a capping layer on at least the carbon-based diffusion barrier layer; and a protective film boundary, the protective film boundary being attached to the protective film sheet along a peripheral area of ​​the protective film sheet; and a protective film frame, the protective film frame being attached to the protective film boundary.

[0007] Some embodiments of the present application provide a pellicle-photomask structure, which includes: an extreme ultraviolet (EUV) photomask including a pattern area; and a pellicle attached to a peripheral area of ​​the EUV photomask, the pellicle including a pellicle film sheet extending across the pattern area of ​​the EUV photomask, the pellicle film sheet including a plurality of carbon nanotubes (CNTs), wherein the plurality of CNTs are covered by a protective coating, the protective coating including: a plurality of first nanostructures on a surface of at least one CNT among the plurality of CNTs; a carbon-based diffusion barrier layer above the plurality of first nanostructures; and a capping layer above the carbon-based diffusion barrier layer.

[0008] Some embodiments of the present application provide a method for forming a protective film for an extreme ultraviolet (EUV) photomask, the method comprising the following steps: forming a plurality of functional groups on the surface of a plurality of carbon nanotubes (CNTs); growing a plurality of nanostructures on the surface of the plurality of CNTs using the plurality of functional groups as nucleation sites; forming a carbon-based diffusion barrier layer to encapsulate the plurality of nanostructures; and forming a conformal capping layer covering the carbon-based diffusion barrier layer and the plurality of CNTs. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The various aspects of the present application can be better understood by reading the following detailed description in conjunction with the accompanying drawings. It should be noted that, in accordance with industry standard practice, various features are not drawn to scale. In fact, for ease of discussion, the size of various features can be arbitrarily increased or reduced.

[0010] Figure 1 is a schematic diagram of a lithography system according to some embodiments.

[0011] Figure 2A is a cross-sectional view of a pellicle-photomask structure according to some embodiments.

[0012] Figure 2B According to some embodiments Figure 2A An isometric view of the pellicle-photomask structure is shown.

[0013] Figure 2C According to some embodiments Figure 2A and Figure 2B A top view of a pellicle membrane is shown.

[0014] Figure 2D According to some embodiments Figure 2C A cross-sectional view of a coated carbon nanotube in a network of carbon nanotubes is shown.

[0015] Figures 3A-3D According to some embodiments Figure 2D Cross-sectional views of various examples of protective coatings are shown.

[0016] Figure 4 is a flow chart illustrating a method of assembling a pellicle for a photolithography process according to some embodiments.

[0017] Figures 5A-5E are cross-sectional views of a cover film at various stages of the method according to claim 4, according to some embodiments.

[0018] Figure 6 is a flow chart illustrating a method of forming a protective coating on carbon nanotubes according to some embodiments.

[0019] Figures 7A-7D ' is a protective coating according to some embodiments Figure 6 Cross-sectional views of various stages of the method shown.

[0020] Figure 8 is a flow chart illustrating a method of forming a protective coating on carbon nanotubes according to some embodiments.

[0021] Figures 9A-9E ' is a protective coating according to some embodiments Figure 8 Cross-sectional views of various stages of the method shown.

[0022] Fig.10 is a flow chart illustrating a method of manufacturing a semiconductor device according to some embodiments.

[0023] Figures 11A-11D According to some embodiments, a semiconductor device Fig.10 Cross-sectional views of various stages of the method shown. DETAILED DESCRIPTION

[0024] The following disclosure provides many different embodiments or examples for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present application. Of course, these are merely examples and are not restrictive. For example, in the following description, the formation of a first feature on or on a second feature may include an embodiment in which the first feature and the second feature are directly contacted and formed, and may also include an embodiment in which additional features may be formed between the first feature and the second feature so that the first feature and the second feature may not be in direct contact. In addition, the present application may also repeatedly quote numbers and / or letters in various examples. This repetition is for simplicity and clarity, and does not itself determine the relationship between the various embodiments and / or configurations discussed.

[0025] Additionally, for ease of description, spatially relative terms (such as, "below," "beneath," "lower," "above," "upper," etc.) may be used herein to describe the relationship of one element or feature to another element or feature as shown in the figures. Spatially relative terms also include different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may also be in other orientations (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein may be interpreted accordingly.

[0026] The photomask used in the photolithography patterning process includes the desired mask pattern. The photomask can be a reflective mask or a transmissive mask. In this process, ultraviolet rays are reflected from the surface of the photomask (reflective mask) or transmitted through the photomask (transmissive mask) to transfer the pattern to the photoresist on the semiconductor wafer. The exposed portion of the photoresist is photochemically modified. After exposure, the photoresist is developed to define an opening on the photoresist, and then one or more semiconductor processing steps (e.g., etching, epitaxial layer deposition, metallization, etc.) are performed, which operate on those areas of the wafer surface exposed by the opening on the photoresist. After completing the semiconductor processing, the photoresist is removed with a suitable resist stripper or the like.

[0027] The minimum feature size of the pattern is limited by the wavelength of light. Deep ultraviolet (UV) lithography, for example, uses a wavelength of 193nm or 248nm in some standard deep UV platforms, typically uses a transmissive mask and provides a smaller minimum feature size than lithography at longer wavelengths. Extreme ultraviolet (EUV) light, with wavelengths ranging from 124nm to 10nm, is currently being used to provide an even smaller minimum feature size. At shorter wavelengths, particulate contamination on the photomask can cause defects in the transferred pattern. Therefore, a pellicle is used to protect the photomask from such particulate contamination. The pellicle includes a pellicle membrane sheet attached to a mounting frame. The mounting frame supports the pellicle membrane sheet above the photomask. Any contaminating particles that fall on the pellicle membrane sheet are blocked outside the focal plane of the photomask. Therefore, defects in the transferred pattern are reduced or avoided.

[0028] Since the pellicle covers the photomask during the exposure process, strict requirements are imposed on its absorption capacity, durability, and particle shielding ability. The pellicle used for EUV reflective masks needs to meet several key requirements: (1) long service life in the hydrogen-rich radical working environment of the EUV stepper / scanner; (2) high mechanical strength to minimize sagging effects during vacuum pumping and venting operations; (3) high or perfect blocking performance for particles larger than about 20nm (called "killer particles"); and (4) good heat dissipation performance to prevent the pellicle from being damaged by EUV radiation. In the field of EUV lithography, finding a suitable pellicle material with high transmittance and stability at EUV wavelengths has always been a challenge.

[0029] Carbon nanotubes (CNTs) have emerged as a suitable material for pellicles in EUV reflective photomasks. CNTs offer high EUV transmittance and mechanical stability, as well as low EUV scattering and reflectivity. However, during EUV lithography, pellicles may be exposed to hydrogen plasma, which poses a challenge because CNTs in their pristine state are easily damaged by hydrogen plasma due to crystalline defects on the surface of the CNTs. This damage can shorten the life of the pellicle.

[0030] Embodiments of the present application provide a pellicle membrane comprising a plurality of CNTs, characterized by high transparency and durability. The CNTs in the pellicle membrane are covered by a protective coating to prevent them from being affected by hydrogen radicals / ions when exposed in an EUV scanner, thereby extending the service life of the membrane. In these embodiments, the protective coating includes a single type or two different types of transition metal-containing nanostructures formed on the surface of the CNTs for hydrogen reduction. These transition metal-containing nanostructures are encapsulated by a carbon-based diffusion barrier layer to prevent heat accumulation during EUV exposure. Finally, a conformal capping layer is applied as the outermost layer, covering the carbon-based diffusion barrier layer and, in some cases, also covering the CNTs themselves to inhibit hydrogen penetration.

[0031] Figure 1 1 is a schematic diagram of a lithography system 100 according to some embodiments. The lithography system 100 may also be generally referred to as a "scanner", which can be used to perform a lithography process, including using a corresponding radiation source and exposing in a specific exposure mode.

[0032] In some embodiments, the lithography system 100 includes a high brightness light source 102, an illuminator 104, a mask stage 106, a photomask 108, a projection optics module 110, and a substrate stage 112. In some embodiments, the lithography system 100 may include Figure 1In some embodiments, one or more of the high brightness light source 102, the illuminator 104, the mask stage 106, the photomask 108, the projection optics module 110, and the substrate stage 112 may be omitted from the lithography system 100 or may be integrated into modular components.

[0033] The high brightness light source 102 can be configured to emit radiation having a wavelength in the range of about 1 nanometer (nm) to 250 nm. In some embodiments, the high brightness light source 102 generates EUV light centered at a wavelength of about 13.5 nm; therefore, in some embodiments, the high brightness light source 102 may also be referred to as an "EUV light source". However, it will be appreciated that the high brightness light source 102 should not be limited to emitting EUV light. For example, the high brightness light source 102 may be used to perform any high intensity photon emission from an excited target. In some embodiments, the high brightness light source 102 may be an i-line, G-line, 248 nm, 193 nm, deep ultraviolet (DUV), sub-EUV, soft X-ray, or X-ray light source.

[0034] In embodiments where the lithography system 100 is a UV lithography system, the illuminator 104 may include various refractive optical components, such as a single lens or a lens system including multiple lenses (zone plates). In some embodiments, the illumination may include mirrors, concave mirrors, convex mirrors, lenses, pellicle mirrors, beam splitters, semi-transparent mirrors, waveguides, dynamic gas lock (DGL) diaphragms. In embodiments where the lithography system 100 is an EUV lithography system, the illuminator 104 may include various reflective optical components, such as a single mirror or a mirror system including multiple mirrors. The illuminator 104 may direct light from the high brightness light source 102 onto the mask stage 106, and in particular onto the photomask 108 fixed to the mask stage 106. In embodiments where the light generated by the high brightness light source 102 is in the EUV wavelength range, the illuminator 104 includes a reflective optical device.

[0035] The mask stage 106 can be configured to hold the photomask 108. In some embodiments, the mask stage 106 can include an electrostatic chuck (e-chuck) for holding the photomask 108. This is because gas molecules absorb EUV light, and the lithography system 100 for EUV lithography patterning is maintained in a vacuum environment to minimize EUV intensity loss. In this document, the terms "photomask", "mask" and "reticle" can be used interchangeably. In one example, the photomask 108 is a reflective mask.

[0036] In some embodiments, a pellicle 114 can be positioned over the photomask 108, for example, between the photomask 108 and the substrate stage 112. The pellicle 114 can protect the photomask 108 from particles and can keep the particles out of focus so that the particles do not create an image that could cause defects on the wafer during the photolithography process.

[0037] The projection optics module 110 can be configured to image the pattern of the photomask 108 onto a semiconductor wafer 116 secured to a substrate stage 112. In some embodiments, the projection optics module 110 includes refractive optics (such as for a UV lithography system). In some embodiments, the projection optics module 110 includes reflective optics (such as for an EUV lithography system). Light directed from the photomask 108 carrying an image of the pattern defined on the photomask 108 can be collected by the projection optics module 110. The illuminator 104 and the projection optics module 110 can be collectively referred to as an "optical module" of the lithography system 100.

[0038] In some embodiments, the semiconductor wafer 116 may be a bulk semiconductor wafer. For example, the semiconductor wafer 116 may include a silicon wafer. The semiconductor wafer 116 may include silicon or another semiconductor elemental material, such as germanium. In some embodiments, the semiconductor wafer 116 may include a compound semiconductor. The compound semiconductor may include gallium arsenide, silicon carbide, indium arsenide, indium phosphide, another suitable material, or a combination thereof.

[0039] In some embodiments, semiconductor wafer 116 includes a silicon-on-insulator (SOI) substrate. The SOI substrate can be manufactured using a separation by implantation of oxygen (SIMOX) process, a wafer bonding process, another suitable process, or a combination thereof.

[0040] In some embodiments, the semiconductor wafer 116 includes an undoped substrate. However, in other embodiments, the semiconductor wafer 116 includes a doped substrate, such as a p-type substrate or an n-type substrate.

[0041] In some embodiments, the semiconductor wafer 116 includes various doped regions (not shown) according to the design requirements of the semiconductor device structure. The doped regions may include, for example, a p-type well and / or an n-type well. In some embodiments, the doped regions are doped with a p-type dopant. For example, the doped regions may be doped with boron or boron fluoride. In other embodiments, the doped regions are doped with an n-type dopant. For example, the doped regions may be doped with phosphor or arsenic. In some embodiments, some doped regions are p-doped and other doped regions are n-doped.

[0042] In some embodiments, an interconnect structure may be formed on the semiconductor wafer 116. The interconnect structure may include multiple interlayer dielectric layers, including dielectric layers. The interconnect structure may also include multiple conductive features formed in the interlayer dielectric layers. The conductive features may include conductive lines, conductive through-holes, and / or conductive contacts.

[0043] In some embodiments, various device elements are formed in the semiconductor wafer 116. Examples of various device elements may include transistors (e.g., metal oxide semiconductor field effect transistors (MOSFETs), complementary metal oxide semiconductor (CMOS) transistors, bipolar junction transistors (BJTs), high voltage transistors, high frequency transistors, p-channel and / or n-channel field effect transistors (PFETs and / or NFETs), diodes, or other suitable elements. Various processes may be used to form the various device elements, including deposition, etching, implantation, photolithography, annealing, and / or other suitable processes.

[0044] The device elements may be interconnected via an interconnect structure on the semiconductor wafer 116 to form an integrated circuit device. The integrated circuit device may include a logic device, a memory device (e.g., a static random access memory (SRAM) device), a radio frequency (RF) device, an input / output (I / O) device, a system on a chip (SoC) device, an image sensor device, other applicable devices, or a combination thereof.

[0045] In some embodiments, a photoresist layer sensitive to EUV light may be coated on the semiconductor wafer 116. Various components including the above components may be integrated together and may be used to perform a photolithography exposure process.

[0046] Figure 2A is a cross-sectional view of a pellicle-photomask structure 200 according to some embodiments of the present application. Figure 2B yes Figure 2A An isometric view of the pellicle-photomask structure 200 is shown. Figure 2A and Figure 2B As shown, the photomask 108 may include a mask substrate 202 and a mask pattern 204 positioned over the mask substrate 202 .

[0047] In some embodiments, the mask substrate 202 includes a transparent substrate such as relatively defect-free fused quartz, borosilicate glass, soda-lime glass, calcium fluoride, a low thermal expansion material, an ultra-low thermal expansion material, or other suitable materials. As described above, the mask pattern 204 can be positioned on the mask substrate 202 and can be positioned according to the semiconductor wafer (e.g., Figure 1The mask pattern 204 may be designed to be a feature of an integrated circuit formed on a semiconductor wafer 116 in the semiconductor wafer 116. The mask pattern 204 may be formed by depositing a material layer and patterning the material layer to have one or more openings through which a radiation beam can pass but is not absorbed and one or more absorption regions that can completely or partially block the radiation beam.

[0048] The mask pattern 204 may include metal, metal alloy, metal silicide, metal nitride, metal oxide, metal oxynitride or other suitable materials. Examples of materials that can be used to form the mask pattern 204 may include, but are not limited to: Cr, Mo x Si y 、 x Si y 、Mo、Nb x O y 、Ti、Ta、Cr x N y 、Mo x O y 、Mo x N y Cr x O y 、Ti x N y 、Zr x N y 、Ti x O y 、 x N y 、 x O y 、Si x O y , Nb x N y 、Zr x N y 、Al x O y N z 、 x B y O z 、 x B y N z 、Ag x O y 、Ag x N y ,Ni,Ni x O y 、Ni x O y N z And / or similar materials. The ratio of compound x / y / z is not limited.

[0049] In some embodiments, the photomask 108 is an EUV mask. However, in some other embodiments, the photomask 108 may be an optical mask.

[0050] like Figure 2A and Figure 2B As shown, the pellicle 114 can be positioned on the photomask 108. The pellicle 114 and the photomask 108 can form a closed inner cavity 227 surrounded by the pellicle 114 and the photomask 108. The pellicle 114 and the photomask 108 isolate the inner cavity 227 from the external environment 228. In some embodiments, the pellicle 114 includes a pellicle frame 206, which can be positioned on at least one of the mask substrate 202 and the mask pattern 204. In some embodiments, the pellicle frame 206 can be formed of Si, SiC, SiN, glass, a low thermal expansion coefficient material (such as, Al alloy, Ti alloy, Invar, Kovar or similar material), another suitable material, or a combination thereof. In some embodiments, a suitable process for forming the pellicle frame 206 can include a machining process, a sintering process, a photochemical etching process, other applicable processes, or a combination thereof.

[0051] In some embodiments, the pellicle frame 206 may include a side portion 208 having an inner surface 210 and an outer surface 212, wherein the inner surface 210 and the outer surface 212 are oriented on opposite sides of the side portion 208. The pellicle frame 206 may also include a bottom surface 214 or a bottom connecting the inner surface 210 and the outer surface 212.

[0052] like Figure 2A and Figure 2B As further shown in FIG. 2 , the pellicle-photomask structure 200 may also include a vent structure 216 formed in the side 208 and extending from the inner surface 210 to the outer surface 212. In some embodiments, the vent structure 216 may include one or more apertures formed in the side 208 of the pellicle frame 206. The apertures may be in any shape, including circular apertures, rectangular apertures, slit-shaped apertures, other shapes, or any combination thereof. The apertures may allow airflow through a portion of the pellicle-photomask structure 200. In some embodiments, the vent structure 216 of the pellicle frame 206 may be formed such that at least one side 208 of the pellicle frame 206 includes one aperture formed at the top of the side 208 (e.g., near the boundary 224) and another aperture formed at the bottom of the side 208 (e.g., near the mask pattern 204). In some embodiments, the apertures may include filters to minimize the passage of foreign particles through the vent structure 216.

[0053] In some embodiments, when the vent structure includes a filter, the vent structure 216 can be formed together with the pellicle frame 206. In some embodiments, the vent structure 216 can be formed using a photochemical etching process, another suitable process, or a combination thereof.

[0054] In some other embodiments, when the vent structure includes a filter, the vent structure 216 and the pellicle frame 206 can be formed separately, and an opening (not shown) can be formed in the side 208 of the pellicle frame 206. Thereafter, in some embodiments, the vent structure 216 can be placed into the opening in the side 208 of the pellicle frame 206. The vent structure 216 can then be bonded to the pellicle frame 206, for example, by a brazing process, a direct diffusion bonding process, a eutectic bonding process, another suitable process, or a combination thereof. In some embodiments, the vent structure 216 can prevent the pellicle membrane 226 from breaking during the EUV lithography process.

[0055] like Figure 2A and Figure 2B As further shown in FIG. 2 , the pellicle-photomask structure 200 may further include a pellicle frame adhesive 218 positioned between the pellicle frame 206 and the mask substrate 202 .

[0056] In some embodiments, the film frame adhesive 218 can be made of a thermoplastic elastomer or other polymer adhesive material that is curable when heated or under UV light. In various examples, the adhesive includes polybutylene resin, polyvinyl acetate resin, acrylic resin, silicone resin, epoxy resin, etc.

[0057] In some embodiments, the pellicle frame 206 may be surface treated to enhance adhesion of the pellicle frame 206 to the pellicle frame adhesive 218. In some embodiments, the surface treatment may include an oxygen plasma treatment, another suitable treatment, or a combination thereof. However, in other embodiments, the pellicle frame 206 may not be surface treated.

[0058] The pellicle-photomask structure 200 may further include a pellicle sheet adhesive 220 positioned above the pellicle frame 206. In some embodiments, the pellicle sheet adhesive 220 may be formed of a thermoplastic elastomer type adhesive, a polystyrene type adhesive, an acrylic type adhesive, a silicone-based adhesive, an epoxy type adhesive, another suitable adhesive, or a combination thereof. In some embodiments, the material forming the pellicle sheet adhesive 220 may be different from the material constituting the pellicle frame adhesive 218.

[0059] like Figure 2A and Figure 2BAs further shown in FIG. 2 , the pellicle-photomask structure 200 may also include a pellicle sheet assembly 222 positioned over the pellicle frame 206 and the pellicle sheet adhesive 220 . As shown, the pellicle sheet adhesive 220 may be positioned between the pellicle sheet assembly 222 and the pellicle frame 206 .

[0060] In some embodiments, pellicle assembly 222 can include a border 224 positioned on pellicle adhesive 220 and a pellicle 226 positioned on border 224. In some embodiments, border 224 can be formed of Si. In further embodiments, border 224 can be formed of boron carbide, graphene, carbon nanotubes, SiC, SiN, SiO2, SiON, Zr, Nb, Mo, Cd, Ru, Ti, Al, Mg, V, Hf, Ge, Mn, Cr, W, Ta, Ir, Zn, Cu, F, Co, Au, Pt, Sn, Ni, Te, Ag, another suitable material, an allotrope of any of these materials, or a combination thereof. Border 224 can mechanically support pellicle 226 around its periphery. When pellicle-photomask structure 200 is fully assembled, border 224 can then be mechanically supported by pellicle frame 206. That is, the pellicle frame 206 may mechanically support the boundary 224 and the pellicle 226 of the pellicle assembly 222 on the photomask 108 .

[0061] The pellicle 226 has a complex refractive index with an n value in the range of about 0.8 to about 1 and a k value in the range of about 0.01 to 0.1. In some embodiments, the pellicle 226 can be formed by a network 229 of multiple CNTs. The CNTs can be single-walled CNTs (SWCNTs), double-walled CNTs (DWCNTs), multi-walled CNTs (MWCNTs), or a combination thereof. The wall thickness of the CNTs can vary from about 0.01 nm to about 100 nm. The CNTs in the pellicle 226 can be individual, unbundled CNTs, or bundled individual CNTs. Bundled individual CNTs form CNT bundles. The term "CNT bundle" refers to more than 10 individual CNTs entangled with each other. Although there is no theoretical limitation, in certain embodiments, a CNT bundle can consist of up to 20 CNTs. For example, Figure 2C Shows Figure 2A and Figure 2B An example of a protective membrane 226 is shown. Figure 2CIn the example shown, the overcoat membrane sheet 226 includes a CNT membrane layer formed of a network 229 of randomly oriented CNTs. In some embodiments, the overcoat membrane sheet 226 has a multilayer structure including multiple CNT membrane layers. In some embodiments, each of the multiple CNT membrane layers is formed of a network 229 of randomly oriented CNTs. In other embodiments, the multiple CNT membrane layers are formed of directionally oriented CNTs, wherein the CNTs in adjacent layers are arranged at a certain angle to each other.

[0062] In some embodiments, the network 229 of CNTs that make up the pellicle membrane 226 can have a structural density between 0.2 and 1, depending on the desired percentage of radiation to be transmitted through the pellicle membrane 226. For example, the pellicle membrane 226 has been shown to have a light transmittance of up to about 90%. The precise structural density can be selected to maximize EUV radiation transmittance while maximizing the passage of particles through the pellicle membrane 226. For example, while a looser structural density can achieve higher EUV radiation transmittance, a looser structural density may also cause particles to fall onto the photomask 108.

[0063] In some embodiments, the thickness of the pellicle membrane 226 may vary from about 5 nm to about 100 nm. In more specific embodiments, the thickness of the pellicle membrane 226 is about 20 nm to about 50 nm. These ranges have been found to provide sufficient robustness for the pellicle membrane 226 while also providing high EUV transmittance. Generally speaking, the thicker the pellicle membrane 226, the stronger the pellicle membrane 226; however, if the pellicle membrane 226 is too thick, the EUV transmittance may be reduced. Therefore, the disclosed range strikes a balance between these two goals. In some embodiments, the transmittance of the pellicle membrane is not less than 50%.

[0064] CNTs are susceptible to degradation due to exposure to hydrogen plasma (such as the type employed during operation or maintenance of a lithography system). In order to extend the useful life of the CNT pellicle in the scanning environment of an EUV-induced hydrogen-based plasma, in an embodiment of the present application, one or more CNTs in a network of multiple CNTs are coated with a protective coating. For example, in some embodiments, more than 90% of the individual CNTs in a network of multiple CNTs are coated with a protective coating. In some embodiments, more than 95%, more than 98%, or 100% of the individual CNTs in a network 229 of multiple CNTs are coated with a protective coating. For example, Figure 2D Shows Figure 2C A cross-sectional view of a coated CNT 300 in a network 229 of multiple CNTs is shown. Figure 2DAs shown, a protective coating 240 is coated on a CNT 230 in a raw state to provide a coated CNT 300. In some embodiments, the coated CNT 300 has a core-shell structure including a CNT core and a protective coating shell. In an embodiment of the present application, the protective coating 240 is characterized by a multilayer structure, including a metal-containing seed layer, a carbon-based diffusion barrier layer, and a capping layer, for protecting the CNT 230 in a raw state from damage by hydrogen plasma, as described below.

[0065] In some embodiments, the total thickness of the protective coating 240 is in the range of about 1 nm to about 40 nm. When the thickness of the protective coating 240 is greater than this range, the EUV transmittance of the pellicle membrane 226 may be reduced, and when the thickness of the protective coating is less than this range, the mechanical strength of the pellicle membrane 226 may be insufficient.

[0066] Figures 3A-3D is a cross-sectional view showing various examples of coated CNTs 300 in a network of a plurality of CNTs according to an embodiment of the present application. Figures 3A-3D The coated CNTs 300 depicted in FIG. 2 differ from one another based on the composition and / or configuration of the protective coating 240 surrounding the CNTs 230 .

[0067] Figure 3A is a cross-sectional view of a first example of a coated CNT 300 in a network of a plurality of CNTs 230 according to some embodiments. Figure 3A As shown, the protective coating 240 surrounding the CNT 230 includes a seed layer 250 , a diffusion barrier layer 260 on the seed layer 250 , and a capping layer 270 on the diffusion barrier layer 260 .

[0068] The seed layer 250 is formed on the surface of the CNT 230, but does not completely cover the CNT 230. The seed layer 250 is suitable for reducing the number of hydrogen radicals reaching the surface of the CNT 230. In some embodiments, the seed layer 250 includes a plurality of nanostructures 252, the size of which is in the nanometer range. The use of discrete nanostructures 252 instead of a continuous conformal layer is to minimize the effect of the presence of these nanostructures 252 on EUV transmittance, because these nanostructures 252 absorb EUV radiation. In addition, the geometry of the nanostructures 252 provides a larger surface area compared to a continuous conformal layer, resulting in improved reduction of hydrogen or oxygen by increasing the reaction area. In some embodiments, the nanostructures 252 can have different morphologies, so that the cross-sectional profiles of the nanostructures 252 are different from each other. In some embodiments, the size of the nanostructures 252 can be in the range of about 0.5nm to about 5nm. The nanostructures 252 can take any shape. For example, in some embodiments, the nanostructures 252 may be nano-grains, nano-islands, nano-cubes, nano-sheets, or combinations thereof. Figure 3A As shown, the seed layer 250 includes a plurality of nanostructures 252 on the surface of the CNT 230. In some embodiments, the nanostructures 252 are uniformly distributed on the surface of the CNT 230. In some other embodiments, the nanostructures 252 are randomly distributed on the surface of the CNT 230. The size of the nanostructures 252 is selected to ensure that the nanostructures 252 do not block the transmission of EUV light.

[0069] In some embodiments, the nanostructure 252 is composed of a material that can effectively react with hydrogen radicals generated during EUV exposure in an EUV scanner, thereby reducing damage to the CNT 230 caused by these hydrogen radicals. In some embodiments, the material in the nanostructure 252 can also serve as a catalyst for growing a two-dimensional (2-dimendional) carbon material (such as graphene) to be used as a diffusion barrier layer 260. In some embodiments, the nanostructure 252 is composed of a transition metal or a compound thereof. Examples of suitable transition metals include, but are not limited to, chromium (Cr), cobalt (Co), copper (Cu), iridium (Ir), iron (Fe), gold (Au), manganese (Mn), molybdenum (Mo), nickel (Ni), niobium (Nb), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), silver (Ag), tantalum (Ta), titanium (Ti), tungsten (W), vanadium (V) and zirconium (Zr). In some embodiments, such a compound of a transition metal may include an oxide, nitride, silicide or carbide of the transition metal. In some embodiments, the nanostructure 252 includes Co, Ir, Fe, Nb, Ni, Pt, Rh, Ru, Ti, RuO2, RuSi2, RuSi, Ru2Si3, Nb2O5, Mo, MoO2, or TiO2. In some embodiments, the nanostructure 252 includes Ru or RuO2.

[0070] In some embodiments, the nanostructure 252 can be formed by sol-gel, E-beam evaporation, chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), atomic layer deposition (ALD), plasma enhanced ALD, thermal ALD, electrodeposition, electroless deposition, or other suitable deposition techniques.

[0071] A diffusion barrier layer 260 is formed on the seed layer 250. The diffusion barrier layer 260 is suitable for preventing agglomeration of the nanostructure 252. Since the nanostructure 252 is small in size and has a high surface energy, when heat accumulates on the nanostructure 252, the nanostructure 252 is easily agglomerated and forms larger agglomerates. This agglomeration will cause the nanostructure 252 to migrate or diffuse. Therefore, the agglomeration of the nanostructure will reduce the EUV transmittance of the pellicle membrane 226. The diffusion barrier layer 260 encapsulates the nanostructure 252 and acts as a barrier to prevent the migration or diffusion of the nanostructure 252. Its formation helps to inhibit the agglomeration of the nanostructure 252. Therefore, the reliability of the pellicle membrane 226 is improved, while the high EUV transmittance of the pellicle membrane 226 is maintained. Figure 3AIn the first example shown, the diffusion barrier layer 260 is formed as a discontinuous layer, appearing only on the surface of the nanostructures 252, while the surface of the portion of the CNT 230 between the nanostructures 252 remains uncovered. The diffusion barrier layer 260 may include a carbon-based material, which has a lower EUV absorption rate and a higher EUV transmittance than other non-carbon-based materials. The carbon-based material also exhibits a 400Wm -1 K -1 The thermal conductivity of the carbon-based material is 400 Wm-1 or higher, which helps prevent the nanostructures 252 from migrating due to heat accumulation during the deposition process of forming the protective coating 240 or during EUV exposure of EUV lithography. -1 K -1 Up to 4050Wm -1 K -1 In some embodiments, the diffusion barrier layer 260 may include graphene, amorphous carbon, graphite, or diamond-like carbon. In some embodiments, the diffusion barrier layer 260 includes a thermal conductivity of about 4000±50 Wm -1 K -1 The graphene has a thermal conductivity greater than that of the material constituting the bottom nanostructure 252 (e.g., Ru (120 ± 50 Wm -1 K -1 ) or RuO2(50±50Wm -1 K -1 Therefore, the graphene-based diffusion barrier layer 260 can quickly dissipate the heat load and prevent the Ru-containing nanostructure from accumulating heat during EUV exposure.

[0072] In some embodiments, the diffusion barrier layer 260 may be a single layer of carbon-based material. In some other embodiments, the diffusion barrier layer 260 may include multiple layers of carbon-based material. In some embodiments, the diffusion barrier layer 260 may include 1 to 10 layers of carbon-based material. In some embodiments, the diffusion barrier layer 260 may be a single graphene layer (e.g., a single atomic layer thick graphene layer). In some other embodiments, the diffusion barrier layer may include two or more graphene layers. In some embodiments, the thickness of the diffusion barrier layer 260 is in the range of about 0.2 nm to 5 nm. When the thickness of the diffusion barrier layer 260 exceeds this range, the EUV transmittance of the pellicle may be reduced. On the contrary, when the thickness of the diffusion barrier layer 260 is below this range, the diffusion barrier layer 260 may not be able to effectively prevent the migration of the nanostructure due to insufficient heat dissipation.

[0073] The diffusion barrier layer 260 may be formed by a suitable deposition technique such as CVD or PECVD. In some embodiments, when the diffusion barrier layer 260 is made of graphene, the diffusion barrier layer 260 may be formed by CVD using the nanostructures 252 as a catalyst. In some embodiments, the diffusion barrier layer 260 is formed as a conformal layer around the exposed surface of the nanostructures 252.

[0074] The capping layer 270 covers both the diffusion barrier layer 260 and the CNT 230 as a conformal layer. Since the nanostructures 252 and the diffusion barrier layer 260 only partially cover the surface of the CNT 230, the capping layer 270 is in contact with both the surface of the CNT 230 and the surface of the diffusion barrier layer 260. The capping layer 270 is adapted to prevent hydrogen penetration, thereby protecting the CNT 230 and the diffusion barrier layer 260 from damage by hydrogen radicals. In some embodiments, the capping layer 270 may include a dielectric material, for example, a dielectric oxide, such as silicon dioxide (SiO2), aluminum oxide (Al2O3), niobium oxide (Nb2O5), platinum dioxide (PtO2), ruthenium oxide (RuO2), titanium oxide (TiO2), or yttrium oxide (Y2O3); a dielectric nitride, such as silicon nitride (SiN), aluminum nitride (AlN), titanium nitride (TiN), yttrium nitride (YN), or boron nitride (BN); a dielectric oxynitride, such as silicon oxynitride (SiON), aluminum oxynitride (AlON), or titanium oxynitride (TiON); a dielectric carbide, such as silicon carbide (SiC); a dielectric oxycarbide, such as silicon oxycarbide (SiOC); or a dielectric oxysilicide, such as yttrium oxysilicide (YOSi).

[0075] The capping layer 270 is very thin and therefore does not reduce the transmittance of the pellicle membrane 226 to EUV light. In some embodiments, the thickness of the capping layer 270 can be in the range of about 1 nm to about 5 nm. The capping layer 270 can be formed by a suitable conformal deposition technique (such as CVD, PECVD, ALD, thermal ALD, or PVD). In some embodiments, the capping layer 270 is formed in the form of a conformal layer around the CNT 230. In some embodiments, the capping layer 270 can be a single layer. In some other embodiments, the capping layer 270 can be composed of multiple layers, each layer being made of the above-mentioned different materials.

[0076] Figure 3B is a cross-sectional view of a second example of a coated CNT 300 in a network of multiple CNTs according to some embodiments. Figure 3BAs shown, the protective coating 240 surrounding the CNT 230 includes a seed layer 250, the seed layer 250 includes a plurality of nanostructures 252 on the CNT 230 and partially covering the surface of the CNT 230, a diffusion barrier layer 260 on the nanostructures 252 and the CNT 230, and a capping layer 270 on the diffusion barrier layer 260. Figure 3A Unlike the first example shown (diffusion barrier layer 260 is formed as a discontinuous layer covering only nanostructures 252), in the second example, diffusion barrier layer 260 is formed as a continuous conformal layer that covers not only nanostructures 252 but also portions of CNTs 230 not covered by nanostructures 252. Therefore, the capping layer 270 formed subsequently contacts only the diffusion barrier layer 260. In some embodiments, the continuous diffusion barrier layer 260 may be formed by a conformal deposition process such as CVD or PECVD.

[0077] Figure 3C is a cross-sectional view of a third example of a coated CNT 300 in a network of multiple CNTs according to some embodiments. Figure 3C As shown, the protective coating 240 surrounding the CNT 230 includes a seed layer 250 on the surface of the CNT 230, a diffusion barrier layer 260 on the seed layer 250, and a capping layer 270 on the diffusion barrier layer 260 and the CNT 230. Figure 3AUnlike the first example shown (the seed layer 250 includes a single type of nanostructure 252 made of the same material), in the third example, the seed layer 250 includes two types of nanostructures, namely, a plurality of first nanostructures 252 and a plurality of second nanostructures 254 made of different materials. The first nanostructure 252 and the second nanostructure 254 can be nanograins, nanoislands, nanocubes, nanosheets, or a combination thereof. In some embodiments, the first nanostructure 252 and the second nanostructure 254 are uniformly distributed on the surface of the CNT 230, so that the spacing between adjacent nanostructures 252, 254 is the same. In some embodiments, the first and second nanostructures 252, 254 are randomly distributed on the surface of the CNT 230, so that the spacing between adjacent nanostructures 252, 254 is different. In some embodiments, the first nanostructure 252 and the second nanostructure 254 are arranged so that one or more first nanostructures 252 are separated from one or more first nanostructures 252 by one or more second nanostructures 254. In some embodiments, the first nanostructure 252 and the second nanostructure 254 are arranged such that the first nanostructures 252 are separated from each other by one or more second nanostructures 254. The sizes of the first nanostructure 252 and the second nanostructure 254 are selected so that the first nanostructure 252 and the second nanostructure 254 do not block the transmission of EUV light. In some embodiments, the first nanostructure 252 and the second nanostructure 254 may independently have a size in the range of about 0.5 nm to about 5 nm. In some embodiments, the first nanostructure 252 and the second nanostructure 254 have the same size. In some embodiments, the first nanostructure 252 may have different morphologies, so that the cross-sectional profiles of the first nanostructure 252 are different from each other. In some embodiments, the second nanostructure 254 may have different morphologies, so that the cross-sectional profiles of the second nanostructure 254 are different from each other. In some embodiments, the profile of the first nanostructure 252 may be the same as or different from the profile of the second nanostructure 254.

[0078] In some embodiments, the first nanostructure 252 and the second nanostructure 254 are independently composed of a transition metal or a compound thereof. Examples of suitable transition metals include, but are not limited to, chromium (Cr), cobalt (Co), copper (Cu), iridium (Ir), iron (Fe), gold (Au), manganese (Mn), molybdenum (Mo), nickel (Ni), niobium (Nb), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), silver (Ag), tantalum (Ta), titanium (Ti), tungsten (W), vanadium (V), and zirconium (Zr). In some embodiments, the compound may include an oxide, nitride, silicide, or carbide of a transition metal. In some embodiments, the first nanostructure 252 and the second nanostructure 254 independently include Co, Ir, Fe, Nb, Ni, Pt, Rh, Ru, Ti, RuO2, RuSi2, RuSi, Ru2Si3, Nb2O5, Mo, MoO2, or TiO2. In some embodiments, the first nanostructure 252 includes Ru, RuO2, RuSi2, RuSi, or Ru2Si3, and the second nanostructure 254 includes Nb, Nb2O5, Mo, MoO2, Ti, TiO2, Ir, Pt, Rh, Ni, Fe, or Co. In some embodiments, the first nanostructure 252 includes Ru or RuO2, and the second nanostructure 254 includes Ir or Pt. In a third example, using two types of nanostructures made of different materials can simultaneously optimize hydrogen reduction and EUV transmission.

[0079] In the third example, since the seed layer 250 includes two types of nanostructures (ie, the first nanostructure 252 and the second nanostructure 254 ), the diffusion barrier layer 260 encapsulates both the first nanostructure 252 and the second nanostructure 354 .

[0080] Figure 3D is a cross-sectional view of a fourth example of a coated CNT 300 in a network of multiple CNTs according to some embodiments. Figure 3D As shown, the protective coating 240 surrounding the CNT 230 includes a seed layer 250 including a plurality of first nanostructures 252 and a plurality of second nanostructures 254 on the surface of the CNT 230, a diffusion barrier layer 260 on the seed layer 250 and the CNT 230, and a capping layer 270 on the diffusion barrier layer 260. Figure 3C Unlike the third example shown (in which the diffusion barrier layer 260 is formed as a non-continuous layer covering only the first nanostructure 252 and the second nanostructure 254), in the fourth example, the diffusion barrier layer 260 is formed as a continuous conformal layer that not only covers the first nanostructure 252 and the second nanostructure 254, but also covers the portions of the CNT 230 that are not covered by the first nanostructure 252 and the second nanostructure 254.

[0081] Figure 4 4 is a flow chart illustrating a method 400 for assembling a pellicle for a photolithography process according to some embodiments. For example, the method 400 may be performed to assemble Figure 1 and Figure 2A-2B The protective film 114 is shown in FIG. The method 400 may be performed using one or more different machines under the control of a controller or processor. Figures 5A-5E 4 is a cross-sectional view of a protective film 500 at various stages of method 400 according to some embodiments. Figures 5A-5E The illustrated overcoat 500 discusses the method 400 in detail.

[0082] In step 402 of method 400, a CNT film layer 510 including a plurality of CNTs 230 may be constructed on a support film 502, such as Figure 5A As shown. The plurality of CNTs 230 may include a plurality of individual CNTs or a plurality of CNT bundles. The CNTs may be single-walled, double-walled, multi-walled CNTs, or a combination thereof. The support film 502 may include, for example, polyvinyl alcohol (PVA), polystyrene (PS), polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), or a chemical vapor deposited polyparaxylene polymer (e.g., parylene C). In some embodiments, the CNT film layer 510 may be constructed using a roll-to-roll process in a plasma environment (such as a plasma reaction chamber), in which the reaction gas may include, for example, C x H y , H2, Ar, O2, another suitable gas, or any combination thereof.

[0083] In step 404 of method 400, a protective coating is formed around at least one CNT 230 of the plurality of CNTs 230, thereby forming a protective film sheet 226 including a plurality of coated CNTs 300, such as Figure 5B The processing steps for forming a protective coating on CNT 230 will be described in detail below.

[0084] In step 406 of method 400, border 224 is attached to pellicle membrane 226 along a peripheral portion of pellicle membrane 226, such as Figure 5CAs shown. In some embodiments, the border 224 can be rectangular. In order to attach the border 224 to the pellicle membrane 226, in some embodiments, the border 224 is first brought into physical contact with the pellicle membrane 226. Then, the border 224 is pressed against the pellicle membrane 226 to fix the pellicle membrane 226 to the border 224. In some embodiments, the border 224 and the pellicle membrane 226 are held together by van der Waals forces. In some embodiments, to ensure better adhesion, an adhesive is used to attach the border 224 to the pellicle membrane 226.

[0085] In step 408 of method 400, the support membrane 502 is removed to make the protective membrane 226 independent, such as Figure 5D In some embodiments, when the supporting film 502 is made of an organic material, the supporting film 502 can be removed by wet etching using an organic solvent.

[0086] In step 410 of method 400, the border 224 and the pellicle membrane 226 are attached to the pellicle frame 206 including the vent structure. Figure 5E As shown, the pellicle frame 206 may have the same shape as the border 224 (eg, rectangular).

[0087] Figure 6 is a flow chart illustrating a method 600 of forming a protective coating 240 on a CNT 230 according to some embodiments. Figures 7A-7D ' is a cross-sectional view of a coated CNT 300 at various stages of method 600 according to some embodiments. Figures 7A-7D 'The coated CNT 300 shown is discussed in detail in method 600.

[0088] In step 602 of method 600, a surface treatment is performed to form functional groups 232 on the CNT surface, such as Fig. 7A As shown. Functional group 232 can serve as a reaction site for forming nanostructure 252. In some embodiments, functional group 232 includes hydroxyl (-OH) group, carbonyl (-C=O) group, sulfhydryl group, carboxyl group, amino group, phosphate group or a combination thereof. In some embodiments, functional group 232 can be randomly formed on the surface of CNT 230. In some embodiments, functional group 232 can be uniformly formed on the surface of CNT 230.

[0089] In some embodiments, the surface treatment includes applying a solution to the CNT film, or soaking or immersing the CNT film layer in a solution. The solution may include an organic or inorganic acid solution, and / or a polymer or organic compound having one or more of the functional groups. In some embodiments, the solution includes HNO3, H2SO4, 5-isocyanate-isophthalic acid chloride (ICIC), dodecylamine (DDA), polycaprolactone (PCL), polyacrylic acid (PAA), polydopamine (Pdop), polyaniline (PANI), polymethyltriethylammonium chloride (PMTAC), poly(ethylene glycol) methyl ether methacrylate (PEGMA), polymethacrylic acid sulfobetaine (PSBMA), 3-aminopropyltriethoxysilane (APTS), 1,3-phenylenediamine (mPDA) or a combination thereof. In some embodiments, the solution includes HNO3, H2SO4, H2SO4 / HNO3, HCl / H2SO4 / HNO3, H2O2, KMnO4, K2Cr2O7 / H2SO4, or KMnO4 / H2SO4.

[0090] In some embodiments, the surface treatment includes gas soaking by applying one or more gases to the CNT film layer. In some embodiments, the CNT film layer and / or the gas are heated in a temperature range of about 300°C to 1200°C. In other embodiments, the temperature range is about 600°C to 800°C. When the temperature is too high, the film may be damaged, and when the temperature is too low, the surface modification may be insufficient. The soaking gas includes one or more of Ar, He, H2, Ne, N2 and NH3, and does not contain oxygen. In some embodiments, O2 may be used alternatively or additionally.

[0091] In some embodiments, the surface treatment includes plasma treatment of the CNT film layer. The plasma gas includes one or more of Ar, He, H2, Ne, N2 and NH3, without oxygen. In some embodiments, O2 may be used alternatively or additionally. In some embodiments, the CNT film layer and / or gas is heated at a temperature range of about 200°C to 600°C during the plasma treatment. In other embodiments, the temperature range is about 300°C to 500°C. The plasma is generated in the form of capacitively coupled plasma, inductively coupled plasma, electron cyclotron plasma, mixed cold plasma, glow discharge plasma or high pressure arc plasma. In some embodiments, the input power of the plasma ranges from about 1W to about 2kW.

[0092] In some embodiments, hydroxyl or carbonyl functional groups 232 are formed on the surface of CNTs 230 by H 2 O plasma or hot H 2 O 2 .

[0093] In some embodiments, one or more post-treatments may be performed after the surface treatment. In some embodiments, the post-treatment includes annealing, such as furnace annealing, rapid thermal annealing, laser annealing, UV annealing, or electron beam annealing.

[0094] In step 604 of method 600, a seed layer 250 including a plurality of nanostructures 252 is formed on the surface of CNT 230, such as Figure 7B As shown. Nanostructure 252 is formed at the site where functional group 232 is located. Functional group 232 serves as a nucleation center to initiate the growth of nanostructure 252. Nanostructure 252 can be nanograins, nanoislands, nanocubes, nanosheets, or a combination thereof, and can be formed by sol-gel process, electron beam evaporation, CVD, ALD, PEALD, electrodeposition, electroless deposition, or other suitable deposition techniques.

[0095] In step 606 of method 600, a diffusion barrier layer 260 is deposited on at least the nanostructures 252, such as Figure 7C or Figure 7C In some embodiments, the deposition of the diffusion barrier layer 260 is catalyzed by the nanostructures 252. In some embodiments, as Figure 7C As shown, the diffusion barrier layer 260 is deposited to cover only the nanostructures 252, while the portion of the CNT 230 between the nanostructures 252 is not covered by the diffusion barrier layer 260. Figure 7C As shown, the diffusion barrier layer 260 is deposited on both the nanostructures 252 and the CNTs 230, so that the portion of the CNTs 230 between the nanostructures 252 is also covered by the diffusion barrier layer 260. In some embodiments, the diffusion barrier layer 260 is formed in the form of a conformal layer and is deposited by a conformal deposition process such as CVD or PECVD.

[0096] In step 608 of method 600, a capping layer 270 is deposited on at least the diffusion barrier layer 260, such as Fig.7D or Fig.7D ' As shown. In the case where the diffusion barrier layer 260 is formed only on the nanostructure 252 ( Figure 7C ), the capping layer 270 is formed in contact with the diffusion barrier layer 260 and the CNT 230, such as Fig.7D In the case where the diffusion barrier layer 260 is formed on both the nanostructure 252 and the CNT 230 ( Figure 7C '), the capping layer 270 is formed only in contact with the diffusion barrier layer 260, such as Fig.7DIn some embodiments, the capping layer 270 is formed in the form of a conformal layer and is deposited by a conformal deposition process such as CVD, PECVD, ALD, PEALD, thermal ALD, or PVD.

[0097] Figure 8 is a flow chart illustrating a method 800 of forming a protective coating 240 on a CNT 230 according to some embodiments. Figures 9A-9E ' is a cross-sectional view of a coated CNT 300 at various stages of method 800 according to some embodiments. Figures 9A-9E 'The coated CNT 300 shown is discussed in detail in method 800.

[0098] In step 802 of method 800, a surface treatment is performed to form functional groups 232 on the CNT surface, such as Fig. 9A As described above in step 602 of method 600, surface treatment may be performed using various methods (such as using a solution, a gas, or a plasma).

[0099] In step 804 of method 800, a plurality of first nanostructures 252 are formed on the surface of CNT 230, such as Fig. 9B As shown. The first nanostructure 252 is formed at the site where the first subset of functional groups 232 is located. The first nanostructure 252 can be a nanograin, a nanoisland, a nanocube, a nanosheet, or a combination thereof, and can be formed by a sol-gel process, electron beam evaporation, CVD, ALD, PEALD, electrodeposition, electroless deposition, or other suitable deposition techniques.

[0100] In step 806 of method 800, a plurality of second nanostructures 254 are formed on the surface of CNT 230, such as Fig. 9C As shown. The second nanostructure 254 is formed at the site where the second subset of functional groups 232 is located. The second nanostructure 254 is composed of a material different from that of the first nanostructure 252. The second nanostructure 254 can be a nanograin, a nanoisland, a nanocube, a nanosheet, or a combination thereof, and can be formed by a sol-gel process, electron beam evaporation, CVD, ALD, PEALD, electrodeposition, electroless deposition, or other suitable deposition techniques. The second nanostructure 254 forms a seed layer 250 together with the first nanostructure 252.

[0101] In the embodiment of the present application, using two types of nanostructures (ie, nanostructures 252 , 254 ) made of different materials can simultaneously optimize the hydrogen reduction capability and EUV light transmission characteristics of these nanostructures.

[0102] In step 808 of method 800, a diffusion barrier layer 260 is deposited on at least the first nanostructure 252 and the second nanostructure 254, such as Fig.9D or Fig.9D In some embodiments, the deposition of the diffusion barrier layer 260 is catalyzed by the first nanostructure 252 and the second nanostructure 254. In some embodiments, as Fig.9D As shown, the diffusion barrier layer 260 is deposited to cover only the first nanostructure 252 and the second nanostructure 254, so that the portion of the CNT 230 between the first nanostructure 252 and the second nanostructure 254 is not covered by the diffusion barrier layer 260. Fig.9D As shown in FIG. 1 , the diffusion barrier layer 260 is deposited on the first nanostructure 252, the second nanostructure 254 and the CNT 230, so that the portion of the CNT 230 between the first and second nanostructures 252, 254 is also covered by the diffusion barrier layer 260. In some embodiments, the diffusion barrier layer 260 is formed in the form of a conformal layer and is deposited by a conformal deposition process such as CVD or PECVD.

[0103] In step 810 of method 800, a capping layer 270 is deposited on at least the diffusion barrier layer 260, such as Fig.9E or Fig.9E ' As shown. In the case where the diffusion barrier layer 260 is formed only on the first nanostructure 252 and the second nanostructure 254 ( Fig.9D ), the capping layer 270 is formed in contact with the diffusion barrier layer 260 and the CNT 230, such as Fig.9E In the case where the diffusion barrier layer 260 is formed on the first nanostructure 252 and the second nanostructure 254 and the CNT 230 ( Fig.9D '), the capping layer 270 is formed only in contact with the diffusion barrier layer 260, such as Fig.9E In some embodiments, the capping layer 270 is formed in the form of a conformal layer and is deposited by a conformal deposition process such as CVD, PECVD, ALD, PEALD, thermal ALD, or PVD.

[0104] Fig.10 is a flow chart illustrating a method 1000 of fabricating a semiconductor device according to some embodiments. Figures 11A-11D is a cross-sectional view of a semiconductor device 1100 at various stages of method 1000 according to some embodiments. Figures 11A-11D The method 1000 is discussed in detail with reference to the semiconductor device shown. At least some steps of the method 1000 may be performed by controlling an EUV lithography system (such as, Figure 1 The lithography system shown is used for execution.

[0105] A semiconductor substrate or other suitable substrate to be patterned is provided to form an integrated circuit thereon. In some embodiments, the semiconductor substrate comprises silicon. Alternatively or additionally, the semiconductor substrate further comprises germanium, silicon germanium or other suitable semiconductor materials, such as, III-V semiconductor materials.

[0106] In step 1002 of the method 1000, a target layer 1120 to be patterned is formed on a semiconductor substrate 1110, such as Fig.11A As shown. In some embodiments, the target layer 1120 is a semiconductor substrate 1110. In some embodiments, the target layer 1120 includes a conductive layer, such as a metal layer or a polysilicon 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 1120 is formed on an underlying structure (such as an isolation structure, a transistor, or wiring).

[0107] In step 1004 of method 1000, a photoresist layer 1130 is formed on the target layer 1120, such as Fig.11A As shown. The photoresist layer 1130 is sensitive to radiation from an exposure source during a subsequent photolithography exposure process. In some embodiments, the photoresist layer 1130 is sensitive to EUV light used in the photolithography exposure process. The photoresist layer 1130 can be formed on the target layer by spin coating or other suitable techniques. The coated photoresist layer 1030 can be further baked to drive out the solvent in the photoresist layer 1130.

[0108] In step 1006 of method 1000, the photoresist layer 1130 is patterned using the EUV mask 1040 with the pellicle 1150 described above, such as Fig. 11BAs shown. The pellicle 1150 includes the pellicle film described herein. The pellicle film includes at least one CNT film layer, which contains a network of multiple CNTs, wherein at least one of the multiple CNTs is coated with a multilayer protective coating of the present application. The patterning of the photoresist layer 1130 includes performing a photolithography exposure process using an EUV photomask 1140 by an EUV exposure system. During the exposure process, light emitted by the EUV light source is directed onto the EUV photomask 1140. Then, the projection optics module collects light that passes through the pellicle 1150 and is reflected by the EUV photomask 1140, and directs it to the photoresist layer 1130. The integrated circuit (IC) design pattern defined on the EUV photomask 1140 is imaged onto the photoresist layer 1130 to form a latent pattern thereon. Particles dropped during the exposure process may be captured by the pellicle sheet 226 so that the EUV photomask 1140 is not affected by the dropped particles when light is directed onto the EUV photomask 1140 .

[0109] The patterning of the photoresist layer 1130 also includes developing the exposed photoresist layer to form a patterned photoresist layer 1130P having a plurality of openings 1135. In one embodiment where the photoresist layer 1130 is a positive tone photoresist layer, the exposed portion of the photoresist layer 1130 is removed during the development process. The patterning of the photoresist layer 1130 may also include other process steps, such as various baking steps at different stages. For example, a post-exposure bake (PEB) process may be implemented after the photolithography exposure process and before the development process.

[0110] In step 1008 of method 1000, the target layer 1120 is patterned using the patterned photoresist layer 1130P as an etching mask, such as Fig. 11C As shown. In some embodiments, patterning of the target layer 1120 includes applying an etching process to the target layer 1120 using the patterned photoresist layer 1130P as an etching mask. The portion of the target layer 1120 exposed within the opening 1135 of the patterned photoresist layer 1030P is etched away, while the remaining portion is protected from etching. A groove 1125 now appears in the patterned target layer 1120P.

[0111] In step 1010 of method 1000, the patterned photoresist layer 1130P may be removed by wet stripping or plasma ashing, such as Fig.11D Further processing steps can then be performed.

[0112] One aspect of the present specification relates to a protective film. The protective film includes a protective film sheet containing a plurality of carbon nanotubes (CNTs). At least one carbon nanotube (CNT) among the plurality of CNTs is coated with a protective coating. The protective coating includes a plurality of first nanostructures on the surface of at least one CNT among the plurality of CNTs, a carbon-based diffusion barrier layer on at least the plurality of first nanostructures, and a capping layer on at least the carbon-based diffusion barrier layer. The plurality of first nanostructures include transition metals or their oxides, nitrides, silicides or carbides. The protective film sheet also includes a protective film boundary attached to the protective film sheet along a peripheral area of ​​the protective film sheet; and a protective film frame attached to the protective film boundary.

[0113] Another aspect of the present description relates to a pellicle-photomask structure. The pellicle-photomask structure includes an extreme ultraviolet (EUV) photomask, the extreme ultraviolet (EUV) photomask including a pattern region and a pellicle attached to a peripheral region of the EUV photomask, the pellicle including a pellicle film sheet extending across the pattern region of the EUV photomask. The pellicle film sheet includes a plurality of carbon nanotubes (CNTs) covered by a protective coating. The protective coating includes a plurality of first nanostructures on a surface of at least one CNT of the plurality of CNTs, a carbon-based diffusion barrier layer on the plurality of first nanostructures, and a capping layer on the carbon-based diffusion barrier layer.

[0114] Yet another aspect of the present specification relates to a method for forming a protective film for protecting an extreme ultraviolet (EUV) photomask, the method comprising forming a plurality of functional groups on the surface of a plurality of carbon nanotubes (CNTs), growing a plurality of nanostructures on the surface of the plurality of CNTs using the plurality of functional groups as nucleation sites, forming a carbon-based diffusion barrier layer to encapsulate the plurality of nanostructures, and forming a conformal capping layer covering the carbon-based diffusion barrier layer and the plurality of CNTs.

[0115] The present application also includes the following exemplary embodiments:

[0116] Embodiment 1. A protective film, comprising:

[0117] A protective membrane sheet comprising a plurality of carbon nanotubes (CNTs), wherein at least one carbon nanotube (CNT) of the plurality of CNTs is coated with a protective coating, the protective coating comprising:

[0118] a plurality of first nanostructures on a surface of at least one CNT of the plurality of CNTs, the plurality of first nanostructures comprising a transition metal or an oxide, nitride, silicide or carbide thereof;

[0119] a carbon-based diffusion barrier layer over at least the plurality of first nanostructures; and

[0120] a capping layer over at least the carbon-based diffusion barrier layer; and

[0121] a pellicle border attached to the pellicle membrane along a peripheral region of the pellicle membrane; and

[0122] A pellicle frame is attached to the pellicle border.

[0123] Embodiment 2. A protective film according to embodiment 1, wherein the protective coating further comprises a plurality of second nanostructures on the surface of at least one carbon nanotube among the plurality of carbon nanotubes, the plurality of second nanostructures comprising a transition metal or an oxide thereof, wherein the plurality of first nanostructures and the plurality of second nanostructures are composed of different materials.

[0124] Embodiment 3. A protective film according to embodiment 2, wherein the plurality of first nanostructures and the plurality of second nanostructures independently include Co, Ir, Fe, Nb, Ni, Pt, Rh, Ru, Ti, RuO2, RuSi2, RuSi, Ru2Si3, Nb2O5, Mo, MoO2 or TiO2.

[0125] Embodiment 4. The overcoat according to embodiment 3, wherein the plurality of first nanostructures include Ru or RuO 2 , and the plurality of second nanostructures include Ir or Pt.

[0126] Embodiment 5. The overcoat according to embodiment 2, wherein the plurality of first nanostructures and the plurality of second nanostructures are nanograins, nanoislands, nanocubes, nanosheets, or a combination thereof.

[0127] Embodiment 6. The overcoat of embodiment 1, wherein the carbon-based diffusion barrier layer comprises graphene, amorphous carbon, graphite, or diamond-like carbon.

[0128] Embodiment 7. The overcoat of embodiment 6, wherein the carbon-based diffusion barrier layer comprises graphene.

[0129] Embodiment 8. The pellicle of embodiment 1, wherein the capping layer is a conformal layer in contact with the carbon-based diffusion barrier layer and a portion of at least one CNT in the plurality of CNTs that is not covered by the carbon-based diffusion barrier layer.

[0130] Embodiment 9. A protective film according to embodiment 8, wherein the capping layer includes silicon dioxide (SiO2), aluminum oxide (Al2O3), niobium oxide (Nb2O5), platinum dioxide (PtO2), ruthenium oxide (RuO2), titanium oxide (TiO2), yttrium oxide (Y2O3), silicon nitride (SiN), aluminum nitride (AlN), titanium nitride (TiN), yttrium nitride (YN), boron nitride (BN), silicon oxynitride (SiON), aluminum oxynitride (AlON), titanium oxynitride (TiON), silicon carbide (SiC), silicon oxycarbide (SiOC) or yttrium oxysilicide (YOSi).

[0131] Embodiment 10. A pellicle-photomask structure, comprising:

[0132] an extreme ultraviolet (EUV) photomask including a patterned area; and

[0133] a pellicle attached to a peripheral region of the EUV photomask, the pellicle comprising a pellicle membrane sheet extending across a pattern region of the EUV photomask, the pellicle membrane sheet comprising a plurality of carbon nanotubes (CNTs), wherein the plurality of CNTs are covered by a protective coating, the protective coating comprising:

[0134] a plurality of first nanostructures on a surface of at least one CNT in the plurality of CNTs;

[0135] a carbon-based diffusion barrier layer over the plurality of first nanostructures; and

[0136] A capping layer is over the carbon-based diffusion barrier layer.

[0137] Embodiment 11. A protective film-photomask structure according to embodiment 10, wherein the protective coating further comprises a plurality of second nanostructures on the surface of at least one CNT among the plurality of CNTs, the plurality of first nanostructures comprising a first material, and the plurality of second nanostructures comprising a second material different from the first material.

[0138] Embodiment 12. The pellicle-photomask structure of embodiment 11, wherein the first nanostructures are separated from each other by one or more of the second nanostructures.

[0139] Embodiment 13. A pellicle-photomask structure according to embodiment 11, wherein the plurality of first nanostructures include Ru, RuO2, RuSi2, RuSi or Ru2Si3, and the plurality of second nanostructures include Nb, Nb2O5, Mo, MoO2, Ti, TiO2, Ir, Pt, Rh, Ni, Fe or Co.

[0140] Embodiment 14. The pellicle-photomask structure of Embodiment 10, wherein the carbon-based diffusion barrier layer comprises graphene.

[0141] Embodiment 15. The pellicle-photomask structure of embodiment 10, wherein the carbon-based diffusion barrier layer is a non-continuous layer present only on exposed surfaces of the plurality of first nanostructures.

[0142] Embodiment 16. The pellicle-photomask structure of Embodiment 10, wherein the carbon-based diffusion barrier layer is a continuous conformal layer present on exposed surfaces of the plurality of CNTs and the plurality of first nanostructures.

[0143] Embodiment 17. A protective film-photomask structure according to embodiment 10, wherein the capping layer includes silicon dioxide (SiO2), aluminum oxide (Al2O3), niobium oxide (Nb2O5), platinum dioxide (PtO2), ruthenium oxide (RuO2), titanium oxide (TiO2), yttrium oxide (Y2O3), silicon nitride (SiN), aluminum nitride (AlN), titanium nitride (TiN), yttrium nitride (YN), boron nitride (BN), silicon oxynitride (SiON), aluminum oxynitride (AlON), titanium oxynitride (TiON), silicon carbide (SiC), silicon oxycarbide (SiOC) or yttrium oxysilicide (YOSi).

[0144] Embodiment 18. A method for forming a pellicle for protecting an extreme ultraviolet (EUV) photomask, the method comprising the steps of:

[0145] forming a plurality of functional groups on surfaces of a plurality of carbon nanotubes (CNTs);

[0146] growing a plurality of nanostructures on surfaces of the plurality of CNTs using the plurality of functional groups as nucleation sites;

[0147] forming a carbon-based diffusion barrier layer to encapsulate the plurality of nanostructures; and

[0148] A conformal capping layer is formed covering the carbon-based diffusion barrier layer and the plurality of CNTs.

[0149] Embodiment 19. The method of embodiment 18, wherein the plurality of functional groups comprises hydroxyl or carbonyl groups.

[0150] Embodiment 20. The method of embodiment 18, wherein forming the plurality of functional groups comprises surface treatment using H2O plasma or thermal H2O2.

[0151] The features of several embodiments are summarized above so that those skilled in the art can better understand the various aspects of the present application. It should be understood by those skilled in the art that they can easily design or modify other processes and structures based on the present application to achieve the same purpose and / or achieve the same advantages of the embodiments introduced herein. It should also be recognized by those skilled in the art that such equivalent constructions do not deviate from the spirit and scope of the present application, and they can make various changes, substitutions and modifications to this article without departing from the spirit and scope of the present application.

Claims

1. A protective film, comprising: A protective membrane sheet comprising a plurality of carbon nanotubes (CNTs), wherein at least one carbon nanotube (CNT) of the plurality of CNTs is coated with a protective coating, the protective coating comprising: a plurality of first nanostructures on a surface of at least one CNT of the plurality of CNTs, the plurality of first nanostructures comprising a transition metal or an oxide, nitride, silicide or carbide thereof; a carbon-based diffusion barrier layer over at least the plurality of first nanostructures; and a capping layer over at least the carbon-based diffusion barrier layer; and a pellicle border attached to the pellicle membrane along a peripheral region of the pellicle membrane; and A pellicle frame is attached to the pellicle border.

2. The protective film according to claim 1, wherein: The protective coating further includes a plurality of second nanostructures on a surface of at least one of the plurality of carbon nanotubes, the plurality of second nanostructures comprising a transition metal or an oxide thereof, wherein the plurality of first nanostructures and the plurality of second nanostructures are composed of different materials.

3. The protective film according to claim 2, wherein: The plurality of first nanostructures and the plurality of second nanostructures independently include Co, Ir, Fe, Nb, Ni, Pt, Rh, Ru, Ti, RuO2, RuSi2, RuSi, Ru2Si3, Nb2O5, Mo, MoO2 or TiO2.

4. The protective film according to claim 3, wherein: The plurality of first nanostructures include Ru or RuO 2 , and the plurality of second nanostructures include Ir or Pt.

5. The protective film according to claim 2, wherein: The plurality of first nanostructures and the plurality of second nanostructures are nanograins, nanoislands, nanocubes, nanosheets, or a combination thereof.

6. The protective film according to claim 1, wherein: The carbon-based diffusion barrier layer includes graphene, amorphous carbon, graphite or diamond-like carbon.

7. The protective film according to claim 1, wherein: The capping layer is a conformal layer in contact with the carbon-based diffusion barrier layer and a portion of at least one CNT among the plurality of CNTs that is not covered by the carbon-based diffusion barrier layer.

8. The protective film according to claim 7, wherein: The capping layer includes silicon dioxide (SiO2), aluminum oxide (Al2O3), niobium oxide (Nb2O5), platinum dioxide (PtO2), ruthenium oxide (RuO2), titanium oxide (TiO2), yttrium oxide (Y2O3), silicon nitride (SiN), aluminum nitride (AlN), titanium nitride (TiN), yttrium nitride (YN), boron nitride (BN), silicon oxynitride (SiON), aluminum oxynitride (AlON), titanium oxynitride (TiON), silicon carbide (SiC), silicon oxycarbide (SiOC) or yttrium oxide siliconide (YOSi).

9. A pellicle-photomask structure, comprising: an extreme ultraviolet (EUV) photomask including a patterned area; as well as a pellicle attached to a peripheral region of the EUV photomask, the pellicle comprising a pellicle membrane sheet extending across a pattern region of the EUV photomask, the pellicle membrane sheet comprising a plurality of carbon nanotubes (CNTs), wherein the plurality of CNTs are covered by a protective coating, the protective coating comprising: a plurality of first nanostructures on a surface of at least one CNT in the plurality of CNTs; a carbon-based diffusion barrier layer over the plurality of first nanostructures; and A capping layer is over the carbon-based diffusion barrier layer.

10. A method for forming a pellicle for protecting an extreme ultraviolet (EUV) photomask, the method comprising the steps of: forming a plurality of functional groups on surfaces of a plurality of carbon nanotubes (CNTs); growing a plurality of nanostructures on surfaces of the plurality of CNTs using the plurality of functional groups as nucleation sites; forming a carbon-based diffusion barrier layer to encapsulate the plurality of nanostructures; as well as A conformal capping layer is formed covering the carbon-based diffusion barrier layer and the plurality of CNTs.

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