ROBUST, HIGH-PERMISSION MEMBRANE FOR LITHOGRAPHIC EXTREMES ULTRAVIOLET SYSTEMS

Abstract

Membrane (114) with: a film (226), wherein the film (226) comprises at least one layer selected from the group consisting of a transparent carbon-based layer and a transparent silicon-based layer, wherein the at least one layer is coated with a protective sheath (232) that dissipates heat from the film (226); and a frame (206) supporting the film (226), the frame (206) having at least one hole to allow air flow through a portion of the membrane (114); the transparent carbon-based layer comprising a network of carbon nanotubes; wherein the transparent silicon-based layer comprises a network of silicon nanowires; wherein the film (226) has a thickness of 20 nm to 50 nm and transmits more than 82% of extreme ultraviolet radiation, EUV radiation.

Description

background

[0001] EUV lithography (EUV: extreme ultraviolet) is a photolithography process in which a scanner uses light in the extreme ultraviolet range (e.g., wavelengths from approximately 1 nm to 100 nm). A light source is configured to emit EUV radiation. For example, the light source can sputter a molten metal, such as tin, into a highly ionized plasma that emits EUV radiation. The EUV radiation is then directed into the scanner using a series of optical devices (e.g., multilayer mirrors). Within the scanner, the EUV radiation is used to project a pattern etched into a photomask onto a silicon wafer. The EUV process can be used to produce high-resolution line patterns on the silicon wafer, potentially on the order of 7 nm or smaller.

[0002] US 2019 / 0 137 865 A1 describes a membrane with aeration structures. US 2017 / 0 038 676 A1 shows a membrane comprising a porous thin film with nanowires. US 2018 / 0 329 289 A1 discusses a method for forming a membrane from carbon nanotubes. Short description of the drawings

[0003] Aspects of the present invention can best be understood from the following detailed description when taken in conjunction with the accompanying drawings. It should be noted that, in accordance with standard industry practice, various elements are not drawn to scale. Rather, for the sake of clarity of discussion, the dimensions of various elements may be exaggerated or reduced as desired. Fig. 1 is a simplified schematic representation of an exemplary lithographic system according to examples of the present invention. Fig. 2A is a cross-sectional view of an exemplary membrane photomask structure according to examples of the present invention. Fig. Figure 2B is an isometric view of the exemplary membrane photomask structure of Fig. 2A. Fig. 2C shows an exemplary upper film part of the membrane film of the Fig. 2A and Fig. 2B. Fig. 2D shows an example cross-sectional view of an exemplary carbon nanotube of the carbon nanotube network of Fig. 2C. Fig. 3 is a flow diagram illustrating a method 300 for assembling a membrane for a lithographic process according to an example of the present invention. Fig. 4 shows a flowchart of a method for manufacturing a semiconductor device according to at least one embodiment of the present invention. Detailed description

[0004] The following description provides many different embodiments or examples for implementing various features of the provided subject matter. Specific examples of components and arrangements are described below. For example, the fabrication of a first element over or on top of a second element in the following description may include embodiments in which the first and second elements are fabricated in direct contact, and may also include embodiments in which additional elements may be fabricated between the first and second elements such that the first and second elements are not in direct contact. Furthermore, in the present invention, reference numerals and / or letters may be repeated in the various examples.This repetition is for simplicity and clarity and does not, in itself, prescribe any relationship between the various embodiments and / or configurations discussed.

[0005] Furthermore, spatially relative terms such as "beneath," "under," "lower," "above," "upper," and the like may be used herein to conveniently describe the relationship of one element or structure to one or more other elements or structures illustrated in the figures. The spatially relative terms are intended to encompass other orientations of the device in use or operation, in addition to the orientation illustrated in the figures. The device may be oriented differently (rotated 90 degrees or in another orientation), and the spatially relative descriptors used herein may be interpreted accordingly.

[0006] In one example, the present invention provides a robust, high-transmittance membrane (pellicle) for EUV lithographic tools. As discussed above, an EUV lithographic tool may use EUV radiation to project a pattern created in a photomask onto a silicon wafer, where the pattern may be etched into the wafer. In some examples, a membrane or pellicle (e.g., a thin transparent layer, film, or foil) may be used to protect the photomask from contamination. For example, particles may fall onto the surface of the photomask. When the scanner subsequently prints the photomask pattern onto the wafer, the particles may also be printed onto the wafer, resulting in defects in the pattern. However, a properly positioned membrane can prevent particles from falling onto the photomask.

[0007] While membranes can reduce photomask contamination, they can also reduce the amount of EUV radiation reaching the photomask. For example, if the membrane film is too thick, the film can absorb much of the EUV radiation before it can reach the photomask, which can reduce the performance of the EUV lithography system. Furthermore, many common film materials are susceptible to mechanical deformation under typical processing conditions of an EUV lithography system. For example, an EUV lithography system can operate at up to 250 W in high-volume production, and under these conditions, the temperature of the membrane film can reach 686 °C, which is well above the melting point of many materials. Therefore, conventional membranes must be replaced relatively frequently.

[0008] In examples of the present invention, a robust, high-transmittance membrane is provided that is resistant to temperature- and pressure-induced deformation and transmits a high percentage (e.g., more than 82%, and in some examples, more than 90%) of the radiation to the photomask. In one example, the membrane film comprises a carbon- or silicon-based material, such as a transparent carbon nanotube layer or a transparent silicon nanowire layer, coated with a shell to ensure resistance to environmental influences. This makes the membrane film mechanically robust and also allows for better radiation transmission. In further examples, a membrane frame that holds the membrane film over the photomask can include a vent structure that creates a pressure gradient between sides of the membrane film (e.g.,between a side facing the photomask and a side facing away from the photomask). This also minimizes environmental factors that contribute to deformation of the membrane film.

[0009] Other elements may be used for the membrane disclosed herein. Some of the elements described below may also be replaced with other examples or may be eliminated. While some examples described below discuss steps performed in a particular order, these steps may be performed in other orders without departing from the scope of the present invention.

[0010] Furthermore, the membrane and methods disclosed herein may be used in several applications, including the fabrication of fin field-effect transistors (FinFETs). Examples of the present invention may also be suitable for patterning fins of a FinFET to create a relatively small spacing between features. In further examples, spacers used in fabricating the fins of the FinFET may be processed according to examples of the present invention.

[0011] Fig. 1 is a simplified schematic representation of an exemplary lithographic tool 100 according to examples of the present invention. The lithographic tool 100 may also be referred to herein as a "scanner" operable to perform lithographic exposure processes with respective radiation sources and exposure modes.

[0012] In one example, the lithographic system 100 generally includes a high luminance light source 102, an exposure device 104, a mask stage 106, a photomask 108, a projection optics module 110, and a substrate stage 112. In some examples, the lithographic system may include other components included in Fig. 1 are not shown. In further examples, the high luminance light source 102, the exposure device 104, the mask stage 106, the photomask 108, the projection optics module 110, and / or the substrate stage 112 may be omitted from the lithographic tool 100, or they may be integrated into unified components.

[0013] The high-luminance light source 102 may be configured to emit radiation with wavelengths from about 1 nm to 250 nm. In a specific example, the high-luminance light source 102 generates EUV light with a wavelength centered at about 13.5 nm, and accordingly, the high-luminance light source 102 may also be referred to as an "EUV light source" in some examples. However, it should be understood that the high-luminance light source 102 is not limited to emitting EUV light. For example, the high-luminance light source 102 may be used to perform high-intensity photon emission from an excited target material.

[0014] For example, the term "about" should be understood as within ±20% of the stated value, better within ±10% of the stated value, better within ±5% of the stated value, better within ±3% of the stated value, better within ±2% of the stated value, better within ±1% of the stated value, and better within ±0.5% of the stated value. Therefore, the stated value is an approximate value. Unless a specific value is stated, any value stated herein is an approximate value according to the definition above.

[0015] In some examples (e.g., when the lithographic tool 100 is a UV lithographic tool), the exposure device 104 includes various refractive optics components, such as a single lens or a lens system with multiple lenses (zone plates). In another example (e.g., when the lithographic tool 100 is an EUV lithographic tool), the exposure device 104 includes various mirror optics components, such as a single mirror or a mirror system with multiple mirrors. The exposure device 104 can direct light from the high-luminance light source 102 onto the mask table 106, and in particular onto the photomask 108 attached to the mask table 106. In an example where the high-luminance light source 102 generates light in the EUV wavelength range, the exposure device 104 includes mirror optics.

[0016] The mask table 106 may be configured to hold the photomask 108 in place. In some examples, the mask table 106 may include an electrostatic suction device for holding the photomask 108 in place. This is because gas molecules absorb EUV light, and the lithographic tool 100 for EUV lithographic patterning is maintained in a vacuum environment to minimize EUV intensity loss. Here, the terms "photomask," "mask," and "reticle" may be used interchangeably. In one example, the photomask 108 is a reflective mask.

[0017] In some examples, a membrane 114 may be positioned over the photomask 108, e.g., between the photomask 108 and the substrate stage 112. The membrane 114 may protect the photomask 108 from particles and may keep the particles out of focus so that the particles do not form an image (which may cause defects on a wafer during the lithography process).

[0018] The projection optics module 110 may be configured to image the pattern of the photomask 108 onto a semiconductor wafer 116 attached to the substrate stage 112. In one example, the projection optics module 110 includes refractive optics (such as for a UV lithographic tool). In another example, the projection optics module 110 includes mirror optics (such as for an EUV lithographic tool). The light directed by the photomask 108, which transmits the image of the pattern defined on the photomask 108, may be collected with the projection optics module 110. The exposure device 104 and the projection optics module 110 may be collectively referred to as an "optical module" of the lithographic tool 100.

[0019] In some examples, semiconductor wafer 116 may be a bulk semiconductor wafer. For example, semiconductor wafer 116 may be a silicon wafer. Semiconductor wafer 116 may include silicon or another elemental semiconductor material, such as germanium. In some examples, semiconductor wafer 116 may be a compound semiconductor. The compound semiconductor may be gallium arsenide, silicon carbide, indium arsenide, indium phosphide, another suitable material, or a combination thereof.

[0020] In some examples, the semiconductor wafer 116 comprises a silicon-on-insulator (SOI) substrate. The SOI substrate may be formed using a SIMOX (separation by implantation of oxygen) process, a wafer bonding process, another suitable process, or a combination thereof.

[0021] In some examples, the semiconductor wafer 116 includes an undoped substrate. However, in other examples, the semiconductor wafer 116 includes a doped substrate, such as a p-type or n-type substrate.

[0022] In some examples, the semiconductor wafer 116 includes various doped regions (not shown) depending on the design requirements of the semiconductor device structure. The doped regions may be, for example, p- and / or n-wells. In some examples, the doped regions are doped with p-type dopants. For example, the doped regions may be doped with boron or boron fluoride. In other examples, the doped regions are doped with n-type dopants. For example, the doped regions may be doped with phosphorus or arsenic. In some examples, some of the doped regions are p-doped, and other doped regions are n-doped.

[0023] In some examples, an interconnect structure may be formed over the semiconductor wafer 116. The interconnect structure may include a plurality of interlayer dielectric (ILD) layers, such as dielectric layers. The interconnect structure may also include a plurality of conductive features formed within the ILD layers. The conductive features may include conductive lines, conductive vias, and / or conductive contacts.

[0024] In some examples, various device elements are fabricated in the semiconductor wafer 116. Examples of the various device elements include transistors, e.g., metal-oxide-semiconductor field-effect transistors (MOSFETs), complementary metal-oxide-semiconductor (CMOS) transistors, bipolar transistors (BITs), 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 methods may be used to fabricate the various device elements, such as deposition, etching, implantation, photolithography, annealing, and / or other suitable methods.

[0025] The device elements may be interconnected to form integrated circuit devices through the interconnect structure above the semiconductor wafer 116. The integrated circuit devices may be logic devices, memory devices such as static random access memory (SRAM) devices, radio frequency (RF) devices, input / output (I / O) devices, system-on-a-chip (SoC) devices, image sensor devices, other suitable devices, or a combination thereof.

[0026] In some examples, semiconductor wafer 116 may be coated with a resist layer sensitive to EUV light. Various components, such as those described above, may be integrated with each other and may be operable to perform lithographic exposure processes.

[0027] Fig. 2A is a cross-sectional view of an exemplary membrane photomask structure 200 according to examples of the present invention. Fig. 2B is an isometric view of the exemplary membrane photomask structure 200 of Fig. 2A. As in the Fig. 2A and Fig. 2B, the photomask 108 may include a mask substrate 202 and a mask pattern 204 disposed over the mask substrate 202.

[0028] In some examples, the mask substrate 202 comprises a transparent substrate, such as relatively defect-free silica glass, borosilicate glass, soda-lime glass, calcium fluoride, a low thermal expansion material, an ultra-low thermal expansion material, or other suitable materials. The mask structure 204 may be disposed over the mask substrate 202, as set forth above, and may be designed according to the integrated circuit elements disposed over the semiconductor substrate (e.g., the wafer 116 of Fig. 1) are to be produced during a lithographic process. The mask structure 204 can be produced by depositing a layer of material, which is then patterned to have one or more openings through which radiation beams can pass without being absorbed, and one or more absorption regions that can completely or partially block the radiation beams.

[0029] The mask structure 204 may comprise a metal, a metal alloy, a metal silicide, a metal nitride, a metal oxide, a metal oxide nitride, or other suitable materials. Examples of materials that may be used to form the mask structure 204 include Cr, Mo x Si y , Ta x Si y , Mon, Nb x O y , Ti, Ta, Cr x N y , Mon x O y , Mon x N y , Cr x O y , Tix N y , Zr x N y , Ti x O y , Ta x N y , Ta x O y , Si x O y , Nb x N y , Zr x N y , Al x O y N z , Ta x B y O z , Ta 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 the like. The composition ratio x / y / z is not limited.

[0030] As in the Fig. 2A and Fig. 2B, the membrane 114 may be positioned over the photomask 108. In one example, the membrane 114 includes a membrane frame 206 that may be positioned over the mask substrate 202 and / or the mask structure 204. In one example, the membrane frame 206 may be made of Si, SiC, SIN, glass, a material with a low coefficient of thermal expansion (such as an Al alloy, a Ti alloy, Invar, Kovar, or the like), another suitable material, or a combination thereof. In some examples, suitable methods for forming the membrane frame 206 may include machining processes, sintering processes, photochemical etching processes, other suitable processes, or a combination thereof.

[0031] In one example, the membrane frame 206 may include a side portion 208 having an inner surface 210 and an outer surface 212, with the inner surface 210 and the outer surface 212 aligned on opposite sides of the side portion 208. The membrane frame 206 may further include a bottom or base 214 connecting the inner surface 210 and the outer surface 212.

[0032] As in the Fig. 2A and Fig. 2B, the membrane mask structure 200 may further include a vent structure 216 formed in the side portion 208 and extending from the inner surface 210 to the outer surface 212. In some examples, the vent structure 216 may include one or more holes formed in the side portion 208 of the membrane frame 206. The holes may take any shape and may be, for example, circular, rectangular, or slot-shaped, or they may take other shapes or a combination thereof. The holes may allow airflow through a portion of the membrane mask structure 200, as will be discussed in more detail later. In some examples, the holes may include filters for minimizing passage of external particles through the vent structure 216.

[0033] In some examples where the vent structure 216 includes filters, it may be fabricated together with the membrane frame 206. In some examples, the vent structure 216 may be fabricated using a photochemical etching process, another suitable process, or a combination thereof.

[0034] In other examples where the vent structure 216 includes filters, the vent structure 216 and the membrane frame 206 may be manufactured separately, and an opening (not shown) may be created in the side portion 208 of the membrane frame 206. In some examples, the vent structure 216 may then be placed into the opening in the side portion 208 of the membrane frame 206. The vent structure 216 may then be bonded to the membrane frame 206 using, for example, a brazing process, a direct diffusion bonding process, a eutectic bonding process, another suitable process, or a combination thereof.

[0035] In some examples, the vent structure 216 may prevent the membrane film from tearing during the EUV lithographic process, as will be explained in more detail later.

[0036] As also in the Fig. 2A and Fig. 2B, the membrane mask structure 200 may further include a membrane frame adhesive 218 disposed between the membrane frame 206 and the mask substrate 202.

[0037] In some examples, the membrane frame adhesive 218 may be made from a crosslinking adhesive, a thermoplastic elastomer adhesive, a polystyrene adhesive, an acrylic adhesive, a silicon-based adhesive, an epoxy adhesive, or a combination thereof.

[0038] In some examples, a surface treatment may be performed on the membrane frame 206 to improve the adhesion of the membrane frame 206 to the membrane frame adhesive 218. In some examples, the surface treatment may include an oxygen plasma treatment, another suitable treatment, or a combination thereof. However, in other examples, no surface treatment is performed on the membrane frame 206.

[0039] The membrane mask structure 200 may further include a membrane film adhesive 220 disposed over the membrane frame 206. In some examples, the membrane film adhesive 220 may be made from a thermoplastic elastomer adhesive, a polystyrene adhesive, an acrylic adhesive, a silicon-based adhesive, an epoxy adhesive, another suitable adhesive, or a combination thereof. In some examples, the membrane film adhesive 220 may be made from a different material than the material forming the membrane frame adhesive 218.

[0040] As also in the Fig. 2A and Fig. 2B, the membrane mask structure 200 may further include a membrane film 222 disposed over the membrane frame 206 and the membrane film adhesive 220. As shown, the membrane film adhesive 220 may be disposed between the membrane film 222 and the membrane frame 206.

[0041] In some examples, the membrane film 222 may include a bezel 224 disposed over the membrane film adhesive 220 and a top film portion 226 disposed over the bezel 224. In some examples, the bezel 224 may be made of Si. In other examples, the bezel 224 may be made of boron carbide, C, graphene, carbon nanotubes, SiC, SIN, SiO 2, 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 allotropic modification of one of these materials, or a combination thereof. The bezel 224 can mechanically support the upper foil portion 226 around its periphery. The bezel 224 can, in turn, be mechanically supported by the membrane frame 206 when the membrane mask structure 200 is fully assembled. That is, the membrane frame 206 can mechanically support the bezel 224 and the upper foil portion 226 of the membrane foil 222 on the photomask 108.

[0042] In one example, the vent structure 216 of the membrane frame 206 may be manufactured such that at least one side part 208 of the membrane frame 206 has a hole made in an upper part of the side part 208 (e.g., near the bezel 224) and another hole made in a lower part of the side part 208 (e.g., near the mask structure 204).

[0043] In some examples, the upper film portion 226 may be made from a transparent carbon-based layer or a transparent silicon-based layer, such as a carbon nanotube layer or a silicon nanowire layer.

[0044] Fig. 2C shows an exemplary upper film portion 226 of the membrane film 222 of the Fig. 2A and Fig. 2B. In the Fig. 2C, the upper film portion 226 comprises a carbon nanotube layer. In this example, the network of carbon nanotubes forming the carbon nanotube layer can have a feature density of 0.2 to 1, depending on the desired proportion of radiation to be transmitted through the membrane 114. For example, carbon nanotube layers have been demonstrated to achieve visible light transmittance of up to approximately 90%. Typically, a carbon nanotube thickness of 1 nm should translate into radiation absorption in the EUV wavelength range of approximately 0.5% to 1%. The exact feature density can be selected to maximize the transmittance for EUV radiation while minimizing the passage of particles through the upper film portion 226.For example, a lower feature density may allow greater transmission of EUV radiation, but the lower feature density may also allow particles to fall through to the photomask 108. The carbon nanotube layer may be fabricated using a roll-to-roll process, another suitable process, or a combination thereof.

[0045] In some examples, the carbon-based layer or the silicon-based layer may also be coated with a protective covering. For example, Fig. 2D a sectional view of an exemplary carbon nanotube 230 of the network of carbon nanotubes of Fig. 2C. As shown, the carbon nanotube 230 is coated with a protective sheath 232. The protective sheath 232 may comprise, for example, Ru, Mo, Zr, B, Nb, MoSi, SiN, SiO, another suitable material, or a combination thereof. The protective sheath 232 may have a thickness of 0.1 to 10 nm. The material and thickness for the protective sheath 232 may be selected to provide high transmittance for EUV radiation, to dissipate heat from the upper foil portion 226, and to minimize dissipation with the layer material (e.g., carbon or silicon). In one example, the protective sheath 232 may be deposited onto the network of carbon nanotubes by atomic layer deposition, physical vapor deposition, chemical vapor deposition, wet chemical plating, another suitable method, or a combination thereof.

[0046] In some examples, the enclosure 224 and / or the upper foil portion 226 may each include multiple layers. In some examples, the membrane foil 222 may be fabricated using a substrate-back photolithography / etching process, another suitable process, or a combination thereof.

[0047] In some examples, the material for the bezel 224 is the same as the material for the top foil portion 226. However, in other examples, the material for the bezel 224 is different from the material for the top foil portion 226. For example, the bezel 224 may be made of silicon, while the top foil portion 226 comprises a carbon nanotube layer. In some examples, the thickness of the top foil portion 226 may be 10 nm to 100 nm. In certain examples, the thickness of the top foil portion 226 may be 20 nm to 50 nm. These ranges have been found to provide sufficient robustness to the top foil portion 226 while also enabling high EUV transmittance. Typically, the thicker the top foil portion 226, the more robust it is, but if it is too thick, the percentage of EUV transmittance may decrease.Therefore, the specified areas represent a middle ground between these two objectives.

[0048] In some examples, the membrane frame adhesive 218 and / or the membrane film adhesive 220 may include heat-dissipating fillers. The heat-dissipating fillers may be, for example, aluminum nitride, boron nitride, aluminum oxide, magnesium oxide, silicon oxide, graphite, metal powder, ceramic powder, another suitable material, or a combination thereof. In some cases, the EUV lithographic process may utilize a high-energy light beam that penetrates the membrane film 222, increasing its temperature. The heat-dissipating fillers may assist in dissipating heat from the membrane film 222 via the membrane film adhesive 220 to the membrane frame 206, to the membrane frame adhesive 218, to the mask 108, and to the EUV lithographic device. This allows the temperature of the membrane film 222 to be lowered during EUV lithographic processing, thereby reducing the risk of the membrane film 222 tearing.

[0049] As in Fig. As shown in Figure 2A, the membrane 114 and the mask 108 may form an enclosed internal volume 228 enclosed by the membrane 114 and the mask 108. The membrane 114 and the mask 108 may separate the internal volume 228 from an external environment 230. The vent structure 216 may extend from the internal volume 228 to the external environment 230.

[0050] In some examples, the EUV lithographic process may be performed at an extremely high vacuum. Under these conditions, a membrane mask structure that is not sufficiently vented could rupture due to the pressure gradient between the internal volume 228 (e.g., the side of the membrane 114 facing the mask 108) and the external environment 230 (e.g., the side of the membrane 114 facing away from the mask 108). The membrane mask structure 200 of the Fig. 2A and Fig. 2B is less susceptible to cracking because the vent structure 216 can keep the pressure in the internal volume 228 in balance with the pressure in the external environment 230 during the EUV lithographic process.

[0051] In some examples, the membrane frame 206 includes the side panels 208, and the membrane mask structure 200 includes at least one vent structure 216 disposed in the side panels 208. As in Fig. 2B, in some examples, the membrane frame 206 may include four side panels 208, and accordingly, the membrane mask structure 200 may include at least four corresponding vent structures 216. In some examples, the four vent structures 216 may be arranged accordingly in the four side panels 208. However, numerous variations and / or modifications to the Fig. 2B. In some examples, the membrane mask structure 200 may include additional vent structures 216. In some examples, two or more vent structures 216 may be fabricated in a single side panel 208. In other examples, some of the side panels 208 may not include a vent structure 216. In further examples, a vent structure 216 may occupy the entire area of ​​the side panel 208.

[0052] It should be well understood that Fig. 1 shows only a simplified form of a lithographic system 100. In some examples, the lithographic system 100 may include additional components not shown, such as additional optical components, a plasma source, and other components.

[0053] Fig. 3 is a flowchart illustrating a method 300 for assembling a membrane for a lithographic process according to an example of the present invention. The method 300 may be used, for example, to assemble the membranes shown in the Fig. 1, Fig. 2A and Fig. 2B. The method 300 may be performed with one or more different machines controlled by a controller or processor.

[0054] The method 300 begins with a step 302. In a step 304, a transparent carbon-based or silicon-based layer may be formed on a template substrate. The template substrate may comprise, for example, polyvinyl alcohol (PVA), polystyrene (PS), polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), or a chemical vapor deposition poly(p-xylylene) polymer (e.g., parylene C). In one example where the layer is a carbon-based layer, the carbon-based layer is a carbon nanotube layer. In another example, the carbon nanotube layer has a nanotube network structure density of 0.2 to 1. In another example where the layer is a silicon-based layer, the silicon-based layer is a silicon nanowire layer.In one example, the carbon-based or silicon-based layer may be formed using a roll-to-roll process in a plasma environment, such as a plasma reaction chamber (in which the reacting gas is, for example, C). x H y , H 2 , Ar, O 2 , another suitable gas or a combination thereof).

[0055] In a step 306, the transparent carbon-based or silicon-based layer may be transferred to a bezel, and the stencil substrate may be removed to free-stand the carbon-based or silicon-based layer. In one example, a dry transfer process may be used to transfer the carbon-based or silicon-based layer from the stencil substrate to the bezel. In one example, the bezel is made of silicon. The bezel may have a rectangular shape, as shown in Fig. 2B is shown.

[0056] In a step 308, the transparent carbon-based or silicon-based layer can be coated with a protective covering to ensure environmental resistance of the carbon-based or silicon-based layer. In one example, the protective covering can comprise Ru, Mo, Zr, B, Nb, MoSi, SiN, SiO, another suitable material, or a combination thereof. The protective covering can have a thickness of 0.1 to 10 nm.

[0057] In a step 310, the enclosure and the carbon-based or silicon-based layer may be attached to a membrane frame having a ventilation structure. The membrane frame may have the same shape as the enclosure (e.g., rectangular), as shown in the Fig. 2A and Fig. 2B. In one example, the membrane frame may be made of Si, SiC, SIN, glass, a material with a low coefficient of thermal expansion (such as an Al alloy, a Ti alloy, Invar, Kovar, or the like), another suitable material, or a combination thereof. In another example, the membrane frame may have a vent structure, such as that shown in the Fig. 2A and Fig. 2B. That is, the ventilation structure may have holes that are circular, rectangular, or slot-shaped, or other suitable shapes, or a combination thereof.

[0058] In a step 312 the method can be terminated.

[0059] Fig. 4 shows a flow diagram of a method 400 for manufacturing a semiconductor device according to at least one embodiment of the present invention. At least some steps of the method 400 may be performed by means of a control device of an EUV lithographic system, such as the one shown in Fig. 1 shown lithographic system 100.

[0060] While method 400 is illustrated and described below as a series of steps or events, it should be understood that the illustrated order of these steps or events should not be construed in a limiting sense. For example, some steps may occur in different orders and / or concurrently with other steps or events than those illustrated and / or described herein. Furthermore, not all of the steps illustrated herein need implement one or more aspects or embodiments of the description, and one or more of the steps described herein may be performed in one or more separate steps and / or phases.

[0061] The method 400 begins with a step 402. In a step 404, an EUV light source may be activated to pattern a resist layer on a substrate (where the substrate may be a semiconductor wafer). The EUV light source may, for example, be part of a lithographic system, such as the one shown in Fig. 1 and discussed above. The EUV light source can generate light at EUV wavelengths (possibly by sputtering droplets of a metal into a highly ionized plasma).

[0062] In a step 406, light emitted by the EUV light source may be directed onto a photomask. The photomask may have a pattern etched into its surface, which pattern is to be printed onto the resist layer on the substrate.

[0063] In a step 408, falling particles may be trapped on a membrane positioned over the photomask to keep the photomask clear of the falling particles while the light is directed onto the photomask. In one example, the membrane comprises a transparent carbon-based or silicon-based layer coated with a protective covering that dissipates heat from the layer. The membrane may also comprise a frame supporting the layer, wherein the frame has at least one hole to allow airflow through a portion of the membrane. The membrane may, for example, be in the Fig. 2A to 2D. The membrane can be positioned to prevent particles from falling onto and contaminating the photomask.

[0064] In a step 410, the light passing through the membrane and photomask can be collected with a projection optics module and focused onto the resist layer to pattern it. For example, exposing the resist layer can result in pattern elements being printed in the resist at a desired pitch.

[0065] In one embodiment, blocks 404 to 410 may be continuously repeated during operation of the EUV light source (e.g., for multiple layers of the substrate). In a block 412, the method 400 may be terminated.

[0066] It should be noted that methods 300 and 400 may be expanded to include additional steps or modified to include additional steps beyond those discussed above. Furthermore, steps, blocks, functions, or operations of the above-described method 300 or 400 may be combined, separated, and / or performed in a different order than that described above without departing from the examples of the present invention.

[0067] Thus, examples of the present invention provide a robust, high-transmittance membrane that is resistant to temperature- and pressure-induced deformation and transmits a high percentage (e.g., greater than 82%, and in some examples, greater than 90%) of the radiation to the photomask. The membrane of the present invention may be particularly suitable for use in UV lithographic equipment, and in particular, in EUV lithographic equipment.

[0068] In one example, the present invention provides a membrane comprising a foil and a frame supporting the foil. The foil may be made from a transparent carbon-based layer and / or a transparent silicon-based layer. The transparent carbon-based layer and / or the transparent silicon-based layer may be further coated with a protective covering. The frame may have at least one hole to allow airflow through a portion of the membrane.

[0069] In another example, an apparatus comprises an EUV (extreme ultraviolet) exposure source, an exposure device, a photomask, and a membrane. The EUV exposure source is configured to generate an EUV exposure beam for patterning a resist layer on a substrate. The exposure device is configured to direct the EUV exposure beam onto a photomask. The photomask has a structure intended to pattern the resist layer. The membrane comprises a film and a frame supporting the film. The film can be made of a transparent carbon-based layer and / or a transparent silicon-based layer. The transparent carbon-based layer and / or the transparent silicon-based layer can further be coated with a protective covering.The frame may have at least one hole to allow air flow through part of the membrane.

[0070] In another example, a method includes activating an EUV light source to pattern a resist layer on a substrate. The light emitted by the EUV light source is directed onto a photomask having a membrane. The membrane includes a film and a frame supporting the film. The film may be made from a transparent carbon-based layer and / or a transparent silicon-based layer. The transparent carbon-based layer and / or the transparent silicon-based layer may be further coated with a protective covering. The frame may have at least one hole to allow airflow through a portion of the membrane. The light passing through the membrane and the photomask is collected and directed onto the resist layer.

Claims

[1] Membrane (114) with: a film (226), wherein the film (226) comprises at least one layer selected from the group consisting of a transparent carbon-based layer and a transparent silicon-based layer, wherein the at least one layer is coated with a protective sheath (232) that dissipates heat from the film (226); and a frame (206) supporting the film (226), the frame (206) having at least one hole to allow air flow through a portion of the membrane (114); the transparent carbon-based layer comprising a network of carbon nanotubes; wherein the transparent silicon-based layer comprises a network of silicon nanowires; wherein the film (226) has a thickness of 20 nm to 50 nm and transmits more than 82% of extreme ultraviolet radiation, EUV radiation. [2] The membrane (114) of claim 1, further comprising: a bezel (224) positioned between the film (226) and the frame (206), the bezel (224) being attached to the film with a membrane film adhesive (220); and a membrane frame adhesive (218) adhering to the frame (206). [3] Membrane (114) according to claim 2, wherein the membrane film adhesive (220) and / or the membrane frame adhesive (218) comprise heat-dissipating fillers. [4] The membrane (114) of claim 2 or 3, wherein the membrane frame adhesive (218) comprises at least one of the following adhesives: a crosslinking adhesive, a thermoplastic elastomer adhesive, a polystyrene adhesive, an acrylic adhesive, a silicon-based adhesive, and an epoxy adhesive. [5] The membrane (114) of any one of claims 2 to 4, wherein the membrane film adhesive (220) comprises at least one of the following adhesives: a thermoplastic elastomer adhesive, a polystyrene adhesive, an acrylic adhesive, a silicon-based adhesive, and an epoxy adhesive. [6] Membrane (114) according to one of claims 2 to 5, wherein the enclosure (224) is made of silicon. [7] The membrane (114) of claim 1, wherein the network of carbon nanotubes has a structural density of 0.2 to 1. [8] Membrane (114) according to one of the preceding claims, wherein the frame (206) is made of at least one of the following materials: silicon, silicon carbide, silicon nitride, glass, an aluminum alloy, a titanium alloy, Invar and Kovar. [9] The membrane (114) of any preceding claim, wherein the protective sheath (232) comprises at least one of the following materials: ruthenium, molybdenum, zirconium, boron, niobium, molybdenum disilicide, silicon nitride, and silicon oxide. [10] Membrane (114) according to any one of the preceding claims, wherein the protective sheath (232) has a thickness of 0.1 nm to 10 nm. [11] Device with: an extreme ultraviolet exposure source (102), EUV exposure source, arranged to generate an EUV exposure beam for patterning a resist layer on a substrate; an exposure device (104) for directing the EUV exposure beam onto a photomask (108); the photomask (108), wherein the photomask (108) has a structure with which the resist layer is to be structured; and a membrane (114) positioned over the photomask (108), the membrane (114) comprising: a film (226), wherein the film (226) comprises at least one layer selected from the group consisting of a transparent carbon-based layer and a transparent silicon-based layer, wherein the at least one layer is coated with a protective sheath (232) that dissipates heat from the film (226), and a frame (206) supporting the film (226), the frame (206) having at least one hole to allow air flow through a portion of the membrane (114); the transparent carbon-based layer comprising a network of carbon nanotubes; wherein the transparent silicon-based layer comprises a network of silicon nanowires; wherein the film (226) has a thickness of 20 nm to 50 nm and transmits more than 82% of extreme ultraviolet radiation, EUV radiation. [12] Method (400) comprising the following steps: activating (404) an extreme ultraviolet light source (102), EUV light source, to pattern a resist layer on a substrate; Directing (406) light emitted by the EUV light source (102) onto a photomask (108); Collecting (408) falling particles on a membrane (114) positioned over the photomask (108) to keep the photomask (108) clear of the falling particles while directing the light onto the photomask (1080), the membrane (114) comprising: a film (226), wherein the film (226) comprises at least one layer selected from the group consisting of a transparent carbon-based layer and a transparent silicon-based layer, wherein the at least one layer is coated with a protective sheath (232) that dissipates heat from the film (226), and a frame (206) supporting the film (226), the frame (206) having at least one hole to allow air flow through a portion of the membrane (114); and Collecting (410) a portion of the light passing through the membrane (114) and the photomask (108) and directing the portion of the light onto the resist layer; wherein the transparent carbon-based layer comprises a network of carbon nanotubes; wherein the transparent silicon-based layer comprises a network of silicon nanowires; wherein the film (226) has a thickness of 20 nm to 50 nm and transmits more than 82% of extreme ultraviolet radiation, EUV radiation.

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