pellicle diaphragm

Abstract

A pellicle membrane for an EUV lithographic apparatus, the pellicle membrane comprising: a first membrane layer forming a first outer surface; a second membrane layer forming a second outer surface substantially parallel to the first outer surface; a dielectric layer positioned between the first outer surface and the second outer surface; and wherein the first outer surface and the second outer surface are reflective to infrared radiation, the dielectric layer has a dielectric layer thickness, the membrane has a measured membrane thickness between the first outer surface and the second outer surface, and the dielectric layer thickness and the membrane thickness are selected such that the emissivity of the pellicle membrane is greater than 0.5.

Description

Cross-reference to related applications

[0001] This application claims priority to EP application 23209991.1, filed on November 15, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0002] This invention relates to a membrane diaphragm. Particularly, but not exclusively, this invention is used with EUV lithography equipment and tools. The invention also relates to membrane diaphragm assemblies and methods for manufacturing membrane diaphragms and membrane diaphragm equipment. Background Technology

[0003] A photolithography apparatus is a machine configured to apply a desired pattern onto a substrate. Photolithography apparatus can be used, for example, to manufacture integrated circuits (ICs). It can project a pattern from a patterning apparatus (e.g., a mask) onto a radiation-sensitive material (resist) layer disposed on a substrate.

[0004] To project a pattern onto a substrate, a photolithography apparatus can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the feature that can be formed on the substrate. Compared to a photolithography apparatus that can use, for example, radiation with a wavelength of 193 nm, a photolithography apparatus using extreme ultraviolet (EUV) radiation in the range of 4 nm to 20 nm (e.g., 6.7 nm or 13.5 nm) can be used to form smaller features on the substrate.

[0005] Patterning devices (e.g., masks or stencils) can be used in photolithography equipment to impart patterns to a radiation beam. Radiation is provided through or reflected from the patterning device to form an image on a substrate. Contamination on the surface of the patterning device can lead to manufacturing defects on the substrate. A diaphragm assembly (also known as a surface film) can be provided to protect the patterning device from airborne particles and other forms of contamination.

[0006] A protective film can also be provided to protect optical components other than the patterning apparatus. The film can also be used to provide a channel for lithographic radiation between relatively sealed areas of the lithography apparatus. The film can also be used as a filter, such as a spectrally pure filter, or as part of a dynamic gas lock within the lithography apparatus.

[0007] The use of a surface film in photolithography is well-known and mature. The surface film in a photolithography apparatus is a septum (also called a surface septum diaphragm), positioned away from the patterning apparatus and, in use, outside the focal plane of the photolithography apparatus. Because the surface film is outside the focal plane, contaminant particles falling on it are outside the focal point in the photolithography apparatus. Therefore, the image of the contaminant particles is not projected onto the substrate. Without a surface film, contaminant particles falling on the patterning apparatus would be projected onto the substrate, introducing defects into the projected pattern.

[0008] The mask assembly may include a surface membrane that protects the pattern forming apparatus (e.g., a mask) from particle contamination. The surface membrane may be supported by a surface membrane frame, thereby forming a surface membrane assembly or a diaphragm assembly. The surface membrane may be attached to the frame, for example, by gluing or otherwise attaching a surface membrane border region to the frame. The frame may be permanently or releasably attached to the pattern forming apparatus.

[0009] High transmittance of the diaphragm is beneficial, for example, having a single-pass EUV transmittance (EUVT) of 90% or higher. High thermal emissivity of the diaphragm is also beneficial, for example, having an emissivity close to or equal to 1 in the infrared range. A high emissivity in the diaphragm is advantageous compared to a diaphragm with lower emissivity because diaphragms with higher emissivity can generally be used at higher operating temperatures without the risk of damaging or destabilizing the diaphragm. Mechanical stability of the diaphragm is beneficial to avoid damage to the diaphragm during manufacturing, storage, transportation, and / or use. Achieving optimal transmittance, emissivity, and mechanical stability is often challenging due to the competitive requirements and physical limitations of suitable materials.

[0010] It is desirable to provide a membrane diaphragm and / or membrane assembly with improved transmittance, emissivity and / or mechanical stability or to solve problems associated with the prior art. Summary of the Invention

[0011] According to a first aspect, a surface membrane for an EUV lithography apparatus is provided, wherein the surface membrane includes: a first membrane layer forming a first outer surface; a second membrane layer forming a second outer surface substantially parallel to the first outer surface; and a dielectric layer positioned between the first and second outer surfaces. The first and second outer surfaces are reflective to infrared radiation. The dielectric layer has a dielectric layer thickness. The membrane has a measured membrane thickness between the first and second outer surfaces. The dielectric layer thickness and the membrane thickness are selected such that the emissivity of the surface membrane is greater than 0.5.

[0012] The first and second outer surfaces may be substantially parallel to each other. The dielectric layer may be substantially parallel to the first and second outer surfaces. The dielectric layer may be arranged such that it is not adjacent to either the first or second outer surface (i.e., the dielectric layer does not form part of the outer surface of the membrane). The dielectric layer may be encapsulated within a volume contained between the first and second outer surfaces. The membrane thickness may be measured on a surface substantially perpendicular to the first and second outer surfaces. The membrane may include more than one dielectric layer and more than one first and second membrane layer.

[0013] Emissivity can be emissivity in the infrared range. Emissivity in the infrared range can be referred to as thermal emissivity. The first and second membrane layers can be highly reflective in the infrared range (e.g., >50%, >80%, >90%, >95%, >99%).

[0014] Thin layers of some materials (e.g., materials with high reflectivity in the infrared range, such as metals or metal-containing materials) have a theoretical emissivity limit of 0.5. When the dielectric material is relatively thick (e.g., 1 mm), it can have a higher emissivity of up to 1. By combining a reflective diaphragm layer with a dielectric layer between the reflective diaphragm layers, an emissivity greater than 0.5 can be achieved for the diaphragm as a whole. That is, the emissivity of the surface diaphragm is greater than the theoretical emissivity limit of the diaphragm layer alone. This is because an enhanced electric field is generated within the internal volume of the diaphragm.

[0015] High emissivity (e.g., greater than 0.5) is generally desirable for diaphragms in EUV lithography equipment because high emissivity diaphragms are more durable, withstand less backwashing, and have a longer lifespan.

[0016] The first type of membrane diaphragm can be called an emissive membrane diaphragm or a high-emissivity membrane diaphragm.

[0017] The dielectric layer thickness can be less than 10 nm, and optionally on the order of 1 nm or less.

[0018] Thick dielectric materials may be unsuitable for use as surface films in EUV lithography equipment because they have very low EUV transmittance. Providing a thin dielectric layer results in a surface film with sufficient EUV transmittance and an emissivity greater than 0.5 for EUV lithography equipment. The dielectric layer thickness can additionally or alternatively be selected to be substantially smaller than the film thickness (e.g., at least an order of magnitude smaller than the film thickness).

[0019] The membrane thickness can be less than 100 nm. Optionally, the membrane thickness can be on the order of 10 nm or less.

[0020] Some materials (e.g., but not limited to metals and metal-containing materials) exhibit particularly high reflectivity in the infrared range at thicknesses below 100 nm. High infrared reflectivity can be achieved at both the first and second outer surfaces by having a diaphragm thickness of less than 100 nm. Furthermore, diaphragm thicknesses of less than 100 nm are particularly suitable for EUV applications due to their higher EUV transmittance.

[0021] The first and second diaphragm layers may include metal or metal-containing materials.

[0022] As discussed above, metals and metal-containing materials with layer thicknesses of less than 100 nm exhibit high infrared reflectivity. Therefore, by including metals or metal-containing materials in the first and second membrane layers, infrared reflectivity of the first and second outer surfaces is achieved.

[0023] The diaphragm layer may be referred to as a metallization layer or a metal layer. The diaphragm layer may include ruthenium. Preferably, the ruthenium diaphragm layer may have a total thickness of 4.5 nm. Such a thickness provides beneficial optical and thermal properties, such as increased EUV transmittance at 13.5 nm. The metallization layer may additionally or alternatively include platinum, or molybdenum, or any other material that reflects infrared radiation and is capable of EUV transmission. The metallization layer may have a diaphragm layer thickness configured to provide minimum EUV reflectance and maximum EUV transmittance.

[0024] The dielectric layer can include two-dimensional materials.

[0025] Two-dimensional materials can include graphene. Graphene can be monolayer graphene. Alternatively, graphene can have more than one layer, such as bilayer graphene, few-layer graphene (e.g., up to 5 layers), or multilayer graphene (e.g., up to 10 layers).

[0026] Advantageously, graphene minimizes the backwetting effect that thin membrane layers typically experience, especially in the high-temperature environments such as those found in photolithography equipment. Graphene also provides significant reinforcing properties to the membrane.

[0027] Two-dimensional materials can include transition metal chalcogenides. Transition metal chalcogenides can be monolayer transition metal chalcogenides. Two-dimensional transition metal chalcogenides (TMDs) can include MoSi, MoSe, WSi, or WSe.

[0028] The dielectric layer may include multiple one-dimensional materials. For example, these multiple one-dimensional materials may be carbon nanotubes.

[0029] In other words, the dielectric layer may include two-dimensional materials (such as graphene or transition metal chalcogenides (TMD)) or layers of multiple one-dimensional materials (such as an arrangement of carbon nanotubes).

[0030] The surface membrane diaphragm may further include one or more additional membrane layers and one or more additional dielectric layers positioned between the first outer surface and the second outer surface. The additional membrane layers and additional dielectric layers may be arranged such that the surface membrane diaphragm has N+1 membrane layers and N dielectric layers. Each dielectric layer may be encapsulated between adjacent membrane layers. Encapsulation between can be interpreted as being directly positioned between them, for example, each surface of the dielectric layer is adjacent to the surface of an adjacent membrane layer.

[0031] The surface membrane can have N=4 dielectric layers. A surface membrane with 4 layers of dielectric material (e.g., monolayer graphene) can provide a significantly increased emissivity.

[0032] The surface membrane / diaphragm can have N > 4 dielectric layers. For example, the surface membrane / diaphragm can have 10 dielectric layers.

[0033] According to a second aspect, a composite membrane is provided, the composite membrane comprising the membrane of the first aspect and one or more additional layers. The one or more additional membrane layers may include a core layer. The core layer may include silicon. The one or more additional membrane layers may include one or more capping layers disposed between the core layer and the membrane. Additionally or alternatively, the one or more additional membrane layers may include one or more capping layers disposed on the surface of the core layer remote from the membrane.

[0034] In other words, the emitter membrane of the first aspect can be used as part of a larger composite membrane with additional layers. For example, the additional layers can be used as reinforcing or protective layers to increase the overall strength of the membrane and / or extend the overall lifespan of the composite membrane. In the case of graphene, because graphene provides significant strength benefits, a reinforcing layer may not be necessary.

[0035] Additional layers can be provided to improve the overall thermal or optical behavior of the composite membrane. These additional membrane layers can advantageously include materials with high EUV transmittance.

[0036] An additional coating layer can be disposed between the outer surfaces of the first and second outer surfaces of the emitter coating diaphragm. Therefore, the first and second outer surfaces can be encapsulated within other layers and become the intermediate outer surface within the composite coating diaphragm.

[0037] The core layer may include, for example, silicon or silicon nitride. The capping layer may include, for example, an oxide (e.g., native surface oxide) or a plasma etching retardant material. The composite membrane may include multiple capping layers, each with a different composition, or multiple capping layers may share the same composition.

[0038] The composite membrane diaphragm may also include one or more adhesive layers between any adjacent layers of the composite membrane diaphragm. The adhesive layers can promote adhesion between adjacent layers.

[0039] In one example, the composite membrane may include the following layers in sequence: an emissive membrane, an adhesive layer, a first plasma etch retardant capping layer, a core layer, a second plasma etch retardant layer, and a native oxide layer.

[0040] In this way, the emission membrane diaphragm can be incorporated into an already used composite membrane diaphragm, thereby improving the already used membrane.

[0041] According to a third aspect, a composite membrane is provided, the composite membrane comprising the membrane of the first aspect and one or more additional layers. The one or more additional membrane layers may include a first capping layer adjacent to a first outer surface of the membrane and a second capping layer adjacent to a second outer surface of the membrane.

[0042] The capping layer may have the same properties as one or more capping layers and / or additional layers of the previous aspect. In this aspect, the emitting surface membrane diaphragm of the first aspect forms the core layer.

[0043] According to a fourth aspect, a composite membrane diaphragm is provided, the composite membrane diaphragm comprising any of the aforementioned membrane diaphragms or composite membrane diaphragms, and further comprising a frame.

[0044] The border may include silicon. The border may be disposed at the edge of the membrane or diaphragm.

[0045] According to a fifth aspect, a membrane assembly is provided, the membrane assembly comprising a membrane diaphragm or composite membrane diaphragm of any of the foregoing aspects and a frame, the membrane diaphragm or composite membrane diaphragm being supported by the frame.

[0046] According to a sixth aspect, a pattern forming apparatus assembly is provided, the pattern forming apparatus assembly including the aforementioned film assembly, the film assembly being mounted on a pattern forming apparatus for a photolithography apparatus.

[0047] A pattern forming apparatus can be referred to as a mask. Components of a pattern forming apparatus can also be referred to as a surface-forming mask.

[0048] Alternatively, the aforementioned surface diaphragm, composite surface diaphragm, or surface diaphragm assembly can be used in other areas of the lithography apparatus, for example, as part of a dynamic gas lock.

[0049] According to a seventh aspect, a method for manufacturing a surface membrane diaphragm for an EUV lithography apparatus is provided. The method includes: forming a first stack by providing a dielectric layer on a first support structure; forming a second stack by providing a first membrane layer on a second support structure; positioning the first stack on the second stack such that the dielectric layer is adjacent to the first membrane layer; removing the first support structure; providing the second membrane layer on the dielectric layer such that the dielectric layer is disposed between the first membrane layer and the second membrane layer; and removing the second support structure. The dielectric layer has a dielectric layer thickness, and the manufactured surface membrane diaphragm has a measured membrane thickness between a first outer surface formed by the first membrane layer and a second outer surface formed by the second membrane layer, the first and second outer surfaces being reflective of infrared radiation, and the dielectric layer thickness and the membrane thickness being selected such that the emissivity of the surface membrane diaphragm is greater than 0.5.

[0050] The dielectric layer can be a first dielectric layer. By positioning the first stack on top of the second stack such that the dielectric layer is directly adjacent to the first metallization layer, the dielectric layer and the first metallization layer are adhered. Additional steps can be used to ensure adhesion (e.g., adhesion between the dielectric layer and the first and / or second separator layers), such as annealing. The annealing temperature can be chosen to be a relatively low temperature, for example, a temperature below which atomic diffusion is known to play a significant role.

[0051] The dielectric layer thickness can be less than 10 nm. The dielectric layer can include two-dimensional materials or multiple one-dimensional materials. The separator thickness can be less than 100 nm. The first separator layer and / or the second separator layer can include metal or metal-containing materials.

[0052] Forming the first stack may include: providing a dielectric layer on an initial support; providing a first support structure on the dielectric layer; and removing the initial support.

[0053] The initial support can be a growth medium, such as a catalyst used in CVD, like copper. A dielectric material can be grown on the initial support. The first support structure can be a capping layer disposed on top of the dielectric material (e.g., directly adjacent to the dielectric material). The first support structure can be, for example, a PMMA layer or a naphthalene layer.

[0054] The method may further include: forming a third stack by providing a second dielectric layer on a third support structure; after providing the second separator layer and before removing the second support structure: positioning the third stack on the combined first and second stacks such that the second dielectric layer is directly adjacent to the second separator layer; removing the third support structure; and providing the third separator layer on the second dielectric layer such that the second dielectric layer is positioned between the second separator layer and the third separator layer.

[0055] The method may further include: forming an additional third layer, and repeating the steps of forming the third layer and positioning the third layer on a combined first and second layer having one or more additional membrane layers and dielectric layers, so as to form a surface membrane having N dielectric layers and N+1 membrane layers.

[0056] N can be equal to 4. A surface membrane with 4 layers of dielectric material (e.g., a single layer of graphene) can provide a significantly increased emissivity. N can be greater than 4. The fabricated surface membrane can have, for example, 10 dielectric layers.

[0057] According to an eighth aspect, a method for manufacturing a composite membrane separator is provided, the method comprising: manufacturing the membrane separator using a method according to any of the seventh aspects; and providing one or more additional membrane layers. The one or more additional membrane layers include a core layer and one or more capping layers, the core layer optionally comprising silicon, the one or more capping layers disposed between the core layer and the membrane separator, and / or disposed on a surface of the core layer remote from the membrane separator; or the one or more additional membrane layers include a first capping layer adjacent to a first outer surface of the membrane separator and a second capping layer adjacent to a second outer surface of the membrane separator.

[0058] In this way, the emission membrane can be incorporated into an existing composite membrane diaphragm, thereby improving the existing membrane while enabling the use of existing production lines.

[0059] According to a ninth aspect, a diaphragm for a dynamic gas lock in an EUV lithography apparatus is provided, wherein the diaphragm comprises: a first diaphragm layer forming a first outer surface; a second diaphragm layer forming a second outer surface substantially parallel to the first outer surface; and a dielectric layer positioned between the first and second outer surfaces. The first and second outer surfaces are reflective to infrared radiation, the dielectric layer has a dielectric layer thickness, the diaphragm has a measured diaphragm thickness between the first and second outer surfaces, and the dielectric layer thickness and the diaphragm thickness are selected such that the emissivity of the diaphragm is greater than 0.5.

[0060] Features described with respect to any aspect may be combined with features described with respect to any other aspect of the invention.

[0061] The present invention will now be described with reference to EUV lithography equipment. However, it should be understood that the present invention is not limited to EUV lithography, but can be adapted for other types of lithography. Attached Figure Description

[0062] Embodiments of the invention will now be described by way of example only with reference to the accompanying schematic drawings, in which: - Figure 1 A lithography system, including lithography equipment and a radiation source, is described; - Figure 2 The surface membrane and diaphragm were described; - Figures 3A to 3C Emissivity, EUV transmittance, and EUV reflectance of a range of materials for various layer thicknesses are shown; - Figure 4 A surface membrane with multiple dielectric layers is depicted. - Figures 5A to 5C The composite membrane diaphragm is described; - Figure 6 The method for manufacturing the membrane diaphragm is described. Detailed Implementation

[0063] Figure 1 A lithography system including a radiation source SO and a lithography apparatus LA is shown. The radiation source SO is configured to generate an EUV radiation beam B and provide the EUV radiation beam B to the lithography apparatus LA. The lithography apparatus LA includes an irradiation system IL, a support structure MT configured to support a pattern forming apparatus MA (e.g., a mask), a projection system PS, and a substrate stage WT configured to support a substrate W.

[0064] The irradiation system IL is configured to adjust the EUV radiation beam B before it is incident on the pattern forming apparatus MA. Thus, the irradiation system IL may include a faceted field mirror assembly 10 and a faceted pupil mirror assembly 11. Together, the faceted field mirror assembly 10 and the faceted pupil mirror assembly 11 provide the EUV radiation beam B with a desired cross-sectional shape and a desired intensity distribution. The irradiation system IL may include other mirrors or devices besides or replacing the faceted field mirror assembly 10 and the faceted pupil mirror assembly 11.

[0065] After this adjustment, the EUV radiation beam B interacts with the patterning device MA. This interaction produces a patterned EUV radiation beam B'.

[0066] A surface coating assembly 15 for protecting the patterning apparatus MA is depicted in the radiation path. The surface coating assembly 15 includes a surface coating diaphragm 19 and a frame 17 supporting the surface coating diaphragm 19. The surface coating diaphragm 19 may be referred to simply as a diaphragm. The surface coating diaphragm 19 comprises a thin film that is substantially transparent to EUV radiation (although the surface coating diaphragm 19 will absorb a small amount of EUV radiation). The surface coating diaphragm 19 is used to protect the patterning apparatus MA from particle contamination. The surface coating diaphragm 19 may be simply referred to as the surface coating. It should be understood that the surface coating assembly 15 can be located wherever required and can be used to protect any component of the lithography apparatus, such as one or more mirrors in the lithography apparatus.

[0067] Although efforts may be made to maintain a clean environment inside the lithography apparatus LA, particles may still be present inside the lithography apparatus LA. In the absence of the surface film 19, particles may deposit onto the patterning apparatus MA. Particles on the patterning apparatus MA may adversely affect the pattern applied to the radiation beam B, and thus affect the pattern transferred to the substrate W. The surface film 19 provides a barrier between the patterning apparatus MA and the environment within the lithography apparatus LA to prevent particle deposition on the patterning apparatus MA.

[0068] In use, the coating 19 is positioned at a distance sufficient to prevent any particles incident on the surface of the coating 19 from being within the focal plane of the radiation beam B. This spacing between the coating 19 and the pattern forming apparatus MA reduces the extent to which any particles on the surface of the coating 19 contribute a pattern to the radiation beam B. It will be understood that if particles are present in the radiation beam B but located outside the focal plane of the beam (e.g., outside the surface of the pattern forming apparatus MA), any image of the particles will not be focused on the surface of the substrate W. In some embodiments, the spacing between the coating 19 and the pattern forming apparatus MA may be, for example, between 2 mm and 3 mm (e.g., about 2.5 mm). In some embodiments, the spacing between the coating 19 and the pattern forming apparatus may be adjustable.

[0069] After generating the patterned EUV radiation beam B', the projection system PS is configured to project the patterned EUV radiation beam B' onto the substrate W. For this purpose, the projection system PS may include a plurality of mirrors 13, 14, configured to project the patterned EUV radiation beam B' onto the substrate W held by the substrate stage WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B' to form an image with features smaller than the corresponding features on the pattern forming apparatus MA. For example, a reduction factor of 4 or 8 may be applied. Although in Figure 1The projection system PS shown has only two mirrors 13 and 14, but the projection system PS may include a different number of mirrors (e.g., six or eight mirrors).

[0070] The substrate W may include a previously formed pattern. In this case, the photolithography apparatus LA aligns the image formed by the patterned EUV radiation beam B' with the pattern previously formed on the substrate W.

[0071] A relative vacuum, i.e., a small amount of gas (e.g., hydrogen) at a pressure much lower than atmospheric pressure, can be provided in the radiation source SO, the irradiation system IL, and / or the projection system PS.

[0072] The radiation source SO can be a laser-generated plasma (LPP) source, a discharge-generated plasma (DPP) source, a free-electron laser (FEL), or any other radiation source capable of generating EUV radiation.

[0073] Figure 2 A surface membrane diaphragm 200 is depicted. The surface membrane diaphragm 200 includes a first membrane layer 200A, a second membrane layer 200B, and a dielectric layer 201 encapsulated between the first and second membrane layers as a dielectric material 201. Typically, membrane layers 200A and 200B are made of materials and / or structures that reflect infrared radiation. The membrane layers may include metals, metal-containing materials, or metalloid materials (e.g., materials that exhibit metallic-like properties, particularly regarding their interaction with infrared radiation), or may be composed of metals, metal-containing materials, or metalloid materials. When a membrane layer includes a metal, it may be referred to as a metal layer or a metallized layer.

[0074] Using diaphragm 200, a reflective interface is formed by a first diaphragm layer 200A at the top surface 210 (referred to as the first outer surface 210). Similarly, a reflective interface is formed by a second diaphragm layer 200B at the bottom surface 220 (referred to as the second outer surface 220). As used herein, "top" and "bottom" are relative to... Figure 2 The term is relative to orientation, but it should be understood that the diaphragm can be oriented differently.

[0075] The behavior of the membrane diaphragm 200 will now be described with reference to specific example compositions, but it should be understood that the membrane diaphragm 200 can be implemented differently while still achieving the beneficial diaphragm properties described herein.

[0076] The dielectric layer 201 may be formed of a single layer of graphene. The first separator layer 200A and the second separator layer 200B may contain metals, such as ruthenium. The separator 200 has a separator thickness (e.g., measured approximately perpendicularly) between the first outer surface 210 and the second outer surface 220. The separator thickness is preferably less than 100 nm. Typically, bulk metals have poor emissivity because their surfaces are highly reflective, with reflectivity close to 100% at infrared wavelengths. In thin layers of metal (e.g., less than 100 nm), radiation is reflected from the metal surface but also penetrates into the metal. Therefore, when radiation is incident on the outer surface of a metal layer in free space (e.g., in air or a vacuum), a portion of the radiation will initially be reflected by the metal-air (or metal-vacuum) interface with a phase shift of 180°. However, another portion of the radiation will penetrate into the layer. The penetrating radiation will be reflected from the opposite (bottom) surface of the metal layer and travel back to the top surface, with a portion of the radiation coupled outward from the top surface of the metal layer into the air (or vacuum). However, the outwardly coupled radiation does not undergo a phase shift and therefore cancels out the initially reflected radiation due to superposition. As a result, total internal reflection of the thin metal layer is almost nonexistent (i.e., almost zero). The radiation penetrating the metal layer can be absorbed, resulting in an increased emissivity of the thin metal layer compared to a bulk metal. In any case, the theoretically maximum thermal infrared emissivity achievable for the metal layer is 0.5 (50%).

[0077] It has been recognized that by encapsulating the dielectric material layer 201 between two thin films of metal (or another reflective material), the emissivity of the entire diaphragm can be increased to above 0.5. Figure 2 The diagram illustrates some of the mechanisms that enable this high emissivity. Figure 2 Emission event 203 is shown, thereby emitting light internally within the membrane layer 200A. The origin of emission event 203 may be due to prior absorption of radiation by the membrane layer 200A, where the radiation may have already penetrated into the membrane layer, as described above. Figure 2 The emission event 203 is described as being caused by the first diaphragm layer 200A, but such an event can be similarly caused by the second diaphragm layer 200B, and the same physical mechanism will occur as detailed below.

[0078] The light emitted in emission event 203 travels to the surface 210 of the membrane 200. Some of the light is transmitted through the membrane 200, while a portion is reflected back into the membrane 200 due to reflection at the outer surface 210. The reflected portion travels through the dielectric layer 201 during its propagation through the membrane 200, and further absorption and subsequent further emission events 204 occur. For simplicity, in Figure 2Five further emission events 204 are depicted, but in reality, many more emission events will occur. Each emission event 203, 204 results in additional radiation propagating through the diaphragm 200 and being reflected from the top and bottom surfaces of the diaphragm 200.

[0079] Multiple reflections contribute to an enhanced (e.g., increased) electric field within the membrane 200. This enhanced electric field subsequently increases the emissivity of the dielectric layer 201. Therefore, the enhanced electric field increases the emissivity of the entire membrane 200. Specifically, the enhanced electric field increases the emissivity of the membrane 200 compared to the theoretical maximum for the constituent parts of the membrane 200 (e.g., a thin metal layer). In a specific example using monolayer graphene, the thermal emissivity of the monolayer graphene can increase to as high as 0.97 (i.e., 97%) of the theoretical maximum when the graphene is situated in an enhanced electric field. Significant increases in thermal emissivity (but below the theoretical maximum), such as 0.84 (84%), have also been observed in non-ideal cases.

[0080] Furthermore, the dielectric layer 201 has a high EUV transmittance, which is beneficial for reducing losses in EUV lithography equipment and processes. Monolayer graphene is particularly suitable for this purpose because it has an EUV transmittance of 99.8%.

[0081] The dielectric layer 201 can be formed from materials other than graphene. A range of two-dimensional materials can be used, such as transition metal chalcogenides (e.g., tungsten diselenide WSe2, tungsten disulfide WS2, molybdenum diselenide MoSe2, molybdenum disulfide MoS2, etc.). Alternatively, other low-dimensional material layers, such as carbon nanotube (CNT) layers, can be used. The dielectric material can also be doped, for example, using doped graphene. Multilayer graphene (e.g., bilayer, more than 2 layers) can also be used. Instead of the dielectric layer 201, a high-emissivity material layer can be used at the location of the dielectric layer 201. That is, the material forming the dielectric layer 201 does not need to strictly include a dielectric material, but rather shares the property of high emissivity in an enhanced electric field in order to achieve enhanced emissivity (>0.5) of the surface membrane. Therefore, the terms "dielectric layer" and "high-emissivity layer" can be used interchangeably.

[0082] Many metals are suitable for use as membrane layers 200A and 200B, such as ruthenium, molybdenum, yttrium, gold, copper, silver, or aluminum. Other materials, such as metal silicides, including but not limited to molybdenum silicide, niobium silicide, ruthenium silicide, and zirconium silicide, can also be used. Typically, membrane layers 200A and 200B should have high reflectivity to infrared radiation. Membrane layers 200A and 200B can also be selected to have high EUV transmittance, for example, greater than 90%.

[0083] It is advantageous to select the thickness of the diaphragm (e.g., the thickness between the first outer surface 210 and the second outer surface 220) and the thickness of the individual sublayers (e.g., diaphragm layers 200A, 200b and dielectric layer 201) in order to optimize thermal emissivity, EUV reflectivity and EUV transmittance. Figures 3A to 3C Emissivity, EUV reflectance (EUVR), and EUV transmittance (EUVT) of various materials that can be used in the membranes and diaphragms described herein are shown. In particular, the materials are ruthenium, molybdenum, yttrium, and graphite. It should be understood that the materials can be used in their pure form or as components of other compositions (or as materials associated with other compositions) (e.g., MoS2 includes molybdenum, and monolayer graphene shares some properties with graphite).

[0084] Figure 3A The emissivity for materials with various layer thicknesses between 0 and 100 nm is shown, and it can be seen that none exceed 0.5. Graphite achieves the highest emissivity of 0.5 at a thickness of approximately 20 nm.

[0085] Figure 3B The EUVR for the material at a wavelength of 13.5 nm is shown for various layer thicknesses. Minimizing EUVR is generally desirable to avoid dose loss due to reflection. The maximum EUVR occurs at multiples of the EUV wavelength, and the minimum EUVR occurs at multiples of the EUV wavelength. Therefore, choosing layer thicknesses that are multiples of the EUV wavelength (i.e., 6.8 nm, 13.5 nm, 20.3 nm) may be particularly advantageous. At these thicknesses, the layer effectively acts as an antireflective layer. Typically, among the materials shown, ruthenium has the highest reflectivity, while graphite and yttrium exhibit low EUVR.

[0086] Figure 3C The EUVT of the material at a wavelength of 13.5 nm is shown for various layer thicknesses. It can be seen that for all materials, the EUVT decreases with increasing layer thickness, but yttrium experiences the smallest decrease in EUVT with increasing layer thickness.

[0087] All three metrics can be considered in parallel. Figure 3A Emittance in Figure 3B EUVR and Figure 3CEUVT (EUVT) is used to optimize material selection and layer thickness. Ruthenium with a total thickness of 4 nm to 5 nm (e.g., the cumulative thickness of all 200A and 200B layers) has been found to be the optimal candidate for separator layers 200A and 200B. 4 nm to 5 nm of ruthenium provides a favorable balance of acceptable high emissivity, EUVT, and acceptable low EUVR. Furthermore, it has been found that ruthenium layers of this thickness do not exhibit significant backwetting at standard EUV lithography temperatures (e.g., on the order of several hundred degrees, such as 400°C to 700°C). Of course, other layer thicknesses and other materials, whether discussed herein or elsewhere, can be selected based on their known material properties. While in Figures 3A to 3C Not shown, but platinum could be a suitable candidate metal for the membrane layer. Other material properties can also be used to determine the suitability of a material; for example, materials with structural and / or chemical stability can be beneficial. For instance, non-oxidizing materials might be desirable.

[0088] By improving the emissivity of the diaphragm, the operating temperature of the diaphragm can be reduced. For example, if the emissivity is higher, the diaphragm can dissipate more heat and thus maintain a lower temperature. In this way, the diaphragm can withstand higher intensity EUV radiation without reaching a sufficiently high temperature that would cause significant damage. Therefore, higher power EUV radiation can be used, resulting in increased yield in the lithography process without increasing the risk of diaphragm damage. An exemplary diaphragm with an emissivity of 0.45 can have an operating temperature of 500°C when irradiated with a 400W EUV source. A diaphragm with an emissivity of 0.84, as described herein, can be used with the same 400W EUV source, but at a lower temperature of 400°C. At this lower operating temperature, the diaphragm will be damaged more slowly and therefore has a longer lifespan compared to the diaphragm with an emissivity of 0.45. Alternatively, the diaphragm can be used with a higher power EUV source, such as a source with 650W power, before the diaphragm reaches its 500°C operating temperature.

[0089] refer to Figures 3A to 3C The described membrane thickness should be understood as the overall membrane thickness (i.e., the distance between the first outer surface 210 and the second outer surface 220). The membrane thickness can be referred to as the total membrane thickness. Therefore, the membrane thickness is the combined thickness of the first membrane layer 200A and the second membrane layer 200B, plus the thickness of the dielectric layer 201. In some cases, such as due to the gaps between each layer, the total membrane thickness may be slightly greater than the precise combined thickness of each individual layer.

[0090] In one example, if the first separator layer 200A and the second separator layer 200B have a total combined thickness of 4.5 nm, and the dielectric layer 201 comprises a monolayer of graphene (with a layer thickness of approximately 0.8 nm), the total separator thickness will be close to 5.8 nm. Each of the first separator layer 200A and the second separator layer 200B may have substantially the same thickness (e.g., both have a thickness of 2.25 nm), or they may have different layer thicknesses.

[0091] Additional dielectric layers can be introduced to further improve the surface membrane. Figure 4 An example of a surface membrane 400 having multiple dielectric layers 401A to 401D is depicted. In this example, the membrane 400 still has a first outer surface 410 and a second outer surface 420, wherein the membrane thickness is defined as the distance between the two outer surfaces 410, 420. The membrane 400 includes four dielectric layers 401A to 401D and five membrane layers 400A to 400E. The properties of the dielectric layers 401A to 401D and the properties of the membrane layers 400A to 400E can be referenced above. Figure 2 and Figures 3A to 3C As stated above.

[0092] Typically, the diaphragm described herein has N dielectric layers and N+1 membrane layers, with the dielectric layers arranged between adjacent membrane layers. In all cases, two membrane layers form the outer surface, but the other membrane layers are contained within the internal volume of the diaphragm. Typically, the diaphragm will have a total diaphragm thickness T approximately equal to T = YN + X(N+1), where Y is the dielectric layer thickness and X is the membrane layer thickness. Alternatively, one or all membrane layers may have different membrane layer thicknesses, and / or one or all dielectric layers may have different dielectric layer thicknesses. In this case, the total diaphragm thickness may be equal to the sum of the thicknesses of each component layer.

[0093] exist Figure 4In the example, N=4. This arrangement has been found to be particularly advantageous for achieving a membrane with high emissivity. Other values ​​of N can be used. Table 1 below depicts the EUVT, thermal emissivity, and operating temperature for various values ​​of N in the example membrane, where the dielectric layer comprises a monolayer of graphene, and each membrane layer comprises ruthenium. The ruthenium membrane layers have layer thicknesses such that the sum of the thicknesses of all ruthenium layers equals approximately 4.5 nm. For example, with N=1, each ruthenium layer has a layer thickness of 2.25 nm, and the total membrane thickness T is approximately 4.5 nm + 1 (0.8 nm) = 5.3 nm. Alternatively, with N=4, the membrane sequentially comprises: a first membrane layer with a thickness of 1.5 nm, a first dielectric layer, a second membrane layer with a thickness of 0.5 nm, a second dielectric layer, a third membrane layer with a thickness of 0.5 nm, a third dielectric layer, a fourth membrane layer with a thickness of 0.5 nm, a fourth dielectric layer, and a fifth dielectric layer with a thickness of 1.5 nm. If the first, second, third, and fourth dielectric layers comprise monolayer graphene, then each dielectric layer will have a thickness of 0.8 nm. The resulting membrane will have a total membrane thickness of 7.7 nm.

[0094] Table 1: Optical and thermal properties of surface films and membranes with various numbers of dielectric layers including monolayer graphene: N Emission rate EUVT (%) Operating temperature (°C) 0 0.50 88.0 605 1 0.53 87.8 597 2 0.55 87.6 595 3 0.57 87.4 591 4 0.59 92.7 484 5 0.61 92.5 484 6 0.63 92 483 25 0.92 90 482

[0095] In the examples presented in Table 1, each separator can be implemented with an additional core layer. Such a core layer can be provided to provide strength. The core layer may include silicon and / or silicon nitride (SiN). It has been particularly found that a core layer is advantageous for separators with fewer dielectric layers. However, when monolayer graphene is used as the dielectric layer, the graphene can provide sufficient strength to the separator so that an additional reinforcing layer is not required (e.g., no core layer is needed). Multilayer graphene can provide even greater strength. Therefore, in some embodiments, a core layer may be provided when N < 4, and no core layer may be provided when N ≥ 4.

[0096] The membrane diaphragm can be incorporated into the membrane assembly, for example, as referenced. Figure 1 The described membrane assembly 15 may have a frame 57 supporting the membrane diaphragm. The frame 57 may include silicon. Figures 5A to 5C An exemplary membrane assembly including an emissivity membrane diaphragm as described herein is depicted.

[0097] Figure 5AA composite surface membrane 500 comprising the surface membrane 501 as described above is depicted. That is, the composite surface membrane 500 includes the surface membrane 501, which comprises at least one dielectric layer and at least two membrane layers, and the surface membrane 501 has an overall emissivity greater than 0.5. The composite surface membrane 500 also has a border 57. The border 57 takes the form of a border surrounding the edge of the surface membrane 501. Figures 5A to 5C As shown in cross-section, and thus the visible portion of the frame 57 appears to be two arms supporting the distal end of the diaphragm 501.

[0098] Figure 5B A second composite surface membrane 510 is depicted. The second composite surface membrane 510 includes the surface membrane 501 as described above. The second composite surface membrane 510 also includes cap layers 512, 513 and a core layer 511. The core layer 511 may, for example, comprise silicon. The cap layers include two plasma-resistant cap layers 512 and a native oxide layer 513. The core layer and cap layers are known in the field of surface membranes and will not be described in detail here. However, including… Figure 5B This demonstrates how the membrane 501 described herein can be incorporated into other membrane structures or membrane assemblies (e.g., known membrane assembly structures) to improve their thermal and / or structural properties. The second composite membrane 510 also has a border 57.

[0099] Figure 5C A third composite surface membrane 520 is depicted. The third composite surface membrane 520 includes a surface membrane 501 as described above, wherein a capping layer 522 is disposed at a first outer surface and a second outer surface 521 of the surface membrane 501. Thus, the “outer surface” 521 of the surface membrane 501 now forms an intermediate outer surface within the overall volume of the third composite surface membrane 520. However, the outer surface 521 still exhibits high reflectivity (e.g., due to the optical properties of the interface between the surface membrane 501 and the capping layer 522), and therefore still experiences the desired enhanced electric field within the surface membrane 501. The third composite surface membrane 520 also has a border 57.

[0100] Each composite membrane diaphragm 500, 510, 520 includes a membrane diaphragm according to the invention and one or more additional layers. The additional layer may be a cap layer, a core layer, a border, etc. Any other additional layer may also be introduced, for example, to improve the thermal, optical, chemical, mechanical, or any other properties of the composite membrane and membrane assembly.

[0101] Attached to or alternative to frame 57, the surface membrane 500 may be supported by a frame, for example, at the edge of the surface membrane 500. The frame may include silicon. The surface membrane 500 including the frame may be referred to as a surface membrane assembly. The frame may be attached (e.g., glued) to the composite surface membrane 500 at the location of frame 57. Alternatively, the frame may be attached without using a frame. For example, as described above, the use of graphene in the surface membrane 500 imparts significant strength to the membrane, and therefore additional strength from the frame may not be required.

[0102] Figure 6 A method for fabricating a surface-film separator as described herein is depicted. The example method is described with reference to a surface-film separator comprising a graphene dielectric layer. However, this teaching can be extended to other types of dielectric layers.

[0103] In the first step 601, a graphene layer 601a is provided on an initial support 601b. The initial support 601b can be, for example, copper or another catalyst suitable for chemical vapor deposition of graphene. The graphene layer 601a (or other dielectric layer) can be deposited in different ways, in which case another initial support can be suitable.

[0104] In the second step 602, a first support structure 602a may be provided on the graphene layer 601a. ​​The first support structure 602a may be a protective capping layer. The first support structure 602a may be formed of a PMMA layer or a naphthalene layer.

[0105] In the third step 603, the initial support 601b is removed, for example by etching or mechanical removal. This leaves the graphene 601a on the first support layer 602a. The combination of graphene and the first support layer can be referred to as the first stack.

[0106] The first two or three steps 601, 602, 603 can be performed in isolation from the remaining steps, so that the supply of the first stack can be used for the following method steps.

[0107] In the fourth step 604, the second stack is formed by providing a first diaphragm layer 604a on the second support structure 604b. For example, and as described above, the first diaphragm layer 604a may be a metal layer or other reflective material layer.

[0108] In the fifth step 605, the first stack is positioned on the second stack, so that the graphene layer 601a is deposited on the first membrane layer 604a.

[0109] In the sixth step 606, the first support structure 601a is removed. In this way, the surface of the graphene layer 601a that was previously covered by the first support structure 601a is uncovered.

[0110] In the seventh step 607, a second separator layer 607a is provided on the uncovered surface of the graphene layer 601a. ​​That is, the second separator layer 607a is provided adjacent to the graphene layer 601a. ​​The graphene layer 601a is now positioned between the first separator layer 604a and the second separator layer 607a (encapsulated by the first separator layer 604a and the second separator layer 607a).

[0111] Alternatively, additional graphene layers and additional membrane layers may be added, for example by introducing an additional stack including a dielectric layer and an additional support structure, and then removing the additional support structure.

[0112] In the final step 608, the second support structure 604b is removed. Therefore, the manufactured diaphragm comprises (at least) two diaphragm layers 604a, 607a and one (or more) dielectric layers 604a between each pair of adjacent diaphragm layers. Each of the two outer diaphragm layers has an uncovered surface, thus forming an outer surface.

[0113] In this way, a surface membrane with N dielectric layers and N+1 separator layers can be manufactured. This manufacturing method is particularly robust when using graphene, for example, due to its mechanical strength. Therefore, the risk of damaging the surface membrane at each stage is significantly reduced.

[0114] In any of the steps described above where one layer is deposited onto another, an annealing (e.g., heating) step can be added to improve adhesion between the layers. Graphene prevents or delays the initiation of thermal backwetting of any adjacent layers (especially metallized layers) and provides strong adhesive properties, thus reducing the need for other methods to promote adhesion.

[0115] This article has referenced “high” emissivity, high EUV transmittance (EUVT), and high or low EUV reflectance (EUVR). For emissivity, high can be considered greater than 50%, 80%, or 90%. For EUV transmittance, high can be considered greater than 90%, 95%, or 99%. High EUV reflectance can be considered greater than 4%. Therefore, low EUV reflectance can be considered greater than 4%. These values ​​are provided as examples, and values ​​considered high or low in a particular case may depend on the expected yield of the device and / or comparison with existing technologies.

[0116] The diaphragm described in this article can be used in applications beyond the surface film. For example, the diaphragm can be used as part of a dynamic gas lock. Dynamic gas locks are particularly beneficial in EUV lithography equipment.

[0117] The above describes composite membrane diaphragms. The term "composite" is intended to indicate that the membrane diaphragm includes additional layers. In this context, the term "composite" does not mean that the materials used must be composite materials. For example, one or more additional layers may include a single material, such as a metal.

[0118] While this article provides specific references to the use of lithography equipment in IC manufacturing, it will be understood that the lithography equipment described herein can have other applications. Other potential applications include manufacturing integrated optical systems, guiding and detecting patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin-film magnetic heads, etc.

[0119] Although embodiments of the invention may be specifically referred to herein in the context of lithography equipment, embodiments of the invention can be used in other equipment. Embodiments of the invention can form part of mask inspection equipment, metrology equipment, or any equipment that measures or processes objects such as wafers (or other substrates) or masks (or other patterning apparatus). These devices are generally referred to as lithography tools. Such lithography tools can use vacuum conditions or ambient (non-vacuum) conditions.

[0120] Although the foregoing may have specifically referenced the use of embodiments of the invention in the context of optical lithography, it should be understood that, where the context permits, the invention is not limited to optical lithography and can be used in other applications such as imprint lithography.

[0121] Although specific embodiments of the invention have been described above, it will be understood that the invention can be practiced in ways other than those described. The above description is intended to be illustrative and not restrictive. Therefore, it will be apparent to those skilled in the art that modifications can be made to the described invention without departing from the scope of the claims set forth below.

Claims

1. A surface film diaphragm for EUV lithography equipment, wherein, The membrane diaphragm includes: A first diaphragm layer, wherein the first diaphragm layer forms a first outer surface; A second membrane layer is formed on a second outer surface that is substantially parallel to the first outer surface; A dielectric layer, wherein the dielectric layer is positioned between the first outer surface and the second outer surface; Wherein, the first outer surface and the second outer surface are reflective to infrared radiation, the dielectric layer has a dielectric layer thickness, the diaphragm has a diaphragm thickness measured between the first outer surface and the second outer surface, and the dielectric layer thickness and the diaphragm thickness are selected such that the emissivity of the surface membrane diaphragm is greater than 0.

5.

2. The membrane diaphragm according to claim 1, wherein, The dielectric layer thickness is less than 10 nm, and optionally on the order of 1 nm or less than 1 nm.

3. The membrane diaphragm according to claim 1 or 2, wherein, The thickness of the diaphragm is less than 100 nm.

4. The membrane diaphragm according to any one of the preceding claims, wherein, The first membrane layer and the second membrane layer comprise metal or metallic materials.

5. The membrane diaphragm according to any one of the preceding claims, wherein, The dielectric layer comprises a two-dimensional material.

6. The membrane diaphragm according to claim 5, wherein, The two-dimensional material includes graphene, and optionally, the graphene is monolayer graphene.

7. The membrane diaphragm according to claim 5, wherein, The two-dimensional material includes a transition metal chalcogenide, and optionally, the transition metal chalcogenide is a monolayer transition metal chalcogenide.

8. The membrane diaphragm according to any one of claims 1 to 4, wherein, The dielectric layer comprises multiple one-dimensional materials.

9. The membrane diaphragm according to any one of the preceding claims, further comprising one or more additional membrane layers and one or more additional dielectric layers positioned between the first outer surface and the second outer surface, said one or more additional membrane layers and said one or more additional dielectric layers being arranged such that the membrane diaphragm has N+1 membrane layers and N dielectric layers, and wherein, Each dielectric layer is encapsulated between adjacent separator layers.

10. The membrane diaphragm according to claim 9, wherein, N=4。 11. The membrane diaphragm according to claim 9, wherein, N>4。 12. The membrane diaphragm according to any one of the preceding claims, wherein, The diaphragm layer includes ruthenium.

13. A composite membrane separator, comprising a membrane separator according to any one of the preceding claims and one or more additional layers, wherein, The one or more additional surface coating layers include: A core layer, wherein the core layer optionally comprises silicon; One or more capping layers are disposed between the core layer and the outer membrane diaphragm, and / or disposed on the surface of the core layer away from the outer membrane diaphragm.

14. A composite membrane diaphragm, comprising a membrane diaphragm according to any one of the preceding claims and one or more additional layers, wherein the one or more additional membrane layers comprise a first cap layer adjacent to a first outer surface of the membrane diaphragm and a second cap layer adjacent to a second outer surface of the membrane diaphragm.

15. A composite membrane diaphragm, comprising the membrane diaphragm or composite membrane diaphragm according to any one of the preceding claims, and further comprising a frame.

16. A membrane assembly comprising a membrane diaphragm or composite membrane diaphragm according to any one of the preceding claims and a frame, wherein the membrane diaphragm or composite membrane diaphragm is supported by the frame.

17. A pattern forming apparatus assembly comprising the film assembly according to claim 16, the film assembly being mounted on a pattern forming apparatus for a photolithography apparatus.

18. A method for manufacturing a diaphragm for an EUV lithography apparatus, the method comprising: The first stack is formed by providing a dielectric layer on the first support structure; The second stack is formed by providing a first diaphragm layer on the second support structure; Position the first stack on the second stack such that the dielectric layer is adjacent to the first separator layer; Remove the first support structure; A second separator layer is provided on the dielectric layer, such that the dielectric layer is disposed between the first separator layer and the second separator layer; as well as Remove the second support structure; The dielectric layer has a dielectric layer thickness, and the manufactured surface membrane has a membrane thickness measured between a first outer surface formed by the first membrane layer and a second outer surface formed by the second membrane layer, the first outer surface and the second outer surface being reflective to infrared radiation, and the dielectric layer thickness and the membrane thickness being selected such that the emissivity of the surface membrane is greater than 0.

5.

19. The method of claim 18, wherein: The dielectric layer is less than 10 nm thick, and optionally, the dielectric layer comprises a two-dimensional material or multiple one-dimensional materials; and / or The membrane thickness is less than 100 nm, and optionally, the first membrane layer and / or the second membrane layer comprises metal or a metal-containing material.

20. The method according to claim 18 or 19, wherein, Forming the first stack includes: The dielectric layer is provided on the initial support; The first support structure is provided on the dielectric layer; Remove the initial support member.

21. The method according to any one of claims 18 to 20, further comprising: The third stack is formed by providing a second dielectric layer on the third support structure; After the second membrane layer is provided and before the second support structure is removed: The third stack is positioned on the combined first and second stacks such that the second dielectric layer is directly adjacent to the second membrane layer. Remove the third support structure; as well as A third separator layer is provided on the second dielectric layer such that the second dielectric layer is positioned between the second separator layer and the third separator layer.

22. The method of claim 19, further comprising forming an additional third stack and repeating the steps of claim 19 to form a surface membrane having N dielectric layers and N+1 membrane layers.

23. The method according to claim 22, wherein, N=4。 24. The method according to claim 22, wherein, N＞4。 25. A method for manufacturing a composite membrane separator, the method comprising: The membrane diaphragm is manufactured using the method according to any one of claims 18 to 24; as well as One or more additional coating layers are provided, wherein the one or more additional coating layers comprise: A core layer and one or more capping layers, the core layer optionally comprising silicon, the one or more capping layers being disposed between the core layer and the surface membrane and / or disposed on the surface of the core layer away from the surface membrane; or The one or more additional surface layers include a first cap layer adjacent to the first outer surface of the surface membrane and a second cap layer adjacent to the second outer surface of the surface membrane.

26. A diaphragm for a dynamic gas lock in an EUV lithography apparatus, wherein the diaphragm comprises: A first diaphragm layer, wherein the first diaphragm layer forms a first outer surface; A second membrane layer is formed on a second outer surface that is substantially parallel to the first outer surface; A dielectric layer, wherein the dielectric layer is positioned between the first outer surface and the second outer surface; Wherein, the first outer surface and the second outer surface are reflective to infrared radiation, the dielectric layer has a dielectric layer thickness, the diaphragm has a diaphragm thickness measured between the first outer surface and the second outer surface, and the dielectric layer thickness and the diaphragm thickness are selected such that the emissivity of the diaphragm is greater than 0.5.

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