Pellicle membrane, pellicle, and method of making same
By employing a metal silicon carbon nitride core and a silicon oxide carbon nitride cover layer in the EUV lithography equipment, the balance between high strength and high transmittance of the surface film diaphragm is solved, thereby improving the stability and production efficiency of the equipment.
Patent Information
- Application Number
- CN202480043523.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-06-27
- Filing Date
- 2024-05-28
- Publication Date
- 2026-01-23
AI Technical Summary
The surface and diaphragm in existing EUV lithography equipment struggle to balance high strength and high transmittance, and are susceptible to oxidation and cracking, leading to a decline in equipment performance.
The membrane design incorporates a core of metallic silicon carbonitride and a cover layer of silicon oxide carbonitride. By adjusting the material composition and structure, mechanical strength and EUV transmittance are improved, while reducing the risk of oxidation and breakage.
It achieves higher transmittance and stability in EUV lithography equipment, reduces equipment operating temperature and breakage risk, and improves equipment lifespan and production efficiency.
Smart Images
Figure CN121399541A_ABST
Abstract
Description
[0001] Cross-references to related applications
[0002] This application claims priority to European application 23181712.3, filed on 27 June 2023, the entire contents of which are incorporated herein by reference. Technical Field
[0003] This invention relates to a diaphragm for a photolithography apparatus, a diaphragm assembly for a photolithography apparatus, a method for manufacturing the diaphragm, and the use of such a diaphragm, assembly, or method in a photolithography apparatus or method. This invention has specific, but not exclusive, applications to EUV lithography apparatus and methods. Background Technology
[0004] A photolithography apparatus is a machine configured to apply a desired pattern onto a substrate. Photolithography apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A photolithography apparatus can project a pattern from a patterning apparatus (e.g., a mask) onto a layer of radiation-sensitive material (resist) disposed on a substrate.
[0005] The minimum size of a feature that can be formed on a substrate is determined by the wavelength of radiation used by the lithography equipment to project a pattern onto the substrate. Compared to conventional lithography equipment (which may, for example, use electromagnetic radiation with a wavelength of 193 nm), lithography equipment using EUV radiation with wavelengths in the range of 4 nm to 20 nm can be used to form smaller features on the substrate.
[0006] Photolithography equipment includes patterning apparatus (e.g., a mask or photomask). Radiation is provided to pass through or is reflected from the patterning apparatus to form an image on a substrate. A diaphragm assembly (also called a surface film) may be provided to protect the patterning apparatus from airborne particles and other forms of contaminants. Contamination on the surface of the patterning apparatus can cause manufacturing defects on the substrate.
[0007] A coating can also be provided to protect optical components other than the patterning apparatus. The coating can also be used to provide pathways for lithographic radiation between sealed areas of a lithography apparatus. The coating can also be used as a filter (such as a spectral purity filter) or as part of a dynamic gas lock in a lithography apparatus.
[0008] A mask assembly may include a surface film that protects a pattern forming apparatus (e.g., a mask) from particle contamination. The surface film may be supported by a surface film frame, thereby forming the surface film assembly. The surface film may be attached to the frame, for example, by gluing or otherwise attaching a surface film boundary region to the frame. The frame may be permanently or releasably attached to the pattern forming apparatus.
[0009] Since the pellicle is present in the optical path, i.e. the optical path, of the EUV radiation beam, the pellicle must have a high EUV transmissivity. A high EUV transmissivity allows a larger proportion of the incident radiation to pass through the pellicle and the amount of EUV radiation absorbed by the pellicle can be reduced, which can lower the operating temperature of the pellicle. Since the transmissivity depends at least in part on the thickness of the pellicle, it is desirable to provide a pellicle that is as thin as possible while maintaining a reliable strength to withstand the sometimes adverse environment within the lithographic apparatus. The pellicle membrane also needs to be strong enough to withstand forces acting on it when being transported and when in use. The pellicle membrane also needs to avoid deformation into an image, to avoid contamination of critical scanner components such as by outgassing, and also to avoid deflection beyond predetermined specified limits.
[0010] The present invention has sought to be designed to address at least some of the problems identified above. SUMMARY
[0011] According to a first aspect of the present disclosure, there is provided a pellicle membrane for a lithographic apparatus, the pellicle membrane comprising a core comprising a metal silicon carbonitride. The metal silicon carbonitride can also be defined as a MetalSi y C b N z crystal embedded in a Si y matrix, wherein b, y, z > 0. Preferably, the metal silicon carbonitride has the formula Me a Si y C b N z wherein a, b, y, z > 0. It will be appreciated that the formula can be stoichiometric, however non-stoichiometric variants are also envisaged. The exact amounts can be adjusted depending on the nature of the metal in the compound and the operating conditions intended for the pellicle.
[0012] Various material combinations for both the crystal and the matrix can be envisaged. In one variant, the metal silicide has a higher thermal emissivity than the matrix material, but alternatives where the matrix material has a higher thermal emissivity are also possible. Suitable metal silicides are for example NbSi2, MoSi2, Mo5Si3, Mo3Si, TiSi2, WSi2, NiSi2, PtSi, CoSi2and TaSi2. These silicides are generally emissive, with TiSi2having a smaller emissivity. Other silicides can also be suitable, such as silicides of Pd, Ta or V.
[0013] The metal Me can be selected from one or more of niobium, molybdenum, titanium, tungsten, platinum, cobalt, tantalum, palladium or vanadium. Preferably, the metal is molybdenum. Non-limiting examples are Mo5Si3CxNy, MoSi2CN, Mo3SiCN, including other stoichiometric and non-stoichiometric variants.
[0014] The core of the pellicle membrane provides the necessary physical properties to the pellicle to allow the membrane to withstand the environment within a lithographic apparatus. In particular, the core provides mechanical strength to withstand deflection caused by unbalanced forces acting on the membrane, such as deflection caused by different pressures exerted on different faces of the membrane. It has been found that partially nitriding a metal silicide core, such as a molybdenum silicide, to thereby form a metal silicon nitride core can improve the properties of a pellicle membrane. In particular, without wishing to be bound by scientific theory, it is believed that the metal silicide crystals in the metal silicon nitride core provide thermal emissivity, ductility, and stiffness, which are all beneficial properties. Even so, the metal silicide crystals also provide brittleness and high tensile mechanical pre-stress, which are undesirable. It is believed that adding nitrogen to the metal silicide during growth of the material provides a silicon-rich amorphous silicon nitride phase that segregates when the material is annealed, which provides a matrix with a more relaxed stress state due to the excess silicon, thereby reducing the global mechanical pellicle pre-stress. In addition, Metal Si yThe value of y in Si2N4ydecreases from about 2 to about 0.6, which reduces the pre-stress and increases the emissivity. The addition of nitrogen reduces the transmissivity to EUV radiation and thus reduces the production throughput yield of the scanner / lithography apparatus alone. While the metal silicon nitride pellicle membrane has certain advantages, there can still be some problems. For example, the number of ruptures of the pellicle membrane can increase during manufacturing. Further, these pellicles outgas material, including silicon and nitrogen, from the core material, which can contaminate critical components of the lithography apparatus. These pellicles can also suffer from excessive sag and sag drift over time during exposure, and can also oxidize during use and during storage, which reduces the scanner throughput yield. It has been found that a core comprising metal silicon carbonitride resolves many of the problems of existing pellicle membranes. The metal silicon carbonitride core of the present disclosure has improved robustness compared to existing pellicle membranes, and has a reduced likelihood of rupture during manufacturing, even at very low pellicle thicknesses. In addition, it has been found that such core pellicles have an improvement of about 1% to 1.5% in EUV transmissivity compared to equivalent metal silicon nitride pellicles. In addition, it has been found that these pellicles are stable during storage for at least 5 years under ambient conditions. Existing pellicle membranes continue to oxidize during storage under ambient conditions, which increases the thickness of the native oxide layer and reduces the EUV transmissivity, which is undesirable. The metal silicon carbonitride pellicle also has a thermal emissivity of about 30% or more, which is well suited for use as a pellicle in a lithography apparatus, especially an EUV lithography apparatus. The mechanical pre-stress of the metal silicon carbonitride pellicle can also be tuned to a value of about 200 MPa to about 600 MPa, which is also well suited for use as a pellicle in a lithography apparatus, especially an EUV lithography apparatus. The yield strength of the pellicle comprising the metal silicon carbonitride core is from about 3 GPa to 4 GPa, which is high enough for use in a lithography apparatus. Preferably, the metal is molybdenum.
[0015] The pellicle can comprise a silicon oxycarbonitride capping layer. It has been found that such a silicon oxycarbonitride layer is a very stable oxide layer that exhibits high hardness and good barrier properties, and also has lower compressive stress compared to silicon oxide. In addition, the etch rate of silicon oxycarbonitride in 0.5% HF acid etchant is about 2 nm / h, which is about ten times slower than silicon dioxide. As such, it is more resistant to chemical corrosion and can be used as an etch stop layer, as opposed to a silicon dioxide capping layer, which etches under operating conditions within a lithography apparatus.
[0016] According to a second aspect of the present disclosure, there is provided a pellicle membrane for a lithography apparatus, wherein the pellicle membrane comprises a silicon oxycarbonitride capping layer and a core. Optionally, the core comprises a metal silicon carbonitride. The metal can be selected from one or more of niobium, molybdenum, titanium, tungsten, platinum, cobalt, tantalum, palladium, or vanadium.
[0017] As mentioned in relation to the first aspect of the disclosure, the silicon oxycarbonitride capping layer is a very stable oxide layer with high hardness and good barrier properties, and also has lower compressive stress compared to silicon oxide. Additionally, the etch rate of silicon oxycarbonitride in 0.5% HF acid etchant is about 2 nm / h, which is about ten times slower than silicon dioxide. As such, it is more resistant to chemical corrosion and can be used as an etch stop layer, as opposed to a silicon dioxide capping layer which etches under operating conditions within a lithography apparatus.
[0018] The features described below are relevant to each of the first and second aspects of the disclosure. Reference to a metal can include one or more of niobium, molybdenum, titanium, tungsten, platinum, cobalt, tantalum, palladium or vanadium.
[0019] The pellicle membrane can comprise a-SiO x C y N z Capping layer, where 0 < x < 2, 0 < y < 1 and 0 < z < 1.33. It will be appreciated that the formula can not be stoichiometric.
[0020] The core can comprise a metal silicide and a silicon carbonitride. The metal can be selected from one or more of niobium, molybdenum, titanium, tungsten, platinum, cobalt, tantalum, palladium or vanadium, preferably molybdenum. The core can further comprise silicon, silicon nitride and / or silicon carbide. It will be appreciated that the composition of the core is not necessarily uniform at all times and can be a composite material comprising different phases.
[0021] The core layer can comprise metal silicide crystals in a silicon carbonitride matrix. The metal can be selected from one or more of niobium, molybdenum, titanium, tungsten, platinum, cobalt, tantalum, palladium or vanadium, preferably molybdenum. Without wishing to be bound by scientific theory, it is believed that the molybdenum silicide crystals provide emissivity to the core, which reduces the operating temperature of a pellicle comprising such a core at a given power level. This is advantageous because the additional emissivity allows a pellicle comprising such a core to be operated at a higher power or at the same power resulting in a lower operating temperature of the pellicle. It has been found that including carbon and nitrogen in the silicon matrix is advantageous because it reduces outgassing, improves manufacturability and provides desirable pre-tension characteristics and resistance to sagging or wrinkling.
[0022] The membrane can have a thickness of from about 5 nm to about 50 nm, from about 5 nm to about 25 nm, from about 8 nm to about 20 nm, or from about 10 to about 15 nm. Since the pellicle membrane is in the path of the radiation beam used in lithography, it is desirable to make the pellicle membrane as thin as possible to minimise absorption of the radiation, while at the same time ensuring that the pellicle membrane is strong enough to withstand the environment within a lithography apparatus.
[0023] The metal may be present in the membrane in amounts ranging from about 10% to about 40%, from about 15% to about 35%, from about 18% to about 32%, or from about 21% to about 30% (atomic %).
[0024] Silicon may be present in the membrane in amounts ranging from about 30% to about 65%, from about 32% to about 60%, from about 34% to about 55%, or from about 37% to about 51% (atomic %).
[0025] Nitrogen may be present in the membrane in amounts ranging from about 2% to about 40%, from about 5% to about 30%, from about 8% to about 28%, or from about 10% to about 25% (atomic %).
[0026] Carbon may be present in the membrane in amounts ranging from about 2% to about 40%, from about 5% to about 36%, from about 8% to about 33%, or from about 10% to about 30% (atomic %).
[0027] The membrane diaphragm may include capping layers on two sides. The two capping layers may comprise silicon oxide carbonitrides. In other embodiments, the capping layers on each side are different.
[0028] The capping layer can be self-assembly. By self-assembly, it should be understood that the capping layer forms naturally when the core material is exposed to oxygen. Alternatively, the capping layer can be formed by sputtering.
[0029] The cover layer may have a thickness from about 1 nm to about 5 nm, from about 2 nm to about 4 nm, or about 3 nm.
[0030] According to a third aspect of this disclosure, a surface film for a photolithography apparatus is provided, the surface film including a surface film diaphragm according to a first or second aspect of this disclosure and a support frame for supporting the surface film diaphragm.
[0031] According to a fourth aspect of this disclosure, a photolithography apparatus is provided, including a diaphragm or a film according to any one of the first to third aspects of this disclosure.
[0032] According to a fifth aspect of this disclosure, a method for manufacturing a membrane diaphragm is provided, the method comprising sputtering a metal silicide target and a silicon carbide target in a nitrogen-containing gas stream to form a molybdenum silicon carbonitride core. The metal may be selected from one or more of niobium, molybdenum, titanium, tungsten, platinum, cobalt, tantalum, palladium, or vanadium, preferably molybdenum.
[0033] The method may include changing the concentration of nitrogen in the airflow to control the amount of nitrogen included in the core.
[0034] According to a sixth aspect of the present disclosure, there is provided use of a pellicle membrane, pellicle or lithographic apparatus according to any of the first to fourth aspects of the present disclosure or method according to the fifth aspect of the present disclosure in a lithographic method or apparatus.
[0035] It will be appreciated that features described in relation to one aspect can be combined with any of the features described in relation to another aspect, and all such combinations are explicitly contemplated and disclosed herein. BRIEF DESCRIPTION OF DRAWINGS
[0036] Embodiments of the application will now be described, by way of example only, with reference to the accompanying schematic drawings, in which corresponding reference signs indicate corresponding parts, and in which:
[0037] Figure 1 depictions of a lithographic apparatus according to aspects of the present disclosure;
[0038] Figure 2 is a schematic depiction of a pellicle according to aspects of the present disclosure; and
[0039] Figure 3a and Figure 3b are STEM images of a 20 nm MoSiC layer taken in bright field (3a) and high angle annular dark field (3b).
[0040] The features and advantages of the present disclosure will become apparent from the detailed description, set out below, taken in conjunction with the accompanying drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and / or structurally similar elements. The drawing in which each feature was introduced is indicated by the left-most digit(s) in the lower right corner of each figure. DETAILED DESCRIPTION
[0041] Figure 1A lithographic system according to the application is shown. The lithographic system comprises a radiation source SO and a lithographic apparatus LA. The radiation source SO is configured to generate an extreme ultraviolet (EUV) radiation beam RB. The lithographic apparatus LA includes an illumination system IL, a support structure MT configured to support a patterning device MA, e.g. a mask, a projection system PS and a substrate table WT configured to support a substrate W. A heater (not shown) can be provided at any suitable location, such as in the illumination system IL or the projection system PS, to provide thermal energy to a substrate W, such as a wafer, positioned on the substrate table WT. The illumination system IL is configured to condition the radiation beam RB before the radiation beam RB is incident upon the patterning device MA. The projection system is configured to project the radiation beam RB, now patterned by the mask MA, onto the substrate W. The substrate W can include previously formed patterns. In such cases, the lithographic apparatus will align the patterned radiation beam RB with a pattern previously formed on the substrate W. In this embodiment, a pellicle 15 is depicted in the path of the radiation and protects the patterning device MA. It will be appreciated that the pellicle 15 can be located in any desired position and can be used to protect any of the mirrors in the lithographic apparatus. The patterning device MA can be referred to as a mask. The support structure MT can be referred to as a mask table.
[0042] The radiation source SO, the illumination system IL, and the projection system PS can each be constructed and arranged such that they isolate the EUV radiation from the outside environment. A gas, e.g., hydrogen, at a pressure below atmospheric pressure can be provided in the radiation source SO. A vacuum can be provided in the illumination system IL and / or the projection system PS. A small amount of gas, e.g., hydrogen, at a pressure that is sufficiently below atmospheric pressure can be provided in the illumination system IL and / or the projection system PS.
[0043] Figure 1 The radiation source SO shown in Fig. 1 is of a type which can be referred to as a laser produced plasma (LPP) source. A laser, which can for example be a CO2laser, is arranged to store energy via a laser beam into a fuel, such as tin (Sn), provided from a fuel emitter. Although tin is mentioned in the following description, any suitable fuel can be used. The fuel can for example be in liquid form and can for example be a metal or an alloy. The fuel emitter can comprise a nozzle configured to direct the tin, for example in the form of droplets, along a trajectory towards a plasma formation region. The laser beam is incident on the tin at the plasma formation region. The storage of laser energy into the tin creates a plasma at the plasma formation region. Radiation, including EUV radiation, is emitted from the plasma during de-excitation and recombination of ions of the plasma.
[0044] EUV radiation is collected and focused by a near-normal incidence radiation collector (sometimes referred to more generally as a normal incidence radiation collector). The collector can have a multilayer structure arranged to reflect EUV radiation (e.g. EUV radiation having a desired wavelength such as 13.5 nm). The collector can have an elliptical configuration with two elliptical focal points. The first focal point can be at a plasma formation region and the second focal point can be at an intermediate focus point, as discussed below.
[0045] The laser can be separate from the radiation source SO. In such cases, the laser beam can be passed from the laser to the radiation source SO with the aid of a beam delivery system (not shown) which can include, for example, suitable directing mirrors and / or a beam expander and / or other optical components. The laser and the radiation source SO can together be considered to form a radiation system.
[0046] Radiation reflected by the collector forms a radiation beam RB. The radiation beam B is focused to a spot to form an image of the plasma formation region which acts as a virtual radiation source for the illumination system IL. The spot at which the radiation beam RB is focused can be referred to as the intermediate focus. The radiation source SO is arranged such that the intermediate focus is located at or near an opening in an enclosing structure of the radiation source.
[0047] The radiation beam RB passes from the radiation source SO into an illumination system IL which is configured to condition the radiation beam. The illumination system IL can include a facetted field mirror device 10 and a facetted pupil mirror device 11. The facetted field mirror device 10 and facetted pupil mirror device 11 together provide the radiation beam RB with a desired cross-sectional shape and a desired angular distribution. The radiation beam RB passes from the illumination system IL and is incident on the patterning device MA held by the support structure MT. The patterning device MA reflects and patterns the radiation beam RB. The illumination system IL can also include other mirrors or devices in addition to or instead of the facetted field mirror device 10 and facetted pupil mirror device 11. A heater can be positioned and configured to supply thermal energy to the substrate W reflected by one or more of the mirror devices.
[0048] After reflection from the patterning device MA, the patterned radiation beam RB enters the projection system PS. The projection system includes a plurality of mirrors 13, 14 configured to project the radiation beam RB onto a substrate W held by the substrate table WT. The projection system PS can apply a reduction factor to the radiation beam, forming an image with features smaller than the corresponding features on the patterning device MA. For example, a reduction factor of 4 can be applied. Although the projection system PS is in Figure 1The projection system in the figure has two mirrors 13, 14, but the projection system can include any number of mirrors (e.g., six mirrors).
[0049] Figure 1 The radiation source SO shown in the figure can include components not shown. For example, a spectral filter can be provided in the radiation source. The spectral filter can be substantially transmissive to EUV radiation, but substantially blocks other wavelengths, such as infrared radiation.
[0050] If the patterning device MA is not protected, the contamination can require cleaning or discarding of the patterning device MA. Cleaning the patterning device MA interrupts valuable manufacturing time, and discarding the patterning device MA is costly. Replacing the patterning device MA also interrupts valuable manufacturing time.
[0051] Figure 2 is a schematic depiction of a pellicle assembly 15 according to the present disclosure. The pellicle assembly includes a support 16 configured to support the pellicle membrane 17. In the figure, the support 16 is presented as two separate elements, but this need not necessarily be the case, and the support 16 can be in the form of a border that encloses the pellicle membrane 17. The pellicle membrane 17 includes a cap layer 18 configured to protect the pellicle membrane 17, especially the emissive core 19, from degradation. The cap layer can be a silicon oxycarbonitride cap layer. The emissive core 19 includes a matrix 20 that provides the required pre-tension and strength, such a matrix can include silicon carbonitride as a silicon carbide that includes additional nitrogen. The matrix material 20 can include one or more of elemental silicon, silicon oxide, and silicon nitride. The emissive layer 19 includes a heat emissive crystal 21 disposed within the matrix 20. The heat emissive crystal 21 is included to increase the emissivity of the pellicle membrane 17, thereby allowing the pellicle membrane to operate at a lower temperature than would otherwise be the case at a given power, or to operate at the same temperature as a pellicle membrane that does not include an emissive crystal but at a higher power. The heat emissive crystal 21 can include a metal silicide, such as a molybdenum silicide. As such, the core 19 can be a molybdenum silicon carbonitride composite core material that includes a molybdenum silicide in a silicon carbonitride matrix. In other embodiments, the molybdenum can be replaced by any one or more of the metals described herein. In Figure 2 In the figure, the cap layer 18 is depicted as completely enclosing the emissive core 19. It will be appreciated that in some embodiments, the cap layer 18 is only disposed on one or both faces of the emissive core 19 and can not extend around the edges.
[0052] Figure 3aFigure 3 depicts complementary STEM images of a 20 nm MoSiC layer in bright field (3a) and high angle annular dark field (3b). The images depict irregularly shaped molybdenum silicide crystals in the MoSiC layer. This is believed to be similar to the structure of the MoSiCN layer material of the present disclosure. It is believed that the addition of nitrogen reduces the grain size of the molybdenum as SiN can also be formed in addition to SiC and molybdenum silicides.
[0053] In summary, the present disclosure provides a new core material for pellicle membranes in lithography apparatuses. The new core material exhibits improved EUV transmissivity compared to existing materials. The core material also exhibits a suitable emissivity and can tune the pre-tension, which is suitable for use in EUV lithography apparatuses. Such a core material also creates a native oxide layer, which serves to reduce or eliminate outgassing of the core material, such as silicon or nitrogen, which can contaminate critical components of the lithography apparatus. The core material of the present disclosure also has increased robustness, meaning that there is little or no breakage during manufacturing, even at very low pellicle thicknesses. Similarly, the present disclosure also provides a cap or cover layer, which protects the core material from conditions within the EUV lithography apparatus and serves to reduce or eliminate outgassing of material from the core. Such a cover layer is also suitable for use in pellicle membranes, which are used as dynamic airlock membranes. The cover layer also prevents oxidation of the core material and thereby limits the degradation of EUV transmissivity over time.
[0054] While specific embodiments of the application have been described above, it will be appreciated that the application can be practiced otherwise than as described.
[0055] The above description is intended to be illustrative, and not restrictive. Thus, it will be apparent to those skilled in the art that modifications can be made to the application as described without departing from the scope of the claims as set forth below.
Claims
1. A pellicle membrane for a lithographic apparatus, the pellicle membrane comprising a core comprising a metal silicon carbonitride.
2. The pellicle membrane of claim 1, wherein, the metal is selected from one or more of niobium, molybdenum, titanium, tungsten, platinum, cobalt, tantalum, palladium, or vanadium.
3. The pellicle membrane of claim 1 or claim 2, wherein, the pellicle membrane comprises a silicon oxycarbonitride capping layer.
4. A pellicle membrane for a lithographic apparatus, wherein, the pellicle membrane comprises a silicon oxycarbonitride capping layer and a core, optionally wherein the core comprises a metal silicon carbonitride, optionally wherein the metal is selected from one or more of niobium, molybdenum, titanium, tungsten, platinum, cobalt, tantalum, palladium, or vanadium.
5. The pellicle membrane of any preceding claim, wherein, The pellicle barrier includes α-SiO x C y N z A cover layer, where 0 < x ≤ 2, 0 < y ≤ 1, and 0 < z ≤ 1.
33.
6. The pellicle membrane of any preceding claim, wherein, the core comprises a metal silicide and a silicon carbonitride, optionally wherein the layer further comprises silicon, silicon nitride, and / or silicon carbide.
7. The pellicle membrane of any preceding claim, wherein, the core layer comprises metal silicide crystals in a silicon carbonitride matrix.
8. The pellicle membrane of any preceding claim, wherein, the pellicle membrane has a thickness of about 5 nm to about 50 nm, about 5 nm to about 25 nm, about 8 nm to about 20 nm, or about 10 nm to about 15 nm.
9. The pellicle membrane of any preceding claim, wherein, the metal is present in the pellicle membrane in an amount of from about 10% to about 40%, from about 15% to about 35%, from about 18% to about 32%, or from about 15% to about 30% (atomic %).
10. The pellicle membrane of any preceding claim, wherein, silicon is present in the pellicle membrane in an amount of from about 30% to about 65%, from about 32% to about 60%, from about 34% to about 55%, or from about 37% to about 51% (atomic %).
11. The pellicle membrane of any preceding claim, wherein, nitrogen is present in the pellicle membrane in an amount of from about 2% to about 40%, from about 5% to about 30%, from about 8% to about 28%, or from about 10% to about 25% (atomic %).
12. The pellicle membrane of any preceding claim, wherein, carbon is present in the pellicle membrane in an amount of from about 2% to about 40%, from about 5% to about 36%, from about 8% to about 33%, or from about 10% to about 30% (atomic %).
13. The pellicle membrane of any preceding claim, wherein, the pellicle membrane comprises a capping layer on both faces, optionally wherein both capping layers comprise a silicon oxycarbonitride.
14. The pellicle membrane of any one of claims 2-13, wherein, the capping layer is self-assembled.
15. The pellicle membrane of any one of claims 13-14, wherein, the capping layer has a thickness of from about 1 nm to about 5 nm, from about 2 nm to about 4 nm, or about 3 nm.
16. A pellicle for a lithographic apparatus, the pellicle comprising a pellicle membrane according to any preceding claim and a support frame for supporting the pellicle membrane.
17. A lithographic apparatus comprising a pellicle membrane or pellicle according to any of claims 1 to 16.
18. A method of manufacturing a pellicle membrane, the method comprising sputtering a metal silicide target and a silicon carbide target in a gas stream comprising nitrogen to form a metal silicon carbonitride core, optionally wherein the metal is selected from one or more of niobium, molybdenum, titanium, tungsten, platinum, cobalt, tantalum, palladium, or vanadium.
19. The method according to claim 18, wherein, the method comprises varying the concentration of nitrogen in the gas stream to control the amount of nitrogen included in the core.
20. Use of a pellicle membrane, pellicle, or lithographic apparatus according to any of claims 1 to 17 or a method according to any of claims 18 and 19 in a lithographic method or apparatus.