Pellicle film

Abstract

There is provided a pellicle film for an exposure apparatus, wherein the pellicle film comprises MoSi2 and Mo5Si3 crystals dispersed in an amorphous matrix, wherein the pellicle film is characterized by one or both of: i) 70% or more MoSi2 crystals and 30% or less Mo5Si3; crystals as a volume percentage of a total volume of MoSi2 crystals and Mo5Si3; crystals in the film; and ii) a multi-layered microstructure. Also described is a pellicle assembly for an exposure apparatus, such as a lithographic apparatus, the pellicle assembly including such a pellicle film and a support frame for supporting the pellicle film. There is also provided an exposure apparatus comprising such a pellicle or pellicle film. A method of manufacturing a pellicle film, wherein the method comprises deposition of material layers to form a pellicle film according to the invention.

Description

PELLICLE FILMCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of EP application 24167365.6 which was filed on 28 March2024 and which is incorporated herein in its entirety by reference.FIELD

[0002] The present disclosure relates to a pellicle film for an exposure apparatus, in particular an extreme ultraviolet (EUV) exposure apparatus. The present disclosure also relates to a pellicle for an exposure apparatus as well as an exposure apparatus comprising such a pellicle film. Also described is a method of manufacturing a pellicle film as well as the use of such a pellicle film, pellicle, exposure apparatus or method in an EUV exposure method or apparatus. The present disclosure has particular, but not exclusive application, to EUV exposure apparatus such as EUV utilization apparatus, for example EUV lithography apparatuses or inspection tools.BACKGROUND

[0003] A lithographic apparatus is a machine constructed to apply a desired pattern onto a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus may, for example, project a pattern at a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) provided on a substrate.

[0004] To project a pattern on a substrate a lithographic apparatus may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features which can be formed on the substrate. A lithographic apparatus, which uses extreme ultraviolet (EUV) radiation, having a wavelength within the range 4-20 nm, for example 6.7 nm or 13.5 nm, may be used to form smaller features on a substrate than a lithographic apparatus which uses, for example, radiation with a wavelength of 193 nm.

[0005] A patterning device (e.g., a mask or reticle) is used to impart a pattern to a radiation beam in a lithographic apparatus. The patterning device may be protected by a pellicle from particle contamination. The pellicle may be supported by a pellicle frame.

[0006] A typical pellicle comprises a film which is located away from the patterning device and is out of the focal plane of a lithographic apparatus in use. Since the film is offset from the focal plane of the lithographic apparatus, contamination particles which land on the pellicle are held out of the lithographic apparatus focal plane. Consequently, (focused) images of contamination particles are not projected onto the substrate. If the pellicle were not present, contaminating particles landing on the patterning device would be projected onto the substrate, introducing a defect into the projected pattern.

[0007] EUV pellicles may be made from a plurality of composite materials. In an example, the EUV pellicle may be a composite comprising molybdenum silicide crystals in another EUVtransmissive matrix. Known composite EUV pellicles may be fragile and have low reliability. Pellicle breakages can often occur during transport, handling, and operation. For example, in operation in a lithographic apparatus, the pellicle may be subjected to mechanical, thermal and / or chemical stresses, leading to breakage.

[0008] The present invention has been devised in an attempt to address at least some of the problems identified above.SUMMARY

[0009] According to a first aspect of the present disclosure, there is provided a pellicle film for an exposure apparatus, wherein the pellicle film comprises MoSiz and MozSi ; crystals dispersed in an amorphous matrix, wherein the pellicle film is characterized by one or both of: i) 70% or more MoSiz crystals and 30% or less MozSi ; crystals as a volume percentage of a total volume of MoSiz crystals and MozSi ; crystals in the film; and ii) a multi-layered microstructure.

[0010] In order to function as a pellicle film, the film must be able to withstand the environment of an EUV exposure apparatus, such as an EUV lithography apparatus, which includes EUV radiation, temperatures which can be 600°C or higher, and the presence of hydrogen plasma. The pellicle film needs to be highly EUV transmissive, such as greater than 90% (single -pass) EUV transmissivity and also be able to withstand any thermo-mechanical forces acting upon it in nominal use. It should also be able to accommodate deformation to a specified level without rupture in order to meet lifetime performance and reliability specifications, and avoid introducing contaminants into the apparatus. Whilst the strength and stiffness of a film could be increased by increasing the thickness of the film, this would lead to a significant reduction in EUV transmissivity. The existing very thin films with a thickness in the order of around 10-20 nm can be fragile and prone to breaking. Without wishing to be bound by scientific theory, it is believed that such films are susceptible to cracking due to their composite nature as cracks can propagate through and along the interface between crystals and the matrix and weak points such as holes or cracks which exist as a by-product of manufacturing can initiate cracks. It is possible to strengthen brittle materials by optimizing the intrinsic microstructure of the film via optimization of the composition and microstructure. According to the present disclosure, it has been found that controlling the relative ratio of MoSiz and MozSi ; crystals in a pellicle film can provide improvements in the strength and toughness of a pellicle film. In particular, for a film comprising MoSiz and MozSi ; crystals within a matrix material, having 70 vol% of more of the MoSiz crystals and 30 vol% or less MozSi ; crystals, it has been found that the film is more resistant to cracking. It will be appreciated that the vol% is measured as the volume of the combined MoSiz and MozSi ; crystals, not as a percentage of the volume of the entire film. As such, the total of the volume fraction of the MoSiz and MozSi ; crystals will always be 100%. MozSi ; crystals are more likely to be the detrimental sites for cracking (in addition to existing holes / defects) and have been observed to demonstrate intergranular cracking as well as transgranular cracking. On the other hand, MoSiz appear to be more crack resistantas cracks do not appear to propagate transgranularly (within the grains) but rather only along a phase boundary. It is observed that MoSiz is more ductile and therefore able to constrain crack growth as compared to the MozSi ; phase. In existing pellicle films comprising MoSiz and MozSi ; crystals, there is a greater proportion of MozSi ; crystals, whereas in the present disclosure, a greater proportion of MoSi z crystals is provided. The advantage of the present disclosure include promotion of crack blunting (suppression) in the in-plane direction of the film and therefore prevention of formation of a merged crack network, suppression of progression of cracks in plane even if micro-cracks form along the thickness of the film, higher toughness due to the dominance of the more ductile MoSiz. as well as a reduction in triple junctions between the matrix material and the MoSi 2 and MozSi ; crystals as potential sites for cracking.

[0011] It has been found that improvements in the toughness of a pellicle film can additionally or alternatively be realized by the provision of a multilayered microstructure. By avoiding a structure comprising single grains in the thickness of the film, crack propagation is suppressed. In addition, a multilayered microstructure provides some level of plasticity to the film and the harder MozSi ; phase is somewhat more isolated, which further suppresses crack growth. Furthermore, such multi-layered microstructures exhibit prevalent shear deformation by sliding due to introduction of larger surface area along the in-plane direction as tensile forces are applied in-plane.

[0012] At least some of the MoSiz crystals may be elongate. As at least some of the MoSiz crystals are elongate, they will have a major axis, which is the axis through the longest portion of the crystals. The major axis may be aligned in-plane. In this configuration, in-plane crack propagation is suppressed. The MoSiz crystals may have an aspect ratio of 3 or more.

[0013] The pellicle film may include an interlayer. The interlayer may be selected from one or more of zirconium oxide, carbon, or yttrium silicon oxide. The interlayer may be more ductile that the other materials within the film. In this way, the interlayer acts as a more ductile layer and accommodates the majority of the strain, thereby reducing the stress concentration, particularly in the hard MozSi ; material. Zirconium oxide may be ZrOz. Yttrium silicon oxide may be YzSiOs.

[0014] Advantageously, pellicle films having a MoSiz-dominant and / or multi-layered microstructure are much more crack resistant relative to existing films. This increases the lifetime of the pellicle film.

[0015] The average grain size of the MoSiz crystals may be from about 50 nm to about 100 nm. The average grain size of the MozSi ; crystals may be less than about 10 nm.

[0016] Advantageously, reducing the average grain size improves the fracture toughness of brittle materials.

[0017] The amorphous matrix may comprise silicon nitride.

[0018] The thickness of the pellicle film may be from about 10 nm to about 20 nm, such as from about 5 nm to about 20 nm.

[0019] According to a second aspect of the present disclosure, there is provided a pellicle for an exposure apparatus, the pellicle including a pellicle film according to the first aspect of the present disclosure and a support for the pellicle film.

[0020] According to a third aspect of the present disclosure, there is provided an exposure apparatus comprising the pellicle film according to the first aspect of the pellicle according to the second aspect of the present disclosure.

[0021] According to a fourth aspect of the present disclosure, there is provided a method of manufacturing a pellicle film, wherein the method comprises deposition of material layers to form a pellicle film, characterised by one or both of: 70% or more MoSiz crystals and 30 % or less Mo Si ; crystals as a volume percentage of a total volume of MoSiz crystals and Mo^Si ; in the film; and ii) a multi-layered microstructure. The deposition of material layers may be via any suitable route, such as, for example a physical vapour deposition process, such as sputtering.

[0022] The method may include varying one or more of a molybdenum content of a target, a nitrogen concentration of a sputtering gas stream and an annealing temperature.

[0023] The method may comprise depositing an interlayer, optionally wherein the one or more layers are selected from one or more of zirconium oxide, carbon or yttrium silicon oxide.

[0024] According to a fifth aspect of the present disclosure, there is provided the use of a pellicle film according to the first aspect, a pellicle according to the second aspect, an exposure apparatus according to the third aspect, or a method according to the fourth aspect in an EUV exposure method or apparatus.

[0025] It will be appreciated that features described in respect of one embodiment may be combined with any features described in respect of another embodiment and all such combinations are expressly considered and disclosed herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:Figure 1 depicts a lithographic system comprising a lithographic apparatus and a radiation source;Figure 2 schematically depicts a pellicle assembly in a cross-sectional view;Figure 3 schematically depicts a lateral cross-section of the microstructure of a pellicle film according to an embodiment of the present disclosure;Figure 4a schematically depicts a transverse cross-section of the microstructure of a pellicle film according to another embodiment of the present disclosure; andFigure 4b schematically depicts a transverse cross-section of the microstructure of a pellicle film according to another embodiment of the present disclosure.

[0027] The features and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the 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 elementsDETAILED DESCRIPTION

[0028] Figure 1 shows a lithographic system comprising a radiation source SO and a lithographic apparatus LA. The radiation source SO is configured to generate an EUV radiation beam B and to supply the EUV radiation beam B to the lithographic apparatus LA. The lithographic apparatus LA comprises 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.

[0029] The illumination system IL is configured to condition the EUV radiation beam B before the EUV radiation beam B is incident upon the patterning device MA. Thereto, the illumination system IL may include a facetted field mirror device 10 and a facetted pupil mirror device 11. The faceted field mirror device 10 and faceted pupil mirror device 11 together provide the EUV radiation beam B with a desired cross-sectional shape and a desired intensity distribution. The illumination system IL may include other mirrors or devices in addition to, or instead of, the faceted field mirror device 10 and faceted pupil mirror device 11. The patterning device MA is protected by a pellicle assembly 15.

[0030] After being thus conditioned, the EUV radiation beam B interacts with the patterning device MA. As a result of this interaction, a patterned EUV radiation beam B’ is generated. The projection system PS is configured to project the patterned EUV radiation beam B’ onto the substrate W. For that purpose, the projection system PS may comprise a plurality of mirrors 13,14 which are configured to project the patterned EUV radiation beam B’ onto the substrate W held by the substrate table WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B ’ , thus forming an image with features that are smaller than corresponding features on the patterning device MA. For example, a reduction factor of 4 or 8 may be applied. Although the projection system PS is illustrated as having only two mirrors 13,14 in Figure 1, the projection system PS may include a different number of mirrors (e.g. six or eight mirrors).

[0031] The substrate W may include previously formed patterns. Where this is the case, the lithographic apparatus LA aligns the image, formed by the patterned EUV radiation beam B’, with a pattern previously formed on the substrate W.

[0032] A relative vacuum, i.e. a small amount of gas (e.g. hydrogen) at a pressure well below atmospheric pressure, may be provided in the radiation source SO, in the illumination system IL, and / or in the projection system PS.

[0033] The radiation source SO may be a laser produced plasma (LPP) source, a discharge produced plasma (DPP) source, a free electron laser (FEL) or any other radiation source that is capable of generating EUV radiation.

[0034] Figure 2 schematically illustrates the pellicle assembly 15 in situ on the patterning device MA. The pellicle assembly comprises a pellicle film 19 according to an embodiment of the present disclosure that is held in place by a pellicle frame 17.

[0035] The pellicle film 19 is provided in the path of both the incident radiation beam B and the reflected patterned radiation beam B’. The radiation beam passes through the pellicle film 19 twice. The pellicle film 19 is substantially transmissive to EUV radiation (although it will absorb a small amount of EUV radiation). The pellicle film 19 acts to protect the patterning device MA from particle contamination. Whilst efforts may be made to maintain a clean environment inside the lithographic apparatus LA, particles may still be present inside the lithographic apparatus LA. In the absence of the pellicle film 19, particles may be deposited onto the patterning device MA. Particles on the patterning device MA in the focal plane of the lithographic apparatus may disadvantageously impact the pattern that is imparted to the radiation beam B and therefore the pattern that is transferred to the substrate W. The pellicle film 19 provides a barrier between the patterning device MA and the environment in the lithographic apparatus LA in order to prevent particles from being deposited on the patterning device MA.

[0036] In use, the pellicle film 19 of the pellicle assembly 15 is positioned at a distance from the patterning device MA by the pellicle frame 17. The distance is sufficient to separate particles (e.g. particle 22) incident upon the surface of the film from the focal plane of the radiation beam B. The distance between the pellicle film 19 and the patterning device MA, acts to reduce the extent to which any particles on the surface of the pellicle 19 impart a pattern to the radiation beam B. A particle present in the beam of radiation B, but not at a focal plane of the beam of radiation B (i.e., not at the surface of the patterning device MA), will not be in focus at the surface of the substrate W. In the absence of other considerations, it may be desirable to position the film a considerable distance away from the patterning device MA. However, in practice the space which is available in the lithographic apparatus LA to accommodate the pellicle assembly 15 is limited due to the presence of other components.

[0037] Pellicle film compositions may be molybdenum silicon nitride -based. In particular, existing pellicle films may comprise MosSis and MoSiz crystals dispersed in an amorphous matrix of silicon nitride, wherein Mo Si ; is the dominant microstructural component. Known pellicle films have brittle failure characteristics, meaning that their strength and lifetime are strongly dependent on the presence and size of as-produced imperfections such as micro-cracks and holes.

[0038] The composite and at least partially crystalline composition of existing composite pellicle film materials may intrinsically possess a large number of micro-cracks (e.g. grooves at crystal junctions) and / or micro-holes, limiting the strength and lifetime of the pellicle film. The micro-cracks and / or micro-holes can serve as crack initiation sites for brittle failure through crack propagation. Inaddition, existing pellicle films may be very thin (e.g. 5-20nm in thickness) in order to increase EUV transmission, further compounding susceptibility to pellicle failure.

[0039] Under stresses from transport, handling and operation, cracks can easily propagate within the film. The propagating cracks may also merge with each other, forming a network of cracks, leading to premature breakage of the pellicle film.

[0040] At present, no preventative measures have been devised to arrest or suppress crack propagation in composite EUV pellicles.

[0041] In the following description, reference shall be made to figures in which there are multiple instances of a substantially similar components. For the sake of clarity, these substantially similar components will be labelled only once. In addition, reference will be made to axes shown in the figures - for reference, the z-direction substantially corresponds to a normal direction of a pellicle film plane.

[0042] It has been found that cracks predominantly propagate in association with the MozSi ; phase of molybdenum silicon nitride-based pellicle films. Crack growth has been found to occur both within and between MosSiz crystals (also referred to as grains). In addition, crack growth has been observed along MoSiz / MosSiz phase boundaries. In contrast, cracks very rarely or never propagate in association with the MoSiz phase of molybdenum silicon nitride-based pellicle films. It can be inferred that the MoSiz phase is more ductile than MosSiz-

[0043] Figure 3 schematically illustrates a lateral cross-section of the microstructure of pellicle film 19 according to an embodiment of the present disclosure. The pellicle film 19 comprises MoSiz crystals 20 and MosSiz crystals 22 dispersed in an amorphous matrix 24 comprising silicon nitride. The pellicle film 19 comprises a volume of MoSiz crystals and MosSiz crystals. 70% or more of the total volume of MoSiz crystals and MosSiz crystals in the film is composed of MoSiz crystals. 30% or less of the total volume of MoSiz crystals and MosSiz crystals in the film MosSiz crystals total volume of MoSiz crystals and MozSi ; in the film. It will be appreciated that there may be one or more capping layers present.

[0044] In some embodiments, the average grain size of MozSi ; may be less than about 10 nm. Advantageously, reducing the average grain size improves the fracture toughness of brittle materials. The average grain size of the MoSiz phase may be from about 50 nm to about 100 nm.

[0045] The higher volume fraction of MoSiz crystals promotes crack blunting and thus supression or arrest of crack propagation, particularly in the lateral x-y plane of the film. As shown in Figure 3, crack 26 propagates through the MozSi ; phase 22, before being blunted and stopped at the MoSiz phase 20. Similarly, any incipient cracks in the pellicle film 19 are likely to be prevented from further propagation by the predominant MoSiz phase 20 before significantly undermining the pellicle film to the point of failure.

[0046] Furthermore, the predominance of the MoSiz reduces the frequency and extent of MozSis phase and grain boundaries, reducing potential crack initiation and / or propagation sites.

[0047] The crack resistance of a pellicle film can be evaluated by means of the Irwin model:whereKcis the material fracture toughness, c is the material yield strength, and rpis the crack tip plastic zone length.

[0048] The larger the crack tip plastic zone and thus the larger the value of rp, the greater the resistance of a material to cracking. Through estimation based on values for the bulk materials, it can be shown that, the value of rpfor an existing MosSis-dominant films is around 1 pm. The estimated value of rpfor a MoSi 2-dominant films is around 24 pm. MoSiz-dominant films have a much greater crack resistance than existing MosSiz-dominant films.

[0049] The toughness and lifetime of the above-described pellicle film is increased relative to known molybdenum silicon nitride -based pellicle films, without compromising the EUV transmissivity and emissivity of the film. Increased toughness and lifetime contribute to greater pellicle film reliability.

[0050] In use, cracks may also propagate through the pellicle in the z-direction.

[0051] Figure 4a shows a transverse cross-section of the microstructure of a pellicle film 30 according to another embodiment. The pellicle film 19 comprises MoSiz crystals 20 and MosSiz crystals 22 dispersed in an amorphous matrix 24 comprising silicon nitride. The pellicle film is characterized by a multi-layered microstructure.

[0052] The MoSiz crystals 20 and MosSiz crystals 22 lie in a first set of substantially segregated layers 32 and a second set of substantially segregated layers 34, respectively.

[0053] The crystals of MoSiz are elongate. The elongate MoSiz crystals have major axes. The major axes of the elongate MoSiz crystals substantially align with the plane of the pellicle film (which corresponding with the x-y lateral plane). In some embodiments the elongate MoSiz crystals may have an aspect ratio of at least 3.

[0054] Figure 4b shows a transverse cross-section of the microstructure of a pellicle film 40 according to an alternative embodiment of the present disclosure. As for the above-described embodiments, the pellicle film 40 comprises MoSiz crystals 20 and MosSiz crystals 22 dispersed in an amorphous matrix 24 comprising silicon nitride. The pellicle film 40 further comprises an interlayer 42. The MoSiz crystals 20 may or may not be elongate.

[0055] The interlayer may be selected from one or more of zirconium oxide, carbon, or yttrium silicon oxide. The composition of the interlayer may comprise materials exhibiting suppression of crack propagation (e.g. yttrium silicon oxide).

[0056] The multi-layered microstructures described with reference to the Figures 4a and 4b avoid singular grains spanning the pellicle film thickness. In particular, MosSiz grains spanning the pellicle film thickness provide a direct path for crack propagation through the pellicle film. By providing elongate MoSiz crystals 20 or an interlayer 42, the propagation of initiated cracks in the z-axis is suppressed partway through the pellicle film thickness by an interposed layer of more ductile material. The brittle MosSiz phase is isolated by adjacent layers of more ductile material (e.g. elongate MoSiz 20 or interlayer 42). In addition, the multi-layered structures may exhibit crack deflection, further increasing the toughness and lifetime of the composite pellicle film. In general, the microstructures described with reference to the Figures 4a and 4b impart a degree of plastic behaviour to the pellicle film.

[0057] In an example, where the microstructure at the crack tip is zirconium oxide-dominated, the value of rpestimated (see equation (1) above) to be around 35 pm, indicating a much greater crack resistance (particularly in the z-axis) relative to existing MosSiz-dominant films.

[0058] The multi-layered microstructures described with reference to Figures 4a and 4b also introduce large phase boundary areas along the (x-y) planar direction. The large phase boundary areas exhibit shear deformation by relative sliding movement of the layers. This deformation mechanism can dissipate strain energy from tensile stresses without fracturing, improving the pellicle film reliability.

[0059] In the microstructure described with reference to Figure 4b, the interlayer 42 can act as a more ductile layer bearing a greater proportion of tensile loads, reducing the stress concentration in the brittle Mo Si ; phase. In addition, the relative homogeneity of the interlayer 42 can contribute to a more uniform lateral distribution of tensile stress.

[0060] Whilst the embodiments described with reference to Figures 3 - 4b are described separately, the microstructural features described may be complementary in combination. For example, some embodiments may combine the MoSiz-dominant microstructure of pellicle film 19 (Figure 3) with the multi-layered microstructure of either pellicle film 30 or 40 (described with reference to Figures 4a and 4b, respectively. The previously-described combination embodiments, advantageously comprise microstructural features for suppressing crack propagation both laterally, in the x-y plane, and vertically, in the z-direction.

[0061] In some embodiments, the above-described pellicle films may further comprise one or more capping layers, Capping layers may provide additional thermo-chemical stability to a pellicle film.

[0062] Pellicle films with the above-described microstructures may be manufactured by a method comprising deposition of material layers in a sputtering physical vapour deposition process. Parameters of the method may be adjusted to suit manufacture of pellicle films with particular microstructural characteristics. The method may include varying one or more of a molybdenum content of a target, a nitrogen concentration of a sputtering gas stream and an annealing temperature.

[0063] In an alternative, other deposition methods may be used to manufacture pellicle films having one or more of the above-described microstructures. For example, alternative manufacturingmethods may comprise one or more of the following: pulsed laser deposition, molecular beam epitaxy, atomic layer deposition, chemical vapor deposition or other deposition methods.

[0064] Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquidcrystal displays (LCDs), thin-film magnetic heads, etc.

[0065] Although specific reference may be made in this text to embodiments of the invention in the context of a lithographic apparatus, embodiments of the invention may be used in other apparatus. Embodiments of the invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes an object such as a wafer (or other substrate) or mask (or other patterning device). These apparatus may be generally referred to as lithographic tools or exposure apparatus. Such a lithographic tool may use vacuum conditions or ambient (non- vacuum) conditions.

[0066] While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The descriptions above are intended to be illustrative, not limiting. Thus it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the claims set out below.

Claims

CLAIMS1. A pellicle film for an exposure apparatus, wherein the pellicle film comprises MoSiz and Mo Si ; crystals dispersed in an amorphous matrix, wherein the pellicle film is characterized by one or both of: i) 70% or more MoSiz crystals and 30% or less MozSi ; crystals as a volume percentage of a total volume of MoSiz crystals and MozSi ; crystals in the film; and ii) a multi-layered microstructure.

2. The pellicle film according to claim 1 wherein at least some of the MoSiz crystals are elongate.

3. The pellicle film according to claim 2 wherein major axes of the elongate MoSiz crystals substantially align with a major plane of the pellicle film.

4. The pellicle film according to claim 2 or claim 3 wherein the elongate MoSiz crystals have an aspect ratio of at least 3.

5. The pellicle film according to any preceding claim wherein the pellicle film further comprises an interlayer, optionally wherein the interlayer is selected from one or more of zirconium oxide, carbon, or yttrium silicon oxide.6 The pellicle film according to any preceding claim wherein the average grain size of MoSiz phase is from about 50 nm to about 100 nm.

7. The pellicle film according to any preceding claim wherein the average grain size of MozSi ; is less than about 10 nm.

8. The pellicle film according to any preceding claim wherein the amorphous matrix comprises silicon nitride.

9. The pellicle film according to any preceding claim wherein the pellicle film has thickness from around 5 to about 20 nm.

10. A pellicle assembly for an exposure apparatus, such as a lithographic apparatus, the pellicle assembly including a pellicle film according to any preceding claim and a support frame for supporting the pellicle film.

11. An exposure apparatus comprising the pellicle or pellicle film according to any preceding claim.

12. A method of manufacturing a pellicle film, wherein the method comprises deposition of material layers to form a pellicle film characterized by one or both of: i) 70% or more MoSiz crystals and 30 % or less Mo Si ; crystals as a volume percentage of a total volume of MoSiz crystals and Mo Si ; crystals in the film; and ii) a multi-layered microstructure.

13. The method according to claim 12 wherein the method includes varying one or more of a molybdenum content of a target, a nitrogen concentration of a sputtering gas stream and an annealing temperature.

14. The method according to claim 12 or 13 wherein the method comprises depositing an interlayer, optionally wherein the one or more layers are selected from one or more of zirconium oxide, carbon or yttrium silicon oxide.

15. The use of a pellicle film according to any of claims 1 to 9, a pellicle according to claim 10, an exposure apparatus according to claim 11, or a method according to any of claims 12 to 14 in an EUV exposure method or apparatus.

Images