Pellicle for use in lithographic apparatus and method for forming same

Abstract

A pellicle for use in a lithographic apparatus, the pellicle comprising: a septum having a first portion and a second portion; and a protective portion located at the second portion on at least one side of the diaphragm. A method for forming a pellicle for use in a lithographic apparatus, the method comprising: providing a septum having a first portion and a second portion; and providing a protective portion at the second portion on at least one side of the diaphragm.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to EP application 22195223.7 filed on September 12, 2022 and US application 63 / 451,809 filed on March 13, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present specification relates to a pellicle for use in a lithographic apparatus and an associated method for forming such a pellicle. The present specification also relates to a lithographic apparatus comprising a pellicle arranged in a path of a radiation beam of the lithographic apparatus for forming an image on a substrate. Background Art

[0004] A lithographic apparatus is a machine configured to apply a desired pattern to a substrate. For example, a lithographic apparatus may be used to manufacture integrated circuits (ICs). For example, a lithographic apparatus may project a pattern at a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) disposed on a substrate.

[0005] 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 that can be formed on the substrate. Compared to a lithographic apparatus using radiation having a wavelength of, for example, 193 nm, a lithographic apparatus using extreme ultraviolet (EUV) radiation (having a wavelength in the range of 4 nm to 20 nm, such as 6.7 nm or 13.5 nm) may be used to form smaller features on a substrate.

[0006] A patterning device (e.g., a mask) is used to impart a pattern to a radiation beam in a lithographic apparatus. The patterning device may be protected from particle contamination by a pellicle. The pellicle may be supported by a pellicle frame.

[0007] A typical pellicle is a diaphragm that is positioned away from the patterning device and outside the focal plane of the lithographic apparatus in use. Because the pellicle is outside the focal plane of the lithographic apparatus, contaminant particles that fall on the pellicle are out of focus in the lithographic apparatus. Therefore, the image of the contaminant particles is not projected onto the substrate. If the pellicle is not present, contaminant particles that fall on the patterning device may be projected onto the substrate and may introduce defects into the projected pattern.

[0008] It may be desirable to provide an apparatus and / or method that obviates or mitigates one or more problems associated with the prior art. Summary of the invention

[0009] According to a first aspect, a pellicle for use in a lithographic apparatus is provided, the pellicle comprising: a membrane comprising a first portion and a second portion; and a protective portion, the protective portion being located at the second portion on at least one side of the membrane. For example, the pellicle used in the lithographic apparatus is a pellicle comprising: a membrane comprising carbon nanotubes, the membrane comprising a first portion and a second portion; and a protective portion, the protective portion being located at the second portion on at least one side of the membrane, wherein the protective portion comprises a material suitable for protecting the second portion of the membrane from etching.

[0010] The membrane may for example comprise a layer having the same type of carbon nanotubes in both the first and second portions and wherein the material of the protective portion covering the second portion of the membrane is transparent to at least a fraction of the EUV imaging radiation received by the first portion.

[0011] The advantage is that the service life of the pellicle can be increased without affecting the performance of the lithography equipment.

[0012] The protective portion may be located only at or on the second portion. The protective portion may not be located at or on the first portion. The extent to which the protective portion is located at or on the first portion may be less than the extent to which it is located at or on the second portion. The protective portion may be located directly on, in contact with, and / or supported by the diaphragm. The protective portion may be, for example, a layer that is thick enough to chemically protect the second portion from the (e.g., plasma) etching environment, while the layer is still thin enough that the second portion remains substantially transmissive to EUV radiation. The protective portion may be a layer of material deposited in direct contact with the diaphragm, or the protective portion may be thicker because the extent to which the protective portion is etched away during the diaphragm manufacturing process is less than the extent to which the first portion is etched away. In other words, if the first and second portions are the same, the difference between the first and second portions is that the second portion of the diaphragm is thicker than the first portion. Alternatively, the material of the protective portion may be different from the material of the second portion of the diaphragm and / or the entire diaphragm. The material of the protective portion is generally referred to as "cap material" hereinafter. For example, if the diaphragm core is made of carbon nanotubes with certain properties (size, etc.), the cover material forming the protective portion may include a different material, or carbon nanotubes with different properties than the diaphragm. However, the cover material may also have the same carbon nanotubes as the diaphragm (core) as long as the second portion is thicker than the first portion (where the protective portion is a carbon nanotube layer with a thickness equal to the difference in thickness between the first and second portions).

[0013] Alternatively, the protective portion may be a separate element separated from the diaphragm (e.g., by a gap). The separate element may be, for example, a plate, a rigid diaphragm, or a protruding element. In this case, the protective portion may still be considered to be adjacent to / on at least one side of the diaphragm.

[0014] At least one side of the diaphragm may be the front side of the diaphragm. That is, the side on which EUV radiation (EUV radiation beam B) is incident from the radiation source SO and / or the illumination system. The front side may be opposite to the back side (second side), i.e. the side facing the patterning device in use. The front side may be opposite to the side attached to the pellicle frame.

[0015] In use, the second portion may not receive EUV imaging radiation or may receive only a small portion of the EUV imaging radiation received by the first portion. However, for clarity, the second portion is capable of transmitting EUV imaging radiation, so that in the event that the second portion, in use, will receive EUV imaging radiation or a small portion of the EUV imaging radiation received by the first portion, at least a portion of the received EUV radiation is transmitted through the membrane.

[0016] The second portion may be an unexposed area, such as an area that is etched faster during exposure. Such a higher etch rate of the second unexposed area may be caused by being at a lower temperature than the exposed area if the carbon-based film has a higher etch rate.

[0017] The first portion may substantially correspond to a predetermined exposure area of ​​a patterning device for use with the pellicle.

[0018] The first portion may be substantially the same size as a predetermined exposure area of ​​the patterning device.

[0019] The second portion may be located at a periphery of the diaphragm.

[0020] The pellicle may include a border at the periphery of the diaphragm, wherein the second portion may coincide with the border. However, it will be understood that the border is generally not part of the second portion and that the border is not considered a protective region herein. The border generally does not transmit EUV radiation and the function of the border is only to support the diaphragm at the periphery to prevent bending or breaking when in contact with the frame. Only in special cases when the border is so thin as to transmit at least 10% of the EUV radiation and can be irradiated with exposure radiation, the border may be considered a protective region. For example, the pellicle includes a border at the periphery of the diaphragm, wherein the second portion coincides with the border in size and the border is arranged on the side of the diaphragm opposite to the protective portion.

[0021] The protective portion may include a material suitable for protecting the second portion of the thin membrane from hydrogen etching.

[0022] The protective portion may be located on at least one of: a first side and an opposing second side of the diaphragm; and an edge of the diaphragm.

[0023] The protective portion may be located on only one side of the diaphragm (eg, the front side of the diaphragm).

[0024] The first side of the diaphragm may be the front side of the diaphragm. The second side of the diaphragm may be the back side of the diaphragm.

[0025] The protective portion may include a material covering the second portion (also referred to as a cover material).

[0026] The cover material may include at least one of the following: carbon nanotubes, graphene, amorphous carbon, (low melting point metal), molybdenum (Mo), yttrium (Y), yttrium oxide (Y a O b )、Alumina(Al 2 O 3 )(AlO 2 )、HfO 2 )、ZrO 2 ), ruthenium (Ru), platinum (Pt), gold (Au), zirconium nitride (ZrN), aluminum (Al), zirconium (Zr), silicon (Si), silicon carbide (SiC), silicon oxide (SiO a ), boron (B), boron carbide (B 4 C), boron nitride (BN), titanium (Ti) and titanium nitride (TiN).

[0027] The diaphragm may include a protective portion, and the protective portion may include the same material as the first portion and the second portion.

[0028] The pellicle may include a pellicle frame, and the protective portion may include a shield, wherein the shield may be supported by the pellicle frame.

[0029] The shield may be separated from the membrane by a gap, preferably wherein the gap is less than 1000 μm or less than 2000 μm.

[0030] The shield may be at least one of: substantially transparent to heater radiation, substantially transparent to IR radiation, substantially transparent to DUV radiation, and inert in the plasma.

[0031] The shield may include at least one of the following: aluminum oxide (Al 2 O 3 ), sapphire, aluminum oxide (Al 2 O 3 ) coated glass, and sapphire coated glass.

[0032] The protective portion may include a plurality of shields: a first shield located on a first side of the diaphragm, a second shield located on an opposite second side of the diaphragm.

[0033] The first portion may substantially correspond to an extended area that is larger than a predetermined exposure area of ​​a patterning device used with the pellicle.

[0034] The extended region may extend outwardly from a predetermined exposure region of the pattern forming device to a predetermined distance.

[0035] The extended region may extend outward from the predetermined exposure region of the pattern forming device by at least one of 1000 μm, a distance in the range of 1000 μm to 2000 μm, and a distance in the range of 1000 μm to 4000 μm.

[0036] The second portion may extend inwardly to a predetermined distance relative to an inner edge of the pellicle frame and / or a border at a periphery of the diaphragm.

[0037] The second portion may extend inwardly relative to the inner edge and / or border of the pellicle frame by at least 1300 μm, at least 1500 μm, at least 2300 μm, a distance in the range of 1300 μm to 2300 μm.

[0038] The separator may include a carbon-based material, such as carbon nanotubes.

[0039] According to a second aspect, there is provided a lithographic apparatus operable to form an image of a patterning device on a substrate using a radiation beam, the lithographic apparatus comprising a pellicle arranged in a path of the radiation beam, the pellicle being as described above.

[0040] According to a third aspect, there is provided a method for forming a pellicle for use in a lithographic apparatus, the method comprising: providing a diaphragm comprising a first portion and a second portion, providing a protective portion at the second portion on at least one side of the diaphragm. For example, the method for forming a pellicle for use in a lithographic apparatus comprises: providing a diaphragm comprising carbon nanotubes, the diaphragm comprising a first portion and a second portion, providing a protective portion at the second portion on at least one side of the diaphragm, wherein the protective portion comprises a material suitable for protecting the second portion of the thin diaphragm from etching.

[0041] The method may also include providing the protective portion using an additive or subtractive method.

[0042] The method may further include providing the protective portion using an additive process, wherein the protective portion may include a capping material; and depositing the capping material on the second portion to cover the second portion.

[0043] The method may further include masking the first portion using a masking element.

[0044] The masking element may substantially correspond to a predetermined exposure area of ​​a patterning device for use with the pellicle.

[0045] The method may further include depositing the cap material using at least one of: thermal evaporation, electron beam evaporation, electron beam deposition, pulsed laser deposition, atomic layer deposition, and remote plasma sputtering.

[0046] The method may further include providing the protective portion using a subtractive process, wherein the protective portion may include a capping material; applying the capping material to the first portion and the second portion, and removing the capping material from the first portion.

[0047] The method may also include removing the cap material from the first portion using at least one of: laser annealing, laser ablation, reactive ion etching, and lift-off.

[0048] The cap material may be a volatile material or a thermally unstable material that is desorbed by EUV radiation.

[0049] The method may also include using a subtractive method to provide the protective portion, the subtractive method comprising: providing a diaphragm having a thickness, and partially removing the first portion to reduce the thickness of the first portion, wherein the diaphragm may include the protective portion, and the protective portion may include the same material as the first portion and the second portion.

[0050] The method may also include etching the first portion in a hydrogen plasma.

[0051] The method may further include providing a protective portion on at least one of: a first side and an opposing second side of the septum; and an edge of the septum.

[0052] The method may further include providing the first portion to substantially correspond to a predetermined exposure area of ​​a patterning device for use with the pellicle.

[0053] The method may further include providing a protective portion during at least one of fabrication of the pellicle, fabrication of the patterning device, and fabrication of the substrate.

[0054] The method may further include providing a pellicle frame, wherein the protective portion may include a shield and the pellicle frame may support the shield.

[0055] The method may also include separating the shield from the diaphragm by a gap.

[0056] The method may further include providing a plurality of shields, a first shield positioned on a first side of the diaphragm, and a second shield positioned on an opposing second side of the diaphragm.

[0057] The method may further include providing the first portion to substantially correspond to an extended area that is larger than a predetermined exposure area of ​​a patterning device for use with the pellicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

[0059] - Figure 1 A lithography system including a lithography apparatus and a radiation source is depicted;

[0060] - Figure 2 schematically depicts a cross-sectional view of a pellicle and a patterning device according to an embodiment of the present disclosure;

[0061] - Figure 3 Schematically depicts Figure 2 Plan view of the membrane;

[0062] - Figure 4 The expected etch rate of hydrogen etching of carbon as a function of temperature is shown for four different ion energies: 5 eV, 10 eV, 20 eV and 30 eV and for a hydrogen ion flux of 1.5·1019 m-2·s-1; Figure 4 The function relationship of sp3 carbon concentration and temperature is also shown;

[0063] - Figure 5 is a schematic diagram of a method for forming a pellicle according to an embodiment of the present disclosure; and

[0064] - Figure 6 A cross-sectional view of a pellicle and a patterning device according to another embodiment of the present disclosure is schematically depicted. DETAILED DESCRIPTION

[0065] Figure 1 A lithography system is shown including a pellicle 15. The lithography system comprises a radiation source SO and a lithography 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 lithography apparatus LA. The lithography 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.

[0066] The illumination system IL is configured to condition the EUV radiation beam B before it is incident on the pattern forming device MA held by the support structure MT. In addition, the illumination system IL may include a faceted field mirror device 10 and a faceted pupil mirror device 11. The faceted field mirror device 10 and the faceted pupil mirror device 11 together provide an 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 the faceted pupil mirror device 11. The pattern forming device MA is protected by a pellicle 15. The pellicle 15 includes a diaphragm 19 fixed in place by a pellicle frame 17. The diaphragm 19 and the pellicle frame 17 together form the pellicle 15.

[0067] After being so conditioned, the EUV radiation beam B interacts with the pattern forming 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 a substrate W. For this purpose, the projection system PS may include a plurality of mirrors 13, 14, which are configured to project the patterned EUV radiation beam B' onto a substrate W, which is held by a substrate table WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B', thereby forming an image having features that are smaller than corresponding features on the pattern forming device MA. For example, a reduction factor equal to 4 or 8 may be applied. Although the projection system PS is Figure 1 1. Although illustrated in FIG. 1 as having only two mirrors 13, 14, the projection system PS may comprise a different number of mirrors (eg six or eight mirrors).

[0068] The substrate W may include a pre-formed pattern. In this case, the lithographic apparatus LA aligns the image formed by the patterned EUV radiation beam B′ with the pattern previously formed on the substrate W.

[0069] A relative vacuum, ie a small amount of gas (eg 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.

[0070] Figure 1 The radiation source SO shown in FIG. 1 is of a type which may be referred to as a laser produced plasma (LPP) source, for example. It may include, for example, CO 2The laser system 1 of the laser is arranged to deposit energy via a laser beam 2 into a fuel, such as tin (Sn) provided by, for example, a fuel emitter 3. Although tin is mentioned in the following description, any suitable fuel may be used. The fuel may, for example, be in liquid form and may, for example, be a metal or an alloy. The fuel emitter 3 may include a nozzle configured to direct tin, for example in the form of droplets, along a trajectory toward a plasma formation region 4. The laser beam 2 is incident on the tin at the plasma formation region 4. The deposition of laser energy into the tin generates a tin plasma 7 at the plasma formation region 4. During de-excitation and recombination of electrons with ions of the plasma, radiation including EUV radiation is emitted from the plasma 7.

[0071] EUV radiation from the plasma is collected and focused by a collector 5. The collector 5 includes, for example, a near normal incidence radiation collector 5 (sometimes more generally referred to as a normal incidence radiation collector). The collector 5 may have a multilayer mirror structure arranged to reflect EUV radiation (e.g., EUV radiation having a desired wavelength such as 13.5 nm). The collector 5 may have an elliptical configuration including two foci. As discussed below, a first of the foci may be at the plasma formation region 4, and a second of the foci may be at the intermediate focus 6.

[0072] The laser system 1 may be spatially separated from the radiation source SO. In this case, the laser beam 2 may be delivered from the laser system 1 to the radiation source SO with the aid of a beam delivery system (not shown) comprising, for example, suitable directional mirrors and / or beam expanders, and / or other optical devices. The laser system 1, the radiation source SO and the beam delivery system may be considered together as a radiation system.

[0073] The radiation reflected by the collector 5 forms an EUV radiation beam B. The EUV radiation beam B is focused at an intermediate focus 6 to form an image at the intermediate focus 6 of a plasma present at the plasma formation region 4. The image at the intermediate focus 6 serves as a virtual radiation source for the illumination system IL. The radiation source SO is arranged so that the intermediate focus 6 is located at or near an opening 8 in an enclosure 9 of the radiation source SO.

[0074] although Figure 1 The radiation source SO is depicted as a laser produced plasma (LPP) source, but any suitable source such as a discharge produced plasma (DPP) source or a free electron laser (FEL) may be used to generate EUV radiation.

[0075] As briefly described above, the pellicle 15 comprises a diaphragm 19 disposed adjacent the patterning device MA. The diaphragm 19 is disposed in the path of the radiation beam B such that the radiation beam B passes through the diaphragm 19 both when it approaches the patterning device MA from the illumination system IL and when it is reflected by the patterning device MA towards the projection system PS. The diaphragm (or film) 19 is substantially transparent for EUV radiation (although the diaphragm 19 will absorb a small amount of EUV radiation). An EUV transparent diaphragm or a film that is substantially transparent for EUV radiation means in this context that the diaphragm 19 transmits at least 65% of the EUV radiation, preferably at least 80% and more preferably at least 90% of the EUV radiation. The diaphragm 19 serves to protect the patterning device MA from particle contamination. The diaphragm 19 may be referred to herein as an EUV transparent diaphragm.

[0076] Although 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 membrane 19, the particles may be deposited onto the patterning device MA. The particles on the patterning device MA may adversely affect the pattern imparted to the radiation beam B and thus affect the pattern transferred to the substrate W. The membrane 19 provides a barrier between the patterning device MA and the environment in the lithographic apparatus LA so as to prevent particles from being deposited on the patterning device MA.

[0077] In use, the diaphragm 19 is positioned at a distance from the patterning device MA that is sufficient so that any particles incident on the surface of the diaphragm 19 are not in the focal plane of the radiation beam B. This spacing between the diaphragm 19 and the patterning device MA serves to reduce the extent to which any particles on the surface of the diaphragm 19 impart a pattern to the radiation beam B. It will be appreciated that where a particle is present in the radiation beam B but at a position that is not in the focal plane of the radiation beam B (i.e. not at the surface of the patterning device MA), then any image of the particle will not be focused at the surface of the substrate W. In the absence of other considerations, it may be desirable to position the diaphragm 19 a considerable distance away from the patterning device MA. However, in practice, the space available in the lithographic apparatus LA for accommodating the pellicle 15 is limited by the presence of other components. In some embodiments, the spacing between the diaphragm 19 and the patterning device MA may be, for example, approximately between 1 mm and 10 mm, for example between 1 mm and 5 mm, for example between 2 mm and 3 mm (e.g., approximately 2.5 mm), for example between 2 mm and 2.5 mm. In some embodiments, the spacing between the membrane 19 and the patterning device MA may be adjustable.

[0078] The pellicle 15 may include a border portion. The border portion of the pellicle 15 may be hollow and substantially rectangular, and the diaphragm 19 may be defined by the border portion. As is known in the art, one type of pellicle may be formed by depositing one or more thin layers of material on a substantially rectangular silicon substrate. During this stage of pellicle construction, the silicon substrate supports one or more thin layers. Once a layer having a desired thickness and composition or a target thickness and composition has been applied, the central portion of the silicon substrate is removed by etching (which may be referred to as reverse etching). The peripheral portion of the rectangular silicon substrate is not etched (or alternatively etched to a lesser extent than the central portion). The peripheral portion forms the border portion of the final pellicle, and the one or more thin layers form the diaphragm of the pellicle (the diaphragm is surrounded by the border portion). The border portion of the pellicle may be formed by silicon.

[0079] Some embodiments of the present disclosure relate to a new type of pellicle and a method of forming the pellicle.

[0080] The pellicle 15 (e.g., including the border) may require some support from a more rigid pellicle frame 17. The pellicle frame 17 can provide two functions. First, the pellicle frame 17 can support and tension the diaphragm 19. Second, the pellicle frame 17 can facilitate the connection of the pellicle 15 to the pattern forming device (reticle or mask) MA. In one known arrangement, the pellicle frame 17 can include a main, generally rectangular body portion that is glued to the border portion of the pellicle 15 and a titanium attachment mechanism that is glued to one side of the body. Intermediate fixing members (referred to as studs) are fixed to the pattern forming device (reticle) MA. The intermediate fixing members (studs) on the pattern forming device (reticle) MA can engage (e.g., releasably engage) with the attachment members of the pellicle frame 17.

[0081] Figure 2 yes Figure 1 A more detailed cross-sectional view of the membrane 15 and the pattern forming device MA is shown in FIG. The membrane 15 includes a membrane frame 17 (hereinafter referred to as a frame) and a membrane 19. Although Figure 119, but the diaphragm 15 includes a diaphragm border 20. The border 20 is optionally formed integrally with the diaphragm 19, included in the diaphragm, or physically separated from the diaphragm. The border 20 can be significantly thicker than the main part of the diaphragm 19 and can be located around the outer perimeter (periphery) of the diaphragm 19. It is this border 20 that is attached to the frame 17. The frame 17 supports the diaphragm 15 around the peripheral portion of the diaphragm 19 via the border 20. The border 20 can be glued to the frame 17 or can be attached in another way. In an embodiment, the diaphragm 19 and the border 20 are made together (i.e., at the same time). In some embodiments, the border 20 can be formed integrally with the frame 17. It will be understood that in other embodiments, the diaphragm 15 may not include a border, i.e., the diaphragm 19 can be formed directly on the frame 17.

[0082] The frame 17 may include an engagement mechanism 22 configured to allow the frame 17 to be detachably attached to the patterning device MA (i.e., to allow the frame 17 to be attached to and detached from the patterning device MA). The engagement mechanism 22 is configured to engage with an attachment member 24 provided on the patterning device MA. For example, the attachment member 24 may be a protrusion or a stud extending from the patterning device MA. The engagement mechanism 22 may, for example, include a locking member (not shown) that engages with the attachment member 24 and secures the frame 17 to the patterning device MA.

[0083] A plurality of engagement mechanisms 22 and associated attachment members 24 may be provided. The engagement mechanisms 22 may be distributed around the frame 17. The associated attachment members may be distributed around the perimeter of the patterning device MA.

[0084] The patterning device MA has a patterned surface 25. Contaminant particles 26 are schematically shown. The contaminant particles 26 are incident on and held by the diaphragm 19. The diaphragm 19 holds the contaminant particles 26 sufficiently far from the patterned surface 21 of the mask MA so that the contaminant particles 26 are not imaged onto the substrate by the lithographic apparatus LA. The pellicle 15 may allow a mask pattern to be provided (on the patterning device MA) that is protected from contamination by the pellicle 15 so that a pattern produced using the mask remains substantially defect-free during use.

[0085] The pellicle 15 may be constructed by depositing the membrane 19 directly on top of the substrate to provide the border 20. After the membrane 19 of the pellicle 15 is deposited, the substrate may be selectively etched back to remove the central portion of the substrate and leave only the outer perimeter to form the border 20 supporting the membrane 19. Alternatively, the material for the border 20 may be deposited. This may be preferable as it avoids the challenges and stresses of selective removal.

[0086] The pellicle 15 may be suitable for use adjacent to a mask MA within an EUV lithography apparatus LA. In use, such a (reflective) MA is illuminated by EUV radiation, for example from an illumination system IL. It will be appreciated that the mask MA is configured to impart a pattern to the radiation beam received from the illumination system IL in its cross-section to form a patterned radiation beam. The projection system collects the (reflected) patterned radiation beam and forms a (diffraction-limited) image of the mask MA on a substrate (e.g., a silicon wafer coated with resist). In general, any contaminants on the mask MA will alter the image formed on the substrate, resulting in printing errors.

[0087] In order to avoid particle contamination of the mask MA, a pellicle 15 is used to protect the mask MA. As described, the pellicle 15 is arranged in front of the mask MA and prevents particles 26 from falling on the mask MA. The diaphragm 19 of the pellicle 15 is arranged so that the diaphragm 19 will not be clearly imaged by the projection system, and therefore the particles on the diaphragm 19 will not interfere with the imaging process. It is desirable that the diaphragm 19 is strong enough so that the diaphragm 19 prevents the particles 26 from being incident on the mask MA, which would cause unacceptable printing errors, but the diaphragm 19 is as thin as possible to reduce the absorption of EUV radiation by the diaphragm 19.

[0088] The diaphragm 15 comprises a protective portion 28. In this embodiment, the protective portion 28 is provided at the periphery of the diaphragm 19 and on a first side 30A of the diaphragm 19. The first side 30A may be considered as the front side. That is, the side on which EUV radiation (EUV radiation beam B) is incident from the radiation source SO and / or the illumination system IL. The first side 30A is opposite to the side of the diaphragm 19 that faces the pattern forming device MA in use. The first side 30A is opposite to the side of the diaphragm 19 that is attached to the diaphragm frame 17. The border 20 is provided at the periphery of the diaphragm 19 and on a second side 30B of the diaphragm. The second side 30B may be considered as the rear side. In use, the second side 30B faces the pattern forming device MA. The second side 30B is attached to the diaphragm frame 17 (i.e. via the border 20). In other embodiments, the protective portion may alternatively or additionally be provided on the rear side of the diaphragm. For example, both sides of the diaphragm (the front [first] side and the rear [second] side) may have a protective portion on a portion of its surface. Furthermore, alternatively or additionally, the protective portion may be disposed on an edge 30C of the membrane (i.e., an edge extending in the z-direction). Additionally, in embodiments (e.g., with a CNT membrane), the protective portion may be conformal (i.e., coated around the CNT tubes) or interstitial (i.e., within an internal space in the membrane). In general, the protective portion may be disposed on any portion of the membrane that may need protection (e.g., from etching). In embodiments, a protective portion located on the front side of the membrane may cover a different area than a protective portion located on the back side of the membrane. A protective portion located on the back side of the membrane may also cover a border.

[0089] The pattern forming device MA includes an exposure area 32 and a non-exposure area 34 (as delimited by dashed lines 35). That is, during imaging, the exposure area 32 will receive EUV radiation, while the non-exposure area 34 will not receive EUV radiation. The exposure area 32 has an area (in the xy plane) that forms at least a portion of the patterned surface 25. The exposure area 32 can be predetermined based on a selected or desired specific field size. The exposure area 32 can be a selected mask exposure field. The exposure area 32 can be referred to as a mask imaging field. The exposure area 32 can be continuous, that is, a single area. The exposure area 32 can include multiple tube cores (not shown) or a single tube core with intervals for cutting or measurement. The tube core can be clustered. If it is considered that there are exposure areas for separate tube cores, then the exposure area can be continuous.

[0090] The membrane 19 includes a first portion 36 and a second portion 38 (as delimited by dashed line 39). The first portion 36 has a first area and the second portion 38 has a second area (i.e., in the xy plane). In an embodiment, the first portion 36 corresponds to a predetermined exposure area 32 of the pattern forming device MA. That is, the first portion 36 is substantially the same size as the exposure area 32 (i.e., has the same area). Therefore, similarly, the second portion 38 extends inwardly (toward the center in the x direction) to the same extent as the non-exposure area 34. It will be appreciated that the non-exposure area 34 can extend further outwardly (away from the center in the x direction) than the second portion 38, because the pattern forming device MA can be larger than the membrane 19 in the x direction.

[0091] It will be appreciated that the first portion 36 may also be considered an exposed area, and the second portion 38 may also be considered an unexposed area, because only the first portion will receive EUV radiation during imaging. However, in some embodiments, the difference between the first portion 36 and the second portion 38 may relate to the amount of EUV imaging radiation incident thereon. For example, the first portion 36 may receive the full (100%) maximum EUV power density, while the second portion 38 may receive only a fraction (e.g., 50%) of the maximum EUV power density. In general, the second portion 38 may receive EUV imaging radiation in use, but may receive only a fraction of the EUV imaging radiation (when compared to the amount received by the first portion 36).

[0092] As shown in the figure, the protective portion 28 is located at the second portion 38 on one side of the diaphragm 19 (i.e., the front side of the diaphragm 19). The protective portion 28 is not located at the first portion 36. In other words, the protective portion 28 is located only on the second portion 38 and not on the first portion 36. The protective portion 28 covers the second portion 38 and does not cover the first portion 36. It can be considered that the protective portion 28 only partially covers the diaphragm 19. In addition, the protective portion 28 covers only the non-imaging area (i.e., the area of ​​the second portion 38).

[0093] Figure 3 yes Figure 2 19. A plan (front) view of the membrane 15 is shown in FIG. 19. For clarity, the frame 17 and the patterning device MA are not included. The first portion 36 of the membrane 19 is substantially rectangular in the center of the membrane 19. The second portion 38 is substantially rectangular in the center of the membrane 19. Figure 2 28 and is located below the protective portion 28 and therefore cannot be seen in this view. However, it will be understood that the second portion 38 surrounds the first portion 36 on each side (relative to the xy plane). The protective portion 28 is shown as covering the second portion 38 (i.e., covering the same area or region). It will be understood that this is merely an example and other sizes and / or shapes of the first portion, second portion and / or protective portion may be provided.

[0094] As now discussed, Figure 2 and Figure 3 The membrane 15 shown in FIG. 1 is particularly advantageous.

[0095] A particularly advantageous carbon-based material for use as a pellicle membrane in an EUV lithography apparatus is a fabric or membrane formed of carbon nanotubes (CNTs). The CNT pellicle is a porous material and can therefore provide very high EUV transmittance (greater than 98%). In addition, the CNT pellicle also provides very good mechanical stability and can therefore be made with a smaller thickness while maintaining robustness against mechanical failure. However, low-pressure hydrogen is typically provided within the lithography apparatus, which forms a hydrogen plasma in the presence of EUV radiation (during exposure). The plasma is specifically present in the lithography apparatus LA to remove carbon deposited on the mirror surface in a vacuum. However, this may cause the CNT pellicle itself to be etched. It has been found that hydrogen ions and hydrogen radicals from the hydrogen plasma may etch the pellicle formed by the CNT, thereby limiting the potential service life of the pellicle and hindering the commercial implementation of the CNT pellicle.

[0096] In order to mitigate this etching of the CNT pellicle, it has been previously proposed to provide such CNT pellicles with a protective capping layer (coating). However, it is desirable to minimize the absorption of EUV radiation by the pellicle, and including a capping layer will increase EUV transmission losses. In addition, coatings on CNT membranes are temperature sensitive and will not survive (at least for the desired amount of time) in a high source power lithography apparatus LA. Furthermore, the difference between the refractive index of carbon and that of a suitable capping layer is typically greater than the difference between the refractive index of carbon and that of a vacuum. Therefore, such a capping layer will result in an increase in EUV flash (scattered light), which is undesirable because EUV flash degrades image quality. For CNT pellicles, or any carbon-based pellicle, the hydrogen plasma in the lithography apparatus LA will ultimately limit the service life.

[0097] The interaction of hydrogen ions with carbon materials is quantitatively described in the following two publications, the contents of which are incorporated herein by reference: (1) J. Roth, C. García-Rosales, "Analytic description of the chemical erosion of graphite by hydrogen ions," Nuclear Fusion 1996, 36 / 12, 1647-1659; and (2) J. Roth, C. García-Rosales, "Corrigendum-Analytic description of the chemical erosion of graphite by hydrogen ions," Nuclear Fusion 1997, 37, 897. This quantitative description of the interaction of hydrogen ions with carbon materials may be referred to as the Roth-García-Rosales (RGR) model. The RGR model can be used to predict the etch yield of carbon materials as a function of temperature for typical hydrogen ion energies encountered within a lithography apparatus (such as, for example, ion energies of 1 eV to 30 eV). Within an EUV lithography apparatus, a typical hydrogen ion flux incident on a pellicle may be approximately 1·1019 m-2·s-1. Within an EUV lithography apparatus, a typical hydrogen ion flux incident on a pellicle may be within multiple orders of magnitude of 1·1019 m-2·s-1 (e.g., from 1018 m-2·s-1 to 1020 m-2·s-1).

[0098] Figure 4 The expected etch rate of hydrogen etching of carbon as a function of temperature is shown for four different ion energies: 5 eV, 10 eV, 20 eV and 30 eV and for a hydrogen ion flux of 1.5·1019 m-2·s-1. The figure shows the sp3 carbon concentration as a function of temperature. It can be seen that for these typical ambient conditions in the lithographic apparatus LA, it is expected that for a film formed purely of CNTs, the hydrogen etch rate of the film will drop to a negligible level at a temperature of about 1050 K. However, the skilled person will appreciate that under different conditions, different minimum temperatures may be desirable.

[0099] The etching of carbon by hydrogen ions and radicals may be temperature dependent. Specifically, the carbon etching rate may be high at low and medium temperatures, but at sufficiently high temperatures, the carbon etching rate drops to a negligible degree or level. In addition, although the central portion of the diaphragm 19 in the EUV lithography scanner LA can reach a sufficiently high temperature so that hydrogen etching (at least part of the time) will be negligible, the periphery of the diaphragm 19 will generally remain below this temperature and will therefore be more susceptible to hydrogen etching. That is, the CNT diaphragm will be heated to a temperature that actually limits the hydrogen plasma etching rate. This essentially creates multiple partitions for the diaphragm 19, which will be referred to as the first portion 36 and the second portion 38. Although in an embodiment, the first portion 36 and the second portion 38 are relatively hot (exposed) zones and relatively cold (unexposed) zones, respectively, it will be understood that in other embodiments, the first portion 36 and the second portion 38 (different partitions) may be defined by other characteristics. In addition, different partitions (i.e., the first portion 36 and the second portion 38) may have different sizes and shapes as desired. In an embodiment, there may be a plurality of first portions 36 and / or a plurality of second portions 38. They may be separated, for example, two first portions 36 may be separated by a second portion 38, and vice versa.

[0100] To maximize the life and performance of the scanner, it is important to tailor each CNT membrane zone (or portion) to the scanner's purpose. The most highly exposed area of ​​the membrane (first portion 36) will be located over the reticle exposure field. The least exposed area (second portion 38) is located over the frame area and has less stringent optical requirements.

[0101] Advantageously, Figure 2 and Figure 3 The pellicle 15 shown in FIG. 1 provides an additional protective portion 28 on a second portion 38 of (the front side 30A of) the diaphragm 19 which: (a) is most at risk of being etched by hydrogen; and (b) does not receive EUV radiation in use. This allows the useful life of the pellicle 15 to be increased without affecting the performance of the lithographic apparatus LA.

[0102] In some embodiments, the protective portion 28 is provided on a portion of the membrane 19 which does not receive EUV radiation in use (during imaging [exposure]). The first portion 36 is exposed to EUV radiation (during imaging) and is therefore heated. The second portion 38 is not exposed to EUV radiation (during imaging) and is therefore not heated. Therefore, the second portion 38 needs to be protected to extend the service life. It will be appreciated that the second portion 38 does not necessarily need to be precisely aligned with the exposure area 32 of the patterning device MA, i.e., the second portion 38 may substantially correspond. For example, due to heat transfer from the EUV imaging radiation, a portion of the membrane 19 may be a distance (e.g., 0.25 mm to 2 mm) from a portion exposed to (all) EUV imaging radiation, which portion of the membrane 19 is not subject to etching (or at least is affected to an extent that is not problematic for service life considerations). It will be appreciated that the position of the second portion 38, and therefore the position of the protective portion 28, may take into account these distances, with reference to the second portion 38 that does not receive (all EUV imaging radiation) or the first portion 36 that corresponds to the predetermined exposure area 32 of the patterning device MA. That is, the second portion 38 may begin exactly where the exposure area ends, or may begin a distance (eg, 0.25 mm to 2 mm) from the exposure area (ie, toward the edge of the membrane 19) that allows for this heat transfer.

[0103] The protective portion 28 may be disposed on the diaphragm 19 such that the size of the protective portion 28 coincides with the boundary 20. That is, although the protective portion 28 overlaps with the boundary 20, the boundary 20 is disposed on the opposite side 30B of the diaphragm 19. For the sake of clarity, the boundary 20 has a supporting function for the diaphragm 19, while the protective portion 28 has a function of protecting a second portion of the diaphragm 19 (the second portion of the diaphragm 19 is not irradiated by EUV radiation or is only partially irradiated by EUV radiation) from being etched in the plasma environment generated around the diaphragm 18 during EUV exposure. However, the protective portion 28 may also have a different size from the boundary and partially coincide with or even not coincide with the boundary while still covering the second diaphragm area outside the first exposure area. Therefore, the material of the protective portion 28 may be selected so that in addition to providing etching resistance, the protective portion 28 may also be partially transparent to EUV radiation.

[0104] When the size of protective portion 28 does not coincide with border 20, since protective portion 28 covers the entire second portion 38 and border 20 does not cover the entire second portion 38 (on the other side), protective portion 28 extends into the portion of diaphragm 19 that does not coincide with border 20. That is, protective portion 28 also partially extends inwardly onto the area of ​​diaphragm 19 that is not attached to border 20. In some embodiments, the protective portion can be provided during pellicle manufacturing rather than during mask manufacturing. During pellicle manufacturing, the pellicle may not yet be matched to the mask or field. However, during pellicle manufacturing, the pellicle can be produced to have certain standard field sizes, where the protective portion is coated on the periphery accordingly, such as 100%, 80%, etc.

[0105] In some embodiments, the protective portion 28 may be formed of a material suitable for protecting a portion of the diaphragm 19 to which the protective portion 28 is attached from hydrogen etching. For such embodiments, the protective portion 28 may include a capping material (the capping material may be referred to as a coating). The capping material may be considered to cover the second portion 38. The capping material may only cover the second portion 38, i.e., may not cover the first portion 36. The coating may be considered to only partially cover the diaphragm 19. The coating may only cover the non-imaging area of ​​the diaphragm 19 (i.e., the second area of ​​the second portion 38). The coating is only applied outside the imaging field. The coating may not cover the imaging area of ​​the diaphragm 19 (i.e., the first area of ​​the first portion 36). In embodiments, the protective portion 28 may be disposed on the periphery on both (all) sides of the diaphragm 19 (i.e., the first side 30A and the second side 30B (and the edge 30C)). This may provide enhanced protection when compared to the protective portion 28 located only on the first side 30A of the diaphragm 19.

[0106] The cap material may include any of the following materials alone or in combination: carbon nanotubes, graphene, amorphous carbon, (low melting point metal (e.g., temperature below 600°C)), molybdenum (Mo), yttrium (Y), yttrium oxide (Y a O b )、Alumina(Al 2 O 3 )(AlO 2 )、HfO 2 )、ZrO 2 ), ruthenium (Ru), platinum (Pt), gold (Au), zirconium nitride (ZrN), aluminum (Al), zirconium (Zr), silicon (Si), silicon carbide (SiC), silicon oxide (SiO a ), boron (B), boron carbide (B 4 C), boron nitride (BN), titanium (Ti), titanium nitride (TiN). It will be appreciated that these are examples only and other materials may be used. The cap material may include multiple sub-layers formed of different materials.

[0107] It will be appreciated that a greater thickness of such cover material may be provided in the protective portion 28 (i.e., above the second portion 38) relative to the central first portion 36 of the diaphragm 19. That is, in some embodiments, there may be some cover material above the first portion 36. In some embodiments, there may be a relatively thick or thin coating in the exposed area and a relatively thick coating in the periphery. In general, there may be varying degrees of coverage and gradients may be possible. More generally, in embodiments, while the first protective portion may be located at or on the first portion, the extent of the first protective portion at or on the first portion is only less than the extent of the first protective portion at or on the second portion.

[0108] In some embodiments, protective portion 28 may be formed of the same material as the bulk of membrane 19. For such embodiments, protective portion 28 may be a bulk material of increased thickness (e.g., a CNT membrane) that may serve as a sacrificial portion that provides an increased thickness to be etched by hydrogen. In this embodiment, it may be considered that membrane 19 includes protective portion 28, and protective portion 28 includes the same material as first portion 36 and second portion 38 (e.g., carbon nanotubes).

[0109] In some embodiments, the membrane 19 may include a porous membrane. In some embodiments, the membrane 19 includes nanotubes. For example, the membrane 19 may be a fabric formed of CNTs. This may be a carbon nanotube membrane. This is a particularly advantageous material for use as a pellicle membrane in EUV lithography equipment.

[0110] The first portion 36 may be required to provide an EUV transmittance greater than 90%, while the second portion 38 may only need to provide an EUV transmittance greater than 80%. In addition, the first portion 36 may be required to withstand (can withstand) high temperatures (greater than 700° C.), while the second portion 38 may only need to withstand (withstand) lower temperatures (greater than 500° C.). There may be structures in the frame of the patterning device MA for, for example, correction, alignment, etc., and the structures may need to be visible to the measurement sensor, and therefore the second portion 38 may need to be transparent to EUV radiation to some extent, but not to the extent of the first portion 36. In addition, the EUV radiation that may be incident on the second portion 38 may be different from the EUV radiation used for imaging (i.e., EUV imaging radiation). For example, the EUV radiation may not have the same high power as the EUV radiation used for imaging, or may have a different wavelength and reduced dose relative to the EUV imaging radiation, and therefore will not damage (or destroy) the protective portion 28 (cover material).

[0111] Some embodiments of the present disclosure relate to a method for forming a Figure 1 A method of using a pellicle 15 in a lithographic apparatus of a lithographic apparatus LA is shown. Figure 5 Such a method 100 is schematically illustrated in FIG.

[0112] The method 100 includes a step 102 of providing a diaphragm 19 including a first portion 36 and a second portion 38 .

[0113] The method further comprises providing a protective portion 28 at the second portion 38 on one or more sides of the diaphragm 19, which may be provided by a number of different methods as will be explained.

[0114] The protective portion 28 may be provided by an additive or subtractive process, as will be described in more detail.

[0115] In general, the method may include providing a first portion 36 to correspond to a predetermined exposure area 32 for a patterning device MA (ie, for use with the pellicle 15).

[0116] An important aspect is that the pellicle 15 can be modified while in use (e.g. during fabrication of the patterning device MA and / or fabrication of the substrate W) (i.e. by providing the protective portion 28). Once the reticle field size associated with the mask (patterning device MA) is set to a maximum of 104×132 mm 2 This is the case when a 20mm or smaller than full field size is identified. In this case, the pellicle 15 can be selected and processed for the desired design (with a specific field) size. The processing can be considered to provide a protective portion 28 for the pellicle 15 at the second portion 38.

[0117] Mask fabrication may include characterization of the patterning device, e.g., by CD measurement, defect inspection, etc.; and mounting the pellicle on the patterning device, which may include re-qualification of the mask. Substrate (wafer) fabrication may include characterization of the patterning device, e.g., by inspection and / or substrate exposure. If the pellicle 15 is mounted on the patterning device MA, pellicle processing (i.e., selecting and processing the desired design dimensions) may be performed when the substrate W is fabricated.

[0118] In other embodiments, the diaphragm 15 may be provided with the protective portion 28 during the production of the diaphragm 15. This may be the case when the membrane 19 is produced and attached to the frame 17. The membrane 19 may be produced or obtained on the border 20.

[0119] For additive methods, the protective portion 28 may include a cover material (e.g., formed from a material such as those described above) - this may be referred to as a coating. In some embodiments, the method 100 may include a step 104 of masking the first portion 36 using a mask element. This means that the second portion 38 may be covered with a cover material without also covering the first portion 36. The mask element may be a shadow mask. Since the field size is mask-specific, the shadow mask is adapted to the selected mask field size. In an embodiment, the mask element corresponds to a predetermined exposure area 32 of the pattern forming device MA (i.e., the exposure area used with the pellicle 15).

[0120] The method 100 may include a step 106 of depositing a capping material over the second portion 38 (and the masking element) to cover the second portion 38. Since the first portion 36 was masked in step 104, this results in the protective portion 28 being located at the second portion 38.

[0121] The cap material may be deposited using at least one of: thermal evaporation, electron beam evaporation, electron beam deposition, pulsed laser deposition, atomic layer deposition, and remote plasma sputtering.

[0122] For the subtractive method, the protective portion 28 may include a cover material (e.g., formed of a material such as those described above) - this may be referred to as a coating. The method may include coating the cover material over the first portion 36 and the second portion 38, and then removing the cover material from the first portion 36. Thus, the cover material will only remain over the second portion 38 (the cold zone). This results in the protective portion 28 being located at the second portion 38. That is, the diaphragm 19 is fully coated, and then some of the coating (over the first portion 36) is selectively removed to leave only a portion of the coating.

[0123] The method may also include laser annealing, laser ablation, reactive ion etching and / or stripping of the cap material from the first portion 36. This may be done at elevated temperatures, for example, a minimum of 500° C., 600° C. or more realistically 900° C. It will be appreciated that these are examples only and other temperatures may apply.

[0124] The cap material may be a volatile or thermally unstable material suitable for desorption by EUV radiation (e.g., in the range of 200W to several kW, above 200W, above 600W, or above 1kW EUV source power). For example, this may be during imaging (e.g., during exposure of the first field in an EUV lithography apparatus). In an embodiment, this may be during a "pre-scan" as the actual image is printed, as those require very stable conditions. Materials such as amorphous carbon (thick layers) or low melting point metals (e.g., boron) exhibit dewetting behavior above a certain temperature at which the compound desorbs, and may therefore be suitable for use as a cap material when using this method. For example, the temperature at which the compound desorbs may be 500°C, 600°C, 700°C, 800°C, 900°C, or lower or higher, depending on the material.

[0125] For the subtractive method, the protective portion 28 may include the same material (eg, carbon nanotubes) as the first portion 36 and the second portion 38. In this case, the diaphragm 19 may be considered to include the protective portion 28.

[0126] The method may include providing the diaphragm 19 with a certain thickness (in the z-direction), and then partially removing the first portion 36 to reduce the thickness of the first portion 36. The thickness of the protective portion 28 may be considered equal to the thickness that has been removed from the first portion 36. That is, after removal, the first portion 36 may be considered to have a reduced thickness, wherein the thickness of the protective portion 28 is equal to the thickness removed from the first portion 36. The second portion 38 may be considered to include the protective portion 28 (i.e., the total thickness of the second portion 38 (including the protective portion 28) is equal to the thickness of the diaphragm 19 before a portion of the first portion 36 is removed).

[0127] The method may include etching the first portion 36 in a hydrogen plasma, such as an RF plasma etch.

[0128] The protection portion 28 may be considered a sacrificial portion, ie, providing an increased thickness to be hydrogen etched, so that the second portion 38 is not hydrogen etched.

[0129] Providing the protective portion 28 only on the second portion 38 outside the imaging zone has the following advantage: the protective portion 28 protects the membrane 19 from plasma etching while not increasing EUV transmission losses in the imaging zone. The protective portion 28 is not needed in the imaging zone because the high power EUV beam heats the membrane 19 to a sufficiently high temperature to ensure that no or only negligible (CNT) etching occurs in the imaging zone. Outside the imaging zone, where the membrane is relatively cool compared to the imaging zone, the EUV transmission value is insignificant, or at least not as important as in the imaging zone. By preventing plasma, the partial coating on the membrane 19 (the protective portion 28 on the second portion 38) enables a longer service life of the portion of the (CNT) membrane 19 that is not heated during the lithography operation and therefore a longer service life of the (CNT) membrane 19 as a whole.

[0130] Figure 6 Schematically depicts a cross-sectional view of a pellicle 15 and a patterning device MA according to another embodiment. For clarity, the same reference numerals will be used for the same Figure 2 The same and corresponding parts as those described in the drawings are shown in the drawings and, for the sake of brevity, these parts will not be discussed in further detail.

[0131] Figure 6 The surface membrane 15 and Figure 2 The membrane in FIG. 1 is different in that the protective portion includes a plurality of shields: a front shield 40 and a rear shield 42. In addition, the membrane frame 17 includes one or more shield attachment members 44 (e.g., tabs or studs) that are attached or attachable to the front shield 40 at the peripheral edge of the front shield 40. The shield attachment members 44 can be located on the X edge of the membrane 15. The shield attachment members 44 can coincide with the attachment members 24 or be offset from the attachment members 24 (e.g., in FIG. 1 ). Figure 6 ). It will be appreciated that the precise configuration depicted is merely an example, and that other suitable configurations may be used to support the front shield. Thus, more generally, the diaphragm frame 17 supports the front shield 40 on the first side 30A (i.e., the front side) of the diaphragm 19. In other embodiments, the shield may be supported by another different component.

[0132] In addition, the diaphragm frame 17 supports a rear shield 42 located on the opposite second side 30B (i.e., the rear side) of the diaphragm 19. In this embodiment, the rear shield 42 is attached or attachable to the diaphragm frame 17 on the inner edge 17A of the diaphragm frame 17. In other embodiments, the rear shield 42 can be supported by the shield attachment member 44 in a manner similar to the front shield 40. For example, the rear shield 42 can be located between the boundary 20 and the diaphragm frame 17, and the peripheral edge of the rear shield 42 is attached or attachable to the shield attachment member 44.

[0133] The front shield 40 is supported such that there is a front gap between the first side 30A (i.e., the front side) of the diaphragm 19 and the front shield 40. In embodiments, the front gap may be less than 1000 μm. In other embodiments, the front gap may be less than 2000 μm. Generally, the front gap may be a distance such that the plasma flux is sufficiently suppressed. Having a front gap allows the diaphragm 19 to have room to sag, and the size of the front gap may be selected to maximize the sag space of the diaphragm while remaining within the available allowable volume in front of the diaphragm 19. Furthermore, for example, if a different size of the front gap is desired, the thickness of the front shield 40 may be selected to be a thickness that is readily commercially available (such as 200 μm), but may also be selected to be less than (or greater than) 200 μm. It will be appreciated that in some embodiments

[0134] Similarly, the rear shield 42 is supported so that there is a rear gap between the second side 30B (i.e., the rear side) of the diaphragm 19 and the rear shield 42. In an embodiment, the rear gap may be less than 1000 μm. The rear gap may be less than 2000 μm. Typically, the rear gap may be a distance such that the plasma flux is sufficiently suppressed. In an embodiment where the boundary 20 is located between the rear shield 42 and the diaphragm 19, the size of the rear gap may be determined by the thickness of the boundary 20. Otherwise, the rear gap may have a size similar to the front gap. The most critical dimension may be the front gap, because there may be a smaller tolerance or no tolerance here to allow the shield to be positioned. Therefore, a thinner shield (less than 1000 μm) may be preferred. There may be enough space between the diaphragm and the X-direction mask masking blade, the Y nozzle, and / or the EUV inner container to fit the front shield 40.

[0135] It will be appreciated that in some embodiments, there may be substantially no or at least a very small front gap between the first side 30A (i.e., the front side) of the diaphragm 19 and the front shield 40. Similarly, in some embodiments, there may be substantially no or at least a very small rear gap between the second side 30B (i.e., the rear side) of the diaphragm 19 and the rear shield 42. Thus, in some embodiments, the front shield 40 and / or the rear shield 42 may be directly located on, in contact with, and / or supported by the diaphragm 19. In other words, the front gap and / or the rear gap may be optional. For the rear shield 42, this may be the case in embodiments where the boundary 20 is not present and the diaphragm 19 is directly located on the diaphragm frame 17.

[0136] Although there are respective front and rear gaps between the respective front and rear shields 40, 42 and the diaphragm 19, it will be appreciated that the front and rear shields may still be considered to be located on the front and rear sides of the diaphragm. In other words, a protective portion "on at least one side of the diaphragm" does not necessarily need to mean that the protective portion (e.g., shield) is directly on the diaphragm or in contact with the diaphragm or supported by the diaphragm. Thus, this may also cover, for example, a protective portion (e.g., shield) that is located on one side of the diaphragm at a distance (gap) away from the diaphragm, and the protective portion may be supported by another component (such as a membrane frame). Similarly, the protective portion "on the first side and the opposite second side of the diaphragm" may also cover, for example, a protective portion (e.g., a first shield) located on the first side (e.g., the front side) of the diaphragm and a certain distance away from the diaphragm (e.g., a front gap), and may also cover a protective portion (e.g., a second shield) located on the opposite second side (e.g., the rear side) of the diaphragm and a certain distance away from the diaphragm (e.g., a rear gap), wherein the protective portions (e.g., the first shield and the second shield) are supported by another component (such as a diaphragm frame).

[0137] Both the front shield 40 and the rear shield 42 extend inwardly (parallel to the x-axis) relative to the inner edge 17A of the pellicle frame 17 toward the center of the diaphragm 19. In an embodiment, the front shield 40 and the rear shield 42 may extend inwardly at least 1500 μm relative to the inner edge 17A of the pellicle frame 17 (e.g., in the x-direction). In some embodiments, the front shield 40 and the rear shield 42 may additionally or alternatively extend inwardly toward the center of the diaphragm 19 relative to the inner edge 20A of the border 20 (e.g., at least 1500 μm, e.g., in the x-direction). For the former option, this may be the case when the inner edge 17A of the pellicle frame 17 and the inner edge 20A of the border 20 correspond (align) with each other. Figure 6 In the embodiment of the present invention, the front shield 40 and the rear shield 42 extend inwardly to the same extent (i.e., the same distance from each other from the membrane frame 17 (and the same distance from each other from the boundary 20, although the distances from the membrane frame 17 and from the boundary 20 are different because their inner edges 17A, 20A are not aligned with each other)). However, it will be appreciated that in other embodiments, the front shield 40 and the rear shield 42 can extend different distances from the membrane frame 17 and / or the boundary 20. In addition, the front shield 40 and the rear shield 42 can extend different distances in the X direction (for the X boundary) and in the Y direction (for the Y boundary).

[0138] exist Figure 2 In the embodiment of FIG. 1 , the first portion 36 and the second portion 38 of the membrane 19 correspond to the predetermined exposure area 32 and the non-exposure area 34 of the pattern forming device MA, respectively. Figure 6In the embodiment of the present invention, the first portion 36 corresponds to an extended area 46 of the pattern forming device MA, which is larger than the exposure area 32 of the pattern forming device MA. The dotted line 35 still defines the exposure area 32 and the non-exposure area 34 of the pattern forming device MA, wherein the extended area 46 of the pattern forming device MA is shown as being bounded by the dotted line 48. It will be understood that the extended area 46 of the pattern forming device MA includes the exposure area 32 of the pattern forming device MA and the portion between the dotted lines 35 and 48. The exposure area 32 of the pattern forming device MA can be referred to as a quality zone. Other definitions of quality zones can be used, such as an area for measuring optical properties, an area for checking performance, and an area for clamping performance.

[0139] Although the first and second portions 36, 38 of the diaphragm 19 are still defined as shown by the dashed line 39, Figure 6 The dashed line 39 in corresponds to (aligned along the z-axis) dashed line 48 defining the extended area 46 of the pattern forming device MA, rather than corresponding to the dashed line 35 defining the exposed area 32 and the non-exposed area 34 of the pattern forming device MA. Instead, the portion of the diaphragm 19 that can be considered to be the exposed area (because the portion considered to be the exposed area is the only portion that will receive EUV radiation during imaging) and the portion of the diaphragm 19 that can be considered to be the unexposed area (because the portion considered to be the unexposed area does not receive EUV radiation during imaging) are bounded by the dashed line 49. It will be understood that the inwardly extending portion of the front shield 40 (i.e., the inner edge 40A) and the inwardly extending portion of the rear shield 42 (i.e., the inner edge 42A) correspond to the dashed line 39 defining the first portion 36 and the second portion 38 of the diaphragm 19 (aligned along the z-axis), and correspond to (aligned with) the dashed line 48 of the extended area 46 of the pattern forming device MA. It will be understood that in some embodiments, the first portion 36 and the second portion 38 of the diaphragm 19 may correspond to the dashed line 39. Figure 2 The shields are the same as in FIG. 1 (i.e., the front shield and / or the rear shield extend all the way inward to correspond to the exposure area 32 of the patterning device MA). It is important that the shields are not extended so that they would intrude into the EUV radiation beam path over the imaging area because (e.g., unless the shields are as thin as a pellicle) they would then be printed on the wafer, which is undesirable.

[0140] In an embodiment, the extended region 46 of the patterning device MA extends outwardly to a predetermined distance from the exposure region 32 of the patterning device MA. For example, the extended region 46 may extend outwardly to 1000 μm from the exposure region 32. This may enable the shields 40, 42 to not interfere with the EUV radiation (EUV light cone).

[0141] In an embodiment, second portion 38 of diaphragm 19 extends inwardly (parallel to the x-axis) to a predetermined distance relative to inner edge 17A of pellicle frame 17 (and extends inwardly (parallel to the x-axis) to a predetermined distance relative to inner edge 20A of border 20). In embodiments where inner edge 17A of pellicle frame 17 and inner edge 20A of border 20 correspond to (align with) each other, the predetermined distances may be the same. In an embodiment, second portion 38 of diaphragm 19 may extend inwardly at least 1500 μm relative to inner edge 17A of pellicle frame 17. In an embodiment, second portion 38 of diaphragm 19 may extend inwardly at least 1500 μm relative to inner edge 20A of border 20.

[0142] The outward extent of the extended region 46 of the patterning device MA (i.e., shown by dashed line 48) is within the black border of the patterning device MA. Shields 40, 42 extend (inwardly) beyond the border 20 of the pellicle 15 (and frame 17), but remain outside the quality zone (exposure region 32) of the patterning device MA. Because shields 40, 42 extend inwardly relative to the border 20 of the pellicle 15 (and frame 17), shields 40, 42 have the advantage of protecting the pellicle from plasma (i.e., hydrogen plasma etching damage).

[0143] By using (periodic) heater pulses, a pellicle (e.g., a CNT membrane) can be protected from hydrogen plasma etching damage in the lithography apparatus LA. Heat 50 from a pellicle heater (not shown) is applied to the pellicle. Figure 6 4 and is shown as being incident on an area of ​​the diaphragm substantially outside the exposed area of ​​the diaphragm 19 (i.e., outside the dashed line 49). It is important to heat the area outward from the exposed area of ​​the diaphragm 19 because this area will not be heated by the EUV radiation during imaging and will therefore be more susceptible to hydrogen etching (as explained above). It will be appreciated that the area covered by the heat 50 may be the same as the area covered by the EUV radiation. Figure 6 For example, the area covered by heat 50 may extend all the way to border 20 or pellicle frame 17, or even further cover some or all of border 20 and pellicle frame 17. It may be found that irradiating border 20 is not worthwhile due to its high thermal quality.

[0144] However, the pellicle heater only heats the thin membrane 19. The boundary 20 of the pellicle 15 will remain relatively cool because the boundary 20 of the pellicle 15 is a much thicker body with a higher heat capacity and thermal conductivity. Therefore, it has been recognized that there will be a limited size area of ​​the pellicle 19 near the boundary 20 that cannot be fully heated by the heating device (e.g., to the extent required to reduce hydrogen etching to a satisfactory level) because the area is connected to the relatively cool boundary 20. It will be appreciated that this also applies to embodiments where there is no boundary, that is, embodiments where the pellicle 19 is formed directly on the frame 17. That is, due to the thermal mass, the frame 17 of the pellicle 15 will remain relatively cool, and there will be a limited size area of ​​the pellicle 19 near the frame 17 that cannot be fully heated by the heating device (e.g., to the extent required to reduce hydrogen etching to a satisfactory level) because the area is connected to the relatively cool frame 17.

[0145] This region of the diaphragm 19 near the boundary 20 is a problem because the tolerance between the exposed area of ​​the diaphragm 19 and the boundary 20 is only a few mm in the + / -X direction (the + / -Y direction may be slightly more forgiving, for example because the distance between the exposed area of ​​the diaphragm 19 and the boundary 20 may be greater in the Y direction than in the X direction and thus the cold portion of the diaphragm 19 (near the boundary 20) may be further away from the plasma and therefore will be less susceptible to etching because it receives less plasma). This narrow distance means that the film 19 on or near the boundary 20 will receive a non-negligible plasma dose and may result in failure of the diaphragm 19 through etching damage.

[0146] It can be shown that the most heavily etched area on the CNT membrane is not in the field, but outside the exposure zone, i.e., under the reticle shielding blade. The reticle shielding blade does not provide a shielding function (in either the X or Y directions) because the reticle shielding blade is too far from the membrane and there is significant plasma flux leakage under the reticle shielding blade (in both the X and Y directions).

[0147] The shields 40, 42 protect the diaphragm from etching damage by inhibiting the plasma flux to the region of the diaphragm 19 near the boundary 20. That is, the relatively small gaps (front gap and back gap) between the shields 40, 42 and the diaphragm 19 prevent some of the plasma flux from reaching the problem area. The closer the shields 40, 42 are positioned to the diaphragm 19, the more effective the shields will be in preventing the plasma from spreading underneath them. In addition, the shields 40, 42 are transparent to the wavelengths of radiation (e.g., IR radiation and / or DUV radiation) from the diaphragm heater, and thus this allows the diaphragm 19 between the shields 40, 42 to heat. The shields 40, 42 may include aluminum oxide (Al2O3). 2 O 3), sapphire, aluminum oxide (Al 2 O 3 ) coated glass, or sapphire coated glass. Front and rear gaps of less than 1000 μm may be sufficient to suppress the plasma flux to a desired degree. In addition, shields 40, 42 are inert in the plasma. Shields 40, 42 are irradiated by strong plasma, which may cause corrosion of the shields (detrimental to the function of the shields), and corrosion products may be deposited on the mask (reticle) or other parts of the lithography apparatus LA (detrimental to the function of the lithography apparatus LA). Therefore, all parts in the lithography apparatus LA (including shields), especially those close to the light (EUV radiation) beam, should have non-degassing requirements.

[0148] Etch damage to the CNT pellicle after exposure may be shown, and there may be a ring around the exposed area that is most affected (i.e., has the greatest etch damage) (the ring may be referred to as a "fire ring"). This "fire ring" may coincide with the black edge of the mask, making it more difficult to image in the lithography apparatus LA. The "fire ring" is located along the x-axis between the exposed area of ​​the diaphragm 19 and the boundary 20 (and frame 17). Therefore, the shields 40, 42 should be positioned to cover the "fire ring" or the intended location of the "fire ring". For example, the second portion 38 of the diaphragm 19 and therefore the shields 40, 42 may extend inwardly by at least 1500 μm relative to the inner edge 17A of the pellicle frame 17 (and / or the inner edge 20A of the boundary 20) (e.g., in the x-direction) so that the "fire ring" location is covered. As an example, the "ring of fire" may be positioned 1000 μm to 2000 μm away from the exposure area 32 of the pattern forming device MA in the X direction (i.e., away from the defined image field) and / or 1000 μm to 4000 μm away from the exposure area 32 of the pattern forming device MA in the Y direction. Therefore, the second portion 38 of the diaphragm 19 and therefore the shields 40, 42 may extend at least to cover these exemplary positions of the "ring of fire". For example, the first portion 36 of the diaphragm 19 may correspond to an extension area 46 extending 1000 μm outward from the predetermined exposure area 32 for the pattern forming device MA. The extension area 46 may extend outward from the predetermined exposure area 32 of the pattern forming device MA in at least one of a range of 1000 μm to 2000 μm (e.g., in the X direction) and a range of 1000 μm to 4000 μm (e.g., in the Y direction). For example, if the "ring of fire" is positioned 1800 μm from the predetermined exposure area 32 of the pattern forming device MA in the X direction, the first portion 36 of the diaphragm 19 can extend 1700 μm from the predetermined exposure area 32 so that the "ring of fire" will be covered by the front shield 40 and / or the rear shield 42 (because the second portion 38 of the diaphragm 19 will extend a corresponding distance). Examples include the second portion 38 (and therefore the front shield 40 and / or the rear shield 42) extending inwardly relative to the inner edge and / or boundary of the pellicle frame (e.g., relative to the X direction) by at least 1300 μm, at least 1500 μm, at least 2300 μm, or a distance in the range of 1300 μm to 2300 μm.

[0149] Figure 6The shields 40, 42 are shown along the X edge (i.e., the shields 40, 42 extend into the page in the Y direction and shield the X border), but it will be understood that these shields also extend along the Y edge (i.e., these shields shield the Y border). That is, these shields can be considered continuous, so that they can be considered as a single front shield and a single rear shield. For full-field exposure using the entire usable quality area, the shields 40, 42 can prevent the appearance of "fire rings" in both the X edge and the Y edge. In some embodiments, shields may only be present along the X edge and / or the Y edge. The front shield or the rear shield may be discontinuous and may be separated (e.g., in the case where there is only a shield along the X edge). In addition, in some embodiments, shields may be present along both the X edge and the Y edge, but the shields may be separated (i.e., discontinuous) at the corners, for example. In any case, it may be preferred that shields (e.g., front shields and / or rear shields) are present on all four edges of the diaphragm 19 (i.e., two X edges and two Y edges).

[0150] The use of shields 40, 42 may increase the useful life of a pellicle (e.g., a CNT pellicle) in the lithographic apparatus LA, at least due to a reduction in the effects of plasma etching. The use of shields 40, 42 may be preferred over coatings on borders and membrane edges, because coatings may be unstable to thermal stresses and the shields may require careful alignment of deposition with the exposure field. Furthermore, the coating may only serve to protect the border. Additionally, the use of shields 40, 42 may be preferred over thicker CNT layers outside the exposure area of ​​the mask, because this may require challenging process control to align the thicker boundary layer on top of the thin membrane. Furthermore, thicker membranes near the border may still be etched away, which means a shorter useful life than with shields and more carbon etching products in the lithographic apparatus LA.

[0151] It will be understood that although Figure 6 Two shields are shown in FIG, but in some embodiments, there may be a single shield (i.e., a front shield or a rear shield) as this will provide at least some protection and / or may be sufficient to prevent etching to the desired extent. If there is a single shield, it may be preferred that the single shield is the front shield as the front shield will provide more protection than the rear shield.

[0152] Although specific reference may be made herein to the use of lithographic apparatus in IC manufacturing, it should be understood that the lithographic apparatus described herein may have other applications. Other possible applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc.

[0153] Although embodiments of the invention may be specifically referenced herein in the context of lithographic equipment, embodiments of the invention may be used in other equipment. Embodiments of the invention may form part of a mask inspection equipment, a metrology equipment, or any equipment that measures or processes an object such as a wafer (or other substrate) or a mask (or other pattern forming device). These equipment may generally be referred to as lithographic tools. Such lithographic tools may use vacuum conditions or ambient (non-vacuum) conditions.

[0154] Although specific reference has been made above to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that the invention is not limited to optical lithography and may be used in other applications such as imprint lithography where the context permits.

[0155] Where the context permits, embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include a read-only memory (ROM); a random access memory (RAM); a magnetic storage medium; an optical storage medium; a flash memory device; an electrical, optical, acoustic, or other form of propagation signal (e.g., a carrier wave, an infrared signal, a digital signal, etc.), etc. In addition, firmware, software, routines, instructions may be described herein as performing certain actions. However, it will be understood that such descriptions are for convenience only, and such actions are actually generated by a computing device, a processor, a controller, or other device that executes firmware, software, routines, instructions, etc., and in doing so may cause an actuator or other device to interact with the physical world.

[0156] Although specific embodiments of the present invention have been described above, it will be appreciated that the present invention may be practiced in ways other than those described. The above description is intended to be illustrative rather than restrictive. Therefore, it will be apparent to those skilled in the art that the described invention may be modified without departing from the scope of the claims and aspects set forth below.

[0157] 1. A pellicle for use in a lithographic apparatus, the pellicle comprising:

[0158] a diaphragm comprising a first portion and a second portion; and

[0159] A protection portion is located at the second portion on at least one side of the diaphragm.

[0160] 2. The pellicle of clause 1, wherein the second portion, in use, receives no EUV imaging radiation or receives only a small portion of the EUV imaging radiation received by the first portion.

[0161] 3. The pellicle of any one of aspects 1 or 2, wherein the first portion substantially corresponds to a predetermined exposure area of ​​a pattern forming device for use with the pellicle.

[0162] 4. The pellicle of claim 3, wherein the size of the first portion is substantially the same as the predetermined exposure area of ​​the pattern forming device.

[0163] 5. A diaphragm as described in any preceding aspect, wherein the second portion is located at the periphery of the diaphragm.

[0164] 6. The pellicle of aspect 5, wherein the pellicle comprises a border at the perimeter of the diaphragm, wherein the second portion coincides with the border.

[0165] 7. A pellicle as claimed in any preceding aspect, wherein the protective portion comprises a material suitable for protecting the second portion of the membrane from hydrogen etching.

[0166] 8. A pellicle according to any of the preceding aspects, wherein the protective portion is located on at least one of the following:

[0167] a first side and an opposing second side of the diaphragm; and

[0168] the edge of the diaphragm.

[0169] 9. A pellicle as described in any preceding aspect, wherein the protective portion comprises a cover material covering the second portion.

[0170] 10. The surface film according to aspect 9, wherein the cover material comprises at least one of the following: carbon nanotubes, graphene, amorphous carbon, (low melting point metal), molybdenum (Mo), yttrium (Y), yttrium oxide (Y a O b )、Alumina(Al 2 O 3 )(AlO 2 )、HfO 2 )、ZrO 2 ), ruthenium (Ru), platinum (Pt), gold (Au), zirconium nitride (ZrN), aluminum (Al), zirconium (Zr), silicon (Si), silicon carbide (SiC), silicon oxide (SiO a ), boron (B), boron carbide (B 4 C), boron nitride (BN), titanium (Ti) and titanium nitride (TiN).

[0171] 11. The pellicle of any one of aspects 1 to 8, wherein the diaphragm comprises the protective portion, and the protective portion comprises the same material as the first portion and the second portion.

[0172] 12. The pellicle of any one of aspects 1 to 8, wherein the pellicle comprises a pellicle frame and the protective portion comprises a shield, wherein the shield is supported by the pellicle frame.

[0173] 13. The diaphragm of aspect 12, wherein the shield is separated from the diaphragm by a gap, preferably wherein the gap is less than 1000 μm or less than 2000 μm.

[0174] 14. The pellicle of any of aspects 12 or 13, wherein the shield has at least one of the following properties: substantially transparent to heater radiation, substantially transparent to IR radiation, substantially transparent to DUV radiation, and inert in plasma.

[0175] 15. The pellicle according to aspect 14, wherein the shield comprises at least one of the following: aluminum oxide (Al 2 O 3 ), sapphire, aluminum oxide (Al 2 O 3 ) coated glass, and sapphire coated glass.

[0176] 16. The diaphragm of any of aspects 12 to 15, wherein the protective portion comprises a plurality of shields: a first shield on a first side of the diaphragm, and a second shield on an opposing second side of the diaphragm.

[0177] 17. A pellicle as described in any one of Aspects 1 to 2 and Aspects 5 to 16, when not subject to Aspects 3 and 4, wherein the first portion substantially corresponds to an extended area larger than the predetermined exposure area of ​​a pattern forming device used with the pellicle.

[0178] 18. The pellicle of aspect 17, wherein the extended region extends outwardly from the predetermined exposure region of the pattern forming device to a predetermined distance.

[0179] 19. The pellicle of aspect 18, wherein the extended region extends outward from the predetermined exposure region of the pattern forming device by at least one of a distance of 1000 μm, a distance in the range of 1000 μm to 2000 μm, and a distance in the range of 1000 μm to 4000 μm.

[0180] 20. A diaphragm as claimed in any preceding aspect, wherein the second portion extends inwardly to a predetermined distance relative to an inner edge of a diaphragm frame and / or a border at the periphery of the diaphragm.

[0181] 21. A pellicle as described in aspect 20, wherein the second portion extends inwardly relative to the inner edge and / or the border of the pellicle frame by at least one of the following: a distance of at least 1300 μm, a distance of at least 1500 μm, a distance of at least 2300 μm, or a distance in the range of 1300 μm to 2300 μm.

[0182] 22. A pellicle as described in any preceding aspect, wherein the membrane comprises carbon nanotubes.

[0183] 23. A lithographic apparatus operable to form an image of a patterning device on a substrate using a radiation beam, the lithographic apparatus comprising a pellicle arranged in a path of the radiation beam, the pellicle being a pellicle as described in any one of the preceding aspects.

[0184] 24. A method for forming a pellicle for use in a lithographic apparatus, the method comprising:

[0185] providing a diaphragm including a first portion and a second portion,

[0186] A protective portion is provided at the second portion on at least one side of the diaphragm.

[0187] 25. The method of aspect 24, further comprising: providing the protective portion using an additive method or a subtractive method.

[0188] 26. The method according to aspect 25, further comprising:

[0189] providing the protective portion using an additive process, wherein the protective portion comprises a cover material;

[0190] The capping material is deposited on the second portion to cover the second portion.

[0191] 27. The method of clause 26, further comprising using a masking element to mask the first portion.

[0192] 28. The method of clause 27, wherein the mask element substantially corresponds to a predetermined exposure area of ​​a patterning device for use with the pellicle.

[0193] 29. The method of any one of clauses 26 to 28, further comprising depositing the cap material using at least one of: thermal evaporation, electron beam evaporation, electron beam deposition, pulsed laser deposition, atomic layer deposition, and remote plasma sputtering.

[0194] 30. The method according to aspect 25, further comprising:

[0195] providing the protective portion using a subtractive process, wherein the protective portion comprises a cover material;

[0196] applying the cover material to the first portion and the second portion, and

[0197] The cover material is removed from the first portion.

[0198] 31. The method of clause 30, further comprising removing the cap material from the first portion using at least one of: laser annealing, laser ablation, reactive ion etching, and lift-off.

[0199] 32. The method of any of clauses 30 or 31, wherein the cap material is a volatile material or a thermally unstable material adapted to be desorbed by EUV radiation.

[0200] 33. The method as described in aspect 25 also includes using a subtractive method to provide the protective portion, the subtractive method including: providing the diaphragm having a thickness, and partially removing the first portion to reduce the thickness of the first portion, wherein the diaphragm includes the protective portion, and the protective portion includes the same material as the first portion and the second portion.

[0201] 34. The method of clause 33, further comprising etching the first portion in a hydrogen plasma.

[0202] 35. The method of any of aspects 24 to 34, further comprising providing the protective portion on at least one of: a first side and an opposing second side of the diaphragm; and an edge of the diaphragm.

[0203] 36. The method of any of clauses 24 to 35, further comprising providing the first portion to substantially correspond to a predetermined exposure area of ​​a patterning device for use with the pellicle.

[0204] 37. The method of any one of clauses 24 to 36, further comprising providing the protective portion during at least one of fabrication of the pellicle, fabrication of the patterning device, and fabrication of the substrate.

[0205] 38. The method of aspect 24, further comprising providing a pellicle frame, wherein the protective portion comprises a shield and the pellicle frame supports the shield.

[0206] 39. The method of aspect 38, further comprising separating the shield from the diaphragm by a gap.

[0207] 40. The method of any of aspects 38 or 39, further comprising providing a plurality of shields: a first shield located on a first side of the diaphragm, and a second shield located on an opposing second side of the diaphragm.

[0208] 41. The method of any of clauses 38 to 40, further comprising providing the first portion substantially corresponding to an extended area greater than the predetermined exposure area of ​​a patterning device used with the pellicle.

[0209] 42. A pellicle for use in a lithographic apparatus, the pellicle comprising:

[0210] a diaphragm comprising a first portion and a second portion; and

[0211] A protection portion is located at the second portion on at least one side of the diaphragm.

[0212] 43. The pellicle of clause 42, wherein the second portion, in use, receives no EUV imaging radiation or receives only a fraction of the EUV imaging radiation received by the first portion.

[0213] 44. The pellicle of any of aspects 42 or 43, wherein the first portion substantially corresponds to a predetermined exposure area of ​​a patterning device for use with the pellicle.

[0214] 45. The pellicle of aspect 44, wherein the size of the first portion is substantially the same as the size of the predetermined exposure area of ​​the pattern forming device.

[0215] 46. ​​A diaphragm as described in any preceding aspect, wherein the second portion is located at the periphery of the diaphragm.

[0216] 47. The pellicle of aspect 46, wherein the pellicle comprises a border at the perimeter of the diaphragm, wherein the second portion coincides with the border.

[0217] 48. The pellicle of any preceding aspect, wherein the protective portion comprises a material suitable for protecting the second portion of the diaphragm from hydrogen etching.

[0218] 49. The pellicle of any preceding aspect, wherein the protective portion is located on at least one of: a first side and an opposing second side of the diaphragm; and an edge of the diaphragm.

[0219] 50. A pellicle as claimed in any preceding aspect wherein the protective portion comprises a cover material covering the second portion.

[0220] 51. The surface film according to aspect 50, wherein the cover material comprises at least one of the following: carbon nanotubes, graphene, amorphous carbon, (low melting point metal), molybdenum (Mo), yttrium (Y), yttrium oxide (Y a O b )、Alumina(Al 2 O 3 )(AlO 2 )、HfO 2 )、ZrO 2 ), ruthenium (Ru), platinum (Pt), gold (Au), zirconium nitride (ZrN), aluminum (Al), zirconium (Zr), silicon (Si), silicon carbide (SiC), silicon oxide (SiO a ), boron (B), boron carbide (B 4 C), boron nitride (BN), titanium (Ti) and titanium nitride (TiN).

[0221] 52. The pellicle of any of aspects 42 to 49, wherein the membrane comprises the protective portion, and the protective portion comprises the same material as the first portion and the second portion.

[0222] 53. A pellicle as described in any preceding aspect, wherein the membrane comprises carbon nanotubes.

[0223] 54. A lithographic apparatus operable to form an image of a patterning device on a substrate using a radiation beam, the lithographic apparatus comprising a pellicle arranged in a path of the radiation beam, the pellicle being a pellicle as described in any of the preceding aspects.

[0224] 55. A method for forming a pellicle for use in a lithographic apparatus, the method comprising:

[0225] providing a diaphragm including a first portion and a second portion,

[0226] providing a protective portion at the second portion on at least one side of the diaphragm,

[0227] 56. The method of clause 55, further comprising providing the protective portion using an additive process or a subtractive process.

[0228] 57. The method according to aspect 56, further comprising:

[0229] providing the protective portion using an additive process, wherein the protective portion comprises a cover material;

[0230] The capping material is deposited on the second portion to cover the second portion.

[0231] 58. The method of clause 57, further comprising using a masking element to mask the first portion.

[0232] 59. The method of clause 58, wherein the mask element substantially corresponds to a predetermined exposure area of ​​a patterning device for use with the pellicle.

[0233] 60. The method of any one of clauses 57 to 59, further comprising depositing the cap material using at least one of: thermal evaporation, electron beam evaporation, electron beam deposition, pulsed laser deposition, atomic layer deposition, and remote plasma sputtering.

[0234] 61. The method according to aspect 56, further comprising:

[0235] providing the protective portion using a subtractive process, wherein the protective portion comprises a cover material;

[0236] applying the cover material to the first portion and the second portion, and

[0237] The cover material is removed from the first portion.

[0238] 62. The method of clause 61, further comprising removing the cap material from the first portion using at least one of: laser annealing, laser ablation, reactive ion etching, and lift-off.

[0239] 63. The method of any of clauses 61 or 62, wherein the cap material is a volatile material or a thermally unstable material adapted to be desorbed by EUV radiation.

[0240] 64. The method as described in aspect 56 also includes using a subtractive method to provide the protective portion, the subtractive method including: providing the diaphragm having a thickness, and partially removing the first portion to reduce the thickness of the first portion, wherein the diaphragm includes the protective portion, and the protective portion includes the same material as the first portion and the second portion.

[0241] 65. The method of clause 64, further comprising etching the first portion in a hydrogen plasma.

[0242] 66. The method of any one of aspects 55 to 65, further comprising providing the protective portion on at least one of:

[0243] a first side and an opposing second side of the diaphragm; and

[0244] the edge of the diaphragm.

[0245] 67. The method of any of clauses 55 to 66, further comprising providing the first portion to substantially correspond to a predetermined exposure area of ​​a patterning device for use with the pellicle.

[0246] 68. The method of any one of clauses 55 to 67, further comprising providing the protective portion during at least one of fabrication of the pellicle, fabrication of the patterning device, and fabrication of the substrate.

Claims

1. A pellicle for use in a lithographic apparatus, the pellicle comprising: a separator, the separator comprising carbon nanotubes, The diaphragm includes a first portion and a second portion; as well as a protective portion located at the second portion on at least one side of the diaphragm, Wherein, the protective portion comprises a material suitable for protecting the second portion of the diaphragm from etching.

2. The pellicle according to claim 1, wherein: The second portion receives no EUV imaging radiation or receives only a small portion of the EUV imaging radiation received by the first portion in use.

3. The pellicle according to claim 1 or 2, wherein: The first portion substantially corresponds to a predetermined exposure area of ​​a patterning device for use with the pellicle.

4. The pellicle according to claim 3, wherein: The first portion has substantially the same size as the predetermined exposure area of ​​the patterning device.

5. A pellicle as claimed in any preceding claim, wherein: The second portion is located at a periphery of the diaphragm.

6. The pellicle according to claim 5, wherein: The diaphragm includes a border at the periphery of the diaphragm, wherein the second portion coincides in size with the border, and the border is disposed on a side of the diaphragm opposite the protective portion.

7. A pellicle as claimed in any preceding claim, wherein: The protective portion includes a material suitable for protecting the second portion of the diaphragm from hydrogen etching.

8. A pellicle as claimed in any preceding claim, wherein: The protective portion is located on at least one of the following: a first side and an opposing second side of the diaphragm; and the edge of the diaphragm.

9. A pellicle as claimed in any preceding claim, wherein: The protection portion includes a cover material covering the second portion.

10. The pellicle according to claim 9, wherein: The cap material includes at least one of the following: carbon nanotubes, graphene, amorphous carbon, (low melting point metal), molybdenum (Mo), yttrium (Y), yttrium oxide (Y a O b ), aluminum oxide (Al2O3) (AlO2), hafnium oxide (HfO2), zirconium oxide (ZrO2), ruthenium (Ru), platinum (Pt), gold (Au), zirconium nitride (ZrN), aluminum (Al), zirconium (Zr), silicon (Si), silicon carbide (SiC), silicon oxide (SiO a ), boron (B), boron carbide (B4C), boron nitride (BN), titanium (Ti) and titanium nitride (TiN).

11. The pellicle according to any one of claims 1 to 8, wherein: The diaphragm includes the protection portion, and the protection portion includes the same material as the first portion and the second portion.

12. A pellicle as claimed in any preceding claim, wherein: The membrane comprises a layer having the same type of carbon nanotubes in both the first portion and the second portion, and wherein the material of the protective portion covering the second portion of the membrane is transparent to at least a fraction of the EUV imaging radiation received by the first portion.

13. A lithographic apparatus operable to form an image of a patterning device on a substrate using a radiation beam, the apparatus comprising a pellicle arranged in a path of the radiation beam, the pellicle being a pellicle according to any preceding claim.

14. A method for forming a pellicle for use in a lithographic apparatus, the method comprising: providing a membrane including carbon nanotubes, the membrane including a first portion and a second portion, providing a protective portion at the second portion on at least one side of the diaphragm, Wherein, the protective portion comprises a material suitable for protecting the second portion of the diaphragm from etching.

15. The method of claim 14, further comprising: The protective portion is provided using either an additive or a subtractive approach.

16. The method of claim 15, further comprising: providing the protective portion using an additive process, wherein the protective portion comprises a cover material; The capping material is deposited on the second portion to cover the second portion.

17. The method of claim 16, further comprising: A masking element is used to mask the first portion.

18. The method of claim 17, the mask element substantially corresponding to a predetermined exposure area of ​​a patterning device for use with the pellicle.

19. The method of any one of claims 16 to 18, further comprising depositing the cap material using at least one of: thermal evaporation, electron beam evaporation, electron beam deposition, pulsed laser deposition, atomic layer deposition, and remote plasma sputtering.

20. The method of claim 15, further comprising: providing the protective portion using a subtractive process, wherein the protective portion comprises a cover material; applying the cover material to the first portion and the second portion, and The cover material is removed from the first portion.

21. The method of claim 20, further comprising removing the cap material from the first portion using at least one of: laser annealing, laser ablation, reactive ion etching, and lift-off.

22. The method of claim 20 or 21, wherein: The cap material is a volatile material or a thermally unstable material that is desorbed by EUV radiation.

23. The method of claim 15, further comprising providing the protective portion using a subtractive method, the subtractive method comprising: The diaphragm having a thickness is provided, and the first portion is partially removed to reduce the thickness of the first portion, wherein the diaphragm includes the protective portion, and the protective portion includes the same material as the first portion and the second portion.

24. The method of claim 23, further comprising etching the first portion in a hydrogen plasma.

25. The method of any one of claims 14 to 24, further comprising providing the protective portion on at least one of: a first side and an opposing second side of the diaphragm; and the edge of the diaphragm.

26. The method of any one of claims 14 to 25, further comprising: The first portion is provided to substantially correspond to a predetermined exposure area of ​​a patterning device for use with the pellicle.

27. The method of any one of claims 14 to 26, further comprising: The protective portion is provided during at least one of fabrication of the pellicle, fabrication of the patterning device, and fabrication of the substrate.

Images