Diaphragm for EUV lithography

Abstract

A septum configured to transmit extreme ultraviolet radiation, the septum including a nanostructure configured to absorb deep ultraviolet radiation, and a method for forming the septum. The diaphragm may form part of an EUV lithographic apparatus, for example as part of a spectral purity filter, pellicle assembly, or dynamic airlock assembly.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to EP application 23159614.9, filed on March 2, 2023, and which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a diaphragm, a patterning device assembly, and a dynamic airlock assembly for EUV lithography. Background Art

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

[0005] To project a pattern onto a substrate, a lithographic apparatus uses electromagnetic radiation. The wavelength of this radiation determines the minimum size of features that can be formed on the substrate. Compared to lithographic apparatuses that can use radiation with longer wavelengths, such as 193 nm, lithographic apparatuses that use extreme ultraviolet (EUV) radiation with wavelengths in the 4 nm to 20 nm range (e.g., 6.7 nm or 13.5 nm) can be used to form smaller features on a substrate.

[0006] Radiation used by a lithographic apparatus may include radiation of undesirable wavelengths, such as, for example, deep ultraviolet (DUV) radiation and / or infrared radiation. Radiation of undesirable wavelengths may cause lithographic errors.

[0007] It is desirable to reduce the presence of radiation of undesirable wavelengths while maintaining or increasing the transmission of EUV radiation. Summary of the Invention

[0008] According to a first aspect of the present disclosure, there is provided a membrane configured to transmit extreme ultraviolet radiation, the membrane comprising nanostructures configured to absorb deep ultraviolet radiation.

[0009] Extreme ultraviolet (EUV) radiation may include radiation having a wavelength of about 4 nm or greater. Extreme ultraviolet radiation may include radiation having a wavelength of about 20 nm or less.

[0010] The membranes of the present disclosure have been found to have increased EUV radiation transmittance compared to known membranes. The membranes can be configured to have an EUV transmittance of about 90% or greater. The membranes can be configured to have an EUV transmittance of about 95% or greater.

[0011] Deep ultraviolet radiation may include radiation having a wavelength of about 100 nm or greater. Deep ultraviolet radiation may include radiation having a wavelength of about 400 nm or less.

[0012] The diaphragm may be configured to have a DUV absorptivity of about 80% or less. The diaphragm may be configured to have a DUV absorptivity of about 30% or greater. The diaphragm may be configured to have a DUV absorptivity of about 40% or greater. The diaphragm may be configured to have a DUV absorptivity of about 50% or greater. The diaphragm may be configured to have a DUV absorptivity of about 60% or greater. The diaphragm may be configured to have a DUV absorptivity of about 70% or greater.

[0013] The nanostructure may include constituent elements (e.g., nanoparticles) having a size of about 1 nm or greater. The nanostructure may include constituent elements having a size of about 100 nm or less. The nanostructure may include constituent elements having a size of about 50 nm or less. The nanostructure may include constituent elements having a size of about 25 nm or less. The nanostructure may include constituent elements having a size of about 10 nm or less. The nanostructure may include constituent elements having a size of about 7 nm or less. The nanostructure may include constituent elements having a size of about 5 nm or less.

[0014] The nanostructures can utilize one or more nanoscale absorption mechanisms, such as, for example, quantum confinement of radiation, plasmon excitation and / or formation of plasmon polaritons, metal-ligand charge transfer effects, and the like, thereby advantageously achieving equivalent or increased absorption of DUV radiation and / or infrared radiation at a thinner membrane thickness than known membranes. In this manner, the nanostructures can advantageously filter out equivalent or increased amounts of DUV radiation and / or infrared radiation while being thin enough to maintain or increase EUV transmission compared to known membranes. For example, the membranes of the present disclosure can be approximately half or less than half the thickness of known membranes, thereby improving EUV radiation transmission while providing equivalent or increased absorption of DUV radiation and / or infrared radiation.

[0015] The known separators are complex multi-layer structures synthesized in a multi-step manufacturing process. Compared to the known separators, the separators of the present disclosure provide equivalent or improved performance using a simpler structure and manufacturing process.

[0016] The nanostructures may include semiconductor nanoparticles.

[0017] Compared to known membranes, it has been found that semiconductor nanoparticles provide advantageous properties to the membrane, such as increased EUV radiation transmission, increased DUV radiation and / or infrared radiation absorption, increased emissivity to improve temperature regulation, sufficient mechanical strength at reduced membrane thickness, sufficient tension to reduce the risk of membrane sagging or breaking, etc.

[0018] The semiconductor nanoparticles may include silicon crystals.

[0019] Compared to known diaphragms, it has been found that silicon crystalline nanoparticles provide advantageous properties to the diaphragm, such as increased EUV radiation transmission, increased DUV radiation and / or infrared radiation absorption, increased emissivity to improve temperature regulation, sufficient mechanical strength at reduced diaphragm thickness, sufficient tension to reduce the risk of diaphragm sagging or breaking, etc.

[0020] The size of the silicon crystal may be about 7 nm or less. The size of the silicon crystal may be about 5 nm or less.

[0021] The term "size" of a silicon crystal may refer to the average crystal diameter when the crystal is spherical, and may refer to the length of the major axis when the crystal is non-spherical.

[0022] Compared to known diaphragms, it has been found that silicon crystals of about 7 nm or less provide the diaphragm with advantageous properties, such as increased EUV radiation transmission, increased DUV radiation and / or infrared radiation absorption, increased emissivity for improved temperature regulation, sufficient mechanical strength at reduced diaphragm thickness, sufficient tension to reduce the risk of diaphragm sagging or breaking, etc.

[0023] Semiconductor nanoparticles may include quantum dots.

[0024] The average quantum dot size can be smaller than the radius of a Bohr exciton (ie, a quasiparticle corresponding to a bound state of an electron-hole pair).

[0025] When the quantum dot is spherical, the term "size" of the quantum dot may refer to the average particle diameter, and when the quantum dot is non-spherical, the term "size" of the quantum dot may refer to the length of the major axis.

[0026] Quantum dots advantageously provide enhanced and tunable optical properties due to quantum confinement of electromagnetic radiation. The nanostructure of the membrane, including the quantum dots, is designed so that the size of the semiconductor nanoparticles is smaller than the Bohr exciton radius, thereby generating quantum confinement of their electronic wave functions, causing the electronic structure to become size-dependent and thereby affecting their electronic and optical properties. In other words, the size of the quantum dots can be set so that they reside in the strong quantum confinement regime, rather than the intermediate or weak quantum confinement regimes.

[0027] The quantum dots are configured to absorb DUV radiation. By selecting the size and / or shape of the quantum dots, the discrete electron energy levels present in the quantum dots can be tailored to absorb DUV radiation.

[0028] The quantum dots may have a size of about 5 nm or larger. The quantum dots may have a size of about 7 nm or smaller. These sizes have been found to be particularly effective in absorbing DUV radiation.

[0029] Quantum dots can include crystals with a rounded morphology (eg, spherical or at least partially spherical).

[0030] Quantum dots can form well-defined lattices.

[0031] Depending on the material used to form the quantum dots in the membrane, the quantum dots can be made from a wide variety of materials, each having its own or unique applications.

[0032] The quantum dots may include silicon quantum dots.

[0033] Silicon quantum dots have been found to be particularly effective at absorbing DUV radiation while maintaining or improving the EUV radiation transmittance of the membrane compared to known membranes.

[0034] Silicon quantum dots can have a size of about 5 nm or larger. Silicon quantum dots can have a size of about 7 nm or smaller. These sizes have been found to be particularly effective in absorbing DUV radiation and / or providing increased emissivity.

[0035] Silicon can be doped. Doping silicon can increase its emissivity. For example, possible dopants include phosphorus, boron, arsenic, gallium, aluminum, indium, antimony, bismuth, and germanium.

[0036] The nanostructures may include metallized nanoparticles.

[0037] For metallic nanoparticles, the collective interaction of their electrons with external electromagnetic fields (i.e., incident radiation) can induce localized surface plasmon polaritons, which are collective charge oscillations. The consequences of plasmon excitation include selective photon absorption, scattering, and light intensity enhancement (e.g., enhanced absorption of DUV radiation) at a certain resonant wavelength.

[0038] The metallized nanoparticles have been found to provide the membrane with advantageous properties compared to known membranes, such as increased EUV radiation transmission, increased DUV radiation and / or infrared radiation absorption, increased emissivity for improved temperature regulation, sufficient mechanical strength at reduced membrane thickness, sufficient tension to reduce the risk of membrane sagging or breaking, etc.

[0039] The metallized nanoparticles may include MoSi2 crystals.

[0040] Compared to known diaphragms, it has been found that MoSi2 crystals provide advantageous properties to the diaphragm, such as increased EUV radiation transmission, increased DUV radiation and / or infrared radiation absorption, increased emissivity for improved temperature regulation, sufficient mechanical strength at reduced diaphragm thickness, sufficient tension to reduce the risk of diaphragm sagging or breaking, etc.

[0041] The metallized nanoparticles may include Mo5Si3 crystals and / or Mo3Si crystals.

[0042] It has been found that Mo5Si3 crystals and / or Mo3Si crystals increase the emissivity of the diaphragm.

[0043] The metallic nanoparticles may include Ga crystals.

[0044] The nanostructures may include a matrix or base of semiconductor nanoparticles and metallic nanoparticles.

[0045] The matrix of semiconductor nanoparticles and metallized nanoparticles has been found to provide the membrane with advantageous properties compared to known membranes, such as increased EUV radiation transmission, increased DUV radiation and / or infrared radiation absorption, increased emissivity for improved temperature regulation, sufficient mechanical strength at reduced membrane thickness, sufficient tension to reduce the risk of membrane sagging or breaking, etc.

[0046] The semiconductor nanoparticles may include Si crystals. The metallized nanoparticles may include MoSi2 crystals. The metallized nanoparticles may include Mo5Si3 crystals. The metallized nanoparticles may include Mo3Si crystals.

[0047] Compared to known diaphragms, it has been found that the matrix of silicon crystals and molybdenum silicide crystals provides the diaphragm with advantageous properties, such as increased EUV radiation transmission, increased DUV radiation and / or infrared radiation absorption, increased emissivity for improved temperature regulation, sufficient mechanical strength at reduced diaphragm thickness, sufficient tension to reduce the risk of diaphragm sagging or breaking, etc.

[0048] The diaphragm may include N.

[0049] It has been found that the introduction of N advantageously improves the tensile properties of the diaphragm, such that the diaphragm has a lower risk of breaking or sagging compared to known diaphragms.

[0050] The separator may include less than about 5 atomic % or less than about 5 atomic % N.

[0051] The membrane can include trace amounts of nitrogen (i.e., less than about 5 atomic %). The trace amounts of nitrogen can be trapped within a nitrogen-containing oxide shell. The native oxide shell can naturally grow within the nanostructure. The matrix can be referred to as MoSiSi:N. MoSiSi:N membranes have been found to have a transmittance of greater than about 95% for EUV radiation. The presence of trace amounts of nitrogen in the core of the MoSiSi:N membrane can provide enhanced EUV absorption.

[0052] The separator may include between about 5 atomic % N and about 20 atomic % N.

[0053] The membrane may include non-trace amounts of nitrogen (i.e., greater than or equal to about 5 atomic % and less than or equal to about 20 atomic %). The matrix may be referred to as MoSiN. MoSiN may advantageously improve the emissivity of the membrane. This, in turn, may reduce or eliminate the need for an emissive layer (e.g., Ru and / or Mo), thereby improving the membrane's EUV radiation transmittance compared to known membranes.

[0054] The membrane may have a thickness of about 8 nm or less.

[0055] The diaphragms of the present disclosure are much thinner than known diaphragms, thereby advantageously improving EUV radiation transmission compared to known diaphragms, while maintaining or improving other desirable properties compared to known diaphragms, such as increased DUV radiation and / or infrared radiation absorption, increased emissivity to improve temperature regulation, sufficient mechanical strength at reduced diaphragm thickness, sufficient tension to reduce the risk of diaphragm sagging or breaking, etc.

[0056] The separator may include a core layer and a cover layer. The nanostructure may be present in the core layer.

[0057] The introduction of a cover layer advantageously improves the mechanical and / or optical properties of the diaphragm, and / or protects the core layer of the diaphragm, and / or enables the diaphragm to perform a greater number of functions.

[0058] The core layer may have a thickness of about 5 nm or less.

[0059] When the core layer thickness reaches very small thicknesses (e.g., 5 nm or less), spectral analysis shows an increase in DUV radiation absorption achieved by the membrane compared to known membranes. This can be attributed to nanoscale absorption mechanisms such as quantum confinement of radiation, plasmon excitation and / or plasmon polariton formation, metal-ligand charge transfer effects, etc., depending on the constituent elements of the nanostructure.

[0060] The thickness of the core layer may correspond to the size of a single nanoparticle of the constituent elements forming the nanostructure. That is, the core layer may have a thickness corresponding to a single grain of the nanostructure.

[0061] The capping layer may include SiO2 and / or ZrO2.

[0062] The capping layer comprising SiO2 and / or ZrO2 advantageously provides protection against contaminants. For example, hydrocarbons and / or metals (eg, tin) may be outgassed from, for example, the resist on the substrate W. The capping layer protects the core layer from these contaminants.

[0063] The capping layer may include Ru and / or Mo.

[0064] A capping layer comprising Ru and / or Mo advantageously improves the emissivity of the diaphragm. This allows the diaphragm to absorb more infrared radiation, thereby improving the spectral filtering function of the diaphragm. Generally, improving the emissivity of the diaphragm also improves the temperature regulation of the diaphragm by allowing absorbed heat to dissipate from the diaphragm.

[0065] The addition of one or more capping layers comprising materials such as SiO2 and / or ZrO2 and / or Ru and / or Mo may reduce the EUV radiation transmittance of the membrane. However, due to the nanostructure of the core layer, the membrane still achieves equivalent or improved EUV radiation transmittance compared to known membranes.

[0066] The diaphragm may include an unsupported portion.

[0067] While known membranes rely on a body material or substrate for supporting the membrane, the membranes of the present disclosure do not require a body or substrate, thereby advantageously reducing undesirable interactions (eg, EUV radiation absorption) compared to known membranes.

[0068] According to a second aspect of the present disclosure, there is provided a spectral purity filter for EUV lithography, the spectral purity filter comprising the membrane of the first aspect.

[0069] According to a third aspect of the present disclosure, there is provided a patterning device assembly for EUV lithography, the patterning device assembly comprising the membrane of the first aspect.

[0070] The patterning device assembly may include: a membrane (ie, a pellicle) according to the first aspect of the present disclosure, a frame for supporting the pellicle, and a patterning device attached to the frame.

[0071] According to a fourth aspect of the present disclosure, a dynamic airlock assembly for EUV lithography is provided, wherein the dynamic airlock assembly comprises the diaphragm of the first aspect.

[0072] According to a fifth aspect of the present disclosure, there is provided a lithography system comprising the diaphragm of the first aspect.

[0073] The lithography system may include a first chamber having a projection system. The projection system may be configured to project a patterned radiation beam onto a substrate. The lithography system may include a second chamber including a substrate table. The substrate table may be configured to hold a substrate. The lithography system may include a channel extending between the first chamber and the second chamber. The channel may be configured to receive a purge fluid flow. The perimeter of the channel may be defined by a wall. The wall of the channel may include a purge fluid inlet. The channel and the purge fluid flow may be referred to as a dynamic airlock assembly.

[0074] According to a sixth aspect of the present disclosure, there is provided a method of forming a membrane configured to transmit extreme ultraviolet radiation, the method comprising forming a nanostructure configured to absorb deep ultraviolet radiation.

[0075] Forming the nanostructures may include physical vapor deposition. Physical vapor deposition may include sputtering deposition.

[0076] Forming the nanostructure may include chemical vapor deposition, which may include atomic layer deposition.

[0077] Using a deposition process advantageously avoids the use of more complex and less efficient chemical methods involving solvents.The deposition process can be CMOS compatible.

[0078] Forming the nanostructure may include sputter deposition using a sputter target.

[0079] The sputtering target may be a MoSiSi sputtering target. The sputtering target may be a molybdenum silicide sputtering target. The sputtering target may include about 15 atomic % or more of Mo. The sputtering target may include about 25 atomic % or less of Mo.

[0080] The method may include using a first sputtering target comprising Si. The method may include using a second sputtering target comprising MoSi2.

[0081] The method may include using a first sputtering target comprising a matrix material and a second sputtering target comprising an inclusion material. The matrix material may include silicon. The matrix material may include silicon nitride. The inclusion material may include molybdenum silicide. The inclusion material may include zirconium silicide. The inclusion material may include ruthenium silicide. The inclusion material may include tungsten silicide.

[0082] The method may include adjusting power provided to the sputtering target to adjust the composition of the membrane.

[0083] The method may include providing a power of about 50 W or more to the sputtering target. The method may include providing a power of about 1000 W or less to the sputtering target. The method may include providing a power of about 300 W or less to the sputtering target.

[0084] The method may comprise performing the deposition in the presence of N2. The method may comprise performing the deposition in the presence of a flow of N2.

[0085] Nitriding the metal silicide or silicon can be accomplished by sputtering the metal silicide or silicon substrate with a plasma. The sputtering can be reactive sputtering. The plasma can be any suitable plasma. The plasma can include nitrogen. The plasma can include a mixture of argon and nitrogen. Argon can be included to provide an inert atmosphere. The ratio of argon to nitrogen can vary. Having a greater proportion of nitrogen in the gas mixture will result in a greater amount of nitrogen being incorporated into the diaphragm.

[0086] The sputtering target may include Mo and Si. The sputtering target may include a Mo content of about 20 atomic %.

[0087] This Mo content advantageously enables trace amounts of N in the nanostructure, which has been found to improve DUV absorption.

[0088] The sputtering target may include Mo and Si. The sputtering target may include a Mo content of about 22.5 atomic %.

[0089] This Mo content advantageously enables non-trace amounts of N in the nanostructure, which has been found to improve emissivity and infrared absorption even at very small thicknesses (e.g., about 5 nm or less). This advantageously reduces or eliminates the need for emissive capping layers (e.g., Ru-Mo), which in turn improves EUV radiation transmittance and reduces the complexity of the membrane structure.

[0090] It should be understood that features described with respect to any aspect can be combined with features described with respect to any other aspect of the disclosure. Unless features of various aspects of the disclosure are mutually exclusive, all combinations of various aspects of the disclosure can be combined with each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which corresponding reference numerals indicate corresponding parts, and in which:

[0092] Figure 1 A lithographic system comprising a lithographic apparatus, a radiation source and three membranes according to aspects of the present disclosure is schematically depicted.

[0093] Figure 2 A side view of a membrane according to the present disclosure is schematically depicted.

[0094] Figure 3 Two scanning transmission electron microscope images of membranes formed according to the present disclosure are shown.

[0095] Figure 4 The DUV absorption of different membranes having nanostructures including MoSi2 crystals and Si crystals according to the present disclosure is shown.

[0096] Figure 5 A side view of a first multilayer separator according to the present disclosure is schematically depicted.

[0097] Figure 6 A side view of a second multilayer separator according to the present disclosure is schematically depicted. DETAILED DESCRIPTION

[0098] Figure 1 A lithographic system is shown comprising a radiation source SO and a lithographic apparatus LA. The radiation source SO is configured to generate an extreme ultraviolet (EUV) radiation beam B and to supply the EUV radiation beam B to the lithographic apparatus LA. The lithographic apparatus LA comprises an illumination system IL, a support structure MT configured to support a patterning device MA (e.g., a mask), a projection system PS, and a substrate table WT configured to support a substrate W.

[0099] The illumination system IL is configured to condition the EUV radiation beam B before it is incident on the patterning device MA. Therefore, the illumination system IL may include a faceted field mirror arrangement 10 and a faceted pupil mirror arrangement 11. The faceted field mirror arrangement 10 and the faceted pupil mirror arrangement 11 together provide an EUV radiation beam B having a desired cross-sectional shape and a desired intensity distribution. In addition to or instead of the faceted field mirror arrangement 10 and the faceted pupil mirror arrangement 11, the illumination system IL may include other mirrors or arrangements.

[0100] After being so conditioned, the EUV radiation beam B interacts with the patterning device MA. As a result of this interaction, a patterned EUV radiation beam B' is produced. The projection system PS is configured to project this patterned EUV radiation beam B' onto the substrate W. For this purpose, the projection system PS may comprise a plurality of mirrors 13, 14 configured to project the patterned EUV radiation beam B' onto the substrate W held by the substrate table WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B' so as to form an image having features that are smaller than corresponding features on the patterning device MA. For example, a reduction factor of 4 or 8 may be applied. Although the projection system PS is Figure 1 In FIG. 2 , the projection system PS is shown with only two mirrors 13 , 14 , but the projection system PS may comprise a different number of mirrors (eg 6 or 8 mirrors).

[0101] The substrate W may include a previously formed pattern. In this case, the lithographic apparatus LA aligns the image formed by the patterned EUV radiation beam B′ with the previously formed pattern on the substrate W.

[0102] 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, illumination system IL, and / or projection system PS.

[0103] For example, Figure 1 The radiation source SO shown in FIG. 1 is of a type that may be referred to as a laser produced plasma (LPP) source. Laser system 1, for example, may comprise a CO2 laser and is arranged to deposit energy via a laser beam 2 into a fuel, such as tin (Sn), provided, for example, by a fuel emitter 3. Although described below with reference to tin, any suitable fuel may be used. The fuel may, for example, be in liquid form and may be a metal or alloy. Fuel emitter 3 may comprise a nozzle configured to direct the tin, for example, in the form of droplets, along a trajectory toward a plasma formation region 4. Laser beam 2 is incident on the tin at plasma formation region 4. The laser energy is deposited into the tin, causing a tin plasma 7 to be generated at plasma formation region 4. Radiation, including EUV radiation, is emitted from plasma 7 during deexcitation and recombination of electrons with ions of the plasma.

[0104] EUV radiation from the plasma is collected and focused by a collector 5. For example, the collector 5 comprises a near-normal-incidence radiation collector 5 (sometimes more generally referred to as a normal-incidence radiation collector). The collector 5 can 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 can have an elliptical configuration with two focal points. As discussed below, the first of the two focal points can be at the plasma formation region 4, and the second of the two focal points can be at the intermediate focus 6.

[0105] 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 directing mirrors and / or a beam expander and / or other optical devices. The laser system 1, the radiation source SO, and the beam delivery system may together be considered a radiation system.

[0106] 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 in 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 adjacent to an opening 8 in an enclosure 9 of the radiation source SO.

[0107] 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.

[0108] EUV sources, such as those that use plasma to generate EUV radiation, actually emit not only desirable "in-band" EUV radiation but also unwanted (out-of-band) radiation. This out-of-band radiation is most pronounced in the deep UV (DUV) radiation range (from 100 nm to 400 nm). Furthermore, in the case of some EUV sources (e.g., laser-generated plasma EUV sources), the radiation from the laser (typically around 10.6 microns) can also be a significant source of unwanted (out-of-band) infrared (IR) radiation.

[0109] In lithographic apparatus LA, spectral purity is desirable for several reasons. One reason is that the resist of substrate W is sensitive to radiation of out-of-band wavelengths, and therefore the image quality of an exposed pattern applied to the resist may degrade if the resist is exposed to such out-of-band radiation. Furthermore, out-of-band infrared radiation (e.g., 10.6 micrometer radiation in some laser-generated plasma sources) can cause undesirable and unnecessary heating of patterning device MA, substrate W, and optics 10, 11, 13, 14 within lithographic apparatus LA. Such heating can result in damage to these components, shortening of their operational lifespan, and / or defects or distortions in the pattern projected and applied to resist-coated substrate W.

[0110] In a lithographic apparatus LA (and / or method), it is desirable to reduce the intensity loss of EUV radiation used to apply a pattern to a resist-coated substrate W. One reason for this is that, ideally, as much EUV radiation as possible should be made available for applying the pattern to the substrate W, e.g., to reduce exposure time and increase throughput. At the same time, it is desirable to reduce the amount of undesired radiation (e.g., out-of-band radiation) that passes through the lithographic apparatus LA and impinges on the substrate W.

[0111] The diaphragm 100, 200, 300 may be provided to reduce the presence of out-of-band radiation (e.g., DUV and / or infrared radiation) while maintaining a high level of EUV radiation transmission in the lithographic apparatus LA. The diaphragm 100, 200, 300 may be referred to in the art as an EUV diaphragm. Typically, the diaphragm 100, 200, 300 comprises a thin film having an independent or free-standing portion that is configured to transmit as much EUV radiation as possible to ensure maximum throughput. The diaphragm 100, 200, 300 may also provide additional functionality depending on its location in the lithographic apparatus LA. Figure 1 In the example of FIG. 1 , the diaphragms 100 , 200 , 300 are provided at three locations.

[0112] A first diaphragm 100 is located in the radiation source SO and forms part of a spectral purity filter. The spectral purity filter may be located elsewhere in the lithography system. Spectral purity filter 100 may substantially transmit EUV radiation, but substantially block radiation of other wavelengths, such as deep ultraviolet (DUV) radiation and / or infrared radiation. The spectral purity filter may include a frame, and diaphragm 100 may extend across the frame in an unsupported manner.

[0113] The second diaphragm 200 is located near the patterning device MA and forms part of the patterning device assembly. This second diaphragm 200 can be referred to as a pellicle. Radiation interacts with the patterning device MA to form an image on the substrate W. Contamination (e.g., particles or particulate contamination) on the surface of the patterning device MA can negatively impact imaging in the lithographic apparatus LA and lead to manufacturing defects on the substrate W. The diaphragm 200 can be configured to protect the patterning device MA from airborne particles and other forms of contamination. The diaphragm 200 used to protect the patterning device MA can be referred to as a pellicle or can form part of a pellicle assembly. The pellicle assembly can include a frame, and the diaphragm 200 can extend unsupported across the frame. The pellicle 200 has a set of performance specifications achieved by the properties of its constituent materials and structure. Relevant performance specifications include: the pellicle 200 does not distort imaging, sufficiently transmits EUV radiation, and does not contaminate critical components in the lithographic apparatus LA. The primary function of the pellicle 200 is to protect the patterning device MA from particle contamination.

[0114] The third diaphragm 300 is located between the projection system PS and the substrate W and forms part of a dynamic airlock assembly. The third diaphragm 300 may be referred to as a dynamic airlock diaphragm. The projection system PS of the lithographic apparatus LA is held in a first chamber 15, and the substrate table WT is held in a second chamber 16. The first and second chambers 15, 16 are maintained under vacuum conditions. Contaminants may be generated in the second chamber 16 and diffuse toward the first chamber 15. For example, hydrocarbons and / or metals (such as tin) may outgas from the resist on the substrate W and travel toward the highly sensitive optical components within the projection system PS. Exposure of the substrate to EUV radiation may increase the amount of contaminants generated in the second chamber 16. Contaminants may accumulate on optical components within the projection system PS, negatively impacting their performance. For example, contaminants may accumulate on the reflective surfaces of mirrors within the projection system PS and reduce their reflectivity. Reducing the reflectivity of the mirrors in the projection system PS may reduce the amount of EUV radiation reaching the substrate W, which in turn may reduce substrate throughput because a longer amount of time may be required for the same EUV dose to be applied to the substrate W. The lithography system may include a dynamic airlock assembly configured to protect optical components in the first chamber 15 from contaminants generated in the second chamber 16.

[0115] The dynamic airlock assembly may include a channel 17 extending between a first chamber 15 and a second chamber 16. Channel 17 has a perimeter defined by a wall 19. Channel 17 may be supplied with a purge fluid flow via a purge fluid inlet (not shown) disposed in the wall 19 of channel 17. The purge fluid may, for example, include hydrogen. Other fluids, such as helium, nitrogen, argon, and / or any mixture thereof, may also be used. The purge fluid may be selected to have a low diffusion coefficient (e.g., lower than the diffusion coefficient of hydrogen) for contaminants present in the lithographic apparatus. The purge fluid flow through channel 17 toward the second chamber 16 forms a purge fluid curtain. The purge fluid curtain is configured to reduce the amount of contaminants that reach the second chamber 16 from the first chamber 15, thereby protecting the projection system PS from contamination. Both channel 17 and the purge fluid curtain are configured to allow EUV radiation to pass from the first chamber 15 to the second chamber 16, enabling photolithographic exposure to occur. The membrane 300 may prevent contaminants from reaching the first chamber 15 via channel 17 or significantly reduce the amount of contaminants that reach the first chamber 15 from the second chamber 16.

[0116] Before the patterned radiation beam B' leaves the projection system PS and reaches the substrate W to form a pattern in the EUV-sensitive resist, EUV radiation present in the patterned radiation beam B' can be filtered from out-of-band radiation present in the patterned radiation beam B'. The out-of-band radiation can include DUV radiation (e.g., having a wavelength in the range of about 100 nm to about 400 nm, inclusive). The DUV radiation may not contribute to the imaging of the patterning device MA on the substrate W, but may provide an undesirable global background contribution that may result in a loss of contrast at the substrate W. For this reason, a dynamic air lock diaphragm 300 can be provided to reduce the presence of DUV radiation and / or infrared radiation before the patterned radiation beam B' is incident on the substrate W.

[0117] The dynamic airlock assembly can be located elsewhere in the lithography system, and / or other dynamic airlock assemblies can be provided. For example, the dynamic airlock assembly can be configured to protect the illumination system IL. The dynamic airlock assembly can be located at the intermediate focus 6. For example, the dynamic airlock assembly can be located between the radiation source SO and the illumination system IL.

[0118] EUV radiation incident on the membrane 100, 200, 300 heats it. This heating causes the temperature of the membrane 100, 200, 300 to rise. For example, the membrane 100, 200, 300 may reach temperatures of approximately 800°C to 900°C. Future EUV sources may have higher power and impose higher heat loads. If the temperature of the membrane 100, 200, 300 rises too much, the performance or lifespan of the membrane 100, 200, 300 may be reduced. The membrane 100, 200, 300 may even fail completely. It is desirable for the membrane 100, 200, 300 to have a combination of high emissivity for thermal regulation (i.e., increasing the rate at which the membrane can dissipate heat) and robust mechanical properties to reduce the likelihood of failure (e.g., fracture). It is also desirable for the membrane to have high EUV transmittance and high absorption of out-of-band wavelengths (e.g., DUV radiation and / or infrared radiation).

[0119] Figure 2 A side view of a diaphragm 400 according to the present disclosure is schematically depicted. Figure 2 The diaphragm 400 can be used as Figure 1 Any of the three membranes 100, 200, and 300 shown. The membrane 400 is configured to transmit EUV radiation. The membrane 400 includes a nanostructure configured to absorb DUV radiation. The nanostructure may include constituent elements (e.g., nanoparticles or particles and / or nanoscale particles or particles) having dimensions (e.g., diameters or lengths, such as major axis lengths) on the nanoscale (e.g., from about 1 nm to about 100 nm). The nanostructure may utilize one or more nanoscale absorption mechanisms, such as quantum confinement of radiation, plasmon excitation and / or formation of plasmon polaritons, metal-ligand charge transfer effects, and the like, to advantageously achieve equivalent or increased absorption of DUV radiation and / or infrared radiation at a membrane 400 that is thinner than known membranes. In this manner, the nanostructure can advantageously filter out equivalent or increased amounts of DUV radiation and / or infrared radiation while maintaining or increasing EUV transmission compared to known membranes.

[0120] The nanostructures may include semiconductor nanoparticles, such as silicon crystals. Each silicon crystal may be approximately 7 nm or less in size, for example, approximately 5 nm or less. The silicon crystals may be small enough to form silicon quantum dots. The average quantum dot size may be smaller than the radius of a Bohr exciton (i.e., a quasi-particle corresponding to a bound state of an electron-hole pair). As a result of quantum confinement of electromagnetic radiation, quantum dots advantageously provide enhanced and tunable optical properties. The nanostructures of the diaphragm 400, including quantum dots, are designed such that the size of the semiconductor nanoparticles is smaller than the Bohr exciton radius, thereby generating quantum confinement of the electron wave function. This causes the electronic structure of the nanoparticles to become size-dependent, thereby affecting the electronic and optical properties of the nanoparticles. In other words, the size of the quantum dots may be configured such that the quantum dots reside in the strong quantum confinement regime, rather than the intermediate or weak quantum confinement regime. The quantum dots are configured to absorb DUV radiation. By selecting the size and / or shape of the quantum dots, the discrete electron energy levels present in the quantum dots can be tailored to absorb DUV radiation.

[0121] The nanostructure of diaphragm 400 may include metallic nanoparticles, such as, for example, MoSi2 crystals or Ga crystals. For metallic nanoparticles, the collective interaction of their electrons with an external electromagnetic field (i.e., incident radiation) can induce localized surface plasmon polaritons, which are collective charge oscillations. The results of plasmon excitation include selective photon absorption, scattering, and / or emission at a resonant wavelength.

[0122] The nanostructure of the diaphragm 400 may include a matrix of semiconductor nanoparticles and metallic nanoparticles, such as, for example, Si crystals (e.g., Si quantum dots) and metallic nanoparticle MoSi2 crystals. The relative volume fraction of MoSi2 in the diaphragm 400 may be approximately 70% or more of the total volume fraction of MoSi2 and Si. The relative volume fraction of MoSi2 in the diaphragm 400 may be approximately 100% or less of the total volume fraction of MoSi2 and Si. The relative volume fraction of MoSi2 in the diaphragm 400 may increase as the thickness of the diaphragm 400 decreases.

[0123] The membrane 400 may also include nitrogen. For example, the membrane 400 may include trace or minute amounts of nitrogen. The nitrogen may be sandwiched between natural oxide shells that also contain trace amounts of nitrogen and naturally grow on the outer surface of the membrane 400. The trace amounts of nitrogen in the membrane 400 (including the natural oxide shells containing nitrogen) may total less than approximately 5 atomic percent. A membrane 400 including trace amounts of nitrogen may be referred to as a MoSiSi:N membrane. MoSiSi:N membranes 400 have been found to have an EUV radiation transmittance greater than approximately 95%. The presence of trace amounts of nitrogen in the MoSiSi:N membrane 400 also contributes to enhanced absorption of DUV radiation compared to known membranes. Alternatively, the membrane may include no trace amounts of nitrogen. A membrane including no trace amounts of nitrogen may be referred to as a MoSiN membrane. No trace amounts of nitrogen may advantageously increase the emissivity of the MoSiN membrane. This, in turn, may reduce or eliminate the need for an emissive layer (e.g., Ru and / or Mo), thereby improving the membrane's EUV radiation transmittance compared to known membranes.

[0124] The membrane 400 can have a thickness of about 8 nm or less, for example, about 5 nm or less. The membrane 400 is much thinner than known membranes, thereby advantageously improving the EUV radiation transmission of the membrane 400 compared to known membranes, while maintaining or improving other desirable properties compared to known membranes, such as increased absorption of DUV radiation and / or infrared radiation, increased emissivity for improved temperature regulation, sufficient mechanical strength at reduced membrane thickness, sufficient tension to reduce the risk of membrane sagging or breaking, etc.

[0125] The diaphragm 400 includes an unsupported portion 410. The unsupported portion 410 is held at its edges by a support structure 420. The diaphragm 400 can be produced, for example, using a mask to define the area of ​​the support structure 420 to be etched, and then etching the defined area. The support structure 420 can include a silicon wafer supporting the diaphragm 400. Etching the defined area can include removing a portion of the silicon wafer to release the unsupported portion 410 of the diaphragm 400. The support structure 420 can be considered as a frame for holding the unsupported portion 410 of the diaphragm 400. EUV radiation is transmitted through the unsupported portion 410 of the diaphragm 400 without experiencing any unwanted interaction with other structures (such as the support structure 420). As a result, a high level of EUV transmission is achieved.

[0126] Figure 3 Two scanning transmission electron microscope images of membranes formed according to the present disclosure are shown. Figure 3 The image on the left was taken at a first magnification and includes a distance scale indicating a distance of 50 nm. Figure 3 The image on the right was taken at a greater magnification than the first and includes a distance scale indicating a distance of 10 nm. Figure 3 The membrane includes silicon quantum dots 430 (ie, small black crystals), MoSi2 crystals 440 (ie, large gray crystals), and trace amounts of N (in Figure 3 The membrane has a thickness of about 8 nm. The membrane is annealed at 700 ° C. Figure 3 It can be seen that the MoSi2 metallized nanoparticles have a rounded morphology (e.g., spherical or at least partially spherical) and form a well-defined lattice. Figure 3 Not visible in.

[0127] Figure 4 DUV absorption of different membranes having nanostructures including MoSi2 crystals and Si crystals according to the present disclosure is shown. The membranes have different properties and / or different formation processes. The first membrane 450 has a thickness of 8 nm, includes trace amounts of N in the nanostructure, and is annealed at 700°C. The second membrane 451 has a thickness of 12 nm, includes trace amounts of N in the nanostructure, and is annealed at 700°C. The third membrane 452 has a thickness of 12 nm, includes trace amounts of N in the nanostructure, and is annealed at 900°C. The fourth membrane 453 has a thickness of 20 nm, includes trace amounts of N in the nanostructure, and is annealed at 900°C. The fifth membrane 454 has a thickness of 20 nm, does not include N in the nanostructure, and is annealed at 900°C. The sixth membrane 455 has a thickness of 30 nm, does not include N in the nanostructure, and is annealed at 900°C. The seventh diaphragm 456 has a thickness of 40 nm, does not include N in the nanostructure, and is annealed at a temperature of 900°C.

[0128] from Figure 4 As can be seen, thin membranes 450-453, which include trace amounts of N and have a thickness between about 8 nm and about 20 nm, provide superior optical absorption in the DUV region compared to thicker membranes 454-456, which do not include N in their nanostructures, for example, with a thickness between about 20 nm and about 40 nm. The absorption provided by membranes 450-456 is greater across the DUV region than thicker known membranes (e.g., having a thickness between about 30 nm and about 50 nm). This enhanced DUV absorption at smaller thicknesses is attributed to nanoscale absorption mechanisms implemented by the membrane's nanostructure, such as, for example, quantum confinement of radiation, plasmon excitation and / or formation of plasmon polaritons, metal-ligand charge transfer effects, and the like.

[0129] Figure 5 A side view of a first multilayer membrane 500 according to the present disclosure is schematically depicted. Figure 5 The diaphragm 500 can be used as Figure 1 Any of the three membranes 100, 200, 300 shown. The membrane 500 includes a core layer 510 and two cover layers 520, 530. At least one of the cover layers 520, 530 may be optional. For example, it is not necessary to include the cover layers 520, 530 to protect the core layer 510 from the scanning environment of the lithography equipment. The nanostructure of the membrane 500 exists in the core layer 510. Figure 5 In the example, the nanostructure comprises a MoSiSi:N membrane. That is, the core layer 510 comprises silicon crystals, MoSi2 crystals, and trace amounts of N. While the MoSiSi:N membrane 510 provides improved DUV absorption at a thinner thickness than known membranes, the use of a first capping layer 520 can improve the emissivity and / or infrared absorption of the membrane 500. Furthermore, the first capping layer 520 can shield the core layer 510 from the scanning environment of the lithographic apparatus.

[0130] The first capping layer 520 can include one or more elements configured to improve the emissivity and / or infrared absorption of the diaphragm 500. For example, the first capping layer 520 can include Ru and / or Mo. The first capping layer 520 can have a thickness of approximately 10 nm or less, such as approximately 9 nm, 8 nm, 7 nm, 6 nm, 5 nm, or 4 nm or less. The first capping layer 520 can have a thickness of approximately 3 nm or greater. The first capping layer 520 can have high emissivity in the infrared wavelength range. For example, where the emissivity varies between 0 (minimum) and 0.5 (maximum), the emissivity can be greater than 0.2, optionally greater than 0.3, and optionally greater than 0.4. Thus, the first capping layer 520 effectively dissipates heat and prevents the diaphragm 500 from overheating.

[0131] Figure 6 A side view of a second multilayer membrane 600 according to the present disclosure is schematically depicted. Figure 6 The diaphragm 600 can be used as Figure 1 Any of the three membranes 100, 200, 300 shown. The membrane 600 includes a core layer 610 and two cover layers 530 configured to protect the core layer 610 from the scanning environment of the lithographic equipment. At least one of the cover layers 530 may be optional. The nanostructure of the membrane 600 exists in the core layer 610. Figure 6 In the example of FIG, the nanostructure includes a MoSiN membrane 610. The core layer 610 includes silicon crystals. The core layer 610 includes MoSi2 crystals and / or Mo5Si3 crystals and / or Mo3Si crystals. The core layer 610 includes non-trace amounts of N. The presence of more N, Mo5Si3 crystals and / or Mo3Si crystals can improve the emissivity of the membrane 600. Similar to Figure 5The MoSiN membrane 600 provides improved DUV absorption at a lower thickness compared to known membranes. Figure 5 The presence of increased amounts of N and emissive Mo5Si3 crystals and / or Mo3Si crystals in core layer 610 improves the emissivity and / or infrared absorption of core layer 610 compared to core layer 510 of FIG. Figure 6 The diaphragm 600 does not include Figure 5 The first cover layer 520. Therefore, Figure 6 The total thickness of the diaphragm 600 may be less than Figure 5 The total thickness of the diaphragm 500. Figure 6 The diaphragm 600 can have a larger diameter than the Figure 5 The diaphragm 500 has greater EUV transmittance. Figure 6 The diaphragm 600 may not include the capping layer 530 , thereby further reducing its thickness and improving its EUV transmittance.

[0132] The materials used in the various layers of the multilayer diaphragm 500, 600 can meet various functional requirements. For example, the diaphragm 500 may include an emissivity layer 520 to increase thermal load resistance or tolerance. As another example, the diaphragm 500, 600 may include one or two outer capping layers 530 to protect the core layer 510, 610 from the harsh EUV scanning environment and increase the operational life of the diaphragm 500, 600. The outer capping layers 530 may include SiO2 and / or ZrO2. The outer capping layers 530 may form the outermost surface of the diaphragm 500, 600. The outer capping layers 530 may have a thickness of approximately 10 nm or less. For example, the outer capping layers 530 may have a thickness of approximately 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, or 2 nm or less. The outer capping layers 530 may have a thickness of approximately 1 nm or greater.

[0133] exist Figure 5 and Figure 6 In the two examples, the core layer 510, 610 can have a thickness of about 5 nm or less. When the thickness of the core layer reaches a very small thickness (e.g., 5 nm or less), the thickness of the core layer is significantly improved compared to the known diaphragms. Figure 2 、 Figure 5 and Figure 6Spectral analysis performed on the diaphragm shows an increase in DUV radiation absorption. This can be attributed to nanoscale absorption mechanisms such as, for example, quantum confinement of radiation, plasmon excitation and / or formation of plasmon polaritons, metal-ligand charge transfer effects, etc., depending on the constituent elements of the nanostructure. The core layer 510, 610 can have a thickness corresponding to the size of a single nanoparticle of the constituent elements forming the nanostructure. That is, the thickness of the core layer 510, 610 can correspond to a single grain of the nanostructure. For example, if the nanostructure includes silicon quantum dots having a diameter of 5 nm, the thickness of the core layer 510, 610 can also be 5 nm.

[0134] A method of forming a membrane according to the present disclosure includes forming a nanostructure configured to absorb deep ultraviolet radiation. Forming the nanostructure may include performing physical vapor deposition, such as sputtering deposition. Forming the nanostructure may include performing chemical vapor deposition, such as atomic layer deposition.

[0135] The composition of the membrane may be determined at least in part by the content of the sputtering target. Sputtering deposition may involve using a MoSiSi sputtering target. The MoSiSi sputtering target may include 15 atomic % or more Mo. The MoSiSI sputtering target may include 25 atomic % or less Mo.

[0136] Sputtering deposition can involve the use of two or more sputtering targets. For example, the first sputtering target can include Si, and the second sputtering target can include MoSi2. As another example, the first sputtering target can include a matrix material. The matrix material can include silicon or silicon nitride. As another example, the second sputtering target can include an inclusion material, such as one or more of molybdenum silicide, zirconium silicide, ruthenium silicide, and tungsten silicide.

[0137] The composition of the diaphragm can be determined, at least in part, by the power supplied to the sputtering target during the sputtering deposition process. That is, adjusting the power supplied to the sputtering target (e.g., bias voltage or RF power) can adjust the composition of the diaphragm formed as a result of the sputtering deposition process. The sputtering target can be supplied with a power of approximately 50 W or greater. The sputtering target can be supplied with a power of approximately 1000 W or less. The sputtering target can be supplied with a power of approximately 300 W or less. For example, sputtering deposition can involve using a sputtering target that includes an inclusion material (such as, for example, one or more of molybdenum silicide, zirconium silicide, ruthenium silicide, and tungsten silicide), and supplying a power of between approximately 50 W and approximately 300 W to the sputtering target to form a diaphragm that includes an inclusion material in an amount between approximately 10% and approximately 60% by volume, or between approximately 10% and 60% by volume, preferably between approximately 15% and approximately 50% by volume.

[0138] The method may include performing the deposition in the presence of N2. A flow of N2 may be provided to incorporate nitrogen into the diaphragm. Nitriding the metal silicide or silicon is achieved by sputtering the metal silicide or silicon substrate with a plasma. The sputtering may be reactive sputtering. The plasma may be any suitable plasma. The plasma preferably includes nitrogen. Preferably, the plasma includes a mixture of argon and nitrogen. Argon is included to provide an inert atmosphere. Argon is preferably used because it is less expensive than other noble gases, but other noble gases may also be used. The ratio of argon to nitrogen may vary. Having a greater proportion of nitrogen in the gas mixture will result in a greater amount of nitrogen being incorporated into the metal silicide film. The content of the sputtering target may at least partially determine the presence of nitrogen in the diaphragm. For example, the sputtering target may include a Mo content of approximately 20 atomic %, which has been found to result in trace amounts of nitrogen (e.g., less than approximately 5 atomic %) in the nanostructure of the diaphragm. As another example, a sputtering target can include a Mo content of about 22.5 atomic %, which has been found to produce non-trace amounts of N in the nanostructures (eg, greater than about 5 atomic % and less than about 20 atomic %).

[0139] Although specific reference may be made herein to the use of lithographic apparatus in the manufacture of integrated circuits, 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), pellicle heads, and the like.

[0140] Although embodiments of the present invention may be specifically referenced herein in the context of lithographic equipment, embodiments of the present invention may be used in other equipment. Embodiments of the present invention may form part of mask inspection equipment, metrology equipment, or any equipment that measures or processes objects such as wafers (or other substrates) or masks (or other patterning devices). These equipment are generally referred to as lithographic tools. Such lithographic tools may utilize either vacuum conditions or ambient (non-vacuum) conditions.

[0141] Where appropriate, 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 by instructions stored on a machine-readable medium, which can 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 read-only memory (ROM); random-access memory (RAM); magnetic storage media; optical storage media; flash memory devices; electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and the like. Furthermore, firmware, software, routines, and instructions may be described herein as performing certain actions. However, it should be understood that such descriptions are for convenience only and that these actions are in fact performed by a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc., and that the execution of such actions may cause actuators or other devices to interact with the physical world.

[0142] Although specific embodiments of the present invention have been described above, it should be understood that the present invention may be practiced in other ways than as described. The above description is intended to be illustrative rather than restrictive. Therefore, it will be clear to those skilled in the art that modifications may be made to the described invention without departing from the scope of the claims set forth below.

Claims

1. A membrane configured to transmit extreme ultraviolet radiation, the membrane comprising nanostructures configured to absorb deep ultraviolet radiation. The membrane of claim 1 , wherein the nanostructures comprise semiconductor nanoparticles. The membrane of claim 2 , wherein the semiconductor nanoparticles comprise silicon crystals. The diaphragm according to claim 3 , wherein the size of the silicon crystals is about 7 nm or less.

5. The membrane of any one of claims 2 to 4, wherein the semiconductor nanoparticles comprise quantum dots. The membrane of claim 5 , wherein the quantum dots comprise silicon quantum dots.

7. The membrane of any preceding claim, wherein the nanostructures comprise metallized nanoparticles.

8. The membrane of claim 7, wherein the metallized nanoparticles comprise MoSi2 crystals.

9. The membrane of claim 7, wherein the metallized nanoparticles comprise Mo5Si3 crystals and / or Mo3Si crystals.

10. The membrane of claim 7, wherein the metallic nanoparticles comprise Ga crystals.

11. The membrane of any preceding claim, wherein the nanostructure comprises a matrix of semiconductor nanoparticles and metallized nanoparticles.

12. The diaphragm of claim 11, wherein the semiconductor nanoparticles comprise Si crystals, and the metallized nanoparticles comprise at least one of MoSi2 crystals, Mo5Si3 crystals, and Mo3Si crystals.

13. The membrane according to any one of the preceding claims, comprising N. The membrane of claim 13 , comprising less than about 5 atomic % N.

15. The membrane of claim 13, comprising between about 5 atomic % and about 20 atomic % N.

16. The membrane of any preceding claim, having a thickness of about 8 nm or less.

17. The membrane according to any one of the preceding claims, wherein the membrane comprises a core layer and a cover layer, wherein the nanostructure is present in the core layer. The separator according to claim 17 , wherein the core layer has a thickness of about 5 nm or less.

19. The membrane according to claim 17 or 18, wherein the cover layer comprises SiO2 and / or ZrO2.

20. The membrane according to any one of claims 17 to 19, wherein the capping layer comprises Ru and / or Mo.

21. A membrane according to any preceding claim, comprising an unsupported portion.

22. A spectral purity filter for EUV lithography, comprising the membrane according to any one of claims 1 to 21.

23. A patterning device assembly for EUV lithography, the patterning device assembly comprising the membrane according to any one of claims 1 to 21.

24. A dynamic airlock assembly for EUV lithography, comprising the diaphragm according to any one of claims 1 to 21.

25. A lithographic system comprising the membrane according to any one of claims 1 to 21.

26. A method of forming a membrane configured to transmit extreme ultraviolet radiation, the method comprising forming nanostructures configured to absorb deep ultraviolet radiation.

27. The method of claim 26, wherein forming the nanostructure comprises physical vapor deposition or chemical vapor deposition.

28. The method of claim 27, wherein forming the nanostructure comprises sputter deposition using a sputter target.

29. The method of claim 28, wherein the sputtering target is a molybdenum silicide sputtering target comprising between about 15 atomic % and about 25 atomic % Mo.

30. The method of claim 28, comprising using a first sputtering target comprising Si and a second sputtering target comprising MoSi2.

31. The method of claim 28, comprising using a first sputtering target comprising a matrix material and a second sputtering target comprising an inclusion material, wherein the matrix material comprises silicon or silicon nitride, and The inclusion material includes one or more of molybdenum silicide, zirconium silicide, ruthenium silicide and tungsten silicide.

32. The method of any one of claims 28 to 31 , comprising adjusting the power supplied to the sputtering target to adjust the composition of the membrane.

33. The method of any one of claims 28 to 32, comprising providing between about 50 W and about 1000 W of power to the sputtering target.

34. The method of any one of claims 27 to 33, comprising performing the depositing in the presence of N2.

35. The method of claim 34, wherein the sputtering target comprises Mo and Si, and wherein the sputtering target comprises a Mo content of about 20 atomic %.

36. The method of claim 34, wherein the sputtering target comprises Mo and Si, and wherein the sputtering target comprises a Mo content of about 22.5 atomic %.

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