Pericle film for a lithographic apparatus

Abstract

A pellicle membrane for a lithographic apparatus is provided, the pellicle membrane comprising a matrix having a plurality of inclusions dispersed therein. Also provided are methods of making the pellicle membrane, a lithographic apparatus including the pellicle membrane, a pellicle assembly for use in a lithographic apparatus including the membrane, and the use of the pellicle membrane in a lithographic apparatus or method.

Description

Technical Field

[0001] Cross - reference to related applications

[0001] This application claims priority to European Patent Application No. 20152141.6 filed on January 16, 2020, European Patent Application No. 20179484.9 filed on June 11, 2020, and European Patent Application No. 20193717.4 filed on August 31, 2020, the entire contents of which are incorporated herein by reference.

[0002]

[0002] The present invention relates to a pellicle film for a lithographic apparatus, an assembly for a lithographic apparatus, and the use of a pellicle film in a lithographic apparatus or method.

Background Art

[0003]

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

[0004]

[0004] The minimum dimension of the features that can be formed on the substrate is determined by the wavelength of the radiation used by the lithographic apparatus to project the pattern onto the substrate. Using a lithographic apparatus that uses EUV radiation, which is electromagnetic radiation having a wavelength in the range of 4 - 20 nm, it may be possible to form smaller features on the substrate than with a conventional lithographic apparatus (which may use electromagnetic radiation having a wavelength of, for example, 193 nm).

[0005]

[0005] A lithographic apparatus includes a patterning device (e.g., a mask or reticle). Radiation is provided through or reflected from the patterning device in order to form an image on a substrate. A membrane assembly, also called a pellicle, may be provided to protect the patterning device from airborne particulate and other forms of contaminants. Contaminants on the surface of the patterning device may cause manufacturing defects on the substrate.

[0006]

[0006] A pellicle may also be provided to protect optical components other than the patterning device. A pellicle may also be used to provide a passage for lithographic radiation between regions of the lithographic apparatus that are sealed from each other. A pellicle may also be used as a filter, such as a spectral purity filter, or as part of a dynamic gas lock of the lithographic apparatus.

[0007]

[0007] A mask assembly may include a pellicle that protects the patterning device (e.g., a mask) from particulate contaminants. The pellicle may be supported by a pellicle frame to form a pellicle assembly. The pellicle may be attached to the frame, for example, by adhering or otherwise attaching the boundary region of the pellicle to the frame. The frame may be permanently or removably attached to the patterning device.

[0008]

[0008] The presence of a pellicle in the optical path of an EUV radiation beam requires the pellicle to have a high EUV transmittance. A higher EUV transmittance results in a greater proportion of the incident radiation passing through the pellicle. Further, when the amount of EUV radiation absorbed by the pellicle decreases, the operating temperature of the pellicle may decrease. Since the transmittance depends at least in part on the thickness of the pellicle, it is desirable to provide a pellicle that is as thin as possible while maintaining sufficient strength to withstand the sometimes harsh environment within the lithographic apparatus.

[0009]

[0009] Thus, it is desirable to provide a pellicle that can withstand the harsh environment of a lithographic apparatus, particularly an EUV lithographic apparatus. It is particularly desirable to provide a pellicle that can withstand higher power than conventional ones.

[0010]

[0010] This application generally refers to pellicles in the context of lithographic apparatuses, particularly EUV lithographic apparatuses, but the invention is not limited to pellicles and lithographic apparatuses only. It should be understood that the subject matter of the invention can be used in any other suitable apparatus or situation.

[0011]

[0011] For example, the method of the present invention may be similarly applied to a spectral purity filter. Some EUV radiation sources, such as those that use plasma to generate EUV radiation, emit not only the desired "in-band" EUV radiation but also unwanted (out-of-band) radiation. This out-of-band radiation is most prominent in the deep UV (DUV) radiation range (100 - 400 nm). Further, in the case of some EUV radiation sources, such as laser-produced plasma EUV radiation sources, radiation from a laser, which is typically 10.6 microns, causes significant out-of-band radiation.

[0012]

[0012] In a lithographic apparatus, spectral purity is desired for several reasons. One reason is that the resist is sensitive to out-of-band wavelengths of the radiation, and thus, when the resist is exposed to such out-of-band radiation, the image quality of the pattern applied to the resist may deteriorate. Further, infrared radiation of the out-of-band radiation, such as the 10.6-micron radiation in some laser-produced plasma radiation sources, causes unwanted and unnecessary heating of the patterning device, substrate, and optical components within the lithographic apparatus. Such heating can lead to damage to these elements, a reduction in their lifespan, and / or defects or distortions in the pattern projected onto and applied to the resist-coated substrate.

[0013]

[0013] A typical spectral purity filter may be formed from a silicon-based structure (e.g., a silicon lattice or other member with openings) coated with a reflective metal such as molybdenum. In use, a typical spectral purity filter may be exposed to, for example, a high thermal load from incident infrared and EUV radiation. Due to the thermal load, the temperature of the spectral purity filter may exceed 800 °C. Under a high head load, the coating may peel off due to the difference in the coefficient of linear expansion between the reflective molybdenum coating and the underlying silicon support structure. The peeling and deterioration of the silicon-based structure are accelerated by the presence of hydrogen, which is often used as a gas in the environment where the spectral purity filter is used to suppress the entry and exit of debris (e.g., debris such as particles) into a specific part of the lithographic apparatus. Therefore, a spectral purity filter may be used as a pellicle, and vice versa. Therefore, the reference to "pellicle" in this application is also a reference to "spectral purity filter". In this application, the reference is mainly to the pellicle, but all features equally apply to the spectral purity filter.

[0014]

[0014] The present invention has been devised in an attempt to address at least some of the problems identified above.

SUMMARY OF THE INVENTION

[0015]

[0015] According to a first aspect of the present invention, a pellicle film for a lithographic apparatus is provided, the film comprising a matrix in which a plurality of inclusions are dispersed internally.

[0016]

[0016] An inclusion is an individual region of a material different from the matrix material. The material of the inclusion and the matrix material may be chemically different. The material of the inclusion and the matrix material may have different forms.

[0017]

[0017] Inclusions may be in the form of crystals. Inclusions that can be crystals may be randomly dispersed. The inclusions may be amorphous, but are preferably crystalline.

[0018]

[0018] In this way, the pellicle film may be regarded as a composite material. Other pellicle films include layers of laminated materials. In other pellicle films, in order to increase the emissivity of the pellicle, an emissive metal layer is provided on the surface of the pellicle film. When the emissivity increases, the operating temperature of such a pellicle is reduced. Even so, such a pellicle is susceptible to the influence of island formation, which is the case where a thin metal layer de-wets from the underlying layer and forms discontinuous islands of metal. When islands are formed, the emissivity of the metal layer decreases, thereby increasing the operating temperature of the pellicle. The increase in the operating temperature leads to further de-wetting and island formation, and if this continues for too long, it may ultimately lead to defects in the pellicle. Once the metal layer has de-wetted from the pellicle film, it is necessary to replace the pellicle film. The present invention overcomes such problems by providing a plurality of inclusions, preferably in the form of crystals, within the matrix. Thus, the pellicle film according to the present invention is less susceptible to the influence of de-wetting and island formation.

[0019]

[0019] Crystals or inclusions may be randomly dispersed within the matrix. Since the crystals or inclusions are present to increase the emissivity of the film, there is no specific requirement that the crystals be uniformly distributed.

[0020]

[0020] The inclusions or crystals may contain a first material, and the matrix may contain a second material. Preferably, the emissivity of the first material is greater than the emissivity of the second material. In another embodiment, the emissivity of the second material is greater than the emissivity of the first material.

[0021]

[0021] Thus, the matrix and the inclusions / crystals may play different roles. The crystals may be made of a highly emissive material, particularly a material that is relatively more emissive than the matrix material. Thus, the crystals increase the overall emissivity of the pellicle film, thereby lowering the operating temperature of the pellicle film. As the emissivity becomes higher, the pellicle is less susceptible to the effects of overheating, which may enable the use of a higher power light source than that used in a lithographic apparatus. In the form of crystals dispersed within the matrix, having an emissive material, i.e., a material included in the pellicle film for the purpose of increasing the emissivity of the film, addresses the problems of dewetting and island formation. Further, due to the possibility of dewetting in a pellicle film including an emissive metal layer, the metal layer needs to be thick enough to reduce the possibility of island formation. Thus, the metal layer may be thicker than purely required from the perspective of emissivity. When the metal layer is thicker, the transmittance of the pellicle film decreases, thereby reducing the amount of light energy available for imaging and lowering the throughput of the lithographic apparatus. In the present invention, it is possible to include a smaller amount of the emissive material than was previously possible. Thus, the pellicle film according to the present invention can have a smaller amount of the emissive material compared to previous pellicle films. This has the advantage of increasing the transmittance of the pellicle film. The matrix material may be made of a material that can provide mechanical strength and structure to the pellicle film. The matrix material may have a lower emissivity than the crystals but may have greater mechanical strength. In this way, the composite material of the pellicle film of the present invention can have the mechanical strength required for use in a lithographic apparatus and a high emissivity for controlling the operating temperature of the film during use.

[0022]

[0022] The crystals or inclusions may include molybdenum silicide, zirconium silicide, ruthenium silicide, tungsten silicide, or combinations thereof.

[0023]

[0023] These materials have a high emissivity and can withstand the operating conditions of an EUV lithography apparatus. These materials have a high melting point and are conductive. The conductivity is proportional to the emissivity of the material.

[0024]

[0024] The matrix may contain silicon. Any allotrope or form of silicon may be used. For example, silicon may include polycrystalline silicon, amorphous silicon, nanocrystalline silicon, single-crystalline silicon, or combinations thereof. Silicon has good EUV transmittance. Silicon has a high etching selectivity with respect to silicon oxide, which is often used as a sacrificial layer during manufacturing. Furthermore, the thermal expansion coefficient of silicon, particularly p-Si, is close to that of the silicon substrate on which the pellicle film is manufactured. Therefore, the prestress level within the material can be more easily obtained.

[0025]

[0025] The matrix may contain silicon nitride. Silicon nitride has a low thermal expansion coefficient and a high melting point. Therefore, silicon nitride can withstand high temperatures and is suitable for use in a lithography apparatus. Also, silicon nitride has the mechanical strength necessary to withstand the conditions within an operating EUV lithography apparatus. Similarly, instead of or in addition to this, the matrix may contain silicon carbide.

[0026]

[0026] The membrane may not contain a metal coating. As described above, in certain pellicles, a metal layer is included to increase the emissivity of the pellicle, but such a membrane is in a high-energy state and is susceptible to dewetting and island formation. The present invention includes discontinuous portions of the emissive material throughout the matrix, and these discontinuous portions of the emissive material are not in a high-energy state. In use, the pellicle membrane is in the direct optical path of radiation such as EUV radiation used in a lithographic apparatus. In addition to operating at a low ambient pressure, this causes the membrane to reach a high temperature that may exceed 600 °C. This promotes chemical and structural degradation of the pellicle membrane, which may lead to a decrease in imaging performance or further defects in the pellicle. To lower the operating temperature of the pellicle, generally one or more emissive layers are included, which increase the emissivity of the pellicle and thereby lower the operating temperature of the pellicle at a given power. A continuous membrane pellicle with an emissive layer typically has an operating temperature in the range of 400 - 650 °C within an EUV lithographic apparatus with the power of the radiation source EUV in the range of 150 - 300 W (at intermediate focus), and higher temperatures may be expected for higher power radiation sources. Further, a capping layer may be provided to retard or prevent chemical degradation of the pellicle membrane. To maintain the acceptable transmittance and infrared (IR) emissivity of the pellicle, one or more emissive metal layers or conductive layers are made thin. However, a metal film deposited on an inert substrate is in an energetically unfavorable state. Heating a thin metal film applied on top of an inert (non-metallic) substrate may cause thermal instability at a temperature much lower than the melting point of the metal. Since sufficient activation energy is provided, this thin film forms holes through a surface diffusion process, and the holes grow with time at a rate strongly dependent on temperature. When the holes coalesce, the material on the surface forms islands of irregular shape. This process is called dewetting and island formation. By providing an adhesion layer between the metal film and the substrate, it is possible to reduce dewetting and island formation, but the metal film still remains in an energetically unfavorable state.Once the thin metal layer applied on the pellicle is divided into islands, it loses its high emissivity characteristics and thus becomes useless.

[0027]

[0027] The pellicle film may have a thickness of about 10 nm to about 50 nm. It will be understood that the thinner the film, the higher the transmittance, but the mechanically weaker it is than a thicker film.

[0028]

[0028] The pellicle film can be porous. Since there is no need to provide a closed layer, the film may be porous. One advantage of this is that the pressure difference across the pellicle film is reduced, thus reducing the possibility of deflection. Therefore, the minimum required level of prestress or residual stress is lower than that of the equivalent continuous film.

[0029]

[0029] The film may not include a plurality of laminated layers. In other pellicle films, there are a series of laminated layers such as a pellicle core and an emissive metal layer. These layers may peel off from each other during use, which is not desirable. Also, since these laminated layers need to be precisely arranged in a specific order, the manufacture of such pellicles can be time-consuming and complex. The present invention eliminates the need for a plurality of laminated layers, which can make the manufacture less time-consuming and less complex.

[0030]

[0030] Molybdenum, zirconium, tungsten, and / or ruthenium may be present in the pellicle film in an amount of about 2% to about 40% (atomic %), about 2% to about 30% (atomic %), about 2% to about 20% (atomic %), or about 5% to about 10% (atomic %). The emissivity of the pellicle film mainly depends on the amount of the emissive material (especially the material contained in the film to enhance the emissivity). When the amount of such a material is small, the emissivity is low. This was thought to lead to an increase in the operating temperature because the efficiency of the film for radiating the absorbed power is low. However, when the amount of the emissive material decreases, the transmittance of the pellicle increases, thereby reducing the amount of power absorbed.

[0031]

[0031] The film can be a pellicle core. Thus, one or more other layers may be provided to modify the properties of the film. The pellicle core may be attached to a frame to provide a pellicle assembly.

[0032]

[0032] The matrix material can be non-filamentous. Non-filamentous means that the matrix material is not in the form of filaments such as carbon nanotubes or nanotubes of other materials.

[0033]

[0033] The matrix material may not contain carbon. Thus, the matrix material can be a material other than carbon.

[0034]

[0034] According to a second aspect of the present invention, a method for manufacturing a pellicle film according to the first aspect of the present invention is provided. This method may include reactive physical vapor deposition or chemical vapor deposition. This method may include co-sputtering. This method may include sputtering from a single target having a composition with a given elemental ratio of target components to achieve better deposition uniformity across the deposition substrate.

[0035]

[0035] This method may further include annealing the steel. The annealing step may be performed at any suitable temperature. For example, annealing may be initiated at a temperature above 500 °C, above 600 °C, above 700 °C, or above 800 °C. Annealing gives the pellicle film its final density and forms crystals in the matrix. The difference between the thermal expansion coefficient of the pellicle film and the thermal expansion coefficient of the silicon substrate on which the pellicle film is formed results in the required level of prestress in the film. Annealing may be performed at a temperature up to 1200 °C, up to 1100 °C, up to 1000 °C, or up to 900 °C. It will be understood that higher annealing temperatures can be used if necessary.

[0036]

[0036] According to a third aspect of the present invention, a lithographic apparatus comprising a pellicle film according to the first aspect of the present invention is provided.

[0037]

[0037] According to a fourth aspect of the present invention, a pellicle assembly for use in a lithographic apparatus is provided, said pellicle assembly comprising a pellicle film according to the first aspect of the present invention.

[0038]

[0038] According to a fifth aspect of the present invention, the use of a pellicle film according to the first aspect in a lithographic apparatus or method is provided.

[0039]

[0039] According to a sixth aspect of the present invention, a method of controlling the composition of a pellicle film is provided, the method comprising providing first and second sputtering targets and adjusting the power supplied to one or both of the first and second sputtering targets to adjust the composition of the pellicle film.

[0040]

[0040] A pellicle film according to any aspect of the present invention can be manufactured using the method according to the sixth aspect of the present invention.

[0041]

[0041] Controlling the component ratio of a pellicle film is not straightforward. One possible method would be to deposit a multilayer structure of those components and then mix them during an annealing step. This method is limited by the thickness that can be deposited accurately and the amount of mixing of the individual layers during annealing. This can result in an insufficient level of stress in the final film, thereby preventing the use of the final film as a free-standing film.

[0042]

[0042] The method of the present invention enables better control of the composition of the pellicle film. By simultaneous sputtering of two materials and using different powers applied to the sputtering targets, it becomes possible to carefully adjust the final ratio of the matrix material to the inclusion material in the final pellicle film. In this way, an optimal balance between the transmittance and emissivity of the pellicle film can be achieved.

[0043]

[0043] The first sputtering target may contain a matrix material. The matrix material can be any matrix material described herein. Thus, the first sputtering target may contain silicon or silicon nitride. The matrix material gives physical strength to the pellicle film and also functions to support the inclusion material.

[0044]

[0044] The second sputtering target may contain an inclusion material. The inclusion material is preferably a material having a higher emissivity than the matrix material. The inclusion material can be any inclusion material described herein. Thus, the second sputtering target may contain molybdenum silicide, zirconium silicide, ruthenium silicide, tungsten silicide, or a combination thereof. The inclusion material functions to increase the emissivity of the pellicle film.

[0045]

[0045] It should be understood that by adjusting the relative powers applied to the first and second targets, the absolute magnitudes of the powers applied to each target may be the same or different. In order to increase the relative amount of one material in the final pellicle film, the power applied to each sputtering target may be increased. Of course, it should be understood that the relative powers applied to the first and second targets may be adjusted by keeping the power applied to one target the same and increasing or decreasing the power applied to the other target.

[0046]

[0046] If necessary, more than two types of sputtering targets can be used.

[0047]

[0047] This method includes a target power of 50 - 1000 W. Since the power applied to the target may be changed to adjust the composition of the final pellicle film, any suitable power may be used. The power is suitable if it is sufficient for the material to be sputtered and incorporated into the final pellicle film. If the power is too low, it may be insufficient to effectually sputter the material.

[0048]

[0048] This method may include providing a target power of 50 W to about 300 W to a second sputtering target to provide a pellicle film having a vol% of inclusion material of 10 to 60 vol%, preferably 15 to 50 vol%. It has been found that applying a power between 50 W and 300 W can produce a pellicle film having about 10 to about 60 vol% of sputtered material. Thus, according to any aspect of the present invention, the pellicle film may have a composition of about 10 to about 60 vol% inclusion material, preferably about 15 to about 50 vol% inclusion material. The remainder of the volume of the pellicle film may include a matrix material. In embodiments, the matrix material includes about 90 to about 40 vol% of the pellicle film. In embodiments, the matrix material includes about 90 vol%, about 80 vol%, about 70 vol%, about 60 vol%, about 50 vol%, or about 40 vol% of the pellicle film. The inclusion material may be present in a corresponding amount to balance the total volume of the pellicle film. In embodiments, the pellicle film has a minimum prestress of 100 MPa. The stress in the deposited layer by the method of the present invention or in the pellicle film according to any aspect of the present invention shows a linear dependence based on the amount of molybdenum included. In particular, when the pellicle film contains about 4 atomic% molybdenum, the stress in the pellicle film after annealing is about -200 MPa. At about 7.5 atomic% molybdenum, the stress in the pellicle film after annealing is about 100 MPa. With a greater amount of molybdenum, the stress becomes even greater. For example, at about 16 atomic% molybdenum, the stress after annealing is about 400 MPa, and at about 20 atomic% molybdenum, the stress after annealing is about 800 MPa.

[0049]

[0049] According to a seventh aspect of the present invention, there is provided a method of designing a film for a lithographic apparatus, the film being a matrix comprising a plurality of inclusions dispersed within the matrix, the matrix being characterized by output characteristics that depend at least in part on input characteristics, the method comprising receiving a set of input values associated with the input characteristics, and using semi-empirical thermodynamic modeling to generate a set of modeled films, each modeled film being modeled based on one of the set of input values associated with the input characteristics, predicting, based on the model, output values associated with the output characteristics of each of the set of modeled films, selecting one or more films from the set of modeled films based on the predicted output values, and outputting one or more input values from the set of input values based on the selected one or more films.

[0050]

[0050] Using this method, the characteristics of a pellicle film can be determined so as to optimize the output characteristics of the pellicle film for a given application. One or more films may be selected based on their predicted output values being determined to be optimal or acceptable. The output one or more input values are the values used to model the selected modeled film. The output one or more input values may be used as input values for a manufacturing process for manufacturing the film. Such a film may be referred to as an optimal film or an optimized film.

[0051]

[0051] Using this method, such a film can be virtually tested without the need to manufacture and test a series of films having different input characteristics. Advantageously, this method provides a way to design an optimal film at a significantly reduced cost and / or period compared to conventional methods. This method may be implemented on a computer.

[0052]

[0052] The semi-empirical thermodynamic modeling may include the CALPHAD (Calculation of Phase Diagrams) method.

[0053]

[0053] This method may further include validating one or more values using experimental data.

[0054]

[0054] The data may include empirically measured data. The data may include data from a catalog of measured properties. The values may be input values and / or output values. The values may include other values associated with the model, such as Gibbs energy.

[0055]

[0055] This method includes receiving a set of second input values associated with a second input characteristic, where the output characteristic is at least partially dependent on the second input characteristic, and outputting one or more second input values from the set of second input values based on one or more selected membranes, and each modeled membrane is further modeled based on a second input value among the set of second input values associated with the second input characteristic.

[0056]

[0056] That is, this method may include modeling a membrane based on multiple input characteristics.

[0057]

[0057] This method may further include predicting, based on the model, a second output value associated with each second output characteristic of a set of modeled membranes, where the second output characteristic is at least partially dependent on the input characteristic and / or the second input characteristic, and one or more membranes are further selected based on the predicted second output values.

[0058]

[0058] That is, this method may include determining multiple output characteristics of the membrane. The selected membrane may be selected based on optimal and / or acceptable values of the output value and the second output value.

[0059] Selecting one or more membranes may be based on either comparing the predicted output value of a first membrane of a set of modeled membranes to the predicted output value of a second membrane of the set of modeled membranes, or comparing the predicted output value of a first modeled membrane of a set of modeled membranes to a threshold value.

[0060] That is, a modeled membrane may be selected based on being considered to be better or more optimal compared to another modeled membrane. Alternatively, a modeled membrane may be selected based on exceeding a threshold value, e.g., a level of acceptability associated with the output value. In some cases, a modeled membrane may be selected only if it is considered to be better or more optimal compared to another modeled membrane and exceeds the threshold value.

[0061] The predicted output value may be an output value or a second output value. The comparison may include a determination of whether the predicted output value of the first membrane is greater than or less than the predicted output value of the second membrane. The threshold value may represent a desired value associated with an output characteristic, and exceeding this threshold value determines that a pellicle membrane having that output characteristic is desirable. The threshold value may represent an acceptable value associated with an output characteristic, and exceeding this threshold value determines that a pellicle membrane having that output characteristic is acceptable.

[0062] The input characteristic, and optionally a second input characteristic, may include one of matrix composition, inclusion concentration, inclusion composition, inclusion distribution, film thickness, film thickness variation, film porosity, amount of film prestress, manufacturing method, and characteristics associated with the manufacturing method, processing method, annealing temperature, annealing heating gradient, gas atmosphere. This list is not exhaustive, and other input characteristics may affect the output characteristics of the membrane, whether mentioned herein or elsewhere.

[0063]

[0063] The output characteristics, and optionally the second output characteristics, may include one of inclusion concentration, inclusion distribution, film thickness, film thickness variation, film porosity, amount of film prestress, film emissivity, film transmittance, film sensitivity. This list is not exhaustive, and other output characteristics may be used to characterize the film, whether or not mentioned elsewhere in this specification.

[0064]

[0064] This method may further include manufacturing the film using one or more output input values output, and optionally one or more second input values output. That is, the output values may be used as inputs to the manufacturing process.

[0065]

[0065] According to an eighth aspect of the invention, a pellicle film for a lithographic apparatus designed according to the method of the seventh aspect is described.

[0066]

[0066] According to a ninth aspect of the invention, a computer program is described that includes instructions operable to execute the method of the seventh aspect.

[0067]

[0067] According to a tenth aspect of the invention, a computer storage medium is described that includes the computer program of the ninth aspect.

[0068]

[0068] It will be understood that the features described with respect to one embodiment may be combined with any of the features described with respect to another embodiment, and all such combinations are expressly contemplated and disclosed herein.

[0069]

[0069] Here, embodiments of the invention will be described by way of example only with reference to the accompanying schematic drawings. In the drawings, corresponding reference numerals indicate corresponding parts.

Brief Description of the Drawings

[0070] [Figure 1]

[0070] A lithographic apparatus according to an embodiment of the invention is shown.

Best Mode for Carrying Out the Invention

[0071]

[0071] The features and advantages of the present invention will become more apparent when considering the following detailed description in conjunction with the drawings. In the drawings, like reference characters identify corresponding elements throughout. In the drawings, like reference numerals generally denote identical, functionally similar, and / or structurally similar elements.

[0072]

[0072] FIG. 1 shows a lithography system including a pellicle 15 (also called a membrane assembly) according to the present invention. This lithography system includes a radiation source SO and a lithography apparatus LA. The radiation source SO is configured to generate an extreme ultraviolet (EUV) radiation beam B. The lithography apparatus LA includes an illumination system IL, a support structure MT configured to support a patterning device MA (e.g., a mask), a projection system PS, and a substrate table WT configured to support a substrate W. The illumination system IL is configured to condition the radiation beam B before the radiation beam B is incident on the patterning device MA. The projection system is configured to project the radiation beam B (which is patterned by the mask MA at this point) onto the substrate W. The substrate W may include a previously formed pattern. If this is the case, the lithography apparatus aligns the patterned radiation beam B with the previously formed pattern on the substrate W. In this embodiment, the pellicle 15 is shown in the path of the radiation and protects the patterning device MA. It will be understood that the pellicle 15 may be placed at any required position and may be used to protect any of the mirrors within the lithography apparatus.

[0073]

[0073] The radiation source SO, the illumination system IL, and the projection system PS may all be constructed and arranged so as to be isolable from the external environment. In the radiation source SO, a gas at a pressure lower than atmospheric pressure (for example, hydrogen) may be provided. In the illumination system IL and / or the projection system PS, a vacuum may be provided. A small amount of gas (for example, hydrogen) at a pressure considerably lower than atmospheric pressure may be provided in the illumination system IL and / or the projection system PS.

[0074]

[0074] The radiation source SO shown in FIG. 1 is of a type that may be called a laser-produced plasma (LPP) radiation source. For example, a laser, such as a CO 2 laser that can be a laser is configured to deposit energy via a laser beam onto a fuel, such as tin (Sn) supplied from a fuel ejector. Although tin is mentioned in the following description, any suitable fuel can be used. The fuel may be, for example, in liquid form and can be, for example, a metal or an alloy. The fuel ejector may include a nozzle configured to direct tin, for example in the form of droplets, along a trajectory towards the plasma formation region. The laser beam is incident on the tin in the plasma formation region. Due to the deposition of laser energy on the tin, a plasma is generated in the plasma formation region. Radiation including EUV radiation is emitted from the plasma during the de-excitation and recombination of the ions of the plasma.

[0075]

[0075] The EUV radiation is collected and focused by a near-normal incidence radiation collector (more generally, sometimes also called a normal incidence radiation collector). The collector may have a multilayer structure configured to reflect EUV radiation (for example, EUV radiation having a desired wavelength such as 13.5 nm). The collector may have an elliptical configuration with two elliptical foci. As will be discussed below, the first focus may be in the plasma formation region and the second focus may be in an intermediate focus.

[0076]

[0076] The laser may be separated from the radiation source SO. If this is the case, the laser beam may be passed from the laser to the radiation source SO with the aid of a beam delivery system (not shown) comprising, for example, suitable guiding mirrors and / or beam expanders and / or other optical components. The laser and the radiation source SO may together be regarded as a radiation system.

[0077]

[0077] The radiation reflected by the collector forms a radiation beam B. The radiation beam B converges at a point to form an image of the plasma formation region, which acts as a virtual radiation source of the illumination system IL. The point at which the radiation beam B converges may be referred to as an intermediate focus. The radiation source SO is configured such that the intermediate focus is located at or near an opening within the sealed structure of the radiation source.

[0078]

[0078] The radiation beam B travels from the radiation source SO to an illumination system IL configured to condition the radiation beam. The illumination system IL may include a facet field mirror device 10 and a facet pupil mirror device 11. The facet field mirror device 10 and the facet pupil mirror device 11 together impart a desired cross-sectional shape and a desired angular distribution to the radiation beam B. The radiation beam B travels from the illumination system IL and is incident on a patterning device MA held by a support structure MT. The patterning device MA reflects the radiation beam B to impart a pattern. The illumination system IL may include other mirrors or devices in addition to or instead of the facet field mirror device 10 and the facet pupil mirror device 11.

[0079]

[0079] Following reflection from the patterning device MA, the patterned radiation beam B enters the projection system PS. The projection system includes a plurality of mirrors 13, 14 configured to project the radiation beam B onto a substrate W held by a substrate table WT. The projection system PS may apply a reduction factor to the radiation beam and form an image having features smaller than the corresponding features on the patterning device MA. For example, a reduction factor of 4 may be applied. The projection system PS has two mirrors 13, 14 in FIG. 1, but the projection system may include any number of mirrors (for example, six mirrors).

[0080]

[0080] The radiation source SO shown in FIG. 1 may include components not shown. For example, a spectral filter may be provided for the radiation source. The spectral filter may be substantially transmissive to EUV radiation but substantially blocking to radiation of other wavelengths such as infrared radiation.

[0081]

[0081] In one embodiment, the membrane assembly 15 is a pellicle for the patterning device MA of EUV lithography. The membrane assembly 15 of the present invention can be used for a dynamic gas lock, or a pellicle, or for another purpose. In one embodiment, the membrane assembly 15 includes a membrane formed from at least one membrane layer configured to transmit at least 90% of the incident EUV radiation. To ensure maximum EUV transmission and minimize the impact on imaging performance, the membrane is preferably supported only at the boundaries.

[0082]

[0082] When the patterning device MA is not protected, it may be necessary to clean or discard the patterning device MA due to contaminants. Cleaning the patterning device MA interrupts valuable manufacturing time, and discarding the patterning device MA is costly. Replacing the patterning device MA also interrupts valuable manufacturing time.

[0083]

[0083] In the method according to the sixth aspect of the present invention, the ratio (by atoms or mass) of the matrix material to the inclusion material may be adjusted by adjusting the power applied to the sputtering target containing the matrix material and / or by adjusting the power applied to the sputtering target. In the following description, reference is made to a silicon matrix and molybdenum silicide crystal inclusions, but this is merely an example, and it will be understood that any combination of matrix material and inclusion material described herein is equally applicable.

[0084]

[0084] Table 1 below shows the differences in the amount of molybdenum silicide in the pellicle film and how it depends on the power applied to the molybdenum silicide target.

[0085]

[0085] As can be seen from Table 1 below, by increasing the power applied to the molybdenum silicide target, it is possible to increase the density of the final pellicle film and also increase the vol% of molybdenum silicide in the pellicle film. The power applied to the silicon target is maintained, but it will be understood that in other embodiments of this method, the power of the silicon target may also be adjusted.

[0086]

Table 1

[0087] The film produced by co-sputtering may be subjected to further processing steps, including but not limited to annealing, if necessary. By the method of co-sputtering two target materials, it is possible to produce a deposited layer having a residual stress after annealing of less than 1 GPa. Therefore, such a film can function as a free-standing pellicle film. This has not been possible with other methods heretofore.

Examples

[0088]

[0086] The following examples provide specific embodiments of the invention. These examples are not intended to limit the scope of the invention.

[0089] Example 1 - MoSi crystals in an amorphous SiN matrix

[0087] This pellicle membrane is formed by decomposing MoSi 2 The film may be produced through reactive physical vapor deposition of a target. The film is then annealed at high temperatures, in particular at least above 700° C. The annealing may be performed at temperatures up to 1200° C., 1100° C., 1000° C., or 900° C. It will be understood that higher annealing temperatures can be used if necessary. The annealing step gives the film its final density, forming randomly distributed molybdenum silicide crystals within the SiN matrix. The SiN reduces the coefficient of thermal expansion (CTE) of the film, so that during the annealing step, there is a small difference in CTE between the film and the silicon substrate wafer on which it is formed. This provides the required amount of prestress in the film. The molybdenum silicide crystals provide the film with radiative properties that reduce the operating temperature of the pellicle film during use. In this way, a film having a thickness of less than 25 nm can be provided that has an EUV transmittance approaching 90% and can withstand exposure to EUV radiation, hydrogen plasma, and temperatures found in scanner conditions using a 600 W power supply. Alternatively, the pellicle film can be produced by co-sputtering a molybdenum silicide target and a silicon nitride target, with the power applied to each target being adjusted to change the relative proportions of silicon nitride and molybdenum silicide in the final film. As with pellicle films produced by reactive physical vapor deposition, there may be a subsequent annealing step.

[0090] Example 2 - MoSi crystals in a polycrystalline silicon (p-Si) matrix

[0088] This pellicle film may be manufactured by co-sputtering (physical vapor deposition using multiple targets) using targets of molybdenum and silicon. It will be understood that it is also possible to use a molybdenum silicide target and a silicon target. It will also be understood that it is possible to use a single target containing molybdenum and silicon in a given ratio. The power supplied to the target may be selected to result in a silicon-rich deposition. After annealing, the molybdenum forms molybdenum silicide, while the excess silicon forms p-Si, resulting in a composite material. Since p-Si is highly transmissive to EUV radiation, it is possible to increase the film thickness and make the film more physically robust while sacrificing slightly the EUV transmittance. In this way, a film with a thickness of about 20 nm and an EUV transmittance of more than 90% can be manufactured. Optionally, a slightly thicker film with a thickness of 40 nm and still having an EUV transmittance of about 90% can be produced. To prevent the bending of the pellicle film, a lower level of prestress is required for a thicker film.

[0091] Example 3 - MoSi crystals in SiC matrix The advantage of this combination is mainly EUV transmission. Carbon has a lower EUV absorption than nitrogen, and if all nitrogen is replaced by carbon, a merit of about 3% in EUVT over MoSiN should result.

[0092] Selection of film properties

[0089] The pellicle film may be characterized using several properties, such as matrix density, matrix composition, inclusion concentration (e.g., vol% in the matrix and / or relative concentration of the material in the inclusion), inclusion composition, inclusion distribution, film thickness, film thickness variation, film porosity, amount of film prestress, film emissivity, film transmittance, film sensitivity (e.g., sensitivity to temperature, pressure). The properties of the pellicle film may also affect external properties, such as the manufacturing method and properties related to that manufacturing method, such as the power applied to the sputtering target in a sputtering or co-sputtering method, annealing methods (e.g., electron beam annealing, rapid thermal annealing), and properties related to that annealing method, such as annealing temperature, annealing heating gradient, properties related to other processing steps, and the gas atmosphere in which the manufacturing annealing or other processing steps are performed. Annealing may be considered a processing step.

[0093]

[0090] Some properties referred to herein as input properties do not strongly depend on other properties. Input properties may be selected by the user as inputs to the manufacture of the pellicle film. That is, input properties are independent variables related to the manufacture of the pellicle film. Input properties may be referred to as independent variables. Examples of input properties are matrix composition, inclusion composition, and manufacturing method.

[0094]

[0091] In this specification, some characteristics referred to as output characteristics are at least partially dependent on other characteristics. That is, the output characteristics are dependent variables and may be so called. Thus, the output characteristics cannot be directly selected, but may be realized by selecting the input characteristics. The output characteristics may depend only on the input characteristics, only on other output characteristics, or on a combination of input and output characteristics. Examples of output characteristics are matrix density (which may depend at least on the power applied to the sputtering target), and pellicle transmittance (which may depend at least on matrix density, matrix composition, and film thickness). Output characteristics include characteristics of the film itself and may be called film characteristics.

[0095]

[0092] The input characteristics of the pellicle film can be selected to optimize the output characteristics of the pellicle film for a given application. Considering the wide range of characteristics and the range of values that each characteristic can take, it is not practical to manufacture a pellicle film for each combination of characteristics and their values. Instead, by modeling the characteristics of the film, it becomes possible to select the optimal set of characteristics for a given application. Using thermodynamic modeling, a wide range of pellicle films can be virtually tested. That is, the characteristics of the film may be determined without requiring the entire process of manufacturing and testing such a film. Such a process of manufacturing and testing the film can be costly and / or time-consuming (e.g., on the order of several months). As a result, manufacturing and testing films with different characteristics is even more costly and / or time-consuming. To determine the optimal set of characteristics for a given application at a significantly lower cost and / or period, a large solution space may be scanned by repeatedly performing virtual tests. The determination of the optimal set of characteristics of the film is sometimes called the design of the film.

[0096]

[0093] Thermodynamic modeling, particularly semi-empirical thermodynamic modeling, can be used. In semi-empirical methods, some experimental data are used to verify thermodynamic calculated values. The experimental data may include, for example, experimental data at a single point. Alternatively or in addition, the experimental data may include data from a catalog or database of measured properties of the material, such as data from a Gibbs energy database.

[0097]

[0094] In a specific example, the CALculation of PHAse Diagrams (CALPHAD) is used. The CALPHAD method models the properties of the components of a system and uses them to predict the properties of the whole system. The CALPHAD software package is available at https: / / gtt-technologies.de / .

[0098]

[0095] In an exemplary method, the input properties are scanned (i.e., the parameters associated with the input properties change regularly increasing from a first value to a second value), and the output parameters are predicted for each value of the input properties. For example, using the example of a pellicle film according to Example 2 above (including MoSi crystals in a polycrystalline silicon (p-Si) matrix), the temperature sensitivity of the pellicle is predicted for annealing temperatures in the range of 500 to 1000 °C. This model outputs data including the predicted temperature sensitivity for each annealing temperature to be tested. From the output data, an optimal temperature sensitivity (e.g., the lowest predicted temperature sensitivity) may be identified, and thus the optimal annealing temperature associated with that optimal temperature sensitivity is identified. Then, this optimal annealing temperature may be used in future manufacturing processes to produce a pellicle film with reduced temperature sensitivity.

[0099]

[0096] The above method is a single-input, single-output modeling method. In another method, multiple outputs may be predicted. For example, the model described above may output data including the predicted temperature sensitivity for each annealing temperature and the predicted pellicle film transmittance for each annealing temperature. That is, the output data is a multi-dimensional matrix of values. An optimal temperature sensitivity and / or an optimal transmittance may be identified, and thus one or more corresponding optimal annealing temperatures may be identified. One or more annealing temperatures may be identified that result in an acceptable temperature sensitivity and an acceptable transmittance. That is, a range of input values may be identified that result in an acceptable combination of output values.

[0100]

[0097] The above method is a single-input, multiple-output modeling method. In another example, multiple inputs may be used. For example, using the same example of a pellicle film according to Example 2, a range of values of a set of input characteristics, i.e., an annealing temperature in the range of 500 to 1000 °C, 1 °C s -1 ~5 °C s -1 heating rate in the range of, 1 °C s -1 ~5 °C s -1 cooling rate in the range of, and different gas environments (hydrogen, nitrogen), the temperature sensitivity of the pellicle is predicted. This model outputs data including the predicted temperature sensitivity for each combination of values of each input characteristic. That is, the output data is a multi-dimensional matrix of values. From the output data, an optimal temperature sensitivity (e.g., the lowest predicted temperature sensitivity) may be identified, and thus the optimal values of the set of input characteristics associated with that optimal temperature sensitivity may be identified.

[0101] Accordingly, a multiple-input, multiple-output modeling method may be used. For example, using the example of a capping film containing MoSiN (nitrogen-doped MoSi) crystals in a matrix, for a set of input characteristics, namely, doping method (e.g., co-sputtering, diffusion from a sacrificial layer, implantation) and dopant concentration (e.g., 0% - 5%), the temperature sensitivity and pressure sensitivity (e.g., gas pressure) are predicted. The output is a multi-dimensional matrix of values, from which an optimal set of input and output values, or an acceptable range of input and output values, may be identified.

[0102] By outputting the optimal input values, the output input values described above can be provided to the manufacturing process. For example, using the output input values described above, a film can be manufactured. In this way, an optimized film can be manufactured using the design process described above. Alternatively, the output input values and / or output values may be stored, or may be used as input to a future design process.

[0103] [000100] The modeling method (i.e., design process) described above is particularly useful in the following use cases.

[0104] [000101] Sensitivity analysis. Capping films are typically sensitive to temperature and / or gas pressure. By modeling capping films with various characteristics, one or more optimal sets of input characteristics can be identified that can be used to produce a capping film with optimized (i.e., reduced) sensitivity. In particular, the following input characteristics, namely, inclusion composition and dopant concentration (e.g., relative concentrations of N, Mo, and Si in a capping film containing MoSiN crystals in a matrix), annealing temperature, annealing gradient, annealing type, annealing atmosphere, capping film thickness, inclusion distribution, are input into the model (e.g., point defect engineering).

[0105] [000102] Identification of material combinations. Various materials can be used for inclusions and / or the matrix. Using modeling as described above, the optimal combination of materials can be identified. The optimal combination is determined based on one or more optimal output characteristics or an acceptable range of output characteristics, such as film permeability and / or stability characteristics. In particular, the following input characteristics, namely, inclusion composition (e.g., inclusion materials such as C, Si, Mo, Ru, N, O, B, Hf, Zr, Nb, Y and their relative concentrations), dopant concentration, manufacturing method, doping method, are input into the model.

[0106] [000103] Optimization of manufacturing methods. By modeling the characteristics of the pellicle film associated with a series of manufacturing methods and / or processing methods, manufacturing methods and processing methods (and their optimal characteristics) that optimize one or more characteristics of the pellicle film may be identified without physically manufacturing a large number of sets of pellicles. In particular, the following input characteristics, namely, manufacturing method, doping method, annealing method, annealing temperature, annealing gradient, gas atmosphere, are input into the model.

[0107] [000104] Considering the selection of optimal (or acceptable) characteristics, the optimal or acceptable characteristics may be determined in several ways. The optimal characteristics may be determined by comparing the sets of output characteristics predicted by that method and selecting the optimal (e.g., maximum or minimum) value. The optimal or acceptable characteristics may be determined by comparing the sets of output characteristics predicted by the model with a threshold value and selecting all predicted output characteristics that exceed the threshold value.

[0108] [000105] When referring to the prediction of output characteristics, it should be understood that the prediction can be the prediction of the value associated with the output characteristics. Similarly, for the provision or receipt of input characteristics, this may include the provision or receipt of the value associated with the input characteristics.

[0109] [000106] The modeling methods described in this specification may be implemented as instructions in a computer program. That is, the modeling methods may be implemented on a computer. Such a computer program may be stored on a computer storage medium.

[0110] [000107] Although this document may specifically refer to the use of a lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described in this specification may have other applications, such as in 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. The substrate referred to in this specification may be processed, for example, in a track (typically a tool for applying a resist layer to a substrate and developing the exposed resist), a metrology tool, and / or an inspection tool, before or after exposure. Where this is the case, the disclosure of this specification may be applicable to such and other substrate processing tools. Further, for example, in order to produce a multilayer IC, the substrate may be processed multiple times, and as a result, the term substrate as used in this specification may also refer to a substrate that already includes a plurality of processed layers.

[0111] [000108] Although specific embodiments of the present invention have been described above, it will be understood that the present invention may be implemented in other ways different from those described.

[0112] [000109] The above description is intended to be illustrative rather than limiting. Accordingly, it will be apparent to those skilled in the art that modifications can be made to the present invention as described, without departing from the scope of the claims set forth below. and clauses from departing therefrom. [Clause 1] A pellicle film for a lithographic apparatus, the pellicle film comprising a matrix in which a plurality of inclusions are dispersed. [Clause 2] The pellicle film according to clause 1, wherein the plurality of inclusions include a plurality of crystals, and optionally the crystals are randomly dispersed. [Clause 3] The pellicle film according to clause 1 or clause 2, wherein the inclusion or the crystal includes a first material, the matrix includes a second material, and the emissivity of the first material is greater than the emissivity of the second material. [Clause 4] The pellicle film according to any one of clauses 1 to 3, wherein the inclusion or the crystal includes molybdenum silicide, zirconium silicide, ruthenium silicide, tungsten silicide, or a combination thereof. [Clause 5] The pellicle film according to any one of clauses 1 to 4, wherein the matrix includes silicon. [Clause 6] The pellicle film according to clause 5, wherein the matrix includes silicon nitride and / or silicon carbide. [Clause 7] The pellicle film according to clause 5, wherein the silicon may include any one of p-Si, a-Si, nc-Si, mono-Si, or a combination thereof. [Clause 8] The pellicle film according to any one of clauses 1 to 7, wherein the film does not include a metal coating. [Clause 9] The pellicle film according to any one of clauses 1 to 8, wherein the film has a thickness of about 10 nm to about 50 nm. [Clause 10] The pellicle film according to any one of clauses 1 to 9, wherein the film is porous. [Clause 11] The pellicle film according to any one of clauses 1 to 10, wherein the film does not include a plurality of laminated layers. [Clause 12] The molybdenum, the zirconium, the tungsten, and / or the ruthenium are present in the pellicle film in an amount of about 2% to about 40%, about 2% to about 30%, about 2% to about 30%, or 5% to about 10% (atomic %), or the pellicle film has a composition of about 10 to about 60 vol% of inclusion material, preferably about 15 to about 50 vol% of inclusion material, the pellicle film according to any one of clauses 1 to 11 subordinate to clause 4. [Clause 13] The pellicle film according to any one of clauses 1 to 12, wherein the film includes a pellicle core. [Clause 14] The pellicle film according to any one of clauses 1 to 13, wherein the matrix material is non-filamentous. [Clause 15] The pellicle film according to any one of clauses 1 to 14, wherein the matrix material does not include carbon. [Clause 16] A method for manufacturing a pellicle film according to any one of clauses 1 to 15, the method including reactive physical vapor deposition, chemical vapor deposition, or co-sputtering. [Clause 17] The method according to clause 16, further including an annealing step. [Clause 18] A lithography apparatus including a pellicle film according to any one of clauses 1 to 15. [Clause 19] A pellicle assembly for use in a lithography apparatus, the pellicle assembly including a pellicle film according to any one of clauses 1 to 15. [Clause 20] Use of a pellicle film according to any one of clauses 1 to 15 in a lithography apparatus or method. [Clause 21] A method for controlling the composition of a pellicle film, the method including providing a sputtering target and adjusting power to adjust the composition of the pellicle film. [Clause 22] The method according to clause 21, including providing first and second sputtering targets and adjusting the power supplied to one or both of the first and second sputtering targets to adjust the composition of the pellicle film. [Clause 23] The first sputtering target includes a matrix material, and preferably, the matrix material includes silicon or silicon nitride, according to the method of clause 22. [Clause 24] The second sputtering target includes an inclusion material, and preferably, the inclusion material includes molybdenum silicide, zirconium silicide, ruthenium silicide, tungsten silicide, or a combination thereof, according to the method of clause 22 or clause 23. [Clause 25] The method according to any one of clauses 22 to 24, in which more than two sputtering targets are used. [Clause 26] The method according to any one of clauses 21 to 25, including a target power of 50 to 1000 W. [Clause 27] The method according to any one of clauses 21 to 26, including providing a target power of 50 W to about 300 W to the second sputtering target to provide a pellicle film having a vol% of the inclusion material of 10 to 60 vol%, preferably 15 to 50 vol%. [Clause 28] A method of designing a film for a lithographic apparatus, said film being a matrix comprising a plurality of inclusions dispersed within the matrix, said matrix comprising a matrix characterized by output characteristics that depend at least in part on input characteristics, said method comprising: Receiving a set of input values associated with said input characteristics; Generating a set of modeled films using semi-empirical thermodynamic modeling, each modeled film being modeled based on a certain input value of said set of input values associated with said input characteristics; Predicting output values associated with respective ones of said output characteristics of said set of modeled films based on said model; Selecting one or more films from said set of modeled films based on said predicted output values; Outputting one or more input values from said set of input values based on said selected one or more films. A method comprising. [Article 29] The semi-empirical thermodynamic modeling is the method according to Article 28, including the CALPHAD (Calculation of Phase Diagrams) method. [Article 30] The method according to Article 28 or 29, further comprising verifying one or more values using experimental data. [Article 31] Receiving a set of second input values associated with second input characteristics, said output characteristics depending at least in part on said second input characteristics; Outputting one or more second input values from said set of second input values based on said selected one or more films; further comprising, Each modeled film is further modeled based on a certain second input value of said set of second input values associated with said second input characteristics. The method according to any one of Articles 28 to 30. [Article 32] Predicting second output values associated with respective second output characteristics of said set of modeled films based on said model, said second output characteristics depending at least in part on said input characteristics and / or second input characteristics; further comprising, Said one or more films are further selected based on said predicted second output values. The method according to any one of Articles 28 to 31. [Article 33] Said selecting one or more films comprises Comparing the predicted output value of the first membrane of the set of modeled membranes with the predicted output value of the second membrane of the set of modeled membranes, and / or, Based on comparing the predicted output value of the first modeled membrane of the set of modeled membranes with a threshold value, the method according to any one of clauses 28 to 32. [Clause 34] The input characteristics, and optionally the second input characteristics, are a matrix composition, an inclusion concentration, an inclusion composition, an inclusion distribution, a film thickness, a film thickness variation, a film porosity, an amount of film prestress, a manufacturing method, and characteristics associated with the manufacturing method, a processing method, an annealing temperature, an annealing heating gradient, a gas atmosphere, and include one of those according to any one of clauses 28 to 33, the method according to any one of clauses 28 to 33. [Clause 35] The output characteristics, and optionally the second output characteristics, are an inclusion concentration, an inclusion distribution, a film thickness, a film thickness variation, a film porosity, an amount of film prestress, a film emissivity, a film transmittance, a film sensitivity, and include one of those according to any one of clauses 28 to 34, the method according to any one of clauses 28 to 34. [Clause 36] Further comprising manufacturing a membrane using the output one or more input values, and optionally the output one or more second input values, according to any one of clauses 28 to 35, the method according to any one of clauses 28 to 35. [Clause 37] A pellicle film for a lithographic apparatus designed according to any one of clauses 28 to 36. [Clause 38] A computer program comprising instructions operable to perform the method according to any one of clauses 28 to 36. [Clause 39] A computer storage medium comprising the computer program according to clause 38.

Claims

1. A pellicle film for a lithographic apparatus, comprising a matrix in which a plurality of inclusions are dispersed, the plurality of inclusions including a plurality of crystals, the film having a thickness of 50 nm or less and not including a plurality of stacked layers.

2. The pellicle film according to claim 1, wherein the crystals are randomly dispersed.

3. The pellicle film according to claim 1 or claim 2, wherein the inclusion contains a first material, the matrix contains a second material, and the emissivity of the first material is greater than the emissivity of the second material.

4. The pellicle film according to any one of claims 1 to 3, wherein the inclusion contains molybdenum silicide, zirconium silicide, ruthenium silicide, tungsten silicide, or a combination thereof.

5. The pellicle film according to any one of claims 1 to 4, wherein the matrix contains silicon.

6. The pellicle film according to claim 5, wherein the matrix contains silicon nitride and / or silicon carbide.

7. The pellicle film according to claim 5, wherein the silicon contains any one of p-Si, a-Si, nc-Si, mono-Si, or a combination thereof.

8. The pellicle film according to any one of claims 1 to 7, wherein the film does not include a metal coating, and / or the matrix material does not contain carbon, and / or the film does not include a plurality of stacked layers.

9. The molybdenum, the zirconium, the tungsten, and / or the ruthenium is present in the pellicle film in an amount of about 2% to about 40%, about 2% to about 30%, about 2% to about 30%, or 5% to about 10% (atomic %), or the pellicle film has a composition of about 10 to about 60 vol% inclusion material, preferably about 15 to about 50 vol% inclusion material. The pellicle film according to any one of claims 5 to 8 dependent on claim 4.

10. A pellicle film for a lithographic apparatus, comprising a matrix in which a plurality of inclusions are dispersed, the matrix being polycrystalline silicon or silicon carbide, and the plurality of inclusions dispersed therein including molybdenum silicide crystals.

11. The pellicle film according to claim 1 or claim 10, wherein the film is doped with a dopant at a concentration of 0% to 5%.

12. A pellicle assembly for use in a lithographic apparatus, the pellicle assembly comprising a pellicle film according to any one of claims 1 to 11. **Claim 13** A method of controlling the composition of a pellicle film according to any one of claims 1 to 11, the method comprising: providing a first sputtering target comprising a matrix material and a second sputtering target comprising an inclusion material; and adjusting the power supplied to one or both of the first and second sputtering targets to adjust the composition of the pellicle film. **Claim 14** The method according to claim 13, wherein the matrix material comprises silicon or silicon nitride. **Claim 15** The method according to claim 13 or claim 14, wherein the inclusion material comprises molybdenum silicide, zirconium silicide, ruthenium silicide, tungsten silicide, or a combination thereof. **Claim 16** The method according to claim 15, comprising providing a target power of 50 W to about 300 W to the second sputtering target to provide a pellicle film having a vol% of the inclusion material of 10 to 60 vol%, preferably 15 to 50 vol%.

Images