Target material containment and transport system for EUV radiation sources.

Abstract

An apparatus adapted to transport a molten target material, such as tin, that is irradiated and converted in an extreme ultraviolet radiation source is disclosed, wherein a component of such a system that is exposed to the molten target material under pressure (such as a filter housing through which the molten target material passes) comprises an alloy of two high-melting point metals, e.g., molybdenum and rhenium.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Application No. 63 / 446,712, entitled "Target Material Storage and Transport System for EUV Radiation Sources," filed February 17, 2023, the entire contents of which are incorporated herein by reference.

[0002] FIELD OF THE DISCLOSURE

[0002] This disclosure relates to extreme ultraviolet (EUV) radiation sources that generate EUV radiation by converting a target material, and in particular to devices and systems for storing and transporting the target material. [Background technology]

[0003]

[0003] EUV radiation, for example, electromagnetic radiation having a wavelength of approximately 50 nm or less (sometimes called soft x-rays) and including light with a wavelength of about 13 nm, is used in photolithography processes to create extremely small features in and on substrates, such as silicon wafers.

[0004]

[0004] Methods for generating EUV radiation include, but are not limited to, methods that generate radiation by first converting the physical state of a target material into a plasma state. The plasma is typically generated in a sealed vessel, such as a vacuum chamber, and monitored using various types of metrology equipment. The target material includes elements that have emission lines in the EUV range, such as xenon, lithium, or tin. The target material may be solid, liquid, or gaseous immediately before being introduced into the vacuum chamber.

[0005] In one known method involving a liquid target material, the necessary plasma is generated by irradiating droplets or clusters of the target material with a drive laser. One technique for generating droplets involves melting a solid target material and then feeding the liquid target material into a target material delivery system, also known as a droplet generator. The target material delivery system forces the liquid target material under high pressure through a relatively small orifice, such as an orifice having a diameter of about 0.5 μm to about 30 μm, to generate a stream of droplets. The droplet generator directs the droplets to the primary focus of a collector optic, where at least some of the droplets are individually irradiated to generate EUV light.

[0006] In some systems, the target material delivery system includes one or more reservoirs that keep the target material ready to be delivered to the droplet generator, the interior of which is maintained under pressure to force the flow of liquid target material from the reservoir to the droplet generator.

[0007]

[0007] As mentioned above, tin is one suitable choice for the target material. However, molten tin at high temperatures is extremely corrosive. Therefore, components of tin containment and delivery systems have traditionally been made from materials that can withstand prolonged exposure to molten tin under pressure. Molybdenum (Mo) is a relatively strong material that can withstand corrosion from exposure to molten tin, and is therefore the recommended material of choice for this application.

[0008] Higher EUV power output at higher repetition rates requires faster droplets with greater droplet spacing. Acceleration of droplets produced by droplet generators has been achieved to date by increasing the pressure of the driving gas. Currently, droplet velocities of approximately 80 m / s are achieved using pressures of approximately 4000 psi (270 bar). Future EUV designs will need to achieve much higher droplet velocities, requiring driving pressures of up to 20305 psi (1400 bar). The need to use these higher pressures necessitates the use of materials that exhibit higher tensile strengths than materials such as pure molybdenum.

[0009]

[0009] It is in these circumstances that the need and advantages of the presently disclosed subject matter arise. Summary of the Invention

[0010] The following is a brief summary intended to provide a basic understanding of embodiments. This summary is not intended to be an exhaustive overview of all contemplated embodiments, nor is it intended to identify key or critical elements of any embodiment. Its sole purpose is to present some concepts related to one or more embodiments as a prelude to the more detailed description that is presented later.

[0011]

[0011] According to one aspect of an embodiment, a target material storage and transport system adapted to transport target material to an irradiation site within an extreme ultraviolet radiation source may be disclosed, the target material storage and transport system including a filter arranged so that the target material passes through the filter as it passes through the target material storage and transport system, the filter including a filter housing, the filter housing including an alloy of a first high melting point metal and a second high melting point metal.

[0012]

[0012] The first refractory metal can be ruthenium. The weight percentage of ruthenium in the alloy can be in the range of 5 wt% to about 50 wt%. The second refractory metal can be molybdenum.

[0013] The weight percent of ruthenium in the alloy can be in the range of 5% to about 50% by weight, with the remainder being molybdenum in addition to impurities normally present. The weight percent of ruthenium in the alloy can be about 47.5% by weight, with the remainder being molybdenum in addition to impurities normally present.

[0014] The second refractory metal can be tantalum. The weight percent of ruthenium in the alloy can be in the range of 5% to about 50% by weight, with the remainder being tantalum in addition to impurities normally present. The weight percent of ruthenium in the alloy can be about 47.5% by weight, with the remainder being tantalum in addition to impurities normally present.

[0015]

[0015] According to another aspect of the embodiment, a molten tin containment and transport system is disclosed that includes at least one component that contacts pressurized molten tin, the component including an alloy consisting of a first high melting point metal and a second high melting point metal.

[0016]

[0016] The first refractory metal can be ruthenium. The weight percent of ruthenium in the alloy can be in the range of 5% to about 50% by weight. The second refractory metal can be molybdenum. The weight percent of ruthenium in the alloy can be in the range of 5% to about 50% by weight, with the remainder being molybdenum in addition to impurities normally present. The weight percent of ruthenium in the alloy can be about 47.5% by weight, with the remainder being molybdenum in addition to impurities normally present.

[0017] The second refractory metal can be tantalum. The weight percent of ruthenium in the alloy can be in the range of 5% to about 50% by weight, with the remainder being tantalum in addition to impurities normally present. The weight percent of ruthenium in the alloy can be about 47.5% by weight, with the remainder being tantalum in addition to impurities normally present.

[0018]

[0018] According to another aspect of the embodiment, a radiation source of extreme ultraviolet radiation for semiconductor photolithography is disclosed, the radiation source comprising: a vacuum chamber; a collector optic disposed within the vacuum chamber and having a focal point within the chamber; a target material storage and transport system arranged to distribute droplets of target material at the focal point within the chamber to an irradiation site, the target material storage and transport system including a filter disposed such that the target material passes through the filter as it passes through the target material storage and transport system, the filter including a filter housing, the filter housing including an alloy of a first high melting point metal and a second high melting point metal.

[0019]

[0019] The first refractory metal can be ruthenium. The weight percent of ruthenium in the alloy can be in the range of 5% to about 50% by weight. The second refractory metal is molybdenum. The weight percent of ruthenium in the alloy can be in the range of 5% to about 50% by weight, with the remainder being molybdenum in addition to impurities normally present. The weight percent of ruthenium in the alloy can be about 47.5% by weight, with the remainder being molybdenum in addition to impurities normally present.

[0020] The second refractory metal can be tantalum. The weight percent of ruthenium in the alloy can be in the range of 5% to about 50% by weight, with the remainder being tantalum in addition to impurities normally present. The weight percent of ruthenium in the alloy can be about 47.5% by weight, with the remainder being tantalum in addition to impurities normally present.

[0021] According to another aspect of the embodiment, a filter for a target material containment and transport system adapted to transport target material to an irradiation site within an extreme ultraviolet radiation source is disclosed, the filter including a filter housing containing an alloy of a first refractory metal and a second refractory metal. The first refractory metal can be ruthenium. The weight percent of ruthenium in the alloy can be in the range of 5% to about 50% by weight. The second refractory metal can be molybdenum. The weight percent of ruthenium in the alloy can be in the range of 5% to about 50% by weight, with the remainder being molybdenum in addition to impurities normally present. The weight percent of ruthenium in the alloy can be about 47.5% by weight, with the remainder being molybdenum in addition to impurities normally present.

[0022] The second refractory metal can be tantalum. The weight percent of ruthenium in the alloy can be in the range of 5% to about 50% by weight, with the remainder being tantalum in addition to impurities normally present. The weight percent of ruthenium in the alloy can be about 47.5% by weight, with the remainder being tantalum in addition to impurities normally present.

[0023]

[0023] A source of extreme ultraviolet radiation for semiconductor photolithography is disclosed, comprising a vacuum chamber and a tin containment and transport system arranged to distribute droplets of molten tin to an irradiation site within the chamber, the tin containment and transport system including a filter arranged to remove particulate contaminants from the molten tin passing through the tin containment and transport system, the filter including a filter housing containing an alloy of a first high melting point metal and a second high melting point metal.

[0024] Further embodiments, features, and advantages of the subject matter of the present disclosure, as well as the structure and operation of the various embodiments, are described in detail below with reference to the accompanying drawings. [Brief explanation of the drawings]

[0025]

[0025] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate the presently disclosed subject matter and, together with the specification, serve to further explain the principles of the presently disclosed subject matter and to enable one skilled in the relevant art to make and use the presently disclosed subject matter.

[0026] [Figure 1]

[0026] FIG. 1 is a partially schematic functional block diagram illustrating the overall broad concept of a laser-produced plasma EUV radiation source in which aspects of an embodiment may be embodied. [Figure 2]

[0027] 2 is a schematic cross-sectional view illustrating an exemplary target material supply apparatus that may be used in the EUV radiation source of FIG. 1. [Figure 3]

[0028] 1 is a cross-section of a target material filter according to an aspect of an embodiment. [Figure 4]

[0029] 1 is a schematic cross-sectional view showing a structure around a capillary nozzle having a filter in a system according to one aspect of an embodiment.

[0027]

[0030] Further features and advantages of the disclosed device, as well as the structure and operation of various embodiments of the disclosed device, are described in detail below with reference to the accompanying drawings. The disclosed device is not limited to the specific embodiments described herein. Such embodiments are shown herein for illustrative purposes only. Additional embodiments will be apparent to those skilled in the art based on the teachings herein. DETAILED DESCRIPTION OF THE INVENTION

[0028]

[0031] Various embodiments are now described with reference to the drawings, wherein like reference numerals are used to refer to like components throughout the specification. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. However, it will be apparent that in some or all cases, any of the embodiments described below can be practiced without employing the specific design details described below.

[0029]

[0032] In the following description and claims, terms such as "up," "down," "upper," "lower," "top," "bottom," "vertical," "horizontal," etc. are used, and unless otherwise indicated or clear from the context, these terms are intended to indicate a relative orientation only and not an absolute orientation, such as with respect to gravity.

[0030]

[0033] 1 is a schematic diagram of an example of an EUV radiation source, e.g., a laser-produced plasma EUV radiation source 10. As shown, EUV radiation source 10 may include a pulsed or continuous laser source 15, such as a pulsed gas discharge CO2 laser source that produces a beam 17 of pulses of radiation, typically at a wavelength less than 20 μm, e.g., in the range of about 11 μm to about 9 μm or less. The pulsed gas discharge CO2 laser source may have DC or RF excitation operating at high power and high pulse repetition rates.

[0031]

[0034] The EUV radiation source 10 also includes a target material delivery system 20 for delivering target material in the form of droplets or a continuous liquid stream. In this example, the target material is liquid, but it could also be solid. The target material may be comprised of tin or a tin compound, although other materials may also be used. In the illustrated system, the target material delivery system 20 introduces droplets 25 of the target material to an irradiation region 32 within a vacuum chamber 30, where the droplets 25 can be irradiated to generate a plasma. Note that, as used herein, an irradiation region refers to the region where irradiation of the target material occurs, even if no irradiation is actually occurring. The EUV light source 10 also includes a beam focusing and steering system 35.

[0032]

[0035] In the illustrated example, the components are arranged so that droplet 25 moves substantially horizontally with respect to gravity. The direction from laser source 15 toward irradiation area 32, i.e., the nominal direction of propagation of beam 17, may be considered the Z-axis. The path that droplet 25 follows from target material transport system 20 to irradiation area 32 may be considered the X-axis. The perspective of FIG. 1 is therefore perpendicular to the XZ plane. Also, while a system is depicted in which droplet 25 moves substantially horizontally, one skilled in the art will understand that other configurations in which droplet 25 moves at angles between 90 degrees (horizontal) and 0 degrees (vertical) with respect to gravity may be used.

[0033]

[0036] The EUV radiation source 10 may also include an EUV light source controller system 40 and a laser firing control system 45, along with a beam steering system 35. The EUV radiation source 10 may also include a detector, such as a target position detection system, which may include, for example, one or more droplet imagers 50 that generate an output indicative of the absolute or relative position of the target droplets with respect to the irradiation area 32 and provide this output to a target position detection feedback system 55. The target position detection feedback system 55 may use the output of the droplet imager 50 to calculate the target position and target trajectory, from which a target error can be calculated.

[0034]

[0037] The EUV radiation source 10 shown in FIG. 1 also includes a conditioning laser 60 for generating a conditioning beam 62. The conditioning beam 62 is comprised of pulses that prepare a target for subsequent heating by a main drive pulse. The conditioning pulses can change the shape and profile of the target. Such conditioning pulses include various pulses referred to as pre-pulses, pedestal pulses, and rarefaction pulses. The laser beam steering system 35 can steer the conditioning beam 62 generated by the conditioning laser 60.

[0035]

[0038] 1, the target material transport system 20 may include a target transport control system 70. The target transport control system 70 operates in response to a signal, such as a target error or some quantity derived from the target error, provided by the system controller 40, to adjust the path of the target 25 through the irradiation region 32. This may be accomplished, for example, by repositioning the point at which the target transport mechanism 72 releases droplets 25 from the capillary 75. The droplet release point of the capillary 75 may be repositioned, for example, by tilting or moving the target transport mechanism 72.

[0036]

[0039] The target transport mechanism 72 extends into the chamber 30, and the target material 26 is supplied from a target material reservoir 77. The target material reservoir 77 is in fluid communication with the target transport mechanism 72 via a reservoir target material outlet valve 78. The reservoir target material outlet valve 78 may be configured as a freeze valve, where the flow of molten tin is controlled by allowing molten tin to solidify within the valve, thereby closing the valve, and allowing solid tin to melt within the valve, thereby opening the valve. The target material reservoir 77 is also in fluid communication with a source of liquid target material via a reservoir target material inlet valve 79, which may also be configured as a freeze valve. In some embodiments, there is only a single target material conduit, which allows target material to be added to and removed from the target material reservoir 77, and which may function as both an inlet and an outlet.

[0037]

[0040] The liquid target material 26 in the target material reservoir 77 is maintained under pressure by gas supplied from a gas source (not shown) that is in fluid communication with the target material reservoir 77 through a reservoir gas inlet valve 71 .

[0038]

[0041] It will be appreciated that EUV radiation source 10 may include multiple target material reservoirs 77. The liquid target material 26 in target material reservoir 77 may be produced by any of several methods, which typically involve melting pure solid tin.

[0039]

[0042] Details regarding various droplet dispenser configurations are described, for example, in U.S. Pat. No. 7,872,245, issued Jan. 18, 2011, entitled "System and Method for Target Material Transport in a Laser-Produced Plasma EUV Light Source," U.S. Pat. No. 7,405,416, issued Jul. 29, 2008, entitled "Method and Apparatus for EUV Plasma Source Target Transport," and U.S. Pat. No. 7,372,056, issued May 13, 2008, entitled "LPPE UV Plasma Source Material Target Transport System."

[0040]

[0043] All patent applications, patents, and publications cited herein are incorporated by reference in their entirety, except for definitions, disclaimers, or disclaimers of subject matter, and except to the extent that the incorporated material contradicts an express disclosure herein. In the case of a conflict, the language of the disclosure herein will control.

[0041]

[0044] The configuration of FIG. 1 also includes one or more filters 80, 85 to block particles that may become entrained in the molten target material and otherwise clog the capillary 75. As shown, one filter 80 may be positioned within the target transport mechanism 72 immediately upstream of the capillary 75. Another filter 85 may be positioned, for example, between the target transport mechanism 72 and the target material reservoir 77. These filters may have porous filter elements formed, for example, from sintered tungsten. More information regarding filters is described, for example, in U.S. Patent No. 9,029,813, issued May 12, 2015, entitled "Filter for a Material Feed System of an Extreme Ultraviolet Light Source."

[0042]

[0045] The target material transport system 20 (including the target transport control system 70, the target transport mechanism 72, the capillary 75, and the filter 80), the target material reservoir 77, the filter 85, and the valves 71, 78, and 79 may be considered a target material storage and transport system 95. The target material storage and transport system 95 may also include a second reservoir, if used. The components of the target material storage and transport system 95 will typically be exposed to molten target material maintained at elevated pressure.

[0043]

[0046] EUV radiation source 10 also includes a target material receiver 87 that captures and holds target material that has not been altered by irradiation to limit contamination from such unaltered target material.

[0044]

[0047] Continuing with reference to FIG. 1 , EUV radiation source 10 may also include one or more optical elements. Collector 36 is shown as an example of such an optical element, although this description applies to other types of optical elements. Collector 36 may be a normal-incidence reflector implemented, for example, as a multilayer mirror with additional thin barrier layers, such as B4C, ZrC, Si3N4, or C, deposited at each layer interface to effectively block thermally induced interlayer diffusion. Collector 36 may take the form of an oblong ellipsoid with a central opening to allow beam 17 and conditioned beam 62 to pass through and reach illumination region 32. Collector 36 may have a first focus at illumination region 32 and a second focus at intermediate point 38 (also referred to as intermediate focus 38), where EUV radiation may be output from EUV radiation source 10 and input, for example, to an integrated circuit lithography scanner or stepper 90. An integrated circuit lithography scanner or stepper 90 uses this radiation to process a silicon wafer workpiece 92 in a known manner, for example, using a reticle or mask 94. The silicon wafer workpiece 92 is then further processed in a known manner to yield an integrated circuit device.

[0045]

[0048] FIG. 2 is a schematic diagram of the target material storage and delivery system 95 as shown in FIG. 1 . As can be seen, molten target material 26 is stored in the interior volume 76 of the target material reservoir 77 under pressure from gas introduced into the target material reservoir 77 via valve 71. The molten target material 26 flows through valve 78, along conduit 210, and through filter 85 to the interior volume 73 of the target transport mechanism 72. The molten target material 26 in the interior volume 73 of the target transport mechanism 72 passes through filter 80 and then through capillary 25 to generate droplets 25 in chamber 30. Those skilled in the art will appreciate that the filter 85 is not necessarily included in the configuration shown in FIG. 2 . In a system in which droplets move horizontally, causing the capillary 75 to be gravitationally directed downward, it will be understood that the molten target material 26 in the interior volume 76 of the target material reservoir 77 and the interior volume 73 of the target transport mechanism 72 will not necessarily fill those volumes partially as shown.

[0046]

[0049] 3 illustrates a possible configuration of a filter 80 according to one aspect of an embodiment. As shown, the filter 80 includes a generally cylindrical filter housing 100 defining a filter housing cavity 110. The filter housing 100 also defines a filter inlet 120 and a filter outlet 130. The filter inlet 120 and the filter outlet 140 are separated by a filter porous element 140 disposed within the filter housing cavity 110. The interior volume of the filter porous element 140 defines a filter porous element cavity 150.

[0047]

[0050] In use, molten target material enters filter 80 through filter inlet 120 and reaches filter porous element cavity 150. The molten target material must then pass through filter porous element 140 in order to flow through filter 80 to filter outlet 130.

[0048]

[0051] The filter porous element 140 may be made from a material such as sintered tungsten. The filter porous element 140 may be attached to the filter housing 100 by any suitable mechanical means, such as welding or joining with mechanical fasteners, to create an assembly.

[0049]

[0052] Several components of the target material containment and delivery system 95 are exposed to the pressurized molten target material. These components include the filter housing 100, which is conventionally made using molybdenum, such as molybdenum ASTM B387 Type 361 (Molybdenum 361). According to one aspect of the embodiment, one or more components of the target material containment and delivery system 95 exposed to the pressurized molten target material are made from an alloy of a refractory metal, such as a molybdenum-rhenium alloy, to enhance material strength. These components include various housings, such as pressure vessels, reservoirs, tubing, conduits, valves, and fittings, in addition to the filter housing. Refractory metals are a group of metallic elements that are highly resistant to heat and wear. Refractory metals include metals with melting points above 2000°C. Tungsten (W), molybdenum, niobium (Nb), tantalum (Ta), chromium (Cr), and rhenium (Re) are exemplary refractory metals. Hafnium (Hf), zirconium (Zr), and iridium (Ir) are also considered to be refractory metals, and the term "refractory metal" is used herein to describe all of these elements.

[0050]

[0053] One example of an alloy for making components such as the filter housing 100 is a molybdenum-rhenium (MoRe) alloy. When the target material is tin, MoRe is compatible with the melt target material. Mo-Re has substantially greater strength (substantially greater tensile strength) than unalloyed molybdenum materials such as Molybdenum 361. For example, Molybdenum 361 has a tensile strength of approximately 360 MPa at 300°C, while a MoRe alloy containing 52.5 wt% Mo and 47.5 wt% Re (Mo-47.5Re) has a tensile strength of approximately 630 MPa at 300°C.

[0051]

[0054] Therefore, the use of MoRe facilitates scaling up to operating with liquid tin at 1400 bar pressure. At the same time, the use of MoRe allows for the construction of components with more compact dimensions that fit within the dimensions allotted for existing target material containment and delivery systems. In other words, a cylindrical filter designed to withstand 1400 bar pressures made from Molybdenum-361 would need to have an outer diameter of more than 60 mm, while a filter designed to withstand 1400 bar pressures made from MoRe would only have an outer diameter of about 30 mm. Furthermore, the inclusion of rhenium in a molybdenum alloy improves the weldability and robustness of the final product. Alloying a material such as rhenium with molybdenum allows for the production of more robust products compared to those produced using unalloyed molybdenum. These advantages may be particularly evident in products whose manufacture involves welding.

[0052]

[0055] The relative proportions of Mo and Re in the alloy can vary. The composition described above, having 52.5 wt.% Mo and 47.5 wt.% Re (Mo-47.5Re), is readily available because it is manufactured as a standard alloy. A composition consisting of 55 wt.% Mo and 45 wt.% Re (Mo-45Re) is also readily available. Another possibility is a composition having 55.5 wt.% Mo and 44.5 wt.% Re (Mo-44.5Re). Typically, the rhenium content of Mo-Re alloys is preferably in the range of about 5 wt.% to about 50 wt.% Re, with the remainder being Mo in addition to normally present or unavoidable impurities. As used in this description and the appended claims, the term "about" means equal to the stated amount plus or minus a standard tolerance, e.g., + / - 5% of the stated amount.

[0053]

[0056] Refractory metals other than molybdenum, such as tantalum, can be alloyed with rhenium to produce TaRe. Similar to molybdenum, various relative proportions of these components can be used to produce alloys containing 97% by weight Ta and 3% by weight Re (Ta-3Re). Also, tungsten can be used as the primary component to produce alloys containing, for example, 75% by weight W and 25% by weight Re (W-25Re). Similar to molybdenum, the rhenium content of these alloys preferably ranges from about 5% by weight to about 50% by weight Re, with the remainder being tantalum or tungsten, respectively, in addition to unavoidable impurities.

[0054]

[0057] It is also possible to use an alloy of two refractory metals other than rhenium, such as tantalum-tungsten, or a molybdenum alloy containing a second refractory metal, such as hafnium and carbon, such as a molybdenum hafnium carbide alloy, which is a particle-reinforced molybdenum alloy containing hafnium and carbon (e.g., 0.8-1.4% hafnium, 0.05-0.15% carbon, the remainder hafnium).

[0055]

[0058] In some embodiments, the alloy is pure. Here and elsewhere herein, the term "pure" shall mean so-called "three nines" purity, i.e., 99.9% by weight purity. It will be understood that unavoidable impurities, as well as other materials, may be present at 0.010 weight percent or less. As used herein, the term "alloy" means a material composed of at least two metallic components purposefully combined to obtain a final material having one or more altered material properties.

[0056]

[0059] According to one aspect of the embodiment, at least some components of the target material containment and delivery system that are exposed to high pressure molten target material and are made from one of the alloys described above are manufactured so that the material properties of the alloy are substantially isotropic, for example, made using a powder metallurgy process, specifically a hot isostatic pressing (HIP) process that results in an alloy with isotropic properties. Here and elsewhere herein, the terms "isotropic" and "substantially isotropic" mean that the physical properties of the alloy are the same within + / - 5% regardless of the direction in which they are determined (axial, transverse, etc.).

[0057]

[0060] HIP is a materials manufacturing process in which starting powders or preformed shapes are simultaneously subjected to both high temperature and high isotropic pressure. The gas pressure is applied uniformly in all directions, hence the term isotropic. HIP can combine high temperatures (e.g., above 2200°C) and high isotropic gas pressures (e.g., in the range of 200-500 MPa). The HIP process can be used to produce isotropic alloys because it does not cause deformation due to the forming process.

[0058]

[0061] As an example of a target material storage and transport system component that can be advantageously fabricated from the alloys described above, FIG. 4 illustrates a nozzle assembly portion 200 of a target transport mechanism 72 according to certain aspects of the embodiment. A nozzle nut 210 attaches a ferrule 215 to a nozzle body 220. A nozzle cavity 235 corresponds to or is in fluid communication with the interior volume 73 of the target transport mechanism 72 and holds the liquid target material under pressure. The liquid target material flows down a capillary 75 and out a nozzle 225. A piezoelectric element 230 mechanically coupled to the capillary 75 introduces perturbations in the flow of liquid target material out of the nozzle 225 in a known manner. Also shown is a filter 80 positioned immediately upstream of the capillary 75 to prevent particulate contaminants in the nozzle cavity 235 from passing through to the capillary 75 and potentially clogging the nozzle 225.

[0059]

[0062] The present disclosure is presented using functional building blocks that illustrate the implementation of certain functions and their relationships. The boundaries of these functional building blocks are arbitrarily defined herein to facilitate clarity of description. Alternative boundaries may be defined so long as the certain functions are appropriately performed. For example, the functions of a control module may be divided into several systems or may be performed at least in part by an overall control system.

[0060]

[0063] The above description includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of elements or methodologies for purposes of describing the above-described embodiments, but one of ordinary skill in the art will recognize, after being given this disclosure, that many additional combinations and permutations of the various embodiments are possible. Accordingly, the described embodiments are intended to embrace all such modifications, improvements, and variations that fall within the spirit and scope of the appended claims. Furthermore, where used in the detailed description or claims, the term "including" is intended to be inclusive, similar to the interpretation of the terms "comprising" when employed as a transitional term in the claims. Furthermore, while elements of the described aspects and / or embodiments may be described or claimed in the singular, the plural is also intended unless the singular is expressly stated or otherwise clear from the context. Furthermore, all or a portion of any aspect and / or embodiment can be utilized with all or a portion of any other aspect and / or embodiment, unless expressly stated otherwise.

[0061]

[0064] The embodiments can be further described using the following clauses. 1. A target material storage and transport system adapted to transport target material to an irradiation site within an extreme ultraviolet radiation source, the target material storage and transport system including a filter positioned such that the target material passes through the filter as it passes through the target material storage and transport system, the filter including a filter housing, the filter housing including an alloy of a first refractory metal and a second refractory metal. 2. The target material containment and delivery system of clause 1, wherein the first refractory metal is ruthenium. 3. The target material containment and delivery system of clause 2, wherein the weight percentage of ruthenium in the alloy is in the range of 5% to about 50% by weight. 4. The target material containment and delivery system of clause 2, wherein the second refractory metal is molybdenum. 5. The target material containment and delivery system of clause 4, wherein the weight percentage of ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being molybdenum in addition to impurities normally present. 6. The target material containment and delivery system of clause 5, wherein the weight percentage of ruthenium in the alloy is about 47.5 weight percent, the remainder being molybdenum in addition to impurities normally present. 7. The target material containment and delivery system of clause 2, wherein the second refractory metal is tantalum. 8. The target material containment and delivery system of clause 7, wherein the weight percentage of ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being tantalum in addition to impurities normally present. 9. The target material containment and delivery system of clause 8, wherein the weight percentage of ruthenium in the alloy is about 47.5% by weight, the remainder being tantalum in addition to impurities normally present. 10. A molten tin containment and delivery system including at least one component in contact with pressurized molten tin, the at least one component comprising an alloy comprising a first high melting point metal and a second high melting point metal. 11. The molten tin containment and delivery system of clause 10, wherein the first high melting point metal is ruthenium. 12. The molten tin containment and delivery system of clause 11, wherein the weight percentage of ruthenium in the alloy is in the range of 5% to about 50% by weight. 13. The molten tin containment and delivery system of clause 11, wherein the second high melting point metal is molybdenum. 14. The molten tin containment and delivery system of clause 13, wherein the weight percent of ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being molybdenum in addition to impurities normally present. 15. The molten tin containment and delivery system of clause 14, wherein the weight percentage of ruthenium in the alloy is about 47.5% by weight, the remainder being molybdenum in addition to impurities normally present. 16. The molten tin containment and delivery system of clause 11, wherein the second high melting point metal is tantalum. 17. The molten tin containment and delivery system of clause 16, wherein the weight percentage of ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being tantalum in addition to impurities normally present. 18. The molten tin containment and delivery system of clause 17, wherein the weight percentage of ruthenium in the alloy is about 47.5% by weight, the remainder being tantalum in addition to impurities normally present. 19. A source of extreme ultraviolet radiation for semiconductor photolithography, comprising: a vacuum chamber; a collector optic disposed within the vacuum chamber and having a focal point within the chamber; a target material storage and delivery system arranged to distribute droplets of target material within the chamber at a focal point to an irradiation site, the target material storage and delivery system including a filter arranged such that the target material passes through the filter as it passes through the target material storage and delivery system, the filter including a filter housing, the filter housing including an alloy of a first refractory metal and a second refractory metal; a radiation source, 20. The radiation source of clause 19, wherein the first refractory metal is ruthenium. 21. The radiation source of clause 20, wherein the weight percentage of ruthenium in the alloy is in the range of 5% to about 50% by weight. 22. The radiation source of clause 21, wherein the second refractory metal is molybdenum. 23. The radiation source of clause 22, wherein the weight percentage of ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being molybdenum in addition to impurities normally present. 24. The radiation source of clause 23, wherein the weight percentage of ruthenium in the alloy is about 47.5% by weight, the remainder being molybdenum in addition to impurities normally present. 25. The radiation source of clause 20, wherein the second refractory metal is tantalum. 26. The radiation source of clause 25, wherein the weight percentage of ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being tantalum in addition to impurities normally present. 27. The radiation source of clause 26, wherein the weight percentage of ruthenium in the alloy is about 47.5% by weight, the remainder being tantalum in addition to impurities normally present. 28. A filter for a target material containment and transport system adapted to transport target material to an irradiation site within an extreme ultraviolet radiation source, the filter including a filter housing containing an alloy of a first refractory metal and a second refractory metal. 29. The filter of clause 28, wherein the first refractory metal is ruthenium. 30. The filter of clause 29, wherein the weight percent of ruthenium in the alloy is in the range of 5% to about 50% by weight. 31. The filter of claim 29, wherein the second high melting point metal is molybdenum. 32. The filter of clause 31, wherein the weight percent of ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being molybdenum in addition to impurities normally present. 33. A filter as described in clause 32, wherein the weight percentage of ruthenium in the alloy is about 47.5% by weight, the remainder being molybdenum in addition to impurities normally present. 34. The filter of claim 29, wherein the second high melting point metal is tantalum. 35. The filter of clause 34, wherein the weight percent of ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being tantalum in addition to impurities normally present. 36. A filter as described in clause 35, wherein the weight percentage of ruthenium in the alloy is about 47.5% by weight, the remainder being tantalum in addition to impurities normally present. 37. A source of extreme ultraviolet radiation for semiconductor photolithography, comprising: a vacuum chamber; a tin containment and delivery system arranged to dispense droplets of molten tin to an irradiation site within the chamber, the tin containment and delivery system including a filter arranged to remove particulate contaminants from the molten tin passing through the tin containment and delivery system, the filter including a filter housing containing an alloy of a first refractory metal and a second refractory metal; a radiation source,

[0062]

[0065] These and other implementations are within the scope of the following claims.

Claims

1. 1. A target material storage and transport system adapted to transport target material to an irradiation site within an extreme ultraviolet radiation source, the target material storage and transport system including a filter positioned such that target material passes through the filter as it passes through the target material storage and transport system, the filter including a filter housing, the filter housing including an alloy of a first refractory metal and a second refractory metal.

2. 10. The target material containment and transportation system of claim 1, wherein said first refractory metal is ruthenium.

3. The target material containment and transport system of claim 2 , wherein the weight percentage of the ruthenium in the alloy is in the range of 5% to about 50% by weight.

4. 3. The target material containment and transport system of claim 2, wherein the second refractory metal is molybdenum.

5. 5. The target material containment and transport system of claim 4, wherein the weight percentage of the ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being molybdenum in addition to impurities normally present.

6. 6. The target material containment and transport system of claim 5, wherein the weight percent of the ruthenium in the alloy is about 47.5% by weight, the remainder being molybdenum in addition to impurities normally present.

7. The target material containment and transport system of claim 2 , wherein the second refractory metal is tantalum.

8. 8. The target material containment and transport system of claim 7, wherein the weight percentage of the ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being tantalum in addition to impurities normally present.

9. 9. The target material containment and transport system of claim 8, wherein the weight percent of the ruthenium in the alloy is about 47.5% by weight, the remainder being tantalum in addition to impurities normally present.

10. 1. A molten tin containment and delivery system comprising at least one component in contact with pressurized molten tin, the at least one component comprising an alloy of a first high melting point metal and a second high melting point metal.

11. 11. The molten tin containment and delivery system of claim 10, wherein the first refractory metal is ruthenium.

12. 12. The molten tin containment and delivery system of claim 11, wherein the weight percentage of the ruthenium in the alloy is in the range of 5% to about 50% by weight.

13. 12. The molten tin containment and delivery system of claim 11, wherein the second refractory metal is molybdenum.

14. 14. The molten tin containment and delivery system of claim 13, wherein the weight percentage of the ruthenium in the alloy is in the range of 5% to about 50% by weight, with the remainder being molybdenum in addition to impurities normally present.

15. 15. The molten tin containment and delivery system of claim 14, wherein the weight percent of the ruthenium in the alloy is about 47.5% by weight, the remainder being molybdenum in addition to impurities normally present.

16. 12. The molten tin containment and transport system of claim 11, wherein the second refractory metal is tantalum.

17. 17. The molten tin containment and delivery system of claim 16, wherein the weight percentage of the ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being tantalum in addition to impurities normally present.

18. 18. The molten tin containment and delivery system of claim 17, wherein the weight percentage of the ruthenium in the alloy is about 47.5% by weight, the remainder being tantalum in addition to impurities normally present.

19. 1. A source of extreme ultraviolet radiation for semiconductor photolithography, comprising: a vacuum chamber; a collector optic disposed within the vacuum chamber and having a focal point within the chamber; a target material storage and delivery system arranged to distribute droplets of target material within the chamber at the focal point to an irradiation site, the target material storage and delivery system including a filter arranged such that target material passes through the filter as it passes through the target material storage and delivery system, the filter including a filter housing, the filter housing including an alloy of a first refractory metal and a second refractory metal; a radiation source,

20. 20. The radiation source of claim 19, wherein the first refractory metal is ruthenium.

21. The radiation source of claim 20, wherein a weight percentage of the ruthenium in the alloy is in the range of 5% to about 50% by weight.

22. 22. The radiation source of claim 21 , wherein the second refractory metal is molybdenum.

23. 23. The radiation source of claim 22, wherein the weight percentage of the ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being molybdenum in addition to impurities normally present.

24. 24. The radiation source of claim 23, wherein the weight percentage of the ruthenium in the alloy is about 47.5% by weight, the remainder being molybdenum in addition to impurities normally present.

25. 21. The radiation source of claim 20, wherein the second refractory metal is tantalum.

26. 26. The radiation source of claim 25, wherein the weight percentage of the ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being tantalum in addition to impurities normally present.

27. 27. The radiation source of claim 26, wherein the weight percentage of the ruthenium in the alloy is about 47.5% by weight, the remainder being tantalum in addition to impurities normally present.

28. 1. A filter for a target material containment and transport system adapted to transport target material to an irradiation site within an extreme ultraviolet radiation source, the filter comprising a filter housing containing an alloy of a first refractory metal and a second refractory metal.

29. 29. The filter of claim 28, wherein the first refractory metal is ruthenium.

30. 30. The filter of claim 29, wherein the weight percent of the ruthenium in the alloy is in the range of 5% to about 50% by weight.

31. 30. The filter of claim 29, wherein the second refractory metal is molybdenum.

32. 32. The filter of claim 31, wherein the weight percentage of the ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being molybdenum in addition to impurities normally present.

33. 33. The filter of claim 32, wherein the weight percent of the ruthenium in the alloy is about 47.5% by weight, the remainder being molybdenum in addition to impurities normally present.

34. 30. The filter of claim 29, wherein the second refractory metal is tantalum.

35. 35. The filter of claim 34, wherein the weight percentage of the ruthenium in the alloy is in the range of 5% to about 50% by weight, the remainder being tantalum in addition to impurities normally present.

36. 36. The filter of claim 35, wherein the weight percent of the ruthenium in the alloy is about 47.5% by weight, the remainder being tantalum in addition to impurities normally present.

37. 1. A source of extreme ultraviolet radiation for semiconductor photolithography, comprising: a vacuum chamber; a tin containment and delivery system arranged to distribute droplets of molten tin to irradiation sites within the chamber, the tin containment and delivery system including a filter arranged to remove particulate contaminants from the molten tin passing through the tin containment and delivery system, the filter including a filter housing containing an alloy of a first refractory metal and a second refractory metal; a radiation source,

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