Modular gas purification system for radiation source

Abstract

A radiation source includes a chamber and a gas purification apparatus. The chamber includes an irradiation region. The gas purification apparatus includes a gas pathway structure to direct an unpurified gas having contaminants. The gas pathway structure includes a first pathway section and a second pathway section. The first pathway section includes contaminant capture elements to capture the contaminant to produce purified gas. At least a portion of the contaminant capture elements are disposed along a plane that is substantially normal to a drift direction of the unpurified gas at the plane. The second pathway section includes gas cooling elements disposed downstream of the contaminant capture elements. The gas cooling elements cool the purified gas. An orientation of the second pathway structure is such that a drift direction of the purified gas is different from the drift direction of the unpurified gas.

Description

MODULAR GAS PURIFICATION SYSTEM FOR RADIATION SOURCECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Application No. 63 / 621,923, filed lanuary 17, 2024, titled MODULAR GAS PURIFICATION SYSTEM FOR RADIATION SOURCE, which is incorporated herein by reference in its entirety.FIELD

[0002] The present application relates to extreme ultraviolet (“EUV”) radiation sources and methods thereof. EUV radiation can be used as, for example, exposure radiation in a lithographic process to fabricate semiconductor devices.BACKGROUND

[0003] A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that instance, a patterning device, which can be a mask or a reticle, can be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g., comprising part of, one, or several dies) on a substrate (e.g., a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (photoresist or simply “resist”) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Known lithographic apparatuses include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning”-direction) while synchronously scanning the target portions parallel or anti-parallel to this scanning direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0004] A lithographic apparatus typically includes an illumination system that conditions radiation generated by a radiation source before the radiation is incident upon a patterning device. A patterned beam of EUV light can be used to produce extremely small features on a substrate. EUV light (also sometimes referred to as soft x-rays) is generally defined as electromagnetic radiation having wavelengths in the range of about 5-100 nm. One particular wavelength of interest for photolithography occurs at 13.5 nm.

[0005] Methods to produce EUV light include, but are not necessarily limited to, converting a source material into a plasma state that has a chemical element with an emission line in the EUV range. These elements can include, but are not necessarily limited to, xenon, lithium and tin.

[0006] In one such method, often termed laser-produced plasma (“LPP”), the desired plasma can be produced by irradiating a source material, for example, in the form of a droplet, stream or wire, with a laser beam. In another method, often termed discharge produced plasma (“DPP”), the plasma can be generated by positioning source material having an appropriate emission line between a pair of electrodes and causing an electrical discharge to occur between the electrodes.

[0007] In an example involving tin droplets to generate LPP, the spent tin material is then guided to an exhaust. In the process of evacuating the spent tin, some of the material may accumulate on surfaces, causing contamination and eventual malfunction of the EUV light source.SUMMARY

[0008] Accordingly, it is desirable to improve contaminant-scrubbing processes in EUV sources to increase longevity of EUV sources, reduce maintenance downtime, and increase throughput in EUV lithographic apparatuses.

[0009] In some aspects, a lithographic apparatus comprises an illumination system and a gas purification apparatus. The illumination system is configured to illuminate a pattern of a patterning device and to produce an unpurified gas comprising a contaminant. The gas purification apparatus comprises a gas pathway structure configured to direct the unpurified gas. The gas pathway structure comprises a first pathway section and a second pathway section. The first pathway section comprises contaminant capture elements configured to capture the contaminant to produce purified gas. At least a portion of the contaminant capture elements are disposed along a plane that is substantially normal to a drift direction of the unpunfied gas at the plane. The second pathway section comprises gas cooling elements disposed downstream of the contaminant capture elements. The gas cooling elements are configured to cool the purified gas. An orientation of the second pathway structure is such that a drift direction of the purified gas is different from the drift direction of the unpurified gas.

[0010] In some aspects, a gas purification apparatus comprises a gas pathway structure configured to direct an unpurified gas comprising an impurity. The gas pathway structure comprises a first pathway section and a second pathway section. The first pathway section comprises impurity capture elements configured to capture the impurity to produce purified gas. At least a portion of the impurity capture elements are disposed along one or more planes, wherein a plane of the one or more planes is substantially normal or parallel to a drift direction of the unpurified gas at the plane. The second pathway section comprises gas cooling elements disposed downstream of the impurity capture elements. The gas cooling elements are configured to cool the purified gas. An orientation of the second pathway section is such that a drift direction of the purified gas is different from the drift direction of the unpurified gas.

[0011] In some aspects, a method for operating a fluid purification apparatus efficiently directs a fluid through a compact volume. The method comprises directing an unpurified fluid via a fluid pathway structure of a fluid purification apparatus. The unpurified fluid comprises a contaminant. Thedirecting comprises flowing the unpurified fluid through a first pathway section of the fluid pathway structure such that a drift direction of the unpurified fluid is substantially normal to a plane defined by an array of contaminant capture elements. The method also comprises producing purified fluid from the unpurified fluid. The producing comprises capturing the contaminant using the contaminant capture elements. The method also comprises cooling the purified fluid using cooling elements disposed at a second pathway section of the fluid pathway structure and downstream of the contaminant capture elements. The method also comprises directing the purified fluid such that a drift direction of the purified fluid at the cooling elements is different from the drift direction of the unpurified fluid at the plane.

[0012] Further features of various aspects of the present disclosure are described in detail below with reference to the accompanying drawings. It is noted that the present disclosure is not limited to the specific aspects described herein. Such aspects are presented herein for illustrative purposes only. Additional aspects will be apparent to those skilled in the relevant art(s) based on the teachings contained herein.BRIEF DESCRIPTION OF THE DRAWINGS / FIGURES

[0013] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable those skilled in the relevant art(s) to make and use aspects described herein.

[0014] FIG. 1 shows a reflective lithographic apparatus, according to some aspects.

[0015] FIGS. 2A, 2B, and 3 show more details of a reflective lithographic apparatus, according to some aspects.

[0016] FIG. 4 shows a lithographic cell, according to some aspects.

[0017] FIG. 5 shows a gas purification apparatus, according to some aspects.

[0018] FIG. 6 shows a gas purification apparatus, according to some aspects.

[0019] FIG. 7 shows a flowchart of a method for efficiently directing a fluid through a fluid purification apparatus, according to some aspects.

[0020] FIG. 8 shows a gas purification apparatus, according to some aspects.

[0021] The features of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and / or structurally similar elements. Additionally, generally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears. Unless otherwise indicated, the drawings provided throughout the disclosure should not be interpreted as to-scale drawings.DETAILED DESCRIPTION

[0022] The aspects described herein, and references in the specification to “one aspect,” “an aspect,” “an exemplary aspect,” “an example aspect,” etc., indicate that the aspects described can include a particular feature, structure, or characteristic, but every aspect may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same aspect. Further, when a particular feature, structure, or characteristic is described in connection with an aspect, it is understood that it is within the knowledge of those skilled in the art to effect such feature, structure, or characteristic in connection with other aspects whether or not explicitly described.

[0023] Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “on,” “upper” and the like, can be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein can likewise be interpreted accordingly.

[0024] The terms “about,” “approximately,” or the like can be used herein indicates the value of a given quantity that can vary based on a particular technology. Based on the particular technology, the terms “about,” “approximately,” or the like can indicate a value of a given quantity that varies within, for example, 10-30% of the value (e.g., ±10%, ±20%, or ±30% of the value).

[0025] Aspects of the present disclosure can be implemented in hardware, firmware, software, or any combination thereof. Aspects of the disclosure can also be implemented as instructions stored on a computer-readable medium, which can be read and executed by one or more processors. A machine- readable medium can include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium can comprise read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustical or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc ), and others. Furthermore, firmware, software, routines, and / or instructions can be described herein as performing certain actions. However, it should be appreciated that such descriptions are merely for convenience and that such actions result from computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc. The term “machine -readable medium” can be interchangeable with similar terms, for example, “computer program product,” “computer-readable medium,” “non-transitory computer-readable medium,” or the like. The term “non -transitory” can be used herein to characterize one or more forms of computer readable media except for a transitory, propagating signal.

[0026] Before describing such aspects in more detail, however, it is instructive to present an example environment in which aspects of the present disclosure can be implemented.

[0027] Example Lithographic Systems

[0028] FIG. 1 shows a lithographic apparatus 100 in which aspects of the present disclosure can be implemented. In some aspects, lithographic apparatus 100 can comprise the following: an illumination system (illuminator) IL configured to condition a radiation beam B (for example, deep ultra violet or extreme ultra violet radiation); a support structure (for example, a mask table) MT configured to support a patterning device (for example, a mask, a reticle, or a dynamic patterning device) MA and connected to a first positioner PM configured to accurately position patterning device MA; and, a substrate table (for example, a wafer table) WT configured to hold a substrate (for example, a resist coated wafer) W and connected to a second positioner PW configured to accurately position substrate W. Lithographic apparatus 100 also comprises a projection system PS configured to project a pattern imparted to radiation beam B by patterning device MA onto a target portion (for example, comprising one or more dies) C of substrate W. In lithographic apparatus 100, patterning device MA and the projection system PS are reflective.

[0029] Illumination system IL can comprise various types of optical components, such as refractive, reflective, catadioptric, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, for directing, shaping, or controlling the radiation beam B . Illumination system IL can also comprise a sensor ES that provides a measurement of, for example, one or more of energy per pulse, photon energy, intensity, average power, and the like. Illumination system IL can comprise a measurement sensor MS for measuring a movement of radiation beam B and a uniformity compensator UC that allow an illumination slit uniformity to be controlled. Measurement sensor MS can also be disposed at other locations. For example, measurement sensor MS can be on or near substrate table WT.

[0030] In some aspects, support structure MT can support patterning device MA in a manner that depends on the orientation of the patterning device MA with respect to a reference frame, the design of lithographic apparatus 100, and other conditions, such as whether or not the patterning device MA is held in a vacuum environment. Support structure MT can implement mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device MA. Support structure MT can be a frame or a table. Support structure MT can be fixed or movable. By using sensors, support structure MT can ensure that patterning device MA is at a desired position (e.g., a given position with respect to the projection system PS).

[0031] The term “patterning device” can be used herein to refer to any device that can be used to impart a radiation beam B with a pattern in its cross-section, such as to create a pattern in target portion C of substrate W. The pattern imparted to radiation beam B can correspond to a particular functional layer in a device being created in target portion C to form an integrated circuit.

[0032] Patterning device MA can be reflective. Examples of patterning devices MA include reticles, masks, programmable mirror arrays, or programmable LCD panels. Masks can include different masktypes, such as binary, alternating phase shift, or attenuated phase shift, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions. The tilted mirrors can impart a pattern in radiation beam B, which is reflected by a matrix of small mirrors.

[0033] In some aspects, the term “projection system” can be used herein to refer to any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, or for other factors, such as the use of an immersion liquid on the substrate W or the use of a vacuum. Atmospheric gas can absorb EUV or electrons used for exposing a substrate. Therefore, a vacuum environment can be used for EUV or electron beam radiation. A vacuum environment can be provided to the whole beam path with the aid of a vacuum wall and vacuum pumps.

[0034] Lithographic apparatus 100 can be of a type having two (dual stage) or more substrate tables WT (and / or two or more mask tables). In such “multiple stage” machines, additional substrate tables WT can be used in parallel, or preparatory steps can be carried out on one or more tables while one or more other substrate tables WT are being used for exposure. In some situations, the additional table may be different from substrate table WT.

[0035] In some aspects, lithographic apparatus 100 can be of a type in which at least a portion of the substrate can be covered by a liquid having a relatively high refractive index, e.g., water, so as to fill a space between the projection system and the substrate. An immersion liquid can also be applied to other spaces in the lithographic apparatus, for example, between the mask and the projection system. Immersion techniques can increase the numerical aperture of projection systems. The term “immersion” as used herein does not mean that a structure, such as a substrate, must be submerged in liquid. For example, a liquid can be located between the projection system and the substrate during exposure.

[0036] Illuminator IL can receive a radiation beam from a radiation source SO. Source SO and lithographic apparatus 100 can be separate physical entities. In such cases, source SO is not considered to be part of lithographic apparatus 100 and radiation beam B can pass from source SO to illuminator IL with the aid of a beam delivery system (not shown), which can include, for example, suitable directing mirrors and / or a beam expander. In other cases, source SO can be an integral part of the lithographic apparatus 100. A radiation system can comprise source SO, illuminator IL, and / or beam delivery system BD.

[0037] In some aspects, illuminator IL can be used to condition radiation beam B to have a desired uniformity and intensity distribution in its cross section. The desired uniformity of radiation beam B can be maintained by using uniformity compensator UC. Uniformity compensator UC can comprise a plurality of protrusions (e.g., fingers) that can be adjusted in the path of radiation beam B to controlthe uniformity of radiation beam B. Measurement sensor MS can be used to monitor the uniformity of radiation beam B.

[0038] Radiation beam B can be incident on patterning device MA, which is held on the support structure MT, and in this manner, radiation beam B can be patterned by the patterning device MA. In lithographic apparatus 100, radiation beam B can be reflected from the patterning device (for example, mask) MA. After being reflected from the patterning device MA, radiation beam B can pass through projection system PS, which focuses the radiation beam B onto a target portion C of the substrate W. With the aid of the second positioner PW and position sensor IF2 (for example, an interferometric device, linear encoder, or capacitive sensor), substrate table WT can be moved accurately (for example, so as to position different target portions C in the path of the radiation beam B). Similarly, first positioner PM and another position sensor IF1 can be used to accurately position the patterning device (for example, mask) MA with respect to the path of the radiation beam B. Patterning device MA and substrate W can be aligned using mask alignment marks Ml, M2 and substrate alignment marks Pl, P2.

[0039] In some aspects, lithographic apparatus 100 can be used in at least one of the following modes:

[0040] 1 In step mode, support structure MT and substrate table WT can be kept essentially stationary, while an entire pattern imparted to radiation beam B is projected onto a target portion C at one time (e.g., a single static exposure). Substrate table WT can then be shifted in the X and / or Y direction so that a different target portion C can be exposed.

[0041] 2 In scan mode, support structure MT and substrate table WT can be scanned synchronously while a pattern imparted to radiation beam B is projected onto a target portion C (e.g., a single dynamic exposure). The velocity and direction of substrate table WT relative to support structure MT can be determined by (de-)magnification and image reversal characteristics of projection system PS.

[0042] 3 In another mode, support structure MT can be kept substantially stationary holding a programmable patterning device, and substrate table WT can be moved or scanned while a pattern imparted to radiation beam B is projected onto a target portion C. A pulsed radiation source SO can be employed and the programmable patterning device is updated after each movement of substrate table WT or in between successive radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography that utilizes a programmable patterning device, such as a programmable mirror array.

[0043] Combinations and / or variations on the described modes of use or entirely different modes of use can also be employed.

[0044] In some aspects, lithographic apparatus 100 can comprise an EUV radiation source configured to generate a beam of EUV radiation for EUV lithography. The EUV radiation source canbe configured in a radiation system, and a corresponding illumination system is configured to condition the EUV radiation beam of the EUV source.

[0045] FIG. 2A shows different view of lithographic apparatus 100, including source SO (e.g., source collector apparatus), illumination system IL, and projection system PS, according to some aspects. Source SO is constructed and arranged such that a vacuum environment can be maintained in an enclosing structure 220 of source SO. An EUV radiation emitting plasma 210 can be formed by a discharge-generated plasma source. In some aspects, a plasma of excited tin (Sn) (e g., excited via a laser) is used to produce EUV radiation.

[0046] The radiation emitted by the EUV radiation emitting plasma 210 can be passed from a source chamber 211 into a collector chamber 212 via an optional gas barrier or contaminant trap 230 (in some cases also referred to as contaminant barrier or foil trap), which is positioned in or behind an opening in source chamber 211. Contaminant trap 230 can comprise a channel structure. Contamination trap 230 can also comprise a gas barrier and / or a channel structure.

[0047] In some aspects, collector chamber 212 can comprise a radiation collector CO. Radiation collector CO can be a so-called grazing incidence collector. Radiation collector CO can comprise an upstream radiation collector side 251 and a downstream radiation collector side 252. Radiation that traverses radiation collector CO can be reflected off a grating spectral filter 240 to be focused in a virtual source point INTF. Virtual source point INTF can be referred to as the intermediate focus. Source collector apparatus can be arranged such that the intermediate focus INTF is located at or near an opening 219 of enclosing structure 220. The virtual source point INTF can be an image of the EUV radiation emitting plasma 210. Grating spectral filter 240 can be used for suppressing infrared (IR) radiation.

[0048] Subsequently, the radiation traverses the illumination system IL. Illumination system IL can include a faceted field mirror device 222 and a faceted pupil mirror device 224 arranged to provide a desired angular distribution of radiation beam 221, at patterning device MA, as well as a desired uniformity of radiation intensity at patterning device MA. Upon reflection of beam of radiation 221 at patterning device MA, held by support structure MT, a patterned beam 226 is formed and the patterned beam 226 is imaged by projection system PS via reflective elements 228, 229 onto substrate W held by the wafer stage or substrate table WT. In some aspects, other configurations of mirrors and / or optical devices can be used to direct radiation beam 221 to patterning device MA.

[0049] More elements than shown can generally be present in illumination system IL and projection system PS. Grating spectral filter 240 can optionally be present, depending upon the type of lithographic apparatus. Further, there can be more mirrors present than those shown in the FIG. 2A, for example there can be one to six additional reflective elements present in the projection system PS than shown in FIG. 2A.

[0050] In some aspects, uniformity compensator UC, sensor ES, and / or measurement sensor MS shown in FIGS. 2A and 2B can be as described above in reference to FIG. 1.

[0051] Collector CO, as illustrated in FIG. 2A, is depicted as an example of a nested collector with grazing incidence reflectors 253, 254, and 255 (or collector mirror). Grazing incidence reflectors 253, 254, and 255 can be disposed axially symmetric around an optical axis O. A collector optic of this type can be used in combination with a discharge-generated plasma source, often called a DPP source.

[0052] FIG. 2B shows a portion of lithographic apparatus 100 (e.g., FIG. 1), but with alternative collection optics in source SO, according to some aspects. It should be appreciated that structures shown in FIG. 2A that do not appear in FIG. 2B (for drawing clarity) can still be included in aspects referring to FIG. 2B. Elements in FIG. 2B having the same reference numbers as those in FIG. 2A have the same or substantially similar structures and functions as described in reference to FIG. 2A. In some aspects, the lithographic apparatus 100 can be used, for example, to expose a substrate W such as a resist-coated wafer with a patterned beam of EUV illumination. In FIG. 2B, illumination system IL and projection system PS are represented combined as an exposure device 256 (e.g., an integrated circuit lithography tool such as a stepper, scanner, step and scan system, direct write system, device using a contact and / or proximity mask, etc.) that uses EUV light from source SO. Lithographic apparatus 100 can also comprise collector 258 that reflects EUV light from the EUV radiation emitting plasma 210 along a path into the exposure device 256 to irradiate substrate W. Collector 258 can comprise a near-normal incidence collector mirror having a reflective surface in the form of a prolate spheroid (e.g., an ellipse rotated about its major axis). The prolate spheroid structure can have a graded multi-layer coating with alternating layers of Molybdenum and Silicon, and in some cases, one or more high temperature diffusion barrier layers, smoothing layers, capping layers and / or etch stop layers.

[0053] FIG. 3 shows a detailed view of a portion of lithographic apparatus 100 (e.g., FIGS. 1, 2A, and 2B), according to one or more aspects. Elements in FIG. 3 having the same reference numbers as those in FIGS. 1, 2A, and 2B have the same or substantially similar structures and functions as described in reference to FIGS. 1, 2A, and 2B. In some aspects, source SO can be a LPP EUV source. Source SO can comprise a laser system 302 for generating a train of light pulses and delivering the light pulses into a light source chamber 212. For the lithographic apparatus 100, the light pulses can travel along one or more beam paths from the laser system 302 and into the chamber 212 to illuminate a source material at an irradiation region 304 to generate a plasma (e.g., plasma region located at EUV radiation emitting plasma 210 in FIG. 2B) that produces EUV light for substrate exposure in the exposure device 256.

[0054] In some aspects, laser system 302 can comprise a pulsed laser device, e.g., a pulsed gas discharge CO2 laser device producing radiation at 9.3 pm or 10.6 pm, e.g., with DC or RF excitation, operating at relatively high power, e g., 10 kW or higher and high pulse repetition rate, e.g., 50 kHz or more. In some aspects, the laser can be an axial -flow RF -pumped CO2 laser having an oscillator amplifier configuration (e.g., master oscillator / power amplifier (MOPA) or power oscillator / power amplifier (POPA)) with multiple stages of amplification and having a seed pulse that is initiated by aQ-switched oscillator with relatively low energy and high repetition rate, e.g., capable of 100 kHz operation. From the oscillator, the laser pulse can then be amplified, shaped and / or focused before reaching the irradiation region 304. Continuously pumped CO2 amplifiers can be used for the laser system 302. Alternatively, the laser can be configured as a so-called “self-targeting” laser system in which the droplet serves as one mirror of the optical cavity of the laser.

[0055] In some aspects, depending on the application, other types of lasers can also be suitable, e.g., an excimer or molecular fluorine laser operating at high power and high pulse repetition rate. Some examples include, a solid state laser, e.g., having a fiber, rod, slab, or disk-shaped active media, other laser architectures having one or more chambers, e.g., an oscillator chamber and one or more amplifying chambers (with the amplifying chambers in parallel or in series), a master oscillator / power oscillator (MOPO) arrangement, a master oscillator / power ring amplifier (MOPRA) arrangement, or a solid state laser that seeds one or more excimer, molecular fluorine or CO2 amplifier or oscillator chambers, can be suitable. Other suitable designs are envisaged.

[0056] In some aspects, a source material can first be irradiated by a pre-pulse and thereafter irradiated by a main pulse. Pre-pulse and main pulse seeds can be generated by a single oscillator or two separate oscillators. One or more common amplifiers can be used to amplify both the pre-pulse seed and main pulse seed. In some aspects, separate amplifiers can be used to amplify the pre-pulse and main pulse seeds.

[0057] In some aspects, source SO can also comprise a beam conditioning unit 306 having one or more optics for beam conditioning, such as expanding, steering, and / or focusing the beam between the laser system 302 and irradiation region 304. For example, a steering system, which can comprise one or more mirrors, prisms, lenses, etc., can be provided and arranged to steer the laser focal spot to different locations in the chamber 212. For example, the steering system can comprise a first flat mirror mounted on a tip-tilt actuator, which can move the first mirror independently in two dimensions, and a second flat mirror mounted on a tip-tilt actuator which can move the second mirror independently in two dimensions. With the described arrangement(s), the steering system can controllably move the focal spot in directions substantially orthogonal to the direction of beam propagation (beam axis or optical axis).

[0058] Beam conditioning unit 306 can comprise a focusing assembly to focus the beam to irradiation region 304 and adjust the position of the focal spot along the beam axis. For the focusing assembly, an optic, such as a focusing lens or mirror, can be used that is coupled to an actuator for movement in a direction along the beam axis to move the focal spot along the beam axis.

[0059] In some aspects, the source SO can also comprise a source material delivery system 308 for delivering source material, such as tin droplets, to irradiation region 304, where the droplets can interact with light pulses from the laser system 302 to produce plasma and generate an EUV emission. The EUV emission is used to expose a substrate such as a resist-coated wafer at exposure device 256. More details regarding various droplet dispenser configurations can be found in, e g., U.S. Pat. No.7,872,245, issued on January 18, 2011, titled “Systems and Methods for Target Material Delivery in a Laser Produced Plasma EUV Light Source”, U.S. Pat. No. 7,405,416, issued on July 29, 2008, titled “Method and Apparatus For EUV Plasma Source Target Delivery”, U.S. Pat. No. 7,372,056, issued on May 13, 2008, titled “LPP EUV Plasma Source Material Target Delivery System”, and International Appl. No. WO 2019 / 137846, titled “Apparatus for and Method of Controlling Coalescence of Droplets In a Droplet Stream”, published on July 18, 2019, the contents of each of which are incorporated by reference herein in their entirety.

[0060] In some aspects, the source material for producing an EUV light output for substrate exposure can include, but is not necessarily limited to, a material that includes tin, lithium, xenon or combinations thereof. The source material can be in the form of liquid droplets and / or solid particles contained within liquid droplets. For example, the element tin can be used as pure tin, as a tin compound, e.g., SnBn, SnBn, SnFL, as a tin alloy, e.g., tin-gallium alloys, tin-indium alloys, tin- indium-gallium alloys, or a combination thereof. Depending on the material used, the source material, when sent to irradiation region 304, can be at various temperatures, for example, room temperature or near room temperature (e g., tin alloys, SnBn). at an elevated temperature (e.g., pure tin), or at temperatures below room temperature (e.g., SnFL).

[0061] In some aspects, the source SO can also comprise a controller 310 and / or a drive laser control system 312 for controlling devices in laser system 302 to generate light pulses for delivery into the chamber 212 and / or for controlling movement of optics in beam conditioning unit 306. Source SO can also comprise a droplet position detection system which can comprise one or more droplet imagers 314 that provide an output signal indicative of the position of one or more droplets (e.g., to ensure that droplets arrive on target at irradiation region 304). The droplet imager(s) 314 can provide measurement output to a droplet position detection feedback system 316. Droplet position detection feedback system 316 can compute a droplet position and trajectory, from which a droplet error can be computed (e.g., on a droplet-by-droplet basis, or on average). The droplet error can then be provided as an input to controller 310, which can, for example, provide a position, direction and / or timing correction signal to laser system 302 to control laser trigger timing and / or to control movement of optics in beam conditioning unit 306, e.g., to change the location and / or focal power of the light pulses being delivered to irradiation region 304 in chamber 212. Furthermore, source material delivery system 308 can comprise a control system operable in response to a signal from controller 310 (which in some implementations can include the droplet error described above, or some quantity derived therefrom) to modify the release point, initial droplet stream direction, droplet release timing and / or droplet modulation to correct for errors in the droplets arriving at irradiation region 304.

[0062] In some aspects, the lithographic apparatus 100 can also comprise a collector 258 and a gas dispenser device 320. Gas dispenser device 320 can dispense gas in the path of the source material from source material delivery system 308 (e.g., irradiation region 304). Gas dispenser device 320 can comprise a nozzle through which dispensed gas can exit. Gas dispenser device 320 can be structured(e.g., having an aperture) such that, when placed near the optical path of laser system 302, light from laser system 302 is not blocked by gas dispenser device 320 and is allowed to reach irradiation region 304. A buffer gas such as hydrogen, helium, argon or combinations thereof, can be introduced into chamber 212. The buffer gas can be present in the chamber 212 during plasma discharge and can act to slow plasma-created ions, reduce degradation of optics, and / or increase plasma efficiency. Alternatively, a magnetic field and / or electric field (not shown) can be used alone, or in combination with a buffer gas, to reduce damage caused by fast-moving ions.

[0063] In some aspects, collector 258 can be a near-normal incidence collector mirror having a reflective surface in the form of a prolate spheroid as described above. Collector 258 can be formed with an aperture to allow the light pulses generated by laser system 302 to pass through and reach irradiation region 304. The same, or another aperture, can be used to allow gas from the gas dispenser device 320 to flow into chamber 212. As shown, the collector 258 can be, e.g., a prolate spheroid mirror that has a first focus within or near the irradiation region 304 and a second focus at an intermediate region 318, where the EUV light can be transmitted to exposure device 256. It is to be appreciated that other optics can be used in place of the prolate spheroid mirror for collecting and directing light to an intermediate location for subsequent delivery to a device utilizing EUV light. It is also envisaged that structures and functions described in reference to FIG. 3 can be used with collectors other than collector 258 (e g., collector CO (FIG. 2A)).

[0064] Example Lithographic Cell

[0065] FIG. 4 shows a lithographic cell 400, also sometimes referred to a lithocell or cluster, according to some aspects. Lithographic apparatus 100 (FIGS. 1, 2A, 2B, and 3) can form part of lithographic cell 400. Lithographic cell 400 can also comprise one or more apparatuses to perform pre-exposure and post-exposure processes on a substrate. These can include spin coaters SC to deposit resist layers, developers DE to develop exposed resist, chill plates CH, and bake plates BK. A substrate handler, or robot, RO picks up substrates from input / output ports I / Ol, I / O2, moves them between the different process apparatuses and delivers them to the loading bay LB of the lithographic apparatus 100. These devices, which are often collectively referred to as the track, are under the control of a track control unit TCU, which is itself controlled by a supervisory control system SCS, which also controls the lithographic apparatus via lithography control unit LACU. Thus, the different apparatuses can be operated to maximize throughput and processing efficiency.

[0066] Example Gas Purification System

[0067] Referring to FIG. 3, one or more components of source SO can be sensitive to contamination caused by the droplet material. It was described above that a buffer gas such as hydrogen, helium, argon or combinations thereof, can be introduced into chamber 212 to increase the efficiency of the plasma-generating process. The buffer gas can be used to carry away spent droplet material fordisposal. A buffer gas flow 305 is illustrated in FIG. 3. Source SO can comprise a gas purification apparatus 307. An exhaust system 309 can be connected to gas purification apparatus 307. Collector 258 can be adversely impacted if droplet material is allowed to accumulate on collector 258. Hence, buffer gas flow 305 can push the spent droplet material away from irradiation region 304 and away from collector 258. A direction of buffer gas flow 305 can be controlled by pressure differentials

[0068] Collector is not the only component that is sensitive to contamination. For example, exhaust system 309 can accumulate droplet material over time and thus malfunction. A goal of exhaust system 309 is to provide outflow for the buffer gas. Filters and other sensitive components of exhaust system 309 can become clogged by the contamination, which can degrade performance of source SO. Consequently, accumulation of contaminant can trigger costly and laborious maintenance processes to restore proper function of source SO.

[0069] It is desirable to prevent unscheduled or unforeseen maintenance of source SO. It is also desirable to reduce the frequency of scheduled maintenance of source SO such that lithographic apparatus 100 (FIGS. 1-4) can be operated for longer periods of time with fewer interruptions. As a result, throughput of lithographic apparatus 100 (FIGS. 1-4) can be improved. In some aspects, the term “throughput” can be used herein to refer to a speed at which an amount of material or items pass through a system or process. The term “throughput” can characterize a speed of overall lithographic fabrication, a rate at which a wafer passes through a lithographic apparatus, a rate at which a wafer clears a particular fabrication step and moves on to the next step, or the like. Hence, “throughput” can be a performance marker of a lithographic apparatus. It is desirable for lithographic systems to output as many products as possible in as little time as possible. Increasing the time period in between maintenance actions can increase throughput.

[0070] In some aspects, gas purification apparatus 307 performs scrubbing functions to filter out contaminant from the buffer gas stream. In this manner, exhaust system 309 can operate for longer periods of time.

[0071] FIG. 5 shows a cross section of a gas purification apparatus 500, according to some aspects. In some aspects, gas purification apparatus 500 can be implemented in a source SO of a lithographic apparatus.

[0072] In some aspects, gas purification apparatus 500 comprises a gas pathway structure 502, conduit 508, and contaminant capture elements 504. Gas pathway structure 502 comprises a pathway section 506. Gas pathway structure 502 can direct a flow of unpurified gas 510. Unpurified gas 510 can comprise a contaminant or impurity. A contaminant or impurity can be a plurality of particles of one or more types of material. Unpurified gas 510 can correspond to a buffer gas flow carrying spent material (e g., a contaminant / impurity) from a plasma region in a light source system. Contaminant capture elements 504 can filter unpurified gas 510 to generate purified gas 512. The buffer gas flow being purified by a gas purification apparatus increases the longevity of an exhaust system by mitigating the rate of contaminant accumulation in downstream structures. In mitigating frequentmaintenance interruptions to contaminant-sensitive mechanisms, a lithographic apparatus can operate for longer periods of time, thereby increasing long-term throughput.

[0073] In some aspects, to ensure that unpurified gas 510 is effectively filtered, gaps where unpurified gas 510 can leak are sealed. As an example, a seal structure 522 is provided to ensure that the flow of unpurified gas 510 is directed to contaminant capture elements 504. Examples of seal structures can include an o-ring, a high-density metal mesh, or a suitable structure to block gas flow. Performance characteristics of contaminant capture elements 504 can depend on the dimensions of contaminant capture elements 504. The dimensions can include a length L of contaminant capture elements 504, a filter area A defined by the collection of contaminant capture elements 504, and a number N of contaminant capture elements 504 disposed in the flow path. Contaminant capture elements 504 can be structured as, for example, grill fins having length L (e.g., to increase capture area). A material of contaminant capture elements 504 can be matched to the type of contaminant in unpurified gas 510. For example, if the contaminant is expected to include tin, then the material of contaminant capture elements 504 can include molybdenum. Molybdenum can have desirable properties suitable for the capture of tin. Molybdenum is philic to tin (e.g., a tin “getter”), allowing for more effective purification. Molybdenum is also corrosion-resistant to liquid tin, which increases the lifetime of contaminant capture elements 504 in the service of filtering tin. Other materials for contaminant capture elements 504 are envisaged based on other contaminant types.

[0074] In some aspects, performance characteristics can include, for example, a rate of contaminant capture, quality of purification (e.g., level of remaining contamination in purified gas 512), gas flow rate (e.g., volume per unit time), and efficiency of space usage (e.g., volumetric efficiency). For effective filtration, a plane of contaminant capture elements 504 (e.g., the plane defined as having filter area A) can be disposed substantially normal or perpendicular to a drift direction of unpurified gas 504. It is to be appreciated that a microscopic view of the gas and contaminant particles may have random directions. Hence, the term “drift direction” can be used to refer to an average or general direction of the main flow (e.g., a direction bias according to a pressure differential or gradient).

[0075] In some aspects, volumetric optimization can be an important consideration in the design of source SO. A lithographic apparatus can be large and it is undesirable for source SO to also occupy a large footprint of valuable fab-facility floor space. Hence, source SO can have constrained volumetric and / or footprint budgets to optimize achieve full functionality using a smallest amount volume and / or area as possible. Therefore, the length L, the filter area A, and the number N of contaminant capture elements 504 can influence volumetric efficiency. For example, increasing the filter area A to increase filtering efficiency can be accompanied by undesirable increase of the volume occupied by gas purification apparatus 500. Aspects described herein (e.g., with respect to FIG. 6) provide structural features that increase filtering efficiency with reduced impact to the volume of a gas purification apparatus (or can be made even smaller).

[0076] In some aspects, contaminant capture elements 504 can comprise heated elements. Contaminant capture elements 504 can be heated using any suitable heating method. For example, contaminant capture elements 504 can comprise a conductive material through which electrical current can be transmitted to produce heat. In another example, pathway section 506 can comprise electrically and / or thermally conductive material (e.g., a heated liner) to function as a heat source and contaminant capture elements 504 can be thermally coupled to pathway section 506. The contaminant in unpurified gas 510 can be at solid phase (e g., at room temperature), but can have a melting point such that, when exposed to the heat from contaminant capture elements 504, the contaminant achieves a liquid phase. The liquid phase contaminant is illustrated as contaminant runoff 516.

[0077] In some aspects, contaminant runoff 516 in liquid phase can be influenced by a gravity vector 520. As a saturation prevention mechanism, a surface of gas purification apparatus 500 (e.g., pathway section 506) can be at an angle that is not horizontal with respect to a vertical gravity vector 520. Gravity can direct contaminant runoff 516 away from contaminant capture elements 504, thereby mitigating the accumulation of excess contaminant at contaminant capture elements 504.

[0078] In some aspects, contaminant capture elements 504 can be disposed at pathway section 506 pathway, which facilitates one or more desirable features. For example, the contaminant in unpurified gas 510 can be filtered out at an earlier portion of the flow stream, increasing the likelihood that the contaminant is stopped at contaminant capture elements 504 before the contaminant has a chance to settle on an unintended surface. In another example, if contaminant capture elements 504 are heated, the heat can be limited to pathway section 506. Heat can adversely affect the performance of the exhaust system, which can be a vacuum system. Furthermore, unpurified gas 510 and purified gas 512 can already be at an elevated temperature due to heat-generating processes in a radiation source (e.g., generating a hot plasma to generate radiation). To cool purified gas 512, gas cooling elements 518 can be disposed downstream of gas purification apparatus 500 (e.g., external to gas purification apparatus 500).

[0079] In some aspects, interface 514 can define an interface between two structures. Pathway section 506 may be on one side of interface 514 and conduit 508 may be on an opposite side of interface 514. Interface 514 can denote a boundary of source SO. Pathway section 506 can be a part of source SO. Pathway section 506 can be disposed inside or partially within source SO. In this scenario, maintenance actions to pathway section 506 (e.g., to replace saturated contaminant capture elements 504) can include removal of at least a portion of gas purification apparatus 500 from source SO. Removing at least a portion of gas purification apparatus 500 can include disassembly of at least a portion of source SO. Disassembly of a radiation source can be substantially complex and can cause prolonged downtime of the lithographic apparatus, thereby adversely impacting long-term wafer throughput.

[0080] FIG. 6 shows a gas purification apparatus 600, according to some aspects. In some aspects, gas purification apparatus 600 can be implemented in a lithographic apparatus. While gas purification600 has a different flow configuration compared to gas purification apparatus 500 (FIG. 5), some structures and functions can be common to both apparatuses. Unless otherwise noted, some of the structural and functional aspects of commonly numbered elements in FIGS. 5 and 6 can be as described above with respects to FIG. 5.

[0081] In some aspects, a gas pathway structure 602, a contaminant capture elements 604, a pathway section 606 are disposed separate from the radiation source (e.g., source SO). Gas pathway structure 602 can comprise pathway section 606 and a pathway section 624 (e.g., first and second pathway sections). A contaminant capture elements 604 can be disposed at pathway section 606. Gas pathway structure 602 can direct a flow of unpurified gas 610 via pathway section 606. Unpurified gas 610 can have a general drift direction (illustrated as downward in FIG. 6, as a non -limiting example).

[0082] In some aspects, another portion of contaminant capture elements 604 can be cylindrically arranged around an axis running substantially parallel to the drift direction of unpurified gas 610. While a simple cylinder is understood to have a circular base (e.g., circular cylinder), aspects disclosed herein can include other cylindrical arrangements, for example, a cylinder having an elliptical base (e.g., elliptical cylinder), a semi-circular base (e.g., half cylinder with a rounded lateral portion and a flat lateral portion), a rectangular base (e.g., rectangular cylinder), or the like. Cylindrical variants are not limited to arrangements of contaminant capture elements 604. For example, cylindrical variants are also envisaged for conduit structures for gas flow (e.g., gas pathway structures, pathway sections, turn sections, exhaust conduit, or the like).

[0083] In some aspects, the portion of contaminant capture elements 604 disposed along the plane that is substantially normal to a drift direction of unpurified gas 610 can define a filter area A. The portion can have N capture elements and each capture element can have a length L. In other approaches, increasing filter area and / or a number of capture elements to achieve a larger filtration area increases a diameter or width of gas pathway section 606, which is limited by the space constraints of source SO or prompt undesirable expansion of the footprint of source SO. To circumvent the problem of size constraint, the portion of contaminant capture elements 604 that are cylindrically arranged can be disposed to occupy a portion of an elongate conduit (e.g., pathway section 606). A consequence is that the additional number N' of capture elements and additional filter area A' can be significantly added without proportionally increasing a size (e.g., the diameter or width) of gas pathway 606, thereby mitigating undesirable expansion of apparatus footprint.

[0084] In some aspects, the arrows of unpurified gas 610' can represent a split of the main flow into smaller portions of contaminated gas, with the overall drift direction still being represented by the arrow of unpurified gas 610. The split in flow can be caused by the additional filter area A' and additional number N' of capture elements. Similarly the arrows of purified gas 612' can represent a split in the flow of purified gas caused by the increased filter area A' and additional number N’ of capture elements. The arrow of purified gas 612" can represent a drift direction of purified gas in pathway section 606 (e.g., parallel to the drift direction of unpurified gas 610). The arrow of purifiedgas 612'" can represent a drift direction of purified gas in turn section 626, at least some of which can be directed substantially normal to the drift directions of purified gas 612 and purified gas 612".

[0085] In some aspects, the increased filter area A+A' and increased number N+N’ of capture elements can be used to filter / purify unpurified gas 610 to generate purified gas 612 / 6127612'7612'". In this manner, filter capacity / rate is increased without significantly increasing a volume and / or footprint of gas purification apparatus 600.

[0086] In some aspects, gas cooling elements 618 can be disposed at second pathway section 624 and downstream of contaminant capture elements 604. Gas cooling elements 618 can cool purified gas 612 to prevent damage to further downstream mechanisms, such as the exhaust system. As a spacesaver feature, an orientation of pathway section 624 is such that a drift direction of purified gas 612 is different from the drift direction of the unpurified gas 610. Gas pathway 602 can comprise a turn section 626 that connects pathway sections 606 and 624. For clarity, an interface 628 illustrates an exemplary boundary between pathway sections 606 and 624 and turn section 626. Gas cooling elements 618 can be disposed downstream of the turn section 626. Turn section 626 can be structured to have a turn that is about 180 degrees (e.g., two 90 degree turns) such that the drift direction of purified gas 612 is opposite (e g., anti -parallel) to a drift direction of unpurified gas 610.

[0087] In some aspects, heat can be provided via a heating element 630 (e.g., heated liners) at the source-side of an interface 614. Contaminant capture elements 604 can be provided with alternative or additional heating methods as described above in reference to FIG. 5. Some contaminant runoff 616' can be generated at source-side. More contaminant runoff can be generated at contaminant capture elements 604. As a saturation prevention mechanism, a surface of gas purification apparatus 600 (e.g., pathway section 606) can be oriented with respect to a vertical gravity vector 620 such that contaminant runoff can flow. Contaminant runoff 616' can be combined with contaminant runoff from contaminant capture elements 604 to produce contaminant runoff 616. Gas purification apparatus 600 can also comprise a contaminant receiving structure 632 (e.g., a catching tray) to receive and collect condensation of contaminant or impurity material captured by contaminant capture elements 604. Contaminant receiving structure 632 can be disposed, for example, at turn section 626 — between pathway sections 606 and 624. Contaminant receiving structure 632 can be removable (e.g., via a port or window) to facilitate servicing and cleaning of gas purification apparatus 600.

[0088] For more space-usage optimization, pathway sections 606 and 624 can be nested structures or partially nested structures. For example, pathway sections 606 and 624 can be cylindrical or conical structures, one wider than the other. Pathway section 606 can be a first conduit structure that directs unpurified gas 610 through an interior of the first conduit structure. Pathway section 624 can be a second conduit structure disposed such that the first conduit structure is at least partially enclosed by the second conduit structure. The exterior wall of the first conduit structure can be an interior wall of the second conduit structure (e.g., a shared wall). Pathway section 624 can direct purified gas 612 in agap defined between the interior wall of the second conduit structure and the exterior wall of the first conduit structure.

[0089] In some aspects, gas purification apparatus 600 can be modular, which is facilitated by having the structures of gas purification apparatus 600 reside exterior to source SO with respect to interface 614. Gas purification apparatus 600 can also comprise a connection interface disposed at an inlet of gas purification apparatus 600. The connection interface allows gas purification apparatus 600 to be connected and disconnected from a host system (e g , source SO)

[0090] In some aspects, the present disclosure refers to gasses, gas flows, and gas purification. However, it is to be appreciated that gasses are a type of fluid and that the envisaged structures and functions of gas purification apparatuses disclosed herein are also applicable to fluids in general.

[0091] FIG. 7 shows a method 700 for performing functions as described in reference to FIGS. 1-6, according to some aspects. As an example, method operations will be described with reference to structures of a gas purification apparatus, which can also be referred to as a fluid purification apparatus.

[0092] In some aspects, at operation 702, an unpurified fluid (e.g., a purified gas) is directed via a fluid pathway structure (e.g., gas pathway structure) of the fluid purification apparatus. The unpurified fluid comprises a contaminant. The unpurified fluid is directed by flowing the unpurified fluid through one or more pathway sections of the fluid pathway structure comprising an array of contaminant capture elements. The direction of the unpurified fluid can be substantially normal or parallel to one or more planes defined by the array of contaminant capture elements.

[0093] In some aspects, at operation 704, a purified fluid (e.g., a flow of purified gas) is produced from the unpunfied fluid by capturing the contaminant using the contaminant capture elements.

[0094] In some aspects, at operation 706, the purified fluid is cooled using cooling elements at the one or more pathway sections of the fluid pathway structure and downstream of the contaminant capture elements.

[0095] In some aspects, at operation 708, optionally the purified fluid is directed such that a drift direction of the purified fluid at the cooling elements is different from the drift direction of the unpurified fluid at the plane.

[0096] In some aspects, at operation 710, condensation of material captured by the contaminant capture elements is received using a contamination receiving structure.

[0097] In some aspects, at operation 712, the unpurified fluid is generated at a system (e.g., generated at source SO).

[0098] The method operations of FIG. 7 can be performed in any conceivable order and it is not required that all steps be performed. Moreover, the method steps of FIG. 7 described above merely reflect an example of operations and are not limiting. That is, further method operations and functions are envisaged based aspects described in reference to FIGS. 1-7. For example, a connection interface of the fluid purification system is connected to the source SO.

[0099] Arrangements of components of gas purification apparatuses are not limited to those shown in FIGS. 5 and 6.

[0100] FIG. 8 shows gas purification apparatuses 802, 804, and 806, according to some aspects. In some aspects, gas purification apparatuses 802, 804, and 806 have different arrangements of elements described above in reference to FIGS. 5 and 6. Each of gas purification apparatuses 802, 804, and 806 can comprise a contaminant capture section 808, a cooling section 810, and a drainage section 812. Contaminant capture section 808 can comprise contaminant capture elements to purify an unpurified gas. Cooling section 810 can comprise cooling elements to cool the purified gas downstream of contaminant capture section 808. Drainage section 812 can comprise a contaminant receiving structure to catch contaminant runoff from contaminant capture section 808.

[0101] The gas path in gas purification apparatus 802 can be as follows. Unpurified gas 814 can be received as input into contaminant capture section 808 along the +x direction. Upon entry, unpurified gas 814 can be directed downward toward contaminant capture elements along the -z direction. After passing through contaminant capture elements, purified gas 816 can be directed toward the right along the y direction. In this arrangement, at least a portion of purified gas 816 can have a drift direction that is substantially perpendicular to at least a portion of unpurified gas 814.

[0102] The gas path in gas purification apparatus 804 can be as follows. Unpurified gas 814 can be received as input into contaminant capture section 808 along the +y direction. After passing through contaminant capture elements, purified gas 816 can be directed toward the right along the +y direction toward cooling section 810. In gas purification apparatus 804, cooling section 810 can be structured such that the path of purified gas 816 has multiple turns. In this arrangement, a portion of purified gas 816 can have a drift direction that is substantially perpendicular to at least a portion of unpurified gas 814 and another portion of purified gas 816 can have a drift direction that is substantially parallel to at least a portion of unpurified gas 814.

[0103] The gas path in gas purification apparatus 806 can be as follows. Unpurified gas 814 can be received as input into contaminant capture section 808 along the -z direction. After passing through contaminant capture elements, purified gas 816 can be directed toward the right along the +y direction toward cooling section 810. In gas purification apparatus 806, cooling section 810 can be structured such that the path of purified gas 816 has multiple turns. In this arrangement, a portion of purified gas 816 can have a drift direction that is substantially perpendicular to at least a portion of unpurified gas 814, another portion of purified gas 816 can have a drift direction that is substantially parallel to at least a portion of unpurified gas 814, and yet another portion of purified gas 816 can have a drift direction that is substantially antiparallel to unpurified gas 814. Furthermore, portions of purified gas 816 can drift antiparallel to one another. Described in cross-sectional terms, the path of purified gas 816 can be a zigzag or serpentine path.

[0104] The arrangements for gas purification apparatuses 802, 804, and 806 are provided as nonlimiting examples. Other arrangements are envisaged within the scope of aspects described herein.

[0105] The terms “radiation,” “beam,” “light,” “illumination,” or the like can be used herein to refer to one or more types of electromagnetic radiation, for example, ultraviolet (UV) radiation (for example, having a wavelength X of 365, 248, 193, 157 or 126 nm), extreme ultraviolet (EUV or soft X-ray) radiation (for example, having a wavelength in the range of 5-100 nm such as, for example, 13.5 nm), or hard X-ray working at less than 5 nm, as well as particle beams, such as ion beams or electron beams. Generally, radiation having wavelengths between about 400 to about 700 nm is considered visible radiation; radiation having wavelengths between about 780-3000 nm (or larger) is considered IR radiation. UV refers to radiation with wavelengths of approximately 100-400 nm. Within lithography, the term “UV” also applies to the wavelengths that can be produced by a mercury discharge lamp: G-line 436 nm; H-line 405 nm; and / or, I-line 365 nm. Vacuum UV, or VUV (i.e., UV absorbed by gas), refers to radiation having a wavelength of approximately 100-200 nm.

[0106] It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by those skilled in relevant art(s) in light of the teachings herein.

[0107] The present disclosure has been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed. The foregoing description of specific aspects will so fully reveal the general nature of the present disclosure that others can, by applying knowledge within the skill of the art, readily modify and / or adapt for various applications such specific aspects, without undue experimentation and without departing from the general concept of the present disclosure. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed aspects, based on the teaching and guidance presented herein.

[0108] It is to be understood that the Detailed Description section, and not the Summary and Abstract sections, is intended to be used to interpret the claims. The Summary and Abstract sections can set forth one or more, but not necessarily all, aspects of the present disclosure as contemplated by the inventor(s), and thus, are not intended to limit the present disclosure and the appended claims in any way. The breadth and scope of the protected subject matter should not be limited by any of the abovedescribed aspects, but should be defined in accordance with the following claims and their equivalents.

Claims

CLAIMS1. A radiation source comprising: a chamber comprising an irradiation region; and a gas purification apparatus coupled to the chamber and comprising a gas pathway structure configured to direct an unpurified gas having contaminants, the gas pathway structure comprising: a first pathway section comprising contaminant capture elements, wherein: the contaminant capture elements are configured to capture the contaminant to produce purified gas, and at least a portion of the contaminant capture elements are disposed along a plane that is substantially normal to a drift direction of the unpurified gas at the plane; and a second pathway section comprising gas cooling elements disposed downstream of the contaminant capture elements, wherein: the gas cooling elements are configured to cool the purified gas, and an orientation of the second pathway section is such that a drift direction of the purified gas is different from the drift direction of the unpurified gas.

2. The radiation source of claim 1, wherein: the first pathway section comprises a first conduit structure configured to direct the unpurified gas through an interior of the first conduit structure, and the second pathway section comprises a second conduit structure disposed such that the first conduit structure is at least partially enclosed by the second conduit structure.

3. The radiation source of claim 2, wherein: the second conduit structure comprises a second cylinder; and the first conduit structure is a first cylinder nested in the second cylinder.

4. The radiation source of claim 2, wherein the second pathway section is configured to direct the purified gas in a gap defined between an interior wall of the second conduit structure and an exterior wall of the first conduit structure.

5. The radiation source of claim 1, wherein: the gas pathway structure further comprises a turn section that connects the first pathway section and the second pathway section, and the gas cooling elements are disposed downstream of the turn section such that the drift direction of the purified gas is opposite the drift direction of the unpurified gas.

6. The radiation source of claim 1, wherein the gas purification apparatus further comprises a contamination receiving structure configured to receive condensation of material captured by the contaminant capture elements, wherein the contamination receiving structure is positioned between the first pathway section and the second pathway section.

7. The radiation source of claim 1, wherein the gas purification apparatus further comprises a connection interface disposed at an inlet of the gas purification apparatus, wherein the gas purification apparatus is modular.

8. The radiation source of claim 1, wherein another portion of the contaminant capture elements are cylindrically arranged around an axis running parallel to the drift direction of the unpurified gas.

9. A gas purification apparatus comprising: a gas pathway structure configured to direct an unpurified gas comprising an impurity, the gas pathway structure comprising: a first pathway section comprising impurity capture elements, wherein: the impurity capture elements are configured to capture the impurity to produce purified gas, and at least a portion of the impurity capture elements are disposed along one or more planes, wherein a plane of the one or more planes is substantially normal or parallel to a drift direction of the unpurified gas at the plane; and a second pathway section comprising gas cooling elements disposed downstream of the impurity capture elements, wherein: an orientation of the second pathway section is such that a drift direction of the purified gas is different from the drift direction of the unpurified gas.

10. The gas purification apparatus of claim 9, wherein: the first pathway section comprises a first conduit structure, and the second pathway section comprises a second conduit structure disposed such that the first conduit structure is at least partially enclosed by the second conduit structure.

11. The gas purification apparatus of claim 10, wherein: the second conduit structure comprises a second cylinder; the first conduit structure is a first cylinder nested in the second cylinder; the gas pathway structure comprises a turn section that connects the first cylinder and the second cylinder.

12. The gas purification apparatus of claim 10, wherein the second pathway section is configured to direct the purified gas in a gap defined between an interior wall of the second conduit structure and an exterior wall of the first conduit structure.

13. The gas purification apparatus of claim 9, wherein: the gas pathway structure further comprises a turn section that connects the first pathway section and the second pathway section, and the gas cooling elements are disposed downstream of the turn section such that the drift direction of the purified gas in the turn section is substantially normal to the drift direction of the unpurified gas.

14. The gas purification apparatus of claim 9, further comprising a contamination receiving structure positioned in an interior of the gas purification apparatus.

15. The gas purification apparatus of claim 9, further comprising: a connection interface disposed at an inlet of the gas purification apparatus, wherein the gas purification apparatus is coupled to a heating element.

16. The gas purification apparatus of claim 9, wherein another portion of the contaminant capture elements are cylindrically arranged around an axis running parallel to the drift direction of the unpurified gas.

17. A method comprising: directing an unpurified fluid via a fluid pathway structure of a fluid purification apparatus, wherein: the unpurified fluid comprises a contaminant, and the directing comprises flowing the unpurified fluid through a first pathway section of the fluid pathway structure such that a drift direction of the unpurified fluid is substantially normal to a plane defined by an array of contaminant capture elements; producing purified fluid from the unpurified fluid, the producing comprising capturing the contaminant using contaminant capture elements, cooling the purified fluid using cooling elements disposed at a second pathway section of the gas pathway structure and downstream of the contaminant capture elements; and directing the purified fluid such that a drift direction of the purified fluid at the cooling elements is different from the drift direction of the unpurified fluid at the plane.

18. The method of claim 17, wherein:the second conduit structure comprises a second cylinder; and the first conduit structure is a first cylinder nested in the second cylinder, wherein an exterior wall of the first cylinder is a shared wall with the second cylinder.

19. The method of claim 17, further comprising receiving condensation of the contaminant captured by the contaminant capture elements using a contamination receiving structure.

20. The method of claim 17, further comprising: generating the unpurified fluid from an interior of a radiation source chamber; coupling the fluid purification apparatus to the radiation source chamber.

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