Adjustable cathode for life extension in excimer laser discharge chambers

Abstract

A light source includes a chamber, a first electrode assembly, and a second electrode. The first electrode assembly includes a first electrode, a rod, and a tip portion. The rod extends longitudinally through a portion of the first electrode. The tip portion is coupled to the rod and includes a first discharge surface. The second electrode has a second discharge surface spaced apart from the first discharge surface by a discharge gap. The rod adjusts a position of the tip portion to maintain the discharge gap. The first and second electrodes excite a gas discharge medium of the chamber to generate a light beam. Advantageously, the system maintains the discharge gap over time, maintains flow between the discharge gap, adjusts a position of the first discharge surface based on one or more parameters of the light source, reduces errors in the light beam, and increases lifetime of the light source.

Description

2023P00384W001 1ADJUSTABLE CATHODE FOR LIFE EXTENSION IN EXCIMER LASER DISCHARGE CHAMBERSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of US Application No. 63 / 737,047, which was filed on December 20, 2024, US Application No. 63 / 802,022, which was filed on May 8, 2025, and US Application No. 63 / 925,628, which was filed on November 26, 2025, which are incorporated herein by reference in their entireties.FIELD

[0002] The present disclosure relates to light source apparatuses, systems, and methods, for example, light source apparatuses, systems, and methods to maintain or adjust a discharge gap of a gas discharge chamber over time and to control gas flow through the discharge gap over time.BACKGROUND

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

[0004] To project a pattern on a substrate a lithographic apparatus may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features which can be formed on the substrate. A lithographic apparatus, which uses deep ultraviolet (DUV) radiation, having a wavelength within the range 100-400 nanometers (nm), for example 193 nm or 248 nm, may be used to form features on a substrate.

[0005] Since errors and contamination occur during processing of the substrate, a metrology / inspection apparatus may be used to detect the manufacturing errors, identify contaminants, and / or measure critical dimensions. In some instances, a light source that generates DUV radiation may be employed in the metrology / inspection apparatus.

[0006] A master oscillator power amplifier (MOPA) or a master oscillator power ring amplifier (MOPRA) is a two-stage (two-chamber) optical resonator arrangement that produces a highly coherent amplified light beam. The performance of the MOPA or the MOPRA can depend critically on the master oscillator (MO), the power amplifier (PA), and / or the power ring amplifier (PRA). Gas discharge chambers (e.g., MO chamber) have limited lifetime due to various performance issues (e.g., electrode erosion, gas mixture degradation, impurity accumulation, optical window damage, etc.), and replacement can be time-consuming and costly. Electrode erosion can impose significant limits on the useful lifetime of a gas discharge chamber, and can lead to both an increase in a discharge gap between electrodes of the gas discharge chamber and broadening of the generated discharge. As the electrodes2023P00384W001 2 erode, the discharge gap can increase to the point where operational characteristics of the light source are so severely affected that light beam operation must be stopped.

[0007] Currently, some systems utilize one or more movable electrodes to compensate for electrode erosion over time and attempt to control the discharge gap. However, some gas discharge chambers have slower or faster electrode erosion rates than others, and an average erosion rate may not be reliable as a metric. Also, some gas discharge chambers may use a stationary electrode (e.g., a stationary cathode), whose erosion over time can lead to an increase in the discharge gap as well as turbulent or irregular flow (e.g., non-laminar) of the gas discharge medium in the discharge gap. Further, current systems may not actively measure an electrode position (e.g., a cathode position) over time and, thus, may not maintain an accurate discharge gap over time or appropriate flow in the discharge gap over time. Additionally, current systems may not be capable of simultaneous adjustment of both electrodes to maintain an accurate discharge gap over time.SUMMARY

[0008] Accordingly, there is a need to, e.g., actively maintain a discharge gap over time to increase lifetime of an excimer light source. Further, there is a need to actively maintain flow between the discharge gap (e.g., maintain laminar flow). Further, there is a need to simultaneously adjust actuators associated with an anode and a cathode (e.g., based on a predetermined ratio). Further, there is a need to provide feedback to a controller (e.g., via a feedback loop) to adjust one or more actuators over time based on one or more parameters of a light source (e.g., position of cathode, erosion rate of cathode, position of anode, erosion rate of anode, etc.). This novel approach can increase lifetime of an excimer light source (e.g., greater than 120 billion pulses (Bp)). Further, this novel approach can reduce errors in the generated light beam. Further, this novel approach can reduce errors in a lithographic process. Further, this novel approach can perform diagnostics of the light source. Further, this novel approach can maintain laminar flow of a gas discharge medium in the discharge gap. Further, this novel approach can allow for higher pulse repetition rates (e.g., faster than 1 kHz).

[0009] In some embodiments, a light source may include a chamber, a first electrode, a second electrode, and an actuator. In some embodiments, the chamber is configured to house a gas discharge medium. In some embodiments, the first electrode may include a first discharge surface. In some embodiments, the second electrode may be opposite the first electrode. In some embodiments, the second electrode may include a second discharge surface. In some embodiments, the second discharge surface may be spaced apart from the first discharge surface by a discharge gap. In some embodiments, the actuator may be coupled to the first electrode. In some embodiments, the actuator may be configured to move with the first discharge surface. In some embodiments, the first and second electrodes may be configured to excite the gas discharge medium and generate a light beam.

[0010] In some embodiments, the actuator may include a flow control surface adjacent the first discharge surface. In some embodiments, the actuator may be configured to maintain flow between the2023P00384W001 3 flow control surface and the first discharge surface. In some embodiments, the flow control surface may be configured to maintain laminar flow between the discharge gap.

[0011] In some embodiments, the flow control surface may include an overhang. In some embodiments, the overhang may include a fairing adjacent the first discharge surface. In some embodiments, the actuator may be configured to be parallel with the first discharge surface. In some embodiments, the flow control surface may include a preionization tube. In some embodiments, the preionization tube may include a surface having a teardrop shape. In some embodiments, the actuator may include one or more flow control surfaces adjacent the first discharge surface. In some embodiments, the one or more flow control surfaces may include an overhang, a preionization tube, or a combination thereof.

[0012] In some embodiments, the light source may further include a controller coupled to the actuator. In some embodiments, the controller may be configured to adjust a position of the actuator based on a measured parameter of the first electrode. In some embodiments, the measured parameter may include an erosion rate of the first electrode over time. In some embodiments, the controller may be configured to adjust the actuator continuously over time. In some embodiments, the controller may be configured to adjust the actuator based on a first predetermined rate of erosion of the first electrode and a second predetermined rate of erosion of the second electrode.

[0013] In some embodiments, the actuator may be configured to compensate for erosion of the first electrode over time to increase a lifetime of the light source.

[0014] In some embodiments, the actuator may include a gear coupled to a motor and the overhang. In some embodiments, the gear may be configured to adjust the overhang to be flush with the first discharge surface based on a gear ratio. In some embodiments, the gear ratio may be based on an erosion rate of the first electrode.

[0015] In some embodiments, the actuator may include a spring coupled to the overhang. In some embodiments, the spring may be configured to provide a restoring force to the overhang such that the overhang is flush with the first discharge surface. In some embodiments, the light source may further include a controller coupled to the actuator and configured to adjust a tension of the spring to adjust a position of the overhang over time. In some embodiments, the actuator may include a support coupled to a motor and the overhang. In some embodiments, the support may be configured to adjust the restoring force of the spring by a predetermined amount. In some embodiments, the predetermined amount may be based on an erosion rate of the first electrode overtime.

[0016] In some embodiments, the light source may further include a second actuator coupled to the second electrode. In some embodiments, the second actuator may be configured to adjust a position of the second discharge surface to maintain the discharge gap. In some embodiments, the second actuator may be coupled to the actuator. In some embodiments, the light source may further include a controller coupled to the actuator and the second actuator. In some embodiments, the controller may be configured to adjust a position of the actuator based on a measured parameter of the first electrode. In some2023P00384W001 4 embodiments, the controller may be configured to simultaneously adjust the second actuator to maintain the discharge gap based on the measured parameter of the first electrode.

[0017] In some embodiments, a method of controlling operation of a light source may include measuring a parameter of the light source. In some embodiments, the light source may include an optical amplifier configured to output a light beam. In some embodiments, the optical amplifier may include a discharge chamber, a movable electrode assembly, and a movable flow control assembly. In some embodiments, the method may include measuring a parameter of the optical amplifier. In some embodiments, the method may include adjusting a position of the movable flow control assembly based on the measured parameter to reduce errors in the light beam.

[0018] In some embodiments, the adjusting the position of the movable flow control assembly may include adjusting a position of one or more flow control surfaces with one or more actuators based on the measured parameter. In some embodiments, the adjusting the position of the one or more flow control surfaces may include maintaining flow between the one or more flow control surfaces and a first discharge surface of the movable electrode assembly. In some embodiments, the maintaining flow between the one or more flow control surfaces and the first discharge surface may include maintaining laminar flow.

[0019] In some embodiments, the adjusting the position of the one or more flow control surfaces with the one or more actuators may include adjusting the position of the one or more flow control surfaces such that the one or more flow control surfaces is flush with a first discharge surface of the movable electrode assembly. In some embodiments, the adjusting the position of the one or more flow control surfaces such that the one or more flow control surfaces is flush with the first discharge surface may include adjusting the position of the one or more flow control surfaces periodically or continuously over time.

[0020] In some embodiments, the one or more flow control surfaces may include an overhang, a preionization tube, or a combination thereof.

[0021] In some embodiments, the measuring the parameter may include measuring a parameter of the moveable electrode assembly. In some embodiments, the measuring the parameter may include measuring an erosion rate of a first electrode of the movable electrode assembly.

[0022] In some embodiments, the method may further include adjusting a discharge gap between a first electrode and a second electrode of the movable electrode assembly based on the measured parameter. In some embodiments, the method may be configured to increase a lifetime of the light source. In some embodiments, the method may be configured to compensate for erosion of the first electrode over time to increase a lifetime of the light source .

[0023] In some embodiments, a light source may include a chamber, a first electrode, a second electrode, and an actuator. In some embodiments, the chamber may be configured to house a gas discharge medium. In some embodiments, the first electrode may include a first discharge surface. In some embodiments, the second electrode may be disposed opposite of the first electrode. In some2023P00384W001 5 embodiments, the second electrode may include a second discharge surface. In some embodiments, the second discharge surface may be spaced apart from the first discharge surface by a discharge gap. In some embodiments, the actuator may be coupled to the first electrode. In some embodiments, the actuator may be configured to move the first discharge surface to maintain the discharge gap. In some embodiments, the first and second electrodes may be configured to excite the gas discharge medium and generate a light beam.

[0024] In some embodiments, the actuator may be configured to maintain flow of the gas discharge medium between the first and second discharge surfaces. In some embodiments, the actuator may be configured to maintain laminar flow of the gas discharge medium between the discharge gap.

[0025] In some embodiments, the actuator may be configured to compensate for erosion of the first electrode overtime to increase the lifetime of the light source.

[0026] In some embodiments, the actuator may include a support coupled to a motor. In some embodiments, the support may be configured to adjust a position of the first discharge surface. In some embodiments, the support may be configured to adjust the position of the first discharge surface based on a predetermined ratio. In some embodiments, the support may include a control surface. In some embodiments, the predetermined ratio may be based on an opening angle of the control surface. In some embodiments, the predetermined ratio may be based on an erosion rate of the first electrode.

[0027] In some embodiments, the actuator may include a transducer coupled to the first electrode. In some embodiments, the transducer may be configured to provide a restoring force to the first electrode to move the first discharge surface towards the second discharge surface. In some embodiments, the transducer may include an elevator mechanism. In some embodiments, the elevator mechanism may be pre-loaded.

[0028] In some embodiments, the elevator mechanism may include one or more teeth on the first electrode and a support with one or more grooves coupled to the one or more teeth. In some embodiments, the elevator mechanism may be pre-loaded such that as the support moves relative to the first electrode, the restoring force is applied to the first electrode and the first discharge surface protrudes towards the second discharge surface. In some embodiments, the elevator mechanism may be pre- loaded with one or more springs configured to apply an outward force to the first electrode. In some embodiments, the elevator mechanism may be magnetically pre-loaded to apply an outward force to the first electrode. For example, the elevator mechanism may include one or more magnets (e.g., permanent magnets, electromagnets, etc.) configured to apply the outward force to the first electrode.

[0029] In some embodiments, the light source may further include a controller coupled to the actuator. In some embodiments, the controller may be configured to perform operations including adjusting a position of the actuator relative to the first electrode to adjust a position of the first discharge surface over time. In some embodiments, the actuator may include a support coupled to a motor. In some embodiments, the support may be configured to adjust a restoring force of a transducer coupled to the2023P00384W001 6 first electrode by a predetermined amount. In some embodiments, the predetermined amount may be based on an erosion rate of the first electrode over time.

[0030] In some embodiments, the controller may be configured to perform operations including adjusting a position of the actuator based on a parameter of the first electrode. In some embodiments, the parameter may include an erosion rate of the first electrode over time. In some embodiments, the operations may further include adjusting the actuator continuously over time. In some embodiments, the operations may further include adjusting the actuator based on a first rate of erosion of the first electrode and a second rate of erosion of the second electrode.

[0031] In some embodiments, the light source may further include a second actuator coupled to the second electrode. In some embodiments, the second actuator may be configured to adjust a position of the second discharge surface to maintain the discharge gap. In some embodiments, the second actuator may be coupled to the actuator. In some embodiments, the light source may further include a controller coupled to the actuator and the second actuator. In some embodiments, the controller may be configured to perform operations including adjusting a position of the actuator based on a parameter of the first electrode. In some embodiments, the operations may further include simultaneously adjusting the second actuator to maintain the discharge gap based on the parameter of the first electrode.

[0032] In some embodiments, a method of controlling operation of a light source may include determining a parameter of the light source. In some embodiments, the light source may include an optical amplifier configured to output a light beam. In some embodiments, the optical amplifier may include a discharge chamber and a movable electrode assembly. In some embodiments, the method may include determining a parameter of the optical amplifier. In some embodiments, the method may include adjusting a position of the movable electrode assembly based on the parameter to reduce errors in the light beam.

[0033] In some embodiments, the adjusting the position of the movable electrode assembly may include adjusting a position of one or more electrodes with one or more actuators based on the parameter. In some embodiments, the adjusting the position of the moveable electrode assembly may include maintaining flow between a first discharge surface and a second discharge surface of the movable electrode assembly.

[0034] In some embodiments, the adjusting the position of the one or more electrodes with the one or more actuators may include adjusting a first position of the first discharge surface. In some embodiments, the adjusting the position of the one or more electrodes with the one or more actuators may further include simultaneously adjusting a second position of the second discharge surface. In some embodiments, the adjusting the position of the one or more electrodes with the one or more actuators may include adjusting the first and second positions of the first and second discharge surfaces periodically or continuously over time based on the parameter to maintain a discharge gap between the first and second discharge surfaces.2023P00384W001 7

[0035] In some embodiments, a discharge gap between the first and second discharge surfaces may be maintained by one or more control signals from a controller (e.g., in a closed-loop feedback algorithm) based on one or more parameters. In some embodiments, the one or more control signals may be based on a chamber operating pressure of a gas discharge medium of the light source. In some embodiments, the one or more control signals may be based on a blower current signal of a motor coupled to a blower assembly of the light source. In some embodiments, the one or more control signals may be based on a capacitor voltage waveform of one or first plurality of capacitors and / or one or second plurality of capacitors coupled to the movable electrode assembly.

[0036] In some embodiments, the one or more control signals may be based on direct imaging of the discharge gap. For example, one or more light detectors may directly image and measure the discharge gap over time. In some embodiments, the controller may correlate a change in the image to a change in the discharge gap.

[0037] In some embodiments, the one or more control signals may be based on voltage feedback of the movable electrode assembly. For example, the one or more control signals may be based on a change in the interelectrode voltage (e.g., voltage across discharge gap). In some embodiments, the controller may correlate a change in the interelectrode voltage to a change in the discharge gap.

[0038] In some embodiments, the one or more control signals may be based on correlated velocity measurements (e.g., flow speed) of a gas discharge medium of the light source. For example, the light source may include one or more pitot tubes placed downstream of the discharge gap that measure a change in turbulence or flow separation of the gas discharge medium. In some embodiments, the controller may correlate a change in turbulence or flow separation of the gas discharge medium (e.g., via one or more pitot tubes) to a change in the discharge gap.

[0039] In some embodiments, the method may be configured to compensate for erosion of the first electrode overtime to increase the lifetime of the light source.

[0040] In some embodiments, a light source may include a chamber, a first electrode assembly, and a second electrode. In some embodiments, the chamber is configured to house a gas discharge medium. In some embodiments, the first electrode assembly has a first discharge surface. In some embodiments, the first electrode assembly include a first electrode, a rod, and a tip portion. In some embodiments, the first electrode is coupled to a power source. In some embodiments, the rod has a proximal end and a distal end. In some embodiments, the rod extends longitudinally through a portion of the first electrode. In some embodiments, the tip portion is coupled to the distal end of the rod. In some embodiments, the tip portion includes the first discharge surface. In some embodiments, the second electrode is disposed opposite of the first electrode assembly. In some embodiments, the second electrode has a second discharge surface. In some embodiments, the second discharge surface is spaced apart from the first discharge surface by a discharge gap. In some embodiments, the rod is configured to adjust a position of the tip portion to maintain the discharge gap. In some embodiments, the first and second electrodes are configured to excite the gas discharge medium and to generate a light beam.2023P00384W001 8

[0041] In some embodiments, the rod extends through a longitudinal bore of the first electrode. In some embodiments, the rod is configured to translate along the longitudinal bore. In some embodiments, when the rod is translated along the longitudinal bore, the rod adjusts a position of the first discharge surface of the tip portion to maintain the discharge gap. In some embodiments, the rod includes a screw configured to interlock with the tip portion. In some embodiments, when the rod is rotated within the longitudinal bore, the rod adjusts a position of the first discharge surface of the tip portion to maintain the discharge gap.

[0042] In some embodiments, the first electrode assembly further includes a gasket between the first electrode and the rod. In some embodiments, the gasket is configured to maintain a pressure of the chamber. In some embodiments, the gasket may include an O-ring.

[0043] In some embodiments, the first electrode assembly further includes a conductive flexure disposed between the first electrode and the tip portion. In some embodiments, the conductive flexure is configured to maintain electrical connection between the first electrode and the tip portion. In some embodiments, the conductive flexure is configured to apply an upward restoring force to the rod. In some embodiments, the first electrode assembly further includes one or more screws coupled to the conductive flexure. In some embodiments, the one or more screws are configured to adjust a position of the conductive flexure.

[0044] In some embodiments, the first electrode assembly further includes a plug coupled to the proximal end of the rod. In some embodiments, the plug is configured to adjust a position of the first discharge surface of the tip portion. In some embodiments, the plug includes a precision length tip configured to adjust a length of the rod and thereby adjust a position of the first discharge surface of the tip portion to maintain the discharge gap. In some embodiments, the plug may include one or more precision length tips each configured to adjust a length of the rod by a different amount (e.g., 1 mm, 2 mm, 3 mm, etc.) and thereby adjust a position of the first discharge surface of the tip portion, respectively.

[0045] In some embodiments, the first electrode assembly further includes an actuator coupled to the proximal end of the rod. In some embodiments, the actuator is configured to adjust a position of the first discharge surface of the tip portion to maintain the discharge gap. In some embodiments, the actuator is electrically insulated from the first electrode. In some embodiments, the actuator is configured to adjust the position of the first discharge surface of the tip portion based on a predetermined ratio. In some embodiments, the actuator may include a mechanical (non-electric) actuator (e.g., manual adjuster, precision micrometer head, precision adjustment screw, cam, pneumatic, hydraulic, magnetic, etc.).

[0046] In some embodiments, an electrode assembly for a light source may include an electrode, a rod, and a tip portion. In some embodiments, the electrode is coupled to a power source. In some embodiments, the rod extends longitudinally through a portion of the electrode. In some embodiments,2023P00384W001 9 the tip portion is coupled to the rod. In some embodiments, the tip portion includes a discharge surface. In some embodiments, the rod is configured to adjust a position of the discharge surface.

[0047] In some embodiments, the electrode assembly may further include a second electrode disposed opposite of the tip portion and having a second discharge surface. In some embodiments, the second discharge surface is spaced apart from the discharge surface by a discharge gap.

[0048] In some embodiments, the rod is configured to extend through a longitudinal bore of the electrode. In some embodiments, the rod is configured to translate along the longitudinal bore and, when the rod is translated, thereby adjust the position of the discharge surface of the tip portion. In some embodiments, the rod includes a screw configured to interlock with the tip portion and, when the rod is rotated, thereby adjust the position of the discharge surface of the tip portion.

[0049] In some embodiments, the electrode assembly may further include a conductive flexure disposed between the electrode and the tip portion. In some embodiments, the conductive flexure is configured to maintain electrical connection between the electrode and the tip portion. In some embodiments, the conductive flexure is configured to apply an upward restoring force to the rod.

[0050] In some embodiments, the electrode assembly may further include an actuator coupled to the rod and configured to adjust the position of the discharge surface of the tip portion.

[0051] In some embodiments, a method of controlling operation of a light source may include determining a number of pulses generated by the light source. In some embodiments, the light source may include a chamber configured to house a gas discharge medium, a first electrode assembly having a first discharge surface, and a second electrode having a second discharge surface. In some embodiments, the second discharge surface is spaced apart from the first discharge surface by a discharge gap. In some embodiments, the first and second electrodes are configured to excite the gas discharge medium and generate a light beam. In some embodiments, the method may further include adjusting a position of the first discharge surface based on the number of pulses to adjust the discharge gap-

[0052] In some embodiments, the adjusting the position of the first discharge surface may include translating a rod of the first electrode assembly along a longitudinal bore of a first electrode of the first electrode assembly. In some embodiments, the adjusting the position of the first discharge surface may include rotating a rod of the first electrode assembly within a longitudinal bore of a first electrode of the first electrode assembly.

[0053] In some embodiments, the adjusting the position of the first discharge surface may include inserting a plug into a longitudinal bore of a first electrode of the first electrode assembly. In some embodiments, the plug may include a precision length tip configured to adjust a length of a rod of the first electrode assembly.

[0054] In some embodiments, the adjusting the position of the first discharge surface may include adjusting a rod of the first electrode assembly with an actuator based on a predetermined ratio. In some embodiments, the predetermined ratio is based on an erosion rate of the first electrode. In some2023P00384W001 10 embodiments, the predetermined ratio is based on a first rate of erosion of the first electrode and a second rate of erosion of the second electrode.

[0055] In some embodiments, the method may further include adjusting a position of the second discharge surface based on the number of pulses to adjust the discharge gap.

[0056] Implementations of any of the techniques described above may include a DUV light source, a system, an apparatus, a device, a method, a process, and / or a computer program product. The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

[0057] Further features and example embodiments of the present disclosure, as well as the structure and operation of various embodiments, are described in detail below with reference to the accompanying drawings. It is noted that the embodiments are not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein.BRIEF DESCRIPTION OF THE DRAWINGS / FIGURES

[0058] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the embodiments and, together with the description, further serve to explain the principles of the embodiments and to enable a person skilled in the relevant art(s) to make and use the embodiments.

[0059] FIG. 1 is a schematic illustration of a lithography system, according to an example embodiment.

[0060] FIG. 2 is a schematic illustration of a light source, according to an example embodiment.

[0061] FIG. 3 is a cross-sectional schematic illustration of a gas discharge chamber, according to an example embodiment.

[0062] FIG. 4 is front schematic illustration of a gas discharge chamber with a flow control assembly, according to an example embodiment.

[0063] FIG. 5 is a perspective schematic illustration of the flow control assembly shown in FIG. 4, according to an example embodiment.

[0064] FIG. 6 is a front schematic illustration of a gas discharge chamber with a flow control assembly, according to an example embodiment.

[0065] FIG. 7 is a front schematic illustration of a gas discharge chamber with a flow control assembly, according to an example embodiment.

[0066] FIG. 8 is a front schematic illustration of a gas discharge chamber with a flow control assembly, according to an example embodiment.

[0067] FIG. 9 illustrates a flow diagram for a light source, according to an example embodiment.

[0068] FIG. 10 is a front schematic illustration of a gas discharge chamber with an actuator assembly, according to an example embodiment.2023P00384W001 11

[0069] FIG. 11 is a perspective schematic illustration of the actuator assembly coupled to a cathode assembly of the gas discharge chamber shown in FIG. 10, according to an example embodiment.

[0070] FIG. 12 is a perspective schematic illustration of an actuator assembly coupled to a cathode assembly of the gas discharge chamber shown in FIG. 10, according to an example embodiment.

[0071] FIG. 13 is a perspective schematic illustration of an actuator assembly coupled to a cathode assembly of the gas discharge chamber shown in FIG. 10, according to an example embodiment.

[0072] FIG. 13A is a cross-sectional view of a conductive flexure coupled to an actuator assembly and an electrode assembly of a gas discharge chamber, according to an example embodiment.

[0073] FIG. 14 illustrates a flow diagram for a light source, according to an example embodiment.

[0074] FIG. 15 is a front schematic illustration of a gas discharge chamber with a cathode assembly, according to an example embodiment.

[0075] FIG. 16 is a front schematic illustration of a gas discharge chamber with a cathode assembly, according to an example embodiment.

[0076] FIG. 17 is a front schematic illustration of a gas discharge chamber with a cathode assembly, according to an example embodiment.

[0077] FIG. 18 is a front schematic illustration of a gas discharge chamber with a cathode assembly, according to an example embodiment.

[0078] FIG. 19 is a front schematic illustration of a gas discharge chamber with a cathode assembly, according to an example embodiment.

[0079] FIG. 20 illustrates a flow diagram for a light source, according to an example embodiment.

[0080] FIG. 21A is a cross-sectional view of an actuator assembly and an electrode assembly of a gas discharge chamber, according to an example embodiment.

[0081] FIG. 2 IB is a cross-sectional view of an actuator assembly and an electrode assembly of a gas discharge chamber, according to an example embodiment.

[0082] FIG. 21C is a cross-sectional view of an actuator assembly and an electrode assembly of a gas discharge chamber, according to an example embodiment.

[0083] FIG. 2 ID is a cross-sectional view of an actuator assembly and an electrode assembly of a gas discharge chamber, according to an example embodiment.

[0084] FIG. 22 is a schematic illustration of a computing system, according to an example embodiment.

[0085] The features and example embodiments 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.2023P00384W001 12DETAILED DESCRIPTION

[0086] Provided herein are system, apparatus, device, method, process, and / or computer program product embodiments, and / or combinations and sub -combinations thereof, for maintaining or adjusting a discharge gap of a gas discharge chamber of a light source over time and for controlling gas flow through the discharge gap over time that can be used, for example, for a lithographic process.

[0087] A light source as described below includes a chamber housing a gas discharge medium, a first electrode having a first discharge surface, a second electrode having a second discharge surface spaced apart from the first discharge surface by a discharge gap, and a flow control assembly (e.g., overhang, fairing, preionization tube) relative to the first discharge surface to maintain flow (e.g., laminar flow) between the discharge gap.

[0088] A light source as described below includes a chamber housing a gas discharge medium, an electrode assembly having first and second electrodes spaced apart by a discharge gap and configured to excite the gas discharge medium to generate a light beam, and an actuator coupled to the first electrode and configured to adjust a position of the first electrode to maintain the discharge gap.

[0089] A light source as described below includes a chamber housing a gas discharge medium, a first electrode assembly having a first electrode, a rod, and a tip portion having a first discharge surface, and a second electrode having a second discharge surface spaced apart from the first discharge surface by a discharge gap, the rod extending through a portion of the first electrode and configured to adjust a position of the tip portion to maintain the discharge gap.

[0090] This specification discloses one or more embodiments that incorporate the features of this present disclosure.

[0091] The embodiment(s) described, and references in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” “an exemplary embodiment,” etc., indicate that the embodiment(s) described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is understood that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0092] Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “on,” “upper” and the like, may 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 may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0093] The term “about” or “substantially” or “approximately” as used herein indicates the value of a given quantity that can vary based on a particular technology. Based on the particular technology, the2023P00384W001 13 term “about” or “substantially” or “approximately” can indicate a value of a given quantity that varies within, for example, 1-15% of the value (e.g., ±1%, ±2%, ±5%, ±10%, or ±15% of the value).

[0094] Numerical values, including endpoints of ranges, can be expressed herein as approximations preceded by the term “about,” “substantially,” “approximately,” or the like. In such cases, other embodiments include the particular numerical values. Regardless of whether a numerical value is expressed as an approximation, two embodiments are included in this disclosure: one expressed as an approximation, and another not expressed as an approximation. It will be further understood that an endpoint of each range is significant both in relation to another endpoint, and independently of another endpoint.

[0095] Embodiments of the disclosure may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the disclosure may also be implemented as instructions stored on a machine -readable medium (e.g., memory), which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine- readable medium may include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.); and others. Further, firmware, software, routines, and / or instructions may be described herein as performing certain actions. However, it should be appreciated that such descriptions are merely for convenience and that such actions in fact result from computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc. The term “machine -readable medium” may 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” may be used herein to characterize one or more forms of computer readable media except for a transitory, propagating signal.

[0096] Before describing such embodiments in more detail, however, it is instructive to present example environments in which embodiments of the present disclosure may be implemented.Example Lithography System

[0097] Systems such as those described herein may render benefits in a wide range of applications and implementations. For the sake of having a specific non-limiting example to facilitate description, one such application is in semiconductor photolithography. FIG. 1 shows a lithography system 100 that includes a light source 110. As described more fully below, light source 110 produces a pulsed light beam 112 and directs it to a photolithography exposure apparatus or scanner 120 that patterns microelectronic features on a wafer 124. Wafer 124 is placed on a wafer table 126 constructed to hold wafer 124 and connected to a positioner 128 configured to accurately position wafer 124 in accordance with certain parameters.2023P00384W001 14

[0098] Pulsed light beam 112 may have a wavelength in the DUV range, for example, with a wavelength of 193 nanometers (nm) or 248 nm. Scanner 120 includes an optical arrangement 122 having, for example, one or more condenser lenses, a mask, and an objective arrangement. The mask is movable along one or more directions, such as along an optical axis of pulsed light beam 112 or in a plane that is perpendicular to the optical axis. The objective arrangement includes a projection lens and enables an image transfer to occur from the mask to photoresist on wafer 124. Light source 110 adjusts the range of angles for pulsed light beam 112 impinging on the mask.

[0099] Scanner 120 may include, among other features, a lithography controller 130 that controls how layers are printed on wafer 124. Scanner 120 also homogenizes (makes uniform) the intensity distribution of pulsed light beam 112 across the mask. Lithography controller 130 may include a memory that stores information such as process recipes that determine various parameters, including a duration of the exposure on wafer 124 based on, for example, the mask used, as well as other factors that affect exposure. During lithography, a burst of pulses of pulsed light beam 112 illuminates the same area of wafer 124 to constitute an illumination dose.

[0100] Lithography system 100 also preferably includes a control system 140. In general, control system 140 includes one or more of digital electronic circuitry, computer hardware, firmware, and software. Control system 140 may be centralized or be partially or wholly distributed throughout lithography system 100. In some embodiments, pulsed light beam 112 is implemented in a metrology / inspection system for use in a semiconductor manufacturing process.Example Light Source

[0101] FIG. 2 shows an example of a pulsed light source 210 that produces a pulsed laser beam. Pulsed light source 210 is an example of light source 110. FIG. 2 shows a two-chamber laser system (e.g., gas discharge laser system) as a non -limiting example but it will be understood that the principles explained herein are equally applicable to a single chamber laser system or a laser system having more than two chambers. Pulsed light source 210 may include, e.g., a solid state or gas discharge master oscillator (“MO”) seed laser system 220, relay optics 240, an amplification stage, e.g., a power ring amplifier (“PRA”) stage 250, and laser system output subsystem 270. MO seed laser system 220 may include, e.g., an MO chamber 230 that includes a pair of electrodes 232 and 234.

[0102] MO seed laser system 220 may also include a master oscillator output coupler (“MO OC”) 224, which may include a partially reflective mirror. MO seed laser system 220 may also include a line narrowing module (“LNM”) 222 that may include an optical grating. LNM 222 is adjustable to reflect a selected wavelength (or a narrow spectrum of light with a selected center wavelength) of light produced in MO chamber 230. LNM 222 and MO OC 224 are disposed around MO chamber 230 to form an oscillator cavity that oscillates to form a seed laser output pulse. MO seed laser system 220 may also include a line-center analysis module (“LAM”) 226. A MO wavefront engineering box (“WEB”) 242 of relay optics 240 may serve to adjust and redirect the output of MO seed laser system2023P00384W001 15220 toward PRA stage 250, and may include, e.g., a multi prism beam expander (not shown) and an optical delay path (not shown).

[0103] PRA stage 250 may include, e.g., a PRA chamber 260, which also may be an oscillator, e.g., formed by seed beam injection and output coupling optics (not shown) that may be incorporated into a PRA WEB 252. The beam may be redirected back through a gain medium in PRA chamber 260 by a beam reverser (“BR”) 254. PRA WEB 252 may incorporate a partially reflective input / output coupler (not shown) and a maximally reflective mirror for the nominal operating wavelength (e.g., at around 193 nm for an ArF system) and one or more prisms. PRA chamber 260 may include a pair of electrodes 262 and 264.

[0104] The laser output light beam of pulses then passes through PRA WEB 252 to a bandwidth analysis module (“BAM”) 272, an optical pulse stretcher (“OPuS”) 274, and an autoshutter, in this case a combined autoshutter metrology module (“CASMM”) 276, which may also be the location of a pulse energy meter. BAM 272 may receive the laser output light beam of pulses from PRA WEB 252 and pick off a portion of the light beam for metrology purposes, e.g., to measure the output bandwidth and pulse energy. One purpose of OPuS 274 may be, e.g., to convert a single output laser pulse into a pulse train. Secondary pulses created from the original single output pulse may be delayed with respect to each other. By distributing the original laser pulse energy into a train of secondary pulses, OPuS 274 may expand the effective pulse length of the laser and also reduce the peak pulse intensity. OPuS 274 may accordingly be arranged to receive the laser beam from BAM 272 and direct its output to CASMM 276.

[0105] PRA chamber 260 and MO chamber 230 may be configured as chambers that can hold a laser gas. In an excimer laser system, the laser gas can be, for example, a mixture of krypton and fluorine or a mixture of argon and fluorine, along with other components such as neon and xenon. Electrical pulses applied to electrode pairs 232 / 234 and 262 / 264 create gas discharges in the lasing gas. The gas discharges can cause the species of the lasing gas to combine into metastable combinations that rapidly decay and emit photons. A volume of gas discharge can serve as a laser gain medium. In an excimer laser, the excited combination in the gas discharge can be an excimer (excited dimer) or an exciplex (excited complex). An excimer is a short-lived homodimeric molecule formed from two species (e.g., Ar2, Kr2, F2, Xe2). An exciplex is a heterodimeric molecule formed from more than two species (e.g., ArF, KrCl, KrF, XeBr, XeCl, XeF). The light of the emitted photons is amplified as it propagates in the gas discharge, creating radiation that emerges through windows in chambers 230 and 260. The radiation can have a wavelength of, for example, 193 nm (from an ArF laser) or 248 nm (from a KrF laser), with a natural emission bandwidth of a few hundred picometers (pm). LNM 222 may be used to select a subset of wavelengths that are propagated in round trips through MO chamber 230. LNM 222 may thus be used to tune the center wavelength of the radiation and narrow the bandwidth of the radiation, for example to a bandwidth of approximately 0.8, 0.7, 0.6, 0.5, 0.4, or 0.3 pm.2023P00384W001 16

[0106] Alignment is the process of adjusting the position, orientation, etc. of these optical components so that the laser beam propagates along a desired beam path. Alignment of modules with respect to the laser beam and the other components may entail adjusting the components making up the module. For example, the alignment of the amplification stage may be determined with respect to a PRA alignment path 280 shown by the broken line in FIG. 2. PRA alignment path 280 as shown includes BR 254, PRA chamber 260, PRA WEB 252, BAM 272, OPuS 274, and CASMM 276. PRA alignment path 280 in the example shown also includes the path of the seed laser beam from MO WEB 242.

[0107] Alignment and other laser beam characteristics are determined by obtaining information about the laser beam at alignment ports at various positions in PRA alignment path 280, referred to herein as imaging the laser beam. For example, the laser beam may be imaged at a first position 290 at BR 254. The laser beam may also be imaged at a second position 292 at PRA WEB 252 and at a third position 294 at CASMM 276. These images may be near field images or far field images. Laser beam imaging may include obtaining information about the laser beam, laser beam edge detection, aperture edge detection, laser beam contours, laser beam cross sectional structure, positions of relay optics fixtures, and the like.Example Gas Discharge Chamber

[0108] FIG. 3 shows an example of a gas discharge chamber 300, according to various example embodiments. Gas discharge chamber 300 is an example of MO chamber 230 or PRA chamber 260 of pulsed light source 210. Gas discharge chamber 300 may be configured to excite a gas discharge medium 301 between a discharge gap 340 of an electrode assembly 360 (e.g., between a cathode assembly 320 and an anode assembly 330) and generate a light beam. Gas discharge chamber 300 may be further configured to measure (e.g., via a controller) one or more parameters of gas discharge chamber 300 (e.g., position of cathode, erosion rate of cathode, position of anode, erosion rate of anode, or a combination thereof) over time.

[0109] Although gas discharge chamber 300 is shown in FIG. 3 as a stand-alone apparatus and / or system, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1, 2, and 4-22, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 400, gas discharge chamber 400', gas discharge chamber 400", gas discharge chamber 400"', flow control assembly 440, flow control assembly 440', flow control assembly 440", preionization tube 470', flow diagram 900, gas discharge chamber 1000, actuator assembly 1040, actuator assembly 1040', actuator assembly 1040", electrode assembly 1160, flow diagram 1400, gas discharge chamber 1500, cathode assembly 1520, cathode assembly 1520', cathode assembly 1520", cathode assembly 1520'", cathode assembly 1520"", flow diagram 2000, electrode assembly 2160A, electrode assembly 2160B, electrode assembly 2160C, electrode assembly 2160D, computing system 2200, and / or any suitable metrology / inspection systems.

[0110] As shown in FIG. 3, gas discharge chamber 300 may include gas discharge medium 301, a chamber base 302, an interior surface 304, a cavity 308, a blower assembly 310, and electrode assembly2023P00384W001 17360. Chamber base 302 may include interior surface 304 forming cavity 308 to house gas discharge medium 301 (e.g., halogens, noble gases, and / or chemical compounds thereof), blower assembly 310, and electrode assembly 360. In some embodiments, chamber base 302 may include one or more rigid materials (e.g., metals, ceramics, etc.) to seal gas discharge medium 301 within cavity 308 of gas discharge chamber 300. In some embodiments, interior surface 304 may include one or more filters (e.g., screens, traps, etc.) configured to collect particles (e.g., metal fluoride dust) generated by electrode assembly 360. In some embodiments, gas discharge chamber 300 may be part of a light source, for example, a MO chamber and / or PRA chamber.[oni] In some embodiments, gas discharge chamber 300 may provide a feedback signal to a controller (e.g., via a feedback loop) to adjust a dimension (e.g., width) of discharge gap 340 over time (e.g., via an actuator 338) based on one or more measured parameters of gas discharge chamber 300. For example, gas discharge chamber 300 may measure an operating pressure of gas discharge medium 301 via one or more pressure sensors and provide the feedback signal to the controller. In some embodiments, gas discharge chamber 300 may provide a plurality of chamber operating pressures of gas discharge medium 301 over time to a controller coupled to gas discharge chamber 300 to determine a chamber operating pressure correlation (e.g., a trendline) to an electrode erosion rate (e.g., a cathode erosion rate) forthat gas discharge chamber 300.

[0112] In some embodiments, a controller may be configured to measure a chamber operating pressure of gas discharge medium 301 in gas discharge chamber 300. For example, the controller may measure chamber operating pressures of gas discharge chamber 300 over time and determine (e.g., calculate) a chamber operating pressure correlation (e.g., linear fit or polynomial fit of chamber operating pressures) to correlate the chamber pressure to an electrode erosion rate (e.g., a cathode erosion rate).

[0113] Gas discharge chamber 300 may include blower assembly 310. Blower assembly 310 may be configured to circulate gas discharge medium 301 within cavity 308. Blower assembly 310 may be further configured to flow gas discharge medium 301 (e.g., via a gas flow 314) through discharge gap 340. As shown in FIG. 3, blower assembly 310 may include a blower 312. Blower 312 may be configured to circulate gas discharge medium 301 (e.g., gas flow 314). In some embodiments, blower 312 may include a fan, a blower, an impeller, a rotor, a turbine, or any other rotary device that may circulate gas discharge medium 301. Blower 312 may be coupled (e.g., electrically) to a motor to control rotation of blower 312.

[0114] In some embodiments, blower assembly 310 may provide a feedback signal to a controller (e.g., via a feedback loop) to adjust a dimension (e.g., width) of discharge gap 340 overtime (e.g., via actuator 338) based on one or more measured parameters of blower assembly 310. For example, blower assembly 310 may measure a blower current signal of a motor coupled to blower 312 and provide the feedback signal to the controller. In some embodiments, blower assembly 310 may provide a plurality of blower current signals of a motor coupled to blower 312 over time to a controller coupled to blower2023P00384W001 18 assembly 310 to determine a blower current signal correlation (e.g., a trend) to an electrode erosion rate (e.g., a cathode erosion rate) for that gas discharge chamber 300.

[0115] In some embodiments, a controller may be configured to measure a blower current signal (e.g., motor current) of a motor coupled to blower assembly 310. For example, the controller may measure blower current signals (e.g., motor currents) of blower assembly 310 over time and determine (e.g., calculate) an average or trend to correlate the blower current to an electrode protrusion (e.g., a cathode protrusion, an anode protrusion, or both).

[0116] Gas discharge chamber 300 may include electrode assembly 360. Electrode assembly 360 may be configured to excite gas discharge medium 301 between discharge gap 340 of cathode assembly 320 and anode assembly 330 to generate a light beam. Electrode assembly 360 may be further configured to provide feedback to a controller (e.g., via a feedback loop) to adjust a dimension (e.g., width) of discharge gap 340 over time (e.g., via actuator 338) based on one or more measured parameters of electrode assembly 360. Electrode assembly 360 may be further configured to adjust one or more electrode positions (e.g., a position of first electrode 322 and / or a position of second electrode 332) over time (e.g., periodically) via adjustment of one or more actuators (e.g., actuator 338) to attain or maintain a desired discharge gap 340 (e.g., via a controller). As shown in FIG. 3, electrode assembly 360 may include cathode assembly 320 and anode assembly 330.

[0117] Cathode assembly 320 may be configured to act as a cathode (e.g., negative charge) and excite gas discharge medium 301 between discharge gap 340. As shown in FIG. 3, cathode assembly 320 may include a first electrode 322 (e.g., cathode (-)), one or a first plurality of capacitors 324, and one or a second plurality of capacitors 326. First electrode 322 may include a first discharge surface 344 configured to generate a discharge plasma and form a first endpoint of discharge gap 340. First electrode 322 may be coupled (e.g., electrically) to one or first plurality of capacitors 324 and one or second plurality of capacitors 326. First and second capacitors 324, 326 may be configured to supply a charge (e.g., high negative charge) to first electrode 322 and / or a second electrode 332 of anode assembly 330.

[0118] In some embodiments, electrode assembly 360 includes a resistor, inductor, and capacitor (RLC) circuit. In some embodiments, first and second capacitors 324, 326 may be peaking capacitors (Cp) configured to generate high-frequency pulses (e.g., nanosecond pulses). In some embodiments, first and second capacitors 324, 326 may be a single capacitor (e.g., a peaking capacitor) coupled to first electrode 322 and / or second electrode 332. In some embodiments, cathode assembly 320 may include a peaking circuit (e.g., a power supply, a peaking capacitor, and an electrode) to generate high- frequency peak currents. In some embodiments, cathode assembly 320 may include a pulsed power supply coupled to first electrode 322, first capacitor 324, and second capacitor 326.

[0119] In some embodiments, cathode assembly 320 may be stationary. In some embodiments, cathode assembly 320 may be adjustable such that a position of first electrode 322 (e.g., first discharge surface 344) relative to second electrode 332 (e.g., a second discharge surface 346) may be changed, thereby adjusting discharge gap 340. For example, cathode assembly 320 may include one or more actuators2023P00384W001 19(e.g., similar to actuator 338) coupled to first electrode 322 to adjust a position of first discharge surface 344 to attain or maintain a desired discharge gap 340. In some embodiments, cathode assembly 320 is opposite anode assembly 330, for example, perpendicular to anode assembly 330 such that first and second discharge surfaces 344, 346 are facing one another.

[0120] In some embodiments, electrode assembly 360 may provide a feedback signal to a controller (e.g., via a feedback loop) to adjust a dimension (e.g., width) of discharge gap 340 over time (e.g., via actuator 338) based on one or more measured parameters of electrode assembly 360 (e.g., cathode assembly 320). For example, electrode assembly 360 may measure a capacitor voltage waveform of first capacitors 324 and / or second capacitors 326 and provide the feedback signal to the controller. In some embodiments, cathode assembly 320 may provide a capacitor voltage waveform (e.g., voltage on capacitor) of first capacitors 324 and / or second capacitors 326 coupled to first electrode 322 to a controller coupled to cathode assembly 320 to determine a capacitor voltage waveform correlation (e.g., signature or shift) to an electrode erosion rate (e.g., a cathode erosion rate) for that gas discharge chamber 300.

[0121] In some embodiments, a controller may be configured to measure a capacitor voltage waveform (e.g., voltage on capacitor) of at least one of first capacitors 324 and / or second capacitors 326 coupled to first electrode 322. For example, the controller may measure capacitor voltage waveforms (e.g., voltage on capacitor) of cathode assembly 320 over time and determine (e.g., calculate) one or more changes in capacitor voltage waveforms to correlate the one or more changes in capacitor voltage waveforms to an electrode erosion rate (e.g., a cathode erosion rate).

[0122] Anode assembly 330 may be configured to act as an anode. As shown in FIG. 3, anode assembly 330 may include second electrode 332 (e.g., anode (+)) and one or more actuators 338 (e.g., linear motor, spring). Second electrode 332 may include second discharge surface 346 configured to generate a discharge plasma and form a second endpoint of discharge gap 340. In some embodiments, current return tines may be coupled (e.g., electrically) to second electrode 332 and may be configured to establish an electrical path from second electrode 332 to cathode assembly 320 (e.g., an RLC circuit, peaking capacitors, and / or a pulsed power supply). Actuator 338 may be configured to adjust a position (e.g., vertical position) of second discharge surface 346 to maintain discharge gap 340. In some embodiments, actuator 338 may include one or more actuators (e.g., linear motor, servo motor, piezoelectric, stepper, cam, spring, etc.).

[0123] In some embodiments, anode assembly 330 may be adjustable such that a position of second electrode 332 (e.g., second discharge surface 346) relative to first electrode 322 (e.g., first discharge surface 344) may be changed, thereby adjusting discharge gap 340. For example, anode assembly 330 may include one or more actuators (e.g., actuator 338) coupled to second electrode 332 to adjust a position of second discharge surface 346 to attain or maintain a desired discharge gap 340. In some embodiments, electrode assembly 360 may include a movable anode assembly (e.g., anode assembly 330) controlled by one or more actuators (e.g., actuator 338). For example, certain movable anode2023P00384W001 20 assemblies have been previously described in U.S. Patent No. 8,526,481, issued September 3, 2013, and U.S. Patent No. 11,777,271, issued October 3, 2023, which are hereby incorporated by reference herein in their entireties.Example Gas Discharge Chambers with Flow Control Assemblies

[0124] As discussed above, gas discharge chambers (e.g., MO chamber) have limited lifetime due to various performance issues (e.g., electrode erosion, gas mixture degradation, impurity accumulation, optical window damage, etc.), and replacement can be time-consuming and costly. In particular, electrode erosion can impose significant limits on the useful lifetime of a gas discharge chamber, and can lead to both an increase in the discharge gap and broadening of the generated discharge.

[0125] Currently, some systems utilize one or more movable electrodes to compensate for electrode erosion over time and attempt to control the discharge gap. However, some gas discharge chambers have slower or faster electrode erosion rates than others (e.g., variation of up to ±15%), and an average erosion rate may not be reliable as a metric. For example, different gas discharge chambers with nominally the same design can exhibit different erosion rates (e.g., due to the way the gas discharge chamber is being used). Also, some gas discharge chambers may use a stationary electrode (e.g., a stationary cathode), whose erosion over time can lead to turbulent or irregular flow (e.g., non-laminar) of the gas discharge medium in the discharge gap. Further, current systems may not actively measure an anode position and / or a cathode position over time and, thus, may not maintain appropriate flow in the discharge gap over time.

[0126] Embodiments of flow control apparatuses, systems, and methods as discussed below may actively maintain flow between the discharge gap (e.g., maintain laminar flow), actively maintain the discharge gap over time (e.g., periodically, in real-time, in near real-time), simultaneously adjust actuators associated with the anode and the cathode (e.g., based on a predetermined ratio), provide feedback to a controller (e.g., via a feedback loop and / or control signals) to adjust one or more actuators over time based on a measured parameter of the light source (e.g., a position of cathode, an erosion rate of cathode, a position of anode, an erosion rate of anode, or a combination thereof), reduce errors in the generated light beam, reduce errors in a lithographic process, perform diagnostics of the light source, identify optimal maintenance planning or adjustment of the light source, maintain laminar flow of the gas discharge medium in the discharge gap, and increase a lifetime of the light source.

[0127] FIGS. 4-8 illustrate example gas discharge chambers 400, 400', 400", 400"' with flow control assemblies 440, 440', 440", according to various example embodiments. In some embodiments, gas discharge chamber 300 may include two or more flow control assemblies 440, 440', 440" extending along a longitudinal direction (e.g., along +X axis) of first and second electrodes 322, 332.Example Gas Discharge Chamber with Translating Flow Control Assembly

[0128] FIGS. 4 and 5 illustrate a gas discharge chamber 400 with a flow control assembly 440, according to an example embodiment. Gas discharge chamber 400 is similar to gas discharge chamber 300 shown in FIG. 3 and similar reference numbers are used to indicate the similar features of gas2023P00384W001 21 discharge chamber 300 shown in FIG. 3 and gas discharge chamber 400 shown in FIGS. 4 and 5. A difference between the embodiments of gas discharge chamber 300 shown in FIG. 3 and the embodiments of gas discharge chamber 400 shown in FIGS. 4 and 5 is that gas discharge chamber 400 includes flow control assembly 440 for a cathode assembly 420, rather than just cathode assembly 320 of gas discharge chamber 300 shown in FIG. 3. Discussion of gas discharge chamber 400 components and / or functionality (e.g., cathode assembly 420, anode assembly 430, a discharge gap 412, a first discharge surface 414, a second discharge surface 416, etc.) is not duplicated here for brevity, but the embodiments and features of each are similar to gas discharge chamber 300 described above.

[0129] Flow control assembly 440 may be configured to move with (e.g., be flush to, be parallel with) a first discharge surface 414 (e.g., first discharge surface 344 (FIG. 3)) to maintain flow (e.g., laminar flow) of a gas discharge medium (e.g., gas discharge medium 301 (FIG. 3)) through a discharge gap 412 (e.g., discharge gap 340 (FIG. 3)). Flow control assembly 440 may be further configured to be adjacent a first electrode 422 and move with (e.g., be flush to, be parallel with) first discharge surface 414 of first electrode 422 over time (e.g., as first electrode 422 erodes over time) to maintain flow between flow control assembly 440 (e.g., an overhang 445) and first discharge surface 414. Flow control assembly 440 may be further configured to compensate for erosion of first electrode 422 overtime (e.g., for a number of laser pulses, for example, one billion pulses (1 Bp)), thereby increasing lifetime of a light source. Flow control assembly 440 may be further configured to simultaneously adjust a position of overhang 445 to move with first discharge surface 414 of first electrode 422 and adjust a position of a second discharge surface 416 of a second electrode 432 (e.g., second discharge surface 346 (FIG. 3)) to maintain discharge gap 412 (e.g., based on a predetermined ratio).

[0130] Although gas discharge chamber 400 with flow control assembly 440 is shown in FIGS. 4 and 5 as a stand-alone apparatus and / or system, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1-3 and 6-22, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, preionization tube 470', flow diagram 900, gas discharge chamber 1000, actuator assembly 1040, actuator assembly 1040', actuator assembly 1040", electrode assembly 1160, flow diagram 1400, gas discharge chamber 1500, cathode assembly 1520, cathode assembly 1520', cathode assembly 1520", cathode assembly 1520'", cathode assembly 1520"", flow diagram 2000, electrode assembly 2160A, electrode assembly 2160B, electrode assembly 2160C, electrode assembly 2160D, computing system 2200, and / or any suitable metrology / inspection systems.

[0131] As shown in FIG. 4, gas discharge chamber 400 may include a base 410, a cathode assembly 420, an anode assembly 430, flow control assembly 440, and preionization tube 470. Base 410 may be configured to provide an insulating (e.g., non-conductive) support for overhang 445 adjacent first electrode 422 (e.g., adjacent a first discharge surface). Base 410 may be coupled to flow control assembly 440 (e.g., overhang 445). In some embodiments, base 410 may include a ceramic insulator (e.g., clay, porous clay, glass, zirconia, alumina, steatite, cordierite, spinel, wollastonite, or a2023P00384W001 22 combination thereof) or any other rigid insulating (e.g., non-conductive) material. In some embodiments, base 410 may be stationary (e.g., coupled to a chamber base). In some embodiments, base 410 may be adjustable, for example, via one or more actuators coupled to base 410 (e.g., similar to actuator 338 (FIG. 3)).

[0132] As shown in FIGS. 4 and 5, flow control assembly 440 may include overhang 445. Overhang 445 may be configured to be adjustable and move with first electrode 422 (e.g., first discharge surface 344 (FIG. 3)) over time. Overhang 445 may be further configured to maintain flow (e.g., laminar flow) between the discharge gap (e.g., discharge gap 340 (FIG. 3)). In some embodiments, overhang 445 may include a ceramic insulator (e.g., clay, porous clay, glass, zirconia, alumina, steatite, cordierite, spinel, wollastonite, or a combination thereof) or any other rigid insulating (e.g., non-conductive) material. As shown in FIGS. 4 and 5, overhang 445 may include a fairing 446 (e.g., a distal tip). In some embodiments, fairing 446 may extend along a distal end of overhang 445 and be adjacent first electrode 422. Fairing 446 may be configured to be flush to or parallel with a first discharge surface of first electrode 422 and maintain flow between overhang 445 and the first discharge surface (e.g., first discharge surface 344 (FIG. 3)).

[0133] In some embodiments, a controller may be configured to adjust a position of overhang 445 (e.g., via flow control assembly 440) based on one or more measured parameters (e.g., a position of first electrode 422, an erosion rate of first electrode 422, a position of second electrode 432, an erosion rate of second electrode 432, or a combination thereof). For example, flow control assembly 440 may receive one or more control signals from a controller based on a measured parameter of first electrode 422 (e.g., a position of the first discharge surface, an erosion rate of the first discharge surface, or a combination thereof). In some embodiments, the controller may be configured to adjust a position of overhang 445 periodically overtime. In some embodiments, the controller may be configured to adjust a position of overhang 445 continuously over time. In some embodiments, the controller may be configured to adjust a position of overhang 445 automatically overtime, for example, via a closed-loop feedback algorithm that incorporates or has as its inputs one or more measured parameters of gas discharge chamber 400.

[0134] Flow control assembly 440 may be configured to adjust overhang 445 and optimize a position of overhang 445 relative to a first discharge surface of first electrode 422 (e.g., cathode protrusion from base 410). Flow control assembly 440 may be further configured to move overhang 445 with first electrode 422 overtime (e.g., as first electrode 422 erodes) to maintain smooth flow (e.g., laminar flow) between overhang 445 and first electrode 422, and maintain smooth flow (e.g., laminar flow) through the discharge gap. Flow control assembly 440 may be further configured to simultaneously adjust a position of overhang 445 and adjust a position of second electrode 432 (e.g., via actuator 338 of anode assembly 330 (FIG. 3)) to maintain the discharge gap. As shown in FIG. 4, flow control assembly 440 may include a first overhang actuator 442, a first spring 444, a second overhang actuator 447, a second spring 448, a motor 450, an actuator 452, a connector 454, and a support 455.2023P00384W001 23

[0135] First overhang actuator 442 may be configured to apply a force to overhang 445 to adjust a position of overhang 445 over time. As shown in FIGS. 4 and 5, first overhang actuator 442 may be coupled to first spring 444 and overhang 445. In some embodiments, first overhang actuator 442 may include a cam or a linear shape configured to transfer a restoring force of first spring 444 to overhang 445 (e.g., rotational motion, counter-clockwise (CCW)). In some embodiments, first overhang actuator 442 may include or be coupled to a motor or a force mechanism (e.g., first spring 444). In some embodiments, first overhang actuator 442 may include one or more linear motors, servo motors, piezoelectrics, steppers, cams, or any other suitable actuator capable of applying a force to overhang 445.

[0136] First spring 444 may be configured to apply a restoring force to first overhang actuator 442 thereby adjusting a position of overhang 445 over time. As shown in FIGS. 4 and 5, first spring 444 may be coupled to first overhang actuator 442. In some embodiments, first spring 444 may include or be coupled to a motor or a force mechanism (e.g., a dynamic spring, a spring actuator, a pneumatic spring, etc.). In some embodiments, first spring 444 may include one or more dynamic springs, spring actuators, pneumatic springs, tension adjustable springs, or any other suitable spring capable of applying a restoring force to first overhang actuator 442. In some embodiments, first spring 444 may be coupled (e.g., fixed) to a chamber base of gas discharge chamber 400 (e.g., chamber base 302 (FIG. 3)).

[0137] In some embodiments, flow control assembly 440 may include a plurality of actuators (e.g., first and second overhang actuators 442, 446 and first and second springs 444, 448, respectively) configured to adjust overhang 445 evenly along a longitudinal direction (e.g., +X axis) of first electrode 422. For example, as shown in FIG. 4 and 5, flow control assembly 440 may include first overhang actuator 442 coupled to first spring 444 and overhang 445 (e.g., at a first distal end) and second overhang actuator 446 coupled to second spring 448 and overhang 445 (e.g., at a second distal end opposite the first distal end). In some embodiments, fairing 446 of overhang 445 may extend along a longitudinal direction of base 410 and first electrode 422. For example, as shown in FIG. 5, fairing 446 may extend between first and second overhang actuators 442, 446 at first and second distal ends of overhang 445.

[0138] Motor 450 may be configured to generate a force (e.g., linear motion) along actuator 452. In some embodiments, motor 450 may be controlled by one or more control signals from a controller. As shown in FIG. 4, motor 450 may be coupled to actuator 452. In some embodiments, motor 450 may include one or more DC motors, AC motors, gear motors, linear motors, servo motors, piezoelectric motors, stepper motors, or any other suitable motor capable of applying a force to actuator 452.

[0139] Actuator 452 may be configured to apply a force to overhang 445 to adjust a position of overhang 445 over time . Actuator 452 may be further configured to adjust a position of second electrode 432 via an actuator of anode assembly 430 (e.g., force of actuator 452 transferred to actuator 338 (FIG. 3) via one or more couplings). As shown in FIG. 4, actuator 452 may be coupled to connector 454 and motor 450. In some embodiments, actuator 452 may include one or more rods, bars, arms, poles, cams, connectors, or any other suitable actuator capable of applying a force to overhang 445. In some2023P00384W001 24 embodiments, actuator 452 may include an elevator mechanism or a ratchet mechanism, for example, actuator 452 may include one or more toothed surfaces capable of providing an activated state and a released state (e.g., a linear ratchet, a piezo ratchet, etc.).

[0140] In some embodiments, motor 450 may move actuator 452 over time (e.g., based on a measured parameter) and thereby move overhang 445 to a desired position (e.g., flush to or parallel with the first discharge surface of first electrode 422). For example, as shown in FIG. 4, motor 450 may apply a first applied force 453 (e.g., linear motion, +Y axis) along actuator 452 to connector 454 coupled to actuator 452, a second applied force 456 (e.g., linear motion, +Y axis) along support 455 coupled to connector 454, and a third applied force 459 (e.g., rotational motion, CCW) to overhang 445 (e.g., via first overhang actuator 442) coupled to support 455, thereby moving overhang 445 accordingly (e.g., vertically aligned with the first discharge surface of first electrode 422).

[0141] Connector 454 may be configured to transfer motion from actuator 452 to support 455 (e.g., transfer first applied force 453 to second applied force 456). Connector 454 may be coupled to actuator 452 and support 455. In some embodiments, connector 454 may be part of actuator 452 or support 455.

[0142] Support 455 may be configured to transfer motion from connector 454 to overhang 445 (e.g., transfer second applied force 456 to third applied force 459). Support 455 may be further configured to adjust overhang 445 to be flush with the first discharge surface. Support 455 may be further configured to adjust a restoring force of first spring 444 by a predetermined amount (e.g., based on an angled surface). Support 455 may be further configured to apply a sloped surface (e.g., a predetermined angle) to overhang 445 (e.g., via first overhang actuator 442). Support 455 may be coupled to connector 454 and first overhang actuator 442. In some embodiments, support 455 may have a U-shape or double right-angle design to apply a linear force to first overhang actuator 442 and circumvent anode assembly 430 (e.g., extend around a perimeter of anode assembly 430). In some embodiments, support 455 may be positioned such that gas flow (e.g., gas flow 314 (FIG. 3)) between the discharge gap is not interrupted or affected by movement of support 455.

[0143] As shown in FIG. 4, support 455 may include a surface 458 configured to couple (e.g., mate) with first overhang actuator 442. In some embodiments, surface 458 may include an angled or sloped surface configured to mate with first overhang actuator 442 and transfer second applied force 456 (e.g., linear motion) from support 455 to third applied force 459 (e.g., rotational motion, clockwise (CW)) along first overhang actuator 442. For example, as shown in FIG. 4, surface 458 of support 455 may restrict first overhang actuator 442 from rotating (e.g., CCW) further, counter-balancing the restoring (spring) force of first spring 444, and as surface 458 of support 455 moves linearly (e.g., via second applied force 456) along first overhang actuator 442, the restoring force of first spring 444 may be released to rotate first overhang actuator 442 about a distal end of surface 458 of support 455 (e.g., via third applied force 459), thereby adjusting a position of overhang 445. In some embodiments, surface 458 of support 455 may adjust (e.g., restrict) restoring force of first spring 444 by a predetermined amount (e.g., based on an angle of surface 458). For example, the predetermined amount may be based2023P00384W001 25 on an erosion rate of first electrode 422 overtime, such that an angle of surface 458 (e.g., an acute angle relative to second applied force 456) may generate a position change of overhang 445 equivalent to one third of a movement of second electrode 432.

[0144] In some embodiments, the angle or slope of surface 458 may be a predetermined angle based on an erosion rate (e.g., an average erosion rate) of first electrode 422, second electrode 432, or both. In some embodiments, for example, the predetermined angle of surface 458 (e.g., an acute angle of less than 90°) may correlate to a ratio of 1:N (e.g., 1:2, 1:3, 1:4, 1:5, etc.) such that for every adjustment of second electrode 432 (e.g., position of the second discharge surface), overhang 445 is adjusted by one N (e.g., one third for a ratio of 1 :3) of the adjustment of second electrode 432 (e.g., position of overhang 445 flush to position of the first discharge surface of first electrode 422). In some embodiments, the angle of surface 458 may be in a range of about 5° to about 85°, for example, about 20°. In some embodiments, surface 458 may include spokes or teeth configured to mate with first overhang actuator 442.Example Gas Discharge Chamber with Preionization Tube Flow Control Assembly

[0145] FIG. 6 illustrates a gas discharge chamber 400' with flow control assembly 440 and a preionization tube 470', according to an example embodiment. Although gas discharge chamber 400' with preionization tube 470' is shown in FIG. 6 as a stand-alone apparatus and / or system, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1-5 and 7-22, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, flow diagram 900, gas discharge chamber 1000, actuator assembly 1040, actuator assembly 1040', actuator assembly 1040", electrode assembly 1160, flow diagram 1400, gas discharge chamber 1500, cathode assembly 1520, cathode assembly 1520', cathode assembly 1520", cathode assembly 1520'", cathode assembly 1520"", flow diagram 2000, electrode assembly 2160A, electrode assembly 2160B, electrode assembly 2160C, electrode assembly 2160D, computing system 2200, and / or any suitable metrology / inspection systems.

[0146] The embodiments of gas discharge chamber 400 shown in FIGS. 4 and 5, for example, and the embodiments of gas discharge chamber 400' shown in FIG. 6 may be similar. Similar reference numbers are used to indicate features of the embodiments of gas discharge chamber 400 shown in FIGS. 4 and 5 and the similar features of the embodiments of gas discharge chamber 400' shown in FIG. 6. A difference between the embodiments of gas discharge chamber 400 shown in FIGS. 4 and 5 and the embodiments of gas discharge chamber 400' shown in FIG. 6 is that gas discharge chamber 400' includes preionization tube 470' with a preionization tube surface 472 (e.g., teardrop shape), rather than gas discharge chamber 400 with preionization tube 470 (e.g., circular shape) as shown in FIGS. 4 and 5.

[0147] As shown in FIG. 6, gas discharge chamber 400' may include base 410, cathode assembly 420, anode assembly 430, flow control assembly 440, and preionization tube 470'. Gas discharge chamber2023P00384W001 26400' is similar to gas discharge chamber 400 shown in FIGS. 4 and 5 and similar reference numbers are used to indicate the similar features of gas discharge chamber 400 shown in FIGS. 4 and 5 and gas discharge chamber 400' shown in FIG. 6. Discussion of gas discharge chamber 400' components and / or functionality (e.g., base 410, flow control assembly 440, overhang 445, etc.) is not duplicated here for brevity, but the embodiments and features of each are similar to gas discharge chamber 400 described above.

[0148] Preionization tube 470' may be configured to preionize a gas in gas discharge chamber 400'. Preionization tube 470' may be further configured to move with (e.g., be flush to, be parallel with) the first discharge surface of first electrode 422 over time (e.g., as first electrode 422 erodes over time) to maintain flow between preionization tube 470' and the first discharge surface, and maintain flow through the discharge gap. As shown in FIG. 6, preionization tube 470' may include preionization tube surface 472 and a preionization tube actuator 474.

[0149] Preionization tube 470' may be configured to be adjustable and move with the first discharge surface of first electrode 422 over time. Preionization tube 470' may be further configured to maintain flow (e.g., laminar flow) between the discharge gap. In some embodiments, preionization tube 470' may include one or more preionization capacitors. As shown in FIG. 6, preionization tube 470' may include preionization tube surface 472. In some embodiments, preionization tube surface 472 may be adjacent the first discharge surface of first electrode 422. Preionization tube surface 472 may be configured to be flush to or parallel with the first discharge surface and maintain flow between preionization tube 470' and the first discharge surface. In some embodiments, preionization tube surface 472 may have a noncircular shape. For example, as shown in FIG. 6, preionization tube surface 472 may have a teardrop shape. In some embodiments, preionization tube surface 472 (e.g., teardrop shape) may be adjusted (e.g., rotated, positioned) relative to the first discharge surface of first electrode 422 to maintain flow between the discharge gap.

[0150] Preionization tube actuator 474 may be configured to apply a force to preionization tube 470' to adjust a position and / or a rotation angle of preionization tube surface 472 over time. Preionization tube actuator 474 may be further configured to adjust a position and / or a rotation angle of preionization tube surface 472, for example, based on one or more control signals from a controller. As shown in FIG. 6, preionization tube actuator 474 may be coupled to preionization tube 470'. In some embodiments, preionization tube actuator 474 may include or be coupled to a motor. In some embodiments, preionization tube actuator 474 may include one or more rotation motors, linear motors, servo motors, piezoelectrics, steppers, cams, rotors, torsion motor, torsion spring, torsion screw, or any other suitable actuator capable of applying a force to preionization tube 470'.Example Gas Discharge Chamber with Gear-Based Flow Control Assembly

[0151] FIG. 7 illustrates a gas discharge chamber 400" with a flow control assembly 440', according to an example embodiment. Although gas discharge chamber 400" with flow control assembly 440' is shown in FIG. 7 as a stand-alone apparatus and / or system, the embodiments of this disclosure may be2023P00384W001 27 used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1- 6 and 8-22, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, preionization tube 470', flow diagram 900, gas discharge chamber 1000, actuator assembly 1040, actuator assembly 1040', actuator assembly 1040", electrode assembly 1160, flow diagram 1400, gas discharge chamber 1500, cathode assembly 1520, cathode assembly 1520', cathode assembly 1520", cathode assembly 1520'", cathode assembly 1520"", flow diagram 2000, electrode assembly 2160A, electrode assembly 2160B, electrode assembly 2160C, electrode assembly 2160D, computing system 2200, and / or any suitable metrology / inspection systems.

[0152] The embodiments of gas discharge chamber 400 shown in FIGS. 4 and 5, for example, and the embodiments of gas discharge chamber 400" shown in FIG. 7 may be similar. Similar reference numbers are used to indicate features of the embodiments of gas discharge chamber 400 shown in FIGS. 4 and 5 and the similar features of the embodiments of gas discharge chamber 400" shown in FIG. 7. A difference between the embodiments of gas discharge chamber 400 shown in FIGS. 4 and 5 and the embodiments of gas discharge chamber 400" shown in FIG. 7 is that gas discharge chamber 400" includes a gear-based actuator (e.g., flow control assembly 440' with an actuator 452, a connector 454, an arm 455', and a gear 441), rather than gas discharge chamber 400 with a spring-based actuator (e.g., flow control assembly 440 with first and second overhang actuators 442, 446 and corresponding first and second springs 444, 448, respectively) as shown in FIGS. 4 and 5.

[0153] As shown in FIG. 7, gas discharge chamber 400" may include base 410, cathode assembly 420, anode assembly 430, flow control assembly 440', and preionization tube 470. Gas discharge chamber 400" is similar to gas discharge chamber 400 shown in FIGS. 4 and 5 and similar reference numbers are used to indicate the similar features of gas discharge chamber 400 shown in FIGS. 4 and 5 and gas discharge chamber 400" shown in FIG. 7. Discussion of gas discharge chamber 400" components and / or functionality (e.g., base 410, overhang 445, preionization tube 470, etc.) is not duplicated here for brevity, but the embodiments and features of each are similar to gas discharge chamber 400 described above.

[0154] Flow control assembly 440' may be configured to adjust overhang 445 and optimize a position of overhang 445 relative to a first discharge surface of first electrode 422 (e.g., cathode protrusion from base 410). Flow control assembly 440' may be further configured to move overhang 445 with first electrode 422 overtime (e.g., as first electrode 422 erodes) to maintain smooth flow (e.g., laminar flow) between overhang 445 and the first discharge surface, and maintain smooth flow (e.g., laminar flow) through the discharge gap. As shown in FIG. 7, flow control assembly 440' may include actuator 452, connector 454, arm 455', and gear 441.

[0155] Actuator 452 may be configured to apply a force to overhang 445 to adjust a position of overhang 445 over time. As shown in FIG. 7, actuator 452 may be coupled to connector 454. In some embodiments, actuator 452 may include or be coupled to a motor (e.g., motor 450 (FIG. 4)). In some embodiments, actuator 452 may include one or more linear motors, servo motors, piezoelectrics,2023P00384W001 28 steppers, cams, or any other suitable actuator capable of applying a force to overhang 445. In some embodiments, actuator 452 may include an elevator mechanism or a ratchet mechanism, for example, actuator 452 may include one or more toothed surfaces capable of providing an activated state and a released state (e.g., a linear ratchet, a piezo ratchet, etc.).

[0156] In some embodiments, actuator 452 may move overtime (e.g., based on a measured parameter) and thereby move overhang 445 to a desired position (e.g., flush to or parallel with the first discharge surface of first electrode 422). For example, as shown in FIG. 7, actuator 452 may apply a first applied force 453' (e.g., linear motion, -Y axis) along actuator 452 to connector 454 coupled to actuator 452, a second applied force 456' (e.g., linear motion, -Y axis) along arm 455' coupled to connector 454, a third applied force 443 (e.g., rotational motion, CW) to gear 441 coupled to arm 455', and a fourth applied force 459 (e.g., rotational motion, CCW) to overhang 445 coupled to gear 441, thereby moving overhang 445 accordingly (e.g., vertically aligned with the first discharge surface of first electrode 422).

[0157] Connector 454 may be configured to transfer motion from actuator 452 to arm 455' (e.g., transfer first applied force 453' to second applied force 456'). Connector 454 may be coupled to actuator 452 and arm 455'. Arm 455' may be configured to transfer motion from connector 454 to gear 441 (e.g., transfer second applied force 456' to third applied force 443). Arm 455' may be coupled to connector 454 and gear 441. In some embodiments, arm 455' may have an L-shape or right-angle design to apply a linear force to gear 441. In some embodiments, arm 455' may be positioned such that gas flow (e.g., gas flow 314 (FIG. 3)) through the discharge gap is not interrupted or affected by arm 455' movement. As shown in FIG. 7, arm 455' may include a surface 458' configured to couple (e.g., interlock) with gear 441. In some embodiments, surface 458' may include a toothed surface configured to interlock with gear 441 and transfer second applied force 456' (e.g., linear motion, -Y axis) from arm 455' to third applied force 443 (e.g., rotational motion, CW) along gear 441.

[0158] Gear 441 may be configured to transfer motion from arm 455' to overhang 445 (e.g., transfer third applied force 443 to fourth applied force 459). Gear 441 may be further configured to adjust overhang 445 to be flush with the first discharge surface (e.g., based on a gear ratio). Gear 441 may be further configured to apply a gear ratio (e.g., a predetermined ratio) to overhang 445. In some embodiments, the gear ratio may be a predetermined ratio based on an erosion rate (e.g., an average erosion rate) of first electrode 422, second electrode 432, or both. In some embodiments, for example, the predetermined ratio may be 1:N, where N is an integer greater than 1 (e.g., 1:2, 1:3, 1:4, 1:5, etc.), such that for every adjustment of second electrode 432 (e.g., position of the second discharge surface), overhang 445 is adjusted by one N (e.g., one third for a ratio of 1:3) of the adjustment of second electrode 432 (e.g., position of overhang 445 flush to position of the first discharge surface). In some embodiments, gear 441 may include spokes or teeth configured to interlock with surface 458' of arm 455' and a surface 449 of overhang 445.

[0159] As shown in FIG. 7, overhang 445 may include fairing 446 (e.g., a distal tip) and surface 449. Surface 449 may be configured to couple (e.g., interlock) with gear 441. In some embodiments, surface2023P00384W001 29449 may include a toothed surface configured to interlock with gear 441 and transfer third applied force 443 (e.g., rotational motion, CW) from gear 441 to fourth applied force 459 (e.g., rotational motion, CCW) along overhang 445, thereby adjusting overhang 445 vertically with the first discharge surface.

[0160] In some embodiments, flow control assembly 440' may be coupled to an actuator of anode assembly 430 (e.g., actuator 338 of anode assembly 330 (FIG. 3)). For example, arm 455' may be coupled to an actuator (e.g., actuator 338 (FIG. 3)). In some embodiments, a controller may be configured to adjust a position of overhang 445 (e.g., via flow control assembly 440') to maintain flow between overhang 445 and the first discharge surface of first electrode 422, and adjust a position of the second discharge surface of second electrode 432 (e.g., via actuator 338 (FIG. 3)) to maintain the discharge gap.Example Gas Discharge Chamber with Discrete Flow Control Assembly

[0161] FIG. 8 illustrates a gas discharge chamber 400'" with a flow control assembly 440", according to an example embodiment. Although gas discharge chamber 400'" with flow control assembly 440" is shown in FIG. 8 as a stand-alone apparatus and / or system, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1- 7 and 9-22, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, preionization tube 470', flow diagram 900, gas discharge chamber 1000, actuator assembly 1040, actuator assembly 1040', actuator assembly 1040", electrode assembly 1160, flow diagram 1400, gas discharge chamber 1500, cathode assembly 1520, cathode assembly 1520', cathode assembly 1520", cathode assembly 1520'", cathode assembly 1520"", flow diagram 2000, electrode assembly 2160A, electrode assembly 2160B, electrode assembly 2160C, electrode assembly 2160D, computing system 2200, and / or any suitable metrology / inspection systems.

[0162] The embodiments of gas discharge chamber 400 shown in FIGS. 4 and 5, for example, and the embodiments of gas discharge chamber 400'" shown in FIG. 8 may be similar. Similar reference numbers are used to indicate features of the embodiments of gas discharge chamber 400 shown in FIGS. 4 and 5 and the similar features of the embodiments of gas discharge chamber 400'" shown in FIG. 8. A difference between the embodiments of gas discharge chamber 400 shown in FIGS. 4 and 5 and the embodiments of gas discharge chamber 400'" shown in FIG. 8 is that gas discharge chamber 400'" includes a discrete actuator (e.g., flow control assembly 440" with a discrete actuator 461), rather than gas discharge chamber 400 with a spring-based actuator (e.g., flow control assembly 440 with first and second springs 444, 448) as shown in FIGS. 4 and 5.

[0163] As shown in FIG. 8, gas discharge chamber 400'" may include base 410, cathode assembly 420, anode assembly 430, flow control assembly 440", and preionization tube 470. Gas discharge chamber 400'" is similar to gas discharge chamber 400 shown in FIGS. 4 and 5 and similar reference numbers are used to indicate the similar features of gas discharge chamber 400 shown in FIGS. 4 and 5 and gas discharge chamber 400'" shown in FIG. 8. Discussion of gas discharge chamber 400'" components and / or functionality (e.g., base 410, overhang 445, preionization tube 470, etc.) is not duplicated here2023P00384W001 30 for brevity, but the embodiments and features of each are similar to gas discharge chamber 400 described above.

[0164] Flow control assembly 440" may be configured to adjust overhang 445 and optimize a position of overhang 445 relative to the first discharge surface of first electrode 422 (e.g., cathode protrusion from base 410). Flow control assembly 440" may be further configured to move overhang 445 with first electrode 422 overtime (e.g., as first electrode 422 erodes) to maintain smooth flow (e.g., laminar flow) between overhang 445 and the first discharge surface, and maintain smooth flow (e.g., laminar flow) through the discharge gap. As shown in FIG. 8, flow control assembly 440" may include discrete actuator 461.

[0165] Discrete actuator 461 may be configured to apply a force to overhang 445 to adjust a position of overhang 445 overtime. Discrete actuator 461 may be further configured to adjust a position and / or a rotation angle of overhang 445, for example, based on one or more control signals from a controller. As shown in FIG. 8, discrete actuator 461 may be coupled to overhang 445. In some embodiments, discrete actuator 461 may include or be coupled to a motor. In some embodiments, discrete actuator 461 may include one or more rotation motors, linear motors, servo motors, piezoelectrics, steppers, cams, rotors, torsion motor, torsion spring, torsion screw, or any other suitable actuator capable of applying a force to overhang 445. For example, as shown in FIG. 8, discrete actuator 461 may include a torsion spring 463 configured to rotate overhang 445 to a desired position (e.g., flush to or parallel with the first discharge surface of first electrode 422). In some embodiments, discrete actuator 461 may apply a first applied force 459 (e.g., rotational motion, CCW) to overhang 445, thereby moving fairing 446 or overhang 445 accordingly (e.g., vertically aligned with the first discharge surface of first electrode 422).Example Flow Diagram

[0166] FIG. 9 illustrates flow diagram 900 according to an example embodiment. For example, flow diagram 900 may be for pulsed light source 210 shown in FIG. 2. Flow diagram 900 may be configured to adjust a position of flow control assembly 400, 400', 400" (e.g., overhang 445) relative to a position of first electrode 422 (e.g., first discharge surface 344 (FIG. 3)). Flow diagram 900 may be configured to move flow control assembly 400, 400', 400" with (e.g., be flush to, be parallel with) the first discharge surface 344 to maintain flow (e.g., laminar flow) of gas discharge medium 301 through discharge gap 340. Flow diagram 900 may be further configured to compensate for erosion of first electrode 422 over time (e.g., for a number of laser pulses, for example, 1 Bp), thereby increasing lifetime of pulsed light source 210. Flow diagram 900 may be further configured to measure one or more parameters of pulsed light source 210 (e.g., a position of cathode, an erosion rate of cathode, a position of anode, an erosion rate of anode, or a combination thereof) and maintain flow between and / or adjust discharge gap 340 based on the one or more measured parameters.

[0167] It is to be appreciated that not all operations in FIG. 9 are needed to perform the disclosure provided herein. Further, some of the operations may be performed simultaneously, sequentially, and / or2023P00384W001 31 in a different order than shown in FIG. 9. Flow diagram 900 shall be described with reference to FIGS. 1-8 and 22. However, flow diagram 900 is not limited to those example embodiments.

[0168] Although flow diagram 900 is shown in FIG. 9 as a stand-alone method, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1-8, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, gas discharge chamber 400, gas discharge chamber 400', gas discharge chamber 400", gas discharge chamber 400"', flow control assembly 440, flow control assembly 440', flow control assembly 440", preionization tube 470', computing system 2200, and / or any suitable metrology / inspection systems. In some embodiments, flow diagram 900 may be implemented by pulsed light source 210 shown in FIG. 2 (e.g., via a controller). In some embodiments, flow diagram 900 may be implemented by gas discharge chamber 300 shown in FIG. 3 (e.g., via a controller).

[0169] In operation 902, as shown in the example of FIGS. 1-8, one or more parameters of a gas discharge chamber (e.g., gas discharge chamber 400 (FIG. 4)) of a light source (e.g., pulsed light source 210 (FIG. 2)) may be measured. In some embodiments, the parameter(s) may be measured periodically (e.g., a position of cathode, an erosion rate of cathode, a position of anode, an erosion rate of anode, or a combination thereof). In some embodiments, the parameter(s) may be measured in real-time or near real-time.

[0170] In operation 904, as shown in the example of FIGS. 1-8, a position of a flow control surface (e.g., overhang 445 (FIG. 4) and / or preionization tube 470' (FIG. 6)) adjacent a first electrode (e.g., first electrode 422 (FIG. 4)) may be adjusted, for example, based on the one or more measured parameter(s). In some embodiments, the position of overhang 445 and / or preionization tube 470' may be adjusted by adjusting one or more actuators (e.g., flow control assembly 440, flow control assembly 440', flow control assembly 440", preionization tube actuator 474, discrete actuator 461), for example, based on the one or more measured parameter(s) (e.g., an erosion rate of cathode). In some embodiments, adjusting the position of overhang 445 and / or the position of preionization tube 470' may reduce errors in a light source (e.g., pulsed light source 210 (FIG. 2)). In some embodiments, one or more actuators may adjust a position of overhang 445 such that overhang 445 is flush with the first discharge surface of first electrode 422 (e.g., first discharge surface 344 of first electrode 322 (FIG. 3)). In some embodiments, one or more actuators may adjust a position and / or an angle of preionization tube 470' such that preionization tube 470' (e.g., preionization tube surface 472) is flush with the first discharge surface of first electrode 422 (e.g., first discharge surface 344 of first electrode 322 (FIG. 3)). In some embodiments, one or more actuators may adjust the position of overhang 445 and / or the position of preionization tube 470' relative to the first discharge surface of first electrode 422 periodically or continuously over time.

[0171] In operation 906, as shown in the example of FIGS. 1-8, gas flow between the flow control surface (e.g., overhang 445 (FIG. 4) and / or preionization tube 470' (FIG. 6)) and the first electrode (e.g., first electrode 422 (FIG. 4)) may be maintained over time, for example, by one or more control signals2023P00384W001 32 from a controller (e.g., in a closed-loop feedback algorithm) based on the one or more measured parameter(s). In some embodiments, adjustment of the position of overhang 445 relative to (e.g., flush to, parallel with) the first discharge surface of first electrode 422 (e.g., first discharge surface 344 of first electrode 322 (FIG. 3)) may maintain laminar flow between overhang 445 and the first discharge surface, and maintain laminar flow through the discharge gap (e.g., discharge gap 340 (FIG. 3)). In some embodiments, gas flow between the discharge gap (e.g., discharge gap 340 (FIG. 3)) may be maintained overtime, for example, based on the one or more measured parameter(s).

[0172] In some embodiments, gas flow between preionization tube 470' and the first discharge surface of first electrode 422 (e.g., first discharge surface 344 of first electrode 322 (FIG. 3)) may be maintained over time, for example, by one or more control signals from a controller (e.g., in a closed-loop feedback algorithm) based on the one or more measured parameter(s). In some embodiments, adjustment of the position and / or the rotation angle of preionization tube 470' (e.g., preionization tube surface 472) relative to (e.g., flush to, parallel with) the first discharge surface of first electrode 422 (e.g., first discharge surface 344 of first electrode 322 (FIG. 3)) may maintain laminar flow between preionization tube 470' and the first discharge surface, and maintain laminar flow through the discharge gap (e.g., discharge gap 340 (FIG. 3)).

[0173] In operation 908, optionally, as shown in the example of FIGS. 1-8, an erosion rate of the first electrode (e.g., first electrode 422 (FIG. 3)) (a cathode erosion rate) may be measured, for example, based on an average or historical trend of the gas discharge chamber (e.g., gas discharge chamber 400 (FIG. 4)).

[0174] In operation 910, optionally, as shown in the example of FIGS. 1-8, the discharge gap (e.g., discharge gap 340 (FIG. 3)) may be maintained between the first and second electrodes (e.g., first and second electrodes 422, 432 (FIG. 4)) based on the measured parameter(s). In some embodiments, the discharge gap (e.g., discharge gap 340 (FIG. 3)) may be adjusted by adjusting a position of the second discharge surface (e.g., second discharge surface 346 (FIG. 3)) with an actuator (e.g., actuator 338 (FIG. 3)) coupled to the second electrode (e.g., second electrode 332 (FIG. 3)) based on the measured parameter(s). In some embodiments, the discharge gap (e.g., discharge gap 340 (FIG. 3)) may be adjusted by adjusting a position of the first discharge surface (e.g., first discharge surface 344 (FIG. 3)) with an actuator (e.g., similar to actuator 338 (FIG. 3)) coupled to the first electrode (e.g., first electrode 322 (FIG. 3)) based on the measured parameter(s).Example Gas Discharge Chamber with Actuator Assembly

[0175] As discussed above, gas discharge chambers (e.g., MO chamber) have limited lifetime due to various performance issues (e.g., electrode erosion, gas mixture degradation, impurity accumulation, optical window damage, etc.), and replacement can be time-consuming and costly. In particular, electrode erosion can impose significant limits on the useful lifetime of a gas discharge chamber, and can lead to both an increase in the discharge gap and broadening of the generated discharge . Over time, the electrodes can erode due to fast ions and electrons from the generated discharge during lasing. As2023P00384W001 33 the electrodes erode, the discharge gap can increase to the point where operational characteristics of the laser are so severely affected that laser operation must be stopped. Further, at higher pulse rates (e.g., kHz to MHz and above), electrode erosion can increase significantly and correspondingly decrease lifetime of the gas discharge chamber.

[0176] Currently, some systems utilize one or more movable electrodes to compensate for electrode erosion over time and attempt to control the discharge gap. However, some gas discharge chambers have slower or faster electrode erosion rates than others (e.g., variation of up to ±15%), and an average erosion rate may not be reliable as a metric. Also, current systems may not actively measure an electrode position (e.g., a cathode position) overtime and, thus, may not maintain an accurate discharge gap over time. Further, current systems may not be capable of simultaneous adjustment of both electrodes to maintain an accurate discharge gap over time.

[0177] Embodiments of light source apparatuses, systems, and methods as discussed below can compensate for electrode erosion over time and maintain a discharge gap over time. Advantageously, the system may actively maintain a discharge gap over time. Further advantageously, the system may actively maintain flow of a gas discharge medium between the discharge gap (e.g., maintain laminar flow). Further advantageously, the system may simultaneously adjust one or more actuators associated with an anode and a cathode (e.g., adjusting based on a predetermined ratio). Further advantageously, the system may provide feedback to a controller (e.g., via a feedback loop) to adjust one or more actuators over time based on one or more parameters of a light source (e.g., position of cathode, erosion rate of cathode, position of anode, erosion rate of anode, etc.). Further advantageously, the system may reduce errors in the generated light beam. Further advantageously, the system may reduce errors in a lithographic process. Further advantageously, the system may perform diagnostics of the light source. Further advantageously, the system may maintain laminar flow of a gas discharge medium in the discharge gap. Further advantageously, the system may allow for higher pulse repetition rates (e.g., faster than 1 kHz). Further advantageously, the system may increase lifetime of the light source.

[0178] FIGS. 10-13 illustrate a gas discharge chamber 1000 with an actuator assembly 1040, according to various example embodiments. Actuator assembly 1040 may be configured to actively maintain a discharge gap over time. Actuator assembly 1040 may be further configured to actively maintain flow of a gas discharge medium between the discharge gap (e.g., maintain laminar flow). Actuator assembly 1040 may be further configured to simultaneously adjust a position of an anode and a position of a cathode (e.g., based on a predetermined ratio). Actuator assembly 1040 may be further configured to allow for higher pulse repetition rates (e.g., faster than 1 kHz, in a range from 1 kHz to 1 MHz). Actuator assembly 1040 may be further configured to compensate for electrode erosion over time, thereby increasing lifetime of the light source.

[0179] Although gas discharge chamber 1000 is shown in FIGS. 10-13 as a stand-alone apparatus and / or system, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1-9, 13A, and 21A-22, e.g., lithography system2023P00384W001 34100, light source 110, pulsed light source 210, gas discharge chamber 300, gas discharge chamber 400, gas discharge chamber 400', gas discharge chamber 400", gas discharge chamber 400"', flow control assembly 440, flow control assembly 440', flow control assembly 440", preionization tube 470', flow diagram 900, actuator assembly 1040, actuator assembly 1040', actuator assembly 1040", electrode assembly 1160, flow diagram 1400, electrode assembly 2160A, electrode assembly 2160B, electrode assembly 2160C, electrode assembly 2160D, computing system 2200, and / or any suitable metrology / inspection systems.

[0180] The embodiments of gas discharge chamber 300 shown in FIG. 3, for example, and the embodiments of gas discharge chamber 1000 shown in FIGS. 10-13 may be similar. Similar reference numbers are used to indicate features of the embodiments of gas discharge chamber 300 shown in FIG. 3 and the similar features of the embodiments of gas discharge chamber 1000 shown in FIGS. 10-13. A difference between the embodiments of gas discharge chamber 300 shown in FIG. 3 and the embodiments of gas discharge chamber 1000 shown in FIGS. 10-13 is that gas discharge chamber 1000 includes actuator assembly 1040 coupled to a cathode assembly 1020, rather than gas discharge chamber 300 with actuator assembly 320 as shown in FIG. 3.

[0181] As shown in FIG. 10, gas discharge chamber 1000 may include a base 1010, cathode assembly 1020, an anode assembly 1030, actuator assembly 1040, and a preionization tube 1070. Gas discharge chamber 1000 is similar to gas discharge chamber 300 shown in FIG. 3 and similar reference numbers are used to indicate the similar features of gas discharge chamber 300 shown in FIG. 3 and gas discharge chamber 1000 shown in FIGS. 10-13. Discussion of gas discharge chamber 1000 components and / or functionality (e.g., cathode assembly 1020, anode assembly 1030, an electrode assembly 1060, etc.) is not duplicated here for brevity, but the embodiments and features of each are similar to gas discharge chamber 300 described above.

[0182] Gas discharge chamber 1000 may include base 1010. Base 1010 may be configured to provide an insulating (e.g., non-conductive) support for cathode assembly 1020 and preionization tube 1070. Base 1010 may be coupled to cathode assembly 1020. In some embodiments, base 1010 may include a ceramic insulator (e.g., clay, porous clay, glass, zirconia, alumina, steatite, cordierite, spinel, wollastonite, or a combination thereof) or any other rigid insulating (e.g., non-conductive) material. In some embodiments, base 1010 may be stationary (e.g., coupled to chamber base 302 (FIG. 3)). In some embodiments, base 1010 may be adjustable, for example, via one or more actuators coupled to base 1010 (e.g., similar to actuator 338 (FIG. 3)).

[0183] Gas discharge chamber 1000 may include preionization tube 1070. Preionization tube 1070 may be configured to preionize a gas in gas discharge chamber 1000 (e.g., gas discharge medium 301 (FIG. 3)).

[0184] Gas discharge chamber 1000 may include cathode assembly 1020. Cathode assembly 1020 may be configured to adjust a position of a first discharge surface 1014 of a first electrode 1022 relative to a second discharge surface 1016 of a second electrode 1032 of anode assembly 1030 to maintain a2023P00384W001 35 discharge gap 1012 (e.g., discharge gap 340 (FIG. 3)). As shown in FIGS. 10 and 11, cathode assembly 1020 may be coupled to actuator assembly 1040 (e.g., via a support 1042 and a coupling 1044). Cathode assembly 1020 may be part of electrode assembly 1060. Cathode assembly 1020 may be similar to cathode assembly 320 (FIG. 3). As shown in FIGS. 11 and 12, cathode assembly 1020 may include a cover 1024, an electrode support 1026, and an elevator mechanism 1028.

[0185] Cover 1024 may be configured to act as an insulating (e.g., non -conductive) flow guide for first electrode 1022. In some embodiments, cover 1024 may surround one or more sides of first electrode 1022 and extend along a longitudinal direction of first electrode 1022. In some embodiments, cover 1024 may include an insulating shell to provide an interior space or gap between an exterior surface of cathode assembly 1020 and first electrode 1022, such that first electrode 1022 may protrude (e.g., move outward) toward cover 1024 overtime and be flush with an exterior surface of cover 1024 and maintain the discharge gap.

[0186] Electrode support 1026 may be configured to support first electrode 1022 and allow first electrode 1022 to protrude outwardly away from electrode support 1026. Electrode support 1026 may be further configured to provide an insulating (e.g., non-conductive) support for first electrode 1022. In some embodiments, electrode support 1026 may be coupled to base 1010 (e.g., via a track, a rail, etc.). In some embodiments, electrode support 1026 may be coupled to actuator assembly 1040. For example, as shown in FIG. 11, electrode support 1026 may be coupled (e.g., secured) to coupling 1044 of actuator assembly 1040 via one or more connectors, for example, via a latch 1046. In some embodiments, a portion of electrode support 1026 may be configured to move along with actuator assembly 1040. For example, as shown in FIG. 11, electrode support 1026 may move along a direction of coupling 1044 of actuator assembly 1040 (e.g., along a direction of a third applied force 1047, -X axis).

[0187] In some embodiments, electrode support 1026 may be coupled to first electrode 1022, for example, via one or more transducers. In some embodiments, the one or more transducers may include one or more teeth or grooves to couple (e.g., interlock) first electrode 1022 to electrode support 1026. In some embodiments, the one or more transducers may include one or more actuators (e.g., linear motor, servo motor, piezoelectric, stepper, cam, spring, etc.). For example, as shown in FIGS. 11 and 12, springs 1029 may be attached between first electrode 1022 and electrode support 1026 to couple electrode support 1026 to first electrode 1022. In some embodiments, the one or more transducers may be configured to pre-load electrode support 1026 to move in a particular direction. For example, as shown in FIGS. 11 and 12, springs 1029 between first electrode 1022 and electrode support 1026 may be configured to apply a force (e.g., pre-loaded force) between first electrode 1022 and electrode support 1026 such that first electrode 1022 moves relative to electrode support 1026 in a predetermined direction. In some embodiments, electrode support 1026 may be part of elevator mechanism 1028.

[0188] Elevator mechanism 1028 may be configured to apply an outward (vertical) force (e.g., a fourth applied force 1023) to first electrode 1022. Elevator mechanism 1028 may be further configured to adjust a position of first electrode 1022 (e.g., protrusion of first electrode 1022) relative to second2023P00384W001 36 electrode 1032 based on an applied force from actuator assembly 1040. Elevator mechanism 1028 may be further configured to transfer or convert a first force (e.g., a third applied force 1047) from actuator assembly 1040 into a second force (e.g., fourth applied force 1023) to first electrode 1022, for example, converting an outward (horizontal) force from actuator assembly 1040 into an outward (vertical) force on first electrode 1022. In some embodiments, elevator mechanism 1028 may be formed from an interface between first electrode 1022 and electrode support 1026. For example, as shown in FIGS. 11 and 12, elevator mechanism 1028 may be formed from one or more teeth on a bottom surface of first electrode 1022 and one or more corresponding grooves on a top surface of electrode support 1026, thereby providing a positive slope or gradient for first electrode 1022 to travel outward (e.g., along fourth applied force 1023) as electrode support 1026 translates in a longitudinal direction of first electrode 1022 (e.g., along third applied force 1047). In some embodiments, elevator mechanism 1028 may include one or more toothed surfaces capable of providing an activated state and a released state (e.g., a linear ratchet, a piezo ratchet, etc.).

[0189] In some embodiments, elevator mechanism 1028 may be pre-loaded, for example, by one or more transducers (e.g., springs). For example, as shown in FIGS. 11 and 12, elevator mechanism 1028 may include one or more springs 1029 connected between first electrode 1022 and electrode support 1026 along a longitudinal direction of cathode assembly 1020. In some embodiments, elevator mechanism 1028 may be pre-loaded (e.g., under tension to apply an internal force) such that motion of electrode support 1026 in a first direction is transferred to motion of first electrode 1022 in a second direction, for example, in a second direction that is orthogonal (e.g., perpendicular) to the first direction. For example, as shown in FIGS. 11 and 12, elevator mechanism 1028 may be pre-loaded via springs 1029 such that horizontal motion of electrode support 1026 in a direction of coupling 1044 of actuator assembly 1040 (e.g., along a direction of third applied force 1047) is transferred into vertical motion of first electrode 1022 (e.g., along a direction of fourth applied force 1023) via elevator mechanism 1028, thereby causing first electrode 1022 to protrude outward (e.g., along +Z axis). In some embodiments, elevator mechanism 1028 may be magnetically pre-loaded to apply an outward force to first electrode 1022. For example, elevator mechanism 1028 may include one or more magnets (e.g., permanent magnets, electromagnets, etc.), for example, arranged along electrode support 1026 such that horizontal motion of electrode support 1026 in a direction of coupling 1044 is transferred into vertical motion of first electrode 1022.

[0190] Gas discharge chamber 1000 may include anode assembly 1030. Anode assembly 1030 may be configured to adjust a position of second electrode 1032 relative to first electrode 1022 of cathode assembly 1020 to maintain a discharge gap (e.g., discharge gap 340 (FIG. 3)). As shown in FIGS. 10 and 11, anode assembly 1030 may be coupled to actuator assembly 1040 (e.g., via a connector 1054). Anode assembly 1030 may be part of electrode assembly 1060. Anode assembly 1030 may be similar to anode assembly 330 (FIG. 3).2023P00384W001 37

[0191] Gas discharge chamber 1000 may include actuator assembly 1040. Actuator assembly 1040 may be configured to adjust a position of first electrode 1022 of cathode assembly 1020. Actuator assembly 1040 may be configured to adjust a position of second electrode 1032 of anode assembly 1030. Actuator assembly 1040 may be configured to actively maintain a discharge gap over time (e.g., via a controller). Actuator assembly 1040 may be further configured to actively maintain flow of a gas discharge medium between the discharge gap (e.g., maintain laminar flow). Actuator assembly 1040 may be further configured to simultaneously adjust a position of first electrode 1022 and a position of second electrode 1032 (e.g., based on a predetermined ratio). Actuator assembly 1040 may be further configured to allow for higher pulse repetition rates (e.g., faster than 1 kHz). Actuator assembly 1040 may be further configured to compensate for electrode erosion of first electrode 1022 and / or second electrode 1032 overtime thereby increasing lifetime of gas discharge chamber 1000. As shown in FIGS. 10 and 11, actuator assembly 1040 may include a support 1042, a coupling 1044, a motor 1050, an actuator 1052, and connector 1054.

[0192] Actuator assembly 1040 may include support 1042. Support 1042 may be configured to apply a force to coupling 1044 to adjust a position of first electrode 1022 over time. Support 1042 may be further configured to release a force from coupling 1044 (e.g., pre-loaded force) to adjust a position of first electrode 1022 overtime. As shown in FIGS. 10 and 11, support 1042 may be coupled to actuator 1052 (e.g., at a first distal end) and may be coupled to coupling 1044 (e.g., at a second distal end). In some embodiments, support 1042 may include an arm or bracket configured to transfer a force of actuator 1052 to coupling 1044. For example, as shown in FIGS. 10 and 11, support 1042 may transfer a first applied force 1053 (e.g., linear motion, +Y axis) from actuator 1052 into a second applied force 1043 (e.g., linear motion, +Y axis) to coupling 1044. In some embodiments, support 1042 may release an outward force (e.g., along -X axis) from coupling 1044 as a force is applied to support 1042 (e.g., along +Y axis). For example, as shown in FIG. 11, support 1042 may release third applied force 1047 (e.g., pre-loaded force) of coupling 1044 as second applied force 1043 is applied to support 1042. In some embodiments, support 1042 may act as a brake or restraint to hold back third applied force 1047 (e.g., pre-loaded force) along coupling 1044 and maintain a position of first electrode 1022.

[0193] In some embodiments, support 1042 may be coupled to coupling 1044 along a surface or interface between support 1042 and coupling 1044. For example, as shown in FIGS. 10 and 11, support1042 may be coupled to coupling 1044 along a surface 1045. Surface 1045 may be configured to move coupling 1044 a first distance relative to movement of support 1042 a second distance according to a predetermined ratio (e.g., first distance: second distance). In some embodiments, surface 1045 may include an angled or sloped surface configured to mate with support 1042 and coupling 1044, and transfer third applied force 1047 (e.g., pre-loaded force) from coupling 1044 to second applied force1043 along support 1042.

[0194] In some embodiments, surface 1045 may adjust (e.g., restrict) an outward force of coupling1044 (e.g., third applied force 1047) by a predetermined amount (e.g., based on an angle of surface2023P00384W001 381045). For example, as shown in FIG. 11, the predetermined amount may be based on an opening angle 1045a of surface 1045 (e.g., an acute angle relative to third applied force 1047). In some embodiments, an opening angle 1045a of surface 1045 may generate a position change of first electrode 1022. For example, the predetermined amount may be based on an erosion rate of first electrode 1022 over time, such that opening angle 1045a of surface 1045 may generate a position change of first electrode 1022 equivalent to one third of a movement of second electrode 1032.

[0195] In some embodiments, opening angle 1045a of surface 1045 may be a predetermined angle based on an erosion rate (e.g., an average erosion rate) of first electrode 1022, second electrode 1032, or both. For example, opening angle 1045a of surface 1045 (e.g., an acute angle of less than 90°) may correlate to a ratio of 1:N (e.g., 1:2, 1:3, 1:4, 1:5, etc.) such that for every adjustment of second electrode 1032 (e.g., via actuator assembly 1040), first electrode 1022 is adjusted by one N (e.g., one third for a ratio of 1:3) of the adjustment of second electrode 1032. In some embodiments, opening angle 1045a of surface 1045 may be in a range of about 5° to about 85°, for example, about 20°. In some embodiments, surface 1045 may include spokes or teeth configured to mate or interlock support 1042 and coupling 1044 to one another.

[0196] Actuator assembly 1040 may include coupling 1044. Coupling 1044 may be configured to apply a force to cathode assembly 1020 to adjust a position of first electrode 1022 overtime. Coupling 1044 may be further configured to release a force from cathode assembly 1020 (e.g., pre-loaded force) to adjust a position of first electrode 1022 over time. As shown in FIG. 11, coupling 1044 may be coupled to support 1042 (e.g., along surface 1045) and may be coupled to cathode assembly 1020, for example, via a connector (e.g., latch 1046). In some embodiments, coupling 1044 may be coupled to electrode support 1026 by one or more connectors. For example, as shown in FIG. 11, the one or more connectors may include latch 1046 configured to secure a distal end of coupling 1044 to electrode support 1026 and transfer any force of electrode support 1026 (e.g., pre-loaded force) along coupling 1044.

[0197] In some embodiments, coupling 1044 may include an arm or bracket configured to transfer a force (e.g., pre-loaded force) of cathode assembly 1020 (e.g., via electrode support 1026) to coupling 1044. For example, as shown in FIG. 11, coupling 1044 may transfer a pre-loaded force from cathode assembly 1020 (e.g., formed via springs 1029 of elevator mechanism 1028) into third applied force 1047 (e.g., linear motion) toward support 1042. In some embodiments, coupling 1044 may release an outward force (e.g., along -X axis) from cathode assembly 1020 such that an outward (vertical) force is applied to first electrode 1022 (e.g., along +Z axis). For example, as shown in FIG. 11, coupling 1044 may release third applied force 1047 (e.g., pre-loaded force) of cathode assembly 1020 (e.g., due to elevator mechanism 1028) thereby applying fourth applied force 1023 to first electrode 1022.

[0198] Actuator assembly 1040 may include motor 1050. Motor 1050 may be configured to generate a force (e.g., linear motion) along actuator 1052. In some embodiments, motor 1050 may be controlled2023P00384W001 39 by one or more control signals from a controller. As shown in FIG. 10, motor 1050 may be coupled to actuator 1052. In some embodiments, motor 1050 may be coupled to support 1042. In some embodiments, motor 1050 may be coupled to connector 1054. In some embodiments, motor 1050 may include one or more DC motors, AC motors, gear motors, linear motors, servo motors, piezoelectric motors, stepper motors, or any other suitable motor capable of applying a force to actuator 1052.

[0199] Actuator assembly 1040 may include actuator 1052. Actuator 1052 may be configured to apply a force to support 1042 to adjust a position of first electrode 1022 over time. Actuator 1052 may be further configured to apply a force to connector 1054 to adjust a position of second electrode 1032 over time. In some embodiments, actuator 1052 may be further configured to adjust a position of second electrode 1032 via actuator 338 (FIG. 3) (e.g., force of actuator 1052 transferred to actuator 338 of anode assembly 330 via one or more couplings). Actuator 1052 may be further configured to simultaneously adjust a position of first electrode 1022 and a position of second electrode 1032 over time, for example, according to a predetermined ratio (e.g., 1:3).

[0200] As shown in FIG. 10, actuator 1052 may be coupled to support 1042, connector 1054, and motor 1050. In some embodiments, actuator 1052 may include one or more rods, bars, arms, poles, cams, connectors, or any other suitable actuator capable of applying a force to cathode assembly 1020. In some embodiments, actuator 1052 may include an elevator mechanism or a ratchet mechanism. For example, actuator 1052 may include one or more toothed surfaces capable of providing an activated state and a released state (e.g., a linear ratchet, a piezo ratchet, etc.).

[0201] In some embodiments, motor 1050 may move actuator 1052 over time (e.g., based on a parameter) and thereby move first electrode 1022, in conjunction with elevator mechanism 1028, coupling 1044, and support 1042, to a desired position (e.g., to maintain discharge gap). For example, as shown in FIGS. 10 and 11, motor 1050 may apply first applied force 1053 (e.g., linear motion, +Y axis) along actuator 1052 to support 1042 coupled to actuator 1052 and second applied force 1043 (e.g., linear motion, +Y axis) along support 1042 coupled to coupling 1044, thereby releasing third applied force 1047 (pre-loaded) (e.g., outward horizontal motion, -X axis) along coupling 1044 and applying fourth applied force 1023 (protrusion) (e.g., outward vertical motion, +Z axis) via elevator mechanism 1028 to first electrode 1022, thereby moving first electrode 1022 accordingly.

[0202] Actuator assembly 1040 may include connector 1054. Connector 1054 may be configured to transfer motion from actuator 1052 to anode assembly 1030 (e.g., transfer first applied force 1053 to actuator 338 (FIG. 3)). Connector 1054 may be further configured to adjust a position of second electrode 1032 over time. Connector 1054 may be coupled to actuator 1052. In some embodiments, connector 1054 may be part of actuator 1052 or support 1042. In some embodiments, connector 1054 may be further configured to adjust a position of second electrode 1032 via actuator 338 (FIG. 3) (e.g., force of connector 1054 transferred to actuator 338 of anode assembly 330 via one or more couplings). Example Actuator Assembly with Rotational Coupling2023P00384W001 40

[0203] FIG. 12 illustrates gas discharge chamber 1000 with an actuator assembly 1040', according to an example embodiment. Although actuator assembly 1040' is shown in FIG. 12 as a stand-alone apparatus and / or system, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1-11, 13, 13A, and 21A-22, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, gas discharge chamber 400, gas discharge chamber 400', gas discharge chamber 400", gas discharge chamber 400'", flow control assembly 440, flow control assembly 440', flow control assembly 440", preionization tube 470', flow diagram 900, gas discharge chamber 1000, electrode assembly 1160, flow diagram 1400, electrode assembly 2160A, electrode assembly 2160B, electrode assembly 2160C, electrode assembly 2160D, computing system 2200, and / or any suitable metrology / inspection systems.

[0204] The embodiments of actuator assembly 1040 shown in FIGS. 10 and 11, for example, and the embodiments of actuator assembly 1040' shown in FIG. 12 may be similar. Similar reference numbers are used to indicate features of the embodiments of actuator assembly 1040 shown in FIGS. 10 and 11 and the similar features of the embodiments of actuator assembly 1040' shown in FIG. 12. A difference between the embodiments of actuator assembly 1040 shown in FIGS. 10 and 11 and the embodiments of actuator assembly 1040' shown in FIG. 12 is that actuator assembly 1040' includes a rotational coupling 1048 coupled to a tapered coupling 1044' and a support 1042', rather than actuator assembly 1040 with surface 1045 coupled to coupling 1044 and support 1042 as shown in FIGS. 10 and 11.

[0205] As shown in FIG. 12, actuator assembly 1040' may include support 1042', rotational coupling 1048, and tapered coupling 1044'. Actuator assembly 1040' is similar to actuator assembly 1040 shown in FIGS. 10 and 11 and similar reference numbers are used to indicate the similar features of actuator assembly 1040 shown in FIGS. 10 and 11 and actuator assembly 1040' shown in FIG. 12. Discussion of actuator assembly 1040' components and / or functionality (e.g., cathode assembly 1020, elevator mechanism 1028, springs 1029, motor 1050, actuator 1052, connector 1054, etc.) is not duplicated here for brevity, but the embodiments and features of each are similar to actuator assembly 1040 described above.

[0206] Actuator assembly 1040' may include support 1042'. Support 1042' may be configured to apply a first force to rotational coupling 1048, which is configured to apply a second force to tapered coupling 1044' to adjust a position of first electrode 1022 over time. Support 1042' and rotational coupling 1048 may be further configured to release a force from tapered coupling 1044' (e.g., pre-loaded force) to adjust a position of first electrode 1022 overtime. In some embodiments, support 1042' may include an arm or bracket configured to transfer a force of actuator 1052 to tapered coupling 1044' via rotational coupling 1048. For example, as shown in FIG. 12, rotational coupling 1048 may transfer second applied force 1043 (e.g., linear motion) from support 1042' into a fifth applied force 1051 (e.g., rotational motion) that is transferred to tapered coupling 1044'.

[0207] In some embodiments, support 1042' may release an outward force (e.g., along -X axis) from tapered coupling 1044' to rotational coupling 1048, which transfers the outward force into a rotational2023P00384W001 41 force (e.g., about +Z axis), and rotational coupling 1048 transfers the rotational force into an outward force (e.g., along +Y axis) to support 1042'. For example, as shown in FIG. 12, support 1042' may release third applied force 1047 (e.g., pre-loaded force) of tapered coupling 1044' via fifth applied force 1051 (e.g., rotational force) of rotational coupling 1048, which applies second applied force 1043 to support 1042'. In some embodiments, support 1042' may act as a brake or restraint to hold back third applied force 1047 (e.g., pre-loaded force) along tapered coupling 1044' and fifth applied force 1051 (e.g., rotational force) via rotational coupling 1048, and maintain a position of first electrode 1022.

[0208] Actuator assembly 1040' may include rotational coupling 1048. Rotational coupling 1048 may be disposed between support 1042' and tapered coupling 1044'. Rotational coupling 1048 may be configured to transfer a force between support 1042' and tapered coupling 1044'. As shown in FIG. 12, rotational coupling 1048 may be coupled to support 1042' (e.g., at a first distal end) and may be coupled to tapered coupling 1044' (e.g., at a second distal end). In some embodiments, rotational coupling 1048 may include a connector configured to receive a distal end of tapered coupling 1044'. For example, as shown in FIG. 12, rotational coupling 1048 may include a connector 1045' (e.g., a conical recess) configured to mate with a conical end 1044b of tapered coupling 1044'. In some embodiments, rotational coupling 1048 may include a pivot connection 1049 coupled to base 1010 and configured to transfer third applied force 1047 (e.g., linear motion) from tapered coupling 1044' to fifth applied force 1051 (e.g., rotational motion), and transfer fifth applied force 1051 (e.g., rotational motion) to second applied force 1043 (e.g., linear motion).

[0209] In some embodiments, rotational coupling 1048 may be configured to move tapered coupling 1044' a first distance relative to movement of support 1042' a second distance according to a predetermined ratio (e.g., first distance: second distance). In some embodiments, rotational coupling 1048 may include one or more connectors configured to mate with support 1042' and tapered coupling 1044' to transfer third applied force 1047 (e.g., pre-loaded force) from tapered coupling 1044' to second applied force 1043 along support 1042'. For example, as shown in FIG. 12, rotational coupling 1048 may be fixed (e.g., bolted, secured) to a distal end of support 1042'. For example, as shown in FIG. 12, rotational coupling may include connector 1045' (e.g., a conical recess) configured to mate with conical end 1044b of tapered coupling 1044'.

[0210] Actuator assembly 1040' may include tapered coupling 1044'. Tapered coupling 1044' may be configured to apply a force to cathode assembly 1020 to adjust a position of first electrode 1022 over time. Tapered coupling 1044' may be further configured to release a force from cathode assembly 1020 (e.g., pre-loaded force) to adjust a position of first electrode 1022 over time. As shown in FIG. 12, tapered coupling 1044' may be indirectly coupled to support 1042' via rotational coupling 1048 and may be coupled to cathode assembly 1020, for example, via a connector 1046' (e.g., a conical recess). In some embodiments, tapered coupling 1044' may be coupled to electrode support 1026 by one or more connectors. For example, as shown in FIG. 12, the one or more connectors may include connector 1046' (e.g., a conical recess) configured to secure a conical end 1044a of tapered coupling 1044' to electrode2023P00384W001 42 support 1026 and transfer any force of electrode support 1026 (e.g., pre-loaded force) along tapered coupling 1044'. In some embodiments, tapered coupling 1044' may be coupled to rotational coupling 1048 by one or more connectors. For example, as shown in FIG. 12, the one or more connectors may include connector 1045' (e.g., a conical recess) configured to secure a conical end 1044b of tapered coupling 1044' to rotational coupling 1048 and transfer any force of tapered coupling 1044' (e.g., pre- loaded force) along rotational coupling 1048.

[0211] In some embodiments, tapered coupling 1044' may include an arm or bracket configured to transfer a force (e.g., pre-loaded force) of cathode assembly 1020 (e.g., via electrode support 1026) to tapered coupling 1044'. For example, as shown in FIG. 12, tapered coupling 1044' may transfer a pre- loaded force from cathode assembly 1020 (e.g., formed via springs 1029 of elevator mechanism 1028) into third applied force 1047 (e.g., linear motion) to rotational coupling 1048 that transfers the force toward support 1042. In some embodiments, tapered coupling 1044' may release an outward force (e.g., along -X axis) from cathode assembly 1020 such that an outward (vertical) force is applied to first electrode 1022 (e.g., along +Z axis). For example, as shown in FIG. 12, tapered coupling 1044' may release third applied force 1047 (e.g., pre-loaded force) of cathode assembly 1020 (e.g., due to elevator mechanism 1028) thereby applying fourth applied force 1023 to first electrode 1022.Example Actuator Assembly with Conductive Flexure

[0212] FIG. 13 illustrates gas discharge chamber 1000 with an actuator assembly 1040", according to an example embodiment. Although actuator assembly 1040" is partially shown in FIG. 13 as a standalone apparatus and / or system, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1-12, 13A, and 21A-22, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, gas discharge chamber 400, gas discharge chamber 400', gas discharge chamber 400", gas discharge chamber 400'", flow control assembly 440, flow control assembly 440', flow control assembly 440", preionization tube 470', flow diagram 900, gas discharge chamber 1000, electrode assembly 1160, flow diagram 1400, electrode assembly 2160A, electrode assembly 2160B, electrode assembly 2160C, electrode assembly 2160D, computing system 2200, and / or any suitable metrology / inspection systems.

[0213] The embodiments of actuator assembly 1040 shown in FIGS. 10 and 11, the embodiments of actuator assembly 1040' shown in FIG. 12, and the embodiments of actuator assembly 1040" shown in FIG. 13 may be similar. Similar reference numbers are used to indicate features of the embodiments of actuator assembly 1040 and / or assembly 1040' shown in FIGS. 10-12 and the similar features of the embodiments of actuator assembly 1040" shown in FIG. 13. In some embodiments, a difference between the embodiments of actuator assembly 1040 and / or actuator assembly 1040' shown in FIGS. 10-12 and the embodiments of actuator assembly 1040" shown in FIG. 13 is that gas discharge chamber 1000 includes a conductive flexure 1100 and a first electrode 1022" moves along +Z direction (e.g., the movement is orthogonal to a top surface of first electrode 1022" or a top surface of an electrode support 1026"). Discussion of actuator assembly 1040" components and / or functionality (e.g., cathode assembly2023P00384W001 431020", first electrode 1022", electrode support 1026", elevator mechanism 1028", springs 1029", etc.) is not duplicated here for brevity, but the embodiments and features of each are similar to actuator assembly 1040 and / or actuator assembly 1040' described above.

[0214] Conductive flexure 1100 is configured to ensure a stable voltage supplied to first electrode 1022". In some embodiments, conductive flexure 1100 includes an elastic feature to dynamically adjust a movement of first electrode 1022". Further features and example embodiments of conductive flexure 1100, as well as its associated structure and operation of various embodiments, are described in detail below in an electrode assembly 1160 illustrated in FIG. 13 A.

[0215] Actuator assembly 1040" includes a support (not shown). The support may be configured to apply a force indirectly to adjust a position of first electrode 1022" over time. The support may be coupled to one or more components to increase or release a force to adjust a position of first electrode 1022" overtime. In some embodiments, the support (e.g., a support 1042" similar to support 1042 (FIG. 11)) transfers a third applied force 1047" to release an outward force (e.g., along -X axis) or increase an inward force (e.g., along +X axis) to apply a fourth applied force 1023" to adjust a position of first electrode 1022" and maintain a gap dimension between a pair of electrodes (e.g., first and second electrodes 1022, 1032) in gas discharge chamber 1000. In some embodiments, springs 1029" are attached between first electrode 1022" and electrode support 1026" to couple electrode support 1026" to first electrode 1022". Springs 1029" between first electrode 1022" and electrode support 1026" are configured to apply a force (e.g., pre-loaded force) between first electrode 1022" and electrode support 1026" such that first electrode 1022" moves relative to electrode support 1026" in a predetermined direction. In some embodiments, first electrode 1022" moves relative to electrode support 1026" along +Z axis (e.g., vertically). In some embodiments, electrode support 1026" may be part of elevator mechanism 1028".

[0216] FIG. 13A illustrates a cross-sectional view of electrode assembly 1160 along a line AA' as shown in FIG. 13, according to some example embodiments. Electrode assembly 1160 includes a conductive flexure 1100. Although electrode assembly 1160 is shown in FIG. 13A as a stand-alone apparatus and / or system, the embodiments of this disclosure can be used with other apparatuses, systems, and / or methods, such as, but not limited to, each electrode assembly and its associated components in FIGS. 1-13 and 21A-22, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, gas discharge chamber 400, gas discharge chamber 400', gas discharge chamber 400", gas discharge chamber 400'", flow control assembly 440, flow control assembly 440', flow control assembly 440", preionization tube 470', flow diagram 900, gas discharge chamber 1000, actuator assembly 1040, actuator assembly 1040', actuator assembly 1040", flow diagram 1400, electrode assembly 2160A, electrode assembly 2160B, electrode assembly 2160C, electrode assembly 2160D, computing system 2200, and / or any suitable metrology / inspection systems. The embodiments of electrode assembly 1160 shown in FIGS. 13 and 13A and, for example, and the2023P00384W001 44 embodiments of electrode assembly 360 shown in FIG. 3 and electrode assembly 1060 shown in FIGS. 10 and 11 may be similar.

[0217] As shown in FIG. 13 A, electrode assembly 1160 includes conductive flexure 1100, an electrode 1122, an electrode support 1126, and an elevator mechanism 1128. Conductive flexure 1100 includes a first portion 1102 electrically coupled to electrode 1122, a second portion 1104 electrically coupled to first portion 1102, a third portion 1106 electrically coupled to second portion 1104, and a fourth portion 1108 electrically coupled to both third portion 1106 and electrode support 1126. As shown in FIG. 13A, first portion 1102 extends along the Y-axis and aligns with an interface between electrode 1122 and elevator mechanism 1128. Second portion 1104 is oriented at an angle relative to the Z-axis and is coupled to third portion 1106, which is vertical or substantially vertical with respect to fourth portion 1108. Fourth portion 1108 extends along the Y-axis and towards elevator mechanism 1128, aligning with an interface between elevator mechanism 1128 and electrode support 1126. In at least one embodiment, first portion 1102, second portion 1104, third portion 1106, and fourth portion 1108 are integrated into one component.

[0218] Conductive flexure 1100 extends along a length of electrode 1122 and elevator mechanism 1128 (along the X-axis). In one embodiment, to protect elevator mechanism 1128 from being contaminated during the discharge chamber operation, a length of conductive flexure 1100 is equal to or greater than that of elevator mechanism 1128. In some embodiments, the length of conductive flexure 1100 is equal to or shorter than that of electrode 1122. To maintain continuous electrical connection between electrode 1122 and electrode support 1126 as electrode 1122 moves along with elevator mechanism 1128 in the Z-axis, conductive flexure 1100 functions as a dynamic electrical contact that accommodates this axial displacement to ensure a stable high voltage supply during the discharge chamber operation. First portion 1102 is in direct contact with electrode 1122, and fourth portion 1108 is in direct contact with electrode support 1126.

[0219] In one embodiment, second portion 1104 includes a series of folds 1110 that function as an elastic cushion. Folds 1110 dynamically extend or contract in response to the movement of electrode 1122 and / or elevator mechanism 1128, ensuring consistent electrical connectivity between electrode 1122 and electrode support 1126. Optionally, third portion 1106 may also include a second series of folds (not shown) to achieve a similar function of folds 1110. In some embodiments, conductive flexure 1100 includes a suitable material that exhibits both malleability and electrical conductivity, for example, such as copper, copper alloy (e.g., brasses, bronzes, copper-nickel alloys, tellurium copper), silver, gold, aluminum, or a combination thereof.

[0220] In some embodiments, a thickness T of conductive flexure 1100 ranges from about 0.2 millimeters (mm) to about 1 mm. In some embodiments, when thickness T is greater than 1 mm, in some cases, a resistance to deformation of the metal increases, which reduces the elasticity of conductive flexure 1100. In some embodiments, when thickness T is smaller than 0.2 mm, in some2023P00384W001 45 cases, an electricity conductivity of conductive flexure 1100 decreases and a risk of metal fracture increases.

[0221] In one embodiment, electrode 1122 functions as a cathode. In another embodiment, electrode 1122 functions as an anode. In terms of arrangement, in some embodiments, electrode 1122 is positioned above the other electrode in the gas discharge chamber. In other embodiments, electrode 1122 is positioned below and aligned with another electrode in the gas discharge chamber. Conductive flexure 1100 can be applied to the various embodiments detailed in FIGS. 3-13. Non-limiting examples include the coupling of conductive flexure 1100 to first electrode 1022 in FIGS. 11 and 12 and / or first electrode 1022" in FIG. 13, and the coupling of conductive flexure 1100 to second electrode 1032 in FIG. 11.Example Flow Diagram

[0222] FIG. 14 illustrates flow diagram 1400, according to an example embodiment. For example, flow diagram 1400 may be for pulsed light source 210 shown in FIG. 2. For example, flow diagram 1400 may be for gas discharge chamber 300 shown in FIG. 3. For example, flow diagram 1400 may be for gas discharge chamber 1000 shown in FIGS. 10-13. Flow diagram 1400 may be configured to determine one or more parameters of a light source (e.g., a position of first electrode 1022, an erosion rate of first electrode 1022, a position of second electrode 1032, an erosion rate of second electrode 1032, a chamber operating pressure, a blower current signal, a capacitor voltage waveform, or a combination thereof). Flow diagram 1400 may be further configured to adjust a discharge gap of electrode assembly 1060 based on the one or more parameters. Flow diagram 1400 may be further configured to maintain a discharge gap with one or more control signals from a controller based on the one or more parameters. Flow diagram 1400 may be further configured to reduce errors in a generated light beam, reduce errors in a lithographic process, perform diagnostics of a light source, and increase lifetime of the light source (e.g., pulsed light source 210 (FIG. 2)).

[0223] It is to be appreciated that not all steps in FIG. 14 are needed to perform the disclosure provided herein. Further, some of the steps may be performed simultaneously, sequentially, and / or in a different order than shown in FIG. 14. Flow diagram 1400 shall be described with reference to FIGS. 1-13A and 22. However, flow diagram 1400 is not limited to those example embodiments.

[0224] Although flow diagram 1400 is shown in FIG. 14 as a stand-alone method, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1-13A and 21A-22, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, gas discharge chamber 400, gas discharge chamber 400', gas discharge chamber 400", gas discharge chamber 400"', flow control assembly 440, flow control assembly 440', flow control assembly 440", preionization tube 470', flow diagram 900, gas discharge chamber 1000, actuator assembly 1040, actuator assembly 1040', actuator assembly 1040", electrode assembly 1160, electrode assembly 2160A, electrode assembly 2160B, electrode assembly 2160C, electrode assembly 2160D, computing system 2200, and / or any suitable metrology / inspection systems.2023P00384W001 46In some embodiments, flow diagram 1400 may be implemented by pulsed light source 210 shown in FIG. 2 (e.g., via a controller or control system 140). In some embodiments, flow diagram 1400 may be implemented by gas discharge chamber 300 shown in FIG. 3 (e.g., via a controller or control system 140). In some embodiments, flow diagram 1400 may be implemented by gas discharge chamber 1000 shown in FIGS. 10-13 (e.g., via a controller or control system 140).

[0225] In operation 1402, as shown in the example of FIGS. 1-13 A and 22, one or more parameters of a light source may be determined (e.g., measured). In some embodiments, the parameter(s) may be measured periodically (e.g., a position of first electrode 1022, an erosion rate of first electrode 1022, a position of second electrode 1032, an erosion rate of second electrode 1032, a chamber operating pressure, a blower current signal, a capacitor voltage waveform, or a combination thereof), for example, by one or more sensors or predetermined trends (e.g., an average). In some embodiments, the parameter(s) may be measured in real-time or near real-time.

[0226] In some embodiments, the parameter(s) may include a position of first electrode 1022, for example, relative to second electrode 1032 (e.g., along +Z axis). For example, as shown in FIG. 11, a position of first electrode 1022 may be measured relative to an exterior surface of cathode assembly 1020 (e.g., cover 1024) based on a force applied by actuator assembly 1040 (e.g., via support 1042). In some embodiments, the parameter(s) may include an erosion rate of first electrode 1022. For example, the erosion rate of first electrode 1022 may be measured or correlated to one or more control signals of the light source (e.g., a chamber operating pressure, a blower current signal, a capacitor voltage waveform, or a combination thereof). In some embodiments, for example, the erosion rate of first electrode 1022 may be predetermined based on a measured average rate for one or more similar gas discharge chambers. In some embodiments, for example, the erosion rate of first electrode 1022 may be determined or correlated to a pulse repetition rate (e.g., 4 kHz, 8 kHz, 16 kHz, etc.) and / or a number of pulses of the gas discharge chamber.

[0227] In some embodiments, the parameter(s) may include a position of second electrode 1032, for example, relative to first electrode 1022 (e.g., along -Z axis). For example, as shown in FIG. 11, a position of second electrode 1032 may be measured relative to an exterior surface of anode assembly 1030 (e.g., a cover) based on a force applied by actuator assembly 1040 (e.g., via connector 1054). In some embodiments, the parameter(s) may include an erosion rate of second electrode 1032. For example, the erosion rate of second electrode 1032 may be measured or correlated to one or more control signals of the light source (e.g., a chamber operating pressure, a blower current signal, a capacitor voltage waveform, or a combination thereof). In some embodiments, for example, the erosion rate of second electrode 1032 may be predetermined based on a measured average rate for one or more similar gas discharge chambers. In some embodiments, for example, the erosion rate of second electrode 1032 may be determined or correlated to a pulse repetition rate (e.g., 4 kHz, 8 kHz, 16 kHz, etc.) and / or a number of pulses of the gas discharge chamber.2023P00384W001 47

[0228] In some embodiments, the parameter(s) may include a chamber operating pressure of gas discharge chamber 1000. For example, chamber operating pressures may be measured over time (e.g., via one or more pressure sensors). In some embodiments, the parameter(s) may include a chamber operating pressure correlation to an electrode erosion rate (e.g., a cathode erosion rate). For example, a chamber operating pressure correlation may be determined for that gas discharge chamber 1000 (e.g., a linear fit or a polynomial fit of chamber operating pressures) to correlate the chamber pressure to an electrode erosion rate (e.g., a cathode erosion rate).

[0229] In some embodiments, the parameter(s) may include a blower current signal of a motor coupled to blower assembly 310. For example, one or more blower current signals may be measured over time (e.g., via a controller). In some embodiments, the parameter(s) may include a change in the blower current signal over time.

[0230] In some embodiments, the parameter(s) may include a capacitor voltage waveform of one or first plurality of capacitors 324 and / or one or second plurality of capacitors 326 coupled to first electrode 322. For example, capacitor voltage waveforms may be measured overtime (e.g., via a controller).

[0231] In operation 1404, as shown in the example of FIGS. 1-13A and 22, a discharge gap (e.g., discharge gap 340 (FIG. 3)) between first and second electrodes 1022, 1032 may be adjusted (e.g., via actuator assembly 1040 to adjust a position of first electrode 1022 and / or a position of second electrode 1032) based on the one or more parameter(s). In some embodiments, the discharge gap may be adjusted by adjusting a position of first electrode 1022 via actuator assembly 1040 (e.g., via actuator 1052, support 1042, coupling 1044, and elevator mechanism 1028) based on the one or more parameter(s). In some embodiments, the discharge gap may be adjusted by adjusting a position of second electrode 1032 via actuator assembly 1040 (e.g., via actuator 1052, connector 1054, and actuator 338 (FIG. 3)) based on the one or more parameter(s). In some embodiments, the discharge gap may be adjusted by simultaneously adjusting a position of first electrode 1022 and a position of second electrode 1032 via actuator assembly 1040.

[0232] In operation 1406, as shown in the example of FIGS. 1-13A and 22, the discharge gap (e.g., discharge gap 340 (FIG. 3)) may be maintained by one or more control signals from a controller (e.g., in a closed-loop feedback algorithm) based on the one or more parameter(s).

[0233] In some embodiments, the one or more control signals may be based on a chamber operating pressure of a gas discharge medium of gas discharge chamber 1000 (e.g., via one or more pressure sensors coupled to the controller). In some embodiments, the one or more control signals may be based on a blower current signal of a motor coupled to a blower assembly of gas discharge chamber 1000 (e.g., via the controller). In some embodiments, the one or more control signals may be based on a capacitor voltage waveform of one or first plurality of capacitors and / or one or second plurality of capacitors coupled to first electrode 1022 of electrode assembly 1060 (e.g., via a controller).

[0234] In some embodiments, the one or more control signals may be based on direct imaging of the discharge gap. For example, one or more light detectors may directly image and measure the discharge2023P00384W001 48 gap over time. In some embodiments, the controller may correlate a change in the image to a change in the discharge gap.

[0235] In some embodiments, the one or more control signals may be based on voltage feedback of the electrode assembly. For example, the one or more control signals may be based on a change in the interelectrode voltage (e.g., voltage across discharge gap). In some embodiments, the controller may correlate a change in the interelectrode voltage to a change in the discharge gap.

[0236] In some embodiments, the one or more control signals may be based on correlated velocity measurements (e.g., flow speed) of a gas discharge medium of gas discharge chamber 1000 (e.g., via one or more pitot tube sensors coupled to the controller). For example, gas discharge chamber 1000 may include one or more pitot tubes placed downstream of the discharge gap that can measure a change in turbulence or flow separation of the gas discharge medium. In some embodiments, the controller may correlate a change in turbulence or flow separation of the gas discharge medium (e.g., via one or more pitot tubes) to a change in the discharge gap.

[0237] In operation 1408, optionally, as shown in the example of FIGS. 1-13A and 22, a chamber operating pressure of a gas discharge medium of gas discharge chamber 1000 may be measured (e.g., via one or more pressure sensors coupled to a controller).

[0238] In operation 1410, optionally, as shown in the example of FIGS. 1-13A and 22, a blower current signal of a motor coupled to a blower assembly of gas discharge chamber 1000 may be measured (e.g., via a controller).

[0239] In operation 1412, optionally, as shown in the example of FIGS. 1-13 A and 22, a capacitor voltage waveform of one or first plurality of capacitors and / or one or second plurality of capacitors coupled to first electrode 1022 of electrode assembly 1060 may be measured (e.g., via a controller).

[0240] In some embodiments, a sequence of operation 1408, operation 1410, and operation 1412 may be performed in an opposite or alternative order, depending on processing efficiency. For example, the blower current signal and / or the capacitor voltage waveform may be used to perform a coarse adjustment, and the chamber operating pressure may be used to provide fine-tuning of the discharge gap-Example Cathode Assembly with Translational Rod

[0241] As discussed above, gas discharge chambers (e.g., MO chamber) have limited lifetime due to various performance issues (e.g., electrode erosion, gas mixture degradation, impurity accumulation, optical window damage, etc.), and replacement can be time-consuming and costly. In particular, electrode erosion can impose significant limits on the useful lifetime of a gas discharge chamber, and can lead to both an increase in the discharge gap and broadening of the generated discharge. As the electrodes erode, the discharge gap can increase to the point where operational characteristics of the laser are so severely affected that laser operation must be stopped. Further, at higher pulse rates (e.g., kHz to MHz and above), electrode erosion can increase significantly and correspondingly decrease lifetime of the gas discharge chamber.2023P00384W001 49

[0242] Currently, some systems utilize one or more movable electrodes to compensate for electrode erosion over time and attempt to control the discharge gap. However, some gas discharge chambers have slower or faster electrode erosion rates than others (e.g., variation of up to ±15%), and an average erosion rate may not be reliable as a metric. Also, some gas discharge chambers may use a stationary electrode (e.g., a stationary cathode), whose erosion over time can lead to an increase in the discharge gap. Further, current systems may not actively measure an electrode position (e.g., a cathode position) over time and, thus, may not maintain an accurate discharge gap over time. Additionally, current systems may not be capable of simultaneous adjustment of both electrodes to maintain an accurate discharge gap over time.

[0243] Embodiments of light source apparatuses, systems, and methods as discussed below can compensate for electrode erosion over time and maintain a discharge gap over time. Advantageously, the system may actively maintain a discharge gap over time. Further advantageously, the system may reduce errors in the generated light beam. Further advantageously, the system may reduce errors in a lithographic process. Further advantageously, the system may increase lifetime of the light source.

[0244] FIG. 15 illustrates a gas discharge chamber 1500 with a cathode assembly 1520, according to various example embodiments. Cathode assembly 1520 may be configured to actively maintain a discharge gap over time. Cathode assembly 1520 may be further configured to adjust a position of a first discharge surface to thereby maintain the discharge gap over time. Cathode assembly 1520 may be further configured to compensate for electrode erosion overtime, thereby increasing lifetime of the light source.

[0245] Although gas discharge chamber 1500 is shown in FIG. 15 as a stand-alone apparatus and / or system, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1-3 and 16-20, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, cathode assembly 1520, cathode assembly 1520', cathode assembly 1520", cathode assembly 1520"', cathode assembly 1520"", flow diagram 2000, and / or any suitable metrology / inspection systems.

[0246] The embodiments of gas discharge chamber 300 shown in FIG. 3, for example, and the embodiments of gas discharge chamber 1500 shown in FIG. 15 may be similar. Similar reference numbers are used to indicate features of the embodiments of gas discharge chamber 300 shown in FIG. 3 and the similar features of the embodiments of gas discharge chamber 1500 shown in FIG. 15. A difference between the embodiments of gas discharge chamber 300 shown in FIG. 3 and the embodiments of gas discharge chamber 1500 shown in FIG. 15 is that gas discharge chamber 1500 includes cathode assembly 1520 with a rod 1580 extending through a bolt 1522 and a first electrode 1528 (e.g., a cathode) and a tip portion 1590 coupled to rod 1580 to adjust a position of a first discharge surface 1592, rather than gas discharge chamber 300 with actuator assembly 320 as shown in FIG. 3.

[0247] As shown in FIG. 15, gas discharge chamber 1500 may include a base 1510, cathode assembly 1520, and a preionization tube 1570. Gas discharge chamber 1500 is similar to gas discharge chamber2023P00384W001 50300 shown in FIG. 3 and similar reference numbers are used to indicate the similar features of gas discharge chamber 300 shown in FIG. 3 and gas discharge chamber 1500 shown in FIG. 15. Discussion of gas discharge chamber 1500 components and / or functionality (e.g., an anode assembly 1530 (not shown), a discharge gap 1540 (not shown), an electrode assembly 1560, etc.) is not duplicated here for brevity, but the embodiments and features of each are similar to gas discharge chamber 300 described above.

[0248] Gas discharge chamber 1500 may include base 1510. Base 1510 may be configured to provide an insulating (e.g., non-conductive) support for cathode assembly 1520 and preionization tube 1570. Base 1510 may be coupled to cathode assembly 1520. In some embodiments, base 1510 may include a ceramic insulator (e.g., clay, porous clay, glass, zirconia, alumina, steatite, cordierite, spinel, wollastonite, or a combination thereof) or any other rigid insulating (e.g., non-conductive) material. In some embodiments, base 1510 may be stationary (e.g., coupled to chamber base 302 (FIG. 3)).

[0249] Gas discharge chamber 1500 may include preionization tube 1570. Preionization tube 1570 may be configured to preionize a gas in gas discharge chamber 1500 (e.g., gas discharge medium 301 (FIG. 3)).

[0250] Gas discharge chamber 1500 may include cathode assembly 1520. Cathode assembly 1520 may be configured to adjust a position of a first electrode 1528 (e.g., a tip portion 1590) relative to a second electrode 1532 (not shown) of anode assembly 1530 (not shown) to maintain a discharge gap 1540 (not shown) (e.g., discharge gap 340 (FIG. 3)). Cathode assembly 1520 may be part of electrode assembly 1560. Cathode assembly 1520 may be similar to cathode assembly 320 (FIG. 3). As shown in FIG. 15, cathode assembly 1520 may include bolt 1522, first electrode 1528, a gasket 1526, rod 1580, and tip portion 1590.

[0251] Bolt 1522 may be configured to transfer a charge (e.g., high negative charge) to first electrode 1528 (e.g., a cathode) via a power source (e.g., one or more capacitors) to generate a discharge plasma. Bolt 1522 may be coupled (e.g., electrically) to one or first plurality of capacitors and one or second plurality of capacitors (e.g., first and second plurality of capacitors 324, 326 (FIG. 3)). In some embodiments, bolt 1522 may be fixed in position (e.g., immovable). As shown in FIG. 15, bolt 1522 may include a recess 1523 and a longitudinal bore 1524 to accommodate rod 1580 through bolt 1522. Recess 1523 may be configured to accommodate a portion of rod 1580 within bolt 1522. In some embodiments, recess 1523 may be a countersink in bolt 1522 to receive a proximal end 1581 of rod 1580. In some embodiments, proximal end 1581 may be flush or below a top surface of bolt 1522 to ensure proper charge transfer (e.g., from one or more capacitors). In some embodiments, recess 1523 may be a depth (along +Z axis) equivalent to a travel distance of rod 1580 (e.g., a range of 1 mm to 10 mm). As shown in FIG. 15, a distal end of bolt 1522 may be coupled to first electrode 1528 to transfer a charge to first electrode 1528 and secure first electrode 1528 in place. In some embodiments, bolt 1522 may be secured (e.g., screwed) into first electrode 1528, for example, by one or more threads.2023P00384W001 51

[0252] First electrode 1528 may be configured to transfer a charge (e.g., high negative charge) from bolt 1522 to tip portion 1590 to generate a discharge plasma. First electrode 1528 (e.g., a cathode) may be similar to first electrode 322 of gas discharge chamber 300. First electrode 1528 may be coupled (e.g., electrically) to a distal end of bolt 1522 and one or more portions of tip portion 1590 to transfer charge to tip portion 1590. As shown in FIG. 15, first electrode 1528 may include a recess 1529 (e.g., a void) coupled to longitudinal bore 1524 to accommodate a portion of rod 1580 and a portion of tip portion 1590 within first electrode 1528. Recess 1529 may be configured to accommodate a portion of rod 1580 and a portion of tip portion 1590 within first electrode 1528. In some embodiments, recess 1529 may form a gap 1529a in first electrode 1528 configured to accommodate movement of tip portion 1590 through gap 1529a (e.g., along Z-axis) and maintain electrical contact between first electrode 1528 and tip portion 1590. In some embodiments, gap 1529a may have a width equal to or slightly greater than a width of tip portion 1590 (e.g., a range of 1 mm to 5 mm). In some embodiments, first electrode 1528 may include a low erosion rate material or alloy, for example, tungsten, tungsten-copper, alumina- copper, platinum, carbon, carbon-graphite, pyrolytic graphite, boron nitride, stainless steel, high chromium alloy, yttrium oxide-carbon composite, carbon fiber-alumina-copper composite, or a combination thereof.

[0253] Longitudinal bore 1524 may be configured to extend through bolt 1522 and accommodate a portion of rod 1580 to connect to tip portion 1590. Longitudinal bore 1524 may be further configured to extend through first electrode 1528 and couple to recess 1529. In some embodiments, longitudinal bore 1524 may extend through bolt 1522 and first electrode 1528 to accommodate movement (e.g., translation) of rod 1580 and tip portion 1590 (e.g., via recess 1529 and gap 1529a). As shown in FIG. 15, longitudinal bore 1524 may extend along a longitudinal axis 1521 of bolt 1522 and allow rod 1580 to connect to tip portion 1590 (e.g., via a connector 1585) and translate along longitudinal axis 1521 (along +Z axis). In some embodiments, longitudinal bore 1524 may have a diameter that is at least equal to a diameter of rod 1580. In some embodiments, recess 1523 and / or longitudinal bore 1524 may be coated with an electrically insulating material, for example, a ceramic insulator (e.g., clay, porous clay, glass, zirconia, alumina, steatite, cordierite, spinel, wollastonite, or a combination thereof) or any other rigid insulating (e.g., non-conductive) material. In some embodiments, longitudinal bore 1524 may extend through first electrode 1528 and accommodate a portion of rod 1580 and a portion of tip portion 1590. In some embodiments, longitudinal bore 1524 may extend from bolt 1522 into recess 1529 and gap 1529a of first electrode 1528.

[0254] Gasket 1526 may be configured to maintain a pressure of a gas discharge medium (e.g., gas discharge medium 301 (FIG. 3)) within gas discharge chamber 1500. As shown in FIG. 15, gasket 1526 may be disposed between bolt 1522 and rod 1580. In some embodiments, gasket 1526 may be disposed between first electrode 1528 and rod 1580 (e.g., within recess 1529). In some embodiments, gasket 1526 may be configured to seal rod 1580 to bolt 1522 and prevent any gas discharge medium from reaching a body (proximal) portion of bolt 1522. In some embodiments, gasket 1526 may be configured2023P00384W001 52 to seal (e.g. fix) rod 1580 within bolt 1522 (e.g., within longitudinal bore 1524). In some embodiments, gasket 1526 may include one or more gaskets along rod 1580. In some embodiments, gasket 1526 may include a metallic material (e.g., copper, brass, aluminum, etc.), a non-metallic material (e.g., rubber, graphite, PTFE, etc.), or a combination thereof. In some embodiments, gasket 1526 may include one or more O -rings.

[0255] Rod 1580 may be configured to adjust a position of tip portion 1590 (e.g., first discharge surface 1592) to maintain a discharge gap (e.g., discharge gap 340 (FIG. 3)). Rod 1580 may be further configured to extend through longitudinal bore 1524 of bolt 1522 and transfer a portion of charge from bolt 1522 to tip portion 1590. In some embodiments, rod 1580 may be further configured to extend through a portion of recess 1529 of first electrode 1528 (e.g., through gap 1529a). As shown in FIG. 15, rod 1580 may include proximal end 1581, a distal end 1582, threads 1584, and a connector 1585. In some embodiments, rod 1580 may include a metallic material (e.g., tungsten, stainless steel, copper, brass, aluminum, etc.), a non-metallic material (e.g., ceramic, alumina, graphite, etc.), or a combination thereof. In some embodiments, proximal end 1581 of rod 1580 may be non-metallic and distal end 1582 may be metallic. In some embodiments, all of rod 1580 may be a conductive material (e.g., metal, tungsten, stainless steel, copper, brass, aluminum, etc.). In some embodiments, rod 1580 may include a low erosion rate material or alloy, for example, tungsten, tungsten-copper, alumina-copper, platinum, carbon, carbon-graphite, pyrolytic graphite, boron nitride, stainless steel, high chromium alloy, yttrium oxide-carbon composite, carbon fiber-alumina-copper composite, or a combination thereof.

[0256] In some embodiments, proximal end 1581 of rod 1580 may include a cap or a head configured to insert into recess 1523. In some embodiments, the cap or head may be configured for adjustment (e.g., rotation) via a manual tool (e.g., Allen wrench, hex key, etc.). In some embodiments, for example, proximal end 1581 of rod 1580 may include a bolt with a socket for manual adjustment (e.g., hex head, socket head, etc.) by an operator. In some embodiments, rod 1580 may omit proximal end 1581 (e.g., cap, head, etc.) and include only a cylindrical rod (e.g., threaded cylindrical rod with a countersunk notch for an adjustment tool). In some embodiments, for example, a proximal end of the cylindrical rod may be attached or connected to an actuator (e.g., mechanical, etc.) situated within bolt 1522 and configured to rotate rod 1580 (e.g., via threads 1584) and / or translate rod 1580 along longitudinal bore 1524 (e.g., along +Z axis).

[0257] In some embodiments, rod 1580 may include threads 1584 configured to secure rod 1580 to bolt 1522 and adjust a position of rod 1580 along longitudinal bore 1524 (e.g., via rotation). In some embodiments, threads 1584 may include external threads (grooves) on rod 1580 and corresponding internal threads (grooves) in bolt 1522 along longitudinal bore 1524 or vice versa. In some embodiments, threads 1584 may include fine thread adjustment screws such that each rotation corresponds to a specific translation of rod 1580 along longitudinal bore 1524 (e.g., 0.1 mm travel per revolution, 10 microns (pm) travel per revolution, 1 pm travel per revolution, etc.). In some2023P00384W001 53 embodiments, threads 1584 may be formed near proximal end 1581 of rod 1580 and below recess 1523 in bolt 1522.

[0258] In some embodiments, as shown in FIG. 15, rod 1580 may be configured to translate along longitudinal bore 1524. In some embodiments, rod 1580 may also be configured to translate within recess 1529 of first electrode 1528. In some embodiments, for example, rod 1580 may be rotated by a first applied force 1586 (e.g., rotational motion, CW) and thereby translate along longitudinal bore 1524 by a second applied force 1587 (e.g., linear motion, +Z axis) to thereby adjust a position of first discharge surface 1592 of tip portion 1590. In some embodiments, rod 1580 may omit threads 1584 and include an unthreaded (smooth) cylindrical rod. In some embodiments, for example, a proximal end of the cylindrical rod may be attached or connected to an actuator (e.g., mechanical, etc.) situated within or above bolt 1522 and configured to translate rod 1580 along longitudinal bore 1524 (e.g., along +Z axis).

[0259] As shown in FIG. 15, distal end 1582 of rod 1580 may be connected to tip portion 1590. In some embodiments, rod 1580 may include connector 1585 configured to secure tip portion 1590 to distal end 1582 of rod 1580. In some embodiments, connector 1585 may include a joint that secures tip portion 1590 to rod 1580 but allows rod 1580 to freely rotate (e.g., thereby allowing translation along +Z axis for a threaded rod as rod 1580 is rotated). In some embodiments, for example, connector 1585 may include a spheroid joint (e.g., a ball-and-socket joint, etc.). In some embodiments, tip portion 1590 may be rigidly connected to distal end 1582 of rod 1580 via connector 1585. In some embodiments, for example, connector 1585 may include a welded joint, a threaded joint, a bolted joint, a riveted joint, a mechanical joint, an interlocking joint, or any other suitable joint to secure tip portion 1590 to rod 1580.

[0260] In some embodiments, as shown in FIG. 15, connector 1585 may include a joint that allows for rotation of rod 1580. For example, connector 1585 (e.g., a spheroid joint) may secure tip portion 1590 to rod 1580 when rod 1580 is rotated by first applied force 1586 (e.g., rotational motion, CW) and thereby translate along longitudinal bore 1524 by second applied force 1587 (e.g., linear motion, +Z axis) to adjust a position of first discharge surface 1592 of tip portion 1590.

[0261] Tip portion 1590 may be configured to adjust a position of first discharge surface 1592 and maintain the discharge gap (e.g., discharge gap 340 (FIG. 3) overtime. Tip portion 1590 may be further configured to act as a sacrificial layer and erode over time during operation of gas discharge chamber 1500 to protect first electrode 1528 from eroding during plasma discharge. As shown in FIG. 15, tip portion 1590 may be coupled to distal end 1582 of rod 1580 and include first discharge surface 1592 (e.g., at a distal or bottom surface of tip portion 1590). In some embodiments, first discharge surface 1592 may include a bump or a convex curvature to focus or direct the plasma discharge. In some embodiments, tip portion 1590 may include a metallic material (e.g., tungsten, stainless steel, copper, brass, aluminum, etc.). In some embodiments, tip portion 1590 may include a low erosion rate material or alloy, for example, tungsten, tungsten-copper, alumina-copper, platinum, carbon, carbon-graphite,2023P00384W001 54 pyrolytic graphite, boron nitride, stainless steel, high chromium alloy, yttrium oxide-carbon composite, carbon fiber-alumina-copper composite, or a combination thereof.Example Cathode Assembly with Rotational Rod

[0262] FIG. 16 illustrates gas discharge chamber 1500 with a cathode assembly 1520', according to an example embodiment. Although cathode assembly 1520' is shown in FIG. 16 as a stand-alone apparatus and / or system, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1-3, 15, and 17-20, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, gas discharge chamber 1500, flow diagram 2000, and / or any suitable metrology / inspection systems.

[0263] The embodiments of cathode assembly 1520 shown in FIG. 15, for example, and the embodiments of cathode assembly 1520' shown in FIG. 16 may be similar. Similar reference numbers are used to indicate features of the embodiments of cathode assembly 1520 shown in FIG. 15 and the similar features of the embodiments of cathode assembly 1520' shown in FIG. 16. A difference between the embodiments of cathode assembly 1520 shown in FIG. 15 and the embodiments of cathode assembly 1520' shown in FIG. 16 is that cathode assembly 1520' includes threads 1585' at distal end 1582 of a rod 1580' that connect to tip portion 1590 and adjust a position of first discharge surface 1592 by a third applied force 1594 (e.g., translation, +Z axis) when rod 1580' is rotated (e.g., a first applied force 1586'), rather than cathode assembly 1520 with threads 1584 and connector 1585 of rod 1580 as shown in FIG. 15.

[0264] As shown in FIG. 16, cathode assembly 1520' may include bolt 1522, first electrode 1528, gasket 1526, rod 1580', and tip portion 1590. Cathode assembly 1520' is similar to cathode assembly 1520 shown in FIG. 15 and similar reference numbers are used to indicate the similar features of cathode assembly 1520 shown in FIG. 15 and cathode assembly 1520' shown in FIG. 16. Discussion of cathode assembly 1520' components and / or functionality (e.g., bolt 1522, first electrode 1528, gasket 1526, tip portion 1590, etc.) is not duplicated here for brevity, but the embodiments and features of each are similar to cathode assembly 1520 described above.

[0265] Cathode assembly 1520' may include rod 1580'. Rod 1580' may be configured to adjust a position of tip portion 1590 (e.g., first discharge surface 1592) to maintain a discharge gap (e.g., discharge gap 340 (FIG. 3)). Rod 1580' may be further configured to extend through longitudinal bore 1524 of bolt 1522 and transfer charge from bolt 1522 to tip portion 1590. As shown in FIG. 16, rod 1580' may include threads 1585' at distal end 1582 to connect to tip portion 1590.

[0266] Threads 1585' may be configured to interlock rod 1580' to tip portion 1590 and adjust aposition of first discharge surface 1592 along the Z-axis (e.g., via rotation, CCW) when rod 1580' is rotated. In some embodiments, threads 1585' may include fine thread adjustment screws such that each rotation corresponds to a specific translation (e.g., third applied force 1594) of tip portion 1590 away from rod 1580' along the Z-axis (e.g., 0. 1 mm travel per revolution, 10 pm travel per revolution, 1 pm travel per revolution, etc.). In some embodiments, as shown in FIG. 16, rod 1580' may be configured to rotate2023P00384W001 55 within longitudinal bore 1524. In some embodiments, for example, rod 1580' may be rotated by a first applied force 1586' (e.g., rotational motion, CCW) and thereby rotate threads 1585' to translate tip portion 1590 by third applied force 1594 (e.g., linear motion, +Z axis) to thereby adjust a position of first discharge surface 1592 of tip portion 1590.Example Cathode Assembly with Conductive Flexure

[0267] FIG. 17 illustrates gas discharge chamber 1500 with a cathode assembly 1520", according to an example embodiment. Although cathode assembly 1520" is shown in FIG. 17 as a stand-alone apparatus and / or system, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1-3, 15, 16, and 18-20, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, gas discharge chamber 1500, flow diagram 2000, and / or any suitable metrology / inspection systems.

[0268] The embodiments of cathode assembly 1520 shown in FIG. 15, for example, and the embodiments of cathode assembly 1520" shown in FIG. 17 may be similar. Similar reference numbers are used to indicate features of the embodiments of cathode assembly 1520 shown in FIG. 15 and the similar features of the embodiments of cathode assembly 1520" shown in FIG. 17. A difference between the embodiments of cathode assembly 1520 shown in FIG. 15 and the embodiments of cathode assembly 1520" shown in FIG. 17 is that cathode assembly 1520" includes a conductive flexure 1595 between rod 1580 and tip portion 1590, rather than cathode assembly 1520 with rod 1580 and tip portion 1590 as shown in FIG. 15.

[0269] As shown in FIG. 17, cathode assembly 1520" may include bolt 1522, first electrode 1528, gasket 1526, rod 1580, tip portion 1590, and conductive flexure 1595. Cathode assembly 1520" is similar to cathode assembly 1520 shown in FIG. 15 and similar reference numbers are used to indicate the similar features of cathode assembly 1520 shown in FIG. 15 and cathode assembly 1520" shown in FIG. 17. Discussion of cathode assembly 1520" components and / or functionality (e.g., bolt 1522, first electrode 1528, gasket 1526, rod 1580, connector 1585, tip portion 1590, etc.) is not duplicated here for brevity, but the embodiments and features of each are similar to cathode assembly 1520 described above.

[0270] Cathode assembly 1520" may include conductive flexure 1595. Conductive flexure 1595 may be configured to maintain electrical connection (charge) between bolt 1522, first electrode 1528, and tip portion 1590. Conductive flexure 1595 may be further configured to apply an upward restoring force to rod 1580 (e.g., to balance rod 1580 in a vertical position along Z-axis). As shown in FIG. 17, conductive flexure 1595 may be disposed between bolt 1522 and tip portion 1590 to maintain electrical connection (charge). In some embodiments, as shown in FIG. 17, conductive flexure 1595 may be disposed within recess 1529 of first electrode 1528 and coupled (secured) to first electrode 1528 (e.g., via first and second screws 1596a, 1596b). In some embodiments, conductive flexure 1595 may include a metallic shim (e.g., tungsten, stainless steel, copper, brass, aluminum, etc.). In some embodiments, conductive flexure 1595 may include a flexible low erosion rate material or alloy, for example, tungsten,2023P00384W001 56 tungsten-copper, alumina-copper, platinum, carbon, carbon-graphite, pyrolytic graphite, boron nitride, stainless steel, high chromium alloy, yttrium oxide-carbon composite, carbon fiber-alumina-copper composite, or a combination thereof.

[0271] In some embodiments, conductive flexure 1595 may be configured to flex (e.g., via second applied force 1587 from rod 1580) and thereby adjust a position of first discharge surface 1592 (e.g., translate along Z-axis). In some embodiments, for example, rod 1580 may be rotated by first applied force 1586 (e.g., rotational motion, CCW) and thereby translate along longitudinal bore 1524 by second applied force 1587 (e.g., linear motion, +Z axis) to flex conductive flexure 1595 (e.g., convex flexure, +Z axis) and thereby adjust a position of first discharge surface 1592 of tip portion 1590.

[0272] In some embodiments, cathode assembly 1520" may include first and second screws 1596a, 1596b coupled to conductive flexure 1595 to secure conductive flexure 1595 in position (e.g., to a surface of first electrode 1528 within recess 1529). In some embodiments, first and second screws 1596a, 1596b may be configured to adjust a position of conductive flexure 1595 (e.g., along Z-axis) and / or a tension of conductive flexure by rotating first and second screws 1596a, 1596b. In some embodiments, for example, first and second screws 1596a, 1596b may be connected to first electrode 1528 (e.g., via threads). In some embodiments, for example, first and second screws 1596a, 1596b may be connected to base 1510 (e.g., via threads).Example Cathode Assembly with Plug

[0273] FIG. 18 illustrates gas discharge chamber 1500 with a cathode assembly 1520"', according to an example embodiment. Although cathode assembly 1520"' is shown in FIG. 18 as a stand-alone apparatus and / or system, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1-3, 15-17, 19, and 20, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, gas discharge chamber 1500, flow diagram 2000, and / or any suitable metrology / inspection systems.

[0274] The embodiments of cathode assembly 1520" shown in FIG. 17, for example, and the embodiments of cathode assembly 1520'" shown in FIG. 18 may be similar. Similar reference numbers are used to indicate features of the embodiments of cathode assembly 1520" shown in FIG. 17 and the similar features of the embodiments of cathode assembly 1520'" shown in FIG. 18. A difference between the embodiments of cathode assembly 1520" shown in FIG. 17 and the embodiments of cathode assembly 1520'" shown in FIG. 18 is that cathode assembly 1520'" includes a plug 1598 having one or more precision length tips 1598a, 1598b, 1598c to adjust a position of a rod 1580" and thereby adjust first discharge surface 1592, rather than cathode assembly 1520" with rod 1580 and threads 1584 as shown in FIG. 17.

[0275] As shown in FIG. 18, cathode assembly 1520'" may include bolt 1522, first electrode 1528, gasket 1526, rod 1580", tip portion 1590, conductive flexure 1595, and plug 1598. Cathode assembly 1520'" is similar to cathode assembly 1520" shown in FIG. 17 and similar reference numbers are used to indicate the similar features of cathode assembly 1520" shown in FIG. 17 and cathode assembly2023P00384W001 571520"' shown in FIG. 18. Discussion of cathode assembly 1520"' components and / or functionality (e.g., bolt 1522, first electrode 1528, gasket 1526, tip portion 1590, conductive flexure 1595, etc.) is not duplicated here for brevity, but the embodiments and features of each are similar to cathode assembly 1520" described above.

[0276] Cathode assembly 1520'" may include plug 1598. Plug 1598 may be configured to couple to rod 1580" and adjust a length (position) of rod 1580" along longitudinal bore 1524 and thereby adjust a position of first discharge surface 1592 of tip portion 1590. In some embodiments, plug 1598 may include a metallic material (e.g., tungsten, stainless steel, copper, brass, aluminum, etc.), a non-metallic material (e.g., ceramic, alumina, graphite, PTFE, etc.), or a combination thereof. In some embodiments, plug 1598 may be inserted into one or more recesses of bolt 1522 (e.g., first recess 1523a, second recess 1523b, third recess 1523c, etc.) to adjust rod 1580" to one or more corresponding positions along longitudinal bore 1524. In some embodiments, plug 1598 may include one or more threads to secure (fix) plug 1598 along longitudinal axis 1521 at a specific distance relative to a proximal end of bolt 1522 (e.g., 1 mm, 2 mm, 3 mm). In some embodiments, plug 1598 may include one or more precision length tips 1598a, 1598b, 1598c to adjust rod 1580" along longitudinal bore 1524 to corresponding different positions (e.g., first precision length tip 1598a of 1 mm length, second precision length tip 1598b of 2 mm length, third precision length tip 1598a of 3 mm length).

[0277] As shown in FIG. 18, plug 1598 may include first precision length tip 1598a, second precision length tip 1598b, and third precision length tip 1598c. First, second, and third precision length tips 1598a, 1598b, 1598c may be configured to selectively adjust a position of rod 1580" (e.g., position of distal end 1582) and thereby selectively adjust a position of first discharge surface 1592. In some embodiments, bolt 1522 may include first recess 1523a, second recess 1523b, and third recess 1523c to receive corresponding first, second, and third precision length tips 1598a, 1598b, 1598c, respectively. In some embodiments, first, second, and third precision length tips 1598a, 1598b, 1598c may include precision length threads such that when secured within bolt 1522 provide a known length adjustment to rod 1580" (e.g., 1 mm, 2 mm, 3 mm) and thereby adjust a position of first discharge surface 1592 along +Z axis accordingly. In some embodiments, as shown in FIG. 18, rod 1580" may include threads 1585' at distal end 1582 to extend through conductive flexure 1595 and connect (secure) to tip portion 1590.

[0278] In some embodiments, as shown in FIG. 18, plug 1598 may be inserted (secured) into bolt 1522 (e.g., first precision length tip 1598a secured into first recess 1523a) and thereby translate rod 1580" by second applied force 1587' (e.g., linear motion, +Z axis) along longitudinal bore 1524 to flex conductive flexure 1595 (e.g., convex flexure, +Z axis) and thereby translate tip portion 1590 by third applied force 1594 (e.g., linear motion, +Z axis) and thereby adjust a position of first discharge surface 1592 of tip portion 1590. In some embodiments, plug 1598 may be sequentially applied (e.g., via manual intervention) to adjust rod 1580" and first discharge surface 1592 over time (e.g., based on the number of pulses of gas discharge chamber 1500) to maintain the discharge gap (e.g., discharge gap 340 (FIG. 3).2023P00384W001 58

[0279] In some embodiments, for example, plug 1598 may include first precision length tip 1598a (e.g., having a length of 1 mm) applied after a first period of time (e.g., at 30 Bp) and thereby adjust first discharge surface 1592 along +Z axis by a length of first precision length tip 1598a (e.g., 1 mm) to account for electrode erosion of tip portion 1590 and maintain the discharge gap . In some embodiments, for example, first precision length tip 1598a (e.g., having a length of 1 mm) may span first recess 1523a of bolt 1522 to apply second applied force 1587' (e.g., linear motion, +Z axis) and translate rod 1580" accordingly (e.g., translate rod 1580" a distance of 1 mm along +Z axis). In some embodiments, for example, plug 1598 may include second precision length tip 1598b (e.g., having a length of 2 mm) applied after a second period of time (e.g., at 60 Bp) and thereby adjust first discharge surface 1592 along +Z axis by a length of second precision length tip 1598a (e.g., 2 mm) to account for electrode erosion of tip portion 1590 and maintain the discharge gap. In some embodiments, for example, second precision length tip 1598b (e.g., having a length of 2 mm) may span first recess 1523a and second recess 1523b of bolt 1522 to apply second applied force 1587' (e.g., linear motion, +Z axis) and translate rod 1580" accordingly (e.g., translate rod 1580" a distance of 2 mm along +Z axis). In some embodiments, for example, plug 1598 may include third precision length tip 1598c (e.g., having a length of 3 mm) applied after a third period of time (e.g., at 90 Bp) and thereby adjust first discharge surface 1592 along +Z axis by a length of third precision length tip 1598c (e.g., 3 mm) to account for electrode erosion of tip portion 1590 and maintain the discharge gap. In some embodiments, for example, third precision length tip 1598c (e.g., having a length of 3 mm) may span first recess 1523a, second recess 1523b, and third recess 1523c of bolt 1522 to apply second applied force 1587' (e.g., linear motion, +Z axis) and translate rod 1580" accordingly (e.g., translate rod 1580" a distance of 3 mm along +Z axis).Example Cathode Assembly with Actuator

[0280] FIG. 19 illustrates gas discharge chamber 1500 with a cathode assembly 1520"", according to an example embodiment. Although cathode assembly 1520"" is shown in FIG. 19 as a stand-alone apparatus and / or system, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited to, elements in FIGS. 1-3, 15-18, and 20, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, gas discharge chamber 1500, flow diagram 2000, and / or any suitable metrology / inspection systems.

[0281] The embodiments of cathode assembly 1520'" shown in FIG. 18, for example, and the embodiments of cathode assembly 1520"" shown in FIG. 19 may be similar. Similar reference numbers are used to indicate features of the embodiments of cathode assembly 1520'" shown in FIG. 18 and the similar features of the embodiments of cathode assembly 1520"" shown in FIG. 19. A difference between the embodiments of cathode assembly 1520'" shown in FIG. 18 and the embodiments of cathode assembly 1520"" shown in FIG. 19 is that cathode assembly 1520"" includes an actuator 1598' (e.g., manual, automatic) to adjust a position of rod 1580" and thereby adjust first discharge surface 1592, rather than cathode assembly 1520'" with plug 1598 having precision length tips 1598a, 1598b, 1598c as shown in FIG. 18.2023P00384W001 59

[0282] As shown in FIG. 19, cathode assembly 1520"" may include bolt 1522, first electrode 1528, gasket 1526, rod 1580", tip portion 1590, conductive flexure 1595, and actuator 1598'. Cathode assembly 1520"" is similar to cathode assembly 1520"' shown in FIG. 18 and similar reference numbers are used to indicate the similar features of cathode assembly 1520'" shown in FIG. 18 and cathode assembly 1520"" shown in FIG. 19. Discussion of cathode assembly 1520"" components and / or functionality (e.g., bolt 1522, first electrode 1528, gasket 1526, rod 1580", tip portion 1590, conductive flexure 1595, etc.) is not duplicated here for brevity, but the embodiments and features of each are similar to cathode assembly 1520'" described above.

[0283] Cathode assembly 1520"" may include actuator 1598'. Actuator 1598' may be configured to couple to rod 1580" and adjust a position of rod 1580" along longitudinal bore 1524 and thereby adjust aposition of first discharge surface 1592 of tip portion 1590. In some embodiments, actuator 1598' may be further configured to adjust a position of rod 1580" along longitudinal bore 1524 and thereby adjust a position of first discharge surface 1592 of tip portion 1590 based on one or more parameters of gas discharge chamber 1500 (e.g., a number of light pulses).

[0284] In some embodiments, actuator 1598' may include a mechanical (non-electric) actuator (e.g., manual adjuster, precision micrometer head, precision adjustment screw, cam, pneumatic, hydraulic, magnetic, etc.). In some embodiments, for example, actuator 1598' may include a precision micrometer head for manual adjustment (e.g., 0.1 mm travel per revolution, 10 pm travel per revolution, 1 pm travel per revolution, etc.) by operator intervention. In some embodiments, for example, cathode assembly 1520"" may further include an insulator 1599 disposed between actuator 1598' and bolt 1522 to reduce the risk of charge conduction (e.g., short-circuit, arcing, etc.) from bolt 1522 to actuator 1598'. In some embodiments, insulator 1599 may include a ceramic insulator (e.g., clay, porous clay, glass, zirconia, alumina, steatite, cordierite, spinel, wollastonite, or a combination thereof) or any other rigid insulating (e.g., non-conductive) material.

[0285] In some embodiments, actuator 1598' may be inserted into recess 1523' of bolt 1522 to adjust rod 1580" to one or more positions along longitudinal bore 1524. In some embodiments, actuator 1598' may include one or more threads to secure (fix) actuator 1598' along longitudinal axis 1521 at a specific distance relative to a proximal end of bolt 1522. In some embodiments, actuator 1598' may include a precision adjustment screw to adjust (e.g., translate) rod 1580" along longitudinal bore 1524 to different positions (e.g., 1 mm length, 2 mm length, 3 mm length, etc.).

[0286] As shown in FIG. 19, actuator 1598' may be coupled to proximal end 1581 of rod 1580" and configured to selectively adjust a position of rod 1580" (e.g., position of distal end 1582) and thereby selectively adjust a position of first discharge surface 1592. In some embodiments, bolt 1522 may include recess 1523' to receive actuator 1598'. In some embodiments, as shown in FIG. 19, a portion of recess 1523' may include insulator 1599 (e.g., non-conductive material) configured to isolate actuator 1598' from charge on bolt 1522 (e.g., high negative charge). In some embodiments, as shown in FIG. 19, actuator 1598' may be inserted (secured) into bolt 1522 (e.g., secured into recess 1523') and thereby2023P00384W001 60 translate rod 1580" by second applied force 1587' (e.g., linear motion, +Z axis) along longitudinal bore 1524 to flex conductive flexure 1595 (e.g., convex flexure, +Z axis) and thereby translate tip portion 1590 by third applied force 1594 (e.g., linear motion, +Z axis) and thereby adjust a position of first discharge surface 1592 of tip portion 1590.

[0287] In some embodiments, actuator 1598' may be sequentially applied (e.g., via manual intervention or an automated process) to adjust rod 1580" and first discharge surface 1592 overtime (e.g., based on the number of pulses of gas discharge chamber 1500) to maintain the discharge gap (e.g., discharge gap 340 (FIG. 3). In some embodiments, for example, actuator 1598' may translate rod 1580" a first distance along the Z-axis (e.g., a distance of 1 mm) after a first period of time (e.g., at 30 Bp) and thereby adjust first discharge surface 1592 along +Z axis by the first distance (e.g., 1 mm) to account for electrode erosion of tip portion 1590 and maintain the discharge gap . In some embodiments, for example, actuator 1598' may translate rod 1580" a second distance along the Z-axis (e.g., a distance of 2 mm) after a second period of time (e.g., at 60 Bp) and thereby adjust first discharge surface 1592 along +Z axis by the second distance (e.g., 2 mm) to account for electrode erosion of tip portion 1590 and maintain the discharge gap. In some embodiments, for example, actuator 1598' may translate rod 1580" a third distance along the Z-axis (e.g., a distance of 3 mm) after a third period of time (e.g., at 90 Bp) and thereby adjust first discharge surface 1592 along +Z axis by the third distance (e.g., 3 mm) to account for electrode erosion of tip portion 1590 and maintain the discharge gap. In some embodiments, adjustment of rod 1580" by actuator 1598' may be based on a parameter of gas discharge chamber 1500, for example, a number of pulses.Example Flow Diagram

[0288] FIG. 20 illustrates flow diagram 2000, according to an example embodiment. For example, flow diagram 2000 may be for pulsed light source 210 shown in FIG. 2. For example, flow diagram 2000 may be for gas discharge chamber 300 shown in FIG. 3. For example, flow diagram 2000 may be for gas discharge chamber 1500 shown in FIGS. 15-19. Flow diagram 2000 may be configured to determine one or more parameters of a light source (e.g., a number of pulses). Flow diagram 2000 may be further configured to adjust a discharge gap of electrode assembly 1560 based on the one or more parameters. Flow diagram 2000 may be further configured to maintain a discharge gap based on the one or more parameters. Flow diagram 2000 may be further configured to reduce errors in a generated light beam, reduce errors in a lithographic process, and increase lifetime of the light source (e.g., pulsed light source 210 (FIG. 2)).

[0289] It is to be appreciated that not all steps in FIG. 20 are needed to perform the disclosure provided herein. Further, some of the steps may be performed simultaneously, sequentially, and / or in a different order than shown in FIG. 20. Flow diagram 2000 shall be described with reference to FIGS. 1-3, 15- 19, and 22. However, flow diagram 2000 is not limited to those example embodiments.

[0290] Although flow diagram 2000 is shown in FIG. 20 as a stand-alone method, the embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, such as, but not limited2023P00384W001 61 to, elements in FIGS. 1-3 and 15-20, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, gas discharge chamber 1500, cathode assembly 1520, cathode assembly 1520', cathode assembly 1520", cathode assembly 1520"', cathode assembly 1520"", and / or any suitable metrology / inspection systems. In some embodiments, flow diagram 2000 may be implemented by pulsed light source 210 shown in FIG. 2 (e.g., via a controller or control system 140). In some embodiments, flow diagram 2000 may be implemented by gas discharge chamber 300 shown in FIG. 3 (e.g., via a controller or control system 140). In some embodiments, flow diagram 2000 may be implemented by gas discharge chamber 1500 shown in FIGS. 15-19 (e.g., via a controller or control system 140).

[0291] In operation 2002, as shown in the example of FIGS. 1-19 and 22, one or more parameters of a light source may be determined (e.g., measured). In some embodiments, a number of pulses generated by the light source may be determined (e.g., via control system 140). In some embodiments, the parameter(s) may be measured periodically (e.g., a position of first electrode 1528, an erosion rate of first electrode 1528, a position of second electrode 1532, an erosion rate of second electrode 1532, a number of pulses, a pulse rate, or a combination thereof), for example, by one or more sensors or predetermined trends (e.g., an average). In some embodiments, the parameter(s) may be measured in real-time or near real-time.

[0292] In some embodiments, for example, the erosion rate of first electrode 1528 may be predetermined based on a measured average rate for one or more similar gas discharge chambers. In some embodiments, for example, the erosion rate of first electrode 1528 may be determined or correlated to a pulse repetition rate (e.g., 4 kHz, 8 kHz, 16 kHz, etc.) and / or a number of pulses of gas discharge chamber 1500.

[0293] In operation 2004, as shown in the example of FIGS. 1-19 and 22, a position of a first discharge surface (e.g., first discharge surface 1592 (FIG. 15)) of a first electrode assembly (e.g., cathode assembly 1520) may be adjusted based on the one or more parameters (e.g., the number of pulses) to adjust a discharge gap (e.g., discharge gap 340 (FIG. 3)) between first and second electrodes 1522, 1532. In some embodiments, the discharge gap may be adjusted by adjusting a position of first discharge surface 1592 via cathode assembly 1520 (e.g., via bolt 1522, rod 1580, and tip portion 1590) based on the one or more parameters.

[0294] In operation 2006, optionally, as shown in the example of FIGS. 1-19 and 22, adjusting the position of the first discharge surface may include translating a rod (e.g., rod 1580) of the first electrode assembly (e.g., cathode assembly 1520) along a longitudinal bore (e.g., longitudinal bore 1524) of a first electrode (e.g., bolt 1522). In some embodiments, as shown in FIG. 15, rod 1580 may be rotated by first applied force 1586 (e.g., rotational motion, CW) and thereby translate along longitudinal bore 1524 by second applied force 1587 (e.g., linear motion, +Z axis) to thereby adjust a position of first discharge surface 1592 of tip portion 1590.2023P00384W001 62

[0295] In operation 2008, optionally, as shown in the example of FIGS. 1-19 and 22, adjusting the position of the first discharge surface may include rotating a rod (e.g., rod 1580') of the first electrode assembly (e.g., cathode assembly 1520') within a longitudinal bore (e.g., longitudinal bore 1524) of bolt 1522. In some embodiments, as shown in FIG. 16, rod 1580' may be rotated by first applied force 1586' (e.g., rotational motion, CCW) and thereby rotate threads 1585' to translate tip portion 1590 by third applied force 1594 (e.g., linear motion, +Z axis) to thereby adjust a position of first discharge surface 1592 of tip portion 1590.

[0296] In operation 2010, optionally, as shown in the example of FIGS. 1-19 and 22, adjusting the position of the first discharge surface may include inserting a plug (e.g., plug 1598) of the first electrode assembly (e.g., cathode assembly 1520'") into a longitudinal bore (e.g., longitudinal bore 1524) of bolt 1522. In some embodiments, as shown in FIG. 18, plug 1598 may be inserted (secured) into bolt 1522 (e.g., first precision length tip 1598a secured into first recess 1523a) and thereby translate rod 1580" by second applied force 1587' (e.g., linear motion, +Z axis) along longitudinal bore 1524 to flex conductive flexure 1595 (e.g., convex flexure, +Z axis) and thereby translate tip portion 1590 by third applied force 1594 (e.g., linear motion, +Z axis) and thereby adjust a position of first discharge surface 1592 of tip portion 1590.

[0297] In operation 2012, optionally, as shown in the example of FIGS. 1-19 and 22, adjusting the position of the first discharge surface may include adjusting a rod (e.g., rod 1580") of the first electrode assembly (e.g., cathode assembly 1520"") with an actuator (e.g., actuator 1598'). In some embodiments, actuator 1598' may include a mechanical (non-electric) actuator (e.g., manual adjuster, precision micrometer head, precision adjustment screw, cam, pneumatic, hydraulic, magnetic, etc.). In some embodiments, as shown in FIG. 19, actuator 1598' may be coupled to proximal end 1581 of rod 1580" and configured to selectively adjust a position of rod 1580" (e.g., position of distal end 1582) and thereby selectively adjust a position of first discharge surface 1592. In some embodiments, as shown in FIG. 19, actuator 1598' may be inserted (secured) into bolt 1522 (e.g., secured into recess 1523') and thereby translate rod 1580" by second applied force 1587' (e.g., linear motion, +Z axis) along longitudinal bore 1524 to flex conductive flexure 1595 (e.g., convex flexure, +Z axis) and thereby translate tip portion 1590 by third applied force 1594 (e.g., linear motion, +Z axis) and thereby adjust a position of first discharge surface 1592 of tip portion 1590.

[0298] In some embodiments, the actuator may be adjusted based on a predetermined ratio. In some embodiments, the predetermined ratio may be based on an erosion rate of first electrode 1528 (e.g., an erosion rate of tip portion 1590). In some embodiments, the predetermined ratio may be based on a first rate of erosion of first electrode 1528 and a second rate of erosion of second electrode 1532 (not shown) of anode assembly 1530 (not shown).

[0299] In operation 2014, optionally, as shown in the example of FIGS. 1-19 and 22, a position of a second discharge surface (e.g., second discharge surface 346 (FIG. 3) of a second electrode (e.g., second2023P00384W001 63 electrode 332 (FIG. 3)) may be adjusted based on the one or more parameters (e.g., the number of pulses) to adjust the discharge gap.Example Electrode Assemblies with Actuator Assemblies

[0300] FIGS. 21A-21D illustrate cross-sectional views of electrode assemblies 2160A-2160D with actuator assemblies 2140A-2140D, respectively, according to some example embodiments. Although each of electrode assemblies 2160A-2160D are shown in FIGS. 21A-21D as a stand-alone apparatus and / or system, the embodiments of this disclosure can be used with other apparatuses, systems, and / or methods, such as, but not limited to, each electrode assembly and its associated components in FIGS. 1-3, 10-14, and 22, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge chamber 300, gas discharge chamber 1000, actuator assembly 1040, actuator assembly 1040', actuator assembly 1040", electrode assembly 1160, flow diagram 1400, computing system 2200, and / or any suitable metrology / inspection systems. The embodiments of electrode assemblies 2160A-2160D shown in FIGS. 21A-21D and, for example, and the embodiments of electrode assembly 360 shown in FIG. 3, electrode assembly 1060 shown in FIGS. 10 and 11, and electrode assembly 1160 shown in FIGS. 13 and 13A may be similar.

[0301] As shown in FIG. 21A, electrode assembly 2160A includes an electrode 2122A (e.g., a cathode) configured to receive a first applied force 2147A (e.g., translation, -X axis (a “push”)) and an actuator assembly 2140A (e.g., elevator mechanism) configured to transfer first applied force 2147A to a second applied force 2123A (e.g., translation, +Z axis) and thereby adjust a position of electrode 2122A along the Z-axis. In some embodiments, electrode assembly 2160A may include first and second securements 2130A, 2132A coupled to ends of an actuator 2128A (e.g., teeth) of actuator assembly 2140A to secure (fix) actuator 2128A in place to counteract first applied force 2147A and transfer it into second applied force 2123A. In some embodiments, as shown in FIG. 21 A, teeth of actuator 2128A may be oriented (e.g., sloped) to increase along a direction of first applied force 2147A (e.g., increase along -X axis) and extend toward a desired electrode 2122A direction of travel (e.g., +Z axis).

[0302] As shown in FIG. 21B, electrode assembly 2160B includes an electrode 2122B (e.g., a cathode) configured to receive a first applied force 2147B (e.g., translation, +X axis (a “pull”)) and an actuator assembly 2140B (e.g., elevator mechanism) configured to transfer first applied force 2147B to a second applied force 2123B (e.g., translation, +Z axis) and thereby adjust a position of electrode 2122B along the Z-axis. In some embodiments, electrode assembly 2160B may include first and second securements 2130B, 2132B coupled to ends of an actuator 2128B (e.g., teeth) of actuator assembly 2140B to secure (fix) actuator 2128B in place to counteract first applied force 2147B and transfer it into second applied force 2123B. In some embodiments, as shown in FIG. 2 IB, teeth of actuator 2128B may be oriented (e.g., sloped) to increase along a direction of first applied force 2147B (e.g., increase along +X axis) and extend toward a desired electrode 2122B direction of travel (e.g., +Z axis).

[0303] As shown in FIG. 21C, electrode assembly 2160C includes an electrode 2122C (e.g., an anode) configured to receive a first applied force 2147C (e.g., translation, -X axis (a “push”)) and an actuator2023P00384W001 64 assembly 2140C (e.g., elevator mechanism) configured to transfer first applied force 2147C to a second applied force 2123C (e.g., translation, -Z axis) and thereby adjust a position of electrode 2122C along the Z-axis. In some embodiments, electrode assembly 2160C may include first and second securements 2130C, 2132C coupled to ends of an actuator 2128C (e.g., teeth) of actuator assembly 2140C to secure (fix) actuator 2128C in place to counteract first applied force 2147C and transfer it into second applied force 2123C. In some embodiments, as shown in FIG. 21C, teeth of actuator 2128C may be oriented (e.g., sloped) to increase along a direction of first applied force 2147C (e.g., increase along -X axis) and extend toward a desired electrode 2122C direction of travel (e.g., -Z axis).

[0304] As shown in FIG. 21D, electrode assembly 2160D includes an electrode 2122D (e.g., an anode) configured to receive a first applied force 2147D (e.g., translation, +X axis (a “pull”)) and an actuator assembly 2140D (e.g., elevator mechanism) configured to transfer first applied force 2147D to a second applied force 2123D (e.g., translation, -Z axis) and thereby adjust a position of electrode 2122D along the Z-axis. In some embodiments, electrode assembly 2160D may include first and second securements 2130D, 2132D coupled to ends of an actuator 2128D (e.g., teeth) of actuator assembly 2140D to secure (fix) actuator 2128D in place to counteract first applied force 2147D and transfer it into second applied force 2123D. In some embodiments, as shown in FIG. 2 ID, teeth of actuator 2128D may be oriented (e.g., sloped) to increase along a direction of first applied force 2147D (e.g., increase along +X axis) and extend toward a desired electrode 2122D direction of travel (e.g., -Z axis).

[0305] In one embodiment, electrodes 2122A-2122D function as a cathode (e.g., electrode 2122A, electrode 2122B). In another embodiment, electrodes 2122A-2122D function as an anode (e.g., electrode 2122C, electrode 2122D). In terms of arrangement, in some embodiments, electrodes 2122A- 2122D are positioned above the other electrode in the gas discharge chamber (e.g., electrode 2122A, electrode 2122B). In other embodiments, electrodes 2122A-2122D are is positioned below and aligned with another electrode in the gas discharge chamber (e.g., electrode 2122C, electrode 2122D). Electrode assemblies 2160A-2160D with actuator assemblies 2140A-2140D may be applied to the various embodiments detailed in FIGS. 3-19. Non-limiting examples include the integration of actuator assemblies 2140A-2140B with actuator assembly 1040 in FIGS. 10 and 11, actuator assembly 1040' in FIG. 12, and / or actuator assembly 1040" in FIG. 13, and the integration of actuator assemblies 2140C- 2140D with anode assembly 1030 in FIGS. 10 and 11 and / or actuator 338 in FIG. 3.Example Computing System

[0306] FIG. 22 illustrates computing system 2200, according to an example embodiment. Computing system 2200 may be configured to implement one or more of the above described embodiments, or portions thereof, as computer-readable code. For example, the methods, processes, flow diagrams, and / or systems described herein may be implemented by computing system 2200. Although computing system 2200 is shown in FIG. 22 as a stand-alone apparatus and / or system, embodiments of this disclosure may be used with other apparatuses, systems, and / or methods, for example, elements in FIGS. 1-21D, e.g., lithography system 100, light source 110, pulsed light source 210, gas discharge2023P00384W001 65 chamber 300, gas discharge chamber 400, gas discharge chamber 400', gas discharge chamber 400", gas discharge chamber 400"', flow control assembly 440, flow control assembly 440', flow control assembly 440", preionization tube 470', flow diagram 900, gas discharge chamber 1000, actuator assembly 1040, actuator assembly 1040', actuator assembly 1040", electrode assembly 1160, flow diagram 1400, gas discharge chamber 1500, cathode assembly 1520, cathode assembly 1520', cathode assembly 1520", cathode assembly 1520'", cathode assembly 1520"", flow diagram 2000, electrode assembly 2160A, electrode assembly 2160B, electrode assembly 2160C, electrode assembly 2160D, and / or any suitable metrology / inspection systems.

[0307] Various embodiments of the disclosure may be implemented using one or more computing devices, such as computing system 2200 shown in FIG. 22, by software, firmware, hardware, or a combination thereof. Various embodiments are described herein in terms of example computing system 2200. One or more computing systems 2200 may be used, for example, to implement any of the embodiments described herein, as well as combinations and sub -combinations thereof. Cloud implementations may include one or more of example computing system 2200 operating locally or distributed across one or more server sites.

[0308] As shown in FIG. 22, computing system 2200 may include processor 2202, controller 2204, main memory 2206, communication infrastructure 2208 (e.g., a bus), user input / output (I / O) interface(s) 2210, user I / O device(s) 2212, secondary memory 2220, communications interface 2234, and / or remote device(s) 2238. Computing system 2200 may include one or more processors (also called central processing units, or CPUs), such as processor 2202. Processor 2202 may be a special purpose processor or a general purpose processor. Processor 2202 may be connected to communication infrastructure 2208 (e.g., a bus, a network). Processor 2202 may include a CPU, a graphics processing unit (GPU), an accelerated processing unit (APU), an application-specific integrated circuit (ASIC), a field- programmable gate array (FPGA), a digital signal processor (DSP), a microprocessor, other similar general purpose or specialized processing units, or a combination thereof. In some embodiments, processor 2202 may include a GPU that is a specialized electronic circuit designed to process mathematically intensive applications. For example, the GPU may have a parallel structure that is efficient for parallel processing of large blocks of data, such as mathematically intensive data common to computer graphics applications, images, videos, etc.

[0309] Computing system 2200 may also include a controller 2204. Controller 2204 may include functionalities to control data access to main memory 2206 and secondary memory 2220. In some embodiments, controller 2204 may be external to processor 2202, for example, as shown in FIG. 22. In some embodiments, controller 2204 may be directly part of processor 2202. Controller 2204 may include a microcontroller or microcontroller unit (MCU).

[0310] Computing system 2200 may also include a main memory 2206. Main memory 2206 may include volatile memory (e.g., random-access memory (RAM)) and / or non-volatile memory (e.g., readonly memory (ROM), non-volatile RAM (NVRAM), flash). Main memory 2206 may include one or2023P00384W001 66 more levels of cache and be divided into channels. Main memory 2206 may have stored therein control logic (e.g., computer software) and / or data.

[0311] Computing system 2200 may also include user I / O interface(s) 2210 coupled to user I / O device(s) 2212. Computing system 2200 may also include user I / O device(s) 2212, such as monitors, keyboards, pointing devices, etc., which may communicate with communication infrastructure 2208 through user I / O interface(s) 2210.

[0312] Computing system 2200 may also include one or more secondary storage devices or memory 2220. Secondary memory 2220 may include, for example, a hard disk drive 2222 and / or a removable storage device or drive 2224. Removable storage drive 2224 may include a floppy disk drive, a magnetic tape drive, a compact disk drive, an optical storage device, a tape backup device, a flash memory, and / or any other storage device / drive.

[0313] Removable storage drive 2224 may interact with a first removable storage unit 2226. First removable storage unit 2226 may include a computer usable or readable storage device having stored thereon control logic (e.g., computer software) and / or data. First removable storage unit 2226 may be a floppy disk, a magnetic tape drive, a compact disk drive, a DVD, an optical storage device, a tape backup device, a flash memory, and / or any other computer data storage device. Removable storage drive 2224 may read from and / or write to first removable storage unit 2226.

[0314] Secondary memory 2220 may include other means, devices, components, instrumentalities, or other approaches for allowing computer programs, other instructions, and / or data to be accessed by computing system 2200. Such means, devices, components, instrumentalities, or other approaches may include, for example, a second removable storage unit 2232 and an interface 2230. Examples of the second removable storage unit 2232 and the interface 2230 may include a program cartridge and cartridge interface (e.g., such as that found in video game devices), a removable memory chip (e.g., such as an EPROM or PROM) and associated socket, a memory stick and USB port, a memory card and associated memory card slot, and / or any other removable storage unit and associated interface that allow software and / or data to be transferred from the second removable storage unit 2232 to computing system 2200.

[0315] Computing system 2200 may further include a communications or network interface 2234. Communications interface 2234 may enable computing system 2200 to communicate and interact with any combination of external devices, external networks, external entities, etc. (referenced individually and collectively by reference number 2238). For example, communications interface 2234 may allow computing system 2200 to communicate with external or remote devices 2238 over communications path 2236, which may be wired, wireless, or a combination thereof, and which may include any combination of LANs, WANs, the Internet, etc. Control logic and / or data may be transmitted to and from computing system 2200 via communications path 2236. Communications interface 2234 may include a modem, a communication port, a PCMCIA slot and card, or the like. Software and / or data may be transferred via communications interface 2234 in the form of signals, which may be electronic,2023P00384W001 67 electromagnetic, optical, or other signals capable of being transmitted and received by communications interface 2234. The signals may be provided to communications interface 2234 via communications path 2236 (e.g., wired, wireless, etc.).

[0316] Computing system 2200 may also include any computing device, for example, a laptop or notebook computer, a desktop workstation, a netbook, a tablet, a smart phone, a smart watch or other wearable device, a personal digital assistant (PDA), an Intemet-of-Things (loT) device, an embedded system, or any combination thereof.

[0317] Computing system 2200 may include a user device or server, accessing or hosting any applications and / or data through any delivery paradigm, including, but not limited to, remote or distributed cloud computing solutions; local or on-premises software (“on-premise” cloud-based solutions); “as a service” models (e.g., content as a service (CaaS), digital content as a service (DCaaS), software as a service (SaaS), managed software as a service (MSaaS), platform as a service (PaaS), desktop as a service (DaaS), framework as a service (FaaS), backend as a service (BaaS), mobile backend as a service (MBaaS), infrastructure as a service (laaS), etc.); and / or a hybrid model including any combination of the foregoing examples or other services or delivery paradigms.

[0318] Any applicable data structures, file formats, and schemas in computing system 2200 may be derived from standard programming languages, including, but not limited to, C, C++, Python, Perl, JavaScript Object Notation (JSON), Extensible Markup Language (XML), Yet Another Markup Language (Y AML), Extensible Hypertext Markup Language (XHTML), Wireless Markup Language (WML), MessagePack, XML Customer Interface Language (XUL), or any other functionally similar representations alone or in combination. Alternatively, proprietary data structures, formats or schemas may be used, either exclusively or in combination with known or open standards.

[0319] In some embodiments, a tangible, non-transitory apparatus or article of manufacture comprising a tangible, non-transitory computer useable or readable medium having control logic (software) stored thereon may also be referred to herein as a computer program product or program storage device. This may include, but is not limited to, computing system 2200, main memory 2206, secondary memory 2220, first removable storage unit 2226, and second removable storage unit 2232, as well as tangible articles of manufacture embodying any combination of the foregoing. Such control logic, when executed by one or more data processing devices (e.g., such as computing system 2200), may cause such data processing devices to operate as described herein.

[0320] Based on the teachings contained in this disclosure, it will be apparent to persons skilled in the relevant art(s) how to make and use embodiments of this disclosure using data processing devices, computing systems, and / or computing architectures other than those described herein (e.g., shown in FIG. 22). In particular, embodiments may operate with software, hardware, and / or operating system implementations other than those described herein.

[0321] Although specific reference may be made in the present disclosure to the use of the apparatus, system, and / or lithographic apparatus in the manufacture of ICs, it should be understood that such an2023P00384W001 68 apparatus, system, and / or lithographic apparatus described herein may have other possible applications, for example, such as in the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, LCD panels, thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “reticle,” “wafer,” or “die” herein may be considered as synonymous with the more general terms “mask,” “substrate,” or “target portion”, respectively.

[0322] The term “substrate” as used herein indicates a material onto which material layers are added. In some embodiments, the substrate itself may be patterned and materials added on top of it may also be patterned, or may remain without patterning. The substrate referred to herein may be processed, before or after exposure, for example, in a track unit (e.g., a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology unit, and / or an inspection unit. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example, to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers.

[0323] 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 disclosure is to be interpreted by those skilled in relevant art(s) in light of the teachings herein.

[0324] The above examples are illustrative, but not limiting, of the embodiments of this disclosure. Other suitable modifications and adaptations of the variety of conditions and parameters normally encountered in the field, and which would be apparent to those skilled in the relevant art(s), are within the spirit and scope of the disclosure.

[0325] While specific embodiments have been described above, it will be appreciated that the embodiments may be practiced otherwise than as described. The description is not intended to limit the scope of the claims.

[0326] The present disclosure may also be described in accordance with the following clauses:1. A light source comprising: a chamber configured to house a gas discharge medium; a first electrode having a first discharge surface; a second electrode opposite the first electrode having a second discharge surface, wherein the second discharge surface is spaced apart from the first discharge surface by a discharge gap; and an actuator coupled to the first electrode and configured to move with the first discharge surface, wherein the first and second electrodes are configured to excite the gas discharge medium and generate a light beam.2. The light source of clause 1, wherein the actuator comprises a flow control surface adjacent the first discharge surface and configured to maintain flow between the flow control surface and the first discharge surface.2023P00384W001 693. The light source of clause 2, wherein the flow control surface is configured to maintain laminar flow between the discharge gap.4. The light source of clause 2 or clause 3, wherein the flow control surface comprises an overhang.5. The light source of clause 4, wherein the overhang comprises a fairing adjacent the first discharge surface.6. The light source of any one of clauses 1 to 5, wherein the flow control surface comprises a preionization tube.7. The light source of clause 6, wherein the preionization tube comprises a surface having a teardrop shape.8. The light source of any one of clauses 1 to 7, wherein the actuator is configured to be parallel with the first discharge surface.9. The light source of any one of clauses 1 to 8, further comprising a controller coupled to the actuator and configured to adjust a position of the actuator based on a measured parameter of the first electrode.10. The light source of clause 9, wherein the measured parameter comprises an erosion rate of the first electrode overtime.11. The light source of clause 9 or clause 10, wherein the controller is configured to adjust the actuator continuously over time.12. The light source of any one of clauses 9 to 11, wherein the controller is configured to adjust the actuator based on a first predetermined rate of erosion of the first electrode and a second predetermined rate of erosion of the second electrode.13. The light source of any one of clauses 1 to 12, wherein the actuator is configured to compensate for erosion of the first electrode over time to increase a lifetime of the light source.14. The light source of clause 4, wherein the actuator comprises a gear coupled to a motor and the overhang.15. The light source of clause 14, wherein the gear is configured to adjust the overhang to be flush with the first discharge surface based on a gear ratio.16. The light source of clause 15, wherein the gear ratio is based on an erosion rate of the first electrode.17. The light source of clause 4, wherein the actuator comprises a spring coupled to the overhang and configured to provide a restoring force to the overhang such that the overhang is flush with the first discharge surface.18. The light source of clause 17, further comprising a controller coupled to the actuator and configured to adjust a tension of the spring to adjust a position of the overhang over time.19. The light source of clause 17 or clause 18, wherein: the actuator comprises a support coupled to a motor and the overhang, and the support is configured to adjust the restoring force of the spring by a predetermined amount.20. The light source of clause 19, wherein the predetermined amount is based on an erosion rate of the first electrode over time.2023P00384W001 7021. The light source of any one of clauses 1 to 20, further comprising a second actuator coupled to the second electrode and configured to adjust a position of the second discharge surface to maintain the discharge gap.22. The light source of clause 21, wherein the second actuator is coupled to the actuator.23. The light source of clause 22, further comprising a controller coupled to the actuator and the second actuator, the controller configured to: adjust a position of the actuator based on a measured parameter of the first electrode, and simultaneously adjust the second actuator to maintain the discharge gap based on the measured parameter of the first electrode.24. A method of controlling operation of a light source, the light source comprising an optical amplifier configured to output a light beam, the optical amplifier comprising a discharge chamber, a movable electrode assembly, and a movable flow control assembly, the method comprising: measuring a parameter of the optical amplifier; and adjusting a position of the movable flow control assembly based on the measured parameter to reduce errors in the light beam.25. The method of clause 24, wherein the adjusting the position of the movable flow control assembly comprises adjusting a position of one or more flow control surfaces with one or more actuators based on the measured parameter.26. The method of clause 25, wherein the adjusting the position of the one or more flow control surfaces comprises maintaining flow between the one or more flow control surfaces and a first discharge surface of the movable electrode assembly.27. The method of clause 26, wherein the maintaining flow between the one or more flow control surfaces and the first discharge surface comprises maintaining laminar flow.28. The method of clause 25, wherein the adjusting the position of the one or more flow control surfaces with the one or more actuators comprises adjusting the position of the one or more flow control surfaces such that the one or more flow control surfaces is flush with a first discharge surface of the movable electrode assembly.29. The method of clause 28, wherein the adjusting the position of the one or more flow control surfaces such that the one or more flow control surfaces is flush with the first discharge surface comprises adjusting the position of the one or more flow control surfaces periodically or continuously overtime.30. The method of clause 25, wherein the one or more flow control surfaces comprises an overhang, a preionization tube, or a combination thereof.31. The method of any one of clauses 24 to 30, wherein the measuring the parameter comprises measuring a parameter of the moveable electrode assembly.32. The method of clause 31, wherein the measuring the parameter comprises measuring an erosion rate of a first electrode of the movable electrode assembly.2023P00384W001 7133. The method of clause 27, further comprising adjusting a discharge gap between a first electrode and a second electrode of the movable electrode assembly based on the measured parameter.34. The method of clause 27, wherein the method is configured to compensate for erosion of the first electrode over time to increase a lifetime of the light source.35. A light source comprising: a chamber configured to house a gas discharge medium; a first electrode having a first discharge surface; a second electrode, disposed opposite of the first electrode, having a second discharge surface, wherein the second discharge surface is spaced apart from the first discharge surface by a discharge gap; and an actuator coupled to the first electrode and configured to move the first discharge surface to maintain the discharge gap, wherein the first and second electrodes are configured to excite the gas discharge medium and generate a light beam.36. The light source of clause 35, wherein the actuator is configured to maintain flow of the gas discharge medium between the first and second discharge surfaces.37. The light source of clause 35 or clause 36, wherein the actuator is configured to compensate for erosion of the first electrode overtime.38. The light source of any one of clauses 35 to 37, wherein the actuator comprises a support coupled to a motor and configured to adjust a position of the first discharge surface.39. The light source of clause 38, wherein the support is configured to adjust the position of the first discharge surface based on a predetermined ratio.40. The light source of clause 39, further comprising a conductive flexure, wherein the conductive flexure is positioned between the first electrode and the support.41. The light source of clause 40, wherein the conductive flexure is electrically coupled to the first electrode and is electrically coupled to the support.42. The light source of clause 39 or clause 40, wherein the support comprises a control surface and the predetermined ratio is based on an opening angle of the control surface.43. The light source of any one of clauses 39 to 42, wherein the predetermined ratio is based on an erosion rate of the first electrode.44. The light source of any one of clauses 39 to 43, wherein the predetermined ratio is based on a first rate of erosion of the first electrode and a second rate of erosion of the second electrode.45. The light source of any one of clauses 35 to 44, wherein the actuator comprises a transducer coupled to the first electrode and configured to provide a restoring force to the first electrode to move the first discharge surface towards the second discharge surface.46. The light source of clause 45, wherein the transducer comprises an elevator mechanism that is pre- loaded, and the elevator mechanism comprises one or more teeth on the first electrode and a support with one or more grooves coupled to the one or more teeth.2023P00384W001 7247. The light source of clause 46, wherein the elevator mechanism is pre-loaded such that as the support moves relative to the first electrode, the restoring force is applied to the first electrode and the first discharge surface protrudes towards the second discharge surface.48. The light source of any one of clauses 35 to 47, wherein: the actuator comprises a support coupled to a motor, the support is configured to adjust a restoring force of a transducer coupled to the first electrode by a predetermined amount, and the predetermined amount is based on an erosion rate of the first electrode overtime.49. The light source of any one of clauses 35 to 48, further comprising a second actuator coupled to the second electrode and configured to adjust a position of the second discharge surface to maintain the discharge gap.50. The light source of clause 49, wherein the second actuator is coupled to the actuator.51. The light source of clause 50, further comprising a controller coupled to the actuator and the second actuator, the controller configured to perform operations comprising: adjusting a position of the actuator based on a parameter of the first electrode, and simultaneously adjusting the second actuator to maintain the discharge gap based on the parameter of the first electrode.52. A method of controlling operation of a light source, the light source comprising an optical amplifier configured to output a light beam, the optical amplifier comprising a discharge chamber and a movable electrode assembly, the method comprising: determining a parameter of the optical amplifier; and adjusting a position of the movable electrode assembly based on the parameter to reduce errors in the light beam.53. The method of clause 52, wherein the adjusting the position of the movable electrode assembly comprises adjusting a position of one or more electrodes with one or more actuators based on the parameter.54. The method of clause 53, wherein the adjusting the position of the one or more electrodes with the one or more actuators comprises adjusting a first position of the first discharge surface.55. The method of clause 54, wherein the adjusting the position of the one or more electrodes with the one or more actuators further comprises simultaneously adjusting a second position of the second discharge surface.56. The method of any one of clauses 52 to 55, further comprising dynamically extending a conductive flexure to maintain electrical connection during adjusting the position of the movable electrode assembly.57. A light source comprising: a chamber configured to house a gas discharge medium;2023P00384W001 73 a first electrode assembly having a first discharge surface, wherein the first electrode assembly comprises: a first electrode coupled to a power source; a rod having a proximal end and a distal end, wherein the rod extends longitudinally through a portion of the first electrode; and a tip portion coupled to the distal end of the rod and comprising the first discharge surface; and a second electrode, disposed opposite of the first electrode assembly, having a second discharge surface, wherein the second discharge surface is spaced apart from the first discharge surface by a discharge gap, wherein the rod is configured to adjust a position of the tip portion to maintain the discharge gap, and wherein the first and second electrodes are configured to excite the gas discharge medium and to generate a light beam.58. The light source of clause 57, wherein the rod extends through a longitudinal bore of the first electrode.59. The light source of clause 58, wherein the rod is configured to translate along the longitudinal bore and, when the rod is translated, thereby adjust a position of the first discharge surface of the tip portion to maintain the discharge gap.60. The light source of clause 58 or clause 59, wherein the rod comprises a screw configured to interlock with the tip portion and, when the rod is rotated, thereby adjust a position of the first discharge surface of the tip portion to maintain the discharge gap.61. The light source of any one of clauses 57 to 60, wherein the first electrode assembly further comprises a gasket between the first electrode and the rod, wherein the gasket is configured to maintain a pressure of the chamber.62. The light source of any one of clauses 57 to 61, wherein the first electrode assembly further comprises a conductive flexure disposed between the first electrode and the tip portion, wherein the conductive flexure is configured to maintain electrical connection between the first electrode and the tip portion and configured to apply an upward restoring force to the rod.63. The light source of clause 62, wherein the first electrode assembly further comprises one or more screws coupled to the conductive flexure and configured to adjust a position of the conductive flexure.64. The light source of any one of clauses 57 to 63, wherein the first electrode assembly further comprises a plug coupled to the proximal end of the rod and configured to adjust a position of the first discharge surface of the tip portion.65. The light source of clause 64, wherein the plug comprises a precision length tip configured to adjust a length of the rod and thereby adjust a position of the first discharge surface of the tip portion to maintain the discharge gap.2023P00384W001 7466. The light source of any one of clauses 57 to 65, wherein the first electrode assembly further comprises an actuator coupled to the proximal end of the rod and configured to adjust a position of the first discharge surface of the tip portion to maintain the discharge gap.67. The light source of clause 66, wherein the actuator is electrically insulated from the first electrode and configured to adjust the position of the first discharge surface of the tip portion based on a predetermined ratio.68. An electrode assembly for a light source, the electrode assembly comprising: an electrode coupled to a power source; a rod extending longitudinally through a portion of the electrode; and a tip portion coupled to the rod and comprising a discharge surface, wherein the rod is configured to adjust a position of the discharge surface.69. The electrode assembly of clause 68, further comprising a second electrode, disposed opposite of the tip portion, having a second discharge surface, wherein the second discharge surface is spaced apart from the discharge surface by a discharge gap.70. The electrode assembly of clause 68 or clause 69, wherein the rod is configured to extend through a longitudinal bore of the electrode.71. The electrode assembly of clause 70, wherein the rod is configured to translate along the longitudinal bore and, when the rod is translated, thereby adjust the position of the discharge surface of the tip portion.72. The electrode assembly of clause 70 or clause 71, wherein the rod comprises a screw configured to interlock with the tip portion and, when the rod is rotated, thereby adjust the position of the discharge surface of the tip portion.73. The electrode assembly of any one of clauses 68 to 72, further comprising a conductive flexure disposed between the electrode and the tip portion, wherein the conductive flexure is configured to maintain electrical connection between the electrode and the tip portion and configured to apply an upward restoring force to the rod.74. The electrode assembly of any one of clauses 68 to 73, further comprising an actuator coupled to the rod and configured to adjust the position of the discharge surface of the tip portion.75. A method of controlling operation of a light source, the light source comprising a chamber configured to house a gas discharge medium, a first electrode assembly having a first discharge surface, and a second electrode having a second discharge surface, wherein the second discharge surface is spaced apart from the first discharge surface by a discharge gap, wherein the first and second electrodes are configured to excite the gas discharge medium and generate a light beam, the method comprising: determining a number of pulses generated by the light source; and adjusting a position of the first discharge surface based on the number of pulses to adjust the discharge gap-2023P00384W001 7576. The method of clause 75, wherein the adjusting the position of the first discharge surface comprises translating a rod of the first electrode assembly along a longitudinal bore of a first electrode of the first electrode assembly.77. The method of clause 75 or clause 76, wherein the adjusting the position of the first discharge surface comprises rotating a rod of the first electrode assembly within a longitudinal bore of a first electrode of the first electrode assembly.78. The method of any one of clauses 75 to 77, wherein the adjusting the position of the first discharge surface comprises inserting a plug into a longitudinal bore of a first electrode of the first electrode assembly, the plug comprising a precision length tip configured to adjust a length of a rod of the first electrode assembly.79. The method of any one of clauses 75 to 77, wherein the adjusting the position of the first discharge surface comprises adjusting a rod of the first electrode assembly with an actuator based on a predetermined ratio.80. The method of clause 79, wherein the predetermined ratio is based on an erosion rate of the first electrode.81. The method of clause 79 or clause 80, wherein the predetermined ratio is based on a first rate of erosion of the first electrode and a second rate of erosion of the second electrode.82. The method of any one of clauses 75 to 81, further comprising adjusting a position of the second discharge surface based on the number of pulses to adjust the discharge gap.

[0327] 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 the specific embodiments 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 embodiments, without undue experimentation, 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 embodiments, based on the teaching and guidance presented herein.

[0328] It is to be appreciated 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 may set forth one or more but not all example embodiments as contemplated by the inventor(s), and thus, are not intended to limit the embodiments and the appended claims in any way. The breadth and scope of the protected subject matter should not be limited by any of the above -de scribed example embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims

2023P00384W001 76CLAIMS1. A light source comprising: a chamber configured to house a gas discharge medium; a first electrode having a first discharge surface; a second electrode opposite the first electrode having a second discharge surface, wherein the second discharge surface is spaced apart from the first discharge surface by a discharge gap; and an actuator coupled to the first electrode and configured to move with the first discharge surface, wherein the first and second electrodes are configured to excite the gas discharge medium and generate a light beam.

2. The light source of claim 1, wherein the actuator comprises a flow control surface adjacent the first discharge surface and configured to maintain flow between the flow control surface and the first discharge surface.

3. The light source of claim 2, wherein the flow control surface comprises an overhang.

4. The light source of claim 3, wherein the overhang comprises a fairing adjacent the first discharge surface.

5. The light source of claim 3, wherein the actuator comprises a gear coupled to a motor and the overhang.

6. The light source of claim 5, wherein the gear is configured to adjust the overhang to be flush with the first discharge surface based on a gear ratio.

7. The light source of claim 6, wherein the gear ratio is based on an erosion rate of the first electrode.

8. The light source of claim 3, wherein the actuator comprises a spring coupled to the overhang and configured to provide a restoring force to the overhang such that the overhang is flush with the first discharge surface.

9. The light source of claim 8, further comprising a controller coupled to the actuator and configured to adjust a tension of the spring to adjust a position of the overhang over time.2023P00384W001 7710. The light source of claim 1, further comprising a controller coupled to the actuator and configured to adjust a position of the actuator based on a measured parameter of the first electrode.

11. The light source of claim 10, wherein the controller is configured to adjust the actuator based on a first predetermined rate of erosion of the first electrode and a second predetermined rate of erosion of the second electrode.

12. The light source of claim 1, further comprising a second actuator coupled to the second electrode and configured to adjust a position of the second discharge surface to maintain the discharge gap-13. A method of controlling operation of a light source, the light source comprising an optical amplifier configured to output a light beam, the optical amplifier comprising a discharge chamber, a movable electrode assembly, and a movable flow control assembly, the method comprising: measuring a parameter of the optical amplifier; and adjusting a position of the movable flow control assembly based on the measured parameter to reduce errors in the light beam.

14. The method of claim 13, wherein the adjusting the position of the movable flow control assembly comprises adjusting a position of one or more flow control surfaces with one or more actuators based on the measured parameter.

15. The method of claim 14, wherein the adjusting the position of the one or more flow control surfaces comprises maintaining flow between the one or more flow control surfaces and a first discharge surface of the movable electrode assembly.

16. The method of claim 14, wherein the adjusting the position of the one or more flow control surfaces with the one or more actuators comprises adjusting the position of the one or more flow control surfaces such that the one or more flow control surfaces is flush with a first discharge surface of the movable electrode assembly.

17. A method of controlling operation of a light source, the light source comprising a chamber configured to house a gas discharge medium, a first electrode assembly having a first discharge surface, and a second electrode having a second discharge surface, wherein the second discharge surface is spaced apart from the first discharge surface by a discharge gap, wherein the first and second electrodes are configured to excite the gas discharge medium and generate a light beam, the method comprising:2023P00384W001 78 determining a number of pulses generated by the light source; and adjusting a position of the first discharge surface based on the number of pulses to adjust the discharge gap.

18. The method of claim 17, wherein the adjusting the position of the first discharge surface comprises translating a rod of the first electrode assembly along a longitudinal bore of a first electrode of the first electrode assembly.

19. The method of claim 17, wherein the adjusting the position of the first discharge surface comprises rotating a rod of the first electrode assembly within a longitudinal bore of a first electrode of the first electrode assembly.

20. The method of claim 17, wherein the adjusting the position of the first discharge surface comprises inserting a plug into a longitudinal bore of a first electrode of the first electrode assembly, the plug comprising a precision length tip configured to adjust a length of a rod of the first electrode assembly.

Images