Laser chamber playonizer with acoustic scattering surface

Abstract

The apparatus generates laser radiation from a discharge in a discharge chamber, wherein the discharge generates sound waves that, when reflected back to the source, will interfere with the operation of the apparatus at a specific repetition rate, and the surface of a pre-onizer tube positioned within the discharge chamber is provided with acoustic scattering features that scatter sound waves that collide with the surface of the pre-onizer tube. The pre-onizer tube may also be configured to have a cross-section that exhibits a surface at an angle to the region where the discharge is generated.

Description

Technical Field

[0001] (Cross - reference to Related Applications)

[0001] This application claims priority to U.S. Application No. 63 / 455,476, filed on March 29, 2023, and U.S. Application No. 63 / 560,973, filed on March 4, 2024, both entitled "LASER CHAMBER PREIONIZER HAVING ACOUSTIC SCATTERING SURFACE", the entire contents of which are incorporated herein by reference.

[0002]

[0002] The disclosed subject matter relates to a laser discharge chamber in which a discharge in a discharge region generates laser radiation and also generates acoustic disturbances that can be undesirably reflected back into the discharge region.

Background Art

[0003]

[0003] Photolithography is a process of patterning a semiconductor circuit on a substrate such as a silicon wafer. A photolithography radiation source provides deep ultraviolet (DUV) radiation (wavelengths in the range of about 100 nanometers (nm) to about 400 nm) for exposing a photoresist on the wafer. The radiation source is often a laser source and the radiation is often a pulsed laser beam. The radiation beam passes through a beam delivery unit, then through a reticle or mask, and then is projected onto a silicon wafer coated with a photoresist. In this way, the chip design is patterned on the photoresist, and then the photoresist is etched and cleaned.

[0004]

[0004] Many systems that generate a laser beam (such as a laser generator) or use a laser beam (such as a photolithography system) have an optical train, which includes one or more optical components (such as mirrors, gratings, prisms, optical switches, filters, etc.). The optical components of the optical train reflect, process, filter, modify, focus, and magnify the laser beam, either entirely or partially, to obtain one or more desired laser beam outputs.

[0005]

[0005] In such systems, the laser beam is generated by causing a discharge in the inter-electrode discharge region of one or more laser discharge chambers. One challenge in designing and using these systems is that the discharge that generates the laser radiation also generates strong sound waves within the discharge region. These sound waves create gas density modulation as they propagate within the laser discharge chamber. Surfaces within the laser discharge chamber can reflect these sound waves back into the discharge region, potentially negatively impacting the laser's performance. Specifically, these reflected waves can result in round-trip time-of-flight resonance depending on the pulse delay or discharge repetition rate in which the laser system operates.

[0006]

[0006] It would be advantageous to mitigate the adverse effects of these acoustic disturbances. It is in this context that the subject matter of this disclosure arises. [Overview of the project]

[0007]

[0007] The following provides a brief overview of one or more embodiments to facilitate a basic understanding of the subject matter of this disclosure. This overview is not intended to be an extensive overview of all possible embodiments, nor to identify any element of any embodiment as key or significant, nor to describe in detail the scope of any or all embodiments. Its sole purpose is to provide a streamlined explanation of some concepts relating to one or more embodiments as a prelude to more detailed descriptions to be presented later.

[0008]

[0008] According to one aspect of one embodiment, a pre-onizer for a laser system is disclosed, which comprises a tube having an outer surface and a tube wall, configured as a substantially cylindrical hollow tube extending axially in a first direction, wherein at least a portion of the outer surface is provided with a plurality of acoustic scattering features, and an electrode positioned at least partially inside the tube.

[0009]

[0009] The tube may be made of a dielectric material. The acoustic scattering feature portion may have a penetration depth into the tube wall that is greater than half the nominal thickness of the tube wall.

[0010]

[0010] When the laser system is operating at 6 kHz, the acoustic scattering feature may have a penetration depth of at least 0.063 inches into the tube wall.

[0011]

[0011] The laser system may be configured to generate a discharge in a discharge region having a height H and a width W, and the penetration depth of the acoustic scattering feature portion into the tube wall may be in the range of 1 / 4H to 1 / 4W, including the values ​​at both ends.

[0012]

[0012] The laser system may be configured to generate a discharge in the discharge region, and the acoustic scattering feature may be provided on at least a portion of the outer surface facing the discharge area. The acoustic scattering feature may be provided on substantially the entire outer surface.

[0013]

[0013] The acoustic scattering feature portion can be manufactured by forming the acoustic scattering feature portion on at least a part of the outer surface.

[0014]

[0014] Multiple acoustic scattering feature portions may be arranged in an array provided on at least a portion of the outer surface. The array may be non-periodic.

[0015]

[0015] The closest of the multiple acoustic scattering features may be spaced apart by a distance of 0.01 inches to 0.5 inches between their edges. The acoustic scattering features may be arranged to have a density ranging from 3 acoustic scattering features per square inch to 100 acoustic scattering features per square inch. The multiple acoustic scattering features may each have an area ranging from 0.1 square inches to 0.5 square inches. The multiple acoustic scattering features may have a total outer surface coverage ranging from 10 percent to 100 percent.

[0016]

[0016] According to another embodiment of one embodiment, a pre-onizer for an excimer laser is disclosed, the pre-onizer comprising: a tube body having a tube wall, the tube wall having an outer surface; a plurality of baffles provided on an acoustic scattering surface of the outer surface, the acoustic scattering surface extending longitudinally along the length of the tube body, and each baffle being positioned and sized to scatter acoustic reflections from the acoustic scattering surface; and electrodes positioned at least partially within the tube body.

[0017]

[0017] The tube wall may be made of a dielectric material. The baffle may have a penetration depth into the tube wall that is greater than half the thickness of the tube wall. The excimer laser may operate at 6 kHz, in which case the baffle has a penetration depth into the tube wall of at least 0.063 inches.

[0018]

[0018] The excimer laser may be configured to generate a discharge in a discharge region having a height H and a width W, and the depth of the baffle's penetration into the tube wall may be in the range of 1 / 4H to 1 / 4L, including the values ​​at both ends.

[0019]

[0019] The excimer laser may be configured to generate a discharge in the discharge region, and the acoustic scattering surface may include a portion of the external surface facing the discharge area. The acoustic scattering surface may include substantially all of the external surface.

[0020]

[0020] The acoustic scattering surface can be created by forming a baffle on the tube wall.

[0021]

[0021] The acoustic scattering surface may comprise an array of baffles provided on its outer surface. The array may be non-periodic. The baffles may be arranged to have a density ranging from 3 baffles per square inch to 100 baffles per square inch. The baffles may include baffles each having an area ranging from 0.1 square inches to 0.5 square inches.

[0022]

[0022] The baffles may have an edge spacing between the nearest adjacent baffles ranging from 0.01 inches to 0.5 inches. Multiple baffles may cover 10 percent to 100 percent of the outer surface.

[0023]

[0023] According to another aspect of one embodiment, a discharge chamber for a laser system is disclosed, the discharge chamber comprising: a first electrode having a first electrode discharge surface; a second electrode having a second electrode discharge surface, wherein the first electrode discharge surface is positioned facing and spaced away from the second electrode discharge surface so as to define a discharge gap; and a pre-onizer including a pre-onizer tube extending laterally adjacent to the first electrode, wherein the surface of the pre-onizer tube facing the discharge gap is provided with a plurality of acoustic scattering features sized and positioned to scatter sound waves from the discharge gap.

[0024]

[0024] The pre-onizer tube may comprise a dielectric material. The acoustic scattering feature may have a penetration depth into the pre-onizer tube facing the discharge gap, and this penetration depth is greater than half the nominal thickness of the pre-onizer tube wall. The discharge chamber may operate at 6 kHz, and the acoustic scattering feature may have a penetration depth of at least 0.063 inches into the pre-onizer tube.

[0025]

[0025] The discharge chamber may be configured to generate a discharge in a discharge region having a height H and a width W, and the penetration depth of the acoustic scattering feature portion into the plasma generator tube may be in the range of 1 / 4H to 1 / 4W, including both end values.

[0026]

[0026] The acoustic scattering surface can be produced by forming the acoustic scattering feature portion on the wall of the plasma generator tube.

[0027]

[0027] The acoustic scattering surface may include an array of acoustic scattering feature portions provided on the surface of the plasma generator tube facing the discharge gap. The array may be aperiodic.

[0028]

[0028] The respective acoustic scattering feature portions may have edges spaced from the closest acoustic scattering structure by a distance in the range of 0.01 inch to 0.5 inch. The acoustic scattering feature portions can be arranged on the surface of the plasma generator tube facing the discharge gap so as to have a density in the range of 3 acoustic scattering feature portions per square inch to 100 acoustic scattering feature portions per square inch. The plurality of acoustic scattering feature portions may include acoustic scattering feature portions each having an area in the range of 0.1 square inch to 0.5 square inch. The acoustic scattering feature portions may cover about 10 percent to 100 percent of the surface of the plasma generator tube facing the discharge gap.

[0029]

[0029] Further embodiments, features, and advantages of the subject matter of this disclosure, as well as the structures and operations of the various embodiments, will be described in detail below with reference to the accompanying drawings.

Brief Description of the Drawings

[0030]

[0030] The accompanying drawings, which are incorporated herein and form a part of this specification, illustrate the subject matter of this disclosure and, together with the description, serve to clarify the principles of the subject matter of this disclosure and further function to enable those skilled in the art to make and use the subject matter of this disclosure.

[0031] [Figure 1]

[0031] This is a schematic diagram of the overall broad concept of a photolithography system, and the scale is not accurate. [Figure 2]

[0032] Figure 1 is a schematic diagram of a broad overall concept of a lighting system that may be used in a photolithography system, and the scale is not precise. [Figure 3]

[0033] Figure 2 is a cross-sectional view of a discharge chamber that may be used in the lighting system shown, and the scale is not accurate. [Figure 4]

[0034] Figure 3 is a cross-sectional view of a portion of the discharge chamber, and the scale is not accurate. [Figure 5]

[0035] Figure 3 is a perspective view of the arrangement of components within the discharge chamber, and the scale is not accurate. [Figure 6A]

[0036] This is a cross-sectional view of a portion of the discharge length in the play-onizer system and discharge area. [Figure 6B]

[0037] Figure 6A is a cross-sectional view of the playonizer system and discharge. [Figure 7]

[0038] This is a diagram of a portion of the wall of a playonizer tube in a playonizer system according to one embodiment of the system, and the scale is not accurate. [Figure 8]

[0039] This is a projection of a portion of the outer surface of a plyonizer tube wall, which is provided with an arrangement of acoustic scattering feature elements for creating an acoustic scattering surface, according to one embodiment of the present invention. [Figure 9]

[0040] This is a projection of a portion of the outer surface of a plyonizer tube wall, provided with an alternative arrangement of acoustic scattering features for creating an acoustic scattering surface, according to one embodiment of the present invention. [Figure 10]

[0041] This is a side view of a pre-ionizer tube equipped with an acoustic scattering feature section according to one embodiment of one of the following. [Figure 11]

[0042] Figure 10 is a perspective view of the pre-ionizer tube. [Figures 12A-12D]

[0043] This is a side view of an example of an embodiment of the acoustic scattering feature section according to the embodiment. [Figure 13A]

[0044] This is a side cross-sectional view of a playonizer according to one embodiment of one of its parts. [Figure 13B]

[0045] Figure 13A is an end view of the playonizer. [Figure 14A]

[0046] This is a side cross-sectional view of a pre-ionizer tube according to another embodiment of one of the present inventions. [Figure 14B]

[0047] This is a side cross-sectional view of a pre-ionizer tube according to another embodiment of one of the present inventions. [Figure 14C]

[0048] This is a side cross-sectional view of a pre-ionizer tube according to another embodiment of one of the present inventions. [Figure 15]

[0049] This is a side cross-sectional view of a pre-ionizer tube according to another embodiment of one of the present inventions.

[0032]

[0050] Further features and advantages of the subject matter of this disclosure, as well as the structure and operation of various embodiments thereof, will be described in detail below with reference to the accompanying drawings. It should be noted that the scope of the subject matter of this disclosure is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Those skilled in the art will see additional embodiments based on the teachings presented herein. [Modes for carrying out the invention]

[0033]

[0051] Next, various embodiments will be described with reference to the drawings. Throughout this text, the same reference numerals are used to refer to the same elements. In the following description, many specific details are given for illustrative purposes to facilitate a complete understanding of one or more embodiments. However, it will be apparent that in some or all cases any of the embodiments described below can be implemented without adopting the specific design details related to that embodiment. In other cases, well-known structures and devices are shown in block diagram form to facilitate the description of one or more embodiments. This summary is not intended to be a comprehensive overview of all possible embodiments, nor is it intended to select any element of any embodiment as key or significant, nor to describe in detail the scope of any or all embodiments.

[0034]

[0052] Systems like those described herein may be beneficial in a wide range of applications and embodiments. To facilitate the explanation, a specific, non-limiting example is one such application in semiconductor photolithography. Figure 1 shows a photolithography system 100 including an illumination system 105. As will be more fully described below, the illumination system 105 includes a radiation source which generates a pulsed radiation beam 110 directed towards a photolithography exposure apparatus 115, such as a scanner, for patterning microelectronic features on a wafer 120. The wafer 120 is placed on a wafer table 125 connected to a positioner 130 which is constructed to hold the wafer 120 and configured to precisely position the wafer 120 according to specific parameters.

[0035]

[0053] The pulsed radiation beam 110 may have a wavelength in the DUV range, for example, 248 nanometers (nm) or 193 nm. The scanner 115 includes an optical arrangement 135 having, for example, one or more focusing lenses, a mask, and an objective lens arrangement. The mask is movable along one or more directions, such as along the optical axis of the pulsed radiation beam 110 or in a plane perpendicular to the optical axis. The objective lens arrangement includes a projection lens, enabling the transfer of an image from the mask to the photoresist on the wafer 120. The illumination system 105 adjusts the range of angles at which the pulsed radiation beam 110 is incident on the mask. The illumination system 105 also homogenizes (uniformizes) the intensity distribution of the pulsed radiation beam 110 across the mask.

[0036]

[0054] Among its various features, the scanner 115 may include a lithography controller 140 that controls how layers are printed on the wafer 120. The lithography controller 140 may include memory that stores information such as a process recipe that determines beam parameters, including the exposure length for the wafer 120, based on the mask used and other factors affecting exposure. During lithography, bursts of pulses from the pulsed radiation beam 110 illuminate the same area of ​​the wafer 120 to constitute the irradiation dose.

[0037]

[0055] The photolithography system 100 also preferably includes a control system 145. Generally, the control system 145 includes one or more of the following: digital electronic circuits, computer hardware, firmware, and software. The control system 145 may be centralized or may be partially or completely distributed throughout the photolithography system 100.

[0038]

[0056] Figure 2 shows a pulsed laser source that generates a pulsed laser beam as the radiation beam 110, as an example of the illumination system 105. Although Figure 2 shows a two-chamber laser system as a non-limiting example, it will be understood that the principles revealed herein are equally applicable to single-chamber laser systems or laser systems having more than two chambers. A gas discharge laser system may include, for example, a solid or gas discharge main oscillator ("MO") seed laser system 200, an amplification stage, such as a power ring amplifier ("PRA") stage 205, relay optical components 210, and a laser system output subsystem 215. The seed system 200 may include, for example, an MO chamber 220 including a pair of electrodes 222 and 224.

[0039]

[0057] The MO seed laser system 200 may also include a main oscillator output coupler ("MO OC") 230, which may have a partial reflection mirror, forming an MO discharge chamber 220 having an oscillator cavity that oscillates to form seed laser output pulses, partially defined by a reflection grating (not shown) in a line narrowing module ("LNM") 235. The MO seed laser system 200 may also include a line centering analysis module ("LAM") 240. The MO wavefront engineering box ("WEB") 245 may serve to redirect the output of the MO seed laser system 200 toward the amplification stage 205 and may include, for example, a multiprism beam expander (not shown) and an optical delay path (not shown). The beam paths through the LNM 235, MO discharge chamber 220, MO OC 230, and LAM 240 define the optical axes 237 of each of these components.

[0040]

[0058] The amplification stage 205 may include, for example, a PRA discharge chamber 250, which may also be an oscillator formed by, for example, a seed beam injection and an output coupling optical system (not shown) that may be incorporated into a PRA web 255. The beam may be redirected by a beam inverter ("BR") 260 to return through a gain medium in the PRA discharge chamber 250. The PRA web 255 may incorporate a partially reflective input / output coupler (not shown), a maximum reflection mirror for the nominal operating wavelength (e.g., around 193 nm for ArF systems), and one or more prisms. The PRA discharge chamber 250 may also include a pair of electrodes 252 and 254.

[0041]

[0059] The Bandwidth Analysis Module ("BAM") 265 receives the pulsed output laser emission beam from the PRA discharge chamber 250 and may pick off a portion of the emission beam for metrologic purposes, such as measuring the output bandwidth and pulse energy. The pulsed laser output emission beam then passes through the PRA web 255 to the optical pulse stretcher ("OPuS") 270 and an auto-shutter, in this case a composite auto-shutter metrologic module ("CASMM") 275, where a pulse energy meter may also be located. One purpose of the OPuS 270 may be, for example, to convert a single output laser pulse into a pulse train. Secondary pulses produced from the original single output pulse can be delayed relative to each other. By distributing the original laser pulse energy into a train of secondary pulses, the effective pulse length of the laser can be increased while simultaneously reducing the peak pulse intensity. Therefore, the OPuS 270 may be positioned to receive the laser beam from the PRA web 255 and direct its output to the CASMM 275.

[0042]

[0060] The beam paths passing through BR260, PA discharge chamber 250, and BAM265 define the optical axes 267 of each of these components.

[0043]

[0061] The PRA discharge chamber 250 and the MO discharge chamber 220 are configured as chambers, within which discharges between electrodes induce laser oscillating gas discharges in the laser oscillating gas, creating population inversion of high-energy molecules or excimers, such as ArF, KrF, F2, XeF, and / or XeCl, generating relatively broadband radiation. This radiation can be line-narrowed to a relatively ultra-narrowband and center wavelength selected at LNM235.

[0044]

[0062] Referring here to Figure 3, a laser discharge chamber 300 is shown which may function as, for example, a PRA discharge chamber 250 or an MO discharge chamber 220. The chamber 300 may consist of, for example, an upper chamber body 305 and a lower chamber body 310, which, when connected to each other by appropriate means, such as bolting, may function to define the interior of the chamber 315. The upper chamber body 305 and the lower chamber body 310 also define the interior vertical walls 320 of the chamber, and the lower chamber body 310 also defines the interior horizontal bottom wall 325 of the chamber.

[0045]

[0063] In this specification, including in the claims, terms such as “up,” “down,” “upper side,” “lower side,” “top,” “bottom,” “vertical,” and “horizontal” are intended to imply only relative orientation and not absolute orientation such as orientation relative to gravity unless otherwise indicated or made clear from the context.

[0046]

[0064] Housed within the chamber 315 is, for example, a gas discharge system comprising two elongated (along the X-axis extending from the plane of the figure) opposing electrodes, a cathode 330 and an anode 335, with an elongated gas discharge gap or region 340 defined between the electrodes. In response to a sufficient voltage being applied between the cathode 330 and the anode 335, a discharge occurs in the gas discharge region 340, resulting in the generation of radiation at or near the characteristic center wavelength. This radiation is optically guided along the optical axis of the output laser radiation pulse, which is roughly aligned with the longitudinal optical axis of the laser discharge chamber 300 along the X-axis (extending from the plane of the figure) as shown in the inset.

[0047]

[0065] Furthermore, an anode support bar 345 may be present inside the chamber 315, for example. The anode 335 may be electrically connected to the upper chamber body 305 through a plurality of current return sections 306, and the upper chamber body 305, together with the lower chamber body 310, is maintained at a common voltage, such as the ground voltage.

[0048]

[0066] The cathode 330 may be connected to, for example, a discharge high-voltage feedthrough assembly 350 by a high-voltage feedthrough 355 that penetrates, for example, the main insulator 360. The main insulator 360 can keep the cathode 330 electrically isolated from the upper chamber body 305. Also, within the chamber interior 315, there may be, for example, a pleyonizer 365, which may include, for example, a pleyonizer tube adjacent to the cathode 330. The pleyonizer 365 may be configured as an elongated, hollow tube made of dielectric material, positioned parallel to the discharge electrode and near the discharge region. A conductive pleyonizing electrode (typically made of copper or brass) is positioned within the tube's opening and used to create a potential difference between the pleyonizing electrode and one of the main discharge electrodes. This potential difference spreads radially across the dielectric tube, resulting in a substantially uniform emission of photons from the outer surface of the tube.

[0049]

[0067] Further information about the preionizer can be found in U.S. Patent No. 7,542,502, published on June 2, 2009, entitled "Thermal-expansion Tolerant, Preionizer Electrode for a Gas Discharge Laser".

[0050]

[0068] All patent applications, patents, and printed publications referenced herein are incorporated herein by reference in their entirety, except for any definitions, denials of subject matter, or abandonments, and to the extent that incorporated material conflicts with the express disclosure herein, in which case the language of this disclosure shall prevail.

[0051]

[0069] Furthermore, the chamber interior 315 may also contain a gas circulation system equipped with a gas circulation fan 370, which may be, for example, a substantially cylindrical cross-flow fan 370. The fan 370 contains ionized particles and debris and functions to move the gas within the chamber interior 315 in a substantially circular manner, as shown in the cross-sectional view of Figure 3, in order to remove gas depleted of F2 from the discharge region 340 between successive discharges and, consequently, to replenish the discharge region 340 with fresh gas before the next gas discharge. The gas circulation system may also include a plurality of heat exchangers 375 in a substantially circular gas flow path to remove heat added to the gas, for example, by the discharge and the operation of the fan 370.

[0052]

[0070] The gas circulation system may also have a plurality of curved baffles 380 and flow guide vanes 385, which can each serve to form a generally circular gas flow path, one exiting the discharge region 340 and heading toward the heat exchanger 375 and ultimately toward the intake of the fan 370, and the other returning from the output of the fan 370 toward the discharge region 340. The upper chamber body 305 may also have a mounted metal fluoride trap 390 that is in fluid communication with the inside of the chamber 315.

[0053]

[0071] Figure 4 is a schematic diagram further illustrating how the electrodes and adjacent components are installed within the gas discharge laser chamber. As shown in Figure 4, the anode 335 and cathode 330 are arranged opposite each other, with the elongated cathode discharge surface 332 facing the elongated discharge anode surface 337. The anode 335 is mounted on an anode support bar 345. The gas discharge region 340, which is the space defined between the elongated cathode discharge surface 332 and the elongated anode discharge surface 337, typically has a height of about 0.5 inches (in the Y-axis direction). In one example, the respective lengths L of the anode 335 and cathode (see Figure 5) may range, for example, from about 20 to 30 inches. As mentioned above, the width of the discharge region and the length of the electrodes may be modified to suit the needs of the specific application. A plyonizer 365 is also visible in Figure 4.

[0054]

[0072] Figure 5 is a perspective view of an example of the arrangement of components within the laser discharge chamber 300. As can be seen in Figure 5, the elongated cathode discharge surface 332 of the cathode 330 faces the elongated anode discharge surface 337 of the anode 335, separated by a gap that defines the discharge region 340. When a discharge occurs in the discharge region 340, the radiation generated by the discharge propagates in the direction indicated by the arrow 400. The optical axis 410 of the laser discharge chamber 300 is also shown. As shown in the figure, the optical axis 410 can be considered to extend parallel to the X-axis of the right-handed Cartesian coordinate system. The elongated cathode 330, the elongated anode 335, and the gap that defines the discharge region 340 all extend parallel to the optical axis 410. A pleyonizer 365, which also extends parallel to the optical axis 410, can also be seen in Figure 5. Figure 5 also shows the main insulator 360 with a dashed line, which also extends parallel to the optical axis 410. The anode support bar 345, which also extends parallel to the optical axis 410, can also be seen in Figure 5.

[0055]

[0073] The discharge generated in the discharge region 340 generates sound waves inside the discharge chamber 300. The sound waves generated by the discharge propagate outward from the discharge region 340, are reflected off the inner surface of the laser discharge chamber 300, and then return to the discharge region, where they distort the laser beam generated by subsequent pulses.

[0056]

[0074] One measure that can be employed to mitigate the adverse effects of these acoustic disturbances involves placing acoustic baffles on the inner surface of the discharge chamber walls. As a result, sound waves reflected by the walls do not all return to the discharge region coherently at once. Rather, the baffles randomize, or scatter, the acoustic reflections. This reduces resonant reflections because the returning waves reach different parts of the discharge region at different times, reducing their overall adverse effect on laser performance. This measure is generally effective in suppressing resonances below 4 kHz, but at higher repetition rates, the reflective surfaces that most significantly affect performance are located closer to, above, and below the discharge region, rather than at a distance further away from the discharge region and displaced laterally.

[0057]

[0075] Therefore, the potential for distortion is greatest when the sound wave returns at a time coinciding with the start of a new discharge. Thus, the amount of distortion generally depends on the relationship between the pulse repetition rate and the round-trip time-of-flight distance of the sound wave traveling at the speed of sound from the discharge region to the reflective surface and back within the laser discharge chamber. At higher repetition rates, e.g., in the range of 5.8 kHz to 6 kHz, reflective surfaces closer to the discharge region 340 dominate the resonant acoustic distortion effect. These include surfaces above and below the discharge region, such as the surface of the pre-onizer, main insulator, and anode support bar facing the discharge region.

[0058]

[0076] As described above, a pre-onizer is characterized by its configuration as electrodes placed inside a cylindrical tube made of a dielectric material such as ceramic. The pre-onizer tube typically has a smooth outer surface, which produces a type of coherent acoustic reflection that can result in resonance in the laser performance characteristics (e.g., bandwidth) at higher repetition rates, such as close to or exceeding 6 kHz.

[0059]

[0077] According to one aspect of one embodiment, at least a portion of the surface of a pre-onizer tube is engineered to have an acoustic scattering feature that functions as an acoustic baffle, which interacts with sound waves impacting the surface by scattering those sound waves, essentially randomizing the reflected waves so that they do not coherently return to the discharge region. The acoustic scattering feature is provided where at least a portion of the outer surface of the pre-onizer tube is positioned to face the discharge region, but it will be understood that the acoustic scattering feature may also be provided on other portions, including the entire outer surface of the tube. In this specification, including the claims, a surface on which an acoustic scattering feature is provided is referred to as an acoustic scattering surface. Here, “provided” is intended to mean processes such as molding that create the acoustic scattering feature during the manufacture of the pre-onizer tube, as well as processes that add the acoustic scattering feature to the wall / outer surface of the pre-onizer tube after the manufacture of the pre-onizer tube.

[0060]

[0078] The acoustic scattering feature can be created by any one of several possible methods. For example, the acoustic scattering feature may be realized by shaping the material constituting the pre-ionizer tube so that the surface of the pre-ionizer tube includes the acoustic scattering feature. As another example, the acoustic scattering feature may be machined from the outside of the wall of the pre-ionizer tube using a cutting tool. Other methods may be used, including installing a material layer with the acoustic scattering feature on the outer wall of the pre-ionizer tube.

[0061]

[0079] Those skilled in the art will understand that various parameters related to acoustic scattering features, such as their shape, depth, area, distribution (including spacing), surface coverage, and density (number of features per unit area), are modified according to specific application considerations. For example, with respect to depth, the range of acoustic wavelengths in question can be assumed to be defined by the physical size (width and height) of the laser discharge cross-section. It can be assumed that the influence from sound waves with wavelengths much smaller than the discharge cross-section is zero on average. It can also be assumed that sound waves with wavelengths much larger than the discharge cross-section create a pressure gradient that is insufficient to significantly adversely affect laser performance.

[0062]

[0080] Figure 6A is a non-scale cross-sectional view of a portion of the length of the pre-onizer tube wall 368 and electrode 367 relative to the discharge region 340. Figure 6B is an end view of the pre-onizer tube wall 368 and electrode 367 in Figure 6A. A typical discharge in the discharge region 340 of an ArF excimer laser may have a cross-section with a height (dimension H in Figure 6B) of approximately 2 mm (0.079'') and a width (dimension W in Figure 6B) of 14 mm (0.551''). Applying the acoustic quarter wavelength rule, the acoustic scattering feature should be the same size as at least one-quarter of the acoustic wavelengths in this range, and therefore, the exemplary range of depth for the acoustic scattering feature is approximately 0.02 inches to approximately 0.14 inches.

[0063]

[0081] Figure 7 is a cross-sectional view of a portion of the length of a pleyonizer tube wall 368 equipped with an acoustic scattering feature 500. As shown in Figure 7 and Figure 6B, the pleyonizer tube wall 368 may have a nominal thickness in the range of, for example, about 0.150 inches to 0.3 inches. In this specification, nominal thickness refers to the thickness of the area not having an acoustic scattering feature. This is shown as dimension T in Figures 6B and 7. In a given application, it may be required that the pleyonizer tube wall thickness be at least 0.125 inches in all places. For example, for a pleyonizer tube wall with a nominal thickness T of 0.190 inches, the maximum depth of the acoustic scattering feature 500 (the range F that penetrates below the outer surface 369 of the pleyonizer tube wall 368) may be 0.065 inches or less, given that a minimum thickness M of 0.125 inches should be preserved. This depth is more than sufficient to accommodate an effective acoustic scattering feature based on the design considerations described above. In some embodiments, the acoustic scattering feature portion has a penetration depth into the plyonizer tube wall 368 that is greater than half the nominal thickness of the plyonizer tube wall 368.

[0064]

[0082] Note that the cross-section of the example acoustic scattering feature section 500 shown in Figure 7 is semicircular, and the acoustic scattering feature section 500 itself is realized as a hemispherical depression or cavity on the surface of the pre-onizer tube that penetrates the wall of the pre-onizer tube. It will be understood that other shapes may be used, as will be explained in more detail below.

[0065]

[0083] Figure 8 is a projection of a portion of the outer surface 369 of the pre-ionizer tube wall 368, which is provided with an acoustic scattering feature section 500 to create an acoustic scattering surface 510. Generally, the acoustic scattering surface 510 is provided at least in the portion of the outer surface 369 that faces the discharge region 340 (Figure 5), and therefore receives and reflects sound waves from the discharge in the discharge region 340. In some cases, it may be desirable to provide the acoustic scattering feature section 500 over the entire outer surface 369, based on considerations such as ease of manufacture, installation, and maintenance.

[0066]

[0084] In the embodiment illustrated in Figure 8, the acoustic scattering features 500 are arranged in a periodic array, with the edge spacing between the nearest neighbors of the acoustic scattering features 500 denoted as S, and the size of each acoustic scattering feature 500 denoted as D. Generally, it is desirable to keep S small, as a larger S results in a larger amount of flat surface available for reflecting sound waves. In some embodiments, S is preferably in the range of 0.1 inches to 0.5 inches. The range of dimension D generally coincides with the range defined above as relating to acoustic reflection. Therefore, in some embodiments, D is preferably in the range of 0.1 inches to 0.3 inches. In some embodiments, S and D are selected to cover a proportion of the acoustic scattering surface 510 in the range of 10 percent to 100 percent. In some embodiments, the acoustic scattering features may have a density ranging from 3 acoustic scattering features per square inch to 100 acoustic scattering features per square inch.

[0067]

[0085] In the embodiment shown in Figure 8, the acoustic scattering feature portion 500 is again shown as a hemispherical depression or cavity. It will be understood that other shapes may be used. Also, in the embodiment shown in Figure 8, all of the acoustic scattering feature portions 500 are the same size and shape. Those skilled in the art will understand that the acoustic scattering feature portions 500 may be of different sizes and shapes.

[0068]

[0086] In the embodiment of Figure 8, the acoustic scattering feature portions 500 are arranged in a regular array. Alternatively, the acoustic scattering feature portions 500 may be randomly positioned in an irregular or non-periodic array, as shown in Figure 9. In the embodiment of Figure 9, the acoustic scattering feature portions 500 are again shown as hemispherical depressions or cavities. It will be understood that other shapes may be used. Also, in the embodiment of Figure 9, all of the acoustic scattering feature portions 500 are again all the same size and shape. Those skilled in the art will understand that at least some of the acoustic scattering feature portions 500 may differ in size and shape from the others.

[0069]

[0087] Those skilled in the art will understand that, insofar as the acoustic scattering features serve the purpose of redirecting sound waves in directions other than coherently returning them toward the subregion of the discharge from which the sound waves originated, acoustic scattering features can be created or arranged on the pleyonizer tube in arrangements other than those described herein. For example, the acoustic scattering features may be arranged as a series of linear baffles along the longitudinal axis of the pleyonizer tube. For example, Figure 10 is a side view of a pleyonizer 365 having acoustic scattering features 500 configured such that a portion of the axially extending surface has a series of triangular features, with one side of the triangle extending radially relative to the pleyonizer 365. Figure 11 is a perspective view of the pleyonizer tube 366 of Figure 10.

[0070]

[0088] The shape of the acoustic scattering feature section 500 can also vary. Figure 12A is a magnified view of the portion of the pre-ionizer tube 366 within the dotted box A in Figure 11. As described above, the acoustic scattering feature section 500 is realized as a single triangular feature section, with one side of the triangle aligned parallel to the radius of the pre-ionizer tube 366 of the pre-ionizer. Figure 12B shows another configuration of the acoustic scattering feature section 500, in which each of the triangles has an outwardly pointed vertex at an angle of less than 45 degrees, and both sides of the triangles are oriented at an angle to the radial direction of the pre-ionizer tube. Figure 12C illustrates one embodiment in which the acoustic scattering feature section 500 has a rounded shape that protrudes from the surface of the pre-ionizer tube. Figure 12D illustrates one embodiment in which each of the acoustic scattering feature sections has a substantially semicircular projection. Those skilled in the art will readily understand that other shapes may be used. Furthermore, in the embodiments described above, all acoustic scattering feature portions 500 have the same general shape and dimensions. Those skilled in the art will readily understand that some of the acoustic scattering feature portions 500 may have different shapes and dimensions from those of the other acoustic scattering feature portions 500.

[0071]

[0089] It will be understood that the acoustic scattering features on the surface of the plyonizer tube wall have an engineered surface with local deviations from two-dimensional planarity, and as a result, the acoustic scattering features can be considered equivalent to having height and / or depth and extending into and out of the plyonizer tube wall, or into and out of the plyonizer tube wall surface.

[0072]

[0090] In addition to or instead of the mitigation measures described above, according to another aspect of one embodiment, at least a portion of the pre-onizer tube is configured to exhibit a surface that is angled to the discharge region, for example, by having a taper instead of a cylindrical cross-section. Thus, when the pre-onizer tube is installed in the chamber, at least some surfaces of the pre-onizer do not reflect sound waves from the discharge region back coherently to the source of those sound waves. The pre-onizer tube may have any shape that achieves this purpose, including a frustoconical (truncated cone) shape, two truncated cones (complex quadrilateral (bow tie) shape) with large and large diameters or small and small diameters combined, or a surface of revolution such as a hyperboloid.

[0073]

[0091] Figures 13A and 13B show a pre-onizer tube 600 according to one embodiment. The pre-onizer tube 600 contains an electrode 610. However, the pre-onizer tube 600 is not configured as a cylinder. Instead, the pre-onizer tube 600 is tapered from one end 615 to the other end 625. The pre-onizer tube 600 has a circular cross-section with an axis of symmetry 627, as shown in Figure 13B. The axis of symmetry 627 of the pre-onizer tube 600 is approximately parallel to the optical axis 342 of the discharge region 340, but the pre-onizer tube wall 620 is positioned at a non-zero angle with respect to the optical axis 342 of the discharge region 340.

[0074]

[0092] End 615 has an outer diameter A, and end 625 has an outer diameter B, where B is smaller than A. Therefore, the outer diameter of the plyonizer tube 600 decreases linearly from A to B over its length L, forming a truncated cone shape, i.e., a frustoconical plyonizer tube. As a result of this taper, the surface of the plyonizer tube wall 620 forms an angle θ with the discharge region 340. The magnitude of the angle θ depends on the size of the outer diameter A, the size of the outer diameter B, and the length L of the plyonizer tube 600. Generally,

[0075]

number

[0076] This is the result.

[0077]

[0093] The magnitude of the angle θ can be, for example, in the range of approximately 0.2° to 2°. Smaller angles θ do not adequately redirect sound waves from the discharge region. Larger angles θ begin to have detrimental effects on the function of the pleionize tube and may require rearranging of components within the chamber, but do not significantly contribute additionally to the reduction of resonance.

[0078]

[0094] The dimensions of the pre-ionizer tube 600 will generally be determined by the requirements of the specific application. In some embodiments, it may be beneficial to make the outer diameter of one of the ends 615, 625 of the pre-ionizer 600 the same as the outer diameter of a conventional cylindrical pre-ionizer tube. This will be helpful for the installation of the pre-ionizer tube 600 and for modifying chambers that are already deployed in the field. In some embodiments, it may be advantageous to maintain the outer diameter of the pre-ionizer tube 600 so that it remains shielded from the gas flow by the surrounding structure, such as the main insulator 360 (Figure 4). However, it should be noted that in this context, the main insulator may be redesigned to accommodate pre-ionizer tubes with larger diameters. Generally, the outer diameter A may range from about 0.25 inches to about 1 inch. A smaller outer diameter B may also have a diameter in the range of about 0.25 inches to about 0.95 inches, but B is kept smaller than A.

[0079]

[0095] According to another aspect of one embodiment, as shown in Figures 13A and 13B, the inner diameter A' of the pre-ionizer tube 600 at end 615 may be larger than the inner diameter B' of the pre-ionizer tube 600 at end 625, so as to maintain a more uniform thickness T of the wall 620 of the pre-ionizer tube 600.

[0080]

[0096] Accordingly, the pre-ionizer tube 600 is configured as an elongated hollow tube having a first end 615, a second end 625, and a circularly symmetric axis 627 extending along the length of the pre-ionizer tube 600 from the center of the first end 615 to the center of the second end 625, wherein the outer diameter of at least one longitudinal section of the elongated hollow tube changes linearly (e.g., increases or decreases) as a function of the longitudinal distance (measured along the length L) from the first end 615. The longitudinal section may extend along the entire length L of the pre-ionizer tube 600, as shown in the figure, or it may extend only to a portion of the length L of the pre-ionizer tube 600.

[0081]

[0097] According to another aspect of one embodiment, the pre-ionizer tube 600 as shown in Figures 13A and 13B may be manufactured using a two-part electrode comprising two parts having different diameters to fit into respective pre-ionizer tube sockets of different diameters at each end. The pre-ionizer tube 600 may also be manufactured, depending on the specific application, by machining a ceramic material or by molding and then curing a ceramic material.

[0082]

[0098] The pre-onizer tube may have a shape other than a frustoconical shape, as long as the objective of having a surface that is not parallel to the vertical optical axis of the discharge region is satisfied. Figure 14A shows the configuration of a pre-onizer tube 630 having a roughly bow-tie configuration, with its two ends 632 and 634 having the same outer diameter, and the intermediate portion 636 being narrowed to have a smaller outer diameter.

[0083]

[0099] Figure 14B shows a plyonizer tube 640 in the form of two truncated cones joined by a large diameter end, where the two small ends 642 and 644 have the same outer diameter, but the intermediate portion 646 has an enlarged outer diameter, causing the plyonizer tube 640 to exhibit a surface at an angle to the discharge region. Figure 14C shows a plyonizer tube 650 formed by a hyperbola forming a surface of rotation, such as a hyperbolic surface, which forms a surface not parallel to the discharge region. It will be obvious to those skilled in the art that in any of these embodiments, the two ends do not necessarily have to have the same outer diameter. It will also be obvious to those skilled in the art that other configurations with uneven surfaces are possible.

[0084]

[0100] In the embodiments described above, the pleyonizer tube may have a conventional unstructured surface. However, as stated above, the pleyonizer tube may have both a structured or engineered (e.g., acoustically baffled) surface and a tapered cross-section. Figure 15 shows an example of such a tapered and baffled pleyonizer tube 660 provided with a structured surface 670. The structured surface 670 may be any of the types described above. The pleyonizer tube 660 in the configuration of Figure 15 thus employs several measures to redirect the acoustic energy so that it does not simply reflect back to the part of the discharge region that generated the acoustic energy.

[0085]

[0101] Part of the above explanation relates to functional block diagrams, where some functions are assigned to some blocks and other functions to other blocks. It should be understood that the division and assignment between blocks are arbitrary, and that different divisions and assignments are possible as long as the overall function is performed as described above.

[0086]

[0102] The above description includes examples of several embodiments. While it is certainly not possible to describe all possible combinations of each component or methodology of these embodiments, those skilled in the art will recognize that many further combinations and permutations of elements of various embodiments are possible based on this disclosure. Therefore, the embodiments described are intended to represent and cover all such changes, modifications, and variations that fall within the spirit and scope of the appended claims.

[0087]

[0103] Furthermore, since the term “comprising” is interpreted as a transitional term when used in a claim, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be as comprehensive as “comprising.” Also, while multiple elements of a described aspect and / or embodiment may be described or claimed as singular, they are considered plural unless otherwise specified. In addition, any aspect and / or embodiment in whole or in part may be used in conjunction with any other aspect and / or embodiment in whole or in part, unless otherwise specified.

[0088]

[0104] The aspects and examples of this disclosure may be further described using the following clauses. 1. A play-onizer for laser systems, A tube having an outer surface and a tube wall, configured as a substantially cylindrical hollow tube extending axially in a first direction, wherein at least a portion of the outer surface is provided with a plurality of acoustic scattering feature portions, An electrode positioned at least partially inside the tube, A playonizer equipped with this feature. 2. A pre-ionizer as described in Clause 1, comprising a tube made of dielectric material. 3. The plyonizer according to Clause 1, wherein the acoustic scattering feature portion has a penetration depth into the tube wall greater than half the nominal thickness of the tube wall. 4. The laser system operates at 6 kHz, and the acoustic scattering feature section has a penetration depth of at least 0.063 inches into the tube wall, as described in Clause 1 of the playonizer. 5. The laser system is configured to generate a discharge in a discharge region having a height H and a width W, and the penetration depth of the acoustic scattering feature into the tube wall is in the range of 1 / 4H to 1 / 4W, including the values ​​at both ends, as described in Clause 1, for the playonizer. 6. The playonizer according to Clause 1, wherein the laser system is configured to generate a discharge in the discharge region, and the acoustic scattering feature is provided on at least a portion of the outer surface facing the discharge area. 7. The playonizer described in Clause 1, wherein the acoustic scattering feature is provided on substantially the entire outer surface. 8. The plyonizer according to Clause 1, wherein the acoustic scattering feature portion is manufactured by forming the acoustic scattering feature portion on at least a portion of the outer surface. 9. The playonizer according to Clause 1, wherein the plurality of acoustic scattering feature units are arranged in an array provided on at least a portion of the outer surface. 10. The array is nonperiodic, as described in Clause 9 of the playonizer. 11. The playonizer described in Clause 1, wherein the nearest of the multiple acoustic scattering feature areas is separated by a distance between its edges ranging from 0.01 inches to 0.5 inches. 12. The playonizer according to Clause 1, wherein the acoustic scattering features are arranged to have a density ranging from 3 acoustic scattering features per square inch to 100 acoustic scattering features per square inch. 13. The playonizer according to Clause 1, wherein the plurality of acoustic scattering feature portions each have an area ranging from 0.1 square inch to 0.5 square inch. 14. The playonizer according to Clause 1, wherein the multiple acoustic scattering feature portions have a total outer surface coverage ranging from 10 percent to 100 percent. 15. A playonizer for excimer lasers, A pipe body having a pipe wall, the pipe wall having an external surface, A plurality of baffles provided on an acoustic scattering surface on the outer surface, wherein the acoustic scattering surface extends longitudinally along the length of the tube body, and each baffle is positioned and sized to scatter acoustic reflections from the acoustic scattering surface, An electrode positioned at least partially within the tube body, A playonizer equipped with this feature. 16. A pre-ionizer according to Clause 15, wherein the tube wall comprises a dielectric material. 17. A preionizer as described in Clause 15, wherein the baffle has a depth of penetration into the tube wall greater than half the thickness of the tube wall. 18. The excimer laser operates at 6 kHz, and the baffle has a penetration depth of at least 0.063 inches into the tube wall, as described in Clause 15. 19. The playonizer according to Clause 15, wherein the excimer laser is configured to generate a discharge in a discharge region having a height H and a width W, and the depth of the baffle's penetration into the tube wall is in the range of 1 / 4H to 1 / 4L, including the values ​​at both ends. 20. The playonizer according to Clause 15, wherein the excimer laser is configured to generate a discharge in the discharge region, and the acoustic scattering surface comprises a portion of the external surface facing the discharge area. 21. The acoustic scattering surface comprises substantially the entire external surface of the playonizer as described in Clause 15. 22. The sound scattering surface is created by forming a baffle into the tube wall, as described in Clause 15 of the plyonizer. 23. The plionizer according to Clause 15, wherein the acoustic scattering surface comprises an array of baffles provided on the external surface. 24. The array is nonperiodic, as described in Clause 23. 25. The playonizer as described in Clause 15, wherein the baffles are arranged to have a density ranging from 3 baffles per square inch to 100 baffles per square inch. 26. A playonizer as described in Clause 15, comprising multiple baffles, each having an area ranging from 0.1 square inch to 0.5 square inch. 27. The baffle has an edge spacing between the nearest adjacent baffles in the range of 0.01 inches to 0.5 inches, as described in Clause 15. 28. A pre-ionizer as described in Clause 15, with multiple baffles covering 10 to 100 percent of the external surface. 29. A discharge chamber for a laser system, A first electrode having a first electrode discharge surface, A second electrode having a second electrode discharge surface, wherein the first electrode discharge surface is positioned facing the second electrode discharge surface and spaced apart from the second electrode discharge surface so as to define a discharge gap, A playonizer including a playonizer tube extending laterally adjacent to a first electrode, wherein the surface of the playonizer tube facing the discharge gap is provided with a plurality of acoustic scattering feature portions sized and arranged to scatter sound waves from the discharge gap, A discharge chamber equipped with a discharge chamber. 30. The discharge chamber according to Clause 29, wherein the pre-ionizer tube comprises a dielectric material. 31. The discharge chamber according to Clause 29, wherein the acoustic scattering feature section has a penetration depth into the pre-onizer tube facing the discharge gap, and the penetration depth is greater than half the nominal thickness of the wall of the pre-onizer tube. 32. The discharge chamber according to Clause 29, wherein the discharge chamber operates at 6 kHz and the acoustic scattering feature section has an intrusion depth of at least 0.063 inches into the pre-onizer tube. 33. The discharge chamber according to Clause 29, configured to generate a discharge in a discharge region having a height H and a width W, wherein the depth of entry of the acoustic scattering feature portion into the pre-onizer tube is in the range of 1 / 4H to 1 / 4W, including the values ​​at both ends. 34. The discharge chamber according to Clause 29, wherein the acoustic scattering surface is produced by forming an acoustic scattering feature portion on the wall of the pre-onizer tube. 35. The discharge chamber according to Clause 29, wherein the acoustic scattering surface comprises an array of acoustic scattering features provided on the surface of a pre-onizer tube facing the discharge gap. 36. The array is aperiodic, as described in Clause 35. 37. The discharge chamber according to Clause 29, wherein each acoustic scattering feature is spaced at an interval of 0.01 inches to 0.5 inches from the nearest acoustic scattering structure. 38. The discharge chamber according to Clause 29, wherein the acoustic scattering features are arranged on the surface of the pre-onizer tube facing the discharge gap, having a density ranging from 3 acoustic scattering features per square inch to 100 acoustic scattering features per square inch. 39. The discharge chamber according to Clause 29, wherein the plurality of acoustic scattering feature areas each have an area ranging from 0.1 square inch to 0.5 square inch. 40. The discharge chamber as described in Clause 29, wherein the acoustic scattering feature area covers approximately 10 to 100 percent of the surface of the pre-onizer tube facing the discharge gap.

[0089]

[0105] The embodiments and examples described above, as well as other embodiments, are within the scope of the following claims.

Claims

1. A play-onizer for laser systems, A tube having an outer surface and a tube wall, configured as a substantially cylindrical hollow tube extending axially in a first direction, wherein at least a portion of the outer surface is provided with a plurality of acoustic scattering feature portions, An electrode positioned at least partially within the tube, A playonizer equipped with this feature.

2. The playonizer according to claim 1, wherein the tube comprises a dielectric material.

3. The playonizer according to claim 1, wherein the acoustic scattering feature portion has a penetration depth into the tube wall that is greater than half the nominal thickness of the tube wall.

4. The playonizer according to claim 1, wherein the laser system operates at 6 kHz, and the acoustic scattering feature portion has a penetration depth of at least 0.063 inches into the tube wall.

5. The playonizer according to claim 1, wherein the laser system is configured to generate a discharge in a discharge region having a height H and a width W, and the penetration depth of the acoustic scattering feature portion into the tube wall is in the range of 1 / 4H to 1 / 4W, including both end values.

6. The playonizer according to claim 1, wherein the laser system is configured to generate a discharge in the discharge region, and the acoustic scattering feature portion is provided on at least a portion of the outer surface that is arranged to face the discharge area.

7. The playonizer according to claim 1, wherein the acoustic scattering feature portion is provided on substantially the entire outer surface.

8. The playonizer according to claim 1, wherein the acoustic scattering feature portion is produced by molding the acoustic scattering feature portion onto at least a part of the outer surface.

9. The playonizer according to claim 1, wherein the plurality of acoustic scattering feature portions are arranged in an array provided on at least a portion of the outer surface.

10. The playonizer according to claim 9, wherein the array is aperiodic.

11. The playonizer according to claim 1, wherein the closest of the plurality of acoustic scattering feature portions is spaced apart by a distance of 0.01 inches to 0.5 inches between their edges.

12. The playonizer according to claim 1, wherein the acoustic scattering feature portions are arranged to have a density ranging from 3 acoustic scattering feature portions per square inch to 100 acoustic scattering feature portions per square inch.

13. The playonizer according to claim 1, wherein the plurality of acoustic scattering feature portions each have an area in the range of 0.1 square inches to 0.5 square inches.

14. The playonizer according to claim 1, wherein the plurality of acoustic scattering feature portions have a total coverage of the outer surface in the range of 10 percent to 100 percent.

15. A playonizer for excimer lasers, A pipe body having a pipe wall, the pipe wall having an external surface, A plurality of baffles provided on the acoustic scattering surface of the outer surface, wherein the acoustic scattering surface extends in the longitudinal direction along the length of the pipe body, and each of the baffles is arranged and sized to scatter acoustic reflections from the acoustic scattering surface, An electrode positioned at least partially within the tube body, A playonizer equipped with this feature.

16. The playonizer according to claim 15, wherein the tube wall comprises a dielectric material.

17. The playonizer according to claim 15, wherein the baffle has a depth of penetration into the tube wall that is greater than half the thickness of the tube wall.

18. The playonizer according to claim 15, wherein the excimer laser operates at 6 kHz and the baffle has a penetration depth of at least 0.063 inches into the tube wall.

19. The playonizer according to claim 15, wherein the excimer laser is configured to generate a discharge in a discharge region having a height H and a width W, and the depth of the baffle's penetration into the tube wall is in the range of 1 / 4H to 1 / 4L, including the values ​​at both ends.

20. The playonizer according to claim 15, wherein the excimer laser is configured to generate a discharge in the discharge region, and the acoustic scattering surface comprises a portion of the external surface facing the discharge area.

21. The playonizer according to claim 15, wherein the acoustic scattering surface comprises substantially the entirety of the external surface.

22. The pre-ionizer according to claim 15, wherein the acoustic scattering surface is produced by forming the baffle into the wall of the tube.

23. The playonizer according to claim 15, wherein the acoustic scattering surface comprises an array of baffles provided on the outer surface.

24. The playonizer according to claim 23, wherein the array is aperiodic.

25. The playonizer according to claim 15, wherein the plurality of baffles are arranged to have a density ranging from three baffles per square inch to 100 baffles per square inch.

26. The playonizer according to claim 15, wherein the plurality of baffles each have an area ranging from 0.1 square inches to 0.5 square inches.

27. The playonizer according to claim 15, wherein the baffle has an edge spacing between the nearest adjacent baffles in the range of 0.01 inches to 0.5 inches.

28. The playonizer according to claim 15, wherein the plurality of baffles cover 10 percent to 100 percent of the outer surface.

29. A discharge chamber for a laser system, A first electrode having a first electrode discharge surface, A second electrode having a second electrode discharge surface, wherein the first electrode discharge surface is positioned facing the second electrode discharge surface and spaced apart from the second electrode discharge surface so as to define a discharge gap, A playonizer including a playonizer tube extending laterally adjacent to the first electrode, wherein the surface of the playonizer tube facing the discharge gap is provided with a plurality of acoustic scattering feature portions sized and arranged to scatter sound waves from the discharge gap, A discharge chamber equipped with a discharge chamber.

30. The discharge chamber according to claim 29, wherein the pre-ionizer tube comprises a dielectric material.

31. The discharge chamber according to claim 29, wherein the acoustic scattering feature portion has a depth of penetration into the pre-onizer tube facing the discharge gap, and the penetration depth is greater than half the nominal thickness of the wall of the pre-onizer tube.

32. The discharge chamber according to claim 29, wherein the discharge chamber operates at 6 kHz, and the acoustic scattering feature portion has a penetration depth of at least 0.063 inches into the pre-onizer tube.

33. The discharge chamber according to claim 29, wherein the discharge chamber is configured to generate a discharge in a discharge region having a height H and a width W, and the depth of the acoustic scattering feature portion entering the pre-onizer tube is in the range of 1 / 4H to 1 / 4W, including both ends.

34. The discharge chamber according to claim 29, wherein the acoustic scattering surface is produced by forming the acoustic scattering feature portion on the wall of the pre-ionizer tube.

35. The discharge chamber according to claim 29, wherein the acoustic scattering surface comprises an array of acoustic scattering feature portions provided on the surface of the pre-ionizer tube facing the discharge gap.

36. The discharge chamber according to claim 35, wherein the array is nonperiodic.

37. The discharge chamber according to claim 29, wherein the edges of each of the aforementioned acoustic scattering feature portions are spaced apart by a distance of 0.01 inches to 0.5 inches from the nearest acoustic scattering structure.

38. The discharge chamber according to claim 29, wherein the acoustic scattering feature portions are arranged on the surface of the preionizer tube facing the discharge gap, with a density ranging from 3 acoustic scattering feature portions per square inch to 100 acoustic scattering feature portions per square inch.

39. The discharge chamber according to claim 29, wherein the plurality of acoustic scattering feature portions each have an area in the range of 0.1 square inches to 0.5 square inches.

40. The discharge chamber according to claim 29, wherein the acoustic scattering feature portion covers about 10 percent to 100 percent of the surface of the pre-onizer tube facing the discharge gap.

41. A play-onizer for laser systems, An elongated hollow tube having a first end, a second end, and a circularly symmetric axis extending along the length of the tube from the center of the first end to the center of the second end, wherein the outer diameter of at least one section in the longitudinal direction of the elongated hollow tube changes from the first end, An electrode positioned at least partially within the elongated hollow tube, A playonizer equipped with this feature.

42. The pre-ionizer according to claim 41, wherein the longitudinal section comprises the entire length of the elongated hollow tube.

43. The playonizer according to claim 41, wherein the outer diameter of one section in the longitudinal direction increases linearly as a function of the longitudinal distance from the first end.

44. The playonizer according to claim 41, wherein the outer diameter of one section in the longitudinal direction decreases linearly as a function of the longitudinal distance from the first end.

45. The playonizer according to claim 41, wherein at least a portion of the outer surface of the elongated hollow tube has a plurality of acoustic scattering feature portions.

46. A discharge chamber for a laser system, A first electrode having a first electrode discharge surface, A second electrode having a second electrode discharge surface, wherein the first electrode discharge surface is positioned facing the second electrode discharge surface and spaced apart from the second electrode discharge surface so as to define a discharge region, A playonizer including a substantially frustoconical playonizer tube extending laterally adjacent to the first electrode, wherein the playonizer is oriented such that the surface of the playonizer tube forms an angle with respect to the discharge region, A discharge chamber equipped with a discharge chamber.

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