Discharge chamber gas replenishment system

Abstract

A lasing gas replenishment system for a discharge chamber in a deep ultraviolet radiation source in which an axial flow turbine is used to refresh lasing gas in the discharge chamber with a higher clearing ratio so that lasing gas in the discharge region may be replenished rapidly enough to support higher pulse repetition rates.

Description

DISCHARGE CHAMBER GAS REPLENISHMENT SYSTEMCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of US application 63 / 614,747 which was filed on 26 December 2023 and which is incorporated herein in its entirety by reference.FIELD

[0002] The disclosed subject matter relates to systems for recirculating lasing gas in a laser discharge chamber such as in a deep ultraviolet (DUV) radiation laser radiation source.BACKGROUND

[0003] Photolithography is a process by which semiconductor circuitry is patterned on a substrate such as a silicon wafer. A photolithography radiation source provides DUV radiation (radiation having wavelengths in a range of about 100 nanometers (nm) to about 400 nm) used to expose a photoresist on the wafer. Often, the radiation source is a laser source and the radiation is a pulsed laser beam. The radiation beam is passed through a beam delivery unit, then through or reflected by a reticle or a mask, and then projected onto a silicon wafer coated with photoresist. In this way, a chip design is patterned onto a photoresist that is then etched and cleaned.

[0004] Many systems that produce a beam of DUV laser radiation do so by creating discharges produced in a discharge region between electrodes in a discharge chamber. More precisely, the DUV discharge chamber has a pair of electrodes (a pair being comprised of one anode and one cathode) arranged to generate plasma discharges from a lasing gas (generally a gas mixture) when a high voltage is applied across the electrodes. The discharge is pulsed at a repetition rate of, for example, 6 kHz (6000 times per second), and thus produces a train or burst of DUV radiation emission pulses.

[0005] During a discharge the lasing gas in the discharge region between the electrodes becomes depleted of one or more components. Thus the DUV discharge chamber typically includes at least one cross flow blower to establish a flow of gas through the discharge region. The gas flow replaces the depleted gas in the discharge region with fresh gas from elsewhere in the discharge chamber in preparation for the next discharge event.

[0006] Cross flow blowers are inefficient and the motor for the cross flow blower can consume a substantial amount of energy while driving a flow of gas in the discharge chamber. The amount of energy can constitute a non-negligible fraction of the total energy used by the overall DUV laser system in discharge production. In addition, demands for increased production will necessitate the use of increased pulse repetition rates. This will reduce the time between pulses, and so the time permitted to clear the spent gas from the discharge region between pulses. Thus the clearance speed will need to be increased. This would cause a cross flow blower to consume even more power.

[0007] It would be advantageous to improve the process of replenishing gas in the discharge region of a DUV laser source without unduly increasing energy consumption. It is in this context that the need for the subject matter of the present disclosure arises.SUMMARY

[0008] This summary is provided as a prelude to the full description below to introduce the presently disclosed subject matter. It is not intended to be a comprehensive overview of all contemplated embodiments nor to distinguish as key or critical any elements of any embodiments.

[0009] According to an aspect of an embodiment there is disclosed a gas replenishment system for a discharge chamber for a deep ultraviolet laser, the gas replenishment system comprising a discharge chamber enclosure, a gas conduit having a first port arranged to introduce gas into the discharge chamber enclosure and a second port arranged to exhaust gas from the discharge chamber enclosure, and an axial flow turbine positioned in the gas conduit, the axial flow turbine having an axial shaft and a plurality of blades attached radially to the axial shaft with the axial shaft being arranged to be parallel to a flow of gas through the axial flow turbine.

[0010] The gas replenishment system may further comprise a motor coupled to the axial shaft. The gas replenishment system may further comprise a magnetic coupler arranged to magnetically couple rotational force from the motor to the axial shaft. The gas replenishment system may further comprise a second motor coupled to the axial shaft. The gas replenishment system may further comprise a second magnetic coupler arranged to magnetically couple rotational force from the second motor to the axial shaft.

[0011] The motor may be positioned outside of the gas conduit and the discharge chamber enclosure.

[0012] The gas replenishment system may further comprise at least one heat exchanger arranged to extract heat from the gas in the gas conduit. The gas replenishment system may further comprise a heat exchanger positioned in the gas conduit between the axial flow turbine and the first port. The gas replenishment system may further comprise a flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port. The gas replenishment system may further comprise a combined heat exchanger and flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.

[0013] According to another aspect of an embodiment there is disclosed a gas replenishment system for a discharge chamber for a deep ultraviolet laser, the gas replenishment system comprising a gas conduit having a first port adapted to be connected to the discharge chamber to introduce gas into the discharge chamber and a second port adapted to be connected to the discharge chamber to exhaust gas from the discharge chamber, and an axial flow turbine positioned in the gas conduit, the axial flow turbine having an axial shaft and a plurality of blades attached radially to the axial shaft with the axial shaft being arranged to be parallel to a flow of gas through the axial flow turbine.

[0014] The gas replenishment system may further comprise a motor coupled to the axial shaft. The motor may be positioned outside of the gas conduit.

[0015] The gas replenishment system may further comprise a magnetic coupler arranged to magnetically couple rotational force from the motor to the shaft. The gas replenishment system may further comprise a heat exchanger positioned in the gas conduit between the axial flow turbine and the first port. The gas replenishment system may further comprise a flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port. The gas replenishment system may further comprise a combined heat exchanger and flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.

[0016] According to another aspect of an embodiment there is disclosed a gas replenishment system for a discharge chamber for a deep ultraviolet laser, the gas replenishment system comprising a gas conduit having a first port adapted to be connected to the discharge chamber to introduce gas into the discharge chamber and a second port adapted to be connected to the discharge chamber to exhaust gas from the discharge chamber to circulate the gas through the discharge chamber, the gas conduit establishing a gas return path that does not pass through the discharge chamber, and an axial flow turbine positioned in the gas conduit, the axial flow turbine having an axial shaft and an impeller comprising a plurality of blades attached radially to the axial shaft to have an axis of rotation coinciding with the axial shaft with the axis of rotation being arranged to be parallel to a flow of gas through the impeller, the axial flow turbine being arranged to accelerate the gas in an axial direction towards the first port.

[0017] The gas replenishment system may further comprise a motor coupled to the axial shaft. The gas replenishment system the motor may be positioned outside of the gas conduit. The gas replenishment system may further comprise a magnetic coupler arranged to magnetically couple rotational force from the motor to the shaft. The gas replenishment system may further comprise a heat exchanger positioned in the gas conduit between the axial flow turbine and the first port. The gas replenishment system may further comprise a flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port. The gas replenishment system may further comprise a combined heat exchanger and flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.

[0018] Further embodiments, features, and advantages of the subject matter of the present disclosure, as well as the structure and operation of the various embodiments, are described in detail below with reference to the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the presently disclosed subject matter and, together with the description, further serve to explain the principles of the presently disclosed subject matter and to enable a person skilled in the relevant art to make and use the presently disclosed subject matter. The drawings are not to scale unless otherwise indicated.

[0020] FIG. 1 is a functional block diagram, not to scale, of an overall broad conception of a photolithography system.

[0021] FIG. 2 is a functional block diagram, not to scale, of an overall broad conception of an illumination system such as might be used in the photolithography system of FIG. 1.

[0022] FIG. 3 is a cross-sectional diagram of a discharge chamber for a DUV radiation source.

[0023] FIG. 4 is a cross-sectional diagram of a discharge chamber for a DUV radiation source according to an aspect of an embodiment.

[0024] FIG. 5 is a perspective view of a discharge chamber for a DUV radiation source according to an aspect of an embodiment.

[0025] FIG. 6 is a partially cutaway perspective view of the discharge chamber of FIG. 5.

[0026] FIG. 7A is a cross section of a section of a conduit including a heat exchanger / flow homogenizer according to an aspect of an embodiment.

[0027] FIG. 7B is a cross section of a heat exchanger / flow homogenizer taken along line B-B of FIG. 7A.

[0028] It is noted that the scope of the presently disclosed subject matter is 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 based on the teachings presented herein.DETAILED DESCRIPTION

[0029] Various embodiments are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, specific details are set forth in order to promote a thorough understanding of one or more embodiments. It may be evident in some or all instances, however, that variations of any described embodiment can be implemented without departing from the teachings provided by this disclosure. In other instances, well-known structures and devices are shown in block diagram form in order to streamline description of one or more embodiments.

[0030] FIG. 1 shows a photolithography system 100 that includes an illumination system 105. As described more fully below, the illumination system 105 includes a radiation source that produces a pulsed radiation beam 110 and directs it to a photolithography exposure apparatus 115 such as a scanner that patterns microelectronic features on a wafer 120. The wafer 120 is placed on a wafer table 125 constructed to hold wafer 120 and connected to a positioner 130 configured to accurately position the wafer 120 for processing. The pulsed radiation beam 110 may have a wavelength in the DUV range.

[0031] The photolithography exposure apparatus 115 includes an optical arrangement 135 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 the pulsed radiation beam 110 or in a plane that is perpendicular to the optical axis. The objective arrangement includes a projection lens andenables an image transfer to occur from the mask to photoresist on the wafer 120. The illumination system 105 adjusts the range of angles for the pulsed radiation beam 110 impinging on the mask. The illumination system 105 also homogenizes (makes uniform) the intensity distribution of the pulsed radiation beam 110 across the mask.

[0032] The photolithography exposure apparatus 115 can include, among other features, a lithography controller 140 that controls how layers are printed on the wafer 120. The lithography controller 140 may include a memory that stores information such as process recipes that determine the parameters of the beam including a length of the exposure on the wafer 120 based on, for example, the mask used, as well as other factors that affect exposure. During lithography, a burst of pulses of the pulsed radiation beam 110 illuminates the same area of the wafer 120 to constitute an illumination dose.

[0033] The photolithography system 100 also preferably includes a control system 145. In general, the control system 145 includes one or more of digital electronic circuitry, computer hardware, firmware, and software. The control system 145 can be centralized or be partially or wholly distributed throughout the photolithography system 100 and may or may not be part of an overall control system for the photolithography system 100.

[0034] FIG. 2 shows a pulsed laser source that produces a pulsed laser beam as the radiation beam 110 as an example of an illumination system 105. FIG. 2 shows a two-chamber laser system as a nonlimiting 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. The gas discharge laser system may include, e.g., a solid state or gas discharge master oscillator (“MO”) seed laser system 200, an amplification stage, e.g., a power ring amplifier (“PRA”) stage 205, relay optics 210, and laser system output subsystem 215. The MO seed system 200 may include, e.g., an MO discharge chamber 220 which includes a pair of electrodes 222 and 224.

[0035] The MO seed laser system 200 may also include a master oscillator output coupler (“MO OC”) 230, which may comprise a partially reflective mirror, forming an MO discharge chamber 220 with an oscillator cavity, defined in part by a reflective grating (not shown) in a line narrowing module (“LNM”) 235, that oscillates to generate the seed laser output pulse. The MO seed laser system 200 may also include a line-center analysis module (“LAM”) 240. A 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, e.g., a multi prism beam expander (not shown) and an optical delay path (not shown).

[0036] The amplification stage 205 may include, e.g., a PRA discharge chamber 250, 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 255. The beam may be redirected back through the gain medium in the PRA discharge chamber 250 by a beam reverser (“BR”) 260. The PRA WEB 255 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. The PRA discharge chamber 250 may also include a pair of electrodes 252 and 254.

[0037] The laser output radiation beam of pulses from the PRA discharge chamber 250 then passes through the PRA WEB 255. A bandwidth analysis module (“BAM”) 265 is arranged to receive the output laser radiation beam of pulses from the PRA WEB 255 and divert a portion of the radiation beam for metrology purposes, e.g., to measure the output linewidth, bandwidth, and pulse energy. The remainder of the radiation beam then passes to an optical pulse stretcher (“OPuS”) 270 and an autoshutter, in this case a combined autoshutter metrology module (“CASMM”) 275, which may also be the location of a pulse energy meter. The OPuS 270 may accordingly be arranged to receive the laser beam from the BAM 265 and direct its output to the CASMM 275.

[0038] The PRA discharge chamber 250 and the MO discharge chamber 220 are configured as chambers in which electrical discharges between the electrodes cause lasing gas discharges in a lasing gas to create an inverted population of high energy molecules or excimers, including, e.g., ArF, KrF, F2, XeF, and / or XeCl, to produce relatively broad band radiation that may be line narrowed to a relatively very narrow bandwidth and center wavelength selected in the LNM 235.

[0039] FIG. 3 is a stylized cross-sectional diagram of a discharge chamber 300 using a cross flow blower. The laser discharge chamber 300 may serve, for example, as the PRA discharge chamber 250 or the MO discharge chamber 220. The discharge chamber 300 includes an upper electrode 310 acting as a cathode and a lower electrode 320 acting as an anode. The electrodes are generally elongated in a lengthwise direction orthogonal to the plane of the figure. Thus, if the figure is in the YZ plane as indicated then the electrodes extend in the + / - X direction. One or both of the lower electrode 320 and the upper electrode 310 may be entirely contained in the pressure envelope of discharge chamber 300 defined by the chamber wall 305 or one of the electrodes may not be so contained. Easing gas discharges occur in the gap between the two electrodes. Also shown in FIG. 3 are an upper insulator 315 and a lower insulator / anode support bar 325.

[0040] An applied voltage supply establishes a voltage gradient between upper electrode 310 and lower electrode 320. It will be understood that this is a relative rather than absolute polarity, that is, relative to the polarity of the lower electrode 320, which will generally be in electrical contact with the body 305 of the chamber 300 and so is held at a ground (0) potential. The upper electrode 310 is charged to a large (for example ~20 kV) negative voltage. This voltage gradient causes discharges in the lasing gas in a discharge region in the gap between the electrodes. As mentioned, in this arrangement the upper electrode in this example is a cathode and will be referred to as such herein. Similarly the lower electrode in this example is an anode and will be referred to as such herein. It will be understood that these respective roles may be switched.

[0041] As mentioned, during a discharge the gas in the discharge region between the cathode 310 and anode 320 becomes depleted of one or more components. It thus is necessary to replenish the gas between pulses by introducing fresh gas into the discharge region. This fresh gas is drawn from the gas circulating in the discharge chamber. Towards this end, the discharge chamber 300 may include a gas circulation system comprising a gas circulation fan, which may be, e.g., a generally cylindrical crossblower fan 330. The cross blower fan 330 serves to drive gas within the interior of the discharge chamber 300, generally in a circular fashion as described below, in order to remove gas that contains ionized particles and debris and is depleted of, e.g., F2 from the discharge region between successive gas discharges, and thus to replenish the discharge region with fresh gas before and in preparation for the next gas discharge.

[0042] The cross blower fan 330 includes an impeller 331 made up of an arrangement of forward- curved blades 332 mounted on a central shaft 333. The orientation of the shaft 333 of the cross flow blower is horizontal in the figure. The blades 332 rotate together in a direction that is clockwise in the orientation of FIG. 3 as shown by the arrow A. This defines an intake region 375 in the lower portion of the arrangement as oriented in the figure and an exhaust region 377 in the upper part of the arrangement as oriented in the figure of gas flow as indicated by the arrow B. A top surface 327 of the lower insulator 325 defines a vortex wall 329 for cross blower fan 330 while the part of the chamber wall 305 adjacent a lower portion of the cross blower fan 330 defines a rear wall 340 for the cross blower fan 330. The arrangement shown in FIG. 3 also includes one or more heat exchangers 350 which extract heat from the gas circulating in the discharge chamber 300, one of the primary sources of heat being the motor for the cross flow blower fan 330.

[0043] Cross flow blowers are a form of radial fan in which the gas flows around the transverse length of the axis of rotation in the same manner that water flows past a waterwheel. One technical issue arising from the use of a cross flow blower is that these fans are relatively inefficient, i.e., they have a low thrust-to-power ratio. This is due to the fact that only one half segment of the fan is moving gas into the gap while the other segment is working against the flow, thus being slowed down by incoming gas. Thus, these fans have only a limited gas clearing ratio, i.e., the ratio of spent gas to fresh gas in the mixture of gases in the discharge region. As a result the cross flow blower imposes limitations on reaching higher pulse repetition rates because the higher repetition rates leave less time for clearing and replenishing the gases in the discharge region between pulses.

[0044] According to an aspect of an embodiment, to address this technical challenge, an axial turbine is used instead of a cross flow blower to circulate gas through the discharge region. An axial turbine or compressor is a turbine in which the flow of the fluid is parallel to the axis of rotation of the impeller. In other words the gas moves in a direction parallel to shaft of the impeller. These axial turbines are very efficient and offer the potential for greater continuous pressure increases.

[0045] According to another aspect of an embodiment the impeller of the axial turbine is driven by at least one motor magnetically coupled to one axial end of the impeller shaft. The arrangement may also include another motor, with the other motor being magnetically coupled to the other to the other end of the impeller shaft. Magnetically coupling permits the motor or motors to be positioned wholly outside of and isolated from the flow of gas.

[0046] According to another aspect of an embodiment the use of an axial turbine provides greater flexibility as to the design and placement of the heat exchangers. The heat exchangers may be generatively designed and 3D printed to optimize flow shape and heat transfer.

[0047] FIG. 4 is a diagram of a discharge chamber 400 in fluid communication with a gas replenishment system 405 in accordance with an aspect of an embodiment. Here and elsewhere, “in fluid communication” means that there is a path for a fluid such as a gas to flow. As can be seen, the discharge chamber 400 includes a cathode 410 and an anode 420 with a discharge region 417 between them. The cathode 410 is secured by a main insulator 415 while the anode 420 is secured by an anode support 425.

[0048] Gas flows through the discharge region 417 as indicated by the arrow B. An exhaust port 430 is disposed at a position downstream from the discharge region 417. A conduit section 435 coupled to the exhaust port 430 by a flange 432. Gas flows from the discharge chamber 400 through the discharge region 417 and out of the discharge chamber 400 through the exhaust port 430. In the conduit section 435 the gas flows in the direction indicated by the arrows C and D.

[0049] The conduit section 435 is coupled to another conduit section 440 by a pair of flanges 437, 439. In the conduit section 440 the gas flows in the direction indicated by the arrow E. It will be understood that it is not strictly necessary for there to be separate conduit sections and that instead the recirculation path could simply be a single piece of conduit. An advantage of having separate sections, however, is that it facilitates fabrication of the gas replenishment system using additive / subtractive hybrid manufacturing techniques such as metal 3D printing / machining hybrid processes.

[0050] The conduit section 440 is connected to a conduit section 470 by flanges 452 and 454. The conduit section 470 houses an axial flow turbine 450 which includes a shaft 455 and an impeller 457 having blades 459. The axial flow turbine 450 also includes a motor 460 coupled to the portion of the shaft 455 which is upstream (vertically below in the orientation shown in the figure) of the impeller 457 and another motor 465 which is downstream (vertically above in the orientation shown in the figure) of the impeller 457. As shown, the motor 460 is coupled to shaft 455 by a magnetic coupler 462 and motor 465 is coupled to shaft 455 by a magnetic coupler 467. As explained more fully below in connection with FIG. 6, the use of magnetic couplers permits positioning of the motors outside of the conduit where they are not exposed to the corrosive effects of the lasing gas.

[0051] In the conduit section 470 the axial flow turbine 450 causes the gas to flow in the direction indicated by the arrow F. The conduit section 470 is connected to an inlet port 480 of the discharge chamber 400 by flange 472. This completes a recirculation path which replenishes gas in the discharge region 417 in the discharge chamber 400 by continuously replacing the gas in the discharge region with gas in the conduit.

[0052] FIG. 5 is a perspective view of a combination of a discharge chamber 400 and a gas replenishment system 405 in accordance with another aspect of an embodiment. The embodiment of FIG. 5 includes a recess 500 which is positioned to accommodate a combination of a motor andmagnetic coupler driving the impeller of the axial flow turbine. When a second motor is used a matching recess, visible in FIG. 6, is positioned vertically below the recess 500 in the orientation shown in the figure.

[0053] One of ordinary skill in the art will appreciate that it is possible to have arrangements which do not have such recesses. For example, the motor or motors could be placed on the exterior of the conduit and longer magnetic couplings could be used. These recesses permit the motors to be mechanically coupled to the impeller of the axial flow turbine without exposing the motors to the corrosive lasing gases circulating in the conduits.

[0054] FIG. 6 is a partially cutaway view of the embodiment depicted in FIG. 5. As can be seen in FIG. 6, the conduit section 470 houses the axial flow turbine 450. The impeller 457 of the axial flow turbine 450 with its blades 459 is housed in the interior of the conduit 470. The impeller 457 is mechanically coupled to a shaft 455 which is in turn coupled to two motors, one motor being motor 460 by a magnetic coupler 462 and the other motor being motor 465 by a magnetic coupler 467. As shown, the motor 465 is located in recess 500 where it is not exposed to the corrosive lasing gas travelling in the conduits. Similarly, the motor 460 is located in a recess 510 which is also an area which is not subjected to the corrosive lasing gas.

[0055] As mentioned, one of ordinary skill in the art will appreciate that while the described example of an arrangement has two motors other arrangements may use only a single motor or more than two motors.

[0056] According to another aspect of an embodiment, a heat exchanger / flow homogenizer is placed in the conduit section just upstream of the inlet port 480 as shown in FIG. 7A. A heat exchanger is desirable in implementations in which it is desired to remove heat from the gas before the gas is introduced into the discharge region. The heat may have been added to the gas, for example, by the motor of the axial flow turbine 450. A homogenizer is desirable because the gas in the conduit 470 passes from a relatively large aperture in the vicinity of the axial flow turbine 450 to a narrow and long aperture at the inlet port 480, and it is desirable to homogenize the flow of gas before it reaches the discharge region. Herein, “homogenize” means to make the gas molecule velocity distribution relatively uniform across a cross section of the discharge region. A homogenizer is a structure which performs that function.

[0057] As shown in FIG. 7 A the heat exchanger / flow homogenizer 600 can be implemented as an insert that is placed inside the conduit section 470. It should be notes that the heat exchanger / flow homogenizer 600 may be placed in any portion of the conduit or conduit system that recirculates gas to the discharge chamber 400 as long as the gas remains cooler and homogenized while flowing between the heat exchanger / flow homogenizer 600 and the discharge chamber 400. It is also possible to fabricate the conduit 470 with an integral heat exchanger / flow homogenizer 600. The heat exchanger / flow homogenizer 600 includes a group of fins 610 extending in the stream wise direction (in the zdirection as oriented in the figure) which are arranged to extract heat from the gas as the gas flows past the fin and through the discharge chamber inlet port 480.

[0058] As seen more clearly in FIG. 7B, the heat exchanger / flow homogenizer 600 may be embodied as an array of gas flow channels 620 separated by fins 610. A coolant circulates through the array of fins 610 in an efficient heat exchanging surface geometry (not necessarily serpentine) flowing into the fins 610 through a coolant inlet 630 and leaving the array of fins 610 through a coolant outlet 640. In some implementations, the fins 610 extend to the complete lateral (stream wise) extent of the heat exchanger / flow homogenizer 600. Any suitable fluid may be used as a coolant, for example, water. The gas is cooled as it flows through the gas flow channels 620. The gas flow channels 620 also cause the velocity profile of the gas flow to become more uniform, i.e., homogenized.

[0059] The implementation of the heat exchanger / flow homogenizer 600 shown in FIGS. 7A and 7B is one example of one possible configuration for the heat exchanger / flow homogenizer 600. It will be apparent to one of ordinary skill in the art that a different arrangement of fins 610 may be used. The fins 610 may be straight as shown in FIG. 7B, or they may be curved. The fins 610 may be arranged in a regular array such as shown in FIG. 7B, or they can be arranged with respect to one another in a different arrangement. For example, the widths of the gas flow channels 620 may vary depending on their lateral position (in the x direction as oriented in the figure). The fins 610 may be interconnected in the serpentine manner shown in FIG. 7B, or they may be interconnected in a different manner. In general, the design parameters of the fins 610 and the gas flow channels 620 including their sizes, spacings and shapes will be selected to optimize heat extraction and flow homogenization in the volume of space allotted to them. Generative design, i.e., computer-aided design using artificial intelligence, may be used to optimize the design process.

[0060] As mentioned, the conduit section 470 may be fabricated using additive / subtractive manufacturing techniques such as 3D printing / machining. The heat exchanger / flow homogenizer 600 may also be fabricated using additive manufacturing techniques. Again, generative design may be used to optimize the process of designing the conduits and the heat exchanger / flow homogenizer.

[0061] According to another aspect of an embodiment, the heat exchanger is generatively designed and manufactured using additive / subtractive manufacturing techniques such as 3D printing / machining to optimize flow shape and heat transfer. Generative design here refers to a computer-aided design (CAD) technique that uses artificial intelligence (Al) to optimize the design process.

[0062] Some of the above description is in terms of functional block diagrams with some functions allocated to some blocks and other functions allocated to other blocks. It will be understood that the division between blocks and the allocations are arbitrary and that different divisions and allocations are possible so long as the overall functions are carried out as described above.

[0063] The above description includes examples of multiple embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for each of these embodiments, but one of ordinary skill in the art may recognize that many further combinations andpermutations of elements of the various embodiments are possible based on the disclosure. Accordingly, the described embodiments are intended to be representative of and encompass all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims.

[0064] Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is construed when employed as a transitional word in a claim. Also, although elements of the described aspects and / or embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. Additionally, all or a portion of any aspect and / or embodiment may be utilized with all or a portion of any other aspect and / or embodiment, unless stated otherwise.

[0065] Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract, and drawings may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0066] Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a subcombination.

[0067] Moreover, while operations may be depicted in the drawings or described in the specification in a particular order, such operations need not be performed in the particular order shown or in sequential order, or that all operations be performed, to achieve desirable results. Other operations that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated and / or disclosed may differ from those shown in the figures. Depending on the embodiment, certain of the steps described above may be removed, others may be added.

[0068] Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products.

[0069] For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

[0070] Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and / or steps. Thus, such conditional language is not generally intended to imply that features, elements, and / or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and / or steps are included or are to be performed in any particular embodiment.

[0071] Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.

[0072] Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5 % of, within less than 1% of, within less than 0.1 % of, and within less than 0.01 % of the stated amount. As another example, in certain embodiments, the terms “generally parallel” and “substantially parallel” refer to a value, amount, or characteristic that departs from exactly parallel by less than or equal to 15 degrees, 10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree.

[0073] The scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive.

[0074] The implementations can be further described using the following clauses.1. A gas replenishment system for a discharge chamber for a deep ultraviolet laser, the gas replenishment system comprising: a discharge chamber enclosure; a gas conduit having a first port arranged to introduce gas into the discharge chamber enclosure and a second port arranged to exhaust gas from the discharge chamber enclosure; and an axial flow turbine positioned in the gas conduit, the axial flow turbine having an axial shaft and a plurality of blades attached radially to the axial shaft with the axial shaft being arranged to be parallel to a flow of gas through the axial flow turbine.2. The gas replenishment system of clause 1 further comprising a motor coupled to the axial shaft.3. The gas replenishment system of clause 2 further comprising a magnetic coupler arranged to magnetically couple rotational force from the motor to the axial shaft.4. The gas replenishment system of clause 2 further comprising a second motor coupled to the axial shaft.5. The gas replenishment system of clause 4 further comprising a second magnetic coupler arranged to magnetically couple rotational force from the second motor to the axial shaft.6. The gas replenishment system of clause 2 wherein the motor is positioned outside of the gas conduit and the discharge chamber enclosure.7. The gas replenishment system of clause 1 further comprising at least one heat exchanger arranged to extract heat from the gas in the gas conduit.8. The gas replenishment system of clause 1 further comprising a heat exchanger positioned in the gas conduit between the axial flow turbine and the first port.9. The gas replenishment system of clause 1 further comprising a flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.10. The gas replenishment system of clause 1 further comprising a combined heat exchanger and flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.11. A gas replenishment system for a discharge chamber for a deep ultraviolet laser, the gas replenishment system comprising: a gas conduit having a first port adapted to be connected to the discharge chamber to introduce gas into the discharge chamber and a second port adapted to be connected to the discharge chamber to exhaust gas from the discharge chamber; and an axial flow turbine positioned in the gas conduit, the axial flow turbine having an axial shaft and a plurality of blades attached radially to the axial shaft with the axial shaft being arranged to be parallel to a flow of gas through the axial flow turbine.12. The gas replenishment system of clause 11 further comprising a motor coupled to the axial shaft.13. The gas replenishment system of clause 12 wherein the motor is positioned outside of the gas conduit.14. The gas replenishment system of clause 12 further comprising a magnetic coupler arranged to magnetically couple rotational force from the motor to the shaft.15. The gas replenishment system of clause 11 further comprising a heat exchanger positioned in the gas conduit between the axial flow turbine and the first port.16. The gas replenishment system of clause 11 further comprising a flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.17. The gas replenishment system of clause 11 further comprising a combined heat exchanger and flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.18. A gas replenishment system for a discharge chamber for a deep ultraviolet laser, the gas replenishment system comprising: a gas conduit having a first port adapted to be connected to the discharge chamber to introduce gas into the discharge chamber and a second port adapted to be connected to the discharge chamber to exhaust gas from the discharge chamber to circulate the gas through the discharge chamber, the gas conduit establishing a gas return path that does not pass through the discharge chamber; and an axial flow turbine positioned in the gas conduit, the axial flow turbine having an axial shaft and an impeller comprising a plurality of blades attached radially to the axial shaft to have an axis of rotation coinciding with the axial shaft with the axis of rotation being arranged to be parallel to a flow of gas through the impeller, the axial flow turbine being arranged to accelerate the gas in an axial direction towards the first port.19. The gas replenishment system of clause 18 further comprising a motor coupled to the axial shaft.20. The gas replenishment system of clause 19 wherein the motor is positioned outside of the gas conduit.21. The gas replenishment system of clause 19 further comprising a magnetic coupler arranged to magnetically couple rotational force from the motor to the shaft.22. The gas replenishment system of clause 18 further comprising a heat exchanger positioned in the gas conduit between the axial flow turbine and the first port.23. The gas replenishment system of clause 18 further comprising a flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.24. The gas replenishment system of clause 18 further comprising a combined heat exchanger and flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.

[0075] The above-described implementations and other implementations are within the scope of the following claims.

Claims

CLAIMS1. A gas replenishment system for a discharge chamber for a deep ultraviolet laser, the gas replenishment system comprising: a discharge chamber enclosure; a gas conduit having a first port arranged to introduce gas into the discharge chamber enclosure and a second port arranged to exhaust gas from the discharge chamber enclosure; and an axial flow turbine positioned in the gas conduit, the axial flow turbine having an axial shaft and a plurality of blades attached radially to the axial shaft with the axial shaft being arranged to be parallel to a flow of gas through the axial flow turbine.

2. The gas replenishment system of claim 1 further comprising a motor coupled to the axial shaft, and a magnetic coupler arranged to magnetically couple rotational force from the motor to the axial shaft.

3. The gas replenishment system of claim 2 further comprising a second motor coupled to the axial shaft, and a second magnetic coupler arranged to magnetically couple rotational force from the second motor to the axial shaft.

4. The gas replenishment system of claim 2 wherein the motor is positioned outside of the gas conduit and the discharge chamber enclosure.

5. The gas replenishment system of claim 1 further comprising at least one heat exchanger arranged to extract heat from the gas in the gas conduit.

6. The gas replenishment system of claim 1 further comprising a heat exchanger positioned in the gas conduit between the axial flow turbine and the first port.

7. The gas replenishment system of claim 1 further comprising a flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.

8. The gas replenishment system of claim 1 further comprising a combined heat exchanger and flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.

9. A gas replenishment system for a discharge chamber for a deep ultraviolet laser, the gas replenishment system comprising: a gas conduit having a first port adapted to be connected to the discharge chamber to introduce gas into the discharge chamber and a second port adapted to be connected to the discharge chamber to exhaust gas from the discharge chamber; and an axial flow turbine positioned in the gas conduit, the axial flow turbine having an axial shaft and a plurality of blades attached radially to the axial shaft with the axial shaft being arranged to be parallel to a flow of gas through the axial flow turbine.

10. The gas replenishment system of claim 9 further comprising a motor coupled to the axial shaft, wherein the motor is positioned outside of the gas conduit.

11. The gas replenishment system of claim 9 further comprising a motor coupled to the axial shaft, and a magnetic coupler arranged to magnetically couple rotational force from the motor to the shaft.

12. The gas replenishment system of claim 9 further comprising a heat exchanger positioned in the gas conduit between the axial flow turbine and the first port.

13. The gas replenishment system of claim 9 further comprising a flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.

14. The gas replenishment system of claim 9 further comprising a combined heat exchanger and flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.

15. A gas replenishment system for a discharge chamber for a deep ultraviolet laser, the gas replenishment system comprising: a gas conduit having a first port adapted to be connected to the discharge chamber to introduce gas into the discharge chamber and a second port adapted to be connected to the discharge chamber to exhaust gas from the discharge chamber to circulate the gas through the discharge chamber, the gas conduit establishing a gas return path that does not pass through the discharge chamber; and an axial flow turbine positioned in the gas conduit, the axial flow turbine having an axial shaft and an impeller comprising a plurality of blades attached radially to the axial shaft to have an axis of rotation coinciding with the axial shaft with the axis of rotation being arranged to be parallel to a flow of gas through the impeller, the axial flow turbine being arranged to accelerate the gas in an axial direction towards the first port.

16. The gas replenishment system of claim 15 further comprising a motor coupled to the axial shaft, wherein the motor is positioned outside of the gas conduit.

17. The gas replenishment system of claim 15 further comprising a motor coupled to the axial shaft, and a magnetic coupler arranged to magnetically couple rotational force from the motor to the shaft.

18. The gas replenishment system of claim 15 further comprising a flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.

19. The gas replenishment system of claim 15 further comprising a combined heat exchanger and flow homogenizer positioned in the gas conduit between the axial flow turbine and the first port.

Images