System for controlling gas flow in a laser discharge chamber

Abstract

A discharge chamber for use in a deep ultraviolet radiation source in which a cross flow blower is used to refresh lasing gas in a discharge region and a flow block is placed in an intake region of the cross flow blower to reshape the flow profile of the gas entering the cross flow blower. This permits the cross flow blower to operate more efficiently, i.e., offer the same performance while consuming less energy, so that energy consumption can be reduced.

Description

SYSTEM FOR CONTROLLING GASFLOW IN A LASER DISCHARGE CHAMBERCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Application No. 63 / 600,970, filed November 20, 2023, titled SYSTEM FOR CONTROLLING GAS FLOW IN A LASER DISCHARGE CHAMBER, and to U.S. Application No. 63 / 717,062 filed November 6, 2024, titled SYSTEM FOR CONTROLLING GAS FLOW IN A LASER DISCHARGE CHAMBER which are incorporated herein in their entirety by reference.FIELD

[0002] The disclosed subject matter relates to systems for controlling the circulation of gas in a laser discharge chamber such as for a deep ultraviolet (DUV) radiation laser 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 gas in the discharge region between the electrodes becomes depleted of one or more components. Thus a DUV discharge chamber typically includes a cross flow blower to force the gas flow in the discharge chamber. The gas flow replaces the residual gas in the discharge region with fresh gas from elsewhere in the chamber for the next discharge event.

[0006] 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. The amount of energy used by the blower motor imposes a restriction on the overall ability to limit energy consumption. It also posesa major obstacle to increasing the blower speed to achieve a higher gas clearance ratio without a redesign of the blower motor.

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

[0008] The following presents a succinct summary of one or more embodiments in order to promote a basic understanding of the presently disclosed subject matter. This summary is not an extensive overview of all contemplated embodiments and is not intended to identify as key or critical any elements of any embodiments nor delineate the scope of any embodiments. Its sole purpose is to present some concepts relating to the embodiments in a streamlined form as a prelude to the more detailed description that is presented later.

[0009] According to an aspect of an embodiment there is disclosed a discharge chamber for a deep ultraviolet laser, the discharge chamber comprising a chamber enclosure, a cross flow blower positioned in the chamber enclosure, the cross flow blower including an impeller comprising a plurality of impeller blades having outer edges arranged in relation to each other to define an outer circumference of the cross flow blower, and a flow block arranged between the impeller and an interior surface of the chamber enclosure at an intake portion of the cross flow blower. The flow block has a first surface confronting and spaced away from a portion of the outer circumference, the first surface being arc shaped and having a center of curvature coincident with a center of curvature of the outer circumference and a ramp surface arranged to extend from the first surface to a portion of the interior surface of the chamber enclosure.

[0010] The ramp surface may be substantially straight and arranged to extend from the first surface to the portion of the interior surface of the chamber enclosure in a direction and at a position that is an extension of a radius of the outer circumference.

[0011] The flow block may comprise an insert mechanically coupled to the interior surface of the chamber enclosure. The flow block may comprise an integral formation of the chamber enclosure.

[0012] The portion of the interior surface of the chamber enclosure may be substantially straight and the ramp surface of the flow block may form an angle with the portion of the interior surface having a magnitude in a range of about 40 degrees to about 60 degrees. The angle may be substantially equal to about 40 degrees. The angle may be substantially equal to about 58 degrees.

[0013] The flow block may be arranged to partially block inflow to a rear wall portion of the cross flow blower. The flow block may substantially fill a space between the impeller and an interior surface of a wall of the discharge chamber in a region including a rear wall portion of the cross flow blower.

[0014] The discharge chamber may further comprise a second flow block arranged to form a vortex wall for the cross flow blower. The discharge chamber may further comprise a dust collection screen arranged to cover at least a portion of the second surface.

[0015] According to another aspect of an embodiment there is disclosed a discharge chamber assembly comprising a discharge chamber, a cross flow blower configured to circulate gas through the discharge chamber, the cross flow blower and the discharge chamber configured to create an intake region where gas enters the cross flow blower and an exhaust region where gas exits the blower a first flow block positioned in a portion of the intake region to restrict the gas from entering the cross flow blower at a rear wall area of the cross flow blower, and a second flow block arranged to channel gas in the exhaust region of the cross flow blower and defining a vortex wall of the cross flow blower.

[0016] At least a portion of a surface of the discharge chamber adjacent the intake region may be straight and the first flow block may have a ramp portion intersecting with the portion of the surface of the discharge chamber at an angle having a magnitude in a range of about 40 degrees to about 60 degrees. The angle may be substantially equal to about 40 degrees. The angle may be substantially equal to about 58 degrees.

[0017] The first flow block may comprise an insert mechanically coupled to the interior surface of the discharge chamber. The first flow block may comprise an integral formation in the interior surface of the discharge chamber.

[0018] The discharge chamber assembly may further comprise a dust collection screen arranged to cover at least a portion of a surface of the first flow block.

[0019] According to another aspect of an embodiment there is disclosed a discharge chamber for a deep ultraviolet laser, the discharge chamber comprising a chamber enclosure having a substantially flat bottom surface, a cross flow blower positioned in the chamber enclosure, the cross flow blower including a plurality of impeller blades the outer edges of which together define an outer circumference of the cross flow blower, and a flow block arranged between the impeller and the substantially flat bottom surface of the chamber enclosure at an intake portion of the cross flow blower. The flow block has a first surface conforming to and spaced away from a bottom portion of the outer circumference of the cross flow blower, and a ramp surface arranged to extend from the first surface to the substantially flat bottom surface of the chamber enclosure.

[0020] The ramp surface may be substantially straight and arranged to extend from the first surface to the substantially flat bottom surface of the chamber enclosure in a direction and at a position that is an extension of a radius of the outer circumference of the cross flow blower.

[0021] According to another aspect of an embodiment there is disclosed a discharge chamber for a deep ultraviolet laser, the discharge chamber comprising a chamber enclosure having a top wall adjacent to a discharge area, a bottom wall arranged opposed to the top wall, a first side wall, and a second side wall, a cross flow blower positioned in the chamber enclosure adjacent to the first side wall, the crossflow blower including an impeller comprising a plurality of impeller blades having outer edges arranged in relation to each other to define a circular outer circumference of the cross flow blower, and a flow block arranged at a corner of the first side wall and the bottom wall between the impeller and the bottom wall at an intake portion of the cross flow blower, the flow block having a first surface facing, spaced away from, and conforming to a portion of the outer circumference.

[0022] The flow block may further comprise a ramp surface arranged to extend from the first surface towards a portion of the bottom wall. The flow block may substantially fill a volume bounded by the portion of the outer circumference, a portion of the bottom wall, a corner at which the first side wall and the bottom wall meet, portions of the first side wall and the bottom wall adjacent to the corner, and the ramp surface.

[0023] The discharge chamber may further comprise a dust collection screen arranged to cover at least a portion of an interior surface of at least one of the bottom wall, the second side wall, and the ramp surface. The dust collection screen may comprise a plurality of layers of wire mesh. At least some of the layers of wire mesh may be nonplanar. At least some of the layers of wire mesh may be corrugated.

[0024] The flow block may be spaced away from bottom wall and define an upper and side surface of an open volume further defined by a corner at which the first side wall and the bottom wall meet and portions of the first side wall and the bottom wall adjacent to the corner. Then the discharge chamber may further comprise a dust collection screen arranged to cover at least a portion of an interior surface of at least one of the bottom wall and the second side wall. The discharge chamber of may further comprise an angled dust collection screen extending from the bottom wall to an edge of the flow block. The dust collection screen may comprise a plurality of layers of wire mesh. At least some of the layers of wire mesh may be nonplanar. At least some of the layers of wire mesh may be corrugated.

[0025] The ramp surface may be arranged to extend from the arcuate first surface towards the portion of the bottom wall and is slanted at a first angle towards the first side wall with respect to an extension of a radius of the circular outer circumference. The discharge chamber may further comprise a dust collection screen arranged to cover at least a portion of an interior surface of at least one of the bottom wall, the second side wall, and the ramp surface. The dust collection screen may comprise a plurality of layers of wire mesh. At least some of the layers of wire mesh may be nonplanar. At least some of the layers of wire mesh may be corrugated.

[0026] 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

[0027] 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.

[0028] FIG. 1 is a functional block diagram of an overall broad conception of a photolithography system.

[0029] FIG. 2 is a functional block diagram of an overall broad conception of an illumination system such as might be used in the photolithography system of FIG. 1.

[0030] FIG. 3 is a cross-sectional diagram of a discharge chamber for a DUV radiation source according to an aspect of an embodiment.

[0031] FIG. 4 is a cross-sectional diagram of a discharge chamber for a DUV radiation source according to an aspect of an embodiment.

[0032] FIG. 5 is a perspective view of a flow block insert such as might be used in accordance with an aspect of an embodiment.

[0033] FIGS. 6A - 6F are cross sections of embodiments of flow blocks in accordance with aspects of embodiments.

[0034] FIG. 7 is a cross-sectional diagram of a discharge chamber for a DUV radiation source according to an aspect of an embodiment.

[0035] FIG. 8 is a cross-sectional diagram of a discharge chamber for a DUV radiation source according to an aspect of an embodiment.

[0036] FIG. 9 is a cross-sectional diagram of a discharge chamber for a DUV radiation source according to an aspect of an embodiment.

[0037] FIG. 10 is a cross-sectional diagram of a discharge chamber for a DUV radiation source according to an aspect of an embodiment.

[0038] FIG. 11 A is a perspective view of a flow block according to an aspect of an embodiment.

[0039] FIG. 1 IB is a perspective view of a flow block according to an aspect of an embodiment.

[0040] FIG. 12 is a cross-sectional diagram of a discharge chamber for a DUV radiation source according to an aspect of an embodiment.

[0041] FIG. 13 is a cross-sectional diagram of a discharge chamber for a DUV radiation source according to an aspect of an embodiment.

[0042] FIG. 14 is a cross-sectional diagram of a discharge chamber for a DUV radiation source according to an aspect of an embodiment.

[0043] FIG. 15 A is a plan view of a wire mesh screen such as could be used in a dust collection screen.

[0044] FIG. 15B is a side view of a stack of wire mesh screens such as could be used in a dust collection screen.

[0045] FIG. 16A is a side view of a dust collection screen according to an aspect of an embodiment.

[0046] FIG. 16B is a side view of a dust collection screen according to an aspect of an embodiment.

[0047] FIG. 16C is a side view of a dust collection screen according to an aspect of an embodiment.

[0048] FIG. 17 is a side view of a dust collection screen according to an aspect of an embodiment.

[0049] FIG. 18 is a side view of a dust collection screen according to an aspect of an embodiment.

[0050] Further features and advantages of the presently disclosed subject matter, as well as the structure and operation of various embodiments of the presently disclosed subject matter, are described in detail below with reference to the accompanying drawings. 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

[0051] 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, for purposes of explanation, numerous 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 any embodiment described below can be practiced without adopting the specific design details associated with it.

[0052] Systems such as those described herein may render benefits in a wide range of applications and implementations. For the sake of having a specific nonlimiting example to facilitate description, one such application is in semiconductor photolithography. 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 the wafer 120 and connected to a positioner 130 configured to accurately position the wafer 120 in accordance with certain parameters. The pulsed radiation beam 110 may have a wavelength in the DUV range.

[0053] 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 that optical axis. The objective arrangement includes a projection lens and enables 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. Theillumination system 105 also homogenizes (makes uniform) the intensity distribution of the pulsed radiation beam 110 across the mask.

[0054] 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. The process recipes determine the parameters of the pulsed radiation beam 110 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.

[0055] 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.

[0056] 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 pulsed laser source 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.

[0057] The MO seed laser system 200 may also include a master oscillator output coupler (“MO OC”) 230, which may comprise a partially reflective mirror, and a reflective grating (not shown) in a line narrowing module (“LNM”) 235 disposed on opposite sides of the MO discharge chamber 220. The LNM 235, the MO discharge chamber 220, and the MO OC 230 may form an oscillator cavity 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).

[0058] 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.

[0059] 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 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.

[0060] 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. The lasing gas may be, for example, ArF, KrF, F2, XeF, and / or XeCl. The lasing gas is selected to produce relatively broad band radiation that may be line narrowed to a relatively very narrow linewidth and center wavelength selected in the LNM 235.

[0061] FIG. 3 is a stylized cross-sectional diagram of a discharge chamber 300 according to an aspect of an embodiment. 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 has a chamber wall 305 that encloses an interior volume 307. The discharge chamber 300 contains an upper electrode 310 acting in the example shown as a cathode and a lower electrode 320 acting in the example shown as an anode. It will be understood, however, that this polarity may be reversed. 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 then the electrodes extend in the + / - X direction. One or both of the anode 320 and the cathode 310 may be entirely contained in the pressure envelope of discharge chamber 300 defined by the discharge chamber wall 305 (which may form a body of the chamber) 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.

[0062] An applied voltage supply establishes a voltage gradient between cathode 310 and anode 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 discharge chamber wall 305 of the chamber 300 and so is held at a ground (0) potential. The upper electrode (cathode 310) is charged to a large (for example ~20 kV) negative voltage. This voltage gradient causes discharges in the gas in the gap between the electrodes.

[0063] 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 circulating the gas in the discharge chamber to introduce fresh gas into the discharge region. This is accomplished in the example shown in FIG. 3 through provision of a gas circulationsystem comprising a gas circulation fan, which may be, e.g., a generally cylindrical cross blower fan 330. The cross blower fan 330 serves to move 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.

[0064] The cross blower fan 330 includes an impeller 331 made up of an arrangement of forward- curved blades 332, the outer edges of which define a circle 334 having a center 336. The blades 332 rotate together around the center 336 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. Gas in the intake region 375 is driven by the impeller 311 to the exhaust region 377 and flows as indicated by the arrow B to the discharge region between electrodes 310 and 320. A top surface 327 of the lower insulator 325 defines a vortex wall 329 for cross blower fan 330 while the part of the discharge chamber wall 305 adjacent a lower portion of the cross blower fan 330 defines a rear wall 380 for the cross blower fan 330. As is well known for cross flow or cross blower fans, the vortex wall is a curved structure, located inside the assembly housing the fan, that helps to guide airflow through the fan, ensuring that the airflow follows the desired path from inlet to outlet. It provides a surface against which a secondary vortex forms that helps to stabilize the complex airflow patterns within the fan.

[0065] Also as shown in FIG. 3, in accordance with an aspect of an embodiment a flow block 410 is placed between the impeller 331 of cross blower fan 330 and a portion 306 of the interior of the discharge chamber wall 305 in the intake region of the cross flow blower 330 in order to reshape the flow profile of the gas entering the cross flow blower fan 330. This flow block 410 is positioned in the vicinity of the rear wall 380 and so may be referred to as a rear wall block.

[0066] The flow block 410 has surface 420 facing and spaced away from a portion of the circumference of a circle 334 defined by the ends of the impeller blades 332. The clearance distance between the ends of the impeller blades 332 and the opposing surface 420 of the flow block 410 is in the range of about 0.5 mm to about 5 mm, e.g., about 0.5 mm, 0.75 mm, 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm. In various implementations, the this clearance distance may be a fixed value along the path of the gas flow between impeller blades 332 and surface 420. In other implementations this clearance distance may vary along the path of gas flow. For example, the clearance may be 2 mm at the intake edge adjacent to ramp surface 430, may narrow to 0.75 mm at a location further along the flow path, and may expand to 5mm at a subsequent location near rear wall portion 380. In the example depicted the surface 420 has a circular arc shape with a center of curvature coincident with the center 336 of the circle defined by the outer edges of the impeller blades 332. It will be appreciated, however, that thesurface 420 may have a different shape including curved or straight and that when the surface 420 is an arc its radius of curvature is not necessarily coincident with the center 336.

[0067] The flow block 410 also has a ramp surface 430 contiguous with the surface 420 and arranged to extend from the circumference of the circle 334 defined by the outer edges of the impeller blades 332 to the portion of the interior surface 306 of the discharge chamber wall 305 in a direction and at a position that is an extension of a radius of the circle 334 as shown in FIG. 3. It will be understood, however, that the ramp surface 430 may extend in a direction that is not an extension of a radius of the circle 334. In some embodiments, ramp surface 430 may form an angle c|) with the portion of the interior surface 306 in a range of about 40 degrees to about 60 degrees, for example, the angle may be substantially equal to about 40 degrees or to about 58 degrees. The angle c|) is the complement of the angle 0 which is the angle the ramp surface 430 forms with a line orthogonal to the horizonal (in the figure) portion of the interior surface 306.

[0068] According to another aspect of an embodiment, as shown in FIG. 3, the flow block 410 may substantially fill a space between the impeller 331 and the interior surface 306 of the discharge chamber wall 305 in the intake region, with a configuration of a surface of the flow block 410 conforming to the shape of the portion of the interior surface 306 of the discharge chamber wall 305. For example, the corner 440 of the flow block 410 may be shaped to complement the shape of a corner of the interior surface 306.

[0069] In the embodiment of FIG. 3 the flow block 410 is implemented as an insert mechanically coupled to the interior of the discharge chamber by any suitable means such as screws 445. This implementation has the advantage of enabling retrofitting of deployed discharge chambers. One of ordinary skill in the art will appreciate, however, that it is not necessary that the flow block be an insert and that instead the flow block could be implemented in whole or in part as an integral feature 510 of an interior surface 506 of a discharge chamber 500. An embodiment having this feature is shown in FIG. 4, which is a stylized cross-sectional diagram of a discharge chamber 500 according to an aspect of an embodiment. As shown in FIG. 4, in accordance with an aspect of an embodiment a flow block in the form of an integral feature 510 is positioned between the impeller 331 of cross blower fan 330 and a portion 506 of the interior of the discharge chamber wall 305 in order to reshape the flow profile of the gas entering the cross flow blower fan 330. This feature 510 may also be referred to as a rear wall block.

[0070] According to an aspect of an embodiment the feature 510 is positioned between the impeller 331 and an interior surface 506 of the discharge chamber enclosure in the intake region of the cross flow blower 330. The feature 510 has a surface 520 confronting and spaced away from a portion of the circle 334 defined by the outer edges of the impeller blades 332. In the example depicted the surface 520 is curved with a circular arc shape having a center of curvature coincident with the center 336 ofthe circle 334. It will be appreciated, however, that the surface 520 may have a different shape and that when the surface 520 is circular its radius of curvature is not necessarily coincident with the center 336.

[0071] The feature 510 also has a ramp surface 530 contiguous with the surface 520 and arranged to extend from the circle defined by the outer edges of the impeller blades 332 to the portion of the interior surface 506 of the chamber wall 505 in a direction and at a position that is an extension of a radius of the circle 334. It will be understood, however, that the ramp surface 430 may extend in a direction that is not an extension of a radius of the circle 334. In some embodiments, the ramp surface 520 of the feature 510 may form an angle c|) with the portion of the interior surface in a range of about 40 degrees to about 60 degrees, for example, the angle may be substantially equal to about 40 degrees or to about 58 degrees. The angle c|) is the complement of the angle 0 which is the angle the straight portion forms with a line orthogonal to the portion of the interior surface.

[0072] According to another aspect of an embodiment, as shown in FIG. 4, the feature 510 may substantially fill a space between the impeller 331 and the interior surface 506 of the discharge chamber wall 505 in the intake region.

[0073] FIG. 5 is a perspective view of the flow block 410 showing the surface 420, the ramp surface 430, and the corner 440. As can be seen, the flow block 410 extends in the X direction in the orientation shown in the figure. In the example shown the flow block is dimensioned to be substantially longitudinally coextensive with the cross flow blower 330 (FIG. 4). One of ordinary skill in the art will appreciate, however, that the longitudinal extent of the flow block 410 may be greater or less than that of the cross flow blower 330.

[0074] As shown in FIG. 6 A and described above, one embodiment of a flow block 410 includes an arc-shaped upper surface 420 facing the outer circumference of the cross flow blower. The embodiment of the flow block 410 also has a straight ramp section 430 extending downwardly and right (in the figure) in a radial direction. One of ordinary skill in the art will appreciate that other configurations for the flow block are possible. For example, as shown in FIG. 6B, the upper surface 615 of a flow of structure 610 has a curve which is not circular. Also, the ramp surface 616 extending in the downward direction in the figure is curved rather than straight. As shown in FIG. 6C, a flow block 620 may have an upper surface 625 that is straight and a downwardly extending surface which is straight. Also, the flow block 620 of FIG. 6C does not extend as far laterally as do the embodiments of FIG. 6A and FIG. 6B.

[0075] According to an aspect of an embodiment, the upper surface 420 is spaced away from the circle 334 defined by the outer circumference of the cross flow blower, and has a curvature which conforms to, i.e., has a similar shape to, the circle 334 so that there is a gap between the upper surface 420 and the circle 334 having a generally uniform width. This can be achieved, for example, by making the curvature of the upper surface 420 circular with a radius of curvature r matching the radius ofcurvature of the circle 334 defined by the outer circumference of the cross flow blower and by spacing the upper surface 420 radially from the circle 334.

[0076] As shown in FIG. 6D, the upper surface 635 of a flow block 630 may have one portion which is straight and another portion which is curved. Also, the downwardly extended portion 636 may have a positive curve that is, be convex rather than concave with respect to the body of the flow block 630. In the embodiment of FIG. 6E, the top surface 645 of the flow block 640 is straight and the downwardly extending ramp surface 646 is concave with respect to the body of the flow block 640. In the flow block 650 of FIG. 6F, a left hand portion, as depicted in the figure, of a top surface 655 of the flow block 650 is curved but then joins with a straight section. In the embodiment of FIG. 6F, the flow block 650 also has a straight downwardly extending ramp surface 656.

[0077] Other configurations are possible. In general, the configuration of the cross section of the flow block will be selected according to the needs of the application. Also, as indicated above, any of these flow blocks can be implemented as either an insert or may be an integral part of the interior wall of the discharge chamber.

[0078] Also, in the embodiments described above, the cross section of the flow block is uniform along the length of the flow block. It will be apparent to one of ordinary skill in the art, however, that in some instances there may be advantages to vary the cross section of the flow block so that the flow block will have a first cross section at a first longitudinal location and a second, different cross section at a second longitudinal position, and so on. The transitions between the cross sections may be continuous, that is, changing smoothly from one cross section to another, or discontinuous, that is, changing abruptly from one cross section to another.

[0079] According to another aspect of an embodiment, a dust collection screen 700 may be placed on the surface of the ramp portion 730 as shown in FIG. 7. The use of dust collection screens in a discharge chamber is disclosed, for example, in U.S. Patent No. 7,522,650, issued April 21, 2009, and titled “Gas Discharge Laser Chamber Improvements,” the specification of which is incorporated by reference herein. As shown, the surface of the ramp portion 730 may be provided with indentations which form dust collection pockets. Other interior surfaces of the discharge chamber may also be provided with a screen and with indentations such as screen 710 and surface 720.

[0080] As described, the flow block 410 is arranged to partially block inflow to the rear wall portion 380 of the cross flow blower 330. Also, the upper surface of the lower insulator 325 may be regarded as a second flow block. The flow block 410 configured and positioned as shown in the embodiments presented above reshapes the flow profile of the gas entering the cross flow blower.

[0081] As described above, a DUV discharge chamber uses cross flow blowers to drive a flow of gas through the chamber. The gas flow purges the discharge residuals from the electrode gap for the next discharge event. According to an aspect of an embodiment, a flow block is added beneath the blower fan to help reduce the amount of blower current needed for effective operation and save energy. Theflow block substantially, i.e., mostly but not necessarily entirely, fills the volume space between the cross flow blower and the bottom wall of the discharge chamber, thus taking up part of the surface area of the bottom wall. This renders that portion of the bottom unavailable for placement of dust collection screens. It also potentially compromises the effectiveness of the system’s dust management capability which can affect other system components such as the metal fluoride trap and windows permitting visual inspection of processes occurring in the chamber as they become contaminated by dust. Eventually the reduced effectiveness of the dust management system may impact the lifetime of the chamber.

[0082] According to an aspect of an embodiment the flow block and / or the dust collection screens are modified to compensate for any potential losses of dust trapping capability without significant impact to the flow block functionality

[0083] Thus, in some embodiments the flow insert is designed so that it does not entirely fill the volume of space between the cross flow blower and the bottom wall of the discharge chamber, thus making more of the bottom wall available to accommodate a dust collection screen. The flow block has a hollow cavity and the flow block is arranged so that there is an open flow channel between the cross flow blower rear wall and the flow block and another open flow channel between the end of the ramp on flow block and the bottom wall. Although vortices may form in the open space defined by the cavity they have less of an effect on the efficiency of the cross flow blower than vortices which form when there is no flow block at all. In such an arrangement the dust collection screens may be placed on any or all of the bottom wall, side wall, and upper ramp surface.

[0084] In another embodiment the flow block is not provided with a ramp and instead is an element that is spaced away from and conforms to the bottom of the cross flow blower. In other words an open cavity is formed in the flow block and the portion of the flow block which has a ramp in other embodiments is instead left open. Again, although vortices may form in the open space defined by the open cavity they have less of an effect on the efficiency of the cross flow blower. In such an arrangement the dust collection screens may be placed on either or both the bottom wall and side wall. A dust collection screen may also be placed at the position where the ramp is located in other embodiments.

[0085] In another embodiment the angle of the ramp in a flow block having no cavity is altered to create a gap beneath a dust collection screen placed over the ramp.

[0086] According to another aspect of an embodiment the dust filter screens are not flat, i.e., planar, but are instead nonplanar to increase the amount of surface area available to collect dust. The nonplanar screens may be, e.g., furrowed, ridged, undulated, or corrugated, or some combination of these.

[0087] FIG. 8 shows a discharge chamber 800 in accordance with one aspect of an embodiment. Discharge chamber 800 includes a flow block 810 with an arcuate portion 820 and a ramp portion 830. The flow block 810 does not entirely fill the volume of space 840 between the cross blower fan 330 and the bottom wall of the discharge chamber 800. Instead, a cavity is defined between the arcuate portion 820 of the flow block 810 and the bottom wall of the discharge chamber 800. In addition, an edge ofthe arcuate portion 820 adjacent to the rear wall 380 of the cross blower fan 330 is spaced away from the rear wall 380 to create a channel. Also, an edge of the ramp portion 830 adjacent to the bottom wall of the discharge chamber 800 is spaced away from the bottom wall of the discharge chamber 800 creating another channel. As described in more detail below, the arrangement depicted in FIG. 8 makes more of the bottom wall available for placement of a dust collection screen while still enabling the efficiency improvements provided for by the flow block 810.

[0088] FIG. 9 shows a discharge chamber 850 in accordance with an aspect of an embodiment. Discharge chamber 850 includes a flow block 860 with a curved portion 862 and no ramp portion. The flow block 860 defines a cavity or volume of space 870 between the arcuate portion 862 of the flow block 860 and the bottom wall of the discharge chamber 850. As described in more detail below, the arrangement depicted in FIG. 9 makes more of the bottom wall available for placement of a dust collection screen while still enabling the efficiency improvements provided for by the flow block 860.

[0089] FIG. 11A shows an example the flow block 860 in more detail. The flow block 860 of FIG. 11 A is configured as an insert to be placed into the discharge chamber. One of ordinary skill in the art will appreciate, however, that the flow block 860 can also be configured to be integral with of the walls of the discharge chamber. The flow block 860 as depicted in FIG. 11A has two side elements 864 and 866 for attachment of the flow block 860 to the front and rear walls of the discharge chamber. Also visible in FIG. 11A is the arcuate portion 862. The flow block 860 as depicted in FIG. 11A forms a cavity 870 between the arcuate portion 862 and the bottom wall or floor of the discharge cavity.

[0090] FIG. 10 shows a discharge chamber 900 in accordance with an aspect of an embodiment. Discharge chamber 900 includes a flow block 910 with an arcuate portion and a ramp portion with the flow block 910 substantially filling the space between the cross blower fan 330 and the bottom wall of the discharge chamber 900. Again, “substantially” context means almost entirely or even entirely but not necessarily entirely. In the embodiment of FIG. 10, however, the ramp surface of the flow block 910 does not coincide with an extension of a radius of the cross blower fan 330 as indicated by the dashed line. Instead the ramp surface forms an angle with the radial extension. This makes more of the bottom wall of the discharge chamber 900 available for placement of a dust collection screen. It also allows for the creation of a gap between the ramp surface and a dust collection screen placed adjacent to the ramp surface as described in more detail below.

[0091] FIG. 11B shows an example the flow block 910 in more detail. The flow block 910 of FIG. 1 IB is configured as an insert to be placed into the discharge chamber. One of ordinary skill in the art will appreciate, however, that the flow block 910 can also be configured to be integral with of the walls of the discharge chamber. The flow block 910 as depicted in FIG. 11B has two side elements 914 and 916 for attachment of the flow block 910 to the front and rear walls of the discharge chamber. Also visible in FIG. 1 IB is the arcuate portion 912. The flow block 910 as depicted in FIG. 1 IB also includes a ramp surface 918 that forms a recessed portion.

[0092] FIG. 12 shows a possible arrangement for dust collection screens in a discharge chamber 800 such as depicted in FIG. 8. FIG. 12 shows a dust collection screen 1000 placed on the bottom wall of the discharge chamber 800, a dust collection screen 1010 on one vertical wall of the discharge chamber 800, and a dust collection screen 1020 adjacent to the ramp portion of the flow block 810. One of ordinary skill in the art will appreciate that all three of these dust collection screens may be used or any subset of them may be used. As can be seen, the provision of the cavity 840 makes more of the bottom wall of the discharge chamber 800 available for placement of a dust collection screen.

[0093] FIG. 13 shows a possible arrangement for dust collection screens in a discharge chamber 850 such as depicted in FIG. 9. FIG. 13 shows a dust collection screen 1000 placed on the bottom wall of the discharge chamber 850 and a dust collection screen 1010 on one vertical wall of the discharge chamber 850. FIG. 13 also shows a dust collection screen 1020 arranged to extend from the bottom wall of the discharge chamber 850 towards the cross blower fan 330. One of ordinary skill in the art will appreciate that all three of these dust collection screens may be used or any subset of them may be used. As can be seen, the provision of the cavity 870 makes more of the bottom wall of the discharge chamber 850 available for placement of a dust collection screen.

[0094] FIG. 14 shows a possible arrangement for dust collection screens in a discharge chamber 900 such as depicted in FIG. 10. FIG. 14 shows a dust collection screen 1000 placed on the bottom wall of the discharge chamber 900, a dust collection screen 1010 on one vertical wall of the discharge chamber 900, and a dust collection screen 1020 adjacent to the ramp portion of the flow block 910. One of ordinary skill in the art will appreciate that all three of these dust collection screens may be used or any subset of them may be used. As can be seen, making the angle of the ramp portion of the flow block 910 less shallow makes more of the bottom wall of the discharge chamber 900 available for placement of a dust collection screen. Also, making the angle of the ramp portion of the flow block 910 less shallow allows for a gap between the surface of the ramp portion of the flow block and the dust collection screen 1020 which improves the dust collection capability of the dust collection screen 1020.

[0095] The dust collection screens 1000, 1010, and 1020 may be made up of any suitable type of screen elements including wire mesh screens made of, for example, brass or they may be implemented as another type of screens such as stamped screens. FIG. 15A is a plan view of a wire mesh screen 1050 as an example. As shown in FIG. 15B, several layers of a wire mesh screens can be used to form a dust collection screen 1060. The dust collection screen 1060 is then placed on a surface such as surface 1070 which may be, as described above, one of the walls of the discharge chamber or a surface of a flow block. The dust collection screen 1060 of FIG. 15B shows a dust collection screen made up of four layers but one of ordinary skill in the art that fewer or more layers may be used.

[0096] As mentioned above, the use of a flow block can make less of the interior surfaces of the bottom of the discharge chamber available for placement of dust collection screens. This potentially has a negative impact on the performance of the dust collection screens. In order to mitigate this potentialnegative impact, according to an aspect of an embodiment, the dust collection screens are configured to be nonplanar thus increasing the effective surface area of the dust collection screens available to collect dust. Thus, if the surface of a planar dust collection screen is regarded as extending in an XY plane, the dust collection screens according to these embodiments have surfaces engineered to extend in the Z direction.

[0097] FIG. 16A shows a dust collection screen 1072 in which each layer 1075 is a wire mesh screen having a sawtooth or corrugated configuration. Such a dust collection screen can be configured as shown in 16A. FIG. 16B shows a possible configuration for a dust collection screen 1076 in which flat or planar meshes 1080 and 1085 are placed at the top and bottom of the stack of corrugated wire mesh screens 1075. FIG. 16C shows a possible configuration for a dust collection screen 1077 in which flat or planar meshes 1080 are alternated with corrugated wire mesh screens 1075. One of ordinary skill in the art will appreciate that many combinations of corrugated elements and flat elements can be used to construct the dust collection screen 1076.

[0098] FIGS. 16A-C show nonplanar wire meshes that have a corrugated or sawtooth configuration. As mentioned, other nonplanar configurations are possible such as furrowed, ridged, and undulating configurations. For example, FIG. 17 shows an arrangement in which dust collection screen 1090 is made-up of layers of undulating wire meshes. FIG. 18 shows a dust collection screen 1095 in which the wire meshes have straight vertical portions alternating with straight horizontal portions. One of ordinary skill and art will appreciate that other configurations of nonplanar wire meshes are possible.

[0099] 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.

[0100] 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 and permutations 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] The implementations can be further described using the following clauses.1. A discharge chamber for a deep ultraviolet laser, the discharge chamber comprising: a chamber enclosure: a cross flow blower positioned in the chamber enclosure, the cross flow blower including an impeller comprising a plurality of impeller blades having outer edges arranged in relation to each other to define an outer circumference of the cross flow blower; and a flow block arranged between the impeller and an interior surface of the chamber enclosure at an intake portion of the cross flow blower, the flow block having a first surface facing and spaced away from a portion of the outer circumference, and a ramp surface arranged to extend from the first surface to a portion of the interior surface of the chamber enclosure.2. The discharge chamber of clause 1 wherein the ramp surface is substantially straight and arranged to extend from the first surface to the portion of the interior surface of the chamber enclosure in a direction and at a position that is an extension of a radius of the outer circumference.3. The discharge chamber of clause 1, wherein the flow block comprises an insert mechanically coupled to the interior surface of the chamber enclosure.4. The discharge chamber of clause 1 wherein the flow block comprises an integral formation of the chamber enclosure.5. The discharge chamber of clause 1 wherein the portion of the interior surface of the chamber enclosure is substantially straight and the ramp surface of the flow block forms an angle with the portion of the interior surface having a magnitude in a range of about 40 degrees to about 60 degrees.6. The discharge chamber of clause 5 wherein the angle is substantially equal to about 40 degrees.7. The discharge chamber of clause 5 wherein the angle is substantially equal to about 58 degrees.8. The discharge chamber of clause 1 wherein the flow block is arranged to partially block inflow to a rear wall portion of the cross flow blower.9. The discharge chamber of clause 1 wherein the flow block substantially fills a space between the impeller and an interior surface of a wall of the discharge chamber in a region including a rear wall portion of the cross flow blower.10. The discharge chamber of clause 1 further comprising a second flow block arranged to form a vortex wall for the cross flow blower.11. The discharge chamber of clause 1 further comprising a dust collection screen arranged to cover at least a portion of the second surface.12. A discharge chamber assembly comprising: a discharge chamber; a cross flow blower configured to circulate gas through the discharge chamber, the cross flow blower and the discharge chamber being configured to create an intake region where gas enters the cross flow blower and an exhaust region where gas exits the blower; a first flow block positioned in a portion of the intake region to restrict the gas from entering the cross flow blower at a rear wall area of the cross flow blower; and a second flow block arranged to channel gas in the exhaust region of the cross flow blower and defining a vortex wall of the cross flow blower.13. The discharge chamber assembly as in clause 12 wherein at least a portion of a surface of the discharge chamber adjacent the intake region is straight and wherein the first flow block has a ramp portion intersecting with the portion of the surface of the discharge chamber at an angle having a magnitude in a range of about 40 degrees to about 60 degrees.14. The discharge chamber assembly of clause 13 wherein the angle is substantially equal to about 40 degrees.15. The discharge chamber assembly of clause 13 wherein the angle is substantially equal to about 58 degrees.16. The discharge chamber assembly of clause 12 wherein the first flow block comprises an insert mechanically coupled to the interior surface of the discharge chamber.17. The discharge chamber assembly of clause 12 wherein the first flow block comprises an integral formation in the interior surface of the discharge chamber.The discharge chamber assembly of clause 12 further comprising a dust collection screen arranged to cover at least a portion of a surface of the first flow block. A discharge chamber for a deep ultraviolet laser, the discharge chamber comprising: a chamber enclosure having a substantially flat bottom surface; a cross flow blower positioned in the chamber enclosure, the cross flow blower including a plurality of impeller blades the outer edges of which together define an outer circumference of the cross flow blower; and a flow block arranged between the impeller and the substantially flat bottom surface of the chamber enclosure at an intake portion of the cross flow blower, the flow block having a first surface conforming to and spaced away from a bottom portion of the outer circumference of the cross flow blower, and; and a ramp surface arranged to extend from the first surface to the substantially flat bottom surface of the chamber enclosure. The discharge chamber of clause 19 wherein the ramp surface is substantially straight and arranged to extend from the first surface to the substantially flat bottom surface of the chamber enclosure in a direction and at a position that is an extension of a radius of the outer circumference of the cross flow blower. A discharge chamber for a deep ultraviolet laser, the discharge chamber comprising: a chamber enclosure having a top wall adjacent to a discharge area, a bottom wall arranged opposed to the top wall, a first side wall, and a second side wall; a cross flow blower positioned in the chamber enclosure adjacent to the first side wall, the cross flow blower including an impeller comprising a plurality of impeller blades having outer edges arranged in relation to each other to define a circular outer circumference of the cross flow blower; and a flow block arranged at a corner of the first side wall and the bottom wall between the impeller and the bottom wall at an intake portion of the cross flow blower, the flow block having a first surface facing, spaced away from, and conforming to a portion of the outer circumference. The discharge chamber of clause 21 wherein the flow block further comprises a ramp surface arranged to extend from the first surface towards a portion of the bottom wall. The discharge chamber of clause 22 wherein the flow block substantially fills a volume bounded by the portion of the outer circumference, a portion of the bottom wall, a corner at which the first side wall and the bottom wall meet, portions of the first side wall and the bottom wall adjacent to the corner, and the ramp surface. The discharge chamber of clause 23 further comprising a dust collection screen arranged to cover at least a portion of an interior surface of at least one of the bottom wall, the second side wall, and the ramp surface.25. The discharge chamber of clause 24 wherein the dust collection screen comprises a plurality of layers of wire mesh.26. The discharge chamber of clause 25 wherein at least some of the layers of wire mesh are nonplanar.27. The discharge chamber of clause 26 wherein at least some of the layers of wire mesh are corrugated.28. The discharge chamber of clause 21 wherein flow block is spaced away from the bottom wall and defines an upper and side surface of an open volume further defined by a corner at which the first side wall and the bottom wall meet and portions of the first side wall and the bottom wall adjacent to the corner.29. The discharge chamber of clause 28 further comprising a dust collection screen to cover at least a portion of an interior surface of at least one of the bottom wall and second side wall.30. The discharge chamber of clause 29 further comprising an angled dust collection screen extending from the bottom wall to an edge of the flow block.31. The discharge chamber of clause 29 wherein the dust collection screen comprises a plurality of layers of wire mesh.32. The discharge chamber of clause 31 wherein at least some of the layers of wire mesh are nonplanar.33. The discharge chamber of clause 32 wherein at least some of the layers of wire mesh are corrugated.34. The discharge chamber of clause 21 wherein the ramp surface is arranged to extend from the arcuate first surface towards the portion of the bottom wall and is slanted at a first angle towards the first side wall with respect to an extension of a radius of the circular outer circumference.35. The discharge chamber of clause 34 further comprising a dust collection screen arranged to cover at least a portion of an interior surface of at least one of the bottom wall, the second side wall, and the ramp surface.36. The discharge chamber of clause 35 wherein the dust collection screen comprises a plurality of layers of wire mesh.37. The discharge chamber of clause 36 wherein at least some of the layers of wire mesh are nonplanar.38. The discharge chamber of clause 37 wherein at least some of the layers of wire mesh are corrugated.

[0111] Other implementations are within the scope of the following claims.

Claims

CLAIMS1. A discharge chamber for a deep ultraviolet laser, the discharge chamber comprising: a chamber enclosure; a cross flow blower positioned in the chamber enclosure, the cross flow blower including an impeller comprising a plurality of impeller blades having outer edges arranged in relation to each other to define an outer circumference of the cross flow blower; and a flow block arranged between the impeller and an interior surface of the chamber enclosure at an intake portion of the cross flow blower, the flow block having a first surface facing and spaced away from a portion of the outer circumference, and a ramp surface arranged to extend from the first surface to a portion of the interior surface of the chamber enclosure.

2. The discharge chamber of claim 1 wherein the ramp surface is substantially straight and arranged to extend from the first surface to the portion of the interior surface of the chamber enclosure in a direction and at a position that is an extension of a radius of the outer circumference.

3. The discharge chamber of claim 1 wherein the flow block comprises an insert mechanically coupled to the interior surface of the chamber enclosure.

4. The discharge chamber of claim 1 wherein the flow block comprises an integral formation of the chamber enclosure.

5. The discharge chamber of claim 1 wherein the portion of the interior surface of the chamber enclosure is substantially straight and the ramp surface of the flow block forms an angle with the portion of the interior surface having a magnitude in a range of about 40 degrees to about 60 degrees.

6. The discharge chamber of claim 1 wherein the flow block is arranged to partially block inflow to a rear wall portion of the cross flow blower.

7. The discharge chamber of claim 1 wherein the flow block substantially fills a space between the impeller and an interior surface of a wall of the discharge chamber in a region including a rear wall portion of the cross flow blower.

8. The discharge chamber of claim 1 further comprising a second flow block arranged to form a vortex wall for the cross flow blower.

9. The discharge chamber of claim 1 further comprising a dust collection screen arranged to cover at least a portion of the second surface.

10. A discharge chamber assembly comprising: a discharge chamber; a cross flow blower configured to circulate gas through the discharge chamber, the cross flow blower and the discharge chamber being configured to create an intake region where gas enters the cross flow blower and an exhaust region where gas exits the blower; a first flow block positioned in a portion of the intake region to restrict the gas from entering the cross flow blower at a rear wall area of the cross flow blower; and a second flow block arranged to channel gas in the exhaust region of the cross flow blower and defining a vortex wall of the cross flow blower.

11. The discharge chamber assembly as in claim 10 wherein at least a portion of a surface of the discharge chamber adjacent the intake region is straight and wherein the first flow block has a ramp portion intersecting with the portion of the surface of the discharge chamber at an angle having a magnitude in a range of about 40 degrees to about 60 degrees.

12. A discharge chamber for a deep ultraviolet laser, the discharge chamber comprising: a chamber enclosure having a top wall adjacent to a discharge area, a bottom wall arranged opposed to the top wall, a first side wall, and a second side wall; a cross flow blower positioned in the chamber enclosure adjacent to the first side wall, the cross flow blower including an impeller comprising a plurality of impeller blades having outer edges arranged in relation to each other to define a circular outer circumference of the cross flow blower; and a flow block arranged at a corner of the first side wall and the bottom wall between the impeller and the bottom wall at an intake portion of the cross flow blower, the flow block having a first surface facing, spaced away from, and conforming to a portion of the outer circumference.

13. The discharge chamber of claim 12 wherein the flow block further comprises a ramp surface arranged to extend from the first surface towards a portion of the bottom wall.

14. The discharge chamber of claim 13 wherein the flow block substantially fills a volume bounded by the portion of the outer circumference, a portion of the bottom wall, a corner at which the first side wall and the bottom wall meet, portions of the first side wall and the bottom wall adjacent to the corner, and the ramp surface.

15. The discharge chamber of claim 14 further comprising a dust collection screen arranged to cover at least a portion of an interior surface of at least one of the bottom wall, the second side wall, and the ramp surface.

16. The discharge chamber of claim 15 wherein the dust collection screen comprises a plurality of layers of wire mesh.

17. The discharge chamber of claim 16 wherein at least some of the layers of wire mesh are nonplanar.

18. The discharge chamber of claim 17 wherein at least some of the layers of wire mesh are corrugated.

19. The discharge chamber of claim 12 wherein the flow block is spaced away from bottom wall and defines an upper and side surface of an open volume further defined by a corner at which the first side wall and the bottom wall meet and portions of the first side wall and the bottom wall adjacent to the corner.

20. The discharge chamber of claim 19 further comprising a dust collection screen arranged to cover at least a portion of an interior surface of at least one of the bottom wall and the second side wall.

Images