Gas discharge chamber blower fan with a textured surface

Abstract

A gas discharge apparatus of an ultraviolet (UV) light source includes: a gas chamber structure in which a gas discharge chamber is defined; and a blower fan within the gas discharge chamber. The blower fan includes: a fan mount that is fixed to the gas chamber structure; and a plurality of fan blades arranged in a cylindrical form about an axial direction and a plurality of fan blades arranged longitudinally along the axial direction such that a hollow cylindrical interior is defined. At least some of the fan blades have a surface with textures.

Description

GAS DISCHARGE CHAMBER BLOWER FAN WITH A TEXTURED SURFACECROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Application No. 63 / 595,166, filed November 1, 2023, titled GAS DISCHARGE CHAMBER BLOWER FAN WITH A TEXTURED SURFACE, which is incorporated herein in its entirety by reference.TECHNICAL FIELD

[0002] The disclosed subject matter relates to a blower fan within a gas discharge chamber.BACKGROUND

[0003] One kind of gas discharge light source used in photolithography is termed an excimer light source or laser. Typically, an excimer laser uses a combination of one or more noble gases, which can include argon, krypton, or xenon, and a reactive gas, which can include fluorine or chlorine. The excimer laser can create an excimer, a pseudo-molecule, under appropriate conditions of electrical simulation (energy supplied) and high pressure (of the gas mixture), the excimer only existing in an energized state. The excimer in an energized state gives rise to amplified light in the ultraviolet range. An excimer light source can use a single gas discharge chamber or a plurality of gas discharge chambers. When the excimer light source is performing, the excimer light source produces a deep ultraviolet (DUV) light beam. DUV light can include wavelengths from, for example, about 100 nanometers (nm) to about 400 nm.

[0004] The DUV light beam can be directed to a photolithography exposure apparatus or scanner, which is a machine that applies a desired pattern onto a target portion of a substrate (such as a silicon wafer). The DUV light beam interacts with a projection optical system, which projects the DUV light beam through a mask onto the photoresist of the wafer. In this way, one or more layers of chip design is patterned onto the photoresist and the wafer is subsequently etched and cleaned.SUMMARY

[0005] In some implementations, a gas discharge apparatus is configured for an ultraviolet (UV) light source. The gas discharge apparatus includes: a gas chamber structure in which a gas discharge chamber is defined; and a blower fan within the gas discharge chamber. The blower fan includes: a fan mount that is fixed to the gas chamber structure; and a plurality of fan blades arranged in a cylindrical form about an axial direction and a plurality of fan blades arranged longitudinally along the axial direction such that a hollow cylindrical interior is defined. At least some of the fan blades have a surface with textures.

[0006] Implementations can include one or more of the following features. For example, the textures on the surface of the fan blades can include depressions in the surface of the fan blade. The textures on the surface of the fan blades can include symmetrically-shaped depressions in the surface of the fan blade. Each fan blade can have a thickness of between 0.5 millimeters (mm) to 1.5 mm. The textures of the surface of the fan blades can include depressions, and each depression can have a depth that is 10-50% of the thickness of the fan blade that includes the depression. Each fan blade can have a thickness of between 0.6 mm to 1.0 mm, and the textures of the surface of the fan blades can include depressions and each depression can have a depth that is 15-25% of the thickness of the fan blade that includes the depression. The textures of the surface of the fan blade can include one or more of depressions and protrusions arranged to cover 10-80% of the total surface of the fan blade. Each fan blade surface having textures can be a curved plane. The blower fan can include hub members arranged along the axial direction such that each fan blade extends from one hub member to another hub member. A surface of at least one hub member can have textures. Each hub member and each fan blade can have a thickness between 0.5 mm and 1.5 mm. Each hub member and each fan blade can have a thickness between 0.6 mm and 1.0 mm. Each fan blade can include a connected portion; each fan blade can be connected to a hub member at its connected portion; each fan blade can include a smooth surfaced face; and the surface with textures can increase a recirculation flow at a region remote from the connected portion. The textures of the surface can include one or more of dimples, grooves, and protrusions. At least half of, at least 75% of, or at least 90% of the fan blades can include textures at the surface. The textures of the surface can be configured to decrease an amount of drag on the fan blades as the blower fan is rotating about the axial direction. The fan blades can include a metal or a ceramic. The fan blades can include a nickel coated aluminum. The fan blades can be rotated about the axial direction under control of a motor. The textures of the surface can be arranged in a pattern. The textures of the surface can be randomly arranged on the surface. The textures of the surface are arranged according to a direction of flow of a gas mixture across the surface.

[0007] The gas discharge apparatus can also include: a gas; an anode; and a cathode. The blower fan can be configured to blow the gas between the anode and the cathode. The textures on the at least some of the fan blades having a surface with textures can decrease the amount of drag on the fan blades.

[0008] In other general aspects, a blower fan is configured for a gas discharge chamber of an ultraviolet (UV) light source. The blower fan includes: a fan mount configured to be mounted to a chamber structure of the gas discharge chamber, and a plurality of fan blades arranged in a cylindrical pattern about an axial direction and a plurality of fan blades arranged longitudinally along the axial direction between annular hub members such that a hollow cylindrical interior is defined. At least some of the surfaces of the fan blades and the annular hub members have textures.

[0009] Implementations can include one or more of the following features. For example, the textures on the surface can include depressions in the surface or protrusions on the surface. Each depression on a fan blade can have a depth that is 10-50% of a thickness of the fan blade and each protrusion on a fan blade can have a height that is 10-50% of the thickness of the fan blade. Each fan blade can be a curved plane. Each fan blade can extend from an annular hub member. The annular hub members and the fan blades can each have a thickness between 0.5 mm and 1.5 mm. Each fan blade can include a connected portion; each fan blade can be connected to a hub member at its connected portion; each fan blade can include a smooth surfaced face; and the surface of the fan blade with textures can increase a recirculation flow. At least half of, at least 75% of, or at least 90% of the fan blades and the annular hub members can include textures at the surface. The fan blades and the hub members can include or be made of a metal or a ceramic. The fan blades can be rotated about the axial direction under control of a motor.

[0010] In other general aspects, an ultraviolet (UV) light source includes: a gas discharge chamber; a cylindrical blower fan located within the gas discharge chamber, and electrodes located in the gas discharge chamber. The cylindrical blower fan includes: a plurality of fan blades arranged in a cylindrical form between annular hub members, at least some of the fan blades and the annular hub members having a surface with textures. The cylindrical blower fan is configured to flow a gas mixture between the electrodes. The textures on the at least some of the surfaces of the fan blades and the annular hub members decrease the amount of drag on the cylindrical blower fan.

[0011] Implementations can include one or more of the following features. For example, each fan blade can be fixed to an annular hub member. Each annular hub member and each fan blade can have a thickness between 0.5 mm and 1.5 mm. The textures of the surface with textures on a fan blade or on an annular hub member can have a depth of between 0.1 and 0.4 mm into the thickness of the fan blade or the annular hub member. The UV light source can also include a motor. The fan blades can be rotated about the axial direction under control of the motor. The textures of the surface can be arranged in a pattern.DESCRIPTION OF DRAWINGS

[0012] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable a person skilled in the relevant art(s) to make and use implementations described herein.

[0013] FIG. 1A is a perspective cross-sectional view of a gas discharge apparatus including a gas discharge structure defining a chamber in which a blower fan is mounted relative to electrodes;

[0014] FIG. IB is a cross-sectional view of the gas discharge apparatus of FIG. 1A taken along plane IB- IB (which is the XY plane);

[0015] FIG. 1C is a cross-sectional view of the gas discharge apparatus of FIG. 1A taken along plane 1C-1C (which is the YZ plane);

[0016] FIG. 2A is a perspective view of an implementation of the blower fan of FIGS. 1 A-1C;

[0017] FIG. 2B is a side cutaway view of the blower fan of FIG. 2A;

[0018] FIG. 3A is a plan view of an implementation of a fan blade of the blower fan of FIGS. 1 A-2B, in which the fan blade includes textures on a convex surface;

[0019] FIG. 3B is a cross-sectional view of the fan blade of FIG. 3 A taken along line 3B-3B;

[0020] FIG. 3C is a cross-sectional view of the blower fan including the fan blade of FIGS. 3A and 3B mounted to an annular hub member;

[0021] FIGS. 4A-4D are plan views of different implementations of textures on a fan blade of a blower fan of FIGS. 1A-2B;

[0022] FIG. 5 is a schematic illustration of the gas discharge apparatus of FIG. 1 A in an implementation of a light source for supplying a light beam to an output apparatus;

[0023] FIG. 6 is a schematic illustration of the gas discharge apparatus of FIG. 1 A in an implementation of a dual-stage light source for supplying a light beam to an output apparatus that is a photolithography exposure apparatus;

[0024] FIG. 7 A is a plan view of an implementation of a fan blade of the blower fan of FIGS. 1 A-2B, in which the fan blade includes textures on a concave surface;

[0025] FIG. 7B is a cross-sectional view of the fan blade of FIG. 7A taken along line 7B-7B;

[0026] FIG. 7C is a cross-sectional view of the blower fan including the fan blade of FIGS. 7A and 7B mounted to an annular hub member; and

[0027] FIG. 8 is a cross-sectional view of the blower fan including fan blade of FIGS. 3A, 3B, 7A, and 7B mounted to an annular hub member and including textures on the annular hub member.

[0028] The features of the present disclosure will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and / or structurally similar elements. Additionally, generally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears. Unless otherwise indicated, the drawings provided throughout the disclosure should not be interpreted as to-scale drawings.DESCRIPTION

[0029] Referring to FIGS. 1A-1C, a gas discharge apparatus 100 includes a gas discharge chamber 104 that is defined by a gas discharge structure 120. The gas discharge apparatus 100 can be used in a deep ultraviolet (DUV) light source (such as the DUV light source 505 shown in FIG. 5). The gas discharge chamber 104 is configured to hold a gas mixture 107 and to house electrodes 130, 140, asillustrated in FIGS. IB and 1C. The gas mixture 107 includes a gain medium. The first electrode 130 can be a cathode and the second electrode 140 can be an anode. The electrodes 130, 140 are configured to supply energy to the gain medium of the gas mixture 107 to thereby produce a light beam (such as light beam 502 in FIG. 5). The gain medium of the gas mixture 107 is configured to emit DUV light in response to a voltage signal being applied to the anode 130 and cathode 140. For a DUV light source, the gain medium of the gas mixture 107 can include, for example, argon fluoride (ArF), krypton fluoride (KrF), or xenon chloride (XeCl).

[0030] Specifically, the cathode 130 and the anode 140 have a potential difference that forms an electric field in the gas mixture 107. The electric field provides energy to the gain medium within the gas mixture 107, such energy sufficient to cause a population inversion and to enable generation of a pulse of light via stimulated emission. Repeated creation of such a potential difference forms the train of optical pulses that eventually make up the light beam 502 (FIG. 5 ). A “discharge event” is the application of voltage to the cathode 130 and the anode 140 that forms a potential difference sufficient to cause an electrical discharge in the gain medium of the gas mixture 107 and the emission of a pulse of light in the light beam 502. As shown in FIG. 5, an output light beam 503 that is formed from the light beam 502 is directed to an output device 501, which can be a photolithography exposure apparatus.

[0031] When an optical pulse is generated from the gas mixture 107 between or near the cathode 130 and the anode 140, there is a period of time during which the molecules within the gain medium of the gas mixture 107 recover. This recovery time is longer than the desired time between pulses of the cathode 130 and the anode 140. Moreover, if another pulse of energy is supplied to the recovering gas mixture 107, which remains nearest the cathode 130 and the anode 140, then output quality of the resultant optical pulse of the light beam 502 (FIG. 5) will be reduced.

[0032] To fix this issue, the gas discharge chamber 104 includes a blower fan 108 including a plurality of fan blades 150 arranged longitudinally along an axial direction 108d and radially around the axial direction 108d. To keep the drawings less cluttered, only three of the fan blades 150 are labeled in each of FIGS. 1 A-1C. The axial direction 108d is aligned with the X axis in the X,Y,Z coordinate system shown in FIGS. 1A-1C. In various implementations, the blower fan 108 includes a rotating structure defined by the plurality of fan blades 150 and other features that enable it to remain intact and not deform during rotation. For example, the fan blades 150 can be arranged relative to or extending from annularly-shaped and axially-displaced hub members 160. An example of a prior blower fan is described in U.S. Patent No. 6,765,946, issued on July 20, 2004 and naming Partlo et al., as inventors, which is incorporated herein by reference in its entirety.

[0033] The blower fan 108 is configured to regularly displace the portion of the recovering gas mixture 107 away from the discharge region, that is, the region between the cathode 130 and the anode 140, within the gas discharge chamber 104 to enable fresh gas mixture 107 to interact with thecathode 130 and the anode 140 before a next pulse of the cathode 130 and the anode 140 is produced. If the speed of the blower fan 108 is too low, then arcing, dropouts, and inefficiency can occur in the gas discharge chamber 104, and the gas discharge chamber 104 can fail when the blower fan 108 is unable to sufficiently clear the portion of the recovering gas mixture 107. Another consideration is that the rotation or motion of the blower fan 108 can cause vibrations within the gas discharge chamber 104 that can impact one or more spectral properties of the light beam as well as the dose performance of the light beam at a lithography exposure apparatus.

[0034] FIG. 1C illustrates the rotation of the blower fan 108. Specifically, the blower fan 108 rotates the fan blades 150 in a clockwise direction (in the page) about the axial direction 108d as shown by the arrow A to cause the gas mixture 107 to rotate within the gas discharge chamber 104. This directs a gas flow 135 along the path B. Gas flow 135 is directed along the path B between the first electrode 130 and the second electrode 140. Improving the efficiency of the blower fan 108 enables more gas flow 135 within the gas discharge chamber 104.

[0035] During operation of the gas discharge apparatus 100, an operating speed of the blower fan 108 (that is the speed or rate at which the blower fan 108 rotates about a rotational axis, the axial direction 108d, of the blower fan 108) can be maintained constant at a pre-configured speed. Specifically, the operating speed of the blower fan 108 can be maintained at a maximum blower speed such that the operating speed of the blower fan 108 does not change over time and as the gas discharge apparatus 100 operates.

[0036] In general, the operating speed of the blower fan 108 is limited by the size of the blower fan 108 and a motor 195 (FIG. IB) that controls the blower fan 108. It is not practical to increase the size of the blower fan 108 because the size of the blower fan 108 is limited by the space allotted for the blower fan 108 within the gas discharge chamber 104. Moreover, it is also not practical to upgrade the motor 195.

[0037] In order to increase the operating speed of the blower fan 108, at least some surfaces of the blower fan 108 have textures. For example, some of, most of, or all of the fan blades 150 of the blower fan 108 have a surface with textures 155. To improve clarity, only a few textures 155 are labeled in FIGS. 1A-1C. As another example, the surfaces of some of, most of, or all of the hub members 160 can also include textures 165. The textures 155 on the fan blades 150 (and, optionally, the textures 165 on the hub members 160) can improve the flow needed to clear contaminants in discharge region of the gas discharge chamber 104 to thereby increase the pumping efficiency of the blower fan 108 during operation of the light source in which the gas discharge apparatus 100 is used. The textures 155 (and optionally, the textures 165) can reduce eddies and turbulent regions near the fan blades 150, and the hub members 160, and this can lead to improvement in pumping efficiency of the blower fan 108. Additionally, the textures 155 (and optionally, the textures 165) can defuse acoustic effects in the gas discharge chamber 104 caused by the blower fan 108 during operation ofthe gas discharge apparatus 100. In general, the textures 155 (and optionally, the textures 165) improve the efficiency of operation of the blower fan 108.

[0038] The increased efficiency of the blower fan 108 (due to the textures 155 on the fan blades 150 and / or the textures 165 on the hub members 160) increases the movement of the gas mixture 107 from the rotation of the blower fan 108.

[0039] As illustrated in FIGS. 1A-1C, the fan blades 150 are arranged longitudinally along the axial direction 108d and radially around the axial direction 108d. More specifically, the fan blades 150 are arranged in a cylindrical form about the axial direction 108d. A hollow cylindrical interior 108i (FIG. 1C) is defined within the arrangement of the fan blades 150. The blower fan 108 also includes the hub members 160 that provide structure. The hub members 160 are annular discs arranged with their planes in the YZ direction and spaced apart longitudinally along the axial direction 108d. Each fan blade 150 extends from one hub member 160 to an adjacent hub member 160. The hub members 160 provide a structure to fix or hold the fan blades 150.

[0040] In general, the blower fan 108 can be constructed using any combination of additive and subtractive manufacturing processes. For example, in some implementations, the fan blades 150 and the hub members 160 are formed from the same solid material by a subtractive manufacturing process. In other implementations, the fan blades 150 and the hub members 160 are formed using an additive manufacturing process, such as, for example, three-dimensional metal printing such as direct metal laser sintering or DMLS, directed energy deposition or DED, and sintering. Each fan blade 150 and each hub member 160 is made of a structural material that is compatible with and not reactive to the gas mixture 107. As noted above, the gas mixture 107 can include a gain medium such as argon fluoride (ArF), krypton fluoride (KrF), or xenon chloride (XeCl) and thus the material of each fan blade 150 and each hub member 160 is compatible with and not reactive to argon fluoride (ArF), krypton fluoride (KrF), or xenon chloride (XeCl). In some implementations, the fan blades 150 and the hub members 160 are made of a metal or a ceramic. For example, the fan blades 150 and the hub members 160 can be made of a nickel coated aluminum, or any structural material compatible with and not reactive to the gas mixture 107.

[0041] FIG. IB illustrates the blower fan 108 secured within the gas discharge chamber 104. To this end, the blower fan 108 includes at least one hub end flange 180 configured to provide a structure for mounting the blower fan 108 to the gas discharge structure 120. As illustrated, the blower fan 108 can attach to the gas chamber structure 120 via an axial arm 185 that attaches to a fan mount 190 on the gas chamber structure 120. The axial arm 185 can extend out of the gas chamber structure 120 to the motor 195 that is configured to rotate the blower fan 108. In some implementations, the blower fan 108 is secured at both ends to different portions of the gas discharge structures 120 using respective hub end flanges 180, respective axial arms 185, and respective fan mounts 190 (as shown in FIG. IB). The fan mounts 190 are configured to be mounted to the gas chamber structure 120 of the gasdischarge apparatus 100 such that the fan mounts 190 are fixed to the gas chamber structure 120. For example, each fan mount 190 can be fixedly attached a wall of the gas chamber structure 120.

[0042] Using the implementation of the blower fan 108 in FIG. IB, the blower fan 108 rotates around the axial direction 108d under control of the motor 195 while the fan mounts 190 hold the axial arms 185 securely within the gas discharge chamber 104.

[0043] As shown in FIGS. 1A-1C, each fan blade 150 is shaped like a curved plane or airfoil, with the plane being curved around one, or more, local axes, each local axis being parallel with the axial direction 108d. The textures 155 can be formed on the convex surface of the fan blade 150. Moreover, the textures 155 can correspond to depressions or indentations in the convex surface of the fan blade 150.

[0044] FIGS. 2 A and 2B illustrate an implementation 208 of the blower fan 108 separated from the gas discharge chamber 104. The local coordinate system of the blower fan 208 is given by XF,YF,ZF, where the axial direction 208d is aligned with the XF axis and when installed in the gas chamber structure 120, the XF,YF,ZF coordinate system aligns with the X,Y,Z coordinate system of the gas discharge apparatus 100.

[0045] As illustrated in FIG. 2A, the blower fan 208 has hub end flanges 280 on each end, fan blades 250 extending between the flanges 280 longitudinally and radially about the axial direction 208d, and hub members 260 spaced apart along the longitudinal direction of the blower fan 208. At least some of the fan blades 250 have a surface with textures 255. Again, only some of the fan blades 250 are shown as having surfaces with textures 255. More or fewer surfaces of the fan blades 250 can have textures 255 and there can be more or fewer textures 255 on each fan blade 250 than shown. The region between adjacent hub members 260 in which the fan blades 250 extend can be referred to as segments 270.

[0046] The blower fan 208 can be formed from a monolithic unit cylinder with hub end flanges 280 fixedly attached thereto. The fan blades 250 and the hub members 260 can be machined from (using subtractive manufacturing) the monolithic unit cylinder, such as a tube. The fan blades 250 can be machined such that stiffening areas are formed in the corners of the fan blades 250 connecting the ends of the fan blades 250 to the annular surfaces of the hub members 260, to provide a structurally rigid blower fan 208. The hub end flanges 280 can be secured to the blower fan 208 (such as the end hub members 260) by bolts (not shown) and can provide additional stiffness against bending moments caused during blower fan 208 operation.

[0047] The blower fan 208 is sized to fit within the gas discharge chamber 104 of FIG. 1 A. The blower fan 208 can have a diameter (in the YF,ZF plane) of about 5 inches and an axial length (in the XF axis) of 20-30 inches.

[0048] The methods of manufacturing and machining fan blades 250 are further discussed in Partlo et al., U.S. Patent No. 6,765,946, which was incorporated by reference as discussed above.

[0049] FIG. 2B shows a side view (and a simplified outer area) of a segment of the blower fan 208 such that the positioning of the fan blades 250, the hub members 260, the segments 270, and the hub end flanges 280 are more clearly shown in relative positioning. The fan blades 250 are located between the hub members 260, and the hub end flange 280 is located adjacent to the hub member 260.

[0050] When machining from a monolithic cylinder, the fan blades 250 and the hub members 260 can have substantially the same thickness since they are manufactured together from the same monolithic cylinder. The thickness of a fan blade 250 is taking along a local radial direction (such as in the YB, ZB plane as shown in FIG. 3B and the thickness of the hub member 260 can be taken along the axial direction XF (FIG. 2A).

[0051] The fan blades 250 and the hub members 260 can be made of a metal or ceramic, such as a nickel coated aluminum.

[0052] As also shown in FIG. 2B, surfaces of one or more of the fan blades 250 can be provided with textures 255. Some surfaces can have different numbers or geometries of textures 255 from other surfaces of the fan blades 250. The textures 255 of the surface of a fan blade 250 can cover 10-80% of the total surface of the fan blade 250. As illustrated, the surfaces of the fan blades 250-1, 250-2 include a higher density of the textures 255-1, 255-2, respectively, than other fan blades. For example, the textures 255-1 can cover 80% of the total surface of the fan blade 250-1 and the textures 255-2 can cover 75% of the total surface of the fan blade 250-2. The fan blade 250-3 can have a lower density of textures 255-3, for example, the textures 255-3 can cover 40% of the total surface of the fan blade 255-3. One or more fan blades 250 can also be provided with no textures. For example, the surface of the fan blade 250-4 lacks any textures.

[0053] Some of the textures 255 can be arranged in a repeatable pattern, while other textures can be randomly distributed across the surface of the fan blade 250.

[0054] By providing fan blades 250 with textures 255, the amount of drag on the fan blades 250 can be reduced. By providing particular patterns of higher or lower density of textures 255, the amount of drag on the fan blades 250, as well as any fan buffeting or cavitation, can be reduced or altered.

[0055] FIGS. 3 A and 3B illustrate an example of a single fan blade 350i from a the blower fan 208 of FIGS. 2A and 2B. As shown in FIGS. 3A and 3B, a convex surface 353 includes textures 355. The textures 355, as mentioned above, can be densely or sparsely provided on the surface 353. The surface 353 extends along a local XB,ZB plane but it is a curved plane, that is, it is curved or bulges along the local YB axis, as shown more clearly in FIG. 3B. FIG. 3C shows the fan blade 350i arranged around a single hub member 360 along with other fan blades 350 such that the YB,ZB plane of the fan blade 350i is overlapping with or parallel with the YF,ZF plane of the blower fan 208 in which it is fixed.

[0056] In this implementation, the textures 355 are dimples or depressions within the surface 353 of the fan blade 350i. For example, the textures 355 can be depressions having a depth d along the local radial direction (in the YB,ZB plane). The local radial direction is defined by the curvature of thesurface 353. The depth d can be 10-50% or 15-25% of the total thickness t of the fan blade 350i, where the total thickness t is also taken along the local radial direction in the YB,ZB plane as shown in FIG. 3B. In some implementation, each of the textures 355 have the same depth d. In other implementations, each of the textures 355 has a depth d that is different when compared to one or more other textures 355 of the fan blade 350i. For example, on a fan blade 350i with a thickness t of 0.5 mm to 1.5 mm, the textures 355 can have a depth d of 0.1 mm to 0.4 mm into the surface 353 of the fan blade 350i. The depth d of the textures 355 is not necessarily limited by the thickness t of the fan blade 350i. The depth d of the textures 355 can be based on one or more of the density of the gas mixture 107, the viscosity of the gas mixture 107, and the surface speed of the gas mixture 107 near the fan blade 350i.

[0057] The textures 355 can be symmetrically-shaped depressions in the surface 353 of the fan blade 350i. For example, the depression can have line symmetry such as shown. An oval has line symmetry. The depression can have rotational symmetry. An example of a depression that has rotational symmetry is a polygon or a circle. As illustrated in FIG. 3C, the textures 355 can be included on at least half, at least 75%, or at least 90% of the fan blades 350. As shown in FIG. 3 A, the textures can include depressions 355 arranged to cover 10-80% of the total surface 353 of the fan blade 350i. The fan blade 350i can include a smooth surface 356 that lacks any textures 355. In this example, the smooth surface 356 is opposite to the surface 353 having the textures 355. In some implementations, the blower fan 208 can include at least one or several fan blades that lack a surface having textures. An example of such a fan blade 350k is shown in FIG. 3C.

[0058] The fan blade 350i, as illustrated in FIG. 3A, is a curved plane and can define or include a connected portion or surface 352. The connected portion 352 of the fan blade 350i can be connected to the hub member 260, as shown in FIGS. 2A and 2B.

[0059] The angle of the curved plane can be adjusted along with the quantity, size, and location of the textures 355 on the fan blade 350i to provide efficiency and reduce buffeting or cavitation of the gas mixture 107 in the blower fan 108 and the gas discharge chamber 104 of FIG. 1A, for example.

[0060] The textures 355 can be any shape and can be configured to decrease the drag on the fan blade 350i. The textures 355 can be depressions or dimples in the surface 353 of the fan blade 350i. For example, the textures 355 can be shaped as semi-circular dimples (such as shown in FIG. 3A) that decrease the amount of drag on the fan blade 350i while the blower fan 108, for example from FIG. IB, is rotating around the axial direction 108d.

[0061] As mentioned above, the textures 355 can be arranged in any pattern along the surface 353 as well. For example, as illustrated in FIGS. 3 A and 4A, the textures 355, 455 A can be placed in a symmetrical, regularly spaced pattern on the surface 353, 453A of the fan blade 350i, 450A. As shown in FIG. 4B, the textures 455B can be placed in an asymmetrically, regularly spaced pattern on the surface 453B of the fan blade 450B. As shown in FIG. 4C, the textures 455C can be placed in asymmetrical, irregularly spaced pattern on the surface 453C of the fan blade 450C. And, as shown in FIG. 4D, the textures 455D can be placed in an asymmetrical, irregularly spaced pattern on the surface 453D of the fan blade 450D. Alternatively, the textures 355 can be randomly arranged on the fan blade 350. Each fan blade 450A, 450B, 450C, 450D is a curved plane and can define or include a respective connected portion or surface 452A, 452B, 452C, 452D. The connected portion 452A, 452B, 452C, 452D of the fan blade 450A, 450B, 450C, 450D can be connected to the hub member 260, as shown in FIGS. 2 A and 2B.

[0062] By providing textures 355 on the fan blades 150 of the blower fans 108, increased efficiency of the blower fan 108 increases the movement of the gas mixture 107 from the rotation of the blower fan 108 and thus allows improved formation of output light beam 503 (FIG. 5) to be provided to the output apparatus 501 (FIG. 5).

[0063] Referring to FIG. 5, in an implementation, a DUV light source 505 is illustrated with a blower fan 508 with textures 555 on its fan blades 550. The textures 555 on the fan blades 550 assist in moving a gas mixture 507 between electrodes 530, 540, as discussed above. The electrodes 530, 540 have a discharge event in the gain medium of the gas mixture 507 to emit a pulse of DUV light in the light beam 502. The output light beam 503 (formed from the light beam 502) is provided from the DUV light source 505 to the output apparatus 501, which can be a photolithography exposure apparatus. The DUV light source 505 can include other elements 510 for adjusting, modifying, measuring, and directing the light beam 502 can be a part of the DUV light source 505.

[0064] Referring to FIG. 6, an implementation 605 of the light source 505 includes two gas discharge apparatuses 600A, 600B that are designed like the gas discharge apparatus 100. The light source 605 produces the pulsed output light beam 603 directed to a photo lithography exposure apparatus 601. The pulsed output light beam 603 has a wavelength in the ultraviolet range (for example, in the deep ultraviolet range) for use by the photolithography exposure apparatus 601 for patterning a semiconductor substrate or wafer 611. In the example of FIG. 6, the gas discharge apparatus 600A is a part of a master oscillator configured to produce a seed light beam 612 and the gas discharge apparatus 600B is a part of a power amplifier configured to produce the output light beam 603 from the seed light beam 612. Each of the gas discharge apparatuses 600A, 600B includes a respective gas discharge chamber 604A, 604B, which each include a respective blower fan 608 A, 608B. Each of the blower fans 608 A, 608B is designed like the blower fan 108.

[0065] Each gas discharge chamber 604A, 604B is configured to hold the respective gas mixture 607A, 607B. The gas mixture 607A, 607B used in the respective discharge chamber 604A, 604B can be a combination of suitable gases for producing the respective light beam 612, 603 around the required wavelengths, bandwidth, and energy. For example, the gas mixture 607 A, 607B can include argon fluoride (ArF), which emits light at a wavelength of about 193 nm. Each gas discharge chamber 604A, 604B is defined by respective chamber walls configured to hold the respective blower fans608 A, 608B. Each gas discharge chamber 604A, 604B houses the respective electrodes 630A, 640A, 630B, 640B forming respective energy sources configured to supply energy to the gas mixture 607A, 607B. As discussed above, each energy source can include a respective pair of electrodes 630A / 640A, 630B / 640B that form a potential difference and, in operation, excite the gain medium of the gas mixture 607A, 607B.

[0066] The gas discharge apparatus 600A includes, among other features, optical components 675A, 676 A configured to form an oscillator cavity within the gas discharge chamber 604A. The gas discharge apparatus 600B includes, among other features, optical components 675B, 676B configured to form a power amplifier within the gas discharge chamber 604B.

[0067] The light source 605 can also include a control system configured to control the respective operating speeds of the two blower fans 608A, 608B. In some implementations, the control of the operating speed of the blower fan 608A can be independent of the control of the operating speed of the blower fan 608B.

[0068] Referring to FIGS. 7A-7C, in some implementations, textures 755 can be formed on a concave surface 754 of a fan blade 750i. For example, some of the fan blades 150 can have textures on the convex surface (such as shown in FIGS. 3A-3C) while other of the fan blades 150 can have textures on the concave surface (such as shown in FIGS. 7A-7C). The textures 755, as mentioned above, can be densely or sparsely provided on the surface 754. The surface 754 extends along a local XB,ZB plane but it is a curved plane, that is, it is curved or bulges along the local YB axis, as shown more clearly in FIG. 7B. FIG. 7C shows the fan blade 750i arranged around a single hub member 760 along with other fan blades 750 such that the YB,ZB plane of the fan blade 750i is overlapping with or parallel with the YF,ZF plane of the blower fan 208 (FIGS. 2A and 2B) in which it is fixed.

[0069] In this implementation, the textures 755 are dimples or depressions within the surface 754 of the fan blade 750i. For example, the textures 755 can be depressions having a depth d along the local radial direction (in the YB,ZB plane). The local radial direction is defined by the curvature of the surface 754. The depth d can be 10-50% or 15-25% of the total thickness t of the fan blade 750i, where the total thickness t is also taken along the local radial direction in the YB,ZB plane as shown in FIG. 7B. In some implementation, each of the textures 755 have the same depth d. In other implementations, each of the textures 755 has a depth d that is different when compared to one or more other textures 755 of the fan blade 750i. For example, on a fan blade 750i with a thickness t of 0.5 mm to 1.5 mm, the textures 755 can have a depth d of 0.1 mm to 0.4 mm into the surface 754 of the fan blade 750i. The depth d of the textures 355 is not necessarily limited by the thickness t of the fan blade 350i. As discussed above, the depth d of the textures 755 can be based on one or more of the density of the gas mixture 107, the viscosity of the gas mixture 107, and the surface speed of the gas mixture 107 near the fan blade 750i.

[0070] The textures 755 can be symmetrically-shaped depressions in the surface 754 of the fan blade 750i. For example, the depression can have line symmetry such as shown. An oval has line symmetry. The depression can have rotational symmetry. An example of a depression that has rotational symmetry is a polygon or a circle. As illustrated in FIG. 7C, the textures 755 can be included on at least half, at least 75%, or at least 90% of the fan blades 350. As shown in FIG. 7A, the textures 755 can include depressions arranged to cover 10-80% of the total surface 754 of the fan blade 750i. The fan blade 750i can include a smooth surface 756 that lacks any textures 755. In this example, the smooth surface 756 is opposite to the surface 754 having the textures 755. In some implementations, the blower fan 208 can include at least one or several fan blades that lack a surface having textures. An example of such a fan blade 750k is shown in FIG. 7C.

[0071] The fan blade 750i, as illustrated in FIG. 7A, is a curved plane and can define or include a connected portion or surface 752. The connected portion 752 of the fan blade 750i can be connected to the hub member 760.

[0072] The angle of the curved plane can be adjusted along with the quantity, size, and location of the textures 755 on the fan blade 750i to provide efficiency and reduce buffeting or cavitation of the gas mixture 107 in the blower fan 108 and the gas discharge chamber 104 of FIG. 1A, for example.

[0073] The textures 755 can be any shape and can be configured to decrease the drag on the fan blade 750i. The textures 755 can be depressions or dimples in the surface 754 of the fan blade 750i. For example, the textures 755 can be shaped as semi-circular dimples (such as shown in FIG. 7A) that decrease the amount of drag on the fan blade 750i while the blower fan 108, for example from FIG. IB, is rotating around the axial direction 108d.

[0074] As mentioned above, the textures 755 can be arranged in any pattern along the surface 754 as well, as discussed above with reference to FIGS. 4A-4D.

[0075] Referring to FIG. 8, in some implementations, textures 865 are formed on surfaces of one or more of the hub members 860. Fan blades 850k, 850, 850i extend from the hub member 860. In this example, the surfaces of the fan blades 850i and 850 include their own textures 855 while the surface of the fan blade 850k lacks any texture.

[0076] In other implementations, such as shown in FIG. 8, the textures 155 or 165 are protrusions that extend out from the surface of the fan blade 150 or the annular hub member 160. For example, the surface of fan blade 850j includes protrusions 866j as textures.

[0077] Changes and modifications of the implementations described herein can be made without departing from the descriptions herein. The implementations described herein are merely illustrative and are not intended to encompass all changes and modifications.

[0078] The implementations can be further described using the following clauses:1. A gas discharge apparatus of an ultraviolet (UV) light source, the gas discharge apparatus comprising:a gas chamber structure in which a gas discharge chamber is defined; and a blower fan within the gas discharge chamber, the blower fan comprising: a fan mount that is fixed to the gas chamber structure; and a plurality of fan blades arranged in a cylindrical form about an axial direction and a plurality of fan blades arranged longitudinally along the axial direction such that a hollow cylindrical interior is defined, wherein at least some of the fan blades have a surface with textures.2. The gas discharge apparatus of clause 1, wherein the textures on the surface of the fan blades comprise depressions in the surface of the fan blade.3. The gas discharge apparatus of clause 1, wherein the textures on the surface of the fan blades comprise symmetrically-shaped depressions in the surface of the fan blade.4. The gas discharge apparatus of clause 1 , wherein each fan blade has a thickness of between 0.5 millimeters (mm) to 1.5 mm.5. The gas discharge apparatus of clause 4, wherein the textures of the surface of the fan blades comprise depressions, and wherein each depression has a depth that is 10-50% of the thickness of the fan blade that includes the depression.6. The gas discharge apparatus of clause 4, wherein each fan blade has a thickness of between 0.6 mm to 1.0 mm, and wherein the textures of the surface of the fan blades comprise depressions and each depression has a depth that is 15-25% of the thickness of the fan blade that includes the depression.7. The gas discharge apparatus of clause 1, wherein the textures of the surface of the fan blade comprise one or more of depressions and protrusions arranged to cover 10-80% of the total surface of the fan blade.8. The gas discharge apparatus of clause 1, wherein each fan blade surface having textures is a curved plane.9. The gas discharge apparatus of clause 1, wherein the blower fan further comprises hub members arranged along the axial direction such that each fan blade extends from one hub member to another hub member.10. The gas discharge apparatus of clause 9, wherein a surface of at least one hub member has textures.11. The gas discharge apparatus of clause 9, wherein each hub member and each fan blade has a thickness between 0.5 mm and 1.5 mm.12. The gas discharge apparatus of clause 9, wherein each hub member and each fan blade has a thickness between 0.6 mm and 1.0 mm.13. The gas discharge apparatus of clause 9, wherein: each fan blade comprises a connected portion; each fan blade is connected to a hub member at its connected portion; each fan blade comprises a smooth surfaced face; andthe surface with textures increases a recirculation flow at a region remote from the connected portion.14. The gas discharge apparatus of clause 1, wherein the textures of the surface comprise one or more of dimples, grooves, and protrusions.15. The gas discharge apparatus of clause 1, wherein at least half of, at least 75% of, or at least 90% of the fan blades include textures at the surface.16. The gas discharge apparatus of clause 1, wherein the textures of the surface are configured to decrease an amount of drag on the fan blades as the blower fan is rotating about the axial direction.17. The gas discharge apparatus of clause 1, wherein the fan blades comprise a metal or a ceramic.18. The gas discharge apparatus of clause 17, wherein the fan blades comprise a nickel coated aluminum.19. The gas discharge apparatus of clause 1, wherein the fan blades are rotated about the axial direction under control of a motor.20. The gas discharge apparatus of clause 1 , wherein the textures of the surface are arranged in a pattern.21. The gas discharge apparatus of clause 1, wherein the textures of the surface are randomly arranged on the surface.22. The gas discharge apparatus of clause 1, wherein the textures of the surface are arranged according to a direction of flow of a gas mixture across the surface.23. The gas discharge apparatus of clause 1, further comprising: a gas; an anode; and a cathode, wherein the blower fan is configured to blow the gas between the anode and the cathode, and wherein the textures on the at least some of the fan blades having a surface with textures decrease the amount of drag on the fan blades.24. A blower fan for a gas discharge chamber of an ultraviolet (UV) light source, the blower fan comprising: a fan mount configured to be mounted to a chamber structure of the gas discharge chamber, and a plurality of fan blades arranged in a cylindrical pattern about an axial direction and a plurality of fan blades arranged longitudinally along the axial direction between annular hub members such that a hollow cylindrical interior is defined, wherein at least some of the surfaces of the fan blades and the annular hub members have textures.25. The blower fan of clause 24, wherein the textures on the surface comprise depressions in the surface or protrusions on the surface.26. The blower fan of clause 25, wherein each depression on a fan blade has a depth that is 10- 50% of a thickness of the fan blade and each protrusion on a fan blade has a height that is 10-50% of the thickness of the fan blade.27. The blower fan of clause 24, wherein each fan blade is a curved plane.28. The blower fan of clause 24, wherein each fan blade extends from an annular hub member, the annular hub members and the fan blades each have a thickness between 0.5 mm and 1.5 mm.29. The blower fan of clause 24, wherein: each fan blade comprises a connected portion; each fan blade is connected to a hub member at its connected portion; each fan blade comprises a smooth surfaced face; and the surface of the fan blade with textures increases a recirculation flow.30. The blower fan of clause 24, wherein at least half of, at least 75% of, or at least 90% of the fan blades and the annular hub members include textures at the surface.31. The blower fan of clause 24, wherein the fan blades and the hub members comprise a metal or a ceramic.32. The blower fan of clause 24, wherein the fan blades are rotated about the axial direction under control of a motor.33. An ultraviolet (UV) light source, comprising: a gas discharge chamber; a cylindrical blower fan located within the gas discharge chamber, the cylindrical blower fan comprising: a plurality of fan blades arranged in a cylindrical form between annular hub members, at least some of the fan blades and the annular hub members having a surface with textures; and electrodes located in the gas discharge chamber; and wherein the cylindrical blower fan is configured to flow a gas mixture between the electrodes, and wherein the textures on the at least some of the surfaces of the fan blades and the annular hub members decrease the amount of drag on the cylindrical blower fan.34. The UV light source of clause 33, wherein each fan blade is fixed to an annular hub member.35. The UV light source of clause 34, wherein each annular hub member and each fan blade has a thickness between 0.5 mm and 1.5 mm, and wherein the textures of the surface with textures on a fan blade or on an annular hub member have a depth of between 0.1 and 0.4 mm into the thickness of the fan blade or the annular hub member.36. The UV light source of clause 33, further comprising a motor, wherein the fan blades are rotated about the axial direction under control of the motor.37. The UV light source of clause 33, wherein the textures of the surface are arranged in a pattern.The above-described implementations and other implementations are within the scope of the following claims.

Claims

CLAIMS1. A gas discharge apparatus of an ultraviolet (UV) light source, the gas discharge apparatus comprising: a gas chamber structure in which a gas discharge chamber is defined; and a blower fan within the gas discharge chamber, the blower fan comprising: a fan mount that is fixed to the gas chamber structure; and a plurality of fan blades arranged in a cylindrical form about an axial direction and a plurality of fan blades arranged longitudinally along the axial direction such that a hollow cylindrical interior is defined, wherein at least some of the fan blades have a surface with textures.

2. The gas discharge apparatus of claim 1, wherein the textures of the surface of the fan blades comprise depressions, and wherein each depression has a depth that is 10-50% of a thickness of the fan blade that includes the depression.

3. The gas discharge apparatus of claim 1, wherein the textures of the surface of the fan blades comprise depressions and each depression has a depth that is 15-25% of a thickness of the fan blade that includes the depression.

4. The gas discharge apparatus of claim 1 , wherein the textures of the surface of the fan blade comprise one or more of depressions and protrusions arranged to cover 10-80% of the total surface of the fan blade.

5. The gas discharge apparatus of claim 1, wherein the blower fan further comprises hub members arranged along the axial direction such that each fan blade extends from one hub member to another hub member.

6. The gas discharge apparatus of claim 5, wherein a surface of at least one hub member has textures.

7. The gas discharge apparatus of claim 5, wherein: each fan blade comprises a connected portion; each fan blade is connected to a hub member at its connected portion; each fan blade comprises a smooth surfaced face; and the surface with textures increases a recirculation flow at a region remote from the connected portion.

8. The gas discharge apparatus of claim 1, wherein at least half of, at least 75% of, or at least 90% of the fan blades include textures at the surface.

9. The gas discharge apparatus of claim 1, wherein the textures of the surface are randomly arranged on the surface.

10. The gas discharge apparatus of claim 1, further comprising: a gas; an anode; and a cathode, wherein the blower fan is configured to blow the gas between the anode and the cathode, and wherein the textures on the at least some of the fan blades having a surface with textures decrease the amount of drag on the fan blades.

11. A blower fan for a gas discharge chamber of an ultraviolet (UV) light source, the blower fan comprising: a fan mount configured to be mounted to a chamber structure of the gas discharge chamber, and a plurality of fan blades arranged in a cylindrical pattern about an axial direction and a plurality of fan blades arranged longitudinally along the axial direction between annular hub members such that a hollow cylindrical interior is defined, wherein at least some of the surfaces of the fan blades and the annular hub members have textures.

12. The blower fan of claim 11, wherein the textures on the surface comprise depressions in the surface or protrusions on the surface, and . wherein each depression on a fan blade has a depth that is 10-50% of a thickness of the fan blade and each protrusion on a fan blade has a height that is 10-50% of the thickness of the fan blade.

13. The blower fan of claim 11, wherein each fan blade extends from an annular hub member, the annular hub members and the fan blades each have a thickness between 0.5 mm and 1.5 mm.

14. The blower fan of claim 11, wherein at least half of, at least 75% of, or at least 90% of the fan blades and the annular hub members include textures at the surface.

15. An ultraviolet (UV) light source, comprising: a gas discharge chamber;a cylindrical blower fan located within the gas discharge chamber, the cylindrical blower fan comprising: a plurality of fan blades arranged in a cylindrical form between annular hub members, at least some of the fan blades and the annular hub members having a surface with textures; and electrodes located in the gas discharge chamber; and wherein the cylindrical blower fan is configured to flow a gas mixture between the electrodes, and wherein the textures on the at least some of the surfaces of the fan blades and the annular hub members decrease the amount of drag on the cylindrical blower fan.

16. The UV light source of claim 15, wherein the textures of the surface with textures on a fan blade or on an annular hub member have a depth of between 0.1 and 0.4 mm into a thickness of the fan blade or the annular hub member.

17. The UV light source of claim 15, wherein the textures of the surface are arranged in a pattern.

Images