Conductive member for discharge laser
Patent Information
- Authority / Receiving Office
- KR · KR
- Patent Type
- Patents
- Current Assignee / Owner
- CYMER INC
- Filing Date
- 2020-09-25
- Publication Date
- 2026-07-29
Smart Images
Figure 112024055573140-PAT00008_ABST
Abstract
Description
Technology Field
[0001] Cross-reference regarding related applications
[0002] This application claims priority to U.S. Application No. 62 / 914,359, filed on October 11, 2019, titled “CONDUCTIVE MEMBER FOR DISCHARGE LASER”, the entire contents of which are incorporated herein by reference.
[0003] The present invention relates to a conductive member, an associated device, a system, and a method for conducting a current associated with an electric discharge within a laser discharge chamber. Background Technology
[0004] A lithography device is a machine configured to apply a desired pattern to a substrate. A lithography device can be used, for example, in the manufacture of integrated circuit ICs. A lithography device can project a pattern (also called a "design layout" or "design") from a patterning device (e.g., a mask) onto a layer of radiation pre-sensitized material (resist) provided on a substrate (e.g., a wafer).
[0005] As semiconductor manufacturing processes continue to advance, the number of circuit elements, such as transistors, per device has steadily increased over decades, following a trend generally known as "Moore's Law," while the dimensions of functional elements have continued to decrease. To sustain Moore's Law, the semiconductor industry is seeking technologies that enable the creation of increasingly smaller features. To project patterns onto a substrate, lithography devices can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the features patterned on the substrate. Lower wavelengths allow for the creation of smaller features on the substrate. Commonly used wavelengths currently are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm. While a lithography device using deep ultraviolet (DUV) radiation can operate at a wavelength of 193 or 248 nm, a lithography device using extreme ultraviolet (EUV) radiation can operate at a wavelength within the range of 4 nm to 20 nm, for example, 6.7 nm or 13.5 nm.
[0006] Gas discharge lasers can be used to generate DUV radiation. In such lasers, the cathode and anode are typically spaced apart within the laser chamber. When an electric discharge is generated between the cathode and anode, current can flow from the cathode to the anode. This current can cause wear on the cathode and / or anode, and this wear may not be uniform. If the cathode and / or anode wear unevenly, the lifespan of the cathode and / or anode, and consequently the laser chamber, may be shortened.
[0007] According to one aspect of the present invention, a conductive member is provided for conducting a current associated with an electric discharge within a discharge chamber of a laser, the conductive member comprising at least one channel configured to increase the current flow path within one part of the conductive member relative to the current flow path within another part of the conductive member, wherein the conductive member is configured to connect the laser to a voltage source and provide an interface between the voltage source and the discharge chamber of the laser. By increasing the current flow path within one part of the conductive member relative to the current flow path within another part of the conductive member, the current density or uniformity of current flow delivered through the conductive member may be increased. It has been found that the uniformity of the current profile within the discharge chamber may then be improved. When the uniformity of the current profile within the discharge chamber is improved, the cathode and anode wear more uniformly, and thus the lifespan of the cathode, anode and / or the discharge chamber of the laser may be increased.
[0008] A conductive member may include a plurality of channels. Each of the channels may be associated with a portion of the conductive member. Each of the channels may be configured to increase the current flow path within the associated portion of the conductive member relative to the current flow path within another portion of the conductive member.
[0009] The conductive member may include a first end. The first end may include at least one channel among the channels.
[0010] The first end may include a first rounded edge. The first end may include at least two channels. At least two of the channels may extend longitudinally inward from the first rounded edge.
[0011] The conductive member may include a second end. The second end may include at least one channel among the channels.
[0012] The second end may include a second round edge. The second end may include at least two channels. At least two of the channels may extend longitudinally inward from the second round edge.
[0013] A conductive member may be configured to be connected to a plurality of charge storage devices. A conductive member may be configured to be connected to a plurality of conductive elements. The conductive member may be configured to conduct current from each of the plurality of charge storage devices to each of the plurality of conductive elements.
[0014] A conductive member may include a plurality of first connection points. A conductive member may include a plurality of second connection points. Each of the plurality of first connection points may be configured to be connected to one of a plurality of charge storage devices. Each of the plurality of second connection points may be configured to be connected to one of a plurality of conductive elements.
[0015] Multiple first connection points may be arranged in a configuration extending longitudinally along the conductive member. Multiple second connection points may be arranged in a configuration extending longitudinally along the conductive member.
[0016] The conductive member may be configured such that each channel of the channels is positioned between the first connection point and the second connection point.
[0017] The conductive member may further include an insulating member. The insulating member may be disposed within each channel.
[0018] The conductive member may be a conductive bar or include a conductive bar.
[0019] According to another aspect of the present invention, a laser is provided comprising a conductive member for conducting a current associated with an electric discharge in a discharge chamber and a discharge chamber, the conductive member comprising at least one channel configured to increase a current flow path in one part of the conductive member relative to a current flow path in another part of the conductive member, wherein the conductive member is configured to connect the laser to a voltage source and provide an interface between the voltage source and the discharge chamber of the laser.
[0020] The laser may include a plurality of charge storage devices. The laser may include a plurality of conductive elements. The plurality of charge storage devices and the plurality of conductive elements may be connected to a conductive member.
[0021] The conductive member may be configured to conduct current from each of the charge storage devices of the plurality of charge storage devices to each of the conductive elements of the plurality of conductive elements.
[0022] Multiple conductive elements can be configured to direct current into the discharge chamber.
[0023] A conductive member may include a plurality of channels. Each of the channels may be associated with a portion of the conductive member. Each of the channels may be configured to increase the current flow path within the associated portion of the conductive member relative to the current flow path within another portion of the conductive member.
[0024] The discharge chamber may be configured to hold one or more gases. One or more gases may include krypton, argon, and / or fluorine.
[0025] Any feature of the non-conductiveness of the preceding modality may be applied to the non-conductiveness of this modality or may be included within the non-conductiveness.
[0026] According to another aspect of the present invention, a lithography system is provided, comprising: a radiation source including a laser, wherein the laser includes a discharge chamber and a conductive member for conducting a current associated with an electric discharge within the discharge chamber according to any of the aforementioned aspects; and a lithography device.
[0027] According to another aspect of the present invention, a method for operating a laser is provided, wherein the laser comprises: a laser having a laser discharge chamber; and a conductive member for conducting a current associated with an electric discharge within the discharge chamber, wherein the conductive member comprises at least one channel configured to increase a current flow path within one part of the conductive member relative to a current flow path within another part of the conductive member, wherein the conductive member connects the laser to a voltage source and provides an interface between the voltage source and the discharge chamber of the laser, and the method comprises the step of applying a voltage to the conductive member to cause an electric discharge within the discharge chamber so that a current associated with an electric discharge flows into the discharge chamber through the conductive member.
[0028] The laser may include a plurality of charge storage devices. The laser may include a plurality of conductive elements. The plurality of charge storage devices and the plurality of conductive elements may be connected to a conductive member.
[0029] The conductive member may be configured to conduct current from each of the charge storage devices of the plurality of charge storage devices to each of the conductive elements of the plurality of conductive elements. The plurality of conductive elements may be configured to direct the current into the discharge chamber.
[0030] The step of applying voltage to the conductive member may cause current to flow from the plurality of charge storage devices through the conductive member to the plurality of conductive elements such that the current flow path from one of the plurality of charge storage devices within a part of the conductive member to the associated conductive element among the plurality of conductive elements is longer than the current flow path from one of the plurality of charge storage devices within the remaining part of the conductive member to the associated conductive element among the plurality of conductive elements.
[0031] The step of applying voltage to the conductive member can cause current to flow from the plurality of conductive elements into the discharge chamber.
[0032] The step of applying voltage to the conductive member may include applying a negative potential to the conductive member.
[0033] A conductive member may include a plurality of channels. Each of the channels may be associated with a portion of the conductive member. Each of the channels may be configured to increase the current flow path within the associated portion of the conductive member relative to the current flow path within another portion of the conductive member.
[0034] The above conductive member may further include an insulating member disposed within each channel.
[0035] Any feature of the non-conductiveness of the preceding modality may be applied to the non-conductiveness of this modality or may be included within the non-conductiveness.
[0036] Various embodiments and features of the present invention described above or below may be combined with other embodiments and / or features of the present invention as will be readily and clearly understood by those skilled in the art. Brief explanation of the drawing
[0037] Embodiments of the present invention will be described only in the manner exemplified below with reference to the attached schematic drawings: FIG. 1 illustrates a schematic overview of a lithography system including a radiation source and a lithography device; FIG. 2 shows a cross-sectional view of a portion of a laser that can be used in the lithography system of FIG. 1; FIGS. 3a and 3b illustrate exemplary embodiments of a conductive member for use with the laser of FIG. 2; FIG. 4a shows a plan view of the conductive member of FIG. 3a; FIG. 4b illustrates a first end of one embodiment of the conductive member of FIG. 4a; FIG. 4c illustrates a first end of another exemplary conductive member for use with the laser of FIG. 2; FIG. 5 shows a partial unfolded view of a laser chamber including a portion of the laser of FIG. 2; FIG. 6 shows a cross-sectional view of a portion of the laser of FIG. 5; Fig. 7 illustrates a portion of the laser of Fig. 5; and Figure 8 shows a flowchart outlining the steps of a method for operating a laser. Specific details for implementing the invention
[0038] FIG. 1 schematically illustrates a lithography system including a radiation source (SO) and a lithography device (LA). A lithography device (LA) comprises an illumination system (also called an illuminator (IL)) configured to control a radiation beam (B) (e.g., UV radiation or DUV radiation or EUV radiation), a mask (e.g., mask table) (MT) connected to a first positioner (PM) configured to support a patterning device (e.g., mask) (MA) and to accurately position the patterning device (MA) according to specific parameters, a substrate support (e.g., wafer table) (WT) connected to a second positioner (PW) configured to hold a substrate (e.g., resist-coated wafer) (W) and to accurately position the substrate support according to specific parameters, and a projection system (e.g., refractive projection lens system) (PS) configured to project a pattern imparted to the radiation beam (B) by the patterning device (MA) onto a target portion (C) (e.g., including one or more dies) of the substrate (W).
[0039] In operation, the illumination system (IL) receives a radiation beam from a radiation source (SO) through a beam delivery system (BD). The illumination system (IL) may include various types of optical components for directing, shaping, or controlling radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and / or other types of optical components, and / or any combination thereof. The illuminator (IL) may be used to adjust the radiation beam (B) so that it has a desired spatial and angular intensity distribution in its cross-section on the plane of the patterning device (MA).
[0040] The term “projection system (PS)” as used herein shall be broadly interpreted to include various types of projection systems, including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic, and / or electrostatic optical systems, and / or any combination thereof, which are suitable for the exposure radiation being used or for other factors such as the use of immersion liquid or vacuum. Any use of the term “projection lens” in this specification may be considered to have the same meaning as the more general term “projection system (PS).”
[0041] The lithography apparatus (LA) may be of a type in which at least a portion of the substrate can be covered by a liquid having a relatively high refractive index, such as water, to fill the space between the projection system (PS) and the substrate (W), and this is also called immersion lithography. More information regarding immersion techniques is provided in US 6,952,253, which is incorporated herein by reference.
[0042] The lithography device (LA) may be of a type having two or more substrate supports (WT) (also called a "dual stage"). In such a "multi-stage" machine, the substrate supports (WT) may be used in parallel, and / or steps for preparing subsequent exposure of a substrate (W) may be located on one of the substrate supports (WT), while another substrate (W) on another substrate support (WT) is used to expose a pattern on the other substrate (W).
[0043] In addition to the substrate support (WT), the lithography device (LA) may include a measurement stage. The measurement stage is configured to hold a sensor and / or a cleaning device. The sensor may be configured to measure the properties of the projection system (PS) or the properties of the radiation beam (B). The measurement stage may hold multiple sensors. The cleaning device may be configured to clean a part of the lithography device, for example, a part of the projection system (PS) or a part of the system providing the immersion solution. The measurement stage may move under the projection system (PS) when the substrate support (WT) moves away from the projection system (PS).
[0044] During operation, a radiation beam (B) is incident on a mask (MA) held by a patterning device, for example, a support structure (MT), and is patterned by a pattern (design layout) on the patterning device (MA). As it crosses the patterning device (MA), the radiation beam (B) passes through a projection system (PS) that focuses the beam onto a target portion (C) of a substrate (W). With the help of a second positioner (PW) and a position measurement system (IF), the substrate support (WT) can be moved precisely to position, for example, different target portions (C) in the path of the radiation beam (B) at a focused and aligned position. Similarly, a first positioning device (PM) and possibly other position sensors (not clearly depicted in FIG. 1) can be used to accurately position the patterning device (MA) with respect to the path of the radiation beam (B). The patterning device (MA) and the substrate (W) can be aligned using mask alignment marks (M1, M2) and substrate alignment marks (P1, P2). Although the substrate alignment marks (P1, P2) occupy dedicated target portions as illustrated, they may also be located in the space between the target portions. When the substrate alignment marks (P1, P2) are located between the target portions (C), they are known as scribe lane alignment marks.
[0045] FIG. 2 illustrates a portion of a laser (10) to be used within a lithography system, such as the lithography system illustrated in FIG. 1, for example. The laser (10) may be part of a radiation source (SO) or may be contained within a radiation source. The laser (10) may be provided in the form of a gas discharge laser, such as an excimer laser, for example. The laser (10) includes a discharge chamber (12). The laser (10) includes a first electrode (14), which may be a cathode. The laser (10) includes a second electrode (16), which may be an anode. The cathode (14) and the anode (16) are placed within the discharge chamber (12). The cathode (14) and the anode (16) are placed in a spaced-apart relationship and facing each other. The anode (16) may be placed facing the cathode (14) on a support member (16b). The support member (16b) may be provided in the form of an anode support bar. In other embodiments, other configurations may be used to determine the positions of the first and second electrodes.
[0046] The discharge chamber (12) may be configured to hold one or more gases (18), such as a gas mixture, for example. The gas (18) may include inert gases, such as argon, krypton, or xenon, for example, and reactive gases, such as fluorine or chlorine, for example.
[0047] When a voltage is applied between the cathode (14) and the anode (16), an electric discharge can be generated within the discharge zone (20) between the cathode (14) and the anode (16). The electric discharge can ionize the gas (18) within the chamber (12), which can then lead to a chemical reaction between the gases. For example, a mixture of argon and fluoride gases can chemically generate excited molecules of argon fluoride, which exist only in the excited state and can decay very rapidly. The excited molecules can release their excess energy by emitting photons, thereby returning to their ground state where they dissociate back into free atoms. Then, the photons generated during the electric discharge can be reflected within the chamber by one or more optical components (not shown) and directed from the laser (10) as laser pulses. In other embodiments, it will be understood that other gas mixtures, such as krypton and fluoride gas mixtures, may be used.
[0048] In some embodiments, the gas mixture (18) may be pre-ionized to produce the required electron density prior to the electric discharge. The laser may include a pre-ionization device (21), which may be configured to generate ultraviolet radiation to ionize the gas mixture (18) prior to the electric discharge.
[0049] The laser (10) may include a plurality of insulating parts or components (19). The insulating parts or components (19) may include a ceramic material, for example, aluminum oxide (Al2O3 or AlO2). Alternatively, the insulating parts or components (19) may include a plastic material that may include a polymer or polymer compound, for example, Teflon. The insulating parts or components (19) may be arranged in various ways within the discharge chamber to electrically insulate the cathode (14) and the anode (16) from other parts of the discharge chamber (12).
[0050] It will be understood that the laser (10) may include one or more of the gases, circulate the gases within the discharge chamber, and other components and / or others for controlling the temperature within the discharge chamber, which are not shown in FIG. 2 for clarification.
[0051] The laser (10) includes a conductive member (22) for conducting a current associated with an electric discharge within a discharge chamber (12). In other words, if an electric discharge is present within the discharge chamber, a current may flow through the conductive member (22). The current may flow into the discharge chamber (12) through the conductive member (22). For example, the current may flow through the conductive member (22) to the cathode (14) and from the cathode (14) to the anode (16) as described below. The conductive member (22) is configured to connect the laser (10) to a voltage source (24) and to provide an interface between the voltage source (24) and the discharge chamber (12) of the laser (10). In other words, a voltage may be applied to the cathode (14) and / or the anode (16) through the conductive member (22). The conductive member (22) may be provided in the form of a conductive bar. The conductive member (22) may include a metal such as aluminum, for example. The conductive member (22) may include a coating. The coating may include a fluorine-resistant material. For example, the coating may include a transition metal such as nickel, for example.
[0052] FIGS. 3a and 3b illustrate exemplary embodiments of a conductive member (22) for use with a laser, such as the laser (10) shown in FIG. 2, for example. The conductive member (22) comprises at least one channel (26) configured to increase the current flow path within a first portion (28) of the conductive member (22) relative to the current flow path within a second portion (30) of the conductive member (22). Alternatively or additionally, the channel (26) may be configured to increase the current flow path within a third portion (32) of the conductive member (22) relative to the current flow path within the second portion (30) of the conductive member (22). In other words, the channel (26a) may be configured to force the current to take a longer flow path within the first portion (28) of the conductive member (22) relative to the current flow path within the second portion (30) of the conductive member (22). Then, the uniformity of the current density or current flow within the conductive member (22) can be increased. Then, it has been found that the uniformity of the current profile within the discharge chamber (12) can be improved. The term "current profile" may be understood to encompass the current and / or current density through the cathode (14) and / or anode (16), for example, along the length of the cathode (14) and / or anode (16). If the uniformity of the current profile within the discharge chamber is improved, the cathode and anode may wear more uniformly, and then the life of the discharge chamber of the cathode, anode and / or laser may be increased.
[0053] The conductive member (22) comprises a plurality of channels (26a to 26d), four of which are illustrated in FIG. 3a and FIG. 3b. However, it will be understood that the number of channels may be selected based on a current profile that may be desired or required within the discharge chamber (12) and / or a desired or required current density within the conductive member (22). In other embodiments, it will also be acknowledged that the conductive member may comprise five or more or three or fewer channels.
[0054] Each of the channels (26a to 26d) may be associated with a first part (28) or a third part (32) of the conductive member (22). Each of the channels (26a to 26d) is configured to increase the current flow path within the associated part of the conductive member (22) relative to the current flow path of the other part of the conductive member, namely the second part (30). In the embodiment illustrated in FIGS. 3a and 3b, two channels (26a, 26b) are associated with the first part (28) of the conductive member (22). Each of the two channels (26a, 26b) may be configured to increase the current flow path within the first part (28) of the conductive member (22) relative to the current flow path within the second part (30) of the conductive member (22). Two additional channels (26c, 26d) may be associated with a third part (32) of the conductive member (22). In other words, each of the two additional channels (26c, 26d) may be configured to increase the current flow path within the third part (32) of the conductive member (22) relative to the current flow path within the second part (30) of the conductive member (22). The first, second, and third parts (28, 30, 32) are indicated by dashed lines in FIG. 3a and FIG. 3b.
[0055] The conductive member (22) may be configured such that two channels (26a, 26b) extend parallel to each other and / or two additional channels (26c, 26d) extend parallel to each other, as shown in FIG. 3a and 3b. Each of the two channels (26a, 26b) and / or each of the two additional channels (26c, 26d) may be positioned to extend along the axial or longitudinal direction A of the conductive member (22).
[0056] Parameters such as the dimensions and structure of the channels (26a, 26b) and two additional channels (26c, 26d) may be selected based on the required current profile within the discharge chamber (12) or the required current density within the conductive member (22). The parameters may include the length L and width W of each channel (26a, 26b) and each additional channel (26c, 26d) as shown in FIG. 3a. The length of each channel (26a, 26b) and / or each additional channel (26c, 26d) may be in the range of about 3 to 20 cm in some embodiments, but other dimensions may be used in other embodiments. The width of each channel (26a, 26b) and / or each additional channel (26c, 26d) may be in the range of about 0.5 to 1.3 cm in some embodiments, but other dimensions may be used in other embodiments. Each of the individual channels (26a to 26d) may have parameters of the same dimension or different dimensions.
[0057] The conductive member (22) may include a first end (34). A first portion (28) of the conductive member (22) may form or be part of the first end (34) of the conductive member (22). In this embodiment, the first end (34) includes two channels (26a, 26b). It will be understood that in other embodiments, the first end may include three or more channels or one channel. The first end (34) may include a first round edge (34a). The conductive member (22) may be configured such that the two channels (26a, 26b) extend longitudinally inward from the first round edge (34a).
[0058] The conductive member (22) may include a second end (36). A third portion (32) of the conductive member (22) may form or be part of the second end (36) of the conductive member (22). In this embodiment, the second end (36) includes two additional channels (26c, 26d). It will be understood that in other embodiments, the second end may include three or more or one additional channel. The second end (36) may include a second round edge (36a). The conductive member (22) may be configured such that the two additional channels (26c, 26d) extend longitudinally inward from the second round edge (36a). One or all of the channels (26a to 26d) may extend longitudinally inward from one of the first and second round edges (34a, 36a). The conductive member (22) is configured such that the first and second round edges (34a, 36a) face each other.
[0059] Experimental results revealed that without the channels (26a-26d), an increased current may flow within the first and / or second ends (34, 36) compared to the current flowing in the remainder of the conductive member (22), for example, during use. In other words, during use, the current density within the first and / or second ends (34, 36) may be higher than the current density within the remainder of the conductive member (22). By providing the channels (26a, 26b) as part of the first end (34) and / or additional channels (26c, 26d) as part of the second end (36) of the conductive member (22), the current density or current flowing within the first and / or second ends (34, 36) may be reduced. Then, the uniformity of the current density or current flowing through the conductive member (22) may be increased. Then, the cathode and anode can wear more uniformly, and then the life of the cathode, anode, and / or discharge chamber can be increased.
[0060] FIG. 3a illustrates an exemplary conductive member (22) that may be used with a discharge chamber (12) containing an argon fluoride gas mixture, but may also be used with other gas mixtures. The conductive member (22) may be configured to conduct a current associated with an electric discharge within the discharge chamber (12), as described above. One or more dimensions of the conductive member (22) may be selected based on a required or desired current profile within the discharge chamber (12). Additionally or alternatively, the dimensions of the conductive member (22) may be selected to minimize or reduce the inductance of the conductive member (22), for example, when current flows through the conductive member (22) during use. Alternatively or additionally, it will be understood that the dimensions may be selected based on one or more dimensions of the discharge chamber (12) and / or other parts of the laser (10). In this embodiment, the conductive member (22) may have a thickness T within the range of 20 to 50 mm, for example, about 30 mm, but in other embodiments, a different thickness may be used. The conductive member (22) further includes two recesses (35a) having a thickness smaller than the thickness T. The conductive member (22) may have a length L1 and a width W1 selected together with the dimensions of the discharge laser and which may vary in various embodiments.
[0061] FIG. 3b illustrates an exemplary conductive member (22) that can be used with a discharge chamber (12) containing a gas mixture such as a krypton fluoride gas mixture, but the exemplary conductive member (22) of FIG. 3b may also be used with other gas mixtures. The conductive member (22) illustrated in FIG. 3b is similar to that illustrated in FIG. 3a. However, it can be seen that the conductive member (22) illustrated in FIG. 3b is thinner than the conductive member (22) illustrated in FIG. 3a. In this embodiment, the conductive member (22) may have a thickness within the range of 2 to 5 mm, for example, about 3 mm, but in other embodiments, a different thickness may be used. The length L1 and width W1 of the conductive member (22) illustrated in FIG. 3b will be selected together with the dimensions of the discharge laser, which may vary in various embodiments.
[0062] FIG. 4a illustrates a plan view of the exemplary conductive member (22) shown in FIG. 3a. However, it will be understood that any feature described below may also be applied to the conductive member (22) shown in FIG. 3b. The conductive member (22) is configured to be connected to a voltage source (24). The conductive member (22) may be configured to accommodate a portion of a connecting device for connecting the voltage source to a laser (not shown in FIG. 4a). The conductive member (22) may include two recesses (35a). The two recesses (35a) may be considered to be recessed downward into the plane of FIG. 4a. The two recesses (35a) are more clearly visible in FIG. 3a. In some embodiments, the recesses (35a) may be configured to accommodate at least a portion of the connecting device. The two recesses (35a) are positioned within the center or middle portion (37) of the conductive member (22). The middle portion (37) of the conductive member (22) may be part of or contained within the second portion (30) of the conductive member (22). Each of the recesses (35a) may be arranged to extend along the axial or longitudinal direction A. The width W2 of the center or middle portion (37) may be greater than the width W1 of the remainder of the conductive member (22) (shown in FIG. 3a). The center or middle portion (37) may be configured to allow a seal to be formed between the conductive member (22) and other parts of the laser (10).
[0063] The conductive member (22) may be configured to be connected to a plurality of charge storage devices and a plurality of conductive elements. For example, each charge storage device may be provided in the form of a capacitor as shown in FIG. 5. However, it will be understood that other devices for storing charge may be used. Each conductive element may be provided in the form of a feedthrough element, but in other embodiments, other conductive elements may be used. The conductive member (22) may be configured to conduct current from each capacitor to each feedthrough.
[0064] Referring to FIG. 4a, the conductive member (22) may include a plurality of first connection points (38). Each first connection point (38) may be configured to be connected to a charge storage device, such as a capacitor. Each first connection point (38) may be provided in the form of a bore. The first connection points (38) are arranged along the axial or longitudinal direction A of the conductive member (22). The first connection points (38) may be arranged near the outer edge or periphery of the conductive member (22). The first connection points (38) may be arranged in two rows (38a, 38b) on opposite sides of the conductive member (22). A portion of the first connection points (38) may be arranged within a recess (35a) as shown in FIG. 4a.
[0065] The conductive member (22) may include a plurality of second connection points (40). Each second connection point (40) may be configured to be connected to a feed-through element. Each first connection point (38) is provided in the form of an additional bore. The second connection points (40) may be arranged linearly along the axial or longitudinal direction A of the conductive member (22), but other configurations may be used in other embodiments. The second connection points (40) may be placed between two rows (38a, 38b) of the first connection points (38). Each second connection point (40) may be associated with a pair of the first connection points (38). Each second connection point (40) may be placed between the associated pair of first connection points (38).
[0066] FIG. 4b illustrates a first end (34) of the conductive member illustrated in FIG. 4a. The conductive member (22) may be configured such that each channel (26a, 26b) extends between a first connection point (38) and a second connection point (40) through which current can flow from an associated first connection point (38). In the exemplary embodiment illustrated in FIG. 4a, each channel (26a, 26b) extends approximately between two first connection points (38) and two second connection points (40). When in use, when the conductive member (22) is connected to a capacitor and a feedthrough element, the conductive member (22) can conduct current from one capacitor or a pair of capacitors to the associated feedthrough element. Current flow paths within the first and second parts (28, 30) of the conductive member are indicated by arrows in FIG. 4a. The current flow path within the first part (28) of the conductive member (22) is longer than the current flow path in the second part (30) as illustrated in FIG. 4b. In other words, the channels (26a, 26b) can be configured to force the current onto the longer flow path within the first part (28) of the conductive member (22) compared to the current flow path within the second part (30) of the conductive member (22). Then, the uniformity of the current flowing through the conductive member (22) or the current density within the conductive member can be increased. Then, a more uniform current or current density can be obtained depending on the cathode (14) and / or anode (14), which can cause the cathode and anode to wear more uniformly. Then, the lifespan of the cathode, anode and / or discharge chamber can be increased.
[0067] FIG. 4c illustrates a first end (34) of another exemplary embodiment of the conductive member (22). The conductive member illustrated in FIG. 4c is similar to the conductive member (22) described above. In this embodiment, the conductive member (22) includes an insulating portion (42). At least a portion of the insulating portion (42) may be placed within each of the two channels (26a, 26b). The insulating portion (42) may be configured to prevent current from flowing across each channel (26a, 26b) or across both channels (26a, 26b). The insulating portion (42) may be configured based on parameters of each channel (26a, 26b) and / or the distance D between the two channels (26a, 26b). In this embodiment, the insulating portion (42) includes a U-shape. In other embodiments, it will be understood that the insulating portion may have different shapes depending, for example, on the parameters of each channel and / or the distance between two channels. In other embodiments, the insulating portion may include two distinct prongs (42a) that are not coupled to each other to form an integral piece. The insulating portion (42) may include two prongs (42a) and / or a portion (42b) connecting the two prongs (42a). The length L3 and / or width W3 of each prong (42a) may be selected based on the length L and / or width W of each channel (26a, 26b). In other words, the length L3 and / or width W3 of each prong (42a) may be selected to correspond approximately to the length L and / or width W of each channel (26a, 26b). The insulating portion (42) may be disposed on the conductive member (22), for example, such that each of the branches (42a) is disposed within each of the two channels (26a, 26b). When each branch (42a) of the insulating portion (42) is disposed within each of the two channels (26a, 26b), the portion (42b) may cover the portion (34b) of the first round edge (34a).The portion (34b) of the first round edge (34a) can be extended between the two channels (26a, 26b).
[0068] The insulating part may be formed of an insulating material. For example, the insulating material may include a plastic material. The plastic material may include a polymer or a polymer compound, such as Teflon, for example. Alternatively, the insulating material may include a ceramic material, such as aluminum oxide (Al2O3 or AlO2). The insulating part (42) may be placed within each channel (26a, 26b) as described above to prevent the formation of an electric arc or arc discharge within each channel (26a, 26b) and / or between two channels (26a, 26b). It will be understood that the conductive member (22) may include an additional insulating part. The additional insulating part may include any of the features of the insulating part (42). The additional insulating part may be placed within each additional channel (26c, 26d). The conductive member (22) may include an insulating part placed within one or more of the channels (26a to 26d). One or all of the channels (26a to 26d) may include an insulating portion disposed therein.
[0069] FIG. 5 is a cross-sectional view showing an exemplary embodiment of a laser (10). The laser (10) includes a portion of the laser shown in FIG. 2. As such, any feature described in relation to FIG. 2 may also be applied to the laser (10) shown in FIG. 5.
[0070] FIG. 5 shows an outer portion (12a) of the discharge chamber (12) shown in FIG. 2. The outer portion (12a) of the discharge chamber (12) may be provided in the form of a recess on the outer surface of the discharge chamber (12). As previously described, the laser (10) includes a conductive member (22). The conductive member (22) is configured to be attached to the outer portion (12a) of the discharge chamber. The conductive member (22) shown in FIG. 5 is identical to the conductive member (22) shown in FIG. 4a and FIG. 4b. As such, any feature described in relation to FIG. 4a and FIG. 4b may also be applied to the conductive member (22) shown in FIG. 5.
[0071] The laser (10) includes a plurality of charge storage devices (44), which are provided in the form of a plurality of capacitors. Each capacitor (44) may have a capacitance within the range of 200 to 800 pF, but in other embodiments, a different capacitance may be used. The arrangement of the capacitors (44) may correspond to the arrangement of the first connection points (38) of the conductive member (22). In other words, the capacitors (44) may be arranged along the axial or longitudinal direction B of the laser (10). The capacitors (44) may be arranged within two rows (44a, 44b) on opposite sides of the outer part (12a) of the discharge chamber (12). The capacitors (44) may be connected to the conductive member (22) using, for example, a plurality of conductive fasteners (46a), such as screws, pins, bolts, etc., one of which is shown in FIG. 5. Each fastener (46a) can be inserted into the first connection point to connect the capacitor to the conductive member (22).
[0072] The laser (10) includes a plurality of conductive elements (48) provided as a plurality of feedthrough elements. The arrangement of the feedthrough elements (48) may correspond to the arrangement of the second connection points (40) of the conductive member (22). In other words, the feedthrough elements (48) may be arranged linearly along the axial or longitudinal direction B of the laser (10) as shown in FIG. 5. In other embodiments, a different arrangement may be used. The feedthrough elements (48) may be placed between two rows (44a, 44b) of the capacitor (44). The feedthrough elements (48) may be connected to the conductive member (22), for example, using a plurality of additional conductive fasteners (46b), such as screws, pins, bolts, etc., one of which is shown in FIG. 5. Each additional fastener (46b) can be inserted into the second connection point to connect the feedthrough element (48) to the conductive member (22), but other fastening means may also be used.
[0073] In some embodiments, the laser (10) may include an optional connecting member (45). The connecting member (45) may be provided in the form of a connecting plate or an interconnecting plate. The connecting plate (45) may be configured to be flexible. For example, the connecting plate (45) may have a thickness of less than 1 mm, but in other embodiments, a different thickness is used. The connecting plate (45) may include a conductive material. The conductive material may include a metal or a metal alloy, such as copper or brass, for example. The connecting plate (45) may be placed between the conductive member (22), the capacitor (44), and the feedthrough element (48). The connecting plate (45) may have the same or similar shape and configuration as the conductive member (22) containing the channel. In FIG. 5, two channels (45a and 45b) corresponding to two channels within the conductive member (22) can be seen. It will be understood that the number of channels within the connecting plate (45) may correspond to the number of channels within the conductive member (22). The connecting plate (45) may be positioned to ensure contact between the conductive member (22), the capacitor (44), and the feed-through element (48). The connecting plate (45) may include a plurality of additional bores (45a) to allow the capacitor (44) and the feed-through element (48) to be connected to the conductive member (22) through the connecting plate (45), for example.
[0074] The laser (10) may include a connecting device (47), for example, a conductive member (22), for connecting a voltage source (not shown in FIG. 5) to the laser (10). The connecting device (47) includes at least two connecting elements (47a). Each connecting element (47) may include a conductive material, for example, metal. Each connecting element (47a) may be placed within each recess (35a) of the conductive member (22). The connecting element (47a) may be secured to the conductive member (22) by a plurality of other fasteners (47b), for example, screws, pins, bolts, etc. The connecting device (47) may include at least two additional connecting elements (47c). The two additional connecting elements (47c) may each be provided in the form of elastic and / or flexible elements, such as springs or coil springs. Each additional connecting element (47c) may be placed within the recess (47d) of each connecting element (47a). The connecting element (47a) and the additional connecting element (47c) may comprise a conductive material. The conductive material may comprise a metal or metal alloy, such as, for example, tin, brass, copper, etc. The connecting device (47) may comprise at least two sealing elements (47e), such as, for example, two gaskets. Each sealing element (47e) may be positioned to surround the connecting element (47a) and / or the additional connecting element (47c). In other words, each sealing element (47e) may be positioned between the conductive member (22) and the connecting element (47a) and / or the additional connecting element (47c). The connecting device (47) may be provided to ensure contact between the voltage source and the conductive member (22). It will be understood that in other embodiments, any of various other means for coupling a voltage source to a conductive member may be used.
[0075] FIG. 6 illustrates a cross-sectional view of a portion of the laser (10) along line B of FIG. 5. The cathode (14) and anode (16) of the laser (10) may be configured to extend along the axial or longitudinal direction of the laser (10). The anode (16) is attached to a support member (16b) by a plurality of fixing elements (16c), which may be provided in the form of screws, pins, bolts, etc. Three feed-through elements (48) shown in FIG. 6 may be configured to direct current into the discharge chamber (12). For example, the feed-through elements (48) may be connected to the cathode (14) of the laser (10). Each feed-through element (48) may be positioned to extend from an outer portion (12a) of the discharge chamber (12) into the discharge chamber (12). This allows voltage to be applied to the cathode (14) through the conductive member (22) and the feedthrough element (48) as described below. Each feedthrough element (48) may be configured to seal at least a portion of the discharge chamber (12) to prevent, for example, gas (18) from leaking out of the discharge chamber (12). Each feedthrough element (48) may include a fluorine-resistant material. The fluorine-resistant material may include a metal alloy, for example, brass.
[0076] FIG. 7 shows a portion of the laser (10) illustrated in FIG. 5. As previously described, if an electric discharge exists between the cathode (14) and the anode (16), current may flow through one or more portions of the laser (10). The path of current flow is indicated by an arrow in FIG. 7.
[0077] As described above, a voltage source (24) may be connected to a conductive member (22). In use, voltage is applied to the conductive member (22) to cause an electric discharge within the discharge chamber, so that a current associated with the electric discharge flows through the conductive member (22) into the discharge chamber (12). The voltage applied to the conductive member (22) may be within the range of 500 to 1500V.
[0078] The conductive member (22) may be connected to a capacitor (44) and a feedthrough element (48). When a voltage is connected to the conductive member (22), each capacitor (44) may be charged. Charging of each capacitor (44) may cause the voltage between the cathode (14) and the anode (16) to increase. This voltage may be applied to the cathode (14) through the feedthrough element (48). For example, a negative potential may be applied to the conductive member (22), which causes the feedthrough element (48) and the cathode (14) to be negatively charged. The negative potential applied to the conductive member (22) may also cause at least some of each capacitor (44) to be negatively charged. Then, an electric field may be generated between the cathode (14) and the anode (16) connected to ground. In other embodiments, a positive potential may be applied to the anode. The electric field can ionize the gas mixture (18) between the cathode (14) and the anode (16). When the gas mixture (18) is sufficiently ionized, gas breakdown may occur and an electric discharge may be generated within the discharge zone (20) of the discharge chamber (12). This may result in a voltage drop (VCP) between each of the capacitors (44) and a voltage drop between the cathode (14) and the anode (16). Current may flow from the capacitor (44) through the conductive member (22) to the feedthrough element (48). From the feedthrough element (48), current may flow into the discharge chamber (12), for example, to the cathode (14) and through the discharge zone (20) to the anode (16). By configuring the conductive member (22) to include at least one channel, the current density or uniformity of current flow within the conductive member (22) may be increased as described above. Then, the uniformity of the current or current density can now be increased along the cathode (14) and the anode (16), for example, along the length of the cathode (14) and / or the anode (16).When the uniformity of the current or current density is increased in this way, the cathode and anode can wear more uniformly, which can increase the lifespan of the cathode, anode, and / or the laser discharge chamber. The current can be diverted from the anode (16) to ground (not shown), for example, using a current recovery element (54). The current recovery element (54) can be configured to connect the anode (16) to ground.
[0079] FIG. 8 is a flowchart schematically showing the steps of a method for operating a laser, e.g., the aforementioned laser (10). In step 105, this method includes the step of providing a conductive member (22) and a voltage source as described above to the discharge laser.
[0080] In step 110, this method includes the step of applying voltage to a conductive member using a voltage source. The voltage is applied to cause an electric discharge within the discharge chamber of the laser, thereby operating the laser to generate a laser beam as described above.
[0081] In step 115, the voltage applied to the conductive member causes current to flow through the conductive member from the laser's charge storage device, e.g., capacitor (44), to the laser's conductive element, e.g., feedthrough element (48).
[0082] In step 120, the voltage applied to the conductive member causes current to flow from the feedthrough element (48) into the discharge chamber. For example, current may flow from the conductive element to the first electrode of the laser, for example, the cathode (14). From the first electrode of the laser, current may flow through, for example, the discharge zone (20) to the second electrode of the laser, for example, the anode (16).
[0083] The step of applying voltage may include charging a charge storage device, e.g., a capacitor (44), and / or a conductive element. For example, as described above, a negative potential may be applied to the conductive member. Then, at least a portion of the conductive member, the conductive element, and each charge storage device may be negatively charged. Then, the first electrode of the laser, e.g., the cathode, may be negatively charged.
[0084] This method may include, for example, a step of pre-ionizing the gas mixture within the laser discharge chamber prior to the electric discharge.
[0085] For example, it will be understood that any feature described above in relation to Fig. 7 may be applied to this method or part thereof.
[0086] As described above, by forming a channel within the conductive member, uneven wear of the cathode and / or anode can be reduced or prevented. Since the conductive member can be connected to the discharge chamber on an external portion, it may not be exposed to fluorine when separating the conductive member from the external portion of the discharge chamber and / or (re)attaching the conductive member to the external portion of the discharge chamber. Additionally, the formation of the channel as described above may have a reduced or no effect on one or more structural or thermal properties of the conductive member.
[0087] The term "channel" can be regarded as encompassing a long recess or a long hollow space or part.
[0088] It will be understood that the terms "current flow path" and "path of current flow" can be used interchangeably.
[0089] It will be understood that referring to multiple features may be used interchangeably with referring to the singular forms of such features, such as, for example, "at least one" and / or "each." For example, the singular forms of features, such as "at least one" or "each," may be used interchangeably.
[0090] In this specification, the terms “radiation” and “beam” are used to encompass all types of electromagnetic radiation, including ultraviolet radiation (e.g., radiation having wavelengths of 365, 248, 193, 157, or 126 nm) and EUV (e.g., extreme ultraviolet radiation having wavelengths in the range of about 5-100 nm).
[0091] As used herein, the terms “reticle,” “mask,” or “patterning device” may be broadly interpreted to refer to a general patterning device that can be used to impart a patterned cross-section corresponding to a pattern to be formed within a target portion of a substrate to an incoming radiation beam. The term “optical valve” may also be used in this context. In addition to traditional masks (transmissive or reflective; binary, phase-shift, hybrid, etc.), other examples of such patterning devices include programmable mirror arrays and programmable (LCD) arrays.
[0092] While the use of lithography devices in the field of manufacturing ICs may be specifically mentioned in this specification, it should be understood that the lithography devices described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memory, flat panel displays, Liquid Crystal Displays (LCDs), thin film magnetic heads, etc.
[0093] Although embodiments of the present invention have been specifically referenced in the context of a lithography device herein, embodiments of the present invention may be used in other devices or systems. Embodiments of the present invention may be part of a mask inspection device, a metrology device, or any device that measures or processes an object such as a wafer (or other substrate) or a mask (or other patterning device). Such devices may generally be referred to as lithography tools. Such lithography tools may use vacuum conditions or ambient (non-vacuum) conditions.
[0094] Although specific references have been made above regarding the use of embodiments of the present invention in the context of optical lithography, it will be acknowledged that, where the context permits, the present invention is not limited to optical lithography and may be used in other applications, e.g., imprint lithography.
[0095] Various aspects of the present invention are described in the following numbered sections.
[0096] 1. A conductive member for conducting a current associated with an electric discharge within a laser discharge chamber,
[0097] It includes at least one channel configured to increase the current flow path within one part of the conductive member relative to the current flow path within another part of the conductive member, and
[0098] The conductive member is configured to connect the laser to a voltage source and provide an interface between the voltage source and the discharge chamber of the laser.
[0099] 2. In Section 1,
[0100] The above conductive member is a conductive member comprising a plurality of channels.
[0101] 3. In Section 2,
[0102] A conductive member, wherein each of the above channels is associated with one part of the conductive member and is configured to increase the current flow path within the associated part of the conductive member relative to the current flow path within another part of the conductive member.
[0103] 4. In any one of Sections 1 through 3,
[0104] The above conductive member includes a first end, and
[0105] The first end portion comprises a conductive member including at least one of the channels.
[0106] 5. In Section 4,
[0107] The above-mentioned first end includes a first rounded edge, and
[0108] A conductive member comprising at least two of the channels, the first end extending longitudinally inward from the first round edge.
[0109] 6. In Section 4 or Section 5,
[0110] The above conductive member includes a second end, and
[0111] The second end portion comprises a conductive member including at least one of the channels.
[0112] 7. In Section 6,
[0113] The above-mentioned second end includes a second round edge, and
[0114] A conductive member comprising at least two of the channels, the second end extending longitudinally inward from the second round edge.
[0115] 8. In any one of Sections 1 through 7,
[0116] The conductive member is configured for connection to a plurality of charge storage devices and a plurality of conductive elements.
[0117] 9. In Section 8,
[0118] The conductive member is configured to conduct current from each of the plurality of charge storage devices to each of the plurality of conductive elements.
[0119] 10. In Section 8 or 9,
[0120] The conductive member includes a plurality of first connection points and a plurality of second connection points, and
[0121] Each of the plurality of first connection points is configured for connection to one of the plurality of charge storage devices, and
[0122] A conductive member, wherein each of the plurality of second connection points is configured to be connected to one of the plurality of conductive elements.
[0123] 11. In Section 10,
[0124] A conductive member, wherein the plurality of first connection points and / or the plurality of second connection points are each arranged in a configuration extending longitudinally along the conductive member.
[0125] 12. In Section 10 or Section 11,
[0126] The conductive member is configured such that each channel of the channels is disposed between the first connection point and the second connection point.
[0127] 13. In any one of Sections 1 through 12,
[0128] The above conductive member is,
[0129] A conductive member further comprising an insulating portion disposed within each channel.
[0130] 14. In any one of Sections 1 through 13,
[0131] The above conductive member is a conductive member comprising a conductive bar.
[0132] 15. As a laser,
[0133] Discharge chamber; and
[0134] It includes a conductive member for conducting a current associated with an electric discharge within the above-mentioned discharge chamber,
[0135] The above conductive member is,
[0136] It includes at least one channel configured to increase the current flow path within one part of the conductive member relative to the current flow path within another part of the conductive member, and
[0137] A laser, wherein the conductive member is configured to connect the laser to a voltage source and provide an interface between the voltage source and the discharge chamber of the laser.
[0138] 16. In Section 15,
[0139] The above laser includes a plurality of charge storage devices and a plurality of conductive elements, and
[0140] A laser, wherein the plurality of charge storage devices and the plurality of conductive elements are connected to the conductive member.
[0141] 17. In Section 16,
[0142] The above conductive member is a laser configured to conduct current from each of the plurality of charge storage devices to each of the plurality of conductive elements.
[0143] 18. In Section 16 or 17,
[0144] A laser, wherein the plurality of conductive elements are configured to direct current into the discharge chamber.
[0145] 19. In any one of Sections 15 through 18,
[0146] The above conductive member includes a plurality of channels, and
[0147] A laser, wherein each of the above channels is associated with one part of the conductive member and is configured to increase the current flow path within the associated part of the conductive member relative to the current flow path within another part of the conductive member.
[0148] 20. In any one of Sections 15 through 19,
[0149] The above discharge chamber is configured to hold one or more gases, and
[0150] One or more of the above gases include krypton, argon and / or fluorine, laser.
[0151] 21. As a lithography system,
[0152] A radiation source including a laser - the laser,
[0153] Discharge chamber; and
[0154] Comprising a conductive member for conducting a current associated with an electric discharge within a discharge chamber according to any one of Sections 1 through 14; and
[0155] A lithography system comprising a lithography device.
[0156] 22. As a method for operating a laser,
[0157] The above laser is,
[0158] A laser having a laser discharge chamber; and
[0159] It includes a conductive member for conducting a current associated with an electric discharge within a discharge chamber, and
[0160] The conductive member comprises at least one channel configured to increase the current flow path within one part of the conductive member relative to the current flow path within another part of the conductive member, and
[0161] The conductive member connects the laser to a voltage source and provides an interface between the voltage source and the discharge chamber of the laser, and
[0162] The above method is,
[0163] A laser operating method comprising the step of applying a voltage to a conductive member to cause an electric discharge in the discharge chamber, so that a current associated with the electric discharge flows into the discharge chamber through the conductive member.
[0164] 23. In Section 22,
[0165] The above laser includes a plurality of charge storage devices and a plurality of conductive elements, and
[0166] A laser operating method in which the plurality of charge storage devices and the plurality of conductive elements are connected to the conductive member.
[0167] 24. In Section 23,
[0168] The conductive member is configured to conduct current from each of the charge storage devices of the plurality of charge storage devices to each of the conductive elements of the plurality of conductive elements, and
[0169] A laser operating method in which the plurality of conductive members are configured to direct current into the discharge chamber.
[0170] 25. In Section 23 or 24,
[0171] A laser operating method in which the step of applying voltage to the conductive member causes current to flow from the plurality of charge storage devices through the conductive member to the plurality of conductive elements such that the current flow path from one of the plurality of charge storage devices within a part of the conductive member to an associated conductive element among the plurality of conductive elements is longer than the current flow path from one of the plurality of charge storage devices within the remaining part of the conductive member to an associated conductive element among the plurality of conductive elements.
[0172] 26. In Section 25,
[0173] A laser operating method in which the step of applying voltage to the conductive member causes current to flow from the plurality of conductive elements into the discharge chamber.
[0174] 27. In any one of Sections 23 through 26,
[0175] A laser operating method, wherein the step of applying voltage to the conductive member comprises applying a negative potential to the conductive member.
[0176] 28. In any one of Sections 22 through 27,
[0177] The above conductive member includes a plurality of channels, and
[0178] A laser operating method wherein each of the above channels is associated with one part of the conductive member and is configured to increase the current flow path within the associated part of the conductive member relative to the current flow path within another part of the conductive member.
[0179] 29. In any one of Sections 22 through 29,
[0180] A laser operating method wherein the conductive member further comprises an insulating portion disposed within each channel.
[0181] Although specific embodiments of the present invention have been described above, it will be understood that the invention may be practiced differently from that described. The above description is provided for illustrative purposes only and not for limiting purposes. Accordingly, it will be apparent to those skilled in the art that modifications to the invention as described may be made without departing from the scope of the claims set forth below.
Claims
Claim 1 A light source system comprising: a discharge chamber having a pair of electrodes, wherein at least some of the electrodes are located within the discharge chamber; and a conductive member extending along the longitudinal direction and electrically connected to a first electrode of the pair of electrodes, wherein the conductive member has a first recess extending along the longitudinal direction. Claim 2 A light source system according to claim 1, wherein the first recess extends from one end of the conductive member toward the center of the conductive member. Claim 3 A light source system according to claim 1, further comprising a second recess arranged parallel to the first recess, wherein the second recess and the first recess are symmetric with respect to a first centerline of a conductive member, and the first centerline extends along the length direction. Claim 4 A light source system according to paragraph 3, further comprising a third recess and a fourth recess arranged on the remaining end of the conductive member, wherein the third recess and the fourth recess are symmetric to the first recess and the second recess along a second centerline of the conductive member, and the second centerline is perpendicular to the first centerline. Claim 5 A light source system according to claim 1, wherein the first recess is filled with an insulating material. Claim 6 In claim 1, the first recess is a light source system without insulating material. Claim 7 A light source system according to claim 1, further comprising a first row of capacitors connected to the conductive member, a second row of capacitors connected to the conductive member, and a row of feedthroughs connected to the conductive member and arranged along the longitudinal direction, wherein the row of feedthroughs is located between the first row of capacitors and the second row of capacitors. Claim 8 In claim 7, the conductive member is electrically connected to the row of feedthroughs, in a light source system. Claim 9 In claim 7, the light source system, wherein the first recess is arranged between the first row of capacitors and the row of feedthroughs. Claim 10 A conductive member configured to conduct a current associated with an electric discharge of a laser, comprising: a first plurality of openings arranged in a first row extending along the longitudinal direction of the conductive member; a second plurality of openings arranged in a second row extending parallel to the first row; a third plurality of openings arranged in a third row extending parallel to the first row, wherein the third row is between the first row and the second row; a first recess extending inward from one end of the conductive member, wherein the first recess is between the first row and the third row; and a second recess extending inward from one end of the conductive member, wherein the second recess is between the second row and the third row. Claim 11 A conductive member according to claim 10, wherein the first plurality of openings are configured to be connected to the first plurality of passive electric elements, the second plurality of openings are configured to be connected to the second plurality of passive electric elements, and the third plurality of openings are configured to be connected to the plurality of conductive elements. Claim 12 In claim 11, the first plurality of passive electric elements and the second plurality of passive electric elements are charge storage devices, and the plurality of conductive elements are conductive members configured to direct the current into the discharge chamber. Claim 13 A conductive member according to claim 10, further comprising: a third recess extending inward from the remaining end of the conductive member—the third recess is between the first row and the third row—; and a fourth recess extending inward from the remaining end of the conductive member—the fourth recess is between the second row and the third row. Claim 14 A conductive member according to claim 10, wherein the first recess separates the outermost opening among the first plurality of openings from the outermost opening among the third plurality of openings. Claim 15 A conductive member according to claim 10, wherein two of the first plurality of openings extending inward from the first end and two of the third plurality of openings extending inward from the first end are separated by the first recess, and two of the second plurality of openings extending inward from the first end and two of the third plurality of openings extending inward from the first end are separated by the second recess. Claim 16 In claim 10, a conductive member further comprising a dielectric portion filled in the first and second recesses, wherein the dielectric portion has a U-shape. Claim 17 A conductive member according to claim 10, wherein the dimensions of the first recess are in the range of 3 cm to 20 cm. Claim 18 A method for equalizing current density within a light source device, comprising the step of forming at least one recess on each end of a conductive member located outside a discharge chamber, wherein the conductive member is configured to conduct current from a plurality of charge storage devices. Claim 19 A method for homogenizing current density within a light source device, wherein, in paragraph 18, the at least one recess on each end of the conductive member extends inward along the longitudinal direction of the conductive member. Claim 20 A method for homogenizing current density within a light source device, further comprising the step of increasing the dimensions of at least one recess to increase the current from each of the plurality of charge storage devices to each of the plurality of feedthrough elements.