Configurable resonant charging supply and method for a pulsed power laser platform

Abstract

A resonant charging supply for a pulsed power supply system for a discharge laser, the configurable resonant charging circuit having one or more of a variable inductor, a programmable energy calculation circuit, a programmable voltage scaling and control circuit, a programmable current scaling and control circuit, and a programmable repetition rate limiter so that the resonant charging circuit is configurable to be able to work with any one of a number of laser platforms having differing operational parameters.

Description

CONFIGURABLE RESONANT CHARGING SUPPLYAND METHOD FOR A PULSED POWER LASER PLATFORMCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Application No. 63 / 555,478, filed February 20, 2024, titled CONFIGURABLE RESONANT CHARGING SUPPLY AND METHOD FOR A PULSED POWER LASER PLATFORM, which is incorporated herein by reference in its entirety.FIELD

[0002] The present disclosure relates to systems for and methods of generating electrical pulses used in lasers to serve, for example, as illumination sources in a lithographic apparatus or an inspection apparatus.BACKGROUND

[0003] A lithographic apparatus applies a desired pattern onto a substrate such as a wafer of semiconductor material, usually onto a target portion of the substrate. A patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a pattern to be formed on an individual layer of the wafer. Transfer of the pattern is typically accomplished by imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain adjacent target portions that are successively patterned. Features patterned on the photoresist may include exposure patterns that serve as a key basis for, e.g., etching, deposition, implantation, metallization, and / or other semiconductor fabrication steps. These steps can serve as important portions of a process to form semiconductor devices, integrated circuits, microelectronic devices, or other electronic devices.

[0004] Lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0005] The light source used to illuminate the pattern and project it onto the substrate can be of any one of a number of configurations. Deep ultraviolet excimer lasers commonly used in lithography systems include the krypton fluoride (KrF) laser, which delivers light at a wavelength of 248 nm and the argon fluoride (ArF) laser, which delivers light at a wavelength of 193 nm.

[0006] Such lasers use pulses of electrical energy to create electrical discharges between the electrodes of a discharge chamber. The systems for supplying the electrical pulses typically include a resonantcharging supply (RCS) or equivalently a resonant charger (RC). The RCS must provide regulated and repeatable energy for each laser pulse. The energy can be constant pulse -to-pulse or vary pulse-to-pulse based on the user’s needs.

[0007] The operational characteristics of the RCS vary according to the configuration of the laser platform for which the RCS supplies pulses. For example, the laser platform may be one in which the pulses are required at a rate of up to 4000 pulses per second (pps). This means that the RCS must be able to recharge within a certain recharge time ti. Other laser platforms may require a larger number of pulses per second, e.g., at a rate of up to 6000 pps. Such a platform thus requires an RCS with a shorter recharge time t2 < ti.

[0008] Also, a laser platform may have only a single chamber or a laser platform may have multiple chambers. A laser platform may have, for example, two chambers such as in a master oscillator / power oscillator (MOPO), master oscillator / amplifier (MOP A) or master oscillator / power ring amplifier (MOPRA) configuration. In such two chamber platforms the RCS is called upon to charge two independent capacitive loads in parallel from two separate pulsed power systems to drive two separate chambers. This also imposes limits on the maximum amount of charge time.

[0009] There are other aspects of the RCS which are set up to work with a specific type of laser platform. For example, the RCS might typically include an energy calculation circuit. The energy calculation circuit is an analog circuit or an analog / digital circuit that is provided to regulate the amount of energy that is stored in the charging inductor and the charging capacitor in the RCS and the load capacitor in one or more associated commutators. The energy calculation circuit is typically configured so that it is appropriate for use in a particular laser platform. For example, resistance values, capacitance values, and inductance values may be pre-selected in a set of RCS units so that they are suitable for use or optimized for use with a specific model of laser.

[0010] Typically the need to meet the particular requirements of each of a variety of laser platforms is satisfied by having a matching variety of pulsed power systems available in inventory, one for each type of laser platform, each with an RCS specifically designed and calibrated to interface with that type of laser platform. As a consequence, a range of pulsed power systems must be manufactured and kept in stock. Maintaining several different RCS configurations stresses both the pulsed power supply chain and the management of field inventory.

[0011] It is in this context that the need for the subject matter disclosed herein arises.SUMMARY

[0012] The following presents a succinct summary of one or more embodiments in order to provide a basic understanding of the embodiments. This summary is not an extensive overview of all contemplated embodiments and is not intended to identify as key or critical any elements of the embodiments nor delineate the scope of any or all embodiments. Its sole purpose is to present someconcepts of one or more embodiments in a streamlined form as a prelude to the more detailed description that is presented later.

[0013] According to an aspect of an embodiment there is disclosed a resonant charging supply for a pulse power circuit for supplying pulses to a laser discharge chamber, the resonant charging circuit comprising an energy storage capacitor, a switch, a charging inductor arranged to conduct a current from the energy storage capacitor when the switch is closed, the charging inductor having a variable inductance, and a load capacitor arranged to be charged by the current conducted by the charging inductor.

[0014] The charging inductor may comprise a cylindrical core and a coil surrounding at least an axial portion of the core, wherein the core and the coil are movable with respect to one another to alter a degree of axial overlap of the coil with the core.

[0015] The charging inductor may comprise a core having a first segment and a second segment, the second segment being moveable with respect to the first segment, and a coil surrounding at least a portion of the first segment, wherein the first segment and the second segment are separated by at least one gap, a width of the at least one gap being alterable by moving the second segment with respect to the first segment.

[0016] The charging inductor may comprise a core having a first arm, a second arm spaced apart from the first arm to define a gap therebetween, and a joining portion joining the first arm and the second arm, a coil surrounding at least a portion of the joining portion, and a plurality of spaced-apart core elements arranged in the gap in a series between the first arm and the second arm, and further comprise a plurality of switches arranged to selectably electrically interconnect the first arm, the second arm, and respective ones of the core elements.

[0017] The charging inductor may comprise a core, a main coil positioned around a first portion of the core, a control coil positioned around a second portion of the core different from the first portion, and a current source arranged to cause a current to flow through the control coil when the current source is electrically connected to the current source.

[0018] The resonant charging supply may generate a charging pulse in response to a charge signal being applied to the switch and the resonant charging supply further may comprise a current measuring device for generating a measured current signal indicative of an amount of current flowing through the charging inductor, a voltage measuring device for generating a measured voltage signal indicative of an amount of voltage drop across the charging capacitor, a deque circuit arranged to inhibit an increase in a voltage of the charging pulse in response to a deque signal, and a programmable energy calculation unit arranged to receive the measured current signal and the measured voltage signal and for generating the charge signal and the deque signal based at least in part on the measured current signal and the measured voltage signal.

[0019] The programmable energy calculation unit may comprise a processor and a memory.

[0020] The programmable energy calculation unit may comprise a programmable logic array.

[0021] The resonant charging supply may further comprise a programmable voltage control circuit for controlling an amount of voltage generated by the resonant charging supply.

[0022] The resonant charging supply may further comprise a programmable current control circuit for controlling an amount of current generated by the resonant charging supply.

[0023] The resonant charging supply may further comprise a programmable repetition rate control circuit for limiting a repetition rate at which the resonant charging supply may operate.

[0024] According to another aspect of an embodiment there is disclosed a laser system comprising a laser control system, a laser discharge chamber, and a pulse power circuit arranged to supply pulses to the laser discharge chamber, the pulse power circuit including a resonant charging supply. The resonant charging supply may comprise an energy storage capacitor, a switch, and a charging inductor arranged to conduct a current from the energy storage capacitor when the switch is closed. The charging inductor may have a variable inductance. The resonant charging supply may additionally comprise a load capacitor arranged to be charged by the current conducted by the charging inductor, a programmable voltage control circuit for controlling an amount of voltage generated by the resonant charging supply, a programmable current control circuit for controlling an amount of current generated by the resonant charging supply, and a programmable repetition rate control circuit for controlling a repetition rate at which the resonant charging supply may operate. The resonant charging supply may also comprise a communications bus connected to the laser control system and to the programmable voltage control circuit, the programmable current control circuit, and the programmable repetition rate control circuit to allow communication between the laser control system and the programmable voltage control circuit, the programmable current control circuit, and the programmable repetition rate control circuit.

[0025] According to another aspect of an embodiment there is disclosed a resonant charging supply for a pulse power circuit for supplying pulses to a laser discharge chamber, the resonant charging supply comprising an energy storage capacitor, a switch, a charging inductor arranged to conduct a current from the energy storage capacitor when the switch is closed, the charging inductor having a variable inductance, and a load capacitor arranged to be charged by the current conducted by the charging inductor. The resonant charging supply may also comprise a current measuring device for generating a measured current signal indicative of an amount of current flowing through the charging inductor, a voltage measuring device for generating a measured voltage signal indicative of an amount of voltage drop across the load capacitor, a deque circuit arranged to inhibit an increase in a voltage of the charging pulse in response to a deque signal, and a programmable energy calculation unit arranged to receive the measured current signal and the measured voltage signal and for generating the charge signal and the deque signal based at least in part on the measured current signal and the measured voltage signal.

[0026] The programmable energy calculation unit may comprise a processor and a memory.

[0027] The programmable energy calculation unit may comprise a programmable logic array.

[0028] The resonant charging supply may further comprise a programmable voltage control circuit for controlling an amount of voltage generated by the resonant charging supply.

[0029] The resonant charging supply may further comprise a programmable current control circuit for controlling an amount of current generated by the resonant charging supply.

[0030] The resonant charging supply may further comprise a programmable repetition rate control circuit for controlling a repetition rate at which the resonant charging supply may operate.

[0031] According to another aspect of an embodiment there is disclosed a method of configuring a configurable resonant charging supply comprising providing an unconfigured configurable resonant charging supply, obtaining one or more operating parameters of a laser platform with which it is desired to use the unconfigured configurable resonant charging supply, configuring the unconfigured resonant charging supply in accordance with the operating parameters to obtain a configured resonant charging supply, and integrating the configured resonant charging supply with the laser platform.

[0032] Integrating the configured resonant charging supply with the laser platform may comprise installing the configured resonant charging supply into the laser platform with the obtaining the one or more operating parameters of the laser platform being performed after the installing.

[0033] Obtaining the one or more operating parameters of the laser platform may be performed in response to the installing.

[0034] The obtaining one or more operating parameters of the laser platform may include obtaining one or more of operating voltage, operating current, charging inductor inductance, maximum operating voltage, maximum operating current, and maximum permissible repetition rate of the laser platform.

[0035] Configuring the unconfigured resonant charging supply may include one or more of adjusting the inductance of a variable inductor in the resonant charging supply, programming an energy control circuit in the resonant charging supply, programming a limiting voltage in the resonant charging supply, programming a limiting current in the resonant charging supply, programming a scaling voltage in the resonant charging supply, programming a scaling current in the resonant charging supply, and programming a maximum repetition rate for operation of the resonant charging supply.

[0036] According to another aspect of an embodiment there is disclosed a process of making a semiconductor device comprising configuring a resonant charging supply of a deep ultraviolet (DUV) light source and subsequently exposing a photoresist on a semiconductor substrate with light from the DUV light source, wherein the configuring may comprise providing an unconfigured configurable resonant charging supply, obtaining one or more operating parameters of a laser platform with which it is desired to use the unconfigured configurable resonant charging supply, configuring the unconfigured resonant charging supply in accordance with the operating parameters to obtain a configured resonant charging supply, and integrating the configured resonant charging supply with the laser platform.

[0037] Further features and advantages of the disclosed subject matter, as well as the structure and operation of various embodiments of the disclosed subject matter, are described in detail below withreference to the accompanying drawings. It is noted that the disclosed subject matter is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein.BRIEF DESCRIPTION OF THE DRAWING

[0038] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate the disclosed subject matter and, together with the description, further serve to explain the principles of the disclosed subject matter and to enable a person skilled in the relevant art(s) to make and use the disclosed subject matter. The drawings are not to scale unless otherwise indicated.

[0039] FIG. 1 is a functional block diagram of a pulse power circuit according to an aspect of an embodiment.

[0040] FIG. 2 is a simplified circuit diagram for a portion of the pulse power circuit.

[0041] FIG. 3 is a simplified circuit diagram for a portion of the pulse power circuit according to an aspect of an embodiment.

[0042] FIG. 4A is a perspective view of a variable inductor such as might be used in the circuit of FIG.3 according to an aspect of an embodiment.

[0043] FIG. 4B is a perspective view of the variable inductor of FIG. 4A with an inductance set to a different value according to an aspect of an embodiment.

[0044] FIG. 4C is a partially perspective and partially schematic view of a variable inductor such as might be used in the circuit of FIG. 3 according to an aspect of an embodiment.

[0045] FIG. 5 A is a perspective view of conventional inductor with a fixed air gap.

[0046] FIG. 5B is a perspective view of variable inductor such as might be used in the circuit of FIG.3 according to an aspect of an embodiment.

[0047] FIG. 6 is a perspective view of variable inductor such as might be used in the circuit of FIG. 3 according to an aspect of an embodiment.

[0048] FIG. 7 is a perspective view of variable inductor such as might be used in the circuit of FIG. 3 according to an aspect of an embodiment.

[0049] FIG. 8 is a functional block diagram of a digital energy calculation circuit such as might be used in the circuit of FIG. 3 according to an aspect of an embodiment.

[0050] FIG. 9 is a functional block diagram of a voltage control circuit such as might be used in the circuit of FIG. 3 according to an aspect of an embodiment.

[0051] FIG. 10 is a functional block diagram of a current control circuit such as might be used in the circuit of FIG. 3 according to an aspect of an embodiment.

[0052] FIG. 11 is a functional block diagram of a repetition rate sensor and control circuit such as might be used in the circuit of FIG. 3 according to an aspect of an embodiment.

[0053] FIG. 12 is a flow chart of a method of configuring a configurable resonant charging supply according to an aspect of an embodiment.

[0054] The features and advantages of the disclosed subject matter 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.DETAILED DESCRIPTION

[0055] Various embodiments are now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to promote a thorough understanding of one or more embodiments. It may be evident in some or all instances, however, that any embodiment can be practiced without adopting the specific design details associated with it below. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate description of one or more embodiments.

[0056] FIG. 1 is a functional block diagram of a pulsed power system that includes a high voltage power supply 30, an RCS 40, a commutator 50, a compression head module 60, and a laser chamber 70. These components other than the laser chamber 70 make up a solid state pulsed power module (S SPPM) . High voltage power supply 30 converts normal three phase plant power to a high DC voltage . The RCS 40 generates pulses to charge capacitor banks in the commutator 50 to generate shorter pulses having an increased voltage. The compression head 60 further temporally compresses the pulses from the commutator 50 with a corresponding increase in current to produce pulses with the desired discharge voltage and applies the pulses across the electrodes in the laser discharge chamber 70. Additional details of arrangement and operation of such a laser system can be found, for example, in U.S. Patent No. 7,079,564, titled “Control System for a Two Chamber Gas Discharge Laser” issued July 18, 2006, and U.S. Patent Application Publication No. 2009 / 0238225, titled “6K Pulse Repetition Rate and Above Gas Discharge Laser System Solid State Pulse Power System Improvements,” published September 24, 2009.

[0057] All patent applications, patents, and printed publications cited herein are incorporated herein by reference in their entireties, except for any definitions, subject matter disclaimers, or disavowals, and except to the extent that the incorporated material is inconsistent with the express disclosure herein, in which case the language in this disclosure controls.

[0058] FIG. 2 is a simplified circuit diagram for a portion of a pulsed power system including the RCS 40 (between lines A and B) and part of a commutator 50 (right of line B) according to an aspect of an embodiment. FIG. 2 shows only the salient components of the circuits for the purposes of explainingtheir operation in the context of this disclosure. It will be understood that in practice there will be additional components such as resistors and additional diodes and capacitors.

[0059] An energy calculation circuit 100 initiates a pulse by applying a trigger or charge signal to a switch 110 which may be implemented as an insulated-gate bipolar transistor (IGBT) as shown in the example of FIG. 2. The charge signal closes the switch 110 which permits charge to flow from a energy storage capacitor 120 through a charging inductor 140. A freewheel diode 130 is used to cap the magnitude of the charging voltage. The current flows through the charging inductor 140 and charges a load capacitor 150 which is part of the commutator 50. The resulting pulse then propagates to further modules to result in the discharge pulse for the discharge chamber.

[0060] Also shown in FIG. 2 is a current measuring device, such as current sensor 145, arranged to sense the magnitude of the current through the charging inductor 140 and supply a signal I indicative of the sensed current to the energy calculation circuit 100. The current sensor 145 may be any suitable device or circuitry capable of measuring the magnitude of a current and generating a signal indicative of the sensed magnitude such an ammeter. Also shown in FIG. 2 is a voltage sensor 155 arranged to sense the magnitude of the voltage across the load capacitor 150 and supply a signal V indicative of the sensed voltage to the energy calculation circuit 100. The voltage sensor 155 may be any suitable device or circuitry capable of measuring the magnitude of a voltage and generating a signal indicative of the sensed magnitude such an voltmeter.

[0061] Thus, prior to a command for a laser pulse the voltage on the energy storage capacitor 120 is charged to a desired voltage. Upon a command for a laser pulse the energy calculation circuit 100 provides the charge signal to the switch 110 which closes the switch 110. At this time current flows from energy storage capacitor 120 to the load capacitor 150 through the charging inductor 140. The energy calculation circuit 100 evaluates the voltage on the load capacitor 150 and the current flowing in the charging inductor 140 from feedback signals I and V. The switch 110 will be caused to open when energy stored in charging inductor 140 and the load capacitor 150 are sufficient to generate the commanded voltage on the load capacitor 150.

[0062] FIG. 2 also shows a deque loop 170 implemented in the example shown as a diode 172 and a deque switch 174. The deque or De-Quing loop 170 improves the regulation of the circuit by allowing the energy calculation circuit 100 to bypass the charging inductor 140 during the resonant charging process effectively by spoiling the Q or quality factor of the resonant circuit. When the energy calculation circuit 100 determines that the voltage on the load capacitor 150 nears a target charging VT it applies a deque signal to the deque loop 170 thus closing the deque switch 174, stopping resonant charging when the voltage on the load capacitor 150 is at or slightly above or below the target value VT.

[0063] In the arrangement shown in FIG. 2, it is necessary to construct the RCS so that it is suitable for use with one particular type of discharge laser platform in terms of repetition rate, number ofchambers, electrical characteristics of chambers, and so on. In accordance with an aspect of an embodiment, a variable inductor is used as the charging inductor thus mitigating the need to have a dedicated type of RCS on hand for every possible configuration of laser discharge platform. Instead, a variable inductor in a configurable RCS can be adjusted to adapt the RCS to operate with any one of a variety of laser discharge platforms. For example, the variable inductor can be adjusted to an inductance value that is matched with or compatible with capacitance of downstream capacitors and other downstream circuit elements. For example, an inductance value may be matched with downstream components to ensure an overall same or similar LC charge time constant (RCS charging time).

[0064] An arrangement incorporating a variable inductor is shown in FIG. 3, which includes a charging inductor configured as a variable inductor 210. Because the charging inductor is variable its inductance can be set to be compatible with any one of a number of different possible discharge laser platforms. This obviates the need to manufacture and stock a range of pulsed power systems thus alleviating stress on the pulsed power supply chain and management of field inventory.

[0065] The inductance of the variable inductor 210 may be varied manually or under the control of a signal S applied to an actuator which is part of the variable inductor S. The variable inductor 210 can be implemented in any one of a number of ways. For example, the variable inductor 210 may be implemented as a coil wrapped around a core in which an amount of overlap between the coil and the core is variable. FIG. 4A shows a variable inductor 210 having a coil 220 wrapped around a core 230. The coil 220 may be made of a conductive material such as a metal. The core 230 may be made out of a magnetic material such as a ferrite. The relative positions of the coil 220 and the core 230 can be changed by moving the core 230 with respect to the coil 220 in the direction indicated by the arrow C. This results, for example, in a relative positioning such as that shown in FIG. 4B. By adjusting the relative positions of the coil 220 and the coil 230, different values may be obtained for the inductance of the variable inductor 210.

[0066] In other words in this embodiment the variable charging inductor comprises a cylindrical core and a coil surrounding at least an axial portion of the core, wherein the core and the coil are movable with respect to one another to alter a degree of axial overlap of the coil over the core and so the inductance. The relative positions of the coil 220 and the core 230 may be adjusted manually or by an actuator (not shown). This is true of all embodiments having relatively movable elements.

[0067] FIG 4C shows another possible arrangement for a variable inductor. In the arrangement shown in FIG. 4C, a variable inductor 250 is made up of a core 260 and coil 274, coil 276, and coil 278. Three coils are shown in the arrangement of FIG. 4C but one of ordinary skill in the art will appreciate that a different number of coils may be used. The coils are connected to a switch network 280 which selectively connects the coils to each other and to the leads 292 and 294 in response to a control signal E to change the net effective inductance of the variable inductor 250. For example, the switch network 280 may connect the coil 274 and the coil 276 together and connect the combined coils to the leads 292and 294 in response to a control signal E. As an alternative, the switch network 280 can connect all three coils together and to the leads 292 and 294 in response to a control signal E. As another alternative, the switch network 280 can connect only one of coil 274, coil 276, and 278 to the leads 292 and 294. The net effective inductance seen from the leads 292 and 294 will change depending on the number of coils the switch network 280 connects to leads 292 and 294 in response to the control signal E.

[0068] FIG. 4C shows an arrangement in which the coil 274, coil 276, and coil 278 have the same number of turns. It will be apparent to one of ordinary skill in the art, however, that the coils may respectively have a number of turns that are different from each other. This makes it possible to use selectable interconnection of some of the larger (more turns) coils for larger changes in inductance (coarse adjustment) and other, smaller (fewer turns) coils for smaller changes in inductance (fine adjustment).

[0069] FIG. 5 A shows a conventional gapped fixed value inductor 300 in which the inductance is determined in part by the width of a gap 330. The fixed value inductor 300 has a coil 310 wrapped around a portion of a core 320. The core 320 is generally G-shaped having the gap 330. The width of the gap 330 affects the magnitude of the inductance of the inductor 300. FIG. 5B shows a variable inductor 350 having a variable gap. In FIG. 5B, the variable inductor 350 has a coil 360 wrapped around a portion of a U-shaped first core segment 370. A second core segment 380 is arranged to be spaced away from the first core segment 370 by a gap 390 and a gap 395. The second core segment 380 can be moved with respect to the first core segment 370 by moving the second core segment 380 in the direction indicated by the arrow D. This varies the respective widths of the gap 390 and the gap 395. In this manner, the magnitude of the inductance of the variable inductor 350 is varied.

[0070] FIG. 5B shows a configuration in which the width of the gap 330 is changed in the direction of the arrow D, that is, up and down or in the y direction as oriented in the figure. It is also possible to vary the inductance by changing the amount of separation of the core segments in one or both of the other two directions, i.e., x and z, or by tilting or rotating the core segments with respect to each other, or some combination of these motions. The separation or misalignment will cause the inductance to vary.

[0071] In other words, in this embodiment the charging inductor includes a core having two or more segments. At least one of the segments is moveable with respect to another of the segments. The charging inductor also has a coil surrounding at least a portion of one or more of the segments. The segments are separated by at least one gap, the width of the gap being alterable by moving one of the segments with respect to another segment.

[0072] FIG. 6 shows another possible configuration for a variable inductor. In FIG. 6, a variable inductor 400 has a core having a first arm 410 and a second arm 412 joined together by a joining portion 415. The core arms can be joined together or integral with one another to form a single U-shaped segment. The core is thus generally U-shaped with the first arm 410 being a lower arm and the second arm 412 being an upper arm as oriented in the figure. A coil 420 is wrapped around a portion of thejoining portion 415. A series of spaced-apart core elements is arranged in the space between the arms of the U. Thus there is a first core element 430, a second core element 440, and a third core element 450. One of ordinary skill in the art will appreciate that any suitable number of core element may be used. The first core element 430 defines a gap 425 with the second core arm 412. Similarly, first core element 430 and second core element 440 define a gap 435. The second core segment element and the third core element 450 define a gap 445. Also, the third core element 450 and the first core arm define a gap 455.

[0073] The core elements are selectably interconnected with each other through a switch network 460 under the control of a control signal E to effectively short-circuit selected ones of the gaps. The effective width of the gap of the variable inductor 400, and therefore, the inductance of the variable inductor 400, will depend on the interconnection of segments with gaps that are shorted. The effective gap for the overall arrangement and thus the inductance can be controlled by selectably interconnecting the core elements and segments.

[0074] In other words in this embodiment the charging inductor comprises a core having a first arm, a second arm spaced apart from the first arm to define a gap therebetween, and a joining portion arranged to connect the first arm and the second arm. It also comprises a coil surrounding at least a portion of the joining portion, and a plurality of spaced-apart core elements arranged in the gap in a series between the first arm and the second arm. A plurality of switches is arranged to selectably electrically interconnect the first arm, the second arm, and respective ones of the core elements. “Selectably” herein means that the combination of electrical interconnections (and lack of interconnections) can be selected by inputs to a control module of the charging inductor.

[0075] FIG. 6 shows an arrangement in which the core element 430, core element 440, and core element 450 are approximately the same size. It will be apparent to one of ordinary skill in the art, however, that the cores may respectively have sizes that are different from each other. This makes it possible to use selectable interconnection of some of the cores for larger changes in inductance (coarse adjustment) and other cores for smaller changes in inductance (fine adjustment).

[0076] FIG. 7 shows another possible configuration for a variable inductor. In FIG. 7, a variable inductor 500 has a main coil 510 terminating in a pair of terminals 512, 514 and a core 520 having a shape generally referred to as having an E-shaped structure. There is also a control coil 530 wrapped around part of the core 520. A current source 540 causes a current to flow in the control coil 530 under the control of a signal F.

[0077] Current flowing through the coil 510 of the variable inductor 500 induces an AC flux circulating through a center arm of the core 520 and splits to the outer arms of the core 520. Applying a relatively small DC bias current to the control coil 530 produces a DC flux which circulates primarily through the outer closed path of the core. This DC flux can bias the operation of the magnetic material towards thenonlinear region on the B(H) curve, thus causing the inductance seen from the terminals to vary as a function of the DC bias current.

[0078] According to another aspect of an embodiment, the configurability of the RCS is further or alternatively enhanced by providing an energy calculation circuit that is more readily adaptable to multiple types of laser discharge platforms. This is effected in an embodiment by providing a programmable energy calculation circuit that can be configured digitally rather than an energy calculation circuit that is primarily analog and adjusted only by adjusting one or more potentiometers.

[0079] In FIG. 3 such a programmable energy calculation circuit is represented as energy calculation circuit 600. FIG. 8 is a functional block diagram of a possible arrangement for the energy calculation circuit 600. As shown, the energy calculation circuit 600 receives the signal I from the current sensor 145 indicative of the magnitude of the current going through the charging inductor 210 and the signalV from the voltage sensor 155 indicative of the voltage across the load capacitor 150. The signal I indicative of the current is converted by an analog to digital converter (ADC) 610. Similarly, the signalV indicative of the voltage is converted by an ADC 620. The digital signals representative of these magnitudes are placed on a bus 630. A charge determination circuit 640 receives the digital signals indicative of the voltage and current magnitudes and generates a charge signal based on whether the magnitudes of the current and voltage meet the programmed conditions for the generation of that signal. The charge determination circuit 640 may include an application specific integrated circuit (ASIC), field programmable gate array (FPGA), a processor with memory or any other programmable logic device which can generate the charge signal based on a programmed combination of the current and voltage. Similarly, a deque determination circuit 660 receives data indicative of the measured magnitudes of the current and voltage and generates a deque signal based on these signals. The deque determination circuit 660 also may include an application specific integrated circuit (ASIC), field programmable gate array (FPGA), a processor with memory or any other programmable logic device which can generate the deque signal based on a programmed combination of the current and voltage.

[0080] Also as shown in FIGs. 3 and 8 the bus 630 can communicate with the rest of the laser platform including a laser system controller 190 through a communications port 680. This communications port 680 can be used to alter the programming, e.g., firmware and / or lookup table values, of the charge determination circuit 640 and the deque determination circuit 660 and so that the combination of voltage and current that will result in generation of the charge signal can be adjusted as can the combination of voltage and current that will result in generation of the deque signal. The RCS components may, for example, communicate with the laser system controller 190 in the laser control platform through an existing communication protocol, such as Serial Peripheral Interface (SPI) protocol which is a synchronous communication protocol that transmits and receives data simultaneously, to acquire laser platform information to configure the internal circuits described herein.

[0081] The arrangement of FIG. 3 also includes a voltage control unit 700. Here and elsewhere in this specification the term “control” in this phrase refers to regulation of one or more aspects of the voltage, including limiting the voltage and scaling the voltage. FIG. 9 is a functional block diagram of a possible arrangement for the voltage control / scaling unit 700. As shown, voltage control / scaling unit 700 receives the signal V from the voltage sensor 155 indicative of the voltage across the load capacitor 150. The signal V indicative of the voltage is converted by an ADC 710. The digital signal representative of the magnitude of V is placed on a bus 720. A voltage comparison circuit 730 receives the digital signal indicative of the voltage and generates a signal GV based on the magnitude of the voltage. For example, the voltage comparison circuit 730 may determine whether the magnitude of the voltage exceeds a programmed threshold. In such an implementation the signal GV may be used to trip RCS safety interlocks if the voltage V exceeds the programmed threshold.

[0082] The voltage comparison circuit 730 may in addition or alternatively capture other parameters. For example, the voltage comparison circuit 730 can be used for voltage regulation by determining whether the voltage is within a set tolerance of the requested or commanded program voltage. In other words, the voltage comparison circuit 730 can determine whether the measured voltage is within, for example, 0.1% of the requested program voltage. In cases where the RCS is configured to generate dual outputs, the voltage comparison circuit 730 can determine whether the voltage difference between the dual outputs is within a certain tolerance, e.g., 0.1%. The voltage comparison circuit 730 can also be configured to determine whether the measured voltage falls below a certain threshold, or is absent (load fault), or that a voltage reversal has occurred.

[0083] The signal GV may also be used to scale the operating parameters used by the laser platform to accommodate any of various laser platforms which may use voltages of differing magnitudes. The voltage comparison circuit 730 may include an ASIC, an FPGA, a processor with memory or any other programmable logic device which can generate the signal G based on a programmed threshold voltage.

[0084] Also as shown in FIGs. 3 and 9 the bus 720 can communicate with the rest of the laser platform through a communications port 740. This communications port 740 can be used to alter the programming of the voltage comparison circuit 730 so that the voltage that will result in generation of the signal GV can be adjusted to accommodate various laser platforms which may use voltages and voltage thresholds of differing magnitudes.

[0085] The arrangement of FIG. 3 also includes a current control unit 800. Here and elsewhere in this specification the term “control” in this phrase refers to regulation of one or more aspects of the current, including limiting the current and scaling the current. FIG. 10 is a functional block diagram of a possible arrangement for the current control / scaling unit 800. As shown, current control / scaling unit 800 receives the signal I from the current sensor 145 indicative of the magnitude of the current flowing through the charging inductor 140. The signal I indicative of the magnitude of the current is converted by an ADC 810. The digital signal representative of the magnitude of I is placed on a bus 820. A current comparisoncircuit 830 receives the digital signal indicative of the magnitude of the current and generates a signal GI based on whether the magnitude of the current exceeds a programmed threshold.

[0086] The current comparison circuit 830 may in addition or alternatively capture other current parameters. For example, the current comparison circuit 830 can be used for current regulation by determining whether the magnitude of the current is within a set tolerance of the requested or commanded current. In other words, the current comparison circuit 830 can determine whether the measured current is within, for example, 0.1% of the requested program current. In cases where the RCS is configured to generate dual outputs, the current comparison circuit 830 can determine whether the difference in the respective magnitudes of the currents between the dual outputs is within a certain tolerance, e.g., 0.1%. The current comparison circuit 830 can also be configured to determine whether the measured current falls below a certain threshold, or is absent (load fault), or whether a current reversal has occurred.

[0087] The signal GI may be used to scale the operating parameters used by the laser platform to accommodate any of various laser platforms that are designed to use currents of differing magnitudes. The current comparison circuit 830 may include an ASIC, an FPGA, a processor with memory or any other programmable logic device which can generate the signal GI based on a programmed threshold current.

[0088] Also as shown in FIGs . 3 and 10 the bus 820 can communicate with the rest of the laser platform through a communications port 840. This communications port 840 can be used to alter the programming of the current comparison circuit 830 so that the current that will result in generation of the signal GI can be adjusted to accommodate any of various laser platforms designed to use currents of differing magnitudes.

[0089] The arrangement of FIG. 3 also includes a repetition rate (reprate) controller 900. FIG. 11 is a functional block diagram of a possible arrangement for the repetition rate controller 900. As shown, repetition rate controller 900 receives the charge, i.e., trigger signal indicative of the onset of the generation of a pulse. A repetition rate sensor 910 determines a repetition rate from the time between successive pulses and generates a signal indicative of the determined repetition rate on a bus 920. A repetition rate comparison unit 930 compares the measured repetition rate and generates a signal H based on whether the magnitude of the measured repetition rate exceeds a programmed threshold. The signal H may be used, for example, to disable the laser platform if the measured repetition rate exceeds the programmed threshold for that platform. The repetition rate comparison unit 930 may include an ASIC, an FPGA, a processor with memory or any other programmable logic device which can generate the signal H based on comparison with a programmed threshold repetition rate.

[0090] Also as shown in FIGs. 3 and 11 the bus 920 can communicate with the rest of the laser platform through a communications port 940. This communications port 940 can be used to alter the programming of the repetition rate comparison unit 930 so that the repetition rate that will result ingeneration of the signal H can be adjusted to accommodate any of various laser platforms which may use different repetition rates.

[0091] Thus, in accordance with an aspect of an embodiment, a programmable RCS may include a programmable RCS charging time through provision one or more of a variable inductor, a programmable voltage control circuit, a programmable current control circuit, and a programmable repetition rate circuit.

[0092] The programmable energy calculator is designed to ensure the programmable RCS can regulate energy to account for variances in the load capacitance, the charging inductance, and laser platform operating voltage range. The programmable current control circuit can ensure that the measured charging current is in same or similar amplitude range for any of various laser platforms. The programmable voltage control circuit can ensure that RCS works as intended without, for example, tripping RCS safety interlocks. The programmable repetition rate limit circuit can ensure that the measured repetition rate does not exceed design limits for a given laser platform.

[0093] FIG. 12 is a flow chart of a method of configuring an RCS in accordance with an aspect of an embodiment. In a step S10 an unconfigured configurable RCS is provided. In a step S20 the operating parameters of a laser platform with which it is desired to use the RCS are obtained. These operating parameters may include, but are not limited to, operating voltage, operating current, inductance of the charging inductor, charging capacitance, maximum operating voltages and currents, and maximum permissible repetition rate of the laser platform. In a step S30 the RCS is programmed or configured in accordance with the operating parameters obtained in step S20. The step S30 may include, but is not limited to, adjusting the inductance of a variable inductor in the RCS, programming an energy control circuit in the RCS, programming and scaling voltages and currents in the RCS, and establishing a maximum repetition rate for operation of the RCS. The RCS is then integrated with, e.g., installed in, the laser platform in a step S40. This may occur during the original manufacture of the laser platform or may occur in the field as part of a subsequent maintenance operation.

[0094] The step S30 could alternatively be performed after installation of the RCS module in the laser platform and connection to the control system bus. This could prevent field personnel or manufacturing personnel from loading the wrong parameters.

[0095] For example, an RCS module may be configured with a “plug and play” capability that provides automated detection and configuration. The RCS module may be configured with a sensing module and a configuration module. The sensing module can be configured to detect a type of laser platform into which the RCS module has been installed or inserted. Based on the detection, the sensing module can communicate with the configuration module so that the configuration module receives, looks up, or otherwise obtains relevant operating parameters of the laser platform (e.g., S20). Based on that those operating parameters, the configuration module can configure the RCS module (e.g., S30) for operation with the laser platform into which the RCS module has been installed or inserted.

[0096] Some of the above description is in terms of functional block diagrams with some functions allocated to some blocks and other functions allocated to other blocks. It will be understood that the division between blocks and the allocations are arbitrary and that different divisions and allocations are possible so long as the overall functions are carried out as described above.

[0097] The above description includes examples of multiple embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for each of these embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of elements of the various embodiments are possible based on the disclosure. Accordingly, the described embodiments are intended to be representative of and encompass all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims.

[0098] Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is construed when employed as a transitional word in a claim. Also, although elements of the described aspects and / or embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. Additionally, all or a portion of any aspect and / or embodiment may be utilized with all or a portion of any other aspect and / or embodiment, unless stated otherwise.

[0099] Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract, and drawings) may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0100] Furthermore, certain features that are described in this disclosure in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a subcombination or variation of a subcombination.

[0101] Moreover, while operations may be depicted in the drawings or described in the specification in a particular order, such operations need not be performed in the particular order shown or in sequential order, or that all operations be performed, to achieve desirable results. Other operationsthat are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated and / or disclosed may differ from those shown in the figures. Depending on the embodiment, certain of the steps described above may be removed, others may be added.

[0102] Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products.

[0103] For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

[0104] Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and / or steps. Thus, such conditional language is not generally intended to imply that features, elements, and / or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and / or steps are included or are to be performed in any particular embodiment.

[0105] Conjunctive language such as the phrase “at least one of X, Y, and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.

[0106] Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5 % of, within less than 1% of, within less than 0.1 % of, and within less than 0.01 % of the stated amount. As another example, in certain embodiments,the terms “generally parallel” and “substantially parallel” refer to a value, amount, or characteristic that departs from exactly parallel by less than or equal to 15 degrees, 10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree.

[0107] The scope of the present disclosure is not intended to be limited by the specific disclosures of preferred embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive.

[0108] The implementations can be further described using the following clauses.1. A resonant charging supply for a pulse power circuit for supplying pulses to a laser discharge chamber, the resonant charging circuit comprising: an energy storage capacitor; a switch; a charging inductor arranged to conduct a current from the energy storage capacitor when the switch is closed, the charging inductor having a variable inductance; and a load capacitor arranged to be charged by the current conducted by the charging inductor.2. The resonant charging supply of clause 1, wherein the charging inductor comprises a cylindrical core and a coil surrounding at least an axial portion of the core, wherein the core and the coil are movable with respect to one another to alter a degree of axial overlap of the coil with the cylindrical core.3. The resonant charging supply of clause 1, wherein the charging inductor comprises a core having a first segment and a second segment, the second segment being moveable with respect to the first segment, and a coil surrounding at least a portion of the first segment, wherein the first segment and the second segment are separated by at least one gap, a width of the at least one gap being alterable by moving the second segment with respect to the first segment.4. The resonant charging supply of clause 1, wherein the charging inductor comprises a core having a first arm, a second arm spaced apart from the first arm to define a gap therebetween, and a joining portion joining the first arm and the second arm, a coil surrounding at least a portion of the joining portion, a plurality of spaced-apart core elements arranged in the gap in a series between the first arm and the second arm, and a plurality of switches arranged to selectably electrically interconnect the first arm, the second arm, and respective ones of the core elements.5. The resonant charging supply of clause 1, wherein the charging inductor comprises a core,a main coil positioned around a first portion of the core, a control coil positioned around a second portion of the core different from the first portion, and a current source arranged to cause a current to flow through the control coil when the current source is electrically connected to the current source.6. The resonant charging supply of clause 1, wherein the resonant charging supply generates a charging pulse in response to a charge signal being applied to the switch and wherein the resonant charging supply further comprises a current measuring device for generating a measured current signal indicative of an amount of current flowing through the charging inductor, a voltage measuring device for generating a measured voltage signal indicative of an amount of voltage drop across the charging capacitor, a deque circuit arranged to inhibit an increase in a voltage of the charging pulse in response to a deque signal, and a programmable energy calculation unit arranged to receive the measured current signal and the measured voltage signal and for generating the charge signal and the deque signal based at least in part on the measured current signal and the measured voltage signal.7. The resonant charging supply of clause 6, wherein the programmable energy calculation unit comprises a processor and a memory.8. The resonant charging supply of clause 6, wherein the programmable energy calculation unit comprises a programmable logic array.9. The resonant charging supply of clause 6, further comprising a programmable voltage control circuit for controlling an amount of voltage generated by the resonant charging supply.10. The resonant charging supply of clause 6, further comprising a programmable current control circuit for controlling an amount of current generated by the resonant charging supply.11. The resonant charging supply of clause 6, further comprising a programmable repetition rate control circuit for limiting a repetition rate at which the resonant charging supply may operate.12. A laser system comprising: a laser control system; a laser discharge chamber; and a pulse power circuit arranged to supply pulses to the laser discharge chamber, the pulse power circuit including a resonant charging supply, the resonant charging supply comprising an energy storage capacitor, a switch, a charging inductor arranged to conduct a current from the energy storage capacitor when the switch is closed, the charging inductor having a variable inductance, a load capacitor arranged to be charged by the current conducted by the charging inductor,a programmable voltage control circuit for controlling an amount of voltage generated by the resonant charging supply, a programmable current control circuit for controlling an amount of current generated by the resonant charging supply, a programmable repetition rate control circuit for controlling a repetition rate at which the resonant charging supply may operate; and a communications bus connected to the laser control system and to the programmable voltage control circuit, the programmable current control circuit, and the programmable repetition rate control circuit to allow communication between the laser control system and the programmable voltage control circuit, the programmable current control circuit, and the programmable repetition rate control circuit.13. A resonant charging supply for a pulse power circuit for supplying pulses to a laser discharge chamber, the resonant charging supply comprising: an energy storage capacitor; a switch; a charging inductor arranged to conduct a current from the energy storage capacitor when the switch is closed, the charging inductor having a variable inductance; a load capacitor arranged to be charged by the current conducted by the charging inductor; a current measuring device for generating a measured current signal indicative of an amount of current flowing through the charging inductor; a voltage measuring device for generating a measured voltage signal indicative of an amount of voltage drop across the load capacitor; a deque circuit arranged to inhibit an increase in a voltage of the charging pulse in response to a deque signal; and a programmable energy calculation unit arranged to receive the measured current signal and the measured voltage signal and to generate the charge signal and the deque signal based at least in part on the measured current signal and the measured voltage signal.14. The resonant charging supply of clause 13, wherein the programmable energy calculation unit comprises a processor and a memory.15. The resonant charging supply of clause 13, wherein the programmable energy calculation unit comprises a programmable logic array.16. The resonant charging supply of clause 13, further comprising a programmable voltage control circuit for controlling an amount of voltage generated by the resonant charging supply.17. The resonant charging supply of clause 13, further comprising a programmable current control circuit for controlling an amount of current generated by the resonant charging supply.18. The resonant charging supply of clause 13, further comprising a programmable repetition rate control circuit for controlling a repetition rate at which the resonant charging supply may operate.19. A method of configuring a configurable resonant charging supply comprising:providing an unconfigured configurable resonant charging supply; obtaining one or more operating parameters of a laser platform with which it is desired to use the unconfigured configurable resonant charging supply; configuring the unconfigured resonant charging supply in accordance with the operating parameters to obtain a configured resonant charging supply; and integrating the configured resonant charging supply with the laser platform.20. The method of clause 19, wherein: integrating the configured resonant charging supply with the laser platform comprises installing configured resonant charging supply into the laser platform; and obtaining the one or more operating parameters of the laser platform is performed after installing the configured resonant charging supply with the laser platform.21. The method of clause 20, wherein: obtaining the one or more operating parameters of the laser platform is performed in response to installing the configured resonant charging supply with the laser platform.22. The method of clause 19, wherein the obtaining one or more operating parameters of the laser platform includes obtaining one or more of operating voltage, operating current, charging inductor inductance, maximum operating voltage, maximum operating current, and maximum permissible repetition rate of the laser platform.23. The method of clause 19, wherein configuring the unconfigured resonant charging supply includes one or more of adjusting the inductance of a variable inductor in the resonant charging supply, programming an energy control circuit in the resonant charging supply, programming a limiting voltage in the resonant charging supply, programming a limiting current in the resonant charging supply, programming a scaling voltage in the resonant charging supply, programming a scaling current in the resonant charging supply, and programming a maximum repetition rate for operation of the resonant charging supply.24. A process of making a semiconductor device comprising configuring a resonant charging supply of a deep ultraviolet (DUV) light source and subsequently exposing a photoresist on a semiconductor substrate with light from the DUV light source, wherein the configuring comprises providing an unconfigured resonant charging supply; obtaining one or more operating parameters of a laser platform with which it is desired to use the unconfigured resonant charging supply; configuring the unconfigured resonant charging supply in accordance with the operating parameters to obtain a configured resonant charging supply; and integrating the configured resonant charging supply with the laser platform

[0109] The above-described implementations and other implementations are within the scope of the following claims.

Claims

CLAIMS1. A resonant charging supply for a pulse power circuit for supplying pulses to a laser discharge chamber, the resonant charging circuit comprising: an energy storage capacitor; a switch; a charging inductor arranged to conduct a current from the energy storage capacitor, the charging inductor having a variable inductance; and a load capacitor arranged to be charged by the current conducted by the charging inductor.

2. The resonant charging supply of claim 1, wherein the charging inductor comprises a cylindrical core, and a coil surrounding at least an axial portion of the core, wherein the core and the coil are movable with respect to one another to alter a degree of axial overlap of the coil with the cylindrical core.

3. The resonant charging supply of claim 1, wherein the charging inductor comprises a core having a first segment and a second segment, the second segment being moveable with respect to the first segment, and a coil surrounding at least a portion of the first segment, wherein the first segment and the second segment are separated by at least one gap, a width of the at least one gap being alterable by moving the second segment with respect to the first segment.

4. The resonant charging supply of claim 1, wherein the charging inductor comprises a core having a first arm, a second arm spaced apart from the first arm to define a gap therebetween, and a joining portion joining the first arm and the second arm, a coil surrounding at least a portion of the joining portion, a plurality of spaced-apart core elements arranged in the gap in a series between the first arm and the second arm, and a plurality of switches arranged to selectably electrically interconnect the first arm, the second arm, and respective ones of the core elements.

5. The resonant charging supply of claim 1, wherein the charging inductor comprises a core, a main coil positioned around a first portion of the core, a control coil positioned around a second portion of the core different from the first portion, and a current source arranged to cause a current to flow through the control coil.

6. The resonant charging supply of claim 1, wherein the resonant charging supply generates a charging pulse in response to a charge signal being applied to the switch and wherein the resonant charging supply further comprises a current measuring device for generating a measured current signal indicative of an amount of current flowing through the charging inductor, a voltage measuring device for generating a measured voltage signal indicative of an amount of voltage drop across the charging capacitor, a deque circuit arranged to inhibit an increase in a voltage of the charging pulse in response to a deque signal, and a programmable energy calculation unit arranged to receive the measured current signal and the measured voltage signal and for generating the charge signal and the deque signal based at least in part on the measured current signal and the measured voltage signal.

7. The resonant charging supply of claim 6, further comprising a programmable voltage control circuit for controlling an amount of voltage generated by the resonant charging supply.

8. The resonant charging supply of claim 6, further comprising a programmable current control circuit for controlling an amount of current generated by the resonant charging supply.

9. The resonant charging supply of claim 6, further comprising a programmable repetition rate control circuit for limiting a repetition rate at which the resonant charging supply may operate.

10. A laser system comprising: a laser control system; a laser discharge chamber; and a pulse power circuit arranged to supply pulses to the laser discharge chamber, the pulse power circuit including a resonant charging supply, the resonant charging supply comprising an energy storage capacitor, a switch, a charging inductor arranged to conduct a current from the energy storage capacitor, the charging inductor having a variable inductance, a load capacitor arranged to be charged by the current conducted by the charging inductor, a programmable voltage control circuit for controlling an amount of voltage generated by the resonant charging supply, a programmable current control circuit for controlling an amount of current generated by the resonant charging supply,a programmable repetition rate control circuit for controlling a repetition rate at which the resonant charging supply may operate; and a communications bus connected to the laser control system and to the programmable voltage control circuit, the programmable current control circuit, and the programmable repetition rate control circuit to allow communication between the laser control system and the programmable voltage control circuit, the programmable current control circuit, and the programmable repetition rate control circuit.

11. A resonant charging supply for a pulse power circuit for supplying pulses to a laser discharge chamber, the resonant charging supply comprising: an energy storage capacitor; a switch; a charging inductor arranged to conduct a current from the energy storage capacitor when the switch is closed, the charging inductor having a variable inductance; a load capacitor arranged to be charged by the current conducted by the charging inductor; a current measuring device for generating a measured current signal indicative of an amount of current flowing through the charging inductor; a deque circuit arranged to inhibit an increase in a voltage of the charging pulse in response to a deque signal; and a programmable energy calculation unit arranged to receive the measured current signal and to generate the charge signal and the deque signal based at least in part on the measured current signal.

12. The resonant charging supply of claim 11, wherein the programmable energy calculation unit comprises a processor and a memory.

13. The resonant charging supply of claim 11, wherein the programmable energy calculation unit comprises a programmable logic array.

14. The resonant charging supply of claim 11, further comprising a programmable voltage control circuit for controlling an amount of voltage generated by the resonant charging supply.

15. A method of configuring a configurable resonant charging supply comprising: providing an unconfigured resonant charging supply; obtaining one or more operating parameters of a laser platform with which it is desired to use the unconfigured resonant charging supply; configuring the unconfigured resonant charging supply in accordance with the operating parameters to obtain a configured resonant charging supply; and integrating the configured resonant charging supply with the laser platform.

16. The method of claim 15, wherein: integrating the configured resonant charging supply with the laser platform comprises installing the configured resonant charging supply into the laser platform; and obtaining the one or more operating parameters of the laser platform is performed after installing the configured resonant charging supply with the laser platform.

17. The method of claim 16, wherein: obtaining the one or more operating parameters of the laser platform is performed in response to installing the configured resonant charging supply with the laser platform.

18. The method of claim 15, wherein obtaining one or more operating parameters of the laser platform includes obtaining one or more of operating voltage, operating current, charging inductor inductance, maximum operating voltage, maximum operating current, and maximum permissible repetition rate of the laser platform.

19. The method of claim 15, wherein configuring the unconfigured resonant charging supply includes one or more of adjusting the inductance of a variable inductor in the resonant charging supply, programming an energy control circuit in the resonant charging supply, programming a limiting voltage in the resonant charging supply, programming a limiting current in the resonant charging supply, programming a scaling voltage in the resonant charging supply, programming a scaling current in the resonant charging supply, and programming a maximum repetition rate for operation of the resonant charging supply.

20. A process of making a semiconductor device comprising configuring a resonant charging supply of a deep ultraviolet (DUV) light source and subsequently exposing a photoresist on a semiconductor substrate with light from the DUV light source, wherein the configuring comprises providing an unconfigured resonant charging supply; obtaining one or more operating parameters of a laser platform with which it is desired to use the unconfigured resonant charging supply; configuring the unconfigured resonant charging supply in accordance with the operating parameters to obtain a configured resonant charging supply; and integrating the configured resonant charging supply with the laser platform.

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