Abstract: Disclosed is an apparatus for and method of measuring the concentration of F2 in the laser gas used in an excimer laser. Quartz Enhanced Photoacoustic Spectroscopy is used to obtain a direct measurement of F2 concentration quickly and using only a small sample volume.

Abstract: In a method, energy is supplied to a first gas discharge chamber of a first stage until a pulsed amplified light beam is output from the first stage and directed toward a second stage. While the energy is supplied to the first gas discharge chamber: a value of an operating parameter of the first gas discharge chamber is measured; it is determined whether to adjust an operating characteristic of the first gas discharge chamber based on the measured value; and, the operating characteristic of the first gas discharge chamber is adjusted if it is determined that the operating characteristic of the first gas discharge chamber should be adjusted. After it is determined that the operating characteristic of the first gas discharge chamber no longer should be adjusted, then an adjustment procedure is applied to an operating characteristic of a second gas discharge chamber of the second stage.

Abstract: A method to improve a lithographic process of imaging a portion of a design layout onto a substrate using a lithographic apparatus, the method including: computing a multi-variable cost function, the multi-variable cost function being a function a plurality of design variables that represent characteristics of the lithographic process; and reconfiguring one or more of the characteristics of the lithographic process by adjusting one or more of the design variables until a certain termination condition is satisfied; wherein a bandwidth of a radiation source of the lithographic apparatus is allowed to change during the reconfiguration.

Abstract: A method and apparatus for controlling a dose of radiation generated by a laser light source is disclosed. In one embodiment, a dose controller receives measurements of the deviation of output energy from an expected output energy, or “energy sigma,” and the standard deviation of the error in the dose received by the item being processed from the desired dose. The ratio of the energy sigma to the standard deviation of dose error is calculated, and the laser controller adjusts the controller gain based upon the calculated ratio so as to adjust the voltage determined by the controller, and consequently the output energy and thus the dose to the item. This is an improvement over the prior art, in which the controller gain is adjusted based upon sending a voltage dither to the laser and correlating it to its response in energy at only one frequency.

Abstract: Methods and apparatus for in situ compensation for damage or misalignment of optical elements are disclosed. Also disclosed are methods and apparatus for facilitating alignment of replacement optical elements so that the amount of time in a system including the optical elements can be reduced. Also disclosed are methods and apparatus for processing an image of a beam generated by an optical system to extract information indicative of an extent of damage to optical elements in the optical system and/or misalignment of the optical elements. Information pertaining to an extent of damage to optical elements in the optical system can be used to optimally schedule maintenance events for the optical system.

Abstract: Wafer positioning errors in stepper-scanners contribute to imaging defects. Changing the wavelength of the light source's generated light can compensate for wafer positional errors in the Z-direction. The wafer's real-time z-position is determined and a change in wavelength target to offset this error is communicated to the light source. The light source uses this change in wavelength target in a feed-forward operation and, in an embodiment, in combination with existing feedback operations, on a pulse-by-pulse basis for subsequent pulses in a current burst of pulses in addition to receiving the newly-specified laser wavelength target for a subsequent burst of laser pulses.

Abstract: A gas discharge light source includes a gas discharge system that includes one or more gas discharge chambers. Each of the gas discharge chambers in the gas discharge system is filled with a respective gas mixture. For each gas discharge chamber, a pulsed energy is supplied to the respective gas mixture by activating its associated energy source to thereby produce a pulsed amplified light beam from the gas discharge chamber. One or more properties of the gas discharge system are determined. A gas maintenance scheme is selected from among a plurality of possible schemes based on the determined one or more properties of the gas discharge system. The selected gas maintenance scheme is applied to the gas discharge system. A gas maintenance scheme includes one or more parameters related to adding one or more supplemental gas mixtures to the gas discharge chambers of the gas discharge system.

Abstract: Anodes and cathodes for use in generating gas discharge laser light are disclosed. The improved anode has a transition portion that includes a substantially vertical sidewall to transition between the active portion and the end portion to reduce erosion-related issues. The improved cathode has thickened spine portions in enhanced erosion locations. The spine portions are thickened by removing material from the shoulder of the cathode stepped cross-section profile in those locations in order to improve the longevity of the cathode.

Abstract: A method of controlling output of a radiation source, the method including: periodically monitoring an output energy of the radiation source; determining a difference between a reference energy signal and the monitored output energy; determining a feedback value; determining a desired output energy of the radiation source for a subsequent time period; and controlling an input parameter of the radiation source in dependence on the determined desired output energy during the subsequent time period. If the magnitude of the determined difference between the monitored output energy of the radiation source and the reference energy signal exceeds a threshold value: the determined difference does not contribute to the feedback value; and the determined difference is spread over the subsequent time period according to a reference energy signal adjustment profile and the reference energy signal adjustment profile is added to the reference energy signal for the subsequent time period.

Abstract: A photolithography method includes instructing an optical source to produce a pulsed light beam; scanning the pulsed light beam across a wafer of a lithography exposure apparatus to expose the wafer with the pulsed light beam; during scanning of the pulsed light beam across the wafer, receiving a characteristic of the pulsed light beam at the wafer; receiving a determined value of a physical property of a wafer for a particular pulsed light beam characteristic; and based on the pulsed light beam characteristic that is received during scanning and the received determined value of the physical property, modifying a performance parameter of the pulsed light beam during scanning across the wafer.

Abstract: An indication of an output of an optical source of a photolithography system is accessed; an indication of an input provided to the optical source is accessed, the provided input being associated with the accessed indication of the output of the optical source; an output error is determined from an expected amount of output and the accessed indication of the output of the optical source; a local gain associated with the accessed indication of the input provided to the optical source is estimated; a gain error is determined from the estimated local gain and an expected local gain; a current value of one or more operating metrics of the optical source is estimated based on one or more of the output error and the gain error; and a gain relationship for the optical source is updated based on the estimated current value of the one or more operating metrics.

Abstract: A metrology system is used for measuring a spectral feature of a pulsed light beam. The metrology system includes: a beam homogenizer in the path of the pulsed light beam, the beam homogenizer having an array of wavefront modification cells, with each cell having a surface area that matches a size of at least one of the spatial modes of the light beam; an optical frequency separation apparatus in the path of the pulsed light beam exiting the beam homogenizer, wherein the optical frequency separation apparatus is configured to interact with the pulsed light beam and to output a plurality of spatial components that correspond to the spectral components of the pulsed light beam; and at least one sensor that receives and senses the output spatial components.

Abstract: A spectral feature of a pulsed light beam produced by an optical source is controlled by a method. The method includes producing a pulsed light beam at a pulse repetition rate; directing the pulsed light beam toward a substrate received in a lithography exposure apparatus to expose the substrate to the pulsed light beam; modifying a pulse repetition rate of the pulsed light beam as it is exposing the substrate. The method includes determining an amount of adjustment to a spectral feature of the pulsed light beam, the adjustment amount compensating for a variation in the spectral feature of the pulsed light beam that correlates to the modification of the pulse repetition rate of the pulsed light beam. The method includes changing the spectral feature of the pulsed light beam by the determined adjustment amount as the substrate is exposed to thereby compensate for the variation in the spectral feature.

Abstract: A photolithography method includes producing, from an optical source, a pulsed light beam; and scanning the pulsed light beam across a substrate of a lithography exposure apparatus to expose the substrate with the pulsed light beam including exposing each sub-area of the substrate with the pulsed light beam. A sub-area is a portion of a total area of the substrate. For each sub-area of the substrate, a lithography performance parameter associated with the sub-area of the substrate is received; the received lithography performance parameter is analyzed, and, based on the analysis, a first spectral feature of the pulsed light beam is modified and a second spectral feature of the pulsed light beam is maintained.

Abstract: An apparatus includes a material having an optical transition profile with a known energy transition; and a detector configured to detect a characteristic associated with the interaction between the material and the testing light beam. The testing light beam is either a primary light beam produced by an optical source or a calibration light beam. The apparatus also includes a spectral analysis module placed in a path of the primary light beam; and a control system connected to the detector and to the spectral detection system. The control system is configured to determine a reference spectral profile of the primary light beam based on the detected characteristic; compare the reference spectral profile of the primary light beam with a sensed spectral profile of the primary light beam output from the spectral detection system; and based on this comparison, adjust a scale of the spectral detection system.

Abstract: A spectral feature of a pulsed light beam produced by an optical source is adjusted by receiving an instruction to change a spectral feature of the pulsed light beam from a value in a first target range to a value in a second target range; regulating a first operating characteristic of the optical source; determining an adjustment to a second actuatable apparatus of the optical source; and adjusting the second actuatable apparatus by an amount based on the determined adjustment. The first operating characteristic is regulated by adjusting a first actuatable apparatus of the optical source until it is determined that the first operating characteristic is within an acceptable range of values. The adjustment to the second actuatable apparatus is determined based at least in part on: a relationship between the adjustment of the first actuatable apparatus and a spectral feature of the light beam, and the second target range.

Abstract: Techniques for controlling an optical system include accessing a measured value of a property of a particular pulse of a pulsed light beam emitted from the optical system, the property being related to an amount of coherence of the light beam; comparing the measured value of the property of the light beam to a target value of the property; determining whether to generate a control signal based on the comparison; and if a control signal is generated based on the comparison, adjusting the amount of coherence in the light beam by modifying an aspect of the optical system based on the control signal to reduce an amount of coherence of a pulse that is subsequent to the particular pulse.

Abstract: A lithography system includes an optical source configured to emit a pulsed light beam; a lithography apparatus including an optical system, the optical system being positioned to receive the pulsed light beam from the optical source at a first side of the optical system and to emit the pulsed light beam at a second side of the optical system; and a control system coupled to the optical source and the optical lithography apparatus, the control system configured to: receive an indication of an amount of energy in the pulsed light beam at the second side of the optical system, determine an energy error, access an initial control sequence, the initial control sequence being associated with the optical source, determine a second control sequence based on the determined energy error and the initial control sequence, and apply the second control sequence to the optical source.

Abstract: A method includes producing a pulsed light beam; directing the pulsed light beam toward a substrate mounted to a stage of a lithography exposure apparatus; scanning a pulsed light beam and the substrate relative to each other, including projecting the pulsed light beam onto each sub-area of the substrate and moving one or more of the pulsed light beam and the substrate relative to each other; determining a value of a vibration of the stage for each sub-area of a substrate; for each sub-area of the substrate, determining an amount of adjustment to a bandwidth of the pulsed light beam, the adjustment amount compensating for a variation in the stage vibration so as to maintain a focus blur within a predetermined range of values across the substrate; and changing the bandwidth of the pulsed light beam by the determined adjustment amount to thereby compensate for the stage vibration variations.

Abstract: A system and method for automatically performing gas optimization after a refill in the chambers of a two chamber gas discharge laser is disclosed. The laser is fired at low power, and the gas in the amplifier laser chamber bled if necessary until the discharge voltage meets or exceeds a minimum value without dropping the pressure below a minimum value. The power output is increased to a burst pattern that approximates the expected operation of the laser, and the amplifier chamber gas bled again if necessary until the voltage and an output energy meet or exceed minimum values, or until the pressure is less than a minimum value. The gas in the master oscillator chamber is then bled if necessary until the output energy of the master oscillator meets or falls below a maximum value, again without dropping the pressure in the chamber below the minimum value. While the pressure is adjusted, bandwidth is also measured and adjusted to stay within a desired range.