Abstract: An apparatus measures a spectral distribution of a narrow-band laser beam generated by a line-narrowed excimer laser or a molecular fluorine laser system. The apparatus includes an an interferometric device disposed along an optical path of an output beam of the laser system such that the beam traverses the interferometric device on a first pass, a retro-reflector disposed after the interferometric device along the optical path for retro-reflecting the beam back through the interferometric device on a second pass, and a detector for detecting an intensity of the beam after the second pass through the interferometric device. Preferably, spectral information is determined when the free spectral range of the interferometric device is tuned and the detector measures the intensity of the beam at a plurality of free spectral ranges or when the wavelength of the output beam is tuned.

Abstract: An excimer or molecular fluorine laser system includes a wavelength calibration module permitting the wavelength of the narrow band output beam to be calibrated to a specific absolute wavelength. The module is preferably a lamp which contains at least one species including platinum with an optical transition within the emission spectrum of the laser system. Light from the lamp is preferably coincident at a spectrometer with a beam portion from the laser, and the laser beam wavelength is calibrated by simultaneous analysis at the spectrograph.

Abstract: In an excimer laser or a molecular fluorine laser, a heating element is used which is heated to temperatures in excess of 60° C., in order to remove impurities from the laser gas.

Abstract: A method of operating a laser system for increasing the lifetimes of optical components of the resonator includes the steps of configuring the laser system to initially output laser pulses at an energy in a range above a predetermined energy for industrial lithographic processing, and attenuating the energy of the output pulses to the predetermined energy. A further step includes reducing an amount of attenuation as optics of the laser resonator age to maintain the laser pulses at the predetermined energy, or reducing the amount of attenuation to produce pulses having a higher energy than the predetermined energy.

Abstract: A wavelength chirp compensation method for an excimer or molecular fluorine laser system operating in burst mode, includes pre-programming into a computer of the laser system resonator tuning optic adjustments for making the adjustments during pauses between bursts to compensate wavelength chirp at beginnings of succeeding bursts.

Abstract: A method and gas replenishment algorithm for excimer and molecular fluorine lasers is based on parameters upon which gas aging more closely depends than pulse count, such as input energy to the electrical discharge, and also preferably time. A burst control method and algorithm includes measuring the energies of initial pulses of a first burst occurring after a long burst break, calculating values of input voltages for the initial pulses that would bring output energies of the individual laser pulses or groups of pulses to substantially the same values, and applying the calculated voltages in a subsequent first burst after a long burst break to achieve substantially same predetermined output energy values for the pulses or groups of pulses. Similar operations may be performed for one or more subsequent bursts following the first burst.

Abstract: An excimer or molecular fluorine laser system is provided which emits a laser beam during operation and has a gas mixture with a gas composition initially provided within a discharge chamber. The laser system includes a discharge chamber containing a laser gas mixture at least including a halogen-containing species and a buffer gas, multiple electrodes within the discharge chamber and connected to a discharge circuit for energizing the gas mixture, a resonator for generating a laser beam, an electrostatic precipitator for having a voltage applied thereto and for receiving and precipitating contaminant particulates from a flow of the gas mixture, and a processor for monitoring the corona discharge ignition voltage of the electrostatic precipitator and for determining a status of said gas mixture based on the monitored voltage.

Abstract: A F2-laser includes a discharge chamber filled with a gas mixture including molecular fluorine for generating a spectral emission in a wavelength range between 157 nm and 158 nm including a primary line and a secondary line, multiple electrodes coupled with a power supply circuit for producing a pulsed discharge to energize the molecular fluorine, a resonator including the discharge chamber and an interferometric device for generating a laser beam having a bandwidth of less than 1 pm, and a wavelength monitor coupled in a feedback loop with a processor for monitoring a spectral distribution of the laser beam. The processor controls an interferometric spectrum of the interferometric device based on the monitored spectral distribution such that sidebands within the spectral distribution are substantially minimized.

Abstract: An excimer or molecular fluorine laser, such as a KrF- or ArF-laser, or a molecular fluorine (F2) laser, particularly for photolithography applications, has a gas mixture including a trace amount of a gas additive. The concentration of the gas additive in the gas mixture is optimized for improving energy stability and/or the overshoot control of the laser output beam. The concentration is further determined and adjusted at new fills and/or during laser operation based on its effect on the output pulse energy in view of constraints and/or aging on the discharge circuit and/or other components of the laser system. Attenuation control is also provided for increasing the lifetimes of components of the laser system by controlling the concentration of the gas additive over time. A specific preferred concentration of xenon is more than 100 ppm for improving the energy stability and/or overshoot control.

Abstract: An E-Diagnostic system for monitoring a state of an excimer laser or molecular fluorine laser system includes a processing device and an interface. The processing device runs a program for outputting parameter requests to the laser system, receiving parameter values from the laser system in response to the parameter requests, and storing the parameter values such that a record of the state of the excimer or molecular fluorine laser system is kept. The interface signal-couples the processing device with the laser system permitting the outputting of the parameter requests and the receiving of the parameter values between the processing device and the laser system.

Abstract: A gas discharge laser system for generating a laser beam, such as an excimer or molecular fluorine laser system, includes a laser resonator with an optical element for making wavefront corrections such as an adaptable optical element, a phase conjugating mirror, or a retroreflector array. The resonator preferably also has one or more line-narrowing optical elements for narrowing the bandwidth of the laser beam. One of the resonator reflectors or a transmissive or reflective intracavity optical element of the laser may include the adaptable optical element, phase conjugating mirror or retroreflector plate. A beam expander may be disposed before the adaptable optical element, phase conjugating mirror or retroreflector array for increasing the radius of curvature of the wavefront of the laser beam. A detection and control system including a processor and a detector may be used for controlling the contour of the wavefront correcting optical element in a feedback loop.

Abstract: A molecular fluorine laser includes a discharge chamber filled with a gas mixture including molecular fluorine and a buffer gas and not including a laser active rare gas, multiple electrodes within the discharge chamber defining a discharge region therebetween connected to a pulsed discharge circuit for applying discharge pulses to the electrodes for energizing the gas mixture, and a resonator including the discharge chamber for generating an oscillator laser beam at a wavelength around 157 nm and a bandwidth of less than 0.6 pm. The laser further includes a power amplifier for increasing the energy of the attenuated oscillator laser beam to a second predetermined energy for lithographic processing, a line-narrowing unit for reducing the bandwidth, a low intensity suppressor module to suppress the weaker lines of the F2-laser, and a synchronization unit to synchronize the oscillator and amplifier.

Abstract: An efficient F2 laser is provided with improvements in line selection, monitoring capabilities, alignment stabilization, performance at high repetition rates and polarization characteristics. Line selection is preferably provided by a transmission grating or a grism. The grating or grism preferably outcouples the laser beam. The line selection may be fully provided at the front optics module. A monitor grating and an array detector monitor the intensity of the selected (and unselected) lines for line selection control. An energy detector is enclosed in an inert gas purged environment at slight overpressure. A blue or green reference beam is used for F2 laser beam alignment stabilization and/or spectral monitoring of the output laser beam. The blue or green reference beam advantageously is not reflected out with a atomic fluorine red emission of the laser and is easily resolved from the red emission.

Abstract: A device for use with a repetitively pulsed gas laser provides self-initiated UV preliminary ionization of the active volume of a laser, which has extended high-voltage and grounded electrodes disposed parallel to one another, to which peaking capacitors distributed along the length of the electrodes are connected in a low-inductance manner. The low-voltage contacts of the peaking capacitors are either connected directly to the grounded electrode or, if this connection is interrupted, dielectric plates are inserted that are disposed either on one side or on both sides of the grounded electrode. If the capacitors are charged rapidly, a surface discharge which effects UV pre-ionization of the volume of the main discharge and is uniformly distributed over the whole surface of the dielectric plates is produced on the surface of the dielectric plates.

Abstract: A wavemeter for monitoring a wavelength of emission from a tunable laser includes a spectrometer disposed within a housing having a controlled pressure, and a temperature sensor and/or a pressure sensor for sensing the temperature and/or pressure, respectively, within the housing. The temperature and/or pressure are controlled such that they have relative values, and materials are selected, each for substantially minimizing temperature sensitivity of the spectrometer, such as for providing a temperature sensitivity of the spectrometer within ±0.1 pm/°K.

Abstract: An excimer or molecular fluorine laser system includes a discharge chamber filled with a gas mixture, multiple electrodes within the discharge chamber and connected to the discharge circuit for energizing the gas mixture, a resonant cavity including the discharge chamber for generating a laser beam, and an intracavity homogenizer for homogenizing an intensity profile of the laser beam generated in the resonator. The intracavity homogenizer may include each of a first bi-prism and a second bi-prism disposed at opposite ends of the resonant cavity and having the discharge chamber disposed therebetween. In this case, optical axes of the first bi-prism and the second bi-prism are each at least substantially parallel to the optical axis of the laser beam.

Abstract: A preionization device for a gas laser comprises an internal preionization electrode having a dielectric housing around it and an external preionization electrode displaced from the dielectric housing by a small gap. The dielectric housing includes two cylindrical regions of differing outer radii of curvature. An open end of the housing has a larger radius of curvature than the other end which is closed. The internal electrode connects to circuitry external to the discharge chamber via a conductive feedthrough which penetrates through the housing. The external circuitry prevents voltage oscillations caused by residual energy stored as capacitance in the dielectric housing. The external preionization electrode, which is connected electrically to one of the main discharge electrodes, is formed to shield the internal preionization electrode from the other main discharge electrode to prevent arcing therebetween.

Abstract: A tunable laser system includes a gain medium and an optical resonator for generating a laser beam, and a spectral narrowing and tuning unit within the resonator. A detection and control unit controls a relative wavelength of the laser system. A wavelength calibration module calibrates the detection and control unit. The module contains more than one species each having an optical transition line within the tuning spectrum of the laser.

Abstract: A beam characterization monitoring apparatus receives an input VUV beam and measures a beam profile characteristic of the beam. An enclosure has an interior substantially free of VUV photoabsorbing species and configured for receiving the input VUV beam therein. Optics within the enclosure separate the input VUV beam into a first component for measuring a near field beam profile characteristic and a second component for measuring a far field beam profile characteristic. A detector coupled with the enclosure via a beam path substantially free of VUV photoabsorbing species preferably detects the first and second components simultaneously. A quantum converter is preferably disposed along the beam path before the detector for converting the VUV beam to a beam having a wavelength above 240 nm. A second detector preferably detects an energy of an additional component of the input VUV beam.

Abstract: A preionization device for a gas laser comprises an internal preionization electrode having a dielectric housing around it and an external preionization electrode displaced from the dielectric housing by a small gap. The dielectric housing includes two cylindrical regions of differing outer radii of curvature. An open end of the housing has a larger radius of curvature than the other end which is closed. The internal electrode connects to circuitry external to the discharge chamber via a conductive feedthrough which penetrates through the housing. The external circuitry prevents voltage oscillations caused by residual energy stored as capacitance in the dielectric housing. The external preionization electrode, which is connected electrically to one of the main discharge electrodes, is formed to shield the internal preionization electrode from the other main discharge electrode to prevent arcing therebetween.