Patent ID: 6714577
Filing Date: 2004-03-30
Classification: G03F,H01S

Abstract:
An excimer or molecular fluorine laser, comprising:a discharge chamber initially filled with a gas mixture at least including molecular fluorine, a buffer gas and an amount between 100 ppm and 2000 ppm of xenon; a plurality of electrodes in the discharge chamber connected to a discharge circuit for energizing the gas mixture by applying predetermined driving voltages to the electrodes at a repetition rate of at least one kilohertz; as resonator including a line-narrowing and wavelength tuning module and the discharge chamber for generating an output laser beam at a specified energy, a gas supply unit coupled with the discharge chamber and configured to permit a quantity of a molecular fluorine/buffer gas mixture less than two mbar to inject into said discharge chamber at selected intervals; an energy detector for monitoring energies of the output beam; a wavelength meter for monitoring wavelengths of the output beam; a processor for receiving values of the energies and wavelengths and including a signal indicative of a concentration of the molecular fluorine in the gas mixture, the processor controlling the line-narrowing and wavelength tuning module to tune the wavelength, the discharge circuit to control the energy of the output beam and the gas supply unit to control the concentration of the molecular fluorine in the gas mixture, and wherein values of the predetermined driving voltages are selected by the processor based on the received values of the energies, and wherein the amount of the xenon in the gas mixture is selected to provide enhanced pulse-to-pulse energy stability, such that the overall stability of output beam parameters including pulse-to-pulse energy stability and wavelength is enhanced, and wherein the selected values of the predetermined driving voltages are influenced by the presence of the xenon in the gas mixture for providing the output beam at the specified energy.