LINE SELECTED F2 TWO CHAMBER LASER SYSTEM

摘要

An injection seeded modular gas discharge laser system (2) capable of producing high quality pulsed laser beams at pulse rates of about 4,000 Hz o r greater and at pulse energies of about 5 mJ or greater. Two separate dischar ge chambers are provided, one of which is a part of a master oscillator (10) producing a very narrow band seed beam, which is amplified (12) in the secon d discharge chamber. The chambers can be controlled separately permitting separate optimization of wavelength parameters in the master oscillator and optimization of pulse energy parameters in the amplifying chamber. A preferr ed embodiment in the ArF excimer laser system configured as a MOPA and specifically designed for use as a light source for integrated circuit lithography. In the preferred MOPA embodiment, each chamber comprises a sing le tangential fan (10A) providing sufficient gas flow to permit operation at pulse rates of 4000 Hz or greater by clearing debris from the discharge regi on in less time than the approximately 0.25 milliseconds between pulses. The masters oscillator is equipped with a line narrowing package having a very fast tuning mirror capable of controlling centerline wavelength an a pulse t o pulse basis at repetition rates of 4,000 Hz or greater to precision of less that 0.2 pm.