SUPERNARROW BAND, TWO CHAMBER, HIGH REP RATE GAS DISCHARGE LASER SYSTEM

摘要

PROBLEM TO BE SOLVED: To generate a high-quality pulse laser beam by a pulse speed of approximately 4,000 Hz or more, and a pulse energy of approximately 5 mJ or more. SOLUTION: Two discharge chambers are provided. One is a portion of a main oscillator for generating a supernarrow band seed beam, and the seed beam is amplified in a second discharge chamber. The discharge chambers can be independently controlled so that individual optimization in a wavelength parameter of the main oscillator, and optimization in the pulse energy parameter of an amplification chamber can be made. A preferred embodiment is an ArF excimer laser system that is composed as an MOPA, and is specially designed for a light source for integrated-circuit lithography. In an MOPA embodiment, each chamber has a single tangential fan for generating gas flow that can be operated by a pulse speed of 4,000 Hz or more by removing a residue from a discharge region at time that is less than approximately 0.25 mm between pulses.