Gas laser apparatus for lithography

摘要

The present invention relates to a long pulse gas laser apparatus for lithography further improved in the laser oscillation efficiency and stability increased by addition of xenon gas. A gas laser apparatus for lithography has a pair of discharge electrodes 2 provided in a laser chamber 1 and emits laser beam having a laser pulse width (T_is) of not less than 40 ns by exciting a laser gas sealed in the laser chamber 1 by electric discharge between the pair of discharge electrodes 2 , the laser gas containing xenon in an amount not less than 2 ppm and not more than 100 ppm in partial pressure ratio. The laser gas has been heated at least when the laser beam is emitted.