Methods and apparatus are provided for cleaning and passivating laser discharge
chambers with plasmas. In one embodiment, an oxygen based plasma is formed in a
plasma source external to the laser discharge chamber by applying a radiofrequency
signal to oxygen containing gases. The oxygen based plasma is drawn into the laser
discharge chamber, where it reacts with contaminants and cleans internal surfaces.
After cleaning, a fluorine based plasma is formed in the plasma source and drawn
into the laser discharge chamber to passivate internal surfaces. In another embodiment,
cleaning with the oxygen based plasma is not used since some level of cleaning
is accomplished with the fluorine based plasma. In another embodiment, oxygen based
plasmas and fluorine based plasmas are formed in the laser discharge chamber by
applying a radiofrequency signal to a laser discharge chamber electrode. Plasma
cleaning and passivation of laser discharge chambers is safer, more efficient,
and more effective than conventional thermal cleaning and passivation processes.
