The present invention provides gas
discharge laser systems capable of reliable long-term operation in a
production line capacity at repetition rates in the range of 6,000 to 10,0000 pulses power second. Preferred embodiments are configured as KrF, ArF and F2 lasers used for light sources for
integrated circuit lithography. Improvements include a modified
high voltage power supply capable for charging an initial
capacitor of a magnetic compression pulse power
system to precise target voltages 6,000 to 10,0000 times per second and a
feedback control for
monitoring pulse energy and determining the target voltages on a pulse-by-pulse basis. Several techniques are disclosed for removing
discharge created debris from the
discharge region between the
laser electrodes during the intervals between discharges. In one embodiment the width of the discharge region is reduced from about 3 mm to about 1 mm so that a gas circulation
system designed for 4,000 Hz operation could be utilized for 10,000 Hz operation. In other embodiments the gas flow between the electrodes is increased sufficiently to permit 10,000 Hz operation with a discharge region width of 3 mm. To provide these substantial increased gas flow rates, Applicants have disclosed preferred embodiments utilize tangential forms of the prior art but with improved and more powerful motors and novel bearing designs. New bearing designs include both
ceramic bearings and magnetic bearings. In other embodiments, some or all of the gas circulation power is provided with a blower located outside the
laser chamber. The outside blower can be located in the laser cabinet or in separate location.