RADIATION SOURCE AND METHOD FOR LITHOGRAPHIC APPARATUS AND DEVICE MANUFACTURING METHOD

摘要

A radiation source for generating EUV from a stream of molten fuel droplets by LPP (Laser Produced Plasma) or (Dual Laser Plasma) has a fuel droplet generator arranged to provide a stream of droplets of fuel (314) and at least one laser configured to vaporize at least some of the droplets of fuel, whereby radiation is generated. The fuel droplet generator has a nozzle (301), a feed chamber, and a reservoir (303), with a pumping device arranged to supply a flow of fuel in molten state from the reservoir through the feed chamber and out of the nozzle as a stream of droplets. The feed chamber has an outer face in contact with a drive cavity (310) filled with a liquid, and the liquid is driven to oscillate by a vibrator (311) with the oscillation transmissible to the molten fuel in the feed chamber from the outer face of the feed chamber through the liquid. The arrangement permits oscillatory driving of a nozzle feed chamber to control fuel stream breakup into droplets without need for direct contact between a vibrator and the fuel nozzle feed chamber. This may reduce risk of loss of transmission from vibrator to feed chamber through contact failure and may allow for remote positioning of the vibrator at a cooled location for efficient operation.