EUV generation using water droplet target

摘要

In this paper, we described a laser plasma source for Extreme Ultraviolet Lithography (EUVL) based on a water droplet target. We successfully generated stable multi-kHz water droplets with several hundred μm diameter using our experimental setup. We realized a good synchronization of laser with droplet by employing droplet-probing photo diode (PD) signal to trig YAG laser timely. We got EUV emission with pulse to pulse stability of 3.4% (1σ) from this droplet plasma. We experimentally demonstrated that a 1kHz water droplet could be effectively supplied to reach laser focus region without being destroyed due to hot laser plasma formation from the previous droplet.