Microdroplet-tin plasma sources of EUV radiation driven by solid-state-lasers (Topical Review)
Plasma produced from molten-tin microdroplets generates extreme ultraviolet light for state-of-the-art nanolithography. Currently, CO2 lasers are used to drive the plasma. In the future, solid-state mid-infrared lasers may instead be used to eﬃciently pump the plasma. Such laser systems have promise to be more compact, better scalable, and have higher wall-plug eﬃciency. In this Topical Review, we present recent ﬁndings at the Advanced Research Center for Nanolithography (ARCNL) on using 1- and 2-µm-wavelength solid-state lasers for tin target preparation and for driving hot and dense plasma. The ARCNL research ranges from advanced laser development, over studies of ﬂuid dynamic response of droplets to impact, radiation-hydrodynamics calculations of, e.g., ion “debris”, (EUV) spectroscopic studies of tin laser-produced-plasma, to high-conversion eﬃciency operation of 2-µm-wavelength driven plasma.