Boxing with tin droplets to generate EUV light

ASML’s state-of-the-art nanolithography machines use microscopically small tin droplets to generate EUV light. Firing intense laser pulses at these droplets results in a very hot plasma that emits the desired light. ‘A laser-produced plasma is a good source for EUV light,’ says Oscar Versolato of the Advanced Research Center for Nanolithography (ARCNL). ‘The laser heats the droplet to a million degrees Celsius, to the point where the tin atoms shed off a large fraction of their electrons. Energetic processes, such as collisions, involving these electrons and their parent tin atomic ions lead to the emission of the desired EUV light.’

The light-generating sequence is not at all straightforward, however. ARNCL was established in January 2014 at ASML’s initiative for exactly that reason: to carry out fundamental research that has relevance for key technologies in nanolithography. The centre forms a public-private partnership between the Foundation for Fundamental Research on Matter (FOM), the Netherlands Organisation for Scientific Research (NWO), the University of Amsterdam, the Vrije Universiteit Amsterdam and ASML.