CO2 laser-produced tin plasmas for next generation semiconductor lithography sources Thomas Cummins , Gerry O’Sullivan, Emma Sokell, Padraig Dunne, Fergal O’Reilly, Paul Sheridan and Tony Donnelly Atomic, Molecular and Plasma Spectroscopy group, School of Physics, University College Dublin, Belfield, Dublin 4, Ireland Abstract Measurements of the in-band Extreme-Ultraviolet (EUV) emission from CO2 laser produced Sn (tin) plasma were recorded in order to obtain conversion efficiency values for next generation EUV Lithography sources. CE values were recorded for different laser gas mixtures, with maximum CE values of around 1.5% achieved. 1. Introduction In order to progressively reduce the transistor size on silicon microchips for the continuation of Moore’s Law, next generation Lithography processes for the semiconductor industry require the implementation of Extreme-Ultraviolet (EUV) light sources. An EUV lithography source operating at 13.5 ± 1% nm has been proposed to match the availability of Mo/Si multilayer mirrors and a Sn laser produced plasma is proposed as the source emitter due a large broadband emission feature centred at 13.5 nm for plasma in the temperature range of 30 – 40 eV. The research to date surrounding EUV emitting tin plasmas for lithography has mainly concentrated on using pulsed lasers operating at 1064 nm but theoretical modelling [1] and recent experiments [2] have shown that a move to CO 2 lasers operating at 10600 nm will have more intense in-band EUV emission at lower power densities, thus improving the EUV conversion efficiency. Consequently, we have measured the in-band (centred on 13.5 nm) and broadband EUV emission of a CO 2 laser produced tin plasma using a 0.25-m, absolutely calibrated spectrometer operating in the 9 – 17 nm spectral region. We have done this for a range of laser power densities and the EUV conversion efficiency has been measured at 45° to the target surface normal. A Sn target was placed inside a vacuun chamber, which was kept at a pressure of 1x10 -6 mbar. The laser energy was delivered by a CO 2 laser with 10 Hz max repetition rate, a max energy of 2 J and 20-70 ns pulse duration. The laser beam was focussed using a 5 cm 37 th EPS Conference on Plasma Physics P2.234