Tin laser-produced plasma as the light source for extreme ultraviolet lithography high-volume manufacturing: history, ideal plasma, present status, and prospects

Today intermediate-focus equivalent extreme ultraviolet (EUV) power of several watts is now available, and EUV lithography scanners are being considered as potential scanners for high-volume manufacturing (HVM) tools. However, for high-volume manufacturing with throughput of over 100 wafers per hour, EUV power of 350 W may be required. We review the history of EUV sources for lithography with tin as fuel. We discuss the ideal plasma for tin sources for extreme ultraviolet lithography (EUVL), conditions for a high conversion efficiency of 4% to 5% in 2 pi sr, and the existence of a repetition rate limit at around 40 kHz. We review the present status reported by EUV source suppliers and the prospects of tin laser-produced plasma as an EUV source for HVM EUVL. (c) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.JMM.11.2.021109]