EUV Lithography: Past, Present and Future

ASML started a program to select the “Next Generation Lithography” in 1997 with active participation on Electron Beam Projection Lithography, Ion Beam Projection Lithography as well as Extreme Ultraviolet (EUV) Lithography. These technologies have been explored by various consortia worldwide, EUV Lithography since the mid 80’s. The extendibility to smaller nodes was a decisive advantage for EUV and by 2001 ASML decided to focus on EUV. By 2006 ASML shipped the first two full field scanners, with a Numerical Aperture (NA) equal to 0.25 EUV Alpha-demo tools. These tools have been instrumental to boost the learning on mask and resist, yet significant innovations in e.g. source power were needed before EUV could enter into High Volume Manufacturing (HVM). Today EUV NA=0.33 is being used in HVM of logic as well as DRAM IC makers and the first NA=0.55 scanners have been shipped. ASML and Zeiss are currently exploring next steps in our EUV roadmap, including a “hyper-NA” system with a NA>0.7. Such a scanner could extend the single patterning capabilities down to 5 nm lines & spaces (L/S). Further improvements on the resist are key to utilize current and future EUV scanners to their full potential.