Extreme ultraviolet (EUV) lithography is currently entering high-volume manufacturing to enable the continued miniaturization of semiconductor devices. The required EUV light, at 13.5 nm wavelength, is produced in a hot and dense laser-driven tin plasma. The atomic origins of this light are demonstrably poorly understood. Here we calculate detailed tin opacity spectra using the Los Alamos atomic physics suite ATOMIC and validate these calculations with experimental comparisons. Our key finding is that EUV light largely originates from transitions between multiply-excited states, and not from the singly-excited states decaying to the ground state as is the current paradigm. Moreover, we find that transitions between these multiply-excited states also contribute in the same narrow window around 13.5 nm as those originating from singly-excited states, and this striking property holds over a wide range of charge states. We thus reveal the doubly magic behavior of tin and the origins of the EUV light.

Additional Metadata
Keywords General Biochemistry, Genetics and Molecular Biology, General Physics and Astronomy, General Chemistry
Publisher Springer Nature
Funder ERC , NWO
Persistent URL dx.doi.org/10.1038/s41467-020-15678-y
Journal Nature Commun.
Torretti, F, Sheil, J, Schupp, R, Basko, M.M, Bayraktar, M, Meijer, R.A, … Colgan, J. (2020). Prominent radiative contributions from multiply-excited states in laser-produced tin plasma for nanolithography. Nature Commun., 11(1), 2334: 1–2334: 8. doi:10.1038/s41467-020-15678-y