Plasma and Fusion Research

Volume 20, 2401007 (2025)

Regular Articles


Modeling of EUV Spectrum from Laser-Produced Sn Plasmas
Akira SASAKI
Kansai Institute of Photon Science, National Institutes for Quantum Science and Technology, Kyoto 619-0215, Japan
(Received 24 July 2024 / Accepted 26 September 2024 / Published 22 January 2025)

Abstract

We investigate extreme-ultra-violet (EUV) emission from laser-produced tin plasmas for its application to microlithography. Strong emission occurs through 4d-4f and 4p-4d transitions, which appear as an unresolved transition array (UTA) due to the effect of configuration interaction (CI). Emissions from 8 to 13 times ionized tin overlap in the same λ=13.5 nm band, and both singly and multiply excited states of each ion contribute to the emission. We develop the collisional radiative model of tin ions, taking into account an appropriate set of atomic states that have a large population to contribute to the emission. The model is being validated through comparisons between the calculated and observed spectrums.


Keywords

atomic processes in plasmas, plasma spectroscopy, EUV, lithography, multiply charged ion, tin

DOI: 10.1585/pfr.20.2401007


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