Kinetic modeling of ion acceleration in laser-driven tin plasma EUV sources
ORAL
Abstract
Laser-produced tin plasmas are enabling the continuation of Moore's law through the use of 13.5 nm narrow-band EUV radiation for next generation lithography. A major challenge for their industrial application is damage to the sensitive optics from energetic ions produced during the laser-plasma interaction. In this work we use fully kinetic PIC simulations to study the ion acceleration mechanisms in tin plasma EUV sources, utilizing an inverse-bremsstrahlung heating operator to model the interaction of a tin target with an Nd:YAG laser and a Monte-Carlo Coulomb collision operator to model thermal conduction. These simulations capture the global source evolution while allowing for detailed analysis of energetic ion trajectories. Benchmarking tests against analogous single-fluid radiation hydrodynamics simulations show qualitative agreement in most of the domain. However, the long timescales for thermal equilibration in the ablated plasma allow for the development of two-temperature features in the PIC simulation. A collimated population of energetic ions is produced in the PIC simulation with a significant enhancement at the highest energies compared to the fluid simulations. The dominant acceleration mechanism is a large-scale electric field supported by the electron pressure gradient, which becomes stronger in the kinetic simulations due to the increased electron temperature. We discuss the implications for advancing the modeling of these sources and developing debris mitigation schemes.
*The research described in this paper was conducted under the Laboratory Directed Research and Development (LDRD) Program at Princeton Plasma Physics Laboratory, a national laboratory operated by Princeton University for the U.S. Department of Energy under Prime Contract No. DE-AC02-09CH11466. Part of this work has been carried out at the Advanced Research Center for Nanolithography (ARCNL), a public-private partnership of the University of Amsterdam (UvA), the Vrije Universiteit Amsterdam (VU), associate partner the University of Groningen, NWO-I, and the semiconductor equipment manufacturer ASML.
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Publication:S. R. Totorica, K. Lezhnin, D. J. Hemminga, J. Gonzalez, J. Sheil, A. Diallo, A. Hyder, W. Fox, "Acceleration mechanisms of energetic ion debris in laser-driven tin plasma EUV sources", Applied Physics Letters 124, 174101 (2024).
