Radiation-Dominated Plasma in LPP Sources: Physical Aspects and Challenges for Numerical Modeling

Basko, Mikhail M.

doi:10.1117/3.2638242.ch5

Book: Photon Sources for Lithography and Metrology

Editor(s): Vivek Bakshi

Author(s): Mikhail Basko

Published: 2023

https://doi.org/10.1117/3.2638242.ch5

Abstract

The main content of the chapter, presented in Sections 5.3–5.6, is focused on presentation and analysis of the results obtained in the process of solving several specific problems. Section 5.3 tackles the problem of validation of a RHD code against documented EUVL-related experiments. As such, laser ablation of planar Sn films deposited on a Si substrate and laser propulsion of spherical Sn droplets11 are selected. For the propulsion experiments, where the measured quantity (the propulsion velocity) depends primarily on the integral (i.e., frequency- and angle-averaged) characteristics of radiation–matter interaction, an excellent agreement between the experiment and the RALEF results is established. For the planar Sn ablation, where the CE as a function of the Sn film thickness was measured, also a fair—though less accurate—agreement is found. In this latter case, comparison with experiment is complicated by a relatively high sensitivity of the measured CE to the details of the experimental setup, and of the calculated CE to uncertainties in the theoretical Sn opacities; also, the inability of the RALEF code to model mixing between the Sn and underlying substrate turned out to be an issue.