The effects of using axial magnetic field in extreme ultraviolet photon sources for nanolithography – recent integrated simulation

Abstract

We developed a comprehensive model for simulating laser/target interaction in the presence of external axial magnetic fields. The model was integrated into the framework of the HEIGHTS-LPP computer simulation package and benchmarked with recent experimental results. The package was then used to study the angular distribution of extreme ultraviolet (EUV) photon output in plasmas produced in tin planar targets by a Nd:YAG laser. A moderate (0.5 T) permanent magnetic field does not affect EUV source evolution and output. More effective control of plasma plume expansion should be based on magnetic field gradients, that is, on the temporary varying magnetic fields as a magnetic pinch. Analysis of angular EUV output showed strong anisotropy of photon emissions. We found that the correct monitoring angle (i.e., at which the measured EUV flux corresponds to the averaged value after the correctly integrated angular distribution) does not depend on laser irradiance in the studied range and is equivalent to ~60°. We recommend arranging the EUV sensors accordingly in experiments with planar tin targets.

Recycling of laser and plasma radiation energy for enhancement of extreme ultraviolet sources for nanolithography

“…The comprehensive computer code HEIGHTS (High Energy Interaction with General Heterogeneous Target Systems) has been successfully developed and benchmarked at Purdue CMUXE (Center for Materials Under eXtreme Environments) over the years to analyze various aspects of plasma physics phenomena. [15][16][17][18] The HEIGHTS integrated package combines state-of-the art full 3D models of energy deposition, vapor/plasma formation/ evolution and magnetohydrodynamic (MHD) processes, thermal conduction in materials and in plasma, atomic physics and resulting opacities, detailed photon radiation transport, and interaction between plasma/radiation and target materials.…”

Liquid lithium as divertor material to mitigate severe damage of nearby components during plasma transients

“…The gyrokinetic model describes the rarefied hot core plasma, while the MHD model simulates evolution of the dense secondary plasma initiated after divertor vaporization. The secondary plasma (Li in this case) is several orders denser than the rare core plasma and the MHD treatment is justified for the dense plasma 13 . Our simulations predicted density of secondary plasma up to ~ 10 17 cm −3 in comparison to ~ 10 13 cm −3 for the hydrogen plasma.…”