Effect of dual-pulse laser incident angle on the characteristics of tin plasma

A laser-produced plasma extreme ultraviolet light source is currently the only light source available for advancing the lithographic feature size into the 7 nm and beyond node. To further improve the extreme ultraviolet conversion efficiency (EUV-CE), in-depth research into the radiation mechanisms of plasma is essential. This paper presents a comparative analysis between the collinear and non-collinear dual-pulse laser irradiation tin (Sn) target schemes, revealing that the non-collinear scheme can effectively enhance the energy deposition of the main-pulse CO2 laser, reduce energy loss due to Sn plasma expansion, and increase both the radiation energy and radiation range of Sn plasma. Simulation results indicate that the maximum EUV-CE reaches 5.98% when the dual-pulse laser incident angle θ is set to 20°, representing an improvement of approximately 22.8% compared to the collinear scheme.