Laser-produced tin (Sn) plasma is extensively used as an extreme ultraviolet (EUV) light source for advanced lithography; however, the collector mirror lifetime is considerably shortened by high-energy debris from the plasma. The introduction of hydrogen (H2) gas into the plasma region can mitigate debris through ion–neutral collisions and chemical reactions forming gaseous stannane (SnH4). However, the detailed Sn-H interaction mechanisms remain uninvestigated. Herein, visible emission spectroscopy was used to investigate the spatiotemporal behaviors of Sn and H plasmas generated by 12-ps, 1,064-nm laser pulses incident on a solid Sn target in a 100 Pa H2 atmosphere. Spatiotemporal-resolved measurements of Hα and Hβ lines revealed prompt hydrogen excitation following plasma generation, with electron temperatures of 1–2 eV and electron densities up to 1 × 1017 cm−3 near the target. These conditions aid the formation of hydrogen radicals that react with Sn atoms/ions to produce SnH4, contributing to the effective mitigation of debris. These findings offer insights into the optimization of the EUV source performance and the prolongation of the optical component lifetime.
GAO et al. (Thu,) studied this question.