Debris Generation from CO_2 and Nd:YAG Laser-Produced Tin Plasmas for EUV Light Source

摘要

The results of a comparative investigation on the emission characteristics of debris from CO_2 laser-produced tin plasma and Nd: YAG laser-produced tin plasma for an extreme ultraviolet lithography (EUV) light source. The tin ions and droplets emitted from tin plasma produced by a CO_2 laser or an Nd: YAG laser were detected with Faraday cups and quartz crystal micro-balance (QCM) detectors, respectively. The large size of droplets was also observed by silicon substrates as witness plates. A higher ion kinetic energy and lower debris emission in the case of CO_2 laser in compared with Nd: YAG laser for the same laser energy of ～50 mJ. In addition, the dynamics of the neutral atoms and the irradiated target from an Nd:YAG laser-produced tin plasma with a mass-limited micro-droplet target were investigated by imaging techniques.