Ambient gas effects on the dynamics of laser-produced tin plume expansion

Abstract

Controlling the debris from a laser-generated tin plume is one of the prime issues in the development of an extreme ultraviolet lithographic light source. An ambient gas that is transparent to 13.5nm radiation can be used for controlling highly energetic particles from the tin plume. We employed a partial ambient argon pressure for decelerating various species in the tin plume. The kinetic energy distributions of tin species were analyzed at short and large distances using time and space resolved optical emission spectroscopy and a Faraday cup, respectively. A fast-gated intensified charged coupled device was used for understanding the hydrodynamics of the plume’s expansion into argon ambient. Our results indicate that the tin ions can be effectively mitigated with a partial argon pressure ∼65mTorr. Apart from thermalization and deceleration of plume species, the addition of ambient gas leads to other events such as double peak formation in the temporal distributions and ambient plasma formation.