Plasma-induced damage of multilayer coatings in EUVL

A Particle-in-Cell Monte Carlo model is used to simulate extreme ultraviolet driven plasma. In an extreme ultraviolet lithography tool, photons of a pulsed discharge source will ionize a low pressure argon gas by photoionization. Together with the photoelectric effect, this results in a strongly time dependent and low density plasma, which is potentially dangerous to the optical elements, the collector in particular. Plasma sheaths will develop and ions are accelerated towards the collector, which might lead to sputtering. A spherical geometry is used to study the plasma between the point source and collector. Simulations are performed to study the in.uence of background pressure and source intensity on the damage to the collector by sputtering.