Ultrafast Time-Resolved Pump-Probe Investigation of Nanosecond Extreme Ultraviolet-Light-Induced Damage Dynamics on BC/Ru Nano-Bilayer Film.

An ultrafast time-resolved pump-probe setup with both high temporal and spatial resolution is developed to investigate the transient interaction between a nanosecond extreme ultraviolet (EUV) pulse and matter. By using a delayed femtosecond probe pulse, the pattern evolution of surface modification induced by an EUV pump at a wavelength of 13.5 nm can be imaged at different delay times, which provides deep insight into the EUV-induced damage dynamics and damage mechanisms. As a demonstration, single-shot EUV damage on a BC(6.0 nm)/Ru(30.4 nm)/D263 nano-bilayer optical film is studied using this pump-probe method. A recoverable phenomenon is found during the evolution process of the dome-shaped damage region. This is explained by the elastic and plastic deformations resulting from the huge compressive stress difference at the Ru-substrate interface with the help of simulations on the thermal effects and mechanical responses. This damage mechanism is further proven by the complementary experiments at a higher EUV fluence at 13.5 nm.