Theoretical simulation of extreme UV radiation source for lithography

A possible design window for extreme ultraviolet (EUV) radiation source has been introduced, which is needed for its realistic use for next generation lithography. For this goal, we have prepared a set of numerical simulation codes to estimate the conversion efficiency from laser energy to radiation energy with a wavelength of 13.5 nm with 2 % bandwidth, which includes atomic structure, opacity and emissibity and hydro dynamics codes. The simulation explains well the observed conversion efficiency dependence of incident power using GEKKO XII laser system as well as spectral shapes. It is found that the conversion efficiency into 13.5 nm at 2% bandwidth has its maximum of a few percent at the laser intensity 1-2 x 1011 W/cm2.