RESUMO
Extreme ultraviolet (EUV) lithography is currently entering high-volume manufacturing to enable the continued miniaturization of semiconductor devices. The required EUV light, at 13.5 nm wavelength, is produced in a hot and dense laser-driven tin plasma. The atomic origins of this light are demonstrably poorly understood. Here we calculate detailed tin opacity spectra using the Los Alamos atomic physics suite ATOMIC and validate these calculations with experimental comparisons. Our key finding is that EUV light largely originates from transitions between multiply-excited states, and not from the singly-excited states decaying to the ground state as is the current paradigm. Moreover, we find that transitions between these multiply-excited states also contribute in the same narrow window around 13.5 nm as those originating from singly-excited states, and this striking property holds over a wide range of charge states. We thus reveal the doubly magic behavior of tin and the origins of the EUV light.
RESUMO
We report on a laser system capable of generating high-energy (>270 mJ) temporally shaped pulses at 1064 nm with 0.43-ns shaping resolution. The pulses are generated by modulation of a continuous-wave seed laser and subsequent amplification by a dual-stage grazing-incidence Nd:YVO4 "bounce" amplifier and a Nd:YAG power amplifier (all quasi-continuous diode-pumped). The system produces pulses with a high-quality top-hat spatial beam profile with up to 0.6 GW of peak power and 44 W of average power, a power stability of 0.22% rms, and fully programmable complex temporal shapes.
