Potential of discharge-based lithium plasma as an extreme ultraviolet source

Abstract

Extreme ultraviolet (EUV) discharge-based lamps for EUV lithography need to generate extremely high power in the spectrum band of 13.5±0.135nm. A model was developed to investigate the wavelength-integrated Lyman-α lines light outputs in hydrogen-like lithium ion. The analysis reveals that the commonly observed low conversion efficiency is largely due to a transient nature of Z discharge-based plasma and that a magnetically confined lithium plasma is an efficient EUV source even at low electron temperature. Calculation shows necessary confinement time that raises the conversion efficiency up to half the spectral efficiency.