Xe laser-plasma EUV radiation source with a wavelength near 11 nm—Optimization and conversion efficiency

Abstract

Xe laser-produced plasma with a gas-jet target is considered a promising λ = 11.2-nm radiation source for a possible extension of the EUV (Extreme UltraViolet) lithography. EUV spectra of the plasma radiation obtained with the aid of both a grating spectrograph and Bragg mirrors are presented. The absorption of the EUV radiation in the cold peripheral gas has been eliminated in another experiment by means of irradiating the target with a wide defocused laser beam that resulted in an increase of the EUV output by an order of magnitude. In that experiment, the conversion efficiency at λ = 11.2 nm amounted to 3.9%.