Characterization and optimization of the laser-produced plasma EUV source at 13.5 nm based on a double-stream Xe/He gas puff target

Abstract

The paper describes a debris-free, efficient laserproduced plasma source emitting EUV radiation. The source is based on a double-stream Xe/He gas-puff. Its properties and spectroscopic signatures are characterized and discussed. The spatio-spectral features of the EUV emission are investigated. We show a large body of results related to the intensity and brightness of the EUV emission, its spatial, temporal, and angular behavior and the effect of the repetition rate as well. A conversion efficiency of laser energy into EUV in-band energy at 13.5 nm of 0.42% has been gained. The electron temperature and electron density of the source were estimated by means of a novel method using the FLY code. The experimental data and the Hullac code calculations are compared and discussed. The source is well suited for EUV metrology purposes. The potential of the source for R. Rakowski ( ) ·

Radiation characteristics of extreme UV and soft X-ray sources

“…Contrarily, gaseous targets are almost free from debris [18]. Short gas pulses with durations of µs .…”

“…Typically, the target gas is expanded into a vacuum environment and the density drops rapidly in all directions. In order to weaken this density loss, there exist strategies to laterally guide the target gas by a concentric jet [18]. Ideally, here another atomic species is employed which shows weak absorption of the generated soft x-rays such as, for example, helium.…”

Spatial coherence measurements of the EUV emission from laser-plasma source based on xenon/helium gas puff target

“…Such plasma emits radiation in the broad range of wavelengths, from soft X-rays to infrared, depending on the gas used as a target, laser beam properties, and parameters of the focusing system. In this experiment, an efficient extreme ultraviolet emission was achieved from xenon gas, as already reported in [16].…”

Next generation nanolithography based on Ru/Be and Rh/Sr multilayer optics

“…5, the efficiency in the short wavelength range can be significantly increased. 19,22 In contrast with 13.5 nm, there is no precise data on the conversion efficiency of Xe sources at 11 nm in the literature, however, some estimates are given. In particular, in Ref.…”

“…The measured intensity of the radiation in the region of 11 nm is 4-5 times higher than at 13.5 nm. 19,[22][23][24][25] Calculated spectra of Xe plasmas with different temperatures and electron densities have been reported in. 26 They show that the position of the spectral maxima and the ratio of the radiation intensities at 11 nm and 13.5 nm vary.…”