13.5 nm emission from composite targets containing tin

Abstract

The aim of this study is to investigate ways to maximise the efficiency of tin based laser produced plasmas as sources of EUV radiation in the 2% band centered on 13.5 nm. It has been found that targets containing below 15% tin atoms by number emit more brightly in the spectral region around 13.5 nm than pure tin targets. Furthermore, if the remaining material in the target is composed on primarily low-Z atoms, then both plasma continuum radiation and Bremsstrahlung radiation are greatly reduced. In addition, if the target is illuminated with a prepulse, the conversion efficiency shows a distinct increase. The third parameter under examination is the laser power density, which controls the ion distribution in the plasma. The influence of low-Z atoms on the tin ion distribution in the plasma has been investigated and found to be of little consequence. Measurements were made in the region from 9 -17 nm on an absolutely calibrated 0.25-m flat field grazing incidence spectrograph, and on two 2-m grazing incidence spectrographs. Spectra and conversion efficiency data from a range of target materials and illumination regimes are presented.

EUV generation using a droplet of a suspension including tin as a target of a high-efficiency LPP source for high volume production

“…They found 5 % target showed the highest efficiency higher than a Sn plate [23]. Our present result agrees with their report.…”

(TMT)n clusters as dilute debris‐free tin source for generation of multiply charged tin ions of relevance in extreme ultraviolet (EUV) lithography, under intense laser irradiation

“…Numerically, it has been shown that there is no significant change in the tin ion distribution when the target concentration of tin was reduced from 100% to 1% . Also, studies carried out by Hayden et al and Harilal et al suggest that dilute tin targets (15% and 0.5%) radiate more brightly in the EUV region at ~13.5 nm than dense (bulk) tin targets. Thus, efforts are currently being made to maximize the efficiency of EUV emission from tin‐doped targets, along with minimization of the tin concentration in the target matrix.…”

Spectral and ion emission features of laser-produced Sn and SnO2plasmas

“…[12,13] To obtain a higher CE, researchers have come up with new ideas for the Sn target. Hayden et al [14] used ceramic slab targets doped with 5% and 6% Sn and an Nd:YAG laser for the EUV source. The results showed that the 5% (i.e., low density) Sn doped ceramic target had a maximum EUV CE of over 2.5% at the laser pulse intensity of 1.91 ×10 11 W•cm −2 , but the EUV CE of the Sn doped target was not always higher than that of pure Sn, because the EUV CE also varied with the laser power density.…”