Soft x-ray narrow-band laser plasma sources for nanotechnology

Abstract

The emission from laser produced plasma has been employed as a source of soft X-ray radiation for nanotechnology. By incorporating high Z elements into low Z solid hosts, targets have been fabricated which, when illuminated with high power Nd:YAG laser pulses, emit a significant proportion of the incident energy in a narrow wavelength region, with reduced continuum emission in the adjacent spectrum. Such a source would be of considerable utility in a projection lithography setup, where the presence of multilayer optics prevents the use of broadband soft X-ray sources. Cesium, barium and cerium were incorporated into different targets, resulting in different peak wavelengths for the emission. 4d - 4f transitions in highly ionized species have been identified as being responsible for the narrow emission feature. In addition, efforts to reduce particulate debris from the target are reported.