Abstract

Soft x-ray projection lithography (SXPL) systems are designed to operate with narrow bandwidths around 130Å, where the highest reflectivity mirrors have been demonstrated¹. Several different sources are under consideration. One possibility is the laser-produced plasma, in which Intense visible laser light incident on a solid metal surface in vacuum generates an x-ray emitting plasma. An important question is whether sufficient x-ray radiation is generated at 130Å. Although much work has been performed at the very high laser intensities used in fusion applications, no experiments existed at the pulse widths and intensities necessary for SXPL systems. In this work a comprehensive soft x-ray database for laser plasma lithographic sources was developed. We determined the absolute conversion efficiency from laser light into x-rays for various target materials, laser wavelengths {1.064μm & 532nm),pulse lengths (7.5-30ns), incident intensities{1x10⁹W/cm² - 1x10¹³W/cm), and spot sizes(15μm-2mm).

© 1993 Optical Society of America