CHARACTERIZATION AND CONTROL OF LASER-PLASMA FLUX PARAMETERS FOR SOFT-X-RAY PROJECTION LITHOGRAPHY

Laser plasmas are intrinsically an attractive soft-x-ray source for pr ojection lithography. Compact, flexible, and small enough to be dedica ted to a single installation, they offer an alternative to costly mult i-installation synchrotron sources. For laser plasmas to provide ideal sources of soft x rays for projection lithography, their properties m ust be tuned to optimize several critical parameters. High x-ray conve rsion in the spectral band relevant to projection hthography is obviou sly required and has already received the attention of several studies . However, other features, such as the spectral content and direction of the x-ray emission, the plasma and particulate emission, the techno logy of the target, and efficient laser design, must also be optimized . No systematic study of all these features specifically for projectio n hthography has yet been made. It is our purpose to optimize these pa rameters in a coordinated approach, which leads to the design of a sou rce that satisfies all the demanding requirements of an operating lith ographic installation. We make an initial investigation of the plasma and particle emission of plasmas that have previously been shown to be good x-ray converters to the 13-nm band. The importance of the result s reported may well force new approaches to the design of laser plasma soft-x-ray sources for projection lithography.