Contrast amplification of very high resolution x-ray masks

Abstract
Future applications of synchrotron based proximity x-ray lithography will require cost effective methods to generate high density patterns with features smaller than 0.25 μ. Masks written with e-beam lithography typically use a trilayer resist system. The process is complicated, defect prone, and expensive, but result in a high contrast proximity x-ray mask. We are investigating an alternative technique involving the e-beam patterning of nanostructure features into a single layer of resist, and its direct metallization to produce a low contrast x-ray mask. This would be used as a master mask for making duplicates. This paper investigates methods that varied spectral and developmental parameters to heighten the contrast sufficiently for pattern transfer into thicker resist providing a potential contrast increase from a dose contrast of 1.7 to on the order of 10.