X-ray lithography for sub-half-micrometer devices.

Steeply profiled high-aspect-ratio Ta patterns for X-ray masks have been fabricated using low-temperature ECR plasma etching with SF6 gas.Side etching of the Ta patterns was restrained without using any additional gas to form a sidewall protection polymeric film.This X-ray mask technology has been applied to sub-half-micrometer pattern fabrication using an X-ray lithography system based on a compact synchrotron.N-channel MOS transistors with 0.3-pm gates have been fabricated using the X-ray lithography for all four mask levels.