Fabrication of x-ray masks using evaporated electron sensitive layers for back patterning of membranes

Abstract

A process aimed at fabricating proximity x-ray lithography masks is presented. In this technique, the Ta absorber layer is deposited and patterned on the back side of the membrane and nonspin-coated electron sensitive layers were used in order to achieve high resolution patterning of this absorber. The advantages gained by this approach include a reduction of the membrane temperature during the plasma etching step of the absorber patterns without using any cooling gas. This temperature reduction results from the direct contact of the membrane with a cooling plate. This approach also allows increased protection of the absorber patterns from contamination during exposure of the mask. A third advantage is that the smooth surface of the mask exposed to the wafer in the x-ray lithography stepper may also make it possible to reduce the gap between wafer and mask, thus achieving increased resolution with the x-ray lithography process.