Fabrication of trench nanostructures for extreme ultraviolet lithography masks by atomic force microscope lithography

Abstract

We describe methods to fabricate extreme ultraviolet lithography (EUVL) absorber mask patterns by atomic force microscope (AFM) lithography and inductively coupled plasma (ICP) etching. AFM lithography, based on anodization and cross-linking polymer resist, was applied to fabricate trench structures using only Ta and Cr/Ta bilayers. In particular, the top Cr layer was used not only as a hard mask to etch the underlying Ta in dry-etching, but also as an absorber material together with Ta. The Cr oxide or Ta with respect to Cr was eliminated due to the clear etch-selectivity of ICP dry-etching using C4F8 gas. This is a simple fabrication technique using AFM lithography fabricated metal trenches for the production of isolated metal structures as well as for producing EUVL absorber patterns.