Mold-assisted near-field optical lithography

We describe a new approach of mold-assisted lithography based on photopolymerization under near-field regime. In addition to a numerical analysis, we also present the mold fabrication and the replication of sub-100 nm features. The molds were fabricated by electron beam lithography and reactive ion etching of a fused silica substrate covered by a thin film absorber cap layer. Exposures were done after gently pressing the mold into a light curable monomer film. Because of the mold and near-field optical confinements, the resulted organic layer provides not only a thickness contrast but also a material composition contrast, i.e., polymer in unmasked area and monomer in masked parts.