Deep plasmonic direct writing lithography with ENZ metamaterials and nanoantenna

In this article, we demonstrate a specially designed resonant metamaterial with epsilon-near-zero (ENZ) and nanoantenna to enhance the exposure depth in plasmonic direct writing lithography more than 10 times. The ENZ metamaterial composed of a Ag/Si3N4 multilayer thin film, converts the evanescent field generated by the bowtie aperture nanoantenna to propagating waves with low divergence and high collimation. Deep sub-diffraction limited resolution of less than 65 nm (λ/7) with exposure depth greater than 100 nm is achieved. This work brings plasmonic direct writing lithography one step closer to practical applicaitons.