6 nm half-pitch lines and 0.04 νm ² static random access memory patterns by nanoimprint lithography

A key issue in nanoimprint lithography (NIL) is determining the ultimate pitch resolution achievable for various pattern shapes and their critical dimensional control. To this end, we demonstrated the fabrication of 6 nm half-pitch gratings and 0.04 νm ² cell area SRAM metal interconnects with 20 nm line half-pitch in resist by NIL. The mould for the 6 nm half-pitch grating was fabricated by cleaving a GaAs /Al _0.7Ga _0.3As superlattice grown on GaAs with molecular beam epitaxy, and selectively etching away the Al _0.7Ga _0.3As layers in dilute hydrofluoric acid. The mould for the 0.04 νm ² SRAM metal interconnects was fabricated in silicon dioxide using 35 kV electron beam lithography with polystyrene as a negative resist and a reactive ion etch with the resist as mask. Imprints from both moulds showed excellent fidelity and critical dimension control.