6 nm half-pitch lines and 0.04 μm2 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 mu m(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/Al0.7Ga0.3As superlattice grown on GaAs with molecular beam epitaxy, and selectively etching away the Al0.7Ga0.3As layers in dilute hydrofluoric acid. The mould for the 0.04 mu m(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.