Fabrication of multi-bit crossbar circuits at sub-50 nm half-pitch by using UV-based nanoimprint lithography

Nanoimprinting lithography was initiated as an alternative way to achieve nanoscale structures with high throughput and low cost. We have developed a UV-nanoimprint process to fabricate 34×34 crossbar circuits at 50 nm half-pitch (equivalent to a bit density of 10 Gbit/cm²) with single-layer structure. We devised a technique that exploits the opposite free energies of the mold and substrate surfaces to produce a very uniform resist film without any trap air. As the pitch size decreases, lift-off process with single-layer structure was difficult to define metal wires. Sixty-six by sixty-six crossbar structures with a half-pitch of 30 nm (equivalent to a bit density of 30 Gbit/cm²) were produced with bi-layer structure.