Fabrication of a 34 × 34 Crossbar Structure at 50 nm Half-pitch by UV-based Nanoimprint Lithography

We have developed a single-layer UV-nanoimprint process, which was utilized to fabricate 34 × 34 crossbar circuits with a half-pitch of 50 nm (equivalent to a bit density of 10 Gbit/cm 2 ). This process contains two innovative ideas to overcome challenges in the nanoimprint at shrinking dimensions. First, our new liquid resist formulation allowed us to minimize the residual resist layer thickness after curing and requires the relatively low imprint pressure of 20 psi. Second, by engineering the surface energy of the substrate we also eliminated the problem of trapped air during contact with the mold such that it spreads the resist and expels trapped air uniformly. Our overall process required fewer processing steps than any bilayer process and yielded high quality results at 50 nm half-pitch.