Large-Scale Transfer of Anodic Aluminum Oxide Honeycomb Patterns onto Low-Surface-Energy Polymers

Nanopatterned surfaces can enhance the optical, transport, and electronic properties of a material. Patterning Teflon surfaces is attractive due to their versatility and chemical compatibility with most fluids used in industry. Using anodized aluminum oxide (AAO) as a plasma etch mask, nanopore arrays have been fabricated on various hydrophilic/high-surface-energy substrates like Si. However, when this process is replicated on low-surface-energy polymers, such as Teflon, problems that exist for all transfer techniques get amplified because of the higher reactivity of the substrate to RIE, limiting the pattern transfer to smaller areas. These challenges include a nonuniform barrier layer that leads to different breakthrough times with both wet and dry etch techniques, wetting of the nanopores with the supporting polymer, and conformal contact between the template and substrate. In this work, we mitigated the issues affecting the pattern transfer process from nanoporous AAO to Teflon and devised a technique to improve the pattern transfer process applicable to any substrate. A key step is the synchronous breakdown of the barrier layer using a two-step approach that focuses on the different material properties associated with the compact and soft regions of the barrier layer. This procedure increased the pattern transfer area on Teflon from a few hundred mu m(2) to large areas of over 5 cm(2).