(166p) Improving the Pattern Transfer Process Using AAO Templates on Hydrophobic Substrates

Periodic nanopore array patterning of surfaces has received enormous attention in recent years due to its unique and enhanced optical, electrical and transport properties. Nanopatterning surfaces by template assisted pattern transfer technique provides a cost- effective and large throughput approach than e-beam lithography and nanoimprinting lithography techniques. Anodized Aluminum Oxide is a popular nanomaterial used as a mask in template assisted pattern transfer techniques for fabricating nanopores, nanowires, nanodots etc. It is self-organized nanostructured material with high aspect ratio structure, and hexagonally ordered straight nanopore channels. In template assisted fabrication using AAO, there are two ways of contacting the AAO mask on the substrate of interest: the AAO can be directly grown on evaporated/sputtered Aluminum layer on the substrate or by transferring a free standing AAO membrane grown separately on a thick aluminum sheet to the substrate of interest. The second approach is usually preferred due to its high pore density and template quality. Through this approach, nanopore arrays have been fabricated on various hydrophilic substrates like Si, GaAs, InP, GaN and ZnTe etc. However, when this process is performed on hydrophobic polymers with low surface energy, the template transfer is limited to smaller areas due to poor contact between the AAO membrane and the substrate. Apart from this, other factors like improper removal of the polymer support layer due to polymer solution wetting the pore channels, and incomplete barrier layer removal due to non-uniform barrier layer thickness across the AAO template limits the pattern transfer area to few hundreds of µm². In this work, the factors affecting the pattern transfer process on Teflon using AAO templates were identified, and a modified processing technique is carried out to improve the pattern transfer process. By applying the modified procedure, we were able to achieve pattern transfer over a large areas of inch² on Teflon.