Ultra high density nanopore arrays using self assembled diblock copolymer

In the present work, processing conditions for high density nanoporous templates using self assembled morphology of asymmetric diblock copolymers with pore lengths stretching the entire thickness of the polymer films are investigated. Poly styrene (PS) and poly methylmethacrylate (PMMA) are used as polymer blocks for fabrication of diblock copolymer film. Polymer solution of 1% (w/w) in toluene was spin coated on gold coated silicon substrate to obtain polymer film of varied thickness ranging from 72.4 nm to 2631.57 nm. Upon annealing the film under the influence of electric field and etching by UV radiation followed by rinsing in sonicated acetic acid, highly dense hexagonally ordered pores perpendicular to the substrate over the entire film thickness with average pore diameters from 13.7 nm onwards were obtained. The spin speed and polymer concentration account for thickness of the film, while the molecular weights of the polymer blocks, annealing time and etching time determine the pore formation and density in the resulting template. The resulting ultrahigh density nanoporous templates were used for growth of Co nanowires using electrodeposition in three electrode configuration. The morphological features of the polymer film, nanoporous template and the nanowires were investigated using SEM and AFM techniques. Figs.1a&1b are SEM images of different pore density templates resulting from different annealing procedures in which nanowires were grown.