Characterization of nano-arrays fabricated via self-assembly of block copolymers

Abstract

This research focused on methods for regulating arrangement of self-assembled block copolymers by understanding fabrication conditions and their effects on the polymers on flat and patterned substrates. Block copolymer self-assembly is a simple and low cost process for creating lithographic masks with features under 100nm in dimension. These patterns can be transferred to more permanent materials for applications in electronics, magnetic devices, as well as sensors and filters. Polystyrene-poly(ferrocenyldimethylsilane) block copolymer thin films were characterized in terms of their spin curves, PSF spherical domain cross sectional area distributions, and correlation distances. Optimal fabrication conditions were selected from studying polymer behavior on flat substrates and then used for templated substrate studies. Substrates that were templated with grooves produced quantized numbers of rows of spherical domains ranging from 4 to 7. Behavior in these grooves was characterized in terms of groove width constraints, cross sectional domain area distributions, and row ordering. For all templated arrays, the lengths of ordered regions were more than 2 fold higher than the diameters of ordered regions of arrays on flat substrates. The characterization accomplished in this work will be used to compare block copolymers with similar volume fractions of the blocks that allow sphere microdomain formation but of different molecular weights. The ultimate goals are to establish how the molecular weight of this block copolymer affects its self assembly on templated and on flat substrates and to use this factor as well as fabrication conditions and template geometries to engineer arrays with desirable properties.