Morphological Control By Localized Blending in Phase Separated Block Copolymer Thin Films

Block copolymer self-assembly is a promising bottom-up route to fabricating dense periodic arrays of monodisperse nanoscale features. In recent years, block copolymer lithography in thin films has attracted great interest as a tool for nanoscale device fabrication. However, one major limitation to the use of block copolymer lithography is the difficulty in tuning equilibrium morphologies and domain size in a continuous film. Here we will present a simple layer-by-layer approach to form block copolymer blends, with varying composition across the thin film, that independently controls both the morphology and domain spacing of nanostructures. This process results in equilibrium nanostructures of diverse shapes and sizes that will ultimately reduce the number of processing steps required to fabricate nanoscale devices from self-assembled block copolymer thin films.