Manipulating the sequences of block copolymer patterns on corrugated substrates

This paper describes manipulating the sequences of cylinder-forming block copolymer patterns on corrugated substrates. Upon thermal annealing, the topographic corrugation of the substrate generates a spontaneous flow-field of the block copolymer and induces thickness-dependent microdomains. The corrugation gradient has some range of surface roughness characterized by its topographic parameters. When the substrate topography matches the dimensions of the intrinsic surface relief structures of the block copolymer, the surface roughening is suppressed by inverted terrace formation, and sequenced patterns of in-plane cylinders and nonbulk lamella phases are generated. As soon as the surface roughening forms on the corrugated substrate with a roughness parameter lower than that of the surface relief structures, the reverse sequences of the alternative microphase separated structures are developed. However, enhanced mobility of the block copolymer induced by solvent annealing suppresses the pattern sequencing and the in-plane cylinders with a relatively high degree of ordering generated over the entire surface of the corrugated substrate. This observation may further enable new approaches for manipulating the sequences of spatially registered hierarchical surface patterns of block copolymers.