The ever-increasing demand for powerful computing and next-generation devices necessitates innovative lithographic solutions for increasing the number density and complexity of patternable features for use in integrated circuits. Block Copolymer (BCP) self-assembly in thin films offers a promising alternative for patterning sub-10 nm 2-dimensional and 3- dimensional features in the sub-optical lithographic resolution with reduced complexity. Traditionally, BCP alignment for patterning has been achieved using lithographically defined templates. However, the template-free alignment of BCPs for sub-10 nm patterning has not been achieved to date despite the research efforts for the past 2 decades. In this work, we show the template-free alignment of lamellar BCPs for sub-10 nm patterning and generating hybrid nanostructures over large areas. We use thermal shear stress generated by a conformal elastomer during the thermal gradient-based annealing for the self-assembly and the alignment of the vertically oriented lamellar BCPs confined between neutral substrate and topcoat. Furthermore, we use these aligned BCP templates to generate large area aligned gold nanowires having tunable dimensions by a solution-phase infiltration method and BCP template removal. Additionally, we extend the use of shear alignment of BCPs to atom transfer radical polymerization (ATRP) synthesized polymer grafted nanoparticles (PGNPs) and BCP blends. The PGNPs get localized to one of the BCP domains during shear alignment, resulting in aligned nanoparticle strings along the shear direction. We demonstrate the use of the aligned PGNP-BCP blends to generate hybrid metallic nanowire-dielectric nanoparticle structure with precise placement, by converting one of the BCP domains to gold nanowires and etching the organic materials. These hybrid nanostructures show distinct plasmonic resonance with a shift of peak intensity of 15 nm as compared to neat gold nanowires. These findings open avenues to design novel nanostructures having applications in nanopatterning, electronics, optical and magnetic materials.

Template-free alignment of lamellar block copolymers for large area sub-10 nm patterning and hybrid nanostructures

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.