Directed self-assembly of triblock copolymers for sub-10 nm nanofabrication using polymeric additives

Abstract

Directed self-assembly (DSA) of block copolymers (BCPs) is one of the most promising techniques to tackle the everincreasing demand for sub-lithographic features in semiconductor industries. BCPs with high Flory Huggins parameter (χ) are of particular interest due to their ability to self-assemble at the length scale in sub-10 nm regime. However, such high-χ BCPs typically have imbalanced surface energies between respective blocks, making it a challenge to achieve desired perpendicular orientation. To address this challenge, we mixed a polymeric additive with poly(2-vinylpyridine)- block-polystyrene-block-poly(2-vinylpyridine) (P2VP-b-PS-b-P2VP) and successfully achieved perpendicular orientation control of the triblock copolymer. The polymeric additive has lower surface energy than both PS and P2VP blocks, and it selectively interacts with high surface energy P2VP blocks via hydrogen bonding. As a result, the surface energies of PS and P2VP blocks are balanced and perpendicular orientation forms upon thermal annealing. Using this approach, we demonstrate 5X density multiplication DSA with a half pitch of 8.5 nm via chemo-epitaxy. This material system is also amenable to sequential infiltration synthesis (SIS) without the need to remove the additive, revealing its pattern transfer potential. We believe that this integration-friendly DSA approach using simple thermal annealing holds the promise of bringing high-χ BCPs to advanced nanopatterning applications.