Behavior of Lamellar Forming Block Copolymers under Nanoconfinement: Implications for Topography Directed Self-Assembly of Sub-10 nm Structures

Directed self-assembly of block copolymers (BCPs) is a promising technique for the nanofabrication of structures with dimensions smaller than what can be achieved by current photolithography approaches. In particular, there has been significant interest in the development of BCPs that can achieve ever smaller feature sizes with low levels of defects. Here we investigate the directed self-assembly of a high-chi BCP, polystyrene-block-poly(in-lactide), which is capable of producing structures with dimensions less than 10 nm. In addition, we study the behavior of the BCP under nanoconfinement and the ability of the polymer chains to compress and stretch in response to the geometry of the confining volume. Key findings of this study are that the level of defects in the self-assembled structures are strongly related to the relative interfacial interactions of the BCP as well as the degree of frustration of the polymer chains under nanoconfinement relative to the bulk. These results have particular significance for nanofabrication of ordered structures, which is of relevance for the fabrication of nanowires, metamaterials, and next-generation computer chips.