Contrôle local d'interface et du mouillage pour la nano-fabrication par auto-assemblage de copolymères à blocs – BONSAI

In microelectronics and nanoscience, geometrical scaling is still at the heart of the work and a wide range of technologies are used to further push the resolution. Directed Self Assembly (DSA) lithography is one of these and key demonstrations based on thin films of organic block copolymers (BCPs) have been made. With the advent of sub-10nm BCP systems, interface manipulations through substrate’s treatment and top-coat layers have become a critical aspect in obtaining uniform nanostructured films. Nonetheless, the interplay between self-assembly of BCPs at the nanoscale and perpendicularly oriented polymer layer wetting clearly lacks fundamental understanding, even though it is of crucial importance for controlling (thermo)dynamic stability of such films or to achieve complex nano-architectures based on local modifications of interfaces and/or wetting. BONSAI brings together 4 laboratories recognized in the field of copolymer chemistry, wetting and stability of thin films and nanolithography by self-assembly, to address these issues. To do this, we propose a systematic study of the thin film stability of a well-known copolymer, PS-b-PMMA, with respect to thermal annealing and as a function of the order-disorder transition temperature of the copolymer, in particular in the presence of a neutral layer. The identification of the dewetting mechanisms (and the possible presence of slip at the interface) will then be extended to a sub-10 nm BCP, where the role of the mechanical properties of the top-coat on the stability of the BCP will be evaluated. These results will allow a better control of the directed self-assembly of BCPs, but also to use dewetting in a controlled manner for the creation of 3D nanostructures with different morphologies.