Three-dimensional nanostructured multilayers from cross-linkable block copolymer

다국어 초록 (Multilingual Abstract)

In this work, we fabricated three dimensional nanotemplates using crosslinkable block copolymers (BCPs). We synthesized crosslinkable BCPs, P(S-r-(S-N3))-b-PMMA, in which 1.5 mol % of crosslinkable azide (N3) groups were incorporated. The block composition was controlled to have cylindrical or lamellar microdomains. First, thin films of P(S-r-(S-N3))-b-PMMA block copolymers, exhibiting either perpendicularly oriented cylinders or lamellae, were prepared on the silicon substrates that were neutralized with PS-r-PMMA random copolymers. To construct the BCP multilayers, the films were thermally crosslinked, and then cylinder- or lamellar-forming BCPs were prepared on top without disturbing the underlying layers. Interestingly, it was observed that lamellae on cylinder layers and cylinders on lamellae layers exhibit the perpendicular orientations. This may suggest that the underlying layers could neutralize the interfacial interactions as PS-r-PMMA random copolymers. We attribute such registration to the minimization of wetting energy at the interface, while the perpendicular orientation of lamellae can be also affected by other factors, such as the nematic interaction, quenching of polymer chains at the surface, the substrate roughness, etc. These results demonstrate a promising strategy for designing well-defined 3D nanotemplates for advanced BCP nanolithography.