Controlling Orientation and Defects in Block Copolymer Thin Films Through Directed Self-Assembly

摘要

We use surface energy and film thickness gradients to map the surface defect formation in thin films of symmetric lamellar diblock copolymer films of poly(styrene-block-methylmethacrylate) as a function of film thickness and substrate surface energy. The film surface patterns were found to change as a function of surface energy. The nature of these surface patterns indicated that there were regions of asymmetric and symmetric wetting separated by a neutral zone of finite width. A closer examination of the film morphology in the neutral region indicates that they are topographically smooth regardless of film thickness, suggesting vertical ordering of lamellae, which is desirable for many nanotechnology applications. Atomic force microscopy and small angle neutron scattering confirm these preliminary observations.