Local Control of Microdomain Orientation in Diblock Copolymer Thin Films with Electric Fields

TLDR

Electric fields can locally control the orientation of domains in diblock copolymer thin films, offering a route to nanostructure fabrication. Spin‑coated asymmetric PS‑b‑PMMA films with cylindrical PMMA microdomains were deposited onto silicon nitride membranes patterned with planar electrodes, enabling TEM observation of domain alignment. The cylinders aligned parallel to the electric field lines for fields exceeding 30 kV/cm after annealing at 250 °C in an inert atmosphere for 24 h.

Abstract

Local control of the domain orientation in diblock copolymer thin films can be obtained by the application of electric fields on micrometer-length scales. Thin films of an asymmetric polystyrene-polymethylmethacrylate diblock copolymer, with cylindrical polymethylmethacrylate microdomains, were spin-coated onto substrates previously patterned with planar electrodes. The substrates, 100-nanometer-thick silicon nitride membranes, allow direct observation of the electrodes and the copolymer domain structure by transmission electron microscopy. The cylinders aligned parallel to the electric field lines for fields exceeding 30 kilovolts per centimeter, after annealing at 250°C in an inert atmosphere for 24 hours. This technique could find application in nanostructure fabrication.