Graphoepitaxy of Symmetric Six‐Arm Star‐Shaped Poly(methyl methacrylate)‐block‐Polystyrene Copolymer Thin Film

Abstract

The authors perform directed self-assembly based on graphoepitaxy of symmetric six-arm star-shaped poly(methyl methacrylate)-block-polystyrene copolymer [(PMMA-b-PS) 6 ] thin film. The affinity between each block and the trench wall is adjusted by using polymer brushes or selective gold (Au) deposition. When the surface of the trench is strongly selective for the PMMA block, (n+0.75)L 0 thick (n is the number of the lamellae, L 0 is lamellar domain spacing) lamellae parallel to the trench wall are formed at each side, while nanotubes are formed away from the trench wall. However, for a trench grafted with PS brushes, nanotubes are formed beside (n+0.25)L 0 thick lamellar layers. By adjusting the trench width (W) and the affinity between the block and the wall, various dual nanopatterns consisting of lines and nanotubes are fabricated. Moreover, when the trench wall is selectively deposited by Au, asymmetric dual nanopattern is formed, where different numbers of lines exist on each side wall, while nanotubes are formed in the middle of the trench. The observed morphologies depending on the commensurability condition between W and L 0 are consistent with predictions by self-consistent field theory.

WiFi-like Nanostructures from Confinement of Block Copolymer Microdomains in Asymmetric Hemisphere Nanocavity

“…Then, alternating PS and PMMA microdomains making concentric rings are formed to satisfy the commensurability between L 0 and D . On the other hand, the gold layer prefers PS chains compared with PMMA chains. − Thus, PS microdomains should be located at the gold surface, and subsequently, alternating PMMA and PS microdomains are formed. For t Au = ( n + 0.5) L 0 (here, n is an integer), at the center of the nanocavity, even PS microdomains on the gold surface (with a thickness of 0.5 L 0 ) at the left side of the nanocavity are smoothly connected to other PS microdomains (with a thickness of 1 L 0 ) emerging from the concentric ring patterns at the right side of the nanocavity.…”