From Nanorings to Nanodots by Patterning with Block Copolymers

Complex fabrication procedures are required to produce thin films containing highly ordered, nanoscale metal dot/rod/ring patterns, or substrate layers containing nanosized pore, pillar or ring patterns for applications in data storage, electronics, optoelectronics, molecular separation, etc. It is also technically difficult to produce nanoscale ring patterns with <100 nm in outer-ring diameter within or above a substrate layer over a relatively large substrate area (~ 1 inch x 1 inch).

Russell et al. have recently developed a simple, efficient and economical process to produce metal-coated nanoporous templates as high-aspect ratio etching masks. This patterning process creates nanopores in a block copolymer thin film by using simple surface reconstruction to dissolve and dry the minor block component of the block copolymer, thus eliminating the use of complex procedures or harsh conditions to remove the minor block.

Nanopattemed surfaces are prepared by a method that includes forming a block copolymer film on a substrate, annealing and surface reconstructing the block copolymer film to create an array of cylindrical voids, depositing a metal on the surface-reconstructed block copolymer film, and heating the metal-coated block copolymer film to redistribute at least some of the metal into the cylindrical voids. When very thin metal layers and low heating temperatures are used, metal nanodots can be formed. When thicker metal layers and higher heating temperatures are used, the resulting metal structure includes nanoring-shaped voids. The nano-pattemed surfaces can be transferred to the underlying substrates via
etching, or used to prepare nanodot- or nanoring-decorated substrate surfaces.