Fabrication of Lithographically Defined Chemically Patterned Polymer Brushes and Mats

Abstract

Chemically patterned surfaces comprised of polymer mats and brushes of well-defined chemistry were fabricated at the length scale of 10 nm. A key concept is the integration of new materials, cross-linked polymer mats, with traditional lithographic processing. Resist was patterned on top of cross-linked polystyrene mats. After etching, regions of the remaining mat with dimensions ranging from 10 to 35 nm were separated by interspatial openings to the underlying substrate. End-grafted polymer brushes, in this case hydroxyl-terminated poly(2-vinylpyridine) or polystyrene−poly(methyl methacrylate) random copolymer, were grafted into the exposed, interspatial regions from films spin-coated over the patterned mat. Both block copolymer wetting studies, with polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA), and near-edge X-ray fine structure spectroscopy showed that with sufficient cross-linking the polymer mat chemistry was unaffected by the subsequent grafting of the polymer brush. The precise definition of both the chemistry and the geometry was demostrated with two sensitive applications of nanoscale chemical patterns: the site-specific immobilization of Au nanoparticles and the directed assembly of overlying PS-b-PMMA films.

Block Copolymer Orientation Control Using a Top-Coat Surface Treatment

“…This is but one example of many in which long range order in the BCP patterns can be achieved by directed self-assembly (DSA) techniques based on grapho-or chemical-epitaxy techniques [5][6][7][8].…”

Three Dimensional Assembly in Directed Self-assembly of Block Copolymers

“…A variety of directing strategies, such as chemoepitaxy [3,4], graphoepitaxy [5,6], and pre-patterns that combine both chemo and graphoepitaxy [7], have been demonstrated. While BCP thin films are generally addressed as 2D patterning layers, BCP are inherently three dimensional (3D) materials, and even in extremely thin film, where the film thickness is smaller than the BCP periodicity (L 0 ), 3D structures can be found [8].…”

Directed Self-Assembly Materials for High Resolution beyond PS-<i>b</i>-PMMA

“…A variety of DSA flows based on both of graphoepitaxy and chemoepitaxy have been designed to build guiding structures on which uniformly oriented block copolymer domains are formed. Especially, two major chemoepitaxy DSA processes, LiNe flow [3] and SMART™ flow [4], have been intensively investigated to verify the PSb-PMMA-based DSA technology to meet demands from the advanced technology nodes. Significant progresses in performances of DSA have been made based on the PS-b-PMMA platform in recent years.…”