Controlled Spacing between Nanopatterned Regions in Block Copolymer Films Obtained by Utilizing Substrate Topography for Local Film Thickness Differentiation

Abstract

Various types of devices require hierarchically nanopatterned substrates, where the spacing between patterned domains is controlled. Ultraconfined films exhibit extreme morphological sensitivity to slight variations in film thickness when the substrate is highly selective toward one of the blocks. Here, it is shown that using the substrate's topography as a thickness differentiating tool enables the creation of domains with different surface patterns in a fully controlled fashion from a single, unblended block copolymer. This approach is applicable to block copolymers of different compositions and to different topographical patterns and thus opens numerous possibilities for the hierarchical construction of multifunctional devices.

Multifunctional Structured Platforms: From Patterning of Polymer-Based Films to Their Subsequent Filling with Various Nanomaterials

“…As we have observed above, the two most common patterning methodologies, topdown and bottom-up, lead each to the fabrication of a huge diversity of periodic surface relief patterns of different material nature and functionalities. Nonetheless, in order to fabricate novel and rather unique patterns of very specific dimensions [219,266,267] over a large area [223,266], as required by many state-of-the-art applications that include optical nanoresonators [268], nanoelectronic elements [269], bioreceptors [21], transistors [270], and others [271][272][273], it is necessary to further combine top-down and bottomup methodologies [28,205,268,269,274,275]. As a result, peculiar surface relief patterns down to the 10 nm scale [219,266,267] can be obtained through combinations of BCPL with NIL [28,205,268,269,275,276], of BCPL with EBL [270,273,277,278], of BCPL with photolithography [223,266,272], of DNA self-assembly with IBL [21], etc.…”

Solvent Vapor Annealing, Defect Analysis, and Optimization of Self-Assembly of Block Copolymers Using Machine Learning Approaches

“…9 To achieve the desired nanopattern via self-assembly, not only are the annealing parameters critical, but the initial thickness of the applied BCP monolayer must be precise, typically within one or two nanometers. 11,[63][64][65][66][67][68] The ideal thickness for a given BCP is unique, and depends upon the composition of the BCP and factors such as surface functionalization and energy, the use of a topcoat and other factors. 8,10,42,62,64,69 Both experimental and computational results strongly link initial film thickness with the resulting self-assembled structure and persistent defects.…”

“…40,71 Periodicity of structures formed from self-assembled BCP nanopatterns may be dependent upon film thickness and other processing parameters, as has been recently shown with bottlebrush BCPs. 63,72 The defects observed in self-assembled monolayers of BCPs that form hexagonal dot patterns are dominated by disclinations and dislocations, as well as point defects along grain boundaries between uncorrelated domains, multilayers, and the presence of lamellae. [73][74][75][76][77] These hexagonal dot-based nanopatterns are of interest for memory materials and devices, applications that are more tolerant of defects than linear patterns for CMOS (e.g.…”

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

“…[14][15][16][17][18][19] However, only a single nanopattern (either sphere, cylinder, or lamella) is expected on a substrate, depending on the volume fraction of the blocks at a given BCP. [20] Some research groups obtained diverse nanopatterns on a single substrate by controlling the microdomain orientation of the BCPs [21][22][23][24] or employing complex molecular architecture of BCPs. [25][26][27][28][29][30][31] Also, to obtain a long-range ordering of BCP microdomains on a substrate, the BCP self-assembly is combined with geometrical confinement, so-called graphoepitaxy, which is referred to as the directed self-assembly (DSA).…”

“…[25][26][27][28][29][30][31] Also, to obtain a long-range ordering of BCP microdomains on a substrate, the BCP self-assembly is combined with geometrical confinement, so-called graphoepitaxy, which is referred to as the directed self-assembly (DSA). [21,22,[32][33][34][35][36][37][38] Confinement of the BCPs can allow the control of the orientation of microdomains by adjusting the affinity between walls and blocks. [37][38][39][40][41][42] Nealey and co-workers showed a distinct change in the orientation of lamellae or cylinders by changing the affinity between the blocks and the bottom and (or) the side wall of a trench.…”