Sub‐5 nm Dendrimer Directed Self‐Assembly with Large‐Area Uniform Alignment by Graphoepitaxy

Abstract

Directed self-assembly (DSA) using soft materials is an important method for producing periodic nanostructures because it is a simple, cost-effective process for fabricating high-resolution patterns. Most of the previously reported DSA methods exploit the self-assembly of block copolymers, which generates a wide range of nanostructures. In this study, cylinders obtained from supramolecular dendrimer films with a high resolution (<5 nm) exhibit planar ordering over a macroscopic area via guiding topographical templates with a high aspect ratio (>10) and high spatial resolution (≈20 nm) of guiding line patterns. Theoretical and experimental studies reveal that this property is related to geometrical anchoring on the meniscus region and physical surface anchoring on the sidewall. Furthermore, this DSA of dendrimer cylinders is demonstrated by the non-regular geometry of the patterned template. The macroscopic planar alignment of the dendrimer nanostructure reveals an extremely small feature size (≈4.7 nm) on the wafer scale (>16 cm 2 ). This study is expected to open avenues for the production of a large family of supramolecular dendrimers with different phases and feature dimensions oriented by the DSA approach.

Recent Progress in Simple and Cost‐Effective Top‐Down Lithography for ≈10 nm Scale Nanopatterns: From Edge Lithography to Secondary Sputtering Lithography

“…Reproduced with permission. [199] Copyright 2019, Wiley-VCH. c) Monodispersed nanoparticle encapsulated by gold sidewall structure.…”

“…Recently, studies have been conducted to orient the tapered-shape dendrimer (propyl 3,4,5-tris (3,4,5-tris (4-(dodecyloxy) benzyloxy) benzyloxy) benzoate), a supramolecule with liquid crystal properties, into a line pattern made by SSL (Figure 16b). [199] Although no studies have been oriented in a direction parallel to the pattern direction, for the first time, this research succeeded in orienting the 4.75 nm sized dendrimer in the same direction as the pattern. In the future, if a patterning technique based on a dendrimer is developed, it may be possible to implement a large-area dendrimer pattern through such an orientation technique.…”

Wafer-Scale Unidirectional Alignment of Supramolecular Columns on Faceted Surfaces

“…In general, supramolecular columns favor homeotropic orientations on the solid-to-solid interface, 28,29 and this orientation behavior has been observed in other topographic confinement applications, such as in rectangular microchannels and sandwich systems. 11,12,14,30 Thus, it is expected that the triangular grooves should serve as a topographical confinement feature to trigger the orthogonal alignment of supramolecular columns relative to the facet surface. In addition, the triangular grooves impose severe packing constraints on the columns near the boundary of the facets.…”

“…Figure a illustrates the overall process for aligning the supramolecular columns on a faceted sapphire surface. We synthesized supramolecular columns consisting of taper-shaped molecules (Figure b), and these molecules self-assembled to form a stable columnar phase at room temperature after cooling from the isotropic temperature (87 °C). ,,, These taper-shaped molecules with long aliphatic tail groups can easily be spin-cast to form a thin-film geometry without any surface modifications.…”

“…Along with judicious control of the surface chemistry at an arbitrary substrate surface via sputtering, a self-assembled monolayer, or polymer coating, homeotropic or planar orientation of nanopatterned structures has been observed depending on the desired interfacial interaction. − While surface topographical structures also influence the orientation of supramolecular structures, homeotropic orientation has been previously generated using a top-coat process that induces geometrical confinement effects. By contrast, unidirectional planar orientation has also been achieved using topographical guiding patterns. − Because of diamagnetic anisotropy, the application of external fields, such as magnetic fields, can be used to successfully orient supramolecular structures perpendicular to the field direction . Additionally, an electric field can orient supramolecular structures parallel to the field direction, as a result of the ferroelectric response in the supramolecular architectures. , Unfortunately, despite the accumulation of research in this field, the large-scale control of orientation of supramolecular structures at the wafer scale has not yet been extensively performed.…”