This paper provides an overview of directed self-assembly (DSA) options that exhibit potential for enabling extensible high-volume patterning of nanoelectronics devices. It describes the current set of research requirements, which a DSA technology must satisfy to warrant insertion consideration, and summarizes the state-of-the art. The primary focus is on chemical patterning and graphoepitaxial approaches to directing block copolymer (BCP) based assembly. These options exhibit the nearest-term potential, among the emerging DSA technologies, for satisfying projected International Technology Roadmap for Semiconductors (ITRS) patterning requirements. The paper concludes with a selected set of additional challenges, which represent potential barriers to the integration of directed BCP patterning into a nanoelectronics manufacturing line, as well as a few emerging application opportunities for related functional materials. A glossary of acronyms and terms may be found at the end of this manuscript.

Controlled bottom-up assembly of nanocylinders (e.g., nanotubes, nanorods, nanowires) into large area aligned arrays is widely recognized as a key obstacle impeding application development. Processing of lyotropic liquid crystal phases is a promising route for overcoming this obstacle, but nanocylinder liquid crystalline science is a nascent field that tends to be fractionated based on material type. This review explores the common challenges and achievements of nanocylinder liquid crystal research by focusing on three types of systems: (i) carbon nanotubes, (ii) inorganic nanocylinders, and (iii) cellulose nanocrystals.

Five lipids were self-assembled in aqueous dispersions into high axial ratio nanostructures. Thermal analysis was conducted on a glycolipid self-assembled into nanotubes, previously developed by Kamiya et al. [S. Kamiya, H. Minamikawa, J-H. Jung, B. Yang, M. Masuda, and T. Shimizu, Langmuir 21, 743 (2005)], showing a dry melting onset of 148.2 °C and evidence of a highly ordered supramolecular structure. A novel hybrid structure of the glycolipid nanotubes decorated with silver nanoparticles was created. The self-assembly of four new amphiphiles, with serine and glutamic acid head groups attached to vaccenic acid and diacetylenic hydrophobic tails, was also investigated. The morphologies of these aggregates included high axial ratio nanostructures, such as nanotubes; and flat, twisted, and helical ribbons. The supramolecular aggregates of the five lipids reflect aspects of the molecular structure, such as chirality, providing evidence that such organized aggregates can be created by a rational approach to molecular design.

Reliable and cost-effective techniques to process surface nanoscale metallic structures with controllable and complex nanomorphologies is important toward progress in technologies related to sensing, energy harvesting, information storage, and computing. Here we discuss how pulsed laser melting and the ensuing self-organization by dewetting of ultrathin films can be utilized to fabricate various nanomorphologies in a predictable manner. Ultrathin metal films (1–100 nm) on inert substrates like SiO2 are generally unstable, with their free energy resembling that of a spinodal system. The energy rate theory of self-organization, which is based on balancing the rate of thermodynamic free energy change to the rate of energy dissipation, predicts the appearance of characteristic length scales. This is borne out in experiments of nanosecond pulsed laser melting of a variety of metal films. We review this laser-based self-organization technique with various examples from the behavior of Ag and Co metals on SiO2 substrates. Specifically, film thickness and film roughness can be used to control dewetting length scales, whereas knowledge of the intermolecular forces responsible for the free energy of the system control the type of morphology. Furthermore, novel dewetting is observed that is attributable to nanoscale heating effects resulting from the thickness-dependent pulsed laser heating. These results help elucidate the basic mechanisms of pulsed laser induced dewetting of metal films, but they also provide potential routes for cost-effective nanomanufacturing of metallic surfaces for applications in sensing, energy harvesting, and information processing.

Alternating current (AC) electric fields generated by coplanar electrodes are used to externally direct the assembly of submicrometer sized disk-shaped zeolite particles. At the edge of the electrode, zeolite particles assemble in a brushlike structure that forms because of an interplay between an induced dipolar interaction and the drag force due to AC electroosmotic flow. Far from the electrode edge, where the fluid is quiescent, the disk-shaped particles form a nearly hexagonally close-packed structure, similar to suspensions of spherical particles. These results demonstrate a surprising generality of field-directed structures and offer promise for a hierarchical fabrication of nanostructures from zeolites.

The self-assembling properties of two rationally designed discotic π-conjugated hexaazatrinaphthylene (HATNA) molecules have been studied. In appropriate solvent systems, both ester-dodecyl-substituted and amide-dodecyl-substituted HATNAs self-assembled into nanowires and formed organogels. These nanowires could be easily transferred onto solid supports through spin casting for morphological study. In addition to the solution-based self-assembly method, solvent-vapor annealing (SVA) was explored as an alternative way to control the organization of supramolecular nanowires on surfaces. It was found that amorphous thin film of HATNA molecules transformed gradually into nanowire structures through a nucleation and growth mechanism during the SVA process. Several parameters including the preordering of molecules in the original thin film, choice of solvent vapors, annealing times, and surface properties were tuned to create different supramolecular organizations. Under particular conditions, aligned nanowires with preferential direction can be achieved.

In the literature, a few biological cells have been used as templates to form microcapsules of a variety of shapes and sizes. In this study, we proved the concept that living cells like platelets can be encapsulated with polyelectrolytes using electrostatic layer-by-layer self-assembly (LBL), and, most importantly, the encapsulation process did not induce activation of the platelets. Glycol-chitosan and poly-L-glutamic acid were electrostatically deposited onto platelets, and the encapsulation was confirmed using confocal laser scanning microscopy and scanning electron microscopy. Transmission electron microscopy observation further confirmed that the encapsulation process was mild and the activation of platelets was negligible. The encapsulation of living biological cells like platelets can serve as a model system in a wide range of biomedical applications including local and sustained drug delivery, immune protection of artificial tissues, and versatile artificial blood.

Self-assembled monolayers (SAMs) were formed on gold at anodic potentials from solutions containing two different alkyl thiosulfates, CH3(CH2)10S2O3Na and HO2C(CH2)10S2O3Na. The resulting two-component SAMs were analyzed using x-ray photoelectron spectroscopy to relate their compositions to those of the solutions from which they were adsorbed. This relationship was more linear than reported for analogous SAMs adsorbed from mixed solutions of alkanethiols. The wettability of these surfaces by water and by hexadecane was also measured and compared to analogous SAMs prepared by chemisorption of thiols from solution.

Molecular films have been extensively used for crystal growth. The Langmuir–Blodgett (LB) technique allows the oriented molecules film to be produced in a controllable manner. By controlling the LB film surface pressure and tuning quenching temperature of the supersaturated solution, single NaCl (100) crystal planes are successfully produced under the surface pressure of 30 mN/m with quenching temperature 5 °C of the NaCl supersaturated solution. The mechanism of single NaCl (100) crystal growth can be further explained based on the best matching between NaCl (100) crystal plane distance and the lattice parameter of LB film among all other crystal planes.

A novel nanoparticle self-assembly process is demonstrated. Nanoparticles were fabricated by a DC magnetron sputtering process. A silicon substrate was initially patterned with arrays of peak and valley photoresist structures using inexpensive patterning techniques. When the nanoparticles were deposited onto the prepatterned substrate, due to surface topography induced local increase in the electric field created by the charges on the nanoparticles, the nanoparticles were self-assembled onto the peaks of the structures and formed long nanowire arrays.

We demonstrate the formation of non-close-packed binary colloidal structures through a novel layer-by-layer directed self-assembly methodology. In this approach we deposit colloidal suspensions of particle concentration and controlled electrostatic potential onto a planar template with a periodic array of features that is able to trap the particles, nucleating ordered domains with a template-defined symmetry and periodicity that permits subsequent, sequential deposition to produce an ordered heterostructure. Specifically, a silicon template with a hole pattern formed by interference lithography that corresponds to [100] symmetry of a cubic system has been used. At low particle concentrations, and using a Debye length that is on the order of the particle diameter, ordered domains in which polystyrene (PS) particles occupy every other site in the template are formed. The remaining sites on the 2D template are then filled by identically sized silica particles using vertical deposition. This process is repeated to produce a second layer of the same structure. Upon removing the PS particles, a two-layer non-close-packed structure that is a half-unit-cell precursor to the diamond cubic structure is obtained. To our knowledge this is the first demonstration of colloidal self-assembly to obtain a non-close-packed multilayer structure. Challenges that remain in applying the approach to create extended three-dimensional structures are discussed.

We show that low-density nanoporous silica monoliths (aerogels), in contrast to the case of full-density silica, exhibit pronounced time-dependent deformation during indentation at room temperature. Logarithmic indentation creep and stress relaxation are revealed, with an exponential dependency of the creep constant on the applied stress. Such time-dependent deformation is attributed to stress corrosion fracture of nanoligaments that have a large surface-to-bulk atomic fraction.