Despite a large and growing volume of papers on nanotechnology, commercialization of these technologies has been restricted by the lack of driving applications, and the ability to produce nanotechnologies at scale. This Special Topic addresses the second of these challenges, by examining the state of “nanomanufacturing”, reviewing a commercial success in the field, and introducing processes that have promise for mass production. The topic is being introduced with seven invited papers, with more anticipated in coming months. We hope it will inspire more work on nanomanufacturing, encourage discussion of manufacturability, and illuminate a roadmap for researchers addressing challenges in nanomanufacturing.
A two-phase barium titanate/cobalt ferrite nanowire-based magnetic sensor offers enhanced performance as compared to thin films. Magnetoelectric devices are attractive for magnetic field sensing, and have so far been mostly based on composite thin films of magnetostrictive and piezoelectric phases. However, the film substrate typically limits the size of the magnetoelectric effect, reducing their sensing performance. Now, a team from University of Florida led by Jennifer S. Andrew fabricated composite barium titanate/cobalt ferrite nanowires by electrospinning and suspended them over electrodes, removing the substrate constraints experienced by thin films. Resultantly, their device displays a high magnetoelectric coefficient of 514 ± 27 mV cm−1 Oe−1. This work demonstrates the potential that one-dimensional materials offer for magnetoelectric based devices including magnetic field sensors.
Nanoimprint lithography steppers for volume fabrication of leading-edge semiconductor integrated circuits
An appraisal of sub-40nm half-pitch lithography technologies for high-volume manufacture of semiconductor integrated circuits is provided. Although cutting-edge semiconductor lithography has been an important driver for the electronics industry, only a small subset of researched nanolithography techniques have been explored for mass production in semiconductor integrated circuits fabrication facilities. By assessing the evolution of a nanoimprint technique known as jet and flash imprint lithography (J-FIL) stepper technology, S. V. Sreenivasan at the University of Texas at Austin, United States, has identified the main characteristics for insertion of J-FIL for fabrication of semiconductor memory with sub-20nm half-pitch structures. The demonstrated ability of nanoimprint to pattern resist structures of less than 5 nanometers makes it an attractive choice for potentially extending the scaling roadmap for high volume semiconductor manufacturing.
Computer-aided design could aid the mass production of micro- and nanodevices, according to a review of manufacturing techniques. Despite advances in manufacturing technologies, developing scalable and flexible, high-yield manufacturing processes on the nanoscale is still a considerable challenge. To help overcome this, Sung-Hoon Ahn and colleagues from Seoul National University in South Korea and the University of Wisconsin–Madison in the United States surveyed current fabrication technologies to identify the features of computer-aided design and manufacturing (CAD/CAM) systems that are necessary for the development of high-volume nanomanufacturing processes. The researchers demonstrated a CAD/CAM hybrid process based on a network that promotes communication between users and operators, and is capable of printing a 3D structure on the nanoscale using inorganic materials.
Scaling behavior of nanoimprint and nanoprinting lithography for producing nanostructures of molybdenum disulfide
A simple stamping method could create electronic devices from 2D materials, researchers in the United States show. Techniques used in mass manufacture of electronic devices can process silicon into structures of less than a micrometer in size. But if other types of electronic material are to become as influential as silicon, similar methods will be needed to reproducibly fabricate their tiny devices. Xiaogan Liang and co-workers at the University of Michigan investigated the size limit of structures comprising 2D materials. The researchers used nanoimprint-assisted shear exfoliation to produce atomic monolayers and multilayers of the 2D semiconducting molybdenum disulfide. The technique involves stamping the material with a desired pattern and then pulling off a thin layer. They showed that the lateral size of the stamp sets a minimum layer thickness below which the material becomes damaged.
Printing with a special ‘E-jet ’ printer allows nanoparticles to be assembled on surfaces with high precision. Electrohydrodynamic-jet ( E-jet ) printing uses electric fields to pull tiny conical droplets from an inkjet nozzle, enabling the construction of 3D devices with a resolution below 50 nanometers. Harish Bhaskaran and colleagues from the University of Oxford, United Kingdom, now demonstrate that combining E-jet-printed monolayers of aminosilane with electrostatic self-assembly may bring gold nanoparticles — valued for their biosensing capabilities — into the integrated workflows of nanomanufacturing. The team selectively printed both planar and recessed monolayer nanotemplates onto a silica substrate, then added a liquid solution of gold colloids. The gold spheres formed linear patterns exclusively in the template regions, as confirmed through an innovative in situ Kelvin probe microscopy technique that works in disruptive environments such as polar solvents.
New methods pave the way for the high-volume manufacture of complex micro- and nanostructures with a high aspect ratio (HAR). HAR microstructures have uses in a variety of applications, including gas chromatography and X-ray optics, but making such structures with height-to-width ratios of 10 or more is particularly challenging. To address this, Helmut Schift and his colleagues from the Paul Scherrer Institute, Switzerland, in partnership with German company micro resist technology, used two emerging technologies for manufacturing HAR microstructures to help fabricate nanoridge structures with aspect ratios of up to 28. The team’s work provides molding tools for fabricating HAR microstructures that combine hard and soft materials, and confirms that the emerging technologies are compatible with the replication of complex micro- and nanostructures, holding promise for the development of innovative nanophotonics applications.
Rapid synthesis of transition metal dichalcogenide–carbon aerogel composites for supercapacitor electrodes
A fast and scalable technique for manufacturing nanoscale supercapacitors could lead to better performing energy-storage technologies. Supercapacitors made from transition metal dichalcogenides (TMDs) have the potential to replace lithium batteries as an energy-storage technology. However, they are prone to mechanical failure and their production often requires unstable, dangerous chemicals, which restricts their application. To address these limitations, Peter Pauzauskie and colleagues from the University of Washington in Seattle, United States, have developed a method for fabricating operationally stable nanocomposite supercapacitors that combines the high-capacitive properties of TMDs with the the electrically conductive, porous characteristics of pyrolyzed carbon aerogels. By encapsulating sheets of TMDs in a resorcinol-formaldehyde resin, the researchers demonstrate a safe, ultrafast, and inexpensive process that could lead to new devices for photovoltaic and catalytic applications.
A controlled fracturing process developed by Swedish researchers makes it easier to produce electrodes separated by just a few nanometers. DNA sequencers and quantum computers stand to benefit from nanoscale-gap (nanogap) devices that use tunneling currents to probe molecules and light–matter interactions. Instead of conventional fabrication based on chemical etching, Valentin Dubois and colleagues at the KTH Royal Institute of Technology report that nanogaps can be reliably formed by stretching conductive bridge structures until they crack. The team modeled and microfabricated a variety of bridges with different lengths, anchor points and stress-focusing points to uncover design parameters needed to produce self-generated, atomic-scale junctions. They found that with tiny-notched cross sections and cooling-initiated crack formation, the yields of nanogaps with pristine electrode surfaces could be high enough for wafer-scale manufacturing.