Narrow Results

Interferometric lithography offers a facile, inexpensive, large-area fabrication capability for the formation of large areas of nanoscale periodic features. A self-aligned frequency doubling process to a 22-nm half-pitch is demonstrated. Many investigations of nanoscale phenomena require large-area samples, both for scientific investigations and certainly for ultimate large-scale applications. The utility of interferometric lithography is demonstrated to applications in nanophotonics and nanofluidics. For nanophotonics, metamaterial fabrication, negative index metamaterials and plasmonic applications are discussed. Two approaches to the fabrication of nanofluidic structures: etching and oxidation of silicon substrates, and colloidal deposition of silica nanoparticles to form porous walls and roofs followed by calcination to remove the photoresist and sinter the particles. These later structures have evident biomimetic functionality.

In the past decade, the development of nanoelectronics and nano-optics has attracted much interest in surface nanostructuring of semiconductor materials. The irradiation of a microlens array by a laser beam generates many focused light spots, which can act as a direct writing tool on photo-polymer materials. This maskless surface nanostructuring technique enables thousands to millions of identical nano-features to be patterned in a couple of laser pulses. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images show that nano-features were patterned uniformly on the substrate surface, which suggests a versatile way of parallel surface nanostructuring over a large area. The simulation results of the energy flux distribution at the focal plane of the microlens arrays will also be discussed.

This paper reports an investigation into electrospraying a nanosuspension containing nanoparticles sized at 5 nm and suspended in a polymer grade ethylene glycol. Hence, the processing of this nanosuspension in the stable cone-jet mode having an amorphous silica powder loading of 30 wt.% is elucidated. A comparison is made with established literature on jet break-up to identify the break-up mechanism in this investigation. The ensuing electrospray characteristics for both the polymer grade ethylene glycol and the nanosuspension are also presented. Using the data of collected droplet relics together with a volume equivalence method, the generated droplet sizes are estimated for both media and are compared with the well-known theoretical expression for calculating the droplet sizes generated for that respective jet break-up regime and medium. Finally, transmission electron microscopy of the collected deposits concludes the discussion presented in this investigation.

This study briefly reports a newly developed nanopatterning technology utilizing a so-called micro droplet jetting system, which can be used in various applications such as nanofabrication. Compared with the conventional methods, this technology has the advantages as follows: it can be manipulated easily and patterned freely as the user requires; furthermore, it shows high-reliability and high-stability with very low cost. The typical specs of the micro droplet jetting system for fabricating nanodevice show as follows: (1) nanoparticle size: 50–60 nm; (2) characteristic wavelength: 400–450 nm; (3) volume of droplet: 6 ppl; (4) size of pixel: 70 μm. In this article, the nanopatterning technology adopting the micro droplet jetting system has been demonstrated to be useful for nanopatterning the pixels which consist of nanoparticles, organic luminescent materials. In addition, the micro topography and the luminescent property of the patterned surface have been characterized by using Scanning Electron Microscope (SEM) and fluorescence microscope, respectively. Finally, the fluorescence of the patterned nanoparticles was observed.

In the race to downsize the features of components in integrated electronics, nanostructure fabrication is a primary challenge. Semiconductor technology has always relied on the top-down approach such as conventional CMOS technology for surface structuring and patterning. The most remarkable example is the amazing miniaturization of transistors and data storage components by ever more sophisticated lithographic techniques. Nevertheless, the so far unbeaten nanofabrication techniques such as deep-UV (DUV), extreme-UV (EUV) or electron-beam lithography (EBL) are particularly dedicated for patterning motifs in photo or electron-beam resists, spin-coated on planar, ultra-flat semiconductor surfaces. Alternative fabrication processes for growth of integrated novel nanostructured functional materials are already foreseen in related areas such as micro/nano-electro mechanical systems (MEMS/NEMS), sensors and actuators, optoelectronics, bio-chips, plastic or molecular electronics, etc. In other words, appropriate patterning methods are explored for creating and positioning structures with nanometer dimensions (<100 nm) on non-planar (e.g. curved or rough) surfaces or other functionalized and often fragile surfaces (membranes, cantilevers, organic layers). In this context, a variety of other forms of parallel lithography such as molding, stamping, imprinting or stenciling are revisited for their potential as nanofabrication alternatives that alleviate conventional lithography limitations. Thus, fabrication of functional structures with controlled size and shape, precisely positioned on a substrate of choice, using a minimal number of processing steps, becomes a central issue in nanotechnology. Furthermore, growth of novel nanostructured complex materials with functionality represents a big challenge for materials development. Probing new routes to prepare these materials and understand the relationship between their size/structure and their properties is also essential to the development of related technologies.

Significant advances in defining nano-patterns have been made by nanoimprint lithography (NIL). NIL is able to deliver features well below 100 nm, rapidly and with high accuracy, at least compared to advanced optical lithography methods. Either by hot embossing technique (HET) or its related variant, step and flash imprint lithography (S-FIL) nanoimprint shows great potential for the semiconductor industry and has been already placed on the International Technology Roadmap for Semiconductors (ITRS) for the next years. Another promising approach, although less investigated to date, is nanostenciling, known also as controlled growth of nanostructures through a shadow-mask. This process has been proposed both in static or dynamic mode and projected as a suitable method to locally grow patterned nanoscale structures, in a single, resist-less, deposition step. While offering a high degree of freedom in choosing the physical vapor deposition method, nanostenciling is in principle applicable to the deposition of arbitrary materials on almost any substrate. It drastically reduces the number of processing operations with respect to resist–based lithography and therefore represents a promising "universal tool" for local deposition of high-resolution and high-purity 3D nanostructures under high or ultra high vacuum (UHV) conditions.

We provide fundamental and extensive descriptions of stenciling and imprint processes and outline the main concepts used for the fabrication of both stencilmasks and molds. Then, through a couple of detailed examples we will emphasize the importance of several particular parameters involved in these processes (e.g. geometry and methods of deposition for stenciling, molds, resists, tools in the case of imprinting). Finally we will present a couple of examples where either nanostenciling or nanoimprint have been successfully used for device applications and in conclusion offer our perspective on future potential applications (prototyping) in areas where other forms of lithography are much less suitable.

Interferometric lithography offers a facile, inexpensive, large-area fabrication capability for the formation of large areas of nanoscale periodic features. A self-aligned frequency doubling process to a 22-nm half-pitch is demonstrated. Many investigations of nanoscale phenomena require large-area samples, both for scientific investigations and certainly for ultimate large-scale applications. The utility of interferometric lithography is demonstrated to applications in nanophotonics and nanofluidics. For nanophotonics, metamaterial fabrication, negative index metamaterials and plasmonic applications are discussed. Two approaches to the fabrication of nanofluidic structures: etching and oxidation of silicon substrates, and colloidal deposition of silica nanoparticles to form porous walls and roofs followed by calcination to remove the photoresist and sinter the particles. These later structures have evident biomimetic functionality.