polar liquid layer on the substrate which serves as a transfer mechanism; therefore they are still costly for high volume manufacturing of transparent electrodes in lowcost applications. Other options, such as randomly distributed metal nanofibers [7] or nanowire networks [8,9] allow no control of the location and pattern of the wires as they are always randomly distributed on the substrate. On a micrometer scale of creating silver wires, inkjet [10] and gravure printing [11,12] are low-cost additive methods used for printed electronics, yet with resolutions often in the range much larger than 10 µm. [13] They are not suitable for applications where sub-micrometer or even sub-100 nm resolutions (e.g., for subwavelength optics) are needed. In order to shrink dimensions without using traditional lithography, the patterning of nanoparticles by self-assembly on pre-patterned substrates is a solution. It has been tested for the generation of dense arrays of 50-80 nm silica particles in V-grooves. [14] Capillary assisted particle assembly (CAPA) is used for the parallel assembly of sub-micrometer particles into hexagonal arrangements by convective or capillary effects. [15,16] However, nanoparticle inks have polydisperse distribution of particle sizes (here between 20 and 80 nm) and therefore typically do not self-assemble but rather form a loose agglomeration, which is merged into a 3D cluster by post-processing (e.g., sintering).The objective of the present paper is to provide a novel method for reducing the width of structures generated by ink deposition on pre-patterned substrates. We aim to achieve resolutions which are not only much smaller than the resolution of the applied additive process, but also smaller than the width of the pre-patterned structures. Pre-patterning the substrates with specific sub-micrometer topography can be done by straightforward replication techniques such as thermal or UV-assisted NIL which can then be covered either locally (e.g., by inkjet printing) or on an entire substrate (by spincoating). This enables the generation of fine structures in the micrometer range down to subwavelength range at low cost and high throughput, and thus satisfies the demand for a technology being less expensive than currently known lithographic processes. In the process proposed here, we use this approach to fill V-groove shaped substrates with silver nanoparticle-based inks, typically with average 50 nm particles dispersed in a suitable solvent. [17] The nature of the V-groove substrates with inclined sidewalls and Λ-ridges between adjacent grooves separates individual lines Here, the fabrication of sub-200 nm metal wires from commercial silver inks with 50 nm particle size, 100 times narrower than with typical low-resolution ink-jet and screen printing in flexible electronics, is demonstrated. Using a combination of spincoating on prepatterned polymer substrates and flash lamp annealing, nanoparticles merge to wires featuring good electrical conductivity. With this method less than 150 nm thin wires can ...
The novel use of metal/polymer composite can be a new candidate for filling through silicon vias (TSV) for three-dimensional (3D) LSI, as it provides a much faster and inexpensive fabrication process compared to copper electroplating. In this study, different process methods have been tested in order to optimize TSV filling with Ag/polypyrrole composite. All together nine method set-ups have been examined to analyse their average filling ratios. The statistical analysis of the techniques showed that the masking and scratching in vacuum environment proved to be the most effective, in average up to 98% filling ratio could be reached within 5 min. The technological differences of the two techniques to remove the additional deposited composite material on the surface caused by the wet dipping in aspect of the resulting via fillings are also detailed in this paper. The use of these techniques can contribute to improve through-put for production of 3D-LSI with metal/polymer composites.
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