Hexagonally ordered arrays of non‐close‐packed nanoscaled spherical polystyrene (PS) particles are prepared exhibiting precisely controlled diameters and interparticle distances. For this purpose, a newly developed isotropic plasma etching process is applied to extended monolayers of PS colloids (starting diameters <300 nm) deposited onto hydrophilic silicon. Accurate size, shape, and smoothness control of such particles is accomplished by etching at low temperatures (−150 °C) with small rates not usually available in standard reactive ion etching equipment. The applicability of such PS arrays as masks for subsequent pattern transfer is demonstrated by fabricating arrays of cylindrical nanopores into Si.

Among the many phenomena revealed and provided by nanoscience, the functionalization of a surface by nanopatterning certainly holds promise for a large number of attractive applications. A prominent example is the deposition of self-assembled monolayers by microcontact printing in order to control wettability, adhesion, friction, and wear. [1,2] In this context, the well-known lotus effect should be mentioned. This effect is based on a strong reduction of the adhesion of water droplets by nanopatterning a surface with, for example, dense arrays of statistically distributed nanopillars. [3,4] A further application of such nanopillars is their use as effective electron field emitters, as has been demonstrated for Si, [5,6] a material which is also at the focus of the present work, or, more recently, for diamond. [7] Moreover, highly ordered arrays of nanopillars are extremely helpful for the characterization of individual emitters by scanning tunneling microscopy (STM) or scanning tunneling spectroscopy (STS).For an inverted pattern of nanopillars, that is, ordered arrays of cylindrical nanopores with a high aspect ratio, a similar wealth of possible applications can be thought of. For instance, they can serve as contact holes in semiconductors. According to the present semiconductor technology roadmap, they should exhibit diameters well below 80 nm for the "65 nm node generation".[8] Similarly, applications in nanooptics appear attractive; nanopores based on colloidal masks were fabricated into Si with a diameter of 60 nm. [9] Smaller diameters of the order of 30 nm should be obtainable by nanomachining a poly(methyl methacrylate) PMMA resist with an atomic force microscope and subsequent metal-coating and lift-off, thereby accepting the disadvantage of a nonparallel process. [10] Note that the recently developed technique of controlling the diameter of nanopores in ultrathin Si/SiO 2 membranes by the electron beam of a transmission electron microscope is still a nonparallel procedure.[11] Another approach to preparing nanoholes in Si is based on self-organized porous alumina masks in combination with anisotropic Cl 2 reactiveion etching (RIE). [12] In this way, holes with diameters > 13 nm and an aspect ratio of 3 could be obtained. Similar diameters are obtained by a recently reported technique based on the self-organization of inverse spherical micelles formed from diblock copolymers dissolved in an apolar solvent, such as toluene, and selectively loaded in the micellar core with a metal salt, such as HAuCl 4 .[13-16] By dip-coating such solutions onto practically any sufficiently flat substrate, hexagonally ordered arrays of Au nanodots can be prepared by an ashing process.[17] They can be used as nanomasks in a subsequent anisotropic etching step, resulting in corresponding arrays of nanopillars. In this way, hexagonally ordered pillars with a diameter of 14 nm and an aspect ratio of 5 were obtained in Si. This micellar preparation technique offers a number of impressive advantages, such as the control of the...

It is demonstrated that the miniemulsion polymerization technique allows the preparation of highly uniform and practically monodisperse latex particles containing a hydrophobic metal complex like platinum(II)acetylacetonate, indium(III)acetylacetonate, zinc(II)tetramethylheptadionate, zincphthalocyanine, and chromium(III)benzoylacetonate, respectively, with different loading capacities. For some platinum and iron complexes, the homogeneity of the latexes can be improved even further by adapted emulsion techniques. By choosing different amounts of surfactant, we can adjust the particle size between 100 and 260 nm. To obtain larger particles up to 370 nm for a given metal complex, we performed an additional feeding of monomer. In this way, the particles can be easily modified by changing the polymer or the copolymer composition. Using a pure polymer core and semicontinuously adding a complex/monomer mixture leads to an increased size of the particles, which can contain additional metal complexes. The methodology was also applied for the preparation of alloyed Fe/Pt particles. The concentration relations were analyzed by inductively coupled plasma spectroscopy (ICP) and, mostly, energy-dispersive X-ray spectroscopy (EDX). When particles are deposited onto a substrate, the high homogeneity of the particle size results in hexagonally well-ordered monolayers of the metal-containing polymer particles. Such an encapsulation of metal complexes into particles of defined size makes them suitable for a wide variety of applications, especially in the context of nanolithography.

Based on emulsion polymerization in the presence of a Pt complex, polystyrene (PS) particles were prepared exhibiting a well defined average diameter with narrow size-distribution. Furthermore, the colloids contain a controlled concentration of the Pt precursor complex. Optimized coating of Si substrates with such colloids leads to extended areas of hexagonally ordered close-packed PS particles. Subsequent application of plasma etching and annealing steps allows complete removal of the PS carriers and in parallel nucleation and growth of Pt nanoparticles (NPs) which are located at the original center of the PS colloids. In this way, hexagonally arranged spherical Pt NPs are obtained with controlled size and interparticle distances demonstrating variability and precision with so far unknown parameter scalability. This control is demonstrated by the fabrication of Pt NP arrays at a fixed particle distance of 185 nm while systematically varying the diameters between 8 and 15 nm. Further progress could be achieved by seeded emulsion polymerization. Here, Pt loaded PS colloids of 130 nm were used as seeds for a subsequent additional emulsion polymerization, systematically enlarging the diameter of the PS particles. Applying the plasma and annealing steps as above, in this way hexagonally ordered arrays of 9 nm Pt NPs could be obtained at distances up to 260 nm. To demonstrate their stability, such Pt particles were used as etching masks during reactive ion etching thereby transferring their hexagonal pattern into the Si substrate resulting in corresponding arrays of nanopillars.