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Fast heavy ion beam-based lithography using masks of self-assembled materials has been applied for transferring well-ordered nano- and micropatterns to rutile TiO2 single crystals. As the induced damage has a high etching selectivity the patterns can be developed in hydrofluoric acid with very high-contrast. Here we present resulting patterns when using a mask of self-ordered silica spheres. The obtained pattern are replicas of the mass distribution of the mask. In addition the shape and size of the regular structures depend on the applied ion energy and fluence. Direct modifications of the optical properties of TiO2 in a well-defined pattern are also presented.

Swift heavy ion beam-based lithography using masks of self-assembled materials has been applied for transferring well-ordered micro- and nanopatterns to rutile TiO2 single crystals. As the induced damage has a high etching selectivity the patterns can be developed in HF with very high contrast. Here we present resulting patterns when using a mask of self-ordered silica spheres. Since the obtained structures are replicas of the mass distribution of the applied mask, the shape and size of resulting structures depend on the geometric configuration of the silica sphere layers. In addition, the resulting pattern can be tuned by varying the applied ion energy and fluence. Direct modifications of the optical properties of TiO2 in a well-defined pattern are also presented.

This broschure was produced for the inauguration of WISENET December 7, 2007. It decribes the future impact of WISENET, application areas and the 10 partners. The three research areas "Node Integration & Energy", "Networkning & Security" and "Wireless Communication" is briefly described as well as the application projects in "Water Sensing" and "Transport"., wisenet

A fabrication process for small through-hole vias consisting of multiple sub-micron electrodeposited wires has been developed for flexible printed circuit boards (PCB). The resistance of the vias is controlled by adjusting the number of wires per via, as well as the dimensions of the wires. The process steps include modification of the foils by irradiation with energetic ions, wet etching and metallization of the through-hole vias, double-sided surface metallization of the dielectric layer and interconnection lithography. Series of up to 360 interconnected vias of electrodeposited nickel are demonstrated in a flexible PCB foil (75 µm Kapton HN polyimide). The vias have a lateral size of 26 µm. The metal content of the demonstrated vias is 0.12% and 10% of their total volume, corresponding to a metal cross-section of 3.2 µm2 and 270 µm2, respectively. The electrical resistance per interconnected via is 2.6 Ω and 0.07 Ω, respectively. The vias can carry a current density of at least 4 × 106 A cm−2.

A fabrication process for vertical thermopiles embedded in a 75-mu m-thick polyimide foil has been developed for flexible printed circuit boards (flex PCBs). The vertical connections consist of electrodeposited antimony- and nickel-plated through-hole vias. The plated through-hole vias consist of multiple wires, with a total metal content that is 1% of the total via volume. The via fabrication technique is similar to standard flex PCB wet etch and metallization processes. The main difference is that the foils are pretreated with ion irradiation to induce highly selective vertical etch rates. The thermopiles were characterized by measuring their voltage response to an applied temperature difference across the foil thickness., wisenet

The authors present a method for high aspect ratio nanopatterning of high density (1010 pores/cm2) self-assembled porous alumina membrane pattern into thermally grown SiO2 on silicon. The pattern transfer is accomplished by irradiating through 2 µm thick porous alumina membrane with swift heavy ions (4 MeV Cl2+). Ions passing through the nanopores in the mask at a fairly high fluence (typically 1014 ions/cm2) are impinging on the substrate and creating a continuous volume of overlapping ion tracks of damage. The damage is sufficient to be selectively etched by HF vapor from an aqueous HF solution. From an alumina mask with pores of 70 nm diameter, a pattern of pores of 77 nm in diameter and the same distance of 100 nm between the centers of the pores was transferred. The deepest observed etched pores were 355 nm, giving an aspect ratio of 5, which is up to 40 times larger compare to earlier work where HF wet etching was used. This ion track lithography technique shows a potential to produce nanostructures with even higher aspect ratios.

The changes in structural and magnetic properties of FePt thin films due to the irradiation with high energy ions (Br7+ and Cl2+) were studied. From the hysteresis loops dominating in-plane anisotropy is derived, however, the samples present a minor out-of-plane component. The structure and the magnetic properties of the films can be tuned by selecting the appropriate irradiation parameters (different ions, energies and fluencies). For the irradiation parameters used in this study an in-plane anisotropy is favoured. Irradiation with Br7+ seems to induce minor changes in the structural ordering of the thin films, whereas the Cl2+ ions promote the amorphization of the surface of the films. In addition, a magnetic thin film pattemed at the micrometer scale was obtained after irradiation through a micrometric mask.

A method for producing ordered carbon nanopillar arrays is presented. The method is based on ion irradiation through a small anodic porous alumina membrane, resulting in carbon deposition within the centers of the pores on a gold covered SiO2/Si substrate. Samples were irradiated by 4 MeV Cl2+ ions with fluences of . The combined use of pick’n place positioning of the small porous alumina templates and ion beam irradiation is well suited for post-processing on silicon based integrated circuits. It provides fast local deposition at low temperature of high-density ordered carbon nanopillar arrays in larger silicon based systems, e.g., for field emitting or biosensors applications.

Ion track lithography has been applied for transferring the self-ordered nanopattern of porous anodic alumina to single-crystalline rutile TiO2 substrates. As a result, nanometre resolved arrays have been fabricated with an aspect ratio ranging from 5 to 16, over areas of several square millimetres. Differences in the expected aspect ratio of the resulting nanopores in rutile TiO2 single crystals are analysed and discussed. Some of these differences may be ascribed to varying densities of the mask material.

Among the microfluidic separation methods, hydrodynamic spreading is a simple and high-throughput continuous separation technique based on the difference in size. However, it is difficult to adjust tiny pressure differences accurately in microfluidic devices. In this study, a combination of electroosmotic flow (EOF) and hydrodynamic flow spreading was employed to tune the size separation of particles. A stream with different kinds of particle suspensions was driven co-fluently with a particle-free carrier stream under both mechanical external and electroosmotic pressure in a microchannel. The EOF-tuned hydrodynamic spreading behaviour was investigated experimentally and modelled through an electric equivalent model and numerical simulation. When the magnitudes of the mechanically and electroosmotically induced pressures were similar, the EOF tuning on the pressure-driven flow became significant. Hence, the hydrodynamic spreading could be easily adjusted by a tuned power supply. The separation was studied in more detail with 1.9 and 9.9 µm fluorescent polystyrene particles. Moreover, separation of E. coli and yeast cells was accomplished. In conclusion, this technique has the advantages of good stability of mechanical-pressure-driven flow and precise tuning of the EOF, and provides a robust method for size-based separation of particles and cells.

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Polycarbonate templates of ( 30 +/- 1) mu m thickness containing cylindrical etched-track nanochannels of ( 500 +/- 50) nm diameter were used for electrodeposition of Ni nanowires. Using 10(4) channels per cm(2), the most favourable deposition potential of -1.0 V was determined in a potentiostatic mode by varying the deposition potential with respect to an Ag/AgCl reference electrode over a range between -0.1 V and -1.5 V. The deposition efficiency at -1.0 V was estimated around 10%. The resulting single wires had a resistance around 200 W and showed an anisotropic magnetoresistance (AMR) effect of 1%, applicable to directionally sensitive magnetic field sensors.

In this work a successful method for producing high-aspect-ratio nanopatterned single-crystal TiO2 is presented. The method used is based on nanolithography involving swift heavy ion bombardment through a porous anodic alumina mask. Nanopatterning of large areas allows for fabrication of new devices, for example, photonic crystals and electrodes for energy storage and conversion. Crystalline TiO2 also presents optimal characteristics for optical and catalysis applications. Samples were irradiated by MeV Br7+ ions with fluencies ranging from 7.9 × 1013 to 1.2 × 1015 cm-2. The high-energy Br7+ ions induce latent tracks of amorphous material into the TiO2 crystal suitable for selective etching by hydrofluoric acid. High-aspect-ratio (16) nanopatterned areas, up to 4 mm2, were obtained in a single radiation spot onto single-crystalline TiO2.

Self-assembled nanoporous alumina films were employed as masks for MeV ion track lithography. Films with thickness of 2 µm and pore diameters of 30 and 70 nm were attached to thermally grown SiO2 covered with a thin gold layer. The samples were aligned with respect to the beam by detecting backscattered He+ ions with the initial energy of 2 MeV. The ordered pattern of the porous alumina films was successfully transferred into SiO2 after irradiation with a 4 MeV Cl2+ beam at fluence of 1014 ions/cm2, followed by chemical etching in a 5% HF solution.