|A10.07 RepAll Omniphobe Oberflächen nach Vorbild der Natur mittels Strukturierung und e-beam unterstütztem Grafting||Dr. Sonja Neuhaus (FHNW Windisch)||Prof. Per Magnus Kristiansen (FHNW Windisch), Dr. Robert Kirchner (PSI), Dr. Celestino Padeste (PSI), Luzia Lötscher (Cellpack AG Packaging, Villmergen), Guillaume Moissonnier (Cellpack AG Packaging, Villmergen)|
|A10.08 Atolys Atomic-Scale Analysis of SiC-Oxide Interface for Improved High-Power MOSFETs||Prof. Stefan Goedecker (Universität Basel)||Prof. Thomas Jung (PSI), Dr. Jörg Lehmann (ABB Switzerland Ltd, Baden-Dättwil), Dr. Holger Bartolf ((ABB Switzerland Ltd, Baden-Dättwil)|
|A10.10 Nano-Cicada-Wing Bactericidal nanostructures mimicking cicada wings for consumer products||Prof. Ernst Meyer (Universität Basel)||Dr. Marcin Kisiel (Universität Basel), Dr. Thilo Glatzel (Universität Basel), Dr. Joachim Köser (FHNW Muttenz), PD Dr. Hubert Hug (DMS Nutritional Products Ltd., Kaiseraugust)|
|A10.13 SurfFlow SurfFlow: A localized surface equilibration process for the generation of optically super-smoothsurfaces for micro-optical lens systems using selective thermal reflow||Dr. Helmut Schift (PSI)||Dr. Sonja Neuhaus (FHNW Windisch), Mirco Altana (Heptagon Advanced Micro Optics, Rüschlikon)|
|A10.14 VERSALITH Versatile Lithography with Multi-Level Phase Masks||Prof. Jens Gobrecht (PSI)||Dr. Vitaliy Guzenko (PSI), Dr. Harun H. Solak (Eulitha AG, Würenlingen), Prof. Per Magnus Kristiansen (FHNW Windisch)|
The research team led by project leader Dr. Sonja Neuhaus from the FHNW in Windisch is also following nature’s example. In the RepAll Argovia project, they are working on the basics for novel surfaces that will repel water and other liquids. To achieve the best result, the research team is examining structured surfaces which are chemically functionalized.
Particular morphology and special coating
As nature has evolved, it has found various ways to prevent surfaces from wetting. The most famous example is the leaf of the lotus flower. Water also rolls off duck feathers and the Salvinia floating fern. The surfaces of lotus flowers, floating ferns, and feathers all demonstrate particular structures. In the case of the lotus flower, particular morphological properties are combined with a water-repellent, wax-like coating that increases the repellent effect even more.
In the RepAll project, Dr. Sonja Neuhaus (FHNW), Dr. Robert Kirchner (PSI) and their industrial partner are investigating various methods of producing surfaces inspired by nature. To do so, they are combining the possibilities of gray-scale electron beam litho-graphy and electron beam-induced grafting. Scalable processes such as roller and hot stamping are used to duplicate the structures.
A10.08 Atolys – From theoretical calculations and experiments to improved high-performance semiconductors
In the Atolys Argovia project, teams of scientists led by Professor Stefan Goedecker from the Department of Physics at the University of Basel are investigating specific components of transistors that are designed for high currents. In the project, researchers from the University of Basel, the Paul Scherrer Institute and ABB in Baden-Dättwil combine theoretical and experimental methods to examine interfaces between silicon carbide and silicon dioxide in semiconductors. The studies, which aim to provide the most precise data about the structure of the semiconductors, will help to further improve devices designed for high currents.
ABB researches high-performance semiconductors
The global trend for increased use of sustainable energies means that innovative and efficient systems must be developed for generating and distributing power. The ABB Corporate Research Center (CRC) in the Canton of Aargau conducts research in this area and develops power electronics that can also intelligently handle large currents at high voltages. A large part of these efforts is devoted to developing and researching materials for high-performance semiconductors. These are used, for example, to convert direct current into alternating current. This is necessary, among other things, to feed power generated through photovoltaics into the grid or to transport power across large distances.
Silicon carbide – the material of the future
The semiconductors of the future may not be made from silicon, but from silicon carbide. Its properties allow smaller devices to be built that are easier to cool and have less resistance. In special semiconductor elements (MOSFETs), the boundary layer between silicon carbide and the insulating material silicon dioxide plays an important role. There is empirical evidence that the number of defects can be reduced with nitrogen and other elements. The microscopic mechanisms that lead to this passivation – the formation of a protective layer – are as yet unknown. To investigate these mechanisms and thus to clarify related questions, the scientific team – including Professor Goedecker, Professor Thomas Jung (PSI), and Dr. Jörg Lehmann and Dr. Holger Bartolf (both ABB) – will combine theoretical simulations with experimental studies and analyze the atomic structure of the boundary layers.
In the Nano Cicada Wing Argovia project, scientists from the Department of Physics at the University of Basel, the School of Life Sciences at the FHNW, and the company DSM in Kaiseraugst are exploring an innovative method of adding bactericidal properties to surfaces without using antimicrobially active substances. In doing so, the researchers are following nature’s example by recreating the structure of cicada wings, which – based on a purely mechanical principle – possess bactericidal properties. They are covered with tiny, nanometer-sized columnar structures that make the wings highly water-repellent. However, bacteria adhere extremely well to the nanocolumns – so well that their cell membranes stretch when the column moves and ultimately break, causing the bacteria to die. The bactericidal effect is based on a purely mechanical principle and not on bactericidal substances or substances with an antibiotic effect. It is hoped that resistance to this mechanical principle will form at a slower pace.
While some Argovia projects aim for rough surfaces to achieve a lotus effect, the SurfFlow project is all about producing microlenses with very smooth surfaces that can be used for optical applications. Dr. Helmut Schift of the Paul Scherrer Institute (PSI) is leading the project team.
New methods are needed
Optical polymer microlenses are used in various devices, including in smartphones. Since they are so small, they have to be processed using novel 3D lithographic methods that build the lenses out of thin layers. However, these often result in roughness, which has adverse effects for optical applications. If a surface has to be subsequently smoothed out, it must be achieved using a method that only modifies the tiny surface and does not change the underlying layers or overall shape. The project team, led by Dr. Helmut Schift (PSI), Dr. Sonja Neuhaus (FHNW) and Mirco Altana (Heptagon Advanced Micro Optics), is studying suitable methods.
Only the surface, not the shape
The researchers are using a method known as TASTE, which was developed at PSI. It involves selectively changing the material properties of the part of the sample that needs modification. For example, an electron beam can selectively reduce the glass transition temperature (the temperature at which the polymers change from a solid state to a viscous melt) in certain areas of the sample. If the sample is then placed in a continuous furnace and allowed to heat up slightly, the treated areas will reach transition temperature and become smooth, while the shape and the lower layers remain virtually unchanged. The scientists hope that this approach will allow them to find ways of making new 3D lithographic methods suitable for use in the production of optical lenses.
Researchers at the Paul Scherrer Institute (PSI), the University of Applied Sciences Northwestern Switzerland (FHNW) and Eulitha AG, a company based in Villingen, launched an Argovia project entitled Versalith at the start of 2015. Under the leadership of Professor Jens Gobrecht (PSI), the researchers are aiming to develop a new method that will advance Displacement Talbot UV lithography to the point where it can transfer patterns at much higher resolution than is currently possible.
Recent years have seen enormous advances in lithographic methods. In particular, researchers involved in the production of semiconductor chips have developed complex processes and tools that make it possible to fit entire circuits into just a few nanometers of space. This has paved the way for producing chips that contain billions of circuits. Other applications, such as LEDs, require lower-cost production methods. However, they must still comply with specific requirements, particularly with regard to resolution.
To produce a semiconductor chip, the entire image of a photomask is scaled down and projected onto a light-sensitive photoresist. The much cheaper Displacement Talbot Lithography (DTL) method, however, uses interference effects to produce a «self-image» of the periodic structure on a photomask, which is then exposed in the photoresist. The image is created via the interference of multiple beams that are diffracted through the periodic pattern of the mask. Even using a relatively simple optical system, this can achieve a structure resolution of less than 200 nm in the photoresist (see www.eulitha.com). So far, this method has only been able to transfer simple, periodic structures. But now the Versalith researchers are investigating the production and use of complex masks that will further increase the resolution and create scope for making other patterns for which the team already have very specific applications in mind. In addition to project leader Professor Jens Gobrecht, Versalith also includes the groups led by Dr. Vitaliy Guzenk (PSI), Professor Per Magnus Kristiansen (FHNW) and Dr. Harun Solak (Eulitha AG).