Erzeugung, Charakterisierung und Strukturierung von Fluorocarbon-Plasmapolymeren für den Einsatz in der Mikrosystemtechnik

New applications for MEMS technologies have been developed by new thin film deposition technologies. Fluorocarbon (FC) plasma polymerisation is of special technical interest due to the excellent and specific properties of the produced polymers appropriate for new applications in the microsystem technology. This work aims to the production of FC-films on and into silicon structures by plasma polymerisation and the characterisation (electrical, chemical, surface, adhesion etc.) of these coatings. Another aim is to develop and investigate new patterning methods which can ensure the use of selective deposited fluorocarbon plasma polymer films in various MEMS applications. In this work, deposition of FC-films was performed in a parallel plate reactor using trifluoromethane (CHF3) as process gas. A careful examination of the dependence of the film properties on the deposition process was carried out by varying the most influencing parameters (gas composition, gas pressure, gas flow rate, coupled plasma power). The produced films have a low surface free energy (contact angle with water more than 104°), a low dielectric constant (approx. 2.09) and a high breakdown voltage (1.35x108 V/m). Further properties of the FC- films such as the chemical stability in various inorganic and organic solutions, the chemical composition and the adhesion to silicon were detailed examined and analysed. The most important part of this work was the examination of various techniques for patterning of the FC-films like the conventional patterning by photoresist masks, the patterning using metal masks and the lift off technology. New technologies for production of selective FC-coatings into deep wet and/or dry etched Si structures were presented. It was possible to produce FC-coatings in the structured areas only, so that the remaining surfaces are not coated (area selective coatings). Due to the experimental results in this study some examples of possible applications of the FC films in the microsystem technology (such as structurable and masking films, hydrophobic coatings and low friction layers, passivation and protective coatings) are proposed in this work.Neue Anwendungsgebiete für die Mikrosystemtechnik werden insbesondere durch neuartige Dünnschichttechnologien erschlossen. Von besonderem technischem Interesse ist die Fluorocarbon-Plasmapolymerisation, da deren Polymere günstige und ganz spezifische Eigenschaften für neue Applikationen in der Mikrosystemtechnik besitzen. Ziel dieser Arbeit ist es, unter Nutzung der Plasmapolymerisation Fluorocarbon-Schichten (FC-Schichten) auf bzw. in Siliziummikrokomponenten zu erzeugen und die Eigenschaften der Beschichtungen (elektrische, chemische, Oberflächen-, Adhäsionseigenschaften etc.) zu untersuchen. Ein weiteres Ziel ist, neue Strukturierungsverfahren zu entwickeln, die den Einsatz selektiv aufgebrachter FC Beschichtungen in verschiedenen mikrotechnischen Anwendungen gewährleisten können. FC-Schichten wurden in einem Parallelplattenreaktor unter Verwendung von CHF3 als Prozessgas hergestellt. Um die Prozesseinflussgrößen auf die Abscheideparameter und auf die Filmeigenschaften zu erfassen, wurde die Plasmaabscheidung in Abhängigkeit von den wesentlichen Prozessparametern (Gaszusammensetzung, -druck, -flussrate, Plasmaleistung) untersucht. Die erzeugten FC-Schichten zeichnen sich durch eine niedrige Oberflächenenergie (Kontaktwinkel mit Wasser über 104°), niedrige Dielektrizitätskonstante (ca. 2,09) und hohe Durchschlagspannung (1,35x108 V/m) aus. Weitere Eigenschaften der FC Schichten wie die chemische Stabilität in verschiedenen Medien, die chemische Zusammensetzung und die Adhäsion zum Si wurden tiefgründig untersucht und analysiert. Der wichtigste Teil der Arbeit bestand in der Untersuchung verschiedenartiger Strukturübertragungsverfahren für die FC-Schichten wie die konventionelle Strukturierung durch Photoresistmasken, die Strukturierung durch Metallmasken und die Lift-off-Technik. Es wurden neue Technologien zur Herstellung selektiver FC Schichten in tiefen nass- bzw. trockengeätzten Si-Strukturen entwickelt. Es war möglich, FC Beschichtungen nur in den strukturierten Bereichen (flächig selektiv) zu erzeugen, wobei die restlichen Flächen unbeschichtet blieben. Aufgrund der gesammelten Erfahrung in dieser Arbeit sind einige Beispiele für mögliche Anwendungen der FC-Schichten in der Mikrosystemtechnik (wie strukturierbare- und Maskierungsschichten, hydrophobe Schichten und Schichten mit niedriger Reibung, Passivierungs- und Schutzschichten) dargestellt

Is there a common therapeutical strategy for bone joints and blood vessels?

Growing evidence demonstrated recently a rationale for the use of orally administered collagen hydrolysate (collagen peptides) in the therapy of patients with osteoarthritis or other arthrodegenerative disorders. At the same time, there is a need for an effective treatment for millions of people in the world with atherosclerosis and its complications mainly due to the rupture of fibrous (collagenous-muscle) cap of the atherosclerotic plaque. Aortic aneurysm dissection in the heritable connective tissue disorders like Marfan, Ehlers-Danlos and Loeys-Dietz syndromes should also be considered herein. This Dance round article argues that the clinical data of collagen hydrolysate and matrix metalloproteinases (e.g., MMP-2, -9) inhibitors might be translated from osteoarthritis to the therapy of atherosclerosis as fibrous plaque stabilizers – this would be a joint of bone joints and blood vessels in action

Current Voltage Characteristics through Grains and Grain Boundaries of High‐k Dielectric Thin Films Measured by Tunneling Atomic Force Microscopy

Leakage current distributions of high‐k dielectric thin films (8 nm HfSixOy and 5 nm ZrO2) were measured by tunneling atomic force microscopy (TUNA). In contrast to the thick HfSixOy film, where grains and grain boundaries can be seen by TUNA topography maps, ZrO2 films show no topography roughness. But large leakage current fluctuations can be seen for both dielectrics by TUNA current images. Higher leakage currents were found to flow through the grain boundaries of both analyzed high‐k dielectric films. Furthermore, local current voltage (I‐V) characteristics could successfully be measured precisely localized at grains and at grain boundaries, respectively, of the ZrO2 film. The obtained local I‐V curves showed significant differences between grains and grain boundaries, respectively. In the case of the ZrO2 film, the leakage current through the grain boundaries was up to 8 times larger than that through the grains at a substrate voltage of −3.5 V

A highly sensitive evaluation method for the determination of different current conduction mechanisms through dielectric layers

Current conduction mechanisms through a metal-oxide semiconductor capacitor with a 9.6 nm thick SiO2 dielectric layer are characterized via Fowler-Nordheim (FN) and Poole-Frenkel (PF) plots, as well as through the analysis of the power exponent parameter α = d(log I)/d(log V). It is shown that the evaluation by means of α is much more sensitive in the accurate identification of different current conduction mechanisms. If FN tunneling and PF conduction occur simultaneously, evaluation using the α-voltage (α-V) plot actually allows one to determine the fraction of each conduction mechanism quantitatively. Even a slight current saturation due to minority carrier depletion, which cannot be detected through the evaluation of the current-voltage characteristics using FN or PF plots, can be detected by the α-V plot