Erlangen, Nürnberg, University, Diss., 2002.

Three types of major process-induced damage which hampers the realization of FRAM (ferroelectric random access memory) device are investigated; dry etching induced damage, hydrogen-induced degradation, and stress effect. Since ferroelectric capacitors utilize the movement of body-centered atoms in perovskite structure, Ti or Zr in the case of Pb(Zr/x Ti/1-x)O³ (PZT), the movement can be suppressed or inhibited by many factors such as space charges, defects, chemical reactions, and stress of stacked layers. Unlike conventional silicon processes, the integration of ferroelectric capacitor module requires high density plasma to pattern their shapes because of a low volatility of etched byproducts, therefore the degradation of ferroelectric capacitor performance could occur by the collision of high energetic particles. The damage of PZT thin film due to dry etching process was characterized in terms of the microstructure and electrical properties. The damaged layer seems to be amorphous and the thickness is about 10 nm. The existence of such a layer in Pt/ PZT/Pt ferroelectric capacitor tends to increase the coercive voltage and the leakage current. The damaged layer was not fully reverted to perovskite phase by the thermal annealing, even at PZT formation temperature. For the elimination of this damaged layer, a novel wet cleaning solution was designed. Scanning electron microscopy (SEM) pictures clearly show that treatment with the cleaning solution completely removed the etching damaged layer. With the cleaning solution, a sidewall cleaning process and a surface cleaning process were proposed to eliminate non-ferroelectric phases such as pyrochlore, PbO, and etching damaged layer. After removing the non-ferroelectric phases, ferroelectric properties such as remnant polarization, coercive voltage, and leakage current were remarkably improved. In addition, the wet cleaned ferroelectric capacitors yielded superior endurance against hydrogen-induced damage compared to those of the non-cleaned capacitors. Several parameters such as Zr/Ti compositional ratios, excess amounts of Pb, the domain poling state, and electrode structures (Pt/PZT/Pt and Ir/IrO₂/PZT/Pt/IrO₂) were investigated in terms of hydrogen-induce degradation. It was found that the hydrogen-induce degradation is enhanced when PZT films have high compositions of Ti and Pb, and can be suppressed by domain poling prior to the hydrogen anneal. From the SIMS analysis and hysteresis loop shifts, it can be concluded that the hydrogen damage occurs mainly at the PZT/electrode interface and results in the development of negative charge buildup. To reduce the hydrogen-induced damage, an electron cyclotron resonance (ECR) oxygen plasma treatment of the Pt/PZT/Pt capacitor was attempted. It was found that oxygen plasma treatment modifies the surface of Pt electrodes. Surface modification alleviates catalytic activity of Pt electrodes, thereby significantly improving ferroelectric properties such as remnant polarization and leakage current. It seems that highly reactive oxygen radicals in ECR plasma play an important role in suppressing the catalytic activity of Pt electrodes. The cause of the blister formation on the PECVD (plasma enhanced chemical vapor deposition) SiO2/Pt/PZT/Pt capacitor was studied by means of annealing in various ambient. The blisters were observed at a temperature of 325°C in an O₂ atmosphere, while in a N2 and an Ar atmosphere blisters were not produced even at 500°C. Hydrogen evolution analysis from PECVD SiO2 layer showed a sharp peak near 320°C. The results indicate that the accumulation of water vapor pressure, developed via a chemical reaction between oxygen and hydrogen could be the dominant factor for blister formation in PECVD SiO₂/Pt/PZT/Pt capacitors. The effect of stress was investigated with two different interlayer dielectric (ILD) materials, ECR CVD Oxide and PECVD TEOS Oxide (PE-TEOS). Since the stress of PZT capacitor strongly depends on the ILD deposition temperature, the PZT capacitor with PE-TEOS showed more compressive stress than that with ECR oxide, which results in severe remnant polarization (Pr) degradation of PZT capacitor with PE-TEOS. This large stress effect of PE-TEOS was confirmed by measuring d-spacing values of (111) PZT films with XRD technique. These results suggest that the low ILD deposition temperature is a key parameter for achieving an ILD integration with a minimal Pr degradation. / Ph. D.

Techn. Hochsch., Diss., 2002--Aachen.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Comparison of short-range telemetry and radio frequency identification (RFID) systems reveals that they are based on very similar operating principles. Combining the identification and measurement functions into one transponder sensor offers added value for both RFID and telemetry systems. The presence of a memory (e.g. FRAM) in the transponder, required for ID information, can also be utilized for storing measurement results. For passive transponders low power consumption is one of the main objectives. Wireless power transfer for passive transponder sensors together with above aspects concerning a combined telemetry and identification system are discussed.

<p>Command and Control (C2) refers to the process or function of commanding and controlling military or civilian units. For most military context C2 is exercised in an adversarial environment where two or more forces are fighting against each other. In these situations it is desirable to constrain the adversarial forces in order to prevent them from achieving their objectives. By maintaining an accurate view of the possible dependencies and couplings within the own forces and between the own and adversarial forces, constraints can be managed and coordinated.</p><p>The purpose of this thesis is to develop a model that is capable of capturing these dependencies and couplings. This model is developed using the Functional Resonance Analysis Method (FRAM; Hollnagel, 2004). FRAM builds on the assumption that all parts of the system can be described as functional units. These functional units can then be linked together to form large systems. The links themselves are defined by how a function may affect other functions or in turn be affected by them. This enables the model to incorporate complex interactions within the system as well as between two adversarial systems.</p><p>The microworld “Dynamiskt Krigsspel för Experiment” (DKE) was used to develop the model. A scenario with two teams battling in this adversarial microworld setting was analyzed in detail for this purpose. The developed model uses three different layers, or resolutions, of functions to capture all potential couplings between functions. The lowest level of functions, called the tactical level, is the physical actions of the units in the microworld. The next level, the operational level, concerns the more overarching goals for which the tactical functions are used. Last, the strategic level consists of the C2 functions, such as data collection, sensemaking and planning.</p><p>The developed model is then applied to the scenario in DKE and shown to be able to describe and explain all actions by the two adversary systems as well as the couplings and dependencies between them.</p>

<p>The Functional Resonance Accident Model is a method developed to analyze complex systems for the purpose of accident prevention. In FRAM-analysis a visualization of the complex system is created as an aid for identifying points of interaction in the system where the risk of accidents is high, and to determine where preventive measures are to be placed. FRAM Visualizer is a computer program developed as a tool for creating such visualizations.</p><p>Many usability problems have been identified in FRAM visualizations created both manually according to established method and by using the FRAM Visualizer software. The purpose of this paper is to give a basis for how FRAM visualizations can be improved in accordance with usability criteria for use in future qualitative studies.</p><p>The author suggests alterations to the FRAM visualization to resolve usability issues identified in previous articles and to achieve usability goals derived from visual communication theory. The design process is guided by established design principles. The author outlines a proposal for usability testing of the redesigned FRAM visualization to verify that it achieves the usability goals.</p><p>The author concludes that though the redesign offers solutions for the most important problems (providing the user with detailed information as a basis for analysis and enabling the layout of clearer and more easily overviewed structures in the FRAM diagrams) the visualization must be subjected to usability testing to determine whether the design criteria have been achieved and the solutions of design problems are satisfactory. The redesigned visualization appears most effective when presented in an interactive format. It often requires multiple optimized static views to satisfactorily support browsing both in overview and in detail.</p><p> </p>

Une carotte sédimentaire, couvrant les derniers 2500 ans, a été échantillonnée sur la marge continentale Ouest du Spitzberg dans le détroit de Fram (78,92°N 6,77°E, profondeur d'eau: 1497 m) avec pour objectif de reconstituer les variations hydroclimatiques à partir de l'analyse des assemblages de dinokystes. L'abondance relative des taxons de dinokystes ainsi qu'une analyse en composantes principales permet de distinguer une période de transition majeure à 300 ans cal. BP. Celle-ci est marquée par la disparition simultanée des taxons thermophiles Spiniferites mirabilis-hyperacanthus et Impagidinium sphaericum ainsi qu'une augmentation des taxons polaires-subpolaires Impagidinium pallidum et Pentapharsodinium dalei. Les températures de surface estimées suggèrent des conditions plus chaudes que celles de l'actuel (moyenne de 7°C en Été, soit une anomalie d'environ +2°C) jusqu'à 300 ans cal. BP malgré plusieurs phases de refroidissement vers 1700, 1500, 1200 et 800 ans cal. BP. Les derniers 300 ans se caractérisent par une tendance au refroidissement, avec des températures d'Été chutant de 7,6 à 3,5°C et un couvert de glace de mer atteignant 7 mois/an. Les résultats obtenus montrent que le couvert de glace de mer et la température de surface océanique dans la région du détroit de Fram sont sensibles aux variations hydroclimatiques, principalement liées au débit relatif des eaux chaudes et salées du courant Nord Atlantique pénétrant à l'Est et des eaux froides et déssalées sortant de l'Arctique, à l'Ouest. Nos données mettent également en évidence un optimum thermique vers 1320 ans cal. BP qui représenterait le seul intervalle des derniers 2500 ans pouvant être un analogue des conditions modernes post-AD 2000 et se singularisant par une absence du couvert de glace de mer. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Holocène, Mers nordiques, Détroit de Fram, Conditions océaniques de surface, Dinokyste.

The Functional Resonance Accident Model is a method developed to analyze complex systems for the purpose of accident prevention. In FRAM-analysis a visualization of the complex system is created as an aid for identifying points of interaction in the system where the risk of accidents is high, and to determine where preventive measures are to be placed. FRAM Visualizer is a computer program developed as a tool for creating such visualizations. Many usability problems have been identified in FRAM visualizations created both manually according to established method and by using the FRAM Visualizer software. The purpose of this paper is to give a basis for how FRAM visualizations can be improved in accordance with usability criteria for use in future qualitative studies. The author suggests alterations to the FRAM visualization to resolve usability issues identified in previous articles and to achieve usability goals derived from visual communication theory. The design process is guided by established design principles. The author outlines a proposal for usability testing of the redesigned FRAM visualization to verify that it achieves the usability goals. The author concludes that though the redesign offers solutions for the most important problems (providing the user with detailed information as a basis for analysis and enabling the layout of clearer and more easily overviewed structures in the FRAM diagrams) the visualization must be subjected to usability testing to determine whether the design criteria have been achieved and the solutions of design problems are satisfactory. The redesigned visualization appears most effective when presented in an interactive format. It often requires multiple optimized static views to satisfactorily support browsing both in overview and in detail.

Zugl.: Aachen, Techn. Hochsch., Diss., 2007.

Techn. Hochsch., Diss., 2003--Aachen.