Room temperature electroless plating copper seed layer process for damascene interlevel metal structures

Described in this paper is the development of a room temperature electroless copper seed layer deposition process on ultra-thin TiN barrier layers. This novel process is compatible with damascene interlevel metal structures for sub-0.18 micron ULSI processes. An optimum copper layer thickness of 50 nm and a deposition rate of 45 nm min⁻¹ was targeted and obtained. Atomic force microscopy (AFM) reveals that the non-uniformity of the seed layer is less than 10% of the film thickness, while four-point probe measurements indicate that the resistivity of the copper seed layer is less than 6 μΩ cm⁻¹. Secondary ion mass spectroscopy (SIMS) reveals that potential metallic contaminants such as sodium, potassium, calcium and magnesium ions do not penetrate the TiN barrier layer. Rutherford back scattering (RBS) indicates that the palladium concentration in the seed layer is approximately 1%, which is low enough to avoid wafer contamination and increased resistivity in the subsequent electroplated copper layer.     

Oxidation behavior of atomized Fe40Al intermetallics doped with boron and reinforced with alumina fibers

Isothermal oxidation resistance of Fe40 (at.%) Al-based atomized and deposited intermetallic alloys has been evaluated. The alloys included Fe40Al, Fe40Al + 0.1B, and Fe40Al + 0.1B + 10Al₂O₃ at 800, 900, 1000, and 1100 °C. The tests lasted approximately 100 h, although in most cases there was scale spalling. At 800 and 900 °C, the Fe40Al + 0.1B alloy had the lowest weight gain, whereas the Fe40Al alloy had the highest weight gain at 800 °C (0.10 mg/cm²) and the Fe40Al + 0.1B + 10Al₂O₃ alloy was the least oxidation resistant at 900 °C with 0.20 mg/cm². At 1000 °C, the Fe40Al + 0.1B alloy showed the highest weight gain with 0.12 mg/cm² and the Fe40Al alloy the lowest. At 1100 °C, again, as at 900 °C, the Fe40Al alloy was the least resistant, whereas the Fe40Al + 0.1B alloy performed the best, but the three alloys exhibited a paralinear bahavior on the weight-gain curves, indicating the spalling, breaking down, and rehealing of the oxides. This spalling was related to voids formed at the metal-oxide interface.     

A Reinterpretation of Beall’s ‘Off-Topic’ Semantics

Journal of Logic, Language and Information - Jc Beall’s off-topic interpretation of Weak Kleene logic offers a logic of ‘true-and-topic’ preservation. However, Nissim Francez has...     

Formula zero: Development and kart’s competition driven by PEM fuel cell

Formula Zero (FZ) is an European project that promotes a zero emissions karts championship based on fuel cell (FC) technology. The project’s objectives are: first, to compete at FZ championship with own FC vehicle, second, to demonstrate that sustainable mobility is possible having zero emissions transports, and third, to take out all the knowledge gained during the development of this project for implanting it in future projects with FC automotive applications. The team has designed and built a kart powered by a stack of PEM 1.2 kW at a first prototype and another prototype powered by a 8 kW stack in a second stage. The goal of the project is to confirm that karts powered by hydrogen and FC are able to compete at velocity races, getting same performance as conventional karts. The difference is that the FC kart is an electric vehicle, with no emissions, no noise, and no vibrations.     

Automatic correction of background phase offset in 4D-flow of great vessels and of the heart in MRI using a third-order surface model

Magnetic Resonance Materials in Physics, Biology and Medicine - To evaluate an automatic correction method for velocity offset errors in cardiac 4D-flow acquisitions. Velocity offset correction was...     

Ca and K decorated germanene as hydrogen storage: An ab initio study

The hydrogen storage capacity and performance of Ca and K decorated germanene were studied using density functional theory calculation. The Ca and K adatoms were found to be sufficiently bonded to the germanene without clustering at the hollow site. Further investigation has shown an ionic bonding is apparent based on the charge density difference and Bader charge analysis. Upon adsorption of H₂ on the decorated germanene, it was found that the Ca and K decorated systems could adsorb 8 and 9 H₂ molecules, respectively. The adsorption energies of H₂ molecules were within the Van der Waals energy (400–435 meV), suggesting weak physisorption. The charge density profile revealed that the electron of H₂ moved toward the adatom decoration without leaving the local region of H₂. This suggests that a dipole-dipole interaction was apparent and consistent with the energy range found. Finally, the gravimetric density obtained from the adsorption of H₂ on the decorated germanene shows that this material is a potential for H₂ storage media.     

Growth ofStaphylococcus aureus and synthesis of enterotoxins in home-made yoghurt

Summary Staphylococcus aureus strains FRI-100, S6, FRI-137 and FRI 472 were inoculated into milk to study growth and enterotoxin production in homemade yogurts. The yogurt used as starter was progressively weakened by successive inoculations (up to four) in milk to prepare other yogurts in order to study the ability of yogurt microflora to inhibit staphylococci. After elaboration, yogurts were stored at 4 °C, 22 °C, and 37 °C for a maximum of 21 days. Periodically, staphylococcal counts, pH and the production of enterotoxins A, B, C, and D were determined. Enterotoxins were only detected in the last batch. It was concluded that the inhibitory effect of the starter culture is not only due to the decrease of pH, but also to other factors.

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Wachstum vonStaphylococcus aureus und Synthese von Enterotoxinen in hausgemachtem Joghurt

Zusammenfassung Stämme vonStaphylococcus aureus wurden in Milch überimpft, um ihr Wachstum und die Enterotoxin-Produktion zu studieren. Der als Joghurt verwendete Starter war durch die fortlaufende Überimpfung (bis zu viermal) in Milch geschwächt, um damit Joghurt herzustellen und seine Fähigkeit zu studieren, Staphylokokken zu hemmen. Nach der Entwicklung wurden die Joghurtproben für 21 Tage bei 4 °C, 22 °C und 37 °C aufbewahrt. Periodisch wurde die Zahl der Staphylokokken, der pH-Wert und die Produktion der Enterotoxine A, B, C und D bestimmt, die allerdings nur in der letzten Partie nachgewiesen wurden konnten. Daraus wurde geschlossen, daß der Hemmeffekt des Starters nicht nur auf die Abnahme des pH-Wertes zuriickzufiihren ist, sondern auch auf andere Faktoren.

     

Determination and risk assessment of by-products resulting from photocatalytic oxidation of toluene

The generation of harmful by-products during photocatalytic oxidation (PCO) of volatile organic compounds (VOCs) is a bottleneck problem for the application of PCO technology in indoor environment. Toluene is a typical VOC found in indoor air. In this work, the by-products at ppb level were studied during PCO decomposition of toluene in a plate-type reactor and identified using PTR-MS (proton transfer reaction-mass spectrometry) and GC–MS (gas chromatography–mass spectroscopy). The results indicated that benzaldehyde, methanol, acetaldehyde, acetone/propionaldehyde, formic acid/ethanol and acetic acid were the main by-products in the gas phase. By adjusting the concentration of water vapor, some compounds adsorbed on the TiO₂ surface were ascertained, which resulted in the deactivation of TiO₂. They were benzoic acid, benzene, acrylaldehyde, butyraldehyde and pentanal. Some of these by-products have not been reported in the literature. Possible photocatalytic oxidation pathways of toluene were proposed. A health-related index (HRI) was introduced to assess the risk level to human health of these ppb-level by-products. It concludes that although some undesired by-products (even carcinogenic) are generated during PCO decomposition of toluene, it seems that these by-products do not have negative effects to human health because of their low concentrations.     

Case Study: Impact of Reservoir Stratification on Interflow Travel Time

A case study is presented on the relation between interflow travel time and reservoir stratification. A simulation model is calibrated and validated for the Wachusett Reservoir in Massachusetts. The Reservoir has a major controlled inflow which traverses the reservoir as an interflow. The model is used with a range of alternate inflow schedules and the resulting travel time of the interflow is examined. The inflow density is within the range of densities found in the reservoir thermocline and the inflow rate is sufficient to maintain a continuous interflow. Under these conditions it is found that a linear relation exists between the average interflow travel time, as measured by the arrival of a specified fraction of interflow water at the outlet, and the degree of stratification, as measured by the maximum difference in reservoir thermocline temperature, at the initiation of the inflow. The results may be useful for operation of the reservoir under study subject to continued validation of the simulation model used.