Atomic Layer Deposition of Ruthenium with TiN Interface for Sub-10 nm Advanced Interconnects beyond Copper.

Atomic layer deposition of ruthenium is studied as a barrierless metallization solution for future sub-10 nm interconnect technology nodes. We demonstrate the void-free filling in sub-10 nm wide single damascene lines using an ALD process in combination with 2.5 Å of ALD TiN interface and postdeposition annealing. At such small dimensions, the ruthenium effective resistance depends less on the scaling than that of Cu/barrier systems. Ruthenium effective resistance potentially crosses the Cu curve at 14 and 10 nm according to the semiempirical interconnect resistance model for advanced technology nodes. These extremely scaled ruthenium lines show excellent electromigration behavior. Time-dependent dielectric breakdown measurements reveal negligible ruthenium ion drift into low-κ dielectrics up to 200 °C, demonstrating that ruthenium can be used as a barrierless metallization in interconnects. These results indicate that ruthenium is highly promising as a replacement to Cu as the metallization solution for future technology nodes.

Soft, comfortable polymer dry electrodes for high quality ECG and EEG recording.

Conventional gel electrodes are widely used for biopotential measurements, despite important drawbacks such as skin irritation, long set-up time and uncomfortable removal. Recently introduced dry electrodes with rigid metal pins overcome most of these problems; however, their rigidity causes discomfort and pain. This paper presents dry electrodes offering high user comfort, since they are fabricated from EPDM rubber containing various additives for optimum conductivity, flexibility and ease of fabrication. The electrode impedance is measured on phantoms and human skin. After optimization of the polymer composition, the skin-electrode impedance is only ~10 times larger than that of gel electrodes. Therefore, these electrodes are directly capable of recording strong biopotential signals such as ECG while for low-amplitude signals such as EEG, the electrodes need to be coupled with an active circuit. EEG recordings using active polymer electrodes connected to a clinical EEG system show very promising results: alpha waves can be clearly observed when subjects close their eyes, and correlation and coherence analyses reveal high similarity between dry and gel electrode signals. Moreover, all subjects reported that our polymer electrodes did not cause discomfort. Hence, the polymer-based dry electrodes are promising alternatives to either rigid dry electrodes or conventional gel electrodes.

Effect of pore structure of nanometer scale porous films on the measured elastic modulus.

The impact of pore structure of nanoporous films on the measured elastic modulus is demonstrated for silica-based nanoporous low-k films that are fabricated using an alternative manufacturing sequence which allows a separate control of porosity and matrix properties. For this purpose, different experimental techniques for measuring the elastic properties were compared, including nanoindentation, laser-induced surface acoustic wave spectroscopy (LAwave), and ellipsometric porosimetry (EP). The link between the elastic response of these nanoporous materials and their internal pore structure was investigated using positronium annihilation lifetime spectroscopy (PALS), EP, and diffusion experiments. It is shown that the absolute value of the Berkovich indentation modulus is very sensitive to the local pore structure and stiffness of the substrate and can be influenced by densification and/or anisotropic elasticity upon indentation, while on the other hand spherical indentation results are less sensitive to the local pore structure. The comparison of Berkovich and spherical indentation results combined with finite element simulations can potentially reveal changes in the internal structure of the film. For nanoporous films with porosity above the percolation threshold, the elastic modulus results obtained with LAwave and EP agree very well with spherical indentation results. On the other hand, below the percolation threshold, the elastic modulus values determined by these techniques deviate from the spherical indentation results. This was explained in terms of specific technique related effects that appear to be sensitive to the specific arrangement and morphology of the pores.

Mechanical properties of sintered meso-porous silicon: a numerical model.

: Because of its optical and electrical properties, large surfaces, and compatibility with standard silicon processes, porous silicon is a very interesting material in photovoltaic and microelectromechanical systems technology. In some applications, porous silicon is annealed at high temperature and, consequently, the cylindrical pores that are generated by anodization or stain etching reorganize into randomly distributed closed sphere-like pores. Although the design of devices which involve this material needs an accurate evaluation of its mechanical properties, only few researchers have studied the mechanical properties of porous silicon, and no data are nowadays available on the mechanical properties of sintered porous silicon. In this work we propose a finite element model to estimate the mechanical properties of sintered meso-porous silicon. The model has been employed to study the dependence of the Young's modulus and the shear modulus (upper and lower bounds) on the porosity for porosities between 0% to 40%. Interpolation functions for the Young's modulus and shear modulus have been obtained, and the results show good agreement with the data reported for other porous media. A Monte Carlo simulation has also been employed to study the effect of the actual microstructure on the mechanical properties.

Influence of varying porogen loads and different UV cures on low-kappa film characteristics.

Nanoporous low-kappa films were manufactured by using a 3-step process: co-deposition of a skeleton and porogens by PECVD, porogen removal by remote plasma and UV cure. In this study, the influence of both the variation of the porogen load and the different types of UV-cures on several film characteristics were investigated. Improved kappa-values were observed for increased porogen to skeleton ratios and a broad band cure, where the wavelength of the photons is always higher than 200 nm. However the Young's modulus and hardness decreased correspondingly. These variations can be attributed to the changing density and chemical composition of the different films. A wide range of low-kappa films was obtained by tuning the porogen load and applying different types of UV cures.