John Zabasajja

Metal‐Carbon Composite Materials from Fiber Precursors I . Preparation of Stainless Steel—Carbon Composite Electrodes

A novel approach to fabrication of composite metal-carbon electrodes has been developed. Stainless steel fibers and carbon fiber bundles were combined with cellulose into an interwoven paper preform. The composite paper preform was then sintered to a stainless foll substrate to form the electrode structure

Modeling and Characterization of Tungsten Chemical and Mechanical Polishing Processes

Due to the complexity of chemical mechanical polishing (CMP) in general and metal CMP in particular, modeling of CMP processes has been pursued only minimally in the literature. A fundamental understanding of these metal CMP processes is needed to minimize manufacturing and development costs that will continue to escalate as more devices migrate to subhalf-micrometer technologies where metallization schemes are more complicated. In this work, we have used two different models to characterize the tungsten CMP process. While the chemical Preston model is used to explain the effect of process parameters on the mean polish rate, the slurry transport model is useful in explaining the within wafer uniformity for the polishing process. We successfully validated the chemical Preston model using design of experiment (DOE) data and demonstrated the importance of slurry transport and the pad to wafer gap, to the within wafer uniformity for the embossed and regular politex polishing pads. We showed that better uniformity is obtained throughout the wafer with the embossed politex than the regular politex pad due to the presence of grooves in the embossed pad, which allow for better slurry transport across the pad. We effectively characterized the process and studied the effects of changing the various tool and process parameters on process performance.

Metal-carbon composite electrodes from fiber precursors (for secondary cells)

The authors present an approach to the fabrication of metal-carbon composite electrodes. Stainless steel fibers (<or=2 mu m in diameter) and carbon fiber bundles (20 mu m in diameter) are combined with cellulose (as the binding agent) into an interwoven paper preform. The composite paper preform is then sintered to a stainless steel foil substrate to form the electrode structure. Composite electrode structures are characterized using scanning electron microscopy and electrochemical and kinetic measurements. The results demonstrate the versatility of the fabrication process of these composite electrodes for high-energy-density applications.<<ETX>>