Copper thin films were exposed to a dilute silane mixture at temperatures in the range of 190–363 °C. The resulting silicide surface layers were characterized by four-point probe, Rutherford backscattering spectrometry, and x-ray diffraction. A definitive stability regime is observed in which progressively higher copper content phases exist with increasing temperature. Cu3Si, formed in silane, on annealing converts to Cu5Si and eventually to no silicide layer by a silicon diffusion reaction that in an inert ambient drives silicon into underlying copper to form a solid solution. In oxidizing ambients, a similar phenomenon occurs but now silicon also diffuses to surfaces where it oxidizes to form a self-passivating SiO2 layer on surface. These results have important implications governing integration of copper silicide as a passivation layer and silicon hydride based dielectric deposition in copper-based multilevel interconnect in ultralarge scale integration.

This paper describes an electroless gold plating process for particulate 316L stainless steel. The process is based on a mildly acidic gold sodium thiosulfate/ascorbic acid plating solution and is performed under an inert environment at room temperature. The process affords a gold deposition efficiency of ϳ50% as inferred from a modified tin chloride based spectrophotometric assay for gold ion concentration. Successful gold deposition depended on the removal of the thin, passivating surface oxide layer on the stainless steel; this was accomplished by an initial cleaning step with 2 M HCl. In situ cyclic voltammetry experiments on a stainless steel electrode and atomic force microscopy scans on small coupons were used to further characterize the oxide removal and gold deposition reactions.

We developed electrochemical hardware and media targeted for protein chromatography. Two types of stationary phases were investigated. The first comprised gold-plated stainless 316L beads coated with a self-assembled monolayer of 6-mercaptohexan-1-ol and was expected to behave like an ion-exchange resin in the presence of an electric field. The secondary stationary phase comprised the first stationary phase with further functionalization with immobilized heme moieties and was expected to behave like immobilized metal affinity resin. We tested apparatus with both stationary phases using ribonuclease A as a model protein and applied potentials from -0.3 to +0.3 V versus the saturated calomel electrode. Despite low binding capacities, we demonstrated that protein retention on both stationary phases could be controlled with an applied potential. The greatest extent of electromodulation was achieved with the mercaptohexanol-based ion-exchange media.

To enhance the corrosion resistance and reliability of the proposed copper interconnections in silicon integrated circuits, alloying with small amounts thermodynamically favorable elements has been pursued. In the present investigation dilute copper (boron) alloy thin films (in boron concentration range of 0–4 at % in copper) were deposited by DC magnetron co-sputtering using a high purity copper and Cu-4 at. % B targets. Films were then annealed in Ar-3% H2, pure Ar, vacuum, and air ambients in the temperature range of 200–500°C. Sheet resistance, Rutherford backscattering, x-ray diffraction measurements were made to characterize the films. The residual resistivity of the as-deposited alloy films was found to be 5.3 μΩ-cm/at %. To obtain sufficiently low working resistivity, an alloy content below 0.5 at % is suggested for application as a potential metallization material. The addition of boron, which is the common dopant in Si. to the copper films offers considerable oxidation protection. The resulting oxidation rates are considerably lower than that for pure copper films. All this will be presented and discussed.