Deposition of ru thin films from supercritical carbon dioxide fluids

Ruthenium has been of interest for application in ULSI capacitor electrodes and more recently as a barrier metal against Cu diffusion. Thin-film deposition from supercritical CO2 has gained particular attention as a new deposition technique that provides nano-penetration capability and a possibility of developing new deposition chemistries. However, few papers have been published on this technique. In this article, first, the deposition characteristics of Ru thin films using H-2 reduction chemistry were described. It was found that Ru films grow only on conductive surfaces when H-2 reduction chemistry was employed. These films can be beneficial for some specific applications; however they are not very much favored for general deposition technology. Second, we report that Ru films, oxygen-containing Ru films in fact, grew on dielectric/nonconductive surfaces when oxidative chemistry was used. O-3 was used as an oxidant for thin film deposition from supercritical fluids for the first time. The use of O-3 promotes heterogenous nucleation and increases the amount of oxygen in the films. Oxygen-containing Ru was reduced by another reduction run using supercritical CO2.