| Abstract
| - A low-temperature CO2-based technology, supercritical fluid immersion deposition (SFID),has been developed for producing Pd, Cu, Ag, or other metal films on Si-based substrates insupercritical CO2 solutions. The reaction is most likely initiated by oxidation of elementalsilicon to SiF4 or H2SiF6 with HF, causing the reduction of a metal chelate precursor to themetallic form on silicon surface in CO2. Using this method, only the substrate surfacesexposed to CO2 solutions are coated with metals, and the metal films (Pd, Cu, and Ag) exhibitgood coverage, smooth and dense texture, and high purity. Preliminary experiment indicatesthat palladium films deposited on silicon by SFID can be converted to palladium silicide byannealing treatment. Metal films can also be deposited onto germanium substrates usingSFID. The gaslike properties and high pressure of the supercritical fluids, combined withthe low reaction temperature, make this SFID method potentially useful for fabricating thinfilms of metal or metal silicide in small features, which is difficult to accomplish byconventional metal deposition methods.
- Thin metal films (Pd, Cu, and Ag) are deposited onto Si and Ge substrates, or into small features of silicon testing wafers through redox reactions between Si or Ge and supercritical CO2 solutions containing metal precursors and HF. The deposition occurs only on surfaces exposed and reactive to CO2 solutions. This supercritical fluid immersion deposition method is potentially useful for fabricating thin films of metals or metal silicides in small features.
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