Metal seed deposition from organic solutions for subsequent electroless plating.

摘要

A novel process for immersion metal seed layer deposition on electronic material substrates from organic solutions for subsequent electroless Cu plating is being developed. The mechanism is based on spontaneous electrochemical displacement reactions. The more noble metal is reduced and deposited on the substrate surface; simultaneously the less noble metal is oxidized and dissolved into the organic solution. The organic media used in this process are commonly used in solvent metal extraction. Compared to the conventional aqueous media, the organic solutions have very different characteristics such as poor electrical conductivity, high resistance and strong polarizing tendencies. The special properties of the organic solution result in unique deposition reactions when they are used as the immersion reaction media, providing a number of potential applications in the area of commercial plating and surface finishing.;In this study, the feasibility of using the metal seed deposition from organic method to activate various substrates for subsequent electroless Cu deposition was demonstrated. The experimental conditions, including organic solution composition, metal ion concentration, organic or aqueous additives, etching method, temperature and reaction time, were evaluated. An experimental design (DOE) was used to optimize the process parameters. Different substrates, like TiSiN and TaSiN, were evaluated for use with the organic solutions. High density and uniform metal crystal layers of Pd and Cu were successfully deposited on the substrate surface. Characterization of the deposited seed particles verified that pure metal seed crystals in a nanometer size range were present. Electroless Cu deposition was then used on the metal seed activated substrate surface to provide a continuous, adherent and shiny coating.