Electrodeposition of porous silver films on blanket and patterned aluminum-copper films

As an alternative to the zincate process, aluminum-copper (Al-Cu) films are made amenable for metallization by anodization and chemical etching of aluminum oxide. Electrodeposition of silver on anodized and etched Al-Cu films proceeds with the formation of a porous network composed of electrically interconnected nanoparticles of silver. The mean particle diameter is 30 +/- 7 nm. The frequency response of the porous network is evaluated by electrochemical impedance spectroscopy using the transmission line model. The capacitance normalized to the geometric electrode area and the gravimetric capacitance are 2.9 +/- 0.1 mF/cm(2) and 3.9 +/- 0.1 F/g, respectively. The electrolyte-accessible area of electrodeposited nanoparticles is 20 m(2)/g. The proposed procedure for electrodeposition on anodized and etched Al-Cu films is compatible with photolithographic techniques. Electrodeposition on patterned Al-Cu films is achieved by transferring the plating mask from a photoresist to a layer of barrier aluminum oxide.