Electrochemical Study of the Mechanism of Ag(W) Electroless Deposition

Abstract

We present an electrochemical study of the mechanism of silver-tungsten, Ag W , thin film electroless deposition from the solutions that are used for micro-systems-metallization applications. Ag W electroless films were deposited on palladium-activated surface of thin silicon dioxide layers on silicon substrates from ammonia-acetic or benzoate silver complex basedsolutions at room temperature using hydrazine hydrate as a reducing agent. These solution compositions have been investigated.The adsorption mechanism of tungsten incorporation into Ag coating on the positively charged silver surface was proposed and its co-deposition with silver due to interfacial catalytic interaction between tungsten and silver ions in form of Ag2 W 2O7 was shown.The kinetics of the Ag W electroless deposition process was analyzed by mixed potential theory. It was shown that the anodiccharge-transfer reaction for ammonia-acetic solution and the diffusion of reduced silver ions to substrate for benzoate complexhave controlled this process.