Influence of the Complexing Agents on the Thickness Uniformity of Electroless Nickel Plating in Deep-Recessed Trenches

Abstract

Electroless plating has been extensively applied to electronic devices because it provides superior throwing power and uniform film formation for complicated geometries. In this study, the formation of the conductive layer in the deep-recessed trenches using electroless Ni-B plating was investigated. Uniformity of plating films was greatly influenced by the selection of the complexing agent. Superior uniformity of Ni films in deep-recessed trenches was obtained by the electroless plating bath containing DL-malic acid. On the other hand, Ni films from a bath containing glycine were not uniformly deposited and no deposition was obtained at the bottom of deep-recessed trenches. Dependence on a selected complexing agent to the initial plating reaction was investigated by the electrochemical analysis. It is confirmed that the induction time before initiation of deposition was influenced by the complexing agent, and adsorbed Pd catalyst in the trenches was dissolved during the induction time and Ni films are not uniformly deposited by the dissolution of adsorbed Pd in the trenches if the plating bath shows the long induction time. © 2004 The Electrochemical Society. All rights reserved.