Electroless Deposition: A Mechanistic Approach

Electroless deposition has a number of extremely important technological applications, most notably in the fabrication of integrated circuits. The method consists of the spontaneous reduction of a metal (for example copper or silver) from a solution of its salt, e.g. Cu(II) or Ag(I). Clearly a reducing agent - a chemical which acts as the source of the electrons - is required, but the electroless reaction is particularly useful because a surface (that acts as a catalyst to allow the deposition to proceed) is also necessary. This means that deposition is specific and, to some extent, can be controlled. The technique is used to deposit metallic coatings on various types of surface, but has become very important in recent years as a means to deposit the copper interconnects required in microelectronics (your lap-top can function because of some apparently simple, but clever, chemistry). Surprisingly, in view of its importance, the chemical fundamentals of this process are not well understood. The deceptive simplicity of the electroless process is probably the reason for this knowledge gap . Here, a novel electrochemically-based approach to probe electroless deposition is outlined. The aim of this proposal is to establish the new method as the state-of-the art technique for the determination of basic parameters relating to this important metal deposition process.