30 Years of electroless plating for semiconductor and polymer micro-systems

Electroless deposition (ELD) is a well-known method for preparing thin films of metals and their alloys. It is a highly selective method allowing additive patterning of isolated and embedded structures on insulating substrates, e.g. glass, plastic or ceramic. It is a relatively low temperature (less than the boiling point of the electrolyte) and low cost process compared to other physical and chemical vapor deposition methods. ELD features uniform and normally conformal deposition (additives may affect its conformality) with low defect density and some unique material properties. In the last 30 years electroless plating of metals (e.g. copper, gold, nickel, cobalt, palladium, iron, silver, etc.) and their alloys, was demonstrated for micro system applications: microelectronics, micro electro mechanics, micro electro optics and microfluidics, micro fuel cells, micro batteries etc. Electroless plating was also demonstrated on nano structures, both artificial and natural. In this paper we present a short tribute to the recent advances in electroless plating in the last 30 years. Those advances and innovations are due to the work of many scientists and engineers on a time span started in the 19th century. The progress in electroless plating followed the need and the trend for better metallization technologies for complex structures with critical dimensions that had been shrinking continuously in the last few decades.