Copper electroplating technology for microvia filling

This paper describes a copper electroplating enabling technology for filling microvias. Driven by the need for faster, smaller and higher performance communication and electronic devices, sequential build up (SBU) technology has been adopted as a viable multilayer printed circuit manufacturing technology. Increased wiring density, reduced line widths, smaller through-holes and microvias are all attributes of these high density interconnect (HDI) packages. Filling the microvias with conductive material allows the use of stacked vias and via in pad designs. Other potential design attributes include thermal management enhancement and benefits for high frequency circuitry. Electrodeposited copper can be utilized for filling microvias and provides potential advantages over alternative via plugging techniques. The features, development, scale up and results of direct current (DC) and periodic pulse reverse (PPR) acid copper via filling processes, including chemistry and equipment, are described.