Nano-porous gold interconnect

Nanoporous gold has been deposited on silicon wafers by electroplating a silver-gold alloy followed by etching the silver. An open-porous cellular structure of gold at nano- or meso-scale is left. Nanoporous bumps were formed, which have been used for flip chip bonding. We found low temperature and low force bonding conditions which are similar to sintering. The porous interconnects show very promising properties, like compressibility and reduced stiffness, which should result in higher bond yield and extended reliability. Keywords: bumping, flip chip, nano-sponge, cellular structure, sintering.