Comparison of thin film cracking and delamination for aluminum and copper silicon interconnects with organic packaging

Silicon passivation cracking and interconnect metal thin film cracking and delamination are organic packaging failure modes that result from the global thermal expansion mismatch between the package and silicon plus local thermal expansion mismatch among various silicon build up interconnect metal and passivation materials. The risk of these two failure modes is different between aluminum and copper silicon interconnects. Modeling and experimental data suggest the risk of silicon passivation film cracking and delamination is no longer a major reliability issue as it was in the aluminum interconnect technologies, due to the planar surface topography in copper damascene and the lower coefficient of thermal expansion.