Improved Interconnect Properties For Nano‐Twinned Copper: Microstructure And Stability

The presence of a large amount of nano‐scale twin boundaries in ultra‐fine grained copper has been shown to greatly improve the mechanical strength and yet to maintain a, high ductility and good electrical conductivity. Nanotwinned copper thus is promising in applications as interconnect materials. While the microstructure of nanotwinned copper is of importance to better understand the nucleation and formation mechanism of twin boundaries, the stability of twin boundaries are of equivalent critical concern since they are stacking faults in copper grains. The effect of Cu nanotwin boundaries on grain growth was observed by various characterization techniques. We found that Cu with many twin boundaries underwent weak grain growth and less abnormal grain growth compared to Cu with few twin boundaries. Stability of {111} and {112} twin boundaries have been studied respectively under thermal aging and current stressing. The driving force of the twin boundary motion has been investigated to help understand micr...