Electrical property-microstructure of copper interconnects printed by localized pulsed electrodeposition (l-PED)

Abstract

Printing processes that enable printing high conductivity metals at small scale (<mm) are in demand for microelectronics, interconnects, and sensors applications. Since electrical properties of metals are controlled by their microstructure, microstructure-property relation for each process needs to be established. In the recently developed localized pulsed electrodeposition (l-PED) process, the pulsed voltage applied during metal printing allows control over the microstructure. In this article, we quantify the electrical resistivity of copper (Cu) interconnects printed by the l-PED process and correlate it with its microstructure. The results show a microstructure combined of nanotwinned (nt) grains and nanocrystalline (nc) grains, with an average grain size of 190 nm and twin thickness of ∼8 nm to ∼29 nm. The electrical resistivity was measured to be 8.25 µΩ.cm, which correlates with the observed microstructure and is remarkable for a printing process with no post-processing annealing done on the printed metal.