In Situ Analysis of Copper Microstructures in Electromigration Using SEM-EBSD Techniques

Abstract

The continuing drive to miniaturise electronic devices requires an understanding of how the materials in these devices behave under stress, particularly with respect to electromigration. In this study, we explore the relationship between the microstructure of copper (Cu) and electromigration by using an approach that combines in situ Scanning Electron Microscopy (SEM) with Electron Backscatter Diffraction (EBSD). This in-situ SEM-EBSD technique enables real-time observation and analysis of electromigration-induced microstructure changes. Our investigation provides detailed insights into the microstructure effect on electromigration. Specifically, samples annealed at 300 °C showed void formation after the electromigration test and higher Kernal average misorientation (KAM) values, indicating higher internal strains and an inhomogeneous microstructure. In contrast, samples annealed at 500 °C maintained lower KAM values with minimal changes in crystal orientation, highlighting a more stable and uniform electromigration-resistant microstructure. Our results demonstrate the critical role of microstructure in determining the electromigration resistance of copper interconnects. By optimizing the annealing temperature, the reliability of the copper microstructure can be significantly improved by reducing the dislocations and increasing grain size, thus extending its lifetime.