Microstructural characterization of copper metallic deposition by electroplating growth for SIP applications

Abstract

Microstructural characterization (Focused Ion Beam and Transmission ElectronMicroscopy imaging) was performed on cross-sections of contacts in thick Electro Chemical Deposition copper metallization of System In Package Integrated Circuits. It was shown that the lower growth rate of ECD-Cu in the AlSiCu -barrier Ti -PVD-Cu -ECD-Cu layer stacking is related to a local higher resistivity induced by the presence of a great number of almost planar grain boundaries in the PVD-Cu layer, which are perpendicular to the growth axis. This morphology is a consequence of the almost heteroepitaxial growth of Ti layer on AlSiCu layer.