Observations of copper (Cu) transport in through-silicon vias (TSV) structure by electrical characterization for its reliability evaluation

摘要

Through-silicon via (TSV) has in recent years been actively pursued and has become one of the key enablers for three dimensional (3D) IC. However, one of the widely used filler material for TSV is copper (Cu), which readily diffuses into the dielectric layer. In this study, the monitoring of Cu ions transport within the dielectric layer is observed and controlled for its reliability assessment. Cu ions can be driven towards the silicon dioxide (SiO) or back to the Cu bulk by applying an appropriate E-field. Time dependent dielectric breakdown (TDDB) was then performed at various conditions and it was found that the breakdown mechanism is different, dependent on the tested, E-field and temperature where Cu ions could play different roles in the dielectric. Finally the extension of TDDB lifetime was also demonstrated with appropriate control of the Cu ions, based on the understanding of the breakdown mechanism.