Preparation of ultrathin TiNx films by radical assisted low temperature deposition and their barrier properties against Cu diffusion

We examine characterization and barrier properties of the TiNx films prepared by an original deposition method, which consists of conventional sputtering and radical treatment. This method realizes the low-temperature deposition of the diffusion barriers applicable to Cu-through silicon via (TSV) in the three-dimensional large scale integration (3D-LSI) of wafer on wafer process. We can successfully prepare the TiNx films of low resistivity and high density at a temperature lower than 200 °C. The 5-nm-thick TiNx films as the diffusion barrier for Cu-TSV show sufficient performance to the thermal stress without interface layers owing to solid-phase reaction and intermixing after annealing at 500 °C for 30 min at both Cu/TiNx and TiNx/SiO2 interfaces. The proposed method in this study is a candidate process for depositing the transition metal nitride film at low temperatures in the 3D-LSI.