Improving the integrity of Ti barrier layer in Cu-TSVs through self-formed TiSix for via-last TSV technology

Abstract

With in the process temperature limit of less than 400 °C for via last technology, a simple method to improve the barrier ability of Ti layer in through Si via (TSV) has been studied. After annealing the TSV structures in vacuum at temperatures up to 400 °C, we did observe a tremendous improvement in leak current characteristics for SiO2 dielectric. It was found that the self-formed TiSix at the interface between Cu and SiO2 during the sputter deposition of Ti barrier layer was converted into an amorphous TiOx and SiOx upon vacuum annealing. This simple vacuum annealing of Cu-TSVs is a promising approach for using Ti as barrier layer in via-last 3D-integration.