In situ electron microscopy studies of electromigration in stacked Al(Cu)/TiN interconnects

In situ transmission electron microscopy experiments on electromigration in Al(0.5%Cu)/TiN interconnects show that the TiN barrier layer improves reliability not only by acting as a shunting layer, but also by dramatically influencing electromigration behavior within the Al(Cu) interlayer. One highlight of these experiments is a complete absence of void migration in such lines, as opposed to Al(Cu) lines on ${\mathrm{SiO}}_{\mathrm{2}}$ without barrier layer $[{\mathrm{Al(Cu)/SiO}}_{\mathrm{2}}\mathrm{].}$ This remarkable immobility of voids in Al(Cu)/TiN lines has a profound impact on failure mechanisms, lifetimes, and reliability of interconnects. The TiN barrier layer also dramatically effects void nucleation and growth.