Transmission electron microscopic in situ experiments on Al-0.5%Cu/TiN interconnects showed that the TiN barrier-layer improved reliability by acting as a shunting layer and by markedly affecting the electromigration behavior within the Al-Cu interlayer. An interesting aspect of the experiments was the complete absence of void migration in these lines; as compared to Al-Cu lines on SiO2 without a barrier layer. The marked immobility of voids in the Al-Cu/TiN lines had a great impact on the failure mechanisms, lifetimes and reliability of interconnects. The TiN barrier layer also markedly affected void nucleation and growth.

in situ Electron Microscopy Studies of Electromigration in Stacked Al(Cu)/TiN Interconnects. J.T.Lau, J.A.Prybyla, S.K.Theiss: Applied Physics Letters, 2000, 76[2], 164-6