Low resistance copper interconnects with MOCVD TiN(Si) barrier for sub-0.13μm applications

MOCVD TiN(Si), deposited using tetrakis(diethylamido) titanium (TDEAT) and ammonia, was evaluated as a barrier for copper damascene interconnect by testing via resistance, via chain yield, bias-temperature-stress (BTS), electromigration (EM) reliability, and electrochemical fill performance. Via chain yields were equal or better then those obtained for the PVD Ta baseline. Despite a bulk resistivity of 600 p-Q-cm the via resistance of TiN(Si) was considerably lower than the PVD reference, provided that the thickness of TiN(Si) did not exceed 75Angstrom. EELS analysis showed that CVD TiN(Si) has different nucleation characteristics on copper than on oxide ILD. A discontinuous barrier on copper accounted for the low via resistance observed. Further analysis demonstrated that the nucleation phenomenon extends to lower CVD TiN(Si) deposition temperatures. A lower deposition temperature (250degreesC) resulted in improved step coverage. The electrochemical fill experiments performed resulted in void free fill of the structures. The results obtained from BTS and EM testing on CVD TiN(Si) yielded mean time to failure that was equal or better than the PVD Ta reference.