In-situ metal/dielectric capping process for electromigration enhancement in Cu interconnects

Co films with various thicknesses were selectively deposited as Cu capping layers by a chemical vapor deposition technique. Both in-situ and ex-situ Co/SiC(N,H), metal/dielectric, capping processes were evaluated and shown comparable parametrics to the control reference, which contains only SiC(N,H) cap layer. A dependence of Cu electromigration (EM) resistance on the deposited Co thickness was observed from the ex-situ capping process. Without increasing the Co cap thickness, further EM lifetime enhancement was achieved from the in-situ capping process. Selectivity of the Co metal deposition was also confirmed with time-dependent dielectric breakdown test results.