Co films with various thicknesses were selectively deposited as Cu capping layers by chemical vapor deposition. Both in situ and ex situ Co/SiC(N,H) capping processes were evaluated and have shown comparable parametrics to the control reference. For the ex situ capping process, the degree of electromigration (EM) resistance enhancement was observed to be dependent on the deposited Co thickness. Without increasing the Co cap thickness, further EM lifetime enhancement was observed from the in situ capping process. © 2012 IEEE.