A comparative study of leakage mechanism of Co and Ni salicide processes

We investigated the leakage mechanisms of both Co and Ni salicide processes. Statistical analyses of the junction leakage and a direct light observation of the leakage points from Co and Ni salicided junctions revealed that Ni salicide also shows many localized spots that cause leakage just like those in the Co salicide case, but in the Ni salicide case, the spots are along the LOCOS edge. Leakage currents were successfully simulated by means of a new spike-leakage model that considers both area and peripheral dependent spike leakage. To explain the subsequent results, we proposed a stress induced spike growth model. Working from this model, we developed a spike-leakage-free Co salicide process using a Ge pre-amorphization step.