Abstract
In this paper, effects of capping layers on formation and electrical properties of Ni-silicided junctions have been investigated. Nickel silicide films using the Ti or TiN-capped layer process are used to compare to those by the uncapped process. The uncapped (Ni single layer) and TiN-capped samples are shown to exhibit better thermal stability than the Ti-capped samples. For the silicided junctions, samples using Ti capping layer processes exhibit larger leakage current densities. A high-resistivity Ni x Ti y Si z compound layer is formed on the surface during silicidation for the Ti-capped sample, while the uncapped and TiN-capped samples are not. In addition, it is found that the thickness of NiSi layer, as well as the Ni x Ti y Si z layer, increases with increasing the Ti capping layer thickness. The formation of Ni x Ti y Si z layer not only increases the contact resistance, but also deepens the silicide thickness. © 2007 Elsevier B.V. All rights reserved.