Effects of Ti incorporation in Ni on silicidation reaction and structural/electrical properties of NiSi

The effects of Ti incorporation in a Ni film on the silicidation reaction as well as the structural and electrical properties of NiSi have been investigated. Experimental results from this work showed that the reaction-inhibiting effect of an interfacial oxide layer could be effectively overcome by Ti incorporation. It was found that, in the presence of a thin interfacial oxide (1-2 nm), the onset of the silicidation reaction occurs at 300 degreesC with a Ni(5 atom % Ti) alloy while the thin interfacial oxide effectively delays the silicidation reaction up to 700 degreesC for pure Ni. It was found that Ti reacts with the interfacial oxide, yielding an altered oxide layer, which acts as a Ni-permeable diffusion membrane during silicidation. In addition to the dramatic effect on the interfacial reaction during silicide formation, Ti incorporation was also found to improve morphological and thermal stability of NiSi. As a result, Ni(Ti)-silicided p(+)/n diodes (with/without an interfacial oxide) showed an improvement in junction integrity, as compared to pure Ni-silicided p(+)/n diodes. It is believed that the ability to form silicide effectively even in the presence of an interfacial oxide, coupled with improved junction integrity, will greatly relieve constraints on processing conditions and significantly enhance manufacturing yield. (C) 2004 The Electrochemical Society.