Effect of a titanium cap in reducing interfacial oxides in the formation of nickel silicide

Abstract

Interfacial silicon oxide present at the Ni–Si interface hampers the silicidation between Ni and Si. In this work we present findings of the interaction of a Ti cap layer on top of Ni to remove the interfacial native oxide and chemically grown silicon oxide at several annealing temperatures. It was found that at 500 °C, Ti diffuses through the Ni layer and segregates at the Ni/Si interface, which subsequently reduces the interfacial silicon oxide and enables nickel monosilicide (NiSi) formation at 600 °C. The thickness of the Ti cap layer was found to strongly influence the temperature of the onset of nickel silicidation. A thin Ti cap layer resulted in the onset temperature of nickel silicidation being the same as that without a Ti cap layer, whereas a thick Ti cap layer lowered the onset temperature of the nickel silicidation.