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

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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.