CoSi_2 formation using a Ti capping layer ― The influence of processing conditions on CoSi_2 nucleation

摘要

A reactive Ti capping layer is needed to getter oxygen contamination and to make the cobalt silicidation reaction a more robust process. However, the presence of a Ti capping layer induces two other effects (in addition to the beneficial gettering of oxygen impurities): the formation temperature of CoSi_2 is increased and the CoSi_2 layer has a strong (220) preferential orientation. Because of the current technological importance of the Ti/Co/Si system, we have made a detailed investigation of the influence of several process parameters (annealing temperature, selective etching, layer thickness) on the nucleation of CoSi_2 in the Ti/Co/Si system. Moreover, it is shown that the addition of Ni (i.e. a Ti/Co/Ni/Si or Ti/Ni/Co/Si structure) causes a decrease of the CoSi_2 nucleation temperature.