Growth of titanium silicide on ion-implanted silicon

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Abstract
Silicon samples implanted with high doses of 121Sb, 75As, 31P, 16O, and 40Ar prior to Ti evaporation were studied to measure the growth of Ti‐silicide layers. The annealing behavior of these samples was investigated by four‐point probe measurement, Rutherford backscattering, and by x‐ray diffraction. The samples implanted with Sb, As, and P atoms enabled the growth of TiSi2 to be observed, though its final thickness was less than half when compared to that of the nonimplanted samples. Simultaneously with the diffusing‐out atoms of Sb, during annealing, segregation of Sb atoms takes place at the TiSi2/Ti interface and at the Ti surface. Using a simple model for the out‐diffusion of Sb atoms, the activation energy of the diffusion coefficient of Sb in the Ti silicide was determined, giving a value of Ea=1.9 eV. During out‐diffusion, As atoms tend to be distributed homogeneously in the silicide layer. With Ar‐ and O‐implanted samples, precipitation of Ti atoms can be observed at the implantation depth, and at higher annealing temperatures, the metal layer flakes off the sample. A simple model is given to explain this behavior. X‐ray diffraction measurements of these samples showed the presence of the unstable TiSi phase, but no trace of the TiSi2 phase was found after annealing at 700 °C.