Interfacial reaction and phase formation in Pd/ZrO/Pd/TiO/Pd multilayer stack on silicon substrate: Investigated by ion beam techniques

Abstract

The influence of the annealing temperature on the stability of the multilayer stack Pd/Zr/Pd/Ti/Pd thin films system, with both Zirconium (Zr) and Titanium (Ti) layers containing oxygen (O), deposited on silicon substrate was investigated. Using the in-situ real-time Rutherford backscattering spectrometry (RBS) analysis, the multilayer stacked thin film systems were linearly heated, at a constant heating rate, from room temperature up to 600 °C and found to be stable up to ∼370 °C whereby the inter-diffusion of Palladium (Pd), from both the third and the fifth layer, towards the forth layer comprising of Ti and O in 2:1 ratio, was observed. Moreover, the Ti, from the Ti–O layer, was found to spread to low and higher channels during Pd diffusion. Above 480 °C the second reaction was observed between Pd and silicon substrate, forming a hexagon silicide phase (Pd2Si) confirmed by X-ray diffraction. The thickness of the Pd2Si layer increased with increasing temperature and its activation energy was estimated to be 2.30 eV, which is about 1.10 eV and 0.65 eV higher than the activation energy of the Pd2Si phase formation at 100 °C and 250 °C, respectively. Therefore, the activation energy of the Pd2Si phase depends on the temperature at which the phase is growing.