Thermal stability of Al-1%Si-0.5%Cu/TiSi₂ contact structure

Abstract

Stable TiSi₂ was formed by rapid thermal annealing (RTA) on single-crystal Si. Subsequently a 600 nm-thick Al-1%Si-0.5%Cu layer was deposited on the top of the formed TiSi₂ followed by furnace annealing for 30 min at 400–600 ‡C in N₂ ambient atmosphere. The thermal stability of Al-1%Si-0.5%Cu/TiSi₂ bilayer and interfacial reaction were investigated by employing four-point probe, scanning electron microscopy (SEM) and Auger electron spectroscopy (AES). The composition and the phase of precipitates formed by the reaction of Al-1%Si-0.5%Cu with TiSi₂ were studied by energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). It was found that the TiSi₂ layer was consumed by the reaction between TiSi₂ and Al-1%Si-0.5%Cu layer, resulting in precipitates at 550 ‡C. The results from EDS revealed that the precipitates were composed of Ti, Al and Si. The precipitates were identified as Ti₇Al₅Si₁₂ ternary compound from XRD analysis.