Chemical and thermal stability of titanium disilicide contacts on silicon

Abstract

The suitability of titanium disilicide (TiSi2) contacts for use in electronic transport measurements on chemically modified Si(100) and Si(111) surfaces prepared in ultrahigh vacuum (UHV) or via wet chemical approaches has been examined. Rapid thermal annealing at 900 °C of patterned Ti lines was used to produce the C54 phase of TiSi2. Atomic force microscopy, UHV scanning tunneling microscopy, and resistivity measurements were used to characterize the TiSi2/Si system through different stages of the disilicide formation and subsequent high temperature annealing or wet chemical cleaning and etching. The contacts were found to maintain their integrity after annealing up to 1200 °C or 10 min etching in 40% ammonium fluoride (NH4F). Under these preparation conditions, the silicon surface in the immediate vicinity of the TiSi2 interface remains free from major defects, thus making titanium disilicide a particularly suitable material for constructing platforms for measurements of electrical transport of silicon surfaces as well as nanostructures fabricated on these surfaces.