Chemical and thermal stability of titanium disilicide contacts on silicon

The suitability of titanium disilicide (TiSi2) contacts for use in electron ic transport measurements on chemically modified Si(100) and Si(111) surfac es prepared in ultrahigh vacuum (UHV) or via wet chemical approaches has be en examined. Rapid thermal annealing at 900 degreesC of patterned Ti lines was used to produce the C54 phase of TiSi2. Atomic force microscopy, UHV sc anning tunneling microscopy, and resistivity measurements were used to char acterize the TiSi2/Si system through different stages of the disilicide for mation and subsequent high temperature annealing or wet chemical cleaning a nd etching. The contacts were found to maintain their integrity after annea ling up to 1200 degreesC or 10 min etching in 40% ammonium fluoride (NH4F). Under these preparation conditions, the silicon surface in the immediate v icinity of the TiSi2 interface remains free from major defects, thus making titanium disilicide a particularly suitable material for constructing plat forms for measurements of electrical transport of silicon surfaces as well as nanostructures fabricated on these surfaces. (C) 2001 American Institute of Physics.