GROWTH AND STRUCTURE OF TITANIUM SILICIDE PHASES FORMED BY THIN TI FILMS ON SI CRYSTALS

The silicide formation with a titanium film deposited on ?100? single-crystal silicon, has been studied by using nuclear microanalysis, x-ray diffraction, and transmission electron microscopy. The presence of interfacial defects and their possible role in the early stages of the reaction has been evidenced. The phase composition was dependent on the annealing temperature and time: at 550 °C only TiSi2 is observed; at higher temperatures (>600 °C), a thin TiSi2 layer at the interface is again observed, but Ti-rich silicides grow on top of this layer by increasing the annealing time. For longer annealing times, all the reacted layer progressively transforms into TiSi2. The amount of reacted silicon grows with a (time)1/2 law; the activation energy of 1.8 eV reported for the growth of TiSi2 onto amorphous Si may be appropriate even in this case. The reaction proceeds at a rate of one order of magnitude higher than previously reported for reaction between silicon and an oxygen saturated titanium film. The kinetics seems to be controlled by silicon diffusion through the TiSi2 interfacial layer.