Surface morphology of TiSi₂ on silicon

The formation mechanisms and morphology of TiSi₂ on silicon are explored. TiSi₂ is formed on atomically clean Si(100) and Si(111) substrates by UHV deposition of titanium and in situ annealing. The TiSi₂ formation process is monitored with in situ low energy electron diffraction and Auger electron spectroscopy, and the morphology is examined with ex situ scanning electron microscopy. Titanium thickness between 50 and 400 Å were examined. The TiSi₂ formation process involves interdiffusion at temperatures less than 400°C, formation of a metastable TiSi₂ phase at about 500°C, and transformation to the stable TiSi₂ phase at about 700°C. The results show TiSi₂ island formation after annealing at between 700 and 900°C, depending on the film thickness. The low energy electron diffraction measurements showed that the exposed silicon regions exhibited reconstructed surface structures after the island formation. The island formation process is described in terms of a wetting model, and the surface energies for nucleation and island formation are related.