EPITAXIAL-GROWTH OF COSI2 ON SI(100)

Epitaxial growth of CoSi2 on Si(100) was investigated by low energy electron diffraction (LEED), UV and X-ray photoemission spectroscopy. The best quality CoSi2 layers were prepared as follows. First, equal amounts (three monolayers) of cobalt and silicon are sequentially deposited onto clean Si(100) (2 × 1) held at room temperature and subsequently annealed in the temperature range 430-650 °C. Evaporation of cobalt onto this initial template layer held at 460 °C results in continuous growth of CoSi2 up to the desired thickness. This demonstrates that silicon (or cobalt) diffusion from the substrate through the CoSi2 layer occurs readily at temperatures around 430 °C. LEED results indicate for all CoSi2 layers grown in this way a definite epitaxial relationship characterized by (100)CoSi//(100)Si with [010]CoSi//[010]Si and a reconstructed CoSi2(100) c(2 × 2) surface. It appears also that CoSi2(100) exhibits two distinct surface structures, characterized by typical photoemission spectra, either cobalt rich or silicon rich depending on the growth and annealing conditions. © 1990.