Interfacial reaction and formation mechanism of epitaxial CoSi2 by rapid thermal annealing in Co/Ti/Si(100) system

초록

A ternary compound of Co<inf>3</inf>Ti<inf>2</inf>Si is suggested as a reaction barrier for the formation of epitaxial CoSi<inf>2</inf> in the Co/Ti/Si system when adopting the rapid thermal annealing process. It controls Co diffusion to the Si substrate, followed by formation of epitaxial CoSi<inf>2</inf>. After the epitaxial CoSi<inf>2</inf> was formed, the interfacial morphology of the upper layer/ CoSi<inf>2</inf> interface was very different according to silicidation temperature, that is, the interface was planar at 800°C, but rough at 900°C. This was attributed to the reaction between the upper layer consisting of Co-Ti-Si and the CoSi<inf>2</inf> layer at 900°C, which resulted in Ti-rich precipitates at the surface. The Ti-rich precipitates acted as a diffusion sink of dopant, thus, the leakage current density for the silicidation temperature of 900°C was much higher than that for the temperature of 800°C. These results suggest that the silicidation temperature is one of the most critical factors in determining the leakage current of the p + n junction diode. © 1997 American Institute of Physics.