A ternary compound ofCo3Ti2Siis suggested as a reaction barrier for the formation of epitaxialCoSi2in the Co/Ti/Si system when adopting the rapid thermal annealing process. It controls Co diffusion to the Si substrate, followed by formation of epitaxialCoSi2. After the epitaxialCoSi2was formed, the interfacial morphology of the upper layer/CoSi2interface 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 theCoSi2layer 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 thep+njunction diode. ©1997 American Institute of Physics.