Real-time x-ray scattering study on the thermal evolution of interface roughness in COSi2 formation

Abstract

The thermal evolution of interface roughness during cobalt silicide formation in the Co/Ti/Si(001) and Co/Si(001) systems was investigated using real-time synchrotron x-ray scattering measurement. We find that the enhancement of the CoSi2/Si(001) interface roughness is caused by the retardation of silicide phase formation almost up to the CoSi2 nucleation temperature. In the Co(120 Angstrom)/Ti(50 Angstrom)/Si(001), the interface roughness increases only to 6 Angstrom during silicidation, by suppressing the reaction between the Co overlayer and Si substrate with a Ti diffusion barrier nearly up to the CoSi2 nucleation temperature of 660degreesC. In the Co(120 Angstrom)/Si(001), however, the reaction already starts at a low temperature of 300degreesC, resulting in a significant rise of the interface roughness up to 13 Angstrom, which is mainly attributed to the formation of Si{111} facets that act as the nucleation sites of misoriented CoSi2 grains. (C) 2002 American Institute of Physics.