Ellipsometric measurements of the CoSi2 formation from very thin cobalt films on silicon

Abstract
Thin CoSi2 films (2 from CoSi was followed by the use of ellipsometry. Mixed phases of CoSi and CoSi2 were created at temperatures of 600, 625, 650, and 675 °C. The ellipsometric response of these samples were simulated using a model of two layers of silicide on a silicon substrate. The refractive indices of CoSi and CoSi2 were measured separately and were found to be 3.2+i2.44 and 2.2+i1.34, respectively. The analyses of the data indicate that the phase transformation from CoSi to CoSi2 is diffusion controlled and the activation energy of the reaction in this temperature range is 1.78 eV.