Investigation of the oxidation kinetics of CoSi2 on (111)Si by transmission electron microscopy

Abstract

Transmission electron microscopy has been applied to study oxidation kinetics of CoSi2 on silicon for both dry and wet oxidation. Care was taken to determine the activation energies of oxidation in the temperature and time regime where the islanding of CoSi2 does not occur. For dry oxidation, activation energies for parabolic and linear growth were found to be 1.91 and 2.01 eV (±0.1 eV), respectively. For wet oxidation, activation energies for parabolic and linear growth were found to be 1.75 and 1.68 eV (±0.1 eV), respectively. The activation energy of the parabolic rate constant is substantially different from those obtained previously. The difference is attributed to the occurrence of islanding during oxidation in the previous study. A comparison of oxidation kinetics of CoSi2, NiSi2, TiSi2 on silicon with pure silicon substrates indicated that the oxidation kinetics are practically the same for CoSi2 and NiSi2 in the parabolic growth regime, but substantially different from those of TiSi2 on silicon and pure silicon. The similarity in oxidation kinetics of cubic CaF2 structure CoSi2 and NiSi2 on silicon with small mismatches to silicon is correlated to essentially the same stress level in these two silicides during the oxidation.