Growth kinetics of Pd 2Si from evaporated and sputter-deposited films

Abstract

The growth kinetics of Pd 2Si formed by palladium films either vacuum deposited or sputter deposited onto vacuum-evaporated, sputter-deposited or single-crystal silicon substrates were investigated by backscattering spectrometry (BS). The impurity contents of the films and substrates were characterized by both secondary ion mass spectrometry and BS. In all cases, Pd 2Si is the only silicide phase detected after vacuum annealing up to 300°C and the growth mechanism is always diffusion limited. The rate of the diffusion was found to differ and the activation energies for Pd 2Si formation varied between 0.9 and 1.5 eV. These changes are correlated with the presence of impurities in the deposited palladium and silicon films. Also, sputtered palladium films do not form epitaxial Pd 2Si layers on (111) Si substrates as vacuum-deposited palladium films do. The conclusion is that rates of reaction and morphology of Pd 2Si layers grown by thermal annealing depend on the deposition system.