Stresses during silicide formation: A review

According to published results, the stresses that develop during suicide formation by metal-silicon reaction arc generally compressive. Some data, however, indicate tensile stresses during the formation of some silicides. It is possible that the reversal in the stress sign is due to the effect of impurities, however, the case for such an effect is not entirely convincing. Clearly the presence of compressive stresses show that the overall volume decrease that accompanies silicide formation does not play a significant role in stress development. A model, that takes into account the simultaneous stress formation due to the reaction and the relaxation of these stresses, provides a qualitatively satisfying picture of stress evolution. However, the model is not really quantitative because the relaxation law used is not physically correct. In the absence of enough reliable data and of a physically correct model one is limited to conjectures of a very general nature. Epitaxy should be considered as a factor determining the sign of the observed stresses.