A Model for Interdiffusion at Metal Semiconductor Interfaces: Conditions for Spiking

Abstract

ABSTRACTWe have derived a dynamical model for interdiffusion at aluminum-silicon interfaces which can explain the great variety of rates of interdiffusion observed for this system. The variables addressed by the model include the degree of covalent bonding which occurs at the chemical interface and the local atomic structure of that interface. Local solid solubility data and maximum rates of dissolution are derived analytically, and good agreement is observed between the model and both thermodynamic data for the bulk aluminum-silicon system and kinetic data for reaction rates at differently prepared interfaces. The influence of dopants and structural defects on the predictions of the model is in accord with experimental observations. The model points to some critical conditions for the preparation of thermally stable aluminum-silicon interfaces, which are potentially applicable to other metal-semiconductor systems.