A correlation is found between the sequence of phase formation in thin-film metal-Si interactions and the bulk equilibrium phase diagram. After formation of the first silicide phase, which generally follows the rule proposed by Walser and Bené, the next phase formed at the interface between the first phase and the remaining element (Si or metal) is the nearest congruently melting compound richer in the unreacted element. If the compounds between the first phase and the remaining element are all noncongruently melting compounds (such as peritectic or peritectoid phases), the next phase formed is that with the smallest temperature difference between the liquidus curve and the peritectic (or peritectoid) point
