Ordered structures in epitaxial nickel silicide films grown on (111) silicon substrates

Abstract

Abstract The initial stages in the formation of epitaxial nickel silicide films resulting from the interdiffusion of nickel thin films (about 100 nm thick) into (111)-oriented silicon substrates have been studied using transmission electron microscopy. We report herein the formation of three ordered metastable epitaxial nickel silicide phases after short annealing treatments (about 10 min at 825 °C) that have been identified through selected-area electron diffraction, superlattice dark field imaging and X-ray microanalysis. It is argued that the observed metastable ordered phases are derivative structures of the CaF 2 structure and that these structures serve as transition phases for the formation of the cubic NiSi 2 phase.