Analysis of solid state reactions at film/substrate interfaces by electron microscopy

Abstract

Heterogeneous thin film solid state reactions are a matter of topical interest, under both fundamental and applied aspects. The forming phases are in the nanometer size range; the structure and morphology of the involved solid/solid interfaces exerts a strong influence on the reaction kinetics and on the phase formation sequence. Thus electron microscope methods are essential, if the characteristics of film/substrate reactions are to be investigated. Results from a number of electron microscope methods, among them high-resolution and in situ TEM of cross sections, bright- and dark-field diffraction contrast TEM, energy-dispersive X-ray microanalysis and selected area electron diffraction have been used during investigations of interfacial reactions in three thin film systems: TiN/MgO, NiSi₂/Si and TiO₂/MgO. In addition to the indentification and characterization of the new phases formed, valuable information has been obtained on reaction mechanisms, interfacial kinetic reaction barriers and on the influence of stress on the phase formation.