Nanoscale Analysis of Multilayer Interfaces of W/Al2O3/Ti/Cu

W, Al₂O₃ and Ti films were deposited onto a Cu substrate by means of the rf magnetron sputtering method. After deposition, the foils were annealed at various temperatures in vacuum and the interfaces of the films were observed by a field-emission transmission electron microscopy (FE-TEM), after preparing a cross-sectional thin foil using a focused ion beam (FIB) machine. After annealing the foil at 473 and 623 K, no reaction phases were identified at each interface of W/Al₂O₃, Al₂O₃/Ti and Ti/Cu-substrate. However, from the results of compositional analysis at the interface of Al₂O₃/Ti bilayer, after heat-treatment at 623 K, the formation of an oxide layer was suggested even though it was not clearly observed. On the other hand, after heat-treatment at 823 K, the formation of CuTi₂, Cu₃Ti₂ and Cu₄Ti phases were identified at the interface of Ti/Cu bilayers from the compositional analysis of reaction layers after heat-treatment at different temperatures, and the diffusion coefficients and activation energies in the phases were evaluated. In this paper, the influence of heat-treatment on the interfacial behavior of multilayer are discussed on the basis of nanoscale analysis by EDS and HRTEM images.