In Situ Electron Diffraction and Resistivity Characterization of Solid State Reaction Process in Cu/Al Bilayer Thin Films

Solid state reaction processes in Cu/Al thin films have been studied using the methods of in situ electron diffraction and electrical resistivity measurements. The solid state reaction in the Cu/Al thin films has been found to begin already at 88 °C with the formation of the Al 2 Cu phase in the process of thermal heating in vacuum. The phase sequence at the solid state reaction in the films under study has been determined to be the following: Al 2 Cu → AlCu → Al 4 Cu 9 . A model has been suggested for describing the initial formation stage of intermetallic compounds at the solid state reaction in Cu/Al thin films. According to this model, at the initial stage, the intermetallic compounds are formed as separate crystallites at the interface in the Cu/Al thin films. The suggested model can be applied both to the formation of the first phase, Al 2 Cu, and to the subsequent phases: AlCu and Al 4 Cu 9 . For the Al 4 Cu 9 phase the temperature coefficient of the electrical resistivity has been determined to be equal to α Al 4 Cu 9 = 1.1 × 10 −3 K −1 .