GROWTH AND OXIDATION OF THIN FILM Al_2Cu

摘要

Al_2Cu thin films (～382 nm) are fabricated by melting and resolidifying Al/Cu bilayers in the presence of a ～ 3 nm A1_2O_3 passivating layer. X-ray Photoelectron Spectroscopy (XPS) measures a 1.0 eV shift of the Cu2p_(3/2) peak and a 1.6 eV shift of the valance band relative to metallic Cu upon Al_2Cu formation. Scanning Electron Microscopy (SEM) and Electron Back-Scattered Diffraction (EBSD) show that the Al_2Cu film is composed of 30- 70 μm wide and 10-25 mm long cellular grains with (110) orientation. The atomic composition of the film as estimated by Energy Dispersive Spectroscopy (EDS) is 67+-2% Al and 33+-2% Cu. XPS scans of Al_2O_3/Al_2Cu taken before and after air exposure indicate that the upper Al_2Cu layers undergo further oxidation to A1_2O_3 even in the presence of ~5 nm A1_2O_3. The majority of Cu produced from oxidation is believed to migrate below the A1_2O_3 layers, based upon the lack of evidence for metallic Cu in the XPS scans. In contrast to Al/Cu passivated with A1_2O_3, melting/resolidifying the Al/Cu bilayer without A1_2O_3 results in phase-segragated dendritic film growth.