Growth and oxidation of thin film Al2Cu

Al2Cu thin films (similar to 382 nm) are fabricated by melting and resolidi fying Al/Cu bilayers on a SiO2 on Si(100) substrate in the presence of a si milar to3 nm Al2O3 passivating layer. X-ray photoelectron spectroscopy (XPS ) measures a 1.0 eV shift of the Cu 2p(3/2) peak and a 1.6 eV shift of the valance band relative to metallic Cu upon Al2Cu formation. Scanning electro n microscopy and electron back-scattered diffraction show that the Al2Cu fi lm is composed of 30-70 mum wide and 10-15 mm long cellular grains with (11 0) orientation. The atomic composition of the film as estimated by energy d ispersive spectroscopy is 67 +/- 2% Al and 33 +/- 2% Cu. XPS scans of Al2O3 /Al2Cu taken before and after air exposure indicate that the upper Al2Cu la yers undergo further oxidation to Al2O3 even in the presence of similar to5 nm Al2O3. The majority of Cu produced from oxidation is believed to be exc luded from the Al2O3 layers, based upon the lack of evidence for metallic C u in the XPS scans. In contrast to Al/Cu passivated with Al2O3. melting/res olidifying the Al/Cu bilayer without Al2O3 results in phase-segregated dend ritic film growth. (C) 2001 The Electrochemical Society.