AES, work function and gravimetric measurements of the oxygen interaction with Al and Cu film surfaces

Abstract

The interaction of oxygen with Al and Cu films was investigated by means of gravimetric uptake, Auger electron spectroscopy (AES) and work function changes. For Al it was possible to separate two reaction rates, a logarithmic one for an oxygen uptake < 6×10 −8 g/cm 2 with only a slight decrease of the reaction rate and an inverse logarithmic one for mass uptake > 8×10 −8 g/cm 2 . The interaction of Cu films with oxygen is characterized by a drastic decrease of the sticking coefficient from the very beginning of exposure. The maximum mass gain attainable at 7×10 5 L with 4×10 −8 g/cm 2 is evidently below a dissociative one monolayer coverage. From the AES, ELS and work function measurements we could prove the growing of aluminum oxide from the very beginning of oxygen interaction. Contrary, on evaporated Cu films no significant changes in the Auger line shape and the energy loss spectra were detected up to an exposure of 7×10 5 L. This stage of oxygen interaction with Cu is described as chemisorption.