To eliminate corrosion, a subsequent treatment of SF6 plasma after an Al-Cu etching has been carried out. X-ray photoelectron spectroscopy (XPS) studies showed that the F content on the Al-Cu alloy surface caused by the SF6 treatment increased as the chamber pressure increased, and Cl incorporated during the Al-Cu alloy etching was not totally removed by the post treatment using SF6 gas plasma. However, it was confirmed by scanning electron microscopy (SEM) that corrosion could be eliminated by the SF6 treatment at 300 mTorr. At the same time, the results of angle-resolved XPS showed that elemental Al was distributed under the layer of F-related compounds. These results indicate that SF6 treatment can reduce the corrosion of Al-Cu alloy films by producing a F-containing layer on the etched surface. From the SEM image, the existence of a passivation layer on the Al-Cu alloy film surface by fluorine-related compounds was confirmed. The passivation layer prevents moisture penetration on the SF6-treated surface and suppresses corrosion successfully. The composition of the passivation layer measured by angle-resolved XPS was mostly uniform within a few hundred nm thickness. The passivation film was composed of 32% Al, 43% F, 2% Cl, and 10% O at a SF6 pressure of 300 mTorr, Approximately 2% of Cl was uniformly distributed in the film.