PASSIVATION ROLE OF FLUORINE ON THE ANTICORROSION OF ALCU FILMS AFTERPLASMA-ETCHING

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 caus ed by the SF6 treatment increased as the chamber pressure increased, a nd Cl incorporated during the Al-Cu alloy etching was not totally remo ved by the post treatment using SF6 gas plasma. However, it was confir med by scanning electron microscopy (SEM) that corrosion could be elim inated by the SF6 treatment at 300 mTorr. At the same time, the result s of angle-resolved XPS showed that elemental Al was distributed under the layer of F-related compounds. These results indicate that SF6 tre atment can reduce the corrosion of Al-Cu alloy films by producing a F- containing layer on the etched surface. From the SEM image, the existe nce of a passivation layer on the Al-Cu alloy film surface by fluorine -related compounds was confirmed. The passivation layer prevents moist ure penetration on the SF6-treated surface and suppresses corrosion su ccessfully. The composition of the passivation layer measured by angle -resolved XPS was mostly uniform within a few hundred nm thickness. Th e 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 dist ributed in the film. (C) 1998 American Vacuum Society.