The Effects of Fluorine Passivation Using SF 6 Plasma on the Corrosion of Al(Cu 1%) at Grain Boundaries

Corrosion effects following the etching of Al(Cu 1%) using a SiCl 4 /Cl 2 /He/CHF 3 gas plasma have been evaluated. The phenomenon has been studied using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Auger electron spectroscopy (AES). It was found with SEM that the surface of Al(Cu 1%) was mainly corroded at the grain boundary. Using AES point analysis, the cause of selective corrosion at the grain boundary of Al(Cu 1%) has been investigated. The fluorine (F) and chlorine (Cl) on the etched Al(Cu 1%) have been analyzed with AES. The results showed that the contents of F and Cl on the post-SF 6 treated Al(Cu 1%) were different at each of the analyzed positions such as the grain boundaries and crystalline regions. This seems to result from the imperfect crystalline structure of Al(Cu 1%) grain boundaries. The effects of subsequent in situ SF 6 . plasma treatment on the etched Al(Cu 1%) has been also examined using XPS. It was also confirmed that F has passivated the Cl compounds. The AES and XPS results imply that Cl incorporated at the grain boundaries of the polycrystalline Al(Cu 1%) film accelerated the corrosion and could not be easily removed by subsequent SF 6 plasma treatment.