The influences of moisture and fluorine on the characteristics of fluorinated silicate glass for copper metallization

In this study, the impacts of moisture and unstable fluorine on the fundamental properties of fluorinated silicate glass (FSG) are discussed. Specific thermal treatment and water-soaking treatment are applied to the FSG dielectric layer. The influences of the moisture and fluorine outgassing from the FSG layers on the integrity of the Cu/TaN _x∼0.5/Ta/FSG/ 〈Si〉 multilayer structure are investigated using transmission electron microscopy, Rutherford backscattering spectroscopy, and secondary ion mass spectroscopy. The results indicate that the formation of voids at the interface between the metallization layer and FSG film is correlated with the moisture and unstable fluorine in the FSG dielectric layer. Nevertheless, both of them can be eliminated by baking the FSG dielectrics prior to the subsequent metallization. Meanwhile, the dielectric constant and leakage current characteristics of the FSG film can be improved by driving out the moisture and unstable fluorine of the dielectric layer after baking in N ₂ at ambient conditions.