Patent attributes
An Al2O3 film with a thickness greater than that of a wiring is formed as a protective film, and then the Al2O3 film is polished by CMP until a conductive barrier film is exposed. Namely, CMP is applied to the Al2O3 film by utilizing the conductive barrier film as a stopper film. Next, a silicon oxide film is formed over the entire surface by, for example, a high-density plasma method, and then the surface thereof is flattened. Subsequently, another Al2O3 film is formed on the silicon oxide film as a protective film for preventing intrusion of hydrogen or moisture. Further, another silicon oxide film is formed on the Al2O3 film, for example, by a high-density plasma method. Then, a via hole reaching the conductive barrier film is formed through the silicon oxide film, the Al2O3 film and the silicon oxide film, and then a W plug is embedded therein.
