Corrosion of amorphous alumina in deionized water under mild condition

Alumina is known for its inertness and chemical resistance. Unless the condition is near the critical point, it is conventional to assume that the reaction between alumina and water does not take place within short period of time. This assumption also includes amorphous alumina, which is formed via sputtering to protect microelectronic components. This work shows that amorphous alumina film indeed reacts with deionized (DI) water within minutes even in mild conditions. The reaction results in defects on the surface of the alumina, which ultimately progresses into the film, causing a dense film to become porous, as though it had become corroded. Severe surface defects are formed within 60 min of immersion in deionized water at 50 degrees C. Characterizations of the corroded film and the study of the effects of various parameters on defect formation indicate that the defects are associated with the hydrolysis of the amorphous alumina.