Published online by Cambridge University Press: 10 February 2011
Etching behaviors of various Al alloy thin films in H2O2-based acidic etchants are investigated in this study. The pH and H2O2 content in the etchant are varied in order to simulate the case where Al thin films are subject to chemical-mechanical polishing (CMP) using slurries of different compositions. Corrosion current and thickness of the native oxide on pure-Al, AI-1%Si, Al-0.5%Cu, AI-1%Si-0.5%Cu, and AI-1%Cu thin films are determined from Tafel and ESCA analyses respectively. Comparisons between etch rate and CMP polish rate data suggest that Al-CMP removal process depends strongly on the chemical reactions by the oxidizer (slurry). Mechanical abrasion by the abrasive particles plays only an auxiliary role during Al CMP. In addition, alloy composition (% Si and % Cu) influence both etching and polishing behaviors to a great extent. The underlying mechanisms for etching and polishing are discussed.