A process was investigated to remove HfO2 gate dielectric film that had been deposited and annealed under various conditions. The etch rate of HfO2 annealed at 950 degreesC was 0.14 Angstrom/min in 10% HF, but increased up to 90 Angstrom/min after Ar ion bombardment. The crystalline structure of the annealed HfO2 films collapsed upon bombardment by Ar ions. The amorphization and rarefaction of HfO2 by Ar ion bombardment were responsible for the dramatic increase of the etch rates. Almost no consumption of the underlying Si substrate was observed after the removal of the HfO2 dielectric films. (C) 2004 The Electrochemical Society.