Etch Properties of HfO2 Thin Films using CH4/Ar Inductively Coupled Plasma

Abstract

In this study, we carried out an investigation of the etching characteristics (etch rate, selectivity) of HfO2 thin films in the CH4/Ar inductively coupled plasma. It was found that variations of input power and negative dc-bias voltage are investigated by the monotonic changes of the HfO2 etch rate as it generally expected from the corresponding variations of plasma parameters. At the same time, a change in either gas pressure or in gas mixing ratio result in non-monotonic etch rate that reaches a maximum at 2 Pa and for CH4 (20 %)/Ar (80 %) gas mixture, respectively. The X-ray photoelectron spectroscopy analysis showed an efficient destruction of the oxide bonds by the ion bombardment as well as showed an accumulation of low volatile reaction products on the etched surface. Based on these data, the ion-assisted chemical reaction was proposed as the main etch mechanism for the CH4- containing plasmas.