Etch characteristics of HfO2 thin films by using CF4/Ar inductively coupled plasma

In this study, we carried out an investigation of the etching characteristics (etch rate, selectivity) of HfO2 thin films in the CF4/Ar inductively coupled plasma (ICP). The maximum etch rate of 54.48 nm/min for HfO2 thin films was obtained at CF4/Ar (=20:80%) gas mixing ratio. At the same time, the etch rate was measured as function of the etching parameters such as ICP RF power, DC-bias voltage, and process pressure. The X-ray photoelectron spectroscopy analysis showed an efficient destruction of the oxide bonds by the ion bombardment as well as an accumulation of low volatile reaction products on the etched surface. Based on these data, the chemical reaction was proposed as the main etch mechanism for the CF4-containing plasmas.

► We carried out the etching characteristics of HfO2 thin films in the CF4/Ar plasma.
► Experiments were performed with variations of CF4 gas mixing ratio.
► The oxide bonds on surface were efficient destruct by the ion bombardment.
► Hf interacted with the F radicals by adding CF4, but it remained at the surface.