Surface Chemical Reaction on HfO2 Thin Film Etched by High Density Plasma

Abstract

In this work, we investigated the etching characteristics of HfO2 thin films and the selectivity of HfO2 to SiO2 in an O-2/CF4/Ar inductively coupled plasma (ICP) system. The maximum etch rates of HfO2 thin films was 70nm/min at a gas mixing ratio of O-2/CF4/Ar (3:4:16 sccm). At the same time, the etch rate were measured as a function of the etching parameters, such as the ICP RF power, DC-bias voltage, and process pressure. The X-ray photoelectron spectroscopy analysis showed the efficient destruction of the oxide bonds by the ion bombardment, as well as the 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 CF4-containing plasmas.