Dry Etching Characteristics of ZrO2 Thin Films Using High Density Cl2/Ar Plasma

Abstract

The etch rates of ZrO2 thin films and the etch selectivity of ZrO2 to SiO2 in a Cl2/Ar plasma were investigated. It was found that the ZrO2 etch rate showed non-monotonic behaviour with increasing Ar fraction in the Cl2 plasma, but etch rate showed a monotonic trend with increasing source power, bias power, and substrate temperature. The maximum ZrO2 etch rate of 92.6 nm/min was obtained for the Cl2 (75%) /Ar (25%) gas mixture. At the same time, the relative volume densities of the radicals were monitored with optical emission spectroscopy (OES). The Auger electron spectroscopy (AES) analysis showed the efficient destruction of the oxide bonds from Zr-O bonds by the ion bombardment, as well as an accumulation of low volatile reaction product of Zr-Clx on the etched surface. Based on the experimental data, ion-assisted chemical etching was proposed as the main etch mechanism for the ZrO2 in the Cl2/Ar plasma.