Effect of gas mixing ratio on etch behavior of ZrO2 thin films in Cl2-based inductively coupled plasmas

Abstract

The analysis of the ZrO2 thin film etch mechanism in the Cl2∕Ar, Cl2∕He, and Cl2∕N2 inductively coupled plasmas was carried out. It was found that an increase in additive gas fraction at fixed gas pressure and input power results in increasing ZrO2 etch rate, which changes from 1.2nm∕min for pure Cl2 plasma up to 3.15, 2.40, and 2.31nm∕min for 80% Ar, N2, and He, respectively. Langmuir probe diagnostics and zero-dimensional plasma modeling indicated that both plasma parameters and active species kinetics are noticeably influenced by the initial composition of the gas mixture. From the model-based analysis of etch kinetics, it was shown that, similarly to the case of BCl3-based plasmas, the behavior of the ZrO2 etch rate corresponds to the ion-flux-limited etch regime.