Etching Characteristics and Mechanisms of TiO2 Thin Films in HBr/Ar and Cl-2/Ar Inductively-Coupled Plasmas

Abstract

The TiO2 etching characteristics and mechanisms in HBr/Ar and Cl-2/Ar inductively-coupled plasmas were investigated under fixed gas-mixing ratio and bias power conditions. It was found that in both systems, an increase in gas pressure from 4 to 10 mTorr results in a non-monotonic TiO2 etching rate, while a variation of input power in the range 500-800 W causes a faster-than-linear acceleration of the etching process. Plasma diagnostics performed by Langmuir probes and zero-dimensional plasma modeling provided data on plasma parameters, steady-state densities, and fluxes of the active species on the etched surface. The model-based analysis of the etching mechanism showed that for the given set of processing parameters, the TiO2 etch kinetics correspond to the transitional regime of ion-assisted chemical reaction in which a chemical-etch pathway dominates.