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

Abstract

The TiO2 etching characteristics and mechanism in HBr/Cl-2/Ar inductively coupled plasma (with a fixed bias power of 200 W) were investigated. It was found that the TiO2 etching rate in Cl-2/Ar plasma is about 8 times faster than that in HBr/Ar plasma. In both HBr-rich (60% HBr + 20% Cl-2 + 20% Ar) and Cl-2-rich (20% HBr + 60% Cl-2 + 20% Ar) plasmas, an increase in gas pressure (4-10 mTorr) results in a non-monotonic increase in TiO2 etching rate, while the variation of input power (500-800 W) causes a monotonic acceleration of the etching process. Plasma diagnostics by Langmuir probes and zero-dimensional plasma modeling provided data on plasma parameters, steady-state densities, and fluxes of active species on the etched surface. The model-based analysis of the TiO2 etching kinetics shows a transitional regime of ion-assisted chemical reaction with domination of a chemical etching pathway. (C) 2012 The Japan Society of Applied Physics