Inductively coupled plasma reactive ion etching of indium zinc oxide (IZO) thin films masked with a photoresist was performed using a Cl-2/Ar gas. The etch rate of the IZO thin films increased as Cl-2 gas was added to Ar gas, reaching a maximum at 60% Cl-2 and decreasing thereafter. The degree of anisotropy in the etch profile improved with increasing coil rf power and dc-bias voltage. Changes in pressure had little effect on the etch profile. X-ray photoelectron spectroscopy confirmed the formation of InCl3 and ZnCl2 on the etched surface. The surface morphology of the films etched at high Cl-2 concentrations was smoother than that of the films etched at low Cl-2 concentrations. These results suggest that the dry etching of IZO thin films in a Cl-2/Ar gas occurs according to a reactive ion etching mechanism involving ion sputtering and a surface reaction. (C) 2009 Elsevier B.V. All rights reserved.