Etch characteristics of indium zinc oxide thin films using inductively coupled plasma of a Cl2/Ar gas

Inductively coupled plasma reactive ion etching of indium zinc oxide (IZO) thin films masked with a photoresist was performed using a Cl2/Ar gas. The etch rate of the IZO thin films increased as Cl2 gas was added to Ar gas, reaching a maximum at 60% Cl2 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 Cl2 concentrations was smoother than that of the films etched at low Cl2 concentrations. These results suggest that the dry etching of IZO thin films in a Cl2/Ar gas occurs according to a reactive ion etching mechanism involving ion sputtering and a surface reaction.