High-density plasma etching of indium–zinc oxide films in Ar/Cl 2 and Ar/CH 4/H 2 chemistries

Abstract

The dry etching characteristics of transparent and conductive indium–zinc oxide (IZO) films have been investigated using an inductively coupled high-density plasma. While the Cl 2-based plasma mixture showed little enhancement over physical sputtering in a pure argon atmosphere, the CH 4/H 2/Ar chemistry produced an increase of the IZO etch rate. On the other hand, the surface morphology of IZO films after etching in Ar and Ar/Cl 2 discharges is smooth, whereas that after etching in CH 4/H 2/Ar presents particle-like features resulting from the preferential desorption of In- and O-containing products. Etching in CH 4/H 2/Ar also produces formation of a Zn-rich surface layer, whose thickness (∼40 nm) is well-above the expected range of incident ions in the material (∼1 nm). Such alteration of the IZO layer after etching in CH 4/H 2/Ar plasmas is expected to have a significant impact on the transparent electrode properties in optoelectronic device fabrication.