High-density Plasma Etching of RF-Sputtered Indium-Zinc-Oxide Films in Ar, Ar/Cl_2, and Ar/CH_4/H_2 Chemistries

摘要

In this work, we investigate the potential of chlorine and methane/hydrogen plasma chemistries for the dry etching of rf-sputtered Indium-Zinc-Oxide (IZO) layers. The influence of the discharge chemistry on the post-etched surface morphology and near-surface stoichiometry is also investigated. 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 a strong increase of the IZO etch rate. 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. While the etch-induced damage in Ar and Ar/Cl_2 plasmas are constrained to the surface vicinity, etching in CH_4/H_2/Ar produces a Zn-rich surface layer, whose thickness (～40 nm) is well-above the expected range of incident ions in the material (～1.5 nm). Auger electron spectroscopy measurements as a function of plasma exposure time indicate that diffusion of O, Zn and In atoms upon preferential desorption of volatile O-and In-containing reaction products is responsible for damage propagation.