Dry etching of zinc-oxide and indium-zinc-oxide in IBr and BI3 plasma chemistries

The dry etching characteristics of bulk single-crystal zinc-oxide (ZnO) and RF-sputtered indium-zinc-oxide (IZO) films have been investigated using an inductively coupled high-density plasma in Ar/IBr and Ar/BI3. In both plasma chemistries, the etch rate of ZnO is very similar to that of IZO, which indicates that zinc and indium atoms are driven by a similar plasma etching dynamics. IBr and BI3-based plasmas show no enhancement of the etch rate over pure physical sputtering under the same experimental conditions. The etched surface morphologies are smooth, independent of the discharge chemistry. From Auger electron spectroscopy, it is found that the near-surface stoichiometry is unchanged within experimental error, indicating a low degree of plasma-induced damage.