Etch characteristics of gallium indium zinc oxide thin films in a HBr/Ar plasma

Gallium indium zinc oxide (GIZO) thin films patterned with a photoresist (PR) were dry etched using inductively coupled plasma (ICP) of HBr/Ar gas. The etch rate of the GIZO films and the etch selectivity of GIZO/PR decreased gradually as HBr gas was added to Ar. In addition, the etch rate increased with increasing ICP power and dc-bias voltage to the substrate. However, the etch rate was decreased with increasing gas pressure. X-ray photoelectron spectroscopy and atomic force microscopy revealed Br compounds on the film surface during the etching process. It can be concluded that the high density plasma etching of GIZO films using HBr/Ar gas follows a sputtering etching mechanism with the assistance of a chemical reaction on the films.