Etching Behavior and Mechanism of In- and Ga-Doped ZnO Thin Films in Inductively Coupled BCl3/Cl2/Ar Plasmas

Abstract

The etching characteristics and mechanism of In- and Ga-doped ZnO (IGZO) thin films in BCl3/Cl2/Ar inductively coupled plasma at a fixed gas pressure (6 mTorr) were investigated. It was found that the substitution of Cl2 for BCl3 in the BCl3/Cl2/Ar gas mixture results in the maximum IGZO etching rate in 40% BCl3 + 40% Cl2 + 20% Ar. In both Cl2-rich (20% BCl3 + 60% Cl2 + 20% Ar) and BCl3-rich (60% BCl3 + 20% Cl2 + 20% Ar) plasmas, increases in input power (500–800 W) and bias power (100–250 W) cause the monotonic acceleration of the IGZO etching process. Plasma diagnostics using Langmuir probes and zero-dimensional plasma modeling provided the data on plasma parameters and fluxes of active species. It was concluded that the IGZO etching process is not limited by the ion–surface interaction kinetics as well as involves BClx radicals.