Etching Behavior and Mechanism of In- and Ga-Doped ZnO Thin Films in Inductively Coupled BCl3/Cl-2/Ar Plasmas

Abstract

The etching characteristics and mechanism of In- and Ga-doped ZnO (IGZO) thin films in BCl3/Cl-2/Ar inductively coupled plasma at a fixed gas pressure (6 mTorr) were investigated. It was found that the substitution of Cl-2 for BCl3 in the BCl3/Cl-2/Ar gas mixture results in the maximum IGZO etching rate in 40% BCl3 + 40% Cl-2 + 20% Ar. In both Cl-2-rich (20% BCl3 + 60% Cl-2 + 20% Ar) and BCl3-rich (60% BCl3 + 20% Cl-2 + 20% Ar) plasmas, increases in input power (500-800W) and bias power (100-250W) 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. (C) 2012 The Japan Society of Applied Physics