Comparison of chlorine- and fluorine-based inductively coupled plasmas for dry etching of InGaZnO4 films

A comparative study of etch characteristics of the InGaZnO4 (IGZO) films has been performed in chlorine- (Cl2 and BCl3) and fluorine-based (CF4 and SF6) inductively coupled plasmas (ICPs). Higher IGZO etch rates were achieved with chlorine-based discharges due to the higher volatility of metal chloride etch products. The IGZO etch rate was significantly affected by ICP source power and rf chuck power, and maximum etch rates of ~ 1200 Å/min and ~ 1350 Å/min were obtained in fluorine-based and Cl2/Ar discharges, respectively. The etched surface morphologies of IGZO in 10BCl3/5Ar mixtures were better than the unetched control sample. Maximum etch selectivities of 1.4:1 for IGZO over HfO2, 3.1:1 for IGZO over Al2O3, and 1.2:1 for IGZO over yttria-stabilized zirconia were obtained.