Comparison of chlorine- and fluorine-based inductively coupled plasmas for dry etching of InGaZnO_4 films

摘要

A comparative study of etch characteristics of the InGaZnO_4 (IGZO) films has been performed in chlorine- (Cl_2 and BCl_3) and fluorine-based (CF_4 and SF_6) 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 A/min and ～1350 A/min were obtained in fluorine-based and Cl_2/Ar discharges, respectively. The etched surface morphologies of IGZO in 10BCl_3/5Ar mixtures were better than the unetched control sample. Maximum etch selectivities of 1.4:1 for IGZO over HfO_2, 3.1:1 for IGZO over Al_2O_3, and 1.2:1 for IGZO over yttria-stabilized zirconia were obtained.