A study on the etch characteristics of ITO thin film using inductively coupled plasmas

In this study, the high-density plasma etching of indium tin oxide (ITO) films used for transparent electrodes in display devices have been investigated. The etch characteristics of ITO as a function of Ar/CH4 gas mixtures were analyzed using quadrupole mass spectrometry (QMS), optical emission spectroscopy (OES), and electrostatic probe (ESP). ITO etch rates were increased with the addition of moderate amount of CH4 to Ar due to the increased chemical reaction between CH3 or H and ITO in addition to the physical sputtering of ITO by Ar ion bombardment. However, the addition of excess amounts of CH4 decreased the ITO etch rates, possibly due to the increased polymer formation on the ITO surface. Also, the data obtained by QMS and OES suggested that CH3 radicals are more actively involved in the etching of ITO compared to H radicals.