Enhanced etching of tin-doped indium oxide due to surface modification by hydrogen ion injection

It is known that the etching yield (i.e., sputtering yield) of tin-doped indium oxide (ITO) by hydrocarbon ions (CH x + ) is higher than its corresponding physical sputtering yield [H. Li et al., J. Vac. Sci. Technol. A 33 , 060606 (2015)]. In this study, the effects of hydrogen in the incident hydrocarbon ion beam on the etching yield of ITO have been examined experimentally and theoretically with the use of a mass-selected ion beam system and by first-principles quantum mechanical (QM) simulation. As in the case of ZnO [H. Li et al., J. Vac. Sci. Technol. A 35 , 05C303 (2017)], mass-selected ion beam experiments have shown that the physical sputtering yield of ITO by chemically inert Ne ions increases after a pretreatment of the ITO film by energetic hydrogen ion injection. First-principles QM simulation of the interaction of In 2 O 3 with hydrogen atoms shows that hydrogen atoms embedded in In 2 O 3 readily form hydroxyl (OH) groups and weaken or break In–O bonds around the hydrogen atoms, making the In 2 O 3 film less resistant to physical sputtering. This is consistent with experimental observation of the enhanced etching yields of ITO by CH x + ions, considering the fact that hydrogen atoms of the incident CH x + ions are embedded into ITO during the etching process.