In-situ analysis of positive and negative energetic ions generated during Sn-doped In2O3 deposition by reactive sputtering

Abstract Using a quadrupole mass spectrometer combined with an energy analyser, we have investigated the in-situ energy distribution of highly energetic ions generated during reactive sputtering of In–Sn alloy (IT) targets and non-reactive sputtering of Sn-doped In 2 O 3 (ITO) ceramic targets. Ar + , In + , O + , O − , O 2 − , InO − and InO 2 − ions with kinetic energies greater than 40 eV were clearly observed. Upon increasing the O 2 flow ratio for reactive sputtering, the surface of the IT target changes from metal (metal mode) to oxide (oxide mode) via a state of mixed metal and oxide (transition region). O − ions with the kinetic energy corresponding to cathode voltage are generated at the oxide layer, which expands upon the target surface with increasing O 2 flow ratio in the metal mode and the transition region. In contrast, the flux of 60-eV Ar + ions decreases with increasing O 2 flow ratio. The presence of 125- and 200-eV In + ions is attributed to the dissociation of InSnO 2 − and InO 2 − with the kinetic energy corresponding to cathode voltage, respectively, while the presence of 40- and 150-eV O + ions is attributed to the dissociation of InO 2 − and O 2 − with the kinetic energy corresponding to cathode voltage, respectively.