Phase control of iridium and iridium oxide thin films in atomic layer deposition

The atomic layer deposition of iridium (Ir) and iridium oxide (IrO2) films was investigated using an alternating supply of (ethylcyclopentadienyl)(1,5-cyclooctadiene) iridium and oxygen gas at temperatures between 230 and 290 degrees C. The phase transition between Ir and IrO2 occurred at the critical oxygen partial pressure during the oxygen injection pulse. The oxygen partial pressure was controlled by the O-2/(Ar+O-2) ratio or deposition pressures. The resistivity of the deposited Ir and IrO2 films was about 9 and 120 mu Omega cm, respectively. In addition, the critical oxygen partial pressure for the phase transition between Ir and IrO2 was increased with increasing the deposition temperature. Thus, the phase of the deposited film, either Ir or IrO2, was controlled by the oxygen partial pressure and the deposition temperature. However, the formation of a thin Ir layer was detected between the IrO2 and SiO2 substrate. To remove this interfacial layer, the oxygen partial pressure is increased to a severe condition. And the impurity contents were below the detection limit of Auger electron spectroscopy in both Ir and IrO2 films. (C) 2008 American Institute of Physics.