The Phase Control of Iridium and Iridium Oxide in Atomic Layer Deposition: A Report

Kim Sung-Wook

The atomic layer deposition (ALD) of iridium (Ir) and iridium oxide (IrO2) films was investigated using an alternating supply of (ethylcyclopentadienyl)(1,5-cyclooctadiene) iridium [Ir(EtCp)(COD)] and oxygen gas at temperatures between 230 and 290 °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 O2/(Ar+O2) ratio or deposition pressures. The resistivity of the deposited Ir and IrO2 films was about 9 and 120 μΩ-cm, respectively. In addition, the critical oxygen partial pressure for the phase transition between Ir and IrO2 was increased with increasing a deposition temperature. Thus, the phase of the deposited film, either Ir or IrO2, was controlled by the oxygen partial pressure, and a deposition temperature. However, a formation of thin Ir layer was detected between IrO2 and SiO2 substrate at IrO2 formation condition. To remove this interfacial layer, oxygen partial pressure was increased to severe condition.