Characterization of iridium oxide thin films deposited by pulsed-direct-current reactive sputtering

Thin films of iridium oxide were deposited on silicon and borosilicate glass substrates by pulsed-direct-current (pulsed-DC) reactive sputtering of iridium metal in an oxygen-containing atmosphere. Optimum deposition conditions were identified in terms of plasma pulsing conditions, oxygen partial pressures, and substrate temperature. The films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and Rutherford backscattering spectroscopy. According to the results, it was possible to obtain films that are near-stoichiometric, smooth and uniform in texture. The films deposited without substrate heating were amorphous, and those deposited at substrate temperatures above 300 °C were found to have a homogeneous polycrystalline structure. The results also showed that pulsed-DC sputtered iridium oxide films were smoother and had lower micro-inclusions density than DC-sputtered films obtained under otherwise similar deposition conditions. This improvement in the film quality is at the expense of a tolerable decrease in the deposition rate.