Reactive pulsed laser deposition of iridium oxide thin films

Highly conductive iridium oxide, IrO2, thin films have been successfully de posited on Si (100) substrates by reactive pulsed laser ablation from a met al iridium target in an oxygen atmosphere. By investigating the effects of both the oxygen pressure and the substrate temperature on the properties (n amely structure, morphology, and electrical resistivity) of IrO2 films, opt imum parameters have been identified for the growth of high-quality IrO2 fi lms. At 200 mTorr of oxygen ambient pressure, IrO2 films deposited at subst rate temperatures in the 100-550 degrees C range are polycrystalline with a preferred (101) orientation and exhibit a uniform and densely packed granu lar morphology with an average feature size increasing (from about 90 to 17 0 nm with the substrate temperature. The room-temperature resistivities of these IrO2 films compare well with those of bulk single-crystal iridium dio xide. IrO2 films with a resistivity of 39 +/- 4 mu Omega cm are obtained at a substrate temperature as low as 400 degrees C. When the substrate temper ature is varied from 300 to 550 degrees C, the resistivity Variations of Ir O2 films are correlated to the observed changes in the film morphology. (C) 1998 Elsevier Science S.A. All rights reserved.