Growth of highly textured iridium thin films and their stability at high temperature in oxygen atmosphere

International audienceThe growth and thermal stability of textured iridium thin films used as bottomelectrode in electronic devices based on ferroelectric materials were investigated.The thin films were grown using the dc magnetron sputtering technique.The Ir layers directly deposited on SiO2/Si substrates present a mixed (111) and(200) orientations, while the films grown on Ti seed layers exhibit a strongpreferred (111) orientation favoured by good matching with the titanium lattice.The substrate temperature during the growth of iridium/titanium stack has asignificant effect on the surface morphology of the iridium layer and its thermalstability. The as-grown surface of 20-nm-thick Ir films is smooth, having a rootmean-square (rms) roughness of 0.7 nm. After thermal annealing the Ir filmshows an increased surface roughness due to the formation of agglomerations.The change in the surface morphology of the Ir layer is due to titanium diffusionand its oxidation. Thicker and better crystallised iridium thin films annealed inoxygen atmosphere at 700 C show a good thermal stability with only a slightmodification of the surface morphology. Within the limits of experimental error,there is no change in the electrical resistivity before and after thermal annealing.The rms roughness has not varied significantly and the XPS investigation showsno traces of titanium oxide on iridium surface. Ir/Ti stack deposited under theoptimum conditions could be successfully used as electrode in devices based onoxide thin films