Impact of O3 feeding time on TiO2 films grown by atomic layer deposition for memory capacitor applications

Abstract

The effect of the O3 feeding time on the physical and electrical properties of TiO2 thin films on Ru electrodes was investigated. The density, composition, chemical state, and crystalline structure of the TiO2 films were almost identical, irrespective of the O3 feeding time, even when the TiO2 films were grown under subsaturated conditions with respect to the O3 feeding. However, increasing the O3 feeding time to more than 3s brought about surface roughening and severe local protrusion of the films, which significantly increased their leakage current density. The conduction band offset of the film surface was generally small and was not increased by increasing the O3 feeding time nor was the leakage current improved. Consequently, a minimum tox of 0.8nm with a leakage current density <∼1×10−7A∕cm2 at an applied voltage of 0.8V was achieved at an O3 feeding time of 2–3s.