High dielectric constant TiO2 thin films on a Ru electrode grown at 250 °C by atomic-layer deposition

${\mathrm{TiO}}_2$ thin films with high dielectric constants (83–100) were grown on a Ru electrode at a growth temperature of 250 °C using the atomic-layer deposition method. The as-deposited films were crystallized with rutile structure. Adoption of ${\mathrm{O}}_3$ with a very high concentration $(400\mathrm{g}∕{\mathrm{m}}^3)$ was crucial for obtaining the rutile phase and the high dielectric constant. The leakage current density of a ${\mathrm{TiO}}_2$ film with an equivalent oxide thickness of 1.0–1.5 nm was ${10}^{-6}–{10}^{-8}\mathrm{A}∕{\mathrm{cm}}^2$ at $\pm 1\mathrm{V}$ . All these electrical properties were obtained after limited postannealing where the annealing temperature was $<500°\mathrm{C}$ , which is crucial to the structural stability of the Ru electrode. Therefore, these ${\mathrm{TiO}}_2$ films are very promising as the capacitor dielectrics of dynamic random access memories. ${\mathrm{TiO}}_2$ films grown on a bare Si wafer or Pt electrode by the same process had anatase structure and a dielectric constant of $\sim 40$ .