Rutile-type TiO 2 thin film for high- k gate insulator

Abstract

We investigated rutile-type titanium dioxide (TiO 2) films for possible use as a high- k gate insulator. The TiO 2 thin films were directly deposited on Si substrates using a RF magnetron sputtering method with a sintered oxide target. A single phase of rutile-type TiO 2 whose dielectric constant of approximately 75 was obtained when the film was deposited in an inert gas atmosphere and annealed at 800 °C in an oxidizing gas atmosphere. The oxygen ions were deficient in the as-deposited film, and consequently, a sufficient oxygen supply was needed to crystallize the film to a single phase of rutile during the post-annealing. However, the interfacial SiO 2 layer between the TiO 2 and the Si substrate simultaneously grew thicker than 2 nm. As the interfacial SiO 2 grew, the leakage current was decreased and the equivalent oxide thickness was increased, in the Au/rutile-type TiO 2/Si capacitor. Therefore, we concluded that the growth of the interfacial SiO 2 layer thicker than 2 nm is inevitable to form the single phase of rutile-type TiO 2 and to decrease the leakage.