Atomic layer deposition of high-permittivity TiO2 dielectrics with low leakage current on RuO2 in TiCl4-based processes

Capacitor structures with undoped and Al-doped TiO2 dielectrics grown on RuO2 electrodes by TiCl4-based atomic layer deposition were investigated. In the undoped films, relative permittivity values up to 160 were obtained. The leakage current densities were as low as 3 × 10−8 and 3 × 10−7 A cm−2 in the TiO2 films with capacitance equivalent thicknesses (CETs) of 0.49 and 0.39 nm, respectively, at a voltage of 0.8 V. Al doping of TiO2 led to a decrease of leakage current as well as permittivity. As a consequence, comparable leakage current densities were obtained for undoped and Al-doped films at similar CET values. (paper)