Preparation and properties of ZrO₂ and TiO₂ films and their nanolaminates by atomic layer deposition

Nanolayers of ZrO₂ and TiO₂ and their nanolaminates were grown on silicon wafer by an atomic layer deposition process. Precursors of tetrakis (dimethylamido) zirconium and tetrakis (dimethylamido) titanium were used to deposit ZrO₂ and TiO₂ films at different temperatures, respectively. The XRD results show that ZrO₂ films began to crystallize at the deposition temperature of 300 °C, and the cubic phase was first formed when the thickness of the film reached 16.5 nm, and then monoclinic phase appeared in the film when the thickness further increased. The as-deposited TiO₂ films exhibited anatase phase at the deposition temperature range of 50-300 °C. AFM morphologies indicate that both ZrO₂ and TiO₂ films were uniform and smooth. Nanolaminates of ZrO₂ and TiO₂ were obtained by deposition of ZrO₂ and TiO₂ layers at 300 °C alternatively with precise layer thickness control. The results show that the nanolaminates exhibited a giant dielectric constant of 850 at low frequency which was much higher than the individual dielectric constants of ZrO₂ and TiO₂. The nanolaminates of ZrO₂ and TiO₂ with the giant dielectric constant have potential applications for high-k dielectric materials.