Optimization of electric properties of high-k zirconium dioxide by varying deposition and annealing conditions

ZrO2 thin films with a smooth surface were synthesized on silicon by atomic vapor deposition™ using Zr[OC(CH3)3]4 as precursor. The maximum growth rate (∼7 nm min−1) and strongest crystalline phase were obtained at 400 °C. The increase of the deposition temperature reduced the deposition rate to 0.5 nm min−1 and changed the crystalline ZrO2 phase from cubic/tetragonal to monoclinic. These films showed no enhancement of the dominating monoclinic phase by annealing. The values of the dielectric constant (up to 32) and leakage current density (down to 1.2×10−6 A cm−2 at 1×106 V cm−1) varied depending on the deposition temperature and film thickness. The midgap density of interface states was Nit=5×1011 eV−1 cm−2. The leakage current and the density of interface states were lowered by the annealing to 10−7 A cm−2 at 1×106 V cm−1 and to 1010 eV−1 cm−2, respectively. However, this also led to a decrease of the dielectric constant.