Atomic Layer Deposition and Electrical Properties of SrTiO3 Thin Films Grown Using Sr(C11H19O2)2, Ti(Oi-C3H7)4, and H2O.

Atomic layer deposited SrTiO₃ (STO) thin films were grown using Sr(C₁₁H₁₉O₂)₂ and Ti(Oi-C₃H₇)₄ with a remote plasma activated or thermal H₂O vapor as oxidant at growth temperatures ranging from 190 to 270°C. The as-grown films were amorphous and showed a low effective dielectric constant of ∼20 with a low leakage current density (<10^-7 A/cm² at 1 V). The chemical binding status of the Sr ions varied with the degree of crystallization of the STO film. A reasonable film growth rate and stoichiometric cation composition were obtained when the vaporization temperature of Sr-precursor was <200°C with the thermal H₂O vapor. The low density of the as-grown film induced a large shrinkage in the film thickness which caused microcracking of the crystallized films during postannealing, even with the increased H₂O supply. Adoption of thin (∼5 nm) crystallized seed layer before the main layer STO growth improved the microstructure after the crystallization and the leakage current performance. As a result of the process optimization, the best electrical properties of an STO film grown on a Ru electrode were 0.45 nm for the equivalent oxide thickness and 1 X 10^-3A/cm² for the leakage current density at 1 V. [ABSTRACT FROM AUTHOR]