Impact of Deep Ultraviolet-Ozone Photoactivation on Dielectric Properties of Amorphous SrTiO₃ Thin Films

Abstract

Strontium titanate SrTiO3 thin films have been fabricated by radio frequency magnetron sputtering on P-type Si at substrate temperature of 200°C. Two different postdeposition annealing methods were applied on the sputtered films. Specifically, conventional thermal annealing at 300°C for 60 min and photoactivation treatment under deep ultraviolet-ozone for 30 min. The dielectric properties of the SrTiO3 thin films were investigated by fabricating Au/STO/p-Si MOS capacitors. A dielectric constant (κ) with a value of 13 was obtained for as-deposited film, which has a thickness of 107 nm. While post-annealed samples showed elevated values of κ, precisely, 15.33 and 19.32 for films exposed to deep ultraviolet-ozone photoactivation and films annealed at 300°C, respectively. All devices showed a leakage current in the order of 10-8 A/cm2 at 1V. Based on XPS analysis, photo-activated films revealed the lowest percentage of oxygen vacancies, which designates the capability of this technique to enhancing films quality at a lower temperature.