Effects of Post-Annealing Temperatures and Ambient Atmospheres on the Electrical Properties of Ultrathin (Ba,Sr)TiO₃ Capacitors

Abstract

Ultrathin (Ba,Sr)TiO3 (BST) film capacitors with a Pt/Ba0.5Sr0.5TiO3(30 nm)/Pt/TiN/Si structure were fabricated. To investigate the effects of annealing temperatures, capacitors were annealed in flowing Ar or O2 at temperatures ranging from 400°C to 600°C for 30 min. The electrical properties of the annealed samples were strongly dependent on the annealing temperatures. In the capacitors annealed at 500°C (in Ar and O2) and 550°C (in O2), the leakage current decreased to a level of 10-8 A/cm2 when the bias voltage was ±1.5 V. In the as-deposited sample, the maximum capacitance appeared at a bias voltage of -1 V. However, the maximum capacitance increased and appeared at the zero bias voltage after annealing. These phenomena are believed to be defect-related (due to oxygen vacancies). The annealing atmospheres were also found to have an effect on preserving the morphology of the Pt electrodes.

Contributions to the dielectric losses of textured SrTiO3 thin films with Pt electrodes

“…In the literature, it has been shown that leakage characteristics and Schottky barrier heights in Pt/perovskite structures are sensitive to annealing and deposition conditions [27,[29][30][31][32]. In particular, it has been established that oxygen anneals reduced high field leakage, whereas forming gas (hydrogen) anneals increased high-field leakage in SrTiO 3 and BST films with Pt electrodes.…”