Influence of Bottom Electrodes and Interface Layers on (Ba,Sr)TiO3 Thin Film Leakage Current

Abstract

The effect of bottom electrodes of (Ba,Sr)TiO3 (BST) thin film capacitors on leakage current characteristics was investigated. Iridium (Ir), titanium (Ti) and tantalum (Ta) bottom electrodes and SiN interface layer were deposited prior to BST deposition. On the basis of time-dependent and temperature-dependent leakage current characteristics, the leakage mechanism was investigated. It is found that the leakage current in BST with the Ta bottom electrode (Ir/BST/Ta/Si) is dominated by dielectric relaxation current due to the existence of thick TaOx. Leakage currents in BST with the Ir bottom electrode (Ir/BST/IrOx/Ir/Si) and BST on Si substrate (Ir/BST/SiO2/Si) were determined by dielectric relaxation characteristics at low electric field and by Poole–Frenkel emission at high electric field. The leakage current in BST with the Ti bottom electrode (Ir/BST/Ti/Si) was dominated by Poole–Frenkel emission at the range of applied field.