TEM In-Situ Electrical Testing of a FIB-prepared BaTiO3 Ceramic Base Metal Electrode Capacitor

High reliability capacitors require a dielectric layer with both high electrical resistivity and high static dielectric constant. The most commonly used material platform for low cost, base metal electrode capacitors (BME) consists of nickel electrodes and barium titanate-based dielectric layers. Barium titanate (BaTiO3) is ferroelectric material with dielectric constant that depends on factors including grain size and density of ferroelectric domain walls. Failure in BME’s typically occurs by slow degradation in electrical resistance followed by a rapid thermal event leading to a short. The initial degradation depends on the structure and composition of the BaTiO3-based dielectric and in particular oxygen vacancies that result from sintering in reducing environments. Oxygen vacancies in the BaTiO3 act as n-type dopants and reduce resistivity [1]. Considerable efforts have been made to counteract the effect of oxygen vacancies and restore the high resistivity by the addition of trace elements that replace the Ti +4 ions and act as p-type dopants. However, these elements can affect ferroelectric ordering. Furthermore, the distribution of trace elements is typically concentrated near the grain boundaries resulting in grains with non-uniform characteristics. Thus to create reliable capacitors the relationship between the local crystal structure, ferroelectric domain structure, electrical resistivity, and chemical composition is important to understand.