Leakage current suppression in solution-deposited barium titanate films on copper foils

Processing of high-permittivity ceramic films on free-standing bare copper foil for subsequent organic package integration requires high-temperature crystallization at low oxygen pressures. This frequently can result in incorporation of oxygen vacancies and copper diffusion into the film that enhances leakage current and degrade the reliability characteristics. Leakage current, breakdown voltage and electrical reliability of the devices were improved by incorporating 1% excess barium and manganese dopant. Incorporation of dopants also resulted in enhanced densification and grain refinement. Leakage current analysis indicated Space-Charge-Limited Conduction as the dominant conduction mechanism in both undoped and doped films. The mechanisms by which acceptor dopants suppress oxygen vacancy creation and migration are discussed. Capacitance densities of 1.5-3 mu F/cm(2), with breakdown voltages above 10 V, were demonstrated for 250-500 nm thin barium titanate films.