A reliability study on high-breakdown integrated ferroelectric capacitors.

Capacitors, with a capacitance density of up to 100 nF/mm(2) and a dielectric constant of 950-1600 were produced by optimizing the ferroelectric material combined with stacking. Accelerated lifetime (ALT) tests under elevated temperatures of 210-290 degrees C and dc fields of 25-250 kV/cm were performed and the lifetime criterion, common for ceramic multilayer capacitors, was employed: The increase of the current density by one order of magnitude is defined as the end of lifetime. The capacitor under these conditions is still functioning and therefore this criterion is more conservative than time dependent dielectric breakdown (TDDB). The activation energy and voltage dependence are determined from the ALT, to extrapolate to operation conditions. Activation energies of 1.1-1.6 eV have been determined and a dependence on the applied dc voltage was observed. All capacitors showed a lifetime of more than 10 years at 85 degrees C and 5 V.