Dielectric reliability in amorphous film bubble devices

Using fast response detecting and recording equipment the breakdown voltage spectra of thin film dielectrics (with a GdCoMo first electrode and permalloy counter-electrode) were measured as a function of time and temperature during application of linearly increasing (ramp) voltages. For 1000 Å thick SiO2films the dielectric breakdown events occurring at high voltages were seen to be strictly voltage-dependent, whereas those breakdowns occurring at low voltages exhibited a definite time-dependence in addition to a voltage-dependence. In this low voltage region slowly increasing voltages (low ramp rates) resulted in significantly greater numbers of cumulative failures, for a given attained voltage, than did rapidly increasing voltages. This time-dependence, transformed through a simple kinetic power law to a constant applied voltage experiment was found to be consistent with Peek´s law of dielectric breakdown. The data and analysis suggest that reliable device operation will not be achieved if electric fields in excess of 0.6 × 10⁶V/cm are applied across the dielectric.