Highly accelerated lifetime testing (HALT) of lead zirconate titanate (PZT) thin films

The lifetime of PZT films under dc field is relevant for both capacitive and electromechanical applications. To assess the factors controlling the lifetime, a series of highly accelerated lifetime tests (HALT) were performed on /spl sim/0.88 /spl mu/m thick sol-gel PZT (52/48) thin films exposed to temperatures ranging from 100 /spl deg/C to 180 /spl deg/C and electric fields ranging from 284 to 455 kV/cm. Using a lognormal plot of failure times to represent the data, an S-shaped pattern, indicative of two failure modes, is observed. The later failures represent the limiting device lifetimes and these values that were used to compute lifetime prediction values. It was found that the activation energy for failure was /spl sim/1.1 eV and the voltage acceleration factor was /spl sim/5.3. Scanning electron microscopy analysis revealed that arc discharge is the most prominent failure mechanism during operation.