Humidity and polarity influence on MIM PZT capacitor degradation and breakdown

This paper presents a reliability study on unpackaged metal-PZT-metal capacitors. Both ramped voltage stress (RVS) and time dependent dielectric breakdown (TDDB) measurements show that environmental humidity dramatically worsens the PZT reliability. Visible breakdown spots on the surface of PZT capacitors are studied in detail. The measurement results indicate that both reversible and irreversible PZT degradation/breakdown happen during TDDB. The dependence of time to breakdown on polarity of applied voltage is argued to relate to the crystal structure of PZT and the stack of the PZT capacitor.