Scaling reliability and modeling of ferroelectric capacitors

We report on reliability properties of MOCVD PZT ferroelectric capacitors as a function of film thickness. Data is presented for fatigue, thermal depolarization, and imprint. It is important to be able to model these parameters as they can significantly affect the switching polarization, which in turn affects the signal margin of an FRAM circuit. A ferroelectric SPICE model is presented that can be used to accurately simulate hysteresis and switching polarization behavior. This model agrees with experimental data and can be used to simulate FRAM circuit behavior through "end of life".