Lifetime estimation due to imprint failure in ferroelectric SrBi2Ta2O9 thin films

Two different failure modes for a ferroelectric memory cell caused by impri nt, the read failure due to the loss of polarization, and the write failure due to the shift of the hysteresis loop are investigated. The quasistatic hysteresis loop allows us to distinguish which failure mode is dominating i n a ferroelectric random access memory application and, hence, it can also be used as a powerful tool for lifetime estimation of ferroelectric thin fi lms limited by imprint failure under operating conditions. The experimental results show that the write failure is only decisive for very low voltage operation (V-p < 1.25 V), whereas for the Pt/SrBi2Ta2O9/Pt under investigat ion the read failure is the dominant failure mode for operating voltages ex ceeding 1.25 V. (C) 2000 American Institute of Physics. [S0003-6951(00)0250 3-1].