AN INVESTIGATION ON THE LEAKAGE CURRENT AND TIME-DEPENDENT DIELECTRIC-BREAKDOWN OF FERROELECTRIC LEAD-ZIRCONATE-TITANATE THIN-FILM CAPACITORS FOR MEMORY DEVICE APPLICATIONS

Lead-zirconate-titanate (PZT) is an interesting ferroelectric material for the application of DRAM and nonvolatile memory devices. In this w ork, metal-PZT-metal capacitors with Au and Pt as the top and the bott om electrodes are fabricated. The leakage current, time dependent diel ectric breakdown (TDDB) lifetime and the correlation between them are studied. The leakage current is found to depend on the applied electri c field in a power law relationship. The exponent in the power law rel ation is found to be 0.88 in the low field region (lower than 100 kV/c m) and 9.6 in the high field region (larger than 100 kV/cm). The TDDB of the PZT capacitors is measured. An extrapolation method is proposed to obtain the projected TDDB lifetime from the time to breakdown (t(B D))data. The power law exponential extracted from the TDDB measurement in this method is found to be in good agreement with that obtained fr om the leakage current measurement. (C) 1996 American Institute of Phy sics.