Wake-Up and Imprint Effects in Hafnium Oxide-Based Ferroelectric Capacitors during Cycling with Different Interval Times

This work experimentally investigated the wake-up behaviors of hafnium oxide-based ferroelectric capacitors by manipulating the interval time between each characterization cycle. Both Positive-Up-Negative-Down (PUND) and Negative-Down-Positive-Up (NDPU) waveforms were used as the stress and measurement waveforms in the experiments. It was found that the imprint occurs as the total interval time increases to a several-seconds level. However, this only affects the remnant polarization (PR) of ferroelectric capacitors when stressed by NDPU waveforms, since the voltage amplitude saturates under the PUND stress conditions and does not influence the PR. The wake-up behavior has been proved to be caused by the defects redistribution during electrical cycling. Notably, when using PUND waveforms, the change in the interval time can result in different increase rates of PR, indicating the possibility of recovery during the intervals. This recovery leads to a slower wake-up when cycling with a longer interval time. Moreover, it is observed that this PR recovery could reach saturation after several seconds of the interval time. This comprehensive investigation of wake-up and imprint behaviors can provide new insights to evaluate and enhance the reliability of ferroelectric memories.