Multifrequency Retention Model of HfO2-Based FRAM

Ferroelectric random access memory (FRAM) based on hafnium oxide is one of the most promising alternatives to modern nonvolatile flash memory. Despite a number of excellent performances, the commercialization of this memory is hindered by its limited retention time, which still does not meet the 10-year electronics-industry standard. A specific feature of the retention performance is that it cannot be measured directly, because 10 years is required to measure the actual polarization loss. In this work, we present a method for predicting polarization loss over information storage time that takes into account two physical phenomena affecting the information storage and readout: the emergence and temporal evolution of the internal built-in electric field in poled ferroelectrics (the imprint effect) and kinetics of polarization switching that determines the dependence of the switching speed on switching voltage. The method allows to calculate the retention loss for a wide range of operating voltages and frequencies.