A mathematical description of the switching behavior of ferroelectric thin films for FRAM applications

This paper presents a mathematical model that describes the switching behavior (Q sw as a function of applied voltage) of ferroelectric thin films tested using 4-pulse sequence (PUND) approach. The model consists of a distribution of threshold voltage (to switch the ferroelectric domains) and a linear Q(SW) increase in the high voltage range. It is demonstrated that this model can precisely describe the Q(SW) vs. applied voltage of ferroelectric thin films or integrated ferroelectric array capacitors. The physical meaning of the four parameters in the model will be discussed. Using these parameters, some integration process related effects such as interface layer and fringing effect can be quantitatively estimated. Using this model, the switching performance of ferroelectric capacitors at different temperatures can be predicted.