Electric-field dependence of cycle endurance in HfO2-based ferroelectric capacitors

Abstract

The cycle endurance characteristics of HfO2-based ferroelectric (FE-HfO2) capacitors were systematically investigated in terms of area, temperature, film thickness, and ferroelectric polarization. Cycle endurance exhibited distinct electric-field dependent behavior, which is classified into low, middle, and high field regimes. For area, the electric-field dependence does not change with area. The endurance cycle followed the Weibull distribution, and the Weibull slope is small at low field. For temperature, the electric-field dependence does not change with temperature. Thermal activation energy is almost constant with electric field. The trap generation rate is large at low field. For thickness, endurance and remanent polarization (Pr) had high correlation in electric-field dependence. Thicker ferroelectric capacitors show lower inflection points in electric-field dependence between low-field and middle-field. For polarization, cycle endurance has a universal relationship with Pr, comprehending electric field and temperature. Taking the analysis above into account, the cycle endurance of FE-HfO2 capacitors can be described by Pr and relevant oxygen vacancies. At low field, cycle endurance is determined by the initial oxygen-vacancy rich region non-uniformly generated in the fabrication process. At middle field, dipole pinning is released, and oxygen vacancies are migrated and redistributed by polarization switching. The breakdown path is formed through the redistributed oxygen vacancies. At high field, the initial oxygen vacancy rich region causes high leakage current and accelerates the breakdown. It is a practical method to evaluate cycle endurance vs Pr for reliability assessment of FE-HfO2 capacitors.