Characterization of Fatigue and Its Recovery Behavior in Ferroelectric HfZrO

The discovery of ferroelectric properties in HfO
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-based materials has attracted immense interest in both logic and memory applications. However, the degradation in remnant polarization upon repeated cycles is a major concern for reliability, but the mechanism remains unclear. In this study, polarization fatigue of HfZrO ferroelectric is investigated with SILC (stress-induced-leakage-current) measurement under different E-field stresses. Under high-field, we observed strong correlation between polarization wake-up and SILC increase. This is attributed to oxygen vacancy redistribution and percolation path formation, especially at high frequency cycling. However, polarization fatigue at low field is found to occur without SILC increase. P-E loop measurements and material analysis by TEM/PED (precession electron diffraction) revealed that charge trapping is the main contributor under the low-bias. We demonstrated that the fatigue caused by low-field stress could be effectively recovered through an interspersed periodical, short-term cycles at high-field to manage charge trapping and oxygen vacancy redistribution, thus resulting in prolonged endurance to >1E12 cycles without SILC degradation at room temperature. We also validated that a negligible fatigue switching in HfZrO can be achieved at -40°C as low-temperature operation further reduces charge trapping.