Recovery Strategy of Fatigue-Limited Endurance in Si FeFETs With Thin HfZrO₂ Films

This study demonstrates that memory window (MW) narrowing under low voltage is caused by fatigue (polarization decrease) and can be recovered, whereas that under high voltage is caused by interface degradation and is not easily recoverable. Furthermore, we have found that the electrical field across Hf0.5Zr0.5O2 (HZO) layer (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\text {HZO}}$ </tex-math></inline-formula>) is the key to determine the recoverable ferroelectric fatigue, while the voltage applied on the gate (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {g}}$ </tex-math></inline-formula>) is associated with the interface degradation. Thus, thin HZO ferroelectric FETs (FeFETs) can prevent severe interface degradation through low-voltage operation (low <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {g}}$ </tex-math></inline-formula>). Moreover, by systematically studying the endurance behavior and recovery strategies, we show that a recovery scheme with bipolar pulses with suitable voltage and short total time of a few microseconds is effective to recover MW narrowing of FeFETs due to ferroelectric fatigue. As a result, HZO thickness scaling is effective to achieve high endurance characteristics of FeFETs via recovery.