Atomic Layer Deposition Plasma-Based Undoped-HfO2 Ferroelectric FETs for Non-Volatile Memory

A plasma-based undoped-HfO
₂
FeFET (ferroelectric FET) with non-volatile memory characteristics is demonstrated. Modifying the O
₂
plasma period in plasma-enhanced atomic layer deposition (PE-ALD) is an effective approach to enhance the remnant polarization ( P
_r
) up to 2P
_r
= 25 μC/cm
²
for the MFM (metal/ferroelectric/metal) structure with ferroelectric undoped-HfO
₂
thin films, and successful integration is implemented for the FeFET. The appropriate O
₂
vacancies ( V
_o
²⁺
) benefit the formation of the ferroelectric phase since they play the role of dopants and help orthorhombic phase (o-phase) formation during post-metal annealing (PMA). The V
_o
²⁺
-rich undoped-HfO
₂
FeFET exhibits a memory window (MW) of 0.5 V, 5 ×10
⁴
switching endurance cycles, and higher than $10^{{4}}$ sec of data retention with V
_P/E
= ±5 V.