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.