Atomic Layer Deposition Plasma-Based Undoped-HfO₂Ferroelectric FETs for Non-Volatile Memory

A plasma-based undoped-HfO2 FeFET (ferroelectric FET) with non-volatile memory characteristics is demonstrated. Modifying the O2 plasma period in plasma-enhanced atomic layer deposition (PE-ALD) is an effective approach to enhance the remnant polarization ( \text{P} {\text {r}} ) up to 2P {\text {r}} = 25\,\,\mu \text{C} /cm2 for the MFM (metal/ferroelectric/metal) structure with ferroelectric undoped-HfO2 thin films, and successful integration is implemented for the FeFET. The appropriate O2 vacancies ( \text{V} {\text {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 \text{V} {\text {o}} {{2}+} -rich undoped-HfO2 FeFET exhibits a memory window (MW) of 0.5 V, {5} \times {10} {{4}} switching endurance cycles, and higher than 10 {{4}} sec of data retention with \text{V} {\text {P/E}} = \pm 5 V.