Atomic Layer Deposition Plasma-Based Undoped-HfO 2 Ferroelectric 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.