Ferroelectric Undoped HfO x Capacitor With Symmetric Synaptic for Neural Network Accelerator

A plasma-based ferroelectric undoped HfO x capacitor is fabricated using plasma-enhanced atomic layer deposition (PE-ALD), and the multilevel characteristics of synaptic behavior are investigated. A gradual ferroelectric phase transition in the material is confirmed by grazing incidence X-ray diffraction (GI-XRD) for different O2 plasma periods. The metal–ferroelectric–metal (MFM) capacitor presents excellent remnant polarization ([Formula Omitted]) up to [Formula Omitted]/cm2 and a switching endurance of more than 108 cycles. Superior small potentiation/depression nonlinearity ([Formula Omitted]/−1.66 for voltage modulation stimulation) for synaptic training and almost symmetry training curve ([Formula Omitted]-[Formula Omitted]) are obtained. High stability under multilevel operation with five consecutive cycles of alternating potentiation and depression is exhibited without significant polarization variation for each training step (pulse).