High polarization and wake-up free ferroelectric characteristics in ultrathin Hf0.5Zr0.5O2devices by control of oxygen-deficient layer.

The formation of an interfacial layer is believed to affect the ferroelectric properties in HfO2based ferroelectric devices. The atomic layer deposited devices continue suffering from a poor bottom interfacial condition, since the formation of bottom interface is severely affected by atomic layer deposition and annealing process. Herein, the formation of bottom interfacial layer was controlled through deposition of different bottom electrodes (BE) in device structure W/HZO/BE. The transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy analyses done on devices W/HZO/W and W/HZO/IrOxsuggest the strong effect of IrOxin controlling bottom interfacial layer formation while W/HZO/W badly suffers from interfacial layer formation. W/HZO/IrOxdevices show high remnant polarization (2Pr) ∼ 53μC cm-2, wake-up free endurance cycling characteristics, low leakage current with demonstration of low annealing temperature requirement as low as 350 °C, valuable for back-end-of-line integration. Further, sub-5 nm HZO thicknesses-based W/HZO/IrOxdevices demonstrate high 2Prand wake-up free ferroelectric characteristics, which can be promising for low power and high-density memory applications. 2.2 nm, 3 nm, and 4 nm HZO based W/HZO/IrOxdevices show 2Prvalues 13.54, 22.4, 38.23μC cm-2at 4 MV cm-1and 19.96, 30.17, 48.34μC cm-2at 5 MV cm-1, respectively, with demonstration of wake-up free ferroelectric characteristics.