Abstract
The formation of an interfacial layer is believed to affect the ferroelectric properties in HfO2 based 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 (ALD) 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 (XPS) analyses done on devices W/HZO/W and W/HZO/IrOx suggest the strong effect of IrOx in controlling bottom interfacial layer formation while W/HZO/W badly suffers from interfacial layer formation. W/HZO/IrOx devices show high remnant polarization (2Pr) ~ 53 µC/cm2, wake-up free endurance cycling characteristics, low leakage current with demonstration of low annealing temperature requirement as low as 350°C, valuable for BEOL integration. Further, sub-5 nm HZO thicknesses-based W/HZO/IrOx devices demonstrate high 2Pr and 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/IrOx devices show 2Pr values 13.54, 22.4, 38.23 µC/cm2 at 4 MV/cm and 19.96, 30.17, 48.34 µC/cm2 at 5 MV/cm, respectively, with demonstration of wake-up free ferroelectric characteristics.
