Ferroelectric recovery of scaled-down Y-doped HfO thin films on NiSi after annealing.

In this work, the ferroelectric properties of Y-doped HfO (YHO) thin films with a physical thickness ranging from 42 nm to 7.4 nm deposited on NiSi are reported. Ferroelectricity in scaled-down YHO is heavily impacted by the following factors: (1) depolarizing fields developed at non-ferroelectric interfacial layers whose thickness is dependent on annealing conditions and (2) the increasingly larger leakage current that develops in thinner YHO films. The lowest remanent polarization () is obtained in thinner YHO films since the non-ferroelectric interfacial layer and the total leakage current introduce larger contributions towards the lack of control on dipoles' switching dynamics and, therefore, the final . Nevertheless, by adjusting annealing conditions, even thinner YHO films can gradually recover their ferroelectric properties; thus, a simple trade-off between the YHO annealing temperature and leakage current could help in the recovery of in YHO-based thinner films.