Electrical Investigation of Wake-Up in High Endurance Fatigue-Free La and Y Doped HZO Meal-Ferroelectric-Metal Capacitors

Abstract

High endurance of 10(11) cycles is demonstrated in similar to 9-10-nm stoichiometric Hafnium Zirconate(HZO) metal-ferroelectric-metal (MFM) capacitors deposited using CI precursors with La and Y dopants. La doping is shown to offer higher remnant polarization than Y. Investigation of doped layers with asymmetric polarization versus electric field (P-E) measurements and unipolar fatigue cycles suggests that in the pristine state, the HZO is comprised of ferroelectric domains with internal built-in electric field-induced pinned coercive field (E-c). Doping is shown to increase the pinning effect and two distinct groups of ferroelectric domains emerge, which is antialigned at zero applied electric field (E). The antiferroelectric-like (pinched P-E loop) behavior is therefore attributed to internal built-in E-induced pinning of the domains during growth and/or annealing steps. The initial wake-up is attributed to gradual depinning of the domains with bipolar electric pulses. Suppression of monoclinic phase was observed in doped layers that survive 10(11) cycles. The wake-up is shown to be dependent on total duration and magnitude of bipolar electric pulses. Precycling scheme is demonstrated for stable operation at a lower field.