Improvement of endurance and switching speed in Hf_1−x Zr _x O₂ thin films using a nanolaminate structure

Abstract

To improve the endurance and polarization switching speed of Hf1-xZrxO2 (HZO) ferroelectric films, we designed a 10-nm Hf0.5Zr0.5O2 + ZrO2 (HZZ) nanolaminate structure. Three films with different ZrO2 interlayers thicknesses were compared to find the optimal condition to implement the effect of the topological domain wall which was proposed recently. The HZZ film were deposited by repeatedly stacking ten HZO (~0.92 nm) and six ZrO2 (~0.53 nm) layers; they exhibited a dramatic reduction of coercive field without an effective loss of remnant polarization. The endurance at operation voltage increased by more than 100 times compared with that of the solid solution HZO film, and the switching speed was increased by more than two times. The formation of the tetragonal phase-like spacer between the ferroelectric polar regions appears to be the main factor associated with the reduction of the switching barrier and leads to the acceleration of the switching propagation over multiple domains.

Back‐End‐of‐Line Integration of Synaptic Weights using HfO2/ZrO2 Nanolaminates

“…From Figure 7b, we observe that the pristine cycle (black curve) shows two local maxima for the positive bias, which could indicate the presence of an as‐grown anti‐ferroelectric phase, as observed in HfZrO 4 –ZrO 2 nanolaminates. [ 54 ] From 5e5 to 1e11 cycles, we observe the presence of one local maximum for each polarity, characteristic of ferroelectric materials. The voltage at which the negative maximum is observed shifts from −0.85 to −0.36 V upon cycling, whereas no shift is observed for the positive branch.…”