Ferroelectric Zr0.5Hf0.5O2 thin films for nonvolatile memory applications

TLDR

We report the observation of ferroelectricity in capacitors based on hafnium‑zirconium‑oxide. Ferroelectricity was confirmed through quasi‑static polarization‑voltage hysteresis, small‑signal capacitance‑voltage, and piezoelectric measurements, and retention was assessed using a Positive Up Negative Down pulse technique. Hf₀.₅Zr₀.₅O₂ thin films of 7.5 to 9.5 nm thickness exhibited ferroelectric polarization‑voltage hysteresis loops in TiN‑based MIM capacitors, with a remnant polarization of 16 μC/cm² and a coercive field of 1 MV/cm, and no significant decay of the initial polarization state was observed within two days.

Abstract

We report the observation of ferroelectricity in capacitors based on hafnium-zirconium-oxide. Hf0.5Zr0.5O2 thin films of 7.5 to 9.5 nm thickness were found to exhibit ferroelectric polarization-voltage hysteresis loops when integrated into TiN-based metal-insulator-metal capacitors. A remnant polarization of 16 μC/cm2 and a high coercive field of 1 MV/cm were observed. Further proof for the ferroelectric nature was collected by quasi-static polarization-voltage hysteresis, small signal capacitance-voltage, and piezoelectric measurements. Data retention characteristics were evaluated by a Positive Up Negative Down pulse technique. No significant decay of the initial polarization state was observed within a measurement range of up to two days.