Interlayer-engineered local epitaxial templating induced enhancement in polarization (2P${}_r$ > 70$\mu$C/cm${}^2$) in Hf${}_{0.5}$Zr${}_{0.5}$O${}_2$ thin films

Abstract

In this work, we report a high remnant polarization, 2Pr >70$\mu$C/cm${}^2$ in thermally processed atomic layer deposited Hf0.5Zr0.5O2 (HZO) film on Silicon with NH3 plasma exposed thin TiN interlayer and Tungsten (W) as a top electrode. The effect of interlayer on the ferroelectric properties of HZO is compared with standard Metal-Ferroelectric-Metal and Metal-Ferroelectric-Semiconductor structures. X-Ray Diffraction shows that the Orthorhombic (o) phase increases as TiN is thinned. However, the strain in the o-phase is highest at 2 nm TiN and then relaxes significantly for the no-TiN case. HRTEM images reveal that the ultra-thin TiN acts as a seed layer for the local epitaxy in HZO potentially increasing the strain to produce a 2X improvement in the remnant polarization. Finally, the HZO devices are shown to be wake-up-free, and exhibit endurance >10^6 cycles. This study opens a pathway to achieve epitaxial ferroelectric HZO films on Si with improved memory performance.

6 pages, 6 figures

References in corpus (2)

• The Origin of Ferroelectricity in Hf${}_x$ Zr${}_{1-x}$ O${}_2$: A Computational Investigation and a Surface Energy Model
• Impact of Four-Valent Doping on the Crystallographic Phase Formation for Ferroelectric HfO${}_2$ from First-Principles: Implications for Ferroelectric Memory and Energy-Related Applications