Interlayer-Engineered Local Epitaxial Templating Induced Enhancement in Polarization (2Pr > 70 μC/cm2) in Hf0.5Zr0.5O2 Thin Films

In this work, we report a high remnant polarization,
$2{P}_{r}>$
70
$\mu \text{C}$
/cm
²
in thermally processed atomic layer deposited Hf
_0.5
Zr
_0.5
O
₂
(HZO) film on Silicon with NH
₃
plasma exposed thin TiN interlayer (IL) and tungsten (W) as a top electrode. The effect of IL on the ferroelectric properties of HZO is compared with standard metal–ferroelectric–metal and metal–ferroelectric–semiconductor (MFS) 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. High-resolution transmission electron microscopy (HRTEM) images reveal that the ultrathin TiN acts as a seed layer for the local epitaxy in HZO potentially increasing the strain to produce a
$2\times $
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.