Interlayer-Engineered Local Epitaxial Templating Induced Enhancement in Polarization (2P(r) > 70 mu C/cm(2)) in Hf0.5Zr0.5O2 Thin Films

In this work, we report a high remnant polarization, 2P(r) > 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 (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 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.