Interlayer-Engineered Local Epitaxial Templating Induced Enhancement in Polarization (2<i>P<sub>r</sub> </i> > 70 <i>μ</i>C/cm<sup>2</sup>) in Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub> Thin Films
Srinu Rowtu, Paritosh Meihar, Adityanarayan H. Pandey, Md. Hanif Ali, Sandip Lashkare, Udayan Ganguly
Abstract
In this work, we report a high remnant polarization, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2{P}_{r}>$ </tex-math></inline-formula> 70 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{C}$ </tex-math></inline-formula> /cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> in thermally processed atomic layer deposited Hf <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> Zr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (HZO) film on Silicon with NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times $ </tex-math></inline-formula> improvement in the remnant polarization. Finally, the HZO devices are shown to be wake-up-free and exhibit endurance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${10}^{{6}}$ </tex-math></inline-formula> cycles. This study opens a pathway to achieve epitaxial ferroelectric HZO films on Si with improved memory performance.