Demonstration of Wake-Up Free 6 nm Ultrathin ZrO₂-HfO₂ Superlattice Ferroelectric Capacitors With High Endurance Against Fatigue

This study presents the ferroelectric polarization stability characteristics of ultrathin (6 nm) superlattice (SL) ferroelectric layer metal-ferroelectric-metal (MFM) capacitors fabricated with varying ferroelectric layer stacks. Notably, ZrO2-HfO2 SL MFM capacitors with 1 nm ZrO2 as the starting layer exhibited enhanced polarization stability characterized by nearly wake-up free and fatigue-free behavior. The research demonstrates the deposition of ZrO2-HfO2 superlattice by atomic layer deposition (ALD), resulting in highly stable remanent polarization (2Pr @ 3.3 MV/cm) of approximately
$30~\mu $
C/cm2. The variation remained small (
$\Delta 2$
P
$_{\text {r}} \le 2.5~\mu $
C/cm2;
$\Delta 2$
Pr/2P
$_{\text {r, {pristine}}} \le 8$
%) over an impressive
$10^{{10}}$
cycles of field cycling. This result is a crucial technique to address the polarization instability commonly reported in ultrathin (
$\le 6$
nm) Hf
$_{{0}.{5}}$
Zr
$_{{0}.{5}}$
O by utilizing the SL structure to achieve nearly wake-up free and fatigue-free polarization performance up to
$10^{{10}}$
cycles.