PDA-Processed Hafnium-Based Capacitors With Ultrahigh-k (~81) Enabled by Capping Layers for Capacitive Memory Applications

Abstract

HfO₂/ZrO₂-based capacitors typically require post-metallization annealing (PMA) to achieve ultrahigh- $k$ dielectric properties. Here we report a post-deposition annealing (PDA) process on H ${\mathrm{f}}_{{0}.{3}}$ ${\mathrm{Zr}}_{{0}.{7}}$ O₂ capacitors with a mixed TiO₂/Al₂O₃ capping layer. The uncapped HZO device exhibits a ferroelectric-like loop ( $k \sim 42$ at 0 V), whereas the capped device exhibits intermediate $k$ –V profile between FE-like and AFE-like responses, characterized by a pronounced near-zero-field high-k response with an ultrahigh-k value of ~81 at 0 V. The interfacial asymmetry also contributes non-destructive capacitive readout. The capacitive memory window (CMW $\varepsilon _{\text {r}}\text {)}$ of ~15 is maintained after $10^{{10}}$ write cycles at 2.4 V. A charge-based CMW_Q of $1.08\mu $ C/cm² persists after $10^{{9}}$ read cycles at 0.5 V. This work demonstrates a PDA-processed HZO capacitor that simultaneously delivers ultrahigh-k and non-destructive readout, achieving a maximum k value of ~81 at $550~^{\circ }$ C and retaining a $\kappa $ value of ~77 under a $400~^{\circ }$ C thermal budget.