Improved Endurance of Hf₀.₅Zr₀.₅O2-Based Ferroelectric Capacitor Through Optimizing the Ti–N Ratio in TiN Electrode

In this letter, the endurance performance of the TiN/Hf
_0.5
Zr
_0.5
O
₂
(HZO)/TiN ferroelectric capacitor is significantly improved by increasing the N content of the TiN top electrode. The gas with different N
₂
flow is used in the top TiN electrode sputter process. Compared to N-deficient capacitor, the leakage current density of the N-rich capacitor is reduced by sixfold (from
$1.7\,\,\times10$
⁻⁵

$\text{A}/$
cm
²
to
$9.2\,\,\times10$
⁻⁶

$\text{A}/$
cm
²
), the dielectric constant is increased correspondingly. The endurance is improved by three orders of magnitude (from 10
⁶
to over
$3\,\,\times10$
⁹
at 3 V read voltage) because of the addition of more N
₂
flow. And it enhances breakdown voltage and the TDDB reliability. The reduction in defects (especially oxygen-vacancies) near the interface in the N-rich capacitor is responsible for the improvement.