Demonstration of Highly Robust 5 nm Hf0.5Zr0.5O₂ Ultra-Thin Ferroelectric Capacitor by Improving Interface Quality

In this letter, 5 nm-thick HZO ultra-thin ferroelectric capacitors with excellent remanent polarization (P
_r
) and reliability are presented. The TiN/HZO/TiN metal-ferroelectric-metal (MFM) capacitor stack was deposited consecutively in the same atomic layer deposition (ALD) system without breaking the vacuum (i.e. “in-situ” like) to improve the interface quality between TiN electrodes and HZO ferroelectric layer. The samples show high P
_r
of 20.5 μC/cm
²
(i.e. 2P
_r
= 41 μC/cm
²
) under driving voltage of 3 V with low coercive voltage of approximately 0.6 V. The robustness of the MFM capacitor was presented by the outstanding endurance characteristics for keeping 2P
_r
value higher than 20 μC/cm
²
after 10
¹⁰
cycles at a high electric field of 5 MV/cm without breakdown, though the P
_r
values gradually degrade with cycles at low field (i.e. 2.4 MV/cm). The highly robust endurance characteristics of the 5nm-thick HZO MFM capacitor indicate the good interface quality achieved in this study.