Demonstration of Highly Robust 5 nm Hf_0.5Zr_0.5O₂ 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 metalferroelectric-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 mu C/cm(2) (i.e. 2P(r) = 41 mu C/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 mu C/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.