Top Electrode Engineering for High‐Performance Ferroelectric Hf0.5Zr0.5O2 Capacitors

Abstract This work systematically studies the TiN, Ru, and RuO 2 top electrodes (TEs) effects on the ferroelectric properties of Hf 0.5 Zr 0.5 O 2 (HZO) films. The Ru top electrode significantly improves the ferroelectric performance even with the conventional TiN bottom electrode. The high two‐remanent polarization (2 P r ) value (≈65 µC cm −2 ) is obtained with the capacitor with Ru TE, which is ≈1.5 times higher than that of the capacitors with the TiN and RuO 2 TEs. Moreover, it does not break down to 1 × 10 9 cycling with a high cycling electric field of 4.0 MV cm −1 , while others do lower cycle numbers. Further enhancement can be achieved by inserting a 2‐nm‐thick HfON interfacial layer between the HZO film and TiN bottom electrode while keeping the Ru/HZO top interface structure. The capacitor does not break down even at an electric field strength of 4.8 MV cm −1 , at which a 2 P r value of ≈67 µC cm −2 is achieved. Furthermore, it can endure 1 × 10 11 switching cycles while a 2 P r value of 45–53 µC cm −2 is retained. Therefore, this study elucidates that interfacial engineering is an important technology that can overcome the trade‐off relationship between P r and endurance, a critical issue in ferroelectric doped HfO 2 ‐based films.