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

Abstract

AbstractThis work systematically studies the TiN, Ru, and RuO2 top electrodes (TEs) effects on the ferroelectric properties of Hf0.5Zr0.5O2 (HZO) films. The Ru top electrode significantly improves the ferroelectric performance even with the conventional TiN bottom electrode. The high two‐remanent polarization (2Pr) 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 RuO2 TEs. Moreover, it does not break down to 1 × 109 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 2Pr value of ≈67 µC cm−2 is achieved. Furthermore, it can endure 1 × 1011 switching cycles while a 2Pr 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 Pr and endurance, a critical issue in ferroelectric doped HfO2‐based films.