Area Scalable Hafnium-Zirconium-Oxide Ferroelectric Capacitor Using Low-Temperature Back-End-of-Line Compatible 40°C Annealing

Improving the area scalability and reducing the process temperature of Hf
0.5
Zr
0.5
O
2
(HZO) ferroelectric (FE) capacitors are two of the most critical challenges in future back-end-of-line (BEOL) compatible FE memories. This paper presents the first study demonstrating the existence of a tradeoff between the area scalability and the annealing temperature, suggesting that these two should be optimized simultaneously rather than separately. Optimizing the HZO thickness and Hf:Zr ratio are identified to improve the tradeoff. High remanent polarization density of 24 μC/cm
²
and excellent endurance of 9×10
⁹
cycles are achieved in a scaled FE area as small as 0.6×0.6 μm
²
by using the BEOL-compatible 400°C annealing.