Strategy Toward HZO BEOL-FeRAM with Low-Voltage Operation (≤ 1.2 V), Low Process Temperature, and High Endurance by Thickness Scaling

The potential of thickness scaling in ferroelectric Hf
0.5
Zr
0.5
O
2
(HZO) is investigated by a systematic study on MFM capacitors with HZO thickness from 9.5 nm down to 2.8 nm. We establish the thickness-temperature mapping indicating a clear tradeoff between the thickness scaling and crystallization temperature, which has to be taken into account in the implementation as back-end-of-line (BEOL) FeRAM. Utilizing the thickness scaling and high-field wake-up without reliability loss, we demonstrate 4-nm-thick HZO having low crystallization temperature (500°C), excellent ferroelectricity (2P
r
> 25 μC/cm
²
), low operating voltage (0.7-1.2 V), and high read/write endurance (projected to 10
¹⁴
).