Sub 5 Å-EOT HfₓZr1–xO₂ for Next-Generation DRAM Capacitors Using Morphotropic Phase Boundary and High-Pressure (200 atm) Annealing With Rapid Cooling Process

Achieving low equivalent oxide thickness (EOT) with CMOS-compatible materials is of prime importance for further miniaturization of dynamic random access memory (DRAM) technology. Despite several efforts made in this regard, especially by using high dielectric constant (
$\kappa $
) materials, utilization of novel electrodes to counterfeit the high leakage current limits its immediate implementation. Herein, we experimentally demonstrate CMOS-compatible ~4.8 Å-EOT ferroelectric (FE) Zr-rich Hf
_x
Zr
_1–x
O
₂
(HZO) with morphotropic phase boundary (MPB) formed by high-pressure annealing (HPA) and rapid cooling (RC) processes for next-generation DRAM device applications. Such low EOT was achieved by precise process optimization such as HZO composition, annealing condition, and thickness in the vicinity of MPB. The utilization of HPA reduces the physical thickness for emergence of MPB in Zr-rich HZO films, whereas the RC of the HPA samples reduces the leakage current considerably. A maximum dielectric constant (
$\kappa $
) of ~49 was achieved for 6.0-nm HZO [1:2] films for 500 °C HPA-RC resulting in an EOT as low as ~4.8 Å. This is the lowest among all reported EOT value using CMOS-compatible HZO films with leakage current <10
⁻⁷
A/cm
²
using TiN as top and bottom electrodes and can be of significant importance for the future DRAM technology.