Back-End of Line Compatible Hf0.5Zr0.5O2 With ZrO2 Seed Layer for Enhanced Ferroelectricity

In this letter, four ferroelectric (FE) capacitors with thickness dependent ZrO
₂
seed layer (SL) were designed and fabricated at a low annealing temperature below 350 °C. By modulating the thickness of ZrO
₂
SL, it is demonstrated that the FE capacitor with 1 nm ZrO
₂
SL exhibits a superior remnant polarization (
$2{P} _{r}$
) of
$44.1 ~\mu \text{C}$
/cm
²
under 3 MV/cm at 1 kHz and
$2{P} _{r}$
of
$17.6 ~\mu \text{C}$
/cm
²
after
$10^{{9}}$
cycles at 3 MV/cm. It is found that the 1 nm ZrO
₂
SL provides more growth sites for the Hf
_0.5
Zr
_0.5
O
₂
(HZO) thin films, and enhances the ratio of the ferroelectric phases during crystallization, thereby leading to enhancement of its ferroelectricity and reliability. This work provides a robust solution to improve both ferroelectricity and endurance for future ferroelectric device compatible with back end of line (BEOL) process.