Improvement of Ferroelectricity and Reliability in Hf0.5Zr0.5O2 Thin Films With Two-Step Oxygen Vacancy Engineering

A two-step oxygen vacancy (V
_O
) engineering technique is presented to enhance the ferroelectricity of Hf
_0.5
Zr
_0.5
O
₂
(HZO) film with superior dielectric reliability. The V
_O
engineering consists of two steps: 1) V
_O
formation in the HZO film to stabilize the orthorhombic phase and 2) V
_O
passivation to annihilate the V
_O
-related defects without degrading the ferroelectric properties. In addition, we further investigate the feasibility of the two-step V
_O
engineering at a low thermal budget process (400 °C) for back-end-of-line (BEOL) applications. Superior remnant polarization (2P
$_{\text {r}} = 43\,\,\mu \text{C}$
/cm
²
) and high endurance of
$> 10^{{8}}$
cycles are demonstrated in HZO thin films processed at 400 °C, which are comparable to those processed at high temperatures.