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.