Ferroelectricity of HfxZr1−xO2 thin films fabricated by 300 °C low temperature process with plasma-enhanced atomic layer deposition

Abstract

We investigated the characteristics of 10-nm-thick ferroelectric Hf0.43Zr0.57O2 (HZO) thin films fabricated using plasma-enhanced atomic layer deposition (PE-ALD) at 300 °C with plasma O2 gas and a post metallization annealing (PMA) process at 300–400 °C. The as-grown HZO film had a nanocrystalline structure (5–10 nm) with ferroelectric orthorhombic, tetragonal, and cubic (O/T/C) phases, and the PMA process subsequently led to the crystal growth of O/T/C phases along the nanocrystals in the as-grown film. As a result, the 300 °C-PMA-treated HZO film exhibited excellent remanent polarization (2Pr = Pr+ − Pr−) and dielectric constant (k) of 34 μC/cm2 and 39, respectively. These results suggest that the formation of the nanocrystal grains in as-grown HZO film could play an important role in the fabrication of HZO films with the metastable O/T/C phases during a low temperature fabrication process at 300 °C to obtain a superior ferroelectricity.