Improvement in the polarization properties in thin ferroelectric Hf_0.5Zr_0.5O₂ films by two-step flash lamp annealing

Abstract

In this study, we systematically studied the polarization properties of thin ferroelectric Hf0.5Zr0.5O2 (HZO) films annealed by flash lamp annealing (FLA). We have recently proposed a unique annealing method, two-step FLA, which features high temperature annealing with a minimal increase in thermal budget. Using this technique, we observed improvements in the polarization properties in 5nm HZO films. These were an increase in the remanent polarization (2Pr) to 24.2 µC/cm2 and better durability compared with other more conventional annealing techniques. In addition, we confirmed that there was no degradation in 2Pr under thermal stress. Two-step FLA is one of the effective ways to obtain ferroelectricity with high values of 2Pr and good durability in HZO films thinner than 5nm.