Study on the effect of heat treatment conditions on metalorganic-chemical-vapor-deposited ferroelectric Hf_0.5Zr_0.5O₂thin film on Ir electrode

The effect of the heat treatment conditions on the constituent phases and electrical properties of (Hf_0.5Zr_0.5)O₂films deposited by the metalorganic chemical vapor deposition was investigated. By using a low temperature or short duration for post-heat treatment after the deposition, the volume fraction of the tetragonal phase increases, resulting in a high dielectric constant. On the other hand, the volume fraction of the monoclinic phase increased in the films that were heat-treated at higher temperatures and exposed to longer heat treatment duration. The ferroelectric with and dielectric properties of these films were greatly inferior. Superior ferroelectric properties a significant volume fraction of orthorhombic phase were achieved for intermediate heat treatment conditions. These results give useful information to understand the origin of the ferroelectricity and to control the phases and electrical properties in HfO₂-based films.