Enhanced Ferroelectric Phase Formation via Local Structure Modification in the Pre-Crystalline State of Hafnium Zirconium Oxide Thin Films

Ferroelectric hafnium zirconium oxide is one of the most promising materials for non-volatile memory applications due to its stability at small size scales and compatibility with robust fabrication techniques. However, the manufacture of phase-pure ferroelectric hafnia remains an elusive challenge due to its sensitivity to synthesis and integration factors. This work reports on the use of argon plasma atomic layer annealing during atomic layer deposition growth as a route to enhance formation of the ferroelectric phase in hafnium zirconium oxide thin films. The introduction and the lengthening of the duration of atomic layer annealing enhance the ferroelectric properties of the films that form after a rapid thermal anneal. This is observed through Fourier transform infrared spectroscopy and corroborated via scanning transmission electron microscopy, polarization measurements, and piezoresponse force microscopy. Qualitative analysis of the extended X-ray absorption fine structure region reveals a change in the second-nearest-neighbor environment of the absorbing species in the amorphous deposit as atomic layer annealing duration varies. This change in the local structure creates a more favorable environment for ferroelectric phase crystallization, positioning atomic layer annealing as a processing route to facilitate hafnia-based films with increased ferroelectric phase concentrations and virtually no polarization wake-up.