Oxygen diffusion coefficients in the metastable ferroelectric phase of polycrystalline hafnium zirconium oxide (HZO) thin films have been quantified using 18O tracers and time-of-flight secondary ion mass spectrometry. 11.5 nm thick HZO films containing 16O were deposited by plasma-enhanced atomic layer deposition followed by post-metallization annealing to crystallize into the ferroelectric phase. A 1.2 nm thick HZO layer containing 18O was then deposited using thermal atomic layer deposition with H218O as a reactant. Thermal anneals were conducted at 300, 350, and 400 °C and the ferroelectric phase confirmed after the anneals by x-ray diffraction, infrared spectroscopy, and electrical property measurements. 18O depth profiles were measured and fit with a thin film diffusion equation to determine the oxygen diffusion coefficients. Oxygen diffusion coefficients ranged from approximately 2 × 10−18 cm2/s at 300 °C to 5 × 10−17 cm2/s at 400 °C with an activation energy of 1.02 ± 0.24 eV.

Hafnium zirconium oxide (HZO) has attracted attention for applications in nonvolatile memory and energy harvesting devices. However, it faces practical challenges such as insufficient endurance. One promising strategy to address this limitation is the utilization of antiferroelectric (AFE) behavior in HZO‐based materials. Previous studies have shown that various metal substitutions into HZO can result in AFE‐like properties within specific substitution concentration windows. While AFE‐like properties have often been attributed to the tetragonal phase of ZrO ₂ , recent studies suggest that the antipolar orthorhombic phase (space group Pbca ) may instead be responsible for the observed AFE behavior. This study investigates how varying aluminum substitution concentration influences the phase and electrical properties of HZO devices to clarify the origin of AFE behavior. The results demonstrate that low aluminum concentrations in HZO, particularly in 8:1 and 6:1 HZO:Al composition ratio HZO devices, lead to pronounced real AFE behavior associated with the formation of the Pbca phase.

The effects of biaxial stress in hafnium zirconium oxide (HZO) thin films on the phase constitution and dielectric response are studied through the preparation of HZO films on substrates with coefficients of thermal expansion (CTE) ranging from 0.52 to 12.97 × 10−6 K−1. X-ray diffraction-based stress measurements revealed a systematic decrease in film biaxial tensile stress with increasing substrate CTE. Grazing incidence and attenuated total reflectance Fourier transform infrared spectroscopy revealed spectral energy shifts that scale with film stress, proving vibrational spectroscopy as an additional indicator of film stress. Ferroelectric responses are observed in HZO prepared on low CTE substrates, and antiferroelectric-like responses are observed in films on high CTE substrates. Results indicate that reducing substrate CTE increases tensile biaxial stress and results in higher fractions of the metastable polar orthorhombic phase. High substrate CTE values lead to low HZO stress values and spectroscopic and antiferroelectric responses consistent with the presence of the antipolar o-I phase.

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.