Investigation of annealing temperature dependent sub-cycling behavior for HfZrOx-based ferroelectric capacitor

Abstract

Ferroelectric HfO2 thin film has been widely explored due to its superior characteristics, such as high switching speed, scalability, and long data retention. However, it still faces challenges in achieving good stability due to the wake-up and split-up effects. In this study, the sub-cycling behavior of Hf0.5Zr0.5O2-based ferroelectric capacitors (FeCaps) with various annealing temperatures is investigated. Our results suggest that the FeCaps with higher annealing temperatures demonstrate an increased resistance to the split-up effect and exhibit less distorted hysteresis loops compared to their lower-temperature counterparts. Symmetrical sub-cycling reveals pronounced current split-up and diminished switching current peaks in the FeCaps with lower annealing temperatures, whereas those annealed at higher temperatures show minimal current split-up and enhanced performance. Asymmetrical sub-cycling shows that lower annealing temperatures cause local domain pinning, while higher temperatures result in imprint-like behavior. Synchrotron-based extended x-ray absorption fine structure and hard x-ray photoelectron spectroscopy analyses reveal the potential of nitrogen doping in HfZrOx under high-temperature annealing processes, forming the Hf–N species to mitigate the amount of charged oxygen vacancy (VO2+) in the interfacial region. This study elucidates the relationship between VO2+ distribution and the split-up effect during sub-cycling, providing critical insights for enhancing the sub-cycling performance and stability of HfO2-based devices.