Interrelation between ferroelectric properties and defects based on low-frequency noise analysis of HZO ferroelectric capacitor

Abstract

Switching characteristics of ferroelectrics depend on the fabrication conditions and phase-transition results of each fabrication recipe. Here, the pulsed I–V and positive-up negative-down plots of hafnium zirconium oxide ferroelectric capacitors (FeCaps) are analyzed using low-frequency noise (LFN), an electrical method to investigate defects including oxygen vacancies that are key elements influencing polarization properties. This is a new trial at adopting the LFN method for analysis of FeCaps to find interrelation ferroelectric characteristics and defects depending on the annealing conditions. Increasing power spectral density (PSD) levels are observed with increasing annealing temperature and time. Moreover, the nature of the defects reflected in the PSD is examined via x-ray photoelectron spectroscopy. Correlations are observed between the defects, including oxygen vacancies and ZrOx defects, and FeCap properties. High intrinsic polarization is observed when the density of defects is large; this shows that oxygen vacancies and ZrOx defects in FeCaps may enhance the orthorhombic phase by inducing lattice strain. These findings are expected to facilitate LFN studies of ferroelectrics and the fundamental understanding of their electrical properties from defects and oxygen vacancy analyses.