Effect of Domain Structure and Dielectric Interlayer on Switching Speed of Ferroelectric Hf0.5Zr0.5O2 Film

Abstract

The nanosecond speed of information writing and reading is recognized as one of the main advantages of next-generation non-volatile ferroelectric memory based on hafnium oxide thin films. However, the kinetics of polarization switching in this material have a complex nature, and despite the high speed of internal switching, the real speed can deteriorate significantly due to various external reasons. In this work, we reveal that the domain structure and the dielectric layer formed at the electrode interface contribute significantly to the polarization switching speed of 10 nm thick Hf0.5Zr0.5O2 (HZO) film. The mechanism of speed degradation is related to the generation of charged defects in the film which accompany the formation of the interfacial dielectric layer during oxidization of the electrode. Such defects are pinning centers that prevent domain propagation upon polarization switching. To clarify this issue, we fabricate two types of similar W/HZO/TiN capacitor structures, differing only in the thickness of the electrode interlayer, and compare their ferroelectric (including local ferroelectric), dielectric, structural (including microstructural), chemical, and morphological properties, which are comprehensively investigated using several advanced techniques, in particular, hard X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and electron beam induced current technique.

Unravelling the nanoscale mechanism of polarization reversal in a Hf0.5Zr0.5O2-based ferroelectric capacitor by vector piezoresponse force microscopy

“…The results of a comprehensive characterization of the physical and chemical properties of the W/HZO/TiN layered structure used are described elsewhere. 22…”

“…Among them are (1) ferroelectric HfO 2 films doped with Si, 1 Al, Y, etc. ; (2) antiferroelectric HZO films with an increased fraction of zirconium oxide 40 or doped with La and Ga; 30 (3) HZO and HfO 2 films containing a non-ferroelectric monoclinic phase; (4) textured films and films with different grain sizes; and (5) ferroelectric films with different concentrations of charged defects, 22 etc .…”