Structural Characteristics of Electrically Scaled ALD HfO2 from Cyclical Deposition and Annealing Scheme

Abstract

We have recently reported electrical performance improvements in atomic layer deposited (ALD) HfO2 films grown by use of a cyclical deposition and annealing scheme (termed DADA) compared to a single deposition followed by a post-deposition anneal (PDA). We previously proposed a model for bottom-up crystallization in DADA films in contrast to random crystallization for PDA films. To elucidate the mechanisms for this structural modification, in this study we utilized grazing incidence in-plane X-ray diffraction and pole figure measurements using synchrotron radiation as well as transmission electron microscopy. Structural differences were investigated from different annealing conditions as well as from different thickness of films. We observed significant differences in structural properties of DADA films compared to films receiving PDA. We also report on the evolution of monoclinic HfO2 with a (-111) preferred orientation (fiber texture) for DADA films whereas PDA treatment resulted in a random grain alignment and mixed phase structure.